Mercury pollution remains one of the most silent and persistent environmental threats. Recent research has highlighted how the degradation of coastal ecosystems can release this metal that has accumulated over decades, while in other parts of the world, direct exposure affects entire communities, from schoolchildren in Peru to indigenous populations in Bolivia. The data reveal that mercury not only remains in the environment but also recirculates when the ecosystems that store it are disrupted.
An international team, including researchers from the Blanes Center for Advanced Studies (CEAB-CSIC) in Girona, has published a study in the journal Earth-Science Reviews analyzing the role of mangroves, salt marshes, and seagrass meadows as mercury sinks. These ecosystems, known as blue carbon ecosystems, accumulate approximately 16 tons of mercury annually in their sediments, but when they degrade or disappear, they can release up to 26 tons each year. The research indicates that activities such as dredging, bottom trawling, coastal development, oil spills, and climatic phenomena like storms, floods, droughts, and marine heat waves are the main factors compromising this storage function.
Coastal ecosystems: mercury sinks in danger
The study, led by researchers from several countries, highlights that mangroves, salt marshes, and seagrass meadows act as natural filters that trap hazardous pollutants, including heavy metals like mercury. While these ecosystems remain healthy, mercury is immobilized in the sediments, but their destruction can reverse this process. Óscar Serrano, co-author of the study and director of the GAME group at CEAB-CSIC, emphasizes that conserving these areas is key to preventing mercury from re-entering the environment. According to the analysis, the most vulnerable regions are East Asia, Latin America and the Caribbean, sub-Saharan Africa, and several Pacific islands.
The threat in Peruvian classrooms
In Peru, a report by the Council for Environmental Health (CSA) has revealed that at least 2.647 students and school staff are exposed daily to dangerous levels of heavy metals in 39 schools in mining regions such as Huancavelica, Áncash, Cajamarca, Junín, and Lima. Soil analyses show concentrations of arsenic, lead, and mercury that exceed the country's Environmental Quality Standards. Many of these schools were built on the sites of former silver and gold processing mills, where cinnabar was used to extract mercury. Nicholas Robins, president of the CSA, is calling for further assessments and immediate action to reduce the risk.
Epidemiologist Enrique Ecos warns that prolonged exposure to these metals, especially in children and pregnant women, can cause irreversible neurological damage due to bioaccumulation. In December 2023, a court ordered the Peruvian government to declare an environmental emergency in Huancavelica due to mercury, lead, and arsenic contamination, but authorities have yet to implement concrete measures. The situation is particularly critical in areas of high poverty, where the lack of resources exacerbates the vulnerability of school-age children.
Mercury in the Bolivian Amazon: health impacts
In Bolivia, an inter-institutional study conducted in Amazonian communities has confirmed high exposure to mercury from the Illegal mining and contaminated fish. Hair analysis and de peces Studies from the area revealed that more than 50% of the inhabitants have liver damage, more than 30% have alterations in red blood cells, and 40% have genotoxic damage, that is, damage to DNA. Roger Carvajal, head of Experimental Biomedicine at the Seladis Institute, explained that the most frequent symptoms are fatigue, anemia and dizziness, although prolonged exposure can lead to degenerative diseases and cancer.
Researchers recommend completely eliminating the use of mercury in gold mining and replacing it with less polluting alternative technologies. The Bolivian Medical Association has urged the government to promote public policies based on scientific evidence, as the country lacks an agency to coordinate actions to address this problem. The study provides a scientific basis for authorities to adopt urgent measures to protect the health of Amazonian communities and the affected ecosystems.
The evidence gathered by these investigations shows that mercury knows no borders: from mangrove sediments on distant coasts to school floors in the Andes or the rivers of the Amazon, this toxic metal remains a global threat. Conserving coastal ecosystems, decontaminating school environments, and eliminating mercury from mining are necessary steps to curb its impact. Meanwhile, scientists insist that prevention and the restoration of natural habitats are the most effective tools to prevent mercury from recirculating and continuing to harm human health and the environment.