Stable Isotope Analytical Facility

NIWA's state of the art Stable Isotope Mass Spectrometry (IRMS) facility supports our research and commercial analyses, providing tailor-made solutions for various environmental and atmospheric questions. Our purpose-built facility houses high precision Thermo Fisher Scientific (MAT252, MAT253 and Delta V Plus) and Isoprime mass spectrometers, equipped with peripheral devices capable of analysing carbon, nitrogen, oxygen, hydrogen and sulphur isotopes in air, water, organic and inorganic samples. 

Mass Spectrometry techniques and measurements 

[MD] indicates that methods development is required before this method is available to clients
  Analysis Instrument Peripheral Contact Person
Air d13C of CO2 in air MAT-252 GC-IRMS Gordon Brailsford
  d13C of CO2 in air Delta V Plus Gasbench II & Precon [MD] Sarah Bury
  d18O of CO2 in air MAT-252 GC-IRMS Gordon Brailsford
  d18O of CO2 in air  Delta V Plus Gasbench II & Precon [MD] Sarah Bury
  d13C of CH4 in air MAT-252 GC-IRMS Gordon Brailsford
  d13C of CH4 in air Delta V Plus Gasbench II & Precon Sarah Bury
  d2H of CH4 in air Delta V Plus Gasbench II & Precon [MD] Sarah Bury
  d15N of N2 in air Delta V Plus Gasbench II & Precon [MD] Sarah Bury
  d15N of N2O in air Delta V Plus Gasbench II & Precon
Sarah Bury
  d18O of N2O in air Delta V Plus Gasbench II & Precon [MD] Sarah Bury
  d18O of O2 in air Delta V Plus Gasbench II   [MD] Sarah Bury
Carbon Dioxide d13C of CO2 MAT-253 Dual Inlet Gordon Brailsford
  d18O of CO2 MAT-253 Dual Inlet Gordon Brailsford
Carbon Monoxide d13C of CO MAT-252 Dual Inlet Gordon Brailsford
Nitrous Oxide d15N of N2O Delta V Plus Gasbench II & Precon [MD] Sarah Bury
  d18O of N2O Delta V Plus Gasbench II & Precon [MD] Sarah Bury
Water d2H of water Delta V Plus Gasbench II/TCEA Sarah Bury
  d18O of water Delta V Plus Gasbench II/TCEA Sarah Bury
  d18O of dissolved oxygen in water Delta V Plus Gasbench II [MD] Sarah Bury
  d13C of DIC* Delta V Plus Gasbench II Sarah Bury
  d15N of dissolved N2 in water  Delta V Plus Gasbench II Sarah Bury
Carbonates d13C of carbonate MAT 253 Kiel IV Andrew Kingston
  d13C of carbonate Delta V Plus Gasbench II Sarah Bury
  d18O of carbonate MAT 254 Kiel IV Andrew Kingston
  d18O of carbonate Delta V Plus Gasbench II Sarah Bury
Organics (tissue, filters, sediment) d13C of organics Delta Plus/Delta V Plus NA1500/Flash 2000 EA Sarah Bury
  d15N of organics Delta Plus/Delta V Plus NA1500/Flash 2000 EA Sarah Bury
  d34S of organics Delta Plus/Delta V Plus NA1500/Flash 2000 EA [MD] Sarah Bury
  d18O of organics Delta V Plus TCEA Sarah Bury
  d2H of organics Delta V Plus TCEA Sarah Bury
Compound Specific Isotope Analysis d15N of Amino Acids Delta V Plus GC-Isolink Brittany Graham/Andrew Kingston
  d13C of Amino Acids Delta V Plus GC-Isolink Brittany Graham/Andrew Kingston
  d13C of Fatty Acids Delta V Plus GC-Isolink Brittany Graham/Andrew Kingston
  d13C, d15N or d2H of additional compounds Delta V Plus GC-Isolink [MD] Brittany Graham/Andrew Kingston
* DIC dissolved inorganic carbon

Delta V Plus

Gasbench II & Precon

Our analytical facility generates isotope data which supports numerous research areas, which link into the following National Centres within NIWA: Aquaculture; Climate, Atmosphere & Hazards; Coasts and Oceans; Fisheries; Freshwater & Estuaries.

  • Atmospheric concentrations, emissions and chemistry
  • Trace gas emissions & processes
  • Climate Change
  • Natural Hazards
  • Hydrology
  • Biogeochemistry
  • Paleoclimate
  • Palaeoceanography
  • Paleoecology
  • Ecology (Marine/Terrestrial/Riverine/Lake - trophic studies, animal migration, ecosystem form and function)
  • Fisheries management
  • Aquaculture
  • Conservation & restoration
  • Agriculture and Forestry
  • Nutrient chemistry, cycling and budgets
  • Pollution studies (source apportionment- atmospheric, nutrient, sediment, chemical and water tracking)
  • Provenance and authentication (forensics, product authentication)
  • Energetics
  • Animal nutrition and physiology
  • Plant physiology
  • Soil processes
  • Biological and physical rate process measurements (e.g. primary productivity, nitrogen fixation, nutrient uptake)
  • Historical changes in environment (chronological sampling of archived samples, or micro-sampling of material with chronological growth structure – e.g. tree rings, fish otoliths, animal teeth)

Atmospheric Greenhouse gas studies 

Atmospheric greenhouse and trace gases are measured on the MAT252 and MAT253 utilising both dual inlet and continuous flow. While paleo-atmospheres are studied from ice cores on the Isoprime using a continuous flow technique.

NIWA operates Thermo Scientific MAT252 and MAT253 isotope ratio mass spectrometers in a purpose-built laboratory at Greta Point, Wellington. These instruments are fitted with both continuous flow and dual inlet systems and have been modified to provide precise analyses for various aspects of the environmental research undertaken by NIWA and its clients. In particular, modifications have been made to enable high-precision determinations of δ13C in the atmospheric greenhouse gases, carbon dioxide (CO2) and methane (CH4), as well as the trace gas carbon monoxide (CO). These data have been widely used in studies of the source structure of the gases as well as models examining global climate change.

Carbon dioxide is currently increasing in the atmosphere. While precise concentration measurements allow us to track this increase, it is stable isotopes that allow us to observe how the composition of the atmospheric CO2 is changing. The CO2 analyses involve the online separation of whole air on a chromatographic column, before measurement in a continuous flow mode. These analyses provide both δ13C and δ18O, with precisions of 0.02‰ and 0.04‰ respectively.

Methane is the second most important greenhouse gas. Research into the stable carbon isotope seasonality and variability provides insight into methane sources, atmospheric processes and transport. Methane isotope analyses at NIWA involve either off-line preparation for high precision, or are made on-line for small samples. The high precision analyses are aimed at resolving the small seasonal cycle (about 0.2 ‰) observed at southern mid-latitudes. Our off-line preparation achieves repeatability of better than 0.02‰ since the early 1990s. Scientific findings, based on this time series, include the characterisation of a previously unknown methane sink, and a recent shift in global methane sources from fossil fuels to wetlands or agriculture.

The study of paleo-atmospheres using ice cores is constrained by very small sample sizes. For this reason the continuous flow Isoprime is fitted with a pre-concentration and combustion interface, allowing δ13CH4 analyses to be made on a kilogram of ice.

Contacts – Atmospheric greenhouse gas studies

Ross Martin

Gordon Brailsford


Related greenhouse gas publications.

Stable Isotopes in Carbonates 

Carbonates are studied using the MAT252 and MAT253 which are equipped with Thermo Scientific Kiel (III & IV) devices, providing automated high-precision determinations of δ13C and δ18O in individual foraminifera and other carbonate samples.

NIWA is a leading institute in New Zealand doing high resolution analysis of stable isotopes in carbonates to identify environmental change over timescales of tens to thousands of years. We use these techniques on materials as diverse as foraminfera, shells, fish earbones, and limestone structures in caves. These analyses provide both δ13C and δ18O, with precisions of 0.04‰ and 0.08‰ respectively.

Planktonic foraminifera are single-celled organisms which secrete their tests using oxygen and carbon from the water in which they live. Isotopic analysis on these, and on deepsea corals and brachiopods, tells us much about how the marine climate has changed in the past, including relatively abrupt changes in ocean circulation.

Locked inside speleothems, including stalactites and stalagmites, is a historical record of heavy rain seeping into caves. Isotope analysis here helps define risk assessment models (e.g., for tropical cyclones) and improves understanding of climate changes.

Stable isotopes in coastal fauna such as paua shells provide a picture of local climate variability and help us estimate paua age and growth rate; information vital for assessing the sustainability of these coastal fisheries.

Isotope analysis of fish otoliths (earbones) is clarifying the life histories of some significant commercial species.

These analyses all provide critical information for understanding freshwater, marine, and terrestrial ecosystems, particularly with respect to historical climate change and environment and biology of marine organisms. It is now possible to study past changes in the ocean and climate, provide improved data for climate modelling, and help predict the response of the ocean to climate change. Also to reconstruct seasonal profiles of bygone winters and summers, unravel geographic fish migration patterns and life histories, or even derive daily records of climate for the Miocene (20 Ma).

Contacts – Carbonate Analysis

Dr Andrew Kingston Ph. +64 4 386 0836


A selected list of publications illustrates NIWA's recent research using a Kiel device, which provides automated high-precision determinations of δ 13C and δ 18O in individual foraminifera and other carbonate samples.

Mass spectrometry-related publications 

Environmental Stable Isotope Analysis

Stable isotope analyses from our Delta Series mass spectrometers and their peripherals (Elemental analyser (EA), Gasbench II, Precon and Thermo Chemical Elemental Analyser (TCEA) have wide-ranging applications in many areas of environmental research.

Elemental analysers linked to Thermo Fisher Scientific DeltaPlus and Delta V Plus mass spectrometers enable us to analyse carbon and nitrogen concentrations and isotope ratios in solid samples from freshwater, marine and terrestrial environments with a focus on ecological studies. In addition, we are able to analyse oxygen and hydrogen in solid and liquid samples using the TCEA, and hydrogen, carbon and nitrogen in water and gas samples on the Gasbench II. This has now widened our scope to include research into hydrologcial, palaoenvironmental and trace gas studies.

Our EA system is optimised to analyse extremely low quantities of nitrogen to down to 2µg N content, enabling the analysis of microscopic samples. 

In ecological studies, stable isotopes are an extremely useful determinant of the trophic status of organisms and an indicator of their diet. There is a slight variation in C and N stable isotope values between an organism and its food source, which has resulted in the statement "You are what you eat, plus or minus a few per mil". Nitrogen isotopes are the strongest indicators of trophic status, showing a step-wise enrichment in 15N of about 3–4‰ at each successive trophic level. By combining C and N isotopic values of a consumer, it is possible to deduce its likely dietary intake and resolve complex food web structures.

Nitrogen isotope values can be utilised to identify different sources of nitrogen and indicate pollutant pathways. Several natural processes fractionate nitrogen, e.g. inorganic nitrogen assimilation, nitrogen fixation, nitrification, denitrification, ammonification, and other processes of nitrogen metabolism.

A valuable application of stable isotopes is that of tracer or enrichment studies. Such studies enable rates of processes to be directly measured by the incorporation of an artificially-enriched stable isotope. This is an extremely powerful experimental method in environmental studies.

Research Projects

Some examples of specific stable isotope research that NIWA is currently involved in include:

  • Antarctic Ecology: Antarctic toothfish trophic ecology and migration; Distribution, morphology and ecology of Macrourus whitsoni and M. caml (Gadiformes, Macrouridae) in the Ross Sea region; Diet and trophic niche of Antarctic silverfish (Pleuragramma antarcticum) in the Ross Sea, Antarctica.
  • Cetecean studies: Dietary studies reveal that male humpback whales do not just each krill; Population, habitat and prey characteristics of blue whales foraging in the South Taranaki Bight; The influence of fasting and opportunistic feeding on the stable isotope values of baleen whale skin; New insights into the feeding ecology of Hector’s dolphins (Cephalorhynchus hectori) inferred from stable isotope mixing models; Demography and ecology of southern right whales wintering at Campbell Island, New Zealand.
  • Megafaunal Ecology: Highly migratory species diet and movement studies
  • Freshwater ecology: Tracing sewage-derived organic matter into a shallow groundwater food-web using stable isotope and fluorescence signatures.
  • Marine and freshwater nutrient dynamics: Response of surface nutrient inventories and nitrogen fixation to a tropical cyclone in the South-West Pacific; Regenerated primary production dominates in an upwelling shelf ecosystem, northeast New Zealand;  Sedimentary nitrogen uptake and assimilation in the temperate zooxanthellate sea anemone Anthopleura aureoradiata.Marine and freshwater ecosystem structure ;
  • Deep Sea Ecology: High intraspecific variability in the diet of a deep-sea nematode: Stable isotope and fatty acid analyses of Deontostomatridentum on Chatham Rise, Southwest Pacific
  • Marine Hazards: the effects of the Kaikoura earthquake on ecosystem structure in the Kaikoura Canyon
  • Fish studies: Variation in morphology and life history strategy of an exploited sparid fish; Matching and mismatching stable isotope (δ13C and δ15N) ratios in fin and muscle tissue among fish species – a critical review; Effect of ingestion on the stable isotope signature of marine herbivorous fish diets.
  • Seabird ecology. e.g. Sex-specific foraging during parental care in a size monomorphic seabird, the Australasian gannet (Morus Serrator); Does low seasonality drive reduced duration of migration in temperate brown skuas?; Feeding Ecology of Black Backed Gulls – changes over time; Breeding Mottled Petrel feeding ecology and distributions on Cod Fish Island; Fluttering shear water diet and movements in Hauraki Gulf; Diving Petrel dietary studies; Wintering in the sun: niche partitioning by three non-breeding Pterodroma petrel species in the equatorial Pacific Ocean; Stable isotope signatures delineate the non-breeding distributions of sooty shearwaters Puffinus griseus in the North Pacific Ocean; Higher trophic level prey does not represent a higher quality diet in a threatened seabird: implications for relating population dynamics to diet shifts inferred from stable isotopes; Foraging ecology and choice of feeding habitat in the New Zealand Fairy Tern, sternula nereis davisae; Contemporary and historical separation of transequatorial migration between two genetically-distinct seabird populations;  Foraging ecology of the Cook’s petrel Pterodroma cookie during the austral breeding season: a comparison of its two populations; A stable isotopic investigation into the causes of decline in a sub-Antarctic predator, the rockhopper penguin Eudyptes chryoscome.
  • Marine microbial community structure and function
  • New Zealand’s ocean carbon cycle model: understanding marine carbon cycling and food-webs to predict climate change effects.
  • Terrestrial Ecology: Foliar and soil nitrogen and δ15N as restoration metrics at Pūtaringamotu Riccarton Bush, Christchurch city; Aborigine-managed forest, savanna and grassland: biome switching in montane eastern Australia.
  • Gas Emissions: Mitigation via chemical di-nitrogen formation: Exploring ways to remove nitrogen while bypassing nitrous oxide emission aims to develop cost effective techniques for removing reactive N and reducing N2O emissions in grazed agricultural systems.
  • Climate studies: Reconstructing past variations in precipitation and temperature in New Zealand on decadal to millennial timescales through the analysis of skeletal remains of heads of midge larvae; Climate reconstruction using the New Zealand freshwater bivalve Echyridella menziesii from Lake Rotorua.
  • Deep Sea Geochemistry: Isotopic studies of methane seeps – tracing sources of carbon.
  • Terrestrial ecology: Feeding ecology of ants
  • Tracking sediment sources: Using fatty acid compound specific isotope analysis

Contact – Delta Series Facility

We provide competitive rates for commercial analysis of stable isotope samples and are enthusiastic about research collaboration. For information, including enquiries relating to collaborative research or commercial analyses, contact:

Sarah Bury, Ph. +64 4 386 0347.

Delta Series Publications

A selected list of publications illustrates NIWA’s recent research using the DeltaPlus mass spectrometer.

Mass spectrometry-related publications 

Sarah Bury and Brittany Graham - Stable Isotope Environmental Laboratory. [Photo: Dave Allen, NIWA]
NIWA’s New Wave micromill is used to prepare microsamples for chemical and isotopic analysis. Complex structures can be sampled with submicron stage resolution and positional accuracy. Pictured clockwise top to bottom are: speleothem (being milled), bamboo coral sections, a galaxid otolith, a pair of pilchard otoliths. [Photo: NIWA]
Sample gas is frozen back from the MAT253 after stable isotope analysis for later 14C analysis. [ Photo: NIWA ]
Dr Helen Neil checks samples for a 24 hour carbonate (Kiel and IRMS) stable isotope run. [Photo: Dave Allen, NIWA]
Compound specific isotope analysis (CSIA). [Photo: Sarah Bury, NIWA]
Thermo Chemical Elemental Analyser (TCEA). [Photo: Sarah Bury, NIWA]
Gasbench II, GC-PAL autosampler and Precon Unit attached to a Delta V Plus MS. [Photo: Sarah Bury, NIWA]
The Flash 2000 Elemental Analyser enables ultra low levels of N to be analysed in organic samples. [Photo: Sarah Bury, NIWA]
Flash 2000 EA, TCEA, Gasbench II. [Photo: Sarah Bury, NIWA]