biogeochemical cycles / lab quiz 2 (modules 4-6)

biogeochemical cycle

movements of matter within and between ecosystems thru cycles of biological, geological, and chemical processes

reservoirs

components of the biogeochemical cycle that contain the matter, including air, water, and organisms

carbon cycle

movement of carbon around the biosphere among reservoir sources and sinks

7 processes of the carbon cycle

PRESBEC

• photosynthesis

• respiration

• exchange

• sedimentation

• burial

• extraction

• combustion

what are 2 fast processes of the carbon cycle

1. EXCHANGE of CO2 bw water and air

2. COMBUSTION of organic carbon that releases CO2 in air

what are 3 slow processes of the carbon cycle

1. carbon in rock

2. carbon in soil

3. carbon in fossil fuels

aerobic respiration

process by which cells convert glucose and oxygen into energy, carbon dioxide, and water

explain photosynthesis and respiration in terms of the carbon cycle (3)

1. solar energy → glucose

2. respiration releases co2

3. when organisms die → carbon in dead biomass reservoir → decomposers breakdown to return to air or respiration

explain EXCHANGE in terms of the carbon cycle (2)

• carbon released from ocean = amount of co2 diffusing into ocean water

• some enter thru photosynthesis from algae

explain SEDIMENTATION in terms of the carbon cycle (2)

• dissolved co2 combines w calcium ions to make calcium carbonate

• precipitate out of water and form limestone thru slow accumulation of sedimentation

explain BURIAL in terms of the carbon cycle (3)

• few carbon in dead reservoir buried into ocean sediments before decomposing

• fossilized

• carbon removed from food web, released thru weathering or volcanoes

steady state

When a system’s inputs equal outputs, so that the system is not changing over time

explain EXTRACTION in terms of the carbon cycle (2)

• recently, humans just remove coal oil or natural gas

• itself no impact

explain COMBUSTION in terms of the carbon cycle (2)

• (natural fires/volcanoes or human) releases CO2 in atmosphere or ash for soil

• actually has impacts

what 3 processes cause organic molecules to break down and produce co2, water, energy

combustion, respiration, and decomposition; combustion is abiotic

describe what happens if there is no human disturbance on the carbon cycle (3)

• steady state

• photosynthesis absorbs carbon, soil, released thru decomposers

• carbon into fossil fuel reservoirs balanced by slow release

why is combustion bad

warms planet

greenhouse gases

Gases in Earth’s atmosphere that trap heat near the surface

what happened after industrial revolution

carbon entering reservoirs is NOT balanced by exit of carbon anymore; move too fast into the atmosphere

effects of tree harvesting (3)

• releases co2 into atmosphere

• not enough replants → unbalanced

• incr. in atmosphere slightly balanced by incr. in ocean absorption, still bad

global warming

increase in global temperatures due to humans producing more greenhouse gases

limiting nutrient

nutrient required for the growth of an organism but available in a lower quantity than other nutrients, thereby limiting growth

nitrogen cycle

movement of nitrogen around the biosphere among reservoir sources and sinks

5 major transformations of the nitrogen cycle

1. fixation

2. nitrification

3. assimilation

4. mineralization

5. denitrification

hold nitrogen relatively shorter

nitrogen fixation

converts nitrogen gas in the atmosphere into forms of nitrogen that plants and algae can use

explain biotic fixation in terms of the nitrogen cycle (2)

• bacteria directly convert ts into ammonia then ammonium, readily used by plant and algae

• these organisms use fixed nitrogen to synthesize own tissue, secrete excess

explain abiotic fixation in terms of the nitrogen cycle (2)

• lightning or combustion processes like fire and burning fossil fuels → nitrate → precipitate down to plants

• nitrogen fixation in plant fertilizers (huge energy) → increase in crop yields esp those that need nitrogen

nitrification

conversion of ammonia into nitrite and then into nitrate

assimilation

process by which plants and algae incorporate nitrogen into their tissues

mineralization/ammonification

decomposers break down organic matter found in dead and waste and convert it into inorganic ammonium

denitrification

conversion of nitrate in a series of steps into the gases nitrous oxide + nitrogen gas, emitted into the atmosphere

leaching

process in which dissolved molecules are transported through the soil via groundwater

how do fertilizers affect nitrogen cycle (2)

• add tm n2 in atmosphere → deposited thru rainfall into ecosystem → affects species

• reduced species diversity

phosphorus cycle

movement of phosphorus around the biosphere among reservoir sources and sinks; bw land and water

3 cool facts abt phosphorus cycle

• big reservoir = collection of rocks, sediments w phosphorus

• no gas phase → limits movement from ocean to land/freshwater

• phosphorus rarely changes from phosphate

5 processes of phosphorus cycle

AMSGW

1. assimilation

2. mineralization

3. sedimentation

4. geologic uplift

5. weathering

explain ASSIMILATION in terms of the phosphorus cycle

• plants and animals absorb inorganic phosphate → organic phosphorus

explain MINERALIZATION in terms of the phosphorus cycle

• decomposers break down waste and dead bodies, turning organic phosphorus → inorganic phosphate

explain SEDIMENTATION in terms of the phosphorus cycle

• phosphorus in water is mostly insoluble and precipitates as phosphate sediments

explain GEOLOGIC UPLIFT in terms of the phosphorus cycle

geologic forces lift ocean layers, forming phosphate-rich mountains

explain WEATHERING in terms of the phosphorus cycle

• phosphate-rich mountains that weather over time, releasing phosphorus into ecosystems

how does fertilizer affect phosphorus cycle (3)

• excess phosphorus reaches water

• algal blooms consume tm oxygen

• cyanobacteria produce toxins, obv toxic to animals

dead zone

When oxygen concentrations become so low that it kills fish and other aquatic animals

impact of detergents on phosphorus cycle (2)

• ecological dead zones in waterways, causing environmental and economic damage

• bans on phosphates in detergents were introduced

how does increase in phosphorus affect plant communities (3)

• altered the Everglades ecosystem

• more cattails and a decline in sawgrass

• animals relying on sawgrass have less food + habitat

hydrologic cycle

movement of water around the biosphere among reservoir sources and sinks

largest water reservoir

oceans

smallest water reservoir

ice caps

list 5 (7) steps/processes of hydrologic cycle

1. evaporation

2. transpiration

3. condensation

4. precipitation

5. evapotranspiration, percolation, runoff

transpiration

release of water from leaves into the atmosphere during photosynthesis

evapotranspiration

combined amount of evaporation and transpiration

percolation

water absorbed into soil → percolates to ground water

runoff

Water that moves across the land surface and into streams and rivers

how does tree harvesting affect the water cycle

• reduces evapotranspiration, increases runoff and percolation

what do clear-cutting slopes do

• causes erosion and flooding by removing plants and roots that hold soil

what does paving land do

• reduces percolation, increasing runoff and evaporation

3 main human methods of altering hydrologic cycle

• diverting water for drinking, irrigation, and industrial use

producers/autotrophs

Plants, algae, and some bacteria that use the Sun’s energy to produce usable forms of energy, such as sugars

cellular respiration

process by which cells unlock the energy of chemical compounds

anaerobic respiration

• process by which cells convert glucose into energy in the absence of oxygen

aerobic respiration

for own metabolism and growth

How do plants affect oxygen levels, and what happens when forests are lost?

• Plants make more oxygen than they use during the day (photosynthesis).

• At night, they use oxygen, don’t make any

• Losing forests = less oxygen

primary productivity

rate of converting solar energy into organic compounds over a period of time

gross primary productivity

total amount of solar energy that producers in an ecosystem capture via photosynthesis over a given amount of time

net primary productivity

energy captured by producers in an ecosystem minus the energy producers respire

• NPP = GPP - R

standing crop

amount of biomass present in an ecosystem at a particular time; amount of energy in a system at a given time

productivity

measures the rate of energy production over a span of time

Why is primary productivity so low in efficiency? (3)

• 1% of sunlight becomes chemical energy

• energy lost as heat.

• Some light isn’t absorbed

How efficient is energy conversion in photosynthesis? (2)

• 0.25% of solar energy becomes NPP → 25-50% of GPP

• Photosynthesis uses lots of energy, so most is lost or used by the plant

why do aquatic systems have low efficiency in solar energy → tissue (3)

water absorbs light, esp red wave

blue light reaches deeper

deep algae evolved more pigments and migration to get light and nutrients

most productive ecosystems have what

• sunlight, water, nutrients, and warmth

4 major areas of water storage on earth

atmosphere, surface water, ocean, and groundwater

where is groundwater stiored

aquifers

2 processes that convert water into vapor

evaporation and transpiration

Describe two methods by which water on land (in lakes and rivers) returns to the oceans.

surface runoff and groundwater flow

Rain, sleet, and snow are examples of what?

precipitation

If the air contains high levels of pollutants, what effect might this have on water quality?

Pollutants brought down to contaminate rivers, lakes, streams and oceans

Which process(es) of the water cycle-precipitation, evaporation, condensation, runoff, percolation, or transpiration- might contribute to the addition of pollutants to rivers, lakes, and oceans? Why? (2)

precipitation and runoff; Precipitation carries air pollutants into water, runoff carries any pollutants into the water supply

Which of the processes associated with the water cycle might be responsible for helping to clean or filter the water? (3)

absorption and transpiration by plants and percolation

The water cycle is a closed system, meaning no water enters from beyond the system nor leaves the system. What does that say about the importance of keeping the water on Earth free from
pollution? (3)

pollution @ one point affects other points

Percolation and plant use are limited to little clean water.

runoff carries pollution.

Name two ways that carbon(usually in the form of CO2
) enters the atmosphere.

1. auto factory emissions from combustion

2. respiration

What would happen if decomposition did not occur? (3)

• carbon would not recycle into the atmosphere

• less co2 for photosynthesis

• wastes and dead organisms pile

List four materials that contain this stored carbon.

a.) coal, oil, peat, and natural gas

What is the collective term for these four materials?

fossil fuels

How do humans use the materials in the carbon sink?

burn for energy (combustion)

Nearly half of the electricity in the US is generated by the combustion of …

coal

How does our use of these carbon stores affect the amount of CO2
in the atmosphere?

release stored carbon into atmosphere → more co2 in atmosphere

three types of bacteria involved in the nitrogen cycle.

nitrogen fixing bacteria, nitrifying bacteria, and denitrifying bacteria

2 ways N2 gas removed from the atmosphere

Nitrogen fixation by N-fixing bacteria in the soil and in the root nodules of legumes

By what process are animal wastes and dead organisms converted to other nitrogen-containing compounds?

conversion to ammonia and ammonium compounds; ammonification

What is the only form of nitrogen that nonlegume plants can take in and use?

nitrates

What do the denitrifying bacteria do during the denitrifying process?

convert nitrates and nitrites back into N2 and N2O

If the number of nitrifying bacteria decreased, what effect would this have on the nitrogen cycle and what type of compounds would accumulate as a result (3)

• unbalanced cycle

• ammonia accumulates

• no return to atmosphere

In order to continually use the same area of land for agriculture, some farmers apply artificial fertilizers to improve the level of nitrates in the soil. An alternative to intensive use of artificial fertilizer is to plow the roots of the leguminous plants back into the soil and leave the area unplanted for a season. Why would a farmer plow this type of plant roots back into the soil and what would be the benefit of turning over the soil and leaving the old plant roots? (2)

• Leguminous plants contain root nodules → convert atmospheric nitrogen into nitrates for use by plants

• leaving the old roots in the soil → nitrates replaced

phosphorus is typically found in (3)

• solid rock

• phosphates in soil

• organic compounds

2 ways phosphorus returns to soil

• decomposition

• waste

how does phosphorus in soil move into rock

sedimentation

how does phosphorus become available again after it becomes stored in rock

weathering

2 pathways phosphorus can take after going in soil

• plant uptake

• leaching

2 actions phosphorus can do in plants

• energy production

• growth and development