Hydrocarbons forest fires

The environmental occurrence of polycyclic aromatic hydrocarbons is mainly associated with dispersion of oil products and with various types of combustion. For these chemicals a kind of pre-industrial background exists, due to forest fires or to domestic wood burning. The sediments of the deepest strata were certainly deposited in the nineteenth century, when no significant industrial activities had been initiated. The ratio between PAH concentrations found in the sediments dated to this century, and the deepest ones, vary from 1.7 to 30, increasing from the beginning of the... 

McMahon, C.K. and S.N. Tsoukalas. 1978. Polynuclear aromatic hydrocarbons in forest fire smoke. Pages 61-73 in P.W. Jones and R.I. Freudenthal (eds.). Carcinogenesis —A Comprehensive Survey. Vol. 3. Polynuclear National Symposium on Analysis, Chemistry, and Biology. Raven Press, New York. 

Bush and forest fires, burning of agricultural waste Oxidation of hydrocarbons... 

Pyrene is used in biochemical research. Polycyclic aromatic hydrocarbons (PAHs) occur naturally in coal tar, fossil fuel combustion, forest fires, and open flame grilled meats. PAHs are found in cigarette smoke and in diesel emissions, when asphalt surfacing and tar roofing, and also in aluminum and coke plants. Pyrene was used in the 1930s as an insecticide. 

The emissions from smoldering combustion contain all the necessary compounds needed for the formation of photochemical smog. We have mentioned in Chapter 3 that four main components are necessary for the initiation of this tropospheric phenomenon sunlight, temperature above 18 °C, hydrocarbons and nitrogen oxides, and all of them are present during forest fires in Southeast Asia. 

From the standpoint of air pollution, halogenated hydrocarbons are particularly significant, especially the group of chlorinated hydrocarbons from anthropogenic sources, which include chemicals for plant protection, industrial solvents, cleansers and fire extinguishing agents. Among natural sources, forest fires also contribute to the emissions of chlorinated hydrocarbons. 

Among various natural sources, the largest amounts of chlorinated hydrocarbons are supplied into the air by forest fires. In the combustion of cellulose, 2.2 mg of methyl chloride are formed per 1 g of substance burnt. Anthropogenic sources include the combustion of PVC (polyvinyl chloride) wastes, burning of plants in agriculture and uncontrolled fires resulting from human activity. 

For most unsaturated hydrocarbons, addition of OH is the first and rate-limiting step of the photochemical reaction chain. In the case of aromatics, which are emitted from automobiles, forest fires and fuel wood burning [11], the addition reaction is reversible at atmospheric temperatures. The effective rate constant for removal of the aromatic depends on consecutive reactions of the adduct. Prior to LACTOZ, consecutive reactions with O2 had not been detected for benzene -OH... 

Incomplete combustion of oil and other carbonaceous materials, e.g., in internal combustion engines, industrial processes Bjprseth and Ekbmd, 1979), domestic heating, forest fires and intentional biomass burning Greenberg et al., 1984) is another source of polycyclic aromatic hydrocarbons (PAH), primarily to the atmosphere. Dry deposition and atmospheric precipitation are the principal vectors of their transport into surface seawater. Gustafsson et al. (1997) discussed the export of deposited PAH from surface waters by association with sinking particles. 

BAD AIR Forest fires are a significant source of polycyclic aromatic hydrocarbons, which make up the solid, cancer-causing particulates that come from combustion. 

Atmospheric hydrocarbons produced by living sources are called biogenic hydrocarbons. Vegetation is the most important natural source of non-methane biogenic compounds. Several hundred different hydrocarbons are released to the atmosphere from vegetation sources. Other natural sources include microorganisms, forest fires, animal wastes, and volcanoes. 

A very different type of food toxicity involves toxins that are produced during the food preparation process. For example, charbroiled meats or smoked products (e.g., fish, sausage) typically contain polycyclic aromatic hydrocarbons (PAHs), formed during the cooking process (including barbecuing). Therefore, you will be exposed to small amounts of these chemicals when you eat meats that have been char-broiled. PAHs are naturally produced through combustion. They are also formed from forest fires, and are considered products of incomplete combustion. PAHs are also present in diesel fuels and car exhaust, and in smoke released from chimneys. 

Following an aviation kerosin spill, hydrocarbons were detected in trout stream sediments and fish up to 14 months after the spill [13]. After a fire at a weed treatment plant in 1970 a large area of mixed forested ecosystem became contaminated with polycyclic aromatic hydrocarbons and creosote [66], High polyaromatic concentrations in stream sediments adversely affected micro- and meiobenthic communities at all trophic levels. Stein et al. [67] have studied the uptake by bethnic fish (English sole, Parophrys vetulus) of benzopyrene and polychlorinated biphenyls from sediments. Accumulation of contaminants from sediments was a significant route of uptake by English sole. 

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