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Earth Systems Biogeochemistry Laboratory

The ESB laboratory supports the study of the biogeochemical cycles of carbon, nitrogen, and other elements and nutrients in soils, sediments, rocks, and surface- and groundwaters through physical and chemical analyses. 

The U.S. Geological Survey’s Regional Assessment of Drought Impacts on Soils (RADIS) project and the Earth Systems Biogeochemistry (ESB) Laboratory are managed out of the Geosciences and Environmental Change Science Center (GECSC). 

In addition to standard practices, the ESB Laboratory develops new and innovative methods and techniques that allow the USGS to study and map biogeochemical cycles in the arid and semiarid environments of the Southwestern United States.

Regional Assessment of Drought Impacts on Soils (RADIS)

Summary

The goals of this project are to (1) develop and test a spatially explicit framework for quantifying the heterogeneity of soil functions at the regional (i.e., drainage basin) scale and (2) to better forecast the response of soils to changes such as persistent drought. At present, this work focused on characterizing the storage of organic matter (SOM) in soils – a soil function that is essential for ecosystem and soil health, agricultural productivity, and mitigation of climate change. To accomplish this goal, we utilize an approach that integrates soil mapping based on previously available geospatial data, field-based collection and measurement of soil properties and conditions, and laboratory-based experimentation. The end result of this effort will be a data-driven, spatially explicit representation of soil characteristics that can be used to improve resource management and forecasts.

 

Approach

Our approach is shaped by the need to scale-up our understanding of soil processes, which are often developed at the pore and profile scales, to capture landscape scale heterogeneity without losing mechanistic detail. This effort requires the integration of geospatial mapping, detailed experimentation and sample analyses, and mathematical modeling. To accomplish this, we are testing a Soil Functional Unit Mapping approach. By leveraging the soil functional unit maps, we can more efficiently collect and analyses soils in order to better understand the primary processes that drive landscape scale variation in the soil functions of interest. For each functional unit we will: (1) measure properties of SOM including the partitioning of organic carbon into measurable fractions that differ in their mean transit times through the soils, (2) characterize physical, chemical, or biological soil factors that are indicative of local and regional scale variations in SOM dynamics, and (3) design and implement laboratory experiments to further constrain how local scale soil processes vary between the soil units.

 

Pilot Study

The pilot study for this work is based in East River Valley of the Elk Mountains and surrounding areas, located near Gothic, Colorado. The East River drains a mix of alpine, sub-alpine, and montane regions and is home to the Rocky Mountain Biological Laboratory and the Department of Energy Science Focus Area. Working in collaboration with those entities as well as individual collaborators from several institutions including the Department of Energy and the National Ecological Observation Network (NEON), we are leveraging a long history of scientific study in this region to test and refine the soil functional mapping approach.

A down valley view of the East River from the 401 Trail, with Gothic Mountain and Mt. Crested Butte visible in the distance
A down valley view of the East River from the 401 Trail, with Gothic Mountain and Mt. Crested Butte visible in the distance. (Photo: Corey Lawrence)

 

Future Work

Future research goals for the project are to (1) develop model-data fusion approach for coupling of Soil Functional Mapping with local (reactive transport) and regional scale soil models and (2) expand the Soil Functional Mapping approach to other areas of the Upper Colorado River Basin region.                        

 

Capabilities

The primary technical capabilities of the Earth Systems Biogeochemistry (ESB) laboratory include determination of organic carbon, inorganic carbon, residual organic carbon, and total nitrogen contents in solid samples (soils, sediment, vegetation, etc.) and determination of dissolved organic carbon content in liquid samples.

General sample preparation tasks, such as air-drying, sieving, grinding, and splitting, and particle size analysis are conducted in cooperation with the Soils and Sediments laboratory. Specialized sample preparation capabilities in the ESB Laboratory include freeze-drying of liquid and solid samples, soil density fractionation, and soil and root incubations in preparation for radiocarbon analyses.

 

Key Equipment

Novel solid and liquid state elemental analyzers at USGS ESB Lab

The ESB Laboratory houses novel solid and liquid state elemental analyzers (pictured). Additionally, the ESB lab houses standard environmental sample preparation instrumentation including a shaker table, balances and a microbalance, a centrifuge, drying and muffle furnaces, a 2.5-L freeze dryer, a ball mill grinder, an ultra-pure water purification system, a gas chromatograph, and a sonifier.

 

 

 

 

Collaborators

 

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