Naouel Dali

This study tested the hypothesis that controlled irrigation with olive mill wastewater (OMW) enhances legume growth while providing an ecological alternative to uncontrolled effluent disposal. The effects of three doses of raw OMW (25, 50, and 100 m³/ha) on two Mediterranean species, faba bean (Vicia faba) and pea (Pisum sativum), were evaluated through agro-physiological parameters (chlorophyll fluorescence, leaf chlorophyll content, total nitrogen) and biochemical markers (proline, soluble sugars, polyphenols), compared to an untreated control. Results revealed a positive correlation between OMW doses and chlorophyll accumulation (15.02% in pea at 50 m³/ha) and nitrogen content, indicating improved photosynthetic activity and nutrition. A marked increase in total phenolic compounds (53.65%) and in proline content (65.11%), a key osmoprotectant, was observed in faba bean at 100 m³ ha^–1, suggesting an adaptive response to physiological stress induced by OMW organic compounds. Biochemical changes and calcareous soils show OMW’s potential as a fertilizer and irrigation source. This is the first evidence of polyphenols and osmoprotectants protecting legumes from OMW, which could reduce the Mediterranean olive oil industry’s environmental impact.

Silicon (Si) is the most abundant element in the earth's crust after oxygen; it is found in aquatic environments as orthosilicic acid. This study concerned for the first time the distribution and flux of dissolved silicates (SiO4) in strategic sites (Charef dam, Bouhamdane dam, and estuary) from the upstream of the Seybouse basin to its mouth to understand silicon biogeochemical transformations under dams and estuarine effects. Surface water sampling was taken and analyzed in the dry (September 2016) and wet (April 2017) seasons. In parallel to sampling dates, physical parameters, and water discharge data were recorded. The highest SiO4 levels were recorded upstream and weakened towards the mouth. It was reduced between 32% and 54% for the Charef and Bouhamdane dams respectively, while the retention rate of the estuary was on average 44%. In terms of flux, the Charef and Bouhamdane dams produced 2 t/yr and 17 t/yr respectively, whereas the estuary produced only 54 t/yr to the coastal zone. Dams and estuarine part play a crucial role in changes in the biogeochemical silicon cycle and are expected to have severe impacts on the river system and the receiving coastline functioning.

Context: Dams construction appears to have multi-dimensional effects on the river environment, and it especially affects the thermal condition of rivers. Aims: The objective of this work was to assess downstream thermal responses to the Charef Dam in relation to the water flow and the water residence time. Methods: During the year 2012, the hydrological parameters upstream and downstream of the dam were monitored. Key results: Salinity, electrical conductivity, total dissolved solids (TDS) and water flow all responded similarly, with larger magnitudes in waters upstream of the dam than downstream, whatever the season. In terms of flux, the Charef Dam retains 59 and 56% of the incoming water and TDS fluxes respectively. Furthermore, the upstream water temperature is higher than that of the downstream in 83% of samples. During the dry season, the thermal response of the waters downstream of the Charef Dam can exceed 2°C (downstream cooling). Conclusions: Despite being a small dam, the water residence time (2.3 years) in the Charef Dam has a significant effect on the downstream water temperature. Implications: These temperature changes may cause significant physicochemical and biological issues. Restoration practices such as increasing discharges during dry seasons and riparian cover restoration could mitigate thermal impacts and minimise negative effects.

Knowledge of the quantity and quality of groundwater is a prerequisite to encourage investment in the development of a region and to consider the sedentarisation of populations. This work synthesises and analyses data concerning the chemical quality of the available water acquired in the Foum el Gueiss catchment area in the Aures massif. Two families of waters are observed, on the one hand, calcium and magnesian chlorated-sulphate waters and on the other hand, calcium and magnesium bicarbonate waters. Multivariate statistical treatments (Principal Component Analysis – PCA and Discriminant Analysis – DA) highlight a gradient of minerality of the waters from upstream to downstream, mainly attributed to the impact of climate, and pollution of agricultural origin rather localised in the lower zones. These differences in chemical composition make it possible to differentiate spring, well and borehole waters. The main confusion is between wells and boreholes, which is understandable because they are adjacent groundwater, rather in the lower part of the catchment area. The confusion matrix on the dataset shows a complete discrimination with a 100% success rate. There is a real difference between spring water and other samples, while the difference between wells and boreholes is smaller. The confusion matrix for the cross-validation (50%).

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