Impacts of brine disposal from water desalination plants on the physical environment in the Persian/Arabian Gulf

Abstract

Abstract Around the Persian (Arabian) Gulf, a considerable volume of freshwater is obtained by desalination of seawater with the residual brine dumped back into the Gulf. This discharge of saltier waters impacts the marine ecosystem and may also affect dynamic and thermodynamic processes. Here, a fully non-linear, high-resolution numerical model is used to investigate the physical impacts of brine discharge into the Gulf. Twin runs were executed. One with and another without brine discharge at specific points. The results show that, when brine is injected, surface gravity waves irradiate from the locations and induce perturbations in other thermodynamic variables in the far field. Instead of attenuating, the anomalies have long term impact. The differences between the two experiments show marked seasonal and spatial variability. The largest differences occur during the summer and are located mainly along the axis of the Gulf’s deeper channel. After 5 years of run, a budget calculation shows basin wide saline increase of about 0.2 g/kg, in agreement with previous studies. This might appear small when compared with the present Gulf mean salinity. However, the small change seems to be associated with significant variability in the spatial distribution and in the seasonal variability at different locations. It is found that there are regions in the Gulf where the standard deviation may represent serious consequences for living organisms in the marine environment.