Preliminary Study On Enhanced Phytoremediation Of Hg Contaminated Farmland Soil

Mercury has become one of the most common and highly harmful heavy metal pollutants in the soil.it could transport and transform in environment through dissolution,sedimentation and so on.Due to food chain,Bioconcentration and biomagnification,Hg could cause harm to the ecological environment and human beings health.Currently,the main restoration of Hg in soil were physics,chemistry,microbial remediation and other projects.However,these methods had the disadvantages of small area removal,secondary pollution,and large environmental impact.The phytoremediation method was favored by people because of its unique advantages.Among them,the economic crops had large biomass,strong environmental adaptability and can bring economic benefits and became a research hotspot in the field of phytoremediation.In this study,ramie,Indian mustard,rapeseed and cotton four economic crops were selected for phytoremediation of Hg-contaminated soil in the field,and activators sodium thiosulfate and fulvic acid were used to induce phytoremediation of Hg-contaminated soil.Field experiments were conducted to study the effects of activator sodium thiosulfate and fulvic acid on the remediation of heavy metal Hg-contaminated soil by four plants,and the total Hg in soil was analyzed under different concentrations of sodium thiosulfate and fulvic acid.The changes of effective Hg were analyzed,and the changes of Hg content in various parts of four plants were analyzed in order to provide scientific basis for strengthening the four plants to restore Hg contaminated soil by sodium thiosulfate and fulvic acid.The main conclusions of this experiment were as follows:1.In this field field experiment,in general,when the two activators sodium thiosulfate and fulvic acid were treated at a concentration of 50 kg/mu,the effect of the four plants on soil remediation was relatively good.The total Hg capacity of the heavy metals in the soil was restored to be ramie> rapeseed> cotton> Indian mustard,and the ability of ramie to restore total mercury in the soil was significantly higher than that of the other three plants regardless of the activator treatment concentration.2.The ability to treat effective Hg was cotton> Castor> Indian mustard> rapeseed When Sodium thiosulfate enhanced the phytoremediation of soil available mercury at any treatment concentration.The effective mercury content of the plants restored by various plants is the lowest,and the ability of phytoremediation of soil effective Hg is ramie> cotton> Indian mustard> rapeseed when fulvic acid is used as an activator and the fulvic acid treatment concentration is 50kg/mu,At this time,the effective Hg reduction in the planting ramie soil plot reached 3.9 times than the effective Hg reduction in the rapeseed plot.3.Compared to the use of ramie alone for phytoremediation,and the use of two activators,sodium thiosulfate and fulvic acid,the removal rate of effective mercury increased by 13% and 24%,respectively.For the total mercury removal effect,when the concentration of both activators is 50 kg/mu,the total mercury content in the soil was the lowest after the restoration,and the total removal rate could reach 50%.4.After the application of two activators of sodium thiosulfate and fulvic acid,the average removal rate of effective mercury was increased by 14% and 6.8%,respectively,compared with the case of the Indian mustard alone.In the plots with sodium thiosulfate and fulvic acid concentrations of 100 kg/mu,the total mercury removal rate was 15.5% higher than that of the Indian mustard plot alone.5,Sodium thiosulfate and fulvic acid enhanced rapeseed repair plot experimental results,the treatment concentration of both activators were at 50kg/mu,the effective mercury content in the soil was the lowest,respectively 1.05?g/kg and 1.15?g/kg,compared with the rapeseed area alone,increased by 14.5% and 7.5% respectively.For total mercury,the activation effects of the two activators are similar,and the effect of total mercury removal was best when the concentration is 50 kg/mu.6.The effect of removing effective Hg in the soil was good for a single planted cotton plot,which could reach about 74%.According to the experiment results of the enhanced cotton repair area with sodium thiosulfate and fulvic acid,the best removal effect was in the 50kg/mu area of fulvic acid treatment,and the removal rate increased by 12.6% compared with the cotton planted area alone.