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Li Y.,Key Laboratory of Integrated Regulation | Li Y.,Hohai University | Li Y.,Desert Research Institute | Acharya K.,Desert Research Institute | And 13 more authors.
Lake and Reservoir Management | Year: 2011

Lake Taihu, China's third largest freshwater lake, exemplifies the severity of eutrophication problems in rapidly developing regions.We used long term land use, water quality, and hydrologic data from 26 in-lake and 32 tributary locations to describe the spatiotemporal patterns in nutrient loads, nutrient concentration, algal biomass, measured as chlorophyll a (Chl-a), in Lake Taihu. Point and nonpoint sources, as determined by chemical oxygen demand, contributed approximately 75 and 25% of the total nutrient loads to the lake, respectively. Spatial patterns in total phosphorus (TP) and total nitrogen (TN) concentrations in Lake Taihu strongly corresponded with observed loads from adjoining rivers with high concentrations proximate to densely populated areas. Chl-a concentrations exhibited spatial patterns similar to TP and TN concentrations. Generally, nutrient and Chl-a concentrations were highest in the northwestern region of the lake and lowest in the southeastern region of the lake. Seasonally, the largest nutrient loads occurred during summer. The annual net retention rate of TP and TN in Lake Taihu was approximately 30% of the total load. This study identifies regions of the lake and the watershed that are producing more nutrients to develop targeted management strategies. Reducing external P and N input from both point and nonpoint sources is obviously critical to address water quality issues in the lake. In addition, atmospheric deposition and resuspension of existing lake sediments also likely play a role in eutrophication processes and harmful algal blooms occurrence. © Copyright by the North American Lake Management Society 2011.

Wang H.,China Institute of Water Resources and Hydropower Research | Zhang S.,Key Laboratory of Integrated Regulation | Zhang S.,Hohai University | Zhang W.,Key Laboratory of Integrated Regulation | And 5 more authors.
African Journal of Biotechnology | Year: 2010

To investigate the effect of exogenous Nitric oxide (NO) on submerged plants, Hydrilla verticillata (L.f.) Royle was treated with 25 - 400 μM sodium nitroprusside (SNP, a NO donor) for 0.5 - 4 d. The alterations in plant growth, H2O, total chlorophyll and malondialdehyde (MDA) content and the antioxidant response were assayed. The results showed that 25 - 100 μM SNP increased the plant growth and total chlorophyll content and reduced the level of H2O. However, an increase in H2O and MDA content and a decrease in total chlorophyll were detected in plants exposed to 200 - 400 μM SNP. The activity of catalase and peroxidase decreased in plants exposed to 25 - 400 μM SNP; and for superoxide dismutase, its activity was suppressed by the 25 and 50 μM SNP. The content of ascorbic acid and dehydroascorbate were also determined. The results provided the evidence that 25 - 100 μM SNP increased the growth of H. verticillata by alleviating the oxidative stress and 200 - 400 μM SNP might enhance the oxidative stress in plant cell. The results suggested that NO has dual role on the growth and ROS metabolism of Hydrilla verticillata (L.f.) Royle. © 2010 Academic Journals.

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