The Transport of Suspended Particulates as a Function of Wind Direction and Atmospheric Conditions

Linear regression of high volume air sampler data and various meteorological parameters was used to determine a suspended particulate air pollution climatology for Albany, NY. A new method for exhibiting associations between wind direction and pollutant levels using correlation coefficients is presented. Correlations between wind direction distribution frequency and other meteorological parameters is employed to help explain differences in correlations for direction with suspended particulate levels. Results show that high particulate concentrations correlate well with southerly wind flow throughout the study area, regardless of relative location of receptor to local sources. This suggests that ambient background concentrations inherent in different air masses more consistently affected suspended particulate levels than did the diffusion from local sources during the study period. Maximum particulate advection occurs under conditions of good mixing of the boundary layer and moderate wind speeds and is enhanced further in the absence of removal processes such as rainout and washout. Trajectory analysis of selected days indicates a definite relationship between path and origin of the wind flow and regional average particulate concentration.     

The importance of group‐focused transformational leadership and felt obligation for helping and group performance

Leaders face a challenge to simultaneously motivate workgroups and the individuals within them. Recent criticisms highlight the need to deconstruct broad leadership constructs to offer better theoretical insight into the effects of specific leadership behaviors on groups versus individuals. We address this call by exploring the effects of group‐focused and individual‐focused aspects of transformational leadership. Applying social identity theory, we theorize that group‐focused transformational leadership is key to fostering felt obligation, motivating helping behavior, and enhancing group performance, whereas individual‐focused leadership may only foster helping when individuals also feel a sense of obligation toward their workgroup. In a field study of 260 employees reporting to 36 supervisors in a skilled trade company, we find support for these predictions using multilevel structural equation modeling and multilevel mixed effects modeling. Thus, group‐focused (vs. individual‐focused) transformational leadership and subsequent felt obligation are important antecedents for encouraging helping and, in turn, workgroup performance.     

Analyzing maps of dispersal around a single focus

The spatial pattern of organisms may be used to characterize their dispersal, quantify spread or estimate the point of introduction of an alien species. Their distribution may be represented by maps of individuals, or by counts or by presence/absence at known positions within a sampled area. The problems and relative merits of these different forms of data for spatial inference are discussed. Three datasets concerning dispersal from a single focus are analyzed: counts of aphids, Rhopalosiphum padi and Sitobion avenae, on barley plants, Hordeum vulgare, grown in experi- mental trays; mapped locations of couch grass, Elymus repens, tillers within plots of a field experiment; locations of sightings of the lupin aphid, Macrosiphum albifrons, as it invaded Great Britain between 1981 and 1984. A method for generating maps from counts is proposed to overcome problems caused by recording imprecision. Several statistics are used to quantify dispersal and spatial pattern in the experimental data and together provide a clear picture of the spatial pattern observed; they enabled several effects of the experimental treatments to be identified. The value of the statistics are compared. Estimates of the source of the lupin aphid invasion are obtained using the backtracking methods of Perry (1995b) and do not contradict previous suggestions.     

Portable ladder assessment tool development and validation – Quantifying best practices in the field

Many causes for falls from ladders in construction are related to the user’s activities; however, the extent to which users comply with ladder use best practices is unknown and has not been well quantified before. We developed and tested an audit tool that assesses compliance with best practices guidelines for portable-ladder-use designed for applications in the construction industry. Implemented on a hand-held computer, the assessment tool consisted of a series of check-lists categorized in four groups; ladder condition, setup, moving on a ladder, and completing tasks from a ladder. For these four observational categories, the resulting tool contained 31 and 33 questions for step and extension ladders, respectively. Three individuals trained to use the tool scored a set of photographs and videos depicting 25 ladder conditions, 20 ladder setups, 10 users moving on ladders, and 13 users completing tasks from a ladder for a total of 78 observations. The assessment tool had good agreement across and within raters. For the three raters, agreement ranged from 79% to 97% across the questions. Within one subject, kappa coefficients for the intra-rater reliability ranged from 0.67 to 0.91. The tool offers a practical method to quantify best practices associated with ladder use that can ultimately inform targeted intervention efforts.     

A wind tunnel study of the effect of roadway configurations on the dispersion of traffic-related pollution

In this paper we examine the effect of different roadway configurations, including noise barriers and roadway elevation or depression relative to the surrounding terrain, on the dispersion of traffic-related pollutants for winds perpendicular to the roadway. A wind tunnel experiment modeling 12 different configurations was performed to study the flow fields and the concentration distributions resulting from emissions from a simulated six-lane highway. All of the configurations examined here reduced the downwind ground-level concentrations relative to that for a flat, unobstructed roadway; however, the degree to which the concentrations were reduced varied widely depending on the particular situation.Ground-level concentration data from the cases considered in this research indicate that a constant entrainment velocity can be used over the region beginning downwind of any initial disturbance to the flow resulting from the roadway configuration (e.g., a recirculation region behind a noise barrier) and extending at least to the end of our measurements. For example, for the case of a single noise barrier on the downwind side of the road, this region extends from approximately four barrier heights downwind of the roadway to 40 barrier heights. It was also found that the virtual origin concept is useful in describing the initial mixing created by the particular roadway configuration. To effectively model the influence of the roadway configuration on the dispersion, a combination of a virtual origin and an entrainment velocity may be effective. The magnitude of the virtual origin shift appears to depend on the particular roadway configuration, while the entrainment velocity appears to be a function of the friction velocity and the roadway geometry. These results suggest that road configuration must be taken into account in modeling near-road air quality.     

Wetlands mitigation: Partnership between an electric power company and a federal wildlife refuge

Nine hectares (23 acres) of a degraded section of Patuxent Research Refuge in Laurel, Maryland, USA, were converted to wetland habitat by the Baltimore Gas and Electric Company in 1994. The wetlands were created as mitigation for 5.7 ha (14 acres) of wetlands that were impacted as part of the construction of an 8.5-km (5.3-mile) 500-kV overhead transmission line on the refuge. The area consists of a created forested wetland of 5.5 ha (13.5 acres), a seasonally inundated green-tree reservoir of 7.6 ha (6.5 acres), and an impounded pond wetland of 1.2 ha (3 acres). Construction included the planting of 6131 trees, 4276 shrubs, and 15,102 emergent plants. Part of the site has been studied intensively since completion and survival of trees and shrubs after two years was 88%. Measurements of these transplants have shown growth greater than on other created sites in Maryland. Grasses and other herbaceous vegetation were dominant plants in the meter-square plots in the first two years of sampling of the created forested wetland. Wildlife surveys for birds, mammals, amphibians, and reptiles have revealed diverse communities. Although these communities represent species consistent with open habitat, more typical forest species should colonize the area as it undergoes succession into a more mature forested wetland. The creation, management, and research of this mitigation site represents an excellent example of a partnership between a private electric power company and a federal wildlife refuge. This partnership has increased local biodiversity and improved regional water quality of the Patuxent River and the Chesapeake Bay.     

SOIL EROSION AND GROUND WATER POLLUTION TRADEOFFS FOR NONIRRIGATED FARMING SYSTEMS1

ABSTRACT: Traditional focus on reducing one environmental externality may cause another externality to increase. This article examines the environmental and economic costs of abating soil loss and (or) nitrate leaching through alternative optimal production systems in the nonirrigated farming systems of Northeastern Oregon. Models estimating soil loss and nitrate‐nitrogen leaching rates associated with current production processes, are linked to a Multi‐Objective Programming (MOP) model. The results show that site specific conditions influence the level of abatement expenditures and optimal production strategies to reduce soil loss and leaching rates. Moreover, while existing production strategies are effective in reducing soil loss at little cost, no strategies could be identified to reduce nitrate leaching rate on some soils.