England: New research from the University of Oxford, published ahead of World Rivers Day (September 24), finds that sewage flow into rivers has a bigger influence on water quality and the animals and plants that live in rivers than surrounding land development. The findings were published in Global Change Biology and Ecological Solutions and Evidence. Rivers play a significant role in the global water cycle, support important biodiversity, and are vital to human health. Water corporations in the United Kingdom, on the other hand, are permitted to discharge treated and untreated wastewater into rivers after severe rains (known as storm overflow).
In addition to the environmental repercussions, this poses major hazards to human well-being if the water is then used for drinking, recreational, or agricultural purposes.
Researchers from the University of Oxford’s Department of Biology investigated the effects of three different pollution sources (treated sewage discharge, agriculture, and urban run-off) on different aspects of river systems. The group tested four rivers in England, both up- and downstream of sewage discharge, over three different months.
The results demonstrated that treated sewage discharge was the best predictor of high nutrient levels, bottom-dwelling algae, and sewage fungus abundance, regardless of the type of land use (agriculture or urban) in the surrounding area.
Dr Dania Albini (Department of Biology, University of Oxford), lead author of the study, said,
Our study highlights the disproportionate impact that sewage discharge has on river quality, presenting an urgent need for a comprehensive action plan targeting the sewage discharge problem. Improvements to wastewater plants should be implemented along with more regulations. These efforts are crucial in safeguarding the integrity and safety of our rivers — fundamental elements of both ecosystems and human wellbeing.
Dr Michelle Jackson (Department of Biology, University of Oxford), senior author of the study, said,
There is ongoing debate about the cause of the poor ecological state of many rivers in the UK because it is difficult to disentangle different pollution sources. Here, we show that even treated sewage appears to have a stronger influence on river communities than pollution from the surrounding land. This important information should be used to prioritise the management and conservation of our rivers moving forward.
Nutrients exacerbate the decline of waterways by promoting the growth of harmful species and deteriorating others. This was seen in the rivers studied through a shift in macroinvertebrate and algae communities downstream of sewage input, with more tolerant groups such as cyanobacteria and worms becoming more abundant. This is concerning as cyanobacteria are well known for producing toxic chemicals that can kill many aquatic organisms. As a result of this, wastewater pollution has the potential to alter and degrade critical ecosystem processes via loss of critical species.
In the study, only one measurement –the abundance of the sensitive insect groups of mayflies, stoneflies, and caddisflies – was best predicted by agricultural land use. This suggests that water quality and river communities are generally more threatened by treated sewage discharge than pollution from the surrounding catchment, but agricultural pollution also needs to be kept in check.
These new findings come at a time of intense public concern over the state of the UK’s waterways. A recent investigation for the Observer found that more than 90% of freshwater habitats on England’s most precious rivers have been degraded by farming pollution, raw sewage and water abstraction.
James Wallace, CEO of the UK-based charity River Action, commented on the findings,
This important research demonstrates yet again the damage from unregulated water companies and agriculture. In addition to the catastrophic impact on wildlife from nutrient pollution, the public should be aware that sewage systems do not remove dangerous bacteria such as E.coli and intestinal enterococci from treated sewage. For instance, recent citizen science on the River Thames found that Thames Water’s outflows often have four to five times the safe levels of bacteria, which has likely caused serious illness in swimmers and rowers. When will the government make water companies and farms clean up their act, especially in places where human lives and sensitive protected habitats are threatened?
An early-detection system for spotting dangerous outbreaks
The researchers also developed a new method to allow early detection of potentially dangerous outbreaks of ‘sewage fungus’. This is a complex mix of fungus, algae, and bacteria which forms large masses when there are high organic nutrient levels. They not only cause unpleasant smells, but severely reduce oxygen levels in water which can adversely affect all river species, and cause mass fish mortality.
Currently, sewage fungus is only assessed visually, so it is only found once it has become large enough to already be having negative effects. The researchers developed a new method to allow early detection, an essential step to enable swift intervention to avoid extensive outbreaks. Their method uses imaging techniques and machine learning to rapidly identify sewage particles and sewage fungus in water samples.
The technique could be used as a ‘canary in the coal mine’ by both water companies and monitoring organisations such as the Environment Agency, and could prove to be a valuable tool in limiting pollution build-up and halting species decline.
Dr Michelle Jackson said,
Rapid identification of sewage fungus pollution events will allow early intervention which would help prevent any potential negative consequences for local wildlife.
(This story has not been edited by NDTV staff and is published from a syndicated feed.)
NDTV – Dettol have been working towards a clean and healthy India since 2014 via the Banega Swachh India initiative, which is helmed by Campaign Ambassador Amitabh Bachchan. The campaign aims to highlight the inter-dependency of humans and the environment, and of humans on one another with the focus on One Health, One Planet, One Future – Leaving No One Behind. It stresses on the need to take care of, and consider, everyone’s health in India – especially vulnerable communities – theLGBTQ population,indigenous people, India’s different tribes, ethnic and linguistic minorities, people with disabilities, migrants, geographically remote populations, gender and sexual minorities. In wake of the currentCOVID-19 pandemic, the need for WASH (Water,SanitationandHygiene) is reaffirmed as handwashing is one of the ways to prevent Coronavirus infection and other diseases. The campaign will continue to raise awareness on the same along with focussing on the importance of nutrition and healthcare for women and children, fightmalnutrition, mental wellbeing, self care, science and health,adolescent health & gender awareness. Along with the health of people, the campaign has realised the need to also take care of the health of the eco-system. Our environment is fragile due to human activity, which is not only over-exploiting available resources, but also generating immense pollution as a result of using and extracting those resources. The imbalance has also led to immense biodiversity loss that has caused one of the biggest threats to human survival – climate change. It has now been described as a “code red for humanity.” The campaign will continue to cover issues likeair pollution,waste management,plastic ban,manual scavengingand sanitation workers andmenstrual hygiene. Banega Swasth India will also be taking forward the dream of Swasth Bharat, the campaign feels that only a Swachh or clean India wheretoiletsare used andopen defecation free (ODF)status achieved as part of the Swachh Bharat Abhiyan launched byPrime Minister Narendra Modiin 2014, can eradicate diseases like diahorrea and the country can become a Swasth or healthy India.