Biogeochemical and physical controls on concentrations of polycyclic aromatic hydrocarbons in water and plankton of the Mediterranean and Black Seas

Abstract

[1] The Mediterranean and Black Seas are unique marine environments subject to important anthropogenic pressures due to atmospheric and riverine inputs of organic pollutants. They include regions of different physical and trophic characteristics, which allow the studying of the controls on pollutant occurrence and fate under different conditions in terms of particles, plankton biomass, interactions with the atmosphere, biodegradation, and their dependence on the pollutant physical chemical properties. Polycyclic Aromatic Hydrocarbons (PAHs) have been measured in samples of seawater (dissolved and particulate phases) and plankton during two east-west sampling cruises in June 2006 and May 2007. The concentrations of dissolved PAHs were higher in the south-western Black Sea and Eastern Mediterranean than in the Western Mediterranean, reflecting different pollutant loads, trophic conditions and cycling. Particle and plankton phase PAH concentrations were higher when lower concentrations of suspended particles and biomass occurred, with apparent differences due to the PAH physical chemical properties. The surface PAH particle phase concentrations decreased when the total suspended particles (TSP) increased for the higher molecular weight (MW) compounds, consistent with controls due to particle settling depletion of water column compounds and dilution. Conversely, PAH concentrations in plankton decreased at higher biomass only for the low MW PAHs, suggesting that biodegradative processes in the water column are a major driver of their occurrence in the photic zone. The results presented here are the most extensive data set available for the Mediterranean Sea and provide clear evidence of the important physical and biological controls on PAH occurrence and cycling in oceanic regions.

Macondo‐1 well oil‐derived polycyclic aromatic hydrocarbons in mesozooplankton from the northern Gulf of Mexico

“…Several processes (e.g. exchange with water through passive partitioning, ingestion of contaminated food, and production of fecal pellets and eggs), occurring simultaneously, may affect the final body burden of PAHs derived from oil spills [Sobek et al, 2006;Berrojalbiz et al, 2011]. Moreover, all of these processes may vary as a function of ambient temperature and seasonality [Hallanger et al, 2011b].…”

Occurrence, sources and transport pathways of natural and anthropogenic hydrocarbons in deep-sea sediments of the eastern Mediterranean Sea

“…Unlike PAHs of pyrolytic origin, these compounds enter the water column mainly through air-water diffusive exchange (Castro-Jiménez et al, 2012) or are directly introduced into surface waters following the release of petroleum products (Wang et al, 1999). Direct and indirect evidence of biodegradation has been suggested as an important factor affecting low-MW PAHs' abundance during transport in the water column (Berrojalbiz et al, 2009(Berrojalbiz et al, , 2011. Indeed, atmospheric inputs of phenanthrenes in the Mediterranean Sea are reported to be two orders of magnitude higher than settling fluxes (Castro-Jiménez et al, 2012;Dachs et al, 1997;Deyme et al, 2011;Tsapakis et al, 2006).…”

A New Glider-Compatible Optical Sensor for Dissolved Organic Matter Measurements: Test Case from the NW Mediterranean Sea

“…These are in the same range than the concentrations of dissolved Phe (non-methylated + methylated) determined by GC-MS in the open Mediterranean Sea (0.4-4 ng L −1 ; Berrojalbiz et al, 2011) and in the coastal Mediterranean Sea (i.e., Bay of Marseille, 5-50 ng L −1 ; Guigue et al, 2011Guigue et al, , 2014.…”

“…A recent study estimated an atmospheric input of PAH in the ocean of about 0.09 Tg per month, equivalent to ∼15% of the oceanic CO 2 uptake (González-Gaya et al, 2016). Measurements of dissolved PAHs in the Mediterranean basin is specially of interest, since only few studies have focused on their distribution in this semienclosed and highly populated basin (Berrojalbiz et al, 2011;Guigue et al, 2011Guigue et al, , 2014. To the best of our knowledge, this study presents the first glider observations of these DOM fluorophores.…”

“…One of the most extensive study reporting PAHs concentrations in Mediterranean waters (Berrojalbiz et al, 2011) confirms that Phe and its alkylated (methylated) homologs were the predominant PAHs in water samples (dissolved and particulate) and in plankton biomass. However, most of the water samples used in this study were taken from the surface, where concentrations are rather low compare to the subsurface.…”