Earths Chemistry kit

Geochemistry = chemistry of sediments, water and air help us trace the transfer of materials

Matter:

• physical material with mass
• molecules = two or more of the same elements
• compounds = two or more of different elements
• ions 
  • positive = cations
  • negative = anions

Dmitri Mendelev:

• looked at the relationship between elements
• organised them by mass and how they bonded with oxygen

Periodic table:

• 118 elements
• groups 
  • same number of electrons in the outer shell
  • vertical
• periods
  • elements with the same number of shells
  • horizontal

Covalent:

• no charge
• Water
  • dipolar
  • oxygen is negative
  • Hydrogen is positive
• Organic matter

Ionic:

• Exchange of electrons
• sodium chloride
• Ions have a charge

The addition of heat means the electron moves up to a higher energy shell

When the electron falls energy is emitted in the form of light

The higher the energy shell it falls from the shorter the wavelength so it will appear blue

Mass can only be rearranged not created or destroyed

• In a closed system the reactants mass will balance the mass of the product
• The earth is a closed system in the sense of matter

The nitrogen cycle is very important

Nitrogen:

• fertiliser is fixed by humans
• 78% of the atmosphere is nitrogen
• must be fixed to be bioavaliable but natural fiaxation is not enough to secure food globally
• nitrogen is fixed by plants
• fixated nitrogen is changed into nitrogen by bacteria in bogs, volatilisation under warm conditions, leaching of NO3 down into soil

The Gulf of Mexico dead zone:

• Fertilisers were used extensivly around the Mississippi river
• Nitrogen stimulates algal blooms which consume oxygen 
• There is then low levels of oxygen in the Gulf

Presevered and can be used to trace biogeochemical cycles and reconstruct past climates

• carbon fluxes
• water cycle

Stable isotopes

• number of p and n is chemically ctable

Radioactive isotopes

• the atom is unstable so loses mass through radioactive decay as neutrons are lost

Oxygen

• O16 is most abundant and O18 is heavier and the ratio is used to reconstruct the quaternary

Hydrogen

• H3 is unstable 

Oxygen and hydrogen isotopes and thie geographic composition help trace the water cycle

IREA

• Global network of stations that measure the isotopes in rainwater

As you move Northward the isotopes become lower as the water is primarily evaporated at the equator

Rainout

• decrease in isotopes as you move inland from the coast

Oxygen in the Icecores

• fluctuate with temperature
• higher temperatures mean that the isotopes are heavier (O18)

D-O

• Abrupt warming and then gradual cooling of the atmosphere
• the trigger is unknown
• After the warming there is often a heinrich event as icebergs are released into the oceans, cooling the thermohaline circulation and therefore possibly contributing to the gradual cooling

Possible hypothesis:

• solar variations
• Glacial ice feedbacks

They shopw how sensitive the climate is to small scale changes and feedbacks