中文摘要：

为了研究节水工程改造及节水灌溉对区域农田地下水及硝态氮淋失污染的影响，以内蒙古河套灌区解放闸灌域为研究区域，对整个作物生长期的3月、5月、7月、9月分别取水样进行水化学和硝态氮测试分析。对2003年与2008年区域内27眼井地下水硝态氮的时空分布特征进行研究，结果表明：在2003年间，夏灌前解放闸灌域地下水硝态氮质量浓度大于10mg/L的面积占灌域总面积的9．95％，全年平均硝态氮质量浓度大于10mg／L的面积占灌域总面积的9．02％；2008年3月硝态氮质量浓度大于10mg／L的面积占灌域总面积的5．22％，全年平均硝态氮质量浓度大于10mg／L的面积占灌域总面积的5．20％。2003年与2008年的监测结果及时空分布趋势说明该地区地下水存在较严重的面源氮污染，但节水灌溉的实施可能对减少河套灌区的化肥淋失和地下水污染具有积极的改善作用，特别是由于秋浇水量的减少，地下水位下降，对减少地下水硝态氮污染具有明显的作用。

英文摘要：

In order to study the influence of reconstruction of water-saving projects and water-saving irrigation on the leaching pollution of nitrate nitrogen and groundwater quality in regional farmlands, the Jiefangzha irrigation area of Hetao irrigation district of Inner Mongolia Autonomous Region was selected as a research case. The water chemistry and nitrate nitrogen contents of groundwater samples from the whole area during the entire crop growing period （in March, May, July and September） were analyzed. The temporal and spatial distribution characteristics of the samples taken from 27 groundwater wells in 2003 and 2008 were studied. In 2003 before summer irrigation, the area with the nitrate nitrogen concentration of groundwater larger than 10 mg/L for the Jiefangzha irrigation area accounted for 9.95 % of the total irrigation one, and that with the annual average nitrate nitrogen concentration higher than 10mg/L accounted for 9.02% of the total irrigation one. In March of 2008, the area with the nitrate nitrogen concentration of groundwater larger than 10 mg/L was 5.22% of the total irrigation one, and that with the annual average nitrate nitrogen concentration higher than 10mg/L was 5.20% of the total irrigation one. The monitoring results and temporal and spatial distribution trend from 2003 to 2008 indicate that there is severe nitrogen pollution of the groundwater in the study area, however, the implementation of water-saving irrigation projects and measures has positive roles in reducing the loss of fertilizer leaching and the pollution of groundwater. Especially the reduction of autumn irrigation amount and the decrease of groundwater level both have remarkable function in the reduction of nitrate nitrogen leaching and pollution of groundwater.