Biogeochemical cycling

Question 1

what is biogeochemical cycling?

Answer 1

the distribution of a substance between different compartments of an environmental system involving chemical, physical and biological, geological processes

Question 2

define a biogeochemical cycle?

Answer 2

a conceptual model of the processes involved in the biogeochemical cycling of given substance, this may be a model of global, regional or local scale

Question 3

what is the significance of biogeochemical cycling?

Answer 3

geochemical cycles turned what we see now as what it is, so we want to see how this earth system has been formed

Question 4

Describe how did co2 in the atmosphere gradually decrease by biogeochemical cycling?

Answer 4

more and more algae formed over time, so oceans became more oxygenated so oxygenated started to accumulate at the atmosphere and co2 decreases

Question 5

define a reservoir

Answer 5

a specific aggregate entity within a system; biosphere; lithosphere; atmosphere

Question 6

define a burden

Answer 6

the mass of a substance in a specific reservoir or system = concentration x volume

Question 7

define a source

Answer 7

a flux of material into a reservoir

Question 8

define a sink

Answer 8

a flux of material out of a reservoir; often assumed to be proportional to the content of the reservoir

Question 9

define a budget

Answer 9

a balance sheet of all sources and sinks of a reservoir

Question 10

define a cycle

Answer 10

a system consisting of 2 or more connected reservoirs, where a large part of the material is transferred through the system

Question 11

define mixing time

Answer 11

the time taken for a given substance to achieve uniform distribution throughout the whole of a given reservoir

Question 12

define horizontal mixing time

Answer 12

time taken for complete mixing to occur in a horizontal sense

Question 13

define vertical mixing time

Answer 13

time taken for complete mixing to occur in a vertical sense

Question 14

define overall mixing time

Answer 14

time taken for complete mixing to occur in both a horizontal and vertical sense which is equivalent to whichever is the longest and vertical times

Question 15

what is the order in which mixing time increases in the atmosphere?

Answer 15

boundary layer
troposphere
stratosphere

Question 16

what influences mixing time? (2)

Answer 16

size (mass or volume)

fluidity/viscosity

Question 17

What type of compartment will have longer mixing times?

Answer 17

large and viscous

Question 18

What type of compartment will have shorter mixing times?

Answer 18

small and fluid

Question 19

what does a short mixing time mean?

Answer 19

changes in concentrations arising from changes in inputs to the compartment will occur pretty quickly |(why the atmosphere is most responsive to anthropogenic change)

Question 20

What defines lifetime/residence time?

Answer 20

the average time taken for a substance to stay in a reservoir before it is removed

Question 21

what does t = A/R mean?

Answer 21

the lifetime equals the amount of the substance in the reservoir divided by teh rate of addition or removal of the substance from that reservoir

Question 22

what does A represent in t = A/R?

Answer 22

The burden e.g mass of a substance in a reservoir

Question 23

what does S and R represent and when are they equal?

Answer 23

S = sources
R = sinks
they are equal at a steady state

Question 24

what does it mean if a substance has a long lifetime?

Answer 24

they will show little spatial and vertical variability as they lifetimes exceed both the vertical and horizontal mixing times of the troposphere

Question 25

what are environmental transfer processes?

Answer 25

- processes via which a substance is transferred between 2 compartments

Question 26

Name some examples of environmental transfer processes

Answer 26

- riverine transport of dissolved and suspended material from land to oceans - transport of dissolved and suspended material from atmosphere to land and oceans via precipitation - transport of gas and particles from the land/ocean to atmosphere

Question 27

define flux

Answer 27

defined as the rate at which a substance is transferred between compartments (rate at which a transfer mechanism occurs)

Question 28

what is dry deposition?

Answer 28

the direct transfer of gases and particles to the land or water surface i.e a transfer mechanisms

Question 29

what is wet deposition?

Answer 29

the removal from the atmosphere of substances dissolved in precipitation

Question 30

what is the driving force between all the earth's sphere (lithosphere, biosphere, hydrosphere, atmosphere)?

Answer 30

solar energy

Question 31

which sphere has the shortest mixing times but also most fluid of all?

Answer 31

atmosphere

Question 32

what is the largest gas in the atmosphere?

Answer 32

nitrogen, 78.08%

Question 33

describe the differences in mixing times for the different layers of the atmosphere?

Answer 33

- boundary layer is only s few hours - troposphere is only a few weeks - stratosphere is only a year

Question 34

describe the lithosphere?

Answer 34

envelope of the earth where soils occur, an interface between the earth, atmosphere and biosphere

Question 35

describe the mixing time of the litosphere?

Answer 35

longgg

Question 36

name some different types of weathering

Answer 36

- physical - chemical - oxidation - dissolution - biological

Question 37

what are some consequences of weathering?

Answer 37

- soil formation - ions loss to the oceans - soils can be suspended in water and carries away to oceans

Question 38

whats the difference between chemical and physical weathering?

Answer 38

- chemical; break down of rocks by chemical reactions by water - physical; break down of rocks into smaller processes by physical means such as ice, wind

Question 39

name 4 processes associated with the hydrosphere?

Answer 39

- evaporation/precipitation - sedimentation - groundwater and river discharge - ocean circulation

Question 40

describe the ocean as a reservoir

Answer 40

- very large - not as fluid as atmosphere - mixing time is longer - respond more slowly to anthropogenic change and sea pollution tends to be more localised than air pollution

Question 41

describe the nitrogen cycle

Answer 41

- biological fixation of nitrogen from the atmosphere where its taken up by plants - incorporated into organic molecules - when plants/organisms die they go through soil processes and release particles into the atmosphere by decomposition

Question 42

how can anthropogenic influences change the water cycle?

Answer 42

- dam building - re distribution of precipitation - groundwater use - sea level rise and glacial meting

Question 43

how can dam building affect the water cycle?

Answer 43

- water transport will be reduced and large areas flooded, more evaporation from local reservoir which can have an effect on the local climate

Question 44

what are the impacts of anthropogenic changes to the water cycle?

Answer 44

- air pollution - acid rain - eutrophication - forest fertilization

Question 45

What is phosphorus cycling|?

Answer 45

Phosphate in rocks enters the soil, the phosphate is absorbed by plans, the phosphates pass from organisms to organism in a food chain or food web