The Subsurface Biogeochemical Research (SBR) program seeks to advance a robust, predictive understanding of how watersheds function as integrated hydrobiogeochemical systems and how these systems respond to perturbations caused by changes in weather patterns, extremes, land use, water management, vegetation cover, snowmelt timing, and nutrient and contaminant release.
SBR Watershed Testbeds. SBR supports a network of watershed testbeds within the contiguous United States where national laboratory, university, and interagency partners work in interdisciplinary teams to address SBR's priority research objectives and advance watershed system science for energy. [Image courtesy LBNL]
Significant fundamental knowledge gaps impede current watershed models from predicting system dynamics and evolution with the confidence required to address pressing energy and environmental challenges. To address these gaps, SBR has five research priority objectives that are being pursued through a network of watershed testbeds within the contiguous United States. They require the systems-level approaches and perspectives that are hallmarks of SBR research and include:
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 LBNL]
To address its priority research objectives, 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, and 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 floodplain reach of the Columbia River in the sparsely vegetated Columbia Plateau region near Richland, Washington (PNNL SFA), and the spring-derived East Fork Poplar Creek that flows into the Clinch River in humid Oak Ridge, Tennessee (ORNL SFA).
In particular, the LBNL SFA is developing new insights and scale-aware approaches to predict how mountainous watersheds retain and release water, nutrients, carbon, and metals and respond to perturbations over episodic through decadal timescales. The PNNL SFA is quantifying and predicting hydrobiogeochemical and ecological impacts of hydrologic exchange between subsurface and river environments, especially in hydropower-impacted, highly managed systems. The ORNL SFA is determining the fundamental mechanisms and environmental factors that control mercury biogeochemical transformations at key interfaces in terrestrial and aquatic ecosystems.
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 current 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 they 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 is elucidating the molecular- to meter-scale interplay among microbial processes, solution chemistry, and mineralogy contributing to the mobility of elements and contaminants in hydrologically dynamic systems. The SLAC National Accelerator Laboratory (SLAC) SFA is quantifying and modeling mechanisms by which fine-scale biogeochemical and transport processes in shallow alluvial aquifers couple to one another and control water quality under hydrologically variable conditions. The Lawrence Livermore National Laboratory (LLNL) SFA is advancing the understanding of subsurface actinide behavior from the molecular to field scale to provide a scientific basis for remediation and long-term stewardship of groundwater quality at DOE legacy sites.
The SBR program supports mission-oriented research performed by