Effects Of Nano-carbon On Heavy Metal Pollution In Soil Remediation With Hyperaccumulator

Soil heavy metal pollution is becoming more and more serious.Plant remediation is considered to be the most promising remediation technology for heavy metal pollution control.Various strengthening measures have been taken to increase the growth rate,biomass and heavy metal absorption and accumulation of hyperaccumulator,and the application of high-efficiency fertilizers and other agronomic measures have been considered as one of the most effective means to improve the phytoremediation efficiency of hyperaccumulator.Nano-Carbon provides the possibility of improving farmland fertility and remediation of heavy metal pollution due to its huge specific surface area,high surface energy and chemical activity,and strong adsorption.However,most research hotspots are to improve farmland fertility.There is little research on heavy metal pollution.This test takes Solanum nigrum L,Vetiveria zizanioiaes and Brassica juncea L as test object.All parts of this experiment adopts double factors completely randomized block experiment,in which A factor as the applied amount of Nano-Carbon,B factor as the applied amount of heavy metals.Based on the pot experiment of remediation of lead-contaminated soil by Vetiveria zizanioiaes,the experiment of remediation of cadmium-contaminated soil by Solanum nigrum L and the experiment of remediation of cadmium and lead-contaminated soil by Brassica juncea L,the effect of Nano-Carbon on the remediation of heavy metal pollution in hyperaccumulator was studied.The main research contents and results are as follows:(1)Pot experiment of Vetiveria zizanioiaes repairing lead-contaminated soil: Nano-carbon significantly increased the biomass and Pb accumulation of Vetiveria zizanioiaes.The increase of dry weight above ground is: 14.54% ～ 40.53%,and the increase of dry weight of root is: 5.58% ～ 44.65%.The increase rate of Pb accumulation in the aerial part is: 9.95% ～ 42.05%,and the increase rate of Pb accumulation in the root is: 28.16% ～ 44.02%.The above-ground S1 transport coefficient showed a decreasing trend,the above-ground S2 transport coefficient showed an increasing trend,and the above-ground S2 and root enrichment coefficients showed an increasing trend,with no significant difference.Through the analysis of the restoration efficiency(PPE)calculated by the removal of heavy metals in plants and the restoration efficiency(SPE)calculated by the reduction of heavy metals in the soil,it was found that the increase in PPE and SPE increased with the increase in the amount of Nano-Carbon applied.The increase in PPE is: 5.78% ～ 27.74%,and the increase in SPE is: 9.30% ～ 24.74%.(2)Pot experiment of Solanum nigrum L repairing cadmium-contaminated soil: After applying NanoCarbon,the biomass of Solanum nigrum L significantly in Cd5,Cd10,and Cd20 treatment groups.These three groups of aerial parts increased by 2.90% ～ 17.52,and the roots increased by 2.6% ～ 17.05%.Nanocarbon can increase the accumulation of Cd,the above-ground increase is: 1.33% ～ 8.95%(except Cd5-NC1 and Cd40-NC1),the increase of Cd accumulation in the root is: 3.89% ～ 14.65%,when the cadmium concentration is 5mg/kg,the increase effect of the whole group is the best.The transport coefficient decreased slightly and the enrichment coefficient increased,but there was no significant difference.Through the analysis of PPE and SPE indicators,it was found that the increase in PPE and SPE increased with the increase in the amount of Nano-Carbon applied.The increase in PPE is: 2.34% ～ 17.74%,and the increase in SPE is: 4.81% ～ 19.74%.(3)Pot experiment of Brassica juncea L repairing cadmium and lead contaminated soil: Nano-Carbon significantly increased the dry weight of Brassica juncea L,the dry weight of the above ground increased by 5.26% ～ 30.8%,and the dry weight of the root increased by 4.24% ～ 28.65%,the largest increase in the Cd10Pb1000 treatment group.After the application of Nano-Carbon,the accumulation of Brassica juncea L on Cd and Pb was promoted,but there was no significant difference,and the overall increase was the largest in the Cd20Pb2000 treatment group.Nano-Carbon has little effect on the enrichment and transfer coefficients of cadmium and lead in Brassica juncea L.Through the analysis of PPE and SPE indicators,it was found that the increase in PPE and SPE increased with the increase in the amount of Nano-Carbon applied.The increase in PPE for cadmium is: 3.54% ～ 21.34%,and the increase in SPE is: 7.31% ～ 20.74%.The PPE growth rate of lead is: 4.53% ～ 21.43%,and the SPE growth rate is: 7.85% ～ 23.03%.The effect of the increase in middle level pollution is the best.In summary,different treatments can promote the hyperaccumulator to remediate contaminated soil.Among them,PPE and SPE of Vetiveria zizanioiaes have the largest increase,PPE and SPE of Solanum nigrum L have the smallest increase,and PPE and SPE for Pb have a greater increase than Cd PPE And SPE,the largest increase in PPE and SPE for middle level contaminated soil.Therefore,among the three hyperaccumulators,Nano-Carbon is more suitable for the experiment of Vetiveria zizanioiaes to repair leadcontaminated soil,more suitable for Pb-contaminated soil,and more suitable for medium-high lead-contaminated soil phytoremediation.This experiment provides a theoretical basis for the future discussion of nano-carbon to promote hyperaccumulator to repair cadmium and lead pollution.