Volatile organohalogen

Volatile Organohalogens produced by marine algae and seaweed... 

Moore RM (2003) Marine Sources of Volatile Organohalogens. In Gribble GW (ed) Natural Production of Organohalogen Compounds, The Handbook of Environmental Chemistry, vol 3, part P. Springer, Berlin, p 85... 

Moore RM, Tokarczyk R, Tait VK, Poulin M, Geen C (1995) Marine Phytoplankton as a Natural Source of Volatile Organohalogens. In Grimvall A, de Leer EWB (eds) Naturally-Produced Organohalogens. Kluwer, Dordrecht, p 283... 

Latumus F (2001) Marine Macroalgae in Polar Regions as Natural Sources for Volatile Organohalogens. Environ Sci Pollut Res 8 103... 

Murphy CD, Moore RM, White RM (2000) An Isotope Labeling Method for Determining Production of Volatile Organohalogens by Marine Microalgae. Limnol Oceanogr 45 1868... 

Tokarczyk R, Moore RM (1994) Production of Volatile Organohalogens by Phytoplankton Cultures. Geophys Res Lett 21 285... 

Semi-volatile organohalogen compounds, such as PBDEs, exist in the atmosphere in the gas-phase or associated with the particle-phase. The partitioning of compounds between these atmospheric phases is an important factor in their subsequent fate, transport, degradation, and human exposure assessment. Particle-to-gas partitioning is controlled largely by the physical properties of a compound, such as its vapor pressure and by the prevailing environmental conditions, such as the atmospheric temperature. As noted above, in the Strandberg et al. study, the samples were selected from days when the atmospheric temperature was 20 3 °C [42], At this temperature, the PBDEs were present in both the particle- and gas-phases, except for BDE-209, which was present only in the particle-phase. 

Tokarczyk R. and Moore R. M. (1994) Production of volatile organohalogens by phytoplankton cultures. Geophys. Res. Lett. 21, 285-288. 

Rosenberg C, Nylund L, Aalto T, et al. 1991. Volatile organohalogen compounds from the bleaching of pulp occurence and genotoxic potential in the work environment. Tenth International Symposium on Chlorinated Dioxins and Related Compounds 1990, Part 2, Bayreuth, Germany, Sept 10-14,... 

Macrophytic and phytoplanktonic algae produce a wide range of volatile organohalogens including di- and tri-halomethanes and mixed organohalogens. There is evidence for the involvement of enzymatic synthesis of methyl halides, but the metabolic... 

Bocchini, R Pozzi, R. Andalo, C. Gafletti, G.C. Membrane inlet mass spectrometry of volatile organohalogen compounds in drinking water. Rapid Commun. Mass Spectrom. 1999,13, 2049-2053. 

The antimony oxide/organohalogen synergism in flame retardant additives has been the subject of considerable research and discussion over the past twenty-five years (1-17). In addition to antimony oxide, a variety of bismuth compounds and molybdenum oxide have been the subject of similar studies (18-20). Despite this intensive investigation, relatively little has been conclusively established about the solid state chemical mechanisms of the metal component volatilization, except in those cases where the organohalogen component is capable of undergoing extensive intramolecular dehydrohalogenation. 

In the earlier literature, several different mechanisms have been proposed to account for the antimony volatilization which occurs during the combustion of polymer substrates in the presence of antimony oxide and an organohalogen. 

For those organohalogen compounds which can undergo intramolecular dehydrohalogenation, reaction sequence [1] has been proposed as the principal route to the generation of volatile antimony containing species (3, 5, 7, 18, 20). ... 

For those organohalogen compounds which cannot readily undergo intramolecular dehydrohalogenation, two alternative reaction sequences, (2) and [3], for the generation of volatile antimony containing species have been proposed (9, 21, 22). 

More recently, based on the results of an extensive series of small scale degradation studies, two additional mechanisms for the volatilization of antimony from antimony oxide/organohalogen flame retardant systems have been proposed (23,24). Of these two proposed mechanisms, [4] and [5], [4] does not involve HX formation at all and [5] suggests an important role for the direct interaction of the polymer substrate with the metal oxide prior to its reaction with the halogen compound. 

Mechanism [5] was based on the results obtained from multi-step sequential pyrolysis experiments in an inert atmosphere (23). This mechanism [5] differs from [3], primarily in that [5] was proposed to be surface catalytic in nature, and that the reaction between the oxide particle surface and the organohalogen was considered only as the first step, initiating the process leading to the eventual formation of volatile antimony species. 

As this work progressed, it became convenient for comparative purposes to express the pyrolysis results for a specific pyrolysis experiment in terms of the extent of the observed reaction of the initial organohalogen component content recovered chromatographically. The extent of reaction data as determined by the CGC analysis of the volatile reaction products for the pyrolysis of some representative simple mixtures of DBDPO are summarized in Table II. As illustrated by these data, the results obtained for the DBDPO/Sb203 mixture suggest that, in the absence of a polymer substrate, Sb203 exhibits the same extent of reaction as observed for other inert fillers such as glass beads or alumina. 

Organohalogenated compounds, referred to here as halocarbons, are widely distributed in the environment (1-4). Some industrially produced compounds, such as polychlorinated biphenyls and DDT [l,l -(2,2,2-tri-chloroethylidene)bis[4-chlorobenzene]] are biologically refractory and toxic pollutants of water and land. Volatile synthetic halocarbons such as chlo-rofluorocarbons (CFCs), a significant component of the greenhouse gases in the atmosphere, cause depletion of the ozone layer (5). Halogenated compounds also are produced naturally. The widespread occurrence of natural... 

Kinetics Considerations. Kinetics concepts and data concerning halocarbon sources and sinks can be used for a variety of purposes. For example, such information is required in mathematical models to evaluate the fate and exposure concentrations of low-volatility toxic organohalogens in water (18, 19). Moreover, kinetics relationships and data concerning physical, chemical, and biological processes are needed to predictively model aquatic sinks of volatile halocarbons (11). 

Seaweeds contain hvmdreds of organohalogens (see Figure 4). Telfairine, like the synthetic insecticide findane, is a powerful insecticide. These organohalogens are used by marine fife in cfiemical defense (natural pesticides). Tire smell of tire ocean is likely due to the myriad volatile... 

---