Hydrochemical Evaluation of Surface and Groundwater in Khan Al-Baghdadi Area, Al- Anbar Province / West of Iraq

Received: 29/9/2019 Accepted: 19/4/2019 Abstract The hydrochemical study of the surface and groundwater in Khan AL-Baghdadi area included interpretation of physical, chemical and biological properties of 14 wells and 6 surface water samples collected from Euphrates River.. The study covered two periods representing dry and wet periods in October 2018 and April 2019, respectively. The surface water samples were characterized as slightly alkaline, fresh water, excessively mineralized, calcium-chloride type, and hard to very hard class. While the groundwater samples were characterized as slightly alkaline, brackish water, excessively mineralized, calcium-chloride and sodiumchloride type, and hard to very hard class. The assessment of water for irrigation purposes for both water sources in the dry period showed a Sodium Adsorption Ratio (SAR) of no harmful effects, while the Soluble Sodium Percentage (Na%) demonstrated a good irrigation Water Class, except for one well with a permissible irrigation Water Class. While in the wet period, all surface and groundwater samples were of a good irrigation Water Class, except for two wells with permissible irrigation Water Class. In terms of total dissolved solids (TDS) and electrical conductivity (EC), all surface water samples for the two periods were within the permissible limits of irrigation water quality, whereas groundwater samples for the two periods showed unsuitable limits, except for three wells within the permissible limits of irrigation water quality. The microbiological tests showed that all samples of surface and groundwater are classified as clean.


Introduction
Surface water and groundwater contain different kinds of salts with different concentrations, depending on their sources and the amount of soluble constituents present in the geological formations through which these waters pass [1]. The quality of groundwater depends on its purpose, while the needs for drinking water, industrial water, and irrigation water vary widely [2]. The study area is located in the northwestern part of Al-Anbar governorate, between the latitudes 33 º 47 ' -34 º 0 ' N and longitudes 42º 28'-42 º 45' E. The area of Khan Al-Baghdadi, represents the main focus of the present research ( Figure-1). The region is characterized by a location that is parallel to the Euphrates River.

Materials and Methods
The laboratory works included the physical and chemical analysis of water samples in the laboratory of the Ministry of Science and Technology. It represents a total of 14 well samples and 6 samples from Euphrates River collected in October 2018 and April 2019. The measurements were conducted according to the standard methods [3] and included hydrogen number (pH), EC, TDS, and temperature (T) using TDS-EC-pH-T meter. Calcium, magnesium, chloride and bicarbonate, sodium and potassium were analyzed using flame photometer. Sulfate was determined by spectrophotometer. Trace elements were determined by atomic absorption spectrometer. Rock Ware AqQa version 1.1 was used for classification of water and determination of water type. The coordinates for each sample, including longitude, latitude and elevation were measured using GPS. The accuracy of the results was determined using the equation below [4]: 100 anions r cations r (2) where: U%: Uncertainty (reaction error). A: Certainty or Accuracy.
When uncertainty or reaction error was U%≤5, the results could be certain or accepted for interpretation, but if 5 < U% ≤ 10, the results are probably certain, while if U% >10% the results are uncertain [5]. For assessing irrigation water quality, parameters such as the percentage of sodium (Na%) and sodium adsorption ratio (SAR) were calculated depend on the chemical variables of water samples [6] .The total hardness (TH) was measured by the equation below [7]: TH = 2.497 Ca 2+ + 4.115 Mg 2+ ...…….. (3). Furthermore, TDS (mg/L) and pH values were calculated as in the following equation [7]:

Results and discussion Physical Properties
The main goals of studying the physicochemical characteristics of water are to determine the origin of water and the degree of pollution [11]. The results of physical analysis of the surface and groundwater samples are shown in Table-2.

Samples
No.

Temperature (T)
Water temperature is related to solar radiation and air temperature, where water temperature of streams and springs closely follows air temperature [12]. The temperature of the surface water samples for the dry period ranged between 27.2 and 29.3 with an average of 27.95 ; whereas that for the wet period ranged bet een 24.1 and 28.8 with an average of 26.17 . The temperature of groundwater samples for the dry period ranged 22.3 -28.9 with an average of 24.82 , whereas that for wet the period ranged 19.1 -25.4 with an average of 22.29 .

Hydrogen Ion Concentration (pH)
The pH of surface water samples in the study area for the dry period ranges between (7.4-7.6) with an average ( 7.4), and for wet period ranges (7.0-7.8), with average (7.3). The pH of groundwater samples for the dry period ranges between (7.1-8.0) with average (7.77), and for the wet period ranges between (7.0-7.4) with average (7.66). According to a previous study [13], the water samples are slightly alkaline.

Total Dissolved Solids (TDS)
The TDS of surface water samples for dry period ranges between (635-652) with average (645.3), and for wet period ranges between (614 -637) with average (624.1). TDS of groundwater samples for dry period ranges between (1127 -4589) with average (3132), and for wet period ranges between (1097 -4380) with average (2822). It is clear that the salinity in the dry period is higher than that for the wet period, which is due to the dilution occurring in the wet period as a result of rainfall. According to a previous report [7], all surface water samples for the two periods are classified as fresh water, while the groundwater samples are classified as brackish water. Table 3-Classification of water salinity of the present study according to (Todd, 2007 The EC of water samples for dry period ranges between (1402 -1471) with average (1445.6) , and for wet period ranges between (1313 -1336) with average (1320.3), while the EC of groundwater samples for dry period ranges between (1597 -7543) with average (4836) , and for wet period ranges between (1357 -7247) with average (4410). It is clear that the electrical conductivity in the dry period is was higher than that in the wet period, which is due to the dilution resulted from rainfall recharge to the ground water, leading to a decrease in ion concentration in water during the wet period. According to a previous report [11], the type of all surface and groundwater samples in the study area for the two periods is excessively mineralized water.  The chemistry of water is detected mainly by ion concentrations. More than 90% of the dissolved solids in groundwater can be attributed to seven ions: Ca 2+ ,Mg 2+ , Na + , K + , Cl -, SO 4 2and HCO 3 ⁻ [14]. The results of the chemical examination of the samples from the present study are shown in Tables -(5  and 6).

Calcium ion (Ca 2+ )
The Calcium concentration of surface water samples during dry period ranges between (84-86)ppm with average (84.67)ppm, but during wet period it ranges between (91-97) ppm with average(94) ppm. The higher value of Calcium ion in Euphrates River water is due to the agriculture area and its waste water by irrigation canals. In addition, most Calcium in surface water comes from streams flowing over gypsum, limestone and other calcium-containing rocks and minerals [15]. Calcium concentration of groundwater samples in dry period ranges between (123 -589) ppm with an average (351.22) ppm, while in wet period ranges between (145 -641) ppm with an average (383.5) ppm (Figure-2). The high concentration of calcium in groundwater samples results from the dissolution of limestone of Euphrates Formation in the study area [15].

Magnesium (Mg 2+ )
Magnesium concentration of surface water samples during dry period ranges between (20-21) ppm with average (20.33) ppm, but during wet period it ranges between (25-31) ppm with average (27.67)ppm. Magnesium concentration of groundwater samples in dry period ranges between (47-312) ppm with average (191) ppm, while in wet period ranges between (48-234) ppm with average (136.79) ppm, Fig.2. The main source of magnesium in the studied area is the geological units and dissolution of dolomite limestone of Euphrates Formation [15].

Sodium (Na + )
Sodium concentration of surface water samples during dry period ranges between (78-80) ppm with average (78.33) ppm, but during wet period it ranges between (62-73) ppm with average (66.83) ppm. Sodium concentration in groundwater samples in dry period ranges between (155-578) ppm with average (393.50) ppm, while in wet period ranges between (174-607) ppm with average (390.22) ppm (Fig.2). The source of sodium in the studied area is clay, mineral soil, and evaporation deposits from Fatha Formation [15].

Potassium (K + )
Potassium concentration of surface water samples during dry period, ranges between (2.7-2.9) ppm with average(2.7) ppm, but during wet period it ranges between (0.47-0.52) ppm with average (0.49) ppm. Potassium concentration of groundwater samples in dry period ranges between (2.7-24.7) ppm with average (13.22) ppm, while in wet period ranges between (0.9-1.8) ppm with average (1.19) ppm ( Figure-2). Potassium is commonly present in clays within structures such as illite or adsorbed on other clay minerals [15].

Concentrations of Cations for surface water
Concentrations of Cations for groundwater   ) Sulfate concentration of surface water samples during dry period ranges between (171-178 )ppm with average (174) ppm in, but during wet period it ranges between (158-168) ppm with average(164.5) ppm. Concentration of sulfate of groundwater samples in dry period ranges between (309-1507) ppm with average (952.07) ppm, while in wet period ranges between (298-1697) ppm with average (846) ppm (Fig.3). The main source of sulfate ion in the study area is solutions of sulfate minerals that exist in evaporate rocks such as gypsum of Fatha Formation as well as the anhydrites [15].

Chloride (Cl -)
Chloride concentration of surface water samples in dry period ranges between (141-147) ppm with average 144 ppm, while in wet period ranges between (126-136) ppm with average 130.50 ppm. Chloride concentration of groundwater samples in dry period ranges between (338-1622) ppm with average (981.58) ppm, while in wet period ranges between (329-1236) ppm with average (864.92) ppm (Fig.3). The source of chloride in the studied area is from layers of salts of Halite. The high concentration of chloride in groundwater samples is also due to Halite beds and clay [15]. The decrease of Clconcentration in the wet period is due to the dilution process by rainfall.

Bicarbonates (HCO 3 ⁻ )
When pH is lower than 8.2, the hydrogen ion is added to the carbonate and become dissolved bicarbonate, but when the pH is higher than 8.2, the process of HCO 3 depletion to CO 3 2-in solution becomes faster [19]. The bicarbonate concentration of surface water samples in dry period ranges between (131-137) ppm with average (133.67) ppm, while in wet period it ranges between (132-139) ppm with average (135.3) ppm. Bicarbonate concentration of groundwater samples in dry period ranges between (132-367) ppm with average (183.36) ppm, while in wet period ranges between (93-336) ppm with average (217.86) ppm (Figure-3). The sources of HCO 3 ⁻ in the studied area include clay mineral, soil, and limestone. The high concentration of bicarbonates in groundwater samples is due to the dissolved carbon dioxide in rain water and the solutions of limestone rocks of the Euphrates Formation [15].   [7], and as a result the groundwater in the studied area is classified as very hard water due to wide exposures to limestone in the study area.

Trace elements
Trace elements are defined as metallic elements of atomic numbers that exceed twenty. Their main sources are weathering rocks or human activities [16]. The Euphrates River and groundwater samples were analysed for trace elements (Pb, Zn , Cd , Cu, Cr, Ni and Fe) for the two periods. In the wet period, the concentrations of trace elements were lower than the detection limit of the device , possibly due to dilution processes by rainfall, while in the dry period the device could only detect Fe, Zn.

Classification of Surface and Groundwater Water
The variation in the existing water types points the interaction between factors such as lithology, recharge, geochemistry of the aquifer and depths of the wells [17]. Several classifications were used to determine water type, such as those described by Piper [18]and Shcoeller [19]. When applying piper classification on the water samples from the study area (Fig 4-a,  4 -b), all the water samples for the two periods fell in class e, which represents earth alkaline water with an increased portion of alkali and prevailing sulfate and chloride. Others samples fell in class g, which represents alkaline water with prevailing sulfate and chloride. The development of salty groundwater which exhibits high salinity (3000<TDS<10000 mg.L-1) can be explained by the dissolution of gypsum (CaSO4.2H2O). According to Scholler classification [19], the surface water samples were with prevailing Ca-Cl family and with a group of chloride, whereas the groundwater samples were with prevailing Ca-Cl and Na-Cl families and with a group of chloride.

Water assessment for irrigation
Al-Baghdadi is an agricultural area where the population works in agriculture. The suitability of water for irrigation depends on the kind and amount of salts present in the water and their effects on crop growth and development. Four parameters that are widely used for assessing the water quality (TDS, EC, SAR and Na% ) for irrigation were investigated [7]. The standard categories for each parameter are listed in Table-7 and the results are listed in Table-8.

Sodium Adsorption Ratio (SAR)
The sodium hazard is typically expressed as the sodium adsorption ratio (SAR). High values of SAR indicate a hazard of sodium due to replacing the absorbed calcium and magnesium, a situation ultimately damaging the soil structure [15]. SAR values are calculated according to the following equation [7]: …… (5) All SAR values in all wells studied indicated a Good category, due to high values (more than 3) as shown in the above classification (Table7), whereas all surface water samples were evaluated as having an excellent category due to their lower values (less than 3) ( Table-9).

TDS and EC
The salts, beside affecting the growth of plants directly, also affect the soil structure, permeability and aeration, which indirectly affect the plant growth [7]. According to Don , 1995 classification shown in Table 7, all surface water samples for the two periods were within the permissible limits of irrigation water quality. However, all groundwater water samples for the two periods were within the unsuitable limits of irrigation water quality, except for w2,w3 which were within the doubtful limits of irrigation water quality and w6 which was within the permissible limits of irrigation water quality.

Percentage of sodium (Na %)
Water with an SSP value that is greater than 60% may result in sodium accumulations that will cause a breakdo n in the soil's physical properties [20]. The calculation of Na% can be performed using the equation below [21]: % a a k 100 a g a All ion concentrations are expressed in meq/l. The Na% values of all surface and groundwater samples for the two periods in the studied area indicated permissible irrigation water ( Table-9).

Conclusions
This study provided a detailed description of the physicochemical properties of the surface and groundwater in Khan Al-Baghdadi area at Al-Anbar province, west Iraq. There was no considerable difference in pH values between surface and groundwater, indicating a direct influence on the groundwater by surface water. Concentrations of TDS indicated that the groundwater samples for both periods are considered to be of brackish water, whereas the surface water samples were considered to be of fresh water. Values of EC for groundwater and surface water samples indicated excessively mineralized water for both periods. Total hardness values for groundwater and surface water indicated very hard water and exceeded the permissible limits, due to the wide exposures to limestone and dolomitic limestone in the study area, which are rich in calcium and magnesium. Calcium ion is a predominant cation while Chloride is a predominant anion for surface water samples, whereas Calcium and Sodium ions were the predominant cations and Chloride was the predominant anion for groundwater samples. This might reflect the fact of the presence of limestone rocks and halite mineral, which are the main sources for these ions. As for surface and groundwater suitability for irrigation, all surface water samples for both periods were within the permissible limits of irrigation water quality, but all groundwater water samples for both periods were within the unsuitable limits, except for w2 andw3 which were within the doubtful limits and w6 which was within the permissible limits of irrigation water quality.