bluuebunny/crossref_metadata_2025_split huggingface dataset:
A food web bioaccumulation model for organic chemicals in aquatic ecosystems
Authors: Arnot Jon A. , Gobas Frank A. P. C. 
Published: November 2004

Abstract
The present study examines a new bioaccumulation model for hydrophobic organic chemicals in aquatic food webs. The purpose of the model is to provide site-specific estimates of chemical concentrations and associated bioconcentration factors, bioaccumulation factors, and biota-sediment accumulation factors in organisms of aquatic food webs using a limited number of chemical, organism, and site-specific data inputs. The model is a modification of a previous model and incorporates new insights regarding the mechanism of bioaccumulation derived from laboratory experiments and field studies as well as improvements in model parameterization. The new elements of the model include: A model for the partitioning of chemicals into organisms; kinetic models for predicting chemical concentrations in algae, phytoplankton, and zooplankton; new allometric relationships for predicting gill ventilation rates in a wide range of aquatic species; and a mechanistic model for predicting gastrointestinal magnification of organic chemicals in a range of species. Model performance is evaluated using empirical data from three different freshwater ecosystems involving 1,019 observations for 35 species and 64 chemicals. The effects of each modification on the model's performance are illustrated. The new model is able to provide better estimates of bioaccumulation factors in comparison to the previous food web bioaccumulation model while the model input requirements remain largely unchanged.
Environmental quality criteria for organic chemicals predicted from internal effect concentrations and a food web model
Authors: Traas Theo P. , van Wezel Annemarie P. , Hermens Joop L. M. , Zorn Mathilde , van Hattum Albertus G. M. , van Leeuwen Cornelis J. 
Published: November 2004

Abstract
Environmental quality criteria (EQC) for hydrophobic organic chemicals were calculated with a model for bioaccumulation in food webs. The model was calibrated and verified using polychlorinated biphenyl concentrations in food webs of shallow lakes. The EQCs in water and sediment were derived based on internal effect concentrations (IECs) for several modes of toxic action. By reverse calculation with the food web model for each organism in the web, a different water or sediment concentration is calculated corresponding to the IEC in each organism. A statistical procedure with an acute-to-chronic value is used to derive chronic EQCs based on bioaccumulation. The model-based chronic EQCs were compared with previously established EQCs. The EQCs calculated with the food web model generally are within an order of magnitude of the previously derived EQCs based on toxicity data on individual chemicals. Some previously derived EQCs are much lower than model predictions and usually based on small samples of toxicity data such as no-observed-effect concentrations (NOECs) with large assessment factors. When faced with data gaps, it is proposed to use model-based chronic EQCs for (polar) narcotic chemicals. Other modes of action require a different model concept to account for receptor-based toxicity.
Association of heavy metals with metallothionein and other proteins in hepatic cytosol of marine mammals and seabirds
Authors: Ikemoto Tokutaka , Kunito Takashi , Anan Yasumi , Tanaka Hiroyuki , Baba Norihisa , Miyazaki Nobuyuki , Tanabe Shinsuke 
Published: November 2004

Abstract
Distribution of Cu, Zn, Cd, Ag, Hg, and Se were determined in hepatocytosol of northern fur seals (Callorhinus ursinus), black-footed albatrosses (Diomedea nigripes), and Dall's porpoises (Phocoenoides dalli). Copper, Zn, and Cd were accumulated preferentially in metallothionein (MT) fraction and their contents in MT fraction increased with the amounts in the hepatocytosol. Silver was bound to both high-molecular-weight substances (HMWS) and MT in the hepatocytosol for all three species, whereas the distribution of Ag in the cytosol was different among the three species. In northern fur seals, Ag mainly was bound to MT, whereas it mainly was associated with HMWS in Dall's porpoises. In contrast, Ag was distributed almost equally in both HMWS and MT for black-footed albatrosses. Mercury content in HMWS and Se content in HMWS and low-molecular-weight substances (LMWS) increased with their contents in hepatocytosol for all the three species. A significant positive correlation was found between Se and Hg contents in high-molecular weight (HMW) fraction in cytosol. The molar ratio of Hg and Se was close to unity in HMW fraction of the specimens with high Hg concentration in cytosol, implying that the Hg–Se complex was bound to the HMWS. Analysis of metals in the hepatocytosol by high-performance liquid chromatography/inductively coupled plasma–mass spectrometry (HPLC/ICP-MS) suggests that multiple isoforms of MT are present in hepatocytosol of the three species and that the metal profiles in hepatocytosols are different among the species. To our knowledge, this is the first report on the association of Ag with HMWS and MT in hepatocytosol of marine mammals and seabirds. Also, distribution and interaction of Hg and Se were investigated for the first time in hepatocytosol of the higher trophic marine animals.
Osmotic distress: A probable cause of fish kills on exposure to a subbloom concentration of the toxic alga Chattonella marina
Authors: Tang Janet Y. M. , Au Doris W. T. 
Published: November 2004

Abstract
Mortality, changes in blood osmolality, and pO2 in the goldlined seabream (Rhabdosargus sarba) on exposure to a subbloom concentration (2,000 cells/ml) of a toxic red tide alga, Chattonella marina, were investigated and related to quantitative ultrastructural alterations of the gill. The median lethal time (LT50) was 6 h. Significant induction of filamental chloride cells (CCs) (increases in CC density, apical opening area, fractional area, volume densities of CCs, and mitochondria within CCs), concomitant with a significant reduction in blood osmolality, was found within 3 h of exposure to C. marina. Further reduction in blood osmolality (67%) and a drastic decline of pO2 (70%) were detected in moribund fish after 6 h. Fish were also subjected to severe salinity stress (abrupt transfer to 0 and 60‰ salinities), and the same parameters were measured. Our quantitative ultrastructural and physiological data suggest that fish exposed for 6 h to C. marina (2,000 cells/ml) suffered similar but more severe osmotic distress as compared to that induced by abrupt transfer to 60‰ persaline water. Results of the salinity stress experiment also showed that suffocation was not a secondary response induced by osmotic impairment in the moribund fish. Osmoregulatory failure in conjunction with suffocation may be the cause of death following exposure to C. marina. The findings of this study provide evidence that C. marina, even in concentrations below visible blooms, can pose a significant threat to marine fish.
Incorporating monte carlo analysis into multimedia environmental fate models
Authors: Citra Mario J. 
Published: November 2004

Abstract
We have incorporated a Monte Carlo module into a steady state nonequilibrium level III fugacity model in order to account for variability in degradation half-lives and observe the effects that this variability has on the model outputs. This method leads to a distribution of important output parameters such as the overall persistence time, which can be used in decision-making processes or risk assessment. For herbicides such as atrazine, where the emission rate primarily is to the soil compartment, it is shown that the main contribution to the variability in overall persistence time is the soil degradation half-life.
Maternal transfer of selenium in Alligator mississippiensis nesting downstream from a coal-burning power plant
Authors: Roe John H. , Hopkins William A. , Baionno Jennifer A. , Staub Brandon P. , Rowe Christopher L. , Jackson Brian P. 
Published: November 2004

Abstract
Selenium (Se) is embryotoxic in many oviparous vertebrates, but little is known about maternal transfer of Se and its impact in reptiles. Over a four-year period, we collected three clutches of eggs of the American alligator (Alligator mississippiensis) from a single nest at a site contaminated with Se and compared egg and hatchling Se concentrations and clutch viability from this nest to nests downstream from the contaminated site (two clutches from two nests) and at a reference site (two clutches from two nests). Eggs and hatchlings from the nest at the Se-contaminated site and downstream nests had elevated Se concentrations (2.1–7.8 ppm) and lower viability (30–54%) compared to reference nests (1.4–2.3 ppm and 67–74% viability), but Se concentrations did not exceed reproductive toxicity thresholds established for other oviparous vertebrates. Selenium concentrations were higher in chorioallantoic membranes of eggs from Se-contaminated sites, suggesting that this tissue may be useful as a nondestructive index of Se exposure for embryos of A. mississippiensis. Examination of these data suggests that further studies on uptake, accumulation, and reproductive success of crocodilian embryos exposed to excessive Se are warranted.
The enhanced biodegradation of fenamiphos in soils from previously treated sites and the effect of soil fumigants
Authors: Karpouzas Dimitrios Georgios , Hatziapostolou Polydoros , Papadopoulou-Mourkidou Euphemia , Giannakou Ioannis O. , Georgiadou Athena 
Published: November 2004

Abstract
The application of fenamiphos either alone or in combination with soil fumigants is a common practice in greenhouses and potato-cultivation areas in Greece. However, repeated applications of fenamiphos in the same field for a number of years can lead to the development of enhanced biodegradation of the nematicide. Studies in previously treated greenhouse sites and potato field sites in Greece were employed in order to investigate the development of enhanced biodegradation of fenamiphos and the respective effect of soil fumigants on the development of the phenomenon. Enhanced biodegradation of fenamiphos in a soil from a previously treated greenhouse site from the area of Aggelohori in Northern Greece was observed using both incubation and bioassay studies with nematodes. Fumigation of the enhanced soil with methyl bromide (MeBr) only temporarily inhibited degradation of fenamiphos unlike metham sodium (MS) whose application significantly reduced microbial degradation of fenamiphos. Similarly, enhanced biodegradation of fenamiphos was evident in soil from potato fields that had a history of previous exposure to fenamiphos. The slow rates of fenamiphos degradation observed in soils from the previously treated sites after sterilization with broad-spectrum antibiotics and also in soils from previously untreated sites suggested that soil microorganisms were responsible for its rapid degradation. The inhibition of enhanced biodegradation of fenamiphos in soil from the previously treated greenhouse site caused by the antibiotic penicillin probably indicates that Gram+ or other bacteria sensitive to penicillin are responsible for the rapid degradation of fenamiphos in this soil. No cross-adaptation was observed between fenamiphos and other nematicides registered in Greece for the control of root-knot and potato cyst nematodes, including cadusafos, ethoprophos, and oxamyl. According to our results, applications of MS followed by fenamiphos or in rotation with other registered nematicides are the most promising means for minimizing the risk of development of enhanced biodegradation of fenamiphos in soils.
Finding and estimating chemical property data for environmental assessment
Authors: Boethling Robert S. , Howard Philip H. , Meylan William M. 
Published: November 2004

Abstract
The ability to predict the behavior of a chemical substance in a biological or environmental system largely depends on knowledge of the physicochemical properties and reactivity of that substance. We focus here on properties, with the objective of providing practical guidance for finding measured values and using estimation methods when necessary. Because currently available computer software often makes it more convenient to estimate than to retrieve measured values, we try to discourage irrational exuberance for these tools by including comprehensive lists of Internet and hard-copy data resources. Guidance for assessors is presented in the form of a process to obtain data that includes establishment of chemical identity, identification of data sources, assessment of accuracy and reliability, substructure searching for analogs when experimental data are unavailable, and estimation from chemical structure. Regarding property estimation, we cover estimation from close structural analogs in addition to broadly applicable methods requiring only the chemical structure. For the latter, we list and briefly discuss the most widely used methods. Concluding thoughts are offered concerning appropriate directions for future work on estimation methods, again with an emphasis on practical applications.
Chemical speciation and cellular deposition of lead in Sesbania drummondii
Authors: Sharma Nilesh C. , Gardea-Torresdey Jorge L. , Parsons Jason , Sahi Shivendra V. 
Published: November 2004

Abstract
The internalized speciation of lead in roots and leaves of Sesbania drummondii, a lead hyperaccumulator, grown in lead nitrate solution was studied using x-ray absorption near-edge structure and extended x-ray absorption fine structure. Lead was predominantly present as lead acetate in both plant tissues. The other dominant forms of accumulation were lead–sulfur compounds. Whereas lead sulfate and sulfide were found in leaves, only lead sulfide was detected in root samples. These observations indicate that S. drummondii is able to biotransform lead nitrate in the nutrient solution to lead acetate and sulfate in its tissues. Complexation with acetate and sulfate may be a lead detoxification strategy in this plant. Transmission-electron microscopy revealed the pattern of lead distribution in and around the cells. Dense distributions of lead grains were detected in root cell walls and plasma membranes, whereas evidence for vacuolar transport of lead was noticed in the stem cells.
Development of toxicity identification evaluation procedures for pyrethroid detection using esterase activity
Authors: Wheelock Craig E. , Miller Jeff L. , Miller Mike J. , Gee Shirley J. , Shan Guomin , Hammock Bruce D. 
Published: November 2004

Abstract
Recent agrochemical usage patterns suggest that the use of organophosphate (OP) pesticides will decrease, resulting in a concomitant increase in pyrethroid usage. Pyrethroids are known for their potential toxicity to aquatic invertebrates and many fish species. Current toxicity identification evaluation (TIE) techniques are able to detect OPs, but have not been optimized for pyrethroids. Organophosphate identification methods depend upon the use of piperonyl butoxide (PBO) to identify OP-induced toxicity. However, the use of PBO in TIE assays will be confounded by the co-occurrence of OPs and pyrethroids in receiving waters. It is necessary, therefore, to develop new TIE procedures for pyrethroids. This study evaluated the use of a pyrethroid-specific antibody, PBO, and carboxylesterase activity to identify pyrethroid toxicity in aquatic toxicity testing with Ceriodaphnia dubia. The antibody caused significant mortality to the C. dubia. Piperonyl butoxide synergized pyrethroid-associated toxicity, but this effect may be difficult to interpret in the presence of OPs and pyrethroids. Carboxylesterase activity removed pyrethroid-associated toxicity in a dose-dependent manner and did not compromise OP toxicity, suggesting that carboxylesterase treatment will not interfere with TIE OP detection methods. These results indicate that the addition of carboxylesterase to TIE procedures can be used to detect pyrethroids in aquatic samples.
Intestinal absorption and biomagnification of organic contaminants in fish, wildlife, and humans
Authors: Kelly Barry C. , Gobas Frank A. P. C. , McLachlan Michael S. 
Published: November 2004

Abstract
Methods for the regulatory assessment of the bioaccumulation potential of organic chemicals are founded on empirical measurements and mechanistic models of dietary absorption and biomagnification. This study includes a review of the current state of knowledge regarding mechanisms and models of intestinal absorption and biomagnification of organic chemicals in organisms of aquatic and terrestrial food chains and also includes a discussion of the implications of these models for assessing the bioaccumulation potential of organic chemicals. Four mechanistic models, including biomass conversion, digestion or gastrointestinal magnification, micelle-mediated diffusion, and fat-flush diffusion, are evaluated. The models contain many similarities and represent an evolution in understanding of chemical bioaccumulation processes. An important difference between the biomagnification models is whether intestinal absorption of an ingested contaminant occurs solely via passive molecular diffusion through serial resistances or via facilitated diffusion that incorporates an additional advective transport mechanism in parallel (i.e., molecular ferrying within gastrointestinal micelles). This difference has an effect on the selection of physicochemical properties that best anticipate the bioaccumulative potential of commercial chemicals in aquatic and terrestrial food chains. Current regulatory initiatives utilizing Kow threshold criteria to assess chemical bioaccumulation potential are shown to be unable to identify certain bioaccumulative substances in air-breathing animals. We urge further research on dietary absorption and biomagnification of organic chemicals to develop better models for assessing the bioaccumulative nature of organic chemicals.
Shortcomings of the laboratory-derived median lethal concentration for predicting mortality in field populations: Exposure duration and latent mortality
Authors: Zhao Yuan , Newman Michael C. 
Published: November 2004

Abstract
Exposure duration and intensity (concentration or dose) determine lethal effects of toxicants. However, environmental regulators have focused on exposure intensity and have considered duration only peripherally. Conventional testing for toxicology tends to fix exposure time and to use the median lethal concentration (LC50) at that time to quantify mortality. Fixing the exposure duration and selecting the 50% mortality level for reasons of statistical and logistical convenience result in the loss of ecologically relevant information generated at all other times and ignore latent mortality that manifests after the exposure ends. In the present study, we used survival analysis, which is widely employed in other fields, to include both time and concentration as covariates and to quantify latent mortality. This was done with two contrasting toxicants, copper sulfate (CuSO4) and sodium pentachlorophenol (NaPCP). Amphipods (Hyalella azteca) were exposed to different toxicant concentrations, and the percentage mortalities were noted both during and after the exposure ended. For CuSO4 at the conventional 48-h LC50 concentrations, the predicted proportions dead after including latent mortality were 65 to 85%, not 50%. In contrast, only 5% or fewer additional animals died if the latent mortality was included for NaPCP. The data (including exposure time, concentration, and proportion dead at each time) for each toxicant were then successfully fit with survival models. The proportion of organisms dying at any combination of exposure concentration and time can be predicted from such models. Survival models including latent mortality produced predictions of lethal effects that were more meaningful in an ecological or field context than those from conventional LC50 methods.
Location-specific ecotoxicological risk assessment of metal-polluted soils
Authors: van Beelen Patrick , Wouterse Marja , Posthuma Leo , Rutgers Michiel 
Published: November 2004

Abstract
When chemical analysis indicates metal pollution, a second-tier method is needed to evaluate whether toxic effects occur at the polluted sites. A method based on pollution-induced community tolerance (PICT) was developed using samples taken from locations polluted with sewage more than 20 years ago. Microorganisms extracted from soil samples were exposed to a concentration range of zinc, nickel, copper, chromium (III), or chromium (VI) salts in a buffer suspension. The remaining activity of the intoxicated microorganisms was determined by color formation with 31 different organic substrates in microtiter plates. Microorganisms from moderately Zn-polluted sites (&gt;45 mg/kg) showed an increased tolerance for zinc. Nickel tolerance was observed at 51 mg Ni/kg soil, chromium (VI) tolerance at 923 mg Cr/kg. In most cases, tolerance also was observed at higher concentrations. High concentrations of 1,494 mg Cu/kg or 3,935 mg Cr/kg did not show PICT, indicating a limited bioavailability of Cu and Cr at these sites. The benefits of our method are its greater sensitivity compared to other tests used at these sites, and its specificity for those metals that exceed allowable levels.
Development of a passive, in situ, integrative sampler for hydrophilic organic contaminants in aquatic environments
Authors: Alvarez David A. , Petty Jimmie D. , Huckins James N. , Jones-Lepp Tammy L. , Getting Dominic T. , Goddard Jon P. , Manahan Stanley E. 
Published: November 2004

Abstract
Increasingly it is being realized that a holistic hazard assessment of complex environmental contaminant mixtures requires data on the concentrations of hydrophilic organic contaminants including new generation pesticides, pharmaceuticals, personal care products, and many chemicals associated with household, industrial, and agricultural wastes. To address this issue, we developed a passive in situ sampling device (the polar organic chemical integrative sampler [POCIS]) that integratively concentrates trace levels of complex mixtures of hydrophilic environmental contaminants, enables the determination of their time-weighted average water concentrations, and provides a method of estimating the potential exposure of aquatic organisms to the complex mixture of waterborne contaminants. Using a prototype sampler, linear uptake of selected herbicides and pharmaceuticals with log KowS &lt; 4.0 was observed for up to 56 d. Estimation of the ambient water concentrations of chemicals of interest is achieved by using appropriate uptake models and determination of POCIS sampling rates for appropriate exposure conditions. Use of POCIS in field validation studies targeting the herbicide diuron in the United Kingdom resulted in the detection of the chemical at estimated concentrations of 190 to 600 ng/L. These values are in agreement with reported levels found in traditional grab samples taken concurrently.