Sources of PCDD/Fs, non-ortho PCBs and PAHs in sediments of high and low impacted transboundary rivers (Belgium–France)

PAHs, PCDD/Fs and non-ortho PCBs have been assessed in Yser and Upper-Scheldt river sediments. Higher contamination levels were observed in the Upper-Scheldt sediments: maximum concentrations for the 16 US-EPA PAHs, PCDD/Fs and non-ortho PCBs respectively amount to 8.9 mg kg−1, 12 ng TEQ kg−1 and 5.1 ng TEQ kg−1. Diagnostic PAH ratios in sediments and atmospheric samples suggest that the PAH compounds are from pyrolytic origin, more specifically combustion processes. The huge consumption of coal in cokes-ovens and smelters and its use for house-heating in Northern France, although decreasing during the last decades, are in support of that suggestion. PCDD/F fingerprints in sediments and deposition material indicate that OCDD is the dominant congener. In addition use of pentachlorophenol (PCP) in the past led to a minor contribution of PCDD/Fs in our sediment samples. Non-ortho PCBs form a substantial fraction of the total TEQ concentrations observed in the sediments. Since the 1980s and 1990s a substantial reduction of the PCDD/F sediment concentrations is observed, but this is not the case for the PAHs.

► Assessment of PAH, PCDD/Fs and dioxin-like PCBs in river sediments.
► Congener profiles are similar in the high and low impacted river.
► Main sources of PAHs are coal combustion (historically) and vehicular emissions (recently).
► The main source of PCDD/Fs is combustion, while pentachlorophenol is a minor source.
► High PCB-126 levels were linked to shredder installation emissions.