Arsenic was long used for treating wood, but this was banned in consumer products in 2004 due to concerns over its toxicity. However, the element continues to pose a risk in many areas as deposits naturally occurring in the ground and bedrock can contaminate water as a result of mining operations. One such area where this occurs is northern Sweden, but now researchers have identified a moss there that can quickly remove the harmful substance and make the water safe to drink.

It's not just drinking from waterways contaminated with arsenic that poses a risk to humans because the substance is also absorbed by plants, either from the soil or from arsenic-contaminated water used for irrigation. This can lead to high levels of arsenic in everything from rice and leafy greens, to wheat and root vegetables.

Now researchers from Stockholm University have discovered an environmentally friendly way of removing arsenic from water in the form of the aquatic moss Warnstorfia fluitans. This moss is found in various countries around the world, including Sweden, and was found to have the ability to absorb and adsorb arsenic from water in a very short time.

"Our experiments show that the moss has a very high capacity to remove arsenic," says research assistant Arifin Sandhi, who conducted the experiments. "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."

The research team says that the moss could be grown in streams and other watercourses contaminated with high levels of arsenic, thereby preventing high levels of the toxic substance entering the food chain.

"How much arsenic we consume ultimately depends on how much of these [contaminated] foods we eat, as well as how and where they were grown," says Maria Greger. "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."

The team's paper detailing the moss was published in the journal Environmental Pollution.

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