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Chem
Kinds of Chem Terms modified by Chem Selected AbstractsA Versatile System for Arbitrary Function Large-Amplitude Fourier Transformed VoltammetryELECTROANALYSIS, Issue 13 2007Lishi Wang Abstract A novel low-cost instrument for arbitrary function large-amplitude Fourier transformed voltammetry was developed. Description of both hardware and software was given in detail in this paper. A micro-control-unit (MCU) in combination with a field programmable gate array (FPGA) was designed to act as the controller of the instrument. Profiting from the built-in USB2.0 standard interface of the MCU, vast amount of data to/from the high resolution digital-to-analog converter (DAC)/analog-to-digital converter (ADC) then could be exchanged with computer in real-time, instead of being temporarily stored at the capacity limited memory of the instrument which always restricted the length of sampling time and the size of the collected data set. In the [Fe(CN)6]4+/3+ system, by superimposing a sinusoidal waveform with an amplitude of 120,mV onto a triangular potential and then applying to a macro electrode through the instrument, voltammograms up to the eighth harmonic could be well resolved by FT-IFT method. Excellent agreement was attained with Bond's similar experiment [Anal. Chem. 76 (2004) 3619] in respect of the shape and relative peak height of each harmonic. With the simply structured instrument, stable performance, flexible and versatile function was achieved. Arbitrary forms of AC perturbation which may not necessarily be sinusoidal or square-wave or other regular formed periodic signal could be synthesized and superimposed onto a DC potential as the excitation signal with this instrument. Some more useful electrode process information was expected to unveil by utilizing the FT-IFT algorithm to dissect the response signal. [source] Optimal separation times for electrical field flow fractionation with Couette flowsELECTROPHORESIS, Issue 20 2008Jennifer Pascal Abstract The prediction of optimal times of separation as a function of the applied electrical field and cation valence have been studied for the case of field flow fractionation [Martin M., Giddings J. C., J. Phys. Chem. 1981, 85, 727] with charged solutes. These predictions can be very useful to a priori design or identify optimal operating conditions for a Couette-based device for field flow fractionation when the orthogonal field is an electrical field. Mathematically friendly relationships are obtained by applying the method of spatial averaging to the solute species continuity equation; this is accomplished after the role of the capillary geometrical dimensions on the applied electrical field equations has been assessed [Oyanader M. A., Arce P., Electrophoresis 2005; 26, 2857]. Moreover, explicit analytical expressions are derived for the effective parameters, i.e. diffusivity and convective velocity as functions of the applied (orthogonal) electrical field. These effective transport parameters are used to study the effect of the cation valence of the solutes and of the magnitude of the applied orthogonal electrical field on the values of the optimal time of separation. These parameters play a significant role in controlling the optimal separation time, leading to a family of minimum values, for particular magnitudes of the applied orthogonal electrical field. [source] Environmental concentrations of methoprene and its transformation products after the treatment of Altosid® XR Briquets in the city of Richmond, British Columbia, CanadaENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 10 2010Jen-ni Kuo Abstract Water runoff from catch basins treated with Altosid® XR Briquets for mosquito larvae control was sampled at 10 storm drainage pump stations along the outskirts of the city of Richmond, British Columbia, Canada after rainfall events in 2006 to determine the residual concentrations of methoprene and transformation products: citronellic acid, methoprene acid, and 7-methoxycitronellic acid. Runoff of prior-to-treatment, posttreatment, and 150-d-after-treatment was collected. No residues were detected in the prior-to-treatment samples. However, methoprene was detected in posttreatment, and citronellic acid was detected in posttreatment and one 150-d-after-treatment sample. The detected environmental concentrations of methoprene (0.04,0.14,µg/L) and methoprene acid (0.07,µg/L) at pump stations were below known/reported toxicity values to aquatic organisms. However, concentrations detected inside the storm drainage system in catch basins (methoprene 122,µg/L, methoprene acid 1.74,µg/L) and inspection chambers (methoprene 622,µg/L, methoprene acid 20,µg/L, citronellic acid 0.05,µg/L) are known to be toxic to invertebrates, have chronic early-life-stage fish effects, and exceeded the Draft Interim Ontario Water Quality Objective and the numerical benchmarks for protection of amphibians (1.6,µg/L), invertebrates (10,µg/L), and fish (80,µg/L). The limited detection in the present study may have resulted from significant absorption of methoprene to sample bottle walls, substance decay during sample storage before methoprene extraction, flushing of briquettes from catch basins following heavy rainfall, and the burial of briquettes under thick layers of debris. Environ. Toxicol. Chem. 2010;29:2200,2205. © 2010 SETAC [source] Patterns of organic contaminants in eggs of an insectivorous, an omnivorous, and a piscivorous bird nesting on the Hudson River, New York, USAENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 10 2010Christine M. Custer Abstract Belted kingfisher (Ceryle alcyon), spotted sandpiper (Actitus macularia), and tree swallow (Tachycineta bicolor) eggs were collected in 2004 from the upper Hudson River, New York, USA. This area is one of the most polychlorinated biphenyl (PCB)-contaminated locations in North America. Multivariate analyses indicated among species differences in the concentration and composition of PCB congeners, polychlorinated dibenzo- p -dioxin (PCDD), and dibenzofuran (PCDF, PCDD-F when combined with PCDDs) congeners, and chlorinated pesticides. Total PCB concentrations followed the typical food chain biomagnification paradigm of higher concentrations in piscivorous bird eggs and lower concentrations in eggs of species that feed at lower trophic levels. Concentrations in the insectivorous swallows (geometric mean,=,6.8,µg/g wet wt) were approximately half the concentrations present in the piscivorous kingfisher (11.7,µg/g) or omnivorous sandpiper (12.6,µg/g). In contrast, PCB toxic equivalents (TEQs) were higher in swallows (1,790,pg/g wet wt) than in either kingfishers (776,pg/g) or sandpipers (881,pg/g). This difference can be mainly attributed to higher PCB77 concentrations in swallows relative to the other two species. Also contrary to the accepted food-chain paradigm, the sum of PCDD-F concentrations and the sum of their TEQs were higher in swallows than in either sandpipers or kingfishers. Metabolic pathway differences in the respective food chains of the three species probably accounted for the differences observed in PCB TEQ, total PCDD-F, and PCDD-F TEQ concentrations among species. Environ. Toxicol. Chem. 2010;29:2286,2296. © 2010 SETAC [source] Chronic copper toxicity in the estuarine copepod Acartia tonsa at different salinitiesENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 10 2010Mariana M. Lauer Abstract Chronic Cu toxicity was evaluated in the euryhaline copepod Acartia tonsa. Male and female copepods were exposed (6 d) separately to different combinations of Cu concentration and water salinity (5, 15, and 30 ppt) using different routes of exposure (waterborne, waterborne plus dietborne, and dietborne). After exposure, groups of one male and three female copepods were allowed to reproduce for 24,h. In control copepods, egg production augmented with increasing water salinity. However, egg hatching rate did not change. Copper exposure reduced egg production and hatching rate in all water salinities tested, but the reproductive response was dependent on the route of Cu exposure. Median effective concentration (EC50) values for egg production after waterborne exposure were 9.9, 36.8, and 48.8,µg/L dissolved Cu at water salinities of 5, 15, and 30 ppt, respectively. For waterborne plus dietborne exposure, they were significantly higher (40.1, 63.7, and 109.9,µg /L, respectively). After dietborne exposure, approximately 40% decrease in egg production was observed, independently of Cu concentration and water salinity tested. At water salinities of 5 and 30 ppt, egg hatching rate reduced after waterborne exposure, together or not with the dietborne exposure. At water salinity of 15 ppt, Cu toxicity was only observed after dietborne exposure. Data indicate that egg production is a more reliable reproductive endpoint to measure chronic Cu toxicity in copepods than egg hatching rate in a wide range of water salinities. They also suggest that both water salinity and route of Cu exposure should be taken into account in the development of a chronic biotic ligand model version for estuarine and marine environments. Environ. Toxicol. Chem. 2010;29:2297,2303. © 2010 SETAC [source] Early signs of lethal effects in Daphnia magna (Branchiopoda, Cladocera) exposed to the insecticide cypermethrin and the fungicide azoxystrobinENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 10 2010Ursula Friberg-Jensen Abstract This study presents the effects of sublethal concentrations of pesticides cypermethrin and azoxystrobin on the activity of several physiological parameters of egg-carrying Daphnia magna studied using a video-image technique. Single tethered daphnids were continuously recorded for 24,h of pesticide exposure, and the activity of the heart, the filtering limbs, the mandibles, and the focal spine were subsequently analyzed. Acute toxicity tests based on the criteria of immobilization were performed on egg-carrying D. magna, and sublethal concentrations of 0.1, 1.0, and 10,µg/L cypermethrin and 0.5, 1.0, and 2.0,mg/L azoxystrobin were established. At a concentration as low as 0.1,µg/L cypermethrin, the 5% effective concentration after 24,h of exposure (EC5,24h), the activity of the focal spine increased and the filtering limb activity decreased. The activity of the mandibles was reduced by exposure to 1.0 (EC18,24,h) and 10,µg/L (EC41,24,h) cypermethrin, whereas heart activity increased at a concentration of 10,µg/L (EC41,24,h). With regard to azoxystrobin, the activity of all response parameters except the focal spine decreased by exposure to 0.5,mg/L (EC4,24h) azoxystrobin. The focal spine was not affected by azoxystrobin. The results show that physiological mechanisms important for ingestion of food in D. magna may be impaired by low concentrations of commonly used pesticides. Environ. Toxicol. Chem. 2010;29:2371,2378. © 2010 SETAC [source] Presence of natural and anthropogenic organic contaminants and potential fish health impacts along two river gradients in Alberta, CanadaENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 10 2010Ken M. Jeffries Abstract In the current study, 28 organic contaminants were measured, many with estrogen-like activity, in water collected from 16 sites on two rivers in the South Saskatchewan River Basin, Alberta, Canada. The compounds detected included synthetic estrogens (birth control pill compounds and hormone therapy drugs) downstream of municipal wastewater effluents and natural hormones downstream of municipal wastewater effluents and in agricultural areas. Greater concentrations of cholesterol and derivatives, phytosterols, and fecal sterols were measured at the most downstream sites, which indicates cumulative inputs of such compounds in these rivers. A native minnow (longnose dace, Rhinichthys cataractae) was sampled to assess pathophysiological responses to exposure to compounds with estrogen-like activity. Hepatic vitellogenin protein was detected in at least one adult male longnose dace from 14 of 15 sites sampled for fish. Vitellogenin was negatively correlated with hepatosomatic (r,=,,0.47, p,<,0.001) and gonadosomatic (r,=,,0.44, p,<,0.003) indices, which suggests potential health impacts in male longnose dace in the South Saskatchewan River Basin. The current study demonstrates that organic contaminants, many with estrogen-like activity, are distributed over hundreds of kilometers throughout the South Saskatchewan River Basin and not just downstream of major point-sources. Therefore, many activities within these basins impact water quality in the South Saskatchewan River Basin and affect endemic longnose dace populations. Environ. Toxicol. Chem. 2010;29:2379,2387. © 2010 SETAC [source] Evaluation of sorbent amendments for in situ remediation of metal-contaminated sedimentsENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 9 2010Seokjoon Kwon Abstract The present study evaluated sorbent amendments for in situ remediation of sediments contaminated with two divalent metals. A literature review screening was performed to identify low-cost natural mineral-based metal sorbents and high-performance commercial sorbents that were carried forward into laboratory experiments. Aqueous phase metal sorptivity of the selected sorbents was evaluated because dissolved metals in sediment porewater constitute an important route of exposure to benthic organisms. Based on pH-edge sorption test results, natural sorbents were eliminated due to inferior performance. The potential as in situ sediment amendment was explored by comparing the sorption properties of the engineered amendments in freshwater and saltwater (10 PPT salinity estuarine water) matrices. Self-assembled monolayers on mesoporous supports with thiols (Thiol-SAMMSÔ) and a titanosilicate mineral (ATSÔ) demonstrated the highest sorption capacity for cadmium (Cd) and lead (Pb), respectively. Sequential extraction tests conducted after mixing engineered sorbents with contaminated sediment demonstrated transfer of metal contaminants from a weakly bound state to a more strongly bound state. Biouptake of Cd in a freshwater oligochaete was reduced by 98% after 5-d contact of sediment with 4% Thiol-SAMMS and sorbed Cd was not bioavailable. While treatment with ATS reduced the small easily extractable portion of Pb in the sediment, the change in biouptake of Pb was not significant because most of the native lead was strongly bound. The selected sorbents added to sediments at a dose of 5% were mostly nontoxic to a range of sensitive freshwater and estuarine benthic organisms. Metal sorbent amendments in conjunction with activated carbon have the potential to simultaneously reduce metal and hydrophobic contaminant bioavailability in sediments. Environ. Toxicol. Chem. 2010;29:1883,1892. © 2010 SETAC [source] Environmental factors affecting the levels of legacy pesticides in the airshed of Delaware and Chesapeake Bays, USAENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 9 2010Anubha Goel Abstract Organochlorine insecticides and their degradation products contribute to toxicity in Chesapeake Bay, USA, sediments and affect the reproductive health of avian species in the region; however, little is known of atmospheric sources or temporal trends in concentrations of these chemicals. Weekly air (n,=,265) and daily rain samples (n,=,494) were collected over 2000 to 2003 from three locations in the Delmarva Peninsula, USA. Pesticides were consistently present in the gas phase with infrequent detection in the particle phase. Hexachlorocyclohexanes (HCHs) and cis - and trans -chlordane were detected most frequently (95,100%), and cis - and trans -nonachlor, oxychlordane, heptachlor, heptachlor epoxide, dieldrin, and 1-chloro-4-[2,2-dichloro-1-(4-chlorophenyl)ethenyl]benzene (4,4,-DDE) were also detected frequently. The highest mean air concentrations were for dieldrin (60,84,pg/m3), ,-HCH (37,83,pg/m3), and 4,4,-DDE (16,80,pg/m3). Multiple regression analyses of air concentrations with temperature and wind conditions using modified Clausius-Clapeyron equations explained only 30 to 60% of the variability in concentration for most chemicals. Comparison of the air concentrations and enthalpy of air,surface exchange values at the three sites indicate sources of chlordanes and ,-HCH sources are primarily from long-range transport. However, examination of chlordane isomer ratios indicates some local and regional contributions, and ,-HCH, 4,4,-DDE, dieldrin, heptachlor, heptachlor epoxide, and oxychlordane also have local or regional sources, possibly from contaminated soils. Median rain sample volumes of 1 to 3 L led to infrequent detections in rain; however, average measured concentrations were 2 to 10 times higher than in the Great Lakes. Dissipation half-lives in air were well below 10 years for all chemicals and below published values for the Great Lakes except dieldrin, which did not decline during the sample period. Environ. Toxicol. Chem. 2010;29:1893,1906. © 2010 SETAC [source] Toxicity of brominated volatile organics to freshwater biotaENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 9 2010Monique T. Binet Abstract As part of a larger study investigating the fate and effects of brominated volatile organic compounds (VOCs) in contaminated groundwaters discharging to surface waters, the toxicity of 1,2 dibromoethene (DBE) and 1,1,2-tribromoethene (TriBE) to freshwater aquatic biota was investigated. Their toxicity to bacteria (Microtox®), microalgae (Chlorella sp.), cladocerans (Ceriodaphnia dubia), duckweed (Lemna sp.) and midges (Chironomus tepperi) was determined after careful optimization of the test conditions to minimize chemical losses throughout the tests. In addition, concentrations of DBE and TriBE were carefully monitored throughout the bioassays to ensure accurate calculation of toxicity values. 1,2-Dibromoethene showed low toxicity to most species, with concentrations to cause 50% lethality or effect (LC/EC50 values) ranging from 28 to 420,mg/L, 10% lethality or effect (LC/EC10 values) ranging from 18 to 94,mg/L and no-observed-effect concentrations (NOECs) ranging from 22 to 82,mg/L. 1,1,2-Tribromoethene was more toxic than DBE, with LC/EC50 values of 2.4 to 18,mg/L, LC/EC10 values of 0.94 to 11,mg/L and NOECs of 0.29 to 13,mg/L. Using these limited data, together with data from the only other published study on TriBE, moderate-reliability water quality guidelines (WQGs) were estimated from species sensitivity distributions. The proposed guideline trigger values for 95% species protection with 50% confidence were 2,mg/L for DBE and 0.03,mg/L for TriBE. The maximum concentrations of DBE and TriBE in nearby surface waters (3 and 1,µg /L, respectively) were well below these WQGs, so the risk to the freshwater environment receiving contaminated groundwater inflows was considered to be low, with hazard quotients <1 for both VOCs. Environ. Toxicol. Chem. 2010;29:1984,1993. © 2010 SETAC [source] Exposure of three generations of the estuarine sheepshead minnow (Cyprinodon variegatus) to the androgen, 17,-trenbolone: Effects on survival, development, and reproductionENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 9 2010Geraldine M. Cripe Abstract Estimating long-term effects of endocrine-disrupting chemicals on a species is important to assessing the overall risk to the populations. The present study reports the results of a 42-week exposure of estuarine sheepshead minnows (Cyprinodon variegatus) to the androgen, 17,-trenbolone (Tb) conducted to determine if partial-(F0) or single-generation (F1) fish exposures identify multigenerational (F0,F3) effects of androgens on fish. Adult F0 fish were exposed to 0.007, 0.027, 0.13, 0.87,and 4.1,µg Tb/L, the F1 generation to ,0.87,µg Tb/L, the F2 fish to ,0.13,µg Tb/L, and the F3 fish to ,0.027,µg Tb/L. The highest concentrations with reproducing populations at the end of the F0, F1, and F2 generations were 4.1, 0.87, and 0.027,µg Tb/L, respectively. Reproduction in the F0, F1, and F2 generations was significantly reduced at 0.87, 0.027, and 0.027,µg Tb/L, respectively. Fish were significantly masculinized in the F1 generation exposed to 0.13 µg Tb/L or greater. Female plasma vitellogenin was significantly reduced in F0 fish exposed to ,0.87,µg Tb/L. Gonadosomatic indices of the F0 and F1 generations were significantly increased at 0.87 and 0.13 µg Tb/L in the F0 and F1 generation, respectively, and were accompanied by ovarian histological changes. Reproduction was the most consistently sensitive measure of androgen effects and, after a life-cycle exposure, the daily reproductive rate predicted concentrations affecting successive generations. The present study provides evidence that a multiple generation exposure of fish to some endocrine-disrupting chemicals can result in developmental and reproductive changes that have a much greater impact on the success of a species than was indicated from shorter term exposures. Environ. Toxicol. Chem. 2010;29:2079,2087. © 2010 SETAC [source] 2,3,4,7,8-pentachlorodibenzofuran is a more potent cytochrome P4501A inducer than 2,3,7,8-tetrachlorodibenzo- p -dioxin in herring gull hepatocyte culturesENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 9 2010Jessica C. Hervé Abstract Concentration-dependent effects of 2,3,7,8-tetrachlorodibenzo- p -dioxin (TCDD), 2,3,4,7,8-pentachlorodibenzofuran (PeCDF), and 2,3,7,8-tetrachlorodibenzofuran (TCDF) on cytochrome P4501A (CYP1A) induction were determined in primary cultures of embryonic herring gull (Larus argentatus) hepatocytes exposed for 24,h. Based on the concentration that induced 50% of the maximal response (EC50), the relative potencies of TCDD and TCDF did not differ by more than 3.5-fold. However, also based on the EC50, PeCDF was 40-fold, 21-fold, and 9.8-fold more potent for inducing ethoxyresorufin- O -deethylase (EROD) activity, CYP1A4 mRNA expression, and CYP1A5 mRNA expression than TCDD, respectively. The relative CYP1A-inducing potencies of PeCDF and of other dioxin-like chemicals (DLCs) in herring gull hepatocytes (HEH RePs), along with data on concentrations of DLCs in Great Lakes herring gull eggs, were used to calculate World Health Organization toxic equivalent (WHO-TEQ) concentrations and herring gull embryonic hepatocyte toxic equivalent (HEH-TEQ) concentrations. The analysis indicated that, when using avian toxic equivalency factors (TEFs) recommended by the WHO, the relative contribution of TCDD (1.1,10.2%) to total WHO-TEQ concentration was higher than that of PeCDF (1.7,2.9%). These results differ from the relative contribution of TCDD and PeCDF when HEH RePs were used; PeCDF was a major contributor (36.5,52.9%) to total HEH-TEQ concentrations, whereas the contribution by TCDD (1.2,10.3%) was less than that of PeCDF. The WHO TEFs for avian species were largely derived from studies with the domestic chicken (Gallus gallus domesticus). The findings of the present study suggest that it is necessary to determine the relative potencies of DLCs in wild birds and to re-evaluate their relative contributions to the biochemical and toxic effects previously reported in herring gulls and other avian species. Environ. Toxicol. Chem. 2010;29:2088,2095. © 2010 SETAC [source] Relationship between biotic ligand model-based water quality criteria and avoidance and olfactory responses to copper by fishENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 9 2010Joseph S. Meyer Abstract The U.S. Environmental Protection Agency's (U.S. EPA) water quality criteria for Cu were tested to determine whether they protect fish against neurophysiological impairment. From published studies with rainbow trout (Oncorhynchus mykiss), Chinook salmon (Oncorhynchus tshawytscha), coho salmon (Oncorhynchus kisutch), and fathead minnows (Pimephales promelas), 20% inhibition concentrations (IC20s) were calculated for avoidance of Cu-containing water and for impairment of electroencephalogram (EEG) and electro-olfactogram (EOG) responses to natural odorants in Cu-containing water. Additionally, a Cu-olfactory biotic ligand model (BLM) that fits the coho salmon EOG data was parameterized by changing the sensitivity parameter in the ionoregulatory-based BLM. The IC20s calculated from reported Cu avoidance, EEG, and EOG data and IC20s predicted by the olfactory BLM were compared with acute and chronic Cu criteria calculated using U.S. EPA's BLM 2007 or hardness-adjustment equations. The BLM-based chronic criteria were protective in all 16 exposure water,species combinations used in avoidance and olfaction experiments. Additionally, the BLM-based acute criteria were protective in all 11 exposure water,species combinations in which comparisons could be made with olfactory BLM-predicted IC20s but not in two of the 16 exposure water,species combinations in which comparisons could be made with the reported IC20s (which were ,8% lower than but did not differ significantly from the BLM-based acute criteria; p,>,0.05). In effect, the olfactory BLM factored out the relatively high variability in the reported IC20s. It is concluded that the U.S. EPA's BLM-based water quality criteria for Cu protect against these types of neurophysiological impairment in the six species,endpoint combinations analyzed in this paper. However, the U.S. EPA's hardness-based criteria for Cu sometimes were considerably underprotective and sometimes were much less protective than the BLM-based criteria. Environ. Toxicol. Chem. 2010;29:2096,2103. © 2010 SETAC [source] Occurrence and fate of micropollutants in the Vidy Bay of Lake Geneva, Switzerland.ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 8 2010Part I: Priority list for environmental risk assessment of pharmaceuticals Abstract Pharmaceuticals are substances designed to have a biological effect in humans. Their presence in the environment, especially in surface waters, is of increasing concern because of their potential risk to non-target species. A large number of pharmaceuticals are on the market; for example, approximately 2,000 active ingredients are approved in Europe, and many of them have already been detected in surface water. It is therefore crucial to select the substances that may do the most harm to the environment prior to performing measurements and extensive risk assessment. In the present study, a method to determine a list of pharmaceuticals to survey in surface water is proposed. Inclusion of substances on the list was based on a screening procedure, the analytical feasibility, and previous knowledge of pharmaceuticals detected in water. The screening procedure proposed here is an improvement on the standard procedure of the European Medicine Evaluation Agency (EMEA). It is designed to decrease the number of pharmaceuticals to be evaluated in a stepwise manner, thus decreasing the number of data necessary for the evaluation. We applied our approach to determine a list of 37 pharmaceuticals and four hormones to survey in a specific region of Switzerland, the Lake Geneva area, and discussed the advantages and weak points of the method. Environ. Toxicol. Chem. 2010; 29:1649,1657. © 2010 SETAC [source] Occurrence and fate of micropollutants in the Vidy Bay of Lake Geneva, Switzerland.ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 8 2010Part II: Micropollutant removal between wastewater, raw drinking water Abstract The occurrence and removal of 58 pharmaceuticals, endocrine disruptors, corrosion inhibitors, biocides, and pesticides, were assessed in the wastewater treatment plant (WWTP) of the city of Lausanne, Switzerland, as well as in the effluent-receiving water body, the Vidy Bay of Lake Geneva. An analytical screening method to simultaneously measure all of the 58 micropollutants was developed based on ultra performance liquid chromatography coupled to a tandem mass spectrometer (UPLC-MS/MS). The selection of pharmaceuticals was primarily based on a prioritization study, which designated them as environmentally relevant for the Lake Geneva region. Except for the endocrine disruptor 17,-ethinylestradiol, all substances were detected in 24-h composite samples of wastewater entering the WWTP or in the treated effluent. Of these compounds, 40% were also detected in raw drinking water, pumped from the lake 3,km downstream of the WWTP. The contributions of dilution and degradation to micropollutant elimination between the WWTP outlet and the raw drinking water intake were established in different model scenarios using hypothetical residence times of the wastewater in Vidy Bay of 1, 4, or 90 d. Concentration decrease due to processes other than dilution was observed for diclofenac, beta-blockers, several antibiotics, corrosion inhibitors, and pesticides. Measured environmental concentrations (MECs) of pharmaceuticals were compared to the predicted environmental concentrations (PECs) determined in the prioritization study and agreed within one order of magnitude, but MECs were typically greater than the corresponding PECs. Predicted no-effect concentrations of the analgesic paracetamol, and the two antibiotics ciprofloxacin and sulfamethoxazole, were exceeded in raw drinking water samples and therefore present a potential risk to the ecosystem. Environ. Toxicol. Chem. 2010; 29:1658,1668. © 2010 SETAC [source] Multi-generational effects of polybrominated diphenylethers exposure: Embryonic exposure of male American kestrels (Falco sparverius) to DE-71 alters reproductive success and behaviorsENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 8 2010Sarah C. Marteinson Abstract Polybrominated diphenylethers (PBDEs) are additive flame-retardants that are environmentally persistent and bioaccumulative compounds of particular concern to species at high trophic levels, including predatory birds. The developmental effects of in ovo exposure to male birds at environmentally relevant levels of the PBDE technical mixture, DE-71, on reproductive success and behaviors using captive American kestrels (Falco sparverius) were determined. Males were exposed in ovo by direct maternal transfer to DE-71 and unintentionally to low concentrations of hexabromocyclododecane (HBCD) at three mean,±,standard error DE-71 concentrations of 288.60,±,33.35,ng/g wet weight (low-exposure), 1130.59,±,95.34,ng/g wet weight (high-exposure), or background levels of 3.01,±,0.46,ng/g wet weight (control). One year following exposure, males were paired with unexposed females. Reproductive success was lower in the high exposure pairs: 43% failed to lay eggs while all other pairs laid complete clutches; they also laid smaller clutches and produced smaller eggs with reduced fertility, parameters that were negatively correlated with paternal in ovo concentrations of all PBDEs, as well as individual congeners and HBCD. Throughout courtship, there were fewer copulations by all in ovo exposed males, fewer mate-calls made by high-exposure males, and decreasing trends in pair-bonding and nest-box behaviors across treatments that continued during brood rearing. The reductions in clutch size and fertility were associated with the reduced frequencies of male courtship behaviors, and were associated with increasing concentrations of the PBDE congeners BDE-47, -99, -100, -53, -138, and HBCD. The results of the present study confirm effects noted in the F0 generation and demonstrate that exposure to DE-71 affects multiple generations of this predatory avian species at environmentally relevant levels of exposure. Environ. Toxicol. Chem. 2010; 29:1740,1747. © 2010 SETAC [source] Long-term trends in liver neoplasms in brown bullhead in the Buffalo River, New York, USAENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 8 2010Darrel J. Lauren Abstract The Buffalo River area of concern (AOC) was assigned an impaired status for the fish tumors and other deformities beneficial use impairment category by the New York State Department of Environmental Protection in 1989. This was initially based on an inadequately documented brown bullhead (Ameiurus nebulosus) feeding study using river sediment extracts. The presence of liver tumors was subsequently supported by reports of a 19 to 27% prevalence in wild brown bullhead between 1983 and 1988 and a 4.8% prevalence in 1998. However, neither fish size (or age) nor sample locations were given, and histopathological definitions were inconsistent in these previous studies. Therefore, in 2008, we re-evaluated the prevalence of hepatocellular and chloangiocellular tumors (as well as other gross indicators of fish health) in brown bullhead averaging 25,cm in length collected from three reaches of the Buffalo River and recorded our collection sites by global positioning system. Among the 37 fish of appropriate size collected, only three exhibited liver tumors (8%). The tumors were evenly distributed within the three reaches, and only hepatocellular tumors were found. There were no differences in the prevalence of hepatic foci of alteration, body weight, length, or hepatosomatic index among the three reaches, but the conditions factor was significantly lower in fish from reach 2. Natural attenuation of water and sediment quality are the most likely causes for the decrease in liver tumors. The prevalence of liver tumors between 1998 and 2008 in the Buffalo River is similar to that found in recovery-stage AOCs and some Great Lakes reference areas. Environ. Toxicol. Chem. 2010; 29:1748,1754. © 2010 SETAC [source] Acute copper toxicity in the euryhaline copepod Acartia tonsa: implications for the development of an estuarine and marine biotic ligand modelENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 8 2010Grasiela Lopes Leães Pinho Abstract Copepods (Acartia tonsa) were exposed (48 h) to waterborne, diet-borne (non-Cu-equilibrated and Cu-equilibrated food), and waterborne plus diet-borne Cu in either the absence or the presence of food (diatom Thalassiosira weissflogii). Toxicity tests were run in different salinities (5, 15, and 30 ppt) together with measurements of physicochemical parameters and total and dissolved Cu concentrations in the experimental media. Results show that most of the toxic Cu fraction was in the dissolved phase. In general, Cu toxicity was higher in low (5 ppt) than in high salinity (30 ppt), regardless of the pathway of Cu exposure tested. In the absence of food, data clearly indicate that differences in waterborne Cu toxicity can be explained by changes in water chemistry. However, addition of food (either non-Cu-equilibrated or Cu-equilibrated) to the experimental media protected against acute Cu toxicity in salinities 5 and 15 ppt, suggesting that A. tonsa requires extra energy to cope with the stressful condition imposed by Cu exposure associated with the ionoregulatory requirements in low salinities. For diet-borne exposure, a very high Cu concentration was necessary to precontaminate the diatoms to a level resulting in copepod mortality. Therefore, availability of food exerted a more important positive impact in protecting against acute Cu toxicity than its potential negative impact via contamination resulting in toxicity. Findings indicate the need for incorporation of both salinity and food in a future biotic ligand model (BLM) version for Cu in estuarine and marine waters. In this context, the euryhaline copepod A. tonsa would be a suitable model species with which to perform experiments to validate and calibrate any future saltwater BLM. Environ. Toxicol. Chem. 2010; 29:1834,1840. © 2010 SETAC [source] Subcellular distribution of zinc in Daphnia magna and implication for toxicityENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 8 2010Wen-Xiong Wang Abstract We examined the subcellular partitioning of zinc (Zn) in Daphnia magna both under acute and chronic exposures. In the acute Zn toxicity tests, the daphnids were exposed to different Zn concentrations for 48,h or to one lethal concentration (1,000,µg/L) for different durations (time to death for up to 47,h). Significant mortality of daphnids was observed when the newly accumulated Zn concentration reached a threshold level of approximately 40,µg/g wet weight (or 320,µg/g dry wt), approximately 3.5 times higher than the background tissue concentration (92,µg/g dry wt). Chronic exposure (14 d) to Zn resulted in nonobservable effect on survivorship and growth at newly accumulated tissue concentration of over 40,µg/g wet weight. With increasing Zn acute exposure, more Zn was partitioned into the cellular debris fraction, indicating that this fraction was presumably the first targeted site of binding for Zn upon entering the animals. The importance of other subcellular fractions either decreased accordingly or remained comparable. We found that the metal-sensitive fraction (Zn distribution in the organelles and heat-denatured proteins) did not predict the acute Zn toxicity in Daphnia. During chronic exposure, however, no major change of the subcellular partitioning of Zn with increasing Zn exposure was documented. Zinc was mainly found in the organelles and heat-stable protein fractions during chronic exposure, suggesting that any subcellular repartitioning occurred primarily during acute exposure. Metallothioneins were induced upon chronic Zn exposure, but its induction evidently lagged behind the Zn accumulation. Our present study showed that the subcellular fractionation approach could not be readily used to predict the acute and chronic toxicities of Zn in Daphnia. A tissue-based Zn accumulation approach with a threshold Zn tissue concentration was better in predicting acute Zn toxicity. Environ. Toxicol. Chem. 2010; 29:1841,1848. © 2010 SETAC [source] Sediment quality in near coastal waters of the Gulf of Mexico: Influence of Hurricane Katrina,ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 7 2010John M. Macauley Abstract The results of the present study represent a synoptic analysis of sediment quality in coastal waters of Lake Pontchartrain and Mississippi Sound two months after the landfall of Hurricane Katrina. Posthurricane conditions were compared to prehurricane (2000,2004) conditions, for sediment quality data. There were no exceedances of effects range median (ERM) sediment quality guideline values for chemical contaminants in any of the sediment samples collected from the Lake Pontchartrain or the Mississippi Sound study areas following the hurricane. Lower threshold effects range low (ERL) values were exceeded for As, Cd, and Ni at several stations in both survey areas, similar to levels of contamination observed prior to the hurricane. The comparison of sediment quality indicators before and after the hurricane suggests considerable stability of these systems with respect to short-term ecological impacts. Although other studies have shown storm-related changes could be detected (e.g., effects on benthic communities associated with shifts in salinity), there were no indications of widespread sediment contamination. Environ. Toxicol. Chem. 2010;29:1403,1408. © 2010 SETAC [source] Impact of changes in analytical techniques for the measurement of polychlorinated biphenyls and organochlorine pesticides on temporal trends in herring gull eggsENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 7 2010Shane R. de Solla Abstract Changes in analytical approaches during the tenure of monitoring programs for organochlorine (OC) pesticides and polychlorinated biphenyls (PCBs) may affect estimates of temporal trends. We used an in-house reference material to create multiplication factors to adjust the estimates of OC pesticides and PCBs (Aroclor equivalents) in Great Lake herring gull eggs analyzed using electron capture detection (1987,1997) to be more equivalent to estimates using mass spectrometric detection (1998,2005) as well as accompanying differences in analytical procedures. We examined temporal trends in contaminant concentrations in herring gull eggs using change point regressions, to determine whether significant changes in long-term trends were associated with analytical methodology. The highest frequency of change point occurrences shifted from 1997 (when analytical methodology was altered) to 2003 after data adjustment. The explanatory power (r2) of the regressions was lower after adjustment, although only marginally so (mean r2 difference,=,0.04). The initial rates of decline before change points in contaminant concentrations were generally slower after the data adjustment, but after any change points the declines were not significantly different. The regression models did not change for 83.3% of the cases. The effects on the interpretation of long-term temporal trends in herring gull eggs, although not negligible, were minor relative to the magnitude of the temporal changes. Environ. Toxicol. Chem. 2010;29:1476,1483. © 2010 SETAC [source] Occurrence of pharmaceuticals and hormones in sewage sludgeENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 7 2010Antonio Nieto Abstract The present study evaluates the presence of nine hormones and their conjugates and 20 pharmaceuticals such as anti-inflammatories, lipid regulators, and antibiotics among others in sewage sludge from two sewage treatment plants (STPs) in the Tarragona area (Spain) for the period March 2007 until March 2008. Target analytes have been determined using different methods involving pressurized liquid extraction and liquid chromatography (electrospray ionization) tandem mass spectrometry (MS-MS). Most of the pharmaceuticals and hormones were found at low micrograms per kilogram dry weight levels in the sewage sludge samples analyzed. Some compounds were present in all samples, such as acetaminophen, caffeine, carbamazepine, and ibuprofen, among others. Other compounds, such as estriol, were found only in the STP of Reus. The compounds that showed the highest concentration in both STPs were roxithromycin and tylosin (1,446 and 1,958,µg/kg dry wt, respectively). The presence of these compounds in sewage sludge demonstrated that they are partially or totally removed from the influent wastewater by sorption into the sewage sludge. Environ. Toxicol. Chem. 2010;29:1484,1489. © 2010 SETAC [source] Dual enantioselective effect of the insecticide bifenthrin on locomotor behavior and development in embryonic,larval zebrafishENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 7 2010Meiqing Jin Abstract Bifenthrin (BF) is a synthetic pyrethroid that targets the nervous system of insects and may have adverse effects on the behavior and development of nontarget organisms. However, no reports have been issued on the effects of different enantiomers on locomotor behavior for synthetic pyrethroids (SPs) in zebrafish, and whether locomotor activity is associated with the developmental toxicities remains unclear. In this study, enantioselectivity of BF (1S and 1R) on the acute locomotor activity and developmental toxicities of embryonic,larval zebrafish were first evaluated. The results indicated that 1R -BF was more toxic, causing morphological impairments, with a 96-h median effective concentration (EC50) of 226,µg/L for pericardial edema and 145,µg/L for curved body axis. Administration of 20,µg/L of one enantiomer of BF had differential effects on the locomotor activity of zebrafish larvae at 4 d postfertilization (dpf) under alternating light and dark conditions. Larvae treated with 1R -BF were not sensitive to the alteration of light to dark, and the locomotor activities were reduced to a level similar to that observed in light, which otherwise increased rapidly and markedly. However, 1S -BF did not alter the general pattern of zebrafish response to the light or dark compared with the control. The results demonstrated that the differential effects on development might have contributed to the enantioselectivity in the locomotor activity. The consistency of enantioselectivity with insecticidal activity may also indicate a common mode of action. Furthermore, 1R -BF accelerated the spontaneous movement and hatching process, whereas 1S -BF seemed to be inhibitory. The results suggest the need to link behavioral changes to developmental toxicities in order to achieve more comprehensive health risk assessments of chiral pesticides. Environ. Toxicol. Chem. 2010;29:1561,1567. © 2010 SETAC [source] Uptake kinetics and subcellular compartmentalization of cadmium in acclimated and unacclimated earthworms (Eisenia andrei)ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 7 2010Shuo Yu Abstract Acclimation to cadmium (Cd) levels exceeding background concentrations may influence the ability of earthworms to accumulate Cd with minimum adverse effects. In the present study, earthworms (Eisenia andrei) were acclimated by exposure to 20,mg/kg Cd (dry wt) in Webster soil for 28 d. A 224-d bioaccumulation test was subsequently conducted with both acclimated and unacclimated worms exposed in Webster soils spiked with 20,mg/kg and 100,mg/kg Cd (dry wt). Uptake kinetics and subcellular compartmentalization of Cd were examined. Results suggest that acclimated earthworms accumulated more Cd and required a longer time to reach steady state than unacclimated worms. Most of the Cd was present in the metallothionein (MT) fraction. Cadmium in the MT fraction increased approximately linearly with time and required a relatively longer time to reach steady state than Cd in cell debris and granule fractions, which quickly reached steady state. Cadmium in the cell debris fraction is considered potentially toxic, but low steady state concentrations observed in the present study would not suggest the potential for adverse effects. Future use of earthworms in ecological risk assessment should take into consideration pre-exposure histories of the test organisms. A prolonged test period may be required for a comprehensive understanding of Cd uptake kinetics and compartmentalization. Environ. Toxicol. Chem. 2010;29:1568,1574. © 2010 SETAC [source] Assessing the fate and effects of nano aluminum oxide in the terrestrial earthworm, Eisenia fetidaENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 7 2010Jessica G. Coleman Abstract Nano-sized aluminum is currently being used by the military and commercial industries in many applications including coatings, thermites, and propellants. Due to the potential for wide dispersal in soil systems, we chose to investigate the fate and effects of nano-sized aluminum oxide (Al2O3), the oxidized form of nano aluminum, in a terrestrial organism. The toxicity and bioaccumulation potential of micron-sized (50,200,µm, nominal) and nano-sized (11,nm, nominal) Al2O3 was comparatively assessed through acute and subchronic bioassays using the terrestrial earthworm, Eisenia fetida. Subchronic (28-d) studies were performed exposing E. fetida to nano- and micron-sized Al2O3 -spiked soils to assess the effects of long-term exposure. No mortality occurred in subchronic exposures, although reproduction decreased at ,3,000,mg/kg nano-sized Al2O3 treatments, with higher aluminum body burdens observed at 100 and 300,mg/kg; no reproductive effects were observed in the micron-sized Al2O3 treatments. In addition to toxicity and bioaccumulation bioassays, an acute (48-h) behavioral bioassay was conducted utilizing a soil avoidance wheel in which E. fetida were given a choice of habitat between control, nano-, or micron-sized Al2O3 amended soils. In the soil avoidance bioassays, E. fetida exhibited avoidance behavior toward the highest concentrations of micron- and nano-sized Al2O3 (>5,000,mg/kg) relative to control soils. Results of the present study indicate that nano-sized Al2O3 may impact reproduction and behavior of E. fetida, although at high levels unlikely to be found in the environment. Environ. Toxicol. Chem. 2010;29:1575,1580. © 2010 SETAC [source] Tissue-specific distribution and whole-body burden estimates of persistent organic pollutants in the bottlenose dolphin (Tursiops truncatus)ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 6 2010Jennifer E. Yordy Abstract Most exposure assessments for free-ranging cetaceans focus on contaminant concentrations measured in blubber, and few data are available for other tissues or the factors governing contaminant distribution among tissues. The goal of this study was to provide a detailed description of the distribution of persistent organic pollutants (POPs) within the common bottlenose dolphin (Tursiops truncatus) body and assess the role of lipid dynamics in mediating contaminant distribution. Thirteen tissues (brain, blubber, heart, liver, lung, kidney, mammary gland, melon, skeletal muscle, spleen, thyroid, thymus, and testis/uterus) were sampled during necropsy from bottlenose dolphins (n,=,4) and analyzed for lipid and 85 POPs, including polychlorinated biphenyls, organochlorine pesticides, and polybrominated diphenyl ethers. Significant correlations between tissue POP concentrations and lipid suggest that distribution of POPs is generally related to tissue lipid content. However, blubber:tissue partition coefficients ranged widely from 0.753 to 6.25, suggesting that contaminant distribution is not entirely lipid-dependent. Tissue-specific and whole-body contaminant burdens confirmed that blubber, the primary site of metabolic lipid storage, is also the primary site for POP accumulation, contributing >90% to the whole-body burdens. Observations also suggest that as lipid mobilizes from blubber, contaminants may redistribute, leading to elevated tissue concentrations. These results suggest that individuals with reduced blubber lipid may be at increased risk for exposure-related health effects. However, this study also provides evidence that the melon, a metabolically inert lipid-rich structure, may serve as an alternate depot for POPs, thus preventing the bulk of blubber contaminants from being directly available to other tissues. This unique physiological adaptation should be taken into consideration when assessing contaminant-related health effects in wild cetacean populations. Environ. Toxicol. Chem. 2010;29:1263,1273. © 2010 SETAC [source] Toxicity of the molybdate anion in soil is partially explained by effects of the accompanying cation or by soil pHENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 6 2010Jurgen Buekers Abstract Previous studies have shown that toxicity of cationic trace metals in soil is partially confounded by effects of the accompanying anions. A similar assessment is reported here for toxicity of an oxyanion, i.e., molybdate (MoO), the soil toxicity of which is relatively unexplored. Solubility and toxicity were compared between the soluble sodium molybdate (Na2MoO4) and the sparingly soluble molybdenum trioxide (MoO3). Confounding effects of salinity were excluded by referencing the Na2MoO4 effect to that of sodium chloride (NaCl). The pH decrease from the acid MoO3 amendment was equally referenced to a hydrochloric (HCl) treatment or a lime-controlled MoO3 treatment. The concentrations of molybdenum (Mo) in soil solution or calcium chloride (CaCl2) 0.01,M extracts were only marginally affected by either MoO3 or Na2MoO4 as an Mo source after 10 to 13 days of equilibration. Effects of Mo on soil nitrification were fully confounded by associated changes in salinity or pH. Effects of Mo on growth of wheat seedlings (Triticum aestivum L) were more pronounced than those on nitrification, and toxicity thresholds were unaffected by the form of added Mo. The Mo thresholds for wheat growth were not confounded by pH or salinity at incipient toxicity. It is concluded that oxyanion toxicity might be confounded in relatively insensitive tests for which reference treatments should be included. Environ. Toxicol. Chem. 2010;29:1274,1278. © 2010 SETAC [source] Influence of stability on the acute toxicity of CdSe/ZnS nanocrystals to Daphnia magnaENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 6 2010Heather E. Pace Abstract The acute toxicity of polymer-coated CdSe/ZnS quantum dots (QDs) to Daphnia magna was investigated using 48-h exposure studies. The principal objective was to relate the toxicity of QDs to specific physical and chemical aspects of the QD. As such, two different CdSe core diameters, 2,nm QDs (green-emitting) and 5,nm QDs (red-emitting), and two different surface coatings, polyethylene oxide (PEO) and 11-mercaptoundecanoic acid (MUA) were studied. The QDs were characterized before and after the 48-h exposure using fluorescence, ultrafiltrations (3 kDa), and inductively coupled plasma-atomic emission spectrometry (ICP-AES) metal analysis. In addition, flow field flow fractionation-inductively coupled plasma-mass spectrometry (Fl FFF-ICP-MS) was used as a more extensive characterization technique to determine particle size and composition as well as identify other potential constituents in the QD solutions. The more stable QDs (PEO) were found to be less acutely toxic than the QDs with accelerated dissolution (MUA), suggesting QD stability has significant impact on the nanoparticles' short-term toxicity. The emergence of dissolved Cd2+ in solution indicates that the toxicity of the MUA QDs is likely due to Cd poisoning, and a mass-based dose response occurred as a consequence of this mode of action. Alternatively, the PEO QDs caused acute toxicity without observed particle dissolution (i.e., no detectable metals were solubilized), suggesting an alternative mode of toxic action for these nanoparticles. Results of the present study suggest that using particle number, instead of mass, as a dose metric for the PEO QDs, produces markedly different conclusions, in that smaller core size does not equate to greater toxicity. Environ. Toxicol. Chem. 2010;29:1338,1344. © 2010 SETAC [source] Quick assessment of cytotoxins effect on Daphnia magna using in vivo fluorescence microscopyENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 6 2010Vera V. Teplova Abstract A novel approach to contaminant toxicity screening is proposed. The use of fluorescent microscopy with fluorescent dyes allows for assessing intoxication of Daphnia magna tissues, at various stages of exposure, to contaminants present in water. As shown, D. magna may not only be used as a test species in toxicity tests based on its lethality, but due to its translucency and application of fluorescent probes, separate steps of its intoxication and dying can be visualized. Using a variety of fluorescent probes, the present study also contributes to a better understanding of the toxicity mechanisms. Environ. Toxicol. Chem. 2010;29:1345,1348. © 2010 SETAC [source] Influence of soil type and organic matter content on the bioavailability, accumulation, and toxicity of ,-cypermethrin in the springtail Folsomia candidaENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 5 2010Bjarne Styrishave Abstract The influence of organic matter (OM) content on ,-cypermethrin porewater concentrations and springtail Folsomia candida accumulation was investigated in two soils with different levels of organic matter, a forest soil with a total organic carbon (TOC) content of 5.0% (OM,=,11.5%) and an agricultural soil with a TOC content of 1.3% (OM,=,4.0%). Also, the effects of ,-cypermethrin concentrations in soil and pore water and the influence of soil aging on springtail reproduction were investigated. Springtail reproduction was severely affected by increasing ,-cypermethrin in soil with 1.3% TOC; the median effective concentration value (EC50) was estimated to 23.4,mg/kg (dry wt). Reproduction was only marginally affected in the soil with 5.0% TOC, and no EC50 value could be estimated. However, when expressing ,-cypermethrin accumulation as a function of soil ,-cypermethrin concentrations, no difference was found between the two soil types, and no additional ,-cypermethrin uptake was observed at soil concentrations above approximately 200,mg/kg (dry wt). By using solid-phase microextraction (SPME), it could be demonstrated that ,-cypermethrin porewater concentrations were higher in the soil with low organic matter (LOM) content than in the soil with high organic matter (HOM) content. Furthermore, a clear relationship was found between ,-cypermethrin concentrations in springtails and porewater. Soil aging was not found to exert any effect on ,-cypermethrin toxicity toward springtails. The study indicates that the springtail's accumulation of ,-cypermethrin and reproduction is governed by ,-cypermethrin porewater concentrations rather than the total ,-cypermethrin concentration in soil. Environ. Toxicol. Chem. 2010;29:1084,1090. © 2010 SETAC [source] | ||||||||||||||||||||||||||||||||||