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The goal of the current study was to quantify the trophic transfer of copper nanoparticles (CuNPs) in a food chain consisting of the microalga Pseudokirchneriella subcapitata as the representative of primary producer, the grazer Daphnia magna, and the omnivorous mysid Limnomysis benedeni. To quantify the size and number concentration of CuNPs in the biota, tissue extraction with tetramethylammonium hydroxide (TMAH) was performed and quantification was done by single particle inductively coupled plasma mass spectrometry (sp-ICP-MS). The bioconcentration factor (BCF) of the test species for CuNPs varied between 102 – 103 L/kg dry weight when expressing the internal concentration on a mass basis, which was lower than BCF values reported for Cu2+ (103 – 104 L/kg dry weight). The particle size of CuNPs determined by sp-ICP-MS ranged from 22 to 40 nm in the species. No significant changes in the particle size were measured throughout the food chain. Moreover, the measured number of CuNPs in each trophic level was in the order of 1013 particles/kg wet weight. The calculated trophic transfer factor (mass concentration basis) was > 1. This indicates biomagnification of particulate Cu from P. subcapitata to L. benedeni. It was also found that the uptake of particulate Cu (based on the particle number concentration) was mainly from the dietary route rather than from direct aqueous exposure. Furthermore, dietary exposure to CuNPs had a significant effect on the feeding rate of mysid during their transfer from daphnia to mysid and from alga through daphnia to mysid. This work emphasizes the importance of tracing the particulate fraction of metal-based engineered nanoparticles when studying their uptake and trophic transfer.

The use of copper oxide (CuO) NPs results in the release of these particles into the aquatic environment. Here, the particles settle out and accumulate in the sediment. However, little is known about the biodynamics of sediment-associated NPs in benthic organisms. We compared the toxicity and biodynamics of CuO NPs (7 nm) and dissolved Cu (CuCl2) in the sediment-dwelling oligochaete, Tubifex tubifex, to gain insights into the relative importance of metal form (CuCl2 vs CuO NPs) and exposure route (water vs sediment). Isotopically enriched 65Cu was used as a tracer to distinguish background from newly accumulated 65Cu in worms. For each exposure route, we conducted three experiments: one uptake, one elimination, and one longer-term net accumulation experiment to parameterize uptake and elimination of 65CuCl2 and 65CuO NPs in T. tubifex. 65Cu accumulation was detected for both 65CuCl2 and 65CuO NPs regardless of whether T. tubifex were exposed in sediment- or water-only setups. Water exposures to 65CuCl2 resulted in tail trauma whereas limited effects were seen for sediment exposures or exposures to 65CuO NPs via either exposure route. Uptake rate constants and accumulation of 65Cu in T. tubifex were higher following 65CuCl2 exposure than 65CuO NPs, in water, but not in sediment. Thus, the relative importance of exposure route and Cu form for uptake dynamics is not straightforward suggesting that findings on bioaccumulation and toxicity in water exposures cannot be directly extrapolated to sediment. [ABSTRACT FROM AUTHOR]

Benzo[a]pyrene (BaP) and cadmium (Cd) are soil pollutants that persist in the environment and impacting soil health. Earthworms are selective consumers, yet little is known about how their feeding and burrowing habits translate into species-specific differences in pollution accumulation and distribution. Here, we exposed three ecophysiologically distinct earthworm species, Eisenia fetida (epigeic), Pheretima guillelmi (endogeic), and Metaphire guillelmi (anecic) to different concentrations (0, 1, 10, 30, 60, 100, 300, 500 mg/kg) of BaP or Cd in natural fluvo–aquic soil for 14 days. BaP and Cd accumulation and distribution patterns were analyzed at the individual and organ levels. The results showed that the adsorption behavior of BaP or Cd in earthworms and the organs fit the Langmuir adsorption model well (R 2  > 0.8, p  < 0.001). E. fetida and M. guillelmi accumulated more BaP than Cd, with the respectively higher predicted maximum internal concentration (C max ) of BaP (1946.27 ± 306.29 mg/kg, 2046.61 ± 90.64 mg/kg) and the lower C max of Cd (279.75 ± 49.57 mg/kg, 318.11 ± 60.64 mg/kg), while P. guillelmi showed the opposite trend with 927.10 mg/kg of Cd C max and 358.82 ± 68.35 mg/kg of BaP C max . The low mobility of endogeic worms may reduce their BaP accumulation, and lead to a lower BaP bioaccumulation factor (BAF) than that observed for the other two earthworms; P. guillelmi had a BAF of 8.64 ± 1.79, which was far less than that of E. fetida (106.93 ± 11.84) and M. guillelmi (350.16 ± 67.15). Whereas the higher Cd accumulation in P. guillelmi may be due to their highly efficient geophagous feeding strategy, at the same time the highest Cd BAF achieved (e.g. 203.54 ± 19.96 under 1 mg/kg Cd exposure). BaP distributed mainly in the body walls of all three earthworms (average 60.78%), as its high hydrophobicity increased its dermal uptake. More BaP than Cd accumulated in the reproductive organs, and C max of BaP in E. fetida , P. guillelmi, and M. guillelmi in the reproductive organs was 4031.08 ± 1237.38 mg/kg, 490.76 ± 79.88 mg/kg, and 3675.24 ± 794.68 mg/kg, respectively. However, Cd was more abundant in the gizzard and gut, as its hydrophilic nature meant Cd was mainly ingested orally, and the C max of Cd in E. fetida , P. guillelmi, and M. guillelmi in the gizzard and gut, respectively, was 452.43 ± 48.33 and 360.83 ± 44.36 mg/kg, 996.03 and 809.11 mg/kg, and 93.37 and 109.19 mg/kg. By contrast, for E. fetida , more Cd was distributed in the body wall (average 50.16%), possibly due to its high affinity for this organ (the average logK L for the body wall was −3.60) predicted by the Langmuir adsorption model, also the worm ingested less soil. These data suggest that ecotype influences the accumulation and distribution of pollutants in earthworms, as their ecophysiological properties (e.g., motility, food choices, and feeding efficiency) affect their exposure to and ingestion of pollutants. The distinct chemical properties of BaP and Cd also appear to affect their accumulation and distribution in earthworms. These factors should be considered when using earthworms as bioindicators in environmental risk assessments. [ABSTRACT FROM AUTHOR]

In ecotoxicology, it is continuously questioned whether (nano)particle exposure results in particle uptake and subsequent biodistribution or if particles adsorb to the epithelial layer only. To contribute to answering this question, we investigated different uptake routes in zebrafish embryos and how they affect particle uptake into organs and within whole organisms. This is addressed by exposing three different life stages of the zebrafish embryo in order to cover the following exposure routes: via chorion and dermal exposure; dermal exposure; oral and dermal exposure. How different nanoparticle sizes affect uptake routes was assessed by using polystyrene particles of 25, 50, 250 and 700 nm. In our experimental study, we showed that particle uptake in biota is restricted to oral exposure, whereas the dermal route resulted in adsorption to the epidermis and gills only. Ingestion followed by biodistribution was observed for the tested particles of 25 and 50 nm. The particles spread through the body and eventually accumulated in specific organs and tissues such as the eyes. Particles larger than 50 nm were predominantly adsorbed onto the intestinal tract and outer epidermis of zebrafish embryos. Embryos exposed to particles via both epidermis and intestine showed highest uptake and eventually accumulated particles in the eye, whereas uptake of particles via the chorion and epidermis resulted in marginal uptake. Organ uptake and internal distribution should be monitored more closely to provide more in depth information of the toxicity of particles. [ABSTRACT FROM AUTHOR]

Engineered nanoparticles released into surface water may accumulate in sediments, potentially threatening benthic organisms. This study determined the toxicokinetics in Chironomus riparius of Ag from pristine silver nanoparticles (Ag NPs), a simulating aged Ag NP form (Ag 2 S NPs), and AgNO 3 as an ionic control. Chironomid larvae were exposed to these Ag forms through water, sediment, or food. The potential transfer of Ag from larvae to adult midges was also evaluated. Results revealed higher Ag uptake by C. riparius upon exposure to Ag 2 S NPs, while larvae exposed to pristine Ag NPs and AgNO 3 generally presented similar uptake kinetics. Uptake patterns of the different Ag forms were generally similar in the tests with water or sediment exposures, suggesting that uptake from water was the most important route of Ag uptake in both experiments. For the sediment bioaccumulation test, uptake was likely a combination of water uptake and sediment particles ingestion. Ag uptake via food exposure was only significant for Ag 2 S NPs. Ag transfer to the terrestrial compartment was low. In our environmentally relevant exposure scenario, chironomid larvae accumulated relatively high Ag concentrations and elimination was extremely low in some cases. These results suggest that bioaccumulation of Ag in its nanoparticulate and/or ionic form may occur in the environment, raising concerns regarding chronic exposure and trophic transfer. This is the first study determining the toxicokinetics of NPs in Chironomus, providing important information for understanding chironomid exposure to NPs and their potential interactions in the environment., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022. Published by Elsevier B.V.)

The bioaccumulation of nanoplastics (NPs) has been intensively examined using the fluorescence-labeling technique. As the fluorescence intensity per particle is different for NPs with different physicochemical properties, it's hard to directly compare their bioaccumulation based on fluorescence. Therefore, how physicochemical properties may affect NPs' bioaccumulation remains unclear. In the present study, we chose polystyrene NPs (PSNPs) with the primary particle size of 70 nm (PS 70), 200 nm (PS 200), and 500 nm (PS 500), and examined their uptake by human lung and intestine cells. We found that PSNPs had low cytotoxicity, but could be taken up by both cell lines. The particle-mass-, particle-number-, and particle-surface-area-based accumulation of the differently-sized PSNPs were then compared. Smaller PSNPs showed lower particle-mass-based but higher particle-number-based uptake rate than the larger ones. Nevertheless, much less difference was observed when the unit of uptake rate was based on particle surface area, suggesting the critical role of surface area during PSNPs' interaction with the cell membrane. Additionally, all three PSNPs could enter the cells by phagocytosis and PS 70 could also be internalized by clathrin- and caveolae-mediated endocytosis. Overall, the effects of size on the bioaccumulation of NPs need to be considered when evaluating their environmental and health risks. [Display omitted] • PSNPs of different sizes can be taken up by both lung and intestine cells. • Particle-mass-based uptake rate increased with PSNP size. • Particle-number-based uptake rate decreased with PSNP size. • Much less difference was found for the particle-surface-area-based uptake rate. • PSNPs of different sizes were taken up through different endocytosis routes. [ABSTRACT FROM AUTHOR]

The goal of the current study was to quantify the trophic transfer of copper nanoparticles (CuNPs) in a food chain consisting of the microalga Pseudokirchneriella subcapitata as the representative of primary producer, the grazer Daphnia magna, and the omnivorous mysid Limnomysis benedeni. To quantify the size and number concentration of CuNPs in the biota, tissue extraction with tetramethylammonium hydroxide (TMAH) was performed and quantification was done by single particle inductively coupled plasma mass spectrometry (sp-ICP-MS). The bioconcentration factor (BCF) of the test species for CuNPs varied between 102 – 103 L/kg dry weight when expressing the internal concentration on a mass basis, which was lower than BCF values reported for Cu2+ (103 – 104 L/kg dry weight). The particle size of CuNPs determined by sp-ICP-MS ranged from 22 to 40 nm in the species. No significant changes in the particle size were measured throughout the food chain. Moreover, the measured number of CuNPs in each trophic level was in the order of 1013 particles/kg wet weight. The calculated trophic transfer factor (mass concentration basis) was > 1. This indicates biomagnification of particulate Cu from P. subcapitata to L. benedeni. It was also found that the uptake of particulate Cu (based on the particle number concentration) was mainly from the dietary route rather than from direct aqueous exposure. Furthermore, dietary exposure to CuNPs had a significant effect on the feeding rate of mysid during their transfer from daphnia to mysid and from alga through daphnia to mysid. This work emphasizes the importance of tracing the particulate fraction of metal-based engineered nanoparticles when studying their uptake and trophic transfer. [Display omitted] • Bioconcentration factor of test species for CuNPs was found to be lower than Cu2+. • Particle size of CuNPs determined by sp-ICP-MS ranged from 22 to 40 nm in species. • No significant changes in the particle size of CuNPs were measured during uptake. • Biomagnification of particulate Cu occurred from alga to mysid. • Uptake of particulate Cu was mainly from dietary route not direct aqueous exposure. [ABSTRACT FROM AUTHOR]

Abstract: Perfluoroalkyl acids (PFAs), one kind of emerging contaminants, have attracted great attentions in recent years. However, the study about their bioaccumulation mechanism remains scarce. In this research, the bioaccumulation of six kinds of PFAs in water flea Daphnia magna was studied. The uptake rates of PFAs in D. magna ranged from 178 to 1338Lkg−1 d−1, and they increased with increasing perfluoroalkyl chain length; the elimination rates ranged from 0.98 to 2.82d−1. The bioaccumulation factors (BAFs) of PFAs ranged from 91 to 380Lkg−1 in wet weight after 25d exposure; they increased with increasing perfluoroalkyl chain length and had a significant positive correlation with the n-octanol/water partition coefficients (log K ow) of PFAs (p <0.05). This indicated that the hydrophobicity of PFAs plays an important role in their bioaccumulation. The BAFs almost kept constant when the PFA concentrations in aqueous phase increased from 1 to 10μgL−1. Scenedesmus subspicatus, as the food of D. magna, did not significantly affect the bioaccumulation of PFAs by D. magna. Furthermore, the body burden of PFAs in the dead D. magna was 1.08–2.52 times higher than that in the living ones, inferring that the body surface sorption is a main uptake route of PFAs in D. magna. This study suggested that the bioaccumulation of PFAs in D. magna is mainly controlled by their partition between organisms and water; further research should be conducted to study the intrinsic mechanisms, especially the roles of protein and lipid in organisms. [Copyright &y& Elsevier]

Abstract: Traditionally in toxicological studies time is not studied as quantifiable variable but as a fixed endpoint. The Reduced Life Expectancy (RLE) model which relates exposure time and exposure concentration with lethal toxic effects was tested previously using fish data. In this current paper the effects of exposure time on aquatic toxicity with zooplanktons and various toxicants were evaluated using the RLE model based on ambient exposure concentration. The model was evaluated by plotting ln LT 50 against LC 50 using toxicity data with zooplanktons from the literature for metal, metalloid and organic compounds. Most of the experimental data sets can be satisfactorily correlated by use of the RLE model, but deviations occurred for some data sets. Those data sets were satisfactorily fitted by a two stage RLE model. This model was based on two phases: one in the peripheral system and other in the central system. Both the single and two stage RLE model support the hypothesis that toxicity is time dependent and decreases in a systematic way with increasing exposure time. A calculated normal life expectancy (NLT) can be obtained from the single stage model and is in accord with reported NLT but those obtained from the two stage RLE model are in excellent agreement. [Copyright &y& Elsevier]

Instar V larvae of the aquatic insect Stenopsyche marmorata were transferred between a noncontaminated site and a contaminated site and changes in the accumulation of nickel (Ni), copper (Cu), zinc (Zn), and lead (Pb) in larvae were monitored for 30 days. Concentrations of the four metals rapidly increased or decreased within 10 days in the transferred larvae and approached concentrations of the native larvae living in the transfer sites. The accumulation of Ni and Cu in the larval body was very noticeable. The decreased Ni concentrations are represented by two exponential rate formulas, suggesting a biological half-life of 1.4 and 12.1 days. Under laboratory conditions, routes of Ni and Cu uptake were examined and Ni uptake was found to be mainly from food. However, larvae accumulated Cu from both food and water sources. In this case, the amount of metal uptake from food was more than that from water. The results of this indoor experiment are discussed and compared with the results of the transfer field experiment. Active biomonitoring of trace metal in transferred larvae is useful since it enables rapid and easy assessment of metal contamination. [Copyright &y& Elsevier]

The use of copper oxide (CuO) NPs results in the release of these particles into the aquatic environment. Here, the particles settle out and accumulate in the sediment. However, little is known about the biodynamics of sediment-associated NPs in benthic organisms. We compared the toxicity and biodynamics of CuO NPs (7 nm) and dissolved Cu (CuCl 2 ) in the sediment-dwelling oligochaete, Tubifex tubifex , to gain insights into the relative importance of metal form (CuCl 2 vs CuO NPs) and exposure route (water vs sediment). Isotopically enriched 65 Cu was used as a tracer to distinguish background from newly accumulated 65 Cu in worms. For each exposure route, we conducted three experiments: one uptake, one elimination, and one longer-term net accumulation experiment to parameterize uptake and elimination of 65 CuCl 2 and 65 CuO NPs in T. tubifex . 65 Cu accumulation was detected for both 65 CuCl 2 and 65 CuO NPs regardless of whether T. tubifex were exposed in sediment- or water-only setups. Water exposures to 65 CuCl 2 resulted in tail trauma whereas limited effects were seen for sediment exposures or exposures to 65 CuO NPs via either exposure route. Uptake rate constants and accumulation of 65 Cu in T. tubifex were higher following 65 CuCl 2 exposure than 65 CuO NPs, in water, but not in sediment. Thus, the relative importance of exposure route and Cu form for uptake dynamics is not straightforward suggesting that findings on bioaccumulation and toxicity in water exposures cannot be directly extrapolated to sediment.

Delineation of metal uptake routes in aquatic invertebrates is critical for characterizing bioaccumulation dynamics and assessing risks associated with metal exposure. Here we demonstrate that Cu stable isotopic ratios can be manipulated in both exposure media and algae to determine the efflux rate constant (ke) and to estimate Cu assimilation efficiency (AE) from ingested food in a freshwater bivalve (Corbicula fluminea). The Cu AE in Corbicula fed 65Cu-spiked Cryptomonas ozolini was 38%. Copper uptake routes had no significant influence on efflux; ke of 0.004 per day characterized the slowest component of efflux following short-term exposures to 65Cu in water or in both food and water. Incorporation of the physiological parameters for dietary and dissolved uptake as well as rate constants of loss into a bioaccumulation model allowed for assessing the relative contribution of water and food as Cu sources. At [65Cu2+] of 6.7 µg/L, Corbicula accumulated twice as much Cu from diet as from water. In most freshwater systems, the dietary pathway is likely to act as the major Cu uptake route for Corbicula. Extrapolation of our laboratory results to the San Francisco Bay-Delta (California, USA) indicated that our biodynamic model and the laboratory-derived parameters for dietary 65Cu uptake provided a realistic representation of the processes involved in Cu accumulation by the bivalve Corbicula. [ABSTRACT FROM AUTHOR]