Persistent organochlorine pesticides and polychlorinated biphenyls in air of the North Sea region and air-sea exchange

Abstract

Organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) were studied to determine occurrence, levels and spatial distribution in the marine atmosphere and surface seawater during cruises in the German Bight and the wider North Sea in spring and summer 2009–2010. In general, the concentrations found in air are similar to, or below, the levels at coastal or near-coastal sites in Europe. Hexachlorobenzene and α-hexachlorocyclohexane (α-HCH) were close to phase equilibrium, whereas net atmospheric deposition was observed for γ-HCH. The results suggest that declining trends of HCH in seawater have been continuing for γ-HCH but have somewhat levelled off for α-HCH. Dieldrin displayed a close to phase equilibrium in nearly all the sampling sites, except in the central southwestern part of the North Sea. Here atmospheric deposition dominates the air-sea exchange. This region, close to the English coast, showed remarkably increased surface seawater concentrations. This observation depended neither on riverine input nor on the elevated abundances of dieldrin in the air masses of central England. A net depositional flux of p,p′-DDE into the North Sea was indicated by both its abundance in the marine atmosphere and the changes in metabolite pattern observed in the surface water from the coast towards the open sea. The long-term trends show that the atmospheric concentrations of DDT and its metabolites are not declining. Riverine input is a major source of PCBs in the German Bight and the wider North Sea. Atmospheric deposition of the lower molecular weight PCBs (PCB28 and PCB52) was indicated as a major source for surface seawater pollution.Electronic supplementary materialThe online version of this article (doi:10.1007/s11356-016-7530-3) contains supplementary material, which is available to authorized users.

Understanding the Role of Organic Matter Cycling for the Spatio-Temporal Structure of PCBs in the North Sea

“…In the offshore areas and the central North Sea, in contrast, were surface concentrations below a few pg L −1 . Our predictions were also consistent with results from [69] that showed concentrations of PCBs (sum of seven major congeners) typically ranging between less than 1 and 20 pg L −1 , with the higher levels occurring in the proximity of the German Bight and major river estuaries.…”

PCB residues in the tissues of sea ducks wintering on the south coast of the Baltic Sea, Poland

“…The differences observed between basins result mainly from the global distillation of PCBs: low-chlorinated congeners volatilize in warm regions and are transported to colder ones, while highly chlorinated compounds remain closer to the sources of emission (Wania and Mackay 1996 ). This has been confirmed by Mai et al ( 2016 ) which reported that while higher-chlorinated PCBs have been found to be present in the air near the shoreline, more volatile congeners tend to be observed in the open waters far from shore. Significant roles are also played by the concentration of point sources of PCB emission along the shoreline of the water body.…”

Spatial Distributions and Seasonal Changes of Current‐Use Pesticides from the North Pacific to the Arctic Oceans

“…Additionally, the polar regions, where agricultural activities are far away, may also receive significant quantities of CUPs released by sea ice melt in summer (Ma et al, 2011). Similar to the behaviors through atmospheric transport, distributions of CUPs in seawater are dynamic and changeable during transportation by ocean currents (Hargrave et al, 1997), with concentrations decreasing over time and distance (Mai et al, 2016) in accordance with microbial activities in water and CUPs' environmental persistence (as characterized by half-lives).…”