Copper toxicity to earthworms: A comprehensive review and meta-analysis.

Copper can accumulate in agricultural topsoil through the use of Cu-based fungicides, which may harm soil organisms such as earthworms. This study aimed at reviewing the effects of copper on earthworms at different levels of biological organization, and to determine critical values of copper toxicity to earthworms using a meta-analysis and accounting for lethal and sub-lethal effects and different earthworm species and exposure conditions. Endpoints at the sub-individual level were more sensitive than at higher levels of organization. At the individual level, the most sensitive endpoints were reproduction and growth (hatching success, hatchling growth). Hormetic growth was clearly recognized at copper concentrations less than 80 mg kg-1 in dry soil. However, effects at the sub-individual level already occurred at lower concentrations. Considering all the exposure conditions, the calculated weighted means were 113 mg Cu kg-1 dry soil (95% CI -356; 582) for the LC50 (lethal concentration for 50% of the exposed individuals), 94.6 mg Cu kg-1 dry soil (95% CI 14.0; 175) for the EC50 reproduction, and 144 mg Cu kg-1 dry soil (95% CI -12.6; 301) for the EC50 growth or weight change. When accounting for the origin of the soil, earthworms were five times more sensitive to copper (LC50) in natural than in artificial soils. The different factors affecting Cu toxicity to earthworms explain the high variability of these values, making it difficult to derive thresholds. However, considering the potential negative effects of copper on earthworms, attention should be given to the more sustainable use of human-contributed copper in agricultural soils.

Automated computation of femoral angles in dogs from three-dimensional computed tomography reconstructions: Comparison with manual techniques.

The aim of this ex vivo study was to test a novel three-dimensional (3D) automated computer-aided design (CAD) method (aCAD) for the computation of femoral angles in dogs from 3D reconstructions of computed tomography (CT) images. The repeatability and reproducibility of three manual radiography, manual CT reconstructions and the aCAD method for the measurement of three femoral angles were evaluated: (1) anatomical lateral distal femoral angle (aLDFA); (2) femoral neck angle (FNA); and (3) femoral torsion angle (FTA). Femoral angles of 22 femurs obtained from 16 cadavers were measured by three blinded observers. Measurements were repeated three times by each observer for each diagnostic technique. Femoral angle measurements were analysed using a mixed effects linear model for repeated measures to determine the levels of intra-observer agreement (repeatability) and inter-observer agreement (reproducibility). Repeatability and reproducibility of measurements using the aCAD method were excellent (intra-class coefficients, ICCs≥0.98) for all three angles assessed. Manual radiography and CT exhibited excellent agreement for the aLDFA measurement (ICCs≥0.90). However, FNA repeatability and reproducibility were poor (ICCs<0.8), whereas FTA measurement showed slightly higher ICCs values, except for the radiographic reproducibility, which was poor (ICCs<0.8). The computation of the 3D aCAD method provided the highest repeatability and reproducibility among the tested methodologies.

Soil organic matter mobilization by root exudates.

In order to study the different soil organic matter mobilisation by agrarian (Zea mais: cultivars Paolo and Sandek) and forest (Picea abies Karst. and Pinus sylvestris L.) root exudates, three different soils (Dystric Spodic Cambisol--S1, Haplic Luvisol--S2 and Calcaric Cambisol--S3) have been considered. Treating the soils with water (control) or plant root exudates, soil organic matter extracts were obtained. The extracts were characterised by hormone-like activities and gas chromatographic/mass spectrometric (GC/MS) measurements. Water extract and plant root exudates exhibited no hormone-like activity, while the other soil-extracts were endowed with a different hormone-like behaviour. GC/MS data indicated that in the acid soils (S1) Sandek and Picea abies exudates showed a greater ability in extracting organic acid isomers (Cl4COOH, Cl5COOH and Cl7COOH), while in neutral soils (S3) all the exudates were active in separating organic acids. In intermediate conditions (S2), Picea abies and Pinus sylvestris exudates liberated C15COOH isomers, Paolo C11COOH isomers, while Sandek was not effective. The different role of plant root exudates in mobilising bio-molecules from the bulk of the soil is proposed.

Micelle-like conformation of humic substances as revealed by size exclusion chromatography.

To gain further insight into the macromolecular behaviour of humic substances we treated a humic material with simple organic compounds and followed the change in molecular size distribution. Monocarboxylic, dicarboxylic, and tricarboxylic acids shifted the humic absorbance from high to low molecular sizes in size exclusion chromatograms. Mineral acids, phenol, alcohols, were not able to produce the same shift and gave total absorbance at the column void volume as in the case of humic substances alone. Our results are evidence of the micellar behaviour of humic substances in solution and of the importance of hydrophobic bondings in holding humic molecules together. The organic acids enter in the interior of the humic micelle and alter its stereochemical hydrophobic arrangement. In alkaline conditions, the developed negative charges disrupt the apparent high molecular size configuration and disperse the humic material into small-size micelles. This macromolecular property, that we report for the first time, may be of great importance in understanding the biological activity and the overall environmental behaviour of humic substances.

An application of EDXRF on the study of barley seedlings growth on sewage sludge.

An energy dispersive X-ray fluorescence method for trace element analysis in plants (leaves and roots) is presented. The method is characterized by the use of a secondary target excitation, thin specimen, and microwave acid digestion. The accuracy is about 10% and the sensitivity is in the range 10-50 ng/cm2. The analysis time (from dry sample to concentration data) is about 4 x 10(3) s. The effects of Cr in sewage sludge on barley seedling growth is presented.