bluuebunny/crossref_metadata_2025_split huggingface dataset:
Runoff simulation with particle-associated azinphosmethyl in multispecies stream microcosms: Implications for the field
Authors: Thiere Geraldine , Schulz Ralf 
Published: November 2004

Abstract
We investigated the acute (5 d) effects of particle-associated azinphosmethyl (AZP) in multispecies microcosms and assessed the results in the context to data obtained from a parallel field study undertaken in the Lourens River, South Africa. A runoff simulation was carried out in stream microcosms containing the macroinvertebrate fauna of an uncontaminated Lourens River site exposed to particle-associated AZP (control and 200, 1,000, 5,000, 20,000 μg/kg; three replicates each) for 1 h. Measured AZP concentrations in filtered microcosm water resulted in the following values: Not detectable (control) and 0.03, 0.2, 1.1, and 6.9 μg/L, respectively. The two highest treatments resulted in significantly (analysis of variance [ANOVA]) reduced total numbers of individuals, while the number of taxa was affected in the 20,000 μg/kg treatment only. A comparison with previous data suggests that observed effects partly resulted from particle-associated AZP. Particularly affected were six out of 14 macroinvertebrate taxa such as mayfly and stonefly taxa. In parallel, the distribution of macroinvertebrates at a pesticide-free and a contaminated stretch of the Lourens River was monitored five times during the spraying season in 2001 and 2002. Out of the 14 core taxa found in the microcosm study as well as in the field approach, 10 showed comparable reactions in the microcosm experiment and in their field distribution; they were either classified as affected or unaffected in both studies. Thus, we conclude that particle-associated AZP has the potential to affect the invertebrate community structure of the Lourens River and that microcosm studies employing fieldrelevant exposure scenarios may be valuable for a local risk assessment of pesticide-related community disruptions in the Lourens River.
Obtaining quantitative vapor emissions estimates of polychlorinated biphenyls and other semivolatile organic compounds from contaminated sites
Authors: Mills William J. , Bennett Erin R. , Schmidt Charles E. , Thibodeaux Louis J. 
Published: November 2004

Abstract
Soils contaminated with polychlorinated biphenyls (PCBs) and other semivolatile organic compounds (SVOs) represent a potentially major, ongoing source of these compounds to the environment, especially during warmer temperatures. A great deal of work has been devoted to understanding the mechanisms that govern the vaporization of SVOCs from soil, but to date, few quantitative estimates have been published regarding emissions from contaminated sites. The present paper describes methods for obtaining quantitative estimates of SVOCs from soils based on flux chamber measurements, modeling, and ambient air measurements. On wet (i.e., H2O) soils, SVOCs at very low chemical loading levels on the adsorption sites (the so-called critical chemical concentration, critical loading, or saturation concentration) will behave, for volatilization purposes, as the pure-liquid substance would. For one soil, the PCB critical concentration was determined to be 775 ppm (95% confidence interval, 5.40E+02). Flux chamber-measured emissions from two contaminated sites were used and compared to model estimated values. The results agree reasonably well and indicate that the modeling approach used provided a conservative upper bound on the emissions. These approaches can be used to develop emissions estimates for SVOC-contaminated sites and inputs to air dispersion models.
Multimedia persistence as an indicator of potential for population-level intake of environmental contaminants
Authors: MacLeod Matthew , McKone Thomas E. 
Published: November 2004

Abstract
Although intuitively it is apparent that population-level exposure to contaminants dispersed in the environment must be related to the persistence of the contaminant, there has been little effort to quantify this link formally. In this paper we investigate the relationship between overall persistence and/or overall residence time in a multimedia exposure environment and the population-level intake of contaminants as expressed by intake fraction (iF), the cumulative fraction of chemical emitted to the environment that is taken up by members of the population. We demonstrate that for any given contaminant and emission scenario the definition of iF implies that it is directly proportional to the overall multimedia persistence (POV), or the overall multimedia residence time (TOV). The proportionality constant has dimensions of time and represents the characteristic time for population intake (CTI) of the chemical from the environment. We then apply the CalTOX fate and exposure model to explore how TOV and CTI combine to determine the magnitude of iF. We find that CTI has a narrow range of possible values relative to TOV across multiple chemicals and emissions scenarios. We use data from the Canadian Environmental Protection Act Priority Substance List (PSL1) Assessments and multimedia POV to show that exposure assessments based on empirical observation are consistent with interpretations from the model. Results indicate that POV derived from screening-level assessments of persistence, bioaccumulation potential, and toxicity (PBT) is a useful indicator of the potential for population-level exposure.
Investigating the mechanics of multimedia box models: How to explain differences between models in terms of mass fluxes?
Authors: Scheringer Martin , Wegmann Fabio , Hungerbühler Konrad 
Published: November 2004

Abstract
The simple mathematical structure of multimedia fate models makes it possible to change the process descriptions and geometry of such models relatively easily. With different versions of a model, the effect of a process or compartment that is included in one version of the model but excluded in another version can be investigated. Here, a new method for performing such a model comparison in a quantitative way is presented. Based on the mass balances for the two model versions, it can be shown that, for a compartment contained in both model versions, the difference between a chemical's concentrations in this compartment is related directly to the difference in those mass fluxes that have different rate constants in the two models. Moreover, it is possible to identify the contributions to the concentration difference that stem from individual mass fluxes so that the concentration difference can be tracked back to specific differences in the process descriptions of the two models. This flux analysis method is illustrated with two versions of a unit-world model, one with and one without a vegetation compartment. With DDT and six polychlorinated biphenyl (PCB) congeners as example chemicals, the differences of the chemicals' concentrations in air and soil caused by the vegetation compartment are explained by using the flux analysis method. The future potential of the method for comparing not only versions of the same model but also models of different structure is discussed.
Dependency of polychlorinated biphenyl and polycyclic aromatic hydrocarbon bioaccumulation in Mya arenaria on both water column and sediment bed chemical activities
Authors: Lohmann Rainer , Burgess Robert M. , Cantwell Mark G. , Ryba Steven A. , MacFarlane John K. , Gschwend Philip M. 
Published: November 2004

Abstract
The bioaccumulation of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) by the filter-feeding soft-shell clam Mya arenaria was evaluated at three sites near Boston (MA, USA) by assessing the chemical activities of those hydrophobic organic compounds (HOCs) in the sediment bed, water column, and organisms. Polyethylene samplers were deployed to measure the activities of HOCs in the water column. Sediment activities were assessed by normalizing concentrations with sediment-water sorption coefficient values, including adsorption to black carbon in addition to absorption by organic carbon. Likewise, both lipids and proteins were considered in biota-water partition coefficients used to estimate chemical activities in the animals. Chemical activities of PAHs in M. arenaria were substantially less than those of the corresponding bed sediments in which they lived. In contrast, chemical activities of PCBs in M. arenaria often were greater than or equal to activities in the corresponding bed sediments. Activities of PAHs, such those of pyrene, in the water column were undersaturated relative to the sediment. However, some PCBs, such as congener 52, had higher activities in the water column than in the sediment. Tissue activities of pyrene generally were in between the sediment and water column activities, whereas activity of PCB congener 52 was nearest to water column activities. These results suggest that attempts to estimate bioaccumulation by benthic organisms should include interactions with both the bed sediment and the water column.
Sediments are major sinks of steroidal estrogens in two United Kingdom rivers
Authors: Peck Mika , Gibson Richard W. , Kortenkamp Andreas , Hill Elizabeth M. 
Published: November 2004

Abstract
The occurrence of intersex fish in a number of European rivers has been attributed to exposure to estrogenic chemicals present in sewage treatment work (STW) effluents. To further understand the environmental fate of these contaminants, the estrogenic activity of effluents, water, and sediments were investigated both upstream and downstream of the major STW discharge in two United Kingdom rivers. Estrogenic activity, determined using the yeast estrogen-receptor transcription screen, of the major STW effluents on both rivers was similar, ranging from 1.4 to 2.9 ng 17β-estradiol equivalents (EEQ)/L. Estrogenic activities of surface waters 1 km upstream and downstream of both STW inputs were less than the limits of detection (0.04 ng/L); however, levels of estrogenic activity in sediments were between 21.3 and 29.9 ng EEQ/kg and were similar at both upstream and downstream sites. Effluent and sediment extracts were fractionated by reverse phase-high-performance liquid chromatography, and estrogenic active fractions were further analyzed by gas chromatography-mass spectrometry. The major active chemicals in the two effluents and in the sediments were estrone with lesser amounts of 17β-estradiol; however, at one site, a number of other unidentified estrogenic fractions were detected in the sediments. These results suggest that riverine sediments are a major sink and a potential source of persistent estrogenic contaminants.
Effects of chronic dietary copper exposure on growth and reproduction of Daphnia magna
Authors: De Schamphelaere Karel A. C. , Janssen Colin R. 
Published: November 2004

Abstract
A matter of current, intense debate with regard to the effects of metals on biological systems is the potential toxicity of metals associated with food particles. Recently developed biotic ligand models (BLM), which predict the toxicity of waterborne metals, may not be valid if the dietary exposure route contributes to metal toxicity. The present study is, to our knowledge, the first that investigates the potential toxicity of dietary copper to a freshwater invertebrate (i.e., Daphnia magna) feeding on a live diet (i.e., the green alga Pseudokircheneriella subcapitata). Algae were exposed for 3 d to different copper concentrations, resulting in algal copper burdens between approximately 6.2 × 10−16 and 250 × 10−16 g cell−1. These algae were then used as food in chronic, 21-d D. magna toxicity tests in which growth, reproduction, and copper accumulation were assessed. Three exposure scenarios were tested: A waterborne exposure, a dietary exposure, and a combined waterborne and dietary exposure. Although exposure to dietary copper resulted in an increased copper body burden of the adult daphnids, it did not contribute to toxicity and did not affect the 21-d effect concentrations expressed as waterborne copper, indicating that the previously established good predictive capacity of the chronic D. magna BLM is not affected. On the contrary, exposure to the highest dietary copper levels resulted in an increase of as much as 75% in growth and reproduction. To our knowledge, this is the first evidence that dietary copper exposure of a freshwater invertebrate feeding on a live diet resulted in a beneficial effect.
Toxicity of oil sands to early life stages of fathead minnows (Pimephales promelas)
Authors: Colavecchia Maria V. , Backus Sean M. , Hodson Peter V. , Parrott Joanne L. 
Published: November 2004

Abstract
The present study examines the effects of exposure to oil sands on the early life stages (ELS) off fathead minnows (Pimephales promelas). Sediments within and outside natural oil sand deposits were collected from sites along the Athabasca River (AB, Canada). The ELS toxicity tests were conducted with control water, natural oil sands, reference sediments, and oil-refining wastewater pond sediments. Eggs and larvae were exposed to 0.05 to 25.0 g sediment/L and observed for mortality, hatching, malformations, growth, and cytochrome P4501A induction as measured by immunohistochemistry. Natural bitumen and wastewater pond sediments caused significant hatching alterations and exposure-related increases in ELS mortality, malformations, and reduced size. Larval deformities included edemas, hemorrhages, and spinal malformations. Exposure to reference sediments and controls showed negligible embryo mortality and malformations and excellent larval survival. Sediment analyses using gas chromatography–mass spectrometry revealed high concentrations of alkyl-substituted polyaromatic hydrocarbons (PAHs) compared to unsubstituted PAHs in natural oil sands (220–360 μg/g) and oil-mining wastewater pond sediments (1,300 μg/g). The ELS sediment toxicity tests are rapid and sensitive bioassays that are useful in the assessment of petroleum toxicity to aquatic organisms.
Fate and metabolism of [15N]2,4,6-trinitrotoluene in soil
Authors: Weiß Martin , Geyer Roland , Russow Rolf , Richnow Hans H. , Kästner Matthias 
Published: November 2004

Abstract
The fates of the labels from [14C] and [15N] trinitrotoluene were analyzed in bioreactors under aerobic conditions in soil treated by a fungal bioremediation process with Stropharia rugosoannulata and in control soil. Up to 17.5% of the 15N label had a different fate than the 14C label. Three N-mineralization processes were identified in detailed experiments with [15N]TNT. About 2% of the 15N label was found as NO3− and NH4−, showing simultaneous processes of direct TNT denitration (I) and reduction with cleavage of the amino groups (II). The enrichment of NO2−/NO3− (up to 7.5 atom% 15N abundance) indicates the formation of Meisenheimer complexes with a denitration of [15N]TNT. A 1.4% of the label was found distributed between N2O and N2. However, the 15N enrichment of the N2O (up to 38 atom%) demonstrated that both N atoms were generated from the labeled TNT and clearly indicates a novel formation process (III). We propose, as an explanation, the generation of N2O by cleavage from condensed azoxy metabolites. In addition, 1.7% of the 15N label was detected as biogenic amino acids in the wheat straw containing the fungus. Overall, 60 to 85% of the applied [15N]TNT was degraded and 52 to 64% was found as nonextractable residues in the soil matrix. Three percent was detected as 2-amino-4,6-dinitrotoluene and 4-amino-2,6-dinitrotoluene.
Passive air sampling of polycyclic aromatic hydrocarbons and polychlorinated naphthalenes across europe
Authors: Jaward Foday M. , Farrar Nick J. , Harner Tom , Sweetman Andrew J. , Jones Kevin C. 
Published: November 2004

Abstract
This study presents concurrently sampled ambient air data for a range of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated naphthalenes (PCNs) at the continental scale. This was achieved with a passive air sampling system, by deploying polyurethane foam disks, which were prepared in one laboratory, sealed to prevent contamination, sent out by courier to volunteers participating in different countries, exposed for six weeks, collected, resealed, and returned to the laboratory for analysis. The study area was Europe, a region with a history of extensive persistent organic pollutants usage and emission, and with marked national differences in population density, the degree of urbanization and industrial and agricultural development. Samplers were deployed at remote, rural, and urban locations in 22 countries. Calculated air concentrations were broadly in line with those obtained by conventional active air sampling techniques, for both compound classes and for compounds existing predominantly in the gas and particle phases. The geographical compound distribution reflected suspected regional emission patterns and highlighted localized source areas. Both PAH and PCN levels varied by more than two orders of magnitude. The implications for sources are discussed.
Aquatic persistence of eight pharmaceuticals in a microcosm study
Authors: Lam Monica W. , Young Cora J. , Brain Richard A. , Johnson David J. , Hanson Mark A. , Wilson Christian J. , Richards Sean M. , Solomon Keith R. , Mabury Scott A. 
Published: November 2004

Abstract
The persistence of eight pharmaceuticals from multiple classes was studied in aquatic outdoor field microcosms. A method was developed for the determination of a mixture of acetaminophen, atorvastatin, caffeine, carbarnazepine, levofloxacin, sertraline, sulfamethoxazole, and trimethoprim at μg/L levels from surface water of the microcosms using solid phase extraction and high-performance liquid chromatography-ultraviolet (HPLC-UV) and liquid chromatography tandem mass spectrometry (LC-MS-MS). Half-lives in the field ranged from 1.5 to 82 d. Laboratory persistence tests were performed to determine the relative importance of possible loss processes in the microcosms over the course of the study. Results from dark control experiments suggest hydrolysis was not important in the loss of the compounds. No significant differences were observed between measured half-lives of the pharmaceuticals in sunlight-exposed pond water and autoclaved pond water, which suggests photodegradation was important in limiting their persistence, and biodegradation was not an important loss process in surface water over the duration of the study. Observed photoproducts of several of the pharmaceuticals remained photoreactive, which led to further degradation in irradiated surface waters.
Interactive effects of p,p′-dichlorodiphenyldichloroethylene and methoxychlor on hormone synthesis in largemouth bass ovarian cultures
Authors: Borgert Christopher J. , Gross Timothy S. , Guiney Patrick D. , Osimitz Tomas G. , Price Bertram , Wells Christopher 
Published: November 2004

Abstract
p,p′-Dichlorodiphenyldichloroethylene (DDE) and methoxychlor were tested alone and in combination to assess the similarity of their actions on hormone synthesis in gonadal tissue from largemouth bass (Micropterus salmoides floridanus), a species whose reproductive fitness has relevance to ecosystem health in Florida (USA). Gonads were harvested from adult female bass (age, two to three years) during the peak reproductive season (January–May), minced, and incubated in culture medium with or without test agents for 48 h. Duplicates of each treatment were performed in each of three experiments using tissue from a different female. Both 17β-estradiol and testosterone were measured in aliquots of culture medium by validated radioimmunoassay procedures. Dose–response relationships of individual agents were characterized over a 6-log concentration range (1 × 10−2 to 1 × 104 ppb). Both DDE and methoxychlor, tested individually, produced a dose-dependent decrease in testosterone levels. 17β-Estradiol levels were unaffected. Mixtures of the agents were tested at all concentration combinations of 0.01, 1, 100, and 10,000 ppb in culture medium. Statistical tests indicated that of 16 dose combinations tested, 15 were antagonistic, and only 1 was additive based on the Loewe additivity model of no interaction. These results imply that methoxychlor and DDE inhibit testosterone production by different mechanisms in bass ovaries.
Quantitative measurement of fathead minnow vitellogenin by liquid chromatography combined with tandem mass spectrometry using a signature peptide of vitellogenin
Authors: Zhang Fagen , Bartels Michael J. , Brodeur Julie C. , Woodburn Kent B. 
Published: November 2004

Abstract
Vitellogenin (VTG) has been proposed as a sensitive biomarker of exposure to environmental estrogenic contaminants that induce VTG production in oviparous species. Enzyme-linked immunosorbent assay (ELISA) methods are currently widely used to measure the VTG levels. In this paper, a new liquid chromatography combined with tandem mass spectrometry (LC/ESI-MS/MS) method for the quantitative analysis of VTG in the plasma of fathead minnows exposed to 17α-ethinylestradiol (EE2) has been developed. This method includes, first, the selection of the signature peptide, which involves sodium dodecyl sulfate-poly-arylamide gel electrophoresis separation, in-gel digestion, LC/ESI-MS/MS analysis with an ion trap mass spectrometer, and sequence determination with the TurboSEQUEST MS/MS database application; second, optimization of the selected signature peptide in multireaction monitor (MRM) mode with a triple quadrupole mass spectrometer; and third, trypsin digestion of plasma and VTG quantitation via MRM-mode LC/ESI-MS/MS. A series of plasma samples from fathead minnows following exposure to EE2 was assayed. A good correlation was found when EE2-induced plasma samples from fathead minnows were analyzed with ELISA and the described new method. Although used here with fathead minnow, the new LC/ESI-MS/MS method could be easily applied to the analysis of VTG expressed in any other fish species. Quantitation of VTG by this method was found to be highly specific and linear. The absence of potential artifactual measurements of VTG at low exposure levels could also be critical in future studies that evaluate weakly estrogenic compounds in aquatic species.
Putting science into persistence, bioaccumulation, and toxicity evaluations
Authors: Webster Eva , Cowan-Ellsberry Christina E. , McCarty Lynn 
Published: November 2004

Abstract
In recent decades, advances have been made in the processes used to identify substances as persistent, bioaccumulative, and toxic (PBT). Key processes have been identified, and scientifically sound assessment methods have been developed. Regulatory agencies around the world have sought practical methods for implementing policies to protect both environment and human health. In the present paper, we review the various contributions that Mackay (in collaboration with his students and colleagues) has made to the development of scientifically sound methods for the identification of PBT substances and persistent organic pollutants. These contributions include efforts to clearly define the terminology and to develop scientifically defensible assessment models and evaluation frameworks.