Zero valent iron remediation of a mixed brominated ethene contaminated groundwater

The suitability of a granulated zero valent iron (ZVI) permeable reactive barrier (PRB) remediation strategy was investigated for tribromoethene (TriBE), cis-1,2-dibromoethene (c-DBE), trans-1,2-dibromoethene (t-DBE) and vinyl bromide (VB), via batch and large-scale column experiments that were subsequently analysed by reactive transport modelling.The brominated ethenes in both batch and large-scale column experiments showed rapid (compared to controls and natural attenuation) degradation in the presence of ZVI. In the large-scale column experiment, degradation half-lives were 0.35 days for TriBE, 0.50 days for c-DBE, 0.31 days for t-DBE and 0.40 days for VB, under site groundwater flow conditions, resulting in removal of brominated ethenes within the first 0.2 m of a 1.0 m thick ZVI layer, indicating that a PRB groundwater remediation strategy using ZVI could be used successfully.In the model simulations of the ZVI induced brominated ethene degradation, assuming a dominant reductive β-elimination pathway via bromoacetylene and acetylene production, simulated organic compound concentrations corresponded well with both batch and large-scale column experimental data. Changes of inorganic reactants were also well captured by the simulations. The similar ZVI induced degradation pathway of TriBE and TCE suggests that outcomes from research on ZVI induced TCE remediation could also be applied to TriBE remediation.     

Programmable Instrument for Controlling Atmospheric Sampling

The University of Arizona and the Pima County Air Pollution Control District conducted a comparison study of the following aerosol samplers: a standard high-volume sampler, a high-volume sampler fitted with a size selective inlet, and a dichotomous virtual impactor. Over sixty samples were collected with the colocated samplers during the first six months of 1981. The concentration (μg/m³) of suspended particulate matter and of sulfate was determined for all the samples, while the concentration of four lithophilic elements (Ca, Fe, Mg, and K) was determined on one third of the samples. Well-defined linear relationships for suspended particulate matter and sulfate were found to exist between each of the three sample collection methods over the concentrafion range encountered in this study. For these samples, there were significant differences in the particulate mass and large particle lithophilic element concentrations collected by each device. However, sulfate values obtained from the three samplers were in excellent agreement with each other. This suggests that the inlet collection efficiency for large particles differs significantly for these three sampling devices. Since the size selective inlet and the dichotomous virtual impactor samplers are each designed for collection of inhalable particles (particles of 15 μm aerodynamic diameter and smaller), they would have been expected to measure approximately equivalent particle mass concentrations. Thus, these differences are important to those interested in selecting a method for measuring airborne particle mass concentrations.     

Paleoecological Assessment of Watershed History in PRIMENet Watersheds at Acadia National Park, USA

Paleoecological reconstructions of forest stand histories for two upland watersheds at Acadia National Park in Maine were completed to support related watershed chemistry studies. The project hypothesis was that forest type and fire history influence long-term cycling and storage of atmospheric mercury and nitrogen within watersheds. The reconstructions document differences in major vegetation composition and disturbance between the burned and unburned watersheds during the past several centuries. Pollen and charcoal stratigraphies from organic sediment accumulations in forested wet depressions indicate that the present experimental design of contrasting disturbance and forest histories has persisted during recent centuries. The unburned watershed has been dominated by spruce (Picea rubens) and fir (Abies balsamea) for 500 years or more and has not recently burned or been substantially cleared. The burned watershed is dominated by a heterogeneous forest of patchy hardwood, mixed wood, and softwood stands. A large portion of this watershed burned severely in 1947 and probably more than once in the 1800s, and has supported heterogeneous successional forests for 200 years or longer. Overall, these results support the underlying premise that the experimental design of this watershed research can be used to infer landscape controls on biogeochemical processes.     

Adaptive environmental management of tourism in the Province of Siena, Italy using the ecological footprint

Adaptive management as applied to tourism policy treats management policies as experiments that probe the responses of the system as human behavior changes. We present a conceptual systems model that incorporates the gap between observed and desired levels of the ecological footprint with respect to biocapacity. Addressing this gap (or 'overshoot') can inform strategies to increase or decrease visitation or its associated consumption in the coming years. The feedback mechanism in this conceptual model incorporates a gap between observed and desired ecological footprint levels of tourists and residents. The work is based on longer-term and ongoing study of tourism impacts and ecological footprint assessments from the SPIN-Eco Project. We present historical tourism and environmental data from the province of Siena, Italy and discuss the use of discrete, static environmental indicators as part of an iterative feedback process to manage tourism within biophysical limits. We discuss a necessary shift of emphasis from certain and static numbers to a process-based management model that can reflect slow changes to biophysical resources. As underscored by ecological footprint analysis, the energy and material use associated with tourism and local activity can erode natural capital foundations if that use exceeds the area's biological capacity to support it. The dynamic, and iterative process of using such indicators as management feedback allows us to view sustainability more accurately as a transition and journey, rather than a static destination to which management must arrive.     

Characterization of PM2.5-bound polycyclic aromatic hydrocarbons in Atlanta

Twenty-four hour PM_2.5 samples from a rural site, an urban site, and a suburban site (next to a major highway) in the metropolitan Atlanta area in December 2003 and June 2004 were analyzed for 19 polycyclic aromatic hydrocarbons (PAH). Extraction of the air samples was conducted using an accelerated solvent extraction method followed by isotope dilution gas chromatography/mass spectrometry determination. Distinct seasonal variations were observed in total PAH concentration (i.e. significantly higher concentrations in December than in June). Mean concentrations for total particulate PAHs in December were 3.16, 4.13, and 3.40 ng m^?3 for the urban, suburban and rural sites, respectively, compared with 0.60, 0.74, and 0.24 ng m^?3 in June. Overall, the suburban site, which is impacted by a nearby major highway, had higher PAH concentration than did the urban site. Total PAH concentrations were found to be well correlated with PM_2.5, organic carbon (OC), and elemental carbon (EC) in both months (r² = 0.36–0.78, p < 0.05), although the slopes from the two months were different. PAHs represented on average 0.006% of total PM_2.5 mass and 0.017% of OC in June, compared with 0.033% of total PM_2.5 and 0.14% of OC in December. Total PAH concentrations were also correlated with potassium ion (r² = 0.39, p = 0.014) in December, but not in June, suggesting that in winter biomass burning can potentially be an important source for particulate PAH. Retene was found at a higher median air concentration at the rural site than at the urban and suburban sites—unlike the rest of the PAHs, which were found at lower levels at the rural site. Retene also had a larger seasonal difference and had the weakest correlation with the rest of the PAHs measured, suggesting that retene, in particular, might be associated with biomass burning.     

Analysing institutional change in environmental governance: exploring the concept of ‘institutional work’

Institutional work focuses on the role of actors in creating, maintaining, or disrupting institutional structures. The concept has its origin in organisational studies. In this paper, we rethink and redefine institutional work to make it fit for use in the multi-actor and multi-level context of environmental governance. We survey key approaches to institutional change in the literature, and argue that institutional work should have a central place within this theorising. Drawing on the insights from this literature, we argue that studying institutional work should involve a look at both the actions taken by actors, as well as the resulting effects. We identify a critical need for attention to the fundamentally political character of institutional work, the cumulative effects of action taken by multiple actors, and communicative and discursive dimensions. Overall, the concept of institutional work opens up new possibilities for unpacking the longstanding challenge of understanding institutional change in environmental governance.     

Institutional innovation in urban governance: The case of climate change adaptation

Urban governance systems need to be adaptive to deal with emerging uncertainties and pressures, including those related to climate change. Realising adaptive urban governance systems requires attention to institutions, and in particular, processes of institutional innovation. Interestingly, understanding of how institutional innovation and change occurs remains a key conceptual weakness in urban climate change governance. This paper explores how institutional innovation in urban climate change governance can be conceptualised and analysed. We develop a heuristic involving three levels: (1) “visible” changes in institutional arrangements, (2) changes in underlying “rules-in-use”, and (3) the relationship to broader “governance dilemmas”. We then explore the utility of this heuristic through an exploratory case study of urban water governance in Santiago, Chile. The approach presented opens up novel possibilities for studying institutional innovation and evaluating changes in governance systems. The paper contributes to debates on innovation and its effects in urban governance, particularly under climate change.     

DNA confirmation of congenital myotonic dystrophy in non-immune hydrops fetalis

We report on the prenatal diagnosis of congenital myotonic dystrophy in a case of nonimmune hydrops fetalis. DNA analysis of amniocytes revealed expansion of the trinucleotide (CTG) repeat within the myotonin PK gene, associated with myotonic dystrophy. The fetus was found to have approximately 1730 copies, while the normal population has between 5 and 27 copies, and minimally affected individuals have at least 50 copies.     

Instrument tuning for trace analysis of dioxins and furans for the vg 70s/se gas chromatography/mass spectrometry system using electron impact mode

We present the salient characteristics of tuning procedures that have evolved from our 3 years of experience while producing large amounts of data of the highest quality. Our laboratory routinely analyzes 2,3,7,8‐substituted dioxins and furans at parts per quadrillion levels in 50–100 g of human serum samples using the VG 70S/SE stand‐alone gas chromatography/mass spectrometry (GC/MS) system at 10000 resolution (defined by 5% overlap) in the selected ion recording mode. Trace measurement of dioxins and furans in human biological matrices—for example, whole blood, serum, or adipose tissue‐requires reproducible instrument tuning within day as well as among days for quality results. Additionally, instument‐tuning procedures among operators must be reproducible to minimize operator bias because periodically different operators are used. Instrument tuning is highly subjective and argumentive; therefore, to minimize the ambiguity within our laboratory, we have standardized our technique to reproducibly tune the GC/MS system.     

Trends in the Extremes of Sulfur Concentration Distributions

ABSTRACT

Understanding the response of air quality parameters such as visibility to the implementation of new air quality regulations, population growth and redistribution, and federal land managing practices is essential to the evaluation of air quality management plans on air quality in federal Class I areas. For instance, the reduction of SO₂ emissions from large single point sources should result in the decrease of extreme sulfate concentrations, while population growth in geographic areas outside of urban centers could cause a slow widespread increase of sulfate and organic concentrations. The change in federal land managing practice of increased prescribed fire on a year-round basis in lieu of large naturally occurring wild fires could have the same effect; that is, the frequency of high sulfur days increase and low sulfur days decrease as the result of the management practice. Therefore, it is of interest to examine the trends associated with the proportion of days during which the concentration of some aerosol species is above or below a certain threshold and decide whether this proportion of days is increasing or decreasing or shows a lack of trend. This is a direct indication of whether the quality of the environment is improving or worsening, or neither.