【作者】 张海涛；

【导师】 洪梅；

【作者基本信息】 吉林大学 ， 环境工程， 2015， 硕士

【摘要】 随着农业现代化的推进，耕地使用的氮肥日益增多，而作物所吸收的氮是有限的，大量的氮素将残留在土壤中，提高了地下水被污染的可能性。我国淡水资源相对短缺，地下水资源在工农业生产和居民生活用水里占有很大的比重，地下水资源保护显得尤为重要。所以有必要对农田氮素污染地下水风险进行合理评价，根据评价结果指导地下水资源的合理开发利用，以实现地下水资源的可持续利用。本文在阅读大量相关文献和统计资料的基础上，根据研究区基础资料的丰富程度以及风险指数的不同计算方法，分别提出了迭置指数方法、数值模型方法和解析模型方法对氮素污染地下水风险进行评价，并在吉林省中部地区对三种方法进行了实例应用，主要研究结果如下：（1）建立了迭置指数模型进行基础资料缺乏地区地下水污染风险评价，风险指数计算为各项指标评分和权重乘积的叠加：深入的分析了影响农田地下水污染风险的自然因素和农业因素，选取了11个评价指标构成指标体系，对各项指标的评价标准及权重进行了分配，建立了风险指数评价模型，最后应用ARCGIS技术将评价结果转化为污染风险分布图。在吉林省中部地区进行了实例应用，评价结果如下：研究区硝态氮污染地下水的风险分布不均，呈现东部高于西部，北方高于南方的特点；风险较高的地区在长春市境内，在德惠市和榆树市交界处出现了最高分区，风险最低的地区在公主岭市；（2）根据传递函数原理建立解析模型进行基础资料缺乏地区地下水污染风险评价，应用溶质迁移时间的概率密度函数来描述溶质在土壤中的迁移转化特征，并以模型计算得到的硝态氮的淋失量为标准划分地下水污染风险等级。应用解析方法模拟了典型黑土种植区农业生产过程，评价了研究区地下水污染风险，结果显示：硝态氮淋失量为12kg N/hm2，研究区地下水污染风险达到了Ⅰ级。（3）借助hydrus软件建立数值模型进行基础资料丰富地区地下水污染风险评价，风险指数以模型输出的硝态氮淋失量进行表征。模拟了吉林省中部五种典型种植区的实际气候条件、水文地质条件、农业活动、以及作物生长，应用数值方法展开了地下水污染风险评价，研究结果表明：铵态氮在土壤剖面的累积量白浆土种植区最多，冲积土种植区最少，硝态氮的累积量冲积土种植区最多，草甸土种植区最少；硝态氮的迁移速度明显比铵态氮高，所有土壤均在三年内完成穿透；硝态氮年平均淋失量分别如下：1.53、33.7、13.5、3.2和1.2kg N/hm2，即冲积土种植区硝态氮污染地下水风险达到了Ⅱ级，其他土壤种植区地下水污染风险均处于Ⅰ级。更多还原

【Abstract】 With the development of agricultural modernization, the use of Nitrogen fertilizeris on the rise, but the nitrogen of crop uptake is a fixed value, so a large amount ofnitrogen will remain in the soil that increases the possibility of groundwatercontamination. China is seriously deficient in fresh water resources, in many placesthe water for production of industry and agriculture and for people’s life depends ongroundwater, thus groundwater protection is of great importance. It is necessary toevaluate the risks of groundwater nitrate pollution, according to the evaluation result,guide the suitable development and use of groundwater resources, in order to ensurethe sustainable development and utilization of groundwater resources.On the base of a large number of relevant papers and literature, this paperproposes three means that overlay and index methods, numerical mode means,analytical model means to evaluate the risks of groundwater nitrate pollution,according to the abundance of basic data in the researched region and differentmethods of risk index computing, and conducts three application studies of practicalcase in the middle of Jilin Province, main results for this study are as follows:(1) Overlay and index methods was established to evaluate the risks ofgroundwater nitrate pollution for area without abundant basic data, and risk index wascalculated by overlaying the product of weights times grades: selected11appraisaltargets and constructed an index system of overlay and index methods, on the basis ofdeeply analysis of natural factors and agricultural factors that influence the pollutionrisk of farmland groundwater, then made the scoring criteria and assigned the weightfor all indicators, and sat up the risk index evaluating model, finally translate theevaluation results into risk maps. The results of the application study of practical casein the middle of Jilin Province as follows: the risk of groundwater nitrate pollutionwas in imbalance with the characteristic that the east was higher than the west and thenorth was higher than the south; the region with higher risk appeared in Changchunand the highest located at the junction of Dehui and Yulin, as the region with thelowest risk appeared in Gongzhuling. (2) In view of transfer function, analytical model means was established toevaluate the risks of groundwater nitrate pollution for area without abundant basicdata, probability density function of solute travel time was used to describe thecharacteristics of nitrogen transport and transformation in soil, and risk index wasrefered to the amount of nitrogen leached into groundwater. The process of localagricultural production in typical black soil planting area was simulated withanalytical model means, the results show that the amount of nitrogen leached fromthe simulated soil was12kg N/hm2, the risk of groundwater nitrate pollution is at levelone.（3）With the software of hydrus, numerical mode means was established toevaluate the risks of groundwater nitrate pollution for area with abundant basic data,and risk index was divided by the amount of nitrogen leached into groundwater,which was calculated through the outputs of software. Five typical planting area wereselected in the middle of Jilin Province for evaluating groundwater pollution risk bythe numerical mode means, and local weather conditions, hydrological geologicalconditions, agricultural activity and crop growth was inputted into the software, theresearch result shows that: the largest number of ammonium nitrogen accumulated inthe Albic soil planting area, the least in the Alluvial soil planting area, as the largestand the least number of nitrate nitrogen accumulated in the Alluvial soil and Meadowsoil planting area; nitrate nitrogen transported more quickly than ammonium nitrogenand penetrated the entire soil layer in the third year in all planting area; the amount ofnitrogen leached from the simulated soil as follows:1.53、33.7、13.5、3.2和1.2kgN/hm2, that is, the risk of groundwater nitrate pollution is at level two for alluvial soilplanting areas, as other areas were at level one.更多还原