Particulate Fluxes of Aliphatic and Aromatic Hydrocarbons in Near-shore Waters to the Northwestern Mediterranean Sea, and the Effect of Continental Runoff

• Published in: Estuarine, coastal and shelf science Vol. 48; no. 5; pp. 605 - 616
• Main Authors: Raoux, C, Boyona, J.M, Miquel, J.-C, Teyssie, J.-L, Fowler, S.W, Albaigés, J
• Format: Journal Article
• Language: English
• Published: London Elsevier Ltd 01-05-1999; Elsevier
• Subjects: continental runoff; Earth, ocean, space; Exact sciences and technology; External geophysics; fecal pellets; hydrocarbon source identification; Marine; Mediterranean Sea; Physical and chemical properties of sea water; Physics of the oceans; POC; seasonal variability; sediment trap; sinking particles; vertical flux measurement; Mediterranean Sea; West Mediterranean; MED, Monaco; sediment trap; fecal pellets; POC; continental runoff; seasonal variability; vertical flux measurement; hydrocarbon source identification; sinking particles; Particle flux; Runoff; Seasonal variation; Chemical composition; Coastal water; Polycyclic aromatic compound; Principal component analysis
• ISSN: 0272-7714; 1096-0015
• DOI: 10.1006/ecss.1998.0458

Particulate fluxes of aliphatic and aromatic hydrocarbons were measured with a sediment trap moored at 80m depth offshore Monaco (200m water column) during an 18-month period. The highest fluxes of n -alkanes and polycyclic aromatic hydrocarbons (PAH) (c . 300 and 10μg m−2day−1, respectively) were noted following a strong rainfall event (March–April 1989) and were mostly accounted for by continental runoff and river outflows. Fluxes during periods of low precipitation (August 1989–August 1990) were one order of magnitude lower for PAHs (1·51±1·40μg m−2day−1) or two orders of magnitude lower for n -alkanes (4·79±3·3μg m−2day−1) than during the earlier period (March–April 1989). The total PAH and total particle fluxes exhibited a positive linear correlation during the entire sampling period (r =0·87, N =31, P< 0·05) underscoring the strong affinity of PAHs for particles. Examination of the seasonal variability of fecal pellet content, associated parameters (total organic carbon, total carbon, nitrogen), and individual hydrocarbon content of particles by Principal Component Analysis (PCA) showed that aliphatic and aromatic hydrocarbons were clustered in several subgroups in the PCA loading plots according to their origin. n -Alkanes were grouped in two clusters: (i) lower molecular weight (n -C16–19) and (ii) the higher molecular weight alkanes (n -C20–38) suggesting different pathways into the coastal zone (i.e. runoff vs atmospheric deposition). The distribution of lycopane, pristane and phytane indicated multiple origins. However, the closer location of the two isoprenoids, lycopane and pristane to fecal pellets, suggests a zooplanktonic origin but phytane to fossil fuel source. PAHs exhibited a variety of pyrolytic sources and only fluoranthene and pyrene were not grouped with the remaining PAHs suggesting multiple sources of pollution in these waters.