Tar Balls: The End State

Tar balls are frequently reported as an indicator of the extent of the impact of a spill incident. The determination of the density of tar balls is basic to the shoreline cleanup assessment team (SCAT) process, and is frequently used by the media as an indication of oil pollution. The processes involved in the evolution of tar balls are not well understood and there is a paucity of literature on the science of tar ball formation.     

Children's reasoning about poverty, physical deterioration, danger, and retribution in neighborhood contexts

This study examined children's moral, social and personal reasoning patterns about different neighborhood contexts. Three hundred and seventy-seven participants were selected from grades 2, 4, 6, and 8. Participants were shown 2 sets of photographs depicting the exact same houses and neighborhoods. One photograph displayed higher levels of physical incivilities and the other displayed higher levels of territoriality and place attachments. The vast majority of participants made strong social attributions of both danger and poverty towards physical contexts, depending on the level of incivilities depicted in the photographs. Moreover, an overwhelming majority gave justifications that fell into the moral domain. For most of the participants, the immorality of retribution overrode the negative attributions surrounding context. However, for those that approved of retribution behaviors, the physical setting appeared to influence their judgments. The findings suggest that the concept of extreme poverty (as represented by physical incivilities) and danger are fused at the cognitive level through linked interpretations of the same environmental cues.     

Composting of miscible cellulose acetate propionate-aliphatic polyester blends

A series of miscible blends consisting of cellulose acetate propionate (CAP) and poly(ethylene glutarate) (PEG) or poly(tetramethylene glutarate) (PTG) were evaluated in a static bench-scale simulated municipal compost environment. Samples were removed from the compost at different intervals, and the weight loss was determined before evaluation by gel permeation chromatography, scanning electron microscopy, and¹H NMR. The type of polyester (PEG versus PTG) in the blend made no difference in composting rates. At fixed CAP degree of substitution (DS), when the content of polyester in the blend was increased, the rate of composting and the weight loss due to composting increased. When the CAP was highly substituted, little degradation was observed within 30 days and almost all of the weight loss was ascribed to loss of polyester. Although the polyester was still observed to degrade faster, when the CAP DS was below approximately 2.0, both components are observed to degrade. The data suggests that initial degradation of the polyester is by chemical hydrolysis and the rate of this hydrolysis is very dependent upon the temperature profile of the compost and upon the DS of the CAP.     

Intensity of territorial defense in red squirrels: an experimental test of the asymmetric war of attrition

Summary Red squirrels defend exclusive, individual territories year round, 20% to 50% of females do not breed in any given year, and breeding females raise juveniles on their territories. Breeding is asynchronous, and the offspring of early-breeding females are more likely to hold an independently won territory than are late-born offspring. Based on the asymmetric war of attrition, we made the following predictions: (1) squirrels would respond more intensely to the calls of unfamiliar individuals than to the calls of neighbors; (2) breeding females would respond more intensely to unknown calls than would non-breeding females or males; (3) early-breeding females would respond more intensely than would late-breeding females to unknown calls; and (4) all classes of squirrels would respond similarly to the calls of neighbors. Playback experiments supported the predictions. Alternative hypotheses of kin selection, risk of infanticide, and seasonal difference in intruder pressure could not explain the results.     

Design and Verification of a Programmable Gas Dispensing System for Exposing Plants to Dynamic Concentrations of Air Pollutants

Abstract

Landfills represent a source of distributed emissions source over an irregular and heterogeneous surface. In the method termed “Other Test Method-10” (OTM-10), the U.S. Environmental Protection Agency (EPA) has proposed a method to quantify emissions from such sources by the use of vertical radial plume mapping (VRPM) techniques combined with measurement of wind speed to determine the average emission flux per unit area per time from nonpoint sources. In such application, the VRPM is used as a tool to estimate the mass of the gas of interest crossing a vertical plane. This estimation is done by fitting the field-measured concentration spatial data to a Gaussian or some other distribution to define a plume crossing the vertical plane. When this technique is applied to landfill surfaces, the VRPM plane may be within the emitting source area itself. The objective of this study was to investigate uncertainties associated with using OTM-10 for landfills. The spatial variability of emission in the emitting domain can lead to uncertainties of –34 to 190% in the measured flux value when idealistic scenarios were simulated. The level of uncertainty might be higher when the number and locations of emitting sources are not known (typical field conditions). The level of uncertainty can be reduced by improving the layout of the VRPM plane in the field in accordance with an initial survey of the emission patterns. The change in wind direction during an OTM-10 testing setup can introduce an uncertainty of 20% of the measured flux value. This study also provides estimates of the area contributing to flux (ACF) to be used in conjunction with OTM-10 procedures. The estimate of ACF is a function of the atmospheric stability class and has an uncertainty of 10–30%.