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Heavy metals in the midstream of theGanges River: spatio-temporal trends ina seasonally dry tropical region (India)Anand V. Singha & Jitendra Pandeya

a Laboratory of Trans-Boundary Research on Ganges Basin andClimate Change Drivers, Environmental Science Division, Centreof Advanced Study in Botany, Banaras Hindu University, Varanasi,IndiaPublished online: 02 Jun 2014.

To cite this article: Anand V. Singh & Jitendra Pandey (2014): Heavy metals in the midstreamof the Ganges River: spatio-temporal trends in a seasonally dry tropical region (India), WaterInternational, DOI: 10.1080/02508060.2014.921851

To link to this article: http://dx.doi.org/10.1080/02508060.2014.921851

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Heavy metals in the midstream of the Ganges River: spatio-temporaltrends in a seasonally dry tropical region (India)

Anand V. Singh and Jitendra Pandey*

Laboratory of Trans-Boundary Research on Ganges Basin and Climate Change Drivers,Environmental Science Division, Centre of Advanced Study in Botany, Banaras Hindu University,Varanasi, India

(Received 16 August 2013; accepted 4 May 2014)

Midstream concentrations of Cd, Cr, Cu, Fe, Ni, Pb, Mn and Zn were studied at eightsampling sites in the Ganges River at Varanasi from March 2011 to February 2013.Concentrations were lowest at Site 1 (upstream of the urban core), increased consis-tently downstream, and were highest at Site 8 (downstream of the urban core). Therank of concentration was Zn > Fe > Pb > Mn > Cu > Ni > Cr > Cd. Except for Zn,concentrations were highest in winter. Cr, Cu, Ni, Mn and Zn did not exceed theirinternationally recommended maximum admissible concentration (MAC). However,over 80% of the water samples contained Cd, over 70% Pb and about 50% Fe abovetheir respective MACs of 3.0, 10.0 and 300 µg L−1. Since the river water is used forirrigation and drinking purposes, the study has relevance from a human healthperspective.

Keywords: environmental assessment; river basin management; water quality; waterresources

Introduction

The Ganges River is one of the most utilized rivers in the world. Being a perennial-glacialriver, it has played an important role in the development of Indian civilization andeconomy. Increased urbanization and industrialization in the basin, however, have causedlarge-scale degradation of water quality of the river along its 2525 km course fromGangotri in the Himalayas to the Bay of Bengal (Pandey, Pandey, & Singh, 2014).Over its long course, the river receives a wide array of chemical constituents, includingtoxicants from a variety of natural and anthropogenic sources (Kar, Sur, Mandai, Saha, &Kole, 2008). Heavy metals, unlike organic pollutants, are not removed by natural pro-cesses of decomposition. A significant fraction of the pollutants that enter the river may betransported to the Bay of Bengal. The pollution of aquatic ecosystems by heavy metalshas assumed serious concern due to their toxicity and accumulative behaviour. Thesepollutants are introduced into aquatic systems through natural processes such as weath-ering and volcanic eruptions and from a variety of human activities. Metals entering intothe natural waters become part of the water–sediment system, and their distributionprocesses are controlled by a dynamic set of physical and chemical equilibria. Heavymetals in sediments of the Ganges River were studied by Purushothaman and Chakrapani(2007) and Beg and Ali (2008). Metal partitioning between water and sediments isprincipally controlled by pH, forms of the metal, concentration and types of ligands and

*Corresponding author. Email: jiten_pandey@rediffmail.com

Water International, 2014http://dx.doi.org/10.1080/02508060.2014.921851

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chelating agents, oxidation state of mineral components and the redox environment of theaquatic system. The distributions of heavy metals in water and sediments vary from riverto river and play a key role in identifying the sources of their input in aquatic ecosystemsas well as their bioavailability and toxicity (Beg & Ali, 2008; Pandey, Pandey, &Shubhashish, 2009).

Rising levels of toxic metals in air, soil and water is a global problem and a growingthreat to humanity. In addition to direct toxicity, heavy metal contamination of water maychange the physicochemical composition of water, and as a result the water may becomeunsuitable for human consumption. Heavy metals are known to cause serious healthproblems, including carcinogenesis – induced tumour promotion (Schwartz, 1994). Thegrowing consciousness of the health risks associated with heavy metals has brought amajor shift in global concern towards prevention of heavy-metal accumulation in soil,water and edible materials. Toxic metals have been shown to significantly contaminatesoil and vegetables, causing a serious risk to human health when such plant-based food-stuffs are consumed (Pandey & Pandey, 2009a, 2009b; Voutsa, Grimanis, & Samara,1996). Intake of such elements also depends on irrigation and drinking-water use. Theremay not always be a strong relation between the concentrations of such elements in soiland plants (Siegel, 2002), but there always exists a strong relation between metalconcentrations in irrigation water and plants (Ahmad & Goni 2010; Pandey,Shubhashish, & Pandey, 2012). Additionally, intake of heavy metals through drinkingwater can further enhance their accumulation in the human body. This merits seriousconcern because Ganges River water is used for both irrigation and drinking-water supplyfor a large population.

There are hundreds of sources which add heavy metals to the environment. Theseinclude vehicular emissions, waste incineration, coal mining, natural gas, paper indus-tries, petrochemical industries, metallurgy, ceramic industries, refineries, steel industry,chlor-alkali and other industries (Alloway, 1995). Rapid development of the urban andindustrial sectors is therefore believed to be the major cause of heavy-metal pollution inwater, soil and air, contaminating a wide range of ecosystems. All these sources addmetals to surface waters, mainly through surface discharge. Earlier studies have indi-cated urban sewage and industrial effluents to be the main factors responsible fordeteriorating Ganges River water quality (Jain, 2002; Singh & Singh, 2007). Recentstudies conducted in our laboratory indicate long-distance atmospheric transport anddeposition of heavy metals, contaminating terrestrial as well aquatic environments,including the Ganges River (Pandey & Pandey, 2009a, 2009b; Pandey et al., 2009,2010). Most of the surface discharge sources contaminate soil and water bodies in aspatial range, but aerial emissions allow long-range transport, contaminating a widerrange of ecosystems, especially those downwind of the emission source (Pandey et al.,2009). More importantly, unlike surface discharge, where streamflow restricts mid-stream contamination, atmospheric deposition directly adds heavy metals to the mid-stream. The data available so far on heavy metal contamination of the Ganges River arebased on bankside water sampling (Singh & Singh, 2007) and sediment analysis (Beg &Ali, 2008). Data on midstream heavy-metal contamination of the Ganges River are veryscarce. The present study quantifies the magnitude and intra-annual variation in heavy-metal contamination in midstream water of the Ganges River. The purpose was also tosee whether there is a significant difference between stations situated upstream anddownstream of the urban core.

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Materials and methods

Study area

The present study was conducted between March 2011 and February 2013 along a 35 kmstretch of the Ganges River at Varanasi (25°18′ N, 83°1′ E), in the midst of the easternGangetic plain at 76.19 m above mean sea level (Figure 1). The river shows markedseasonality in water discharge: highest in the rainy season (13,470 m3/sec), lower inwinter (1512 m3/sec), and lowest in summer (445 m3/sec). The climate of the region istropical with distinct seasonality. The year can be divided into a hot and dry summer(March to June), a humid rainy season (July to October), and a cold winter season(November to February). During the study period, mean annual rainfall varied between870 and 1100 mm, and relative humidity between 27% and 83% (summer) or 58% and99% (rainy season). During summer, daytime temperature varied between 29 °C and 46 °C. During winter, the temperature sometimes drops below freezing overnight. The winddirection shifts from predominantly westerly and south- westerly in October through Aprilto easterly and north-westerly in the remaining months. The soil of the region is alluvialand predominantly sandy loam.

Eight sampling stations were selected along a 35 km stretch of the river, and three sub-sites were selected at each station. Site selection was based on catchment heterogeneityand the magnitude of anthropogenic influences. Site 1 is located in a relatively naturalenvironment, while all the others are in areas affected by human activities (Table 1).Samples were collected during two consecutive years: March 2011 through February 2012

Figure 1. Location map showing study sites on the River Ganges.

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(designated hereafter as Year 2011) and March 2012 through February 2013 (designatedhereafter as Year 2012).

Sample collection and analysis

Water samples were collected from each site in pre-sterilized polythene bottles, directlybelow the surface (15–25 cm depth), at fortnightly intervals during the study period. Thedistance between replicate samplings (n = 3) was about 50 m. All water samples werebrought to the laboratory and preserved with HNO3. Water samples (50 ml) were digestedwith 10 ml of concentrated HNO3 at 80 °C for the analysis of heavy metals (AmericanPublic Health Association [APHA], 1998). The solution was filtered through WhatmanNo. 42 filter paper and diluted to 50 ml with double-distilled water. The concentrations ofheavy metals (Cd, Cr, Cu, Fe, Ni, Mn, Pb and Zn) in the filtrate were determined using anatomic absorption spectrophotometer (Perkins-Elmer AAnalyst 800), fitted with a specificlamp of particular metal using the appropriate drift blank. The detection limits (µg/L−1) ofheavy metals were 0.0005 (Cd), 0.002 (Cr), 0.001 (Cu), 0.005 (Fe), 0.004 (Ni), 0.002(Mn), 0.01 (Pb) and 0.001 (Zn). The chemicals used were Merck analytical grade.Quality-control measures were taken to assess contamination and reliability of data.Blank and drift standards (Sisco Research Laboratory, India) were run after five readingsto calibrate the instrument.

Statistical analysis

The standard error (SE) of mean and coefficient of variation were computed to expressdeviation and range of variability. Significance levels of spatio-temporal variation weretested using analysis of variance (ANOVA). Samples were collected in replicates, and allthe measurements, except a few that were excluded for not following a normal distributionpattern, were considered in the ANOVA model. Confidence limits above 95 (α < .05)

Table 1. Description of sampling sites.

No. Name Code Description

1. Adalpura Adpr Upstream of Seetlamata Temple; relatively undisturbed;receives predominantly natural runoff

2. Bypass upstream Byus Upstream of bypass highway; emission from heavyvehicles, rural and agricultural runoff, industrialemissions*

3. Bypass downstream Byds Downstream of bypass highway; emission from heavyvehicles; dredging influences runoff

4. Samne Ghat Smht Near pontoon bridge; runoff from residential land uses5. Assi Ghat Asht Urban core; runoff from residential land uses, urban

surfaces6. Dashaswamedh Ghat Dsht Near historical Dashaswmedh Ghat; urban core; urban-

surface runoff7. Rajghat upstream Rjus Upstream of Malviya Bridge; urban core; biomass burning

and urban surface runoff8. Rajghat downstream Rjds Downstream of Malviya bridge; post-urban; runoff from

woodland; downstream influence of Varuna River#

* Including iron industries, paint factory, cement factory, and paper and board mills.# A small tributary of the Ganges River, contaminated with sewage water.

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were considered significant. SPSS (version 16) was used for these analyses. The Mann-Kendal test and Sen’s slope estimator were used to detect trend direction and magnitude ofintra-annual changes (XLSTAT 2013). A principal components analysis (PCA) ordinationwas conducted using PAST software to mark the distribution of sample locations andheavy metals on the study gradient. Box-and-whisker diagrams were used to present theoverall range of metal distribution in the study stretch of the Ganges River.

Results

Metal concentrations in midstream river water increased consistently along the studygradient from Site 1 (Adalpura) to Site 8 (Rajghat downstream) (Figure 2). Seasonally,recorded metal concentrations in the water were highest in winter, followed by summer,and lowest in the rainy season (Figure 3). This pattern of seasonality was displayedconsistently for all the heavy metals except Zn, of which the concentrations were highestin summer, followed by winter, and lowest in the rainy season (Figure 3). Further, theconcentrations were higher in Study Year 2. These spatio-temporal trends were commonto all the heavy metals considered in this study (Figure 4). Between-site differences inmetal levels were statistically significant (ANOVA, Table 2). Within-site varianceappeared site-specific and did not show a particular trend. In general, the largest within-site variability was observed at Site 8, where the coefficient of variation ranged from 17%to 26%. ANOVA indicated significant interannual differences for all heavy metals,although seasonal differences were less marked. Despite heterogeneous distribution,PCA ordination revealed two axes (the first two principal components) that explainmost of the variation in metal concentration (Figure 5). With respect to metals, PCAidentified Zn and Fe on one side and the remaining heavy metals in the direction oppositeto Zn and Fe. Metals such as Cu, Cd, Cr, Ni, Pb and Mn were all clustered separately,almost in the centre of PC 2 (Figure 5). The box-and-whisker plot displays Zn and Fe asthe dominant heavy metals in the river across the study stretch (Figure 6). Although bothmetals showed wider ranges of distribution, the inter-quartile range was greater for Fethan for Zn and other metals (Figure 6).

The concentrations of Ni (detection limit to 19.76), Cr (detection limit to 15.27 µg L−1),Mn(2.61–34.76 µg L−1), Cu (2.43–26.76 µg L−1) and Zn (250.12–290.25 µg L−1) in midstreamwater at all eight locations were well below their internationally recommended (WHO)maximum admissible concentrations (MACs) of 20, 50, 100, 1000 and 5000 µg L−1,respectively (WHO, 1996). However, the concentrations of Cd and Pb at seven locationsandof Fe at four locationswere higher than their respectiveMACsof 3.0, 10 and300µgL−1.

Discussion

In addition to the natural input of chemical constituents, the solute chemistry of surfacewaters depends on a combination of anthropogenic controls, such as hydrological pointdischarge (including sewage outlets), nonpoint discharge (including urban and agriculturerunoff), and atmospheric deposition. The present study provides evidence of a combinedinfluence of atmosphere-land-water transfer regulating heavy-metal concentration in theGanges River. There were significant between-site differences in the concentrations of thestudy metals. Interannual differences were also significant for all the heavy metals.Seasonally, except for Zn, metal concentrations in water were highest in winter, followedby summer, and lowest in the rainy season. In general, the metal concentrations observed inthis study are comparable to those observed at Lower Cross River basin in south-eastern

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Nigeria (Edet & Offiong, 2002) and, in a few cases, to the Sabaki and Ramisi Rivers, whichflow into the Indian Ocean from Kenya (Ochieng, Lalah, & Wandiga, 2009).

The study presents data on three interlinked but well-defined contexts: seasonalvariations to explain within-year influence of rainfall/river discharge; interannual varia-tions to explain rising trends over time; and site-wise variations to explain the influence ofurban core and other sources. Mann-Kendall trend analysis and Sen’s slope estimatesshow statistically significant seasonality, with increasing trends in metal concentrationalong the gradient. This could be explained in a major way by changing rainfall/riverdischarge. Urban stormwater is well established to influence the quality of receiving

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Figure 2. Mann-Kendall trend analysis with Sen’s slope statistics for eight heavy metals in theGanges River at different study sites. S′ = Sen’s estimate; SS = Sen’s slop.

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waters (Jeng, Englande, Bakeer, & Bradford, 2005) and is a major contributor of heavy-metal pollution (Buffleben, Zayeed, Kimbrough, Stenstrom, & Suffet, 2002; Kar et al.,2008; Lee, Lau, Kayhanian, & Stenstrom, 2004). Further, although the first-flush phe-nomenon may enhance pollutant concentrations initially (Lee et al., 2004), the massiverise in water discharge of the Ganges River from 445 m3/sec in summer to 13,470 m3/sec

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Figure 3. Spatial and interannual variation in the concentration of heavy metals in midstream waterof the River Ganges at Varanasi. Values are mean (n = 24) ± 1 SE. Horizontal lines representmaximum admissible concentrations established by WHO. #Values below detectable limits.

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in the rainy season could substantially dilute metal concentrations in the rainy season.Previous studies have shown that high amounts of metals entering the river through land-based runoff during the rainy season may be transported into the sea (Balkis, Aksu, Okuş,& Apak, 2010). This has relevance for the Ganges River, which receives massive runofffrom its 2525 km catchment characterized by diverse human activities which invariablycause environmental release of heavy metals.

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Figure 4. Intra-annual variation in the concentration of heavy metals in midstream water of theRiver Ganges at Varanasi. Values are mean (n = 30) ± 1 SE. Horizontal lines represent maximumadmissible concentrations established by WHO. #Values below detectable limits.

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Figure 5. Principal components analysis ordination showing distribution of (a) sampling sites and(b) heavy metals along the first two principal components. Sample locations/metals distributed in thesame direction and close sectors indicate the common controlling factors, while those distributed inopposite directions of the ordinate show poor linkages and influence of other factors.

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Figure 6. Box-and-whisker plot showing distribution of eight heavy metals in the Ganges River atVaranasi. Except for Cd, the lower whiskers are longer than the upper ones.

Table 2. F-ratios obtained from analysis of variance indicating significant effectsof site and year on eight heavy metals measured in the Ganges River at Varanasi.

Variable Site Year Site × year

Cd 516.51** 14.12** 0.85Cu 1076.00** 39.13** 1.43Cr 1770.00** 52.29** 0.65Fe 1676.00** 41.74** 1.82Mn 1814.00** 77.88** 4.32**Ni 1259.00** 39.76** 0.47Pb 2063.00** 30.91** 3.25*Zn 711.072** 13.12** 4.31**

*p < .05. **p < .01.

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The consistently increasing trend in heavy-metal concentrations down the river indi-cates a strong influence of local controls, including the contribution of Varuna streaminflow at Site 8. The upstream influences contribute significantly to overall water chem-istry and may be considered ‘background’ concentration while assessing the local controls(a combination of hydrological point discharge including sewage outlets, non-pointdischarge including urban stormwater runoff, tributary inflow, and atmospheric deposi-tion). Metal concentrations in river water may remain high in the vicinity of sourcesbecause the reactions taking place at the surface of freshly added sediments act to enhancethe sinking of metals to bottom sediments (Purushothaman & Chakrapani, 2007). Humanactivities continuously add heavy metals to receiving waters, directly or through catch-ment runoff. In the present study, except for Site 1, all the study locations are affected byhuman activities. It has been established that suspended particulate matter and runoff aresignificant transport agents for trace metal concentration in rivers and streams (Bibby &Webster-Brown, 2005; Webster, Brown, & Webster, 2000). Emissions from iron indus-tries, paint factory, cement factory and paper and board mills at Site 2 may contribute tometal concentration at downstream sites. Similarly, metals are used in various humanactivities (Khan, Din, Ihsanullah, & Zubair, 2011). More importantly, materials on wallsare more rapidly washed in urban areas, where rains contain different types of pollutants,including acidic components. Pollutant deposition enhances surface soiling and conse-quently wash-off by rain. For instance, SO2 and other acidic gases react with wallmaterials, and their products, being generally water soluble, are washed away with therain (Tang, Davidson, Finger, Striegel, 2002). This influence of the urban core was clearlyevident in the present study: the locations close to the urban core showed high concentra-tions of heavy metals.

Atmospheric deposition has also been identified as an important source of heavymetals all over the globe (Thornton & Dise, 1998). The River Ganges receives inputs fromairborne sources as well (Pandey et al., 2009, 2010). Depending upon the wind directionand atmospheric stability, atmospheric particulates may travel several kilometres down-wind from the source (Pandey et al., 2009). Vehicular emissions is the main contributor tourban particulates (Clarke, Chen, Pipitsangchand, & Azadi-Bougar, 1996). Resuspensionof land-deposited particulates further increases atmospheric loading and deposition ofheavy metals in seasonally dry tropical regions. (Pandey & Pandey, 2009a). Atmosphericloading of street dust arising from abraded roads all around the urban and suburban areasof Varanasi could substantially enhance input of particulate metals through atmosphericdeposition (Pandey et al., 2012). Particulates of crustal origin are often rich in metals suchas Zn and Fe (Gozzard, Mayes, Potter, & Jarvis, 2011; Krachler, Jirsa, & Ayromlou,2005). These, when mediated through wind-driven atmospheric loading, could travel andbe deposited at long distances downwind (Pandey et al., 2009). The predominant south-westerly wind could further raise the atmospheric transport of heavy metals towardsdownwind locations. These inputs are in addition to the urban flushing and surface runoffbeing added to the river through point and area sources. Streamflow restricts cross-streamlateral mixing of surface-fed materials in rivers, unlike in lentic systems. Under suchconditions, atmospheric deposition could be considered a major factor responsible formidstream heavy-metal contamination of the Ganges River. In a recent study (Pandeyet al., 2010), we found that massive amounts of Cd (0.78–18.65 g ha−1 yr−1), Cr (0.48–6.28 g ha−1 yr−1), Zn (152.7–447.50 g ha−1 yr−1) and many other metals are continuouslybeing added to the Ganges River through atmospheric deposition. Midstream samplescollected at each site downstream within the study stretch may include atmosphericdeposition of metal particulates added at sites upstream of the site in question. Thus,

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the aerial inputs, which are continuing to rise in developing countries like India, may alsocontribute sizeably to surface-water contamination by potentially toxic metals.

Based on the distribution of sample PC scores, three major sectors can be identified toexplain source-link relationships. These include: Adpr (Site 1), situated upstream andaway from the urban core and characterized by lowest ranges of all heavy metals; Rjusand Rjds (Sites 7 and 8), characterized by strong influence of urban core and downstreammixing, including influence of a tributary at Site 8 with the highest ranges of heavymetals; and the rest of the sampling locations, with moderate ranges of metal concentra-tions distributed between these two extreme sectors. On PCA ordinates, the Adpr site islocated in a direction opposite from Rjus and Rjds, suggesting a poor relation betweensource input variables. The data indicate that Adpr and Rjds are the two most importantsampling locations which can be used as predictors of variability as well as of urban coreand non–urban core influences. Further, with respect to metals, Fe and Zn are distributedat one side of the PC 1 axis, and the rest are distributed in the direction opposite to Fe andZn but central to the PC 2 axis, suggesting the influence of additional input variables, suchas crust-borne sources in the former and the influence of common controlling factors onthe distribution of rest of the metals (Balkis et al., 2010; Ochieng et al., 2009). Beingabundant in the earth’s crust, Fe reaches watercourses in significantly higher concentra-tions than other heavy metals (Krachler et al., 2005). When the patterns of metaldistribution are further analyzed using box-and-whisker diagrams, Zn and Fe show higherand wider ranges of distribution than the other heavy metals. For all the metals except Cd,the lower whiskers are longer than the upper ones, indicating a wider range of lowerquartiles. Such patterns of distribution suggest that the occurrence of high ranges of metalconcentrations were relatively low.

Heavy metals are highly toxic, and hence such contamination of drinking-watersources could have serious health implications. The range of concentrations observed inthe present study, however, was below the permissible limits of the Indian standard fordrinking water (Bureau of Indian Standards [BIS], 1991). The Indian standards, however,are far from the WHO standards for environmental quality, including in drinking water(Bharti, 2007). For instance, the concentrations of Ni, Cr, Mn, Cu, and Zn in midstreamwater of all the eight locations are well below their internationally recommended MACsof 20, 50, 100, 1000 and 5000 µg L−1, respectively (World Health Organization [WHO],1996). However, concentrations of Cd and Pb at seven locations and that of Fe at fourlocations were higher than their respective WHO MACs. Over 80% of all water sampleshad Cd levels above the WHO MAC; 70% had Pb above MAC; and about 50% had Feabove MAC. The data generated in this study indicate that, except for Adpr, the river-water chemistry at all study sites falls into the medium- or high-concentration zone (Edet& Offiong, 2002) – this is water not suitable for drinking.

Conclusions

Clear variations in heavy-metal concentrations in river water were observed on bothspatial and temporal scales. The data indicate a strong influence of local anthropogenicdrivers regulating metal concentrations in the Ganges River in the Varanasi region. Suchstudies are essential to better understand potential effects of seasonality and local controlson heavy-metal concentration in lotic ecosystems. The concentrations of heavy metalsobserved in this study may not harm the aquatic organisms as such; however, bioaccu-mulation coupled with biomagnification through trophic cascade is cause of concern.Further, from a human perspective it is arguably water supplies that are of greatest

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concern. Although the concentrations of Cr, Cu, Ni, Mn and Zn in midstream were wellbelow their MAC, more than 80% of water samples contained Cd, 70% contained Pb, andabout 50% contained Fe above their internationally recommended MAC. The presence ofthese metals at above MAC in river water increases the threat of adverse health effects forhuman consumers. Such issues are becoming an increasing cause of concern in waterresource management.

AcknowledgementsThe authors are grateful to the head of the Department of Botany and the coordinator of the Centreof Advanced Study in Botany, Banaras Hindu University, for facilities. AVS is grateful to theNational Academy of Sciences, India, for a Ganga Research Fellowship. We also thank the associateeditors and the reviewers for helpful comments.

ReferencesAhmad, J. U., & Goni, M. A. (2010). Heavy metal contamination in water, soil and vegetables of the

industrial areas in Dhaka, Bangladesh. Environmental Monitoring Assessment, 166(1–4), 347–357. doi:10.1007/s10661-009-1006-6

Alloway, B. J. (1995). Heavy metals in soils (2nd ed.). Chapters 6, 8, 9, and 11. UK: Chapman andHall, Glasgow.

American Public Health Association. (1998). Standard methods for the examination of water andwastewater. Washington, DC: APHA.

Balkis, N., Aksu, A., Okuş, E., & Apak, R. (2010). Heavy metal concentrations in water, suspendedmatter, and sediment from Gökova Bay, Turkey. Environmental Monitoring Assessment, 167(1–4), 359–370. doi:10.1007/s10661-009-1055-x

Beg, K. R., & Ali, S. (2008). Chemical contaminants and toxicity of Ganga River sediment from upand down stream area at Kanpur. American Journal of Environmental Sciences, 4(4), 362–366.doi:10.3844/ajessp.2008.362.366

Bharti, P. K. (2007). Why are Indian standards not strict? Current Science, 93, 1202.Bibby, R. L., & Webster-Brown, J. G. (2005). Characterisation of urban catchment suspended

particulate matter (Auckland region, New Zealand); a comparison with non-urban SPM. TheScience of the Total Environment, 343, 177–197. doi:10.1016/j.scitotenv.2004.09.041

Buffleben, M. S., Zayeed, K., Kimbrough, D., Stenstrom, M. K., & Suffet, I. H. (2002). Evaluationof urban non-point source runoff of hazardous metals entering Santa Monica Bay, California.Water Science and Technology, 45(9), 263–268.

Bureau of Indian Standards. (1991). Indian standard specification for drinking water. IS: 10500.Clarke, A. G., Chen, J. M., Pipitsangchand, S., & Azadi-Bougar, G.A. (1996). Vehicular particulate

emissions and roadside air pollution. Science of the Total Environment, 189–190, 417–422.doi:10.1016/0048-9697(96)05239-4

Edet, A., & Offiong, O. E. (2002). Evaluation of water quality pollution indices for heavy metalcontamination monitoring. A study case from Akpabuyo-Odukpani area, lower cross river basin(Southeastern Nigeria). Geojournal, 57, 295–304. doi:1023/B:GEJO.0000007250.92458.de

Gozzard, E., Mayes, W. M., Potter, H. A. B., & Jarvis, A. P. (2011). Seasonal and spatial variation ofdiffuse (non-point) source zinc pollution in a historically metal mined river catchment, UK.Environmental Pollution, 159, 3113–3122. doi:10.1016/j.envpol.2011.02.010

Jain, C. K. (2002). A hydrochemical study of a mountainous watershed: The Ganga, India. WaterResearch, 36, 1262–1274. doi:10.1016/S0043-1354(01)00327-X

Jeng, H. A. C., Englande, A. J., Bakeer, R. M., & Bradford, H. B. (2005). Impact of urbanstormwater runoff on estuarine environmental quality. Estuarine Coastal and Shelf Science,63, 513–526. doi:10.1016/j.ecss.2004.11.024

Kar, D., Sur, P., Mandai, S. K., Saha, T., & Kole, R. K. (2008). Assessment of heavy metal pollutionin surface water. International Journal of Environmental Science and Technology, 5, 119–124.doi:10.1007/BF03326004

Khan, S. A., Din, Z. U., Ihsanullah, & Zubair, A. (2011). Levels of selected heavy metals indrinking water of Peshawar city. International Journal of Science and Nature, 2, 648–652.

12 A.V. Singh and J. Pandey

Dow

nloa

ded

by [

Ban

aras

Hin

du U

nive

rsity

BH

U]

at 0

2:55

04

June

201

4

Krachler, R., Jirsa, F., & Ayromlou, S. (2005). Factors influencing the dissolved iron input by riverwater to the open ocean. Biogeosciences, 2, 311–315. doi:10.5194/bg-2-311-2005

Lee, H., Lau, S. -L., Kayhanian, M., & Stenstrom, M. K. (2004). Seasonal first flush phenomenon ofurban stormwater discharges. Water Research, 38, 4153–4163. doi:10.1016/j.watres.2004.07.012

Ochieng, E. Z., Lalah, J. O., & Wandiga, S. O. (2009). Anthropogenic sources of heavy metals inthe Indian Ocean coast of Kenya. Bulletin of Environmental Contamination and Toxicology, 83,600–607. doi:10.1007/s00128-009-9807-4

Pandey, J., & Pandey, U. (2009a). Accumulation of heavy metals in dietary vegetables andcultivated soil horizon in organic farming system in relation to atmospheric deposition in aseasonally dry tropical region of India. Environmental Monitoring and Assessment, 148, 61–74.doi:10.1007/s10661-007-0139-8

Pandey, J., & Pandey, U. (2009b). Atmospheric deposition and heavy metal contamination in anorganic farming system in a seasonally dry tropical region of India. Journal of SustainableAgriculture, 33, 361–378. doi:10.1080/10440040902834954

Pandey, J., Pandey, R., & Shubhashish, K. (2009). Air–borne heavy metal contamination to dietaryvegetables: A case study from India. Bulletin of Environmental Contamination and Toxicology,83(6), 931–936. doi:10.1007/s00128-009-9879-1

Pandey, J., Pandey, U., & Singh, A. V. (2014). Impact of changing atmospheric deposition chemistryon carbon and nutrient loading to Ganga River: Integrating land–atmosphere–water componentsto uncover cross-domain carbon linkages. Biogeochemistry, doi:10.1007/s10533-014-9957-2

Pandey, J., Shubhashish, K., & Pandey, R. (2010). Heavy metal contamination of Ganga River atVaranasi in relation to atmospheric deposition. Tropical Ecology, 51(2S), 63–71.

Pandey, R., Shubhashish, K., & Pandey, J. (2012). Dietary intake of pollutant aerosols via vege-tables influenced by atmospheric deposition and wastewater irrigation. Ecotoxicology andEnvironmental Safety, 76, 200–208. doi:10.1016/j.ecoenv.2011.10.004

Purushothaman, P., & Chakrapani, G. J. (2007). Heavy metals fractionation in Ganga Riversediments, India. Environmental Monitoring and Assessment, 132, 475–489. doi:10.1007/s10661-006-9550-9

Schwartz, J. (1994). Air pollution and daily mortality: A review and meta – analysis. EnvironmentalResearch, 64, 26–35.

Siegel, F. R. (2002). Environmental geochemistry of potentially toxic metals. Berlin: Springer-Verlag.

Singh, M., & Singh, A. K. (2007). Bibliography of environmental studies in natural characteristicsand anthropogenic influences on the Ganga River. Environmental Monitoring Assessment, 129,421–432. doi:10.1007/s10661-006-9374-7

Tang, W., Davidson, C. I., Finger, S., & Striegel, M. F. (2002). Wind-driven Rain on a TallLimestone Building: Washoff of Soiling caused by Pollutant Deposition. In R. Van Grieken& Y. Shevah (Eds.), Proceedings, of int. sym. atmospheric deposition and its impact onecosystems (pp. 55–69). Antwerp: University of Antwerp Press.

Thornton, G. J. P., & Dise, N. B. (1998). The influence of catchment characteristics, agriculturalactivities and atmospheric deposition on the chemistry of small streams in the English LakeDistrict. The Science of the Total Environment, 216, 63–75. doi:10.1016/S0048-9697(98)00138-7

Voutsa, D., Grimanis, A., & Samara, C. (1996). Trace elements in vegetables grown in an industrialarea in relation to soil and air particulate matter. Environmental Pollution, 94, 325–335.doi:10.1016/S0269-7491(96)00088-7

Webster, J. G., Brown, K. L., & Webster, K. S. (2000). Source and transport of trace metals in theHatea River catchment and estuary, Whangarei, New Zealand. New Zealand Journal of Marineand Freshwater Research, 34, 187–201. doi:10.1080/00288330.2000.9516925

World Health Organization. (1996). Guidelines for drinking water quality: (2ed. Vol. 2). Healthcriteria and other supporting information. Geneva: WHO.

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