The project

Don't go where the road leads, rather go where there is no road and leave a trail. M. Scott Peck

  The project  Analytical Approach

Analytical Approach

analytic

Determination of biomass burning in ice cores

Important compounds from biomass burning include monosaccharide anhydrides (MAs), and the most important tracer compound among them is levoglucosan (1,6-anhydro-β-D-glucopyranose) and to a lesser degree galactosan (1,6-anhydro-β-D-galactopyranose) and mannosan (1,6-anhydro-β-D-mannopyranose). These are specific molecular tracers utilized for the assessment of particulate matter composition from biomass burning in the atmosphere because they cannot be generated by non-combustive processes or by non-wood combustion. Molecular markers such as MAs are important tools in tracking the transport of particles produced by biomass burning. Among them, levoglucosan has been considered an excellent choice because it is emitted in large quantities and is stable in the atmosphere.

Levoglucosan can be precisely determined due to the lack of other compounds that cause interference with the peak identification in the chromatogram. Ultraclean methods are necessary to decontaminate the ice samples from any residual material retained from both the ice core drilling and any subsequent core handling and each stage of sample and container preparation is conducted in a class 100 clean room or under a class 100 clean bench. LDPE bottles or other substances in contact with the inner core are cleaned in accordance with demonstrated ultraclean trace element analysis procedures1,2. The melted ice samples are subject to chromatographic analysis and levoglucosan determination using an Agilent 1100 series HPLC system and an API 4000 triple quadrupole mass spectrometer3. All necessary instrumentation and clean benches for the project are currently available at the University of Venice.

Analysis of other organic markers, trace elements (TEs) and rare earth elements (REEs) in ice cores

The Laboratoire de Glaciologie et Géophysique de l'Environnement in Grenoble, France (LGGE) was one of the first institutions to examine the use of oxalate in polar snow and ice as a proxy for biomass burning2. Our research team used this technique to examine sixty-eight snow pit samples from near Summit, central Greenland (72°20’N; 38°45’W, 3270 m.a.s.l) which were measured using ion chromatography. An oxalate peak that is an order of magnitude higher than neighboring samples conclusively highlights the strong fingerprint of fallout from a biomass burning event from a Canadian origin4 (Figure 6).   

Levoglucosan flux replicates the oxalate measurements in the Summit Greenland snow samples (Figure 6). This reproduction of biomass burning proxies can be used to calibrate the two types of measurements. Oxalate can be produced by multiple pathways including metabolic processes by fungi5 while levoglucosan is a much more specific organic biomarker of burning as it can only be produced by biomass burning and in fires with temperatures above 300°C6.

  Polar organic markers are emitted in different proportions from different types of biomass burning7,8. In these studies, resin acids were found in emissions from pine needle fires and sequoia forest prescribed burn samples. Similarly, research shows that syringaldehyde is abundant in emissions from sagebrush, whereas vanillic acid (conifer-specific biomass burning tracer)7,8 is more abundant in emissions from the pine needles and sequoia grove prescribed burn. We will measure vanillic acid, syringaldehyde, and oxalate in the ice core samples to supplement and enhance the determination of levoglucosan flux.

  In addition, we will quantify trace elements (TEs) and rare earth elements (REEs) in both the ice and lake cores to better constrain the biomass burning history.The determination of TEs and REEs in ice and lake cores aid in understanding the source areas of the biomass burning event itself as plants incorporate REEs (with the exception of Ce) from their environment2,9,10.This preservation of the relative abundance of REEs, and the associated negative Ce anomaly, may provide evidence for a biomass burning event as the ashes deriving from the event are characterized by the same REEs pattern as the soil. By investigating the REEs pattern we can also assume the plant type which created the burned particulate matter2,9,10 We will investigate REEs, TEs, and other organic markers in each sample. A sampling scheme is included in a later section of the proposal.

Determination of biomass burning in sediments

My research group has recently developed a methodology for the determination of levoglucosan in sediment cores which expands the novel technique to another paleoclimate archive. All sample preparation is performed under clean conditions (class 100 clean room or clean bench). Fresh external and internal standards are created using levoglucosan, galactosan and mannosan labeled/marked levoglucosan 13C6  with 98% isotopic enrichment and purity and HPLC/MS grade methanol. The instrumental response, linearity of the response, and the calibration curves are always controlled before the sample analysis. Samples are ground, subject to multiple extractions, and filtered (0.45 μm PTFE filters) under class 100 clean room conditions. Sample analysis is conducted on a HPLC coupled with a quadrupole mass spectrometer (Separation: HPLC with polar C-18    Eluent: water/acetonitrile     Source:ESI    Mass Analyzer: API 4000 MS/MS)

Analysis of other organic markers, trace elements (TEs) and rare earth elements (REEs) in ice cores

The Laboratoire de Glaciologie et Géophysique de l'Environnement in Grenoble, France (LGGE) was one of the first institutions to examine the use of oxalate in polar snow and ice as a proxy for biomass burning2. Our research team used this technique to examine sixty-eight snow pit samples from near Summit, central Greenland (72°20’N; 38°45’W, 3270 m.a.s.l) which were measured using ion chromatography. An oxalate peak that is an order of magnitude higher than neighboring samples conclusively highlights the strong fingerprint of fallout from a biomass burning event from a Canadian origin4 (Figure 6).   

Levoglucosan flux replicates the oxalate measurements in the Summit Greenland snow samples (Figure 6). This reproduction of biomass burning proxies can be used to calibrate the two types of measurements. Oxalate can be produced by multiple pathways including metabolic processes by fungi5 while levoglucosan is a much more specific organic biomarker of burning as it can only be produced by biomass burning and in fires with temperatures above 300°C6.

  Polar organic markers are emitted in different proportions from different types of biomass burning7,8. In these studies, resin acids were found in emissions from pine needle fires and sequoia forest prescribed burn samples. Similarly, research shows that syringaldehyde is abundant in emissions from sagebrush, whereas vanillic acid (conifer-specific biomass burning tracer)7,8 is more abundant in emissions from the pine needles and sequoia grove prescribed burn. We will measure vanillic acid, syringaldehyde, and oxalate in the ice core samples to supplement and enhance the determination of levoglucosan flux.

  In addition, we will quantify trace elements (TEs) and rare earth elements (REEs) in both the ice and lake cores to better constrain the biomass burning history.The determination of TEs and REEs in ice and lake cores aid in understanding the source areas of the biomass burning event itself as plants incorporate REEs (with the exception of Ce) from their environment2,9,10.This preservation of the relative abundance of REEs, and the associated negative Ce anomaly, may provide evidence for a biomass burning event as the ashes deriving from the event are characterized by the same REEs pattern as the soil. By investigating the REEs pattern we can also assume the plant type which created the burned particulate matter2,9,10 We will investigate REEs, TEs, and other organic markers in each sample. A sampling scheme is included in a later section of the proposal.

 

 

Figure 6: Levoglucosan (red) and oxalate (blue) flux determined in Greenland snow (Barbante, unpublished data)

 

 

  1. Gambaro et al. (2008) Analytical Chemistry, v. 80, 1659-1699
  2. Fu et al. (2004) Geochemical Journal, 38, (4) 333-343
  3. Joos et al., (2004) Global Biogeochemical Cycles, 18 (2)
  4. Barbante et al. (2003) Journal of Environmental Monitoring, v. 5, 328-335
  5. Yunker et al. (2002) Organic Geochemistry 33, 489-515
  6. Soloman et al., (2007) IPCC Report 2007: The Physical Science Basis, Cambridge Univ. Press, 996 pp.
  7. Simoneit (2002) Applied Geochemistry, 17, 129-162
  8. Fine et al. (2004) Environmental Engineering Science, 21 (3), 387-409
  9. Aubert et al. (2006) Geochimica et Cosmochimica Acta, 70, 11, 2815-Akagi et al. (2002) Geochemical Journal, 36, (2) 113-118
  10. Harvey et al. (1997) Eds. Polycyclic Aromatic Hydrocarbons; John Wiley & Sons: New York.
  11. Grimalt et al. (2004) Environmental Pollution 131, 13-
  12. Conedera et al., (2008), Quaternary Science Reviews, 28, 555-576
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