The Analysis On Thermal Releasing Existing Formation Of Mercury In Soil Of Chengdu City

Humen beings are paying more and more attention to the mercury enviromental problem, as the mercury is widely used in most fields. Especially in the city ecology system which is frail, the mercury contents in the media such as atmosphere, water, soil is much high, even exceed the level which the life can bear and seriously affect the standerd of living. So the study on the moving, changing, releasing and different formations of mercury is attracting more and more people to study.The thesis is researching on the exposed-soil in Chengdu city, based on the researches on the distribution of the thermal releasing mercury under 800℃, researching on the releasing formations of different tempreture, and making the following conclusions:1) The content order of the thermal releasing mercury in Chengdu urban soil is as follows: the resident area＞the garden area＞the riverine area; the first circle road＞the first to second circle road＞the second to third circle road. The result taking the thermal releasing mercury way to analyse the content and contribution trend is similar to taking the chemical way, which can prove the applicability of this way.2) Under 100℃thermal releasing, the formation order is as follows: the residual＞the alkali soluble＞the nitric acid soluble＞the acid soluble, and water soluble is completely released. Between 150℃to 350℃, the order is: the residual＞the alkali soluble＞the nitric acid soluble, the acid soluble and water soluble are completely released. Between 350℃to 800℃, the formation order is: the alkali soluble＞the residual＞the nitric acid soluble, the acid soluble and water soluble are completely released.3) According to the analysis, the trend of different formation is: the water solution is completely released in 100℃; The acid soluble is completely released in 150℃; The content of alkali soluble is increasing first, then decreasing and increasing later; The content of residual is no changing in lower tempreture, and suddenly decreasing when tempreture is about 350℃, then keep banlance in 500℃. In lower tempreture(the normal tempreture to 150℃), the main releasing formation is residual and the main compounds are Hg(NO₃)₂ and organic mercury; In middle tempreture (250℃-350℃), the main releasing formation is alkali soluble and the main compounds are HgS and HgO and so on; In higher temperature the main releasing formation is residual and the main compounds are HgS and so on.4) The relativity of the thermal releasing mercury in 50℃is lower with that in 100℃and 800℃, the later two temperature is too similiar and take on obvious relativity.