Assessment of heavy metal contamination in the surface sediments in the mangrove ecosystem of Gulf of Kachchh, West Coast of India

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. Various 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 indicating 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.