مطالعه مکانی و فصلی تغییرات هیدروژئوشیمیایی و بررسی عوامل موثر بر کیفیت آب رودخانه کارده (شمال شهر مشهد)

Abstract Karde river is one of the most important river in Khorasan Razavi province which provides potable water for 3 million inhabitant of Mashhad city. The following research shows seasonal and spatial fluctuation in water quality. Investigating the chemical analysis of Karde rivers water shows that precipitation chemistry doesn't have significant role in the chemistry of river because there is no industrial activity in the region when the Anthropogenic recourses caused by (agricultural fertilizers and sewage) and lithology of the basin have their own roles. Anthropogenic resources has dominant role in late spring and summer when the concentration of NO3-, SO42- and Cl- increases dramatically by chemical fertilizers used in the basin. On the other hand, the concentration of the Ca2+, Mg2+, SO42- and HCO32- in water analysis, Factor analysis and hydrochemical graphs show that dissolution of the carbonate minerals in Mozdooran formation and evaporative and silicate minerals in Shorije formation plays dominant role in the chemistry of the Karde river. Identification of dissolved Carbonate and silicate minerals with ion activity(α) and Log(aCa2+/a(H+)2) versus Log(aMg2+/a(H+)2) graph for Carbonate minerals and Log(aMg2+/a(H+)2) and Log(aCa2+/a(H+)2) versus Log (aNa+/a(H+)2) for silicate minerals show that carbonate minerals Calcite and Dolomite and silicate minerals Kaolinite, Laumontite and Clinochlore beside sulfate mineral gypsum are the dominate dissolved minerals in the river.