COVID-19 induced lockdown reduced metal concentration in the surface water and bottom sediment of Asia's largest lagoon

COVID-19 (hereafter COVID) induced lockdown provided a unique opportunity to evaluate the effects of human activities on coastal ecosystems. This study quantified the seasonal variations in concentrations of nine metals (Al, Cr, Cd, Co, Cu, Fe, Mn, Ni, and Pb) in surface water and sediment samples of the largest brackish water lagoon in Asia (i.e., Chilika Lagoon), comparing pre-and post-COVID scenarios. The COVID lockdown resulted in a wide variation in metals concentrations, with surface water showing 1 to 8.6-fold reduction in metals such as Al, Cr, Cu, Fe, Mn, and Pb, while sediment displayed a more modest reduction of 1 to 1.3-fold. Metals like Cd, Co and Ni were below detection limit in post-COVID water samples with a slight decrease (1-fold) in the sediments. COVID lockdown did not show any significant correlation with metal concentrations in water or sediment. This study provides baseline data for metal contamination in the surface water and sediment of the Chilika Lagoon.