Advance soil studies with in situ high-precision measurements of greenhouse gases and light stable isotopes.
The fractionation of light stable isotopes of soil components and their ensuing signatures are commonly used to infer past ecologic and climatic shifts in the soil record. They can also support the investigation of a variety of environmental questions.
Rugged Picarro CRDS analyzers allow you to make high-precision, lab-quality isotope and concentration measurements in the field. With those real-time results, you can redirect research on the fly to address the most interesting questions.
Using a Picarro greenhouse gas analyzer, researchers at the Inner Mongolia Agricultural University have gained a deeper understanding of how soils absorb and emit CO2 and CH4. They quantified the flux of those gases in inner Mongolian desert grassland, while also quantifying the greenhouse contribution of livestock discharge. In a separate study, the same group explored the effect of stocking rate on soil-atmosphere methane flux during the freeze-thaw cycles.
Get more from these papers:
- Contribution of Urine and Dung Patches from Grazing Sheep to Methane and Carbon Dioxide Fluxes in an Inner Mongolian Desert Grassland.
- Effect of Stocking Rate on Soil-Atmosphere CH4 Flux during Spring Freeze-Thaw Cycles in a Northern Desert Steppe, China.
Using a Picarro isotopic CO2 analyzer, researchers in Australia and Italy have shown the relative CO2 contribution from roots, soil microbes and the decomposition of soil organic matter.
Get more from these papers:
- Dual-Chamber Measurements of δ13C of Soil-Respired CO2 Partitioned Using a Field-Based Three End-Member Model.
- Challenges in measuring the δ13C of the soil surface CO2 efflux.
- High-resolution δ13CO2 soil efflux monitoring in tree girdling experiment exposes large temporal variability.
Nitrogen isotopes of N2O gas can reveal the relative rates of microbial nitrification and denitrification processes in soil. Picarro’s portfolio of instruments now includes two powerful new tools for nitrogen cycle studies; isotopic N2O analyses and [N2O] + [CH4] analyses.
Researchers at Dalhousie University, in collaboration with Picarro, have used the iN2O CRDS system to determine the isotopic distribution of nitrous oxide generated from selected inorganic reactions. The data illuminated the connections between molecular dynamics underlying the formation mechanism and related isotopic signatures of N2O, as required for interpretation of observed signatures in field measurements.
Researchers are also using Picarro analyzers to study soil incubation and metabolism. By monitoring isotopic carbon, they were able to identify variations in CO2 production under varying moisture, temperature and substrate conditions. Paul Dijkstraa and colleagues at Northern Arizona University used position-specific tracer labeling techniques and modeling to analyze the response of soil metabolism to various stressors.
Get more from these papers:
- Modeling soil metabolic processes using isotopologue pairs of position-specific 13C-labeled glucose and pyruvate.
- Effect of temperature on metabolic activity of intact microbial communities: Evidence for altered metabolic pathway activity but not for increased maintenance respiration and reduced carbon use efficiency.
- Probing carbon flux patterns through soil microbial metabolic networks using parallel position-specific tracer labeling.
The flux of CO2 and CH4 from large areas can be quantified with eddy covariance techniques which require fast measurement of those species. Our 10 Hz, fast measuring GHG analyzer enables this, as when Prof. Wade McGillis of Columbia University used Picarro flux instrumentation on the largest green rooftop in Manhattan, NY.
Get more from the paper: Picarro’s New Flux Instrument Captures CO2, CH4 & H2O Fluxes by Measuring Concentrations at 10 Hz with the Best Precision and Lowest Drift.
Soil organic matter
After Dumas combustion, researchers at the University of Copenhagen quantitatively converted carbon content of bulk soil samples into CO2 for isotopic carbon analysis with a Picarro CRDS analyzer. They used the CM-CRDS to measure 13C in rock samples.
The composition of gas within soil can be studied using a variety of Picarro analyzers. Natural soils contain CO2, CH4, and N2O. Soil gas near landfills and sequestration sites can help determine the level of greenhouse gas emissions from landfills, including fugitive losses during pipeline transport from these facilities.
The flow of groundwater through the soil can be studied with stable isotopes. Many researchers are using Picarro water isotope analyzers to study pore water source links and process information using the natural variation in 18O and D. In fact, Wassenaar, et al., have measured pore water from equilibrated headspace water vapor of environmental and geologic cores using a Picarro isotopic H2O analyzer.
McDonnell, et al., have conducted studies using bromide tracers and isotopic water measurements to track water flow for particular sites.
Get more from the paper: Macropore flow of old water revisited: where does the mixing occur at the hillslope scale?
Soil moisture can also be evaporated from a soil sample for immediate isotopic analysis using Picarro’s Induction Module-CRDS system. The IM uses inductive heating to drive off soil moisture into a dry gas stream that feeds into a Picarro water isotope analyzer for 18O and D analysis.