bluuebunny/crossref_metadata_2025 huggingface dataset:
Compositional and chiral profiles of weathered chlordane residues in soil
Authors: Eitzer Brian D , Mattina Maryjane Incorvia , Iannucci-Berger William
Published: March 2010

The fate of chlordane and other persistent organic pollutants in the environment is of international concern. The behavior of persistent organic pollutants under both abiotic and biotic conditions must be determined for the comprehensive elucidation of their cycling through the biosphere. Standard analytical methods such as gas chromatography with electron capture detection are adequate for studies of cycling under abiotic conditions. Since two of the main components of technical chlordane, cis-chlordane and trans-chlordane, are optically active, chiral gas chromatography can be used to study the impact of biotic influences on chlordane's fate. We report here the use of chiral gas chromatography interfaced with ion trap mass spectrometry as part of an analytically rigorous method for the simultaneous determination of the compositional and chiral profiles of weathered soil residues of technical chlordane. Using the method described, several patterns in the long-term weathering of technical chlordane in soil are observed.
A test system to evaluate the susceptibility of Oregon, USA, native stream invertebrates to triclopyr and carbaryl
Authors: Peterson Jennifer L , Jepson Paul C , Jenkins Jeffrey J
Published: March 2010

The susceptibility of six indigenous macroinvertebrate species representative of U.S. Pacific Northwest streams (Ameletus sp., Brachycentrus americanus, Calineuria californica, Cinygma sp., Lepidostoma unicolor, Psychoglypha sp. early and late instar) to formulated triclopyr ester (herbicide) and carbaryl (insecticide) was determined using laboratory bioassays. Acute toxicity was expressed as the lethal concentration to 50% (LC50) and 1% (LC1) of the test population based on a 96-h exposure duration. Carbaryl was found to be 1,000 times more toxic than triclopyr for all the organisms tested. The LC1 values (7.5, 28.8, 9.0, 3.0, 9.5, 14.8, 33.8 μg/L, respectively, for carbaryl and 1.8, 3.9, 4.0, 4.2, 29.0, 16.1 mg/L, respectively, for triclopyr) were used in the calculation of hazardous concentration to 5% of the stream macroinvertebrate community (HC5) based on the lower 95% confidence limit (HC5/95). The hazardous concentration (HC5/95) for triclopyr was 0.11 mg/L and for carbaryl ranged from 0.43 to 0.66 μg/L, respectively. Triclopyr and carbaryl symptomology were analyzed for two organisms, C. californica and Cinygma sp. Carbaryl symptomology included knockdown and moribund states with severity and time of appearance being a function of dose. In triclopyr poisoning, death occurred suddenly with little or no symptomology. Time to 50% mortality (LT50) values were consistently higher for C. californica than for Cinygma sp. exposed to both chemicals at similar concentrations.
Effect of varying pesticide exposure duration and concentration on the toxicity of carbaryl to two field-collected stream invertebrates, Calineuria californica (Plecoptera: Perlidae) and Cinygma sp. (Ephemeroptera: Heptageniidae)
Authors: Peterson Jennifer L , Jepson Paul C. , Jenkins Jeffrey J
Published: March 2010

The effect of exposure duration on the toxicity of a forest insecticide (carbaryl) was assessed under environmentally realistic exposure regimes against two stream invertebrates indigenous to the United States Pacific Northwest, Calineuria californica (Plecoptera: Perlidae) and Cinygma sp. (Ephemeroptera: Heptageniidae). Laboratory bioassays were conducted to evaluate the relationship between pulsed exposures of 15, 30, and 60 min and toxicity for a range of chemical concentrations (10.2–1,730 μg/L). For Cinygma sp., the 50% lethal concentration (LC50) values were calculated as 848 μg/L (15 min), 220 μg/L (30 min), and 165 μg/L (60 min). The C. californica consistently had lower mortality at a given concentration compared with Cinygma sp. Fifteen- and 30-min exposures did not elicit 50% mortality with C. californica, and it had a 60-min LC50 of 1,139 μg/L. Time to 50% mortality over 96 h after a 15-, 30-, or 60-min exposure, with the rest of the test period in freshwater (PLT50), was a function of exposure duration and concentration. Analysis of symptomology throughout the test period for C. californica gave evidence of recovery from the knockdown and moribund states, but this was not the case for Cinygma sp. The pulse duration resulting in 50% mortality was calculated as 43 min for Cinygma sp. exposed at 204 μg/L and 16 min at 408 μg/L. A three-dimensional probit plane model [Y = — 10.86 + 4.83(In C) + 3.0(In T)], where Y is probit mortality, C is concentration in μg/L and T is time in hours, was used to explain the interaction between concentration (μg/L) and duration of exposure (hours) for Cinygma sp.
Genetic diversity of the major histocompatibility complex of cotton rats (Sigmodon hispidus) inhabiting an oil refinery complex
Authors: Pfau Russell S , McBee Karen , Van Den Bussche Ronald A
Published: March 2010

We examined genetic diversity of an immune-response gene within the major histocompatibility complex in cotton rats (Sigmodon hispidus) inhabiting an oil refinery complex. Genetic diversity of MHC-DQA exon-2 was examined within and among contaminated and noncontaminated reference grids. The level of gene diversity within contaminated grids (0.748) was lower than within reference grids (0.818), but the difference was not statistically significant (p > 0.5). Analysis of molecular variance, pairwise FST values, and hierarchical clustering failed to reveal population genetic structure related to contamination. Results of this study indicate either that the level of contaminant-induced selection is insignificant at this major histocompatibility complex (MHC) locus or that gene flow from surrounding areas has obliterated the effects of selection.
A comparison of the effect of new and established insecticides on nontarget invertebrates of winter wheat fields
Authors: Moreby Stephen J , Southway Sue , Barker Alison , Holland John M
Published: March 2010

Six insecticides, a carbamate (pirimicarb), four pyrethroid/mixtures (tao-fluvalinate, zeta-cypermethrin, deltamethrin, and pirimcarb+deltamethrin), and an organophosphate (dimethoate), registered for use within cereals, were field-tested for toxicity to beneficial nontarget invertebrate groups important as food for farmland birds. Compared to the control and the other compounds, pirimicarb was the least toxic for most invertebrate groups examined. The pyrethroids and pyrethroid mixture significantly reduced numbers of many of the nontarget groups compared to the control and pirimicarb. Tao-fluvalinate was the least toxic pyrethroid tested when compared to the other compounds. Toxicity was further tested on larvae of graminivorous sawflies, an important chick-food group, using field-sprayed plants in laboratory and semifield trials. None of the pyrethroid and carbamate compounds and mixtures was as toxic as the organophosphate, but all were more toxic than the control. The semifield experiments provided a useful way of determining potential insecticide impact on this nontarget group where field populations are often too low for field trials to have statistically conclusive results.
Arsenic biotransformation by the brown macroalga Fucus serratus
Authors: Geiszinger Anita , Goessler Walter , Pedersen Søren N , Francesconi Kevin A
Published: March 2010

The brown alga Fucus serratus was maintained in aquaria with added arsenate (0, 20, 50, and 100 μg As/L, four individuals per treatment) for up to 19 weeks. Biotransformation of arsenic by Fucus was monitored by high-performance liquid chromatography/inductively coupled plasma mass spectrometry and liquid chromatography/electrospray mass spectrometry analysis of aqueous extracts of algal frond tips removed periodically throughout the experiment. Major arsenic species monitored were arsenate, arsenite, methylarsonate, dimethylarsinate, and the four arsenosugars 1 to 4 found naturally in Fucus. Algae accumulated arsenate readily and transformed it into several arsenic compounds depending on the exposure concentration. At 100 μg As/L, the major metabolite was arsenite with smaller quantities of methylarsonate and dimethylarsinate, but only traces of arsenosugars were formed. In contrast, the 20–μg-As/L group accumulated only small quantities of arsenite and methylarsonate, while dimethylarsinate and arsenosugars were major arsenic metabolites. At 50 μg As/L exposure, algae had significant quantities of all arsenic metabolites monitored. Arsenate was toxic to the algae at 100 μg As/L, but had no obvious detrimental effect at 20 μg As/L. The data are consistent with a process of arsenate detoxification by reduction and alkylation; at higher exposures, however, the alkylation processes become saturated, leading to an accumulation of arsenite and subsequent toxicity.
Polychlorinated biphenyl contamination and minisatellite DNA mutation rates of tree swallows
Authors: Stapleton Mary , Dunn Peter O , McCarty John , Secord Anne , Whittingham Linda A
Published: March 2010

The evidence that exposure to polychlorinated biphenyls (PCBs) leads to mutations is equivocal and controversial. Using multilocus DNA fingerprinting, we compared the mutation rate of tree swallows (Tachycineta bicolor) nesting at sites with high and low levels of contamination with PCBs. The upper Hudson River, USA, is highly contaminated with PCBs as a result of releases from two capacitor manufacturing plants in Hudson Falls and Fort Edward, New York, USA. Tree swallows nesting nearby have some of the highest known concentrations of PCBs in their tissues of any contemporary bird population (up to 114,000 ng PCB/g tissue). We found no difference in mutation rates between sites in New York with high PCB contamination and reference sites in Wisconsin, USA, and Ontario and Alberta, Canada, with known or presumably low levels of contamination. Thus, the mechanism behind altered reproductive behavior of tree swallows along the upper Hudson River is most likely physiological impairment, such as endocrine disruption, rather than mutation.
Effects of water hardness and dissolved organic material on bioavailability of selected organic chemicals
Authors: Akkanen Jarkko , Kukkonen Jussi V K
Published: March 2010

The influence of water hardness and dissolved organic matter (DOM) on bioavailability of organic chemicals to Daphnia magna was studied by using benzo[a]pyrene (BaP), pyrene, atrazine, and 3,3′,4,4′-tetrachlorobiphenyl (TCB) as model compounds. Two types of DOM were used, namely Lake Kontiolampi, Joeusuu, Finland water (KL) and Nordic reference fulvic acid (NoFA) dissolved in artificial freshwater. Binding of the four contaminants by KL, DOM decreased with increasing water hardness. Furthermore, increasing hardness reduced the binding of BaP and pyrene to NoFA. The binding of atrazine and TCB by NoFA was low and was not significantly affected by water hardness. In the DOM-free samples, the bioconcentration of the four contaminants in D. magna usually was not affected by water hardness. In the presence of DOM, the bioconcentration factors (BCFs) were lower (except for atrazine) than in the DOM-free controls. In the presence of both types of DOM, increasing water hardness resulted in higher BCFs for BaP. The bioconcentration of pyrene and TCB increased with increasing water hardness in the presence of KL DOM. In conclusion, the effects of DOM and water hardness on bioavailability of hydrophobic chemicals depend on the type of chemical and on the properties of DOM.
Bioassay of cadmium using a DNA microarray: Genome-wide expression patterns of Saccharomyces cerevisiae response to cadmium
Authors: Momose Yuko , Iwahashi Hitoshi
Published: March 2010

DNA microarray technology enables genome-wide detection of cell response at the transcriptional level. We are planning to make bioassay systems that can detect environmental chemicals to screen for potential bioreactive agents. To develop a DNA microarray for our purposes, the changes in gene expression underlying the yeast stress response to cadmium were analyzed by a microarray of total mRNA. Cadmium is a potent cell poison known to cause oxidative stress by changing intracellular glutathione levels. We report here that not only the glutathione synthesis gene (GSH1) but also almost all transcripts of the enzymes involved in the sulfur amino acid metabolism, especially MET14 and MET17, were greatly induced after exposure to cadmium. While several common stress-responsive genes, such as HSP26, GRE1, HSP12, and DDR48, were up-regulated more than almost fourfold by cadmium, there were also 42 other genes up-regulated more than fourfold. Based on these results, we concluded that DNA microarrays are very useful instruments for creating new bioassay systems and finding genetic promoters of stress indicators.
Disposition and depuration of lindane (γ-HCH) and polychlorinated biphenyl-110 (2,3,3′,4′,6-pentachlorobiphenyl) in cod (Gadus morhua) and bullrout (Myoxocephalus scorpius) after single oral exposures
Authors: Ruus Anders , Skaare Janneche Utne , Ingebrigtsen Kristian
Published: March 2010

The disposition and depuration of lindane (γ-hexachlorocyclohexane [HCH]) and polychlorinated biphenyl (PCB)-110 (2,3,3′,4′,6-pentachlorobiphenyl), orally administered to cod (Gadus morhua) and bullrout (Myoxocephalus scorpius), were investigated using whole-body autoradiography, liquid scintillation counting, and gas chromatography with electron-capture detection. Both γ-HCH and PCB-110 were distributed mainly to lipid-rich organs after absorption from the gastrointestinal tract of cod and bullrout. Compared to bullrout liver, the cod liver contained higher concentrations of both compounds, reflecting the distribution of fat in the two species. In both species, the depuration time for γ-HCH was shorter than for PCB-110. Both substances were excreted via bile and urine, largely as water-soluble metabolites. The water-soluble bile metabolites, together with PCB-110 metabolites associated to endogenous macromolecules, strongly indicate that this compound is metabolized in both species.
Biotic ligand model of the acute toxicity of metals. 1. Technical Basis
Authors: Di Toro Dominic M. , Allen Herbert E , Bergman Harold L , Meyer Joseph S , Paquin Paul R , Santore Robert C
Published: March 2010

The biotic ligand model (BLM) of acute metal toxicity to aquatic organisms is based on the idea that mortality occurs when the metal—biotic ligand complex reaches a critical concentration. For fish, the biotic ligand is either known or suspected to be the sodium or calcium channel proteins in the gill surface that regulate the ionic composition of the blood. For other organisms, it is hypothesized that a biotic ligand exists and that mortality can be modeled in a similar way. The biotic ligand interacts with the metal cations in solution. The amount of metal that binds is determined by a competition for metal ions between the biotic ligand and the other aqueous ligands, particularly dissolved organic matter (DOM), and the competition for the biotic ligand between the toxic metal ion and the other metal cations in solution, for example, calcium. The model is a generalization of the free ion activity model that relates toxicity to the concentration of the divalent metal cation. The difference is the presence of competitive binding at the biotic ligand, which models the protective effects of other metal cations, and the direct influence of pH. The model is implemented using the Windermere humic aqueous model (WHAM) model of metal—DOM complexation. It is applied to copper and silver using gill complexation constants reported by R. Playle and coworkers. Initial application is made to the fathead minnow data set reported by R. Erickson and a water effects ratio data set by J. Diamond. The use of the BLM for determining total maximum daily loadings (TMDLs) and for regional risk assessments is discussed within a probabilistic framework. At first glance, it appears that a large amount of data are required for a successful application. However, the use of lognormal probability distributions reduces the required data to a manageable amount.
Biotic ligand model of the acute toxicity of metals. 2. Application to acute copper toxicity in freshwater fish andDaphnia
Authors: Santore Robert C , Di Toro Dominic M , Paquin Paul R , Allen Herbert E , Meyer Joseph S
Published: March 2010

The biotic ligand model (BLM) was developed to explain and predict the effects of water chemistry on the acute toxicity of metals to aquatic organisms. The biotic ligand is defined as a specific receptor within an organism where metal complexation leads to acute toxicity. The BLM is designed to predict metal interactions at the biotic ligand within the context of aqueous metal speciation and competitive binding of protective cations such as calcium. Toxicity is defined as accumulation of metal at the biotic ligand at or above a critical threshold concentration. This modeling framework provides mechanistic explanations for the observed effects of aqueous ligands, such as natural organic matter, and water hardness on metal toxicity. In this paper, the development of a copper version of the BLM is described. The calibrated model is then used to calculate LC50 (the lethal concentration for 50% of test organisms) and is evaluated by comparison with published toxicity data sets for freshwater fish (fathead minnow, Pimephales promelas) and Daphnia.
Effect of sediment toxicity on anaerobic microbial metabolism
Authors: Togna Monica T , Kazumi Junko , Apitz Sabine , Kirtay Victoria , Young Lily Y
Published: March 2010

Mineralization of a readily biodegradable aromatic compound (benzoate) by intrinsic microorganisms in the anoxic sediment was used to quantify the inhibitory effect of heavily contaminated sediment from the Arthur Kill estuary (NY/NJ Harbor system, USA) on the anaerobic metabolism by naturally present bacterial populations. In anoxic microcosms, the effect of varying ratios of contaminated sediment: site water and contaminated sediment: noncontaminated sediment (Flax Pond, Stony Brook, NY, USA) were investigated. In all cases, increasing the ratio of Arthur Kill sediment in the microcosms showed an inhibitory effect on the rate of 14C-benzoate mineralization as measured by the evolution of 14CO2. This inhibitory effect could be alleviated through dilution of the sediment with noncontaminated sediment, resulting in some cases in mineralization rates that were greater by an order of magnitude. The toxicity of the sediment was confirmed by whole-sediment Microtox® bioassay. Analysis of the sediment revealed high (>200 mg/kg) levels of Pb, Cu, Zn, and Cr, suggesting that heavy metals may contribute to overall sediment toxicity.
Atrazine biodegradation to deisopropylatrazine and deethylatrazine in coastal sediments of different land uses
Authors: Aelion C. Marjorie , Mathur Priti P
Published: March 2010

Atrazine, a triazine herbicide widely used in the United States, contributes to surface-water and groundwater contamination, as can deisopropylatrazine (DIA) and deethylatrazine (DEA), two of its microbial degradation products. Production of DIA and DEA by native bacteria in aquatic sediments has not been investigated thoroughly. We assessed atrazine and production of DIA and DEA over time in coastal aquatic sediments associated with different land uses including creeks from an undeveloped preserve and a suburban development, a golf course drainage ditch, and a contaminated commercial harbor. Sediments were incubated in microcosms, spiked with U-14C-atrazine, extracted, and analyzed for 14C in a liquid scintillation counter. Atrazine, DIA, and DEA also were quantified by gas chromatography–mass spectrometry. The amount of 14C recovered varied at each site as a function of the sediment organic carbon content and decreased significantly over time. Both DEA and DIA were measured primarily in the aqueous phase. Transformation was more extensive to DIA than to DEA. The ratio of DIA to atrazine recovered from the undeveloped preserve was as high as 0.13. In contrast, the golf course had limited biotransformation, and had the greatest atrazine recoveries so atrazine, not DEA and DIA, may have a greater impact at this site.
2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents in tissue samples from three species in the Denver, Colorado, USA, metropolitan area
Authors: Coady Katherine K , Jones Paul D , Giesy John P
Published: March 2010

The Rocky Mountain Arsenal (RMA), a Superfund site near Denver, Colorado, USA, has a history of various industrial processes that may have led to the release of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and polychlorinated biphenyls (PCBs). The PCDDs, PCDFs, and non-ortho- and mono-ortho-substituted PCBs cause a common set of toxic effects that are mediated through the aryl hydrocarbon receptor (AhR). The total AhR-mediated activity of complex mixtures in biota samples from the RMA and surrounding reference areas was determined by both instrumental and bioanalytical techniques. Mean concentrations of bioassay-derived 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) equivalents (TCDD-EQ) in carp eggs, owl livers, and kestrel eggs ranged from 0 to 8.5, 17 to 130, and 2.4 to 18 pg/g, respectively. For most samples analyzed, concentrations of TCDD-EQ and instrumentally derived TCDD equivalents (TEQs) were not significantly different. In a few tissue samples, concentrations of TEQs and TCDD-EQs were not equivalent. This can indicate the presence of AhR-active compounds that were not identified or quantified by instrumental techniques or the existence of nonadditive interactions among congeners when samples are analyzed by the bioassay. Overall, mean concentrations of TCDD-EQs in extracts of carp and kestrel eggs were not significantly different between groups of samples collected on and off the RMA, whereas concentrations of TCDD-EQs in several owl livers collected on the RMA were significantly greater than concentrations in owl livers from off the RMA.
A method of estimating multicomponent nonaqueous-phase liquid mass in porous media using aqueous concentration ratios
Authors: Devlin John F , Barbaro Jeff R
Published: March 2010

A simple dissolution model based on Raoult's Law was used to derive a log-linear equation for the estimation of multicomponent nonaqueous-phase liquid (NAPL) mass in porous media. The analysis, referred to here as the ratio mass estimation (RME) method, requires aqueous concentration ratios for two components of the NAPL mixture as well as their pure phase liquid solubilities. Application of the equation using data from a previously reported column experiment, in which 1.22 g of a benzene/toluene NAPL were flushed with water, yielded an estimate of 1.2 g of NAPL. In addition, data from two in situ field column experiments of gasoline dissolution were examined. In those experiments, three ratio pairs, benzene/toluene, ethylbenzene/toluene, and ethylbenzene/benzene, were considered from each cell, and the initial NAPL masses were estimated to be between 39 and 42 kg NAPL, within 30% of the true NAPL masses of 54 kg in each cell. Finally, data from the flushing of a controlled release of chlorinated solvents (chloroform, trichloroethene, and tetrachloroethene) inside a sheet pile cell were examined, and the initial NAPL mass was estimated to within 15% of the true value. The RME analysis is based on several simplifying assumptions and should be used with caution. However, this work shows it to be potentially useful under conditions that might be encountered at sites. The analysis is simple and based on data that are often collected routinely.
Induction of morphological deformities in Chironomus tentans exposed to zinc- and lead-spiked sediments
Authors: Martinez Edward A , Moore Barry C , Schaumloffel John , Dasgupta Nairanjana
Published: March 2010

Laboratory experiments were used to assess morphological responses of Chironomus tentans larvae exposed to three levels of zinc and lead. Chironomus tentans egg masses were placed into triplicate control and metal-spiked aquaria containing the measured concentrations 1,442, 3,383, and 5,562 μg/g Pb dry weight and 1,723, 3,743, and 5,252 μg/g Zn dry weight. Larvae were collected at 10-d intervals after egg masses were placed in aquaria until final emergence. Larvae were screened formouthpart deformities and metal body burdens. Deformities increased with time of exposure in both Zn and Pb tanks. Deformity rates between the three Zn concentrations differed statistically, with low and medium Zn levels containing the highest overall deformity rates of 12%. Deformity rates for larvae held in the Pb aquaria were found to differ significantly. Larvae in the low-Pb tanks had a deformity rate of 9%. Larvae and water from both the Zn and Pb aquaria had increasing metal concentrations with increasing sediment metal concentration. Results demonstrate that Zn and Pb each induce chironomid mouthpart deformities at various concentrations. However, a clear dose-related response was not demonstrated. Our research provides more support for the potential use of chironomid deformities as a tool for the assessment of heavy metal pollution in aquatic systems.
Discrepancy between acute and chronic toxicity induced by imidacloprid and its metabolites in Apis mellifera
Authors: Suchail Séverine , Guez David , Belzunces Luc P
Published: March 2010

Imidaclopridi a systemic nitroguanidine insecticide that belongs to theneonicotinoid family. As an agonist of the acetylcholine receptor, it attacks the insect nervous system and is extremely effective against various sucking and mining pests. Oral acute and chronic toxicity of imidacloprid and its main metabolites (5-hydroxyimidacloprid, 4,5-dihydroxyimidacloprid, desnitroimidacloprid, 6-chloronicotinic acid, olefin, and urea derivative) were investigated in Apis mellifera. Acute intoxication by imidacloprid or its metabolites resulted in the rapid appearance of neurotoxicity symptoms, such as hyperresponsiveness, hyperactivity, and trembling and led to hyporesponsiveness and hypoactivity. For acute toxicity tests, bees were treated with doses of toxic compounds ranging from 1 to 1,000 ng/bee (10–10,000 μg/kg). Acute toxicity (LD50) values of imidacloprid were about 60 ng/bee (600 μg/kg) at 48 h and about 40 ng/bee (400 μg/kg) at 72 and 96 h. Out of the six imidacloprid metabolites tested, only two (5-hydroxyimidacloprid and olefin) exhibited a toxicity close to that of imidacloprid. Olefin LD50 values were lower than those of imidacloprid. The 5-hydroxyimidacloprid showed a lower toxicity than imidacloprid with a LD50 four to six times higher than that of imidacloprid. Urea also appeared as a compound of nonnegligible toxicity by eliciting close to 40% mortality at 1,000 ng/bee (10,000 μg/kg). However, no significant toxicity was observed with 4,5-dihydroxyimidacloprid, 6-chloronicotinic acid, and desnitroimidacloprid in the range of doses tested. To test chronic toxicity, worker bees were fed sucrose solutions containing 0.1, 1, and 10 μg/L of imidacloprid and its metabolites for 10 d. Fifty percent mortality was reached at approximately 8 d. Hence, considering that sucrose syrup was consumed at the mean rate of 12 μl/d and per bee, after an 8-d period the cumulated doses were approximately 0.01, 0.1, and 1 ng/bee (0.1, 1, and 10 μg/kg). Thus, all tested compounds were toxic at doses 30 to 3,000 (olefin), 60 to 6,000 (imidacloprid), 200 to 20,000 (5-OH-imidacloprid), and >1,000 to 100,000 (remaining metabolites) times lower than those required to produce the same effect in acute intoxication studies. For all products tested, bee mortality was induced only 72 h after the onset of intoxication.
Variation in cadmium uptake, feeding rate, and life-history effects in the gastropod Potamopyrgus antipodarum: Linking toxicant effects on individuals to the population level
Authors: Jensen Allan , Forbes Valery E , Parker E. Davis
Published: March 2010

A life-table response experiment was performed to investigate the effects of sediment-bound cadmium on individual life-history traits and feeding rates of four clones of Potamopyrgus antipodarum. Demographic effects were evaluated using a simple two-stage model to estimate population growth rate (λ). Decomposition analysis was performed to investigate the contributions of each of the affected life-history traits to the effects observed on λ, and elasticity analysis was applied to examine the relative sensitivity of λ to changes in each of the life-history traits. Interclonal differences in tolerance to sediment-bound cadmium were statistically significant but were within an order of magnitude. There were no consistent patterns among clones in terms of which individual life-history trait was most or least sensitive to cadmium exposure. The relative performance of clones did not rank consistently across the cadmium gradient and was dependent on which trait was measured. Although λ was most sensitive to changes in survival terms, the effects of cadmium on time to first reproduction and reproductive output were the major causes of reductions in λ. Large percent reductions in some of the individual life-history traits were attenuated at the population level, but very small effects on population growth rate were statistically significant.
Prediction of uptake of copper from solution by lettuce (Lactuca sativa Romance)
Authors: Cheng Tao , Allen Herbert E
Published: March 2010

We studied effects of free copper ion activity and total copper concentration on copper uptake by lettuce from nutrient solution and a model was developed. In ethylenediaminetetraacetic acid and dissolved organic matter treatments, when pH and free copper ion activity were the same, root copper concentration did not change with the total copper concentration. However, at fixed pH and total copper concentration, root copper concentration increased with, and was log-log linearly related to free copper ion activity. Copper uptake by plant roots is affected by free copper ion activity, pH, and the concentration of other competing ions such as Ca2+. Based on the free-ion activity model, we developed a model to predict copper concentrations in lettuce root and shoot. The parameters in this model are the binding constant of lettuce root surface site for copper times the site density, log(nKCu) = 11.29 ± 0.10; for protons, log(KH) = 6.80 ± 0.12; and for calcium, log(KCa) = 8.49 ± 0.30. Copper concentration in lettuce shoot was much lower than that of lettuce root. The translocation coefficient (k) is (2.36 ± 0.37) × 10−2.
Uptake of inorganic chemicals from soil by plant leaves: Regressions of field data
Authors: Efroymson Rebecca A , Sample Bradley E , Suter Glenn W
Published: March 2010

The estimation of chemical concentrations in wildlife foods, such as plant foliage, is often performed for risk assessments at contaminated sites. Regression models and uptake factors for use in estimating the uptake of inorganic elements from soil by above-ground plant tissues were derived in this study. These included models for arsenic, cadmium, copper, lead, mercury, nickel, selenium, and zinc. Models were developed using published data from soil contaminated in the field and were validated using measured concentrations from two contaminated sites. Single-variable regression models of log-transformed concentrations in plants versus log-transformed concentrations in soil are generally recommended over simple uptake factors for use in estimating plant uptake of inorganic contaminants in ecological risk assessments. Multiple regression models with soil concentration and pH as the variables are also recommended for estimating the uptake of four chemicals (cadmium, mercury, selenium, and zinc) by plants. Models for use in screening risk assessments, i.e., the upper 95% prediction limits on the regressions, are recommended to provide conservative estimates of uptake of inorganic chemicals by plants.
Does stress protein induction by copper modify natural toxicity in sponges?
Authors: Agell Gemma , Uriz María-J. , Cebrian Emma , Martí Ruth
Published: March 2010

Crambe crambe is a toxic Mediterranean sponge that inhabits the sublittoral rocky bottoms, including some contaminated habitats. We investigated whether contamination by copper induced stress proteins in C. crambe and whether such stress might alter the production of chemical defenses. The monoclonal antibody used cross-reacted with two heat shock proteins (HSP) of 54 and 72 kDa. Both proteins were induced to a greater or lesser extent by copper contamination. The HSP54 accumulated more than HSP72, which, in contrast, appeared to respond faster and be less persistent. In a field experiment, we found a higher accumulation of HSP54 in individuals naturally inhabiting a copper-contaminated site than in those transplanted to this site four months earlier. In contrast, HSP72 was significantly induced only in the individuals transplanted to the contaminated site. In the laboratory, both proteins were induced by copper at 30 μg/L but inhibited at 100 μg/L. The highest mean values of HSP54 and HSP72 corresponded to the sponges, which showed the lowest mean values of toxicity. Thus, toxicity and production of HSP displayed opposite trends, which seems to indicate a preferential investment in cell repair at the expense of toxic molecules under stress conditions.
Acute ecotoxicity of creosote-contaminated soils toEisenia fetida: A survival-based approach
Authors: Charrois Jeffrey W A , McGill William B , Froese Kenneth L
Published: March 2010

Quantification of risks to the ecosystem is necessary for cost-effective remediation strategies. Contaminant endpoints need to be established that consider the bioavailability of toxicants in soil. The challenge is to develop methods that assign risk to the bioavailable toxic contaminants, thereby protecting ecosystems, while balancing remediation costs. Our objective was to evaluate changes in bioavailability of creosote constituents in soils to earthworms. An acute ecotoxicological investigation of three weathered creosote-contaminated and two slurry-phase-biotreated soils was conducted using a 14-d earthworm (Eisenia fetida) survival bioassay. Soil characterization (physical and chemical) and contaminant concentration data (polycyclic aromatic hydrocarbons [PAH] and total dichloromethane extractable organics [DEO]) were also determined. The toxicity of the soils could not always be predicted based on chemical concentrations alone. Soils having a low PAH:DEO ratio had higher cumulative earthworm survival times as measured by earthworm-days. We propose that the DEO fraction may regulate toxicity by altering bioavailability of toxicants.
Laboratory analyses of the potential toxicity of sediment-associated polydimethylsiloxane to benthic macroinvertebrates
Authors: Henry Kevin S , Wieland Willemien H , Powell David E , Giesy John P
Published: March 2010

Polydimethylsiloxane (PDM)is widely used in a number of industrial processes and consumer products that result in down-the-drain disposal. The log p value for the PDMS used in the present study was 10, and the vapor pressure and water solubility values were below detection limits. These physicochemical characteristics and a measured degradation rate of 3% after six months in moist soils suggest that PDMS may accumulate in aquatic sediments. Sediment toxicity tests with the amphipod Hyalella azteca and with larvae of the midge Chironomus tentans were used to assess the potential for toxicity of PDMS-amended sediments to benthic invertebrates in short-term (10-d) and whole-life-cycle (28 d for H. azteca, 50–65 d for C. tentans) exposures. Endpoints for short-term tests included survival and growth, while life-cycle assays considered survival, growth, reproduction, and, for C. tentans only, emergence. Short-term and life-cycle exposures to concentrations of ≥1,000 mg PDMS/kg sediment (dry wt) indicated that PDMS will not reduce survival, growth, or reproduction in H. azteca or C. tentans.
Background zinc concentrations in soil affect the zinc sensitivity of soil microbial processes—a rationale for a metalloregion approach to risk assessments
Authors: McLaughlin Mike J , Smolders Erik
Published: March 2010

Soil microbial processes are particularly sensitive to Zn, but great difficulty exists in deriving soil standards based on laboratory toxicity tests. Zinc toxicity data for soil microbial processes were collated from the literature, and their variability with soil properties was assessed. Data were screened for quality and reliability, and analysis was based on the highest metal dose at which no adverse effect was found (HNOAED). The HNOAED values were expressed on a pore-water basis and were found to be positively related to background concentrations of Zn in soil, also expressed on a pore-water basis. This suggests that soil microorganisms acclimate to indigenous concentrations of Zn in soil pore water, and this acclimation affects the subsequent response to Zn added as a pollutant. Thus, regions having low background Zn concentrations in soil pore water will be much more sensitive to Zn pollution than others having high background concentrations. A method to account for effects of background Zn on assessments of Zn toxicity is suggested where metalloregions are defined having common sets of abiotic and biotic factors that affect the toxicity of Zn. This approach could markedly improve regional or continental risk assessments for metals in the environment.
Shrimp—a dynamic model of heavy-metal uptake in aquatic macrofauna
Authors: Simas Teresa Castro , Ribeiro Ana Paula , Ferreira João Gomes
Published: March 2010

A dynamic model for prediction of bioaccumulation in aquatic macrofauna is described. The model, entitled SHRIMP (Simulation of Heavy-metal Rate of Intake for Macrofaunal sPecies), consists of five coupled submodels, which simulate individual growth, population dynamics, metal transport in the abiotic part of the system, metal bioaccumulation at the organism level, and upscaling of individual contamination to the population scale. The sublethal effects of metal toxicity on individual and population levels are shown to act through the reduction of individual growth rates. The model was tested for cadmium and mercury using epibenthic crustacea from an estuarine system. Individual and population patterns of bioaccumulation were analyzed by comparing the simulated results of five different scenarios of dissolved metal concentrations. Model results suggest that the subtle effect of growth reduction due to metal toxicity is sufficient to cause a decrease on population numbers simply by affecting the growth of the mature females and males.
A rapid screening method for acid-volatile sulfide in sediments
Authors: Simpson Stuart L
Published: March 2010

A new, direct method for the determination of acid-volatile sulfide (AVS) in sediments is presented. The method utilizes the direct reaction of Clines reagent with small amounts of sediment followed by colorimetric determination of AVS and offers fast analysis times without the need for specialized glassware or equipment. A comparison between AVS measured by this method and that measured by a purge-and-trap AVS method shows a linear relationship (r = 0.986, p < 0.001), although the method underestimates the AVS concentration measured by the purge-and-trap method. Sample throughput by the direct AVS method is more than 10 times that of purge-and-trap methods. The applicability of the direct AVS method to the rapid screening of AVS concentrations in sediments and for evaluating sediment quality with respect to metal contamination is demonstrated.
Biotransformation of n-hexadecane by cell suspension cultures of Cinchona robusta and Dioscorea composita
Authors: Vega-Jarquin Carolina , Dendooven Luc , Magaña-Plaza Ignacio , Thalasso Frederic , Ramos-Valdivia Ana
Published: March 2010

This manuscript evaluates the phytotoxicity and biotransformation of n-hexadecane as well as peroxidase activity and cytochrome P450 concentration in microsomes for cell suspension cultures of Cinchona robusta and Dioscorea composita. Phytotoxicity was evaluated based on viability and growth. Cell cultures were exposed to a 2 and 4% (v/v) dose of n-hexadecane. The biotransformation of n-hexadecane was determined based on labeled recovery in polar, nonpolar, and cell residue fractions after cell culture extraction during exponential cell growth phase and stationary phase. Differences were observed in accumulation of label during cell growth phase and stationary phase for the cells of the two plants. Differences also were observed between phases for label in polar and nonpolar fractions. Thin-layer chromatography determined labeled intermediates and some were identified. The activity of peroxidase and concentration of cytochrome P450 was lower in C. robusta than in controls and greater in D. composita than in controls. In vitro biotransformation was not successful.
Stable carbon and nitrogen isotope analysis of TNT: Two-dimensional source identification
Authors: Coffin Richard B , Miyares Paul H , Kelley Cheryl A , Cifuentes Luis A , Reynolds C. Michael
Published: March 2010

Data from a combination of laboratory and fieldwork is presented to initiate testing of stable carbon and nitrogen isotope ratios to trace sources of TNT in contaminated soil and groundwater. Evaluation of these extraction methods resulted in 99.9 and 99.8% recovery of TNT with Soxhlet and solid-phase extraction (SPE), respectively. As a result of the high extraction efficiency, isotope fractionation did not occur, thus providing an accurate stable isotope value on TNT from laboratory and field samples. Subsequent experiments evaluated the stability of isotope signatures through incubations lasting up to four weeks with a 70% decline in the TNT concentration. During these experiments, no significant variation in stable carbon and nitrogen isotope ratios was measured. Five different sources of TNT, compared for stable carbon and nitrogen isotope ratios, showed a range of 4.2 and 15‰, respectively. This large range in the isotope ratios suggests excellent potential to trace sources in a complex environment. Finally, a site was surveyed for concentrations and isotope values of TNT extracted from groundwaters. Values from this site were substantially different relative to the variation measured on standards and in laboratory incubation experiments. The data set indicates good potential to use stable isotopes to determine TNT sources and fate in the environment.
Photodegradation of hydroxychlorothalonil in aqueous solutions
Authors: Armbrust Kevin L
Published: March 2010

Hydroxychlorothalonil is the principal degradation product of the fungicide chlorothalonil in soil, and it is routinely detected in leachate from golf course greens at concentrations as high as 2 ppm. However, it is not detected in receiving waters of shallow ponds. Irradiation with simulated sunlight degraded hydroxychlorothalonil in distilled-deionized water, phosphate buffer, and pond water with half-lives of approximately 30 min. Slower degradation was observed in solutions of NaCl and NaCN, suggesting photonucleophilic substitution reactions may be responsible for the degradation. Hydroxylated products resulting from the displacement of chlorine and cyano groups were detected within the first hour of irradiation but were subsequently degraded to small aliphatic acids (succinic, oxalic, and malonic acid) within 96 h. Simulations of aquatic dissipation of the chemical using the U.S. Environmental Protection Agency standard pond scenario in the exposure analysis modeling system indicate that the 30-min half-life measured in the laboratory would equate to a half-life of 2.6 d in a 2-m-deep pond and as much as 3.4 d in seawater. Although hydroxychlorothalonil is moderately stable and mobile in soil, these data suggest that, in surface water, it should be rapidly degraded by sunlight to small aliphatic acids on transport into aquatic systems.
Fate of atrazine and alachlor in redox-treated ferruginous smectite
Authors: Xu Jennifer C , Stucki Joseph W , Wu Jun , Kostka Joel E , Sims Gerald K
Published: March 2010

The oxidation state of structural iron (Fe) in clay minerals exerts a large influence on clay surface chemistry and may affect the adsorption and degradation of pesticides in the environment. This effect, however, has been little investigated. In the present study, herbicides atrazine and alachlor were reacted with ferruginous smectite (sample SWa-1) in its oxidized, reduced (either chemically or bacterially), and reduced–reoxidized states. In some experiments the herbicide was labeled with 14C. Gas chromatography/mass spectrometry (GC-MS) was also used to detect alachlor degradation products. Compared to oxidized clays, reduction by both chemical and microbial treatments decreased the concentration of both herbicides in the surrounding solution. Reoxidized clay exhibited behavior similar to the oxidized clay. Hydrolysis–dechlorination of atrazine occurred in the presence of chemically reduced SWa-1, and GC-MS analysis of alachlor revealed at least 14 degradation products after treatment with reduced clay and only two with the oxidized clay. Interaction of atrazine and alachlor with the clay may be through a H bond with the waters of hydration surrounding interlayer cations, the extent of which should increase with increasing acidity; but under reduced conditions, the validity of this model is unclear. Reduction of structural Fe may affect pH-dependent phenomena in two ways: The increased surface charge density increases the number of hydrated interlayer cations, thereby enhancing surface acidity, and increased electron density at basal surface oxygens increases their Brønsted basicity. Atrazine could, therefore, adsorb and/or degrade through either acid or alkaline hydrolysis pathways. Increased reduction potential of the reduced clay surfaces may also promote degradation.
Butyltin compounds in sediments from the commercial harbor of Alexandria City, Egypt
Authors: Barakat Assem O , Kim Moonkoo , Qian Yaorong , Wade Terry L
Published: March 2010

Tributyltin (TBT), dibutyltin (DBT), and monobutyltin (MBT) compounds were quantitatively determined in surface-sediment samples collected from 23 sites in the commercial harbor of Alexandria City, Egypt. Butyltin concentrations in sediments varied widely depending on the sample location, ranging from less than 0.1 to 186 ng g−1 of Sn for MBT, less than 0.1 to 379 ng g−1 of Sn for DBT, and 1 to 2,067 ng g−1 of Sn for TBT. Elevated TBT concentrations, ranging from 727 to 2,067 ng g−1 of Sn were observed in harbors, marinas, and near ship-repair facilities, indicating that the butyltin-containing, antifouling paints of boats and vessels are the major source of butyltin contamination. The TBT concentration decreased rapidly away from potential source areas of boat docking and repair facilities. The high relative concentrations of TBT in the sediments indicated that degradation processes in the sediments are minor, probably due to the anoxic sedimentary conditions at the sampling sites and/or relatively fresh input of TBT to these sites.