Study On Characteristics Of Mercury Accumulation And Adsorption In Soil Around Coal Mining Areas Of Inner Mongolia

The investigation in Xilin Gol League of Inner Mongolia showed that the mercury content in soil near coal-fired power plants was higher than soil far from the coal-fired power plants and higher than the upper limit of local background value,which indicated the soil around the coal-fired power plants had been contaminated by mercury from coal-fired flue gas.Therefore,the research on mercury migration behavior in soil of this area may be of some scientific significance for the study of possible mercury pollution.Mercury adsorption-desorption in sand of Inner Mongolia grassland was explored through batch equilibrium methods with orthogonal experiments,including the effect of soil/solution ratio,initial mercury concentration,pH,humic acid content and NaNO₃concentration on mercuric chloride adsorption-desorption,as well as the effect of soil/solution ratio,initial methyl mercury concentration,pH,particle size distribution of soil and sterilization on methyl mercury adsorption-desorption.It was discovered by fitting experimental data that the adsorption behavior of mercury in grassland sand was in accordance with pseudo-second-order kinetic model and Langmuir adsorption isotherm model,which means the adsorption is mainly chemical process and irreversible.The results of mercuric chloride adsorption in sand show that:?1?The more the soil/solution ratio is,the slower the adsorption rate is,the stronger the adsorption ability is,and the higher the desorption rate is,but the absolute desorption is light.?2?The adsorption capacity of soil increases with a growing number of initial mercury concentration.?3?Adsorption capacity reaches maximum when pH is 7.5.No matter higher or lower than 7.5,the adsorption capacity reduces.And the bigger the gap is,the higher the reduction degree is.?4?Adsorption capacity reaches maximum when humic acid content is 0.6mg/g.No matter higher or lower than 0.6mg/g,the adsorption capacity reduces.And the bigger the gap is,the higher the reduction degree is.Meanwhile,adsorption capacity reaches the second maximum when humic acid content is 0mg/g.?5?When NaNO₃ concentration is in the range of 0.08⁸0mg/L,adsorption capacity is largest at 0.08mg/L NaNO₃ and smallest at 80mg/L NaNO₃.?6?The factors that affect the adsorption behavior of mercuric chloride in sand from the primary to the secondary order is as follow:initial mercury concentration>soil/solution ratio>pH>NaNO₃concentration>humic acid content.The results of methyl mercury adsorption in sand show that:?1?The adsorption capacity of soil decreases with fewer and fewer soil/solution ratio.?2?The more the initial methyl mercury concentration is,the stronger the adsorption capacity is,the faster the reaction rate is,and the less the desorption rate is.?3?Adsorption capacity and desorption rate reach the largest when pH is 7.Strong acid and strong alkali environment are not conducive to adsorption of methyl mercury in sand.And adsorption capacity and desorption rate reach the lowest under the strong alkali circumstance.?4?Adsorption capacity and reaction rate increase after sterilization.?5?The factors that affect the adsorption behavior of methyl mercury in sand from the primary to the secondary order is as follow:initial methyl mercury concentration>soil/solution ratio>pH>soil treatment.