Impact of Brine Discharge from Seawater Desalination Plants on Persian/Arabian Gulf Salinity

The Persian Gulf (also known as Arabian Gulf) is surrounded by desalination plants with about 50% of worldwide capacity to desalinate seawater. Most of these plants dispose of hypersaline effluent (brine) via surface and nearshore outfall into the Gulf. Because energy for desalination increases with seawater salinity, buildup of salt in brine endangers potable water supply there. Brine also contains metals and chemicals (foreign to the marine environment) that have adverse effects on marine ecosystems. Here, for the first time, brine is introduced into Gulf evaporation-driven residual circulation, which controls subbasin flushing, to quantify brine impact on salinity at basin and regional scales. Salt buildup increased mean annual basin salinity (40.5 g/kg) by only 0.43 g/kg, which confirms that basin salinity is insensitive to brine. But regional sensitivity to brine is significant, especially in the southwestern Gulf region near the Arabian coast, where the largest salt buildup raised salinity by about 4.3 g/kg. The results of this study suggests a significant role for brine outfall position in determining brine impact on regional salt levels.