Man Made Perils Examples Ozone Depletion Acid Rain Pollution Man Made Perils/hazards - These are caused by human activity to the Earth. A hazard/peril is global when it impacts on earth’s life sustaining systems. Examples Ozone Depletion Acid Rain Pollution Global Warming Deforestation Desertification Nuclear threat Species extinction/ loss of biodiversity Genetic Erosion

Ozone Depletion The ozone layer is a belt of naturally occurring ozone gas that sits 9.3 to 18.6 miles (15 to 30 kilometers) above Earth and serves as a shield from the harmful ultraviolet B radiation emitted by the sun.

What is ozone? Ozone is a highly reactive molecule that contains three oxygen atoms. It is constantly being formed and broken down in the high atmosphere, 6.2 to 31 miles (10 to 50 kilometers) above Earth, in the region called the stratosphere

What are the effects of ozone depletion? The ozone layer is deteriorating due to the release of pollution containing the chemicals chlorine and bromine. Such deterioration allows large amounts of ultraviolet B rays to reach Earth, which can cause skin cancer and cataracts in humans and harm animals as well.

How the ozone layer protects us

Illnesses in humans caused by overexposure to UVB rays Skin Cancer Cataracts Suppressed immunity

Effects on the environment Extra ultraviolet B radiation reaching Earth also inhibits the reproductive cycle of phytoplankton, single-celled organisms such as algae that make up the bottom rung of the food chain. Biologists fear that reductions in phytoplankton populations will in turn lower the populations of other animals. Researchers also have documented changes in the reproductive rates of young fish, shrimp, and crabs as well as frogs and salamanders exposed to excess ultraviolet B

How humans contribute to the problem: Chlorofluorocarbons (CFCs), chemicals found mainly in spray aerosols heavily used by industrialized nations for much of the past 50 years, are the primary culprits in ozone layer breakdown. When CFCs reach the upper atmosphere, they are exposed to ultraviolet rays, which causes them to break down into substances that include chlorine. The chlorine reacts with the oxygen atoms in ozone and rips apart the ozone molecule.

Aerosol Cans One atom of chlorine can destroy more than a hundred thousand ozone molecules, according to the the U.S. Environmental Protection Agency.

Impact on the Arctic The ozone layer above the Antarctic has been particularly impacted by pollution since the mid-1980s. This region’s low temperatures speed up the conversion of CFCs to chlorine. In the southern spring and summer, when the sun shines for long periods of the day, chlorine reacts with ultraviolet rays, destroying ozone on a massive scale, up to 65 percent. This is what some people erroneously refer to as the "ozone hole." In other regions, the ozone layer has deteriorated by about 20 percent.

More Developed Countries About 90 percent of CFCs currently in the atmosphere were emitted by industrialized countries in the Northern Hemisphere, including the United States and Europe. These countries banned CFCs by 1996, and the amount of chlorine in the atmosphere is falling now. But scientists estimate it will take another 50 years for chlorine levels to return to their natural levels.

Pollution and Waste Disposal Man Made Peril

Pollution Any material produced by humans in quantity and disposed of in such a way that it interferes with the health of living organisms and with the natural environments and processes of Earth.

Types of pollutants Persistent pollutants- materials that remain in the environment for many years without breaking down. Pesticides, heavy metals like lead Non-persistent pollutants-biodegradable. Human waste, food

Air Pollution Primary pollution- directly from industry, manufacturing, mining, refining or combustion Carbon dioxide-released from burning fossil fuels Carbon Monoxide-same as above (incomplete oxidation) Hydrocarbons (automobile exhaust, smokestacks) Particulates-smoke, dust, ash Sulphur dioxide-burning FF that contain sulphur Nitrogen oxides- from FF, creates smog

Secondary Air Pollution Smog Acid Rain

Water Pollution Domestic Sewage Animal and human waste Nitrogen and phosphate compounds Agricultural runoff Industrial wastes Silt and sediment Urban Runoff Marine Discharges Page 138- Animal and human waste comes from undigested food material often

The Hazards of Water Pollution Disease-causing bacteria, viruses and protozoa found in animal and human waste can affect those drinking the water. Cholera, dysentery and hepatitis are known contaminants. Too much nitrogen and phosphorous in water causes excessive growth of algae, blocking light to deeper water. Sediment caused by erosion can suffocate fish, aquatic vegetation and other organisms.

Waste Disposal How does Canada rank among other countries in terms of waste disposal? http://www.conferenceboard.ca/hcp/Details/Environmen t/municipal-waste-generation.aspx

Domestic Sewage Halifax, NS (population 372,679) pumped untreated sewage into the harbour until 2008. That’s anything that passes through toilets, sinks, bath and shower drains! Other methods- “settling lagoons”, aeration (creates sludge which can be dried and used in compost and fertilizers)

Solid Waste Packaging, paper, metal, glass, styrofoam Goes to Landfills Incineration Recycling

Hazardous and Toxic Wastes Items that are explosive, flammable or other dangers such as poison Issues Storage (how long will containers last?) Dumped in landfills (toxins leak into groundwater) Incinerated (dangerous fumes, poisonous ash) Ship to LLDCs????

Sydney Tar Ponds Read case study on page 149 Questions 5, 7 and 8 on page 152