3,445 research outputs found
Recommended from our members
TECHNICAL EVALUATION OF THE INTERACTION OF GROUNDWATER WITH THE COLUMBIA RIVER AT THE DEPARTMENT OF ENERGY HANFORD SITE 100-D AREA
Groundwater beneath much of Hanford's 100 Areas is contaminated with hexavalent chromium (Cr{sup +6}) as a consequence of treating reactor cooling water to prevent corrosion. Several treatment systems are in place to remove Cr{sup +6} from the groundwater; however, these systems currently do not reduce Cr{sup +6} to concentrations below aquatic standards. Of concern is the transport of Cr{sup +6} to areas within the channel of the river, as sensitive species inhabit the river and its associated transition zone. The aquatic standard for Cr{sup +6} is currently 11 ug/l under the Record of Decision (ROD) for Interim Action and Department of Energy (DOE) currently plans to pursue remediation of the groundwater to achieve the 11 ug/l standard. Because the compliance wells used to monitor the current remediation systems are located some distance from the river, they may not provide an accurate indication of Cr{sup +6} concentrations in the water that reaches the riverbed. In addition, because salmon spawning areas are considered a high priority for protection from Hanford contaminants, it would be advantageous to understand (1) to what extent Cr{sup +6} discharged to the near-shore or river ecosystems is diluted or attenuated and (2) mechanisms that could mitigate the exposure of the river ecosystems to the discharging Cr{sup +6}. The current concentration target for Cr{sup +6} at near-river groundwater monitoring locations is 20 {micro}g/L; it is assumed that this groundwater mixes with river water that contains virtually no chromium to meet Washington Department of Ecology's (Ecology) water quality standard of 10 {micro}g/L in the river environment. This dynamic mixing process is believed to be driven by daily and seasonal changes in river stage and groundwater remediation system operations, and has been validated using analytical data from numerous groundwater samples obtained adjacent to and within the banks of the river. Although the mean mixing factor of river water and site groundwater in this zone has been estimated to be equal parts of groundwater and river water, a wide range of mixing ratios likely occurs at various times of the day and year. The degree of mixing and dilution appears to be greatly influenced by the river stage and other groundwater/surface water interaction. The extent of mixing, thus, has implications for the design and operation of the groundwater remediation systems. Improved understanding of this 'dilution' mechanism is needed to design an optimum 'systems approach' to accelerate remediation of the near-shore contaminant plumes. More information on the pathway from near-river mapped plumes to riverbed receptor locations is also needed to develop a defensible proposed plan for a future ROD for final remedial action of contaminated groundwater. In April 2008, an expert panel of scientists was convened to review existing information and provide observations and suggestions to improve the current understanding of groundwater surface water interactions in the 100 Areas (primarily focusing on 100-D Area), and to identify what additional analyses or approaches may provide critical information needed to design and implement remediation systems that will minimize impacts to river aquatic systems. Specific objectives provided to the panel included: (1) comment on approaches and methods to improve the current understanding of groundwater-surface water interactions, specifically how contaminated groundwater enters the riverbed and how this relates to remediation of chromate in the groundwater in the 100 Areas; (2) evaluate past and current data collection methods, data analysis techniques, assumptions, and groundwater transport and mixing mechanisms; (3) evaluate the current monitoring network (monitoring wells, aquifer tubes, and shoreline/river monitoring); (4) evaluate the role played by modeling; and (5) suggest additional research to fill data gaps and perform modeling
Recommended from our members
TECHNICAL EVALUATION OF ELECTRICAL RESISTIVITY METHODS AT THE DEPARTMENT OF ENERGY HANFORD SITE
Recommended from our members
TESTING GROUND BASED GEOPHYSICAL TECHNIQUES TO REFINE ELECTROMAGNETIC SURVEYS NORTH OF THE 300 AREA HANFORD WASHINGTON
Airborne electromagnetic (AEM) surveys were flown during fiscal year (FY) 2008 within the 600 Area in an attempt to characterize the underlying subsurface and to aid in the closure and remediation design study goals for the 200-PO-1 Groundwater Operable Unit (OU). The rationale for using the AEM surveys was that airborne surveys can cover large areas rapidly at relatively low costs with minimal cultural impact, and observed geo-electrical anomalies could be correlated with important subsurface geologic and hydrogeologic features. Initial interpretation of the AEM surveys indicated a tenuous correlation with the underlying geology, from which several anomalous zones likely associated with channels/erosional features incised into the Ringold units were identified near the River Corridor. Preliminary modeling resulted in a slightly improved correlation but revealed that more information was required to constrain the modeling (SGW-39674, Airborne Electromagnetic Survey Report, 200-PO-1 Groundwater Operable Unit, 600 Area, Hanford Site). Both time-and frequency domain AEM surveys were collected with the densest coverage occurring adjacent to the Columbia River Corridor. Time domain surveys targeted deeper subsurface features (e.g., top-of-basalt) and were acquired using the HeliGEOTEM{reg_sign} system along north-south flight lines with a nominal 400 m (1,312 ft) spacing. The frequency domain RESOLVE system acquired electromagnetic (EM) data along tighter spaced (100 m [328 ft] and 200 m [656 ft]) north-south profiles in the eastern fifth of the 200-PO-1 Groundwater OU (immediately adjacent to the River Corridor). The overall goal of this study is to provide further quantification of the AEM survey results, using ground based geophysical methods, and to link results to the underlying geology and/or hydrogeology. Specific goals of this project are as follows: (1) Test ground based geophysical techniques for the efficacy in delineating underlying geology; (2) Use ground measurements to refine interpretations of AEM data; and (3) Improve the calibration and correlation of AEM information. The potential benefits of this project are as follows: (1) Develop a tool to map subsurface units at the Hanford Site in a rapid and cost effective manner; (2) Map groundwater pathways within the River Corridor; and (3) Aid development of the conceptual site model. If anomalies observed in the AEM data can be correlated with subsurface geology, then the rapid scanning and non-intrusive capabilities provided by the airborne surveys can be used at the Hanford Site to screen for areas that warrant further investigation
Recommended from our members
SCIENCE AND TECHNOLOGY ACTIVITIES FOR CHROMIUM IN THE 100 AREAS
{sm_bullet} Primary Objective: Protect the Columbia River - Focus is control and treatment of contamination at or near the shoreline, which is influenced by bank storage {sm_bullet} Secondary Objective: Reduce hexavalent chromium to <48 parts per billion (ppb) in aquifer (drinking water standard) - Large plumes with isolated areas of high chromium concentrations (> 40,000 ppb), - Unknown source location(s); probably originating in reactor operation area
Recommended from our members
DEVELOPMENT OF A GEOCHEMICAL MODEL FOR URANIUM TRANSPORT IN THE UNSATURATED AND SATURATED SEDIMENTS AT THE 200 WEST AREA OF THE US DEPARTMENT OF ENERGY HANFORD SITE WASHINGTON (SEPTEMBER 2004)
Final Deliverable under GWP-HQ-LMT-02 contract for Hanford Sci. & Tech. Gp. to BHI. The scope of work covered laboratory analyses and gephysical logging for 299-W19-43 near the 200 West U Plant. Other isotopic analyses were conducted for holes around 216-U-1&2, including U-236
Recommended from our members
TREATABILITY TEST FOR REMOVING TECHNETIUM-99 FROM 200-ZP-1 GROUNDWATER HANFORD SITE
The 200-ZP-1 Groundwater Operable Unit (OU) is one of two groundwater OUs located within the 200 West groundwater aggregate area of the Hanford Site. The primary risk-driving contaminants within the 200-ZP-1 OU include carbon tetrachloride and technetium-99 (Tc-99). A pump-and-treat system for this OU was initially installed in 1995 to control the 0.002 kg/m{sup 3} (2000 {micro}g/L) contour of the carbon tetrachloride plume. Carbon tetrachloride is removed from groundwater with the assistance of an air-stripping tower. Ten extraction wells and three injection wells operate at a combined rate of approximately 0.017m{sup 3}/s (17.03 L/s). In 2005, groundwater from two of the extraction wells (299-W15-765 and 299-W15-44) began to show concentrations greater than twice the maximum contaminant level (MCL) of Tc-99 (33,309 beq/m{sup 3} or 900 pCi/L). The Tc-99 groundwater concentrations from all ten of the extraction wells when mixed were more than one-half of the MCL and were slowly increasing. If concentrations continued to rise and the water remained untreated for Tc-99, there was concern that the water re-injected into the aquifer could exceed the MCL standard. Multiple treatment technologies were reviewed for selectively removing Tc-99 from the groundwater. Of the treatment technologies, only ion exchange was determined to be highly selective, commercially available, and relatively low in cost. Through research funded by the U.S. Department of Energy, the ion-exchange resin Purolite{reg_sign} A-530E was found to successfully remove Tc-99 from groundwater, even in the presence of competing anions. For this and other reasons, Purolite{reg_sign} A-530E ion exchange resin was selected for treatability testing. The treatability test required installing resin columns on the discharge lines from extraction wells 299-W15-765 and 299-W15-44. Preliminary test results have concluded that the Purolite{reg_sign} A-530E resin is effective at removing Tc-99 from groundwater to below detection limits even in the presence of competing anions (e.g., nitrate and sulfate) at concentrations five to six magnitudes higher than Tc-99
Recommended from our members
TREATABILITY TEST PLAN FOR DEEP VADOSE ZONE REMEDIATION AT THE HANFORD SITE CENTRAL PLATEAU
A treatability test plan has been prepared to address options for remediating portions of the deep vadose zone beneath a portion of the U.S. Department of Energy's (DOE's) Hanford Site. The vadose zone is the region of the subsurface that extends from the ground surface to the water table. The overriding objective of the treatability test plan is to recommend specific remediation technologies and laboratory and field tests to support the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 and Resource Conservation and Recovery Act of 1976 remedial decision-making process in the Central Plateau of the Hanford Site. Most of the technologies considered involve removing water from the vadose zone or immobilizing the contaminants to reduce the risk of contaminating groundwater. A multi-element approach to initial treatability testing is recommended, with the goal of providing the information needed to evaluate candidate technologies. The proposed tests focus on mitigating two contaminants--uranium and technetium. Specific technologies are recommended for testing at areas that may affect groundwater in the future, but a strategy to test other technologies is also presented
Implications for the conservation of deep-water corals in the face of multiple stressors: A case study from the New Zealand region
Optimising use of electronic health records to describe the presentation of rheumatoid arthritis in primary care: a strategy for developing code lists
Background
Research using electronic health records (EHRs) relies heavily on coded clinical data. Due to variation in coding practices, it can be difficult to aggregate the codes for a condition in order to define cases. This paper describes a methodology to develop ‘indicator markers’ found in patients with early rheumatoid arthritis (RA); these are a broader range of codes which may allow a probabilistic case definition to use in cases where no diagnostic code is yet recorded.
Methods
We examined EHRs of 5,843 patients in the General Practice Research Database, aged ≥30y, with a first coded diagnosis of RA between 2005 and 2008. Lists of indicator markers for RA were developed initially by panels of clinicians drawing up code-lists and then modified based on scrutiny of available data. The prevalence of indicator markers, and their temporal relationship to RA codes, was examined in patients from 3y before to 14d after recorded RA diagnosis.
Findings
Indicator markers were common throughout EHRs of RA patients, with 83.5% having 2 or more markers. 34% of patients received a disease-specific prescription before RA was coded; 42% had a referral to rheumatology, and 63% had a test for rheumatoid factor. 65% had at least one joint symptom or sign recorded and in 44% this was at least 6-months before recorded RA diagnosis.
Conclusion
Indicator markers of RA may be valuable for case definition in cases which do not yet have a diagnostic code. The clinical diagnosis of RA is likely to occur some months before it is coded, shown by markers frequently occurring ≥6 months before recorded diagnosis. It is difficult to differentiate delay in diagnosis from delay in recording. Information concealed in free text may be required for the accurate identification of patients and to assess the quality of care in general practice
black hole at N=2 supergravity
In this paper, we consider the charged non-extremal black hole at five
dimensional N = 2 supergravity. We study thermodynamics of AdS_{5} black hole
with three equal charges (q_{1} = q_{2} = q_{3} = q). We obtain Schrodinger
like equation and discuss the effective potential. Then, we consider the case
of the perturbed dilaton field background and find presence of odd coefficients
of the wave function. Also we find that the higher derivative corrections have
no effect on the first and second even coefficients of the wave function.Comment: 17 pages, 4 figures. Published versio
- …