The Subsurface Biogeochemical Research (SBR) program seeks to advance a robust, predictive understanding of how watersheds function as complex hydrobiogeochemical systems and how these systems respond to perturbations caused by changes to earth system processes, land use and land cover, contaminant loading, and compounding disturbances.
The Department of Energy (DOE) is responsible for advancing the energy, environmental, and nuclear security objectives of the United States. To better address this DOE mission, the Secretary of Energy reorganized DOE in 2013 to bring together its fundamental science and applied research programs, capabilities, and activities within the Undersecretary Office for Science and Energy (US/SE). The nexus of energy and water is one area of common interest and activity for both the science and energy portions of the DOE portfolio. In part, the water-energy nexus seeks to optimize the energy efficiency of water management, treatment, distribution, and end use systems, as well as enhance the reliability and resilience of energy and water systems. Moreover, flows of energy and water are intrinsically interconnected, in large part due to the characteristics and properties of water that make it so useful for producing energy and the energy requirements to treat and distribute water for human use.
As precipitation patterns and the severity of weather events change over time, there will be accompanying changes to the supply and quality of water (including snowmelt) available for energy infrastructure (e.g., hydropower), as well as for natural ecosystems and land use (e.g., agricultural systems and recreation). These changes will present many challenges, but also offer opportunities. Integrated analysis and modeling of the water-energy nexus requires the simulation of many natural processes and their interactions with anthropogenic inputs in the context of local, regional, and national decisionmaking. The connection of water and energy to land use, watershed function and dynamics, and hydrobiogeochemical processes is particularly important.
The SBR program has long supported research that includes developing mechanistic understanding of hydrobiogeochemical processes of inorganic elements and nutrients, as well as the quantification of the stocks and controls on states, fluxes, and residence times of water throughout the terrestrial system, including surface waters, sediments, groundwater, soils, and the vadose zone. To achieve predictive understanding of this complex terrestrial system, the SBR program supports a range of laboratory- and field-based research activities to obtain mechanistic and kinetic understanding to parameterize fully coupled models of the terrestrial ecosystem. These models incorporate metabolic processes of microbes, molecular-scale understanding of geochemical constituents and the stability and speciation; biogeochemical reaction kinetics; process couplings and feedbacks between the various microbial, geochemical, geologic, and ecohydrologic system components; and diagnostic signatures of the system response at varying spatial and temporal scales. Ranging from molecular scales to watersheds, SBR’s modeling efforts incorporate huge spatial scales, but also include fine-scale resolution of critical interfaces to enable correct calculations of nutrient, microbial, elemental, and water fluxes. Multiple timescales ranging from nanosecond molecular reactions to days, months and years for watershed- and basin-scale processes, also are considered and resolved, because the ultimate aim is to enable prediction of not only the structure but also the functioning of a given terrestrial system from days to decades.
Scales of BER and SBR Research. (Left) BER supports research that spans enormous spatial and temporal scales. (Right) The SBR program supports mechanistic hydrobiogeochemistry research to understand the function of watersheds and larger-scale environmental processes. [Right image courtesy Lawrence Berkeley National Laboratory]
The SBR program supports three large field-based Scientific Focus Area (SFA) projects at DOE national laboratories: Pacific Northwest National Laboratory (PNNL), Lawrence Berkeley National Laboratory (LBNL), and Oak Ridge National Laboratory (ORNL). As multi-year investments, these large SFAs are investigating the influence of hydrologic processes on biogeochemical cycling within watersheds and river basins, including the impacts of groundwater-surface water interaction on nutrients such as carbon, nitrogen, phosphorus and sulfur, and the biogeochemical transformations of other elements such as iron and manganese, and contaminants such as uranium, technetium, mercury, chromium, plutonium). Within each SFA, interdisciplinary scientific teams have developed long-term research programs built around established field research sites in eastern and western river basins. The sites include a mountainous headwater catchment in the semi-arid Upper Colorado River Basin (LBNL SFA), a 75 km flood-plain reach of the Columbia River in the sparsely vegetated Columbia Plateau region (PNNL SFA), and the spring-derived East Fork Poplar Creek that flows into the Clinch River in humid Oak Ridge, TN (ORNL SFA). These projects also serve as modeling use cases in the Interoperable Design of Extreme-scale Application Software (IDEAS) project, which is aimed at improving scientific productivity and system-level predictability using extreme-scale scientific computing. With coordination and community participation, these three SFAs offer significant potential for transforming our understanding of the role of interfaces in predicting hydrology-driven biogeochemical cycling and, in particular, advancing understanding of groundwater-surface water interactions across a range of river basin characteristics.
The SBR program also supports three smaller SFA projects that focus on fundamental biogeochemical interactions extending from molecular to core scales, but target critical processes of relevance to larger field scales and leverage unique DOE analytical capabilities at their respective national laboratories. The Argonne National Laboratory (ANL) SFA seeks to characterize coupled biotic-abiotic molecular-scale iron, sulfur, heavy metal, and radionuclide transformations, integrated over different length scales, to provide knowledge necessary for understanding subsurface processes and predicting contaminant reactivity and transport. The SLAC National Accelerator Laboratory (SLAC) SFA seeks to investigate fundamental biogeochemical redox processes that control uranium and biogeochemical critical element behavior, with emphasis on hot spots of microbial and chemical activity in organic-rich fine-grained sediments. The Lawrence Livermore National Laboratory (LLNL) SFA seeks to identify the dominant biogeochemical processes and the underlying mechanisms that control actinide transport (focusing on plutonium and neptunium) in an effort to reliably predict and control the cycling and mobility of actinides in the subsurface.
The SBR program supports mission-oriented research performed by