Evolution of the source apportionment of the lipidic fraction from sediments along the Fensch River, France: A multimolecular approach

The Fensch River (FR) is one of the most contaminated rivers in France due to the population density and the concentration of industrial activities in this small watershed area. From upstream to downstream, the organic matter extracted from sediments has been analyzed by gas chromatography–mass spectrometry and molecules have been quantified and classified into natural, petrogenic, pyrogenic and sewage water (SW) markers. Upstream the river, anthropogenic molecules are already predominant and represent 87.1% of the molecules quantified. This proportion increases from upstream to downstream and rises to 96.8% at the confluence of the FR with the Moselle River. In the upper part of the FR the contamination is mainly due to human waste (coprostanol: 36.44 µg/g; 42.1% of anthropogenic markers). In the lower part, the contribution of SW markers decreases from 42.1 to 2.4% and the proportion of pyrogenic molecules increases from 29.6 to 59.6%. The major sources of pyrogenic organic matter have been determined by calculation of specific ratios on polycyclic aromatic hydrocarbons and by comparison with reported data. Coal tar, road runoff and atmospheric depositions of urban particles seem to be the major pyrogenic sources. Along the river, the proportion of petrogenic molecules remains constant and those molecules seem to be mainly inherited from road runoff, in the upper part of the FR. Industrial lubricants that occur in steel plant sludge are an additional source in the lower part of the river.