Els compostos orgànics volàtils del sòl

The soil is a huge reservoir and source of biogenic volatile organic compounds (bVOCs), which are synthesized by underground living organisms and plant roots, or formed from decomposing litter and dead organic material. This article reviews the scarce available data on the exchange of VOCs between soil and atmosphere and the biological and physical processes allowing diffusion of volatiles in the soil. Soil can function either as a sink or as a source of bVOCs. Microorganisms and the plant root system are the major sources for bVOCs, in particular, the microbial decomposition of plant litter is one of the most important contributions to soil VOC emissions. Soil VOC emissions into the atmosphere are often 1-2(0-3) orders of magnitude lower than those from aboveground vegetation. The current methodology for detecting belowground volatiles is described. Characterization of bVOC emission patterns—i.e., VOCs profiling—is discussed as is a non-destructive fingerprint for the detection of soil microorganisms. Finally, root VOCs and their role in plant defense strategies against pathogens are summarized.