Nature and extent of metal-contaminated soils in urban environments (keynote talk)

Research on the nature and extent of metal-contaminated soil began with an urban garden study in Baltimore, MD (USA). Largest quantities of soil metals were clustered in the inner city with lesser amounts scattered throughout metropolitan Baltimore. The probability values of metal clustering varied from P value 10^?15–10^?23 depending on element. The inner-city clustering of lead (Pb) could not be explained by Pb-based paint alone. A major Pb source was tetraethyl lead (TEL), developed as an anti-knock agent for use in vehicle fuel, thereby making highway traffic flow a toxic substance delivery system in cities. Further study in Minneapolis and St. Paul confirmed the clustering of inner-city soil metals, especially Pb. Based on the evidence, the Minnesota State Legislature petitioned Congress to curtail Pb additives resulting in the rapid phasedown of TEL on January 1, 1986, 10 years ahead of the EPA scheduled ban. Further research in New Orleans, Louisiana (NOLA), verified the link between soil Pb, blood Pb, morbidity, and societal health. Although Pb is a known cause of clinical impairment, there is no known effective medical intervention for reducing children’s blood Pb exposure. Ingestion and inhalation are routes of exposure requiring prevention, and soil is a reservoir of Pb. Children’s blood Pb exposure observed in pre-Hurricane Katrina (August 29, 2005) NOLA underwent substantial decreases 10 years post-Katrina due to many factors including input of low Pb sediment residues by the storm surge and the introduction of low Pb landscaping materials from outside of the city. Investigation on the topic is ongoing.     

Evaluating tributary restoration potential for Pacific salmon recovery.

Although habitat restoration can play a key role in the conservation of imperiled species, for animals that demonstrate long migrations and complex life histories, reliance on physical restoration of isolated habitat patches comes with considerable uncertainty. Nevertheless, within freshwater ecosystems, stream restoration has become a major conservation focus, with millions of dollars spent annually on efforts aimed at recovering degraded habitat and imperiled riverine species. Within this context, we addressed fundamental uncertainties of the focus on tributary restoration for recovery of salmon: (1) Is there potential for improving habitat in tributaries? (2) What magnitude of early survival improvement can be expected based on stream restoration? and (3) Will incremental increases in early survival be sufficient to ensure viability overall? We combined simple mechanistic habitat models, population viability measures, and categorical filters to quantify "restoration potential," expressed as increased total life-cycle survival in response to restored tributary condition, across 32 populations composing five major population groups (MPG). A wide gap remains between how much survival improvement is needed vs. what is likely to occur; restoration potential meets the necessary minimum increase needed for only four populations within one MPG. The remaining populations (84%, 4 MPG) still fall far below the survival increase needed for future viability. In addition, across all populations and groups, a 171% increase (on average) in total life-cycle survival is needed; only approximately 106% appears possible. A recovery strategy for these salmon that relies largely on tributary restoration to mitigate for known mortality imposed at other life stages (e.g., migration through hydropower dams) is risky with a low probability of success. We demonstrate an approach for completing an a priori evaluation of restoration potential linked to population viability, such that habitat restoration efforts can be biologically prioritized and scarce resources can be allocated to efforts with the greatest potential and the least amount of risk, in terms of meeting conservation and recovery goals.     

Discounting for personal and social payments: Patience for others,impatience for ourselves

The market rate of return on private investment is often used as the discount rate when conducting cost-benefit analysis (CBA) of public projects. I argue that the decision to invest pits current consumption against future consumption, both of which accumulate to the private decision maker. Public projects, on the other hand, provide benefits that accrue to society in general. To examine the appropriateness of discount rates based on returns to private investment, this paper considers lab experiments designed to test whether individuals discount personal and social benefits at different rates. Personal benefits are captured through personal monetary payments, while social benefits are captured through anonymous donations to charitable organizations. I jointly elicit time and risk preferences and find that subjects discount charitable contributions at significantly lower rates than personal payments.     

Soil arsenic surveys of New Orleans: localized hazards in children’s play areas

Arsenic (As) ranks first on the 2005 and 2007 hazardous substances priority lists compiled for the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA). This study describes two New Orleans soil As surveys: (1) a survey of composite soil samples from 286 census tracts and (2) a field survey of soil As at 38 play areas associated with the presence of chromated-copper-arsenate (CCA)-treated wood on residential and public properties. The survey of metropolitan New Orleans soils revealed a median As content of 1.5 mg/kg (range <0.2–16.4) and no distinctive differences between the soils of the city core and outlying areas. Play area accessible soils associated with CCA-treated wood (N = 32) had a median As of 57 mg/kg and 78% of the samples were ≥12 mg/kg, the Louisiana soil As standard. The field survey of play areas for CCA-treated wood (N = 132 samples at 38 sites) was conducted with a portable energy-dispersive X-ray fluorescence (XRF) analyzer. Seventy-five of 132 wood samples (56.8%) were deemed CCA-treated wood. Of the 38 play areas surveyed, 14 (36.8%) had CCA-treated wood. A significant association (Fisher’s exact p-value = 0.348 × 10⁻⁶) was found between CCA-treated wood and soil As (N = 75). At one elementary school CCA-treated woodchips (As range 813–1,654 mg As/kg) covered the playgrounds. The situation in New Orleans probably exists in play areas across the nation. These findings support a precautionary program for testing soils and wood for hazardous substances at all play areas intended for children.     

Assessment of air quality in Turin by personal monitoring of nonsmokers for respirable suspended particles and environmental tobacco smoke

Exposure to respirable suspended particles (RSP), environmental tobacco smoke (ETS) particles, nicotine, and 3-ethenylpyridine (3-EP) was assessed in Turin for 188 subjects during February and March 1995. Personal monitors were worn over a 24-h period, each subject providing a saliva sample for cotinine analysis both prior to and following the monitoring period. Comprehensive lifestyle questionnaires were also completed before and after the 24-h monitoring period. The study comprised housewives in one group, primarily for assessing exposures in the home, and office workers in a second group to assess exposures in the workplace. A single personal monitor was worn by each participating housewife, while employed subjects wore one monitor at work and a separate monitor at home and elsewhere. Based on median 24-h time-weighted average exposures, the most highly exposed subjects to RSP, ETS particles, nicotine, and 3-EP were office workers living with smokers and employed in locations where smoking was allowed. Annualised exposures for nonsmokers living and working in smoking environments indicate that the home contribution to RSP is between 3 and 4 times that obtained from the workplace. Similarly nicotine and ETS particle contributions from the home are, respectively, 4 and 7 times more than those obtained from the workplace. Subjects living and working with smokers had the highest median saliva cotinine levels of 1.7 ng mL⁻¹. Using a cut off level of 25 ng mL⁻¹, up to 6.5% of subjects were found to have misreported themselves as nonsmokers.     

The STRATEGY project: decision tools to aid sustainable restoration and long-term management of contaminated agricultural ecosystems

The STRATEGY project (Sustainable Restoration and Long-Term Management of Contaminated Rural, Urban and Industrial Ecosystems) aimed to provide a holistic decision framework for the selection of optimal restoration strategies for the long-term sustainable management of contaminated areas in Western Europe. A critical evaluation was carried out of countermeasures and waste disposal options, from which compendia of state-of-the-art restoration methods were compiled. A decision support system capable of optimising spatially varying restoration strategies, that considered the level of averted dose, costs (including those of waste disposal) and environmental side effects was developed. Appropriate methods of estimating indirect costs associated with side effects and of communicating with stakeholders were identified. The importance of stakeholder consultation at a local level and of ensuring that any response is site and scenario specific were emphasised. A value matrix approach was suggested as a method of addressing social and ethical issues within the decision-making process, and was designed to be compatible with both the countermeasure compendia and the decision support system. The applicability and usefulness of STRATEGY outputs for food production systems in the medium to long term is assessed.     

Radiocaesium fallout behaviour in volcanic soils in Iceland

The retention of 137Cs in various types of Andosols in Iceland was investigated. Soils were sampled at 29 sites with varying precipitation and environmental conditions. Samples were obtained from 0 to 5, 5 to 10, and 10 to 15 cm depths. The amount of radiocaesium present was quite variable, ranging between 300 and 4800 Bq m(-2) and correlated closely to total annual precipitation (r2=0.71). The majority of 137Cs, 82.7% on average, was retained in the uppermost 5 cm of the soil. The greatest penetration of 137Cs was observed for organic Histosols (76.3% in top 5 cm). The Icelandic Vitrisols (barren, poorly developed Andosols) are coarse grained with only 2-5% clay content and contain little organic matter (<1%). Yet these soils retained 74% of 137Cs in the top 5 cm. The results indicate that radiocaesium fallout is strongly retained by colloidal materials characteristic of Andosols, such as allophane and ferrihydrite. Most soils in Iceland are subject to severe and prolonged freezing and waterlogging; despite this, 137Cs is retained in the upper soil horizons and vertical migration is negligible in Icelandic Andosols. However, erosion and aeolian activity can markedly influence the amount and vertical distribution of radiocaesium in Icelandic soils.     

A compensation mechanism for siting noxious facilities: Theory and experimental design

In locating noxious facilities, such as a trash disposal plant or a hazardous waste disposal incinerator, the host community frequently incurs all the costs while other communities in the region receive the benefits. We propose a mechanism for sharing the benefits with the potential loser. Each community submits a sealed bid indicating the minimum amount it would require to host the facility. The site providing the lowest bid obtains the facility and receives its bid as compensation. This compensation is financed by the other communities. If there are N candidate communities, then each of the other communities would pay 1/(N − 1) of their acceptance bid. A series of controlled laboratory experiments show that the outcomes of this low-bid auction come close to predictions from a theoretical model based on maxi-min rules. Equity and efficiency considerations also are discussed in the context of the noxious facility problem.     

Linking health and ecology in the medical curriculum

Human health vulnerabilities to ecosystem degradation are well documented. Destabilization of natural ecosystems and the biosphere have posed an entirely new set of risks to human health and preclude any simple extrapolations from the past. Newly emerging diseases, increasing prevalence of many vector borne diseases, increased exposure to harmful UV radiation and a number of other transformations in the natural environment, have decidedly negative implications for the sustainability of human health. Curricula in medical schools are responding to these new realities by exposing the connections between health and ecology. The program in Ecosystem Health at the University of Western Ontario serves as one model for connecting these disciplines. This program has resulted in a perceptible shift in values and professional responsibilities of emerging physicians.     

Designing metrics that fit: Rethinking corporate environmental performance measurement systems

If you don't measure it, you can't manage it. Over the past decade, many companies have recognized this need to track environmental performance. Failure to plan metrics systems to fit organizational needs, work flows, and culture has left many companies with costly and ineffective environmental performance measurement systems. This article presents numerous practical steps for designing effective metrics systems which avoid common pitfalls.