Mercury and plastic from rivers and lakes can not only harm local ecosystems but also pose a danger to humans, as river water is actively used by humans. And when it reaches the sea, the carcinogen can accumulate in seafood and be ingested by humans. In Greenland, in just the last couple of years, thousands of large blue lakes have turned brown; they’ve filled with stinking mud that releases carbon into the atmosphere. Another study found that mercury levels have nearly doubled in virtually all the world’s major rivers. And the first data collected on plastic pollution in the Amazon basin in 2025 reveals its widespread prevalence.
Greenland’s natural and climatic conditions are increasingly causing concern among climatologists, geophysicists, and biologists. Specifically, accelerated melting of the ice sheet could lead to the collapse of all the island’s ice shelves and the destabilization of the rock masses. And now another problem has come to light: alarming changes have occurred in the lakes. In just a couple of years, thousands of large blue lakes have turned brown; they’ve filled with stinking mud, releasing carbon into the atmosphere.
The University of Maine’s Climate Change Institute believes that atmospheric “rivers”—streams of water vapor that transport vast amounts of moisture—may be to blame. A series of such events occurred in the fall of 2022. Scientists calculated that 7,500 lakes in West Greenland experienced unprecedented environmental changes that season following record heat and abnormal precipitation, reports Planet Today.
In the summer of 2023, a team of specialists examined some of the affected lakes and discovered that the water had undergone radical changes in its physical, chemical, and biological properties. Heatwaves caused autumn precipitation to fall as rain rather than snow. Furthermore, high temperatures thawed permafrost in places, releasing abundant carbon, iron, magnesium, and other elements. Heavy rains washed these substances into the lakes, significantly altering their properties. The influx of organic matter and nutrients, in turn, accelerated bacterial growth in the lakes, causing the water to turn brown and acquire an unpleasant taste and odor. This became a problem, as the lakes provide residents with fresh drinking water.
GISMETEO: Water quality has sharply deteriorated in thousands of lakes in Greenland.
“Increased levels of dissolved organic matter can interact with drinking water treatment processes, forming chlorination byproducts called trihalomethanes, which can be carcinogenic,” climate scientists stated. As the lakes became darker and turbid, the lack of light led to a sharp decline in plankton biodiversity and disrupted the region’s carbon cycle. The unusual conditions reduced the amount of phytoplankton, which absorbs carbon dioxide from the atmosphere through photosynthesis, but increased the amount of plankton, which releases carbon. As a result, CO2 emissions—a greenhouse gas that causes climate warming—from the lakes increased by 350%.
Researchers believe the initial wave of extreme weather may be linked to atmospheric rivers. Their movement led to a dramatic shift in freshwater ecosystems on the island, but now scientists are eagerly awaiting whether the situation will recover at the same rate. “It was such an overwhelming climate force that it caused all the lakes to respond similarly,” the scientists say. “When it comes to recovery, will it be the same for all the lakes or different?”
Using a computer model and geological measurements, scientists compared mercury concentrations in the world’s major rivers today with their pre-industrial revolution levels. They found that mercury levels have nearly doubled in virtually all regions.
Mercury is one of the most well-known toxic and carcinogenic elements on the periodic table. Accumulating in bones, it can harm the human hematopoiesis and nervous system. Industrial development has contributed to an increase in its concentration in the atmosphere, water, and upper soil layers. Science has little idea how emissions have changed over the past centuries, although studying such trends would clearly demonstrate whether current levels of mercury in the environment pose a growing health risk.
Although previous studies focused on analyzing carcinogen concentrations in the atmosphere, soil, and seawater, they largely ignored rivers—a major mercury pathway, effectively serving as a conduit for wastewater from municipal and industrial sources. Mercury from rivers can not only harm local ecosystems but also pose a danger to humans, as river water is actively used by humans. And when released into the sea, the carcinogen can accumulate in seafood and be ingested through human consumption.
Therefore, scientists decided to study how mercury concentrations in the world’s major rivers have changed over the past two centuries. Ecologists developed a computer model based on geological data dating back to 1850, when industrialization was just beginning and human intervention in nature was less significant. Using this model, they calculated natural mercury levels and their changes due to human activity.
Modeling showed that the most significant changes are observed in the rivers of South and North America, followed by Southeast and East Asia. Before the Industrial Revolution, approximately 390 megagrams of mercury were released into the world’s rivers annually; today, this amount has doubled and sometimes tripled in these regions. Small-scale mercury-based gold mining (ASGM) has played a particularly significant role in South America. The Amazon basin alone emits over 200 tons of mercury annually—75% of which is due to human activity.
A decrease in concentrations has been recorded in the Mediterranean region; scientists attribute this trend to the construction of dams that retain mercury-containing sediments.
The overall trend of increasing mercury levels in rivers demonstrates the need to regulate toxic emissions, which are potentially hazardous to both human health and the entire biological community. Scientists believe their work could serve as a basis for legislative regulation of water pollution with this toxic substance. The study was published in Science Advances, according to InScience.News.
The first data collected on plastic pollution in the Amazon basin in 2025 reveals its widespread distribution. The review included 52 studies published since 2000, covering nine countries in the region. Scientists have documented the presence of plastic in rivers, soils, and animal bodies.
According to Jessica Fernandes de Melo of the University of Santa Cruz (Brazil), traces of microplastics are found even in species living deep in the forest and having little contact with humans. She also noted that some birds use plastic elements in nest construction.
The study points to a lack of effective recycling and waste management systems in many municipalities. As a result, plastic is gradually accumulating in the environment. Two-thirds of the animal species found to contain plastic are consumed by local residents, raising questions about potential health risks.
The particles were most often found in the digestive system of fish. However, it has not yet been determined whether they penetrate muscle tissue, which constitutes the bulk of the food consumed by humans. It is also emphasized that plastic contamination of drinking water has not been adequately studied.
The review’s authors note that existing data indicate the widespread presence of plastic in Amazon ecosystems, but research remains insufficient. The first targeted studies in this area only began in 2018, and many areas remain uncovered. Scientists are primarily focusing on the main river channel, while tributaries and remote areas require further study.
Experts emphasize the need for in-depth research into nanoplastics and expanded monitoring in understudied areas to more fully assess the impact of pollution on ecosystems and the region’s population.
A satellite image from 2022 shows a shimmering trail of dried, chemically saturated mud left behind by a flood of wastewater that swamped a South African mining town, killing three people. It’s a golden river of potentially toxic waste, meandering through the countryside after a deadly diamond mine disaster in South Africa.
On September 11, 2022, a dam at the Jagersfontein diamond mine suddenly collapsed, releasing a flood of mining waste known as tailings that engulfed the outskirts of the town and surrounding countryside, according to NASA’s Earth Observatory.
As Bloomberg reported, the disaster killed at least three people and injured around 40. According to Reuters, the flooding also destroyed dozens of homes, damaged cell phone towers, blocked roads, temporarily contaminated drinking water, and swept away hundreds of sheep.
The photograph shows a collapsed section of the dam’s southern wall. From there, waste flowed down the hillside in a massive wave 1.6 kilometers wide, eventually reaching the nearby Wolvas Dam and then flowing into the nearby Processpruit River.
A satellite image shows a meandering river of gold flowing out of a town in South Africa. A mine accident in the South African town of Jagersfontein released a mass of potentially toxic waste, known as tailings, into the surrounding countryside. NASA/Landsat/Lauren Dauphin
In total, the dried waste covered approximately 26 square kilometers of agricultural land. According to the Earth Observatory, some sections of the Processpruit River also appear to have widened, suggesting that the flow of mining waste may have eroded the riverbanks.
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It is unclear whether any tailings remain in the area, but experts initially predicted that the dried waste would quickly disintegrate and be either blown away by the wind or washed away by rain.
According to Earthworks, a US-based nonprofit that supports communities affected by mining and fossil fuel extraction, tailings are a murky mixture of dust, crushed rock, water, and other byproducts left behind after mining operations.
According to Earthworks, excess sludge often contains traces of metals such as copper, mercury, cadmium, and zinc, as well as other compounds including petroleum, sulfuric acid, and cyanide. This composition makes the mixture appear golden when viewed from above, but it is also potentially lethal to animals.
The diamond mine, once the deepest hand-dug mine in the world, was also damaged by the flood and has not reopened since. It is unclear whether it will ever reopen.
According to the Cape Town Diamond Museum, the mine produced two of the world’s eight largest diamonds – the Excelsior Diamond and the Reitz Diamond, also known as the Golden Jubilee Diamond.
In early February 2025, the Sarandí Canal in Argentina turned blood red. Authorities suspect that a toxic substance used in dyes leaked into the canal, located on the outskirts of Buenos Aires.
A canal in Argentina turned blood red and began emitting a foul odor last week, according to local media reports, suggesting a toxic substance used in dyes may have leaked into the water.
The Sarandí Canal, or Sarandí Creek, flows through an industrial area of the Avellaneda municipality on the outskirts of Buenos Aires, the country’s capital. Local residents feared a toxic spill. One reported waking up to a strong odor and noticing the water had turned red, the Associated Press (AP) reports.
The Sarandi Canal turned blood red on the outskirts of Buenos Aires. Juan Mabromata/AFP via Getty Images
“It looks like a stream of blood. We’ve never seen anything like it,” city resident Maria Dukomls told the Associated Press.
The area along the canal is home to tanneries and other businesses that produce leather from animal hides. Some parts of the Sarandi River also border a nature reserve, according to the German broadcaster GW News.
According to the Associated Press, Avellaneda authorities suspect the water contained the toxic substance aniline, used in dyes and medicines. Aniline is usually colorless but can darken and change color through oxidation—a chemical reaction with oxygen. This substance is extremely toxic to aquatic life.
This is not the first time the Sarandi River has taken on an unusual color: it has previously turned both green and purple, AP reports.
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