Observations of Sharp Oxalate Reductions in Stratocumulus Clouds at Variable Altitudes: Organic Acid and Metal Measurements During the 2011 E-PEACE Campaign
Abstract
This work examines organic acid and metal concentrations in northeastern Pacific Ocean stratocumulus cloudwater samples collected by the CIRPAS Twin Otter between July and August 2011. Correlations between a suite of various monocarboxylic and dicarboxylic acid concentrations are consistent with documented aqueous-phase mechanistic relationships leading up to oxalate production. Monocarboxylic and dicarboxylic acids exhibited contrasting spatial profiles reflecting their different sources; the former were higher in concentration near the continent due to fresh organic emissions. Concentrations of sea salt crustal tracer species, oxalate, and malonate were positively correlated with low-level wind speed suggesting that an important route for oxalate and malonate entry in cloudwater is via some combination of association with coarse particles and gaseous precursors emitted from the ocean surface. Three case flights show that oxalate (and no other organic acid) concentrations drop by nearly an order of magnitude relative to samples in the same vicinity. A consistent feature in these cases was an inverse relationship between oxalate and several metals (Fe, Mn, K, Na, Mg, Ca), especially Fe. By means of box model studies we show that the loss of oxalate due to the photolysis of iron oxalato complexes is likely a significant oxalate sink in the study region due to the ubiquity of oxalate precursors, clouds, and metal emissions from ships, the ocean, and continental sources.
Additional Information
© 2013 American Chemical Society. Received: March 22, 2013; Revised: June 12, 2013; Accepted: June 20, 2013; Published: June 20, 2013. This work was funded by ONR grants N00014-10-1-0811, N00014-11-1-0783, and N00014-10-1-0200. We acknowledge Dean Hegg for providing the cloudwater collector. We gratefully acknowledge the NOAA Air Resources Laboratory (ARL) for the provision of the HYSPLIT transport and dispersion model and READY website (http://ready.arl.noaa. gov) used in this publication. BE acknowledges support from NOAA's Climate Goal.Attached Files
Supplemental Material - es4012383_si_001.pdf
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Additional details
- Eprint ID
- 41346
- DOI
- 10.1021/es4012383
- Resolver ID
- CaltechAUTHORS:20130916-132554060
- N00014-10-1-0811
- Office of Naval Research (ONR)
- N00014-11-1-0783
- Office af Naval Research (ONR)
- N00014-10-1-0200
- Office of Naval Research (ONR)
- National Oceanic and Atmospheric Administration (NOAA)
- Created
-
2013-09-16Created from EPrint's datestamp field
- Updated
-
2021-11-10Created from EPrint's last_modified field