International audience | 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.

International audience | 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.

International audience | Assessment of wildlife exposure to organophosphorus (OP) pesticides generally involves the measurement of cholinesterase (ChE) inhibition, and complementary biomarkers (or related endpoints) are rarely included. Herein, we investigated the time course inhibition and recovery of ChE and carboxylesterase (CE) activities in the earthworm Lumbricus terrestris exposed to chlorpyrifos, and the ability of oximes to reactivate the phosphorylated ChE activity. Results indicated that these esterase activities are a suitable multibiomarker scheme for monitoring OP exposure due to their high sensitivity to OP inhibition and slow recovery to full activity levels following pesticide exposure. Moreover, oximes reactivated the inhibited ChE activity of the earthworms exposed to 12 and 48 mg kg−1 chlorpyrifos during the first week following pesticide exposure. This methodology is useful for providing evidence for OP-mediated ChE inhibition in individuals with a short history of OP exposure (≤1 week); resulting a valuable approach for assessing multiple OP exposure episodes in the field. Esterase inhibition combined with oxime reactivation methods is a suitable approach for monitoring organophosphate contamination

International audience | We assessed the state of knowledge regarding the effects of large-scale pollution with neonicotinoid insecticides and fipronil on non-target invertebrate species of terrestrial, freshwater and marine environments. A large section of the assessment is dedicated to the state of knowledge on sublethal effects on honeybees (<em>Apis mellifera</em>) because this important pollinator is the most studied non-target invertebrate species. Lepidoptera (butterflies and moths), Lumbricidae (earthworms), Apoidae sensu lato (bumblebees, solitary bees) and the section “other invertebrates” review available studies on the other terrestrial species. The sections on freshwater and marine species are rather short as little is known so far about the impact of neonicotinoid insecticides and fipronil on the diverse invertebrate fauna of these widely exposed habitats. For terrestrial and aquatic invertebrate species, the known effects of neonicotinoid pesticides and fipronil are described ranging from organismal toxicology and behavioural effects to population-level effects. For earthworms, freshwater and marine species, the relation of findings to regulatory risk assessment is described. Neonicotinoid insecticides exhibit very high toxicity to a wide range of invertebrates, particularly insects, and field-realistic exposure is likely to result in both lethal and a broad range of important sublethal impacts. There is a major knowledge gap regarding impacts on the grand majority of invertebrates, many of which perform essential roles enabling healthy ecosystem functioning. The data on the few non-target species on which field tests have been performed are limited by major flaws in the outdated test protocols. Despite large knowledge gaps and uncertainties, enough knowledge exists to conclude that existing levels of pollution with neonicotinoids and fipronil resulting from presently authorized uses frequently exceed the lowest observed adverse effect concentrations and are thus likely to have large-scale and wide ranging negative biological and ecological impacts on a wide range of non-target invertebrates in terrestrial, aquatic, marine and benthic habitats.

Although microplastics (MPs) are ubiquitous in agricultural soil, little is known about the effects of MPs combined with pesticides on soil organisms and their biogenic transport through the soil profile. In this study, we conducted mesocosm experiments to observe the effects of microplastics (polyethylene (LDPE-MPs) and biodegradable microplastics (Bio-MPs)) and chlorpyrifos (CPF) on earthworm (Lumbricus terrestris) mortality, growth and reproduction, as well as the biogenic transport of these contaminants through earthworm burrows. The results showed that earthworm reproduction was not affected by any treatment, but earthworm weight was reduced by 17.6% and the mortality increased by 62.5% in treatments with 28% Bio-MPs. Treatments with 28% LDPE-MPs and 7% Bio-MPs combined with CPF showed greater toxicity while the treatment with 28% Bio-MPs combined with CPF showed less toxicity on earthworm growth as compared to treatments with only MPs. The treatments with 1250 g ha−1 CPF and 28% Bio-MPs significantly decreased the bioaccumulation of CPF in earthworm bodies (1.1 ± 0.2%, w w−1), compared to the treatment with CPF alone (1.7 ± 0.4%). With CPF addition, more LDPE-MPs (8%) were transported into earthworm burrows and the distribution rate of LDPE-MPs in deeper soil was increased. No effect was observed on the transport of Bio-MPs. More CPF was transported into soil in the treatments with LDPE-MPs and Bio-MPs, 5% and 10% of added CPF, respectively. In addition, a lower level of the CPF metabolite 3,5,6-trichloropyridinol was detected in soil samples from the treatments with MPs additions than without MP additions, indicating that the presence of MPs inhibited CPF degradation. In conclusion, Bio-MPs caused significant toxicity effects on earthworms and the different types of MPs combined with CPF affected earthworms differently, and their transport along the soil profile. Thus, further research is urgently needed to understand the environmental risks of MPs and MP-associated compounds in the soil ecosystem.

Toxicokinetic (TK) model provides a new approach to mechanistically elucidate the natural variation of metal handling strategy by adaptive and sensitive earthworm populations. Here, TK model was applied to explore the metal handling and resistance strategy of wild Metaphire californica with different historical exposure history through a 12-day re-exposure and another 12-day elimination incubation. M. californica populations showed different kinetic strategies for non-essential metals (Cd and Pb) and essential metals (Zn and Cu), which were closely related to their exposure history. M. californica from the most serious Cd-contaminated soil showed the fastest kinetic rates of both Cd uptake (K₁ = 0.78 gₛₒᵢₗ/gwₒᵣₘ/day) and elimination (K₂ = 0.23 day⁻¹), and also had the lowest Cd half-life (t₁/₂ = 3.01 day), which demonstrated the potential Cd-resistance of wild M. californica from Cd-contaminated soils. Besides, the comparative experiment showed totally different metal kinetics of laboratory Eisenia fetida from field M. californica, suggesting the impacts of distinct exposure history and species-specifical sensitivities. These findings provide a novel approach to identify and quantify resistance using TK model and also imply the risk of overlooking existing exposure background and interspecies extrapolation in eco-toxicological studies and risk assessments.

Selenium (Se) is an essential micronutrient for animals with a narrow margin between essentiality and toxicity. Se toxicity is largely related to inorganic forms of Se in soil, i.e., selenite and selenate that enter food chains through plant uptake, threatening higher trophic level organisms. This experiment investigated effects of earthworm activity on Se bioavailability in soil and the subsequent plant uptake, using earthworm Eisenia fetida and bean plant Phaseolus vulgaris L, both exposed to either selenite or selenate at 1 or 4 mg Se kg⁻¹ for 16 weeks. Plants took up selenate (up to 221-fold) faster than selenite, with up to 84% of the Se rapidly transported to shoots. In the presence of earthworms, Se accumulation obviously increased for selenate-supplied plants, leading to an up to 4% increase in Se translocation factor for all treatments except for 1 mg kg⁻¹ selenite treatment. Earthworms also concentrated Se faster in tissues (up to 274 mg kg⁻¹ DW) at exposure to selenate. For Se toxicity, Se speciation analysis was conducted on the plants and earthworms using XAS. Compared to worm-free treatments, the percentage of organo-Se, i.e., SeMet and CysSeSeCys, increased in beans (up to 34%) in the presence of earthworms for selenate, while the elemental Se portion was significantly reduced or absent, opposite to the results for selenite. Surprisingly, elemental Se (up to 65%) dominated earthworms, regardless of the form of Se supplied. In conclusion, earthworms clearly enhanced Se uptake and translocation in plants, leading to elevated Se levels in shoots. To prevent resulting hazards to humans and other animals, caution should be taken while consuming the shoots, particularly beans, harvested from the Se contaminated soil where earthworm activity is high. Finally, the significant reduction in soil Se suggests phytoextraction of Se from the soil could be improved using earthworms as an aid to plants.

The remediation of cadmium (Cd) contaminated soil has become a global problem due to its toxicity to living organisms. In this study, earthworm (Eisenia fetida) alone or combined with EDTA or bean dregs were used for Cd removal from soils. The total and available Cd in soils, soil physicochemical and biological (soil enzyme) properties, Cd accumulation in the earthworm and its antioxidant responses towards Cd, were determined during the 35 days of soil incubation experiment. Our results showed that earthworms were capable of removing Cd from soils, and the remediation process was accelerated by both EDTA and bean dregs. By translocation of Cd from soils, the content of Cd in earthworm steadily increased with the exposure time to 8.11, 12.80, and 9.26 mg kg⁻¹ on day 35 for T2 (earthworm alone), T3 (EDTA enhancement), and T4 (bean dregs enhancement), respectively. Consequently, a great reduction in the Cd contents in soils was achieved in T3 (36.53%) and T4 (30.8%) compared with T2 (28.95%). The concentrations of water/DTPA extractable Cd were also reduced, indicating the low Cd mobility after amendment. Finally, the soil became more fertile and active after wermi-remediation. The soil pH, EC, NO₃⁻-N, available P, and K contents increased, while soil SOM, DOC, and NH₄⁺-N contents were decreased. There were higher soil enzyme activities (including acid phosphatase activity, β-glucosidase activity, and urease activity) among treatments with earthworms. Additionally, the operational taxonomic units (OTUs) increased by 100–150 units, and the higher chao1 and Shannon indexes indicated the enhanced microbial community after wermi-remediation, especially among treatment with EDTA and bean dregs. Therefore, we concluded that earthworms, alone or combined with EDTA and bean dregs, are feasible for the remediation of Cd-contaminated soil.

Humic acid (HA) plays vital roles in regulating the environmental behaviors of metals and thus their toxicity to biota. However, the inner relation between metal bioavailability to soil organisms and the presence of HA with different molecular weight (Mw) is not well documented. In this study, we separated HAs into four fractions with Mw range of 5-30k Da, and discussed their ability to alleviating the toxicity of Cd and Pb to earthworm. The bioaccumulation capacities (Cₘₐₓ) increased in order of: UF1<UF2<UF3<UF4, which is in line with the variations of bioavailable concentrations of Cd and Pb in soil. Variations of Mw and binding capacities of HA determine the accumulation behavior in soil solution. The unsatisfactory of biotic ligand model fitting and the differences in fractions of the total biotic ligand sites (f) in earthworm bound by Cd and Pb suggested that only free species of Cd could be considered as biological available to earthworm, while the Pb–HAs complexes have potential ability to interact with earthworm membrane. Antioxidant enzymes are effective biomarkers, and HA with lower Mw play more important roles in restricting the toxicity of soil Cd and Pb to earthworm. These results reveal the different mechanism for HA controlling metal bioavailability between Cd and Pb in soil environment.

Concentrations as high as thousands of milligrams per kilogram (dry weight) of nonylphenol (NP), an endocrine-disrupting chemical of great concern, have been reported in soil. Soil is considered one of the primary pathways for exposure of crop plants to NP. However, there have been few studies on the toxicity of soil NP to crop plants, especially with comprehensive consideration of the application of organic fertiliser which is a common agricultural practice. In this study, tomato plants were grown in soils treated with NP in the presence and/or absence of earthworm casts (EWCs). After four weeks, we tested the physiological and biochemical responses (accumulative levels of hydrogen peroxide (H₂O₂) and superoxide anion radicals (O₂-·), total chlorophyll content, degree of membrane lipid peroxidation, activities of defence-related enzymes, and level of DNA damage) and the changes in plant growth (elongation and biomass). The growth inhibition, reactive oxygen species (H₂O₂ and O₂-·) accumulation, decrease in chlorophyll content, increase in activity of defence-related enzymes (including superoxide dismutase, peroxidase, catalase, ascorbate peroxidase, glutathione S-transferase and glutathione reductase), enhancement of membrane lipid peroxidation, and DNA damage in NP-treated seedlings were clearly reversed by the intervention of EWCs. In particular, the suppressed elongation, biomass, and chlorophyll content in tomato plants exposed to NP alone were significantly restored by EWCs to even greater levels than those of the undisturbed control. In other words, EWCs could efficiently invigorate the photosynthesis of crops via up-regulating the chlorophyll content, thereby overwhelming the NP stress on plant growth. Accordingly, except for reducing the bioavailability of soil NP as reported in our previous study, EWCs could also help crop plants to cope with NP stress by strengthening their stress resistance ability. Our findings are of practical significance for the formulation of strategies to relieve the negative effects of soil NP on crop growth.