Institute of Hydrogeology and Environmental Geology, Chinese Academy of Geological Sciences, Shijiazhuang, China; Hebei Key Laboratory of Groundwater Remediation, Shijiazhuang, China.
Institute of Hydrogeology and Environmental Geology, Chinese Academy of Geological Sciences, Shijiazhuang, China.
J Contam Hydrol. 2023 Mar;254:104130. doi: 10.1016/j.jconhyd.2022.104130. Epub 2022 Dec 31.
Aluminium(Al)-rich (> 0.2 mg/L) groundwater has received more concerns because of its harmful to human beings. Origins of large-scale occurrence on Al-rich groundwater in urbanized areas such as the Pearl River Delta (PRD) are still little known. The current work was conducted to investigate spatial distribution of Al-rich groundwater in the PRD, and to discuss its origins in various aquifers. For that, 265 groundwater samples and 15 river water samples were collected, and 21 hydrochemical parameters including Al were analyzed by using conventional analytical procedures. The results showed that groundwater Al concentrations were up to 22.64 mg/L, and Al-rich groundwater occurred in 15% of the area occupied by the PRD. Al-rich groundwater in the coastal-alluvial aquifer was about 2 times those in alluvial-proluvial and fissured aquifers, whereas the karst aquifer was absent. In the coastal-alluvial aquifer, Al-rich groundwater in the peri-urban area was 2 or more times those in urbanized and agricultural areas, whereas the remaining area was absent. By contrast, in the alluvial-proluvial aquifer, Al-rich groundwater in the remaining area was 1.5-3.5 times that in other areas; in the fissured aquifer, the distribution of Al-rich groundwater was independent of land-use types. The infiltration of wastewater from township enterprises was main anthropogenic source for Al-rich groundwater in urbanized and peri-urban areas, whereas irrigation of Al-rich river water was the main one in the agricultural area. Naturally dissolution of Al-rich minerals in soils/rocks, triggered by both of pH decrease resulted from nitrification of contaminated ammonium (e.g., sewage leakage, the use of nitrogen fertilizer) and acid deposition, was the main geogenic source for Al-rich groundwater in the PRD. The contribution of anthropogenic sources to Al-rich groundwater in the coastal-alluvial aquifer was more than that in alluvial-proluvial and fissured aquifers, whereas the contribution of geogenic sources was opposite. In conclusion, the discharge of township enterprises wastewater and ammonium-rich sewage, the emission of nitrogen-containing gas, and the use of nitrogen fertilizer should be preferentially limited to decrease the occurrence of Al-rich groundwater in urbanized areas such as the PRD.
富含铝（Al）的地下水（浓度大于 0.2 毫克/升）因其对人类有害而受到更多关注。然而，在城市化地区（如珠江三角洲（PRD））大规模出现富含铝地下水的成因仍知之甚少。本研究旨在调查 PRD 地区富含铝地下水的空间分布，并探讨其在不同含水层中的成因。为此，采集了 265 个地下水样本和 15 个河水样本，采用常规分析方法测定了包括铝在内的 21 项水文地球化学参数。结果表明，地下水铝浓度高达 22.64 毫克/升，PRD 地区 15%的地区存在富含铝地下水。滨海冲积含水层中的铝含量是冲积-洪积含水层和裂隙含水层的 2 倍左右，而岩溶含水层中则不存在。在滨海冲积含水层中，城市周边地区的富含铝地下水是城市化和农业地区的 2 倍以上，而其余地区则不存在。相比之下，在冲积-洪积含水层中，其余地区的富含铝地下水是其他地区的 1.5-3.5 倍；在裂隙含水层中，富含铝地下水的分布与土地利用类型无关。乡镇企业废水的渗透是城市化和城市周边地区富含铝地下水的主要人为来源，而富含铝河水的灌溉则是农业地区的主要人为来源。受污染氨（例如污水泄漏、化肥使用）硝化导致的 pH 值下降和酸沉降触发的土壤/岩石中铝富矿的自然溶解，是 PRD 地区富含铝地下水的主要地球成因来源。人为来源对滨海冲积含水层中富含铝地下水的贡献大于冲积-洪积和裂隙含水层，而地球成因来源则相反。综上所述，应优先限制乡镇企业废水和富铵污水的排放、含氮气体的排放以及化肥的使用，以减少城市化地区（如 PRD）富含铝地下水的发生。
