Genotoxicity of oxy-PAHs to Japanese medaka (Oryzias latipes) embryos assessed using the comet assay

Polycyclic aromatic hydrocarbons (PAHs) have long been recognized as important environmental toxicants. Despite a plethora of information on the fate and effects of parent PAHs, relatively little is known about the environmental fate and toxicity of ketone- and quinone-substituted PAH oxidation products (termed oxy-PAHs), particularly in the aquatic environment. This study begins to fill that gap using embryos of the Japanese medaka (Oryzias latipes) as a model species. The genotoxic potential of two environmentally relevant oxy-PAHs, acenaphthenequinone and 7,12-benz[a]anthracenquinone, was assessed using the comet assay. We found that both oxy-PAHs could cause significant increases in DNA damage after only 48 h of exposure at the lowest concentrations tested (5 μg/L). Comparisons of the genotoxic potential between these oxy-PAHs and their corresponding parent PAHs (acenaphthene and benz[a]anthracene) and a well-known mutagenic PAH, benzo[a]pyrene, indicated similar potencies among all five of these compounds, particularly after longer (7 day) exposures. This study demonstrates the mutagenic potential of oxy-PAHs to an in vivo fish embryo model and points out the need for further study of their environmental occurrence and biologic effects.     

The safety observer effect: the effects of conducting safety observations

INTRODUCTION: Some research suggests that conducting safety observations of another's safety performance may serve as an effective tool in increasing the safety performance of the observer. The primary purpose of the present study was to assess the effects of conducting safety observations on the postural safety performance of observers engaging in an assembly task for short time periods. The secondary objectives of the study were: (a) to measure productivity, and (b) to measure the accuracy of participant safety observations. METHOD: An ABC (A: baseline, B: information, C: observation) multiple-baseline design counterbalanced across postural behaviors (back, shoulder, and feet position) was implemented with six participants. RESULTS AND DISCUSSION: Substantial improvements in postural safety occurred after participants conducted safety observations, and these improvements did not appear to negatively affect productivity. Results also suggest that there is no relation between the accuracy of an observer's safety observation and their subsequent safety performance. IMPACT ON INDUSTRY: This research provides evidence that a safety observation process can function to increase safe postural behavior of observers. Thus, the implementation of such a process may contribute to the prevention of musculoskeletal disorders and related costs in the workplace.     

Modeling Residential Lawn Fertilization Practices: Integrating High Resolution Remote Sensing with Socioeconomic Data

This article investigates how remotely sensed lawn characteristics, such as parcel lawn area and parcel lawn greenness, combined with household characteristics, can be used to predict household lawn fertilization practices on private residential lands. This study involves two watersheds, Glyndon and Baisman’s Run, in Baltimore County, Maryland, USA. Parcel lawn area and lawn greenness were derived from high-resolution aerial imagery using an object-oriented classification approach. Four indicators of household characteristics, including lot size, square footage of the house, housing value, and housing age were obtained from a property database. Residential lawn care survey data combined with remotely sensed parcel lawn area and greenness data were used to estimate two measures of household lawn fertilization practices, household annual fertilizer nitrogen application amount (N_yr) and household annual fertilizer nitrogen application rate (N_ha_yr). Using multiple regression with multi-model inferential procedures, we found that a combination of parcel lawn area and parcel lawn greenness best predicts N_yr, whereas a combination of parcel lawn greenness and lot size best predicts variation in N_ha_yr. Our analyses show that household fertilization practices can be effectively predicted by remotely sensed lawn indices and household characteristics. This has significant implications for urban watershed managers and modelers.     

Assessing the aerobic biodegradability of 14 hydrocarbons in two soils using a simple microcosm/respiration method.

The aerobic biodegradability of 14 hydrocarbons in two soils was determined using a simple microcosm/respirometric method based on oxygen consumption. Biodegradability was assessed indirectly by measuring the depletion of oxygen over time in the headspace of microcosms containing soil and test chemicals. The microcosms consisted of small glass vials fitted with valves that allowed headspace gas samples to be collected, essentially resulting in a sealed system. Respiration data from control microcosms were obtained from identically treated microcosms with no test chemical. Control data were necessarily included in all calculations of percent of theoretical oxygen demand (%ThOD) for any given test chemical. Two experiments were performed to verify this simple biodegradation test method. First, an experiment was performed in which disappearance of n-tetradecane from the microcosms was measured directly by standard soil extraction and analytical techniques while simultaneously performing this simple respirometric method based on %ThOD with the same test chemical. Second, the method was compared to a well-established radiochemical technique using 14C-phenanthrene. Results of both comparisons showed that the method is both accurate and reliable. The consistent manner with which the data were produced in two different soils show that the method is also very reproducible. The method described here provides a simple and inexpensive method for determining the aerobic biodegradability of organic compounds in soils.     

Congo Basin peatlands: threats and conservation priorities

Mitigation and Adaptation Strategies for Global Change - The recent publication of the first spatially explicit map of peatlands in the Cuvette Centrale, central Congo Basin, reveals it to be the...     

Analysis and Predictive Models of Single‐Family Customer Response to Water Curtailments During Drought1

Polebitski, Austin S. and Richard N. Palmer, 2012. Analysis and Predictive Models of Single‐Family Customer Response to Water Curtailments During Drought. Journal of the American Water Resources Association (JAWRA) 1‐12. DOI: 10.1111/j.1752‐1688.2012.00691.x Abstract: This research investigates customer response to demand management strategies during two drought periods in the City of Seattle. An analysis of customer response to voluntary water curtailments is conducted using k‐means clustering to identify like groups of customers and behavior patterns. The clustering method identified important variables (household income, lot size, living space, and family size) useful in determining customer response to water curtailments. Ordinary least squares and spatial lag regression models are estimated using the first and second principal components of variables identified in the clustering analysis. Larger values of income, lot size, and living space enhanced water reductions whereas larger family size tended to reduce the effectiveness of curtailments. Projections of changes in Seattle’s built environment and demographics between 2000 and 2030 were obtained from an urban simulation model (UrbanSim) and were processed through the regression models to investigate changes in future curtailment effectiveness. This research found that increasing household size hardened demands (decreased curtailment effectiveness) whereas decreasing household size increased per‐capita curtailment effectiveness. These results suggest that changes in the number of residents within a home is likely to be the most important factor in determining future curtailment effectiveness.     

Maternal transfer of mercury to the developing embryo/fetus: is there a safe level?

Mercury (Hg) exposure is ubiquitous in modern society via vaccines, fish/crustacea, dental amalgam, food, water, and the atmosphere. This article examines Hg exposure in the context of primary exposure to pregnant women and secondary exposure experienced by their unborn babies. Babies in utero are particularly at risk of higher Hg exposure than adults (on a dose/weight basis through maternal Hg transfer via the placenta), and are more susceptible to adverse effects from mercury and its biologically active compounds. It is, therefore, critical that regulatory advisories around maximum safe Hg exposures account for pregnant women and secondary exposure that children in utero experience. This study focused on standardized embryonic and fetal Hg exposures via primary exposure to the pregnant mother of two common Hg sources (dietary fish and parenteral vaccines). Data demonstrated that Hg exposures, particularly during the first trimester of pregnancy, at well-established dose/weight ratios produced severe damage to humans including death. In light of research suggestive of a mercuric risk factor for childhood conditions such as tic disorders, cerebral palsy, and autism, it is essential that Hg advisories account for secondary prenatal human exposures.     

Raising awareness of transport issues: The potential to bring about behavioural change?

Changes in the directions of transport policy in the UK in the last few years have led to a wider consideration of possible measures to bring about behavioural change, in particular measures which have the potential to reduce car dependence. Among the measures currently being implemented by local authorities are public awareness or travel awareness campaigns. This paper examines the findings of a research project which evaluated a travel awareness scheme in the context of an integrated transport policy. The research project monitored the attitudes, beliefs and intentions of a sample of the residents who had been targeted by the Maidstone Initiative for Sustainable Transport (MIST) implemented by Kent County Council and Maidstone Borough Council. The research project found some remarkably consistent attitudes about car and bus travel over a period of three years, It also found that whilst people seem to be aware of the impact of travel on the environment they do not consider the environmental impact with the same degree of importance as other attributes of travel. A further finding was a hidden desire to switch modes from the car. The paper will conclude by looking critically at the future for travel awareness campaigns.     

Response of sea urchin pluteus larvae (Echinodermata: Echinoidea) to reduced seawater pH: a comparison among a tropical, temperate, and a polar species

Ocean acidification, as a result of increased atmospheric CO₂, is predicted to lower the pH of seawater to between pH 7.6 and 7.8 over the next 100 years. The greatest changes are expected in polar waters. Our research aimed to examine how echinoid larvae are affected by lower pH, and if effects are more pronounced in polar species. We examined the effects of lowered pH on larvae from tropical (Tripneustes gratilla), temperate (Pseudechinus huttoni, Evechinus chloroticus), and a polar species (Sterechinus neumayeri) in a series of laboratory experiments. Larvae were reared in a range of lower pH seawater (pH 6.0, 6.5, 7.0, 7.5, 7.7, 7.8 and ambient), adjusted by bubbling CO₂ gas. The effect of pH on somatic and skeletal growth, calcification index, development and survival were quantified, while SEM examination of the larval skeleton provided information on the effects of seawater pH on the fine-scale skeletal morphology. Lowering pH resulted in a decrease in survival in all species, but only below pH 7.0. The size of larvae were reduced at lowered pH, but the external morphology (shape) was unaffected. Calcification of the larval skeleton was significantly reduced (13.8–36.9% lower) under lowered pH, with the exception of the Antarctic species, which showed no significant difference. SEM examination revealed a degradation of the larval skeletons of Pseudechinus and Evechinus when grown in reduced pH. Sterechinus and Tripneustes showed no apparent difference in the skeletal fine structure under lowered pH. The study confirms the need to look beyond mortality as a single endpoint when considering the effects of ocean acidification that may occur through the 21st century, and instead, look for a suite of more subtle changes, which may indirectly affect the functioning of larval stages.