Metal bioavailability in sediments and bioaccumulation in edible fishes from Caranzalem beach, Goa, India

Abstract

The extent of metal enrichment in sediment and its subsequent bioaccumulation in locally consumed fishes in the coastal region of Caranzalem, Goa, India, remains un-investigated. Therefore, the surface sediment samples from the intertidal region of the Caranzalem Beach were analysed to assess the metal bioavailability. Additionally, metals in the muscles, gills, liver and kidney of widely consumed edible fishes caught through the rampon fishing technique were quantified to evaluate the metal toxicity implications to fishes and humans. Bioavailable Mn, Zn, Cu, Co and Ni were significantly (greater than 35 percent) bound to sediment. The bioavailability of Zn, Cu, Co and Ni was governed by Fe-Mn oxides/hydroxides and organic matter/sulphide fractions, while Mn was primarily adsorbed onto the carbonate fraction. The Risk Assessment Code (RAC) indicated medium to very high risk of Mn, Zn, Cu and Ni, while the Screening Quick Reference Table (SQUIRT) highlighted potential toxicity of Mn to biota. The majority of collected fish species had the highest accumulation of metals in the kidney, a pattern further corroborated by the modified Biota Sediment Accumulation Factor (mBSAF). This higher renal accumulation of metals compared to liver, gills and muscles was attributed to its physiological functions such as filtration, excretion and ion regulation. The concentration of Fe, Mn, Zn and Cu in muscles of eleven commonly consumed fish species including S. longiceps, R. kanagurta and others exceeded the standard permissible limit. Furthermore, Target Hazard Quotient (THQ) greater than 1 for Fe and Hazard Index (HI) greater than 1 for all species suggested a possibility of metal toxicity to humans upon consumption.