1 / 12

Supporting Evidences

Photolysis of Particulate Nitrate: a Daytime HONO Source and a Re-NOx-ification Pathway in the Troposphere ( TROPospheic HONO: TROPHONO ) A Component of NOMADSS (Nitrogen, Oxidants, Mercury, and Aerosol Distributions , Sources and Sinks) Field Campaign

decima
Télécharger la présentation

Supporting Evidences

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Photolysis of Particulate Nitrate: a Daytime HONO Source and a Re-NOx-ification Pathway in the Troposphere (TROPospheic HONO: TROPHONO) A Component of NOMADSS (Nitrogen, Oxidants, Mercury, and Aerosol Distributions,Sources and Sinks) Field Campaign Xianliang Zhou (Wadsworth Center and SUNY Albany) Jochen Stutz (University of California, Los Angeles)

  2. Objective: To investigate the role of particulate nitrate photolysis in the cycling of reactive nitrogen species in the troposphere, focusing on HONO as an intermediate product. Hypothesis 1: Photolysis of particulate nitrate in aerosol particles, and, to a lesser extent, NO2 conversion on organic aerosol, are major sources of HONO in the low-NOx troposphere above the surface boundary layer. Hypothesis 2: Photolysis of particulate nitrate in aerosol particles represents an important pathway to recycle HNO3/nitrate back to photochemically reactive NOx (re-NOx-ification) in the troposphere.

  3. Supporting Evidences • Substantial daytime HONO exists in the upper atmospheric boundary layer and free troposphere  require a strong daytime HONO source in the air column. • Photolysis of particulate nitrate (pNO3) in aerosol is fast, with a lifetime of ~1.4 hr for pNO3, with HONO as a dominant product (HONO/NO2 = 3 - 9)

  4. Potential impact of p-NO3 photolysis on tropospheric photochemistry

  5. 1. Daytime horizontal transects and vertical profiling over land and ocean: To establish daytime distributions of HONO and its production rate, and their relationships with pNO3, NOx, pOrganics, aerosols, and O3 in different air masses. 2. Daytime HONO production in urban plumes: To study daytime HONO production in the urban plumes as a function of photochemical ages, and to establish the maximum HONO contribution from the NOx precursor. 3. Nighttime HONO accumulation/early morning decay: To study nighttime accumulation and morning hour decay of HONO . The HONO formation rates during the day and the night will be compared. 4. Bulk aerosol sampling: To collect aerosol samples for laboratory pNO3 photolysis experiments. Flight Strategy/Experimental Designs

  6. horizontal transects and vertical profiles *

  7. HONO system • Aqueous scrubbing • Azo dye derivatization • Long-Path Absorption Photometric (LPAP) detection of azo dye • Detection limit ~1 pptv • 90% response time ~1 min

  8. HONO system Ambient air Valve/sampler box MFC MFC Relays Relays SA/NED H2O SA/NED H2O

  9. HONO data from two HONO systems

  10. HNO3system • Aqueous scrubbing • NO3- to NO2- conversion on Cd-reductor • Azo dye derivatization • Long-Path Absorption Photometric (LPAP) detection of azo dye • Detection limit ~20 pptv • 90% response time ~1 min Ambient air Valve/sampler box MFC Relays Cdreductor NH4Cl buffer SA/NED

  11. PNO3system • Aqueous scrubbing • NO3- to NO2- conversion on Cd-reductor • Azo dye derivatization • Long-Path Absorption Photometric (LPAP) detection of azo dye • Detection limit ~20 pptv • 90% response time ~1 min Ambient air Valve/sampler box MFC Relays NH4Cl buffer Cdreductor SA/NED

  12. P-Organics system • Aqueous scrubbing • Long-Path Absorption measurement a 300 nm Valve/sampler box Ambient air MFC Relays H2O/AcN

More Related