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Sheng H.,Nanjing Forestry University | Sheng H.,Hangzhou Institute of Environmental Protection Science | Wu Z.,Chunan Environmental Monitoring Station | Liu M.,Hangzhou Institute of Environmental Protection Science | And 4 more authors.
Huanjing Kexue Xuebao/Acta Scientiae Circumstantiae | Year: 2015

Based on the monthly water quality monitoring data and hydro-meteorological data from 2003 to 2012, this study analyzed water quality and nutritional status in Xin'anjiang reservoir and investigated the relationship between water quality change and hydro-meteorological factors. The results showed that the interannual variability of total phosphorus, total nitrogen, BOD and pH value were significant in the past 10 years in Xin'anjiang Reservoir. Chlorophyll a concentration increased in recent 10 years. Comprehensive nutrition state index showed that the reservoir trophic status was improved gradually from oligotrophic to mesotrophic. Nutrient and chlorophyll a was higher in riverine zone than transitional and lacustrine zone and in flooding season than dry season, which indicated that reservoir nutrients came mainly from non-point source pollution. The mean annual air temperature and water temperature decreased, while rainfall, out flow and in flow increased. The correlation analysis showed that hydro-meteorological factors had significant impacts on water quality index. ©, 2014, Science Press. All right reserved. Source

Wu Z.,Chunan Environmental Monitoring Station | Zhang Y.,CAS Nanjing Institute of Geography and Limnology | Zhou Y.,CAS Nanjing Institute of Geography and Limnology | Zhou Y.,University of Chinese Academy of Sciences | And 3 more authors.
International Journal of Environmental Research and Public Health | Year: 2015

Water transparency is a useful indicator of water quality or productivity and is widely used to detect long-term changes in the water quality and eutrophication of lake ecosystems. Based on short-term spatial observations in the spring, summer, and winter and on long-term site-specific observation from 1988 to 2013, the spatial, seasonal, long-term variations, and the factors affecting transparency are presented for Xin’anjiang Reservoir (China). Spatially, transparency was high in the open water but low in the bays and the inflowing river mouths, reflecting the effect of river runoff. The seasonal effects were distinct, with lower values in the summer than in the winter, most likely due to river runoff and phytoplankton biomass increases. The transparency decreased significantly with a linear slope of 0.079 m/year, indicating a 2.05 m decrease and a marked decrease in water quality. A marked increase occurred in chlorophyll a (Chla) concentration, and a significant correlation was found between the transparency and Chla concentration, indicating that phytoplankton biomass can partially explain the long-term trend of transparency in Xin’anjiang Reservoir. The river input and phytoplankton biomass increase were associated with soil erosion and nutrient loss in the catchment. Our study will support future management of water quality in Xin’anjiang Reservoir. © 2015 by the authors; licensee MDPI, Basel, Switzerland. Source

Yin Y.,Hangzhou Institute of Environmental Science | Wu Z.-X.,Chunan Environmental Monitoring Station | Zhang Y.-L.,CAS Nanjing Institute of Geography and Limnology | Liu M.-L.,Hangzhou Institute of Environmental Science | And 4 more authors.
Zhongguo Huanjing Kexue/China Environmental Science | Year: 2014

To investigate the spectral absorption characteristics, spatial distribution and source of colored dissolved organic matter (CDOM), 53 surface water samples were collected from Xin'anjiang Reservoir in July, 2013.The spatial distribution of CDOM absorption coefficient at 350 nm[a(350)], carbon-specific CDOM absorption coefficient [a*(350)], the spectral slope (S), as well as the relationships between CDOM and water quality parameters were studied. Using hierarchical cluster analysis, we divided a(350) into three districts (A, B, and C districts). a(350) decreased from north western area (A district) to the central reservoir and the north eastern area (B district), and to the south western area and the south eastern area (C district). The distribution pattern of a (350) was similar to the distribution of a*(350) but different from that of S. Significantly positive linear correlations between a (350) and chlorophyll a concentration, phytoplankton absorption coefficient and suspended solids indicated a critical contribution of phytoplankton metabolism and degradation products of CDOM. ©, 2014, Chinese Society for Environmental Sciences. All right reserved. Source

Dong C.-Y.,Zhejiang GongShang University | Yu Z.-M.,Hangzhou Institute of Environmental Protection Science | Wu Z.-X.,Chunan Environmental Monitoring Station | Wu C.-J.,Zhejiang GongShang University
Huanjing Kexue/Environmental Science | Year: 2013

Lake Qiandao is a typical subtropical man-made reservoir in China. The investigation on the seasonal and vertical dynamics of water temperature, dissolved oxygen (DO), pH value, turbidity, photosynthetic available radiation (PAR) and chlorophyll a was conducted in 2011 in order to find out the physical characteristics of Lake Qiandao. The average surface water temperature ranged from 10.4 to 32.7°C. A monomictic thermal stratification was observed in Lake Qiandao, initiating in April and lasting until December. The results showed that thermal stratification had influences on vertical distribution of DO, pH value, turbidity, PAR and chlorophyll a. Very strong stratification of DO was found, inducing lower oxygen concentration in the thermocline layer and temporal hypoxia in the bottom water. The maximum turbidity was found in the thermocline layer and the precipitation affected the surface turbidity value. Moreover, the chlorophyll a concentration was higher in the surface water and lower in the bottom water as found in this study, implying that water quality was affected by stratification. Besides, the maximum photosynthesis rate and algal growth rate were found at the depth 5-10 m below the water surface. Therefore, the results can provide theoretical support for the sampling and analysis of algal blooms in Lake Qiandao. Source

Zhang Y.,CAS Nanjing Institute of Geography and Limnology | Wu Z.,Chunan Environmental Monitoring Station | Liu M.,Institute of Environmental Protection Science | He J.,Institute of Environmental Protection Science | And 7 more authors.
Water Research | Year: 2015

From January 2010 to March 2014, detailed depth profiles of water temperature, dissolved oxygen (DO), and chromophoric dissolved organic matter (CDOM) were collected at three sites in Lake Qiandaohu, a large, deep subtropical reservoir in China. Additionally, we assessed the changes in DO stratification over the past 61 years (1953-2013) based on our empirical models and long-term air temperature and transparency data. The DO concentration never fell below 2mg/L, the critical value for anoxia, and the DO depth profiles were closely linked to the water temperature depth profiles. In the stable stratification period in summer and autumn, the significant increase in CDOM in the metalimnion explained the decrease in DO due to the oxygen consumed by CDOM. Well-developed oxygen stratification was detected at the three sites in spring, summer and autumn and was associated with thermal stratification. Oxycline depth was significantly negatively correlated with daily air temperature and thermocline thickness but significantly positively correlated with thermocline depth during the stratification weakness period (July-February). However, there were no significant correlations among these parameters during the stratification formation period (March-June). The increase of 1.67°C in yearly average daily air temperature between 1980 and 2013 and the decrease of 0.78m in Secchi disk depth caused a decrease of 1.65m and 2.78m in oxycline depth, respectively, facilitating oxygen stratification and decreasing water quality. Therefore, climate warming has had a substantial effect on water quality through changing the DO regime in Lake Qiandaohu. © 2015 Elsevier Ltd. Source

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