Comparison of nitrogen and phosphorus exchange fluxes at the sediment-overlying water interfaces of Daye Lake between winter and summer
In this work,the static incubation experiments of mud columns were used to compare the exchange fluxes of nitrogen and phosphorus at the sediment-overlying water interfaces of Daye Lake in winter and summer.The potential contribution of interfacial exchange to the nitrogen and phosphorus in the water body was then estimated,and the source or sink role of sediment was also discussed.Finally,the effects of disturbance,temperature,dissolved oxygen,and pH on the release of nitrogen and phosphorus were investigated through single-factor experiments.The results showed that the exchange fluxes and the source or sink role were different among the investigated sites between winter and summer.The exchange fluxes of nitrogen and phosphorus were the largest at point 1# of the lake in winter,and the average exchange fluxes of TN,NH4+-N,TP,and PO43--P were 202.94,41.62,0.55,and 0.36 mg·(m2·d)-1,respectively.The maximum nitrogen and phosphorus exchange fluxes were observed at point 3# of the lake outlet in summer,the average exchange fluxes of TN,NH4+-N,TP,and PO43--P were 389.27,89.54,1.79,and 1.18 mg·(m2·d)-1,respectively.In winter,the sediment acted as a source of TN and NH4+-N in the overlying water,and as a sink for TP and PO43--P in the overlying water.However,in summer the sediment acted as a source of TN,NH4+-N,TP,and PO43--P in the overlying water.Results of environmental factors analysis indicated that the resuspension fluxes of nitrogen and phosphorus increased with the increase of disturbance rate.High temperature and anaerobic conditions could promote the release of nitrogen and phosphorus from the sediment.The influence of water pH on nitrogen and phosphorus release was different,the release of nitrogen decreased with the increase of pH,while the release of phosphorus was the weakest at neutral pHs,but increased at acidic or alkaline pHs.This study is of great significance for clarifying the contribution of endogenous pollution to eutrophication in urban shallow lakes in the middle and lower reaches of Yangtze River,and for designing lake endogenous load control schemes as well as prevention and control of eutrophication in lakes.
Daye Lakesediment-overlying waternitrogen and phosphorusexchange fluxesinfluence factor
万方数据
维普
