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HANDBOOK OF ECOTOXICOLOGY

Figurę 14.4 Sources of petroleum and PAHs in the environment. Arrows indicate the initial movement of PAH and petroleum into the air, water, and soil.

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Volcanoes

Forest and grass fires Industry, power generation Intemal combustion engines    6

Cities and towns, municipal discharges Pipeiine spills Oil fields and refineries Offshore oil platform Natural oil seep

Shipping accidents, intentional oil discharges War, terrorism, vandalism, theft    m

plete combustion of organie matter from previously mentioned sources.¹⁵ Aąuatic contamination by PAHs is caused by petroleum spills, discharges, and seepages; industrial and municipal waste-water; urban and suburban surface runoff; and atmospheric deposition.² Land contamination by PAHs is caused by petroleum spills and discharges, forest and grass fires, volcanoes, industrial and municipal solid waste, and atmospheric deposition.

14.4 ENVIRONMENTAL FATE

14.4.1    General Considerations

Petroleum is monitored as a liquid composed of a diverse array of thousands of compounds, but PAHs are monitored as a group of individual compounds with similar molecular structures. Polycyclic aromatic hydrocarbons from Iow- or high-temperature pyrolysis and pyrosynthesis of organie molecules have similar fates in the environment. Whereas PAHs from crude and refined oils and coal originate from a concentrated hydrocarbon source, PAHs produced by high temperaturę (combustion or industrial processes) are dispersed in the air, scattered on the ground, or included as a component of liąuid waste and municipal sewage discharges.

14.4.2    Physical and Chemical

Petroleum discharged on water spreads ąuickly to cover large areas with a layer of oil varying from micrometers to centimeters thick. Some oils, especially heavy crudes and refined productś,