Comparison of two methods for obtaining degradation half-lives

Given the paucity of experimental degradation half-life data for most organic chemicals, there is a compelling incentive to use available estimation software when undertaking assessments of chemical persistence and mass balance modeling studies. In this study, half-life data obtained from estimation software for a set of 233 organic chemicals in air, water, soil and sediments were shown to differ significantly from half-life data listed in handbooks. It is suggested that the widely available and used estimation software, EPIWIN (Estimations Program's Interface for Windows), overestimates the reactivity of persistent organic pollutants (POPs). Reasons for this overestimation are explored. It is concluded that the maximum "default half-life values" used by the EPIWIN software are too short for estimating half-lives of highly persistent chemicals such as PCBs. There is a need for estimation software such as EPIWIN to be more thoroughly calibrated against experimental derived half-life data for a wide range of chemicals, including potential POPs, thus improving their reliability.     

Intertemporal and intergenerational Pareto efficiency: A reconsideration of recent extensions

The purpose of this paper is to respond to criticism of the previous representations of Sandler and Smith of the numeraire in an intertemporal analysis of Pareto efficiency conditions. This reexamination suggests that the role of the numeraire is shown to be less clear-cut than Cabe implies. Moreover, the analysis indicates that the earlier conclusions are not crucially dependent on the numeraire assumption.     

How does coaching interviewees affect the validity of a structured interview?

Coaching interviewees to perform in employment interviews can influence the interview scores. We describe different types of coaching, emphasizing interventions designed to focus interviewees on core, interview‐relevant content and to help them convey the content accurately (as opposed to interventions designed to teach interviewees to manipulate their scores using peripheral means). We then study the effects of the former type of intervention in relation to the criterion‐related validity of a structured employment interview. In a combined sample of 146 public safety job incumbents, a predictive validation study was conducted using scores from a situational panel interview. Predictive validity and reliability was observed to be higher in a sample of coached interviewees compared to a sample of uncoached interviewees. Implications for future research and practice in organizational behavior are discussed. Copyright © 2007 John Wiley & Sons, Ltd.     

Identifying hydrologically sensitive areas: bridging the gap between science and application

Researchers have noted that current water quality protection strategies, like nutrient management plans, lack a sound hydrological underpinning for pollutant transport processes. This is especially true for areas like the northeastern U.S. where copious research has shown that variable source area hydrology largely governs runoff generation. The goal of this study was to develop a scientifically justified method to identify the locations that generate overland flow. Furthermore, this methodology must be computationally simple enough that it can be utilized or incorporated into nutrient management plans and other established water quality tools. We specifically tested the reliability of the 'distance from a stream,'D(s), and the 'topographic index,'lambda, to predict areas with a high propensity for generating overland flow, i.e. hydrologically sensitive areas (HSA). HSAs were defined by their probability of generating runoff, P(sat), based on 30 year simulations using a physically based hydrological model. Using GIS, each location's P(sat) was correlated with D(s) and lambda. We used three Delaware Co., NY watersheds in the New York City watershed system with areas varying in size from 1.6 to 37 km2 and with forested and agricultural land uses. The topographic index gave stronger, more regionally consistent correlations with P(sat) than did D(s). Equations correlating lambda and P(sat) for each month are presented and can be used to estimate hydrological sensitivity in the region surrounding our study watersheds, i.e. in Delaware Co. This work is currently being incorporated into an Internet Mapping System to facilitate user-friendly, on-line identification of HSAs.     

Do Energy‐Based PET Models Require More Input Data than Temperature‐Based Models? — An Evaluation at Four Humid FluxNet Sites

It is well established that wet environment potential evapotranspiration (PET) can be reliably estimated using the energy budget at the canopy or land surface. However, in most cases the necessary radiation measurements are not available and, thus, empirical temperature‐based PET models are still widely used, especially in watershed models. Here we question the presumption that empirical PET models require fewer input data than more physically based models. Specifically, we test whether the energy‐budget‐based Priestley‐Taylor (P‐T) model can reliably predict daily PET using primarily air temperature to estimate the radiation fluxes and associated parameters. This method of calculating PET requires only daily minimum and maximum temperature, day of the year, and latitude. We compared PET estimates using directly measured radiation fluxes to PET calculated from temperature‐based radiation estimates at four humid AmeriFlux sites. We found good agreement between P‐T PET calculated from measured radiation fluxes and P‐T PET determined via air temperature. In addition, in three of the four sites, the temperature‐based radiation approximations had a stronger correlation with measured evapotranspiration (ET) during periods of maximal ET than fully empirical Hargreaves, Hamon and Oudin methods. Of the three fully empirical models, the Hargreaves performed the best. Overall, the results suggest that daily PET estimates can be made using a physically based approach even when radiation measurements are unavailable.     

Fish Mercury and Surface Water Sulfate Relationships in the Everglades Protection Area

Few published studies present data on relationships between fish mercury and surface or pore water sulfate concentrations, particularly on an ecosystem-wide basis. Resource managers can use these relationships to identify the sulfate conditions that contain fish with health-concerning total mercury (THg) levels and to evaluate the role of sulfate in methyl-mercury (MeHg) production. In this study, we derived relationships between THg in three fish trophic levels (mosquitofish, sunfish, and age-1 largemouth bass) and surface water sulfate from 1998 to 2009 for multiple stations across the Everglades Protection Area (EPA). Results show the relationship between sulfate and fish THg in each fish type is nonlinear and largely skewed, similar to the relationship between MeHg production and sulfate concentration in peatland sediment pore water identified by other researchers. Peak fish THg levels occurred in ~1 to 12 mg/L sulfate conditions. There was significant variability in the fish THg data, and there were several instances of high-fish THg levels in high-sulfate conditions (>30 mg/L). Health-concerning fish THg levels were present in all surface water sulfate conditions; however, most of these levels occurred in 1–20 mg/L sulfate. The data in this study, including recent studies, show consistent and identifiable areas of high- and low-fish THg across the spectrum of surface water sulfate concentration, therefore, applying an ecosystem-wide sulfur strategy may be an effective management approach as it would significantly reduce MeHg risk in the EPA.     

The acceptability of CO2 capture and storage (CCS) in Europe: An assessment of the key determining factors: Part 1. Scientific,technical and economic dimensions

The ACCSEPT project, which ran from January 2006 to December 2007, identified and analysed the main factors which have been influencing the emergence of CO₂ capture and geological storage (CCS) within the European Union (EU). The key clusters of factors concern science and technology, law and regulation, economics, and social acceptance. These factors have been analysed through interviews, a large-scale questionnaire conducted in 2006, and discussions in two stakeholder workshops (2006 and 2007). In Part I of this paper, we aim to distil the key messages and findings with regards to scientific, technical, legal and economic issues. There are no compelling scientific, technical, legal, or economic reasons why CCS could not be widely deployed in the forthcoming decades as part of a package of climate change mitigation options. In order to facilitate this deployment, governments at both the EU and Member State levels have an important role to play, in particular in establishing a robust and transparent legal framework (e.g. governing long-term environmental liability) and a strong policy framework providing sufficient and long-term incentives for CCS and CO₂ transportation networks.