[Ccb_faculty] Fwd: [Envisci-all] ENSC Seminar on Wed, Mar 30 @3:00 PM

[Peter Homyak]

Hi all,

Just forwarding this seminar

-Pete


Peter M. Homyak, Ph.D. (he/him)

Assistant Professor of

Ecosystem and Soil Microbial Processes

Associate Editor: Elementa <https://www.elementascience.org/>

Dept. of Environmental Sciences

University of California, Riverside

900 University Ave

Riverside, CA 92521

Phomyak at ucr.edu

(951) 827-2358 | 312 Sci Lab I

http://petehomyak.weebly.com




---------- Forwarded message ---------
From: Daniel Hirmas <daniel.hirmas at ucr.edu>
Date: Fri, Mar 25, 2022 at 10:04 PM
Subject: [Envisci-all] ENSC Seminar on Wed, Mar 30 @3:00 PM
To: envisci-all at lists.ucr.edu <envisci-all at lists.ucr.edu>


*Speaker:* Dr. Scott D. Wankel, Woods Hole Oceanographic Institution,
Marine Chemistry and Geochemistry Department
*Time/Location:* Wednesday, March 30, 2022 @3:00 PM - 3:50 PM, MSE 103

You're invited!

*Title:* Intricate coupling of carbon, nitrogen and iron redox cycling
underlying the biogeochemical dynamics of N2O

*Abstract:* Over century long timescales, the climatic forcing of nitrous
oxide (N2O) dwarfs that of carbon dioxide. Although increasing atmospheric
levels are linked to excess nitrogen loading and consequent formation via
microbially mediated pathways, factors regulating the emission of N2O to
the atmosphere remain difficult to predict and the global N2O budget
remains poorly constrained. In large part, these challenges stem from the
fact that a diverse number of N2O production pathways may be at work,
especially in environments hosting dynamic redox conditions - and thus
disentangling their relative roles in regulating N2O is challenging. As
coastal ecosystems are especially subject to elevated nitrogen loading, we
have been focusing investigations on better understanding the controls on N2O
production mechanisms in intertidal sediments using a variety of novel
isotopic approaches. Surprisingly, initial findings have indicated that
under elevated nitrate loading, increased emissions of N2O are not mediated
by direct bacterial activity, but instead appear to be largely catalyzed by
fungal denitrification and/or abiotic reaction with reduced iron
(chemodenitrification).
    Expanding on these findings, results from lab experiments focused on
non-traditional production pathways demonstrate high potential for cryptic
cycling processes under dynamic redox oscillations and shed some new light
on factors controlling kinetics, yields, and isotopic composition of
product N2O. As both fungal and chemodenitrification typically exhibit N2O
yields far greater than bacterial production, even small levels of their
activity could produce disproportionately large amounts of N2O, suggesting
the possibility of their potentially substantial, yet widely overlooked,
role especially in coastal ecosystem N2O fluxes. Finally, these findings
may help to explain the notoriously high variability of environmental N2O
fluxes, which may in part be driven by spatial and temporal heterogeneity
in organic matter respiration by fungi and the redox cycling of iron.

[flyer attached]

View upcoming seminars: https://envisci.ucr.edu/news-seminars


Daniel Hirmas
*Associate Professor of Pedology and Graduate Advisor for Continuing
Students*
Department of Environmental Sciences
University of California - Riverside
A: 2228A Geology Building
  Riverside, CA 92521-0424
P: (951) 827-2019
E: daniel.hirmas at ucr.edu
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