Tropospheric composition of organohalogens and alkyl nitrates: tropical and temperate case studies

Newton, Hannah M. (2011) Tropospheric composition of organohalogens and alkyl nitrates: tropical and temperate case studies. Doctoral thesis, University of East Anglia.

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Abstract

The tropospheric composition of organohalogens and alkyl nitrates have been investigated
from tropical and temperate environments. Ground based measurements and aircraft data
are presented from the Oxidant and Particle Photochemical Processes (OP3) project, conducted
in Borneo, 2008. Controlled experiments of temperate vegetation were also conducted
to assess the emission of methyl halides from crop plants. Methyl halide results
from OP3 contradict current assumptions of a strong source from tropical vegetation.
High mixing ratios of methyl chloride and chloroform were observed in the boundary
layer over oil palm plantations. OP3 aircraft data suggests that the oil palm plantations
facilitate the formation of C2 to C4 alkyl nitrates. There was evidence that the southeast
coast of Sabah is a source region for the bromocarbons measured. The short lived bromocarbons
contribute to a bromine budget of 4- 6 ppt; this corroborates recent modelling
estimates of their contribution to the stratospheric burden.
In controlled experiments it was confirmed that the gene responsible for the emission
of methyl halides is the HOL (HARMLESS TO THE OZONE LAYER) gene. The current
WMO estimate for rapeseed contribution to the natural methyl bromide budget was
shown to be an overestimate, based on the varieties studied in this thesis. Methyl iodide
emissions from rice plants grown in soils were observed to be significantly lower than reported
from rice paddies in the literature, suggesting that the growth conditions contribute
to the production of methyl iodide.

Item Type: Thesis (Doctoral)
Faculty \ School: Faculty of Science > School of Environmental Sciences
Depositing User: Brian Watkins
Date Deposited: 15 May 2013 10:37
Last Modified: 15 May 2013 10:37
URI: https://ueaeprints.uea.ac.uk/id/eprint/42397
DOI:

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