Size- and concentration-dependent effects of microplastics on soil aggregate formation and properties.

Plastics fragment and threaten soil ecosystems. Degradation of soil structure is one of the risks. Despite this, data on impacts of different sized microplastics (MPs) on soil aggregates is lacking. This study systematically investigated the effects of pristine polyethylene powders of different sizes (< 35, < 125, < 500 µm) and concentrations (0, 0.1, 1.0, 10 wt%) on aggregate formation and their properties for two contrasting soils (woodland soil, WS; agricultural soil, AS). 75 day wet-dry cycles produced newly-formed aggregates in all treatments. MP size and concentration impacted the incorporation of MPs in aggregates and this varied with aggregate size; the size distribution of aggregates also varied with MP size and concentration. Aggregates produced in soil containing 10 wt% < 35 µm MPs had significantly lower MWDs (mean weight diameters) than controls. The wettability of aggregates (> 4 mm) reduced with increasing MP exposure concentration and decreasing MP exposure size. MP incorporation decreased the water stability of aggregates (1-2 mm) in WS but increased it in AS. The particle density of aggregates (> 4 mm) significantly decreased with increasing MP concentration, whereas MP size had no effect. As MPs breakdown, fragment and become smaller over time, their potential risk to the aggregated structure of soil increases.

Polyethylene microplastic can adsorb phosphate but is unlikely to limit its availability in soil.

In plant growth experiments, the presence of microplastics (MPs) often reduces plant growth. We conducted laboratory experiments to investigate the potential of microplastics to adsorb the major soil nutrient phosphate; adsorption to MPs was then compared to adsorption to soil. Adsorption experiments used two contrasting soils, pristine high density polyethylene and artificially weathered material (the same material but exposed to 185 nm UV light for 420 h over 105 days), phosphate solutions (dissolved KH2PO4) ranging from 0.2 to 200 mg L-1 and a solid (g) to liquid (mL) ratio of 1: 150 at different values of pH (2-12) and different concentrations of background electrolyte (0.00-0.10 M NaNO3). The adsorption data were best fitted to linear and Freundlich isotherms. In initial experiments where pH was not fixed and with a background electrolyte of 0.10 M NaNO3, Kd values ranged from 3.37 to 27.65 L kg-1, log Kf from 1.21 to 1.96 and 1/n from 0.36 to 0.84. Exposure of the MP to 185 nm UV radiation led to the appearance of a C=O functional group in the MP; the partition coefficient Kd, calculated from the linear isotherm did not increase but the logKf value derived from fits to the Freundlich isotherm increased by a factor of 1.5. Kd values for soils were 3-7.5 times greater than those for MPs and log Kf values 1.1-1.7 greater. In the experiments in which initial pH and ionic strength were varied, adsorption was similar across all treatments with adsorption parameters for the higher organic content soil sometimes having the highest values and the pristine microplastic the lowest. In the desorption experiments most of the adsorbed phosphate desorbed. Overall our findings indicate that despite their ability to adsorb phosphate, MPs are unlikely to control the fate and behaviour of phosphate in soil.

Ethanol, not water, should be used as the dispersant when measuring microplastic particle size distribution by laser diffraction.

Size distribution is a crucial characteristic of microplastics (MPs). A typical method for measuring this property is wet laser diffraction. However, when measuring size distributions of MPs, despite it being a poor dispersant for many MPs, water is commonly selected, potentially limiting the reliability of reported measurements. To evaluate dispersant suitability, different aqueous concentrations of ethanol (0, 10, 20, 30, 40, 50, 75, 100 wt%) and aqueous solutions of 0.001 wt% Triton X-100 and a mixture comprising 10 wt% sodium pyrophosphate and 10 wt% methanol were used as dispersants in a laser granulometer (Mastersizer 2000) to determine particle size distributions (PSDs) of granular polyethylene MP35, MP125 and MP500 particles (nominally <35, <125 and, < 500 µm in size). The reliability of the PSDs depended on the dispersant used and size of primary MPs. With increasing ethanol concentrations, PSD curves of MP35 particles shifted from multi-modal to mono-modal distributions. The measured size distribution reduced from 1588.7 to 4.5 µm in water to 39.9 to 0.1 µm in 100 wt% ethanol. Generally, as ethanol concentration increased, uncertainty associated with the PSD parameters decreased. Although Triton X-100 and the mixed solution also showed better dispersion than water, measured particle sizes and coefficient of variation (COV, %) were notably larger than those for 100 wt% ethanol. Similar trends were observed for larger-sized MP125 and MP500 particles, but differences in PSD curves, PSD parameters, and COV (%) among dispersants were less pronounced. In all dispersants, the volume weighted mean diameters (VWMD) in 100 wt% ethanol (MP35: 14.1 µm, MP125: 102.5 µm, MP500: 300.0 µm) were smallest and close to diameters determined from microscope observations (MP35: 14.6 µm, MP125: 109.0 µm, MP500: 310.6 µm). Therefore, for accurate determinations of the PSDs of MP by wet laser diffraction, ethanol rather than water should be used as the dispersant.

Metal removal from soil leachates using DTPA-functionalised maghemite nanoparticles, a potential soil washing technology.

There is significant current interest in the application of magnetic (magnetite or maghemite) nanoparticles functionalised with chelating agents for the environmental remediation of metal contaminated waters and solutions. Whilst there is a body of knowledge about the potential remediation efficacy of such engineered nanoparticles from studies involving synthetic solutions of single metals, there is relatively little data involving mixed-metal solutions and virtually no studies about nanoparticle performance in chemically complex environmental solutions representing those to which a scaled-up nanoremediation process might eventually be applied. Therefore, we investigated the ability of diethylenetriaminepentaacetic acid (DTPA)-functionalised, silica-coated maghemite nanoparticles to extract potentially toxic (Cd, Co, Cu) and "non-toxic" (Ca, Mg) metals from solution (initial [metal] = 10 mg L-1; pH range: 2-8) and to extract a wider range of elements (As, Ca, Cd, Co, Cr, Cu, Mg, Na, Pb, Zn) from leachate obtained from 10 different contaminated soils with variable initial pH, (semi-)metal and dissolved organic carbon (DOC) concentrations. The functionalised nanoparticles could extract the potentially toxic metals with high efficiency (in general >70%) from single metal solutions and with efficiencies that were either unaffected or reduced from the soil leachates. Kd values remained high (>500 L kg-1), even for the soil leachate extractions. Our findings show that DOC and relatively high concentrations of non-toxic elements do not necessarily reduce the efficiency of metal contaminant removal by DTPA-functionalised magnetic nanoparticles and thus demonstrate the remediation potential of such particles when added to chemically complex soil-derived contaminated solutions.

Adsorption of Pb and Zn from binary metal solutions and in the presence of dissolved organic carbon by DTPA-functionalised, silica-coated magnetic nanoparticles.

The ability of diethylenetriaminepentaacetic acid (DTPA)-functionalised, silica-coated magnetic nanoparticles to adsorb Pb and Zn from single and bi-metallic metal solutions and from solutions containing dissolved organic carbon was assessed. In all experiments 10 mL solutions containing 10 mg of nanoparticles were used. For single metal solutions (10 mg L-1 Pb or Zn) at pH 2 to 8, extraction efficiencies were typically >70%. In bi-metallic experiments, examining the effect of a background of either Zn or Pb (0.025 mmol L-1) on the adsorption of variable concentrations (0-0.045 mmol L-1) of the other metal (Pb or Zn, respectively) adsorption was well modelled by linear isotherms (R2 > 0.60; p ≤ 0.001) and Pb was preferentially adsorbed relative to Zn. In dissolved organic carbon experiments, the presence of fulvic acid (0, 2.1 and 21 mg DOC L-1) reduced Pb and Zn adsorption from 0.01, 0.1 and 1.0 mmol L-1 solutions. However, even at 21 mg DOC L-1 fulvic acid, extraction efficiencies from 0.01 to 0.1 mmol L-1 solutions remained >80% (Pb) and >50% (Zn). Decreases in extraction efficiency were significant between initial metal concentrations of 0.1 and 1.0 mmol L-1 indicating that at metal loadings between c. 100 mg kg-1 and 300 mg kg-1 occupancy of adsorption sites began to limit further adsorption. The nanoparticles have the potential to perform effectively as metal adsorbents in systems containing more than one metal and dissolved organic carbon at a range of pH values.

Does ochre have the potential to be a remedial treatment for As-contaminated soils?

Ochre is an iron oxyhydroxide-rich waste that accumulates in water bodies associated with disused mines. Laboratory experiments were conducted to examine the potential of four different ochres to be used as remedial agents for As contaminated soils. The ochres removed As from solution (200 and 500 mg L(-1)) in adsorption experiments at pH 3 and 8 and, when added to As contaminated soil (5% w/w) significantly reduced As release to solution. In both these experiments the highest surface area ochres performed best. The impact of ochre amendments on uptake of As from soil by plants and humans and release of As to ground water was assessed in a year-long incubation study. Ochres increased soil pH and reduced CaCl2 extractable As but had no consistent effect on plant growth, plant As uptake or As extraction in physiologically-based extraction tests. Ochre may be better used for water treatment than soil remediation.

Renal diseases in adults with cystic fibrosis: a 40 year single centre experience.

BACKGROUND: There is a sizable literature describing renal disease in patients with cystic fibrosis. Previous studies have focused on single disease processes alone, most commonly renal stone disease or acute kidney injury. In this study we report for the first time on the prevalence of all forms of renal disease in a cystic fibrosis population. METHODS: A retrospective review of adult patients with cystic fibrosis attending the Adult Cystic Fibrosis Department at the Royal Brompton Hospital was carried out by searching the department's database to identify patients with renal problems and subsequently retrieving clinical information from medical notes. RESULTS: The prevalence of all renal diseases in our population was 5.1 %. The most commonly identified problem was renal stones. At 2.0 % the prevalence of renal stones in adult patients with cystic fibrosis was comparable to the general population. A range of other renal diseases were identified, the next most common being drug-induced acute kidney injury. CONCLUSIONS: A range of cystic fibrosis independent and attributable diseases has been identified but no cystic fibrosis specific disease. In contrast to other cystic fibrosis centres no increased prevalence of renal stones was found.

An energy budget agent-based model of earthworm populations and its application to study the effects of pesticides.

Earthworms are important organisms in soil communities and so are used as model organisms in environmental risk assessments of chemicals. However current risk assessments of soil invertebrates are based on short-term laboratory studies, of limited ecological relevance, supplemented if necessary by site-specific field trials, which sometimes are challenging to apply across the whole agricultural landscape. Here, we investigate whether population responses to environmental stressors and pesticide exposure can be accurately predicted by combining energy budget and agent-based models (ABMs), based on knowledge of how individuals respond to their local circumstances. A simple energy budget model was implemented within each earthworm Eisenia fetida in the ABM, based on a priori parameter estimates. From broadly accepted physiological principles, simple algorithms specify how energy acquisition and expenditure drive life cycle processes. Each individual allocates energy between maintenance, growth and/or reproduction under varying conditions of food density, soil temperature and soil moisture. When simulating published experiments, good model fits were obtained to experimental data on individual growth, reproduction and starvation. Using the energy budget model as a platform we developed methods to identify which of the physiological parameters in the energy budget model (rates of ingestion, maintenance, growth or reproduction) are primarily affected by pesticide applications, producing four hypotheses about how toxicity acts. We tested these hypotheses by comparing model outputs with published toxicity data on the effects of copper oxychloride and chlorpyrifos on E. fetida. Both growth and reproduction were directly affected in experiments in which sufficient food was provided, whilst maintenance was targeted under food limitation. Although we only incorporate toxic effects at the individual level we show how ABMs can readily extrapolate to larger scales by providing good model fits to field population data. The ability of the presented model to fit the available field and laboratory data for E. fetida demonstrates the promise of the agent-based approach in ecology, by showing how biological knowledge can be used to make ecological inferences. Further work is required to extend the approach to populations of more ecologically relevant species studied at the field scale. Such a model could help extrapolate from laboratory to field conditions and from one set of field conditions to another or from species to species.

A retrospective analysis of the impact of azithromycin maintenance therapy on adults attending a UK cystic fibrosis clinic.

BACKGROUND: Azithromycin is widely used as an immunomodulatory agent in the treatment of cystic fibrosis with previous literature documenting improvements in lung function and a reduction in infective exacerbations. The maximal study period in adults has been six months. METHODS: 81 adult patients taking continuous azithromycin were retrospectively identified. Percentage predicted FEV(1) and courses of intravenous antibiotics were examined at yearly intervals two years prior to and two years after azithromycin initiation. RESULTS: FEV(1) deteriorated in the two years before starting azithromycin by a mean of 2.02% per year. In the year following initiation, FEV(1) increased by 1.15% (P=0.01). However, a mean 2.58% reduction was observed in year two. There was no statistically significant effect on courses of intravenous antibiotics. CONCLUSIONS: Azithromycin resulted in an improved FEV(1) at year one. This effect was not sustained beyond the first year of treatment.

Improved survival at low lung function in cystic fibrosis: cohort study from 1990 to 2007.

OBJECTIVES: To evaluate the survival of patients with cystic fibrosis whose lung function has deteriorated to a forced expiratory volume in one second (FEV(1)) below 30% predicted in the recent treatment era and to explore factors associated with any change in survival. Design Cohort study. SETTING: Adult cystic fibrosis unit in London. PARTICIPANTS: 276 patients (147 (53%) male) whose FEV(1) was first observed to be less than 30% predicted between 1 January 1990 and 31 December 2003. MAIN OUTCOME MEASURE: Survival during follow-up to 31 December 2007 in two year sub-cohorts. RESULTS: Median survival improved from 1.2 years in the 1990-1 group to 5.3 years in the 2002-3 group, with a marked improvement in survival from 1994. The use of nebulised recombinant human DNase was significantly associated with a reduced risk of death (hazard ratio 0.59, 95% confidence interval 0.44 to 0.79). Significantly increased risks were associated with a body mass index under 19 (hazard ratio 1.52, 1.10 to 2.10), long term oxygen therapy (3.52, 2.49 to 4.99), and nebulised antibiotics (1.84, 1.05 to 3.22). CONCLUSION: A marked improvement has occurred in the survival of patients with cystic fibrosis with an FEV(1) less than 30% predicted. Secondary analyses suggest that some of this improvement may be due to use of recombinant human DNase.

Twice vs three-times daily antibiotics in the treatment of pulmonary exacerbations of cystic fibrosis.

BACKGROUND: Once daily dosing of aminoglycosides is widely used but is limited by the inconvenience of the slow infusion it requires and the associated three-times daily infusion of a beta-lactam. Twice daily tobramycin can be given as a slow IV bolus and may be more convenient. This study compares twice with three-times daily dosing of both tobramycin and ceftazidime. METHODS: This was a randomised, open-label, parallel group trial. CF patients presenting with an infective exacerbation were randomised to either twice or three-times daily ceftazidime and tobramycin. Markers of treatment efficacy and safety were measured in the two groups. The primary outcome measure was improvement in FEV1. RESULTS: 146 patients were randomised into the study. There was no significant difference in the two groups for improvement in FEV1% predicted (9.93% and 7.98% for twice daily and three-times daily respectively) and similar times to next exacerbation. There were no differences in the incidence of treatment failure, nephrotoxicity and ototoxicity. DISCUSSION: This study confirms that twice daily dosing of both tobramycin and ceftazidime is safe and effective and may be considered more convenient than current dosing schedules.

Cystic fibrosis and survival to 40 years: a study of cystic fibrosis transmembrane conductance regulator function.

Significant survival heterogeneity exists in cystic fibrosis. Our aim was to determine whether residual function of the cystic fibrosis transmembrane conductance regulator (CFTR) is present in long-term survivors with severe mutations. Nasal potential difference (PD) and sweat chloride were measured in 34 long-term survivors (aged ≥ 40 yrs) and compared with young patients (18-23 yrs) with severe (n = 30) and mild (n = 31) lung disease. Baseline PD was not significantly different across the three groups (long-term survivors, -42.8 (range -71.0- -20.5) mV; young/mild, -40.5 (-58.8- -19.5) mV; young/severe,-46.3 (-74.0- -20.0) mV). Response to amiloride (ΔAmil) was significantly different across the three groups (p = 0.01); long-term survivors had values (27.8 (range 8.5-46) mV) which were not different to either young group, but the young/severe group had significantly higher values (29.5 (11-47) mV) than those in the young/mild group (22.0 (7-39) mV; p<0.01). Baseline PD and ΔAmil were associated with forced expiratory volume in 1 s (FEV1) (co-efficient (95% CI) -0.13 (-0.23- -0.03); p = 0.009 and -0.12 (-0.20- -0.04); p = 0.003, respectively). Sweat chloride was lowest (p <0.05) in the young/severe group (93.5 (74-111) mmol·L⁻¹ versus 98.8 (76.5-116.0) mmol·L⁻¹; long-term survivors; and 99.5 (80.0-113.5) mmol·L⁻¹; young/mild). Δ Amil is associated with FEV1 but our findings indicate that long-term survival cannot be explained by residual CFTR function when measurements are taken in later life.

Cystic fibrosis and survival to 40 years: a case-control study.

The clinical course of patients with cystic fibrosis (CF) is variable and probably determined by many interacting factors. We aimed to examine the influence of early social and clinical factors on long-term survival. A case-control study of adult CF patients was used to compare long-term survivors (aged ≥ 40 yrs) with patients who died before reaching 30 yrs of age. Each case (n = 78) was matched by birth date with at least one control (n = 152), after exclusion of "late diagnosis" patients. Probability-weighted logistic regression models were used to identify influences on survival. Factors resulting in increased probabilities of survival included high body mass index (OR 1.76, 95% CI 1.40-2.22), forced expiratory volume in 1 s (OR per 5% increase 1.54, 95% CI 1.32-1.80), and forced vital capacity (OR per 5% increase 1.54, 95% CI 1.33-1.78) at transfer to the adult clinic and the exclusive use of oral antibiotics (OR 8.31, 95% CI 3.02-22.88). Factors resulting in decreased probabilities of survival were Pseudomonas aeruginosa acquisition (OR 0.18, 95% 0.05-0.65) or pneumothorax before transfer to the adult clinic (OR 0.02, 95% CI 0.004-0.08) and referral from a paediatric clinic in a deprived area (OR 0.13, 95% CI 0.04-0.38). Long-term survival is associated with the clinical features present by the time of referral to an adult clinic. Even "early-diagnosis" disease appears to have different phenotypes, possibly independent of CF gene function, that have different survival patterns.

Beyond postural drainage and percussion: Airway clearance in people with cystic fibrosis.

BACKGROUND: Evidence indicates that there are no statistically significant differences in effectiveness among the airway clearance techniques (ACTs) of active cycle of breathing, autogenic drainage, positive expiratory pressure (PEP) or oscillating PEP in the short-term, but are there differences in the long-term (one year)? The objective of the study was to demonstrate non-inferiority in the long-term. METHODS: Seventy-five people with cystic fibrosis entered the prospective, randomised controlled trial of these five different ACTs. The primary outcome measure was forced expiratory volume in one second (FEV(1)). Secondary outcome measures included exercise capacity and health related quality of life. RESULTS: Using intention to treat, data were available on 65 subjects at the end of the study period. There were no statistically significant differences among the regimens in the primary outcome measurement of FEV(1) (p=0.35). CONCLUSION: In different countries either one or several airway clearance regimens are used. This study provides evidence in support of current practices.

Molecular genetic differentiation in earthworms inhabiting a heterogeneous Pb-polluted landscape.

A Pb-mine site situated on acidic soil, but comprising of Ca-enriched islands around derelict buildings was used to study the spatial pattern of genetic diversity in Lumbricus rubellus. Two distinct genetic lineages ('A' and 'B'), differentiated at both the mitochondrial (mtDNA COII) and nuclear level (AFLPs) were revealed with a mean inter-lineage mtDNA sequence divergence of approximately 13%, indicative of a cryptic species complex. AFLP analysis indicates that lineage A individuals within one central 'ecological island' site are uniquely clustered, with little genetic overlap with lineage A individuals at the two peripheral sites. FTIR microspectroscopy of Pb-sequestering chloragocytes revealed different phosphate profiles in residents of adjacent acidic and calcareous islands. Bioinformatics found over-representation of Ca pathway genes in EST(Pb) libraries. Subsequent sequencing of a Ca-transport gene, SERCA, revealed mutations in the protein's cytosolic domain. We recommend the mandatory genotyping of all individuals prior to field-based ecotoxicological assays, particularly those using discriminating genomic technologies.

Trends in pathogens colonising the respiratory tract of adult patients with cystic fibrosis, 1985-2005.

INTRODUCTION: The treatment of patients with CF has continued to evolve. We hypothesised that sputum microbiology may have changed as a result of this. METHOD: Retrospective analysis of sputum microbiology from adult CF patients (1985 to 2005) using the Royal Brompton Hospital CF database. RESULTS: Colonisation with Pseudomonas aeruginosa or Staphylococcus aureus between 1985 and 2005 remained stable (77 to 82%, p=0.159; 54 to 47%, p=0.108; respectively). Haemophilus influenzae (48 to 6%; p<0.001), Aspergillus species (18 to 9%; p=0.002) and Burkholderia cepacia complex (9 to 4%; p=0.041) prevalence decreased. Stenotrophomonas maltophilia and MRSA increased (1 to 4%, p=0.02; 1 to 6%, p=0.002, respectively). CONCLUSION: P. aeruginosa colonisation has remained stable; there has been a decline in B. cepacia complex, H. influenzae and Aspergillus sp., and only a small increase in S. maltophilia and MRSA. Intensive antibiotic strategies have been employed, which, so far, have not resulted in clinically significant emergence of new pathogens.

Impact of sewage sludge applications on the biogeochemistry of soils.

This report describes an investigation into the bioavailability and fate of trace metals and their subsequent impact on important soil microbiological functions such as nitrification, denitrification and methane oxidation in low and high Cu containing soils in the presence and absence of residual organic matter from sewage sludge additions made 10 years earlier. The soils being studied are part of long term sewage sludge trials and include a low Cu soil (13.3 mg Cu/kg soil, 4.18 LOI %), left un-amended to serve as a control soil, soil amended with a high Cu sewage sludge (278.3 mg Cu/kg soil, 6.52 LOI %) and soil amended with a low Cu sewage sludge (46.3 mg Cu/kg soil, 6.18 LOI %). Soil was also amended with inorganic metal salts (273.4 mg Cu/kg soil, 4.52 LOI %) to further investigate the impact of Cu in the absence of additional organic matter contained in applied sewage sludge. Data from the first two years of a project are presented which has included field-based studies at long term sewage sludge trials based in Watlington, Oxford, UK and laboratory based studies at the Institute of Grassland & Environmental Research, North Wyke, Devon, UK.

A Cu tolerant population of the earthworm Dendrodrilus rubidus (Savigny, 1862) at Coniston Copper Mines, Cumbria, UK.

Dendrodrilus rubidus were sampled from a mine spoil soil at Coniston Copper Mine, an abandoned Cu mine in Cumbria, UK and a Cu-free control site. Earthworms were maintained for 14d in both Kettering loam and a Moorland soil amended with Cu nitrate. Mortality, condition index, weight change and tissue concentration were determined. In both soils D. rubidus native to the mine site were able to tolerate significantly higher soil Cu concentrations (MWRT, p

Dornase alfa is well tolerated: data from the epidemiologic registry of cystic fibrosis.

After closure of the Epidemiologic Registry of Cystic Fibrosis (ERCF), a comprehensive safety analysis of dornase alfa was performed. A planned subanalysis focused on children under 5 years old. Reported serious adverse events (SAEs) were assigned a preferred term and ascribed to a specific organ system. Possible serious adverse reactions to dornase alfa (SADRs) were identified by reporting clinics. Twenty-eight of 15,865 SAEs (0.18%), occurring in 26 of 6,829 patients ever treated with dornase alfa (0.38%), and no deaths were reported as possible SADRs: most were typical complications of cystic fibrosis (CF). There was no evidence of any unrecognized risk of treatment. During 24,586 patient-years of follow-up (FU) of ever-treated patients, SAEs (mostly typical respiratory complications of CF) were more frequent on-treatment (0.4999/patient-year; 95% CI 0.4921-0.5076) than off-treatment (0.3889; 0.3787-0.3992). This was likely caused by within-patient prescription bias. During 655 patient-years of FU in 328 ever-treated patients under 5 years old, SAEs (mostly pulmonary exacerbations of CF) were slightly less frequent during treatment: 0.2911 (0.2367-0.3455) versus 0.3563 (0.3086-0.4040; ns). Results confirm the safety of dornase alfa in CF patients of all ages. Children under 5 years old tolerate dornase alfa at least as well as older patients.

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.