| Heavy metal pollution leads to soil degradation,reduced crop yields and quality,worsens hydrological conditions and endangers human health and life.This study is proposed to use the soil of the mining area pollution site as the soil sample of heavy metal pollution,to take biochar as the soil additive,and to use the Vetiveria Zazanioides as the phytoremediation.By studying the effects of adding biochar and planting Vetiveria Zazanioides on the form and content of heavy metals in contaminated soil,the physiological and biochemical characteristics of Vetiveria Zazanioides,the activity of soil microorganisms and the structure of soil microbiome.The feasibility of the combination of biochar and Vetiveria Zazanioides in the soil restoration of heavy metal pollution was discussed.In order to provide theoretical basis and practical guidance for the rational use of biochar in cooperative plant measures to repair heavy metal pollution of soil.Ten treatments were set up in the Potted culture system: mining soil(K),mining soil + 1% biochar(KC1),mining soil + 2% biochar(KC2),mining soil + 4% biochar(KC3),mining soil + 10% biochar(KC4),mining soil + Vetiveria Zazanioides(KG),mining soil + 1% biochar + Vetiveria Zazanioides(KGC1),mining soil + 2% biochar + Vetiveria Zazanioides(KGC2),mining soil + 4% biochar + Vetiveria Zazanioides(KGC3),mining soil + 10% biochar+ Vetiveria Zazanioides(KGC4).The main research results are as follows:(1)The single biochar can effectively improve the physical and chemical properties of heavy metal pollution soil.Compared with the control K,KC3 and KC4 treated soil pH increased by 21.91% and 55.87%,respectively.Treatment of KC1,KC2,KC3 and KC4 increased soil SOC by 5.57%,13.18%,13.05% and 16.91% respectively compared to control K,and soil TN increased by 2.86%,3.18%,6.81% and 2.86% respectively.Single biochar can passiva heavy metal pollutants in soil.Compared with the control K,the content of acid-soluble and reducable-state heavy metals Cd,Pb,Cu and Zn in the treated soil was significantly reduced,and the content of the oxidizing and residual heavy metals Cd,Pb,Cu and Zn were significantly increased.Single biochar increased the microbial activity of heavy metal pollution soil,and compared with control K,KC1 and KC4 treated soil basic respiratory strength increased significantly by 20.07 % and 12.45 %.The carbon amount of microorganisms treated in KC1,KC2,KC3 and KC4 increased by 22.75%,11.93%,29.70% and 50.59% respectively compared to the control K.Carbon treatment on the activity of contaminated soil dehydrogenase,hydrogen peroxide and pyridine enzymes showed a certain role in promoting the structure of the soil microbiome of heavy metal pollution,and there was no significant difference in the content of soil microbes PLFAs and microbiodiversity between treatments.(2)The addition of biochar can significantly promote the photosynthesis and biomass of the Vetiveria Zazanioides stalks in the soil contaminated by heavy metals.Compared with the controlled treatment KG,the biomass of the treatment of KGC3 and KGC4 sage stem leaf significantly increased by 12.70% and 16.93%.The addition of biochar will reduce the amount of heavy metals in the effective state and relieve the biotoxicity of heavy metal pollutants to the Vetiveria Zazanioides.Compared with the comparison,carbon treatment can effectively reduce the content of heavy metal Cd,Cu and Zn in the Vetiveria Zazanioides roots,but there is no significant effect on the heavy metal Pb content.Compared with KGC1,KGC2,KGC3 and KGC4,the MDA content and the MDA content in the sage stem were reduced by 36.01%,29.59%,32.54% and 48.24%,respectively,and the MDA content in the Vetiveria Zazanioides roots system decreased by 16.23%,11.18%,and 27.46%,respectively.and 24.51%.The addition of biochar can significantly reduce the enzyme activity of Vetiveria Zazanioides root resistance in soil contaminated by heavy metals,and compared with the control KG,the SOD activity of processing KGC1,KGC2,KGC3 and KGC4 Vetiveria Zazanioides root system decreased by 11.53%,16.97%,47.40% and 61.33%,respectively.The activity of the Vetiveria Zazanioides roots POD decreased by 35.59%,25.81%,55.36% and 75.35%,respectively.(3)Planting Vetiveria Zazanioides can effectively reduce the heavy metal content in the contaminated soil.Compared with treatment K,the heavy metal Cd,Pb,Cu and Zn in KG soil were reduced by 49.09%,27.53%,26.61% and 58.27%,respectively.The removal rate of Cd,Cu and Zn in heavy metal contaminated soil was not significantly affected by the treatment of the soil with biochar,and the removal of heavy metal Pb in the soil was promoted,and the content of KGC4 soil Pb was significantly reduced by 31.42% compared with the treatment of KG.The distribution of biochar by Vetiveria Zazanioides has a certain effect on the microbial activity of contaminated soil.Compared with the control KG,the basic respiratory strength of KGC4 was significantly increased by 22.16%.The carbon content of soil microorganisms treated for KGC1 and KGC4 was significantly increased by 52.47% and 24.66% compared to the control KG.The treatment of Vetiveria Zazanioides with biochar was significantly promoted to the activity of FDA hydrolysase,dehydrogenase,hydrogen peroxide and pyrethlase in contaminated soil.The distribution of biochar by Vetiveria Zazanioides can effectively improve the content of microbiome and the total amount of PLFAs in the soil contaminated by heavy metals.Compared with the controlled KG,the total amount of soil microbiological PLFAs treated with KGC1,KGC2,and KGC4 increased by 28.97%,5.74% and 16.02%,respectively.The distribution of different doses of biochar by scented grass has different effects on the content of gram-positive bacteria,gram-negative bacteria,eukaryotic microorganisms,line-release bacteria,plexus root fungus and fungal PLFAs in soil.To sum up,the addition of biochar can effectively improve the physical and chemical properties of the soil,passivation of heavy metal pollutants in the soil,reduce the coercive effect of heavy metal pollutants on the Vetiveria Zazanioides,help to pollute the physiological growth of the Vetiveria Zazanioides in the soil,improve the effect of heavy metal pollution soil repair,Therefore,it is feasible to apply biochar and Vetiveria Zazanioides to heavy metal contaminated soil restoration. |
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