Hydrogeochemical Assessment of Selected Springs Water in Aqra Area, Duhok Governorate, Northern Iraq

Fifteen spring water samples were collected from the study area, to identify its quality, as well as the prevailing water type in it. samples were analyzed to determine the concentrations of main cations Ca 2+ , Mg 2+ , Na + , and K + , and anions HCO 3 - , SO 4 2-, Cl - and NO 3 - , as well as investigating the physio-chemical properties represented by Hydrogen Number, Electrical Conductivity, and Total Dissolved Solids. Piper classification demonstrated that all samples are of type normal earth alkaline water with prevailing bicarbonate with a percentage of 79.9% of all the samples, except for SP4, SP9, and SP11, which characterized with normal alkaline water with prevailing bicarbonate and sulfate or chloride with a percentage of 19.9%. The results of the analysis showed a prevalence of calcium ions over the rest of the cations followed by Mg 2+ , Na + , and K + , and a prevalence of HCO 3 - ion over the rest of the anions followed by NO 3-, Cl - , and SO 4 2. The water quality index showed that all samples are categorized within the excellent type for drinking, with a range of 13.14-29.94. In addition, several classifications used (Eaton, 1950, Turgeon, 2000 and Don, 1995) demonstrated that the water is of excellent type to use for irrigation with Na%=2.51, Sodium Adsorption Ratio=0.08, and RSC=-1.65. Using Wilcox Diagram for irrigation water; show that all samples are within the domain of the excellent water for irrigation.


Introduction
Springs are one of the important sources that provide humans with water for drinking, domestic, and other daily uses.Because water is necessary for all uses, therefore it is important to monitor the sources of water regularly to determine whether this water is healthy or not (Awadh et al., 2021).Moreover, springs are a major source of drinking water, agriculture, and industries in many cities around the world as the water of these springs is of high quality, and on many occasions, it doesn't need filtering or purification before consumption (Awadh and Al-Ghani, 2014;Al-Hamdani et al., 2016).Springs can be defined as those spots of land from which water spurts naturally or forming ponds (Boschetti et al., 2018;Medler& Eldridge, 2021).Also, there is another term, which is seep that stands for a sort of springs that emerge due to the slow movement of water through the slits, pores, and rock perforations and flow out from the surface (U.S. Geological Survey, 2019) and this type of springs is the one that exists in the study area.(Meuli & Wehrle, 2001) explained that the quantity and quality of the spring waters depend on several factors including the annual rainfall, type of rock the water passes through,

The study area
The Aqra area is located in northern Iraq and the eastern part of Duhok, about 85 kilometers northeast of Mosul City.The study area lies between latitudes 36º 31ʹ56ʺand 37 º 02ʹ15ʺ North, and longitudes 43º 54ʹ15ʺ and 44º18ʹ65ʺ East which cover an area of about 1835 Km 2 (Fig. 1).The area bordered on the North and East by the Greater Zab river and from the west Al-Khazir river in addition to a set of branch rivers and creeks.
Aqra climate is the same as the climate of Iraq, it's characterized by a continental climate semi-arid according to the taxonomy and distribution of the climatic regions prepared by Koppen-Geiger which pivots basically on the size of rainfall and the monthly and annual temperatures.So, the area is featured by 763.07 mm as an average rainfall for the period 2001-2020, and 12.17 cm as an average of snowfall, the average annual temperature is 20.75 C°, the highest value of evaporation was 22.4 mm in July, and the average relative humidity was 63.3 % in January for the same period.

Stratigraphy of the study area
The study area is characterized by a variety of geological facies, which are mostly distributed along Aqra and Peris anticlines.Also, it is featured with rough and complicated topography.The Bai Hassan Formation and the sediments of the quaternary spread in the south of the study area and cover a considerable part of it, these sediments are spread to form hills and valleys in the southern and southeast parts of the area, followed by the formations of Al-Mukdadiya, Injana, Fatha, Pila spi, Kolosh, Aqra-Bakhme, and Qamchuqa in the peaks of the mountains.Peris anticline is located to the north of Aqra anticline, and these two anticlines are extending in a parallel manner together, as shown in Fig. 2. The two anticlines consist of various formations, but the limestone and dolomitic limestone prevail, which form Pila spi, Aqra-Bakhme, and Qamchuqa formations.Also, these formations include a great number of cracks, faults, and pores that allow the infiltration of rainwater and snow, and then this water pours out of the surface as springs.At the area between the two anticlines, formations of Fatha, Mukdadiya, Injana, and the sediments of the quaternary are exposed.Aqra and Bakhme formations are consist of reef limestone, Aqra Fm. is locally dolomitized, siliceous, and impregnated with bitumen, Bakhme is secondary dolomitized, the Pila Spi Formation comprises well-bedded, bituminous, chalky, and crystalline limestone, with bands of white, chalky marl, and with chert nodules towards the top (Jassim & Goff, 2006), the formation spreads on both sides of the Aqra fold as a belt with a thickness of 85 m and a widespread, especially in the northwest of the fold depression (Ghafur et al., 2019).The Fatha Formation components are various, it comprises anhydrite, gypsum, and salt inter bedded with limestone and marl, the formation appears in the Aqra fold, as it follows the formation of Pila Spi in an unconformity manner (Aqrawi, 1990).The Injana Formation comprises thin-bedded calcareous sandstone and red and green mudstones (Jassim & Goff, 2006), the Muqdadiya Formation consists of a sequence of gravel, sand, alluvium, and reddish clay stone of different sizes, the Bai Hassan Formation is mainly formed of Massive Conglomerate and involve coarse river components and Conglomerates that represent the river mouths.To the far northern boundary of Aqra (beyond Peris anticline), the complicated topography continues until the Greater Zab River, which separates Aqra from Merga Sur district from the north.

Materials and Methods
Fifteen springs were selected to collect water samples, from the middle of July, until the end of August 2020.Samples locations were dropped by a portable GPS device, the sites from which the samples take; were selected by using ArcMap GIS software after defining the boundaries of the study area.After that, 15 springs were chosen, which are distributed between the center of Aqra city and to the east, and west at the Aqra foothill zone from the northern and the southern limbs, also, some of these springs are distributed at Peris foothill zone, the springs are distributed to various elevations which reach to a height of 910 m.a.s.l.(Fig. 3 and Table 1).the samples were kept in one-liter volume plastic sealed bottles which are rinsed thoroughly with the same water of the samples, and they were filled to the top then these bottles were put in a refrigerator that contains ice to preserve them until they are taken to the laboratory.Analyses were conducted in the laboratories of Duhok Environment Directorate to determine the concentrations of the main cations Ca 2+ , Mg 2+ , Na + and K + ; and the anions HCO3 -, Cl -, SO4 2-, and NO3 -.As Ca 2+ and Mg 2+ ions were estimated using EDTA Titrimetric Method; and the ions Na + and Ca 2+ were measured using PFP7 Flame photometer.Moreover, to measure HCO3 -ions, titration with the sulfuric acid method was used and by using the methyl orange as an index.For the estimation of SO4 2-ions Turbidimetric Method was used by Nephelometer and the Spectrophotometer 420nm after adding a buffer and BaCl2.The concentration of Cl -was estimated by titration with AgNO3 standard solution and by using K2CrO3 solution as an index.to measure NO3 1-a UV Spectrophotometer was used and by adding HCl.Moreover, the hydrochemical parameters Hydrogen number (pH), Electrical Conductivity (EC), Total Dissolved Solids (TDS), and Total Hardness (TH) were determined in the spring waters.To measure and verify the accuracy of the analyses, the ionic balance measure was used the equivalent per million (epm) values for the main cations and anions by using the following formula (Baird, 2017): E% = (Σr.cat.Σr. ani) / (Σr.cat.+ Σr. ani. ) * 100 (1) Where: E% = the percentage of the error Σr.cat = summation of positive ions concentrations (epm) Σr.ani = summation of negative ions concentrations (epm) As for the accuracy, the following formula was used: Where: A = the percentage of analysis accuracy (%).E% = the percentage of the error.
The accuracy of the analyses is very high if the error percentage is less than 5%, but if the error percentage is between 5% -10%, then cautions should be taken in terms of the interpretations.Moreover, if the value was bigger than 10%, then results cannot be relied upon in the hydrochemical interpretations.Also, water suitability for drinking can be determined by using the water quality index (WQI) which is very efficient because it is based on several variables that are formulated digitally, which involves the effect of these variables on the water quality (Salih, 2018) & (Awadh, 2016), WQI can be found by using several equations as follows: (3) Where: (Wi) is the unit weight; (K) is the constant of proportionality and (Si) water quality standards.
Qi = (Vi/Si) * 100 (4) Where: (Qi) water quality rating, (Vi) averages of the data observed, (Si) water quality standards.The value of WQI reflects the suitability of water for drinking and the higher this value is the higher is the unsuitability of water for drinking, as shown in Table 2.For simplicity, assume K=1, and for pH, assuming the same unit weight as for chlorides (0.004), (Pius et al., 2012).The unit weight Wi from equation 3 with K=1, is shown in Table .3with WHO, 2006 and Iraqi guidelines.Also validating of water for irrigation purposes has also been studied through several classifications, which are mentioned below: - The classification that depends on the concentration of Sodium ion percentage, which can be calculated from the following equation: These percentages should be represented by epm If the percentage of Na% was more than 80 then water is considered harmful to the plants and soil (Don, 1995) (Table 4).Moreover, springs water was evaluated for irrigation depending on the sodium adsorption ratio (SAR) as this index measures the ratio of Na + ions to the ratio of Ca +2 and Mg +2 ions.
Sodium has a negative effect on plants as it decreases the soil porosity due to the ionic exchange with calcium and magnesium, which eventually results in soil hardness.
SAR is determined according to the following equation (Todd, 2007): (8) Ratios in the above equation must be represented by epm, the suggested specifications are as in the Table 5 according to the classification of Turgeon (2000).There is another classification related to Eaton (1950), which is the residual sodium carbonate (RSC) depends on the concentrations of bicarbonate relative to the concentrations of calcium and magnesium, which can be determined by the following equation: Ratios in the equation above are expressed by the unit epm.
The high concentration of bicarbonate in water causes an increase in the precipitation of Ca 2+ , Mg 2+ ions in the soil, and consequently, the quantity of sodium in the soil will increase due to the replacement of calcium and magnesium.Using water with a ratio of RSC higher than 2.5 meq/l leads to the accumulation of salts that obstruct the movement of air and water in the soil and eventually result in the deterioration of the soil Table.6 shows the classification of water depending on RSC.
A negative RSC indicates that sodium buildup is unlikely since sufficient calcium and magnesium are in excess of what can be precipitated as Carbonates.A positive RSC indicates that sodium buildup in the soil is possible (Turgeon, 2000).

Results and Discussion
Ideally, drinking water should be colorless and odorless, the color in water is due to the existence of organic materials, minerals, bacteria, and dissolved gases, and this is a preliminary indicator of pollution risk, all samples in the area studies were colorless and odorless .
The average pH value was 7.18, except SP7 and SP10 were reduced to 6.9 -6.7 respectively; this indicates that the water is neutral or slightly alkaline.On the other hand, the average value of EC of these spring waters was 522.5μS/cm and this value is within the accepted specifications of water.the results of representing the springs water analysis by equations 1 and 2 and the results of the analysis of cations, anions, and hydrochemical parameters are given in Table 7.As for the TH, the average value was 294.8 mg/l.the classification of Todd (1980) for hardness, it was clear that the water of the springs SP3, SP4, SP8, SP11, SP12, SP13, SP14, and SP15 falls within the limit of hard water, and SP1, SP2, SP5, SP6, SP7, SP9, and SP10 are within the limit of very hard water.the reason of this hardness is the limestone and the dolomitic limestone that form Aqra and Peris anticlines, but in general, it lies within the international specifications of drinking water that has a limit of >500 mg/l.There is a correlation between water hardness and total alkalinity that results from hydroxide and bicarbonate ions, and when water alkalinity is due to the existence of carbonates and bicarbonate, then the total alkalinity values become close to the hardness (Khalil, 2003).Fig. .4shows the strong correlation between hardness and total alkalinity which was r 2 = 0.79 for the water of springs in the study area (Table 8).The TDS of the spring water in the study area (with an average 334.7 mg/l) are within the freshwater category of the classification of Todd (2005), Table 9 This reflects its validity as drinking water (Fig. 5).For the cations, Table 7 shows a prevalence of calcium as its average value was 77.1 mg/l, the highest calcium ions value was recorded at SP10 which was 100.8 mg/l, this ratio falls within the Iraqi standard specifications for drinking water IQS, 2009 which allows calcium to reach 200 mg/l, but it deviates slightly from the limits of WHO, 2006 which allows the calcium content to reach 75 mg/l this increase is caused by the spread of carbonate rocks in the study area.The average value of magnesium was 24.88 mg/l, from Fig. 6, it is noticeable that the ion increases in the springs SP6, SP7, and SP9 to the east of the city of Aqra towards the Greater Zab River where the Bakhme Formation, which is made of dolomitic rocks.for sodium ions, the average value was 3.07 mg/l; the highest value was recorded at the spring SP9, which originates near the Fatha Formation, which may be a source of this ion in the water, while the lowest percentage was at the spring SP5 on the Aqrah Formation as shown in Fig. 6. for potassium the average value was 0.79 mg/l which falls within the standard specifications for drinking water.The chemical analysis shows a prevalence of bicarbonate ions as its average was 259.7 mg/l due to the tremendous number of the limestone and dolomitic limestone rock in Aqra and Peris anticlines, the percentage of bicarbonate exceeds the Iraqi standard limits for drinking water IQS, 2009, which allows the presence of <200 mg/l but it did not exceed the specifications of WHO, 2006, which allows TDS mg/L Water class <1000 Fresh water 1000 -3000 Slightly saline 3000 -10000 Moderately saline 10000 -35000 Very saline >35000 Brine the presence of <350 mg/l (Fig. 7).The chloride ion concentration was 12.06 mg/l as an average; the highest value was recorded at the spring SP9 18 mg/l, which originates from the contact between Pila Spi -Fatha formation, which is the reason for adding this ion to the water.The sulfate ion concentration in the spring water in the area concerned was 49.72 mg/l as an average; and the highest concentration for this ion was in SP 9 as it was 140 ppm because of the closeness of this spring to Al-Fatha Formation that includes gypsum and evaporates (Fig. 7).Generally, these values are within the limits of drinking water specifications.The nitrate concentration with an average 7.6 mg/l; the highest value of nitrate was recorded at the spring SP15, reason is due to the use of agricultural chemical fertilizers in the area near the spring.To identify the type of water in the study area, Aqua-Chem software was used, with using Piper classification (1944) within this program.The springs water in this area were identified, it was shown that calcium and magnesium are preponderance among the other cations Ca> Mg> Na> K, on the other hand bicarbonate is the preponderance anions HCO3> SO4 > Cl > NO3.It is also clear that the water contains calcium bicarbonate and that all samples lie within the field of normal earth alkaline water with prevailing bicarbonate and it is also observed that the sample SP9 lies within the field of normal earth alkaline water with bicarbonate and sulfate also the samples sp4 and sp11 are so close from the same field, as demonstrated in Fig. 8. Four hydrochemical facies were identified, but the prevailing facies was calcium-magnesium bicarbonate, most of the springs fall within this type with a percentage of 80.0% of all samples, and the spring SP4 is of the type of calcium bicarbonate and sulfate with a percentage of 6.6%, and the spring of SP9 is of the type bicarbonate and magnesium, calcium sulfate, which represents 6.6% and the spring SP11 of the type of bicarbonate and calcium, magnesium sulfate which represents 6.6% of all samples, Table .10shows the springs and the water type and proportions in the study area.The variety in the springs water facies in the area denotes that they flow and stream through different rocky formations, and so they take calcium, magnesium, and bicarbonate from the rock of formations Aqra -Bakhme, Qamchuqa, and Pila Spi, and the sulfate is taken from the Fatha formation, because of many of these springs flow at the contact area between the formations and so this variety in water facies appears.

Suitability of Water for Drinking
After representing the results of the spring water analysis with the equations (3,4,5,6), it was evident that this water is within the excellent field for human consumption as the water quality index showed a very low values, as shown in Table 11.

Suitability of Springs Water for Irrigation
Many classifications were adopted that rely on various variables in the water used.The classification of Train, (1979) was used, as mentioned in Hussein and Al-Salem (2017) (Table 12), which depends on the total dissolved salts.After comparing the springs water in the area in question with these specifications, it was clear that this water causes no harmful effects to the plant as salts concentrations are less than 500 mg/l.

TDS (ppm) Specifications
< 500 Using this water for irrigation causes no harmful effects.

-1000
Using this water could cause harmful effects to the plants which are very sensitive to salinity.

-2000
Using this water might cause harmful effects to many crops so use of this water needs a good expertise.

-5000
This water can be used to irrigate plants that endure high salinity and its use needs a good expertise.Also; after representing results mentioned in Table 7 by the equations 7,8 and 9 and comparing the results with the classifications mentioned in Tables 4,5 and 6 it was clear that these waters are good for irrigation and it has no negative effect on the plants or the soil, as shown in Table 13.The samples were plotted on Wilcox Diagram (1955), which relies on the sodium percentage and the electrical conductivity; diagram is divided into five fields, it was evident that all samples lie within the domain of excellent irrigation water, as shown in Fig. 9.  (Wilcox, 1955)

Conclusions
The springs in the studied area emerge due to the slow movement of the water through the tiny slits, pores, and rock cracks, and they flow out from the surface and it has no relatedness with the groundwater, the chemical analysis showed that these springs water are involved within the domain of hard-very hard water, and this hardness is temporary as it is caused by the ions of bicarbonate, calcium, and magnesium, and the springs of the study area are weakly acidic -slightly alkaline.Results showed that the type of the water is of calcium bicarbonate type and from observing the classification of Piper used; the bicarbonate ions were prevalent for the anions, while calcium and magnesium are the prevalent cations.Therefore, four hydrochemical facies were chemically identified, but the prevalent facies were calcium bicarbonate.Also, the water in the study area is good for human consumption as shown from the low values of WQI as this water is included within the excellent water for human consumption.The validity of the groundwater for irrigation was studied using a group of classifications Na%, SAR, RSC in addition to representing the results on Wilcox Diagram and it was clear that this water is of excellent quality for the purpose of irrigation.

Fig. 1 .
Fig.1.Location map of the study area

Fig. 2 .
Fig.2.The extension of Aqra and Peris anticlines in the area of study

Fig. 4 .
Fig. 4. The relationship between TH and TAl

Fig. 5 .
Fig. 5. Contour maps show the distribution of hydrochemical variables in the springs of the study area

Fig. 6 .
Fig. 6.Contour maps show the distribution of the cations in the study area

Fig. 8 .
Fig. 8. Triple representation (Piper model) for the chemical analysis of the water samples in the study area

Table 1 .
Shows the coordinates of the springs, their elevation, and the geological formation

Table 3 .
The ranges of ions concentrations of the spring water in the study area and comparing them with the acceptable limits of the World Health Organization (WHO) and the standard Iraqi Specifications of drinking water

Table 4 .
Classification of irrigation water depending on the concentration of Sodium

Table . 7
. The concentrations of the cations, anions, accuracy, and hydrochemical parameters for the springs water of the study area

Table 8 .
Classification of water-based on the hardness

Table 10 .
The hydrochemical facies of the springs in the study area

Table 11 .
The mathematical values and WQI values of the springs in the area of study

Table 12 .
the classification of irrigation water depending on the TDS concentration,Train (1979)

Table 13 .
The ratios of the three parameters Na%, SAR and RSC in the water of the study area