Atmospheric PCB Concentrations at Terra Nova Bay, Antarctica ANDREA GAMBARO,* ,†,‡ LAURA MANODORI, † ROBERTA ZANGRANDO, ‡ ALESSANDRA CINCINELLI, § GABRIELE CAPODAGLIO, †,‡ AND PAOLO CESCON †,‡ Environmental Sciences Department, Ca’ Foscari University of Venice, 30123 Venice, Italy, Institute for the Dynamics of Environmental Processes, C.N.R., 30123 Venice, Italy, and Department of Chemistry, University of Florence, 50019 Florence, Italy Concentrations of gas-phase polychlorobiphenyls (PCBs) were studied over an austral summer at a site in Terra Nova Bay, Antarctica. Gas-phase concentrations of individual PCB congeners in the atmosphere of Terra Nova Bay ranged from below the detection limit to 0.25 pg m -3 , with a mean concentration of ∑PCB of 1.06 pg m -3 . The PCB profile was dominated by lower-chlorinated PCB congeners; in fact >78% of the total PCB content was due to congeners with 1-4 chlorine atoms and only about 10% with 5-7 chlorines, whereas higher-chlorinated PCB congeners were below detection limits. The mean ∑PCB concentration obtained in this study were lower than those reported in previous Antarctic studies. Temporal concen- tration profiles of ∑PCB do not correspond to seasonal temperature changes. In consideration of the low PCB concentrations observed, the studies with the wind roses, the regression between ln P(PCB) and T -1 , and the distribution of congeners, we can hypothesize that PCB local source contributions are not very important, whereas long-distance transport is the prevalent factor bringing PCBs to Terra Nova Bay. Introduction Polychlorobiphenyls (PCBs) are a class of nonpolar semi- volatile organic compounds which includes 209 congeners divided into 10 homologue classes. They are chemically very stable, persistent in the environment, and toxic with endo- crine-disrupting properties, and they bio-accumulate in the food chain. For all these reasons, they are generally con- sidered priority pollutants, thus making their monitoring in the environment and studies of their toxic effects on living organisms of prime importance. Long-range atmospheric transport can move PCBs away from source regions to more remote and pristine locations such as Antarctica, which has made PCBs ubiquitous in the global environment. Montone et al. (1) reported that comparable levels of contamination in seawater from north and south of the Antarctic Conver- gence indicated that the atmosphere, not the water, was the dominant pathway for the transport of PCB compounds to the Antarctic. Further evidence of atmospheric transport of PCBs in the Antarctic environment was provided by Fuoco et al. (2) whose studies of Antarctic lake sediment found high contributions of atmospheric particulate matter as the primary vehicle of transport and diffusion of PCBs in the environment. In addition to atmospheric transport, local sources of PCBs, such as Antarctic Research Stations, should be considered (3). Finally, information on the impact of long- range transport and local sources can be obtained from an analysis of the PCB concentration in surface snow. The deposition and accumulation of PCBs in the Antarctic snow/ pack ice are, in fact, considered to be important steps in their transfer from the atmosphere to terrestrial and marine systems (4). In Antarctica, the presence of contaminants can threaten living resources since several persistent organic pollutants (POPs), including PCBs, accumulate in the tissues of organ- isms (4, 5). PCBs have also been detected in Arctic biota. In general, because they originated mainly in the Northern hemisphere, their levels were lower in the Antarctic biota than in Arctic biota. Data concerning concentrations of PCBs in Antarctic air are very scarce. They were mainly collected during cruises such as the Atlantic cruise from the United Kingdom to Halley, Antarctica (6), with the aim of establishing PCB oceanic background air concentrations and assessing their latitudinal distribution, and from a few sampling campaigns on the continent itself. Kallenborn et al. (7) measured PCBs in ambient air at Signy Island over a period of 17 weeks and found that mean concentrations for single congeners were comparable to those in Arctic air. Montone et al. (1) report that atmospheric levels of PCBs in the vicinity of the Brazilian Antarctic Research Station were generally low and the higher levels were associated with the passage of the frontal system coming from South Africa. Moreover Ockenden et al. (8) monitored the air for PCBs at two sites in the southern hemisphere, one over land and the other over water. They found that the highest concentrations were observed when temperatures were greater and the air concentrations were higher over water than over land. In this study we increase the limited atmospheric database on PCBs in remote areas by reporting PCB concentrations during the austral summer at a site in Terra Nova Bay, Antarctica, and we hypothesize their possible sources. Experimental Section Sampling and Analysis. Air samples were collected at a coastal site off the Northern Victoria Land (Figure 1), about 3 km south of the Italian base of Terra Nova Bay (74° 42′ 56.3′′ S, 164° 06′ 52′′ E), during the austral summer between 4 November 2003 and 30 January 2004 (XIX Italian Antarctic Expedition). Sampling was performed over a 5-day period, providing a total of nine observations. Samples were obtained using high volume samplers (Tisch Environmental Inc., Cleves, OH) equipped with a quartz fiber filter (QFF; size 102 mm, SKC) and a polyurethane foam plug (PUF; height 75 mm, diameter 65 mm, SKC, Eighty Four, PA) to differentiate the particulate and the gas phases, respectively. Filters were not analyzed because no significant retention of PCB congeners was observed during our preliminary tests, as reported by other authors (1, 8). This is in contrast with the fact that the condensation and deposition of gas-phase samples at such low temperatures in Antarctica should be significant. Strip- ping processes from the filters, caused by the high operative flow (average: 0.34 m 3 min -1 ) and the high volume of air * Corresponding author fax: +39-41-2348549; e-mail: gambaro@ unive.it. † Ca’ Foscari University of Venice. ‡ Institute for the Dynamics of Environmental Processes. § University of Florence. Environ. Sci. Technol. 2005, 39, 9406-9411 9406 9 ENVIRONMENTAL SCIENCE & TECHNOLOGY / VOL. 39, NO. 24, 2005 10.1021/es0510921 CCC: $30.25  2005 American Chemical Society Published on Web 11/04/2005