Skip to main content
OSTI.GOVU.S. Department of Energy Office of Scientific and Technical Information
U.S. Department of Energy
Office of Scientific and Technical Information
 

Deep Unsaturated Zone Contributions to Carbon Cycling in Semiarid Environments

Journal Article · · Journal of Geophysical Research. Biogeosciences
DOI:https://doi.org/10.1029/2018JG004669· OSTI ID:1479368
 [1];  [1];  [1];  [1];  [1];  [1];  [1];  [1];  [1]
  1. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Earth and Environment Sciences Area
+ Show Author Affiliations

Understanding terrestrial carbon cycling has relied primarily on studies of topsoils that are typically characterized to depths shallower than 0.5 m. At a semiarid site instrumented down to 7 m, here we measured seasonal- and depth-resolved carbon inventories and fluxes and groundwater and unsaturated zone flow rates. Measurements showed that ~30% of the CO2 efflux to the atmosphere (60% in winter) originates from below 1 m, contrary to predictions of less than 1% by Earth System Model land modules. Respiration from deeper roots and deeper microbial communities is supported by favorable subsurface temperatures, moisture, and oxygen availability. Below 1 m, dissolved organic carbon fluxes from the overlying soil and C from deep roots and exudates are expected to be important in sustaining microbial respiration. Finally, because these conditions are characteristic of semiarid climate regions, we contend that Earth System Model land modules should incorporate such deeper soil processes to improve CO2 flux predictions.

Research Organization:
Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
Sponsoring Organization:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
Grant/Contract Number:
AC02-05CH11231
OSTI ID:
1479368
Alternate ID(s):
OSTI ID: 1472185
Journal Information:
Journal of Geophysical Research. Biogeosciences, Journal Name: Journal of Geophysical Research. Biogeosciences Journal Issue: 9 Vol. 123; ISSN 2169-8953
Publisher:
American Geophysical UnionCopyright Statement
Country of Publication:
United States
Language:
English

References (41)

Representing leaf and root physiological traits in CLM improves global carbon and nitrogen cycling predictions: LEAF AND ROOT TRAITS IN CLM journal May 2016
Root traits explain observed tundra vegetation nitrogen uptake patterns: Implications for trait-based land models: Tundra N Uptake Model-Data Comparison journal December 2016
A global analysis of root distributions for terrestrial biomes journal November 1996
The effect of oxygen concentration on the decomposition of organic materials in soil journal July 1961
Deep Autotrophic Soil Respiration in Shrubland and Woodland Ecosystems in Central New Mexico journal October 2011
A comparative study of dissolved organic carbon transport and stabilization in California forest and grassland soils journal July 2008
A comparative study of dissolved organic carbon transport and stabilization in California forest and grassland soils journal September 2008
Influence of hydrological, biogeochemical and temperature transients on subsurface carbon fluxes in a flood plain environment journal February 2016
Deep soil organic matter—a key but poorly understood component of terrestrial C cycle journal May 2010
A review of the molecular diffusivities of H2O, CO2, CH4, CO, O3, SO2, NH3, N2O, NO, and NO2 in air, O2 and N2 near STP journal March 1998
Using the gradient method to determine soil gas flux: A review journal July 2014
Geochemical, mineralogical and microbiological characteristics of sediment from a naturally reduced zone in a uranium-contaminated aquifer journal August 2012
Variably saturated flow and multicomponent biogeochemical reactive transport modeling of a uranium bioremediation field experiment journal November 2011
Transport and humification of dissolved organic matter within a semi-arid floodplain journal July 2017
Profile storage of organic/inorganic carbon in soil: From forest to desert journal March 2010
Using strontium isotopes to evaluate the spatial variation of groundwater recharge journal October 2018
Priming effects: Interactions between living and dead organic matter journal September 2010
Cycling downwards – dissolved organic matter in soils journal September 2012
CO 2 dynamics in the Amargosa Desert: Fluxes and isotopic speciation in a deep unsaturated zone : CO journal February 2005
Estimation of dissolved organic carbon contribution from hillslope soils to a headwater stream: DISSOLVED ORGANIC CARBON FROM SOILS TO STREAM journal September 2012
In situ measurement of microbial activity and controls on microbial CO 2 production in the unsaturated zone journal March 1993
Improved modelling of soil nitrogen losses journal July 2015
Erratum: Biophysical controls on organic carbon fluxes in fluvial networks journal July 2009
Acetate Availability and its Influence on Sustainable Bioremediation of Uranium-Contaminated Groundwater journal June 2011
Total carbon and nitrogen in the soils of the world journal January 2014
Evaluating litter decomposition in earth system models with long-term litterbag experiments: an example using the Community Land Model version 4 (CLM4) journal October 2012
Total carbon and nitrogen in the soils of the world journal June 1996
Evaluation of 11 terrestrial carbon-nitrogen cycle models against observations from two temperate Free-Air CO 2 Enrichment studies journal January 2014
The dominant role of semi-arid ecosystems in the trend and variability of the land CO2 sink journal May 2015
Sequestration of inorganic carbon in soil and groundwater journal May 2015
Uncertainties in CMIP5 Climate Projections due to Carbon Cycle Feedbacks journal January 2014
Simulation of Global Land Surface Conditions from 1948 to 2004. Part I: Forcing Data and Evaluations journal October 2006
The Vertical Distribution of soil Organic Carbon and its Relation to Climate and Vegetation journal April 2000
Microbial Processes in the Vadose Zone journal February 2005
Predicting the Gas Diffusion Coefficient in Repacked Soil journal January 2000
Microbial Processes in the Vadose Zone journal January 2005
Deep Vadose Zone Respiration Contributions to Carbon Dioxide Fluxes from a Semiarid Floodplain journal January 2016
Global soil carbon: understanding and managing the largest terrestrial carbon pool journal February 2014
Causes of variation in soil carbon simulations from CMIP5 Earth system models and comparison with observations journal January 2013
The effect of vertically resolved soil biogeochemistry and alternate soil C and N models on C dynamics of CLM4 journal January 2013
CLM4-BeTR, a generic biogeochemical transport and reaction module for CLM4: model development, evaluation, and application journal January 2013

Cited By (2)

Microbial communities across a hillslope‐riparian transect shaped by proximity to the stream, groundwater table, and weathered bedrock journal May 2019
Depth‐ and Time‐Resolved Distributions of Snowmelt‐Driven Hillslope Subsurface Flow and Transport and Their Contributions to Surface Waters journal November 2019

Similar Records

Deep Vadose Zone Respiration Contributions to Carbon Dioxide Fluxes from a Semiarid Floodplain
Journal Article · Thu Jul 28 00:00:00 EDT 2016 · Vadose Zone Journal · OSTI ID:1582103
Deep Vadose Zone Respiration Contributions to Carbon Dioxide Fluxes from a Semiarid Floodplain
Journal Article · Thu Jul 28 00:00:00 EDT 2016 · Vadose Zone Journal · OSTI ID:1466696

Related Subjects

54 ENVIRONMENTAL SCIENCES
DOC flux
ESM land modules
carbon cycling
carbon fluxes
deep unsaturated zone
semiarid environments