Nieves Barros

• Professor (Full) at University of Santiago de Compostela

Thermal analysis and calorimetry are useful tools for soil research providing different indices enriching the understanding of soil processes. In this work, we test their sensitivity to study the impact on soil of macroscopic forestry managements applied to eucalypt forest in the northwest of Spain: clearing scrub and thinning. Their impact on soil...

Thermodynamics is a vast area of knowledge with a debatable role in explaining the evolution of ecosystems. In the case of soil ecosystems, this role is still unclear due to difficulties in determining the thermodynamic functions that are involved in the survival and evolution of soils as living systems. The existing knowledge is largely based on t...

The thermodynamic characterization of the soil organic matter could be achieved by different enthalpic models little explored for soil. This paper compares two of them for calculating the enthalpy change, the Gibbs energy change and the entropy change of the soil organic matter combustion reaction, by simultaneous differential scanning calorimetry...

Land use and plant-soil management influence soil organic C stocks and soil properties. This study aimed to identify the main mechanisms by which these factors alter soil organic matter (SOM) dynamics and stocks. Changes in the organic C pools and biochemical quality in different OM compartments were assessed: a) after deforestation and intensive c...

Studying the thermodynamic properties of soil organic matter is a developing field that involves the measurement of the energy stored by the soil. Quantifying soil energy content is still challenging despite different methodological approaches are available to calculate that value. One of the options is the proximate analysis following the guidelin...

This work applies proximate analysis to different soil samples, to explore their potential for future soil thermodynamic characterization.

This work designs a heatwave with a calorimeter to analyze the response of soils from oak forest ecosystems to increasing temperature from 20 to 60 ºC and to cooling from 60 ºC to 20 ºC. Calorimetry measures the heat rate of the soil organic matter decomposition and the response to increasing and decreasing temperatures directly. It was applied to...

Featured Application Energy rules life. All living systems keep themselves alive by balancing the energy input and output by universal thermodynamic principles. Soils are not an exception to this; however, their extraordinary complexity makes them poorly described as a thermodynamic system. This review shows how thermodynamics can be applied to stu...

The evolution of soil terrestrial ecosystems is a subject with difficulties to define their maturity and evolutionary state. In the last century, thermodynamics was one of the options considered by ecologists for that goal. Difficulties in quantifying the thermodynamic parameters needed by the evolutionary theories caused that this subject has been...

Abandonment of croplands ongoing on 220 million ha worldwide contributes strongly to soil restoration by improvement of degraded properties and medium-and long-term carbon (C) sequestration in post-agricultural ecosystems. Two interrelated processes-decomposition and stabilization of soil organic carbon (SOC)-govern SOC dynamics and affect the C so...

The relation between soil organic matter dynamics and temperature is an important research topic, poorly understood yet. This study focuses on the effect of temperature on the heat rate of soil organic matter decomposition using different soil types, by simulating an extreme heat wave with a calorimeter. Heat rates were measured with an automated s...

Calorimetry measures the heat flow of any chemical, physical, and biological reaction and it is considered an important tool in all those scientific disciplines. Calorimetry evolves and focuses on designing more and more sensitive instruments capable of monitoring the heat rate associated with practically all living systems including soil. To study...

Soil samples must usually be stored for a time between collection and measurements of microbial metabolic properties. However, little is known about the influence of storage conditions on microbial metabolism when studied by calorespirometry. Calorespirometry measures the heat rate and the CO2 rate of microbial metabolism, where the ratio of heat a...

Climate change is one of the biggest challenges facing scientists worldwide nowadays. Interdisciplinary knowledge is of paramount importance to climate change research, because climate directly affects all aspects of life on earth: from natural and experimental sciences, to economics, social sciences and human health. The research needed to adapt l...

Understanding the connection between soil biodegradation and temperature is a matter of concern nowadays. Increasing temperature increases the rate at which soil is degraded by microbial action enhancing carbon losses with a negative impact on the atmosphere and water quality. The number of methods allowing these measurements is small, and addition...

Microcalorimetry and BIOLOG are common tools in the study of soil microbial metabolism. When used combined, they may reveal further details about soil microbial metabolic diversity than individually. Through this study, we demonstrated the advantages of such a combinatorial methodology by comparing soil samples from two locations in China, each wit...

The temperature sensitivity of soil carbon decomposition is a subject receiving much attention, but is still limited by insufficient methodologies. It is important to provide new methods and alternative indices connecting soil carbon mineralization with temperature. Calorespirometry constitutes an alternative, but its usefulness and sensitivity for...

The temperature sensitivity of soil organic matter (SOM) is receiving an increasing interest due to its importance in the global carbon cycle and potential feedbacks to climate change. It constitutes a controversial topic in soil science due to different constrains involving the models employed, together with methodological limitations. It is welco...

Wildfire Soil burn severity SOM quality DSC Solid-state 13 C NMR Wildfire has highly variable effects on soil, and different conservation strategies are required to address different levels of soil degradation. Rapid diagnosis of soil burn severity is required to enable the design of emergency post-fire rehabilitation treatments. This study evaluat...

Modelling soil organic matter dynamics requires reproducible and accurate data from several methods that follow such evolution based on changes in soil organic matter properties. The objective of this study is to investigate changes in the chemical, thermal and biological properties of soil organic matter after afforestation using emerging methods...

The study of mechanisms of soil organic matter (SOM) stabilization is a topic of increasing interest due to its direct involvement in the carbon (C) sequestration capacity linked to a certain soil management. It comprises knowledge about SOM properties from different perspectives and their connection with the SOM biodegradability. The highly comple...

The sensitivity to temperature of soil organic matter (SOM) is receiving an increasing interest due to its importance in the global carbon (C) cycle and potential feedbacks to climate change. It constitutes a highly controversial topic in soil science due to different constrains involving the models employed, together with methodological limitation...

Wildfire has highly variable effects on soil, and different conservation strategies are required to address different levels of soil degradation. Rapid diagnosis of soil burn severity is required to enable the design of emergency post-fire rehabilitation treatments. This study evaluated whether visually different levels of soil burn severity (SBS)...

There is a great uncertainty about changes in soil organic carbon (SOC) and soil organic matter (SOM) caused by afforestation of pastures. Although the role of forest biomass and tree species on C sequestration has been solidly established, the effect on mineral soil is less known. Most of the works developed with that goal focus on quantification...

Aims Afforestation causes important alterations in SOM content and composition that affect the soil functions and C balance. The aim of this study was to identify the mechanisms that determine the changes in SOM composition following afforestation of grasslands. Methods The study included 4 chronosequences and 5 paired plots comprising pastures and...

Modelling SOM dynamics requires highly reproducible and accurate methods to monitor the evolution and changes in SOM nature of mineral soils caused by land use change. This is especially important when measuring the impact of soil management on C sequestration capacity in mineral soils. C sequestration in mineral soils depends not only on the balan...

Soil organic matter dynamics after land use change under contrasting climates

Important factors in the evaluation of fire severity are the duration of the soil exposition to a certain temperature as well as the factors that determine the thermal transmissivity on the soil (moisture, texture, organic matter content, etc.). The aim of this work was to apply the degree-hours method (DH) to characterize the thermal impact of for...

The microcalorimetric method was used to calculate the metabolic enthalpy change per mol of glucose degraded by soil microorganisms, ΔH met. This parameter has been calculated by microcalorimetry for many organic, inorganic and biochemical reactions, but there is only some information about its quantification for microbial growth reactions in soils...

The environmental concern on soil exploitation, linked to global warming by the Kyoto protocol, is responsible for increasing interest in the understanding of the role of the composition and structure of the soil organic matter (SOM) on soil carbon, C, dynamics. Thermal analysis and nuclear magnetic resonance (NMR) are applied to study the thermal...

The rational and sustainable exploitation of natural resources is one the priority objectives of our consumer society as an unavoidable strategy for survival. In previous articles, research group TERBIPROMAT has established the bases for the elaboration of energy maps of forest biomass. With those data, it is possible to classify the species in ter...

Characterizing soil metabolism requires measurement of the CO2 production rate or metabolic heat rate. While a single rate provides information on how rapidly substrates are being metabolized, the ratio of metabolic heat rate to CO2 production rate provides information on the nature of the substrates and the biochemical reactions taking place in th...

Soil carbon is the largest reservoir of organic carbon on the planet and CO2 production by soil thus has potentially large effects on atmospheric CO2. Carbon sequestration in soil is determined by the metabolic efficiency (substrate carbon conversion efficiency) of soil micro-organisms. That could be measured by calorespirometric methodology (paral...

Isothermal and Differential Scanning Calorimetry is applied to analyze the evolution of soil using its microorganisms and organic matter as bioindicators of soil quality. This study was carried out with two similar soils under different agricultural activities: culture and pasture. Sampling and measurements were performed through 1 year in order to...

The thermal and thermo-oxidative decompositions of NH4FePO4·H2O were studied by means of a combination of classical thermal analysis techniques (TG and DSC) with MS and powder XRD analysis. The experiment was run in two different (inert and oxidizing) atmospheres. In an inert (N2) atmosphere, thermal decomposition occurs in three steps at 265, 350...

A calorimetric procedure is developed to study the effect on the soil of the effluents resulting for the anaerobic digestion of slaughtering houses residues. DSC was used to study the pyrolysis properties of the effluent and the soil while isothermal calorimetry is applied to study the microbial activity in the effluent and to assess on its effect...

Differential scanning calorimetry was applied to assess on seasonally soil organic matter changes. Soils were collected in two sites located in Viveiro (Galicia, Spain). One of them has been used as arable land and the other one was under pinewood. Soil samples were seasonally collected during a year. The heat of combustion and the ignition tempera...

The Atacama desert in Chile is one of the driest and most lifeless environments on Earth. It rains possibly once a decade. NASA examined these soils as a model for the Martian environment by comparing their degradation activity with Martian soil and looking for “the dry limit of life”. The existence of heterotrophic bacteria in Atacama soil was dem...

The control on the CO2 coming from soil handling, makes necessary the introduction of new methodologies that inform about the capacity of the soil as a carbon sink and about the carbon decay. It can be performed through the microbial growth yield efficiency concept by calorimetry and enthalpy balances. Here it is examined the sensitivity of these i...

The microbial activity of Chromobacterium violaceum inoculated in sterile and natural red latosol soil samples was monitored by calorimetry to investigate metabolism of the native organic matter, easily degradable substrates (glucose) and the bacterial inhibitor m-alkoxyphenol. The results show that C. violaceum in sterile soil grows for a few hour...

Background and aims: In this study we have tried to identify subpopulations of obese subjects with some common pathogenetic features, which explain, at least in part, their overweight. Methods: We studied 75 healthy subjects (19 men and 56 women) with a different degree of overweight, initially divided in obese (BMI >= 30 kg/m(2)) and non-obese (BM...

The contribution of soil to the CO2 accumulated in the atmosphere and to global warming has given rise to the Kyoto protocol to consider the control on CO2 released by the land use. For this purpose, the Kyoto protocol advocates the introduction of new methodologies that can provide this information in a rational and ecological way. Here a thermody...

This paper is a review about the application of calorimetry to study soil properties and its metabolism. Although this research has increased slowly but continuously during the last 30 years, it is true that it has received poor attention. One reason for that could be the complexity of the soil and the difficulties to investigate it from a thermody...

Calorimetry was applied to develop a comparative study between the basal respiration and the degradation of an external carbon source in several soil samples. The main goals were to search for the connection between these reactions in soils and to test the sensitivity of calorimetric indices for the microbial activity. The soil samples were from th...

The fertilizer NH4FePO4·H2O (AIP) was synthesized under mild hydrothermal conditions to be applied on soils to prevent iron deficiencies. The effect of the addition of AIP on soil microbial activity was studied by calorimetry, determining both basal respiration and carbon mineralization by means of the addition of an external carbon source. Thermal...

The calculation of parameters involved in the kinetics of the microbial soil reactions linked to the carbon cycle is strongly limited by the methodologies employed. Hence, a mathematical model is proposed to quantify easily the specific rate of catabolic activity A(c) by microcalorimetry based on Belaich's model. It permits to quantify A(c) from th...

Microcalorimetry was applied to study the basal respiration in several soils collected in Galicia (Northwest Spain) and in the Brazilian Amazon. The microbial activity was recorded microcalorimetrically as power–time lines during 24h. The soil mass specific heat rate JQ/S and the cell specific heat rate JQ/N were calculated, and compared to the mic...

In this work, a method is proposed to quantify the efficiency of carbon utilization by soil microbes. Microcalorimetry was used to compute the heat yield (Y(Q/X)) of six soil samples collected in the Amazon. A combined mass and energy balance is developed to quantify the enthalpy of the glucose oxidation reaction (Delta(r)H(s)) and the biomass yiel...

The auditory perception of fricatives /f/ and /θ/ in the context of /e/ and /u/ was investigated for Hypo and Hyperspeech in four conditions: 1) Fricative noise; 2) Fricative noise + 51.2 ms of the following vowel; 3) Fricative noise + whole following vowel; 4) Whole word. The results show that in condition 1, /θ/ is equally recognized in both cont...

The auditory perception of fricatives /f/ and /theta/ in the context of /e/ and /u/ was investigated for Hypo and Hyperspeech in four conditions: 1) Fricative noise; 2) Fricative noise + 51.2 ms of the following vowel; 3) Fricative noise + whole following vowel; 4) Whole word. The results show that in condition 1, /theta/ is equally recognized in b...

Some soils collected in the Amazonian State of Brazil were studied in an attempt to interpret thermodynamically a growth reaction representing balanced exponential microbial growth. The aim is to calculate and to interpret the metabolic enthalpy change per mole of glucose catabolically consumed by soil microorganisms, ΔHmet, to explain the changes...

The perceptual interaction between the consonant and the vowel in fricative+vowel syllables is evaluated. A set of conflicting cue stimuli was used to measure the relative importance of: (a) the influence of the vowel in the previous consonant, and (b) the influence of the fricative in the following vowel. It is concluded that the perceptual intera...

Microcalorimetric method was applied to study some Amazonian soils in order to establish the way by which the microbial soil activity is affected by the actual deforestation and burning suffered by the Amazonian rain forest. Different soil samples were collected in the Amazonian State of Brazil. Places with autochthonal vegetation and places that w...

Microcalorimetry was applied to the study of the microbial activity of four soils with different percentages of organic matter. The qualitative study of the heat flow rate-time curves, recorded from soil samples amended with glucose, showed remarkable differences in the soil microbial activity. In order to show results in a more quantitative way, t...

Microcalorimetry has been used to study the effect of moisture on soil microbial activity. Different moisture regimes produce changes on heat flow rate-time curves recorded for soil samples, affecting also certain parameters, such as the total heat evolution Qtot, the microbial growth rate constant μ and growth yield Y, which are calculated by the...

The effect of the storage of soils on their microbial activity has been studied using a microcalorimetric method. Soil samples were kept in closed polyethene bags at 4°C during 3–6 months. Results show changes in the slope of the differentP−t curves recorded from the samples stored at 4°C. This fact strongly suggest the existence of changes of the...

Microcalorimetry was used to study the microbial degradation of glucose in soil. Relationships between heat evolution and the viable cell counts permit the quantification of kinetic parameters for microbial growth in soil, such as Monod's substrate constant, Ks = 1.62±0.08 mM, and the maximum microbial growth rate constant, μmax= 0.26±0.01 h−1.

A simple threshold-based method is described which permits automatic distinction between the Spanish fricatives [] and [s] in the initial position by means of a measurement of energy and a rough determination of the spectral composition as the zero-crossing rate. All signal analysis (including word endpoint and fricative detection; is carried out...

The binding constant and stoichiometry for the complexation of prednisone with β-cyclodextrin in aqueous solution, and the Gibbs energy for the transfer of β-cyclodextrin and prednisone from water to chloroform are reported. These data are used to evaluate, from the thermodynamic point of view, the influence of β-cyclodextrin on the transfer of pre...

Pichia stipitis is one of few yeasts capable of an efficient fermentation of pentoses to ethanol. This is a promising way to obtain ethanol from hemicellulose. In order to optimize the fermentation conditions for this process it is important to know the ethanol tolerance of the yeast. Here we report a microcalorimetric study of the inhibitory effec...

The inhibitory effects of ethanol on the fermentative activity of Pichia stipilis was studied by microcalorimetry. It was observed that the specific growth rate decreases when increases the level of ethanol in the culture medium.