The origin of water on Earth

The mass of the oceans on Earth, which corresponds to the mass of all the water on the planet, is only a small part (~ 0.02%) of the total mass of the planet. However, the existence of the ocean is enough to give the most impressive description of the planet Earth and thus separate it from the other planets of the solar system. However, the question of the origin of water on Earth, that is, why there is much more water on Earth than on other planets, has not been clarified.

Water covers about 70% of the Earth's surface.

Having enough water in a liquid state is the key to the emergence and evolution of life. The main questions about the origin of water: "When were the oceans formed?" and "Where did so much water come from?".


The ratio of deuterium and hydrogen in water
The main measurement value that tries to learn more about the origin of water on Earth is the D/H ratio, i.e. how much deuterium is in the water. Knowing how many HDO molecules are contained in the ratio of H 2 O molecules in water is a crucial test for most theories about possible sources of oceans on Earth, because it must correspond to the current D/H in the oceans today.

The first atmosphere of the Earth was dense (much denser than the current one) and extremely rich in hydrogen and partly water. Over time, atmospheric hydrogen reacts with oxides such as FeO, which were plentiful in the magma ocean on Earth, and this is one way to get more water.

Although the temperature of the atmosphere was high enough for all the water to be in a vaporous state, this equation describes how real the D/H ratio is. When the atmosphere cooled, the water vapor condensed to form an ocean. After that, this equation loses its meaning, because almost all of the hydrogen from the atmosphere is consumed (currently there is very little hydrogen in the atmosphere). It is often said that this initial amount of water comes from the solar nebula, because the D/H ratio of this water and the gas from which the atmosphere originated is, of course, the same. The atmosphere was formed from planetesimal gases, which created a protoplanet by accretion.. We also know that the D/H of the solar nebula does not correspond to the current value of D/H, and it is clear that as much water could not have formed as it is now in the oceans, as described above. So we need to look for other sources.

Possible sources
Possible water carriers are icy planetesimals, i.e. comets (the first idea) and rocky planetesimals from the asteroid belt, which also contain water (for example, carbon chondrites). It is known that the Earth's atmosphere was constantly replenished with new material as a result of the impact on the planet of very large planetesimals located at the very end of the size distribution. The first information about the comet's contribution to the oceans was obtained by comparing the ratio of concentrations of noble gases argon, krypton, xenon in the atmosphere of Earth, Mars and Venus with the concentration in a meteorite.the material is also in comet ice obtained in the laboratory. Laboratory studies have shown that the Ar/Kr/Xe ratios in cometary ice and in the ice of the Earth differ, which together with the Ar/Kr/Xe ratios in the atmospheres of the inner planets indicates that some of these gases hit the Earth and Mars. comets that formed at a temperature of ~ 50K, and the rest - as a result of the eruption of gases from the inside. The concentration of Ar/Kr/Xe in cometary ice depends on the temperature of ice formation. The amount of CO trapped by ice decreases exponentially with increasing reservoir temperature. It doesn't stay in the ice just below 24K, and H 2 is below 20K. This study shows that some of the water came to Earth through comets, but the main question is whether comets are the main source.

The values of D/H in various possible ocean sources on Earth vary. The average D/H value in carbon chondrites is very similar to that in modern seawater (and hence the value in rocky planetesimals). These ratios in the four comets for which we have this data and in the hydrogen in the solar nebula are 2 times higher or 7 times less than the values in the oceans of that time. Based on these results, the seawater probably also partly consists of the water of rocky planetesimals. Or one possibility is a suitable mass of water from comets, solar nebulae and rocky planetesimals. However, it seems that comets, which should be the most important source of the ocean (because they contain a large amount of ice and can be an abundant source of water when colliding with the Earth), still have higher D/H ratios than expected. Como en cualquier otro sitio web, para obtener el código promocional 1xBet es crear una cuenta. La idea es contar con un espacio seguro y personalizado para manejar tus apuestas. Esto lo consigues en el sitio web oficial completando unos pasos muy sencillos.Al ingresarla en tu cuenta, el sistema te identifica como un jugador calificado para recibir promociones adicionales para tus apuestas. Es una forma de premiar tu preferencia y fidelidad. Es común que los mayores beneficios sean otorgados a los nuevos jugadores y estos se activan durante el proceso de registro. Te dejamos el paso a paso en detalle a continuación.