WET Hydrology & Hydrogeology

While Earth may not have started as a Blue Planet, the best evidence that we currently have is that it has been a blue planet for at least 3.8 billion years. How it got here is still not fully understood. 

2 H₂ + O₂ → 2 H₂O

Hydrogen is the most abundant chemical element known in the Universe.  It is estimated to make up 75% of the mass of the Universe.

• On Earth, hydrogen is found in the greatest quantities as water.

• In gaseous form, it is present in less than 1 part per million by volume in the Earth's atmosphere.

• Any hydrogen in a gas form in the atmosphere rapidly escapes Earth's gravity and exits into space.  

Oxygen is the 3rd most abundant known chemical element in the Universe. 

• It makes up 21% of the Earth's atmosphere.

• 49.2% of the Earth's lithosphere

• 66% of the human body

Theoretically, it's easy to make water from hydrogen and oxygen gas. Mix the gases together and voilà - water. Following this recipe will more than likely result in a spectacular explosion.

To create water (2 H₂ + O₂ → 2 H₂O) , the reaction requires energy to break the covalent bond that hold H2 and O2 molecules together. The hydrogen cations and oxygen anions can freely react with each other, which they do because of their electronegativity differences, which re-form their chemical bond and create water. The reaction is exothermic produces energy in the form of heat.  

Europa, one of Jupiter's 60 moons, is one-fourth the diameter of Earth and has twice as much water as Earth. 

American Museum of Natural History