Genetic evidence for mixed parentage in nests of the emu (Dromaius novaehollandiae)

Parentage in emus (Dromaius novaehollandiae) was examined by microsatellite analysis using four independent loci. Of 106 chicks sampled in one breeding season from 18 nests, 54 (51%) were not fathered by the nesting male, 12 (11%) were not from the observed mate of the sitting male, and 9 (8%) represented intra-specific brood parasitism, having no alleles in common with either nest parent. Some males (11%) fathered all chicks in their nests, but the majority showed high levels of cuckoldry. Those males commencing incubation earliest in the season tended to have the highest levels of paternity in their own nests. These results reveal a high frequency of extra-pair fertilisations and resultant cuckoldry in a predominantly socially monogamous bird and support recent reports which have described the emu mating system as a complexity of polyandrous, promiscuous and monogamous behaviour. Parentage assignment of chicks resulting from extra-pair fertilisations revealed an evenly scattered pattern of paternity that did not show any particular male dominance in reproductive success. These results lead to a reassessment of behavioural observations of emus, the consequences of parentage distribution, and theories about mating systems and sexual selection. The frequency of extra-pair copulations and intra-specific brood parasitism suggests patterns of descent that differ greatly from those implied by social monogamy. Received: 27 November 1999 / Received in revised form: 8 January 2000 / Accepted: 8 February 2000     

Flood management: prediction of microbial contamination in large-scale floods in urban environments

With a changing climate and increased urbanisation, the occurrence and the impact of flooding is expected to increase significantly. Floods can bring pathogens into homes and cause lingering damp and microbial growth in buildings, with the level of growth and persistence dependent on the volume and chemical and biological content of the flood water, the properties of the contaminating microbes, and the surrounding environmental conditions, including the restoration time and methods, the heat and moisture transport properties of the envelope design, and the ability of the construction material to sustain the microbial growth. The public health risk will depend on the interaction of these complex processes and the vulnerability and susceptibility of occupants in the affected areas. After the 2007 floods in the UK, the Pitt review noted that there is lack of relevant scientific evidence and consistency with regard to the management and treatment of flooded homes, which not only put the local population at risk but also caused unnecessary delays in the restoration effort. Understanding the drying behaviour of flooded buildings in the UK building stock under different scenarios, and the ability of microbial contaminants to grow, persist, and produce toxins within these buildings can help inform recovery efforts. To contribute to future flood management, this paper proposes the use of building simulations and biological models to predict the risk of microbial contamination in typical UK buildings. We review the state of the art with regard to biological contamination following flooding, relevant building simulation, simulation-linked microbial modelling, and current practical considerations in flood remediation. Using the city of London as an example, a methodology is proposed that uses GIS as a platform to integrate drying models and microbial risk models with the local building stock and flood models. The integrated tool will help local governments, health authorities, insurance companies and residents to better understand, prepare for and manage a large-scale flood in urban environments.     

Urban–rural differences in atmospheric mercury speciation

Measurements of gaseous elemental mercury (GEM), particulate mercury (Hg_p), and reactive gaseous mercury (RGM) were concurrently recorded at an urban site in Detroit and a rural site in Dexter, both in Michigan for the calendar year 2004. Their average concentrations (±standard deviation) for the urban area were 2.5 ± 1.4 ng m^?3, 18.1 ± 61.0 pg m^?3, and 15.5 ± 54.9 pg m^?3, respectively, while their rural counterparts were 1.6 ± 0.6 ng m^?3, 6.1 ± 5.5 pg m^?3, and 3.8 ± 6.6 pg m^?3, respectively. The medians of urban-to-rural ratios of Hg concentrations indicate approximately 1-fold, 2-fold, and 3-fold gradients between Detroit and Dexter for GEM, Hg_p, and RGM, respectively. The urban–rural differences in Hg also varied considerably on different temporal scales and with wind flow patterns, which was most evident in RGM. Our results show that while Hg at both sites was impacted by regional sources, meteorological conditions, and photochemical transformations, the extent of variations in the observed urban-to-rural gradients, particularly in RGM, cannot be fully accounted for by these processes. Both analyses of the annual data and case studies indicate that the more variable and episodic nature of Hg, particularly RGM, seen in Detroit compared with Dexter, was the result of direct impact from local anthropogenic sources.     

Mathematical model for photocatalytic destruction of organic contaminants in air

Photocatalytic oxidation (PCO) was investigated in a bench-scale reactor for the abatement of two airborne organic contaminants: toluene and ethanol. A mathematical model that includes the impacts of light intensity, initial contaminant concentration, catalyst thickness, and relative humidity (RH) on the degradation of organic contaminants in a photocatalytic reactor was developed to describe this process. The commercially available catalyst Degussa-PtTiO2 was selected to compare with the MTU-PtTiO2-350 catalyst, which was synthesized by the sol-gel process, platinized, and calcined at 350 degrees C. For toluene removal using the MTU-PtTiO2-350 catalyst, the degradation rate increased with increases in light intensity from 0.2 to 2.2 mW/cm2 and in catalyst thickness from 0.00037 to 0.00361 cm. However, further increases in light intensity and catalyst thickness had only slight effect on the toluene degradation rate. Increasing the initial concentration from 6.29 to 127.9 microg/L and the RH from 10 to 85% resulted in decreases in the toluene degradation rate. For ethanol removal using the MTU-PtTiO2-350 catalyst, the degradation rate increased more rapidly with an increase in RH from 17 to 56%; the RH had little effect on the ethanol degradation rate while it further increased from 56% to 82%. We discuss applicability of the model to estimate the influence of process variables and to evaluate photocatalyst performance.     

Initiation and resolution of jumping spider contests: roles for size, proximity, and early detection of rivals

Animals are commonly expected to assess each other during contests in order to economically identify relative status. Escalated or long contests are expected to arise mainly when rivals have difficulty discriminating small differences. Results of the present study of male-male contests in Plexippus paykulli, a jumping spider (Salticidae) with acute vision, are not in accord with this widely held view. Despite the typical finding that size-advantaged rivals are more likely to win contests and that this tendency increases with size disparity, contest dynamics suggest that these tendencies are achieved in the absence of direct size assessment. In contests between different-sized spiders, maximum escalation and overall duration were predicted by the absolute size of the size-disadvantaged spider (usually the loser) rather than the size difference between the rivals. This result suggests that spiders base decisions of persistence on their own size, such that size-disadvantaged rivals usually reach their limits first, and then retreat. This interpretation is further supported by findings that maximum escalation and total duration were both positively related to size in contests between size-matched spiders. Spiders were more likely to win if they oriented and displayed first, and longer, more escalated, contests ensued if the size-disadvantaged spider was the first to orient and display. Proximity of rivals at contest outset also influenced contest dynamics, but not outcome.     

Evaluation of the MIDTAL microarray chip for monitoring toxic microalgae in the Orkney Islands, U.K.

Harmful or nuisance algal blooms can cause economic damage to fisheries and tourism. Additionally, toxins produced by harmful algae and ingested via contaminated shellfish can be potentially fatal to humans. The seas around the Orkney Islands, UK currently hold a number of toxic algal species which cause shellfishery closures in most years. Extensive and costly monitoring programs are carried out to detect harmful microalgae before they reach action levels. However, the ability to distinguish between toxic and non-toxic strains of some algae is not possible using these methods. The microarrays for the detection of toxic algae (MIDTAL) microarray contains rRNA probes for toxic algal species/strains which have been adapted and optimized for microarray use. In order to investigate the use of the chip for monitoring in the Orkney Islands, samples were collected between 2009 and 2011 from Brings Deep, Scapa Flow, Orkney Islands, UK; RNA was extracted and hybridized with generation 2 and 3.1 of the chip. The data were then compared to cell counts performed under light microscopy and in the case of Alexandrium tamarense to qPCR data targeting the saxitoxin gene and the LSU-rRNA gene. A good agreement between cell numbers and microarray signal was found for A. tamarense, Pseudo-nitzschia sp., Dinophysis sp. (r?<?0.5, for all) in addition to this there the chip successfully detected a large bloom of Karenia mikimotoi (r?<?0.70) in August and September 2011. Overall, there was good improvement in probe signal between generation 2 and generation 3.1 of the chip with much less variability and more consistent results and better correlation between the probes. The chip performed well for A. tamarense group I signal to cell numbers in calibrations (r?>?0.9). However, in field samples, this correlation was slightly lower suggesting interactions between all species in the sample may affect signal. Overall, the chip showed it could identify the presence of target species in field samples although some work is needed to improve the quantitative nature of the chip before it would be suitable for monitoring in the Orkney Islands.     

Fluorocarbons in the Los Angeles Basin

Ambient air concentrations of fluorocarbon 11 (fluorotrichloromethane) and fluoro-carbon 12 (dichlorodifluoromethane) have been measured using a gas chro-matograph equipped with a pulsed, electron capture detector. Air samples taken on a moderately smoggy day in July 1970, at several locations near Los Angeles gave average readings of fluorocarbon 12, 0.7 ppb and fluorocarbon 11, 0.56 ppb. These readings were contrasted with those taken in early February 1973 when the air was clear and marked with turbulence due to several seasonal rain storms. The readings of both fluorocarbon 1 1 and 12 averaged about 25% less during clear weather than those taken during moderate smog. The effects of weather conditions on the concentration were also dramatically pointed out by the February samples, in that as much as a tenfold change in concentrations of both fluorocarbons from location to location and from day to day at the same location was observed. A concentration versus altitude study clearly revealed that fluorocarbons are trapped by an inversion layer. Examination of air samples taken in the vicinity of factories known to be users of fairly large quantities of fluorocarbons revealed in part how large users contribute to the atmospheric concentrations of fluorocarbons. A comparison of fluorocarbon levels in homes and public buildings with ambient outside air levels revealed that the concentrations in some homes and buildings may be as much as several thousand times as high as levels in outside air. Inside the homes and public buildings, levels were as high as one-half of a part per million. Long term photolysis studies in simulated sunlight of both fluorocarbons 11 and 12 in ambient air samples and in air samples with 1 ppm of hydrocarbon and 1 ppm of nitrogen oxides revealed that the two fluorocarbons are photochemically stable even when photolyzed for several weeks.     

Sulfur Hexafluoride as a Surrogate for Monitoring Hazardous Waste Incinerator Performance

A viable chemical surrogate for monitoring the effectiveness of hazardous waste incinerators must include high thermal stability and low toxicity among its characteristics. The relationship between sulfur hexafluoride (SF₆) and hazardous constituent thermal stability for a mixture of chlorinated hydrocarbons indicates that SF6 has the potential to satisfy the basic requirements of a chemical surrogate for hazardous waste incineration.     

Modeling of Indoor Air Treatment of Polychlorinated Dibenzo-p-Dioxins and Dibenzofurans Using High-Efficiency Particulate Air-Carbon Filtration

Abstract

A high-efficiency particulate air (HEPA)-carbon filtration system was developed by the Access Business Group, LLC, to reduce the indoor levels of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs). The HEPA filter removes the particle-bound PCDD/Fs, and the carbon filter removes the gaseous fraction. Because of the toxicity of PCDD/Fs, it is very difficult to handle them in the laboratory. In this study, mathematical modeling was performed to evaluate the performance of the HEPA-carbon filtration system for PCDD/Fs removal and to optimize its design and operation. The model was calibrated with experimental data conducted with toluene in a sealed room. Model simulations with four selected congeners demonstrated that it takes ～1 hr for the indoor air treatment system to reach the maximum removal efficiency and that the carbon air filter has a life time of 10⁷ yr for dioxin removal. Given a zero emission from the HEPA filter, the overall removal efficiency is 78.7% for 2,3,7,8-tetrachloro dibenzo-p-dioxins, 89.8% for octa-chlorodibenzodioxin, 78% for tetra-chlorodibenzofuran, and 89.8% for octachlorodibenzofuran. The larger the mass emission from the HEPA filter, the lower the overall removal efficiency, and the larger the ratio of the filter flow rate (Q_f) to the room flow rate (Q), the higher the overall removal efficiency. When the ratio of Q_f/Q is 15, an overall removal efficiency of 90% can be reached for all four of the selected compounds. The removal of the four selected compounds does not change as the relative humidity increases ≤90%.     

Technology Innovations and Experience Curves for Nitrogen Oxides Control Technologies

Abstract

This paper reviews the regulatory history for nitrogen oxides (NO_x) pollutant emissions from stationary sources, primarily in coal-fired power plants. Nitrogen dioxide (NO₂) is one of the six criteria pollutants regulated by the 1970 Clean Air Act where National Ambient Air Quality Standards were established to protect public health and welfare. We use patent data to show that in the cases of Japan, Germany, and the United States, innovations in NO_x control technologies did not occur until stringent government regulations were in place, thus “forcing” innovation. We also demonstrate that reductions in the capital and operation and maintenance (O&M) costs of new generations of high-efficiency NO_x control technologies, selective catalytic reduction (SCR), are consistently associated with the increasing adoption of the control technology: the so-called learning-by-doing phenomena. The results show that as cumulative world coal-fired SCR capacity doubles, capital costs decline to ~86% and O&M costs to 58% of their original values. The observed changes in SCR technology reflect the impact of technological advance as well as other factors, such as market competition and economies of scale.