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Offshore fish farms have been active inside the Monastir Bay, Hammemet Gulf for over 10 years, but their environmental impact is still unknown. This study focuses on the evaluation of the fish farming activity impact in the Monastir Bay as revealed by geochemical and benthic foraminiferal data. Samples were collected around three fish cages at different water depths. Total organic carbon (TOC) and total phosphate (TP) in the sediment show higher values beneath the fish cages and decrease proportionally with distance from the cages. Living foraminiferal assemblages around fish farms are dominated by stress-tolerant species with higher abundances of Ammonia tepida , Rosalina bradyi , Elphidium crispum , and Peneroplis planatus . On the basis of our results, A. tepida and Quinqueloculina seminula are confirmed to be tolerant to elevated nutriment content, while Ammonia parkinsoniana seems to be more sensitive to organic enrichment. We also test the Foram-AMBI that is revealed to be a very promising tool by which evaluating the ecological quality status of marine sediment. The results of the present study confirm the suitability of living benthic foraminifera as bioindicators of organic enrichment induced by aquaculture activities.

Background Sfax is a very industrialized city located in the southern region of Tunisia where heavy metals (HMs) pollution is now an established matter of fact. The health of its residents mainly those engaged in industrial metals-based activities is under threat. Indeed, such workers are being exposed to a variety of HMs mixtures, and this exposure has cumulative properties. Whereas current HMs exposure assessment is mainly carried out using direct air monitoring approaches, the present study aims to assess health risks associated with chronic occupational exposure to HMs in industry, using a modeling approach that will be validated later on. Methods To this end, two questionnaires were used. The first was an identification/descriptive questionnaire aimed at identifying, for each company: the specific activities, materials used, manufactured products and number of employees exposed. The second related to the job-task of the exposed persons, workplace characteristics (dimensions, ventilation, etc.), type of metals and emission configuration in space and time. Indoor air HMs concentrations were predicted, based on the mathematical models generally used to estimate occupational exposure to volatile substances (such as solvents). Later on, and in order to validate the adopted model, air monitoring will be carried out, as well as some biological monitoring aimed at assessing HMs excretion in the urine of workers volunteering to participate. Lastly, an interaction-based hazard index HI int and a decision support tool will be used to predict the cumulative risk assessment for HMs mixtures. Discussion One hundred sixty-one persons working in the 5 participating companies have been identified. Of these, 110 are directly engaged with HMs in the course of the manufacturing process. This model-based prediction of occupational exposure represents an alternative tool that is both time-saving and cost-effective in comparison with direct air monitoring approaches. Following validation of the different models according to job processes, via comparison with direct measurements and exploration of correlations with biological monitoring, these estimates will allow a cumulative risk characterization.

Toxicity caused by exposure to pollutants from marine sediments is a consequence of the interaction between biota and xenobiotics most frequently released by anthropogenic activities. The present work intended to characterize the toxicity of natural sediments putatively impacted by distinct human activities, collected at several sites located in the south of the Gulf of Gabes, Zarzis area, Tunisia. The selected toxicity criteria were analysed following ecologically relevant test conditions. Organisms of the polychaete species Hediste diversicolor were chronically exposed (28 days) to the mentioned sediments. Toxicity endpoints were biomarkers involved in the toxic response to common anthropogenic chemicals, namely neurotoxic (acetylcholinesterase), anti-oxidant (catalase, glutathione peroxidase), metabolic (glutathione S-transferases) enzymatic activities, and oxidative damage (lipid peroxidation, TBARS assay). The chemical characterization of sediments showed that the samples collected from the site near an aquaculture facility were highly contaminated by heavy metals (Cd, Cu, Cr, Hg, Pb, and Zn) and polycyclic aromatic hydrocarbons (fluorene, phenanthrene, anthracene, fluoranthene and pyrene). H. diversicolor individuals exposed to the sediments from this specific site showed the highest values among all tested biomarkers, suggesting that these organisms were possibly under a pro-oxidative stress condition potentially promoted by anthropogenic pollution. Moreover, it was possible to conclude that individuals of the polychaete species H. diversicolor responded to the chronic exposure to potentially contaminated sediments from the southeast coast of Tunisia, eliciting adaptive responses of significant biological meaning.

Several irrigated agricultural perimeters have been established as a part of Tunisian strategy for optimizing the conservation of freshwater and providing alternative water sources. In this work, olive trees were cultivated in a small scale, irrigated with treated wastewater (TWW) from three different industrial wastewater treatment stations and compared with tap water used as a control (GW). In order to evaluate the performance of using effluents characterized by its high metal contents for the irrigation of agricultural crops with high added value, two-year monitoring of soil and plants characteristics was conducted by the evaluation of different physicochemical parameters such as plant growth and soil salts and metal contents. The increase of nutrients such as potassium, nitrogen, phosphorus and sodium was registered in soil after the application of different TWWs compared to the GW. The metal contents in both soil and plants increased but without exceeding the permissible limits. No significant differences in plant growth for all irrigation sources as demonstrated by investigated plant height. The absence of E. coli, Streptococcus and Total coliform in TWWs verified the safe microbial aspect on future olive fruits. Results based on the evaluation of different physicochemical properties of soil, plants growth and characteristics suggest the possibility of a brief reuse of TWWs in the irrigation of the olive tree.

Coastal marine areas are highly vulnerable to the exposure to various types of stressors and impact of chemical pollution resulting from increasing anthropogenic activities, namely pollution by metals and polycyclic aromatic hydrocarbons (PAHs). To assess ecosystem quality and functions, biomarkers can provide information about the presence and adverse effects of pollutants. Accordingly, the present study was conducted to evaluate the chronic (28 days) biologic effects of putatively contaminated sediments from the Zarzis area, located in the south of the Gulf of Gabes on the Southern Tunisian coast, on the marine flatfish Solea senegalensis. Sediments were collected at three sampling sites, impacted by wastewater discharges, aquaculture activities, and industrial contamination, and then surveyed for metals (Cd, Cu, Cr, Hg, Zn, and Pb) and organic contaminants (polycyclic aromatic hydrocarbons). The quantified biomarkers involved the determination of oxidative stress, phase II metabolism, and the extent of lipid peroxidation (catalase, CAT; glutathione peroxidase activity: total and selenium-dependent, T-GPx and Se-GPx; activities of glutathione-S-transferases, GSTs; levels of lipid peroxidation, by means of the thiobarbituric acid reactive substances assay, TBARS) and neurotoxicity (activity of acetylcholinesterase, AChE). S. senegalensis exposed to potentially contaminated sediments, collected near the aquaculture facility, presented the highest values for the generality of biomarkers tested, and a significant inhibition of AChE activity. A few lesions have been also recorded in the gills and liver tissues of S. senegalensis following chronic exposure. However, the observed lesions in gills (e.g., epithelial lifting, lamellar fusion, gills hyperplasia and hypertrophy, and leukocyte infiltration) and liver (cytoplasmic vacuolation, enlargement of sinusoids, foci of necrosis, and eosinophilic bodies) were of minimal pathological importance and/or low prevalence that did not significantly affect the weighted histopathological indices. Finally, the biological responses evidenced by this flatfish can be potentially caused by metal and PAH pollution occurring in specific areas in the southeast of Tunisia. The type and extent of the observed biochemical alterations strongly suggest that the contaminated sediments from the surveyed areas could cause early adverse biological effects on exposed biota.

A study of chemical and sedimentological parameters integrated with benthic foraminifera investigation was conducted along the northern coast of Gabes Gulf. Thirty-two samples were studied and a total of 68 benthic foraminiferal species were identified. Heavy metals enrichment factors and total hydrocarbon concentrations showed both metal and petrogenic pollution related mainly to phosphogypsum, sewage, and fishing activities. Statistical analysis (bivariate correlation and hierarchical cluster analysis) show a possible control of these pollutants on density, diversity, as well as the taxonomic composition of the benthic foraminiferal assemblages. The extent to which the population was found less dense and less diversified corresponded to the degree to which the sediment was contaminated. In these contaminated sites, an increase in relative abundance of opportunistic species such Ammonia tepida and Haynesina germanica was found. Far from pollution, foraminiferal assemblages are dominated by species characteristic of Mediterranean shallow water ( Ammonia beccarii , Ammonia parkinsoniana , Elphidium crispum , Elphidium williamsoni , Elphidium advenum , Peneroplis planatus , Peneroplis pertesus ).

Numerous researches have paid attention to biocomposites. Biocomposite material can be defined as a composite material obtained by products derived from renewable resources such as polylactide acid. The aim of this work was to study biodegradable composites prepared by using cellulose microfibrils (CMFs) as the reinforcement and poly ( d -lactic) acid as a matrix. Five average fiber lengths, from 8 to 300 μm, were used for the biocomposite preparation. The thermomechanical properties, crystallization, and the composites morphology were characterized by the means of dynamic mechanical thermal analysis (DMTA), tensile test device, differential scanning calorimetry, thermogravimetric analysis, X-ray diffraction, and scanning electron microscopy. The effect of fiber length on the thermomechanical properties and crystallinity rate of the composites was investigated. The DMTA results showed that the storage modulus increases with the addition of CMFs. The X-ray diffraction studies, performed on the biocomposites, showed that the crystallinity rate of the blends was improved.

The Tunisian environmental legislation that follows the EC Directives requires monitoring of persistent, toxic and bio-accumulated substances commonly considered as hazardous substances. In order to comply with this requirement, samples of sea water, sediment and biota from the urbanized and industrialized coast line of Sfax city are investigated. This study presents the results of petroleum hydrocarbon content, distribution and probable origin (anthropogenic and/or biogenic) in 16 intertidal sediments of Sfax coastal area. Alkane distribution indices and hydrocarbon distribution patterns are used to identify natural and anthropogenic input. Non-aromatic hydrocarbons present a high concentration with a range varying from 180 to 1,400 μg/g of dry sediment. The total concentrations of polycyclic aromatic hydrocarbons (PAHs) varied from 0.41 to 5.6 μg/g dry weight. These concentrations are comparable to other marine areas that receive important inputs. n-Alkanes with carbon number ranging from 15 to 35 are identified to be derived from both biogenic and anthropogenic sources in varying proportions. Pristane/phytane ratio shows values lower than 1.4 suggesting the presence of petroleum contamination. This is confirmed by the presence of a large group of unresolved complex mixture and the identification of hopanes with predominant C29 and C30 compounds and steranes with predominance of C27 over C28 and C29 compounds. Ratios of selected PAH concentrations indicate petrogenic and pyrolytic origin of hydrocarbons. Anthropogenic hydrocarbon inputs were more apparent at sites associated with industrial discharges, shipping activities and sewage outfalls.