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Paleolimnological Analysis Of The History Of Metals Contamination In The Great Salt Lake, Utah, Wayne A. Wurtsbaugh, Katrina Moser, Peter R. Leavitt
Paleolimnological Analysis Of The History Of Metals Contamination In The Great Salt Lake, Utah, Wayne A. Wurtsbaugh, Katrina Moser, Peter R. Leavitt
Wayne A. Wurtsbaugh
Three sediment cores from the Great Salt Lake were analyzed to determine the magnitude and timing for the deposition of 21 metal contaminants. In the main lake (Gilbert Bay) concentrations of copper, lead, zinc, cadmium, silver, molybdenum, tin, mercury and others began increasing in the sediments in the late 1800s or early 1900s and peaked in the 1950s. These increases were coincident with increases in mining and smelting activities for these metals in Utah. Contamination indices in the 1950s were 20-60 fold above background concentrations for silver, copper, lead and molybdenum, and <15-fold for most other metals. Since the 1950s, concentrations of most metals in the sediments have decreased 2-5 fold coincident with decreases in mining and improved smelting technologies. Nevertheless concentrations for many metals in surficial sediments are still above acceptable criteria established for freshwater ecosystems. In contrast to most metals, concentrations of selenium and arsenic were stable or increasing slightly in the Gilbert Bay sediments. In a coring site located in Farmington Bay near an EPA Superfund Site discharge canal, concentrations of metals were high and showed no indication of decreasing in more recent sediments. Surficial sediments from additional sites in the Great Salt Lake indicated that metals were more concentrated towards the southern end of the lake where the primary sources of contamination were located.
Proton‐Donor Properties Of Water And Ammonia In Van Der Waals Complexes. Be–H2o And Be–Nh3, G. Chalasinski, M. M. Szczesniak, Steve Scheiner
Proton‐Donor Properties Of Water And Ammonia In Van Der Waals Complexes. Be–H2o And Be–Nh3, G. Chalasinski, M. M. Szczesniak, Steve Scheiner
Steve Scheiner
The potential energy surfaces (PES) of Be–H2O and Be–NH3 are studied with particular attention to characterization of proton‐donor properties of water and ammonia. Calculations were performed by means of both supermolecular and intermolecular Møller Plesset perturbation theory. The Be–H2O PES reveals two van der Waals minima: the C2v minimum (De=176 cm−1, Re=6.5 bohr), and the H‐bonded minimum (De=161 cm−1, Re=7.5 bohr), separated by a barrier of 43 cm−1 at the T‐shaped configuration. The Be–NH3 PES reveals only …
Proton–Donor Properties Of Water And Ammonia In Van Der Waals Complexes With Rare‐Gas Atoms. Kr–H2o And Kr–Nh3, G. Chalasinski, M. M. Szczesniak, Steve Scheiner
Proton–Donor Properties Of Water And Ammonia In Van Der Waals Complexes With Rare‐Gas Atoms. Kr–H2o And Kr–Nh3, G. Chalasinski, M. M. Szczesniak, Steve Scheiner
Steve Scheiner
The perturbation theory of intermolecular forces in conjunction with the supermolecular Møller–Plesset perturbation theory is applied to the analysis of the potential‐energy surfaces of Kr–H2O and Kr–NH3 complexes. The valleylike minimum region on the potential‐energy surface of Kr–H2O ranges from the coplanar geometry with the C2 axis of H2O nearly perpendicular to the O–Kr axis (T structure) to the H‐bond structure in which Kr faces the H atom of H2O. Compared to the previously studied Ar–H2O [J. Chem. Phys. 94, 2807 (1991)] the minimum has more …