Volatilization of Organotin Species from Municipal Waste Deposits: Novel Species Identification and Modeling of Atmospheric Stability

摘要

Organotin compounds are used as pesticides and fungicides as well as additives in plastics. This study identifies the de novo generation of novel volatile organotins in municipal waste deposits and their release via landfill gas. Besides tetramethyltin (Me_4Sn), a strong neurotoxin, and 5 previously reported organotins, 13 novel ethylated, propylated, and butyiated tetraalkyltin compounds were identified. A concentration of 2-4 μg of Sn m~(-3) landfill gas was estimated for two landfill sites in Scotland. The atmospheric stability of Me_4Sn and methylated tin hydrides was determined empirically in a static atmosphere in the dark and under UV light to simulate night- and daytime conditions. Theoretical calculations were carried out to help predict the experimentally obtained stabilities and to estimate the relative stabilities of other alkylated species. Assuming first-order kinetics, the atmospheric half-life for Me_3SnH was found to be 33 ± 16 and 1311 ± 111 h during day- and nighttime conditions, respectively. Polyalkyiation and larger alkyl substitutes tend to reduce the atmospheric stability. These results show that substantial concentrations of neurotoxic organotin compounds can be released from landfill sites and are sufficiently stable in the atmosphere to travel over large distances in night- and daytime conditions to populated areas.