J. Proupín

Microcalorimetric study of the effect of temperature on microbial activity in soils

Abstract The effect of temperature on the microbial degradation of glucose in soil was studied in a conduction-type microcalorimeter. The microbial growth constant, μ, was calculated from the heat evolution associated with the degradation of carbon source, and the power-time curves recorded at different temperatures. The activation energy was obtained from an Arrhenius-type equation and was found to be 39.57 kJ mol−1. Based on the fact that the pattern of bacterial growth is similar to the transition-state theory for chemical process, values of activation entropy, ΔS≠, and activation free energy, ΔG≠, were calculated. These data can be very useful when studying bacterial growth thermodynamic properties in soil.

Energy evaluation of forest residues originated from pine in Galicia.

Pine residues originated from cuts and forestry tasks were studied with the main objective of using them as an alternative source of energy. Calorific values were measured using a static bomb calorimeter in an oxygen atmosphere. From these measurements a value of 7500 kJkg(-1) for the mean lower heating value of these kind of residues was found. A rational and sustainable exploitation of the calorific energy contained in these residues can yield a gross benefit of 2.8 x 10(8) per year through its transformation in electric energy. The study was made along one year, using samples collected in different previously characterized zones. Some other parameters such as: elementary composition, heavy metal content, flammability, and bioclimatic properties were also determined.

Design of forest biomass energetic maps as a tool to fight forest wildfires

In this paper we are setting the bases for the elaboration of energy maps of forest biomass. It shows the results obtained from the calculation of the calorific values and of the flammabilities of each of the forest species studied in Galicia (NW, Spain) along the year. With these data, it is possible to classify the species in terms of their energy content and of their resistance to forest fire. This classification is useful to draw realistic energy maps. With them, it will be possible to prevent and fight forest fires more effectively. These studies are complemented with chemical analyses of each forest species and bioclimatic diagrams of the areas to be studied. The main equipments used to carry out this research were an isoperibol calorimeter with agitated liquid in a static bomb, an epiradiator, an atomic absorption spectrophotometer and tools for elementary analyses.

New insight into the environmental impact of two imidazolium ionic liquids. Effects on seed germination and soil microbial activity

The next generation of ionic liquids must be synthetized taking into account structures that guarantee the suitable properties for a defined application as well as ecological data. Thus, searching of the right methodologies to know, quickly and efficiently, the ecological effects of these compounds is a preliminary task. The effects of two imidazolium based ionic liquids with different anions, 1-butyl-3-methylimidazolium tetrafluoroborate, [C4C1Im][BF4], and 1-propyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [C3C1Im][NTf2], on seedling emergence of six tree species and on the microbial behaviour of two soils were determined in this work. Results showed that the highest doses of both ionic liquids caused the total inhibition of germination for almost all the species studied and that the seeds are more sensitive to the presence of these compounds than soil microbial activity. Nevertheless, signals of stress and death are observed from the results of heat released by microorganisms after the addition of the highest doses of both ionic liquids. The novelty of this work resides in the enlargement of knowledge of toxicity of ILs on complex organisms such as arboreal species and microbial activity of soils studied for the first time through a microcalorimetric technique.