Biodiversity in England’s rivers improved as metal pollution reduced - UK Centre for Ecology and Hydrology
An improvement in freshwater biodiversity in England’s rivers was linked to reductions in pollution of zinc and copper, largely due to the decline of coal burning and heavy industry, say researchers.
Invertebrates are used as an important measure of a river’s biodiversity and health, and Environment Agency data show there was a widespread, significant increase in species richness across England in the 1990s and early 2000s. However, there has been little significant further improvement since then.
Therefore, a team of scientists led by the UK Centre for Ecology & Hydrology (UKCEH) looked for the possible reasons for this, using statistical modelling to investigate a wide range of different chemical and physical factors, such as temperature, river flow and landscape.
They examined a wealth of Environmental Agency data – 65,000 individual observations relating to pollutant measurements and invertebrates from 1,457 sites between 1989 and 2018.
The study, funded by the Natural Environment Research Council, has been published in the journal Environmental Science & Technology. It found that although concentrations of ammonia and organic matter – strongly associated with sewage effluent – were important to influencing invertebrate diversity, the correlation with zinc and copper was strongest.
Decline in coal and industry
The researchers say there are likely to be several reasons for the reductions in the amount of zinc and copper entering our rivers after the 1980s:
- Reduction in coal burning, an important source of atmospheric metals pollution that ends up in rivers through acid rain
- Decline in heavy industry, which emits metals into the atmosphere and discharges sewage containing pollutants that end up in rivers through treated and untreated effluent.
- Decline in domestic products containing zinc and copper, resulting in less metal pollution in sewage.
Posted On: 19/02/2025
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