By Abdullahi Lukman
A study conducted by the UK Centre for Ecology & Hydrology (UKCEH) has linked improvements in freshwater biodiversity in England’s rivers to reduced zinc and copper pollution, largely attributed to the decline in coal burning and heavy industry.
Published in Environmental Science & Technology, the study analyzed 65,000 observations from 1,457 sites between 1989 and 2018 and found that while ammonia and organic matter from sewage effluent influenced invertebrate diversity, zinc and copper had the strongest correlation.
The research suggests that reductions in zinc and copper pollution since the 1980s are likely due to three key factors: a decline in coal burning, which had contributed to atmospheric metal pollution; a decrease in heavy industry, which both emitted metals and discharged contaminated sewage; and a reduction in domestic products containing these metals.
Professor Andrew Johnson, the study’s lead researcher, emphasized that further reductions in these metals are critical for improving river biodiversity.
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Despite significant improvements in the 1990s and early 2000s, species richness has seen little further increase in recent years.
The highest concentrations of metals remain in areas downstream of abandoned mines, where they continue to impact biodiversity.
The UK government has set a target to reduce the length of rivers affected by metal pollution by half by 2038.
In addition to the reduction in metal pollution, improvements to wastewater treatment have also contributed to biodiversity gains, as seen in reduced levels of organic matter and ammonia in effluent.
The study’s use of long-term monitoring data provides a more direct understanding of the impact of pollutants on wildlife compared to previous lab-based experiments, offering valuable insights for policymakers working to enhance river health.
