Connection of a 90Sr Groundwater Plume with Local Tree Swallows
Connection of a 90Sr Groundwater Plume with Local Tree Swallows
Previously Published Material: Some of this material was presented at the 2013 GSA meeting in Denver, emphasizing the methods used to quantify mass flux of Sr-90 into the littoral zone. This submission, however is an update. It will feature the findings of 2013 and 2014 and the linkage between tree swallows and the local groundwater system.
Abstract ID#: 35453
English Abstract:
We traced the movement of a strontium-90 (90Sr) plume from source to tree swallows. The source was leakage from a nuclear fuel storage pool. Swallow nest boxes were placed so parent birds would feed their nestlings with insects that emerged from sediments in the 90Sr groundwater discharge zone and from sediments in background control sites. Nest boxes were observed regularly during nest building, egg laying, brooding, hatching and fledging. When nestlings were 12-days-old, one nestling from each of 12 nests at sites labelled with 90Sr (as a result of groundwater discharge) and one nestling from each of two nests at background sites were taken under a Federal Permit and an approved animal care protocol. Gross beta concentrations in the bone and body of nestlings were consistent with the proximity of the nest boxes to the 90Sr-groundwater discharge area. Lower leg samples from nestlings from the 90Sr-labelled site had 7 to 9 times more gross beta radiation than whole bodies, consistent with the expectation that the excess radioactivity was due to 90Sr concentrated in bone. Gross beta of the lower legs vs. bodies for all 14 samples were highly correlated (r2 = 0.94). Although the paucity of control site nestlings prevented statistical comparisons, a preliminary conclusion is that there was no reproductive impairment of swallows at 90Sr-labelled sites. Conservative estimates of internal doses, due to 5 Bq g-1of 90Sr/90Y in maximally burdened nestlings, were 8 uGy hr-1as compared with 40 uGy hr-1, which is an internationally recognized benchmark for protection of riparian and terrestrial animals. This study marks an initial effort to perform a biota- dose assessment of 90Sr groundwater plumes where these plumes constitute a nutritional connection between the groundwater system and the local ecology. Future work will use tree swallows to assess the potential for offsite transfer of 90Sr in edible waterfowl and to quantify radioecological effects, if any.
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