Study on temporal and spatial variations of excessive dissolved phosphorus in the Fuquan section of the Chong-an River

ABSTRACT There were many phosphorus chemical enterprises and phosphogypsum slag fields in the Fuquan section of the Chong-an River in the Guizhou Province of China; therefore, the dissolved phosphorus in the Fengshanqiaobian water quality monitoring section of the area has exceeded 0.2 mg/L for a long time. This study analyzed the monitoring data of dissolved phosphorus, fluoride, nitrate–nitrogen, and chemical oxygen demand in the main stream and key tributaries of the Fuquan section of the Chong-an River from 2015 to 2021, in which the main exceeding factor was dissolved phosphorus of more than 0.2 mg/L; determined the variation law of phosphorus pollution in the water body of the Fuquan section of the Chong-an River, in which the exceedance of phosphorus was mainly concentrated in May of flood season and in January and March of the drought season; evaluated the sources of phosphorus pollution, in which the main pollution sources were from phosphogypsum slag field leakage, phosphorus chemical industry plant leakage, agricultural nonpoint source pollution; and presented measures to reduce phosphorus pollutants in rivers, such as strengthening phosphogypsum slag field and phosphorus chemical enterprise seepage prevention measures, and reducing the amount of phosphate fertilizer application.