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.
Highlights
Anthropogenic chemicals, which are persistent and resist degradation in the environment, pose a long-term hazard for ecosystems on a large spatial scale
Complementary to the seawatermonitoring programme, this study investigated the spatial and seasonal distribution of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) in the marine atmosphere in 2009 and 2010 in order to assess their cycling in the North Sea region, to verify long-term trends and to advance knowledge of the contribution of atmospheric deposition to surface seawater contamination
Seasonal variations of organics in air were investigated by means of PUF disc passive air sampling (PAS; Klánová et al 2006; Yusà et al 2009) at a residential land based sampling site (Hamburg-Sülldorf, ≈100 km from the North Sea coast) and at a rural coastal sampling site (Tinnum/Sylt) between October 2009 and December 2010
Summary
Anthropogenic chemicals, which are persistent and resist degradation in the environment, pose a long-term hazard for ecosystems on a large spatial scale (i.e. far beyond the area of initial release). For semi-volatile substances (i.e. those with a vapour pressure over the subcooled liquid in the range 10−6– 10−2 Pa at 20 °C), the long-range atmospheric transport is enhanced by the multi-hopping potential (subsequent cycles of atmospheric transport, deposition and re-volatilisation from land or sea surfaces; grasshopper effect; Gouin et al 2004; Semeena and Lammel 2005) and their spatial range is often even global (Wania and Mackay 1993; Leip and Lammel 2004). POP cycling in shelf seas includes transport by winds and sea currents, atmospheric deposition and re-volatilisation from surface seawater, sinking and re-suspension with suspended particulate matter (SPM), phase partitioning in air (aerosol particles) and seawater (SPM), alongside other processes This is connected to the carbon cycle (Bidleman and McConnell 1995; Lohmann et al 2007; O’Driscoll et al 2013)
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