Journal of Environmental Protection, 2010, 1, 30-40 doi:10.4236/jep.2010.11005 Published Online March 2010 (http://www.SciRP.org/journal/jep) Assessment of Groundwater Quality and its Suitability for Drinking and Agricultural Uses in the Oshnavieh Area, Northwest of Iran Nosrat Aghazadeh1*, Asghar Asghari Mogaddam2 1Department of Geology, Urmia Azad University, Urmia, Iran; 2Department of Geology, Tabriz University, Tabriz, Iran. Email: [email protected], [email protected] Received December 8th, 2009; revised February 27th, 2010; accepted February 28th, 2010. ABSTRACT The Oshnavieh plain is part of the West Azarbaijan province, which is located; 100 km south of Urmia City, northwestern of Iran, and its groundwater resources are developed for water supply and irrigation purposes. In order to evaluate the quality of groundwater in study area, 31 groundwater samples were collected and analyzed for various parameters. Physical and chemical parameters of groundwater such as electrical conductivity, pH, total dissolved solids, Na, K, Ca, Mg, Cl, HCO3, CO3, SO4, NO3, NH3, PO4, Fe, F were determined. Chemical index like percentage of sodium, sodium ad- sorption ratio, and residual sodium carbonated, permeability index (PI) and chloroalkaline indices were calculated. Based on the analytical results, groundwater in the area is generally fresh and hard to very hard. The abundance of the major ions is as follows: HCO3 > SO4 > Cl and Ca > Mg > Na > K. The dominant hydrochemical facieses of groundwater is Ca-HCO3 and Ca-Mg-HCO3 type. According to Gibbs diagrams samples fall in the rock dominance field and the chemical quality of groundwater is related to the lithology of the area. The results of calculation saturation index by computer pro- gram PHREEQC shows that the nearly all of the water samples were saturated to undersaturated with respect to carbon- ate minerals and undersaturated with respect to sulfate minerals. Assessment of water samples from various methods in- dicated that groundwater in study area is chemically suitable for drinking and agricultural uses. Fluoride and nitrate are within the permissible limits for human consumption and crops as per the international standards. Keywords: Groundwater Quality, Hydrochemistry, Hydrogeology, Oshnavieh Plain, Water Type 1. Introduction tity owing to the suitability of water for various purposes [8,9]. Groundwater chemistry, in turn, depends on a Understanding the aquifer hydraulic properties and number of factors, such as general geology, degree of hydrochemical characteristics of water is crucial for chemical weathering of the various rock types, quality of groundwater planning and management in the study recharge water and inputs from sources other than water- area. Generally, the motion of groundwater along its rock interaction. Such factors and their interactions result flow paths below the ground surface increases the con- in a complex groundwater quality [1,10,11]. The rapid centration of the chem. ical species [1–3]. Hence, the groundwater chemistry could reveal important infor- increase in the population of the country has led to large mation on the geological history of the aquifers and scale groundwater developments in some areas. Intense the suitability of groundwater for domestic, industrial agricultural and urban development has caused a high and agricultural purposes. Moreover, pumping tests demand on groundwater resources in arid and semi-arid with the drilling results are the most important infor- regions of Iran while putting these resources at greater mation available for the groundwater investigations, as risk to contamination [12–14]. Groundwater is an impor- they are the only methods that provide information on tant water resource for drinking, agriculture and indus- the hydraulic behavior of wells and reservoir bounda- trial uses in study area. In this study, physical, hydro- ries [4,5]. geologic, and hydrochemical data from the groundwater Hydrochemical evaluation of groundwater systems is system will be integrated and used to determine the main usually based on the availability of a large amount of factors and mechanisms controlling the chemistry of information concerning groundwater chemistry [6,7]. groundwater in the area. The relationship between Quality of groundwater is equally important to its quan- groundwater flow, hydrogeologic properties and hydro- Copyright © 2010 SciRes JEP Assessment of Groundwater Quality and its Suitability for Drinking and Agricultural uses in the Oshnavieh Area, Northwest of Iran 31 chemistry has been studied by many researchers [2,15, K, HCO3, CO3, SO4, Cl), nitrate, phosphate, ammonia, 16]. The chemical quality of groundwater is related to the iron and fluorine using the standard methods as sug- lithology of the area. gested by the American Public Health Association [17]. The Oshnavieh aquifer is part of the Gedar river Sodium (Na) and Potassium (K) were determined by ° ′ drainage basin and lies between latitudes 36 ,57 to flame photometer. Total hardness (TH) as CaCO3, Cal- ° ′ ° ′ ° ′ 2+ 37 ,05 N and longitudes 45 ,01 , to 45 ,15 E. Oshna- cium (Ca ), carbonate (CO3), bicarbonate (HCO3) and vieh plain covers an area of 120 km2 and average ele- chloride (Cl) were analyzed by volumetric methods. vation is 1450 m a.s.l. (Figure 1). The Gedar river ba- Magnesium (Mg) was calculated from TH and Ca con- 2 sin covers approximately 2010 km and river flow di- tents. Sulfates (SO4) were estimated using the colori- rection is almost west-east with utmost discharges into metric technique. Nitrate (NO3), phosphate (PO4), am- the Urmia lake. The most important drainage feature of monia (NH3), iron (Fe) and fluorine (F) were determined the study area is the Oshnavieh, Nilvan and Sheykhan by spectrophotometer. The saturation indexes were de- rivers. The area has a cold temperate climate and the termined using the hydrogeochemical equilibrium model, air temperature is highest in August (26.7℃) and low- Phreeqc for Windows [18]. est in January (–1℃) with an annual average of 13.3℃. 3. Results and Discussion The climate of the study area is semi-arid and it’s aver- age annual rainfall is about 422 mm, which 70% of it 3.1 Geological and Hydrogeological Stting falls during the spring and winter seasons. The most important economic activity in the area is agriculture, From a geological point of view, the investigated area is with the chief crops being beet, wheat and pea. located in the Khoy-Mahabad zone of the Iran [19]. Ig- neous, metamorphic and sedimentary rocks of different 2. Materials and Methods age’s crop out in the basin and range in age from Per- cambrian to Quaternary. Precambrian sedimentary rocks Groundwater samples were collected from 31 shallow consist of green to grey shale and siltstone. Cambrian and deep wells and springs of the area during May 2006. formations in study area chiefly comprise crystalline The location of sampling points is shown in Figure 4. limestone, siltstone, sandstone and dolomite in alterna- The pH and electrical conductivity (EC) were measured tion with dark shale. The Ophiolite formation consists of using digital conductivity meters immediately after crystallized limestone and shale with serpentinized ul- sampling. Water sample collected in the field were ana- tramafic rocks, spite and some schist [20]. Igneous rocks lyzed in the laboratory for the major ions (Ca, Mg, Na, of late Cretaceous age outcrop in many mountain and Mako Caspian Chalderan Sea 39 Tehran Aghchai Iran y e Khoy k r u T Persian Salmas Gulf i cha Zola 38 U r Town m i a Urmia L a Lake k e hai hrc River Sha Osh 37 navieh 0 20 Km Iraq 47 45 46 Figure 1. Location of study area in iran Copyright © 2010 SciRes JEP 32 Assessment of Groundwater Quality and its Suitability for Drinking and Agricultural uses in the Oshnavieh Area, Northwest of Iran including biotite granite, muscovite garnet granite, dio- Formations (Kahar Formation) are semi-permeable. The rite, monzodiorite and granodiorite. The Quaternary Ruteh Formation, alluvium and old terraces are perme- sediments consist of alluvial sandy gravel, alluvial fan able [21]. consists of a clay, silt, sand, gravel and clearly sand. The thickness of this major aquifer increases from the fan Table 1. Stratigraphic relations of the geologic units in the deposits in the west towards the middle and southeast study area showing hydrogeologic properties side of plain. Figure 2 shows the distribution of the out- Hydrogeologic Age Unit Lithology cropping rock formations in the study area. The basin is properties tectonically active and the most important structure that Recent alluvium Gravel, Sand, Clay, affected the geology of the Oshnavieh basin was the Cenozoic Young alluvium Sandy clay and clearly Permeable Aghbolag, Kandvola and Shivehbro fault system. The Old terraces sand exposed lithological units of the Oshnavieh plain range Limestone, Shale, in age from Precambrian to Quaternary and have differ- Eocene Ophiolite Spilite, Schist and impermeable ent hydrogeological characteristics (Figure 2). The strati- Serpentinite graphic succession of study area shows in Table 1. The Permian Ruteh Formation Limestone and Shale Permeable units of similar hydrogeological characteristics are sum- Zaigun, Lalum Siltstone, Sandstone, marized in Table 1 and qualitatively grouped as imper- Cambrian and Barut Shale, Limestone and semipermeable meable, semi-permeable and permeable. Formation dolomite Precam- Schist, shale and Kahar Formation semipermeable In the study area, the Eocene Formations and intrusive brian siltstone rocks are impermeable, and the Cambrian formations Granite, Grano diorite, impermeable (Zaigun, Lalum and Barut Formation) and Precambrian Amphibolite and diabaz 37,5,8 I I om om Legend om I P sr r Town bg di Village ity C eh am vi na sh ule Anticline axis O ola fa Gondv Syncline axis Khaled abad Major faults G edar Kane sorkh River Thrust gb River al Major road Q Nalos sh Minor road Pe e bt1 e bt2 36,57,50 45,1,57 45,15,28 Recent alluvium I Limestone Pr (Ruteh-Fm.) bg Biotite granite t2 Per.