Mercury Pollution from a Chloralkali Source in a Tropical Lake and Its Biomagnification in Aquatic Biota: Link between Chemical Pollution, Biomarkers, and Human Health Concern

ABSTRACT

Mercury is a highly toxic heavy metal that can cause adverse ecological and toxicological impacts through the mechanism of biomagnification. Hg accumulation in aquatic biota may thus also pose a serious threat to humans and other fish-eating animals. The present work observed the transfer of Hg from abiotic (water and sediments) to biotic (algae, aquatic macrophytes, and fish) components, belonging to different trophic levels in a tropical lake in India. Hg was analyzed in water, sediments, plants, and fish collected from different sampling points, receiving the discharge of chloralkali effluent. Hg concentrations increased significantly from lake water and sediments to algae and aquatic macrophytes. Statistical analysis (Pearson correlation) revealed a significant positive correlation between Hg in water and plants (r = 0.88–0.93; p < .01 and p < .05) as well as for Hg in sediment and plants (r = 0.50–0.83; p < .01 and p < .05). However, the increase in Hg concentration in fish was not significantly correlated with lake ambient water (r = 0.31–0.36), sediments (r = 0.29–0.33), and aquatic plants (r = 0.31–0.36). Results obtained encourage the use of naturally occurring wetland plants in designed systems like constructed wetlands to ameliorate Hg pollution in lakes, rivers, and ponds resulting from the discharge of industrial effluents, especially chloralkali effluent, hence reducing the human health risks associated with Hg.

Key Words:

• heavy metals
• chloralkali effluent
• biomagnification
• human health
• aquatic biota

ACKNOWLEDGMENTS

The author is thankful to the Council of Scientific and Industrial Research, New Delhi, India, for the financial assistance to Prabhat Kumar Rai in the form of a Junior Research Fellowship and Senior Research Fellowship. The author also extends his regard to Professor A.N. Rai, Vice Chancellor, Mizoram University, and Dr. B.P. Nautiyal, Reader, Horticulture, Aromatic and Medicinal Plants, Mizoram University, for their kind co-operation and support.