【摘要】 用理化性质不同的废纸、木屑、脱水污泥等原材料在600℃限氧条件下热裂解分别制备了3种生物炭,继而利用根袋法盆栽实验研究了这3种生物炭的施用对生长于矿区重金属污染土壤中的小麦和玉米幼苗的根际和非根际土壤中有效态有害元素以及幼苗根系有害元素富集的影响。结果表明,施用这3种生物炭的小麦和玉米幼苗根际与非根际土壤中CaCl2提取态、EDTA提取态和稀HCl提取态As、Cd和Pb含量均低于未施用生物炭的对照处理组,并且随着生物炭施用量从0.5%增加到5%,3种提取态As、Cd和Pb含量降低更为明显,但生物炭处理对非根际土壤中提取态As、Cd和Pb的降低总体比根际土壤明显。施用3种理化性质不同生物炭的土壤中有效态As、Cd和Pb含量与有效态提取剂(CaCl2、EDTA和稀HCl)和被提元素种类(As、Cd和Pb)相关,但未表现出一致性的规律。小麦和玉米幼苗根际和非根际土壤中CaCl2提取的水溶态As、Cd和Pb无显著差异,而部分EDTA及稀HCl提取的可交换态、碳酸盐结合态有害元素、铁锰氧化物和有机结合态As、Cd和Pb存在显著差异。小麦和玉米幼苗根系As、Cd和Pb的富集量均低于未施用生物炭的对照处理组,并且随着生物炭施用量从0.5%增加到5%,提取态As、Cd和Pb的含量降低更为明显。因而,施用生物炭有助于降低有害元素的植物富集风险。更多还原

【Abstract】 Biochar is a carbon-rich composite derived from the slow pyrolysis of biomass feedstock in the absence of oxygen. It has been widely investigated for carbon sequestration,soil remediation/restoration,and soil fertility. In this study,biochars were prepared through theslow pyrolysis of scrap paper,wood chips,and dehydrated sludge under limited oxygen at 600 ℃. Different levels(0.5% and 5%)of the re?sulting biochars were added to soil from a lead-zinc mining area of Qixia in Nanjing;the soil was contaminated with heavy metals. Laborato?ry experiments were then conducted on corn(Zea mays L. cv. Suyu 44)and wheat(Triticum aestivum L. cv. Nongmai 88)seedlings via rhi?zo-bag pot cultures. The bioavailabiliy of Pb,As,and Cd in the rhizosphere and non-rhizosphere soil of the seedlings,and the accumulationof the former in the roots of the seedlings,were investigated. The results showed that the CaCl2-extractable,EDTA-extractable,and dilute-HCl-extractable fractions of As,Cd,and Pb in the rhizosphere and non-rhizosphere soils of the seedlings in the groups treated with the bio?chars were lower than those in the control group,to which the biochars were not added. With the increase in biochars levels from 0.5% to5%,the extractable As,Cd,and Pb content decreased significantly;however,the reduction in the extractable fractions of As,Cd,and Pb inthe non-rhizosphere soils was generally clearer than that in the rhizosphere soils. The effects of biochars with different physicochemicalproperties on the extractable As,Cd,and Pb in soils were related to the extractants(CaCl2,EDTA,and dilute HCl)and the extracted ele?ments(As,Cd,and Pb),but no unified rules were observed. There were no significant differences between the rhizosphere and non-rhizo?sphere soils from which the water-soluble As,Cd,and Pb had been extracted by CaCl2,but some of the exchangeable and carbonate-bound,iron/manganese-bound,and organic matter-bound fractions extracted by EDTA and dilute HCl differed significantly. The As,Cd,and Pbcontent in the roots of the seedlings in the groups treated with biochars were lower than those in the control group. With the increase in bio?chars from 0.5% to 5%,the decrease in contents of As,Cd,and Pb was more significant;wood chip-and sludge-based biochars were better at reducing As,Cd,and Pb enriched in the roots of the seedlings than the scrap paper-based biochar.更多还原