Natural source of tetraalkyllead in air

THE biological methylation of inorganic mercury in sediments in both aerobic and anaerobic conditions is well known1, and attention has focussed on the possibility of a similar process for lead in the environment. It has been possible to methylate lead in laboratory studies, with the resultant evolution of gaseous tetramethyllead2–4, but there is still considerable doubt as to whether such processes occur in the environment5. A report6 that tetraalkyllead accounts for 10–24% of the total lead in the liver of fresh and frozen samples of cod and 39% of the total lead in mackerel muscle lends credence to the possibility. However, we can now present firm evidence of a natural source contributing tetraalkyllead to the atmosphere.