Study On Simultaneous Removal Of Mercury And Polycyclic Aromatic Hydrocarbons From Soil By Energy Plants

With the increasing number of abandoned and polluted sites in China,it is urgent to repair and improve the environment.In this study,the contaminated soil of the coking plant was selected and the representative pollutants of mercury and polycyclic aromatic hydrocarbons (pahs) were added to the contaminated site.Jerusalem artichokes were used as remediation plants to explore the phytoremediation effect of the site contaminated by heavy metals and organic compounds.The following main conclusions are drawn:1.Hg concentration of 4.5 mg/kg,ΣPAHs concentration of 240 mg/kg,compound pollution status has no obvious inhibition for the growth of Jerusalem artichoke;With the increase of pollutant concentration,plant height,leaf area,biomass (DW),chlorophyll content,and root activity all decreased,and the influence of high PAHs pollution on plant growth was more significant than that of high Hg pollution.The activities of superoxide dismutase (SOD) and peroxidase (POD) in Jerusalem artichos leaves increased first and then decreased with the increase of Hg concentration,and decreased with the increase of PAHs concentration.The content of lipid membrane peroxidation product (MDA) increased with the increase of pollutant concentration,indicating that Jerusalem artichoke had a positive resistance response to pollution stress,but pollution still had a negative effect on Jerusalem artichoke.2.The high concentration of PAHs and mercury reduced the diversity of soil microorganisms,and the diversity of soil microorganisms changed when planting Jerusalem artichoke compared with no cultivation.By comparing the phylum and genus levels,the microbial community structure of different pollution groups is different,and the overall ecological potential of the dominant community after planting Jerusalem artichoke is improved.The analysis of PCA and CCA at the OUT level further proved that the cultivation of Jerusalem artichoke has an influence on the composition of the microbial community in the contaminated soil.Mercury and PAHs caused the change in the composition of the microorganism.The concentration of PAHs at the experimental concentration contributed more than the difference in the composition of the microorganism.3.After 90 days of planting Jerusalem artichoke,the distribution of mercury in Jerusalem artichokes is the root> leaf>stem,the root is the main organ of artichoke to accumulate mercury.The content of mercury in Jerusalem artichoke roots and leaves increases first with the increase of soil mercury content,and then decreases slightly.The mercury content in the stem increases as the soil mercury content increases.The Bioconcentration factor(BCF) of Jerusalem artichoke in the high Hg group (CG2/CG3/CG4) is greater than 1,reaching a maximum of 5.90,indicating that Jerusalem artichoke is suitable for remediation of medium and high mercury-contaminated soil,but the Jerusalem artichoke translocation factor(TF) is less than 1,indicating that the root of Jerusalem artichoke blocks the upward transmission of Hg.4.High concentrations of PAHs group EPAHs removal rate was 70.86%,compared with not planting group improved significantly.Compared with the non-planted group,after planting Jerusalem artichoke,the content of most of the detected PAHs components decreased significantly,which shows that planting Jerusalem artichoke has an important role in the degradation of PAHs.Whether planted or not planted,the content of 10 PAHs decreased significantly (10% to 100%),indicating that the degradation of PAHs mainly depends on the effect of micro-ecology in the soil.2.The removal rate of 3-ring PAHs shows a trend of increasing with the increase of PAHs concentration,which proves that the form of polycyclic aromatic hydrocarbons added to the soil affects their sensitivity to dissipation.5.With the increase of PAHs concentration,the accumulation of mercury in Jerusalem artichoke stems and leaves increased,indicating that polycyclic aromatic hydrocarbons can promote the extraction of mercury from Jerusalem artichoke aerial parts.With the increase of mercury concentration,the dissipation of most PAHs components did not change significantly,indicating that under the experimental compound pollution concentration,the biggest limiting factor for repairing compound pollution by Jerusalem artichoke is PAHs instead of mercury.Jerusalem artichoke performs well in the remediation of mercury and PAHs compound contaminated sites and is suitable for the remediation of compound contaminated sites.