Understanding chemistry behind secondary aerosol production from nitrogen and sulfur compounds from agriculture

Authors: Silva, Philip - Phil; VAN ROOY, PAUL - University Of California; PURVIS-ROBERTS, KATHLEEN - Claremont Colleges; NEE, MATTHEW - Western Kentucky University; COCKER III, DAVID - University Of California

Submitted to: Air and Waste Management Annual Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 2/2/2017
Publication Date: 6/7/2017
Citation: Silva, P.J., Van Rooy, P., Purvis-Roberts, K., Nee, M., Cocker Iii, D.R. 2017. Understanding chemistry behind secondary aerosol production from nitrogen and sulfur compounds from agriculture. Air and Waste Management Annual Conference Proceedings. Paper No. 264152.

Interpretive Summary:

Technical Abstract: Agricultural emissions impact particulate mass concentrations through both primary and secondary processes. Evidence from laboratory and field work suggest that not only does ammonia produce secondary particulate matter, but nitrogen and sulfur containing volatile organic compounds also contribute. Here we discuss results from some smog chamber experiments focused on atmospheric chemistry of nitrogen and sulfur compounds and their potential for secondary aerosol formation. Nitrogen-containing compounds studied include ammonia, trimethylamine, diethylamine, and butylamine. Sulfur compounds under study include hydrogen sulfide, methanethiol, dimethylsulfide, and dimethyldisulfide. Laboratory results suggest that rapid formation of secondary aerosol in airmasses containing both reduced nitrogen and reduced sulfur compounds can occur. There are two competing mechanisms of particle formation: 1) acid-base reaction chemistry due to basic nitrogen compounds reacting with oxidized sulfur (sulfate) and 2) photochemical formation of oxidized organic compounds from photolysis of both nitrogen and sulfur compounds. Experimental data suggest the photochemical formation pathway is important at lower humidities while the acid-base pathway dominates at higher ones. The implications here are that these reactions may be important and overlooked in accounting for particle mass concentration loadings, particularly in rural locations influenced by agricultural emissions.