Occurrence and Cesium-137 and Other Radionuclides in the Surface Layers of Soil in Ohio and Antarctica

Author Institution: Department of Geological Sciences, The Ohio State UniversityThe testing of nuclear weapons in the atmosphere in the 1960s and the accidental explosion of a nuclear reactor in 1986 near Chernobyl, Ukraine, caused large amounts of fission-product radionuclides to be deposited over most of the surface of the Earth. The present study was undertaken in order to compare the decay rates of l37Cs in the surface layer of soil in central Ohio at 40°N and in Antarctica at 77°S latitude. The measurements were made by means of gamma-ray spectrometry on 10 gram samples of bulk soil collected from the surface. The results indicate that the decay rate of l37Cs in the Ohio soil sample is (2.2 ± 0.8) x 10 ' pico Curies/g, whereas the rate of decay of this radionuclide in the antarctic soils is below the limit of detection (<1 x 102 pCi/g). In addition, roots in the Ohio soil do not contain detectable 137Cs, confirming that this radionuclide is not absorbed by plant roots because of its strong absorption on the surfaces of clay minerals. Soils in Ohio and Antarctica do contain long-lived unstable 40K, as well as short-lived unstable daughters of 238U (214Pb and 214Bi) and of 232Th (228Ac, 212Pb, 208Tl, and 228Th). The apparent absence of 137Cs in the surface layer of antarctic soils is most likely the result of nondeposition of radioactive fallout at the extreme southern latitudes of Antarctica

Seasonal Variation of the Solute Content and the Sr87/Sr86 Ratio of the Olentangy and Scioto Rivers at Columbus, Ohio

Author Institution: Department of Geology and Water Resources Center, The Ohio State University, Columbus, Ohio 43210The concentrations of sodium, potassium, calcium, and strontium in water samples collected from the Olentangy and Scioto Rivers at Columbus, Ohio, during 1966, have been determined. The water samples were collected at weekly intervals throughout the year and were combined into four-week composites. The average concentrations, weighted according to discharge, and the ranges of variation for each element in the Olentangy River (in units of Mg/ml) were: Na = 22.3 (16.6 to 38.5), K = 3.3 (2.2 to 4.9), Ca = 72.4 (54.4-101.5), Sr=0.923 (0.604 to 1.73). In the Scioto River the concentrations of these elements were: Na = 12.2 (5.8 to 20.3), K = 3.6 (2.2 to 5.0), Ca = 78.8 (53.2 to 96.2), Sr = 1.91 (0.954 to 2.79). In both rivers the concentrations of sodium and strontium decreased linearly with increasing discharge, whereas the concentrations of potassium and calcium did not. The concentration of potassium increased steadily during the summer and reached a peak in the fall. The Sr87/Sr86 ratio of the Olentangy River decreased with increasing discharge from 0.7116 to 0.7088 while that of the Scioto River appeared to be constant at 0.7093 =±= 0.0003 within the precision of the measurement

Possible Contamination of the Sandusky River by Wastewater Discharge by Bucyrus, Ohio

Author Institution: Department of Geological Sciences, The Ohio State UniversityThe objective of this study was to determine changes in the chemical composition of water that result from its use by the town of Bucyrus in Crawford County, OH, and to document the effect of the discharge of wastewater on the quality of water in the Sandusky River. The results indicate that the wastewater is enriched in the major elements (Na, K, Mg, Ca, and Sr) compared to tap water in the town of Bucyrus. However, the treated wastewater does not significantly alter the chemical composition of water in the Sandusky River represented by a ten-year average from 1984 to 1994. The concentrations of Mo in raw water and in the wastewater are nearly identical, which means it cannot have an anthropogenic source. The wastewater does not contain P because this element is effectively removed as required by the Great Lakes Water Quality Agreement

Feldspar-Provenance Dates in a Stratigraphic Section of Till in Gahanna, Ohio

Author Institution: Department of Geology and Mineralogy and The Institute of Polar Studies, The Ohio State UniversityThe internal layering and provenance of feldspar in 3 tills and in one outwash deposit at Gahanna, Ohio, were studied by determining pebble lithologies and Rb-Sr dates of feldspar. Variations in lithology of pebbles and in the Rb-Sr ratios of feldspar in the 125—250 micrometer fractions reveal discontinuities which divide the upper 2 tills into 2 subunits each. Each of the lower subunits appears to be more homogeneous than the upper ones based on comparisons of standard deviations. This suggests the lower subunits may be basal or lodgement till and the upper subunits may be ablation till. Feldspar-provenance dates in till of the mid western United States are expressions of the proportion of mixing of feldspar grains originating from the Superior (2.7 b. y.) and Grenville (1.07 b. y.) structural provinces of the Canadian Precambrian Shield. The Rb-Sr dates of feldspar in the layers of till and outwash of the Gahanna section are so variable that average dates cannot be used to distinguish among them. The lack of systematic stratigraphic variation of provenance dates indicates the feldspars are heterogeneous mixtures of the two Precambrian components. Approximately 90% of the dates have values between 1.0 and 1.5 b.y., which demonstrates the dominance of feldspar derived from the Grenville Province. Four samples whose dates are less than 1.0 b. y. contain younger feldspar presumably derived from sandstone of late Paleozoic age

The Isotopic Composition and Concentration of Strontium of the Brine From Tuborg Lake, Ellesmere Island

Tuborg Lake is at 81&deg;N, 76&deg;W at the head of Antoinette Bay in northern Ellesmere Island, Northwest Territories. It trends in an east-west direction and is separated from the fjord by a glacier at its western margin. The lake is 20 km long and about 3 km at its widest. An active glacier at the eastern end calves occasional small icebergs into the lake. In June 1963, the level of water in the lake was 10 to 12 m above sea level. The lake is markedly density-stratified; the salinity is less than 0.5 per mil depth of more than 46 m below its surface. The salinity rapidly increases below this depth, and at a depth of 57 m it is 25.594 per mil. Hattersley-Smith and Serson attribute the saline water at the bottom of the lake to sea water trapped by the advance of the glacier across the fjord. The depth of the halocline at 50 to 55 m (thus 40 to 45 m below sea level) and the fact that the present level of the lake is about 10 m above sea level both suggest a complex history of the lake. Recently, the isotopic composition of strontium, conveniently expressed as the 87Sr/86Sr ratio, has been used to indicate the source of dissolved salts .... The 87Sr/86Sr ratio of surface water depends on the Rb/Sr ratios and ages of the rocks exposed in the drainage basin. ... The isotopic composition of strontium in sea water is constant (87Sr/86Sr = 0.7093) and can therefore be useful in identifying marine strontium. The isotopic composition of strontium was determined on a sample of the brine from Lake Tuborg. This sample was collected 22 June 1967 at a depth of 90 m below the surface of the lake. At the sampling site the maximum depth of the lake was 130 m and the depth of the halocline was 60 m; salinity of the sample is 26 per mil. ... The 87Sr/86Sr ratio for the brine at 90 m depth of Lake Tuborg has a value of 0.7096 &plusmn;0.0005 (1 sigma), which is in satisfactory agreement with the accepted value for modern sea water. This suggests that the brine at the bottom of the lake could be sea water. However, this is not conclusive, because the dominant bedrock in the region consists mainly of marine carbonates of Early to Middle Cambrian age. The 87Sr/86Sr ratio of these rocks probably does not differ greatly from this value. We analyzed one specimen of limestone of Middle Cambrian age from the Nelson Formation of the Neptune Range, Pensacola Mountains, Antarctica, and obtained an 87Sr/86Sr ratio of 0.7093. The concentration of strontium, determined by isotope dilution using a spike enriched in 86Sr, was 6.239 ppm and is somewhat less than that of normal sea water, which has a strontium content of approximately 8 ppm. Using the established relationship between salinity and chlorinity in sea water and a salinity of 26 per mil, we find a chlorinity of 14.4 per mil for the brine sample. Accordingly, the Sr/Cl ratio of this brine is 0.43. Riley and Tongudai obtained an average value of 0.42 &plusmn;0.02 for this ratio for a large suite of sea water samples. The Sr/Cl ratio of the brine from Lake Tuborg is similar to this value, which also suggests that the brine could be sea water

The Isotope Composition of Strontium and Cation Concentrations of Lake Vanda and Lake Bonney in Southern Victoria Land, Antarctica

"RF 2340" and "RF 2411"This report is based on a dissertation submitted by Lois M. Jones to the Graduate School of The Ohio State University.Second Annual Progress Report Grants GA-1713, GA-898X, submitted to the National Science FoundationThe ice-free valleys of southern Victoria Land are located in the Transantarctic Mountains west of Ross Island, Antarctica. In these valleys, the average annual temperature is well below the freezing point of water and precipitation is extremely low. Nevertheless, lakes are present and soils have begun to form since deglaciation. These lakes and soils are characterized by high concentrations of salts. The salinity of some lakes, such as Lake Vanda and Don Juan Pond in Wright Valley and Lake Bonney in Taylor Valley, is several times greater than that of sea water. In addition, salts occur as surface efflorescences and as lenses and cement within the soil. The origin of the salts in the lakes and soils of the ice- free valleys is controversial. Possible sources that have been suggested include: (l) trapped sea water; (2) wind-transported marine salts; (3) volcanic activity and associated hot springs; and (4) chemical weathering of local soil and bedrock. Previous attempts to explain the origin of the salts have resulted in conflicting conclusions because the parameters which were used (chemical composition, isotope composition of the water) have been modified by chemical or physical processes occurring in the lakes. In order to determine the origins of the salts, a new parameter is needed that can unambiguously identify a specific source for the salts. The isotopic composition of strontium in the salts meets the necessary requirements because: (1) the isotopic composition of strontium of each of the possible sources is distinctive and differs significantly from that of the other sources, and (2) the isotopes of strontium are not measurably fractionated in natural processes such as are occurring in the ice- free valleys. The objective of this study was to ascertain the usefulness of strontium isotopes as natural tracers, and to identify thereby the source(s) of the salts in the lakes and soils of the ice-free valleys in Antarctica. Lakes Vanda and Bonney were studied in detail because they are the largest and most unusual of the Antarctica lakes. Both lakes are perennially ice-covered and are meromictic. At depth the water is highly saline and has surprisingly high temperatures. Lake Vanda has a maximum density of 1.10 g/ml at a depth of 67 m, and a maximum recorded temperature of +28°C at the bottom of the lake. Lake Bonney has a maximum density of 1.20 g/ml at a depth of 32 m, and reaches a temperature of +8°C at about the middle of the depth profile. In order to determine the origin of the salts in the two lakes, measurements were made of the isotopic composition of strontium in water samples collected at different depths from the surface to the bottom of the lakes. The results of these analyses were then compared to isotopic compositions of strontium in sea water, basalts of the McMurdo volcanic province, and the strontium in water-soluble salts from the soils in Wright and Taylor Valleys. From these comparisons the principal sources of the strontium in the two lakes can be clearly identified. In addition to measurements of the isotopic composition of strontium in the lakes, chemical analyses of the brines have been made to provide information that can be used with the isotopic studies to develop a model for the geochemical evolution of the lakes. The combination of isotopic and chemical analyses of the brines in Lakes Vanda and Bonney permits the formulation of a better model than has been possible before.National Science Foundation Grants GA-713 and GA-898