Formation of Manganese Oxide Coatings onto Sand for Adsorption of Trace Metals from Groundwater.

Manganese oxide (MnO) occurs naturally in soil and has a high affinity for trace metals adsorption. In this work, we quantified the factors (pH; flow rate; use of oxidants such as bleach, HO, and O; initial Mn(II) concentrations; and two types of geologic media) affecting MnO coatings onto Ottawa and aquifer sand using batch and column experiments. The batch experiments consisted of manual and automated titration, and the column experiments mimicked natural MnO adsorption and oxidation cycles as a strategy for in situ adsorption. A Pb solution of 50 mg L was passed through MnO-coated sand at a flow rate of 4 mL min to determine its adsorption capacity. Batch experimental results showed that MnO coatings increased from pH 6 to 8, with maximum MnO coating occurring at pH 8. Regarding MnO coatings, bleach and O were highly effective compared with HO. The Ottawa sand had approximately twice the MnO coating of aquifer sand. The sequential increase in initial Mn(II) concentrations on both sands resulted in incremental buildup of MnO. The automated procedure enhanced MnO coatings by 3.5 times compared with manual batch experiments. Column results showed that MnO coatings were highly dependent on initial Mn(II) and oxidant concentrations, pH, flow rate, number of cycles (h), and the type of geologic media used. Manganese oxide coating exceeded 1700 mg kg for Ottawa sand and 130 mg kg for aquifer sand. The Pb adsorption exceeded 2200 mg kg for the Ottawa sand and 300 mg kg for the aquifer sand.

Geochemical parameters influencing tungsten mobility in soils.

The biogeochemistry of tungsten and its effects on mobility have recently gained attention due to the existence of human cancer clusters, such as in Fallon, NV. Tungsten exists in many environmental matrices as the soluble and mobile tungstate anion. However, tungsten can polymerize with itself and other anions, creating poly- and heteropoly-tungstates with variable geochemical and toxicological properties. In the present work, geochemical parameters are determined for tungstate species in a model soil that describe the potential for tungsten mobility. Soluble tungsten leached from a metallic tungsten-spiked soil after six to twelve months aging reached an equilibrium concentration >150 mg/L within 4 h of extraction with deionized water. Partition coefficients determined for various tungstate and polytungstate compounds in the model soil suggest a dynamic system in which speciation changes over time affect tungsten geochemical behavior. Partition coefficients for tungstate and some poly-species have been observed to increase by a factor of 3 to 6 over a four month period, indicating decreased mobility with soil aging.

Effects of organic matter on the distribution of uranium in soil and plant matrices.

This work studied interactions of uranium with pure organic compounds, such as glutathione, and more complex mixtures, such as humic acid and aqueous plant extracts. High performance liquid chromatography with UV absorption interfaced to inductively coupled plasma mass spectrometry sequential detection was used to detect organouranium complexes in a variety of soils and plant materials, indicating that nearly 100% of the uranium extracted from certain plant tissues was bound to organic ligands. In addition, soil sorption experiments indicated that humic acid generally decreased uranium sorption to soils and promoted subsequent desorption of uranium because of uranium partitioning to the organic phase. These experiments demonstrate that organic compounds influence the mobility and chemistry of uranium in the environment.

Gravity Spy: integrating advanced LIGO detector characterization, machine learning, and citizen science.

With the first direct detection of gravitational waves, the advanced laser interferometer gravitational-wave observatory (LIGO) has initiated a new field of astronomy by providing an alternative means of sensing the universe. The extreme sensitivity required to make such detections is achieved through exquisite isolation of all sensitive components of LIGO from non-gravitational-wave disturbances. Nonetheless, LIGO is still susceptible to a variety of instrumental and environmental sources of noise that contaminate the data. Of particular concern are noise features known as glitches, which are transient and non-Gaussian in their nature, and occur at a high enough rate so that accidental coincidence between the two LIGO detectors is non-negligible. Glitches come in a wide range of time-frequency-amplitude morphologies, with new morphologies appearing as the detector evolves. Since they can obscure or mimic true gravitational-wave signals, a robust characterization of glitches is paramount in the effort to achieve the gravitational-wave detection rates that are predicted by the design sensitivity of LIGO. This proves a daunting task for members of the LIGO Scientific Collaboration alone due to the sheer amount of data. In this paper we describe an innovative project that combines crowdsourcing with machine learning to aid in the challenging task of categorizing all of the glitches recorded by the LIGO detectors. Through the Zooniverse platform, we engage and recruit volunteers from the public to categorize images of time-frequency representations of glitches into pre-identified morphological classes and to discover new classes that appear as the detectors evolve. In addition, machine learning algorithms are used to categorize images after being trained on human-classified examples of the morphological classes. Leveraging the strengths of both classification methods, we create a combined method with the aim of improving the efficiency and accuracy of each individual classifier. The resulting classification and characterization should help LIGO scientists to identify causes of glitches and subsequently eliminate them from the data or the detector entirely, thereby improving the rate and accuracy of gravitational-wave observations. We demonstrate these methods using a small subset of data from LIGO's first observing run.

Characterization of a military training site containing 232Thorium.

Understanding contaminant distribution is critical to selection and implementation of effective and affordable containment and remediation efforts. This article describes the characterization of soil containing thorium at a training site on Kirtland Air Force Base, Albuquerque, NM. The site has been used by the Defense Nuclear Weapons School since the early 1960's to train personnel in emergency response to nuclear weapons accidents and for characterization and containment of radioactive contamination. The purpose of work reported herein is to describe the primary location and migration pattern of 232Thorium (232Th) and 232Th progeny (decay products) at the site. Soil containing thorium oxide (ThO2) was applied to the site for approximately 30 years (early 1960-1990) and was used to simulate a plutonium release from a nuclear weapons accident. Data presented indicate that surface 232Th and 232Th progeny at approximately 5 times background levels are approaching test site boundaries. However, the data also indicate that vertical migration has not exceeded 0.9 m because of the insoluble nature of ThO2. The major mechanisms of 232Th mobility appear to be surface migration mediated by precipitation runoff and wind-blown soil.

Depressive disorder, dysthymia, and risk of stroke: thirteen-year follow-up from the Baltimore epidemiologic catchment area study.

BACKGROUND AND PURPOSE: This study examined depressive disorder as a risk factor for incident stroke in a prospective, population-based design. METHODS: The Baltimore Epidemiologic Catchment Area Study is a prospective 13-year follow-up of a probability sample of household residents from Baltimore, Md. Depressive disorder was measured with the diagnostic interview schedule, and stroke was assessed by questions from the health interview survey or by documentation on a death certificate. RESULTS: During the 13-year follow-up of 1703 individuals, 66 strokes were reported and 29 strokes were identified by death certificate search. Individuals with a history of depressive disorder were 2.6 times more likely to report stroke than those without this disorder after controlling for heart disease, hypertension, diabetes, and current and previous use of tobacco. Medications used in the treatment of depressive disorder at baseline did not alter this finding. A history of dysthymia demonstrated a similar relationship to stroke, although the estimate was not statistically significant. CONCLUSIONS: Depressive disorder is a risk factor for stroke that appears to be independent of traditional cardiovascular risk factors. Further research on mechanisms for the association and the impact of treatment for depressive disorder on subsequent stroke is needed.

Computer-assisted scheduling of radiology resident call.

The difficulties inherent in assigning an entire residency group fair and equivalent daily call prompted the development of a computerized scheduling program at The University of Texas at Houston. Written in COBOL, the program is run on a CDC mainframe computer. Logic parameters restrict the number and frequency of calls per month, and each resident is coded for five available call types at two university hospitals. The foundation of the program's operation is an arbitrary point scale applied to each call type determined by its difficulty and time commitment. Residents' point totals each month are roughly balanced within a prescribed range, with call exchanges made by the computer if necessary. The computer-generated schedules are flexible and equitable, require little manual correction, and save time for the chief resident and the residency secretary.

Fate of explosive contaminants in plants.

A great deal of interest has been generated recently in the determination of explosives and explosives by-products in exotic matrices including composts, bioslurries, and plants. The methods traditionally utilized for the analysis of organic and inorganic contaminants in these types of environmental samples are not adequate owing to the unique properties of the material being studied. The methods used to detect the nitramines and their degradation products in a variety of environmental samples requires matrix-specific sample preparation, separation by reversed phase high performance liquid chromatography, and ultra-violet detection. Knowledge of the concentration of the contaminants and the molecular state of their degradation products is helpful in assessing the environmental risks associated with the contaminants as well as the design of remediation technologies. Data that are obtained using analytical methods not designed for the specific matrix encountered may lead to incorrect quantitation. Examples of remediation technologies that necessitate the analysis of other than standard matrices for explosives include composting, aerobic and anaerobic microbial degradation, and plant-assisted degradation. The toxicity and mobility of explosives in the food chain are also of interest, and analytical techniques for studying explosives in plant and animal tissues that provide valid information regarding trace levels in these matrices are also required. The report will address three important points in connection with the problem. The extraction of the contaminants from the matrix requires a different set of extraction techniques than those utilized for standard water and soil extractions. These exotic matrices contain much higher organic content than soil or water and, as a result, are prone to interference from biological molecules.

Screening of aquatic and wetland plant species for phytoremediation of explosives-contaminated groundwater from the Iowa Army Ammunition Plant.

The results of this study indicate that the presence of plants did enhance TNT and TNB removal from IAAP groundwater. Most effective at 25 degrees C were reed canary grass, coontail and pondweed. Groundwater and plant tissue analyses indicate that in presence of the plants tested TNT is degraded to reduced by-products and to other metabolites that were not analyzed. TNT removal was best modeled using first order kinetics, with rate constants at 25 degrees C incubations ranging from 0.038 microgram L-1 h-1 for reed canary grass to 0.012 microgram L-1 h-1 for parrot-feather. These kinetics predict hydraulic retention times (HRTs) ranging from 4.9 days to 19.8 days to reach a TNT concentration of 2 micrograms L-1. Decreasing incubation temperature to 10 degrees C affected reed canary grass more than parrot-feather, increasing estimated HRTs by factors of four and two, respectively. The plant species tested showed a far lower potential for RDX removal from the IAAP groundwater. Most effective at 25 degrees C were reed canary grass and fox sedge. Analyses of plant material indicated the presence of RDX in under-water plant portions and in aerial plant portions, and RDX accumulation in the latter. RDX removal was best modeled using zero order kinetics, with rate constants for the 25 degrees C incubation ranging from 13.45 micrograms L-1 h-1 for reed canary grass to no removal in four species. Based on these kinetics, estimated HRTs to reach 2 micrograms L-1 RDX increased from 39 days. Decreasing the temperature to 10 degrees C increased HRT 24-fold for reed canary grass. By using the biomass-normalized K value, submersed plants are identified as having the highest explosives-removing activity (microgram explosive L-1 h-1 g DW-1). However, biomass production of submersed plants is normally five to ten times less than that of emergent plants per unit area, and, thus, in plant selection for wetland construction, both, explosives removal potential and biomass production are important determinants.

Do parent practices to encourage academic competence influence the social adjustment of young European American and Chinese American children?

The predominant early childhood education philosophy in the United States views formal academic instruction as inappropriate and harmful to the social development of young children. Chinese American immigrants to the United States, however, have been found to teach their young children in more formal ways, to be more directive, and to structure their children's use of time to a greater degree (C. S. Huntsinger, P. E. Jose, F.-R. Liaw, & W.-D. Ching, 1997). Forty European American (20 boys, 20 girls) and 36 2nd-generation Chinese American (18 boys, 18 girls) 1st- and 2nd-grade children and their mothers, fathers, and teachers participated in the Time 2 data collection of this longitudinal study to assess whether the formal academic environment provided by Chinese American parents is linked to poorer social adjustment in their children. Regressions showed that parents' work-oriented methods influenced academic performance but not social adjustment of their children.

Environmental behavior of explosives in groundwater from the Milan Army Ammunition Plant in aquatic and wetland plant treatments. Removal, mass balances and fate in groundwater of TNT and RDX.

Phytoremediation of 2,4,6-trinitrotoluene (TNT) and hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) in groundwater using constructed wetlands is a potentially economical remediation alternative. To evaluate Explosives removal and fate was evaluated using hydroponic batch incubations of plant and substrate treatments with explosives-contaminated groundwater amended with [U-14C]-TNT or [U-14C]-RDX. Plants and substrates were collected from a small-scale wetland constructed for explosives removal, and groundwater originated from a local aquifer at the Milan Army Ammunition Plant. The study surveyed three aquatic, four wetland plant species and two substrates in independent incubations of 7 days with TNT and 13 days with RDX. Parent compounds and transformation products were followed using 14C and chemical (HPLC) analyses. Mass balance of water, plants, substrates and air was determined. It was demonstrated that TNT disappeared completely from groundwater incubated with plants, although growth of most plants except parrot-feather was low in groundwater amended to contain 1.6 to 3.4 mg TNT L-1. Highest specific removal rates were found in submersed plants in water star-grass and in all emergent plants except wool-grass. TNT declined less with substrates, and least in controls without plants. Radiolabel was present in all plants after incubation. Mineralization to 14CO2 was very low, and evolution into 14C-volatile organics negligible. RDX disappeared less rapidly than TNT from groundwater. Growth of submersed plants was normal, but that of emergent plants reduced in groundwater amended to contain 1.5 mg RDX L-1. Highest specific RDX removal rates were found in submersed plants in elodea, and in emergent plants in reed canary grass. RDX failed to disappear with substrates. Mineralization to 14CO2 was low, but relatively higher than in the TNT experiment. Evolution into 14C-volatile organics was negligible. Important considerations for using certain aquatic and wetland plants in constructed wetlands aimed at removing explosives from water are: (1) plant persistence at the explosives level to which it is exposed, (2) specific plant-mass based explosives removal rates, (3) plant productivity, and (4) fate of parent compounds and transformation products in water, plants, and sediments.

Environmental behavior of explosives in groundwater from the Milan Army Ammunition Plant in aquatic and wetland plant treatments. Uptake and fate of TNT and RDX in plants.

Uptake and fate of TNT and RDX by three aquatic and four wetland plants were studied using hydroponic, batch, incubations in explosives-contaminated groundwater amended with [U-14C]-TNT or [U-14C]-RDX in the laboratory. Substrates in which the plants were rooted were also tested. Plants and substrates were collected from a small-scale wetland constructed for explosives removal, and groundwater originated from a local aquifer at the Milan Army Ammunition Plant. This study demonstrated rapid uptake of [U-14C]-TNT derived 14C, concentration at the uptake sites and limited transport in all plants. Per unit of mass, uptake was higher in submersed than in emergent species. Biotransformation of TNT had occurred in all plant treatments after 7-day incubation in 1.6 to 3.4 mg TNT L-i, with labeled amino-dinitrotoluenes (ADNTs), three unidentified compounds unique for plants, and mostly polar products as results. Biotransformation occurred also in the substrates, yielding labeled ADNT, one unidentified compound unique for substrates, and polar products. TNT was not recovered by HPLC in plants and substrates after incubation. Uptake of [U-14C]-RDX derived 14C in plants was slower than that of TNT, transport was substantial, and concentration occurred at sites where new plant material was synthesized. As for TNT, uptake per unit of mass was higher in submersed than in emergent species. Biotransformation of RDX had occurred in all plant treatments after 13-day incubation in 1.5 mg RDX L-1, with one unidentified compound unique for plants, and mostly polar products as results. Biotransformation had occurred also in the substrates, but to a far lower extent than in plants. Substrates and plants had one unidentified 14C-RDX metabolite in common. HPLC analysis confirmed the presence of RDX in most plants and in three out of four substrates at the end of the incubation period.

Mechanisms of thorium migration in a semiarid soil.

Thorium concentrations at Kirtland Air Force Base training sites in Albuquerque, NM, have been previously described; however, the mechanisms of thorium migration were not fully understood. This work describes the processes affecting thorium mobility in this semiarid soil, which has implications for future remedial action. Aqueous extraction and filtration experiments have demonstrated the colloidal nature of thorium in the soil, due in part to the low solubility of thorium oxide. Colloidal material was defined as that removed by a 0.22-microm or smaller filter after being filtered to nominally dissolved size (0.45 microm). Additionally, association of thorium with natural organic matter is suggested by micro- and ultrafiltration methods, and electrokinetic data, which indicate thorium migration as a negatively charged particle or anionic complex with organic matter. Soil fractionation and digestion experiments show a bimodal distribution of thorium in the largest and smallest size fractions, most likely associated with detrital plant material and inorganic oxide particles, respectively. Plant uptake studies suggest this could also be a mode of thorium migration as plants grown in thorium-containing soil had a higher thorium concentration than those in control soils. Soil erosion laboratory experiments with wind and surface water overflow were performed to determine bulk soil material movement as a possible mechanism of mobility. Information from these experiments is being used to determine viable soil stabilization techniques at the site to maintain a usable training facility with minimal environmental impact.

Tolerance towards explosives, and explosives removal from groundwater in treatment wetland mesocosms.

A short-term study was performed to determine the feasibility of using constructed wetlands to remove explosives from groundwater, and to assess accumulation of parent explosives compounds and their known degradation compounds in wetland plants. Tolerance towards explosives in submersed and emergent plants was screened over a range of 0 to 40 mg L(-1). Tolerance varied per compound, with TNT evoking the highest, 2NT the lowest, and 24DNT, 26DNT, and RDX an intermediate growth reducing effect. Submersed plants were more sensitive to TNT than emergent ones. A small-scale 4-month field study was carried out at the Volunteer Army Ammunition Plant, Chattanooga, TN. In this surface-flow, modular system, the influent contained high levels (>2.1 mg L(-1)) of TNT, 2,4DNT, 2,6DNT, 2NT, 3NT, and 4NT, and the HRT was 7 days. The performance criteria of US EPA treatment goals for local discharge of 2,4DNT concentration <0.32 mg L(-1), and 26DNT concentration <0.55 mg L(-1) were not met at the end of the experiment, although explosives levels were greatly reduced. Low levels of 2ADNT and 4ADNT were transiently observed in the plant biomass. Results of two other, older, constructed wetlands, however, indicated that in these systems treatment goals were met most of the time, residues of explosives parent compounds and known degradation compounds in plant tissues were low and/or transient, and in substrates were low.

Preventable adverse patient outcomes: a closed claims analysis of respiratory incidents.

Closed claims analysis of adverse anesthesia outcomes was initiated through the AANA Foundation in 1995 to examine adverse outcomes of anesthesia care provided by Certified Registered Nurse Anesthetists (CRNAs). A research team of 8 CRNAs using an instrument incorporating more than 150 variables undertook document analyses of closed claim files. All files reviewed involved incidents in which the CRNA named in the policy was potentially involved in the adverse patient outcome. Thirty-eight percent (58/151) of CRNA-related claims involved a respiratory incident as the primary cause of the negative patient outcome. Patient outcomes involving respiratory incidents were more likely to result in death or permanent injury compared with nonrespiratory incidents (P < .01). Reviewers found that respiratory claims were more likely to have involved inappropriate anesthesia management (P < .01), more likely to have involved a lack of vigilance (P < .01), and more likely to have been judged by the reviewer as preventable (P < .01). A higher percentage of respiratory incidents occurred in emergency cases (75% vs 34%, P < .01) and in cases involving general anesthesia (44% vs 17%, P < .01). Adverse respiratory incidents are largely preventable and frequently result in serious patient morbidity and mortality.

Impact of molecular adsorbent recirculating system therapy on tacrolimus elimination: a case report.

BACKGROUND: We report a unique case which quantifies the effect of molecular adsorbent recirculating system (MARS [Gambro, Sweden]) therapy on blood concentrations of tacrolimus in a patient treated for refractory pruritus associated with recurrent hepatitis C of the liver allograft. Tacrolimus is a low-molecular-weight, highly protein-bound drug with the potential to be removed during MARS therapy. CASE REPORT: Results of therapeutic drug monitoring revealed extracorporeal tacrolimus elimination accounted for only 0.3% of total drug removal during the session. CONCLUSIONS: Although no explanation can be offered as to why MARS contributed so little to overall tacrolimus elimination, the data clearly show minimal impact of MARS on tacrolimus blood level.

Hydrated lime for metals immobilization and explosives transformation: Treatability study.

Fragmentation grenades contain Composition B (RDX and TNT) within a steel shell casing. There is the potential for off-site migration of high explosives and metals from hand grenade training ranges by transport in surface water and subsurface transport in leachate. This treatability study used bench-scale columns and mesocosm-scale laboratory lysimeters to investigate the potential of hydrated lime as a soil amendment for in situ remediation of explosives and metals stabilization in hand grenade range soils. Compared to the unamended soil there was a 26-92% reduction of RDX in the leachate and runoff water from the lime treated soils and a 66-83% reduction of zinc in the leachate and runoff water samples; where the hand grenade range metals of concern were zinc, iron, and manganese. The amended soil was maintained at the target pH of greater than 10.5 for optimum explosives decomposition. The treatability study indicated a high potential of success for scale-up to an in situ field study.