The SIO Isotope Use Committee (the IUC) reviews all experiments involving natural isotopes and radioisotopes on SIO research vessels, as well as isotopic labeling experiments using artificial isotopes and radioisotopes-IUC approval is required for isotope use. Because the activity amounts measured in natural samples can be as low as 10-12 to 10-15 of the activities commonly used in shipboard isotopic labeling experiments, the use of natural tracers such as Carbon-14 and Tritium can be problematic. In this context, natural stable isotope measurements can also be difficult. Given the need to maintain background levels of contamination, the US ocean sciences community attempts to keep research vessels of the UNOLS fleet as free of isotopic contamination as possible.
The principal objective of the SIO shipboard isotope use policy is to establish a practical and enforceable policy which minimizes the potential for isotopic contamination on all SIO vessels, while still recognizing and preserving the capabilities of these vessels with respect to the broad research interests of the UNOLS community. Natural levels of radioisotopes are many orders of magnitude lower than levels posing risks to human health. However, misuse of artificial radioisotopes for labeling protocols can potentially harm human health and the marine environment. Therefore, all isotope usage applications will be reviewed by the UCSD Radiation Safety Officer, who may impose conditions on any proposed isotope usage protocol.
Shipboard Isotope Use Guidelines
For these reasons, all protocols involving radioisotopes at concentrations beyond their natural backgrounds levels must be carried out in isotope usage vans. This work includes radioisotope handling, sample preparation, counting, autoradiography, etc. Areas on deck where incubations are carried out should be monitored for potential spills on a regular basis (e.g., after heavy use) and kept free of loose contamination.
Wearing of Personal Protective Equipment (gloves, safety glasses, labcoats) is mandatory as required based on severity of hazard. The vans must have a change area in which it is possible to put on booties upon entering and crossing the control area boundary. To prevent contamination of the ship, booties must be worn in the isolation van and the control boundary must be observed by science party members. Protective clothing must be supplied by the science parties.
Monitoring of potential radioactive spills is imperative. For these reasons the following procedures are considered to be of prime importance. Following cruises or a sequence of cruises during which radioisotopes have been used, a SWAB test of the isotope isolation vans, as well as the deck and laboratory areas will be carried out by the Miami Tritium Lab personnel. It is also required that isotope isolation vans have a "clean bill of health" from the Miami SWAB Group prior to loading. SWAB surveys can also be performed by UCSD EH&S personnel, with sample splits then forwarded to Miami. In case a SWAB test cannot be accomplished, the vans will be locked to prevent access by anyone until the tests can be performed.
Regular wipe and meter surveys by the isotope users must also be conducted, and should be carried out at least before the start of isotope work, once a week at a minimum during the cruise, after a suspected spill, and at the end of the cruise. Logs must be kept for each isotope van; these logs must be kept current and available, with all survey results recorded. Each investigator has the responsibility to complete and maintain a monitoring and spill log (available in each van). For users of stable isotopes no monitoring is possible, but a spill log is highly recommended.
For more details, check out the Scripps research vessel radiation safety training manual (PDF).
Radioisotope users are responsible for decontamination of any spills. Failure to remediate contamination events will result in a curtailment of the isotope user's access to SIO vessels.
Stable Isotope Work
For the use of stable isotopes no contamination tests are possible. This does not preclude chances of serious contamination, which may jeopardize work of other investigators. The stable isotope user is therefore required to submit a detailed protocol when a shiptime request is made. On the basis of this protocol the Isotope Use Committee shall make a recommendation on the particular program in consultation with the PI.
Sealed Source Instruments and X-ray Machines
It is necessary to apply to the Isotope Use Committee for the use of sealed source instruments on SIO vessels. This includes Ni-63 sealed sources used in electron capture gas-chromatographs, Cs-137 sources used in core sample analysis, as well as other instruments such as the Gamma Ray Neutron Density instrumentation (GRAPE). Current leak test certificates for these sources must be submitted with the Isotope Use Application institution. Any science parties bringing X-ray machines must also apply to the Isotope Use Committee for approval.
Submission of Isotope Use Plans
At the time an official request is made for the use of a research vessel of the SIO fleet it should be clearly indicated whether the use of isotopes is envisaged. It is realized that precise details cannot be made available a few years in advance, but it is expected that A "Request for Isotope Usage on SIO Vessels" form will be filed before the deadlines described below.
The application can be emailed (following the directions on the application) or sent by regular mail to:
Marine Operations Isotope Use Committee
c/o Ship Scheduling Office, 0210
Scripps Institution of Oceanography
La Jolla, CA 92093
The Ship Scheduling Office will then distribute copies of the application to the Committee for review. If this policy is adhered to, a more uniform treatment of requests will become possible.
For sealed source instruments a letter describing the instrument and its intended use should be addressed to the above address.
Isotope Usage Applications
- Must be filed at least ten weeks in advance. This allows the Isotope Use Committee to study the request and to formulate alternative plans if deemed necessary.
- Unanticipated, last-minute changes in types, amounts, and users of isotopes are, on occasion, unavoidable for the success of the research. The Isotope Use Committee will countenance such changes provided they are reasonable and meet with the approval of the Chief Scientist. All changes must be made by submitting a supplementary request for approval by the IUC.
- In case of potential scheduling changes it will be important to communicate immediately with the IUC, so that appropriate arrangements can be made.
It should be emphasized that the final responsibility for the proper usage of isotopes on SIO vessels rests not only with the isotope users but in particular with the Chief Scientist of each cruise.
Shipping of Isotopes or Sealed Source Instruments
We urge isotope users to ensure that all shipments of radioisotopes or of sealed source instruments to and from the ship are properly certified by the Radiation Safety Officer of their home institution. Legal and financial penalties for violation of applicable dangerous goods shipping regulations are substantial.