bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evaluation of theGammarus pulexin situ feeding assay as a biomonitor of water quality: Robustness, responsiveness, and relevance
Authors: Maltby Lorraine , Clayton Sophie A. , Wood Robert M. , McLoughlin Nathan 
Published: March 2010

AbstractBiomonitoring using benthic macroinvertebrates has been used to assess water quality in Europe since the early 20th century. Most methods use community-level measurements, and the use of single-species responses has been limited, despite their potential benefits as sensitive, early warning indicators. Here we evaluate a single-species in situ assay in which the response is feeding inhibition of the freshwater amphipod Gammarus pulex. The assay was deployed in uncontaminated reference sites to quantify background variability in feeding rates and to elucidate sources of this variation. The ability of the assay to detect impacts of point-source discharges was assessed and the ecological relevance of the assay determined by comparing assay responses to aspects of community structure and functioning. Water temperature accounted for 76% of the variation in the feeding rate of animals deployed at uncontaminated sites, and summer deployments had a &gt;90% power to detect a 30% inhibition in feeding. Inhibition of the situ feeding rate of G. pulex deployed downstream of a variety of point-source discharges ranged from 27 to 99.6%. Gammarus pulex is an important detritivore in stream communities, and a strong positive correlation existed between in situ feeding rate measured over 6 d and leaf decomposition measured over 28 d. A positive correlation also existed between in situ feeding and macroinvertebrate diversity and a biotic index. The G. pulex in situ feeding assay is a short-term sublethal biomonitor of water quality that is indicative of community- and ecosystem-level responses occurring over longer time periods. It is robust, responsive, and relevant.
Morphological plasticity in metal-sequestering earthworm chloragocytes: Morphometric electron microscopy provides a biomarker of exposure in field populations
Authors: Morgan A. John , Turner Michael P. , Morgan John E. 
Published: March 2010

AbstractMorphometric measurements of the volume fractions (Vv) of two prominent metal-sequestering compartments, chloragosome granules and debris vesicles, were made on transmission electron micrographs of chloragocytes in Dendrodrilus rubidus (Annelida: Oligochaeta: Lumbricidae) from one uncontaminated site and three qualitatively and quantitatively different metalliferous soils associated with disused Pb/Zn mines. We also examined the relative volume fractions of the alimentary wall and attached chloragogenous tissue by light microscopy. Several conclusions relevant to environmental diagnostics were reached: Metal identity and degree of soil pollution exert strong effects on chloragocyte ultrastructure; morphometry by light microscopy indicated that the metal-induced structural effects are characterized by intracellular alterations not accompanied by a significant expansion of the tissue volume; elevated metal burdens can reduce chloragosome Vv and, concomitantly, increase the Vv of their autophagic derivatives, the debris vesicles; the measured cellular alterations were more closely correlated with integrated tissue metal burdens than they were with integrated soil metal burdens; and estimates of tissue metal distribution, derived by combining morphometric data and published whole-worm and chloragosome metal concentrations, suggested that the alimentary wall of earthworms may sequester Pb, Zn, and Cd. Our study shows that cellular changes, directly or indirectly, may yield quantifiable expressions of metal loads bioaccumulated by earthworms. However, the practical use of cellular changes as biomarkers of soil quality probably will require automated light-microscopic morphometry in combination with organelle-specific molecular probes to be cost effective.
Evaluation of the AgDISP aerial spray algorithms in the AgDRIFT model
Authors: Bird Sandra L. , Perry Steven G. , Ray Scott L. , Teske Milton E. 
Published: March 2010

AbstractA systematic evaluation of the AgDISP algorithms, which simulate off-site drift and deposition of aerially applied pesticides, contained in the AgDRIFT® model was performed by comparing model simulations to field-trial data collected by the Spray Drift Task Force. Field-trial data used for model evaluation included 161 separate trials of typical agriculture aerial applications under a wide range of application and meteorological conditions. Input for model simulations included information on the aircraft and spray equipment, spray material, meteorology, and site geometry. The model input datasets were generated independently of the field deposition results, i.e., model inputs were in no way altered or selected to improve the fit of model output to field results. AgDRIFT shows a response similar to that of the field observations for many application variables (e.g., droplet size, application height, wind speed). However, AgDRIFT is sensitive to evaporative effects, and modeled deposition in the far-field responds to wet bulb depression whereas the field observations did not. The model tended to overpredict deposition rates relative to the field data for far-field distances, particularly under evaporative conditions. AgDRIFT was in good agreement with field results for estimating near-field buffer zones needed to manage human, crop, livestock, and ecological exposure.
Effect of initial cell density on the bioavailability and toxicity of copper in microalgal bioassays
Authors: Franklin Natasha M. , Stauber Jennifer L. , Apte Simon C. , Lim Richard P. 
Published: March 2010

AbstractAlgal toxicity tests based on growth inhibition over 72 h have been extensively used to assess the toxicity of contaminants in natural waters. However, these laboratory tests use high cell densities compared to those found in aquatic systems in order to obtain a measurable algal response. The high cell densities and test duration can result in changes in chemical speciation, bioavailability, and toxicity of contaminants throughout the test. With the recent application of flow cytometry to ecotoxicology, it is now possible to use lower initial cell densities to minimize chemical speciation changes. The speciation and toxicity of copper in static bioassays with the tropical freshwater alga Chlorella sp. and the temperate species Selenastrum capricornutum (Pseudokirchneriella subcapitata) were investigated at a range of initial cell densities (102-105 cells/ml). Copper toxicity decreased with increasing initial cell density. Copper concentrations required to inhibit growth (cell division) rate by 50% (72-h median effective concentration [EC50]) increased from 4.6 to 16 μg/L for Chlorella sp. and from 6.6 to 17 μg/L for S. capricornutum as the initial cell density increased from 102 to 105 cells/ml. Measurements of anodic stripping voltammetry—labile, extracellular, and intracellular copper confirmed that at higher initial cell densities, less copper was bound to the cells, resulting in less copper uptake and lower toxicity. Chemical measurements indicated that reduced copper toxicity was due primarily to depletion of dissolved copper in solution, with solution speciation changes due to algal exudates and pH playing a minor role. These findings suggest that standard static laboratory bioassays using 104 to 105 algal cells/ml may seriously underestimate metal toxicity in natural waters.
Extractable substances (anionic surfactants) from membrane filters induce morphological changes in the green algaScenedesmus obliquus(Chlorophyceae)
Authors: Lürling Miquel , Beekman Wendy 
Published: March 2010

AbstractThe effect of filtration of medium through different kinds of filters (glass fiber, mixed esters of cellulose and nitrocellulose) on the morphology in the green alga Scenedesmus obliquus was examined. Several compounds potentially released from membrane filters were further investigated, and among them, two anionic surfactants were found to be morphologically active. Exposure to the anionic surfactants resulted within 2 d in the transformation of unicellular populations of Scenedesmus in populations dominated by colonies. Growth rates between control and surfactant-exposed populations were identical, and the morphological effect occurred at surfactant concentrations far below the reported no-observed-effect concentration for growth inhibition, stressing the need for inclusion of morphological appearance of Scenedesmus in algal toxicity testing to improve the assessment of ecological risks.
Development and validation of models predicting the toxicity of major seawater ions to the mysid shrimp, Americamysis bahia
Authors: Pillard David A. , Dufresne Doree L. , Mickley Mike C. 
Published: March 2010

Abstract
The concentration and balance of major ions that comprise total dissolved solids (TDS) can influence the toxicity of effluents discharged to freshwater and marine environments. An additional complicating factor in waters released to saltwater systems is the effluent salinity since the toxicity of major ions changes with the salinity of the test solution. A study was conducted to evaluate the toxicity of six major seawater ions (bicarbonate, borate, calcium, magnesium, potassium, and sulfate) to the mysid shrimp, Americamysis bahia, at salinities of 10 and 20%. Logistic regression models were developed to predict organism survival at deficient and excess concentrations of the ions. Calcium and potassium caused significant mortality to mysid shrimp in both excess and deficient (relative to artificial seawater) solutions. Bicarbonate, borate, and magnesium displayed significant toxicity only in excess concentrations, while sulfate had no adverse impacts at any of the concentrations tested. As the salinity of the test solutions decreased, mysid shrimp tolerated increasingly lower calcium and potassium concentrations. Similarly, as salinity increased, the upper tolerance levels of calcium, potassium, and magnesium also increased. The models developed during these studies, and similar models developed by other researchers, were used to evaluate 11 actual effluents with unexplained toxicity that might be associated with TDS ions. The models correctly identified calcium as the primary toxicant in 9 of the 11 effluents. These results indicate the models can be used as an important tool to identify toxicity associated with major seawater ions.
Kinetic uptake of bioavailable cadmium, selenium, and zinc byDaphnia magna
Authors: Yu Ri-Qing , Wang Wen-Xiong 
Published: March 2010

AbstractKinetic uptake of Cd, Se(IV), and Zn by Daphnia magna from the dissolved phase was determined using radiotracer techniques in moderately hard water. The metal influx rate and distribution in the soft tissue and the exoskeleton of the daphnids as influenced by metal concentration, inorganic ligands including pH, Ca2+ and SO42−, and body size were quantified. When the metal concentrations were &lt;180 nM for Cd and &lt;769 nM for Zn, the concentration factor in daphnids increased linearly within the 12 h of exposure. At a higher concentration, apparent steady state was reached after 3 h of exposure. Cadmium and Zn distribution in the soft tissues was not affected by the total ambient concentrations, whereas Se distribution in the soft tissue decreased by 7 to 10% with increasing Se concentration from 16 to 643 nM. A linear positive power relationship was found between the influx rates of the metals and the ambient concentrations. The concentration factor for Se, however, decreased significantly with increasing Se concentration in water. The influx rate of metals was inversely related to the body size in a power function. When the pH in ambient water increased from 5.0 to 7.0, the influx rate of Cd, Se, and Zn increased by 2.9, 16.6, and 4.1 times, respectively. The influx rates of Cd, Se, and Zn decreased by 6.9, 8.7, and 4.4 times, respectively, with an increase in Ca2+ concentration from 0.6 to 5.1 mM. In contrast, the uptake rates of all three metals were not significantly affected by the SO42− concentration. The majority of accumulated Se was distributed in the soft tissues after 12 h of exposure, whereas Cd and Zn were about evenly distributed in the soft tissue and exoskeleton. Any changes in pH, Ca2+, and SO42− concentrations did not apparently affect their distributions in the daphnids. Our study provides important kinetic data necessary for delineating the exposure routes and for further development of the biotic ligand model in Daphnia. Using a bioenergetic-based kinetic model, we showed that the dissolved uptake is dominant for Zn accumulation (&gt;50%). For Cd and Se, dietary exposure is dominant when the bioconcentration factors of these metals in phytoplankton are at the high end.
Mercury uptake and enzymatic response ofPosidonia oceanicaafter an experimental exposure to organic and inorganic forms
Authors: Ferrat Lila , Bingert Aurelie , Roméo Michele , Gnassia-Barelli Mauricette , Pergent-Martini Christine 
Published: March 2010

AbstractThe aim of this study was to examine the experimental uptake of mercury and the enzymatic response, i.e., glutathione S-transferase (GST) activity, to this metal introduced into the medium under organic (methylmercury chloride) and nonorganic (mercury chloride) forms. Shoots of Posidonia oceanica were collected in a nonpolluted area in the northwestern Mediterranean Sea and were treated in aquaria with increasing mercury concentrations/exposure times (48, 96, and 144 h). Compared with the controls, a significant uptake was noted in the blades contaminated by HgCl2, whereas in the sheaths, a significant decrease of total mercury was noted. The blades exposed to CH3HgCl exhibited higher mercury concentrations than the controls; after 144 h exposure to organic mercury, the levels found in the blades were approximately sevenfold the values of the controls. The uptake noted in the sheaths treated with organic mercury followed the same pattern as with HgCl2 (decreased value compared with the controls) except after 144 h, where a slight increase in mercury was found in this tissue. The percentage of organic mercury in controls and treated blades and sheaths (treatment with both forms of mercury) represented always more than 50% of the total mercury in the plant. Glutathione S-transferase activities were significantly increased in the blades and sheaths of P. oceanica exposed to mercury chloride, whereas exposure to methylmercury was not significant. The presence of a GST isoform of 31 kDa was demonstrated by immunochemical methods (Western blotting) in the sheaths but not in the blades of the phanerogam.
Effect of xenoestrogen exposure on the expression of cytochrome P450 isoforms in rainbow trout liver
Authors: Katchamart Sirinmas , Miranda Cristobal L. , Henderson Marilyn C. , Pereira Clifford B. , Buhler Donald R. 
Published: March 2010

AbstractWe studied the estrogenic effects of model chemicals in one-year-old juvenile rainbow trout. Methoxychlor (20 mg/kg), diethylstilbestrol (15 mg/kg), 4-tert-octylphenol (25 and 50 mg/kg), and biochanin A (25 and 50 mg/kg) were injected intraperitoneally on days 1, 4, and 7. Fish were sacrificed on day 9 and examined for multiple biomarkers. All of the test chemicals caused increases in plasma vitellogenin levels, a biomarker of estrogenicity. Treatment with the xenoestrogens decreased hepatic lauric acid hydroxylase activity and, as shown by Western blots, also generally reduced expression of hepatic cytochrome P450s 2K1 (CYP2K1), 2M1 (CYP2M1), and 3A27 (CYP3A27) at the protein level. Both doses of biochanin A also significantly induced P4501A (CYP1A) and greatly increased hepatic 7-ethoxyresorufin-O-deethylase (EROD) activity. These findings suggest that methoxychlor, diethylstilbestrol, 4-tert-octylphenol, and biochanin A were all estrogenic and mimicked 17b-estradiol (E2) in repressing the expression of cytochrome P450 isoforms (CYP2K1, CYP2M1, and CYP3A27) in the rainbow trout liver. Additionally, biochanin A was found to induce CYP1A in this fish species.
Turtle sex determination assay: Mass balance and responses to 2,3,7,8-tetrachlorodibenzo-p-dioxin and 3,3′,4,4′,5-pentachlorobiphenyl
Authors: Gale Robert W. , Bergeron Judith M. , Willingam Emily J. , Crews David 
Published: March 2010

AbstractPolyhalogenated hydrocarbons have been implicated in the anomalous sexual differentiation of mammals and reptiles. Here, a temperature-sensitive turtle sex determination assay using the red-eared slider (Trachemys scripta elegans) was used to determine the estrogenic or antiestrogenic activity of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and 3,3′,4,4′,5-pentachlorobiphenyl (PCB-126). Neither TCDD nor PCB-126 showed a statistically significant difference in the resulting sex ratios (Fisher's exact test, p &lt; 0.45). As a consequence of the dosing technique (eggshell spotting), the shell retained 90 and 96% of the dose for PCB-126 and TCDD, respectively, similar to retention of estradiol-17β. However, the dosing allowed transfer of sufficient chemical to achieve tissue concentrations that were greater than most concentrations reported for environmentally incurred residues. Similar relative mass distributions of PCB-126 and TCDD were observed in albumin (14–20%), yolk (55–70%), and embryo (16–25%). Relative concentration distributions in the embryo approached those in the yolk, 37 to 40% and 40 to 52%, respectively, while relative concentrations in the albumin remained at 11 to 20%. Lipid-normalized TCDD and PCB-126 concentrations were 30- to 40-fold greater in the embryo than in the yolk. It is hypothesized that nonpassive partitioning processes may have occurred in the embryo.
An ecological risk assessment for triclosan in lotic systems following discharge from wastewater treatment plants in the United States
Authors: Reiss Richard , Mackay Neil , Habig Cliff , Griffin John 
Published: March 2010

Abstract
A modeling study was conducted to examine the distribution of concentrations of the antimicrobial triclosan (2,4,4′-trichloro-2′-hydroxydiphenyl ether) in rivers following discharge from wastewater treatment plants (WWTPs). Most uses of triclosan are disposed of down residential drains and ultimately reach WWTPs. A modeling analysis was conducted to simulate the discharge of triclosan in WWTP effluents to rivers and calculate the expected concentrations based on characteristics of the reach where the discharge occurred, the estimated concentration of triclosan in the WWTP effluent, and the physicochemical properties of triclosan. A probabilistic exposure assessment was conducted based on data on the characteristics of U.S. reaches receiving wastewater discharges and the physicochemical characteristics of triclosan. A risk assessment was conducted by comparing the estimated concentrations with toxicity endpoint concentrations for species representative of key ecological groups. For fish and invertebrates, neither acute nor chronic risks are of concern, and no concerns exist for vascular aquatic plants. However, certain types of algae are the most sensitive species to triclosan by more than an order of magnitude than other algal or aquatic plant species. For these algae, the potential exists for some risk from triclosan exposure near the WWTP discharge location during low-flow-rate periods for some WWTPs with small dilutions. The risks downstream are lower because of dissipation of triclosan.
Concentration-dependent kinetics of pollutant desorption from soils
Authors: Braida Washington J. , White Jason C. , Zhao Dongye , Ferrandino Francis J. , Pignatello Joseph J. 
Published: March 2010

AbstractSorption-desorption kinetics play a major role in transport and bioavailability of pollutants in soils. Contaminant concentration is a potentially important factor controlling kinetics. A previous paper dealt with the effect of solute concentration on fractional uptake rates of phenanthrene and pyrene from a finite aqueous source. In this study we determined the effect of initial phenanthrene sorbed concentration (q0) on the fractional mass desorption rates from each of six soils to a zero-concentration solution, approximated by including a polymer adsorbent (Tenax™) as a third-phase sink. The soils were preequilibrated with phenanthrene for 180 d. Consistent with theory, the fractional desorption rates determined by empirical curve fitting increased with q0 provided the isotherm was nonlinear. After 500 to 600 d of desorption at the steepest possible concentration gradient, all soils retained a highly resistant fraction, which ranged from 4 to 31% of q0, except for one soil at a high q0. The highly resistant fraction decreased with increasing q0 for nonlinear isotherm cases, but increased with q0 for linear or nearly linear isotherm cases. Application of a nonlinear diffusion model, the dual-mode diffusion model (DMDM), to the nonresistant fraction gave reasonably good fits. The DMDM attributes the increase with concentration of the apparent diffusivity to a decrease in the proportion of sorbate occupying immobile sites (holes) in soil organic matter. The concentration-dependent term in the expression for the apparent diffusivity correlated with either of two indices that reflect the linearity of the sorption isotherm. Bunker C oil present in one soil acted as a partition domain. The findings of this study are consistent with heterogeneous models of soil organic matter, and indicate that concentration effects should be taken into account whenever desorption rate is important.
Investigation of an onsite wastewater treatment system in sandy soil: Site characterization and fate of anionic and nonionic surfactants
Authors: Nielsen Allen M. , Decarvalho Alvaro J. , McAvoy Drew C. , Kravetz Lou , Cano Manuel L. , Anderson Damann L. 
Published: March 2010

AbstractThis study reports on the fate of linear alkylbenzene sulfonate (LAS), alcohol ethoxylate (AE), and alcohol ether sulfate (AES) surfactants in a home septic system near Jacksonville (FL, USA) that has been used since 1976. The drainfield at this site resides in fine sand (&lt;6% silt and clay) with an unsaturated zone that ranges from 0 to 1.3 m. During the wettest times of the year, it is likely that effluent from the septic system passes directly into the groundwater without exposure to an unsaturated zone of soil. Groundwater was collected during two sampling events, representing seasonal high and low groundwater table levels, and analyzed for the surfactants LAS, AES, and AE. During the wet season, the unsaturated zone was approximately 0.01 m beneath the drainfield. During the dry season, the unsaturated zone was about 0.4 m below the drainfield. Alcohol ethoxylate was not detected in any groundwater samples during either sampling. Alcohol ether sulfate was not found in the dry season sampling, but traces of AES had migrated downgradient about 4.7 m horizontally and 1.8 m vertically in the wet season. Linear alkylbenzene sulfonate was detected in some dry season samples and had moved downgradient some 11.7 m horizontally and 3.7 m vertically in the wet season. These observations demonstrate that these surfactants were removed to a great extent; otherwise, they would have traveled more than 260 m downgradient, which is the calculated distance that a conservative tracer like bromide would have moved downgradient over the life of the system. The most likely removal mechanisms for these surfactants were biodegradation and sorption. Therefore, this study indicates that LAS, AE, and AES are readily removed from groundwater in soils below septic system drainfields even in situations with minimal unsaturated soil zones.