Slide 1*
On the relationship between nitryl chloride (ClNO2) and molecular chlorine (Cl2) in coastal California
Joel Thornton and Theran Riedel
Department of Atmospheric Sciences
Platt, et al ACP 2004
Allan, et al JGR 2007
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Cl2 (molecular chlorine)
BrCl + Cl-(aq) Cl2 + Br-(aq)
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HOCl(aq) + H+ + Cl- Cl2(g) + H2O
HOCl(aq) + H+ + Br- BrCl(g) + H2O
HOBr(aq) + H+ + Cl- BrCl(g) + H2O
Vogt, et al Nature 1996
Platt, et al ACP 2004
Cl
HCl
ClO
HOCl
O3
CH4
HO2
NO2 + NO3
V. Faye McNeill
James P. Kercher
Theran P. Riedel
(UW Graduate Student)
I- + Cl2 I-Cl2-
From: Thornton, et al. Nature 2010
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Atomic Cl has a large oxidizing potential (10-100x OH)
Cl atoms have potential to substantially affect O3, VOC, and Hg levels.
Cl atom sources are uncertain, but Cl2 has typically been considered the major Cl atom source in polluted regions
Pechtl and von Glasow. GRL, 2007
Knipping and Dabdub. ES&T, 2003
Spicer et al. Nature 394, 1998.
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From: Thornton, et al. Nature 464, 2010
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Los Angeles, CA
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Spicer et al. at Long Island, NY, June 1996.
Finley and Saltzman at La Jolla, CA, January 2006.
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CalNex observations
Full time series. After we left the LA area levels of ClNO2 and Cl2 were low, so our analysis likely won’t involve the final week.
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Santa Monica Bay
Zoom in on major day. We never were able observe the build up of ClNO2. This could be due to ClNO2 formation elsewhere (inland) and transport of that air mass. OR just that we were never lucky enough to be in the az place at the right time. ClNO2 and Cl2 are well correlated on these two days, but as you’ll see this is not always the case.
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Scatter Cl2 vs ClNO2 by day. Some days well correlated, other days not so much. If the major source of Cl2 was ClNO2 these should be well correlated. However, for certain periods there is little to no correlation, indicating a complex heterogeneous relationships.
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Cl atom production: ClNO2 vs. Cl2
Cl atom production from ClNO2 and Cl2 as a whole throughout the entire measurement campaign. The gap in the Cl2 data is a result of filtering daytime Cl2. We are still in the process of working up the Cl2 measurements.
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Our observations consistent with substantial inland production of Cl atom precursors transported to marine environments along with continued production off shore.
ClNO2 should be considered a Cl atom precursor with at least similar importance to Cl2.
Measurements of N2O5 and aerosol composition, mixing, play important roles given the heterogeneous reaction mechanism at work.
Atlantis
ClNO2 production efficiencies
ClNO2 yield predictions
Utilize HCl measurements
Box modeling Cl activation and Cl atom chemistry
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Probably won’t show…
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