All physical, chemical and biological processes are accompanied by changes in energy, which means heat. This makes calorimetry one of the most suitable techniques to study all these processes. Soil is a typical example of this, mainly due to the fact that its behavior is related to all these processes. Soil microorganism, microbial biomass and organic matter are the most important parameters of soil quality and they could be evaluated, at the same time, using calorimetry, more generally by ITC . In this study, we have evaluated the effects of seasonal sampling as well as the influence of the experimental condition on the glucose degradation by Brazilian soil, using calorimetry. The results show a decrease in the metabolism of the soil microorganisms upon storage from one month (?Hmet= -5.80 J g-1) to three months (?Hmet= -2.73 J g-1) and so on. On the other hand, the oxygen atmosphere seems to decrease the metabolism (?Hmet= -5.87 J g-1) in comparison with the CO2 admission (?Hmet = -10.4 J g-1). These results show the increase of the microorganism stress provoked by the adverse condition of the carbon dioxide addition. It is an important factor in order to study the influence of the greenhouse effect on the soil metabolism, and vice versa. Other results showed the increase of the metabolic energy with the increase of the As3+ addition, from (?Hmet= -9.99 J g-1) for 50 ppm of As3+ to (?Hmet = -11.9 J g-1) for 1,000 ppm and a decrease of the metabolism concomitant with the herbicide (glyphosate, 0.13M) addition (?Hmet= -2.44 J g-1).

Micro-calorimitric evaluation of seasonal climatic variation on soil microbial activities

243rd National Meeting (2012)

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