Biogeochemical & Carbon Cycles

• Ecosystems maintain biochemical balance through biogeochemical cycles.
• Water cycle is a biogeochemical cycle example.

Biogeochemical Cycle

• It is the transformation and circulation of a chemical element between the lithosphere, hydrosphere, atmosphere, and biosphere.

Carbon Cycle

• Life on Earth is based on carbon chemistry.
• Carbon molecules are present in vital processes.
• The quantity of carbon on Earth remains constant.
• The form of carbon depend on connecting chemical elements.
• Carbon exists in the biosphere, lithosphere, hydrosphere, and atmosphere.
• Carbon is present in proteins and organic molecules of living organisms.
• Carbon is in carbonate rocks and fossil fuels in the lithosphere.
• The hydrosphere contains dissolved carbon dioxide, leading to bicarbonate and carbonate ions' formation.
• The atmosphere holds carbon dioxide and methane, greenhouse gases.
• Carbon transforms through photosynthesis, respiration, combustion, feeding, decomposition, dissolution, carbonate rock formation, volcanism, and methanation.

Nitrogen Cycle

• Living organisms need nitrogen to produce proteins.
• Most organisms cannot directly use atmospheric nitrogen, which is 78% dinitrogen(N₂).
• The nitrogen cycle converts gaseous nitrogen into a form that plants can use, then animals.
• The hydrosphere behaves similarly to the lithosphere

Nitrogen Reservoirs

• Nitrogen exists in proteins within living beings, formed from amino acids like alanine.
• The lithosphere and hydrosphere contains nitrogen in ammonia, ammonium, nitrites, and nitrates.
• Nitrogen mainly occurs as diatomic gas in the atmosphere.
• Nitrogen cycles through fixation, nitrification, assimilation, food chains, decomposition, and denitrification.
• Bacteria fixed in the soil convert nitrogen to ammonium.
• Special bacteria performs nitrification, converting ammonium to nitrites.
• Plants assimilate nitrates into organic nitrogen.
• Decomposition converts organic nitrogen to ammonium.
• Bacteria cause denitrification converting nitrates to N₂.
• Agricultural fertilizers are sources of ammonium and nitrates.

Phosphorus Cycle

• DNA requires phosphorus.
• Bones, teeth, and animal shells need phosphorus.
• Phosphorus cycles from one envelope to another.
• Phosphorus follows aquatic and terrestrial cycles, with phytoplankton introducing dissolved phosphates.

Phosphorus Reservoirs.

• Phosphorus is present in proteins and DNA in the biosphere.
• The lithosphere and hydrosphere contain phosphorus in rocks, minerals, and phosphates.
• The atmosphere contains hardly any phosphorus.
• Phosphates come from wind and rain erosion from rocks into sediments.

Soil Horizons

• Soil horizons are horizontal layers in the soil distinguished by composition.
• Main horizons are O, A, B, C, and R, differing by their physical properties and composition.
• The O horizon, is a superfical layer, contains humus and decaying organic matter.
• The A horizon is arable land and is cultivatable, contains little mineral but much organic matter
• The B horizon, is a Subsoil, contains very little organic matter, but a lot of minerals
• The C horizon is fragment rock, contains debris from erosion but barely any organic material
• The R horizon, is Bedrock, unaltered and serving as the foundation.
• A quality soil takes biological and geological processes that take thousands of years

Soil Reactivity

• Soils are dynamic environments of chemical and biological reactions.
• Humidity, pH, and mineral content regulate a soil's chemical, biological activity, and fertility.

Soil Characteristics

• Sandy soils are permeable, dry, and less fertile.
• Clayey soils are less permeable, retain moisture, and fertile.
• Loamy soils are somewhat permeable, store moisture, and are quite fertile.
• Humiferous soils' moderate permeability creates sufficient humidity and high fertility.

Optimal Soil Conditions

• Soil pH between 6.5 and 7.5 ensures fertility.
• A good composition is organic with diverse minerals and contains a lot of water
• A good soil retains enough water to conserve humidity
• A good soil hosts bacterial communities to recycle chemicals

Soil Buffer Capacity

• pH influences on a soil's chemical and biological activity must be factored in.
• Plants grow best in neutral soil with a pH of 6.5 to 7.5.
• Acidic or alkaline soils alter a chemical element's bioavailability which reduces plant growth.
• Essential and toxic minerals become inaccessable to plants
• Soils compensate for acidification with neutralization.
• Soil buffer capacity is the ability to maintain its pH despite acidic or alkaline additions.

Factors Accelerating Soil Acidification

• Acid rain and fertilizer use increase soil acidity
• Intensive agriculture removes biomass that would have neutralized the soil.

Soil Types Buffer Capacities

• Sandy soils are fragile and require carefully managed fertilizer use.
• Argillaceous and Humiferous soils are less sensitive and can handle intensive agriculture
• Limoneux soils are somewhere in the middle

Green Fertilizers

• Green fertilizers enrich humus in the O horizon and boost soil porosity.
• They also make produced nitrites less prone to erosion, which increases biological activity.

Permafrost

• Permafrost stays frozen, and an area is classified as permafrost when it maintains a sub-zero temperature
• Nearly 50% of Canada is permafrost
• Permafrost occurs in polar regions and high altitudes and can vary in thickness.
• Permafrost inhibits agriculture and makes construction hard.
• Vegetation is like tundra, with very thin soil

Permafrost Reservoirs

• Permafrost serves as a hefty reservoir of carbon
• It traps double the carbon in the atmosphere

Ores and Minerals

• Metals are required for modern technology
• Minerals mixed with other substances need to be extracted from the lithosphere by transforming the ore.
• Transforming ore requires a lot of energy

Mineral

• Solid substance in the lithosphere with defined physical and chemical properties.

Ore

• A rock containing good mineral concentrations for mining.

Mining Impacts

• Mining has environmental consequences.
• Mining companies need to decontaminate work sites.
• Liquid waste pollutes water and soil is contamininated with runoff.
• Gas emissions, deforestation, and habitat contamination also occur.

Consequences of Thawing Permafrost

• Global warming impact is relevant.
• Infrastructure becomes unstable.
• Infrastructure suffers after thawing
• Thawing results in mud slides and erosion

CO2 and Methane Release

• Greenhouse gas comes as a result of thawing
• As bacteria eat organic material it releases gases.

Perturbing Biogeochemical Cycles

• Human activities disrupt cycles.
• Agriculture and mining add carbon, nitrogen, and phosphorus.
• Massive CO2 emissions trap extra radiation and melt glaciers

Soil Contamination

• Human actvities cause soil disruption.
• Soil contamination alters chemical equilibrium, like pesticides and fertilizers

Soil Depletion

• Depletion reduces agricultural activity.
• Agricultural practices inhibit replacement, losing nutrients and fertility.