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Lead concentrations from an Antarctic snow pit show the pattern of Pb reaching the Antarctic atmosphere over the last 70 years. Between 1920 and 1950, the Pb concentration shows significant variations around a mean of about 2.5 ng kg−1. Between 1950 and 1980, there is a clear increase to 6 ng kg−1, with an apparent reduction after that. A few high concentrations in the late 1970s are probably due to local contamination from aircraft using leaded gasoline (petrol). Excluding these anomalously high values, the chronological pattern in lead concentrations can be reconciled with estimates of emissions from vehicles and metal production processes in the southern hemisphere.

[1] Formaldehyde (HCHO) measurements in snow and shallow firn at three Antarctic sites gave concentrations around 6 ppbw in surface snow and 1 ppbw and lower below 1–2 m depth. The variable concentration patterns in shallow snow and firn result from temperature-dependent uptake and release of HCHO in response to annual temperature cycles. Deeper concentrations are constant with depth, and apparently reflect average atmospheric concentrations. This implies that after accounting for differences in temperature and accumulation, changes in ice-core HCHO concentrations with depth should linearly reflect changes in atmospheric HCHO over time. Modeling of observed HCHO profiles in the snow implies that degassing of HCHO from surface snow likely contributes a significant fraction of the HCHO found in the boundary layer in spring and summer at all three sites. Based on modeling of air-snow exchange and atmospheric photochemistry, summer HCHO levels are estimated to be on the order of 100–200 pptv.