Articles
An Investigation of Ground Water Resources Quality in Sistan and Baluchistan Province, 2015
Introduction
Preservation of water resources from contaminants is one of the significant priorities for organizations dealing with water, due to the increasing need for water One of these contaminants includes the leakage and penetration of the contaminants resulted from human activities such as industrial activities into these ground water resources as well as penetration of salty waters (2). In Iran, in particular in southern parts, water resources are severely exposed to the contaminants because of the presence of prevalent contamination sources including salty water of the vicinity lakes, agricultural return flow, and evaporation of shallow ground water (2). One of such areas is Sistan and Baluchistan province which is the biggest province of the country with an area of 187.500 km2, forming 11.4% of the total area of the country (3). Considering the population density, it is one of the lowest populated provinces in the country. Statistical data show that, Sistan and Baluchistan is considered an arid and semiarid province. This, in fact, is confirmed by low rainfall, high temperatures, and high evaporation rate. There are no permanent rivers and streams in this area. Practically, from midspring on, majority of the surface streams dry out (4). Therefore, it is considered a region with poor surface water resources. Hence the major source of water supply in the region is ground water which are used through subterranean streams and wells (e.g., wells supplying the water of Zahedan and Zabol cities) (5). Thus, due to the absence of permanent surface water, life and survival in this arid and desert region is tied to the presence or absence of groundwater resources. Quality of groundwater in the south and southwest regions is very convenient, however, as approaching to the north and northeastern regions, the amount of minerals in the water increase and the quality of the water descends (6). Water quality has always been a concern as one of the most important characteristics of drinking water. Natural water reflects the properties of the soils and rocks it gets in contact with (7). Water quality is usually defined as water sampling and analysis of existing conditions. Chemical testing of water may specify the existence of contamination in the past and present. Hence, to evaluate the drinkability of water for human and limit the consumption of harmful material as well as investigating the material affecting public acceptability of the water, certain predetermined criteria must be regulated and followed (4, 8). For each of these parameters, standard values have been specified in Iran and in the world. The desired turbidity value in Iranian standard and the maximum allowable amount in Iranian and world standard are determined as NTU ≤ 1 and NTU ≤ 5, respectively. The desirable limit of pH in the Iranian national standard and the highest limit are 7-8.5 and 6.5-9, respectively. WHO standard regulates pH as ≤ 8. Taste and odor thresholds for chlorine are 5 and 2 mg/L for distilled water, respectively. Majority of people will recognize the taste of chlorine or its products with concentrations below 5 mg/L. In fact, the taste of chlorine is recognizable in concentrations between 0.6 to 1 mg/L to most people, but has no detrimental effect. In Iran, the standard for highest limit of manganese (Mn), calcium (9), magnesium (Mg), and sodium (10) are determined as 0.5, 250, 50 and 200 mg/L, respectively (4). Other chemical parameters include: fluorine: daily intake of fluoride depends on geographical region. If one’s diet includes fish and tea, the exposure is in particular high through food. Exposure to fluoride in drinking water depends on the temperature, and as the temperature increases, the amount of fluoride in the water must be below 1.5 mg/L (3, 4). Nitrate and nitrite: In many water resources, especially groundwater resources, nitrate level increases as a result of agricultural activities. In Iran, the standard values for nitrate as NO3 and nitrite as NO2 are reported as 50 and 3 mg/L, respectively. Furthermore, due to simultaneous presence of nitrate and nitrite in drinking water, the sum of their concentrations is recommended not to exceed 1 mg/L, and each one of them should not be judged on itself (4, 10). Chloride: the high concentration of chloride results in a taste in drinking water. The highest limit of taste for chloride anion depends on the type of the accompanying cation. This limit for sodium, calcium, and potassium salts of chloride is within 200 to 300 mg/L. There is not any health-based value regulated for it. In Iran, the maximum permitted level of chloride is reported as 400 mg/L on the basis of CL (4, 11). Sulfate: the presence of sulfate in drinking water may result in remarkable taste. Undesirable taste of the water varies with the nature of accompanying cation. The taste limit varies from 250 mg/L for sodium sulfate to 1000 mg/L for calcium sulfate. The unpleasant taste reaches down to the minimum amounts at values below 250 mg/L. Considering the fact that, there are differences between magnesium and sulfate ions in terms of changing the taste and dyspeptic disorders, if the magnesium level exceeds 30 mg/L, the sulfate level must not exceed 250 mg/L. Sodium: the taste limit for sodium is 200 mg/L, and since it is not possible to draw certain conclusions for health effects of sodium, no guideline has been obtained (9-12). Total hardness: the public acceptance for water hardness varies in different societies. The World Health Organization has not set any guideline values for water hardness causing adverse health effects (4, 12). Water with a hardness higher than 200 mg/L, could lead to mass precipitation in the distribution system and the excessive use of soap. On the other hand, water with a hardness of below 100 mg/L, will be highly corrosive to pipes. Total dissolved solids (TDS) and electrical conductivity (EC): TDS is a parameter strongly affecting the taste of drinking water. The water with a TDS of below 500 mg/L is considered an excellent drinking water. A TDS of 500 to 1000 is considered alright and a value in between 1000 to 1500 is allowed for drinking, but water with a TDS value greater than 1,500 is not acceptable as drinking water. Electrical conductivity (EC) shows the ability to pass electrical current through water. This has the same characteristics as TDS. In Iranian standard, the maximum value of TDS is determined as 1500 mg/L. This value is 1000 mg/L according to the standards of WHO. Iranian standards limit the total hardness of water to 500 mg/L, but WHO does not recommend any values (4, 13). Considering the importance of the subject, not only in Iran, but also in all countries, national standards are regulated to preserve the health and welfare of the people in the society (13). To date, many studies have been conducted regarding the subject in different areas of the country (14, 15). In this regard, this study aimed to evaluate chemical parameters of drinking water resources of Sistan and Baluchistan province, and furthermore compare them with national standards.
An Investigation of Ground Water Resources Quality in Sistan and Baluchistan Province, 2015
An Investigation of Ground Water Resources Quality in Sistan and Baluchistan Province, 2015
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WaterTuesday, December 30, 2025