Publication Date:
2022-05-26
Description:
Author Posting. © American Geophysical Union, 2012. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 117 (2012): D13303, doi:10.1029/2011JD017153.
Description:
Carbon isotopic signatures (δ13C, Δ14C) of aerosol particulate matter total organic carbon (TOC) and operationally defined organic carbon (OC) components were measured in samples from two background sites in the eastern U.S. TOC and water-soluble OC (WSOC) δ13C values (−27 to −24‰) indicated predominantly terrestrial C3 plant and fossil derived sources. Total solvent extracts (TSE) and their aliphatic, aromatic, and polar OC components were depleted in δ13C (−30 to −26‰) relative to TOC and WSOC. Δ14C signatures of aerosol TOC and TSE (−476 to +25‰) suggest variable fossil contributions (~5–50%) to these components. Aliphatic OC while comprising a small portion of the TOC (〈1%), was dominated by fossil-derived carbon (86 ± 3%), indicating its potential utility as a tracer for fossil aerosol OC inputs. In contrast, aromatic OC contributions (〈1.5%) contained approximately equal portions contemporary (52 ± 8%) and fossil (48 ± 8%) OC. The quantitatively significant polar OC fraction (6–25% of TOC) had fossil contributions (30 ± 12%) similar to TOC (26 ± 7%) and TSE (28 ± 9%). Thus, much of both of the fossil and contemporary OC is deduced to be oxidized, polar material. Aerosol WSOC consistently showed low fossil content (〈8%) relative to the TOC (5–50%) indicating that the majority of fossil OC in aerosol particulates is insoluble. Therefore, on the basis of solubility and polarity, aerosols are predicted to partition differently once deposited to watersheds, and these chemically distinct components are predicted to contribute in quantitatively and qualitatively different ways to watershed carbon biogeochemistry and cycling.
Description:
ASW was partially supported by a Graduate
Fellowship from the Hudson River Foundation during the course of this
study. Additional funding for this work came from a NOSAMS student
internship award, a fellowship award from Sun Trust Bank administered
through the VIMS Foundation, a student research grant from VIMS, and
the following NSF awards: DEB Ecosystems grant DEB-0234533, Chemical
Oceanography grant OCE-0327423, and Integrated Carbon Cycle
Research Program grant EAR-0403949 to JEB; and Chemical Oceanography
grant OCE-0727575 to RMD and JEB.
Description:
2013-01-04
Keywords:
Aerosols
;
Isotopes
;
Organic carbon
;
Particulate matter
;
Radiocarbon
;
Water soluble organic carbon
Repository Name:
Woods Hole Open Access Server
Type:
Article
Format:
text/plain
Format:
application/msword
Format:
application/pdf
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