人类活动影响下的垂直气候带岩溶泉地球化学特征对比:以重庆金佛山水房泉、碧潭泉为例

Comparison of the Geochemical Characteristics of Karst Springs of a Vertically Zoned Climate Region under Human Activity:A Case of Shuifang Spring and Bitan Spring in the Jinfo Mountain Area,Chongqing

为探讨人类活动影响下的垂直气候带岩溶泉水化学变化,以重庆金佛山水房泉和碧潭泉为例,基于两泉自然环境和人类活动强度差异,利用独立样本t检验、Gibbs图解法、主成分分析(PCA)及地球化学敏感性分析等方法,对两泉水文地球化学特征及其控制因素进行对比研究.结果表明,垂直气候带岩溶发育的差异性导致碧潭泉离子总浓度高于水房泉.不同高程的岩性决定了水房泉水化学类型为HCO3-Ca型,而碧潭泉为HCO3-Ca·Mg型.碳酸盐岩溶蚀是两泉Ca2+、Mg2+和HCO3-的主要来源,水房泉SO42-、NO3-、PO43-、K+和Na+在冬夏季受酒店排污影响出现峰值,碧潭泉各指标年内变化平稳.水房泉水属于Ⅳ类水,而碧潭泉水质相对较好. PCA分析表明水-岩作用为两泉的首控因子,酒店排污和来自降水的离子输入分别对水房泉、碧潭泉水质具有重要影响,同时降水导致的水土流失与淋滤效应也对两泉有一定影响.水房泉的地球化学敏感性大于碧潭泉,故应针对不同高程岩溶系统特点制定相应保护措施,特别是要重视景区酒店污水的处理.

To investigate the hydrochemical variation of karstic groundwaters in a vertically zoned climate region affected by human activity,Shuifang Spring and Bitan Spring in the Jinfo Mountain area of Chongqing were selected as a study site. Based on the differences between the natural state and intensity of human activity of these two springs,their hydrogeochemical characteristics and the controlling factors on karstic groundwaters were analyzed by means of independent sample t tests,the Gibbs graphic method,principle component analysis( PCA),and geochemical susceptivity analysis. The results show that differences in karst development in the vertical climatic zone leads to higher total ion concentrations in Bitan Spring than in Shuifang Spring. The hydrochemical types of Shuifang Spring and Bitan Spring are HCO3-Ca and HCO3-Ca·Mg,respectively,which reflect the lithology of their different elevations.Carbonate rock dissolution is the main source of Ca2+,Mg2+,and HCO3-in karstic groundwaters. Hotel sewage discharge supplies SO42-,NO3-,PO43-,K+,and Na+in Shuifang Spring,which peaked in winter and summer,while hydrochemical parameters of Bitan Spring changed smoothly throughout the year. The water quality of Bitan Spring is better than Shuifang Spring( Shuifang Spring water is classified as Class Ⅳ). PCA shows that the water-rock interaction was the first controlling factor. Hotel sewage discharge and ions from precipitation had important effects on Shuifang Spring and Bitan Spring,respectively. In addition,the effects of soil erosion and leaching caused by precipitation also impact on the water quality of two springs to some extent. The geochemical susceptibility of Shuifang Spring was greater than that of Bitan Spring;therefore,corresponding measures should be formulated according to the characteristics of these differently elevated karst systems when exploiting groundwater resources. This is especially the case for the treatment of hotel sewage.