Technical Recommendations for the Update of the ISO Earthworm Field Test Guideline (ISO 11268-3) (5 pp)

Background, Aim and Scope   Background, Aims and Scope. The earthworm field test firstly was developed by the German Federal Biological Research Centre for Agriculture and Forestry (BBA) for testing of pesticides and later internationally standardised by the International Organization for Standardization (ISO) as a tool for characterizing soil quality. It is mainly used for the assessment of effects of pesticides on earthworms under field conditions. Growing experience has shown that the practical performance of the test can be improved. Main Features: In two meetings organised by the Federal Biological Research Centre for Agriculture and Forestry (Braunschweig, 2002) and later the German Federal Agency for Consumer Protection and Food Safety (Lille, 2005) an ad-hoc working group of experts from various countries and institutions discussed the practical performance and recommendations that should be taken into account in a revised draft following the current ISO guideline after the proposed revision has been approved by voting in the periodical review. Results: The outcome of the discussions and the background of the recommendations of the ad-hoc working group are briefly summarised in this paper. These are mainly methodological details in order to improve the test performance (e.g. by decreasing variability or increasing practicability). Discussion: These recommendations are proposed to be considered for the next update of the current ISO guideline. They should be seen as technical amendments still waiting for their approval by standardisation organisations. Conclusions: Although this method focuses on the assessment of effects of pesticides on earthworms, the recommendations will also be valuable for testing contaminated soils. The recommendations presented may also be a first step for splitting the current guideline into two fields of application, one for testing of chemicals and pesticides (i.e. within the scope of OECD) and another one for testing soil quality (i.e. within the scope of ISO). Perspectives: Nevertheless, there is still a major need for guidance concerning the interpretation of effects determined in such complex field tests.     

Influence of soil pH on the toxicity of aluminium for Eisenia andrei (Oligochaeta: Lumbricidae) in an artificial soil substrate

Toxicity of aluminium for the earthworm Eisenia andrei was studied in artificial soil at different pH levels. In a range-finding test, effects of three different aluminium salts on earthworm survival were determined. AlCl₃ appeared to be most toxic, with LC₅₀ values of 316, 359 and >1000 mg Al/kg dry soil at pH_KCl of 3.5, 4.4 and 6.7, respectively in the control soils. Effects of this salt interfered with a strong decrease of soil pH with increasing aluminium concentration. Al₂(SO₄)₃ was less toxic with LC₅₀ values of 457, >4000 and >4000 mg Al/kg dry soil at pH 3.24, 4.86 and 7.22, respectively. Al₂O₃ did not affect earthworm survival at concentrations of 5000 mg Al/kg and pH levels between 2.4 and 7.1.In the main test, earthworms were exposed for 6 weeks to soils treated with Al₂(SO₄)₃. As in the range-finding test, aluminium sulfate was most toxic at a pH of 3.4 with an LC₅₀ of 589 mg Al/kg dry soil. At this pH, growth and cocoon production of earthworms were significantly reduced at 320 mg Al/kg dry soil, while at 1000 mg Al/kg dry soil all earthworms died. Survival was not affected by 1000 mg Al/kg dry soil at pH 4.3 and 7.3. At pH 4.3, growth was significantly reduced at 1000 mg Al/kg dry soil and cocoon production at 320 and 1000 mg Al/kg dry soil. At pH 7.3, aluminium only affected cocoon production at the two highest exposure levels. At the highest two exposure levels at pH 7.3, growth was significantly increased, suggesting a trade-off between growth and reproduction. These effects of aluminium at the highest soil pH could not be explained from the concentration of extractable, monomeric (labile) aluminium in soil, which decreased with increasing soil pH.     

Effects-based Assays in the Earthworm Aporrectodea caliginosa: Their Utilisation for Evaluation of Contaminated Sites before and after Remediation (8 pp)

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.     

外源有机酸对蚯蚓Zn积累的影响及毒性研究

为研究外源有机酸是否会增加土壤动物蚯蚓对重金属的吸收,从而加剧重金属对土壤生态系统的危害,采用溶液法,以锌为目标污染物,研究添加有机酸(乙酸、草酸、柠檬酸和EDTA)后,重金属对蚯蚓的毒害效应。结果表明,有机酸能有效缓解Zn对蚯蚓的毒性,缓解强弱顺序为EDTA柠檬酸草酸乙酸,主要表现为蚯蚓死亡率降低。暴露在Zn浓度为5,10,15 mg/L的溶液中时,死亡率分别为20%,55%,83.75%,随着有机酸浓度增加,蚯蚓死亡率下降越显著;抗氧化酶(SOD、CAT)和丙二醛(MDA)含量下降,不同的有机酸对蚯蚓SOD、CAT活性的影响不一,MDA含量则有明显的下降趋势,甚至接近于对照水平。这主要是由于有机酸抑制了蚯蚓对Zn的富集,有机酸的络合作用改变了Zn的亚细胞分布,E(胞残渣)组分的比例下降,而H(热稳定组分)组分上升,从而降低了重金属所引起的毒害。因此,有机酸在控制重金属的生物可利用性方面具有重要作用。     

An investigation of the impact of Glomus clarum (mycorrhiza) on the growth of tomato (Lycopersicum esculentum mill.) on both sterilized and non-sterilized soils

Abstract

A greenhouse experiment was carried out to investigate the influence of Glomus clarum (mycorrhiza) on the growth of tomato seedlings grown in both sterilized and non-sterilized soils. Highest growth parameter values were recorded in tomato plants inoculated with mycorrhiza but grown in sterilized soil, followed by those grown in non-sterilized soil but inoculated with mycorrhiza also. Sterilized but non-inoculated tomato plants also had growth and were closely followed by non-sterilized, non-inoculated tomato plants. There was no significant difference in all the treatments when girth of the tomato plants used was measured in this study. Nutrient uptake (N,P,K) was significantly found highest in the inoculated sterilized tomato plants while it was found lowest in the non-sterilized, non-inoculated tomato plants. Generally, mycorrhizal-inoculated tomato plants (whether sterilized or non-sterilized) showed better growth in all the treatments used.