Anionic surfactant remediation of soil columns contaminated by nonaqueous phase liquids

A variety of column experiments have been completed for the purpose of selecting and evaluating suitable surfactants for remediation of nonaqueous phase liquids (NAPLs). The various NAPLs tested in the laboratory experiments were tetrachloroethylene (PCE), trichloroethylene (TCE), jet fuel (JP4) and a dense nonaqueous phase liquid from a site at Hill Air Force Base, UT. Both Ottawa sand and Hill field soil were used in these experiments. Surfactant candidates were first screened using phase behavior experiments and only the best ones were selected for the subsequent column experiments. Surfactants which showed high contaminant solubilization, fast coalescence times, and the absence of liquid crystal phases and gels during the phase behavior experiments were tested in soil column experiments. The primary objective of the soil column experiments was to identify surfactants that recovered at least 99% of the contaminant. The secondary objective was to identify surfactants that show low adsorption and little or no loss of hydraulic conductivity during the column experiments. Results demonstrated that up to 99.9% of the contaminants were removed as a result of surfactant flooding of the soil columns. The addition of xanthan gum polymer to the surfactant solution was shown to increase remediation efficiency as a lower volume of surfactant was required for recovering a given volume of NAPL. Based on these experimental results, guidelines for designing highly efficient and robust surfactant floods have been developed and applied to a field demonstration.     

An epidemiologic comparison of injuries presenting to a pediatric emergency department and local urgent care facilities

Problem

The objective of this study was to compare the epidemiology of injuries presenting to emergency department (ED) and urgent care (UC) facilities of a single, NEISS-affiliated hospital.

Method

Patient medical records (n = 36,811) were used to compare injury incidence, injury characteristics, and demographic characteristics between the ED, on-site UC, and off-site UC during 2006.

Results

ED presentations were more likely to be open wounds and motor vehicle-related compared to on-site UC presentations. ED presentations were more likely to be system wide/late effects, be made by an African American, or be paid through Medicaid compared to off-site UC presentations. On-site UC presentations were more likely to be made by an African American or be paid through Medicaid compared to off-site UC presentations.

Discussion

ED and UC injury characteristics and patient demographics differ. With no nationally-representative UC injury surveillance, current research likely underestimates injury incidence and presents skewed profiles. Impact on Industry: This article adds insight into the generalizability of ED-based injury surveillance to UC injuries.     

Bioaugmentation with butane-utilizing microorganisms to promote in situ cometabolic treatment of 1,1,1-trichloroethane and 1,1-dichloroethene

A field study was performed to evaluate the potential for in-situ aerobic cometabolism of 1,1,1-trichloroethane (1,1,1-TCA) through bioaugmentation with a butane enrichment culture containing predominantly two Rhodococcus sp. strains named 179BP and 183BP that could cometabolize 1,1,1-TCA and 1,1-dicholoroethene (1,1-DCE). Batch tests indicated that 1,1-DCE was more rapidly transformed than 1,1,1-TCA by both strains with 183BP being the most effective organism. This second in a series of bioaugmentation field studies was conducted in the saturated zone at the Moffett Field In Situ Test Facility in California. In the previous test, bioaugmentation with an enrichment culture containing the 183BP strain achieved short term in situ treatment of 1,1-DCE, 1,1,1-TCA, and 1,1-dichloroethane (1,1-DCA). However, transformation activity towards 1,1,1-TCA was lost over the course of the study. The goal of this second study was to determine if more effective and long-term treatment of 1,1,1-TCA could be achieved through bioaugmentation with a highly enriched culture containing 179BP and 183BP strains. Upon bioaugmentation and continuous addition of butane and dissolved oxygen and or hydrogen peroxide as sources of dissolved oxygen, about 70% removal of 1,1,1-TCA was initially achieved. 1,1-DCE that was present as a trace contaminant was also effectively removed ( 80%). No removal of 1,1,1-TCA resulted in a control test leg that was not bioaugmented, although butane and oxygen consumption by the indigenous populations was similar to that in the bioaugmented test leg. However, with prolonged treatment, removal of 1,1,1-TCA in the bioaugmented leg decreased to about 50 to 60%. Hydrogen pexoxide (H₂O₂) injection increased dissolved oxygen concentration, thus permitting more butane addition into the test zone, but more effective 1,1,1-TCA treatment did not result. The results showed bioaugmentation with the enrichment cultures was effective in enhancing the cometabolic treatment of 1,1,1-TCA and low concentrations of 1,1-DCE over the entire period of the 50-day test. Compared to the first season of testing, cometabolic treatment of 1,1,1-TCA was not lost. The better performance achieved in the second season of testing may be attributed to less 1,1-DCE transformation product toxicity, more effective addition of butane, and bioaugmentation with the highly enriched dual culture.     

An ecological perspective on theory, methods, and analysis in environmental psychology: Advances and challenges

Over the course of environmental psychology's brief history, there has been an interest in ecologically oriented approaches to theory and research. Based on this work, this paper identifies a set of six principles of ecological analysis that present theoretical, methodological, and analytic challenges to future research in environmental psychology. These challenges include the theoretical treatment of the multiple contexts within which human experience and behavior occurs, the need for sampling both persons and environments, the modeling of moderating and mediating processes, the issue of self-selection into and out of different settings, the necessity of considering temporal factors in environmental research, reliance on single methods (e.g., verbal report) in data generation, cross-sectional and longitudinal research designs, and the need for greater use of statistical techniques developed for contextual (multi-level) research. These issues are discussed and illustrated using recent developments in environmentally oriented research. The paper concludes with a set of 11 recommendations for the future.     

Windsor, Ontario exposure assessment study: design and methods validation of personal, indoor, and outdoor air pollution monitoring

The Windsor, Ontario Exposure Assessment Study evaluated the contribution of ambient air pollutants to personal and indoor exposures of adults and asthmatic children living in Windsor, Ontario, Canada. In addition, the role of personal, indoor, and outdoor air pollution exposures upon asthmatic children's respiratory health was assessed. Several active and passive sampling methods were applied, or adapted, for personal, indoor, and outdoor residential monitoring of nitrogen dioxide, volatile organic compounds, particulate matter (PM; PM-2.5 pm [PM2.5] and < or =10 microm [PM10] in aerodynamic diameter), elemental carbon, ultrafine particles, ozone, air exchange rates, allergens in settled dust, and particulate-associated metals. Participants completed five consecutive days of monitoring during the winter and summer of 2005 and 2006. During 2006, in addition to undertaking the air pollution measurements, asthmatic children completed respiratory health measurements (including peak flow meter tests and exhaled breath condensate) and tracked respiratory symptoms in a diary. Extensive quality assurance and quality control steps were implemented, including the collocation of instruments at the National Air Pollution Surveillance site operated by Environment Canada and at the Michigan Department of Environmental Quality site in Allen Park, Detroit, MI. During field sampling, duplicate and blank samples were also completed and these data are reported. In total, 50 adults and 51 asthmatic children were recruited to participate, resulting in 922 participant days of data. When comparing the methods used in the study with standard reference methods, field blanks were low and bias was acceptable, with most methods being within 20% of reference methods. Duplicates were typically within less than 10% of each other, indicating that study results can be used with confidence. This paper covers study design, recruitment, methodology, time activity diary, surveys, and quality assurance and control results for the different methods used.     

Characterizing dissolved organic matter and evaluating associated nanofiltration membrane fouling

Natural organic matter (NOM) characteristics were determined for three ground waters exhibiting different water quality conditions. The water quality of the three feed waters collected at various water table depths was characterized by XAD-8/-4 resin adsorption, high performance size exclusion chromatography with ultraviolet and dissolved organic carbon (DOC) detections, and Fourier transform infrared spectroscopy (FTIR) to determine NOM fractionation, molecular weight, and NOM functional groups, respectively. Systematic studies were conducted to identify potential NOM foulants in ground water for nanofiltration (NF) membrane fouling. The results show that the hydrophobic fraction of NOM in all of the samples was significantly high (71-93%) compared to the hydrophilic (1.7-22.6%) and transphilic (5.3-6.6%) fractions. However, insignificant flux-decline (less than 5%) was observed for the highest DOC (36.9 mg l(-1)) and hydrophobic NOM (93%) containing groundwater compared to the other lesser DOC and hydrophobic NOM containing ground waters. This is presumably due to either higher fractions of hydrophilic and transphilic NOM or inorganic interactions that may be major foulants. Based on FTIR, aromatic foulants were observed at 1662 cm(-1) (CO-NH2 or CO conjugated with aromatic rings) for the fouled NF membrane with the relatively low DOC source waters. The contact angle of the clean membrane (52 degrees ) decreased with fouling up to 42-47 degrees for fouled membranes with the various samples.     

Pesticides in urban multiunit dwellings: hazard identification using classification and regression tree (CART) analysis

Many units in public housing or other low-income urban dwellings may have elevated pesticide residues, given recurring infestation, but it would be logistically and economically infeasible to sample a large number of units to identify highly exposed households to design interventions. Within this study, our aim was to devise a low-cost approach to identify homes in public housing with high levels of pesticide residues, using information that would allow the housing authority and residents to determine optimal strategies to reduce household exposures. As part of the Healthy Public Housing Initiative, we collected environmental samples from 42 public housing apartments in Boston, MA, in 2002 and 2003 and gathered housing characteristics; for example, household demographics and self-reported pesticide use information, considering information available with and without a home visit. Focusing on five organophosphate and pyrethroid pesticides, we used classification and regression tree analysis (CART) to disaggregate the pesticide concentration data into homogenous subsamples according to housing characteristics, which allowed us to identify households and associated networks impacted by the mismanagement of pesticides. The CART analysis demonstrated reasonable sensitivity and specificity given more extensive household information but generally poor performance using only information available without a home visit. Apartments with high concentrations of cyfluthrin, a pyrethroid of interest given that it is a restricted use pesticide, were more likely to be associated with Hispanic residents who resided in their current apartment for more than 5 yr, consistent with documented pesticide usage patterns. We conclude that using CART as an exploratory technique to better understand the home characteristics associated with elevated pesticide levels may be a viable approach for risk management in large multiunit housing developments.     

Evaluation of Reference Evapotranspiration Methods in Arid,Semiarid, and Humid Regions

It is often necessary to find a simpler method in different climatic regions to calculate reference crop evapotranspiration (ET_o) since the application of the FAO‐56 Penman‐Monteith method is often restricted due to the unavailability of a comprehensive weather dataset. Seven ET_o methods, namely the standard FAO‐56 Penman‐Monteith, the FAO‐24 Radiation, FAO‐24 Blaney Criddle, 1985 Hargreaves, Priestley‐Taylor, 1957 Makkink, and 1961 Turc, were applied to calculate monthly averages of daily ET_o, total annual ET_o, and daily ET_o in an arid region at Aksu, China, in a semiarid region at Tongchuan, China, and in a humid region at Starkville, Mississippi, United States. Comparisons were made between the FAO‐56 method and the other six simple alternative methods, using the index of agreement D, modeling efficiency (EF), and root mean square error (RMSE). For the monthly averages of daily ET_o, the values of D, EF, and RMSE ranged from 0.82 to 0.98, 0.55 to 0.98, and 0.23 to 1.00 mm/day, respectively. For the total annual ET_o, the values of D, EF, and RMSE ranged from 0.21 to 0.91, ?43.08 to 0.82, and 24.80 to 234.08 mm/year, respectively. For the daily ET_o, the values of D, EF, and RMSE ranged from 0.58 to 0.97, 0.57 to 0.97, and 0.30 to 1.06 mm/day, respectively. The results showed that the Priestly‐Taylor and 1985 Hargreaves methods worked best in the arid and semiarid regions, while the 1957 Makkink worked best in the humid region.     

Regulation of Indirect Sources

The Division of Air Pollution Control, Illinois Environmental Protection Agency, has conducted an ambient air quality monitoring project focusing on carbon monoxide levels in and around several indirect sources. An analysis of the data indicates that highway-type pollutant emissions have the greatest impact on receptors in the vicinity of indirect sources. This implies that the principal, localized constraint on the siting of indirect sources will be the carbon monoxide generated on public roadways servicing those indirect sources. Clearly, adequate procedures must be developed to link such highway-type emissions to pollutant concentrations. An area-source model and a line-source model were tested using the data generated during the monitoring project. Favorable results were achieved using the line-source model. The proper siting of indirect sources involves the allocation of roadway capacity by the governmental units responsible for transportation network design, working in conjunction with regional planning bodies. A regulatory structure is suggested which emphasizes a regional approach, and an example of an air quality allocation scheme is given. The methodology is applicable to all automotive air pollutants although, in general, localized sensitivity is lost for N0₂ and photochemical oxi-dants.     

Thiosulfate as an Oxidation Inhibitor in Flue Gas Desulfurization Processes: A Review of R&D Results

Sodium thiosulfate (Na₂S₂O₃) has been tested in a pilot plant as an oxidation inhibitor in flue gas desulfurization by lime and limestone slurry scrubbing with and without MgO and adiplc acid additives. The effectiveness of thiosulfate is proportional to the inhibitor product, defined as the product of thiosulfate concentration (M), calcium concentration (M), and the moles of SO₂ absorbed per hour per liter of hold tank volume. Gypsum saturation was less than 100 percent and scaling was eliminated when the inhibitor product exceeded 0.3 × 10^?6(gmol/L)³/h. Thiosulfate was relatively more effective in systems with chlorides and less effective in systems promoted by MgO. An inhibitor product greater than 10^?6(gmol/L)³/h significantly enhanced dewatering of solids from limestone scrubbing. SO₂ removal and/or limestone utilization were increased in systems that started with less than 10 mM dissolved calcium.