Formaldehyde and peroxide concentrations in Law Dome (Antarctica) firn and ice cores

Abstract

Peroxide speciation and formaldehyde measurements have been made on ice cores retrieved from Law Dome, Antarctica. Measurements were made for ice deposited during four different periods: modern, pre-industrial Holocene, early Holocene and Last Glacial Maximum (LGM). The data show modern peroxide levels > 50% above pre-industrial levels (at ~ 1.6 μmol L-1) and an absence of methyl hydroperoxide (down to a detection threshold of 0.003 μmol L-1). Formaldehyde levels show a 40% increase from pre-industrial to modern times (rising from ~ 0.07 μmol L-1 to ~ 0.10 μmol L-1), with a further increase and possible seasonality near the surface which we associate with post-depositional processes. Peroxide levels in LGM ice are low, but formaldehyde concentrations are high (at ~ 0.13 μmol L-1) relative to modern levels. Similar high levels of formaldehyde are seen in early Holocene ice (~6900 years BP).