A LEVEL ENVIRONMENTAL SCIENCE: Biogeochemical Cycles
Terms in this set (29)
stores in the carbon cycle
- land animals
- plant biomass
- fossil fuels
- soil organic matter
- marine plants and animals
flows in the carbon cycle
- burial and decomposition
- absorption by animals
open and closed systems in the carbon cycle
- closed system on a global scale as only energy leaves it to enter other systems.
- on a smaller scale, the carbon cycle can be an open system e.g. forest ecosystem.
format of stored carbon
atmosphere = CO2 gas.
biosphere = organic matter in dead plants and animals and in soil.
oceans = dissolved CO2 and as calcium carbonate in shells
lithosphere = fossil fuels
residence time of reservoir
plant biomass = 9 years
atmosphere = variable
soil = 38 years
deep sea sediments = 3000 years
fossil deposits = 10 million years
oceans = 422 years
biological (organic) pump
- carbon is exchange between the oceans and the atmosphere through the actions of marine organisms.
- phytoplankton combines sunlight, water, and dissolved CO2 to produce organic material.
- carbon is decomposed and released into the ocean when the plankton dies.
physical (inorganic) pump
- surface and deep ocean waters mix by vertical currents
- this creates a more even distribution of carbon in the oceans.
carbon store distribution around the world
- high levels in mid latitudes (30
N - 40
- low levels in the Antarctic.
- countries in the mid latitudes industrialised first and release high CO2 levels into the atmosphere.
- jet streams prevent the CO2 from dispersing.
how humans impact the carbon cycle
- photosynthesis is changed by deforestation, afforestation, and sea pollution.
- aerobic respiration is changed by ploughing and increasing the amount of O2 given to decomposers.
- the top layer of the ocean mixes with the gases found in the atmosphere above it.
- atmospheric gases become dissolved in the ocean; CO2 increases in the oceans as it does in the atmosphere.
impacts of ocean acidification
- decreases alkalinity and pH in the oceans.
- animals can't develop calcium carbonate shells or bones due to the acidity.
- low pH will impact the metabolism of many organisms and their daily functions, so may not develop properly and will have problems reproducing.
- other species (plankton) will thrive in more acidic conditions.
negative feedback loop of the carbon cycle
burning fossil fuels -> increased atmospheric CO2 -> increased photosynthesis -> reduced atmospheric CO2 -> reduced temperature.
carbon capture and storage (CCS)
involves capturing carbon, usually as CO2, so that it is not released into the atmosphere.
CCS; pre-combustion technology
- fuel is converted into gaseous hydrogen and CO2.
- CO2 can be removed for storage and hydrogen can be distributed for use.
- when burnt, the hydrogen just releases water vapour but no CO2.
CCS; post-combustion technology
CO2 can be removed from exhaust gases of fossil fuel combustion using several methods;
- dissolving it in a solvent
- high pressure filtration
- adsorption processes
- cryogenic separation
- graphene adsorption
none of these methods are fully developed.
after capture, CO2 must be stored so that it can't return to the atmosphere;
- depleted aquifers
- oil/gas fields
- injected into oil reserves
- pumped into fractured basalt (may produce solid carbonate minerals).
the nitrogen cycle
how nitrogen moves between plants, animals, bacteria, the atmosphere, and soil
states of nitrogen
- to be used by different life forms, nitrogen must change states.
- nitrogen in the air is N2
- nitrates = NO3
- nitrites = NO2
- ammonium = NH4
bacteria in the nitrogen cycle
- most important part of the nitrogen cycle.
- bacteria enables nitrogen to change states
- first step in process of making nitrogen usable by plants. bacteria changes nitrogen into ammonium.
- bacteria (e.g. rhizobium or cyanobacteria) is fixed nitrogen.
- ammonium is changed into nitrates by nitrifying bacteria (e.g. nitrococcus or nitrobacter)
- nitrates are what plants can absorb.
- plants absorb nitrates from the soil into their roots.
- nitrogen is used in amino acids, nucleic acids, and chlorophyll.
industrial process that produces ammonia by bonding nitrogen and hydrogen using an iron catalyst at high temperature and pressure.
importance of the haber process
- enables farmers to produce enough food to feed 4 billion people.
- crops can't take nitrogen straight from the air.
- no atmospheric store of phosphorus, it is all in minable rock.
- once out of the rock, it can get into the ocean and build up, becoming sedimentary rock.
- if it goes into the soil, it will be taken up by plants and animals and be replaced via decomposition.
phosphorous in the body
- combines with calcium to form bone.
- has a structural role in nucleic acids and cell membranes.
- found in beer, cheese, beans, and fish.
phosphorous in household cleaners
phosphate content in household cleaners was regulated to 0.5% in july 2010
phosphorus in agriculture
phosphate is one part of NPK fertilisers. Phosphates are also found in manure.
phosphorus absorption by roots
plants cannot absorb phosphates, so have symbiotic relationships with fungi that increase surface area for phosphate absorption.