Fairbanks North Star Borough Modeling Symposium Rick Peltier University of Massachusetts White Paper & Pilot Studies: Winter 2011

2 Fairbanks North Star Borough Modeling Symposium The Plan  Intro on (typical) aerosol formation processes  Relate-ability to FNSB community  Unresolved/open questions  A brief peek at some pilot data from Feb/Mar 2011  Next steps

3 Fairbanks North Star Borough Modeling Symposium Known knowns.  Aerosol can (and does) form in Fairbanks in extreme environments (cold, no water or sun, etc.)  PM concentration in Fairbanks greatly exceed NAAQS, with most exceedances in the winter.  There is a peculiar amount of sulfur in Fairbanks.  PM is comprised (mainly) of ammonium sulfate, organic and elemental carbon, plus a few others.  Other studies (e.g. U Montana) have emphasized the importance of biomass burning.

4 Fairbanks North Star Borough Modeling Symposium Known unknowns.  Aerosol formation processes thought to represent the ‘normal’ formation mechanisms don’t seem to fit the profile in Fairbanks.  What’s with all of this sulfur?  Organics are most of the winter-time PM; where is it coming from? Only biomass? Or on-road? Or home heating oil?

5 Fairbanks North Star Borough Modeling Symposium Aerosol formation  Aerosol forms in one of the following ways: Direct emissions (primary) Indirect formation (secondary) Homogeneous Heterogeneous

6 Fairbanks North Star Borough Modeling Symposium Particle growth (to significant concentrations)  Once formed, particles often continue their growth. Collision (smaller particles) Agglomeration (larger particles) Condensation (all particles)

7 Fairbanks North Star Borough Modeling Symposium And how is this important to Fairbanks?  Direct emissions mainly from woodburning, and perhaps some from oil/diesel combustion. Can this be discerned?  Homogeneous formation possible from power plant emissions – but parameters not well understood.  Heterogeneous formation likely – but who is the dance partner in this chemistry?

8 Fairbanks North Star Borough Modeling Symposium The Missing Ingredient? Oxidant component Likely Local Source of oxidant in Fairbanks Estimated relative reaction efficiency in Fairbanks winter Consideration of future measurement to better understand sulfur conversion? Ozone Photochemical production of ozone low Perhaps. Easy to do with instrumentation already in place. Hydrogen peroxide Mainly found dissolved in clouds/fog resulting from photochemistry Unknown, likely moderate yes Organic Peroxides VOC oxidation due to NO3 radical chemistry low Yes, surveys of representative organic peroxides might yield important information on sulfur conversion pathway. Dissolved OxygenNaturally-occurringProbably trivial No, yield not likely to be significant and O2 concentration already known. Metal catalysis (Fe 3+, Cu 2+, and Mn 2+ ) Direct emission of metals Unknown, possible synergy in presence of both metals. Yes, but these metals already measured in speciation network; consider additional study of metal oxidation states. Hydroxyl radical Photochemical production from water vapor/droplets/crystals Probably low No, technically challenging to directly measure OH Oxides of nitrogenDirect emissionLow Yes, despite low theoretical yield, research infrastructure already in place by investigators at UAF. Also, many local sources, especially in winter. Formaldehyde (and other aldehydes) Direct emission and secondary formation from VOC oxidation unknownYes

9 Fairbanks North Star Borough Modeling Symposium So some of the open questions…  To what degree does wintertime ice fog play a role in secondary aerosol chemistry?  Can the current emissions inventory of sulfur account for the observed sulfur (as sulfate or non-sulfate sulfur-containing components?)  Can PM be better apportioned to on-road diesel, home heating fuel oil, home heating biomass, and coal-fired power plant emissions, which likely comprise the bulk of PM emissions in Fairbanks?

10 Fairbanks North Star Borough Modeling Symposium (and a few more)  How does extreme cold temperatures influence gas-to-particle conversion in the context of stack emissions (e.g. how does a rapidly cooling wet emissions stack perform)?  Can existing (or new) air quality models be better calibrated to on-the-ground observations? Are these model assumptions valid?

11 Fairbanks North Star Borough Modeling Symposium What about this sulfur?  As discussed, ~10-20% excess sulfur by XRF compared to sulfate (most common form of sulfur in aerosol) Method dispute? Not likely Systematic contamination? Probably not. Preferential denuder penetration on XRF filter channel? Could be, J Turner to discuss. Organosulfur? That would be a good bet.

12 Fairbanks North Star Borough Modeling Symposium FNSB Samples

13 Fairbanks North Star Borough Modeling Symposium Aerosol pH in Fairbanks

14 Fairbanks North Star Borough Modeling Symposium Winter 2011 Pilot Investigation  Augment measurement capacity of FNSB to take a broad survey of aerosol climatology.  Instrumentation includes: Hourly measurements of OC and EC Hourly measurements of water-soluble ions Hourly measurements of water-soluble organics Daily XRF of 40+ metals.  All located at Grassy Knoll, Feb to mid-Mar, 2011.

15 Fairbanks North Star Borough Modeling Symposium Status Update  700+ valid aqueous samples – contract in progress, on analyzers now.  80 filter samples (daily pairs) – sent for XRF analysis  EC & OC data at Level Zero validation – show and tell on deck.

16 Fairbanks North Star Borough Modeling Symposium Elemental and Organic Carbon

17 Fairbanks North Star Borough Modeling Symposium A Closer Look  Peculiar diurnal profile apparent in both EC and OC.  Ratio quite high for ‘typical’ urban environments. High even for biomass burning.  No significant diurnal variation.

18 Fairbanks North Star Borough Modeling Symposium What does this mean?  OC and EC are significant influences for Fairbanks – OC (by itself) routinely comprises NAAQS; note no correction to OM.  EC and OC trend extremely well; likely co- emitted.  Most likely from wood and fuel oil combustion; if organosulfur, then probably from fuel oil.  Ion analysis is progress.

19 Fairbanks North Star Borough Modeling Symposium The Next Steps?  Lots of open questions – looking to this Symposium to provide some additional direction.  Consider both short term and long term approaches Short term = answer those immediate mechanism questions; long term = does the chemistry change.  Another round of targeted field studies? If so, prep time is now.

20 Fairbanks North Star Borough Modeling Symposium Summary  Fairbanks does not have textbook atmospheric chemistry; typical measurement approaches won’t work (or at least they won’t provide the results we need).  None of the unknowns have to be unknown.  Sulfur is a significant source; probably linked somewhat to oil burning.  Organics are driving much of the local chemistry – need better characterization to identify source(s).

21 Fairbanks North Star Borough Modeling Symposium Acknowledgements  “…Broken box spilled into snow, no vials broken, retrieved and dried each one, and loaded onto carosel…” – 2/27/2011  Fairbanks North Star Borough (and others) for financial support.

22 Fairbanks North Star Borough Modeling Symposium

23 Fairbanks North Star Borough Modeling Symposium Geek Musings  Would our understanding be improved with a Lagrangian study?  Ice fog seems oddly interesting for study – what’s going on in/on/near these crystals?  How does snow chemistry (e.g. halides) affect particle formation?  Given the odd temporal variability (e.g. OC), how concentrations change spatially?  Lots of periodical (and sporadic) studies out there on prescribed burning, and there appears to be a lot of similar burning in FNSB. Worth combing through that data for better tracers? Does the Omni data help?  To what degree do on-road emissions influence the milieu?