Revista Internacional de Contaminación Ambiental
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PRODUCTION OF MEDIUM CHAIN LENGTH POLYHYDROXYALKANOATES FROM Cupriavidus necator WITH BEESWAX HYDROLYZATES AS CARBON SOURCE
Get PDFThis study demonstrates that using beeswax hydrolyzates (Hw), short- or medium-chain-length polyhydroxyalkanoates (scl-mcl-PHA) can be obtained by a three stages fed-batch fermentation system. The fed batch fermentations were conducted with a strain of Cupriavidus necator. Glucose and ammonium sulphate as carbon and nitrogen sources, respectively, were used in a first and second culture stages. In the third stage (production of scl-mcl-PHA) a fresh medium was fed with Hw as a carbon source at a concentration of 5 g/L, obtaining 8.91 g/L of intracellular scl-mcl-PHA and 13.64 g/L of biomass, which resulted in 65.3 % w/w of scl-mcl-PHA. Using nuclear magnetic resonance, the presence of scl and mcl monomers, 3-hydroxybutyrate (3HB) and 3-hydroxydecanoate (3HD) was determined. The percentage of comonomer incorporation different to 3HB was 4.6 mol %. A glass transition temperature (Tg) of –50 ºC and a melting temperature (Tm) of 79.8 ºC were determined for the scl-mcl-PHA (3HB-co-3HDD).This study demonstrates that using beeswax hydrolyzates (Hw), short- or medium-chain-length polyhydroxyalkanoates (scl-mcl-PHA) can be obtained by a three stages fed-batch fermentation system. The fed batch fermentations were conducted with a strain of Cupriavidus necator. Glucose and ammonium sulphate as carbon and nitrogen sources, respectively, were used in a first and second culture stages. In the third stage (production of scl-mcl-PHA) a fresh medium was fed with Hw as a carbon source at a concentration of 5 g/L, obtaining 8.91 g/L of intracellular scl-mcl-PHA and 13.64 g/L of biomass, which resulted in 65.3 % w/w of scl-mcl-PHA. Using nuclear magnetic resonance, the presence of scl and mcl monomers, 3-hydroxybutyrate (3HB) and 3-hydroxydecanoate (3HD) was determined. The percentage of comonomer incorporation different to 3HB was 4.6 mol %. A glass transition temperature (Tg) of –50 ºC and a melting temperature (Tm) of 79.8 ºC were determined for the scl-mcl-PHA (3HB-co-3HDD)
TOXICOKINETIC AND TOXICODYNAMIC SYMBIOTIC INTERACTIONS AMONG INTESTINAL Pseudomonas DEGRADING OF HYDROCARBONS WITH ITS WILD HOST FISH Chirostoma jordani
Get PDFThe symbiotic relationship between native microbiota and their hosts probably is a key factor in animal survival. In this study, the relationships of Pseudomonas spp. strains with specific biomarkers of exposure to polycyclic aromatic hydrocarbons (PAHs) in wild fish Chirostoma jordani, as well as the capacity of these bacteria to biotransform PAHs were evaluated. The activity of the naphthalene dioxygenase system of the bacteria exposed to 0.1, 1.0 and 10 µg/L of PAHs was higher than the mean isoform 1A1 (CYP1A1) of the wild fish, particularly bacterial species related to Pseudomonas spp. However, the epoxide hydrolase activity of the strains was lower in all cases compared to the fish. Glutathione S-transferase (GST) activity of the bacterial strains was lower than in the liver, but higher than in viscera of C. jordani. Using redundancy analysis, two differential patterns were found: (i) CYP1A1 activity of fish was induced by naphthalene and anthracene water levels independently of sampling season and lakes monitored, and (ii) the unidentified strain of the Pseudomonas genus biotransforms the endogenous levels of benzo[a]pyrene, benzo[k]fluoranthene and indeno[1,2,3-cd]pyrene in the fish allowing the hydroxylated metabolites to conjugate with glutathione through GST activity of the fish.The symbiotic relationship between native microbiota and their hosts probably is a key factor in animal survival. In this study, the relationships of Pseudomonas spp. strains with specific biomarkers of exposure to polycyclic aromatic hydrocarbons (PAHs) in wild fish Chirostoma jordani, as well as the capacity of these bacteria to biotransform PAHs were evaluated. The activity of the naphthalene dioxygenase system of the bacteria exposed to 0.1, 1.0 and 10 µg/L of PAHs was higher than the mean isoform 1A1 (CYP1A1) of the wild fish, particularly bacterial species related to Pseudomonas spp. However, the epoxide hydrolase activity of the strains was lower in all cases compared to the fish. Glutathione S-transferase (GST) activity of the bacterial strains was lower than in the liver, but higher than in viscera of C. jordani. Using redundancy analysis, two differential patterns were found: (i) CYP1A1 activity of fish was induced by naphthalene and anthracene water levels independently of sampling season and lakes monitored, and (ii) the unidentified strain of the Pseudomonas genus biotransforms the endogenous levels of benzo[a]pyrene, benzo[k]fluoranthene and indeno[1,2,3-cd]pyrene in the fish allowing the hydroxylated metabolites to conjugate with glutathione through GST activity of the fish
CARACTERIZACIÓN QUÍMICA Y FÍSICA DEL BAGAZO DE AGAVE TEQUILERO COMPOSTADO CON BIOSÓLIDOS DE VINAZA COMO COMPONENTE DE SUSTRATOS PARA CULTIVOS EN CONTENEDOR
Get PDFThe objectives of this study were to determine the chemical and physical properties of tequila blue agave bagasse composted with tequila vinasses’ biomass (compost) in coconut based powder substrates for potted plants and to compare their performance against two commercial substrates. The substrates evaluated included coconut powder, Canadian peat, 100 % compost, and 3-coconut powder based mixtures containing 30 %, 50 %, and 70 % compost. Chemical parameters analyzed comprise organic matter, pH, conductivity, cation exchange capacity, total organic carbon, C/N ratio, total nitrogen, phosphorus, potassium, and magnesium. The physical properties evaluated included apparent density, apparent specific density, total porous spaces, free water, bound water, absorbed water and particle size distribution. We were able to demonstrate that the formulations of agave bagasse compost and coconut powder could replace coconut powder and peat, since their physical and chemical characteristics are suitable for its use as substrate for plants cultivated in containers. The treatments with better results were those with 30 %, 50 %, and 100 % compost. Composting waste materials provide additional benefits including a reduction in environmental pollution as well as the local production of substrates for protected agriculture systems, which require substantial quantities of these type of materials. El presente estudio tuvo como objetivo caracterizar las propiedades químicas y físicas del bagazo de agave tequilero compostado con biosólidos de vinaza en formulaciones con polvo de coco, para compararlas con sustratos comerciales utilizados para cultivos en contenedor, con el fin de valorar el potencial de aprovechamiento de los dos desechos más importantes de la industria tequilera. Los sustratos evaluados fueron polvo de coco, turba canadiense, mezclas de polvo de coco con tres niveles de composta: 30 %, 50 % y 70 % (v/v), y composta 100 %. Los factores químicos a analizar fueron: materia orgánica, pH, conductividad eléctrica, capacidad de intercambio catiónico, carbono orgánico total, relación C/N, nitrógeno total, fósforo, potasio y magnesio; las físicas fueron: densidad aparente, densidad real, espacio poroso total, agua fácilmente disponible, agua de reserva, agua total disponible y distribución del tamaño de partículas. Se pudo demostrar que las formulaciones de compost de bagazo de agave con polvo de coco podrían reemplazar el uso de polvo de coco y turba, ya que poseen características químicas y físicas satisfactorias para ser utilizadas como sustratos para plantas cultivadas en contenedor. Los tratamientos mejor evaluados fueron compost 30 %, 50 % y 100 %. El aprovechamiento de los desechos compostados podría traer consigo otros beneficios, tales como la reducción de la contaminación ambiental a través de la producción local de sustratos destinados al sector de los cultivos protegidos, el cual tiene una demanda cada vez más creciente de estos materiales
ACTIVIDAD ACETILCOLINESTERASA (AChE) Y BUTIRILCOLINESTERASA (BUChE) EN POBLACIONES MEXICANAS: ESTUDIO PILOTO
Get PDFThe analytical determination of acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) activities is widely used in biological biomonitoring to evaluate exposure and detrimental effects caused by anticholinesterasic compounds. Nevertheless, a wide variability in values within the range considered as normal has been reported, which could be due to different factors. One of the most influencing factors on the variability of the data is the lack of standardized analytical and preanalytical parameters. The aim of this work was to know, under a consensual methodology, the intervals of AChE and BuChE activities in individuals non-occupationally exposed to anticholinesterase compounds from different states of the Mexican republic. From the participating laboratories, 22% reported values of AChE activity within the range considered as normal, whereas 67% reported values of BuChE activity within the range in a non-exposed population to anticholinesterase compounds. The results revealed an important variability in the values for AChE and BuChE activities, which show the need for continuous training among analysts and the homogenization of methodologies.La determinación de las actividades acetilcolinesterasa (AChE) y butirilcolinesterasa (BuChE) es ampliamente utilizada en estudios de monitoreo biológico para evaluar la exposición a compuestos anticolinesterásicos y sus efectos. No obstante, se ha observado una amplia variabilidad en los valores considerados como normales para estas actividades enzimáticas, lo que puede deberse a diversos factores. Uno de los que puede tener más influencia es la falta de parámetros preanalíticos y analíticos estandarizados. En este sentido, el objetivo de este trabajo fue conocer, con una metodología consensuada, los intervalos de las actividades AChE y BuChE en individuos no expuestos ocupacionalmente a compuestos anticolinesterásicos en diferentes estados de la república mexicana. Se observó que el 22 % de los laboratorios participantes reportaron valores de actividad AChE dentro del rango considerado como normal. Respecto a la actividad BuChE, el 67 % reportó valores dentro del rango para una población no expuesta a compuestos anticolinesterásicos. Los resultados revelaron una importante variabilidad en los valores de las actividades AChE y BuChE, que muestran la necesidad de capacitación continua entre los analistas y la homogeneización de las metodologías
“THERE’S A LOT OF CANCER HERE…” ENVIRONMENTAL RISK PERCEPTION AND MORTALITY AMONG WOMEN WHO LIVE IN AN INDUSTRIAL CORRIDOR IN MEXICO. A SEQUENTIAL MIXED STUDY
Get PDFThe objectives of this study were to characterize the environmental risks attributed to the Quetzalcóatl industrial corridor and to compare the records as opposed to the perceptions of increased mortality among community residents. A sequential mixed method design was used. Women in the community closest to the industrial corridor reported more respiratory disorders and more cases of cancer. They also referred to having been fearful during pregnancy because of a history in the community of premature births. From 2005 to 2007, the mortality rate for working-age women with cancer in the community closest to the corridor was significantly higher than the national rate (p < 0.05). An increase in the number of newborn deaths was observed in 1998 and 2000, with rate ratios of 5.8 (CI 3.1-6.9) and 2.9 (CI, 1.2-4.2), respectively. The integrated analysis of the qualitative and quantitative information enabled us to identify a correspondence between social perception of risk from industrial pollution and mortality registered in the study area. The experience of foul odors, the observation of increased cases of cancer and socio-cultural factors contribute to a perceived increased risk by women in the community closer to the industrial corridor. These results have implications for environmental policies in the industrial corridor, particularly with regard to risk mitigation and communication.The objectives of this study were to characterize the environmental risks attributed to the Quetzalcóatl industrial corridor and to compare the records as opposed to the perceptions of increased mortality among community residents. A sequential mixed method design was used. Women in the community closest to the industrial corridor reported more respiratory disorders and more cases of cancer. They also referred to having been fearful during pregnancy because of a history in the community of premature births. From 2005 to 2007, the mortality rate for working-age women with cancer in the community closest to the corridor was significantly higher than the national rate (p < 0.05). An increase in the number of newborn deaths was observed in 1998 and 2000, with rate ratios of 5.8 (CI 3.1-6.9) and 2.9 (CI, 1.2-4.2), respectively. The integrated analysis of the qualitative and quantitative information enabled us to identify a correspondence between social perception of risk from industrial pollution and mortality registered in the study area. The experience of foul odors, the observation of increased cases of cancer and socio-cultural factors contribute to a perceived increased risk by women in the community closer to the industrial corridor. These results have implications for environmental policies in the industrial corridor, particularly with regard to risk mitigation and communication
TEMPORAL VARIABILITY OF MERCURY EMISSIONS FROM A COAL-FIRED POWER PLANT IN MEXICO
Get PDFAccording to the Minamata Convention it is necessary to determine the mercury emissions from coal-fired power plants in Mexico due to Mexico’s responsibility to reduce its mercury emissions into the atmosphere. For this purpose, we used the coal consumption data provided directly by the Federal Electricity Commission of Mexico, which include emissions per day and per generating unit for the year 2013. To determine the mercury emissions from a coal-fired power plant in Mexico, we used the US Environmental Protection Agency methodology and focused on the Presidente Plutarco Elías Calles (CETEPEC) power plant, because in Mexico there are no methodologies to determine mercury emissions from coal-fired power plants. The results show that mercury emissions from units 1 to 6 of the CETEPEC plant range from 0.5 to 1.2 kg/day; however, emissions from unit 7 are as high as 2 kg/day. The total mercury emissions from the CETEPEC power plant in 2013 were 1942 kg, of which 1698 kg were gaseous elemental mercury (Hg0), 243 kg gaseous oxidized mercury (Hg2+), and 1.2 kg particle-bound mercury (Hgp). This study is relevant in Mexico and indicates an advance on the control of mercury emissions from the CETEPEC power plant, in accordance to the Minamata Convention.According to the Minamata Convention it is necessary to determine the mercury emissions from coal-fired power plants in Mexico due to Mexico’s responsibility to reduce its mercury emissions into the atmosphere. For this purpose, we used the coal consumption data provided directly by the Federal Electricity Commission of Mexico, which include emissions per day and per generating unit for the year 2013. To determine the mercury emissions from a coal-fired power plant in Mexico, we used the US Environmental Protection Agency methodology and focused on the Presidente Plutarco Elías Calles (CETEPEC) power plant, because in Mexico there are no methodologies to determine mercury emissions from coal-fired power plants. The results show that mercury emissions from units 1 to 6 of the CETEPEC plant range from 0.5 to 1.2 kg/day; however, emissions from unit 7 are as high as 2 kg/day. The total mercury emissions from the CETEPEC power plant in 2013 were 1942 kg, of which 1698 kg were gaseous elemental mercury (Hg0), 243 kg gaseous oxidized mercury (Hg2+), and 1.2 kg particle-bound mercury (Hgp). This study is relevant in Mexico and indicates an advance on the control of mercury emissions from the CETEPEC power plant, in accordance to the Minamata Convention
Editorial
Get PDFLa Red Temática de Toxicología de Plaguicidas, del CONACyT, reúne la experiencia y tenacidad de investigadores adscritos a importantes instituciones de investigación en México, así como a estudiantes de posgrado que se encuentran en formación dirigidos por dichos investigadores. La Red tiene como objetivo incentivar su conectividad, para abordar desde una perspectiva multidisciplinaria, interinstitucional y articulada, el problema complejo de los plaguicidas, lo cual contribuye en la consolidación del capital humano, el desarrollo de la Ciencia, la Tecnología e Innovación, en un tema prioritario para México.Como parte de los trabajos de la Red, se han realizado reuniones, talleres y simposios, como ejes estratégicos para la actualización de la información, el fortalecimiento y consolidación de la colaboración entre grupos, así como la publicación de artículos científicos, entre otros. En este contexto, la Red Temática unió esfuerzos con el grupo editorial de la Revista Internacional de Contaminación Ambiental, para la publicación del Número Especial de Contaminación y Toxicología de Plaguicidas, en el que algunos miembros de sus difunden la información que han generado en México relacionada con esta temática.Se recibieron 23 trabajos originales, de los cuales siete se publican en este primer número especial. En estos: González et al., abordan el efecto del glifosato de amonio sobre el ADN y la calidad espermática en ratones; Flores-Sánchez et al., realizan un monitoreo de niveles de plaguicidas organoclorados en toninas y manatíes en el sur del Golfo de México; García-Hernández et al., realizaron una revisión exhaustiva de 390 artículos publicados en México en los últimos 20 años, relacionados con el padrón y uso, presencia en el ambiente así como en alimentos, exposición y toxicología de plaguicidas, así como aspectos de biorremediación y bioplaguicidas; Benitez-Trinidad et al., dan a conocer el padrón actual de plaguicidas empleados en actividades de fumigación en el estado de Nayarit, y los efectos de los plaguicidas sobre diferentes actividades enzimáticas; López-Martínez et al., realizan un acercamiento exploratorio para conocer los diferentes aspectos socioeconómicos y culturales que implican el uso y manejo de plaguicidas en dos comunidades indígenas del estado de Nayarit; Romero et al., en su revisión analizan las técnicas de extracción, limpieza y cuantificación de endosulfán por métodos cromatográficos en matrices alimentarias en artículos publicados en los últimos 20 años; y por último Sánchez-Alarcón et al., analizan el daño al ADN causado por el herbicida MarvelÒ, un producto comercial a base de dicamba y atrazina como ingredientes activos a través de la prueba de micronúcleos empleando a Vicia faba como bioensayo.En estos trabajos se ve reflejada la multidisciplinariedad de los enfoques con los que se aborda la problemática de los plaguicidas en México y la colaboración de los miembros de la Red.La Red Temática de Toxicología de Plaguicidas agradece la participación de sus miembros, del comité editorial de la Revista Internacional de Contaminación Ambiental y del apoyo brindado por el CONACyT para hacer posible esta publicación
BIOESTIMULACIÓN Y BIORREMEDIACIÓN DE RECORTES DE PERFORACIÓN CONTAMINADOS CON HIDROCARBUROS
Get PDFThe drilling of wells for extracting natural gas generates large quantities of drill cuttings contaminated with hydrocarbons. The use of bioremediation methods can reduce the concentration of hydrocarbons in these materials to an acceptable level. Three soils from the central and north zones of the state of Tamaulipas, Mexico, were assayed by mixing them with drill cuttings contaminated with hydrocarbons to find out the ability of soil to perform the bioremediation of hydrocarbons impregnated in the drill cuttings. The biostimulation of soil microorganisms with N and P on the decomposition of hydrocarbons in these mixtures was evaluated. Mixtures of soil and drill cuttings contaminated with hydrocarbons from natural gas extraction wells were poured and incubated in bioremediation cells of 1.0 × 1.2 × 0.4 m for one year. The rate of soil:drill cuttings in these mixtures was 1:1.5. Two agricultural soils and one soil of natural vegetation were studied. Based on the organic carbon content in the mixtures, N and P (urea and monoammonium phosphate) were added, in sufficient amounts to induce a ratio C:N:P of 100:10:1 in the mixture. The hydrocarbons concentration decreased significantly when the drill cuttings, mixed with soil, were incubated in the cells with addition of N and P, reaching 3000 mg/kg of total hydrocarbons, which is the maximum limit allowed in the agricultural soils by the official Mexican standard NOM-138-SEMARNAT/SSA1-2012. Plants of corn (Zea mays) were developed in bioremediated cuttings. The studied soils induced decomposition of hydrocarbons impregnated in drill cuttings and therefore allowed for the bioremediation of cuttings. Biostimulation of soil microorganisms with nutrients N and P, humidity and aeration increased the decomposition of hydrocarbons and fostered the bioremediation of drill cuttings.La excavación de pozos para la extracción de gas natural genera grandes cantidades de recortes de perforación contaminados con hidrocarburos. El uso de métodos de biorremediación puede reducir la concentración de hidrocarburos en estos materiales hasta niveles aceptables. Se ensayaron tres suelos del estado de Tamaulipas, México, en mezcla con los recortes contaminados, para conocer su capacidad de inducir la descomposición de hidrocarburos impregnados en los recortes de perforación y lograr la biorremediación de estos últimos. Se evaluó también la bioestimulación de los microorganismos del suelo con N y P en la descomposición de los hidrocarburos en dichas mezclas. Las mezclas de suelo y recortes de perforación contaminados con hidrocarburos, procedentes de pozos de extracción de gas natural, se vertieron e incubaron por más de un año en celdas de biorremediación de 1.0 × 1.2 × 0.4 m. La proporción suelo:recorte en las mezclas fue de 1:1.5. Se estudiaron dos suelos de uso agrícola y uno de vegetación natural. Con base en el contenido de carbono orgánico de las mezclas, se adicionaron N y P (urea y fosfato monoamónico) en cantidades suficientes para inducir en ellas una proporción C:N:P de 100:10:1. El contenido de hidrocarburos disminuyó significativamente cuando los recortes mezclados con suelo se incubaron dentro de las celdas con la adición de N y P, llegando la concentración hasta alrededor de 3000 mg/kgde hidrocarburos totales, que es el límite máximo permitido en suelos agrícolas por la Norma Oficial Mexicana (NOM-138-SEMARNAT/SSA1-2012). Plantas de maíz (Zea mays) se desarrollaron en los recortes biorremediados. Los suelos estudiados indujeron la descomposición de los hidrocarburos impregnados en los recortes de perforación y por lo tanto provocaron la biorremediación de los recortes. La bioestimulación de los microorganismos del suelo con nutrientes N y P, humedad y aireación aumentó la descomposición de los hidrocarburos y propició la biorremediación de los recortes de perforación
COMPARACIÓN ENTRE DOS MÉTODOS DE VENTILACIÓN EN LA COMPOSICIÓN QUÍMICA DE COMPOST DE ESTIÉRCOLES PECUARIOS
Get PDFIn this work we compared the effects of two ventilation methods on the chemical composition of four livestock manure compost. We conducted four manure composting experiments (Exp) with two ventilation methods: manually with a shovel (Vm), and with perforated polyvinyl chloride (Vt). Exp 1 was designated cattle manure compost (CBo + Vm, CBo + Vt); Exp 2, goat manure compost (CCa + Vm, CCa + Vt); Exp 3, horse manure compost (CEq + Vm, CEq + Vt), and Exp 4, sheep manure compost (COv + Vm, COv + Vt). A completely randomized design was used in each experiment, with three repetitions. A one-way analysis of variance was conducted using the Minitab program and Tukey’s test (p < 0.05) to compare methods. We analyzed temperature, hydrogen potential (pH), electric conductivity (EC), organic matter (OM), organic carbon (C), total nitrogen (N), carbon/nitrogen ratio (C/N), phosphate (PO4), potassium (K), magnesium (Mg), sulfate (SO4), calcium (Ca), sodium (Na), iron (Fe), manganese (Mn), boron (B), zinc (Zn) and copper (Cu). There were highly significant differences in the temperatures observed with the different treatments in the experiments (p = 0.000). No statistical differences were observed in the chemical composition in CBo, CCa and COv based on the ventilation method used (p > 0.05). Statistical differences in C/N were found in CEq + Vt (p = 0.049). The ventilation methods did not impact the chemical characteristics of the cattle, goat and sheep manure composts, but in CEq it was found that placing plastic tubes in the compost piles facilitated greater degradation of the OM and reduced the C/N. Both ventilation methods are recommended in CBo, CCa and COv. And the ventilation method with tubes is recommended in CEq.Este trabajo comparó el efecto de dos métodos de ventilación en la composición química de cuatro compost de estiércoles pecuarios. Para cada tipo de estiércol mezclado se realizó un experimento de compostaje. En cada experimento (Exp) se ensayaron dos métodos de ventilación: manual con pala (Vm) y con tubos de policloruro de vinilo perforados (Vt). El Exp 1 se denominó compost estiércol bovino (CBo + Vm, CBo + Vt), el Exp 2 compost estiércol caprino (CCa + Vm, CCa + Vt), el Exp 3 compost estiércol equino (CEq + Vm, CEq + Vt) y el Exp 4 compost estiércol ovino (COv + Vm, COv + Vt). Durante el proceso se analizaron temperatura, potencial de hidrogeno (pH), conductividad eléctrica (CE), materia orgánica (MO), carbono orgánico (C), nitrógeno total (N), relación carbono/nitrógeno (C/N), fosfato (PO4), potasio (K), magnesio (Mg), sulfato (SO4), calcio (Ca), sodio (Na), hierro (Fe), manganeso (Mn), boro (B), zinc (Zn) y cobre (Cu). Para cada experimento se utilizó un diseño completamente aleatorizado con tres repeticiones. En las variables de composición química se realizó un análisis de varianza de un factor utilizando el programa Minitab y las medias se compararon con la prueba de Tukey (p < 0.05). La temperatura en cada experimento mostró diferencias significativas entre tratamientos (p = 0.000). Los productos provenientes de CBo, CCa y COv no presentaron diferencias en la composición química por el método de ventilación (p > 0.05). El producto proveniente de CEq + Vt presentó menor relación C/N (p = 0.049). Los métodos de ventilación no influyeron en las características químicas de los compost de estiércol bovino, caprino y ovino, sin embargo, en el compost de estiércol equino al colocar tubos en las pilas de compostaje, se favoreció la degradación de la MO y redujo la relación C/N. Se concluye que los dos métodos de ventilación se recomiendan en los CBo, CCa y COv. Y el método de ventilación con tubos se recomienda en el CEq
RESPIRACIÓN POTENCIAL DURANTE LA BIOESTIMULACIÓN DE UN SUELO CONTAMINADO CON HIDROCARBUROS AROMATICOS POLICÍCLICOS
Get PDFPolycyclic aromatic hydrocarbons (PAHs) are organic compounds that may persist in the environment due to their hydrophobicity and insolubility in water, posing the risk of entering the food chain. Some soil microorganisms are potentially capable of degrading PAHs. The addition of nutrients may accelerate the rate of biodegradation if soil conditions are favorable. The objectives were to study the degradation capacity of native soil microorganisms to degrade selected PAHs in an artificially contaminated soil, and to evaluate the effect of nutrient availability. The influence of the chemical structure of the contaminant was also studied. An incubation assay was performed, using a typic hapludoll soil artificially contaminated with anthracene or phenanthrene. Microbial activity was indirectly estimated through the production of CO2. Soil contamination with anthracene or phenanthrene did not affect the initial soil microbial activity. The total emission of CO2 increased in contaminated soils compared to the pristine ones, due to the degradation of contaminants. At 60 days, soil samples were analyzed by gas chromatography-mass spectrometry-mass. The removal of anthracene and phenanthrene from the soil was different, and it was related to bioavailability. Anthracene and phenanthrene concentration decreased 75 - 77 % or 89 - 91 %, respectively, indicating the ability of native soil microorganisms to rapidly degrade both pollutants. No significant differences were observed between treatments with and without nutrients, concluding that nutrient availability was not a limiting factor for the catabolic activity of soil microorganismsLos hidrocarburos aromáticos policíclicos (HAP) son compuestos orgánicos que pueden persistir en el ambiente debido a su hidrofobicidad y a su baja solubilidad en agua, lo que representa un riesgo de ingresar a la cadena trófica. Ciertos microorganismos edáficos son potencialmente capaces de degradarlos. La incorporación de nutrientes puede acelerar la tasa de biodegradación si las condiciones del suelo son favorables. Los objetivos del presente trabajo fueron estudiar el efecto disipador de los microorganismos edáficos nativos en un suelo contaminado artificialmente con dos HAP (antraceno o fenantreno), además de evaluar el efecto en la disponibilidad de macro y micro nutrientes. Adicionalmente, se estudió la influencia de la estructura química del contaminante en el proceso de biorremediación. Se realizó un ensayo de incubación con un suelo hapludol típico contaminado artificialmente con antraceno o con fenantreno. La actividad microbiana se estimó en forma indirecta través de la producción de CO2. La presencia de antraceno o de fenantreno no afectó la actividad microbiana edáfica inicial. Se observó un incremento en la emisión total de CO2 en los suelos contaminados comparado con los suelos sin contaminar debido a la degradación de los contaminantes. Al término de 60 días se analizaron los suelos por cromatógrafía gaseosa con detector de espectrometría de masas (CG-MS) -masa. Según los tratamientos, la concentración de antraceno y de fenantreno disminuyó un 75 - 77 % o un 89 - 91 %, respectivamente. Lo que indica la capacidad de los microorganismos nativos edáficos para degradar rápidamente ambos contaminantes. La disipación del fenantreno fue mayor que la correspondiente al antraceno, lo que fue atribuido a su diferente biodisponibilidad en el suelo. No se observaron diferencias significativas entre tratamientos con y sin nutrientes, por lo que se concluye que la disponibilidad de éstos no fue limitante para la actividad catabólica de los microorganismos edáficos.