ISSN:
1573-0662
Keywords:
Formic acid
;
carbon-13
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
,
Geosciences
Notes:
Abstract Relatively large quantities (≈1 mg) of formic acid have been collected from the atmosphere and subjected to carbon-isotopic analysis, as a means of source discrimination. Ambient formic acid was captured on Ca(OH)2-treated filters using a high-volume sampler. The collection method was not only efficient (〉96%), but also appears to have low artifact production. Most of the samples (36 out of 52) were collected over a two-year period at the summit of Mount Lemmon, Arizona, where a strong seasonality in HCOOH mixing ratio was observed (≈0.2 ppb during winter months to 1.5 ppb in the summer). Other collection sites included the Oregon coast, Colorado Rockies, urban Tucson, and the North Dakota prairie. The carbon-13 content of atmospheric HCOOH was found to be have little variation (−18 to −25‰), regardless of location or season. This is consistent with a single dominant source of formic acid. The carbon-14 measurements of 6 Mount Lemmon samples showed high levels of modern carbon (93–113% modern). The emissions from formicine ants and automobile combustion were selected as two other potential sources for isotopic analysis. The HCOOH collected from auto exhaust was much more depleted in13C than the atmospheric samples, with a δ13C of −28.0 and −48.6‰ from a leaded and unleaded automobile, respectively. Formicine ants, on the other hand, ranged from −17.2 to −20.6‰.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00702822
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