微生物与化学示踪岩溶地下水补给源和途径

Using chemical and microbiological indicators to track the recharge of underground rivers in a karst valley

在重庆岩溶地下河系统,进行两次高分辨率示踪试验,分析地下含水介质的类型;以硝化、反硝化细菌作为微生物指示因子,根据Cl-和流量聚类分析划分雨、旱季,分析其与NO2-、NO3-的相关性,判断地下水补给途径。两次示踪试验中示踪曲线均为单峰型,无拖尾,示踪剂回收率分别为93.94%、27%,最大视流速与平均视流速之比为1.26、1.12,说明该岩溶槽谷区存在大型的岩溶管道含水介质,水流畅通,无大型溶潭或岔道。聚类分析结果为：旱季（10月~次年4月）地下河出口S2处硝化细菌与NO3-、反硝化细菌与NO2-相关系数达0.9290、.811,与土壤渗透水性质类似;雨季（5~9月）时,微生物与NO2-、NO3-无相关性,R均低于0.5,与上游落水洞D1处地表水类似。说明旱季时地下水主要是地表下渗的裂隙水补给,流经与暗河连接的岩溶裂隙途径,雨季时为经落水洞流入地下河的地表径流补给岩溶管道。

Chemical and microbiological indicators were used to explore the conduits of underground water medium and the recharge of underground water in a typical karst valley in Chongqing, China. High resolution tracer tests of two times with uranine have been conducted to find out the conduits of underground water medium and its recharge. Classification with C1- concentration and discharge of the water in different sampling sites were used to divide the rainy reason and dry season specifically. With the results of classification, the correlation coefficient of nitrobacteria, denitrifyimg bacteria, which were the microbe indicator and NO2^- , NO3^- in different season, were analyzed. Using the chemical indicator tracking curves, which had only one peak without any tale, the recycleration of uranine was calculated to be 93.94 % and 27 %, and the ration between the maximum apparent velocity and the average apparent velocity was 1.26 and 1.12. Therefore, chemical tracking implied that there was a big conduit underground river without big ribbon or byroad. Classification showed a rainy season lasting from May to September, the rest of the year was a dry season. In the dry season, at the output （site $2） of the underground river, the correlative coefficient of nitrobacteria and NO3^- was 0.929. The correlative coefficient of denitrifyimg bacteria and NO2^- was 0.811, but such relation has not been found in the rainy season when the correlative coefficients were 0. 153 and microbe and NO2^- , NO3^ - 0.311. On the other hand, at the income （D1） of underground rivers, the relation of has been found neither in the dry season nor in the rainy season. In a word, microbiological tracking implied the main recharge of the underground river in a dry season was the soil penetrative water through the fissures in karst, but in a rain season, the main recharge was surface water flow through swallow holes.