Temporal analysis of airborne particulate matter reveals a dose-rate effect on mortality in El Paso: indications of differential toxicity for different particle mixtures

One of two topics explored is the limitations of the daily average in summarizing pollutant hourly profiles. The daily average of hourly measurements of air pollutant constituents provides continuity with previous studies using monitoring technology that only provided the daily average. However, other summary statistics are needed that make better use of all available information in 24-hr profiles. The daily average reflects the total daily dose, obscuring hourly resolution of the dose rate. Air pollutant exposures with comparable total daily doses may have very different effects when occurring at high levels over a few hours as opposed to low levels over a longer time. Alternative data-based choices for summary statistics are provided using principal component analysis to capture the exposure dose rate, while preserving ease of interpretation. This is demonstrated using the earliest hourly particle concentration data available for El Paso from archived records of particulate matter (PM)10. In this way, a significant association between evening PM10 exposures and nonaccidental daily mortality is found in El Paso from 1992 to 1995, otherwise missed using the daily average. Secondly, the nature and, hence, effects of particles in the ambient aerosol during El Paso sandstorms is believed different from that of particles present during still-air conditions resulting from atmospheric temperature inversions. To investigate this, wind speed (ws) is used as a surrogate variable to label PM10 exposures as Low-ws (primarily fine particles), High-ws (primarily coarse particles), or Mid-ws (a mixture of fine and coarse particles). A High-ws evening is significantly associated with a 10% lower risk of mortality on the succeeding third day, as compared with comparable exposures at Low- or Mid-ws. Although this analysis cannot be used to form firm conclusions because it uses a very small data set, it demonstrates the limitations of the daily average and suggests differential toxicity for different particle compositions.     

Modeling tracer diffusion in fractured and unfractured, unsaturated, porous media

A proposed tracer diffusion test for the Exploratory Shaft Facility at Yucca Mountain, NV, is modeled. For the proposed test, a solution containing conservative tracers will be introduced into a borehole in the geologic medium of interest. The tracers will diffuse and advect from the saturated source region into the unsaturated matrix in the surrounding tuff. After some time, the borehole is to be overcored, and tracer concentrations in the fluid will be measured in the core as a function of distance from emplacement. The data will be used to evaluate diffusive behavior and to derive effective diffusion coefficients for the tracers in the specific tuff. Numerical simulations are used to study the effects of effective diffusion coefficient, porosity, saturation, and fracturing on tracer transport. Results are reported for numerical simulations of tests in the Topopah Spring Member and the Tuff of Calico Hills, which have significantly different porosities and saturations. The simulations make the following predictions: The spread of tracer during the test will be sensitive to the effective diffusion coefficient of the tracer. Tracer will diffuse farther in the Topopah Spring Member than in the Tuff of Calico Hills because of the former's lower porosity and saturation. Tracer transport by advection into the Topopah Spring Member will be greater than that into the Tuff of Calico Hills because of capillary effects. While advection will be a significant mechanism for tracer penetration into the Topopah Spring tuff, it will be less significant for tracer penetration into the Calico Hills tuff. The proximity of a single vertical fracture to the source region determines its effects on tracer transport, especially if the fracture diverts fluid flowing from the source region into the matrix.     

Integrated assessment modeling of atmospheric pollutants in the Southern Appalachian Mountains. Part I: hourly and seasonal ozone

Recently, a comprehensive air quality modeling system was developed as part of the Southern Appalachians Mountains Initiative (SAMI) with the ability to simulate meteorology, emissions, ozone, size- and composition-resolved particulate matter, and pollutant deposition fluxes. As part of SAMI, the RAMS/EMS-95/URM-1ATM modeling system was used to evaluate potential emission control strategies to reduce atmospheric pollutant levels at Class I areas located in the Southern Appalachians Mountains. This article discusses the details of the ozone model performance and the methodology that was used to scale discrete episodic pollutant levels to seasonal and annual averages. The daily mean normalized bias and error for 1-hr and 8-hr ozone were within U.S. Environment Protection Agency guidance criteria for urban-scale modeling. The model typically showed a systematic overestimation for low ozone levels and an underestimation for high levels. Because SAMI was primarily interested in simulating the growing season ozone levels in Class I areas, daily and seasonal cumulative ozone exposure, as characterized by the W126 index, were also evaluated. The daily ozone W126 performance was not as good as the hourly ozone performance; however, the seasonal ozone W126 scaled up from daily values was within 17% of the observations at two typical Class I areas of the SAMI region. The overall ozone performance of the model was deemed acceptable for the purposes of SAMI's assessment.     

Female choice and the evolution of the conspicuous plumage coloration of monogamous male great tits

Summary The conspicuous male plumage coloration of many avian species is often regarded as the result of sexual selection through female choice. In general terms such plumage characters may evolve in monogamous species if males bearing them pair with high quality females and so reproduce more successfully than males lacking the character. Male great tits have a conspicuous, central black breast stripe which varies in size between individuals. The stripe is also present in the female although it is smaller in size. Male great tits with large stripes paired with females which laid large clutches. Furthermore, in one of three years, females paired with such males commenced breeding earlier in the season than other females. Individual females were significantly more consistent in their clutch size and laying date between years than were nesting boxes. Males with large stripes paired with females which had previously laid a large clutch. Although there was evidence that territory quality may affect female reproductive success by influencing nesting success and nestling quality, there was no significant relationship between the stripe size of a male and the quality of his territory. Therefore, the results suggest that female great tits are choosing the characteristics of the male rather than the quality of his territory. The evidence thus suggests that female choice may be important in the evolution of male secondary sexual characteristics in great tits.     

Antioxidant alteration ofGlycine max (Fabaceae) defensive chemistry: Analogy to herbivory elicitation

Summary The water-soluble antioxidant, L-ascorbic acid (vitamin C), proved elicitory to alterable anti-herbivory inGlycine max againstTrichoplusia ni larvae. Elicitation by vitamin C was influenced especially by dose, time after elicitation and space in the plant. Results allow an analogy between antioxidant and herbivory elicitation. Elicitation apparently involves a sulfhydryl-protein-dependent redox mechanism which can be significantly affected by antioxidants. Findings would also support a proposed common redox-based mechanism, involving the plasma membrane, for communication between plant and animal cells and their environments.     

Recovery of sulfate saturated soils in the Plynlimon catchments, mid-Wales following reductions in atmospheric S inputs from the 1980s to 2011

Sulfate adsorption capacity of B-horizons of base-poor, predominantly stagnopodzol, soils from the Plynlimon catchments, mid-Wales was determined by combination of laboratory adsorption and desorption isotherms. Results show that sulfate adsorption capacity of a range of stagnopodzol (Histic-stagno-podzol (Leptic), WRB), brown podzolic soil (Histic-umbrisol (Leptic), WRB) and stagnohumic gley (Histic-stagno-gleysol, WRB) B-horizons was positively related to the amounts of extractable (pyrophosphate and oxalate) Fe + Al, with the stagnopodzol and brown podzolic soil Bs horizon having the largest adsorption capacity and stagnohumic gley Bg horizon the smallest adsorption capacity. Results show that dissolved organic carbon (DOC) has a negative but limited effect on sulfate adsorption in these soils. Results obtained from a set of historical soil samples revealed that the grassland brown podzolic soil Bs horizon and afforested stagnopodzol Bs horizon were highly saturated with sulfate in the 1980s, at 63% and 89% respectively, whereas data from some recently sampled soil from two sites revisited in 2010-11 indicates that percentage sulfate adsorption saturation has since fallen substantially, to 41% and 50% respectively. Between 1984 and 2009 the annual rainfall-weighted mean excess SO(4)-S concentration in bulk precipitation declined linearly from 0.37 mg S l(-1) to 0.17 mg S l(-1). Over the same period, flow weighted annual mean stream water SO(4)-S concentrations decreased approximately linearly from 1.47 mg S l(-1) to 0.97 mg S l(-1) in the plantation afforested Hafren catchment compared to a drop from 1.25 to 0.69 mg S l(-1) in the adjacent moorland catchment of the Afon Gwy. In flux terms, the mean decrease in annual stream water SO(4)-S flux has been approximately 0.4 kg S ha(-1) yr(-1), whilst the recovery in stream water quality in the Afon Cyff grassland catchment has been partly offset by loss of SO(4)-S by desorption from the soil sulfur pool of approximately 0.2 kg S ha(-1) yr(-1).     

The design of child restraint system (CRS) labels and warnings affects overall CRS usability

A study was conducted that assessed the effectiveness of different child restraint system (CRS) label/warning designs on users' installation performance. Forty-eight paid participants installed a convertible CRS in a vehicle, and two child test dummies in a CRS, using one of four label conditions. The label conditions were: (1) no labels, (2) the manufacturer's labels that were already affixed to the CRS ("Current"), (3) labels that were designed according to a combination of the current U.S. regulations concerning CRS labels and recently proposed changes to these regulations ("Proposed"), and (4) labels that were designed according to human factors principles and guidelines, and that were based on a hierarchical behavioral task analysis ("Optimal"). Results demonstrated that, overall, the Optimal labels resulted in higher usability ratings and better task performance. This indicates that labels designed using human factors and task analyses that identify critical task information requirements for label features will result in increased user compliance with instructions, higher usability, and improved task performance. Surprisingly, having no labels on the CRS resulted in better installation performance than when either the Current or the Proposed label conditions were used. This indicates that label design can decrease task performance; the actual physical design of a CRS may be just as critical as label content in the installation choices provided to the user. Collectively, results suggest that implementation of the proposed changes to the U.S. regulations concerning CRS labeling would likely not result in increased performance or usability compared to existing manufacturer labels that follow the current guidelines. In order to achieve significantly better ease-of-use and task performance, it would be necessary to implement features of the Optimal label condition.     

Integrating Economic Analysis into LCA

Current life‐cycle assessment (LCA) methodologies rarely include economic analysis—even though this element is almost always crucial to any company's decision making. This article discusses practical tools for integrating economic considerations into LCA. © 2001 John Wiley & Sons, Inc.