Relationships between analytical methods utilized as tools in the evaluation of landfill waste stability

In this study, the refuse from 12 landfills of various ages ranging from fresh refuse to material 11 years old was collected, and changes in the bio-stability parameters were determined. The parameters measured included cellulose, lignin, biochemical methane potential (BMP) and volatile solids, along with plastics. These parameters, along with the cellulose to lignin ratio were compared to determine which were most indicative of the bio-stability of the refuse. Lignin and volatile solids measurements were affected by plastics in refuse samples. Plastics increased both lignin and volatile solids measurements by approximately 10%. Cellulose and volatile solids measurements correlated well with age, each other, and with BMP measurements and were therefore considered the best parameters to determine stability. Data for the Riverbend landfill, a landfill with a moisture content of 48%, which is similar to that of bioreactor landfills, showed that degradation was nearly complete after 5 years as indicated by low values for cellulose and BMP.     

Measurement of Indoor Air Emissions from Dry-Process Photocopy Machines

Abstract

Presently, no standard test method exists to evaluate the various emissions from office equipment (e.g., ozone, volatile organic compounds, inorganic gases, and particulates) so it is difficult to compare data from different studies.1 As a result, the authors are developing a standardized guidance document for measuring indoor air emissions from office equipment. The ultimate goal is to apply the test method to better understand emissions from office equipment and to develop lower emitting machines. This paper provides background information on indoor air emissions from office equipment with an emphasis on dry-process photocopy machines. The test method is described in detail, along with the results of a study to evaluate the test method using four dry-process photocopy machines.

The results from this study indicate that the test method provides acceptable performance for characterizing emissions; that it can adequately identify differences in emissions between machines both in compounds emitted and their emission rates; and that it is capable of measuring both intra- and inter-machine variability in emissions. Challenges and complications were encountered in developing and implementing the test method. These included heat generation, which can cause large increases in chamber temperature; finite paper supplies for photocopy machines, which limit test duration; varying power requirements that may require changes in chamber electrical supply; and remote starting of the machines, which is necessary to maintain chamber integrity.

Results show that dry-process photocopy machines can produce emissions of ozone and volatile organic compounds that can potentially have a significant impact on indoor air quality. For the four machines tested in this study, the compounds with the highest emission rates overall were ethylbenzene (28,000 µg/hour), m,p-xylenes (29,000 µg/hour), o-xylene (17,000 µg/hour), 2-ethyl-lhexanol (14,000 µg/hour), and styrene (12,000 fig/hour). Although many of the same compounds tended to be detected in emissions from each of the four photocopiers, the relative contribution of individual compounds varied considerably between machines, with differences greater than an order of magnitude for some compounds.     

Bioremoval of diethylketone by the synergistic combination of microorganisms and clays: uptake, removal and kinetic studies

The performance of two bacteria, Arthrobacter viscosus and Streptococcus equisimilis, and the effect of the interaction of these bacteria with four different clays on the retention of diethylketone were investigated in batch experiments. The uptake, the removal percentages and the kinetics of the processes were determined. S. equisimilis, by itself, had the best performance in terms of removal percentage, for all the initial diethylketone concentrations tested: 200, 350 and 700 mg/L. The uptake values are similar for both bacteria. A possible mechanism to explain the removal of diethylketone includes its degradation by bacteria, followed by the adsorption of the intermediates/sub-products by the functional groups present on the cells' surfaces. The assays performed with bacteria and clays indicated that the uptake values are similar despite of the clay used, for the same microorganism and mass of clay, but in general, higher values are reached when S. equisimilis is used, compared to A. viscosus. Kinetic data were described by pseudo-first- and pseudo-second-order models.     

Acetylcholinesterase in honey bees (Apis mellifera) exposed to neonicotinoids, atrazine and glyphosate: laboratory and field experiments

In Québec, as observed globally, abnormally high honey bee mortality rates have been reported recently. Several potential contributing factors have been identified, and exposure to pesticides is of increasing concern. In maize fields, foraging bees are exposed to residual concentrations of insecticides such as neonicotinoids used for seed coating. Highly toxic to bees, neonicotinoids are also reported to increase AChE activity in other invertebrates exposed to sub-lethal doses. The purpose of this study was therefore to test if the honey bee’s AChE activity could be altered by neonicotinoid compounds and to explore possible effects of other common products used in maize fields: atrazine and glyphosate. One week prior to pollen shedding, beehives were placed near three different field types: certified organically grown maize, conventionally grown maize or non-cultivated. At the same time, caged bees were exposed to increasing sub-lethal doses of neonicotinoid insecticides (imidacloprid and clothianidin) and herbicides (atrazine and glyphosate) under controlled conditions. While increased AChE activity was found in all fields after 2 weeks of exposure, bees close to conventional maize crops showed values higher than those in both organic maize fields and non-cultivated areas. In caged bees, AChE activity increased in response to neonicotinoids, and a slight decrease was observed by glyphosate. These results are discussed with regard to AChE activity as a potential biomarker of exposure for neonicotinoids.     

Core–shell magnetite-silica dithiocarbamate-derivatised particles achieve the Water Framework Directive quality criteria for mercury in surface waters

The sorption capacity of nanoporous titanosilicate Engelhard titanosilicate number 4 (ETS-4) and silica-coated magnetite particles derivatised with dithiocarbamate groups towards Hg(II) was evaluated and compared in spiked ultra-pure and spiked surface-river water, for different batch factors. In the former, and using a batch factor of 100 m³/kg and an initial Hg(II) concentrations matching the maximum allowed concentration in an effluent discharge, both materials achieve Hg(II) uptake efficiencies in excess of 99 % and a residual metal concentration lower than the guideline value for drinking water quality. For the surface-river water and the same initial concentration, the Hg(II) uptake efficiency of magnetite particles is outstanding, achieving the quality criteria established by the Water Framework Directive (concerning Hg concentration in surface waters) using a batch factor of 50 m³/kg, while the efficiency of ETS-4 is significantly inferior. The dissimilar sorbents’ Hg(II) removal efficiency is attributed to different uptake mechanisms. This study also highlights the importance of assessing the effective capacity of the sorbents under realistic conditions in order to achieve trustable results.     

Black Carbon and Polycyclic Aromatic Hydrocarbon Emissions from Vehicles in the United States–Mexico Border Region: Pilot Study

The investigators developed a system to measure black carbon (BC) and particle-bound polycyclic aromatic hydrocarbon (PAH) emission factors during roadside sampling in four cities along the United States–Mexico border, Calexico/Mexicali and El Paso/Juárez. The measurement system included a photoacoustic analyzer for BC, a photoelectric aerosol sensor for particle-bound PAHs, and a carbon dioxide (CO₂) analyzer. When a vehicle with measurable emissions passed the system probe, corresponding BC, PAH, and CO₂ peaks were evident, and a fuel-based emission factor was estimated. A picture of each vehicle was also recorded with a digital camera. The advantage of this system, compared with other roadside methods, is the direct measurement of particulate matter components and limited interference from roadside dust. The study revealed some interesting trends: Mexican buses and all medium-duty trucks were more frequently identified as high emitters of BC and PAH than heavy-duty trucks or passenger vehicles. In addition, because of the high daily mileage of buses, they are good candidates for additional study. Mexican trucks and buses had higher average emission factors compared with U.S. trucks and buses, but the differences were not statistically significant. Few passenger vehicles had measurable BC and PAH emissions, although the highest emission factor came from an older model passenger vehicle licensed in Baja California.     

PBDE flame retardants and PCBs in migrating Steller sea lions (Eumetopias jubatus) in the Strait of Georgia, British Columbia, Canada

Polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs) were measured in blubber biopsy samples from 22 live-captured Steller sea lions (Eumetopias jubatus) that had just entered the Strait of Georgia, British Columbia, Canada, for their overwintering feeding season. ∑PBDE ranged from 50 μg kg⁻¹ (lipid weight) in adult females to 3780 μg kg⁻¹ in subadult individuals. ∑PCBs ranged from 272 μg kg⁻¹ in adult females to 14 280 μg kg⁻¹ in subadult individuals. While most PBDE and PCB congeners were transferred through milk to pups, PCBs with log K_OW > 7.0 (PCBs 206, 207, 208 and 209) appeared constrained, resulting in a lighter mixture in pups compared to adult females. The ratio of individual PCB congeners by metabolic group (Groups I, II, III, IV and V) to PCB-153 regressed against length of males suggested poor biotransformation of these compounds (slopes did not differ from zero, p > 0.05). PBDE congeners 49, 99, 153 and 183 appeared bioaccumulative (slopes of ratio BDE/PCB 153 versus length were higher than zero, p < 0.05), but the dominance of the single congener, BDE-47 (64% of total PBDEs), likely due in part to debromination pathways, reduced our ability to explore congener-specific dynamics of PBDEs in these pinnipeds. With 80% of our Steller sea lions exceeding a recent toxicity reference value for PCBs, the fasting-associated mobilization of these contaminants raises concerns about a heightened vulnerability to adverse effects during annual migrations.     

Compound specific carbon and hydrogen stable isotope analyses of volatile organic compounds in various emissions of combustion processes

This study presents carbon (δ¹³C) and hydrogen (δD) isotope values of volatile organic compounds (VOCs) in various emission sources using thermal desorption-gas chromatography-isotope ratio mass spectrometry (TD-GC-irMS). The investigated VOCs ranged from C6 to C10. Samples were taken from (i) car exhaust emissions as well as from plant combustion experiments of (ii) various C3 and (iii) various C4 plants. We found significant differences in δ values of analysed VOCs between these sources, e.g. δ¹³C of benzene ranged between (i) −21.7 ± 0.2‰, (ii) −27.6 ± 1.6‰ and (iii) −16.3 ± 2.2‰, respectively and δD of benzene ranged between (i) −73 ± 13‰, (ii) −111 ± 10‰ and (iii) −70 ± 24‰, respectively. Results of VOCs present in investigated emission sources were compared to values from the literature (aluminium refinery emission). All source groups could be clearly distinguished using the dual approach of δ¹³C and δD analysis. The results of this study indicate that the correlation of compound specific carbon and hydrogen isotope analysis provides the potential for future research to trace the fate and to determine the origin of VOCs in the atmosphere using thermal desorption compound specific isotope analysis.     

Limitations of reverse polyethylene samplers (RePES) for evaluating toxicity of field contaminated sediments

Passive samplers are used to measure dissolved nonionic organic contaminants (NOCs) in environmental media. More recently, reverse polyethylene samplers (RePES) have been used with spiked sediments to recreate interstitial water exposure concentrations and observed toxicity. In the present study, RePES were used with field contaminated sediments. The RePES was not capable of recreating the pattern of toxicity with the amphipod and mysid observed with intact field sediments. Decreased survival in the RePES exposures as compared to the whole sediment exposures was most likely caused by an overexposure to NOCs due to a lack of surrogate black carbon in the RePES system. As an alternative, aqueous phase studies were performed in which polyethylene was allowed to equilibrate with slurries of intact sediments for 3 weeks. Three weeks was found to be an insufficient amount of time for the polyethylene to equilibrate with the sediment. An additional study demonstrated 3 months was sufficient for lower contaminant concentrations, but might not be an adequate amount of time for more highly contaminated sediments. The aqueous phase transfer approach may be useful if equilibration is sufficiently long, although this length of time may be impractical for use in certain applications, such as toxicity identification evaluations (TIEs).     

The use of oxygen consumption and ammonium excretion to evaluate the toxicity of cadmium on Farfantepenaeus paulensis with respect to salinity

The main purpose of the present study was to detect the acute toxicity of cadmium (Cd) in F. paulensis and to investigate its effect on oxygen consumption and ammonium excretion different salinities. First, we examined the acute toxicity of Cd in F. paulensis at 24, 48, 72, and 96-h lethal concentration (LC50). Cd was significantly more toxic at 5 salinity than at 20 and 36. The oxygen consumption and ammonium excretion were estimated through experiments performed on each of the twelve possible combinations of three salinities (36, 20 and 5), at temperature 20 °C. Cd showed a reduction in oxygen consumption at 5 salinity, the results show that the oxygen consumption decreases with respect to the Cd concentration. At the highest Cd concentration employed (2 mg L⁻¹), the salinity 5 and the temperature at 20 °C, oxygen consumption decreases 53.7% in relation to the control. In addition, after separate exposure to Cd, elevation in ammonium excretion was obtained, wish were 72%, 65% and 95% higher than the control, respectively. The results show that Cd is more toxic to F. paulensis at lower salinities.