title: Adsorption characteristics of Cu and Zn onto various size fractions of aggregates from red paddy soil.
abstract: Soil aggregate is the basic structure unit of soils and the ability of various size fractions are different in the aspect of adsorbing and transferring heavy metals in the environment. In this study, bulk soil from red paddy field was partitioned into four aggregate-size fractions and their adsorption characteristics for Cu and Zn were studied. Our results showed that: Pseudo-second order model was more successful to fit the adsorption process in the kinetic experiments and the isothermal experiments data can be described well with the Freundlich model as a whole. Due to higher contents in organic matter, CEC and free iron oxide, the <0.002mm fraction was found to have the highest initial sorption rate and maximum adsorption capacity. The adsorption amount of metals increased as the increasing of pH and the percentage of adsorbed metal susceptible to desorption into 0.01M NaNO3 was greater for Zn than for Cu, while their variation trends were quite opposite. More specific adsorption sites in the <0.002mm fraction lead to more desorption amount for this particle size of soil at low pH condition. After 60 days of incubation, Cu and Zn were observed to enrich in the clay-size aggregates with fractions more stable than other particles.
authors.affiliation: College of Environmental Science and Technology, Hunan University, Changsha 410082, China; Key Laboratory of Environment Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, China.
authors.forename: Bin
authors.initials: B
authors.lastname: Huang
authors.affiliation: College of Environmental Science and Technology, Hunan University, Changsha 410082, China; Key Laboratory of Environment Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, China. Electronic address: lizw@hnu.edu.cn.
authors.forename: Zhongwu
authors.initials: Z
authors.lastname: Li
authors.affiliation: College of Environmental Science and Technology, Hunan University, Changsha 410082, China; Key Laboratory of Environment Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, China.
authors.forename: Jinquan
authors.initials: J
authors.lastname: Huang
authors.affiliation: College of Environmental Science and Technology, Hunan University, Changsha 410082, China; Key Laboratory of Environment Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, China.
authors.forename: Liang
authors.initials: L
authors.lastname: Guo
authors.affiliation: College of Environmental Science and Technology, Hunan University, Changsha 410082, China; Key Laboratory of Environment Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, China.
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Nie
authors.affiliation: College of Environmental Science and Technology, Hunan University, Changsha 410082, China; Key Laboratory of Environment Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Wang
authors.affiliation: College of Environmental Science and Technology, Hunan University, Changsha 410082, China; Key Laboratory of Environment Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: College of Environmental Science and Technology, Hunan University, Changsha 410082, China; Key Laboratory of Environment Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, China.
authors.forename: Guangming
authors.initials: G
authors.lastname: Zeng
mesh_terms: D000327:Adsorption; D003300:Copper / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D012275:Oryza; D012989:Soil Pollutants / Q000737:chemistry*; D013816:Thermodynamics; D015032:Zinc / Q000737:chemistry*
chemical_list: D012989:Soil Pollutants; D003300:Copper; D015032:Zinc
keywords: AF(x); Adsorption characteristics; Heavy metals; Red paddy soil; Soil aggregates; V/V; accumulation factor; volume per volume