Nutrient release flux in Baiyangdian Lake with high disturbance

Abstract

The cause analysis of overlying water eutrophication in high-disturbance areas is conducive to effective control measures. This paper analyzed the release risk and water quality of ammonia nitrogen (NH 3 –N) and orthophosphate (PO + 4 –P) in sediments of typical high-disturbance areas of Baiyangdian Lake and assessed the impact posed by the exchange flux of ammonia nitrogen and orthophosphate in sediments to the overlying water. The sediments in Nanliuzhuang and Caiputai fishponds were seriously polluted by nitrogen and phosphorus, respectively. The concentrations of NH 3 –N and PO + 4 –P in surface sediment pore water in the two lakes were significantly higher than those in the overlying water. Diffusion fluxes of NH 3 –N and PO + 4 –P were 1.89–3.38 and 0.99–3.05 mg m −2 d −1 at the sediment–water interface of fishponds in Nanliuzhuang district. Diffusion fluxes of NH 3 –N and PO + 4 –P at the sediment–water interface of fishponds in the Caiputai area separately ranged from −0.15 mg m −2 d −1 to 2.19 mg m −2 d −1 and from 0.41 mg m −2 d −1 to 2.14 mg m −2 d −1 , respectively. Results showed that fishpond sediment is an important source of orthophosphate in the overlying water. The overlying water NH 3 –N mainly comes from external inputs, such as bait feeding. Identification of key areas of endogenous risk and control of sediment NH 3 –N and PO + 4 –P endogenous release are the key links of water pollution control in Baiyangdian Lake.