洱海表层水体中氮素空间变异分析

基于地理信息系统与地统计学技术,对洱海表层水体中不同形态氮素空间变异特征进行了分析。结果表明:洱海表层水体中不同形态氮呈现自南向北逐步增高的空间变化特征;NO3--N质量浓度高值出现在洱海南部区域;溶解性氮和TN质量浓度在洱海中部地区出现高值区;NH4+-N在弥苴河江口及万花溪入洱海处出现两处高值区。TN质量浓度数值差异较大,变异系数为34.84%;NH4+-N、溶解性氮和TN在空间分布上除了受湖水流速、水文情势、水动力学性质、水文气象等结构性因素的控制以外,还受到外来污染、水利工程控制、用排水等人类活动的随机性因素影响。

Analysis on spatial variation of nitrogen in top layer water of Erhai Lake

Based on geographical information systems and geostatistical analysis technology, the spatial variation of nitrogen in different forms in the top layer water of Erhai Lake was studied. The different forms of nitrogen in the top layer gradually increased from south to north. A region of high NO3^--N content appeared in southern Erhai Lake, the high mass concentration of dissolved nitrogen and TN appeared in the middle of Erhai Lake, and the NH4^＋ -N had two high value regions in Erhai Lake, in the estuaries of the Miju River and the Wanhuaxi River. The spatial difference in TN mass concentration was large and the variation coefficient was 34.84%. The spatial variation of NH4^＋-N, dissolved nitrogen, and TN was mainly caused by some construction factors such as flow velocity, hydrologic patterns, hydrodynamic properties and hydro-meteorology, and was also affected by some random factors such as external pollution, regulation of hydraulic engineering, water consumption, and drainage. This study has contributed to water quality protection, eutrophication mechanism study, and comprehensive water environment prevention of Erhai Lake.