Concentrations of iodine-129 in coastal surface sediments around spent nuclear fuel reprocessing plant at Rokkasho, Japan, during and after its test operation

Concentrations of 129I in coastal surface sediment samples from the east coast of Aomori, Japan, 2–65 km away from the wastewater outlet of the nuclear fuel reprocessing plant at Rokkasho, Japan, were measured from 2006 to 2010. No clear effect on 129I/127I atom ratios in marine sediments was observed, although 129I was discharged from the plant, during its test operation using actual spent fuel, mainly between 2006 and 2008. The ratio in sediments collected at a fishing port at the mouth of a brackish lake increased in 2007, showing that the 129I migrated from the lake to the port.

An Investigation into 14C offsets in Modern Mollusk Shell and Flesh from Irish Coasts shows no Significant differences in areas of Carbonate Geology

ABSTRACTOur ability to reliably use radiocarbon (14C) dates of mollusk shells to estimate calendar ages may depend on the feeding preference and habitat of a particular species and the geology of the region. Gastropods that feed by scraping are prone to incorporation of carbon from the substrate into their shells as evidenced by studies comparing the radiocarbon dates of shells and flesh from different species on different substrates (Dye 1994; Hogg et al. 1998). Limpet shells (Patella sp.) are commonly found in prehistoric midden deposits in the British Isles and elsewhere, however these shells have largely been avoided for radiocarbon dating in regions of limestone outcrops. Results from limpets (Patella vulgata) collected alive on limestone and volcanic substrates on the coasts of Ireland indicate that the shells were formed in equilibrium with the seawater, with no significant 14C offsets. Limpets collected from the east coast of Northern Ireland have elevated 14C due to the output of Sellafield nuclear fuel reprocessing plant. In all locations, the flesh was depleted in 14C compared to the shells. The results will have an important consequence for radiocarbon dating of midden deposits as well as the bone of humans and animals who fed on the limpets.