A hypothesis for the geochemical anomaly in the North Creek Watershed /

A regional geochemical reconnaissance by bottom stream sediment sampling, has delineated an area of high metal content in the north central sector of the North Creek Watershed. Development of a geochemical model, relating to the relative chemical concentrations derived from the chemical analyses of bottom sediments, suspended sediments, stream waters and well waters collected from the north central sector, was designed to discover the source of the anomaly. Samples of each type of material were analysed by the A.R.L. Direct Reading Multi-element Emission Spectrograph Q.A. 137 for elements: Na, K, Ca, Sr, Si, As, Pb, Zn, Cd, Ni, Ti, Ag, Mo, Be, Fe, AI, Mn, Cu, Cr, P and Y. Anomalous results led to the discovery of a spring, the waters of which carried high concentrations of Zn, Cd, Pb, As, Ni, Ti, Ag, Sr and Si. In addition, the spring waters had high concentrations of Na, Ca, Mg, 504 , alkalinity, N03' and low concentrations of K, Cl and NH3. Increased specific conductivity (up to 2500 ~mho/cm.) was noted in the spring waters as well as increased calculated total dissolved solids (up to 2047 mg/l) and increased ionic strength (up to 0.06). On the other hand, decreases were noted in water temperature (8°C), pH (pH 7.2) and Eh (+.154 volts). Piezometer nests were installed in the anomalous north central sector of the watershed. In accordance with the slope of the piezometric surface from wells cased down to the till/bedrock interface, groundwater flow is directed from the recharge area (northwest of the anomaly) towards the artesian spring via the highly fractured dolostone aquifer of the Upper Eramosa Member. The bedrock aquifer is confined by the overlying Halton till and the underlying Lower Eramosa Member (Vinemount Shale). The oxidation of sphalerite and galena and the dissolution of gypsum, celestite, calcite, and dolomite within the Eramosa Member, contributed its highly, dissolved constituents to the circulating groundwaters, the age of which is greater than 20 years as determined by tritium dating. Groundwater is assumed to flow along the Vinemount Shale and discharge as an artesian spring where the shale unit becomes discontinuous. The anomaly is located on a topographic low where bedrock is close to the surface. Thermodynamic evaluation of the major ion speciation from the anomalous spring and surface waters, showed gypsum to be supersaturated in these spring waters. Downstream from the spring, the loss of carbon dioxide from the spring waters resulted in the supersaturation with respect to calcite, aragonite, magnesite and dolomite. This corresponded with increases in Eh (+.304 volts) and pH (pH 8.5) in the anomalous surface waters. In conclusion, the interaction of groundwaters within the highly, mineralized carbonate source (Eramosa Member) resulted in the characteristic Ca*Mg*HC03*S04 spring water at the anomalous site, which appeared to be the principle effect upon controlling the anomalous surface water chemistry.

Optical properties of organic superconductor K-(BETS)2FeBr4 /

K-(BETS)2FeBr4 is a quasi-2D charge transfer organic metal with interesting electronic and magnetic properties. It undergoes a transition to an antiferromagnetic (AF) state at ambient pressure at the Neel temperature (T^^) = 2.5 K, as well as to a superconducting (SC) state at 1.1 K [1]. The temperature dependence of the electrical resistivity shows a small decrease at T;v indicating the resistivity drops as a result of the onset of the ordering of Fe'*''" spins. A sharp drop in the resistivity at 1.1 K is due to its superconducting transition. The temperature dependence of the susceptibility indicates an antiferromagnetic spin structure with the easy axis parallel to the a-axis. The specific heat at zero-field shows a large peak at about 2.4 K, which corresponds to the antiferromagnetic transition temperature (Tat) and no anomaly is observed around the superconducting transition temperature (1.1 K) demonstrating that the magnetically ordered state is not destroyed by the appearance of another phase transition (the superconducting transition) in the 7r-electron layers [1], [2]. This work presents an investigation of how the low frequency electromagnetic response is affected by the antiferromagnetic and superconducting states, as well as the onset of strong correlation. The location of the easy axis of three samples was determined and polarized thermal reflectance measurements of these «-(BETS)2FeBr4 samples oriented with their vertical axis along the a- and c axes were then carried out using a *He refrigerator cryostat and a Martin-Puplett type polarizing interferometer at various temperatures (T = 0.5 K, 1.4 K. 1.9 K, 2.8 K) above and below the superconducting state and/or antiferromagnetic state. Comparison of the SC state to the normal state along the o- and c-axes indicates a rising thermal reflectance at low frequencies (below 10 cm"' ) which may be a manifestation of the superconducting energy gap. A dip-Hke feature is detected at low frequencies (below 15 cm"') in the thermal reflectance plots which probe the antiferromagnetic state along the two axes, and may be due to the opening of a gap in the excitation spectrum as a result of the antiferromagnetism. In another set of experiments, thermal reflectance measurements carried out along the a- and c-axes at higher temperatures (10 K-80 K) show that the reflectivity decreases with increasing temperature to 60 K (the coherence temperature) above which it increases again. Comparison of the thermal reflectance plots along the a- and c-axes at higher temperatures reveals an anisotropy between these two axes. The Hagen-Rubens thermal reflectance plots corresponding to an average over the ac-plane were calculated using experimental hterature resistivity values. Comparison of the Hagen-Rubens plots with the experimental thermal reflectance along the a- and c-axes indicates that both exhibit the general trend of a decrease in thermal reflectance with increasing frequency, however the calculated Hagen-Rubens thermal reflectance at different temperatures is much lower than the experimental curves.

Specific heat of UPdâ Siâ

The specific heat of single-crystal U Pd2 Si2 has been studied using both the step heating and continious heating methods for the temperature range 2 to 250 K. Successive phase transitions at Tl = 136I< and T2 = 108I< are reported, which are consistent with current publications. The transition at 40K, which was previously reported, has not been detected. Recent published elastic neutron scattering data, magnetic susceptibility and resistivity results suggest that U Pd2 Si2 may be a heavy fermion compound, however, the electronic specific heat coefficient I (= 18.97 ;~), obtained from the specific heat Cv measurements, is smaller than that of the conventional heavy fermion system. The Debye temperature of U Pd2Si2 is found to be 116.55K. The possibility is discussed that the maximum in CIT in the low-temperature range 2 to 4K corresponds to Schottky anomaly induced by localized magnetic impurities .

Landscape geochemical investigations in the vicinity of a lead deposit near Snertingdal, southern Norway

Landscape geochemical investigations were conducted upon portions of a natural uniform landscape in southern Norway. This consisted of sampling both soil profile samples and spruce tree twigs for the analysis of twelve chemical elements. These elements were cobalt, copper, nickel, lead, zinc, manganese, magnesium, iron, calcium, sodium, potassium and aluminum which were determined by atomic absorption analysis on standardized extraction techniques for both organic and inorganic materials. Two "landscape traverses" were chosen for a comparative study of the effects of varying landscape parameters upon the trace element distribution patterns throughout the landscape traverses. The object of this study was to test this method of investigation and the concept of an ideal uniform landscape under Norwegian conditions. A "control traverse" was established to represent uniform landscape conditions typical of the study area and was used to determine "normal" or average trace element distribution patterns. A "signal traverse" was selected nearby over an area of lead mineralization where the depth to bedrock is very small. The signal traverse provided an area of similar landscape conditions to those of the control traverse with significant differences in the bedrock configuration and composition. This study was also to determine the effect of the bedrock mineralization upon the distribution patterns of the twelve chemical elements within the major components of the two landscape traverses (i.e. soil profiles and tree branches). The lead distribution within the soils of the signal traverse showed localized accumulations of lead within the overburden with maximum values occurring within the organic A horizon of soil profile #10. Above average concentrations of lead were common within the signal traverse, however, the other elements studied were not significantly different from those averages determined throughout the soils of the control traverse. The spruce twig samples did not have corresponding accumulations of lead near the soil lead anomaly. This is attributable to the very localized nature of the lead dispersion pattern within the soils. This approach to the study of the geochemistry of a natural landscape was effective in establishing: a) average or "normal" trace element distribution patterns b) local variations in the landscape morphology and c) the effect of unusually high lead concentrations upon the geochemistry of the landscape (i.e. within the soil profiles and tree branches). This type of study provides the basis for further more intensive studies and serves only as a first approximation of the behaviour of elements within a natural landscape.