A snow/firn four-century record of polycyclic aromatic hydrocarbons (PAHs) and polychlorobiphenyls (PCBs) at Talos Dome (Antarctica)

A four-century record of fourteen polycyclic aromatic hydrocarbons (PAHs) and seven polychlorobiphenyls (PCBs) was obtained from two snow/firn cores gathered at Talos Dome (Antarctica) in order to assess the contribution of human activities to global environmental pollution. The total concentrations of Sigma PAH(14) and Sigma PCB7 were 0.7 ng/l and 0.06 ng/l in the deepest firn sample analyzed, and 3.4 ng/l and 0.22 ng/l in surface snow samples deposited over the last few years, respectively. Our data highlighted the presence of PAH maxima in the concentration depth profile, which correlated with non-sea salt sulphate maxima associated with the major known volcanic eruptions in the period 1600-1930. PAHs showed the highest concentration in the core (4.6 ng/l) at a depth of about 27.8 m (14.8 m water equivalent), here named the "Tambora PAH excess", in relation to the Tambora eruption (1815 A.D.), the largest in recorded history. Surprisingly the data also revealed the presence of synchronous PCB maxima, with a well defined peak (0.14 ng/l) at a depth of 27.8 m. Between 1930 and 2002, PAHs showed an overall 50% increase, with a slope of about 0.013 ng l(-1) year(-1). This can be predominantly attributed to the emission of incomplete combustion processes of organic matter related to anthropogenic activities. PCBs show a much higher increase (+ 200%) with a slope of 0.0034 ng l(-1) year(-1) in a very limited period (1930-1980) which is almost totally due to the massive industrial production and use of PCBs, here named "industrial PCB excess". The slight tendency of PCBs to a constant level from 1980 to 2002 might be attributed to the reduction in the industrial production of PCBs and the restricted use only in totally enclosed systems which started in many countries in the late 1970s. (c) 2012 Elsevier B.V. All rights reserved.