岩溶地下水有机污染特征分析——以贵阳市某加油站为例

Analysis of Organic Pollution Characteristics of Karst Groundwater: A Case Study of a Gas Station in Guiyang

许多有机化合物对人体和生物有毒害作用,其中一些具有"三致作用"。地下水有机污染研究开始于20世纪60—70年代,经过半个世纪的发展,国际上已把地下水污染研究的重点从无机污染物转向有机污染物。在岩溶发育地区,地质环境脆弱,防污能力差,地下水具有易污染性,有机污染物在岩溶地区的分布有别于其他地区。本文以贵阳市某加油站15年前发生的油灌泄漏污染事件为例,通过地面调查、地质雷达、钻探、样品分析和综合研究等方法查明了地下有机污染物的运移规律、分布范围以及地下有机污染物的组分特征。经分析对比1999年、2007年以及2012年的研究成果,结果表明:(1)受岩溶发育形态的影响,场地内有机污染物在地下具有富集与稀释的双重特性;(2)在岩溶管道发育、地下水水头高度低于基岩面的地带,有机污染物组分含量总体呈减少的趋势;(3)在以溶蚀裂隙为主、地下水水头高度高于基岩面的地带,有机污染物不断富集,年扩散速率仅为12 m。

Many organic compounds are toxic to humans and living things, and some of them have a“three-induction effects”. Groundwater organic pollution studies began in the 1960s and 1970s. After half a century’s development, the international groundwater contamination study has turned its focus from inorganic contaminants to organic contaminants. The geological environment is fragile and the antifouling capability is poor in karst regions, where the organic pollutant distribution and migration are different from things of other regions. Exemplified by the case of the leakage of the tank at a gas station in Guiyang 15 years ago, the authors investigated the migration regularity of the underground organic pollutants, the pollution distribution and the characteristics of the organic pollutants by means of field survey, GPR, drilling and sample analysis. Through a comparative study of the results obtained in 1999, 2007 and 2012, the authors have reached some conclusions：（1） The organic pollutants have dual characteristics of enrichment and dilution in the underground affected by the karst morphology; （2） In the area where karst channel is developed and the groundwater level is lower than the bedrock surface, the underground organic pollutants content tends to decrease generally;（3） In the area where the fissures are dominant and the groundwater level is above the bedrock surface, the organic pollutants are accumulated and diffused downward slowly, and the diffusion rate can reach 12 m per year.