Chemistry and biochemistry of magnesium

The present study examined the levels of accumulation pattern of seven heavy metals such as essential metals (Iron (Fe), Magnesium (Mg), Zinc (Zn), Copper (Cu)) and non-essential metals (Cadmium (Cd), Lead (Pb), Mercury (Hg)) in 13 tropical marine fishes collected from three major fish landings viz., Chennai, Nagapattinam and Tuticorin, Tamil Nadu. The overall accumulation pattern of all metals was found to be significant (P<0.05) between different species and three different landing centres. The orders of heavy metals in descending order were Mg > Fe > Zn > Cu > Hg > Pb > Cd in Chennai, followed by Mg > Fe > Zn > Hg > Pb > Cu > Cd in Nagapattinam, and Mg > Fe > Zn > Cu > Hg > Pb > Cd in Tuticorin. Bioaccumulation of metals showed preferential accumulation in muscle tissues of fish species viz., Otolithus ruber, Siganus javus, Atule mate, Sardinella gibbosa, Nemipterus japonicus, Lutjanus fulviflamma, Rastrelliger kanagurta, Gerres filamentosus, Sphyraena obtusata, Selar crumenophthalmus, Upeneus moluccensis, Plicofollis dussumieri and Sillago sihama. The metal concentrations were found dependent on species-specific, behaviour of feeding, pattern of swimming and genetic tendency or other factors such as age and geographical distribution. The metal concentration varied from the fish species. Principal component was analysed and found that heavy metal concentrations detected in the study do not pose a major risk to human being. The present work suggests to continuously monitor the polluted areas for a long-term basis, as the fishes show a tendency of accumulating even non-essential metals from polluted waters.