Jürgen Hahn

The organic constituents of atmospheric particulate matter

Abstract The ether soluble fraction of atmospheric aerosol particles was separated into the following groups of compounds: organic acids and phenols, organic bases, aliphatic hydrocarbons, aromatic hydrocarbons and neutral compounds. These groups in turn were analyzed for individual constituents. Aerosol samples were collected from six different geographic regions: three over the European continent with different degrees of air pollution and three from Atlantic air masses. In all cases the organic fraction of atmospheric aerosol particles had a very complex composition. However, the relative composition with respect to the main groups of organic compounds remained fairly constant in all areas sampled. This indicates either a common origin or formative processes throughout the atmosphere resulting in a similar net product.

n-Alkane studies in the troposphere—I. Gas and particulate concentrations in north Atlantic air

Abstract Simultaneous measurements of gas phase and paniculate concentrations of C 9 –C 28 n -alkanes in clean air at the west coast of Ireland are reported. All n -alkanes were regularly present with gas phase concentrations between about 10 and 20 × 10 −9 g m −3 STP, showing no systematic decrease above C 13 . Continental air showed higher concentrations. The fraction of alkanes attached to aerosol particles increases from less than 1% at low C-numbers to several per cent at high C-numbers. The carbon preference index is generally close to 1.0; seawater samples from that area exhibit similar distributions of n -alkanes as the gas phase.

N-alkane studies in the troposphere—II: Gas and particulate concentrations in Indian Ocean air

Abstract Westerly winds arriving at the Australian Clean Air Baseline Station Cape Grim at the North Western tip of Tasmania have exceedingly long trajectories over the Indian Ocean. In these air masses we found the n-alkanes C 9 -C 28 to be always present in the gas phase and also in the aerosols. In aerosols we also measured total organic matter and its general composition. All these concentrations agree fairly well with our earlier data in marine air over the North Atlantic Ocean. Calculations of the life time of the gas phase n-alkanes due to reaction with OH radicals lead to the conclusion that these n-alkanes must be of oceanic origin in Indian Ocean air and — to a large extent — also in the North Atlantic air. The same conclusion is reached for the organic component in aerosols. Water Analyses show that the n-alkanes C 9 -C 28 seem to be normal constituents of the oceans.

ORGANIC CONSTITUENTS OF NATURAL AEROSOLS

The blue haze often observed over forested areas led Went’ to suggest the potential importance of vegetation as a major source of atmospheric hydrocarbons. Nearly 20 years have passed since, and although interest in the organic chemistry of the troposphere has been growing in recent years, the composition, distribution, and cycle of atmospheric organic matter have remained largely obscure. In an excellent review, Duce’ recently defined the state of knowledge in this field of air chemistry as primitive a t best. Information on vapor phase organic matter in remote areas, or even in nonurban continental areas, is extremely sparse. More data are available on airborne particulate organic matter. But even here, most studies have dealt with the urban situation or have concentrated on specific organic pollutants, such as DDT and other pesticides, polychlorobiphenyls (PCBs), and some polycyclic hydrocarbons. The understanding of the sources, sinks, and residence time and distribution in the troposphere of airborne particulate organic matter as a whole or of its various constituents is still very limited. This paper summarizes what is known about the organic constituents of natural aerosol particles and the abundance of particulate organic matter in the troposphere, and attempts, despite large uncertainties, to describe a cycle of tropospheric particulate organic matter.

Traces of archaebacteria in ancient sediments

Summary After burial in a sediment, organic matter is altered by various diagenetic processes to insoluble, highly polymeric kerogen and a lipid fraction, composed mainly of hydrocarbons. The as yet uninvestigated potential of factor 430, a porphinoid compound, to act as a marker for methanogenic archaebacteria is mentioned in relation to the petroporphyrins found in petroleums and sediments. The evidence for isoprenoid ethers and alkanes found in the geological record back to 3 billion years is summarized. An attempt is made to relate the findings to potential archaebacteria precursors. The C 18 –C 26 isoprenoid alkanes found in several facies of the oldest known sediments in the Isua district of W. Greenland are discussed with respect to the apparent metamorphic alterations of the host rocks. The evidence indicates that archaebacteria have existed for at least one billion years, possibly even for more than three billion years.

Bestimmung der organischen Bestandteile von Aerosolpartikeln aus Reinluft

The method developed for analysing the organic matter of atmospheric particles from clean air is based on the combination of classical separation procedures and thinlayer chromatography together with gas chromatography and gas chromatography/mass spectrometry, respectively. In contrast to methods published earlier, all organic compounds present can be detected (if they are or can be converted to compounds soluble in ether). The loss of organic matter inherent in the analytical procedure is small enough to allow the determination of the organic constituents of 100 mg of aerosol particles (with about 10% organic matter). An example for the application of the analytical method is presented.ZusammenfassungDas für die Untersuchung der organischen Bestandteile von Reinluft-Aerosolteilchen entwickelte Analysenverfahren beruht auf der Kombination von klassischen Trennmethoden mit Verfahren der Dünnschicht- und der Gas-Chromatographie bzw. der Gas-Chromatographie/Massenspektrometrie. Im Gegensatz zu älteren Verfahren werden alle vorkommenden organischen Verbindungen, soweit sie äther-löslich sind bzw. in eine äther-lösliche Form überführt werden können, erfaßt. Die verfahrensbedingten Substanzverluste sind so gering, daß schon 100 mg Aerosolteilchen ausreichend sind für die Analyse der organischen Bestandteile (bei ca. 10% organischer Substanz). Ein Anwendungsbeispiel für das Analysenverfahren wird gegeben. Best. von Organ. Substanzen in Luft; Chromatographie, Dünnschicht/Chromatographie, Gas/Massenspektrometrie; Aerosolbestandteile in Reinluft.