Department of Environmental Science, The University of Burdwan, Golapbag 713 104, West Bengal, India
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The present research work deals with the characterization of industrial effluents released from various industries and the impact of Damodar river water quality with respect to major chemical constituents along with heavy metals. Damodar river water is being extensively harnessed from both of its banks for domestic, industrial and irrigation purposes. Various anthropogenic activities like mining, ultimate disposal of untreated waste effluents containing toxic metals from different industries resulted in deterioration of water quality rendering serious environmental problems. The objective of the study is to understand the elemental composition of the river water, the influence of anthropogenic activities on riverine chemistry and the transport of metals from effluent channels to the river. Various physico-chemical parameters were determined following the standard methods of APHA (1998). The obtained data were subject to statistical analysis to study the correlation and factor analysis among all the parameters. The level of Cd in the effluent channel or in the river samples was within the range of the tolerance limits for industrial effluent discharged to inland surface waters according to Indian standards (IS 2490 Part I: 1981) and WHO drinking water standards (2006). Pb concentration in the tamla nala is extremely high with a mean of 0.535 mg/L which is far greater than the IS discharge limits of inland surface waters. The Pb concentration at the discharge point of IISCO and tamla nala exceed the drinking water standards. The substantial difference in the parameters analysed for effluent and river water revealed a significant degradation of the water quality at effluent discharge point.
Industrial effluents, Characterization, Heavy metal pollution, Factor analysis, Damodar river
Rapid urbanization and industrialization have resulted in increased waste loads which are discharged into rivers without any prior treatment. River water contamination due to wastewater discharge is a major environmental concern. Surface water quality is affected by both the anthropogenic activities and natural processes (Mokaya et al. 2004; Melina et al. 2005; Singh et al. 2005a). Therefore, monitoring of heavymetals is important for safety assessment of the environment in general and human health in particular. The present river water quality study is an attempt to detect the changes in the water quality characteristics due to the discharge of wastewater in Damodar river with respect to major chemical constituents along with heavy metals. Cadmium and lead along with some physicochemical parameters were assessed in water in four areas along the river Damodar in West Bengal, India. Damodar river water is used to an increasing extent as drinking and irrigation water in urbanized, industrialized as well as agricultural areas.
River Damodar in Durgapur–Asansol industrial region receives waste waters from various industries like steel plant, coke oven and coal based chemical industries besides distilleries and paper mills (Chakraborti, 1994). In addition to water pollution by nutrients or organic compounds, the heavy metal content in flowing waters has become one of the most important problems because of its toxic effect even in minor concentrations. Heavy metals are either naturally or through anthropogenic sources are introduced into the river water. Metals that are naturally introduced into river come primarily from sources such as rock weathering, soil erosion, and the dissolution of water-soluble salts. Anthropogenic pollutants discharged from activities like industrial, domestic and agricultural wastewater into the river water system (Ho and Hui, 2001 & Priju and Narayana, 2007). Pollutants in industrial wastewater are almost invariably so toxic that wastewater has to be treated before its reuse or disposal in the water bodies.
The mining and its related operations are the most significant anthropogenic sources of heavy metals that negatively influence the nearby environment (Conesa et al. 2007; Vanderlinden et al. 2006; Vanek et al. 2005). Widespread use of heavy metals in industries as well as intensive agriculture has resulted in a variety of heavy metals being released into the environment with concentrations in excess of the natural background levels (De Groot et al. 1976; Dryssen and Wedborg, 1980). Human activities are able to influence the aquatic chemical composition, mainly sodium, chloride, sulfate and nitrate (Bluth and Kump, 1994).
In living systems essential metals like iron, nickel, zinc, vanadium, manganese, molybdenum, cobalt, chromium, tin, and copper are required in micro amounts although at higher concentrations the metal ions are toxic. Non essential metals like cadmium, mercury, lead, titanium, arsenic, antimony, and bismuth are not required by living systems. Cadmium is the best known toxic metal and it is used in electroplating, battery, paints and plastic industry (Tyagi and Mehra, 1992). According to Bowen (1966) the lead is not essential as a trace metal to nutrition in animals, but is a cumulative poison. Lead is used in piping, building materials, paint, ammunition, castings, storage batteries, metal products, chemicals and pigments. Effects of lead include anaemia, severe abdominal pain, diarrhoea, sleep disorders, neurobehavioral effects, cardiotoxicity, impairment of the thyroid and adrenal functions. The objective of the study is to characterize the effluents discharging into the riverine system and to determine the river water quality using a number of parameters and to compare it with Water Quality Guidelines.
Description of the study area
Damodar is a rain fed river, originates near Chandwa village, Palamau district, on the Chota Nagpur Plateau in the Jharkhand state in eastern India, and flows through the cities Ramgarh, Bokaro, Dhanbad, Asansol, Durgapur, Bardwan and Hawrah, before ultimately joining the lower Ganga (Hooghly estuary) at Shayampur, 55 km downstream of Hawrah. The study area experiences typical monsoon climate with extreme summer followed by the rainy season. Lead and Cadmium along with some physicochemical parameters were assessed in three seasons (summer, rainy season and winter of 2007) in effluent discharge channel and river water in four sampling stations (SS I-IV) – Sampling station I: designated as IISCO (Indian Iron & Steel Co. Ltd.) discharge point, Sampling station II: designated as Nunia discharge point (carrying municipal as well as industrial wastewater), Sampling station III: designated as Tamla discharge point (a natural storm water channel also carrying industrial wastewater), Sampling station IV: designated as Dhobighat discharge point (storm water channel). The material used and methods followed during the course of studies are mentioned below.
Samples and sampling
The samples were collected in 1lit high-density polyethylene bottles prewashed with nitric acid and rinsed three to four times with the water sample before filling them to the required capacity. Effluent samples were collected from effluent channel and the river water samples collected from the discharge point of receiving river. The unfiltered effluent and river water samples for total metal analysis were preserved using ultra pure nitric acid to lower the pH to <2.0. The samples thus preserved and brought to the laboratory for heavy metal analysis. The collected samples were stored in ice box for further analysis after determining pH and electrical conductivity. EC and pH of water samples were measured in the field immediately after the collection of the samples using pH and conductivity meters
Samples were filtered and stored in plastic bottles and analysed for major cations (NH4+ Na+, K+, Ca2+) and major anions (SO42-, Cl-, NO3-, F-) following standard analytical methods (APHA, 1998). The lead and cadmium were analysed using a atomic absorption spectrometer (GVC Avanta). SO42-, NO3-, Fe, NH4+, analyzed using UV-visible spectrophotometer. Ca2+ was determined titrimetrically using standard EDTA. Chloride was estimated by AgNO3 titration. All the results are compared with standard limits recommended by Indian standards (IS 2490 Part I: 1981) and World Health Organization (WHO, 2006).
The concentrations of lead (Pb) and cadmium (Cd) along with some physico-chemical parameters were represented in Tables 1.1 and 1.2. Pearson’s correlation (r) matrix of different effluent and water quality parameters is represented in Table 2.
The higher value of mean concentration (0.535 mg L–1) of lead was observed in the effluent of tamla nala and it ranges from (0.528-0.545 mg L–1) with standard deviation and standard error value 0.009 and 0.005 respectively (Table 1.1) (Fig. 1.1). The higher value of mean concentration (0.237 mg L–1) of lead was observed in discharge point at Majhermana (tamla discharge point) and it ranges from (0.228- 0.246 mg L–1) with standard deviation and standard error value 0.007 and 0.004 respectively (Table 1.2). Tamla nala contains effluents from metal processing and chemical industries where large amounts of the heavymetals are used as raw materials or as process catalysts. At the site III effluent channel the values of lead exceeds the IS discharge norms (0.1 mg L–1) for effluents into surface water bodies (IS 2490 Part I: 1981). At the site III discharge point the values of lead exceeds the WHO norms (0.01 mg L–1) for drinking water (WHO, 2006).
The higher value of mean concentration (0.620 μgL–1) of cadmium was observed in the effluent of tamla nala and it ranges from (0.540-0.690 μgL–1) with standard deviation and standard error value 0.8 and 0.4 respectively (Table 1.1) (Fig. 1.2). The higher value of mean concentration (0.560 μg L–1) of cadmium was observed in discharge point at Majhermana and it ranges from (0.530-0.600 μg L–1) with standard deviation and standard error value 0.004 and 0.002 respectively (Table 1.2). Concentrations of Cd showed little fluctuations in the river water, ranging from 0.00 to 0. 0.60 μg L–1. The concentration of Cd was found to be well below the IS discharge norms (2 mg L–1) for effluents into surface water bodies (IS 2490 Part I: 1981) and WHO norms (0.003 mg L–1) for drinking water (WHO 2006) for all the samples.
Heavy metals are widespread pollutants of great environmental concern as they are nondegradable, toxic and persistent in nature(Chopra et al., 2009, Jumbe et al., 2009) and have toxic effects on living organisms, when they exceed the certain concentration (MacFarlane et al., 2000; Dalman et al., 2006; Chen et al., 2007). The cadmium and lead represent a coherent group of metals both from the metallogenic point of view, and as contaminants of the environment (Thornton and Webb, 1981; Peterson and Alloway, 1979; Davies, 1981). Lead is a toxic heavy metal accumulate in aquatic biomass, they are concentrated and passed up the food chain to human consumers. Cadmium is of even greater concern because of its harmful effects on plants, animal and man also. However, heavy metal concentrations in surface water which are not very high, dilute and undetectable quantities, their recalcitrance and consequent persistence in water bodies exhibiting toxic characteristics (Atkinson et al. 1998).
The samples of effluent channel exhibited an alkaline pH in the range of 7.83 to 8.46 with an overall mean of 8.06. The samples of discharge point exhibited an alkaline pH in the range of 7.87 to 8.57 with an overall mean of 8.13. pH of the effluent channel found within the prescribed limit set by the BIS. pH level of a water system determines its usefulness for a variety of purposes. The high Electrical conductivity indicates a larger quantity of dissolved mineral salts (Trivedy and Goel, 1986) and making it unsuitable for drinking (Srivastava et al. 1996). The samples of effluent channel exhibited electrical conductivity in the range of 326.66 μS/cm to 626.66 μS/cm with an overall mean of 498.33 μS/cm (Fig. 1.4). The samples of discharge point exhibited electrical conductivity in the range of 313.33 μS/cm to 523.33 μS/cm with an overall mean of 435.83 μS/cm. The hydro-chemical sources and natural factors strongly influence the water quality of the study area. The result generally showed a negative impact of the discharged effluent on the receiving river and suggest for a regular and consistent monitoring program.
Na+(r = 0.448) and K+ (r = 0.296) (Table 2). Heavymetals were positively correlated with each other, Pb bears positive correlation with Cd (r= 0.569), Fe (r= 0.394).
Factor analysis (PCA extraction)
Factor analysis (FA) was applied to study the water quality status of river Damodar. Eigenvalue gives a measure of the significance of the factor and the factors with the highest eigenvalues are the most significant. According to Liu et al. (2003) factor loading is classified as ‘strong’, ‘moderate’ and ‘weak’, corresponding to absolute loading values of > 0.75, 0.75-0.50 and 0.50-0.30, respectively. Component loadings of principal components for each season are presented in Fig. 2. Factor 1 which was moderate positively loaded with Pb, Cd, E.C. NH4 (week), SO4, K, Cl and Fe (Table 3), seemed to be related to urban and industrial sources, both of which are the results of anthropogenic activities. The strong positively loaded was NO3 and F and the strong negatively loaded was pH in factor 2 which represented the mineral-related hydrochemistry of the surface water. Factor 3 which is relatively small comparison with other factors the Na (strong positively loaded) and Ca (week negatively loaded) were found, which may be due to natural sources. These parameters were determined that industrial discharge, geogenic sources and natural factors strongly influences the water quality of the study area.
The major factor which decides the quality of the river water in the study area is industrial activities near the stretch of the river at the confluence point of wastewater discharge channels. The study reveals that there is a considerable variation in the concentration of heavy metals in effluent channel and river water. Iron is found in significant amounts in the site I discharge point as it contains effluents from IISCO (Indian Iron and Steel Company). The highest metal concentrations were detected at effluents of tamla nala due to the discharge of heavy metal loaded industrial waste water and this allowed identifying some sources of pollution in the river. From the factor analysis it was observed that the industrial discharges, geogenic sources and natural factors strongly influence the water quality of the study area. The result generally showed a negative impact of the discharged effluent on the receiving river and suggest for a regular and consistent monitoring program.
The authors wish to thank Prof. J.K. Datta, Prof A.R. Ghosh and Dr N.K. Mondal, Dept of Environmental Science, The University of Burdwan, West Bengal for their valuable suggestions and cooperation throughout this research work.