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

BER Research Highlights


First Measurements of Dark Reactive Oxygen Species in a Groundwater Aquifer
Published: June 14, 2017
Posted: April 18, 2018

First measurement of the presence of hydrogen peroxide concentrations in groundwater establishes importance of reactive oxygen species in the subsurface.

The Science 
Reactive oxygen species (ROS) such as hydrogen peroxide (H2O2) are very short-lived intermediate molecules generated during the one-electron reduction of oxygen to water through photochemical oxidation or through a “dark” process involving microorganisms. To date, ROS have been found in the deep ocean, sediments, and fresh waters. Now, a team of scientists has demonstrated a dark biological process that generates hydrogen peroxide in groundwater from an alluvial aquifer.

The Impact
Hydrogen peroxide and an associated class of compounds called Reactive Oxygen Species (ROS) have long been known to be important drivers of biogeochemical cycling and contaminant decomposition in surface water (oceans, rivers, and lakes). By demonstrating that hydrogen peroxide and therefore the associated group of reactive oxygen species were widely distributed in the groundwater of a uranium-contaminated alluvial floodplain, scientists have established that ROS likely are important to the chemistry and functioning of biogeochemical cycles in this floodplain and other groundwater systems. The presence of ROS in some groundwater systems may help explain the apparent non-equilibrium conditions in these systems, as well as potential organic matter oxidation pathways.

Summary
The commonly held assumption that photodependent processes dominate H2O2 production in natural waters has recently been questioned. This paper demonstrated for the unrecognized and light-independent generation of H2O2 in groundwater of an alluvial aquifer adjacent to the Colorado River near Rifle, CO.

Using a sensitive chemiluminescent method to detect H2O2 along vertical profiles at various locations across an alluvial aquifer of the Colorado River, a team of scientists from Lawrence Berkeley National Laboratory (LBNL), Peking University, and the University of New South Wales, found that H2O2 concentrations ranged from lower than the detection limit (<1 nM) to 54 nM. The data also suggest dark formation of H2O2 is more likely to occur in transitional redox environments where reduced elements (e.g., reduced metals and NOM) meet oxygen, such as oxic-anoxic interfaces. A simplified kinetic model involving interactions among iron, reduced NOM, and oxygen was able to reproduce roughly many, but not all, of the features in the detected H2O2 profiles. This suggests there likely are other minor biological and/or chemical controls on H2O2 steady-state concentrations in such aquifer. Because of its transient nature, the widespread presence of H2O2 in groundwater indicates the existence of a balance between H2O2 sources and sinks, which potentially involves a cascade of various biogeochemically important processes that could have significant impacts on metal/nutrient cycling in groundwater-dependent ecosystems, such as wetlands and springs. More importantly, these results demonstrate that ROS are not only widespread in oceanic and atmospheric systems, but are also present in the subsurface domain, possibly the least understood component of the Earth system, and yet, critical for understanding a wide variety of biogeochemical cycles.

Contacts (BER PM)
David Lesmes
Subsurface Biogeochemical Research
David.Lesmes@science.doe.gov

(PI Contact)
Peter S. Nico
Berkeley Lab
psnico@lbl.gov

Funding
DOE-SBR Watershed Function SFA

Publications
Yuan, X., P. S. Nico, X. Huang, T. Liu, C. Ulrich, K. H. Williams, and J. A. Davis. “Production of hydrogen peroxide in groundwater at Rifle, Colorado.” Environ. Sci. Technol. 51, 7881-7891 (2017). [DOI:10.1021/acs.est.6b04803]

Topic Areas:

  • Research Area: Subsurface Biogeochemical Research

Division: SC-23.1 Climate 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

May 10, 2019
Quantifying Decision Uncertainty in Water Management via a Coupled Agent-Based Model
Considering risk perception can improve the representation of human decision-making processes in age [more...]

May 09, 2019
Projecting Global Urban Area Growth Through 2100 Based on Historical Time Series Data and Future Scenarios
Study provides country-specific urban area growth models and the first dataset on country-level urba [more...]

May 05, 2019
Calibrating Building Energy Demand Models to Refine Long-Term Energy Planning
A new, flexible calibration approach improved model accuracy in capturing year-to-year changes in bu [more...]

May 03, 2019
Calibration and Uncertainty Analysis of Demeter for Better Downscaling of Global Land Use and Land Cover Projections
Researchers improved the Demeter model’s performance by calibrating key parameters and establi [more...]

Apr 22, 2019
Representation of U.S. Warm Temperature Extremes in Global Climate Model Ensembles
Representation of warm temperature events varies considerably among global climate models, which has [more...]

List all highlights (possible long download time)