At a Glance
Four facts to hold on to.
Kidney role
Filtering pollutants from water.
Process
Denitrification turns nitrate into nitrogen gas.
India
101 Ramsar sites (August 2026).
UPSC 2022
Aquatic plants absorbing heavy metals.
Why “Kidneys”?
- Aquatic plants in wetlands absorb heavy metals and excess nutrients from water.
- This is the job that best matches the kidney comparison. Kidneys filter blood.
- The water cycle (runoff, percolation, evaporation) is hydrology, not filtration.
- Algae at the base of a food web is ecology, not purification.
- Sedimentation balance and soil stabilisation are real wetland functions, but a different job.
True or False: Aquatic plants absorbing heavy metals and excess nutrients best match the “kidney” comparison.
How the Cleaning Works
- Denitrification: microbes in wetland soil convert excess nitrogen into harmless nitrogen gas. Source: Wikipedia, Denitrification.
- Water hyacinth and Hydrilla verticillata have been used to remove heavy metals from wastewater. This is a form of phytoremediation. Source: Wikipedia, Phytoremediation.
- Filtration differs from sediment control, which is a separate wetland job.
True or False: Wetland soil microbes convert excess nitrogen into harmless nitrogen gas through denitrification.
Previous Year Questions
UPSC 2022 used the kidney analogy.
- UPSC 2022If rainforests are the lungs of the Earth, wetlands function as its kidneys. Which function best reflects this? The answer: aquatic plants absorb heavy metals and excess nutrients. View the question.
True or False: UPSC 2022 identified the water cycle as the function matching the kidney analogy.
True or False: Sedimentation balance and pollutant filtration are exactly the same wetland function.
India’s Ramsar Network
- As of August 2026, India has 101 Ramsar sites.
- They cover nearly 1.39 million hectares across 28 States and Union Territories.
- The newest is Glaw Lake in Arunachal Pradesh, announced on 3 August 2026.
- The Sundarban Wetland in West Bengal is the largest Ramsar site.
- Chilika Lake and Keoladeo Ghana National Park, both from 1981, are the oldest.
- Sources: The Environment, Glaw Lake and Wikipedia, Ramsar sites in India.
- The count changes as sites are added. Treat it as dated.
Why filtration matters for policy
- A healthy wetland upstream can improve water quality downstream.
- This is one reason India designates and protects wetlands, alongside biodiversity.
Think it through: why keep adding new Ramsar sites instead of protecting only the biggest and oldest wetlands?
Each wetland filters water for a different river system and downstream population. Protecting only flagship sites would leave many regions without that benefit. New sites, like Glaw Lake, spread protection more evenly.
True or False: As of August 2026, India has 101 Ramsar-designated wetlands.
True or False: The Sundarban Wetland in West Bengal is India’s largest Ramsar site.
True or False: Water hyacinth and Hydrilla verticillata have been used to remove heavy metals from wastewater.
Quick Q&A
Kidney role?
Filtering water.
Process name?
Denitrification.
Ramsar sites in India?
101 (Aug 2026).
Largest?
Sundarban.
Oldest?
Chilika and Keoladeo, 1981.
🎲 Practice: Wetlands as Earth’s Kidneys: How the Filtration Works
3 verified questions from this topic.
Question 1 of 1
Question 1 of 1
Question 1 of 1
Leave a Reply