Evidence for Diffuse Contamination of River Sediments by Road Asphalt Particles

Abstract

Saturated hydrocarbons analysis was carried out on different river sediments from Alsace-Lorraine in order to detect possible contaminations by petroleum byproducts. The distributions of n-alkanes from all studied samples are very similar and are characterized by an odd-over-even carbon number predominance, underlining the higher plant contributions. On the other hand, pentacyclic triterpanes and steranes occur in all river sediments and display similar signatures that are characteristic of a mature organic matter contribution inherited from anthropogenic contamina tions. Among the different possible pollutants origins, point industrial sources seem unlikely because of the highly homogeneous biomarker signatures and the geographical repartition of the studied rivers. Because of the intense road traffic in Alsace-Lorraine, main vehicle fuels and exhausts have been investigated. Unleaded and diesel fuels, used engine oils, and engine exhausts cannot account for the biomarker distributions observed in river sediments. On the contrary, saturated hydrocarbons extracted from road asphalts are chiefly composed of polycyclic biomarkers with chromatographic signatures very close to those of river sediments. Moreover, microscopic investigations of river sediments allow us to identify asphalt particles and to confirm that the different rivers studied are contaminated by road asphalts. Such contaminations may distort biomarker signatures and GC−MS data and overprint the possible pollution by other petroleum byproducts.

A Technosol as archives of organic matter related to past industrial activities

“…Qualitative and quantitative analyses were conducted on the EOM by capillary gas chromatography coupled to mass spectrometry (GC-MS) to identify organic molecules, particularly biomarkers (Faure et al, 2000;Jeanneau et al, 2008a;2008b;Biache et al, 2011;Bertrand et al, 2012). For the qualitative series, dry extracts (500 µL of EOM) were solubilized in 250 µL of DCM and 250 µL of BSTFA (N, O bis(trimethylsilyl)trifluoroacetamide) and heated at 60°C during 15 min to activate the silylation, before being injected into a GC (Agilent Technology 6890 N) coupled to a MS (Agilent Technology 5973 Inert Mass Selective Detector).…”

“…Phytone (6,10,14-trimethylpentadecan-2-one) could originate from the degradation of phytol (ester-linked sidechain of chlorophyll-a) (Rontani and Volkman, 2003). However, the occurrence of compounds such as hopanes and PAHs indicated the contribution of anthropogenic OM in the surface layer (Faure et al, 2000;Peters et al, 2005). Sub-surface layers (2 and 3) were characterized by a specific n-alkanes distribution leading to CPI values higher than unity, a distribution of n-alkan-1-ols with even-over-odd predominance and sitosterol was also detected.…”

“…All along the profile, the contribution of anthropogenic OM was supported by the presence of PAHs and petrogenic biomarkers such as hopanes and iso-and cyclo-alkanes, reflected by the occurrence of an UCM. The distribution of stable configuration hopanes (17α,21β) is characteristic of thermal mature crude oil (Peters et al, 2005) or by-products, such as lubricant oils and greases and road asphalt (Faure et al, 2000;Jeanneau, 2007). Aromatic compound profiles showed the predominance of HMW parent PAHs with a low proportion of alkyl-PAHs which is typical of pyrogenic PAHs (Stout et al, 2004).…”

“…The biomarker approach is used to characterize organic contamination and its evolution in soils and sediments (e.g. Faure et al, 2000;Faure et al, 2007;Badin et al, 2008;Bloundi et al, 2008;Kèlomè et al, 2012). Radiocarbon analysis validated this quantitative multimolecular marker approach as an efficient tool to quantify fossil OM in contaminated river sediments (Jeanneau and Faure, 2010).…”

Organic Contaminants in Riverine and Groundwater Systems

“…Appropriate compounds are n-alkanes, steranes, hopanes and acyclic isoprenoids (e.g. Jovancicevic et al 1997;Jovancicevic et al 1998, Kaplan et al 1997Tran et al 1997;Volkmann et al 1997, Wehner et al 1998: Faure et al 2000Jovancicevic et al 2003 ).…”