Results from experiment examining 15N-labeled contaminants in commercial 15N2 gas: Particulate Nitrogen - The delta 15N of Dunaliella tertiolecta organic matter after growth in media equilibrated with 15N2 gas

Website: https://www.bco-dmo.org/dataset/547774
Version: 03 Feb 2015
Version Date: 2015-02-03

Project
» The Ocean Nitrogen Imbalance Paradox: Environmental Controls on the Denitrification Isotope Effect (15N2 Contamination)
ContributorsAffiliationRole
Granger, JulieUniversity of Connecticut (UConn)Principal Investigator
Dabundo, RichardUniversity of Connecticut (UConn)Contact
Rauch, ShannonWoods Hole Oceanographic Institution (WHOI BCO-DMO)BCO-DMO Data Manager


Dataset Description

The delta 15N of Dunaliella tertiolecta organic matter after growth in media equilibrated with 15N2 gas.

Refer to the following publication for more information:
Dabundo, R., Lehmann, M.F., Treibergs, L., Tobias, C.R., Altabet, M.A., Moisander, P.H., and Granger, J. 2014. The Contamination of Commercial 15N2 Gas Stocks with 15N–Labeled Nitrate and Ammonium and Consequences for Nitrogen Fixation Measurements. PLoS ONE, 9(10): e110335. doi:10.1371/journal.pone.0110335

See related datasets:
delta 15N NO3
delta 15N NH4
direct N2O
N2


Methods & Sampling

Data was acquired from an isotope ratio mass spectrometer using Isodat 3.0 software.

Particulate Nitrogen calculations:
The equation describing the linear regression of the standards' observed delta 15N PN and Assigned delta 15N (obs = x and assigned = y) was used to calculate delta 15N PN (y) of the samples from the uncorrected delta 15N (x).

Refer to the following publication for more information:
Dabundo, R., Lehmann, M.F., Treibergs, L., Tobias, C.R., Altabet, M.A., Moisander, P.H., and Granger, J. 2014. The Contamination of Commercial 15N2 Gas Stocks with 15N–Labeled Nitrate and Ammonium and Consequences for Nitrogen Fixation Measurements. PLoS ONE, 9(10): e110335. doi:10.1371/journal.pone.0110335

Summary of methods from Dabundo et al. 2014:
Reagents:
Four lecture bottles of 98+ at% 15N-labeled N2 gas were purchased from Sigma-Aldrich, three from lot # SZ1670V, and one from lot # MBBB0968V. Two 1L lecture bottles of 98+ at% 15N2 were purchased from Cambridge Isotopes from lot #’s I1-11785A and I-16727. One 1L lecture bottle of 98+ at% 15N2 was purchased from Campro Scientific from lot # EB1169V. Ammonium and nitrate solutions were prepared with salts or with solutions obtained from different distributors: sodium nitrate (NaNO3), potassium nitrate (KNO3), and ammonium chloride (NH4Cl) from Fisher Scientific; analytical-grade potassium nitrate from Fluka Analytical and a gravimetric solution of ammonium chloride from SPEX CertiPrep.

Dunaliella tertiolecta cultures:
The marine green alga Dunaliella tertiolecta was cultured in growth media equilibrated with 15N2 gas in order to ascertain the susceptibility of 15N-labeled gas contaminants to assimilation by non-N2-fixing organisms. Culture medium was prepared from filtered Long Island Sound sea water supplemented with 50 umol/L NaNO3, 36.3 umol/L NaH2PO4*H2O, and 107 umol/L Na2SiO3*9H2O, as well as f/2 trace metals and f/2 vitamins, added from filter sterilized stock solutions. Medium (200 mL) was dispensed in 250 mL stoppered glass bottles. Experimental treatment bottles were equilibrated overnight with 0.2 mL 15N2 gas from either a Cambridge Isotopes or Sigma-Aldrich lecture bottle. Following inoculation, cultures were left loosely capped and placed on a windowsill with exposure to natural light. Nitrate concentrations were monitored daily. Upon the complete depletion of nitrate, 8 days after inoculation, the cultures were harvested on pre-combusted GF/F filters. Filters were dried at 60 degrees C for 18 hours pending N isotopic analysis of the particulate nitrogen.

Particulate nitrogen isotope ratio analyses:
The d15N of particulate nitrogen (PN) was analyzed using a Costech Instruments elemental combustion system (model 4010) coupled to a Thermo Scientific Delta V Advantage IRMS. Analyses were standardized using L-glutamic acid reference materials, USGS-40, and USGS-41.


Data Processing Description

Samples with the same ID are replicated measurements.

BCO-DMO Edits:
- Modified parameter names to conform with BCO-DMO naming conventions;
- Denoted 'Control' and 'Standard' in the lot_number column;
- Replaced spaces with underscores.
- Replaced blanks (missing values) with 'nd' to indicate 'no data'.


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Data Files

File
particulate_N.csv
(Comma Separated Values (.csv), 2.14 KB)
MD5:430ecbf043312153d0c242ca3f76d535
Primary data file for dataset ID 547774

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Parameters

ParameterDescriptionUnits
lecture_bottle

Identifier of the lecture bottle of 15N-labeled N2 gas.

dimensionless
lot_number

Lot number of the 15N-labeled N2 gas; or 'Control' or 'Standard' for controls and standards respectively.

dimensionless
solution

Solution volume.

milliliters (mL)
headspace

Headspace volume.

milliliters (mL)
N2_injection

Quantity of 15N-labeled N2 gas supplemented in the headspace.

milliliters (mL)
sample_ID

Sample identification number.

dimensionless
initial_NO3

Initial concentration of nitrate (NO3).

micromolar (uM)
final_NO3

Final concentration of nitrate (NO3).

micromolar (uM)
uncorr_d15N

Uncorrected delta 15N.

per mille (‰)
d15N_PN

delta 15N of particulate Nitrogen (PN).

per mille (‰)
assigned_d15N

Assigned delta 15N.

per mille (‰)


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Instruments

Dataset-specific Instrument Name
Costech Instruments 4010
Generic Instrument Name
CHN Elemental Analyzer
Dataset-specific Description
The delta 15N of particulate nitrogen (PN) was analyzed using a Costech Instruments elemental combustion system (model 4010) coupled to a Thermo Scientific Delta V Advantage IRMS.
Generic Instrument Description
A CHN Elemental Analyzer is used for the determination of carbon, hydrogen, and nitrogen content in organic and other types of materials, including solids, liquids, volatile, and viscous samples.

Dataset-specific Instrument Name
Thermo Scientific Delta V Advantage IRMS
Generic Instrument Name
Isotope-ratio Mass Spectrometer
Dataset-specific Description
The delta 15N of particulate nitrogen (PN) was analyzed using a Costech Instruments elemental combustion system (model 4010) coupled to a Thermo Scientific Delta V Advantage IRMS.
Generic Instrument Description
The Isotope-ratio Mass Spectrometer is a particular type of mass spectrometer used to measure the relative abundance of isotopes in a given sample (e.g. VG Prism II Isotope Ratio Mass-Spectrometer).


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Project Information

The Ocean Nitrogen Imbalance Paradox: Environmental Controls on the Denitrification Isotope Effect (15N2 Contamination)


Description from NSF award abstract:
This study will test the sensitivity of the amplitude of the denitrification isotope effect to culture conditions pertinent to the ocean environment. The isotope effect amplitude will be explored with respect to electron donor, trace oxygenation, and temperature, in both batch and continuous culture experiments of denitrifiers. The proposed work will also involve measurements of the enzymatic isotope effect of the respiratory nitrate reductase of denitrifiers, measurements of its enzymatic activity among cultures, and examination of cellular nitrate transport kinetics of denitrifying strains. The experiments are designed to reveal the physiological basis of the modulation of the isotope effect amplitude, which will further resolve this manifestation in the environment.

In regards to the broader significance and importance of this study, these new experimental data will provide a basis for integration of nitrogen isotope dynamics in ocean models to test how key environmental parameters can affect the global ocean distribution of nitrogen isotopes.



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Funding

Funding SourceAward
NSF Division of Ocean Sciences (NSF OCE)
NSF Division of Ocean Sciences (NSF OCE)
Swiss National Science Foundation (SNSF)

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