Sources and Distribution of Phosphorus in Sediments of the Jinpen Reservoir

Abstract

In order to explore the sources and distribution of phosphorus in sediments of a stratified water source reservoir, the total phosphorus (TP) content and distribution of phosphorus fractions in sedimentation particles and sediments of the Jinpen Reservoir of Xi'an were analyzed from March to November in 2017. The results showed that the TP content in the surface sediments of the Jinpen Reservoir was obviously affected by the deposition of particulate phosphorus (PP), and the correlation coefficient was 0.8775. Besides, this TP pool was also affected by the biogeochemistry of sediments. From June to August, algae in the Jinpen Reservoir propagated intensely, and a large number of dead algae were deposited on the bottom of the water body, which resulted in a type of endogenous pollution dominated by algae. The concentration of PP reached (753.51±17.11) mg·kg-1, and the content of TP increased, with NaOH-nrP as the main component. During the flood season of the Jinpen Reservoir from September to November, the runoff water carried a large amount of sediments with large pollutant loads, which resulted in increases of the concentration of PP in the water body. However, the TP content in the sediment per unit mass was relatively small. As a result, the TP content of surface sediments decreased, with inorganic Ca-P and rest-P as the main forms, which accounted for 55.8%-66.2% of the TP in sediment, and were influenced by particle sedimentation. The SRP, BD-P, and NaOH-srP, the most active fractions, underwent a series of transport and transformation processes under the changing environmental conditions (mainly redox conditions), and these forms were obviously affected by the biochemical processes in sediments and minimally affected by the sedimentation processes of the reservoir.