Isotopic Characterization of Carbonaceous Aerosols

Abstract

Carbonaceous aerosol samples were collected during numerous field experiments either in continental or oceanic areas in the two hemispheres. An experimental procedure has been optimized for the collection, concentration analysis, and isotopic composition determination (¹³C / ¹²C) by mass spectrometry of size-segregated samples. Data is presented here on the characteristic isotopic composition and isotopic variability of the main sources of atmospheric particulate carbon. Such an approach allows the differentiation between not only marine and continental material but also between continental natural and anthropogenic matter among these aerosols. Particularly, combustion of the vegetation induces a large isotopic separation between the two isotopes and, consequently, the aerosol which is emitted is characteristically depleted in ¹³C. The isotopic tool is used here for the first time to assess the origin of carbonaceous aerosols whatever the environment. The areal and temporal isotopic variabilities of aerosol samples are shown to be related to the diversity of the sources, and also to the proper temporal variability of the intensity and the isotopic composition of these sources. Far from the source regions, carbonaceous aerosols bear their isotopic characteristics; the isotopic tool appears to be a promising tracer of the bulk atmospheric particulate carbon.