Influence of soil properties on copper toxicity for two soil invertebrates

Although a large body of evidence indicates that metal toxicity to soil organisms is affected by physicochemical soil properties, use of this knowledge in ecological risk assessments is limited because of the lack of a model applicable to a wide range of soils. To study the effect of soil characteristics on the toxicity of copper to terrestrial invertebrates, chronic toxicity tests with Eisenia fetida and Folsomia candida were performed in 19 European field soils. These soils were carefully selected to cover the range of toxicity-influencing parameters encountered in the European Union. Toxicity values varied greatly among soils, with 28-d median effect concentrations ranging from 72.0 to 781 mg Cu/kg dry weight for E. fetida and from 45.4 to 2,270 mg Cu/kg dry weight for F. candida. For both species, variation in copper toxicity values was best explained by differences in the actual cation-exchange capacity (CEC) at soil pH. Using the obtained regression algorithms, the observed toxicity could, in most cases, be predicted within a factor of two for E. fetida and within a factor of three for F. candida. The developed models were validated in three additional European field soils, a standard artificial soil and a standard field soil. The presented regression equations, based on the actual CEC, offer an easy-to-apply method for taking the influence of soil properties on metal toxicity into account.     

Increased alanine concentration is associated with exposure to fenitrothion but not carbamates in Chironomus riparius larvae

The polychlorinated insecticide toxaphene belonged to the most used pesticides in the 20th century. Even recently, significant residues have been found in soils at various sites in the world. However, knowledge on toxicity to soil organisms is limited. In this study, the effects of toxaphene on soil invertebrates Folsomia candida, Eisenia fetida, Enchytraeus albidus, Enchytraeus crypticus, Caenorhabditis elegans, and microorganisms were investigated. Among the organisms tested, F. candida was the most sensitive. The 50% effect on survival and reproduction output (LC50 and EC50) was found at concentrations of 10.4 and 3.6 mg/kg, respectively. Sensitivity of other organisms was significantly lower with effective concentrations at tens or hundreds of mg/kg. Our data on soil toxicity were recalculated to soil pore-water concentrations and good accordance with available data reported for aquatic toxicity was found. Since soil concentrations at some sites are comparable to concentrations effective in our tests, toxaphene may negatively affect soil communities at these sites.     

Effects of short-chain chlorinated paraffins on soil organisms

Despite the fact that chlorinated paraffins have been produced in relatively large amounts, and high concentrations have been found in sewage sludge applied to soils, there is little information on their concentrations in soils and the effect on soil organisms. The aim of this study was to investigate the toxicity of chlorinated paraffins in soils. The effects of short-chain chlorinated paraffins (64% chlorine content) on invertebrates (Eisenia fetida, Folsomia candida, Enchytraeus albidus, Enchytraeus crypticus, Caenorhabditis elegans) and substrate-induced respiration of indigenous microorganisms were studied. Differences were found in the sensitivity of the tested organisms to short-chain chlorinated paraffins. F. candida was identified as the most sensitive organism with LC(50) and EC(50) values of 5733 and 1230 mg/kg, respectively. Toxicity results were compared with available studies and the predicted no effect concentration (PNEC) of 5.28 mg/kg was estimated for the soil environment, based on our data.     

Effect of soil properties and aging on the toxicity of copper for Enchytraeus albidus, Enchytraeus luxuriosus, and Folsomia candida

In the present study, the effect of the heavy-metal salt copper chloride (CuCl2.2H2O) in soils freshly spiked (3 d) and aged (70 +/- 10 d; mean +/- SD) was studied in the test species Enchytraeus albidus, E. luxuriosus, and Folsomia candida. Up to nine soils were used: Besides the Organisation for Economic Co-operation and Development (OECD) artificial soil and the Agricultural Testing and Research Agency (Landwirtschaftliche Untersuchungs- und Forschungsanstalt, Speyer, Germany) 2.2 natural standard soils, the others were selected based on the EURO Soil approach, taking into account the effect of different soil parameters (pH, organic matter, grain size distribution, and carbon to nitrogen ratio). Additionally, the effect of the chloride ions was studied separately. The results revealed the following: First, a soil effect was observed; for example, in F. candida, median effective concentrations (EC50s) varied between 262 mg/kg in a sample from the same site as the original EURO Soil 5 soil and greater than 1,000 mg/kg in OECD soil. Second, an aging effect was observed, mainly in F. candida. For example, toxicity of offspring survival was increased twofold in the OECD soil and approximately eightfold with aging in the EURO Soil 7 soil, whereas the enchytraeid species did not react differently after aging. Third, an effect of chloride ions on reproduction of the animals was found; however, this effect was independent of the aging period. Fourth, species variation was seen in terms of sensitivity (EC50), decreasing in the following order: E. luxuriosus > E. albidus > F. candida. Differences in toxicity of offspring survival between enchytraeids and F. candida might be explained by the different routes of uptake.     

Toxicity of sodium tungstate to earthworm, oat, radish, and lettuce

Due to unknown effects of the potential exposure of the terrestrial environment to tungsten substances, a series of toxicity studies of sodium tungstate (Na(2) WO(4) ) was conducted. The effect on earthworm (Eisenia fetida) survival and reproduction was examined using Organisation for Economic Co-operation and Development (OECD) Guideline 222. No effect on either endpoint was seen at the highest concentration tested, resulting in a 56-d no-observed-effect concentration (NOEC) of ≥586 mg tungsten/kg dry soil (nominal concentrations). The effect of sodium tungstate on emergence and growth of plant species was examined according to OECD Guideline 208: oat (Avena sativa), radish (Raphanus sativus), and lettuce (Lactuca sativa). No effects on emergence, shoot height, and dry shoot weight were observed in oats exposed to the highest concentration, resulting in a 21-d NOEC of ≥586 mg tungsten/kg dry soil. The NOECs for radish and lettuce were 65 and 21.7 mg tungsten/kg dry soil (nominal concentrations), respectively. Respective 21-d median effective concentration values (EC50) for radish and lettuce were >586 and 313 mg tungsten/kg dry soil (based on shoot height) (confidence level [CL] -8.5-615); EC25 values were 152 (CL 0-331) and 55 (CL 0-114) mg tungsten/kg dry soil. Results are consistent with the few other tungsten substance terrestrial toxicity studies in the literature.     

Modeling zinc toxicity for terrestrial invertebrates

Acute and chronic ecotoxicity tests with zinc were performed with the earthworm Eisenia fetida, the potworm Enchytraeus albidus, and the springtail Folsomia candida. To assess the influence of the soil type on zinc toxicity for these soil invertebrates, these tests were carried out in a standard artificial soil, a sandy and a loamy field soil. Based on the results of this experimental work and data taken from literature, models were developed relating the ecotoxicity of zinc to the most important parameters controlling bioavailability: pH and cation exchange capacity. Models were developed for E. fetida and F. candida using the regression technique partial least squares projection to latent structures (PLS). Acute as well as chronic toxicity data of both organisms could be normalized on the basis of the pH and the cation exchange capacity of the test soils. For other terrestrial invertebrates, not enough data were available to develop reliable models.     

Toxicity and bioaccumulation of phenanthrene in Enchytraeus albidus (Oligochaeta: Enchytraeidae)

Polycyclic aromatic compounds, such as phenanthrene (PHE), tend to accumulate in the soil compartment, where they may be retained for many years because of their persistency and hydrophobicity. The toxicity and bioaccumulation of these chemicals in soil biota and potential biomagnification along the food chain is an issue of concern. The main goal of this study was to determine the toxicity and bioaccumulation of PHE in Enchytraeus albidus (Oligochaeta: Enchytraeidae) in a natural standard soil (LUFA 2.2) following standard test guidelines. Phenanthrene dose-relatedly affected the survival and reproduction of E. albidus with median lethal concentration and median effective concentration (EC50) values of 135 and 33?mg/kg dry soil, respectively. A toxicokinetics study, performed at a nontoxic soil concentration of 8?mg/kg, showed uptake and elimination rate constants of 4.91?kg soil per kilogram fresh weight animal per day and 0.236 per day, respectively and a bioaccumulation factor (BAF) of 20.8?kg soil per kilogram fresh weight animal. These results show that the three-week exposure in the toxicity test with E. albidus is sufficiently long to reach equilibrium, but also that PHE may accumulate to considerable levels, possibly causing a risk for predators.     

Manganese toxicity in soil for Eisenia fetida, Enchytraeus crypticus (Oligochaeta), and Folsomia candida (Collembola)

The U.S. Environmental Protection Agency is developing Ecological Soil Screening Level (Eco-SSL) benchmarks for ecological risk assessment (ERA) of contaminants at Superfund sites. Eco-SSLs are developed from published values whenever sufficient quantity and quality of data exist. Because insufficient information was available to generate an Eco-SSL for Mn, standardized toxicity testing was undertaken to fill the data gaps. Tests included the earthworm (Eisenia fetida) cocoon production test, the enchytraeid (Enchytraeus crypticus) reproduction test, and the collembolan (Folsomia candida) reproduction test, all conducted in Sassafras sandy loam soil that supports a relatively high bioavailability of metals. Weathering and aging of manganese-amended soil were carried out to more closely simulate exposure effects at Superfund sites on soil invertebrates. Data were analyzed by nonlinear regression to determine EC20 and EC50 values based on concentration-response relationships. The toxicity order for manganese in Sassafras sandy loam was E. crypticus>E. fetida>F. candida, with EC20 values of 116, 629, and 1209 mg kg(-1), respectively. The Eco-SSL requirement for the testing of multiple representative species is well justified. All study results will be submitted to the Eco-SSL Task Group for quality control review prior to inclusion in the Eco-SSL database.     

Toxicity of chromium(III) and chromium(VI) to the earthworm Eisenia fetida

The effects of Cr(III) and Cr(VI) on the survival, behavior, and morphology of the earthworm, Eisenia fetida, in water at pH 6, 7, and 8 and their toxicity in 10 different soils and an organic substrate have been assessed. A decrease in the pH of water resulted in increased toxicity of Cr to the earthworm. In water, both Cr species produced behavioral changes and morphological symptoms. The 48-h LC(50) values of Cr(III) at pH 6, 7, and 8 were 1.93, 2.55, and 2.78 mg/L, and those of Cr(VI) were 0.47, 0.61, and 0.63 mg/L, respectively. The 14-day median lethal concentrations (LC(50)) of Cr(III) and Cr(VI) for earthworm range from 1656 to 1902 mg/kg for Cr(III) and from 222 to 257 mg/kg for Cr(VI) in soil. In the organic substrate, the LC(50) values of Cr(III) and Cr(VI) were 1635 and 219 mg/kg, respectively. Stepwise multiple regression analysis predicted that clay content of soils accounted for 92% and 88% of the variation in the LC(50) values of Cr(III) and Cr(VI), respectively.     

Ecotoxicity of a polycyclic aromatic hydrocarbon (PAH)-contaminated soil

Soil samples from a former cokery site polluted with polycyclic aromatic hydrocarbons (PAHs) were assessed for their toxicity to terrestrial and aquatic organisms and for their mutagenicity. The total concentration of the 16 PAHs listed as priority pollutants by the US Environmental Protection Agency (US-EPA) was 2634+/-241 mg/kgdw in soil samples. The toxicity of water-extractable pollutants from the contaminated soil samples was evaluated using acute (Vibrio fischeri; Microtox test, Daphnia magna) and chronic (Pseudokirchneriella subcapitata, Ceriodaphnia dubia) bioassays and the EC values were expressed as percentage water extract in the test media (v/v). Algal growth (EC50-3d=2.4+/-0.2% of the water extracts) and reproduction of C. dubia (EC50-7d=4.3+/-0.6%) were the most severely affected, compared to bacterial luminescence (EC50-30 min=12+/-3%) and daphnid viability (EC50-48 h=30+/-3%). The Ames and Mutatox tests indicated mutagenicity of water extracts, while no response was found with the umu test. The toxicity of the soil samples was assessed on the survival and reproduction of earthworms (Eisenia fetida) and collembolae (Folsomia candida), and on the germination and growth of higher plants (Lactuca sativa L.: lettuce and Brassica chinensis J.: Chinese cabbage). The EC50 values were expressed as percentage contaminated soil in ISO soil test medium (weight per weight-w/w) and indicated severe effects on reproduction of the collembola F. candida (EC50-28 d=5.7%) and the earthworm E. fetida (EC50-28 d=18% and EC50-56 d=8%, based on cocoon and juvenile production, respectively). Survival of collembolae was already affected at a low concentration of the contaminated soil (EC50-28 d=11%). The viability of juvenile earthworms was inhibited at much lower concentrations of the cokery soil (EC50-14 d=28%) than the viability of adults (EC50-14 d=74%). Only plant growth was inhibited (EC50-17d=26%) while germination was not. Chemical analyses of water extracts allowed us to identify inorganic water-extractable pollutants as responsible for toxicity on aquatic species, especially copper for effects on D. magna and C. dubia. The soil toxicity on collembolae and earthworms could be explained by 4 PAH congeners-fluorene, phenanthrene, pyrene, and fluoranthene. Yet, toxicity of the cokery soil as a whole was much lower than toxicity that could be deduced from the concentration of each congener in spiked soils, indicating that pollutants in the soil became less bioavailable with ageing.     

Growth and reproduction of the earthworm Eisenia fetida after exposure to leachate from wood preservatives

Wood preserved with chromated copper arsenate (CCA) and alkaline copper quaternary (ACQ) was mixed with artificial rainwater, to generate leachates containing As, Cr and Cu. Then, leachates were applied to two soils at rates of 13-169 mg As kg(-1) soil (dry weight basis), 12-151 mg Cr kg(-1) and 10-216 mg Cu kg(-1). Metal bioavailability was evaluated after 28 days using the earthworm Eisenia fetida (Savigny). Metal concentrations in earthworm tissue ranged from negligible to 80 mg As kg(-1) (dry weight basis), 89 mg Cr kg(-1) and 90 mg Cu kg(-1), which appeared to be non-lethal to E. fetida. There was less Cu available to earthworms in the Courval soil (pH 7.8) than the Chateauguay soil (pH 6.8), but earthworm growth and reproduction were not affected by exposure to Cu from ACQ-treated wood. In contrast, earthworms exposed to As, Cr and Cu from the CCA-treated wood gained weight more quickly in the Courval soil (1.3-21 mg g(-1) initial biomass days) than in the Chateauguay soil (0.2-7.8 mg g(-1) day(-1)), but fewer than 20% of the cocoons deposited by the faster-growing earthworms hatched by the end of the 56 days ecotoxicology test. It appeared that E. fetida can allocate more energy to growth than reproduction, delaying cocoon development and hatching in some situations. Further information is needed on the soil factors that may induce such behavior, as it can affect the interpretation of results from the earthworm ecotoxicology test.     

Uptake and toxicity of spiked nickel to earthworm Eisenia fetida in a range of Chinese soils

Bioavailability and toxicity of metals to soil organisms varies among different soils, and knowledge of this variance is useful for the development of soil environmental quality guidelines. In the present study, laboratory experiments were performed to investigate the effects of variations in nickel (Ni) uptake and toxicity on growth, cocoon output, and juvenile production in the earthworm Eisenia fetida in 13 Chinese soils spiked with nickel chloride. Body weight development of E. fetida was rather insensitive to Ni, and significant inhibition of growth was observed only at high Ni concentrations, such as 560 and 1000 mg/kg. The 50% inhibition effect concentrations (EC50s) for cocoon and juvenile production, based on measured Ni concentrations in soils, varied from 169 to 684 mg/kg and from 159 to 350 mg/kg, respectively. The EC50s represented approximately fourfold variation for cocoon output and twofold variation for juvenile production among 13 Chinese soils. Juvenile production, compared to cocoon output, was a more sensitive endpoint parameter to Ni. Nickel uptake in E. fetida increased as simple linear functions of increasing soil Ni concentrations. Tissue Ni-based EC50s (based on Ni concentrations in earthworm tissues) for cocoon production varied from 37 to 121 mg/kg (threefold variation) in 12 of 13 soils, suggesting a similar variation to that of soil Ni-based EC50s. Relationship analysis between soil properties and Ni toxicity showed that neither the EC50s for cocoon output nor those for juvenile production presented significant correlation with soil properties (pH, organic matter content, cation exchange capacity, clay content, Ca2? and Mg2?). This may be ascribed to the narrow range of properties of selected soils. The soil factors that determined Ni toxicity to earthworm reproduction remain undetermined in the present study, and these data should be used cautiously when developing toxicity prediction models because of the narrow selection of soil properties.     

Effects of insect growth regulators on the nontarget soil arthropod Folsomia candida (Collembola)

The aim of this study was to assess the effect of several insect growth regulators (IGRs) on the nontarget soil arthropod Folsomia candida (Collembola). The survival and reproduction rates of F. candida were evaluated after 28 days of exposure to six IGRs (methoprene, fenoxycarb, precocene II, tebufenozide, hexaflumuron and teflubenzuron) and to one herbicide (diuron) in artificial soil. The differences in the sensitivity of F. candida to these different substances are high. The chitin synthesis inhibitors teflubenzuron and hexaflumuron were the most toxic compounds with an EC50 of 0.05 mg/kg (dry weight) for teflubenzuron and an EC50 of 0.6mg/kg for hexaflumuron. Teflubenzuron is toxic for F. candida at concentrations that are probably close to environmental levels of this insecticide. Inhibition of reproduction is strongly related to adult survival for the juvenile hormone agonist methoprene and for the antijuvenile hormone precocene II, with an EC50 of 173 mg/kg and a LC50 of 178mg/kg for methoprene and an EC50 of 15 mg/kg and a LC50 of 26 mg/kg for precocene II. Fenoxycarb, another juvenile hormone analog, showed a dose-response curve for mortality different from that of methoprene; at concentrations such as 3052 mg/kg no effect on adult survival was observed. However, the EC50 value of 113mg/kg is of the same order of magnitude as that obtained for methoprene. A test with compressed soil contaminated with fenoxycarb was conducted to observe parameters such as numbers of eggs laid and juveniles hatched. No differences were observed between these two endpoints for fenoxycarb. An EC50 of 109 mg/kg was obtained for the ecdysone agonist tebufenozide. The herbicide diuron showed a relatively high toxicity for F. candida with an EC50 of 20 mg/kg. Our results show that some of the tested IGRs can have effects on Collembola at environmentally relevant concentrations (toxicity/exposure ratios < 5 for teflubenzuron, hexaflumuron, and diuron).     

The effect of chromium on the hemoglobin concentration of Limnodrilus hoffmeisteri (Oligochaeta: Tubificidae)

The purpose of this study was to determine the toxic effects of polluted sediments, mainly chromium, the El Niagara reservoir (Aguascalientes, Mexico) on a benthic oligochaete species. Acute toxicity tests with hexavalent chromium in an artificial sediment-water system resulted in 24-, 48-, and 96-h LC50 values of 49.53, 22.81, and 5.11 mg available chromium/kg dry sediment, respectivley, in Limnodrilus hoffmeisteri. The uptake of chromium by tubificids from artificial and polluted reservoir sediments was found to increase with metal concentration in sediments and exposure time. The increase was higher in experiments with artificial sediment. Cr concentration in worms was related to hemoglobin content, which decreased significantly when Cr concentrations were above 1.0 microg/g dry weight. Bioavailable chromium in the El Niágara reservoir sediments may be an important factor limiting the benthic species in this ecosystem.     

Hexavalent chromium responsible for lung lesions induced by intratracheal instillation of chromium fumes in rats

Lung toxicity of chromium fumes (Cr fumes) was examined by a single intratracheal instillation into rats of 10.6 mg and 21.3 mg Cr fumes/kg body weight and by repeated (3 times) instillations of 10.8 mg and 21.7 mg Cr fumes/kg. The pathological changes were compared with those induced by single administrations of 3.2 mg and 19.2 mg Na2CO3 solution-insoluble fraction of Cr fumes (Cr-Fr)/kg and 20.8 mg commercially available chromium (III) oxide powder (Cr (III) oxide)/kg. Single and repeated administrations of Cr fumes suppressed growth rate in a dose-dependent manner, but administrations of Cr-Fr and Cr (III) oxide did not. A single administration of Cr fumes produced granulomas in the entire airways and alveoli with progressive fibrotic changes, as well as severe mobilization and destruction of macrophages and foamy cells. Those histopathological changes were aggravated by the repeated administration of Cr fumes. On the other hand, single administrations of Cr-Fr and Cr (III) oxide produced no remarkable histopathological changes. Cr fumes were found to be composed of 73.5% chromium (III) oxide and 26.5% chromium (VI) oxide. The primary particles of Cr fumes and Cr-Fr were similar, 0.02 micron in size (sigma g: 1.25), and Cr (III) oxide particles were 0.30 micron in size (sigma g: 1.53), measured by analytical electron microscopy (ATEM). Diffuse clusters of the primary particles in Cr fumes were identified as Cr (VI) oxide. The present results suggested that the lung toxicity of Cr fumes was mainly caused by these Cr (VI) oxide (CrO3) particles in Cr fumes.     

Reduction in acute toxicity of soils to terrestrial oligochaetes following the removal of bioavailable polycyclic aromatic hydrocarbons with mild supercritical carbon dioxide extraction

Three soil samples contaminated with polycyclic aromatic hydrocarbons (PAHs) that caused 100% mortality to terrestrial oligochaetes were extracted with supercritical carbon dioxide to remove the bioavailable fraction of PAHs. Although the remaining PAH concentrations were high after supercritical fluid extraction (SFE), 650 to 8,000 mg/kg, acute toxicity to Eisenia fetida and Enchytraeus albidus essentially was eliminated. These results demonstrate that mild SFE with pure carbon dioxide preferentially extracts PAH molecules that are bioavailable toxicologically to the oligochaetes, although biologically unavailable PAHs are not extracted, suggesting that SFE could be used for the removal of toxicity due to hydrophobic organic chemicals in soils during toxicity identification evaluations.     

Biochemical and spectroscopic studies of the response of Convolvulus arvensis L. to chromium(III) and chromium(VI) stress

The objective of the present study was to determine the oxidative stress caused by hexavalent chromium (Cr[VI]), the chromium (Cr) uptake, and the Cr speciation in Convolvulus arvensis L. plants grown in hydroponics media containing either Cr(VI) or Cr(III). The results demonstrated that C. arvensis plants exposed to Cr(VI) concentrations ranging from 0 to 40 mg/L expressed higher ascorbate peroxidase specific activity in roots than in shoots. On the other hand, catalase activity monitored in plants exposed to 2 mg/L of Cr(VI) for 24 h increased in roots after a few hours of exposure. However, catalase activity in shoots revealed a decrement almost immediately after treatment was initiated. The results from x-ray absorption spectroscopic studies indicated that the oxidation state of the supplied Cr(III) remained the same in plant tissues. The supplied Cr(VI), however, was reduced to the trivalent form in plant tissues. The results of inductively coupled plasma/optical emission spectroscopy demonstrated that after 5 d, the roots of plants exposed to 40 mg/L of Cr(III) or Cr(VI) accumulated approximately 25,000 and 3,500 mg/kg dry weight of Cr, respectively. Nevertheless, shoots concentrated 1,500 and 2,000 mg/kg dry weight of Cr from Cr(III) and Cr(VI), respectively, which indicated that Cr moved faster into C. arvensis plants when supplied as Cr(VI).     

Chromium Geochemistry and Bioaccumulation in Sediments from the Lower Hackensack River, New Jersey

Total and hexavalent chromium [Cr(VI)] were measured in sediment and sediment porewater in the lower Hackensack River (NJ) to assess the relationship between sediment geochemistry and chromium speciation, which in turn controls the mobility, bioavailability, and toxicity of chromium. Between 2003 and 2005, >100 surface (0 to 15 cm) sediment samples were tested for total chromium and Cr(VI), acid-volatile sulfides (AVS), ferrous iron (Fe(II)), divalent manganese (Mn(II)), ammonia, and organic carbon. Sediment porewater samples were collected by centrifugation or using in situ samplers colocated with the collection of sediments. In whole sediments, total chromium and Cr(VI) concentrations ranged from 5 to 9190 mg/kg dry weight (dw) and from <0.47 to 31 mg/kg dw, respectively. Sediment porewater concentrations ranged from <10 to 83 μg/l for total chromium; Cr(VI) was not detected in sediment porewater (n = 78). Concentrations of AVS (ranging between <10.6 to 4178 mg/kg) and other geochemistry measurements indicated anoxic, reducing conditions in the majority of sediment samples. In polychaetes (Nereis virens) and clams (Macoma nasuta) exposed in the laboratory for 28 days to sediments contained between 135 and 1780 mg/kg dw total chromium, concentrations in whole tissues after 24-hour depuration ranged between 1.2 and 14.8 mg/kg wet weight (ww; median 1.6 mg/kg ww) total chromium. In whole tissues of indigenous polychaetes collected from the sediment, tissue concentrations of total chromium ranged between 1.0 and 37.5 mg/kg ww (median = 2.1 mg/kg ww). Chromium concentrations in whole tissues of animals exposed in the field or in the laboratory showed no relationship with total chromium or Cr(VI) concentrations in the sediment. There were no statistical differences among animals exposed to sediments from site and reference locations. The results of this study are consistent with sediment studies conducted elsewhere indicating low chromium bioavailability in sediment under reducing conditions. This study also highlights the importance of sediment geochemistry and in situ porewater measurements to understand the ecological significance of chromium in sediment and the potential for human health and ecological exposures.     

Lethal and subchronic effects of 2,4,6-trinitrotoluene (TNT) on Enchytraeus albidus in spiked artificial soil

The effects of 2,4,6-trinitrotoluene (TNT) exposure in spiked artificial soil on the survival and reproduction rate of the white potworm Enchytraeus albidus were studied. Based on the initial concentrations, TNT in freshly spiked soil decreased enchytraeid survival (21-day LC(50)=422+/-63 (SD)mg/kg, N=3) and fecundity (42-day EC(50)=111+/-34, N=4). Data also indicated that TNT was 5-10 times more lethal to juveniles than adults, and lethality was less pronounced in TNT-spiked soils aged for 21 days. A time-dependent decrease in the TNT concentrations, as well as a concomitant increase in the levels of 2- and 4-aminodinitrotoluene, was observed during the 42-day toxicity test. Taken together, TNT (or one of its metabolites) is more lethal to juvenile than adult enchytraeids. This effect may explain, at least in part, the ability of TNT to decrease fecundity as determined using the enchytraeid mortality-reproduction test.     

Studies and evaluation of the potential toxicity of decabromodiphenyl ethane to five aquatic and sediment organisms

The potential toxicity of decabromodiphenyl ethane (DBDP-Ethane) was explored in 5 types of organisms residing in the water column and/or sediment, e.g. Oncorhynchus mykiss, Pseudokirchneriella subcapitata, Daphnia magna, Chironmus riparius, and Lumbriculus variegates. Fish, algae or Daphnia were unaffected by acute exposures to water accommodated fractions of 110mg DBDP-Ethane/L. Chronic exposure to DBDP-Ethane at the highest dose tested, 5000mg/kg dry sediment, did not affect midge mean development times, emergence or development rates or oligochaete survival, reproduction or dry weight. The chronic EC50, LOEC and NOEC were ≥5000mg/kg in the two sediment species. Applying an assessment factor of 50, the unbounded predicted no effect concentration (PNEC(sediment)) was 100mg/kg dry sediment. The calculated PNEC indicates DBDPE-Ethane presents little risk to sediment organisms. These results add to DBDP-Ethane's existing database in the terrestrial compartment and mammals.