Polynuclear aromatic hydrocarbons PNAs

Outside of carbon monoxide for which the toxicity is already well-known, five types of organic chemical compounds capable of being emitted by vehicles will be the focus of our particular attention these are benzene, 1-3 butadiene, formaldehyde, acetaldehyde and polynuclear aromatic hydrocarbons, PNA, taken as a whole. Among the latter, two, like benzo [a] pyrene, are viewed as carcinogens. Benzene is considered here not as a motor fuel component emitted by evaporation, but because of its presence in exhaust gas (see Figure 5.25). 

Polynuclear aromatic hydrocarbon (PNA) emissions were higher for EDS fuels in lab scale tests. These emissions appeared to be due to the pyrolysis of high molecular weight PNA into smaller ring structures. 

Hydrocarbons in New York Bight Surface Sediment. As an example of the problems involved let us consider the case of hydrocarbons in surface sediments of the New York Bight. Our previous work on alkanes and cycloalkanes in that area has been published (18). By applying the previously discussed criteria we were able to conclude that the bulk of the alkanes and cycloalkanes were of fossil fuel origin. The measurements of polynuclear aromatic hydrocarbons (PNAs) in one of our samples from this area indicated that the bulk of those hydrocarbons were of pyrolytic origin (19). 

Levels of polynuclear aromatic hydrocarbons (PNAs) reported in this work for marine organisms, foodstuffs, sediments, and wastewater streams were found to be in the low ppb range. Data obtained on sediments and shellfish indicate that these PNAs are not petroleum derived but arise from a higher temperature combustion source. This conclusion is based on the alkyl-substituted PNAs measured relative to the parent PNAs. Analytical methods applicable to PNA analysis are almost as varied as the number of laboratories doing-this type of work. This chapter describes the Exxon methods as they apply to various environmental samples. 

An elegant method in induce phosphorescence emission from a guest exploits the heavy-atom effect of heptakis(6-Br-6-deoxy- -CD). In nitrogen-purged dimethylformamide/water (4/1), solution phosphorescence emission from five polynuclear aromatic hydrocarbons (PNA), diben-zofuran, and dibenzothiophene was readily observed in the presence of 10" Br-functionalized P-CD [191]. 

NIOSH considers Carbon Black to be the material consisting of more than 80% elemental carbon, in the form of near-spherical colloidal particles and coalesced particle aggregates of colloidal size, that is obtained by the partial combustion or thermal decomposition of hydrocarbons. The NIOSH REL (10-hour TWA) for carbon black is 3.5 mg/m. Polycyclic aromatic hydrocarbons (PAHs), particulate polycyclic organic material (PPOM), and polynuclear aromatic hydrocarbons (PNAs) are terms frequently used to describe various petroleum-based substances that NIOSH considers to be potential occupational carcinogens. Since some of these aromatic hydrocarbons may be formed during the manufacture of carbon black (and become adsorbed on the carbon black), the NIOSH REL (10-hour TWA) for carbon black in the presence... 

The production of coke by the carbonization of bituminous coal leads to the release of chemically-complex emissions from coke ovens that include both gases and particulate matter of varying chemical composition. The emissions include coal tar pitch volatiles (e.g., particulate polycyclic organic matter [PPOM], polycyclic aromatic hydrocarbons [PAHs], and polynuclear aromatic hydrocarbons [PNAs]), aromatic compounds (e.g., benzene and p-naphthylamine), trace metals (e.g., arsenic, beryllium, cadmium, chromium, lead, and nickel), and gases (e.g., nitric oxides and sulfur dioxide). 

Reductive Remediation of Nonhalogenated Molecules. Na/NHa treatments can also destroy nonhalogenated hazardous conqraunds. Three classes pollutants will be mentioned here polynuclear aromatic hydrocarbons (PNAs), nitro- and nitrate-type explosive wastes and chemical warfare agents. The treatment of neat sanq>les of PNAs leads to destmction efficiencies of 99.99% for many of these conq)ounds including such examples as acenaphthene, benzo[a]anthracene, benzo[b]fluoranthene, benzo[g,h,l]perylene, chrysene, fluorandiene, fluorine, naphdialene and phenanthrene. With the exception of naphthalene and anthracene, conq)lex product mixtures are formed. Radical anion formation followed by protonation occurs sequentially leading to dihydro, tetrahydro and further reduced products (see Scheme 3). Depending on the reaction conditions, dimerization of intermediate radicals can occur to give dimers in various states of reduction. 

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