Bioavailability Of Different Forms Of Mercury In Soil

Mercury is a kind of toxic heavy metals. With industrialization, the mercury pollution has been produced which has a great influence and harm to human beings and nature. A large number of studies have found that the toxicity of mercury in the soil is not related to the total mercury in the soil, but it is mainly related to the form of mercury in the soil. When mercury enters into the soil environment, its form is not fixed. Migration and transformation can occur between each other. Based on this, the thesis mainly discusses the mechanism of the different forms of mercury accumulation characteristics in the soil, the long-term stable migration as well as the biological effectiveness.The study on adsorption by means of simulation of single mineral soil mercury accumulation experiment explores different forms for adsorption of mercury and determines the adsorption capacity and adsorption on mercury adsorption strength, etc.The soil from the site of Yuan Da Park was studied. The study explores the law of the simulation of the nature in the migration and transformation by adding the form of mercury ions into the soil with a cycle of 360 days. We explore the conversion relationship of different forms between each other using improved Tessier extraction method for the determination of Hg in soils of different forms. At the same time, the partial correlation analysis was used to explore the relevance of different forms to reveal the transformation pathway.A pot experiment was conducted to study the bioavailability of a single mineral mercury contaminated soil.The study shows that the order of the adsorption amount of mercury, the size of the adsorption strength and the persistence of the adsorption of the 4 kinds of soil minerals were Fe2O3> MnO2> kaolin> CaCO3. As soon as the ionic mercury enters the soil, it becomes easier to combine with the iron and the manganese minerals. On the contrary, carbonate morphology is not stable and the holding capacity is relatively low which makes it easier to be activated and transformed. The long-term stability of the soil Hg shows that the changes of the contents in the soil after the end of the cycle are as follows:organic bound Hg> residual state Hg> Fe Mn oxidized Hg> carbonate form Hg> ionic mercury. The partial correlation analysis of the data reveals that the ionic mercury has a strong correlation with the iron manganese oxidation state mercury, residual mercury and organic combined mercury. Ionic mercury and organic combined mercury have a very strong negative correlation which means the great relationship between the ionic mercury reduction and organic mercury increase. The analysis results of the pot experiment show that the iron and manganese oxidation state mercury transforms to other forms under the effect of the plant and then becomes easily absorbed by the plants. With the correlation analysis of different forms of soil and plant uptake of Hg, it shows that carbonate form in the plants and soil, iron and manganese oxidation state and ionic states have good correlation which suggests that the plants easily absorb the several forms.