Source, concentration, and distribution of elemental mercury in the atmosphere in Toronto, Canada

Atmospheric gaseous elemental mercury [GEM] at 1.8, 4, and 59 m above ground, in parking lots, and in indoor and outdoor air was measured in Toronto City, Canada from May 2008-July 2009. The average GEM value at 1.8 m was 1.89 ± 0.62 ng m(-3). The GEM values increased with elevation. The average GEM in underground parking lots ranged from 1.37 to 7.86 ng m(-3) and was higher than those observed from the surface parking lots. The GEM in the indoor air ranged from 1.21 to 28.50 ng m(-3), was higher in the laboratories than in the offices, and was much higher than that in the outdoor air. All these indicate that buildings serve as sources of mercury to the urban atmosphere. More studies are needed to estimate the contribution of urban areas to the atmospheric mercury budget and the impact of indoor air on outdoor air quality and human health.     

Applying sustainable development principles to contaminated land management using the SuRF‐UK framework

In the past decade, management of historically contaminated land has largely been based on prevention of unacceptable risks to human health and the environment, to ensure a site is “fit for use.” More recently, interest has been shown in including sustainability as a decision‐making criterion. Sustainability concerns include the environmental, social, and economic consequences of risk management activities themselves, and also the opportunities for wider benefit beyond achievement of risk‐reduction goals alone. In the United Kingdom, this interest has led to the formation of a multistakeholder initiative, the UK Sustainable Remediation Forum (SuRF‐UK). This article presents a framework for assessing “sustainable remediation”; describes how it links with the relevant regulatory guidance; reviews the factors considered in sustainability; and looks at the appraisal tools that have been applied to evaluate the wider benefits and impacts of land remediation. The article also describes how the framework relates to recent international developments, including emerging European Union legislation and policy. A large part of this debate has taken place in the “grey” literature, which we review. It is proposed that a practical approach to integrating sustainability within risk‐based contaminated land management offers the possibility of a substantial step forward for the remediation industry, and a new opportunity for international consensus. © 2011 Wiley Periodicals, Inc.     

Assessing exposure to allied ground troops in the Vietnam War: A quantitative evaluation of the Stellman Exposure Opportunity Index model

The Exposure Opportunity Index (EOI) is a proximity-based model developed to estimate relative exposure of ground troops in Vietnam to aerially applied herbicides. We conducted a detailed quantitative evaluation of the EOI model by using actual herbicide spray missions isolated in time and space. EOI scores were calculated for each of 36 hypothetical receptor location points associated with each spray mission for 30 herbicide missions for two time periods – day of herbicide application and day 2–3 post-application. Our analysis found an enormous range of EOI predictions with 500–1000-fold differences across missions directly under the flight path. This quantitative examination of the EOI suggests that extensive testing of the model’s code is warranted. Researchers undertaking development of a proximity-based exposure model for epidemiologic studies of either Vietnam veterans or the Vietnamese population should conduct a thorough and realistic analysis of how precise and accurate the model results are likely to be and then assess whether the model results provide a useful basis for their planned epidemiologic studies.     

A monitoring study of workers handling pesticides in warehouses and godowns

Abstract

Monitoring observations made on 60 operators involved in pesticide application work in godowns and warehouses and 60 matched control workers are reported. Occupational exposure history and medical history are noted. Biochemical investigations, plasma and RBC cholinesterase estimations are included along with medical examination of the workers. Workers were found to be mostly exposed to Celphos, DDVP, Malathion, Pyrethrum, etc, and the use of protective devices were very limited. Cases of significant reduction in plasma and RBC cholinesterase activity were found. Frequency of symptoms like dizziness, headache, lachrymation, burning sensation in eyes, nausea and anorexia, etc, were much more in the exposed workers. No cases of clinical poisoning attributable to occupational exposure to pesticides were reported by the workers.     

Flue Gas NOX Reduction Using Ammonia Radical Injection

A novel technique has been developed for flue gas NO_X reduction through the injection of plasma-treated ammonia and its decomposition products. Numerical investigation of the chemical kinetics shows nearly complete NO removal when ammonia radicals are injected into the flue gas. The feasibility of this new technique was experimentally explored on a small-scale laboratory combustor at Carnegie Mellon University and concurrently on a larger-scale combustor at the DOE Pittsburgh Energy Technology Center. Preliminary experimental results have shown that ammonia plasma-injection is more effective than simple ammonia-injection at low flue gas temperatures. NO_X reduction of 85 to 90 percent was achieved at a low plasma power input. This technique is expected to provide additional opportunities for inexpensive and effective NO_X reduction in stationary sources.     

Limitations of Long-Path Averaging Instruments

ABSTRACT

Long-path averaging instruments measure the average velocity or concentration of a substance or substances over an averaging path. These measurements are then often used for calculation of the average concentration and mass flow rate of the substance. The purpose of this paper is to describe some of the limitations of these instruments and to suggest ways in which these limitations can be minimized. Two limitations were examined: measuring concentration in a single dimension (e.g., ignoring the variation in concentration over the width of the sample plane), and deriving an average concentration without considering velocity effects. The resultant errors will be application-specific.

Estimates of the second source of error can be obtained from the covariance of concentration and velocity profiles over the path length. Unfortunately, suitable field data were not available, and to illustrate the method, estimates of the error were obtained for a range of possible concentration and velocity profiles. Errors of 50% or greater in the mass flow were incurred for the concentration and velocity profiles considered. This error was reduced to a negligible level by segmenting the averaging path length. It is recommended that velocity and concentration profiles be obtained for a broad range of applications to enable the importance of covariance errors to be better assessed.     

Improving petroleum contaminated land remediation decision-making through the MCA weighting process

Internationally petroleum contamination is widespread, posing serious environmental risks including surface and groundwater contamination, thus remediation is essential. The implementation of remediation options is becoming more complex with the increasing influence of stakeholders on the outcome of decision-making processes. Acceptance of remediation schemes during implementation can be increased by involving stakeholders and the public in the decision-making stage. In petroleum remediation involving multiple stakeholders, Multicriteria Analysis has been employed due to its ability to incorporate the preferences of each stakeholder through weighting. The research focused on investigating ways to improve the weighting process. The study demonstrated the utility of SWING, and determined which type of participant and how many participants to include in the decision process, through the application of ELECTRE III and Weighted Summation. It was recommended that a mixture of stakeholders, the public and experts be involved. The total number of participants will be limited by the choice of participatory and weighting methods. The careful selection of participants, as well as the choice of participatory and weighting methods, can minimize the subjectivity involved in MCA weighting, thereby lending decisions in petroleum remediation greater legitimacy.     

Fecundity and spawning in a deep-water cirromorph octopus

 Reproductive characteristics of cirromorph octopuses, assigned to the species Opisthoteuthis grimaldii, were sampled as a commercial fishing by-catch on the Hebrides Slope, west of Scotland. A total of 254 specimens (99 female, 155 males), retrieved from bottom trawls fished at 750 to 1500 m depth, were examined. A maximum of 2097 eggs was counted in a single female ovary (mean female body weight 1242.8 g), most of them <1 mm in length. At egg lengths over 1 mm, diminishing numbers of eggs were present in 1 mm size categories up to a maximum of ≈10 mm. At body sizes >500 g (wet wt), and in every female >750 g (max. female weight recorded in the sample was 2959 g), a succession of unattached eggs was present in the proximal oviduct and a single, unattached mature egg occupied the tip of the distal oviduct. These females were assumed to be in spawning condition and the characteristics of egg distribution in the reproductive tract to be consistent with sequential release of individual eggs and continuous spawning throughout the growth period and lifespan of the mature octopus. In pre-spawning females there was a positive relationship between estimated egg numbers and maximum egg size. After the onset of spawning there was no significant further increase in estimated potential fecundity over the body-size range 500 to 3000 g. Follicular sheaths remaining in the ovary after release of eggs into the proximal oviduct were counted and used to estimate the total number of eggs released up to the time of capture. Follicular sheaths first appeared at 500 to 650 g body weight and increased steeply in number to >1000 in females >1500 g. Two individuals were found with ovarian follicular sheaths but with no terminal egg in the distal oviduct; these were assumed to have released their egg just before capture. Summation of the number of follicular sheaths counted plus the number of eggs estimated as remaining attached in the ovisac, provided a revised estimate of total potential fecundity and raised the estimate for any individual to a maximum of 3202 eggs (mean = 1396 eggs). Received: 3 February 2000 / Accepted: 17 May 2000     

Does cannibalism in Spodoptera frugiperda (Lepidoptera: Noctuidae) reduce the risk of predation?

The incidence of cannibalism of larval Spodoptera frugiperda (Lepidoptera: Noctuidae) on maize under field conditions was investigated using field cages. Cannibalism was found to account for approximately 40% mortality when maize plants were infested with two or four fourth-instar larvae over a 3-day period. Field trials examined the effect of larval density on the prevalence of natural enemies of S. frugiperda. The abundance of predators (earwigs, staphylinids, other predatory beetles, and Chrysoperla spp.) was significantly greater on maize plants with higher levels of larval feeding damage, while the relationship between predator abundance and number of S. frugiperda larvae per plant was less clear. As larval damage is probably a more reliable indicator of previous larval density than numbers collected at an evaluation, this indicates that predation risk will be greater for larvae living in large groups. Parasitism accounted for 7.1% mortality of larvae in sorghum, and involved six species of Hymenoptera and Tachinidae. There was no effect of larval density or within-plant distribution on the probability of larval attack by parasitoids. The selective benefits of cannibalism, in relation to the risk of predation and parasitism, are discussed. Received: 23 March 2000 / Accepted: 24 June 2000     

Geomechanical analysis of the Naylor Field,Otway Basin,Australia: Implications for CO2 injection and storage

A geomechanical assessment of the Naylor Field, Otway Basin, Australia has been undertaken to investigate the possible geomechanical effects of CO₂ injection and storage. The study aims to evaluate the geomechanical behaviour of the caprock/reservoir system and to estimate the risk of fault reactivation. The stress regime in the onshore Victorian Otway Basin is inferred to be strike–slip if the maximum horizontal stress is calculated using frictional limits and DITF (drilling induced tensile fracture) occurrence, or normal if maximum horizontal stress is based on analysis of dipole sonic log data. The NW–SE maximum horizontal stress orientation (142°N) determined from a resistivity image log is broadly consistent with previous estimates and confirms a NW–SE maximum horizontal stress orientation for the Otway Basin.An analytical geomechanical solution is used to describe stress changes in the subsurface of the Naylor Field. The computed reservoir stress path for the Naylor Field is then incorporated into fault reactivation analysis to estimate the minimum pore pressure increase required to cause fault reactivation (ΔP_p).The highest reactivation propensity (for critically-oriented faults) ranges from an estimated pore pressure increase (ΔP_p) of 1 MPa to 15.7 MPa (estimated pore pressure of 18.5–33.2 MPa) depending on assumptions made about maximum horizontal stress magnitude, fault strength, reservoir stress path and Biot's coefficient. The critical pore pressure changes for known faults at Naylor Field range from an estimated pore pressure increase (ΔP_p) of 2 MPa to 17 MPa (estimated pore pressure of 19.5–34.5 MPa).