Microplastics in Sundarbans Delta: Sources, Impact and Environmental Risks

Examine microplastics in Sundarbans Delta—microplastic pollution sources, impact on marine life, ecosystem health, and the urgent need for conservation measures.

Table of Contents

Context: A study by IISER Kolkata reveals that microplastics in the Sundarbans are acting as a “novel carbon reservoir,” releasing dissolved and biogenic carbon that threatens the efficiency of this critical blue-carbon ecosystem.

Microplastics in Sundarbans Delta

Concentration Levels: Microplastic levels ranged from 5 to 58 particles per liter.
Seasonal Surge: Concentrations were 40% higher during the monsoon, as heavy rainfall washed urban plastic waste and “colourless fragments” (weathered plastic) into the estuary.
Common Sources and Material Types: The study identified the specific types of plastic polluting the Mooriganga estuary:
- Fibres (50%): Predominantly sourced from synthetic textiles.
- Fragments: Derived from broken-down larger items.
- Chemical Composition: The most common materials found were Polypropylene (packaging) and Polyethene Terephthalate (water bottles).
Plastispheres: The researchers discovered complex microbial communities, known as “plastispheres,” living within the pits and grooves of the plastic particles.

Impact on Carbon Budget

Leaching Carbon: As they weather, they release dissolved organic carbon (DOC) into the water.
Biogenic Carbon: Microbes living on the plastic produce their own carbon, further adding to the “novel carbon reservoir.”
Bacterial Growth: This influx of plastic-derived carbon allows bacteria to multiply at unnaturally fast rates, interfering with the natural food web.

Impact on Blue-Carbon Ecosystems

Reduced Efficiency: The introduction of artificial carbon from plastics may make mangroves less efficient at their natural carbon-sequestering role.
Ecosystem Integration: Microplastics have now become a significant, permanent component of the Sundarbans’ carbon cycle, potentially shifting the ecological balance of the region.

Sundarban Delta

World’s Largest Delta: Formed by the confluence of the Ganga, Brahmaputra, and Meghna rivers, spanning approximately 10,000 sq.km across India (West Bengal) and Bangladesh.
It is the world’s largest contiguous mangrove forest. The name is derived from the Sundari tree (Heritiera fomes), a mangrove species known for its specialised roots called pneumatophores (breathing roots)
Global Recognition: UNESCO World Heritage Site, Ramsar Site, and Biosphere Reserve

Sundarban Delta

Mooriganga Estuary

It is a distributary of the Hooghly River (Ganga) in the South 24 Parganas district of West Bengal. It separates the mainland from Sagar Island.
It serves as a vital nursery for Hilsa fish and other commercially important marine species.
The estuary is highly influenced by semidiurnal tides, leading to constant mixing of freshwater and saline seawater, which creates a nutrient-rich environment.