Ecotoxicological Tests Research Articles

Ecotoxicity of marine sediments: Sampling and laboratory artifacts and their impacts on risk classification

Assessing the ecotoxicological risk of marine sediments is now a critical factor in deciding how to treat dredged material in harbor and coastal areas. Although ecotoxicological analyses are routinely required by some regulatory agencies in Europe, laboratory skills necessary to perform them are often underestimated. According to the Italian Ministerial decree No. 173/2016, ecotoxicological tests are performed on the solid phase and elutriates, and the classification of sediment quality is defined using the “Weight of Evidence” (WOE) approach. However, the decree does not provide adequate information regarding the preparation techniques and laboratory skills. As result, a wide variability among laboratories occurs. An error in the classification of ecotoxicological risk has a negative impact on the whole environmental quality and/or the economy and management of the interested area. Thus, the main aim of this study was to determine if such variability can affect the ecotoxicological outcomes of tested species and WOE associated classification, producing different options for the management of dredged sediments. Four different sediment types were selected to assess the ecotoxicological responses and their changes as a function of variability of the following factors: a) the storage time laps (STL) for both the solid phase and the elutriates; b) the methods used to prepare the elutriates (centrifugation vs. filtration), and the conservation method used for the elutriates (freshly prepared vs. freezing). Results suggest a wide variability of ecotoxicological responses among the four sediment samples here considered, differentiated according to chemical pollution, grain-size texture, and macronutrient contents. The storage time laps significantly affect the physicochemical parameters and the ecotoxicity of both the solid phase test and elutriates. For the elutriates preparation, centrifugation is preferred to filtration to preserve a better representation of sediment heterogeneity. Freezing of elutriates does not seem to show any significant effects on the toxicity. Findings allow to define a weighted schedule of the storage time of sediments and elutriates useful for laboratories to scale analytical priority and strategies related to different sediment types.

An Easy-to-Use Histological Technique for Small Biological Samples of Senegalese Sole Larvae

Histological techniques are a traditional and essential tool for adequately comprehending cellular morphology and physiology in several scientific fields, including ecotoxicological studies. Although bioassays generally recommend using small test organisms, based on advantages such as low maintenance costs and the possibility of a higher number of replicates, the histological process of such organisms is still challenging due to the difficulty of handling them. The present study proposes an accessible protocol for performing the histology of a biological sample of 8 mm maximum length and using histopathological biomarkers in Senegal sole larvae for ecotoxicological tests. Eight-day old larvae of Solea senegalensis obtained from breeders’ natural spawns in cultivation conditions were submitted to histological processing by an adjusted protocol comprising fixation, agarose array pre-embedding, dehydration, paraffin embedding, slides’ preparation, and image analysis by light optical microscope coupled to a digital camera. Low-cost and easy-to-use alternatives were applied in the technique execution. The histological steps were detailed, and S. senegalensis morphological features were presented. This can be considered valuable background information for ecotoxicological studies where changes in cell morphology and physiology are expected.

Sustainable agricultural use of sewage sludge: impacts of high Zn concentration on on Folsomia candida, Enchytraeus crypticus, Lactuca sativa, and Phaseolus vulgaris.

Zinc (Zn) is an essential micronutrient for plants and an important component for maintaining soil quality. Commonly found in the soil due to anthropogenic activities, such as industrialization and application of organic waste as fertilizers, in high concentrations, Zn may induce soil toxicity, affecting important communities, such as edaphic fauna. Despite its high concentrations found in the environment, Zn bioavailability can be affected by the type of soil, organic matter content and pH. In this work, Zn had its toxicity evaluated in a natural tropical soil, sampled in São Paulo-Brazil, for two soil invertebrates (Folsomia candida, Enchytraeus crypticus) and two seeds (Lactuca sativa and Phaseolus vulgaris), through ecotoxicological tests. The invertebrate E. crypticus was exposed to Zn concentrations of 10.0 (T1); 100.0 (T2); 150.0 (T3); 200.0 (T4); 400.0 (T5) mg Zn kg-1 of dry soil, while F. candida, L. sativa and P. vulgaris were exposed to Zn concentrations of 100.0; 200.0; 400.0; 800.0 (t6); 1600.0 (t7); and 2000.0 (t8) mg Zn kg-1 of dry soil. The outcome evaluated were seed germination, for L. sativa and P. vulgaris, and reproduction, for F. candida and E. crypticus. The EC50 obtained for E. crypticus, F. candida, L. sativa, and P. vulgaris were 261.5, 1089.7, 898.5, and 954.5mg Zn kg-1 of dry soil, respectively, being E. crypticus the most sensitive organism, and only at the highest Zn's concentrations the organisms' reproduction and seeds' germination showed a statistically significant inhibitory effect (p < 0.05). Therefore, this work's results showed that Zn does not present significant toxicity for the tested soil organisms and seeds and that at 100mg Zn kg-1 of dry soil it can be beneficial to F. candida and E. crypticus' reproduction and L. sativa's germination. These results imply that the presence of Zn in low concentrations, both in soil and biofertilizers, such as sewage sludge, not only is not a concern, but it can even benefit certain crops and functions of edaphic organisms, which may contribute to the engagement of sustainable agricultural practices and the quest for food security.

Chironomus sancticaroli (Diptera: Chironomidae) in ecotoxicology: laboratory cultures and tests.

Chironomus sancticaroli is a tropical species, easy to grow and to maintain in laboratory cultures. It has a fast reproduction cycle, under adequate conditions, around 30 days, allowing it to have many generations per year, an important criterion for selecting a test organism in ecotoxicology. Its life stages include: eggs, four larval instars (one planktonic and three benthic), pupa and adult (midges) This study aimed to: (1) review the methods for C. sancticaroli cultivation and its use in ecotoxicological tests, (2) establish a laboratory culture of C. sancticaroli, presenting the difficulties and discussing the ways to overcome them. Early 4th instar larvae was the most used in acute studies, while the 1st instar larvae (early 1st instar) was the most used in chronic studies; 96 h and 28 days were the most frequent durations in acute and chronic studies, respectively. The most common endpoints evaluated were organisms' survival and development, and most of the ecotoxicological studies using C. sancticaroli were performed in laboratory. Most of the tested contaminants were pesticides and these had the most adverse effects on organisms. Most mesocosms with environmental contaminated samples did not show adverse effects on C. sancticaroli. Chronic and field studies as well as those testing the effects of the mixture contaminants on C. sancticaroli were still deficient. Keeping the laboratory environment and equipment effectively sanitized was important as well as maintaining stabilized conditions of temperature, photoperiod, physical, chemical and biological water quality in cultures.

An innovative methodological path to attribute the hazard property HP14 “ecotoxic” to waste using a weight of evidence approach

The criteria for the application of hazard property code HP14 “ecotoxicity” to waste assessment have been defined by the Council Regulation (EU) 2017/997. However, on the basis of available methodologies, its application may present some issues. Those can be referred to the preparation and representativeness of the sample to be analyzed, to the chemical evaluation by the summation method (CLP Regulation), to the toxicity thresholds of ecotoxicological tests and the evaluation of the real environmental impact of waste. In this work an integrated chemical and ecotoxicological approach, that relies on modified synthetic indices previously developed for dredging sediment management is proposed. The methodological procedure, assuming that the eluate represents the most relevant carrier of contaminant into the environment, was applied on eluates extracted from samples of 3 kinds of waste categories (car-fluff, fly-ash and sludges), introducing changes starting from the sample preparation and the targeted ecotoxicological and chemical analyses. The application of this approach allowed qualifying the sludge and part of fly-ash samples as “non ecotoxic”, unlike the conventional method (CLP) under which all waste categories considered were found to be “ecotoxic”. The new pathway for waste qualification, abandoning the classical tabular approach based on mere chemical concentrations and/or predetermined thresholds of toxicity (principle of the worst case), showed a greater discriminatory power among samples with different characteristics, and a more realistic and quantitative assessment of the environmental impact which can be caused by leaching of the waste.

Minimizing Experimental Testing on Fish for Legacy Pharmaceuticals.

There was no regulatory requirement for ecotoxicological testing of human pharmaceuticals authorized before 2006, and many of these have little or no data available to assess their environmental risk. Motivated by animal welfare considerations, we developed a decision tree to minimize in vivo fish testing for such legacy active pharmaceutical ingredients (APIs). The minimum no observed effect concentration (NOECmin, the lowest NOEC from chronic Daphnia and algal toxicity studies), the theoretical therapeutic water concentration (TWC, calculated using the fish plasma model), and the predicted environmental concentration (PEC) were used to derive API risk quotients (PEC/NOECmin and PEC/TWC). Based on a verification data set of 96 APIs, we show that by setting a threshold value of 0.001 for both risk quotients, the need for in vivo fish testing could potentially be reduced by around 35% without lowering the level of environmental protection. Hence, for most APIs, applying an assessment factor of 1000 (equivalent to the threshold of 0.001) to NOECmin substituted reliably for NOECfish, and TWC acted as an effective safety net for the others. In silico and in vitro data and mammalian toxicity data may further support the final decision on the need for fish testing.

Integrated Analytical Approach: An Added Value in Environmental Diagnostics

Environmental diagnostics are commonly used to identify anthropogenic influences in various environmental settings. However, the use of a single survey technique is limiting and leads to an incomplete and often inaccurate picture of reality. In this study, three real cases analyzing impacts on marine ecosystems have been presented to prove how the integration of different diagnostic techniques can be very beneficial to better understand the phenomena that occur as well as the impacts and associated damages. Studies combining classical diagnostics based on the determination of contaminant levels by chemical analysis, ecotoxicological tests and stress biomarkers with diagnostics by Field Emission Scanning Electron Microscopy-FESEM and X-ray diffraction-XRD microscopy are reported. Findings suggest that the embedding of chemical analyses, ecotoxicology and microchemical FESEM and XRD analyses allow us to hit the mark and give precise and effective responses in environmental management.

Improved methods for quantifying soil invertebrates during ecotoxicological tests: Chill comas and anesthetics

Soil invertebrate ecotoxicological tests are important when making informed site-management decisions. However, traditional tests are time-consuming and require quantification of high numbers of soil invertebrates burrowed beneath the surface of soil. A commonly used technique to extract invertebrates from the soil is the floatation method. Due to the movement of Collembola, and the presence of small soil particulates and bubbles on the surface of the water, automatic image analysis software may inaccurately quantify the true number of individuals present. Hence, manual counting immediately following extraction, or from images, is still the most effective method utilized for quantifying floated soil invertebrates. This study investigated three novel techniques; the use of an ice-water bath, chest freezer (−12 °C) and ethanol to temporarily immobilize groups of 35 Folsomia candida individuals to increase accuracy during the quantification step. Active thermography to aid automatic image analysis was also investigated. Results show that while thermoimaging did not provide a distinct advantage in differentiating soil invertebrates from soil particles, both an ice-water bath and 4.75% ethanol solution were extremely effective at temporarily immobilizing F. candida with no apparent ill effects. The outcome of this study will assist future soil invertebrate research by increasing the accuracy of invertebrate quantifications. In addition, as the techniques caused no mortality to the invertebrates, the same individuals remain available for continuous monitoring experiments, repeated exposure, and/or multi-generational studies.

Recommended rates of azoxystrobin and tebuconazole seem to be environmentally safe but ineffective against target fungi

The use of fungicides in agriculture has been playing a role in the enhancement of agricultural yields through the control of pathogens causing serious diseases in crops. Still, adverse environmental and human health effects resulting from its application have been reported. In this study, the possibility of readjusting the formulation of a commercial product combining azoxystrobin and tebuconazole (active ingredients – AIs; Custodia®) towards environmentally safer alternative(s) was investigated. Specifically, the sensitivity of non-target aquatic communities to each AI was first evaluated by applying the Species Sensitivity Distributions (SSDs) approach. Then, mixtures of these AIs were tested in a non-target organism (Raphidocelis subcapitata) denoting sensitivity to both AIs as assessed from SSDs. The resulting data supported the design of the last stage of this study, where mixtures of those AIs at equivalent vs. alternative ratios and rates as in the commercial formulation were tested against two target fungal species: Pyrenophora teres CBS 123929 and Rhynchosporium secalis CBS 110524. The comparison between the sensitivity of non-target aquatic species and the corresponding efficacy towards target fungi revealed that currently applied mixture and rates of these AIs are generally environmentally safe (antagonistic interaction; concentrations below the EC1 for R. subcapitata and generally below the HC5 for aquatic non-target communities), but ineffective against target organisms (maximum levels of inhibition of 70 and 50% in P. teres CBS 123929 and R. secalis CBS 110524, respectively). Results additionally suggest a potentiation of the effects of the AIs by the other formulants added to the commercial product at tested rates. Overall, this study corroborates that commercial products can be optimized during design stages based on a systematic ecotoxicological testing for ingredient interactions and actual efficacy against targets. This could be a valuable pathway to reduce environmental contamination during transition to a more sustainable agricultural production.

Relevance of Pyrolysis Products Derived from Sewage Sludge for Soil Applications

The recovery of sludge produced in the wastewater treatment process in WWTPs is often limited by the high content of toxic forms of contaminants of both an inorganic and organic nature. One of the options for the effective treatment of the world’s ever-increasing quantities of sewage sludge is the pyrolysis process. Thermochemical conversion of sewage sludge is emerging as a promising method for treating these heterogeneous and highly complex wastes with increasing research work. Pyrolysis-treated sewage sludge (PM) prepared at 603–615 °C was characterized by pH, EC, and CHN-S analysis; total and bioavailable concentrations of P and heavy metals (Cd, Cu, Fe and Zn); fractionation of bound forms of P and heavy metals in the material and determination of the presence of polycyclic aromatic hydrocarbons (PAHs). The studied material was subjected to ecotoxicological tests (Daphnia pulex L.) and cultivation tests (Lactuca sativa L.). Elemental analysis revealed the concentrations of heavy metals in PM: Fe (137,600 mg/kg), Zn (2602 mg/kg), Cu (582 mg/kg), Cr (107 mg/kg), Pb (87 mg/kg), Ni (67 mg/kg), As (&lt;1 mg/kg), Hg (&lt;2 mg/kg) and Cd (&lt;1 mg/kg). The highest values of extractability of the investigated heavy metals from PM were found in the cases of Zn (HCl) and Fe (Mehlich 3), both values not exceeding 500 mg/kg. BCR sequential extraction showed the major concentrations of Cu and Fe were predominantly bound in the residual fraction (F4) and Zn in the reducible fraction (F2) of PM. The results of heavy metal bioavailability suggest that the addition of PM does not negatively affect the growth of lettuce biomass and the metal contents of plant tissues. Based on the results obtained, the pyrolysis material prepared from municipal sewage sludge seems to be a promising and innovative soil additive and a potential alternative to conventional inorganic fertilizers.

A Roundup herbicide causes high mortality and impairs development of Chrysoperla carnea (Stephens) (Neuroptera: Chrysopidae)

Glyphosate has and is being used extensively in herbicide formulations worldwide. Thus, glyphosate-based herbicides (GBH) substantially add to the environmental load of pesticides and warrant a strict risk assessment. Ecotoxicological testing of herbicides focuses on non-target plants and higher animals while direct effects on arthropods are only cursory tested on the premise of contact exposure. However, oral exposure, as we show in our case, can be highly relevant for systemic pesticides, such as GBH. Specifically, in crop systems including genetically modified crops that are tolerant to GBH, these herbicides and their breakdown products are present both internally and externally of the crop plants and, therefore, are ingested by the crop-associated arthropod fauna.We tested the effects of oral uptake of the Roundup formulation WeatherMax on larvae of the lacewing Chrysoperla carnea, a model organism in ecotoxicity testing programs. Long-term oral exposure of C. carnea larvae throughout its juvenile life stages was tested with concentrations ranging from 0.001 to 1 % dilution, thus, lower than the 1.67 % recommended for field applications. Inhibition of metamorphosis was observable at 0.1 % but at a concentration of 0.5 %, GBH significantly impaired cocoon formation and led to massive lethal malformations. At GBH concentration of 1 % half of the individuals remained permanent larvae and no adult hatched alive. The effects observed followed a clear dose-response relationship.The hazard caused by direct insecticidal action of GHB after oral uptake is highly relevant for the environmental safety and reveals a gap in regulatory risk assessments that should urgently be addressed, specifically in light of the on-going insect decline.

Ecotoxicity Study of Additives Composed of Zinc and Boron.

The high use of additives containing zinc borate and their limited solubility in water both lead to its persistence and accumulation in biological systems. On the other hand, soluble forms of boron are easily available to plant roots and are taken up by plants. There are no ecotoxicological data available for zinc borate, the industrial utilization of which is widespread. Therefore, the potential toxicity of zinc borate and its dissociated compounds was evaluated. Based on two different ecotoxicology tests, their effect on plant growth was studied. Firstly, the impact on Lemna minor growth was investigated, including the effect on pigment content. Secondly, the inhibition of the root growth of higher plant species Sinapis alba (mustard), Lactuca sativa (lettuce) and Trifolium pretense (clover) was measured. The growth inhibition test on L. minor was more complex and sensitive compared to the plant seed germination test. Already low concentrations (10 mg/L) of ZnO, B2O3 and Zn3BO6 led to a decrease in frond growth and to an inhibition of the conversion of chlorophyll a to chlorophyll b. These results suggested that the stress caused by these additives caused damage to the photosynthetic apparatus. The highest inhibition of frond growth was detected in fronds treated with B2O3 (92-100%). In ZnO and Zn3BO6, the inhibition of frond growth was between 38 and 77%, with Zn3BO6 being slightly more toxic. In the seed germination test, the most sensitive species was lettuce, the growth of which was inhibited by 57, 83 and 53% in ZnO, B2O3 and Zn3BO6 treatments, respectively. However, the inhibitory effect on each plant was different. In lettuce and clover, the seed germination and root elongation decreased with increasing element concentrations. In contrast, in mustard, low concentrations of ZnO and Zn3BO6 supported the growth of roots. For that reason, more complex tests are essential to evaluate the additive toxicity in the environment.

Surrogate species in pesticide risk assessments: Toxicological data of three stingless bees species

Discussions about environmental risk reassessment of pesticides have grown in the last decades, especially in tropical and subtropical regions since the diversity of bee species in these places is quite different. Stingless bees are highly affected by pesticides, and toxicity information is necessary to include them in the regulatory process of countries that hosts a diversity of these species. Therefore, the present study aimed to evaluate the Median Lethal Concentration (LC50), estimate the Median Lethal Dose (LD50) and compared the sensitivity of three species of stingless bees exposed to the commercial formulation of the neonicotinoid thiamethoxam (TMX). The LD50 was estimated based on the LC50 determined in the present study (LC50 = 0.329 ng a.i./μL for Tetragonisca angustula; 0.624 ng a.i./μL for Scaptotrigona postica, and 0.215 ng a.i./μL for Melipona scutellaris). Considering these data, toxicity endpoints were used to fit species sensitive distribution curves (SSD) and determine the sensitivity ratio. The results showed that all the stingless bees tested are more sensitive to TMX than the Apis mellifera, the model organism used in ecotoxicological tests. Regarding the oral LC50, the most susceptible and most tolerant species were M. scutellaris > T. angustula > S. postica > A. mellifera. Following the same evaluated pattern, for the LD50 (considering the weight of the bees - ng a.i./g bee), we have: M. scutellaris > S. postica > T. angustula > A. mellifera, and without the weight considered (ng a.i./bee): T. angustula > M. scutellaris > S. postica > A. mellifera. The different sensitivities among stingless bee species highlight the importance of inserting more than one surrogate species with a variety of sizes in research and protocol development. Additionally, the research suggests the need to investigate patterns regarding the influence of body mass on pesticide sensitivity among stingless bee species.

Ecotoxicological characterization of engineered biochars produced from different feedstock and temperatures

Biochar (BC) engineering, which has recently gained a lot of interest, allows designing the functional materials. BC modification improves the properties of pristine biochar, especially in terms of adsorption parameters. An interesting type of modification is the introduction of metals into the BC's structure. There is a knowledge gap regarding the effects of modified BC (e.g., BC-Mg, BC-Zn) on organisms. The aim of this study was the ecotoxicological evaluation of BC-Mg and BC-Zn composites, received under diverse conditions from willow or sewage sludge at 500 or 700 °C. The ecotoxicological tests with bacteria Vibrio fischeri (V. fischeri) and invertebrates Folsomia candida (F. candida) were applied to determine the toxicity of BC. The content of toxic substances (e.g., polycyclic aromatic hydrocarbons (PAHs), heavy metals (HMs), environmentally persistent free radicals (EPFRs)) in BC were also determined and compared with ecotoxicological parameters. The ecotoxicity of studied BCs depends on many variables: feedstock type, pyrolysis temperature and the modification type. The Zn and Mg modification reduced (from 28 to 63 %) the total Ʃ16 PAHs content in willow-derived BCs while in SL-derived BCs the total Ʃ16 PAHs content was even 1.5–3 times higher compared to pristine BCs. The Zn modified willow-derived BCs affected positively on F. candida reproduction but showed inhibition of luminescence V. fischeri. BC-Mg exhibited harmful effect to F. candida. The ecotoxicological assessment carried out sheds light on the potential toxicity of BC-Zn and BC-Mg composites, which are widely used in the removal of heavy metals, pharmaceuticals, dyes from waters and soils.

The validation of converting pyrite ash-contaminated soil into End-of-Waste by the High-Performance Solidification/Stabilization process application.

One of the major challenges to establishing more sustainable management strategies than landfill disposal of metals-contaminated soils is the lack of End-of-Waste (EoW) criteria defined at the European and national levels. Another limitation stems from the scarcity of information on industrial-scale applications of treatment technologies able to obtain safe and reusable materials from such contaminated waste. In this context, the High-Performance Solidification/Stabilization process was applied for the full-scale remediation of pyrite ash-contaminated soil (ca. 24 000 m3 ), and a dedicated sampling and analytical protocol was developed and implemented to verify if the treated material obtained complied with the general EoW criteria established by article 6 of the Waste Framework Directive 2008/98/EC. The results of the leaching, ecotoxicological, and mechanical tests carried out on representative samples of the treated soil showed that this material (ca. 19 000 m3 ) could be classified as EoW and thus was deemed reusable both in-situ as filler for the excavation and ex-situ as road construction material. These results improve the knowledge of the performance of a state-of-the-art technique for the treatment of metals-contaminated soil. Furthermore, the developed monitoring plan can support future assessments on the compliance of materials obtained from contaminated soil with the general EoW criteria. Integr Environ Assess Manag 2023;19:961-969. © 2022 SETAC.

Chronic and transgenerational effects of silver nanoparticles in freshwater gastropod Lymnaea stagnalis

Traditional ecotoxicological studies prove to be focused mainly on single-generation, multigenerational research in ecotoxicological testing is needed to improve the predictive approaches in ecological risk assessment. Silver nanoparticles (AgNPs) have been increasingly detected in aquatic environments due to their extensive use in consumer products. We investigated the transgenerational effects of AgNPs on the life traits of freshwater model gastropods Lymnaea stagnalis for two generations. The reversibility of the effects of using recovery experiments was also performed. Results showed that AgNPs induced high Ag bioaccumulation in the whole soft tissues of parental L. stagnalis after 21 days of exposure. The increased ROS production and reduced condition index and fecundity were found after exposure to AgNPs at 500 μg/L. These results highlight that under AgNPs exposure, adult gastropods might allocate more resources to resist oxidative stress rather than to growth or reproduction. Furthermore, the Ag accumulation and ROS production of egg clutches were significantly related to parental exposure duration and concentrations. On the other hand, isolated eggs exposure demonstrated biological effects were persistent in terms of the next generation. For example, after transfer to a clean medium, similar Ag bioaccumulation and ROS production were observed from eggs which parents were pre-exposed to 50 and 500 μg/L AgNPs. Current explicit consideration of offspring performance adds value to existing toxicity testing protocols. Parental exposure duration has important implications for offspring effects, and parental exposure can cause transgenerational changes in resistance that have significant implications for toxicity testing and adaptive responses. These effects across generations point out the need for multigenerational tests to assess the environmental risk of MNPs in aquatic organisms.

Long life at low temperatures – The life-history of Folsomia candida at ecological relevant temperatures

Collembola are among the most abundant terrestrial microarthropods and are widely used in ecotoxicological testing since they are important for soil ecosystem processes (Fountain and Hopkin 2005). In their natural environment, these arthropods are often exposed to varying temperatures (Smit and Van Gestel 1997; Fountain and Hopkin 2005; Bindesbøl 2008). However, when applied as a model organism for ecotoxicological testing, experiments are performed at 20 °C; Smit and Van Gestel 1997; International Organization for Standardization (ISO) 1999; OECD 2009). The temperature choice might be beneficial concerning the timeline of these 28-day experiments (e.g., covering juvenile phase, first reproduction, and first generation hatching) but does not reflect the reality in the field. Variable climate can influence the functioning of organisms and thereby induce changes in susceptibility for toxicant stress (Smit and Van Gestel 1997; Bindesbøl 2008; de Boer et al. 2010). The presented study aims to investigate: (1) longevity of F. candida at different temperatures; (2) reproduction of the species also under different temperatures. Two different test designs were developed, each aiming to analyse a different aspect of the life cycle of F. candida. The results showed that temperature has a significant impact on the life-history traits, longevity, and reproduction of Folsomia candida. Temperatures below the standard of 20 °C significantly increased the life span up to 922.5 days at 4 °C. Furthermore, our results highlight the effect of temperature on developmental processes, such as hatching time and maturation.

Ecotoxicological Evaluation of Dye Degradation and Photodegradation by Peracetic Acid with Sodium Carbonate

Advanced oxidative processes (AOPs) are procedures used for the treatment of wastewater based on the generation of free radicals, such as hydroxyl (•OH) and carbonate anion (CO3•−) radicals. However, although contaminants are degraded in these processes, the by-products generated in this transformation can be a greater source of toxicity than the original compound, making ecotoxicological tests essential for monitoring the efficacy of these treatment processes. In this study, we examined the ecotoxicity of AOP by-products generated using peracetic acid (PAA) and sodium carbonate, with and without solar radiation, for the degradation of methylene blue dye, using the planarian Girardia tigrina as a test organism. Ecotoxicological tests evaluated the acute toxicity of the generated by-product in terms of lethal concentrations (LC50). Although in both assays the degradation of the dye was greater than 99%, higher toxicity was observed in the assay using PAA and carbonate in the absence of radiation. From the results obtained, we conclude that the by-product generated from the degradation of methylene blue dye by peracetic acid and sodium carbonate, with and without solar radiation, can pose risks to aquatic ecosystems if released directly into water bodies.

Vermicomposting as a Sustainable Option for Managing Biomass of the Invasive Tree Acacia dealbata Link

The tree Acacia dealbata is native to Australia but has become invasive in many parts of the world thanks to its N-fixing capacity and to the allelopathic compounds present in its biomass. We conducted a pilot-scale study to assess the potential conversion of A. dealbata biomass by vermicomposting via the earthworm Eisenia andrei. The flowering aerial A. dealbata biomass was shredded and placed in a vermireactor under greenhouse conditions for 56 days. The vermicomposted material was sampled every two weeks to analyse its biological and chemical parameters. The phytotoxicity of the fresh A. dealbata material and vermicompost was assessed via an ecotoxicological test with Lepidium sativum seeds. The activity of the earthworms caused strong modifications of the properties of the processed material: the electric conductivity, basal respiration, and organic matter content were reduced, whereas the concentrations of other elements such as N, P, or Zn increased. The earthworm biomass increased steadily until day 42 and then decreased, probably due to the depletion of labile organic matter during the initial stages of vermicomposting. The fresh A. dealbata material reduced the germination and radicle elongation of L. sativum, whereas vermicompost showed the same values as control. The produced vermicompost was an organic fertiliser rich in N and was not phytotoxic. Vermicomposting provides an opportunity to create a new value chain for the control of the invasive tree A. dealbata.

Abatement of the ecotoxicological risk of landfill leachate by heterogeneous Fenton-like oxidation

Landfill leachates are highly contaminated liquid waste, and their treatment and detoxification are a challenging task. The current system of ecotoxicological risk assessment is complex and time-consuming. It is of fundamental importance to develop simpler and faster tools for the evaluation of the treated liquid waste and for an easier preliminary screening of the most active catalytic formulation/reaction conditions of the Fenton-like process. Here, several analytical techniques have been used for the assessment of the reduction of toxicity of the landfill leachate after Fenton process over copper-zirconia catalyst (ZrCu). Ultraviolet–visible (UV–vis) spectroscopy and absorbable organic halogens (AOX) analysis have been coupled to achieve further insight into the degradation of contaminants. In addition, for the first time, the qualitative abatement of organic compounds is monitored through proton nuclear magnetic resonance (1H NMR) analysis, providing a new method for evaluating the effectiveness of the treatment. Spectroscopic techniques reveal that the Fenton process induces a significant abatement of the aromatic and halogen compounds (51%) in the landfill leachate with a reduction of the toxicity that has been confirmed by ecotoxicological test with algae. These results validate the investigated tool for a simple rapid preliminary evaluation of the detoxification efficacy.