Environmental Science
Is concerned with the rapidly increasing human population, the use and abuse of resources, damage caused by pollution and disturbance, and the endangerment and extinction of species and natural ecosystems.
What are characteristics of a sustainable economic system?
Efficient use of non-renewables; use renewables <renewal rate; limited permanent environmental damage; equitable social/economic interactions
Examples of renewable resources
Biological: wild plants and animals, forest products; non-biological: surface and ground water, sunlight, wind and waves
What is true of all species?
potential fecundity and productivity are greater than the actual recruitment, growth and maturation of new individuals and biomass
Economy
a community system that used production, distribution, and consumption of goods and services to produce wealth
What are problems with using GNP/GDP?
ignores environment or resource base; ignores negative impacts; ignores positive environmental effects; no information on economic equitability
What is the big problem with the economy?
The economy is considered separately from the environment
What is exchanged in an economy?
Resources and services
What are grassland services?
Carbon storage, water regulation, erosion control, soil formulation, waste treatment, pollination, biological control
What are wetland services?
water storage and buffering, flood control, nutrient removal and buffering, sediment removal, food production, recreation
How is Energy Return on Investment Calculated (EROI)?
usable energy/energy expended
Hydrogen fuel cell
Very efficient, but expensive to produce; only water vapour comes out of exhaust
Hybrid vehicles
switch between electricity and diesel
What is the best solution to our power shortages?
- efficient lighting 2. Efficient motors 3. Eliminate waste 4. Solar heating 5. Machine efficiency
How is water used or lost?
- Evaporated to the atmosphere sooner than otherwise (decreases amount available to downstream users) 2. pollution-no longer useful 3. Suppress natural assimilation of wastes 4. Geological injection into the ground (fracking-makes water unusable)
Why are forests cleared?
- subsistence fuel 2. industrial fuel 3. lumber, paper 4. Agricultural land
What is the breakdown of world food supply sources?
croplands-77%; rangelands (livestock)-16%; oceanic fisheries-7%
What are natural environmental stressors?
biotic interactions-parasites; abiotic constraints and damage-storms and extremes in weather
What are the two types of disturbances?
Chronic or acute
Exposure
interaction between organism and stressor and the intensity (dose) over time
Tolerance
resistance to stressors
What are the responses to stressors?
- Individual function reduced 2. Individual mortality increased 3. Reduced species richness 4. Depleted nutrients and biomass 5. Net production can go negative 6. Sensitive species replaced by tolerant species (weeds) 7. Top predators and large-bodied species lost 8. Ecosystem not self-sustaining
Contamination
stressors at sub-damaging levels
Pollution
measurable damage to organisms
What are examples of anthropogenic pollutants?
- emissions of toxins 2. emissions of toxin generators 3. atmospheric/soil degrading compounds 4. Industrial heat-changes biology 5. sewage or fertilizer
Ecotoxicology
study of the directly poisonous effects of chemicals in ecosystems, plus indirect effects such as changes in habitat or food abundance caused by toxic exposures
Environmental risk assessment
Quantify risk to humans, other species and ecosystems: 1. probability of exposure 2. intensity of exposure 3. Biological damage possible
Reliability of a system
=reliability of technology x reliability of human
What do dose response curves do?
quantify risk, show safety/environmental standards, and show the acceptable level of toxins
Desirability quotient
societal benefits/societal risks
What are the problems with risks assessments?
Benefits and risks to ppl are different; short vs. long term; risk perception is inaccurate
Precautionary principle
An approach to environmental management, adopted by any countries at the 1992 Earth Summit, which essentially states that scientific uncertainty is not a sufficient reason to postpone control measures when there is a threat of harm to human health or the environment
What is the composition of the troposphere?
turbulent; Nitrogen-78%, Oxygen-21%, Carbon dioxide-.04%, Water vapour-.01%-5%
Composition of stratosphere
calm; 1000 x less water than troposphere and 1000x more ozone
Atmospheric inversion
When cold air gets trapped under warm air; smog and killer smogs (trap pollutants); normal mixing is inhibited
Hydrogen sulphide
H2S; highly toxic; smells like rotten eggs; given off by rotting of organic material; we can detect it 1 ppb
Sulphur dioxide
SO2
Sulphuric acid
H2SO4; H2S and SO2 transform into this; in acid precipitation in the East; residence time is 4 days
LRTAP
Long range transport of air pollutants
How are sulphur gases produced anthropogenically?
3.55x as much as naturally produced; fossil fuel combustion (smelters, generators, hard coal)
How do sulphur gases affect animals and plants?
not very toxic to animals; acute damage to plants (hidden injury-decreased yields)
Nitrogen gases
nitric oxide (NO); nitrogen dioxide (NO2); nitrous oxide (N2O)-laughing gas; NH3-ammonia; relatively low toxicity to plants and animals
Nitrogen dioxide
fossil fuels; 16% beyond natural; oxide to nitrate (NO3-, acid precipitation); ozone generation
Tropospheric ozone
secondary pollutant; result of primary pollutants-NOx and hydrocarbons react; humans and animals are very sensitive; plants are highly sensitive
Stratospheric ozone
good thing; filters UV-B rays; destroyed by NOx, N2O, chlorine, bromine, fluorine, and CFC’s
Chloroflurocarbons (CFC’s)
don’t occur naturally; stable in the troposphere; unstable in the stratosphere: chlorine breaks up zone
What is projected to happen if greenhouse gases continue to increase?
northern hemisphere warms faster than the southern; at mid-high latitudes the temp. will increase 2-3x global avg. increase; decrease in soil moisture; shifting of biomes and ecozones (grasslands will become deserts)
Climate change
Long term change in the weather that a region experiences
What are the major carbon dioxide activities?
Use of fossil fuels, manufacturing of cement, ecological conversions-forest to agriculture
What are the different kinds of stressors?
Physical stress, wildfire, chemical pollution, thermal pollution, radiation stress, climatic stress, biological stressors, biological pollution
Physical stress
Disturbance that involves an intense exposure to kinetic energy, which damages habitats and ecosystems. Eg: hurricanes, volcano, trampling
Wildfire
Involves the uncontrolled combustion of the biomass of an ecosystem.
Chemical pollution
Occurs when one or more substances occur in concentrations high enough to elicit physiological responses in organisms, potentially causing toxicity and ecological change. Eg. Pesticides, gases, toxic elements. Pollution can also result from excessive nutrients
Thermal pollution
Caused by the release of heat (thermal energy) into the environment, resulting in ecological stress because species vary in their tolerance of temperature extremes. May occur at natural springs
Radiation stress
Caused by excessive exposure to ionizing energy. Can be emitted by nuclear waste or explosions, or x-rays or UV radiation
Climatic stress
Associated with insufficient or excessive regimes of temperature, moisture, solar radiation, wind, or combinations of these
Biological stressors
Associated with interactions among organisms, such as competition, herbivory, predation, parasitism, and disease.
Biological pollution
Occurs when humans release organisms beyond their natural range. Eg. Introducing an alien species that invades and alters natural ecosystems; release of pathogens into the environment through discharges of raw sewage
GDP
Gross domestic product; an economic indicator related to the total size of a national economy.
What contributed to the depletion of the cod stock?
More efficient technologies, the use of sonar equipment to locate fish, increases in shipborne capacity to store and process fish
Dose response relationship
The quantitative relationship between different doses of a chemical and a biological or ecological response