Cushing, C. E. et al. “Decrease of Radionuclides in Columbia River Biota Following Closure of Hanford Reactors.” Health Physics 41 (1981): 59-67. (reviewed by Bethany Parkyn)
Summary:
In this article, the authors present a study on the presence of several radionuclides (most notably Cobalt-60 and Zinc-65) in biota in three locations along the Columbia River: White Bluffs, McNary, and Bonneville. They note that although the practice of disposing waste directly into the river has ceased, the N Reactor continues to dump coolant water into a seepage trench periodically. From their startup in 1944, the nine plutonium production reactors released waste directly into the river, and in order to document the rate that the radionuclides left the three ecosystems, the authors sampled several species living in the immediate vicinities.
Results showed that the presence of Cobalt-60 in White Bluffs fluctuated in seston and squawfish, decreased in periphyton and possibly in suckers, and remained constant in caddisfly larvae. In McNary, Cobalt decreased in seston, suckers and periphyton, and actually increased in chironomids. In Bonneville, Cobalt decreased in seston, squawfish and periphyton, and there was no trend in the sucker data.
Zinc had the highest concentration of any of the radionuclides by far. It decreased rapidly in seston and periphyton at White Bluffs, and also decreased at McNary and Bonneville, although over a longer period of time. It also decreased in chironomids, especially those located at McNary. In suckers, the presence of zinc decreased substantially at White Bluffs, and more slowly at the other two locations. Concentrations in squawfish at each location fluctuated and eventually declined.
The authors concluded that the burden placed on biota in the Columbia River ecosystem by radionuclides decreased over a two-year period to essentially unmeasurable levels, and that the slow decline in biota would have occurred more rapidly if the Columbia River was free-flowing.
Critique:
Although the study was published in 1981 and the practice of disposing of waste by dumping it outright into the river has (mostly) been abolished since then, it remains relevant and educational. It highlights several of the actions that can be taken to prevent further harm to the river's ecosystems. Precautions should be taken to prevent the seepage drains from contaminating the river further, and the authors have put forth the hypothesis that free-flowing rivers are better able to expel radionuclides.
The fact that it takes two years to clear the area and mostly end the threat to species is encouraging, in my view, because although a great amount of damage can be inflicted by radionuclides present in the area for two years, I personally expected the time period to be much longer.
Robert D. Clark Honors College, University of Oregon
HC 441: Science Colloquium, Columbia River Ecology
Fall term, 2005
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