The Effect Of Biochar On The Migration Of Mercury And The Change Of Various Forms Of Mercury Content In Soil

The effect of biochar on the migration of mercury and the change of various forms of mercury content in sandy soil is studied by this reserch.Field experiments is carried out on sandy soil in Zhanggutai.HgCl₂ was taken as exogenous mercury to simulate atmospheric deposition,and biochar with different concentration gradients?0?0.5?1.0?2.0?4.0?8.0?16.0g/kg?was added to soil contaminated by simulated mercury.Different forms of mercury in soil samples were extracted by Tessier continuous extraction method,and mercury content in soil and plants was determined by atomic fluorescence photometer.To explore the changing trend of mercury and mercury speciation in soil and plant under the influence of biochar,the effects of biochar on mercury content and mercury speciation in soil were studied emphatically,and the changing regularity of mercury in soil-plant system and the characteristics of mercury speciation transformation in soil were revealed.It is helpful to seek effective control of environmental behavior of mercury in soil and to seek biological control of mercury in soil.It was found that biochar could effectively change soil physical and chemical properties,increase soil pH value and organic matter content,and reduce soil bulk density.With the increase of the proportion of biochar in soil,the total mercury content in soil increased significantly,and the mercury content in plant decreased accordingly.The biochar can fix the mercury in soil,thus reducing its bioavailability,making plants absorb less mercury and reducing soil toxicity.In mercury-contaminated soils,mercury mainly occurs in the form of organic matter bound and residue,while other forms of mercury account for a relatively small proportion.When biochar is applied,biochar is beneficial to passivating mercury in soil and transforming it into inert form which is not easily absorbed by plants.The water-soluble,exchangeable and iron-manganese oxide bound states decrease with the increase of biochar addition,while the content of carbonate bound state,organic matter bound state and residue state increased.The results showed that biochar had a significant effect on mercury content and mercury form in soil and plant.