Ecological Footprints

What are humanity's effects on the Earth's ecosystems? ● Our ecological footprint is the land area and water that we require for our lifestyle. ● Land to live on ● Land to grow our food ● and build our things ● Land to get rid of our waste

The Earth can only give so much.. ● The Earth's Ecological Carrying Capacity is limited

The World Wildlife Fund did a study in 2003 and found.. ● There were 1.8 hectares (1 hectare = 1000 m²) ● of productive surface for every human on Earth. ● Then they calculated how many resources we're actually using.. ● Canadians use the equivalent of 7.6 hectares to maintain our lifestyle.

● More recent estimates (2008) state that it would take 1.4 Earth's to sustain humanity's lifestyle. ● We're past the Earth's Carrying Capacity.

Ecotoxicology ● Not only do we need to consider how much the world can give us (versus how much we are taking), we also need to consider whether we're poisoning the very planet that is sustaining us. ● That is the issue that ecotoxicology is concerned with. ● Eco – 'natural environment', ● toxic – 'poison', ● ology – 'study of'

Contaminants ● Harmful substances released into the environment are contaminants. They can be.. ● Inorganic – ex., lead, arsenic, mercury, toxic elements ● Organic – more complex, man-made (pesticides, PCB) ● Microbial – bacteria, viruses ● Radioactive – uranium, radon, radium,...

Three things determine a contaminant's toxicity. ● Concentration – how much has been released? ● The 'Toxicity threshold' is the concentration at which harm is done. ● Location – which organisms are affected? ● Length of exposure

Bioaccumulation/Biomagnification ● The concentration of a toxin can increase up the food chain (trophic levels)

Biotechnology to the rescue..! ● As we damage the environment, we also look for ways we can heal it. Certain species of bacteria and fungi can break down certain contaminants (biodegradation). The use of these organisms is called bioremediation. (Example, bacteria used to clean an oil spill). ● Plants and algae can also capture contaminants. They can then be harvested and stored. This is called phytoremediation.(Example, cabbages absorb heavy metals).

Human waste ● Human waste can add excess nutrients to aquatic ecosystems (eutrophication) and contains bacteria that can cause illness. ● We use treatment plants and septic tanks to filter and disinfect the waste water before it is returned to the environment.