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Cd(II)与As(V)在一株土壤细菌Delftia sp.上共吸附研究
李杨, 周丽, 杜辉辉, 刘玉玲, 杨蕊嘉, 雷鸣, 铁柏清
湖南农业大学资源环境学院
摘要:
在土壤中,重金属(如Cd、Pb)和类金属(As、Sb)的复合污染非常复杂,而目前,还未有研究关注Cd、As在土壤微生物界面的共吸附行为。本研究利用宏观批吸附实验、电位滴定及光谱学手段探讨Cd(II)-As(V)在一株土壤细菌(Delftia sp.)表面的共吸附特点和机制。结果表明:Delftia sp.细菌表面富含羧基、磷酰基、氨基和羟基等官能团,解离常数(pKa)分别为4.57、7.04、8.22和10.45;当pH<5时,Cd(II)在复合体系的吸附量大于单一体系,pH>5时,Cd(II)在复合和单一体系吸附量差异不大;在pH 2–9范围内,As(V)在复合体系的吸附量都小于单一体系;细菌表面的羧基和少量氨基参与了Cd、As在细菌表面的络合反应,且Cd、As会在这些位点发生竞争作用。本研究证实,土壤pH是影响Cd、As在微生物表面共吸附的重要因素.
关键词:  土壤细菌      复合污染  共吸附
DOI:
分类号:S153.3
基金项目:国家自然科学基金项目(41907015)和中国博士后科学基金面上项目(2019M662782)
Co-adsorption of Cd(II) and As(V) to a soil bacterium Delftia sp.
Li Yang, Zhou Li, Du Huihui, Liu Yuling, Yang Ruijia, Lei Ming, Tie Boqing
Hunan Agricultural University
Abstract:
In soils, heavy metals (e.g., Cd, Pb) and metalloids (e.g., As, Sb) combined pollution is very complicated, to date however, no information is available concerning the coadsorption characteristics of cadmium and arsenic to soil microbes. In this study, batch adsorption experiment coupled with potentiometric titration and spectroscopy techniques were applied to investigate the coadsorption mechanisms of Cd(II) and As(V) to a soil bacterium Delftia sp. The results show that: carboxyl, phosphoryl, amino and hydroxyl groups abound in bacterial surfaces, with dissociation constant (pKa) of 4.57, 7.04, 8.22 and 10.45, respectively; batch results show that the adsorption of Cd in binary system is larger than that in single system at pH<5, whereas no noticeable differences are observed at pH>5; For As(V), the presence of Cd inhibits As adsorption over the whole pH ranges (2–9). XPS results demonstrate that the carboxyl and amine groups participate in the complexation of heavy metal on bacterial surfaces, and Cd and As may compete with each other on these adsorption sites. This study therefore proposes that soil pH is an important factor that influences the coadsorption of Cd and As to microbes.
Key words:  Soil bacteria  Cadmium  Arsenic  Combined pollution  Coadsorption

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