Showing papers in "Environmental Toxicology and Chemistry in 1990"
TL;DR: In this paper, it was shown that acid volatile sulfide (AVS) is the sediment phase that determines the LC50 for cadmium in the marine sediments tested.
Abstract: The toxicity of chemicals in sediments is influenced by the extent that chemicals bind to the sediment. It is shown that acid volatile sulfide (AVS) is the sediment phase that determines the LC50 for cadmium in the marine sediments tested. Although it is well known that metals can form insoluble sulfides, it apparently has not been recognized that AVS is a reactive pool of solid phase sulfide that is available to bind with metals. Amphipod sediment toxicity tests were conducted in the laboratory and the observed amphipod LC50s on a normalized cadmium concentration basis, [Cd]/[AVS], is the same for sediments with over an order of magnitude difference in dry weight normalized cadmium LC50s.
Because other toxic metals also form insoluble sulfides, it is likely that AVS is important in determining their toxicity in sediments as well. Most freshwater and marine sediments contain sufficient acid volatile sulfide for this phase to be the predominant determinant of toxicity. The other sorption phases are expected to be important only for low AVS sediments, for example, fully oxidized sediments. From the point of view of sediment quality criteria the other sorption phases would be important for metals with large partition coefficients and large chronic water quality criteria.
800 citations
TL;DR: Comparison with published data for other invertebrates indicated that Caenorhabditis elegans was more sensitive to Pb, Cr and Be and less sensitive to As than any of the other organisms that have been tested.
Abstract: A promising aquatic toxicity test has been developed using a species of free-living nematode, Caenorhabditis elegans. The testing was performed with soluble forms of Ag, Hg, Cu, Be, Al, Pb, Cr, As, Tl, Zn, Cd, Ni, Sr and Sb. The LC50 values for 1 to 4 d of exposure were determined and compared to the published invertebrate data. With Caenorhabditis elegans Pb, Cr and Cd were found to have the lowest 96-h LC50 (0.06 mg/L) and Sr had the highest LC50 (465 mg/L). All the metals except As have a significantly lower 96-h LC50 (from 20 to 15,000 times lower) than 24-h LC50. Comparison with published data for other invertebrates indicated that Caenorhabditis elegans was more sensitive to Pb, Cr and Be and less sensitive to As than any of the other organisms that have been tested. Given the ease in culturing and the extensive knowledge of the basic biology of Caenorhabditis elegans, coupled with the ecological abundance of nematodes, the method is worthy of further study to determine its usefulness as an aquatic test species.
443 citations
TL;DR: In this paper, fish were sampled from 35 drainage and seepage lakes in the upper Michigan peninsula and Wisconsin in conjunction with Phase II of the U.S. Environmental Protection Agency's Eastern Lake Survey to explore the relationship between physicochemical characteristics of lakes and mercury concentrations in fish tissue.
Abstract: Fish were sampled from 35 drainage and seepage lakes in the upper Michigan peninsula and Wisconsin in conjunction with Phase II of the U.S. Environmental Protection Agency's Eastern Lake Survey to explore the relationship between physicochemical characteristics of lakes and mercury concentrations in fish tissue. The lakes were selected using a stratified random design weighted for low pH to assess acidification effects on mercury bioaccumulation. Muscle tissue from yellow perch (Perca flavescens), northern pike (Esox lucius), white sucker (Catostomus commersoni) and largemouth bass (Micropterus salmoides) was analyzed for total and methylmercury. Differences in mercury concentrations were found between species, and methylmercury accounted for 99% of total mercury. Relationships were examined between tissue concentrations of mercury in yellow perch and lake physicochemical variables including pH, acid neutralizing capacity (ANC), calcium, conductivity, aluminum, total phosphorus, dissolved organic carbon, color, sulfate, lake area, lake depth, watershed area, Secchi depth and elevation. Mercury concentrations were negatively correlated with pH and ANC for both seepage and drainage lakes, but correlations with other water-quality characteristics varied with lake type. Dissolved organic carbon had a negative correlation with fish mercury accumulation in seepage lakes, but not in drainage lakes. Mercury concentrations had a positive correlation with age, weight and length in yellow perch.
385 citations
TL;DR: Analysis of swimming patterns provides even higher resolution for analysis of swimming behavior, and increased availability of the instrumentation necessary for such measurements should facilitate use of this approach.
Abstract: Swimming behavior of fish is impaired by exposure to a diversity of contaminants. Gross aberrations in swimming can be qualitatively assessed while subtle changes in swimming behavior arising from sublethal exposures can be detected through a more detailed analysis of this response. Compared to other swimming behavior variables, the physical capacity to swim against water flow tends to be affected at relatively high toxicant concentrations and often presages mortality. Orientation to water flow, however, is altered at sublethal concentrations. Frequency of activity is a more sensitive measure in detecting contamination than measurements of survival alone. Alterations in swimming behavior have been detected during exposures to various contaminants at concentrations as low as 0.7 to 5% of their LC50 values and at concentrations that subsequently inhibited growth after longer periods of exposure. Analysis of swimming patterns provides even higher resolution for analysis of swimming behavior, and increased availability of the instrumentation necessary for such measurements should facilitate use of this approach. Fish swimming activity can easily be incorporated in test protocols to expand the sensitivity of standard toxicity tests.
364 citations
TL;DR: In this article, the amount of methylmercury produced in a lake can play a major role in the bioaccumulation of fish from remote, low alkalinity and low pH lakes.
Abstract: Recent studies have demonstrated elevated levels of mercury in fish from remote, low alkalinity and low pH lakes. The mechanisms of this enhanced bioaccumulation are poorly understood, but the amount of methylmercury produced in a lake can play a major role. Decreased pH stimulates methylmercury production at the sediment-water interface and possibly in the aerobic water column. Decreased pH also decreases loss of volatile mercury from lake water and increases mercury binding to particulates in water – factors that may increase methylation at low pH by enhancing the bioavailability of mercury for methylation. In anoxic subsurface sediments, decreased pH decreases the rate of mercury methylation, suggesting that methylmercury formation in the water column and at the sediment-water interface may be most important in acidified lakes. Sulfate-reducing bacteria are important mercury methylators in acidified lakes. Whether enhanced sulfate reduction stimulates methylmercury production in low pH lakes is presently unclear, although most of the available data do not support this hypothesis.
358 citations
TL;DR: In this article, the fate of 14 polycyclic aromatic hydrocarbon (PAH) compounds was evaluated with regard to interphase transfer potential and mechanisms of treatment in soil under unsaturated conditions.
Abstract: The fate of 14 polycyclic aromatic hydrocarbon (PAH) compounds was evaluated with regard to interphase transfer potential and mechanisms of treatment in soil under unsaturated conditions. Volatilization and abiotic and biotic fate of the PAHs were determined using two soils not previously exposed to these compounds. Volatilization accounted for approximately 30 and 20% loss of naphthalene and 1-methylnaphthalene, respectively; for the remaining compounds, volatilization was negligible. Abiotic reactions accounted for approximately 2 to 20% of the reduction in concentration in solvent extracts for two- and three-ring PAH compounds; no statistically significant reduction was observed for PAH compounds containing greater than three aromatic rings. Biotic mechanisms were quantified as first-order rate constants corrected for volatilization and abiotic mechanisms. Half-life values increased from approximately 2 to 60 to more than 300 d for two-, three- and four- and five-ring PAH compounds, respectively. In general, biological degradation rates were not significantly different between the two soils. Information concerning interphase transfer potential and mechanisms of treatment provides the basis for a rational approach to remediation of soil contaminated with PAH compounds.
228 citations
TL;DR: Toxicity of sediment pore water from 13 sites in the lower Fox River/Green Bay watershed was assessed using a number of test species as discussed by the authors, and the identification of ammonia, a naturally occurring compound in sediments, as a potentially important sedimentassociated toxicant has implications for sediment toxicity assessment and control, not only in the Fox River and Green Bay, but in other freshwater and marine systems as well.
Abstract: Toxicity of sediment pore water from 13 sites in the lower Fox River/Green Bay watershed was assessed using a number of test species. Sediment pore water from the 10 lower Fox River sites exhibited acute toxicity to fathead minnows (Pimephales promelas) and Ceriodaphnia dubia, and pore water samples from all 13 sites were chronically toxic to C. dubia. Sediment pore water from seven of the sampling sites was toxic to Selenastrum capricornutum, but none of the samples were toxic to Photobacterium phosphoreum. Toxicity characterization, identification and confirmation procedures indicated that a significant amount of the acute toxicity of the pore water to fathead minnows and C. dubia was due to ammonia. The identification of ammonia, a naturally occurring compound in sediments, as a potentially important sediment-associated toxicant has implications for sediment toxicity assessment and control, not only in the Fox River and Green Bay, but in other freshwater and marine systems as well.
194 citations
TL;DR: In this article, the formation of slowly reversible sorbed fractions of various halogenated alkanes and alkenes in two surface soils was described, and the residual fraction in the soil was determined independently after extraction with hot acetone, whose efficacy was demonstrated.
Abstract: This study describes the formation of slowly reversible sorbed fractions of various halogenated alkanes and alkenes in two surface soils. After the initial sorption equilibration period, the compounds were desorbed by one of two methods. The first used repetitive batch extraction with water. After 16 extractions of 24 to 72 h each, concentrations in the aqueous phase reached low values and a slow desorbing, residual fraction remained in the soil. The residual fraction in the soil was determined independently after extraction with hot acetone, whose efficacy was demonstrated. During desorption, apparent soil-water distribution coefficients increased progressively to as much as 200 times greater than equilibrium sorption coefficients, Kd, obtained separately from sorption isotherms. With increasing sorption equilibration time, the residual became greater in magnitude and less mobile. The second desorption method simulated desorption to infinite dilution over a 96 h period by using Tenax GC polymeric adsorbent beads included in the suspension as a sink for desorbed chemical. Control experiments proved the usefulness of Tenax and showed that desorption from the soil was rate limiting. All compounds studied formed slowly reversible fractions in the soils. This fraction amounted to several percent of the total sorbed from solution. The results indicate that formation of slowly reversible fractions is probably typical of nonpolar organic compounds, including those with weak sorbing tendencies.
188 citations
TL;DR: Sediment quality criteria derived from the equilibrium partitioning model and water quality criteria would protect sensitive benthic invertebrates, and there was a close correspondence between estimates of sediment quality for fluoranthene based on distinctly different methodologies.
Abstract: The toxicity of fluoranthene in sediment to the marine benthic amphipods, Rhepoxynius abronius (Barnard) and Corophium spinicorne (Stimpson) was determined in relation to the equilibrium partitioning approach to the development of sediment quality criteria. Toxicity tests were conducted with well-sorted fine sands at three levels of organic carbon (OC), 0.18, 0.31 and 0.48%. Measured interstitial water concentrations of fluoranthene less than 50 μg/L were highly correlated with predictions based on the equilibrium partitioning model. LC50s based on bulk (total) fluoranthene concentrations increased significantly with increasing sediment OC. LC50s based on fluoranthene concentrations in interstitial water were not significantly different between 0.18 and 0.48% OC or between 0.31 and 0.48% OC, but the LC50 at 0.31% OC was significantly higher than that at 0.18% OC. The regression of sediment OC on bulk fluoranthene LC50 was linear, indicating that the concentration of fluoranthene in interstitial water was constant at equitoxic conditions, as predicted by the equilibrium partitioning model. The 10-d LC50 of fluoranthene in interstitial water (23.8 μg/L) was intermediate between the U.S. Environmental Protection Agency's (U.S. EPA) acute (40 μg/L) and chronic (16 μg/L) water quality values for fluoranthene. Within the limitations of these experiments (i.e., one chemical, two species, sandy sediment with low carbon content), the results indicate that sediment quality criteria derived from the equilibrium partitioning model and water quality criteria would protect sensitive benthic invertebrates. The epibenthic, tube-dwelling Corophium was less sensitive to test sediments than the infaunal, free-burrowing Rhepoxynius, possibly because of different routes of exposure to fluoranthene. There was a close correspondence between estimates of sediment quality for fluoranthene based on distinctly different methodologies including equilibrium partitioning, apparent effects threshold, toxicity tests applied to experimentally spiked sediment and toxicity tests applied to field-collected sediment.
157 citations
TL;DR: In fish in which the cytochrome P-450 system was inhibited with piperonylbutoxide, the bioconcentration factor of 2,8-dichlorodibenzo-p-dioxin was significantly higher than that in fish which were not pretreated with the blocking agent.
Abstract: In spite of their hydrophobicity, not all polychlorinated dibenzo-p-dioxin (PCDD) and dibenzofuran (PCDF) congeners accumulate significantly in fish or other aquatic organisms. This is found both in laboratory experiments and in organisms that are sampled in the natural environment. Hitherto, this congener-specific accumulation could not adequately be explained or predicted.
Many PCDDs and PCDFs with four or more chlorine atoms, such as octachlorodibenzo-p-dioxin, are taken up very slowly, if at all, during aqueous exposure. Furthermore, the uptake rates after dietary exposure of these congeners are significantly less than those of other chlorinated aromatic hydrocarbons with comparable hydrophobicity, such as polychlorinated benzenes and biphenyls. A lack or a low rate of membrane permeation may help to explain this phenomenon.
For several higher chlorinated congeners and for most of the lower chlorinated dioxins and furans, the rates of uptake after dietary and aqueous exposure are comparable to those of other hydrophobic aromatic hydrocarbons. The relatively low bioconcentration and biomagnification factors of these lower chlorinated PCDDs and PCDFs should thus be explained by high rates of excretion, probably by biotransformation. In several studies, polar metabolites have been identified. Furthermore, in fish in which the cytochrome P-450 system was inhibited with piperonylbutoxide, the bioconcentration factor of 2,8-dichlorodibenzo-p-dioxin was significantly higher than that in fish which were not pretreated with the blocking agent. These results support the hypothesis that biotransformation is of paramount importance for the bioaccumulation of several PCDDs and PCDFs.
153 citations
TL;DR: The utility and limits of applicability of a simple equilibrium partitioning model for predicting the maximum concentration of neutral organic compounds which can be accumulated by infaunal organisms exposed to a contaminated sediment were examined in this paper.
Abstract: The utility and limits of applicability of a simple equilibrium partitioning model for predicting the maximum concentration of neutral organic compounds which can be accumulated by infaunal organisms exposed to a contaminated sediment were examined. Accumulation factors (AFs) for PCBs, the lipid normalized PCB concentration in organisms divided by the organic carbon normalized PCB concentration in sediments, were measured for PCBs in infaunal mollusks and polychaetes at field sites with a range of sediment Aroclor (A-1254) and total organic carbon (TOC) concentrations. The average AFs for A-1254 were found to be higher (x = 4.94; range 3.76–7.27) at sites with lower contaminant concentrations (15.0–48.3 ng A-1254/g dry sediment) than at more contaminated sites (328–9,200 ng/g), where AFs were lower (x = 2.62; range 1.14–5.04). AF data grouped on the basis of sediment A-1254 and TOC concentration differed statistically between, but not within each group. Significant differences in mean AFs were found between some species and between some PCB congeners. When all data were considered, the variability associated with AFs was lower than that found for bioaccumulation factors on a wet weight basis, indicating the utility of lipid and organic carbon normalization.
TL;DR: In this second dietary study, concentration—response relations were observed in both dietary treatments between the dietary concentrations of selenium and all three characteristics — fish growth, whole-body concentrations of Seenium and survival in seawater.
Abstract: The toxicity of two organoselenium diets was evaluated in 90- to 120-d partial life cycle tests with two life stages of chinook salmon (Oncorhynchus tshawytscha Walbaum) One of the diets contained fish meal made from high-selenium mosquitofish (Gambusia affinis Baird and Girard) collected from the selenium-laden San Luis Drain, California (here termed SLD diet) and the other contained meal made from low-selenium mosquitofish (collected from a reference site) fortified with selenomethionine A 90-d study was conducted with swim-up larvae in a water-simulating dilution of San Luis Drain water in a standardized fresh water; and a 120-d study was conducted with fingerlings 70-mm long in a water of similar quality but prepared with a standardized brackish water After 90 d of exposure in the freshwater study, survival was reduced in fish fed ≥96 μg Se/g of either diet, and growth was reduced in fish fed ≥53 μg Se/g of SLD diet or ≥182 μg Se/g of selenomethionine diet Reduced fish growth, whole-body concentrations of selenium and survival were strongly correlated to concentrations of selenium in both diets After 120 d of exposure in the brackish-water study, survival was unaffected but growth was reduced in fish fed ≥182 μg Se/g of SLD diet or 354 μg Se/g of selenomethionine diet After 120 d of dietary exposure, survival during a 10-d seawater challenge test was reduced in fish fed 354 μg Se/g of either diet In this second dietary study, concentration—response relations were observed in both dietary treatments between the dietary concentrations of selenium and all three characteristics — fish growth, whole-body concentrations of selenium and survival in seawater
TL;DR: Information has become available from three independent epidemiological studies indicating that methylmercury levels in the mother during pregnancy predict the probability of adverse effects in her offspring, which takes the form of psychomotor retardation.
Abstract: Human health risks from methylmercury in fish are evaluated in terms of dose-response relationships for both adult and prenatal human exposures Specifically, information has become available from three independent epidemiological studies indicating that methylmercury levels in the mother during pregnancy predict the probability of adverse effects in her offspring The mercury levels in the mother are measured as concentration in head hair which in turn is an excellent predictor of blood concentration The adverse effects in the offspring take the form of psychomotor retardation These dose-response relations along with a one-compartment kinetic model for methylmercury accumulation in humans will be used to estimate minimum toxic daily intakes; these are, for nonpregnant adults, 4,300 ng Hg/kg body weight/d and about 600 to 1,100 ng Hg/kg/d for pregnant adults These values assume continuous exposure until the individual has attained steady state balance with respect to the body burden of methylmercury This will take up to one year in most cases
TL;DR: The effects of dissolved organic matter (DOM) on the transport of hydrophobic organic compounds in soil columns were investigated in this article, where three compounds (naphthalene, phenanthrene and DDT) that spanned three orders of magnitude in water solubility were used.
Abstract: The effects of dissolved organic matter (DOM) on the transport of hydrophobic organic compounds in soil columns were investigated. Three compounds (naphthalene, phenanthrene and DDT) that spanned three orders of magnitude in water solubility were used. Instead of humic matter, molecularly well-defined DOM represented by Triton X-100, a nonionic industrial detergent, and bovine serum albumin protein were used. In batch isotherm studies, the sorption of naphthalene to both model DOMs appeared to be hydrophobic in nature and quantitatively similar to the binding to humic materials. Equations were derived to model the enhanced transport of organic compounds by DOM based on octanol/water partition coefficients, Kow. For a specific soil and DOM level, it was shown theoretically and experimentally that all organic compounds with Kow values above a specific value should move at the same rate in ground water. In some situations, DOM can increase the movement of highly hydrophobic compounds, such as DDT, by a factor of a thousand or more. This enhanced transport in the presence of DOM can either be a problem, as with ground water contaminant spreading, or a benefit, as with contaminated aquifer cleanup.
TL;DR: In this paper, the authors investigated the mechanism of formation and release of highly immobilized residues of some small nonpolar halogenated hydrocarbons in two surface soils, a stream sediment and an aquifer sediment.
Abstract: The mechanism of formation and release of highly immobilized residues of some small nonpolar halogenated hydrocarbons in two surface soils, a stream sediment and an aquifer sediment was investigated. The labile sorbed fractions of compound were removed from treated soils by purging to infinite dilution in aqueous suspensions for 96 h. The remaining slowly reversible (residual) fraction of compound in the soil was quantitated as a function of prepurge sorption conditions. The residual increased nonlinearly with sorption equilibration time and applied concentration. Residuals in whole soils and whole soils pretreated with H2O2 were correlated with soil organic carbon. Among wet-sieved particle size fractions, however, the organic carbon-based concentrations followed the order, sand > silt >> clay. Also, some residual was associated with undecomposed plant matter. Release of the residual into water was greatly increased by pulverization of the soil and by acidification of the soil suspension. The results indicate that the slow release of the residual fraction is caused by molecular diffusion from remote sites in the soil organic matter matrix. Mineral surface and clay interlayer adsorption were ruled out by the finding of low residuals in the clay-sized particles. However, the mineral fraction plays an important role by shielding some of the organic matter in interstitial pores of particle aggregates from equilibrium with bulk solution.
TL;DR: In this paper, the authors studied relations between lacustrine characteristics and the total mercury (Hg) content of calendar age-2 yellow perch (Perca flavescens) in 10 seepage lakes in north-central Wisconsin.
Abstract: We studied relations between lacustrine characteristics and the total mercury (Hg) content of calendar age-2 yellow perch (Perca flavescens) in 10 seepage lakes in north-central Wisconsin. Mean concentrations and burdens (masses) of Hg in whole perch varied widely among lakes, were negatively correlated with lake pH and were positively correlated with total Hg concentration in surficial profundal sediment. Approximately 80 to 90% of the variation in Hg concentration and burden in whole perch was explained with multiple regressions containing two independent variables: either lake pH or alkalinity, and Hg concentration in surficial sediment. Variation among lakes in the Hg concentration in yellow perch was unrelated to their relative rates of growth. The mean concentration of Hg in axial muscle tissue of age-5 walleyes (Stizostedion vitreum vitreum) from five of the study lakes was highly correlated with the mean concentration in whole age-2 perch in the same lakes. We hypothesized that the high Hg concentrations often seen in piscivorous fish in low-alkalinity lakes (relative to high-alkalinity lakes) is at least partly due to a greater dietary intake of Hg in such waters. Furthermore, the analysis of small yellow perch—the preferred prey of adult walleyes and an important forage species for many predatory fishes in the north-central United States—may be an effective approach to assessing Hg bioavailability in the region's lakes.
TL;DR: The concentration of mercury in precipitation and in streams of a central Ontario lake were measured over a one year period as mentioned in this paper, and the concentrations in streams were generally very low (<5 ng/L), but during warm periods with low discharge, concentrations often exceeded 20 n/L in a headwater stream draining a wetland.
Abstract: The concentration of mercury in precipitation and in streams of a central Ontario lake were measured over a one year period. The concentrations in streams were generally very low (<5 ng/L), but during warm periods with low discharge, concentrations often exceeded 20 ng/L in a headwater stream draining a wetland. The concentration in precipitation varied from about 2 to nearly 30 ng/L and exhibited no seasonal pattern. By combining the concentration data with discharge and precipitation depth the inputs of mercury from runoff and direct deposition were estimated. Direct wet deposition accounted for over half of the supply of mercury to the lake. The watersheds retained most of the mercury deposited on them. The presence of wetlands appeared to decrease retention efficiency.
TL;DR: The relatively high theoretical PAH flux through the food chain did not result in increasing concentrations with increasing trophic level, which indicates that PAHs are biotransformed quite fast, however, many intermediate metabolites ofPAHs have a mutagenic and carcinogenic potential, which makes it important to observe these compounds when assessing ecotoxicological risks.
Abstract: This in situ study is focusing on the distribution, biotransformation and flux of 19 polycyclic aromatic hydrocarbons (PAH19) in the food chain seston-blue mussel (Mytilus edulis L)-common eider duck (Somateria mollissiima L) as well as the distribution in the gallbladder, liver, adipose tissue and egg of the duck All samples were collected within the open northern Baltic proper coastal areas Analyses were carried out by gas chromatography/mass spectrometry with electron impact (GC-MSEI) and negative ion chemical ionization (GC-MSNICI) With a multivariate statistical method (SIMCA) a significant change in the PAH composition through the food chain was found This change probably depends on an increasing metabolic activity with increasing trophic level, due to a selective biotransformation capacity for different PAHs Decreasing PAH concentrations with increasing trophic level were found The PAH concentrations in the different eider duck organs were: gallbladder > adipose tissue ≥ liver The theoretical inhalation of air-dispersed PAHs was of no significance compared to the exposure from food The relatively high theoretical PAH flux through the food chain did not result in increasing concentrations with increasing trophic level, which indicates that PAHs are biotransformed quite fast However, many intermediate metabolites of PAHs have a mutagenic and carcinogenic potential, which makes it important to observe these compounds when assessing ecotoxicological risks
TL;DR: It is concluded that variation in lipid can account for much variation in tolerance in a subpopulation of similarly sized individuals and that the fattest survives the longest for similarly exposed organisms.
Abstract: It is concluded that variation in lipid can account for much variation in tolerance in a subpopulation of similarly sized individuals; that gill morphology is another variable influencing toxic response; and that, in general, for similarly exposed organisms, the fattest survives the longest
TL;DR: This sediment-contact bioassays appears to be more sensitive to hydrophobic contaminants such as a polychlorinated biphenyl than the standard sediment elutriate test with Microtox® bioassay.
Abstract: A new, rapid test is reported for the toxicity screening of sediments using inhibition of Photobacterium phosphoreum. The bacteria are placed in direct contact with the sediment and the change in luminescence of the Photobacterium is used to determine the toxicity of the sediment relative to a control site. This sediment-contact bioassay appears to be more sensitive to hydrophobic contaminants such as a polychlorinated biphenyl than the standard sediment elutriate test with Microtox® bioassay.
TL;DR: In this article, Congener-specific analyses of the PCBs in Acushnet Estuary (New Bedford, MA) sediments and waters were undertaken to identify the PCB alteration and transport processes occurring in coastal marine sediments.
Abstract: Congener-specific analyses of the PCBs in Acushnet Estuary (New Bedford, MA) sediments and waters were undertaken to identify the PCB alteration and transport processes occurring in coastal marine sediments. These analyses indicated that (a) the PCBs deposited at the sediment sites sampled had originally consisted of Aroclors 1242 and 1254, in widely varying proportions; (b) these PCBs had undergone vertical movement within the sediments, rather than remaining stratified, but not horizontal translocation between sites; (c) they had also undergone extraction into the water, albeit at declining rates, with some consequent changes in composition but (d) the major compositional change was caused by a previously unreported type of reductive dechlorination process, designated Process H. This presumably anaerobic microbial process, subsequently identified at several other locations as well, had selectively removed non-ortho chlorines from most of the higher PCB congeners, especially those associated with acute toxic effects. It appeared to have begun near the upper end of the estuary and not yet reached its lower portions, thus providing a marker for tracing the origin of the PCBs in estuarine water samples.
TL;DR: Waterborne xenobiotics enter fish and other aquatic species primarily by transfer across the gill epithelium, where uptake may be controlled by transfer to storage tissues, e.g., by blood flow to adipose tissue.
Abstract: Waterborne xenobiotics enter fish and other aquatic species primarily by transfer across the gill epithelium. Potential barriers to uptake include water flow across the gill, diffusion across the gill epithelium and the overlying aqueous stagnant layer and blood flow through the gill (cardiac output). In general, for any particular chemical, only one of the barriers is operative with the resistance offered by the others being negligible. The rate-limiting barrier is determined by the physico- and biochemical properties of the substance: molecular size, lipophilicity, binding to blood proteins and formed elements. The resistance of each barrier is affected differently by variables such as temperature, molecular size, lipophilicity and body size of the animal. When the resistance offered by the gill barriers is low, uptake may be controlled by transfer to storage tissues, e.g., by blood flow to adipose tissue.
TL;DR: In this paper, the linear alkyl benzene sulfonate (LAS) is extensively removed by sewage treatment with resulting river water concentrations in the low ppb range.
Abstract: Results from extensive monitoring from 1973 to 1986 indicate that linear alkyl benzene sulfonate (LAS) is extensively removed by sewage treatment with resulting river water concentrations in the low ppb range. Wastewater treatment plant removal efficiencies exceed those for biochemical oxygen demand (BOD); they average 98% for activated sludge, 80% for trickling filters and 27% for primary clarification. Concentrations in influent sewage (x = 3.5 mg/L), effluent sewage (x = 0.06–2.1 mg/L), and in river waters (<0.005–0.3 mg/L) are in agreement with predicted concentrations and measurements by other investigators. Levels of LAS in soil cores analyzed shortly after sludge amendment range from <3 to 47 mg/kg and are consistent with sludge loading rates and biodegradation of LAS from the previous year's sludge application. Removal of LAS occurs by biodegradation in all compartments and sorption/settling from the water column. Longer chain length, more sorptive LAS homologs are relatively enriched in sludge solids and in river sediments, thus the average LAS chain length was found to be higher in those compartments. Results obtained from long-term monitoring support the rapid removal of LAS by biodegradation in the environment.
TL;DR: Based on lethality, H. limbata was the most sensitive organism to the toxicity of Detroit River sediment, and the dose-response relationship derived from each technique needs to be interpreted accordingly.
Abstract: The relative sensitivities of bioassays to determine the toxicity of sediments were investigated and three methods of making the sample dilutions required to generate dose-response relationships were compared. The assays studied were: (a) Microtox®, a 15-min assay of Photobacterium phosphoreum bioluminescence inhibition by pore water; (b) 48-h Daphnia magna lethality test in pore water; (c) 10-d subchronic assay of lethality to and reduction of weight gain by Chironomus tentans performed in either whole sediment or pore water; (d) 168-h acute lethality assay of Hexagenia limbata in either whole sediment or pore water. The three methods of diluting sediments were: (a) extracting pore water from the toxic location and dilution with pore water from the control station; (b) diluting whole sediment from the toxic location with control whole sediment from a reference location, then extracting pore water; and (c) diluting toxic, whole sediment with whole sediment from a reference location, then using the whole sediment in bioassays. Based on lethality, H. limbata was the most sensitive organism to the toxicity of Detroit River sediment. Lethality of D. magna in pore water was similar to that of H. limbata in whole sediment and can be used to predict effects of whole sediment toxicity to H. limbata. The concentration required to cause a 50% reduction in C. tentans growth (10-d EC50) was approximately that which caused 50% lethality of D. magna (48-h LC50) and was similar to the toxicity that restricts benthic invertebrate colonization of contaminated sediments. While the three dilution techniques gave similar results with some assays, they gave very different results in other assays. The dose-response relationships determined by the three dilution techniques would be expected to vary with sediment, toxicant and bioassay type, and the dose-response relationship derived from each technique needs to be interpreted accordingly.
TL;DR: In this article, a study of new and weathered utility lumber pressure-treated with chromated copper arsenate (CCA) was carried out by atomic absorption spectroscopy.
Abstract: Samples of new and weathered utility lumber pressure-treated with chromated copper arsenate (CCA) were tested for leaching of copper, chromium and arsenic by submersion in leaching baths of various pH levels. Accumulation of metals was monitored in leachate at pH 3.5, 4.5, 5.5, 7.0 and 8.5 over a period of 40 d by atomic absorption spectroscopy. Copper, chromium and arsenic were found in the leachate of both new and weathered wood with significantly higher levels of all metals occurring at acidic pH levels. Up to 100% of CCA treatment metals were found to have leached at pH 3.5, whereas a maximum of 9% of metals leached at pH 8.5. Metal leaching was found to be higher in citric acid than in dilute sulfuric acid solutions. Leaching of copper, chromium and arsenic was not proportional to the amount of metal present before leaching.
TL;DR: In this paper, the authors studied the partitioning of mercury (Hg) among air, water, sediments and fish at Little Rock Lake, a clear water seepage lake in north-central Wisconsin.
Abstract: We studied the partitioning of mercury (Hg) among air, water, sediments and fish at Little Rock Lake, a clear water seepage lake in north-central Wisconsin. The lake was divided with a sea curtain into two basins, one acidified with sulfuric acid to pH 5.6 for two years and the other an untreated reference site (mean pH 6.1), to document the effects of acidification. Trace-metal-free protocols were used to measure Hg at the picomolar level in air and water. Total gaseous Hg in air samples averaged 2.0 ng/m3. Total Hg in unfiltered water samples collected in 1986 after the fall overturn averaged about 1 ng/L in the acidified and reference basins. Mercury in surficial sediments was strongly correlated with volatile matter content and ranged from 10 to about 170 ng/g (dry weight) in both basins. Total Hg concentrations in whole, calendar age-1 yellow perch (Perca flavescens), sampled after one year of residence in the lake, averaged 114 ng/g (fresh weight) in the reference basin and 135 ng/g in the acidified basin – a highly significant (p < 0.01) difference. The mean whole-body burden (quantity) of Hg in age-1 perch did not differ between basins after the first year, but was significantly greater in the treatment basin than in the reference basin after the second year of acidification. Differences between the two basins in the bioaccumulation of Hg were attributed to internal (within-lake) processes that influence the bioavailability of the metal. An initial Hg budget for the treatment basin of Little Rock Lake showed that atmospheric deposition and sedimentary remobilization of Hg are potentially important processes influencing its biogeochemical cycling and uptake by fish.
TL;DR: The acute toxicities of four recently developed pyrethroid insecticides were experimentally compared to the acute toxicity of a first generation pyrethroids, in static-flow, 48-h bioassays with Daphnia magna and Ceriodaphnia dubia.
Abstract: The acute toxicities of four recently developed pyrethroid insecticides (bifenthrin, cyfluthrin, lambda cyhalothrin and tralomethrin) were experimentally compared to the acute toxicity of a first generation pyrethroid (permethrin), in static-flow, 48-h bioassays with Daphnia magna and Ceriodaphnia dubia. The four new generation pyrethroids exhibited greater toxicity, with LC50s ranging from 0.15 to 1.04 μg/L for D. magna and 0.07 to 0.30 μg/L for C. dubia, in comparison to permethrin with LC50s of 1.25 μg/L for D. magna and 0.55 μg/L for C. dubia. Tralomethrin and cyfluthrin were most toxic to D. magna, with LC50s of 0.15 and 0.17 μg/L, respectively. C. dubia exhibited the greatest sensitivity to the pyrethroids, with an LC50 of 0.07 μg/L for bifenthrin. C. dubia was equally or more sensitive than D. magna to all of the insecticides.
TL;DR: The relative sensitivity, analytical precision, discriminatory power and concordance among endpoints and with sediment chemistry were compared among five sediment toxicity tests.
Abstract: The relative sensitivity, analytical precision, discriminatory power and concordance among endpoints and with sediment chemistry were compared among five sediment toxicity tests. The tests were performed with aliquots of 15 composited, homogenized sediment samples. Survival and a variety of sublethal endpoints were determined in tests performed with the amphipods Rhepoxynius abronius and Ampelisca abdita, embryos of the mussel Mytilus edulis, embryos of the urchin Strongylocentrotus purpuratus, and the polychaete Dinophilus gyrociliatus. Each sample was also tested for trace metal and organic compound concentrations, organic carbon content and texture. Two of the five tests (survival among M. edulis and survival among R. abronius) were highly sensitive to the samples and had relatively high precision, but the results were correlated most highly with sedimentological variables. One of the tests (survival among A. abdita) was relatively insensitive, but the results were highly correlated with only the concentrations of toxic chemicals. The test with S. purpuratus indicated mutagenicity in several samples that had high hydrocarbon concentrations. The test of pore water with D. gyrociliatus was intermediate in sensitivity and precision and not correlated highly with the results from the other tests.
TL;DR: In this article, the uptake of sediment-associated hexachlorobenzene (HCB) by the deposit-feeding clam Macoma nasuta (Conrad) was determined using a clam ventilation chamber.
Abstract: The uptake of sediment-associated hexachlorobenzene (HCB) by the deposit-feeding clam Macoma nasuta (Conrad) was determined using a clam ventilation chamber. Clams were exposed to [14C]HCB-dosed sediment, and the 14C amounts were measured in inhalant and exhalant waters, fecal pellets and soft tissues. The volume of water the clam ventilated and the amount of fecal pellets produced were measured. The contributions of 10 possible uptake routes to HCB tissue residues were estimated using a bioenergetic-based bioaccumulation model. Mass balance results indicate that uptake of HCB by the gut from ingested solids was the single most important route, accounting for 63 to 84% of HCB tissue residues. The next largest route was uptake from interstitial water ventilated across the gills, which accounted for 11 to 12% of tissue residues. Uptake of HCB from overlying water was minimal. These results indicate that sediment-bound HCB is bioavailable to benthic deposit feeders such as Macoma and supports the contention that ingested sediment is an important uptake route for highly lipophilic pollutants.