Fate of chiral and achiral organochlorine pesticides in the North Atlantic Bloom Experiment.
Organochlorine pesticides (OCPs) were measured in the surface seawater and lower atmosphere during the North Atlantic Bloom Experiment in the spring 2008 from samples collected on the R/V Knorr. The gaseous concentration profiles resulted from both long-range transport (LRT) from the Arctic by polar easterlies and local biogeochemical processes. Relatively constant α/γ-hexachlorocyclohexane (HCH) ratios and enantiomer fractions of α-HCH indicated that a single water mass was sampled throughout the cruise. Changes in dissolved phase concentrations were dominated by bloom processes (air-water exchange, partitioning to organic particles, and subsequent sinking) rather than LRT. α-HCH and dissolved phase trans-chlordanes showed depletion of (+) enantiomer, whereas depletion of the (-) enantiomer was observed for heptachlor exo-epoxide (HEPX) and cis-chlordanes. Fugacity ratio calculations suggest that hexachlorobenzene (HCB) and γ-HCH were depositing from air to water whereas heavier OCPs (chlordanes, HEPX) were evaporating. Dissolved phase concentrations did not decrease with time during the three-week bloom period; neither were lipophilic OCPs drawn down from air to water as previous studies hypothesized. Comparison with Arctic measurements suggested that the Arctic returned higher concentrations of α-HCH and HCB through both the atmospheric (polar easterlies) as well as oceanic transport (East Greenland Current) to the lower latitudes.
Graduate School of Oceanography, University of Rhode Island, Narragansett, Rhode Island 02882-1197, USA.
Lin
L
Zhang
Terry
T
Bidleman
Mary Jane
MJ
Perry
Rainer
R
Lohmann
D001110:Arctic Regions; D001267:Atlantic Ocean; D006843:Hydrocarbons, Chlorinated / Q000737:chemistry*; D010575:Pesticides / Q000737:chemistry*; D013237:Stereoisomerism
D006843:Hydrocarbons, Chlorinated; D010575:Pesticides