Nitrous oxide emissions from eroding high-center polygons in an Arctic coastal wetland, 2021.

This data contains nitrous oxide (N₂O) and carbon dioxide (CO₂) fluxes from eroding polygon features located in a coastal wetland near Utqiaġvik, Alaska on the Barrow Environmental Observatory (BEO). Static chamber fluxes were measured with a Gasmet GT5000 Terra Fourier transform infrared (FTIR) greenhouse gas analyzer (GGA) and a clear, cylindrical polycarbonate chamber (50 cm height and 20cm diameter) in a closed system at a 1Hz sampling rate. The FTIR GGA is capable of measuring concentrations by scanning the full infrared spectrum and calculating the concentrations of each gas in the sample based on its absorption.Chamber collars were made of PVC (15 cm height and 20 cm diameter) and installed 3 days prior to greenhouse gas measurements at a depth of 10 cm. Fluxes were measured at 30 locations – 10 vegetated replicates and 20 unvegetated soil replicates – whenever weather permitted during July 2021 for a total of 263 measurements. Ancillary measurements included soil temperature, bulk density, thaw depth, soil water content, stable isotope ratios, and carbon to nitrogen (C:N) ratios. Soil water content, soil surface temperature, and thaw depth were measured at the time of each chamber measurement at the flux collar throughout the study period (n = 263). Soil water content was measured with a Fieldscout 300 TDR soil moisture meter. Soil surface temperature was measured with an infrared thermometer. Depth of thaw was measured with a small diameter metal rod. Bulk density was measured from soil samples from the top 15 cm of the soil column, collected at each collar location at the end of the study period, for a total of 30 samples. Soil samples were dried for 24 hours at 60 °C in a drying oven and results expressed as weighed per unit volume. 

Soil samples from the top 15 cm of the soil column were removed at both vegetated and unvegetated areas near where fluxes were measured using a handheld soil sampling corer (7 cm diameter, 15 cm height) at the end of the experiment. Soil samples consisted of four profiles with three depths for a total of 24 samples. Samples were then separated into 5 cm depth segments (to check relationship with depth) using a band saw, placed in a drying oven at 65 C for 48 hours, then homogenized with a vibratory ball mill. The abundance of ¹⁵N, ¹³C, and C:N ratios were measured using a continuous flow isotope ratio mass spectrometer (IRMS, Delta V Advantage, Thermo Fisher Scientific). A laboratory standard (USGS41, L-glutamic acid) was used as a reference material for the calibration of stable carbon and nitrogen measurements. Isotope values are reported in standard δ notation (‰) relative to Vienna PeeDee Belemnite (δ ¹³C) and air-N2 (δ ¹⁵N). 

Files in this repository:

This dataset consists of four files: (1) 'chamber_fluxes.csv' contains measurements for individual flux data; (2) 'collar_means.csv' contains measurements averaged per collar location and include discrete bulk density measurements; (3) 'soil_content.csv' contains measurements of carbon content, nitrogen content, and isotope content; and (4) 'metadata.csv' contains a description of column headers and units.