A technique for cutting brittle undisturbed lateritic soil block samples

This note describes a technique for cutting undisturbed brittleblock samples into smaller specimens for further geotechnical testing. This technique revealed very useful in dealing with collapsible soils, where the sampling is recommended to be donewith block soil samples. A further use of this technique as an efficient way for sampling collapsible soils is proposed.     

N-nitrosodimethylamine in drinking water using a rapid,solid-phase extraction method

A simple, rapid method for the extraction of N-nitrosodimethylamine (NDMA) from drinking and surface waters was developed using Ambersorb 572. Development of an alternative method to classical liquid-liquid extraction techniques was necessary to handle the workload presented by implementation of a provincial guideline of 9 ppt for drinking water and a regulatory level of 200 ppt for effluents. A granular adsorbent, Ambersorb 572, was used to extract the NDMA from the water in the sample bottle. The NDMA was extracted from the Ambersorb 572 with dichloromethane in the autosampler vial. Method characteristics include a precision of 4 % for replicate analyses, an accuracy of 6 % at 10 ppt and a detection limit of 1.0 ppt NDMA in water. Comparative data between the Ambersorb 572 method and liquid-liquid extraction showed excellent agreement (average difference of 12 %). With the Ambersorb 572 method, dichloromethane use has been reduced by a factor of 1,000 and productivity has been increased by a factor of 3–4. Monitoring of a drinking water supply showed rapidly changing concentrations of NDMA from day to day.     

Sequential sampling: A cost-effective approach for monitoring benthic macroinvertebrates in environmental impact assessments

Sequential sampling is a method for monitoring benthic macroinvertebrates that can significantly reduce the number of samples required to reach a decision, and consequently, decrease the cost of benthic sampling in environmental impact assessments.Rather than depending on a fixed number of samples, this analysis cumulatively compares measured parameter values (for example, density, community diversity) from individual samples, with thresholds that are based on specified degrees of precision.In addition to reducing sample size, a monitoring program based on sequential sampling can provide clear-cut decisions as to whethera priori-defined changes in the measured parameter(s) have or have not occurred. As examples, sequential sampling programs have been developed to evaluate the impact of geothermal energy development on benthic macroinvertebrate diversity at The Geysers, California, and for monitoring the impact of crude oil contamination on chironomid midge [Cricotopus bicinctus (Meigen) andC. mackenziensis Oliver] population densities in the Trail River, Northwest Territories, Canada.     

Characterization of drug and alcohol use among senior drivers fatally injured in U.S. motor vehicle collisions, 2008–2012

Objective: Adults 65 years of age and older comprise the fastest growing demographic in the United States. As substance use is projected to increase in this population, there is concern that more seniors will drive under the influence of impairing drugs. The purpose of this analysis was to characterize the drug and alcohol usage among senior drivers fatally injured (FI) in traffic collisions.

Methods: Data from the Fatality Analysis Reporting System were analyzed from 2008 to 2012. Commonly used classes and specific drugs were explored. Rates of drug use, multiple drugs, concomitant drug and alcohol use, and alcohol use alone were generated using Poisson regression with robust error variance estimation. Rates were compared to a reference population of FI middle-aged drivers (30 to 50 years old) using rate ratios.

Results: Drug use among FI senior drivers occurred in 20.0% of those tested. Among drug-positive FI senior drivers, narcotics and depressants were frequent. The prevalence of testing positive for any drug, multiple drugs, combined drug and alcohol, and alcohol use alone among FI seniors were 47% less (relative risk [RR] = 0.53, 95% confidence interval [CI], 0.47, 0.62), 59% less (RR = 0.41, 95% CI, 0.34, 0.51), 87% less (RR = 0.13, 95% CI, 0.09, 0.19), and 77% less (RR = 0.23, 95% CI, 0.19, 0.28), respectively, compared to FI middle-aged drivers.

Conclusions: Though overall drug use is less common among FI senior drivers relative to FI middle-aged drivers, driving under the influence of drugs may be a relevant traffic safety concern in a portion of this population.     

New fossil ants in French Cretaceous amber (Hymenoptera: Formicidae)

Recent studies on the ant phylogeny are mainly based on the molecular analyses of extant subfamilies and do not include the extinct, only Cretaceous subfamily Sphecomyrminae. However, the latter is of major importance for ant relationships, as it is considered the most basal subfamily. Therefore, each new discovery of a Mesozoic ant is of high interest for improving our understanding of their early history and basal relationships. In this paper, a new sphecomyrmine ant, allied to the Burmese amber genus Haidomyrmex, is described from mid-Cretaceous amber of France as Haidomyrmodes mammuthus gen. and sp. n. The diagnosis of the tribe Haidomyrmecini is emended based on the new type material, which includes a gyne (alate female) and two incomplete workers. The genus Sphecomyrmodes, hitherto known by a single species from Burmese amber, is also reported and a new species described as S. occidentalis sp. n. after two workers remarkably preserved in a single piece of Early Cenomanian French amber. The new fossils provide additional information on early ant diversity and relationships and demonstrate that the monophyly of the Sphecomyrminae, as currently defined, is still weakly supported.     

Plant acclimation to elevated CO2—From simple regularities to biogeographic chaos

Upon exposure to altered levels of CO₂, plants express a variety of acclimations to CO₂ directly, over and above acclimations to indirect changes in temperature and water regimes. These acclimations commonly include increased photosynthetic CO₂ assimilation and increased water-use efficiency with reduced N content and reduced stomatal conductance. The robust generic acclimations are explicable by combining simple models of carboxylation, stomatal control, energy balance, and functional balance. Species- or genotype-specific acclimations are overlaid on these generic acclimations. Several such specific acclimations that are often seen are readily incorporated in an extended model. These specific acclimations generate a great spread of values in key performance measures of photosynthesis, water- and N-use efficiencies, and rates of water and N use, even among C₃ species that are the focus of this work. These performance measures contribute strongly to relative fitness and thus to evolving biogeographic distributions. The spread in fitness values is so large as to impend “chaotic” shifts in biogeography (and, ultimately, evolution) that are not understandable with models specific to species or functional groups; rather, a systematic study of key physiological and developmental parameters is merited. Also merited is a coherent extension of the model used here, or similar models, to include other phenomena, including mycorrhizal associations, transience in resource availability, etc. The composition of useful approximate fitness functions from physiological and allocational responses is a major challenge, with some leads originating from the model. In the search to extract patterns of responses, arguments based on the responses being close to optimal or adaptive will be misleading, in view of the absence of selection pressure to perform adaptively at high CO₂ for over 20 million years. I offer suggestions for more useful research designs.     

Global Warming and the Species Richness of Bats in Texas

General circulation models provide predictions for global climate under scenarios of increased atmospheric CO₂. Climate change is expected to lead directly to changes in distributions of vegetation associations. Distribution of animals will also change to the extent that animals rely on vegetation for food or shelter. Bat species in Texas appear to be restricted, in part, by the availability of roosts. We used geographic information systems and the Holdridge vegetation-climate association scheme to model the effect of climate change on bat distributions and species richness in Texas. Habitat characteristics for each species were identified from the literature and included vegetation, topography, and availability of caves. We assumed caves and topography to be fixed relative to climate. Vegetation changes were predicted from the Holdridge vegetation-climate association scheme. The redistribution of bats following climate change was predicted based on the new locations of suitable habitat characteristics. Under conditions of global warming tropical forests were predicted to expand into Texas; tree-roosting bats were sensitive to this change in vegetation. Cavity-roosting bats were less affected by changes in vegetation, but, where response was predicted, ranges decline.     

Potentially toxic metals in ombrotrophic peat along a 400 km English-Scottish transect

Four samples of ombrotrophic peat were collected from each of 10 upland locations in a transect from the southern Pennines to the Highland Boundary Fault, a total distance of ca. 400 km. Bulk compositions and other properties were determined. Total contents of Al and heavy metals (Ni, Cu, Zn, Cd, Pb) were determined following digestion with hydrofluoric acid, and concentrations of metals extractable with dilute nitric acid were also measured. Supernatants obtained from aqueous extractions of the peat samples were analysed for pH, major cations and anions, dissolved organic carbon and dissolved metals, and concentrations of free metal ions (Al(3+), Ni(2+), etc.) were estimated by applying a chemical speciation model. Both total and HNO(3)-extractable metal concentrations varied along the transect, the highest values being found at locations close to industrial and former mining areas. The HNO(3)-extractable soil metal contents of Ni, Cu and Cd were appreciably lower than lowest-observed-effect-concentrations (LOEC) for toxicity towards microorganisms in acid, organic rich soils. However, the contents of Zn at two locations, and of Pb at five locations exceeded LOECs, suggesting that they may be exerting toxic effects in the peats. Soil solution concentrations of free heavy metal ions (Cu(2+), Zn(2+), Cd(2+), Pb(2+)) were substantially lower than LOECs for toxicity towards vascular plants, whereas concentrations of Al(3+) were near to toxic levels at two locations.     

New experimental methods for the development and evaluation of aerosol samplers

An understanding of the scaling laws governing aerosol sampler performance leads to new options for testing aerosol samplers at small scale in a small laboratory wind tunnel. Two methods are described in this paper. The first involves an extension of what is referred to as the "conventional" approach, in which scaled aerosol sampler systems are tested in a small wind tunnel while exposed to relatively monodisperse aerosols. Such aerosols are collected by test and reference samplers respectively and assessed gravimetrically. The new studies were carried out for a modified, low flowrate version of the IOM personal inhalable aerosol sampler. It was shown that such experiments can be carried out with a very high level of repeatability, and this supported the general validity of the aerosol sampler scaling laws. The second method involves a novel testing system and protocol for evaluating the performances of aerosol samplers. Here, scaled aerosol samplers of interest are exposed to polydisperse aerosols, again in a small wind tunnel. In this instance, the sampled particles are counted and sized using a direct-reading aerodynamic particle sizer (the APS). A prototype automated aerosol sampler testing system based on this approach was built and evaluated in preliminary experiments to determine the performance of another modified version of the IOM personal inhalable aerosol sampler. The design of the new test system accounts for the complex fluid mechanical coupling that occurs near the sampler inlet involving the transition between the external flow outside the sampler and the internal airflow inside the sampler, leading in turn to uncontrolled particle losses. The problem was overcome by the insertion of porous plastic foam plugs. where the penetration characteristics are well understood, into the entries of both the test and the reference samplers. Preliminary experiments with this new system also supported the general validity of the aerosol sampler scaling laws. In addition, they demonstrated high potential that this approach may be applied in a standardised aerosol testing method and protocol.