Sarah Biren

Sarah Biren

January 28, 2025

Researchers Discover Moss That Filters Arsenic, Turning Contaminated Water Into Safe Drinking Supply

Arsenic is an element famous for being toxic in large doses. Arsenic is indeed a naturally occurring element found in rocks and soil. Industrial activities, particularly mining, can exacerbate its release into the environment, leading to contamination of water sources. For example, they can lead to concentrations of arsenic in water sources. But researchers may have found a way to filter safe drinking water without any complicated technology. All they used was aquatic moss!

What is Arsenic and Where Does it Come From?

piece of arsenic on periodic table of elements
Source: Shutterstock

Long-term exposure to inorganic arsenic could cause a plethora of serious health conditions, including cancer, heart disease, and skin lesions. People can be exposed in industrial settings, through smoking tobacco, and through contaminated water supplies. This includes drinking it, and eating food prepared with — and irrigated by — this water.

According to the World Health Organization, many countries have areas with naturally high levels of inorganic arsenic in groundwater. These include China, India, Cambodia, Pakistan, Mexico, Argentina, Vietnam, and the U.S. 

“An estimated 140 million people in at least 70 countries have been drinking water containing arsenic at levels above the WHO provisional guideline value of 10 μg/L,” WHO says on their website. As a result, the organization considers it a major health concern, and many experts are searching for a solution.

Efforts to Reduce Arsenic in Everyday Life

ARSENIC CONTAMINATION IN DRINKING WATER - Alertness about dangerous Arsenic - Concept with magnifying glass
Source: Shutterstock

In 2004, it became illegal to use arsenic in wood products but it’s practically impossible to escape this compound entirely. Arsenic occurs naturally in the soil and bedrock in certain areas, such as northern Sweden, and mining can release it into water supplies. Foods like wheat, rice, root vegetables, etc. can absorb the compounds in the soil.

“How much arsenic we consume ultimately depends on how much of these foods we eat, as well as how and where they were grown. Our aim is that the plant-based wetland system we are developing will filter out the arsenic before the water becomes drinking water and irrigation water. That way, the arsenic will not make it into our food,” says Maria Greger, associate professor at the Department of Ecology, Environment and Plant Sciences at Stockholm University and leader of the research group. 

A Simple Solution: Aquatic Moss to the Rescue?

Warnstorfia fluitans
Source: Wikipedia

So Greger and her fellow researchers from Stockholm University tried a seemingly simple test. They used aquatic moss, Warnstorfia fluitans, which is native to Sweden. In the northern part of the country, mine tailing is an unfortunately common problem. But the researchers hope the moss could become an effective and environmentally-friendly answer.

The study’s results, published in Environmental Pollution in 2018, were very promising. The researchers collected the “floating hook-moss” from Lappland in northern Sweden. The moss is accustomed to scarce nutrition and low temperatures, making it a promising contender for phytofiltration. During the tests, the submerged moss accumulated relatively high amounts of contaminants without showing signs of toxicity. In fact, the moss rapidly absorbs up to 80% of the presented toxins within an hour, making the water safe for drinking. 

Read More: Solar Device Desalinates 20L of Drinking Water a Day with 93% Efficiency

Research Findings on Aquatic Moss Efficiency

Presence of Arsenic in drinking water - concept with the Mendeleev periodic table, old water brass faucet and magnifying glass
Source: Shutterstock

“Our experiments show that the moss has a very high capacity to remove arsenic. It takes no more than an hour to remove 80 per cent of the arsenic from a container of water. By then, the water has reached such a low level of arsenic that it is no longer harmful to people,” says research assistant Arifin Sandhi to Science Daily.

However, results became less impressive after further tests that involved higher concentrations of arsenic or additional compounds in the water. At that point, the moss became less effective at filtration, although it still continues to absorb arsenic.

Can Aquatic Plants Remove PFAS Too?

Landscape with sandy lake shore on a summer day.
Source: Shutterstock

Gregor further explored the potential of phytofiltration in a 2024 study published in the Journal of Environmental Management. The study shows that aquatic plants, particularly in large quantities, can reduce the content of perfluorinated alkyl substances (PFAS) in contaminated lake water. PFAS are synthetic chemicals commonly found in consumer products, such as stain-resistant fabric, fire-fighting foam, and non-stick cookware. 

These chemicals can build up in the body over time, and in-depth research about them is still in progress. However, according to the NIH, scientists have so far linked them to an increased risk of certain cancers, reduced immune system function, altered metabolism, and a risk of childhood obesity.

Read More: Is Drinking Water First Thing in the Morning Beneficial?

The Bottom Line

The skull on the bones, painted with water on the metal surface
Source: Shutterstock

Arsenic and PFAS exposure is a global concern, as is the provision of safe drinking water. But studies such as these provide hope of a solution. Moreover, aquatic moss may become a poetic solution from nature to heal nature. While the use of plants in removing PFAS is an area of ongoing research, specific studies on Warnstorfia fluitans for PFAS removal are limited. Further research is needed to determine its efficacy in this context.