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Background and purpose: Safe drinking is water that does not have any chemical and microbial contamination. According to the World Health Organization (WHO) guideline standards for drinking water total and fecal coliform the indicator of fecal contamination must not be detectable in any 100 ml samples. Pollution indicator bacteria such as coliforms and fecal coliforms were enumerated using a multiple-tube fermentation method. Therefore, this study aimed to determine the microbial quality of domestic water wells in rural areas around Sari, Iran with most probable number (MPN) test. Materials and methods: In this cross-sectional study, the microbial quality of water samples from 23 domestic water wells in some villages of Sari were randomly tested in twice to determine the presence of total coliform (TC) and fecal coliform (FC) by the MPN. Sampling and sample transportation and sample analysis were done according to water and wastewater standard methods. Results: The results showed that 87 and 70% of the samples presented total and fecal coliforms, respectively. Water samples of 16 wells were bacteriologically nonpotable. Besides, the results showed that the bacteriological quality of the 3 wells was within the acceptable limits set by WHO guidelines and therefore was safe for human consumption. Conclusion: The results of the study suggested that the level of fecal contamination in domestic water wells was very high. The bacteriological quality of water was not according to the standard of WHO guidelines for drinking water. Therefore, using and drinking water from domestic water wells can pose a great threat and risk of waterborne epidemics by bacterial pathogens to the population consuming it. Water supplying authorities should consider this situation and take measures for the provision of contamination free drinking water to prevent waterborne disease outbreaks.

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Background and purpose: Annually high volumes of Methyl Tertiary Butyl Ether (MTBE) are used as organic solvents in various chemical and fuels as a substitute for lead. These compounds enter the environment after being used and pollute the environmental sources such as surface water and groundwater. Exposures to this organic matter could have acute and chronic influences on human, including nervous system reactions, nausea, and amnesia. Also, the carcinogen formaldehyde is produced after its decomposition in the body. This systematic review investigated the studies carried out in Iran and other countries on the concentration of MTBE. Material and methods: In this study, all papers in national and international databases were examined including Iran Medex, Iran Doc, SID, Google Scholar, Science Direct, World Health Organization, and Pubmed. The keywords used included Methyl Tertiary Butyl Ether, surface water, and groundwater. Overall, 289 articles were retrieved of which 29 were selected after reviewing the titles and abstracts. Results: We found that the concentration of MTBE in ground and surface water were higher than Environmental standards of America (36% and 57%, respectively).The most contaminated samples were taken from North America, Spain and Iran. Conclusion: According to the results some levels of MTBE were detected in water resources in many countries. Due to the high volume of fuel consumption high levels of MTBE enter the environment, so it is essential to take administrative measurements to prevent and reduce the level of such compounds into the environment. Moreover, continuous monitoring of water resources should be carried out, especially in the resources exposed to pollution (such as oil refineries and areas close to gas stations).

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Background and purpose: Pollution of exploitation water resources is increasing throughout the world. Continuous monitoring of these resources could play a key role in reducing such pollutions. This study aimed at evaluating As, Zn, Pb and Cu concentrations in groundwater resources in Toyserkan Plain and preparing the zoning map through GIS. Material and Methods: Groundwater samples were collected from10 selected stations during two seasons in 2012. The samples were filtered (0.45 μm) and maintained cool in polyethylene bottles. Samples were taken for the analysis of cations, the former was acidified with HNO3 (suprapur Merck, Germany) to pH lower than 2. Minor elements (As, Zn, Pb and Cu) were determined using ICP-OES (Varian, 710-ES, Australia). All statistical analyses were performed using SPSS. Kriging method was used for preparing spatial distribution maps of elements in groundwater samples. Results: The results showed that mean concentrations of As, Zn, Pb and Cu in groundwater samples were 3.68±0.76, 3.85±0.84, 1.66±0.35 and 8.59±1.01 ppb, respectively in spring, and 3.99±0.83, 6.30±1.12, 1.85±0.71, and 12.49±1.85 ppb, respectively in summer. The mean concentrations of evaluated metals in groundwater samples were significantly different compared to those of the WHO and IranDOE permissible limits for drinking and agricultural use (p< 0.05). In fact, the mean concentrations of aforementioned metals were significantly lower than the permissible limits. Conclusion: Currently the groundwater resources of Toyserkan Plain are not polluted with heavy metals, but long-term excessive use of agricultural inputs and construction of polluting industries can cause a threat to groundwater resources in this area.

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Abstract Background and purpose: Geographic information system (GIS) and appropriate statistical method for management and analysis of groundwater has been growing rapidly. New devices and information support system has a significant role in management of water resources, especially in limited and valuable water resources. The aim of this study was to evaluate the changes in the physicochemical quality of groundwater watershed in Gharehsou during a ten year period (2003-2012). Materials and methods: The results of water physicochemical parameters analysis were obtained from the regional water authority. The annual average of parameters were determined using descriptive statistics in SPSS Ver.16 by applying Friedman Test and MEASURE with significant level α= 0.05. The annual parameters changes were compared and zoning of different parameters for groundwater quality of gharasoo watershed was determined through ArcGIS9.3 software. Results: The results showed that physicochemical parameters had an increasing trend during the first five years while in the next five years despite annual fluctuations a decreasing trend was observed. No significant correlation was found in annual variation of potassium, calcium, chloride, and conductivity (P 0.05(. Geographically, density and high concentration of chemical compounds in groundwater was seen more in north west, west and south west areas. The most increases of cation and anion concentrations were observed between 2005-2008. Conclusion: The results showed that most of the groundwater watershed contained bicarbonate, and the changes in chemical composition of groundwater watershed depended on rain fall, water harvesting, and type of soil.

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Background and purpose: Fluoride is a major mineral pollutant in groundwater. Long-term exposure to high concentration of fluoride in drinking water causes dental fluorosis, skeletal and non-skeletal fluorosis. Therefore, highly efficient water treatment that could lower the concentration of fluoride in groundwater is a challenge. This study aimed at evaluating the efficiency of Nanofiltration and the effects of pressure and temperature on the removal of fluoride from groundwater.
Materials and methods: The study was conducted in laboratory scale by pilot plant using Nanofiltration membrane (FILMTEC-NF90-4040). Raw water fluoride concentration was between 1.50 and 2.17 mg/L and pressures and temperatures were 4 to 12 bars and 10 to 30°C, respectively. Fluoride ion concentration was measured by spectrophotometry using a standard SPADNS method.
Results: The lowest and highest efficiency rates in removal of fluoride were 30% and 70%, respectively. We also observed that increase in pressure and temperature increased efficiency and the membrane permeate flow rate. Fluoride concentrations in all water samples were less than standard levels.
Conclusion: Nanofiltration was found with favorable efficiency in removal of fluoride from groundwater. Operating pressure and temperature are amongst the parameters that affect the performance of the process and increase the efficiency of fluoride removal by Nanofiltration.