Key Lab of Karst Georesources and Environment of Ministry of Education, Guizhou University, Guiyang 550025, China; College of Resources and Environmental Engineering, Guizhou University, Guiyang 550025, China.
Key Lab of Karst Georesources and Environment of Ministry of Education, Guizhou University, Guiyang 550025, China; College of Resources and Environmental Engineering, Guizhou University, Guiyang 550025, China.
J Contam Hydrol. 2024 May;264:104356. doi: 10.1016/j.jconhyd.2024.104356. Epub 2024 Apr 30.
Karst groundwater plays an irreplaceable role in the formation and development of urban areas, and land-use and land-cover change (LUCC) and the input of pollutants during the urbanization process would pose potential environmental risks to underground rivers. We analysed the relationship between urbanization processes and underground river hydrochemistry over nearly 35 years in Guiyang city, southwest of China, it was found that concentrations of various cations and anions, as well as total dissolved solids (TDS), gradually increased with the urbanization process, with significant fluctuations during the rapid urbanization periods. The Hydrochemical Facies Evolution Diagram (HFED) clearly showed the influence of urbanization on the hydrochemistry of the underground rivers. The ion ratios of γMg/γCa-γHCO, γNa/γCl, Ca/Mg-Ca or Mg/Σ cations, HCO/SO-HCO or SO/Σ anions revealed two distinct phases in the hydrochemical evolution of the underground river system, highly consistent with the urbanization process. Before the rapid urbanization, acid deposition and agricultural activities affected the hydrochemistry, with HCO-Ca·Mg and HCO·SO-Ca·Mg as the dominant types controlled by limestone and dolomite dissolution in water-rock interactions. As acid deposition diminished, the input of SO from urban sewage compensated for the reduced impact, but the increased impermeable surfaces reduced the infiltration of atmospheric precipitation, leading to a reduced dissolution of dolomite minerals in water-rock interactions, resulting in a decrease in Mg and a change in the hydrochemical type. The hydrochemical type evolved from a single HCO·SO-Ca·Mg type and HCO-Ca·Mg type to multiple types, such as HCO·Cl-Ca, HCO·SO-Ca, HCO-Ca, and HCO·SO-Ca·Mg, and was highly unstable. With changes in land use, the proportions of various cations and anions in the hydrochemistry changed, especially NH, NO, SO, Na, and Cl, which were more sensitive to human activities. This study indicated the impact of urbanization on the hydrochemistry of the underground river system, with the input of SO from human activities and the increase in paved surfaces due to urbanization collectively altering the hydrochemical types of the underground river system. The rapid response of karst underground river system hydrochemistry indicates a potential impact on groundwater system by urbanization that should not be ignored.
喀斯特地下水在城市的形成和发展中起着不可替代的作用，而城市化过程中的土地利用和土地覆被变化（LUCC）以及污染物的输入，可能会对地下河造成潜在的环境风险。我们分析了近 35 年来中国西南部贵阳市城市化进程与地下河水质之间的关系，发现各种阳离子和阴离子以及总溶解固体（TDS）的浓度随着城市化进程逐渐增加，在快速城市化期间有明显波动。水化学相演化图（HFED）清楚地显示了城市化对地下河水质的影响。地下河系统水化学演化的离子比γMg/γCa-γHCO、γNa/γCl、Ca/Mg-Ca 或 Mg/Σ阳离子、HCO/SO-HCO 或 SO/Σ阴离子揭示了两个截然不同的阶段，与城市化进程高度一致。在快速城市化之前，酸沉降和农业活动影响了水化学，HCO-Ca·Mg 和 HCO·SO-Ca·Mg 是主要类型，由水岩相互作用中石灰岩和白云岩的溶解控制。随着酸沉降的减少，城市污水中 SO 的输入弥补了减少的影响，但不透水表面的增加减少了大气降水的渗透，导致水岩相互作用中白云岩矿物的溶解减少，导致 Mg 减少和水化学类型的变化。水化学类型从单一的 HCO·SO-Ca·Mg 型和 HCO-Ca·Mg 型演变为多种类型，如 HCO·Cl-Ca、HCO·SO-Ca、HCO-Ca 和 HCO·SO-Ca·Mg，且高度不稳定。随着土地利用的变化，水化学中各种阳离子和阴离子的比例发生了变化，特别是 NH、NO、SO、Na 和 Cl，它们对人类活动更敏感。本研究表明，城市化对地下河系统水化学的影响是由于人类活动中 SO 的输入以及城市化导致的铺面增加，共同改变了地下河系统的水化学类型。喀斯特地下河系统水化学的快速响应表明，城市化对地下水系统可能产生潜在影响，不容忽视。
