CHEMISTRY
AND THE ENVIRONMENT DIVISION
COMMISSION ON WATER AND SOIL CHEMISTRY
Modeling lifetime and degradability of organic compounds in air,
soil, and water systems (IUPAC Technical Report)
A. Sabljic1 and W.
Peijnenburg2*
1Institute Rudjer Boskovic, P.O. Box 180, HR-10002
Zagreb, Croatia; 2RIVM, Laboratory for Ecotoxicology, P.O. Box 1, NL-3720
BA Bilthoven, The Netherlands
Abstract: Degradability of organic compounds in air, soil, and
water is the most important factor for evaluating their environment
fate as well as possible adverse effects to humans and the environment.
The primary degradation process in the troposphere is the reaction with
the hydroxyl radical. For water and soil compartments, the primary degradation
process is biodegradation. The objectives of this report are: (i) to
review published models and their evaluation studies, (ii) to perform
an in-house evaluation of general models for estimating tropospheric
degradation and biodegradation of organic compounds, and (iii) to recommend
reliable procedures for estimating degradability of organic compounds
in the environment. The extensive evaluation procedure has shown that
the most accurate method for estimating tropospheric degradation is
Atkinson's group contribution method. Although this method has some
limitations, it seems to be a method of choice. A viable alternative
to Atkinson's method is a direct calculation, performed today almost
routinely, of the reaction rate constants with hydroxyl radicals. Recently,
a methodology based on reliable semiempirical potential energy surfaces
was developed that enables the calculation of reaction rate constants
within a factor of 2 of their measured values. A partial least squares
(PLS) model and a set of seven biodegradation rules have been found
to be the most reliable in estimating complete biodegradation of organic
compounds. However, it is recommended to use all four evaluated methods
to estimate biodegradation in the environment. If their results agree,
such estimates are very reliable.
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*Corresponding author
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