寻找人类活动影响南明河的水化学指纹:Ⅰ.空间变化

Searching for Hydrochemical Imprints Indicating Human Impacts on the Nanming River: Ⅰ.Spatial Variations

城镇化和城市化通常是在河流流域内向前推进的,这导致人类活动对河流的污染越来越严重。防治这类河流污染的主要措施是截污沟修建以实现污水、雨水分离。那么截污沟修建后的效能如何?截污沟修建后中心城区水质如何变化?是否真的好转?为了回答这个问题,我们于2008年10月、2009年1月、4月、7月对贵阳市南明河主城区河段的8个断面进行了4次采样,获得了水温(T)、pH、电导(EC)、溶解氧(DO)、主要阳离子(K+、Na+、Ca2+、Mg2+)和主要阴离子(Cl-、NO3-、SO24-、HCO3-)含量的空间变化情况。相对于城区边缘,主城区河段主要离子含量和电导显著性升高,这种升高不是支流汇入的结果,而是人类活动导致。这说明了3种可能性:截污沟收集废水的不完全性、截污沟渗漏的可能性和非点源污染源存在的可能性。水化学分析提供了简单易行的评估截污沟效能的方法。

Rivers flowing through cities have been increasingly contaminated due to the discharges of sewage water contributed by domestic, commercial and industrial activities. Construction of interception sewers is a major measure to separate rain water from waste water. In order to evaluate the efficiency of sewage interception, we collected water samples across eight sections in the downtown part of the Nanming River in Guiyang in October, 2008, and January, April and July, 2009. These samples were analyzed for major ions （K＋ , Na＋ , Ca2＋ , Mg2＋ , C1- , NO3- ductivity （EC） and dissolved oxygen （DO） were determined in site. , SO42- , HCO3- ） while temperature （T）, pH, electric con- EC and major ions showed significant increases. These in- creases cannot be attributed to the confluence of tributaries, but to human activities. That implies three possibilities： incom- pleteness of sewage interception, leakage of interception sewers and existence of some non-point polIution sources. This work indicates that hydrochemical analysis may be a simple method to evaluate the efficiency of interception projects.