Validation studies of an automated preconcentration water sampler (APS) for chlorinated dibenzo-p-dioxins and dibenzofurans

An Automated Preconcentration Sampler (APS) was developed by the Ontario Ministry of the Environment (MOE) and Carleton University for the determination of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) in drinking water. The APS employs a two-stage particulate filtration system followed by an XAD-2 resin column. Field and laboratory testing of the APS is required to validate the device before it is put into regular service.The capacity of the APS filtration system is 30 L for a 4 Formazin Turbidity Unit (FTU) input water turbidity and greater than 50 L for a typical treated water. Flushing of a clean XAD-2 resin column with 200 L of spiked water showed that the optimum flowrate in terms of spike breakthrough is equal to three times the resin bed volume per minute. This flowrate is used for APS operation. Testing also showed that no spike breakthrough occurred after 200 L of clean water was flushed through a spiked XAD-2 resin column at flowrates in excess of the APS operating flowrate. Spike testing was also carried out on the filters and results are pending. An analytical comparison between the present MOE sampling and analytical procedure and the proposed APS sampling and analytical procedure using a PCDD/PCDF source water is planned.     

Open-path tunable diode laser absorption spectroscopy for acquisition of fugitive emission flux data

Air pollutant emission from unconfined sources is an increasingly important environmental issue. The U.S. Environmental Protection Agency (EPA) has developed a ground-based optical remote-sensing method that enables direct measurement of fugitive emission flux from large area sources. Open-path Fourier transform infrared spectroscopy (OP-FTIR) has been the primary technique for acquisition of pollutant concentration data used in this emission measurement method. For a number of environmentally important compounds, such as ammonia and methane, open-path tunable diode laser absorption spectroscopy (OP-TDLAS) is shown to be a viable alternative to Fourier transform spectroscopy for pollutant concentration measurements. Near-IR diode laser spectroscopy systems offer significant operational and cost advantages over Fourier transform instruments enabling more efficient implementation of the measurement strategy. This article reviews the EPA's fugitive emission measurement method and describes its multipath tunable diode laser instrument. Validation testing of the system is discussed. OP-TDLAS versus OP-FTIR correlation testing results for ammonia (R2 = 0.980) and methane (R2 = 0.991) are reported. Two example applications of tunable diode laser-based fugitive emission measurements are presented.     

Phthalates and the aquatic environment: Part I The effect of di-2-ethylhexyl phthalate (DEHP) and di-isodecyl phthalate (DIDP) on the reproduction of Daphnia magna and observations on their bioconcentration

$\text{Daphnia magna}$ were exposed to di-2-ethylhexyl phthalate (DEHP) and to di-isodecyl phthalate (DIDP) at nominal concentrations up to 100 μg/1 over a 21 day period. The phthalates had no effect on reproduction, and the parent $\text{Daphnia}$ showed bioconcentration factors of 209 (DEHP) and 116 (DIDP) as determined by ¹⁴C analysis.     

Thermodynamic considerations in dibenzodioxin and dibenzofuran formation: Concentrations of chlorinated dioxins and furans in model fuel-rich combustion gases

A database for chlorinated dioxins (DBDs), with heats of formation derived by analogy with chlorination of quinone and benzene, has already been shown to predict relative isomer distributions nearer to those observed, and those predicted using MOPAC, than an earlier database due to Shaub. The model has been extended to obtain a similar database for chlorinated dibenzofurans (DBF's), and comparisons with observed isomer concentration distributions are illustrated. Calculations are carried out using the NPL MTDATA suite of programs. Isomer group values for the properties of the original compounds and each degree of chlorination have been derived, and the use of these values leads to a reduction in the data obtained in computations to more manageable proportions. The reduced database obtained is combined with other databases to carry out computer predictions for simulated chlorine-containing combustion gases. Data for inorganics substances and the simplest organic substances (methane. ethane and related species) are obtained from the SGTE database. More extensive data for aliphatic and aromatic hydrocarbons from various standard sources have been incorporated in an additional computational database. In order to examine the relative concentrations of DBFs and DBDs a database for chlorinated hydrocarbons has been established. Predictions for simulated fuel rich combustion products for the C, H, O, Cl system are presented.     

Exposure efficiency: concept and application to perchloroethylene exposure from dry cleaners

Standard approaches for computing population exposures due to specific sources of air pollutants are relatively complex. In many cases, more simple and approximate methods would be useful. This paper develops an approach, based on the concept of exposure efficiency, that may be used for estimating the impact of a source (or source class) on the integrated population exposure. The approach is illustrated by an example, which uses the concept of exposure efficiency to examine the impact of perchloroethylene emissions from dry cleaners in the United States. The paper explores the geographic variability of exposure efficiency by evaluating it for each of 100 randomly selected dry cleaners. For perchloroethylene, which has a long atmospheric residence time, the site-to-site variability in exposure efficiency is found to be relatively small. This suggests that simple exposure assessments, based on generic distributional characterizations of exposure efficiency, may be used in risk assessments without introducing appreciable uncertainty. For many compounds, like perchloroethylene, the uncertainty inherent in the estimation of cancer potency or source emissions would dominate these small errors.     

The reproductive cycle and physiological ecology of the mussel Mytilus edulis in a subarctic,non-estuarine environment

Mytilus edulis L. occupies a habitat in eastern Newfoundland, Canada, which is characterised by low temperatures and a lower concentration of particles in suspension than is found in estuarine locations. Gametogenesis occurs in the spring, and energy reserves from the previous year are not utilised in the synthesis of gametes. Oxygen uptake is not elevated during the winter, in contrast to most European populations, which undergo gamete development at that time. There is little seasonal variation in clearance rate. This may be attributable in part to the absence of the high particulate load which has been shown to depress feeding activity in some estuarine populations. Energy balance is positive at all times of the year, and conversion efficiency is high, suggesting that conditions are favourable. A number of physiological comparisons are made between Newfoundland mussels and those from European waters.     

Isolation of heavy metal binding proteins from marine vertebrates

Cadmium binding proteins have been isolated from liver homogenates of marine vertebrates by ultracentri fugation and gel filtration. Liver samples of the Atlantic grey seal Halichoerus grypus and the Pacific fur seal Callorhinus ursinus contain measurable quantities of cadmium binding protein. The copper rock fish Sebastodes caurinus showed an increase in hepatic cadmium binding protein on administration of CdCl₂, in agreement with the known inducible nature of the protein isolated from terrestrial animals. The apparent molecular weights of the isolated proteins were 9000 for the grey seal, 10,000 for the fur seal, and 11,000 for the copper rock fish, as determined by gel filtration.     

Population biology of hyperbenthic crustaceans in a cold water environment (Conception Bay,Newfoundland). II.<Emphasis Type="Italic"> Acanthostepheia malmgreni</Emphasis> (Amphipoda)

Seasonal population dynamics of the gammarid Acanthostepheia malmgreni Goës in Conception Bay, Newfoundland, were examined from October 1998 to November 2000. This species exhibited a 2.5-year life span, with the reproductive cycle correlating with seasonal phytoplankton flux. Females were semelparous and died following a 5-month brooding period and the subsequent release of juveniles in April and May. The biennial life cycle of this population should result in the presence of two cohorts in the hyperbenthos at any given time. However, the cohorts alternated in strength from year to year, which affected annual density, biomass and production during the study period. Densities were 64±87 ind. per 100 m³ in 1999 and 491±492 ind. per 100 m³ (mean±SD) in 2000. Secondary production was estimated at 18–44 mg C m^–2 in 1999 and 180–311 mg C m^–2 in 2000. The annual P/B ratios were 0.89 and 2.27 in 1999 and 2000, respectively. Growth varied both among and within cohorts, with different life-history stages exhibiting variable growth rates ranging from 0 to 12 mg dry mass month^–1.Communicated by J.P. Grassle, New Brunswick     

Songbird abundance and parasitism differ between urban and rural shrublands.

Many studies have examined differences in avian community composition between urban and rural habitats, but few, if any, have looked at nesting success of urban shrubland birds in a replicated fashion while controlling for habitat. We tested factors affecting nest survival, parasitism by the Brown-headed Cowbird (Molothrus ater), and species abundance in shrubland habitat in rural and urban landscapes. We found no support for our hypothesis that nest survival was lower in urban landscapes, but strong support for the hypothesis that survival increased with nest height. We found strong support for our hypothesis that cowbird parasitism was greater in urban than rural landscapes; parasitism in urban sites was at least twice that of rural sites. We found strong support for an urban landscape effect on abundance for several species; Northern Cardinal (Cardinalis cardinalis) and Brown-headed Cowbirds were more abundant in urban landscapes, whereas Field Sparrow (Spizella pusilla) and Blue-winged Warbler (Vermivora pinus) were more abundant in rural sites. There was support for lower abundances of Blue-gray Gnatcatcher (Polioptila caerulea) and Indigo Bunting (Passerina cyanea) with increased housing density. For six other species, edge and trail density or vegetation parameters best explained abundance. Lower abundances and greater parasitism in habitat patches in urban landscapes are evidence that, for some species, these urban landscapes do not fulfill the same role as comparable habitats in rural landscapes. Regional bird conservation planning and local habitat management in urban landscapes may need to consider these effects in efforts to sustain bird populations at regional and local scales.