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Mercury levels in rivers have more than doubled since the industrial era, and experts warn that Spain is among the countries affected. A new international study, published in the magazine Science Advances, shows that the world’s rivers now carry around 1,000 metric tons of mercury to the oceans each year, up from 390 metric tons before 1850.

 

The rise, a 150% increase, is mainly caused by wastewater, soil erosion and mercury released by industry and mining. Though the research was led by Tulane University in the US, the findings have global implications, especially for countries like Spain with long coastlines, diverse river systems and active mining histories.

 

“Human activities have altered the global mercury cycle in every aspect,” said the study’s lead author, Yanxu Zhang. “Rivers have become a drainage channel for municipal and industrial waste.”

 

Mercury is a potent neurotoxin that builds up in fish and poses a risk to both wildlife and humans, especially those who eat seafood regularly. Spain’s rivers, particularly those flowing into the Atlantic and Mediterranean, are part of this global pattern. With fishing still an important part of life in coastal towns across the country, the findings raise concerns about long-term health and environmental impacts.

 

Spain has previously taken steps to reduce mercury pollution, especially after signing the Minamata Convention, a global treaty aimed at cutting mercury emissions. However, legacy pollution from past mining and industrial practices, especially in areas like Huelva and parts of northern Spain, continues to pose a challenge.

 

Interestingly, the research found that mercury levels in the Mediterranean area have fallen compared to pre-industrial levels, likely due to the construction of large dams that trap sediment and pollutants upstream. In Spain, this may include reservoirs that have helped limit downstream mercury flow, although more research is needed to confirm the effect locally.

 

With gold mining still common in parts of South America, Africa and Southeast Asia, many rivers outside Europe are seeing the sharpest rises in mercury. But researchers stress that no country is immune. Spain’s proximity to both the Atlantic and Mediterranean, and its place in global fish markets, make it a key player in the conversation around mercury safety and regulation.

 

As the researchers point out, monitoring river mercury could offer a quick way to assess whether pollution control efforts are really working – both here in Spain and around the world.

 

 

Image: Enrique/Pexels