Pyrolytic characterization of humic substances for forecasting water infiltration response in Mediterranean soils.
In countries at the Mediterranean basin, soil erosion by water-frequently associated with torrential precipitations--is an important land degradation problem. This is strongly related to the los s of soil functionality ando therefore. the knowledge of all factors influencing the soil response to precipitation is essential to select the most suitable strategies for preventing these impacts. This work is based on a detailed study of the molecular composition of the humic matter from Mediterranean soils with the purpose of identifying chemical structures associated to water infiltration capacity of the soils. Soil samples from fourteen ecosystems with marked continental features and seasonal rainfall in Central Spain were collected. Water infiltration was measured in the field and the data were adjusted to Kostiako'vs function. yielding different parameters informing on soil infiltration response. The humic acids isolated from the soils were characterised by pyrolysis-GC/ MS. The efficient pyrolytic cleavage of the recalcitrant C-Cbonded structures yields diagnostic compounds arising from speciflc macromolecular precursors, thus providing structural information on the origin of soil C-forms at the molecular leve!. Major pyrolytic products consisted of well-defined alkyl homologous series and methoxyphenols. in addition to other aromatic compounds (methoxy-Ilacking phenols. alkylbenzenes, carbohydrate-derived furans) and N-compounds (pyrroles. indoles. etcJ The cumulative abundances of the different compound groups were processed by statistical treatments. The results suggested that the dominance of aromatic structures with high degree of condensation. typical of recalcitrant organic matter subjected to complex diagenetic processes. concur in soils with appropriate water infiltration capacity. Conversely. in soils with humic acids with important structural similarity with the precursor plant biomacromolecules (such as carbohydrates or ligninJ a series of problems of soil erosion could arise. The overal results indicated that the pyrolytic information could be used in forecasting soil degradation processes and may help lo select suitable correction practices.
| Main Authors: | , , , , , |
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| Format: | póster de congreso biblioteca |
| Published: |
University of Aston in Birmingham
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| Online Access: | http://hdl.handle.net/10261/122778 |
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