Earthworm Mortality Research Articles

Ecotoxicological evaluation of dredged sediments from Rodrigo de Freitas Lagoon (Rio de Janeiro State, Brazil) using bioassays with earthworms and collembolans

The toxicity and metal bioavailability were studied in dredged sediments from Rodrigo de Freitas Lagoon (Rio de Janeiro, RJ, Brazil) using acute and avoidance tests with Eisenia andrei, and reproduction tests with Folsomia candida. The sediment was mixed with an artificial soil, and two natural soils (ferralsol and chernosol—representative Brazilian tropical soils) to obtain the following doses: 1, 3, 6, 12, 18, 24 and 30%. Total metal concentrations were determined in the sediment to support the interpretation of ecotoxicological data. Metal concentrations in the mixtures were in agreement with the threshold limits established by Brazilian law. However, significant avoidance responses were found on doses ≥ 3% and were the most sensitive endpoint. Earthworm mortality found in artificial soil mixtures (LC50 = 3.9) suggests higher toxicity levels than those obtained in ferralsol (LC50 = 7.6%) and chernosol (11.0%) treatments. Earthworm mortality, avoidance responses and collembolan reproduction levels found in ferralsol mixtures (LC50 = 9.2; avoidance EC50 = 2.3%; reproduction EC50 = 2.8%) were higher compared to chernosol treatments (LC50 = 11.0%; avoidance EC50 = 4.3%; reproduction EC50 = 4.9%). The reduction of toxicity levels in chernosol mixtures is probably due to the abundance of expansive clay minerals in chernosols with capacity of adsorbing metals and other xenobiotic substances from soil pore water, decreasing metal bioavailability. Finally, threshold limits defined by Brazilian legislation for soil quality and land disposal of dredged sediments are not sufficient to prevent noxious effects on soil fauna and should be complemented with a preliminary ecotoxicological evaluation.

Summary of historical terrestrial toxicity data for the brominated flame retardant tetrabromobisphenol A (TBBPA): effects on soil microorganisms, earthworms, and seedling emergence.

This article summarizes historical and recent research on the terrestrial toxicology of tetrabromobisphenol A (TBBPA). Despite its ubiquitous use and presence in the environment, little published data is available to evaluate the terrestrial ecotoxicity of TBBPA. The purposes of this paper are to enable broad access to a series of TBBPA ecotoxicity tests (nitrogen transformation, earthworm survival/reproduction, and seedling emergence/growth) that were conducted in support of regulatory risk assessments, and to summarize available research in the terrestrial toxicity of TBBPA. In these studies, no significant effect of TBBPA on nitrogen transformation was observed up to the highest concentration [1000mg/kg dry weight (d.w.) soil]. The no-observed-effect concentrations (NOECs) for seedling emergence ranged from 20 to 5000mg/kg d.w. Sensitivities were soybeans < corn ≈ onion ≈ tomato < ryegrass < cucumber; the most sensitive endpoints being seedling dry weight and height. The 28-day earthworm mortality NOEC was > 4840mg/kg d.w. The most sensitive terrestrial endpoint was earthworm reproduction with a half maximal effective concentration (EC50) of 0.12mg/kg d.w. soil. Based on this sensitive terrestrial endpoint, the EU derived a predicted no-effect concentration (PNEC) for soil of 0.012mg/kg wet weight soil (EU 2008). We did not identify a more sensitive/lower point of departure for terrestrial toxicity endpoints in the published literature. On the basis of this PNEC, the EU concluded there was potential risk for environmental effects near TBBPA manufacturing sites, but no additional risk provided that no sewage sludge was applied to agricultural land (EU 2008).

Perfluoroalkylsulfonic and carboxylic acids in earthworms (Eisenia fetida): Accumulation and effects results from spiked soils at PFAS concentrations bracketing environmental relevance

Effects of perfluorobutanesulfonic acid (PFBS), perfluorohexanesulfonic acid (PFHxS), perfluorononanoic acid (PFNA), and perfluoroheptanoic acid (PFHpA) on earthworms (Eisenia fetida) in soils contaminated with these compounds at 0.1, 1, 10, 1,000, and 100,000 μg kg−1 dry weight, covering concentration levels found in background, biosolid–amended, and facility–surrounding soils, were investigated. Earthworms were exposed to spiked soil for 21 days. Concentrations of these compounds in earthworms after 21-d exposure ranged from below detection to 127 mg kg−1 wet weight with the rank order of PFNA > PFHxS > PFHpA > PFBS; no mortality of earthworms was observed in all treatments including controls, except PFBS at 1,000 μg kg−1 and all PFASs at 100,000 μg kg−1. The highest weight loss (29%) was observed for earthworms exposed to PFNA at 100,000 μg kg−1, which was significantly different from all other treatments except PFHpA at 100,000 μg kg−1. These results are expected to fill some data gaps in toxicity of PFASs in terrestrial environments and provide helpful information on the potential for trophic transport of PFASs from soil to higher organisms.

Toxic effects of Solanum xanthocarpum Sch &Wendle against Helicoverpa armigera (Hub.), Culex quinquefasciatus (Say.) and Eisenia fetida (Savigny, 1826).

Many commercially available agro and household chemicals are used as pesticides, repellents, and growth inhibitors against insect pests. The repeated uses of these chemicals against insect pests have caused the development of resistance in them; they also cause ill effects on nontarget organisms. The present study was aimed to evaluate the antifeedant, larvicidal, pupicidal, and biochemical effects of the solvent extracts of Solanum xanthocarpum against third instar larvae of Helicoverpa armigera. Hexane, chloroform and ethyl acetate extracts were subjected to phytochemical analysis. The results revealed the presence of terpenoids, flavonoid, and quinone. Maximum antifeedant activity of 72.30% was recorded in chloroform extract followed by hexane (69.02%) and ethyl acetate (57.40%) extracts against H. armigera. Chloroform extracts of S. xanthocarpum showed more than 60% larvicidal and pupicidal activity against H. armigera. The effective chloroform extract was fractionated with increasing polarity of solvent system (hexane, chloroform, and ethyl acetate extracts). Based on the TLC profile, nine major fractions were isolated. The fourth fraction showed higher antifeedant, larvicidal, and pupicidal activity against H. armigera. The effective fraction reduced the hemolymph and gut protein concentration in a concentration-dependent manner (r 2 0.99). The effective fraction 4 showed 100% larvicidal activity at 500ppm concentration with LC50 value of 227.95ppm. The fourth fraction did not show any toxic symptom or mortality of earthworm. Based on these results, this effective fraction could be used in the development of a pesticide formulation to control insect.

Optimization of animal manure vermicomposting based on biomass production of earthworms and higher plants

ABSTRACTThe goal of this study was to optimize the mixture of swine manure (SM) and cattle manure (CM) used in the vermicomposting process, seeking to increase the manure biodegradation rate and enhance the biomass production of both earthworms and higher plants. To achieve this goal, physico-chemical parameters were determined to assess the final compost quality after 50 days of vermicomposting. The different manure ratios used to produce the composts (C) were as follows (SM:CM, % m/m basis): C1 100:0, C2 (75:25), C3 (50:50), C4 (25:75), and C5 (0:100). In addition, the earthworm biomass and the phytoproductivity of lettuce (Lactuca sativa L.) plants grown in mixtures (1:1) of natural soil and the most viable vermicomposts were investigated. The C1 and C2 compost compositions were associated with high earthworm mortality rates. The C3 compost provided the highest mineral concentrations and C5 showed the highest lettuce yield (wet biomass). The results verify that stabilized cattle manure is an excellent substrate for the vermicomposting process and that fresh swine manure must be mixed with pre-stabilized cattle manure to ensure an optimized vermicomposting process, which must be controlled in terms of temperature and ammonia levels. It is concluded that small livestock farmers could add value to swine manure by applying the vermicomposting process, without the need for high investments and with a minimal requirement for management of the biodegradation process. These are important technical aspects to be considered when circular economy principles are applied to small farms.

Ecotoxicological effects of citrus processing waste on earthworms, Lumbricus terrestris L.

Land disposal of agro-processing wastes containing potentially toxic compounds may lead to adverse ecotoxicological effects. Compared to agrochemicals, limited data are available on the ecotoxicological effects of biowastes such as those from citrus fruit processing. The objectives of the current study were:(1) to determine the effects of varying concentrations of citrus waste extract on adult mortality, fecundity and avoidance behaviour of the earthworm species Lumbricus terrestris under laboratory conditions; and (2) to determine earthworm abundance on contaminated and uncontaminated soils under field conditions. The laboratory experiment was a short-term acute toxicity test and it showed that the concentration of citrus extract had a significant (p<0.05) negative effect on mortality, fecundity and avoidance behaviour. Exponential relationships (p<0.001) were observed between citrus extract concentration and earthworm mortality (r2=0.98–0.99) and fecundity (r2=0.98), respectively. Tests showed that citrus waste-induced avoidance behaviour in earthworms changed by 44% to 100% compared to the control. Mean effect concentration (EC50) showed that earthworm avoidance behaviour (47%) was more sensitive to citrus waste concentrations than for number of cocoons (91%) and live earthworm counts (83%). Soil dumping of citrus waste significantly increased the concentration of mineral N, available N and exchange Ca, Mg and K but significantly reduced pH relative to the uncontaminated control. The shifts in chemical properties were about 1–2 orders of magnitude for P and Ca, double for K and approximately 30–60% for pH, N and Mg. Field data showed that the contaminated site had 80%significantly lower earthworm abundance than the uncontaminated control. Overall, the current study revealed that citrus waste has adverse ecotoxicological effects, which threatens the soil biota. Further studies should focus on elucidating the exact mechanisms and exploring the pesticidal effects of citrus extract solutions, particularly on meso- and macro-invertebrates. Investigations are also required to determine the persistence and mobility of the waste in soil and how to restore contaminated soils.

Soil Contaminated with Glyphosate: Can Vermicompost Be Considered a Bioremediation Agent?

The efficiency of the addition of vermicompost in relation to the decontamination of red latosol was evaluated against acute toxicity, biomass gain and reproduction of Eisenia foetida (earthworms) incubated in the contaminated soil. The soil was spiked to different concentrations of glyphosate from 96 mg kg-1 (recommended by the manufacturer) to 10000 mg kg-1 to simulate contamination by shedding of the herbicide. To evaluate the effect of vermicompost in the soil contaminated with 10000 mg kg-1 glyphosate, 15 g of vermicompost, totaling 3%, was added to the soil. The incorporation of vermicompost to the soil inhibited earthworm mortality. However, even the dose of 96 mg kg-1 presented deleterious effects on the reproduction of E. foetida. It can be concluded that the addition of vermicompost to soil contaminated with glyphosate attenuates the deleterious action of the herbicide on E. foetida.

Trophic dynamics in a simple experimental ecosystem: Interactions among centipedes, Collembola and introduced earthworms

Invasive earthworms in North America are known to have dramatic influences on soil ecosystems, including negative effects on other soil fauna. In general, studies examining this phenomenon have focused on invasive earthworm impacts on organisms at the same or lower trophic level as the earthworms themselves (i.e., detritivores and decomposers). In contrast, there have been relatively few studies of invasive earthworm impacts on higher trophic levels or food web interactions. Invasive earthworms might alter food webs either directly as prey items, or indirectly through their profound alteration of soil physical characteristics, which might in turn alter established predator/prey interactions. In this study, we created experimental mesocosms to investigate the influence of an invasive earthworm on a native predator-prey interaction. We incubated several combinations of a widespread Asian invasive earthworm (Amynthas agrestis), a generalist centipede predator (family: Cryptopidae), and a putative microarthropod prey species (Sinella curviseta) in an experiment to determine their interactions. We hypothesized that collembolan abundance would be reduced in mesocosms containing centipedes. We further hypothesized that earthworm feeding on litter substrate in the mesocosms would reduce the complexity of the substrate, and thus increase the likelihood of centipede/collembolan encounters, with the ultimate effect of more pronounced reduction of Collembola populations in mesocosms containing both earthworms and centipedes. Unexpectedly, we found that earthworms had a negative effect on collembolan abundance early in the incubation and that centipedes did not. Collembolan populations were less variable through time in the presence of earthworms, suggesting that invasive earthworms exerted some regulatory pressure on food or habitat supply for the collembolans. Centipedes lost biomass when only Collembola were available for food, but gained biomass when incubated with earthworms. We noted a simultaneous significant decrease in earthworm biomass (mainly in the form of earthworm mortality) in experimental units that contained centipedes relative to those without centipedes. Taken together, these results suggest that this invasive earthworm may represent a novel prey resource for the centipedes, and that their presence in ecosystems could have consequences on both higher and lower trophic levels.

Effects of single and combined exposures to copper and benzotriazole on Eisenia fetida

Benzotriazole (BTR), an emerging class of environmental pollutant, is widely used in industrial applications and household dishwashing agents. Despite the reported toxicity of BTR to aquatic organisms, little is known about its effects on terrestrial invertebrates. Copper (Cu) accumulates in agricultural soils receiving urban waste products, fertilizers, fungicides, and urban sewage. In this study, two different types of bioassays (acute toxicity test and behavioral toxicity test) were performed to evaluate the toxicity of Cu and BTR, both singly and together, on the earthworm (Eisenia fetida) in artificial soil. The results of avoidance behaviour tests showed that the EC50,48 h values for Cu and BTR were 1.47 and 0.46 mmol kg−1, respectively. The results of the acute toxicity tests showed that the LC50,7 d and LC50,14 d of Cu in earthworms were 9.19 and 5.28 mmol kg−1, respectively, and the LC50,7 d and LC50,14 d of BTR were 2.43 and 1.76 mmol kg−1, respectively. Toxicity analysis demonstrated that the binary BTR and Cu mixture had predominantly antagonistic effects on the avoidance behaviour and survival of earthworms. The Cu2+ activities and mortality of earthworms decreased significantly with increasing concentrations of BTR, while the solid-liquid distribution coefficient of Cu increased. These results indicated that the presence of BTR can reduce the toxicity as well as the bioavailability of Cu in soil with both BTR and Cu.

Assessment of toxicological effects of raw and bioremediated olive mill waste in the earthworm Eisenia fetida: A biomarker approach for sustainable agriculture

The olive oil extraction process produces large amounts of olive mill waste (OMW) that can be re-used in agriculture by land spreading. OMW has a low pH, high salinity and high levels of polyphenols and is potentially dangerous for the environment. It is therefore mandatory to develop procedures able to produce OMW with lower environmental impact. The first aim of the present study was to evaluate the toxicological effects of two different typologies of OMW: raw Two-Phase Olive Mill Waste (TPOMW) and raw Olive Mill Waste Waters (OMWW), on a soil bioindicator, the earthworm Eisenia fetida, using neurotoxicity (AChE), oxidative stress (LPO, CAT) and genotoxicity (comet assay) biomarkers. The second aim was to test the efficacy of a composting/bioaugmentation process by investigating the toxicological effects of the bioremediated OMW. E. fetida was exposed for 72h to increasing concentrations (12.5, 25, 50%) of raw and bioremediated TPOMW and OMWW in an artificial soil (50% potting soil+50% quartz sand). Raw OMW caused earthworm mortality at high doses and measurable biochemical and cellular effects at lower doses. The main cause of these effects is probably the high level of polyphenols present in the OMW. Neurotoxic effects, induction of oxidative stress and genotoxic effects were highlighted. The most evident toxicological effects were produced by the TPMW. The evaluation of the bioremediation process efficacy revealed that a high decrease in acidity and polyphenol content corresponds to a decrease of toxicological effects. This study contributed to assess the environmental sustainability of the bioremediated OMWs, to be used as fertilizers in agriculture.

Effects of polystyrene microplastics on the fitness of earthworms in an agricultural soil

Microplastics (MPs) pollution is widespread in the environment, while the effects of MPs on the soil organisms are poorly understood. In this study, we investigated the fitness of earthworms (E. Foetida) exposed to MPs (Polystyrene, 58 μm) in soils at the concentrations of 0, 0.25, 0.5, 1 and 2% (w/w). The results showed that MPs had little effects on the fitness of earthworms under low exposure concentrations (≤ 0.5 % (w/w)), while MPs exposure with high concentrations (i.e., 1% and 2%) significantly inhibited the growth and increased the mortality of earthworms. The results indicated that the MPs pollution in soils have an adverse effect on the fitness of soil organisms, and implied the ecological risk of MPs in terrestrial ecosystems.

English

Earthworms might be limited in their activities on soil by pesticides used at important rates in agriculture and human pathogenic micro-organisms introduced in soil by excreta. This study using a modified toxicity filter paper contact test from Organisation for Economic Co-operation and Development (OECD), aimed at assessing the toxicity of six pesticides formulations and six micro-organisms on the earthworm Eisenia fetida. The study performed over 7 months at the laboratory QAlEA (University of Caen Normandie, France), analysed the mortality every 24 h for 96 h and at 96 h of E. fetida when exposing to pesticides and microbial suspensions. The statistical test used is the Student’s t-test at the significant level of 0.05. No mortality of earthworms was observed when testing these pesticides at their recommended agricultural concentrations. Toxicity order from the highest to the lowest, based on LC50, was Capiscol, Stratos Ultra Jardin, Polyvalent, Roundup GT Plus, Polyflor and KB Limace. Among tested micro-organisms, only Enterobacter cloacae (culture broth) and Listeria monocytogenes (culture broth and supernatant) generate mortalities of E. fetida. Finally, all these tested pesticides do not lead to E. fetida mortality if they are used at their recommended agricultural concentrations. Earthworms species E. fetida are also stressed by some micro-organisms. Furthermore, the filter paper contact test OECD might be used as a tool to evaluate the response of E. fetida to abiotic and biotic stresses. Key words: Stress, toxicity, pesticides, micro-organisms.

HERBICIDE GLYPHOSATE IMPACT TO EARTHWORM (E. FETIDA) / HERBICIDO GLIFOSATO POVEIKIO KOMPOSTINIAM SLIEKUI (E. FETIDA L.) TYRIMAI IR VERTINIMAS

Glyphosate is a broad spectrum weed resistant herbicide. Glyphosate may pose negative impact on land ecosystems because of wide broad usage and hydrofilic characteristic. The aim of this study was to investigate negative effects of glyphosate on soil invertebrate organisms (earthworm Eisenia fetida). The duration of experiment was 8 weeks. The range of the test concentrations of glyphosate were: 0,1, 1, 5, 10, 20 mg/kg. To investigate the glyphosate impact on earthworm Eisenia fetida the following endpoints were measured: survival, reproduction and weight. The exposure to 20 mg/kg glyphosate has led to the 100% mortality of earthworms. Glyphosate has led to decreased E. fetida reproduction, the cocoons were observed only in the lowest concentration (0,1 mg/kg). In general: long-term glyphosate toxicity to earthworms (E. fetida) may be significant. Glifosatas yra herbicidas, plačiai naudojamas piktžolėms naikinti. Dėl masinio ir netinkamo naudojimo bei didelio tirpumo vandenyje glifosatas turi įtakos sausumos ekosistemoms. Eksperimento tikslas – įvertinti skirtingų glifosato koncentracijų poveikį žieduotosioms kirmėlėms (kompostiniam sliekui Eisenia fetida L.). Tyrimas buvo vykdomas 8 savaites. Eksperimento metu buvo naudotos 0,1, 1, 5, 10, 20 mg/kg glifosato koncentracijos dirvožemyje. Glifosato poveikio kompostiniams sliekams E. Fetida įvertinti buvo tirti augimo, mirtingumo ir reprodukcijos rodikliai. Eksperimento metu nustatyta, jog didelės glifosato koncentracijos letaliai veikė kompostinį slieką. Esant didžiausiai 20 mg/kg koncentracijai, sliekų mirtingumas jau pirmąją savaitę buvo 100 %. Didėjanti glifosato koncentracija mažino kompostinio slieko E. fetida svorio prieaugius bei neigiamai veikė sliekų reprodukciją, kokonai užfiksuoti tik esant mažiausiai koncentracijai. Eksperimento pabaigoje nustatyta tendencija – kuo ilgesnis glifosato ekspozicijos laikas, tuo didesnė žala daroma dirvožemio bestuburiams (Eisenia fetida).

The effects of soil compaction mitigation on below-ground fauna: How earthworms respond to mechanical loosening and power harrow cultivation

Soils are one of the most biologically diverse habitats within the terrestrial ecosystem. Although soils are vital to the provision of important ecosystem services, their direct protection and sustainable management are often lacking within conservation policy. Many grassland soils have undergone considerable management intensification and are subject to degradation pressures. Soil compaction is an important form of soil degradation that can reduce soil productivity and crop yields, although the impacts can be reversed through natural processes and mitigated through management interventions. While commonly used, substantial knowledge gaps exist regarding the impact of soil compaction mitigation techniques on key soil macrofauna; many of these organisms are essential to soil function. A complete split-plot design was used to investigate the impacts of mechanical loosening (subsurface soil disturbance using tines or radial blades without significant soil mixing or inversion) and power harrow cultivation (shearing and mixing of soil to prepare a seedbed for the establishment of a deep-rooting forb and legume mix) on the abundance and biomass of earthworms up to two years post-treatment. Mechanical loosening was undertaken at two depths, c. 20 cm and c. 35 cm as two separate treatments. There was a negative effect of mechanical loosening at both depths on the abundance and biomass of anecic earthworms, lasting up to two years post-treatment. There was no significant effect of power harrow cultivation on the abundance or biomass of earthworms. These negative effects are consistent with other studies that have shown mechanical loosening to be a source of earthworm mortality. Although these findings resulted from a single episode of power harrow cultivation and mechanical loosening at a single site, the results indicate that the mechanical loosening of grassland soil can have a negative impact on important soil macrofauna and should possibly only be undertaken when the soil is in the most severely degraded conditions. Further work is needed to determine whether the negative impact of mechanical loosening is common to multiple sites and soil types and to link the reduction in earthworm number and biomass to future soil function.

Trophic transfer of silver nanoparticles from earthworms disrupts the locomotion of springtails (Collembola)

Understanding how nanomaterials are transferred through food chains and evaluating their resulting toxicity is important. However, limited research has been conducted on the toxic consequences of trophically transferred nanomaterials in terrestrial ecosystems. In this study, we documented the adverse effects of trophically transferred silver nanoparticles (AgNPs) in a soil–earthworm (Eisenia andrei)–Collembola (Lobella sokamensis) food chain. We exposed E. andrei to soil with AgNPs at concentrations of 50, 200, and 500μg AgNPs/g soil dry weight and assessed their survival after 7days. Trophic-transfer containers were then prepared and E. andrei that survived the 7days test period were washed, killed in boiling water, and added to the containers with L. sokamensis. We noted negligible effects and low bioaccumulation at the lowest AgNP concentration (50μg AgNPs/g soil dry weight) in earthworms and the L. sokamensis that fed on them. The highest concentration of AgNPs (500μg AgNPs/g soil dry weight) resulted in juvenile earthworm mortality and increased transfer of AgNPs to Collembola, which subsequently inhibited their locomotion. To our knowledge, this is the first study to document the trophic transfer and adverse effects of AgNPs in a soil–earthworm–Collembola food chain, a common prey–decomposer interaction in soil ecosystems.

Efficiency of Chemical Amendments for Reducing Ecotoxicity in Heavy Metal Polluted Agricultural Fields

This study was conducted to evaluate effect of chemical amendments on reducing bioavailable fraction of heavy metals in soil along with ecotoxicological effect on earthworms, Eisenia fetida. Three different chemical amendments, lime (L), steel slag (SS), and acid mine drainage sludge (AMDS), were applied with varied application ratio (1, 3, 5%). Heavy metal contaminated soil was mixed with chemical amedments and earthworms, Eisenia fetida, were cultivated for 28 days. Bioavailable fraction of heavy metals (Cd, Cu, Pb, and Zn) extracted with 0.1N HCl was monitored and also, mortality, growth, and metal concentration in earthworm were assessed. Result showed that all three amendments had high efficiency to reduce bioavailable fraction of heavy metals in soil. In particular, lime showed the highest reduction rate of Cu (63.9-87.7%), Pb (7.90-24.65%), and Zn (40.83-77.60%) among three amendments. No mortality of earthworm was observed during experimental period except 3% and 5% AMDS treatment indicating that application of chemical amendments is safe in terms of ecotoxicological aspect. However, no positive correlation was observed between reduction of bioavaialble fraction of heavy metals in soil and earthworms. Overall, application of chemical amendments in agricultural field can be adapted for reducing bioavailable fraction of heavy metals and detoxification in soil.

Physiological and genotoxic responses of the earthworm Aporrectodea caliginosa exposed to sublethal concentrations of AgNPs

The purpose of the current study was to measure the ecotoxicity of silver nanoparticles (AgNPs) on Aporrectodea caliginosa earthworm. No adult earthworm mortality was observed at any treatment during the sub-chronic exposure period (28d). Biomass and cellulase levels reduced in a concentration-dependent manner in the exposed earthworms compared to those of the control. The hatched cocoons from the contaminated substrates were significantly (p<0.05) fewer than that of the control substrate. This finding provided further support for the conclusion that AgNPs may affect cocoon hatchability. Cocoon hatchability could therefore be a more reliable endpoint at a specific concentration than cocoon production. A significant increase in DNA damage was revealed in the earthworms treated with AgNPs compared to the untreated ones. The results denoted the effectiveness of measuring cellulase activity, biomass, reproduction and DNA damage and reinforced the application of the present methods in nanoparticles pollution biomonitoring studies.

Development of a Metals Toxicity Protocol for Biosolids

Sixty percent of all wastewater treatment biosolids are recycled, compared to 30% in 1990. Environmental biosolids management systems are now commonly implemented for municipalities. The promotion of beneficial use of biosolids has transformed our historic view of processed wastewater treatment residuals. Instead of wastes requiring disposal, we now view biosolids as valuable manufactured products. Land application of biosolids has proven to be beneficial because organic matter and nutrients can be used effectively for enhancement of agricultural crop production. There is concern, however, about the potential for degradation of soil quality. Although thorough investigations of potential risk from biosolids have generally indicated that land application does not threaten human or ecosystem health, questions continue to arise concerning the safety of biosolids recycling. This project was initiated to evaluate the toxicity resulting from the amendment of soils with biosolids from municipal wastewater treatment. Toxicity was evaluated using standard tests including earthworm mortality, growth, and reproduction; seedling germination and root elongation; microbial respiration; and nematode mortality/reproduction. In addition, chemical lability tests for metals were employed including water soluble, exchangeable, and metals extractable by the physiologically based extraction test (PBET). This title belongs to WERF Research Report Series ISBN: 9781843396895 (eBook)

Ecotoxicological evaluation of swine manure disposal on tropical soils in Brazil

Swine production in Brazil results in a great volume of manure that normally is disposed of as agricultural fertilizer. However, this form of soil disposal, generally on small farms, causes the accumulation of large amounts of manure and this results in contaminated soil and water tables. To evaluate the effects of increasing concentrations of swine manure on earthworms, several ecotoxicological tests were performed using Eisenia andrei as test organism in different tropical soils, classified respectively as Ultisol, Oxisol, and Entisol, as well as Tropical Artificial Soil (TAS). The survival, reproduction and behavior of the earthworms were evaluated in experiments using a completely randomized design, with five replications. In the Ultisol, Oxisol and TAS the swine manure showed no lethality, but in the Entisol it caused earthworm mortality (LOEC=45m3ha−1). In the Entisol, the waste reduced the reproductive rate and caused avoidance behavior in E. andrei (LOEC=30m3ha−1) even in lower concentrations. The Entisol is extremely sandy, with low cation exchange capacity (CEC), and this may be the reason for the higher toxicity on soil fauna, with the soil not being able to hold large amounts of pollutants (e.g. toxic metals), but leaving them in bioavailable forms. These results should be a warning of the necessity to consider soil parameters (e.g. texture and CEC) when evaluating soil contamination by means of ecotoxicological assays, as there still are no standards for natural soils in tropical regions. E. andrei earthworms act as indicators for a soil to support disposal of swine manure without generating harm to agriculture and ecosystems.

Sublethal effects of epoxiconazole on the earthworm Aporrectodea icterica.

Earthworms play a key role in agroecosystem soil processes. This study aims to assess the effects of different doses of a commercial formulation of epoxiconazole (Opus®), a persistent and widely used fungicide, on the earthworm Aporrectodea icterica. A laboratory study was conducted in a natural soil in order to measure effects of Opus® on earthworm mortality, uptake, weight gain, enzymatic activities (catalase and glutathione-S-transferase), and energy resources (lipids and glycogens). The estimated LC50 was 45.5 mg kg(-1), or 268 times the recommended dose. Weight gains were 28, 19, and 13% of the initial weight after 28 days of exposure in the control and D1 and D10 (1 and 10 times the recommended dose) treatments, respectively. No difference was observed for catalase activity between the three treatments, at 7, 14, or 28 days. The glutathion-S-transferase (GST) activity was two times as high in D1 as in D0 at 14 days. At 28 days, glycogen concentration was lower in D10 than in the D1 treatment. This study highlighted moderate sublethal effects of the commercial formulation Opus® for earthworms. Considering that these effects were observed on a species found in cultivated fields, even at recommended rates, much more attention should be paid to this pesticide.