Historical input and behaviour of hexachlorobenzene, polychlorinated biphenyls and polycyclic aromatic hydrocarbons in two dated sediment cores from the Scheldt estuary, SW Netherlands
van Zoest, R.; van Eck, G.Th.M. (1993). Historical input and behaviour of hexachlorobenzene, polychlorinated biphenyls and polycyclic aromatic hydrocarbons in two dated sediment cores from the Scheldt estuary, SW Netherlands. Mar. Chem. 44(1): 95-103. http://dx.doi.org/10.1016/0304-4203(93)90008-C
Hexachlorobenzene (HCB), individual polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) were measured in the less than 63 µm fraction of two dated sediment cores from the salt marshes of the Scheldt estuary, S.W. Netherlands, in order to determine their historical input and post-depositional behaviour.
The recent input of PCBs and PAHs (e.g. 80–280 µg m−2 a−1 for PCB 153 and 2–7 mg m−2 a−1 for fluoranthene) was two to three times lower than the maximum input in the mid 1960s. The peak discharge of HCB was recorded around 1972. Contents of organic micropollutants in one core were twice as high as in the other one, although both sites had approximately the same distance to the main pollution source. A high percentage of particles less than 20 µm, probably of marine origin with relatively low pollutant contents in one core, were presumably responsible for this difference.
The PCB profiles show post-depositional congener-selective mobilization caused by advective transport (tailing). The PCB pattern changes, between 1965 and 1975, from less chlorinated to more heavily chlorinated PCBs. This shift coincides with the decrease in the use of PCBs in open systems.
Unlike PCBs, the PAH assemblage is remarkably uniform within a core and between the cores. The PAH ratios indicate that the combustion of coal was the source of PAHs in the Scheldt estuary.
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