Zheng Tao, Jiao Tuan-Li, Hu Bo, Gong Jian-Shi, Hou Xiang-Meng, Wang He-Sheng
Geological Survey of Anhui Province(Anhui Institude of Geological Sciences), Hefei 230001, China.
Nanjing Center, China Geological Survey, Nanjing 210016, China.
Huan Jing Ke Xue. 2021 Feb 8;42(2):766-775. doi: 10.13227/j.hjkx.202006037.
Groundwater is an important water source in the central Guohe River basin but pollution and water quality deterioration present a significant challenge. Here, 80 groups of groundwater samples were collected between June and September 2019 including 61 groups of shallow groundwater samples, 9 groups of middle groundwater samples, and 10 groups of deep groundwater samples. The hydrochemical characteristics and formation mechanisms of groundwater at these different depths were analyzed using statiatical techniques, Piper triangular diagrams, Gibbs figures, and ion ratios. The following results were noted:① Groundwater is weakly alkaline overall, and the dominant anion and cation at different depths were HCO and Na. The shallow and deep groundwater mainly consist of fresh water while the middle groundwater is mainly brackish water. The hydrochemical typology of the shallow groundwater was mainly HCO-Ca·Mg and HCO-Na·Mg. HCO·SO·Cl-Na was found to be the dominant hydrochemical typology in the middle and deep groundwater. ② The chemical composition of the groundwater shows notable vertical variations. With depth, the mean mass concentrations of TDS, Na, Mg, Cl, SO, and HCO first increase and then decreasing, while the mean mass concentration of Ca gradually decreases. These vertical differences are closely related to the sedimentary environment of the aquifer and the intensity of water-rock interaction. ③ The formation of groundwater hydrochemical characteristics is influenced by water-rock interactions, cation exchange, and human activities, with water-rock interaction dominated by sodium silicate dissolution. Human activities generally have the greatest impact on the shallow groundwater. ④ The water quality of the deep groundwater is notably better than that of the shallow and middle groundwater. However, excessive exploitation of the deep groundwater resource has led to the formation of a regional groundwater funnel, enhancing the difference in middle and deep groundwater levels. To reduce the risk of ground subsidence and the contamination of the deep water with middle brackish water, deep groundwater exploitation wells should be carefully positioned and regulated.
地下水是郭河中游流域的重要水源，但污染和水质恶化带来了重大挑战。本文于2019年6月至9月采集了80组地下水样本，其中包括61组浅层地下水样本、9组中层地下水样本和10组深层地下水样本。运用统计技术、派珀三线图、吉布斯图和离子比率等方法，分析了不同深度地下水的水化学特征及其形成机制。结果表明：① 总体而言，地下水呈弱碱性，不同深度的主要阴离子和阳离子分别为HCO₃⁻和Na⁺。浅层和深层地下水主要为淡水，而中层地下水主要为微咸水。浅层地下水的水化学类型主要为HCO₃-Ca·Mg和HCO₃-Na·Mg。HCO₃·SO₄·Cl-Na是中层和深层地下水的主要水化学类型。② 地下水的化学成分呈现出显著的垂直变化。随着深度增加，TDS、Na、Mg、Cl、SO₄²⁻和HCO₃⁻的平均质量浓度先升高后降低，而Ca的平均质量浓度逐渐降低。这些垂直差异与含水层的沉积环境和水岩相互作用强度密切相关。③ 地下水水化学特征的形成受水岩相互作用、阳离子交换和人类活动的影响，其中水岩相互作用以硅酸钠溶解为主。人类活动对浅层地下水的影响通常最大。④ 深层地下水水质明显优于浅层和中层地下水。然而，深层地下水资源的过度开采导致了区域地下水漏斗的形成，加剧了中层和深层地下水位的差异。为降低地面沉降风险以及防止中层微咸水对深层水的污染，应谨慎定位和规范深层地下水开采井。
