Abstract:

Denitrification and nitrogen cycling processes were measured from marsh sediments to determine the impact of oiling on salt marsh ecosystems. Five replicate sediment cores were collected from vegetated marsh and intertidal habitat and incubated for a 24 hour period to examine denitrification and nutrient fluxes using the isotope pairing technique. Data were collected three times in both summer and fall of 2015.

Suggested Citation:

Mortazavi, Behzad. 2017. Nitrogen cycling processes in oil impacted salt marshes on Chandeleur Islands, July, 2015 through February, 2016. Distributed by: GRIIDC, Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/N7MK69XZ

Publications:

Hinshaw, S. E., Tatariw, C., Flournoy, N., Kleinhuizen, A., Taylor, C., Sobecky, P. A., & Mortazavi, B. (2017). Vegetation Loss Decreases Salt Marsh Denitrification Capacity: Implications for Marsh Erosion. Environmental Science & Technology, 51(15), 8245–8253. doi:10.1021/acs.est.7b00618

Purpose:

The purpose of this study was to investigate the denitrification rates in marsh and subtidal habitats that were previous exposed to moderately oiled sediments.

Data Parameters and Units:

Date: month, day and year, Location: Location of site on Chandeleur Island map, Habitat: sediments were collected from intertidal habitats or marsh habitats, Replicate: sample number, Potential Nitrification: potential nitrification rate measured in micromoles of nitrogen per meter squared per hour (µmol N m2 hr-1), Core number: represents the five replicate cores that were collected from each site, Temperature: measured in Celsius (C), Salinity: measured in psu, Denitrification rates: measured in micromoles of nitrogen per meter squared per hour (µmol N m-2 hr-1), NO2+NO3 Flux (nitrite plus nitrate flux): measured in micromoles of nitrogen per meter squared per hour (µmol N m2 hr-1), PO4 Flux (phosphate flux): measured in micromoles of phosphate per meter squared per hour (µmol P m2 hr-1), NO2 Flux (nitrite flux): measured in micromoles of nitrogen per meter squared per hour (µmol N m2 hr-1), NH4 Flux (ammonium flux): measured in micromoles of ammonium per meter squared per hour (µmol N m2 hr-1), NO3 Flux (nitrate flux): measured in micromoles of nitrogen per meter squared per hour (µmol N m2 hr-1), DIN Flux (dissolved inorganic nitrogen flux): measured in micromoles of nitrogen per meter squared per hour (µmol N m2 hr-1), Latitude Degrees: measured in degrees, Latitude Minutes: measured in minutes, Latitude Seconds: measured in seconds, Longitude Degrees: measured in degrees, Longitude Minutes: measured in minutes, Longitude Seconds: measured in seconds.

Methods:

The denitrification rates were measured using the isotope pairing technique. Five replicate cores (9.5 cm ID, 24 cm height) from subtidal and marsh habitats were collected to a depth of 20 cm. Cores were places in bins with site water in an environmental chamber to simulate field temperature on the day of collection. After a 3 hour period, the cores were capped underwater and attached to a peristaltic pump that flowed site water enriched with ~50 µM Na15NO3 for a 24 hour period. At the conclusion of the experiment, water samples were collected from each core and site water inflow to measure for nutrients and denitrification rates.

Instruments:

Membrane Inlet Mass Spectrometer (MIMS) was used to measure dissolved 29N, 30N, O2, Ar and N2

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