BER launches Environmental System Science Program. Visit our new website under construction!

U.S. Department of Energy Office of Biological and Environmental Research

BER Research Highlights


How Shoreline Vegetation Protects Sediment-Bound Carbon
Published: December 20, 2017
Posted: March 07, 2018

A new study investigates the mechanisms and pace of carbon processing at the terrestrial-aquatic interface of a major river corridor.

The Science
Soils and nearshore sediments comprise a reservoir of carbon (C) 3.2 times larger than all the carbon stored in the atmosphere. Terrestrial carbon (e.g., from falling leaves and roots growing underground) is increasingly transported into aquatic systems due to significant changes in how land is used as the population increases, but little is known about the processing of carbon along terrestrial-to-aquatic continuums.

A new study led by ecologists Emily Graham and James Stegen at the Pacific Northwest National Laboratory takes a closer look at how carbon inputs along the terrestrial-aquatic interface change the mechanisms and pace of carbon processing. Their research also sheds light on how some of the carbon along shorelines remains in place for millennia.

The Impact
This research provides ultrahigh-resolution data to infer new mechanisms of carbon oxidization along a terrestrial-aquatic boundary. The work will help protect watersheds by providing the underpinnings for a new conceptualization of biogeochemical function within models used to predict how river corridors function.

Summary
A bird’s eye view of the Columbia River in southeastern Washington State reveals varied ecological conditions ranging from dense vegetation to dry, rocky shoreline, and this variability leads to disparities in carbon inputs. In this study, researchers compared the amount of carbon contained within sediments, the rate of metabolism, and the metabolic pathways associated with carbon loss in each type of terrain.

Contrary to the prevailing "priming" paradigm of carbon loss in soils, the data indicate that vegetation “protects” the bound carbon already in nearshore sediments. Researchers learned that water-soluble and thermodynamically favorable organic carbon (OC) protects bound OC from oxidation in densely vegetated areas—presumably because it is easier to break down than the bound OC. Areas with sparse vegetation were more likely to metabolize bound OC, likely leading to the loss of carbon from longer-term stored carbon pools. A unifying principle in both environments, however, seems to be the use of thermodynamically favorable carbon as a preferred substrate pool, providing a starting point for modelling the influences of carbon character in heterogeneous landscapes.

“Another interesting data point is that contrasting metabolic pathways oxidize OC in the presence versus absence of vegetation,” said Graham. “Put simply, we have two different environments with distinct C inputs, C pools, and microbial communities. Each microbial community adapts to the resources available in their local environment and processes the C that returns the most energy back to them.”

These important discoveries are just the tip of the iceberg, Graham and Stegen say. More studies are needed to understand and model the patterns of carbon loss in changing land conditions.

Contacts
BER Program Managers
David Lesmes
Paul Bayer
Paul.Bayer@science.doe.gov, 301-903-5324

Principal Investigators
Emily Graham
Pacific Northwest National Laboratory
emily.graham@pnnl.gov

James Stegen
Pacific Northwest National Laboratory
James.stegen@pnnl.gov

Funding
This research was supported by the Subsurface Biogeochemical Research (SBR) program of the Office of Biological and Environmental Research (BER), within the U.S. Department of Energy (DOE) Office of Science, as part of SBR's Scientific Focus Area (SFA) at the Pacific Northwest National Laboratory (PNNL). This research was performed using Institutional Computing at PNNL

Publications
Graham, E., et al. “Carbon inputs from riparian vegetation limit oxidation of physically bound organic carbon via biochemical and thermodynamic processes.” Journal of Geophysical Research: Biogeosciences 122(12), 3188–3205 (2017). [DOI:10.1101/105486].

Related Links
PNNL SFA Highlight Slide
https://phys.org/news/2016-12-microbial-hyporheic-zone.html
http://sbrsfa.pnnl.gov/docs/highlights/Highlight_Stegen_Microbial_Communities_11282016.pdf
http://sbrsfa.pnnl.gov/docs/highlights/Highlight_Stegen_10-8-2015.pdf
http://sbrsfa.pnnl.gov/docs/highlights/Highlight_Stegen_et_al_2015.pdf

Topic Areas:

  • Research Area: Carbon Cycle, Nutrient Cycling

Division: SC-33.1 Earth and Environmental Sciences Division, BER

 

BER supports basic research and scientific user facilities to advance DOE missions in energy and environment. More about BER

Recent Highlights

Jan 11, 2022
No Honor Among Copper Thieves
Findings provide a novel means to manipulate methanotrophs for a variety of environmental and in [more...]

Dec 06, 2021
New Genome Editing Tools Can Edit Within Microbial Communities
Two new technologies allow scientists to edit specific species and genes within complex laborato [more...]

Oct 27, 2021
Fungal Recyclers: Fungi Reuse Fire-Altered Organic Matter
Degrading pyrogenic (fire-affected) organic matter is an important ecosystem function of fungi i [more...]

Oct 19, 2021
Microbes Offer a Glimpse into the Future of Climate Change
Scientists identify key features in microbes that predict how warming affects carbon dioxide emi [more...]

Aug 25, 2021
Assessing the Production Cost and Carbon Footprint of a Promising Aviation Biofuel
Biomass-derived DMCO has the potential to serve as a low-carbon, high-performance jet fuel blend [more...]

List all highlights (possible long download time)