A survey of light-vehicle driver education curriculum on sharing the road with heavy vehicles

IntroductionLight-vehicle driver education programs that contain content about sharing the road with heavy vehicles may be helpful in reducing future light-vehicle/heavy-vehicle interactions. However, the extent of curricula in the United States including such content is unclear.MethodResearchers developed an online survey targeted at instructors/administrators of state driver education programs to identify curricula addressing heavy vehicles and to determine perceived effectiveness.ResultsNinety-one percent of respondents indicated that the light-vehicle driver education curriculum they teach/administer included a component covering how to safely share the road with heavy vehicles (82% perceived this component to be effective).DiscussionAlthough a large proportion of these programs included a component on how to safely share the road with heavy vehicles, participants indicated there may be room for improvement.Impact on IndustryParticipants recommended that future improvements to driver education programs include updated materials and student hands-on experience with heavy vehicles.     

Usability of the climate-resilient nature-based sand motor pilot,The Netherlands

Coastline maintenance in the Netherlands, formally in place since 1990, aims at a sustainable preservation of coastal flood protection. Over 25 years annual assessments, comparing the actual coastline positions with the 1990 reference position of the coastline, have governed the execution of sand nourishments following an adaptive management method. This method involves yearly assessment of the coastline based on measurements, design and adoption of nourishment strategies and measures and execution of the nourishments. This management approach has enabled learning and introduction of innovations in coastline maintenance. For instance, in comparison to the early nineties, nourishments are now placed more on the foreshore and the yearly nourishment budget has doubled. The most recent innovation in coastline maintenance is the ‘Sand Motor’, a nature-based nourishment approach, which concentrates the regular nourishments in space and time, given that natural processes should redistribute the sediment over the wider coastal system. In contrast to regular nourishments, the Sand Motor combines flood protection with nature and recreational objectives and is much larger in dimensions. Five years after the construction of the Sand Motor we investigate its usability in this article. We present the results of first Sand Motor evaluation and draw conclusion on the adoption and usefulness of it for coastline management from the perspective of the adaptive management method used in coastline maintenance. Recent evaluation of the monitoring data shows that the large amount of sand used for the Sand Motor has a positive impact on coastal protection. Bridging between the Sand Motor pilot and daily nourishement practice is however not yet achieved.     

Kinetics of chromate adsorption on goethite in the presence of sorbed silicic acid

The adsorption of chromate on mineral surfaces has received much attention due to its toxicity in natural systems. Spectroscopic studies have demonstrated that chromate forms inner-sphere complexes on variable-charge surfaces. However, in natural systems chromate has been observed to be fairly mobile, which has been explained by the presence of naturally occurring ligands competing with chromate for mineral surface sites. Silicic acid is a ubiquitous ligand in soil and water environments and also sorbs strongly to variable-charge surfaces. Yet little research has examined its influence on chromate adsorption to variable-charge surfaces such as goethite. This study examined the influence of silicic acid (0.10 and 1.0 mM) on the adsorption kinetics of chromate (0.05 and 0.10 mM) on goethite over a range of common soil pH values (4, 6, and 8). The rate and total quantity of chromate adsorption decreased in all the experiments except at a pH value of 4 and a chromate concentration of 0.05 mM. The inhibition of chromate adsorption ranged from 3.1% (pH = 4, Si = 0.10 mM, chromate = 0.10 mM) to 83.3% (pH = 8, Si = 1.0 mM, chromate = 0.05 mM). The rate of chromate adsorption decreased with an increase in pH and silicic acid concentration. This was attributed to a reduction in the surface potential of goethite on silicic acid adsorption as well as a competition for surface sites. The presence of naturally occurring ligands such as silicic acid may be responsible for the enhanced mobility of chromate in natural systems and demonstrates the importance of competitive adsorption for evaluating the mobility of trace elements.     

Electrostatic effects in vortical flows

Electrostatic forces have been shown to significantly enhance the collection efficiency of cyclones. In this paper, an analytic model will be developed for the effect of an applied electric field on charged particle trajectories within a laminar, two-dimensional vortical flow. Boundary conditions for particle injection are developed and collection efficiencies are predicted.     

Macroinvertebrate biomonitoring in intermittent coastal plain streams impacted by animal agriculture

Little attention has been given to the ecology of intermittent coastal plain streams in the southeastern United States, and it is not known whether available macroinvertebrate biomonitoring methods reliably detect degradation in these streams. This study compared differences in biomonitoring metrics between reference and agricultural streams, and between the flow period (January-April) and the intermittent flow period (May-December). Percentages of crustaceans, isopods, and Ephemeroptera-Plecoptera-Trichoptera (EPT) were significantly higher at the reference site than the two most impacted sites during the flow period, probably resulting from the abundance of leaf litter and lower temperatures. During this same period, the agriculturally impacted sites had a significantly higher percentage of dipterans--a group that thrives in the silty, nutrient-rich waters. Four metrics (percent Crustacea, Isopoda, Diptera, and EPT) had no overlap between values for the most impacted and the least impacted sites during the flow period, but no metrics were able to detect more discrete differences among sites. Sites were physically and biologically similar during the intermittent period when natural stresses (i.e., stagnant water, high temperatures, low dissolved oxygen) were high, with many metrics, such as percentages of dominant family, burrowers, chironomids, and dipterans becoming similar at all sites. Our findings indicate that development of a better understanding of invertebrate fauna in reference conditions and of the natural variation in intermittent streams is necessary to develop effective biomonitoring programs for these systems.     

Perchlorate retention and mobility in soils

Adsorption and release of perchlorate in a variety of soils, minerals, and other media were studied when the solid media were exposed to low and high aqueous solutions of perchlorate salts. Low level ClO4- exposure was investigated by subjecting triplicate 5.0 g portions of a solid medium (38 different soils, minerals, or dusts) to 25 mL of an aqueous ammonium perchlorate (NH4ClO4) solution containing 670 ng mL(-1) (6.8 microM) perchlorate. This corresponds to a perchlorate-to-soil ratio of 3.4 microg g(-1) (34 nmol g(-1)). At this level of exposure, more than 90% of the perchlorate was recovered in the aqueous phase, as determined by ion chromatography. In some cases, more than 99% of the perchlorate remained in the aqueous phase. In some cases, the apparent loss of aqueous perchlorate was not clearly distinguishable from the variation due to experimental error. The forced perchlorate anion exchange capacities (PAECs) were studied by soaking triplicate 5.0 g portions of the solid media in 250 mL of 0.20 M sodium perchlorate (NaClO4) followed by repeated deionized water rinses (overnight soaks with mixing) until perchlorate concentrations fell below 20 ng mL(-1) in the rinse solutions. The dried residua were leached with 15.0 mL of 0.10 M sodium hydroxide. The leachates were analyzed by ion chromatography and the perchlorate concentrations thus found were subsequently used to calculate the PAECs. The measurable PAECs of the insoluble and settleable residua ranged from 4 to 150 nmol g(-1) (micromol kg(-1)), with most in the 20-50 nmol g(-1) range. In some soils or minerals, no sorption was detectable. The mineral bentonite was problematic, however. Overall, the findings support the widely accepted idea that perchlorate does not appreciably sorb to soils and that its mobility and fate are largely influenced by hydrologic and biologic factors. They also generally support the idea that intrasoil perchlorate content is depositional rather than sorptive. On the other hand, sorption (anion replacement) of perchlorate appears to occur in some soils. Therefore, the measurement of perchlorate in soils requires accounting for ion exchange phenomena; leaching with water alone may give inaccurate results. If perchlorate anion exchange is confirmed to be negligible, then leaching procedures may be simplified accordingly.     

Lagrangian sampling of 3-D air quality model results for regional transport contributions to sulfate aerosol concentrations at Baltimore,MD, in summer 2004

We use ensemble-mean Lagrangian sampling of a 3-D Eulerian air quality model, CMAQ, together with ground-based ambient monitors data from several air monitoring networks and satellite (MODIS) observations to provide source apportionment and regional transport vs. local contributions to sulfate aerosol and PM_2.5 concentrations at Baltimore, MD, for summer 2004. The Lagrangian method provides estimates of the chemical and physical evolution of air arriving in the daytime boundary layer at Baltimore. Study results indicate a dominant role for regional transport contributions on those days when sulfate air pollution is highest in Baltimore, with a principal transport pathway from the Ohio River Valley (ORV) through southern Pennsylvania and Maryland, consistent with earlier studies. Thus, reductions in sulfur emissions from the ORV under the EPA's Clean Air Interstate Rule may be expected to improve particulate air quality in Baltimore during summer. The Lagrangian sampling of CMAQ offers an inexpensive and complimentary approach to traditional methods of source apportionment based on multivariate observational data analysis, and air quality model emissions separation. This study serves as a prototype for the method applied to Baltimore. EPA is establishing a system to allow air quality planners to readily produce and access equivalent results for locations of their choice.