Radiocarbon Measurements of Particulates in Smog

Abstract

In recent years in California, smog aerosols have been observed in metropolitan and rural areas. We wondered what the relative contribution is from sources such as fossil fuel combustion (eg, cars, factories) and emissions from trees and other plants. Pollution produced by fossil fuel combustion can be distinguished from biological sources using radioactive carbon. Carbon in fossil organic materials is radioactively dead whereas carbon in living plants contains 14C. Smog particles were collected on clean glass or quartz fiber paper and analyzed in a small volume CO2 proportional counter for 14C content. Results are given for sampling locations at UCLA, El Monte, Riverside, and Lake Tahoe showing the relative contributions of fossil and modern carbon sources ranging from 0 to 74% and 26 to 100% respectively.

Radiocarbon Concentration of California Aerosols

“…By assaying TSP samples for radiocarbon, it is possible to calculate the fossil and contemporary carbon contributions to the aerosol particles and thus determine their origin (Lodge, Bien & Suess, 1960). The TSP collection and isotopic assay methods were described earlier by Berger, Johnson and Holmes (1983). The biospheric data were normalized against the 14C levels in the prevailing atmosphere (Berger et al, Ins;Levin et al, 1985).…”

Accelerator mass spectrometric determination of carbon-14 in the low-polarity organic fraction of atmospheric particles

“…In recent years, radiocarbon (14C) has become widely accepted as an atmospheric tracer of biogenic emissions and biomass combustion products (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14). Radiocarbon is present at known, approximately steady-state levels in all living materials.…”

“…Radiocarbon analysis was first applied to the source apportionment of atmospheric particles in 1955 by Clayton and co-workers (15) and again in 1960 by Lodge et al (16), but the need for very large samples (grams) discouraged further application of the method until more sensitive analytical techniques became available. The development of miniature, well-shielded counters (17,18) made possible radiocarbon measurements of samples containing as little as 5 mg of carbon (19) and led to a resurgence of interest in radiocarbon as an atmospheric tracer (1)(2)(3)13,20,21).…”