بررسي هيدروژئوشيميايي و تعيين منشاء آلودگي چشمه سرگرو دهلران

Hydrogeochemical study and determination of Pollution Source of Dehloran Sargrou Spring

آلودگي و شوري آب‌هاي زيرزميني خصوصاً در سازند هاي كربناته از جمله چالش‌هاي مهم مديريت آب مي‌باشد. بررسي منابع آلاينده نشان مي‌دهد شرايط تكتونيكي مي تواند باعث تداخل منابع الاينده با آب‌هاي كارستي گردد. لذا شناخت آلودگي‌ها همچنين درك مكانيسم حاكم بر اين فرايند كمك زيادي به تعيين محل تداخل و ارائه راهكار جهت خروج آب قبل از آلودگي مي‌نمايد. چشمه سرگرو يكي از چشمه‌هاي مهم دهلران مي‌باشد كه به دليل كيفيت پايين مورد بهره‌برداري قرار نمي‌گيرد به منظور بررسي‌هاي هيدروشيميايي، در يك بازه 10 ساله، داده‌هاي كيفي چشمه جمع‌آوري شد همچنين جهت تكميل داده‌ها چهار مرحله نمونه برداري در منطقه صورت پذيرفت. جهت تحليل داده‌ها از روش هاي گرافيكي، نموداراي تركيبي، نسبت‌هاي يوني، نمودارهاي تبادل يوني همچنين روابط تعيين كننده شوري استفاده گرديد. نتايج بررسي‌ها نشان داد آب چشمه از لحاظ شرب و كشاورزي غير قابل مصرف مي‌باشد. بررسي نسبت هاي يوني و تبادلات يوني نشان داد مقادير غلظت مولي كلر در تمامي دوره با سديم تطابق نداشته همچنين ساير نسبت هاي يوني در منطقه مويد تبادل يوني معكوس و يا تداخل شورابه عميق نفتي مي‌باشد. بررسي ميزان برم و يد اندازه‌گيري شده و نسب وزني آنها با كلر نيز تاييد كننده اختلاط شورابه نفتي با آب چشمه مي‌باشد.

Groundwater salinity and contamination, especially in carbonate formations, are one of the most critical challenges of water resources management. Carbonate formations in folded Zagros play the role of reservoirs not only for oil but also for water. The study of contamination sources shows that sometimes, tectonic conditions, spatially in Zagros Folded caused interference and adjacent salinity sources from the oil field brine with high-quality karst waters resources. In addition to hydrocarbon contaminants, due to the existence of evaporative formations such as Gachsaran, that are rich in salt minerals, salinity can be infiltration by leaching to the karst water resources. The entry of pollutants from oil reservoirs and evaporation formations reduces the quality of water and creates environmental problems. Therefore, recognizing the contamination and understanding the mechanism of this process can help to determine the location of the contamination mixing point and provide a solution for the discharge of water before contamination. Sargrou is one of the famous springs of Dehloran city which due to the high salinity and the presence of some pollutants is not exploited and the spring water contaminated Dehloran surface water and groundwater. Due to the importance of Sargrou springs in Dehloran area and the qualitative effects of this spring on other water resources, in this research, the hydrogeochemical characteristics of spring water were evaluated. A wide range of studies have been carried out on the evaluation of hydrochemical properties of pollutants in the world (Kalantari et al., 2007; Rezaei et al., 2009; Chitzazan et al., 2012; Masror et al., 2016; Mohammadi et al., 2016; Mirzaie et al., 2012; Marie and Vengosh, 2001; Karimi and Moore 2008; Moore et al., 2009; Wang, 2012). The general method used in these studies included a study of hydrochemical processes, analysis of ions, and the use of ion ratios to determine the origin and interactions of water flow. 2-Methodology Sargrou Springs is located in western Iran, near Dehloran city (one of the main cities of the Ilam province) and is situated 47°17 E longitude and 32°43 N latitude. Fig. 1 shows the location of Sargrou Springs. The altitude of the study area is 290 m above sea level. The average annual rainfall base on the Dehloran rain gage is about 426 mm and the average annual temperature is 26.2 ° C. Sargrou springs characterized by high-temperature water (about 40 degrees) and the exit of sulfur gas from the outlet of the spring. Base on the tectonic divisions, the study area of Sargrou is on the western part of the Zagros folded area. The age of the geological formations that outcropped in the region is related to the Cretaceous lower to the recent. From the old to the new, Sarvak, Pabdeh, Gurpi, Asmari, Gachsaran, Aghajari, and Bakhtiari formations occur in the study area.