The fate of 14C-diazinon in compost, compost-amended soil, and uptake by earthworms

A process for disposing of pesticide rinsates using sorption onto organic matter followed by composting is being evaluated. As a part of this evaluation process, we have studied the bioavailability of composted delta-2-14C-diazinon and its degradation products to earthworms (Eisenia foetida Savigny) in 30 and 60 d compost amended soil. After 60 d of composting there was considerable degradation of diazinon (95%) and a corresponding increase in the primary hydrolysis product, 2-isopropyl-4-methyl-6-hydroxypyrimidine (IMHP) as determined by high performance thin layer chromatography (HPTLC). Approximately 50% of the radioactivity became incorporated into the non-extractable fractions associated with composted organic matter with no measurable amounts of 14CO2 produced during the 60-day composting period. Following addition of the composted materials to soil, diazinon leading to 50% mortality after 14 d of exposure; continued to slowly degrade and become increasingly sorbed/entrapped within the soil-compost matrix. Soil amended with 30-d composted diazinon was toxic to earthworms whereas, no mortality was observed in those earthworms exposed to the 60-d composted diazinon. However, earthworms exposed to 30-d and 60-d composted diazinon were found to have similar levels of radioactivity in their tissues. The majority of the radioactivity in earthworms exposed 60-d composted diazinon was either unextractably bound within the earthworm tissue or was not acetone soluble. Most of the radioactivity that could be extracted with acetone was not separated by the two HPTLC methods we used. This study demonstrates that composting high concentrations of diazinon can greatly reduce toxicity and the amount of diazinon that is bioavailable to a representative soil macroinvertebrate (E. foetida).     

Effects of phenanthrene on the mortality, growth, and anti-oxidant system of earthworms (Eisenia fetida) under laboratory conditions

To assess the toxic effects of phenanthrene on earthworms, we exposed Eisenia fetida to artificial soils supplemented with different concentrations (0.5, 2.5, 12.5, mgkg(-1) soil) of phenanthrene. The residual phenanthrene in the soil, the bioaccumulation of phenanthrene in earthworms, and the subsequent effects of phenanthrene on growth, anti-oxidant enzyme activities, and lipid peroxidation (LPO) were determined. The degradation rate of low concentrations of phenanthrene was faster than it was for higher concentrations, and the degradation half-life was 7.3d (0.5 mgkg(-1)). Bioaccumulation of phenanthrene in the earthworms decreased the phenanthrene concentration in soils, and phenanthrene content in the earthworms significantly increased with increasing initial soil concentrations. Phenanthrene had a significant effect on E. fetida growth, and the 14-d LC(50) was calculated as 40.67 mgkg(-1). Statistical analysis of the growth inhibition rate showed that the concentration and duration of exposure had significant effects on growth inhibition (p<0.001). Superoxide dismutase (SOD) activity increased at the beginning (2 and 7d) and decreased in the end (14 and 28 d). Catalase (CAT) activity in all treatments was inhibited from 1 to 14 d of exposure. However, no significant perturbations in malondialdehyde (MDA) content were noted between control and phenanthrene-treated earthworms except after 2d of exposure. These results revealed that bioaccumulation of phenanthrene in E. fetida caused concentration-dependent, sub-lethal toxicity. Growth and superoxide dismutase activity can be regarded as sensitive parameters for evaluating the toxicity of phenanthrene to earthworms.     

Habitat type-based bioaccumulation and risk assessment of metal and As contamination in earthworms, beetles and woodlice

The present study investigated the contribution of environmental factors to the accumulation of As, Cd, Cu, Pb and Zn in earthworms, beetles and woodlice, and framed within an exposure assessment of the European hedgehog. Soil and invertebrate samples were collected in three distinct habitat types. Results showed habitat-specific differences in soil and invertebrate metal concentrations and bioaccumulation factors when normalized to soil metal concentration. Further multiple regression analysis showed residual variability (habitat differences) in bioaccumulation that could not be fully explained by differences in soil metal contamination, pH or organic carbon (OC). Therefore, the study demonstrated that in bioaccumulation studies involving terrestrial invertebrates or in risk assessment of metals, it is not sufficient to differentiate habitat types on general soil characteristics such as pH and/or OC alone. Furthermore, simple generic soil risk assessments for Cd and Cu showed that risk characterization was more accurate when performed in a habitat-specific way.     

Modelling the accumulation of hydrophobic organic chemicals in earthworms

In this paper a method is developed which can be used to estimate the body burden of organic hydrophobic chemicals in earthworms. In contrast to the equilibrium partitioning theory, two routes of uptake are incorporated: uptake from interstitial water and dietary uptake. Although many uncertainties still remain, calculations show that for earthworms steady state body burdens are mainly determined by uptake from interstitial water. Under most circumstances, the contribution of dietary uptake is small, except for hydrophobic chemicals (log K_ow > 5) in soils with a high organic matter (OM) content of ≈ 20 %. Under those conditions, estimates of the steady state body burden calculated with the equilibrium partitioning model, in which only uptake from interstitial water is taken into account, might result in a small underestimation of the real body burden of chemicals in earthworms.     

Combined toxicity of chlorpyrifos,abamectin, imidacloprid,and acetamiprid on earthworms (Eisenia fetida)

Environmental Science and Pollution Research - Mixed pesticides have been broadly used in agriculture. However, assessing the combined effects of pesticides in the environment is essential for...     

Heavy metal availability,bioaccessibility, and leachability in contaminated soil: effects of pig manure and earthworms

A pot experiment and a leaching experiment were conducted to investigate the effects of earthworms and pig manure on heavy metals (Cd, Pb, and Zn) immobility, in vitro bioaccessibility and leachability under simulated acid rain (SAR). Results showed manure significantly increased soil organic carbon (SOC), dissolved organic carbon (DOC), available phosphorus (AP), total N, total P and pH, and decreased CaCl₂-extractable metals and total heavy metals in water and SAR leachate. The addition of earthworms significantly increased AP (from 0.38 to 1.7 mg kg^?1), and a downward trend in CaCl₂-extractable and total leaching loss of heavy metals were observed. The combined earthworm and manure treatment decreased CaCl₂-extractable Zn, Cd, and Pb. For Na₄P₂O₇-extractable metals, Cd and Pb were decreased with increasing manure application rate. Application of earthworm alone did not contribute to the remediation of heavy metal polluted soils. Considering the effects on heavy metal immobilization and cost, the application of 6% manure was an alternative approach for treating contaminated soils. These findings provide valuable information for risk management during immobilization of heavy metals in contaminated soils.

     

Assessment of a sewage sludge treatment on cadmium, copper and zinc bioavailability in barley, ryegrass and earthworms

The toxicity and bioavailability of metals were assessed to verify the efficiency of a new chemical leaching process (METIX-AC) to minimize the risk of metals found in municipal sewage sludge. For this purpose, sludge samples were spiked with cadmium, copper and/or zinc before being treated using METIX-AC. The sludge decontamination resulted in a removal of spiked metals (79-89%), in a decrease of the more labile fractions, and in a corresponding increase of the residual fraction. The toxicity observed after exposure of two plant species, barley (Hordeum vulgare) and ryegrass (Lolium perenne), and a terrestrial invertebrate, Eisenia andrei, to sludge-soil mixtures, disappeared after treatment, although the adverse effects were minor before treatment. The sludge treatment also significantly decreased the bioaccumulation of cadmium, copper, and zinc in the exposed species. For cadmium, maximum tissue concentrations of 0.45+/-0.08 mg/kg in barley, 0.79+/-0.27 mg/kg in ryegrass, and 21.82+/-1.85 mg/kg in earthworm exposed to sludge before treatment decreased after treatment to values similar to those observed with negative controls.     

Mercury, cadmium and lead concentrations in different ecophysiological groups of earthworms in forest soils

Bioaccumulation of Hg, Cd and Pb by eight ecophysiologically distinct earthworm species was studied in 27 polluted and uncontaminated forest soils. Lowest tissue concentrations of Hg and Cd occurred in epigeic Lumbricus rubellus and highest in endogeic Octolasion cyaneum. Soils dominated by Dendrodrilus rubidus possess a high potential of risk of Pb biomagnification for secondary predators. Bioconcentration factors (soil-earthworm) followed the sequence ranked Cd > Hg > Pb. Ordination plots of redundancy analysis were used to compare HM concentrations in earthworm tissues with soil, leaf litter and root concentrations and with soil pH and CEC. Different ecological categories of earthworms are exposed to Hg, Cd and Pb in the topsoil by atmospheric deposition and accumulate them in their bodies. Species differences in HM concentrations largely reflect differences in food selectivity and niche separation.     

Heavy metal concentrations in soil and earthworms in a floodplain grassland

We determined accumulated heavy metal concentrations (Cd, Pb, Cu, Zn) of earthworms in moderately contaminated floodplain soils. Both soil and mature earthworms were sampled before and after flooding and earthworm species were identified to understand species specific differences in bioconcentration. Accumulated metal concentrations in floodplain earthworms differed before and after flooding. Differences in uptake and elimination mechanisms, in food choice and living habitat of the different earthworm species and changes in speciation of the heavy metals are possible causes for this observation. Regression equations taken from literature, that relate metal accumulation by earthworms in floodplains as a function of metal concentration in soil, performed well when all species specific data were combined in an average accumulation, but did not address differences in accumulation between earthworm species.     

Effect of time and mode of depuration on tissue copper concentrations of the earthworms Eisenia andrei, Lumbricus rubellus and Lumbricus terrestris

Eisenia andrei, Lumbricus rubellus and Lumbricus terrestris were exposed to 250, 250 and 350mgkg(-1) Cu respectively in Cu(NO(3))(2(aq)) amended soil for 28 d. Earthworms were then depurated for 24 to 72h, digested and analysed for Cu and Ti or, subsequent to depuration were dissected to remove any remaining soil particles from the alimentary canal and then digested and analysed. This latter treatment proved impossible for E. andrei due to its small size. Regardless of depuration time, soil particles were retained in the alimentary canal of L. rubellus and L. terrestris. Tissue concentration determinations indicate that E. andrei should be depurated for 24h, L. rubellus for 48h and L. terrestris should be dissected. Ti was bioaccumulated and therefore could not be used as an inert tracer to determine mass of retained soil. Calculations indicate that after 28 d earthworms were still absorbing Cu from soil.     

The effect of earthworms on the fractionation, mobility and bioavailability of Pb, Zn and Cd before and after soil leaching with EDTA

The effect of two ecologically contrasting earthworm species Eisenia fetida (epigeic) and Octolasion tyrtaeum (endogeic) on the fractionation (accessed using sequential extractions), mobility (toxicity characteristic leaching procedure, TCLP) and oral bioavailability (Ruby's physiologically based extraction test, PBET) of Pb, Zn and Cd was studied before and after soil remediation with soil leaching. Twenty-step leaching, with 2.5 mmol kg(-1) EDTA used in each step, removed 58.4%, 25.0% and 68.0% of initial soil Pb, Zn and Cd, respectively, shifted the fractionation of residual heavy metals toward less labile forms, and decreased their mobility by 83.7%, 80.3%, and 90.9%. Pb oral bioavailability was reduced by 3.1-times (in each stomach and intestinal phase). After soil leaching, both earthworm species enriched the carbonate soil fraction in their casts with residual Pb, and increased the Pb bioavailability in the simulated intestinal phase by a factor of 2.4 (E. fetida) and 2.8 (O. tyrtaeum). The concentration of Pb in TCLP leachate from E. fetida casts was 6.2-times higher than in the bulk of the remediated soil. These results indicate that the effect of biotic factors on the availability of heavy metals residual in soil after soil leaching requires consideration.     

蚯蚓生态滤池中蚯蚓与植物对污水净化的作用评估

构建具有不同蚯蚓和植物配置的4个单级蚯蚓生态滤池,依次编号为A(无蚯蚓无植物)、B(有蚯蚓无植物)、C(有蚯蚓栽种芦苇)和D(有蚯蚓栽种水生鸢尾)。通过比较4个滤池在6个月实验期间对化学需氧量(COD)和总氮(TN)的去除效率,系统分析蚯蚓和植物对滤池去除污染物的影响。实验分2个阶段进行:5月上旬至9月上旬,滤池进水碳氮比恒定为6;9月中旬至11月中旬,滤池每周进水碳氮比交替为3、6、9。研究结果表明,蚯蚓对滤池去除COD有一定的促进作用,且作用强度显著受到进水碳氮比的影响。植物的存在与种类对滤池去除COD效率没有显著影响。蚯蚓和植物对滤池的TN去除效率都没有显著影响。滤池进水的碳氮比是显著影响滤池去除TN效率的主要因素。     

Arsenic speciation in field-collected and laboratory-exposed earthworms Lumbricus terrestris

Mature Lumbricus terrestris were host soils and leaf litter were collected from a former arsenic mine in Devon, UK (Devon Great Consols), a former gold mine in Ontario, Canada (Deloro), and an uncontaminated residential garden in Nottingham, UK. Arsenic concentrations determined by inductively coupled plasma-mass spectrometry (ICP-MS) in soils were 16-348 mg kg⁻¹, 6.0-239 mg kg⁻¹ in the earthworms and 8.6 mg kg⁻¹ in leaf litter sampled at Deloro (all dry weight). High performance liquid chromatography (HPLC-ICP-MS) analysis revealed arsenite (As^III), arsenate (As^V) and five organoarsenic species; arsenobetaine (AB), methylarsonate (MA^V), dimethylarsinate (DMA^V), arsenosugar 1 (glycerol sugar), arsenosugar 2 (phosphate sugar), and trimethylarsineoxide (TMAO) in field-collected L. terrestris. Differences were observed in the variety of organoarsenic species present between field sites. Several organoarsenic species were observed in the leaf litter (DMA^V, arsenosugar 2 and TMAO) but not AB. Depuration resulted in higher concentrations of inorganic As being detected in the earthworm whereas the concentration or variety of organoarsenic species was unchanged. Commercially sourced L. terrestris were exposed to As contaminated soil in laboratory mesocosms (1.0, 98, 183, 236, 324 and 436 mg kg⁻¹) without leaf litter and were additionally analyzed using X-ray absorption near edge structure (XANES). Only inorganic As^III and As^V was observed. It is proposed that ingestion of leaf litter and symbiotic processes in the natural soil environment are likely sources of organoarsenic compounds in field-collected L. terrestris.     

Interactions between earthworms and arsenic in the soil environment: a review

Chemical pollution of the environment has become a major source of concern. In particular, many studies have investigated the impact of pollution on biota in the environment. Studies on metalliferous contaminated mine spoil wastes have shown that some soil organisms have the capability to become resistant to metal/metalloid toxicity. Earthworms are known to inhabit arsenic-rich metalliferous soils and, due to their intimate contact with the soil, in both the solid and aqueous phases, are likely to accumulate contaminants present in mine spoil. Earthworms that inhabit metalliferous contaminated soils must have developed mechanisms of resistance to the toxins found in these soils. The mechanisms of resistance are not fully understood; they may involve physiological adaptation (acclimation) or be genetic. This review discusses the relationships between earthworms and arsenic-rich mine spoil wastes, looking critically at resistance and possible mechanisms of resistance, in relation to soil edaphic factors and possible trophic transfer routes.     

Calcium-lead interactions involving earthworms. Part 1: The effect of exogenous calcium on lead accumulation by earthworms under field and laboratory conditions

Earthworms (Lumbricus rubellus and Dendrodrilus rubidus) were collected from several acidic and calcareous abandoned ferrous metalliferous mine sites. Tissue lead concentrations were substantially lower than the total soil lead concentrations, except at one site (Cwmystwyth) where the tissue lead concentrations of both species were approximately 5 to 10 times higher than that of the soil. Soil lead was the major factor in determining the tissue lead concentration, although it was demonstrated that both soil pH and soil calcium concentration could markedly increase the % variance in tissue lead concentration. These findings help explain the apparent anomaly in tissue lead concentrations of earthworms from Cwmystwyth, where the soil is acidic and has exceptionally low calcium concentrations. Soil-liming experiments provided supportive evidence that soil pH, coupled with soil calcium, influences lead accumulation by earthworms, but a filter paper feeding experiment provided unequivocal evidence that soil calcium concentration alone can influence lead accumulation by earthworms. It is concluded that, although lead accumulation by earthworms is influenced by both physico-chemical and biochemical mechanisms, the latter over-rides the former, i.e. soil calcium is more important factor in determining the accumulation of lead earthworms than is soil pH.     

Sub-lethal toxicity of the antiparasitic abamectin on earthworms and the application of neutral red retention time as a biomarker

The antiparasitic abamectin has been proven effective against both endo- and ectoparasites of farm animals and hence used widely in animal husbandry. It may enter the soil environment with the excreta of treated animals. Very little information is available with regard to the sub-lethal effects of abamectin on soil invertebrates, such as earthworms. The objective of this study was to evaluate the toxic effect of abamectin on earthworms, using Eisenia fetida, by analyzing changes in the survival, growth, reproduction and cocoon hatchability of exposed earthworms. Furthermore, a biomarker of the lysosomal membrane stability, measured by neutral red retention time (NRR-time), was also applied. Abamectin showed significant toxicity on the growth of earthworms with increasing concentrations up to 5mg/kg. The most sensitive parameter was reproduction (cocoons production and hatchability) and NRR-time. The number of cocoons was reduced at concentrations above 0.25mg/kg and no cocoons were present at the highest concentration of 5mg/kg. Cocoons exposed to abamectin exhibited a reduced hatching success at concentrations above 1.5mg/kg. The NRR-time was reduced significantly at exposure concentrations of abamectin above 0.25mg/kg. The change in lysosomal membrane stability showed a good correlation with reproduction and may hence be a potential predicator of the effects on earthworm populations.     

Chemical assays of availability to earthworms of polycyclic aromatic hydrocarbons in soil

The bioavailable concentration of an organic pollutant is less than the concentration determined by vigorous extraction of soil. Because bioavailability varies with the particular compound, soil, and aging time, an assay for bioavailability is needed. Three methods were tested: extraction with a 25% aqueous solution of tetrahydrofuran (THF), 95% ethanol, and C18 membranes. Evaluations were conducted with a mixture of four polycyclic aromatic hydrocarbons (PAHs) added to five dissimilar soils and with pyrene as sole PAH added to six soils, and the availability of aged and freshly added compounds was determined. Assimilation by earthworms (Eisenia fetida) was used to assess bioavailability. For extraction with THF and earthworm uptake, the correlation coefficients of determination (R2) for anthracene, chrysene, pyrene, and benzo(a)pyrene added as a mixture exceeded 0.85. The R2 values for assays with the C18 membrane were 0.77 or higher. The values for pyrene added alone were 0.710 and 0.823, respectively. R2 values for assays with ethanol often exceeded 0.87, but lower values were sometimes obtained. We suggest that such solvent or solid-phase extractions may be useful in assessing PAH bioavailability.     

PAH-sequestration capacity of granular and powder activated carbon amendments in soil, and their effects on earthworms and plants

A field lysimeter study was carried out to investigate whether the amendment of 2% powder and granular activated carbon (PAC and GAC) to a soil with moderate PAH contamination had an impact on the PAH bioaccumulation of earthworms and plants, since AC is known to be a strong sorbent for organic pollutants. Furthermore, secondary effects of AC on plants and earthworms were studied through growth and nutrient uptake, and survival and weight gain. Additionally, the effect of AC amendments on soil characteristics like pH, water holding capacity, and the water retention curve of the soil were investigated. Results show that the amendment of 2% PAC had a negative effect on plant growth while the GAC increased the growth rate of plants. PAC was toxic to earthworms, demonstrated by a significant weight loss, while the results for GAC were less clear due to ambiguous results of a field and a parallel laboratory study. Both kinds of AC significantly reduced biota to soil accumulation factors (BSAFs) of PAHs in earthworms and plants. The GAC reduced the BSAFs of earthworms by an average of 47 ± 44% and the PAC amendment reduced them by 72 ± 19%. For the investigated plants the BSAFs were reduced by 46 ± 36% and 53 ± 22% by the GAC and PAC, respectively.     

Endocrine disrupting chemicals accumulate in earthworms exposed to sewage effluent

Endocrine disrupting chemicals (EDCs) can alter endocrine function in exposed animals. Such critical effects, combined with the ubiquity of EDCs in sewage effluent and potentially in tapwater, have led to concerns that they could be major physiological disruptors for wildlife and more controversially for humans. Although sewage effluent is known to be a rich source of EDCs, there is as yet no evidence for EDC uptake by invertebrates that live within the sewage treatment system. Here, we describe the use of an extraction method and GC-MS for the first time to determine levels of EDCs (e.g., dibutylphthalate, dioctylphthalate, bisphenol-A and 17beta-estradiol) in tissue samples from earthworms (Eisenia fetida) living in sewage percolating filter beds and garden soil. To the best of our knowledge, this is the first such use of these techniques to determine EDCs in tissue samples in any organism. We found significantly higher concentrations of these chemicals in the animals from sewage percolating filter beds. Our data suggest that earthworms can be used as bioindicators for EDCs in these substrates and that the animals accumulate these compounds to levels well above those reported for waste water. The potential transfer into the terrestrial food chain and effects on wildlife are discussed.     

A review of studies performed to assess metal uptake by earthworms

Earthworms perform a number of essential functions in soil; the impacts of metals on earthworms are often investigated. In this review we consider the range of earthworm species, types of soil and forms of metal for which metal uptake and accumulation have been studied, the design of these experiments and the quantitative relationships that have been derived to predict earthworm metal body burden. We conclude that there is a need for more studies on earthworm species other than Eisenia fetida in order to apply the large existing database on this earthworm to other, soil dwelling species. To aid comparisons between studies agreement is needed on standard protocols that define exposure and depuration periods and the parameters, such as soil solution composition, soil chemical and physical properties to be measured. It is recommended that more field or terrestrial model ecosystem studies using real contaminated soil rather than metal-amended artificial soils are performed.