贵州草海岩溶湿地水体不同形态氮的时空分布特征

为揭示贵州草海岩溶湿地水体中不同形态氮时空分布特征及其变化规律,通过网格布点法采集了该湿地丰、枯水期表层水,并对其不同形态溶解性氮含量进行了测定,运用ArcGIS统计模块分析了草海不同形态氮的时空分布特征,并分析了各形态氮与环境因子之间的相关性.结果表明:草海水体丰、枯水期TN的平均含量分别为(0.96±0.52)、(...

Temporal and spatial distribution characteristics of different forms of nitrogen in karst wetland in Caohai,Guizhou

To explore the spatiotemporal distribution and variation characteristics of different forms of nitrogen in karst wetland of Caohai,Guizhou Province,we collected surface water samples in wet and dry seasons using a grid distribution method,and measured the concentrations of dissolved nitrogen with different forms.The spatial and temporal distribution of the different nitrogen forms were analyzed by using Arc GIS statistical module.The correlation between various forms of nitrogen and environmental factors was analyzed.The results showed that the average concentrations of total nitrogen (TN) in Caohai were (0.96±0.52) mg·L^-1in the wet season and (0.90±0.71) mg·L^-1in the dry season,with higher concentrations of TN in the wet period.Moreover,inorganic nitrogen was predominant in the wet period.The sum of NH4⁺-N and NO3^--N accounted for 54%of TN,with an average concentration of (0.14±0.08) and (0.38±0.56)mg·L^-1,respectively.The high values of these two forms of nitrogen were distributed in the west area,which was mainly affected by external import.In the dry season,organic nitrogen was the main form.The dissolved organic nitrogen accounted for 49%of TN,with an average concentration of (0.44±0.26) mg L^-1.Furthermore,the high value area appeared in the south area,as the water supply of Caohai decreased in the dry season,coupled with the decline of aquatic organisms and nitrogen release in sediments,which contributed to the release and transformation of nitrogen in water body.Therefore,the seasonal variation of nitrogen forms in Caohai Lake was mainly affected by water environmental changes,exogenous nitrogen input,and endogenous nitrogen release.Pollution control in three rivers entering the lake in Western Caohai should be strengthened in the wet season,while nitrogen release in lake sediments should be controlled in the dry season,to effectively reduce nitrogen concentration in water body of Caohai.