Keywords: 
• micro-aggregates /
• soil /
• heavy metal /
• sorption

Abstract: In this study, size fractions of micro aggregates were separated from two paddy soils-Huangnitu and Wushantu(Ferric Accumulic Stangnic Anthrosols and Gleyic Stangnic Anthrosols).The sorption and desorption of Cu2+ by the particle separates were studied by using equilibrium adsorption method. Adsorption of Cu2+ by different size fractions of the micro aggregates fitted well the Freundlich and Langumir isotherm with different adsorption amount, as being well reported for the bulk soil samples. The maximum adsorption amount of each particle size fraction was between 1667-3333 mg·kg-1, and the size fractions of0.002mm and 2.00-0.25mm had the greatest adsorption capacity. The adsorption capacity of the size fractions was well correlated with the content of organic matter and free iron oxides. When desorped under 0.01 mol·l-1 CaCl2, the clay fraction and coarse sand fractions had the strongest capacity for Cu2+ adsorption compared to other fractions. Desorpion amounts of Cu2+ of two paddy soils are different despite being decreased with desorption times.