Air-water distribution of hexachlorobenzene and 4,4’‑DDE along a North-South Atlantic transect.

Concentration data for organic contaminants in remote areas are scarce, particularly for open ocean systems. These data are much needed for the global fate assessment of these compounds, both for water and air. The traditional methods for determining these concentrations, such as high-volume air and water sampling with polyurethane foam or XAD are labour-intensive and – in the case of batch water sampling – require much station time at sea, which makes these methods costly as well. Passive sampling methods like semipermeable membrane devices (SPMDs, [Huckins et al., 1990] and [Huckins et al., 2006]) have been used as an alternative to the high-volume extraction methods in air ([Ockenden et al., 1998], [Lohmann et al., 2001] and [Meijer et al., 2003]) and in water (Crunkilton and DeVita, 1997 R.L. Crunkilton and W.M. DeVita, Determination of aqueous concentrations of polycyclic aromatic hydrocarbons (PAHs) in an urban stream, Chemosphere 35 (1997), pp. 1447–1463. Article | PDF (739 K) | View Record in Scopus | Cited By in Scopus (23)[Crunkilton and DeVita, 1997], [Luellen and Shea, 2002] and [Verweij et al., 2004]). A ship-based deployment of these samplers during transit time could yield valuable concentration data with little effort and at low cost. However, the sampling rates of SPMDs are in the range 1–20 m3 d−1 for air, and 1–200 L d−1 for water, depending on the physicochemical properties of the analytes and on the exposure temperature and flow velocity (Huckins et al., 2006). The very low concentrations in open ocean systems combined with potentially low sampling rates could result in detectability problems. The detectability could be improved by extending the exposure time, albeit with a loss of spatial resolution in the case of a ship in transit. To assess the merits of ship-based organic contaminant monitoring with passive samplers, we did a pilot study on board the RV Pelagia, in its transit from the island of Texel (The Netherlands) to Walvis Bay (Namibia) and Cape Town (South Africa), targeting polychlorinated biphenyls (PCBs), hexachlorobenzene (HCB), 1,1-dichloro-2,2-bis(4-chlorophenyl)ethene (4,4′-DDE), and polyaromatic hydrocarbons (PAHs)