Feeding inhibition in the soil collembolan Folsomia candida as an endpoint for the estimation of organic waste ecotoxicity

Despite the increasing quantities of organic wastes that are being reused in soils, there are few studies that focus on the selection of bioassays for the ecotoxicological risk assessment of organic wastes to soils. In the present study, differences in feeding inhibition in the soil collembolan Folsomia candida were evaluated as an ecotoxicological endpoint for the assessment of risk to soils amended with polluted organic wastes. Seven organic wastes (dewatered sewage sludges, thermally dried sewage sludges, composted sewage sludges, and a thermally dried pig slurry) were tested. These wastes had different origins, treatments, and pollutant burdens, and were selected as a representative sample of the wide variety of wastes currently generated. A clear dose response was observed for this parameter, with an increase in percentage of individual feeding inhibition with increased doses of organic wastes. More significantly, feeding inhibition correlated highly with mortality and reproduction inhibition in the different wastes. Composted sludges displayed the lowest toxicity, followed by thermally dried sludge and dewatered sludge. Thermally dried pig slurry showed the highest toxicity for feeding, with lower median effective concentration (EC50) values than the lowest dose tested. Among waste physicochemical parameters and pollutants, low organic matter stability appeared to be the main predictor of potential adverse effects on soil fauna, because it correlated significantly with feeding inhibition and mortality. Furthermore, feeding inhibition tests were run over a short exposure time (less than 7 d), which, together with the results obtained, makes this bioassay a good screening tool for organic waste toxicity

Use of terrestrial field studies in the derivation of bioaccumulation potential of chemicals

Field-based studies are an essential component of research addressing the behavior of organic chemicals, and a unique line of evidence that can be used to assess bioaccumulation potential in chemical registration programs and aid in development of associated laboratory and modeling efforts. To aid scientific and regulatory discourse on the application of terrestrial field data in this manner, this article provides practical recommendations regarding the generation and interpretation of terrestrial field data. Currently, biota-to-soil-accumulation factors (BSAFs), biomagnification factors (BMFs), and bioaccumulation factors (BAFs) are the most suitable bioaccumulation metrics that are applicable to bioaccumulation assessment evaluations and able to be generated from terrestrial field studies with relatively low uncertainty. Biomagnification factors calculated from field-collected samples of terrestrial carnivores and their prey appear to be particularly robust indicators of bioaccumulation potential. The use of stable isotope ratios for quantification of trophic relationships in terrestrial ecosystems needs to be further developed to resolve uncertainties associated with the calculation of terrestrial trophic magnification factors (TMFs). Sampling efforts for terrestrial field studies should strive for efficiency, and advice on optimization of study sample sizes, practical considerations for obtaining samples, selection of tissues for analysis, and data interpretation is provided. Although there is still much to be learned regarding terrestrial bioaccumulation, these recommendations provide some initial guidance to the present application of terrestrial field data as a line of evidence in the assessment of chemical bioaccumulation potential and a resource to inform laboratory and modeling efforts

Integrated evaluation of the ecotoxicological risk of using sewage sludges in agriculture and in soil restoration

Tese de doutoramento em Biologia, especialidade de Ecologia, apresentada à Fac. de Ciências e Tecnologia de CoimbraA análise química exigida por lei para regulamentar o uso de lamas residuais na agricultura é claramente insuficiente para avaliar o risco potencial da utilização deste tipo de resíduos em solo, dado que nem o efeito de contaminantes não incluídos na análise química nem os efeitos que ocorrem como resultado de interacções entre compostos químicos são tidos em linha de conta. Por essa razão a necessidade em complementar as análises químicas com a realização de uma bateria de bioensaios para uma adequada caracterização ecotoxicológica deste tipo de resíduos é amplamente reconhecida. Dos contaminantes frequentemente encontrados em lamas residuais os metais constituem um risco potencial para os organismos edáficos. O grau de contaminação no solo é geralmente avaliado pela concentração total de metais; no entanto, o risco real é determinado pela fracção de metais que está biologicamente disponível para os organismos. Essa fracção está relacionada com a força da ligação do metal à matriz e pode variar ao longo do tempo devido a processos naturais ou antropogénicos. Além de factores abióticos, também processos biológicos, como a actividade das minhocas, são capazes de induzir mudanças na disponibilidade de metais, influenciando a sua distribuição no solo. Além da contaminação por metais, a toxicidade deste tipo de resíduos também pode estar relacionada com a presença de outros produtos químicos perigosos gerados por actividades humanas, como é o caso dos hidrocarbonetos aromáticos policíclicos (PAHs). Tem sido demonstrada a capacidade das minhocas para promover a biodegradação de PAHs no solo. No entanto, até agora, o mecanismo através do qual as minhocas exercem essa influência ainda é desconhecido. Neste contexto, os principais objectivos deste trabalho foram: i) contribuir para a discussão e definição de estratégias adequadas para a caracterização ecotoxicológica de resíduos; ii) avaliar as alterações na disponibilidade de metais numa lama contaminada com metais ao longo do tempo e o papel de alguns factores como a matriz de contaminação e a actividade de minhocas nessas alterações; e iii) avaliar a influência da actividade das minhocas em processos microbianos do solo que possam estar de alguma forma relacionados com o aumento da biodegradação de PAHs. No Capítulo 2, foi testada uma bateria de ensaios ecotoxicológicos com plantas (Brassica rapa e Avena sativa) e invertebrados do solo (Eisenia andrei e Folsomia candida) para a caracterização ecotoxicológica de três lamas provenientes de fontes distintas (ETAR urbana e de indústria de processamento de azeite e galvanoplastia), fornecendo informações sobre os seus potenciais riscos e "níveis seguros" de aplicação. Os resultados mostraram que a avaliação ecotoxicológica de resíduos pode ser usada como uma ferramenta de controlo ambiental para a utilização de lamas na agricultura e apoiam a adopção de uma abordagem em diferentes etapas (“tiered approach”) para este efeito. No Capítulo 3 foi avaliada a adequabilidade do uso de ensaios de fuga com colêmbolos em etapas preliminares da avaliação de risco (”lower tier”), e a sua capacidade para despoletar ensaios de reprodução numa etapa posterior (”higher tiers”) nas mesmas misturas de lama e solo utilizadas no Capítulo 2, após 0, 4 e 12 semanas de incubação. Os resultados comprovaram a eficiência destes ensaios de fuga na caracterização ecotoxicológica preliminar de lamas perigosas e ainda na avaliação das alterações da toxicidade ao longo do tempo. No Capítulo 4, foi avaliada a toxicidade de uma mistura de crómio (Cr), cobre (Cu), níquel (Ni) e zinco (Zn) aplicada no solo directamente ou através de uma matriz orgânica por intermédio de ensaios de reprodução com minhocas (E. andrei) e colêmbolos (F. candida). Os resultados demonstraram que uma avaliação comparativa deste tipo fornece informação útil sobre o efeito da lama (contaminantes) e da matriz na toxicidade dos metais. No Capítulo 5, foram avaliadas as alterações na disponibilidade de metais a curto prazo, quando aplicados directamente no solo (solos com solução de metais) ou através de uma matriz orgânica (solos com lama) através de um ensaio de laboratório em microcosmos ao longo de 12 semanas. Os resultados demonstraram que a matriz lama contribuiu, de um modo geral, para reduzir a mobilidade dos metais no solo. Nos solos contaminados com solução de metais a disponibilidade de metais diminuiu independentemente da concentração e nos solos contaminados com lama a disponibilidade de metais manteve-se estável ao longo do tempo em todas as doses. No Capítulo 6 foi realizada uma experiência complementar à apresentada no Capítulo 5, onde foram adicionadas minhocas da espécie Dendrobaena veneta aos microcosmos para avaliar a influência da actividade das minhocas na disponibilidade dos metais a curto prazo. Os resultados mostraram que a actividade das minhocas não alterou a disponibilidade dos metais em nenhum tratamento ao longo do tempo, contudo interferiu no conteúdo em metais dos percolados. As concentrações de Ni, Cu e Cr em D. veneta foram maiores nos tratamentos com concentrações de metais mais elevadas; já a concentração interna de Zn não apresentou esta tendência sendo regulada pelas minhocas. Modelos retirados da literatura não foram capazes de prever os níveis de metais medidos em D. veneta. No Capítulo 7, foi realizado um ensaio de mesocosmos em campo ao longo de um ano para avaliar as alterações na disponibilidade de metais a longo prazo, comparando também o efeito da matriz (solos contaminados com lama vs solução de metais) e a influência da actividade das minhocas (numa densidade realista de 500 minhocas D. veneta por m2). Os resultados não revelaram alterações na concentração de metais totais mas demonstraram uma diminuição na extractabilidade do Ni ao longo do tempo. A actividade das minhocas não interferiu na concentração de metais ao longo do tempo. As concentrações de Cr e Ni nas minhocas foram dependentes das respectivas concentrações no solo em alguns tratamentos e as concentrações internas de Cu e Zn foram reguladas pelas minhocas. Os modelos testados estimaram melhor as concentrações de Cu, Ni e Cr nas minhocas, masnão as de Zn. No Capítulo 8, foi realizada uma experiência de laboratório em microcosmos para avaliar a influência da colonização de minhocas na actividade microbiana relacionada com a biodegradação de PAHs no solo. Foram efectuadas amostragens destrutivas de colunas de solo com um estrato superficial de sedimento dragado, contaminado predominantemente com PAHs, ao longo de 18 semanas, para medir parâmetros químicos e microbianos. Os resultados sugerem que não há relação directa entre as alterações da actividade microbiana facilitada pela actividade das minhocas e o aumento da degradação dos PAHs no solo. No entanto, o papel das alterações na estrutura da comunidade microbiana do solo, induzida pelas minhocas, na remoção de PAHs necessita de mais investigação.Chemical analysis required by law to regulate sewage sludge use in agriculture is clearly insufficient to indicate potential risk of sludge amendments in soil because neither the effect of contaminants not screened in chemical analysis nor the effects that occur as a result of multi-chemical interactions are taken into account. Because of that, the need for a test battery of ecotoxicological assays for a proper ecotoxicological characterization of sludges as a complement of chemical analysis is widely recognized. The high level of metals often found in sewage sludges constitutes a potential risk for soil organisms. The degree of soil contamination is generally evaluated by total metal concentrations; however, the real risk of metals is determined by the fraction that is biologically available for the organisms. The available fraction is highly related with the strength of metal binding by the matrix and may change over time due to natural or anthropogenic processes. Besides abiotic factors also biotic processes, like earthworm activity, may induce changes in metal availability by influencing metal partitioning in soil. Besides metal contamination, the toxicity of wastes may also be related to the presence of other hazardous chemicals generated by human activities, including polycyclic aromatic hydrocarbons (PAHs). The ability of earthworms to promote biodegradation of PAHs in soil has been reported. However, until date, the mechanism through which the earthworms exert such influence is still unknown. Under this context, the main objectives of this thesis were i) to discuss and give a contribute to the definition of suitable strategies for ecotoxicological waste characterization; ii) to evaluate the changes in metal availability of a metalcontaminated sludge over time and the role of factors like soil matrix and earthworm activity in those changes; and iii) to evaluate the influence of earthworm activity on soil microbial processes that may be related with increasing PAH biodegradation. In Chapter 2 a battery of ecotoxicological assays using plant (Brassica rapa and Avena sativa) and soil invertebrate species (Eisenia andrei and Folsomia candida) is proposed for the ecotoxicological characterization of three sludges from distinct sources (urban, olive-processing, and electroplating industries), providing information on their potential hazard and identifying “safe” application levels. Results showed that the ecotoxicological evaluation of wastes can be used as an environmental safety control of sludge use in agriculture and that a tiered approach may be adopted for this purpose. The use of Collembola avoidance tests in a screening level (low tier) acting as a trigger for collembolan reproduction tests (high tier) was assessed in Chapter 3 for the same soil-sludge mixtures used in Chapter 2 after 0, 4, and 12 weeks of incubation. Results demonstrated the ability of collembolan avoidance tests to assess changes in sewage sludge toxicity over time and its potential for hazardous sludge characterization at low tier levels. In Chapter 4, the toxicity of a mixture of chromium (Cr), copper (Cu), nickel (Ni), and zinc (Zn) applied to soil directly or via an organic matrix was evaluated through earthworm (E. andrei) and Collembola (F. candida) reproduction tests. Results demonstrated that this comparative approach provides useful information on the effect of the sludge matrix on the toxicity of metals. In Chapter 5 the short-term changes in metal availability when applied to soil directly (metal-spiked soils) or via an organic matrix (sludge-amended soils) were evaluated in a microcosm laboratory experiment over 12 weeks. Results demonstrated that the sludge matrix generally contributed to reduce the mobility of metals in soil. In spiked treatments, metal availability decreased independently of test concentration and in sludge-amended soils the availability of metals remained stable over time in all treatments. In Chapter 6 a complementary experiment was performed with the inclusion of earthworms (Dendrobaena veneta) to the microcosms to assess the influence of earthworm activity on metal availability on a short-term basis. Results showed that earthworm activity did not affect metal availability of any treatment over time, but their burrowing activities did interfere with the metal content of percolates. Nickel, Cu and Cr concentrations in D. veneta were higher at the highest treatment levels, whereas Zn internal concentration was regulated. Models taken from the literature were not able to predict the metal levels measured in D. veneta. In Chapter 7, an outdoors mesocosm experiment was conducted over one year to evaluate long-term changes of metal availability, also comparing the effect of the matrix (sludge amended vs spiked soils) and the activity of earthworms (a realistic density of 500 D. veneta per m2). Results showed no changes in total metal concentrations and a decrease only in Ni extractability over time. Earthworm activity did not affect metal concentrations over time. Earthworm Cr and Ni concentrations were dependent on soil metal concentrations in some treatments and internal Cu and Zn concentrations were regulated by D. veneta. Models taken from the literature best estimated Cu, Ni, and Cr but not Zn concentrations in the earthworms. In Chapter 8, a microcosm laboratory experiment was conducted to evaluate the influence of earthworm colonization and activity in facilitating microbial processes related to the biodegradation of PAHs in soil. Columns containing a layer of dredge sediment contaminated predominantly with PAHs on top of uncontaminated natural soil without and with low and high E. andrei densities were destructively sampled over 18 weeks for measurement of chemical and microbial parameters. Results suggest no direct relationship between changes in the microbial activity mediated by earthworms and the increased PAH degradation. However, the role in PAH decrease of shifts in soil microbial community structure induced by earthworms needs further investigation.O trabalho científico desta dissertação foi financiado pela Fundação para a Ciência e a Tecnologia sob a forma de bolsa de investigação (referência: SFRH /BD / 29437 / 2006) co-financiada pelo Fundo Social Europeu no âmbito do Programa Operacional Potencial Humano do Quadro de Referência Estratégica Naciona

The Recolonization Concentration Concept: Using Avoidance Assays with Soil Organisms to Predict the Recolonization Potential of Contaminated Sites

In this study the recolonization concentration concept for soil organisms is presented and validated. This concept is based on the empirically deduced avoidance-recolonization hypothesis, which shows a negative correlation between avoidance (ACx) and recolonization (RCx) (ACx = RC100-x) responses. The concept was validated in a two-step approach composed by (i) individual placement tests, to demonstrate the non-influence of individual placement in a dual chamber avoidance test and (ii) small scale gradient tests to demonstrate that the number of colonizers reaching a soil patch with a certain concentration is independent on their previous exposure to lower concentrations. Overall, data show that avoidance data can be used, when framed under the recolonization concentration concept, to evaluate the recolonization potential of contaminated sites. The recolonization concept is an important theoretical concept that when coupled with spatial modelling tools could be used to tackle the spatial and temporal recovery dynamics of contaminated soil

Effects of essential oils from Eucalyptus globulus leaves on soil organisms involved in leaf degradation

The replacement of native Portuguese forests by Eucalyptus globulus is often associated with deleterious effects on terrestrial and aquatic communities. Several studies have suggested that such a phenomenon is linked with the leaf essential oils released into the environment during the Eucalyptus leaf degradation process. However, to date, the way these compounds affect leaf degradation in terrestrial systems i.e. by direct toxic effects to soil invertebrates or indirectly by affecting food of soil fauna, is still unknown. In order to explore this question, the effect of essential oils extracted from E. globulus leaves on terrestrial systems was investigated. Fungal growth tests with species known as leaf colonizers (Mucor hiemalis, Alternaria alternata, Penicillium sp., Penicillium glabrum and Fusarium roseum) were performed to evaluate the antifungal effect of essential oils. In addition, a reproduction test with the collembolans Folsomia candida was done using a gradient of eucalyptus essential oils in artificial soil. The influence of essential oils on feeding behaviour of F. candida and the isopods Porcellio dilatatus was also investigated through food avoidance and consumption tests. Eucalyptus essential oils were lethal at concentrations between 2.5-20 µL/mL and inhibited growth of all fungal species between 1.25-5 µL/mL. The collembolan reproduction EC50 value was 35.0 (28.6-41.2) mg/kg and both collembola and isopods preferred leaves without oils. Results suggested that the effect of essential oils in leaf processing is related to direct toxic effects on fungi and soil fauna and to indirect effects on the quality and availability of food to soil invertebrates

Feeding inhibition in the soil collembolan Folsomia candida as an endpoint for the estimation of organic waste ecotoxicity

Despite the increasing quantities of organic wastes that are being reused in soils, there are few studies that focus on the selection of bioassays for the ecotoxicological risk assessment of organic wastes to soils. In the present study, differences in feeding inhibition in the soil collembolan Folsomia candida were evaluated as an ecotoxicological endpoint for the assessment of risk to soils amended with polluted organic wastes. Seven organic wastes (dewatered sewage sludges, thermally dried sewage sludges, composted sewage sludges, and a thermally dried pig slurry) were tested. These wastes had different origins, treatments, and pollutant burdens, and were selected as a representative sample of the wide variety of wastes currently generated. A clear dose response was observed for this parameter, with an increase in percentage of individual feeding inhibition with increased doses of organic wastes. More significantly, feeding inhibition correlated highly with mortality and reproduction inhibition in the different wastes. Composted sludges displayed the lowest toxicity, followed by thermally dried sludge and dewatered sludge. Thermally dried pig slurry showed the highest toxicity for feeding, with lower median effective concentration (EC50) values than the lowest dose tested. Among waste physicochemical parameters and pollutants, low organic matter stability appeared to be the main predictor of potential adverse effects on soil fauna, because it correlated significantly with feeding inhibition and mortality. Furthermore, feeding inhibition tests were run over a short exposure time (less than 7 d), which, together with the results obtained, makes this bioassay a good screening tool for organic waste toxicity

Organic wastes as soil amendments - Effects assessment towards soil invertebrates

Using organic wastes, as soil amendments, is an important alternative to landfilling with benefits to soil structure, water retention, soil nutrient and organic matter concentrations. However, this practice should be monitored for its environmental risk due to the frequent presence, of noxious substances to soil organisms. To evaluate the potential of eight organic wastes with different origins, as soil amendments, reproduction tests with four soil invertebrate species (Folsomia candida, Enchytraeus crypticus, Hypoaspis aculeifer, Eisenia feticta) were performed using gradients of soil waste Mixtures. Results obtained demonstrated that contaminant concentrations required by current legislation might not be a protective measure for the soil ecosystem, as they do not properly translate the potential toxicity of wastes to soil invertebrates. Some wastes with contaminant loadings below thresholds showed higher toxicity than wastes with contaminants concentrations above legal limits. Also, test organism reproduction was differently sensitive to the selected wastes, which highlights the need to account for different organism sensitivities and routes of exposure when evaluating the toxicity of such complex mixtures. Finally this study shows that when combining chemical and ecotoxicological data, it is possible to postulate on potential sources of toxicity, contributing to better waste management practices and safer soil organic amendment products. (C) 2017 Elsevier B.V. All rights reserved.Fundacao para a Ciencia e a Tecnologia (FCT) [PTDC/AAC - AMB/119273/2010][SFRH/BPD/110943/2015][SFRH/BPD/84140/2012

Ecotoxicological characterization of a tropical soil after diazinon spraying

IRETThe impact of diazinon spraying in an agricultural tropical soil through the evaluation of both the habitat and retention functions of the soil system was never reported. To fill this gap, five times the recommended dose of a commercial diazinon formulation was sprayed in an agricultural area of Costa Rica, and dilution gradients of the sprayed soil were prepared in the laboratory. Avoidance and reproduction tests with soil organisms (Eisenia andrei, Enchytraeus crypticus and Folsomia candida) to evaluate losses in terrestrial habitat function, and growth and reproduction tests with aquatic organisms (Chlorella vulgaris and Daphnia magna, respectively) to evaluate the retention function of soil were performed. Results demonstrated that regarding habitat function, F. candida reproduction was the most sensitive endpoint (EC50 = 0.288 mg a.i./kg), followed by avoidance behaviour of E. andrei (EC20 = 1.75 mg a.i./kg). F. candida avoidance and the reproduction of E. andrei and E. crypticus were not affected by diazinon. The toxicity tests with aquatic organisms showed that the soil retention function was insufficient to prevent effects of diazinon either on microalgae growth (EC50 B ≤.742 mg/L and EC20 B ≤.223 mg/L) and on the reproduction of the cladoceran (EC50 B ≤.00771 mg/L and EC 20 B ≤.00646 mg/L). Results suggested that diazinon exerted toxic effects even at the dilution corresponding to the recommended dose, fact which makes its misuse an issue of environmental concern. Furthermore, the present study highlighted the importance and complementary nature of the assessment of both habitat and retention functions to an ecological risk assessment in tropical systems.Nunca se informó sobre el impacto de la fumigación con diazinón en un suelo agrícola tropical a través de la evaluación tanto del hábitat como de las funciones de retención del sistema del suelo. Para llenar este vacío, se roció cinco veces la dosis recomendada de una formulación comercial de diazinón en un área agrícola de Costa Rica y se prepararon gradientes de dilución del suelo rociado en el laboratorio. Se realizaron pruebas de evitación y reproducción con organismos del suelo (Eisenia andrei, Enchytraeus crypticus y Folsomia candida) para evaluar pérdidas en la función del hábitat terrestre, y pruebas de crecimiento y reproducción con organismos acuáticos (Chlorella vulgaris y Daphnia magna, respectivamente) para evaluar la función de retención del suelo. realizado. Los resultados demostraron que con respecto a la función del hábitat, la reproducción de F. candida fue el criterio de valoración más sensible (CE50 = 0,288 mg a.i./kg), seguido del comportamiento de evitación de E. andrei (CE20 = 1,75 mg a.i./kg). F. La evitación de cándida y la reproducción de E. andrei y E. crypticus no se vieron afectadas por el diazinón. Las pruebas de toxicidad con organismos acuáticos mostraron que la función de retención del suelo era insuficiente para prevenir los efectos del diazinón en el crecimiento de microalgas (EC50 B ≤.742 mg / L y EC20 B ≤.223 mg / L) y en la reproducción del cladocerano ( EC50 B ≤.00771 mg / L y EC 20 B ≤.00646 mg / L). Los resultados sugirieron que el diazinón ejercía efectos tóxicos incluso a la dilución correspondiente a la dosis recomendada, hecho que hace que su mal uso sea un problema ambiental. Además, el presente estudio destacó la importancia y la naturaleza complementaria de la evaluación de las funciones de hábitat y retención a una evaluación de riesgo ecológico en los sistemas tropicales.O impacto da pulverização de diazinon em um solo agrícola tropical por meio da avaliação do habitat e das funções de retenção do sistema de solo nunca foi relatado. Para preencher esta lacuna, cinco vezes a dose recomendada de uma formulação comercial de diazinon foi pulverizada em uma área agrícola da Costa Rica, e gradientes de diluição do solo pulverizado foram preparados em laboratório. Os testes de evitação e reprodução com organismos do solo (Eisenia andrei, Enchytraeus crypticus e Folsomia candida) para avaliar as perdas na função do habitat terrestre, e os testes de crescimento e reprodução com organismos aquáticos (Chlorella vulgaris e Daphnia magna, respectivamente) para avaliar a função de retenção do solo foram realizada. Os resultados demonstraram que em relação à função do habitat, a reprodução de F. candida foi o desfecho mais sensível (EC50 = 0,288 mg ia./kg), seguido pelo comportamento de evitação de E. andrei (EC20 = 1,75 mg ia./kg). A evitação de F. candida e a reprodução de E. andrei e E. crypticus não foram afetadas pelo diazinon. Os testes de toxicidade com organismos aquáticos mostraram que a função de retenção do solo foi insuficiente para prevenir os efeitos do diazinon no crescimento de microalgas (EC50 B ≤.742 mg / L e EC20 B ≤.223 mg / L) e na reprodução do cladócero ( EC50 B ≤,00771 mg / L e EC 20 B ≤,00646 mg / L). Os resultados sugeriram que o diazinon exerceu efeitos tóxicos mesmo na diluição correspondente à dose recomendada, o que torna seu uso indevido uma questão de preocupação ambiental. Além disso, o presente estudo destacou a importância e a natureza complementar da avaliação das funções de habitat e retenção para uma avaliação de risco ecológico em sistemas tropicais.University of Coimbra, PortugalUniversidad Nacional, Costa RicaInstituto Regional de Estudios en Sustancias Tóxica

Exploring the use of species sensitivity distributions to define protective limits for the use of organic wastes as soil amendments

Fundação para a Ciência e a Tecnologia. Grant Numbers: SFRH/BPD/110943/2015, SFRH/BPD/84140/2012, PTDC/AAC – AMB/119273/2010The use of organic wastes as soil amendments can be an important measure to improve soil quality and reduce waste accumulation and landfilling. However, the potential contaminant loads of such wastes, can be a source of environmental concern. Consequently, legislation has been developed to regulate the use of these wastes in agricultural soils. However, the regulations only consider chemical parameters, which are insufficient to establish the level of environmental risk. A possible solution is the use of species sensitivity distributions (SSDs), employing ecotoxicological data from test batteries that could be incorporated into legislation. In the present study, 2 different hazardous concentrations affecting 5 and 50% of the soil community (HC5 and HC50, respectively) were determined using ecotoxicological data (effect concentrations, 10 and 50% [EC10 and EC50, respectively]) for 5 different wastes. The results demonstrate that, as expected, current legislative thresholds do not translate to environmental risk/protection and that SSDs may be an important tool allowing the simple inclusion and interpretation of ecotoxicological data from test batteries in legislation. On the other hand, SSDs must be used with caution because there are still doubts about their actual value in risk prediction and about which estimates provide adequate protection. For instance, the use of HC50EC10 values is not recommended; these values overlap with the more conservative HC5EC50 data, highlighting the fact that the use of lower effect concentrations may not always provide the most protective approach. Also, hazardous concentrations need to be calibrated at the field or semifield level, to verify environmental protection in different soils/environments and the adequacy of standard test organisms

Impact of no-tillage versus conventional maize plantation on soil mesofauna with and without the use of a lambda-cyhalothrin based insecticide : A terrestrial model ecosystem experiment

Different soil management in crop cultures like maize can produce a variety of effects on soil fauna. Conventional cropping includes soil tillage, promoting organic matter losses and destruction of soil structure, whereas no-tillage cropping includes a herbicide application which can potentially affect soil fauna. In both management systems, insecticides are often used, such as pyrethroid insecticides, to prevent insect pests. Understanding the impact of these different cropping systems in their different phases on soil mesofauna and investigating the ability of soil communities to recover may provide important information to select cropping strategies which are more protective of soil biodiversity. With this aim, a terrestrial model ecosystem experiment was performed over eighty-nine days. The test treatments, all including maize, were: undisturbed soil; conventional tillage; conventional tillage with insecticide; no-tillage soil with herbicide; no-tillage soil with herbicide and insecticide. In each TME, soil samples from 0 to 5 and 5-10 cm of the top layer were collected from which collembolans and mites were identified to species, genus or subfamily level, and enchytraeid abundance was determined. Soil tillage did not affect soil communities, but insecticide application did. For collembolans and enchytraeids, the impact of the insecticide was independent of soil management, but for mites, insecticide impact was longer in conventional tillage than in no-tillage system. Changes on collembolan abundance, in general, did not promote changes in mean community trait values and functional diversity. Data suggest that no-tillage management is more protective to soil fauna than conventional tillage.Peer reviewe