bluuebunny/crossref_metadata_2025_split huggingface dataset:
The role of ultraviolet-adaptation of a marine diatom in photoenhanced toxicity of acridine
Authors: Wiegman Saskia , Barranguet Christiane , Spijkerman Elly , Kraak Michiel Harm Steven , Admiraal Wim 
Published: March 2010

AbstractCultures of the marine diatom Phaeodactylum tricornutum were grown under laboratory light with a different fraction of ultraviolet radiation (UV) to study the potential role of photoadaptation in determining the sensitivity to photoenhanced toxicity of acridine. In short-term experiments, a higher acridine concentration was needed to inhibit the photosynthetic electron flux, monitored with chlorophyll a fluorescence, in algae exposed to fluorescent light (low UV) than to mercury light (high UV), consistent with the expected role of UV. The two types of light in long-term exposures led to changes in the pigment composition and photosystem I (PS I) to photosystem II (PS II) stoichiometry to optimize the utilization of fluorescent and mercury light. Despite the adaptation of the photosynthetic apparatus to a small fraction of UV, long-term exposure to mercury light did show a constant sensitivity of the photosynthetic efficiency of P. tricornutum to the phototoxic acridine. It is concluded that the prime receptor of photoenhanced toxicity may be unrelated to the photosynthetic machinery.
Failure of the biotic ligand and free-ion activity models to explain zinc bioaccumulation by Chlorella kesslerii
Authors: Hassler Christel S. , Wilkinson Kevin J. 
Published: March 2010

Abstract
Zinc accumulation by Chlorella kesslerii (Chlorophycee) was studied for [Zn2+] ranging from 4 pM to 1 mM. A first-order uptake flux as predicted by the free ion activity model (FIAM) and the biotic ligand model (BLM) was not observed. Furthermore, when algae were preconditioned in slightly limiting (10 pM) versus optimal (1 nM) free zinc concentrations, the internalization flux increased and was nearly constant over the range of [Zn2+] examined. This observation was attributed to the synthesis of membrane-bound zinc transporters. Neither solution Zn chemistry nor surface-bound Zn was a good predictor of Zn uptake fluxes. Several hypotheses were examined to explain the failure of the steady-state uptake models. Although zinc excretion and a Zn diffusion limitation were observed, neither result could explain the majority of observed deviation from the models. Bioaccumulation experiments performed with inhibitors (vanadate and carbonyl cyanide m-chlorophenylhydrazone [CCCP]) demonstrated clearly that zinc transport is an energy-dependent process in Chlorella kesslerii. The presence of an active transport signifies that Zn uptake may function independently of the electrochemical Zn gradient and that, in some cases, both uptake fluxes and receptor-bound Zn may be independent of solution chemistry.
Effects of sublethal concentrations of atrazine and nitrate on metamorphosis of the African clawed frog
Authors: Sullivan Karen Brown , Spence Karla M. 
Published: March 2010

Abstract
Tadpoles of the African clawed frog (Xenopus laevis) were exposed to sublethal concentrations of atrazine (0, 40, and 320 μg/L) and nitrate (0, 37, and 292 mg/L) from feeding stage to metamorphosis. A 3 × 3 factorial design was used to identify both single and interactive effects. At metamorphosis, tadpole weight, snout–vent length (SVL), and hematocrit were determined. Mean mortality was greater in tanks receiving 320 μg/L atrazine; nitrate had no effect on mortality. Significant differences for all mean traits at metamorphosis occurred among atrazine treatments; higher atrazine exposure increased time to metamorphosis and decreased weight, SVL, and hematocrit. Nitrate treatments were not significantly different. Significant interaction tests between atrazine and nitrate occurred for weight and SVL at metamorphosis; the specific type of interaction varied among treatments. Assuming an additive mixture model, at low atrazine (40 μg/L), the addition of 37 mg/L nitrate produced SVL values less than expected (a synergistic effect) while the addition of 292 mg/L nitrate yielded SVL values greater than expected (an antagonistic effect). A similar response was noted for tadpoles in the 320-μg/L atrazine treatments. These results indicate that environmentally realistic concentrations of atrazine exert a negative impact on amphibian metamorphosis. Also, this study suggests that mixtures of agricultural chemicals, even if sublethal, may exert negative and not necessarily consistent mixture effects.
Photoenhanced toxicity of aqueous phase and chemically dispersed weathered Alaska North Slope crude oil to Pacific herring eggs and larvae
Authors: Barron Mace G. , Carls Mark G. , Short Jeffrey W. , Rice Stanley D. 
Published: March 2010

AbstractThe photoenhanced toxicity of weathered Alaska North Slope crude oil (ANS) was investigated in the eggs and larvae of Pacific herring (Clupea pallasi) with and without the chemical dispersant Corexit® 9527. Oil alone was acutely toxic to larvae at aqueous concentrations below 50 μg/L total polycyclic aromatic hydrocarbons (tPAH), and median lethal (LC50s) and effective concentrations (EC50s) decreased with time after initial oil exposure. Brief exposure to sunlight (∼2.5 h/d for 2 d) significantly increased toxicity 1.5- to 48-fold over control lighting. Photoenhanced toxicity only occurred when oil was present in larval tissue and increased with increasing tPAH concentration in tissue. Ultraviolet radiation A (UVA) treatments were less potent than natural sunlight, and UVA + sunlight caused greater toxicity than sunlight alone. The toxicity of chemically dispersed oil was similar to oil alone in control and UVA treatments, but oil + dispersant was significantly more toxic in the sunlight treatments. The chemical dispersant appeared to accelerate PAH dissolution into the aqueous phase, resulting in more rapid toxicity. In oil + dispersant exposures, the 96-h no-observed-effect concentrations in the UVA + sunlight treatment were 0.2 μg/L tPAH and 0.01 μg/g tPAH. Exposure of herring eggs to oil caused yolk sac edema, but eggs were not exposed to sun and UVA treatment did not cause phototoxicity. These results are consistent with the hypothesis that weathered ANS is phototoxic and that UV can be a significant and causative factor in the mortality of early life stages of herring exposed to oil and chemically dispersed oil.
Dynamics of organochlorine pesticides in soils from a southeastern region of Argentina
Authors: Miglioranza Karina S. B. , Aizpún de Moreno Julia E. , Moreno Víctor J. 
Published: March 2010

Abstract
Monitoring of organochlorine pesticides (OCPs) was carried out to identify andquantify the contribution of point and nonpoint sources to the total OCP flux in a southeastern region of Argentina. Natural, recreational, and agricultural soils located in the surrounding of a lagoon were analyzed by gas chromatography with electron-capture detector. Physical and chemical characteristics (texture, humidity, and organic matter content) were determined at different depths (0–15 cm, 15–30 cm, and 45–55 cm). The pattern of OCP distribution was similar in all soil sampled, with DDT and metabolites &gt; hexachlorocyclohexanes (HCHs) &gt; heptachlor &gt; chlordanes. The highest values of OCPs (656.1 ng/g dry wt) were found in the surface natural soil despite its never having received direct OCP application. This would be mainly due to the high organic matter content of the surface natural soils as well as its topographic position (highland hills), with main winds arriving from agricultural areas. Microorganism abundance and edaphic biota in the upper layer would justify the high levels of metabolites found. The agricultural soil (intensive tillage) also showed the highest OCP values (30.19 ng/g dry wt) in the surface horizon. Because of management practices, volatilization could have been one of the major causes of pesticide loss from this target area. Recreational soil showed the lowest OCP levels in the surface layer because of weathering that occurs when the nearby lagoon floods this zone. Our results show that, although most of these pesticides are banned, they are present in these soils and the atmospheric transport and deposition would be the major processes for distributing OCPs from target to natural areas.
Degradation of nonylphenol in spiked soils and in soils treated with organic waste products
Authors: Mortensen Gerda Krog , Kure Liv Kerstin 
Published: March 2010

Abstract
Widespread application of sewage sludge to agricultural soils in Denmark has led to concern about the accumulation and effects of nonylphenol (NP) in the soil ecosystem. We have thus studied the degradation of NP and possible uptake in agricultural plants in greenhouse pot experiments. Different waste products including anaerobic and aerobic sludge, compost, and pig manure were incorporated into a sandy soil. In addition, NP was used to spike soil to known concentrations. Rape (Brassica napus L. cv Hyola 401) was sown in the pots and harvested after 30 d. In order to investigate the influence of plant growth on the degradation, plant-free pots were established. The concentrations in the soil were between 13 and 534 ppb dry weight. No plant uptake was observed above the detection limit at 100 ppb dry weight. When NP was added as waste to the soil, plant growth significantly stimulated the degradation. In experiments with anaerobic and aerobic sludge, respectively, 13 and 8.3% of NP remained in the soil from pots planted with rape compared with 26 and 18% in soil without plant growth. When NP was added as a spike to soil, the degradation was more complete and plant growth did not influence the degradation. Percentages of 2.2 and 1.8 were still in the soil at harvest for planted and plant-free pots, respectively. The degradation of NP was more extensive in sludge-amended soil compared with compost.
Heterogeneous photochemical reactions of decabromodiphenyl ether
Authors: Hua Inez , Kang Namgoo , Jafvert Chad T. , Fábrega-Duque José R. 
Published: March 2010

AbstractBrominated diphenyl ethers area major class of brominated flame retardants, with production of decabromodiphenyl ether (DBDPE) contributing significantly to this total. Although little is known about the mechanisms and rates of DBDPE decay in the natural environment, photochemical transformation is often suggested as a potentially important fate process. In this study, photochemical reactions of DBDPE precipitated onto hydrated surfaces (quartz glass, silica particles, and humic acid-coated silica particles) were measured. Decabromodiphenyl ether was irradiated within a Rayonet photochemical reactor equipped with lamps having maximum emissions (Λmax) at 300 or 350 nm or with sunlight (West Lafayette, IN, USA at 40°26′N, 86°55′W). When DBDPE is plated onto quartz tubes and hydrated with reagent-grade water, phototransformation occurred over a period of days with each light source. With two lamps (Λmax = 300 nm), about 31% of the initial mass of DBDPE remained after 60 h in the Rayonet reactor. Decabromodiphenyl ether transformed more slowly when irradiated by sunlight, with 30% of the initial compound recovered from tubes after 72 h. In the presence of humic acid (HA) solution, transformation of DBDPE by solar irradiation is slowed even further: approximately 70% remained after 72 h. Solar irradiation of DBDPE adsorbed to humic acid-coated sand particles resulted in the slowest irradiation rates; approximately 88% of the initial mass was recovered after 96 h of exposure. Although the parent compound exhibited slow transformation, analysis by high-performance liquid chromatography (HPLC) indicated some accumulation of transformation products.
Histopathology as a tool for the evaluation of endocrine disruption in zebrafish (Danio rerio)
Authors: van der Ven Leo T. M. , Wester Piet W. , Vos Jeff G. 
Published: March 2010

Abstract
The importance of histology as a tool in the evaluation of endocrine disruption in fish depends on the choice and interpretation of appropriate endpoints, as is illustrated by the analysis of the effects of exposure to the estrogen 17β-estradiol (E2) and the nonaromatizable androgen 17-methyldihydrotestosterone (MDHT). The E2 led to the disappearance of vitellogenic oocytes in the ovary and an increased area of relatively large, eosinophilic cells in the testis, which were identified as spermatogonia under high-power magnification; this was a relative increase, as was shown by histomorphometry, because of a decreased size of spermatogenic cysts and a relative decrease of spermatocyte cysts. The E2 also induced an accumulation of acidophilic fluid in vessels and interstitial spaces, confirmed by immunohistochemistry as vitellogenin, and basophilia in the liver also associated with the production of vitellogenin. The MDHT induced activation of Sertoli cells in the testis and a decreased presence of vitellogenic oocytes and a reduced growth of previtellogenic oocytes in the ovary. These observations indicate the advantages of examining multiple organ systems on whole-body sections and the application of adequate magnifications. Inclusion of additional techniques such as morphometry and immunohistochemistry is valuable to further uncover insidious effects of endocrine disruptors.
Pesticide risk assessment in a lagoon ecosystem. Part II: Effect assessment and risk characterization
Authors: Villa Sara , Vighi Marco , Casini Silvia , Focardi Silvano 
Published: March 2010

Abstract
Ecotoxicological risk assessment for pesticides was performed on a coastal lagoon ecosystem (Orbetello lagoon, central Italy) according to the procedure described in the European technical guidance document (TGD) on risk assessment for new and existing substances. The procedure was applied to individual chemicals and to a mixture of chemicals with the same toxicological mode of action. Biomarker studies, measuring acetylcholinesterase (AchE) activity inhibition, were conducted on Zosterisessor ophiocephalus to compare the results of theoretical risk assessment with experimental measurements of ecotoxicological stress. Value and limitations of the risk assessment procedure and its application to site-specific environmental conditions are discussed. A tool crop risk index (CRI) for assessing the overall impact of pesticide use on a crop is proposed.
Ecotoxicology and spatial modeling in population dynamics: An illustration with brown trout
Authors: Chaumot Arnaud , Charles Sandrine , Flammarion Patrick , Auger Pierre 
Published: March 2010

Abstract
We developed a multiregion matrix population model to explore how the demography of a hypothetical brown trout population living in a river network varies in response to different spatial scenarios of cadmium contamination. Age structure, spatial distribution, and demographic and migration processes are taken into account in the model. Chronic or acute cadmium concentrations affect the demographic parameters at the scale of the river range. The outputs of the model constitute population-level end points (the asymptotic population growth rate, the stable age structure, and the asymptotic spatial distribution) that allow comparing the different spatial scenarios of contamination regarding the demographic response at the scale of the whole river network. An analysis of the sensitivity of these end points to lower order parameters enables us to link the local effects of cadmium to the global demographic behavior of the brown trout population. Such a link is of broad interest in the point of view of ecotoxicological management.
Bioconcentration and acute toxicity of polycyclic musks in two benthic organisms (Chironomus ripariusandLumbriculus variegatus)
Authors: Artola-Garicano Elsa , Sinnige Theo L. , van Holsteijn Ineke , Vaes Wouter H. J. , Hermens Joop L. M. 
Published: March 2010

AbstractIn the current study, the bioconcentration behavior and acute toxicity of two polycyclic musks, Tonalide® 7-acetyl-1,1,3,4,4,6,-hexamethyl-1,2,3,4,-tetrahydronaphthalene (AHTN) and Galaxolide® 1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexa-methyl-cyclopenta[γ]-2-benzopyran (HHCB), were studied in two benthic organisms. Polycyclic musks are frequently used fragrances, and they have been detected in different compartments of the environment. The aim of this study was to fill some empirical data gaps for AHTN and HHCB for benthic organisms. Results show that differences exist between both organisms. Chironomus riparius exhibited bioconcentration factors (BCFs) for AHTN and HHCB substantially lower than predicted for nontransformed organics. The BCFs for both chemicals increased after coexposure of the organism to the cytochrome P450 inhibitor piperonyl butoxide. Thus, the low BCF values were the result of rapid biotransformation of AHTN and HHCB in the midge larvae. Bioconcentration kinetics indicated that both chemicals induced their own cytochrome P450–mediated metabolism. Acute toxicity of AHTN to midge larvae was reduced compared to predicted baseline toxicity and was similar for HHCB. Bioconcentration of AHTN and HHCB in the worm (Lumbriculus variegatus) is in agreement with predictions based on the octanol-water partition coefficients of these chemicals. Acute toxicity was found to be similar to predicted values for baseline toxicity. Summarizing, for AHTN and HHCB, acute toxicity and bioconcentration behavior in L. variegatus was in accordance with predicted data for nontransformed organics. In C. riparius, bioconcentration as well as toxicity were reduced.
Breeding performance of great tits (Parus major) along a gradient of heavy metal pollution
Authors: Sens Ellen Jans , Dauwe Tom , Pinxten Rianne , Eens Marcel 
Published: March 2010

Abstract
The possible effects of heavy metal pollution on various breeding parameters of the great tit (Parus major) were studied at four study sites in a pollution gradient near a large nonferrous smelter in Belgium during three consecutive breeding seasons. Significantly more females interrupted their laying period near the pollution source than did females farther away. At the two most polluted sites, hatching success was significantly reduced compared to two lesser-polluted study sites. Overall breeding success was also significantly lower toward the factory complex. This lowered breeding success was caused not only by the decreased hatching success toward the pollution source but also by the significant difference in fledging success among sites. Although a clear relationship was observed between the exposure to heavy metal pollution and an impaired reproduction, not all reproductive parameters were affected. We found no significant differences in the onset of laying, clutch size, length of the incubation period, and the proportion of nests with low-quality eggs among sites. Although nest box occupancy was every year slightly lower toward the smelter compared to farther away, differences among study sites were never significant.
Influence of aging on copper bioavailability in soils
Authors: Lock Koen , Janssen Colin R. 
Published: March 2010

AbstractBecause of long-term chemical processes, metal bioavailability in field soils decreases with time. Metal toxicity may, therefore, be overestimated if toxicity data with freshly spiked soils are used to derive soil quality criteria, a current practice. In the present study, effects of the long-term processes, called aging, on copper partitioning and ecotoxicity are investigated. Twenty-five field soils contaminated by copper runoff from bronze statues and 25 uncontaminated control soils sampled at 5-m distance from these statues were collected in Flanders (Belgium). The soils were selected so that parameters affecting copper bioavailability (pH, cation-exchange capacity, organic matter content, etc.) varied considerably. To assess the effect of aging on copper toxicity, control soils were spiked at total copper concentrations comparable to those of historically contaminated soils. Pore-water copper concentrations and 0.01 M CaCl2–extracted copper concentrations were significantly higher in freshly spiked soils compared to contaminated field soils. However, this could be a pH effect, because pH decreased after spiking. Acute toxicity to Enchytraeus albidus (14 d) as well as chronic toxicity to Folsomia candida (28-d reproduction) and Trifolium pratense (14-d growth) indicated a dose-response relationship between copper toxicity and pore-water copper concentration or the CaCl2-extracted copper fraction.
A thermodynamics-based estimation model for adsorption of organic compounds by carbonaceous materials in environmental sorbents
Authors: van Noort Paul C. M. 
Published: March 2010

Abstract
A model was developed to estimate Langmuir affinities for adsorption of low-polarity organic compounds from either water or air by carbonaceous sorbents. Sorption enthalpies and entropies provided the basic information for the description of sorption affinities in terms of the entropy of melting and either solubility in water or vapor pressure. For m-xylene, polycyclic aromatic hydrocarbons (PAHs) and chlorobenzenes on 10 different sorbents, 80% of the measured sorption affinities fall within a factor of four of the model estimates. Equations for the limiting distribution coefficients in terms of either octanol—air (KOA) or octanol—water partition (Kow) coefficients were derived from regressions of calculated affinities combined with an estimated relation between experimental Langmuir sorption capacities and Kow. Estimated soot—water distribution coefficients were within a factor of three of measured data for polychlorobiphenyls (PCBs) and lower molecular weight PAHs on automotive soot samples and captured the dependence of PCB distribution coefficients on the extent of ortho substitution. For higher molecular weight PAHs, sorption was underestimated. For soot in sediment—water distribution coefficients of PAHs and PCBs, estimated values captured both the trend of measured data with Kow and the dependence on sorbate planarity. Tentative application to aerosol—air distribution explained the observed independence of distribution coefficient–KOA relations for PCBs on the extent of ortho substitution and suggested nonequilibrium conditions for PAHs in comparison with recent measurements.