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Abstract: Wetland, located in the terrestrial-aquatic transverse zone, is an important landscape and ecosystem. This paper describe the features and functions of wetlands, and take the case of lower reaches of the Yellow River wetlands, analysis on existing problems of ecological safety on wetland in lower reaches of the Yellow River. Using of GIS and two-dimensional water-sediment mathematical model of the Lower Yellow River, in accordance with the requirement of wetland areas, submerged areas for floods of below the 8000m3 /s magnitude designated as different functional areas. The ideal patterns of ecological security on the wetlands are divided into the core zone, buffer zone and experiment zone. [Copyright &y& Elsevier]

Abstract: This paper makes a research on “dragon scale felsenmeer” in Wansheng District in Chongqing by analyzing geological structure of limestone area in which “Crackle” has formed in South China through referring large amounts of data, and combing with the analysis of Ordovician sedimentary environment and diagenetic conditions. Based on the analysis, this study has made an initial judgment that “dragon scale felsenmeer” is controlled by sedimentary pattern in regional structure dynamic and sedimentary environment, and the pressure in diagenetic conditions. [Copyright &y& Elsevier]

Abstract: Following construction of the Three Gorges Dam, many farmers resettled in surrounding mountain areas and cultivated marginal lands, which are mostly on steep slopes with soil of poor structure. In general, high soil loss rates occur during intense storms. Therefore, soil erosion is a major environmental problem in the Three Gorges area (TGA) of China. Understanding and quantifying sediment load is important for sustainable agriculture and the environment in this region. This paper analyzes the relationships between rainfall, runoff, and sediment transport in the Wangjiaqiao watershed. Strong seasonal and monthly variability in sediment load was found. Sediment was strongly transported during summer months, a period when frequent flood events of high magnitude and intensity occurred. Analysis of the relationships between precipitation, discharge and sediment transport at an individual event scale showed significant correlations between total precipitation, peak discharge, total water yield, maximum 30min rainfall intensity, and sediment-related variables. Stepwise multiple regression analysis revealed that rainfall amount is the major cause of runoff, while events producing a large discharge in a short time play an important role in inducing severe soil erosion. During 40 flood events, three different types of hysteretic loops were observed: clockwise (28 events, 70%), figure-eight (5 events, 12.5%), and complex (7 events, 17.5%). The results of this study confirm the complex and heterogeneous nature of sediment response in the Wangjiaqiao watershed. [Copyright &y& Elsevier]

The article reveals that large regions of land subsidence present complicated deformation characteristics. It mentions that land subsidence caused by excessive groundwater withdrawal has occurred in parts of the world. A modified Merchant model is proposed to develop a visco-elastic-plastic constitutive relationship applicable in a regional land subsidence model. The deformation characteristics of sedimentary layers in Shanghai, China, are offered as case study.

Summary: Water shortage and water pollution are two major water issues in Northern China. In recent decades, the decrease in inflow and the deterioration of water quality in the Miyun Reservoir have affected the water supply in Beijing. This paper presents a geomorphology-based non-point source pollution (GBNP) model that links the processes of rainfall–runoff, soil erosion, sediment routing, and pollutant transport. On the basis of long-term simulation of the GBNP model, annual runoff presented a decreasing trend from 1980 to 2005. Total nitrogen (TN) and total phosphorus (TP) loads increased from the early 1980s to the mid-1990s, and then decreased after 1999. The decrease in precipitation and increase in air temperature were the dominant factors in runoff decrease. Afforestation, a water–soil conservation practice, positively affected the reduction of non-point source pollution; however, it also caused a reduction of streamflow. A comparison between 1980–1998 and 1999–2005 showed that land-use changes accounted for 39.1% and 23.7% of the decrease in TN and TP, respectively, as well as 6.6% and 9.2% of the decline in streamflow and sediment load, respectively. Although annual sediment, as well as TN and TP loads decreased after 1999, their long-term accumulation in the reservoir continues to diminish water quality. [Copyright &y& Elsevier]

Abstract: The chemical compositions of organic macromolecules in dust are very complex and have not yet been investigated in detail. In this paper, we study the organic macromolecules in 12 dust samples collected from an urban and suburban area of Guangzhou, China. Organic macromolecules in the dust were firstly separated into humic acids (HA), kerogen and black carbon (KB) and black carbon (BC) fractions by chemical treatment with NaOH, HCl/HF and K2Cr2O7/H2SO4, respectively. The isolated fractions were subsequently characterized using elementary analysis (EA), organic petrographic examination (OPE), scanning electron microscopy (SEM), and solid state 13C cross-polarization and magic angle spinning nuclear magnetic resonance spectroscopy (13C-CP/MAS NMR) etc. The results showed that the major organic macromolecules were KB, which accounted for 64.8%–95.8% of total organic carbon (TOC) in the dusts. Isolated HAs were characterized by high H/C, N/C and O/C atomic ratios, and high carboxyl, methoxyl and aliphatic carbon contents in the overall carbon structure; meanwhile, kerogens (K) showed lower H/C, N/C and O/C atomic ratios than those of HAs and had chemical compositions enriched in hydroxyl carbon; further, the optical features of K were similar to those of “vitrinite”. BC is formed from the combustion of biomass and fossil fuels, so that aromatic and aliphatic carbons are the most important components in its carbon skeleton. Under the microscope, BC appeared to belong to the petrographic groups, such as “semifusinte” and “fusinite”, and showed a distinct texture when observed by SEM. Compared with the HAs and K isolated from soils and sediments, HAs in dust were relatively lower in aromatic carbon and K in dust was always “type III”. These results are strongly consistent with the dust samples originating from the photochemical degradation of volatile organic compounds, in contrast to the geological HAs and K which are sourced from the biodegradation of lignin and algae or from bacterial activities in water and sediment. [Copyright &y& Elsevier]

Abstract: This paper focuses on the physical properties and spatial distributions of the Permian sandstone reservoirs in Bohai Bay Basin and the adjacent areas in the northeast China. The coal-formed gas sandstone reservoirs occur in the Permian Shihezi Formation and the maturity of the sandstone in the lower part is gradually higher than that in the upper part. The high-maturity sandstones are mainly the channel lag deposits and widely distributed in the study area. Due to the low porosity and permeability, however, the sandstones formed only the medium-poor reservoirs. The sandstones contain clay matrix and commonly a small portion of calcareous, siliceous, and authigenic clay cement. On the other hand, severe compaction and cementation caused nearly complete destruction of the primary porosity during diagenesis. Therefore, the main space of the sandstone reservoirs comes from the secondary pores. The distributions of reservoirs are affected by several periods of faulting and denudation. The sandstones of the Lower Shihezi Formation are thicker in the Jizhong and Bozhong depressions, and Luxi areas, and those of the Upper Shihezi Formation are thicker in Jizhong and Jiyang depressions and thinner in Luxi areas. [Copyright &y& Elsevier]

Abstract: This paper examines the spatial variation of sediment yield in the Yangtze basin in China, a large basin with complex geology, climate, land-use history, and extensive sediment monitoring. 287 stations with drainage area less than 10,000km2 were used to study the scale effects of sediment yield. In order to develop scale relations for regional sediment yield, the whole study area was divided into eight sub-basins. Relation between specific sediment yield and drainage basin area was built for each sub-basin. Regional scaling relation was analyzed based on landforms, geology, lithology and land-use of each sub-basin. Three regional trends were identified in relation to the drainage area: (1) a declining trend, due to soil erosion on heavily cultivated steep land and the storage of sediment in floodplains; (2) a flat trend, due to mass movement on the upper reach and heavy agricultural disturbance on the middle and lower reaches; and (3) an increasing trend, due to downstream recruitment of sediment from land downstream where slope farming and deforestation occurred. Using these developed relations, areally adjusted sediment yield maps were created over the entire Yangtze basin. [Copyright &y& Elsevier]

Abstract: Natural gas hydrates (NGH) can only exist under low temperature (generally below 10 °C) and high pressure (generally above 3.8 MPa). The prerequisite for investigations of NGH sediments is a sampling technique that prevents its volatiles during recovery. In this paper, some pressure and temperature preservation techniques for NGH sampling are investigated and analyzed intensively. The Chinese pressure and temperature corers including tight rock core sampler, pressure tight piston corer, wireline coring sampler and hydraulic pressure and temperature preservation (HPTP) corer are introduced in detail. Two pressure chambers (pressure chamber I and pressure chamber II) are designed with passive temperature preservation technique; using pressure accumulator (PA) cylinder pressure preservation technique, the pressure chamber was applied on the South China Sea at the water depth of 1352 m in 2006. Laboratory tests and the sea application show that the pressure preservation technique of the PA cylinder and the passive temperature preservation technique are successful for NGH sediments sampling. The main focus of future developments for NGH samplers in China is given, which offers the reference to the optimal design for the structure of NGH samplers and the new sampler development. [Copyright &y& Elsevier]

A new hydraulic, water-lifting aerator was developed for ameliorating water quality. It aims at mixing lower and upper water bodies, controlling algae growth, increasing dissolved oxygen concentration in water and inhibiting the release of pollutants from sediments. This new device was applied to control the algae growth in surface water of the water source of Tianjin. It was found that the content of agrology chlorophyll-a was reduced by 13.96%, and the growth of algae was inhibited. In this paper, the theory and application conditions of this new device for controlling algae are discussed. [ABSTRACT FROM AUTHOR]

Abstract: Heavy metal contamination of bottom sediments of the Changjiang River is widely reported, however, the potential source and methods of transportation of these heavy metals in the contaminated sediments is poorly defined. This paper examines the correlation between heavy metals and geochemical indices, including Fe2O3, Al2O3, total organic carbon (TOC) and black carbon (BC), as well as magnetic susceptibility (MS). Using these indices we investigate the contamination characteristics of heavy metals in the sediments by with Principal Component Analysis (PCA). Results from 83 sediment samples collected in the lower reach of Changjiang River (from Nanjing to Shanghai) show that the first principal component accounts for 52.23% of the total variance, corresponding to the heavy metals, Co, Cr, Cu, Ni and Zn, and conservative components of Fe2O3, Al2O3 and TOC. This result indicates that heavy metal distributions are controlled by the transportation and sedimentation of fine particles which is also confirmed by particle size analysis. The second principal component explains 24.81% of the variance and is dominated by Cd, Pb and MS, which, collectively, result chiefly from industrial and transportation activities and, for MS, fly ash production. The third principal component accounts for 7.91% of the variance and corresponds solely to Hg. Principal component analysis/multiple linear regression (PCA/MLR) was used to estimate the contribution of the three principal components to each heavy metal. PCA/MLR results suggest that more than 50% of Co, Cr, Cu, Ni and Zn were influenced by the particle size effect. Particle size effect and fly ash account for 37.1% and 27.7% of As. Cd and Pb were mainly explained by fly ash. 98.9% of Hg was related to PC3, which represented black carbon (BC). Our study indicates that the combination of geochemical and multivariable statistical methods clearly characterizes the geochemistry of heavy metals in sediment of the lower reaches of the Changjiang River and suggests that power plants are the main source of heavy metal pollution. [Copyright &y& Elsevier]

Abstract: The Piqiang Fault is a prominent strike-slip (tear) fault that laterally partitions the Keping Shan Thrust Belt in the NW Tarim Basin, China. In satellite images, the Piqiang Fault appears as a sharp, NW-trending lineament that can be traced for more than 70km. It is oblique to the general structural trend of the thrust belt and subparallel to the thrust transport direction. This paper presents a structural analysis of the Piqiang Fault, based on satellite image interpretation and field data. A net loss of Late Paleozoic sediment across the fault zone implies that it was initiated as a major normal fault during the Early Permian, and corresponds to widespread extension and magmatism during this period. Differential erosion across the fault resulted in the subsequent removal of sediment from the east relative to the west. During the Middle to Late Cenozoic, contraction of the NW Tarim Basin and the formation of the Keping Shan Thrust Belt resulted in reactivation of the Piqiang Fault as a strike-slip (tear) fault. The fault has accommodated lateral differences in thrust density and spacing which have arisen due to the abrupt, pre-existing change in stratigraphic thickness across it. The Piqiang Fault provides an insight into the formation of oblique, strike-slip (tear) faults in contractional belts and demonstrates the importance of inherited basement structures in such settings. [ABSTRACT FROM AUTHOR]

Abstract: Matrix bound phosphine (MBP) is commonly considered an important phosphorus form in the natural environment. This paper presents an investigation of the spatial distribution of MBP and its relationship with the environmental factors in the Changjiang Estuary and its adjacent shelf areas (29.5–32°N, 122–124°E). A total of 32 surface sediment samples were collected from April 24 to 30, 2008. MBP was detected in all samples from the Changjiang Estuary and its adjacent shelf surface sediments (0.1–29.7 ng kg−1). The concentration of MBP decreased from the Changjiang Estuary to the East China Sea shelf. Environmental factors such as organic matter, type of sediments, and redox conditions were found to affect the concentration and distribution of MBP in the marine sediments. Although the MBP levels were low in the marine sediments, the marine biogeochemical cycles of MBP in sediments were established and the information presented here will contribute to the understanding of the biogeochemical cycle of phosphorus. [ABSTRACT FROM AUTHOR]

Sediment concentrations of Chinese rivers are among the highest worldwide. If the sediment concentration exceeds a certain value, the flow dramatically changes exhibiting properties different from low-concentration sediment-laden flows, both in the movement and the pattern of sediment transportation. The hyperconcentrated flow exhibits distinct phenomena, such as 'instability flow', 'clogging river', or 'blast flow'. Such flow phenomena are related to the formation, development and break-up of a hyperconcentrated laminar layer, and also reflect the transition from laminar to turbulent and return to laminar flow. The turbulence intensity of the hyperconcentrated flow is normally weak with turbulence largely damped as the sediment concentration becomes sufficiently high. It was found that the instability of hyperconcentrated flows is not only controlled by the critical Reynolds number, but also related to sediment concentration, distribution of the sediment in water, and the size and density of the sediment particles. [ABSTRACT FROM AUTHOR]

An article by Zhang et al. questions the interpretation of our oxygen isotope record from Wanxiang Cave and the sediment titanium record from Lake Huguang Maar, and the possible linkage between climate change and Chinese culture. In response, we explain that their approach lacks logical rigor and their major argument is broadly consistent with, rather than contradictory to our original conclusions. We also note that climate-culture relationships similar to those that we observe in China have been observed for other cultures around the world. [ABSTRACT FROM AUTHOR]

Abstract: Long-term changes to the Yellow River delta in China have received considerable attention not only because of the growing economic importance of the delta region but also because they provide a clear example of the dominant role played by anthropogenic effects upon a large dynamic river delta. This paper presents a detailed study on the morphological consequences of reduction in river sediment load and influence of human activities based on sediment load data at three gauging stations in the upper, middle and lower reaches of the Yellow River basin from 1950 to 2007. The results indicate that sediment loads at all three gauging stations display a gradually decreasing trend over the past 58years. The primary reason for this decrease is shown to be due to various human activities, including the construction of Longyangxia and Liujiaxia reservoirs in the upper reaches, water–soil conservation practices and the commissioning of Sanmenxia and Xiaolangdi reservoirs in the middle reaches. It is estimated that water–soil conservation practices which are a major factor to the decrease of sediment load at Huayuankou gauging station account for 40% of the total amount of reduction, sediment trapping by Sanmenxia and Xiaolangdi reservoirs account for 30% of the total amount of reduction and the 10% decrease is caused by human activities in the upper reaches. The remaining 20% decrease is attributed to precipitation decrease. The reduction of sediment load has directly impacted on the lower Yellow River and the delta region, causing alternate changes between siltation and scouring in the lower river channel along with an increased rate of erosion over the whole Yellow River delta. [Copyright &y& Elsevier]

Abstract: Details are given in present paper of the development of a sediment transport and morphological model to predict the bed evolution processes in tidal flows. The model is based on an existing hydrodynamic and sediment transport model (DIVASTSED), but with significant refinements being made. A single size sediment transport module is refined to include capability for simulating the transport of graded sediments under non-equilibrium conditions. Both cohesive sediment and non-cohesive sediment are taken into consideration in present study. The fall velocity of suspended sediment is modified in present model due to the high sediment concentration. A 3-layer approach is adopted to simulate the variations of sediment gradations of bed materials. The model is used to simulate the bed evolution in the Yellow River Delta from 1992 to 1995, the numerical results show how the morphology developed in the Yellow River Delta and agree well with the field data. The present model could provide an effective tool for the management of wetland in the Yellow River Delta. [ABSTRACT FROM AUTHOR]

Abstract: Floods often are accompanied by intensified soil erosion and thus high sediment supply from the catchment into the main channel of the river. This paper examined the sediment processes, especially deposition and erosion, during the two extreme flood years in 1954 and 1998, in the middle and low reaches of the Yangtze River. The total amount of sediment supplied to the middle and lower reaches from Yichang–Hankou and Hankou–Datong, was 1095 Mt in 1954 and 855.9 Mt in 1998, or 176% and 137% of the averaged 622 Mt/a from 1950 to 2006. A high deposition occurred in the floodplains, lakes and channels along the section Yichang–Hankou, both in 1954 and 1998. The total deposition reached 635 Mt and 499 Mt in 1954 and 1998 or 138% and 124% of the sediment load measured at the Datong station, respectively. However, different processes in the downstream section Hankou–Datong during the two flood events were found. Severe erosion (−140 Mt) happened in 1954, but only a slight erosion occurred (−22 Mt) in 1998. Thus, the floodplains and channels in the middle and lower reaches of the Yangtze River play an important role in regulating sediment discharge during extreme flood events. The heavy deposition in the middle reaches effectively reduced the amount of sediment discharged into the river mouth and thus acted as a major depocenter in the extreme flood year. The results also suggested that the Yichang–Hankou tended to shift from a depositional section to an erosional section, whereas the Hankou–Datong changed from an erosion-dominated section to a deposition-dominated section even before the Three Gorges Reservoir infilling in 2003. It is anticipated that this tendency would be accelerated and the historical role of sediment regulation by the two reaches could eventually be changed due to the reduced sediment supply from the Upper Yangtze. [ABSTRACT FROM AUTHOR]

Abstract: This paper characterizes the distribution of phosphorus fractions and matrix-bound phosphine (MBP) in coastal surface sediments of the Southwest Yellow Sea from 2006 to 2007. Total phosphorus (TP), inorganic phosphorus (IP) and organic phosphorus (OP) concentrations (mgkg−1) range from 278±3 to 768±15, 160±1 to 653±27, and 3.42±0.05 to 267±22, respectively. MBP is a small portion of TP with values of 0.69±0.06 to 179±29ngkg−1. Phosphorus fractions and MBP are influenced strongly by riverine input and hydrodynamic conditions. High TP and MBP are found in the old Yellow River mouth and the Yangtze River mouth. OP and MBP are strongly negatively correlated to mean particle size. Significant positive correlations are found between MBP and IP and OM, suggesting that MBP production may be the microbially intermediated transformation of IP. [Copyright &y& Elsevier]

Abstract: Radiocarbon can serve as a powerful tool for identifying sources of organic carbon and evaluating the erosion intensity in river drainage basins. In this paper we present 14C-AMS measurements of particulate organic carbon (POC) collected from the three major tributaries of the Zhujiang (Pearl River) system: the Xijiang (Western River), Beijiang (Northern River) and Dongjiang (Eastern River) rivers. Furthermore, we discuss the distribution of POC 14C apparent ages and the related watersheds erosion of these rivers. Results yield Δ14C values of −425‰ to −65‰ which indicate that the 14C apparent ages of suspended POC in the entire area are in the range of 540–4445years. The POC apparent ages from Xijiang are mostly between 2000 and 4000years, while in Dongjiang they mostly range from 540 to 1010years. These 14C apparent ages indicate that the watershed erosion of the Xijiang is more severe than that of the Dongjiang. This is in agreement with other data showing deeper erosion in Xijiang due to human activities. [Copyright &y& Elsevier]

Abstract: The well-developed, late Cenozoic Nihewan Beds in northern China are amongst the most famous and well-preserved Quaternary strata in East Asia. The Nihewan Basin is also well-known for its mammalian fossils and stone artifacts, which document early human settlements in high northern latitudes (around 40°N). It is a key geological place to study palaeoenvironments and ancient human activities due to the excellent age-control of the formation by palaeomagnetism. In the present paper, the sediments of two Paleolithic sites were dated using the ESR signals of the titanium center in quartz. In order to check the reliability of our analytical procedures, a reference sample collected near the Brunhes/Matuyama (B/M) boundary at the Donggutuo site was firstly analyzed, yielding an age of 750 ± 88 ka. Then, three samples collected from the Dongpo site were analyzed by the same procedures. Our ESR results indicate that the age of the Dongpo cultural layer ranges between 304 ± 12 ka and 333 ± 23 ka, with an average of approximately 321 ± 15 ka. [Copyright &y& Elsevier]

Abstract: Traditional measurements of suspended sediment concentrations (SSC) through in-situ sampling in rivers are expensive and time-consuming to perform. Thus, these methods cannot provide continuous SSC records. Although remote sensing has been used for SSC estimation, little research has been undertaken on inland rivers, especially for highly turbid rivers like the Yangtze. Previous studies have proposed Landsat TM/ETM+ Band 4 as a spectral SSC indicator for the Yangtze, but its limitation on temporal resolution is insufficient for the study of dynamic changes of sediment. This paper presents a method of estimating SSC of the Yangtze at Jiujiang using time-series satellite data of high temporal resolution Terra MODIS. It was found that differences in water reflectance between Band 2 and Band 5 could provide relatively accurate SSC estimation even when in-situ atmospheric conditions were unknown. After cross-validation, mean absolute relative error (ARE) and relative root mean square error (RRMSE) were relatively low (i.e., 25.5% and 36.5%, respectively). This empirical relationship was successfully applied to the estimation of SSC at Datong in the Lower Yangtze River, although the SSC values were generally underestimated. This study suggests that Terra MODIS could be used to estimate SSC in large turbid rivers, although some influencing factors require further study to improve the accuracy of SSC estimation. [Copyright &y& Elsevier]

The Honggang member of the early Paleogene Buxin Formation is the main source rock in the Sanshui Basin, characterized by organic-rich black shales with the cyclic recurrence of organic-poor sediments. The geochemical characteristics of the Honggang member have been documented to determine the organic matter types and depositional environments in this paper. The organic matter of the black shales mainly consists of a mixture of land plant-derived and phytoplankton-derived organic matter. Total organic carbon content (TOC)-sulfur-iron (Fe) relationships suggest that the organic-rich black shales were deposited under dysoxic-to-euxinic water conditions. The time that iron minerals remained in contact with H2S in anoxic waters possibly influenced the formation of syngenetic pyrite, and organic carbon controlled the formation of diagenetic pyrite. Organic-poor intervals usually show pyrite sulfur enrichment and higher degree of pyritization values relative to low organic carbon contents. This resulted from HS− diffusing downward from overlying organic-rich sediments and formed Fe sulfides through reactions with sufficient Fe. Trace elements generally exhibit low concentrations and little TOC dependence, suggesting some degree of depletion in these elements in the early Paleogene sediments of the Sanshui Basin. This probably resulted from cyclic recurrences of oxic benthic conditions, which promoted the remobilization of trace elements and caused the low concentration of trace elements. [ABSTRACT FROM AUTHOR]

Abstract: A laboratory study of the rheology of mudflows in Hangzhou Bay, China, is reported in this paper. Both the steady and oscillatory (dynamic) rheological properties are studied using RMS-605 rheometer. A Dual-Bingham model is proposed for analyzing flow curves and compared with Worrall-Tuliani model. It is found that Dual-Bingham plastic rheological model is easier to implement than Worrall-Tuliani model and can provide satisfactory representations of the steady mudflows in Hangzhou Bay and other published data. The dependence of the yield stress and viscosity on sediment concentration is discussed based on the data from Hangzhou Bay mud and other published data. For the dynamic rheological properties of Hangzhou Bay mud, empirical expressions for elastic modulus and dynamic viscosity are provided in the form of exponential functions of sediment volume concentration, and comparisons with other published data also discussed. [Copyright &y& Elsevier]

Abstract: The vertical distribution of polycyclic aromatic hydrocarbons (PAHs) at different sediment depths, namely 0–2cm, 2–4cm, 4–6cm, 6–10cm, 10–15cm and 15–20cm, in one of the most contaminated mangrove swamps, Ma Wan, Hong Kong was investigated. It was the first time to study the intrinsic potential of deep sediment to biodegrade PAHs under anaerobic conditions and the abundance of electron acceptors in sediment for anaerobic degradation. Results showed that the total PAHs concentrations (summation of 16 US EPA priority PAHs) increased with sediment depth. The lowest concentration (about 1300ng g−1 freeze-dried sediment) and the highest value (around 5000ng g−1 freeze-dried sediment) were found in the surface layer (0–2cm) and deeper layer (10–15cm), respectively. The percentage of high molecular weight (HMW) PAHs (4 to 6 rings) to total PAHs was more than 89% at all sediment depths. The ratio of phenanthrene to anthracene was less than 10 while fluoranthene to pyrene was around 1. Negative redox potentials (Eh) were recorded in all of the sediment samples, ranging from −170 to −200mv, with a sharp decrease at a depth of 6cm then declined slowly to 20cm. The results suggested that HMW PAHs originated from diesel-powered fishing vessels and were mainly accumulated in deep anaerobic sediments. Among the electron acceptors commonly used by anaerobic bacteria, sulfate was the most dominant, followed by iron(III), nitrate and manganese(IV) was the least. Their concentrations also decreased with sediment depth. The population size of total anaerobic heterotrophic bacteria increased with sediment depth, reaching the peak number in the middle layer (4–6cm). In contrast, the aerobic heterotrophic bacterial count decreased with sediment depth. It was the first time to apply a modified electron transport system (ETS) method to evaluate the bacterial activities in the fresh sediment under PAH stress. The vertical drop of the ETS activity suggested that the indigenous bacteria were still active in the anaerobic sediment layer contaminated with PAHs. The biodegradation experiment further proved that the sediment collected at a depth of 10–15cm harbored anaerobic PAH-degrading bacterial strains (two Sphingomonas, one Microbacterium, one Rhodococcus and two unknown species) with some intrinsic potential to degrade mixed PAHs consisting of fluorene, phenanthrene, fluoranthene and pyrene under low oxygen (2% O2) and non-oxygen (0% O2) conditions. This is the first paper to report the anaerobic PAH-degrading bacteria isolated from subsurface mangrove sediment. [Copyright &y& Elsevier]

Abstract: The adsorption of phosphorus (P) on four sediment samples (CunTan, XiaoJiang, DaNing and XiangXi) from the Three-Gorges Reservoir on the Yangtze River in China was studied systematically in batch experiments. A sequential chemical extraction experiment was conducted to clarify the effect of sediment composition on P adsorption. The results showed that P adsorption on four sediment samples mainly occurred within 6h. P adsorption kinetics can be satisfactorily fitted by both power function and simple Elovich model. A modified Langmuir model may describe well the P adsorption on all the samples in our study. Theoretically, the maximum adsorption amount (Q max) was 0.402mg-P/g for XiaoJiang sediment, 0.358mg-P/g for DaNing sediment, 0.165mg-P/g for CunTan sediment, and 0.15mg-P/g for XiangXi sediment. The sediment compositions such as organic matter, metal hydroxides, calcium and clay content showed influences on the P adsorption. Wherein, organic matter and metal hydroxides were the main factors affecting the P adsorption. The maximum P adsorption capacity (Q max) enhanced with the increase of the content of (Fe+Al+Ca). Compared the zero-equilibrium P concentration (EPC0) values obtained by the modified Langmuir models with actual P concentrations in water, all the sediments studied in this paper except for XiaoJiang showed a trend of releasing P as a source role, which could enhance the risk of eutrophication occurrence in the Three-Gorges Reservoir. [Copyright &y& Elsevier]

• The near-dam region contributed 10.8% of the total sediment into the reservoir. • Sedimentation mainly occurred in bending, branching and near-dam reaches. • The key factor influencing sedimentation was the incoming sediment load. • New formulas were proposed to calculate sediment trapping efficiency. Sedimentation in the Three Gorges Reservoir (TGR) affects flood control, navigation, power generation and the ecological environment. We present a comprehensive analysis of the characteristics of sedimentation in the TGR from 2003 to 2018. The data set includes field measurements (runoff and sediment) at hydrological stations and estimation for areas where measured data are not available. Based on the data set, the amount of sedimentation in the TGR was calculated with the Sediment Budget Model (SBM) and Section Topography Method (STM). Finally, the variation in sediment Trapping Efficiency (TE) in the TGR was assessed. The results indicate that sediment from smaller tributaries in the TGR region, which has been ignored in most previous studies, constituted approximately 10.8% of the total incoming sediment. The total sedimentation in the TGR was 205478 × 104 t in 2003–2018, and the contribution rates of sediment load flowing into the TGR, the water depth in front of the dam, and runoff discharge flowing into the TGR were 94.4%, 24.5% and −18.9% respectively. The average annual TE was 78.5% in 2003–2018, and it was closely related to the ratio of reservoir storage capacity to flow discharge in the flood season and to sediment concentration in the non-flood season. The results in this paper not only play an important role in the optimal operation of the TGR but also have important reference value for other large reservoirs worldwide. [ABSTRACT FROM AUTHOR]

In this paper, the distribution, degree of pollution and sources of Cu, Pb, Zn, Cd, Cr, As, Co, Ni and Hg in the surface sediment of Sanmen Bay were studied. The average concentrations of the identified potentially toxic elements (PTEs) were in the following order: Zn > Ni > Cr > Cu > Pb > Co > As>Cd > Hg. Almost all PTEs had a significant positive correlation with TOC, clay and Al; Cr had no significant correlations. Apart from Hg, the contamination levels of 8 PTEs were at those considered to be low-to-no pollution. Comparatively, the contamination level of Hg was much higher than the background value, which indicated moderate pollution. The source of this pollution may have included industrialization, urbanization and/or transport of industrial waste materials. Both geoaccumulation index (I geo) and potential ecological risk (RI) values suggested that Hg was the major contributor to the ecological risk posed by the selected PTEs. • The pollution of PTEs in Sanmen Bay of China was evaluated. • The concentration of PTEs in sediment descended Zn>Ni>Cr>Cu>Pb> Co>As>Cd>Hg. • Grain size and TOC were the factors controlling the distribution of most PTEs. • Hg was a non-negligible toxic element which posed a moderate ecological risk. [ABSTRACT FROM AUTHOR]

Abstract: Draining toward the South China Sea, the Pearl River is the third largest river in China. Based on datasets begun in the 1950s of water and sediment flux at the main gauging stations and measured deposition rates in some reservoirs, this paper examines the impact of dam construction on the sediment flux of the Pearl River. The results and conclusions are as follows: (1) The total storage capacity of reservoirs in the Pearl River basin had reached 65 km3 by 2005, which is 23% of the annual water discharge of the Pearl River. (2) The total deposition rate in the reservoirs has now probably reached 600 Mt/yr, one order of magnitude higher than the annual sediment flux into the sea (40 Mt/yr in 2000–2005). (3) The sediment flux of the Pearl River has shown a drastically decreasing trend since the mid-1980s, which is attributed mainly to deposition in the reservoirs. (4) A further decrease in sediment flux into the sea is expected to occur in the Pearl River in future decades because of the construction of new dams. This drastic decrease in sediment flux may be very import for the environments of the river channel, the estuary and the coastal areas, which need to paid considerable attention in scientific research and management. [Copyright &y& Elsevier]

In this paper, the changes in runoff and sediment yield have been assessed by using long-term observation data from 9 gauging stations on the Yellow River and 12 climate stations in the Yellow River watershed in China. It was observed that the annual precipitation depth at 3 climate stations in the headwater region of the Yellow River has an upward trend. However, in the lower section of the Upper Reach sub-watershed of the Yellow River, the annual precipitation depth has a slightly downward trend. In the Middle Reach sub-watershed, annual precipitation depth has a clear downward tendency. In the Lower Reach sub-watershed of the Yellow River, annual precipitation depth has a slightly upward tendency. Results indicate that, both annual sediment yield and annual runoff depth have a tendency of reduction in the past half century. The annual sediment yield in the Middle Reach is extremely high, with a long-term annual sediment yield of 1543.65 t/km² at the Longmen station and 1631.39 t/km² at the Tongguan station. In the Lower Reach, both annual runoff depth and sediment yield have a clearly downward trend. However, the long-term average annual sediment yield in the Lower Reach varies from 1035 to 1330 t/km2 which is still extremely high but less than those at gauging stations on the Middle Reach. The average annual sediment yield decreased significantly in recent 10 years. Examplewise, for the Yellow River at Lijin Station, the average runoff depth of the recent 10 years is only 1/3 of the long-term average value, and the average annual sediment yield of the recent 10 years is only 1/4 of the long-term average value. Additionally, the impacts of human activities on both runoff depth and sediment yield have been discussed. [ABSTRACT FROM AUTHOR]

Abstract: Formation of bound residues of pollutants in soils and sediments is an important process to control the fate of pollutants in the environment. The most of bound residue is not solvent extractable. In this paper, we measured both extractable and non-extractable polycyclic aromatic hydrocarbons (PAHs) in different organic matter fractions of samples from the Pearl River Delta, China. Non-extractable PAHs concentration was 234.45–1424.57μg/kg and accounted for 33.78–57.44% of total PAHs. 2–3 Ring PAHs were the dominant species and differed in concentration substantially between the samples. The atomic ratio of PAHs over organic-C in the fractions ordered as solvent soluble organic matter>humin>humic acids, matching the content of aliphatic moieties in the fractions of organic matter. The ratio of extractable and non-extractable PAHs may relate to the aging process of PAHs in soil and sediment. [Copyright &y& Elsevier]

Abstract: Expansion of irrigation in the Yellow River (Huang He in Chinese) Basin of China is a major accomplishment of the post-revolutionary period in China. Irrigation reliance on the Yellow River was anticipated to not only supply greater reliability of water for crops, but also to improve the productivity of aeolian, saline and alkali soils because of the high sediment loads in the river. Irrigation expansion also was a significant factor in affecting human modification of the landscape ecosystem in the lower reaches of the Yellow River. Based on field investigation and sampling of the amount and distribution of used suspended sediment load in irrigated areas, this paper analyzes the impact of the suspended sediment on soil texture, fertility and salinity and the consequences to the landscape ecosystem. Results indicate that soil quality has indeed been improved through irrigation and related deposition of sediment, but some local problems created by long periods of irrigation should not be ignored in the future. [Copyright &y& Elsevier]

Abstract: Siliciclastic, carbonaceous and phosphoritic shallow marine sediments from several Neoproterozoic (Ediacaran) and Precambrian–Cambrian (PC–C) boundary sections on the Yangtze Platform, South China contain remarkable trace fossil assemblages. The present paper provides a general overview on the distribution and the possible palaeobiological and palaeoenvironmental significance of these trace fossil assemblages from selected PC–C boundary sections on the passive Yangtze Platform margins. Comparative investigations of the typology of Neoproterozoic (Ediacaran) ichnofaunas as well as of the related sedimentary environments accompanying the ichnoassemblages demonstrate in general correspondence with other studies worldwide that the Neoproterozoic ichnofaunas are mainly composed of slightly curved to straight and unbranched horizontal traces, which are usually related to the occurrence of shallow marine softgrounds sealed by microbial mats. Rare traces show ichnomorphological patterns that indicate developments toward a more effective horizontal exploitation of the feeding ground during the late Neoproterozoic and earliest Cambrian. The majority of these traces appear to represent undermat miners with simple feeding strategies. During the earliest Phanerozoic (early Meishucunian Stage, equivalent to the Nemakit–Daldynian Stage of Siberia), the oxic shallow-water environments along the ancient continental passive margins of the Yangtze platform were populated by large, as yet unknown arthropods which produced Rusophycus-type trace fossils. The late Precambrian to early Phanerozoic sediments of the Yangtze Platform generally provide excellently preserved trace fossil records, which together with the presence of index fossils (SSF) from the Nemakit–Daldynian Stage, provide a more detailed insight into the development of PC–C palaeoenvironments and the evolution of lifestyles among early bilaterian metazoans. A preliminary comparison of the Neoproterozic biotas occurring on the Yangtze Platform and in other time-equivalent (Ediacaran) habitats demonstrates general similarities but also some striking differences, probably due to palaeoenvironmental variations. The data presented here from South China are critically discussed in the light of current palichnological approaches and theories. [Copyright &y& Elsevier]

The modern Yellow River Delta is formed by fine-grained sediments through fast transportation and accumulation. Its coast is characterized by partially consolidated bed structure, high water content and weak erosion resistance. Despite recent advances in numerical morphodynamic modeling techniques, the current ability to predict long-term coastal changes at the Yellow River Delta is hampered by the lack of reliable data on the erosion resistance of the sediments deep in the bed. This paper describes a laboratory-based erosion study using a 30 m sediment core collected from the tidal flat on the northern coast of the Yellow River Delta in April 2004. The influence of various sediment properties such as bed stratification, grain composition, wet bulk density and water content on the measured erosion resistance has been analyzed in detail. The results reveal that there exist a definite negative relationship between the critical erosion shear stress and water content or median diameter, and also a clear positive relationship between the critical erosion shear stress and clay content. For the sediments of the same type, there was a positive relationship between the critical erosion shear stress and wet bulk density. It was also found that the erosion resistance changes considerably through depth with the lowest being near the surface and the highest at a depth of 9.1–13.5 m. The relationship between erosion rate and shear stress for erosion was shown to be dependent in a complex way on the grain distribution, sedimentation structure, wet bulk density and water content of the sediments. A number of distinct erosion behavior have been identified and although in most cases the erosion rate (ε) can be related linearly to the net bed shear stress (τ-τc), further study is needed to establish the erosion-stress relationship for the case where the erosion seems to show undulating behavior. [ABSTRACT FROM AUTHOR]

Summary: Annual runoff and annual suspended sediment loads of hydrological gauging stations along the mainstream of the Yangtze River basin (Pingshan station, Yichang station, Hankou station and Datong station) and main tributaries (Beipei station in Jialingjiang River, Wulong station in Wujiang River and Huangzhuang station in Hanjiang River) were analyzed with the help of Mann–Kendall trend analysis and linear regression analysis. Research results indicate that (1) changing patterns of runoff and sediment loads are different in different parts of the Yangtze River basin. No significant trend is detected for annual runoff at all stations at >95% confidence level. Changes of sediment loads, however, demonstrate different pictures in the Yangtze River basin. The sediment loads are in increasing trend in Pingshan station- the most upstream station on the Yangtze River basin (this increasing trend is significant at >95% confidence level after about 1990), but are in decreasing trend at other stations (including stations in the tributaries studied in this paper). This decreasing trend becomes more obvious from Yichang station to Datong station. (2) Water reservoirs exerted more influences on changes of sediment loads than on runoff, which is the main reason for the decreasing trend of sediment loads found in most stations. (3) Influences of water reservoirs on sediment loads are more obvious in the tributaries than in the mainstream of the Yangtze River basin, while in the mainstream the variation patterns of sediment loads are determined by multiple factors. [Copyright &y& Elsevier]

Abstract: This paper addresses the recent (1970s–1990s) processes of river mouth bar formation, riverbed aggradation and distributary migration in the Huanghe River mouth area, in the light of station-based monitoring, field measurements and remote sensing interpretation. The results show that the morphological changes of the river mouth bar have been closely associated with the largely reduced fluvial discharge and sediment load. Landform development such as bar progradation occurred in two phases, i.e. before and after 1989, which correspond to faster and lower bar growth rates, respectively. Fast riverbed aggradation in the mouth channel was strongly related to river mouth bar progradation. During 1976–1996, about 2.8% of the total sediment loads were deposited in the river channel on the upper to middle delta. Therefore, the river water level rose by a few meters from 1984 to 1996. The frequent distributary channel migration, which switched the radial channel pattern into the SE-directed pattern in the mid-1980s, was linked with mouth bar formation. Marine conditions also constrain seaward bar progradation. Furthermore, the history of river mouth bar formation reflects human impacts, such as dredging and dyking in order to stabilize the coastal area. [Copyright &y& Elsevier]

Contents of rare earth elements (REEs), major elements, and the total organic carbon (TOC) were determined for 152 surface sediment samples collected from the continental shelf off Hainan Island (CSHI). From high to low, the average contents of REEs were as follows: Ce > La > Nd > Pr > Sm > Gd > Dy > Er > Yb > Eu > Ho > Tb > Tm > Tm. The LREEs in the south are more abundant than in the north, which is shown by the higher LREE/HREE values in south than in the north. This resulted higher values for the LREE/HREE ratio in the south than in the north. The mean enrichment factor (EF) could be arranged from highest to lowest as follows: Tm > Sm > Pr > Er > La > Lu > Ce > Tb > Eu > Nd > Yb > Gd > Ho > Dy. The EF indicates that pollution as a result of human activity was more serious in the southeast of the study area than in the north. The factors affecting the REE concentrations in this area include naturally occurring minerals and industrial pollution. Based on the spatial variation of upper continental crust (UCC)-normalized REE concentrations, the CSHI was classified into three geochemical provinces. The sediment of province I was controlled by the Red and Pearl rivers. The composition of the province II is mainly controlled by the Red River and the Pearl River, although some sediments have originated from the South China Sea Island. Province III sediments mainly originated from sources on Hainan Island. [ABSTRACT FROM AUTHOR]

Spatial variations in grain size parameters can reflect river sediment transport patterns and depositional dynamics. Therefore, 22 surficial sediment samples taken from the Heihe River and its cascade reservoirs were analyzed to better understand the impact of cascade reservoir construction on sediment transport patterns in inland rivers in China. The results showed that the longitudinal distribution of sediment grain size in the Heihe River was significantly affected by the influence of the cascade reservoirs. The retention rate in the cascade reservoir of the Heihe River reached 79% (193.53 Mt/year), which caused most of the fine sand to accumulate in the reservoir, and the sediment fining degree reached approximately 50%. However, the water discharged from the dam caused serious erosion of the riverbed and coarsening of the sediment, and the coarsening degree was approximately 500%. The backwater zone of the reservoir was influenced by both backwater and released water, and the coarsening degree of sediment was approximately 101%. Sedimentary environmental analysis revealed that the characteristics of the sediment grain size in an upstream tributary of the Heihe River were more influenced by source material than by hydrodynamic conditions, while the grain size characteristics of the mainstream sediments were controlled mainly by hydrodynamic conditions. The characteristics of sediment transport in different reaches of the Heihe River were studied, and the results may provide references for the operation of cascade reservoirs and the sediment control of reservoirs. [ABSTRACT FROM AUTHOR]

Marine bacteria in the seawater and seafloor are essential parts of Earth's biodiversity, as they are critical participants of the global energy flow and the material cycles. However, their spatial-temporal variations and potential interactions among varied biotopes in artificial habitat are poorly understood. In this study, we profiled the variations of bacterial communities among seasons and areas in the water and sediment of artificial reefs using 16S rRNA gene sequencing, and analyzed the potential interaction patterns among microorganisms. Distinct bacterial community structures in the two biotopes were exhibited. The Shannon diversity and the richness of phyla in the sediment were higher, while the differences among the four seasons were more evident in the water samples. The seasonal variations of bacterial communities in the water were more distinct, while significant variations among four areas were only observed in the sediment. Correlation analysis revealed that nitrite and mud content were the most important factors influencing the abundant OTUs in the water and sediment, respectively. Potential interactions and keystone species were identified based on the three co-occurrence networks. Results showed that the correlations among bacterial communities in the sediment were lower than in the water. Besides, the abundance of the top five abundant species and five keystone species had different changing patterns among four seasons and four areas. These results enriched our understanding of the microbial structures, dynamics, and interactions of microbial communities in artificial habitats, which could provide new insights into planning, constructing and managing these special habitats in the future. [ABSTRACT FROM AUTHOR]

On Earth, salt environments are the most relevant analogues to Martian salt deposits with regard to the search for preserved biomolecules. In this study, we analyzed the distribution of lipids in salt samples from Dalangtan and Qarhan in the Qaidam Basin, which is the most important area to carry out analog research of Mars in China. Furthermore, we compared the lipids distribution results with that from other typical Martian analog sites such as the Atacama Desert. Salt samples in the Qaidam Basin are enriched with fatty acid compounds, including normal fatty acids, unsaturated fatty acids, branched fatty acids, and acyclic isoprene acids. In addtion, glycerol dialkyl glycerol tetraethers (GDGTs) and archaeol compounds were also detected in these salt samples. Compared with the hypersaline samples, the clay samples not only have higher abuandance of fatty acids, GDGTs and archaeol compounds, but also a more diversed lipids composition. Only a few lipids were detected in the pure-saline samples, such as archaeol compounds. These clues suggest that content of salt minerals is the major factor affecting the distribution of lipids. This study provides an analogy for detecting and evaluating the traces of life that may exist on Mars. [ABSTRACT FROM AUTHOR]

In this work, a strain named YPW1 was isolated from the sediments of an artificial mangrove in Yanpu harbor, China. A complete genome of YPW1 was sequenced and assembled. The 16S rRNA gene assigned strain YPW1 into genus Microbulbifer, and the maximum values of average nucleotide identity and digital DNA–DNA hybridization of ZHDP1 genome were 90.36 and 68.1, respectively, indicating that YPW1 was a potential new species in genus Microbulbifer. A total of 10 representative genomes from genus Microbulbifer were selected to compare with YPW1. The results showed that the genome of strain YPW1 possessed more carbohydrate-active enzyme genes to transform various recalcitrant polysaccharides into bioavailable monosaccharides than those of the selected genomes. Furthermore, among the selected genomes, YPW1 was the only strain with nitrate, nitrite, and nitric oxide reductases which could appoint nitrous oxide, a powerful greenhouse gas, as the end-product of its denitrification process. Therefore, strain YPW1 was a potential novel member of genus Microbulbifer with special ecological roles in the cycles of carbon and nitrogen in mangrove ecosystems. [ABSTRACT FROM AUTHOR]

Rivers in the north-western region of China have a high sediment content, and the construction of reservoirs on these rivers must address the problem of sedimentation that results in a loss of reservoir capacity. In this study, the YZD (Yazidang) reservoir was considered as a typical case, to address the problem of sedimentation in injection-type water supply reservoirs in Northwest China. The temporal and spatial characteristics of the sediment in this water diversion project were analyzed based on available 46-year water and sediment data. The concept of 'sediment avoidance diversion' was proposed, which reduces the entry of sediment into the reservoir. A one-dimensional numerical model for water-sediment coupling was established, and the characteristics of water-sediment erosion and deposition for different operational modes were analyzed. The results show that during a period of high sediment content, large-scale siltation occurs in a water diversion channel. To alleviate sediment deposition in a diversion channel, two control strategies for mitigating siltation were formulated. Considering the pros and cons of these control strategies, a reasonable water-sediment joint operation plan has been proposed to extend the service life of the YZD reservoir. This research provides a theoretical basis for sedimentation treatment and control of similar reservoirs. [ABSTRACT FROM AUTHOR]

Core, well log and seismic data are used to investigate relationships between fan-delta facies architecture, basin margin morphology and sediment transportation into a deep-lacustrine environment of the Dongying Formation of Nanpu Sag, Bohai Bay Basin. The study interval is subdivided into two fan-delta dominant, third-order sequences of Stratasequence Paleogene Dongying Formation 1 (SQEd1) (younger) and Stratasequence Paleogene Dongying Formation 2 (SQEd2) (older). Fan-delta growth occurred in two stages with changing of facies architecture and morphology. During the early stage (SQEd2), the facies architecture is characterised by smaller and thin, channelised deposits, an extended mouth bar (delta-front sandy deposits) and slump/slides/flood turbidite dominated sandy deposits in the prodelta. However, during the late stage (SQEd1), the facies architecture is characterised by extended and thicker channelised deposit-dominated area, a local mouth bar (delta-front sandy deposits) and slump/slide-dominated sandy deposits in the prodelta. From the early to late stage, the delta morphology also changed with an upward increase in the delta-plain areal extent and delta-front gradient. Facies architecture variations indicate differences in sediment dispersal. The upward thickening and extending delta plain implies that more sediment was trapped in the proximal area owing to sufficient accommodation space generated by increasing boundary fault displacement. The upward increasing delta-front gradient resulted in differences in the type of prodelta/deep-lacustrine sandy deposits, while grainsize variations of the delta-front deposits affect the prodelta/deep-lacustrine sandy deposits. Boundary fault growth occurred with upward increasing displacement and length with the result that sediment supply outpaced accommodation-space creation and controlled the facies architecture changes. A two-stage fan delta developed with changing facies architecture is analysed. Facies architecture controlled fan-delta morphology with sediment transport into a deep-lacustrine area. Faults control the facies architecture and sand-rich deposit distribution. [ABSTRACT FROM AUTHOR]

Metal contamination from base metal sulphide mines is a major environmental challenge that poses many ecological and health risks. We examined the metal concentrations in the Dabaoshan mine in South China in water, sediments, and aquatic organisms and their specific characteristics (i.e. size, body tissue, species, and habitat) along the Hengshi and Wengjiang River courses to assess acid mine drainage remediation efforts. Metal concentrations of arsenic, cadmium, chromium, copper, lead, nickel, thallium, and zinc were examined in tissues (i.e. gills, intestines, and muscles) of 17 freshwater species of fish, shrimps, and crabs. Metals in tissues followed the trend: intestines > gills > muscles; nearly all intestine samples exceeded the safe limits of metals analysed in this study. There is a positive correlation between distance from the mine and metal concentrations related to the flow of surface water and the habitat of aquatic organisms. The concentrations of arsenic, copper, and zinc were the highest in aquatic organisms, and the distribution was influenced by physical (distance from mine, currents, and seasonality), chemical (pH and competing ions), and biological (species, habitat, and predator–prey relation) factors. Large demersal fish and benthic fauna had higher concentrations of metals. Bioaccumulation and biomagnification of metals, as well as the high metal pollution index and target hazard quotient (arsenic, cadmium, copper, lead, thallium, and zinc), occurred in bottom feeders (C. aumtus, X. argentea) and fish belonging to higher trophic levels (P. fulvidraco, O. mossambicus). Lead and cadmium indicated the highest level of biomagnification from prey to predator. Health risks exist from the dietary intake of common aquatic species such as tilapia and carp besides crustaceans due to high arsenic, cadmium, lead, and thallium levels. Further reduction of metals is necessary to improve the effects of acid mine drainage in the catchment. [ABSTRACT FROM AUTHOR]

This paper systematically describes the molecular and isotopic characteristics of Meso- to Neoproterozoic (1.73–0.85 Ga) sediments from the Jixian section, Yanshan Basin, North China. A correlation is made between molecular fingerprints and paleoenvironmental and paleontologic data acquired from these strata. The agreement between these parameters suggest that the biomarkers preserved in these Proterozoic sediments are good indicators of the evolution of the paleoenvironment and early life in the Yanshan Basin. The fact that extended regular isoprenoids (>C20) were detected in most of the studied samples suggest a sustained lipid input to sedimentary organic matter from halophiles and other possible archaebacteria through Meso- to Neoproterozoic. Two dehydroabietin isomers (i.e. 18- and 19-norabieta-8,11,13-trienes) were unexpectedly present in these samples, which provides evidence suggesting that the compounds with abieta structure could be derived from primitive organisms such as algae. The stable carbon isotope characteristics of kerogen and coexisting carbonate show a rapid decline in atmospheric CO2 concentration from 1.73 to1.58 Ga, and a stable concentration afterwards. The difference (ΔC) in isotopic composition between carbonate and associated kerogen lies in zonal variations along the stratigraphic sequence, which can be attributed to the alternations of marine transgressions and regressions that occurred in the Yanshan Basin during the Proterozoic. The carbon isotope relationships between kerogen and alkanes from these strata are consistent with the hypothesis that before 1.4 Ga both n-alkanes and isoprenoids had been derived mainly from heterotrophic halophiles and other archaebacteria, but after that only isoprenoids originated from archaebacteria whereas n-alkanes were possibly derived from photosynthetic organisms. Changes in the source of n-alkanes around 1.4 Ga may suggest a decline of heterotrophic reworking to primary lipids, which can be related to the formation of a quiet, shallow-water environment of an epicontinental sea at this stage in the Yanshan Basin. [Copyright &y& Elsevier]

Ten samples of slope-wash and colluvial deposits from a trench wall at Xiyangfang, Yanqing County, located in the northern margin fault zone of the Yanqing Basin, about 90 km northwest of Beijing, have been dated by both green light stimulated emission (GLSL) and infra-red stimulated emission (IRSL). Four of the samples were measured in both Adelaide (Risø equipment) and Beijing (Daybreak equipment), with essentially consistent results. The paper gives a comparison of equivalent dose values obtained by both GLSL and IRSL. The Xiyangfang trench wall presents four fault-scarp-collapsed wedges, showing a clear normal faulting pattern, which can be interpreted as a record of palaeo-earthquake events, covering a time period from about 100 ka to the modern. A return time of about 7000 yr is suggested for events at this site. An attempt is made to correlate the dating records with the local earthquake history of destructive earthquakes in the last 2000 yr. [Copyright &y& Elsevier]

A new 210Pb-dated record of Hg accumulation derived from a sediment core from a Hg-enriched area in Huguangyan Lake (HGY) in South China is presented. Based on synthetic analyses of multi-proxy records including chemical composition, total organic matter, and grain-size distribution in surface sediments and nearby soil samples, it is inferred that the influx of Hg into the lake is mainly a result of atmospheric deposition, with no or minor hydroclimate-induced lithogenic input from the catchment and limited adsorption effects of organic matter and clay. Significantly enhanced anthropogenic input of Hg started in the early 1900s. Since then, several anomalies of Hg accumulation have been the results of wars or intensified economic activities in China. HGY sediments provide a rare and reliable natural archive for detecting atmospheric Hg deposition, which is closely related to anthropogenic activities. [ABSTRACT FROM AUTHOR]

Runoff and sediment discharge have displayed great reductions due to climate change and enhanced various human activities during recent decades in the Jialing River, China, with significant environmental and social implications. The water balance equation, double mass curve, and linear regression analysis were employed to quantify the contributions of climate change and human activities to runoff and sediment discharge reductions in the Jialing River during 1960–2017. The results indicated that the annual runoff of the Jialing River exhibited a significant decreasing trend of − 2.75 × 108 m3 every year (P < 0.05) but no significant abrupt change occurred, while annual sediment discharge significantly decreased by 0.03 × 108 t every year (P < 0.05) with a significant abrupt change in 1990 (P < 0.05). Climate change led to a great reduction (82.2%) in annual runoff from 1960 to 2017 in the Jialing River, whereas the contribution of climate change to sediment discharge reduction in the human-affected period (1990–2017) was only 4.55% and precipitation inclined to increase sediment discharge in recent years (2010–2017). The reduced sediment discharge in the 1990s was mostly due to the implementation of soil–water conservation programs and the reduction after 2000 was due to the development of reservoirs as well as the implementation of soil–water conservation programs. The results provided references to develop various human activities better and drew great attention to strengthening basin management. [ABSTRACT FROM AUTHOR]

Landscape evolution is modulated by the regional tectonic uplift, climate change, and river dynamics. However, how to distinguish these mechanisms through the research of surface exhumation and fluvial incision remains controversial. In this study, cosmogenic 10Be, 26Al, and 21Ne concentrations in quartz from cave deposits, modern river sediments, and bedrocks were measured to constrain the applicability of cosmogenic 21Ne and discuss Quaternary landscape evolution history in the Guizhou Plateau, southeast China. Using the 26Al-10Be and 21Ne-10Be pairs to distinguish the cosmogenic 21Ne concentration from the excess 21Ne, we found that the nucleogenic 21Ne produced by the U and Th decay in quartz is significant in the samples although there is the possibility of inherited cosmogenic 21Ne. Combining with previous studies, we suggest that the precise approach for applying the cosmogenic 21Ne could be reached by (1) estimating the contribution from nucleogenic 21Ne, (2) avoiding samples with complex burial histories to exclude inherited cosmogenic 21Ne, and (3) combining the 10Be-26Al-21Ne nuclides method for the Quaternary samples. In addition, both pre-burial basin denudation rates and burial ages derived from the 26Al-10Be pair were used to determine the different timescale surface denudation rate and fluvial incision rate in relation to previous work. The consistency of the different timescales pre-burial basin denudation rate, 36Cl surface denudation rate, and modern basin denudation rate indicates that the landscape-scale surface denudation has been likely stabilized since the Quaternary in the Guizhou Plateau area. The slightly higher river incision rates than the local surface denudation rate show that the river dynamics may not have reached a steady-state due to the regional tectonic uplift in the Guizhou Plateau. [ABSTRACT FROM AUTHOR]

Investigation of the variations in runoff, sediment load, and their dynamic relation is conducive to understanding hydrological regime changes and supporting channel regulation and fluvial management. This study is undertaken in the Xihanshui catchment, which is known for its high sediment‐laden in the Jialing River of the Yangtze River basin, southern China, to evaluate the change characteristics of runoff, sediment load, and their relationship at multi‐temporal scales from 1966 to 2016. The results showed that runoff changed significantly for more months, whereas the significant changes in monthly sediment load occurred from April to September. The contributions of runoff in summer and autumn and sediment load in summer to their annual value changes were greater. Annual runoff and sediment load in the Xihanshui catchment both exhibited significant decreasing trends (p < 0.05) with a significant mutation in 1993 (p < 0.05). The average annual runoff in the change period (1994–2016) decreased by 49.58% and annual sediment load displayed a substantial decline with a reduction of 77.77% in comparison with the reference period (1966–1993) due to climate change and intensive human activity. The power functions were satisfactory to describe annual and extreme monthly runoff–sediment relationships, whereas the monthly runoff–sediment relationship and extreme monthly sediment‐runoff relationship were changeable. Spatially, annual runoff–sediment relationship alteration could be partly attributed to sediment load changes in the upstream area and runoff variations in the downstream region. Three quantitative methods revealed that the main driver for significant reductions of annual runoff and sediment load is the human activity dominated by soil and water conservation measures, while climate change only contributed 22.73%–38.99% (mean 32.07%) to the total runoff reduction and 3.39%–35.56% (mean 17.32%) to the total decrease in sediment load. [ABSTRACT FROM AUTHOR]