粤北某离子吸附型稀土矿地下水丰枯水期变化及污染评价

目的]探究离子型稀土矿区地下水的污染状况及其在时空尺度下的变化特点，为区域地下水污染防控及居民健康生活的保障工作提供科学依据。方法]以粤北某离子吸附型稀土矿及其周边为研究区，分别在丰、枯水期采集该区域地下水样品各10组，在检测水样6种常规指标和7种重金属指标的基础上，运用多元统计的方法和修正内梅罗综合污染指数法对地下水的污染现状进行分析与评价。结果]地下水超标组分包括硫酸盐(10%)、硝酸盐氮(30%)、氨氮(35%)、氟化物(40%)、硫化物(40%)、Mn(55.5%)、Pb(20%)和Cd(10%),其中氨氮和Mn污染程度明显更严重，超标组分中仅硫化物和氟化物浓度具有明显的时期特征，均表现为：丰水期>枯水期。地下水受污染极不均匀且整体污染程度非常严重，丰水期地下水水质较枯水期更差，污染在样点DXS₀₄,DXS₀₆和DXS₀₇所在位置有较大程度的集中。结论]各污染指标均与稀土矿使用的化学药剂存在运移转换关系，研究区地下水受稀土矿开采影响已不宜作为生活饮用水源。

Change and Pollution Evaluation of Groundwater from Wet and Dry Periods of Ion-adsorbed Rare Earth Mine in Northern Guangdong Province

Objective] The pollution status of groundwater in ion-type rare earth mining areas and its changes on the temporal and spatial scales were explored in order to provide a scientific basis for the prevention and control of regional groundwater pollution, and to guarantee a healthy life for residents. Methods] Ten sets of groundwater samples were collected from an ion-adsorbed rare earth mine in Northern Guangdong Province during both the wet season and the dry season. Based on the detection of six conventional indicators and seven heavy metal indicators in water samples, the current groundwater pollution status was analyzed and evaluated by using multivariate statistical methods and the revised Nemerow comprehensive pollution index method. Results] Groundwater exceeding standard components included sulfate (10%), nitrate nitrogen (30%), ammonia nitrogen (35%), fluoride (40%), sulfide (40%), Mn (55.5%), Pb (20%), and Cd (10%). The degree of pollution due to excessive ammonia nitrogen and Mn were significantly more serious. Only the concentrations of sulfide and fluoride in the over-standard components had obvious period characteristics, and they were both characterized by being greater during the wet season than during the dry season. Groundwater pollution was very uneven, and the overall pollution level was very severe. Groundwater quality in the wet season was worse than in the dry season, and pollution was concentrated to a greater extent at sample points DXS₀₄, DXS₀₆, and DXS₀₇. Conclusion] All pollution indicators had a migration and conversion relationship with chemicals used in rare earth mines. Groundwater affected by rare earth mines in the study area was no longer suitable as a source of drinking water.