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Evaluation of Water Quality for Drinking and Irrigation Purpose from Simly Lake, Pakistan.

Byline: JAVED IQBAL, MUNIR HUSSAIN. SHAH, SYED AHMED TIRMIZI AND GULRAIZ AKHTER

Summary: Present study was carried out to assess the seasonal distribution of essential metals (Ca, K, Mg and Na) and physicochemical parameters (pH, T, DO, EC, TDS, TA, TH, Cl-, HCO[?], PS, SAR, RSBC and MAR) in freshwater samples of Simly Lake, Pakistan. The suitability of water for drinking and agricultural purpose was assessed using various water quality parameters and indices. The average concentrations for most of the studied parameters were found to be within the national/international guidelines. However, the levels of bicarbonate ion and residual sodium bicarbonate (RSBC) in the water were significantly higher than international standards. Irrigation water quality (IWQ) index revealed that the water was of medium level suitability for the irrigation purpose.

Keywords: water quality, physicochemical parameter, irrigation/drinking water, Pakistan.

Introduction

Water is an essential element for human life and access to freshwater in sufficient amounts and of suitable quality is a prerequisite to achieving sustainable development [1-3]. Freshwater comprises 3% of the total water on earth and only a small fraction (0.01%) of this freshwater is of good quality and available for human use [1, 4]. Unfortunately even this small percentage of freshwater is under massive stress due to rapid population growth, industrialization, urbanization and unsustainable consumption of water in industry and agriculture [1, 2]. According to World Health Organization, approximately 1.7 million deaths per year and about 50% mortality due to diarrheal disease among infants can be attributed to unsafe water supplies [5]. Surface water of the freshwater reservoirs is used for drinking water supply in most of the cities which discharge their untreated/treated municipal wastes into it [2].

The contamination of drinking water supply is becoming an increasingly serious problem and the maintenance of good quality water is indispensable to the protection of aquatic and terrestrial life and is directly linked to maintaining the biodiversity [3].

There is a dire need for the monitoring the surface water quality on regular basis for human beings and ecological vitality. Identification of the causes of declining water quality is obligatory for stumbling deterioration and implementing strategies for its improvement. Therefore, present study was conducted with following broad objectives; (1) to assess the seasonal variations in water quality of Simly Lake, (2) to compare the observed levels of the studied parameters with the corresponding international and national guidelines, and (3) to evaluate the water quality for drinking and irrigation purpose.

The physicochemical parameters measured during the present study included essential metals (Ca, K, Mg and Na), pH, temperature (T), dissolved oxygen (DO), total alkalinity (TA), electrical conductivity (EC), total dissolved solids (TDS), total hardness (TH), chloride (Cl-), bicarbonate (HCO[?]), residual sodium bicarbonate (RSBC), sodium adsorption ratio (SAR), percent sodium (PS), Kelly's ratio (KR), magnesium adsorption ratio (MAR) and permeability index (PI). It is anticipated that the study would provide a baseline data regarding the freshwater quality and it would be helpful in the management and control of the pollutants in the Lake.

Results and Discussion

The statistical summary related to the distribution of physicochemical parameters in the water samples during winter and summer is explicated in the Table-1. The suitability of water for drinking and irrigation uses depends upon its mineral constituents. The major quality criteria physicochemical parameters for drinking and irrigation purpose are pH, T, DO, TA, EC, TDS, TH, chloride ion, bicarbonate ion, sodium, potassium, calcium and magnesium, etc. The results pertaining to the essential metals revealed relatively higher contributions of Ca, followed by Na and Mg, whereas K was the least. Based on the average levels, the metals followed the decreasing concentration order in water during the both seasons: Ca (greater then) Na (greater then) Mg (greater then) K. The mean values of K, Mg and Na were found relatively higher during summer which may be due to the excessive leaching during wet season (summer).

The estimated levels of the metals were lower than the recommended national and international water quality guidelines [6-8], as shown in Table-1. It demonstrated that water was found to be of good quality for drinking purpose during both seasons.

The water quality may be assessed by determining its pH; it is considered acidic when pH is less than 6.50 or alkaline if pH is more than 8.50, both of which are non-desirable. However, the pH range from 6.50 to 8.50 indicates desirable water quality [8]. In the presents study, the pH values ranged from 6.93 to 8.27 and 7.37-7.66 with average values of 7.88 and 7.59 successively during winter and summer. Subsequently, the water was classified as desirable water category during both seasons. The estimated pH values were also within the permissible limits for drinking water as recommended by WHO, US-EPA and Pak-EPA (Table-1), demonstrating the suitability of water samples for the drinking purpose. On the average basis, pH was observed relatively higher during winter than summer which may be owing to the increase in carbonate and bicarbonate contents during dry season [9].

The dissolved oxygen (DO) contents of the water are influenced by the temperature, source, treatment and chemical or biological processes in the ecosystem. Depletion of DO in water can encourage the microbial reduction of nitrate to nitrite and sulfate to sulfide. It can also cause an increase in the concentration of ferrous ions in solution, with subsequent discoloration at the tap when the water is aerated [8]. A warm-water aquatic ecosystem should have DO concentrations of at least 5 mg/L in order to support the diversified benthic biota [10]. In the present study, the DO content varied from 5.87-6.61 and 4.12 to 4.56 mg/L with the average levels of 6.33 and 4.40 mg/L, respectively, during winter and summer. It indicated slight stress to the diversified biota during summer.

Alkalinity and calcium management contribute to the stability of water and control its aggressiveness to pipe and appliance. Failure to minimize corrosion can result in the contamination of drinking water and adversely affects on its taste and appearance [8]. The total alkalinity (TA) values ranged from 195 to 225 mg CaCO3/L and 131 to 153 mg CaCO3/L with the mean levels of 213 and 138 mg CaCO3/L, respectively, during winter and summer. Elevated TA values during winter may be associated with small storage capacity and reduced inflow of freshwater in the reservoir during dry winter conditions thereby manifesting higher concentrations of the ions responsible for the alkalinity. The ranges of EC values were 165-284 (mu)S/cm and 297-330 (mu)S/cm with the mean values of 265 and 312 (mu)S/cm during winter and summer, accordingly. These values were within the permissible limit for drinking as per international and national guidelines (Table-1), demonstrating the suitability of water for the drinking purpose.

Nonetheless, mean EC values were relatively higher during summer than winter which may be attributed to excessive leaching during wet season.

The suitability of water for irrigation was also assessed based on EC. It is a good measure of salinity hazard to crops as it reflects the soluble salts in the water. Excess salinity reduces the osmotic activity of plants and thus interferes with the absorption of water and nutrients from the soil. The water samples from the lake are classified as good water category (250 - 750 (mu)S/cm) for irrigation use [11]. To ascertain the suitability of water for drinking use, it is necessary to classify the water based on their TDS, which refer to any minerals, salts, metals, cations or anions dissolved in water. The TDS levels ranged as 92.5-192 mg/L and 150-163 mg/L with the mean values of 148 and 156 mg/L during winter and summer, respectively. The water contained low levels of TDS than the permissible limit for drinking as per international and national guidelines (Table-1) during the both seasons, indicating low content of soluble salts in the water which can be used for drinking without any risk.

The suitability of surface water for drinking purpose was also determined based on TH which ranged from 83.2-93.4 mg CaCO3/L and 83.2-115 mg CaCO3/L with the average values of 89.8 and 92.5 mg CaCO3/L, respectively, during winter and summer. The measured TH levels were observed to be within the permissible limit for drinking water as per WHO guidelines [8]. Generally, water is considered soft, moderately hard, hard and very hard with TH values (less then) 75, 75-150, 150-300 and (greater then) 300 mg/L, respectively. Consequently, the water samples from the lake were classified as moderately hard water during both seasons.

In irrigation water the chloride toxicity is most common. Chloride is not adsorbed or held back by soils, therefore, it moves readily with the soil- water, taken up by the crop, moves in the transpiration stream, and accumulates in the leaves. If the chloride concentration in the leaves exceeds the tolerance limit of the crop, injury symptoms develop such as, leaf burn or drying of leaf tissue. Normally, plant injury occurs first at the leaf tips and progresses from the tip back along the edges as severity increases. Excessive necrosis (dead tissue) is often accompanied by early leaf drop or defoliation [9]. Normally, Cl- (less then) 4 meq/L indicates no problem; Cl- = 4-10 meq/L reveals moderate problem; and Cl- (greater then) 10 meq/L shows severe problem. The chloride levels in water ranged from 0.310 to 0.518 meq/L and 0.490 to 0.700 meq/L with average levels of 0.426 and 0.577 meq/L during winter and summer, in that order.

As a result, the water samples during both seasons were categorized as 'no problem' water class for irrigation purpose with respect to chloride contents. Moreover, the chloride levels were within the permissible limit of international and national standards (Table-1), indicating that water was suitable for the drinking purpose during both seasons.

Irrigation water rich in bicarbonate content tends to precipitate insoluble calcium and magnesium in the soil as their precipitates which ultimately leave higher sodium proportion and increase SAR value [12]. It was also reported that although usual bicarbonate ion is not toxic, but it may cause zinc deficiency in crops; severe when it exceeds 2 meq/L in water for irrigation use [9]. The bicarbonate contents ranged from 3.9-4.5 meq/L and 2.64-3.04 meq/L having average levels of 4.26 and 2.78 meq/L during winter and summer, respectively. Therefore, the water samples were classified as unsuitable for irrigation purpose with respect to bicarbonate contents during both seasons. The positive RSBC values indicated that dissolved calcium and magnesium ions are less than those of carbonate and bicarbonate contents. The RSBC values in water samples varied as 2.88-3.67 meq/L and 1.37-2.16 meq/L with average values of 3.31 and 1.87 meq/L, successively, during winter and summer.

Accordingly, the water was graded as unsuitable for irrigation purpose in relevance to RSBC [13].

Water suitability for irrigation use was also determined based on SAR. It is an important parameter and a measure of alkali/sodium hazard to the crops. It can indicate the degree to which irrigation water tends to enter into cation-exchange reactions in the soil. Sodium replacing adsorbed calcium and magnesium is a hazard as it causes damage to the soil structure which becomes compact and impervious. The SAR values varied from 0.654 to 0.734 and 0.589 to 0.735 with the average values of 0.684 and 0.692, respectively, during winter and summer. SAR (less then) 10, indicates excellent water; SAR = 10 - 18, indicates good water; SAR = 18 - 26, indicates doubtful water; and SAR (greater then) 26, demonstrates unsuitable water [14]. The water samples were, therefore, classified as excellent water for irrigation which implies that no alkali hazard was anticipated to the crops with the water during both seasons.

Sodium concentration is important in classifying irrigation water because sodium reacts with soil to reduce its permeability. When sodium concentration is high in irrigation water, it tends to be absorbed by clay particles, displacing calcium and magnesium, thus reduces the permeability resulting in restricted air and water circulation during wet conditions. The PS values ranged as 27.5-29.7 % and 24.5 to 31.2 % with the mean values of 28.6 and 29.2%, respectively, during winter and summer. Based on PS, the water is classified as; PS = 0 - 20% indicates excellent water; PS = 20 - 40% indicates good water; PS = 40 - 60% shows permissible water; PS = 60 - 80% shows doubtful water and PS (greater then) 80% demonstrates unsuitable water [11]. Accordingly, the water samples during both seasons were classified as good water for agricultural use.

The water samples were also classified for irrigation purpose based on the Kelly's Ratio (KR). Sodium measured against calcium and magnesium was considered by Kelly [15] to calculate this parameter. A Kelly's Ratio of more than one indicates an excess level of sodium in water, while, water with a KR value less than one is suitable for irrigation. The KR ranged from 0.342-0.384 and 0.281-0.396 with average values of 0.361 and 0.360, during winter and summer. As a result, the water was classified as suitable water for irrigation use.

Generally, calcium and magnesium maintain a state of equilibrium in most water ecosystems. In equilibrium more Mg in the water may adversely affect crop yields. At the same level of salinity and SAR, adsorption of sodium by soils and clay minerals is more at higher Mg/Ca ratios. This is because the bonding energy of magnesium is less than that of calcium, allowing more sodium adsorption which predominates when the ratio exceeds 4 [12]. It was also reported that soils containing high levels of exchangeable magnesium causes infiltration problem [9]. Based on Mg/Ca, the waters are classified as suggested by Kumar et al., [16]. Mg/Ca (less then) 1.5 indicates safe; Mg/Ca = 1.5-3.0 reveals moderate; and Mg/Ca (greater then) 3.0 shows unsafe water class. The Mg/Ca ratios were registered as 0.806-1.01 and 0.695-1.34 with mean values of 0.891 and 1.06 during winter and summer, respectively. Thus, the water samples were categorized as 'safe' water class during both seasons.

Table-1: Statistical summary for the distribution of physicochemical parameters in water samples during winter and summer in comparison with national/international guidelines.

###Winter (n = 50)###Summer (n = 50)

###Range###Mean###Median###SE###Skew###Range###Mean###Median###SE###Skew###WHO [18]###USEPA [17]###PakEPA 1161

Ca (mg/L)###16.6-20.6###19.1###19.4###0.186###-0.570###14.3-27.9###18.1###18.0###0.366###1.91###100###-###200

K (mg/L)###2.49-3.36###2.71###2.69###0.025###2.85###3.37-4.71###3.87###3.87###0.048###0.64###12###-###-

Mg (mg/L)###9.96-10.9###10.3###10.2###0.038###1.29###10.8-11.7###11.5###11.5###0.042###-1.23###50###-###-

Na (mgIL)###14.5-15.8###14.9###14.8###0.054###0.847###12.5-16.2###15.3###15.7###0.144###-1.59###200###-###-

pH###6.93-8.27###7.88###7.99###0.066###-0.984###7.37-7.66###7.59###7.59###0.011 -0.932###6.5-8.5###6.5-8.5###6.5-8.5

T (degC)###10.1-10.3###10.2###10.2###0.009###0.200###26.5-56.8###26.7###26.7###0.014 -0.947###-###-###-

DO (mg/L)###5.87-6.61###6.33###6.35###0.028###-0.942###4.12-4.56###4.40###4.41###0.022 -0.183###-###-###-

TA (mg CaCO3/L)###195-225###213###210###1.382###-0.595###131-153###138###141###0.775###0.415###200###-###-

EC ((mu)S/cm)###185-384###295###292###3.870###-3.12###297-330###312###307###1.48###0.801###1500###-###-

TDS (mg/L)###92.5-192###148###146###1.527###-3.10###150-163###156###155###0.738###0.733###1000###500###1000

Cl- (mg/L)###11.1-18.4###15.1###14.7###0.270###-0.267###17.4-24.8###20.5###19.9###0.389###0.025###250###250###250

HCO3- (mg/L)###238-275###260###256###1.69###-0.595###161-185###170###171###0.946###0.42###-###-###-

TH (mg CaCO3/L) 83.2-93.4###89.8###90.2###0.457###-0.897###83.2-115###92.5###91.7###0.946###1.74###500###-###-

RSBC (meq/L)###2.88-3.67###3.31###3.33###0.028###-0.431###1.37-2.16###1.87###1.89###0.022###-1.37###-###-###-

SAR###0.654-0.734###0.684 0.684###0.003###0.184 0.589-0.735###0.692###0.705###0.007###-1.25###-###-###-

PS (%)###27.5-29.7###28.6###28.5###0.113###0.191###24.5-31.2###29.2###29.4###0.248###-1.28###-###-###-

KR###0.342-0.384###0.361 0.361###0.002###0.149 0.281-0.396###0.360###0.364###0.004###-1.21###-###-###-

Mg/Ca###0.806-1.01###0.891 0.867###0.010###0.525###0.695-1.34###1.06###1.05###0.019 -0.332###-###-###-

MAR###44.6-50.2###47.1###46.4###0.283###0.462###41.1-57.2###51.2###51.3###0.469###-1.10###-###-###-

PI (%)###104-126###114###113###0.730###0.304###68.2-90.3###81.8###81.9###0.613###-1.18###-###-###-

DO-Dissolved Oxygen; TA-Total Alkalinity; EC-Electrical Conductivity; TDS-Total Dissolved Solids; TH-Total Hardness; Cl--chloride ion; HCO [?] - bicarbonate ion; RSBC-Residual Sodium Bicarbonate; SAR-Sodium Adsorption Ratio; PS-Percent Sodium; KR-Kelly's Ratio; MAR-Magnesium Adsorption Ratio; PI-Permeability Index

Paliwal [17] introduced an important ratio called Magnesium Adsorption Ratio (MAR) to assess the water for irrigation purpose. Magnesium ratios of more than 50% would adversely affect the crop yield as the soils become more alkaline. The water samples during winter and summer contained the average values of 47.1 and 51.2%, respectively, indicating unsuitability of water for irrigation use.

Permeability problem occurs when normal infiltration rate of soil is appreciably reduced and hinders the moisture supply to crops which is responsible for two most water quality factors as salinity of water and its sodium content relative to calcium and magnesium. The soil permeability is affected by long-term use of irrigation water and is influenced by sodium, calcium, magnesium and bicarbonate contents of the soil. Doneen [18] evolved a criterion for assessing the suitability of water for irrigation based on PI. According to PI values, the water samples can be classified as Class I, Class II and Class III. Class I and Class II water samples are categorized as good for irrigation with 50-75% or more of the maximum permeability. Class III water samples are unsuitable with 25% of the maximum permeability. The permeability index of water samples during winter and summer varied from 104-126 % and 68.2-90.3 % with the mean values of 114 and 81.8%, respectively.

Accordingly, the water fell into the Class I and II category of the Doneen's chart during both seasons.

Irrigation water quality (IWQ) index is an integrated method that is based on the linear combination of the five different groups of irrigation water quality parameters that have potential negative impacts or hazards on soil quality and crop yield. In this index, all five groups are simultaneously included in the analysis and are combined to form a single index value, which is then assessed to determine the suitability of the irrigation water. The water quality parameters from these groups are selected based on the guidelines presented by Ayers and Westcot [9]. These parameters not only best characterize the associated hazard but also combine with others to form a general pattern of water quality for the particular resource. Furthermore, these parameters are arranged such that the results obtained from this tool would make sense to a non-technical decision maker that could use the method without difficulty.

The IWQ index uses EC to represent the salinity hazard; EC and SAR are assessed together to represent the infiltration and permeability hazard; chloride and sodium (SAR) to represent the specific ion toxicity; linear combination of trace metals to represent the trace metals toxicity; and linear combination of bicarbonate and pH to represent miscellaneous effects to sensitive crops. In the proposed tool, each one of these parameters is given a weighing coefficient from 1 to 5 (Table-2). In addition to the weighing coefficients, the technique also assigns rating factors for each parameter as shown in Table-2. The proposed IWQ index is then calculated as:

Table-2: Classification for irrigation water quality (IWQ) index parameters.

###Hazard###Weight###Parameters###Range###Rating###Suitability

###EC(less then)700###3###High

Salinity hazard###5###Electrical Conductivity (pS/cm)###700 [?] EC [?] 53000###2###Medium

###EC (greater then) 3000###1###Low

###SAR

###(less then) 3###3-6###6-12###12-20###(greater then) 20

Infiltration and Permeability hazard###4###(greater then) 700 (greater then) 1200 (greater then) 1900 (greater then) 2900 (greater then) 5000###3###High

###EC 700-200###1200-300###1900-500###2900-1300###5000-2900###2###Medium

###(less then) 200###(less then) 300###(less then) 500###(less then) 1300###(less then) 2900###1###Low

###SAR (less then)3.0###3###High

###Sodium adsorption ration (SAR)###3.0 [?] SAR [?] 9.0###2###Medium

###SAR(greater then)9.0###1###Low

Specific ion toxicity###3###Cr (less then) 140###3###High

###Chloride (mg/L)###140 [?] Cl- [?] 350###2###Medium

###ND###Cl- (greater then) 350###1###Low

Trace element toxicity###2

###HCO3- (less then)90###3###High

###Bicarbonate (mg/L)###90 [?] HCO3 [?]###2###Medium

###500

Miscellaneous effects to sensitive crops###1###HC03 (greater then) 500###1###Low

###7.0 [?] pH [?] 8.0###3###High

###6.5 [?] pH (less then) 7.0 and###2###Medium

###pH###8.0 (less then) pH [?] 8.5###1###Low

ND - Not Determined

where, i is an incremental index and G represents the contribution of each one of the five hazard categories that are important to assess the quality of an irrigation water resource. The first category is the salinity hazard that is represented by the EC value of the water and is formulated as:

where, w is the weight value of this hazard group and r is the rating value of the parameter as given in Table-2. The second category is the infiltration and permeability hazard that is represented by EC-SAR combination and is formulated as:

where, w is the weight value of this hazard group and r is the rating value of the parameter as given in Table-2. The third category is the specific ion toxicity that is represented by SAR and chloride ion in the water and is formulated as a weighted average of the two ions:

where, j is an incremental index, w is the weight value of this group and r is the rating value of each parameter as given in Table-2. The fourth category is the trace element toxicity that is represented by the

metals which were not determined in the present study and is formulated as a weighted average of all the metals available for analysis:

where, k is an incremental index, N is the total number of trace metals available for the analysis, w is the weight value of this group and r is the rating

value of each parameter as given in Table-2. The fifth and the final category is the miscellaneous effects to sensitive crops that is represented by bicarbonate ion and the pH of the water, and is formulated as a weighted average:

where, m is an incremental index, w is the weight value of this group and r is the rating value of each parameter as given in Table-2.

After the total value of the index is computed, a suitability analysis is done based on the three different categories as suggested by Simsek and Gunduz [19]. IWQ (less then) 22, indicates low suitability of water; IWQ = 22-37, demonstrates medium suitability of water; and IWQ (greater then) 37, shows high suitability of water for irrigation. When the computed index value is higher than 37, the corresponding area is considered to have minimum problems with respect to irrigation quality. When the computed index value is between 22 and 37, the corresponding water demonstrates moderate suitability for irrigation purposes. Within this range, values higher than 30 are considered to represent water that could be easily used on resistant crops. These water samples generally obtain high scores from the most important parameters including salinity hazard and infiltration and permeability hazards.

On the other hand, values below 30 indicate water that should only be used with caution and better be avoided, particularly for sensitive crops, if a better alternative is present. These areas generally have low scores from the most important parameters including salinity and infiltration hazards. Under extreme conditions, water from these locations could be used with caution. Finally, areas with IWQ index values of less than 22 are considered to be poor quality irrigation water and are not suitable for irrigating agricultural fields. Such water samples could impair soil quality and result in yield loss. As a rule of thumb, water from such areas should be avoided. According to the overall index map, it could be mentioned that the water samples from the lake demonstrated medium level suitability (IWQ index = 22-37) for irrigation use during winter and summer.

However, there are several factors that may deteriorate this status including the intrusion of agricultural run-off and the uncontrolled sewage disposal from the residential areas. The IWQ index is believed to be a suitable tool for agricultural management plans and in determining the most suitable site for assessing the overall water quality.

Experimental

Study Area

Simly Lake (longitude: 73o20'E and latitude:

33o43'N) is a freshwater source reservoir for the inhabitants of Islamabad, Pakistan (Fig. 1). It is an 80 meters high, earthen embankment reservoir on the Soan River, near Bhara Kahu town, 30 km in the east of Islamabad. It was built in 1983 and is extended over an area of 28,750 acres. The water coming from snow melting and natural springs of Murree hills is stored in the Lake. It is also a picnic spot because of its scenic location. The Lake endows with recreation facilities like boating, sailing, fishing and water skiing. Untreated wastewater, industrial effluents, runoff from poultry farms and pollutants released during the recreational use of motorboats are among the major contamination sources in the Lake.

Sample Collection and Analysis

Triplicate water samples were collected in pre-cleaned and dried high density polyethylene bottles (1.5 L) from Simly Lake during winter and summer 2009, following the standard procedure [20]. The sampling bottles were kept in airtight large plastic containers and were transported to laboratory within 6 h of their collection for further processing [21]. Each water sample was divided into two parts: one part was filtered to remove any suspension and thereafter was used for the measurement of physicochemical parameters without addition of any chemical reagent, while second part was preserved by acidifying with concentrated nitric acid (AR grade) to pH (less then) 2 for the metal analysis [22]. The physicochemical parameters (pH, DO, EC and TDS) were determined immediately after the sample collection [10, 20].

During the present study, pH was measured using a digital pH meter (Model: Martini Mi 180, Romania); DO was estimated by utilizing a digital DO meter (Model: Martini Mi190, Romania); EC and TDS were measured by a digital conductivity meter (Model: Jenway 470, EU). Chloride contents (Cl-) and total alkalinity (TA) were determined following the standard methodology [10, 20]. Essential metals (Ca, K, Mg and Na) in water samples were analyzed using flame atomic absorption spectrophotometry (Shimadzu AA-670, Japan) under optimum analytical conditions, employing the calibration line method [23, 24]. A reagent blank was processed in the same manner along with each batch of the samples. Standard reference material (SRM 1643d) was also used to ensure the reliability of the metal data. All the measurements were made in triplicate. Analytical grade chemicals were used throughout the study. To prepare all the reagents and working standards, distilled water was used.

The metal standards (E- Merck, Darmstadt, Germany) were prepared from stock solution of 1000 mg/L by succeeding dilutions.

Statistical Analysis

Statistical methods were applied to treat the analytical data in terms of their distribution and interrelationships among the studied parameters using STATISTICA software. Basic statistical parameters such as, range, mean, median, standard error (SE) and skewness were calculated [23, 24]. Other physicochemical parameters including total hardness (TH), residual sodium bicarbonate (RSBC), percent sodium (PS), sodium adsorption ratio (SAR), magnesium adsorption ratio (MAR), Kelly's ratio (KR), and permeability index (PI) were calculated from ionic concentrations (meq/L) of Ca, Mg, Na, HCO [?] and K using the following relationships [13, 15, 18, 25]:

Conclusions

In conclusion, the present study demonstrated divergent variations of the physicochemical parameters in the water samples from freshwater Simly reservoir. In comparison with national and international guidelines, the measured levels of essential metals were found to be lower. The suitability of water for drinking and irrigation uses was also assessed by the physicochemical parameters, which mostly manifested safe and acceptable water for drinking and irrigation purposes, however, the water were unsuitable for irrigation purpose with respect to bicarbonate content, RSBC and MAR. The IWQ index evidenced that the water was of medium level suitability for the agricultural use.

Acknowledgement

The financial assistance provided by Quaid- i-Azam University, Islamabad, Pakistan to carry out this project is thankfully acknowledged.

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1Department of Chemistry, Quaid-i-Azam University, Islamabad 45320, Pakistan.

2Department of Earth Sciences, Quaid-i-Azam University, Islamabad 45320, Pakistan. mhshahg@qau.edu.pk, munir_qau@yahoo.com
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Author:Iqbal, Javed; Hussain, Munir; Tirmizi, Syed Ahmed; Akhter, Gulraiz
Publication:Journal of the Chemical Society of Pakistan
Article Type:Report
Geographic Code:9PAKI
Date:Dec 31, 2012
Words:5463
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