Concentrations and biosphere-atmosphere fluxes of inorganic trace gases and associated ionic aerosol counterparts over the Amazon rainforest

Author(s):Show less -

Ramsay, Robbie ^{[1, 2, 3]} ; Di Marco, Chiara F. ^[1] ; Soergel, Matthias ^{[4, 5]} ; Heal, Mathew R. ^[2] ; Carbone, Samara ^[6] ; Artaxo, Paulo ^[7] ; de Araujo, Alessandro C. ^[8] ; Sa, Marta ^[9] ; Poehlker, Christopher ^[5] ; Lavric, Jost ^[10] ; Andreae, Meinrat O. ^{[4, 11]} ; Nemitz, Eiko ^[1]

Affiliation:Show less -

^[1] UK Ctr Ecol & Hydrol UKCEH, Bush Estate, Penicuik EH26 0QB, Midlothian - Scotland

^[2] Univ Edinburgh, Sch Chem, Joseph Black Bldg, David Brewster Rd, Edinburgh EH9 3FJ, Midlothian - Scotland

^[3] NERC Field Spect Facil, James Hutton Rd, Edinburgh EH9 3FE, Midlothian - Scotland

^[4] Max Planck Inst Chem, Biogeochem Dept, D-55128 Mainz - Germany

^[5] Max Planck Inst Chem, Atmospher Chem Dept, Mainz - Germany

^[6] Univ Fed Uberlandia, Agr Sci Inst, Uberlandia, MG - Brazil

^[7] Univ Sao Paulo, Inst Fis, Sao Paulo - Brazil

^[8] Empresa Brasileira Pesquisa Agr EMBRAPA, BR-66095100 Belem, Para - Brazil

^[9] Inst Nacl Pesquisas Amazonia INPA, Large Scale Biosphere Atmosphere Expt Amazonia LB, BR-69067375 Manaus, Amazonas - Brazil

^[10] Max Planck Inst Biogeochem, Dept Biogeochem Syst, Jena - Germany

^[11] Univ Calif San Diego, Scripps Inst Oceanog, La Jolla, CA 92093 - USA

• Document type: Journal article
• Source: Atmospheric Chemistry and Physics; v. 20, n. 24, p. 15551-15584, DEC 15 2020.
• Web of Science Citations: 0

Abstract

The Amazon rainforest presents a unique, natural laboratory for the study of surfaceatmosphere interactions. Its alternation between a near-pristine marine-influenced atmosphere during the wet season and a vulnerable system affected by periodic intrusions of anthropogenic pollution during the dry season provides an opportunity to investigate some fundamental aspects of boundary-layer chemical processes. This study presents the first simultaneous hourly measurements of concentrations, fluxes, and deposition velocities of the inorganic trace gases NH3, HCl, HONO, HNO3, and SO2 as well as their water-soluble aerosol counterparts NH4+, Cl-, NO2-, NO3- and SO42- over the Amazon. Species concentrations were measured in the dry season (from 6 October to 5 November 2017), at the Amazon Tall Tower Observatory (ATTO) in Brazil, using a two-point gradient wet-chemistry instrument (GRadient of AErosols and Gases Online Registration, GRAEGOR) sampling at 42 and 60 m. Fluxes and deposition velocities were derived from the concentration gradients using a modified form of the aerodynamic gradient method corrected for measurement within the roughness sub-layer. Findings from this campaign include observations of elevated concentrations of NH3 and SO2 partially driven by long-range transport (LRT) episodes of pollution and the substantial influence of coarse Cl- and NO3- particulate on overall aerosol mass burdens. From the flux measurements, the dry season budget of total reactive nitrogen dry deposition at the ATTO site was estimated as -2.9 kg N ha(-1)a(-1). HNO3 and HCl were deposited continuously at a rate close to the aerodynamic limit. SO2 was deposited with an average daytime surface resistance (R-c) of 28 s m(-1), whilst aerosol components showed average surface deposition velocities of 2.8 and 2.7 mm s(-1) for SO42- and NH4+, respectively. Deposition rates of NO3- and Cl- were higher at 7.1 and 7.8 mm s(-1), respectively, reflecting their larger average size. The exchange of NH3 and HONO was bidirectional, with NH3 showing emission episodes in the afternoon and HONO in the early morning hours. This work provides a unique dataset to test and improve dry deposition schemes for these compounds for tropical rainforest, which have typically been developed by interpolation from conditions in temperate environments. A future campaign should focus on making similar measurements in the wet season in order to provide a complete view of the annual pattern of inorganic trace gas and coarse aerosol biosphere-yatmosphere exchange over tropical rainforest. (AU)

• FAPESP's process: 17/17047-0 - Aerosol and clouds life cycles in Amazonia: biogenic emissions, biomass burning and impacts on ecosystem
• Grantee: Paulo Eduardo Artaxo Netto
• Support Opportunities: Research Program on Global Climate Change - Thematic Grants