Flower power: Pollen offers scientists clues to Brussels pollution

You might not realise it, but Brussels is home to a significant number of beekeepers. As well as harvesting nectar, bees also collect pollen from Brussels’ flower stock, which means they can help offer a picture of the extent of pollution in the capital.

“Bees from a single hive visit over four billion flowers a year,” explains Dr Laurian Parmentier, a researcher in the department for crop protection at Ghent University. He’s also part of Beeodiversity, an organisation that studies pollinators in the wider context of biodiversity.

“Bees provide a huge amount of data about the health of the ecosystem, more than any scientist alone could collect,” he says. “What we’ve done in this research is to analyse the pollen in beehives at different places in Brussels, measuring the presence of heavy metals and pesticides.”

The researchers divided the city into several zones, and the results show a mixed picture. The north and northwest, around the canal – historically a place of heavy industry – score poorly when it comes to contamination of pollen with heavy metals like lead and arsenic. Researchers even detected a strain of pesticide that’s banned.

A clearer picture

The origins of all these pollutants in the pollen is difficult to trace, says Parmentier. “Historical pollution from past industrial activities can play a role, but so does contemporary air pollution, such as emissions from traffic. Pesticides, meanwhile, can come from agricultural activity or from the use of these products in private gardens and parks."

Scientists analyse the pollen rather than the bees’ nectar because “pollen originates directly from the plant, and thus gives a clearer picture of the substances a plant has been exposed to during the whole of the growing season,” explains Parmentier. “Nectar, from which bees make honey, is just a short burst of sugar production by the plant, and has less value in relation to long-term pollution data.”

So Beeodiversity’s findings say less about the quality of Brussels’ honey than they do about the risk of gardening in the capital. “Allotments and city agriculture are increasingly popular and are heavily promoted, but if you look at these findings, there is reason to be cautious in certain regions of Brussels,” he says. “Leafy vegetables like lettuce and spinach are particularly vulnerable to pollution, both from the air and from the soil.”

Parmentier has some simple advice for urban gardeners wanting to improve the safety of their crops: “Don’t use any pesticides. There is a wide range of ecological alternatives available. The bees will thank you.”

Photo: Ingimage