Nitrogen from nitrogen compounds constitute a much smaller percentage 1% by weight) of petroleum than do sulfur compounds. The nitrogen is also present in the form of derivatives of the heterocyclic ring systems such as thiazole or substituted quinolines.

Metals are present in petroleum either as salts of carboxylic acids or as porphyrin chelates (Chapter 9). Aluminum, calcium, copper, iron, chromium, sodium, silicon, and vanadium are found in almost all samples of petroleum in the range of 0.1-100 ppm. Lead, manganese, barium, boron, cobalt, and molybdenum are observed occasionally. Chloride and fluoride also are commonly encountered. Some of these metallic components are probably introduced into the petroleum when it is removed from the ground. The use of emulsified brines and drilling muds (mixtures of iron-containing minerals and aluminum silicate clays) may account for the presence of some of these trace elements.

The major environmental effects of petroleum are due either to crude oil itself or to the automobile hydrocarbon emissions from the gasoline fraction of the crude oil. Oil spills are generally associated with the release of hydrocarbons to the oceans or other water bodies, where much of the oil floats and spreads over large areas of the water surface. Spills on land tend to be more easily contained to small areas, but they may result in the contamination of soil and local water supplies. This has been an important problem in cases of storage tanks that leak petroleum into the underground environment over long period of time. The primary environmental problems associated with spills in bodies of water

Thiazole 2,3,8-Trimethylquinoline

Thiazole 2,3,8-Trimethylquinoline

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