Assessment of Water Quality Index of River Salandi at Hadagada Dam and Its Down Stream upto Akhandalmani, Bhadrak, Odisha, India

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Map 1. Location of sampling stations across river Salandi

2.2. Analysis of Physico-Chemical Parameters

Further the water samples which are collected in well cleaned plastic bottles by adding about to 2 ml conc. HNO₃ in each bottle (to avoid the precipitation of metals) have been analyzed to study the physico-chemical & bacteriological parameters according to the method APHA, prescribed in 1995 ^[24]. TDS was measured by gravimetric method & total hardness was measured by complexometric method by using EDTA solution with eriochrome black-T as indicator and calcium content was determined by EDTA with murexide as indicator. Sulphate was measured by turbidimetry method & iron was measured by using phenanthroline as indicator with the help of spectrophotometer at 510 nm. Total chromium & nitrate were measured by spectrophotometer at 540 nm & 275 nm respectively ^[1].

2.3. Fluoride, Chloride & Bacteria

The fluoride was determined by using SPAND reagent & acid zirconium chloride by spectrophotometer at 570 nm ^{[22, 23]}. Chloride & bacteria were determined by titration method & H2S kit method respectively ^[1]. The analysis results of the months April, May, August, October & December have been reported in Table 2, Table 3, Table 4, Table 5 & Table 6 respectively. Finally mean values of twelve important parameters of nine monitoring stations have been placed in Table 7 for computation of water quality index.

Table 2. WATER ANALYSIS REPORT OF RIVER SALANDI IN APRIL 2015 Unit - except pH all concentrations are expressed in mg/L

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Table 3. WATER ANALYSIS REPORT OF RIVER SALANDI IN MAY 2015 Unit - except pH all concentrations are expressed in mg/L

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Table 4. WATER ANALYSIS REPORT OF RIVER SALANDI IN AUGUST 2015 Unit - except pH all concentrations are expressed in mg/L

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Table 5. WATER ANALYSIS REPORT OF RIVER SALANDI IN OCTOBER, 2015 Unit - except pH all concentrations are expressed in mg/L

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Table 6. WATER ANALYSIS REPORT OF RIVER SALANDI IN DECEMBER,2015 Unit - except pH all concentrations are expressed in mg/L

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Table 7. MEAN Values for twelve important parameters, 2015

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Table 8. water quality index of sampling station hadagada, 2015

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2.4. Water Quality Index

Water quality index is a modern method that depicts the whole water quality of any water body through a single number, developed by considering the combined effect of important physico-chemical parameters. In the present study, weighted Arithmetic Index method²⁶ has been used preferably to calculate Water Quality Index of the river Salandi due to following reasons:

i) It classifies the water quality of any water body according to degree of purity by using most commonly measurable parameters and it is widely used by the different scientists, workers and organisations ^{[5, 38, 39, 40, 41, 42]}.

ii) It reflects overall effects of different parameters for better assessments and managements of water quality of any water body under study.

iii) Less number of parameters are required in comparison to other methods.

iv) It reflects the suitability of both surface and ground water sources for human consumption ^[43].

This method includes following steps which is explained briefly.

1) Quality rating scale of each parameter is calculated ^[34] by using following formula quality rating scale

Where Vo= observed value or mean of the observed values of any parameter.

Vi= ideal value of that particular parameter

Vi= 0 for all parameters except p^H & DO

Vi for p^H= 7 & Vi for DO= 14.6 mg/l.

Vs= Standard permissible value of particular parameter, determined by WHO.

2) Calculation of relative unit weight (Wi)- The relative unit weight of any parameter (Wi) α 1/Si or Wi= K/Si

Where Si= standard permissible value of particular parameter

K= proportionality constant.

For the sake of simplicity K is taken as 1.

3) Finally water quality index=

The overall quality of any water body is assessed by using following WQI level given below:-

In other words

i. 0<WQI < 100 fit for human use

ii. 0> WQI>100 unfit for human use ^[15].

Water Quality Index (WQI) of monitoring station Hadagada has been given in Table 8 as for example & WQI for other eight monitoring stations have been calculated in a similar way & presented in Table 9 for study and to derive conclusion.

Table 9. Water Quality of river Salandi for nine monitoring Stations

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3. Result & Discussion

WQI

The water quality index of present water body under study has been assessed by taking twelve important parameters into consideration & has been presented in Table 9. The value calculated are 43.1737, 98.3067, 108.7467, 147.0829,108.0049,55.4871,44.3559,39.2897 & 83.88718 for monitoring stations Hadagada, Bidyadharpur, Agarpada, Randia, Baudpur, Rajghat, Satabhauni, Dhusuri & Akhandalmani respectively. It indicates that different stations have different WQI values & hence different water quality ^{[5, 19, 26, 30, 37]}. Further WQI calculated for different monitoring stations has been supported by the interpretation of following physico- chemical parameters along with graphs given & it highlights that no station comes under class A quality. Besides, the monitoring stations at Hadagada, Satabhauni & Dhusuri come under class B, Rajghat comes under class C, Bidyadharpur, Baudpur & Akhandalmani are very poor and unfit for drinking purposes.

p^H

The p^H of water sample of nine monitoring stations was measured form the month of April to December in 2015. It was observed that although there is slight variation, but it is within the prescribed standard limit IS-10500 ^[25] (6.5 – 8.5). Further higher p^H is observed from the month of April to December except May in the monitoring stations from Hadagada to Dhusuri. The comparatively low p^H in the month of May can be attributed due to low flow of water which raises the concentrations of acidic pollutant ^{[1, 3]}. The higher p^H may be due to photosynthesis by aquatic plants as in the process of photosynthesis the aquatic plants ^{[3, 17, 18]} consume dissolved carbon dioxide and hence increases p^H. Besides, high water content of the river dilutes the pollutants ^[36]. But at the monitoring station Akhandalmani the pH changes from 6.9 (in May) to 7.3 (in other months). The lower p^H in the month of May can be due to unseasonal rainfall runoff in the coastal region as because Akhandalmani is nearer to Bay of Bengal.The mean value of pH from the month of April to December, 2015 for nine different stations is given in Figure 1. From the mean value, it is evident that pH is lowest in Hadagada (6.96) and increases gradually up to Baudpur and then decreases and reaches minimum at Rajghat (6.9) and again increases to maximum at Akhandalmani (7.2). The lowest pH at Hadagada is due to receiving of forest runoff, mining runoff and lowest pH at Rajghat may be due to the receiving of medical wastes as district head quarter hospital and private hospitals are closer to it.

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Figure 1. P^Hfor nine different sampling stations, 2015

TDS & Turbidity

The variation of TDS & turbidity is nearly equal. But from the month of August to October, both TDS & Turbidity are higher due to high rain fall run off, forest run off, mining run off, agriculture run off along with entering of domestic wastes to the river water in large scale ^{[19, 20]}. The higher TDS value in the monitoring station at Akhandalmani from the month of April to October is due to the back flow of sea water ^[35] as because the station is nearer to sea shore. The mean TDS value from April to December, 2015 for nine different stations is given in Figure 2.

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Figure 2. TH & TDS for nine different sampling stations, 2015

TH, Ca, Mg, NO_3, SO_4,PO₄& Cl

All the values for above parameters except TH, Ca & PO₄are within the prescribed limit for drinking water IS-10500, in rainy (August) and post rainy (October) though there is variation in quantity. But the monitoring station at Akhandalmani, the results are high in all times of monitoring as back flow of sea water takes place from the sea (Bay of Bengal). But it is worth mentioning that the results are higher in rainy (August) & post rainy (October) than summer & winter. Further it is marked that mean values of TH increase from Hadagada (87.2) to Dhusuri (92.2) in an irregular way & between the months of April & May, TH is higher in May than April due to low flow of water that raises the concentrations. The higher values of all parameters in rainy & post rainy than summer and winter is due to entering of mining effluents, Industrial effluents, urban waste and agricultural effluents along with forest run off and anthropogenic activities such as septic tank effluents, animal feeds and use of bleaching reagents by launderers. The agricultural effluents contribute significantly as pesticides and certain fertilizers such as Calcium Ammonium Nitrate (CAN), basic calcium nitrate, calcium superphosphate used by the farmers for cultivation purpose release sulphates, nitrates, calcium, phosphates and heavy metals to surface water bodies ^{[6, 14, 21, 31, 36]}. In ideal condition plants use only 50% of nitrogenous fertilizers applied, 2-20% lost due to evaporation 15-25% reacts with organic compound of soil & remaining 2-10% interfere with surface & ground water ^[21]. The mean value of TH from April to December, 2015 for nine different stations is given in Figure 2 & mean values of SO₄ and NO₃ for the above nine stations are given in Figure 3.

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Figure 3. SO4^2- & NO₃^-for nine different sampling stations, 2015

Fe (>0.3) & Cr (>0.05)

Iron & hexavalent Chromium are found to exceed permissible level or touching the permissible level in the monitoring stations during summer, rainy, post rainy & winter season. This is mainly due to the receiving of mining effluents from Nuasahi Chromite belt, Industrial sector at Randia (FACOR), urban effluents of Bhadrak Municipality and agricultural effluents. The high concentration of Iron (> 0.3) at Bidyadharapur in the month of August (0.59) and October (0.58) is due to the mixing of the mining effluents in the river water and particularly in the month of December, it is much more in all monitoring stations (0.59 at Hadagada to 4.9 at Akhandalmani) in comparison to other months. It may be due to interaction of soil containing iron ore with water that promotes the mixing of iron with river water, happened at the lower part of the river as because water level is very low due to low flow of water ^[6].

As regards hexavalent chromium, its permissible value is 0.05ppm (IS-10500), but at the monitoring station Randia, the river water contains more than the permissible level. It is due to discharge of chromium effluents from ferro-chrome plant at Randia ^{[28, 29]}. Further it is observed that Hexavalent chromium is more in the month of August and October. It may be due to the excessive use of some chemical fertilizers and pesticides that contains heavy metals chromium ^{[7, 9, 14, 21, 36]}. Presently some chromite mines are not running due to lack of environmental clearances as well as forest clearances. But earlier report of pollution control board revealed that they have discharged the effluents of high concentration of chromium to the river Salandi. Although presently some chromite mines are not running, but mining wastes left by them earlier without proper treatment has resulted open exposure of chromite mixed soil to the atmosphere and pollutes the river Salandi with chromium through atmospheric rain water precipitations as the river Salandi is the only natural drainage system in the study area. Hence more concentration of hexavalent chromium in the month of August and October is found in the monitoring stations from Bidyadharapur to Baudpur is due to the entering of mining run off, industrial runoff, agricultural runoff ^{[8, 10]} & atmospheric precipitations ^{[11, 12, 13]} to the river Salandi. The mean value of Fe & hexavalent Cr from April to December, 2015 for nine different monitoring stations are given in Figure 4. From the mean values of iron it is evident that the concentration of iron increases from Hadagada to Bidyadharpur and decreases gradually and reaches maximum at Akhandalmani (1.35). It is due to entry of mining effluents to the river and it is diluted from upstream to downstream. The highest value of iron at Akhandalmani may be due to the back flow of sea water that might contain higher amount of iron ^[36].

3.1. Dissolved Oxygen (DO)

The dissolved oxygen is a crucial parameter for river water system which supports the survival of aquatic creatures & its value less than 6 mg/L (minimum requirement) will endanger the life of aquatic creatures ^[25]. But due to indiscriminant discharge of industrial, urban, mining, agricultural & domestic wastes to the river system, the dissolved oxygen value is decreased as it is used in redox reaction process to stabilize the pollutant in water bodies. Further anthropogenic activities such as washing of clothes, open defecation & picnic in river bed add fuel to the fire ^{[19, 21]}.

In the present study, it is seen from the monitoring values of river Salandi that dissolved oxygen values are constantly influenced from upstream to downstream by the aforesaid factors. The mean values of dissolved oxygen decreases gradually from Hadagada (7.12) to Akhandalmani (7.02) through mid stream with lowest at Rajghat (6.5). Further it is observed that lower value of dissolved oxygen from 6.7 to 6.8 in the mining belt & 6.2 to 6.6 mg/L at Rajghat during summer (April & May) may be due to eutrophication & mixing of mining & urban contaminants to the river water. The higher values of dissolved oxygen in rainy (August) & post rainy (October) is due to high flow of rain water, flood & aeration that dilute the organic pollutants in the river ^{[1, 35]}. The mean DO value from April to December, 2015 for nine different stations is given in Figure 5.

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