Baseline Assessment of trace metal contamination level and toxicity in sediments from coastal regions of West Bengal, eastern part of India Blanca Antizar-Ladislao a, ⁎, Priyanka Mondal b , Soumita Mitra b , Santosh Kumar Sarkar b a Emerald Energy Consultancy Ltd., England LN7 6GN, United Kingdom b Department of Marine Science, University of Calcutta, 35 Ballygunge Circular Road, Calcutta 700019, India abstract article info Article history: Received 24 February 2015 Received in revised form 2 November 2015 Accepted 6 November 2015 Available online xxxx The work investigated concentration of trace metals in surface sediments (0–10 cm; b 63 μm grain size) from 15 sampling sites of diverse environmental stresses covering Hugli River Estuary (HRE) and Sundarban Mangrove Wetland (SMW), eastern coastal part of India. The trace metal concentrations in sediments exhibited an overall decreasing trend as follows: Cr (21.2–60.9) N Cu (11.60–102.47) N Ni (19.10–52.60) N Pb (7.09–183.88) N As (4.41–11.46) N Cd (0.02–4.4) N Ag (0.02–0.87). Both the geo-accumulation index (I geo ) and contamination factor (CF) values revealed significant pollution by Ag, Cd and Pb at Nurpur of HRE. Potential Ecological Risk Index (RI) (61.21 ± 112.40) showed wide range of variations from low (19.76) to serious (463.20) ecological risk. A positive significant correlation was found between metals and organic carbon in sediments. The ecological risk associated with the trace metals in sediment was considered on the consensus based Sediment Quality Guidelines (SQGs). The work suggests that the trace metals present in sediments posed adverse effects on the sediment-dwelling organisms. © 2015 Published by Elsevier Ltd. Keywords: Trace metals Ecotoxicology Sediment quality Ecological risk index Hugli River Estuary Indian Sundarban Contamination of aquatic environment by trace metals has been intensively studied in recent years, due to the fact that metals are persis- tent, toxic, tend to bioaccumulate, and that they induce a risk for humans and ecosystems (Liang et al., 2011; Lenoble et al., 2013). The main reason for this is the increasing complex mixtures of chemicals discharged to the coastal zone from non-point sources, especially in developing countries. Coastal areas are usually urbanized and industri- alized, and are therefore subjected to the release of trace metals some- times in significant amounts (Diop et al., 2012; Memet and Bülent, 2012; Bodin et al., 2013). Indeed, sediments are ecologically important components of the aquatic habitat and are also a reservoir of contami- nants, which play a significant role in maintaining the trophic status of any water body. The measurements of pollutants in the water column only are not conclusive due to water discharge fluctuations and low res- idence time. The study of sediment plays an important role as they have a long residence time. Therefore, the analysis of estuarine and coastal sediments is a useful method to study the metal pollution in these areas (Diop et al. 2015). The pollution status of marine sediments has often been used as an important criterion to evaluate the condition of coastal environment and to understand the possible environmental changes caused by anthropogenic activities (Chapman et al., 2013). Due to persistence, bioaccumulation and toxicity of trace metal pollu- tion, investigations of coastal area have been carried out in many rapidly developing regions around Asia to evaluate metal enrichment and pol- lution status (Zhang and Gao, 2015; Gao and Li, 2012; Hosono et al., 2010; Hu et al., 2013; Jiang et al., 2014; Qiao et al., 2013; Tanner et al., 2000; Xia et al., 2011). The main aim of this study was to reveal the spa- tial distribution of the trace metals in surface sediments, to evaluate the potential ecological risk and toxicity of sediment-bound trace elements considering ecological risk index and sediment quality guidelines (SQGs) and to assess the trace metal contamination level by using sed- iment quality parameters. The Hugli-Matla estuarine complex, which supports the world's largest magnificent mangrove block, the Sundarban (area 9620 km 2 ), is a typical and unique ecosystem of the Indian subcontinent and has been recognized as a UNESCO World Heritage Site. This is one of the most sensitive but complex ecosystems in the world and suffers from environmental degradation due to rapid human settlement, tourism and port activities, operation of excessive number of mechanized boats, deforestation, and increasing agricultural and aquaculture prac- tices. The ongoing degradation is also related to huge siltation, flooding, storm runoff, atmospheric deposition, and other environmental stresses resulting in changes in water quality, depletion of fishery resources, blocking of river mouth and inlets, and overall loss of biodiversity (Bhattacharya and Sarkar, 2003; Sarkar et al., 2007). Recent studies on the pollution status of the Hugli River and adjacent Sundarban wetland have revealed the presence of both inorganic and organic pollutants in sediments which have changed the estuary's geochemistry and affected the coastal environment (Watts et al., 2013; Sarkar et al., 2012; Antizar-Ladislao et al., 2011). Marine Pollution Bulletin xxx (2015) xxx–xxx ⁎ Corresponding author. E-mail address: b_antizar@hotmail.com (B. Antizar-Ladislao). MPB-07307; No of Pages 9 http://dx.doi.org/10.1016/j.marpolbul.2015.11.014 0025-326X/© 2015 Published by Elsevier Ltd. Contents lists available at ScienceDirect Marine Pollution Bulletin journal homepage: www.elsevier.com/locate/marpolbul Please cite this article as: Antizar-Ladislao, B., et al., Assessment of trace metal contamination level and toxicity in sediments from coastal regions of West Bengal, eastern part of India, Marine Pollution Bulletin (2015), http://dx.doi.org/10.1016/j.marpolbul.2015.11.014