Degradation and metabolism of tetraethyllead in soils

Abstract

The objective of this study was to determine the disappearance of the leaded gasoline enhancer tetraethyllead (TEL), formation of degradation products, and mass balance in nonsterile and autoclaved Leon and Madison soils. Ethyl-1-14C-labeled TEL was used so that mineralization rates of TEL and mass balance could be determined.14C-TEL in nonsterile and autoclaved surface and subsurface samples of the two soils disappeared rapidly, and ionic ethyllead products, water soluble nonlead organic products and bound residues were rapidly formed. A small fraction (≤7.74%) of14C-TEL in nonsterile soil samples was mineralized to14CO2 in 28 days. Triethyllead (TREL) was the major ionic ethyllead product detected in both nonsterile and autoclaved soils; diethyllead (DEL) was occasionally detected. Recovery of14C from mass balance studies for all nonsterile and autoclaved soil samples after 28 days of incubation was poor, less than 50% of the14C applied. It appears that unknown volatile and/or gaseous organic products were the major degradation products of TEL in soils. Based on the observations of more rapid initial disappearance of14C-TEL, more rapid formation and more rapid disappearance of14C-DEL, and occurrence of14CO2 production in nonsterile soils, it was concluded that both biological and chemical degradation contributed to the degradation of TEL in soils, with chemical degradation being the major factor.