UAB Study Warns of Toxic Metals in Mar Menor Due to Historic Mining Practices
A recent study from the Autonomous University of Barcelona (UAB) has raised alarms about toxic metal accumulation in the Mar Menor lagoon in Murcia. This concern stems from historical mining practices, specifically from the Cartagena-La Unión mining district, which was active from the late 19th century to the mid-20th century.
Toxic Metal Levels Detected in Mar Menor
The research, conducted by the UAB’s Department of Physics in collaboration with the Institute of Environmental Science and Technology (ICTA-UAB), found that sediments in Mar Menor exceed toxicity limits for various metals. These include:
- Lead
- Arsenic
- Zinc
- Mercury
- Copper
- Silver
These findings indicate that the lagoon, the largest saline lagoon in Europe, has metal concentrations surpassing those in similar coastal ecosystems worldwide.
Historical Context of Contamination
Researchers reconstructed the historical contamination of the lagoon, pinpointing the mid-20th century as a peak period for metal accumulation. Although the ban on mining waste discharge in 1955 reduced some metal levels, others persisted due to urban runoff and residual mining activity. Heavy rains have further exacerbated this issue, reintroducing contaminants into the lagoon even after the mines closed in the 1990s.
Current Status and Future Risks
Estimates suggest that thousands of tons of toxic metals are currently stored in the Mar Menor’s sediments. While these levels haven’t substantially affected marine life yet, the study warns of potential future risks. Current surface concentrations of metals are lower compared to much of the 20th century.
However, climate change poses a significant threat. Increased nutrient influxes from human activities may lead to eutrophication. This, combined with sediment resuspension during extreme weather events, could release toxic metals back into the ecosystem.
Such scenarios could jeopardize the biodiversity of Mar Menor and adversely affect aquatic organisms. The researchers advocate for ongoing monitoring and management strategies to safeguard this essential ecosystem.
