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The Importance of Long and Short-Term Air-Soil Exchanges of Organic Contaminants.

Jones, K. C. and Johnston, A. E. and McGrath, S. P. (1995) The Importance of Long and Short-Term Air-Soil Exchanges of Organic Contaminants. International Journal of Analytical Chemistry, 59 (2-4). pp. 167-178.

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Abstract

Retrospective analysis of archived soil samples collected and stored from long-term agricultural experiments in the UK has shown how soil organic chemical composition has changed over time. High molecular weight polycyclic aromatic hydrocarbons (e.g. benzo[a]pyrene) and polychlorinated dibenzo-p-dioxins and -furans have increased in concentration through this century as a result of cumulative atmospheric depositional inputs. Concentrations of polychlorinated biphenyls and low molecular weight hydrocarbons (e.g. phenanthrene) peaked in the late 1960s/early 1970s, but have declined subsequently. This reflects declining atmospheric inputs of these compounds and losses from surface soils by volatilisation back to the atmosphere and biodegradation. PCBs and low molecular weight PAHs exist predominantly in the vapour phase in air, whilst heavy PAHs and PCDD/Fs are predominantly particulate-bound. Outgassing from soils is probably the most important contemporary source of PCBs to the atmosphere in the UK. Future UK PCB air concentrations will presumably therefore be influenced (controlled) by the rate of desorption and outgassing, as soil and air concentrations move towards a condition of equilibrium partitioning. Archived soils collected and stored before the commercial manufacture of PCBs contain no PCBs indicating that there is no 'natural production' of these compounds. However, within a few hours of exposure to contemporary air these samples contain detectable quantities of PCBs. Short-term air-soil exchange, such as during soil drying in the laboratory, can lead to contamination of samples which contain low concentrations of PCBs and loss from samples which contain high concentrations.

Item Type: Article
Journal or Publication Title: International Journal of Analytical Chemistry
Uncontrolled Keywords: PAHs ; PCBs ; PCDDs ; soil samples ; atmospheric deposition
Subjects: G Geography. Anthropology. Recreation > GE Environmental Sciences
Departments: Faculty of Science and Technology > Lancaster Environment Centre
ID Code: 22285
Deposited By: ep_ss_importer
Deposited On: 06 Feb 2009 14:34
Refereed?: No
Published?: Published
Last Modified: 26 Jul 2012 15:58
Identification Number:
URI: http://eprints.lancs.ac.uk/id/eprint/22285

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