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Taihu Lake, the third largest freshwater lake in China, has experienced rapid salinization in the past decades; however, little is known about the impact of sodium (Na) on ion exchange in the lake environment. To explore the potential effect of increased Na on the migration of base cations (Ca and Mg) and resulting redistribution between the water and sediment, we used the adsorption-exchange experiment, MINTEQ modeling to explore the cation exchange induced by high Na input, and its impact on the redistribution of Ca and Mg in Taihu different media. The results indicated that exchanged quantity of Ca and Mg increased with time, and the exchange process reached 90% during 0–4 h and reached equilibrium after 24 h under 100 mg/L Na (the maximum Na concentration in Taihu sediment pore water). Our MINTEQ modeled result indicated that the exchanged quantity of Ca and Mg increased with the increasing Na concentration, with Ca being preferably exchanged over Mg at the same Na concentration. The MINTEQ model further predicted that, in the Taihu lake environment, the exchange adsorption would reach the equilibrium at the concentration of 6000 mg/L Na, with exchanged Ca2+ and Mg2+ accounting for 47% and 55% of the total exchangeable Ca and Mg in the sediment, respectively. Although current Na-induced exchange in the Taihu lake has been far from the equilibrium, the MINTEQ result confirmed the existence of this reaction and predicted the potential redistribution of base cations or Ca/Mg ratio in the lake sediment and water phase with further Na increase. Furthermore, our field observations not only confirmed the existence of Na-induced cation exchange in this lake environment but also were generally in agreement with our experimental and modeled results. The increased salinization-induced ion exchange would alter the re-distribution of base cations and the resulting potential ecosystem consequences should be given close attention in this large freshwater lake. [ABSTRACT FROM AUTHOR]

The groundwater environment in low-lying coastal regions is significantly impacted by global sea-level fluctuation. In Laizhou Bay, three large-scale transgressions have occurred since the late Pleistocene, resulting in the transformation of ancient seawater into brine. This brine has become a major contributor to groundwater salinity in the area. This study establishes a correlation between groundwater occurrence and paleoclimate changes in Laizhou Bay using borehole sediment data. The source and mechanism of groundwater salinity are analyzed based on sediment pore water characteristics and hydrogen and oxygen isotopes. The study reveals that the stratigraphic structures in the area consist of four layers: a Holocene transgressive layer, a continental confining bed from the late Pleistocene, a Cangzhou transgressive layer from the late Pleistocene, and a fluvial aquifer from the middle Pleistocene. All aquifers in the study area have been infiltrated by modern seawater, with the uppermost Holocene aquifer influenced by evaporation and leaching processes, the central late Pleistocene aquifer remaining relatively stable, and the lower middle Pleistocene aquifer affected by subsurface low salinity runoff and exhibiting an increasing trend with depth. Given the presence of numerous hydrogeological environments globally that are similar to the study area, the obtained mechanisms of groundwater salinization in this study will provide theoretical support for groundwater management in similar regions worldwide. [ABSTRACT FROM AUTHOR]

Soil enzyme activity and its stoichiometry are excellent representatives of soil microorganisms' response to changing conditions, and act as a good indicator of microbial energy and nutrient demands. However, how soil enzyme activity and microbial nutrient limitation will be modified by grassland degradation is not well understood, especially in the saline‐alkaline meadow. Here, we presented how soil enzyme activity and microbial nutrient limitation shifted along a well‐characterized gradient of salinized degraded grasslands (non‐degraded, moderately degraded, and severely degraded). Our results showed soil enzyme activity was the highest in moderately degraded grasslands, which was mainly regulated by soil bacterial diversity. Soil microbial community metabolism in alkali‐saline meadow grasslands was limited by both carbon and phosphorus. Microbial carbon limitation showed a hump‐shaped pattern along the grassland degradation gradient, while microbial phosphorus limitation showed a gradually decreasing trend. Soil bacterial diversity is a key regulator of soil microbial carbon limitation, but the structure of the soil bacterial and plant community determines microbial phosphorus limitation. Taken together, our findings, taken together, provide evidence that soil bacteria are direct drivers of soil enzyme activity and microbial nutrient limitation along a grassland degradation gradient with salinization and suggest that these changes are regulated by soil salinity. [ABSTRACT FROM AUTHOR]

Coastal areas have made substantial contributions to global economic development but are plagued by challenges such as groundwater salinization. Groundwater serves as the primary source for drinking, industrial, and domestic purposes in these coastal areas. Therefore, understanding the causes and processes of groundwater salinization holds paramount significance for effective groundwater management. The coastal area of Laizhou Bay in northern China serves as a quintessential example of such a scenario. With substantial groundwater extraction and severe groundwater salinization issues, it exacerbates the disparity between water-resource supply and demand. Currently, our understanding of the processes and influencing factors related to groundwater salinization in this region remains limited. In this study, employing hydrochemical and stable chlorine isotope analyses on 35 groundwater and seawater samples, an in-depth investigation into the complex mechanisms underlying groundwater salinization in the Quaternary aquifers of the eastern coastal plain of Laizhou Bay was conducted. The test results of the samples indicate that brine and saline groundwater are primarily of the Na-Cl type, exhibiting a hydrochemical composition similar to that of seawater. Brackish groundwater exhibits a diverse hydrochemical composition. The hydrogen and oxygen isotope characteristics of brackish and fresh groundwater resemble atmospheric precipitation, while brine, seawater, and saline groundwater show hydrogen and oxygen isotope depletion. Compared to seawater, brine exhibits significant δ37Cl depletion. The analysis of the test results reveals that the formation of brine aquifers results from a complex interplay of climate change, tectonic movements, and sea–land evolution, involving lagoon development during seawater regression, salt concentration through evaporation, and subsequent water–rock interactions. The genesis of saline groundwater involves a complex interplay of brine–seawater mixing, significant evaporation, and potential input of fresh groundwater from atmospheric precipitation and river sources. The formation of brackish groundwater is predominantly influenced by atmospheric precipitation, and agricultural activities, with significant variations in NO3− concentrations attributed to varying intensities of fertilizer application in the northern plain area. These insights contribute to a deeper understanding of the origins of groundwater and can inform the development of policies for groundwater protection in this area. [ABSTRACT FROM AUTHOR]

The salinity of groundwater in Qinzhou Bay has been increasing since 2013. This phenomenon affects livelihoods and the local agricultural economy, specifically in the Longmengang area. In this work, we investigate the causes of water salinization to provide evidence for effectively managing the local water resources and improving water quality. We collected 110 samples of water from spatially distributed local wells, rivers, reservoirs, and the sea, and conducted a hydrochemical study complemented by numerical modeling. We found that water pumping and mariculture practices are the principal contributors to seawater intrusion into the groundwater table, which leads to increased water salinization. Plain Language Summary: Groundwater salinity in Qinzhou Bay is increasing due to excessive well water extraction and mariculture practices, which promote seawater intrusion into the local groundwater table. Based on the hydrochemical analyses, the spatially distributed trend of ions content in groundwater shows low concentrations inland and increasing concentrations seaward. However, several localities of Qinzhou Bay are out of this scenario because of artificial activities requiring specific monitoring and regulation. Key Points: Field investigations and hydrochemical analyses show salinization of groundwater in Qinzhou BayHydrogeological modeling indicates that different processes contribute to water salinizationGroundwater salinization in Longmen Island is caused by excessive groundwater use and mariculture practices [ABSTRACT FROM AUTHOR]

Under the pressure of SDG15.3.1 compliance, it is imperative to solve the land salinization degradation problem in the Yellow River Basin as China's granary. From the view of geographical scale, six zoning units were divided in the Yellow River Basin with 'climate-meteorology-geomorphology' as the main controlling factor, and a salinization inversion model was constructed for each zoning unit. Appropriate surface parameters were selected to construct a three-dimensional feature space according to the individual geographical zones. Based on the cloud data processing capability of the Google Earth Engine platform, a feature space inversion process was applied for automatic inversion of salinization. Salinization distribution maps of the Yellow River Basin in 2015 and 2020 were obtained at 30 m resolution by classifying the salinization inversion result. The distribution and spatiotemporal variation of salinization as well as the causes of salinization were analyzed. Reasonable prevention and control suggestions were subsequently proposed. This study could also be scaled up to larger and more complex geographical regions. [ABSTRACT FROM AUTHOR]

Salinization in frozen soil has posed a serious threat to the emergence and growth of crops in the next growing period. It is of great importance for the accurate detection of the content and composition of soil salt during the freeze-thaw period. Fortunately, the spectral data can be used to monitor the soil salinity during the crop growing period, particularly for the soil under an unfrozen state. However, the monitoring models under the unfrozen state cannot suitable for the frozen soil, due to the variation in the soil reflectance during freezing. In this study, an inversion model was established for the soil water-soluble salt ions in the frozen state using hyperspectral technology. A systematic analysis was made to compare the accuracy of the model in the frozen and unfrozen states. The soil samples were first collected with different salinity gradients from the Jiefangzha Irrigation Area of Hetao Irrigation District in the Inner Mongolia of China. The contents of major water-soluble salt ions (i.e., HCO3-, Cl-, CO32-, SO42-, K+, Na+, Ca2+, and Mg2+) were then measured in the unfrozen soil. The hyperspectral reflectance of soil samples was also measured by the ASD FieldSpec 3 instrument. Secondly, the soil samples were then frozen at -15°C for 12h. After that, the above-mentioned hyperspectral reflectance and ion contents were measured once again after freezing. The raw spectral data was also processed using standard normal variable (SNV) for the subsequent model construction, in order to make the hyperspectral curves smoother. Thirdly, two-thirds of the soil samples were used for the modeling (n = 78), while one-third for the validation (n = 39). The concentration gradient method was utilized to ensure the statistical characteristics of the modeling and the validation sets resembled that of the whole sample set. At the same time, the sensitive spectral intervals of each water-soluble salt ion were selected using variable importance in projection (VIP). The hyperspectral inversion model was formulated for the major water-soluble salt ions content with the sensitive spectral bands using partial least squares regression (PLSR), support vector regression (SVR), and extreme learning machine (ELM). Finally, the performances of these models were evaluated by the determination coefficient of calibration sets (RC 2), determination coefficient of prediction sets (RP 2), root mean square error (SRMSE), and residual predictive deviation (SRPD). The results showed that the VIP hyperspectral monitoring model managed to invert the most content of the water-soluble salt ions in the frozen soil, but the inversion accuracy of different ions varied greatly. Among them, the prediction accuracies of Cl-and K+ were extremely high with an RPD of above 2.5. There was a reasonably good prediction accuracy of SO42-, Ca2+, and Na+ (2.0

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Copyright of Hydrogeology & Engineering Geology / Shuiwendizhi Gongchengdizhi is the property of Hydrogeology & Engineering Geology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

China's Yellow River Delta represents a typical area with moist semi-humid soil salinization, and its salinization has seriously affected the sustainable use of local resources. The use of remote sensing technology to understand changes in the spatial and temporal patterns of salinization is key to combating regional land degradation. In this study, a feature space model was constructed for remote sensing and monitoring land salinization using Landsat 8 OIL multi-spectral images. The feature parameters were paired to construct a feature space model; a total of eight feature space models were obtained. An accuracy analysis was conducted by combining salt-loving vegetation data with measured data, and the model demonstrating the highest accuracy was selected to develop salinization inversion maps for 2015 and 2020. The results showed that: (1) The total salinization area of the Yellow River Delta displayed a slight upward trend, increasing from 4244 km2 in 2015 to 4629 km2 in 2020. However, the area's salting degree reduced substantially, and the areas of saline soil and severe salinization were reduced in size; (2) The areas with reduced salinization severity were mainly concentrated in areas surrounding cities, and primarily comprised wetlands and some regions around the Bohai Sea; (3) Numerous factors such as the implementation of the "Bohai Granary" cultivation engagement plan, increase in human activities to greening local residential living environments, and seawater intrusion caused by the reduction of sediment contents have impacted the distribution of salinization areas in the Yellow River Delta; (4) The characteristic space method of salinization monitoring has better applicability and can be promoted in humid-sub humid regions. [ABSTRACT FROM AUTHOR]

Cenozoic fine‐grained sedimentary rocks in the southwestern Qaidam Basin, as typical salinized lacustrine sediments, are significantly different from those in other freshwater lakes under the impact of the high salinity in the lake. Many fine‐grained sedimentary rock samples were selected from the lower member of Neogene (N1) in the Gaskule Oilfield, Qaidam Basin, northwest China, with the aim to analyze and test their petrology, pore structure, and organic geochemical characteristics and determine its genesis and geological significance. Based on previous results, a new genesis of mixed sedimentary rocks is proposed. The Cenozoic lacustrine fine‐grained sedimentary rocks in SW Qaidam Basin belong to mixed sedimentary rocks, which can be divided into three types, including carbonate and terrigenous clastic‐bearing mudstone, carbonate‐bearing to terrigenous clastic mixed sedimentary rocks, and carbonate‐terrigenous clastic mixed sedimentary rocks. The geneses of mixing are quite different from that of mixed marine rocks. According to the sedimentary characteristics of the salinized lakes, three new geneses of mixed deposits are proposed: syn‐sedimentary mixing, varve interbedded mixing, and biogenic mixing. The reservoir spaces of the Cenozoic lacustrine fine‐grained sedimentary rocks in SW Qaidam Basin include residual intergranular pores, intercrystalline pores, microfractures, and minor dissolved pores. The reservoirs have super‐low porosity and ultra‐low permeability, with a porosity of 1.82%–21.04%, averaging 7.71%, and permeability of (0.0028–254.86) × 10–3 μm2, averaging 2.82 × 10–3 μm2. The test results of total organic carbon (TOC) content show that the highest content of organic carbon reached 1.41%, and those of vitrinite reflectance show that Ro ranges from 0.525%–0.824%, with an average of 0.806%. The organic geochemical characteristics show that the fine‐grained mixed sedimentary rocks of SW Qaidam Basin have the potential for self‐generation and self‐storage. As an unconventional reservoir, it has potential industrial value. This is the first study of fine‐grained sedimentary rocks in the Qaidam Basin, which offers certain theoretical and practical values. [ABSTRACT FROM AUTHOR]

Gypsum can be one of the by-products of the wet Flue Gas Desulfurization (FGD) process in coal-fired power plants. FGD gypsum can also be widely expected to ameliorate the saline-alkali soil in recent years. In this study, suitable application of desulphurized gypsum to improve the yield of sunflower in saline soil of Hetao irrigation area was selected from three applications of desulphurized gypsum. A field experiment was carried out with three applications (hole, strip, and spread) of FGD gypsum in the Hetao Irrigation District of Inner Mongolia (108°11′ east longitude and 41° 02′ north latitude). The optimal application was determined for the more efficient and low-cost soil amelioration. The treatment without FGD gypsum was also used as the control. Soil samples were collected after the first season of sunflower harvest, with a depth of 100 cm and 20 cm increments at the sites of the sunflower planting strip and the center of small row spacing. An investigation was also made on the effects of different applications of FGD gypsum on the soil pH, Electrical Conductivity (EC), and water-soluble cations distribution in the soil profile. The results showed that the three applications of FGD gypsum significantly reduced the soil pH and Sodium Adsorption Ratio (SAR) in the topsoil (0-20 cm), whereas, there was an increase in the concentration of water-soluble cations and the soil EC, compared with the control. The topsoil pH and SAR in the strip application were 20% and 41% lower, while the EC and water-soluble Ca2+ concentrations were 44% and 509% higher than that in the control, respectively. The concentration of water-soluble ions decreased gradually, with the increase of soil depth. However, the concentrations of water-soluble Ca2+ increased by 47%-105% at the 80-100 cm soil layer in the FGD gypsum application. In addition, the concentrations of water-soluble Na+ at the 20-100 cm soil layer in the three FGD gypsum applications were higher than that in the control, resulting in an increase in SAR. The effects of strip and hole on the saline-alkali soil amelioration were greater than that at the center of small row spacing, while there was no significant difference between the two sampling sites in the spread treatment. The three applications of FGD gypsum significantly increased the emergence rate and yield of sunflower, where the highest yield of sunflower was obtained from the strip treatment. Therefore, the effective components under the FGD gypsum strip can be concentrated around the sunflower roots to ameliorate the saline-alkali soil in the Hetao Irrigation District of Inner Mongolia in China. [ABSTRACT FROM AUTHOR]

Climate change has given rise to salinization and nutrient enrichment in lake ecosystems of arid and semiarid areas, which have posed the bacterial communities not only into an ecotone in lake ecosystems but also into an assemblage of its own unique biomes. However, responses of bacterial communities to climate-related salinization and nutrient enrichment remain unclear. In September 2019, this study scrutinized the turnover of bacterial communities along gradients of increasing salinity and nutrient by a space-for-time substitution in Xinjiang Uyghur Autonomous Region, China. We find that salinization rather than nutrient enrichment primarily alters bacterial communities. The homogenous selection of salinization leads to convergent response of bacterial communities, which is revealed by the combination of a decreasing β-nearest taxon index (βNTI) and a pronounced negative correlation between niche breadth and salinity. Furthermore, interspecific interactions within bacterial communities significantly differed among distinct salinity levels. Specifically, mutualistic interactions showed an increase along the salinization. In contrast, topological parameters show hump-shaped curves (average degree and density) and sunken curves (modularity, density, and average path distance), the extremums of which all appear in the high-brackish environment, hinting that bacterial communities are comparatively stable at freshwater and brine environments but are unstable in moderately high-brackish lake. [ABSTRACT FROM AUTHOR]

Secondary salinization is a serious environmental issue and a major threat to the sustainable use of grasslands. Information about the response of microbial communities and soil properties in already saline soils to increasing salinity is lacking. We investigated soil properties and the structures of soil bacterial and fungal communities across a gradient of salinization in the Horqin Grassland, China. Three sites with relatively lightly (average soluble salt content = 0.11%), relatively moderately (average soluble salt content = 0.44%), and heavily (average soluble salt content = 1.07%) degraded grassland, were selected as experimental sites. We examined variations in the composition and structure of the soil bacterial and fungal communities by using high-throughput sequencing of the 16S and 18S rRNA genes, respectively. We found degrading effects of salinization on soil properties, i.e., decreased soil moisture, organic matter, total N, NH4-N, and NO3-N and increased soil bulk density, pH, and electrical conductivity. The bacterial and fungal community structures changed with increasing salinity. However, dominant microbial taxa (including phylum, genus, and operational taxonomic unit levels) were similar among experimental sites, indicating that increasing salinization slightly affected the basic compositions of microbial communities in already saline grasslands. Furthermore, the relative abundances of most dominant taxa sensitively responded to the soil salt content. Acidobacteria, Actinobacteria, Chloroflexi, RB4, Rubrobacter, Blastocatella, H16, Glomeromycota, and Aspergillus linearly increased with increasing salinization, suggesting that they could be used as bioindicators for salt-tolerant communities. Overall, the changes in the structures of soil bacterial and fungal communities were determined by the relative quantities of dominant taxa rather than community composition. The structures of soil bacterial and fungal communities were linked to soil properties and vegetation. Increasing soil salt content, and thereby varied pH and organic matter, were likely the direct influencing factors of microbial communities in these saline grasslands. [ABSTRACT FROM AUTHOR]

• Denitrification and DNRA contributed more to N transformation than anammox. • Salinity increase shifted nitrate reduction regime from denitrification toward DNRA. • Both C/N ratio and sulfide content are the important factors partitioning the shift. Salinization in estuarine wetlands significantly alters the balance between their nitrogen (N) removal and retention abilities but these processes have not yet been characterized effectively. In the present study, the potential rates of sediment denitrification, anaerobic ammonium oxidation (anammox), and dissimilatory nitrate reduction to ammonium (DNRA) were mapped using N isotope tracing methods along salinity gradients across the Yellow River Delta wetland (YRDW) in China. The contribution of anammox to total dissimilatory N transformations in YRDW was merely 6.8%, whereas denitrification and DNRA contributed 52.3% and 40.9%, respectively. The potential rate of denitrification (5.82 μmol/kg/h) decreased significantly along salinity gradients and markedly exceeded DNRA potential rate (2.7 μmol/kg/h) in fresh wetlands, but was lower than that of DNRA in oligohaline wetlands (3.06 and 3.18 μmol/kg/h, respectively). Moreover, a significantly positive relationship between salinity and DNRA/denitrification was obeserved, indicating that increased salinity may favor DNRA over denitrification. Furthermore, total sulfur (TS) content and ratio of total organic carbon to total nitrogen (C/N) increased with the salinity gradient and showed evident positive relationships with the DNRA/denitrification ratio. In this study, we proved that increased salinization resulted in the dominance of DNRA over denitrification, possible through the addition of S and alteration of the C/N in estuarine wetlands, leading to increased N retention in estuarine wetlands during salinization, which would enhance the eutrophication potential within wetlands and in downstream ecosystems. [Display omitted] [ABSTRACT FROM AUTHOR]

Microorganisms can adapt to the salinity by ingesting energy, further to synthesize organic osmolytes in soil. However, microbial demand for energy may change, as the soil salinity changes. In this study, a field experiment was carried out to explore the effects of the combined application of organic and inorganic fertilizers on soil respiration and microbial biomass in saline soil. The samples were taken as the mild saline soil, S1 (electrical conductivity (EC) 0.46 dS/m) and moderate saline soil, S2 (electrical conductivity (EC) 1.07 dS/m) in Hetao Irrigation District of Inner Mongolia, China, in 2018. Soil respiration rate was measured by a li-8100 soil carbon flux automatic measurement system. Surface soil samples of 0-20 cm depths were collected under various fertilization regimes in mild and moderate saline soil. Calcium chloride and chloroform fumigation extraction were used to investigate the effect of various fertilization regimes on the mineral nitrogen contents and microbial biomass in soil. Six treatments were set, including no fertilization (CK), urea (U1), and 25%, 50%, 75%, as well as 100% of urea N substituted by organic fertilizers U3O1, U1O1, U1O3, and O1, respectively, during the second growing season (April-September). The parameters were measured under equal N application rates of 240 kg/hm2, the dynamics of soil microbial biomass (i.e., microbial biomass carbon [MBC] and microbial biomass nitrogen [MBN]), and soil respiration (i.e., soil respiration rate, soil autotrophic respiration rate, and soil heterotrophic respiration rate). The results showed that the contents of mineral nitrogen in S1 soil were higher in the U1 treatment during the early growing stage (seedling and stem elongation stage), but higher in the U1O1 treatment in the later stage. S2 soil showed that the soil mineral nitrogen contents were higher in the whole growing stage, as the application rate of organic fertilizer increased. Furthermore, the increase of soil salinization resulted in the decrease of microbial biomass and microbial activity in the soil. The MBC in S2 soil decreased by 12.01%-68.81%, while the MBN decreased by 14.31%-58.58%, and the soil respiration flux decreased by 11.75%-54.71%, compared with S1 soil. Furthermore, the organic fertilizer significantly increased the microbial biomass and microbial activity under different degrees of saline soils. The S1 saline soils treated with U1O1 presented the higher MBC, MBN, and soil respiration flux, indicating a significant increase by 48.44%, 42.50%, 31.74%, respectively, compared with U1 treatment (P<0.05). The performance of S2 saline soil after the O1 treatment was better than that after the U1 treatment, where the MBC, MBN, and soil respiration flux increased by 68.07%, 48.99%, 45.19%, respectively (P<0.05). The highest corn yield was also achieved in the S1 and S2 soil treated with U1O1 and O1, which were 11 902.91, and 7 609.67 kg/hm², respectively. A correlation analysis was found that the soil respiration presented a significant positive correlation with the MBC and MBN (P<0.05). The soil temperature and mineral nitrogen had a significant positive correlation with the soil respiration, MBC, and MBN (P<0.05). Regression analysis showed that there was a significant exponential relationship between the soil respiration and temperature, (P<0.05), but the relationship between soil respiration rate and soil moisture content was not significant. Additionally, there was a significant nonlinear relationship of soil microbial biomass and respiration rate with the organic fertilizer rate and soil salt concentration. The regression coefficient demonstrated that the appropriate organic fertilizer rate contributed to maximizing the soil microbial biomass and respiration rate in different saline soils. Optimal organic and chemical fertilizer management models were achieved for the mild saline soil in the Hetao irrigation area. Specifically, the mild saline soil (120 kg/hm² urea+120 kg/hm² organic fertilizer), and moderate saline soil (240 kg/hm² organic fertilizer) can be expected for the higher corn yield under the improved soil microbial environment. [ABSTRACT FROM AUTHOR]

The Yellow River Delta is the largest and youngest estuarine and coastal wetland in China and is experiencing the most active interactions of seawater and freshwater in the world. Bacteria played multifaceted influence on soil biogeochemical processes, and it was necessary to investigate the intermodulation between the soil factors and bacterial communities. Soil samples were collected at sites with different salinity degree, vegetations, and interference. The sequences of bacilli were tested using 16S rRNA sequencing method and operational taxonomic units were classified with 97% similarity. The soil was highly salinized and oligotrophic, and the wetland was nitrogen-restricted. Redundancy analysis suggested that factors related with seawater erosion were principal to drive the changes of soil bacterial communities and then the nutrient level and human disturbance. A broader implication was that, in the early succession stages of the coastal ecosystem, seawater erosion was the key driver of the variations of marine oligotrophic bacterial communities, while the increasing nutrient availability may enhance in the abundance of the riverine copiotrophs in the late stages. This study provided new insights on the characteristics of soil bacterial communities in estuarine and coastal wetlands. [ABSTRACT FROM AUTHOR]

Important geological events that influenced the global environment occurred during the mid‐Cretaceous period. Dramatically increasing temperatures not only triggered oceanic anoxic events (OAEs) but also led to the aridity of terrestrial environments in East Asia. This study provides evidence for the aridity of a terrestrial East Asian environment during the mid‐Cretaceous and provides an example of the influence of the Cretaceous greenhouse climate on a terrestrial lake system in correspondence with the OAE 1a event. Palaeosalinity indexes (B, B/Ga, Sr/Ba, and Couch's palaeosalinity) and palaeoclimate proxies (Sr/Cu, Rb/Sr, Al2O3/MgO, and clay mineral compositions) of shale and mudstone from the Laiyang Group of the Jiaolai Basin in Eastern China were analysed. The results demonstrate that the palaeoclimate in the Wawukuang Formation was relatively warm and humid but became extremely dry and hot in the Shuinan Formation during the OAE 1a event before becoming warm and humid again in the Longwangzhuang and Qugezhuang formations. As a result, the palaeosalinity of the Jiaolai Basin increased from 4% in the Wawukuang Formation to 30% in the Shuinan Formation before decreasing to 0.48% in the Longwangzhuang and Qugezhuang formations. The following conclusions are from combining the distributional characteristics of the saliferous strata and its palaeontology, the palaeogeographic background, and the aeolian sandstone in eastern China. (a) The East Asian continental margin was influenced by the Cretaceous greenhouse climate, which resulted in the salinization of the Jiaolai Basin. (b) The significant increase of the palaeosalinity in the Shuinan Formation was an effect of the OAE 1a event on the terrestrial lake system, which further suggests the OAE 1a event was global. (c) Influences of the hothouse climate on the continental lakes changed the palaeosalinity of the water bodies. [ABSTRACT FROM AUTHOR]

Using natural tracer profiles to study migration of porewater salinity can help determine fluid fluxes and the timescales of salinization and freshening in coastal regions. Saline groundwater associated with evaporation and transgression events is widely distributed in the North China Plain (NCP). However, the fluid flux, time scales, and importance of different salinization processes are poorly constrained, particularly in areas beyond the limit of marine influence. Chloride (Cl) and δ18O profiles were obtained from two boreholes: one drilled at the edge of the piedmont alluvial fan (HS borehole) and one in the coastal region (G1 borehole). Numerical simulation of Cl and δ18O profiles confirmed diffusion‐dominated solute transport but also indicated slow upward advective flow over geological timescales. The profile modeling at HS indicated that salinization related to evaporation has occurred since the Late Pleistocene. Assessment of alternative conceptual models indicates that intensive groundwater pumping in recent decades has also caused significant downward movement of saline porewater (e.g., movement of brackish water at ~0.6 m/yr), mixing modern or Holocene water with Pleistocene water. The coastal Cl profile modeling in contrast shows that porewater salinity can be primarily attributed to salt diffusion during four transgression/regression cycles since the late Middle Pleistocene. The Cl transport appears never to have reached an equilibrium state during the glacial‐interglacial cycles. This suggests not only that trapped Holocene seawater is still present and leaching into adjacent sediments but also that Pleistocene water has never been entirely flushed from the deep part of the coastal sediments. Key Points: Mechanisms and timescales of salinization/freshening processes were studied in coastal region where marine and nonmarine sources coexistDiffusion dominated migration of porewater salinity affected by upward advection and downward flow caused by intensive pumpingPleistocene water has never been entirely flushed from coastal sediments during glacial‐interglacial cycles [ABSTRACT FROM AUTHOR]

Overexploitation of groundwater has resulted in seawater intrusion in many semiarid and arid coastal areas. This study illustrates the origin of groundwater salinity and assesses seawater intrusion/extrusion process in the Yang-Dai River plain aquifer, by analyzing hydrochemical and stable isotopic compositions of surface water, groundwater, geothermal water, and seawater. A cone of depression in groundwater is caused by intensive groundwater pumping formed in the late 1980s in the alluvial Yang-Dai River plain. In the northern part, groundwater exploitation has caused seawater intrusion identified by Ca-Cl type water. However, the widely distributed silty clay prevented the seawater intrusion in the southern part, evidenced by Ca-HCO3 type water with depleted δ2H (−60 to −46‰) and δ18O (−8.9 to −4.7‰). Anthropogenic pollution also plays a significant role in groundwater salinization. The positive correlation between Cl and NO3- for most groundwater and the extremely high nitrate concentrations (up to 652.7 mg/L) indicate that fertilizer from agricultural activities has greatly influenced groundwater quality. Irrigation return flow evaporation during agricultural activities also accounts for groundwater salinity. Besides the intensive fertilizer usage, seawater intrusion and the established anti-tide dams reduced the surface water and groundwater discharge to the sea and then resulted in the extremely high nitrate concentration. This study may improve the understanding of the groundwater salinization processes in a complex coastal aquifer, which is greatly influenced by anthropogenic activities. [ABSTRACT FROM AUTHOR]

The sedimentary background and sedimentary environment of the Lower Cretaceous of Lingshan Island, Shandong, remain unclear. There is considerable controversy as to whether the sedimentary environment was marine or continental. In this study, analyses were conducted with respect to indicators of paleosalinity, the chemical composition of clay, paleobiota, the characteristics of strata exhibiting salinization in eastern China during the Early Cretaceous, and the relationship between paleosalinity and paleoclimate. The results indicate that the sedimentary environment of the Lower Cretaceous Laiyang Group of Lingshan Island was that of a salified lake rather than a marine environment. This study not only provides a reference for determining the sedimentary environment of the Lower Cretaceous Laiyang Group of Lingshan Island but also offers a new perspective for the study of Cretaceous strata with salinization characteristics in eastern China. [ABSTRACT FROM AUTHOR]

Land salinization is one of the most common land degradation processes. Tongyu county exemplifies all the forms of land degradation in Northeast China and is prone to land salinization due to its fragile physical conditions. In this study, Landsat remote sensing images are adopted to invert surface albedo, MSAVI (modified soil adjusted vegetation index), and salinity index (SI) data. The feature space models of albedo-SI and MSAVI-SI, considering the bare soil and vegetation information respectively, are constructed and compared. Land salinization changes for the period of 1998–2017 are investigated using the salinization monitoring index (SMI) and salinization detection index (SDI) extracted from the feature space models. Our results show that the land salinization situation in Tongyu county have tended to improve, associated with the biological, ecological and engineering means for the degraded land rehabilitation. The feature space models is applicable for the extraction of salinization information, and albedo-SI may evaluate land salinization levels with higher accuracy. [ABSTRACT FROM AUTHOR]

The construction of transportation corridors (such as roads) frequently disturbs and alters the natural disturbance regimes of ecosystems in many areas worldwide. In this study, by comparing the species richness, diversity, composition and soil among four ecotypes (non-road disturbance areas, road systems without ditches, road systems with large and small ditches), we tested the hypothesis that the presence of road ditches could facilitate the preservation of species and increase species richness in the Yellow River Delta, China. Both positive and negative effects of road ditches on the plant community were detected. The species richness in road systems (> 14) was significantly greater than that in the non-road disturbance areas (6). In the road systems without ditches, the refuges (relatively low soil salinity: 1.12 ± 0.15 mg/g) for non-halophytes were limited to road verges (0 m from a road verge). In the road systems that included a ditch, however, the refuge area expanded from road verges to 30 m from the verges. The width and structure affected ditch function. Both large ditches and small ditches effectively reduced the salinity of the soil, but the influence mechanisms differed, resulting in differences in the distribution of species diversity. The proportion of non-halophytes was significantly greater (37%) in the road systems with large ditches than in the road systems with small ditches (45.0%). In addition, the proper structure of large ditches with slopes increased the species diversity (the species richness was 26); in contrast, some structures of small ditches reduced the species diversity (the species richness was 14). The results of our study suggest that large ditches (width > 5 m) can be constructed 10 m from road verges to increase local species richness. Moreover, it is necessary to create buffer zones alongside roads (30 m from road verge), which can prevent the movement of invasive species into internal natural areas. [ABSTRACT FROM AUTHOR]

Plateau lakes characterized by salinization and eutrophication are essential aquatic ecosystems. A myriad of microorganisms serve as crucial biological resources in plateau lakes and drive the elemental cycles of these ecosystems. Currently, there is a paucity of knowledge regarding the impacts of salinization and eutrophication dynamics on the microbiota in plateau lakes. Here, high-throughput sequencing of the 16S ribosomal RNA genes (V4 region) was used to characterize microbial community structure and assembly in plateau lakes with different salinities and trophic levels. Water samples were collected at 191 sites across 24 lakes on the Qinghai-Tibet and Inner Mongolia Plateaus in northern China. The results showed that high salinity considerably reduced microbial alpha-diversity and niche breadth while increasing within-group similarity among various lake types. High salinity additionally decreased the complexity of microbial networks and enhanced network robustness. The assembly of microbial communities was primarily governed by deterministic processes in high-salinity and eutrophic low-salinity lakes. At decreased salinity, trophic level played a leading role in shaping microbial community structure, and the ecological processes shifted from deterministic processes driven by high salinity to eutrophication-driven deterministic processes. The biomarkers also varied from taxa adapted to high-salinity environments (e.g., Nanoarchaeaeota, Rhodothermia) to those suited for living in freshwater and low-salinity habitats (e.g., Alphaproteobacteria, Actinobacteria). In the case of eutrophication, Actinobacteria, Chloroflexi, and Cyanobacteria became the dominant taxa. Our findings indicate that decreased salinity enables trophic level to play an enhanced role in shaping microbial community structure and assembly in plateau lakes. This study enriches our knowledge about the ecological impacts of salinization and eutrophication in plateau lakes., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Saline soil is widely distributed in western Jilin province, China, agriculture and engineering are affected by the saline soil. Its formation and development process are influenced the most by factors of the natural geological environment. For the purpose of investigating the salinization process and influence factors in western Jilin, this study analyzes the saline soil of Nong'an in western Jilin Province, which was sampled during a field investigation. Thereafter, the characteristics of the water and salt migration in the soil have been investigated in the laboratory, the environmental factors of the study area, and the influence of the ecological environment on salinization have also been discussed. The results show that the water and salt migrate with seasonal changes in soil. The water content is low in autumn, and high in spring and summer. The salt content of the soil near the ground surface is low in autumn, and high in spring and summer, meanwhile, the salt content in the deep soil layers is low in spring and autumn, and high in summer. During both the unfrozen period and the frost-thawing periods, the soil salinization continues to enhance, and salinization eventually causes land desertification. This study can provide the theoretical basis for the protection of fragile ecological environments. [ABSTRACT FROM AUTHOR]

Soil salinization is a global issue of concern and the biggest global natural disaster. Salt-affected soil is also the most prominent environmental problem in arid and semi-arid regions in China. In this study, the Keriya Oasis in the arid zone of Xinjiang, Northwestern China was chosen as study area, a geodatabase was created with multiple field observations together with laboratory analyses and related datasets including attribute, vector and raster data. Topsoil electrical conductivity (TS_EC) was selected as the ecological endpoint for evaluating the salinization risk. And 14 evaluation indicators were chosen as the main sources of soil salinity risk which included ground evapotranspiration (ET), land surface temperature (LST), surface albedo (Albedo), digital elevation model (DEM), normalized difference vegetation index (NDVI), leaf area index (LAI), aboveground biomass (Biomass), groundwater depth (GWD), groundwater electrical conductivity (GW_EC), topsoil water content (SWC), topsoil pH value (pH), land use land / cover type (LULC), population density (PD) and per capita arable land (PCAL). An index system for soil salinization risk assessment was established. Through remote sensing (RS) techniques and quantitative inversion, 7 risk factors were derived such as: NDVI, LAI, Albedo, LST, ET, Biomass, DEM; the other factors were spatially interpolated, then data normalization was applied to all these datasets and overlayed GIS database of soil salinity risk factors was built. Risk weights of evaluation factors were determined and weight coefficients were calculated by adopting Pearson correlation analysis method. The theory of grey relational analysis system was introduced into soil salinization risk assessment, and risk assessment model was constructed in the study area. Then the soil salinity risk of the region was quantitatively assessed and classified, and finally soil salinity risk map was elaborated. The results showed that: the salinization risk values of the whole study area varied from 0.053 to 0.747, with a mean value of 0.190. Spatial distribution heterogeneity of different risks in the Keriya Oasis was prominent, and soil salinity risk was mainly demonstrated moderate risk. The area of risk rating 3 was the largest, and it accounted for 48.94% of total study area, soil salinity risk was moderate, belonging to potential risk area; The area of rating 4 accounted for 27.69%, and it belonged to the low risk region. Rating 2 risk region accounted for 19.35%, and soil salinity risk was relatively high. Rating 1 risk area accounted for only 4.02%, but it was characterized with very high risk soil salinity. Although the high risky area was smaller in size, it might lead a negative influence on the ecological environment and agricultural production in the northern region of the oasis. In conclusion, the quantitative assessment and mapping results of soil salinization risk in Keriya Oasis could be used to make appropriate decisions related to crop production, prevention of soil salinization, and it might offer scientific evidence and consulting for obtaining sustainable development of agriculture and eco-environment in arid and semi-arid regions. [ABSTRACT FROM AUTHOR]

Abstract Rammed earth, a kind of building materials used worldwide because of its straightforward manufacture and low cost, is still used in the construction industry today. Many rammed earth architectural relics are preserved in the arid and semi-arid areas in northwest China. In this area, the winter snowfall process is generally long and may work to degrade the physical and mechanical properties of rammed earth, destroying these relics. Therefore, to protect rammed earth sites, it is very important to understand the mechanisms governing rammed earth deterioration during snowfall. Using real-time monitoring and soluble salt testing of the temperature and water content of the rammed earth at three representative sites in the north-west region, we found that snowfall leads to varying degrees of freeze-thaw cycle and salinization coupling that degrade rammed earth structures. Wind erosion, disintegration, shear and mercury intrusion experiments using remoulded rammed earth samples were performed based on the monitoring results and incorporated different types and concentrations of soluble salts; three freeze-thaw cycles were applied to explore the macro and micro changes in the wind erosion modulus, disintegration speed, cohesion, internal friction angle and pore size of the rammed earth samples. Finally, the joint analysis of the monitoring results, macroscopic property indices and microscopic property indices revealed the mechanisms of rammed earth degradation due to the observed coupling effect. Highlights • The snowfall in different seasons would make different parts of earthen sites experienced different freeze-thaw and salt coupling effects. • The upper and lower limits of freeze-thaw temperature, and the durations of freeze and thaw were obtained. • The results of mercury injection tests showed the pore size of samples would increase under coupling effects, but the degree of coarsening and uniformization is differential. • The macroscopic index parameters have good and different types of functions with fractal dimension values, and the correlation coefficient is greater than >0.93 for all regression equations. • The coupling effects of freeze-thaw cycles and salinization due to snowfall on the rammed earth have degradation functions for earthen sites. [ABSTRACT FROM AUTHOR]

The purpose of the study was to improve the pertinence and accuracy of salinization monitoring and control. The main data sources for this paper include agricultural land classification database, 1:500 000 spatial distribution data of saline-alkali land, China earth international exchange station climate data daily value sata set (V3.0), 1:1 000 000 soil database data, 1:1 000 000 spatial distribution data of soil texture in China, land change survey database and other data of Heilongjiang Province. With the support of the above data, on the one hand, research starts from the connotation of land salinization, filtered out land risk assessment factor from numerous factors, include landform, soil texture, evaporation and precipitation ratio, groundwater mineralization, regional sensitivity, land use level, the relationship between land salinization and its correlation was analyzed by the grey correlation model, and used the grey correlation model to analyze the correlation between these factors and land salinization, in order to verify the rationality of the selection of indicators, based on this, carry out grid training and accuracy test, formed land salinization assessment model. On the one hand, started from the extension of land salinization, screened out the resistance factors of soil salinization diffusion or migration, and constructed a resistance surface, used the minimal cumulative resistance model to evaluate the risk pattern of land salinization landscape. After the above work was completed, then with the help of ArcGIS spatial analysis function, superimposed the evaluation results of land salinization danger and land salinization landscape risk pattern, Formed land salinization type zones and monitoring levels. This paper takes Heilongjiang Province as an example to apply the method, the main research results were summarized as follows: 1) In terms of the salinity danger of the land, the land salinization danger of the salinity risk of severe and above land were mainly distributed in the southwestern part of the Songnen Plain, moderately distributed in the north-central part of the Songnen Plain and the northeastern part of the Sanjiang Plain. The light and below were mainly distributed in the great and small xing'an ridge and the southeastern mountainous areas. Eastern Songnen Plain and Southern Sanjiang Plain. 2) In terms of risk pattern, the severe and above were not only distributed in the central and northern parts of the Songnen Plain, but also in the central and northern parts of the Songnen Plain. In addition, there were also a small distribution in the northeastern and southeastern mountain areas of the Sanjiang Plain; moderately except in the Songnen Plain. The northern part and the northeastern part of the Sanjiang Plain were distributed, in the Middle and Central South of the Songnen Plain, the central and western parts of the Sanjiang Plain, and the southeastern mountain areas were also distributed; the mild and the following risk patterns were mainly distributed in the great and Small Xing’an Ridge, in addition to Sanjiang there is a small distribution on the southern edge of the plains and southeastern mountains. 3) The monitoring level of salinization in Heilongjiang Province showed the overall pattern of the west > east > central, northern and southern regions, the high-level and medium-level monitoring areas were mainly distributed in the western, southwestern, northern parts of the Songnen Plain, and the northeastern part of the Sanjiang Plain, the low-level monitoring areas were mainly distributed in the eastern part of the Songnen Plain, in the south of the Sanjiang Plain, and in the southeastern mountain areas, non-monitoring areas were mainly distributed in the large and Small Xing'an Mountains. The conclusion is that the land salinization monitoring area identification technology based on the risk and landscape ecological risk pattern takes into account the connotation of salinization and the extension of salinization, which provides scientific basis for the monitoring and prevention of land salinization. [ABSTRACT FROM AUTHOR]

The Zuli River is one of the branches of the upper Yellow River, as an inland catchment with semiarid climate in northwestern China, and the formation, evolution, and development of brackish water at such a large scale have remained unclear. This study aims to find clues about the origin and formation mechanism of salty water through multiple methods of hydrochemistry and isotope hydrology. The results show that groundwater is dominantly recharged by precipitation, and the river water was mainly recharged by groundwater discharge. The relatively high tritium content of groundwater (>5.0 TU) clearly suggests the occurrence of a modern recharge and rapid circulation. The dissolution of evaporate minerals, followed by incongruent dissolution of carbonate minerals (dolomite), constituted the main processes controlling groundwater salinization. In addition, the intense evaporation and unreasonable use of fertilizers further increase the TDS of the river, which should be the primary external mechanism of water salinization. Practitioner points: The authors aimed to find clues about the formation mechanism of salty water in an inland catchment of the Yellow River.The results of this research shows that the dissolution of dissolved minerals constituted the main processes controlling groundwater salinization. In addition, the intense evaporation and unreasonable use of fertilizers, which should be the primary external mechanism of water salinization.This work would provide a theoretical basis for government to develop rational utilization of brackish water resources in the study area, which is also significant for understanding the mechanism of water salinization in an inland mountain watershed and even in similar inland watersheds around the world [ABSTRACT FROM AUTHOR]

Although there have been obvious land use changes in Xinjiang, China, the effect of reclamation (ecological restoration) of abandoned farmlands on soil microbial properties i s rarely reported. Natural restoration of abandoned farmland was used as a control treatment, and the effects of different reclamation (ecological restoration) patterns on soil microbial properties in Shihezi, Xinjiang, China were analyzed. The results showed that there was a significant difference between different reclamation (ecological restoration) patterns in soil chemical and microbial characteristics (P < 0.05). These results indicate that the highest values for soil organic matter and available P were in accordance with the highest values for soil microbial communities (fungi, bacteria and total microbial amount), and the higher the value of pH, the lower the activity of urease and soil microbial biomass carbon. Land use patterns, both ecological restoration and reclamation types, were useful when only soil quality improvement was considered. Because of the advantages of improvement in soil fertility, the agroforestry pattern could be used as the preferred reclamation pattern for abandoned farmland in salinized regions. By increasing the soil water content and promoting the establishment of vegetation, the water recharge pattern could be a good choice during the early stage of ecological restoration of abandoned farmland. [ABSTRACT FROM AUTHOR]

Groundwater-level fluctuations at a large scale have a significant effect on the preservation and restoration of vegetation. This study determined suitable groundwater depth within which natural vegetation grows well, and analysed the effect of groundwater regulation on vegetation restoration in Tianjin City, northern China. Normal and lognormal distributions were used to fit the curve of the relation between vegetation and groundwater depth. The groundwater depth range corresponding to the higher frequency of vegetation distribution was regarded as the ‘suitable water depth’ range for vegetation growth. The suitable groundwater depth for shrub growth was 3-5 m and for grass growth 1-3 m. A groundwater flow model predicted the future changes of groundwater depths in the vegetation distribution area under the condition that the current levels of groundwater extraction are maintained. The results showed that there is potential for the extraction of groundwater in shrubland areas, but for grassland areas the water-table elevation showed a downward trend, meaning that water shortages in some areas may be more severe in the future. Finally, based on the current groundwater extraction regime, two regulation schemes were developed: (1) for shrubland, groundwater extraction was reduced by 10% in the ecological water deficit areas, and extraction was increased by 10% in the ecological water surplus and suitable areas, and (2) for grassland, groundwater recharge was increased by the restoration of the wetland areas. In conclusion, the groundwater depths in most of the area would be more suitable for vegetation growth under the regulation schemes. [ABSTRACT FROM AUTHOR]

Data on spatiotemporal variations in groundwater levels are crucial for understanding arsenic (As) behavior and dynamics in groundwater systems. Little is known about the influences of groundwater extraction on the transport and mobilization of As in the Hetao Basin, Inner Mongolia (China), so groundwater levels were recorded in five monitoring wells from 2011 to 2016 and in 57 irrigation wells and two multilevel wells in 2016. Results showed that groundwater level in the groundwater irrigation area had two troughs each year, induced by extensive groundwater extraction, while groundwater levels in the river-diverted (Yellow River) water irrigation area had two peaks each year, resulting from surface-water irrigation. From 2011 to 2016, groundwater levels in the groundwater irrigation area presented a decreasing trend due to the overextraction. Groundwater samples were taken for geochemical analysis each year in July from 2011 to 2016. Increasing trends were observed in groundwater total dissolved solids (TDS) and As. Owing to the reverse groundwater flow direction, the Shahai Lake acts as a new groundwater recharge source. Lake water had flushed the near-surface sediments, which contain abundant soluble components, and increased groundwater salinity. In addition, groundwater extraction induced strong downward hydraulic gradients, which led to leakage recharge from shallow high-TDS groundwater to the deep semiconfined aquifer. The most plausible explanation for similar variations among As, Fe(II) and total organic carbon (TOC) concentrations is the expected dissimilatory reduction of Fe(III) oxyhydroxides. [ABSTRACT FROM AUTHOR]

Salinization in coastal aquifers is usually related to both seawater intrusion and water-rock interaction. The results of chemical and isotopic methods were combined to identify the origin and processes of groundwater salinization in Daguansha area of Beihai, southern China. The concentrations of the major ions that dominate in seawater (Cl−, Na+, Ca2+, Mg2+ and SO42-), as well as the isotopic content and ratios (2H, 18O, 87Sr/86Sr and 13C), suggest that the salinization occurring in the aquifer of the coastal plain is related to seawater and that the prevailing hydrochemical processes are evaporation, mixing, dissolution and ion exchange. For the unconfined aquifer, groundwater salinization has occurred in an area that is significantly influenced by land-based sea farming. The integrated impacts of seawater intrusion from the Beibuwan Gulf and infiltration of seawater from the culture ponds are identified in the shallowest confined aquifer (I) in the middle of the area (site BBW2). Leakage from this polluted confined aquifer causes the salinization of groundwater in the underlying confined aquifer (II). At the coastal monitoring site (BBW3), confined aquifer I and lower confined aquifer II are heavily contaminated by seawater intrusion. The weak connectivity between the upper aquifers, and the seaward movement of freshwater, prevents saltwater from encroaching the deepest confined aquifer (III). A conceptual model is presented. Above all, understanding of the origin and processes of groundwater salinization will provide essential information for the planning and sustainable management of groundwater resources in this region. [ABSTRACT FROM AUTHOR]

Salinization in freshwater lakes is becoming a serious global environmental problem, especially in lakes of plateaus such as south-western plateau of China. However, limited information is available about the molecular response of freshwater hydrophytes to salinity under multiple stress. In the present study, a weighted gene co-expression network (WGCNA) was used to identify the modules of co-expressed genes in the physiological and biochemical indicators of Pistia stratiotes to determine its molecular response to salinity (NaCl) alone and when combined with cadmium (Cd). The physiological and biochemical indicators showed that P. stratiotes improved its salt tolerance by enhancing photosynthetic abilities, reducing oxidative stress, and inducing osmoprotectant generation. Morever, addition of NaCl reduced the Cd accumulation in P. stratiotes. Transcriptome and WGCNA analysis revealed that the pathways of alpha-linolenic acid metabolism, ribosomal, flavonoid biosynthesis, and phenylpropanoid biosynthesis were significantly enriched in both treatments. Genes associated with photosynthesis-antenna proteins, nitrogen metabolism, and the acid cycle pathways were only expressed under salinity stress alone, while the proteasome pathway was only significantly enriched in the combined salinity and Cd treatment. Our findings provide novel insights into the effects of salinization on aquatic plants in freshwater ecosystems and the management of aquatic ecosystems under global change. [Display omitted] • Molecular response of Pistia stratiote to salinity and Cd stress was studied • The addition of NaCl reduced Cd toxicity of P. stratiotes • Key pathways response to salinity and Cd stress were identified • The proteasome pathway was first identified • The species has the potential for the phytoremediation of Cd-contaminated salinity [ABSTRACT FROM AUTHOR]

The linkage between marine transgression and lacustrine source rock development has been highlighted for decades. Here, improved understandings were obtained on this challenging issue based on valuable comprehensive profiles from the Upper Cretaceous Songliao Basin, NE China (Qingshankou Formation, brief as K 2 qn1). 48 shale samples from the Central Depression in the northern Songliao Basin were analysed to establish three geochemical profiles of K 2 qn1. Multiple biomarkers suggested that organic matter in the source rocks of K 2 qn1 was mainly sourced from aquatic organisms. Systematic organic and inorganic geochemical analyses reveal that at least five transgressive events occurred during the sedimentary period of K 2 qn1, denoted as T I , T II , T III , T IV , and T V from bottom to top. In the context of multiple transgression events, the quality of K 2 qn1 source rocks was primarily controlled by lacustrine primary productivity. Importantly, transgression events have both positive and negative effects on the quality of lacustrine source rocks. During earlier transgressive events (e.g., T I and T II), the quality of source rocks was negatively correlated with transgression intensity, which is likely due to the difficulty of freshwater organisms adapting to salinity, resulting in a decline in primary productivity. In the later transgression events (e.g., T III and T v), the quality of source rocks was positively correlated with transgression intensity, which is probably due to the gradual dominance of salt-tolerant or halophilic organisms during multiple stages of salinization. This study provides a comprehensive research approach for evaluating the influence of transgression events on lacustrine source rocks. • Organic and inorganic geochemical analyses were used in combination. • Five marine transgression events were confirmed in the K 2 qn1 Formation. • The quality of K 2 qn1 source rock was primarily controlled by primary productivity. • Transgression events have both positive and negative effects on the quality of source rock. [ABSTRACT FROM AUTHOR]

Intensive cultivation in greenhouses of China has degraded the soil through acidification, salinization, and has caused an increase in soil-borne pathogens accumulation that negatively impacts vegetable production. In this study, six treatments, i.e. CK, degraded soil collected from greenhouse was irrigated to maximum field capacity and covered with plastic film; Al-RSD-F, flooding soil incorporated with alfalfa; Al-RSD, soil was incorporated with alfalfa, irrigated to maximum field capacity and covered with plastic film; Al-RSD + T37, inoculating Trichoderma harzianium T37 into soil at the end of the Al-RSD; Et-RSD, soil was incorporated with ethanol, irrigated to maximum field capacity and covered with plastic film; AW, soil was incorporated with ammonia and covered with plastic film, were conducted to investigate their effects on the physicochemical properties of degraded soil and disinfestations of Rhizoctonia solani , to control the damping-off disease in the two consecutive plantings of cucumber seedlings after the treatments. Treatments with Al-RSD-F, Al-RSD, Al-RSD + T37 and Et-RSD increased the pH and reduced the electrical conductivity of the soils, reduced population of R. solani and damping off of cucumber seedlings. These treatments with exception of Et-RSD, increased the populations of bacteria and fungi and showed higher diversity of bacteria after the second season of cucumber seedlings. Treatment AW was toxic and did not allow the survival of the cucumber seedlings. The treatments Al-RSD + T37 and Et-RSD showed the higher control of damping off, probably because the antagonist was favored by the previous treatment and could efficiently colonize the cucumber seedlings roots, and the Et-RSD was favored by the highest accumulation of toxic acetic acid in the soil. Alfalfa-amended soil disinfestations with or without Trichoderma , as well as an ethanol soil disinfestation could be used to recover degraded greenhouse soils. [ABSTRACT FROM AUTHOR]

• The N threshold of the unimodal response of CH 4 uptake was ∼10 g N m−2 yr−1. • The critical N addition rate to +/- abundance of pmoA gene was ∼7.0 g N m−2 yr−1. • N -induced changes in the plant community affect pmoA gene abundance through rhizospheric effects. Methane (CH 4) uptake in dryland ecosystems is a pathway in mitigating atmospheric CH 4 concentrations. A number of studies have demonstrated that nitrogen availability is a key regulator of the CH 4 oxidation process. However, how plants mediate soil CH 4 oxidation in response to N addition, particularly in saline-alkaline grasslands in the vast regions of the northern China, has received little attention. We conducted a 3-yr (2017–2019) in-situ experiment with eight N addition levels to examine the effect of N on soil CH 4 oxidation, and to explore the linkages between the N -induced changes of plant community and the seasonal dynamics of CH 4 in a saline-alkaline grassland. We found that the saline-alkaline grassland was a weak CH 4 sink displaying nonlinear CH 4 uptake levels in response to N additions, possibly due to the nonlinear changes in the abundance of key functional genes (pmoA) that were responsible for CH 4 oxidation. The changes in plant productivity and diversity that were induced by N additions explained 21 % of the variations in CH 4 uptake. The N -induced increase in productivity indirectly enhanced CH 4 uptake at N addition rates of <10 g m−2 yr−1, while the decrease in biodiversity indirectly inhibited CH 4 uptake when N addition exceeded 10 g m−2 yr−1. The N -induced changes in the plant community can affect CH 4 uptake, mainly through the rhizospheric effects of plants. In conclusion, our findings underscore the importance of rhizosphere when assessing the CH 4 uptake in saline-alkaline grassland ecosystems. [ABSTRACT FROM AUTHOR]

Salinization threatens the viability of water resources and is common in many important inland freshwater lakes worldwide, especially in arid and semi-arid areas. Bosten Lake is a typical inland freshwater lake that has evolved into a subsaline lake and is located in the arid region of Northwest China. The water resources of Bosten Lake are important for supplying regional drinking water and agricultural irrigation and for economic development. In this study, changes in salinity with time and space were analyzed in Bosten Lake. Overall, the salinity increased from 0.39 g/L in 1958 to 1.87 g/L in 1987, reaching its highest value in 1987. After 1987, the salinity decreased to 1.17 g/L in 2003 and increased to 1.45 g/L in 2010. Increased salinity adversely affects aquatic lake systems, regional eco-environments and water resource use, and has become a serious environmental problem in Bosten Lake. Thus, the causes of increasing salinity are discussed in this paper. Overall, the influences of climate variations and human activities resulted in the salinization of the lake. Understanding the salinization processes in Bosten Lake can be useful for implementing actions that improve water quality and water resource use in the lake. [ABSTRACT FROM AUTHOR]

The Yellow River Delta is a typical eco-environmental fragile region where soil quality is not high and salinization is universal, and it is of great significance for the rehabilitation and reconstruction of degraded soil to know the situation of degradation soil quickly and accurately in the region. This research chose Kenli County in the Yellow River Delta as the research area and the measured data in 2008 as the basis, and the comprehensive evaluation of soil degradation was carried out based on soil degradation composite index, which was built by weighted combination of soil degradation evaluation index weight and membership value. Using TM image that was at the same time as the measured data, the spectral characteristics of different soil degradation levels were researched, and the correlations between soil degradation composite index and the bands' gray values were analyzed; with the combination of qualitative and quantitative methods, the sensitive bands were screened. Then the sensitive spectral indices of soil degradation were built, based on which the remote sensing inversion model of soil degradation was established, and the exponential model was selected ultimately which had the highest fitting precision. Verified on the accuracy and the inversion results, the model was applied to the remote sensing images in 2011 and 2013, and the soil degradation dynamics were analyzed during 2008-2013 at last. The results showed the lower-degree degradation soil in the study area was far away from the ocean, and degradation degree of soil in close distance from ocean was relatively high; taken altogether, the extent of soil degradation from the coast to the inland in the study area showed a trend from high to low. The sensitive bands were TM1, TM2 and TM3, and the spectral indices of soil degradation based on the combination of these 3 sensitive bands were characteristic spectral indices of soil degradation. The regression function models were built by soil degradation spectral indices and soil degradation composite index, and the exponential model was the best, which had the highest F value and the best fitting. The remote sensing inversion model of exponential form based on the characteristic spectral indices of soil degradation had more higher accuracy, whose R² was 0.7182, and validation RMSE, relative error and determination coefficient were 0.0241, 3.66% and 0.6724, respectively. By contrast, the inversion results were consistent with the comprehensive evaluation results based on the measured data in the same year; in particular, the inversion results were more ideal in the area where the land types were relatively simple and the spectral information was relatively clear. The condition of soil degradation changed little in the study area during 2008-2013, and the specific performances were that the area of mild degradation soil increased and degradation soil at other grades decreased, a small amount of moderate degradation soil turned into mild, and there was a gradual improvement in the trend as a whole. This study provides technical support for monitoring the degradation soil in the Yellow River Delta, and provides decision-making basis for the sustainable utilization and protection of land resources in this area. [ABSTRACT FROM AUTHOR]

• A modified approach is used to evaluate the salinization time of a saline lake. • The salinization process is dominated by evaporation. • The transported and precipitated solutes are quantified over the salinization time. Under a warming climate, many areas of the world are experiencing drier conditions, leading to the rising lake evaporation rate and salinity. The salinization of a lake, or timescale needed to evolve from historically fresh to presently saline state, is important for understanding the paleo-hydrology and lacustrine geochemical cycling. Solute loss from transport (diffusion, advection, or density flow) and mineral precipitation in lake water are usually neglected in previous studies. Here, the salinization time of a saline lake in the Badain Jaran Desert, China is estimated based on the modified mass balance models of radium, barium, and chloride of lake water by considering the transport and precipitation loss of saline lake solutes. The calculated salinization time is 8,493.7 ± 1,559 years. The imbalance between imported solutes via groundwater discharge over the salinization time and their inventories in the present lake water suggests significant solute sinks through transport and precipitation. Specifically, sinks of barium, lithium, and strontium, have removed ∼ 10–100 times of the present-day inventories dissolved in lake water. These findings can guide the investigation of salinization processes in other saline lakes of similar hydrological and hydrogeological settings. [ABSTRACT FROM AUTHOR]

[Display omitted] • Illustrating the impacts of LULC changes on the landscape spatiotemporal patterns. • Evaluated the ecological security of the Ebinur Lake Wetland Reserve. • Ebinur Lake levels have been shrinking, and salinization is increasing annually. • Proposed ecological protection policies for the government. There is an increasing contradiction between humanity's growing demand for natural resources and relatively limited supplements. Thus, ecological security has received widespread attention, making it a research hotspot in the global environment and an important topic in construction of ecological civilization. Ebinur Lake Wetland is a typical arid wetland area considered as a fragile and sensitive ecosystem. Quantitative monitoring of the ecological security and landscape patterns of the Ebinur Lake wetland ecosystem is of great significance for environmental protection. To clarify the relationship between ecological landscape indices and land use/cover, this study used Landsat TM/OLI data from 1990, 1998, 2011 and 2021, aimed to analyze the correlated spatio-temporal changes of Ebinur Lake Wetland Reserve, China over past 32 years, in addition to quantitatively evaluating changes in ecological security. The results showed that (1) During 1990–1998, forest and paddy areas increased, while the transformation between paddy fields and wetlands was frequent, and from 1998 to 2011, land use/land cover (LULC) changes gradually stabilized, vegetation recovery was halted, and the water area obviously decreased. Since 2012, Ebinur Lake area decreased by −3.88 % per year, while 44.8 km2 of the subsoils became extremely severe salinized. (2) The variability of ecological landscape in spatial structure and time dynamics is enhanced, landscape scalability declined, resulting in the intensification of fragmentation. CONTAG (Contagion index) decreased annually with the decline in Gobi area; whereas landscape diversity of wetlands increased with growing light and heavy saline-alkali areas. (3) Overall ecological security gradually increased from 0.56 to 0.65, and the unsafe areas first decreased, before increasing slightly. The total saline-alkaline land area continued to increase, indicating that desertification cannot be curbed. Ecological security had the highest sensitivity to landscape separation, and the value range and its safety levels of ecological security (ES) were accurately delimited based on uncertainty calculation and frequency statistics. The results can provide reasonable and practical suggestions for the government and local communities on how to strengthen the ecological environment construction of Ebinur Lake Wetland Reserve. The government should several water-saving measures, in addition to an inter-basin water transfer project can be implemented to help diminish the consequences of insufficient water resources, and planting salt-absorbing vegetation to slow the salinization process. [ABSTRACT FROM AUTHOR]

Soil salinization is one of the most severe environmental problems restricting biodiversity maintenance and ecosystem functioning in a coastal wetland. Recent studies have well documented how salinization affects soil microbial communities along vegetation succession of coastal wetlands. However, the salinity effect is rarely assessed in the context of plant intraspecific variation. Here, we analyzed the soil bacterial and fungal communities of Phragmites australis wetland using amplicon high-throughput sequencing at a fine scale (within 1000 m) in the Yellow River Delta. Our results revealed that microbial diversity is significantly correlated to soil salinity (assessed as electrical conductivity, EC) but not to soil nutrients (N and P content) or plant intraspecific traits (leaf length, shoot height, and neutral genetic variation). Specifically, the microbial diversity tended to decrease with increased EC, and the bacterial community was more sensitive to EC change than the fungal community. The dominant bacterial phyla were Proteobacteria, Actinobacteria, and Chloroflexi, and the dominant fungal phyla were Ascomycota, Basidiomycota, and Mortierellomycota. The relative abundance of Actinobacteria was significantly negatively correlated to EC, while Proteobacteria were positively correlated to EC. In high salinity (> 1 mS/cm), the role of the stochastic processes became more important in community assembly according to habitat niche breadth estimation, neutral community model, C-score metric, and normalized stochasticity ratio. Additional common garden and microcosm experiments provided evidence that the genotype effect of P. australis on soil microbiome might only occur between lineages from different regions but not from the same region like the Yellow River Delta. Our findings provide new insights into soil microbial community assembly processes with the intraspecific variation of host plants in the wetland ecosystem and offer a scientific reference for salinity mitigation and vegetation management of coastal wetlands under future global changes., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

A field experiment was carried out in southern Xinjiang, China, to reveal soil-water flow pattern beneath a combined plastic-mulch (film) and drip-irrigation system using brackish water. The soil-water flow system (SWFS) was characterized from soil surface to the water table based on observed spatio-temporal distribution of total soil-water potential, water content and electric conductivity. Root suction provided a strong inner sink. The results indicated that SWFS determined the soil salinity and moisture distribution. Drip-irrigation events could leach excess salts from the root zone and provide soil conditions with a tolerable salinity level that supports the growth of cotton. High-salinity strips were formed along the wetting front and at the bare soil surface. Hydrogeology conditions, irrigation regime, climate, plant growth and use of mulch would affect potential sources and sinks, boundary conditions and the size of the SWFS. At depth 0-60 cm, the soil salinity at the end of the irrigation season was 1.9 times that at the beginning. Beneath the mulch cover, the soil-water content in the 'wide rows' zone (55 cm between the two rows with no drip line) was higher than that in the 'narrow rows' zone (15 cm between the two rows with a drip line) due to the strong root-water uptake. The downward water flow below the divergent curved surface of zero flux before irrigation, and the water-table fluctuation with irrigation events, indicated that excessive irrigation occurred. [ABSTRACT FROM AUTHOR]

Geochemical and isotopic characterization of groundwater and lake-water samples were combined with water and total dissolved solids balances to evaluate sources of groundwater quality deterioration in eastern Hetao Basin, Inner Mongolia, China. Groundwater quality is poor; 11 of 13 wells exceed drinking-water guidelines for at least one health-based parameter and all wells exceed aesthetic guidelines. The well water is largely derived from Yellow River irrigation water. Notably high uranium concentrations in the Yellow River, relative to world rivers, suggest groundwater uranium and other trace elements may originate in the river-derived irrigation water. Complex hydrostratigraphy and spatial variation in groundwater recharge result in spatially complex groundwater flow and geochemistry. Evapotranspiration of irrigation water causes chloride concentration increases of up to two orders of magnitude in the basin, notably in shallow groundwater around Wuliangsuhai Lake. In addition to evapotranspiration, groundwater quality is affected by mineral precipitation and dissolution, silicate weathering, and redox processes. The lake-water and TDS balances suggest that a small amount of discharge to groundwater (but associated with very high solute concentrations) contributes to groundwater salinization in this region. Increasing salinity in the groundwater and Wuliangsuhai Lake will continue to deteriorate water quality unless irrigation management practices improve. [ABSTRACT FROM AUTHOR]

Abstract: Mulched drip irrigation (MDI) has now become popular in arid and semi-arid areas, under which, however, salts are likely to build up in the surface soil due to deficient leaching water. To explore this new kind of secondary salinization issue, a 3-year experiment was conducted in an arid area in Xinjiang, northwestern China from 2008 to 2011. Over 15,000 soil samples were collected during the experimental years. The patterns of soil salinity distribution under MDI along the horizontal direction as well as vertical direction have been explored. Our results indicate that soil particle size distribution has great impact on soil salt migration and distribution. The salt will build up above the relatively impermeable layer along the soil profile. The zone below drip pipe obtains the lowest salinity level and the salt accumulates in the inter-film zone at the end of growth period. The salinity in the inter-film zone is 1.24–2.34 times the value in the zone below drip pipe within 50 cm soil depth, according to the soil texture. Furthermore, our analysis suggests that surface salinity distribution is dominated by MDI while the influence of MDI on salinity distribution is decreasing with the downward distance from ground surface. [Copyright &y& Elsevier]

Desertification and salinization are both threats to the ecosystem services in inland river oases of arid regions. Previous studies focus on either desertification or salinization, and there is a lack of joint studies on the two issues. The essential cause of desertification in a transition zone is usually concentrated irrigation water use, which leads to shrink of the subsurface flow field of groundwater, decline of the groundwater level, and loss of groundwater supply to the vegetation. The salinization problem in an oasis area is mainly caused by the local excess groundwater in the oasis, referring to secondary salinization, which leads to salt migration with the groundwater level rise to form salt crystallization at the land surface. Thus, the processes of desertification and secondary salinization are connected, and the solutions to the two problems can be complementary, i.e., by transporting the excess groundwater in the local secondary salinization area to the transition zone area where water is scarce. This paper, taking Luocheng Irrigation District in the Heihe River Basin of northwestern China as an example, estimates 1.76–4.70 million m3 of excess groundwater that can be extracted in the salinized area. Using this amount of water through engineering regulation, it is estimated that the transition zone nearby the irrigation district, which is under desertification threat, can be restored with an area of 23–212 km2. An engineering system is designed for coordinated groundwater regulation and the implementation with an experimental farm in the irrigation district is demonstrated. • Providing a new method to mitigate salinization and desertification in arid areas through groundwater regulation. • Estimating the amount of drainage from salinized oasis area in an irrigation district and the transition zone area to be recovered from desert. • Designing an engineering system for coordinated groundwater regulation. [ABSTRACT FROM AUTHOR]

Temporal changes in the quantity and chemical status of groundwater resources must be accurately quantified to aid sustainable management of aquifers. Monitoring data show that the groundwater level in Shahrood alluvial aquifer, northeastern Iran, continuously declined from 1993 to 2009, falling 11.4 m in 16 years. This constitutes a loss of 216 million m from the aquifer's stored groundwater reserve. Overexploitation and reduction in rainfall intensified the declining trend. In contrast, the reduced abstraction rate, the result of reduced borehole productivity (related to the reduction in saturated-zone thickness over time), slowed down the declining trend. Groundwater salinity varied substantially showing a minor rising trend. For the same 16-year period, increases were recorded in the order of 24% for electrical conductivity, 12.4% for major ions, and 9.9% for pH. This research shows that the groundwater-level declining trend was not interrupted by fluctuation in rainfall and it does not necessarily lead to water-quality deterioration. Water-level drop is greater near the aquifer's recharging boundary, while greater rates of salinity rise occur around the end of groundwater flow lines. Also, fresher groundwater experiences a greater rate of salinity increase. These findings are of significance for predicting the groundwater level and salinity of exhausted aquifers. [ABSTRACT FROM AUTHOR]

The Yellow River delta in China is one of the most active regions of land-ocean interaction. It has suffered serious salinization due to drying-up of the Yellow River, rising sea level, and seashore erosion, and thus represents a special and extreme environment. We evaluated the microeukaryotic molecular diversity and its response to change of seasons and environmental variables, in particular salinity in the soil of the Yellow River delta, by denaturing gradient gel electrophoresis (DGGE) and gene sequencing. The sequencing of the microeukaryotic DGGE bands revealed the presence of diverse groups dominated by protists in particular ciliates. We further recovered a high diversity of marine and soil ciliates inhabiting in coastal soil using the ciliate-specific DGGE. The neighbor-joining tree indicated that the ciliate 18S r DNA sequences from high-salinity soil were affiliated to Colpodea, Spirotrichea, Litostomatea, and Oligohymenophorea, while all the sequences unique to the low-salinity soil were affiliated to Colpodea. Statistical analysis indicated that the microeukaryotic molecular diversity was significantly different among sites, while statistically indistinguishable among seasons. Soil salinity might be the main factor regulating the distribution of microeukaryotes in the soil from the Yellow River delta. [ABSTRACT FROM AUTHOR]

Analyses of major elements, environmental isotope ratios (δ18O, δ2H), and PHREEQC inverse modeling investigations were conducted to understand the processes controlling the salinization of groundwater within the Datong Basin. The hydrochemical results showed that groundwater with high total dissolved solid (TDS) concentrations was dominated by sodium bicarbonate (Na-HCO3), sodium chlorite (Na-Cl), and sodium sulfate (Na-SO4) type waters, whereas low-TDS groundwater from near mountain areas was dominated by calcium bicarbonate (Ca-HCO3) and magnesium bicarbonate (Mg-HCO3) type waters. The characterization of the major components of groundwater and PHREEQC inverse modeling indicated that the aluminosilicate hydrolysis, cation exchange, and dissolution of evaporites (halite, mirabilite, and gypsum) governed the salinization of groundwater within the Datong Basin. The environmental isotope (δ18O, δ2H) and Cl−/Br− ratios revealed the impact of fast vertical recharge by irrigation returns and salt-flushing water on the groundwater salinization. According to the analyses of major hydrochemical components and PHREEQC inverse modeling, evaporite dissolution associated with irrigation and salt-flushing practice was probably the dominant controlling factor for the groundwater salinization, especially in the central part of the basin. Therefore, groundwater pumping for irrigation and salt-flushing should be controlled to protect groundwater quality in this area. [ABSTRACT FROM AUTHOR]

Aims Road effects from maintenance and traffic have the potential to alter plant communities, but the exact relationships between these effects and changes in plant community composition have not often been studied in diverse environments. To determine the direction and level of community composition changes in saline environment due to road effects, we conducted a study along roads of different ages and in nearby non-road (i.e. natural) areas in the Yellow River Delta, China. Additionally, to potentially elucidate the mechanisms underlying the changes in the richness and composition of plant communities along roads, we evaluated physiochemical changes in soil of roadside and non-road areas. Methods Floristic and environmental data were collected along roadside of different ages and nearby non-road areas. To evaluate plant communities at each site, six 2 m × 2 m quadrats were placed at 3-m intervals along roads and six quadrats were arranged randomly in non-road areas. To determine the difference in plant community composition between roadside and non-road areas, we measured species richness and the abundance of each species, examined species turnover and floristic dissimilarity between the two areas and positioned plant species and sites in an abstract multivariate space. Plant community (species richness, percentage of halophytes) and soil physicochemical properties (pH, salinity, moisture content, bulk density, nitrate and ammonium nitrogen concentration) were compared between roadside and non-road areas (young roadside vs. corresponding non-road areas, old roadside vs. corresponding non-road areas) by using t-tests. Classification and ordination techniques were used to examine the relationship between vegetation and related environmental variables in both roadside and non-road areas. Important Findings For both the young and old roadside areas, species richness in roadside areas was significantly higher than in non-road areas and high floristic dissimilarity values indicated that roadside and non-road areas differed greatly in community composition. In both the young and old roadside areas, the plant communities in roadside areas had lower percentages of halophytes than non-road communities. Correspondence analysis and two-way indicator species analysis showed that halophytes dominated in the non-road areas, while a number of typical non-salt-tolerant species dominated in the roadside areas. Compared to non-road areas, activities associated with roads significantly decreased soil moisture, bulk density and salinity and increased soil pH and nitrate content. Forward selection for the environmental variables in canonical correspondence analysis showed that soil salinity was the most important factor related to the variation of species composition between roadside and non-road areas. Our study demonstrates that road effects have a significant impact on the associated vegetation and soil, and these changes are consistent across roads of different ages in our system. [ABSTRACT FROM PUBLISHER]