The toxic potential of four disinfectant agents (chlorine, ozone, peracetic acid and UV radiation), used in the disinfection of urban wastewater, was evaluated with respect to four aquatic organisms. ...Disinfection assays were carried out with wastewater from the city of Araraquara (São Paulo State, Brazil), and subsequently, toxicity bioassays were applied in order to verify possible adverse effects to the cladocerans (Ceriodaphnia silvestrii and Daphnia similis), midge larvae Chironomus xanthus and fish (Danio rerio). Under the experimental conditions tested, all the disinfectants were capable of producing harmful effects on the test organisms, except for C. xanthus. The toxicity of the effluent to C. silvestrii was observed to increase significantly as a result of disinfection using 2.5 mg L⁻¹ chlorine and 29.9 mg L⁻¹ ozone. Ozonation and chlorination significantly affected the survival of D. similis and D. rerio, causing mortality of 60 to 100 % in comparison to the non-disinfected effluent. In experiments with effluent treated with peracetic acid (PAA) and UV radiation, a statistically significant decrease in survival was only detected for D. rerio. This investigation suggested that the study of the ideal concentrations of disinfectants is a research need for ecologically safe options for the treatment of wastewater.
The mining sector has great importance to the economic activity in Brazil. However, it is also responsible for several environmental impacts such as the rupture of the Fundão dam (Mariana, Brazil) ...that resulted in the spillage of 50 million m
3
of mining tailings in the Doce River Basin. This study evaluated the acute and chronic effects of Fundão tailings on growth, development, respiration rates, swimming performance, and avoidance behavior of
Lithobates catesbeianus
tadpoles. Results showed that 96-h exposure to different dilutions (10, 25, 50, 75, and 100%) of a stock solution containing mining tailings (50 g/L) caused no mortality of tadpoles; however, the most concentrated solution decreased the swimming speed of the animals. After 16 days, tadpoles exposed to 25, 50, and 100% treatments had both swimming speed and distance traveled reduced. Oxygen consumption was also decreased in tadpoles exposed to the 100% solution after 20 days. Avoidance test indicated that tadpoles avoided lower tailing concentrations, but a reduced avoidance response was attested to the higher concentrations, probably due to the toxic effects of the residues that prevented animals’ displacement. Chemical analysis confirmed the occurrence of cadmium (Cd), lead (Pb), iron (Fe), manganese (Mn), zinc (Zn), and aluminum (Al) in Fundão tailings and its presence in the mouth and inside the intestine of treated tadpoles indicated the ingestion of metals by these organisms. This study showed that even presenting low lethal toxicity, long-term exposure to mining tailings from Fundão dam caused morphophysiological and behavioral damage in tadpoles.
► Abamectin is an acaricide, insecticide and nematicide. ► Effect of this contaminant on aquatic organisms from different trophic levels. ►Daphnia similis, Chironomus xanthus and Danio rerio. ► ...Abamectin was highly toxic at low concentrations, on the order of ngL−1 for zooplankton.
Abamectin is used as an acaricide and insecticide for fruits, vegetables and ornamental plants, as well as a parasiticide for animals. One of the major problems of applying pesticides to crops is the likelihood of contaminating aquatic ecosystems by drift or runoff. Therefore, toxicity tests in the laboratory are important tools to predict the effects of chemical substances in aquatic ecosystems. The aim of this study was to assess the potential hazards of abamectin to the freshwater biota and consequently the possible losses of ecological services in contaminated water bodies. For this purpose, we identified the toxicity of abamectin on daphnids, insects and fish. Abamectin was highly toxic, with an EC50 48h for Daphnia similis of 5.1ngL−1, LC50 96h for Chironomus xanthus of 2.67μgL−1 and LC50 48h for Danio rerio of 33μgL−1.
The continuous growth in global population since the beginning of the 20th century result in the necessity of food and energy provision favoring the intensive use of agricultural products such as ...pesticides. Although pesticides are important to prevent losses in the conventional chemically based agriculture, they frequently present side effects, which goes against agricultural production. The use of pesticides cause direct and indirect effects to soil organisms unbalancing essential soil processes (e.g. primary production, organic matter decomposition, nutrient cycling). Under tropical conditions, very little is known regarding the effects of pesticides to terrestrial organisms. Hence, the aim of the present study was to assess the ecotoxicological effects of the herbicide DMA® 806 BR (active ingredient: 2,4-D) and the insecticide Regent® 800 WG (active ingredient: fipronil), on terrestrial plant species (the dicot Raphanus sativus var. acanthioformis and the monocot Allium cepa), and soil invertebrates (the collembolan Folsomia candida and the enchytraeid Enchytraeus crypticus), using natural (NS) and artificial soils (TAS). For both pesticides, negative effects on non-target species were observed at concentrations lower than the doses recommended to prevent pests in sugarcane fields. For both soils, the dicot species was the most affected by the herbicide (R. sativus > A. cepa > F. candida > E. crypticus) and the collembolan species was the most affected by the insecticide (F. candida > E. crypticus = R. sativus = A. cepa). Although the order of the organisms’ sensitivity for both pesticides was the same in both soils, results showed that the extent of the effects was soil dependent. Considering the ecologically relevant concentrations tested, and their severe effects to non-target organisms, it may be concluded that the use of fipronil and 2,4-D under recommended conditions may pose a risk to the terrestrial environment.
•Recommended fipronil doses cause severe negative effects to terrestrial invertebrates.•Recommended 2,4-D doses cause severe negative effects to non-target plant species.•Relevant concentrations of pesticides cause risks for the terrestrial environment.•Fipronil and 2,4-D toxicity to terrestrial organisms depends on soil properties.
► We examine changes in the level of antioxidant enzymes, LPO in tissues of tilapia. ► An MT level was markedly higher. ► Antioxidant defensive system was related to input of metals in Monjolinho ...River.
The current study investigated oxidative stress parameters (enzymes activities, metallothionein content and lipid peroxidation) in freshwater fish, Oreochromis niloticus, tilapia exposure to Monjolinho River (in 4months of year: January, April, July and November). One critical site in Monjolinho River (site B) was assessed in comparison to a reference site (site A). Water pH and oxygen concentration was lower than that recommended by CONAMA (Brazilian National Environmental Committee), resolution 357/2005 for protection of aquatic communities, and ammonium and the metals Cu, Zn, Mn and Fe (on all months) concentrations were higher than the maximum concentration recommended. Glutathione peroxidase (GPx) and superoxide dismutase (SOD) activities were significantly decreased in liver and muscle in tilapia from Monjolinho River, throughout the year, in relation to reference except in gills that SOD activity increased. Glutathione S-transferase (GST) activity was significantly increased in liver of the tilapia from Monjolinho River in all sites, in relation to reference except in gills that GST activity increased in July and decreased in November, suggesting that GST activity could be induced to neutralize the pollutants toxicity. On the other hand, GST activity was significantly decreased in white muscle indicating a toxic effect of pollutants, resulting in a decreased ability of tilapia to perform defense reactions associated to GSTs. The decrease of catalase (CAT) activity in gills of the O. niloticus together with the increase of SOD activity, could explain the increased lipid peroxidation (LPO) level in this organ. Metallothionein levels in liver and gills were significantly high in all sites. Results indicate that the exposure to metals caused severe damage to tissues; despite the consensually assumed antioxidant induction as a sign of exposure to contaminants the effects seem in part to be mediated by suppression of antioxidant system with SOD, CAT and GPx as potential candidates for tissues toxicity biomarkers of pollutants.
Algal organic matter (AOM) in water reservoirs is a worldwide concern for drinking water treatment; once it is one of the main precursors for disinfection by-products formation (DBPs). In this ...context, this study investigated the ecotoxicity of DBPs from chlorination of AOM to
Ceriodaphnia silvestrii
and
Daphnia similis
(Crustacea, Cladocera)
.
The bioassays evaluated three scenarios, including the AOM extracted from
Chlorella sorokiniana
, the quenching condition used in the tests, and the DBPs formed after the chlorination of the two test waters with AOM (with and without bromide presence). The results showed that AOM has no toxic effects for the tested species under typical environmental concentration (5 mg∙L
−1
). However, since AOM is a potential precursor of DBPs, the toxicity of two test waters (TW-1 and TW-2) after the chlorination process (25 mg Cl
2
·L
−1
, for 7 days, at 20 °C) was tested. The sample with higher toxicity to the tested species was TW-1, in which chloroform and chloral hydrate were quantified (615 and 267 µg∙L
−1
, respectively). However, TW-2 showed lower concentration of chloroform and chloral hydrate (260 and 157 µg∙L
−1
, respectively), although bromodichloromethane, dibromochloromethane, and bromoform were also detected (464, 366, and 141 µg∙L
−1
, respectively). Although free chlorine is highly toxic to the tested species, the quenching conditions also affected the organisms’ survival due to the use of ascorbic acid and the presence of reaction intermediates. Nonetheless, both species were more affected by TW-1 and TW-2 than the quenching condition. These results endorse the importance of removing the AOM before the disinfection process to avoid the formation of DBPs. In addition, ecotoxicological analyses could provide a more comprehensive assessment of water quality, especially considering the challenges of quantifying DBPs and other emerging contaminants.
Graphical abstract
Highlights
• Algal organic matter (AOM) is a precursor of DBPs in chlorinated water.
• Environmental concentrations of AOM did not show toxicity to the two species.
• The quenching condition of free chlorine using ascorbic acid was toxic.
• Chlorination of AOM formed DBPs concentrations toxic to the cladocerans.
• Among the five detected DBPs, chlorinated species were more toxic than brominated.
Despite that chironomids are the most widely used benthic insect test species worldwide, little research has been conducted so far with tropical chironomid representatives. This study was designed to ...evaluate the indigenous midge
Chironomus sancticaroli
as a candidate test species for use in tropical toxicity assessments. To this end, laboratory water-only toxicity tests were conducted evaluating copper and cadmium. Obtained lethal concentration values were overall comparable or lower than those reported for other chironomids, including those most commonly used in temperate regions (
C. riparius
and
C. dilutus
). In addition,
C. sancticaroli
was deployed in situ in the Monjolinho River (São Paulo State, Brazil), and toxicity of sediment from this river was evaluated in the laboratory. Several field water and sediment quality parameters also were measured to enable correlating these with the effects observed in these toxicity tests. Field sediment toxicity to
C. sancticaroli
appeared to be related with sediment endosulfan concentrations, whereas effects noted in the in situ test were likely due to low pH values measured in river water.
Chironomus sancticaroli
appears to be a suitable candidate for inclusion as a test species in tropical toxicity evaluations in both the laboratory and the field.
Parabens, a group of preservatives with a wide industrial range, threaten human and aquatic biota health due to their toxicity and endocrine disruption potential. As conventional wastewater treatment ...may not be enough to keep natural environments safe, toxicity studies are useful tools for supporting ecological risk assessments. Here, we focused on assessing ethylparaben’s, one of the most common kinds of paraben, toxicity in the cladocerans
Daphnia similis
and
Ceriodaphnia silvestrii
. The EC
50
sensitivity for
D. similis
and
C. silvestrii
was 24 (21–28) mg L
− 1
and 25 (19–33) mg L
− 1
, respectively. Inhibition of reproduction and late development of females were observed in
C. silvestrii
exposed to 8 mg L
− 1
. Furthermore, species sensitivity distribution was used to assess ecological risk, and ethylparaben demonstrated low potential risk for aquatic biota.
Widely used in agricultural fields, fipronil acts in the arthropods’ nervous systems. Although advances have been noticed, little is known about the effects of the insecticide to non-target soil ...organisms, especially considering specific parameters from tropical environments. This is the first study considering ecologically relevant tropical conditions to assess the environmental risk of fipronil to the terrestrial ecosystem. The present study aimed to estimate fipronil’s ecological risk to soil organisms through a tiered approach. At the screening level (TIER I) data were obtained from both the literature and laboratory experiments. For the intermediate level (TIER II), species sensitivity distributions (SSD) curves were generated based on ecotoxicological data from six species of soil invertebrates in two soil types. To estimate the risk, the Toxicity-Exposure Ratios (TER) were calculated at each tier considering the related toxicity data and the fipronil concentrations, which were measured and predicted in the field. Results showed that ecologically relevant concentrations of fipronil lead to a high risk for the edaphic community (above 100 times higher than the established safety value). The high risks were observed for both tiers, although at TIER II (SSD approach) it was at least 2.5 times higher than at TIER I. It was also discussed here that the pesticide mode of action is the factor most influencing toxicity; the estimated risk considering artificial soil was comparable to that with the natural soil; and estimating risk using only one species (as performed in the tropics) may underestimate the risk to the edaphic community.
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