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The salinity of the salt lake is an important factor to evaluate whether it contains some mineral resources or not, the fault buried in the salt lake could control the abundance of the salinity. Therefore, it is of great geological importance to identify the fault buried in the salt lake. Taking the Gasikule Salt Lake in China for example, the paper established a new method to identify the fault buried in the salt lake based on the multi‐source remote sensing data including Landsat TM, SPOT‐5 and ASTER data. It includes the acquisition and selection of the multi‐source remote sensing data, data preprocessing, lake waterfront extraction, spectrum extraction of brine with different salinity, salinity index construction, salinity separation, analysis of the abnormal salinity and identification of the fault buried in salt lake, temperature inversion of brine and the fault verification. As a result, the study identified an important fault buried in the east of the Gasikule Salt Lake that controls the highest salinity abnormal. Because the level of the salinity is positively correlated to the mineral abundance, the result provides the important reference to identify the water body rich in mineral resources in the salt lake. [ABSTRACT FROM AUTHOR]

In this paper, Yuqiao Reservoir is taken as the research object. The total suspended matter (TSM) produced by the economic development in the upper reaches of the reservoir and its surrounding areas has brought great ecological harm to the safe operation of the reservoir. Satellite remote sensing technology provides a good way to obtain the temporal and spatial variation of TSM in the study area. Two field surveys were carried out in the Yuqiao Reservoir, a total of 44 sampling points collected in the two tests. The spectral data and concentration of TSM were obtained. We developed and validated a robust empirical model to estimate the concentration of TSM in the water of the Yuqiao Reservoir for the first time. The TSM distribution map of the Yuqiao Reservoir in 2013–2018 is retrieved based on Landsat 8 OLI images. This paper analyzes the spatial distribution characteristics of TSM concentration in the Yuqiao Reservoir for several years, as well as the interannual, seasonal, and monthly variation laws and development trends. The results show that the spatial distribution of TSM in Yuqiao Reservoir shows a decreasing trend from the periphery to the center; the interannual changes are mainly as follows: The annual change trend of TSM in Yuqiao Reservoir is not obvious; the seasonal changes are significant: the highest in summer (higher than 40 mg/L), the second in autumn, and the lowest in spring and winter (lower than 15 mg/L); and the monthly changes show regular fluctuations: In a year cycle, the concentration of TSM generally shows an inverted V‐shaped trend; that is, TSM increases gradually from January to August and decreases gradually from August to December. The research results of this paper can be applied to other similar types of land water bodies, which will promote the wide application of Landsat 8 OLI images in the monitoring of TSM in lakes, rivers, and reservoirs in different regions across China, and provide data support for the scientific management of the safe operation of research areas. Practitioner points: The monitoring model of TSM in Yuqiao Reservoir was built for the first time.Temporal and spatial analysis of TSM concentration in Yuqiao Reservoir for the first time.The concentration of TSM is in Yuqiao Reservoir greatly affected by wind speed and precipitation. [ABSTRACT FROM AUTHOR]

Microbes play an important role in aquatic carbon cycling but we have a limited understanding of their functional responses to changes in temperature across large geographic areas. Here, we explored how microbial communities utilized different carbon substrates and the underlying ecological mechanisms along a space‐for‐time substitution temperature gradient of future climate change. The gradient included 47 lakes from five major lake regions in China spanning a difference of nearly 15°C in mean annual temperatures (MAT). Our results indicated that lakes from warmer regions generally had lower values of variables related to carbon concentrations and greater carbon utilization than those from colder regions. The greater utilization of carbon substrates under higher temperatures could be attributed to changes in bacterial community composition, with a greater abundance of Cyanobacteria and Actinobacteriota and less Proteobacteria in warmer lake regions. We also found that the core species in microbial networks changed with increasing temperature, from Hydrogenophaga and Rhodobacteraceae, which inhibited the utilization of amino acids and carbohydrates, to the CL500‐29‐marine‐group, which promoted the utilization of all almost carbon substrates. Overall, our findings suggest that temperature can mediate aquatic carbon utilization by changing the interactions between bacteria and individual carbon substrates, and the discovery of core species that affect carbon utilization provides insight into potential carbon sequestration within inland water bodies under future climate warming. [ABSTRACT FROM AUTHOR]

In the modern era, urban freshwater bodies play a significant role in global carbon (C) budgeting, therefore, impacting climate change under rising global mean temperature. However, the trend, magnitude and drivers of greenhouse gas (GHG) emissions in these urban freshwater bodies of China remain uncertain. This study investigated temporal changes in GHG emissions in urban water bodies, including artificial lakes, reservoirs, aquaculture ponds and rivers, within a year in Nanjing city in the areas of the Yangtze River delta of China. In addition, meteorological and hydrochemical parameters were measured to elucidate the key drivers of GHG emissions. The results showed that the average annual flux of carbon dioxide (CO2) and methane (CH4) in aquaculture ponds was estimated to be 1355.6 mg CO2 m−2 day−1 and 116.6 mg CH4 m−2 day−1, followed by that of artificial lakes were 1172.2 mg CO2 m−2 day−1 and 44.1 mg CH4 m−2 day−1, rivers reached 775.9 mg CO2 m−2 day−1 and 23.9 mg CH4 m−2 day−1 and reservoirs were 170.1 mg CO2 m−2 day−1 and 7.2 mg CH4 m−2 day−1, respectively. The results further suggest that although artificial lakes and aquaculture ponds occupied only 23% of the cumulative area under lakes and ponds in the Yangtze River delta, contribute approximately 43%, about 27.5 Gg C, of total fluxes. Furthermore, high concentrations of dissolved organic carbon (DOC) and low dissolved oxygen (DO) coincided with the high GHG emissions. The study suggests that DO, DOC, temperature and wind speed are the key factors impacting the potential of GHG emissions in urban freshwater ecosystems. Strategic mitigation measures in the vicinity of the urban freshwater bodies could efficiently reduce carbon emissions in the future. [ABSTRACT FROM AUTHOR]

Evaluating the spatial‐temporal dynamics in ecological risk and understanding its impact on water quality in reservoirs could optimize watershed land use and protect reservoir water quality. However, this impact remains elusive due to the lack of long‐term field data, the heterogeneity of land use, and scale effects. Therefore, Danjiangkou Reservoir area was selected as the study area, where rapid urban expansion and ecological conservation and restoration measures have significantly changed the ecological environment, altering the water quality. We investigated the spatial‐temporal changes of land use from 1990 to 2020 and evaluated how landscape ecological risk changed, as well as explored the impact of landscape ecological risk changes on water quality. The landscape ecological risk was calculated by landscape vulnerability and landscape disturbance (based on fragmentation, separation, and fractal dimension). The results indicated that the growth rate of water bodies surged (7.65 km2/a) and cropland experienced an apparent reduction (14.39%) over the past 30 years. These landscape changes decreased ecological risk, especially after the water transfer. The results revealed that the impacts of ecological risk on water quality were better explained at the riparian scale than at the reach and catchment scales. Specifically, the ecological risk was strongly relevant to dissolved oxygen, Turbidity, Cl− and NO3− ${{\text{NO}}_{3}}^{-}$, and moderately correlated to Ca2+ and pH. While it was not correlated with total nitrogen, total phosphorus, and F−, possibly due to the irregular reservoir operations, occasional excessive use of fertilizers, and rock weathering. This study preliminarily discloses the impact of landscape ecological risk on water quality in a basin reservoir and provides a theoretical basis to take measures in advance for the sustainable development of a reservoir basin. Plain Language Summary: Assessing the spatial and temporal dynamics of ecological conditions (denoted by ecological risk) and understanding their impact on reservoir water quality is not only important for optimizing land use in the basin, but also for protecting reservoir water quality. However, this impact remains elusive due to the limitations of existing studies and data. Therefore, the Danjiangkou Reservoir area was selected as the study area, where rapid urban expansion and major ecological conservation and restoration measures around the reservoir have significantly altered the ecological environment and water quality. We evaluated the changes in landscape ecological risk based on an investigation of spatial and temporal changes in land use between 1990 and 2020, and explored the impact of changes in landscape ecological risk on water quality. The results show that the rate of growth of water bodies has increased dramatically and the area of cropland has decreased significantly following the implementation of the dam raising project and water transfer. These landscape changes reduced ecological risk, improved ecological conditions and ultimately improved water quality. This study provides preliminary insights into the effects of landscape ecological risk on water quality and provides a theoretical basis for sustainable development of reservoir basins. Key Points: The ecological conditions and water quality in the rainy season were generally better than in the dry season during the same yearThe effect of the water transfer project on local ecological quality and water quality has been positiveThe improvement in eco‐environment quality reduced pollution sources and improved water self‐purification capacity, improved water quality [ABSTRACT FROM AUTHOR]

To identify the developmental characteristics and controlling factors of the beach‐bar sandstone in saline lake basins in the Qaidam Basin, China, the lithology and bedding structure of some representative outcrops of the Neogene saline lake basins were comprehensively investigated by means of experimental test data of local drilling cores, casting thin sections, and grain size, together with field outcrops in the basin and the modern salt lake deposition record of Qinghai Lake. Two types of sand bodies in the saline lake basins, that is, delta sand bodies and shore‐shallow lake beach‐bar facies were revealed. Neogene saline lake basins were found to host widespread beach‐bar sand bodies. Lithologically, the sand bodies were composed of fine‐grained sandstone and siltstone, with wavy bedding, low‐angle cross‐bedding, and bimodal cross‐bedding. The beach‐bar sandstone was characterized by multi‐layer superimposition, lateral migration, and NW–SE wide‐coverage continuation. Drilling data showed that beach‐bar sand bodies extended from 10 to 35 km in width and most of them occurred 3–15 km away from braided river delta front. It has been predicted that the total area of beach‐bar sand bodies of 14 sand groups in the Neogene spread across 5,000 km2. Four factors, that is, lake water salinity, terrigenous input, palaeogeomorphology, and monsoons, controlled the construction of the beach‐bar sand bodies developed in the Neogene saline lake of the Qaidam Basin. We can conclude that the settling velocity and transport distance of the sand bodies were affected by the water body salinity in such saline lake basins. Also, the distribution range of the beach‐bar sand bodies was affected by the clastic input from a terrigenous provenance. Furthermore, the wide‐coverage distribution and local enrichment of the beach‐bar sandstone were affected by palaeogeomorphology, and the distribution direction of the beach‐bar sandstone was affected by the driving effect of NW monsoons. We propose a deposition model of the beach‐bar sandstone in saline lake basins that can predict favourable beach‐bar sand body regions, to support the major discoveries of lithologic traps in southwestern Qaidam, China. [ABSTRACT FROM AUTHOR]

Shoal‐water deltaic systems are predominant during the deposition of the second member of the Eocene Shahejie Formation (Es2) in the Dongying Depression, Bohai Bay Basin, China, and their presence is ascribed to low slopes, shallow water bodies and extremely slow tectonic subsidence. Integrated analyses of sedimentological, seismic geomorphological, palaeohydraulic, palynological and element‐geochemical data reveal the influence of palaeoclimate on the morphology and depositional processes of distributary networks in shoal‐water deltaic strata. Two contrasting palaeoclimatic stages were identified based on palynological and geochemical evidence, namely the earlier warm and humid climatic stage, and the later arid climatic stage. Compared with the earlier humid stage, the arid stage features much more abundant xerophytic species (Labiatae and Ephedra) as well as much higher Mg/Ca, Sr/Ba, and Th/U ratios and B content, indicating extensive evaporation. A third‐order sequence stratigraphic unit was recognized, consisting of a transgressive systems tract with landward stepping parasequence sets, a poorly developed highstand systems tract, and a falling stage systems tract with basinward stepping parasequence sets, which were products of the humid and arid climatic stages, respectively. A series of distributary channel complexes exhibiting reticular patterns was identified in the strata corresponding to the humid climatic stage, with amalgamated, multi‐storey distributary channel sandbodies showing a sinuosity range of 1.1 to 1.3. In contrast, the strata corresponding to the arid climatic stage are dominantly composed of distributary channel systems exhibiting dendritic forms, with prevalent single‐storey channel fills and a low sinuosity range of 1.0 to 1.2. The dendritic system is more stable than the reticular counterpart due to the effects of frequent incision and limited vertical aggradation. Typical modern shoal‐water deltas formed in different climatic conditions (i.e. Poyang Lake delta and Neales River delta) serve as analogues to the proposed conceptual depositional models of distributary networks related to palaeoclimate. [ABSTRACT FROM AUTHOR]

Sustainable stormwater management (SSM) has gained global interests to solve both on‐site and off‐site downstream water problems. However, current structural SSM practices are often limited to small scales and their impacts on river water quality have not been fully understood. In this study, we have quantified watershed responses to SSM via multiyear monitoring and integrated modeling in an urbanizing watershed in China, while five scenarios (baseline, current SSM, improved SSM, future traditional urban development, and future improved SSM scenarios) were comparatively analyzed. The results showed that water quality of ammonia nitrogen (NH3‐N), total phosphorus (TP), chemical oxygen demand (COD), and suspended solid (SS) would deteriorate by both traditional urban development and current SSM design. Compared to other pollutants, NH3‐N and TP showed greatest deterioration by current SSM due to disproportionate management of on‐site runoff quantity‐related and quality‐related problems. Comparatively, the improved SSM design, which incorporated watershed responses into consideration, would reduce current concentrations of NH3‐N, TP, COD, and SS by 0–53.85%, 8.16–38.84%, 23.07–61.03%, and 68.82–77.82%, respectively; and improve water quality by 60–80% in future SMM scenario. Priority management and stricter objectives should be given to those urbanizing regions at the watershed scale. The results of this study should be used as references for future SSM design as well as water resource protection. Plain Language Summary: Sustainable stormwater management (SSM) is vital for urban water resources and water quality protection. However, watersheds serve as the end of the SSM system, the related water quality benefits from SSM have not been fully quantified. To address this problem, five scenarios were evaluated via multiyear monitoring and integrated modeling in an urbanizing watershed. Water bodies in the urbanizing areas are more vulnerable, which would multiply several times in pollutant concentrations by traditional urbanization. However, unexpected deterioration of river quality occurred by current SSM, although local runoff and pollutant loads were controlled. The improved SSM was then given by incorporating watershed response into SSM design to handle water problems at different scales. The findings and approach could undoubtedly facilitate the SSM development and watershed management, and could be applied in other cities and countries because urban expansion has become a global issue. Key Points: Unexpected river quality deterioration was found in current sustainable stormwater management (SSM) due to the neglect of relative reduction proportions in runoff and pollutant loadsVulnerable water bodies were found in urbanizing period, during which NH3‐N and TP were more sensitive to urbanization and SSMImproved SSM design was put forward by considering watershed responses through an integrated model [ABSTRACT FROM AUTHOR]

Flushing time is an integrative parameter that can represent water exchange capacity and sensitivity to pollution threats. As bays formed where tributaries enter the Three Gorges Reservoir of China have experienced frequent algal blooms over the past decade, we examine the spatially variable flushing time of a typical tributary bay (Xiangxi Bay) by numerical tracer experiments. First, the tracer concentration reduction could be approximated well by a double exponential decay curve, and the local flushing time of Xiangxi Bay is determined using key flushing coefficients. Second, a sensitivity analysis is performed to examine the influence of upstream inflow, temperature difference, wind, water level of the reservoir, and daily water level fluctuation on the spatial variation in local flushing time. Finally, according to local flushing time values and the sensitivity analysis results, the bay can be generally characterized by three zones: riverine, transitional, and mainstream‐influenced zones. In particular, the local flushing times in the riverine zone are mainly affected by the upstream inflow. The difference in temperature between the reservoir mainstream and Xiangxi Bay is the main forcing in the transitional and mainstream‐influenced zones. This study is the first to investigate different driving factors for flushing time in a typical reservoir tributary bay. The findings provide insights on the transport processes in such water bodies, suggesting the possibility of using the longitudinal zonation of flushing time for reservoir management. [ABSTRACT FROM AUTHOR]