Hydrochemical Characteristics and Shallow Groundwater Quality in Kirkuk Urban Area, Iraq
Abstract
The assessment of hydrochemical characteristics and shallow groundwater quality was carried out in Kirkuk urban area, Iraq. Twenty two water samples were collected systematically at 20 locations for each of high and low water seasons in April and September (2014) and analysed for physical and chemical parameters. Hydrochmical data suggest that contamination of ground water is caused by infiltration of surface water polluted by domestic seepage pits and leakage from local agricultural area. Depending on hydrochemical facies, the type of water that predominates in the urban area is Ca - Mg-SO4 type during both wet and dry seasons. The study found that Kirkuk shallow groundwater is unsuitable for drinking water and industries purposes but some of water samples are suitable for construction and irrigation purposes.
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Introduction
Groundwater quality in Kirkuk urban area is affected by human activities, such as industrial production, transportation and housing, besides, the continued growth of urban population. The population of Kirkuk city is predicted to increase from 1,050,000 in 2008 to 1,445,556 in 2020 (Omer et al, 2014), which contribute to increase the quantity and size of Municipal solid waste that consider as a source of contamination with the ability to transfer pollutants to groundwater (Mustafa et al., 2013).The presence of residential, local agricultural area, industrial sites, and oil industry in Kirkuk city resulted in waste generation. Industrial waste and fertilizer added to the farmland contribute to change the quality of groundwater after the penetration and reach to the reservoir. The shallow groundwater aquifers represent the uppermost water-bearing zones; so they more susceptible to contamination than deeper aquifers. Groundwater bodies in Kirkuk city are fed naturally by direct precipitation and influent seepage from Khassa River, and artificially by seepage from green spaces and from domestic seepage pit, where Kirkuk’s water department produces about 350000 m3 per day of drinking water (Pollus, 2010). Because Kirkuk city is free of sewage disposal projects, some of these waters may enter groundwater through seepage pits. Populations are used the shallow aquifer for public, domestic and irrigation water supply. Therefore, the population will be at risk of water consumption. This paper focuses on studying and discussing the chemistry and quality shallow groundwater in Kirkuk urban area in detail.
Conclusion
The results of the study show that the main products of urbanization that alter ground -water chemistry were sulfate, nitrate, and chloride generated mainly from seepage of domestic seepage pit in the ancient residential areas and local agricultural sites. Moreover, the elevated sulfate concentrations with calcium reflect the presence of secondary gypsum in the Quaternary deposits. The groundwater quality of the Kirkuk urban area is very hard, fresh to slightly brackish and neutral to slightly alkaline. The results of the hydrochemical indices (Mg/Ca, Cl/HCO 3, and CEV) indicating that the groundwater was inland with respect to origin. The main hydrochemical species in the study area was Ca -Mg-SO 4 that pose 75% of water samples, whereas the other water samples was Ca -Mg-Na-Cl-SO 4 with percentage of 25% for both wet and dry seasons. The suitability of waters for different purposes indicate that all water samples were unsuitable for domestic and industrial uses, but 60% and 40% of water samples were suitable for building and irrigation purposes respectively.