Iron in Surface and Subsurface Waters, Grizzly Bar, Southeastern Alaska

Completion Report for Project A-019-ALAS to the Office of Water Resources Research, Department of the Interior, August 1972Atomic absorption spectrophotometric measurements for total iron were made on 69 samples of water from 8 different environments in an outwash fan built by meltwater streams from the retreating Norris Glacier on granodiorite bedrock. Norris Glacier ice contained no iron (3 samples), a subglacial stream contained 5.5 ppm Fe (1 sample), and a meltwater lake fronting Norris Glacier contained 0.7 ppm Fe (3 samples). Iron content of ground water from outwash ranged between 0.0 and 17.0 ppm (6 samples); surface streams fed by emergent ground water on the fan periphery contained 0.0 to 0.2 ppm Fe (13 samples). Taku Inlet waters contained 6.4 ppm Fe (3 samples). Subsurface water from an intertidal mud flat contained between 0.0 and 27.0, X 5.9, ppm Fe (31 samples). Surface and subsurface water from a bog and associated stream contained 1 ppm Fe (12 samples). Little exchangeable Fe was found. In situ measurements in water for Eh showed large positive values (+0.30 to +0.50 volts) and pH was slightly alkaline. The single most important source of iron was vermiculitized biotite. Iron was transported in water in the particulate state, except in outwash ground water where particulate Fe+3 was reduced to dissolved Fe+2. Iron deposits of Fe(OH)3 were found near the top of the outwash water table.The work upon which this report is based was supported in part by the funds (Proj. A·019-ALAS) provided by the United States Department of the Interior, Office of Water Resources Research, as authorized under the Water Resources Act of 1964, as amended

Sedimentological And Geochemical Aspects Of Sediment And Water From Ten Alaskan Valley Glaciers

Thesis (Ph.D.) University of Alaska Fairbanks, 197

Sediments of the Norris Glacier outwash area, upper Taku Inlet, southeastern Alaska

Thesis (M.S.) University of Alaska Fairbanks, 1967An 8-square mile outwash fan, composed of gravelly sediment, extends from the terminus of Norris Glacier to the waters of upper Taku Inlet, Southeastern Alaska. Thirty-seven surface sediment samples from the tidal portion of the fan form the bulk of this study. The tidal flat is largely composed of very poorly sorted muddy sediment and relatively well sorted sand which, for the most part, overlie outwash gravel. Mixing of various modal size classes has produced a complex sediment distribution pattern as well as a complicated size-sorting relationship. The sand-size fraction of the sediments consists of feldspar, quartz, rock fragments, amphiboles, pyroxenes, micas and opaques; the clay-size fraction consists of micas, chlorite, montmorillonite, feldspar and amphibole. The sediments are the product of glacial abrasion in the Juneau Ice Field area. The sand and mud are derived largely from Norris and Taku Glacier detritus; their nature indicates valley glacier detritus may be fairly rapidly sorted when subjected to hydraulic action. Absence of quartz and presence of feldspar in the clay-size fraction may indicate the physical properties of these minerals control the size to which they can be reduced by valley-glacier abrasion

Community preceptors' views of a required third-year family medicine clerkship

BACKGROUND: Previous studies documented the importance of family medicine clerkships to medical student education and to the potential costs of precepting students borne by community physicians. But what are the physicians' views of their experience, their perceived needs for teaching, and sources of satisfaction from the preceptor role? OBJECTIVES: To explore preceptors' views of a required, third-year family medicine clerkship, focusing on satisfaction with the teaching experience, effect of having students in the practice, and concerns about continuing as a preceptor. METHODS: Preceptors from 38 private practices were asked to participate in a 15-minute telephone survey, using a semistructured interview format. RESULTS: Thirty-five physicians (92%) agreed to participate and 33 of the 35 primary preceptors were interviewed. Of those interviewed, 29 (88%) indicated a positive teaching experience, and 31 (94%) desired to continue precepting. Intangible rewards (eg, love of teaching or "giving back" to the specialty of family medicine) far out-weighed tangible rewards (eg, dinners or letters of appreciation) with regard to their desire to precept. Continued satisfaction with precepting seemed to be affected by loss of revenue to the practice, longer work hours, ability to effectively manage time and patient load, and need for additional educational resources and equipment. CONCLUSIONS: Intrinsic rewards seem to be a key factor in the physicians' decision to precept. Moreover, to reinforce the preceptor's continued desire to precept, faculty development, provision of educational tools and resources, and remuneration may be necessary. Preceptors should be asked routinely about their needs, and special programs of support should be offered

Predicted facies, sedimentary structures and potential resources of Jurassic petroleum complex in S-E Western Siberia (based on well logging data)

This paper is devoted to the current problem in petroleum geology and geophysics- prediction of facies sediments for further evaluation of productive layers. Applying the acoustic method and the characterizing sedimentary structure for each coastal-marine-delta type was determined. The summary of sedimentary structure characteristics and reservoir properties (porosity and permeability) of typical facies were described. Logging models SP, EL and GR (configuration, curve range) in interpreting geophysical data for each litho-facies were identified. According to geophysical characteristics these sediments can be classified as coastal-marine-delta. Prediction models for potential Jurassic oil-gas bearing complexes (horizon J[1]{1}) in one S-E Western Siberian deposit were conducted. Comparing forecasting to actual testing data of layer J[1]{1} showed that the prediction is about 85%

Atmospheric hydrogen sulfide over the equatorial Pacific (SAGA 3)

Atmospheric H2S concentrations were measured over the equatorial Pacific on leg 1 of the third Soviet-American Gases and Aerosols (SAGA 3) cruise during February and March 1990. Five N-S transects were made across the equator between Hawaii and American Samoa. The concentrations ranged from below the detection limit of 0.4 ± 0.5 (1 σ) to 14.4 ppt with an average value of 3.6 ± 2.3 ppt (1σ, n= 72). The highest concentrations were found on the easternmost two transects just south of the equator. The average concentration of 3.6 ppt observed on this cruise is the lowest reported value for background atmospheric H2S over the tropical oceans. A lack of correlation between 222Rn and H2S rules out a significant continental source. Model calculations indicate that the oceanic source of H2S in this region is in the range of 9 to 21 × 10−8 mol m−2 d−1. From this flux the concentration of free sulfide (H2S + S= ) in the surface mixed layer of the ocean is estimated to be in the range of 32 to 67 pmol L−1. In the atmosphere the oxidation of H2S produces SO2 at a rate of 2.1 to 4.4 × 10−11 mol m−3 d−1 which is only a small fraction of that estimated from the oxidation of dimethyl sulfide (DMS) in this region. A diurnal cycle was not observed in the H2S data recorded during this cruise

A database solution for the quantitative characterisation and comparison of deep-marine siliciclastic depositional systems

In sedimentological investigations, the ability to conduct comparative analyses between deep-marine depositional systems is hindered by the wide variety in methods of data collection, scales of observation, resolution, classification approaches and terminology. A relational database, the Deep-Marine Architecture Knowledge Store (DMAKS), has been developed to facilitate such analyses, through the integration of deep-marine sedimentological data collated to a common standard. DMAKS hosts data on siliciclastic deep-marine system boundary conditions, and on architectural and facies properties, including spatial, temporal and hierarchical relationships between units at multiple scales. DMAKS has been devised to include original and literature-derived data from studies of the modern sea-floor, and from ancient successions studied in the sub-surface and in outcrop. The database can be used as a research tool in both pure and applied science, allowing the quantitative characterisation of deep-marine systems. The ability to synthesise data from several case studies and to filter outputs on multiple parameters that describe the depositional systems and their controlling factors enables evaluation of the degree to which certain controls affect sedimentary architectures, thereby testing the validity of existing models. In applied contexts, DMAKS aids the selection and application of geological analogues to hydrocarbon reservoirs, and permits the development of predictive models of reservoir characteristics that account for geological uncertainty. To demonstrate the breadth of research applications, example outputs are presented on: (i) the characterisation of channel geometries, (ii) the hierarchical organisation of channelised and terminal deposits, (iii) temporal trends in the deposition of terminal lobes, (iv) scaling relationships between adjacent channel and levee architectural elements, (v) quantification of the likely occurrence of elements of different types as a function of the lateral distance away from an element of known type, (vi) proportions and transition statistics of facies in elements and beds, (vii) variability in net-to-gross ratios among element types

Solid-phase arsenic speciation in aquifer sediments: A micro-X-ray absorption spectroscopy approach for quantifying trace-level speciation

Arsenic (As) is a geogenic contaminant affecting groundwater in geologically diverse systems globally. Arsenic release from aquifer sediments to groundwater is favored when biogeochemical conditions, especially oxidation-reduction (redox) potential, in aquifers fluctuate. The specific objective of this research is to identify the solid-phase sources and geochemical mechanisms of release of As in aquifers of the Des Moines Lobe glacial advance. The overarching concept is that conditions present at the aquifer-aquitard interfaces promote a suite of geochemical reactions leading to mineral alteration and release of As to groundwater. A microprobe X-ray absorption spectroscopy (μXAS) approach is developed and applied to rotosonic drill core samples to identify the solid-phase speciation of As in aquifer, aquitard, and aquifer-aquitard interface sediments. This approach addresses the low solid-phase As concentrations, as well as the fine-scale physical and chemical heterogeneity of the sediments. The spectroscopy data are analyzed using novel cosine-distance and correlation-distance hierarchical clustering for Fe 1s and As 1s μXAS datasets. The solid-phase Fe and As speciation is then interpreted using sediment and well-water chemical data to propose solid-phase As reservoirs and release mechanisms. The results confirm that in two of the three locations studied, the glacial sediment forming the aquitard is the source of As to the aquifer sediments. The results are consistent with three different As release mechanisms: (1) desorption from Fe (oxyhydr)oxides, (2) reductive dissolution of Fe (oxyhydr)oxides, and (3) oxidative dissolution of Fe sulfides. The findings confirm that glacial sediments at the interface between aquifer and aquitard are geochemically active zones for As. The diversity of As release mechanisms is consistent with the geographic heterogeneity observed in the distribution of elevated-As wells