Application of the ECT9 protocol for radiocarbon-based source apportionment of carbonaceous aerosols

Abstract. Carbonaceous aerosol is mainly composed of organic carbon (OC) and elemental (EC). Both OC EC originate from a variety emission sources. Radiocarbon (14C) analysis can be used to apportion bulk aerosol, OC, into their However, such analyses require the physical separation EC. Here, we apply ECT9 protocol physically isolate for 14C evaluate its effectiveness. Several reference materials are selected, including two pure (fossil “adipic acid” contemporary “sucrose”), “regal black” “C1150”), three complex containing and/or fossil (“rice char”, NIST urban dust standards “SRM1649a” “SRM8785”, i.e., fine fraction resuspended SRM1649a on filters). The were measured EC, total (TC) mass fractions corresponding isotopes uncertainty procedure. average accuracy TC mass, determined via volumetric injection sucrose solution, was approximately 5 %. Ratios EC/TC OC/TC highly reproducible, with analytical precisions better than 2 % all materials, ranging in size 20 100 µg C. Consensus values reached both ?13C modern (F14C), an < 0.3 ‰ %, respectively. procedure introduced 1.3 ± 0.6 extraneous carbon, amount compatible that Swiss_4S protocol. In addition, isolated mixtures (sucrose) (regal black) (adipic acid) (rice char EC) effectiveness separation. F14C (? 5–30 µg) 10–60 ? average. We found efficiently isolates or mixtures. Based measurements, contribution charred likely less 3 when loading 30 Charring further assessed by evaluating thermograms various samples collected Arctic tailpipes gasoline diesel engines. These data demonstrate method effectively removes pyrolyzed OC. Thus, protocol, initially developed concentration stable isotope measurements suitable 14C-based apportionment studies, C-sized arctic environments.