Toxicity of copper oxide nanoparticle suspensions to aquatic biota

Toxicity effects induced by nanosuspensions of CuO (<50?nm; Sigma-Aldrich) on macrophytic algae cells of Nitellopsis obtusa (96-h median lethal concentration [LC50]), microphytic algae Chlorella (30-min median inhibitory concentration [IC50]), shrimp Thamnocephalus platyurus (24-h LC50), and rotifer Brachionus calyciflorus (24-h LC50) were investigated. No substantial differences between the effects of nonsonicated and sonicated nCuO suspensions were observed. The particle size distribution analysis accomplished by the laser diffraction technique at suspension concentration from 3 to 100?mg/L revealed rapid (within 5?min) reagglomeration of the particles after the sonication. The observed adverse effects on N. obtusa cells may be attributed to nanoparticles per se, but not to ionic Cu, because neither chemical analysis nor biological testing (algae survival in the supernatants of suspensions) confirmed the presence of cupric ions in toxic amounts. Contrary to ionic Cu form, nCuO delayed the initial phase of N. obtusa cell membrane depolarization. Lethality tests with rewash demonstrated that the least used 5-min exposure in 100?mg/L nCuO sonicated suspension induced 70% mortality in charophyte cells after 8?d, whereas the rewash after a short exposure to a noticeably toxic concentration of Cu(2+) prevented cell mortality. The obtained data suggested the possible influence of a thick charophyte cell wall on the dynamics of nanotoxicity effects.     

Toxicity of microencapsulated permethrin to selected nontarget aquatic invertebrates

Microencapsulated permethrin (penncapthrin) was evaluated under laboratory conditions for its toxicity toward several nontarget aquatic invertebrates. Average LC50 estimates for selected lotic invertebrates, based on a one hour dosing regime, were: 2.71 mg/L forSimulium vittatum, 4.59 mg/L forHydropsyche spp., and 13.41 mg/L forIsonychia bicolor. In acute static tests withDaphnia magna, there was no significant difference (p0.05) between the toxicity of penncapthrin at 96 h (LC50 range: 6.80–22.5 g/L) and the EC formulation at 72 h (LC50 range: 0.6–21 g/L). Comparatively, the toxicity of microencapsulated methyl parathion (penncap-m) was not significantly different from that of penncapthrin towardD. magna, the former having LC50 estimates ranging form 0.3–12.25 g/L. LC50 estimates associated withDaphnia pulex ranged from 19 to 131 g/L. The toxicity of penncapthrin and penncap-m towardD. pulex was difficult to determine because of frequent control mortality due to food deprivation resulting from the need to run tests for longer than 48 h. In successful tests, LC50 estimates ranged from 19 to 28 g/L for penncapthrin and 0.08 to 25 g/L for penncap-m after 72 h exposure. In long term toxicity tests, 95% of D. magna at 1 g/L, 44% at 10 g/L, and 20% at 15 g/L survived after 39 days exposure. Less than 15% ofD. pulex survived over the same concentration range following 32 days exposure. Despite some drawbacks, long-term toxicity tests were more appropriate than short-term tests for evaluating microencapsulated sticides because of reduced variability in LC50 estimates and lower control mortality.     

Toxicity of selected priority pollutants to various aquatic organisms

Toxicity tests were conducted with selected compounds listed by the United States Environmental Protection Agency (EPA) as priority pollutants. Acute toxicity information was determined for acenaphthene, arsenic trioxide, cadmium chloride, mercury(II) chloride, silver nitrate, chlordane, endosulfan, and heptachlor. Acute tests were conducted using one or more of the following species: fathead minnows (Pimephales promelas), channel catfish (Ictalurus punctatus), rainbow trout (Salmo gairdneri), brown trout (Salmo trutta), brook trout (Salvelinus fontinalis), bluegills (Lepomis macrochirus), snails (Aplexa hypnorum), or chironomids (Tanytarsus dissimilis). Acute values from these tests ranged from a silver nitrate 96-hr LC50 of 6.7 micrograms/liter for fathead minnows to an arsenic trioxide 48-hr LC50 of 97,000 micrograms/liter for chironomids. In addition to acute tests, a fathead minnow embryo-larval exposure was conducted with silver nitrate to estimate chronic toxicity. The estimated maximum acceptable toxicant concentration for silver nitrate, based on fathead minnow survival, lies between 0.37 and 0.65 micrograms/liter.     

Acute and embryo-larval toxicity of phenolic compounds to aquatic biota

Because of the prevalence of phenolic compounds in various types of effluents, both acute and embryo-larval bioassays were performed on eight phenolic compounds with rainbow trout, fathead minnows andDaphnia pulicaria. In flow-through bioassays, the 96-hr LC₅₀ values for rainbow trout and fathead minnows ranged from <0.1 mg/L for hydroquinone to >100 mg/L for resorcinol.Daphnia pulicaria was consistently the least sensitive species tested as measured in 48-hr bioassays, while fathead minnows and rainbow trout varied in their relative sensitivity to phenolics as measured in 96-hr tests. Fathead minnows were more sensitive to phenol at 25°C than at 14°C.In embryo-larval bioassays with phenol, fathead minnow growth was significantly reduced by 2.5 mg/L phenol, while rainbow trout growth was significantly reduced by 0.20 mg/L phenol. For both species the embryolarval effects concentration was 1.1% of the 96-hr LC₅₀. Another embryolarval bioassay was attempted withp-benzoquinone, a highly toxic phenolic compound found in fossil fuel processing wastewaters, which was discontinued because the compound was rapidly degraded chemically or biologically in the headtank and aquaria.Work funded under an Interagency Agreement between the U.S. Department of Energy and the U.S. Environmental Protection Agency under Contract No. DE-AS20-79 LC 01761 to the Rocky Mountain Institute of Energy and Environment, University of Wyoming.     

Ecotoxicity of copper to aquatic biota: a review

The toxic effects of copper on numerous aquatic flora and fauna has been studied intensely over the past 10 years. In general, there is a consensus that free cupric ions are more toxic if compared with other chemical forms such as organically complexed copper. Biological indicators exhibit a tremendously wide range of sensitivity to copper with toxic effects noted at pCu as low as 10 for some algae, while aquatic macrophytes appear to have a much higher tolerance for copper (pCu less than 5.0). The sensitivity of various groups of organisms seems discrepant and anomalous with accepted standards for drinking water and industrial discharges, and recommended rates of copper sulfate application to water bodies. The toxicity of copper, however, is mitigated by the presence of naturally occurring organic compounds in waters through complexation. The regulatory function of dissolved humic matter will continue to be a vital one for as long as copper is discharged into aquatic environments.     

Influence of tetrachloroethylene on the biota of aquatic systems: Toxicity to phyto- and zooplankton species in compartments of a natural pond

This study was designed to determine the effects of tetrachloroethylene on the phyto- and Zooplankton community at initial concentrations of 1.2 and 0.44 mg/L in separated compartments of an experimental pond. Measurements in the surrounding water were made simultaneously to detect possible effects of compartmentalization. Residues as low as 0.1 mg/L could be analyzed 5 days (low dose) and 38 days (high dose) post application. In all applied biotopes, a lethal effect on the Daphnia population was detected. The phytoplankton community showed an increase of relative abundance and a decrease in species diversity. Studies of the frequency distribution of six selected phytoplankton species demonstrated the total elimination of at least four species from the treated compartments. In spite of different dosing, only weak differences could be found in toxic effects between the low and high dosed compartments. No significant chemical-induced effect was observed on the physico-chemical properties of the treated water.     

Toxicity of alkyldinitrophenols to some aquatic organisms

Conclusions The toxicity of alkyldinitrophenols to juvenile Atlantic salmon increases with increasing octanol-water partition coefficient of these compounds. Some alkyldinitrophenols are extremely toxic to juvenile Atlantic salmon, larvae and adult lobsters, but comparatively nontoxic to crayfish. The unexpected low toxicity of dinoseb to crayfish is interesting also from the point of structure-activity relations and emphasizes the need of testing these in different species of aquatic fauna. No data are available on the levels of alkyldinitrophenols in fresh water, estuaries, and coastal areas. There is an indication that at least in certain streams the concentration may temporarily exceed many times the lethal threshold and have a severe impact on aquatic life. Alkyldinitrophenols are not likely to be bio-accumulated and biomagnified and their presence would not be detected by analyses of aquatic fauna. A detailed survey of their levels in surface waters, linked to their usage patterns, should be carried out.     

Toxicity of fluoroquinolone antibiotics to aquatic organisms

Toxicity tests were performed with seven fluoroquinolone antibiotics, ciprofloxacin, lomefloxacin, ofloxacin, levofloxacin, clinafloxacin, enrofloxacin, and flumequine, on five aquatic organisms. Overall toxicity values ranged from 7.9 to 23,000 microg/L. The cyanobacterium Microcystis aeruginosa was the most sensitive organism (5-d growth and reproduction, effective concentrations [EC50s] ranging from 7.9 to 1,960 microg/L and a median of 49 microg/L), followed by duckweed (Lemna minor, 7-d reproduction, EC50 values ranged from 53 to 2,470 microg/L with a median of 106 microg/L) and the green alga Pseudokirchneriella subcapitata (3-d growth and reproduction, EC50 values ranged from 1,100 to 22,700 microg/L with a median 7,400 microg/L). Results from tests with the crustacean Daphnia magna (48-h survival) and fathead minnow (Pimephales promelas, 7-d early life stage survival and growth) showed limited toxicity with no-observed-effect concentrations at or near 10 mg/L. Fish dry weights obtained in the ciprofloxacin, levofloxacin, and ofloxacin treatments (10 mg/L) were significantly higher than in control fish. The hazard of adverse effects occurring to the tested organisms in the environment was quantified by using hazard quotients. An estimated environmental concentration of 1 microg/L was chosen based on measured environmental concentrations previously reported in surface water; at this level, only M. aeruginosa may be at risk in surface water. However, the selective toxicity of these compounds may have implications for aquatic community structure.     

Profiles of polybrominated diphenyl ethers in aquatic biota

The profiles (concentrations scaled to a sum of 100) of polybrominated diphenyl ethers (PBDEs) in aquatic fauna differ from those of the commercial PBDE formulations, particularly by a much higher proportion of the congener 47. At the same time, the profiles reported by different authors vary a great deal and no patterns related to species, localities, etc. are obvious. It seems that there are systematic differences among the reporting laboratories, and measurement errors within the same laboratory may also play a role. However, the profiles of PBDEs in fish from the Baltic are very similar and form a tight "cluster". PBDE profiles in crustaceans appear different from those in fish.     

Toxicity of carbon nanotubes to freshwater aquatic invertebrates

Carbon nanotubes (CNTs) are hydrophobic in nature and thus tend to accumulate in sediments if released into aquatic environments. As part of our overall effort to examine the toxicity of carbon-based nanomaterials to sediment-dwelling invertebrates, we have evaluated the toxicity of different types of CNTs in 14-d water-only exposures to an amphipod (Hyalella azteca), a midge (Chironomus dilutus), an oligochaete (Lumbriculus variegatus), and a mussel (Villosa iris) in advance of conducting whole-sediment toxicity tests with CNTs. The results of these toxicity tests conducted with CNTs added to water showed that 1.00 g/L (dry wt) of commercial sources of CNTs significantly reduced the survival or growth of the invertebrates. Toxicity was influenced by the type and source of the CNTs, by whether the materials were precleaned by acid, by whether sonication was used to disperse the materials, and by species of the test organisms. Light and electron microscope imaging of the surviving test organisms showed the presence of CNTs in the gut as well as on the outer surface of the test organisms, although no evidence was observed to show penetration of CNTs through cell membranes. The present study demonstrated that both the metals solubilized from CNTs such as nickel and the "metal-free" CNTs contributed to the toxicity.     

Toxicity of five shale oils to fish and aquatic invertebrates

The chemical composition and toxicity of three shale crude oils (Tosco, Paraho, and Geokinetics), a hydrotreated oil (Paraho HDT), and a refined shale oil (Paraho JP-4) were assessed to determine the potential hazards to native fish species and food chain organisms posed by accidental spills of such materials. Colorado squawfish (Ptychocheilus lucius), fathead minnow (Pimephales promelas), cutthroat trout (Salmo clarki), and colonies of aquatic invertebrates were exposed to the watersoluble fractions of the shale oils for 96 hr to determine concentrations lethal to 50% of the exposed organisms (LC-50). The behavior of surviving fish was also measured to determine the sublethal influences of exposure. The composition of the five water-soluble fractions was similar to that of the crude and refined shale oils from which they were made. Hydrotreated and refined oils contained fewer aromatic compounds than the crude shale oils. The cutthroat trout, a species endemic to oil shale regions, was less tolerant of shale oil exposure than the other species tested; the LC-50 concentrations were 1.8 mg/L Geokinetics, 2.1 mg/L Tosco, and 1.3 mg/L Paraho. Exposure to concentrations of one-half to one-eighth those causing mortality reduced the swimming capacity of squawfish and significantly impaired their ability to capture prey. The number of invertebrate taxa, species, and organisms colonizing plate samplers declined with increasing oil concentration. The generaBaetis andIsoperla were most sensitive to shale oil exposure; significant mortality occurred at the lowest concentration (0.5–0.7 mg/L) tested for each shale oil.     

Toxicity of pesticides to aquatic microorganisms: a review

Microorganisms contribute significantly to primary production, nutrient cycling, and decomposition in estuarine eco-systems; therefore, detrimental effects of pesticides on microbial species may have subsequent impacts on higher trophic levels. Pesticides may affect estuarine microorganisms via spills, runoff, and drift. Both the structure and the function of microbial communities may be impaired by pesticide toxicity. Pesticides may also be metabolized or bioaccumulated by microorganisms. Mechanisms of toxicity vary, depending on the type of pesticide and the microbial species exposed. Herbicides are generally most toxic to phototrophic microorganisms, exhibiting toxicity by disrupting photosynthesis. Atrazine is the most widely used and most extensively studied herbicide. Toxic effects of organophosphate and organochlorine insecticides on microbial species have also been demonstrated, although their mechanisms of toxicity in such nontarget species remain unclear. There is a great deal of variability in the toxicity of even a single pesticide among microbial species. When attempting to predict the toxicity of pesticides in estuarine ecosystems, effects of pesticide mixtures and interactions with nutrients should be considered. The toxicity of pesticides to aquatic microorganisms, especially bacteria and protozoa, is an area of research requiring further study.