bluuebunny/crossref_metadata_2025_split huggingface dataset:
Size-dependent response of macroinvertebrates to metals in experimental streams
Authors: Kiffney Peter M. , Clements William H. 
Published: March 2010

Abstract
Our previous research has shown that the effects of metals on stream benthic invertebrate populations and communities can vary within and between locations. With this in mind, we examined whether invertebrate body size could explain some of the variation in metal sensitivity within a species. Benthic macroinvertebrates from a pristine Rocky Mountain foothills' stream were collected using artificial substrates and exposed to a mixture of Cd, Cu, and Zn in stream microcosms for 10 d at their respective Colorado chronic criterion levels (4.0, 5.0, and 50 μg/L). The effects of metals on the ephemeropterans Baetis tricaudatus (Baetidae), Ephemerella infrequens (Ephemerellidae), and Rhithrogena hageni (Heptageniidae) and the plecopteran Pteronarcella badia (Pteronarcyidae) were size dependent, as there was an inverse relationship between body size and survivorship. These results may have important implications for setting water-quality criteria for metals and for using benthic invertebrates in biological assessments.
Effects of in vitro exposure of beluga whale splenocytes and thymocytes to heavy metals
Authors: Bernier Jacques , Fournier Michel , De Guise Sylvain , Martineau Daniel , Beland Pierre 
Published: March 2010

Abstract
The effects of in vitro exposure of beluga whale splenocytes and thymocytes to different concentrations of mercury chloride (HgCl2), cadmium chloride (CdCl2), and lead chloride (PbCl2) were evaluated. The cells were cultured for 66 h with either concanavalin A (Con-A), phytohemagglutinin-P, or without mitogen, after which percentage of cell death and proliferation were evaluated. Increased percentage of cell death was observed in Con-A-stimulated thymocytes cultured with HgCl2, while the viability of splenocytes was not affected by exposure to metals. Decreased splenocyte and thymocyte proliferation was observed with the highest concentration of HgCl2 and CdCl2 (10−5 M), while lower concentrations of these metals (10−6 and 10−7 M) as well as all the different concentrations of PbCl2 (10−4, 10−5, and 10−6 M) did not significantly influence cell proliferation. Concentrations of metals that were found to affect the proliferation of beluga lymphocytes are similar to those found in the liver of beluga whales from wild populations.
Organochlorine dynamics in the pelagic food web of lake baikal
Authors: Kucklick John R. , Harvey H. Rodger , Baker Joel E. , Ostrom Peggy H. , Ostrom Nathaniel E. 
Published: March 2010

Abstract
In July and August 1993, samples were collected from Lake Baikal both to document organochlorine concentrations and to relate the contaminant levels to trophic position and lipid concentration. High-volume water samples and representatives of the major organisms in the food web, including zooplankton, fish, and seals, were collected. Dissolved and particulate water samples were analyzed for polychlorinated biphenyls (PCBs; 74 congeners) and hexachlorobenzene. Biota samples were analyzed for PCBs, hexachlorocyclohexanes, chlordane and related compounds, dieldrin, dichlorodiphenyltrichloroethane (plus metabolites), and toxaphene. Specific lipid classes were measured in fish since these were postulated to affect organochlorine concentrations. Stable nitrogen (815N) and carbon (813C) isotopic compositions were determined in all samples except seal blubber as a measure of trophic position. Total PCBs in surface water ranged from 130 pg/L in the lake's northern basin to 1,900 pg/L in the southern basin. Total PCBs in fish ranged from 60 to 710 ng/g (wet weight), with differences mostly attributed to total lipid content rather than to specific lipid classes. The PCB bioaccumulation factor was significantly correlated with log Kow, whereas the PCB bioconcentration factor was not. The transfer of contaminants through the food web was likely at steady state, whereas the uptake of PCBs from the water was not. This indicates recent PCB contamination.
Volatilization and sorption of dimethylsilanediol in soil
Authors: Lehmann Robert G. , Miller Jack R. 
Published: March 2010

Abstract
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

Abstract
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

AbstractThe 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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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 &gt; 25°C &gt; 15°C) and moisture (−3 kPa &gt; −33 kPa &gt; −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 (&gt;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

Abstract
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

Abstract
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

Abstract
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

Abstract
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.