Distribution and geochemical speciation of sediment bound heavy metals in the specific zones of central Kerala, India

Abstract

Heavy metal pollution of aquatic environments in fishing regions is of considerable global concern due to its potential to cause serious harm to aquatic ecosystems and human health. This study assessed spatial distribution and chemical fraction of heavy metal contamination (Cd, Pb, Cu, Zn, Mn, Co, Ni and Fe) of surface sediments in the major fishing zones of Central Kerala, South west coast of India. The heavy metal content varied from 1.05 to 2.29 mg/kg for Cd, 28.59 to 73.90 mg/kg for Pb, 15.60 to 55.41 mg/kg for Cu, 22.20 to 99.26 mg/kg for Zn, 11.88 to 137.89 mg/kg for Mn, 17.28 to 30.46 mg/kg for Co, 19.67 to 70.23 mg/kg for Ni and 715.31 to 1145.85 mg/kg for Fe, respectively. The present study highlights the geochemical speciation and pollution status of heavy metals in the sediments of Central Kerala. Sequential extraction results of metal revealed that Pb was predominantly associated with the exchangeable fraction and concurrently found that residual binding fraction was the most important phase for binding Fe and Ni. Cu includes the largest proportion of the carbonate fraction, while Cd was noted the most prominent metal in the Fe-Mn oxide fraction and exchangeable fraction. The adopted pollution assessment methodology showed that the system is enriched with heavy metal and that Cd be the metals of prime concern.