DOI: 10.6084/m9.figshare.12787268
title: Nitrogen (NO3-, N2O) isotope and isotopomer data from a eutrophic, tidal stream in Lismore, NSW, Australia

description: This study was carried out in a sub-tropical stream in the freshwater tidal zone in Lismore, NSW, Australia over eight days in April 2017. The stream is a tributary of the Wilson River in the Richmond River catchment. Surface water concentrations of dissolved gasses (N2O, CO2, CH4, O2, and 222Rn) were continuously logged, along with supporting parameters (conductivity, temperature, flow velocity, water depth) at one location within a 30 m x 4 m reach. Water samples were collected twice over each diurnal cycle from the surface and sub-surface (0.05 and 0.2 m depth) at nine locations across the reach. These samples were used to measure the concentrations of inorganic nitrogen (NH4+ and NO3-) and dissolved organic carbon, the isotopic composition of NO3- (d18O, d15N), the isotopic composition of N2O (site preference, d15N, d18O), and the isotopic composition of H2O (d18O).<br>Associated publication: Wells, N.S. and Eyre, B.D. 2021. Flow regulates biological NO3- and N2O production in a turbid sub-tropical stream. Geochim. Cosmochim. Acta.<br><br><br><br>For Logger Data file: <br>SampleDay: 24 hr periods during which grab samples were collected (corresponds to IDs in 2nd data table)pHconductivity (uS cm-1)Total dissolved solids (TDS) <br>Dissolved oxygen (as concentration, DO_mgL, and % saturation, DO_Sat)Temperature (in Kelvin, T_K, and celsius, T_C)Measured concentration of radon 222, in dpm per litre (Rn_dpm_l)Estimated concentration of radon 222 based on smoothed values in dpm l-1 (Rn_smooth) Stream height, in mm (depth_mm)Concentration of dissolved carbon dioxide in uM and mg C l-1 (CO2..uM., CO2_mgC_l)Concentration of methane in nM and ug C l-1 (CH4..nM., CH4_ugC_l)Concentration of dissolved nitrous oxide in nM, ug N l-1, and % saturation (N2O_nM, N2O_ug_N_l, N2O.sat)Calculated water-air N2O flux in ug N m-2 h-1 (N2Oflux) <br>Time (in seconds)Windspeed used to calculate N2O fluxes (Umeasured)Calculated surface water turnover time in days (SW_turnover)Stream slope, based on changed elevation (slope) Flow velocity calculated by smoothing measured values (v_smooth2) in mm_sStream discharge in m3 s-1, based on smoothed flow velocity and cross sectional area (Q_m3_s)Gas transfer velocity in m d-1 for N2O (k_avg)Categorisation of times as dark v light used for metabolism modelling (Dark_Light)<br>For Water Sample file: <br>Each data row corresponds to a unique water sample based on time x depth x width x length (Sample.ID)<br>Date gives the ID used to identify each 24 hr period that was sampled (corresponds to values in 'logging' datasheet)<br>Date and time of sample collection, though note collection took 2 - 3 hr (DateTime). Time is in AEST. <br><br>Samples were collected at predicted O2 maxima (Day, High) and minima (Night, Low), TideORTime<br>Time elapsed, in hours, since the first sample collection (TimeElapsed)<br>Location of sampling point over the reach length (Location), where A is upstream and C is downstream<br><br>Location of sampling point over the reach width (Rep), where 1 is the north bank, 2 is the centre, and 3 is the south bank<br>Mapped location of each sampling point in Easting & Northing<br>At each point samples were collected at three depths: from 20 cm below the surface of the water (SW), from 0.05 m below the sediment surface (S), and from 0.2 m below the sediment surface (HZ), as described in columns 'Depth' and 'Depth..m.'<br>Conductivity of SW and HZ samples (no data for S because sampled only with DET probes), in uS cm-1 (Conductivity)<br><br>Temperature of SW and HZ samples in Celsius (T)<br>pH of SW and HZ samples<br>Concentrations of NO3- in ug N l-1 (X.NO3..) <br><br>Concentrations of PO43- in ug P l-1 (X.PO4.)<br>Concentrations of NH4+ in ug N l-1 (X.NH4..)<br>Concentrations of dissolved organic carbon in SW and HZ samples in mM and mg C l-1 (X.DOC..mM, mg.DOC)<br>The isotopic composition of N-NO3- in delta units per mil v AIR (d15N.NO3)<br>Isotopic composition of O-NO3- in delta units per mil v VSMOW (d18O.NO3)<br>Isotopic composition, and standard deviation of measurement error, of deuterium in water in delta units per mil v VSMOW (dD.H2O, sd)<br>Isotopic composition, and standard deviation of measurement error, of oxygen of H2O in delta units per mil v VSMOW (d18O.H2O, sd.1)<br>Isotopic composition of nitrous oxide, including the ratio of 15/14 N in N2O (d15Nbulk.N2O), the abundance of 15N in the alpha position (alphaN), beta position (betaN), the 18/16O ratio (d18O.N2O), and the site preference of 15N (SP), for SW samples<br>