Author(s): Yuchun Wang; Mei Ma; Guibao Li; Huaidong Zhou
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Keywords: Reservoir; Nutrients regeneration; Sediment-water Interface
Abstract: Two adjacent large-size reservoirs, the Wujiangdu reservoir (WJDR) and the Dongfeng reservoir (DFR), both located on the main stream of the Wujiang River, were selected for a comparative study on nutrient regeneration near the sediment-water interface and nutrient flux across the sediment-water interface into the overlying water column. Water, pore water and sediment were collected from these two reservoirs and dissolved organic carbon (DOC), NH4 +, NO 3 -, PO 4 3-, dissolved silica (DSi) were measured in the overlying water and pore water. Sedimentary particulate organic carbon (POC) and particulate organic nitrogen (PON) abundance and N/C ratios were determined from sediment core samples. Results from the two reservoirs show that processes of nutrient regeneration near the sediment-water interface are significantly different. As a result of rapid decomposition of algae-derived “labile” organic matter in upper sediments, nutrient regeneration and upward flux is significantly larger in WJDR than in DFR: NH4+upward flux from sediment in WJDR was about 17 times higher than that in DFR; PO 4 3- flux in WJDR was about 13 times above that in DFR; DOC flux in WJDR was 5 times larger than in DFR and DSi higher by 1time. Our data also show that relative larger amount of Sedimentary OC (33%), nitrogen (43%) and phosphorus (79%) were removed from the sediments during its burial history in WJDR; while results are relative lower for DFR with the removal of sedimentary OC (4.5%), N (11%) and P (33%).
Year: 2004