1,4‐Dioxane: Emerging technologies for an emerging contaminant

The synthetic chemical, 1,4‐dioxane, is classified by the U.S. Environmental Protection Agency (EPA) as a probable human carcinogen. Between 2013 and 2015, the EPA detected 1,4‐dioxane in public drinking water supplies in 45 states at concentrations up to 33 µg/L and in groundwater from releases at hazardous waste sites across the United States. Although a Federal maximum contaminant level drinking water standard has not yet been proposed, state‐specific standards and criteria are as low as 0.3 µg/L. 1,4‐Dioxane is a recalcitrant chemical in that applications of conventional treatment technologies have had limited success in reducing concentrations in water to meet current and proposed health‐protective levels. Although mainly used as a stabilizer for the solvent 1,1,1‐trichloroethane, it has been used in other industrial processes and has been detected in a variety of consumer products, such as foods, pharmaceuticals, cosmetics, and detergents. The high aqueous solubility of 1,4‐dioxane coupled with limited solubility of chlorinated solvents typically found in conjunction with 1,4‐dioxane contamination is the primary reason for its treatment challenges. In the last several years, an alternative, cost‐effective technology has been developed that has demonstrated treatment to levels significantly lower than the Federal and state‐specific goals. This article provides a Federal and state‐by‐state summary of 1,4‐dioxane‐specific drinking water and groundwater concentration criteria and qualitative comparison of the effectiveness of conventional treatment technologies compared to the effectiveness of an alternative treatment technology. A case study is also provided to present details regarding the application of an alternative treatment technology at an active groundwater remediation site in California.     

Evaluation of PFAS treatment technology: Alkaline ozonation

A bench‐scale treatability study was performed to evaluate the effectiveness of alkaline ozonation on removing per‐ and polyfluoroalkyl substances (PFAS) present in groundwater at a former industrial site in Michigan. The study involved testing the PFAS‐impacted groundwater under alkaline ozonating conditions under a range of experimental conditions, including modifying pH, hydrogen peroxide‐to‐ozone molar ratio doses, length of ozonation pretreatment times, and sampling techniques. PFAS‐spiked samples were used to determine if inorganic ions such as fluoride (F^?), sulfate (SO₄^2?), formate (HCOO^?), acetate (CH₃COO^?), and trifluoroacetate (CF₃COO^?) were generated or if there were decreases in total organic fluorine resulting from PFAS treatment. The results from all tests indicate that decreases in PFAS concentrations were due to a combination of removal and destructive mechanisms with enhanced removal under acidic pH ozonation pretreatment conditions. Short‐chain PFAS concentrations increased during the experiments followed by an overall decrease in concentration under continuous alkaline ozonation conditions. Reductions in concentrations in perfluorooctane sulfonic acid of 75–97% were observed. Reductions in concentrations were also observed in other PFAS such as 6:2 FTS, PFHxS, PFOA, and PFNA. To our best knowledge, this is the first time that alkaline ozonation has been performed on PFAS‐impacted water while monitoring a larger suite of PFAS analytes in addition to destruction byproducts. Treatment of PFAS under the conditions discussed in this paper suggests that alkaline ozonation may be a viable remediation option for PFAS‐impacted waters.     

Modeling oil dispersion under breaking waves. Part II: Coupling Lagrangian particle tracking with population balance model

Environmental Fluid Mechanics - Oil dispersion under a deep-water plunging breaker of height 0.15 m was studied by coupling the Lagrangian particle tracking code (NEMO3D) with the...     

Keeping pace with forestry: Multi-scale conservation in a changing production forest matrix

The multi-scale approach to conserving forest biodiversity has been used in Sweden since the 1980s, a period defined by increased reserve area and conservation actions within production forests. However, two thousand forest-associated species remain on Sweden’s red-list, and Sweden’s 2020 goals for sustainable forests are not being met. We argue that ongoing changes in the production forest matrix require more consideration, and that multi-scale conservation must be adapted to, and integrated with, production forest development. To make this case, we summarize trends in habitat provision by Sweden’s protected and production forests, and the variety of ways silviculture can affect biodiversity. We discuss how different forestry trajectories affect the type and extent of conservation approaches needed to secure biodiversity, and suggest leverage points for aiding the adoption of diversified silviculture. Sweden’s long-term experience with multi-scale conservation and intensive forestry provides insights for other countries trying to conserve species within production landscapes.

     

PVC and PET microplastics in caddisfly (Lepidostoma basale) cases reduce case stability

Environmental Science and Pollution Research - Caddisfly larvae occur in streams and rivers, and many caddisfly species build protective cases using material from their habitat such as sand grains....     

Spatial and temporal drivers of zoonotic pathogen contamination of an agricultural watershed

In regions where animal agriculture is prominent, such as southern Alberta, higher rates of gastrointestinal illness have been reported when compared with nonagricultural regions. This difference in the rate of illness is thought to be a result of increased zoonotic pathogen exposure through environmental sources such as water. In this study, temporal and spatial factors associated with bacterial pathogen contamination of the Oldman River, which transverses this region, were analyzed using classification and regression tree analysis. Significantly higher levels of fecal indicators; more frequent isolations of Campylobacter spp., Escherichia coli O157:H7, and Salmonella enterica spp.; and higher rates of detection of pig-specific Bacteroides markers occurred at downstream sites than at upstream sites, suggesting additive stream inputs. Fecal indicator densities were also significantly higher when any one of these three bacterial pathogens was present and where there were higher total animal manure units; however, occasionally pathogens were present when fecal indicator levels were low or undetectable. Overall, Salmonella spp., Campylobacter spp., and E. coli O157:H7 presence was associated with season, animal manure units, and total rainfall on the day of sampling and 3 d in advance of sampling. Several of the environmental variables analyzed in this study appear to influence pathogen prevalence and therefore may be useful in predicting water quality and safety and in the improvement of watershed management practices in this and other agricultural regions.     

Communicating climate science: The role of perceived communicator’s motives

In two experimental studies, we investigated the effects of public perceptions of climate scientists’ communicative motives on trust in scientists and willingness to engage with climate science messages. Study 1 demonstrated that members of the public who were led to believe that scientists aim to inform about the consequences of climate change (rather than to persuade to take a particular course of action) reported higher trust in scientists and stronger willingness to engage in environmental behaviour. Study 2 revealed that this effect was moderated by the style of the scientific message that participants were exposed to. Participants who expected scientists to engage in persuasion were more receptive to persuasive rather than informative messages, while the opposite was true for participants who believed that scientists’ purpose was purely to inform. In both studies the effects of perceived motives on willingness to act in line with the climate change messages were mediated through trust in scientists. The data demonstrate that managing public expectations about the purposes of science communication and delivering messages that are consistent with these expectations are a key to successful communication of climate science.     

Conversion of nitrogen oxides on commercial photocatalytic dispersion paints

In the present study, photocatalytic reactions of nitrogen oxides (NO_x = NO + NO₂) were studied on commercial TiO₂ doped facade paints in a flow tube photoreactor under simulated atmospheric conditions. Fast photocatalytic conversion of NO and NO₂ was observed only for the photocatalytic paints and not for non-catalytic reference paints. Nitrous acid (HONO) was formed in the dark on all paints studied, however, it efficiently decomposes under irradiation only on the photocatalytic samples. Thus, it is concluded that photocatalytic paint surfaces do not represent a daytime source of HONO, in contrast to other recent studies on pure TiO₂ surfaces. As main final product, the formation of adsorbed nitric acid/nitrate anion (HNO₃/NO₃^?) was observed with near to unity yield. In addition, traces of H₂O₂ were observed in the gas phase only in the presence of O₂. Formation of the greenhouse gas nitrous oxide (N₂O) could be excluded. The uptake kinetics of NO, NO₂ and HONO was very fast under atmospheric conditions (e.g. γ(NO + TiO₂) > 10^?5). Thus, the uptake on urban surfaces (painted houses, etc.) will be limited by transport. For a hypothetically painted street canyon, an average reduction of nitrogen oxide levels of ca. 5% is estimated. Since the harmful HNO₃/NO₃^? is formed on the surface of the photoactive paints, whereas it is formed in the gas phase in the atmosphere, the use of photocatalytic paints may also help to reduce acid deposition, e.g. on plants, or nitric acid related health issues.     

Occupational embeddedness and job performance

While researchers have recently focused their attention on organizational embeddedness, occupational embeddedness has received little theoretical and empirical attention. Using multisource data on 162 employees in multiple jobs and organizations, we found that occupational embeddedness is positively related to both task performance and creativity and is negatively related to counterproductive work behavior, even after controlling for the effects of organizational embeddedness. In addition, we found that trait affect moderated the relationships of occupational embeddedness to job performance. Occupational embeddedness was more strongly related to counterproductive work behavior when trait negative affect was high, while occupational embeddedness was more strongly related to both citizenship behavior and creativity when trait positive affect was high. Results also indicated that the various components of occupational embeddedness had different effects on job outcomes. Fit had a strong positive effect on core task performance, links had a positive effect on creativity, and sacrifice had a small positive effect on citizenship behavior. The article concludes with a discussion of implications for future research and management practice. Copyright © 2009 John Wiley & Sons, Ltd.     

Dust explosions: How should the influence of humidity be taken into account?

In this work, the influence of humidity on dust explosions of metallic (aluminium) and organic materials (icing sugar, polyethylene and magnesium stearate) has been studied. The impact of pre-humidification of powders on their ignition sensitivity, their volume resistivity and charge decay time has been assessed. The influence of humidity on explosion severity has also been studied by two methods: on the one hand, the dust sample was stored in a controlled workstation at constant relative humidity; on the other hand, the dry dust was dispersed in a humidity controlled atmosphere in the vessel.As expected, the effect of humidity strongly depends on the chemical nature of the particles. Experiments on powders volume resistivity and charge decay time have shown typical trends but have especially pointed out the inadequacy of some standards. Inhibition phenomena have been verified for polyethylene and magnesium stearate, whereas both inhibition and promotion have been observed for icing sugar and could be explained by an evolution of sucrose structure. Dry aluminium dust explosions in humid atmosphere show that water vapour inerts the explosion. However, when aluminium is stored at controlled humidity, the maximum rise of pressure rate increases with the water content, which is probably due to hydrogen generation.