Biogeochemical Cycle

• Phosphorus Cycle

  The biogeochemical cycle that describes the movement of phosphorus through the lithosphere, hydrosphere and biosphere
• Phosphorus-based compounds are usually solids at the typical ranges of temperature and pressure found on earth
• Phosphorus

  • Essential for plant and animal growth, as well as the health of microbes inhabiting the soil
  • Gradually depleted from the soil over time
• Main biological function of phosphorus

  Required for the formation of nucleotides, which comprise DNA and RNA molecules
• The phosphorus cycle is an extremely slow process, as various weather conditions (e.g. rain and erosion) help to wash the phosphorus found in rocks into the soil
• Phosphorus Cycle Steps

  1. Weathering - Extraction of phosphorus from rocks by weathering, resulting in phosphorus being washed into the soil.2. Absorption by plants and animals - Plants, fungi, and microorganisms absorb phosphorus from the soil and water

  3. Return to the environment via decomposition - When plants and animals die, decomposition returns phosphorus back to the environment via the water or soil
• Human impact on the phosphorus cycle

  • Significant impact due to the use of fertilizer, the distribution of food products, and artificial eutrophication
  • Fertilizers containing phosphorus add to the phosphorus levels in the soil and are particularly detrimental when such products are washed into local aquatic ecosystems
• Nitrogen


  An invisible gas that composes the majority of Earth's atmosphere. It is a vital element of all known forms of life. It is considered an abundant gas, however, living organisms cannot consume it in its gaseous form.
• Nitrogen

  • Usable nitrogen in the natural world came from bacteria. Rhizobium and free-living bacteria in the genus Azotobacter are some of these bacteria.
• Nitrogen Cycle

  1. Nitrogen Fixation (N2 to NH3 or NO3)

  2. Nitrification (NH3 to NO3)

  3. Assimilation (Incorporation of NH3 and NO3 into biological tissues)

  4. Ammonification (organic nitrogen compounds to NH3)

  5. Denitrification (NO3 to N2)
• Rhizobium - bacteria in roots of legumes that provides nitrogen
• How do we use nitrogen? Through the chemical and biological processes that form the nitrogen cycle.
• Effects of Human Activities on Nitrogen Cycle: Adding nitrous oxide to the atmosphere from vehicles and factories which contribute to acid rain. Contaminating ground water from nitrate ions in inorganic fertilizers.
• Haber-Bosch process = production of fertilizers by combining nitrogen and hydrogen to synthesize ammonia.
• Humans overcame the limits on crop productivity by fixing atmospheric nitrogen with fertilizers
• Effects of Human Activities on Nitrogen Cycle: Increases emissions of greenhouse gases and smog. Acidifies water and soils. Moves nitrogen into terrestrial systems and oceans. Reduces diversity of plants adapted to low-nitrogen soils. Changes estuaries and coastal ecosystems and fisheries.
• Carbon Cycle

  The process where carbon compounds are interchanged among the biosphere, geosphere, hydrosphere, and atmosphere of the earth
• Simplified Steps of Carbon Cycle

  1. Carbon present in the atmosphere is absorbed by plants for photosynthesis

  2. Plants are consumed by animals and carbon gets bio accumulated into their bodies

  3. Upon decomposition, these plants and animals release carbon into the atmosphere

  4. Some of these carbon becomes fossil fuels over time

  5. Fossil fuels are used for human activities, releasing more carbon into the atmosphere
• The Wealth of Nations was written in 1776
• Rational (in classical economic theory)

  Economic agents are able to consider the outcome of their choices and recognise the net benefits of each one
• Producers act rationally by


  Selling goods/services in a way that maximises their profits
• Workers act rationally by

  Balancing welfare at work with consideration of both pay and benefits
• Governments act rationally by

  Placing the interests of the people they serve first in order to maximise their welfare
• Rationality in classical economic theory is a flawed assumption as people usually don't act rationally
• Marginal utility

  The additional utility (satisfaction) gained from the consumption of an additional product
• If you add up marginal utility for each unit you get total utility
• Photosynthesis

  A process used by plants and other organisms to convert light energy into chemical energy. Reactants: Carbon dioxide (CO2) + Water (H2O) + Light energy. Products: Glucose (C6H12O6) + Oxygen (O2)
• Water

  The liquid that allows life on Earth to exist. Water changes our world and practically every aspect of our existence as it cycles from the air to the land to the sea and back to the air again, repeating the cycle.
• Respiration

  A biological process that occurs in all living organisms, including plants, animals, and microorganisms. Reactants: Glucose (C6H12O6) + Oxygen (O2). Products: Carbon dioxide (CO2) + Water (H2O) + Energy (in the form of ATP)
• All Living Things

  • Need Water!
• Decomposition

  Organic matters are broken down by decomposers into simpler compounds. Reactants: Complex organic compounds found in dead organic matter. Products: Carbon dioxide (CO2) + Water (H2O) + Nutrients
• Water cycle

  The continuous movement of water all around the Earth, driven by the Sun's energy.
• Fossilization

  The process by which an organism's remnants or traces are preserved in the fossil record
• Sedimentation

  The process by which sediments like sand, mud, and silt are deposited as a result of the action of water, wind, or ice. Sedimentary rocks form as sediment layers are compressed and cemented over time.
• Combustion

  A chemical reaction between a fuel and an oxidizer, usually oxygen, that generates heat and produces products like water vapor, carbon dioxide, and other combustion byproducts. It is crucial in many processes, including production, transportation, and energy.
• Processes of Water Cycle

  1. Evaporation

  2. Condensation

  3. Precipitation

  4. Sublimation

  5. Deposition

  6. Infiltration

  7. Percolation

  8. Runoff

  9. Transpiration
• Oceanic Carbon Cycle


  The procedures through which carbon dioxide (CO2) is transferred from the atmosphere to the oceans. It includes: Atmosphere-ocean gas exchange, Biological production and consumption, Carbon movement within the ocean.
• Carbon comprises Carbon dioxide (CO2), which is a greenhouse gas. Without this (and other greenhouse gasses in small quantities), the Earth would freeze.
• Evaporation

  The process of liquid turning into a gas, this gas is called water vapor. This occurs because of heat that makes the water molecules move faster and faster, so fast that they eventually escape as gas.
• Organic compounds are an essential part of the cells of all living organisms.