Using Meteorological Model Output as a Surrogate for On-Site Observations to Predict Deposition Velocity

The National Oceanic and Atmospheric Administration's Multi-Layer Model (NOAA-MLM) is used by several operational dry deposition networks for estimating the deposition velocity of O₃, SO₂, HNO₃, and particles. The NOAA-MLM requires hourly values of meteorological variables. Since collection of on-site meteorology can be expensive, a study was performed to compare NOAA-MLM predicted deposition velocitiesusing modeled meteorological data in lieu of on-site meteorological data. NOAA-MLM was run for three sites in the Clean Air Status and Trends Network using on-site data as well as the output of two mesoscale meteorological models, Eta and MM5. The differences between the deposition velocities predictedusing the mesoscale models and those predicted using the on-sitemeteorological measurements ranged from –0.001 to 0.106 cm s^-1 and were within the model error determined in NOAA-MLM evaluation studies. This research shows that the NOAA-MLM is particularly sensitive to differences in atmospheric turbulence,soil moisture budget, and canopy wetness.(On assignment to the National Exposure Research Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina.) (author for correspondence, e-mail     

Identifying an appropriate driving behaviour scale for the occupational driving context: The DBQ vs. the ODBQ

Self reported driving behaviour in the occupational driving context has typically been measured through scales adapted from the general driving population (i.e., the Manchester Driver Behaviour Questionnaire, (DBQ), Reason et al., 1990). However, research suggests that occupational driving is influenced by unique factors operating within the workplace environment, and thus, a behavioural scale should reflect those behaviours prevalent and unique within the driving context. To overcome this limitation, Newnam et al. (2011) developed the Occupational Driver Behaviour Questionnaire ((ODBQ), Newnam et al., 2011) which utilises a relevant theoretical model to assess the impact of the broader workplace context on driving behaviour. Although the theoretical argument has been established, research is yet to examine whether the ODBQ or the DBQ is a more sensitive measure of the workplace context. As such, this paper identifies selected organisational factors (i.e., safety climate and role overload) as predictors of the DBQ and the ODBQ and compares the relative predictive value in both models. In undertaking this task, 248 occupational drivers were recruited from a community-oriented nursing population. As predicted, hierarchical regression analyses revealed that the organisational factors accounted for a significantly greater proportion of variance in the ODBQ than the DBQ. These findings offer a number of practical and theoretical applications for occupational driving practice and future research.     

Isochromosome 5p mosaicism at prenatal diagnosis: observations and outcomes in six cases at chorionic villus sampling and one at amniocentesis

We present six cases of 47,+i(5p)/46 mosaicism diagnosed at chorionic villus sampling (CVS), this being the first prospective series to be reported. The clinical indication in each was advanced maternal age. Further prenatal studies in four (amniocentesis, plus fetal blood sampling in one) did not show the isochromosome. In one case, subsequent amniocentesis showed 1/48 in situ colonies with the isochromosome, but fetal blood was karyotypically normal. These five pregnancies resulted in phenotypically normal livebirths; further normal follow-up reports (from age 4 months through 4 years) are noted in four of these. Analysis of placental tissue in one case confirmed the presence of the i(5p) mosaicism. In the remaining case, in which 100% of CVS cultured cells had the i(5p), the pregnancy was terminated. Fetal skin fibroblasts did not show the i(5p). Thus, in none of these six cases was true fetal mosaicism detected, nor an abnormal phenotype noted. We suggest that a 47,+i(5p)/46 karyotype, detected at CVS, may frequently reflect confined placental mosaicism. In addition, we report a case of the primary diagnosis of 47,+i(5p)/46 mosaicism at amniocentesis. The infant appeared normal at birth, but a brain malformation was subsequently identified. Copyright © 2002 John Wiley & Sons, Ltd.     

Landscape Character and Fish Assemblage Structure and Function in Western Lake Superior Streams: General Relationships and Identification of Thresholds

As part of a comparative watershed project investigating land-cover/land-use disturbance gradients for streams in the western Lake Superior Basin, we examined general relationships between landscape character and fish assemblage structure and function. We also examined the shape of those relationships to identify discontinuity thresholds where small changes in landscape character were associated with marked shifts in the fish assemblages. After completing a geographic analysis of second- and third-order watersheds in the western Lake Superior drainage, we randomly selected 48 streams along mature forest and watershed storage gradients in 2 hydrogeomorphic regions as our study sites. During the summers of 1997 and 1998, we used electrofishing to sample fish assemblages from each stream. Each of the landscape factors was significantly associated with fish assemblage structure and function based on analysis of covariance. Watershed storage was related to the greatest number of fish assemblage characteristics, but hydrogeopmorphic region and mature forest cover were strongly associated as well. The hydrogeomorphic region also mediated relationships between watershed character and fish assemblages. Discontinuity thresholds for our fish assemblages averaged 11% for watershed storage and 50% for watershed mature forest cover based on piecewise regression analysis. Although many of the landscape–fish relationships might have been manifest through effects on in-stream habitat, our results highlight the importance of management and land-use planning decisions at the watershed and landscape scales.Published online     

Effects of environmental factors on 1,3-dichloropropene hydrolysis in water and soil

Hydrolysis is the major pathway for fumigant 1,3-dichloropropene (1,3-D) degradation in water and soil, yet the process is not well understood. Experiments were conducted to investigate the effect of various environmental factors on the rate of 1,3-D hydrolysis. Cis-, trans-1,3-D and their isomeric mixture were spiked into water and Arlington soil (coarse-loamy, mixed, thermic Haplic Durixeralfs) and incubated under different conditions. The rate of 1,3-D hydrolysis in water and soil were evaluated based on its residual amount and Cl- release, respectively. 1,3-D hydrolyzed rapidly in deionized water, with a half-life of 9.8 d at 20 degrees C. The hydrolysis was pH dependent, with low pH inhibiting and high pH favoring the reaction. Other factors such as isomeric differences, photo irradiation, suspended particles, and small amounts of co-solutes had little effect on the reaction. In soil, 1,3-D hydrolyzed following pseudo first-order kinetics. The hydrolysis rate constant increased with soil moisture content and decreased with the initial 1,3-D concentration. At 20 degrees C, > 60% of the 1,3-D applied at < 0.61 g kg(-1) in 10% moisturized soil hydrolyzed within 30 d. The soil particle size and mineralogy had little effect on the reaction rate. Organic matter promoted 1,3-D degradation via direct substitution reactions, and the trans-isomer showed preference over the cis- to react with certain organic molecules. Microbial contributions were initially insignificant, and became important as soil microorganisms adapted to the fumigant. The results suggest that to accelerate 1,3-D degradation, pH, soil moisture, and organic amendment should be considered.     

Nitrate distributions and source identification in the Abbotsford-Sumas Aquifer,northwestern Washington State

The Abbotsford-Sumas Aquifer is a shallow, predominantly unconfined aquifer that spans regions in southwestern British Columbia, Canada and northwestern Washington, USA. The aquifer is prone to nitrate contamination because of extensive regional agricultural practices. A 22-month ground water nitrate assessment was performed in a 10-km2 study area adjacent to the international boundary in northwestern Washington to examine nitrate concentrations and nitrogen isotope ratios to characterize local source contributions from up-gradient sources in Canada. Nitrate concentrations in excess of 10 mg nitrate as nitrogen per liter (mg N L(-1)) were observed in ground water from most of the 26 domestic wells sampled in the study area, and in a creek that dissects the study area. The nitrate distribution was characteristic of nonpoint agricultural sources and consistent with the historical documentation of agriculturally related nitrate contamination in many parts of the aquifer. Hydrogeologic information, nitrogen isotope values, and statistical analyses indicated a nitrate concentration stratification in the study area. The highest concentrations (> 20 mg N L(-1)) occurred in shallow regions of the aquifer and were linked to local agricultural practices in northwestern Washington. Nitrate concentrations in excess of 10 mg N L(-1) deeper in the aquifer (> 10 m) were related to agricultural sources in Canada. The identification of two possible sources of ground water nitrate in northwestern Washington adds to the difficulty in assessing and implementing local nutrient management plans for protecting drinking water in the region.     

Iron-based flow batteries to store renewable energies

The development of cost-effective and eco-friendly alternatives of energy storage systems is needed to solve the actual energy crisis. Although technologies such as flywheels, supercapacitors, pumped hydropower and compressed air are efficient, they have shortcomings because they require long planning horizons to be cost-effective. Renewable energy storage systems such as redox flow batteries are actually of high interest for grid-level energy storage, in particular iron-based flow batteries. Here we review all-iron redox flow battery alternatives for storing renewable energies. The role of components such as electrolyte, electrode and membranes in the overall functioning of all-iron redox flow batteries is discussed. The effect of iron–ligand chemistry on the performance of battery is highlighted. Additionally, a brief contextual background and fundamentals of redox flow batteries are provided. The design aspects, progress in research, mathematical modeling, cost estimations and future prospects of using all-iron energy systems are discussed in the context of future grid-level energy storage.     

Cerium dioxide and composites for the removal of toxic metal ions

The presence of contaminants in potable water is a cause of worldwide concern. In particular, the presence of metals such as arsenic, lead, cadmium, mercury, chromium can affect human health. There is thus a need for advanced techniques of water decontamination. Adsorbents based on cerium dioxide (CeO₂), also named ‘ceria,’ have been used to remove contaminants such as arsenic, fluoride, lead and cadmium. Ceria and composites display high surface area, controlled porosity and morphology, and abundance of functional groups. They have already found usage in many applications including optical, semiconductor and catalysis. Exploiting their attractive features for water treatment would unravel their potential. We review the potential of ceria and its composites for the removal of toxic metal ions from aqueous medium. The article discusses toxic contaminants in water and their impact on human health; the synthesis and adsorptive behavior of ceria-based materials including the role of morphology and surface area on the adsorption capacity, best fit adsorption isotherms, kinetic models, possible mechanisms, regeneration of adsorbents; and future perspectives of using metal oxides such as ceria. The focus of the report is the generation of cost-effective oxides of rare-earth metal, cerium, in their standalone and composite forms for contaminant removal.