[Spatiotemporal Variations in Nutrient Loads in River-lake System of Changdang Lake Catchment in 2016-2017].

Eutrophication of shallow lakes in the middle and lower reaches of the Yangtze River has become an increasingly serious problem. In this study, we investigated the temporal and spatial variations in nutrient loads (nitrogen, N and phosphorus, P) in the Changdang Lake Catchment located to the northwest of Lake Taihu through field sampling and laboratory analysis in 2016-2017. The results show the severity of the N and P pollution in the Changdang Lake catchment.

[Thermal Stratification and Its Impacts on Water Quality in Shahe Reservoir, Liyang, China].

Based on the one-year hourly water temperature profiles and the associated environmental drivers during the past eight years in Shahe Reservoir, Jiangsu Province, China from 2009 to 2016, the factors underlying the seasonal variation of thermal stratification and water quality response were investigated. It was shown that the thermal stratification was a typical subtropical one-cycle mixing model, lasting from May to September. The thermal stratification appeared and disappeared when the surface water temperature was 21 ℃ in the late spring and 19 ℃ in the middle of autumn.

[Impact on nitrogen and phosphorous export of wetlands in Tianmu Lake watershed].

Focused on understanding the function of wetland in improving water quality, Pingqiao watershed and Zhongtian watershed in Tianmu Lake drinking water sources area were selected as the research region. We integrated remote sensing, GIS techniques with field investigation and chemical analysis to analyze the relationship between wetland and water quality in watershed scale. Results show: (1) There are many wetland patches in Pingqiao and Zhongtian watershed, wetlands patch densities were respectively 7.

[Impacts on nutrient export by landscape heterogeneity based on sub-watershed].

Landscape features of a watershed are important factors affecting non-point source (NPS) pollution. Sub-watershed bounds were delineated and landscape heterogeneity was analyzed based on GIS and RS in Xitiaoxi watershed which located the upper reach of Taihu Lake area. Nutrient export intensity of sub-watersheds was estimated by revised export coefficient model.

[Spatio-temporal changes of nitrogen balance in 1980-2005 for agricultural land in Three Gorges Reservoir Area].

Based on the long-term agricultural statistics data at the county scale, the estimation of nitrogen balance from 1980 to 2005 for agricultural land in Three Gorges Reservoir Area was made by the OECD soil surface nitrogen balance model with some suitable modification. The spatio-temporal changes of nitrogen balance and its drivers were analyzed. The results showed that the total inputs and total surplus of nitrogen from 1980 to 2005 presented increasing trends continuously, from 23.

[Estimated nutrient export loads based on improved export coefficient model in Xitiaoxi watershed].

It is very important to estimate nutrient export loads from watershed, which is beneficial to water environmental management. The export coefficients for major land use types were evaluated by field surveying data, in addition the spatial distributions of precipitation and runoff were considered, to improve on export coefficient model (ECM), then integrated ECM into geographical information system to compose half-distribution model of export coefficients. Estimated nutrients export loads based on the ECM in Xitiaoxi watershed located upper of Taihu Lake area.

[Influence of landscape characteristics on non-point source pollutant output in Taihu upper-river basin].

Based on the observed data in monitored drainage areas and GIS spatial analysis tools, watershed basic database of Taihu upper-river basin was built. Using the methods of multiple stepwise regression and redundancy analysis, the influence of landscape characteristics on non-point source pollutant output at the outlets of watersheds and their relative influence intensity were analyzed. The dominant landscape characteristics influencing non-point source pollutant output in Taihu upper-river basin and sub-watersheds were also illustrated.