22 research outputs found
Examining Interdisciplinary Sustainability Institutes at Major Research Universities: Innovations in Cross-Campus + Cross-Disciplinary Models
This is a study of the distinctive characteristics, activities, challenges and opportunities of a specific type of sustainability institute, one that spans the many disciplines of the university and, to do so, reports to upper administration (provost or vice president of research). Among research universities within the Association of American Universities (AAU), 19 were identified, and 18 agreed to participate in this study. Directors are sent a 71-question survey in January 2017 that covered issues of Governance, Research, Education, Engagement, Campus Operations and Best Practices
Phytoplankton blooms weakly influence the cloud forming ability of sea spray aerosol
After many field studies, the establishment of connections between marine microbiological processes, sea spray aerosol (SSA) composition, and cloud condensation nuclei (CCN) has remained an elusive challenge. In this study, we induced algae blooms to probe how complex changes in seawater composition impact the ability of nascent SSA to act as CCN, quantified by using the apparent hygroscopicity parameter (Îșapp). Throughout all blooms, Îșapp ranged between 0.7 and 1.4 (average 0.95â±â0.15), consistent with laboratory investigations using algaeâproduced organic matter, but differing from climate model parameterizations and in situ SSA generation studies. The size distribution of nascent SSA dictates that changes in Îșapp associated with biological processing induce less than 3% change in expected CCN concentrations for typical marine cloud supersaturations. The insignificant effect of hygroscopicity on CCN concentrations suggests that the SSA production flux and/or secondary aerosol chemistry may be more important factors linking ocean biogeochemistry and marine clouds.Key PointsChanges in seawater and sea spray composition did not strongly affect expected CCN concentrationsBlooms may impact clouds more strongly through changes in aerosol flux or secondary chemistryModel parameterizations likely overestimate changes in cloud nuclei due to primary marine organicsPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/134444/1/grl54978_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/134444/2/grl54978-sup-0001-supinfo.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/134444/3/grl54978.pd
Changes in precipitating snow chemistry with location and elevation in the California Sierra Nevada
Orographic snowfall in the Sierra Nevada Mountains is an important source of water for California and can vary significantly on an annual basis. The microphysical properties of orographic clouds and subsequent formation of precipitation are impacted, in part, by aerosols of varying size, number, and chemical composition, which are incorporated into clouds formed along the Sierra barrier. Herein, the physicochemical properties and sources of insoluble residues and soluble ions found in precipitation samples were explored for three sites of variable elevation in the Sierra Nevada during the 2012â2013 winter season. Residues were characterized using a suite of physicochemical techniques to determine the sizeâresolved number concentrations and associated chemical composition. A transition in the aerosol sources that served as cloud seeds or were scavenged inâcloud and belowâcloud was observed as a function of location and elevation. Anthropogenic influence from the Central Valley was dominant at the two lowest elevation sites (1900 and 2200âm above mean sea level (AMSL)), whereas longârange transported mineral dust was a larger contributor at the highest elevation site where cleaner conditions were observed (2600âm AMSL). The residues and soluble ions observed provide insight into how multiple aerosol sources can impact cloud and precipitation formation processes, even over relatively small spatial scales. The transition with increasing elevation to aerosols that serve as ice nucleating particles may impact the properties and extent of snowfall in remote mountain regions where snowpack provides a vital supply of water.Key PointsPhysiochemical properties of particles found in precipitation were determinedBoth anthropogenic and natural sources contributed to the snow residue chemistrySnow residue sources varied depending on location and elevationPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/133563/1/jgrd53083-sup-0001-SI.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/133563/2/jgrd53083_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/133563/3/jgrd53083.pd
Gas-Phase Water Mediated Equilibrium Study Between Methylglyoxal and its Geminal Diol
In aqueous solution, aldehydes, and to a lesser extent ketones, hydrate to form geminal diols. We investigate the hydration of methylglyoxal (MG) in the gas phase, a process not previously considered to occur in water-restricted environments. In this study, we spectroscopically identified methylglyoxal diol (MGD) and obtained the gas-phase partial pressures of MG and MGD. These results, in conjunction with the relative humidity, were used to obtain the equilibrium constant, KP, for the water-mediated hydration of MG in the gas phase. The Gibbs free energy for this process, ÎG°, obtained as a result, suggests a larger than expected gas-phase diol concentration. This may have significant implications for understanding the role of organics in atmospheric chemistry
Factors controlling the transfer of biogenic organic species from seawater to sea spray aerosol.
Ocean waves transfer sea spray aerosol (SSA) to the atmosphere, and these SSA particles can be enriched in organic matter relative to salts compared to seawater ratios. A fundamental understanding of the factors controlling the transfer of biogenic organic matter from the ocean to the atmosphere remains elusive. Field studies that focus on understanding the connection between organic species in seawater and SSA are complicated by the numerous processes and sources affecting the composition of aerosols in the marine environment. Here, an isolated ocean-atmosphere system enables direct measurements of the sea-air transfer of different classes of biogenic organic matter over the course of two phytoplankton blooms. By measuring excitation-emission matrices of bulk seawater, the sea surface microlayer, and SSA, we investigate time series of the transfer of fluorescent species including chlorophyll-a, protein-like substances, and humic-like substances. Herein, we show the emergence of different molecular classes in SSA at specific times over the course of a phytoplankton bloom, suggesting that SSA chemical composition changes over time in response to changing ocean biological conditions. We compare the temporal behaviors for the transfer of each component, and discuss the factors contributing to differences in transfer between phases
Spectroscopic Determination of Aerosol pH from AcidâBase Equilibria in Inorganic, Organic, and Mixed Systems
Atmospheric
aerosol acidity impacts key multiphase processes, such
as acid-catalyzed reactions leading to secondary organic aerosol formation,
which impact climate and human health. However, traditional indirect
methods of estimating aerosol pH often disagree with thermodynamic
model predictions, resulting in aerosol acidity still being poorly
understood in the atmosphere. Herein, a recently developed method
coupling Raman microspectroscopy with extended DebyeâHuÌckel
activity calculations to directly determine the acidity of individual
particles (1â15 ÎŒm
projected area diameter, average 6 ÎŒm) was applied to a range
of atmospherically relevant inorganic and organic acidâbase
equilibria systems (HNO<sub>3</sub>/NO<sub>3</sub><sup>â</sup>, HC<sub>2</sub>O<sub>4</sub><sup>â</sup>/C<sub>2</sub>O<sub>4</sub><sup>2â</sup>, CH<sub>3</sub>COOH/CH<sub>3</sub>COO<sup>â</sup>, and HCO<sub>3</sub><sup>â</sup>/CO<sub>3</sub><sup>2â</sup>) covering a broad pH range (â1 to 10),
as well as an inorganicâorganic mixture (sulfate-oxalate).
Given the ionic strength of the inorganic solutions, the H<sup>+</sup> activity, ÎłÂ(H<sup>+</sup>), yielded lower values (0.68â0.75)
than the organic and mixed systems (0.72â0.80). A consistent
relationship between increasing peak broadness with decreasing pH
was observed for acidic species, but not their conjugate bases. Greater
insight into spectroscopic responses to acidâbase equilibria
for more complicated mixtures is still needed to understand the behavior
of atmospheric aerosols