Geochemical assessment of heavy metals pollution in surface sediments of Vellar and Coleroon estuaries, southeast coast of India

MPB-08198; No of Pages 11 Marine Pollution Bulletin xxx (2016) xxx–xxx

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Geochemical assessment of heavy metals pollution in surface sediments of Vellar and Coleroon estuaries, southeast coast of India S. Nethaji ⁎, R. Kalaivanan, Arya Viswam, M. Jayaprakash Climate Change and Environmental Research Group (CERG), Department of Applied Geology, University of Madras, Chennai 600 025, Tamil Nadu, India

a r t i c l e

i n f o

Article history: Received 22 August 2016 Received in revised form 14 November 2016 Accepted 19 November 2016 Available online xxxx Keywords: Heavy metals Pollution indices Contamination factor Enrichment factor Geo-accumulation index

a b s t r a c t Surface sediments were collected from Vellar and Coleroon estuaries for determine sediment texture, calcium carbonate, organic matter and heavy metals. Pollution indices such as pollution load index (PLI), contamination factor (CF), enrichment factor (EF) and geo-accumulation index (Igeo) were done for this study to know the level of heavy metals pollution in the estuarine ecosystem. Pearson correlation matrix and factor were used to assess the relationship and source of heavy metals in the estuarine sediments. The results of PLI values reveal that the study area was polluted by all the heavy metals. The calculated values of CF and Igeo followed the decreasing order Cu N Ni N Pb N Co N Cr N Zn N Mn N Fe and illustrate that Cu, Ni and Pb are contaminated due to anthropogenic sources in both estuaries. Correlation and factor analysis suggest that Fe\\Mn oxyhydroxides, organic matter and fine particles are responsible for high concentration of heavy metals. © 2016 Published by Elsevier Ltd.

Estuarine and coastal environments receive huge amounts of harmful heavy metals, and are engaged in numerous ways into the environment predominantly as it drains into the aquatic environments, especially by industrial effluents. The toxicity of those heavy metals achieves greater importance as they accumulate in sediments (Jayaprakash et al., 2014). Generally heavy metals, enter the aquatic environment through atmospheric deposition, erosion of geological matrix or owing to anthropogenic activities caused by industrial discharges, domestic sewage and mining wastes (Solai et al., 2013). The estuaries allow the fine materials to deposits of generally enriched with metals and organic matter (Cook et al., 2007; Anithamary et al., 2013). The estuarine sediments undergo various physio-chemical changes due to the contribution of rivers and seawater, along with an increasing population, fishing activity and other anthropogenic activities (Ramanathan et al., 1999) which can provide valuable data regarding to modern human effects on the geological cycle (Chandrasekaran et al., 2013). Discharging of industrial and urban wastes into water bodies directly disturbs the equilibrium among the metals in sediments (Yu et al., 2001; Filgueiras et al., 2004). The estuarine environments could severely disturb by heavy metals due to industrial wastes and anthropogenic activities, as they tend to act as sinks for fine, pollutants reactive sediments (Magesh et al., 2013). The hydrodynamic setting of the estuarine region, which helps to heavy metals to be deposited in the bottom of estuarine region (Krom et al., 2009; Fernandes et al., 2011). The accumulation of heavy metals in estuaries, which may leads to severe ⁎ Corresponding author. E-mail address: [email protected] (S. Nethaji).

environmental problems. Subsequently heavy metal concentration in sediment can be used to expose the past and intensity of pollution of the region (Sekabira et al., 2010). Most of the heavy metals trapped by sediments and forming stable complexes with sediment texture, organic matter and Fe\\Mn oxyhydroxides (Rajendran et al., 1992; Jonathan et al., 2004; Dhanakumar et al., 2013). The heavy metals accumulation in coastal environment has significantly enriched in recent times due to anthropogenic activities (Buggy and Tobin, 2008; Dessai and Nayak, 2009; Botte et al., 2010; Yang et al., 2012). Several indices have been established to evaluate the contamination level of heavy metal in sediments (Spencer and Macleod, 2002; Caeiro et al., 2005), such as pollution load index, enrichment factor and geo-accumulation index (Igeo). These indices will focus on sediment contamination in terms of heavy metals and its potential sources. Many researchers have much attention with concern to geochemistry of Vellar and Coleroon estuarine sediments (Seralathan and Seetharamasamy, 1987; Subramanian et al., 1989; Purvaja and Ramesh, 2000; Alagarsamy and Zhang, 2010; Anithamary et al., 2013; Dhanakumar et al., 2013; Santhi and Prabhahar, 2014; Venkatramanan et al., 2015). This ecosystem is perfect location to study a number of processes such as evaporation, mixing, dissolution and chemical exchange between water and sediments which are significant in understanding hydrogeochemical processes (Ramanathan et al., 1999). Sediment characteristics such as sediment texture, organic matter content, calcium carbonate and heavy metal determination, which are helps to find out bioavailability and potential toxicity (Du Laing et al., 2002) of the ecosystem. Most of the previous studies carried out either in Vellar or Coleroon Estuary. Hence, the

http://dx.doi.org/10.1016/j.marpolbul.2016.11.045 0025-326X/© 2016 Published by Elsevier Ltd.

Please cite this article as: Nethaji, S., et al., Geochemical assessment of heavy metals pollution in surface sediments of Vellar and Coleroon estuaries, southeast coast of India, Marine Pollution Bulletin (2016), http://dx.doi.org/10.1016/j.marpolbul.2016.11.045

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S. Nethaji et al. / Marine Pollution Bulletin xxx (2016) xxx–xxx

present research is focused on both Vellar and Coleroon estuaries by comprehensive studies on geochemistry of sediment characteristics and potential anthropogenic impact of heavy metals. This study has been conducted in Vellar (11°28′ to 11°31′ N; 79°45′ to 79°47′ E) and Coleroon estuaries (11°21′ to 11°23′ N; 79°46′ to 79°50′ E). The Vellar River originates in Chitteri Hills (Eastern Ghats) at an elevation of 900 m, and it has a total length of 210 km through Salem and Cuddalore districts in Tamil Nadu. Coleroon is one of the major branches of Cauveri River, which splits from Cauvery near Srirangam. It flows about 150 km and empties into the Bay of Bengal. Both estuaries are geographically located in Cuddalore District along the southeast coast of Tamil Nadu, India and it is a portion of Cauvery River basin. The Vellar and Coleroon estuaries open into Bay of Bengal. The study area experiences tropical climatic condition with a temperature ranges from 18 to 36 °C. The northeast monsoon provides greater portion of the annual precipitation (1200 mm). Vellar and Coleroon rivers flow in sub parallel pattern to each other and these rivers are ephemeral and carry flood during monsoon. The geology of the study area is predominantly made up of Precambrian rocks, peninsular granitic gneiss, charnockites, quartzite, limestone, Closepet granite and alluvium (Ramanathan et al., 1993; Madras Science Foundation, 2000). On its course, both rivers receive numerous tributaries, urban drainages, and industrial effluents that are eventually dumped into the estuarine regions (Dhanakumar et al., 2013). Some of these tributaries are extensive outflow to the agricultural grounds. These estuaries fringed with variety of mangrove patches, mud flat shrubs which is breeding ground for number of marine and brackish water organisms. Surface sediment samples were collected from 24 selected stations in Vellar and Coleroon estuaries during August 2015, in each estuary 12 stations have been selected according to various locations in which

sea water mixing with fresh water near Parangipettai (Porto Novo) and Pazhaiyar as shown in Fig. 1. The geographical locations of the sampling stations were marked using a hand-held GPS. Sediment samples were collected by Van Veen grab sampler. From the grab sampler, sediment was collected by using plastic spatula and transferred into precleaned polyethylene bags. The sediment samples were air dried, homogenized to analyses the sediment texture and heavy metals concentration. After coning and quartering of sediment samples, sand and mud (silt + clay) were estimated following the method of Ingram (1970), by using 230 (63 μm) ASTM mesh. Carbonate content (CaCO3) was measured by following the procedure of Loring and Rantala (1992), using hydrochloric acid, and organic matter (OM) in the sediments was determined following the technique of Gaudette et al. (1974), with the help of potassium dichromate, silver sulphate and concentrated sulphuric acid. The heavy metals (Fe, Mn, Cr, Cu, Pb, Zn, Ni and Co) were determined after preliminary treatment and total decomposition of sediments subsequent procedure of Tessier et al. (1979). The finely ground (with help of an agate mortar and pestle) sediment sample was digested with acid mixture of 4:1 HF and HClO4 on a hot plate up to 100 °C in Teflon bomb. The residual sediment was then dissolved in concentrated HNO3 and heated again. After ensuring complete digestion of the sediment sample, the solution from the Teflon bomb were transferred into acid washed polypropylene volumetric flaks. Finally the solution was made up of 100 ml with ultrapure water. The final solution was analyzed for heavy metals using Atomic Absorption Spectroscopy (AAS - Perkin Elmer AAnalyst 700) equipped with a deuterium background corrector in the Department of Applied Geology, University of Madras. For quality assurance, appropriate internal chemical standards (Merck Chemicals, Germany) were used to calibrate the instrument. Likewise, the reagents

Fig. 1. Location map of the study area with sample locations in Vellar and Coleroon estuary, SE Coast of India.

Please cite this article as: Nethaji, S., et al., Geochemical assessment of heavy metals pollution in surface sediments of Vellar and Coleroon estuaries, southeast coast of India, Marine Pollution Bulletin (2016), http://dx.doi.org/10.1016/j.marpolbul.2016.11.045

S. Nethaji et al. / Marine Pollution Bulletin xxx (2016) xxx–xxx

used were analytical grade of high purity. Standard reference materials (MESS-1) obtained from the National Research Council of Canada were used in the present study to ensure the accuracy of the analyses, which were found to be within 5% (Table 1), which exceeded the values reported by Jayaprakash et al. (2014). The consequent results were determined for correlation coefficients (SPSS 19) to find out the inter relationship between sediment characteristics and heavy metals. The distribution pattern of sediment textural parameter (sand & mud), calcium carbonates, organic matter and heavy metals (Fe, Mn, Cr, Cu, Pb, Zn, Ni and Co) done by Surfer (version 9) and were presented in Figs. 2 and 3 for both Vellar and Coleroon estuaries respectively. The spatial distribution pattern of sediment texture and heavy metals in the study area shows variations respect to sampling stations is due to flow conditions of the estuaries. The relative abundance of sand, mud, CaCO3, organic matter and heavy metals were presented in Table 2. Sand content ranges from 37.4 to 82.6% and 31.6 to 96.4% with a mean of 62.43 and 67.92% in Vellar and Coleroon estuary respectively. The mud in the study area ranges from 17.4 to 62.6% and 3.6 to 68.4%. Thus, most of the samples dominated by sand and only few samples show higher concentration of mud. Generally, mouth of the estuaries have higher concentration of sand is due to tidal effects (Muthuraj and Jayaprakash, 2008). The spatial distribution map of mud showing higher concentration of mud at middle portion of the estuaries, it is due to low energy and mixing of fresh water with marine water fine particles that settle down in bottom (Thomson-Becker and Luoma, 1985). Higher concentration of sand fractions were found near the estuarine mouth is mainly due to low energy conditions in the estuarine coastal water interaction, where the suspension takes place and are transport the finer particles in to deeper region (Jayaprakash et al., 2014). The estimated value of CaCO3, in surface sediments of Vellar and Coleroon estuaries ranges from 1 to 5 and 1.5 to 5% with a mean of 2.83% (in both estuaries) respectively. The concentration of carbonates was high in Coleroon riverine side suggesting that they are brought down by terrestrial input of calcareous materials from limestone around Ariyalur region. The low value of CaCO3 in the mid portion of both estuaries is due to fine nature of sediment texture, which is do not support biological activity. The organic matter distribution varies from 0.4 to 1.69% with a mean of 0.84% in Vellar estuary, in Coleroon estuary it is ranges from 0.2 to 1.46% with a mean of 0.75%. The organic matter in the study area was mostly low in both estuaries, because the dominance of sand but the organic matter is high where the fine particle (mud) also higher. Ramanathan et al. (1999) also reported Vellar and Coleroon estuaries have low organic matter when compared to Pichavaram mangrove region. The relatively high OM in mid portion of the estuaries due to terrigenous input and industrial wastes adsorbed by the fine particles and greater surface area of fine particles supports the deposition of organic debris. The concentration of heavy metals in the surface sediments of Vellar and Coleroon estuaries and other southeast coastal regions of India were presented in Tables 2 and 3, respectively. The spatial distribution of heavy metals in the study area clearly illustrate that heavy metals are increasing towards coastal region. The concentration range of heavy metals in the Vellar and Coleroon estuaries are Fe (23,328– Table 1 Certified values of MESS-1 compared with our results. Elements (μg·g−1)

MESS 1 (certified value)

Present study

% of recovery

Fe Mn Cr Cu Pb Zn Ni Co

43,600 513 71 25.1 34 191 29.5 10.8

41,758 498.5 69.7 24.2 33.1 187.5 28.4 10.5

95.78 97.17 98.17 96.41 97.35 98.17 96.27 97.22

3

45,520, 31,000–51,200); Mn (652–960, 742–1178); Cr (56–138, 106– 207); Cu (78–157, 96–162); Pb (34–188, 58–180); Zn (78–123, 86– 156); Ni (60–218, 50–156) and Co (18–68, 39–66). The average concentration of heavy metals in the study area is compared with average values of previous study (Ramanathan et al., 1999), it reveals that most of the surface samples of Vellar and Coleroon estuaries were highly contaminated which indicate that the study area was affected by anthropogenic activities in recent decades. The higher concentration of heavy metals found in the study area, where higher mud, high OM and slow flushing (Huang, 1995) helps to precipitation of metals in sediments from overlying water column (Cobelo-Garcia and Prego, 2004). The Vellar and Coleroon rivers flow through densely populated (Salem, Trichy and Chidambaram) areas and carrying fertilizers (both river basins used for agricultural activities), pollutant metals, urban drainages, sewage and industrial effluents (mostly from chemicals, leathers, textiles and metals based industries) that are eventually dumped into the estuarine regions (Ramanathan et al., 1999; Dhanakumar et al., 2013) that led the concentration of heavy metals in the study area. The relatively low concentration of heavy metals especially in estuarine mouth region is mainly due to sediment texture and tidal effects flush the finer particles into deeper region (Jayaprakash et al., 2014). The results of heavy metals in the study area shows Coleroon Estuary was highly contaminated when compared with Vellar Estuary, it is due to high discharge of industrial and municipal wastes carried out by Coleroon River through its course. Recent decades, number of pollution indices have been put forward for quantifying the degree of heavy metals contamination level in the sediments (Caeiro et al., 2005). Various authors have proposed pollution impact scales to convert the results, from low to high intensity. Pollution load index (PLI), contamination factor (CF), enrichment factor (EF) and geo-accumulation index (Igeo) will express the heavy metals contamination in sediments and its possible sources. The classification and calculated values of CF, EF and Igeo were presented in Tables 4 and 5, respectively, and we used continental crustal average by Wedepohl (1995) as background values for calculate these indices. Pollution load index (PLI) was used to find out the mutual contamination effect from different locations by various elements and it was computed as developed by Tomlinson et al. (1980) from the following eq. PLI ¼ n√ ðCF1  CF2  CF3  …CFnÞ where, CF - contamination factor; n - number of metals. PLI value of N 1 is polluted whereas b1 indicates no pollution (Tomlinson et al., 1980). The ranges of PLI in Vellar and Coleroon estuaries were 2.06–4.62 and 2.69–4.89. The PLI values of surface sediments in Vellar and Coleroon were above 1; they illustrate that sediments in the entire study area are strongly polluted by anthropogenic factor or lithogenic influx from the catchment area. Contamination factor (Cif) has been used to determine the contamination status of the heavy metals in sediment and it was calculated according to Hakanson (1980). Ci f ¼ Ci 0–1 =Ci n : where Ci0–1 - mean content of the metal; Cin - reference value for the metal. The average CF values of Fe, Mn and Zn show moderate contamination, Pb and Co show considerable contamination and Cu and Ni show very high contamination in both Vellar and Coleroon estuaries. Cr in Vellar estuary show moderate contamination but in Coleroon Estuary it was considerably contaminated. The values of CF in Vellar and Coleroon estuaries are decreasing in the following order Cu N Ni N Pb N Co N Cr N Zn N Mn N Fe and indicate that both estuaries are highly contaminated by Cu and Ni. Cu and Ni are used as indicators of metal industries (Kumar et al., 2001; Loska et al., 2004); thus these elements are most possibly derived from industrial discharge. Enrichment factor (EF) is a useful tool for evaluating the heavy metal source contributed by anthropogenic activities or by natural sources

Please cite this article as: Nethaji, S., et al., Geochemical assessment of heavy metals pollution in surface sediments of Vellar and Coleroon estuaries, southeast coast of India, Marine Pollution Bulletin (2016), http://dx.doi.org/10.1016/j.marpolbul.2016.11.045

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S. Nethaji et al. / Marine Pollution Bulletin xxx (2016) xxx–xxx

Fig. 2. Sediment texture, CaCO3, OM and heavy metals distribution of Vellar estuarine surface sediments, SE coast of India.

Please cite this article as: Nethaji, S., et al., Geochemical assessment of heavy metals pollution in surface sediments of Vellar and Coleroon estuaries, southeast coast of India, Marine Pollution Bulletin (2016), http://dx.doi.org/10.1016/j.marpolbul.2016.11.045

S. Nethaji et al. / Marine Pollution Bulletin xxx (2016) xxx–xxx

Fig. 2 (continued).

Please cite this article as: Nethaji, S., et al., Geochemical assessment of heavy metals pollution in surface sediments of Vellar and Coleroon estuaries, southeast coast of India, Marine Pollution Bulletin (2016), http://dx.doi.org/10.1016/j.marpolbul.2016.11.045

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S. Nethaji et al. / Marine Pollution Bulletin xxx (2016) xxx–xxx

Fig. 3. Sediment texture, CaCO3, OM and heavy metals distribution of Coleroon estuarine surface sediments, SE coast of India.

Please cite this article as: Nethaji, S., et al., Geochemical assessment of heavy metals pollution in surface sediments of Vellar and Coleroon estuaries, southeast coast of India, Marine Pollution Bulletin (2016), http://dx.doi.org/10.1016/j.marpolbul.2016.11.045

S. Nethaji et al. / Marine Pollution Bulletin xxx (2016) xxx–xxx

Fig. 3 (continued).

Please cite this article as: Nethaji, S., et al., Geochemical assessment of heavy metals pollution in surface sediments of Vellar and Coleroon estuaries, southeast coast of India, Marine Pollution Bulletin (2016), http://dx.doi.org/10.1016/j.marpolbul.2016.11.045

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S. Nethaji et al. / Marine Pollution Bulletin xxx (2016) xxx–xxx

Table 2 Sediment texture, calcium carbonate, organic matter and heavy metals concentration (μg·g−1) in surface sediments of Vellar and Coleroon estuary, SE coast of India. Study area

Vellar

Parameters

Min

Max

Mean

Median

SDa

Min

Max

Mean

Median

SD

Sand Mud CaCO3 OM Fe Mn Cr Cu Pb Zn Ni Co

37.4 17.4 1.0 0.4 23,328 652 56 78 34 78 60 18

82.6 62.6 5.0 1.69 45,520 960 138 157 188 123 218 68

62.43 37.57 2.83 0.84 32,125 756 89 109 82 97 123 37

63.4 36.6 3.0 0.74 32,270 743 90 107 84 96 119 35

10.55 10.55 1.11 0.36 5887 87 21 22.77 45.74 13.35 46.86 14.94

31.6 3.6 1.50 0.2 31,000 742 106 96 58 86 50 39

96.4 68.4 5.00 1.46 51,200 1178 207 162 180 156 156 66

67.92 32.08 2.83 0.75 41,075 977 151 124 100 113 108 50

65 35 2.5 0.7 42,000 1000 146 123 87 108 123 50

17.35 17.35 1.23 0.37 6090 135 34 22.11 37.05 22.92 35.95 7.78

a

Coleroon

SD-standard deviation.

Table 3 Comparison of heavy metals concentration (μg·g−1) in surface sediments of present study along with various south east coastal regions of India. Study area

Published by

Fe

Mn

Cr

Cu

Pb

Zn

Ni

Co

Kallar estuary Korampallam creek Punnakayal estuary Ennore, SE coast Gulf of Mannar East coast estuaries Pichavaram Coleroon estuary Vellar estuary Vellar estuary Coleroon estuary

Magesh et al. (2013) Magesh et al. (2013) Magesh et al. (2013) Muthuraj and Jayaprakash (2008) Jonathan et al. (2004) Hema et al. (2002) Ramanathan et al. (1999) Ramanathan et al. (1999) Ramanathan et al. (1999) Present study Present study

34,125 23,663 28,363 27,200 12,553 28,000 32,482 23,533 25,540 32,125 41,075

356 357 277 373 305 777 941 326 110 756 977

10 26 9 194 177 318 141 49 38 89 151

27 98 31 506 57 NA 43 4.3 11.6 109 124

29 67 28 32 16 11 11 4.6 6 82 100

320 190 231 126 73 125 93 60 97 97 113

34 34 21 38 24 582 62 24 21 123 108

1.4 5.1 3.7 8.1 15 12 35.3 16.6 23 37 50

NA - not available.

(Bastami et al., 2012). This index is calculated based on a normalization (Fe or Al) which moderates the variation produced by heterogeneous sedimentation (Loring, 1991). Natural concentrations of Fe in sediments are more uniform than Al and beyond the influence of humans which justify its use as a normalizer (Daskalakis and O'Connor, 1995). In this study, Fe has been used as a normalizing element because of its enormous availability. The EF (Buat-Menard and Chesselet, 1979) is calculated according to the following formula.

enrichment in Coleroon Estuary and shows moderate to severe enrichment in Vellar Estuary. The abundance of heavy metals enrichment in the study area follows the similar pattern of contamination factor. Another approach to assess the degree of contamination in sediments is geo-accumulation index (Igeo) by comparing the current levels of heavy metal concentrations and the average concentrations of continental crust in the soils and it was defined by Muller (1969) according to the equation.

EF ¼ ðMc =Fec Þ=ðMb =Feb Þ:

Igeo ¼ log2 ðCn=1:5  BnÞ

where, Mc and Fec are the examined metal and iron concentration in the sediments; Mb and Feb. are the background values of examined metal and iron respectively. The EF values ranges from minor enrichment to severe enrichment. Mn and Zn show minor enrichment; Pb show moderate enrichment and Cu show moderate to severe enrichment in both estuaries. Cr and Co shows minor enrichment in Vellar Estuary but in Coleroon Estuary they show moderate enrichment. Ni shows moderate

where, Cn – measured concentration of metal; Bn – background value of the same metal. Concentrations of geochemical background are multiplied each time by the factor 1.5 is used to reduce possible variations in background values for a given metal in the environment, as well as very small anthropogenic influences (Huu et al., 2010). The geoaccumulation index of Fe shows unpolluted; Zn shows unpolluted to moderately polluted; Pb shows moderately polluted and Cu shows moderate to strong pollution in both estuaries. Igeo of Mn in Vellar Estuary was unpolluted but in Coleroon Estuary it was unpolluted to moderately polluted; Cr and Co shows unpolluted to moderately polluted in Vellar and moderate pollution in Coleroon Estuary. Igeo of Ni shows moderate pollution in Coleroon estuary but in Vellar Estuary it was moderate to strong pollution. The average abundance of Igeo values also following the similar arrangement of contamination and enrichment factor. Pearson correlation matrix was used for the present study to determine the inter-elemental relationship between sediment texture, organic matter and heavy metals. In an estuarine environment it is very important to know the behavior and source of heavy metals. The correlation coefficients of Vellar and Coleroon estuaries (Table 6) show that all the heavy metals are significantly positive correlation with mud, OM and each other, except sand and CaCO3. The strong positive

Table 4 Classification of contamination factor, enrichment factor, and geo-accumulation index for heavy metals in sediments. CF value

Contamination EF value

b1 Low ≥1 b 3 Moderate

b1 1–3

≥3 b 6 Considerable ≥6 Very high

3–5 5–10

Enrichment

Igeo Quality of value sediments

No Minor

b0 0–1

Moderate Moderate to severe 10–25 Severe 25–50 Very severe N50 Extremely severe

1–2 2–3

Unpolluted Unpolluted to moderate Moderately polluted Moderate to strong

3–4 4–5 N5

Strongly polluted Strong to extreme Extremely polluted

Please cite this article as: Nethaji, S., et al., Geochemical assessment of heavy metals pollution in surface sediments of Vellar and Coleroon estuaries, southeast coast of India, Marine Pollution Bulletin (2016), http://dx.doi.org/10.1016/j.marpolbul.2016.11.045

S. Nethaji et al. / Marine Pollution Bulletin xxx (2016) xxx–xxx

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Table 5 Pollution load index, contamination factor, enrichment factor and geo-accumulation index for heavy metals in surface sediments of Vellar and Coleroon estuary, SE coast of India. Indices

Vellar

Coleroon

Min

Max

Mean

Median

SD

Min

Max

Mean

Median

SD

Pollution load index 2.06

4.62

2.87

2.7

0.71

2.69

4.89

3.6

3.44

0.7

Contamination factor Fe 0.76 Mn 1.24 Cr 1.60 Cu 5.45 Pb 2.00 Zn 1.50 Ni 3.23 Co 1.58

1.47 1.82 3.94 10.98 11.06 2.37 11.72 5.87

1.04 1.43 2.55 7.63 4.82 1.87 6.59 3.17

1.04 1.41 2.57 7.52 4.94 1.86 6.42 3.00

0.19 0.16 0.60 1.59 2.69 0.26 2.52 1.29

1.00 1.41 3.03 6.71 3.41 1.65 2.69 3.36

1.66 2.24 5.91 11.33 10.59 3.00 10.00 5.73

1.33 1.85 4.32 8.66 5.89 2.17 6.08 4.34

1.36 1.90 4.17 8.60 5.15 2.08 6.59 4.30

0.20 0.26 0.96 1.55 2.18 0.44 2.33 0.67

Enrichment factor Mn 1.22 Cr 1.45 Cu 5.79 Pb 2.06 Zn 1.46 Ni 3.30 Co 1.91

1.81 3.14 9.36 7.50 2.55 8.37 4.75

1.40 2.46 7.39 4.41 1.82 6.32 2.97

1.33 2.49 7.34 4.52 1.79 7.04 2.90

0.18 0.41 1.12 1.73 0.28 1.96 0.81

1.18 2.16 5.33 2.98 1.18 2.13 2.82

1.73 4.07 7.39 7.47 2.12 6.23 4.13

1.40 3.26 6.52 4.38 1.65 4.47 3.28

1.38 3.41 6.65 4.16 1.62 4.67 3.28

0.15 0.60 0.69 1.26 0.31 1.29 0.37

Geo-accumulation index Fe −0.99 Mn −0.28 Cr 0.09 Cu 1.86 Pb 0.42 Zn 0.00 Ni 1.10 Co 0.07

−0.03 0.28 1.39 2.87 2.88 0.66 2.97 1.97

−0.55 −0.07 0.73 2.32 1.48 0.30 2.04 0.98

−0.52 −0.09 0.78 2.33 1.70 0.31 2.10 1.00

0.26 0.16 0.34 0.29 0.82 0.20 0.57 0.56

−0.58 −0.09 1.01 2.16 1.19 0.14 0.84 1.16

0.14 0.58 1.98 2.92 2.82 1.00 2.74 1.93

−0.19 0.29 1.49 2.51 1.89 0.51 1.90 1.52

−0.14 0.34 1.48 2.52 1.78 0.47 2.13 1.52

0.22 0.21 0.32 0.25 0.49 0.28 0.63 0.22

correlation between sand and carbonate (r2 = 0.86, 0.85) in both estuaries is due to calcareous sand distribution with broken shell materials in the coastal region. Sand shows negative correlation with all other parameters, which indicates that coarser fraction does not hold any heavy metals because these metals can be easily released by ion-exchange

processes due to weak bound (Morillo et al., 2004). Fe and Mn have strong positive correlation with other metals suggesting that they are attached to Fe\\Mn oxyhydroxides. The significant positive correlation of heavy metals with mud and organic matter illustrate that fine particles play an important role in adsorption and distribution of heavy

Table 6 Correlation coefficient matrix (R2) of sediment texture, CaCO3, and OM with heavy metals in surface sediments of Vellar and Coleroon estuary, SE coast of India. Vellar (n = 12)

Sand

Mud

CaCO3

OM

Fe

Mn

Cr

Cu

Pb

Zn

Ni

Co

Sand Mud CaCO3 OM Fe Mn Cr Cu Pb Zn Ni Co

1 −1a 0.863a −0.896a −0.877a −0.927a −0.868a −0.762a −0.816a −0.745a −0.647b −0.826a

1 −0.863a 0.896a 0.877a 0.927a 0.868a 0.762a 0.816a 0.745a 0.647b 0.826a

1 −0.854a −0.699b −0.793a −0.741a −0.894a −0.600b −0.608b −0.760a −0.875a

1 0.839a 0.885a 0.851a 0.890a 0.776a 0.781a 0.858a 0.929a

1 0.807a 0.723a 0.718a 0.895a 0.692b 0.574 0.817a

1 0.821a 0.772a 0.838a 0.813a 0.685b 0.822a

1 0.733a 0.653b 0.530 0.743a 0.716a

1 0.626b 0.623b 0.900a 0.929a

1 0.791a 0.440 0.802a

1 0.473 0.744a

1 0.776a

1

Coleroon (n = 12)

Sand

Mud

CaCO3

OM

Fe

Mn

Cr

Cu

Pb

Zn

Ni

Co

Sand Mud CaCO3 OM Fe Mn Cr Cu Pb Zn Ni Co

1 −1a 0.859a −0.887a −0.881a −0.840a −0.728a −0.828a −0.748a −0.573 −0.659b −0.683b

1 −0.859a 0.887a 0.881a 0.840a 0.728a 0.828a 0.748a 0.573 0.659b 0.683b

1 −0.763a −0.822a −0.835a −0.553 −0.746a −0.427 −0.270 −0.719a −0.657b

1 0.840a 0.923a 0.797a 0.855a 0.803a 0.788a 0.725a 0.791a

1 0.776a 0.596b 0.828a 0.649b 0.530 0.742a 0.772a

1 0.756a 0.756a 0.679b 0.624b 0.624b 0.611b

1 0.790a 0.836a 0.810a 0.385 0.557

1 0.684b 0.656b 0.586b 0.860a

1 0.918a 0.476 0.520

1 0.433 0.545

1 0.713a

1

a b

Correlation is significant at 0.01 level. Correlation is significant at 0.05 level (2-tailed).

Please cite this article as: Nethaji, S., et al., Geochemical assessment of heavy metals pollution in surface sediments of Vellar and Coleroon estuaries, southeast coast of India, Marine Pollution Bulletin (2016), http://dx.doi.org/10.1016/j.marpolbul.2016.11.045

10

S. Nethaji et al. / Marine Pollution Bulletin xxx (2016) xxx–xxx

metals in sediments (Jonathan et al., 2004). Significant correlation between heavy metals in both estuaries shows similar source of pollution from the industrial wastes carried by the rivers (Muthuraj and Jayaprakash, 2008). Factor analysis provides several positive features that allow interpretation of the data set more scientifically. Factor analysis was carried out to understand the variability of heavy metals, sediment texture, CaCO3 and organic matter (Table 7). Based on the factor loading, sand and carbonate have negative factor loading in all factors of both estuaries which illustrate that sand and carbonates are not responsible for heavy metals accumulation. The extracted factors of Vellar Estuary show high positive loadings of mud, OM, Cu, Ni and Co in factor 1 indicating that they are associated with fine particles. Mud, OM, Fe, Mn, Pb and Zn show high positive loading in factor 2 suggest that Fe\\Mn oxyhydroxides absorbed these metals (Jayaprakash et al., 2014). The strong positive loading of Fe, Mn and Cr in factor 3 is possibly due to lithogenic input from adjacent landmass. The factors of Coleroon Estuary show strong positive loadings of mud, Fe, Mn and Cu in factor 1, whereas OM, Cr, Pb and Zn show high positive loading in factor 2; Ni and Co show in factor 3. Thus, factors of Vellar and Coleroon estuaries reveal enrichment of heavy metals in the sediments mainly due to Fe\\Mn oxyhydroxides, organic matter and fine particles. Venkatramanan et al. (2015) also reported that Fe\\Mn oxyhydroxides play an important role in scavenging heavy metals like Zn, Pb, Cu, and Ni. These metals, enriched in sediments from various anthropogenic effluents and discharged by Vellar and Coleroon rivers are then precipitated and adsorbed by finer particles. Geochemical assessment of surface sediments in Vellar and Coleroon estuaries reveals Fe\\Mn oxyhydroxides, mud and organic matter have led the accumulation of heavy metals. The average concentration of heavy metals in the study area is higher than continental crustal average. PLI values clearly illustrate that all the sediments are polluted in both estuaries. The calculated contamination factor, enrichment factor and geo-accumulation index were show similar pattern of decreasing order Cu N Ni N Pb N Co N Cr N Zn N Mn in both estuaries. It illustrates that the sediments are highly contaminated by Cu, Ni and Pb. The results of correlation coefficients and factor analysis clearly show the relationship between heavy metals, sediment texture and organic matter. The sources of heavy metals in the estuarine sediments are mainly from municipal wastes, industrial effluents and agricultural activities. The industrial wastes such as chemicals, leathers and metals carried out by both rivers through their courses have damaged the Vellar and Coleroon estuarine ecosystems. Further studies on heavy metals in estuarine environments are required for better understanding and effective environmental management of the estuarine ecosystem.

Table 7 Results of factor analysis in surface sediments of Vellar and Coleroon estuary, SE coast of India. Parameters

Sand Mud CaCO3 OM Fe Mn Cr Cu Pb Zn Ni Co

Vellar

Coleroon

Factor 1

Factor 2

Factor 3

Factor 1

Factor 2

Factor 3

−0.409 0.707 −0.719 0.674 0.325 0.442 0.485 0.859 0.194 0.317 0.901 0.701

−0.555 0.555 −0.358 0.537 0.671 0.623 0.238 0.381 0.836 0.869 0.138 0.607

−0.707 0.409 −0.462 0.468 0.548 0.569 0.799 0.287 0.430 0.167 0.314 0.294

−0.798 0.798 −0.881 0.577 0.660 0.748 0.458 0.532 0.326 0.088 0.400 0.309

−0.434 0.434 −0.074 0.610 0.321 0.475 0.813 0.524 0.878 0.941 0.143 0.336

−0.351 0.351 −0.430 0.497 0.582 0.284 0.124 0.532 0.206 0.287 0.797 0.829

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Please cite this article as: Nethaji, S., et al., Geochemical assessment of heavy metals pollution in surface sediments of Vellar and Coleroon estuaries, southeast coast of India, Marine Pollution Bulletin (2016), http://dx.doi.org/10.1016/j.marpolbul.2016.11.045