Assessing Human Impacts on Ecosystems

Learning Goals  Different soils have different characteristics that can be assessed. Human activities can have long- lasting effects on soil.  Water can be tested for the presence of pollutants such as heavy metals, pesticides, and fertilizers.  Human activities have affected Ontario’s terrestrial and aquatic ecosystems in many ways.

Soil  Loose covering on the ground containing a mixture of organic matter, minerals, and moisture 3 Types of Soil… 1. Loam: different sizes of rock = holds air/water, drains without drying out, FERTILE 2. Clay: very small tightly-packed rock = blocks roots, traps water 3. Sandy: large rocks = large spaces = root growth, air pockets, quick drainage

Assessing Soil Quality  Acidity - most organisms prefer ~ neutral pH (extremes damage tissues or make nutrient absorption difficult)  Soil erosion - soil loss when water/wind washes/blows it away. Plant roots hold topsoil in place & prevent this.  Crop rotation: plant different types of crops each year to replenish soil nutrients, especially nitrogen.

Love Canal  Neighborhood in Niagara Falls, NY (36 square blocks)  Formerly been used to bury 22,000 tons of toxic waste by Hooker Chemical Company (now Occidental Petroleum Corporation)  1953: Site sold to Niagara Falls School Board for $1, (deed detailing the presence of dangerous chemical wastes. It was developed, including construction activity that breached containment structures, allowing trapped chemicals to seep out.  1978: State emergency called - vegetation died, properties were destroyed, basements were uninhabitable, high rates of miscarriage & birth defects, 1/3 of people precancerous (leukemia)

Assessing Water Quality  Aquatic Organisms: type/# of indicator species reveals water safety (  bacteria populations make people sick)  Oxygen:  Dissolved O 2 : dictates which species can survive (  O 2 =  survival)  Biological O 2 demand: measures how fast O 2 is used up by microbes  pollution promotes microbe growth, which use up O 2  Acidity: Neutral is preferred, most fish die below pH of 5  Eutrophication: phosphorus & nitrogen from fertilizer runoff cause algae to grow; as it dies/decomposes, O 2 levels drop causing organisms to die

 Heavy Metals: 5+ times more dense than water, from waste or industrial processes  Bioaccumulation: gradual build-up of a substance in an organism’s body  Bio-magnification: heavy metal becomes more and more concentrated in each link in a food chain as one animal eats many contaminated animals

 Pesticides: kill unwanted organisms that attack crops/reduce yields (strictly controlled); can bio- magnify  DDT  In Canada until 1970s, built up in top predators  Peregrine falcons – made eggshells so thin that few hatched, almost went extinct  Modern pesticides last one growing season and then break down into less harmful substances.  DDT is used responsibly in mosquito-infested parts of Africa in homes and on nets to battle malaria! NormalDDT-poisoned

BP Oil Disaster  April 20, 2010 in the Gulf of Mexico on the BP-owned Transocean-operated Macondo Prospect  Following the explosion & sinking of Deepwater Horizon oil rig, a sea-floor oil gusher flowed for 87 days, until it was capped on July 15,  Est. total discharge 4.9 million barrels (210 million US gal; 780,000 m3).  The well was declared sealed on 19 September 2010 *BUT* some reports say it continues to leak!

Centralia, PA  86°C mine fire burning beneath the borough since 1962  Various theories as to how the 400-acre underground fire started, but it may continue to spread (for 100s of years)  1979: Locals became aware of the scale of the problem (gas station owner noticed temp when checking fuel level, sink holes opened)  Most has been abandoned or reclaimed by nature, but the remaining church St. Mary’s still holds weekly services  Indications of the fire: warning signs, steam vents, smoke from cracks in the ground, re-routed Route 61

Homework 1.Describe how sandy soil is different than clay soil. 2.Manure is often used by gardeners to fertilize soil. How might this be effective in replenishing soil nutrients? 3.Why is it important to test for bacteria in water reserved for human use? 4.At which level of the food chain does bio- magnification have the most impact? Explain.