DESTROYING ECOSYSTEMS In the past Earth’s natural waters were assumed to be infinite in their ability to absorb and remove the by-products of human populations - “dilution was the solution to pollution”. Today, we realize that “we all live downstream”. Pollution is generally divided into two classes: a. Point Sources - where the source can be identified, regulated or prosecuted b. Non-Point Sources - where no single entity is responsible, such as runoff from over -fertilized yards or oil stained highways and parking lots

Types of Pollution: 1. Sewage - greatest single source of ocean pollution It is the most harmful because it often contains mixtures of all the other types of pollution. High bacteria counts, particularly of E. Coli (also called fecal coliform) points to serious pollution and potential health hazards.

2. Oil - sources are oil tanker accidents (“Exxon Valdez” was only the 20th worst spill), offshore drilling, runoff, natural seeps, and eco-terrorism Oil mats marine bird’s feathers so they can’t fly, catch food or keep warm. When marine mammals ingest oil, the result is liver damage and hypothermia. Oil also coats benthic organisms, larvae and eggs. It prevents evaporation and gas exchange at the surface , resulting in suffocation.

3. Thermal - sources are discharges from industries using water for cooling which raises the temperature an average of 12 degrees. Changes all the other properties of water Most organisms can only tolerate 3-5 degree C increase.

4. Chemical - sources are industry, pesticides & runoff into storm drains Biomagnification is a process by which organisms concentrate toxins in the exchange of energy in food webs. Bioaccumulation – is the increase in concentration of a substance in living organisms as they take in contaminated air, water, or food.

Notable examples such as mercury poisoning in Minimata Bay, Japan and the nuclear meltdown at Chernobyl that produced birth defects and cancers in humans. Animals are also affected. For example, birds developed reproductive disorders like soft shells and crossed bills from DDT. There may be many hidden connections linking chemicals in our food, water and air to a variety of disorders and disease. High phosphate and nitrates cause algae blooms that block sunlight and gas exchange. Bacteria decomposing organic material further reduce oxygen levels.

It may later cause suffocation, strangulation or digestive blockages. 5. Garbage and Dumping - Sources may be individuals, industry or the government. Activities such as dredging, fishery by-catch and ships dumping millions of tons/yr of trash increase the problem. Animals become entangled in pop-tops, six-pack rings or mistake non-biodegradable substances and plastics for food. It may later cause suffocation, strangulation or digestive blockages. NOAA

6. Acid rain created by emissions from industry, cars and space shuttle launches. When the pH is altered, enzymes for metabolism are affected and limits for tolerance of other tissues may be exceeded. Acid rain is formed from carbon dioxide (naturally in the atmosphere) and when sulfur and nitrogen oxide are emitted into the air from burning of fossil fuels. As precipitation (rain, dew, snow, etc.) falls, it combines pollutants with oxygen and water to form carbonic, sulfuric and nitric acids. Acids restrict the formation of shells and prevents enzyme activity.

7. The Greenhouse Effect results in atmospheric heating 7. The Greenhouse Effect results in atmospheric heating. It is caused by an increase in carbon dioxide levels that prevent infrared light from escaping the atmosphere. This results in world wide temperature increases. With warmer temperatures, the sea level could rise as glacial ice melts. Thus salinity, density and coastlines would change. However, scientists do not agree on many of these issues. The bottom line is that we were already polluting the Earth by the time we started to take base line measurements.

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