Green fairs as venues for civic engagement

We present the first systematic research on green fairs in the USA. We provide a summary analysis of the frequency, trends, goals, structure, and operations of green fairs being held in the USA. We also present an initial assessment of their potential contributions to civic engagement through a study of the intentions and behaviour of fair organisers and fair goers. This assessment is premised on previous research in civic engagement and similar local events with environmental themes, such as farmers' markets. Green fairs are recent, yet now common, events in the USA. Although brief and informal experiences for attendees, green fairs are rich with opportunities to engage people in their community on sustainability and other environmental issues. They are important venues for civic engagement that are distinct from both farmers' markets and from more formal settings for engagement.     

An assessment of lead absorption from soil affected by smelter emissions

The purpose of this study was to assess the oral bioavailability of lead in soil collected from a former smelter site in Sandy, Utah, USA. Sprague-Dawley rats (approximately 4 weeks of age, 5 of each sex in group) were given either soil lead or lead acetate mixed in a purified diet (AIN-93G ) at four different concentrations for 31 consecutive days. Food consumption measurements were used to compute mean daily lead exposures for the soil lead and lead acetate groups. The lead acetate treatment yielded higher concentrations of lead in the blood and bone than the soil lead treatment. Mean blood lead values ranged from below the detection limit (3 g dL^–1) to 27.25 g lead dL^–1 for the lead acetate groups at dose levels of 0.10–2.91 mg lead kg body weight^–1 and from below the detection limit to 8.8 g lead dL^–1 for the soil lead groups at doses of 0.11–3.43 mg lead kg body weight^–1. At these same doses, mean bone values ranged from 0.52 to 26.92 g lead g^–1 for the lead acetate groups and from 0.64 to 13.1 g lead g^–1 for the soil lead groups. Relative per cent bioavailability was estimated by modelling the dose-blood concentration curves for the lead acetate treatment and the dosed soil lead treatment, and then comparing doses that produce an equivalent blood lead concentration. The ratio of the doses of lead acetate and soil lead that produced the same tissue response (i.e., concentration) provided an index of relative bioavailability. For lead, the bioavailability of soil lead relative to lead acetate was 41% at a blood concentration of 6 g lead dL^–1.     

Longevity of granular iron in groundwater treatment processes: changes in solute transport properties over time

Although progress has been made toward understanding the surface chemistry of granular iron and the mechanisms through which it attenuates groundwater contaminants, potential long-term changes in the solute transport properties of granular iron media have until now received relatively little attention. As part of column investigations of alterations in the reactivity of granular iron, studies using tritiated water (3H(2)O) as a conservative and non-partitioning tracer were periodically conducted to independently isolate transport-related effects on performance from those more directly related to surface reactivity. Hydraulic residence time distributions (HRTDs) within each of six 39-cm columns exposed to bicarbonate solutions were obtained over the course of 1100 days of operation. First moment analyses of the data revealed generally modest increases in mean pore water velocity (v) over time, indicative of decreasing water-filled porosity. Gravimetric measurements provided independent estimates of water-filled porosity that were initially consistent with those obtained from 3H(2)O tracer tests, although at later times, porosities derived from gravimetric measurements deviated from the tracer test results owing to mineral precipitation. The combination of gravimetric measurements and 3H(2)O tracer studies furnished estimates of precipitated mineral mass; depending on the assumed identity of the predominant mineral phase(s), the porosity decrease associated with solute precipitation amounted to 6-24% of the initial porosity. The accumulation of mineral and gas phases led to the formation of regions of immobile water and increased spreading of the tracer pulse. Application of a dual-region transport model to the 3H(2)O breakthrough curves revealed that the immobile water-filled region increased from initially negligible values to amounts ranging between 3% and 14% of the total porosity in later periods of operation. For the aged columns, mobile-immobile mass transfer coefficients (k(mt)) were generally in the range of 0.1-1.0 day(-1) and reflected a slow exchange of 3H(2)O between the two regions. Additional model calculations incorporating sorption and reaction suggest that although changes in HRTD can have an appreciable effect on trichloroethylene (TCE) transformation, the effect is likely to be minor relative to that stemming from passivation of the granular iron surface.     

Variability of aquifer sorption properties in a field experiment on groundwater transport of organic solutes: Methods and preliminary results

Methods to characterize the organic solute sorption distribution coefficient, organic carbon content, and specific surface area of aquifer solids from the site of a field experiment on solute transport in groundwater were refined for application to small subsamples of 10-cm depth increments taken from 5-cm diameter cores. Initial results indicate that the average sorption characteristics of the Borden aquifer do not vary appreciably along the trajectory of the solute plumes. However, the sorption distribution coefficient of tetrachloroethylene varied over nearly an order of magnitude among 10-cm depth increments in one core sample. Preliminary evidence suggests that the sorption distribution coefficients for four halogenated organic solutes vary proportionally among core strata. However, the distribution coefficients for sorption of tetrachloroethylene on various depth increments are not well correlated with either organic carbon content or specific surface area, suggesting that as yet unidentified mineral phases may play a significant role in sorption of such solutes by the sandy aquifer solids.     

Effect of a mixture of seven pharmaceuticals on Hyalella azteca over multiple generations

A mixture of seven common pharmaceutical agents (acetaminophen, diclofenac, gemfibrozil, ibuprofen, naproxen, salicylic acid, and triclosan) was tested for its effects on the freshwater amphipod Hyalella azteca over three generations. The target concentration of each chemical (100ngl(-1)) was representative of the upper range observed for these substances in Canadian fresh waters, except in the immediate vicinity of effluent discharges. No statistically significant effects were observed on survival, mating, body size or reproduction. The sex ratio changed slightly to 17% more males. The seven pharmaceuticals tested do not appear to be substances of major concern for Hyalella in most Canadian fresh waters, but significant impacts might be observed in areas closer to effluent discharges.     

The Formation of Reactive Oxygen Species Catalyzed by Neutral,Aqueous Extracts of NIST Ambient Particulate Matter and Diesel Engine Particles

ABSTRACT

It is important to characterize the chemical properties of particulate matter in order to understand how low doses, inhaled by a susceptible population, might cause human health effects. The formation of reactive oxygen species catalyzed by neutral, aqueous extracts of two ambient par-ticulate samples, National Institute of Standards & Technology (NIST) Standard Reference Materials (SRM) 1648 and 1649, and two diesel particulate samples, NIST SRM 1650 and SRM 2975, were measured. The formation of reactive oxygen species was estimated by measuring the formation of malondialdehyde from 2-deoxyribose in the presence of ascorbic acid; H₂O₂ was not added to this assay. SRM 1649, ambient particulate matter collected from Washington, DC, generated the most malondialdehyde, while SRM 2975, diesel particulate matter collected from a forklift, yielded the least amount. Desferrioxamine inhibited the formation of malondialdehyde from the par-ticulate samples providing additional data to support the observation that transition metals were involved in the generation of reactive oxygen species. Six transition metal sulfates (iron sulfate, copper sulfate, vanadyl sulfate, cobalt sulfate, nickel sulfate, and zinc sulfate) were assayed     

A framework of connections between soil and people can help improve sustainability of the food system and soil functions

Globally soil quality and food security continue to decrease indicating that agriculture and the food system need to adapt. Improving connection to the soil by knowledge exchange can help achieve this. We propose a framework of three types of connections that allow the targeting of appropriate messages to different groups of people. Direct connection by, for example, handling soil develops soil awareness for management that can be fostered by farmers joining groups on soil-focused farming such as organic farming or no-till. Indirect connections between soil, food and ecosystem services can inform food choices and environmental awareness in the public and can be promoted by, for example, gardening, education and art. Temporal connection revealed from past usage of soil helps to bring awareness to policy workers of the need for the long-term preservation of soil quality for environmental conservation. The understanding of indirect and temporal connections can be helped by comparing them with the operations of the networks of soil organisms and porosity that sustain soil fertility and soil functions.     

Sorption of 1,2,4-trichlorobenzene and tetrachloroethene within an authigenic soil profile: Changes in Koc with soil depth

The sorption of 1,2,4-trichlorobenzene and tetrachloroethene was investigated in a series of well-controlled batch experiments, using authigenic soil materials from a profile extending to 2.5 m below ground surface. Batch experiment techniques were verified by study with both pulverized and unpulverized soil at different times of equilibration, using two widely different soil:water ratios, and at a wide range of aqueous concentration. Sorption isotherms were approximately linear, with sorption distribution coefficients (K_d) found to decrease roughly 100-fold down the soil profile. K_d decreased with depth to an extent greater than could be predicted on the basis of the only 10-fold decrease in natural solid organic matter (SOM) content and despite significantly higher specific surface area in the lower horizons. All base-extractable SOM in these deeper soil horizons was operationally defined as fulvic acid (FA), although there was also a significant fraction that was not extracted by the standard base technique. The lower K_d of the deeper soil horizons is believed to reflect a complex combination of (1) lower SOM content; (2) a more hydrophilic form of SOM; and (3) a more intimate association of the SOM with the mineral fraction, affecting its accessibility, sorptivity, or both. For the deeper horizons, an increase in overall K_d by more than 4-fold was observed on solids treated by either base extraction or H₂O₂ treatment, demonstrating that sorption to remaining soil components could be dramatically increased by fractional SOM removal and/or chemical alteration of the soil. A simple regression model that divides SOM into only two types (shallow and deep SOM) provides a reasonably good explanation of sorption in all seven horizons and suggests an order-of-magnitude variability in K_oc among surface soil and deeper horizons.