引用本文:白利勇,季慧慧,孙文轩,黄明丽,刘可忠,李玲玉,颜冬云.粉煤灰中重金属Pb/Cr/Cu在土壤—小白菜中的迁移与形态转化[J].土壤学报,2019,56(3):682-692.
BAI Liyong,JI Huihui,SUN Wenxuan,HUANG Mingli,LIU Kezhong,LI Lingyu,YAN Dongyun.Morphological Transformation and Migration of Heavy Metals (Pb, Cr and Cu) in Coal Ash Applied to the Soil-Chinese Cabbage System[J].Acta Pedologica Sinica,2019,56(3):682-692
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粉煤灰中重金属Pb/Cr/Cu在土壤—小白菜中的迁移与形态转化
白利勇,季慧慧,孙文轩,黄明丽,刘可忠,李玲玉,颜冬云
青岛大学环境科学与工程学院
摘要:
以两种粒径粉煤灰与莱西棕壤按不同比例混匀后连续进行了四批次小白菜生长周期试验,采用欧共体标准物质局提出的三步提取法(简称BCR法)研究施灰土壤中铅(Pb)、铬(Cr)和铜(Cu)四种化学形态的转化特征,并通过计算小白菜对重金属的富集系数和转移系数,分析土壤重金属在小白菜中的迁移特性与生物利用率。结果表明:在小白菜种植的整个周期,各处理施灰土壤中Pb、Cr和Cu均以残渣态为主,含量随种植批次增加而减少;Pb、Cr的可提取态含量占15%以上,乙酸溶解态含量随种植批次增加而增加,Cu的可提取态含量占55%以上,乙酸溶解态含量随种植批次增加而减少。小白菜对三种重金属的富集能力表现为:Cu>Cr>Pb,且均小于临界值1,因此,相较Pb和Cr,Cu的生物利用性更强。小白菜由根部向地上可食部分转移系数大于1,转移能力表现为:Cr>Cu>Pb,因此Cr在小白菜中迁移能力更强。
关键词:  粉煤灰  重金属形态  富集系数  转移系数
DOI:10.11766/trxb201807250344
分类号:
基金项目:山东省重点研发计划(公益类专项,2017GNC11116)资助
Morphological Transformation and Migration of Heavy Metals (Pb, Cr and Cu) in Coal Ash Applied to the Soil-Chinese Cabbage System
BAI Liyong1, JI Huihui2, SUN Wenxuan2, HUANG Mingli2, LIU Kezhong2, LI Lingyu2, YAN Dongyun2
1.College of Environmental Science and Engineering,Qingdao University;2.College of Environmental Science and Engineering, Qingdao University
Abstract:
【Objective】So far little has been reported in the literature about morphological transformation of heavy metal elements in coal ash applied as soil amendment and hazards of long-term application of the coal ash to the soil environment and human health, though a quite number of researchers reported that application of coal ash in agriculture is of positive significance. However, statistics of the literatures both at home and abroad indicates that most of their conclusions were based on cultivation of only one crop and analysis of yield and quality of the crop. Therefore, this paper aimed to explore transformation, migration and concentration trend of Pb, Cr and Cu in the soil-Chinese cabbage system under long-term continuous cultivation, in an attempt to provide a certain theoretical basis and support with data for use of coal ash as amendment in agriculture and ecological environment. 【Method】Chinese cabbage was cultivated for four consecutive seasons in pots of brown soil amended with coal ashes different in particle size, i.e. fine coal ash collected with a bag-type dust remover and coarse coal ash collected from a boiler furnace and different in rate, separately. In this project, samples of the soils mixed with coal ash were collected for analyses of chemical fractions of heavy metals (Cr, Cu and Pb) by following the three-step sequential extraction procedure laid down by the EC Reference Bureau (BCR). Contents of heavy metals (Cr, Cu and Pb) in the roots and edible parts of the cabbage were also determined for calculation of enrichment coefficients and transfer coefficients of the heavy metals in the Chinese cabbage and for analysis of migration behavior and bioavailability of the heavy metals in the Chinese cabbage. 【Result】Contents of HOAc(acetic acid) soluble fractions of Pb and Cr in different coal ash treatments were measured, displaying an order of 150 g·kg-1 coarse coal ash > 150 g·kg-1 fine coal ash > 50 g·kg-1 coarse coal ash > 50 g·kg-1 fine coal ash > CK, which indicates that both application rate and particle size of coal ash affected the fraction of HOAc soluble Pb or Cr in content. Analysis of distributions of Pb, Cr and Cu relative to form in the soil exhibits an order of residual fraction > reducible fraction/oxidable fraction > HOAc soluble fraction. All the findings demonstrate that Pb, Cr and Cu remains mainly as residue in the treated soils, and their contents decrease with the cultivation going on season by season. The fraction of extractable Pb and Cr accounted for 150 g·kg-1 or more, and that of HOAc soluble ones increased with the cultivation going on season by season. However, both the fractions of extractable Pb and Cr accounted for 55% or more, and the fraction of HOAc soluble ones decreased with the cultivation going on season by season. Heavy metal enrichment ability of the plant varied in the order of Cu > Cr > Pb, all of which were lower than the threshold value of 1. Therefore, compared with Pb and Cr, Cu was higher in bioavailability. The contents of heavy metals in the root of Chinese cabbage were lower than their respective ones in the edible part, and their transfer coefficients were all > 1. Their transfer capacity was in the order of Cr > Cu > Pb, so the migration ability of Cr in Chinese cabbage was higher than the other two. 【Conclusion】With the plant growing on, contents of the heavy metal residues in the treated soils decrease gradually, while contents of the HOAc soluble fractions increase gradually, indicating that the residues become HOAc soluble. The organic acids secreted from roots of the Chinese cabbage activate the coal ash applied to soil, thus making the heavy metals in the soil gradually transform from residual form into potentially available form and/or HOAc soluble form, thereby enhancing bioavailability of the heavy metals gradually. Although the heavy metal enrichment coefficients of the Chinese cabbage are low, the heavy metal transfer coefficients are high, which will pose a safety hazard with the edible part of the Chinese cabbage.
Key words:  Coal ash  Heavy metal form  Enrichment coefficient  Transfer coefficient