A recent study by the National Institute of Oceanography, Goa, and the Academy of Scientific and Innovative Research, Ghaziabad, has revealed elevated levels of dissolved lead (dPb) in the northern and central Indian Ocean, significantly higher than in the Atlantic and Pacific oceans. The study highlights a clear north-to-south decreasing trend in lead concentration, with levels ranging between 23 to 114 picomoles (pM). This pollution is mainly attributed to human activities, particularly coal combustion in India and China, which have seen a 4.3 to 4.8 times increase in lead emissions over the past three decades.
The research, conducted using seawater samples collected during the winter monsoon and spring inter-monsoon seasons in 2020 and 2021, also noted that climatic phenomena such as the Indian Ocean Dipole and dust storms contribute to the deposition of lead in the southern Indian Ocean. Most lead enters the ocean through atmospheric transport from anthropogenic sources like industrial activity, coal burning, and vehicle emissions, especially in Asia. These emissions have increased the flux of lead into the Indian Ocean over the last 20 years, especially in the Bay of Bengal, where riverine input from the Ganga-Brahmaputra system also plays a major role.
The study underscores the environmental and health risks posed by lead contamination, emphasizing that even low-level exposure can be harmful, particularly for vulnerable populations like children and pregnant women. Lead is toxic and linked to neurological and behavioral disorders. As leaded petrol emissions decline, coal combustion and industrial processing have become the dominant contributors. The report calls for continuous monitoring of lead in ocean waters, given the high solubility and persistence of anthropogenic lead in marine environments.
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