Prelims
Pulicat Lake Ecosystem
Why in News:Pulicat Lake, India’s second-largest brackish water lagoon, is facing a severe ecological and livelihood crisis due to sand blockage at its estuary, which has halted seawater inflow and caused a sharp decline in fish population.
About Pulicat Lake:
- Location: Straddles the border of Tamil Nadu (Tiruvallur district) and Andhra Pradesh (Nellore district).
- Type: Brackish water lagoon (after Chilika Lake in Odisha).
- Formation: Formed by the backwaters of the Bay of Bengal separated by Sriharikota barrier island.
- Rivers Draining Into It: Arani, Swarnamukhi, and Kalangi rivers.
- Associated Institution: Satish Dhawan Space Centre (Sriharikota) is located on the island between the lake and the sea.
Ecological Importance:
- Important habitat for migratory birds like flamingoes and pelicans.
- Acts as a natural buffer against coastal erosion and storms.
- Supports biodiversity and traditional fishing livelihoods.
Current Issue:
- The estuary connecting the lake to the Bay of Bengal is blocked by sand, halting seawater exchange.
- Results in stagnant water, decline in fish stock, and livelihood loss for ~22,000 fishermen.
- Pollution, siltation, and encroachment further degrade the ecosystem.
Way Forward:
- Urgent desilting and restoration of the estuary.
- Sustainable lake management and stakeholder participation.
- Regulation of industries and encroachments around the lake.
Baratang Mud Volcano
Why in News: The Baratang Mud Volcano in the Andaman and Nicobar Islands erupted on 2 October 2025, after more than two decades of dormancy.
About the Volcano:
- Location: Baratang Island, North and Middle Andaman District, about 150 km from Port Blair.
- Type: Mud volcano – erupts mud, gases (mainly methane), and water, not molten lava.
- Cause: Gases from decomposition of organic matter deep underground push mud and water upward.
Last Major Eruption: 2005.
- Recent Eruption Impact: Created a 3–4 m high mound, spreading mud over ~1,000 sq. m area.
Significance:
- India’s only known mud volcano.
- A major geo-tourism site due to its geological uniqueness.
- Provides insights into subsurface gas activity and earth science research.
- Other Volcanic Activity in the Region:
Barren Island Volcano:
- India’s only active igneous volcano (~140 km from Port Blair).
- Eruptions recorded in 1787, 1991, 2017, 2022, andSeptember 2025.
- Caused by subduction of Indian Plate beneath the Burmese Plate.
- Baratang and Barren Islands highlight the tectonic and volcanic diversity of the Andaman region.
Precautionary Measures:
- Area sealed off by authorities for public safety.
- Geological Department conducting continuous monitoring and assessment.
Ethanol Blending Petrol (EBP) Programme
Why in News: The Union Home Minister hailed the Ethanol Blending Programme (EBP) as a transformative initiative that promotes rural prosperity by boosting India’s sugar cooperatives and reducing fuel imports.
About Ethanol Blending Petrol (EBP) Programme
- Launched: 2003
- Nodal Ministry: Ministry of Petroleum and Natural Gas
- Objective:
- To reduce dependence on fossil fuel imports.
- To cut greenhouse gas emissions.
- To promote the use of renewable biofuels derived from agricultural sources.
- Target: 20% blending of ethanol with petrol by 2025.
- Achievement: As of July 2025, India achieved 20% blending, up from 1.5% in 2014.
- Feedstock Sources: Sugarcane, maize, damaged food grains, and agricultural residues.
- Coverage: Implemented across India, except Andaman & Nicobar and Lakshadweep Islands.
Implementation:
- Oil Marketing Companies (OMCs) are responsible for procurement and sale of blended fuel.
- Ethanol blending specifications governed by Bureau of Indian Standards (BIS).
Policy Framework
National Biofuel Policy, 2009:
- Provided framework for EBP implementation.
- Initial target: 20% blending of ethanol and biodiesel by 2017.
Revised Policies (2018 & 2022):
New targets:
- 20% ethanol blending by 2025.
- 5% biodiesel blending by 2030.
About Ethanol
- Nature: Colourless, volatile, and combustible liquid.
- Production:
- Biological route: Fermentation of sugars using yeasts.
- Chemical route: Petrochemical process via ethylene hydration.
- Use: A clean biofuel that improves engine efficiency and reduces carbon emissions.
Li-Fi Internet System
Why in News: Gujarat-based Nav Wireless Technologies has successfully deployed the United States’ first commercial Li-Fi internet system in New York City, marking a breakthrough in optical wireless communication technology.
About Li-Fi (Light Fidelity):
- Definition: Li-Fi is a wireless optical communication technology that uses light waves from LEDs to transmit data at very high speeds.
- Mechanism: Data is transmitted through light pulses created by LEDs flickering at extremely high speeds (invisible to the human eye).
- A photodiode receiver converts these light pulses into electrical signals, which are then processed into usable data such as text, audio, or video.
- Medium Used: Visible, infrared, or ultraviolet light.
Comparison with Wi-Fi:
- Wi-Fi uses radio waves for data transmission, while Li-Fi uses light waves.
- Li-Fi can deliver speeds exceeding 100 Gbps, much faster than conventional Wi-Fi.
- It is more secure, as light cannot pass through walls, preventing external snooping.
Advantages:
- Provides ultra-high data speed and low latency.
- Ensures enhanced security within closed spaces.
- Offers 10,000 times larger bandwidth than radio frequency spectrum.
- Does not cause electromagnetic interference, safe for hospitals, aircraft, and factories.
- Promotes energy efficiency by combining data transmission with LED lighting.
Limitations:
- Requires clear line of sight between transmitter and receiver.
- Has a limited range, as light cannot penetrate walls.
- Ambient light (especially sunlight) can interfere with signal transmission, restricting outdoor use.
Nobel Prize in Physiology or Medicine
Why in News: The 2025 Nobel Prize in Physiology or Medicine was awarded to Mary Brunkow, Fred Ramsdell, and Shimon Sakaguchi for their pioneering discoveries on how the body regulates its immune system to prevent self-attack, establishing the central role of regulatory T-cells (Tregs) and the FOXP3 gene in maintaining immune tolerance.
Key Discoveries and Contributions:
Shimon Sakaguchi (1995):
- Discovered regulatory T-cells (Tregs) — a subset of CD4⁺ T-cells that suppress immune overreaction.
- Removal of Tregs in mice caused severe autoimmune diseases, while restoring them prevented illness.
Mary Brunkow and Fred Ramsdell:
- Identified the FOXP3 gene mutation in scurfy mice, leading to fatal autoimmune disorders.
- Traced similar mutations in humans with IPEX syndrome (Immunodysregulation Polyendocrinopathy Enteropathy X-linked).
- Established FOXP3 as the molecular switch controlling the differentiation and maintenance of Tregs.
Combined Outcome:
- Proved that immune self-tolerance depends on both deletion of self-reactive T-cells and regulation by Tregs.
- Reframed the immune system as a dynamic balance between activation and restraint, not a simple on/off response.
Applications and Modern Relevance:
- Autoimmune Diseases: Experimental therapies now aim to expand or stabilise Tregs to prevent harmful immune activation.
- Transplantation: Engineered Tregs are being tested to improve graft acceptance.
- Cancer Therapy: Efforts are underway to reprogram or deplete tumour-associated Tregs to boost anti-tumour immunity.
Broader Impact:
- Opened new frontiers in targeted immunotherapy and cell-based treatments.
- Highlighted the role of private-sector research in fundamental scientific discoveries.
Quick Fact:
- FOXP3: A transcription factor gene on the X chromosome; essential for the development and function of regulatory T-cells.
- Tregs (Regulatory T-cells): Maintain immune tolerance and prevent autoimmunity by calming overactive immune responses.
