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Assessing the Impact of Soil Amendments made of processed Biowaste Digestate on Soil Macrofauna using two different Earthworm Species
Abstract
Fermentation in combination with subsequent composting of biowaste is a preferred method for municipalities to recycle organic byproducts and transform them into useful end products for soil amelioration or plant fertilization. These compost products, especially if obtained from household wastes, can be a source of hazardous components, e.g. heavy metals, pathogens, synthetic chemicals or toxic organic compounds. An avoidance test with two earthworm species (Eisenia fetida and Aporrectodea caliginosa) was conducted to assess the impact of differently processed biowaste based digestate products on soil invertebrates. Body weight changes were recorded, as well as differences in effects on adult versus juvenile earthworms.
While E. fetida showed no avoidance towards the digestate products (negative avoidance, meaning that the tested products were preferred, of 80 to 100 %), A. caliginosa rejected the crude biowaste digestate compost in higher concentrations (avoidance of 45 %), but not the agglomerated or pelletized variants. A clear weight gain of up to 25 % was observed only for individuals of E. fetida. The developmental stages of the worms were not crucial for the outcome of the avoidance test.
Based on the results of this study the application of biowaste products on arable land cannot be recommended without constraints.
... Aporrectodea caliginosa (Ross et al., 2017). Although numerous hypotheses have been proposed to explain digestate toxicity (ammonia, salinity, oxygen deficiency, heavy metals), none has been completely verified or rejected. ...
... Several studies focused on solid digestates (Pivato et al., 2016;Renaud et al., 2017;Ross et al., 2017;Sizmur et al., 2017) that were later buried in the soil, so these authors did not assess earthworm surface foraging immediately after spreading. To our knowledge, this is only the second study (after Natalio et al. (2021)) to propose a microcosm experiment for assessing liquid digestate toxicity. ...
... The lack of significant differences in weight change between the treatments as well as the toxic effect shown in the microcosm experiments tends to favor the first hypothesis of a toxic effect. Indeed, Ross et al. (2017) observed that A. caliginosa avoided soil layers containing digestate and Ernst et al. (2008) found that A. caliginosa could not feed on raw digestate (weight loss was observed in these 1500 mm 3 mesocosms). This avoidance of digestate could explain why some A. caliginosa came to the surface in the field after digestate spreading, which is not a common behavior for endogeic species. ...
La méthanisation agricole des effluents animaux est une pratique en fort développement en France. Elle produit de l’énergie renouvelable (biogaz). La valorisation des digestats au champ, comme celle des effluents non méthanisés, permet le retour au sol de nutriments et de matière organique, ce qui diminue le besoin en engrais minéraux et entretient les stocks de C des sols. Le traitement et l’épandage de ces produits peut aussi induire l’émission de gaz à effet de serre et de contaminants. La méthanisation agricole influence ces impacts : pour les maitriser, il faut comprendre comment la digestion des effluents avec des déchets importés modifie les cycles du C et du N à l’échelle de la ferme. Cette question a été traitée en s’appuyant sur un cas d’étude à l’INRAE de Nouzilly (Centre – Val de Loire) : une exploitation agricole avec un méthaniseur traitant les effluents de son élevage bovin et divers déchets organiques. Lors de l’essai au champ MétaMétha, nous avons comparé les flux d’azote au cours d’une rotation culturale fertilisée avec des engrais minéraux, des lisiers et fumiers bovins, ou des digestats issus de ces effluents. Les digestats se substituent bien aux engrais minéraux, mais ils sont sensibles à la volatilisation d’ammoniac (NH3). Les vers de terre peuvent être négativement impactés juste après l’épandage de digestat ou de lisier, mais les effets sont similairement positifs après 2 ans d’apports de matière organique. Nous avons ensuite évalué les modèles STICS et SYS-Metha pour simuler respectivement l’essai au champ et le traitement des digestats. Ces modèles ont été couplés pour simuler les flux de C et N à l’échelle de la ferme. Avec de forts imports de déchets, la méthanisation favorise la substitution des engrais minéraux, le stockage de C dans les sols, mais aussi les émissions de NH3. Ce travail permet de mieux évaluer les conséquences de l’introduction d’un méthaniseur dans une exploitation agricole et ainsi d’optimiser la filière.
... These results suggest that digestates influence earthworm behavior (surface foraging). The toxicity of solid or liquid digestate toxicity was assessed in the laboratory for diverse soil organisms (Tigini et al., 2016), including the epigeic earthworm Eisenia fetida (Krishnasamy et al., 2014;Pivato et al., 2016;Renaud et al., 2017) and the endogeic earthworm Aporrectodea caliginosa (Ross et al., 2017). Although numerous hypotheses have been proposed to explain digestate toxicity (ammonia, salinity, oxygen deficiency, heavy metals), none has been completely verified or rejected. ...
... Several studies focused on solid digestates (Pivato et al., 2016;Renaud et al., 2017;Ross et al., 2017;Sizmur et al., 2017) that were later buried in the soil, so these authors did not assess earthworm surface foraging immediately after spreading. To our knowledge, this is only the second study (after Natalio et al. (2021)) to propose a microcosm experiment for assessing liquid digestate toxicity. ...
... The lack of significant differences in weight change between the treatments as well as the toxic effect shown in the microcosm experiments tends to favor the first hypothesis of a toxic effect. Indeed, Ross et al. (2017) observed that A. caliginosa avoided soil layers containing digestate and Ernst et al. (2008) found that A. caliginosa could not feed on raw digestate (weight loss was observed in these 1500 mm 3 mesocosms). This avoidance of digestate could explain why some A. caliginosa came to the surface in the field after digestate spreading, which is not a common behavior for endogeic species. ...
Anaerobic digestion is increasingly used in Europe to treat organic substrates and produce biogas as a renewable energy source. The residual matter (digestate) is used in agriculture as an organic fertilizer. The study aims at assessing the impact of digestate application in the field on earthworms from the short term (few hours) to the long term (two years), and at investigating under laboratory conditions the role of ammonia and earthworm behavior on digestate toxicity in the short term. First, we studied earthworm communities in fields fertilized with digestates, cattle effluents, or chemical fertilizers for two years. Earthworm abundance was assessed before and after the fertilization event of the third year. Earthworm mortality at the soil surface was also assessed immediately after fertilization. Next, the toxicity of digestate or ammonia solutions on Aporrectodea caliginosa and Lumbricus terrestris was measured in microcosms (110 cm³) to better understand the short-term toxicity (two weeks). Finally, we spread digestate (40–80 t ha⁻¹) on soil columns (5300 cm³) and used X-ray tomography after two weeks to assess the burrowing behavior of earthworms in the cores. Earthworm abundance was 150% higher in the fields treated for two years with digestates or cattle effluents compared to the field treated with chemical fertilizers. 0.5 to 2% of adult earthworms died at the soil surface a few hours after liquid digestate and cattle slurry spreading (18 to 24 t ha⁻¹). The digestate (10% to 20% (fresh digestate/dry soil)) and ammonia were also lethal to earthworms in the microcosms within two weeks. In contrast, no mortality occurred inside soil columns two weeks after digestate spreading; A. caliginosa avoided the soil surface with high digestate inputs. This case study highlighted the potential short-term toxicity of digestate (a few hours), which evolved towards a neutral to positive impact in the field in the longer term (from two weeks to two years). Further research is needed to understand the impact of diverse solid and liquid digestates on soil macrofauna in different soils.
... Earthworms can be broadly defined into three ecological groups: epigeic, endogeic and anecic (Bouché, 1977), though species are found corresponding to multiple categories (Bottinelli et al., 2020). Epigeic (litter dwelling) earthworms actively avoided digestate amended soils where possible (Clements, 2013;Ross et al., 2017). Whilst endogeic (topsoil dwelling) did not express such clear avoidance behaviour (Ross et al., 2017), their biomass decreased after digestate application (Ernst et al., 2008;Bhogal et al., 2016). ...
... Epigeic (litter dwelling) earthworms actively avoided digestate amended soils where possible (Clements, 2013;Ross et al., 2017). Whilst endogeic (topsoil dwelling) did not express such clear avoidance behaviour (Ross et al., 2017), their biomass decreased after digestate application (Ernst et al., 2008;Bhogal et al., 2016). In contrast epi-anecic (subsoil dwelling who collect food from soil surface) earthworms responded positively to digestate application (Ernst et al., 2008). ...
... Klärschlämme enthalten häufig Schwermetalle wie Kupfer, Zink oder Cadmium, insbesondere dort, wo die Industrie zum Abfallstrom beiträgt (Bünemann et al. 2006). Auch Bioabfälle können durch Kontamination und/oder ungenügende Trennung und Aufbereitung des Substrates Schwermetalle, Chemikalien-und Medikamentenrückstände oder schädliche organische Verbindungen enthalten (Ross 2017;Ross et al. 2017 2 Auswirkungen auf biologische Bodeneigenschaften Anthropogene Bodenveränderungen und -belastungen 6.6.5 ...
Zusammenfassung
Die Ausbringung von abbaubarem organischem Material wirkt sich in den meisten Fällen positiv auf die biologische Aktivität sowie die Vielfalt der mikrobiellen Arten (Bakterien und Eukaryoten) im Boden aus.
Grundsätzlich gilt dies auch für Bioabfälle, allerdings lassen sich kaum generelle Aussagen treffen, da die Wirkung auf das Bodenleben zu stark von der Qualität des Abfalls abhängt. Einige Bioabfallarten, z.B. aus der Olivenölgewinnung, können zudem ganz spezielle Probleme mit sich bringen, die eine Anwendung als Düngeprodukt oder Bodenhilfsstoff erschweren oder vollständig ausschließen. Insbesondere kommunale Abfälle können außerdem Plastik enthalten, das durch Abrieb und Zerkleinerung zu Partikeln zerfällt, die von Bodenorganismen unabsichtlich aufgenommen werden können. Hinsichtlich Abundanz und Diversität der Mikroorganismen ist der Nährstoffgehalt des Bioabfalls eine wesentliche Steuergröße. Von besonderer Bedeutung sind dabei Stickstoff, Phosphor, Kalium und Kohlenstoff. Die Applikation organischer Reststoffe als Dünger kann auch einen entscheidenden Beitrag zur Förderung von Nützlingen und zur Bekämpfung von schädlichen Makro- und Mikroorganismen leisten, da physikalische und chemische Bodeneigenschaften so verändert werden, dass günstige Bedingungen für erwünschte detritivore Gemeinschaften und sonstige Nützlinge entstehen. Zum Teil werden die Nützlinge sogar direkt mit dem organischen Material eingetragen, und Schädlinge können so durch Konkurrenz oder Prädation zurückgedrängt werden oder finden keine geeigneten Lebensbedingungen mehr vor.
Krankheitserreger sind in organischen Abfällen reichlich vorhanden, mittels Pasteurisierung (1h bei 70°C) werden die meisten Humanpathogene jedoch abgetötet. Damit wird ein direktes Gesundheitsrisiko nahezu ausgeschlossen und der zunehmenden Verbreitung von bakteriellen Antibiotikaresistenzgenen in der Umwelt entgegengewirkt.
... Indeed, incomplete degradation during anaerobic digestion will lead to remnants of biodegradable microplastics and potential leakage of bioplastics into the environment if the digestate is used for agronomic application (Cucina et al., 2021). In parallel, in future work, specific attention will be paid on the investigation of the potential ecotoxicity of the various digestates produced in several aquatic and terrestrial ecosystems (Ross et al., 2017). ...
The development of selective biowaste collection in most European countries provides new opportunities for the anaerobic digestion sector. In parallel, extensive development of biodegradable plastics like polylactic-acid (PLA) and polyhydroxybutyrate (PHB), which facilitates the replacement of conventional plastics, has taken place in the past decade. This study investigated anaerobic co-digestion in semi-continuous reactors of biowastes (75% VS) and biodegradable plastics (25% Volatil Solids, PLA and PHB). PHB was estimated to be fully biodegraded in the reactors. By contrast, PLA accumulated in the reactor, and an average biodegradation of 47.6 ± 17.9% was estimated during the third hydraulic retention time. Pretreatment of PLA, by thermo-alkaline hydrolysis at 70 °C, with 2.5 w/v of Ca(OH)2 for 48 h, improved the biodegradation yield of PLA to 77.5 ± 9.3%. Finally, it was highlighted that PLA or PHB addition to the feed did not further affect the agronomic properties of the digestate.
... Il semble cependant que l'apport de digestats induise une augmentation de la biomasse et de l'abondance des vers de terre au niveau des sols agricoles (Koblenz et al., 2015). Ces résultats ne représentent cependant pas un consensus, puisqu'une autre étude démontre l'effet délétère des digestats de méthanisation sur les vers de terre (Ross et al., 2017). Pour résumer, que l'on considère les microou les macroorganismes du sol, les résultats disponibles dans la littérature scientifique sont à ce jour contradictoires ; chaque étude rapportant des effets propres à des digestats particuliers, appliqués dans des conditions expérimentales uniques, rendant les conclusions actuelles peu génériques. ...
... 80%, however what was observed was the negative avoidance (Fig. 3), in which the worms gave preference for the residues and composts. This phenomenon is usually related to the presence of food sources in the sample (Ross et al., 2017), such as the OM contained in the composts and residues, which is more attractive for E. fetida than the control soil, predominantly composed of sand. ...
The main goal of this article is to study the vermicomposting and composting process of black wattle bark bagasse with bovine manure mixed in different proportions and to evaluate if the composts generated have physicochemical and toxicological aspects suitable for its use as fertilizers. The physicochemical tests of the studied residues and their composts demonstrated that bovine manure and black wattle bark bagasse are sources of macro and micronutrient, but none of the composts showed relevant differences between nutrient concentrations. The final pH of the composts remained acidic, varying between 4.6 and 5.80. During composting the maximum temperature reached by the composts was 29.5 °C, reached by the 20% black wattle bark bagasse compost. The germination test and root elongation performed with Lactuca sativa showed that the black wattle bark bagasse and bovine manure presented toxic effects, but the composting process was capable to reduce their toxicity to safe levels in the composts V5 and C5. Chronical and acute toxicity tests revealed no toxic effect of the composts on Eisenia fetida; the same happened with the avoidance test, which indicated negative avoidance of earthworms. Thus, it is concluded that the biotransformation of black wattle bark bagasse in organic fertilizer is viable through composting process and that composts V5 and C5 have adequate physical, chemical and toxicological characteristics for use as agricultural fertilizer. However, application to Cu-sensitive crops should be avoided due to the high concentration of this element on the composts.
... Die Inhalte dieses Kapitels wurden zum Teil bereits veröffentlicht in Ross et al. (2017b): "Assessing the Impact of Soil Amendments made of processed Biowaste Digestate on Soil ...
Im Rahmen dieser Arbeit sollten Einsatzmöglichkeiten und -grenzen von kompostierten und durch Agglomeration oder Pelletierung weiter aufbereiteten Bioabfall-Gärresten untersucht werden. Außerdem sollte geprüft werden, ob durch verschiedene Zuschlagstoffe die Eigenschaften der Produkte so verbessert werden können, dass ein marktfähiges Düngeprodukt entsteht. Dazu wurden ein Feldversuch, Gefäß-, Rhizoboxen- und Bodenatmungsversuche, phytotoxikologische Tests und Regenwurm-Vermeidungstests durchgeführt. Die Ergebnisse können wie folgt zusammengefasst werden: Die Stickstoffverfügbarkeit von kompostierten Gärprodukten aus Bioabfällen ist gering, der Gehalt an Phosphor und Kalium aber hoch. Langfristig sind so der Aufbau eines Nährstoffdepots im Boden und die Einsparung anderer Dünger möglich. Die Produkte enthalten zudem basisch wirksame Bestandteile, welche die Kalkung teilweise ersetzen können. Komposte und Gärprodukte aus Bioabfällen können zur Steigerung der Humusgehalte im Boden beitragen. Ca. 80 % des enthaltenen Kohlenstoffs liegt in stabilisierter Form vor und kann im Boden sequestriert werden. Problematisch sind hohe Schwermetall- und Störstoffgehalte. Die gesetzlich vorgegebenen Grenzwerte wurden in 50 % der getesteten Chargen überschritten. Phytotoxische Effekte wurden nur in Einzelfällen festgestellt und waren nicht dosisabhängig, sondern traten punktuell auf. Die Aktivität der Mikroorganismen im Boden wurde durch Anwendung der Gärprodukte gefördert. Der Einfluss der Gärprodukte auf Regenwürmer konnte nicht eindeutig bestimmt werden. Eine Einschränkung der Habitatfunktion nach Gärproduktanwendung wurde nicht festgestellt. Die Aufbereitung durch Agglomeration oder Pelletierung ist möglich, ohne dass die wesentlichen positiven Eigenschaften davon beeinträchtigt werden. Durch Beimengung von Zuschlagstoffen können die Düngewirkung und die physikalischen Eigenschaften der Produkte verändert werden. Dies reduziert jedoch auch den Gehalt an stabiler organischer Substanz.
Note this review is best viewed on line at http://www.compostinfo.info/ where updates and additional resources are available.
The aim of this review is to collate the large body of existing, and apparently forgotten, information about composting mechanically separated fractions of municipal solid waste (MSW) including sampling and sample preparation issues; and then to present this information in a form that is easily accessible to the UK waste management industry, environmental consultants and researchers.
The volume of material is enormous, and only a fraction of it can be referenced in a conventional review. Hence this review operates in conjunction with an on-line bibliography at (www.compostinfo.info), which currently provides access to a bibliography of around 1,600 references linked to mixed waste composting. The review is intended to provide a general grounding in the subject and to sign post readers to sources of further information. The review is not intended as a “design and build manual” nor does it provide definitive guidance on legal, regulatory, policy or health and safety issues.
The review covers the following topics.
• Composting: past and present: past and recent UK and European composting experience
• Feedstocks and composition: the physical, chemical and biological characteristics of mechanically segregated MSW used for composting
• Sampling and analysis: Methods for quantifying and assessing the performance of mechanical separation, composting and refining systems, in particular sample collection, assessment and preparation. I.e. sampling and sample handling, designing the sampling scheme, sample collection, sub-sampling, sample preparation, preservation and transport, interlaboratory comparisons, health and safety issues, physical methods, chemical methods and biological methods.
• Biology of composting: the terms used, a process description and review of process optimisation.
• Pre-processing methods: technologies used for compost feedstock preparation (separation technologies such as, hand picking, size separation, density based separation, use of electric or magnetic fields; size reduction approaches; process integration; other conditioning approaches; and materials handling issues).
• Composting techniques: turned windrow approaches, open aerated systems, and contained systems
• Refining and packaging: separation processes used in refining, fine milling and pelleting, mixing and bagging, other techniques
• Health and safety, emissions and emissions control: considering in particular: leachate, odour and volatile organic compounds, dust, bioaerosols and other health risks, vermin / birds / insects and fire risks
• Product quality and environmental impacts: The quality of the composts produced by from mechanically segregated fractions of MSW, including: major chemical properties, trace elements, organic pollutants, inerts, microbial and pathogen issues, maturity and stability
• End-uses: for composts produced by from mechanically segregated fractions MSW considering: landfill applications, land restoration, soil improvement, mulches, growing media, and composting as a pre-treatment for landfill
• Operational and Strategic Issues: the role MSW composting can play in sustainable development, regulations standards and guidelines for compost products and the composting process, and compost marketing.
This review has been compiled to provide generic guidance only. r3 environmental technology limited, AEA Technology PLC and the SITA Environmental Trust accept no responsibility whatsoever for any loss or prosecution resulting from acting on the information contained herein. Adherence to any recommendations or information does not necessarily imply endorsement by r3 environmental technology limited, AEA Technology PLC and the SITA Environmental Trust; neither does it necessarily ensure compliance with the respective regulatory requirements. It is strongly suggested that specialist advice be sought where appropriate.
The dynamics of earthworm populations were investigated in continuously-cropped, conventional disk-tilled corn agroecosystems which had received annual long-term (6 years) amendments of either manure or inorganic fertilizer. Earthworm populations were
sampled at approximately monthly intervals during the autumn of 1994 and spring and autumn of 1995 and 1996. The dominant earthworm species were Lumbricus terrestris L. and Aporrectodea tuberculata (Eisen), which comprised 50–60% and 8–13%, respectively, of the total annual earthworm biomass. Lumbricus rubellus (Hoffmeister) and Aporrectodea trapezoides (Dugés) were much less abundant and contributed a small fraction of total earthworm biomass. Earthworm numbers and biomass were significantly greater in manure-amended plots compared to inorganic fertilizer-treated plots during the majority of the study period. Seasonal fluctuations in earthworm numbers and biomass were attributed to changes in soil temperature and moisture, and cultivation. Unfavorable climatic conditions in the summer and autumn of 1995 caused earthworm abundance and biomass to decline significantly. Mature L. terrestris, L. rubellus and A. tuberculata were most abundant in May and June of 1995 and 1996, and cocoon production was greatest in June and July 1995 and June 1996. Recruitment of juveniles of Lumbricus spp. and Aporrectodea spp. into earthworm communities occurred primarily in the autumn. Long-term amendments of manure or inorganic fertilizer did not change the species composition of earthworm communities in these agroecosystems. The earthworm populations in both manure and inorganic fertilizer plots have declined significantly after 5 years of continuously-cropped corn.
The effects of earthworm (Eisenia fetida) activity on soil pH, dissolved organic carbon (DOC), microbial populations, fraction distribution and bioavailability of heavy metals (Zn, Cu, Cr, Cd, Co, Ni, and Pb) in five Chinese soils were investigated using pot experiments. A three-step extraction procedure recommended by the European Community Bureau of Reference (BCR; now Standards, Measurements and Testing Programme of the European Community) was used to fractionate the metals in soils into water soluble, exchangeable and carbonate bound (B1), Fe-oxides and Mn-oxides bound (B2) and organic matter and sulfide bound (B3). After the soils were treated with earthworms, the soil pH, water-soluble metal fraction and DOC increased. A significant correlation was obtained between the increased DOC and the increased metals in the water-soluble fraction. The heavy metals in fraction B1 increased after earthworm treatments, while those in fraction B3 decreased. No significant differences were observed for heavy metals in fraction B2. The microbial populations in soil were enumerated with the dilution plate method using several media in the presence of earthworms. The microbial populations increased due to earthworm activity. The biomass of wheat shoots and roots, and the heavy metal concentrations in wheat roots and shoots, were also increased due to the earthworm activity. The present results demonstrated that earthworm activity increases the mobility and bioavailability of heavy metals in soils.
Laboratory incubation experiments were conducted to examine the effect of earthworm (Pheretima sp.) activity on soil pH, zinc (Zn) fractionation and N mineralization in three soils. No Zn uptake by earthworms was observed. Zinc addition decreased pH of red soil (soil 1) and hydragric paddy soil (soil 3) by 0.5 and 0.2 unit, respectively, but had no effect on alluvial soil (soil 2). The effect of Zn on soil pH was possibly due to a specific adsorption mechanism between Zn and oxides. Earthworm activity significantly decreased the pH of the red soil, a key factor affecting Zn solubility, but not of the other two soils. Earthworm activity significantly increased DTPA-Zn (DTPA-extractable) and OxFe-Zn (NH2OH-HCl-extractable) in the red soil, but had little effect on other fractions. In the alluvial soil, earthworm activity significantly increased OxFe-Zn but decreased organic-Zn (organic-associated Zn). In the hydragric paddy soil, earthworm activity significantly increased MgCl2-Zn (MgCl2-extractable) and organic-Zn. The level of CaCl2-extractable Zn in all three soils was not affected by earthworm activity. Nitrogen mineralized as a result of earthworm activity was equivalent to 110, 120 and 30 kg N ha-1 in soils 1, 2 and 3, respectively. Zinc added at rates less than 400 mg Zn kg-1 did not seem to affect the activity of N-mineralizing microorganisms. The present results indicated the possibility of increasing the metal bioavailability of relatively low level metal-contaminated soils, with a higher organic matter content, by earthworm inoculation.
The feeding requirements of earthworms have not been fully established. A vermiculite matrix was used to determine the dietary effects of various organic substances. Vitamins, DNA, and humic acid as additives improved growth and allowed reproduction of Eisenia fetida in a cellulose-based medium. Mature worms were not able to adapt to the medium and 20-day-old worms were used. Rates of growth and cocoon production were slightly less in a defined medium (7% organic content) than in a cow-manure control medium (70% organic content). The medium is likely to prove useful as a reference medium for obtaining biological information.
Earthworms are used in an increasing number of microcosm experiments that investigate their behaviour and biology or that consider earthworms an environmental factor that influences soil properties and biological interactions. However, there exists no standardized protocol for performing comparable studies. After giving a short overview of the different experimental approaches using earthworms as model organisms, the present paper provides recommendations for the planning and execution of earthworm experiments that help in achieving comparable results. The recommendations, summarized in a workflow diagram, pertain to the acquisition, treatment and description of earthworms for experimentation, the description and preparation of test soils and the criteria that should be met for valid experimental results.
This review presents the current state of knowledge on the relationship between the environment and the use of municipal waste compost in terms of health risk assessment. The hazards stem from chemical and microbiological agents whose nature and magnitude depend heavily on the degree of sorting and on the composting methods. Three main routes of exposure can be determined and are quantified in the literature: (i) The ingestion of soil/compost mixtures by children, mostly in cases of pica, can be a threat because of the amount of lead, chromium, cadmium, PCDD/F and fecal streptococci that can be absorbed. (ii) Though concern about contamination through the food chain is weak when compost is used in agriculture, some authors anticipate accumulation of pollutants after several years of disposal, which might lead to future hazards. (iii) Exposure is also associated with atmospheric dispersion of compost organic dust that convey microorganisms and toxicants. Data on hazard posed by organic dust from municipal composts to the farmer or the private user is scarce. To date, microorganisms are only measured at composting plants, thus raising the issue of extrapolation to environmental situations. Lung damage and allergies may occur because of organic dust, Gram negative bacteria, actinomycetes and fungi. Further research is needed on the risk related to inhalation of chemical compounds.
Earthworms play key roles in soils and sub-lethal effects of environmental toxicants on these organisms should be taken seriously, since they might have detrimental effects on higher ecological levels. In laboratory experiments we have assessed sub-lethal effects (body mass change and cast production) of imidacloprid on two earthworm species commonly found in different agricultural soils (Lumbricus terrestris and Aporrectodea caliginosa). After 7 days of exposure in contaminated soil, a significant loss of body mass was found in both species exposed to imidacloprid concentrations as low as 0.66 mg kg(-1) dry soil. These losses ranged from 18.3 to 39% for A. caliginosa and from 7.4 to 32.4% for L. terrestris, respectively. Changes in cast production, a new biomarker previously validated using L. terrestris, was assessed by soil sieving using the recommended mesh size (5.6 mm) for L. terrestris and three different mesh sizes for A. caliginosa (5.6, 4 and 3.15 mm). The 4 mm mesh size proved to be the most suitable sieve size for A. caliginosa. Cast production increased by 26.2% in A. caliginosa and by 28.1% in L. terrestris at the lowest imidacloprid concentration tested (0.2 mg kg(-1) dry soil), but significantly decreased at higher concentrations (equal to and above 0.66 mg kg(-1) dry soil) in both earthworm species after the 7 days exposure experiment. These decreases in cast production ranged from 44.5 to 96.9% in A. caliginosa and from 42.4 to 95.7% in L. terrestris. The EC(50) for cast production were 0.84 (L. terrestris) and 0.76 mg kg(-1) dry soil (A. caliginosa), respectively. The detected sub-lethal effects were found close to the predicted environmental concentration (PEC) of imidacloprid, which is in the range of 0.33-0.66 mg kg(-1) dry soil. The biomarkers used in the present study, body mass change and changes in cast production, may be of ecological relevance and have shown high sensitivity for imidacloprid exposure of earthworms. The measurement of changes in cast production should be considered for inclusion in current standard tests.
Terrestrial avoidance behavior is proposed as a fast and cost-effective method for assessing effects of pesticides on earthworms. Tropical species however, have rarely been used in avoidance tests. Avoidance tests were performed with Perionyx excavatus, a tropical species, and Eisenia andrei as the standard species, using chlorpyrifos and carbofuran in artificial and natural soil. Earthworms were exposed to concentrations of 1-900 (chlorpyrifos) and 1-32 (carbofuran)mg a.i. kg(-1) dry soil in a two-chamber system under tropical conditions (26+/-2 degrees C, 48 h). No significant difference was found in the control tests comparing the two soils used, suggesting soil type did not affect the distribution of the worms. The results suggest a higher sensitivity of E. andrei, with EC50S for the effect on avoidance behavior for both pesticides being a factor of 2-3 lowers than for P. excavatus. Earthworm avoidance tests with local species should therefore be used with caution when applied as a tool for pesticide risk assessment in the tropics. Endpoints generated through avoidance tests in this study are shown to be less sensitive than reproduction and more sensitive than survival. This was further confirmed by literature data available. Earthworm avoidance tests therefore can only replace survival tests as an initial screening tool for risk assessment.
Anaerobic digestion is an optimal way to treat organic waste matter, resulting in biogas and residue. Utilization of the residue as a crop fertilizer should enhance crop yield and soil fertility, promoting closure of the global energy and nutrient cycles. Consequently, the requirement for production of inorganic fertilizers will decrease, in turn saving significant amounts of energy, reducing greenhouse gas emissions to the atmosphere, and indirectly leading to global economic benefits. However, application of this residue to agricultural land requires careful monitoring to detect amendments in soil quality at the early stages.
For ecotoxicological assessments ot contaminated or remediated soils pointing to the habitat function of soils for bioccnoses, standardized tests with earthworms (acute test, reproduction test) arc available among others. Tests used for routine applications should be sensitive and indicate impacts on tesr organisms after short tost periods. The usually applied earth¬worm tests do not satisfactorily fulfil these criteria. Therefore, in rhc present work, a behavioural test with earthworms (test criterion: avoidance) was investigated in detail using unconrami-nated, artificially contaminated and originally contaminated soils. It was demonstrated that the avoidance behaviour is primarily determined by pollutants, and not by chemical-physical soil properties. The sensitivity of rhe presented test reaches the sensitivity of established tests. For waste sites, a considerably higher sensitivity was determined. An avoidance behaviour of at least 80% of the worms leaving rhc soil to be assessed is proposed as a criterion for roxieiiy.
Die Anwendung von Biokohlen in der Landwirtschaft gewinnt durch die positiven Aspekte der Kohlenstoffsequestrierung, Bodenverbesserung und eines erhöhten Pflanzenwachstums in den letzten Jahren an Bedeutung. Deshalb geht die vorliegende Arbeit den Fragen nach, welche Wirkungen unterschiedliche Biokohlen in Kombination mit oder ohne Gärrest und / oder Stickstoffdünger auf die Bodenchemie, Bodenbiologie und Wachstum, Entwicklung, Ertrag, Ertragsstruktur, Nährstoffe sowie Qualität von Nutzpflanzen haben. Außerdem wurden die Effekte unterschiedlicher Biokohlen auf die Wurzelmorphologie von Sommerweizen quantifiziert. Eine weitere Frage war, inwiefern Biokohlen Stickstoffquellen sorbieren. Es wurden ein Feldversuch und mehrere Gefäßversuche durchgeführt, um die Änderungen der Bodenchemie, den Einfluss auf die Bodenbiologie am Beispiel von Collembolen und die Pflanzenparameter zu bestimmen. Für die Wurzeluntersuchungen wurden Rhizoboxversuche durchgeführt und zur Quantifizierung der Stickstoffsorption ein in vitro Versuch angelegt. Die Ergebnisse der Feld- und Gefäßuntersuchungen zeigten, dass die Biokohlen die Bodeneigenschaften positiv beeinflussten. Die Biokohlen nahmen keinen konsistenten Einfluss auf die Erträge von Kulturpflanzen. Die Nährstoffgehalte der Kulturpflanzen konnten zum Teil positiv beeinflusst werden. Die Collembolenabundanzen zeigten sowohl in der Feldstudie als auch im Gefäßversuch keine signifikanten Unterschiede zwischen den getesteten Biokohlen. Hohe Mengen der fermentierten HTC-Biokohle führten zu negativen Wirkungen auf die Collembolenabundanz im Gefäßversuch. Die Rhizoboxversuche zeigten einen positiven Einfluss der Pyro-Biokohle auf die oberirdische und unterirdische Trockenmasse sowie die Wurzelmorphologie von Sommerweizen. Unterschiedliche Stickstoffquellen wurden von der HTC-Biokohle stärker sorbiert als von der Pyro-Biokohle. Generell lässt sich aus den differenzierten Wirkungen der Biokohlen weitere Forschung mit dem Fokus Boden ableiten.
Surface invertebrates were collected in pitfall traps from beginning of June to end of October 1996 on fertilizer experiment in Akureyri, Northern-Iceland, where impact of long term use of N-fertilizer is studied. Totally 60 species of invertebrates were identified to species level. As a mean for the whole period 1.3–5.6 specimens/day were collected from the plots, dominated by mites and springtails. Flying insects were more frequently trapped on plots with low grass (Agrostis capillaris) compared to plots covered with taller grass species (Alopecurus pratensis). Fertilization decreased the number of inverte-brate species collected but increased substantially total number of specimens, especially number of mites and springtails. Number of mites and springtails was highest where ammonium nitrate was applied, and lowest where calcium nitrate was used. Number of earthworms decreased with fertilization and they disappeared at low soil pH where ammonium sulphate had been applied, while number of Prostigmata mites increased. Although fertilization in most cases increased number of specimens, management reduced number of trapped spiders and hemipterans, but after cutting catches of spiders and beetles increased in fertilized plots. Activity of most groups of invertebrates culminated at temperature peaks, apart from dipterans which culminate in spring and Isotomidae springtails and beetles which culminate in fall.
Earlier studies of post-mining soils near Sokolov, Czech Republic, showed that colonization of the spoil heaps by earthworms greatly changes the plant community composition and soil characteristics. The current study determined how colonization of heaps by the endogeic earthworm Aporrectodea caliginosa is affected by the vegetation, litter, and soil at sites of different ages. In one experiment, we measured the performance of A. caliginosa in 25-l microplots at four heaps of increasing age and successional stage (8, 15, 25, and 48 years). After 6 months, A. caliginosa number and biomass in microplots decreased in young heaps (8 and 15 years old), remained constant in the 25-year-old heap, and increased in the 48-year-old heap. In other words, A. caliginosa survival, growth, and reproduction increased with successional stage. In a second field experiment, we tested A. caliginosa performance in microplots containing different types of litter at two heaps at mid-successional stages (19 and 25 years old). After 12 months, A. caliginosa biomass and abundance were greater with grass litter than with shrub and tree litter, but were greater in the 25-year-old heap, which was dominated by shrubs, than in the 19-year-old heap, which was dominated by grasses. Together, the two experiments indicate that colonization of heaps by A. caliginosa is enhanced by succession and by remaining patches of early successional vegetation in heaps at mid-successional stages.
The uncontrolled discharge of large amounts of food waste (FW) causes severe environmental pollution in many countries. Within different possible treatment routes, anaerobic digestion (AD) of FW into biogas, is a proven and effective solution for FW treatment and valorization. The present paper reviews the characteristics of FW, the principles of AD, the process parameters, and two approaches (pretreatment and co-digestion) for enhancing AD of food waste. Among the successive digestion reactions, hydrolysis is considered to be the rate-limiting step. To enhance the performance of AD, several physical, thermo-chemical, biological or combined pretreatments are reviewed. Moreover, a promising way for improving the performance of AD is the co-digestion of FW with other organic substrates, as confirmed by numerous studies, where a higher buffer capacity and an optimum nutrient balance enhance the biogas/methane yields of the co-digestion system.
The effects of several organic and mineral fertiliser manurial regimes were compared on undisturbed and former opencast grassland. Earthworm casting, burrowing, and population data were recorded on two field trials over a number of years. Treatment responses were similar on opencast and undisturbed land. Topdressed poultry manure encouraged casting and burrowing to the surface. In contrast, NPK fertiliser discouraged these activities, the reduction in casting becoming larger at higher rates of application. Responses to urea were less consistent; alone, its effect was negative, but, whereas NPK fertiliser interacted negatively with manure, urea produced a positive interaction effect.Aggregate population indices were not significantly affected by treatments, behaviour patterns being apparently more sensitive to manurial inputs. However, within each population, one species of earthworm—thought to be responsible for most of the surface casting—varied in number in a pattern similar to that of activity measurements. Positive effects of poultry manure resulted mainly from increased organic returns under grazing. Adverse effects of fertiliser could not be explained by soil pH changes, but may have resulted from high salt concentrations or, from shifts in the species balance. The implications of the above findings for soil rehabilitation on opencast land, and for agriculture in general, are briefly considered.
The EU is committed to encourage biological treatments of organic waste as an alternative to landfill and also to enhance organic matter recycling. When these wastes are composted, the composition of the initial raw materials is very important in order to obtain a good quality product. In this article, the mineral composition of the organic fraction obtained from source-sorted collection (SC) and the organic fraction mechanically separated (MS) from mass-collected municipal solid waste was evaluated. Also, the compositions of these 2 raw materials that are used in the current Spanish municipal solid waste biological treatment facilities were compared. The mineral elements analyzed were the total content of the heavy metals Zn, Cu, Ni, Cr, Pb and Cd, and the plant nutrients P, K, Na, Ca, Mg, Fe and Mn. The results obtained were expressed on dry matter basis and on mineral matter basis. Important differences were detected between SC and MS samples, on both dry and mineral matter basis. In general, nutrient contents are higher in SC than in MS, and heavy metal contents are significantly lower in SC. Our results also support the idea that the heavy metal migration from the non-compostable materials to the decomposable matrix takes place from the beginning of the process while both types of materials are in contact.
Six earthworm species common to upland Scottish pasture were offered soil and seven plant species of equal nutritional status common to pastures to determine if any dietary preferences existed. An analysis of variance showed that food types were removed differentially (p < 0.001), although closer inspection of the data revealed that this was biased due to the relative rejection of two plant species, Ranunculus repens and Trifolium repens. The percentage of food removed by each earthworm species was different (p < 0.01) and was positively correlated (p < 0.05) with earthworm biomass. Certain earthworm species preferentially removed different amounts of food types under offer resulting in a significant food x earthworm interaction (p < 0.001). The endogeic earthworm species Octolasion cyaneum preferred soil compared with all other available food types. Lumbricus terrestris, preferred Poa annuabut, in comparative terms, rejected soil compared to the other food types thus being consistent with this species being considered anecic, i.e. feeding on both plant material and rarely on soil. In contrast, another anecic species, Aporrectodea longa had no obvious food preference but did reject R. repens relative to L. perenne and soil. The remaining earthworm species Allolobophora chlorotica, Aporrectodea caliginosa, and Lumbricus rubellus had no single preferred food choice, although A. chlorotica removed noticeably less soil than the other available food types.
Earthworm (Lumbricidae) populations were assessed in three replicated, field experiments with different management intensities conducted on grassland research farms on medium-textured mineral soils, located at Solohead (Co. Tipperary), Grange (Co. Meath) and Johnstown Castle (Co. Wexford), Ireland. The experiment at Solohead involved four levels of mineral fertilizer application (80, 175, 225 and 350kgNha−1), and the plots were rotationally grazed by dairy cows. Three levels of mineral fertilizer application were compared at Johnstown Castle (0, 225 and 390kgNha−1) and two at Grange (100 and 225kgNha−1), and the plots at these sites were rotationally grazed by suckler cows and followers or dry cattle.Between 10 and 15 earthworm species were recorded per site, with Allolobophora chlorotica and Aporrectodea caliginosa being dominant. Other abundant species included Aporrectodea rosea, Aporrectodea longa, Lumbricus terrestris, Lumbricus friendi, Lumbricusfestivus, Lumbricus rubellus and Satchellius mammalis. Mean earthworm population densities per treatment ranged from 203 to 324individualsm−2 and biomass from 60 to 176gm−2. ANCOVA revealed significant overall positive relationships between management intensity (as indicated by N application rate) and earthworm abundance (F=4.47, p
Earthworms can be used to treat solid organic waste. Many studies have reported the effect of temperature, moisture, and pH value on the growth, reproduction, and survival of earthworms in manure. A study of the influence of these parameters on the growth and survival of earthworms in municipal solid waste is presented in this paper. The growth and mortality of earthworms in municipal solid waste with different temperatures (15, 20, 25 degrees C) was studied for 70 days, with different pH values (5.1, 5.4, 6.5, 7.2, 8.6) for one day, and with different C/N ratios (26, 24, 22, 20, 17, 15) for 15 days. The following conclusions have been made: 1. The shortest growth period was 52 days at 25 degrees C, and the fastest growth rate was 0.0138 g per day. 2. A correlation between the growth rate and feed-conversion rate was determined. The largest weight-gain rate and feed-conversion rate at 19.7 and 21.9 degrees C was 0.0459 g/g ⋅day, 0.429 g/g ⋅day respectively. 3. The optimum pH value was in the range of 6.5~8.6. If the pH value was outside this range, the earthworm numbers decreased greatly (died). 4. The material conversion rate reached the peak value when the C/N ratio is 20 at 20degrees C. 5. The optimal fermentation period in municipal solid waste was 18 days.
Goal, Scope and Background
In a preliminary ecological risk assessment, potential adverse effects of contaminants are often evaluated by measuring chemical residues and comparing these with regulatory guidelines. However limitations with this approach with regards to establishing actual effects have resulted in the increasing usage of sublethal effects-based assays, including biomarkers, to evaluate the hazard posed by contaminants in the environment. In this study a number of effects-based endpoints in the earthworm Aporrectodea caliginosa were evaluated to determine their comparative sensitivity for assessment of adverse effects of soil contaminated with petroleum hydrocarbons.
Methods
Adult and juvenile earthworms were exposed for 4 weeks to sublethal concentrations of soil collected before and after remediation of a petroleum-contaminated site. A suite of endpoints were measured in these earthworms, including mortality, fecundity, growth, and juvenile maturation, and two less traditional endpoints, the biomarker, the neutral red retention assay (NRRA) and an avoidance behaviour test.
Results and Discussion
Cocoon viability in this species is not a reliable parameter to measure, due to low viability in controls and a high coefficient of variation. Growth in adult earthworms was a more sensitive parameter than cocoon production. Maturation and growth of juveniles have been proposed as more sensitive endpoints than adult cocoon production and growth respectively. This was not apparent in the growth parameters, but maturation of juveniles did appear to be more sensitive than cocoon production by adults. The NRRA was a more sensitive parameter than cocoon production, and the NRRA and growth were both affected at the lowest concentration tested. The NRRA response appeared to be more sensitive than growth, but NRRT was only evaluated in one soil only, while the other parameters were assessed in two soils. However, the NRRA has previously been found to be more sensitive than growth after exposure to a number of contaminants. The avoidance behaviour assay exhibited similar sensitivity to growth and fecundity and could therefore be useful as a simple pre-screening test.
Conclusion
The chronic endpoints, growth, cocoon production, and juvenile maturation parameters, were all sensitive endpoints for detecting exposure to the petroleum-hydrocarbon-contaminated soil. The NRRA was the most sensitive of the endpoints assessed and could be used as an early-warning indicator to predict adverse impacts. Avoidance behaviour could be used as a simple pre-screening test to evaluate contaminated soils prior to more extensive and invasive testing.
Recommendations and Perspective
Measuring chemical concentrations in environmental samples is not always useful, as the toxicological impacts of exposure to these concentrations are not always discernible. However, the use of effects-based endpoints, either in situ or in the laboratory using laboratory-reared earthworms, can account for the bioavailability of chemicals in the soil, and can therefore provide information on the toxicological impacts of exposure. The assays tested in this research were sensitive indicators of exposure, and therefore can be used to determine potential ecological risks at contaminated sites and to monitor the progress of remediation at these sites.
In the existing guidelines for earthworm toxicity testing, mortality is the only test criterion. Mortality is, however, not a very sensitive parameter, and from an ecological point of view growth and reproduction are more important for a proper risk assessment of chemicals in soil. In this study the growth and sexual development of juvenile earthworms were considered as test criteria in a standardized earthworm toxicity test. The effect of Cd, Cu, and pentachlorophenol on the growth and sexual development of juveniles of the species Eisenia andrei was studied in an artificial soil substrate. Two tests with Cd were carried out to study the effects of the mode of application of the food source (cow dung). EC50 (50% effective concentration) values for the effect of Cd, Cu and pentachlorophenol on the growth of E. andrei were 33–96, >100, and >32 mg kg-1 dry soil, respectively, and there was no observed effect at 18–32, 56, and 32 mg kg-1 dry soil, respectively. Sexual development of the earthworms was inhibited at 10 mg Cd kg-1 and 100 mg Cu kg-1 dry soil, but was not affected at the highest pentachlorophenol concentration tested (32 mg kg-1 dry soil). The results were the same whether the food was applied in a hole in the middle of the soil or mixed homogeneously through the soil.
For ecotoxicological assessments of contaminated or remediated soils pointing to the habitat function of soils for biocenoses,
standardized tests with earthworms (acute test, reproduction test) are available among others. Tests used for routine applications
should be sensitive and indicate impacts on test organisms after short test periods. The usually applied earthworm tests do
not satisfactorily fulfil these criteria. Therefore, in the present work, a behavioural test with earthworms (test criterion:
avoidance) was investigated in detail using uncontaminated, artificially contaminated and originally contaminated soils. It
was demonstrated that the avoidance behaviour is primarily determined by pollutants, and not by chemical-physical soil properties.
The sensitivity of the presented test reaches the sensitivity of established tests. For waste sites, a considerably higher
sensitivity was determined. An avoidance behaviour of at least 80% of the worms leaving the soil to be assessed is proposed
as a criterion for toxicity.
Background, Aims and Scope
Endpoints in earthworm ecotoxicology scheduled in guidelines are mortality and reproduction rates. However, not only the direct influence of pollutants on population parameters but also changes in behaviour such as substrate avoidance can have an important impact on soil ecosystems. In practice two different avoidance response tests are applied in earthworm ecotoxicology: (i) a six-chamber test system and (ii) a two-chamber test system. Both avoidance response-test systems were compared to establish their respective advantages and disadvantages in order to advance the standardisation of behavioural tests. The earthworm avoidance-response tests were applied in addition to the standard acute and chronic earthworm toxicity tests (ISO 11268) in order to compare the sensitivity of the test endpoints.
Methods
Test substrates were contaminated with crude oil and 2,4,6-Trinitrotoluene (TNT), respectively. The test species wasEisenia fetida. The earthworms were exposed to the contaminated substrates and their mortality (14 d), reproduction rates (number of cocoons after 28 d, juvenile hatching after 56 d), and substrate preference (48 h) determined.
Results and Discussion
Whereas 1000 mg/kg TPH (Total Petroleum Hydrocarbons) did not show any lethal effects, 100% mortality occurred in soil with comparable TNT concentration. The acute tests consistently produced the highest effect concentrations whereas reproduction and substrate avoidance were the more sensitive test parameters. Both behavioural test systems, when compared, showed similar substrate avoidance after an incubation time of 48 h. The six-chamber test system provides the potential to test six different substrates/concentrations at one time. It was observed, however, that earthworms did not migrate among all test chambers within a test unit in order to select the most appropriate substrate. Orientation was observed only between directly neighbouring test compartments, which complicates the interpretation of the test results.
Conclusion
Substrate avoidance and reproduction variables were clearly more sensitive test endpoints than mortality. Therefore avoidance-response tests proved to be useful test methods in detecting effects of sublethal concentrations of pollutants on earthworms. The test duration of the avoidance tests is much shorter compared to the standard acute and chronic earthworm toxicity tests, which makes them a quick screening tool for identifying potential soil toxicity. Both avoidance-response test systems showed comparable results regarding the test sensitivity. Nonetheless, the incomplete substrate use in the six-chamber avoidance test due to the reduced migration possibilities (orientation only to neighbouring chambers) might reduce the distinctness of test results as it allows only reliable information on the most avoided and therefore most toxic substrate but not on 1 a clear dose-response pattern. Thus, to gain valid results, the number of replicates and the arrangement of the different substrates must be adopted. The two-chamber test system is less time-consuming due to easy handling and test results can be quantified more easily.
Recommendations and Outlook
In consequence of the better validity of test results, lower expenses for test containers and less time for handling, the use of the two-chamber system is preferred over the six-chamber test system to assess the toxicity of polluted soil. Because of the ecosystem consequences of behavioural effects and the fact that avoidance response tests can reveal the toxic potential of pollutants in low concentrations, such tests should be included into ecotoxicological test protocols.
Ultramafic soils are characterized by a number of disadvantageous living conditions, especially extremely high concentrations of different metals. To evaluate the bioavailability of these metals, two ecophysiologically different earthworm species, Aporrectodea caliginosa and Eisenia fetida, were exposed for at least 14 weeks to ultramafic soils collected in the Barberton Region, Mpumalanga, South Africa (25°33′S, 30°47′E), containing extremely high concentrations of chromium, manganese and nickel with a maximum of 2894 mg Cr/kg, 1994 mg Mn/kg and 13,926 mg Ni/kg soil dry wt. In addition, a sequential fractionation evaluating the different metal phases in the soils was conducted to determine the environmental availability of selected metals. For the mobile metal fraction, easily exchangeable metals were substituted by a 0.01 mol/L CaCl2 solution. The mobilisable fraction, resembling easily remobilisable complexed and carbonated metal ions, was addressed by a DTPA extraction.
The toxicity of cholinesterase (ChE) inhibiting pesticides towards Eisenia andrei, E. fetida and E. veneta has been tested by using the standard OECD tests. The results are partly explained by in vitro and in vivo ChE inhibition patterns.Each of the three worm species had at least two cholinesterases having different bimolecular inhibition constants for all inhibitors tested.Carbaryl discriminated completely between different cholinesterases in both E. andrei and E. fetida because one of the ChEs was completely resistant, (E2); the other two (E1 a and E1b) were very sensitive, but the bimolecular constants were sufficiently different to discriminate between them.Two ChEs could be distinguished in E. veneta by carbaryl. The inhibition constants were, however, smaller than that found in the two other species.Carbaryl is known to be a strong poison for most earthworms. E. andrei and E. fetida seem to be exceptions. Therefore the use of E. veneta, which is more similar to other earthworm species, is recommended as a test organism towards cholinesterase-inhibiting pesticides for earthworms in general.
The application of refuse compost to soil for crop cultivation has become one of the most economic ways of disposal. However, injuries to existing plants or germinating crops have been frequently reported after the application of fresh compost to agricultural land. The present investigation examined the changes of phytotoxic substances of fresh refuse compost and a fresh commercial compost during storage for 115 days. During the storage period (25 ± 5°C), a portion of each type of compost was withdrawn every 30 days for glasshouse trials on Brassica parachinensis Bailey by mixing the compost with a sandy soil (at ratios of 75, 100 and 125 tonnes ha−1). Dry weights of B. parachinensis were determined after a growing period of 26 days. It was noted that the fresh compost inhibited plant growth and that production increased gradually as the compost matured, with the highest dry weights being obtained in the final test for each type of compost. Aqueous extracts were prepared every 20 days from each type of compost. These extracts were applied to seeds of B. parachinensis, and the effects on seed germination and root length of the germinated seeds were recorded. The contents of ammonia and ethylene oxide were analysed. In general, both ammonia and ethylene oxide dropped gradually towards the end of the storage period. Their contents were inversely correlated with seed germination and root elongation of B. parachinensis. It was concluded that compost from the composting plant should be stored for at least 115 days before application to crops.
The influence of various inorganic and organic fertilizers was assessed in three long-term “classical” experiments and two short-term field experiments, one on grass and one on wheat. The long-term experiments included Broadbalk which had grown continuous wheat since 1843, Barnfield, continuous root crops since 1843 and Park Grass, continuous grass since 1836. Annual fertilizer treatments were farmyard manure (48 and 96 kg N ha−1), various forms of inorganic nitrogen (48, 96, 144 and 192 kg N ha−1), liquid and solid sewage sludge and sewage cake in a wide range of doses.In the three arable experiments, all species of earthworms were more numerous in plots treated with organic fertilizers than in untreated plots.There was a strong positive correlation (r = 0.9825) between amounts of inorganic N applied and populations of earthworms. Plots receiving both inorganic and organic N had the largest populations of earthworms.The effects of both inorganic and organic N were much less on earthworm populations in grassland than on those in arable crops, even in the long-term experiments, and there was some evidence of adverse effects when an excessive amount of liquid sludge was applied in a single dose.Effects of organic fertilizers were greater on populations of Lumbricus terrestris than on those of Allolobophora longa, A. caliginosa or A. chorotica.
We studied the effect of salinity on some life-cycle parameters in the collembolan Folsomia candida, the enchytraeid Enchytraeus doerjesi, and two earthworm species, Eisenia fetida and Aporrectodea caliginosa, using natural saline soil from Robertson, Western Cape, South Africa. Specimens of the four species were exposed to soils along a gradient of salinity with electrical conductivity (EC) ranging from 0.08 to 1.62 dS m−1, under controlled laboratory conditions for 28 days. The results showed that although survival of E. doerjesi and F. candida was not significantly affected in this salinity range, juvenile production was significantly affected at 1.03 dS m−1 and higher. For E. doerjesi, absolute cessation of reproduction occurred at 1.31 dS m−1 while for F. candida, it occurred at a higher EC of 1.62 dS m−1. For E. fetida and A. caliginosa, survival was significantly affected at and above 0.92 and 1.31 dS m−1, respectively, while total mortality occurred at 1.31 and 1.62 dS m−1, respectively. Both earthworm species only produced cocoons in control soils. Growth of A. caliginosa was significantly affected at a lower EC (0.52 dS m−1) than that which affected the growth of E. fetida (1.03 dS m−1). Thus, the sensitivity of these soil organisms to saline stress, based on survival and reproduction data increased in the order: F. candida<E. doerjesi<A. caliginosa<E. fetida. Further investigation and of more taxa, may support the findings of this study that suggest that earthworms could be useful as indicators of saline disturbance than other taxa.
It is obvious that the application of solid waste compost improves the soil fertility. These wastes, however, may also have some negative effects on the agricultural environment due to their metal content. This research aimed at evaluating the influence of Tunisian municipal solid waste compost and farmyard manure on some chemical properties and the distribution of heavy metals in a calcareous Tunisian soil (clayey–loamy soil). A field plot experiment, without vegetation, was installed since 1999 at the experimental farm of the Agronomic National Institute of Tunis (INAT) in the region of Mornag (20 km south of Tunis, Tunisia). During 5 years, the field received yearly the following treatments: 0, 40, 80 and 120 t/ha of municipal solid waste compost and 0, 40 and 120 t/ha of manure. The fractionation of heavy metals in the soil was evaluated after 5 years using a sequential extraction procedure. The application of the two amendments was found to increase the content of organic matter, the total nitrogen content and the electrical conductivity, whereas it slightly decreased the soil pH. The addition of manure did not have a significant effect on the accumulation of heavy metals in the soil, whereas compost application increased the total concentration of heavy metals in the soil. The distribution of heavy metals between the different fractions in untreated and treated soils showed the residual fraction to be dominant, followed by the fraction bound to Fe and Mn oxides. The amount of Cu bound to the organic fraction increased with the application rate, which is probably caused by the formation of organic complexes. For the other metals, the increase of the association with organic matter is very limited. The application of compost moreover increases the amount of Zn associated with Fe and Mn oxides. The “Mobility Factor (MF)” was quite low and did not change after the 5-year application of the two organic amendments. It always remained lower than 10%, although for Cd it amounted to 17%.
We present the results of a plot experiment in which the changes in physical, chemical and physico-chemical properties of a sandy soil were examined after amending the soil with two different composts produced from municipal solid wastes. Triticale (X Triticosecale), cultivated in a 3-y monoculture, was used as a test plant. Both composts differed in their concentrations of heavy metals. Composts were applied non-recurrently in the spring before sowing, at the rates of 18, 36, and 72 t dry matter ha−1. The plots without fertilization, and those fertilized annually with mineral nitrogen (N), phosphorous (P), and potassium (K) were used as controls. Soil samples were collected 1 month after compost application, as well as each year after harvesting. Application of both composts improved soil physical properties, associated with increasing content of organic carbon (OC). Statistically significant increases of total porosity, field water capacity and amounts of plant-available water were found only in the short time after compost application. Despite the fact that soil OC content decreased with time, a C:N ratio clearly increased in the third year after compost application, which was explained by a depletion of N reserve. Both composts caused a large increase of plant-available P, K, and magnesium (Mg), which was observed during the entire period of the experiment. Beneficial changes were also observed in soil humic substances composition. These were confirmed by increased humic acids content and humic/fulvic acid ratios. Soil cation exchange capacity and base saturation increased in all plots amended with composts. This effect was still observed 1 year after compost application, while in the third year it remained significant only at the highest compost rates. Compost originating from industrial areas, even if applied in low amounts, caused a significant increase in total concentration of soil heavy metals. This fact did not result, however, in any substantial changes in soil quality with regard to heavy metals content.
The metal (Cd, Cu, Pb, Zn and Ca) concentrations in the tissues, ingesta (crop contents) and egesta (faeces) were investigated in two physiologically contrasting earthworm species (Lumbricus rubellus and Aporrectodea caliginosa) inhabiting soils exhibiting various levels of heavy metal contamination. In addition, a complementary soil layering experiment, conducted under laboratory conditions, was undertaken to investigate whether the distribution of Pb within a soil vertical profile influenced the relative metal accumulation patterns of these species. Generally, the Cd, Cu and Pb concentrations of field populations of A. caliginosa were significantly greater than in L. rubellus, a pattern reversed for Ca. Concentrations of Zn were significantly greater in A. caliginosa in soils containing the lowest Zn concentrations, but no species differences were apparent at high soil concentrations of this metal. Comparisons of metal concentrations between ingesta and soils indicate that both species selectively ingest material from the soil matrix, although no significant correlations were found between tissue metal and ingesta metal concentrations. Differences in concentrations of Cd, Pb and Zn between the ingesta of the species were, however, concomitant with observed differences in tissue concentrations of the respective metals, which cannot be explained by excretion via the egesta. The soil stratification experiment indicated that Pb distribution within a soil profile affected the pattern of species differences in tissue metal concentrations observed in field populations. The evidence therefore suggests that the difference in dietary intakes of these metals is an important factor in contributing to observed differences between these species, although other factors are also contributory. The observations are discussed in the context of soil hazard assessment monitoring, and in particular, the role of concentration factors in such applied surveys.
At present, standardised earthworm acute toxicity and reproduction tests are used to assess the toxicity of heavy metal contaminated soils. These tests are, however, time-consuming, laborious and costly, and in addition, some sublethal responses may remain overlooked. Avoidance of metal contaminated soils by earthworms may be a useful parameter when assessing ecological risks with a low test effort. The objective of the present study was to find out whether the earthworm Aporrectodea tuberculata avoids soils simultaneously contaminated with Cu and Zn, and whether earlier exposure to metal-polluted soil affects its avoidance response. The aim was also to compare the sensitivity of the earthworm avoidance test to the standardised acute toxicity and reproduction tests. A. tuberculata clearly avoided lower soil metal concentrations than those that induced responses in the acute toxicity and reproduction tests. The standard species in the earthworm tests, Eisenia fetida, appeared to be more tolerant to metals and it seemed to regulate the tissue metal concentrations more strictly than A. tuberculata. The majority of the test parameters measured for A. tuberculata showed that earthworms of the population with long-term exposure history in metal-polluted soil responded at higher soil metal concentrations than earthworms of the population without earlier exposure to metal-polluted soil. Thus, the earthworms living in the metal contaminated area were either better adapted or acclimatized to live in metal contaminated soil. It was concluded that an earthworm test battery including avoidance, acute toxicity and reproduction tests can be an efficient tool in assessing ecological risks of contaminated soils. However, careful choice of the test species and even populations within the species is recommended.
Endogeic earthworms play an important role in mobilisation and stabilisation of carbon and nitrogen in forest and arable soils. Soil organic matter is the major food resource for endogeic earthworms, but little is known about the size and origin of the organic matter pool on which the earthworms actually live. We measured changes in body mass of juvenile endogeic earthworms, Octolasion tyrtaeum (Savigny), in soils with different C and N contents resulting from different fertiliser treatments. The soil was taken from a long-term experiment (Statischer Düngungsversuch, Bad Lauchstädt, Germany). The treatments included (1) non-fertilised soil, (2) NPK fertilised soil, (3) farmyard manure fertilised soil and (4) NPK + farmyard manure fertilised soil. The soil was incubated in microcosms with and without one juvenile O. tyrtaeum for 80 days.
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Contact bioassays are important for testing the ecotoxicity of solid materials. However, survival and reproduction tests are often not practical due to their duration which may last for several weeks. Avoidance tests with soil invertebrates may offer an alternative or extension to the classic test batteries due to their short duration (days rather than weeks) and due to a sensitive sub-acute endpoint (behavior).
The aims of our study were:
(a) to evaluate the effects of three solid industrial wastes (incineration ash, contaminated wood chips and contaminated soil) on three Oligochaeta species (enchytraeids Enchytraeusalbidus, Enchytraeus crypticus and earthworm Eisenia fetida) in avoidance tests; (b) to compare the sensitivity among the species and to compare results of avoidance test to reproduction tests; (c) to elucidate if measuring the weight in the earthworm avoidance test could be reasonable additional endpoint. Avoidance mostly increased with the increasing percent of waste in the mixture showing a dose-response curve. E. fetida was the most sensitive species and E. crypticus the least one. An additional endpoint, (changes in weight after two-day exposure) was not found to be more sensitive than avoidance reaction, but it confirmed that earthworms staying in the highest concentrations of the waste mixture were affected showing apparent weight reduction. Our results indicate that avoidance tests with earthworms and enchytraeids are feasible for waste testing.
We studied the avoidance behaviour of Eisenia fetida and Aporrectodea caliginosa in OECD artificial soil spiked with NaCl and in natural saline soil (of varying ionic constitutions) collected from Robertson Experimental Farm (ROBS) in Western Cape, South Africa. For each organism, the ecotoxicological test was performed using a two-chamber test over a period of 48 h. The results showed that in the OECD soil, the avoidance EC50 (the concentration/electrical conductivity at which there is effect on 50% of the organisms) for A. caliginosa of 667 mg kg(-1) NaCl was lower than 1164 mg kg(-1) for E. fetida. Similarly in ROBS soil, the avoidance EC50 for A. caliginosa of 0.26 dS m(-1) was lower than 0.56 dS m(-1) in E. fetida. These results indicated that A. caliginosa showed better avoidance to salinity than E. fetida irrespective of soil types or ionic constitution. When compared with literature data, EC50 values in avoidance tests were either lower or comparable to those of reproduction, which was the most sensitive life-cycle parameter. The only exception was the EC50 value for avoidance of E. fetida in natural soil which was higher than for reproduction suggesting that the predictive value of the avoidance test for this species might be lower in natural soils. The variation in sensitivities of these earthworms could be as a result of differences in their eco-physiology. These findings suggest the relevance of the avoidance test as a suitable screening method showing first tendencies of saline stress on the habitat function of soils.
Juvenile Eisenia fetida (Savigny) were exposed for 20 weeks to an uncontaminated soil and to soils contaminated with cadmium, copper, lead, and zinc collected from seven sites at different distances from a smelting works at Avonmouth, southwest England. The survival, growth (= weight after 5 weeks exposure), time to sexual maturation (= percentages of adults present after 8 weeks), and reproduction (= number of cocoons produced by the worms) were compared with soil metal concentrations. Of the parameters measured, growth and sexual maturation time had the lowest EC50 values. The effects of metal-contaminated soils could be attributed both to the direct toxicity of the metals and to changes in the "scope for growth" of the exposed worms. A comparison of the results with those of an earlier toxicity test conducted with adult worms indicated that juveniles are more sensitive to metals than adults. Significant toxic effects on the growth and sexual maturation times of juveniles were detected in soils from sites for which no significant effects on the cocoon production of adults could be detected. The greater sensitivity of juvenile worms indicates the importance of considering effects on a variety of life history stages when conducting a risk assessment of the effects of pollutants in soils. Although E. fetida does not occur naturally in soils at Avonmouth, the present study provides evidence to support the suggestion that pollution from the smelter is responsible for the absence of worms within 2 km of the factory. Results presented in this paper, and from previous studies, suggest the observed absence is due to the effects of zinc on the growth and maturation of juveniles and the cocoon production rate of adult worms.
Bio-waste recycling and the production and use of bio-compost are politically encouraged in Europe. Quality control takes no consideration of pathogenic anaerobic spore formers, e.g. Clostridium botulinum. A protocol for health hazard analysis concerning this pathogen has been developed. Samples of marketed bio-compost were tested and results showed that about 50% of the tested samples contained C. botulinum. For the first time it has been shown that the use of bio-compost represents a health hazard to humans and animals, especially in the future when spores will have accumulated in the environment. The use of household bio-waste collected in 'bio-bins' is apparently one factor involved in the production of contaminated compost end-products. Environmental factors in the propagation of C. botulinum are discussed. The improvement of bio-waste recycling technology and management should be encouraged in order to minimize the health hazard caused by contaminated bio-compost.
Interest in the ecological effects of composting has been growing recently. However, no established methods are available for testing the toxicity of composted materials. Despite this, international and national quality requirements define that compost shall not contain any environmentally harmful substances. Safety requirements have to be fulfilled if the produced compost is intended for agricultural use. This literature review focuses on methods that could potentially be used to evaluate the ecotoxicity of compost. The toxicity test methods discussed are those employing microbes, enzymes, soil fauna, and plants.
Three biomarkers in Aporrectodea caliginosa Savigny were evaluated for their ability to detect exposure to organophosphorus insecticides, and these physiological responses were related to effects on growth and life-table parameters. Adult and juvenile earthworms were exposed to a laboratory-simulated field rate (low concentration) and a higher sublethal concentration of diazinon and chlorpyrifos. After a four-week exposure, juveniles were evaluated for cholinesterase activity, glutathione S-transferase activity, and growth, and adults were evaluated for the lysosomal neutral red retention assay (NRRA) and growth. Cholinesterase activity and the NRRA were more sensitive than growth in each age group for detecting exposure to the pesticides. Life-table parameters were evaluated in earthworms exposed as juveniles and as adults. Maturation was less sensitive to pesticides than was cocoon production. Growth and cocoon production in earthworms exposed as juveniles appeared to be more sensitive to organophosphorus insecticides than earthworms exposed as adults. Life-table responses in juveniles may, therefore, be more predictive of long-term impacts of organophosphorus insecticide applications on populations than responses in adults. Biomarker responses occurred at similar or lower concentrations than those causing an adverse effect on cocoon production and cocoon viability, indicating their usefulness in risk assessment for predicting ecologically relevant assessment end points.
The biodegradability of lactic acid based polymers was studied under controlled composting conditions (CEN prEN 14046), and the quality of the compost was evaluated. Poly(lactic acids), poly(ester-urethanes), and poly(ester-amide) were synthesized and the effects of different structure units were investigated. The ecotoxicological impact of compost samples was evaluated by biotests, i.e., by the Flash test, measuring the inhibition of light production of Vibrio fischeri, and by plant growth tests with cress, radish, and barley. All the polymers biodegraded to over 90% of the positive control in 6 months, which is the limit set by the CEN standard. Toxicity was detected in poly(ester-urethane) samples where chain linking of lactic acid oligomers had been carried out with 1,6-hexamethylene diisocyanate (HMDI). Both the Flash test and the plant growth tests indicated equal response to initial HMDI concentration in the polymer. All other polymers, including poly(ester-urethane) chain linked with 1,4-butane diisocyanate, showed no toxicological effect.