Seasonal variations of some physicochemical conditions of Shatt al-Arab estuary, Iraq

Abstract

Some physical and chemical investigations of Shatt al-Arab estuary were studied. The transparency as well as the average values of suspended matter generally showed local and seasonal variations. The upstream stations gave high Secchi values and low average values of suspended matter, mainly due to their position relatively further away from the effect of turbidity caused by the tidal currents and the river Karun. The slight decrease of water temperature with depth is related to the mixing processes. The lowest values of air and water temperatures were recorded in January (winter) and the highest in August (summer). The relatively high average pH values found in August and October give a good evidence for the phytoplankton abundance in better environmental conditions. The highest average values of dissolved oxygen were recorded in January and April, whereas the lowest in August and October. The exceedingly high average values of chlorosity found at station VII in January, August and October are attributed to the effect of the Gulf water.