Water and Carbon Cycle Key terms:

Carbon

One of the most chemically versatile of all the elements. Forms more compounds than any other element. It is found in all life forms in addition to sedimentary rocks, diamonds, graphite, coal and petroleum (oil and gas).

The carbon cycle

The complex process carbon undergoes as it is transformed from organic carbon (the form found in living organisms such as plants and trees) to inorganic carbon and back again.

Carbon

One of the most chemically versatile of all the elements. Forms more compounds than any other element. It is found in all life forms in addition to sedimentary rocks, diamonds, graphite, coal and petroleum (oil and gas).

The carbon cycle

The complex process carbon undergoes as it is transformed from organic carbon (the form found in living organisms such as plants and trees) to inorganic carbon and back again.

Carbon Dioxide (CO2)

A gas found in the atmosphere, soils and oceans.

Methane (CH4)

A gas found in the atmosphere, soils and oceans and sedimentary rocks.

Calcium Carbonate (CaCO3)

A solid compound found in calcareous rocks, oceans and in the skeletons and shells of ocean creatures.

Hydrocarbons

Solids, liquids or gases usually found in sedimentary rocks.

Bio-molecules

Complex carbon compounds produced in living things. Proteins, carbohydrates, fats & oils and DNA are examples.

Gigatonne

The most common unit used to measure carbon. 1 is equivalent to a one billion tonnes.

Transfer/flux

Measure in gigatonnes/year (Gtc/yr). The movement of carbon between stores.

Anthropogenic CO2

Carbon dioxide generated by human activity

Biosphere

The total sum of all living matter. This can be divided in the terrestrial biosphere (3,170 GtC) and the oceanic biosphere.

Carbon sequestration

The capture of carbon dioxide from the atmosphere or capturing anthropogenic (human) CO2 from large-scale stationary sources like power plants before it is released to the atmosphere. Once captured, the CO2 gas (or carbon portion of the CO2) is put into long-term storage.

Carbon sink

A store of carbon that absorbs more carbon than it releases.

Greenhouse Gases (GHGs)

Any gaseous compound in the atmosphere that is capable of absorbing infrared radiation, thereby trapping and holding heat in the atmosphere. prevents outgoing terrestrial infrared radiation from escaping to space

Lithosphere

A rigid layer made up of the uppermost part of the mantle and the crust. Carbon is distributed between the marine sediments (100 million GtC), soil organic matter (1500 GtC), fossil fuel deposits (4,100 GtC) and peat (250 GtC).

Weathering

The breaking down of rocks and other materials on the Earth's surface by biological, chemical or mechanical processes.

Euphotic Zone

Upper layer of a body of water through which sunlight can penetrate and support photosynthesis. Contains approximately 900 GtC of carbon.

Twilight Zone

A layer of water under the sunlight zone extends to 3000 feet compliantly dark no light light very high pressure near freezing temps no plant life. Contains approximately 37,100 GtC of carbon.

Terrestrial biosphere: Living vegetation

19% of the carbon in the Earth's biosphere is stored in plants (20% of this is stored in the Amazon rainforest). Much of this carbon is stored directly in the tissue of plants.

Terrestrial biosphere: Plant litter

This is defined as the fresh, undecomposed and easily recognisable (by species and type) plant debris. This can be anything from leaves, cones, needles, twigs, bark, seeds, nuts etc. Leaf tissues account for 70% of the debris in forests.

Terrestrial biosphere: soil humus

This originates from litter decomposition. It is a thick brown or black substance that remains after most organic litter has decomposed. It gets dispersed through the soil by soil organisms such as earthworms.

Organic carbon

Relating mainly to carbon compounds derived from biological sources. Also refers to carbon sources other than simple carbonates and carbon dioxide, such as hydrocarbons.

Inorganic carbon

Carbon extracted from ores and minerals e.g carbon dioxide, carbonic acid, bicarbonate anion, and carbonate.

Terrestrial biosphere: Peat

An accumulation of partially decayed vegetation or organic matter that is unique to natural areas called peatlands or mires. It covers 4 million km2 or 3% of the land and freshwater surface of the planet; they occur in all continents. It is estimated that they store 250 GtC worldwide.

Terrestrial biosphere: Animals

play a small role in the biosphere. important in the generation of movement in the carbon through the carbon cycle.

Pool

Another name for a carbon store

The Atmosphere

Carbon makes up approximately 0.04% but this concentration is higher than it has been since records began. It plays a vital role in regulating the Earth's temperature and the carbon levels are measured from Mauna Loa Observatory (MLO).

The Keeling Curve

A graph made over the span of 50 years that shows the increase of carbon dioxide concentrations in the atmosphere.

The Geological Component of the Carbon Cycle

Where the carbon cycle interacts with the rock cycle in the processes of weathering, burial, subduction and volcanic eruptions.

Photosynthesis

Energy from sunlight used to combine carbon dioxide from the atmosphere with water to form carbohydrates. These carbohydrates store energy. Oxygen is a by-product that is released into the atmosphere.

Respiration

The process by which cells break down simple food molecules to release the energy they contain.

Decomposition

A chemical reaction that breaks down compounds into simpler products. The process of decomposition is carried out by decomposers.

Oceanic carbon pump

The oceans are called this because they cycle carbon from the deep waters to surface waters and the atmosphere through the process of vertical deep mixing.

Vertical deep mixing

The most important movement of CO2 in the oceans. The process by which warm water from the tropics is carried to the polar regions, where it sinks and takes the CO2 with it as it cools. When it warms again, the water rises and releases CO2 to the atmosphere.

Carbon Pump

Any part of the carbon cycle that moves carbon to the next part of the cycle.

Biological carbon pump

The action of organisms moving carbon in one direction

Combustion

When any organic material is reacted (burned) in the presence of carbon dioxide, water and energy. The organic material can be any vegetation or fossil fuel.

Biomass combustion

The burning of living and dead vegetation. It includes human-induced burning as well as naturally occurring fires.

Hydrocarbon extraction

The removal and isolation of target compound(s) from a solution or solid matrix.

Anoxic

Oxygen free

Deforestation

The removal of trees. This is driven by the need for extra agricultural land and logging. 13 million ha (approximately) - an area the size of Greece - of the world's forest are being cut down every year.

Afforestation

The planting of trees.

Urban growth

The rate of increase of urban populations. The urban population is expected to reach 60% by 2030. Urban areas are growing at a rate of 1.3 million people every week.

Geological sequestration

Co2 is captured at its source (e.g. power plants) and then injected in liquid form into stores underground. These could be depleted gas reservoirs, thin, uneconomic coal seams, deep salt formations and deep ocean. This is still in its experimental age.

Terrestrial or biologic sequestration

This involves the use of plants to capture CO2 from the atmosphere and then to store it as carbon in the stems and roots of the plants as well as in the soil

Carbon budget

The balance of the carbon exchanges between carbon sinks and sources.

Ocean acidification

About 30% of the CO2 that has been released into the atmosphere has diffused into the ocean through direct chemical exchange. Dissolving CO2 in the ocean creates carbonic acid. This makes the slightly alkaline ocean become a little less alkaline. Since 1750, the pH of the ocean's surface has dropped by 0.1, a 30% change in acidity.

Enhanced greenhouse effect

The impact on the climate from the additional heat retained due to the increased amounts of CO2 and other greenhouse gases that humans have released into the Earth's atmosphere since the industrial revolution.

Radiative forcing

The difference between the Earth's incoming solar radiation absorbed by the Earth and energy radiated back to space.

Soil organic carbon (SOC)

The organic constituents in the soil: tissues from dead plants and animals, products produced as these decompose and the soil microbial biomass.

Carbon capture and sequestration (CCS)

A technology that can capture up to 90% of CO2 emissions produced from the use of fossil fuels in electricity generation and industrial processes, preventing the CO2 from entering the atmosphere. The CCS chain consists of capture, transporting and storing.

system

a set of interrelated components working together towards a process

input

the addition of matter and/or energy into a system

Flow/transfer

a form of linkage between one store/component and another that involves movement of energy or mass

Store/component

part of the system where energy/mass is stored or transformed

output

the results of the processes within a system

isolated systems

no interactions with anything outside of the system boundary. no input or output of energy or matter. very rare in nature and normally occur in labs.

closed systems

transfers of energy both into and beyond the system boundary but not transfer of matter

open systems

where matter and energy can be transferred from the system across the boundary into the surrounding environment (most ecosystems)

cascading systems

an open system that forms part of a chain

example of cascading system

the earth’s 4 major subsystems (atmosphere, lithosphere, hydrosphere, and biosphere)

positive feedback

where the effects of an action are amplified or multiplied by subsequent knock-on or secondary effects

negative feedback

where the effects of an action are nullified by its subsequent knock-on effects

example of positive feedback

increase in carbon dioxide

example of negative feedback

increased use of fossil fuels

dynamic equilibrium

where there is a balance between the inputs and outputs

cryospheric process

process affecting the total mass of ice at any scale from local patches of frozen ground to global ice amounts. This includes accumulation (build-up of ice mass) and ablation (the loss of ice mass)

what controls cryospheric processes

global climate over long term scales

cryospheric water

water locked up on the Earth’s surface as ice: sea ice, ice sheets, ice caps, alpine glaciers, and permafrost.

atmospheric water

water found in the atmosphere mainly water vapour with some liquid water (cloud and rain droplets) and ice crystals

discharge

the amount of water in a river flowing past a particular point expressed as m³s^-1 (cumecs)

hydrosphere

discontinuous layer of water at or near the Earth’s surface. includes all liquid and frozen surface waters, groundwater held in soil and rock and atmospheric water vapour

oceanic water

water contained in the Earth’s oceans and seas but not including inland seas (like the Caspian Sea). makes up 97% of all water

terrestrial water

groundwater, soil moisture, lakes, wetlands, rivers, and biological water

biological water

the water stored in all the biomass

3 forms of water

solid, liquid, gas

evaporation

solar radiation hits the surface of water or land and causes liquid water to change state from a liquid to a gas (water vapour)

factors affecting evaporation rate

• amount of solar energy

• availability of water

• humidity of air (closer air is to saturation point the slower evaporation rate)

• temp of air (warmer can hold more water vapour)

condensation

as air cools is can’t hold as much water vapour, when it gets to a cool temp where it is saturated it is at dew point temp. excess water in the air will then be converted to liquid water. the water molecules need something to condense on (tiny particles like smoke, salt dust). water vapour changes to liquid water

permafrost

formed when air temp are so low they freeze any soil and groundwater present

drainage basin

this is an area of land drained by a river and its tributaries. includes water found on the surface (in soil and near-surface geology)

evapotranspiration

the total output of water from the drainage basin directly back into the atmosphere

groundwater flow

the slow movement of water through underlying rocks

infiltration

downward movement of water from the surface into soil

interception store

the precipitation that falls on the vegetation surfaces (canopy) or human-made cover and it’s temporarily stored on these surfaces. intercepted water either can be evaporated directly to the atmosphere, absorbed by the canopy surfaces or ultimately transmitted to the ground surface

overland flow

tendency of water to flow horizontally across land surfaces when rainfall has exceeded the infiltration capacity of the soil and all surface stores are full to overflowing

percolation

downward movement of water within the rock under the soil surface. rates vary depending on the nature of the rock

run-off

all the water that enters a river channel and eventually flows out of the drainage basin

saturated

this applies to any water store that has reached it maximum capacity

stemflow

the portion of precipitation intercepted by the canopy that reaches the ground by flowing down stems, stalks, or tree boles (trunk)

storm and rainfall event

an individual storm is defined as a rainfall period separated by dry intervals of at least 24 hours and an individual rainfall event is defined as a rainfall period separated by dry intervals of at least 4 hours (Hamilton and Rowe)

throughfall

the portion of the precipitation that reaches the ground directly through gaps in the vegetation canopy and drips from leaves, twigs and stems. This occurs when the canopy-surface rainwater storage exceeds its storage capacity

throughflow

movement of water downslope through the subsoil under the influence of gravity. it is particularly effective when underlying permeable rock prevents further downward movement

transpiration

the loss of water from vegetation through pores (stomata) on their surfaces

water balance

balance between inputs (precipitation) and outputs (run-off, evapotranspiration, soil and groundwater storage) in a drainage basin

bankfull

maximum discharge that a river channel is capable of carrying without flooding

base flow

the normal day-to-day discharge of the river and is the consequence of slow moving soil throughflow and groundwater seeping into the river channel

lag time

time between the peak rainfall and peak discharge

peak discharge

point on a flood hydrograph when river discharge is at its greatest

storm flow

discharge resulting from storm precipitation involving both overland flow, throughflow and groundwater flow