The Migration Rules And Risk Assessment Of Fluorine In Water-Soil-Air-Plant In Shihezi,Xinjiang

Fluorine is commonly found in natural environment,which is one of the trace elements widely distributed in air,soil,water and plants.Excessive or insufficient fluorine intake from the environment can affect the human body.In recent years,Xinjiang has introduced a large number of enterprises and factories to develop its economy.Coal-burning and sewage pollution have seriously polluted the air,soil,water bodies,and plants.Therefore,it is urgent to carry out the study on the distribution characteristics and migration and transformation rules of fluorine in water soil air plant in the drought saline environment in Xinjiang.This paper take coal-fired power plant as the research object in Shihezi,Xinjiang,to study the distribution characteristics of fluorine in soil and water,the fluorine content of air and plants,and analyze the laws of migration and transformation and its influencing factors;study the adsorption and desorption characteristics of four types of soil on fluorine in Shihezi;combined with mathematical models to study the degree of fluorine pollution in the soil and ecological risk,reveal high-risk areas of fluorine pollution,provide the basis for the government to develop a fluorine pollution prevention and control policy.Below are key research findings:1.Accurate positioning using GPS,collected soil,water,plants and air samples in Shihezi,and analyzed the content and distribution characteristics of fluorine.Studies have shown that the form of fluorine present in soil is expressed by the mean size:Res-F>Ws-F>O.M.-F>Fe/Mn-F>Ex-F.The total fluorine content in the soil is higher in the northwest,north,and southeast of Shihezi and lower in the southwest.Fluorine content in surface water and most of groundwater in the study area is low,but it is higher in the groundwater in the northwest where the altitude is lower.The results show that the groundwater can be used for irrigation,but it cannot be used for drinking water.The fluorine content in the leaves exceeds the fluorine contamination index?1 mg/kg?in GB 2762-2005.2.The potted experiment was simulated by the results of fluorine content in air in Shihezi.Research shows that the concentration of air fluorine is between 0.03-3.37?g/m³ in one year in Shihezi.From October 2016 to March of the following year,the fluorine concentration in the air was higher,and it was lower in other months.Higher fluorine concentration affects the morphology of the plant.The fluorine content in the roots and leaves of pakchoi?B.chinensis?and leaf lettuce?L.sativa?initially increased and then gradually remained constant with increasing concentration of F sprayed,indicating that these two plant species are sensitive to fluorine.The F content in the roots and leaves of alfalfa?M.ruthenica?increased gradually;which indicated that this plant is tolerant to fluorine.Bioaccumulation factors and transfer factors of plants gradually decrease with the increase of available fluorine concentration.3.The fluorine adsorption and desorption characteristics of four types of soils were studied in Shihezi.The results showed that in the process of static isothermal adsorption and desorption,fluorine ions in the soil will be released into the solution when the initial fluorine concentration is low,that is,negative adsorption.With the increase of the initial concentration of fluorine,the amount of fluorine adsorbed in soil increased correspondingly,and the amount of desorption of fluorine in the soil also increased.The Langmuir equation,Freundlich equation,and linear adsorption equation were fitted to the four types of soil fluorine adsorption.From the fitting point of view,the Langmuir equation has the best results.With the increase of pH,the trend of fluorine adsorption is decreasing first and then stabilizing.4.Three different methods were used to evaluate the ecological risk of soil fluorine in Shihezi.The Nemero pollution index was 1.86,indicates that the soil is lightly contaminated and the fluorine emission should be reduced.This method may reduce the impact of some factors in the evaluation.The potential ecological risks were evaluated using the ER_tot,ER_bcc and ER_bff evaluation models,respectively.The order of their accuracy from large to small was ER_tot>ER_bf>ER_bc,indicating that the model ER_totot can better evaluate the ecological risk of soil fluorine in the region.the potential ecological risk index in the study area is between 0.21-4.29,the low level of risk in the southwest shows that the pollution level is low here,while the risk level in the northwest,northern and southeastern is medium to high,indicating that some of the soils in these areas are affected by the factories and have a high level of pollution.The remediation of soil fluorine pollution needs to be paid attention to.