Revista Internacional de Contaminación Ambiental
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METALES PESADOS Y BIOMARCADORES DE ESTRÉS OXIDATIVO EN LA ALMEJA Tivela mactroides (Born, 1778)
Get PDFTo evaluate the levels of heavy metals (Cd, Pb, Cu y Zn) in edible tissue, as well as some molecular biomarkers of oxidative stress, in the digestive gland of the triagonal clam Tivela mactroides from Caicara beach (Venezuela) during different pluviometric seasons, we proceeded to collect between 90 and 100 organisms during August and December 2007 (moderate rain and rain-drought transition, respectively), and April and July 2008 (drought and intense rain, respectively). Heavy metal levels were measured by inductively coupled optical emission spectrometry, while the concentrations of metallothioneins (MTs), total thiols (-SHT), free thiols (-SHF), total proteins (PT), and thiobarbituric acid reactive substances (TBARS) were determined by colorimetric methods. Cd, Pb and Cu concentrations increased in rainfall periods and Zn in the rain-drought transition. Cd and Pb concentrations in T. mactroides were elevated in comparison with clams collected from other Venezuelan coastal areas, exceeding the values suggested by international organizations, especially during the maximal rainfall period. MT, -SHF and TBARS concentrations did not show significant variations between collection periods; however, -SHT decreased in the period of maximum precipitation. The results of oxidative stress biomarkers did not indicate molecular alterations by contamination; however, accumulated levels of Cd and Pb are a signal of alarm of bioavailability and entrance of xenobiotics of anthropogenic origin.Con el objetivo de cuantificar los niveles de metales pesados (Cd, Pb, Cu y Zn) en el tejido blando de la almeja Tivela mactroides de playa Caicara (Venezuela), así como algunos biomarcadores moleculares de estrés oxidativo en la glándula digestiva de este organismo durante distintas temporadas pluviométricas, se procedió a recolectar de 90 a 100 ejemplares durante agosto y diciembre de 2007 (lluvias moderadas y transición lluvia-sequía, respectivamente), así como en abril y julio de 2008 (sequía y lluvias intensas, respectivamente). Las medidas de metales pesados se realizaron por espectrometría de emisión óptica con plasma acoplado inductivamente, y los contenidos de metalotioneínas (MT), tioles totales (-SHT), tioles libres (-SHL), proteínas totales (PT) y substancias reactivas al ácido tiobarbitúrico (TBARS) se determinaron por métodos colorimétricos. Las concentraciones de Cd, Pb y Cu se incrementaron en los periodos de lluvias y las de Zn en la transición lluvia-sequía. Los niveles de Cd y Pb en T. mactroides fueron altos en comparación con almejas provenientes de otras zonas costeras de Venezuela, excediendo los valores establecidos por organizaciones internacionales, especialmente durante el periodo de máxima pluviosidad. Los niveles de MT, -SHL y TBARS no mostraron variaciones significativas entre épocas de recolección; sin embargo, los niveles de -SHT disminuyeron en el máximo periodo lluvioso. Los resultados de los biomarcadores de estrés oxidativo no mostraron indicios de alteraciones moleculares relacionadas con contaminación; sin embargo, los niveles acumulados de Cd y Pb señalan una alarma de disponibilidad e ingreso de xenobióticos de origen antrópico
INVENTARIO DE CARBONO EN LA RECUPERACIÓN DE PLAYAS CUBANAS
Get PDFThe objective of this study is to construct an inventory of carbon for the nourishment of Cuban sand beaches. It uses data of a beach nourishment project executed in 2016 in the archipelago of Jardines del Rey in Ciego de Ávila, Cuba, according to an algorithm of carbon inventory for the recovery of beaches. The carbon budget was 62531.04 Mg, of which 952.36 were contained in consumed fossil fuels, 2338.95 were retained in the protected or rehabilitated vegetation, and 59239.73 Mg were retained in carbonate sands. The mole ratio in carbon compounds was used to transform the inventory into a net capture of 5084.16 Mg of carbon dioxide and the net depositions of calcium carbonate at 493652.11 Mg. These amounts were valued at 127 104.06 and 30 413 906.67 Cuban pesos, respectively. The total amounts were compared with the cost of investment. A positive net present value was deducted, representing a profitable investment in terms of carbon capture and increased carbonate sand surfaces on the studied beaches. We recommend to continue the study of sand beaches, in other to complete the inventory by our further research on carbon emission due to changes produced in the vegetation of the submarine zone.El objetivo de esta investigación fue hacer un inventario de carbono para la recuperación de playas arenosas cubanas. Se emplearon los datos de la inversión ejecutada en el archipiélago de Jardines del Rey en Ciego de Ávila, Cuba, en 2016, y un algoritmo del inventario de carbono para la recuperación de playas. El presupuesto de carbono fue de 62531.04 Mg, de los cuales 952.36 estuvieron contenidos en los combustibles consumidos, 2338.95 fueron retenidos por la vegetación protegida o sembrada y 59239.73 por las arenas vertidas. La proporción de moles en los compuestos de carbono se empleó para transformar el inventario en una captura de 5084.16 Mg de dióxido de carbono de la atmósfera y una deposición neta de 493652.11 Mg de carbonato de calcio en las playas. Las cuantías se valoraron en 127 104.06 y 30 413 906.67 pesos cubanos (MT), respectivamente. Los valores se sumaron y el total se comparó con el costo de la inversión. Se dedujo un valor actual neto positivo representativo de una inversión rentable en términos de captura de carbono y de incremento de superficies con arenas carbonatadas en las playas estudiadas. Recomendamos continuar el estudio de las playas arenosas para completar el inventario con la futura investigación de la emisión de carbono derivada de los cambios producidos en la vegetación de la zona submarina
INCREMENTO DE NITRÓGENO EN Thalassia testudinum POR EL APORTE DE NITRÓGENO DISUELTO INORGÁNICO DE AGUAS RESIDUALES DURANTE PRECIPITACIONES EXTRAORDINARIAS
Get PDFThe Mexican Caribbean reef lagoons are oligotrophic ecosystems, where residual water discharges (RWD) associated with tourist activity to groundwater aquifer systems supply additional dissolved inorganic nitrogen (DIN) to these lagoons. The contribution of DIN can be exacerbated in years with extraordinary precipitation (> 2500 mm in 2013) in the Mexican Caribbean. Thalassia testudinum seagrass is characterized by a nitrogen content < 2 % dry weight. If the DIN flow increases in exceptional rainfall, it is expected that the content of nitrogen in T. testudinum will increase with respect to the historical average precipitation (1200 mm) of the last 30 years. In the present work the nitrogen content in T. testudinum is quantified in order to determine changes associated with the RWD during the dry and rainy season from 2010 to 2016 in Akumal Bay. The nitrogen content in the leaves of T. testudinum was quantified in an elemental analyzer. In the years of 2010, 2012, 2015 and 2016 the nitrogen content in T. testudinum was similar between dry and rainy season. In the years of 2013 and 2014, the nitrogen content was higher in the rainy season with respect to the dry season. This evidence suggests that in periods of extraordinary rainfall, the flow of DIN to the coastal lagoons of the Caribbean increases, making this nitrogen available to the seagrass T. testudinum.Las lagunas de arrecife del Caribe mexicano son ecosistemas oligotróficos, donde las descargas de agua residuales (DAR) asociadas a la actividad turística, en algunos casos son vertidas a los acuíferos subterráneos, suministrando nitrógeno inorgánico disuelto (NID) a las mismas. El aporte de NID puede ser exacerbado en años con precipitación extraordinaria (2013 con > 2500 mm) en el Caribe mexicano. Por su parte, el pasto marino Thalassia testudinum se caracteriza por un contenido de nitrógeno < 2 % en peso seco. Si el flujo de NID se incrementa debido a precipitaciones excepcionales, es de esperar que el contenido de nitrógeno en T. testudinum aumente con respecto a la precipitación promedio histórica (1200 mm) de los últimos 30 años. En el presente trabajo se cuantificó el contenido de nitrógeno en T. testudinum mediante un analizador elemental, para determinar cambios asociados con las DAR durante la época seca y lluviosa entre los años 2010 a 2016 en la Bahía de Akumal. En los años de 2010, 2012, 2015 y 2016 el contenido de nitrógeno fue similar entre épocas y en los años 2013 y 2014 fue mayor en la época de lluvias con respecto a la época seca. Esto sugiere que, en periodos de precipitaciones extraordinarias el flujo de NID a las lagunas costeras del Caribe incrementa haciendo disponible este nitrógeno para T. testudinum
USO DE UN INÓCULO ENDÓGENO PARA ACELERAR LA DEGRADACIÓN DE MATERIA ORGÁNICA EN UNA GRANJA PORCINA POR MEDIO DEL PROCESO DE COMPOSTAJE
Get PDFIn Mexico, pork farms generate organic residues which often are not appropriately treated before being discharged to waste waters or are treated by methods that directly or indirectly damage the environment. Thus, the objective of this study was to evaluate the effect of a bacterial inoculum on the degradation of organic residues under composting conditions. Solid residues from the effluent sump in a pig farm were mixed with sawdust to form a degradation matrix, where pig carcasses were composted. This artificial ecosystem was used to promote the growth and eventual isolation of various microbial species, which were then used to produce a bacterial endogenous inoculum that was maintained in a minimum basal medium based on compost extract in a mineral solution. The inoculum was added to three 150-kg degradation matrices. Three reference matrices, prepared from pig carcasses as described above, were added with 0.1 % peptone solution only. After 98 days of composting, microbiological and bromatological analysis, as well as a bioassay, showed that the inoculum accelerated the decomposition of pig carcasses. Furthermore, the time required to decrease the pathogenic microbial load was reduced in inoculated matrices and the germination index of Raphanus sativus seeds improved, while nitrogen content increased continuously.Las unidades de producción porcinas en México generan residuos orgánicos que hasta el momento no se han tratado adecuadamente, o bien los métodos existentes afectan el ambiente de manera directa o indirecta. El objetivo del estudio fue evaluar el efecto del uso de un inóculo bacteriano sobre la descomposición de ciertos residuos orgánicos sometidos al proceso de compostaje. Se emplearon residuos sólidos extraídos de la fosa recolectora de aguas residuales de una granja porcina y se mezclaron con aserrín para formar una matriz de degradación donde se colocaron cadáveres de cerdo. Este ecosistema fomentó el desarrollo y posterior aislamiento de especies microbianas que se usaron para elaborar un inóculo endógeno bacteriano mantenido en un medio mínimo basal, constituido por extracto de compost en una solución mineral. El inóculo endógeno elaborado se adicionó a tres matrices de 150 kg cada una, y se construyeron otras tres matrices de referencia —todas las cuales contenían cadáveres de cerdo— que sólo recibieron agua peptonada al 0.1 %. Después de un periodo de compostaje de 98 días y tras un análisis bromatológico, microbiológico y un bioensayo, se observó que el inóculo aceleró la descomposición de los cadáveres de cerdo. También se redujo el tiempo necesario para disminuir la carga microbiana patógena. Adicionalmente, el índice de germinación de las semillas de rábano mejoró en las matrices inoculadas, mientras que el contenido de nitrógeno aumentó con el tiempo
METHOD FOR QUANTIFYING AND CHARACTERIZATION OF MICROPLASTICS IN SAND BEACHES
Get PDFIn recent years microplastics have become an issue of global concern due to the negative effects that they cause in the environment, such as their ingestion by marine species and their capacity to adsorb pollutants from water. To face this problem research has been performed around the world to study the presence of microplastics in marine environments. However, the use of different on-field sampling and laboratory characterization techniques, sometimes difficult to replicate, hinders the possibility to compare results. This paper proposes a methodology for sampling and characterization of microplastics on the 1 – 5 mm range present on sand beaches. First, a comparison is made between the different techniques used for sampling, extraction, classification and identification of microplastics on studies performed on the last five years. Then the proposed methodology, which involves sampling in the high tide zone, at 5 cm depth, is explained in detail. The method has a low cost, as it uses simple equipment available in most of the labs. It can be easily replicable and allows presenting results in different units. The decision criteria, materials and steps in each of its seven stages (identification of sampling zone, selection of sampling points, sampling, drying, extraction, quantification and classification of microplastics) are described. Also, it explains a process to eliminate false positives caused by organic matter or shells. This work aims to improve the efficiency, replicability and homogeneity in the study of microplastics.In recent years microplastics have become an issue of global concern due to the negative effects that they cause in the environment, such as their ingestion by marine species and their capacity to adsorb pollutants from water. To face this problem research has been performed around the world to study the presence of microplastics in marine environments. However, the use of different on-field sampling and laboratory characterization techniques, sometimes difficult to replicate, hinders the possibility to compare results. This paper proposes a methodology for sampling and characterization of microplastics on the 1 – 5 mm range present on sand beaches. First, a comparison is made between the different techniques used for sampling, extraction, classification and identification of microplastics on studies performed on the last five years. Then the proposed methodology, which involves sampling in the high tide zone, at 5 cm depth, is explained in detail. The method has a low cost, as it uses simple equipment available in most of the labs. It can be easily replicable and allows presenting results in different units. The decision criteria, materials and steps in each of its seven stages (identification of sampling zone, selection of sampling points, sampling, drying, extraction, quantification and classification of microplastics) are described. Also, it explains a process to eliminate false positives caused by organic matter or shells. This work aims to improve the efficiency, replicability and homogeneity in the study of microplastics
PRODUCTION OF LOW-COST BIOCOMPOSITE MADE OF PALM FIBERS WASTE AND GYPSUM PLASTER
Get PDFIn recent years, natural fibers have been increasingly employed in building materials, due to their proprieties for manufacturing low-cost, renewable, and eco-friendly composites. This study aimed to develop a biocomposite based on local materials: natural fibers and plaster. The natural fibers used are date palm fibers waste from Gabes oasis, Tunisia. In order to characterize these materials, many properties were investigated experimentally (i.e., size, thermal behavior, and microstructural characteristics). On the biocomposite samples, compressive and flexural strength, as well as water absorption tests were performed, properties which increased with the addition of fiber wastes. In order to improve the composite durability, chemical treatments with sodium hypochlorite and resin coating were carried out to decrease surface tension and improve adhesion with the plaster matrix. As a result, the biocomposite showed satisfactory physical, thermal, and mechanical performances, which qualify it as a thermal insulation building material.In recent years, natural fibers have been increasingly employed in building materials, due to their proprieties for manufacturing low-cost, renewable, and eco-friendly composites. This study aimed to develop a biocomposite based on local materials: natural fibers and plaster. The natural fibers used are date palm fibers waste from Gabes oasis, Tunisia. In order to characterize these materials, many properties were investigated experimentally (i.e., size, thermal behavior, and microstructural characteristics). On the biocomposite samples, compressive and flexural strength, as well as water absorption tests were performed, properties which increased with the addition of fiber wastes. In order to improve the composite durability, chemical treatments with sodium hypochlorite and resin coating were carried out to decrease surface tension and improve adhesion with the plaster matrix. As a result, the biocomposite showed satisfactory physical, thermal, and mechanical performances, which qualify it as a thermal insulation building material
TRACE METALS IN TWO WILD POPULATIONS OF THE SQUALID CALLISTA CLAM (Megapitaria squalida) IN THE SOUTHEASTERN GULF OF CALIFORNIA, MEXICO
Get PDFThe squalid callista clam (Megapitaria squalida) is a popular raw seafood item for human consumption; however, as a filter feeder, this clam accumulates heavy metals from natural and anthropogenic sources. The concentrations of copper (Cu), cadmium (Cd), chromium (Cr), nickel (Ni), lead (Pb), zinc (Zn), arsenic (As), and mercury (Hg) in sediments and the soft tissues of M. squalida from two sites on the southeastern coast of the Gulf of California, Mexico, were evaluated from April 2016 to April 2017 on a monthly basis. The metal concentrations in sediments from both sites did not exceed the Mexican and international regulations. Concentrations of Cd and Pb in the clams from Altata bay (2.49 and 5.68 µg/g dw, respectively) and Agiabampo bay (2.38 and 5.54 µg/g dw, respectively) exceeded the permissible limits recommended by Mexican sanitary regulations, thus representing a threat to human health. The higher values of Cd, As, and Hg obtained for the biota sediment accumulation factor in both sampling areas indicate that squalid callista is a strong accumulator of these metals. The metal burdens in sediments and M. squalida soft tissues are influenced by chemicals from agriculture and aquaculture, as well as urban sewage disposal near both sites. This study brings useful information on metal bioaccumulation in one of the most important commercial clam species on the Pacific coast.The squalid callista clam (Megapitaria squalida) is a popular raw seafood item for human consumption; however, as a filter feeder, this clam accumulates heavy metals from natural and anthropogenic sources. The concentrations of copper (Cu), cadmium (Cd), chromium (Cr), nickel (Ni), lead (Pb), zinc (Zn), arsenic (As), and mercury (Hg) in sediments and the soft tissues of M. squalida from two sites on the southeastern coast of the Gulf of California, Mexico, were evaluated from April 2016 to April 2017 on a monthly basis. The metal concentrations in sediments from both sites did not exceed the Mexican and international regulations. Concentrations of Cd and Pb in the clams from Altata bay (2.49 and 5.68 µg/g dw, respectively) and Agiabampo bay (2.38 and 5.54 µg/g dw, respectively) exceeded the permissible limits recommended by Mexican sanitary regulations, thus representing a threat to human health. The higher values of Cd, As, and Hg obtained for the biota sediment accumulation factor in both sampling areas indicate that squalid callista is a strong accumulator of these metals. The metal burdens in sediments and M. squalida soft tissues are influenced by chemicals from agriculture and aquaculture, as well as urban sewage disposal near both sites. This study brings useful information on metal bioaccumulation in one of the most important commercial clam species on the Pacific coast
THE MEXICAN AXOLOTL´S (Ambystoma mexicanum) EARLY DEVELOPMENT AND SURVIVAL IS AFFECTED BY COMMERCIAL GRADE MALATHION AND DICHLORVOS ORGANOPHOSPHORUS PESTICIDES
Get PDFThe wild population of the Mexican axolotl (Ambystoma mexicanum) is subject to a dramatic decline as a consequence of deteriorating conditions in its natural habitat, Xochimilco. The common use of organophosphorus pesticides (OPPs) in the region affects water quality and is partially responsible for the axolotl decline. This could be a consequence of the delicate nature of axolotls, which are struggling to survive under contaminated conditions at early stages of development. In this regard, we aimed to extend the knowledge of OPPs effect on the survival of axolotls in their early stage of development, within the context of detrimental environment conditions using commercial grade OPPs. Fertilized axolotl eggs were treated with malathion (MLT), dichlorvos (DDVP), and a depurated group in which the OPPs exposure was stopped earlier, as well as an untreated control group. Changes in hatching, survival, size, and morphology were monitored and analyzed in embryos and early larvae. Our results showed that MLT and DVPP accelerate egg hatching and mortality even after the early removal of OPPs from the medium. OPPs also caused a reduced size and morphological abnormalities. It is proposed that such abnormalities would jeopardize the survival of the wildlife axolotl. Our results suggest that OPPs can cause irreversible damage to the axolotl embryos, stopping their normal development, causing death and reducing their chances of survival in their natural environment.The wild population of the Mexican axolotl (Ambystoma mexicanum) is subject to a dramatic decline as a consequence of deteriorating conditions in its natural habitat, Xochimilco. The common use of organophosphorus pesticides (OPPs) in the region affects water quality and is partially responsible for the axolotl decline. This could be a consequence of the delicate nature of axolotls, which are struggling to survive under contaminated conditions at early stages of development. In this regard, we aimed to extend the knowledge of OPPs effect on the survival of axolotls in their early stage of development, within the context of detrimental environment conditions using commercial grade OPPs. Fertilized axolotl eggs were treated with malathion (MLT), dichlorvos (DDVP), and a depurated group in which the OPPs exposure was stopped earlier, as well as an untreated control group. Changes in hatching, survival, size, and morphology were monitored and analyzed in embryos and early larvae. Our results showed that MLT and DVPP accelerate egg hatching and mortality even after the early removal of OPPs from the medium. OPPs also caused a reduced size and morphological abnormalities. It is proposed that such abnormalities would jeopardize the survival of the wildlife axolotl. Our results suggest that OPPs can cause irreversible damage to the axolotl embryos, stopping their normal development, causing death and reducing their chances of survival in their natural environment
HEAVY METALS BIOABSORPTION AND SOIL STABILIZATION BY Sarcocornia neei FROM EXPERIMENTAL SOILS CONTAINING MINE TAILINGS
Get PDFIn the Atacama region of northern Chile, there are a large number of abandoned mines and dams with tailings and little flora development. Sarcocornia neei, a halophytic plant growing in Chilean coastal areas, is highly tolerant to contaminated soils associated with mine tailings. The potential for bioabsorption of heavy metals and arsenic and the substrate stabilization by this species was evaluated in soil experimentally contaminated with mine tailings from the Copiapó Valley. Sarcocornia neei grew well, although more slowly, in experimental soils containing mainly Fe, Cu and Mn. In an advanced vegetative development stage, S. neei roots were able to stabilize the contaminated experimental soils, agglomerating them in more than 80 % and extracting chemical elements from them. These characteristics are potentially useful for phytoremediation and reduction of contamination by fine-size particles from mine tailings and contaminated soils.In the Atacama region of northern Chile, there are a large number of abandoned mines and dams with tailings and little flora development. Sarcocornia neei, a halophytic plant growing in Chilean coastal areas, is highly tolerant to contaminated soils associated with mine tailings. The potential for bioabsorption of heavy metals and arsenic and the substrate stabilization by this species was evaluated in soil experimentally contaminated with mine tailings from the Copiapó Valley. Sarcocornia neei grew well, although more slowly, in experimental soils containing mainly Fe, Cu and Mn. In an advanced vegetative development stage, S. neei roots were able to stabilize the contaminated experimental soils, agglomerating them in more than 80 % and extracting chemical elements from them. These characteristics are potentially useful for phytoremediation and reduction of contamination by fine-size particles from mine tailings and contaminated soils