bluuebunny/crossref_metadata_2025 huggingface dataset:
Toxicity of metal-contaminated sediments from keswick Reservoir, California, USA
Authors: Finlayson Brian , Fujimura Robert , Huang Zhang-Zhi
Published: March 2010

Keswick Reservoir, California, USA, receives metal-laden acid-mine drainage (AMD) from the abandoned Iron Mountain Mine. Mixing of the AMD with reservoir water causes precipitation and deposition of metal-rich sludge in the reservoir. Hydroelectric generation activities can scour the sediments and mobilize trace metals cadmium, copper, and zinc into the water column, thus creating potentially toxic conditions to fish and aquatic invertebrates. Sediment samples collected from Keswick Reservoir in 1993 and 1994 were analyzed for acid-volatile sulfides and for simultaneously extractable metals (SEM), and whole sediments and sediment elutriates were tested for toxicity to rainbow trout (Oncorhynchus mykiss), amphipods (Hyalella azteca), and cladocerans (Ceriodaphnia dubia). Acid-volatile sulfide concentrations in the sediments were low (<10 μmol/g H2S), indicating that dissolved metals in the sediment pore water were not limited by sulfide. The SEM concentrations were generally high (up to 11 μg/g Cd, 4,800 μg/g Cu, and 1,600 μg/g Zn, dry weight) in the sediments. Whole sediments and 20% w/w sediment elutriates from 16 sites were tested for toxicity. Low survival (as low as 0%) in whole sediments was generally associated with copper and zinc, and to a lesser extent cadmium, concentrations that exceeded probable effect level values for freshwater sediments; survival also may have been influenced by low pH and alkalinity conditions. Low survival (as low as 0%) in sediment elutriates was also generally associated with higher concentrations of dissolved zinc. Further study is required to formulate sediment cleanup levels that are protective offish and wildlife. Source control in the Iron Mountain Mine drainage will eventually significantly lessen the production of sediments.
Effects of physical (hypoxia, hyperoxia) and chemical (potassium dichromate, fenitrothion) stress on antioxidant enzyme activities inChironomus ripariusmg. (diptera, chironomidae) larvae: Potential biomarkers
Authors: Choi Jinhee , Roche Hélène , Caquet Thierry
Published: March 2010

Effects of physical (hypoxia, hyperoxia) and chemical (potassium dichromate, fenitrothion) stress on antioxidant enzyme activities and hemoglobin content in Chironomus riparius Mg. (Diptera, Chironomidae) larvae were evaluated under laboratory conditions in order to identify pertinent biomarkers of stress. Hypoxia and hyperoxia caused an increase in Cu,Zn-superoxide dismutase (SOD) and Mn-SOD activities and a simultaneous decrease in total peroxidase (Px) and glutathione peroxidase (GSH-Px) activities. A parallel increase in hemoglobin concentration in the hemolymph was observed. The exposure to sublethal concentrations of both potassium dichromate and fenitrothion led to an increase in Cu,Zn-SOD and Mn-SOD activities and to a decrease in GSH-Px activity. Activation of catalase (CAT) was observed in the larvae exposed to high fenitrothion concentration (20μg/L). The response of SODs was rapid and sensitive to low chemical concentrations, but changes in CAT, Px, and GSH-Px were more specific and less sensitive.
Behavior of aliphatic alcohol polyethoxylates and their metabolites under standardized aerobic biodegradation conditions
Authors: Marcomini Antonio , Zanette Mauro , Pojana Giulio , Suter Marc J.-F.
Published: March 2010

Aerobic biodegradation of aliphatic alcohol polyethoxylates (AEs) was tested under screening test conditions (Organization for Economic Cooperation and Development [OECD] 301E protocol) using recently developed analytic methodologies for the specific determination of AEs and their neutral (polyethylene glycols [PEGs]) and carboxylic (carboxylated PEGs and AEs) aerobic metabolites. Biodegradation screening tests were performed under the same conditions on three typical, commercial AE blends and an individual, linear AE ethoxymer. The linear and monobranched AEs underwent a fast primary biodegradation, whereas the multibranched AEs underwent a slower biodegradation. Based on the formation and oligomeric distribution of PEGs and the lack of detection of other biointermediates before the formation of PEGs, the central cleavage of the AE molecule appeared to be the mechanism for primary biodegradation of the linear and monobranched AEs in the tested commercial blends. As a result, the shorter AE ethoxymers biodegraded faster than the longer ones. No PEGs were detected during biodegradation of the multibranched AEs. In addition, PEGs biodegraded more slowly than the parent AEs and were removed by hydrolysis, thus leading to shorter PEG oligomers, and by oxidative hydrolysis, thus forming carboxylated PEGs.
Polychlorinated biphenyls pattern analysis: Potential nondestructive biomarker in vertebrates for exposure to cytochrome P450-inducing organochlorines
Authors: van den Brink Nico W , de Ruiter-Dijkman Elze M , Broekhuizen Sim , Reijnders Peter J H , Bosveld Albertus T C
Published: March 2010

Biomarkers are valuable instruments to assess the risk from exposure of organisms to organochlorines. Ingeneral, however, these biomarkers are either destructive to the animal of interest or extremely difficult to obtain otherwise. In this paper, we present a nondestructive biomarker for exposure to cytochrome P450-inducing organochlorines. This marker is based on a pattern analysis of metabolizable and nonmetabolizable polychlorinated biphenyl (PCB) congeners, which occur in several kinds of tissues (and even blood) that can be obtained without serious effects on the organism involved. The fraction of metabolizable PCB congeners is negatively correlated with exposure to PCBs, which are known to induce specific P450 isoenzymes. This relation can be modeled by a logistic curve, which can be used to define critical levels of exposure. In addition, this method creates an opportunity to analyze biomarker responses in archived tissues stored at standard freezing temperatures (−20°C), at which responses to established biomarkers deteriorate. Furthermore, this method facilitates attribution of the enzyme induction to certain classes of compounds.
Quantifying solar spectral irradiance in aquatic habitats for the assessment of photoenhanced toxicity
Authors: Barron Mace G , Little Edward E , Calfee Robin , Diamond Steven
Published: March 2010

The spectra and intensity of solar radiation (solar spectral irradiance [SSI]) was quantified in selected aquatic habitats in the vicinity of an oil field on the California coast. Solar spectral irradiance measurements consisted of spectral scans (280–700 nm) and radiometric measurements of ultraviolet (UV): UVB (280–320 nm) and UVA (320–400 nm). Solar spectral irradiance measurements were taken at the surface and at various depths in two marsh ponds, a shallow wetland, an estuary lagoon, and the intertidal area of a high-energy sandy beach. Daily fluctuation in SSI showed a general parabolic relationship with time; maximum structure–activity relationship (SAR) was observed at approximate solar noon. Solar spectral irradiance measurements taken at 10-cm depth at approximate solar noon in multiple aquatic habitats exhibited only a twofold variation in visible light and UVA and a 4.5-fold variation in UVB. Visible light ranged from 11,000 to 19,000 μW/cm2, UVA ranged from 460 to 1,100 μW/cm2, and UVB ranged from 8.4 to 38 μW/cm2. In each habitat, the attenuation of light intensity with increasing water depth was differentially affected over specific wavelengths of SSI. The study results allowed the development of environmentally realistic light regimes necessary for photoenhanced toxicity studies.
Fathead minnow vitellogenin: Complementary DNA sequence and messenger RNA and protein expression after 17β-estradiol treatment
Authors: Korte Joseph J , Kahl Michael D , Jensen Kathleen M , Pasha Mumtaz S , Parks Louise G , LeBlanc Gerald A , Ankley Gerald T
Published: March 2010

Induction of vitellogenin (VTG) in oviparous animals has been proposed as a sensitive indicator of environmental contaminants that activate the estrogen receptor. In the present study, a sensitive ribonuclease protection assay (RPA) for VTG messenger RNA (mRNA) was developed for the fathead minnow (Pimephales promelas), a species proposed for routine endocrine-disrupting chemical (EDC) screening. The utility of this method was compared with an enzyme-linked immunosorbent assay (ELISA) specific for fathead minnow VTG protein. Assessment of the two methods included kinetic characterization of the plasma VTG protein and hepatic VTG mRNA levels in male fathead minnows following intraperitoneal injections of 17β-estradiol (E2) at two dose levels (0.5, 5.0 mg/kg). Initial plasma E2 concentrations were elevated in a dose-dependent manner but returned to normal levels within 2 d. Liver VTG mRNA was detected within 4 h, reached a maximum around 48 h, and returned to normal levels in about 6 d. Plasma VTG protein was detectable within 16 h of treatment, reached maximum levels at about 72 h, and remained near these maximum levels for at least 18 d. While the RPA was about 1,000 times more sensitive than the ELISA, the ELISA appears superior for routine screening tests. The ELISA method is relatively simple to perform and, because males lack a clearance mechanism for VTG, the protein remains at relatively high concentrations in the plasma for an extended period of time. As part of the development of the RPA, the complementary DNA (cDNA) sequence for fathead minnow VTG was determined and the deduced amino acid sequence compared with VTG sequences for other fish species.
Estimation of exposure criteria values for biliary polycyclic aromatic hydrocarbon metabolite concentrations in white suckers (Catostomus commersoni)
Authors: Cormier Susan M , Lin Edith LC , Fulk Florence , Subramanian Bhagya
Published: March 2010

A methodology was developed for deriving quantitative exposure criteria useful for comparing a site or a watershed to a reference condition and for defining the occurrence of extreme exposures. The prototype method used indicators of exposures to oil contamination and combustion by-products, naphthalene (NAPH)-type and benzo[a]pyrene (BaP)-type biliary metabolites from white suckers (Catostomus commersoni). The fish were collected from first- to third-order streams in the Regional Environmental Monitoring Assessment Program (REMAP) study of the Eastern Corn Belt Plains ecoregion at randomly selected sites and from third- or higher-order streams in conjunction with the Ohio Environmental Protection Agency (OEPA) Biomonitoring Program, which sampled sites of concern and reference sites selected by ecologists. The polycyclic aromatic hydrocarbon metabolites were measured using fixed-wavelength fluorescence with excitation/emission pairs at 290/335 nm for NAPH-type and 380/430 nm for BaP-type metabolites. Exposure criteria values were selected for each type of metabolite for both the REMAP study and the OEPA reference sites following the recommendations of the International Federation of Clinical Chemistry. Exposure criteria derived for each metabolite were not significantly different for REMAP and OEPA reference sites. More than one half of the OEPA nonreference sites were found to be contaminated, exceeding criteria values for both types of metabolites. This method for finding meaningful exposure criteria can be used to develop criteria of exposure to other contaminants for other wildlife and other ecosystems.
A test of watershed classification systems for ecological risk assessment
Authors: Detenbeck Naomi E , Batterman Sharon L , Brady Valerie J , Brazner John C , Snarski Virginia M , Taylor Debra L , Thompson Jo A , Arthur John W
Published: March 2010

To facilitate extrapolation among watersheds, ecological risk assessments should be based on a model of underlying factors influencing watershed response, particularly vulnerability. We propose a conceptual model of landscape vulnerability to serve as a basis for watershed classification systems to predict resistance and resilience of aquatic ecosystems to hydrology-related stressors. Watershed area, storage capacity, channel slope, and soil permeability determine sensitivity of lotic systems to stressors associated with land-use activities that impact hydrologic regimes. Natural hydrologic disturbance regimes also influence the resilience of aquatic systems by selecting for life history strategies associated with rapid recolonization following disturbance. Variability in some of these physiographic driving factors can be partitioned by landscape classification schemes such as the U.S. Forest Service Ecological Unit Classification System, while others (watershed storage) may explain remaining variability within landscape units. We are conducting a comparative watershed study to examine simple and interactive effects of physiographic units, watershed storage (lakes + wetlands), and land-clearing activities in watersheds surrounding the western arm of Lake Superior. Initial results for second-order watersheds indicate significant watershed class effects on baseflow water quality, percent motile biraphid diatom species in periphyton communities, habitat quality, and fish community integrity. Future studies have been designed to examine cumulative effects downstream.
Ecological effects of experimental insecticide applications on invertebrates in sahelian temporary ponds
Authors: Lahr Joost , Diallo Alpha O , Gadji Baba , Diouf Papa S , Bedaux Jacques JM , Badji Aliou , Ndour Khalifa B , Andreasen Jude E , van Straalen Nico M
Published: March 2010

The ecological impact offour insecticides used to control desert locustswas investigated during experimental field trials in natural temporary ponds in a cultivated savannah area of Senegal, West Africa. The insecticide formulations, dose rates, and application techniques were similar to those used in operational desert locust control. Average initial concentrations of fenitrothion, diflubenzuron, deltamethrin, and bendiocarb in pond water were 80, 10.4, 0.45, and 24.0 μg/L, respectively. Diflubenzuron and deltamethrin virtually disappeared in 24 h. Pseudo–first-order half-lives were 34 h for fenitrothion and 17 d for bendiocarb. Fenitrothion and deltamethrin significantly reduced population densities of backswimmers of the genus Anisops (Hemiptera, No-tonectidae) and in addition caused an extensive kill of other species of insects. Both insecticide applications were also followed by reductions of zooplankton densities, especially Cladocera, and deltamethrin eradicated populations of fairy shrimp (Streptoce-phalus spp.: Branchiopoda, Anostraca). Diflubenzuron only affected crustaceans, i.e., cladocerans and fairy shrimp. The least harmful insecticide in the study was bendiocarb, which only reduced the density of cladocerans. Recovery proceeded at fixed rates, which were different for each taxon. Anisops spp. recovered from the treatments in 1 to 4 weeks, most likely through aerial migration. Cladocerans returned to normal densities in 3 to 6 weeks. Streptocephalus spp., however, whose resting eggs presumably need desiccation during the dry season to be able to hatch, did not reappear until the next rainy season, one year later. It is concluded that contamination of temporary ponds in the Sahel by insecticide drift from desert locust control operations with any of the four insecticides should be avoided.
Selected trace elements and organochlorines: Some findings in blood and eggs of nesting common eiders (Somateria mollissima) from Finland
Authors: Franson J Christian , Hollmen Tuula , Poppenga Robert H , Hario Martti , Kilpi Mikael , Smith Milton R
Published: March 2010

In 1997 and 1998, we collected blood samples from nesting adult female commoneiders (Somateria mollissima) at five locations in the Baltic Sea near coastal Finland and analyzed them for lead, selenium, mercury, and arsenic. Eggs were collected from three locations in 1997 for analysis of selenium, mercury, arsenic, and 17 organochlorines (OCs). Mean blood lead concentrations varied by location and year and ranged from 0.02 ppm (residues in blood on wet weight basis) to 0.12 ppm, although one bird had 14.2 ppm lead in its blood. Lead residues in the blood of eiders were positively correlated with the stage of incubation, and lead inhibited the activity of the enzyme delta-aminolevulinic acid dehydratase (ALAD) in the blood. Selenium concentrations in eider blood varied by location, with means of 1.26 to 2.86 ppm. Median residues of selenium and mercury in eider eggs were 0.55 and 0.10 ppm (residues in eggs on fresh weight basis), respectively, and concentrations of both selenium and mercury in eggs were correlated with those in blood. Median concentrations of p,p′-dichlorodiphenyldichloroethylene in eggs ranged from 13.1 to 29.6 ppb, but all other OCs were below detection limits. The residues of contaminants that we found in eggs were below concentrations generally considered to affect avian reproduction. The negative correlation of ALAD activity with blood lead concentrations is evidence of an adverse physiological effect of lead exposure in this population.
Heavy metal toxicity and genotoxicity in water and sewage determined by microbiological methods
Authors: Codina Juan C , Cazorla Francisco M , Pérez-García Alejandro , de Vicente Antonio
Published: March 2010

Acute toxicity and genotoxicity of cadmium, copper, chromium, mercury, nickel, and zinc dissolved in deionized water and in sewage were established by comparing the EC50 and EC20 values obtained by different microbial assays. For acute toxicity determination, The Netherlands Standard NEN6509 test, the spectrophotometric assays of respiratory inhibition using Saccharomyces cerevisiae and Pseudomonas fluorescens, and the Microtox® test were employed. To determine metal genotoxicity, the Salmonella typhimurium and Escherichia coli mutagenicity tests, the SOS-β-galactosidase genotoxicity test, and the Mutatox™ assay were used. The toxicity of the different assayed metals varied from the most toxic, mercury, to the least toxic, nickel and zinc. Two different rankings of toxicity and genotoxicity, very similar to each other, were established. The toxicity ranking was Hg > Cr > Cd ∼ Cu ∼ Zn > Ni, and the genotoxicity ranking was Hg > Cr > Cu ∼ Cd ∼ Ni > Zn. The association between the toxicity and genotoxicity of copper and chromium in the dissolved and suspended fractions of sewage was also determined. Copper was mainly associated with the suspended fractions and chromium with the dissolved fractions of sewage.
Estrogenicity of alkylphenolic compounds: A 3-D structure—activity evaluation of gene activation
Authors: Schmieder Patricia K , Aptula Aynur O , Routledge Edwin J , Sumpter John P , Mekenyan Ovanes G
Published: March 2010

A structure–activity relationship evaluation of alkylphenol activation of a human estrogen receptor (hER) reporter gene construct was done using the Common Reactivity Pattern approach. Energetically reasonable conformer distributions for selected steric and electronic chemical descriptors were presented and analyzed. Comparisons of descriptor distributions across active and nonactive chemicals allowed determination of a common reactivity pattern for hER activation. Chemicals capable of hER binding and gene transcription have high density of O–C{sp3}distances, from 6.2 to 6.5 Å; maximum distances between atoms in the molecule, ranging from 9.9 to 10.1 Å; and a population density on the lowest unoccupied molecular orbital for O-atoms from 0.09 to 0.12 AU. Alkylphenols that were nonactive in the recombinant yeast cell assay lacked these stereoelectronic requirements, presumably precluding receptor occupancy or necessary estrogen response element interaction. Derived reactivity patterns were successfully coded into decision trees used to screen additional alkylphenols for potential hER activation. Successful structure–activity relationship modeling and prediction of gene activation for 26 of 29 alkylphenols is an additional step in the elucidation of chemical steric and electronic three-dimensional parameters that predict which xenobiotics are likely to be estrogenic and demonstrates a valuable tool for screening and prioritization of chemicals for further testing.
Metabolic responses to acute toxicity of alkylphenols and alkylphenol polyethoxylates in Elliptio complanata measured by calorespirometry
Authors: Levine Catherine , Cheney Marcos A
Published: March 2010

Alkylphenol ethoxylates (APEs) are important contaminants of world water systems with effects on aquatic life. Metabolic responses to short-term acute toxicities of alkylphenol and alkylphenolethoxylates were investigated in the freshwater bivalve mollusk Elliptio complanata using isothermal batch microcalorimetry and respirometry. Metabolic heat rates were altered following short-time exposure of the gill tissue to these compounds over the concentration range of 10−6 to 10−3 M. There was a time and concentration dependence of the effects of alkylphenol and alkylphenolethoxylates on metabolic heat rates. In general, treatment with alkylphenols and alkylphenolethoxylates at concentrations ranging from 10−6 to 10−4 M caused stimulation of metabolic heat rates, possibly due to uncoupling of oxidative metabolism. Higher concentrations subsequently caused inhibition of metabolic activity and thus decreased heat rates. Rates of oxygen consumption by the gill tissue exposed to the surfactants, as a measure of effects on electron flux through mitochondria, showed a similar pattern of respiratory rate stimulation at low concentration and inhibition at higher concentration. Therefore, the batch calorespirometric method proved to be a useful technique to assess the toxicity of a group of surfactants on the control of energy flux in gills of a freshwater bivalve mollusk.
Effect of bisphenol a on the early life stage in Japanese medaka (Oryzias latipes)
Authors: Yokota Hirofumi , Tsuruda Yukinari , Maeda Masanobu , Oshima Yuji , Tadokoro Hiroshi , Nakazono Akinobu , Honjo Tsuneo , Kobayashi Kunio
Published: March 2010

Japanese medaka (Oryzias latipes) were exposed to bisphenol A (BPA) at the sublethal concentrations of 2.28, 13.0, 71.2, 355, and 1,820 μg/L (as mean measured concentrations) in the early life stage from fertilized eggs to 60-d posthatch. Except for the growth and sexual differentiation of the fish at 60-d posthatch, no effects were observed on hatching success and time to hatching in embryological stage and on mortality and abnormal behavior and appearance in hatched larvae. The growth of the fish was suppressed with increasing BPA concentrations, resulting in significant differences in both the total length and body weight of medaka at 1,820 μg/L compared with the controls. When observed for their external secondary sex characteristics, no males were identified in the 1,820-μg/L treatment. In addition, histological examination showed that 32% of fish in the 1,820-μg/L group had testis-ova composed of both testicular germ cells and oocytes. Consequently, the lowest effective concentration for the early life stage of medaka was between 355 and 1,820 μg/L. Since the environmental concentrations of BPA are usually three orders lower than the lowest effective concentration, BPA alone may not affect the early life stage of wild fish populations.
Transgenic strains of the nematode Caenorhabditis elegans as biomonitors of metal contamination
Authors: Cioci L K. , Qiu Ling , Freedman Jonathan H.
Published: March 2010

Transition metal contamination poses a serious environmental and human health threat. The bioavailability of transition metals in environmental samples can best be assessed with living organisms. A transgenic strain of the free-living soil nematode Caenorhabditis elegans has been engineered for monitoring the bioavailability of metals. A reporter transgene consisting of a fragment of the promoter from the C. elegans metallothionein-2 gene (mtl-2) that controls the transcription of a β-galactosidase reporter (lacZ) has been integrated into the genome of this organism. By using these transgenic C. elegans, the toxicological response to metals in samples can be quickly measured with a simple histochemical staining assay. The C. elegans that contain the mtl-2:lacZ transgene provide a more sensitive assay of exposure to cadmium, mercury, zinc, and nickel than 24-h LC50 assays or those using nematodes with heat-shock protein–based reporter transgenes. This study demonstrates that C. elegans that contain mtl-2:lacZ transgenes can function as sensitive toxicological indicators of metals.
Environmental risk limits for polychlorinated biphenyls in the Netherlands: Derivation with probabilistic food chain modeling
Authors: van Wezel Annemarie P , Traas Theo P , van der Weiden Martine E J , Crommentuijn Trudie H , Sijm Dick T. H M
Published: March 2010

Environmental risk limits (ERLs) for individual congeners of polychlorinated biphenyls (PCB 77, 105, 118, 126, 153, 156, 157, and 169) are derived. After lipid normalization, toxicity data for birds, mammals, and aquatic organisms were converted to equivalent concentrations in soil or sediment organic carbon (OC). Accumulation in the food chain was taken into account. Field-derived data on the environmental fate of PCBs, e.g., biomagnification factors and biota-to-sediment accumulation factors, were used in the calculations. The variability in these data was incorporated by using probabilistic techniques. Parameters that are difficult to measure for these hydrophobic compounds, such as the bioconcentration factor or the sediment/water partition coefficient, were avoided where possible. Probability distributions for various species were combined per congener when statistically appropriate; ERLs were based on the fifth percentile of these combined distributions. Congener patterns occurring in various sediments and invertebrates in The Netherlands were used for determining a mixture ERL for non- and mono-ortho PCBs. The PCB 118 was selected as a guiding congener. If the concentration of PCB 118 is less than 5 μg/kg OC, Dutch ecosystems are assumed to be protected for effects of the whole mixture of non- and mono-ortho-substituted PCBs. Concentrations associated with adverse effects in field studies were comparable to concentrations that would result if all congeners would be present at the ERL level.
Assessment of 2,4,6-trinitrotoluene toxicity in field soils by pollution-induced community tolerance, denaturing gradient gel electrophoresis, and seed germination assay
Authors: Siciliano Steven D , Gong Ping , Sunahara Geoffrey I , Greer Charles W
Published: March 2010

Determining the toxicity of contaminants to soil organisms under field conditions is hampered by site-specific and temporal factors that modulate contaminant availability. Assessing the pollution-induced community tolerance (PICT) of indigenous microbial communities integrates these complex environmental factors. The purpose of this study was to determine if the PICT response was proportional to 2,4,6-trinitrotoluene (TNT) concentrations in soil, if changes detected by PICT were also evident in soil microbial community composition, and if the PICT response correlated with phytotoxicity assays. Microorganisms extracted from TNT-contaminated field soils were mixed with a solution containing six different concentrations of TNT and inoculated into Biolog ECO plates. The utilization rate of substrates was determined over a 7-d period. Denaturing gradient gel electrophoretic analysis of a portion of the gene encoding 16S rDNA described the structure of the soil microbial community. Phytoindicators (Poa compressa and P. palustris L.) of TNT pollution were identified and used to assess TNT phytotoxicity in soil samples. The TNT (in Biolog wells) greatly inhibited microbial communities from locations with low in situ TNT exposure. The inhibition of microbial use of L-asparagine, L-phenylalanine, and D-glucosaminic acid by TNT (in Biolog wells) increased as TNT concentration in soil decreased. Locations differing in ECO-PICT response also differed in their microbial community composition and TNT phytotoxicity. Decreased phytotoxicity of field soils corresponded to decreases in PICT. The results from this study indicated that ECO-PICT is an effective assay to rapidly detect TNT exposure and toxicity in soil microbial communities.
Prediction of population-level response from mysid toxicity test data using population modeling techniques
Authors: Kuhn Anne , Munns Wayne R , Poucher Sherry , Champlin Denise , Lussier Suzanne
Published: March 2010

Acute and chronic bioassay statistics are used to evaluate the toxicity and risks of chemical stressors to the mysid shrimp Americamysis bahia (formerly Mysidopsis bahia). These include LC50 values from acute tests, chronic values (the geometric mean of the no-observed-effect concentration and the lowest-observed-effect concentration from 7-d and life-cycle tests), and U.S. Environmental Protection Agency water quality criterion continuous concentration (CCC). Because these statistics are generated from responses of individual organisms, the relationships of these statistics to significant effects at higher levels of ecological organization are unknown. This study was conducted to evaluate the quantitative relationships between toxicity test statistics and a concentration-based statistic derived from exposure–response models relating projected population growth rate to stressor concentration. This statistic, C*, describes the concentration above which mysid populations are projected to decline in abundance as determined using population modeling techniques. An analysis of responses of A. bahia to 10 metals, nine organic compounds, and ammonia surprisingly indicated the acute LC50 to be the best predictor of C*, followed by the chronic value from life-cycle tests, which predicted population-level response almost equally as well. The chronic value for the 7-d test was less predictive of population-level effects. The CCC was lower than C* for 94% of the compounds evaluated, indicating the criterion value to be protective of population-level effects for A. bahia, as intended.
Factors affecting the release of hydrophobic organic contaminants from natural sediments
Authors: Chen Wei , Kan Amy T , Fu Gongmin , Tomson Mason B
Published: March 2010

Numerous physical and chemical changes in aquatic systems can affect the sorption and desorption of organic contaminants. In this study, the effects of competitive sorption, caustic treatment, and temperature on the release of sorbed chlorinated hydrocarbons and naphthalene from natural sediments were studied. The experiments were specially designed so that the results would reflect the nature of the irreversible compartment. The effect of competitive sorption fell into two categories. The release of chlorinated benzenes and hexachlorobutadiene from the reversible fraction in Lake Charles, Louisiana, USA, sediment was increased with the competitive sorption of naphthalene, while the release of naphthalene and 1,4-dichlorobenzene from the irreversible compartments in Dickinson, Texas, USA, sediment was unaffected by the sorption of trans-cinnamic acid at 100 mg/L. Similarly, preliminary experiments showed that caustic treatment of sediments did not enhance the desorption from the irreversible fraction. Also, the enthalpy of sorption associated with the irreversible compartment was −21.60 ± 0.76 kJ/mol, indicating that sorption was via simple van der Waal's forces. Experimental results in this study support a previously proposed irreversible sorption mechanism in which irreversible sorption is attributed to the physical entrapment of organic molecules in sediment matrices after the hydrophobic partitioning.
Field study on desorption rates of polynuclear aromatic hydrocarbons from contaminated marine sediment
Authors: Zhang Yong , Wu Rudolf SS , Hong Hua-Sheng , Poon Ka-Fai , Lam Michael HW
Published: March 2010

The present study examines desorption kinetics of hydrophobic organic contaminants from sediment under conditions mimicking marine disposal. Trays of contaminated marine sediment were deployed in the subtidal zone of a pristine field site, and samples were taken at time intervals to study the desorption of acenaphthene, benzo[a]anthracene, benzo[b]fluoranthene, ben-zo[k]fluoranthene, benzo[a]pyrene, chrysene, fluoranthene, naphthalene, and phenanthrene over a period of 51 d. Results of the study indicated that 49.4 to 98.0% of the polycyclic aromatic hydrocarbons (PAHs) in the contaminated sediment were desorbed upon disposal in the coastal environment. The field desorption kinetics of these PAHs can be described by a two-compartment model. The measured slow desorption rate constants, k2, for acenaphthene, benzo[a]anthracene, benzo[b]fluoranthene, ben-zo[k]fluoranthene, benzo[a]pyrene, chrysene, fluoranthene, naphthalene, and phenanthrene were found to be 0.018, 0.061, 0.016, 0.028, 0.035, 0.021, 0.083, 0.031, and 0.080/d, respectively. Some of these data were in accordance with literature-reported values from laboratory desorption studies in which desorbed PAHs were directly extracted from the aqueous phase. However, they were at least an order of magnitude smaller than those obtained by conventional gas-stripping desorption techniques.
Survey of toxicity in ambient waters of the hudson/raritan estuary, USA: Importance of small-scale variations
Authors: Thursby Glen B , Stern Eric A , Scott K John , Heltshe James
Published: March 2010

This study was part of a characterization of the nature and severity of water-quality problems in the Hudson/Raritan Estuary in New York State and New Jersey, USA. The toxicity of ambient water was measured at 51 stations in the estuary by using standard tests with the sea urchin Arbacia punctulata and the marine red alga Champia parvula. Toxicity identification evaluations on samples from two stations suggested that cationic metals were the source of the observed toxicity. Overall results showed that toxicity could vary as much on the small scale, i.e., with depth and tide at a single site, as over several stations within a given subarea of the estuary. Thus, knowing about small-scale variations in toxicity is essential to understanding the significance of the variations from different areas or different sampling events.
Silver uptake by the green alga Chlamydomonas reinhardtii in relation to chemical speciation: Influence of chloride
Authors: Fortin Claude , Campbell Peter GC
Published: March 2010

Short-term (<1 h) silver uptake by the green alga Chlamydomonas reinhardtii was measured in the laboratory in defined inorganic media over a range of silver and chloride concentrations. For a low, fixed, free Ag+ concentration (e.g., 8 nM), silver uptake increases markedly (up to ∼4×) as a function of the chloride concentration (5 μM→4 mM Cl−); the free-ion model would have predicted a constant silver uptake rate. No evidence could be found for the passive diffusion of the neutral AgCl0 complex or for the facilitated uptake of the anionic AgCl−2 complex. The enhanced uptake observed in the presence of chloride is related to the very high silver uptake rates demonstrated by the test alga, which lead to diffusion limitation in the boundary layer surrounding the algal cell. In such a situation, metal accumulation is proportional to the total metal concentration (i.e., to the concentration gradient between the bulk solution and the algal surface). At higher silver concentrations (e.g., ≥ 10−7 M), diffusion in the phycosphere is no longer rate limiting, the chloride stimulation disappears, and silver uptake is sensitive to the free-ion concentration. However, such a high concentration of silver is not likely to be encountered in the environment, even in wastewater effluents.
Derivation and application of relative potency estimates based on in vitro bioassay results
Authors: Villeneuve Daniel L , Blankenship Alan L , Giesy John P
Published: March 2010

Relative potency (REP) estimates are widely used to characterize and compare the potency of a wide variety of samples analyzed using in vitro bioassays. Relative potency estimates are generally calculated as a simple ratio: the EC50 of a well-characterized standard divided by the EC50 of a sample. Such estimates are valid only when the dose-response curves for the sample and standard are parallel and exhibit the same maximum achievable response (efficacy). These conditions are often either violated or cannot be demonstrated. As a result, there is a need to calculate and present REPs in a manner that addresses the potential uncertainties caused by violation of the assumptions of parallelism and equal efficacy. Multiple point estimates, over the range of responses from EC20 to EC80, can be used to derive relative potency ranges (REP20–80 range). The width of a REP20–80 range is directly proportional to the degree of deviation from parallelism between sample and standard dose-response curves. Thus, REP20–80 ranges both test the assumption of parallelism and characterize the amount of uncertainty in an REP estimate resulting from deviation from parallelism. Although uncertainties due to unequal efficacy cannot be easily characterized mathematically, a systematic method for evaluating sample efficacy has been developed into a framework to guide the derivation and application of REP estimates based on in vitro bioassay results. Use of the systematic framework and REP20–80 ranges was illustrated using three sample data sets. It is hoped that the framework and discussion presented will facilitate the use of bioassay-derived REP estimates to characterize samples of both known and unknown composition without ignoring the assumptions underlying REP estimation.
Inhibition-based biosensors for the detection of environmental contaminants: Determination of 2, 4-dichlorophenoxyacetic acid
Authors: Botrè Claudio , Botrè Francesco , Mazzei Franco , Podestà Elisabetta
Published: March 2010

In this work data are reported on the possibility for detection of environmental contaminants endowed with toxic effects by specifically designed electrochemical biosensors. A new bienzymatic inhibition biosensor based on the combined catalytic activity of the enzymes alkaline phosphatase and glucose oxidase is proposed and discussed for the direct determination of 2, 4-dichloro-phenoxyacetic acid (2, 4-D), one of the most powerful and diffused defoliants, which also is endowed with estrogenic properties. A discussion on the different approaches followed to manage the experimental data obtained by enzymatic inhibition biosensors is also presented.
Mercury levels in tissues of otters from Ontario, Canada: Variation with age, sex, and location
Authors: Mierle Gregory , Addison Edward M , MacDonald Katherine S , Joachim Damien G
Published: March 2010

Concentrations of mercury in hair, brain, and liver tissues of river otter (Lutra canadensis) from several townships in Ontario, Canada, were determined. Levels of Hg in these tissues were highly intercorrelated but differed from tissue to tissue. The highest concentration was in hair, followed by liver and brain. The high correlation between Hg in hair and brain, as well as the ease and precision of Hg determinations on hair, demonstrate that Hg in hair holds considerable promise for monitoring the Hg in otters. Within the sampled otters, Hg varied with respect to age. The Hg concentrations increased over the first two to three years of age, remained stable over the next two to three years of age, and then declined in the remaining age-groups. Mean age of otters in townships with high-Hg concentrations was about half the mean age of otters in low-Hg townships. In areas where mercury levels are high, otters may have reduced survivorship because of Hg-induced stress on their health.
Assessing sediment contamination in estuaries
Authors: Chapman Peter M , Wang Feiyue
Published: March 2010

Historic and ongoing sediment contamination adversely affects estuaries, among the most productive marine ecosystems in the world. However, all estuaries are not the same, and estuarine sediments cannot be treated as either fresh or marine sediments or properly assessed without understanding both seasonal and spatial estuarine variability and processes, which are reviewed. Estuaries are physicochemically unique, primarily because of their variable salinity but also because of their strong gradients in other parameters, such as temperature, pH, dissolved oxygen, redox potential, and amount and composition of particles. Salinity (overlying and interstitial) varies spatially (laterally, vertically) and temporally and is the controlling factor for partitioning of contaminants between sediments and overlying or interstitial water. Salinity also controls the distribution and types of estuarine biota. Benthic infauna are affected by interstitial salinities that can be very different than overlying salinities, resulting in large-scale seasonal species shifts in salt wedge estuaries. There are fewer estuarine species than fresh or marine species (the paradox of brackish water). Chemical, toxicological, and community-level assessment techniques for estuarine sediment are reviewed and assessed, including chemistry (grain size effects, background enrichment, bioavailability, sediment quality values, interstitial water chemistry), biological surveys, and whole sediment toxicity testing (single-species tests, potential confounding factors, community level tests, laboratory-to-field comparisons). Based on this review, there is a clear need to tailor such assessment techniques specifically for estuarine environments. For instance, bioavailability models including equilibrium partitioning may have little applicability to estuarine sediments, appropriate reference comparisons are difficult in biological surveys, and there are too few full-gradient estuarine sediment toxicity tests available. Specific recommendations are made to address these and other issues.
Ecological condition of the estuaries of the Atlantic and Gulf coasts of the United States
Authors: Summers J Kevin
Published: March 2010

Monitoring the estuaries of the Atlantic and Gulf of Mexico coastlines of the United States from Cape Cod, Massachusetts, to Brownsville, Texas, was performed annually from 1990 through 1997 to assess ecological conditions on a regional basis for four biogeographic provinces. These province estimates-Virginian, Carolinian, West Indian, and Louisianian Provinces-are combined to provide an assessment of 87% of the estuarine area of the United States and 96% of the area of the Atlantic and Gulf coasts. Combining information over the six years of monitoring showed 34 ± 4% of the Atlantic and Gulf estuarine sediments displayed poorer than expected biological conditions, based on benthic and finfish community conditions, and 21 ± 4% of the area was characterized by low water clarity, the presence of marine debris/noxious odors, or elevated fish tissue contaminants.
Vapor pressures of six brominated diphenyl ether congeners
Authors: Tittlemier Sheryl A , Tomy Gregg T
Published: March 2010

Subcooled liquid vapor pressures (P oL of six polybrominateddiphenyl ether (PBDE) congeners containing three to seven bromine atoms were determined using the gas chromatograph retention time technique. Values ranged from 2.3 × 10−7 to 1.45 × 10−4 Pa at 25°C. An increase in the number of bromine atoms tended to decrease P oL according to the correlation logP oL = −0.692 (bromine number) −1.76 (R2 = 0.953, p < 0.001). In addition, the first such data for individual PBDE congeners demonstrates that P oL would vary four orders of magnitude over environmentally relevant temperatures.
Linear alkylbenzenes in muscle tissues of white croaker near a large ocean outfall in southern California, USA
Authors: Phillips Charles R , Venkatesan M Indira , Lin Timothy
Published: March 2010

Muscle tissues of a bottom-dwelling marine fish, white croaker (Genyonemus lineatus), collected near a large wastewater outfall in southern California, USA, were analyzed for long-chain linear alkylbenzenes (LABs). Total LABs (summed concentrations of C11 through C14 isomers) were highest (166–748 ng g−1 wet wt) in individuals collected in the immediate vicinity of the Orange County Sanitation District (OCSD; Fountain Valley, CA, USA) outfall diffuser, whereas relatively lower concentrations occurred in fish from mid-shelf and inshore locations at distances of 2.5 and 5 km, respectively, from the outfall. Fish tissue LAB concentrations were roughly proportional to sediment LAB concentrations at the respective collection sites. The extent of LAB degradation, as determined by ratios of internal to external C12 isomers, did not appear to relate to LAB concentrations or sampling location. Tissue DDT and PCB concentrations were not significantly correlated with LABs and, thus, did not appear to relate to recent exposures to sewage residues from the OCSD discharge. Measurements of LAB concentrations in fish tissues may be widely applicable as a monitoring tool for interpreting exposures to sewage discharges.
Reproductive and transgenerational effects of methylmercury or Aroclor 1268 onFundulus heteroclitus
Authors: Matta Mary Baker , Linse Jo , Cairncross Charles , Francendese Leo , Kocan Richard M
Published: March 2010

This research determined the potential for methylmercury or Aroclor 1268 to disrupt reproduction and sexual differentiation in Fundulus heteroclitus. The research determined whether fish that are exposed to mercury or Aroclor 1268 survive and successfully reproduce; whether offspring of exposed fish hatch, survive, produce eggs, and fertilize them; and whether the secondgeneration offspring of exposed fish hatch and survive. Fundulus heteroclitus were exposed to mercury or Aroclor 1268 via contaminated food. Endpoints evaluated included survival, growth, fecundity, fertilization success, hatch success, larval survival, sex ratios, and the prevalence of gonadal abnormalities. In general, polychlorinated biphenyls were highly bioavailable and accumulated well through feeding. The only statistically significant effect observed as a result of treatment with Aroclor 1268 was an increase in growth in the offspring of exposed fish. Mercury was accumulated in a dose-dependent fashion via food exposures. Exposure to mercury in food increased mortality in male F. heteroclitus, which possibly occurred as a result of behavioral alterations. Increased mortality was observed at body burdens of 0.2 to 0.47 μg/g. Offspring of F. heteroclitus fed mercury-contaminated food were less able to successfully reproduce, with reduced fertilization success observed at egg concentrations of 0.01 to 0.63 μg/g, which corresponds with parent whole-body concentrations of 1.1 to 1.2 μg/g. Offspring of exposed fish also had altered sex ratios, with treatment at moderate concentrations producing fewer females and treatment at the highest concentration producing more females than expected. Alterations in sex ratios were observed at concentrations of less than 0.01 μg/g in eggs or between 0.44 and 1.1 μg/g in parents. Offspring of mercury-exposed fish also had increased growth in moderate treatments, when egg concentrations were less than 0.02 μg/g, or when parent whole bodies contained 0.2 to 0.47 μg/g. In summary, exposure to mercury reduced male survival, reduced the ability of offspring to successfully reproduce, and altered sex ratios in offspring. Both direct effects on exposed fish and transgenerational effects were observed.