Quinte waters in the broader context of the Great Lakes

An examination of of some historical and contemporary aspects; shipping and the environment [*]

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Ballast water is another cause of foreign species invasion. When ships deliver their export to a foreign country, they must fill the ship’s ballast with water to balance the ship if they have no import load to bring home. The foreign water is dumped in the Great Lakes and introduces non-native species to the water. Non-natives disrupt the habitat of indigenous species and may create serious imbalance in their natural environment. Zebra mussels are an example of a foreign species that has invaded the Great Lakes via ballast water with negative results. Zebra mussels produce anywhere from 30 000 to 1 million eggs per year and will attach themselves to any hard surface available. Their high reproduction rates and ability to clog waterways make zebra mussels a nuisance in the Bay of Quinte. Zebra mussels are filter feeders. They clear the water and eat PCBs, but once they die the PCBs are released back into the water. When water becomes too clear, light penetrates deeper into the water and stimulates excessive bacterial growth. Zebra mussels also interfere with other species by eating their food and latching onto them so their movement is hindered.

Toxic chemicals are another serious threat to Lake Ontario water quality. Lake Ontario is receiving the largest volume of "persistent toxic chemicals" out of all the Great Lakes, due to the amount of industrialisation on its shore. Lake Ontario is downstream of all the other Great Lakes, making it the receiver of a great deal of toxic pollutants. DDT and PCBs are the most well known chemicals found in Lake Ontario. Farmers used DDT as a cheap and effective insecticide in the 1940s, and it made its way into the water supply as agricultural runoff. DDT can cause reproductive and growth failure in birds and is highly toxic to fish. Fish contaminated with DDT pose a potentially fatal health threat to humans who consume them. DDT was first detected in the Great Lakes in 1960, and its use was banned in the early 1970s. However, DDT is capable of producing positive results, too. It is socially acceptable to use DDT in small doses as a method of killing potentially malaria-contaminated mosquitoes in order to save human lives in Africa.

PCBs are industrial chemicals found in sealing compounds, coolants in electrical components and paint additives. PCBs were first detected in the Great Lakes in the late 1960s. At this time, factories were dumping PCB waste into the Lakes because it was not yet recognized as being toxic. Human bodies that have been occasionally exposed to PCBs take a median of 2.6 years to break down lowly-chlorinated PCBs and a median of 4.8 years to break down highly chlorinated PCBs. If ingested by humans, PCBs can cause a host of nervous system damage including muscle spasms, weakness and numbness in arms and legs.

Mercury was first detected in Lake Ontario sediment in 1968. No one realized that dumping inorganic mercury could be harmful until scientists later discovered that marine bacterium converts the inorganic mercury into toxic methyl mercury. Methyl mercury settles in the fish’s tissues and is highly toxic to the birds or humans who consume the fish. Mercury poisoning is not to be confused with Ciguatera, a food borne illness, which is caused by the consumption of marine species containing high levels of ciguatoxins. The species containing ciguatoxins are mainly found in tropical areas.

The Deloro Mine site discharges arsenic and heavy metals into the Moira River and the Zwicks landfill site leaks leachate into the Bay of Quinte. Arsenic and leachate are examples of two toxins other than DDT, PCBs and mercury that can be found in the Bay of Quinte but the latter three remain the most notorious.

Aluminium and Chromium [click image to enlarge]	Copper and Iron [click image to enlarge]	Manganese and Zinc [click image to enlarge]

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