Particulate-bound aliphatic and polycyclic aromatic hydrocarbons (AHs and PAHs) were investigated in the surface waters of the Gulf of Gabès (Tunisia, southern Mediterranean Sea). Samples were collected off the Sfax and Gabès-Ghannouch coasts. Concentrations in total resolved n-alkanes ranged from 0.03 to 3.2 μg L−1, and concentrations in total parents + alkylated PAHs ranged from bdl to 108.6 ng L−1. The highest concentrations were recorded in the southern Sfax. AHs were mainly of biogenic origin with odd n-alkane predominance, although an anthropogenic contribution was also detected. The PAH molecular patterns revealed a mixed origin with the presence of low molecular weight and alkylated compounds, characteristic of uncombusted oil-derived products, and the presence of high molecular weight compounds, typical of combustion residues. Rainfall events induced an increase in PAH concentrations by a factor 1.5–23.5. The particle-water partition coefficients (Koc) suggest that the partitioning of PAHs between the particulate and dissolved phases is driven by hydrophobicity and organic matter composition.

The aim of this study was to assess, for the first time, the concentrations, sources, dry deposition and human health risks of polycyclic aromatic hydrocarbons (PAHs), aliphatic hydrocarbons (AHs), poly-chlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) in total suspended particle (TSP) samples collected in Bizerte city, Tunisia (North Africa), during one year (March 2015eJanuary 2016). Concentrations of PAHs, AHs, PCBs and OCPs ranged 0.5e17.8 ng m À3 , 6.7e126.5 ng m À3 , 0.3e11 pg m À3 and 0.2e3.6 pg m À3 , respectively, with higher levels of all contaminants measured in winter. A combined analysis revealed AHs originating from both biogenic and petrogenic sources, while diesel vehicle emissions were identified as dominant sources for PAHs. PCB potential sources included electronic, iron, cement, lubricant factories located within or outside Bizerte city. The dominant OCP congeners were p,p 0-DDT and p,p 0-DDE, reflecting a current or past use in agriculture. Health risk assessment showed that the lifetime excess cancer risk from exposure to airborne BaP was negligible in Bizerte, except in winter, where a potential risk to the local population may occur.

The spatio-temporal variability of fluorescent dissolvedorganic matter (FDOM) and its relationships withphysical (temperature, salinity) and chemical (nutrients, chlorophyll a, dissolved and particulate organic carbon, nitrogen and phosphorus) parameters were investigated in inland waters of the Rhône River delta and the Fos-Marseille marine area (northwestern Mediterranean, France). Samples were taken approximately twice per month in two inland sites and three marine sites from February 2011 to January 2012. FDOM was analysed using fluorescence excitation-emission matrices (EEMs) coupled with parallel factor analysis (PARAFAC). In inland waters, humic-like components C1 (λEx/λEm: 250 (330)/394 nm) and C3 (λEx/λEm: 250 (350)/ 454 nm) dominated over one tryptophan-like component C2 (λEx/λEm: 230 (280)/340 nm), reflecting a background contribution of terrigenous material (~67% of total fluorescence intensity, in quinine sulphate unit (QSU)) throughout the year. In marine waters, protein-like material, with tyrosine-like C4 (λEx/λEm: <220 (275)/<300 nm) and tryptophan-like C5 (λEx/ λEm: 230 (280)/342 nm), dominated (~71% of total fluorescence intensity, in QSU) over a single humic-like component C6 (λEx/λEm: 245 (300)/450 nm). In inland waters of the Rhône River delta, humic-like components C1 and C3 were more abundant in autumn-winter, very likely due to inputs of terrestrial organic matter from rainfalls, runoffs and windinducedsediment resuspension. In marine sites, intrusions ofthe Berre Lagoon and Rhône River waters had a significant impact on the local biogeochemistry, leading to higher fluorescence intensities of humic- and protein-like components in spring-summer. On average, the fluorescence intensities of FDOM components C4, C5 and C6 increased by 33–81% under lower salinity. This work highlights the complex dynamics of FDOM in coastal waters and confirms the link between marine FDOM and the Rhône River freshwater intrusions on larger spatial and temporal scales in the Fos-Marseille marine area.

We evaluated the relative impact of anthropogenicpolycyclic aromatic hydrocarbons (PAHs) among biogeochemicalvariables on total, metabolically active, and PAHbacterial communities in summer and winter in surfacemicrolayer (SML) and subsurface seawaters (SSW) acrossshort transects along the NW Mediterranean coast from threeharbors, one wastewater effluent, and one nearshore observatoryreference site. At both seasons, significant correlationswere found between dissolved total PAH concentrations andPAH-degrading bacteria that formed a gradient from the shoreto nearshore waters. Accumulation of PAH degraders wasparticularly high in the SML, where PAHs accumulated.Harbors and wastewater outfalls influenced drastically andin a different way the total and active bacterial communitystructure, but they only impacted the communities from thenearshore zone (<2 km from the shore). By using direct multivariatestatistical analysis, we confirmed the significant effectof PAH concentrations on the spatial and temporal dynamicof total and active communities in this area, but this effect was putted in perspective by the importance of otherbiogeochemical variables

The La Saline fringing reef, which is the most important coral reef complex of La Réunion Island, (southwestern Indian Ocean), is subjected to anthropogenic pressures through river and groundwater inputs. Salinity and biogeochemical parameters (silicates, nitrates, dissolved organic carbon, chlorophyll-a), as well as aliphatic hydrocarbons (AHs) and polycyclic aromatic hydrocarbons (PAHs) were analysed in particulate and dissolved material from groundwaters, rivers, harbour, back reef, fore reef and oceanic waters in the La Saline reef area during the rainy season (February–March 2012). Particulate and dissolved AH concentration ranges were 0.07–144 and 0.06–0.58 mg L-1 respectively. Particulate and dissolved PAH concentrations ranges were 4.3–326 and 28–350 ng L-1 respectively. AHs, dominated by nC15, nC17, nC18 compounds or nC26, nC27, nC29, nC31 compounds, were mainly of biogenic origin (phytoplankton, bacteria, higher-plant debris) although some anthropogenic (petroleum inputs) signatures were recorded in the dissolved phase from the harbour and fore reef areas. PAHs, dominated by two- to three-ring compounds and their alkylated homologues, reflected unburned petroleum inputs, but probably also biogenic sources. From the distribution of salinity, biogeochemical parameters and hydrocarbons, we found that inland waters flowed mainly in the surface and in the southern part of reef waters and that particulate PAHs allowed tracking these inland water intrusions in fore reef waters. Finally, this pilot study highlights the uncoupling between the dynamics of AHs and PAHs in tropical environments.

Polycyclic aromatic hydrocarbons (PAHs) and pesticides are among the most widespread organic contaminants in aquatic environments. Because of their aromatic structure, PAHs and pesticides have intrinsic fluorescence properties in the ultraviolet/blue spectral range. In this study, excitation-emission matrix (EEM) fluorescence spectroscopy and parallel factor (PARAFAC) analysis were used to characterise and discriminate fluorescence signatures of nine PAHs and three pesticides at the µg l-1 level in the presence of humic substances (0.1 to 10 mg C l-1). These contaminants displayed a diversity of fluorescence signatures regarding spectral position (λEx: 220-335 nm, λEm: 310-414 nm), Stokes shift (39-169 nm) and number of peaks (1-8), with detection limits ranging from 0.02 to 1.29 µg l-1. The EEM/PARAFAC method applied to mixtures of PAHs with humic substances validated a seven-component model that included one humic-like fluorophore and six PAH-like fluorophores. The EEM/PARAFAC method applied to mixtures of pesticides with humic substances validated a six-component model that included one humic-like fluorophore and three pesticide-like fluorophores. The EEM/PARAFAC method adequately quantified most of the contaminants for humic substance concentrations not exceeding 2.5 mg C l-1. The application of this method to natural (marine) samples was demonstrated through 1) the match between the Ex and Em spectra of PARAFAC components and the Ex and Em spectra of standard PAHs, and 2) the good linear correlations between the fluorescence intensities of PARAFAC components and the PAH concentrations determined by GC-MS.