金佛山地区地下水硝态氮污染时空变异性研究

根据1976～1977年、2004～2006年和2009年金佛山地区23处地下水排泄点水中硝态氮的质量浓度,采用地球化学、统计学与GIS相结合的方法确定了区内地下水中硝态氮的地球化学背景值,分析了硝态氮污染的时空变异特征.结果表明,区内地下水中硝态氮的地球化学背景值为0.72～2.00 mg.L-1,正异常下限为3.20 mg.L-1;2004～2006年和2009年金佛山自然保护区内地下水硝态氮平均质量浓度为：2.08、2.67、2.59和3.92 mg.L-1;保护区外为：39.08、25.46、17.99和13.73mg.L-1;平均超标率（标准规定NO 3--N≤10 mg.L-1）为：451.64%、478.61%、331.85%和145.67%;最高浓度为：157.58、118.04、63.82和46.18 mg.L-1;最大超标率为：1 475.81%、1 080.39%、538.20%和361.78%.插值分析结果显示,区内地下水中硝态氮高值中心随时间而变化,低值区沿金佛山自然保护区分布.当地合理的环境保护政策和产业结构调整,对环境保护工作起到了积极作用.

Spatial and Temporal Variability of Nitrate Contaminant in Groundwater in Jinfo Mt. Area, Chongqing, China

The geochemical background of nitrate in groundwater in Jinfo Mt. area was determined, and spatial and temporal variability of nitrate contaminant was analyzed using geochemical, statistical and GIS methods. Twenty-three samples were collected from groundwater discharge points in the study area during 1976-1977, 2004-2006 and 2009, and mass concentration of nitrate in groundwater was tested. The results showed that the geochemical background of nitrate in groundwater in study area was in the range of 0.72-2. 00 mg x L(-1), and the threshold of anomaly was 3.20 mg x L(-1). During 2004-2006 and 2009, the average values of nitrate concentration in groundwater in Jinfo Mt. natural reserve were 2.08, 2.67, 2.59 and 3.92 mg x L(-1); and were 39.08, 25.46, 17.99 and 13.73 mg x L(-1) in the groundwater out of the reserve; the average over-limit rates (standard limit NO3(-) -N < or = 10mg x L(-1)) were 451.64%, 478.61%, 331.85% and 145.67%; the maximum over-limit rates were 1 475.81%, 1 080.39%, 538.20% and 361.78%. Results of interpolation showed that the high value centers of nitrate concentration in groundwater in study area were changing over time, but districts with low nitrate concentration in groundwater in study area were distributed along Jinfo Mt. natural reserve. The application of environmental policy measures and industrial restructuring implemented were reasonable and successful, which had a positive effect to environmental protection.