The perceived risk of the Line 5 Pipeline and spills under ice

Using the psychometric paradigm of risk in conjunction with surveys of the Michigan public (n = 638) and a regional planning organization (n = 65), we examine the perceived risk and concerns associated with underwater oil pipelines, the Enbridge Line 5 pipeline in particular, and oil spills under ice. The fate of Line 5 is heavily debated in Michigan, specifically the portion that traverses the Straits of Mackinac, which can be ice-covered for months. Scant literature examines how individuals perceive the risk associated with Line 5, its alternatives, or potential spills in open water or under ice. Here we identify considerable concern regarding both the pipeline and the potential for spills under ice on behalf of the public, and increased concern about spills under ice on behalf of the planning organization. Organization members' concerns are significantly predicted by beliefs about the difficulty in remediating spills, however not by beliefs about spills' likelihood, difficulty in detection, noticeability, or consequences. Our results identify the need to better examine and communicate the risks associated with underwater pipelines and spills, both in open water and under ice, as well as options for remediating oil captured under ice. Furthermore, we recommend the adoption of decision-making and risk governance processes that explicitly expand analysis of the social, economic and environmental tradeoffs of underwater pipelines such as Line 5.     

A new approach to evaluating the toxicity and genotoxicity of disinfected drinking water

The aim of this study was to evaluate the formation of toxic and genotoxic compounds in surface drinking waters treated with two widely used disinfectants, sodium hypochlorite (NaClO) and chlorine dioxide (ClO(2)), and a new disinfectant, peracetic acid (PAA). For this purpose a pilot plant was set up to add these biocides continuously to pre-filtered lake water flowing into three different basins. During three seasonal experiments, short-term in vivo tests (with plant, fish and molluscs) and in vitro tests (with bacteria, yeast and human cells) were carried out to evaluate the formation of genotoxic disinfection by-products (DBPs). Gas chromatography/mass spectrometry (GC/MS) was used to identify DBPs produced during the different treatments, microbiological analyses were performed to test the biocidal activity of the disinfectants, and chemical analyses were carried out to evaluate the quality of the water. The pilot drinking water plant under study was useful in studying the toxicity and genotoxicity of disinfected drinking water with this combined chemical/biotoxicological approach. This paper describes the setting up of the pilot plant and sets out/reports the results of the microbiological and chemical analyses.     

Mercury levels in lichens from different host trees around a chlor-alkali plant in New Brunswick,Canada

Mercury concentrations were determined in the epiphytic lichen Hypogymnia physodes along five transects starting from a chlor-alkali plant located at Dalhousie, New Brunswick, a landfill site and a nearby electricity generating station. Lichen samples were collected from white birch (Betula papyrifera) and spruce (Picea sp.) or balsam fir (Abies balsamea). Average lichen background mercury values were 0.088+/-0.005 microg/g from white birch and 0.148+/-0.046 microg/g from spruce trees, with a detection limit of 0.05 microg/g. The chlor-alkali plant and a power plant were identified, respectively, as a major source and a minor source of elevated mercury levels in lichens. At 125 m north-west of the New Brunswick Power plant, 0.28 microg/g Hg were found in Hypogymnia physodes from spruce trees, while at 250 m west (downwind) of the chlor-alkali plant, 3.66 microg/g of mercury were determined. High values, 0.98 microg/g in lichens from spruce trees and 0.79 microg/g in lichen samples from white birch were also measured at 125 m south of the chlor-alkali plant and decreased exponentially with distance. The sphere of influence of the chlor-alkali plant with respect to mercury deposition was estimated to extend 2.4-3.4 km from the plant. The mercury concentrations in Hypogymnia physodes collected from white birch were significantly lower than the concentrations in the same lichen from spruce trees in areas with elevated levels of mercury, but not in areas with low mercury levels. The magnitude of this difference dropped with distance from the source.     

Lethal and sublethal exposure and recovery effects of ozone-produced oxidants on adult white perch (Morone americana Gmelin)

Adult white perch (Morone americana), acclimated to 15°C, were exposed to a series of ozone-produced oxidant (OPO) concentrations for 96 h using continuous flow bioassay techniques. Toxicity data were analyzed using both response surface modeling and standard probit regression. White perch were also exposed to a series of near and sublethal OPO concentrations, selected from the acute toxicity study, for 96 h and then placed in clean non-ozonated water for 14 days. Blood pH, hematocrit and gill histopathology were analyzed during exposure at 24, 48 and 96 h and after 4 and 14 days in the recovery period. Blood pH and hematocrit levels were analyzed statistically using standard ANOVA and multiple range tests. Histopathological effects were examined using both light microscopy and scanning electron microscopy. The 24-, 48- and 96-h LC₃₀'s were 0.38, 0.26 and 0.20 mg OPO l⁻¹, respectively. Blood pH was significantly reduced at concentrations 0.15 mg OPO l⁻¹ but not at 0.10 mg l⁻¹ or lower concentrations. Hematocrit significantly increased at concentrations 0.10 mg OPO l⁻¹. Histopathological examination revealed minimal effects on gill tissue at 0.01 mg OPO l⁻¹, moderate epithelial sloughing and heavy mucus production at 0.05 mg OPO l⁻¹ and extreme tissue damage at concentrations 0.10 mg l⁻¹. Results from both the acute toxicity and the exposure and recovery study were compared with the effects of chlorine-produced oxidants (CPO) obtained from the literature. Both OPO and CPO appear to have similar effects on adult white perch.     

Evolutionary events in a mathematical sciences research collaboration network

This study examines long-term trends and shifting behavior in the collaboration network of mathematics literature, using a subset of data from Mathematical Reviews spanning 1985–2009. Rather than modeling the network cumulatively, this study traces the evolution of the “here and now” using fixed-duration sliding windows. The analysis uses a suite of common network diagnostics, including the distributions of degrees, distances, and clustering, to track network structure. Several random models that call these diagnostics as parameters help tease them apart as factors from the values of others. Some behaviors are consistent over the entire interval, but most diagnostics indicate that the network’s structural evolution is dominated by occasional dramatic shifts in otherwise steady trends. These behaviors are not distributed evenly across the network; stark differences in evolution can be observed between two major subnetworks, loosely thought of as “pure” and “applied”, which approximately partition the aggregate. The paper characterizes two major events along the mathematics network trajectory and discusses possible explanatory factors.