Strontium 90 in maize field, cattail marsh and oak-wood ecosystems.
In late 1959 the above-ground parts of cattail and maize ecosystems contained 4.4 and 2.8 µc/ha Sr90 respectively, much less than the annual fallout. These amounts were similar to those found in the vegetation of Minnesota pastures. In pastures the quantity of Sr90 in the vegetation was only a few % of that in the root mat and top 5 cm of soil, so probably much of the Sr90 in the maize field and cattail marsh was also in the soil and not in the living plants. The trees of the oakwood contained much more Sr90 (48.2 µc/ha) than the living plants of other ecosystems. The total Sr90 (136 µc/ha) in the organic matter in the oakwood was in the range reported for the total Sr90 in the vegetation, root mat and surface soil of pastures under roughly comparable rainfalls in Minnesota and Britain. Since the accumulation of Sr90 in terrestrial ecosystems is fairly uniform for comparable localities much of the Sr90 in the woodland was likely to be in the organic matter and relatively little in the mineral soil. The oakwood differed greatly from herbaceous ecosystems in the distribution and anticipated rate of movement of Sr90. Oak leaves contained only 3.33 µc/ha Sr90, much less than the more persistent living branches (20.03), trunks (11.08), dead branches (13.76) and litter (88.23 µc).