Assessment of Diesel Distribution in Undisturbed Soil Cores After Simulated Rain Episodes Using Analytical Chemistry Techniques and X-Ray Computed Microtomography
| Autor: | Balseiro-Romero, M., Mazurier, A., Calviño-Vázquez, B., Monterroso, C., Baveye, P. |
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| Rok vydání: | 2021 |
| Zdroj: | Digital.CSIC. Repositorio Institucional del CSIC instname |
| Popis: | Poster presentado en the SETAC Europe 31st Annual Meeting from 2–6 May 2021 in Seville, Spain. The behaviour of fuel compounds in soil and their fate in the environment have raised much concern in recent years due to the environmental and ecological associated risks. A detailed study of the migration of a simulated diesel spill using analytical and tomographic techniques was carried out using undisturbed soil cores (5.5 cm height x 4 cm diameter) from an agricultural soil (first 5-10 cm) and a forest soil (topsoil, first 5-10 cm; and B horizon 50-60 cm). Packed cores of coarse sand were used as a control. A surface spill of diesel was simulated by adding 3 mL of commercial diesel on top of the cores. Every 48 h, artificial rain episodes were simulated in two batches (8 mL and 7 mL) spaced by 6 hours. Rain intensity was controlled using rain reservoirs with ten hypodermic needles homogeneously distributed and situated at 3 cm over the core surface. Leachates were sampled at the bottom of the cores and analysed for total diesel compounds (TDH) and diesel range organics (DRO, alkanes from 10 to 25 carbons) by gas chromatography coupled to mass spectrometry. The experiment was kept for 4 weeks and the soil in the cores was analysed for TDH and DRO at four different depths, in order to characterise the diesel distribution. In parallel, cores were scanned using an X-ray computed microtomograph (μCT), before and after the experiment, in order to characterise, respectively, the pore space (macroporosity, distribution and connectivity of the pores, tortuosity, etc.) and the probable distribution of residual diesel within. The results showed that the leaching rate of water, the distribution of residual diesel and its migration behaviour inside the cores, were closely related to the characteristics of the pore space. On the other hand, the soil composition (in terms of organic matter and other colloidal components) had a strong influence on the rate at which the diesel abandoned the cores (generally delayed in soil samples with a higher content of organic matter or clays, which exerted a stronger retention), and on the composition of residual diesel (mainly enriched on high-molecular weight alkanes in the upper layers, more strongly retained, and due to evaporation losses of the lightest). These results are of a high significance for understanding the behaviour of fuel spills in real soils, and reflect how the internal structure of the pores and the soil colloidal components play a role in determining the final fate of fuel compounds in the environment. |
| Databáze: | OpenAIRE |
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