From the importance of organic carbon in reproduction tests with Eisenia fetida

The standard Eisenia fetida chronic toxicity reproduction test is normalized and needs up to 8 weeks of experimentation. Many matrixes have shown toxic effects on the earthworms' survey, growth and reproduction. But the food factor may affect the organisms' responses to contaminated media in such tests. We try to evaluate the effect, or not, of the organic carbon content present in the environment, as spreadable organic wastes added in soil, on the reproduction test of Eisenia fetida. We confirm the influence of the organic matter content on earthworm reproduction. This "food" factor must be considered when studying environmental samples rich in organic matter, since that could mask potentially harmful effects. To minimize this potential "food" effect during reproduction tests, we recommend an inverse gradient of organic matter contribution by the "horse dung" food applied in all conditions according to the dose of agricultural amendments tested.

Influence of edaphic conditions and persistent organic pollutants on earthworms in an infiltration basin

In recent decades, stormwater management has developed to allow stormwater to infiltrate directly into the soils instead of being collected and routed to sewer systems. However, during infiltration, stormwater creates a sediment deposit at the soil surface as the result of high loads of suspended particles (including pollutants), leading to the settlement of sedimentary layers prone to colonization by plants and earthworms. This study aims to investigate the earthworm communities of a peculiar infiltration basin and investigate the influence of edaphic conditions (water content, organic matter content, pH, height of sediment) and of persistent organic pollutants (POPs: PCBs, PCDDs and PCDFs) on these earthworms. Attention was paid to their age (juveniles or adults) and their functional group (epigeic, endogeic, anecic). We found that the earthworm abundance was mostly driven by edaphic conditions, with only a slight impact of POPs, with a significant negative impact of PCBDLno for juveniles and endogeic, and PCDDs for epigeic. On the contrary, the height of the sediment and the water content are beneficial for their presence and reproduction. Furthermore, POPs contents are also linked to physicochemical parameters of the sediment. Bioaccumulation was clearly revealed in the studied site but does not differ between juveniles and adults, except for PCDDs. Conversely, BAF values seemed to vary between functional groups, except for PCBDL non-ortho. It strongly varies with the family types (PCBs versus PCCD/Fs) and between congeners within the same family, with specific strong bioaccumulation for a few congeners.

Bioavailability and bioaccumulation of heavy metals of several soils and sediments (from industrialized urban areas) for Eisenia fetida

Soils and sediments are susceptible to anthropogenic contamination with Metallic Trace Elements (MTEs) and it can present some risks to ecosystems and human health. The levels of Cd, Cu, Fe, Ni, Pb and Zn were assessed in soils (C, G, K, L) from Estarreja (Portugal) and sediments from a stormwater basin in Lyon (DJG), a harbour (LDB) and a Rhône river site (TRS) (France). An ecotoxicological study was performed with Eisenia fetida (E. fetida) to infer about potential transfer risks to the soil invertebrates. To assess risks associated with MTEs contamination, it is important to know their total concentrations, fractionation and the potential available fractions. CaCl₂, DTPA and NaOAc extractions were performed to assess the extractable and available MTEs fractions. The studied sediments were much more contaminated than the soils for all the MTEs analysed. The trace elements fraction linked with DTPA extraction shows higher values when compared with the NaOAc and the CaCl₂ pools. Low mortality effects were recorded in the tests with E. fetida. The MTEs levels in soils and sediments and the concentrations bioaccumulated in adult earthworms contributed to a reduction in the number of juveniles produced. E. fetida adults and juveniles accumulated ETMs as follows: Cd > Cu = Zn > Ni > Pb > Fe. Determined BAFs were mostly lower than 1 with some higher values for Cd, Cu and Zn. Calculated SET and ERITME indexes allowed to classify the samples from the most to the less toxic for E. fetida as: LDB > DJG > L > G > C > K > TRS. Despite this order of toxicity, the earthworms exposed to the sediment TRS presented the lowest reproduction rate. The combination of "chemical" measurements with the calculation of BAFs, but especially SET and ERITME indexes can be a useful tool in risk assessment.

Evaluation of phytotoxicity of seaport sediments aged artificially by rotary leaching in the framework of a quarry deposit scenario

In the framework of an ecological risk assessment of seaport sediments for terrestrial ecosystems when deposited in quarries, we simulated the "ageing" of sediments exposed to rain. This experiment highlighted an inflection point at the solid/liquid ratio 1/25, after which the extraction of pollutants increases moderately. The raw sediments studied inhibited the germination of Lolium perenne and Armeria maritima (a halophytic species) seeds. Furthermore, they affected the early development of L.perenne. The same sediments, leached at a ratio of 1/25, presented a reduction of acute (germination) and chronic (growth) phytotoxicity. The bioconcentration factors of the metals studied decreased with the leached sediment, except for Cu which was still clearly identified in root parts. Thus rotary leaching tests and phytotoxicity bioassays can be used to provide an initial assessment of the ability of plants, particularly halophytes, to colonize deposits of dredged seaport sediments.

Selection of a halophytic plant for assessing the phytotoxicity of dredged seaport sediment stored on land

The filling of dry quarries in coastal areas with sediments dredged in seaports represents a potentially interesting method of recycling of these materials. However, this recycling requires the prior carrying out of an Environmental Risk Assessment of the scenario concerned. For this, the question arose as to the type of plants capable of developing on the surface of such a deposit and the method to implement for assessing the possible phytotoxicity of dredged sediments. To answer this question, we chose to work with halophytic plants to be free from the salt-related effect and to assess only the effect related to the toxic compounds present. Based on the objectives set, these works led to the use of common plants of the French coast, with direct seeding, and with pollution-sensitive plants. Three species of angiosperms, Armeria maritima, Anthemis maritima and Plantago coronopus, were finally tested. As a result of this work, Armeria maritima was retained as the most suitable plant for testing the possible phytotoxic effect of dredged marine sediments stored on land. The results obtained with this plant are as follows: germination of 40 % of the seeds in 31 days, produced biomass of 493 mg FW in 6 months and a capacity to bioaccumulate metal pollutants in roots with 350 and 720 mg/kg DW for Zn and Cu, respectively.

Assessment of the phytotoxicity of seaport sediments in the framework of a quarry-deposit scenario: germination tests of sediments aged artificially by column leaching

The aim of the Sustainable Management of Sediments Dredged in Seaports (SEDIGEST) project is to assess the risks of treated port sediments for terrestrial ecosystems when deposited in quarries. We simulated the "ageing" of these sediments up to the "moment" when plants can germinate. Sediments were leached by water percolating through a laboratory column. Sediments 1 and 2, taken from the port of Toulon (France), were dried and aired. Sediment 3, taken from the port of Guilvinec (France), was stabilised with lime. Phytotoxicity was evaluated on the three artificially aged sediments using germination and early development tests (48 h to 7 days) by Phytotoxkit F(TM) bioassays. The three dilutions tested were performed with the reference "ISO substrate" and with Lolium perenne sp. (rye grass), Sinapis alba (white mustard), and Lepidium sativum (watercress). The tests performed with sediments 1 and 2 showed (1) a decrease of their toxicity to the germination of the species selected following leaching and (2) that L. perenne was the most sensitive species. The tests performed with sediment 3 showed that it was improper for colonisation even after leaching simulating 16 months of ageing. These germination tests on aged sediments identified the effects of leaching and made it possible to appreciate the capacity of the sediments to allow colonisation by plants.

Influences on the establishment and dominance of vegetation in stormwater infiltration basins

Infiltration basins are widely used in urban environments as a technique for managing and reducing the volume of stormwater. These basins can be spontaneously colonized by wild plants, which can be used as bioindicators of edaphic characteristics. As the basins are anthropogenic environments, the description of plant biodiversity allows the determination of which species colonize such environments and identification of the relationships between plants, basin type and operation. Nineteen infiltration basins were selected according to their catchment types (industrial, urban, agricultural). The dominant species were identified and sampled. Rumex sp., Taraxacum sp. and Artemisia sp. are the three types most represented (88, 61 and 55% respectively of the basins studied). Their families and their respective orders are those most commonly found (Caryophyllales, Asterales and Polygonaceae, Asteraceae). Poaceae is the family grouping with the largest number of different species (11). Although each species occupies only 1 or 2 basins, plants of this family occupy 61% of the basins. Although the catchment characteristics of the 19 basins do not play a direct role in the diversity of plant families, they can influence the presence or absence of certain species. Thus, these plants can be used as bio-indicators of basin soil and operating characteristics, such as sediment depths, inundation frequency and duration.

Polymorphism in morels: isozyme electrophoretic analysis

The aim of this study was to assess whether isozyme polymorphism in different members of the Morchellaceae could be used to improve the systematics in this fungal group and to characterize intraspecific crossings between monosporal strains in Morchella esculenta. For this purpose, isozyme electrophoretic analysis of the following enzymes was performed: glutamine synthetase, NAD-glutamate dehydrogenase, NADP-glutamate dehydrogenase, aspartate aminotransferase, malate dehydrogenase, NAD-glyceraldehyde phosphate dehydrogenase, glucose phosphate isomerase, and superoxide dismutase. The analyses allowed discrimination at the inter- or intra-specific levels and could help to establish a method of identification for strains in the Morchellaceae. To a certain extent they appeared to be suitable to analyze interactions of monosporal strains of Morchella esculenta in pairing experiments. The polymorphism shown in this study was consistent with the phylogenetic relationships between the investigated strains only at the genus level.Key words: isozyme analysis, electrophoresis, Morchella sp., polymorphism.

Cd, Cu and Zn mobility in contaminated sediments from an infiltration basin colonized by wild plants: the case of Phalaris arundinacea and Typha latifolia

Infiltration basins are shallow reservoirs in which stormwater is temporarily collected in order to reduce water volume in downstream networks. The settling of stormwater particles leads to a contaminated sediment layer. Wild plants can colonize these basins and can also play a role on the fate of heavy metals either directly by their uptake or indirectly by modification of physico-chemical characteristics of the sediment and therefore by modification of the mobility of heavy metals. The aim of this study, carried out in a vegetated infiltration basin, is to assess Cd, Cu and Zn mobility in two zones colonized by different species, Phalaris arundinacea and Typha latifolia. The study was carried out using three single chemical extractions: CaCl2 for the exchangeable phase, acetate buffer for the acido-soluble fraction and diethylenetriamine-pentaacetic acid (DTPA) for the fraction associated to the organic matter. Zn and Cd are mainly associated to carbonated and organic matter phases of the sediment. Moreover, acetate buffer-extractable Zn contents are strongly correlated to carbonates content in the sediment. DTPA-extractable Cu contents are strongly correlated with organic carbon sediment contents. We have also noted that extractable contents were significantly different between both zones whatever the metal.

Benefits and limits of sediment toxicity tests as an aid to decision-making

With respect to the management of dredged sediments, a crucial issue is whether the removed materials (watered and/or processed) are disposed of or reused in an environmentally sound manner. In this context, the number of studies dealing with hazard or risk assessment has exponentially increased. This emphasis has resulted in the promotion and application of a very large variety of ecotoxicological tests. As a consequence, there is a clear need to highlight the scope and limitations of these tests for their appropriate selection and interpretation. In this paper we discuss the choice, implementation and interpretation of laboratory tests carried out on aquatic organisms at various levels of biological organization. We examine some experimental tools and methods in order to determine how suitable they are in regard to the objectives for which they are employed. To make this discussion more consistent our paper is based on results from research programmes conducted for governmental organizations and industrial partners. The Laboratoire des Sciences de l'Environnement (LSE) was involved with Cemagref de Lyon in a first methodological programme on risk assessment of scenarios of dredged sediment deposition. Another programme for a chemical company was implemented to assess the benefits of a physico-chemical treatment applied to contaminated dredged sediments in a scenario of reuse or deposit in gravel pits. Currently, the LSE is working on a programme of risk assessment for road sediments in valorization scenarios. From these programmes, we expose how single-species tests, as well as more complex bioassays and microcosm tests, can be used in an iterative step of risk assessment. Concerning microcosm tests, we also introduce a more realistic system that has been designed to simulate natural hydraulic conditions of gravel pits to assess the effects of toxicants on gravel pit aquatic biota during the sediment immersion phase and the sediment post-deposition phase (paper in preparation). The benefits of these ecotoxicological approaches are underlined, but limits are discussed with regard to several criteria: ecological relevance, realism, use for decision-making, cost and complexity of methods involved.