ISSN 0976-2612, Online ISSN 2278–599X, Vol-7, Special Issue-Number4-July, 2016, pp776-783
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Research Article
Study of Babolrood River`s WQI in Mazandaran province, Iran
Ali Behmanesh
Department of Environmental Sciences, Islamic azad University,
Qaemshahr Branch, Qaemshahr, Iran
Email:[email protected]
ABSTRACT
Water quality parameters of 7 different water stations along the Babolrood River were collected to determine its water quality according to water quality index(WQI).Six most important parameters pH, total dissolved solids, dissolves oxygen, biochemical oxygen demand, electrical conductivity and temperature difference were considered for WQI. The WQI was assessed using a weighted arithmetic index method and National Sanitation Foundation method (NSF). According to the arithmetic mean method WQI valuesvary between 38 and 88, wherein NSF Method WQI values vary between 48 and 80. Inweighted arithmetic index method highest favorable value gives a low statistical value to theindex whereas lowest favorable value gives statistical value to the index in NSF method. The values of the WQI showed that the water of the maximum stations are poor and very poor in condition, few of them can be referred to as good, and among all water stations only one of the stations Id(S1) contains good water quality parameter for human consumption and other uses. The results revealed that although WQI of most of the stations are beyond acceptable limit but could be used for domestic and household purpose after purification.
Keywords: Water Quality Index,Babolrood River,DissolvedOxygen,Biochemical Oxygen Demand, Total Dissolved Solids.
1.0
INTRODUCTION
Water is a unique resource because is essential for all life and it constantly cycles between the land and the atmosphere. The same water that is used for crop and animal production can also be shared with the public and the aquatic and terrestrial ecosystems (Cooperetal.,1998).Water resources are of great environmental issues and studied by a wide range of specialists including hydrologists, engineers, ecologists, geologists and geo morphologists (Kumar andDua,2009).It has become an important issue for them as it affects not only human uses but also plant and animal life. For healthy living, potable safe water is absolutely essential. It is a basic need of all human being to get the adequate supply of safe and fresh drinking water.
One of the most effective ways to communicate
instrument used to transform large quantities of water quality data into asingle number which represents the water quality level while eliminating the subjective assessments of water quality and biases of individual water quality experts. Basically a WQI attempts to provide a mechanism for presenting accumulatively derived, numerical expression defining a certain level of water quality (Milleretal.,1986). Comparison can be made through the WQI among the water bodies and a general analysis of water quality on different levels can be made. A water quality index is a means to summarize large amounts of water quality data into simple terms (e.g.,poor, good etc.) for reporting to management and the public in a consistent manner.
Importance of rivers evident in terms of water quality, biodiversity conservation and use for aquaculture, as maximum of the water bodies of Iran, as well as Mazandaran province are expected to be productive. So utilization of the existing resources is very much vital. In the way to improving the condition of these water resources, its proper management is very much necessary and for doing this all information on the resources namely physico-graphic, chemical and biological characteristic of these water resources must be collected. The objective of this paper is to determine the WQI of 7stations in Babolrood River. Drinking water contamination and variation of drinking water quality in during months of year especially in dry season is the basis of calculated values of WQI as concentrations of different water quality parameters tend to be at its worse condition during dry season. Based on the WQI an assessment was made whether Babolrood River water quality in various stations are acceptable for various purposes as agriculture, domestic use and even for drinking uses. Local people living along Babolrood River are completely dependent on this river water as there is no proper water supply made to meet their needs, especially for paddy fields irrigation. For this reason, this analysis is extremely necessary so that people living in these areas can markout the best water source available. Similar type of studies have been
done in Iran by Nasrollahi Harikanki (2005) by using the data of three surveying stations affiliated to Environment Protection Office made the qualitative modeling of the water by using quar2e software, and showed that, due to the much density of residential areas and much water contamination, self refining is not suitable. He suggested that the model be made with more and more various stations. Also Ghanbari and Moradi (2003), by selecting 3 stations in the Babol River from 2001 to 2003, surveyed different biological, chemical and physical parameters seasonally, and by comparing the average of parameters in different stations studied the process of the change. But this study has its individual significance as WQIvaluesof7 stations were taken along Babolrood River length of a specific region from Quran Talar, after Alborz Dam site in upstream to Babolsar where the river water discharge into Caspian Sea, in Mazandaran province, Iran.
2.0 STUDYAREAAND METHODOLOGY
The present study was conducted along the Babolrood River, one of the most important rivers of Mazandaran province in North of Iran which is of about 120 km in length. This River originates from Alborz mountain in south of Babolcounty by joining of three main tributaries namely- Azarrood,Karsangrood and Esklimrood.The parameters- water temperature, pH, dissolved oxygen (DO),total dissolved
solids (TDS) and electrical
methods presented in the standard method. For BOD measurement, a 500ml bottle was used for collection of water samples and the oxygen was fixed at the sampling site before being carried to the laboratory for further analysis.
The temperature of the water has been measured by mercurial thermometer at the sampling place, and for measuring other parameters, the water samples have been sent to the laboratory.
Figure1: Index map of studyarea
The examination and analysis of the catched water samples of Babolrood River in selected stations including laboratory analysis was done as per the standard methods. The calculation of WQI was made using weighted arithmetic index method (Brownetal.,1972) and National
Sanitation Foundation method. Finally assessment of Babolrood river water quality based on water quality index was done. Table 1 shows the details of analysis methods and necessary equipments used in the study.
Table1: Details of physic-chemical parameters, analysis methods and the equipments.
Serial Number Temperature Methodology Equation
1 Temperature Visible Centigrade Thermometer 2 Salinity Visible EC Meter with Thermometer 3 pH Visible METROH632( PH moter ) 4 Transparency Visible Turbidity Meter 5 Dissolved Oxygen Visible DissolvedOxygenMeter(hack) 6 BOD Laboratory DissolvedOxygenMeter
8 TDS Visible Weight method
3.0 WQICOMPUTATION EQUATIONS
The calculation of WQI, selection of parameters has great value. The water quality index will widen if too many parameters are
foundation method. Five physico- chemical parameters namely pH, TDS, EC, DO, BOD were used to calculate wqi by the weighted arithmetic index method. Several steps of weighted arithmetic index method are given (brownetal.,1972) in the following steps:
3.1 Calculation of Sub Index of Quality Rating (qn)
Let the reben water quality parameters where the quality rating or subindex(qn)corresponding to the nth parameter is a number reflecting the relative value of this parameter in the polluted water with
respect to its standard permissible value. The value of qn is calculated using the following expression.
qn = 100[(Vn- Vio) /(Sn - Vio)] (1) Where,
qn = quality rating for the nth water quality parameter.
Vn=estimated value of the nth parameter at a given sampling station.
Sn = standard permissible value of nth parameter
Vio= ideal value of nth parameter in pure water.
All the ideal values(Vio)are taken as zero for drinking water except for pH=7.0and dissolved oxygen=14.6mg/L.(TripatyandSahu,2005).
3.2 Calculation of Quality Rating for pH
For pH the ideal value is 7.0(for natural water) and a permissible value is
8.5(forpollutedwater). Therefore, thequality rating for pHiscalculatedfromthe following relation:
qpH =100[(VpH -7.0)/(8.5 -7.0)] (2) Where,
VpH = observed value of pH duringthe study period.
3.3 Calculation of QualityRating for Dissolved Oxygen
Theidealvalue(VDO)fordissolvedoxygenis14.6 mg/Landstandardpermittedvaluefordrinkingwat er is 5 mg/L.
Therefore, qualityrating is calculatedfromfollowing relation:
qDO =100[(VDO - 14.6)/(5 –14.6)] (3) Where,
VDO = measured value of dissolved oxygen
3.4 Calculation of Unit Weight(Wn)
Calculation of unit weight(Wn)for various water quality parameters are inversely proportional to the
recommended standards for the corresponding parameters.
Wn =K/Sn
Wn =unit weight for nth parameters Sn= standardvalue for nthparameters K=constant for proportionality
3.5 Calculation of WQI
WQI is calculated from the following equation:
n n
WQI =∑ qn Wn /∑Wn (5)
n=1 n-1
3.6 Calculation of WQI by NSF method
The NSF water quality index was developed by the National Sanitation Foundation (NSF) in 1970. An equation of NSF water quality index was found by using weighted factor of individual parameter and sub- index of each water quality parameter based on their respective testing values which can be found by water quality index calculator or water quality index curve of respective parameters.
The water quality index of individual parameter was calculated from water quality index calculator used by Environmental Engineering and Earth Sciences, Center of Environmental Quality, Wilkes University (Islamet al.,2011). WQI = 0.17IDO+ 0.11IpH + 0.10IΔT+ 0.07ITDS
4.0 RESULTSOF SUB-WATER QUALITY INDEX
Subwater quality index of five parameters for the former method (Brown arithmetic mean method)are given in
Table 2 and Sub water quality index of four parameters by the NSF method are given in Table 3.
Method.
Station
Subwater quality Index
(pH)
Subwaterquality Index
(TDS)
Subwaterquality Index
(EC)
Subwaterquality Index
(BOD)
Subwaterquality Index
(DO)
S1 4.974 0.278 0.073 4.612 26.824
S2 20.046 0.229 0.060 17.680 35.232
S3 15.073 0.117 0.031 15.374 40.437
S4 7.536 0.083 0.022 23.830 41.638
S5 0.301 0.148 0.039 29.979 45.641
S6 7.536 0.159 0.042 26.136 50.446
S7 1.507 0.410 0.107 6.150 48.444
4.1 pH
pH is one of the most important factors that serves as an index for the pollution.The highest value of pH was 8.7 at S3 and lowest was 7.7 at S5. A pH between 6.7 and 8.4 is suitable, while pH below 5.0 and above 8.3 is detrimental. Maximum Subwater quality index for pH was found 20.046 at S2 station and Minimum was found as 0.301 at station S5 according to Brown’s method. The maximum and minimum values are 93 (S1,3,4,6) and72 (S2) respectively.
Table3:Subwater quality Index of the physico-chemical parameters according to NSF Method.
Station SubwaterqualityIndex (pH)
SubwaterqualityIndex (TDS)
SubwaterqualityIndex
(ΔT)
SubwaterqualityIndex (DO)
S1 93 52 88 99
S2 72 60 74 87
S3 93 75 89 75
S4 93 83 84 45
S5 88 74 87 30
S6 93 72 85 15
S7 90 20 84 20
4.2 Total Dissolved Solids
The TDS level found to fluctuate from 290mg/l to 370mg/l within the Babolrood River in dry season. The TDS content was maximum in S7 and minimum in S4 with average of 339.523 mg/l. The amounts of total solids are influenced by the activity of the plankton and organic materials. Water containing more than 500mg/L of TDS is not considered desirable for drinking water supply. Maximum Sub water quality index for TDS is found close to 1 at S7 station and Minimum Sub water quality index for TDS was found almost 0at1stations (Brown Method). Maximum Subwater quality index for TDS is found 83(Station4) and minimum Subwater quality index for TDS was found as 20(Station 7). (NSFmethod)
4.3 Dissolved Oxygen
The value of DO varied from4mg/l to8.1mg/l. The maximum DO value (8.1mg/l) was
recorded inS1 and minimum value (4mg/l) was recorded inS6. The mean value of DO was 5.4mg/l. Concentrations below 5 mg/L may adversely affect the performance and survival of biological communities and below 2 mg/L may lead to fish mortality. Water without adequate DO may be considered waste water. Maximum Subwater quality index for DO was found 50.5 at S6 and minimum subwater quality index for DO was found 26.8 at S1 (BrownMethod). Maximum Subwater quality index for DO was found 99 at (S1) and minimum subwater quality index for DO was found15atS6.
4.4BiochemicalOxygen Demand
Minimum Subwater quality index for DO was found 4.612 at P-5 (Brown Method).
4.5 Electrical Conductivity
Conductivity is measured interms of conductivity per unit length, and meters typically use the unit micro
Siemens/cm. The values of water conductivity varied from727.7 µs /cm to 1691 µs/cm among the stations in dry season. The value of conductivity was recorded lowest in S4 and
maximum in S7.Themeanvalue was
832.7µs/cm.Sub water quality index for Electrical Conductivity is almost 0 at all stations (Brown Method).
4.6 Temperature Difference
Surface water (ambient air)temperature varied between17˚Cand34.5˚C and water temperature varied between 17.5˚C and 32˚C.Maximum difference in temperature was 7˚C and minimum was 0.5˚C, and the average difference was3.6˚C.Maximum Subwater quality index of temperature difference is 89 at station S3, and the minimum was at S2and the value was 74.
5.0 ASSESSMENT OF WATER QUALITY
WQI has been classified into 5classes.Table4 and Table 5 represents the 5classes of water quality based on WQI of two methods respectively.
Table4:Status of water quality based on Arithmetic WQI method (Brown etal.,1972)
Water quality
index Status
0-25 Excellent
26-50 Good
51-75 Poor
76-100 Very poor
Above100
Unsuitable for drinking and propagation of fish culture
Table5:Status of water quality based on National Sanitation Foundation WQI
Water quality index Status
0-25 VeryBad
26-50 Bad
51-75 Medium
76-100 Good
Above100 Excellent
The observed range of water quality index along the Babolrood River is 41 to91 by the arithmetic mean method. Maximum WQI was91at station7andminimum is 38 at station1.Only one single station’s water quality can be expressed as good(1).
S2 ,S3 ,S4 ,S5 have been classified as poor water. Rest of the stations S6,S7 have been classified as containing very poor water, but all of them can be used for domestic purpose by taking proper disinfection procedure. Stations with WQI values more than90 can be classified as unsuitable for both domestic and aquaculture purposes. 1 of the stations turned out to be unsuitable as WQI value is more than90. According to the NSF, WQI varied between 48 and 80. As the lowest value indicates the best value most of the water stations fall within medium to good water quality range. Among the stations2,3,4,5 have been classified as medium water And one of the stations water( 1 ) has been classified as good water. There is a little difference in categorization of the stations according to the two methods as the parameters selected for the methods are different and this is because of the unavailability of the parameters. One point is notice able that according to the arithmetic mean method by brown WQI ranges from51-75has been classified as poor where according to NSFWQIth is range has been classified as medium. So it will be better to count acceptable range between 0-50 for Browns method and 75-to more than 100 for the NSF method.
Table.3shows the WQI values of the 7 stations measured in during 1 year period(2008-2009). Station S1 can be classified as the best stations among all.
Table6 represents WQI value of the7 stations by two methods. Table 7 represents the maximum, minimum and average value of different parameters.
Station* Name of Station Waterquality
index (weighted arithmetic index)
Waterquality index (National
Sanitation FoundationWQI)
Description
S1
Quran Talar 38 80 Good
S2 Anarestan 73 75 Poor/Medium
S3
Mohammad Hassan khan
bridge
71 73 Poor/Medium
S4
Kharoun 73 70 Poor/Medium
S5
Habibi bridge 76 63 Poor/Medium
S6
Amirkola 83 50 Very poor/Bad
S7 Bablsar 88 48 Very poor/Bad
Table7:Maximum, minimum and average values of different water quality parameters during dry season
Groups Maximum Minimum Average
pH 8.7 7.6 8.3
DO(mg/l) 7.1 2.6 4.89
BOD(mg/l) 3 0.4 1.52
Conductivity(2ms) 1691 175 832.7
TDS 370 290 339.523
Air Temperature 34.5 17 24.38
Water Temperature 32 17.5 24.11
Table8: Drinking water standards and unit weight
Parameter Recommending
Agency
Standard value (S)
Ideal value
1/S Assigned
Weighted factor
pHH DOE 6.5-8.5 7 0.117647 0.226087822
TDS WHO 500 0 0.002 0.003843493
EC WHO 1400 0 0.000714 0.001372676
DO WHO 5 14.6 0.2 0.384349297
BOD ICMR 5 0 0.2 0.384349297
K 0.52036 1
6.0 CONCLUSION
WQI have some margins as it may not carry enough information about the actual situation of the water bodies. Also many other use sofwater quality data cannot be met with an index. Despite of having such problem WQI are more recompense than its draw back. WQI of the stations along the Babol rood Riverfora year period study(2008-2009)was found fairly high according to the Brown method, as concentration of water quality parameters are maximum during dry season and due to the same reason according to NSF method the values were low. In accordance with Brown method it is found from the calculation that parameter which shows the highest favorable value gives a low statistical value to the index
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