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Background and Aim: Nowadays, the increasing concentration of pollutants in water resources, especially ground water, has been a matter of concern. Nitrate has been considered as a chemical indicator of water pollution for a long time. The aim of this study was to determine the chemical characteristics of drinking water and changes of nitrate in drinking water in Diwandareh villages. Materials and Methods: This was a cross-sectional study to determine the quality of drinking water of 30 villages in Divandareh. A total of 60 samples were obtained in two phases from water supplies and were analyzed according to the standard methods. Descriptive statistics, Piper, Schuler and Wilcox diagrams were used to interpret the results. Results: The results showed that apart from nitrate, the concentrations of the other chemical quality parameters were below the standard limits. The mean and standard deviation of nitrate during the first and second stages of sampling in water sources were 26.13 ± 25.61 mg L-1 and 28.47 ± 29.80 mg L-1, respectively. According to Schuler diagram, the drinking water quality was moderate to good. Conclusion: Although the mean nitrate concentration in 80% of samples was lower than the latest national standard for nitrate, continuation of the current trend, particularly in the agricultural activities and uncontrolled use of groundwater resources in agriculture will change and lower the quality of water. Therefore, monitoring of agricultural practices and fertilizer use are necessary. Keywords: Water quality monitoring, Water recourse, Water quality indices, Nitrate. Received: Dec 28, 2013 Accepted: March 1, 2014

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Background and Aim: studies show that antioxidants prevent conversion of NO3/NO2 to nitrosamines compounds. tha aim of this study was to determine the potential effect of interaction between dietary intakes of vitamin C and NO3/NO2 on urinary and serum levels of NO3/NO2.
Materials and Methods: This cross-sectional study included 251 adults aged >19 years was performed in the phase 6 of  the Tehran Lipid and Glucose Study in 2015. Food intake was assessed using a semi-quantitative food frequency questionnaire. The average daily intake of nitrate and nitrite and vitamin C was estimated. Serum and urine levels of nitrate and nitrite were measured using  the Grease method. In order to determine the effect of vitamin C on the interaction of nitrate and nitrite in urine and serum, linear regression test was used to modify the effects of confounders.
Results: There was a significant correlation between intake of nitrate and its urine level, above the median level of vitamin C intake (B = 0/004, P-value = 0/004). Also, this correlation remained significant after adjusting for age, sex, body mass index, calorie intake (B = 0.03, P-value = 0/001). The effect of vitamin C interactions on nitrate intake and urine level in the adjusted model for nitrate and nitrite was also found to be significant (B = 0/003 P-value = 0/001).
Conclusion: Increased intake of vitamin C significantly increases urinary excretion of nitrate and it is effective in  the interaction between dietary intakes and urinary excretion of nitrate.

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Background and Aim: Today, environmental pollution, including water pollution, has become a global issue, and human life is dependent on the safe drinking water. This study aimed at spatial analysis of minerals and heavy metals in drinking water distribution network in Kurdistan Province’s villages.
Materials and Methods: In this descriptive-analytical study we assessed the concentrations of nitrate, nitrite, total soluble solids, fluoride, arsenic, lead, and cadmium in drinking water of all villages connected to water distribution network (1524 villages) in Kurdistan Province from 2015 to 2017. To describe the concentrations of the studied chemicals, spatial distribution maps were plotted using Arc GIS V. 10.3 software. Other statistical analyses including the analysis of the mean difference of the concentrations of nitrate, nitrite, and total soluble solids in the studied cities were performed by one-way analysis of variance using SPSS V. 22 software.
Results: According to the results of this study, tap water in 1485 villages of Kurdistan Province (97.44%) contained nitrate and the amount of this ion in the drinking water of 31 villages (2.03%) was above the national and WHO standards. The mean concentration of total soluble solids in Bijar City was significantly higher than that in other cities (P <0.001). The mean concentration of fluoride in the drinking water of rural areas of Kurdistan province was 0.19 ± 0.25 mg/l, which was lower than the value determined by national standard of Iran (0.5-1.5 mg/l). The concentrations of arsenic in the tap water of 47 villages of Bijar (23 villages), Qorveh (11 villages), Saqez (7 villages), Dehgolan (5 villages), and Kamyaran (1 village), respectively, were higher than the maximum permitted value.
Conclusion: Continuation of the current trend, especially in agricultural sector and uncontrolled use of groundwater resources in agriculture, will lead to decreased water quality. Therefore, it is necessary to monitor agricultural activities and use of fertilizers.