ORIGINAL ARTICLE Assessment of heavy metal contamination in the surface sediments in the mangrove ecosystem of Gulf of Kachchh, West Coast of India Goutam Kumar • Manoj Kumar • A. L. Ramanathan Received: 22 May 2014 / Accepted: 11 January 2015 Ó Springer-Verlag Berlin Heidelberg 2015 Abstract This study was an attempt to understand the role of biogeochemical processes in controlling the heavy metal distribution in the mangroves and to assess heavy metal pollution load (viz. Cr, Fe, Mn, Co, Ni, Cu, Zn, Cd, and Pb) in the Gulf of Kachchh, India. Vari- ous biogeochemical processes and anthropogenic factors were playing an important role in altering the concentration of heavy metals in the sediments. A significant correlation of Mn, Fe and Pb with Zn implies the role of diffused anthropogenic activities. The organic carbon content (1.47–3.25 %) and clay content (0.1–2.5 %) seem to play a significant role in the metal concentration. Factor analysis suggested two different processes, Factor I strongly indi- cating anthropogenic activities and Factor II indicating the combination of natural, marine in situ reduction processes (biogeochemical) with partial anthropogenic influence. The enrichment factor (EF) and Geochemical Index (I geo ) of Cu were higher at Old Bedi Port (S5), whereas both these values were higher for Cu as well as Cd at Jam- Salaya (S8). I geo values indicate that sediments around the estuarine mouths were polluted with heavy metals as compared to other locations. Except Chodeshwar (S9), PLI value [ 1 was reported in almost all the locations, with a slightly higher value reported at Narara (S7); (1.57) and New Bedi Port (S4); (1.56). The findings of this study would help in formulating guidelines for controlling the pollution and suggest the ways by which the mangroves of the Gulf of Kachchh could be revitalized. Keywords Gulf of Kachchh  Sediment  Heavy metals  Pollution Load Index (PLI)  Average Shale Values (ASV)  All Composite Locations (ACL) Introduction Coastal and marine ecosystems are potentially at risk due to a high concentration of heavy metals in the sediments. Salinity (Coakley et al. 1993), freshwater discharge (Forstner and Whittmann 1981; Chakraborty et al. 2012), flow rates (Schoellhamer 1995) and geomorphological setup are important factors which affect the concentration of heavy metals in the sediments within estuaries. Sedi- ments made up of different grain size such as clay, silt and sand, and other geochemical phases like organic material, oxides of iron and manganese, carbonates and sulphide complexes, act as potential binding sites for metals which enter in an estuarine system (Jonathan et al. 2004; Kumar et al. 2013a, b). Sediments have the ability to accumulate and assimilate heavy metals even from low concentrations in the overlying water column (Tam and Wong 2000; El Nemr et al. 2007). Seawater quality could be directly affected by the metal contamination of surface sediments. This may be potentially harmful to the sensitive lowest levels of the food chain and consequently pose a risk to human health. Complex processes of exchange of materials determine the distribution of metals within the aquatic environments. These processes are influenced by various anthropogenic activities and by natural processes like coastal and seafloor erosion, and inputs from riverine, biological activities, water drainage, industrial effluents and air-borne matter precipitation (Leivouri 1998; Ip et al. 2007). The toxicity, resistance to degradation and tendency to bio-accumulate make heavy metals ecologically critical G. Kumar  M. Kumar  A. L. Ramanathan (&) School of Environmental Sciences, Jawaharlal Nehru University, New Delhi 110067, India e-mail: alrjnu@gmail.com 123 Environ Earth Sci DOI 10.1007/s12665-015-4062-y