Delay in external lab particulate carbon and nitrogen data
February 7, 2022
In August 2020, NEON discovered that some Particulate Organic Matter (POM) isotope data may have been impacted by the presence of inorganic carbon. NEON and the contracted external lab have worked together to develop a method to remove inorganic carbon from samples via acidification. Routine sample analysis for POM isotopes has been paused. The pilot study to determine which sites require acidification will be completed by April 30, 2022.
In addition, to reduce redundancy in lab analyses, NEON is transitioning total particulate carbon and total particulate nitrogen analysis for the Chemical properties of surface water (DP1.20093.001) data product to the lab that reports POM stable isotope ratios. The lab contract updates for this shift will take place alongside the updates for POM acidification. While the contract is being updated, NEON staff have been manually uploading older POM data (through October 2020) to the Chemical properties of surface water (DP1.20093.001) data product to reduce the delay impact of the pilot study.
After the acidification results are finalized and the external lab contract is updated, shipping and analysis will proceed for all affected data products. Users should expect data publication to be up-to-date by September 30, 2022.
This delay affects the following data products, with published analyte – analyteUnits in parentheses:
Periphyton, seston, and phytoplankton chemical properties (DP1.20162.001) and Stable isotopes in surface water (DP1.20206.001):
Particulate organic C stable isotope ratio (d13C – perMill)
Particulate organic C concentration (carbon – migrogramsPerLiter)
Particulate organic N stable isotope ratio (d15N – perMill)
Particulate organic N concentration (nitrogen – microgramsPerLiter)
Chemical properties of surface water (DP1.20093.001):
Total particulate C (TPC – microgramsPerLiter)
Total particulate N (TPN – microgramsPerLiter)
In addition to isotope ratios and concentrations of carbon and nitrogen, the external lab will provide method summary data for Chemical properties of surface water (DP1.20093.001) in the swc_externalLabSummaryData table. Method summary data is already available for Periphyton, seston, and phytoplankton chemical properties (DP1.20162.001) and Stable isotopes in surface water (DP1.20206.001) as part of the existing contract. Exact MDL values will be reported once data upload begins. Until that data is published, users should expect MDL values for particulate C and N masses to be within the following ranges:
C: 4 µg
N: 6 µg
Note: To compare external lab data to MDL values, users will need to multiply TPC and TPN concentrations by the field “sampleVolumeFiltered” found in the swc_fieldData table.
We will provide an update by the end of April 2022 confirming the progress of the timeline outlined above. Please use the Contact Form for further inquiries; please select DP1.20162.001 (for algal chemistry), DP1.20206.001 (for surface water isotopes) or DP1.20093.001 (for surface water chemistry) in the Data Product drop-down list and include the term "INC0039921" in the body of your request.
