1. Environmental Chemistry
Feb. 20, 2018

2. Origins Create the universe Create the elements Create the Earth
Form the atmosphere and oceans

3. Create the Earth
Accretion – gravity-driven process by which smaller objects collide and combine to form a larger object
Interior heats and exterior cools. Molten interior results in movement, e.g., plate tectonics, which allows substances to segregate based on properties
What characteristics differentiate substances (both elements and compounds)?
Density
Volatility/Phase
Solubility
Organic/Inorganic
Mineral?

5. ‘Spheres’ of the Earth system

6. Box models and steady-state
𝑑𝑉 𝑑𝑡 =𝐼𝑛𝑓𝑙𝑜𝑤+𝑂𝑢𝑡𝑓𝑙𝑜𝑤
At steady state:
𝑑𝑉 𝑑𝑡 =𝐼𝑛𝑓𝑙𝑜𝑤+𝑂𝑢𝑡𝑓𝑙𝑜𝑤=0
𝐼𝑛𝑓𝑙𝑜𝑤=−𝑂𝑢𝑡𝑓𝑙𝑜𝑤

7. How did the spheres evolve?
Two essential ingredients:
Liquid water
Atmosphere

8. Questions Has there always been liquid water?
What are the sources of water?
Has water been gained/lost over earth history?

9. Water reservoirs Little loss to space
For liquid H2O, T must be 0˚C ˚C
Figure 09-05
How to Build a Habitable Planet Copyright © Princeton University Press 2012

10. Energy balance

11. What maintains temperature?
Feedbacks on CO2 concentration
Weathering
3 H2O + 2 CO2 + CaSiO3  Ca HCO3- + H4SiO4
Precipitation
Ca HCO3-  CaCO3 + H2O + CO2 (foraminifera)
H4SiO4  SiO2 + 2 H2O (diatoms)
Mantle
CaCO3 + SiO2  CaSiO3 + CO2
wollastonite

12. Carbonate-silicate cycle
Timescale = 105 – 107 yrs
J. F. Kasting, Science Spectra, 1995

13. Feedback on CO2
Figure 09-11
How to Build a Habitable Planet Copyright © Princeton University Press 2012