Air quality stations accidentally collected valuable DNA samples for decades

An international team of researchers has discovered that thousands of ambient air quality monitoring stations around the world are unwittingly recording environmental DNA (eDNA).

Global warming has been known to cause severe loss of biodiversity, but researchers have struggled to quantify its effect due to the lack of infrastructure for tracking extinction rates - until now. 

A vital source of biodiversity data has been identified by new research in air quality monitoring stations. These stations have been collecting dust and pollution particles for decades. However, their filters have also accidentally collected valuable samples of eDNA, which can be used for analysing the progression of climate change. 

As part of this research, scientists found evidence of eDNA of over 180 plants and animals in only two air quality monitoring locations. Therefore, the data kept in all the stations across the world could have a massive impact on this field of study. 

“This could be a treasure trove of biodiversity data," said molecular ecologist Professor Elizabeth Clare of York University in Canada. "What we found by analysing filters from these monitoring stations is astonishing..”

Scientists have been looking at ways to measure biodiversity loss for decades. However, it was not until Professor Clare and Dr Joanne Littlefair of Queen Mary University of London proved it is possible to determine which species are present using eDNA sampled from the air, that scientists at the UK’s National Physical Laboratory (NPL) realised the potential of their devices.

The NPL team then contacted Littlefair and Clare to confirm whether the national air quality monitoring network in the UK was collecting eDNA during normal operation, and if this could be used to analyse biodiversity loss. The response was a clear "yes". 

“We were routinely collecting particulate matter looking to measure pollutants in air but when we saw the work of Clare and Littlefair, we realised maybe we were sitting on something much more valuable,” said NPL’s James Allerton. 

The team set up a test at an air quality station in London outside a large urban park, collecting samples for an hour, a day and a week, and compared them to eight-month-old samples from a public station in Scotland. 

Littlefair handled the samples from Queen Mary University of London, while Clare and grad student Nina Garrett analysed the data at York University.  

“We were surprised by the diversity of life we were able to survey with one approach, almost unheard in this field of science. In these two locations, we simultaneously detected the eDNA of 34 bird and 24 mammal species, a wide variety of insects, crops, pathogenic fungus, lovely wildflowers, ornamental garden plants and grasses,” said Clare.  

The team's analyses recovered eDNA from more than 180 different plants, fungi, insects, mammals, birds, amphibians, and other groups.

The species list included many “charismatic species such as badgers, dormice, little owls, and smooth newts, species of special conservation interest such as hedgehogs and songbirds, trees including ash, linden, pine, willow, and oak, plants like yarrows, mallows, daisy, nettles, and grasses, arable crops such as wheat, soybean, and cabbage.”

With only minor changes to current air quality monitoring protocols, these samples could be used for detailed monitoring of terrestrial biodiversity, relying entirely on a network that is already in operation.

The system could become a mechanism to measure biodiversity on land in a standardised repeatable way across entire countries continually every day, every week at thousands of locations.  

“The potential of this cannot be overstated,” Littlefair said. “It could be an absolute game-changer for tracking and monitoring biodiversity. Almost every country has some kind of air pollution monitoring system or network, either government-owned or private, and in many cases both. This could solve a global problem of how to measure biodiversity at a massive scale.”

The team is now working to preserve as many samples as possible with eDNA in mind. While the samples have already been collected, they say it will take a global effort to take full advantage of the biodiversity information they contain.