The world’s largest river basin is threatened by mercury pollution. Among the nine transboundary problems prioritized by the eight Amazonian countries, water pollution is considered the most serious. According to the United Nations Environment Program (UNEP), mercury from artisanal and small-scale mining (ASGM) is one of the main pollutants in rivers and represents a significant threat to biodiversity, aquatic ecosystems and the health of the population, as well as having unfavorable socioeconomic impacts.

Despite the legislation in force in the countries of the region, illegal and informal gold mining in the Amazon basin has increased in the last two decades. Pollution caused by illegal mining, by contaminating rivers and fish, has disproportionately affected indigenous peoples and riverside communities, impacting the food security of these populations, who depend on fishing as a source of subsistence.

The increase in records of environmental pollution and human contamination and intoxication means that Amazonian countries urgently need to implement public policies to monitor and control the use and movement of mercury in the Amazon Basin, in compliance with the Minamata Convention, to which they are all signatories. To stimulate and support the development of these policies, the Amazon Basin Project (ACTO/GEF/UNEP), which implements the Strategic Actions Program for Integrated Water Resources Management in the region, is developing the Overview of Mercury Pollution in the Amazon Region, a scientific study to quantify the sources of emissions and releases, according to the Mercury Inventory Toolkit developed by UNEP in 2013, and identify areas of risk and vulnerability to pollution.

Conducted in collaboration with IRD (Institut de Recherche pour le Développement), a French research and teaching institution, the Amazon mercury overview is being developed based on the geo-referencing of mercury sources and quantification of the volume of emissions and releases. When completed, it will be incorporated into the Amazon Regional Observatory (ORA), ACTO’s Amazon Information Reference Center.

According to Professor Jeremie Garnier, one of the researchers responsible for the study, the current phase of the landscape development is to develop a geo-referenced inventory based on governmental and non-governmental organization data on potential mercury emission sources.

“As far as possible, potential sources of mercury are being verified using satellite images to verify the existence of the activity responsible for the alleged emission, observing predictive variables such as changes in land use and occupation to delimit the areas where there is a higher probability of finding anthropogenic mercury, the one resulting from human activities,” explains Garnier.

The geo-referenced information will be available in the ORA, according to the platform’s specifications, and will be presented to the countries during a forthcoming event to be organized by the Amazon Cooperation Treaty Organization (ACTO). On that occasion, the methods and procedures for the next stage will be agreed upon, which is the exhaustive quantification of the volume of total mercury emissions and releases in the Amazon basin, using the Mercury Inventory Toolkit.

According to Garnier, geo-referenced and quantified data will provide estimates closer to the reality of mercury pollution in the region, as existing assessments, even those prepared for official documents under the Minamata Convention, are limited to identifying the main national sources of pollution without specifying emissions in the Amazon basin area. Given this lack of regional estimates, the first Minamata Convention Assessments (MIAs) conducted by countries indicate the need for more research to better understand the magnitude of the mercury problem in the Amazon, a gap that the Amazon Basin Project/OTCA-IRD partnership aims to overcome.

The mercury cycle and the presence of the metal in Amazonia

The preliminary report on the process of elaboration of the Mercury Pollution Overview in the Amazon Region, recently presented by researchers Jeremie Garnier and Henrique Roig, describes the origins and cycle of mercury and provides information on natural and anthropogenic mercury present in the Amazon. This information will be included in the regional overview to sensitize and raise awareness among governmental and non-governmental institutions and civil society about the danger of this metal and the need to monitor and control its use.

According to the report, mercury comes from a variety of sources, both natural and anthropogenic. Natural sources include erosion processes and volcanic eruptions, which release small amounts of mercury into water and soil. Anthropogenic sources include mining, agriculture, the medical and dental industry, the energy sector and others. The many industrial and technological uses of mercury demonstrate the importance of this metal in modern life.

Geologically ancient tropical environments, where soil formation is more intense, such as the Amazon, may be richer in natural mercury. Anthropogenic activities, such as deforestation, agriculture and burning of large areas of forest, are important sources of release of natural mercury accumulated and stored in the soil.

With no known biological function, mercury circulates in the environment in a complex form in liquid, solid and gaseous forms, participating in oxidation and methylation processes that can lead to highly toxic biochemical conversions, the most significant of which is methylmercury.

When released during the gold mining process, mercury can become airborne, traveling long distances and contaminating soils and waterways through dry or wet deposition during precipitation. Emissions from mining also occur through waste dumped on land and into water bodies. Whether airborne or deposited in water and soil, mercury emissions represent a significant risk to the environment and human health, contaminating mainly communities in the vicinity of mine-occupied areas, but also riverside communities and populations in distant cities.

“The metal cycling pathways, given their complexity, make it difficult to locate contaminated areas, even when it is possible to locate the emission points,” explains Professor Garnier.

First consolidated regional data

Based on the national data reported in the Minamata Convention Initial Assessments (MIAs) and National Action Plans (NAPs), the research team has consolidated in its preliminary report the first regional information on the areas most affected by mercury from mining, as well as the environmental, socioeconomic and human health impacts.

Scientific studies and information contained in the EIAs and NAPs show high levels of mercury in fish, soil and sediment samples and in the bodies of indigenous peoples and riverine communities in the cities of Beni and Pando (Bolivia), Madre de Dios (Peru), Chocó (Colombia), Napo and Zamora (Ecuador) and in the Guiana Shield, a region that also includes Suriname. Mining is intense in all of them.

In addition, the information contained in the EIAs and consolidated by the researchers shows that the main consequences of mercury contamination in the Amazon region are environmental degradation of aquatic ecosystems, making water resources unfit for human consumption, as well as soil and biota degradation and impacts on the health of the population.

Mercury emissions from mining contribute to ecosystem contamination and other environmental impacts, such as climate change associated with deforestation and soil erosion, leading to increased atmospheric concentrations of greenhouse gases. Records show that these environmental impacts have a lasting effect.

Regarding the consequences of mercury contamination on the health of Amazonian populations, scientific studies and EIAs mention damage to the central nervous system, such as loss of coordination and motor balance, renal, cardiovascular and immunological disorders, and alterations in vision and the respiratory system. High mercury levels in pregnant women, national assessments note, have impaired the development of fetuses and compromised babies’ cognitive function and motor skills, as well as their sensory perception.

The social impacts listed by the Amazon countries refer to the displacement of communities, loss of cultural heritage, as well as conflicts between mining communities and other stakeholders.

The MIAs also address the market and supply of mercury in the Amazon. According to data compiled by the Project, Amazonian countries do not produce mercury at significant levels and therefore depend on mercury imports. However, the amount of mercury imported and the routes by which it enters each country are poorly known and of concern to the respective governments.

“The lack of information is of concern because it can contribute to illegal trade and the use of mercury in artisanal and small-scale gold mining. As is the case worldwide, the importation of mercury can lead to illegal trade and crime,” the researchers state in the preliminary report.

Brazil had not published its MIA by the time this edition of the Águas Amazônicas newsletter went to press. Their data, therefore, do not appear in the preliminary report of this study.

The first consolidated data of the Mercury Pollution Overview in the Amazon Region, as well as maps with geo-referenced information and data to be measured on the volume of mercury emissions and releases in the Amazon, will be available at the Amazon Regional Observatory (ORA), hosted on the ACTO website.

The Minamata Convention on Mercury

Minamata is a coastal city in Japan that was the scene of one of the world’s most serious environmental catastrophes in the mid-20th century. Unbeknownst to the population, a chemical factory discharged a liquid containing high concentrations of methylmercury into the bay, contaminating the fish consumed by the city. About 5,000 people were affected. In addition to the victims with serious after-effects, the death toll was estimated at 900.

The Convention that bears the name of the Japanese city is the result of a worldwide negotiation process carried out by the United Nations Environment Program (UNEP). The agreement calls on the 140 signatory countries to develop a legally binding instrument to control the use and trade of mercury in order to protect human health and the environment.