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

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

Tuborg Lake is at 81°N, 76°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 ±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 ±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

Strontium Isotope Composition and Trace Element Concentrations in Lake Huron and its Principal Tributaries

(print) ix, 109 p. : ill., maps ; 28 cm.Concentrations of the major cations: Na, K, Ca, Mg and Sr were determined for 64 samples of surface water from Lake Huron and for 17 of its major tributary rivers. For addition, isotopic compositions of strontium were measured for 30 samples of lake water and for 13 of the tributary rivers. Concentrations of dissolved iron and total phosphorus were determined for a small suite of lake and river water. The data document important differences in the chemical composition of water discharged into Lake Huron by Lake Superior, Lake Michigan and tributary rivers. These differences are related to differences in the chemical and mineralogical composition of the bedrock underlying the Great Lakes drainage basin. The strontium contributed to Lake Huron by water draining the Canadian Shield along its northern shore is enriched in radiogenic Sr87. The average Sr87/ Sr86 ratio is 0. 718. The rivers draining sedimentary rocks of Michigan and southwestern Ontario contribute strontium whose isotope composition is similar to that in the modern oceans and has a Sr87/Sr86 ratio of 0.710. A geochemical model is presented which attempts to represent the chemical composition of water in Lake Huron as a mixture of the different types of water discharged by different sources.Abstract -- Statement of the Significance and Applicability of the Results -- Table of Contents -- List of Tables -- List of Figures -- Acknowledgments -- Introduction -- Collection of Water Samples -- Analytical Methods -- Precision and Accuracy -- Presentation and Discussion of the Results -- Formulation of a Model for the Chemical Composition of Lake Huron -- The Isotope Composition of Strontium in the Great Lakes -- Summary and Conclusions -- References -- Geochemical Aspects of the Scioto and Olentangy Rivers, Columbus, Ohi

Sulfur- and strontium-isotopic geochemistry of celestite, barite and gypsum from the Mesozoic basins of northeastern Mexico

The Mesozoic sedimentary basin of northern Mexico contains large limestone-hosted stratiform "mantos" of celestite and barite that appear to have formed by carbonate replacement. We have measured the isotopic compositions of sulfur and strontium in these mantos in order to determine whether they formed by diagenetic processes and, if so, what fraction of the diagenetically released Sr is fixed in celestite deposits. S- and Sr-isotopic analyses of gypsum from layers in the limestone confirm its Cretaceous sedimentary origin. Isotopic compositions of most celestite and barite differ from values observed for the gypsum. Division of the deposits into two geologically and geochemically distinct groups shows that there is a general positive correlation between [delta] 34S and 87Sr/86Sr compositions of celestite and barite in the two systems, with celestite containing lighter S and less radiogenic Sr in both groups of deposits. Less radiogenic Sr in the celestite probably came from nearby Cretaceous limestones. More radiogenic Sr, which is found largely in the barite, probably came from basement-derived arkoses in the Cretaceous basin. Sulfur was derived from evaporites in one deposit group and from some other lighter source, perhaps coal or petroleum, in the other. These isotopic constraints, considered in the light of available solubility data, require that at least two distinct solutions existed and mixed locally during formation of the celestite and barite mantos. No more than 10% of the diagenetically-released Sr is concentrated in the celestite deposits.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/23386/1/0000331.pd

Studies in the Geochronology and Geochemistry of the Transantarctic Mountains

This is the third annual progress report submitted by Institute of Polar Studies researchers to the National Science Foundation (Grant No. GA-898X) on the geochronology and geochemistry of rocks from the Transantarctic Mountains, Antarctica. The results reported in this report are preliminary in nature.National Science Foundation Grant GA-898

The Preparation and Certification of School Librarians: Using Causal Educational Research About Teacher Characteristics to Probe Facets of Effectiveness

How do we define a high-quality school librarian? Decades of educational researchers have attempted to link teacher characteristics—such as how teachers are prepared, which credentials they carry, and years of experience—to student outcomes. These researchers have contended that individual educator attributes may have a direct effect on what and how much their students learn. School librarians are also teachers who have direct student contact, and although numerous studies have indicated that school librarian preparation, licensure, and other background characteristics are promising areas for further direct exploration, researchers have yet to examine if, how, and why school librarians’ certification or preparation positively impacts students’ learning outcomes. The purpose of this paper is to compare findings from causal educational research to findings from descriptive school librarianship research to discern possible areas of causal alignment that warrant further investigation. In this study, we present a subset of a larger mixed research synthesis of causal educational research related to student achievement, contextualized with existing school librarianship research, to draw relationships between classroom teacher and school librarian preparation and characteristics and to shape researchable conjectures about school librarians’ effects on learner outcomes

Strontium isotope geochemistry of late cretaceous granodiorites, Jamaica and Haiti, greater Antilles

Initial 87Sr/86Sr ratios have been determined for a representative suite of Upper Cretaceous granodiorites and associated rocks from the Above Rocks composite stock in central Jamaica and the Terre-Neuve pluton in northwestern Haiti. The average initial 87Sr/86Sr ratio for severn samples of the Terre-Neuve intrusion is 0.7036, with a range of 0.7026-0.7047. For two samples of the Above Rocks the initial ratios are 0.7033 and 0.7034. A third sample from this intrusive has an initial ratio of 0.7084, which is tenatively attributed to contamination. The initial 87Sr/86Sr ratios indicate that neither ancient sialic crust nor sediments carried down a Benioff zone can be the primary source of the granodioritic magma. K/Rb ratios for these rocks range from 178 to 247, which are much lower than the average values (>=1000) for tholeiitic basalts. It is concluded that the magmas originated primarily by melting of downthrust oceanic crust or adjacent mantle material.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/23675/1/0000644.pd

Association of CREBRF variants with obesity and diabetes in Pacific Islanders from Guam and Saipan

Aims hypothesis Variants in CREBRF (rs12513649 and rs373863828) have been strongly associated with increased BMI and decreased risk of type 2 diabetes in Polynesian populations; the A allele at rs373863828 is common in Polynesians but rare in most other global populations. The aim of the present study was to assess the association of CREBRF variants with obesity and diabetes in Pacific Islander (largely Marianas and Micronesian) populations from Guam and Saipan. Methods CREBRF rs12513649 and rs373863828 were genotyped in 2022 participants in a community-based cross-sectional study designed to identify determinants of diabetes and end-stage renal disease (ESRD). Associations were analysed with adjustment for age, sex, ESRD and the first four genetic principal components from a genome-wide association study (to account for population stratification); a genomic control procedure was used to account for residual stratification. Results The G allele at rs12513649 had an overall frequency of 7.7%, which varied from 2.2% to 20.7% across different Marianas and Micronesian populations; overall frequency of the A allele at rs373863828 was 4.2% (range: 1.1–5.4%). The G allele at rs12513649 was associated with higher BMI (β=1.55 kg/m2 per copy; p=0.0026) as was the A allele at rs373863828 (β=1.48 kg/m2, p=0.033). The same alleles were associated with lower risk of diabetes (OR per copy: 0.63 [p=0.0063] and 0.49 [p=0.0022], respectively). Meta-analyses combining the current results with previous results in Polynesians showed a strong association between the A allele at rs373863828 and BMI (β=1.38 kg/m2;p=2.5×l0−29) and diabetes (OR=0.65, p=1.5×l0−13). Conclusions interpretation These results confirm the associations of CREBRF variants with higher BMI and lower risk of diabetes and, importantly, they suggest that these variants contribute to the risk of obesity and diabetes in Oceanic populations

Mycobacterium tuberculosis Transmission from Human to Canine

A 71-year-old woman from Tennessee, USA with a 3-week history of a productive, nonbloody cough was evaluated. Chest radiograph showed infiltrates and atelectasis in the upper lobe of the right lung. A tuberculosis (TB) skin test resulted in a 14-mm area of induration. Sputum stained positive for acid-fast bacilli (AFB) and was positive for Mycobacterium tuberculosis by DNA probe and culture. Treatment was initiated with isoniazid, rifampicin, and pyrazinamide. After 14 days of daily, directly observed therapy, the patient complained of nausea, vomiting and diarrhoea. Treatment adjustments were made, and therapy was completed 11 months later with complete recovery. Six months after the patient\u27s TB diagnosis, she took her three and a half-year-old male Yorkshire Terrier to a veterinary clinic with cough, weight loss, and vomiting of several months\u27 duration. Initial sputum sample was negative on AFB staining. Eight days after discharge from a referral veterinary teaching hospital with a presumptive diagnosis of TB, the dog was euthanized due to urethral obstruction. Liver and tracheobronchial lymph node specimens collected at necropsy were positive for M. tuberculosis complex by polymerase chain reaction. The M. tuberculosis isolates from the dog and its owner had an indistinguishable 10-band pattern by IS6110-based restriction fragment length polymorphism genotyping