Syllabus:

GS3: Conservation, Environmental Pollution and Degradation, Environmental Impact Assessment.

Context:

Recently, the United Nations Environment Programme (UNEP) released its Frontiers 2025: The Weight of Time.

More on the News

• It is the 7th Frontiers report of the UNEP. 
• The reports states that increased River and coastal flooding could expose people to legacy toxic pollutants that were long buried in water and sediments. 
• These legacy chemicals include heavy metals (like lead, cadmium, which are toxic at even low concentrations), certain persistent organic chemicals (like pesticides , synthetic chemicals, by-products of industrial processes and waste incineration). 
• Both these categories do not breakdown easily and are prone to accumulate in sediments of polluted rivers, lakes and estuaries.
• International and national regulations have banned some of them, but the older chemicals continue to stay even decades after the ban. 
• They can cause neurotoxicity, immunotoxicity, hepatotoxicity, reproductive toxicity, and various cancers.

Key Findings

Floods can resuspend, disperse and re-deposit the pollutants from the contaminated sediment, which can spread across the landscape and also can enter in food chain and may lead to Biomagnification.

Millions of tons of persistent organic pollutant waste from organochlorine and organofluorine production are deposited in landfills globally, with 4.8 to 7 million tonnes.

The report cited examples such as:

• The 2010 Pakistan floods submerged about a fifth of the country, washing away much of the 2,835 metric tonnes of stored obsolete pesticides and persistent organic pollutants.
• A catastrophic flood event in the Niger Delta in 2012 mobilised sediments contaminated with carcinogenic polycyclic aromatic hydrocarbons and deposited them over extensive portions of the floodplains.
• Hurricane Harvey hit Texas in August 2017, unleashing floodwaters that carried large amounts of sediment laced with high levels of carcinogenic chemicals and mercury into Galveston Bay.

The report explained that many regions are increasingly exposed to river and coastal flooding due to the upward trend in rainfall intensity and magnitude associated with tropical storms.

Indian context: 

• The report, which analysed various scientific studies, showed that Ganga, Hindon and Vaigai had concentrations of cadmium in sediments above which harmful effects on sediment-dwelling organisms are likely to occur frequently. 
• Cadmium is a carcinogen with potential endocrine-disrupting effects. It can cause kidney and bone damage as well as adverse pregnancy outcomes. 

UNEP calls for more studies evaluating the polluted sediments and other pollutant deposits in inland and coastal waters for their ability to release contaminants as this will be crucial to understand the potential hazards to human and environmental health from flood events. 

The experts called for flood-control infrastructure and protection measures guided by nature-based solution to reduce the number and intensity of flood events and associated damages. 

They also suggested traditional flood control measures such as polders, dikes, and retention basins to restore riparian ecosystems by allowing floodplains, wetlands and forests to re-emerge or establish water-conscious urban development.

But according to the Experts these measures simply relocate contaminated sediments and confine the problem to areas that pose less threat to human and environmental health. 

• So, they recommended developing river basin management plans that balance flood retention, river conservation and the multiple pressures on water resources.

The UNEP also stressed the importance of regular monitoring of river basin-specific pollutants.

• This involves continuously monitoring and reassessing the effectiveness of implemented measures and adjusting as science evolves as well as integrating local knowledge and engaging local communities, including citizen science efforts, in environmental monitoring and decision-making processes.

Frontier Report

• It is an annual publication by the UN Environment Programme (UNEP), which identifies and addresses emerging environmental issues.
• The UNEP Frontiers report series, which began in 2016, highlights issues that have the potential to become major global or regional concerns if not addressed early.

United Nations Environment Programme (UNEP) 

• UNEP is the UN’s leading environmental authority, setting the global agenda, promoting sustainable development, and advocating for environmental protection worldwide.
• UNEP drives transformative change by addressing the root causes of climate change, biodiversity loss, and pollution through seven interconnected programmes, all guided by a strong commitment to sustainability.
• Headquarter: Nairobi, Kenya.

Sources: DTE

https://www.downtoearth.org.in/climate-change/un-frontier-report-floods-can-release-legacy-chemicals-from-sediments-expose-people-to-its-harmful-effects