MED_Soil Research Group

Sevilla, Spain

MED_Soil Research Group

Sevilla, Spain
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Jimenez-Morillo N.T.,IRNAS CSIC | Spangenberg J.E.,University of Lausanne | Miller A.Z.,IRNAS CSIC | Jordan A.,MED_Soil Research Group | And 3 more authors.
Environmental Research | Year: 2017

Soil water repellency (hydrophobicity) prevents water from wetting or infiltrating soils, triggering changes in the ecosystems. Fire may develop, enhance or destroy hydrophobicity in previously wettable or water-repellent soils. Soil water repellency is mostly influenced by the quality and quantity of soil organic matter, particularly the lipid fraction. Here we report the results of a study on the effect of fire on the distribution of soil lipids and their role in the hydrophobicity grade of six particle size fractions (2–1, 1–0.5, 0.5–0.25, 0.25–0.1, 0.1–0.05 and <0.05 mm) of an Arenosol under Quercus suber canopy at the Doñana National Park (SW-Spain). Hydrophobicity was determined using water drop penetration time test. Field emission scanning electron microscopy (FESEM) was used to assess the presence and morphology of the inorganic and organic soil components in the particle size fractions. Soil lipids were Soxhlet extracted with a dichloromethane-methanol mixture. Fatty acids (FAs) and neutral lipids were separated, derivatized, identified and quantified by gas chromatography/mass spectrometry and gas chromatography/flame ionization detection. The hydrophobicity values of soil samples and fractions were statistically different (P < 0.05), for both, the unburnt and burnt soils, and particle size fractions. All samples displayed a similar distribution of FAs, straight-chain saturated acids in the C14–C32 range, and neutral lipids (n-alkan-1-ols, n-alkanes), only differing in their relative abundances. Among possible biogeochemical mechanisms responsible for the changes in soil lipids, the observed depletion of long chain FAs (C≥24) in the coarse fraction is best explained by thermal cracking caused by the heat of the fire. The enrichment of long chain FAs observed in other fractions suggests possible exogenous additions of charred, lipid-rich, material, like cork suberin or other plant-derived macromolecules (cutins). Principal component analysis was used to study the relationships between hydrophobicity with soil organic matter and its different components. Extractable organic matter (EOM) and specifically long chain FAs content were positively correlated to soil hydrophobicity. Therefore, the latter could be used as biomarkers surrogated to hydrophobicity in sandy soils. © 2017 Elsevier Inc.


Fernandez H.M.,University of Algarve | Fernandez H.M.,MED_Soil Research Group | Martins F.M.G.,University of Algarve | Martins F.M.G.,MED_Soil Research Group | And 5 more authors.
Journal of Maps | Year: 2016

Soil erosion has long been the subject of attention for environmental management researchers because it implies the loss of a key natural resource for sustaining life. Several methodologies for soil erosion assessment have been developed; many of these are supported by Geographic Information Systems. This study aims to classify the susceptibility of rainfall-induced erosion at the Serra de Grândola (Portugal), based on the Priority Actions Programme/Regional Activity Centre guidelines for mapping soil erosion on the Mediterranean coast. Results show a low-to-moderate susceptibility to rainfall-induced erosion in the lowlands, becoming moderate to high in the highlands of the Serra de Grândola. © 2016 Helena M. Fernandez


Martins F.M.G.,University of Algarve | Martins F.M.G.,MED_Soil Research Group | Fernandez H.M.,University of Algarve | Fernandez H.M.,MED_Soil Research Group | And 6 more authors.
Journal of Maps | Year: 2016

A Geographic Information Systems-based tool is used for macro-landform classification following the Hammond procedure, based upon a Digital Terrain Model (DTM) created from ordinary Kriging. Gentle slopes, surface curvature, highlands and lowlands areas are derived from the DTM. Combining this information allows the classification of terrain units (landforms). The procedure is applied to the Ria Formosa basin (Southern Portugal), with five different terrain types classified (plains, tablelands, plains with hills, open hills and hills). © 2015 Fernando M. G. Martins.

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