生物炭-植物联合修复对土壤重金属Pb、Cd分布效应

Distribution effect of biochar-phytoremediation on soil heavy metal Pb and Cd

土壤重金属污染是黄河三角洲湿地退化的重要驱动因素之一,Pb、Cd作为该区域典型的重金属,存在较高的潜在生态风险.目前在土壤修复领域,植物修复、化学修复等单一修复方法具有一定的局限性,而生物炭因其强吸附性及丰富的官能团与植物修复技术具有结合的潜力,因此,探究二者联合修复对土壤重金属的分布效应,对于寻求更加绿色高效的修复方法具有重要意义.本研究以黄河三角洲生态恢复区为研究区采集土壤与植物样品,将生物炭与植物修复技术相结合,开展了生物炭与植物联合修复盆栽实验,测定了植物生长期内植物形态特征及重金属水平和垂直分布状况.结果表明,生物炭添加促进了芦苇和盐地碱蓬生长.芦苇生长期内添加生物炭加强了对重金属Pb的固定作用,促进了芦苇对重金属Cd的吸收;盐地碱蓬生长期内添加生物炭降低了对Pb的吸收效果,Cd变化无规律.在土壤垂直方向上,生长期20 d时,仅种植盐地碱蓬或芦苇对土壤Pb修复效果最好,0~10、30~40 cm层土壤Pb含量最低,仅种植盐地碱蓬对Cd修复效果最好,10~20、20~30 cm层土壤Cd含量达到最低;生长期40 d时,仅种植芦苇对Pb修复效果最好,各层土壤Pb含量均达到最低,芦苇种植与生物炭添加联合处理对Cd修复效果最好,各层土壤Cd含量达到最低.

Soil heavy metal pollution is one of the important driving factors for wetland degradation in the Yellow River Delta. Pb and Cd,as typical heavy metals in this area,have high potential ecological risks. Single remediation methods for soil remediation have certain advantages such as phytoremediation and chemical remediation. While biochar has the potential to improve phytoremediation technology due to its strong adsorption and rich functional groups. In the current study,a potted experiment of biochar and phytoremediation was carried out to determine the plant morphological characteristics and the horizontal and vertical distribution of heavy metals during the plant growth period. The results showed that the addition of biochar promotes the growth of Phragmites australis and Suaeda salsa;During the growth of the Phragmites australis,the application of biochar strengthens the fixation of heavy metal Pb and promotes the absorption of heavy metal Cd. The addition of biochar during the growth of the S. salsa reduces the absorption of Pb. The Cd change pattern is not significant;In the vertical direction of the soil,planting S. salsa or P. australis alone has the best effect on Pb remediation in the soil at 20 days in the growth period,and the Pb concentration in the 0~10 and 30~40 cm layer soil is the lowest. S. salsa planted alone has the best Cd remediation effect,at this time 10~20,20~30 cm layer soil Cd concentration reaches the lowest value. At 40 days in the growth period,only planting P. australis had the best Pb remediation effect,when the Pb concentration of each layer reached the lowest. P. australis added with biochar had the best Cd remediation effect. Under this treatment,the Cd concentration in the layer is the lowest.