Impacto de tratamentos térmicos en solos florestais afetados por incêndios de diferente severidade e recorrência

Thermal treatments in the laboratory were conducted using unburned and burned samples of two soils affected by low- or high severity fires in order to study their impact on forests ecosystems with different fire regimes (severity, recurrence). Soils samples were heated in a furnace for 15 minutes at 50 ºC, 75 ºC, 100 ºC, 125 ºC, 150 ºC, 175 ºC, 200 ºC and 300 ºC to simulate different fire intensities; the process was repeated after a 1 month incubation of the burned, rewetted samples in order to simulate fire recurrence. The soil temperature was measured with thermocouples at the surface and 1 cm depth. The maximum temperature reached (Tmax) and the amount of heat supplied to the samples (degree-hour, DH) were calculated from the temperature-time curves. A total of 128 temperature-time curves (4 soil field samples x 8 heating temperatures x 2 depths x 2 successive heat treatments) were analyzed and the estimation of several soil physical and chemical properties (color, moisture content, pH, total C, total N, soluble C) was carried out in the different soil treatments. High-severity burning provoked significant changes on these physical and chemical properties, whereas slight modifications or even no changes were due to low-severity burning or soil heating under laboratory conditions. The thermal properties exhibited a higher sensitivity for the detection of the fire regime impact than the physical and chemical properties. The results showed that the temperature-time curves and derived parameters (slope, Tmax, DH) can be successfully used to quantify the impact of thermal shocks at low and high temperatures and to evaluate the effect of fire/heating recurrence on forests ecosystems.Se realizaron, en condiciones de laboratorio, diversos tratamientos térmicos con muestras no quemadas y quemadas de dos suelos afectados por incendios de alta y baja severidad con el fin de determinar su impacto sobre ecosistemas forestales con diferente régimen del fuego (severidad y recurrencia). Las muestras se quemaron en una mufla durante 15 minutos a 50 ºC, 75 ºC, 100 ºC, 125 ºC, 150 ºC, 175 ºC, 200 ºC y 300 ºC para simular diferentes intensidades del fuego; tras un mes de incubación de las muestras quemadas e humectadas, se procedió a una segunda quema para simular la recurrencia del fuego. Se midió la temperatura del suelo con termopares en la superficie y a 1 cm de profundidad y, a partir de las curvas de temperatura-tiempo, se calcularon la temperatura máxima alcanzada (Tmax) y la cantidad de calor suministrada a la muestra (grados-hora, GH). Se analizaron un total de 128 curvas de temperatura-tiempo (4 muestras de suelo x 8 temperaturas de calentamiento x 2 profundidades x 2 tratamientos térmicos consecutivos) y se realizó la caracterización física y química (color, humedad, pH, C total, N total, C soluble en agua) de las muestras de suelo sometidas a los diferentes tratamientos térmicos. Las propiedades físicas y químicas experimentaron cambios significativos como consecuencia del incendio de alta intensidad y no se detectaron variaciones tras el impacto del incendio de baja severidad y del quemado del suelo en condiciones de laboratorio. Las propiedades térmicas mostraron una mayor sensibilidad que las propiedades físicas y químicas para detectar el impacto del régimen del fuego. Los resultados obtenidos demostraron que las curvas de temperatura-tiempo y los parámetros derivados (pendiente, Tmax, GH) pueden usarse satisfactoriamente para cuantificar el impacto del tratamiento térmico a bajas y altas temperaturas y para evaluar el efecto de la recurrencia del fuego/calentamiento en los ecosistemas forestales.Realizaram-se ensaios de laboratório com diferentes tratamentos térmicos em amostras queimadas e não queimadas de dois solos afetados por incêndios de alta e baixa severidade, para determinar o seu impacto em ecossitemas florestais sob diferente regime de fogo (severidade e recorrência). As amostras queimaram-se na mufla durante 15 minutos a 50 º C, 75 º C, 100 º C, 125 º C, 150 º C, 175 º C, 200 º C e 300 º C com o objectivo de simular diferentes intensidades de queima; após de um mês de incubação das amostras queimadas e umedecidas, foi feita uma segunda queima para simular a recorrência do fogo. A temperatura do solo foi medida com termopares na camada superior e a 1 cm de profundidade. A partir das curvas de temperatura-tempo, foi calculada a temperatura máxima alcançada (Tmax) e a quantidade de calor fornecida (graus-hora, DH). Analisaram-se um total de 128 curvas de temperatura-tempo (4 amostras de solo x 8 temperaturas de aquecimento x 2 profundidades x 2 tratamentos térmicos subsecutivos) e caracterizaram-se as propriedades físicas e químicas (color, umidade, pH, C total, N total, C solúvel em agua) das amostras de solo submetidas aos diferentes tratamentos térmicos. As propriedades físicas e químicas apresentaram alterações significativas com respeito à queima de alta intensidade e não foram detectadas variações após o impacto da queima de baixa severidade e também não no que diz respeito ao aquecimento do solo em condições de laboratório. As propriedades térmicas mostraram uma maior sensibilidade que as propriedades físicas e químicas para a deteccão do impacto do regime do fogo. Os resultados obtidos mostram que as curvas de temperatura-tempo e os parâmetros derivados (pendente, Tmax, DH) podem ser utilizados satisfatoriamente para a quantifição do impacto do tratamento térmico a baixas e altas temperaturas, e para avaliar o efeito da recorrência do fogo/aquecimento nos ecossistemas florestais.This study was supported by the Ministerio Español de Economía y Competitividad (AGL2012-39686-C02-01) and by Fundación MAPFRES

Soil Heating at High Temperatures and Different Water Content: Effects on the Soil Microorganisms

Soil properties determining the thermal transmissivity, the heat duration and temperatures reached during soil heating are key factors driving the fire-induced changes in soil microbial communities. The aim of the present study is to analyze, under laboratory conditions, the impact of the thermal shock (infrared lamps reaching temperatures of 100 °C, 200 °C and 400 °C) and moisture level (0%, 25% and 50% per soil volume) on the microbial properties of three soil mixtures from different sites. The results demonstrated that the initial water content was a determinant factor in the response of the microbial communities to soil heating treatments. Measures of fire impact included intensity and severity (temperature, duration), using the degree-hours method. Heating temperatures produced varying thermal shock and impacts on biomass, bacterial activity and microbial community structureThis research was funded by Spanish Ministry of Economy and Competitiveness (AGL2012-39686-C02-01) and for the for the MAPFRE foundation. A. Barreiro and A. Lombao are recipients of FPU grant from Spanish Ministry of EducationS

Estudo a escala de microcosmos de barreiras reativas permeáveis com serragem de granito e composto para o tratamento de água contaminadas com Cr (VI)

The permeable reactive barrier (PRB) is a technology developed for the removal of contaminants in groundwater. It consists of a screen perpendicular to the flow of contaminated groundwater filled with a material capable of adsorbing, precipitating or degrading pollutants. Several materials have been tested for their use as reactive substrates for the construction of PRBs. Waste materials are of particular interest for this purpose due to the possibility of their reuse and their generally lower cost. With this aim, the Cr (VI) retention capacity of filler material consisting either of pine bark compost (PB) or a 50% mixture of compost and granite powder (PB50) was evaluated using an experimental device specifically designed for this study, which reproduces a permeable reactive barrier at the laboratory scale. Percolation experiments were carried out with a solution of 100 mg L-1 Cr (VI) in 0.01M KNO3, followed by a leaching step with the saline background. The results show that compost is a highly efficient filler for permeable reactive barriers with almost 100% retention of Cr, whereas the retention efficiency of the mixture of PB50 oscillated between 18 and 46% during the experiment. The Cr retained by the filling material is strongly fixed, since no desorption was detected by leaching with the saline background, and concentrations in the standard Toxic Characteristic Leaching Procedure (TCLP) extracts were lower than 1 mg L-1. This behaviour minimizes the risk of release of the Cr retained by the material of the barrier in the event of it being traversed by water not contaminated with Cr. Modelling with Visual Minteq indicates that in the experiments with PB, the reduction of Cr (VI) to Cr (III) occurs and that Cr (III) is associated with dissolved organic matter, which is a form of lower toxicity than the initial Cr (VI) species. In turn, in the experiments with PB50, Cr (III) and Cr (VI) coexist and the oxidised form is not associated with dissolved organic matter, which suggests greater toxicity. The results indicate that pine bark compost is a potential candidate for use as filler material permeable reactive barriers.Las barreras permeables reactivas (BPRs) son tecnologías de eliminación de contaminantes en aguas subterráneas, que consisten en una pantalla perpendicular al flujo de agua subterránea contaminada, rellena de un material con capacidad de adsorber, precipitar o degradar los contaminantes. Se han evaluado diversos materiales reactivos como material de relleno de BPRs, siendo de especial interés la utilización de materiales residuales, por la posibilidad de su reutilización y, frecuentemente, menor coste. Con este fin se estudió la capacidad de retención de Cr (VI) de compost de corteza de pino (PB) y de una mezcla al 50% de compost y serrines graníticos (PB50), utilizando un dispositivo diseñado específicamente para este estudio, que reproduce una barrera permeable reactiva a escala de laboratorio. Para evaluar la retención se llevó a cabo un experimento de percolación con una disolución de 100 mg L-1 de Cr (VI) en KNO3 0,01M, seguido de una etapa de lavado con el fondo salino, para evaluar la liberación del Cr previamente retenido. Los resultados mostraron una gran eficacia del compost como material de relleno de BPRs, consiguiendo una retención de Cr cercana al 100%. La mezcla de serrín granítico y compost presentó una capacidad de retención que osciló entre el 18 y el 46% a lo largo del experimento. El Cr retenido por el material de relleno se encuentra fuertemente fijado, pues no se desorbe por lixiviación con la solución salina y las concentraciones en los extractos obtenidos mediante la aplicación del procedimiento estándar de lixiviación Toxic Characteristic Leaching Procedure (TCLP) fueron inferiores 1 mg L-1. Este comportamiento minimiza el riesgo de liberación del Cr retenido por el material de la barrera, en el supuesto de que fuera atravesada por un agua no contaminada con Cr. La modelización con Visual Minteq indica que, en los eluatos de los experimento con PB, se ha producido reducción de Cr (VI) a Cr (III), y éste se encuentra asociado con la materia orgánica disuelta, lo que sugiere una reducción de la toxicidad en comparación con la que presenta el Cr (VI) introducido en la solución de percolación. En los eluatos del experimento con PB50 se encuentran tanto Cr (III) como Cr (VI), y la forma oxidada no se encuentra asociada con la materia orgánica disuelta. Los resultados de este estudio indican que el compost de corteza de pino tiene un gran potencial para ser usado como material de relleno de barreras permeables reactivas.Entre as tecnologias desenvolvidas para a remoção de contaminantes em águas subterrâneas são as barreiras permeáveis reactivas (BPRs), as quais consistem de uma trincheira perpendicular ao fluxo das águas subterrâneas contaminadas, cheia com um material capaz de adsorver, precipitar ou degradar poluentes. Diversos matérias foram ensaiados como substratos reativos na construção de BPRs, sendo de interesse a utilização de materiais residuais, pela possibilidade de reutilização e, geralmente, menor custo. Para este fim foi avaliada a capacidade de retenção de Cr (VI) de um composto de casca de pinheiro (PB) ou uma mistura de 50% de composto e pó de serragem de granito (PB50), usando um dispositivo experimental que simula uma barreira permeável reactiva a escala de laboratorio. Experiências de percolação foram levadas a cabo com uma solução de 100 mg L-1 de Cr (VI) em 0,01MKNO3, seguida por um passo de lavagem com a solução salina. Os resultados obtidos mostram uma alta eficáciado composto, com uma retenção de 100% de Cr. A eficiência de retenção da mistura de serradura de grantito e de composto oscilou entre 18-46% ao longo do experimento. O Cr é fortemente retido pelo material de enchimento, não dessorvido por lixiviação com a solução salina, enquanto que as concentrações dos extractos obtidos pela aplicação do procedimento de lixiviação standar Toxic Characteristic Leaching Procedure (TCLP) eram inferiores a 1 mg L-1. Este comportamento reduz o risco de a liberação da carga de Cr retida pelo BPR o que poderia acontecer se águas limpas passan através da barreira. O modelado com Visual Minteq indica que nas experiências com PB ocorre redução de Cr (VI) a Cr (III), e que o Cr (III) está associado com a matéria orgânica dissolvida, que é uma forma de toxicidade mais baixa do que as espécies de Cr (VI) iniciais, enquanto nas experiências com PB50, Cr (III) e Cr (VI) coexistem, e o Cr (VI) não está associado com a matéria orgânica dissolvida, o que sugere uma maior toxicidade. Os resultados indicam que o composto de casca de pinheiro é um candidato potencial para utilização como material de enchimento de barreiras permeáveis reactivas.The study was funded by the Xunta de Galicia through the project entitled Avaliación do uso de materiais de caracter inerte e orgánico para o tratamento de augas contaminadas –Tradesol (09MDS005CT). The authors also thank Xunta Galicia-Feder for the financial support through "Axudas de Consolidación e Estruturación de Unidades de Investigación Competitivas. IN845B-2010/038 and GRC2014/028". Diego Martiñá Prieto wishes to acknowledge the financial support of the Spanish Ministry of Economy and Competitiveness for his FPI Fellowship (BES-2011-044514)S

Incendios forestales y salud pública

This paper reviews the articles that deal with the public health issues caused by forest fires between 1990 and 2018. The main polluting products and the key processes that give rise to them are highlighted. The transport processes and the risk exposure for population are analysed. This review mainly looks into their impact on mortality, respiratory and cardiovascular morbidity as well as other possible impacts on human health. Apart from the risks generated by air pollution, the impact of forest fires on soil and water pollution and on human health are emphasized. This last issue has not been thoroughly analysed yet. Finally, the relevance of these issues is shown despite the lack of researches in the European area.Se realiza una revisión de los trabajos que estudian los problemas de salud pública generados por los incendios forestales desde 1990 hasta 2018. Se destacan los principales productos contaminantes implicados así como los procesos fundamentales que los originan. Se analizan sus procesos de transporte así como los riesgos de exposición de la población, destacando aquellos colectivos más sensibles. La revisión analiza sobre todo su influencia sobre la mortalidad, morbilidad respiratoria y cardiovascular, así como otras posibles influencias sobre la salud humana. Además de los riesgos generados por la contaminación atmosférica se pone de manifiesto la influencia de los incendios forestales en la contaminación del suelo y el agua y su posible repercusión sobre el bienestar humano, cuestión hasta ahora poco estudiada. Finalmente se pone de manifiesto la importancia que esta problemática está adquiriendo en los últimos años si bien sus estudios son relativamente escasos en el área europea

Lixiviação de Al e Fe em solos sumetidos a queimadas controladas em laboratório

The influence of the severity of soil heating on aluminium and iron leaching was analysed, as well as its relationship with the solubility of organic matter. For this purpose, laboratory experiments were carried out under microcosm conditions where unaltered soil blocks were submitted to thermal shock and subsequently to rainfall simulation (300 mm), collecting the surface (0 cm) and subsurface runoff (12 cm). Soil heating was carried out using infrared lamps reaching temperatures of 222 and 401 ºC at a depth of 1 cm, similar to those reached in moderate and high intensity fires respectively. The analysis of the drainage waters showed that the leaching of Al increased with the severity of the thermal shock, whereas for Fe perceptible effects were only seen at the highest temperature. Geochemical modelling with Visual MINTEQ indicated that Al and Fe were fundamentally mobilised and associated with dissolved organic matter. Weak interactions (electrostatic binding) predominated in the case of Al and strong interactions (bidentate complexes with dissolved organic matter) in the case of Fe. Only towards the end of the leaching experiment, when the concentration of dissolved organic carbon decreased, was there a perceptible mobility of Al and Fe in the inorganic form, in the subsurface leachate of the moderate temperature treatment.Se analizó la in!uencia de la severidad del calentamiento del suelo en la lixiviación de aluminio y hierro, y su relación con la solubilidad de la materia orgánica. Para tal fin, se realizaron experimentos de laboratorio, en condiciones de microcosmos, en los que bloques de suelo inalterados fueron sometidos a choques térmicos y posteriormente a la acción de lluvia simulada (300 mm), recogiendo las aguas de escorrentía superficial (0 cm) y subsuperficial (12 cm). El calentamiento del suelo se llevó a cabo por medio de lámparas infrarrojas, que permitieron alcanzar temperaturas de 222 y 401 ºC, a 1 cm de profundidad, similares a las que se alcanzan, respectivamente, en incendios de severidad moderada y alta. El análisis de los lixiviados mostró que el lavado de Al aumentó con la severidad del choque térmico, mientras que para el Fe solo se observaron efectos apreciables para la temperatura más alta. La modelización geoquímica con el programa Visual Minteq indicó que Al y Fe se movilizaron fundamentalmente asociados a materia orgánica disuelta, redominando las uniones débiles (enlace electrostático) en el caso del Al y las uniones fuertes (complejos bidentados con la materia orgánica disuelta) en el caso del Fe. Únicamente hacia el final del experimento de lixiviación, cuando disminuyó la concentración de carbono orgánico disuelto, se observó una movilización apreciable de Al y Fe en forma inorgánica en el lavado subsuperficial del tratamiento de moderada temperatura.Analisou-se a influência da severidade do aquecimento do solo na lixiviação do alumínio e do ferro, bem como a sua relação com a solubilidade da matéria orgânica. Assim, realizaram-se ensaios laboratoriais desenvolvidos em microcosmos, com blocos de solo não alterados submetidos a choques térmicos e seguidamente a testes de chuva simulada (300 mm). Recolheram-se as águas de escorrimento superficial (0 cm) e subsuperficial (12 cm). O aquecimento do solo foi feito com lâmpadas de infravermelho atingindo temperaturas de 222 e 401 ºC a 1 cm de profundidade, à semelhança das alcançadas em incêndios forestais de média e alta intensidade. A análise dos lixiviados mostrou que a lixiviação do Al aumenta com a severidade do choque térmico, enquanto que no caso do ferro apenas foram percetíveis efeitos para a temperatura mais elevada A modelagem geoquímica com o programa Visual Minteq, indicou que o Al e o Fe sofrem mobilização em associação com a matéria orgânica dissolvida, com o predomínio de interações fracas (ligação eletrostática) no caso do Al e de interações fortes (complexos bidentados com matéria orgânica dissolvida) no caso do Fe. Apenas no fim do ensaio de lixiviação, quando as concentrações carbono orgânico dissolvido diminuem, ocorre mobilização apreciável de Al e Fe na forma inorgânica no lixiviado subsuperficial do tratamento da temperatura média.S

Impact of Herbicide Treatments on the Construction Materials in the Roman Wall of Lugo, Spain (UNESCO World Heritage Site)

Combined laboratory and field research examining the possible alterations caused by herbicide treatments applied to the construction materials (schist and some granite, bound with mortar) in the Roman wall of Lugo (NW Spain), declared a World Heritage site by UNESCO in 2000, was performed in three separate studies in the past 20 years. In the summers of 1998 and 1999, the herbicides glyphosate, sulphosate and glufosinate–ammonium, as well as physical treatments (infrared and burning) were separately applied to different areas of the wall. In the spring of 2016, the oxyfluorfen herbicide Goal Supreme® was applied to test areas. In the winter of 2018, three essential oils, Origanum vulgare L., Thymus zygis Loefl. ex L., and Thymus vulgaris L., were each applied to test areas. Mineralogical modifications in the materials (determined by X-ray diffraction analysis), as well as visible physical changes, such as colour changes, and the appearance of saline residues were evaluated after the treatments. In the 1998/9 trial, glyphosate and both physical treatments triggered changes in the vermiculite clay minerals in the schists, and the physical treatments also caused changes in the kaolinite. None of the treatments caused highly perceptible colour changes. The oxyfluorfen herbicide did not cause any mineralogical alterations in the construction materials, but it did generate an increase in chloride, nitrate and sulphate contents of the granite and a slight darkening of this material. In the most recent study, the only deleterious effect observed was a perceptible increase in lightness and reduction in the yellow component after the application of Thymus zygis Loefl. ex L. essential oil to graniteThe results of the different studies presented here were financially supported by the following contracts: “Evaluación de diferentes métodos de control de las malas hierbas de la muralla de Lugo. Xunta de Galicia. Consellería de Cultura, Comunicación Social e Turismo. 1998 and 1999”; “Seguimiento de los tratamientos de control de la flora vascular en la muralla romana de Lugo. Restauraciones y Construcciones Luis J. Sánchez SA. 2015–2017”; “Realizar el seguimiento del segundo tratamiento fitosanitario 2017 y realizar un ensayo de herbicidas naturales en las paredes da muralla. Restauraciones y Construcciones Luis J. Sánchez SA. 2017–2018”; “Realizar el seguimiento de la limpieza manual de las paredes de la muralla romana de Lugo en el verano-otoño de 2019 y la aplicación en las paredes de la muralla romana de Lugo de herbicidas naturales potenciales para controlar la germinación de Parietaria Judaica L. Restauraciones y Construcciones Luis J. Sánchez SA. 2019–2020”. The authors are also grateful for financial support from the Xunta de Galicia (grant ED431C 2018/32)S

Derivation and validation of a clinical prediction rule for sleep apnoea syndrome for use in primary care

Background: Several clinical prediction rules (CPRs) are available for sleep apnoea-hypopnoea syndrome (OSAH), but they are difficult to apply in primary care (PC). Aim: Derivation and validation of a CPR using simple measurements available in PC. Design & setting: A prospective study conducted in health centres from the area of influence of three Spanish hospitals. Method: Patients (aged 18-70 years) who attended for any reason; who presented with at least one of the three key symptoms for OSAH (snoring, breathing pauses while sleeping, and daytime sleepiness); and who were not undergoing non-invasive ventilation or prior treatment with continuous positive airway pressure (CPAP) were included. Anthropometric data, smoking habit, comorbidities, and Epworth test were collected. Patients were subsequently referred to the sleep unit (SU), where the decision was taken whether or not to instigate treatment. A multivariate logistic model was constructed using a sub-sample and scores assigned based on the regression coefficients; the CPR was validated with the remaining sample. Both receiver operating characteristic (ROC) curves were plotted and the sensitivity, specificity, and predictive values calculated. Results: The derivation sample comprised 352 patients, with 260 in the validation sample. The final factors (arterial hypertension [AHT], age, body mass index [BMI], and sex) were used to develop a rule with scores ranging from 0.00-5.50. The cut-off point that optimises the area under the curve (AUC) is ?2.50 points (AUC = 0.78; sensitivity = 86%; specificity = 54%; positive predictive value [PPV] = 45%; negative predictive value [NPV] = 90%; likelihood ratio [LR] = 0.26). The properties for the validation sample with this cut-off point are as follows: AUC = 0.68; sensitivity = 81%; specificity = 43%; PPV = 61%; NPV = 68%; LR = 0.44. Conclusion: As in similar cases, the specificity is low, meaning that healthy people are referred to a specialist. A negative result rules out the disease in most cases

The jaguarondi, Herpailurus yagouaroundi (Carnivora: Felidae) in Uruguay: historical account and current situation

La presencia del yaguarundí, Herpailurus yagouaroundi (É.Geoffroy Saint-Hilaire, 1803) en Uruguay ha sido controversial. Sistematizamos sus registros y analizamos menciones históricas y recientes. Existen varios reportes en los siglos XIX y XX, aunque sin evidencia material. Eso llevó a excluirlo de la mastofauna uruguaya entre 1972 y 2016, año este último en que fue documentado mediante cámaras trampa. La información nacional y regional sugiere que, en la actualidad y probablemente en el pasado, se han registrado en Uruguay dos morfos de pelaje (oscuro y rojizo). Sería una especie escasa y posiblemente amenazada y se necesitan más estudios para determinar su estado de conservación en el país.The presence of the jaguarondi, Herpailurus yagouaroundi (É. Geoffroy Saint-Hilaire, 1803) in Uruguay has been controversial.We systematized its records and analyzed historical and current mentions. There have been reports in the 19th and 20th centuries, although without material evidence. This led to the species not being considered among the native fauna between 1972 and 2016 when it was finally documented with camera traps. The information at national and regional levels suggests that currently and probably in the recent past, two pelage variants (grey and reddish) were recorded in Uruguay. Albeit it is scarce and possibly endangered in Uruguay, more studies are needed to assess the conservation status in the country