Effect of artificial recharge by treated wastewater on the quality of the Korba coastal aquifer (Cape Bon, Tunisia): insights from Boron isotopes.

摘要: Mediterranean coastal aquifers are highly stressed, partly because of intensive agricultural activities in semi-arid or arid context. Water quality groundwater is often degraded by different processes: salt water intrusion, diffuse pollution... In this context, the Korba aquifer on eastern coast Cape Bon (Tunisia) undergoes overexploitation. Since 60's, reversal hydraulic gradient and saline intrusion were studied (Ennabli, 1980; Kouzana et al. 2009a , 2009b; al., 2010) hydrogeological functioning was modeled (Kerrou 2010; Panicoti 2001a, 2001b; Zghibi 2011). Crucial for local agriculture, management led to implementation artificial recharge with treated wastewaters at end 2008. then, monitored trace effectiveness recharge, based boron isotopes, better determine system components. Samples taken from control piezometers farmers' wells. Cation exchange demonstrated be one main processes controlling quality. Sodium, potassium clearly deficit compared a mixing line seawater, whereas calcium, strontium bicarbonates excess. Treated concentrated chloride sodium sometimes more than wells, equivalent 6 14 % sea water. The 2009 isotopic signatures wells distributed between nitrate-polluted salinized pole especially constituted abandoned which had already reached equilibrium governed cation sorption processes, fresh groundwater. This explained intermediate composition less intensively pumped 2010, context low rainwater inputs, general decrease 11B same may indicate deeper groundwaters continuous re-equilibration two previous end-members according e. g. river flows. increased 2010 2011 up their value. Such variation cannot linked simple but appear reasonably higher rainfall after rainy winter. wastewater estimated maximum 30 seemed very local. According fluxes directions, could not influence some composition. impact thus limited terms quality: waters salted poorly contribute refresh system. Ultimately, degradation irrigated soils crops diversity, currently tolerance, will improve. Moreover, B isotopes showed that vicinity impact, if any, close