Some volcanic lakes are acidic and colored due to the geothermal activity occurring beneath the surface. Volcanic gases dissolved in the water can make the lake acidic, while the presence of minerals and microorganisms can give it unique colors.
Under active volcanoes, magma gases rich in sulfur compounds such as sulfur dioxide (SO₂) or hydrogen sulfide (H₂S) rise to the surface. When these gases mix with the water of the lakes located in the craters, they chemically combine to form acids, such as sulfuric acid. As a result, the water becomes hyper acidic. This phenomenon creates an extreme environment where few organisms can survive. Additionally, these chemical compounds give the water a very distinctive color, often green, turquoise, or even reddish, depending on the variety of gases and minerals present.
When a volcano emits gases like sulfur dioxide (SO₂) or hydrogen chloride (HCl), these gases react with the water in the lake. The result: the formation of sulfuric and hydrochloric acid, which strongly acidifies the water. Once acidic, the water then attacks the surrounding and underlying rocks, releasing dissolved minerals like iron, copper, manganese, or even aluminum. It is these minerals, once dissolved, that give the lake its incredible colors. For example, dissolved iron adds reddish or orangish hues, while copper tends to shift towards blue-green. Depending on the predominant minerals in the area, the color of the lake can range from bright turquoise to deep red or apple green. And there you have volcanic lakes that are both ultra-acidic and bursting with flashy colors.
Some very acidic volcanic lakes are home to extremophilic microorganisms that particularly thrive in these uninhabitable conditions for the rest of the living world. These highly resilient little creatures are capable of surviving in ultra-acidic, hot environments, or those rich in toxic metals. They use the chemical substances dissolved in the water, such as sulfur or iron, to produce energy. By transforming these chemical elements, they alter the composition of the lake's water and directly contribute to its stunning colors—often bright and flashy. Some of these extremophilic bacteria play essential roles in specific chemical reactions, further amplifying the spectacular colors observed in these volcanic lakes.
When the climate is hot and dry, the water of volcanic lakes evaporates quickly. In the process, it leaves behind a high concentration of minerals and dissolved salts, which alters the chemical composition of the remaining water. This decrease in volume increases the acidity and enhances vivid colors like turquoise, green, or red, making certain locations particularly spectacular. The more a lake loses water, the more concentrated the remaining minerals become, sometimes forming a crystallized crust along the edges of the lake. These deposits, rich in sulfur and other chemical compounds, directly contribute to these stunning and sometimes changing colors.
In some highly acidic volcanic lakes, the pH can reach extremely low values close to 0, similar to that of the acid found in a car battery.
Lake Nyos in Cameroon is not only famous for its colored water but also for its dramatic gas eruption in 1986, which abruptly released significant amounts of pressurized carbon dioxide.
The reddish or orange color in many of these acidic lakes comes from minerals such as iron oxide, often referred to as "volcanic rust" due to their resemblance to metal rust.
Some extremophilic microorganisms, adapted to the extreme conditions found in acidic volcanic lakes, greatly interest scientists due to their potential applications in the medical and biotechnological fields.
To some extent, yes, the sudden variation in pH, the increase in concentrations of certain dissolved minerals, or the appearance of specific gases (such as sulfur dioxide) can serve as useful indicators to anticipate a potential increase in underlying volcanic activity.
Yes, some microorganisms known as extremophiles, such as bacteria and algae specifically adapted to these environments, are capable of surviving, and even thriving, in the drastic conditions present in highly acidic volcanic lakes.
Yes, high acidity can cause the chemical degradation of surrounding rocks, alter adjacent soils, limit plant and animal diversity, and influence the chemical quality of groundwater and nearby watercourses.
The color variations observed in certain volcanic lakes can be attributed to changes in the concentrations of dissolved minerals, alterations in volcanic activity, or the seasonal proliferation of extremophilic microorganisms adapted to extreme acidic and mineral-rich conditions.
Sure! Here’s the translation: "Yes, swimming in acidic volcanic lakes is dangerous due to their extremely low pH, which can cause severe chemical burns. Additionally, potential toxic gas emissions pose a major health risk."
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