Machine learning-based prediction of toxic metals concentration in an acid mine drainage environment,northern Tunisia

Environmental Science and Pollution Research - In northern Tunisia, Sidi Driss sulfide ore valorization had produced a large waste amount. The long tailings exposure period and in situ minerals...     

Mercury contamination in human hair and some marine species from Sfax coasts of Tunisia: levels and risk assessment

The aim of this study was to measure the mercury (Hg) contents of three marine fish and common seafood species (Diplodus annularis, Sarpa salpa and Sepia officinalis) at two sampling sites in the gulf of Gabes, i.e. Sidi Mansour (polluted site) and Kerkennah (control site). These species are frequently consumed by the population living at the Sfax coasts of Tunisia, particularly by the families of fisherman. Additionally, the hair mercury levels of 55 volunteers (28 women, 27 men) were analysed and the daily total mercury intake through the fish and seafood diet was estimated. The key findings were: (1) the mercury contents of the examined fish and seafood species frequently exceeded the regulatory guideline value of 0.5 mg/kg, (2) no site-specific differences in hair mercury contents were found, (3) fish and seafood consumption is probably the major contributor of mercury exposure in this population, (4) the daily mercury intake through frequent consumption of D. annularis exceeds the US EPA reference dose. Further studies are necessary to evaluate the health risks associated with such high mercury exposure levels in order to allow optimal counseling and therapy of the concerned population and to avoid future impairment of human health, particularly children's health.     

Long-term microphytoplankton variability patterns using multivariate analyses: ecological and management implications

Microphytoplankton data along the southern Tunisian coasts have been monitored weekly since 1995. This study used the data collected during the period 2000–2007 to determine the temporal variability patterns and to characterize the geographical structures of microphytoplankton populations. The methodological approach consisted in isolating the temporal variability common to all sampled sites and in analyzing the “residual” site-specific component. Multivariate ordination methods were used to determine the seasonal and interannual variability. The temporal pattern shared by all sites was highlighted and the seasonal cycle of the most frequent phytoplankton communities contrasted the diatoms winter-spring species to the dinoflagellates summer-fall species. Multitable comparison allowed the identification of three areas exhibiting similar phytoplankton population variability. The results, despite the coastal location of sampling sites, indicated that hydrodynamic and geomorphologic properties of the different areas as well as anthropogenic activities play a key role in the structure of the phytoplankton communities.     

Performance of a small-scale solar-powered adsorption cooling system

In this study, an experimental investigation on the performance of a small-scale residential-size solar-driven adsorption (silica gel-water) cooling system that was constructed at Assiut University campus, Egypt is carried out. As Assiut area is considered as hot, arid climate, field tests for performance assessment of the system operation during the summer season are performed under different environmental operating conditions. The system consists of an evacuated tube with a reflective concentration parabolic surface solar-collector field with a total area of 36 m², a silica gel-water adsorption chiller of 8 kW nominal cooling capacity, and hot and cold water thermal storage tanks of 1.8 and 1.2 m³ in volume, respectively. The results of summer season field test show that under daily solar insolation varying from 21 to 27 MJ/m², the solar collectors employed in the system had high and almost constant thermal efficiency. The daily solar-collector efficiency during the period of system operation ranged from about 50% to 78%. The adsorption chiller performance shows that the chiller average daily coefficient of performance (COP) was 0.41 with the average cooling capacity of 4.4 kW when the cooling-water and chilled-water temperatures were about 31°C and 19°C, respectively. As the chiller cooling water is cooled by the cooling tower in the hot arid area, the cooling water is at a higher temperature than the design point of the chiller. Therefore, an experiment was carried out using the city water for cooling. The results show that an enhancement in the chiller COP by 40% and the chilling power by 17% has been achieved when the city water was 27.7°C.     

Climate change perspectives and adaptation strategies of business enterprises: a case study from Italy

The purpose of the paper is to present empirical evidence on how to develop climate-resilient business enterprises under the auspices of an industrial park management. This was facilitated through the collective mapping of climate adaptation strategies corresponding to the identified business risks exacerbated by climate events directly experienced in the shared territory. The cluster approach attempted to overcome the typical challenges of single business enterprises, mostly small and medium-sized enterprises, with respect to their lack of human and financial resources and scientific and technical knowledge to understand climate change risks. The prospects of facilitating knowledge-sharing and information exchange within a cluster of business enterprises give impetus to the replicability and transferability of the approach in other industrial areas and organizational contexts.     

Antioxidant effect of L-cysteine on sodium-valproate-induced oxidative stress in rat liver: biochemical and ultrastructural approaches

L-Cysteine has protective efficacy in cases of oxidative tissue injury. Sodium valproate is widely used as an anticonvulsant and an antidepressant in spite of hepatotoxicity as side effect. The aim of this study was to evaluate the protective role of L-cysteine in liver toxicity induced by sodium valproate overdose. Release of the hepatic enzymes, aspartate aminotransferase and alanine aminotransferase, and levels of lipid profiles, as well as the oxidative, enzymatic, and non-enzymatic antioxidant were assessed. Liver damage was judged histologically. L-Cysteine decreased the activity of alanine aminotransferase and aspartate aminotransferase, as well as improved the level of lipid profile, increased the enzymatic antioxidant (catalase, superoxide dismutase, glutathione peroxidase and glutathione reductase), and decreased the lipid peroxidation. L-Cysteine administration inhibited liver injury of sodium valproate.     

Study on the kinetics of the conversion of Moroccan phosphogypsum into X2SO4 (X = Na,NH4)

Journal of Material Cycles and Waste Management - Phosphoric acid production industries use the wet process, which leads to enormous quantities of phosphogypsum (PG) as a byproduct. The discharge...     

Semi-solid anaerobic co-digestion of source-separated fecal slag and food waste: focusing on methane production,ecological risk assessment,and quality evaluation as fertilizer

Environmental Science and Pollution Research - Toilet revolution is driven by the urgent need for solutions to improve sanitation and access to high-quality organic fertilizer for rural areas,...     

Bathymetric variation of epiphytic assemblages on Posidonia oceanica (L.) Delile leaves in relation to anthropogenic disturbance in the southeastern Mediterranean

A survey of the epiphytic leaves of Posidonia oceanica was conducted along a depth transect at both the control station Attaya in the Kerkennah Islands and the disturbed Mahres station on the Sfax coast (Tunisia). Samples were collected by scuba divers at depths of 5, 10, 15, and 20 m in July 2008. We evaluated whether the pattern of spatial variability of the macroepiphyte assemblages of leaves of Posidonia oceanica differed in relation to anthropogenic interference. The results indicate that the decrease in shoot density and leaf length according to depth was low at Mahres. The biomass of epiphytic leaves and the percentage cover of epiphytic assemblages decreased with depth for both stations and heavily at Mahres, this decline being related to anthropogenic disturbance. This study shows that the highest values of epifauna and epiflora were detected at the disturbed station Mahres. Macroalgae assemblages decreased with depth at both stations and were dominated by Rhodophyta, whereas the percentage cover of the epifauna leaf that decreases according to depth was dominated by Hydrozoa and Bryozoa. Changes in epiphyte assemblages, epiphytic biomass, percentage cover, and species richness in proportion to Heterokontophyta, Rhodophyta, Cyanobacteria, Hydrozoa, Porifera, and Tunicata between the two stations constitute promising tools for detecting environmental disturbance.