Phosphorus in the Sediments of Yangzong Lake, China
2020
Yuxi Zhang, Bing Zhou and Jiansheng Shi
Total 150 sediments samples were collected from the Yangzong Lake, and the total phosphorus, pH, redox potential and organic carbon were analysed to quantitatively study the dispersal and sources of phosphorus and its influential factors. The results indicated that the total phosphorus content in sediments was 318-3931 mg/kg, which decreased slightly with depth. In the sediments at the depths of 0-2cm, 2-4cm, 4-6cm, 6-8cm and 8-10cm, the phosphorus contents were 1151mg/kg, 1126mg/kg, 1138mg/kg, 1057mg/kg and 893mg/kg respectively. The contents of phosphorus in the sediments were high on both north and south banks and reduced gradually towards the centre of the lake. Before the 1980s, the phosphorus distribution in the sediments was mainly influenced by natural factors such as pH value, redox potential and organic matter. But after the 1980s, the phosphorus distribution was mainly affected by the position of sewage discharge. Sources of phosphorus in the sediments have changed from the local source to the multiple sources, and from the point source to surface source. Currently, soil erosion and agricultural non-point source pollution are the main sources of phosphorus in Yangzong Lake.
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