基于GMS模拟预测硫酸储罐泄漏对地下水环境的污染——以南宁某饲料添加剂厂为例

Simulation and prediction of groundwater pollution from sulphuric acid tank leakage based on GMS model: a case from a feed-additive project in Nanning

硫酸储罐泄漏事故虽然很罕见,但由于罐中所含的SO2-4的浓度极高,一旦发生泄漏就会对地下水环境造成严重污染。为预测这种污染的严重程度,以南宁某饲料添加剂厂为例,利用水文地质测绘、钻探及地下水位监测获得该项目所在地的水文地质单元范围及其水文地质环境条件,通过钻孔注水试验测定出各含水层的渗透系数,再运用GMS进行数值模拟得到地下水等水位线图及地下水污染晕运移预测结果图。结果表明:硫酸储罐泄漏10000d后,含水层中SO2-4污染晕中心点的浓度仍高达788050mg/L(已降至原浓度的44.6%)。另外,由于项目所在地的地层透水性差,污染物的迁移非常缓慢,污染晕的净化作用主要靠含水层缓慢的稀释作用得以实现,所以含水层得到完全净化的时间将十分漫长。

The concentration of SO 2- 4 in the sulfuric acid tank is extremely high. Though there is few leakage of sulphuric acid tank, under abnormal conditions (i.e.sudden leakage of sulphuric acid), it may cause serious inorganic pollution to the underground aquifer. In order to predict the degree of groundwater pollution,the case of a feed additive project in Nanning city is illustrated. After hydrogeological surveying and mapping, drilling, and groundwater level monitoring, the scope of the hydrogeological unit and the regional hydrogeological condition were found out. The permeability coefficients of the aquifers were also obtained by borehole water injection tests, and a GMS software was used in numerical simulation to get the groundwater map and groundwater pollution halo of the study area. The prediction shows that the concentration at the central point of SO 2- 4 pollution halo is still as high as 788 050 mg/L after 10 000 days of the leakage accident(reduced to 44.6% of the original concentration).Because of low permeability of the formations, the migration of pollutants is slow. The decontamination effect of a polluted halo mainly depends on the slow dilution of the aquifer. There is a long way to go for us to purify the pollutants in groundwater completely.