A team of researchers has discovered the existence of an underground river of mercury-contaminated water constantly flowing into the Mar Menor lagoon, a popular destination in Spain.
According to estimates, approximately one kilogram of mercury reaches the lagoon annually through this invisible flow, he writes
The study was coordinated by Céline Lavergne, a researcher at the Institute of Marine Sciences in Barcelona, and shows that the source of the pollution is a historical one. Mercury comes from past mining and agricultural activities, the effects of which continue to affect the environment even decades later, according to earth.
The Mar Menor, located in southeastern Spain, is the largest coastal lagoon in the western Mediterranean. The lagoon has beaches and is a popular tourist destination, known for its coastal areas and waters suitable for water sports.
Researchers have identified a network of underwater groundwater discharges beneath the lagoon floor, which transport mercury in concentrations up to 70 times higher than those in the Albujón River, the area’s main surface watercourse.
In areas where the groundwater mixes with the salt water of the lagoon, methylmercury is formed, a highly toxic form of mercury, which accumulates in the food chain.
Methylmercury gets into fish and other aquatic life, and their consumption can seriously affect human health. The World Health Organization warns that the substance can cause damage to the brain and nervous system, especially in fetuses and children.
Although the current levels of mercury in Mar Menor fish are not considered critical, scientists warn that the situation may worsen, especially in the context of climate change, which favors the decrease of oxygen in the water and the activity of bacteria that transform mercury into methylmercury.
The Mar Menor Lagoon has been experiencing massive algal blooms for years, caused by nutrient pollution from agriculture and sewage. These episodes have resulted in the death of fish and underwater vegetation, and the new discovery adds further pressure on the ecosystem.
According to the cited source, similar cases have been documented in other regions of the world, including the United States and Asia, suggesting that groundwater may represent an important but overlooked source of mercury pollution.
Researchers warn that although international treaties such as the Minamata Convention limit current mercury emissions, historical pollution remains a difficult problem to address. Solutions, they say, must include local interventions, constant monitoring and reducing other stressors such as nutrient pollution.
