Title: Greenhouse Gas Production and Transport in Desert Soils of the Southwestern United States

Abstract

Deserts comprise a large portion of the Earth's land area, yet their role in the fluxes and cycles of greenhouse gases is poorly known and their likely response to climate change largely unexplored. We report a reconnaissance investigation of the concentrations and fluxes of CO₂, CH₄, and N₂O along two elevation (climate) gradients in the southwestern United States. In-soil concentrations of CO₂ increased with elevation (up to 5,000 ppm). Concentrations of CH₄ declined with depth in all soils (to less than 1 ppm), but the rates of decrease with depth increased with elevation. In contrast, concentrations and depth trends of N₂O varied erratically. Soils were net CO₂ sources (0 to >1,500 kg CO₂·ha^-1·year^-1), and net CH₄ sinks (0.2 to >3 kg CH_4·ha^-1·year^-1). The small and variable N₂O fluxes were inconsistent with the trends in soil N δ¹⁵N values, which decreased by 5‰ to 6‰ over about 1,000 m of elevation. The high soil N δ¹⁵N values (up to nearly 17‰ at the lowest elevation) indicate that there is a soil N loss mechanism that is highly depleted in ¹⁵N, and gaseous losses—either NH₃ or N₂O/N₂—are suspected of driving these values. In summary, there appears to be a strong climate control on both soil CO₂ and CH₄ concentrationsmore » and to a lesser degree on calculated fluxes. The soil N trace gas concentrations indicate that deserts can be either small sources or sinks of N₂O and that there may be significant consumption of arid soil N₂O.« less

Authors:

Oerter, Erik  ^[1];

• Search DOE PAGES for author "Oerter, Erik"
• Search DOE PAGES for ORCID "0000-0001-8816-1754"

Mills, Jennifer V.  ^[2];

• Search DOE PAGES for author "Mills, Jennifer V."
• Search DOE PAGES for ORCID "0000-0003-1775-5509"

Maurer, Gregory E. ^[2]; Lammers, Laura Nielsen ^[2]; Amundson, Ronald  ^[2]

• Search DOE PAGES for author "Amundson, Ronald"
• Search DOE PAGES for ORCID "0000-0003-1510-7313"

---

+ Show Author Affiliations

1. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
2. Univ. of California, Berkeley, CA (United States). Dept. of Environmental Science, Policy and Management

Publication Date:

Fri Nov 09 00:00:00 EST 2018

Research Org.:

Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States); University of California, Berkeley, CA (United States); Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)

Sponsoring Org.:

USDOE; California Energy Commission (United States); National Science Foundation (NSF)

OSTI Identifier:

1502002

Alternate Identifier(s):

OSTI ID: 1483350; OSTI ID: 1581316

Report Number(s):

LLNL-JRNL-741058
Journal ID: ISSN 0886-6236; 895365

Grant/Contract Number:  

AC52-07NA27344; AC02-05CH11231

Resource Type:

Accepted Manuscript

Journal Name:

Global Biogeochemical Cycles

Additional Journal Information:

Journal Volume: 32; Journal Issue: 11; Journal ID: ISSN 0886-6236

Publisher:

American Geophysical Union (AGU)

Country of Publication:

United States

Language:

English

Subject:

54 ENVIRONMENTAL SCIENCES; carbon dioxide; methane; nitrous oxide; soil; deserts