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@PHDTHESIS{Wolters:29919,
author = {Wolters, Andre},
title = {{P}esticide volatilization from soil and plant surfaces:
{M}easurements at different scales versus model predictions},
volume = {4073},
issn = {0944-2952},
school = {Techn. Hochsch. Aachen},
type = {Dr. (FH)},
address = {Jülich},
publisher = {Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag},
reportid = {PreJuSER-29919, Juel-4073},
series = {Berichte des Forschungszentrums Jülich},
pages = {IX, 127 p.},
year = {2003},
note = {Record converted from VDB: 12.11.2012; Aachen, Techn.
Hochsch., Diss., 2003},
abstract = {Simulation of pesticide volatilization from plant and soil
surfaces as an integral component of pesticide fate models
is of utmost importance, especially as part of the PEC
(Predicted Environmental Concentrations) models used in the
registration procedures for pesticides. Experimentally
determined volatilization rates at different scales were
compared to model predictions to improve recent approaches
included in European registration models. To assess the
influence of crucial factors affecting volatilization under
well-defined conditions, a laboratory chamber was set-up and
validated. Aerodynamic conditions were adjusted to fulfill
the requirements of the German guideline on assessing
pesticide volatilization for registration purposes.
Determination of soil moisture profiles of the upper soil
layer illustrated that a defined water content in the soil
up to a depth of 4 cm could be achieved by water-saturation
of the air. Cumulative volatilization of
$^{14}$C-parathion-methyl ranged from 2.4\% under dry
conditions to 32.9\% under moist conditions revealing a
clear dependence of volatilization on the water content in
the top layer. At the semi-field scale, volatilization rates
were determined in a wind-tunnel study after soil surface
application of pesticides to gleyic cambisol. The following
descending order of cumulative volatilization was observed:
chlorpyrifos > parathion-methyl > terbuthylazine >
fenpropimorph. Parameterization of the models PEARL
(Pesticide Emission Assessment at Regional and Local Scales)
and PELMO (Pesticide Leaching Model) was performed to mirror
the experimental boundary conditions. Model predictions
deviated markedly from measured volatilization fluxes and
showed limitations of current volatilization models, such as
the uppermost compartment thickness having an enormous
influence on predicted volatilization losses. Moreover, the
impact of soil moisture on volatilization from soil was not
reflected by the model calculations. Improvements of PELMO,
including the temperaturedependence of water-air
partitioning, the reduction of the compartment size of the
top layer and the introduction of a moisture-dependent
sorption coefficient, contributed to a more realistic
reflection of experimental findings, especially at the
initial stage of the studies. Studies on volatilization from
plants included a field study and a wind-tunnel study after
simultaneous application of parathion-methyl, fenpropimorph
and quinoxyfen to winter wheat. Parathion-methyl was shown
to have the highest volatilization during the windtunnel
study of 10 days (29.2\%). Volatilization of quinoxyfen was
about 15.0\%, indicating a higher volatilization tendency in
comparison with fenpropimorph (6.0\%), which may be
attributed to enhanced penetration of fenpropimorph
counteracting the volatilization process. A mechanistic
approach using a laminar air-boundary layer concept for the
consideration of volatilization from plant surfaces was
adjusted and calibrated on the basis of a series of
wind-tunnel studies. Calibration of the thickness of the
air-boundary layer and the rate coefficients of
phototransformation and penetration into the leaves allowed
the implementation of this description in PELMO and enabled
the simultaneous estimation of volatilization from plants
and soil. The need to determine critical factors affecting
volatilization, especially phase partitioning coefficients,
resulted in the development and validation of a novel
chamber system for measurements of the temperature
dependence of the soil-air partitioning of fenpropimorph.
Additional batch studies allowed for the quantification of
the general tendency of pesticides towards enhanced soil
sorption after lowering the temperature.},
cin = {ICG-IV},
cid = {I:(DE-Juel1)VDB50},
pnm = {Chemie und Dynamik der Geo-Biosphäre},
pid = {G:(DE-Juel1)FUEK257},
typ = {PUB:(DE-HGF)11 / PUB:(DE-HGF)3},
url = {https://juser.fz-juelich.de/record/29919},
}