汾河下游土地利用类型对河流无机氮的影响

Influence of Land Use Types on Inorganic Nitrogen in the Lower Reaches of Fenhe River

为研究汾河下游沿岸近域土地利用类型对河流水体无机氮浓度的影响,基于2018年7月、12月汾河下游9个断面无机氮指标数据和2018年Landsat TM/ETM遥感数据,利用相关分析和冗余分析等方法对土地利用类型与无机氮浓度的关系进行了研究。结果表明:汾河下游无机氮污染严重,NH_(4)^(+)-N浓度高于地表水Ⅴ类水标准;丰水期近岸土地利用类型对水体无机氮浓度的影响比枯水期的大;在300、500、1000、1500 m缓冲带下,不同水期,NO_(3)^(-)-N和NH_(4)^(+)-N浓度与耕地、城乡建设用地、林地、草地面积存在一定相关性,体现了耕地对NO_(3)^(-)-N起“源”的作用,耕地和城乡建设用地对NH_(4)^(+)-N起“源”的作用,林地和草地对NO_(3)^(-)-N和NH_(4)^(+)-N起“汇”的作用。

In order to study the influence of the near⁃land land use structure to the water body inorganic nitrogen concentration along the low⁃er reaches of the Fenhe River,based on the inorganic nitrogen index data of 9 sections in July and December 2018 and the Landsat TM/ETM remote sensing data of the summer of 2018,the relationship between the land use patterns and inorganic nitrogen concentration was studied by means of correlation analysis and redundant analysis.The results show that the inorganic nitrogen pollution in the lower reaches of the Fenhe River is serious and the NH_(4)^(+)-N concentration is higher than that of water standard V.The wet period of the nearshore land structure has a greater impact on the inorganic nitrogen in the water than that of the dry season.At the buffer zones of 300 m,500 m,1000 m and 1500 m,the NO_(3)^(-)-N and NH_(4)^(+)-N indicators are positively correlated with the cultivated land and urban and rural land in different water periods,but negatively correlated with forest land and grassland,reflecting cultivated land.The role of NO_(3)^(-)-N is“source”.The cultivated land and urban and rural construction land play the role of“source”for NH_(4)^(+)-N,and the woodland and grassland play the role of“converge”for NO_(3)^(-)-N and NH_(4)^(+)-N.