Occurrence, contamination evaluation and health risks of trace metals within soil, sediments and tailings in southern Tunisia

The current study highlights the impacts of mining and ore processing activities on the environment and human health in a south Mediterranean area of southern Tunisia. A geochemical characterization was achieved by analyzing urban soil, stream sediments, mine wastes (tailings, sludge) and phosphate ore, for trace metals "TM" (Cd, Cr, Zn, Mn) have revealed that the samples are highly enriched with metals. An evaluation of the contamination status was attained by calculating pollution indices. Results showed that samples are ranging between moderately and very strongly polluted with TM. Human health risk was evaluated by calculating hazard quotient (HQ), total non-carcinogenic risk (NCR) expressed as hazard index (HI) and carcinogenic risk (CR). The non-carcinogenic risk (NCR) did not exceed the established threshold (NCR > 1) in all studied cases (age or gender based). Thus, local residents of the study area are likely far from developing non-carcinogenic diseases arising from TM exposure. Conversely, CR did exceed the proposed standards (CR > 10(-4)) in some cases. Accordingly, there is a carcinogenic risk associated with children's exposure to Cr. Globally, our findings prove that children of Gafsa-Metlaoui mining area are more vulnerable to TM contamination than adults could develop health complications. To a lesser extent, females are also more vulnerable than males in the concerned area. In order to eliminate any potential health risks, waste management's legislation should be established in Tunisia and similar areas worldwide (open cast-mining, abandoned mine sites, etc.) to control and mitigate the effects of mining and industrial activities on the environment and the human health

Hydrogeological and water quality analysis of thermal springs in the Guelma region of North-Eastern Algeria: A study using hydrochemical, statistical, and isotopic approaches

This study aimed to investigate the hydrogeological features of aquifers in the Guelma Basin using hydrochemical, statistical, and isotopic analyses. The hydrochemical facies of phreatic waters were determined by analyzing 13 parameters of 14 water samples, and correlations between mineralization and contributing elements were identified through statistical analysis. Isotopic analysis was utilized to establish the groundwater's origin. The results showed that water in the Guelma Basin is generally hard, with varying levels of mineralization ranging from significant to excessive. Water quality worsens progressively as it flows in the direction of groundwater flow, particularly in the post-nappe domain due to water/rock interaction. Furthermore, the hydrochemical facies of phreatic waters differed based on their location, with calcium bicarbonates in the upstream and calcium chlorides in the downstream. Through statistical analysis, the study found that mineralization is positively correlated with elements contributing to mineralization, such as Na+ and Cl-. Electrical conductivity (CE) and Residual Salt (RS) were also positively correlated with these ions. Isotopic analysis revealed that the groundwater in the area has an old origin, and the & delta;2H and & delta;18O relationship identified mixing effects in the multi-aquifer system. Additionally, the upward movement of thermal water from deep to shallow aquifers is likely due to the abundance of fractures and faults in the research area. This study provides valuable insights into the hydrogeological characteristics of aquifers in the Guelma Basin and can inform future planning related to water, agriculture, or industry in the region. By using hydrochemical, statistical, and isotopic approaches, the researchers were able to determine the origin and movement of groundwater in the area, which can be useful for future decision-making. Overall, the study highlights the importance of understanding the hydrogeological characteristics of aquifers to make informed decisions regarding water management and resource utilization

Mapping groundwater recharge potential zones in arid region using remote sensing and GIS perspective, Central Tunisia

Given the semi-arid to arid climate in the Regueb region of Central Tunisia, groundwater is a crucial resource for meeting the escalating demands of socioeconomic development. Careful estimation of the current recharge amount and the delineation of potential zones of rainfall precipitation are required for an accurate evaluation of the regional water balance in order to ensure sustainable development and preserve water resources. The aim of this study was to define the prospective locations for phreatic aquifer recharge by doing a preliminary assessment of the groundwater recharge in the Regueb basin. In order to determine the lateral variation of the recharge zone, ArcGIS was utilized in conjunction with a geological and hydrogeological database that was acquired. The obtained results indicated that there are five recharge potential areas: 5% of the study area has very low, 9% has low, 20% has moderate, 28.5% has good, and 36.5% (located principally in the southern part of the study region) has very good recharge potential. This distribution is controlled principally by the geomorphological, geologic, and hydrogeological features of the region. Reasonable management strategies based on the perennial exploitation of these low-renewable resources are required to optimize water-dependent socio-economic development. The environmental risk from groundwater and/or soil pollution and salinization (total dissolved solids (TDS) in groundwater ranged between 1.19 and 16.92 g/L) is undoubtedly explained by the dual actions of climatic conditions and mismanagement of land resources, especially in the agricultural sector, as the study area is mainly devoted to irrigation of vegetation. In addition, this study is helpful in the establishing and managing sustainable groudwater. An isotopic analysis is recommended to aid the decision maker in establishing an adequate strategy

Removal of Vanadium(III) and Molybdenum(V) from Wastewater Using Posidonia oceanica (Tracheophyta) Biomass

The use of dried and re-hydrated biomass of the seagrass Posidonia oceanica was investigated as an alternative and –low-cost biomaterial for removal of vanadium(III) and molybdenum(V) from wastewaters. Initial characterisation of this biomaterial identified carboxylic groups on the cuticle as potentially responsible for cation sorption, and confirmed the toxic-metal bioaccumulation. The combined effects on biosorption performance of equilibrium pH and metal concentrations were investigated in an ideal single-metal system and in more real-life multicomponent systems. There were either with one metal (vanadium or molybdenum) and sodium nitrate, as representative of high ionic strength systems, or with the two metals (vanadium and molybdenum). For the single-metal solutions, the optimum was at pH 3, where a significant proportion of vanadium was removed (ca. 70%) while there was ca. 40% adsorption of molybdenum. The data obtained from the more real-life multicomponent systems showed that biosorption of one metal was improved both by the presence of the other metal and by high ionic strength, suggesting a synergistic effect on biosorption rather than competition. There data ware used for the development of a simple multi-metal equilibrium model based on the non-competitive Langmuir approach, which was successfully fitted to experimental data and represents a useful support tool for the prediction of biosorption performance in such real-life systems. Overall, the results suggest that biomass of P. oceanica can be used as an efficient biosorbent for removal of vanadium(III) and molybdenum(V) from aqueous solutions. This process thus offers an eco-compatible solution for the reuse of the waste material of leaves that accumulate on the beach due to both human activities and to storms at sea