Nanosized titanium dioxide (nTiO2) is widely used in products, warranting its discharge from various sources into surface water bodies. However, nTiO2 co-occurs in surface waters with other ...contaminants, such as metals. Studies with nTiO2 and metals have indicated that the presence of natural organic matter (NOM) can mitigate their toxicity to aquatic organisms. In addition, “aging” of nTiO2 can affect toxicity. However, it is a research challenge, particularly when addressing sublethal responses from dietary exposure over multiple generations. We, therefore exposed the alga Desmodesmus subspicatus to nTiO2 (at concentrations of 0.0, 0.6 and 3.0 mg nTiO2/L) in nutrient medium aged for 0 or 3 days with copper (Cu) at concentrations of 0 and 116 µg Cu/L and with NOM at concentrations equivalent to 0 and 8 mg total organic carbon (TOC) per litre. Subsequently, the exposed alga was fed to Daphnia magna for 23 days over two generations and survival, reproduction and body length were assessed as endpoints of toxicity. In parallel, Cu accumulation and depuration from D. magna were measured. The results indicate that the reproduction of D. magna was the most sensitive parameter in this study, being reduced by 30% (at both parental (F0) and filial (F1) generations) and 50% (at F0 but not F1) due to the dietary Cu exposure in combination with nTiO2 for 0 and 3 days aging, respectively. There was no relationship between the effects observed on reproduction and Cu body burden in D. magna. Moreover, D. magna from the F1 generation showed an adaptive response to Cu in the treatment with 3.0 mg nTiO2/L aged for 3 days, potentially due to epigenetic inheritance. Unexpectedly, the presence of NOM hardly changed the observed effects, pointing towards the function of algal exopolymeric substances or intracellular organic matter, rendering the NOM irrelevant. Ultimately, the results indicate that the transferability of the impacts observed during the F0 to the responses in the F1 generation is challenging due to opposite effect directions. Additional mechanistic studies are needed to unravel this inconsistency in the responses between generations and to support the development of reliable effect models.
•nTiO2 aging controls dietary Cu effects on D. magna over two generations.•Impairments in reproduction were not explained by Cu body burden.•NOM did not substantially affect response variables.•Effect assessment over more than two generations is recommended.
During its aquatic life cycle, nanosized titanium dioxide (nTiO
2
) may interact with natural organic matter (NOM) ultimately altering the ecotoxicity of co-occurring chemical stressors such as heavy ...metals (e.g. copper (Cu)). In this context, the following hypotheses were tested: (1) aging of nTiO
2
along with Cu reduces Cu toxicity, (2) nTiO
2
agglomerates have a lower potential to reduce Cu toxicity and (3) aging of nTiO
2
in presence of NOM reduces Cu toxicity further. A multifactorial test design crossing three nTiO
2
levels (0.0, 0.6 and 3.0 mg/L) with two levels of NOM (0 versus 8 mg total organic carbon (TOC)/L) and seven nominal Cu concentrations (ranging from 0 to 1536 μg/L) aged in ASTM medium for 0, 1, 3 and 6 days was realised, while two aging scenarios were applied (type 1: nTiO
2
jointly aged with Cu; type 2: Cu added after nTiO
2
aging). Subsequently, Cu toxicity was assessed using the immobility of
Daphnia magna
after 48 h of exposure as response variable. The experiments revealed that neither aging duration nor the extent of agglomeration (type 1 vs. type 2 aging) has a substantial impact on Cu induced toxicity. Moreover, it was confirmed that the presence of NOM substantially reduced Cu induced toxicity, independent of the aging scenario and duration. More importantly, the data suggest the ingestion of Cu loaded nTiO
2
as additional exposure pathway contributing to Cu toxicity. In conclusion, it seems unlikely that nTiO
2
concentrations currently detected in or predicted for aquatic ecosystems, which are at least one order of magnitude below the concentration tested here, influence Cu toxicity meaningfully.
•Estimating runoff of veterinary pharmaceuticals after manure application using the FOCUS model.•Comparison of predicted and measured runoff concentrations.•Substantially deviations between predicted ...and measured concentrations.•35% of all concentrations measured in run-off water were underestimated.
Veterinary pharmaceuticals (VPs) are routinely used in livestock breeding. As a consequence, high concentrations of such VPs can be found in liquid manure, which is often applied to arable crops and grassland. From the soil, the VPs may enter surface water bodies via edge-of-field runoff, representing a potential risk to aquatic ecosystems. In the present study, the worst-case runoff predictions obtained by the FOCUS step 3 modeling approach, which is recommended for environmental-risk assessment of VPs in Europe, were compared with fate data obtained from experimental plot studies involving both arable and grassland plots. Five VPs were selected comprising three sulfonamides (sulfadiazine, sulfadimidine, sulfamethoxazole) and two benzimidazoles (flubendazole, fenbendazole). The respective concentrations in runoff were initially estimated using literature data for model parameterization. Subsequently, the scenarios were parameterized specifically for each experimental plot study performed, enabling a direct comparison of the model performance with the close-to-field relevant situation.
Generally, substantial variations between the predicted and measured concentrations of VPs in the runoff were uncovered. Although the FOCUS prediction suggested higher concentrations than were actually measured in 65% of the cases, the runoff concentrations of VPs were underestimated in the remaining 35%. This frequent underestimation of runoff concentrations was primarily observed for the grassland plots (85% of the underestimated situations), whereas the FOCUS predictions largely overestimated the measured concentrations for the arable plots. More strikingly, when involving a difference between the measured and predicted concentrations of 10% as a validity criterion for the model, only one (out of a total of 17) runoff concentration among the five VPs (i.e., sulfadimidine) assessed in the seven scenarios fell within this tolerance margin. Thus, these results demonstrate the substantial uncertainties related to the use of the FOCUS surface water modeling approach for the prediction of VPs introduced with manure and their environmental risk.
Molecular genetic methods continuously uncover cryptic lineages harboured by various species. However, from an applied perspective, it remains unclear whether and to which extent such a genetic ...diversity affects biological traits (e.g. ecological, behavioural and physiological characteristics) and environmental management. We assessed potential deviations regarding the trait ‘environmental stress tolerance’ using individuals from five field populations of each of two cryptic lineages (called A and B) comprised under the nominal species Gammarus fossarum. We used ammonia as a chemical stressor while assessing the feeding rate on leaf discs as a measure of sublethal response. In this context, we established a restriction fragment length polymorphism assay to allow a rapid identification of the lineages. We observed a biologically meaningful and statistically significant twofold higher overall tolerance of one cryptic lineage, lineage B, over the other. Confounding factors that may have the potential to influence the test results, such as life stage, sex, season of collection, parasitism, physiological status of organisms and upstream land‐use patterns of the river catchments, were either controlled for or displayed only minor deviations between lineages. Synthesis and applications. The trait differences observed in the present study seem to be mainly explained by the considerable genetic differentiation between cryptic lineages of one nominal species. Although traits other than tolerance have been minimally investigated in this context, this study indicates implications in the reliability and quality of environmental monitoring and management if cryptic lineage complexes are ignored.
Nanoparticulate titanium dioxide (nTiO
2
) is frequently applied, raising concerns about potential side effects on the environment. While various studies have assessed structural effects in aquatic ...model ecosystems, its impact on ecosystem functions provided by microbial communities (biofilms) is not well understood. This is all the more the case when considering additional stressors, such as UV irradiation — a factor known to amplify nTiO
2
-induced toxicity. Using pairwise comparisons, we assessed the impact of UV (UV-A = 1.6 W/m
2
; UV-B = 0.7 W/m
2
) at 0, 20 or 2000 μg nTiO
2
/L on two ecosystem functions provided by leaf-associated biofilms: while leaf litter conditioning, important for detritivorous invertebrate nutrition, seems unaffected, microbial leaf decomposition was stimulated (up to 25%) by UV, with effect sizes being higher in the presence of nTiO
2
. Although stoichiometric and microbial analyses did not allow for uncovering the underlying mechanism, it seems plausible that the combination of a shift in biofilm community composition and activity together with photodegradation as well as the formation of reactive oxygen species triggered changes in leaf litter decomposition. The present study implies that the multiple functions a microbial community performs are not equally sensitive. Consequently, relying on one of the many functions realized by the same microbial community may be misleading for environmental management.
•Agriculture and river regulation impact the biodiversity of stream organism groups.•Agriculture affects fungal biomass accrual.•River regulation impacts litter decomposition and algal biomass ...accrual.•Forestry in the catchment has little impact on stream structures and functions.•Inferences about the impacts of disturbances at the ecosystem level is challenging.
Ecosystem functioning and community structure are recognized as key components of ecosystem integrity, but comprehensive, standardized studies of the responses of both structural and functional indicators to different types of anthropogenic pressures remain rare. Consequently, we lack an empirical basis for (i) identifying when monitoring ecosystem structure alone misses important changes in ecosystem functioning, (ii) recommending sets of structural and functional metrics best suited for detecting ecological change driven by different anthropogenic pressures, and (iii) understanding the cumulative effects of multiple, co-occurring stressors on structure and function. We investigated variation in community structure and ecosystem functioning of stream ecosystems along three gradients (10–16 independent stream sites each) of increasing impact arising from agriculture, forestry and river regulation for hydropower, respectively. For each stream, we quantified variation in (i) the abiotic environment, (ii) community composition of four organism groups and (iii) three basal ecosystem processes underpinning carbon and nutrient cycling in streams. We assessed the responsiveness of multiple biodiversity, community structure and ecosystem functioning indicators based on variance explained and effect size metrics. Along a gradient of increasing agricultural impact, diatoms and fish were the most responsive groups overall, but significant variation was detected in at least one aspect of community composition, abundance and/or biodiversity of every organism group . In contrast, most of our functional metrics did not vary significantly along the agricultural gradient, possibly due to contrasting, antagonistic effects of increasing nutrient concentrations and turbidity on ecosystem process rates. The exception was detritivore-mediated litter decomposition which increased up to moderate levels of nutrient. Impacts of river regulation were most marked for diatoms, which were responsive to both increasingly frequent hydropeaking and to increasing seasonal river regulation. Among functional indicators, both litter decomposition and algal biomass accrual declined significantly with increasing hydropeaking. Few structural or functional metrics varied with forest management, with macroinvertebrate diversity increasing along the forestry gradient, as did algal and fungal biomass accrual. Together, these findings highlight the challenges of making inferences about the impacts of anthropogenic disturbances at the ecosystem level based on community data alone, and pinpoint the need to identify optimal sets of functional and structural indicators best suited for detecting ecological changes associated with different human activities.
During their aquatic life cycle, nanoparticles are subject to environmentally driven surface modifications (e.g. agglomeration or coating) associated with aging. Although the ecotoxicological ...potential of nanoparticles might be affected by these processes, only limited information about the potential impact of aging is available. In this context, the present study investigated acute (96 h) and chronic (21 d) implications of systematically aged titanium dioxide nanoparticles (nTiO2; ~90 nm) on the standard test species Daphnia magna by following the respective test guidelines. The nTiO2 were aged for 0, 1, 3 and 6 d in media with varying ionic strengths (Milli-Q water: approx. 0.00 mmol/L and ASTM: 9.25 mmol/L) in the presence or absence of natural organic matter (NOM). Irrespective of the other parameters, aging in Milli-Q did not change the acute toxicity relative to an unaged control. In contrast, 6 d aged nTiO2 in ASTM without NOM caused a fourfold decreased acute toxicity. Relative to the 0 d aged particles, nTiO2 aged for 1 and 3 d in ASTM with NOM, which is the most environmentally-relevant setup used here, significantly increased acute toxicity (by approximately 30%), while a toxicity reduction (60%) was observed for 6 d aged nTiO2. Comparable patterns were observed during the chronic experiments. A likely explanation for this phenomenon is that the aging of nTiO2 increases the particle size at the start of the experiment or the time of the water exchange from <100 nm to approximately 500 nm, which is the optimal size range to be taken up by filter feeding D. magna. If subjected to further agglomeration, larger nTiO2 particles, however, cannot be retained by the daphnids' filter apparatus ultimately reducing their ecotoxicological potential. This non-linear pattern of increasing and decreasing nTiO2 related toxicity over the aging duration, highlights the knowledge gap regarding the underlying mechanisms and processes. This understanding seems, however, fundamental to predict the risks of nanoparticles in the field.
Abstract The extensive use of synthetic polymers in our everyday lives has resulted in significant plastic pollution. Superabsorbent polymers (SAPs) are yet another class of anthropogenic materials ...with uncertain environmental implications. SAPs, like polyacrylates (PAA) or polyacrylamides (PAM), find applications in personal care products, construction, wastewater treatment, agriculture and soil remediation. However, when SAPs enter the soil, weathering may change their intended properties, potentially forming plastic-like solid residues over time. This review aims to evaluate the current scientific understanding of the application and environmental fate of SAPs in soil, focusing on the processes driving their potential transformation into solid residues. We explore analytical techniques for the qualitative and quantitative characterization of SAPs and solid SAP residues. Our research provides first insights into the potential mechanisms and conditions governing SAP aging and transformation, advancing our understanding of the fate of SAPs in soil and their impact on soil properties and functioning. There are specific knowledge gaps regarding the influence of climate change on the application and transformation of SAPs in soil. To facilitate future research, we suggest scrutinizing relevant processes of SAP transformation in the field, critically (re)evaluating SAP application to the soil and establishing robust monitoring methods.
The nanoparticle industry is expected to become a trillion dollar business in the near future. Therefore, the unintentional introduction of nanoparticles into the environment is increasingly likely. ...However, currently applied risk-assessment practices require further adaptation to accommodate the intrinsic nature of engineered nanoparticles. Combining a chronic flow-through exposure system with subsequent acute toxicity tests for the standard test organism Daphnia magna, we found that juvenile offspring of adults that were previously exposed to titanium dioxide nanoparticles exhibit a significantly increased sensitivity to titanium dioxide nanoparticles compared with the offspring of unexposed adults, as displayed by lower 96 h-EC(50) values. This observation is particularly remarkable because adults exhibited no differences among treatments in terms of typically assessed endpoints, such as sensitivity, number of offspring, or energy reserves. Hence, the present study suggests that ecotoxicological research requires further development to include the assessment of the environmental risks of nanoparticles for the next and hence not directly exposed generation, which is currently not included in standard test protocols.
Copper accumulating in stream sediments can be transported to adjacent riparian habitats by flooding. Although being an essential element for plants, copper is toxic at high concentrations and ...restricts, among other things, plant growth. Besides copper, invasive plants, such as
, which are known to be tolerant toward heavy metals, modify riparian habitats. If the tolerance of
is higher compared to native plants, this could accelerate invasion under high heavy metal stress. Therefore, we aimed to compare the effect of copper on two common riparian plants, the invasive
and the native
. We performed a pot experiment with a gradient from 0 to 2430 mg kg
of soil copper. We hypothesized that (i) negative effects on plant growth increase with increasing soil copper concentrations with
being less affected and (ii) accumulating higher amounts of copper in plant tissues compared to
. In support of our first hypothesis, growth (height, leaf number) and biomass (above- and belowground) of
were impacted at the 810 mg kg
treatment, while the growth of
was already impacted at 270 mg kg
. Due to 100% mortality of plants, the 2430 mg kg
treatment was omitted from the analysis. In contrast, chlorophyll content slightly increased with increasing copper treatment for both species. While
accumulated more copper in total, the copper uptake by
increased more strongly after exposure compared to the control. In the 810 mg kg
treatment, copper concentrations in
were up to 2238% higher than in the control but only up to 634% higher in
. Our results indicate that
might be able to more efficiently detoxify internal copper concentrations controlling heavy metal effects compared to the native species. This could give
a competitive advantage particularly in polluted areas, facilitating its invasion success.
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