ارزیابی کیفیت منابع آب زیرزمینی دشت شمال قوچان (خراسان رضوی) جهت مصارف آشامیدن و صنعتی

The aims of this study are water quality assessment for drinking and industrial usages with refer to affective factors on water chemistry in North of Quchan plain, Razavi Khorasan province. 17 groundwater samples were collected for major cations (Ca2+, Na+, Mg2+, K+) and anions (HCO3-, SO42-, Cl-) analysis. According to Piper diagram, chemical composition of water samples is 29.4% Ca-SO4, 23.5% Na-SO4, 23.5% Mg-SO4, 11.8% Na-HCO3 and 5.8% Mg-HCO3. Based on Gibbs diagram, the main controlling process of the water composition is mainly water-rock interactions (weathering), rather than evaporation and precipitation. Schoeller diagram shows that most of water samples are categorized in moderate and acceptable classes. Also, based on water quality index (WQI), 70.59 % water samples are suitable for drinking usage. Increasing in SO42- concentration reduced the water quality for drinking purposes. Langelier index (LSI) shows 82.35 % water samples are scale forming and 17.65 % are corrosive. Scale forming of the water are due to high TH induced by carbonate dissolution (of Mozdouran and Tirgan Formations). In addition, corrosive property of some water samples is due to gypsum dissolution (from Shoorigeh Formation) and increasing of sulfate concentration in the groundwater.