| Abstract
| - Air and seawater samples were collected on board the RV Polarstern during a cruise from Bremerhaven, Germany to Cape Town, South Africa from October-November 2005. Broad latitudinal trends were observed with the lowest Σ27PCB air concentration (∼10 pg m−3) in the South Atlantic and the highest (∼1000 pg m−3) off the west coast of Africa. ΣICESPCBs ranged from 3.7 to 220 pg m−3 in air samples and from 0.071 to 1.7 pg L−1 in the dissolved phase seawater samples. Comparison with other data from cruises in the Atlantic Ocean since 1990 indicate little change in air concentrations over the remote open ocean. The relationship of gas-phase partial pressure with temperature was examined using the Clausius-Clapeyron equation; significant temperature dependencies were found for all PCBs over the South Atlantic, indicative of close air-water coupling. There was no temperature dependence for atmospheric PCBs over the North Atlantic, where concentrations were controlled by advection of contaminated air masses. Due to large uncertainties in the Henry’s Law Constant (HLC), fugacity fractions and air-water exchange fluxes were estimated using different HLCs reported in the literature. These suggest that conditions are close to air-water equilibrium for most of the ocean, but net deposition is dominating over volatilization in parts of the transect. Generally, the tri- and tetrachlorinated homologues dominated the total flux (>70%). Total PCB fluxes (28, 52, 118, 138, and 153) ranged from −7 to 0.02 ng m−2 day -1.
- The spatial and temporal trends and processes affecting the behavior of polychlorinated biphenyls (PCBs) in the Eastern Atlantic region.
|
