bluuebunny/crossref_metadata_2025 huggingface dataset:
Volatilization and sorption of dimethylsilanediol in soil
Authors: Lehmann Robert G. , Miller Jack R.
Published: March 2010

Our previous studies showed that dimethylsilanediol (DMD) was the main hydrolysis product of slicone (polydimethylsiloxane) polymer in soil. In the present study, volatilization of 14C-DMSD from soil (1 mg kg−1) was investigated in open tubes, with weekly remoistening. Losses of 14C from Londo sandy clay loam and Pipestone sand were about 3.6 and 7.7% wk−1, respectively, and were attributed mostly to volatilization. For select samples, DMSD was trapped and identified as the volatilized compound. From 12 soils of variable properties, losses ranged from 1.4 to 6.4% wk−1, with higher rates correlated with sandier textures. An estimated Kd of 0.1 L kg−1 in wet soil suggests potential mobility of DMSD, but increased bonding with soil drying means that mobility will be retarded under field conditions. Results suggest that volatilization will be a major route of loss of DMSD from soil.
Modified diffusion method for analysis of acid volatile sulfides and simultaneously extracted metals in freshwater sediment
Authors: Leonard Edward N. , Cotter Anne M. , Ankley Gerald T.
Published: March 2010

A modified procedure was developed for determining acid volatile sulfides (AVS) and simultaneously extracted metals (SEM) in freshwater sediments. A simple diffusion system employing relatively inexpensive glassware was compared to the more commonly utilized purge-and-trap system for generating AVS and SEM. Results obtained using the two different methods were generally comparable.
Hydrolysis and biodegradation of sulfonylurea herbicides in aqueous buffers and anaerobic water-sediment systems: Assessing fate pathways using molecular descriptors
Authors: Berger Bernhard M. , Lee Wolfe N.
Published: March 2010

The degradation of 12 sulfonylurea herbicides in buffers at different pH levels and in anaerobic sediments was investigated in laboratory studies. Reaction products, which are not commercially available, were synthesized in order to follow degradation kinetics. Different hydrolysis processes were shown to occur under acidic, neutral, and alkaline conditions. At 40°C, pseudo-first-order reaction rate constants between pH 4 and 10 covered two orders of magnitude. Activation energies of the acid-catalyzed hydrolysis were about 100 kJ/mol. Reaction rate-pH profiles were different for all compounds. In native sediments at neutral pH, microbial degradation was prevalent. At lower pH, chemical hydrolysis became more important. Pseudo-first-order dissipation rate constants between 12.50 × 10−2 d−1 and 0.19 × 10−2 d−1 were determined. Quantum-chemical molecular descriptors were calculated with MOPAC, and steric, electronic, and geometrical descriptors with Molecular Modeling Pro. Quantitative structure-reactivity relationships were found between bond orders, atomic charges, lowest unoccupied molecular orbitals, and pKa values on one hand and rate constants on the other. Disappearance rates in native sediments could be assessed with a multiple correlation considering calculated octanol water partition coefficients, parachors, and the atomic charges at the main reactive site of the molecules.
Uptake of hydrophobic xenobiotics by fish in water laden with sediments from the fraser river
Authors: Qiao Peiwen , Farrell Anthony P.
Published: March 2010

We examined the uptake of three hydrophobic chemicals, TCB (1,2,4-trichlorobenzene), PeCB (1,2,3,4,5-pentachlorobenzene), and HCBP (2,2′,4,4′,6,6′-hexachlorobiphenyl), by unfed juvenile rainbow trout (Oncorhynchus mykiss) in test aquaria containing sediments from the Fraser River. Our working hypothesis was that the low organic carbon content of the Fraser River sediments would increase the bioavailability of xenobiotics associated with these sediments. The test chemicals and sediments were introduced into aquaria 9 d before the fish were introduced. Measured concentrations of the chemicals in the bottom sediments, suspended sediments, and filtered (0.45 μm) water suggested that the test system had reached a quasiequilibrium state by day 9. Subsequently, a 6-d exposure of fish in the test aquaria resulted in a significant accumulation of the test chemicals in the fish tissues and significant reductions in the chemical concentrations of the bottom sediments, suspended sediments, and filtered water. Mass balance analysis suggests that the appearance of HCBP and PeCB in the fish after 6 d could not be accounted for solely by the amount of chemical dissolved in the water at the time when the fish were introduced. A large unaccounted-for fraction of TCB, possibly due to fish metabolism, precluded an accurate mass balance analysis for this chemical. Because chemical uptake in fish with the pharynx plugged (to eliminate the gut uptake route) was similar to that in control fish and because direct access to bottom sediments did not alter chemical uptake, we conclude that hydrophobic chemicals such as PeCB and HCBP associated with suspended sediments from the Fraser River can readily desorb and be taken up across the gill.
The influence of pH and media composition on the uptake of inorganic selenium by Chlamydomonas reinhardtii
Authors: Riedel Gerhardt F. , Sanders James G.
Published: March 2010

The uptake of inorganic selenium species, selenate and selenite, by the green alga Chlamydomonas reinhardtii Dang was examined as a function of pH over the range 5 to 9 and in media with varying concentrations of major ions and nutrients using 75Se as a radiotracer. Little difference was noted in the uptake of selenate as a function of pH, with the maximum uptake occurring at pH 8; however, selenite uptake increased substantially at the lower pH values. Selenate uptake was significantly decreased by higher sulfate concentrations and increased significantly by calcium, magnesium, and ammonium. Selenite uptake was significantly increased when the phosphate concentrations in the media were reduced. The results of these experiments demonstrate that varying water chemistry may significantly affect the uptake of inorganic selenium by phytoplankton and the subsequent transfer of the selenium to higher trophic levels.
Comparing differences in species sensitivity to toxicants: Phenotypic plasticity versus concentration-response relationships
Authors: Kammenga Jan E. , Riksen Joost A. G.
Published: March 2010

The comparison of species sensitivity to toxicants is classically derived from differences in the concentration-response relationships of a sensitive trait such as reproduction. We tested this general concept by conceiving the concentration-response relationship as a plastic response to a range of discrete environments. Using a demographic model based on life-cycle experiments for two nematode species (Plectus acuminatus and Heterocephalobus pauciannulatus) we related copper-induced plasticity in reproduction to changes in fitness, which was defined as the population growth rate. Daily reproduction (nt) in P. acuminatus was more sensitive to copper (EC20 = 48 μM) than in H. pauciannulatus (EC20 =138 μM). However, the relationship between plasticity in nt and fitness showed that for both species, fitness was reduced with 5%. These findings imply that P. acuminatus and H. pauciannulatus are equally susceptible to toxicant-induced changes in nt despite their differences in EC20 values for reproduction. It may be concluded that differences in susceptibility of species to toxicants are not only determined by the effect on sensitive traits but also by the relationship between plasticity in this trait and fitness.
Microbial ecology, toxicology and chemical fate of methyl isothiocyanate in riparian soils from the upper Sacramento river
Authors: Taylor George E. , Schaller Kastli B. , Geddes Jason D. , Gustin Mae S. , Lorson Gwen B. , Miller Glenn C.
Published: March 2010

On July 14, 1991, 72,000 L of the pesticide Metam (active ingredient, methyl isothiocyanate) was accidentally released into the Upper Sacramento River. We hypothesized that the spill affected streamside microbial communities and that the effects were persistent. To address this hypothesis, we sampled river soils a year later from sites above and below the spill as well as from an agricultural area and determined soil carbon dioxide efflux (as a measure of soil respiration) in response to methyl isothiocyanate in controlled-environment microcosms, resulting in estimates of the EC50 and soil degradation rates of methyl isothiocyanate. The soil respiration EC50s for the river soils ranged from 13.2 to 51.4 μg/g methyl isothiocyanate, whereas that of the agricultural soil was 72.2 μg/g. Thus, the soils from the Upper Sacramento River were more sensitive to the toxicologic effects of methyl isothiocyanate than was the agricultural soil. Soils from below the spill site also showed higher (factor two or more) EC50s than soils from reference locations above the spill site. The half-life of methyl isothiocyanate in soils ranged from 2.7 to 6.9 days and was longer by a factor of two in the river soils. These degradation rates are controlled by both biotic (microbial) and abiotic processes. The presence of a microbial community accelerated the degradation rate by a factor of two. The pattern of EC50 data demonstrates that changes in the microbial community in the river soils were persistent a full year after the spill and that the stress elicited responses that were indicative of physiologic accommodation or selection for resistance at the population, species, and/or community level.
Environmental effects of a discharge of drill cuttings contaminated with ester-based drilling muds in the north sea
Authors: Daan Rogier , Booij Kees , Mulder Maarten , Van Weerlee Evaline M.
Published: March 2010

A field-monitoring program has been carried out to assess the environmental effects associated with drill cutting discharges at a drilling location in the North Sea, after drilling with ester-based muds. The study included a baseline survey just before drilling started and three postdrilling surveys, 1, 4, and 11 months after termination of drilling. During these surveys, ester concentrations and macrofauna densities were determined at distances between 75 and 3,000 m from the well. For the first and second postdrilling surveys, ester concentrations ranged between 2 and 4,700 mg·kg−1 dry sediment. During the third survey, esters were detected up to 200 m, with concentrations between 1 and 250 mg·kg−1 dry sediment. Between 500 and 3,000 m, ester concentrations were below detection level. The half-life was estimated as 133 d. This value reflects the composite effects of biodegradation and sediment relocation. During the second postdrilling survey, a reduced abundance as well as a reduced species richness of the macrofauna was observed up to 200 m from the well. Also, the presence of Capitella capitata was an obvious sign of disturbed sediment conditions in this area. A few species showed abundance gradients over the whole sampling transect and occurred in reduced abundance up to 500 or 1,000 m compared to the 3,000-m reference station. The third postdrilling survey clearly revealed effects at 75 to 200 m from the well. At distances ≥500 m, persistent effects could no longer be demonstrated. Although the results of the present study show that effects had not completely disappeared after 1 year, there are signs of recovery of the macrobenthos, because a reasonable number of species had recolonized the area in the vicinity of the well site, particularly at 200 m, in fairly high numbers.
The influence of soil environmental variables on the degradation and volatility of methyl bromide in soil
Authors: Rice Patricia J. , Anderson Todd A. , Cink James H. , Coats Joel R.
Published: March 2010

Recent controversy over the potential role of methyl bromide (MeBr) in damaging the ozone layer has spurred interest in qualitatively increasing our understanding of the transformation and movement of this fumigant. In contrast to the extensive uses of this common agricultural fumigant, a paucity of data exits on the environmental fate of MeBr. Our research indicates that MeBr is rapidly volatilized from fumigated soil (within the first 24 h) and volatility significantly increases with temperature (35°C > 25°C > 15°C) and moisture (−3 kPa > −33 kPa > −300 kPa). Degradation of MeBr, measured by production of bromide ion (Br−), was also positively related to temperature and moisture. Undisturbed soil column studies indicated that MeBr rapidly volatilized (>50% of the MeBr flux occurred in 48 h) and did not leach into subsurface soil. Residual MeBr was degraded in the soil column, as evident by the high concentrations of Br− in the leachate water. These studies provide valuable information for assessing the fate of MeBr in soil, which should lead to more informed decisions for regulating its use.
Neutral red retention by lysosomes from earthworm (Lumbricus rubellus) coelomocytes: A simple biomarker of exposure to soil copper
Authors: Weeks Jason M. , Svendsen Claus
Published: March 2010

A simple subcellular histochemical staining technique employing the lysosomal probe neutral red has been developed for use with the epiendogeic earthworm Lumbricus rubellus Hoffmeister. Coelomocytes extracted from the coelomic cavity of earthworms into an isotonic earthworm Ringer solution were allowed to adhere to a microscope slide for 30 s before the application of a neutral red dye (80 mg·ml−1). This red dye was rapidly accumulated within the lysosomes. Observation of the loss of this dye from these lysosomes into the surrounding cytosol has enabled the quantification of the degree of lysosomal damage caused to earthworms with exposure to an increasing range of soil copper concentrations, in both laboratory and mesocosm studies. This simple in vitro biomarker has potential for the rapid assessment of the toxic effects to earthworms from soils contaminated with heavy metals and metalloids.
Pigmented macrophage aggregates: A toxic response in fish exposed to bleached-kraft mill effluent?
Authors: Couillard Catherine M. , Hodson Peter V.
Published: March 2010

An epidemiological study was conducted to evaluate whether the density of pigmented macrophage aggregates (PMAs) and the prevalences of preneoplastic and neoplastic lesions increased in fish captured downstream from a bleached-kraft pulp mill, causing induction of cytochrome P4501A enzymes (CYP1A). White suckers (Catostomus commersoni) sampled 10 and 95 km downstream from a bleached-kraft pulp mill in the St. Maurice River, Quebec, Canada, exhibited higher densities of PMAs relative to age in liver, spleen, and kidney than fish sampled 10 km upstream. White suckers were also sampled at three sites in the Gatineau River, Quebec, Canada, a reference river with a similar upstream/downstream ecological gradient but no pulp mill. In the Gatineau, density of PMAs was lower in the liver of fish sampled at the most downstream site, and there was no difference among sites in spleen and kidney. Higher growth rates have been documented at downstream sites of both rivers and thus cannot explain the increased density of PMAs observed at downstream sites of the St. Maurice River only. Density of PMAs did not differ between sexes or between fish with or without grossly visible parasites or granulomatous histological lesions. Although we cannot exclude the involvement of unknown infectious agents, density of PMAs appears to be a useful marker of bleached-kraft mill effluent (BKME) toxicity. Several known toxic effects of BKME could contribute to this response, including increased rates of lipid peroxidation associated with induced CYP1A and toxic hemolysis. Further field and laboratory studies are needed to evaluate whether the association between BKME exposure, induction of CYP1A, and increased density of PMA is consistent. Preneoplastic lesions were not observed in fish captured downstream of the pulp mill in the St. Maurice River, and only one case of biliary carcinoma was observed, at the most contaminated site.
Oxygen limitations and aging as explanations for the field persistence of naphthalene in coal tar-contaminated surface sediments
Authors: Madsen E.L. , Mann C.L. , Bilotta S.E.
Published: March 2010

Naphthalene has been transported approx. 400 m via groundwater flow from buried subsurface coal tar to an organic matter-rich seep area where the water emerges at the foot of a hill in a field study site. We have tested several hypotheses for explaining why naphthalene persists in seep sediments. In aerobic laboratory flask assays, conversion of 14C-naphthalene to 14CO2 occurred and was not stimulated by amendments with vitamins or inorganic nutrients. Thus, neither toxicity nor nutrient limitation were the cause of naphthalene persistence. At the site, in situ sediment oxygen concentrations were below detection. Oxygen-limited naphthalene biodegradation was demonstrated both by measuring no conversion of 14C-naphthalene to 14CO2 in samples of seep sediments prepared anaerobically and by measuring naphthalene loss from anaerobic nitrate-amended slurry-phase incubations of the sediment only after O2 was added. However, when H2O2 was added as an O2 source to site sediments in situ in a randomized block design, no discernible naphthalene loss occurred. The possibility that decreased bioavailability might contribute to naphthalene persistence was investigated by monitoring 14CO2 evolved by microorganisms added to γ-ray sterilized sediments that had been exposed under aseptic conditions to 14C-labeled naphthalene for periods ranging from 0 to 28 d. Resulting patterns in the extent and rate of naphthalene mineralization revealed an inverse relationship to the duration of contact with the sediment, but only when the mixed microbial inoculum had been enriched on aqueous-phase naphthalene. We conclude that oxygen limitation is the most probable cause for lack of naphthalene biodegradation at our field study site. However, diffusion or sorption reactions may also play a role.
Effects of substrate mineralogy on the biodegradability of fuel components
Authors: Apitz Sabine E. , Meyers-Schulte Kathleen J.
Published: March 2010

Experiments were carried out to determine the effects of mineralogy on the biodegradability of components of a whole fuel by a soil microbial consortium. Samples of quartz sand (Fischer Sea Sand) and illite clay (API 35) were spiked with marine diesel fuel, aged, slurried, and inoculated, and concentrations of fuel components were monitored over time. To help distinguish biotic from abiotic processes, identical samples were poisoned with mercuric chloride and were run in parallel. While there was chromatographic and biomarker evidence of n-alkane biodegradation in the sand samples, illite samples showed no evidence of biogenic loss of aliphatic components. Polycyclic aromatic hydrocarbons, on the other hand, were lost equivalently on both minerals and in both cases were lost to a much greater extent than were total petroleum hydrocarbons (TPHs). These results suggest that under our experimental conditions, illite inhibited the bioavailability of some TPH components to the soil microbial consortium.
Fate and disposition of diflubenzuron in rice fields
Authors: Mabury Scott A. , Crosby Donald G.
Published: March 2010

Laboratory and field investigations were undertaken to determine the fate, disposition, and persistence of the insecticide diflubenzuron in California rice culture. Water solubility was similar in distilled/deionized water (88.8 ± 4.0 μg/L) and rice field water (92.6 ± 3.5 μg/L), while the measured Henry's law constant was 2.34 ± 0.02 × 10−1 Pa.m3/mole. Diflubenzuron was rapidly photodegraded in field water primarily to the more stable chlorophenylurea and difluorobenzoic acid; field water photolysate was equally toxic to Daphnia magna as pure insecticide solutions. Applications to experimental rice field plots resulted in rapid dissipation of diflubenzuron (half-life 27.3 h), nonpersistent sediment residues, and significant partitioning into the surface microlayer.
Reductive dechlorination of chlorobenzenes in surfactant-amended sediment slurries
Authors: Van Hoof Patricia L. , Jafvert Chad T.
Published: March 2010

Microbial anaerobic dechlorination of hexachlorobenzene (HCB) was examined in sediment slurries amended with two classes of nonionic surfactant, polyoxyethylene (POE) sorbitan fatty acid esters (Tweens) and POE alcohols (Brijs). The rationale for surfactant addition was to increase the bioavailability of highly sorbed organic pollutants to degrading microorganisms by enhancing their solubility. The solubility of HCB was initially enhanced via micellar partitioning; however, primary degradation of most surfactants occurred within 10 d. Dechlorination activity was significantly reduced at POE alcohol concentrations above the critical micelle concentration (cmc), with or without the occurrence of surfactant degradation. Tween 80 decreased HCB dechlorination at concentrations significantly above the cmc (1,500–5,000 mg/L). At concentrations closer to the cmc (300–1,200 mg/L), Tween 80 increased dechlorination rate constants four- to fivefold in acclimated slurries. Additions of Tween 80 at or below the cmc (3, 30, 300, and 911 mg/L) stimulated dechlorination activity in unacclimated slurries that exhibited very little activity in unamended controls. An average of 89% of HCB was dechlorinated after 90 d, compared to 20% in unamended sediments. No effect was observed for POE alcohols at these sub-cmc levels. The lack of a stimulated response for the POE alcohols suggests that Tween 80 may not be acting simply as a source of carbon or energy.
Measuring bioavailable copper using anodic stripping voltammetry
Authors: Deaver Emily , Rodgers John H.
Published: March 2010

Since speciation can affect bioavailability and toxicity of copper in aquatic systems, accurate predictions of effects of bioavailable forms require detection and/or measurement of these forms. To develop an approach for measurement of bioavailable copper, a copper sulfate solution (CuSO4·3Cu(OH)2·H2O) was used in 10-d aqueous and sediment toxicity tests with Hyalella azteca Saussure. These tests encompassed ranges of pH (6.5 to 8.1), alkalinity (10 to 70 mg/L as CaCO3), hardness (10 to 70 mg/L as CaCO3), and conductivity (30 to 300 μmho/cm). Changes in copper speciation were measured using atomic absorption spectroscopy (AA) for dissolved copper and differential pulse anodic stripping voltammetry (DPASV) for labile copper, and concentrations were evaluated relative to amphipod survival. Ten-day LC50s based on AA-measured aqueous copper concentrations ranged from 42 to 142 μg Cu/L, and LC50s based on DPASV-measured copper concentrations ranged from 17.4 to 24.8 μg Cu/L. In 10-d tests using copper-amended sediments with diverse characteristics and AA-measured copper concentrations spanning an order of magnitude, total copper concentrations were not predictive of sediment toxicity, but H. azteca survival was explained by DPASV measurements that varied by ≤4%. In order to make defensible estimates of the potential risk of metals in sediments or water, it is essential to identify the fraction of total metal that is bioavailable. In these experiments, DPASV was useful for measuring bioavailable copper in aqueous and sediment tests with H. azteca.
Spermiotoxicity and embryotoxicity of heavy metals in the echinoid Paracentrotus lividus
Authors: Warnau Michel , Temara Ali , Jangoux Michel , Dubois Philippe , Iaccarino Mario , De Biase Antonella , Pagano Giovanni
Published: March 2010

Spermio- and embryotoxicities of Cu, Ag, Cd, and Hg were investigated in Paracentrotus lividus, the dominant echinoid species of the Mediterranean. Spermiotoxicity was studied by assessing the effects of sperm exposure on fertilization rate (FR) as well as on the induction of transmissible damages to the offspring. Embryotoxicity was studied by assessing developmental defects in larvae exposed to the tested metals throughout their development. Sperm exposures resulted in significant decreases of FR, depending on both metal concentration and duration of the exposure. Lowest spermiotoxic concentrations recorded when sperm were exposed for 75 min to the metals were 10−7 M Hg(II), 10−6 M Ag(I), 10−5 M Cu(II), and 10−5 M Cd(II). Tested metals did not exert any transmissible damage to spermatozoa that could result in larval malformations in the offspring, even for concentrations that dramatically reduced FR. Single-element exposures of embryos for 72 h resulted in developmental defects whose occurrence and severity showed a steep dose dependence, indicating that once a threshold is reached, any further increase in toxicant concentration rapidly enhances the impairment of target function(s). Those observations suggest the involvement of a saturable protective mechanism. Lowest observed embryotoxic concentrations of the metals were 10−7 M Hg(II), 2.5 × 10−7 M Ag(I), 5 × 10−7 M Cu(II), and 10−5 M Cd(II) and are in the range of concentrations reported in heavily polluted marine environments. Thus, the possibility of impairment of echinoid development actually exists in metal-contaminated marine environments, possibly threatening echinoid populations in those environments.
Reduced biodegradability of desorption-resistant fractions of polycyclic aromatic hydrocarbons in soil and aquifer solids
Authors: White Jason C. , Alexander Martin
Published: March 2010

Less of the desorption-resistant fractions of phenanthrene and naphthalene than freshly added phenanthrene and naphthalene was mineralized in columns of aquifer solids, loam, or muck. Slurrying columns of hydrocarbon-amended aquifer solids, loam, or muck enhanced the rate and extent of mineralization of desorption-resistant phenanthrene and naphthalene, but degradation was still less than in slurries amended with fresh compound. A substantial portion of the desorption-resistant compound remained undegraded in the slurry. A surfactant and methanol increased the mineralization of resistant phenanthrene in slurries of loam. A mixed culture of microorganisms enriched on desorption-resistant phenanthrene degraded twice as much of this fraction of compound as a pseudomonad. We suggest that predictions of the environmental fate of toxic chemicals require information on the biodegradability of the fraction of a compound that is resistant to desorption.
Distributions of key exposure factors controlling the uptake of xenobiotic chemicals in an estuarine food web
Authors: Iannuzzi Timothy J. , Harrington Natalie W. , Shear Nadine M. , Curry Cynthia L. , Carlson-Lynch Heather , Henning Miranda H. , Su Steave H. , Rabbe David E.
Published: March 2010

A critical evaluation of literature on the behavior, physiology, and ecology of common estuarine organisms was conducted in an attempt to develop probabilistic distributions for those variables that influence the uptake of xenobiotic chemicals from sediments, water, and food sources. The ranges, central tendencies, and distributions of several key parameter values were identified for dominant organisms from various trophic levels, including the polychaete Nereis virens, mummichog (Fundulus heteroclitus), blue crab (Callinectes sapidus), and striped bass (Morone saxatilis). The exposure factors of interest included ingestion rate for various food sources, growth rate, respiration rate, excretion rate, body weight, wet/dry weight ratio, lipid content, chemical assimilation efficiency, and food assimilation efficiency. These exposure factors are critical to the execution of mechanistic food web models, which, when properly calibrated, can be used to estimate tissue concentrations of nonionic chemicals in aquatic organisms based on knowledge of the bioenergetics and feeding interactions within a food web and the sediment and water concentrations of chemicals. In this article we describe the use of distributions for various exposure factors in the context of a mechanistic bioaccumulation model that is amenable to probabilistic analyses for multiple organisms within a food web. A case study is provided which compares the estimated versus measured concentrations of five polychlorinated biphenyl (PCB) congeners in a representative food web from the tidal portion of the Passaic River, New Jersey, USA. The results suggest that the model is accurate within an order of magnitude or less in estimating the bioaccumulation of PCBs in this food web without calibration. The results of a model sensitivity analysis suggest that the input parameters which most influence the output of the model are both chemical and organism specific.
Characteristics of butyltin accumulation and its biomagnification in steller sea lion (Eumetopias jubatus)
Authors: Kim Gi Beum , Tanabe Shinsuke , Tatsukawa Ryo , Loughlin Thomas R. , Shimazaki Kenji
Published: March 2010

The present study was conducted to examine sex difference, age, and temporal trends of butyltin accumulation and its biomagnification in Steller sea lion (Eumetopias jubatus) collected from Alaska, USA, during 1976–1985 and from Hokkaido, Japan, during 1994–1995. Average concentration of total butyltin compounds (ΣBTs) in the liver of Steller sea lion from Alaska (19 ng/g wet weight) was much lower than those from western and eastern Hokkaido, Japan (150 and 220 ng/g), respectively. This result suggests that Japanese coastal waters are contaminated with BTs in comparison with those of Alaska. In most samples, dibutyltin (DBT) residues were retained at higher levels than tributyltin (TBT), suggesting the degradation of TBT to DBT in the liver. Sex difference and age-dependent accumulation of BTs residues were not found in Steller sea lion. Similarly, no prominent temporal trend in BT concentrations was observed between 1976 and 1985. Nevertheless, the annual consumption of organotin compound was doubled in the United States during the same period. These results suggest that the butyltin compounds are degraded faster than the intake from diet in Steller sea lion. The biomagnification factor of BTs in Steller sea lion was low (0.15–4.6; mean, 0.6), indicating that this animal is unlikely to magnify BTs due to rapid degradation and excretion.
Evaluation of metal/acid-volatile sulfide relationships in the prediction of metal bioaccumulation by benthic macroinvertebrates
Authors: Ankley Gerald T.
Published: March 2010

Recent studies have demonstrated that the toxicity of divalent cationic metals (cadmium, copper, lead, nickel, and zinc) in sediments can be controlled through binding to acid-volatile sulfide (AVS). When the molar concentration of AVS exceeds that of the metals (i.e., the metal/AVS ratio is less than unity), they exist predominantly as insoluble metal sulfides, which presumably are not biologically available. Thus, at metal/AVS ratios less than 1, toxicity of sediment-associated metals to benthic macroin-vertebrates has not been observed. However, bioaccumulation may provide a more direct assessment of contaminant bioavailability than the presence or absence of toxicity. The purpose of this report is to comprehensively review available literature on metal bioaccumulation versus sediment metal/AVS relationships to further examine the tenet that AVS controls metal bioavailability. In all, 12 studies were evaluated; these ranged from short-term (10-d) laboratory experiments with metal-spiked or field-collected sediments containing cadmium, copper, lead, nickel, and/or zinc to long-term (> 1-year) field studies with sediments spiked with cadmium or zinc. Test organisms included mollusks, oligochaetes, polychaetes, amphipods, and midges. The preponderance of studies indicated reduced accumulation of metals at sediment metal/AVS ratios of less than 1. However, there were exceptions to this general observation, two of which occurred in short-term laboratory experiments with cadmium- or nickel-spiked sediments. In these studies there appeared to be a linear accumulation of metals with increasing sediment metal concentrations irrespective of the metal/AVS ratio. Although there is experimental evidence suggesting that significant bioaccumulation of metals does not occur when there is sufficient AVS available to bind them, the existence of at least some data to the contrary indicates the need for further research relative to factors controlling the bioaccumulation of metals from sediments.
A model of the oxidation of iron and cadmium sulfide in sediments
Authors: Di Toro Dominic M. , Mahony John D. , Hansen David J. , Berry Walter J.
Published: March 2010

A model is presented for the temporal and vertical variation of acid-volatile sulfide (AVS), simultaneously extracted cadmium (SEMcd), and cadmium interstitial water concentration in sediments. The model is based on the one-dimensional advective-dispersive mass balance equation. Transport by particle and pore-water mixing is considered. The state variables include the components of AVS and SEMcd, namely iron sulfide (FeS) and cadmium sulfide (CdS), and sorbed + pore-water cadmium (CdT). In addition, particulate organic carbon (POC), iron oxyhydroxide, and dissolved oxygen are explicitly modeled. The oxidation, displacement, and partitioning reactions that are sources and sinks of the state variables are included. The model is applied to three experimental data sets. Two of these employed marine sediments with typical organic carbon and AVS concentrations. The third employed a freshwater sediment with a high POC and low AVS. The calibration produced similar partitioning parameters on an organic carbon basis for both sediments. However, the oxidation and partitioning behavior of the FeS in the low AVS freshwater sediment was distinctly different from the high AVS cases. The model successfully reproduces the major features of the experimental data: the progressive decrease in AVS and SEMcd, and an increase in the SEMcd to AVS ratio in the surface layers. It is less successful in reproducing the pore-water cadmium concentrations.
Partitioning of metals to sediment organic carbon
Authors: Mahony John D. , Di Toro Dominic M. , Gonzalez Adrian M. , Curto Mark , Dilg Maureen , De Rosa Laurie D. , Sparrow Leslie A.
Published: March 2010

The partition coefficients and sorption capacities for cadmium, copper, and lead in freshwater sediments are derived from fitting a Langmuir isotherm to data from 14 sediments. The metal activity in the solution phase was measured using specific ion electrodes. The metal sorption due to acid-volatile sulfide was subtracted from the total sorbed metal to produce the metal bound to other sediment phases. Organic carbon normalized isotherms provide a reasonable representation of the metal sorption. Partition coefficients and capacities are calculated for pH = 6, 7, and 8 (for Cd). The organic carbon normalized isotherm parameters for the sediments are compared to those reported for soils and sludges. The comparisons for cadmium exhibit differences for which no ready explanations are available. For copper and lead, however, the differences can be attributed to the use of specific ion electrodes for measuring metal activity in the sediment experiments. The cadmium sediment partition coefficients contribute a small increment to the sediment quality criteria. For copper and lead, however, the additional binding to sediment organic carbon is significant and can amount to 1 to 10 and 10 to 100 μmol/g dry weight for lead and copper, respectively, depending on the organic carbon concentration of the sediment.
Estimation of partition coefficients for five trace metals in sandy sediments and application to sediment quality criteria
Authors: Hassan S.M. , Garrison A.W. , Allen H.E. , Di Toro D.M. , Ankley G.T.
Published: March 2010

Six low-capacity natural adsorbents-were identified for the five metal cations (cadmium, copper, nickel, lead, and zinc) for which the U.S. Environmental Protection Agency is developing sediment quality criteria (SQC). The adsorbents were commercial sea sand and chromatographic sand (both from natural sources) and four sandy sediments collected from different parts of the continental United States. Batch adsorption experiments were conducted for each sediment with a mixture of the five cations at low concentrations (from about 15 to 700 μg/L) using a 48-h equilibration time. The distribution coefficients (Kds) were calculated using the initial linear segment of the plotted adsorption isotherms; selection of the linear segment involved repetitive regression analysis of selected data points. Chromatographic sand at pH 3.7 showed the lowest adsorption capacity for all the metal cations. An increase in pH of the medium generally resulted in a higher Kd, whereas an increase in ionic strength resulted in a lower Kd Chromatographic sand, especially at low natural pH levels, may serve as a limiting adsorbent or a benchmark for maximum pore-water concentrations for these five metal cations because its associated pore water would contain higher levels of the cations than other sediments. These measured Kds, which are expected to be minimum values for natural sediments, were applied to screen sediment samples for SQC. An equation that can predict the Kd for each of the five metals for sandy sediments at neutral and lower pH levels was derived from the regression of the measured Kds against the pH of the six sediments used in this study. This equation was tested with a data set from Lake Michigan sediment samples. Porewater metal concentrations calculated from the predicted Kd values were used to predict whether a sediment would pass SQC in terms of predicted interstitial water criteria toxic units; 16 of 38 of these sediments were predicted not to exceed proposed SQC for metals.
Estimation of polycyclic aromatic hydrocarbon concentrations in the water column based on tissue residues in mussels and salmon: An equilibrium partitioning approach
Authors: Neff Jerry M. , Burns William A.
Published: March 2010

Equilibrium partitioning was used to estimate concentrations of dissolved polycyclic aromatic hydrocarbons (PAHs) in the water column from PAH residues in tissues of mussels and juvenile pink salmon collected from coastal marine waters affected by the Exxon Valdez oil spill. Estimated concentrations were within factors of 2 to 5 for fish and 5 to 10 for mussels of average total dissolved and particulate PAHs measured in concurrent water samples. Temporal trends of estimated and measured water‒column PAH concentrations were comparable. Water‒column PAH concentrations estimated from residues in tissues of mussels (Mytilus trossulus) were higher than estimates based on residues in tissues of juvenile pink salmon (Oncorhynchus gorbuscha). Possible reasons for this difference include seasonal variations in mussel lipid content, differences in PAH uptake and depuration rates between fish and mussels, differences in how fish and mussels interact with particulate oil, and possible short exposure times for juvenile pink salmon. All of these factors may play a role. In any event, estimates of dissolved PAHs in the water column, based on PAH residues in either fish or mussel tissue, confirm that PAH concentrations generally did not exceed water quality standards for protection of marine life.
Action of insecticides on the cellular immune reaction of Drosophila melanogaster against the parasitoid Leptopilina boulardi
Authors: Delpuech Jean-Marie , Frey Françoise , Carton Yves
Published: March 2010

Drosophila larvae infested by endoparasitoids can survive the infestation by an immune reaction leading to the encapsulation and destruction of parasitoid eggs. Conversely, parasitoids can escape the encapsulation by inhibiting this immune reaction. These processes could be influenced by exposure to pesticides, so an experiment was designed to investigate this possibility. Two strains of Drosophila melanogaster Meigen were tested, one with a high capacity for encapsulation (reactive strain) and the other with a very low capacity for encapsulation (nonreactive strain). We compared their immune reaction capacity after infestation when reared on a medium containing or not containing an LD30 of insecticide. Six different insecticides were tested. Two appeared to modify the effectiveness of the immune reaction. When the reactive strain was tested, dieldrin decreased the success of the immune reaction by 25%, and endosulfan, by 23%. Endosulfan also decreased the encapsulation rate of this strain by 26%. With the nonreactive strain no effect was observed regardless of insecticide. The possible causes of these weakening of encapsulation ability and their consequences on the evolution of these species are discussed.
Purification and immunochemical detection of β-naphthoflavone-and phenobarbital-induced avian cytochrome P450 enzymes
Authors: Brown Randal L. , Levi Patricia E. , Hodgson Ernest , Melancon Mark J.
Published: March 2010

Livers from mallards (Anas platyrhynchos) were treated with either β-naphthoflavone (50 mg/kg) or phenobarbital (70 mg/kg). Purification of induced hepatic cytochrome P450 was accomplished using both DEAE and hydroxyapatite columns, as well as sodium dodecyl sulfate polyacrylamide gel electrophoresis separation. Polyclonal antibodies to these proteins were then produced in young male New Zealand White rabbits. β-Naphthoflavone (βNF)- and phenobarbital (PB)-treated red-winged blackbird, screech owl, European starling, and lesser scaup liver microsomes were analyzed in western blots for species cross-reactivity. Although all four of these avian species exhibited cross-reactivity with antibodies to βNF-induced mallard P450, all but the lesser scaup revealed a protein of higher molecular weight than that of the βNF-induced mallard. In addition, only the lesser scaup exhibited cross-reactivity with the anti-PB-induced mallard P450 antibodies.
Assessing the effects of modifying factors on pentachlorophenol toxicity to earthworms: Applications of body residues
Authors: Fitzgerald Dean G. , Warner Kathryn A. , Lanno Roman P. , Dixon D. George
Published: March 2010

This study examined the toxicokinetic relationship between critical body residues (CBRs) of pentachlorophenol (PCP) at lethality, soil PCP concentrations, and modifying factors of toxicity such as body size, species, temperature, and soil type during 28-d bioassays with earthworms. Eisenia fetida (0.2–0.4 g) were exposed to PCP at 15 and 24°C in artificial soil and at 24°C in Brookston clay. Lumbricus terrestris (3.3–4.6 g) and Eudrilus eugeniae (1.5–2.7 g) were exposed in artificial soil at 15 and 24°C, respectively. Soil PCP concentrations ranged from 0 to 6.75 mmol PCP/kg soil (dry weight), and body residues were measured by gas chromatography following cryoextraction of freeze-dried earthworms. Comparisons of toxicity were made using incipient lethal levels (ILLs) and CBRs at lethality. The equations estimated by nonlinear curve fitting of a one-compartment, first-order kinetics model provided a good fit to the observed data for all species, temperatures, and soil types at which tests were conducted. Incipient lethal levels for L. terrestris (0.72 mmol/kg soil) and E. eugeniae (0.63 mmol/kg soil) were similar and significantly higher than those for all E. fetida treatments. Incipient lethal levels for E. fetida exposed to PCP in artificial soil at 15 and 24°C were similar and lower than the ILL for E. fetida exposed to PCP in Brookston clay. The toxicity half-lives were similar for all E. fetida treatments but were higher than for the larger worms, L. terrestris and E. eugeniae, which were similar. Mean CBRs at lethality for E. fetida tested in artificial soil at 24°C ranged from 0.33 to 0.74 mmol/kg (wet weight) over the range of soil PCP exposure concentrations from 0.12 to 3.75 mmol PCP/kg. Mean CBRs for E. fetida exposed to PCP at 24°C in Brookston clay ranged from 0.51 to 1.59 mmol PCP/kg (wet weight) over the same range of soil PCP concentrations and were not significantly different. Critical body residues for E. fetida (15°C), L. terrestris, and E. eugeniae tested in artificial soil at 2.10 mmol PCP/kg ranged between 0.34 and 0.80 mmol PCP/kg. Residues in surviving worms were either similar to or lower than those in dead worms. Similar CBRs in three species of earthworms differing 10-fold in body size, and for E. fetida exposed to PCP concentrations ranging over more than two orders of magnitude in two different soil types, demonstrate that body residues can act to more effectively integrate the relationship between test organism, exposure, and mortality than soil toxicant concentrations alone.
Ecotoxicology of tropical marine ecosystems
Authors: Peters Esther C , Gassman Nancy J , Firman Julie C , Richmond Robert H , Power Elizabeth A
Published: March 2010

The negative effects of chemical contaminants on tropical marine ecosystems are of increasing concern as human populations expand adjacent to these communities. Watershed streams and ground water carry a variety of chemicals from agricultural, industrial, and domestic activities, while winds and currents transport pollutants from atmospheric and oceanic sources to these coastal ecosystems. The implications of the limited information available on impacts of chemical stressors on mangrove forests, seagrass meadows, and coral reefs are discussed in the context of ecosystem management and ecological risk assessment. Three classes of pollutants have received attention: heavy metals, petroleum, and synthetic organics such as herbicides and pesticides. Heavy metals have been detected in all three ecosystems, causing physiological stress, reduced reproductive success, and outright mortality in associated invertebrates and fishes. Oil spills have been responsible for the destruction of entire coastal shallow-water communities, with recovery requiring years. Herbicides are particularly detrimental to mangroves and seagrasses and adversely affect the animal-algal symbioses in corals. Pesticides interfere with chemical cues responsible for key biological processes, including reproduction and recruitment of a variety of organisms. Information is lacking with regard to long-term recovery, indicator species, and biomarkers for tropical communities. Critical areas that are beginning to be addressed include the development of appropriate benchmarks for risk assessment, baseline monitoring criteria, and effective management strategies to protect tropical marine ecosystems in the face of mounting anthropogenic disturbance.
Marine heterotrophic bacteria as indicators in the quality assessment of coastal waters: Introducing the “apparent bacterial concentration” approach
Authors: Sbrilli Giancarlo , Cruscanti Marco , Bucci Mario , Gaggi Carlo , Bacci Eros
Published: March 2010

A simplified fingerprint, obtained by counting the colonies of luminescent and nonluminescent bacteria developing on filters plated on a solid culture medium, was applied to obtain an indication of coastal water quality. Results from a reference area and three polluted sites (essentially by urban sewage) and their variations during the year are reported. A tentative characterization of the “clean” and polluted sites is made.