bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of urea on degradation of terbuthylazine in soil
Authors: Caracciolo Anna Barra , Giuliano Giuseppe , Grenni Paola , Cremisini Carlo , Ciccoli Roberto , Ubaldi Carla 
Published: April 2005

Abstract
Pesticide and nitrate contamination of soil and groundwater from agriculture is an environmental and public health concern worldwide. The herbicide terbuthylazine (CBET) has replaced atrazine in Italy and in many other countries because the use of the latter has been banned because of its adverse environmental impacts. Unlike atrazine, knowledge about the fate of CBET in soil is still not extensive, especially regarding its transformation products, but recent monitoring data show its occurrence and that of its main metabolite, desethyl-terbuthylazine (CBAT), in groundwater above the limit of 0.1μg/L established by European Union Directive and Italian legislation. The objective of this work was to investigate if the presence of the fertilizer urea affects CBET degradation in the soil. Laboratory CBET degradation experiments in the presence/absence of urea were performed with microbiologically active soil and sterilized soil. Terbuthylazine degradation rates under the different experimental conditions were assessed, and the formation, degradation, and transformation of the metabolite CBAT were also studied. Terbuthylazine degradation was affected by the presence of urea, in terms both of a higher disappearance time of 50% of the initial concentration and of a lower amount of CBAT formed. These findings have practical implications for the real-life assessment of the environmental fate of triazine herbicides in agricultural areas since these herbicides are frequently applied to soils receiving ureic fertilizers.
Joint effects of density and a growth inhibitor on the life history and population growth rate of the midge Chironomus riparius
Authors: Hooper Helen L. , Sibly Richard M. , Hutchinson Thomas H. , Maund Stephen J. 
Published: April 2005

Abstract
Results of previous laboratory studies suggest that high population density often buffers the effects of chemical stressors that predominately increase mortality. Mortality stressors act to release more resources for the survivors and, therefore, produce less-than-additive effects. By contrast, growth stressors are expected to have opposite results or more-than-additive effects. We investigated the effects of a growth inhibitor (lufenuron) on larval growth and survival of Chironomus riparius and examined its joint effects with density on population growth rate (PGR). Exposure to 60 μg/kg sediment or greater inhibited larval growth, and exposure to 88 μg/kg or greater often resulted in mortality before reaching emergence. The effects of lufenuron, however, differed with population density. At 88 μg/kg, mortalities and, to a lesser extent, reduced fecundity resulted in a reduction in PGR at low density. Conversely, when populations were initiated at high density, PGR was similar to that of controls, because the few survivors reached maturity sooner and started producing offspring earlier. The effect of density as a growth stressor therefore was stronger than the effect of lufenuron, which had effects similar to those of a mortality stressor and produced less-than-additive effects. Long-term studies under field conditions, however, are needed before less-than-additive effects are considered to be the norm.
Acute contamination with esfenvalerate and food limitation: Chronic effects on the mayfly, Cloeon dipterum
Authors: Beketov Mikhail A. , Liess Matthias 
Published: April 2005

Abstract
Results of environmental risk assessments based merely on toxic effects of contaminants at the individual level, without consideration of population-level effects, may be questionable. The aim of the present study was to investigate how limited food resources, resulting in intraspecific competition, could interact with the chronic effect of short-term contamination with the insecticide esfenvalerate. Larvae of the mayfly, Cloeon dipterum, were exposed to esfenvalerate (0.001–100 μg/L) for 1 h and then transferred to indoor microcosms containing insecticide-free water, where they were maintained at various food levels until emergence. The results showed that short-term exposure to 10 or 100 μg/L resulted in acute mortality. Chronic effects on survival occurred at concentrations up to three orders of magnitude lower than that causing the acute effect (0.01 μg/L). Food limitation increased effects on organisms during medium-term observation (8–15 d), but assessment of long-term survival rates suggested that the chronic effects of low insecticide concentrations could be compensated for, at least regarding some endpoints. The authors assume that in limited-food conditions, lethal and sublethal effects reduced competition between individuals, resulting in significantly increased final survival.
Acute and chronic toxicity of mercury to early life stages of the rainbow mussel, Villosa iris (Bivalvia: Unionidae)
Authors: Valenti Theodore W. , Cherry Donald S. , Neves Richard J. , Schmerfeld John 
Published: April 2005

Abstract
Mercury (Hg) contamination is receiving increased attention globally because of human health and environmental concerns. Few laboratory studies have examined the toxicity of Hg on early life stages of freshwater mussels, despite evidence that glochidia and juvenile life stages are more sensitive to contaminants than adults. Three bioassays (72-h acute glochidia, 96-h acute juvenile, and 21-d chronic juvenile toxicity tests) were conducted by exposing Villosa iris to mercuric chloride salt (HgCl2). Glochidia were more sensitive to acute exposure than were juvenile mussels, as 24-, 48-, and 72-h median lethal concentration values (LC50) for glochidia were &gt;107, 39, and 14 μg Hg/L, respectively. The 24-, 48-, 72-, and 96-h values for juveniles were 162, 135, 114, and 99 μg Hg/L, respectively. In the chronic test, juveniles exposed to Hg treatments ≥8 μg/L grew significantly less than did control organisms. The substantial difference in juvenile test endpoints emphasizes the importance of assessing chronic exposure and sublethal effects. Overall, our study supports the use of glochidia as a surrogate life stage for juveniles in acute toxicity tests. However, as glochidia may be used only in short-term tests, it is imperative that an integrated approach be taken when assessing risk to freshwater mussels, as their unique life history is atypical of standard test organisms. Therefore, we strongly advocate the use of both glochidia and juvenile life stages for risk assessment.
RNA/DNA ratios as a sublethal endpoint for large-scale toxicity tests with the nematode Caenorhabditis elegans
Authors: Ibiam Udu , Grant Alastair 
Published: April 2005

Abstract
Caenorhabditis elegans increasingly is attractive as a toxicity test organism, particularly as a model system to study mechanisms of toxicity at a molecular level and the way that these lead to whole organism and population level effects. Inhibitions of growth, reproduction, movement, and feeding rate all have been proposed as sublethal toxicity endpoints. These endpoints are more sensitive than 24-h acute toxicity endpoints, but assays are much more time consuming, making them difficult to use in mass screening. The RNA/DNA ratio, after 48-h exposure to metals, has median effective concentration (EC50) values of 0.05, 0.6, 6.1, and 35 mg/L for Cu, Pb, Cd, and Zn, respectively. This makes it a slightly more sensitive toxicity endpoint than reduction of individual growth after 72-h exposure to the same concentrations. This facilitates the near-simultaneous assessment of sublethal toxicity in many nematode samples. The constant cell number of C. elegans means that different stages in the life history have very different RNA/DNA ratios even in the absence of toxins. So, RNA/DNA ratios can be used only on prereproductive, age-synchronized cultures. Assessing the sublethal toxicity of metals to C. elegans shows that it is sensitive particularly to Cu.
Sorption of benzidine and 3,3′-dichlorobenzidine to lake sediments. 1. conceptualization and development of a multiparameter model
Authors: Donaldson Francis P. , Nyman Marianne C. 
Published: April 2005

Abstract
Aromatic amines, such as benzidine and 3,3′-dichlorobenzidine (DCB), are part of the dyes and pigments manufacturing process. The prolonged use of these carcinogenic chemicals in the past generation has introduced a significant amount of contamination to the environment. Their persistency in several mediums has sparked a number of studies in an attempt to develop predictive tools of their fate and transport in the environment. In this study, benzidine and DCB batch isotherms were developed and evaluated. The sediment samples were variable in composition, ranging from sandy to silty-clay sediment samples. The batch isotherms were then analyzed using high-performance liquid chromatography. Subsequently, a multiparameter model (MPM) that accounted for partitioning, covalent bonding, and cation exchange was developed and tested in an effort to understand the various mechanisms. Results proved the proposed model to be effective in predicting sorption of aromatic amines to lake sediments. The findings suggest that the MPM can provide a better understanding of the sorption process of aromatic amines than more conventional models.
Novel biomarkers of perchlorate exposure in zebrafish
Authors: Mukhi Sandeep , Carr James A. , Anderson Todd A. , Patiño Reynaldo 
Published: April 2005

Abstract
Perchlorate inhibits iodide uptake by thyroid follicles and lowers thyroid hormone production. Although several effects of perchlorate on the thyroid system have been reported, the utility of these pathologies as markers of environmental perchlorate exposures has not been adequately assessed. The present study examined time-course and concentration-dependent effects of perchlorate on thyroid follicle hypertrophy, colloid depletion, and angiogenesis; alterations in whole-body thyroxine (T4) levels; and somatic growth and condition factor of subadult and adult zebrafish. Changes in the intensity of the colloidal T4 ring previously observed in zebrafish also were examined immunohistochemically. Three-month-old zebrafish were exposed to ammonium perchlorate at measured perchlorate concentrations of 0, 11, 90, 1,131, and 11,480 ppb for 12 weeks and allowed to recover in clean water for 12 weeks. At two weeks of exposure, the lowest-observed-effective concentrations (LOECs) of perchlorate that induced angiogenesis and depressed the intensity of colloidal T4 ring were 90 and 1,131 ppb, respectively; other parameters were not affected (whole-body T4 was not determined at this time). At 12 weeks of exposure, LOECs for colloid depletion, hypertrophy, angiogenesis, and colloidal T4 ring were 11,480, 1,131, 90, and 11 ppb, respectively. All changes were reversible, but residual effects on angiogenesis and colloidal T4 ring intensity were still present after 12 weeks of recovery (LOEC, 11,480 ppb). Whole-body T4 concentration, body growth (length and weight), and condition factor were not affected by perchlorate. The sensitivity and longevity of changes in colloidal T4 ring intensity and angiogenesis suggest their usefulness as novel markers of perchlorate exposure. The 12-week LOEC for colloidal T4 ring is the lowest reported for any perchlorate biomarker in aquatic vertebrates.
Toxicity of α-, β-, (α+β)-endosulfan and their formulated and degradation products to Daphnia magna, Hyalella azteca, Oncophynchus mykiss, Oncophynchus kisutch, and biological implications in streams
Authors: Wan Michael T. , Kuo Jen-Ni , Buday Craig , Schroeder Grant , Van Aggelen Graham , Pasternak John 
Published: April 2005

Abstract
The static acute toxicities of α-endosulfan, β-endosulfan, (α + β)-endosulfan, endosulfan sulfate (their transformation product), and formulated materials were determined for a representative freshwater amphipod (Hyalella azteca), cladoceran (Daphnia magna), and salmonid fish (Oncorhynchus mykiss). Acute lethality tests also were conducted on these organisms and coho salmon (Oncorhynchus kisutch) by exposing them to simulated field water endosulfan concentrations, using either a single compound and/or in combinations. As well, growth/survival bioassays of H. azteca were carried out in simulated sediment endosulfan concentrations that were detected in farm ditches contiguous to fish streams in the Lower Fraser Valley (BC, Canada). All materials tested were very highly toxic to these nontarget aquatic indicator organisms. As the most potent compound, α-endosulfan is about 1.3, 6.6, and 58 times more toxic than the β-isomer to Daphnia, rainbow trout, and Hyalella, respectively. Some possible biological and toxicological implications of our findings are discussed in the context of endosulfan concentrations found in farm ditches flowing to fish streams in the Lower Fraser Valley.
Potentiation of the vitellogenic response to 17α-ethinylestradiol by cortisol in the fathead minnow Pimephales promelas
Authors: Brodeur Julie C. , Woodburn Kent B. , Klecka Gary M. 
Published: April 2005

Abstract
The effects of elevated plasma Cortisol levels on vitellogenin (VTG) induction were examined in the fathead minnow (Pimephales promelas) in an attempt to evaluate the potential influence of stress on this commonly used biomarker of estrogenicity. Two separate experiments were conducted in which fish plasma cortisol was elevated to various levels for 14 d by noninvasive additions of cortisol to the aquaria water. Fathead minnows were exposed to either cortisol alone, 17α-ethinylestradiol (EE2) alone, or a combination of the two hormones, and plasma levels of VTG as well as liver expression of VTG mRNA were measured. Both experiments gave similar results, with an exposure to 4 ng/L of EE2 resulting in significantly greater levels of plasma VTG in the presence of, compared to that in absence of, cortisol, whereas exposure to cortisol alone at concentrations between 144 and 800 μg/L had no effect on plasma VTG levels. This potentiation of the EE2-induced vitellogenesis by cortisol was dose-dependent, with plasma VTG reaching 125, 167, and 295% of the values obtained with EE2 alone when 144, 360, and 800 μg/L of cortisol, respectively, were added to the water. Liver mRNA results were consistent with plasma VTG, although they generally were more variable. The present study demonstrates that cortisol does not independently induce vitellogenesis but can potentiate estrogen-induced VTG synthesis in fathead minnow. The implications of these findings for the use of VTG as a biomarker of estrogenicity are discussed.
Multiple sublethal chemicals negatively affect tadpoles of the green frog, Rana clamitans
Authors: Boone Michelle D. , Bridges Christine M. , Fairchild James F. , Little Edward E. 
Published: April 2005

Abstract
Many habitats may be exposed to multiple chemical contaminants, particularly in agricultural areas where fertilizer and pesticide use are common; however, the singular and interactive effects of contaminants are not well understood. The objective of our study was to examine how realistic, sublethal environmental levels of ammonium nitrate fertilizer (0, 10, 20 mg/L and ammonium chloride control) and the common insecticide carbaryl (0 or 2.5 mg/L) individually and interactively affect the development, size, and survival of green frog (Rana clamitans) tadpoles. We reared tadpoles for 95 d in outdoor 1,000-L polyethylene ponds. We found that the combination of carbaryl and nitrate had a negative effect on development and mass of tadpoles compared to the positive effect that either contaminant had alone. Presence of carbaryl was generally associated with short-term increases in algal resources, including ponds exposed to both carbaryl and nitrate. However, with exposure to nitrate and carbaryl, tadpole mass and development were not positively affected as with one chemical stressor alone. The combination of these sublethal contaminants may reduce the ability of amphibians to benefit from food-rich environments or have metabolic costs. Our study demonstrates the importance of considering multiple stressors when evaluating population-level responses.
Comparative toxicity of two oil dispersants, superdispersant-25 and corexit 9527, to a range of coastal species
Authors: Scarlett Alan , Galloway Tamara S. , Canty Martin , Smith Emma L. , Nilsson Johanna , Rowland Steven J. 
Published: April 2005

Abstract
The acute toxicity of the oil dispersant Corexit 9527 reported in the literature is highly variable. No peer-reviewed data exist for Superdispersant-25 (SD-25). This study compares the toxicity of the two dispersants to a range of marine species representing different phyla occupying a wide range of niches: The marine sediment-dwelling amphipod Corophium volutator (Pallas), the common mussel Mytilus edulis (L.), the symbiotic snakelocks anemone Anemonia viridis (Forskål), and the seagrass Zostera marina (L.). Organisms were exposed to static dispersant concentrations for 48-h and median lethal concentration (LC50), median effect concentration (EC50), and lowest-observable-effect concentration (LOEC) values obtained. The sublethal effects of 48-h exposures and the ability of species to recover for up to 72 h after exposure were quantified relative to the 48-h endpoints. Results indicated that the anemone lethality test was the most sensitive with LOECs of 20 ppm followed by mussel feeding rate, seagrass photosynthetic index and amphipod lethality, with mussel lethality being the least sensitive with LOECs of 250 ppm for both dispersants. The results were consistent with current theory that dispersants act physically and irreversibly on the respiratory organs and reversibly, depending on exposure time, on the nervous system. Superdispersant-25 was found overall to be less toxic than Corexit 9527 and its sublethal effects more likely to be reversible following short-term exposure.
Uptake and accumulation of sediment-associated 4-nonylphenol in a benthic invertebrate (Lumbriculus variegatus, freshwater oligochaete)
Authors: Croce Valeria , De Angelis Silvia , Patrolecco Luisa , Polesello Stefano , Valsecchi Sara 
Published: April 2005

Abstract
In the present work, the oligochaete Lumbriculus variegatus was exposed for 56 d to lake sediment spiked with 4-nonylphenol (4-NP), which is a breakdown product of alkylphenol polyethoxylates, an important class of nonionic surfactants. During the exposure period, the content of 4-NP was determined in the oligochaetes, sediment, overlying water, and pore water in order to monitor the distribution of the 4-NP in the compartments of the test system. Concentration of 4-NP in L. variegatus increased linearly over the course of the test, with an uptake rate coefficient of 1.9 × 10−2 (± 0.2 × 10−2; [g carbon/(g lipid-h)]). No steady state was reached at the end of the exposure period, suggesting that the elimination of 4-NP by the organism was negligible. Ingested sediments played an important role in the accumulation of 4-NP in L. variegatus, which may achieve very high 4-NP body concentrations. The 56-d biota sediment accumulation factor (BSAF) was 24 ± 7 g carbon/g lipid. L. variegatus also was exposed to 4-NP-contaminated field sediment, and field oligochaetes and sediments were collected for 4-NP pollution assessment in aquatic ecosystem. The 4-NP uptake with natural sediment was in accordance with that measured with spiked sediments, suggesting that the bioavailability of sediment-associated 4-NP for L. variegatus was not affected by 4-NP sediment concentration and abiotic sediment characteristics. The BSAFs measured in field oligochaetes, ranging from 39 to 55 g carbon/g lipid, was relatively higher than the bioaccumulation factor measured in laboratory tests. The results suggest that 4-NP concentration can reach high levels in benthic oligochaetes; this can be an important way of exposure for their pelagic predators.
An in vitro study of the interaction of sea-nine® with rat liver mitochondria
Authors: Bragadin Marcantonio , Pavoni Bruno , Scutari Guido , Manente Sabrina 
Published: April 2005

Abstract
The interactions of the antifouling compound Sea-Nine® with rat liver mitochondria have been studied. The results indicate that low doses of this compound inhibit adenosine 5′-triphosphate (ATP) synthesis. Further investigations indicate that ATP synthesis inhibition should be due to an interaction of Sea-Nine with the succinic dehydrogenase in the mitochondrial respiratory chain.
Effects of bioturbation on cadmium transfer and distribution into freshwater sediments
Authors: Ciutat Aurélie , Anschutz Pierre , Gerino Magali , Boudou Alain 
Published: April 2005

Abstract
To investigate bioturbation effects on cadmium (Cd) fluxes from overlying water to sediments, indoor microcosms were developed. The bioturbating organisms were freshwater tubificid worms. Three experimental conditions were studied during 56 d. The three conditions were contaminated water column ([Cd]: 20 μg/L) with or without worms and uncontaminated water column with worms. Cadmium vertical profiles were determined in the pore water and in the sediments, based on six layers (0–0.5, 0.5–1, 1–2, 2–3, 3–5, 5–12 cm). Dissolved oxygen, manganese, sulfate, and particulate manganese were measured. Bioturbation was analyzed using conservative fluorescent particulate tracers. Bioturbation increased Cd flux into the sediments by close to a factor of two. Scavenging of Cd was more efficient in the bioturbated sediments because particles and adsorption sites for Cd were renewed at the sediment-water interface. Tubificids also increased the thickness of the Cd-enriched layer. Metals adsorbed on particles at the sediment surface were distributed by bioadvection, which predominated the mixing processes. Bioturbation also modified the vertical profiles of dissolved and particulate manganese and dissolved sulfate but not the profiles of dissolved oxygen. These results indicate that the advective transport of particles by bioturbation and their subsequent modification by redox reactions accelerates the trapping of metals in sediments.
Ecotoxicity of sodium fluoroacetate (compound 1080) to soil organisms
Authors: O'Halloran Kathryn , Jones Denise , Booth Lynn , Fisher Penny 
Published: April 2005

Abstract
Sodium fluoroacetate (compound 1080) is applied as a vertebrate pesticide in New Zealand for control of introduced mammalian pests. Despite its widespread use, little is known about the soil ecotoxicity of 1080. Therefore, the hazard of 1080 to soil invertebrates, plants, and soil microorganisms was evaluated in a series of controlled laboratory tests. No earthworm (Eisenia fetida) mortality was reported with 1080 exposures up to 865 mg/kg soil. The lowest-observable-effect concentration and the median effect level for earthworm reproduction were 100 and 90 mg/kg soil, respectively, for cocoon production and 100 and 160 mg/kg soil, respectively, for juvenile production. Lettuce (Lactuca sativa) was more sensitive than oats (Avena sativa) to 1080. Lettuce seedling emergence and seedling shoot growth were adversely affected at a soil concentration of 7 mg/kg. The presence of 1080 in soil at concentrations up to 1 g/kg soil did not affect the ability of soil microorganisms to mineralize nitrogen. Furthermore, nitrate mineralization was not inhibited in soil treated with the urine of 1080-poisoned possums (Trichosurus vulpecula). The data collectively indicate that 1080-related effects on soil organisms occur at levels well above those that have been measured in soil (&lt;0.1 mg/kg) following application of 1080 in baits for vertebrate pest control in New Zealand.