INDUSTRIAL DUMPING IMPACT ON OXYGEN AND NITROGEN FLUXES IN ABU-QIR BAY, SOUTHEASTERN MEDITERRANEAN SEA

An input/output flux model was used for the technical assessment of th e effects of the present as well as the proposed reduction in the disc harge of a major wastewater (industrial and sewage) dumping site on th e dissolved oxygen, and nitrogen regimes in the vicinity of the outfal l. Existing data and field measurements were used to feed the model, D uring summer stratification characterized by maximum discharge, mass b alance equations identified different fluxes of nitrogen and oxygen ab ove and below the pycnocline layer, as well as in the top sediment lay er of the receiving system. Parameters such as effluent discharge, atm ospheric reaeration, organic matter decomposition, nitrification, phot osynthesis/respiration, benthic nutrient regeneration, resuspension an d particles deposition were used to represent the physical, chemical, and biological processes included in the model. Different scenarios fo r showing the impact of dumping on the receiving system were exercised . A 50% reduction in the amount of discharge keeps dissolved oxygen le vels in the water column near saturation, accompanied by an increase i n: 1) NH4+1 and NO3-1 concentrations below the pycnocline; and 2) a 16 % increase in the productivity of the upper layer, Sediments appeared to be impacted with the discharge of oxygen demanding wastes, showing a 30-fold increase in organic content over baseline conditions. (C) 19 97 Elsevier Science Ltd.