Black carbon estimation in French calcareous soils using chemo-thermal oxidation method

We studied the black carbon (BC) content of ca. 405 samples from French topsoil and artificial soil and carbonate mixtures. Our protocol involved three main steps: (i) decarbonation by HCl, (ii) elimination of non-pyrogenic organic carbon in a furnace at 375 degrees C, and (iii) quantification of residual carbon by CHN analysis. BC content increased for calcareous soils according to their carbonates content. Subsequent analyses confirmed the existence of a methodological artefact for BC determination only in calcareous soils. Decarbonation changes the thermal properties of organic matter, creating more recalcitrant carbon than in the initial sample. Higher CaCO3 and organic carbon content results in a more pronounced artefact. The reversal of the first two steps of the chemo-thermal oxidation method (i. e. thermal oxidation before soil decarbonation) eliminates this artefact. Overall, our results suggest that BC content may have been overestimated in a large number of studies on calcareous soils

Effects of azoxystrobin, chlorothalonil and ethoprophos on the reproduction of three terrestrial invertebrates using a Mediterranean soil

The potential terrestrial toxicity of three pesticides, azoxystrobin, chlorothalonil, and ethoprophos was evaluated using reproduction ecotoxicological tests with different non-target species: the collembolan Folsomia candida, the earthworm Eisenia andrei, and the enchytraeid Enchytraeus crypticus. All reproduction tests were performed with natural soil from a Mediterranean agricultural area (with no pesticide residues) in order to improve the relevance of laboratory data to field conditions. Controls were performed with natural and standard artificial soil (OECD 10% OM). The fungicide azoxystrobin showed the highest toxicity to earthworms (EC50 = 42.0 mg a.i. kg−1 dw soil). Collembolans were the most sensitive taxa in terms of sublethal effects of chlorothalonil with an EC50 of 31.1 mg a.i. kg−1 dw soil followed by the earthworms with an EC50 of 40.9 mg a.i. kg−1 dw soil. The insecticide ethoprophos was the most toxic to collembolans affecting their reproduction with an EC50 of 0.027 mg a.i. kg−1 dw soil. Enchytraeids were generally the least sensitive of the three species tested for long-term effects. Earthworms were not always the most sensitive species, emphasizing the need to increase the number of mandatory assays with key non-target organisms in the environmental risk assessment of pesticidesinfo:eu-repo/semantics/publishedVersio