高原深水湖泊程海中氮元素时空分布特征

采用GPS定位,在程海设置了3个断面9个采样站14个采样点,对氮元素及其赋存形态进行了为期1年的动态研究。结果表明:总氮(TN)浓度范围0.490~2.827 mg/L之间,平均0.773 mg/L,赋存形态及其组成为:溶解态总氮(DTN)占TN含量的64.3%;颗粒态总氮(PTN)占TN的35.7%;溶解态有机氮(DON)占TN的53.3%;溶解态无机氮(DIN)占TN的11.0%;氨态氮(NH3-N)占TN的6.9%;硝态氮(NO3--N)占TN的3.4%;亚硝态氮(NO2--N)占TN的0.8%,使湖泊具备富营养化易发条件。氮素形态转化及其年内时间分布特征与浮游植物生长、衰老、死亡、分解等生命活动的周期变化密切相关。空间分布格局受浮游生物活动、湖流风动、湖水补给和水化学特征等综合影响。文章为认识高原深水湖泊水中氮赋存形态、时空分布及其动态变化提供资料,为揭示氮素生物地球化学循环过程和蓝藻水华爆发的内在联系提供参考。

Spatial and Temporal Distribution of Nitrogen in Lake Chenghai,a Deep Plateau Lake

Lake Chenghai,a typical plateau lake of average depth of 26.5 m,was studied on the basis of field survey about its water quality in terms of nitrogen speciation,which involved dissolved total nitrogen(DTN),particle total nitrogen(PTN),dissolved organic nitrogen(DON),dissolved inorganic nitrogen(DIN),NH3-N,NO3——N,and NO2——N.The proportions of different forms of nitrogen revealed by the study indicated that the lake was vulnerable to eutrophication.The transformation of nitrogen and annual spatio-temporal distribution closely related to the phytoplankton’s growth,senescence,death and decomposition.It was found that the spatial pattern of nitrogen was in general affected by the activity of plankton,lake water movement caused by the water currents and wind,as well as the characteristics of hydrochemistry of lake water.Results of the study would provide references for probing into the inner rules governing the biogeochemical cycle of nitrogen and potential blue-green algal blooms.