3.01 Advances in Bioaccumulation Science and Assessment (Part I)
3.01.T-01 Comprehensive Screening and Trophic Transfer Behaviour of Emerging Organic Contaminants in a Freshwater Food Web
Dr. Qiuguo Fu1, Corina Meyer1, Mr. Michael Patrick2, Verena Kosfeld3, Heinz Ruedel4, Jan Koschorreck5 and Juliane
Hollender6, (1)Eawag, Swiss Federal Institute of Aquatic Science and Technology, Switzerland, (2)UMTEC, Eastern Switzerland University of Applied Sciences (OST), Rapperswil-Jona, Switzerland, (3)Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Germany, (4)Fraunhofer IME - Institute for Molecular Biology and Applied Ecology, Germany,
(5)Umweltbundesamt, Umweltbundesamt, Berlin, Germany, (6)Eawag - Swiss federal Institute of Aquatic Science and Technology, Switzerland
Bioaccumulation and trophic transfer of persistent legacy contaminants have been intensively characterized, but little is known on the contaminants of emerging concern (CECs) in the freshwater food web. Herein, we comprehensively screened CECs with a focus on (semi) polar substances and further evaluated their trophic transfer behavior in one plankton, two mussel, and nine fish samples of a food chain in Lake Templin from Germany. With an effective multi-residue sample preparation method and high-resolution mass spectrometry-based target, suspect, and non-target screening, we characterized 477 targets and further screened unknown features in complex biota matrices. Of the 477 targets, 145 were detected and quantified in different species (0.02 - 3640 ng/g, dry weight). Additionally, the suspect and non-target analysis with experimental mass spectra libraries and in silico
techniques (MetFrag and SIRIUS4/CSI:FingerID) enabled further identification of 27 unknown compounds with 19 confirmed by reference standards. Overall, the detected compounds belong to a diverse group of chemicals, including 71 pharmaceuticals, 27 metabolites, 26 pesticides, 16 per- and polyfluoroalkyl substances (PFASs), 11 industrial chemicals, 4 plasticizers, 3 flame
retardants, and 14 others. Moreover, we determined the trophic magnification factor (TMF) of 34 CECs with >80% detection frequency, among which 6 PFASs including perfluorooctanesulfonic acid (PFOS), perfluorodecanoic acid (PFDA),
perfluorohexanesulfonic acid (PFHxS), perfluorotridecanoic acid (PFTrA), perfluorotetradecanoic acid (PFTeA), and
perfluoroundecanoic acid (PFUnA), exhibited biomagnification potential (TMF =1.8 - 4.2, p < 0.05), whereas 5 pharmaceuticals (phenazone, progesterone, venlafaxine, levamisole, and lidocaine) and 1 personal care product metabolite (galaxolidone) showed biodilution potential (TMF = 0.4 - 0.6, p < 0.05).
3.01.T-02 Lanthanide Distribution in Daphnia magna Via Nano-Sxrf Imaging
Ms. Marion Revel1, Kadda Medjoubi2, Andrew Hursthouse3 and Susanne Heise4, (1)Hamburg University of Applied Sciences (HAW Hamburg), Germany, (2)SOLEIL synchrotron, France, (3)University of the West of Scotland, United Kingdom, (4)Hamburg University of Applied Sciences, Hamburg, Germany
Rare earth elements (REE) are essential for many new technologies. Their increased application since the 1990s have led to elevated levels in aquatic system, and understanding their interaction with biological systems is an important area of research.
Tests with daphnids (water fleas) let assume, that e.g. lanthanum toxicity could be similar to copper. Because of a number of chemical properties between Ln3+ and Ca3+, Ln can block calcium channels and they interfere with signal recognition pathways and enzyme activity. All these toxic effects require uptake and potentially accumulation of REE into cells and tissues. But few data are available on the distribution of REE in organisms after exposure and on accumulated concentrations. In order to improve understanding of their bioavailability, the accumulation of two REE (La and Gd) in juvenile Daphnia magna has been measured at the NANOSCOPIUM hard X-ray scanning nanoprobe beamline of the synchrotron SOLEIL (Saint-Aubin, France). Neonates of less than 24h were exposed to 15 mg/L of La or Gd for 48 and 72h. At the end of the test, the survival organisms were dehydrated through an acetone-water series and dried in HDMS (1,1,1,3,3,3-hexamethyldisilazane) in order to be analysed by snchrotron nano-XRF (nano-SXRF). The measurement was performed with an incident monochromatic X-ray beam of 17.02 keV energy, producing nano-SXRF spectra for every pixel. The primary results showed a difference of distribution between La and Gd in the organism. Gd seemed to accumulate more than La and tended to be distributed in tissues. The accumulation increased over the exposure time and a stronger accumulation in the carapace was found at 72h compare to 48h. This may be due to the timing of the moulting. The first moult occurs in neonates before being exposed and the second after 48h. For 72h of exposure, La was found in the intestine tract and had a solid appearance in the hindgut. The ingestion of La was probably possible because of it precipitation either in the medium or in the animal’s intestine itself. According to the speciation modelling by Geochemist Workbench, La tends to complex and precipitate more easily than Gd in solution conditions. Any solid matter generated might be ingested by the daphnids while the free ions may be taken up into the cells by e.g. Ca-channels. In conclusion, the accumulation of La and Gd in daphnid could depend on their speciation and free ion concentration.
3.01.T-03 Anionic and Cationic Organic Compounds Show Distinct Bioaccumulation in Rainbow Trout Cell Cultures Fabian Gerhard Peter Balk1, Bastian Huesser2, Juliane Hollender1 and Kristin Schirmer3, (1)Eawag - Swiss federal Institute of Aquatic Science and Technology, Switzerland, (2)Eawag, Swiss Federal Institute of Aquatic Science and Technology, Switzerland, (3)Eawag, Switzerland
The assessment of chemicals for their bioaccumulative potential requires in vivo testing with fish. These tests are resource intense, costly, time consuming and of ethical concern due to the sacrifice of animals. Therefore, alternative in vitro models are being sought to replace these tests. We have started to explore how well rainbow trout (Oncorhynchus mykiss) cell lines, in particular RTL?W1 (liver) and RTgill?W1 (gill), can predict the bioaccumulation and biotransformation potential of ionizable organic compounds (IOC) in fish. IOC comprise a large proportion of the chemicals in commerce and are ubiquitously detected in the environment and biota. Based on the availability of high quality in vivo data and the substances’ charge state at physiological pH, four anionic and three cationic compounds were selected: Pentachlorophenol (PCP, CAS 87-86-5), Diclofenac (DCF, CAS 15307-79-6), Tecloftalam (TT,CAS 76280-91-6) and Benzotriazol-t-butyl-hydroxyl-phenyl propanoic acid (BHPP, CAS 84268-36-0);
and N,N,trimethyltetradecylamine (Q14, CAS 4574-04-3), N, dimethyldecylamine (T10, CAS 1120-24-7) and
N-methyldodecylamine (S12, CAS 7311-30-0). First, non-toxic chemical concentrations for each compound were determined using the acute cell toxicity assay according to OECD TG249. Resulting exposure concentrations for bioaccumulation assessment ranged from 5 µg/L to 200 µg/L, i.e. never higher than 1 µM. The kinetic experiments were performed over 48h and 72h for anions and cations, respectively, with a total of 6 sampling time points. Cell, medium and plastic fraction were sampled separately at each time point and measured using high resolution tandem mass spectrometry after online solid phase extraction (for anions) or with direct injection of extracts (for cations). The anionic compounds, given as a fraction of the total compound mass in the test system, accumulated in the following order in RTL-W1 cells: BHPP (6%) > TT (4%) > DCF and PCP (below limit of
quantification, 0.07 to 0.45% respectively). In contrast, the thus far tested cations were associated with cells to a much larger extent, measured in RTgill-W1 as follows: 43% for T10 and 91% for S12. A comparison of the compounds’ baseline
bioconcentration factors and the in vitro derived steady-state bioconcentration factors gave a positive correlation (R2= 0.79), with deviations being within the 10-fold range of the line of unity.
3.01.T-04 Assessing Bioaccumulation of Silver Nanoparticles in Freshwater Benthic Invertebrates: From Single-Species to Mesocosm Approaches
Patricia Silva1, Cornelis A.M. (Kees) van Gestel2 and Susana Loureiro1, (1)Universidade de Aveiro, Portugal, (2)Vrije Universiteit Amsterdam, Netherlands
A sustainable nanotechnology development requires a robust environmental risk assessment. In line with this, studies on the toxicokinetics and bioaccumulation of engineered nanomaterials (ENMs) have been highly requested by regulatory bodies.
Aiming to contribute to this, the present study focused on understanding the toxicokinetics of different pristine silver nanoparticles (Ag NPs), silver sulfide nanoparticles (Ag2S NPs, used as model of an environmentally aged Ag NP form) and AgNO3 in the ecological relevant freshwater benthic species Physa acuta (pond snail), Chironomus riparius (non-biting midge) and Girardia tigrina (planarian). An integrated methodology was used, from lower (single-species bioaccumulation tests using different exposure routes) to higher tier (mesocosms, simulating a freshwater stream environment) approaches. Single-species tests with P. acuta revealed fast uptake and elimination of Ag from Ag2S NPs in all experiments, and water exposure was the predominant Ag uptake route. C. riparius larvae consistently revealed higher Ag uptake upon exposure to Ag2S NPs. In the individual chironomid exposures to water and sediment, Ag uptake was better explained by exposure to water than from the ingestion of sediment particles, while upon food exposure the larvae only revealed Ag uptake in the Ag2S NP treatment. The Ag transfer from larvae to adult midges appeared to be limited. Planarians accumulated Ag from the food in Ag2S NP and AgNO3
treatments, uptake being higher for AgNO3 exposures. The three species bioaccumulated Ag in Ag2S NP and AgNO3 exposures in the mesocosm test but showed higher internal Ag concentrations upon exposure to AgNO3. The uptake observed in the Ag2S NP treatment was likely in the particulate form, showing the bioavailability of this more environmentally persistent and relevant Ag nanoparticulate form in a more realistic exposure scenario. Single-species tests underestimated bioaccumulation when compared with mesocosms, albeit in some cases similar uptake patterns were observed. No apparent risk for biomagnification was observed in the food chain P. acuta à G. tigrina upon exposure to Ag2S NPs in single-species and mesocosm tests. This work provides important data for modelling the potential exposure and bioaccumulation of relevant Ag forms in freshwater benthic environments and may be useful for predictive models for nanoregulation purposes, contributing to improving the environmental risk
assessment of ENMs.
3.01.T-05 Poster Spotlight [3.01.P-Mo095 | 3.01.P-Mo096 |3.01.P-Mo098]
Visit poster session for abstracts
3.01 Advances in Bioaccumulation Science and Assessment (Part II)
3.01.T-06 Using In-Vitro Biotransformation Rates to Estimate the Bioaccumulation Potential of 6 Different Siloxane Compounds
Mark Cantu, Beatrice Chee and Frank Gobas, Simon Fraser University, Canada
Siloxanes are produced globally in high volumes and are considered substances of concern in the EU. Siloxanes pose a unique challenge to assess for their environmental and human health impacts due to their superhydrophobicity, high volatility, and their universal presence, including their use in analytical instrumentation. Using OECD Test Guideline 319B to conduct the in-vitro studies, we looked at the depletion rates of 6 different siloxanes in both Rainbow trout and mammalian sub-cellular fractions.
Octamethyltrisiloxane (L3), decamethyltetrasiloxane (L4), dodecamethylpentasiloxane (L5), octamethylcyclotetrasiloxane (D4), Decamethylcyclopentasiloxane (D5), and dodecamethylcyclohexasiloxane (D6) biotransformation rates were determined in both aquatic and mammalian liver S9 fractions and incorporated into in-vitro to in-vivo extrapolation models (IVIVE) to predict the bioconcentration factors of the 6 siloxanes. Each siloxane was run separately in replicates of 3, and each reaction vessel contained both Phase I and Phase II biotransformation enzymes and co-factors to help catalyze the reactions. Pyrene was run as a positive control to ensure the enzymes were active and functional. A heat-inactivated negative control was run to ensure that any loss observed in the reaction vessel was due to biotransformation. In-vitro data are compared against measured dietary
bioaccumulation data in trout with the hopes to further our understanding of the role hepatic biotransformation has on bioaccumulation and the uncertainties or error that come with running extrapolation models. Additionally, the study hopes to better understand the differences between various species and their ability to metabolize xenobiotic compounds.
3.01.T-07 An Empirical Regression Model Based on Trout Liver S9 In Vitro Intrinsic Clearance and Log Kow to Predict Bioconcentration Factors in Fish
Heike Laue, Lu Hostettler and Andreas Natsch, Givaudan Schweiz AG, Switzerland
Bioaccumulation in aquatic species is a critical endpoint in the regulatory assessment of chemicals which usually involves the determination of the bioconcentration factor (BCF) in fish. The in vitro assay to determine in vitro intrinsic clearance (CLIN VITRO,INT) in liver S9 fractions (RT-S9) from rainbow trout (OECD TG 319B) has been validated to refine BCF predictions using in vitro-in vivo extrapolation (IVIVE) models. Although incorporation of measured in vitro clearance in IVIVE models does improve BCF predictions, a tendency for overprediction was shown for different chemicals. The goal of this study was to establish a regression model to predict BCFs based on empirical data. As training set, 40 chemicals, including 27 fragrance chemicals, with RT-S9 in vitro intrinsic clearance and in vivo BCFs determined in different fish species (OECD TG 305) were used. A simple regression model (log BCF= a × log Kow + b × log CLIN VITRO,INT) was built by estimating the parameters a and b by statistical fit based on in vivo BCFs, measured CLIN VITRO,INT in RT-S9 and log Kow. The regression analysis was performed with multiple datasets including species-matched subsets to evaluate the robustness of the estimation of the parameters a and b and the prediction of BCFs.Both parameters have a high statistical weight confirming the strong positive contribution of log Kow and the impact of the CLIN VITRO,INT to reduce the predicted BCF. A leave-one-out-analysis was performed on the training set. The predictions for the left-out chemicals using the respective 40 submodels are very similar to the predictions with the regression equation based on the complete training set indicating that the empirical regression model performs well. As an external test set for model validation, additional CLIN VITRO,INT were determined or taken from the literature for 20 chemicals with in vivo BCFs.
Geometric mean mispredictions (i.e. predicted BCF / in vivo BCF) of predicted BCFs with the regression equation were in the
same range or slightly lower compared to commonly applied IVIVE models. Species-matched regression models (n=18 for trout, n=21 for carp) did not result in significant improvements of BCF predictions. The empirical regression model could be used complementary to current IVIVE models to predict BCFs based on in vitro intrinsic clearance for bioaccumulation assessment and can overcome ambiguities such as the choice of the correct k1 estimation.
3.01.T-08 Investigating the Applicability of Laboratory Derived Toxicokinetics to the Field
Benedikt Lauper1, Eva Anthamatten2, Johannes Raths3, Dr. Maricor Jane Arlos4 and Juliane Hollender5, (1)Environmental Chemistry, Eawag, Swiss Federal Institute of Aquatic Science and Technology, Dübendorf, Switzerland, (2)Eawag, Swiss Federal Institute of Aquatic Science and Technology, Switzerland, (3)Uchem, Eawag, Zürich, Switzerland, (4)University of Alberta, Edmonton, AB, Canada, (5)Eawag - Swiss federal Institute of Aquatic Science and Technology, Switzerland
Knowledge on bioaccumulation and biotransformation of organic micropollutants are essential to link exposure to effect and to designate appropriate environmental quality standards. Bioaccumulation and biotransformation of organic micropollutants in aquatic organisms have been investigated in laboratory experiments extensively. For several micropollutants, especially pesticides, however, the measured internal concentrations in gammarids in field trials exceeded the predictions based on the laboratory data, sometimes by multiple orders of magnitude. In this work, we tested the applicability of laboratory derived toxicokinetic rate constants for caged gammarids deployed in a small Swiss stream known for high pesticide loads. Using an automated mobile LC-ESI-HRMS/MS system, the aqueous concentrations of 49 pesticides were measured at high temporal resolution throughout several rain events during the application season (every 20 min for 1 month). The water concentrations from this study were then employed to model the whole body concentration of gammarids using a one-compartment toxicokinetic model with toxicokinetic rate constants derived in an accompaning lab study. This data was then compared to the measured whole body concentration of the caged gammarids. Furthermore, the pesticide concentrations in the stream sediment, dietary source (leaves) as well as in suspended particles during rain events were measured and used to model their effect on the bioaccumulation of the pesticides. Our results show that the internal pesticide burden of gammarids is highly dynamic, with the aqueous exposure as the main influencing factor. While the laboratory derived toxicokinetic rate constants predicted the temporal trends in whole body concentrations reasonably well, the values were systematically underestimated over the whole time period. The highest underestimation occurred shortly after rain events with the model underestimating the pesticide concentrations by a factor of up to 31 ± 3.0. Finally, we demonstrated that while uptake from sediment does not contribute significantly to the total body burden even under worst case uptake assumptions, the suspended solids had considerably higher pesticide concentrations than the sediment and could explain the observed underestimation after rain events partially. Further possible reasons such as decreased
biotransformation under field conditions or concentration dependence of the toxicokinetics are currently explored.
3.01.T-09 Development & Testing of an In-Vitro S9 Rat Liver Bioassay for Assessing Biotransformation Rates of Neutral Hydrophobic Organic Chemicals in Air-Breathing Organisms of Terrestrial Food-Webs
Frank Gobas1, Yung-Shan Lee2, Talia Cole1, Manpreet Jhutty1, Beatrice Chee1, Stephanie Stelmachuk1 and Mark Cantu1, (1)Simon Fraser University, Canada, (2)Simon Fraser Univeristy, Canada
In vitro biotransformation assays combined with in vitro-in vivo extrapolation (IVIVE) is a relatively novel approach to bioaccumulation assessments that can reduce cost, effort, time and animal testing and accelerate the assessment process. The Organization for Economic Co-operation and Development (OECD) has developed test guidelines 319B to determine in vitro biotransformation rates in fish using liver S9 of rainbow trout. However, similar protocols are not available for mammalian bioaccumulation assessments and in vitro liver S9 data for neutral hydrophobic substances with a high bioaccumulation potential in air-breathing organisms are largely unavailable. The objective of this study is to develop and test a refined protocol for in-vitro testing of biotransformation rates in rats using rat liver S9 that might be useful for bioaccumulation screening of neutral
hydrophobic organic chemicals in air-breathing organisms. The framework has 4 components, including (a) S9 preparation and characterization, (b) preliminary experiments to optimize test conditions, (c) final experiments with multiple independent tests to determine in vitro biotransformation rates in a standardized way, and (d) analysis of assay results for bioaccumulation screening.
The refined protocol was tested and evaluated using 14 test chemicals with a variety of chemical structures and biotransformation capacities. In vitro biotransformation rate constants (kr) were measured and extrapolated to whole organism biotransformation rate constants (kmet) using 4 previously reported IVIVE models. Lipid-normalized biomagnification factors (BMFL) were then
calculated using a rat bioaccumulation model. The calculated total elimination rates were compared to available in vivo data. The results indicate that (a) measured in vitro depletion rates were highly reproducible in independent tests; (b)extrapolated whole organism biotransformation rates were similar among various IVIVE models; (c) calculated total elimination rate constants were in good agreement with reported in vivo data; and (d) application of the developed methodology shows that a substance is not expected to biomagnify in rats (i.e., BMFL < 1) when in vitro kr ? 0.3 h-1 in rat liver S9. However, poorly metabolizable substances with an in vitro kr < 0.3 h-1 in rat liver S9 are not expected to biomagnify if they have a low log KOA (< 5), or a very low or very high log KOW (< 1 or >9), or exhibit a low dietary uptake efficiency (< 5%).
3.01.T-10 Poster Spotlight [3.01.P-Mo099 | PS2 | PS3]
Visit the poster session for abstracts
3.01 Advances in Bioaccumulation Science and Assessment (Virtual Only)
3.01.V-01 Efficiency of Varied Xenobiotic Detoxification Biomarkers in Highlighting the Exposure of Daphnia magna to an Organophosphate Pesticide
Elodie Melo de Almeida, Floriane Tisserand and Nathalie Chevre, University of Lausanne, Switzerland
Freshwaters are among the most stressed ecosystems worldwide. Their increased overexploitation generates various anthropogenetic stressors for living organisms. Among others, one stressor is the pollution by chemicals. Aquatic
macroinvertebrates play an important role in aquatic food webs and are highly sensitive to chemicals. They can therefore be used as sentinel organisms for highlighting the deleterious effects of these compounds. The study of the biomarkers induced in these organisms is of great interest for assessing the effects of low and chronic concentrations of compounds. In this study, we aim in finding out the most sensitive detoxification biomarker in Daphnia magna as a potential candidate for laboratory and in situ ecotoxic assessment. Cytochrome P450 system mostly operates in first step xenobiotic detoxification in aquatic invertebrates. The ability to measure this mixed function oxidase activity allows in understanding responses to chemical stressors. However, existing measurement of cytochrome P450 activities research for aquatic macroinvertebrates is limited with patchy and variable success.
Our study is investigating several P450 biomarkers occurring during a process of detoxification on D. magna. Present work improves knowledge about P450 enzymatic biomarkers, specificity and accuracy to D. magna exposed to organophosphate chemicals and finally empowers determination level of aquatic microinvertebrates’ exposition to chemicals. Indeed, comparing and testing methodologies in laboratory is a crucial previous work for highlighting effects in the field. The main objective of the present work was therefore to test diverse cytochrome P450 enzymatic biomarkers (EROD, MROD, ECOD, APND and ERND) and to establish a suitable methodology for aquatic macroinvertebrates. Furthermore, our study investigated P450 biomarkers signal detection function of exposure time with the aim of understanding xenobiotic detoxification pattern through time. First, we tested these 5 biomarkers in Daphnia magna exposed for 5 days at 9 different concentrations of an organophosphate pesticide (diazinon). EROD, ECOD and APND showed a higher sensitivity. Secondly, we tested selected biomarkers, EROD, ECOD and APND in D. magna exposed for 1 to 5 days. Results are currently being analyzed.
3.01.V-02 Evaluating the Long-Term Toxicity and Bioaccumulation of Gold Nanobiomaterials in Fish
David Hernandez-Moreno1, Rocío Fernández-Saavedra2, Ana I. Cardona-García2, Isabel Rucandio2 and Maria Luisa
Fernandez-Cruz3, (1)INIA, Spain, (2)CIEMAT, Spain, (3)Environment and Agronomy, INIA - National Institute for Agricultural and Food Research and Technology, Madrid, Spain
Nanobiomaterials (NBMs) are receiving much attention because of their application in biomedical devices. However, their production and use also imply the risk of delivery to the environment. The aim of the present study was to evaluate the potential effects of gold nanoparticles (Au NP) in Oncorhynchus mykiss after long-term exposure via water. Effects were evaluated at two levels, the growth effect in juveniles (OECD TG215) and the Au bioaccumulation in fish and fish tissues (OECD TG305). Au NP (5-20 nm) with citrate as capping agent and spherical shape was supplied by Colorobbia Consulting SRL (Italy) as a liquid stock suspension. Working solutions (growth: 0, 0.05, 0.15, 0.5, 1.5, and 5 mg/L; bioaccumulation: 0, 0.5 and 5 mg/L) were prepared by direct pipetting of the stock in aquarium water. Water was renewed every two days. The exposure period lasted for 28 days in both assays, followed by a depuration phase of 14 days (water without NBM). For the growth assay, 9 fish were weighted at the beginning of the experiment and introduced in each aquarium (6 in total). Fish were weighted and fed at a ration of 4% body weight/day. Animals were weighted again after 14 days and at the end of the exposure. Tissues were frozen at -80ºC to study different markers of toxicity. For the bioaccumulation (minimized test) assay 3 aquaria were used with 16 fish each. Four fish were sampled at time 0, 14 and 28 days of exposure and time 7 and 14 of depuration. Carcass and tissues (liver, gills, intestine, stomach and muscle) were digested using aqua regia, Au was analysed by ICP-MS. The differences between the measured and the nominal concentrations of Au in water were lower than 20 %. There were no effects on the fish welfare, neither significant differences in growth among groups. The possible sublethal effects are still under study. Au levels could be measured in different tissues at the two exposure levels. There was a reduction in Au levels in the whole body after 7 days of depuration with a
complete elimination after 14 days. Muscle was not a tissue target of Au, but gills, stomach and intestine showed to be the principal receptors and accumulated the biggest ammount of metal, followed by liver. After 14 days of depuration, gills and liver still showed high levels of Au. In conclusion 14 days of depuration were not long enough to assure the complete elimination of Au from gills and liver at the two exposure levels. Acknowledgement – H2020 project BIORIMA 760928
3.01.V-03 The Effect of Sulfidation and Soil Type on the Uptake of Silver Nanoparticles in Enchytraeus crypticus Ms. Zahra Khodaparast1, Susana Loureiro2, Rudo A. Verweij3 and Cornelis A.M. (Kees) van Gestel3, (1)University of Aveiro, Portugal, (2)Universidade de Aveiro, Portugal, (3)Vrije Universiteit Amsterdam, Netherlands
AgNPs are used in a wide range of daily products leading to their emission to waste water treatment plants (WWTP). Due to the presence of a large proportion of sulfide and the reduced conditions during wastewater treatment, Ag2S is expected to be formed from Ag ions or AgNPs. The application of sewage sludge on agricultural land triggers concerns about exposure of terrestrial organisms to pristine or sulfidized AgNPs. Therefore, hazard assessment must be accurately performed. This study determined the uptake and elimination kinetics in Enchytraeus crypticus of different Ag forms: paraffin-coated 3–8 nm, PVP-coated 50 nm, and 60 nm AgNPs, 20 nm Ag2S NPs PVP-coated and AgNO3. The Ag2S NPs were synthetized to simulate aged AgNPs after passing through a WWTP, while the other NPs were tested as manufactured. To assess the effect of soil type on the bioavailability and uptake of the Ag2S NPs as the most environmentally relevant Ag species, animals were exposed through three different soils, Dorset, Woburn, and Lufa 2.2 (the same was carried out for AgNO3). In all tests, E. crypticus was exposed to soil spiked at 10 mg Ag kg-1 dry soil for 14 days and then transferred to clean soil for a 14-day elimination phase. During both phases, animals were sampled from three replicate jars on days 1, 2, 4, 7, 9, 11, and 14, kept overnight to purge their gut and frozen (-20 ?C), dried, digested and analysed for Ag by graphite furnace Atomic Absorption Spectrophotometry. A first-order one-compartment kinetics
model was used to describe Ag accumulation in the animals. The uptake rate constants were similar for 3–8 nm and 60 nm AgNPs and AgNO3, but significantly different between 3–8 nm and 50 nm AgNPs, so, Ag bioavailability was influenced by its form and characteristics. Uptake and elimination rate constants of Ag significantly differed between the test soils. For Ag2S NPs the Ag uptake and elimination rate constants were significantly lower for Dorset than for Woburn and with no significant differences between the estimated kinetics for Lufa 2.2 compared to the other two soils. For AgNO3, significantly higher uptake and
elimination rate constants in enchytraeids were found in the sandy and acid Dorset soil compared to the other soils. Therefore, soil properties affect the bioavailability of Ag directly and bioaccumulation indirectly by affecting the transformation and distribution of Ag in soil and pore water. The kinetics of Ag2S NPs cannot be predicted by those of AgNO3.
3.01 Advances in Bioaccumulation Science and Assessment (Poster)
3.01.P-Mo094 Sorption of Three Pesticides to the Seaweeds Ulva Lactuca and Sargassum muticum
Bas Buddendorf1, Arrienne Matser2, Wim Beltman2 and Ivo Roessink2, (1)Wageningen UR, Nederland, (2)Wageningen Environmental Research, Netherlands
Seaweed receives more and more global attention as a driver of a blue economy. It has the potential to deliver more food to an increasing world population and can provide basic ingredients for medicine, cosmetics, and even fuel. As a result, seaweed is being cultured in estuaries, open seas, or ponds. Seaweed grows best under nutrient-rich productive circumstances but here exposure to contaminants, such as pesticides, is likely. Depending on their hydrophobicity, an association of pesticides with seaweeds can occur. Although potentially problematic for some commercial uses, this also presents the possibility to use seaweed for remediation of effluent water from the pond- or tank-based aquaculture systems. To be able to predict associated
(environmental) risks, we recommend extending existing models (e.g. the ERA-AQUA model) with a seaweed compartment. In order to assess seaweed-pesticide interactions, so-called sorption coefficients are required. Unfortunately, there is a general lack of sorption, uptake, bioaccumulation, and effects studies under laboratory conditions for seaweed species. In order to fill part of this data gap, a study on the sorption of three pesticides to the seaweeds U. lactuca and S. muticum was performed using a batch method according to OECD-106 at one concentration level. Three pesticides were selected to cover a representative range of expected sorption behavior, using sorption to the organic matter in soil Kom as a determinant. The Kom values of Thiamethoxam, Diazinon, and Chlorpyrifos are 33, 353, and 2072 L/kg, respectively. Results of the sorption experiments will be presented. In future work, the pesticide sorption coefficients determined for seaweeds can be used in risk assessment by extending existing models like ERA-AQUA with a seaweed compartment to calculate pesticide content of seaweed and pesticide concentrations in the pond or tank water and in effluent released from aquaculture systems.
3.01.P-Mo095 Trophic Magnification of Perfluoroalkyl Substances Within a Terrestrial Avian Food Web
Kate Fremlin1, Dr. John E. Elliott2, Robert J. Letcher3, Tom Harner4, Anita Eng4 and Frank Gobas5, (1)Simon Fraser University, Burnaby, BC, Canada, (2)Research Scientist, Environment and Climate Change Canada, Canada, (3)Science and Technology Branch, Environment and Climate Change Canada, Ottawa, ON, Canada, (4)Environment and Climate Change Canada, Canada, (5)Simon Fraser University, Canada
The primary endpoints and criteria currently used in North America to define a substance as bioaccumulative include log octanol-water partition coefficients (log KOW) >5 and/or bioconcentration or bioaccumulation factors (BCF or BAF) >5,000. However, these endpoints limit our ability to identify substances that may be bioaccumulative in air-breathing organisms or terrestrial ecosystems since they do not account for chemical exposure from air or in air-breathing organisms. In addition, these endpoints, particularly KOW, are not suitable for understanding the bioaccumulation potential of perfluoroalkyl substances (PFAS) within terrestrial systems because KOW cannot be reliably measured for ionic surfactants. To establish effective guidelines that protect terrestrial species, there is a need to further investigate the bioaccumulation process of PFAS in terrestrial organisms. Thus, we assessed biomagnification of a suite of PFAS [all perfluoroalkyl acids (PFAAs)] in an urban terrestrial food-web that included an avian apex predator, the Cooper’s hawk (Accipiter cooperii). We analysed samples of Cooper’s hawk eggs, songbirds,
invertebrates, soil, and air samples for concentrations of PFAAs. Each organism sample was analysed for protein and
phospholipid content to account for differences in sorbing matrices. Using stable isotope analysis of ?13C and ?15N signatures, we estimated the trophic position of each organism. Trophic Magnification Factors were determined using three approaches: 1) wet weight concentrations (TMFW); 2) concentrations normalized based on tissue composition in each organism (i.e., protein, lipid, and phospholipid; TMFN); and 3) concentrations expressed as thermodynamic activities (TMFA). TMFWs of PFAAs ranged from 0.75 to 6.8 and TMFNs ranged from 0.81 to 7.5, indicating that most PFAAs are biomagnifying in this urban terrestrial system.
3.01.P-Mo096 A Generic Model Based on the Properties of Nanoparticles and Cells for Predicting Cellular Uptake Ms. Bingqing Lu1, Prof. Jan A.J. Hendriks2 and Tom Nolte3, (1)Department of environmental science, Radboud University, Nijmegen, Netherlands, (2)Radboud University Nijmegen, Nijmegen, Netherlands, (3)Radboud University Nijmegen, Netherlands Nanoparticles (NPs) are widely used in industry and technology due to their small size and versatility, which makes them easy to enter organisms and pose threats to human and ecological health. Given the particularity and complex structure of NPs, statistical models alone cannot reliably predict uptake. Hence, we developed a generic model for predicting the cellular uptake of NPs with organic coatings, based on physicochemical interactions underlying uptake. The model utilized the concentration, experimental conditions and properties of NPs viz. size, surface coating and coverage. These parameters were converted to surface energy components and surface potentials, and combined with the components and potential for a cell membrane. For NPs uptake, we constructed energetic profiles and barriers for adsorption and permeation onto/through cell membranes. The relationships derived