Contamination status and speciation for the sediment nutrients in Panjiakou-Daheiting Reservoir

Abstract

As the source of the "Luanhe-Tianjin Diversion Project", water environment status in the Panjiakou-Daheiting Reservoir directly affects drinking water safety in the water receiving area, and therefore plays important role in the development of the Beijing-Tianjin-Hebei region. Field survey was carried out in July 2016 to examine the pollution status of the sediment nitrogen, phospho-rus and organic matter. The results showed that total nitrogen (TN) content of surface sediments in Panjiakou-Daheiting Reservoir ranged from 1175.41 to 2415.67 mg·kg-1 with a mean of 1648.71 mg·kg-1. Total phosphorus (TP) ranged from 1773.25 to 3471.70 mg·kg-1 with a mean of 2790.89 mg·kg-1. Organic matter (OM) ranged from 6.0% to 25.3% with a mean of 12.5%. Daheiting Reservoir which located downstream of Panjiakou Reservoir had higher value in TP content, while had similar TN content. Results from speciation analysis showed that sediment nitrogen was mainly composed of organic nitrogen and phosphorus mainly consisted of calcium-phosphorus which belonged to inorganic phosphorus. The value of C/N ratio indicated that OM mainly originated from exogenous substances. The pollution assessment results demonstrated that the sediment Panjiakou-Daheiting Reservoir was in a severe pollution status, and might have potential effect to the water environment improvement through the nutrient exchange at the sediment-water interface.