Distribution coefficients of tin in Japanese agricultural soils and the factors affecting tin sorption behavior

Sorption behavior of tin (Sn) in Japanese agricultural soils was studied. Soil–soil solution distribution coefficient (Kd) of Sn (Kd-Sn) for 142 soil samples ranged between 128 and 1 590 000 L kg−1 with the geometric mean of 12 400 L kg−1. The Kd-Sn values for Andosol tended to be higher than those of the other soil groups. Among the relationships between Kd-Sn values and soil properties, a high correlation was observed for soil active-Al (Al-(hydr)oxide and Al–humus complex) amount and Kd-Sn. The pH effect on Sn sorption was also investigated. The results suggested that the low pH condition enhanced the Sn sorption in soils. The soil-sorbed Sn fractions in each type of soil material were also evaluated with selective extraction methods. The results showed that most of the soil-sorbed Sn was as organic matter bound or Al/Fe-(hydr)oxide-bound forms.