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Heavy metals in freshly deposited sediments of the Gomati River (a tributary of the Ganga River): effects of human activities M. Singh 7 A. A. Ansari 7 G. Müller 7 I. B. Singh

Abstract The concentrations of various metals (Cr, Cu, Co, Fe, Mn, Ni, Pb, Zn, and Cd) were determined in recently deposited surface sediments of the Gomati River in the Lucknow urban area. Markedly elevated concentrations (milligrams per kilogram) of some of the metals, Cd (0.26–3.62), Cu (33–147), Ni (45–86), Pb (25–77), and Zn (90–389) were observed. Profiles of these metals across the Lucknow urban stretch show a progressive downstream increase due to additions from 4 major drainage networks discharging the urban effluents into the river. The degree of metal contamination is compared with the local background and global standards. The geoaccumulation index order for the river sediments is Cd`Zn`Cu`Cr`Pb. Significant correlations were observed between Cr and Zn, Cr and Cu, Cu and Zn and total sediment carbon with Cr and Zn. This study reveals that the urbanization process is associated with higher concentrations of heavy metals such as Cd, Cu, Cr, Pb, and Zn in the Gomati River sediments. To keep the river clean for the future, it is strongly recommended that urban effluents should not be overlooked before their discharge into the river. Key words Heavy metals 7 Sediment India

Received: 16 February 1996 7 Accepted: 29 February 1996 G. Müller (Y) 7 M. Singh 1 Institute of Environmental Geochemistry, University of Heidelberg, D-69120 Heidelberg, Germany I. B. Singh Department of Geology, University of Lucknow, Lucknow 226007, India A. A. Ansari 1 Institute of Geology and Mineralogy, Erlangen Nürnberg University, D-91054 Nürnberg, Germany Present address: 1 Department of Geology, University of Lucknow, Lucknow 226007, India

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Environmental Geology 29 (3/4) February 1997 7 Q Springer-Verlag

Introduction The investigation of sediments from the hydrosphere has recently become a major subject of interest in research on aquatic systems, as they reflect the current quality of the system and provide information on the impact of man. Sediments are increasingly recognized as carriers and possible sources of contaminants in the system. Human activities (urbanization, industrialization, mining, etc.) promote the accumulation of polluted sediments in the nearby river system, which is considered to be a safe disposal site for contaminated sediments. Contaminants in river systems can be investigated by analyzing either the water and the suspended material or the sediments. The measurements of pollutants in the water are not conclusive due to water discharge fluctuations and low residence time. The same holds true for the suspended material. In this situation, the study of the sediments plays an important role, as they have a long residence time. River sediments, therefore, are important sources for the assessment of man-made contamination in rivers (Förstner and Wittmann 1983; Müller 1979). In the last few years, much attention has been paid to geological studies of the Gomati River and its sediments (Kumar and Singh 1978; Kumar 1989; Gupta and Subramanian 1994). The present research deals with the heavy metal distribution in recently deposited Gomati River sediments from the Lucknow urban area. In order to understand the geochemical effects of urban effluents on the natural river sediment, the chemical composition of river sediment from urban and nonurban areas needs to be known. In 1987, the river sediments were reported as unpolluted with heavy metals (Kumar 1989). Our geochemical study focuses on the present status (in 1994) of the river sediments with respect to heavy-metal pollution. It will also help in understanding the ways in which the human activities control the metal distribution in river sediments. Study site, geological background, and nature of Gomati River water The Gomati River, a tributary of the Ganga River, originates from the swampy forested area located near the south of the Himalayan foothills. The river flows in the great alluvial plain, which is of Pleistocene–Holocene origin, and redistributes the primary weathered sediments of the Gangetic alluvial plain derived from the Himalaya

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Table 1 Physicochemical characteristics of Gomati River water in Lucknow 1 pH Conductvity (mS cm P1) Total suspended matter (mg l P1) Total dissolved solid (mg l P1) P1 ) HCOP 3 (mg l 1

8.1– 8.4 320 –350 18 – 26 415 –440 300

After Gupta and Subramanian 1994

bonate is the dominant ion, followed by calcium and sodium. Monsoon hydrographic and physicochemical characteristics of the river water play a prominent role in regulating metal behavior in the river sediments. It is with this background that an attempt has been made to define the present status of the heavy metals distribution in the Gomati River sediments and to quantify the degree of metal pollution.

Materials and methods A 15-km-long stretch of the Gomati River was selected for the present study. Freshly deposited sediment samples were collected from 10 stations along the river bank in the Lucknow urban area and from 4 stations from the urban effluents. These sampling locations are shown in Fig. 1. The uppermost stream station, apparently outside of Fig. 1 the urban zone, provided samples for the background deLocation map of Lucknow with sampling sites (G1–G10 for termination. In order to minimize the grain-size dependGomati River sediments and U1–U4 for Lucknow urban encies of metal concentration, a grain size fraction effluents) ~20 mm was used in this study. A nylon sieve and distilled water were used to separate the required sediment fraction from the collected samples. The mineralogy was (Kumar and Singh 1978). It flows over 750 km in a SE di- determined by x-ray diffraction analysis with a Siemens rection and joins the Ganga River near Varanasi. In the D 500 diffractometer; 100 mg of sieved and dried samples middle of its course, the river passes through the Luckwere digested with 3 ml perchloric acid, 3 ml nitric acid, now urban area (Fig. 1). Lucknow is a capital city in the and 4 ml hydrofluoric acid in closed Teflon beakers at Gangetic plain, with an urban population of more than 150 7C for 5 h. These solutions were heated once again at 1.6 million and some industrial units. The urban ef180 7C for 11 h to fume all the acid from the solutions. fluents, including industrial and municipal waste, flow After the fuming process, the residues were treated with into the freshwater river through small open drainages. 1 ml nitric acid and distilled water to make solutions for These drainages are Kadra Nala, Daliganj Nala, New Hy- atomic absorption spectrophotometry. For quality conderabad Nala, and Haidergarth Canal. The river is chartrol, standard STSD-3 and analytical blanks were preacterized by sluggish flow throughout the year, except pared and analyzed using the same procedures and readuring the monsoon season, when heavy rainfall causes a gents. Total carbon in the sediment samples was analyzed manifold increase in the runoff. Most of the sediments using the carbon sulfur determinator model CS-225, Leco are transported during high river discharge, in the mon- Corporation. soon period. The postmonsoon period is associated with the depositional phase of the river due to low water discharge. At Lucknow, the maximum and minimum values Results and discussion for the runoff are 7 and 2 m 3 s P1, respectively (Kumar and Singh 1978). Physicochemical characteristics of the Gomati River sediments Gomati River water were analyzed in detail by Gupta and Subramanian (1994), and some of their data are present- The river sediments are made up of fine sand, silt, and ed in Table 1. The river water is alkaline in nature. Bicar- clay. The fine silt and clay (~20 mm fraction) content in


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the sediment samples ranges from 6 to 40% with an average of 20%. The XRD analysis shows the dominance of quartz, followed by feldspars and mica (Fig. 2). The clay fraction shows illite as the main mineral along with kaolinite and montmorillonite (Kumar and Singh 1978).

Fig. 2 XRD analysis of the Gomati River sediments from Lucknow urban center

Heavy metals in sediments Metal concentrations in the Gomati River sediments at Lucknow area show varying and different behavior influenced by urbanization. The results of the chemical analysis of the samples are presented in the Table 2. Figure 3 shows significant downstream variations in the total metal levels and total carbon in the river sediments of the Lucknow urban area. The four bars in each metal profile represent the downstream load from the urban ef-

Table 2 Heavy metal concentrations in Gomati River sediments (~20 mm fraction) in Lucknow urban area

Average Median Minimum Maximum

Cd

Cu

Co

Cr

Fe

Mn

Ni

Pb

Zn

1.30 0.61 0.26 3.62

70 55 33 147

21.1 20.3 18.6 25.9

160 155 115 204

5.16 5.12 4.32 6.11

600 620 845 440

64 61 45 86

41 30 25 77

181 137 90 389

Fig. 3 Downstream profiles of heavy metal concentrations and total sediment carbon in ~20 mm fraction of the recently deposited Gomati River sediments from the Lucknow urban area. Zero kilometer distance is the point of entry of the river into the Lucknow urban area. Bars represent the downstream urban load

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fluents into the river. Downstream profiles of these heavy metals show interesting features at sampling stations G5, G6, and G9, where the river receives waste water effluents from urban drains U2, U3, and U4 (Fig. 1). Total metal concentrations in the fraction ^20 mm of the sediments vary in the range of 115–204 for Cr, 440–845 for Mn, 43 200–61 100 for Fe, 18.6–25.9 for Co, 45–86 for Ni, 33–147 for Cu, 90–389 for Zn, 25–77 for Pb, and 0.26– 3.62 mg kg P1 for Cd. At station G5, Co, Cr, and Ni concentrations decrease, whereas Cd, Cu, Pb, Zn, and total C concentrations increase downstream. At station G9, the river receives urban effluents from U4 drainage that cause the increase in all heavy metal concentrations (except Fe and Mn). The variation in the metal concentrations at the G5, G6, and G9 stations are possibly due to variation in the water chemistry of the river at the urban Nala confluences. Cd, Cu, Cr, Pb, and Zn concentrations of urban effluents indicate significant anthropogenic inputs to the river. This causes the increase of metal concentrations in the downstream sediments. While Fe and Co levels remain constant, Mn concentrations continuously drop in the downstream section. Ni concentrations drop rapidly after the confluence of Khadra Nala (U1) and subsequently in-

crease again to reach previous levels within the urban limits. Total sediment carbon concentrations gradually increase downstream. Extremely high Cu, Cr, and Zn levels are reported in the Hydergarh Canal sediments, Pb levels in the New Hyderabad Nala sediments, and CD levels in the Khadra Nala sediments. The average metal contents of the sediments are compared with the standard shale values as well as with the average content of Neckar River sediments, a tributary of the Rhine River in Germany (Table 3). The uppermost sediment sample (G1) is used for the natural background values. The metal content in nonurban sediments is in good agreement with the shale standard. The data show an alarming enrichment of certain heavy metals in the urban effluents. This metal-rich effluent flows into the river and causes the elevation of some of the metals in the river sediments. The Co, Cr, and Ni concentrations in the Gomati River sediments are as high as in the Neckar River sediments. Interelement relationship Table 4 shows the correlation matrix for heavy metals and total sediment carbon in the sediments. A good correlation among Cd, Cu, Cr, Ni, and Zn and also with se-

Table 3 Comparison of heavy metal concentrations in Gomati River sediments with their urban sediments, average shale, and Neckar River sediments Concentration 1

Average shale 2 Gomati sediments 3 Urban effluents 4 Urban sediments 4 Neckar sediments 5

Cd

Cu

Co

Cr

Fe

Mn

Ni

Pb

Zn

0.30 0.26 1.11 1.30 1.81

45 33 142 70 108

19.0 18.9 19.2 21.1 11.2

90 115 219 160 123

4.60 4.55 4.30 5.16 2.37

850 665 456 600 496

68 59 73 64 44

20 25 66 41 74

95 90 429 181 370

1

4

In milligrams per kilogram, except Fe is in percentage Turekian and Wedepohl (1961) 3 Background values (outsite of the Lucknow urban area)

Average values have been rounded off Müller and others (1993) investigated during 1990, a tributary of the Rhine River in Germany

2

5

Table 4 Interelement relationship of Gomati River sediments (correlation coefficient matrix) 1

Fe Mn Ni Co Pb Zn Cu Cr Cd C

Fe

Mn

Ni

Co

Pb

Zn

Cu

Cr

Cd

C

1 0.72 0.01 0.11 0.75 P0.40 P0.38 P0.38 P0.42 P0.61

1 P0.27 0.07 0.43 P0.58 P0.59 P0.59 P0.59 P0.69

1 0.26 0.50 0.86 0.87 0.83 0.12 0.69

1 0.17 0.19 0.14 0.16 P0.27 0.02

1 0.13 0.16 0.14 P0.18 P0.09

1 0.91 0.99 0.41 0.94

1 0.90 0.45 0.84

1 0.49 0.95

1 0.55

1

1

Significant at 90% probability and total number of samplesp14 (10 for the Gomati River sediment and 4 for urban effluent sediment)


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Fig. 4 Scatter plot for Zn against Cu and Cr and total sediment carbon against Cr and Zn

diment carbon was observed, indicating their common sink in the sediments. Some of these relationships are also shown in Fig. 4. Negative correlations of Fe, Mn, and Pb with sediment carbon indicate their hydroxides form in the sediments.

of quantification of pollution (Förstner and Wittmann 1973; Müller 1979). Metal ratios with respect to average shale for the Gomati River sediments in the Lucknow urban area show various degrees of enrichment (Table 5). Except for Cr and Pb, all the ratios are less than 1 before the river enters the Lucknow urban area, whereas in downstream sediments, all the heavy metals show a ratio Quantification of sediment pollution of more than 1. Cd shows the maximum value of 12. Metal ratios Many authors prefer to express the metal Average enrichment factors were also calculated with reratio with respect to average shale to represent the degree spect to the sample collected from outside the area of urTable 5 Metal ratios with average shale in Gomati River sediments

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Downstream location

Cd

Co

Cr

Cu

Fe

Mn

Ni

Pb

Zn

G1 G2 G3 G4 G5 G6 G7 G8 G9 G10

0.87 1.00 1.50 2.53 7.80 1.40 5.50 1.00 12.07 9.73

0.99 1.21 1.22 1.15 1.03 1.37 0.98 1.03 1.08 1.05

1.28 1.58 1.71 2.04 1.73 2.04 1.62 1.67 2.27 1.79

0.73 0.89 1.11 1.20 1.93 1.22 1.44 1.07 3.27 2.62

0.99 1.22 1.21 1.26 1.01 1.33 1.03 1.19 1.03 0.94

0.78 0.99 0.71 0.79 0.56 0.75 0.59 0.84 0.52 0.52

0.86 1.16 1.19 1.27 0.66 0.78 0.71 0.87 0.94 1.06

1.25 1.35 1.45 1.35 2.35 1.45 2.45 1.50 3.85 3.35

0.95 1.11 1.27 1.46 2.53 1.42 1.76 1.20 4.09 3.31


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Table 6 Igeo classes with respect to sediment quality (Müller 1979)

Fig. 5 Human impact on heavy metal distributions in terms of enrichment factors in Gomati River sediments at Lucknow

ban influence. The calculated enrichment factors are 2 for Pb and Cr, 4 for Zn and Cu, and 11 for Cd. The enrichment factors for Pb, Zn, Cu, and Cd, indicate an anthropogenic source of heavy metals in the river sediments (Fig. 5). Negative enrichement of Fe and Mn may be explained by Fe/Mn oxides providing adsorbing sites for other heavy metals. Geoaccumulation index The geoaccumulation index proposed by Müller (1979) for the quantification of metal accumulation in sediments was also calculated for the Gomati River sediments. It is expressed as: Igeoplog2 Cn /1.5 Bn where Cn is the measured concentration; Bn is the background value (average shale) of element n; and 1.5 is the background matrix correction factor. The factor 1.5 is used for possible variations in the background data due to lithogenic effects. The geoaccumulation index consists of seven grades ranging from unpolluted to very highly polluted (Table 6). Class 6 indicates a `64-fold enrichment above the background values. Table 7 presents the geoaccumulation index for the quantification of heavy metal accumulation in the river sediments. The Igeo class for the river sediments in Lucknow varies downstream. Fe, Mn, Ni, and Co remain in class 0. Pb and Cr are mostly in class 1, whereas Cu and Zn in-

Igeo class

Sediment quality

0 1 2 3 4 5 6

unpolluted unpolluted to moderately polluted moderately polluted moderately to highly polluted highly polluted highly to very highly polluted very highly polluted

crease from 1 to 2 and Cd attains a value of 4. Based on the geoaccumulation indices, the Gomati River sediments in Lucknow urban area are considered unpolluted with respect to Co, Ni, and Fe; moderately polluted with Cu, Zn, Cr, and Pb; and highly polluted with Cd. Cumulative presentation For the cumulative presentation of human impact on the river sediments, Fig. 6 shows a synthetic view of the dispersion of the five heavy metals (Cr, Cd, Cu, Pb, and Zn) in the river sediments. For each metal, the average shale concentration is brought back to 100. Thus the total average shale concentration will be 500 for these five metals. In the same way, the sum of the concentrations of these five metals in each sample represents the cumulative effect of urbanization on the Gomati River sediments. The basic nature of the river water may induce accumulation of these heavy metals in the sediments. Highly polluted effluents from the urban area are the main cause for the pollution of the river sediments. A comparison of heavy metal concentrations with their natural background reveals that metal enrichments are attributable to anthropogenic influences rather than natural erichment in the Lucknow urban area. It is estimated that `75% of Cd, 50% of Cu and Zn, and `25% of Cr and Pb concentrations in the sediments are derived from anthropogenic input.

Table 7 Geoaccumulation index of Gomati River sediments (after Müller 1979) Downstream location

Cd

Co

Cr

Cu

Fe

Mn

Ni

PB

Zn

G1 G2 G3 G4 G5 G6 G7 G8 G9 G10

0 0 0 1 3 0 2 0 4 2

0 0 0 0 0 0 0 0 0 0

0 1 1 1 1 1 1 1 1 1

0 0 0 0 1 0 0 0 2 1

0 0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 1 1

0 0 0 0 1 0 1 0 2 2


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around 2 for Pb and Cr, 4 for Zn and Cu, and 11 for Cd, indicating the anthropogenic source of these heavy metals in the river sediments. Metals (Cr, Zn), (Cr, Cu), (Cu, Zn) and total sediment carbon with Cr and Zn show significant correlations. Based on the geoaccumulation indices, the river sediments can be treated as moderately polluted with Cu, Zn, Cr, and Pb and highly polluted with Cd. It is evident from the present study that the urbanization process has a great influence on transportation and accumulation of these toxic heavy metals in the Gomati River. The present data can provide useful information for pollution control strategies and urban environmental planning in Lucknow and other urban centers located along the Ganga River system.

Fig. 6 Cumulative metal enrichment in Gomati River sediments at Lucknow

Acknowledgements M. S. and A. A. A. are thankful to Prof. S. K. Singh, Prof. M. P. Singh and Prof. S. Kumar, Department of Geology, University of Lucknow, India, for constant encouragement and help during the course of investigation. The field assistance of Mr. Dhurv Sen and Mr. Jai Narayan is also appreciated. Thanks are also extended to Stefan Rheinberger and Silvia Marhoffer for their help during geochemical analysis. Dr. Jörg Matschullat is acknowledged for helpful suggestions on an early version of the manuscript. M. S. and A. A. A. are grateful to Deutscher Akademischer Austauschdienst, Bonn (DAAD) for financial support for this research, which was carried out at the Institute for Environmental Geochemistry, University of Heidelberg, Germany.

References

Fig. 7 Sources of heavy metals in Gomati River sediments at Lucknow

Conclusions Like other known pollution episodes around urban regions where rivers are affected by human activities, the Gomati River in Lucknow presents a good example that can be used to compare and contrast the effect of urbanization on the distribution of heavy metals in the river sediments. Recently deposited Gomati River sediments show increased heavy metal concentrations due to urban waste effluent discharged into the river. Compared with background values, the average enrichment factors are

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