Limnological Studies on the River Tigris, Iraq. I. Environmental Characteristics

Regional and seasonal variations of some environmental characteristics in the 630 km stretch of the lower Tigris were studied and discussed. The lowest air and average water temperatures were recorded in January. The highest average pH values, generally found in October and July, are due mainly to the abundance of phytoplankton. The remarkably low average chlorosity values found in the periods of high water were correlated with the high discharge. The highest average values for dissolved oxygen concentration were generally recorded in January and April, and the lowest ones were observed in October and July.