青海省德令哈盆地第四系地下水质量评价

The Quaternary Groundwater Quality Evaluation of Delingha Basin in Qinghai Province

地下水质量评价是保护和合理开发利用地下水资源的前提。为准确反映德令哈盆地地下水质量状况,以青海省德令哈盆地第四系地下水的66组水质测试数据为基础,选取12项一般化学指标和4项毒理学指标共16项评价指标,采用基于最差指标判别法和改进的内梅罗指数法相结合的分类组合评价方法对地下水质量进行评价。结果表明:①德令哈盆地第四系地下水质量整体较好。其中,Ⅰ—Ⅲ类地下水采样点数占总采样点数的74.24%,Ⅳ类地下水采样点数占10.61%,Ⅴ类地下水采样点数占15.15%。②德令哈盆地内承压(自流)水质量优于潜水,冲湖积平原区地下水质量优于其他地区。③参评的16项指标中超标率(超Ⅲ类水)大于10%的指标有5种,由高到低依次为硫酸盐、总硬度、钠、溶解性总固体和氯化物。造成本区地下水质量超标的主要因素是地下水中的一般化学指标,三氮和毒理学指标超标较少。④本区地下水质量受原始地质环境和自然环境的控制,受人类活动影响较小。特定的地形地貌、地质构造和沉积环境控制着含水岩组的形成和地下水的循环演化,从而控制着地下水的整体质量;而干旱少雨的气候影响着浅层地下水的质量。

Groundwater quality evaluation is the premise of the protecting and rationally exploiting of groundwater resources.In order to accurately reflect the groundwater quality in Delingha basin,12 general chemical indexes and 4 toxicological indexes were selected using a combination evaluation method of worst index judgment method and improved Nemerow index method,which was based on 66 groups of Quaternary groundwater quality test data in Delingha basin,Qinghai Province.The results show that:①the overall quality of Quaternary groundwater in Delingha basin is good.Samples from grade Ⅰ-Ⅲgroundwater accounts for 74.24%of the total,and grade Ⅳ accounts for 10.61%,grade Ⅴ for 15.15%.②The quality of confined(artesian)water in Delingha basin is better than that of phreatic water,and the groundwater quality in the alluvial lacustrine plain areas is better than that in other areas.③Among the 16 indexes evaluated,5 indexes,which are sulfate,total hardness,natrium,TDS and chloride,exceed the standard level and the rate of excess is greater than 10%.The major transnormal items are the general chemical indexes in the groundwater,while the 3-nitrogen and toxicological indexes are less exceeding.④The quality of groundwater in this area is more controlled by the original geological and natural environment and less affected by human activities.The specific landform,geological structure and sedimentary environment controlled the formation of aquifer and the cyclic evolution of groundwater,thereby controlling the overall quality of groundwater,while the arid and rainless climate affects the quality of shallow groundwater.