2,4,6-Trinitrotoluene in soil and groundwater under a waste lagoon at the former Explosives Factory Maribyrnong (EFM), Victoria, Australia

Energetic materials contamination was investigated at the former Explosives Factory Maribyrnong, Victoria, Australia. Spectrophotometric/high performance liquid chromatography (HPLC) analysis was utilised to delineate a 5 tonne crystalline 2,4,6-trinitrotoluene (TNT) source in a former process waste lagoon that was found to be supplying contaminant leachate to the surficial clay aquitard with a maximum-recorded concentration of 7.0 ppm TNT. Groundwater within underlying sand and gravel aquifers was found to be uncontaminated due to upward hydraulic gradients resulting in slow plume development and propagation. Adsorption and microcosm test results from a parallel study were used as input parameters to simulate aqueous TNT transport in the clay aquitard using ATRANS20 software. The simulated TNT plume was localised within a few metres of the source, and at steady state, though leaching rate calculations suggest that without mitigation or other changes to the system, persistence of the source would be approximately 2,000 years. Remediation strategies may involve removal of the near surface source zone and infilling with an impermeable capping to impede leaching while facilitating ongoing natural attenuation by anaerobic degradation.     

Mixed messages in iron oxide–copper–gold systems of the Cloncurry district,Australia: insights from PIXE analysis of halogens and copper in fluid inclusions

Proterozoic rocks of the Cloncurry district in NW Queensland, Australia, are host to giant (tens to hundreds of square kilometers) hydrothermal systems that include (1) barren regional sodic–calcic alteration, (2) granite-hosted hydrothermal complexes with magmatic–hydrothermal transition features, and (3) iron oxide–copper–gold (IOCG) deposits. Fluid inclusion microthermometry and proton-induced X-ray emission (PIXE) show that IOCG deposits and the granite-hosted hydrothermal complexes contain abundant high temperature, ultrasaline, complex multisolid (type 1) inclusions that are less common in the regional sodic–calcic alteration. The latter is characterized by lower salinity three-phase halite-bearing (type 2) and two-phase (type 3) aqueous inclusions. Copper contents of the type 1 inclusions (>300 ppm) is higher than in type 2 and 3 inclusions (<300 ppm), and the highest copper concentrations (>1,000 ppm) are found both in the granite-hosted systems and in inclusions with Br/Cl ratios that are consistent with a magmatic source. The Br/Cl ratios of the inclusions with lower Cu contents are consistent with an evaporite-related origin. Wide ranges in salinity and homogenization temperatures for fluid inclusions in IOCG deposits and evidence for multiple fluid sources, as suggested by halogen ratios, indicate fluid mixing as an important process in IOCG genesis. The data support both leaching of Cu by voluminous nonmagmatic fluids from crustal rocks, as well as the direct exsolution of Cu-rich fluids from magmas. However, larger IOCG deposits may form from magmatic-derived fluids based on their higher Cu content.     

Functional,Phylogenetic and Host-Geographic Signatures of <Emphasis Type="Italic">Labyrinthula</Emphasis> spp. Provide for Putative Species Delimitation and a Global-Scale View of Seagrass Wasting Disease

Seagrass meadows form ecologically and economically valuable coastal habitat on every continental margin except the Antarctic, but their areal extent is declining by approximately 2–5 % per year. Seagrass wasting disease is a contributing factor in these declines, with the protist Labyrinthula identified as the etiologic agent. To help elucidate the role of Labyrinthula spp. in global seagrass declines, we surveyed roughly one fourth of all seagrass species to identify Labyrinthula diversity at the strain and/or species level, combining results from culturing methods and two common nuclear DNA markers: the ITS and 18S regions of the ribosomal RNA gene complex. After assaying a subset of the resulting isolates (of which 170 were newly sequenced), we produced a cladogenic context for putative seagrass-pathogenic versus non-pathogenic Labyrinthula while also defining host and geographic ranges. Assays also suggest that pathogenicity is consistently high (when present; and, even when comparing susceptibility of US East- versus West Coast Zostera marina hosts) while virulence is variable, that some isolate-host combinations have the potential for host cross-infection, and that several modes of transmission can be effective. Taken together, these data provide additional means for delimiting putative species of Labyrinthula, suggesting at least five seagrass-pathogenic and perhaps ten or more non-pathogenic marine “species”, yielding a working definition for ecologists and epidemiologists attempting to reconcile the sundry data related to seagrass wasting disease.     

Hybrid three-scale model for evolving pore-scale geometries

We consider flow and upscaling of flow properties from pore scale to Darcy scale, when the pore-scale geometry is changing. The idea is to avoid having to solve for the pore evolution at the pore scale, because this results in unmanageable complexity. We propose to use stochastic modeling to parametrize plausible modifications of the pore geometry and to construct distributions of permeability parametrized by Darcy-scale variables. To localize the effects of, e.g., clogging, we introduce an intermediate scale of pore-network models. We use local Stokes solvers to calibrate the throat permeability.     

Deglaciation ages and meltwater routing in the Fort McMurray region,northeastern Alberta and northwestern Saskatchewan,Canada

A field-based reconstruction of the deglacial paleogeography in the Fort McMurray area permits: 1) constraining the timing of meltwater routing to the Arctic from the present Hudson Bay drainage basin; and 2) minimum-age estimates for ice-margin positions that can be used to constrain ice-sheet modeling results. A downslope recession of the Laurentide Ice Sheet resulted in a series of proglacial lakes forming between the ice margin and higher land to the southwest. The paleogeography of these lakes is poorly constrained in part from the masking effect of boreal forest vegetation and map-scale issues. However, recent space-shuttle based DEMs increase the number and spatial extent of moraines identified within the study area resulting in a coherent pattern of ice margin retreat focused on the Athabasca River valley. An intensive lake-coring program resulted in a minimum ten-fold increase in the radiocarbon database used to limit moraine ages. Results indicate that deglaciation in this region was younger than previously reported, and it is likely that the meltwater could not drain northward to the Arctic Ocean from any source southeast of the Fort McMurray area until approximately 9850–9660 ¹⁴C BP.     

Transboundary air pollution and environmental justice: Vancouver and Seattle compared

This paper comparatively analyzes the association between urban neighborhood socioeconomic markers and ambient air pollution in Vancouver and Seattle, the two largest urban regions in the Georgia Basin-Puget Sound (GB-PS) international airshed. Given their similarities and common airshed, Vancouver and Seattle are useful comparators addressing not only whether socioeconomic gradients exist in urban environmental quality but also identifying clues to differences in these gradients between Canadian and American cities. Large air quality sampling campaigns and pollution regression mapping provide the pollution data, in this case nitrogen dioxide—a marker of traffic emissions considered the most important air pollutant for human health in the typical North American city. Pollution data are combined with neighborhood census data for regression and spatial analyses. Median household income is the most consistent correlate of air pollution in both cities, including their most polluted neighborhoods, although neighborhoods marked by immigrant populations do not correlate with high pollution levels in Vancouver as they do in Seattle.