Organic and inorganic gaseous chlorine concentrations in relation to the particle size distribution of chloride in the marine aerosol

Abstract

An intensive field sampling program has been carried out over the ocean in which 56 gas samples and 172 aerosol particle samples were analyzed for total organic chlorine and total inorganic chlorine gas and for particulate chlorine as a function of particle size. Sampling was conducted for 13-to 21-hour periods, March 5-14, 1976, 4 km from the north Florida shore of the Gulf of Mexico at 10-m and 2-m heights.Replicate samples collected simultaneously showed agreement within analytical errors generally of a few percent for gases and for the sum of particle size fractions. Over the course of the experiment, 21 ambient measurements of organic chlorine averaged 3050 ng Cl/m 8 STP of air, with a standard deviation of the distribution of measurements of 80 ng Cl/m 8 STP. Also in 21 measurements the sum of particulate and inorganic chlorine averaged 3030 + 190 ng Cl/m • STP. Thus the total chlorine concentration observed averaged 6070 + 220 ng Cl/m • STP, of which 50% was organic gaseous. In contrast, the proportion of inorganic gaseous chlorine varied drastically, ranging from one half to one hundred times the observed particulate chlorine concentration. The variation depended at least in part on whether cascade impactors with Nuclepore backup filters or filters alone were used for particle sampling before the airstream passed through treated LiOH-impregnated gas absorption filters and charcoal absorbers. The results suggest that rapid interchange occurs between inorganic gaseous and particulate chlorine in the atmosphere but that organic gaseous chlorine is relatively decoupled from these forms.

The impact of the chlorocarbon industry on the ozone layer

“…Their measurements show the organic halogen compounds to be the dominating halogen gases at ground level, chlorine being the most abundant, having a highly variable inorganic component (0.05-0.36 ppbv (parts per billion by volume), average 0.15 ppbv) and a much more constant organic component (0.45-0.9 ppbv, average 0.7 ppbv). Other observational results in the coastal marine atmosphere were obtained by Berg and Winchester [1976], who detected 1.8 ppbv (+3%) organic and 1.2 ppbv (+ 31%) inorganic chlorine.…”

First measurements of total chlorine and bromine in the lower stratosphere

“…On future flights this assumption will actually be checked by measurement. Additional analytical details have been previously reported (Berg, 1976;Berg and Winchester, 1977;Sedlacek et al, 1980). A 907 kg (2000 lb.)…”

“…This cleaning procedure produced charcoal with C1, Br, and I levels below detection by neutron activation analysis. Additional sampling details and techniques have been previously reported (Berg, 1976;Berg and Winchester, 1977). For each sample in the activated charcoal matrix the elemental halogen determination was made by nondestructive neutron activation analysis.…”

“…However, the possibility of C1 and/or Br sample contamination cannot be absolutely ruled out. Sampling procedures have been reported (Berg and Winchester, 1977;Sedlacek et al, 1980). A detailed report on the aircraft and balloon sampling techniques is currently in preparation.…”

“…The total content of organically bound chlorine (CI•) near the earth's surface has been repeatedly measured and found to be below 3 ppbv (Rahn et al, 1976;Berg and Winchester, 1977;Singh et al 1978). This amount of chlorine is in fact very close to the sum of the amounts of organically-bound chlorinated species measured individually in the troposphere.…”