Almost half of lakes in Europe polluted with phosphorous
According to scientists from the University of Southern Denmark, this is mainly due to phosphorus pollution.
The high levels of pollution present huge problems for both biodiversity and human society and efforts need to be made to speed up improvements in water quality, according to the researchers, who have produced a paper for the Water Research journal.
Associate Professor Kasper Reitzel, from the University’s Department of Biology, said, “Phosphorus is the biggest cause of water quality degradation worldwide, causing ‘dead zones’, toxic algal blooms, loss of biodiversity and increased health risks for the plants, animals and humans that come in contact with polluted waters.”
According to prof Reitzel - an expert in lake restoration - agriculture is amongst the main culprits for this pollution, which is due in part to run-off from inputs spread onto farm fields. Reitzel said phosphorus has been stock piled at an alarming rate in our lake bed sediments.
The scale of the problem is daunting, and even though attempts have been made on a huge scale to reduce runoff, humans are still pumping about 10 million tonnes of extra phosphorus into our freshwaters every year.
Reitzel said, “Long-term monitoring activities following the fate of phosphorus in lakes show that plants and animals don't recover for many years even if the phosphorus load drops. This is because phosphorus stored in bed sediments is released back to the water column and recycled in the lake."
Scientists from the university said that geo-engineering methods used to tackle the impacts of phosphorous pollution have not always yielded positive results, and expressed concern that authorities with responsibility for ages and freshwater bodies have used the approach uncritically. They have produced new guidelines in conjunction with the Danish Nature Agency which they hope will improve efforts to tackle pollution. ■