During recent years there has been great concern about maintaining the utility of our research fleet for the study of natural isotopes and radioisotopes in the marine environment, while at the same time trying also to maintain the usefulness of the fleet for isotopic labeling experiments in which artificial isotopes and radioisotopes are used. Especially at risk is the use of natural radioisotopic tracers such as carbon-14 and tritium, where the amounts measured in natural samples can be as low as 10-12 to 10-15 of the amounts commonly used in shipboard isotopic labeling experiments, but there are also problems for natural stable isotope measurements. Because of this extraordinarily high potential for contamination, there has been an ongoing effort in the US ocean sciences community to keep at least a few research vessels of the UNOLS fleet as free of isotopic contamination as possible.
The policies outlined in this document are intended as guidelines, the Isotope Usage Committee being well aware that "common sense" must remain an important component in all shipboard research decisions. Isotope users are urged to provide as detailed a protocol as possible for their intended isotope use.
At Scripps, R/V Melville and R/V Revelle have been designated as "clean ships" with respect to isotopic contamination, and special conditions and restrictions apply to any use of artificial radioisotopes and stable isotopes on these vessels. Less stringent conditions and restrictions apply to the other ships of the Scripps fleet. It is important to recognize that the principal objective of the Scripps shipboard isotope usage policy is to establish a practical and enforceable policy which minimizes the potential for isotopic contamination on all Scripps vessels, while still recognizing and preserving the capabilities of these vessels with respect to the broad research interests of the UNOLS community.
Safety concerns are usually not at issue during most common isotope uses on board ships. Natural levels of radioisotopes that are subject to contamination are many orders of magnitude lower than the level which poses risks to human health. Nonetheless any isotope usage permit will be subject to evaluation by radiation safety officers from the UCSD Environmental Safety Program, who may express special concerns about any proposed isotope usage protocol.
R/V Melville and R/V Roger Revelle
We envisage that R/V Melville and R/V Roger Revelle in particular may be used in the future for natural isotope tracer studies, (e.g., 14-C, 3-H). For these reasons, all work involving radioisotopes at concentrations beyond their natural levels, must, in principle, be carried out in isotope usage vans. This work includes isotope handling, 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 regular hosing down of these areas is strongly encouraged.
It is required that isotope isolation vans have a "clean bill of health" from the Miami SWAB Group prior to emplacement on R/V Melville and R/V Roger Revelle. Wearing of special footwear in the vans (available onboard ship) is mandatory. The vans must, therefore, have an area in which it is possible to change footwear and clothes (e.g., foul weather gear). The usefulness of this rule is clear from a recent event in which an isotope isolation van on R/V Melville was heavily contaminated but, partially because of the changing of footwear, this contamination was not spread throughout the ship.
Circumstances may occur in which the above procedures will place an undue burden upon a scientific party, in that some experiments may not be feasible within the constraints of the policy, or that, while feasible, meeting the policy would place an unreasonable logistic burden upon the program. In such a case a detailed justification will be required outlining a special protocol indicating a awareness of the potential effects on contamination outside the working area of the vans and a proposed monitoring program to detect potential spills. The Isotope Committee in that case may stipulate conditions associated with a waiver.
Monitoring of potential radioactive spills is imperative. For these reasons the following procedures are considered to be of prime importance. At the end of each leg of R/V Melville and R/V Roger Revelle 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 SWAB test laboratory. If for some reason (e.g., remoteness or inaccessibility of the ship) the SWAB operation cannot be carried out by the Miami group, the resident marine technician, in collaboration with the PI, could be requested to carry out the SWAB according to Miami instructions. Samples can then be forwarded to Miami. In case a SWAB test cannot be accomplished, it will be imperative to lock the vans to access by anyone until the tests can be performed. This is particularly a necessity because of clean-up responsibilities of the parties involved in the radioisotopes usage. If two subsequent legs will have radioisotope usage with different investigators, then a SWAB test must be carried out between these legs. The above test program does not preclude the requirement of regular swab tests by the isotope users, which 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 and for the chronology of isotope usage on R/V Melville and R/VRoger Revelle. These logs must be kept available in each isotope van.
Other Scripps Ships
On other Scripps vessels, i.e., R/V R. G. Sproul and R/V New Horizon, all use and handling of radioisotopes and stable isotopes will be restricted to assigned isotope vans. In some special cases, with the permission of the Isotope Usage Panel, work involving small quantities of isotopes or dilute solutions may be carried out in the laboratories of these vessels (e.g., scintillation counting, microautoradiography, chromatographic analysis of labeled compounds).
Normally, work on the smaller ships requires a multitude of tasks making changing footwear often too cumbersome. For these reasons, there will be no rigid requirement for special footwear in the isotope isolation vans, although such usage is encouraged whenever possible. With the often tight scheduling of cruises, there may, however, occur conflicting circumstances. For instance, there may occur usage of the ship for natural radioisotope occurrences immediately after the intended isotope usage cruise. In such a case the Isotope Committee can invoke the footwear ("booties") rule after consultation with the PI's involved. Timely requests for isotope usage are of importance at all times, so that scheduling can be done well in advance.
Monitoring as prescribed by the UCSD Radiation Officer will remain a requirement, but we advocate also the testing of larger surface areas as suggested by the Miami SWAB group. The Miami SWAB test is described in RSMAS Technical Report No. TR-84-001, which is available in each isotope isolation van.
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.
In order to emphasize the concern of the Isotope Usage Panel about isotope spills and also to protect Scripps from incurring extensive costs for cleanups, a statement of clean-up responsibility will be provided on the original isotope usage form and must be signed prior to the intended cruise. Cleanup cost can be drastically reduced if the isotope users carry out the bulk of this cleanup work. A breach of the clean-up commitment will result in a curtailment of the isotope user's access to Scripps vessels. Thus the isotope users assume full liability for cleanup costs incurred by Scripps as a consequence of their work.
Stable Isotope Work
For the use of stable isotopes no contamination tests are possible. This, of course, does not preclude chances of serious contamination, which may jeopardize work of other investigators. The isotope user, however, is required to submit a detailed protocol for the isotope usage envisioned at the time a shiptime request is made. On the basis of this protocol the Isotope Usage Panel shall make a recommendation on the particular program in consultation with the PI.
Sealed Source Instruments
It is necessary to apply for the use of sealed source instruments on Scripps vessels. Under this item we classify electron capture gas-chromatographs, as well as other instruments such as the Gamma Ray Neutron Density instrumentation (GRAPE) for core porosity measurements. It is necessary to test this equipment for potential leakage prior to use on the ship. This can be certified by the appropriate Radiation Officer at the user's home institution.
Submission of Isotope Use Plans
At the time an official request is made for the use of a research vessel of the Scripps fleet it should be clearly indicated whether the use of isotopes is envisaged. If so, an information package will be mailed to the requestor informing him/her of regulations for isotope usage. A preliminary plan should be submitted at that time by letter to the Chairman of the Isotope Usage Panel. 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 SIOVessels" form must be filed before the deadlines described below. This request should be addressed as follows:
Marine Operations Isotope Usage Panel
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 Chairman of the Isotope Usage Panel and to the UCSD Radiation Safety Officer 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 it's intended use should be addressed to the above address.
Isotope Usage Applications
- R/V Melville and R/V Roger Revelle - at least THREE months in advance. This allows the Isotope Usage Panel to study the request and to formulate alternative plans if deemed necessary.
- Other Scripps vessels: TWO months in advance, unless much larger scale usage is planned (multiple users, etc.). In the latter case, the deadline shall be six months prior to the cruise.
- Unanticipated, last-minute changes in types, amounts, and users of isotopes are, on occasion, unavoidable for the success of the research. The Isotope Usage Panel 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 Isotope Usage Panel.
- In case of potential scheduling changes it will be important to communicate immediately with the Isotope Usage Panel, so that appropriate arrangements can be made.
It should be emphasized that the final responsibility for the proper usage of isotopes on Scripps 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 appropriate Radiation Safety Officers.