Chapter 2 Notes: Cycles of Matter

Societal Uses of Water in Alberta

• About 97.5% of water consumed in Alberta is surface water (lakes, rivers).
• The rest comes from groundwater (rain/snow filtered through the ground).

Gathering Data and Information

• Categories of Water Use in Alberta:
  • How much water (in L) is used for this purpose?
  • Ways to reduce water use?
  • Is water quality affected? If so, what can be done to restore water quality?
  • Benefits of water use for this purpose?

Organizing Findings

• Group presentation of findings to the class.

Opinions and Recommendations

• Which water use should be decreased? Justify.
• Ways to decrease water use in that category.
• Is water use a basic human right (free), or should people pay more to encourage conservation?

Water Diversion

• Solution: Pipelines to divert water from other parts of Alberta for irrigation.
• Arguments for and against:
  • Benefits:
    • Growth of economically important crops.
    • Growth of important food crops.
    • Rural communities could use the diverted water in their homes and town buildings.
  • Costs:
    • Removal of large amounts of water from a particular source (bulk water removal) would be permanent.
    • Ecosystems that depend on the source of the diverted water could be negatively affected.
    • Diversion could introduce species, such as parasites, from the water source into ecosystems in the other region.
  • Discuss whether the risks of diversion outweigh its benefits.
  • What questions to evaluate the risks and benefits of a diversion strategy for a specific rural area?

Biogeochemical Cycles

• Autotrophs produce their own food but need matter to build cell structures and provide energy.
• Organisms require nutrients as energy sources or chemical building blocks.
• Example: Pea plants need sulfur, nitrogen, and phosphorus in usable forms.
• Heterotrophs convert nutrients into forms plants can use.
• Fertilizers provide accessible plant nutrients.
• Recycling of matter through biotic/abiotic parts of ecosystems provides organisms with essential nutrients.

Nutrient Reservoirs

• At each step in a biogeochemical cycle, substances are temporarily stored in nutrient reservoirs (organisms, soil, air, water).
• All cycles involve substances stored in reservoirs for varying times and substances moving through the environment.

Rapid Cycling of Nutrients

• Substances cycle between nutrient reservoirs relatively quickly.
• Example: Carbon moves from producer to consumer to decomposer, and back to the atmosphere.

Slow Cycling of Nutrients

• Substances accumulate and are stored for long periods in nutrient reservoirs.
• Fossil fuel deposits (coal, oil) are carbon reservoirs formed over millions of years.
• Organic matter built up without fully decomposing, subjected to intense pressure.
• Slow cycling: It can take millions of years for these substances to become available as nutrients.
• Elements like O, C, N, and S form compounds that easily travel in water and air, traveling around the world.
• Elements like Fe and P are found in soil and water but generally do not enter the atmosphere.

Carbon and Oxygen Cycles

• Plants consume billions of tonnes of carbon as CO_2 each year.
• Much of the CO_2 released back into the atmosphere comes from forest fires and the breakdown of organic matter by decomposers.

Carbon Dioxide Production in Plants and Animals

• Plants and animals both use glucose as an energy source and as a source of carbon to build cell structures; therefore, like animal cells, plant cells carry out cellular respiration.
• Amount of CO_2 plants produce by cellular respiration is very small compared to the amount plants take in during photosynthesis.
• Plants, animals, and decomposers play a role in the rapid cycling of carbon and oxygen.
• Photosynthesis produces oxygen gas (O_2), which is needed for cellular respiration.

Slow Cycling of Carbon

• Living organisms play an important role in the slow cycling of carbon.
• Photosynthetic organisms remove carbon dioxide from the atmosphere and incorporate carbon into organic matter.
• Forests act as carbon sinks (reservoirs that absorb more carbon than they emit).
• Deforestation accounts for the return of about 2 gigatonnes (Gt) of carbon to the atmosphere per year.
• Photosynthetic organisms in the ocean also incorporate carbon.

Ocean as a Carbon Sink

• The ocean is the largest carbon sink (38,000 Gt carbon as dissolved CO_2).
• Another 11,000 Gt of carbon lies on the ocean floor in methane hydrates (CH_4).
• Natural processes return carbon to rapid cycling quickly (forest fires) or slowly (weathering).
• Limestone rock contains carbon from calcium carbonate (CaCO_3).

Human Influence on Carbon Cycling

• Combustion of petroleum deposits releases carbon into the atmosphere.
• Atmospheric carbon dioxide levels have increased by about 30% since the industrial revolution.

Sulfur Cycle

• Organisms require sulfur for proteins and vitamins.
• Plants and algae use sulfur as sulfate (SO_4^{2-}), incorporating it into their cells.
• Decomposers return sulfur to the soil or atmosphere.
• Hydrogen sulfide (H_2S) smell indicates decomposers at work.

Role of Bacteria

• Bacteria use sulfur compounds in photosynthesis or cellular respiration.
• Different bacteria have different roles: sulfate reducers convert sulfate to sulfide, while sulfur oxidizers convert sulfide to elemental sulfur and sulfate.
• Waste from one type of bacteria is a required material for another type.

Acid Deposition

• Some sulfur is taken out of rapid cycling when bacteria convert it to sediments, eventually becoming part of rocks.
• Fossil fuel deposits contain sulfur.
• Volcanic activity also releases some of the trapped sulfur into the atmosphere as sulfur dioxide (SO_2).
• Sulfur dioxide reacts with oxygen and water vapor to form sulfurous acid (H2SO3) and sulfuric acid (H2SO4), resulting in acid deposition.

Human Activities

• Burning fossil fuels releases sulfur dioxide into the atmosphere.
• Production of sour gas is another source of sulfur emissions.
• Amount of sulfur released by human activities is far greater than that released by natural processes.

Nitrogen Cycle

• Nitrogen gas (N_2(g)) makes up 78.1% of Earth’s atmosphere.
• Nitrogen is an essential part of proteins and DNA.

Nitrogen Fixation

• Most organisms cannot use atmospheric nitrogen.
• Some bacteria convert nitrogen gas into ammonium (NH_4^+) in nitrogen fixation.
• Legume plants have nitrogen-fixing bacteria in root nodules.
• The bacteria fix nitrogen into ammonium, which is shared with the plants.
• Ammonium is also produced when decomposers break down organic matter (ammonification).
• Some soil bacteria convert ammonium into nitrite (NO2^-) and then into nitrate (NO3^-).
• Plants can use nitrate as a nitrogen source.

Denitrification

• Denitrifying bacteria convert nitrite or nitrate back into nitrogen gas.
• This occurs in environments where there is very little oxygen.

Crop Rotation

• Growing legumes one season and crops the next helps maintain high nitrogen content in the soil.

Phosphorus Cycle

• Phosphorus is an essential nutrient, but it is often available in only limited quantities in the environment.
• Phosphorus is concentrated in living organisms.
• Phosphorus is a part of cellular DNA and ATP and is a major component of bones and teeth.
• Unlike carbon, nitrogen, and sulfur, phosphorus does not cycle through the atmosphere.
• Phosphorus is found in soil and water, and weathering gradually releases the phosphorus trapped in rocks.

Phosphate Availability

• Animals obtain phosphorus by consuming foods.
• Producers, such as plants and algae, can only use phosphorus if it is in the form of phosphate (PO_4^{3-}), which dissolves in water.
  • Overgrowth of algae, called an algal bloom, produces large amounts of organic matter. As decomposers break down the organic matter, they use up the oxygen in the water, resulting in the death of fi sh and other aquatic life.

Algal Blooms

• Growth of algae in aquatic ecosystems is limited by available nutrients.
• Overgrowth of algae (algal bloom) produces large amounts of organic matter.
• Decomposers break down the organic matter, using up oxygen and killing fish.
• Excess nitrogen or phosphorus can cause algal blooms.
• Canadian scientists convinced the government to ban phosphates in soaps and detergents.

What's in the Water?

• Both human activities and natural processes affect water quality.
• Scientists monitor water quality by testing for chemical and biological contaminants and for pH.
  Investigating human activities affect local water quality: up stream of a city vs. downstream of the city, upstream of an animal farm vs. downstream of the animal farm, run-off from a freshly watered plant vs. run-off from a freshly watered and fertilized plant.
• Measureing and recording data on pH and water quality parameters in local water samples, Comparing data from different sources to determine the impact of human activities on water quality.

Matter and Energy Exchange

• Each biogeochemical cycle is unique, but all are similar and interrelated.
• All six cycles involve both the abiotic and biotic environment.
• Effects on the transfer of energy from producer to consumer to decomposer also affect the biogeochemical cycling of matter.

Biosphere

• Biosphere does not exchange significant amounts of matter with its surroundings; however, there is a constant input of energy into the biosphere from the Sun and a constant output of radiant energy (heat) to space.
• Amount of sunlight received by an ecosystem affects the amount and type of productivity in the ecosystem.

Productivity

• Productivity is the rate at which an ecosystem’s producers capture and store energy within organic compounds over time. Measured in energy per area per year (J/m^2/a) or biomass per area per year (g/m^2/a).
• For example, a forest has a very large biomass. The mass of its vegetation is greater than that of a grassland of equal size. But productivity of a grassland ecosystem may actually be higher during the growing season.
• Rate of productivity depends on Producers, the amount of light and heat available, and the amount of rainfall the system receives.
• In the ocean is determined by available nutrients and sunlight

UV Radiation

• Increased UVR on productivity, direct effects increasing UVR have on animals and indirect effects.
• Approximately ~6% of sunlight that reaches Earth’s surface is ultraviolet radiation (UVR).
• Over time CFCs, decomposed by UVR, were destroying the ozone layer.
• In 1987, 27 countries signed a global environmental agreement called the Montréal Protocol to Reduce Substances that Deplete the Ozone Layer

Biosphere in Balance

• Homeostasis is a state of balance with internal conditions of pH, sugars and ions remain within narrow limits within certain limits in spite of changing external conditions.
• In 1979, ecologist James Lovelock proposed the Gaia Hypothesis.

Gaia Hypothesis

• Hypothesis said to be that Biosphere acts like an organisms and maintaining enviormental condtions within certain limits as it needs both a constant input of energy and cycling of nutrients so that it maintains its interal balance.

Stromatolites

• Ancient Micro-orgranisms with Deposits holding clues about composition, the atmosphere lacked oxygen and ancient organisms. Over time organisms pile as sediementary rocks of stromatolies.

Replicating the Earth's Atmosphere

• Biosphere tries to replicate itself
• NASA created a program called Advanced Life Support

Model Model Biosphere

How to survive system with water with clear battle, ecosystem for observations.
Human affect through poision and water waste.

Sustainability

• Phytoremediation : process of Naturally degrade or remove contaminants, such as toxic hydrocarbons
• Plants produce compounds(root exudates)
• Clean contamination on site or remove it through chemical or biological method.