重庆岩溶地下河水文地球化学特征及环境意义

岩溶地下河系统是岩溶地区重要的地下水资源,重庆地区分布有岩溶地下河380条,是重庆市重要的地下水资源。为宏观掌握重庆地区岩溶地下河水化学特征,了解区域岩溶地下河水化学影响因素及分布规律,研究了重庆不同地区61条岩溶地下河水文地球化学特征。结果表明,重庆地区岩溶地下河的溶解组分主要来源于碳酸盐岩的溶解,水化学类型为Ca-HCO₃型或Ca(Mg)-HCO₃型,但部分地下河水化学受到人类活动影响变为Na+Ca-HCO₃型、Na+Ca-SO₄型、Na+Ca-Cl型或Ca-SO₄+HCO₃型,且农业活动或城市废水对地下河水化学的影响比工矿业活动普遍。地下河水温度随海拔升高而逐渐降低。在相同的地质背景下,地下河Ca2+、Mg2+、HCO₃-等离子由于受不同区域岩溶作用强度差异的影响呈现出明显的区域性,SO₄2-、NO₃-、Cl-等指标由于受不同区域人类活动强度和方式的影响也显示出明显的区域性。总体来看,岩溶地下河水质正在恶化。

Hydrogeochemistry and environmental meaning of Chongqing subterranean karst streams in China

The subterranean karst stream services as an important water source to the groundwater supply system in the karst areas.There are approxinately 380 subterranean karst streams that supply groundwater to the areas of Chongqing municipalities.The hydrogeochemistry is studied for 61 subterranean karst streams in Chongqing.The result shows that the solutes are mainly originated from the dissolution of carbonate rocks through the water-rock interaction process.The groundwater chemistry is found to be of Ca-HCO₃ type or Ca(Mg)-HCO₃ type.However,the Na+Ca-HCO₃、Na+Ca-SO₄、Na+Ca-Cl or Ca-SO₄+HCO₃ type water have been detected in some of subterranean karst streams due to the influence of human activities.The impacts of agriculture activities and city sewages on hydrogeochemistry are more common than that of industrial and mining activities.The groundwater temperature gradually decreases with the increase of elevations.For the same geological setting,the presence of Ca²⁺、Mg²⁺、HCO₃^- exhibitssignificant regionality due to the discrepancy of karst processes in different areas.The same regionality is also found in the distribution of K⁺、Na⁺、SO₄^2-、NO₃^-、Cl^- because of human activities.The study concludes that the hydrogeochemical condition of Chongqing karst subterranean streams is deteriorating due to the industrial and agricultural activities as well as the discharge from the city sewage system.