COMMISSION ON ATMOSPHERIC CHEMISTRY (VI.2)
Number: 620/20/95
Title: Modeling Life Time and Degradability of Organic Compounds
Coordinator(s):
L. Klasinc and A.
Sabljic
Remarks: Joint project with Commission VI.3
Completion Date: 1997
Description:
The ability to measure or accurately estimate degradation processes
if of critically important to environ. risk assessment of comm.
chem. In the troposphere for most of their reactions with OH and
(at night) NO3 radicals are the most import. Lab. meas. of these
reaction rates are costly and time consuming and only a few hundreds
are avail. Thus it is an imperative to dev. methods that will predict
reactivity and lifetime for large sets of chem. for reliable risk
assessment. So far there are 3 approaches for such estimates a)
fragment contrib. meth. b) QSAR based on physico-chemical data and
c) ab initio MO calculation (environ. quantum chemistry) since the
project will analyze and evaluate these models there is a necessity
that it is done by IUPAC.
Objectives:
1. collect existing quantitative models for estimating (predicting)
tropospheric degradation of organic chemicals.
2. Develop a set of eval. crit. for the quality of these approaches
starting with a) non-class specific approaches (such as the Athenison
fragment contribution method) and b) QSAR models based on linear
correlation of OH(NO3) reactivity with ionization energies. All
models will be evaluate in terms of their accuracy and range of
applicability with particular emphasis on their precision and on
the advantage and limitations of each of them. The result will be
recommendations for reliable application of predictive models for
estimating lifetimes and degradation of organic compounds in air.
Progress:
Project completed - Conference proceedings published in Pure
Appl. Chem.,
70(7), 1319-1394, 1998, and Chemosphere.