基于"层级阶梯评价方法"的地下水质量与污染评价:以铜川市为例

掌握区域地下水质量及污染状况,对于地下水污染防治、地下水资源保护与管理具有重要作用,尤其是对西部内陆干旱区地下水资源尤为重要。本研究针对陕西铜川市地下水进行了系统采样,通过分析常规指标、无机毒理指标、微量有机指标,利用“层级阶梯评价方法”进行了地下水质量与污染评价。水质评价表明,2011年铜川市浅层水水质相对较差,可作为饮用水源或经适当处理后可做饮用水源的样品占样品总数的60%,不宜作为生活饮用水源的样品占40%。浅层水质量受天然背景和人类活动的共同影响,主要影响指标为总硬度、 {\mathrm{NO}}_3^{-}、TDS、Mg²⁺、 {\mathrm{SO}}_4^{2-};深层水水质相对较好,所有采样点均可作为饮用水源。深层水主要受天然背景影响,主要影响指标为Fe。污染评价表明,浅层水污染等级为1级、2级、3级、4级的样品分别占样品总数的44%、16%、32%、8%,污染主要分布在金锁关以南至川口以北的漆水河河谷地带;而深层水污染等级全部为1级,尚未受到人类污染影响。相比其他评价方法,层级阶梯评价法在区分天然背景和污染对地下水水质影响方面具有明显优势,结合区域背景分析和现场调查认识,能够成为科学掌握地下水水质及污染状况的有效手段。

Groundwater quality and pollution assessment based on ‘hierarchical ladder evaluation method’: A case study of Tongchuan Cit

Measurements of regional groundwater quality and pollution status play an important role in groundwater pollution control, groundwater resources protection and management, especially in the western inland arid areas. In this study, groundwater in Tongchuan City of Shanxi Province was systematically sampled and the groundwater quality and pollution status were evaluated through analyses of conventional, inorganic toxicological and trace organics indicators using ‘hierarchical ladder evaluation method’. The results showed that the shallow water quality in Tongchuan City was relatively poor in 2011, with 60% of the samples qualified as drinkable water or drinkable water after proper treatment and 40% as not suitable for drinking. The quality of shallow water was affected by both natural background and human activities, and the main influencing indicators were total hardness and {\mathrm{NO}}_3^{-}, TDS, Mg²⁺and {\mathrm{SO}}_4^{2-} contents. In contrast, the quality of deep water was relatively good, and all sampling sites could be used as drinking water sources. The deep water was mainly affected by natural background, and the main influencing indicator was total Fe. In terms of pollution grade, the shallow water samples with pollution grades 1, 2, 3 and 4 accounted for 44%, 16%, 32% and 8% of the total samples, respectively, with pollution mainly distributed in the Qishui river valley from south of Jinshuoguan to north of Chuankou; whereas the deep water samples were all assigned pollution grade 1, i.e., unaffected by human pollution. Compared with other methods, ‘hierarchical ladder evaluation method’ has obvious advantages in distinguishing the impact of natural background versus pollution on groundwater quality. Combined with regional background analysis and field investigation, this approach can be an effective way to scientifically acquire a good knowledge of regional groundwater quality as well as pollution status.