Sediment phosphorus fraction and release potential in the major inflow rivers of Chaohu Lake, Eastern China
2019
Zhang, Ruiming | Yin, Aijing | Gao, Chao
Surface sediment samples from nine inflow rivers of Chaohu Lake in Eastern China were analyzed by the sequential extraction procedure and the zero equilibrium phosphorus concentration (EPC₀) was determined to evaluate the behavior of phosphorous at the water–sediment interface. The results reveal that substantial amounts of P had accumulated in river sediments from agricultural runoff and domestic sewage. For most of the sample sites, the total P content was higher in sediments from urban rivers than in those from rural rivers. On average, the reactive inorganic P consisted of slightly more than 60% of the total P, with Fe-P being the dominant P form. Compared with rural sediments, the Al-P contents were significantly higher in urban sediments, while the Res-P contents were significantly lower. The differences can be attributed to the differential discharge of P from watersheds with contrasting land uses and to the dramatic changes in the ambient conditions of urban rivers. A higher soluble reactive phosphorus (SRP) value of the overlying water relative to the EPC₀ value in the mouth of the urban rivers of Chaohu Lake indicates that bottom sediments still play a role in adsorbing phosphorus from the water column before it reaches Chaohu Lake.
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