Biological methods are a promising approach to treating wastewater in order to produce water of an appropriate quality for sub-potable water purposes, thus reducing pressure on potable water sources. ...Daphnia magna are organisms that filter on small suspended particles and bacteria and so may be able to clarify and disinfect wastewater. However, Daphnia magna are sensitive to common chemicals and might be vulnerable to the quality of the wastewater. This study analyses the filtration, mobility and mortality rates of Daphnia magna exposed to seven days of changing concentrations of ammonium, nitrite, nitrate and phosphate. Inactivation increased with the time of exposure for both nitrite and ammonium, with a 50% inactivation in Daphnia magna filtrations after 7 days of exposure at nitrite concentrations above 6 ppm and ammonium concentrations above 40 ppm. The Daphnia filtration remained unaltered in the nitrate and phosphate concentrations. Mortality increased with nitrite and ammonium concentrations, but not with phosphate or nitrate. The swimming velocity of Daphnia magna individuals decreased when both nitrite and ammonium concentrations increased and also with phosphate concentrations above 30 ppm. However, Daphnia magna swimming velocities remained unaltered in the presence of nitrate concentrations below 100 ppm.
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•Nitrite concentration above 6 ppm produces inactivation in the Daphnia magna filtration.•Ammonium concentration above 40 ppm produces inactivation in the D. magna filtration.•D. magna inactivation increased with the exposure time to the chemical concentration.•D. magna swimming velocity, mortality and filtration were used as bioindicators.•D. magna filtration was not altered when exposed to nitrate or phosphate.
The environmental contamination by microplastics is a global challenge to ecosystem and human health, and the knowledge on the long-term effects of such particles is limited. Thus, the effects of ...microplastics and post-exposure recovery were investigated over 4 generations (F0, F1, F2, F3) using Daphnia magna as model. Effect criteria were parental mortality, growth, several reproductive parameters, and population growth rate. Microplastics exposure (0.1mg/l of pristine polymer microspheres 1–5μm diameter) caused parental mortality (10–100%), and significantly (p≤0.05) decreased growth, reproduction, and population growth rate leading to the extinction of the microplastics-exposed model population in the F1 generation. Females descending from those exposed to microplastics in F0 and exposed to clean medium presented some recovery but up to the F3 generation they still had significantly (p≤0.05) reduced growth, reproduction, and population growth rate. Overall, these results indicate that D. magna recovery from chronic exposure to microplastics may take several generations, and that the continuous exposure over generations to microplastics may cause population extinction. These findings have implications to aquatic ecosystem functioning and services, and raise concern on the long-term animal and human exposure to microplastics through diverse routes.
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•Transgerational effects and recovery from microplastics exposure were investigated in D. magna•Microplastics (0.1mg/l) decreased growth, reproduction and population growth rate•Microplastics caused the extinction of microplastics-exposed population in 2 generations•The recovery model population did not recover completely up to the F3 generation
The rapid increase in plastic use over the last few decades has resulted in plastic pollution in freshwater and marine ecosystems. However, more attention has been paid to plastic pollution in marine ...ecosystems than to freshwater ecosystems. This research determined microplastic ingestion by Daphnia magna and the potential effect of microplastics on the organism's survival and reproduction. The study also examined the potential of microplastics to enhance algal growth in support of understanding effects of microplastic ingestion on the organism. When exposed to 25, 50, and 100mg/L fluorescent green polyethylene microbeads at size of 63–75μm, D. magna ingested significant amount of plastic microbeads. The number of ingested beads increased with increasing particle concentration and exposure time. However, no significant effect on survival and reproduction was observed although the gut of D. magna was filled with plastic microbeads. In the algal experiment, Raphidocelis subcapitata grew more in the exposure media with the present of plastic microbeads than without plastic microbeads. This result suggests that plastic microbeads could serve as substrates for R. subcapitata to grow. Raphidocelis subcapitata then could be transferred to the organism's gut and provided energy for survival and reproduction. Results of the present study add to the literature of microplastic ingestion by aquatic organisms. Caution should be taken when interpreting hazards of microplastics based on ingestion, such as the measurement unit and the presence of algae in the environment.
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•Daphnia magna ingested plastic microbeads at size of 63–75μm.•Body concentrations of microplastics increased with exposure time.•No significant effect on survival and reproduction of D. magna was found.•Microplastics enhanced algae growth.•A procedure for quantifying microplastics in D. magna's gut was presented.
Microplastic (μPs) contamination represents a dramatic environmental problem threatening both aquatic and terrestrial organisms. Although several studies have highlighted the presence of μPs in ...aquatic environments, the information regarding their toxicity towards organisms is still scant. Moreover, most of the ecotoxicological studies of μPs have focused on marine organisms, largely neglecting the effects on freshwater species. The present study aimed at exploring the effects caused by 21-days exposure to three concentrations (0.125, 1.25 and 12.5 μg/mL) of two differently sized polystyrene microplastics (PμPs; 1 and 10 μm) to the Cladoceran Daphnia magna. The ingestion/egestion capability of daphnids (<24 h) and adults, the changes in individual growth and behavior, in terms of changes in swimming activity, phototactic behavior and reproduction, were investigated. Both particles filled the digestive tract of daphnids and adults within 24 h of exposure at all the tested concentrations. Ingested PμPs remained in the digestive tract even after 96 h in a clean medium. For both particles, an overall increase in body size of adults was noted at the end of the exposure to the highest tested concentrations, accompanied by a significant increase in swimming activity, in terms of distance moved and swimming velocity, and by an alteration of the phototactic behavior. A significant increase in the mean number of offspring after the exposure to the highest PμPs concentrations of different size was recorded. Polystyrene μPs can affect behavioral traits of D. magna leading to potentially harmful consequences on population dynamics of this zooplanktonic species.
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•Behavioural effects caused by polystyrene microplastics on D. magna were studied.•Microparticles were observed into the digestive tract of daphnids and adults.•Unexpected increase in body size of adults and swimming activity was noted.•An increase in reproductive effort at high microparticle concentration was noted.
Herein we systematically examined the roles of water chemistry (pH, dissolved organic carbon (DOC), and divalent cations) and particle surface functionality that control the aqueous stability, ...aggregation, and toxicity of engineered nanoplastic particles in simulated natural environmental conditions. Model polystyrene latex nanoparticles (PLNPs) with three different functional groups, namely unmodified (uPLNPs), amine-modified (aPLNPs), and carboxyl-modified (cPLNPs), were investigated. Results indicate that the presence of only DOC increased the surface charge and exhibited negligible effects on the size distribution of the PLNPs in aqueous suspensions. The presence of the divalent cations (Ca2+ and Mg2+) was observed to decrease the surface charge and increase the size of the PLNPs. The coexistence of DOC and the divalent cations enhanced the extent of aggregation of the PLNPs in the water columns. The surface modification and pH were sensitive factors influencing the stability of PLNPs during long-term suspension when DOC and the divalent cations coexisted. Direct visual further testified the conclusions on the combined effects of solution and surface chemistry parameters. Furthermore, in situ transmission electron microscope observations revealed that the enhancement of PLNP aggregation in the presence of DOC and the divalent cation was caused by bridge formation. Toxicity test indicated the PLNPs exhibited acute toxicity and physical damage to Daphnia magna. The more complex the solution conditions, the more toxicity the aPLNPs and cPLNPs. Analysis of mode of toxic action implied that the PLNPs mainly caused the accumulation of oxidative damage to the gut of D. magna.
•Coexistence of DOC and divalent cations enhanced aggregation extent of PLNPs.•Enhancement of PLNP aggregation was attributed to bridge formation.•PLNPs exhibited acute toxicity and physical damage to D. magna.•PLNPs mainly caused the accumulation of oxidative damage to the gut of D. magna.•Behavior and toxicity of PLNPs was associated with water and surface chemistry.
Recent studies revealed that freshwaters are not only polluted by chemicals, but also by persistent synthetic material like microplastics (plastic particles <1 mm). Microplastics include a diverse ...range of characteristics, e.g. polymer type, size or shape, but also their tendency to sorb pollutants or release additives. Although there is rising concern about the pollution of freshwaters by microplastics, knowledge about their potential effects on organisms is limited. For a better understanding of their risks, it is crucial to unravel which characteristics influence their effects on organisms. Analysing effects by the mere particles is the first step before including more complex interactions e.g. with associated chemicals. The aim of this study was to analyse potential physical effects of microplastics on one representative organism for limnic zooplankton (Daphnia magna). We investigated whether microplastics can be ingested and whether their presence causes adverse effects after short-term exposure. Daphnids were exposed for up to 96 h to 1-μm and 100-μm polyethylene particles at concentrations between 12.5 and 400 mg L−1. Ingestion of 1-μm particles led to immobilisation increasing with dose and time with an EC50 of 57.43 mg L−1 after 96 h. 100-μm particles that could not be ingested by the daphnids had no observable effects. These results underline that, considering high concentrations, microplastic particles can already induce adverse effects in limnic zooplankton. Although it needs to be clarified if these concentrations can be found in the environment these results are a basis for future impact analysis, especially in combination with associated chemicals.
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•We analysed acute effects of raw 1-μm and 100-μm PE-particles on Daphnia magna.•1-μm particles are distributed in the water column, 100-μm particles are floating.•1-μm particles are ingested by D. magna and cause immobilisation.•Immobilisation of daphnids increases with dose of 1-μm particles and time.•EC50 of 1-μm particles in D. magna was 57.43 mg L−1 after 96 h.
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•Singular and combined toxicity of C60 with various solvents was tested on Daphnia.•Linseed, olive, and sunflower oil were less toxic than 1,2,4-trimethylbenzene.•Sunflower oil had ...the lowest singular toxic impacts on Daphnids.•Adding C60 in low concentration to olive and sunflower oil reduced their toxicity.•C60 in olive oil had the lowest toxic impacts on Daphnids.
Linseed oil, olive oil, and sunflower oil were selected based on green chemistry principles and C60 solubility as alternative solvents to replace 1,2,4-trimethylbenzene (TMB) for C60 manufacturing. Singular acute toxicity experiments of C60 and the four solvents was performed using Daphnia magna to identify the solvent with the lowest toxicity and estimate the toxicity of C60. The EC50 for C60 was estimated to be higher than 176 ppm. The toxicity of the solvents increased from sunflower oil to olive oil, linseed oil, and TMB. Combined toxicity tests were conducted to investigate the interaction between C60 and the solvent since essential oils can be nanocarriers and facilitate the transport of C60 into the cell membranes, which would increase its toxicity. Various concentrations of C60 (0, 11, 22, 44, 88, and 176 mg/L) were mixed with solvents at their EC50 concentrations. The toxicity of linseed oil increased with increasing C60 concentrations. For olive and sunflower oil, the toxicity was lowered with low concentrations of C60. Olive oil was determined to be a suitable solvent for C60 manufacturing based on singular and combined toxicity assessments. This study showed the importance of considering combined toxicity for solvent selection.
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