Visitors to the Alter do Chão district of Pará usually enjoy the clear, blue waters of the Tapajós, which have earned it the nickname “Amazonian Caribbean”.
But those who spent the last New Year’s Eve in the district – one of the main tourist destinations in the Amazon – found something different: the waters that bathed the beaches of white sand were murky and muddy.
The phenomenon has alarmed residents and tourism agencies, who fear damage to the district’s main economic activity and the health of residents.
They cite fears that the change in water is a consequence of increased mining in the middle course of the Tapajós, Brazil’s biggest illegal mining hub. Mining contaminates rivers with mercury, which can cause neurological diseases.
Satellite images show that in recent years there has been a vertiginous growth of gold mining in the Middle Tapajós, a region that is a few hundred kilometers from Alter do Chão.
‘Waste harmful to health’
“Tapajós is dying!” protested on Instagram in January, the local tourism agency Poraquê.
“Muddy waters, full of waste harmful to health, are being dumped mercilessly,” the agency added, attributing the mud to “irregular mining by numerous mines along the river.”
Other entities have published similar complaints.
The first warnings about the change in the color of the river were made by doctor Erik Jennings Simões and by Caetano Scannavino, coordinator of the NGO Projeto Saúde e Alegria.
Both residents of Santarém, a municipality that encompasses Alter do Chão, they posted aerial photos on social media at the end of December that showed the Tapajós with murky waters. The images were taken by plane by Simões.
Scannavino, who has lived in the region since the 1980s, tells the BBC that in past decades the waters of the Tapajós in Alter do Chão used to be muddy for a few months a year — but rarely in December.
The phenomenon is associated with the period of more intense rains, usually between January and March, when it loses strength and the waters turn blue again.
But Scannavino says he believes that mining is reducing the “window of clear water” in the river and cites data on the explosion in activity in the Middle Tapajós. This increase, according to him, has been stimulated by statements and initiatives by the Jair Bolsonaro government that are sympathetic to prospectors.
In December, the NGO Greenpeace released the results of monitoring the rivers that cross the Munduruku and Sai Cinza indigenous lands and flow into the Tapajós.
According to the survey, since 2016, illegal mining has destroyed 632 kilometers of rivers within these territories.
Greenpeace says that the impact is equivalent to that caused by the rupture of the dam in Mariana (MG), in 2015, when 633 kilometers of the Doce River were affected.
Illegal mining has been present in the Middle Tapajós since at least the 1980s. Today, however, the activity has become mechanized: backhoe loaders facilitate the turning of land on the banks of rivers, opening large scars in the forest.
The upturned areas are exposed, without any vegetation. The rains then carry the clay from the soil into the rivers.
Rivers of different colors
But could the same mining mud be behind the murky waters of the Tapajós in Alter do Chão, a district that is a few hundred kilometers away from the illegal mining?
For geologist André Sawakuchi, a professor at the Institute of Geosciences at the University of São Paulo (USP), the change in the color of the waters can have two explanations.
A specialist in Amazonian rivers, Sawakuchi says that there are rivers in the region whose waters are naturally muddy (or “white”, as they say in the region).
This is the case, for example, of the Amazon River, where the Tapajós itself empties 30 kilometers east of Alter do Chão.
But he says that all the naturally muddy rivers in the region originate in the Andes mountain range, in areas of rugged relief and little forest cover. When it rains at the headwaters of these rivers, the clay from the soil flows into the waters, making them cloudy.
There are also Amazonian rivers with naturally dark waters, such as the Negro, a color that is due to the large amount of organic matter that they access in the floods.
Finally, there are rivers with naturally clear waters, which tend to be born in less rugged areas, with sandy soil and little clay.
This is the case of the Tapajós and its tributaries, such as the Jamanxim, the Crepori and the Ratão.
Today, however, several of these tributaries have murky waters year-round because of mining, says Sawakuchi. The Tapajós also becomes more turbid at the points of contact with these rivers.
But the geographer says that the mud from the mining tends to settle in the Tapajós bed before reaching Alter do Chão.
This mud could only reach Alter do Chão, he says, if there was a difference between the flows of the Tapajós and the Amazon that would allow the Tapajós water to advance more intensively towards the Amazon.
On the other hand, an imbalance in the flows in favor of the Amazon could cause the naturally muddy water of the Amazon to advance to Alter do Chão — which would also explain the change in the color of the river.
“When the Amazon is filling up, it invades the Tapajós. This invasion begins in the rainy season (November) and can be more or less intense, depending on the flow of the Amazon”, says Sawakuchi.
This year, both Amazonas and Tapajós have levels above their historical averages.
Therefore, according to Sawakuchi, the best way to determine the cause of the muddy water in the Tapajós in Alter do Chão would be to analyze the content of this water. This analysis would be able to distinguish the clay from the Amazon from the mud from mining, says the geologist.
There is currently no news that any government institution or entity is carrying out this analysis.
mercury in the blood
Although the mining mud is not reaching Alter do Chão, a survey by Ufopa (Federal University of Western Pará) indicates that the population of Santarém has high levels of mercury in their blood — which could be an impact of illegal mining on the Tapajós.
Coordinated by biologist Heloísa Meneses, a professor at the Institute of Collective Health at Ufopa, the survey revealed that 80% of Santarém residents have a level of mercury in their blood above that recommended by the World Health Organization.
The study has already analyzed blood samples from about 500 people, aged between 18 and 80.
The results were similar to those detected by the Oswaldo Cruz Foundation (Fiocruz) in a study with residents of the Middle Tapajós – this, indeed, a region directly impacted by mining.
Mercury is used to facilitate the agglutination of gold and, taken to rivers, can contaminate microorganisms and fish.
Other possible sources of the substance, according to the researcher, are deforestation and fires, which can “activate” the inorganic mercury deposited in the soil or river bottoms, allowing its absorption by the food chain.
The population is impacted by the substance mainly through the consumption of contaminated fish, according to Meneses. And fish contaminated in a mining region can travel several kilometers before being caught and consumed – which also puts residents of regions far from the points of contamination at risk.
She claims that mercury causes damage to the central nervous system and, in large amounts, can lead to death. The substance also harms the heart, kidneys and liver, and can contaminate babies through the placenta.
river dependency
For many riverside dwellers who live on the banks of the Tapajós, however, giving up eating fish is not an option.
Djalma Moreira Lima, a resident of the Suruacá community, located in the Tapajós-Arapiuns Extractive Reserve, a few hours by boat from Alter do Chão, tells the BBC that fish are the main source of protein for local residents.
“Our livelihood is fish, manioc, corn, beans. We survive on these foods,” he says.
Lima says the Tapajós had clear waters when it arrived in the region in 1984.
“You could see up to two meters deep. There were plenty of fish, you didn’t have to go far to fish”, he says.
Today, however, he says that there are fewer fish and that the river has become “drier”. According to him, the “land that comes from mining” settled on the bed and reduced the depth of the waters.
He says that in September, the month with the lowest flow of the river, some boats run aground – which did not happen in the past.
He says that, at the deepest points, the Tapajós used to be “almost black, black, a river you liked to bathe in”, but says that today you can see “several white spots” in the waters.
“It’s like milk in coffee,” he describes.
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