Three-dimensional model evaluation of the Ozone Depletion Potentials for n-propyl bromide, trichloroethylene and perchloroethylene

D J Wuebbles,M Martínez-Avilés,D Wang,J S Francisco,K O Patten,D Youn

doi:10.5194/acp-11-2371-2011

Abstract

Abstract. The existing solvents trichloroethylene (TCE) and perchloroethylene (PCE) and proposed solvent n-propyl bromide (nPB) have atmospheric lifetimes from days to a few months, but contain chlorine or bromine that could affect stratospheric ozone. Several previous studies estimated the Ozone Depletion Potentials (ODPs) for various assumptions of nPB emissions location, but these studies used simplified modeling treatments. The primary purpose of this study is to reevaluate the ODP for n-propyl bromide (nPB) using a current-generation chemistry-transport model of the troposphere and stratosphere. For the first time, ODPs for TCE and PCE are also evaluated in a three-dimensional, global atmospheric chemistry-transport model. Emissions representing industrial use of each compound are incorporated on land surfaces from 30° N to 60° N. The atmospheric chemical lifetime obtained for nPB is 24.7 days, similar to past literature, but the ODP is 0.0049, lower than in our past study of nPB. The derived atmospheric lifetime for TCE is 13.0 days and for PCE is 111 days. The corresponding ODPs are 0.00037 and 0.0050, respectively.

Highlights

1 Introduction n-propyl bromide has been proposed as a potential replacement for compounds that have been used as solvents for many years including trichloroethylene (TCE, chemical formula C2HCl3) and perchloroethylene (PCE, chemical formula C2Cl4, named tetrachloroethylene)
This study considers three VSLSs with a variety of surface fluxes introduced into the MOZART-3 chemistrytransport models of the global atmosphere (CTMs) and a significant range of atmospheric lifetimes
Ozone Depletion Potentials (ODPs) is a measure of relative decrease in global O3 burden, so that we select 1% decrease in global O3 burden arising from each VSLS scenario as that common basis

Summary

Introduction

1 Introduction n-propyl bromide (chemical formula CH3CH2CH2Br, named 1-bromopropane and abbreviated below as nPB) has been proposed as a potential replacement for compounds that have been used as solvents for many years including trichloroethylene (TCE, chemical formula C2HCl3) and perchloroethylene (PCE, chemical formula C2Cl4, named tetrachloroethylene). As discussed in the 2002 World Meteorological Organization international stratospheric ozone assessment (Ko et al, 2003), four modeling studies (Wuebbles et al, 1999, 2001; Bridgeman et al, 2000; Olsen et al, 2000) have previously evaluated Ozone Depletion Potentials (ODPs) for nPB. Bridgeman et al (2000) used the TOMCAT 3-D global chemical-transport model (5.6◦×5.6◦×31 levels) to evaluate the atmospheric lifetime and amount of nPB reaching the stratosphere as a function of location and season of emission. The rest (48%) is from transport of inorganic bromine These studies indicated the potential importance of considering both pathways in deriving the halogen reaching the stratosphere and the resulting ODPs for VSL gases like nPB. For nPB emissions at midlatitudes (North America, Europe, and Asia – roughly 30◦ N to 60◦ N), the modified ODPs range from 0.017 to 0.026

Objectives

Methods

Results

Conclusion