Lebanon Post-Conflict Environmental Assessment - UNEP

LEBANONPOST-CONFLICT ENVIRONMENTAL ASSESSMENTThe Ghadir outfall at OuzaiiOne of the river samples had cadmium, seleniumand zinc values above the screening criteria. It wasnot possible to determine the contaminant source,but lower pH is known to increase the solubilityof metals present in soil minerals. Napthelene,a semi-volatile organic compound, was alsodetected marginally above the intervention value(89 ng/l) in one of the river samples. This mayhave been due to fuel oil, and/or antiseptics usedto disinfect fish tanks. Nitrate, which was likely tohave originated from the fish feed, was found atlevels marginally above those expected in naturalwaters. In addition, nutrient loading from feedadditives was observed to have stimulated thegrowth of algal mats in the fish ponds, whichcould deplete dissolved oxygen levels whenthey died and decomposed. However, dissolvedoxygen concentrations in the river water and thefish tanks were within natural range, indicatingthat conditions were not anoxic. Frogs, tadpolesand aquatic insect larva were found to provide abiological indicator of reasonable water quality.UNEP’s assessment is that the destruction ofthe Hermel aquaculture farms created an acutepollution event in the first two to three weeks, butdid not generate a continuous or long-term sourceof contamination. As the strike occurred when theAl-Assi was in its high stage – unlike other riversin Lebanon, the Al-Assi’s discharge peaks in July 14– the spill represented a single pollution slug thatwas largely diluted by the sizeable volume andhigh velocity of the river flow. The medium- tolonger-term risk to the Al-Assi river ecology istherefore considered low in severity and extent.Nonetheless, remaining contaminants presentin the destroyed fish tanks represent a low-levelpollution risk that should be remediated beforethe onset of the next rains and/or floods to preventoverflow. UNEP recommends that plans to cleanup the sites be prepared, taking the possibility ofdecommissioning the facility into account. Plansto reactivate aquaculture farming should furtherinclude collection of baseline water data andmonitoring programme to ensure that it is of asuitable quality.124 • United Nations Environment Programme • United Nations Environment Programme • United Nations Environment Programme •