Flashcards in 4. Carbon Cycle Deck (22):
What does air monitoring stations do?
measure concentrations of carbon dioxide, methane and other gases
What do carbon dioxide concentrations show annually?
- drop: May - October
- rise: October - May
Explain why carbon dioxide levels show an annual fluctuation?
drop: excess of photosynthesis over cell respiration globally
rise: excess of cell respiration of photosynthesis globally
changes follow northern hemisphere seasons because:
- area of lang is greater in northern hemisphere
- and carbon dioxide concentrations are greater on land than in sea
Apart from annual fluctuations in carbon dioxide concentrations, what other trends are there?
rising trend in atmospheric carbon dioxide concentrations due to human activities
Is it possible to measure global carbon fluxes precisely?
no, but scientists have produced estimates based on many measurements in natural ecosystems and in mesocosms
What are global fluxes of carbon measured in?
Name the 6 process that make a significant difference to global atmospheric carbon dioxide levels each year.
2 cell respiration
3 ocean uptake
4 ocean loss
5 deforestation and land use changes
6 combustion of fossil fuels
ocean uptake = CO2 from atmosphere dissolving in water
What is the flux produced by photosynthesis in gigatonnes per year?
-120 (minus 120, photosynthesis takes 120 gigatonnes of carbon dioxide out of the atmosphere per year)
What is the flux produced by cell respiration in gigatonnes per year?
What is the flux produced by ocean uptake in gigatonnes per year?
What is the flux produced by ocean loss in gigatonnes per year?
What is the flux produced by deforestation and land use changes in gigatonnes per year?
What is the flux produced by combustion of fossil fuels in gigatonnes per year?
What does limestone mainly consist of?
calcium carbonate (CaCO3)
What can limestone rock often contain?
fossils such as mollusc shells and skeletons of hard coral
What is significant about fossilised organisms such as mollusc shells and skeletons of hard coral?
- they abosorb calcium and carbonate ions and secrete them as calcium carbonate:
- marine molluscs die > the shells fall to the sea bed > becomes part of limestone rock > skeletons of hard corals accumulate over time > gradually builds a coral reef (which consists of limestone)
"Huge amounts of .... are locked up in limestone." Fill in blanks.
How can carbon in limestone be released?
if the limestone reacts with acid
How can rainwater cause limestone to break down?
- rainwater contains carbonic acid (H2CO3)
- acid breaks down limestone
carbonic acid + calcium carbonate --> calcium ions + hyrdogen carbonate ions
Name the 2 types of fossil fuel formation.
1 peat and coal
2 oil and gas
How are fossil fuels formed with peat and coal?
- saprotrophs cannot break down organic matter in acidic and anaerobic conditions
- these conditions are found in bogs and swamps
- partially decomposed plant matter accumulates to form thick deposits called peat
- in past geological eras, peat was crushed to form coal