Organic enrichment of sea spray aerosols: from the air-water interface to spray generation
EMSL Project ID
49300
Abstract
This proposal describes coupled studies intended to identify and quantify the origin of organic solutes in sea spray aerosols (SSA) and to predict the consequences of aerosol organic enrichment on cloud condensation, cloud brightness and atmospheric reactivity. Surface specific vibrational sum frequency generation (VSFG) spectroscopy will characterize the composition and organization of organic species at planar water/air interfaces where the aqueous phase will be controlled to mimic natural ocean pH and ionic strength. Aerosols will be created from these surfaces using newly developed instrumentation designed to simulate wave breaking action. Aerosols will be trapped and analyzed for total organic carbon as well as speciation using nanospray desorption electrospray ionization-high resolution mass spectrometry (nanospray DESI-HRMS). Results will be integrated into the evolving Accelerated Climate Model for Energy developed at PNNL as a part of the DOE's Climate and Environmental Sciences Division. Motivating these studies are questions about how SSA contain up to 75% organic content by mass. Field measurements imply that much of the SSA organic material consists of soluble saccharides and polysaccharides that should not have strong affinity for the water surface. Our hypothesis is that these soluble species are drawn to the water/air interface through a cooperative adsorption mechanism where noncovalent interactions between solutes and an insoluble monolayer enrich surface organic concentrations. Furthermore, we propose that aerosol formation processes transfer these soluble and insoluble surface species directly into SSAs. Testing these hypotheses requires quantitative measurements capable of resolving molecular-level details about the composition of heterogeneous interfaces and the aerosols formed at those interfaces. From such data will come adsorption energies, surface concentrations and organization of interfacial species. These quantities are critical for development and refinement of predictive climate models.
Facilities required for these studies, including computational resources, are collocated only at EMSL. Furthermore, EMSL scientists have developed unique measurement capabilities that will provide the necessary resolution and sensitivity required to understand adsorption and mass transfer in heterogeneous, complex environmental systems. Experiments will focus on cooperative adsorption induced by lipid monolayers on the surface of solutions containing different mono- and polysaccharides commonly found in ocean waters. Dipalmitoyl phosphocholine (DPPC) will serve as the model lipid in these studies. Glucosamine (GA) and glucuronic acid (GU) -- monomers of the biopolymers chitosan and alginate, respectively -- will serve as representative saccharides. VSFG experiments using EMSL's high resolution, broadband spectrometer will characterize surface coverage and GA/GU enrichment at water interfaces covered with DPPC. Nanospray DESI-HRMS measurements of aerosol particles created from these samples will test whether organic content observed at the water/air interface transfers directly into the gas phase. Results will be used to parameterize and refine climate model simulations being performed by scientists in PNNL's Atmospheric Sciences and Global Change Division.
The proposed work builds upon a nascent collaboration between PI's that demonstrated the potential for cooperative adsorption to enrich of organic species at the water-air interface, but the link between interfacial content and aerosol composition has yet to be demonstrated.
Project Details
Project type
Large-Scale EMSL Research
Start Date
2016-10-01
End Date
2019-09-30
Status
Closed
Released Data Link
Team
Principal Investigator
Co-Investigator(s)
Team Members
Related Publications
Fu Y., Y. Zhang, F. Zhang, J. Chen, Z. Zhu, and X. Yu. 2018. "Does interfacial photochemistry play a role in the photolysis of pyruvic acid in water?." Atmospheric Environment 191. PNNL-SA-137894. doi:10.1016/j.atmosenv.2018.07.061
Link, KA. Cooperative adsorption in model sea spray aerosols with vibrational sum frequency generation. Pacific Conference on Spectroscopy and Dynamics, San Diego, CA, January 26, 2018.
Link, KA. Cooperative adsorption in model sea spray aerosols with vibrational sum frequency generation. Tohoku Universitys Chemistry Summer School, Sendai, Japan, August 22, 2017.
McCluskey, C. (2017). EVIDENCE FOR A BIOLOGICAL CONTROL ON EMISSIONS OF MARINE ICE NUCLEATING PARTICLES: LABORATORY, FIELD AND MODELING RESULTS. Ph.D. Dissertation, Colorado State University.
Mccluskey C.S., P.J. DeMott, P. Ma, and S.M. Burrows. 2019. "Numerical Representations of Marine Ice Nucleating Particles in Remote Marine Environments Evaluated against Observations." Geophysical Research Letters 46, no. 13:7838-7847. PNNL-SA-140385. doi:10.1029/2018GL081861
McCluskey et al., Marine Ice Nucleating Particles: Observations and Modeling Studies, University of Washington Cloud and Climate Discussion Group, January 9, 2018.
Zhang F., X. Yu, J. Chen, Z. Zhu, and X. Yu. 2019. "Dark air-liquid interfacial chemistry of glyoxal and hydrogen peroxide." Nature Climate and Atmospheric Science. PNNL-SA-146695. doi:10.1038/s41612-019-0085-5