St Georges Bay of Lebanon's coast is an open bay to the Mediterranean Sea. It is exposed to numerous anthropogenic activities such as industrial effluent, untreated wastewater discharge and maritime activities resulting in increasing chemical contamination, especially with trace metals. Contamination with trace metals (Cu, Cd, Co, Pb, As, Ag and Hg) and the influence of early diagenesis on their distribution were studied on both sediments and waters. For this purpose, sediment cores were collected, then treated under inert atmosphere to retrieve pore waters and solid fraction. The area appears to be seriously impacted by the materials transported by the Beirut River and/or by direct inputs, and recent land reclamation using dumpsite material. The sediments showed a significant level of contamination. Element mobility was studied by selective extraction on sediments. The mobility of trace elements from solid fraction to pore waters is controlled by the Fe/Mn cycle and organic matter.

Over the past decade, the distribution of harbour porpoises Phocoena phocoena has undergone a southward shift in the North Sea, which has led to an increase in the number of stranded porpoises in its southern part. Since the changes in distribution and relative abundance of porpoises may be linked to the changes in prey availability, the aim of the present work was to investigate whether any changes in the feeding habits of harbour porpoises along the North Sea occurred in the past decade. The diet of harbour porpoises stranded along the southern North Sea (northern France and Belgian coast) was assessed through 3 complementary methods: stomach content analysis, stable isotopes (carbon and nitrogen) analysis determined from muscle samples, and fatty acids analysis determined from blubber samples. Fatty acid patterns and stable isotope values from 52 porpoises were compared to 14 potential prey species collected from the southern North Sea. Our results showed that the diet of porpoises along the southern North Sea comprises fish species that are among the most abundant and widely distributed in the area, except for the sardine Sardina pilchardus that appeared to be a new potential prey. Moreover, our results suggested that the decline in sandeel (Ammodytidae) in the northern parts of the North Sea along with the re-invasion of the southern North Sea by sardine species might affect the distribution of harbour porpoises.

Mediterranean Sea (MS) is a semi-enclosed sea hosting a high population density and is exposed to numerous anthropogenic activities that contaminate the surrounding environment with pollutants such as trace metals (TM). TM distribution is influenced by numerous (bio) geochemical processes which can turn sediments into a secondary source of contaminants for the ecosystem. In this study, we investigate TM contamination in two coastal Mediterranean sites: Toulon Bay (Northwestern MS, France) and St-Georges Bay (Eastern MS, Lebanon). Both sites are submitted to anthropogenic pressures and host urbanized coastal rivers (Las River and Beirut River, respectively). Even, if Las River contribution is non-negligible for few elements but it contributes in dilution of past pollutions of the bay. In contrast, sediments from St-Georges Bay are impacted by several anthropogenic activities transported through Beirut River. Additionally, early diagenesis highly affects TM mobility in the sediments of these two ecosystems.

Abi-Ghanem Carine, Celine Mahfouz, Gaby Khalaf, Elie Najjar, Henri El-Zakhem and Rima Manneh. 2016. Pb, Cd and Cu distribution and mobility in marine sediments from two ports in Lebanon: Beirut army naval port and Tripoli fishing port. Lebanese Science Journal, 17(1): 59-75. Lead, cadmium and copper distribution and mobility in superficial sediments collected from the Beirut army navel port and Tripoli fishing port in Lebanon were studied. Results showed relatively high concentrations of Pb (181.4-518.9μg.g-1), Cd (1.33-6.7μg.g-1), and Cu (141-246.8μg.g-1) in sediments inside the port of Beirut. In Tripoli fishing port, Pb and Cd concentrations in sampled sediments were lower. However, higher Cu concentrations (up to 524.5 μg.g-1) were detected in Tripoli sediments. The extractability of Cd, Pb and Cu from the sediments of Beirut and Tripoli port were studied by applying EDTA 0.05M and CaCl2 0.01M extractions for two extraction times: 1h and 24h. These extractions showed that Cd and Pb were highly mobilized by EDTA. However, only Pb was mobilized by CaCl2 from sediments collected in Beirut military port.

Mercury (Hg) contamination in coastal sediments has been widely studied in clay deposits; however, equivalent results on carbonated sediments are scarce. This article aims to study Hg distribution in Lebanese carbonate coastal marine sediments (Eastern Mediterranean) in order to characterize their contamination level and to explore the postdepositional mobility of methylmercury (MeHg) in the deposits. Vertical distribution profiles of total (HgT) and MeHg have been established for the solid phase of sediment cores collected in various near-shore environments chosen for their hypothetical various degrees of anthropization. In addition, dissolved MeHg was determined in sediment pore waters to test its mobility and potential availability for biota. Three sites on the Lebanese coasts—Akkar, Dora, and Selaata—were selected. Akkar is far from any direct contamination source, whereas Dora, located near the Beirut harbor, is a heavily urbanized and industrialized zone including a huge dump site, and Selaata is near a chemical plant that produces phosphate fertilizers. Particulate HgT concentrations in the sediments varied between <0.04 and 0.65 μg/g, with a proportion of MeHg lower than 1%. Based on a sediment quality guideline (MacDonald et al. 2000), we concluded that Dora bay sediments are heavily contaminated by Hg, with concentrations exceeding the “consensus-based threshold effect” level (0.17 μg/g) and almost reaching the “effects range-medium” level (0.71 μg/g). In spite of the low HgT concentration in Akkar and Selaata sediment (similar to natural carbonated sediment: 0.04 μg/g according to Turekian and Wedephol (1961), a closer analysis of the sediment core vertical profile allows one to observe an anthropogenic impact. This impact might be toxicologically insignificant; however, it allows tracing the time increase of Hg diffuse deposition. On the other hand, dissolved MeHg concentrations ranged from 0.04 to 0.09 and from 0.04 to 8.76 ng/l in the Selaata and the Dora sediments, respectively; MeHg vertical profiles in interstitial water enabled us to calculate diffusive fluxes of MeHg from the sediment varying from 0.3 to 1.0 ng/m2/day. Thus, the deposited sediments constitute a measurable source of bioavailable Hg for epibenthic organisms.

Cd and Pb extractability with EDTA were measured from sediment samples collected at three contrasted sites along the Lebanese coastal zones: Akkar, Dora and Selaata. Akkar is located away from any direct source of contamination, while Dora and Selaata receive respectively urban and industrial wastes. The extractability of Cd and Pb from sediments of the aforementioned sites was studied by applying kinetic and equilibrium extractions with EDTA 0.05M. The adjustment of Pb kinetic extractions curves to a two-first order reactions model permitted to kinetically fractionate Pb in the studied sediments into three fractions (readily extractable, less extractable and non extractable) and allowed to conclude that Pb in Selaata represents the highest environmental risk.