Increasing applications of titanium dioxide nanoparticles (nano-TiO2) have intensified the risk of environmental contamination. Since nano-TiO2 can absorb metals and be consumed as ‘food’ by ...zooplankton but also can interact with phytoplankton, they could significantly disturb the existing metal assimilation patterns. In the present study, we quantified the dietary assimilation of Cd and Zn from nano-TiO2 and algae (Chlamydomonas reinhardtii) at comparable particle concentrations as well as in complex food environment (variable food quality and quantity) in a freshwater zooplankton Daphnia magna using the radiotracer technique. For both nano-TiO2 and algae as food, the feeding food quality and depuration food quantity significantly affected the assimilation efficiencies (AEs) of Cd and Zn. At feeding food quantity of 1 mg/L to 10 mg/L without food in depuration, the AEs of Cd and Zn from nano-TiO2 were lower than those from algae. When food was added during depuration, the influences of nano-TiO2 on metal AEs were variable due to the differential effects of food quantity on the gut passage of nano-TiO2 and algae. Furthermore, mixed nano-TiO2 and algae had the lowest metal AEs compared to sole nano-TiO2 or algae as a result of interaction between nano-TiO2 and algae during feeding. Overall, this study showed the distinguishing metal AEs between nano-TiO2 and algae, and that nano-TiO2 could significantly reduce the existing metal AEs from algae. More attention should be paid to the potential roles of nano-TiO2 in disturbing metal assimilation in the environmental risk assessments of nanoparticles.
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•Distinguishing metal assimilation from nano-TiO2 and algae by Daphnia.•Nano-TiO2 could significantly reduce the existing metal AEs from algae.•Feeding food quality and depuration food quantity affected the metal assimilation.•More attention on nano-TiO2 in disturbing metal assimilation in environmental risk assessments.
Metal assimilation in daphnids differed between nano-TiO2 and algae and nano-TiO2 could significantly reduce the existing metal assimilation from algae.
Abstract A number of reports on potential toxicity of nanoparticles are available, but there is still a lack of knowledge concerning bioaccumulation. The aim of this work was to investigate how ...different sources of zinc, such as uncoated and unmodified ZnO nanoparticles, ZnCl2 in solution, and macropowder ZnO influence the bioaccumulation of this metal in the terrestrial isopod Porcellio scaber. After exposure to different sources of Zn in the diet, the amount of assimilated Zn in whole body, the efficiency of zinc assimilation, and bioaccumulation factors (BAFs) were assessed. The bioaccumulation potential of Zn was found to be the same regardless of Zn source. The amount of assimilated Zn and BAF were dose-dependent, and Zn assimilation efficiency was independent of exposure concentrations. The Zn assimilation capacity was found to be up to 16% of ingested Zn. It is known that as much as approximately 20% of Zn can be accreted from ZnO particles by dissolution. We conclude that bioaccumulation of Zn in isopods exposed to particulate ZnO depends most probably on Zn dissolution from ZnO particles and not on bioaccumulation of particulate ZnO.
Feeding ratio and frequency have substantial effects on food digestion and assimilation in fish, yet few attempts have been made to determine their influences on the bioaccumulation of trace metals. ...In this study, juvenile Acanthopagrus schlegeli were exposed to either waterborne or dietary cadmium (Cd) at different feeding ratios (0, 2, or 4% body weight d⁻¹ BW d⁻¹ under waterborne Cd exposure and 1, 2.5, or 4% BW d⁻¹ under dietary Cd exposure) or feeding frequencies (1, 2 or 8 times d⁻¹) for 5 wk. Under waterborne Cd exposure, the fish fed 0% BW d⁻¹ or 8 times d⁻¹ showed significantly lower growth rates and those fed 0% BW d⁻¹ or 1 time d⁻¹ exhibited higher Cd body burdens and Cd uptake rates compared to the other groups. The gut showed a significantly higher waterborne Cd uptake rate than the gills when fish were fasted or fed only 1 time d⁻¹. These results suggest that starvation and low feeding frequency facilitate waterborne Cd uptake. Under dietary Cd exposure, the fish fed 4% BW d⁻¹ or 2 times d⁻¹ grew faster. Cd body burden and Cd assimilation were higher in fish fed 2.5% BW d⁻¹ or 2 times d⁻¹. Dietary Cd retention was positively correlated with feed efficiency, suggesting the utilization of Cd probably coincides with the essential nutrients in fish. Overall, this study demonstrates that different feeding strategies significantly influence waterborne and dietary Cd bioaccumulation in marine fish. Therefore, feeding conditions have to be considered carefully for managing trace metal contamination in marine fish farming.
A number of reports on potential toxicity of nanoparticles are available, but there is still a lack of knowledge concerning bioaccumulation. The aim of this work was to investigate how different ...sources of zinc, such as uncoated and unmodified ZnO nanoparticles, ZnCl
2 in solution, and macropowder ZnO influence the bioaccumulation of this metal in the terrestrial isopod
Porcellio scaber. After exposure to different sources of Zn in the diet, the amount of assimilated Zn in whole body, the efficiency of zinc assimilation, and bioaccumulation factors (BAFs) were assessed. The bioaccumulation potential of Zn was found to be the same regardless of Zn source. The amount of assimilated Zn and BAF were dose-dependent, and Zn assimilation efficiency was independent of exposure concentrations. The Zn assimilation capacity was found to be up to 16% of ingested Zn. It is known that as much as approximately 20% of Zn can be accreted from ZnO particles by dissolution. We conclude that bioaccumulation of Zn in isopods exposed to particulate ZnO depends most probably on Zn dissolution from ZnO particles and not on bioaccumulation of particulate ZnO.
We studied the compartmentalization of cadmium and zinc in the oligochaete
Tubifex tubifex. The subcellular distribution was followed over time and levels of metallothionein-like proteins were ...measured. The impact of the speciation on the trophic transfer was studied by calculating the assimilation efficiencies of metals from Tubificidae fed to carp. It was found that carp were able to assimilate 9.8% of the cadmium. The expected assimilated amount of cadmium, based on the subcellular fractions which are thought to be trophically available, is however 72%. The zinc assimilation results suggest that the debris fraction is at least partially available to predators. Differential centrifugation techniques provide information about the tissue compartmentalization in aquatic organisms but it is not straightforward to directly link internal speciation in prey items to the actual assimilation in the predator. The possible impact that the compartmentalization of cadmium in
T. tubifex will have on the toxicity to the organism is also discussed.
The internal metal speciation in prey items is not clearly linked to the actual assimilation in predators.
This study investigated whether the nature of the binding of the trace metals cadmium, silver and zinc accumulated by phytoplankton can affect their subsequent assimilation efficiencies (AE) in 3 ...filter-feeding benthic invertebrates, the green musselPerna viridis, the clamRuditapes philippinarumand the barnacleBalanus amphitrite. Seven phytoplankton species were chosen from a wide systematic range to ensure large differences in the partitioning of their accumulated trace metals into 3 fractions: (1) exchangeable metal adsorbed on the outside of the cells, as defined by extraction with the chelating agent 8-hydroxyquinoline-5-sulphonate; (2) incorporated metal that is in a soluble form; and (3) insoluble incorporated metal. There were few significant correlations between AE and the percentage of phytoplankton metal incorporated into any 1 fraction or combination of fractions. There is no support, therefore, for a generalised conclusion that any of the 3 fractions isolated represents the sole form of phytoplankton metal that is bioavailable for trophic transfer to a herbivore. Even trace metals bound to the insoluble fraction in phytoplankton may be bioavailable to herbivores. Furthermore, there were no consistent effects of phytoplankton concentration on metal AEs in 1 of the herbivores—P. viridis. There was no evidence that the AE of any of the 3 trace metals was changed when the herbivores were feeding on the phytoplankton species (Thalassiosira weissflogii) on which they were fed during acclimation.
Microbes have developed high-affinity uptake mechanisms to assimilate iron (Fe) and other metals such as aluminum (Al), gallium (Ga), chromium (Cr), and copper (Cu). Siderophores, which are metal ...chelating compounds, and membrane receptor proteins are involved in these specialized mechanisms. A few siderophore-producing microorganisms associated with plant roots also influence the uptake of some metals. In this study, the potential microbial-assisted Cu and Fe uptake by Phaseolus vulgaris (common bean) plants was evaluated. Seedlings of cultivated common bean varieties Bayo-INIFAP (B) and Negro-150 (N) and wild types yellowish (WY) and black (WB) were developed in the presence of a Cu and Fe solution and associated with the siderophore-producing microorganisms R. leguminosarum bv. Phaseoli (strains 19, 44, and 46); Pseudomonas fluorescens (strain Avm), and Azospirillum brasilense (strain 154). Seedlings of cultivated variety N and black wild type WB inoculated with the strain CPMex.44 accumulated 71% and 30% more Fe than the un-inoculated plants, respectively; however, the wild black bean accumulated the highest absolute amount of Fe (221.56 mg/kg of dry matter) as compared with the cultivated black variety N (126.16 mg/kg of dry matter) (P < 0.05). In the wild type WY seedlings, the highest Fe accumulation was observed when the seeds were inoculated with the Pseudomonas strain Avm (206 mg/kg of dry matter) (P < 0.05). The interaction of Pseudomonas strain Avm with seedlings of the cultivated B variety and the wild type WB promoted the highest accumulation of Cu (51 and 54 mg/kg of dry matter, respectively), 7 and 14 mg more than in the respective non-inoculated seedlings. No promotion of Fe accumulation was observed in the seedlings of the cultivated B variety and in roots; instead, less Fe was accumulated. The wild type WY did not show any improvement in Cu accumulation. In this study, Rhizobium strains promoted Fe but not Cu uptake in P. vulgaris seedlings while Pseudomonas strains promoted the uptake of both Cu and Fe.
The relationships between plant and soil systems were investigated using multivariate statistical methods and relative ionic impulsions. Soil samples were taken from three locations and wild plant ...species consisted of: Poa, Pteridium aquilinum, Diplotaxis, Plantago lanceolata and Trifolium repens. The content of Mg, Ca, Na, K, Mn, Fe, Pb, Co, Ni, Cu, Zn and Cr in soils and plants was determined. A five-step chemical fractionation procedure (speciation) was applied to soil samples. Total metal contents were determined and amounts extracted with HCl, EDTA and DTPA were measured. Pb, Co, Ni, Cu, Fe, Zn, Cd and Cr in soils (considered as microconstituents for plants) show a greater number of statistically significant relationships with plant contents than those shown by macroconstituents (Mg, Ca, Na, K and Mn). On the other hand, only Zn and Pb extracted with EDTA and DTPA seem to be related to metal contents in wild plants. When using relative ionic impulsions, any soil fraction (obtained from the fractionation procedure, including the soluble fraction, which is the sum of all the fractions except the residual) is suitable for the study of soil-plant system, suggesting a global balance among all the fractions. Our results suggested an active assimilation for K and a passive uptake for Na, Ca and Mn. Furthermore, Fe seemed to favour the active assimilation of the other microelements.
This chapter explores the metal chemistry of different types of marine hydrothermal environments, the metal requirements of hyperthermophiles, the nature and constraints of their interactions with ...metals, and the biogeochemical implications of hyperthermophile‐metal interactions. Metalloenzymes form a major part of metalloproteomes and reflect the bioavailability of metals within a given environment that are (or were at some point during their evolution) the most accessible. Dissimilatory iron reduction has been studied extensively in just four groups of hyperthermophilic archaea and one hyperthermophilic bacterium. The reduction potential and pH of an environment also appear to affect the growth rates of hyperthermophiles on iron. It is clear that there is extensive interaction between metals and hyperthermophilic microbes from hydrothermal environments, and yet the study of the nature of these interactions is in its infancy. Dissimilatory metal reduction may be limited by the organism's ability to transfer electrons from its cytoplasm to the typically insoluble metal acceptor. Therefore, it is necessary to determine the respiratory mechanisms and how they lead to energy conservation, especially because the physiological mechanisms for metal reduction in hyperthermophiles differ from those found in mesophilic bacteria based on the lack of polyheme c‐type cytochromes, a periplasm, and an outer cell wall membrane. Further study of hyperthermophilemetal interactions in hydrothermal environments will create a new understanding of the basic principles that govern a broad array of metabolic processes and a significant portion of the Earth's biosphere.
The general trends in the purity changes of the environment in connection with the urbanistic technogenesis were analyzed on the example of the largest city of Western Ukraine – Lviv – and its ...outskirts, Dublyany. The characteristic changes of some parameters of the main environmental factors – transformed ecosystems, including biogeochemical properties of edaphotope and pollution by heavy metals are described. Urbanization leads to a tendency of parkerising, alkalinization and significant measure of green zone soil contamination with heavy metals. The increase of the complex pressure of urban anthropogenic environment on vegetation is revealed and current changes of the chemical composition of dry matter of leaves of trees in terms of heavy metal content and structure-energy metabolites are analyzed. A significant accumulation of some chemical elements in the assimilation system of Quercus robur L. and Cercidiphyllum japonicum Siebold et Zucc. was found, their species-specific features of ash accumulative ability were revealed. Cercidiphyllum japonicum is proved to be a promising and effective, in terms of cleaning the environment from man-made pollution, decorative plant in the green belt of cities in the regions of Roztochchia and Pasmove Pobuzhya. Under the influence of edaphotope transformation and pollution in the assimilation bodies of woody plants some structural and metabolic changes occur to adapt to the new to their species environment. Oak as autochthonous species, has signs of stability of the metabolic system of assimilation to the urban genic changes. Cercidiphyllum’s structure demonstrates plasticity of dry matter of leaves, designed to adapt to the new environment acclimatization of exotic species, and thus performs an effective metal storage function in a green area of the city.
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