[Text reading: Thurman and Trujillo Ch 18 pp. 519-535]
1. Marine Pollution – the introduction of human substances or energy into the marine environment resulting in a change of the water or substrate properties. The properties of a pollutant depend on its concentration, quantity and toxicity.
2. Oil: Natural marine seeps account for 46% of the oil in the ocean; other oil results from human introduction through marine transport of petroleum products; offshore drilling; nearshore refining; street runoff; and oil spills. Oil spills make up only a small percentage, but have great socioeconomic impact, AND small residues can have disastrous impacts on fauna. [see PDF on mortality of marine iguanas in the Galapagos].
a) Oil spill response techniques: At sea: enhancement of natural dispersion of the oil by using dispersant chemicals, containment and recovery of oil using booms and skimmers. On shore: Pressure washing with hot water and detergents or dispersants; in-situ burning and biodegradation with micro-organisms and/or nutrients.
c) Long-term impacts of oil spills to birds and mammals include lower reproduction rates and physical mutations in offspring. Some research indicates that oil can remain in sediments for hundreds of years. [See link to Peterson et al. 2003 Science paper]
3. Solid wastes
a) Plastic accounts for nearly 8% of solid wastes and many types take hundreds of years to decompose. Sea turtles mistake plastic bags for jellyfish, while seals and birds get tangled in net debris and other plastics. Incineration is not a great solution. Recycling is better.
b) Sediment from runoff from mining, farming and forestry can bury organisms, impede photosynthesis, clog gills & interfere with filter feeding.
c) Sewage: The sludge that results from primary treatment is organic matter containing viruses, bacteria and toxic metals. Quantity is a problem for disposal.
4. Synthetic organic chemicals: particularly halogenated hydrocarbons. These are used in pesticides, as flame retardants, industrial solvents, and cleaning fluids.
· Chlorinated Hydrocarbons are most abundant and dangerous, e.g., DDT pesticide.
Polychlorinated biphenyls (PCBs) are implicated
in viral epidemics in striped dolphins in the western
5. Heavy metals: A) Mercury: Levels are rising at an estimated 4.8% per year in the marine environment. Sources are industrial waste effluent; coal fired plants; municipal waste combustion; hospital waste incineration. Mercury causes neurological disorders, kidney damage, birth defects, insanity, AND accumulates in the food chain. B) Lead – arises from industrial waste, land fills, gasoline residue in runoff, and incineration of municipal waste; also causes neurological disorders. C) Tributyl Tin – antifouling paint additive, immunosupressor and causes sterility in snails (mascularization of females = imposex), and also accumulates in food chain. On all ships over 25 m (until 2008). Retained in the environment.