Empirical evaluation of spatial and non-spatial European-scale multimedia fate models: results and implications for chemical risk assessment

Multimedia environmental fate models are commonly-applied tools for assessing the fate and distribution of contaminants in the environment. Owing to the large number of chemicals in use and the paucity of monitoring data, such models are often adopted as part of decision-support systems for chemical risk assessment. The purpose of this study was to evaluate the performance of three multimedia environmental fate models (spatially- and non-spatially-explicit) at a European scale. The assessment was conducted for four polycyclic aromatic hydrocarbons (PAHs) and hexachlorobenzene (HCB) and compared predicted and median observed concentrations using monitoring data collected for air, water, sediments and soils. Model performance in the air compartment was reasonable for all models included in the evaluation exercise as predicted concentrations were typically within a factor of 3 of the median observed concentrations. Furthermore, there was good correspondence between predictions and observations in regions that had elevated median observed concentrations for both spatially-explicit models. On the other hand, all three models consistently underestimated median observed concentrations in sediment and soil by 1-3 orders of magnitude. Although regions with elevated median observed concentrations in these environmental media were broadly identified by the spatially-explicit models, the magnitude of the discrepancy between predicted and median observed concentrations is of concern in the context of chemical risk assessment. These results were discussed in terms of factors influencing model performance such as the steady-state assumption, inaccuracies in emission estimates and the representativeness of monitoring data.     

Description and evaluation of a sampling system for monitoring hydrocarbons in sediments

A composite random sampling design was used to estimate the concentrations of hydrocarbons in sediments from two near-shore areas of Scotland (Firth of Clyde and Firth of Forth). The aim of this work was to estimate a mean value for each parameter in these areas, and to determine whether this can be done with more thorough coverage (better representation), better precision and less variance at lower analytical cost through a composite random sampling scheme rather than a simple random sampling scheme, and thereby contribute to the re-design of the UK National Marine Monitoring Programme (NMMP), re-named the UK Clean Seas Environmental Monitoring Programme (CSEMP) in 2006. Samples were collected using a simple random sampling design during 2005. All sediment samples were analysed for their particle size distribution and total organic carbon (TOC). All sediments were analysed for polycyclic aromatic hydrocarbons (PAHs) and n-alkanes. The concentrations of PAHs and n-alkanes in the study areas are described, and sources of PAHs were investigated through the PAH distributions and n-alkane profiles. Individual sediment samples from each area were combined to give a series of composite sub-samples, each comprised of 5 individual sediment samples. These composite samples were re-analysed for the same parameters as the individual samples. Mean total PAH (2- to 6-ring parent and branched) concentrations, based on the individual original sediment samples collected through simple random sampling, were 1858 microg kg(-1) dry weight (SE = 196 microg kg(-1) dry weight, n = 25) and 532.4 microg kg(-1) dry weight (SE = 59 microg kg(-1) dry weight, n = 25) in the Clyde and Forth, respectively. Mean total PAH concentrations of the composite samples were 1745 microg kg(-1) dry weight (SE = 121.0 microg kg(-1) dry weight, n = 5) in the Clyde and 511.6 microg kg(-1) dry weight (SE = 37.4 microg kg(-1) dry weight, n = 5) in the Forth. No significant differences were found between the mean PAH concentrations from the two sampling designs. This study demonstrated that the composite random sampling design gave a mean value with less variance than the simple random sampling design, at significantly reduced analytical effort (and cost).     

A Fast Method for Monitoring Foliage Density in Single Lower-canopy Trees

A subjective visual assessment of foliage density is the mostwidely used rapid method of determining forest health. Forthese assessments to be ecologically meaningful they must bereliable (have low inter- and intra-observer variability) andreadily relate to a measure of physiological or physicalstress. A simple rapid method for assessing percent foliagedensity in lower stature trees is described. This method haslow inter-observer variability (standard deviation betweenobservers=8.6%) and therefore, minimizes the risk ofconfounding the effects of different observers with genuinechanges in density. The percentage changes in this measure offoliage density correlate well with percentage changes inbiomass, allowing a ready interpretation of observed changes.The technique does not specifically identify the cause of themeasured changes, however, with appropriate additionalmeasures this problem may be overcome.     

Assessment of metal contamination using X-ray fluorescence spectrometry and the toxicity characteristic leaching procedure (TCLP) during remediation of a waste disposal site in Antarctica

The remediation of the Thala Valley landfill, Casey Station, East Antarctica, is part of efforts to clean-up contaminated sites associated with the Australian Antarctic Program. These sites, ranging from abandoned rubbish dumps to fuel spills, are contaminated principally with metals and petroleum hydrocarbons. Remediation success depends on accurate, cost-effective and timely--fit-for-purpose--chemical analysis of soil and water samples from the site, which is required to guide excavation, the in situ or off-site treatment and disposal of contaminated material, and to validate satisfactory remediation. Owing to the remote location of Antarctica, it is necessary to carry out chemical analyses on-site. Waste and soil contaminated with Pb, Zn, Cd, and Cu were excavated from Thala Valley for removal to Australia, treatment and disposal. Analysis of total metal concentrations in soil was performed at Casey Station with a transportable energy dispersive X-ray fluorescence (EDXRF) spectrometer. Soil samples were prepared using a simple size-fractionation method to expedite sample throughput. A method for assessing contaminant mobility in solid waste (toxicity characteristic leaching procedure, TCLP) was also used to characterise soil. Although this was more labour-intensive and time-consuming than the total metals analysis, it was of great utility because leachable metals were often significant determinants in the assessment of contaminated soil. The combined data helped managers during remediation, directing excavation and allowing waste to be classified for treatment and disposal before its return to Australia.     

Inter-annual changes in diet and foraging trip lengths in a small pelagic seabird, the thin-billed prion Pachyptila belcheri

Central place foragers are constrained in their foraging distribution by the necessity to return to their nest site at regular intervals. In many petrels that feed on patchily distributed prey from the sea surface over large foraging areas, alternating long and short foraging trips are used to balance the demands of the chick with the requirements of maintaining adult body condition. When the local conditions are favourable for prey density and quality, adults should be able to reduce the number of long foraging trips. We studied the flexibility in foraging trip lengths of a small pelagic petrel, the thin-billed prion Pachyptila belcheri, over three breeding seasons with increasingly favourable, cold-water conditions. During a warm-water influx in February 2006, chicks were fed less frequently and adults carried out foraging trips of up to 8 days. When conditions became more favourable with colder water temperatures in 2007 and 2008, thin-billed prions decreased trip lengths, more often attended their chick every day, and long foraging trips of six to eight days were not registered during 2008. Chick growth rates mirrored this, as chicks grew poorly during 2006, intermediate during 2007 and best during 2008. Thin-billed prions preyed mainly on squid during incubation and mainly on amphipods and euphausiids during chick-rearing. In the poorest season only, the diet was substantially supplemented with very small copepods. Together, the present results indicate that during warm-water conditions, thin-billed prions had difficulties in finding sufficient squid, amphipods or euphausiids and were forced to switch to lower trophic level prey, which they had to search for over large ocean areas.     

Functional traits and the growth-mortality trade-off in tropical trees

A trade-off between growth and mortality rates characterizes tree species in closed canopy forests. This trade-off is maintained by inherent differences among species and spatial variation in light availability caused by canopy-opening disturbances. We evaluated conditions under which the trade-off is expressed and relationships with four key functional traits for 103 tree species from Barro Colorado Island, Panama. The trade-off is strongest for saplings for growth rates of the fastest growing individuals and mortality rates of the slowest growing individuals (r2 = 0.69), intermediate for saplings for average growth rates and overall mortality rates (r2 = 0.46), and much weaker for large trees (r2 < or = 0.10). This parallels likely levels of spatial variation in light availability, which is greatest for fast- vs. slow-growing saplings and least for large trees with foliage in the forest canopy. Inherent attributes of species contributing to the trade-off include abilities to disperse, acquire resources, grow rapidly, and tolerate shade and other stresses. There is growing interest in the possibility that functional traits might provide insight into such ecological differences and a growing consensus that seed mass (SM), leaf mass per area (LMA), wood density (WD), and maximum height (H(max)) are key traits among forest trees. Seed mass, LMA, WD, and H(max) are predicted to be small for light-demanding species with rapid growth and mortality and large for shade-tolerant species with slow growth and mortality. Six of these trait-demographic rate predictions were realized for saplings; however, with the exception of WD, the relationships were weak (r2 < 0.1 for three and r2 < 0.2 for five of the six remaining relationships). The four traits together explained 43-44% of interspecific variation in species positions on the growth-mortality trade-off; however, WD alone accounted for > 80% of the explained variation and, after WD was included, LMA and H(max) made insignificant contributions. Virtually the full range of values of SM, LMA, and H(max) occurred at all positions on the growth-mortality trade-off. Although WD provides a promising start, a successful trait-based ecology of tropical forest trees will require consideration of additional traits.     

A multi‐rater assessment of organizational commitment: are self‐report measures biased?

Most investigations of organizational commitment have been conducted using self‐report measures, however, the veracity of self‐reports is often questioned. In a sample of 79 public‐sector administrative staff, we assessed two types of organizational commitment (affective and continuance) from the perspective of three different sources of raters (self, peer, and supervisor) to test three explanations of the factors influencing self‐report measures (observational opportunities, simple defensiveness, and moderated defensiveness). The pattern of correlations among the measures, analysed using the composite direct product multitrait–multirater approach, suggested that self‐report commitment measures are affected mainly by observations or experiences of the self‐reporter rather than by systematic bias related to defensive responding. This increases our confidence that scores from self‐report measures of affective and continuance commitment are veridical. Further, self‐ and peer‐based measures of commitment were largely redundant in the prediction of a job‐performance criterion whereas supervisory measures added unique predictive variance. Implications are discussed. Copyright © 2001 John Wiley & Sons, Ltd.     

Pre-instrumental perspectives on Arkansas River cross-watershed flow variability

We present four reconstruction estimates of Arkansas River baseflow and streamflow using a total of 78 tree-ring chronologies for three streamflow gages, geographically spanning the headwaters in Colorado to near the confluence of the Arkansas-Mississippi rivers. The estimates represent different seasonal windows, which are dictated by the shared limiting forcing of precipitation on seasonal tree growth and soil moisture—and subsequently on the variability of Arkansas River discharge. Flow extremes that were higher and lower than what has been observed in the instrumental era are recorded in each of the four reconstructions. Years of concurrent, cross-basin (all sites) low flow appear more frequently during the 20th and 21st Centuries compared to any period since 1600 A.D., however, no significant trend in cross-basin low flow is observed. As the most downstream major tributary of the Mississippi River, the Arkansas River directly influences flood risk in the Lower Mississippi River Valley. Estimates of extreme high flow in downstream reconstructions coincide with specific years of historic flooding documented in New Orleans, Louisiana, just upstream of the Mississippi River Delta. By deduction, Mississippi River flooding in years of low Arkansas River flow imply exceptional flooding contributions from the Upper Mississippi River catchments.     

Implications of research on endocrine disruption for the environmental risk assessment, regulation and monitoring of chemicals in the European Union

We assess the implications which research on endocrine disrupting chemicals (EDCs) has for the regulation of synthetic substances and for the protection of the environment, particularly under the forthcoming European Union (EU) REACH legislation. EDCs present regulatory problems inter alia because they can act additively at concentrations which are individually harmless, and they may have non-classical dose (concentration)-response relationships at low exposure levels. Furthermore, current in vivo testing routines were not specifically designed to assess the endocrine disrupting properties of chemicals, whilst in silico and in vitro methods have only limited applicability and availability for this purpose. We need to ensure that the assessment approaches specified in the draft REACH legislation and Technical Guidance are able to evaluate EDCs efficiently. However, it must also be recognised that environmental monitoring procedures in Europe will need to be improved to detect EDCs that have evaded identification, and where appropriate, control, under REACH.     

Reflections: Resolving conflicting demands within disaster risk and recovery

This ‘reflection’ describes conflicting experiences, drawn from the author’s career in varied aspects of disaster risk management and recovery (1973–2016) delving into his memory, Ian Davis explores conflicts he has felt in four parallel roles he has adopted as architect, NGO board member, academic and the personal challenges he has faced working within the humanitarian sector. After describing these encounters, some practical solutions are suggested. The reflection concludes with a suggestion that at the root of these conflicts there is a need for people working in the humanitarian field to become more accountable in a downward direction towards those they seek to serve, who often lack power and influence. These include an architect’s clients, the beneficiaries of an NGO’s concern, an academic’s students or trainees and more broadly an ethical challenge that the author strives after, to regard his work as a vocation, highlighting the need for service to others rather than self-promotion.