Natural attenuation of chlorinated ethene compounds: model development and field-scale application at the Dover site

A multi-dimensional and multi-species reactive transport model was developed to aid in the analysis of natural attenuation design at chlorinated solvent sites. The model can simulate several simultaneously occurring attenuation processes including aerobic and anaerobic biological degradation processes. The developed model was applied to analyze field-scale transport and biodegradation processes occurring at the Area-6 site in Dover Air Force Base, Delaware. The model was calibrated to field data collected at this site. The calibrated model reproduced the general groundwater flow patterns, and also, it successfully recreated the observed distribution of tetrachloroethene (PCE), trichloroethene (TCE), dichloroethylene (DCE), vinyl chloride (VC) and chloride plumes. Field-scale decay rates of these contaminant plumes were also estimated. The decay rates are within the range of values that were previously estimated based on lab-scale microcosm and field-scale transect analyses. Model simulation results indicated that the anaerobic degradation rate of TCE, source loading rate, and groundwater transport rate are the important model parameters. Sensitivity analysis of the model indicated that the shape and extent of the predicted TCE plume is most sensitive to transmissivity values. The total mass of the predicted TCE plume is most sensitive to TCE anaerobic degradation rates. The numerical model developed in this study is a useful engineering tool for integrating field-scale natural attenuation data within a rational modeling framework. The model results can be used for quantifying the relative importance of various simultaneously occurring natural attenuation processes.     

Spawning and development in <Emphasis Type="Italic">Osedax</Emphasis> boneworms (Siboglinidae,Annelida)

We report observations on spawning and early development in bone-eating worms of the genus Osedax. Individual females of Osedax rubiplumus were observed at 1820 m depth freely spawning hundreds of oocytes, and females of an undescribed species, Osedax “orange collar”, were observed spawning in laboratory aquaria. Cytological and molecular analysis of the spawned oocytes of two Osedax species revealed no evidence for the bacterial endosymbionts that the female worms require for their nutrition, suggesting that the bacteria must be acquired later from the environment, as they are in other siboglinids. Individual O. “orange collar” females released an average of 335 (±130) eggs per day, but the number of oocytes spawned per day varied greatly, suggesting that not all the females spawned daily. Fertilization rates of the spawned oocytes varied from 0 to 100%, though most females showed nearly 100% fertilization rates. Oocytes spawned in the laboratory at 4–6°C were negatively buoyant. If fertilized, these oocytes extruded polar bodies and then after at least four hours cleaved unequally. Subsequent cleavages occurred in a spiral pattern at roughly 2-h intervals, resulting in free-swimming trochophore larvae after 24 h. These lecithotrophic trochophores swam for 9–16 days before settling with several hooked chaetae, similar to those of dwarf Osedax males. The larval life span of the Osedax species studied in the laboratory appears to be shorter than in closely related Vestimentifera. Osedax rubiplumus, on the other hand, has much larger oocytes and so may have greater dispersal potential than these other Osedax species. The high fecundity and apparently continuous reproduction of Osedax boneworms permits the opportunistic exploitation of sunken vertebrate bones. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Repeated geographic divergence in behavior: a case study employing phenotypic trajectory analyses

Environmental effects on behavior have long been a focus of behavioral ecologists. Among the important drivers of behavior is predation environment, which can include the presence/absence of predators, differences in resource availability, and variation in individual density. Environments with predators are often more ecologically complex and “risky” than those without predators. Populations from these environments are sometimes more active and explorative than populations from low-risk, less complex environments. To date, most comparative studies of behavior are limited to within-species comparisons of populations from divergent environments, but neglect comparisons between species following speciation, thus limiting our understanding of post-speciation behavioral evolution. Brachyrhaphis fishes provide an ideal system for studying correlations between divergent environments and behavior within and between species. Here, we test for differences in two behavioral traits—activity and exploration —between sister species Brachyrhaphis roseni and Brachyrhaphis terrabensis that occur in divergent predation environments. Species differed in activity and exploration, with higher activity and exploration levels in populations that co-occur with predators. Furthermore, we found drainage-by-species interactions, indicating that the nature of divergence varied geographically. Using the recently developed phenotypic trajectory analysis (PTA), we quantified this difference and found that, while the geographically isolated populations of sister species tended to evolve in parallel, the magnitude of divergence between species differed between drainages. Our results highlight the utility of PTA for multivariate behavioral data and corroborate past predictions that complex and risky environments are correlated with increased activity and exploration levels and that divergence continues post-speciation.     

A case study of urban heat islands in the Carolinas

Urbanization tends to aggravate the negative effects of climate. The objective of this research is to aid in the understanding of the spatial variation of urban heat islands within selected cities in North and South Carolina. This understanding will help guide efforts to cool cities in order to increase human comfort, conserve energy and resources, and reduce air pollution in both of these states.     

Cognitive and affective identification: Exploring the links between different forms of social identification and personality with work attitudes and behavior

Individuals often identify with groups in order to either reduce perceived uncertainty or to feel better about who they are as individuals. This suggests that cognitive and affective identification are two distinctive forms of social identification in organizational settings. Because neurotic individuals are highly motivated to reduce perceived uncertainty, they will tend to identify cognitively with groups. Extraverted individuals, on the other hand, are highly motivated to enhance how they feel about themselves and thus identify affectively with groups. Across three studies, we develop measures of cognitive and affective identification and then show that neuroticism is positively related to cognitive identification, whereas extraversion is positively related to affective identification. We also find that affective identification provides incremental predictive validity over and above cognitive identification in the prediction of organizational commitment, organizational involvement, and organizational citizenship behaviors. Copyright © 2012 John Wiley & Sons, Ltd.     

Implications of dispersal and life history strategies for the persistence of Linyphiid spider populations

Linyphiid spiders have evolved the ability to disperse long distances by a process known as ballooning. It has been hypothesized that ballooning may allow populations to persist in the highly disturbed agricultural areas that the spiders prefer. In this study, I develop a stochastic population model to explore how the propensity for this type of long distance dispersal influences long term population persistence in a heterogeneous landscape where catastrophic mortality events are common. Analysis of this model indicates that although some dispersal does indeed decrease the probability of extinction of the population, the frequency of dispersal is only important in certain extremes. Instead, both the mean population birth and death rates, and the landscape composition, are much more important in determining the probability of extinction than the dispersal process. Thus, in order to develop effective conservation strategies for these spiders, better understanding of life history processes should be prioritized over an understanding of dispersal strategies.     

Effect of surfactants on persistence of azadirachtin-A (neem based pesticide)

Photostability of azadirachtin-A, a neem based pesticide, was studied in the presence of non-ionic surfactants. Surfactants such as Span-80, Atlox 3400B, Tween-80, Agrimul 52B, and Agrimul N4S enhanced the rate of photodegradation of azadirachtin-A, whereas surfactants such as Triton-X, Emulsol CFA, Tween-20, Emulsol MAS, and Emulsol-N-33 decreased the rate of degradation. Emulsol-N-33 was found to be the most effective surfactant, as half life of azadirachin-A in the presence of Emulsol-N-33 was found to be 94.93 min in comparison to 48 min for azadirachtin-A alone under UV light.     

Differences in accumulation of PAHs and metals on the leaves of Tiliaxeuchlora and Pyrus calleryana

The accumulation of substances associated with PM2.5 [polycyclic aromatic hydrocarbons (PAHs) and metals] on leaves of Pyrus calleryana (pear) and Tiliaxeuchlora (linden) along an urban road was investigated. These species have similar leaf morphology and were exposed to the identical environmental conditions. The accumulation of both PAHs and metals per leaf area was significantly higher on linden leaves than on pear leaves.     

A Note on the Emission of Nitrogen Oxides from Silage in Opened Bunker Silos

The evolution of NO_x from grass and maize silages wasmeasured using chemiluminescence in samples kept in airtightcontainers, in the silos and in a 750 kg mass removed to a mixer waggon. Measurements were made on the grass and maizesilos in two consecutive years. The results show that thereis continuous evolution of NO_x after silos have been opened and that high concentrations persist in the mass whichare rapidly released on agitation at the feed-out. The maximumrecorded concentrations of NO and NO₂ were 1985 and 152 ppbv respectively. These values are orders of magnitude greaterthan for rural background levels and exceed the maximum hourlyexposure of 50 ppbv for NO₂ recommended by the UK expertpanel for quality standards.