Interlaboratory evaluation of an extraction and fluorescence method for the determination of trace beryllium in soils

Analytical methods for the determination of trace beryllium in soils are needed so that anthropogenic sources of this element can be distinguished from native (background) levels of beryllium. In this work, a collaborative interlaboratory evaluation of a new extraction and fluorescence-based procedure for determining beryllium in soil samples was carried out to fulfil method validation requirements for ASTM International voluntary consensus standard test methods. A Canadian reference material, CCRMP Till-1 soil, with a background beryllium concentration of 2.4 microg g(-1), was selected for study. This certified reference material (CRM) was spiked and homogenized with varying levels of beryllium oxide in order to give batches of material with beryllium concentrations of 4.36 +/- 0.69, 11.5 +/- 0.7, 124 +/- 7 and 246 +/- 16 microg g(-1) (+/- values are standard deviations). In the interlaboratory study (ILS), which was carried out in accordance with an applicable ASTM International standard practice (ASTM E691), samples of these spiked soils were subjected to extraction in dilute ammonium bifluoride at approximately 90 degrees C for 40 h. Fluorescence measurement of the extracted beryllium was carried out via detection using the high quantum yield fluorophore, hydroxybenzoquinoline sulfonate (HBQS). Interlaboratory precision estimates from six participating laboratories ranged from 0.048 to 0.103 (relative standard deviations) for the five different beryllium concentrations. Pooled bias estimates resulting from this ILS were between -0.049 and 0.177 for the various beryllium levels. These figures of merit support promulgation of the analytical procedure as an ASTM International standard test method.     

Geospatial Method to Map Potential Risk of Stormwater Thermal Pollution

Thermal pollution is a growing concern as communities strive to protect and improve the nation's waters. The purpose of this study was to develop and analyze a geospatial model that predicts the relative risk of contribution of thermal energy to surface runoff throughout an urban watershed. A geospatial‐based solution could serve as a screening method or planning element, prior to or instead of the development of a more complex simulation of mass‐load transport of thermal energy. The study's theoretical methodology integrated the thermal potential of land cover and thermal decay due to overland travel to inlets. The resulting thermal pollution potential (TPP) index value was then assigned to individual model grid cells for comparison. Analysis of results from application to a case study watershed in Blacksburg, Virginia, indicated the computational methodology is not very sensitive to changes in spatial resolution. The thermal decay constant used in the analysis was varied, and results indicated a low sensitivity to selection of this parameter. A comparison between methods of watershed delineation also indicated use of infrastructure‐corrected watershed delineation yields better results than derivation from automated techniques. The geospatial method presented may be used to reproduce a TPP risk map to prioritize thermal pollution mitigation efforts.     

Characterization and enzymatic degradation of a cross-linked bacterial polyester

The bacterial polyester, poly(-hydroxybutyrate-co--hydroxyvalerate) (PHB/V), was cross-linked with 1, 5, 7, 10, 20, and 30 wt% benzoyl peroxide by thermal decomposition reactions. Solvent extractions were carried out to determine the cross-linked fractions of the films. The sol/gel data were used to estimate cross-link densities. Films of PHB/V cross-linked with 10% benzoyl peroxide were placed in contact with purified depolymerase A secreted byP. lemoignei. These samples exhibited weight loss rates which were half that of un-cross-linked PHB/V, but the network was degraded completely by the enzyme. The results of this study suggest that anendo-type enzymatic degradation may occur, in addition to theexo-type activity, which is normally presumed to occur with theP. lemoignei depolymerase system.     

Mixed-species shoaling in fish: the sensory mechanisms and costs of shoal choice

The mechanisms and functions of mixed-species shoaling were investigated in two sympatric species of cyprinids, the chub and the European minnow, from the river Wharfe where they comprised approximately 70% of all year 0+ fish over a 20-year survey. Chub preferred conspecific shoals over heterospecific ones with olfactory cues being more important than visual ones for shoal choice. This preference was consistent with measurements of length:flank area ratios and length:weight ratios which suggest that both species are similar in appearance. When presented with mixed-species shoals, chub increased the percentage time spent with stimulus shoals with increasing proportions of conspecifics. Feeding experiments suggest that the preference for conspecific shoals is driven by interspecific competition (with minnows out-competing similar-sized chub) and the oddity effect. The importance of this work in the context of species assortment in free-ranging shoals is discussed.     

Lumbar Bone Mineral Density Phantomless Computed Tomography Measurements and Correlation with Age and Fracture Incidence

Objective: Low bone quality is a contributing factor to motor vehicle crash (MVC) injury. Quantification of occupant bone mineral density (BMD) is important from an injury causation standpoint. The first aim of this study was to validate a technique for measuring lumbar volumetric BMD (vBMD) from phantomless computed tomography (CT) scans. The second aim was to apply the validated phantomless technique to quantify lumbar vBMD in Crash Injury Research and Engineering Network (CIREN) occupants for correlation with age, fracture incidence, and osteopenia/osteoporosis diagnoses.

Methods: Quantitative CT (qCT) and dual-energy X-ray absorptiometry (DXA) were collected prospectively for 50 subjects and used to validate a technique to measure vBMD from 281 phantomless CT scans of CIREN occupants. Hounsfield unit (HU) measurements were collected from the L1–L5 vertebrae, right psoas major muscle, and anterior subcutaneous fat for all subjects and from 3 phantom ports with known mg/cc calcium hydroxyapatite values for the validation group. qCT calibration was accomplished using regressions between the phantom HU and mg/cc values to convert L1–L5 HU values to mg/cc. A phantomless calibration technique was developed where the fat and muscle HU values were linearly regressed against fat (?69 mg/cc) and muscle (77 mg/cc) to establish a conversion for L1–L5 HU measurements to mg/cc. vBMD calculated from qCT versus the phantomless method was compared for the 50 subjects to assess agreement and a mg/cc osteopenia threshold was established using DXA T-scores. CIREN HU measurements were converted to mg/cc using the phantomless technique and the mg/cc osteopenia threshold was used to compare vBMD to age, fracture incidence, and osteopenia comorbidity classifications in CIREN.

Results: Linear regression of lumbar vBMD derived from the qCT versus phantomless calibrations showed excellent agreement (R² = 0.87, P <.0001). A 145 mg/cc threshold for osteopenia was established (sensitivity = 1, specificity = 0.57) and 44 CIREN occupants had vBMD below this threshold. Of these 44 occupants, 64% were not classified as osteopenic in CIREN, but vBMD suggested undiagnosed osteopenia. Age was negatively correlated with vBMD in both sexes (P <.0001) and CIREN occupants with less than 145 mg/cc vBMD sustained an average 1.7 additional rib/sternum fractures (P =.036).

Conclusions: Because lumbar vBMD was estimated from phantomless CT scans with accuracy similar to qCT, the phantomless technique can be broadly applied to both prospectively and retrospectively assess patient bone quality for research and clinical studies related to MVCs, falls, and aging.     

Collaborative Implementation for Ecological Restoration on US Public Lands: Implications for Legal Context,Accountability, and Adaptive Management

The Collaborative Forest Landscape Restoration Program (CFLRP), established in 2009, encourages collaborative landscape scale ecosystem restoration efforts on United States Forest Service (USFS) lands. Although the USFS employees have experience engaging in collaborative planning, CFLRP requires collaboration in implementation, a domain where little prior experience can be drawn on for guidance. The purpose of this research is to identify the ways in which CFLRP’s collaborative participants and agency personnel conceptualize how stakeholders can contribute to implementation on landscape scale restoration projects, and to build theory on dynamics of collaborative implementation in environmental management. This research uses a grounded theory methodology to explore collaborative implementation from the perspectives and experiences of participants in landscapes selected as part of the CFLRP in 2010. Interviewees characterized collaborative implementation as encompassing three different types of activities: prioritization, enhancing treatments, and multiparty monitoring. The paper describes examples of activities in each of these categories and then identifies ways in which collaborative implementation in the context of CFLRP (1) is both hindered and enabled by overlapping legal mandates about agency collaboration, (2) creates opportunities for expanded accountability through informal and relational means, and, (3) creates feedback loops at multiple temporal and spatial scales through which monitoring information, prioritization, and implementation actions shape restoration work both within and across projects throughout the landscape creating more robust opportunities for adaptive management.     

Can timber and water resources be sustainably co-developed in south-eastern New South Wales, Australia?

In the south-east of New South Wales, Australia, forested catchments are largely relied upon to provide high-quality surface water at low cost to small regional communities. The forests in question are used for multiple purposes including timber production, which can result in conflicts and debate regarding the sustainability of timber and water resources being co-developed. A case study is examined where a logging operation will occur on 3.5% of the Myrtle Creek catchment that is used to supply water to the small township of Wyndham. Modelling based on the water yield response of eucalypt forests to disturbance predicts that during the first four years post-harvest, total streamflows will be increased under the ‘2010 logging’ scenario, with a maximum increase of 2.6% within the first two years. Streamflows will then likely decrease compared to the ‘no logging’ scenario and will continue to do so until regrowth reaches 28 years of age with a maximum 1.4% decrease predicted. Streamflows under both scenarios will continue to increase over time as water yield has been suppressed by forest regeneration following extensive wildfires and logging that occurred from the 1960s to 1980s. It is concluded that timber harvesting, if limited spatially and temporally, can occur without compromising catchment values and may contribute to improved forest heterogeneity and resilience. However, in the face of a changing climate and an increased likelihood of catastrophic high intensity wildfires, the future sustainability of undercapitalised small town water supplies reliant on a single water source is questionable.