Abstract:

To investigate the spatial distribution of groundwater nitrate nitrogen (NO-3N) in the Chao Lake watershed, 253 water samples were collected from wells in the watershed from November to December, 2009 and their NO-3N concentrations were analyzed. The results showed that the samples NO-3N concentrations were averaged 7.13 mg/L, and 15.81% of them exceeded 10 mg/L, the WHO limit for NO-3N of drinking water, and 7.11% of them exceeded 20 mg/L, the criterion for serious NO-3N pollution. The NO-3N concentrations were different in different land types, with the pattern of villages>vegetable fields>fruit gardens>dry lands>towns>ricerape (or wheat) fields>singleseason rice fields>livestock farms. The NO-3N concentration of groundwater in Green RiceProducing Area was lower than that in NonGreen RiceProducing Area in Chao Lake watershed. The NO-3N concentration of groundwater in farmlands was positively related to the application rate of nitrogen chemical fertilizer, the population density and the proportion of cultivated area. The  NO-3N concentrations were declined with the lowering of the groundwater table, but there was no significant correlation between them. When the application of chemical fertilizer nitrogen exceeds 100 kg/hm2, or the groundwater table is less than 9 m, the NO-3N concentration of groundwater has the potential risk of exceeding the WHO limit.

Key words: the Chao Lake watershed, groundwater, nitrate nitrogen

摘要：

为了探讨巢湖流域地下水硝态氮的空间分布规律,2009年11月至12月在巢湖流域采集了253个地下水样品,分析了其硝态氮含量。结果表明,巢湖流域地下水硝态氮含量平均值为7.13 mg/L,超标率(10 mg/L≤NO-3N<20 mg/L)和严重超标率(NO-3N≥20 mg/L)分别为15.81%和7.11%。不同土地类型的地下水硝态氮含量存在一定差异，其中村庄＞菜地＞果园＞旱地＞城镇＞水稻-油菜（或小麦）轮作田＞单季水稻田＞养殖场。巢湖流域绿色水稻产区地下水硝态氮含量比非绿色水稻产区低。农田地下水硝态氮含量与化肥氮施用量、人口密度和耕地面积比例呈正相关。农田地下水硝态氮含量具有随地下水位的下降而降低的趋势，但两者之间没有显著相关性。当化肥氮的年施用量超过100 kg/hm2或地下水位低于9 m时，地下水硝态氮含量存在超标的潜在危险。

关键词: 巢湖流域;地下水;硝态氮