Final report for DOE Grant No. DE-FG02-07ER64404 - Field Investigations of Microbially Facilitated Calcite Precipitation for Immobilization of Strontium-90 and Other Trace Metals in the Subsurface

Subsurface radionuclide and metal contaminants throughout the U.S. Department of Energy (DOE) complex pose one of DOEâÃÂÃÂs greatest challenges for long-term stewardship. One promising stabilization mechanism for divalent ions, such as the short-lived radionuclide 90Sr, is co-precipitation in calcite. We have previously found that that nutrient addition can stimulate microbial ureolytic activity that this activity accelerates calcite precipitation and co-precipitation of Sr, and that higher calcite precipitation rates can result in increased Sr partitioning. We have conducted integrated field, laboratory, and computational research to evaluate the relationships between ureolysis and calcite precipitation rates and trace metal partitioning under environmentally relevant conditions, and investigated the coupling between flow/flux manipulations and precipitate distribution. A field experimental campaign conducted at the Integrated Field Research Challenge (IFRC) site located at Rifle, CO was based on a continuous recirculation design; water extracted from a down-gradient well was amended with urea and molasses (a carbon and electron donor) and re-injected into an up-gradient well. The goal of the recirculation design and simultaneous injection of urea and molasses was to uniformly accelerate the hydrolysis of urea and calcite precipitation over the entire inter-wellbore zone. The urea-molasses recirculation phase lasted, with brief interruptions for geophysical surveys, for 12 days followed by long-term monitoring which continued for 13 months. Following the recirculation phase we found persistent increases in urease activity (as determined from 14C labeled laboratory urea hydrolysis rates) in the upper portion of the inter-wellbore zone. We also observed an initial increase (approximately 2 weeks) in urea concentration associated with injection activities followed by decreasing urea concentration and associated increases in ammonium and dissolved inorganic carbon (DIC) following the termination of injection. Based on the loss of urea and the appearance of ammonium, a first order rate constant for urea hydrolysis of 0.18 day-1 rate with an associate Rf for ammonium of 11 were estimated. This rate constant is approximately 6 times higher than estimated for previous field experiments conducted in eastern Idaho. Additionally, DIC carbon isotope ratios were measured for the groundwater. Injected urea had a ÃÂô13C of 40.7ÃÂñ0.4 âÃÂð compared to background groundwater DIC of ÃÂô13C of -16.6ÃÂñ0.2âÃÂð. Observed decreases in groundwater DIC ÃÂô13C of up to -19.8âÃÂð followed temporal trends similar to those observed for ammonium and suggest that both the increase in ammonium and the sift in ÃÂô13C are the result of urea hydrolysis. Although direct observation of calcite precipitation was not possible because of the high pre-existing calcite content in the site sediments, an observed ÃÂô13C decrease for solid carbonates from sediment samples collect following urea injection (compared to pre-injection values) is likely the result of the incorporation of inorganic carbon derived from urea hydrolysis into newly formed solid carbonates

Validated modeling of distributed energy resources at distribution voltages : LDRD project 38672.

A significant barrier to the deployment of distributed energy resources (DER) onto the power grid is uncertainty on the part of utility engineers regarding impacts of DER on their distribution systems. Because of the many possible combinations of DER and local power system characteristics, these impacts can most effectively be studied by computer simulation. The goal of this LDRD project was to develop and experimentally validate models of transient and steady state source behavior for incorporation into utility distribution analysis tools. Development of these models had not been prioritized either by the distributed-generation industry or by the inverter industry. A functioning model of a selected inverter-based DER was developed in collaboration with both the manufacturer and industrial power systems analysts. The model was written in the PSCAD simulation language, a variant of the ElectroMagnetic Transients Program (EMTP), a code that is widely used and accepted by utilities. A stakeholder team was formed and a methodology was established to address the problem. A list of detailed DER/utility interaction concerns was developed and prioritized. The list indicated that the scope of the problem significantly exceeded resources available for this LDRD project. As this work progresses under separate funding, the model will be refined and experimentally validated. It will then be incorporated in utility distribution analysis tools and used to study a variety of DER issues. The key next step will be design of the validation experiments

The domestic and gendered context for retirement

Against a global backdrop of population and workforce ageing, successive UK governments have encouraged people to work longer and delay retirement. Debates focus mainly on factors affecting individuals’ decisions on when and how to retire. We argue that a fuller understanding of retirement can be achieved by recognizing the ways in which individuals’ expectations and behaviours reflect a complicated, dynamic set of interactions between domestic environments and gender roles, often established over a long time period, and more temporally proximate factors. Using a qualitative data set, we explore how the timing, nature and meaning of retirement and retirement planning are played out in specific domestic contexts. We conclude that future research and policies surrounding retirement need to: focus on the household, not the individual; consider retirement as an often messy and disrupted process and not a discrete event; and understand that retirement may mean very different things for women and for men

Supersonic Flight Dynamics Test 2: Trajectory, Atmosphere, and Aerodynamics Reconstruction

The Supersonic Flight Dynamics Test is a full-scale flight test of aerodynamic decelerator technologies developed by the Low Density Supersonic Decelerator technology demonstration project. The purpose of the project is to develop and mature aerodynamic decelerator technologies for landing large-mass payloads on the surface of Mars. The technologies include a Supersonic Inflatable Aerodynamic Decelerator and supersonic parachutes. The first Supersonic Flight Dynamics Test occurred on June 28th, 2014 at the Pacific Missile Range Facility. The purpose of this test was to validate the test architecture for future tests. The flight was a success and, in addition, was able to acquire data on the aerodynamic performance of the supersonic inflatable decelerator. The Supersonic Disksail parachute developed a tear during deployment. The second flight test occurred on June 8th, 2015, and incorporated a Supersonic Ringsail parachute which was redesigned based on data from the first flight. Again, the inflatable decelerator functioned as predicted but the parachute was damaged during deployment. This paper describes the instrumentation, analysis techniques, and acquired flight test data utilized to reconstruct the vehicle trajectory, main motor thrust, atmosphere, and aerodynamics

Climate change in Hong Kong : observations and projections

The Hong Kong Observatory has been making meteorological observations at its headquarters in Tsim Sha Tsui since 1884. Analysis of the extensive past records reveals that the temperature rise in Hong Kong during the past 125 years is in accord with the global rising trend. In last few decades anthropogenic influences, especially urbanization, have contributed significantly to the accelerated rising trend. A similar increasing trend is also observed for rainfall but the trend after 1947 is not statistically significant. Other observations such as increasing cloud amounts, decreasing total global solar radiation and rising sea level are all consistent with the global trend. Studies of past occurrences of extreme temperature and rainfall have recently been carried out. It is observed that cold episodes have become rarer while very hot days and heavy rain events are becoming more frequent. The corresponding return periods of heavy rain and very hot days are decreasing while those of very cold days are increasing. The Observatory also makes use of the data from the latest assessment report of the Intergovernmental Panel on Climate Change and employs statistical downscaling techniques to carry out projections of temperature and precipitation in the 21st century. In gist, the findings are that the rise in temperature will be slightly higher than the global mean in the 21st century. There will also be a significant decrease in the number of cold days and an increase in the number of very hot days and hot nights. The annual rainfall in Hong Kong is also expected to rise by the end of the 21st century, so is the year-to-year variability

Prestige of the bishop in Eusebius' Ecclesiastical history

iv, 250 leaves ; 28 cm.The Ecclesiastical History is the primary historical source of the Christian Church in the pre-Constantinian era. The History narrates the nature and work of Christ, the highlights of the apostolic age and the advancement of the Christian Church in the Roman Empire up to the principate of Constantine. Investigating the Ecclesiastical History using a quantitative method reveals Eusebius' preoccupation with the office of the bishop. There is almost no subject that Eusebius addresses that does not reflect his portrayal of the bishop's influence and universal presence. This thesis demonstrates the high status and undisputed authority of the episcopate as presented by Eusebius of Caesarea. The research of this thesis contributes to an understanding of the bishop in Roman society before Imperial favour

Detectors for the James Webb Space Telescope Near-Infrared Spectrograph I: Readout Mode, Noise Model, and Calibration Considerations

We describe how the James Webb Space Telescope (JWST) Near-Infrared Spectrograph's (NIRSpec's) detectors will be read out, and present a model of how noise scales with the number of multiple non-destructive reads sampling-up-the-ramp. We believe that this noise model, which is validated using real and simulated test data, is applicable to most astronomical near-infrared instruments. We describe some non-ideal behaviors that have been observed in engineering grade NIRSpec detectors, and demonstrate that they are unlikely to affect NIRSpec sensitivity, operations, or calibration. These include a HAWAII-2RG reset anomaly and random telegraph noise (RTN). Using real test data, we show that the reset anomaly is: (1) very nearly noiseless and (2) can be easily calibrated out. Likewise, we show that large-amplitude RTN affects only a small and fixed population of pixels. It can therefore be tracked using standard pixel operability maps.Comment: 55 pages, 10 figure