Effects of mobilizing agents on the enhanced phytoremediation of cadmium-contaminated agricultural soil by Pennisetum sinese in farmland
The enrichment and removal of heavy metals by large biomass plants enhanced by mobilizing agents has been a new direction for remediation of contaminated soil.To investigate the enhanced remediation effects of mobilizing agents with different types and dosages on phytoextraction of soil heavy metals,the influences of EDTA,KCl,and oxalic acid(OA)on the phytoremediation of Cd-contaminated farmland soil(0.92 mg·kg-1,pH 5.0)by Pennisetum sinese were compared through field experiment.Results showed that soil total Cd(0.52-0.84 mg·kg-1)decreased significantly after planting,and soil Cd concentration was significantly reduced by EDTA application and medium-and high-dose KCl application(750 kg·hm-2 and 1 125 kg·hm-2).The growth of Pennisetum sinese have not been adversely affected by mobilizing agents,and the shoot biomass(431 mg·plant-1)was increased by low dose KCl(375 kg·hm-2).The accumulation of shoot Cd in all treatments ranged from 0.15 to 0.37 mg·plant-1,with OA and low dose KCl treatments showing the highest accumulation(0.37 mg·plant-1 and 0.32 mg·plant-1,respectively).The Cd was mainly accumulated in leaves(0.53-1.92 mg·kg-1),which accounted for 54.9%-64.2% of the total accumulation in shoot.The bioaccumulation factor(BCF)of Cd in stems(0.67)and leaves(2.09),and translocation factor(TF)for the OA treatment(3.12)were significantly higher than other treatments,indicating that OA enhanced the bioavailability of soil heavy metals and promoted the uptake and accumulation of Pennisetum sinese.Based on this study′s remediation evaluation,at the Cd level of the soil tested,the remediation targets could be achieved by OA and low-dose KCl treatments after 7 and 8 harvests,respectively.For 2.0 mg·kg-1 Cd-contaminated soils,the remediation targets might be achieved after 9 and 10 harvests,respectively.For 0.5 mg·kg-1 Cd-contaminated soil,5 harvests were sufficient.In conclusion,the application of OA and KCl shows the optimized effects on improving slashing soil Cd contamination by Pennisetum sinese,considering both biomass and enrichment capacity.Moreover,by using large biomass plants and enhanced phytoremediation technology,both soil pollution reduction and carbon sequestration were achieved.
enhanced phytoremediation technologysoil heavy metal pollutioncadmiumPennisetum sinesemobilizing agent
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