Results* from April citizen science monitoring are now available from 8 of 11 (above: bold italics) of the current InFORM sampling locations. Additionally, two samples from May are available from Ucluelet and Port Renfrew. The Ucluelet sample was collected by the Ucluelet Aquarium for our partner organization, Our Radioactive Ocean, on May 7th and did contain trace amounts (0.5 Bq m-3) of the Fukushima fingerprint, 134Cs, with it’s short ~2 year half life. The total level of activity from this sample is roughly half the activity of the February sample, which was the last time 134Cs was detected on the BC coast.
No Fukushima-derived radiation was present in the other samples collected on the coast just prior to, or just after, the Ucluelet sample. Based on satellite observations of sea surface temperature, the sample collected in Tofino, on April 30th (above left), appears to have been just prior to a period of onshore flow. This flow is represented by warmer temperatures (right, increased green) on 7 May, the date of the Ucluelet collection, and may have contributed to the positive Ucluelet result. The next sample, from Port Renfrew on May 23rd, may have been absent of 134Cs because of its location in the Strait of Juan de Fuca, within the Salish Sea esturary. As represented by the cool colors above, the surface waters of the Strait are much colder (and fresher, salinity not shown) than the coastal ocean. These conditions are consistent with typical estuarine circulation where fresh water flows out to the ocean at the surface and salty water flows inland at depth. Since the surface water at this location is more strongly influenced by estuarine waters than the open ocean, this may explain the lack of 134Cs in this sample. Further analysis is necessary to confirm this hypothesis.
As in February and March, this period of InFORM monitoring highlights the dynamic nature of our coastal ocean. Based on the broad stretch of warm oceanic water pushed up against Vancouver Island in May, we expect we will see more samples with measurable Fukushima radiation present as results become available for other outer coast samples.
All coastal samples continue to have measureable levels of 137Cs (half-life ~30 years), that is present because of atmospheric nuclear weapons testing that happened in the 1950s and 1960s and the 1986 Chernobyl nuclear disaster.
*Note: Results are preliminary and may be slightly adjusted pending results from further chemical analysis.