典型表层岩溶泉水化学对暴雨响应特征研究--以广西马山弄拉兰电堂泉为例

Hydrochemical response of typical epikarst spring to rainfall: A case study of Landiantang Spring in Nongla,Mashan County in Guangxi Province

利用多参数自动记录仪对广西马山弄拉兰电堂泉的降雨量、水位、水温、pH值、电导率、K+、NO3-和Ca2+浓度进行了自动监测。结果发现,泉水在降雨期间pH值呈降低趋势的同时还伴随着电导率和Ca2+浓度的急剧降低。此外,利用WATSPAC软件计算泉水饱和指数(SIC、SID)和二氧化碳分压(logPCO2),发现暴雨期间的SIC、SID和logPCO2均比正常情况下的低。由此可以推断泉水的水化学动态规律是由雨水的稀释作用造成的。进一步分析K+和NO3-的动态变化(暴雨时K+和NO3-出现富集的异常现象),推断石山地区植被的生长受限可能不但与土壤中必需元素的有效背景值低有关,而且还与表层岩溶带具有较高的裂隙易造成大量有益元素流失有关。此外,农业活动中施用的化肥等也将随着降雨进入水体造成表层岩溶泉和地下河的污染并产生一系列的环境问题。

The rainfall, water level, water temperature, pH, conductivity, K^＋, NO3^- and Ca^2＋ of the Landiantang epikarst spring in Nongla, Mashan County in Guaugxi Province, were measured by a multi-parameter automatic data logger. It was learned that, during rainfall, conductivity and Ca^2＋ decreased rapidly along with a decrease in pH. WATSPAC calculations of the saturation index （SIC, SID） and CO2 partial pressure （LogPCO2） of the spring showed that the SIC, SID and LogPCO2 were lower during rainfall than at other times, which indicated that the dilution caused by precipitation controlled the hydrochemical variation of the spring. Based on the abnormal enrichment of K^＋ and NO3^-, it was concluded that restricted plant growth was probably caused not only by the low effective background value of liable dements in soil but also by the loss of these elements in the cracked epikarst zone. Moreover, fertilizers used in agriculture came into the water bodies with rainfall, which could cause contamination of epikarst springs and groundwater and other environmental problems.