Journal of Atmospheric Chemistry 

About: Journal of Atmospheric Chemistry is an academic journal published by Springer Science+Business Media. The journal publishes majorly in the area(s): Aerosol & Ozone. It has an ISSN identifier of 0167-7764. Over the lifetime, 1461 publications have been published receiving 66551 citations.

Biogenic Volatile Organic Compounds (VOC): An Overview on Emission, Physiology and Ecology

Abstract: This overview compiles the actual knowledge of the biogenic emissions of some volatile organic compounds (VOCs), i.e., isoprene, terpenes, alkanes, alkenes, alcohols, esters, carbonyls, and acids. We discuss VOC biosynthesis, emission inventories, relations between emission and plant physiology as well as temperature and radiation, and ecophysiological functions. For isoprene and monoterpenes, an extended summary of standard emission factors, with data related to the plant genus and species, is included. The data compilation shows that we have quite a substantial knowledge of the emission of isoprene and monoterpenes, including emission rates, emission regulation, and biosynthesis. The situation is worse in the case of numerous other compounds (other VOCs or OVOCs) being emitted by the biosphere. This is reflected in the insufficient knowledge of emission rates and biological functions. Except for the terpenoids, only a limited number of studies of OVOCs are available; data are summarized for alkanes, alkenes, carbonyls, alcohols, acids, and esters. In addition to closing these gaps of knowledge, one of the major objectives for future VOC research is improving our knowledge of the fate of organic carbon in the atmosphere, ending up in oxidation products and/or as aerosol particles.

Water-soluble organics in atmospheric particles: A critical review of the literature and application of thermodynamics to identify candidate compounds

Abstract: Although organic compounds typically constitute a substantial fraction of the fine particulate matter (PM) in the atmosphere, their molecular composition remains poorly characterized. This is largely because atmospheric particles contain a myriad of diverse organic compounds, not all of which extract in a single solvent or elute through a gas chromatograph; therefore, a substantial portion typically remains unanalyzed. Most often the chemical analysis is performed on a fraction that extracts in organic solvents such as benzene, ether or hexane; consequently, information on the molecular composition of the water-soluble fraction is particularly sparse and incomplete. This paper investigates theoretically the characteristics of the water-soluble fraction by splicing together various strands of information from the literature. We identify specific compounds that are likely to contribute to the water-soluble fraction by juxtaposing observations regarding the extraction characteristics and the molecular composition of atmospheric particulate organics with compound-specific solubility and condensibility for a wide variety of organics. The results show that water-soluble organics, which constitute a substantial fraction of the total organic mass, include C2 to C7 multifunctional compounds (e.g., diacids, polyols, amino acids). The importance of diacids is already recognized; our results provide an impetus for new experiments to establish the atmospheric concentrations and sources of polyols, amino acids and other oxygenated multifunctional compounds.

Formation of Organic Aerosols from the Oxidation of Biogenic Hydrocarbons

Abstract: Measurements of aerosol formation during thephotooxidation of α-pinene, β-pinene,d-3-carene, d-limonene, ocimene, linalool, terpinene-4-ol, andtrans-caryophyllene were conducted in an outdoor smog chamber. Daylight experiments in the presence of NO_x and dark experiments with elevated ozone concentrations were performed. The evolution of the aerosol was simulated by the application of a gas/particle absorption model in connection with a chemical reaction mechanism. The fractional aerosol yield is shown to be a function of the organic aerosol mass concentration and temperature. Ozone and, for selected hydrocarbons, the NO_3 reaction of the compounds were found to represent efficient routes to the formation of condensable products. For initial hydrocarbon mixing ratios of about 100 ppb, the fractional aerosol yields from daylight runs have been estimated to be ∼5% for open-chain hydrocarbons, such as ocimene and linalool, 5–25% for monounsaturated cyclic monoterpenes, such as α-pinene, d-3-carene, or terpinene-4-ol, and ∼40% for a cyclic monoterpene with two double bonds like d-limonene. For the only sesquiterpene investigated, trans-caryophyllene, a fractional aerosol yield of close to 100% was observed. The majority of the compounds studied showed an even higher aerosol yield during dark experiments in the presence of ozone.

Sulfur Emissions to the Atmosphere from Natural Sources

Abstract: Emissions of sulfur gases from both natural and anthropogenic sources strongly influence the chemistry of the atmosphere. To assess the relative importance of these sources we have combined the measurements of sulfur gases and fluxes during the past decade to create a global emission inventory. The inventory, which is divided into 12 latitude belts, takes into account the seasonal dependence of sulfur emissions from biogenic sources. The total emissions of sulfur gases from natural sources are approximately 0.79 Tmol S/a. These emissions are 16% of the total sulfur emissions in the Northern Hemisphere and 58% in the Southern Hemisphere. The inventory clearly shows the impact of anthropogenic sulfur emissions in the region between 35° and 50°N.

Global distribution of natural freshwater wetlands and rice paddies, their net primary productivity, seasonality and possible methane emissions

Abstract: A global data set on the geographic distribution and seasonality of freshwater wetlands and rice paddies has been compiled, comprising information at a spatial resolution of 2.5° by latitude and 5° by longitude. Global coverage of these wetlands total 5.7×106 km2 and 1.3×106 km2, respectively. Natural wetlands have been grouped into six categories following common terminology, i.e. bog, fen, swamp, marsh, floodplain, and shallow lake. Net primary productivity (NPP) of natural wetlands is estimated to be in the range of 4–9×1015 g dry matter per year. Rice paddies have an NPP of about 1.4×1015 g y−1. Extrapolation of measured CH4 emissions in individual ecosystems lead to global methane emission estimates of 40–160 Teragram (1 Tg=1012 g) from natural wetlands and 60–140 Tg from rice paddies per year. The mean emission of 170–200 Tg may come in about equal proportions from natural wetlands and paddies. Major source regions are located in the subtropics between 20 and 30° N, the tropics between 0 and 10° S, and the temperate-boreal region between 50 and 70° N. Emissions are highly seasonal, maximizing during summer in both hemispheres. The wide range of possible CH4 emissions shows the large uncertainties associated with the extrapolation of measured flux rates to global scale. More investigations into ecophysiological principals of methane emissions is warranted to arrive at better source estimates.