Atmospheric deposition of nitrogen and phosphorous in Lake Yangzonghai,Yunnan Prov-ince

Abstract

大气氮、磷沉降是湖泊水体氮、磷入湖的重要途径之一.为了解阳宗海氮、磷沉降对湖泊富营养化的潜在影响，于2012年5月-2014年4月通过监测阳宗海大气氮、磷沉降，估算氮、磷的大气沉降通量，揭示阳宗海大气氮、磷沉降随时间变化的特征，分析其来源、影响因素等.由于阳宗海是磷限制湖泊，本研究在估算大气氮、磷沉降通量的基础上，特别比较了大气磷沉降入湖量与非点源磷的入湖量，以此评估大气沉降输入磷对湖泊富营养化的潜在影响.研究结果表明：阳宗海总氮年平均沉降通量为248 mg/m²，春、夏、秋和冬季平均分别为200、306、274和214 mg/m²，其中夏季沉降通量最大，原因与降雨量增加有关；总磷年平均沉降通量为24 mg/m²，春、夏、秋和冬季平均分别为18、31、19和27 mg/m².大气磷沉降与输入阳宗海的总磷量相比很小，对阳宗海富营养化影响较小.;Atmospheric deposition is one of the important pathways for nitrogen (N) and phosphorus (P) transported into lakes.To understand the potential impact of N and P from atmospheric depositions on the eutrophication of Lake Yangzonghai,this re-search investigated the temporal variation and estimated the fluxes of N and P from atmospheric depositions in the lake catchment.The sources and impact factors of the N and P depositions were analyzed by monitoring data from May 2012 to April 2014.Since Lake Yangzonghai is a P-limited lake,this study especially compared the P fluxes from N and P atmospheric deposition with that from non-point sources,and assessed the potential P-impact from atmospheric deposition on the eutrophication lake.The results showed that the average annual deposition flux of total nitrogen was 248 mg/m²,and seasonal deposition fluxes in spring,summer,autumn and winter were 200,306,274 and 214 mg/m²,respectively.The peak of N flux occurred in summer because of the in-creased rainfall.The annual average P deposition flux was 24 mg/m²,and seasonal deposition fluxes in spring,summer,autumn and winter were 18,31,19 and 27 mg/m²,respectively.Compared with the non-point P-load source,P-input from atmospheric deposition seemed very small,and would have little effect on the eutrophication of the lake.