|Huang, J-H; Schwesig, D; Matzner, E: Organotin compounds in precipitation, fog and soils of a forested ecosystem in Germany, Environmental Pollution, 130, 144-186 (2004)|
Organotin compounds (OTC) are highly toxic pollutants and have been mostly investigated so far in aquatic systems and sediments. The concentrations and .uxes of di.erent organotin compounds, including methyl-, butyl-, and octyltin species in precipitation and fog were investigated in a forested catchment in NE Bavaria, Germany. Contents, along with the vertical distribution and storages in two upland and two wetland soils were determined. During the 1-year monitoring, the OTC concentrations in bulk deposition, throughfall and fog ranged from 1 ng Sn l-1 to several ten ng Sn l-1, but never over 200 ng Sn l-1. The OTC concentrations in fog were generally higher than in throughfall and bulk deposition. Mono-substituted species were the dominant Sn species in precipitation (up to 190 ng Sn l-1) equaling a .ux of up to 70 mg Sn ha-1 a-1. In upland soils, OTC contents peaked in the forest .oor (up to 30 ng Sn g-1) and decreased sharply with the depth. In wetland soils, OTC had slightly higher contents in the upper horizons. The dominance of mono-substituted species in precipitation is well re.ected in the contents and storages of OTC in both upland and wetland soils. The ratios of OTC soil storages to the annual throughfall .ux ranged from 20 to 600 years. These high ratios are probably due to high stability and low mobility of OTC in soils. No evidence was found for methylation of tin in the wetland soils. In comparison with sediments, concentrations and contents of organotin in forest soils are considerably lower, and the dominant species are less toxic. It is concluded that forested soils may act as sinks for OTC deposited from the atmosphere.