Attempts to increase freshwater biodiversity are unlikely to bear fruit without further reductions in zinc and copper, according to research from the UK Centre for Ecology & Hydrology (UKCEH).
A new paper (https://pubs.acs.org/doi/10.1021/acs.est.4c06849), published in the Environmental Science & Technology journal, has linked improvement in freshwater biodiversity in England’s rivers to reductions in pollution of zinc and copper, largely due to the decline of coal burning and heavy industry.
The study found that although concentrations of ammonia and organic matter – strongly associated with sewage effluent – are important to influencing invertebrate diversity, the correlation with zinc and copper was strongest. The highest metal concentrations are found downstream of abandoned mines and are still impacting biodiversity.
Professor Andrew Johnson, an environmental research scientist at UKCEH who led the study, said: “There is a widespread desire by the public to improve water quality and biodiversity in our rivers but the problem for policymakers is what steps would be most likely to achieve results. Our study provides strong evidence that concentrations of zinc and copper have the biggest influence on invertebrate species richness, so future attempts to increase freshwater biodiversity are unlikely to bear fruit without further reductions in these metals.”
The work examined a wealth of Environment Agency data – 65,000 individual observations relating to pollutant measurements and invertebrates from 1,457 sites between 1989 and 2018.
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