بررسی عوامل موثربر غلظت نیترات منابع آب شرب زیرزمینی شیراز با استفاده از سیستم اطلاعات جغرافیایی(GIS)

 Background: Nitrate is one of the most prevalent contaminants in groundwater. Ingestion of nitrate in drinking water by infants can cause low oxygen level in the blood which is a potentially fatal condition. In this study the concentration of nitrate and nitrite and contaminant supply in shiraz groundwater by ArcView Geographical Information System 9.3was investigated. methods: In this descriptive study two hundred and twenty groundwater samples were collected from total fifty five Shiraz plain wells in dry and wet season. The concentration of nitrate and nitrite was measured by spectrophotometry. The results was analysis in SPSS, Arcview gis 9.3 Software.   Result: Results showed that NO3 concentration in winter ranged from 4 to 72 mg/L with an average of 31.65 mg/L. In sixty percent of samples, nitrate concentrations was higher than threshold value of 20 mg/L as nitrate and sixteen percent of the samples collected had nitrate concentrations higher than 10 mg/L as nitrogen. Conclusion: from the results, wells’ depth effect on nitrate concentration. Increasing well depth, decreasing Nitrate concentration. The maps showed Nitrate Concentration Increases west to East of the shiraz city. Also, the main Source of contamination in Groundwater was domestic wastewater. One of the important factors was Movement of Water from Karst Aquifer to limestone Aquifer