Tolerance to trichlorophenols in microorganisms from a polluted and a pristine site of a river

The effect of 2,4,5- and 2,4,6-trichlorophenol on the microbiota from a polluted and a pristine site of a river was studied. Bacterial metabolic activity measurements by epifluorescence microscopy showed that the polluted site contained more metabolically active cells than the pristine site. Total culturable bacterial counts and tolerant bacterial counts from both sites were not affected by incubation (for up to 5 days) with 200 ppm of chlorophenols. However, the incubation with 500 ppm of 2,4,5-trichlorophenol prevented detection of total and tolerant bacterial counts in the pristine site, and inhibited tolerants in the polluted site. None of 250 bacterial colonies directly isolated from these samples was able to grow on chlorophenols. However, bacteria able to grow on 2,4,6-trichlorophenol, were obtained by enrichment of water and sediments samples.     

Chromium Analysis at a Ferrochrome Smelter,a Chemical Plant and a Refractory Brick Plant

Techniques were developed to sample and analyze the Cr content of participate samples with emphasis on determining the concentration of the carcinogen Cr⁺⁶. Cr⁺⁶ is extracted to alkaline solution and analyzed colorimetrically. Residual particles are extracted with acid solution to remove soluble Cr⁺³, which is determined by atomic absorption spectrometry. This methodology was tested on samples from three diverse types of sources: a ferrochrome smelter, a chemical plant, and a refractory brick plant. Identical quadruplicate samples were collected to determine accuracy and precision of the collection and analysis procedures, and extraction of Cr⁺⁶ and Cr⁺³. A statistical analysis revealed that the precision of Cr⁺⁶ analysis is comparable to that of the particulate mass determination. The stability of Cr⁺⁶ In particulate form and in solution was determined. Size resolved particulate samples were collected to determine the particle size versus the Cr⁺⁶ content. At the ferrochrome smelter and the chemical plant the majority of the Cr⁺⁶ was contained in the respirable particles. The accuracy and completeness of the chemical methods employed were verified by neutron activation analysis, x-ray photoelectron spectroscopy, and scanning electron microscopyenergy dispersive x-ray analysis.     

Bioremediation of a weathered and a recently oil-contaminated soils from Brazil: a comparison study

The facility with which hydrocarbons can be removed from soils varies inversely with aging of soil samples as a result of weathering. Weathering refers to the result of biological, chemical and physical processes that can affect the type of hydrocarbons that remain in a soil. These processes enhance the sorption of hydrophobic organic contaminants (HOCs) to the soil matrix, decreasing the rate and extent of biodegradation. Additionally, pollutant compounds in high concentrations can more easily affect the microbial population of a recently contaminated soil than in a weathered one, leading to inhibition of the biodegradation process. The present work aimed at comparing the biodegradation efficiencies obtained in a recently oil-contaminated soil (spiked one) from Brazil and an weathered one, contaminated for four years, after the application of bioaugmentation and biostimulation techniques. Both soils were contaminated with 5.4% of total petroleum hydrocarbons (TPHs) and the highest biodegradation efficiency (7.4%) was reached for the weathered contaminated soil. It could be concluded that the low biodegradation efficiencies reached for all conditions tested reflect the treatment difficulty of a weathered soil contaminated with a high crude oil concentration. Moreover, both soils (weathered and recently contaminated) submitted to bioaugmentation and biostimulation techniques presented biodegradation efficiencies approximately twice as higher as the ones without the aforementioned treatment (natural attenuation).     

Biological treatment of a contaminated gaseous emission from a leather industry in a suspended-growth bioreactor

A suspended-growth bioreactor (SGB) was operated for the treatment of a gaseous stream mimicking emissions generated at a leather industrial company. The main volatile organic compounds (VOCs) present in the gaseous stream consisted of 1-methoxy-2-propanol, 2,6-dimethyl-4-heptanone, 2-butoxyethanol, toluene and butylacetate. A microbial consortium able to degrade these VOCs was successfully enriched. A laboratory-scale SGB was established and operated for 210-d with an 8h cycle period and with shutdowns at weekends. Along this period, the SGB was exposed to organic loads (OL) between 6.5 and 2.3 x 10(2) g h(-1) m(-3). Most of the compounds were not detected at the outlet of the SGB. The highest total VOC removal efficiency (RE) (ca 99%) was observed when an OL of 1.6 x 10(2) g h(-1) m(-3) was fed to the SGB. The maximum total VOC elimination capacity (1.8 x 10(2) g h(-1) m(-3)) was achieved when the OL applied to the SGB was 2.3 x 10(2) g h(-1) m(-3). For all the operating conditions, the SGB showed high levels of degradation of toluene and butylacetate (RE approximately equal to 100%). This study also revealed that recirculation of the gaseous effluent improved the performance of the SGB. Overall, the SGB was shown to be robust, showing high performance after night and weekend shutdown periods.     

The use of a high-FeO olivine rock as a redox buffer in a nuclear waste repository

Due to the higher stability of the spent nuclear fuel (mainly composed of UO2) under reducing conditions, and in order to enhance the retention/retardation of some key radionuclides, the olivine rock from the Lovasj?rvi intrusion has been proposed as a potential redox-active backfill-additive in deep high-level nuclear waste (HLNW) repositories. In this work, two different approaches have been undertaken in order to establish the redox buffer capacity of olivine rock: (1) The capacity of the rock to respond to changes in pH or pe has been demonstrated and the final (pH, pe) coordinates agree with the control exerted by the system Fe(II)/Fe(III). (2) The rate of consumption of oxygen has been determined at different pH values. These rates are higher than the ones reported in the literature for other solids, what would point to the possibility of using this rock as an additive to the backfill material in a HLNW.     

Environmental assessment on a soil washing process of a Pb-contaminated shooting range site: a case study

In this study, an environmental assessment on a soil washing process for the remediation of a Pb-contaminated shooting range site was conducted, using a green and sustainable remediation tool, i.e., SiteWise ver. 2, based on data relating specifically to the actual remediation project. The entire soil washing process was classified into four major stages, consisting of soil excavation (stage I), physical separation (stage II), acid-based (0.2 N HCl) chemical extraction (stage III), and wastewater treatment (stage IV). Environmental footprints, including greenhouse gas (GHG) emissions, energy consumption, water consumption, and critical air pollutant productions such as PM₁₀, NO _x , and SO _x , were calculated, and the relative contribution of each stage was analyzed in the environmental assessment. In stage I, the relative contribution of the PM₁₀ emissions was 55.3 % because the soil excavation emitted the fine particles. In stage II, the relative contribution of NO _x and SO _x emissions was 42.5 and 52.5 %, respectively, which resulted from electricity consumption for the operation of the separator. Stage III was the main contributing factor to 63.1 % of the GHG emissions, 67.5 % of total energy used, and 37.4 % of water consumptions. The relatively high contribution of stage III comes from use of consumable chemicals such as HCl and water-based extraction processes. In stage IV, the relative contributions of GHG emissions, total energy used, and NO _x and SO _x emissions were 23.2, 19.4, 19.5, and 25.3 %, respectively, which were caused by chemical and electricity demands for system operation. In conclusion, consumable chemicals such as HCl and NaOH, electric energy consumption for system operation, and equipment use for soil excavation were determined to be the major sources of environmental pollution to occur during the soil washing process. Especially, the acid-based chemical extraction process should be avoided in order to improve the sustainability of soil washing processes.     

Coping with uncertainty: a call for a new science-policy forum

The scientific and policy worlds have different goals, which can lead to different standards for what constitutes "proof" of a change or phenomena, and different approaches for characterizing and conveying uncertainty and risk. These differences can compromise effective communication among scientists, policymakers, and the public, and constrain the types of socially compelling questions scientists are willing to address. In this paper, we review a set of approaches for dealing with uncertainty, and illustrate some of the errors that arise when science and policy fail to coordinate correctly. We offer a set of recommendations, including restructuring of science curricula and establishment of science-policy forums populated by leaders in both arenas, and specifically constituted to address problems of uncertainty.     

On-road comparison of a portable emission measurement system with a mobile reference laboratory for a heavy-duty diesel vehicle

On-road comparisons were made between a mobile emissions laboratory (MEL) meeting federal standards and a portable emissions measurement system (PEMS). These comparisons were made over different conditions; including road grade, vibration, altitude, electric fields, and humidity with the PEMS mounted inside and outside of the tractor's cab. Brake-specific emissions were calculated to explore error differences between the MEL and PEMS during the Not-To-Exceed (NTE) engine operating zone. The PEMS brake-specific NOx (bsNOx) NTE emissions were biased high relative to the MEL and, in general, were about 8% of the 2007 in-use NTE NO_x standard of 2.68 g kW^?1 h^?1 (2.0 g hp^?1 h^?1). The bsCO₂ emissions for the PEMS were also consistently biased high relative to the MEL, with an average deviation of +4% ± 2%. NMHC and CO emissions were very low and typically less than 1% of the NTE threshold. This research was part of a comprehensive program to determine the “allowance” when PEMS are used for in-use compliance testing of heavy-duty diesel vehicles (HDDVs).     

Multiple radon entry modeling in a house with a cellar.

Combining a computational fluid dynamics (CFD) model and a multi-zonal model, a study was carried out on radon entry through the complex substructure of a house with a cellar. The uniqueness of the radon entry problem in this type of house was due to the involvement of two radon entry routes to two chambers: the cellar and the living area of the house. Soil gas carrying radon was driven through the two routes by two coupled disturbance pressures in the chambers. The effects of temperature differences were considered as another driving force for the radon entry. Examined in this study were the effects of the geometry of the substructure, air permeability of the soil, air-tightness of the cellar shell, and cellar ventilation on radon entry to both the cellar and the living area. The ground floor covering on top of the soil outside a cellar wall increased radon entry through this wall by about 68%, as radon built up to a very high level under the covering. The effect of cellar ventilation was found as follows: the cellar ventilation created a layer of airflow in the soil under the ground floor; the flow passed over a crack in the ground floor, the entry route to the living area, diluting the radon in the area. Hence, the soil gas entering the living area carried less radon. Cellar ventilation seems more effective in reducing radon entry to the living area in a more permeable soil and leaky cellar shell; a moderate cellar ventilation condition achieved 77% reduction in radon entry to the area. When permeability of these two materials was lower and soil radon content remained the same, the chances of radon entry was also lower; hence, the indoor radon level was lower and no radon control was needed. When such soil contains high radon concentration, other mitigation measures must be sought.     

Natural phillipsite as a matrix for a slow-release formulation of oxamyl

The performance of phillipsite as a matrix for slow-release formulation of oxamyl [N,N-dimethyl-2-methylcarbamoyl-oxymino-2-(methylthio)acetamide] was tested. The adsorption kinetics followed a first-order law, and the adsorption isotherm fitted well in a two-surface Langmuir model, suggesting a double mechanism of interaction between oxamyl and the sorbent. The sorption mechanism, studied by FTIR, provided two fractions of oxamyl. The first one is sorbed on the mineral surface, linked by H-bonding, and the second one is constituted by a multilayer of oxamyl molecules linked by a water bridge between them. The release kinetics of oxamyl from a substratum zeolite-oxamyl also follows a first-order law, with two stages that correspond to both fractions of oxamyl previously detected.     

Formulation of a soil-pesticide transport model based on a compartmental approach

A semianalytical soil-pesticide transport model is formulated based on a compartmental approach to determine spatial and temporal variations of pesticide residues across a soil profile. The compartmental model is implemented by drawing an analogy between a series of continuous-flow stirred tank reactors and a soil horizon that consists of multiple perfectly mixed compartments. The analogy is strengthened by exploiting a relation between the compartment series and the conventional convective-dispersive equation (CDE) for vertical transport in the soil. Consequently, the number of compartments in the model formulation is not free, but dictated as a function of transport parameters. The model formulation allows consideration of arbitrary boundary value specifications and also, for some cases, spatially varying initial concentration profiles. Sorption kinetics is represented via a two-site model that involves a linear sorption isotherm and a first-order irreversible sorption or a radial diffusive penetrating model. For these three cases, analysis of the compartmental model allows the resultant concentration profiles to be expressed in terms of the Poisson distribution. When a nonlinear kinetic sorption model is used to simulate the sorption processes, an analytical solution is not found and a numerical approach is required.     

Biofiltration Kinetics of a Gaseous Aldehyde Mixture Using a Synthetic Matrix

Abstract

Although aldehydes contribute to ozone and particulate matter formation, there has been little research on the biofiltration of these volatile organic compounds (VOCs), especially as mixtures. Biofiltration degradation kinetics of an aldehyde mixture containing hexanal, 2-methylbutanal (2-MB), and 3-methylbutanal (3-MB) was investigated using a bench-scale, synthetic, media-based biofilter. The adsorption capacity of the synthetic media for a model VOC, 3-methylbutanal, was 10 times that of compost. Periodic residence time distribution analysis (over the course of 1 yr) via a tracer study (84–99% recovery), indicated plug flow without channeling in the synthetic media and lack of compaction in the reactor. Simple first-order and zero-order kinetic models both equally fit the experimental data, yet analysis of the measured rate constants versus fractional conversion suggested an overall first-order model was more appropriate. Kinetic analysis indicated that hexanal had a significantly higher reaction rate (k = 0.09 ± 0.005 1/sec; 23 ± 1.3 ppmv) compared with the branched aldehydes (k = 0.04 ± 0.0036 1/sec; 31 ± 1.6 ppmv for 2-MB and 0.03 ± 0.0051 1/sec; 22 ± 1.3 ppmv for 3-MB). After 3 months of operation, all three compounds reached 100% removal (50 sec residence time, 18–46 ppmv inlet). Media samples withdrawn from the biofilter and observed under scanning electron microscopy analysis indicated microbial growth, suggesting removal of the aldehydes could be attributed to biodegradation.     

Biofiltration kinetics of a gaseous aldehyde mixture using a synthetic matrix

Although aldehydes contribute to ozone and particulate matter formation, there has been little research on the biofiltration of these volatile organic compounds (VOCs), especially as mixtures. Biofiltration degradation kinetics of an aldehyde mixture containing hexanal, 2-methylbutanal (2-MB), and 3-methylbutanal (3-MB) was investigated using a bench-scale, synthetic, media-based biofilter. The adsorption capacity of the synthetic media for a model VOC, 3-methylbutanal, was 10 times that of compost. Periodic residence time distribution analysis (over the course of 1 yr) via a tracer study (84-99% recovery), indicated plug flow without channeling in the synthetic media and lack of compaction in the reactor. Simple first-order and zero-order kinetic models both equally fit the experimental data, yet analysis of the measured rate constants versus fractional conversion suggested an overall first-order model was more appropriate. Kinetic analysis indicated that hexanal had a significantly higher reaction rate (k = 0.09 +/- 0.005 1/sec; 23 +/- 1.3 ppmv) compared with the branched aldehydes (k = 0.04 +/- 0.0036 1/sec; 31 +/- 1.6 ppmv for 2-MB and 0.03 +/- 0.0051 1/sec; 22 +/- 1.3 ppmv for 3-MB). After 3 months of operation, all three compounds reached 100% removal (50 sec residence time, 18-46 ppmv inlet). Media samples withdrawn from the biofilter and observed under scanning electron microscopy analysis indicated microbial growth, suggesting removal of the aldehydes could be attributed to biodegradation.     

Analysis of waste management issues arising from a field study evaluating decontamination of a biological agent from a building

The Bio-response Operational Testing and Evaluation (BOTE) Project was a cross-government effort designed to operationally test and evaluate a response to a biological incident (release of Bacillus anthracis [Ba] spores, the causative agent for anthrax) from initial public health and law enforcement response through environmental remediation. The BOTE Project was designed to address site remediation after the release of a Ba simulant, Bacillus atrophaeus spp. globigii (Bg), within a facility, drawing upon recent advances in the biological sampling and decontamination areas. A key component of response to a biological contamination incident is the proper management of wastes and residues, which is woven throughout all response activities. Waste is generated throughout the response and includes items like sampling media packaging materials, discarded personal protective equipment, items removed from the facility either prior to or following decontamination, aqueous waste streams, and materials generated through the application of decontamination technologies. The amount of residual contaminating agent will impact the available disposal pathways and waste management costs. Waste management is an integral part of the decontamination process and should be included through “Pre-Incident” response planning. Overall, the pH-adjusted bleach decontamination process generated the most waste from the decontamination efforts, and fumigation with chlorine dioxide generated the least waste. A majority of the solid waste generated during pH-adjusted bleach decontamination was the nonporous surfaces that were removed, bagged, decontaminated ex situ, and treated as waste. The waste during the two fumigation rounds of the BOTE Project was associated mainly with sampling activities. Waste management activities may represent a significant contribution to the overall cost of the response/recovery operation. This paper addresses the waste management activities for the BOTE field test.Implications: Management of waste is a critical element of activities dealing with remediation of buildings and outdoor areas following a biological contamination incident. Waste management must be integrated into the overall remediation process, along with sampling, decontamination, resource management, and other important response elements, rather than being a stand-alone activity. The results presented in this paper will provide decision makers and emergency planners at the federal/state/tribal/local level information that can be used to integrate waste management into an overall systems approach to planning and response activities.     

Sampling Airborne Solids in a Duct Following a 90° Bend

Present standardized methods (ASME Power Test Code 27, Western Precipitation Bulletin 50, etc.) of stack sampling usually stress sampling under conditions of steady flow (no variation with time) in order to obtain data representative of the source emissions. On many occasions these standardized methods are applied when the velocity and/or the mass flow rate of pollutants do vary with time, thus impairing the accuracy of the sampling results. In addition, it is difficult to evaluate any inaccuracy of the sampling data. This paper classifies these two source variables into four categories and suggests basic sampling approaches for each type of source condition. Several standardized procedures are evaluated and classified according to the source conditions to which the procedure is applicable. The intent of this paper is to show the most accurate sampling approach for each source condition and thus serve as a guide when planning source sampling programs.     

Evaluating a drinking-water waste by-product as a novel sorbent for arsenic

Arsenic (As) carcinogenicity to humans and other living organisms has promulgated extensive research on As treatment technologies with varying levels of success; generally, the most efficient methods come with a significantly higher cost burden and they usually perform better in removing As(V) than As(III) from solution. In the reported study, a novel sorbent, a waste by-product of the drinking-water treatment process, namely, drinking-water treatment residuals (WTRs) were evaluated for their ability to adsorb both As(V) and As(III). Drinking-WTRs can be obtained free-of-charge from drinking-water treatment plants, and they have been successfully used to reduce soluble phosphorus (P) concentrations in poorly P-sorbing soils. Phosphate and arsenate molecules have the same tetrahedral geometry, and they chemically behave in a similar manner. We hypothesized that the WTRs would be effective sorbents for both As(V) and As(III) species. Two WTRs (one Fe- and one Al-based) were used in batch experiments to optimize the maximum As(V) and As(III) sorption capacities, utilizing the effects of solid:solution ratios and reaction kinetics. Results showed that both WTRs exhibited high affinities for soluble As(V) and As(III), exhibiting Freundlich type adsorption with no obvious plateau after 2-d of reaction (15000 mg kg-1). The Al-WTR was highly effective in removing both As(V) and As(III), although As(III) removal was much slower. The Fe-WTR showed greater affinity for As(III) than for As(V) and reached As(III) sorption capacity levels similar to those obtained with the Al-WTR-As(V) system (15000 mg kg-1). Arsenic sorption kinetics were biphasic, similar to what has been observed with P sorption by the WTRs. Minimal (<3%) desorption of sorbed As(III) and As(V) was observed, using phosphate as the desorbing ligand. Dissolved Fe2+ concentrations measured during As(III) sorption were significantly correlated (r2=0.74, p<0.005) with the amount of As(III) sorbed by the Fe-WTR. Lack of correlation between Fe2+ in solution and sorbed As(V) (r2=0.2) suggests reductive dissolution of the Fe-WTR mediating As(III) sorption. Results show promising potential for the WTRs in irreversibly retaining As(V) and As(III) that should be further tested in field settings.     

Persistent organic pollutant in a fish community of a sub-alpine lake

This study investigated the presence of organochlorine pollutants in abiotic and biotic samples from Lake Como (Italy). DDTs and PCBs were found to be the major contaminants, ranging from 0.04 to 4.25 and from 0.25 to 40.8 μg/g lipid respectively. Evidence of biomagnification according to the trophic role of the investigated organisms was highlighted by means of Stable Isotope Analysis. A Trophic Magnification Factor (TMF) was calculated for the chemicals of interest and the applicability of the method for global use was confirmed. Statistically significant correlation has been found between the calculated trophic level and the concentrations of more lipophilic compounds, while for the less lipophilic (e.g., HCH, 3CBs) the relationship is no statistically significant and the TMF is close to 1.The role of the foraging area in affecting PCB and DDT concentrations within aquatic ecosystems has been highlighted by a Principal Component Analysis (PCA).     

Herbicide losses in runoff events from a field with a low slope: role of a vegetative filter strip

Herbicide runoff and the effects of a narrow vegetative filter strip (VFS) were studied on an arable field in the low-lying plains of the Veneto Region (north-east Italy). Cultivated plots were compared with and without a 6m wide VFS composed of trees, shrubs and grass. Natural and simulated runoff were monitored during 2000 and 2001. Herbicides applied on the field were: metolachlor (2184-2254 g ha(-1)), terbuthylazine (1000-1127 g ha(-1)) and isoproturon (1000 g ha(-1)). The VFS reduced both runoff depth (10.2-91.2%) and herbicide losses (85.7-97.9%) in the monitored rainfall events. Total herbicide loss with runoff was low (0.69-3.98 g ha(-1) without VFS, less than 0.27 g ha(-1) with VFS), but concentrations were sometimes very high, especially of terbuthylazine and isoproturon during the first events after treatment. In these events there was a high probability of exceeding the ecotoxicological endpoint for algae, but the VFS helped to reduce the potential risk. Two VFS effectiveness mechanisms were identified: (i) dilution, and (ii) a "sponge-like" effect, which temporarily trapped chemicals inside the VFS before releasing them.     

Beech foliage as a bioindicator of pollution near a waste incinerator

Since 1971 unshaded leaves from the top of marked beech trees (Fagus sylvatica L.) in the vicinity of a regional waste incinerator have been sampled every year in early September. The unwashed leaf samples were analyzed for the concentration of Cl- and, in some years, for 16 other elements. The operation of the waste incinerator distinctly increased the Cl- concentration in the foliage. When the flue gas filtration did not work properly, several other elements also accumulated (without any obvious dust accumulation). There were no significant correlations between precipitation and concentration of water-soluble elements in foliage samples. This suggested that precipitation was not accelerating foliar leaching so that the bioindication of pollutant accumulation is not restricted in foliage with a well developed cuticula.