DISTRIBUTION OF ENVIRONMENTAL ISOTOPES IN THE EUPHRATES RIVER BETWEEN QAIM – FALLUJA, WESTERN IRAQ

Abstract

The environmental isotopes composition of water (δ18O, δ2Hand 3H) and hydrochemistry concentration were measured seasonally at eight stations along Euphrates River within the study area for two periods (January–Augustm, 2014) to study temporal special variations of these isotopes. The results of isotopes values showed there is a little difference between the periods due to the seasonal change and the trend of distribution can be attributed to evaporation and drainage flow. Generally the river water has positive d-excess, which indicates the vapor source of the Mediterranean moisture sources in January, while a low d-excess associated with enriched isotopic values, which typically occurs during August, 2014. The Euphrates River water, is fresh (TDS < 0.39 g/L) and has slight increase in its salinity levels during the last two decades. Generally the chemical facies changes from a calciummagnesium and bicarbonate type towards a sodium-chloride type to calcium sulfate. River salinity increases according to rock type, lake water, evaporation and human activity, and relatively higher toward downstream stations. The absence of management and a working drainage system, together with irrigation under high evaporation rates and low discharge, are the primary reasons for the continuous deterioration of water quality.