Remediation of multicomponent dense nonaqueous phase liquids in porous media

In 2004, the U.S. EPA estimated that as many as 45,000 former manufactured gas plants (FMGPs) required remediation of contaminated soil or groundwater. The primary contaminants at these sites are tars. FMGP tars are complex, dense nonaqueous phase liquids (DNAPLs), containing several thousand compounds including polycyclic aromatic hydrocarbons (PAHs). PAHs are sparingly soluble, but can dissolve from tars into groundwater at concentrations that exceed levels of concern. Tar DNAPLs can also sink below the water table and slowly migrate underground to impact waterbodies directly. Laboratory studies were conducted to investigate in-situ remediation methods that rely on physical and chemical means. Specifically, column studies were used to evaluate cosolvent flushing for removing PAHs from contaminated soil excavated from an FMGP in Salisbury, NC. These experiments were conducted at varying length scales, ranging from 11.9 to 110 cm. PAH effluent concentrations were modeled using a common two-site sorption model. Fitted mass-transfer rates were two to three orders of magnitude lower than predicted values based on published data. Laboratory studies were also conducted to determine how tar density and viscosity vary as a function of composition and temperature. For this work, samples of tars were obtained from wells at two FMGPs: one in Baltimore, MD and one in Portland, ME. The tar composition varied spatially across both sites. Empirical relationships were developed that can be used in predicting tar recovery during thermal remediation

Assessment and improvement of biotransfer models to cow’s milk and beef used in exposure assessment tools for organic pollutants

The aim of this study was to assess and improve the accuracy of biotransfer models for the organic pollutants (PCBs, PCDD/Fs, PBDEs, PFCAs, and pesticides) into cow’s milk and beef used in human exposure assessment. Metabolic rate in cattle is known as a key parameter for this biotransfer, however few experimental data and no simulation methods are currently available. In this research, metabolic rate was estimated using existing QSAR biodegradation models of microorganisms (BioWIN) and fish (EPI-HL and IFS-HL). This simulated metabolic rate was then incorporated into the mechanistic cattle biotransfer models (RAIDAR, ACC-HUMAN, OMEGA, and CKow). The goodness of fit tests showed that RAIDAR, ACC-HUMAN, OMEGA model performances were significantly improved using either of the QSARs when comparing the new model outputs to observed data. The CKow model is the only one that separates the processes in the gut and liver. This model showed the lowest residual error of all the models tested when the BioWIN model was used to represent the ruminant metabolic process in the gut and the two fish QSARs were used to represent the metabolic process in the liver. Our testing included EUSES and CalTOX which are KOW-regression models that are widely used in regulatory assessment. New regressions based on the simulated rate of the two metabolic processes are also proposed as an alternative to KOW-regression models for a screening risk assessment. The modified CKow model is more physiologically realistic, but has equivalent usability to existing KOW-regression models for estimating cattle biotransfer of organic pollutants

Age-related deficits in efficiency of low-level lateral inhibition

Background: In a masked prime task using a 0 ms prime-target inter-stimulus-interval, responses on trials where prime and target match (compatible trials) are usually faster and more accurate than responses where prime and target mismatch (incompatible trials). This positive compatibility effect (PCE) comprises both behavioral benefits on compatible relative to neutral trials, and behavioral costs on incompatible relative to neutral trials. Comparing performance in 2- vs. 4-alternative-response versions of the task indicates that benefits are due to direct priming (i.e., pre-activation) of a motor response, whereas costs reflect an inhibition of the alternative response tendency. The present study employs this paradigm to test the hypothesis that normal aging is associated with a selective deficit in inhibitory function, affecting both low-level motor and higher-level executive control. Experiment and Results: Testing 20 young and 20 older healthy adults, we found that (1) overall, prime-induced benefits were of similar magnitude across age groups, but inhibition-based costs were smaller in older compared to young adults; (2) increasing the number of response alternatives caused the same pattern of unaltered benefits and reduced costs in both age groups; and (3) costs, but not benefits, in the 2-alternative condition were significantly predicted by scores on the digit symbol substitution task (DSST), independently of age and other background variables. Interpretation: Results demonstrate the possibility of isolating an inhibitory component in low-level perceptuo-motor control. Importantly, this component shows an age-related decline in the absence of a corresponding decline of visuo-motor excitability, and appears to be linked to performance on a higher-level processing speed task. We hypothesize that aging might affect the brain's ability to establish precise short-term lateral inhibitory links, and that even in young adults, the efficiency of such links is a significant contributing factor in higher-level cognitive performance

Dense non-aqueous phase liquids at former manufactured gas plants: Challenges to modeling and remediation

The remediation of dense non-aqueous phase liquids (DNAPLs) in porous media continues to be one of the most challenging problems facing environmental scientists and engineers. Of all the environmentally relevant DNAPLs, tars in the subsurface at former manufactured gas plants (FMGP’s) pose one of the biggest challenges due to their complex chemical composition and tendency to alter wettability. To further our understanding of these complex materials, we consulted historic documentation to evaluate the impact of gas manufacturing on the composition and physicochemical nature of the resulting tars. In the recent literature, most work to date has been focused in a relatively narrow portion of the expected range of tar materials, which has yielded a bias toward samples of relatively low viscosity and density. In this work, we consider the dissolution and movement of tars in the subsurface, models used to predict these phenomena, and approaches used for remediation. We also explore the open issues and detail important gaps in our fundamental understanding of these extraordinarily complex systems that must be resolved to reach a mature level of understanding

A Case of Primary Pulmonary Lymphoma

Primary pulmonary lymphoma, which is constitutes only 0,5% of all lung tumors, is a rare tumor arising from in­trapulmonary lymphatics. Due to presentation with mass and consolidation, many diseases, require to be consid­ered in the differential diagnosis such as primary or meta­static lung cancer, pneumonia, pulmonary sequestration and atelectasis radiologically. A 44 years old male patient with complaints for two years, with 65x68 mm pulmo­nary mass lesion in left upper lobe and lingular segments which has boundaries could not be distinguished by heart border, was interned. Diagnostic thoracotomy applied and histopathology was obtained as pulmonary lymphoma. Wedge resection including lingula and lower lobe api­cal segments was performed. In this study, we aimed to present a case hospitalized with complaints of cough and fatigue and diagnosed as primary pulmonary ( low-grade B-cell) lymphoma

Mass mimicking tuberculosis cases diagnosed postoperatively

Tüberküloz farklı radyolojik görünümlerle ortaya çıkabilen bir hastalıktır. Sık olmamakla birlikte kitle görünümünde akciğer tüberkülozu olguları literatürde mevcuttur. Akciğerde kitle görünümü ile başvuran hastalarda tüberküloz tanısından emin olmak ve eşlik eden tümör tanısını kesin dışlamak bazen zor olmaktadır. Bu yazıda, kliniğimize akciğer grafiğinde kitle görünümü ile başvuran 42 ve 65 yaşındaki iki hastanın tanısında yaşanan güçlükler tartışıldı. Her iki olgunun bilgisayarlı tomografileri sonrası, Pozitron Emisyon Tomografileri çekildi. Üç kez bakılan balgamda Aside rezistans bakteri negatif idi. Fiberoptik bronkoskopik lavaj ve bronş biyopsileri negatif geldi. Bu nedenle her iki olguya cerrahi ile tanıya gidildi. İlk olguya mini torakotomi ile wedge rezeksiyonu yapıldı. Alınan parankim dokudan frozen (donmuş kesit) çalışıldı ve tüberkülozla uyumlu geldi. İkinci olgununda cerrahi sırasında frozen malign gelmesi nedeniyle sol üst lobektomi yapıldı. Ancak kesin patoloji raporu tüberküloz olarak geldi. Her iki olguya anti-tüberküloz tedavisi başlandı ve rutin kontrollerinde genel durumları iyi idi. Ülkemiz gibi tüberkülozun yaygın görüldüğü yerlerde akciğerde kitle görüntüsünde olan lezyonların değerlendirilmesinde tüberkülozun akılda tutulması gerekir.Tuberculosis is a disease that occurs with different radiological manifestations. Although not frequent, tuberculosis cases seen as pulmonary masses have been reported in the literature. It is difficult to diagnose pulmonary tuberculosis definitely and to rule out a tumor in patients presenting with image of a pulmonary mass. In this paper, we discussed difficulties in diagnosis of two patients, aged 42 and 65 years, who admitted with a mass image on their chest x-rays to our clinic. Positron emission tomography images were taken following computerized tomography. Acid fast bacteria, bronchoalveolar lavage and bronchoscopic biopsies were not diagnostic. Therefore, surgery was used to establish the diagnosis. In the first patient, lobectomy was carried out with wedge resection due to peroperative suspected malignancy report of frozen section. Definitive report, however, yielded tuberculosis. Both patients received antituberculosis treatment and both were well at routine follow up examinations. Tuberculosis should be kept in mind when a mass is encountered in an endemic area such as our country. J Clin Exp Invest 2014; 5 (3): 462-46

Mobilization of Manufactured Gas Plant Tar with Alkaline Flushing Solutions

This experimental study investigates the use of alkaline and alkaline-polymer solutions for the mobilization of former manufactured gas plant (FMGP) tars. Tar-aqueous interfacial tensions (IFTs) and contact angles were measured, and column flushing experiments were conducted. NaOH solutions (0.01–1 wt.%) were found to significantly reduce tar-aqueous IFT. Contact angles indicated a shift to strongly water-wet, then to tar-wet conditions as NaOH concentration increased. Column experiments were conducted with flushing solutions containing 0.2, 0.35, and 0.5% NaOH, both with and without xanthan gum (XG). Between 10 and 44% of the residual tar was removed by solutions containing only NaOH, while solutions containing both NaOH and XG removed 81–93% of the tar with final tar saturations as low as 0.018. The mechanism responsible for the tar removal is likely a combination of reduced IFT, a favorable viscosity ratio, and tar bank formation. Such an approach may have practical applications and would be significantly less expensive than surfactant-based methods

Cosolvent flushing for the remediation of PAHs from former manufactured gas plants

Cosolvent flushing is a technique that has been proposed for the removal of hydrophobic organic contaminants in the subsurface. Cosolvents have been shown to dramatically increase the solubility of such compounds compared to the aqueous solubility; however, limited data are available on the effectiveness of cosolvents for field-contaminated media. In this work, we examine cosolvent flushing for the removal of polycyclic aromatic hydrocarbons (PAHs) in soil from a former manufactured gas plant (FMGP). Batch studies confirmed that the relationship between the soil-cosolvent partitioning coefficient (Ki) and the volume fraction of cosolvent (fc) followed a standard log-linear equation. Using methanol at an fc of 0.95, column studies were conducted at varying length scales, ranging from 11.9 to 110 cm. Removal of PAH compounds was determined as a function of pore volumes (PVs) of cosolvent flushed. Despite using a high fc, rate and chromatographic effects were observed in all the columns. PAH effluent concentrations were modeled using a common two-site sorption model. Model fits were improved by using MeOH breakthrough curves to determine fitted dispersion coefficients. Fitted mass-transfer rates were two to three orders of magnitude lower than predicted values based on published data using artificially contaminated sands