Background & Objectives: Ardabil city with population of about 340386 is still supplied with groundwater resource for drinking. That should have optimum quality standards in different aspects. If a drinking water physicochemical parameters levels is higher than the permitted recommended levels, they may create irreversible damages. This study intended to determine the physicochemical parameters of drinking water in Ardabil in the year 2004.

  Methods: This is a descriptive cross-sectional study that has been done on 35 samples of Ardabil city drinking water resources in 2004. Most of the physicochemical parameters due to their importance and present limitations or even through technical restriction in water and wastewater laboratory of Ardabil health care centers were chemically analyzed and the results were statistically analyzed and compared by 1053 country standard methods.

  Results: According to the results of analyzed samples and their comparison with their related standard, it is estimated that So₄, Po₄ and total hardness of samples were %9, %71 & %41 respectively more than maximum acceptable level. Fluorine of samples was %57 less than the minimum recommended fluorine.

  Conclusion: Due to the lack of consistency in the values of So₄, Po₄, fluorine and total hardness of testing samples with the related standards, programming for obviation of the problems seems essential.

  Background & Objectives: Arsenic is the third element of 5^th Group of the periodic table and it is the twentieth rarest element in the earth's crust. This material has application in agriculture, livestock, medicine, electronics and metallurgy. It enters the environment from natural phenomena and human activities, causing pollution in it. Arsenic is a substance that is poisonous, cumulative, and an inhibitor of SH group enzymes. Several studies have identified significant correlation between high levels of Arsenic in drinking water and cancer in liver, nasal cavity, lungs, skin, bladder and kidney in men and women, and prostate in men. The present study was aimed to determin the impact of parameters affecting reverse osmosis membrane performance in Arsenic removal from drinking water.

  Methods: In this research, Arsenic removal was surveyed and tested through reverse osmosis membrane with spiral-wound module (model: 2521 TE, made in CSM Co. Korea). The used solution was prepared synthetically in the laboratory using sodium arsenate, and system performance was investigated under the influence of parameters such as arsenic concentration, pressure, pH and temperature of the input solution. In each case, the flux rate passing through the membrane and transverse velocity was measured. For each mode, after 30 minutes, desired samples were picked up, and then were tested with silver diethyldithiocarbamate method (Test No. 3500-As B, standard method).

  Results: The results of experiments and measurements showed that the parameters of concentration, pH, temperature and pressure in input solution are effective in reverse osmosis membrane performance (model TE 2521), and the increase or decrease in each parameter leads to changes in the system’s efficiency and performance. The optimal conditions and performance of membrane under the influence of these parameters were defined as follows: pressure 190-210 psi, concentration 0.2-0.5 mg/L, temperature 25-30 ⁰C, and pH = 6-8. Arsenic removal efficiency at the optimum system performance was determined at about 99-95 percent.

  Conclusion: According to the results and the high efficiency and acceptable performance, this approach is effective and can be applied as a method for Arsenic removal in areas with contaminated water.

  Background & objectives: Nitrate is one of the major contaminants in food and water. Excess intake of this substance can increase the risk of stomach cancer and also cause other health problems. The objectives of this study were estimation of dietary nitrate consumption in the Varzaghan with high and Parsabad with low stomach cancer incidence in country, and also the comparison dietary nitrate consumption with World Health Organization standards.

  Methods: In this comparative study performed during autumn and spring of 2011 about 216 food samples (including all food groups) and drinking water collected and their nitrate concentration was determined by colorimetric method. Then daily dietary consumption of nitrate calculated based on daily diet of each person (according to national study on food consumption pattern in Iran) and nitrate concentration in each group of food and drinking water.

  Results: Daily consumption of nitrate in Varzaghan and Parsabad was 8.53 ± 0.35 and 8.17 ± 0.54 mg per kg of body weight (of adults), respectively, which is much greater than the amount recommended by FAO/WHO (0-3.7 mg per kg of body weight). Significant difference was not observed in the dietary consumption of nitrate in two cities at studied period (P> 0.05).

  Conclusion: Despite of no significant difference in dietary consumption of nitrate in two cities, the daily consumption of nitrate in both of studied cities was significantly greater than the recommended level. Therefore monitoring sources of contamination and reduction of environmental pollution for decreasing food nitrate concentration are recommended.