Novel materials for environmental remediation of tailing pond waters containing naphthenic acids

A nanofiltration strategy for tailing pond waters (TPWs) that utilizes cyclodextrin (CD)-based polymeric materials as supramolecular sorbents is proposed. Naphthenic acids (NAs) from the Athabasca TPWs are investigated as the target sorbate molecules.The sorption properties of several supramolecular porous materials were characterized using equilibrium sorption isotherms in aqueous solution wherein electrospray ionization mass spectrometry was used to monitor the concentration of NAs in aqueous solution. The characterization of the supramolecular sorbents was performed using ¹³C NMR and IR spectroscopy, while nitrogen porosimetry was used to estimate their surface area and pore structure properties. Independent estimates of surface area were obtained using a chromophore dye adsorption method in aqueous solution.The sorption results for NAs in solution were compared between a commercially available standard; granular activated carbon (GAC) and three types of synthetic materials. The sorption capacities for GAC ranged from 100 to 160 mg NAs/g of material whereas the polymeric materials ranged from 20 to 30 mg NAs/g of material over the experimental conditions investigated. In general, differences in the sorption properties between GAC and the CD-based sorbents were observed and related to differences in the surface areas of the materials and the chemical nature of the sorbents. The CD-based supramolecular materials displayed sorption capacities ranging from 36.2 to 657 m²/g as compared to that for GAC (795 m²/g).     

Degradation of Cellulose Acetate-Based Materials: A Review

Cellulose acetate polymer is used to make a variety of consumer products including textiles, plastic films, and cigarette filters. A review of degradation mechanisms, and the possible approaches to diminish the environmental persistence of these materials, will clarify the current and potential degradation rates of these products after disposal. Various studies have been conducted on the biodegradability of cellulose acetate, but no review has been compiled which includes biological, chemical, and photo chemical degradation mechanisms. Cellulose acetate is prepared by acetylating cellulose, the most abundant natural polymer. Cellulose is readily biodegraded by organisms that utilize cellulase enzymes, but due to the additional acetyl groups cellulose acetate requires the presence of esterases for the first step in biodegradation. Once partial deacetylation has been accomplished either by enzymes, or by partial chemical hydrolysis, the polymer’s cellulose backbone is readily biodegraded. Cellulose acetate is photo chemically degraded by UV wavelengths shorter than 280 nm, but has limited photo degradability in sunlight due to the lack of chromophores for absorbing ultraviolet light. Photo degradability can be significantly enhanced by the addition of titanium dioxide, which is used as a whitening agent in many consumer products. Photo degradation with TiO₂ causes surface pitting, thus increasing a material’s surface area which enhances biodegradation. The combination of both photo and biodegradation allows a synergy that enhances the overall degradation rate. The physical design of a consumer product can also facilitate enhanced degradation rate, since rates are highly influenced by the exposure to environmental conditions. The patent literature contains an abundance of ideas for designing consumer products that are less persistent in the outdoors environment, and this review will include insights into enhanced degradability designs.     

Use of the electrical aerosol detector as an indicator of the surface area of fine particles deposited in the lung

Because of recent concerns about the health effects of ultrafine particles and the indication that particle toxicity is related to surface area, we have been examining techniques for measuring parameters related to the surface area of fine particles, especially in the 0.003- to 0.5-microm size range. In an earlier study, we suggested that the charge attached to particles, as measured by a prototype of the Electrical Aerosol Detector (EAD, TSI Inc., Model 3070), was related to the 1.16 power of the mobility diameter. An inspection of the pattern of particle deposition in the lung as a function of particle size suggested that the EAD measurement might be a useful indicator of the surface area of particles deposited in the lung. In this study, we calculate the particle surface area (micrometer squared) deposited in the lung per cubic centimeter of air inhaled as a function of particle size using atmospheric particle size distributions measured in Minneapolis, MN, and East St. Louis, IL. The correlations of powers of the mobility diameter, Dx, were highest for X = 1.1-1.6 for the deposited surface area and for X = 1.25 with the EAD signal. This overlap suggested a correspondence between the EAD signal and the deposited surface area. The correlation coefficients of the EAD signal and particle surface area deposited in the alveolar and tracheobronchial regions of the lung for three breathing patterns are in the range of Pearson's r = 0.91-0.95 (coefficient of determination, R2 = 0.82-0.90). These statistical relationships suggest that the EAD could serve as a useful indicator of particle surface area deposited in the lung in exposure and epidemiologic studies of the human health effects of atmospheric particles and as a measure of the potential surface area dose for the characterization of occupational environments.     

Toxicity of fipronil and its enantiomers to marine and freshwater non-targets

Fipronil is a phenylpyrazole insecticide used in agricultural and domestic settings for controlling various insect pests in crops, lawns, and residential structures. Fipronil is chiral; however, it is released into the environment as a racemic mixture of two enantiomers. In this study, the acute toxicity of the (S,+) and (R,-) enantiomers and the racemic mixture of fipronil were assessed using Simulium vittatum IS-7 (black fly), Xenopus laevis (African clawed frog), Procambarus clarkii (crayfish), Palaemonetes pugio (grass shrimp), Mercenaria mercenaria (hardshell clam), and Dunaliella tertiolecta (phytoplankton). Results showed that S. vittatum IS-7 was the most sensitive freshwater species to the racemic mixture of fipronil (LC50 = 0.65 microg/L) while P. pugio was the most sensitive marine species (LC50 = 0.32 microg/L). Procambarus clarkii were significantly more sensitive to the (S,+) enantiomer while larval P. pugio were significantly more sensitive to the (R,-) enantiomer. Enantioselective toxicity was not observed in the other organisms tested. Increased mortality and minimal recovery was observed in all species tested for recovery from fipronil exposure. These results indicate that the most toxic isomer of fipronil is organism-specific and that enantioselective toxicity may be more common in crustaceans than in other aquatic organisms.     

Butyltins, trace metals and morphological variables in surf scoter (Melanitta perspicillata) wintering on the south coast of British Columbia, Canada

From 1998 to 2001 we examined spatial and temporal variation in uptake of contaminants by surf scoters (Melanitta perspicillata) in the Georgia Basin region of the Pacific coast of Canada. Samples were collected during late fall and early spring at industrialized and reference locations, carcasses examined, and tissues collected for histology, biomarkers, and contaminant analyses. Scoters from both Vancouver and Victoria harbours had significantly higher hepatic concentrations of summation operatorbutyltins than birds from a reference site. In adult male surf scoters, hepatic summation operatorbutyltins increased over the winter at two sites (p=0.02, n=26), while mercury increased (p=0.03, n=15) and selenium decreased at one site (p=0.001, n=15). Body condition decreased over the winter at both the treatment site, Howe Sound (p<0.0001, n=12), and the reference site, Baynes Sound (p=0.02, n=15). Multiple regression analysis using Akaike's Information Criteria (AIC(C)) showed an association between hepatic butyltin concentrations and overall body condition (p=0.06, r=-0.237).     

Evaluation of vacuum filter sock surface sample collection method for Bacillus spores from porous and non-porous surfaces

Vacuum filter socks were evaluated for recovery efficiency of powdered Bacillus atrophaeus spores from two non-porous surfaces, stainless steel and painted wallboard and two porous surfaces, carpet and bare concrete. Two surface coupons were positioned side-by-side and seeded with aerosolized Bacillus atrophaeus spores. One of the surfaces, a stainless steel reference coupon, was sized to fit into a sample vial for direct spore removal, while the other surface, a sample surface coupon, was sized for a vacuum collection application. Deposited spore material was directly removed from the reference coupon surface and cultured for enumeration of colony forming units (CFU), while deposited spore material was collected from the sample coupon using the vacuum filter sock method, extracted by sonication and cultured for enumeration. Recovery efficiency, which is a measure of overall transfer effectiveness from the surface to culture, was calculated as the number of CFU enumerated from the filter sock sample per unit area relative to the number of CFU enumerated from the co-located reference coupon per unit area. The observed mean filter sock recovery efficiency from stainless steel was 0.29 (SD = 0.14, n = 36), from painted wallboard was 0.25 (SD = 0.15, n = 36), from carpet was 0.28 (SD = 0.13, n = 40) and from bare concrete was 0.19 (SD = 0.14, n = 44). Vacuum filter sock recovery quantitative limits of detection were estimated at 105 CFU m(-2) from stainless steel and carpet, 120 CFU m(-2) from painted wallboard and 160 CFU m(-2) from bare concrete. The method recovery efficiency and limits of detection established in this work provide useful guidance for the planning of incident response environmental sampling for biological agents such as Bacillus anthracis.     

Political transition and emergent forest‐conservation issues in Myanmar

Political and economic transitions have had substantial impacts on forest conservation. Where transitions are underway or anticipated, historical precedent and methods for systematically assessing future trends should be used to anticipate likely threats to forest conservation and design appropriate and prescient policy measures to counteract them. Myanmar is transitioning from an authoritarian, centralized state with a highly regulated economy to a more decentralized and economically liberal democracy and is working to end a long‐running civil war. With these transitions in mind, we used a horizon‐scanning approach to assess the 40 emerging issues most affecting Myanmar's forests, including internal conflict, land‐tenure insecurity, large‐scale agricultural development, demise of state timber enterprises, shortfalls in government revenue and capacity, and opening of new deforestation frontiers with new roads, mines, and hydroelectric dams. Averting these threats will require, for example, overhauling governance models, building capacity, improving infrastructure‐ and energy‐project planning, and reforming land‐tenure and environmental‐protection laws. Although challenges to conservation in Myanmar are daunting, the political transition offers an opportunity for conservationists and researchers to help shape a future that enhances Myanmar's social, economic, and environmental potential while learning and applying lessons from other countries. Our approach and results are relevant to other countries undergoing similar transitions.