Abstract:

Marsh soil nitrification rates were determined approximately bi-monthly at the Louisiana Universities Marine Consortium (LUMCON) saltmarsh mesocosm facility in Cocodrie, Louisiana. These twelve hydrologically-isolated, large (~3m diameter) mesocosms were planted with intact Spartina alterniflora and soil sections in January 2018. In July, September, and November 2018 and January, March, May, and June 2019, 5 out of 25 possible central grids were randomly selected to be sampled within each marsh mesocosm. A 0.25m x 0.25 m quadrat was randomly placed within each grid and a 2.6cm diameter core was taken from each plot and all 5 cores were pooled into a single whirlpak bag to generate a homogenized sample capturing the spatial heterogeneity across each mesocosm. The soils were then incubated to determine nitrification potential rates following the methods described in Marton et al. (2015) and Schutte et al. (2020). This dataset represents results prior to the addition of oil to some of the mesocosms as part of large-scale oiling experiment initiated on 2019-07-08.

Suggested Citation:

Roberts, B.J.. 2020. Soil nitrification potential rates in marsh mesoscosms prior to oiling: July 2018-June 2019. Distributed by: GRIIDC, Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/n7-f7x0-e478

Purpose:

This work provides baseline data on nitrification potential rates in all 12 marsh mesocosms prior to the initiation of mesocosm oiling experiment that began on 2019-07-08. This baseline information can also be used to compare temporal nitrification dynamics in the marsh mesocosms with other nearby marsh sites.

Data Parameters and Units:

Year: year of sampling; Month-name: month of sampling (3 letter month abbreviation); Month-number: month of sampling (1= Jan, 2 = Feb, etc.); Date: date that sampling took place (MM/DD/YYYY); Mesocosm number: ID number assigned to marsh mesocosm that was sampled (1-12); Sampling grid: region of mesocosm sampled (1-25), with mesocosm being divided into 25 total grids (5 x 5); Oil treatment: Oiling level later applied to mesocosm on 2019-07-08 (NOTE: all sampling in this dataset occurred prior to oiling); Nitrification potential rate (nmol NO3-N/gdw /d): rate of denitrification potential determined from a homogenized surface soil sample collected from each mesocosm.

Methods:

The sampling methods employed in this dataset are based on those detailed in Martin et al. (2015) and Schutte et al. (2020). Briefly, five out of 25 central grids were randomly selected to sample within each of 12, 3m diameter marsh mesocosms during each bi-monthly sampling period between July 2018 and June 2019. A 0.25m x 0.25m quadrat was randomly placed within each grid and then a 2.6cm diameter core was taken from each plot and all 5 cores were pooled into a single whirpak bag to generate a homogenized sample capturing the spatial heterogeneity across each mesocosm. The soils were then incubated to determine nitrification potential rates following the methods described in Marton et al. (2015) and Schutte et al. (2020). All sampling took place prior to the addition of oil to some of the mesocosms as part of large-scale oiling experiment initiated on 2019-07-08.

Provenance and Historical References:

Marton JM, Roberts BJ, Bernhard AE, Giblin AE. 2015. Spatial and temporal variability of nitrification potential and ammonia-oxidizer abundances in Louisiana salt marshes. Estuaries and Coasts 38(6):1824-1837. DOI: 10.1007/s12237-015-9943-5. Schutte CA, Marton JM, Bernhard AE, Giblin AE, Roberts BJ. 2020. No evidence for long-term impacts of oil spill contamination on salt marsh soil nitrogen cycling processes. Estuaries and Coasts DOI: 10.1007/s12237-020-00699-z.

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