Overheads (Two Lectures)

Lecture 1:

Ocean Pollution and Hazards
Both human and natural processes contribute to ocean pollution and oceanic conditions hazardous to humans

Ocean Pollution- I
There are both natural and human sources of oceanic pollution/ hazardous materials
Natural- volcanoes, erosion/ weathering, climate change
Human- solid and liquid waste, accidents, unintended chemical discharges

Ocean Pollution- II
Sources of pollution may be either:
Point sources (sources that are localized and easily?? identified- sewage outfalls or dump sites are examples)
Non-point sources (sources that are distributed over a large area and less easily identified- agrochemicals are one example)

Hazardous Substances
Bacteria/ parasites
Trace metals- e.g., mercury, lead
Chlorinated hydrocarbons- e.g., PCBs, Dioxin, DDT
Gases- e.g., carbon dioxide, methane
Organic wastes- e.g., sewage
Radioactive wastes- e.g., spent fuel from nuclear reactors

Sources of Hazardous Substances
Sewage waste
Manufacturing waste
Energy consumption
Trash disposal
Non-point sources (agrochemicals)


Lecture 2:

Human Impact in the Borderland
20 million people live along the edge of the borderland
Intermittent sewage dumps are common
Waters used for cooling power plants create locally anomalous warm ocean conditions
Threat of ocean dumping

Solid Waste Treatment

LA uses sanitary landfills for most solid waste
Other methods: burning, recycling
Ocean dumping no longer legal in USA
Many other countries still use ocean dumping

Water (Sewage) Treatment

Primary Treatment: physical filtering of water (rural septic tanks)
Secondary Treatment: physical filtering, aeration, chlorination, sometimes bacterial breakdown of organic matter (normal urban treatment)
Tertiary Treatment: add extra chemicals when organic content is high (Lake Tahoe in the 1970's)

Oil Pollution
Point Sources:
Tanker accidents
Natural seeps
Non-Point Sources
Urban runoff
Aerosols (car and industrial emissions)


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