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

The environmental isotopes composition of water ( (cid:303) 18 O, (cid:303) 2 Hand 3 H) 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 calcium-magnesium 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.


INTRODUCTION
In general, water is the most important substance on Earth, without water there will be no life on our planet.Water is everywhere, three quarter of the Earth surface is covered with water in form of oceans, rivers, lakes, swamps and more than 70% of Earth covered by water while 0.014% is surface water.However, the declining water quality of these ecological systems threatens their sustainability and is therefore a matter

Iraqi Geological Journal
Al-Paruany et al.
Vol.50, No.1, 2017 of serious concern.Rivers are waterways of strategic importance across the world, providing main water resources for domestic, industrial and agricultural purposes (Jain, 2009;Bellingham, 2012;and FAO, 2015).
Isotope data from rivers and surface waters were first collected in the 1950s and addressed primarily the variability of stable water isotopes in some large rivers such as the Mississippi and Colorado reported the first tritium values in the Mississippi River and analyzed the mixing of fallout tritium from the bomb tests in the 1950s in the river and adjacent aquifers (Clark, 1954;Dansgaard, 1954;Kaufmann, 1954;and Clark and Fritz, 1997).Isotope ratios of hydrogen and oxygen in river water are indicators for hydrological processes in the catchment (e.g.formation of base flow), for interactions between river water and ground-water, for mixing processes in a river, for travel time and the isotopic composition of hydrogen and oxygen in river water is mainly determined by the isotopic composition in precipitation water in the Drainage area (Mook, 2000;Winston, 2003;and Rank, 2005).
The relationship between the isotopic composition of precipitation (input) and newly formed groundwater and surface runoff (output) is built upon processes that differentiate between rain events on a meteorological or seasonal basis, and processes that fractionate between the different isotopic water species, primarily evaporation (Gat and Tzur, 1967).At any point along a river reach, water is ultimately derived from precipitation falling within its upstream catchment area.Depending on the size and geomorphological characteristics of the catchment, a variety of hydrological processes may affect the catchment and river water flow.The stable isotope ratios of the water molecule ( 18 O = 16 O, 2 H = 1 H) are well-established powerful integrative recorders of key catchment processes (evaporation and transpiration, recycling, mixing) and catchment water balance, as well as tracers of river recharge sources (direct precipitation, runoff, soil water, groundwater, lakes, snow and ice) and The isotopic composition of riverine systems has proven to be a useful tool for estimating the mean residence time and storage properties of surface water.Changes in the isotopic composition of rivers may also help to better characterize the effect of snowmelt events.(Kendall and McDonnell, 1998;Gat, 2003;Henderson, 2005;Jasechko, 2013;and Kattan, 2012).Locally, many publishers have investigated the hydrology and hydrochemistry of Euphrates river (Al-Obaydi, 1983;Al-Hadithy, 2005;andVol.50, No.1, 2017 Al-Bassam, 2011).Also, Al-Paruany (2013) and Ali et al. (2015) have achieved an isotopic and hydrochemistry study on the same area and published their results.This study aims to apply environmental isotope methods, together with hydrochemistry, to monitoring the isotopic composition of the Euphrates River in northwest Iraq highlights the potential of stable water isotopes for tracing the influence of precipitation and other hydrological processes on runoff in tropical rivers.

Description of Euphrates River
The Euphrates River is the longest river in western Asia.with its basin lands (area= 350 000 Km 2

Sampling Strategy
The study area from Qaim to Falluja which has length of about 380 Km.Eight sampls were taken in the study area during two periods of high flow (January 2014) Vol.50, No.1, 2017 and of low flow (August, 2014).Water samples were collected from sites distributed along the Euphrates River course in Iraq.The first sampling site was selected in Al-Qaim, close to the Syrian -Iraq border, while the last sampling site was selected in the Falluja area (Fig. 1).The name of stations and their locations are listed in Table (1).
Unfortunately, water samples were generally collected in three rinsed plastic bottles, and immediately after returning back from the field, all samples were preserved in a refrigerated room (T below 5 °C) until the time of analysis.A small bottle of 50 mL was filled for the determination of stable isotopes ( 18 O and 2 H).A second bottle with a volume of one liter was collected fortritium measurement.
samples for hydrochemistry analysis are collected from same sits, 500 mL bottle was filled for the determination of major ions (Ca 2+ , Mg 2+ , Na + , K + , Cl -, SO 4 and HCO 3 ).Air and water temperature, pH and electric conductivity were measured insitu using a thermometer (accurate to nearest 0.1 °C), pH-meter (model WTW), andconductivity meter ( model WTW 303) respectively.
All data of geology, Topography, industrial uses, drainage water system are observed in order to help for interpretation.

Analytical Methods
Stable isotope analyses were carried out at Water Authority Laboratories/ Jordon.
The methodology as it is described in (IAEA, 1983).Tritium samples were measured using liquid scintillation direct counting in the Sandia laboratory (after electrolysis).
The results are expressed in TU, measurement accuracy for 18 O, 2 H and tritium are ±    .cm - reco -1 at Falluja station in January 2014.

RESULTS AND DISCUSSION
The results of electric conductivity were showed lowest values during January and, while highest values were recorded during August, there was a significant difference recorded among study sites.Euphrates River's water was significantly different among sampling sites and in the two seasons, however the higher in flow season than dry seasons.Higher values of low flow season are possibly due to evaporation processwhich could also increase the concentration of TDS (major ions) (Hem, 1992).
Total Dissolved Solids (TDS) further indicate the salinity behavior of river water.
TDS content of theriver water was in the range of 418 -831 mg L -1 ; 396 -819 mg L -1 in August, Januaryperiods respectively.TDS in water system lead to increase the Ec, Salinity, Cation, Anion level in water.It is considered to be a good indicator for the presence of some dissolved solid substance in water such as the Na, Ca and Mg, SO 4 , HCO 3 .Cl.
Temporal and special evolutions in major ions (Na + , K, Mg, Ca 2+ , HCO 3 Cl and SO 4 ) and TDS concentrations (Figs. 2 and 3) are identical, with rather small fluctuations in the upstream stations and more pronounced variations at downstream stations, The variation in concentration may be due to the input from groundwater salinization, plant fertilizers, pesticides and other pollutants, high irrigation ratesunder arid conditions.
The behavior and distribution of ions along the Euphrates river may be affectedby water hydrology, domestic discharge and many biological, chemical and geologicaloperations in aquatic system.The water chemistry of the Euphrates river is generally characterized by three type of water in both periods of study area: 1. Calcium-carbonate type at stations (Qaim, Ana and Hadith lake).
3. Calcium-sulphate type at (Heet, Ramadi and Faluuja).The depleted values of 18 O and 2 H are found at Haditha reservoir, with values of -7.53 to -7.2‰ and -48 to -49.6‰ on January and August, 2014, respectively.
Similarly, the other stations are also depleted in heavy isotopes.The oxygen-18 and deuterium values show a wide range of variation from -6.3 to -5.5‰ and from -39.2 to -42.2‰ in January, 2014, respectively.While the oxygen-18 and range from -6.3 to -5.0‰ and from -38 to -41‰ in August, 2014, respectively, as shown in Figures ( 4 and 5).The 18 O record exhibits three significant changes along the river.The first is at the Qaim; the second is caused by inflow from the Haditha reservoir with their higher? 18O content; the third significant change in stable isotope ratios in the region of the Ramadi.This variation in both seasons can be attributed to the mixing with water inflowand evaporation.The decrease in 18 O in fall and January is quite an interesting phenomenon.A relatively rapid decrease during the period of January suggests a change in the source of runoff water.The relationships between 18 O compositions and SO4 2-, and between 18 O and   TDS values, are illustrated in Figures (9 and 10).These plots suggest the existence that dissolution processes is controlled for the increasing salinity in the study area: The results of these investigations lead to the conclusion that the relatively big variations of deuterium excess in Euphrates basin precipitation.Deuterium excess is probably no reliable tool to trace the origin of air masses and moisture coming from far away.For this purpose to distinguish between Atlantic and Mediterranean origin.
In the current study, the effects of Haditha lakein the monitoring area,it is clear in both chemical and Isotopic values relative to those other stations, This could be caused by an evaporation effect due to high temperatures.Vol.50, No.1, 2017

Tritium content in the Euphrates River
The tritium values of water samples collected from the Euphrates River at different stations along its course during the period January -2014 are given in Table 2.The data shows that the tritium content of Euphrates River water varies within a very small range (5.6 -7 TU).

CONCLUSIONS
The combination of both hydrochemical and isotopic investigations of surface and lake in the down-stream valley of the Euphrates led to general conclusions, that can be learned from this study, as the following: 1.The Euphrates river water is rather fresh (418 < TDS < 831 mg/L), and its TDS content had slightly increased within the last two decades, most probably as a result of seepage of saline water in the Euphrates river.The chemistry of the Euphrates river water was of a calcium-sodium and sulphate,bicarbonate and -chloride type, and it differs largely from that of local groundwater, which were more saline and The trend of studied hyrochemical formula can be represented as Ca-HCO3 at upstream .
Na-Cl at middle, and in downstream is Ca-SO 4 .

2.
Seasonal variations in concentrations of salinity refer to decrease of these concentrations in wet season, while increase in dry season.And deterioration the water quality of Euphrates River was increase towards the downstream of Falluga city because of pollutants discharge to the river.

3.
The relationships between stable isotopes and major ions suggest the existence of one processes for the increasing salinity (dissolution).

4.
The presence of high tritium content in groundwater confirms that groundwater resources in this zone are of recent age and annually renewable.

5.
Concentrations of stable isotopes generally increase downstream, The tritium content of Euphrates River within Iraq, lower than that of Syria (7.6), changed slightly to around 7 TU.6 multifactors effect to the isotopes values such as residence time in reservoir, irrigation drainage , and evaporation rate.
This paper makes a number of recommendations based on short-and long-term goals.
Given the security situation in Syria and Iraq, the severing of relations between Turkey and Syria,with Continuous monitoring of quality water and insure the environmental strategies need to be improves to protect and enhance the water quality in Euphrates River.

Fig. 1 :
Fig. 1: Map area showing sampling locations Seasonal and temporal variations in the values of physicochemical parameters and total ion concentration at different sampling sites along Euphrates River (Qaim, Ana, Haditha lake, Haditha, Baghdadi, Heet, Rammadi and Falluja) for the Euphrates River are shown in Tables (2 and 3).Vol.50, No.1, 2017

Fig
Fig. : d-excess v 18 O at studied area in January, 2014

Fig
Fig. 9: 18 O compositions and SO4 2-, the relationship in August, 2014 Figure (11)  illustrates the spatial variations of tritium content at eight different stations along the course of the Euphrates River at January 2014.The tritium content of Euphrates River water is apparently higher than that of actual rainfall in Iraq (below 5 -6 TU) during 2013(Al-Paruany, 2013).The cause of high tritium content in Euphrates River water compared to that of actual rainfall is mostly the storing of river water in divers dams in both Turkey, Syria and Iraq.lower than that of Syria (7.6)(Kattan, 2012).It seems that the tritium content of the river water reflects the effect ofresidence time in the different lakes, mainly Al-Assad Lake, Haditha Reservoir, where mean residence time is 201 days respectively.

Fig. 11 :
Fig. 11: illustrates the spatial variations of tritium content at eight different stations along the course of the Euphrates River at January, 2014 with rainfall actual values, 2013 ).It flows 2,700 Km through Turkey (110,000 Km 2 ), Syria (70, 000 Km 2 ) and Iraq (170 000 Km 2 ).and into the Arabian Gulf through the Shatt Al-Arab.The water volume flowing from Turkey through Syria to Iraq has dropped since Turkish and