Warns of Airborne Threat to Mangrove Ecosystem. The research demonstrate how the pristine air of sundarbans are getting affected with marine and terrestrial microplastics.
SUDARSHAN CHHOTORAY
KOLKATA: Even the most pristine corners of the Sundarbans are no longer untouched by
plastic pollution. A recent study conducted by the Indian Institute of Science Education and Research
(IISER) Kolkata, discovered airborne microplastics drifting above the protected mangrove forests — the
first such evidence recorded in any of India’s natural ecosystems.
The findings, now published in the international journal Science of the Total Environment, reveals that
the air above a completely uninhabited island in the heart of the Sundarbans contains tiny plastic
particles known as microplastics — invisible to the naked eye yet potentially harmful to plants,
animals, and humans alike.
The study was led by Dr Gopala Krishna Darbha, and his team which conducted an intensive eight-
day winter campaign earlier in January 2025 – using high-volume air samplers to detect PM₁₀-bound
microplastics. From their study they found an average of ten microplastic particles per 100 cubic
metres of air, an alarmingly high concentration for such a remote and protected region.
“What we are seeing is that the air over the Sundarbans is no longer pure,” said Dr Abhinandan
Ghosh, the study’s lead author. “Plastic particles are travelling through the atmosphere and reaching
even the most isolated mangrove forests. The air itself has now become a carrier of pollution.”
In their analysis, fibres and fragments emerged as the dominant types of microplastics, with black-
coloured particles — typically from discarded single-use plastic bags and degraded fishing nets —
being the most common. Using advanced μ-Raman spectroscopy, they identified polymer types such
as polypropylene (PP) and polyethylene (PE), materials widely used in packaging, textiles, and fishing
gear.
“The Raman spectra gave each particle a chemical fingerprint,” explained Mr Abhishek Mandal, co-
author and research scholar at IISER Kolkata.
“It was remarkable to match field-collected fibres with well-known industrial polymers like PP and
PE. That moment made us realise how human activity leaves a molecular signature even in a
supposedly untouched atmosphere.”
Mr Jay Karmakar, another member of the research team, added: “Processing the microscopic samples
was painstaking — every filter told a story of long-distance travel. It was humbling to see evidence
that plastics from our cities can drift all the way to these mangrove islands.”
As per research team, “What struck us further was how wind direction and local meteorology shaped
the movement of these plastics. During land-breeze hours, when winds blow from land towards the
sea, microplastics from the urban and rural regions of South Bengal — including Kolkata and the
buffer zones of the Sundarbans Biosphere Reserve — were carried deep into the forest. During sea-
breeze periods, the reverse occurred: marine winds brought plastic particles inland, lifted from
seawater by bubble bursting and wave action that inject microplastics into the atmosphere. We also
found that foggy conditions led to a sharp rise in microplastic concentration. Calm, humid air traps
pollutants close to the surface, allowing these plastic particles to accumulate near the mangrove
canopy.
Mr Swadhin Majumdar, another co-author of the study, observed: “Fog acts like a sponge for these
airborne plastics. Once trapped, they linger near the canopy, increasing the chance of deposition on
leaves and soil.”
This is the first scientific evidence showing that atmospheric processes such as fog formation and
land–sea-breeze circulation control how microplastics move between land and ocean.
“Our findings highlight a silent atmospheric pathway for plastic transport,” said Dr Gopala Krishna
Darbha, at IISER Kolkata. “The atmosphere connects continents and oceans; once microplastics enter
this cycle, they can reach anywhere on Earth. Protecting ecosystems like the Sundarbans now
requires understanding the air above them as much as the water around them.”
The discovery is alarming because these airborne plastics can settle on mangrove leaves, soils, and
waterways, threatening the fragile ecology of one of the world’s largest mangrove systems.
“Plastic has become part of the air we breathe,” reiterated Dr Ghosh. “Unless we curb open plastic
burning, mismanaged waste, and marine litter, even our most protected natural habitats will
continue to accumulate this invisible form of pollution.”
Through this study, the researchers at the IISER have urged policymakers to include airborne
microplastics within India’s National Clean Air Programme (NCAP) and coastal pollution frameworks.
Plastic pollution is no longer limited to land or water — it has become an atmospheric issue.
This discovery is both scientific and symbolic — a reminder that the fight against plastic pollution must
not only focus on what lies beneath our feet or flows through our rivers, but also on what now floats
silently in the sky above us.
