摘要
采用等温平衡法研究了3种伴随阴离子(Cl-、SO24-、H2PO-4)下赤红壤和水稻土Pb2+和Cd2+的吸附解吸规律,以阐明不同阴离子影响铅和镉有效性的大小。结果表明,Pb2+、Cd2+的吸附量均随平衡液中Pb2+、Cd2+浓度增加而增大,其关系较好地符合Freundlich方程X=ACB。方程中表征吸附容量的参数A表明,3种阴离子影响土壤铅吸附大小顺序依次为H2PO-4>SO24->Cl-;赤红壤上阴离子的影响大于水稻土。两种土壤上铅的解吸量平均仅占吸附量的0.06%～1%,说明土壤吸附铅以专性吸附为主;而镉在赤红壤上解吸率<3%,水稻土上解吸率为1.4%～19.2%,表明镉在赤红壤仍以专性吸附为主,水稻土上还存在部分非专性吸附。根据吸附结果认为,土壤中氯离子的存在可增加铅、镉的有效性,而磷酸根是铅、镉最好的稳定剂。
Using isotherm method, adsorption-desorption of Pb and Cd by red latersol and paddy soil were measured under existing three kinds of anion ions （Cl-, SO4^2-, H2PO4） for finding out the effects of different accompanying anions on availability of Pb and Cd in the two soils. The results showed that the adsorption amount of Pb and Cd increased with the increasing concentration of Pb and Cd, the relationship could be well described by Freundlich isotherms equation X=A C^8. Freundlich metal retention parameters A, indicated that the effect order of anion - 2- ions was similar in red latersol and paddy soil, being H2PO4^-〉SO4^2- 〉Cl^-, but the effects of anion ions on Pb and Cd adsorption by red latersol were higher than that of paddy soil. Desorption rate of Pb were all from 0.06% to 1%, indicating that Pb was mainly specifically adsorbed by two soils; while, the desorption rate of Cd was less than 3% in red latersol and was from 1.4% to 19.2% in paddy soil, implying that Cd was specifically adsorbed by red latersol and there was partially non-specific adsorption in paddy soil. Cl^- could increase available Pb, Cd in two soils and H2PO4^- had an adverse effect.
出处
《农业环境科学学报》
CAS
CSCD
北大核心
2007年第1期252-256,共5页
Journal of Agro-Environment Science
基金
国家重点基础研究发展规划项目(2002CB410809)
北京市自然科学基金(6062026)
关键词
铅
镉
伴随阴离子
吸附-解吸
Pb
Cd
accompany anion
adsorption-desorption
