Consistently Struggling Topics

Question 1

What are the 4 ways that oxygen reacts with things in the earth system in the long-term oxygen cycle?

Answer 1

1. Hydrogen and volatiles released from volcanoes
2. Iron in the oceans that comes from the crust
3. Oxidative weathering of crust
4. Methane produced from the oceans (methanotrophy)

Question 2

What are 3 ways that oxygen is prevented from reacting with other things in the earth system in the oxygen cycle?

Answer 2

1. Methane accumulation at top of atmosphere leads to hydrogen split and escape
2. Organic carbon burial in oceans prevents reaction with oxygen
3. Not reacting with the mantle at great depths

Question 3

What is methanotrophy?

Answer 3

Dead organic matter sinks, becomes methane, carbon component of CH4 recombines the whole molecule with oxygen

Question 4

How are cyanobacteria involved in producing methane in oceans that later reacts with oxygen?

Answer 4

Cyanobacteria enter bodies or organic matter which sink to ocean. Biomass of organic matter converted in to methane where it bubbles out of oceans and reacts with oxygen

Question 5

How does the ocean regulate the oxygen concentration on the long-term oxygen balance in atmosphere?

Answer 5

If oxygen declines, the ocean becomes anoxic causing the oceans to expand. This expansion causes the marine weathering rate to rise and so more phosphorus is extracted and released in to the oceans. This phosphorus fuels biosphere productivity and means that over generations of plants more carbon dioxide is taken from the atmosphere and more oxygen is produced. Forming a negative feedback

Question 6

How does the land biosphere contribute to the production of oxygen in the long term oxygen balance?

Answer 6

Increased silicate weathering means that more nutrients that assist with photosynthesis activity are available which fuels the production of oxygen in photosynthesis.

Question 7

How does the biosphere regulate oxygen in the long-term oxygen balance?

Answer 7

If oxygen gets too high then plant rubisco will stop taking in so much carbon dioxide that benefits oxygen production and instead take in oxygen that simultaneously removes oxygen from the atmosphere whilst preventing more oxygen being produced because it starts the counterproductive photosynthesis process known as photorespiration.

Question 8

What are the two ways that increased fires regulate oxygen in the long-term oxygen balance?

Answer 8

1. Burning of plants that produce oxygen
2. Material ash that is produced is washed to the oceans. Less organic carbon is buried through this process than if it were to be buried on land so it means there is more CO2 available to react with oxygen and therefore regulate its concentration.

Question 9

What are the two forms of silicate weathering in the greenhouse gases balance?

Answer 9

Carbonate Rock formation

Carbonate solution formation

Question 10

Explain carbonate solution formation

Answer 10

Ca and Mg ions from silicates react with rainwater to form a weak acid solution which then flows in to river and then to oceans. In oceans organisms use it to produce either carbonate rocks or shells.

Question 11

What is the important final step for silicate weathering?

Answer 11

the carbonate bodies are transported and locked up in the sedimentary rock layer for a long time.

Question 12

How do plants contribute to the process of silicate weathering?

Answer 12

Land plants increase the silicate weathering process either through chemical interactions or physical interactions

Question 13

How do plants chemically weather silicates?

Answer 13

Organic matter in the soil becomes organic carbon which is then converted in to CO2 by plants which then reacts with rainwater to form acid solutions that assist with dissolving the rocks

Question 14

How do plants physically weather silicates?

Answer 14

Water Recycling and bioturbation caused by root activity

Question 15

What was the overall cause of the PETM?

Answer 15

Increased GHG concentration

Question 16

What are the 3 ways that the GHG layer during the PETM increased?

Answer 16

1. Volcanic cooking of sedimentary rocks rich in GHGs
2. Volcanic destabilization of methane hydrates
3. Champagne cork effect

Question 17

What is a largely ignored feedback that could increase destabilization of methane hydrates?

Answer 17

Increased GHG and temperature could cause oceans to be warmer that would further stabilize methane hydrates that would then release more GHG. However, the rate of this feedback is believed to be insufficient

Question 18

How much did warming increase by during the PETM?

Answer 18

5 degrees Celsius over 20kyr

Question 19

How long did it take for carbon content of the atmosphere to be reduced down to suitable levels after the PETM?

Answer 19

100,000 years

Question 20

What is the Himalayan uplift hypothesis?

Answer 20

India’s collision with main continent of Asia between 90-20mya resulted in the formation of the Himalayas and the Tibetan plateau that increased the chemical and physical weathering rates

Question 21

What did France-Lanord & Derry (1997) find about the Himalayan uplift hypothesis?

Answer 21

1. Weathering rates had supposedly increased demonstrated by high ion content in river and oceans.
2. Greater burial of carbon not in carbonates and shells but in the Ganges and Brahmaputra alluvial delta

Question 22

What were the problems with the validity of France-Lanord’s and Derry’s (1997) findings about the Himalayan uplift hypothesis?

Answer 22

1. Long-term weathering rate upon secondary opinion had not increased significantly - perhaps due to colder and river conditions
2. Long-term carbon dioxide balance from other proxies did not display a reduction as a result of the increased weathering

Question 23

What are the 3 pieces of evidence for past snowball earth events?

Answer 23

Palaeomagnetism (latitude orientation, rock dating, dropstones)
BIFs: less BIFs because less oxygen being produced by plants
Cap carbonates: increased occurrence post-snowball earth events due to warm and moist envirnoments

Question 24

What was the possible cause for past Sturtian and Marinoan snowball earth events?

Answer 24

Breaking up of Rodina supercontinent in to mid latitudes increased weathering a lot meant that a lot of CO2 was removed from atmosphere and therefore a snowball earth

Question 25

What was the problem with the proposed theory for the Marinoan and Sturtian snowball earth events?

Answer 25

Donnadieu et al. (2004) ad to really stretch the data results in order to reach this conclusion