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Assessment of the physicochemical quality of drinking water resources in the central part of Iran.

Introduction

The basic and essential requirement in water works is to provide the public with an adequate supply of safe drinking water (World Health Organization [WHO], 2011). Preserving the safe quality of water is vital to sustain life, protect human health, and contribute to social development (Vrba & Lippon, 2007). As the 20th century progressed, the identification of chemical water pollution became more important due to the outbreaks associated with chemical spills or leaks into potable water. In the mid 1970s, an event occurred that led to concern about chemicals in water because of chloroform in finished water treated with chlorine (Calderon, 2000). The Centers for Disease Control and Prevention (CDC) reported 34 waterborne disease outbreaks from 1993 through 2006 in the U.S. related to chemical constituents including nitrate and nitrite, fluoride, and lead (Post, Atherholt, & Cohn, 2011).

Health risk concerns related to chemical contamination of drinking water differ from those related to microbial contamination and arise mainly from the ability of chemical constituents to cause adverse health effects after an extended time of exposure (WHO, 2011). Changes in water quality occur progressively except for those substances that are discharged or leach intermittently to flowing surface waters or groundwater supplies from contaminated landfill sites (WHO, 2011). The problem of chemical contamination in drinking water bodies may cause several health problems. Tooth discoloration and skeletal fluorosis are caused by excessive fluoride intake from drinking water (Maheshwari, 2006; WHO, 2011). A high content of nitrate and nitrite leads to methemoglobinemia in infants less than six months of age and also possible formation of nitroso-compounds that are known to be carcinogens in the digestive system (Manassaram, Backer, & Moll, 2007).

Iron and chloride are also of widespread significance because of their effects on water taste and acceptability (American Public Health Association [APHA], 2012; WHO, 2011). Iron concentration in drinking water above the acceptable limit can be objectionable because it stains laundry and may affect taste (WHO, 2011). Turbidity is a principal physical characteristic of water quality that could provide absorption sites for toxic substances and microorganisms in the water and subsequently protect pathogenic and indicator microorganisms from disinfectants (Edzwald, 2011). Total dissolved solids (TDS) is the term used to describe the inorganic salts and small amounts of organic matter present in a given amount of water (APHA, 2012). Reliable data on possible health effects associated with the ingestion of TDS in drinking water are not available (WHO, 2011). The WHO guideline value of 1,000 mg/L for TDS is based on the taste and acceptability rather than health effects. Acceptability may vary according to circumstances. Furthermore, water with extremely low concentrations of TDS may also be unacceptable to consumers because of its flat, insipid taste (WHO, 2011).

Many studies show groundwater pollution from chemicals is a growing problem worldwide that is caused by numerous types of human activities (Babiker, Mohamed, Terao, Kato, & Ohta, 2004; Celik, Unsal, Tufenkci, & Bolat, 2008; Fang & Ding, 2010; Hudak, 2012; Kumar, Kumari, Ramanathan, & Saxena, 2007; Lee, Min, Woo, Kim, & Ahn, 2003; Loni & Raut, 2012; Nas & Berkaty, 2006; Subramani, Elango, & Damodarasamy, 2005). The water quality is highly affected by residential, municipal, commercial, industrial, and agricultural activities (U.S. Environmental Protection Agency, 1993). Deterioration of groundwater quality especially in arid and semiarid areas is a major concern that has been intensified by population growth and increases in demand for food supplies. Decreasing rainfall combined with increased evaporation from increased temperature as a result of climate change will affect groundwater levels in these regions (Wilby et al., 2006). The lack of adequate water resources and access to safe drinking water in arid and semiarid regions cause serious health hazards and expose many people to health risks (Schmoll, 2006). Thus, providing safe drinking water through proper management and monitoring of water resources is vital for the protection of public health and environmental safety.

Iran is an arid/semiarid country with an average precipitation of 251 mm/year (Assadollahi, 2009). The entire renewable water resource in Iran totals 130 billion cubic meters, out of which 92% is used for agriculture, 6% is used for domestic use services, and 2% is used for industrial uses (Assadollahi, 2009). For this reason, our study was designed 1) to assess the quality of water resources in the central part of Iran, which uses water after chlorination and without any additional treatment for drinking; and 2) to evaluate the impact of decreasing rainfall on the quality of some water resources in two successive years.

Methods

A total of 65 raw water samples were collected in clean polyethylene bottles between June and November 2012 from different drinking water resources including wells, springs, and aqueducts in Isfahan province. Isfahan province is located in the center of Iran; it has a moderate and dry climate with an average annual temperature of 16.7[degrees]C and an average annual rainfall of 116.9 mm (Assadollahi, 2009). The sampling, preservation, and analysis of water was carried out as recommended by the American Public Health Association (2012).

The turbidity and electrical conductivity (EC) were determined and EC measurements were converted to TDS values by multiplying EC by a factor of 0.55 as recommended for water resources (APHA, 2012). The concentrations of nitrate, nitrite, and fluoride were assayed by DR5000 according to manufacturers' instructions and chloride concentration was determined by the Mohr method. Iron analysis of water samples was carried out using a flame atomic absorption spectrophotometer.

In order to evaluate the effect of decreasing rainfall and increasing temperature on resource water quality, 12 water resources were randomly selected and the concentration values of three important parameters including nitrate, chloride, and TDS in 2013 were compared with the data in 2012. Meteorological parameters were also obtained from the weather bureau.

Statistical analyses of data were performed using SPSS with a confidence limit of p < .05. A normality test was performed for distribution of chemical value to decide if parametric or nonparametric test procedures must be employed. In addition, to compare mean values of physicochemical parameters, Fisher's least significant difference procedure was used to determine the significant differences between group means in an analysis of variance setting.

Results

In our study the quality of 65 water resources in the central part of Iran that used water after chlorination and without any additional treatment for drinking was assessed. The results showed that the quality of examined water resources was mostly acceptable with respect to the standard guideline values recommended by WHO (Tables 1 and 2). In some samples, however, the measured parameters exceeded the acceptable level. According to the analysis of water samples, the TDS values showed a high degree of variability, ranging from 2.12 to 1,754.5, with an average 452 mg/L (Table 1). TDS content of about 91% of samples, however, was below the permissible limit set by WHO for drinking water (Table 2). In addition, water with a TDS level of less than 600 mg/L is more pleasant (WHO, 2011). We observed that TDS levels were as follows: about 69.4% of samples had excellent TDS (<600 mg/L), 21.5% were good (<1,000 mg/L), and 9.2% of samples had higher than 1,000 mg/L. Although the WHO guideline value for TDS is based on the taste and acceptability rather than health effects, the taste is a basic criterion for consumers to decide on the suitability of a water source for drinking.

Iron and chloride could also raise complaints from consumers due to their effect on taste and color. Chloride concentration varied from 8 to 400 mg/L and 9.2% of samples had a concentration beyond the acceptable limit set by WHO for drinking water (Tables 1 and 2). This study showed a significant difference in the levels of chloride in spring samples compared to well and aqueduct samples.

Iron concentration of samples ranged from 0.01 to 1.23 mg/L and 6.8% of samples had a concentration more than 0.3 mg/L.

Comparison of the analytical results with the acceptable limit of measured parameters showed that the highest percentage (12.3%) of water resources contamination was related to nitrate pollution (Table 2). While water resources were highly polluted by nitrate, nitrite concentration in all samples was within the permissible limit and with a mean value of 0.006 mg/L, ranging from 0.001 to 0.045 mg/L. In addition, the highest concentration of nitrate (15.4 mg/L as N) was found in the well water sample (Table 2), and a significant difference occurred between the nitrate concentration in well water and spring samples.

Observed fluoride concentrations revealed that 1.5% of samples exceeded the acceptable limit (Table 2). Only 52.3% of samples had fluoride levels in accordance with the WHO guideline (0.5 to 1.5 mg/L), which is recommended for children during the time of developing permanent teeth. Also, 46.2% of samples had fluoride levels lower than the recommended level (<0.5 mg/L). The highest concentration of fluoride was detected in the well water samples, and spring waters generally had 0.5 mg/L of fluoride or lower in 90% of samples.

Turbidity does not have a health-based guideline, but to ensure effectiveness of disinfection it should be no more than 1 nephelometric turbidity unit (NTU) and preferably much lower (WHO, 2011). In addition, under the Long-Term 1 Enhanced Surface Water Treatment Rule, drinking water cannot exceed 1 NTU and must be under 0.3 NTU in 95% of each month's tests (Edzwald, 2011). Although only 3.1% of samples had turbidity levels beyond the acceptable limit set by WHO for drinking water (>5 NTU), turbidity levels in 23.1% of samples were also less than perfect (Table 3). Furthermore, turbidity below 0.1 and 0.3 NTU according to the WHO and Ireland's Environmental Protection Agency guidelines, respectively, could ensure water safety based on the removing of chlorine-resistant pathogens such as Giardia and Cryptosporidium (Environmental Protection Agency [Ireland], 2009; WHO, 2011).

In order to identify the possible association between the measured parameters, a correlation analysis was performed and the results are presented in Table 4. According to the correlation analysis, a high positive correlation was found between TDS, chlorine, fluoride, and nitrogen dioxide (Table 4). As EC and TDS are mainly contributed from salts of sodium, potassium, sulfate, chlorine, and other minerals (Babiker et al., 2004), this correlation was expected. This result is consistent with other studies that reported the increase or decrease of TDS and turbidity values were related to the increase or decrease in the values of inorganic salts and small amounts of organic matters in water (Gupta, Sarkar, & Bhardwaj, 2012; Kanade & Gaikwad, 2011). Also in association with iron levels, we noticed a positive correlation between iron and turbidity levels. Turbidity in some groundwater resources is a consequence of inert clay or chalk particles or the precipitation of nonsoluble reduced iron and other oxides when water is pumped from anaerobic waters (WHO, 2011). Other physicochemical parameters of water were not statistically significant.

Mean values of nitrate, chloride, and TDS concentration in two successive years are presented in Table 5. As shown in this table all values were increased in 2013 in comparison to 2012 and the increase was significant for nitrate and TDS. In comparison to the results of analyzed parameters in 2012, however, the concentration of nitrate for only one sample exceeded the standard guidelines. According to the meteorological information, the mean rate of annual rainfall from October 2011September 2012 to October 2012-September 2013 reduced about 13.9%-14.5% in most regions. Temperature increased, however, about 1[degrees]C-1.5[degrees]C in all regions.

Discussion

Groundwater is an important source of water worldwide and is particularly vulnerable to the direct and indirect effects of industrial and agricultural activities as well as climate change. According to the results of our study, the quality of drinking water resources in the central part of Iran is mostly acceptable and satisfactory (Table 2). Comparison of physicochemical parameters concentration among the different water resources indicated that the water obtained from springs is better than the other water resources except for iron levels (Table 2), which could be attributed to the stratigraphic structure (Nemerow, Agardy, & Salvato, 2009). Since iron is frequently found in water due to large deposits in earth's surface (WHO, 2011), spring samples contained more iron concentration that exceeded the acceptable limit. Additional study is required to provide the detailed mechanisms of such effects.

Higher levels of TDS and chloride in well and aqueduct samples compared to spring samples could be related to the natural occurrence of this mineral in deep aquifers (WHO, 2011). Furthermore, pollution of water resources by wastewater could also increase the chloride concentration (WHO, 2011). Results of Rossiter and co-authors (2010) and Kumar and co-authors (2007) also showed that around 5.7% and 6.6% of well and borehole water samples, respectively, have higher chloride concentration than the permissible limit set by WHO for drinking water. Comparison of TDS and chloride concentrations in aqueduct and well samples showed that aqueduct waters were contaminated more than the well waters. This may be explained by the structure of aqueducts, which is an underground system with a series of well-like vertical shafts that facilitate the arrival of point or nonpoint pollution to this source (Assadollahi, 2009). In contrast to TDS and chloride, the highest concentration of fluoride was detected in the well water samples. In a study conducted by Rossiter and coauthors (2010), fluoride concentration varied from <0.1 to 4.238 and about 6.7% of the well and borehole water samples had concentrations above the permissible limit set by WHO for drinking water (1.5 mg/L). Kortatsi (2008) also reported that about 17% of the well and borehole water samples contained fluoride concentrations above the permissible limit.

The results of our study also showed that the highest percentage of water resource contamination was related to nitrate pollution. The result is consistent with other studies that reported that nitrate is the most frequently introduced pollutant into groundwater systems (Babiker et al., 2004; Fang & Ding, 2010; Nishikiori, Takamatsu, Kohzu, Nakajima, & Watanabe, 2012). Nitrate may be present in groundwater resources as a consequence of the excess application of inorganic or organic fertilizer as well as wastewater from industrial activities (WHO, 2011). According to the European Environment Agency report, the percentages of wells with an annual mean nitrate concentration of higher than the European Union standard for drinking water (11.3 mg/L as N) were observed in the UK (15%), Italy (10%), Spain (25%), Germany (15%), and France (9%). In the U.S., 8% of wells sampled from 1991 to 2003 had a nitrate concentration more than the permissible limit set by the U.S. Environmental Protection Agency for drinking water (Nishikiori et al., 2012). In Japan, 4% of wells contain water with nitrate levels that exceed the Japanese environmental standard for groundwater (Nishikiori, 2012). In Iran, several studies have reported groundwater contamination by nitrate due to agricultural activities and heavy leaching of pollutants from pesticides and fertilizers to the aquifers (Ghaisari, Atosa, Najafi, & Hodaji, 2007; Khosravi, Mosavi, & Afyoni, 2006; Malekabadi, Afyoni, Mosavi, & Khosravi, 2004). We frequently observed the nitrate contamination in well water samples without the presence of other contaminants such as chloride and TDS, which could reflect the high impact of human and especially agricultural activities on well waters (MacDonald & Calow, 2009).

Among the studied regions, water resources in Falavarjan city were more polluted than the others. This may be due to the intensity of agricultural and industrial activities in this region. The results also showed that when the distance increased from farmland and industrial regions, the chemical levels in the water resources decreased. Previous studies also have reported high values of chemical concentrations in the water samples of these areas (Amin, Ebrahimi, Hajian, Iran-panah, & Bina, 2010; Malekabadi et al., 2004). Since this area is one of the most important industrial and agricultural regions in the central part of Iran, different issues of water resources management such as quality and quantity conservation, planning for water allocation for agricultural uses, industry, and drinking water issues have arisen in regard to the fluctuations of chemical parameters, particularly nitrate. This finding also indicates that inadequate attention to water resources in these regions may enhance the presence of other chemical pollutants, particularly heavy metals. It is therefore essential to determine the quality of these water resources on the basis of other chemical pollutants.

Quality monitoring of a number of resources in two successive years showed that the quality has been mostly impacted by increased concentration of nitrate, chloride, and TDS (Table 5). The quality of groundwater is highly dependent on the geochemistry of soil and rocks through which it moves and also anthropogenic pollutants (Bloomfield, 2013). Water quality may be impaired, however, if decreases in annual mean rainfall cause contaminants to become more concentrated. In addition, in arid and semiarid areas, the quality of shallow groundwater may be affected by an increase in salinization due to increased evaporation (Bates, Kundzewicz, Wu, & Palutikof, 2008). Based on the relatively stable conditions of studied areas in the present study, the higher concentration of analyzed parameters in 2013 than in 2012 is likely due to increased salinization as a result of rainfall reduction and increase of temperature. This effect could be confirmed by simultaneous increases in average concentration of nitrate and TDS (Table 5). In addition, sequences of dry summers in arid and semiarid areas lead to the buildup of inorganic nitrogen in the soil and an increased risk of leaching from soil into water resources (Stuart, Gooddy, Bloomfield, & Williams, 2011; Wilby et al., 2006). Nitrate concentration is predicted to rise in many places over the next decade as the most widespread groundwater quality problem (Stuart et al., 2011). Wilby and co-authors (2006) state that rising temperature as a result of climate change will lead to higher nitrate concentrations throughout the 21st century until a plateau is reached in 2050. Long-term monitoring of a high number of water resources is required to understand the impact of climate change on water quality in arid and semiarid areas. This is particularly essential for ensuring the sustainability of future water resources (Bloomfield et al., 2013).

Conclusion

In general, the quality of drinking water resources in the central part of Iran in the present status is mostly acceptable and satisfactory. Water quality may be impaired, however, if decreases in annual mean rainfall cause chemicals to become more concentrated. Therefore, continued monitoring of water resource quality in arid and semiarid areas is extremely important for the protection of human health and environmental safety.

Mahnaz Nikaeen

Isfahan University of Medical Sciences

Ali Shahryari

Golestan University of Medical Sciences

Mehdi Hajiannejad

Hossein Safari

Zahra Moosavian Kachuei

Akbar Hassanzadeh

Isfahan University of Medical Sciences

Acknowledgements: This research was conducted with funding from the vice chancellery for research at the Isfahan University of Medical Sciences (Grant No: 390530) as a part of a PhD dissertation.

Corresponding Author: Ali Shahryari, Assistant Professor, Environmental Health Research Center, Golestan University of Medical Sciences, Gorgan, Iran. E-mail: al_shahryar@yahoo.com.

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TABLE 1
Statistics of the Analytical Results of Measured Parameters From
65 Drinking Water Resources

Parameter               Mean [+ or -] SD      Minimum   Maximum

Turbidity
  (nephelometric
  turbidity units)     1.07 [+ or -] 1.61      0.08      9.26
Electrical
  conductivity
  ([micro]s/cm)      821.96 [+ or -] 717.11    3.85      3190
Total dissolved
  solids (mg/L)      452.08 [+ or -] 394.41    2.12     1754.50
Nitrate                5.35 [+ or -] 3.77       0.6      15.40
  nitrogen (mg/L)
Nitrite               0.006 [+ or -] 0.006     0.001     0.045
  nitrogen (mg/L)
Chloride (mg/L)       93.70 [+ or -] 96.32      8.0      400.0
Fluoride (mg/L)        0.57 [+ or -] 0.36      0.01      1.60
Iron (mg/L)            0.10 [+ or -] 0.21      0.01      1.23

TABLE 2
Comparison of Water Resources Quality With World Health
Organization (WHO) Guideline Values for Drinking Water

                                       % Samples Exceeding
                      WHO              the Guideline Value
                    Guideline
Parameter            (mg/L)     Well   Spring   Aqueduct   Total

Total dissolved       1000      7.5     0.0       20.0      9.2
  solids (mg/L)
Nitrate nitrogen      10.0      17.5    0.0       6.7      12.3
  (mg/L)
Nitrite nitrogen       1.0      0.0     0.0       0.0       0.0
  (mg/L)
Chloride (mg/L)        250      10.0    0.0       13.3      9.2
Fluoride (mg/L)        1.5      2.5     0.0       0.0       1.5
Iron (mg/L)            0.3      8.6     11.1      0.0       6.8

TABLE 3
Percent Frequency Distribution of Turbidity
in Different Water Resources

                 Turbidity (NTU (a))

Source      <0.1    0.1-1      1-5       >5

Well         2.5     65.0     27.5      5.0
Spring      10.0     80.0     10.0      0.0
Aqueduct     0.0     80.0     20.0      0.0
Total        3.1     70.8     23.1      3.1

(a) NTU = nephelometric turbidity units.

TABLE 4
Correlation Matrix of the Measured Parameters
in Water Resources

Parameter            Iron     Fluoride     Chloride

Turbidity          0.344 **     0.000      0.292 **
Total dissolved     -0.145    0.545 **     0.886 **
  solids
Nitrate             -0.055      0.064       0.200
Nitrite             -0.022    -0.312 **     -0.162
Chloride            -0.022    0.411 **
Fluoride            0.036

                                            Total
                                          Dissolved
Parameter          Nitrite     Nitrate      Solids

Turbidity           0.031      -0.097       0.087
Total dissolved    -0.238 *     0.181
  solids
Nitrate             -0.099
Nitrite
Chloride
Fluoride

* Correlations are significant at p < .05.

** Correlations are significant at p < .001.

TABLE 5
Comparison of the Nitrate, Chloride, and Total Dissolved Solids
(TDS) Concentrations in Two Successive Years for a Number of
Water Resources

                           Chemical Parameters
                           (Mean [+ or -] SD)

Year        Nitrate            Chloride                 TDS
            (mg/L)              (mg/L)                 (mg/L)

2012   5.04 [+ or -] 0.7   30.8 [+ or -] 5.6   209.20 [+ or -] 185.40
2013   6.7 [+ or -] 0.5    32.4 [+ or -] 6.7   335.36 [+ or -] 234.63
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Title Annotation:INTERNATIONAL PERSPECTIVES
Author:Nikaeen, Mahnaz; Shahryari, Ali; Hajiannejad, Mehdi; Saffari, Hossein; Kachuei, Zahra Moosavian; Has
Publication:Journal of Environmental Health
Geographic Code:7IRAN
Date:Jan 1, 2016
Words:4654
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