GNIR — Frequently Asked Questions

Who operates GNIR stations and produces the isotope data?

GNIR stations are usually operated by hydrological services within the framework of national or basin-scale river observation networks, or by water research institutions and individual researchers, and even private citizens. Similarly, these organisations and researchers often produce the corresponding isotope data. GNIR stations are generally monitored for stable water isotopes (18O, 2H), and a subset for radioactive tritium (3H).

Will the IAEA provide sampling supplies and conduct the isotopic analyses?

Depending on the circumstances, the IAEA may be able to provide in-kind support through sampling bottles and analytical services for H/O isotopes. Typically, we rely on national contributors to conduct their river sampling and isotopic assays. However, we are happy to assist with technical advice or get you in touch with potential collaborating agencies in your country or region.

Does the IAEA provide grants to run a GNIR station?

No. Participation in GNIR is voluntary. The IAEA may be able to provide some in-kind support, as noted above.

I want to contribute isotope and river data to GNIR. Does the IAEA have a submission spreadsheet?

All data contributions are warmly welcomed! Ensuring smooth data transfer avoids transcription errors, and for this reason we will provide a submission Excel template with data headers. Please contact us first if you wish to contribute data at

Are there river water sampling guidelines for isotopes?

Protocols for the collection of various isotopes and water chemistry from rivers are subject to the aims of the researcher, sampling and analytical resources, and project objectives. The current GNIR CRP will provide general guidelines for various isotopes in the future on this website.

For 18O/2H sampling, a high quality 25-50 mL HDPE plastic bottle is sufficient. The sample bottle should be rinsed out with the filtered sample, filled to the top and tightly capped. Samples should be stored at room temperature, preferably in dark to reduce biogeochemical reactions. In case of transportation, take precautions to ensure the samples do not freeze or leak. If glass bottles are used, a small headspace should be left, to avoid that bottles break during accidentally freezing.

Are there criteria for river water sampling sites?

Some basic suggestions are proposed for river sample collection sites to obtain the minimum required information and optimise spatio-temporal data coverage. These suggestions will be subject to revision based on the outcome of the current GNIR CRP.

• For rivers that discharge to oceans or lakes, samples should be taken above the delta or tidal reach so that the effects of lake or ocean intrusion are avoided.

• It is recommended to sample upstream of an incoming tributaries in order to avoid tracing of incomplete mixed river water. Ideally, river samples are taken midstream (e.g. from a bridge), depending on access.

• River samples should be taken at the mouth, headwaters, and the middle reaches. Sampling design will depend on the size of the catchment and project logistics.

• The recommended sampling interval for rivers is monthly, but this can be informed by seasonal stages of the hydrograph (base flow, high flow, under ice, spring melt, etc.) and logistical as well as safety constraints (avoid dangerous floods and unsafe ice conditions). Generally, base flow and high discharge condition samples are very useful, as well as intermediate river stages if possible.

• Ideally, river samples are collected near gauging stations in order to provide corresponding discharge or biogeochemical information to interpret the isotope data.

• The proper design of a sampling station might be facilitated with a survey of flow distribution through a transect at the targeted emplacement. Low flows might be measured by in-stream wading measurements and high flows, from a bridge with standard bridge equipment or an Acoustic Doppler Current Profiler

How are data from the GNIR database cited?

Please cite the GNIR database:

Global Network of Isotopes in Rivers

and also acknowledge or cite data attribution (e.g. publications or the organisation that contributed the data to GNIR as provided in data download). Proper data attribution helps to credit the many researchers and an institution involved, and thereby affirms the importance of their work and contributions.

How is the data quality in the GNIR database ensured?

GNIR data is routinely screened for completeness of the following attributes: i) spatial information like station coordinates, site information, and elevation, etc., ii) temporal and sampling-related information (sampling date and methods, field data), and iii) analytical isotopic results with outlier detection and comparisons with local meteoric water lines (although isotopic compositions of river water makes the establishment of data rejection criteria more difficult than for GNIP).

• In order to ensure analytical performance of the laboratories involved, labs are encouraged to partake in IAEA inter-comparison exercises like WICO (Water Isotope Intercomparison) organised by the IAEA every 3-4 years. IAEA will organise similar inter-comparison exercises whenever needed for other isotope studies.

Do you have a "Citizen-Science" program for GNIR? Or must I be a scientist?

Citizen-science sample collection efforts are always welcomed! As noted above, the IAEA may be able to provide in-kind and analytical support for citizen science efforts adding to GNIR. Generally a 2-3 year commitment of monthly to quarterly sampling is preferable. Please contact us if you have a river in mind that you may be able to sample to make a citizen science contribution.

I am interested in becoming involved in GNIR. Is my river of interest?

All riverine contributions to GNIR, regardless of scale, are useful for adding to the global isotope database. Please contact us if you have any questions about adding a river or stream.

One of the aims of GNIR is to target the top 50 rivers of the world, as they contribute over half of the terrestrial fluxes to the world's oceans. A list of targeted rivers is provided below. Any efforts on the rivers listed below are especially needed, but participants are also encouraged to pay attention to smaller catchment systems.

Africa: Congo, Niger, Ogooue, Zambezi, Nile, Volta, Limpopo

Asia: Ganga-Brahmaputra-Meghna, Changjiang/Yangtze, Yenisei, Lena, Mekong, Irrawaddy, Ob, Amur, Xi Jiang (Zhujiang/Pearl), Salween, Hai Ho (Hai He/White), Kolyma, Hong (Red River / Song Koi), Khatanga, Godavari, Indus, Shatt-el-Arab (Tigris-Euphrates), Huang He (Yellow)

Europe: Volga, Danube, Svernaya Dvina, Rhône, Rhine, Elbe, Dnjepr, Don, Pechora

North America: Mississippi, St. Lawrence, Mackenzie, Columbia, Yukon, Fraser, Rio Grande

South America: Amazon, Orinoco, Paraná, Tocantins, Magdalena, Uruguay, Patía, São Francisco

South-West Pacific: Fly, Mamberamo, Sepik, Kapuas, Murray-Darling, Purari

Responsible/Contact: Isotope Hydrology Section | Last update: 03 February 2014