Representative Aquatic Organisms Research Articles

Use of large datasets of measured environmental concentrations for the ecological risk assessment of chemical mixtures in Italian streams: A case study

A method to evaluate the ecological risk of chemical mixtures in water bodies is here presented. In the first phase, the approach considered routine chemical monitoring data (MEC: measured environmental concentrations) obtained from the Italian National Institute for Environmental Protection and Research, which were georeferenced to a single coordinate system for each monitoring station. The overall mixture toxicity were then evaluated for three representative aquatic organisms (algae, Daphnia, fish) using the concentration addition model to combine exposure with ecotoxicological data (from different databases). A database management system was used to facilitate the creation, organisation, and management of the large datasets of this study. The outputs were obtained as GIS-based mixture risk maps and tables (listing the toxic unit of mixtures and individual substances) useful for further analysis. The method was applied to an Italian watershed (Adda River) as a case study. In the first phase, the mixture toxicity was calculated using two scenarios: best- and worst-case; wherein the former included only those compounds that were be detected, while the latter involved also substances with concentrations below the limit of quantification. The ratio between the two scenarios indicated the range within which mixture toxicity should ideally vary. The method demonstrates that these ratios were very small when the calculated toxicity using the best case indicated a potential risk and vice versa, indicating that the worst-case scenario could not be appropriate (extremely conservative). Consequently, in the successive phase, we focused exclusively on the best-case scenario. Finally, this approach allowed the priority mixture identification (those most likely occurring in the analysed water samples), algae as the organism at the highest risk, and the substances that contributed the most to the overall mixture toxicity (terbuthylazine and s-metolachlor for algae, and chlorpyrifos and chlorpyrifos-CH3 for Daphnia and fish).

The Crucial Role of Environmental Coronas in Determining the Biological Effects of Engineered Nanomaterials.

In aquatic environments, a large number of ecological macromolecules (e.g., natural organic matter (NOM), extracellular polymeric substances (EPS), and proteins) can adsorb onto the surface of engineered nanomaterials (ENMs) to form a unique environmental corona. The presence of environmental corona as an eco-nano interface can significantly alter the bioavailability, biocompatibility, and toxicity of pristine ENMs to aquatic organisms. However, as an emerging field, research on the impact of the environmental corona on the fate and behavior of ENMs in aquatic environments is still in its infancy. To promote a deeper understanding of its importance in driving or moderating ENM toxicity, this study systemically recapitulates the literature of representative types of macromolecules that are adsorbed onto ENMs; these constitute the environmental corona, including NOM, EPS, proteins, and surfactants. Next, the ecotoxicological effects of environmental corona-coated ENMs on representative aquatic organisms at different trophic levels are discussed in comparison to pristine ENMs, based on the reported studies. According to this analysis, molecular mechanisms triggered by pristine and environmental corona-coated ENMs are compared, including membrane adhesion, membrane damage, cellular internalization, oxidative stress, immunotoxicity, genotoxicity, and reproductive toxicity. Finally, current knowledge gaps and challenges in this field are discussed from the ecotoxicology perspective.

Acute toxicity of fluazinam to aquatic organisms and its bioaccumulation in Brachydanio rerio.

Fluazinam (FZN) is a dinitroaniline fungicide. To evaluate the environmental risk of FZN in aquatic environments and ascertain the potential danger to typical aquatic organisms in China, the acute toxicity of FZN to representative aquatic organisms, including Brachydanio rerio, Chlorella vulgaris Beij., Daphnia magna Straus, and Xenopus laevis, was measured, and its bioaccumulation properties in Brachydanio rerio were further investigated. The results showed that the acute toxicity of FZN to Brachydanio rerio and Xenopus laevis is extremely high, and the bioaccumulation factor BCF8d of FZN in Brachydanio rerio ranges between 2287 and 3570, implying that it has high bioaccumulation properties. FZN poses a strong environmental risk for aquatic organisms and possesses great bioaccumulation properties, which may cause pollution to aquatic environments.

Perfluoroalkyl substances in the Yangtze River: Changing exposure and its implications after operation of the Three Gorges Dam

Potential ecological risk from perfluoroalkyl substances (PFASs) under changing exposure in large river systems has become a new challenge recently. Based on systematic monitoring of PFASs at 43 hydrologic stations along a 4300 km continuum of the Yangtze River, we investigated the ecological risk of PFASs under changing exposure resulting from operation of the Three Gorges Dam (TGD). Importantly, perfluorooctanoic acid (PFOA) was found extensively exposed in most mainstream water samples, accounting for about 90% of the total content of PFASs in both spring and autumn, while short-chain PFASs contributed more than PFOA in sediment. The significant inversion of long-chain PFASs occurrence from sediment to water reflected a profound change in exposure due to loss of finer sediments resulting from long-distance and long-term scour of the riverbed downstream of the TGD. The coarsening of bed materials would weaken sorption of long-chain PFASs in sediments and enhance their exposure in water, resulting in substantial increase of ecological risk to representative aquatic organisms. In the long term, particular attention should be paid to reduction of PFOA discharge to downstream of the TGD from typical industries. This also highlights the significance of huge dams to alternative exposures of persistent organic pollutants and the necessity of new strategy for ecological risk management of large river systems.

The acute toxicity of bisphenol A and lignin-derived bisphenol in algae, daphnids, and Japanese medaka.

Risk assessing newly synthesized chemicals prior to their applications is extremely important, if we want to ensure substitution of risky chemicals with more benign ones. During the past two decades, many analogs of bisphenol A (BPA) have been manufactured, while their toxicity remains less studied. The aim of this study was to compare the acute toxicity of a synthesized lignin-derived BPA (LD-BP) with that of BPA in representative aquatic organisms including two algal species (Chlorella pyrenoidosa and Scenedesmus obliquus), a cladoceran species (Daphnia magna), and the Japanese medaka (Oryzias latipes). The results revealed that the two algal species showed different responses to the two chemicals. For C. pyrenoidosa, both BPA and LD-BP stimulated growth within 48h of exposure, except for the 50mgL-1 of LD-BP treatment. After 96 and 144h of exposures, BPA stimulated the growth of C. pyrenoidosa at low-exposure concentrations but inhibited its growth at high concentrations, while LD-BP caused a concentration-dependent response in C. pyrenoidosa. S. obliquus exhibited a monotonic concentration-response curve for both BPA and LD-BP exposures. For both D. magna and O. latipes, concentration-responses were monotonic with 96h-LC50 of BPA and LD-BP of 11.7 and 5.0mgL-1 and 9.4 and 4.1mgL-1, respectively. Our results demonstrate that LD-BP is more toxic than BPA in the representative aquatic organisms, and it can pose higher ecological risk to the aquatic ecosystem than BPA.

Potential risk of biochar-amended soil to aquatic systems: an evaluation based on aquatic bioassays.

It is vital to address potential risks to aquatic ecosystems exposed to runoff and leachates from biochar-amended soils, before large scale applications can be considered. So far, there are no established approaches for such an assessment. This study used a battery of bioassays and representative aquatic organisms for assessing the acute toxicity of water-extractable fractions of biochar-amended soil, at reported application rates (80 t ha(-1)). Biochar-amended aqueous soil extracts contained cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), manganese (Mn), zinc (Zn), nickel (Ni), lead (Pb), arsenic (As) and mercury (Hg) (Σmetals 96.3 µg l(-1)) as well as the 16 priority PAHs defined by the U.S. Environmental Protection Agency (Σ16PAHs 106 ng l(-1)) at contents in the range of current EU regulations for surface waters. Nevertheless, acute exposure to soil-biochar (SB) extracts resulted in species-specific effects and dose-response patterns. While the bioluminescent marine bacterium Vibrio fischeri was the most sensitive organism to aqueous SB extracts, there were no effects on the growth of the microalgae Pseudokirchneriella subcapitata. In contrast, up to 20 and 25% mobility impairment was obtained for the invertebrate Daphnia magna upon exposure to 50 and 100% SB extract concentrations (respectively). Results suggest that a battery of rapid and cost-effective aquatic bioassays that account for ecological representation can complement analytical characterization of biochar-amended soils and risk assessment approaches for surface and groundwater protection.

Environmental risk assessment for quaternary ammonium compounds: a case study from Austria

Quaternary ammonium compounds (QAC) are widely used as disinfectants, biocides, and detergents, among a variety of other applications. The cationic surface-activity of QAC determines their potential to act as a biocide on both target and non-target organisms. This study aims to provide a broad-based environmental risk characterization and evaluation for selected QAC with particular focus on the situation in Austrian rivers. A modular study design was employed involving environmental exposure characterization, QAC fate and effect analysis in wastewater, ecotoxicological effect characterization, and environmental risk evaluation. A wide array of Austrian surface waters and wastewater effluents were screened for the selected key compounds, benzalkonium chlorides and dialkyldimethylammonium chlorides with different C-chain lengths. Ecotoxicological effect characterization was based on both microbiotests for a set of representative aquatic organisms and a literature review. For risk evaluation, the PEC/PNEC ratio was above 1 for some rivers. Notably, small rivers with a high particulate matter were contaminated with QAC in the case of high water incidents. Hence, for the Austrian sites studied, a QAC-derived risk to sensitive aquatic non-target organisms could not be excluded.

Distribution of Contaminants in Aquatic Organisms from East Fork Poplar Creek

The ecological risk assessment of East Fork Poplar Creek (EFPC) in Oak Ridge, Tennessee, investigated the nature and magnitude of the observed or expected adverse effects of the site's organic and inorganic contaminants on the ecosystem structure and function. Aquatic biota such as benthic macroinvertebrates, crayfish (Astacidae), redbreast sunfish (Lepomis auritus), and stonerollers (Campostoma anomalum), representative of various habitats, were sampled for whole-body contaminant analysis. The whole-body residue analysis of the representative aquatic organisms revealed the presence of over 50 contaminants in varying proportions. The relative whole-body distribution of organic contaminants such as mixtures of polychlorinated biphenyls, polycyclic aromatic hydrocarbons, and pesticides was comparable among the indicator organisms. The relative whole-body distribution of inorganic contaminants was, however, less consistent. Physicochemical variables characteristic of organic contaminants—such as long octanol/water partition coefficient (logKow), log aqueous solubility, and log bioconcentration factors (log BCF), and chemical uptake efficiency (E) unique for the organisms sampled for chemical analysis—were used to explain the observed whole-body distribution of contaminants in the aquatic organisms from EFPC.

Use of FSCBG to Predict Pesticide Deposition on a Piedmont Pine Seed Orchard

Abstract This study demonstrates the usefulness of the FSCBG aerial simulation model as a forest management tool. In general, the model closely predicted the measured deposition of bifenthrin in a pine seed orchard. An exception was the August application during which wind gusts caused the pesticide to drift further from the application area than predicted by the model. FSCBG tended to underpredict drift and evaporative losses based on the input parameters of this study. Simulations of other registered pine seed orchard pesticides demonstrated no potential environmental risk to representative aquatic organisms in surrounding ponds or waterways based on the test conditions presented. South. J. Appl. For. 19(4):145-150.

A summary of the acute toxicity of 14 phthalate esters to representative aquatic organisms

AbstractAcute aquatic toxicity studies were performed with 14 commercial phthalate esters and representative freshwater and marine species. The 14 esters were dimethyl phthalate; diethyl phthalate; di‐n‐butyl phthalate; butyl benzyl phthalate; dihexyl phthalate; butyl 2‐ethylhexyl phthalate; di‐(n‐hexyl, n‐octyl, n‐decyl) phthalate; di‐(2‐ethylhexyl) phthalate; diisooctyl phthalate; diisononyl phthalate; di‐(heptyl, nonyl, undecyl) phthalate; diisodecyl phthalate; diundecyl phthalate; and ditridecyl phthalate. Phthalate esters with alkyl chain lengths of four carbon atoms or fewer were determined to be acutely toxic at concentrations ranging from 0.21 to 377 mg/L depending on the ester and the solubility of the test chemical in water. There was a general trend for the lower‐molecular‐weight phthalate esters (C1 to C4 alkyl chain lengths: dimethyl phthalate; diethyl phthalate; di‐n‐butyl phthalate; and butyl benzyl phthalate) to become more toxic with decreasing water solubility for all species tested. There were only minor differences in species sensitivity to each of the phthalate esters. Phthalate esters with alkyl chain lengths of six carbon atoms or more were not acutely toxic at concentrations approaching their respective aqueous solubilities. Insufficient mortality occurred to calculate either LC50 or EC50 values or acute no‐observed‐effect concentrations for these higher‐molecular‐weight phthalate esters. The lack of toxicity observed for the higher‐molecular‐weight phthalate esters resulted from their limited water solubility (≤1.1 mg/L).