Journal of Environmental Science, Computer Science and. Engineering & Technology. An International Peer Review E-3 Journal of Sciences and Technology.
J ECET; Dec. 2014- Feb. 2015; Sec. A Vol.4.No.1, 0000-0000.
E-ISSN: 2278–179X
Journal of Environmental Science, Computer Science and Engineering & Technology An International Peer Review E-3 Journal of Sciences and Technology
Available online atwww.jecet.org Section A: Environmental Science Research Article
Heavy metal accumulation in a mangrove associate species Ipomoea pes-caprae in and around the World Heritage Site of Indian Sundarbans Abhijit Mitra1 , Bulti Nayak2* , Prosenjit Pramanick1 , Madhumita Roy2 , Shankhadeep Chakraborty1 , Kakoli Banerjee 3 , Gahul Amin4 and Sufia Zaman1 1
Department of Oceanography, Techno India University, Salt Lake Campus, Kolkata 700091, India
2*
Department of Biotechnology, Techno India University, Salt Lake Campus, Kolkata 700091, India 3
School of Biodiversity and Conservation of Natural Resources, Central University of Orissa, Koraput 4
Department of Physics, Chanchal College, Malda-732123, India
Received: 07 November 2014; Revised: 17 November 2014; Accepted: 27 November 2014
Abstract: The accumulation of Fe, Zn, Cu and Pb was analyzed in an estuarine trailing herb Ipomoea pes-caprae from three locations in Indian Sundarbans during September 2014. The contamination history of the area provides substantial evidence that metal accumulation in the species is influenced from multiple sources (like industrial discharge, fish landing related activities, antifouling paints used for conditioning fishing vessels and trawlers, shrimp farms etc.). Metals in the mangrove associate species accumulated as per the order Fe > Zn > Cu > Pb. Significant variation was observed between the metal levels in the vegetative parts of the species (p < 0.01). The stem accumulated maximum metal followed by leaf and root irrespective of sampling stations. Keywords: Heavy metals, bioaccumulation, Ipomoea pes-caprae, spatial variation. JECET; December 2014-February 2015; Sec. A, Vol.4.No.1, 0000-0000.
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INTRODUCTION Considering the biodiversity of flora and fauna, the Indian sub-continent is considered as one of the richest eco-regions of the world1, 2 . A thorough evaluation on the reports of biodiversity census indicates that about 6% of the global diversity of flowering plants occurs in India alone 3 . Many coastal plants are yet untapped and unidentified, which have immense ecological and medicinal value. The Sundarban delta ecosystem at the apex of Bay of Bengal sustains some 34 true mangrove species and a number of mangrove associates. Ipomoea pes-caprae commonly known as goat’s foot is a trailing herb found abundantly in the sand dominated intertidal mudflat of Indian Sundarbans. The herb has long stems, sometimes twining and reaching upto 30 m length. The leaves are simple, ovate, quadrangular, rounded, measuring 2.5 cm by 10 cm with slender petioles that can be as long as 17 cm (Figure-1).
Figure-1: Ipomoea pes-caprae - a trailing herb found abundantly in Indian Sundarbans The study site is exposed to pollution from the highly urbanized city of Kolkata, Howrah and the newly developed Haldia port-cum-industrial complex4-7 . These heavy metals are absorbed by the endemic vegetation of the region8 . However scientific data on the bioaccumulation of heavy metals in the coastal vegetation particularly mangrove associate species are limited. In this study we have investigated bioconcentrations of iron, zinc, copper and lead in the vegetative parts of I. pes-caprae collected from three different locations of Indian Sundarbans during September, 2014. MATERIALS AND METHODS Station selection and sampling: Three stations (Figure-2) were selected in and around the central part of Indian Sundarbans namely Canning – Stn.1 (22°18΄37"N; 88°40΄36"E), Chhotomollakhali Island – Stn.2 (22º10'21.74''N; 88º53'55.18''E) and Bali Island – Stn.3 (22º04'35.17''N; 88º44'55.70''E). The species was collected at ebb within 500 meter coastal stretch at three selected stations. The collected samples were brought to laboratory, washed and dried with tissue paper and stored at -200 C for further analysis after segregating the leaf, stem and root. JECET; December 2014-February 2015; Sec. A, Vol.4.No.1, 0000-0000.
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Canning Stn-1 (22°18'37'' N, 88°40'36'' E) Chotomollakhali Stn-2 (22°10'21.74'' N, 88°53'55.18'' E) Bali Stn-3 (22°04'35.17'' N, 88°44'55.7'' E)
Figure-2: Map of Indian Sundarbans showing the sampling stations Analysis of tissue Fe, Zn, Cu and Pb: 20 gm leaf, stem and root samples of the collected species were oven dried separately at 105o C overnight to a constant weight. 1 gm of dried sample was digested with a mixture of 10 ml nitric acid and perchloric acid (3:1) till a clear solution was obtained. The resulting solution was made up to a constant volume with 0.05N nitric acid. Each sample was analysed for Fe, Zn, Cu and Pb against standard concentration of each metal on a Perkin Elmer Atomic Absorption Spectrophotometer (Model 3030) equipped with a HGA – 500 graphite furnace atomizer and a deuterium background corrector. Blank correction was done to bring accuracy to the results. Data analysis: SPSS 16.0 was used for ANOVA to determine the variations of heavy metal level between the vegetative parts (root, stem and leaf) and also between the sampling stations. RESULTS The lowest and highest concentrations of heavy metals in the vegetative parts of the selected species were detected in the samples collected from Bali Island and Canning respectively. Fe ranges from 998.67 ppm dry weight to 1034.17 ppm dry weight in roots, 1859.30 ppm dry weight to 2657.43 ppm JECET; December 2014-February 2015; Sec. A, Vol.4.No.1, 0000-0000.
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dry weight in stems and 1256.44 ppm dry weight to 1609.36 ppm dry weight in leaves. Zn ranges from 219.65 ppm dry weight to 294.09 ppm dry weight in roots, 291.84 ppm dry weight to 431.66 ppm dry weight in stems, 275.42 ppm dry weight in leaves to 399.16 ppm dry weight in leaves. Cu ranges from 31.02 ppm dry weight to 42.98 ppm dry weight in roots, 50.54 ppm dry weight to 57.10 ppm dry weight in stems, 43.55 ppm dry weight to 49.60 ppm dry weight in leaves. In all the three stations, Pb is below detectable label (BDL) in the I. pes-caprae root and leaf, whereas, in stem the value of Pb ranges from BDL (at Bali and Chotomollakhali Islands) to 2.39 ppm dry weight (at Canning) (Figures 3, 4, 5 and 6 ).
Figure-3: Fe (in ppm dry wt.) in root, stem and leaf of I. pes-caprae
Figure-4: Zn (in ppm dry wt) in root, stem and leaf of I. pes-caprae JECET; December 2014-February 2015; Sec. A, Vol.4.No.1, 0000-0000.
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Figure-5: Cu (in ppm dry wt.) in root, stem and leaf of I. pes-caprae
Figure-6: Pb (in ppm dry wt) in root, stem and leaf of I. pes-caprae ANOVA computed with the data set generates two interesting findings: (1) Except Pb, accumulation of Fe, Zn and Cu exhibited significant variations between the selected vegetative parts (root, stem and leaf) of the species. (Table-1). (2) Zn and Cu exhibited pronounced spatial variations unlike Fe and Pb. (Table-1).
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Table-1: ANOVA of heavy metal concentrations between selected stations and vegetative parts of Ipomoea pes-caprae Variables Fe Between stations Between vegetative parts Zn Between stations Between vegetative parts Cu Between stations Between vegetative parts Pb Between stations Between vegetative parts
Fcal
Fcrit
2.69 20.31
6.94 6.94
35.50 29.27
6.94 6.94
14.82 62.68
6.94 6.94
1 1
6.94 6.94
DISCUSSION Heavy metals are readily mobilized by human activities like mining and discarding industrial waste materials to the aquatic system9, 10 . Heavy metals accumulate faster in coastal vegetation due to their close proximities to developed areas and metal contamination range from industrial waste to garbage dump11 . Fe in coastal ecosystem originates from land erosion, floating old stranding rusty barges, rusty jetties etc 5 . However, Fe is not an issue of concern, but Zn, Cu and Pb are of greatest ecotoxicological concern. Researchers observed that Zn, Cu and Pb are primarily sourced from antifouling paints (used for conditioning fishing vessels and trawlers), apart from industrial discharges12 . Pb accumulation in the coastal ecosystem also occurs from the atmosphere 13 . Concentration of all the metals exhibited a pronounced variation in vegetative parts, the value been highest in stem followed by leaf and root. The present result, however, deviates from the work of several other researchers 14 who observed the accumulation order of Zn in I. pes-caprae as stem > root > leaf. For Cu, the order was leaf > root > stem and in case of Pb, the order was root > stem > leaf. There was also a high variability in metal concentrations between different stations (Table 1). The metals accumulated in the herb as per the order Fe > Zn > Cu > Pb. This order is a reflection of the metal levels in the ambient media. Metals in the present study site are probably derived from point sources surrounding the site preferably the industries from the upstream and downstream areas 6, 12 . In addition, antifouling paints used for conditioning fishing vessels and trawlers and floating old rusty stranded barges are also the sources of heavy metals in the present area 6 . Different metal accumulation pattern by I. pes-caprae between the sampling sites are attributable to a spatial variability of anthropogenic metal input in the study site and digenetic behaviour of the intertidal sediment system. However, the second issue has not been evaluated in details. Further long term investigation needs to be conducted to evaluate this mangrove associate species as potential sink and indicator of heavy metals. REFERENCES 1. G. Agoramoorthy, M.J. Hsu, Biodiversity surveys are crucial for India, Current Science, 2002, 82 (3), 244. 2. G. Agoramoorthy, M.J. Hsu, Borneo’s proboscis monkey—a study of its diet of mineral and phytochemical concentrations, Current Science, 2005, 89, 454-457. JECET; December 2014-February 2015; Sec. A, Vol.4.No.1, 0000-0000.
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3. BSI, Flora and Vegetation of India, An Outline, Botanical Survey of India Publication, Howrah, 1983. 4. A. Mitra, A. Choudhury, Trace metals in macrobenthic molluscs of the Hooghly estuary, India. Marine Pollution Bulletin, UK, 1993, 26 (9), 521-522. 5. A. Mitra, Status of coastal pollution in West Bengal with special reference to heavy metals. Journal of Indian Ocean Studies, 1998, 5 (2), 135 –138. 6. A. Mitra, R. Choudhury, K. Banerjee, Concentrations of some heavy metals in commercially important finfish and shellfish of the River Ganga. Environmental Monitoring and Assessment, 2012, 184, 2219 – 223. (SPRINGER DOI 10.1007/s10661-011-2111-x). 7. A. Mitra, S. Zaman, S.B. Bhattacharyya, Heavy metal pollution in the lower Gangetic ecosystem. In: Water Insecurity: A Social Dilemma (Edited by Md. Anwarul Abedin, Umma Habiba and Rajib Shaw) published by Emerald Group Publishing Limited (ISBN: 9781781908822), 2013. 8. S. Chakraborty, S. Trivedi, P. Fazli, S. Zaman, A. Mitra, Avicenia alba: an indicator of heavy metal pollution in Indian Sundarban estuaries. Journal of Environmental Science, Computer Science and Engineering & Technology, 2014, 3(4), 1796-1807. 9. G. Agoramoorthy, Computer "recycling" builds garbage dump overseas', Nature, 2006, 441, 25. 10. M.J. Hsu, K. Selvaraj, G. Agoramoorthy, Taiwan's industrial heavy metal pollution threatens terrestrial biota. Environmental Pollution, 2006, 143 (2), 327-334. 11. J. Stark, Heavy metal pollution and macrobenthic assemblages in soft sediments in two Sydney estuaries. Australia Marine and Freshwater Research, 1998, 49, 533. 12. A. Mitra, K. Banerjee, S. Sinha, Shrimp tissue quality in the lower Gangetic delta at the apex of Bay of Bengal. Toxicological & Environmental Chemistry, 2011, 93 (3), 565 – 574. 13. B. Braune, D. Muir, B. DeMarch, M. Gamberg, K. Poole, R. Currie, et al, Spatial and temporal trends of contaminants in Canadian Arctic freshwater and terrestrial ecosystems: a review. Science of the Total Environment, 1999, 230, 145. 14. U.U. Umoh, S.F. Dan, Okon, E.E. Duke, Commelina Bengalensis and Ipomoea pescaprae as indication of Heavy Metal contamination along Mobil Termination Operation Base, Niger Delta, Nigeria. J.ournal of Academia and Industrial Research, 2014, 3 (5), 225-228.
* Corresponding Author: Bulti Nayak Department of Biotechnology, Techno India University, Salt Lake Campus, Kolkata 700091, India
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