Study On The Chemical Stabilization Of Mercury Contaminated Soils In Gold Mine Zone

With the study of correlation between various forms of heavy metals and plant absorption, people find out that the toxicity of mercury is not only related to the total amount, but also the distribution features. Traditionally, researchers usually determine which forms of mercury are biological effective by stepwise regression analysis or simple correlation analysis. However, the soil is a complex system, and each form of mercury is not exist independently, those processes, such as adsorption, desorption, transformation, are happened all the time, which makes the content of different forms variable.This study chose a gold mine zone contaminated of mercury in Fujian Quanzhou as the research object. The modified sequential extraction and partial correlation and regression analysis are used to analyze the total content of Hg, the bioavailability and its distribution, the forms in the soil of a Gold Mine sampling points. And then we put forward control measures of chemical stabilization and repair evaluation standard in this area. We determine parameters of chemical fixative NTSH in laboratory test, after that we promote pilot tests in the field, in order to determine the evaluation of stabilization of NTSH.The study indicate that, the mercury of organic combination state is the most important forms about more than 60%, in this soil. Generally speaking, it goes:organic bounds> residuals> the exchangeable> Fe-Mn oxides> carbonates. It also shows that the various forms of mercury do not exist independently in soil, but be in a state of dynamic balance by competition, migration and transformation. What’s more, it also shows that the forms of exchangeable and the organic are the effective state, which is easy to be taken up by plants, while others are not obvious; The curing agent NTSH can effectively reduce the content of effective state of mercury in soil, restrain the migration to the plant body from soil. And also, we find out that:the larger NTSH addition, the longer the curing time, the better evaluation of stabilization, in the case of no effect to plant growth. The curing rate can reach 80% by adding 0.36% NTSH, two months stabilization, by the single factor analysis. And the evaluation of stabilization with NTSH has a certain tolerance and it changes little with different pH, organic matter, temperature. The field pilot test is similar to the result in laboratory:the cure rate of effective mercury can reach 75%, and it can reduce near 80% mercury levels in plant. And the longer time stabilization, the better. So NTSH can be used to repair the mercury contaminated soil.