Sustainable Water Purification and Energy Generation Over Crystalline Chitosan Grafted Polyaniline Composite

Journal of Polymers and the Environment - The present research demonstrates the design and development of a dual-compartment water purification proto-plant for microbial degradation of organic...     

The role of negative affectivity in the stress process: Tests of alternative models

The prominence of the personality trait of Negative Affectivity (NA) in the stress literature has increased over the last decade. Negative affectivity has been widely reported both to have direct effects on measures of strain, and to act as a potential confounding variable of stressor–strain relations in self-report research (Watson and Clark, 1984). However, more recent work has demonstrated that NA can also moderate environment–outcome relationships, acting as a vulnerability factor in the stress model, or alternatively that its influence may be mediated through perceptions of the work environment. In the present study, these four possible pathways through which NA may be implicated in job satisfaction and symptom report were examined. In terms of symptom report, NA was found to have direct effects, to act as a partial confound, and to play a significant moderating (vulnerability) role. In contrast, for the prediction of job satisfaction, the influence of NA was found to be mediated through perceptions of the work environment. It is concluded that all these potential roles of NA should be more thoroughly considered in future stress research.     

Policy support for rural economic development based on Holling’s ecological concept of panarchy

Globally, rural regions are searching for innovative growth opportunities to reinvigorate their economies. This paper examines the redevelopment of rural communities through an ecological lens – based on the notion of continuous cycles of adaptive change within complex systems as first identified within Holling’s concept of panarchy. Panarchy suggests that complex systems have more than a single equilibrium point and, instead, have some inherent resiliency based on the notion of multiple stable regimes. As such, panarchy provides a conceptual model that describes the ways in which complex social and ecological systems are organized and structured both spatially and temporally. By drawing parallels between the characteristics of ecological communities and rural economic systems, a novel framework is developed to assist policy-makers reflect on a rural community’s position along its own adaptive change cycle and, then, implement appropriate inventions to improve system resiliency – which in this case is linked with economic resiliency through development and/or growth. Supported by empirical data emerging from both key informant interviews and content analysis of current rural development policy, this work also identifies leverage points where policy intervention may be most advantageous by specifying the timing of policy instruments on the cycle. Specifically, this framework describes four leverage points, three major and one minor, to help push or pull rural regions into an area of higher resilience.     

Quantifying chlorinated ethene degradation during reductive dechlorination at Kelly AFB using stable carbon isotopes

Stable isotope analysis of chlorinated ethene contaminants was carried out during a bioaugmentation pilot test at Kelly Air Force Base (AFB) in San Antonio Texas. In this pilot test, cis-1,2-dichloroethene (cDCE) was the primary volatile organic compound. A mixed microbial enrichment culture, KB-1, shown in laboratory experiments to reduce chlorinated ethenes to non-toxic ethene, was added to the pilot test area. Following bioaugmentation with KB-1, perchloroethene (PCE), trichloroethene (TCE) and cDCE concentrations declined, while vinyl chloride (VC) concentrations increased and subsequently decreased as ethene became the dominant transformation product. Shifts in carbon isotopic values up to 2.7 per thousand, 6.4 per thousand, 10.9 per thousand and 10.6 per thousand were observed for PCE, TCE, cDCE and VC, respectively, after bioaugmentation, consistent with the effects of biodegradation. While a rising trend of VC concentrations and the first appearance of ethene were indicative of biodegradation by 72 days post-bioaugmentation, the most compelling evidence of biodegradation was the substantial carbon isotope enrichment (2.0 per thousand to 5.0 per thousand) in ?13C(cDCE). Fractionation factors obtained in previous laboratory studies were used with isotope field measurements to estimate first-order cDCE degradation rate constants of 0.12 h(-1) and 0.17 h(-1) at 115 days post-bioaugmentation. These isotope-derived rate constants were clearly lower than, but within a factor of 2-4 of the previously published rate constant calculated in a parallel study at Kelly AFB using chlorinated ethene concentrations. Stable carbon isotopes can provide not only a sensitive means for early identification of the effects of biodegradation, but an additional means to quantify the rates of biodegradation in the field.     

A rapidly equilibrating, thin film, passive water sampler for organic contaminants; characterization and field testing

Improving methods for assessing the spatial and temporal resolution of organic compound concentrations in marine environments is important to the sustainable management of our coastal systems. Here we evaluate the use of ethylene vinyl acetate (EVA) as a candidate polymer for thin-film passive sampling in waters of marine environments. Log K_EVA−W partition coefficients correlate well (r² = 0.87) with Log K_OW values for selected pesticides and polychlorinated biphenyls (PCBs) where Log K_EVA−W = 1.04 Log K_OW + 0.22. EVA is a suitable polymer for passive sampling due to both its high affinity for organic compounds and its ease of coating at sub-micron film thicknesses on various substrates. Twelve-day field deployments were effective in detecting target compounds with good precision making EVA a potential multi-media fugacity meter.     

Sediment: curse or blessing for Tonle Sap Lake?

It has been claimed that Tonle Sap Lake is rapidly filling with sediment as a result of increasing sediment yields from the catchment. Infilling of the lake basin would have serious implications for the magnitude of flooding in central Cambodia and the Mekong Delta region and threaten the lake's unique ecosystem. In this article, we synthesize the results of radiocarbon dating of sediment cores and hydrodynamic modeling results to provide an empirically based assessment of this issue. We find that current sedimentation rates within the lake basin proper are low and have been for several millennia. However, sedimentation at the lake margin and in its floodplain is relatively high, which presents a range of issues for riparian communities.     

Dicamba and 2,4-D residues following applicator cleanout: A potential point source to the environment and worker exposure

This paper presents a survey of pesticide residues in tanks following application and throughout the cleanout procedure as conducted by 46 volunteer operators across Colorado. While many pesticides were detected, this paper focuses on dicamba and 2,4-D, which were detected by liquid chromatography/tandem mass spectroscopy (LC-MS/MS). An exponential decrease in concentration was observed with sequential rinses, although this decrease may be more rapid for more water-soluble pesticides. More than 95% of the pesticide in the prerinse solution was removed by the end of the third rinse in all but three operator samples. Concentrations after three rinses were 0.41 ± 0.25 and 3.3 ± 1.1 mg/L for dicamba and 2,4-D, respectively. These concentrations suggest that the recommended practice of three rinses may not be adequate to eliminate off-target effects or point sources of pesticide waste, and that the recommended standard of personal protective equipment is essential to prevent worker exposure to the chemicals.

Implications:?This paper demonstrates that the waste generated during cleanout of pesticide application devices constitutes a potential source of pollution and worker exposure. In particular, while the first rinse of pesticide containers is often treated as hazardous waste and reapplied to crops, the remaining rinses are not. This work demonstrates that the wastewater generated in subsequent rinses can have high enough concentrations to impact worker health, cause off-target effects on crops, and potentially constitute a point source of pesticides. The practical implication is for improved recommendations and regulations regarding pesticide applicators and their cleanout process.