In 1990, the Voyager 1 probe took a historic photo of our planet, taken from more than 6 billion kilometers away: the probe was beyond the orbit of Neptune and showed the earth as a “blue dot”, the Pale Blue Dot As it was called in English – a certain color, as you can imagine, from the fact that the planet is covered for three quarters from Oceans. But if once these masses of water had been of another color? This is what a study published on Naturewhich explains The link between primordial bacteria, the birth of photosynthesis and, in fact, the color of the sea.
From the waters of Iwo Jima. The “doubt” regarding the color of the primordial oceans arose following an observation of the Japanese team that published the study: around the volcanic island of Iwo Jima (famous for being the scene of a bloody battle during the Second World War) are not blue, but have a greenish color. The waters around the island are rich in cyanobacteria, once known with the common name of “green-blue algae” (although not algae), but they are also rich in iron, to accurately oxidized iron.
Green waters bacteria. THE cyanobacteria dell’Archaneaneone (the largest chronological unit in which the age of the earth was divided) ranging from 4 billion to 2.5 billion years ago, were the first to develop photosynthesis, the process that allows you to use solar energy to produce energy. But with them there were also other bacteria, which instead of using sea water as a catalyst for photosynthesis used oxidized iron. AND These bacteria thrive in green watersas demonstrated by laboratory experiments conducted by the same team. The arrival of photosynthesis, therefore, led according to researchers to an accumulation of large iron concentrations, which colored the ocean surface of green and not of blue as today.
The oceans have become blue. Over the years of the Archean years, The color of the oceans changed just as a consequence of photosynthesiswhich began to release oxygen into the water. This began to bind to iron, oxidizing it. At a certain point, however, the “free” iron ended, and oxygen began to spread in the atmosphere, and radically change the way of producing energy of photosynthetic bacteria. That’s why, explains the study, The first cyanobacteria had two different ways of making photosynthesis: when there was so much iron, and the oceans were green, they exploited this metal; Once the iron ended, they moved to photosynthesis as we know it today.
And in the future? The study also suggests that the color of the oceans could change in the future: for example, If the sulfur levels should go up (perhaps following an intense volcanic activity), those bacteria that use sulfur for their metabolism – bacteria that are violaand in this way the color of the sea would change. However, there is talk of processes that require millions if not billions of years: in short, unless we will never see the purple oceans, and the earth becomes a “Purple Dot Pale“.
