新疆喀什噶尔河流域平原区地下水“三氮”含量分布特征及影响因素分析

Spatial distribution and influencing factors of “three-nitrogen”of groundwater in the plain of Kashgar River basin, Xinjiang

地下水"三氮"污染已成为全球性环境问题.本文基于新疆喀什噶尔河流域2014年62组地下水采样点中"三氮"含量进行分析.结果表明,研究区地下水NO3--N含量未超标,仅个别采样点存在NO2--N、NH4+-N超标现象;地下水NO3--N含量范围ND—12.42 mg·L^(-1),NO2--N含量范围ND—1.21 mg·L^(-1),NH4-N含量范围ND—77.78 mg·L^(-1).水平方向上NO3--N和NH4+-N含量总体分布呈南高北低,NO2--N含量总体分布呈北高南低.垂直方向上山麓斜坡冲洪积砾质平原潜水区NO3--N、NO2--N含量表现为深层潜水大于浅层潜水,NH4+-N含量表现为浅层潜水大于深层潜水;河流冲积平原承压水区NO3--N含量表现为浅层承压水大于深层承压水,NO2--N、NH4+-N含量表现为深层承压水大于浅层承压水.影响研究区"三氮"含量主要因素有包气带岩性结构、地下水位埋深、地下水氧化还原环境、偏碱性环境、土地利用类型等.

Groundwater"Three-Nitrogen"pollution had become a global environmental problem.This paper analyzed"There-Nitrogen"concentration of 62 sampling wells in 2014 in the plain of Kashgar river basin of Xinjiang.The results showed that the NO3--N concentration in groundwater was not exceed the standard,the concentrations of NO2--N and NH4+-N were exceed the standard in only a few sampling points in the study area.The concentration of NO3--N ranged from ND to 12.42 mg·L^(-1).The concentration of NO2--N ranged from ND to 1.21 mg·L^(-1).The concentration of NH4+-N range from ND to 77.78 mg·L^(-1).In the horizontal direction,the concentrations of NO3--N and NH4+-N in the south of the study area were higher than that in north of the study area.The concentration of NO2--N in the north of the study area was higher than that in south of the study area.In vertical direction,the concentrations of NO3--N and NO2--N in deep unconfined groundwater were higher than that in shallow unconfined groundwater.The concentration of NH4+-N in shallow unconfined groundwater was higher than that in deep unconfined groundwater in piedmont slope alluvial gravel plain area.The concentration of NO3--N in shallow confined groundwater was higher than that in deep confined groundwater.The concentrations of NH4+-N and NO2--N in deep confined groundwater were higher than that in shallow confined groundwater in alluvial plain area in middle and lower reaches of the rivers.The main factors affecting the distribution characteristic of concentration of"Three-Nitrogen"were lithology of vadose zone,buried depth of groundwater,redox conditions,alkaline environment and land use types in the study area.