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Dynamics of sediment resus-pension and the conceptual schema of nutrient release in the large shallow Lake Taihu,China

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Chinese Science Bulletin 2004年第1期49卷 54-64页

作者： QINRoqiang HUWeiping GAOGuang luoliancong ZHANGJinshan NanjingInstituteofGeographyandLimnology ChineseAcademyofSciencesNanjing210008China NanjingInstituteofHydrologicalSciences MinistryofWaterConservancyandMinistryofTransportationNanjing210024China

On the basis of investigations in situ, it was found that mass exchange on the water-sediment interface occurred chiefly on the superficial sediment within 5-10 *** spatial physicochemical character of sediment was distributed uniformly. The observation of lake currents and waves indicated that the dynamic sources, which act on the interface of water and sediment, came mainly from waves under strong wind forcing, while the critical shear stresses due to the waves and currents were of the same magnitude under weak wind forcing. The critical shear stress that leads to extensive sediment resuspension was about 0.03-0.04N/m2, equivalent to a wind speed in situ up to 4 m/s. If a dynamic intensity exceeded the critical shear stress, such as a wind velocity up to 6.5 m/s, massive sediment re-suspension would be observed in the lake. Furthermore, field investigations revealed that the nutrient concentration of pore water within the sediment was far greater than that of overlaying water, which provides objective conditions for the nutrient release from sediment. According to nutrient analyses in the pore water from the superficial 5-10 cm sediments, a severe dynamic process in the Taihu Lake would bring out a peak nutrient release, i.e. a 0.12 mg/L increase of TN, and 0.005mg/L increase of TP in the lake. In the end, a general scheme of nutrient release from sediment in large shallow lakes was put forward: when the wind-driven forcing imposes on the lake, it will make the sediment resuspension. At the same time, the nutrition from the pore water will follow the sediment resuspension release to overlaying water. Because of oxidation of solid particulates when it resuspends from sediment, the disturbance of hydrodynamics will enhance thesuspension particulates absorbing nutrition. After the withdrawal of wind forcing, the suspended mass would deposit and bring part of the released nutrients back into *** degraded organic particulate would be separated to the pore w

关键词：动力学太湖中国沉积再悬浮生态修复

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A vertically integrated eutrophication model and its application to a river-style reservoir-Fuchunjiang,China

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Journal of Environmental Sciences 2009年第3期21卷 319-327页

作者： WU Tingfeng luoliancong QIN Boqiang CUI Guangbai YUZuoming YAO Zhiming State Key Laboratory of Lake Science and Environment Nanjing Institute of Geography & Limnology Chinese Academy of Sciences Nanjing 210008 China College of Hydrology and Water Resources Hohai University Nanjing 210098 China Hangzhou Research Institute of Environmental Sciences Hangzhou 310014 China Administrative Division of Qingshan Reservoir Hangzhou 311305 China

Based on a 2-D hydrodynamic model, a vertically integrated eutrophication model was developed. The physical sub-model can be used for calculation of water density at different depths, and the water quality sub-model was used for calculation of algal growth. The cohesive and non-cohesive sediments were simulated separately with different methods. The light extinction coefficient used in the underwater light regime sub-model was linearly related to the sum of sediment and phytoplankton biomass. Some components less important to the model were simplified to improve practicability and calculation efficiency. Using field data from Fuchunjiang Reservoir, we calculated the sensitivity of ecological parameters included in this model and validated the model. The results of sensitivity analysis showed that the parameters strongly influenced the phytoplankton biomass, including phytoplankton maximum growth rate, respiration rate, non-predatory mortality rate, settling rate, zooplankton maximum filtration rate, specific extinction coefficient for suspended solids and sediment oxygen demand rate. The model was calibrated by adjusting these parameters. Total chlorophyll α （chl-α） concentrations at different layers in the water column were reproduced very well by the model simulations. The simulated chl-α values were positively correlated to the measured values with Pearson correlation coefficient of 0.92. The mean difference between measured and simulated chl-α concentrations was 12% of the measured chl-α concentration. Measured and simulated DO concentrations were also positively correlated （r = 0.74） and the mean difference was 4% of measured DO concentrations. The successful validation of model indicated that it would be very useful in water quality management and algal bloom prediction in Fuchunjiang Reservoir and a good tool for water quality regulation of other fiver-style reservoirs.

关键词： fiver-style reservoir eutrophication numerical model Fuchunjiang Reservoir

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