模拟污水对碳酸盐岩的溶蚀作用及其潜在的环境意义

Corrosion of Carbonate Rock by Artificial Drainage and its Potential Effects to Environment

碳酸盐岩是个巨大的碳源和钙源,在地球表面分布极广。随着近年来污水排放量的增加,对地表碳酸盐岩的溶蚀产生重大影响。为研究污水对碳酸盐岩的溶蚀作用及其环境效应,利用原子吸收分光光度计、pH计、酸滴定法、扫描电子显微镜-能量扩散X射线谱仪和X-射线粉晶衍射等,分别测定反应体系中的金属离子浓度、pH值、HCO3-浓度、碳酸盐岩被溶蚀前后表面形态和组分变化等指标。研究发现,模拟污水(含有几种重金属离子、H2PO4-、NH4+、脲和土壤微生物等)对碳酸盐岩的溶蚀结果有显著差异,如模拟污水对碳酸盐岩有强烈的溶蚀作用,使其释放更多的Ca和C;低浓度Pb(NO3)2溶液对碳酸盐岩溶蚀表现为吸收CO2;高浓度的Pb(NO3)2、CuCl2、CuSO4和土壤微生物扩增溶液对碳酸盐岩溶蚀表现为释放CO2;重金属盐溶液和复合污水对碳酸盐岩溶蚀后有次生矿物生成等。

Carbonate rocks,huge sources of carbon and calcium,cover a large area of the earth surface.More and more drainage are drained by mining industry and domestic life development recently.In order to study carbonate corrosion by drainage and its effects to the natural environment,we determined cation concentrations,pH values,HCO-3 concentration and characteristics of rock surface and components induced by corrosion using atomic absorption spectrophotometer（AAS）,pH meter,alkalinity-titrimetric method,SEM-EDX and XRD.The results showed that the parameters induced by corrosion were significantly different between the test groups and the controls.For example,carbonate rocks corrosion was much more intensely caused by drainage,thus more Ca and C were released from the carbonate rocks.We found that CO2 was absobed when carbonate rocks were being corroded by solution of diluted heavy metal cations,but was released when the corrision solution contains high concentrations of Pb（NO3）2、CuCl2、CuSO4 and microbes.Additionally some epigenetic minerals were generated during carbonate rocks corrosion by complex drainage.We thought hydrochemical changes caused by the sewage and the principle of entropy increase could be used to interpret why drainage induces the carbonate rock intense corrosion.