Additional Remediation Research Articles

Permeable reactive interceptors: blocking diffuse nutrient and greenhouse gases losses in key areas of the farming landscape

SUMMARYEngineered remediation technologies such as denitrifying bioreactors target single contaminants along a nutrient transfer continuum. However, mixed contaminant discharges to a water body are more common from agricultural systems. Indeed, evidence presented herein indicates that pollution swapping within denitrifying bioreactor systems adds to such deleterious discharges. The present paper proposes a more holistic approach to contaminant remediation on farms, moving from the use of ‘denitrifying bioreactors’ to the concept of a ‘permeable reactive interceptor’ (PRI). Besides management changes, a PRI should contain additional remediation cells for specific contaminants in the form of solutes, particles or gases. Balance equations and case studies representing different geographic areas are presented and used to create weighting factors. Results showed that national legislation with respect to water and gaseous emissions will inform the eventual PRI design. As it will be expensive to monitor a system continuously in a holistic manner, it is suggested that developments in the field of molecular microbial ecology are essential to provide further insight in terms of element dynamics and the environmental controls on biotransformation and retention processes within PRIs. In turn, microbial and molecular fingerprinting could be used as anin-situcost-effective tool to assess nutrient and gas balances during the operational phases of a PRI.

Identification and prevention of deleterious effects of supplementary health products on medical therapy ñ A challenge for clinical pharmacists

BackgroundIn the last decade it has become a challenging problem for the pharmaceutical profession that alongside their prescribed drug treatment patients take supplementary products (OTC, herbal remedies, food supplements, ‘panacea’...

Assessing the Cr(VI) reduction efficiency of a permeable reactive barrier using Cr isotope measurements and 2D reactive transport modeling

In Thun, Switzerland, a permeable reactive barrier (PRB) for Cr(VI) reduction by gray cast iron was installed in May 2008. The PRB is composed of a double array of vertical piles containing iron shavings and gravel. The aquifer in Thun is almost saturated with dissolved oxygen and the groundwater flow velocities are ca. 10-15m/day. Two years after PRB installation Cr(VI) concentrations still permanently exceed the Swiss threshold value for contaminated sites downstream of the barrier at selected localities. Groundwater δ(53/52)Cr(SRM979) measurements were used to track Cr(VI) reduction induced by the PRB. δ(53/52)Cr(SRM979) values of two samples downstream of the PRB showed a clear fractionation towards more positive values compared to four samples from the hotspot, which is clear evidence of Cr(VI) reduction induced by the PRB. Another downstream sample did not show a shift to more positive δ(53/52)Cr(SRM979) values. Because this latter location correlates with the highest downstream Cr(VI) concentration it is proposed that a part of the Cr(VI) plume is bypassing the barrier. Using a Rayleigh fractionation model a minimum present-day overall Cr(VI) reduction efficiency of ca. 15% was estimated. A series of 2D model simulations, including the fractionation of Cr isotopes, confirm that only a PRB bypass of parts of the Cr(VI) plume can lead to the observed values. Additionally, the simulations revealed that the proposed bypass occurs due to an insufficient permeability of the individual PRB piles. It is concluded that with this type of PRB a complete and long-lasting Cr(VI) reduction is extremely difficult to achieve for Cr(VI) contaminations located in nearly oxygen and calcium carbonate saturated aquifer in a regime of high groundwater velocities. Additional remediation action would limit the environmental impact and allow to reach target concentrations.

Kinetics and mechanisms of sulfate radical oxidation of β-lactam antibiotics in water

The quantitative removal of contaminant antibiotic activity from waters intended for reuse is one of the biggest problems facing water utilities today. As conventional water treatments are not sufficient, advanced Oxidation and Reduction Processes (AO/RPs) are being considered for additional remediation. In support of the potential use of sulfate radical based AO/RPs, we have determined the reaction rate constants for the sulfate radical with a large library of β-lactam antibiotics. The SO 4 - reactivity with the five-member ring species was found to have an extrapolated zero ionic strength average rate constant of (1.6 ± 0.9) × 10 9 M −1 s −1, slightly slower than for the six-member antibiotics at (2.1 ± 0.6) × 10 9 M −1 s −1. Transient spectral studies indicated that the majority of these radicals reacted at the five- or six-member rings adjacent to the β-lactam core, predominately at the sulfur atom and the double bond, respectively. As these oxidations occur next to the β-lactam moiety, rather than at the peripheral aromatic rings observed for hydroxyl radical reaction, sulfate radical remediation through the use of added persulfate might result in more efficient antibiotic activity removal than when using a traditional AO/RP treatment.

Detailed Investigation of the Radical-Induced Destruction of Chemical Warfare Agent Simulants in Aqueous Solution

The persistence of delivered chemical warfare agents (CWAs) in a variety of environmental matrices is of serious concern to both the military and civilian populations. Ultimately understanding all of the degradation pathways of the various CWAs in different environmental matrices is essential for determining whether native processes would offer sufficient decontamination of a particular material or if active chemical decontamination is required. Whereas much work on base-promoted chemical degradation has been reported, additional remediation strategies such as the use of advanced oxidation or reduction process free radical treatments may also be a viable option. We have examined here the primary kinetics and reaction mechanisms for an extensive library of chemical warfare agent simulants with the oxidizing hydroxyl radical and reducing hydrated electrons in water. From these values, it is seen that the reductive destruction occurs primarily through a single mechanism, consisting of hydrated electron capture at the phosphorus group with subsequent elimination, whereas hydroxyl radical oxidation shows two separate reaction mechanisms, dependent on the aqueous pK(a) of the leaving group.

Assessment steers learning down the right road: Impact of progress testing on licensing examination performance

Although it is generally accepted that assessment steers learning, this is generally viewed as an undesirable side effect. Recent evidence suggests otherwise. Experimental studies have shown that periodic formative assessments can enhance learning over equivalent time spent in study (Roediger & Karpicke 2006). However, positive effects of assessment at a curriculum level have not been demonstrated. Progress tests are a periodic formative assessment designed to enhance learning by providing objective and cumulative feedback, and by identifying a subgroup of students who require additional remediation. McMaster adopted the progress test methods in 1992–1993, as a consequence of poor performance on a national licensing examination. This article shows the positive effect of this innovation, which amounts to an immediate increase of about one-half standard deviation in examination scores, and a consistent upward trend in performance. The immediate effect of introducing objective tests was a reduction in failure rate on the licensing examination from 19% to 4.5%. Various reasons for this improvement in performance are discussed.

Design of effective remediation system in a contaminated aquifer by controlling constraints

Optimization of groundwater remediation design using the pump and treat method was modeled under controlled concentration constraint conditions. The remediation design in a contaminated aquifer with a heterogeneous hydraulic conductivity field was optimized by simultaneously minimizing the number of extraction wells and total extraction volume. A simulation-optimization method was applied to search for optimal designs. When the contaminant concentration constraint intensified, both the extraction volume and number of extraction wells generally increased. However, the number of wells, well locations, and extraction volume did not increase regularly according to changes in the constraint condition. These variations imply that remediation cost should be optimized by adjusting constraint conditions. Under the intensified constraints, the cleanup time changed ahead of the increase of the extraction rates, and the removal efficiency of contaminant decreased. It shows that a cost-effective remediation strategy using the pump and treat method could be achieved by increasing the cleanup time rather than extraction rates or introducing additional remediation techniques.

Monitored natural attenuation of organic contaminants in groundwater: principles and application

This paper reviews the conceptual and technical basis underpinning the use of monitored natural attenuation (MNA) for the management of organic contaminants in groundwater. MNA has important advantages over engineered remediation technologies for groundwater. Its significance will increase across the international community generally and its application for the management of petroleum hydrocarbons and other aromatic compounds will expand. Its application to other contaminants such as chlorinated solvents requires further qualification, although it has demonstrable potential for these. Long-term dissolution of non-aqueous-phase liquid (NAPL) sources is a major issue affecting remediation time-frames for MNA. Source zone remediation in conjunction with MNA will be required for many contaminated sites to meet typical regulatory time-frames permitted for MNA application. Internationally, there is general consensus in the scientific basis and assessment methods included in the technical guidance or protocols supporting the application of MNA. It is not a ’do-nothing’ remediation strategy, but requires site-specific characterisation, scientifically based analysis and a long-term commitment to monitoring, data collection and rigorous technical evaluation for ongoing performance assessment. Additional remediation technologies may be required to support MNA during the remediation programme and the decision to implement MNA should consider the large body of MNA literature that now exists and is summarised here.

아토피 피부염 치료를 위한 심신의학적 접근

아토피 피부염은 그 증상이 심각하고 그와 더불어 환자의 심리적 상태도 통제할 수 없을 정도로 황폐화되는 난치성 질환이다. 최근 연구보고들에 따르면 이 질환에 스트레스와 같은 심리적 요인이 중요하게 작용하며, 심리적 문제를 치료하는데 사용되는 기법들이 이 질환에도 유효하게 작용한다고 한다. 따라서 여기에서는 심리적 스트레스를 완화시켜 다양한 정신신체질환을 예방하고 치료하기 위한 목적으로 널리 사용되는 심신의학 프로그램을 아토피 질환의 추가적 치료 수단으로 제안하였다. 또한 심신의학 프로그램 의 치료 효과 모형과 치료자가 갖추어야 할 요건에 대해서도 논의하였다. Patients with atopic dermatitis, an intractable disease, suffer uncontrollable psychological distress as well as various symptoms in their skin. Recent findings showed that mental factors such as stress may play a role in the disease and that some techniques for alleviating psychological problems were efficacious in the atopic dermatitis. Therefore, we proposed the mind-body medicine that has been used to decrease the negative influences of stress and to cure psychosomatic disorders as an additional remedy for the atopic dermatitis. A model on the therapeutic effect of mind-body medicine and some qualities of practician also were discussed.

Modeling remediation time using natural attenuation at a dry-cleaner site

Contaminants from dry-cleaning sites, primarily tetrachloroethene (PCE), trichloroethene (TCE), cis-dichloroethene (cis-DCE), and vinyl chloride (VC), have become a major concern because of the limited funds and regulatory programs to address them. Thus, natural attenuation and its effectiveness for these sites needs to be evaluated as it might provide a less costly alternative to other remediation methods. In this research, data from a site in Texas were analyzed and modeled using the Biochlor analytical model to evaluate remediation times using natural attenuation. It was determined that while biodegradation and source decay were occurring at the site, the resulting attenuation rates were not adequate to achieve cleanup in a reasonable time frame without additional source remediation or control strategies. Cleanup times exceeded 100 years for all constituents at the site boundary and 800 years at the source for PCE, assuming cleanup levels of 0.005 mg/L for PCE and TCE and 0.07 mg/L and 0.002 mg/L for cis-DCE and VC, respectively. © 2005 Wiley Periodicals, Inc.

Monitored Natural Attenuation of Chlorinated Solvents: Assessment of Potential and Limitations

Chlorinated solvent contaminations in groundwater and soil are a widespread problem. Their remediation either by active and/or passive measures is complicated though, due to their characteristic features of long plumes and DNAPL. In this study Monitored Natural Attenuation (MNA) is evaluated regarding its applicability to remediate chlorinated solvent sites. At first a short overview of legal requirements is given, by whose means the efficiency of MNA is supposed to be demonstrated and assessed. Thereby the focus is set on the circumstances in the United States and Germany, as in the first MNA is applied as remediation option, whereas in the latter implementation and definition of MNA is under discussion. Based on criteria given by several German guidelines investigation methods and suitable parameters are discussed with the objective to evaluate their potential and limitations to demonstrate MNA at a chlorinated solvent site. Regarding the description of source location/inventory and source emission the legal requirements cannot be accomplished mainly because of missing methods. With regard to the characterization of plume migration, and evaluation of the efficiency of NA processes the combination of hydrogeochemical data and model approaches can accomplish most of the legal requirements. Applicability of microbiological and isotope methods is limited which is also reflected by evaluation of field studies, where these methods have been used at less than 10% of the sites. With regard to chlorinated solvents current German guidelines should be modified to enable the feasible application of MNA as an alternative or additional remediation option.

Geostatistical Approach for Assessing Soil Volumes Requiring Remediation: Validation Using Lead-Polluted Soils underlying a Former Smelting Works

Assessing the volume of soil requiring remediation and the accuracy of this assessment constitutes an essential step in polluted site management. If this remediation volume is not properly assessed, misclassification may lead both to environmental risks (polluted soils may not be remediated) and financial risks (unexpected discovery of polluted soils may generate additional remediation costs). To minimize such risks, this paper proposes a geostatistical methodology based on stochastic simulations that allows the remediation volume and the uncertainty to be assessed using investigation data. The methodology thoroughly reproduces the conditions in which the soils are classified and extracted at the remediation stage. The validity of the approach is tested by applying it on the data collected during the investigation phase of a former lead smelting works and by comparing the results with the volume that has actually been remediated. This real remediated volume was composed of all the remediation units that were classified as polluted after systematic sampling and analysis during clean-up stage. The volume estimated from the 75 samples collected during site investigation slightly overestimates (5.3% relative error) the remediated volume deduced from 212 remediation units. Furthermore, the real volume falls within the range of uncertainty predicted using the proposed methodology.

Quantification of groundwater contamination in an urban area using integral pumping tests

In this paper, the integral groundwater investigation method is used for the quantification of PCE and TCE mass flow rates at an industrialized urban area in Linz, Austria. In this approach, pumping wells positioned along control planes perpendicular to the groundwater flow direction are operated for a time period on the order of days and sampled for contaminants. The concentration time series of the contaminants measured during operation of the pumping wells are then used to determine contaminant mass flow rates, mean concentrations and the plume shapes and positions at the control planes. The three control planes used in Linz were positioned downstream of a number of potential source zones, which are distributed over the field site. By use of the integral investigation method, it was possible to identify active contaminant sources, quantify the individual source strength in terms of mass flow rates at the control planes and estimate the contaminant plume position relative to the control planes. The source zones emitting the highest PCE and TCE mass flow rates could be determined, representing the areas where additional investigation and remediation activities will be needed. Additionally, large parts of the area investigated could be excluded from further investigation and remediation activities.

The formation of autunite (Ca(UO 2) 2(PO 4) 2[rad]nH 2O) within the leached layer of dissolving apatite: incorporation mechanism of uranium by apatite

We carried out experiments of U(VI) uptake by fluorapatite (FAp) plate samples with a U(VI) concentration of 4.0×10 −4 mol·l −1, at final pHs ranging from 2.3 to 4.0 and at 25 °C to elucidate U(VI) uptake mechanisms. The U(VI) uptake by FAp increased with decreasing pH, which is in contrast with typical cation uptake by minerals where adsorption increases with increasing pH. Although the solutions were undersaturated with respect to autunite, Ca(UO 2) 2(PO 4) 2 nH 2O, a layer of autunite was in the FAp leached layer. If we assumed that pH was 1.3 times higher or U(VI) or P concentration was 40 times higher locally than the respective observed values in the bulk solutions, the local solutions were calculated to be supersaturated with respect to autunite. Our results strongly suggest that autunite formation is caused by local saturation in the leached layer even when a bulk solution is undersaturated with respect to autunite. Rutherford backscattering spectrometry (RBS) revealed that the thickness of the autunite layer increased with decreasing pH or with increasing time, i.e., with increasing dissolution of FAp, and that the concentration of U in the autunite layer was not significantly changed with time at constant pH. These indicate that the autunite layer becomes thicker without increasing the distribution density of autunite in the autunite layer as the reaction proceeds. RBS also revealed that a leached layer of FAp, where FAp was dissolving, was present between fresh FAp and the autunite layer, and characterized by a lower U concentration than that in the autunite layer and by higher and lower Ca concentrations than those in the autunite layer and FAp, respectively. Our results by RBS strongly suggest that the surface mineralization proceeds in the leached layer by local saturation and that autunite formed is finally added to and accumulated in the autunite layer. The surface mineralization in the leached layer explains the concurrent increases in U(VI) uptake, autunite-layer thickness and dissolution of FAp with decreasing pH or with increasing reaction time. Uranium(VI) uptake experiments were separately carried out on FAp powder samples with U(VI) concentrations of 4.0×10 −4 and 4.0×10 −6 mol·l −1, which resulted in autunite precipitation and U(VI) adsorption, respectively, for the uptake mechanisms. Surface mineralization should be taken into account for remediation and radioactive waste disposal in addition to adsorption and precipitation.

Durability of cognitive remediation training in schizophrenia: performance on two memory tasks at 6-month and 12-month follow-up

Patients with schizophrenia have consistently been found to exhibit cognitive deficits, particularly in memory, which have been suggested to mediate functional outcomes. Several recent reviews of cognitive retraining have concluded that these deficits respond to training, although the sustainability of cognitive improvement following completion of training has not been adequately evaluated. Most studies had small samples and very short follow-up periods. As part of a larger study, we examined performance on two memory tasks in two groups of participants: those who received computerized cognitive remediation training in addition to work therapy ( n=45), vs. those who only received work therapy ( n=49). Computerized cognitive remediation included hierarchical training on a computerized digit span task and a computerized words serial position task. Assessments using the same computerized tasks were made at three time points: baseline, end of active intervention, and 6-month follow-up. Compared to the active control condition (work therapy only), the group receiving computerized cognitive remediation in addition to work therapy showed significantly greater improvements on the trained digit span task following training. These improvements were maintained at the 6-month follow-up. There were no significant group differences on the word serial position task at any time point. Results indicate that computerized training can lead to sustained improvements on some, but not all, training tasks.

Part 4: Confidentiality and the duty of disclosure (Sub‐group 4: Impact of the initiatives on other areas of the law)

Examines the consequences of disclosing confidential information in the context of provisions of Sections 19 and 20 of the Terrorism Act 2002. Covers criminal law, intermediate law, and civil law, including common law and equitable duties of confidence, defences, and remedies, and the foreign element. Analyses the scheme of Sections 19 and 20 and the relationships between them, breach of obligations and defences against it in English law, removal of defences and additional defences, unfounded suspicions and remedies, remedies, uncompensated and compensated loss of rights. Concludes that although the Act may function well as a criminal law statute, it is not necessarily so good at dealing with the civil issue of breach of confidentiality: despite the defences to breach of confidence claims in Sections 19 and 20, civil entities are at risk.

Bioremediation of a PCB-Contaminated Soil Via Composting

Polychlorinated biphenyls (PCBs) were widely used in the past and now contaminate many industrial and natural areas. In this study, a PCB-contaminated soil from a former paper mill was mixed with a yard trimmings amendment and composted in field scale piles to determine the effect of soil to amendment ratio on PCB degradation. Temperature, oxygen concentrations, and a number of other environmental parameters that influence microbial activity during composting were monitored. The PCBs in contaminated soil had a concentration of 16 ±1 mg/kg dw and an average of 4 chlorines per biphenyl. The soil was composted with five levels of yard trimmings amendment (14% to 82% by weight) in pilot scale compost piles (25 m3) turned once per month. Results showed up to a 40% loss of PCBs with amendment levels of 60% and 82%. Congener specific PCB analysis indicated that less chlorinated PCB congeners (1-3 chlorines per biphenyl) were preferentially degraded. Bench-scale studies indicated that less than 1% of the PCBs in the contaminated soil were volatilized from composts during incubation with forced aeration at 55°C. In conclusion, PCB loss observed during the composting of the PCB-contaminated soil appeared to be largely due to biodegradation and not volatilization. Effective bioremediation of aged PCB-contaminated soils may require coupling of composting with additional remediation technologies to reduce levels of PCB congeners with greater than 4 chlorines.

Medical Antitrust Reform: Arrow, Coase and the Changing Structure of the Firm

The collapse of national health care reform has focused attention on private markets as the primary mechanism driving change in medical markets, but physicians and hospitals continue to seek legislation changing the antitrust rules that govern those markets. Physicians seek reforms that would permit greater collective action against third party payors. Hospitals want rules governing mergers relaxed to permit greater collective decision making in the allocation of medical resources. These proposals present a direct challenge to the prerogative of private markets and raise questions over when markets should be trusted and when they should be supplemented or displaced with social institutions. Kenneth Arrow envisions a range of possible non-market institutions filling the optimality gaps caused by medical market failures. Ronald Coase's theory of the firm provides a framework for understanding the transformation of the health care industry and for determining which interventions are likely to be helpful and which are likely to be harmful in emerging medical markets. This paper examines these theories and proposes a set of evaluative criteria for assessing health care reforms, concluding that appropriate non-market interventions should (1) be targeted at correcting recognized market failures; (2) result in a net increase in social welfare (static efficiency); and (3) not structurally interfere with the prospective development of efficient market operations (dynamic efficiency). Physician and hospital antitrust reforms are then evaluated in light of these criteria. Physician calls to collectively bargain or to form physician networks in the absence of substantial integration are largely unpersuasive. Antitrust rules should be defined in terms of structural economic considerations that are likely to facilitate more rational behavior in the health care sector. Permitting physician combinations or collective bargaining without integration or risk sharing will not yield the same economic benefits and will likely frustrate future market development. Hospital antitrust reforms raise a different set of questions. The central issue is whether greater cooperation among hospitals is necessary to counteract rent dissipating forms of non-price competition - the so-called medical arms race. While such claims possessed a plausible economic foundation in pre-integrated health care markets, the claims are outdated and unpersuasive by contemporary standards. Integrated firms directly internalize the costs of underutilized capital and equipment and are likely to make appropriate investment decisions. Moreover, to the extent that excess hospital capacity does exist in many markets, such capacity will play an important role in ensuring that future health care markets are maximally competitive. Rather than justifying exceptions to antitrust laws, emerging medical markets call for vigilant antitrust enforcement. Competition between integrated health plans not only facilitates lower prices, it also checks the most significant danger associated with integration: the potential under provision of care. Whether such competitive forces will be sufficient, or whether additional remedies are called for, particularly in markets too small to engender effective competition, remains an important policy question.

Implementation of the MARSSIM philosophy to evaluate the remedial status of a radioactive waste disposal site at the Idaho National Engineering and Environmental Laboratory. Multi-Agency Radiation Survey and Site Investigation Manual.

Implementation of the MARSSIM remedial-verification protocol at a radioactive waste disposal site is described in some detail to provide a record of the utility of this process. The selected site was the Stationary Low-Power Reactor No. 1 burial ground at the Idaho National Engineering and Environmental Laboratory. Evaluation was restricted to 137Cs in the uppermost 10 cm of potentially contaminated soils. According to the MARSSIM, this site warranted a "Class 1" designation based on previous remedial activities within the burial ground, its status as a radioactive disposal facility, and the anticipated presence of discrete radioactive particles. Nine survey units within the confines of the burial ground were selected, based primarily on the presence of physical boundaries and disparate histories. Surface scans with 100% coverage were performed using a hand-held plastic scintillator and rate meter with audible output. In situ gamma-ray spectrometry was not used for the individual stationary measurements due to the limited area and proximity of engineered barriers. Instead, individual soil samples were obtained using a standard hand-held coring device. The number of soil samples taken from the background reference area and each survey unit were determined with the MARSSIM protocol, which resulted in a total of 160 (including quality-control samples). Two of the nine regions exhibited elevated radiation levels and the null hypothesis could not be rejected in one survey unit, thereby indicating the need for additional remediation. The MARSSIM process proved to be flexible, scientifically rigorous, and cost effective in this field application. Several modifications to the procedure are discussed and offered as recommendations for enhancement of the MARSSIM.

Contaminated Sediment Management in the Great Lakes Basin Ecosystem

Contaminated sediment remains a pervasive problem to the restoration and delisting in all of the Great Lakes Areas of Concern. Like many other problems, both identification and implementation of ecologically and economically acceptable solutions is complex. Recognizing the scope of this issue and perceiving that limited progress had been achieved, the International Joint Commission (IJC) asked its Great Lakes Water Quality Board to review the magnitude of the problem and what progress had been made in managing contaminated sediment by Canada and the United States. In addition, the Commission also asked for an identification of obstacles to remediation and recommendations for solutions. This paper provides a synopsis of this work and a summary of an IJC workshop held in June of 1997, in Collingwood, Ontario. Six categories of obstacles to sediment remediation are discussed, potential solutions are identified, and a series of recommendations are proposed. A plan of action to further develop approaches to sediment management and to stimulate additional remediation throughout the basin is also presented.