Revista Internacional de Contaminación Ambiental
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ANALISIS DE LA BIORREMOCIÓN DE HIDROCARBUROS AROMÁTICOS POLICÍCLICOS EN AGUA POR SPME-GC/MS
Get PDFThe persistent organic pollutants in water, such as, polycyclic aromatic hydrocarbons (PAHs) represent a potential risk for the environment and human health. The USEPA classified the PAHs pyrene, phenanthrene and naphthalene within the 16 PAH of the priority pollutants for their toxicity, distribution and occurrence in the environment. The aim of this study was to evaluate a microbial consortium from an ore waste as an alternative to remove these three PAHs in water. The consortium was stabilized using the PAHs as the only carbon source. The bioremoval of the PAHs was analyzed using the environmentally friendly technique called solid phase microextraction coupled with gas chromatography and mass spectrometry (SPME-GC/MS). The PAHs percent recoveries were reported in a range of 85 - 97 %. The percentage removal for naphthalene, pyrene and phenanthrene was 99 %, 98 % and 94 %, respectively at a concentration of 100 mg/L after 14 days of incubation. The pH values reported (pH = 5.2 - 5.6) may indicate the PAHs degradation in water. It is concluded that the microbial consortium studied has potential for removal of PAHs from water.Los contaminantes orgánicos persistentes en el agua como los hidrocarburos aromáticos policíclicos (HAP), representan un riesgo potencial para el ambiente y la salud. La Agencia de Protección Ambiental de los Estados Unidos de Norteamérica (USEPA) clasifica a los HAP pireno, fenantreno y naftaleno dentro de los 16 HAP prioritarios para la USEPA por sus efectos tóxicos, distribución y presencia en el ambiente. El objetivo de este estudio fue evaluar un consorcio microbiano de un desecho de mineral (jales mineros) como una alternativa de eliminación de estos tres HAP en agua. El consorcio se estabilizó utilizando los HAP como única fuente de carbono. La biorremoción se analizó utilizando la técnica ambientalmente amigable de microextracción en fase sólida acoplada a cromatografía de gases y espectrometría de masas (SPME-GC/MS). El porcentaje de recuperación de los HAP se reportó en un rango del 85 al 97 %. El porcentaje de eliminación de naftaleno, pireno y fenantreno fue de 99 %, 98 % y 94 %, respectivamente, a 100 mg /L después de 14 días de incubación. Los valores de pH reportados (pH = 5.2 - 5.6) pueden indicar la degradación de los HAP en agua. Se concluye que el consorcio microbiano estudiado tiene potencial para la remoción de HAP en agua
EFECTO DEL COBRE PARA LA REMOCIÓN DE SULFATO EN UN REACTOR DE LECHO FIJO
Get PDFMining of sulfide-rich pyritic ores produce acid mine drainage (AMD), which contains high metal concentrations and have acid pH, causing major environmental problems. Over the last 20 years a variety of passive AMD treatment systems, like anaerobic wetlands, bioreactors and permeable reactive barriers, have been studied. Under controlled conditions bioreactors employ inoculants of sulfate-reducing bacteria (SRB) to treat effluents and capture commercial grade metals. The objective of this research was to evaluate the effect of Cu on the removal efficiency of sulfate in a fixed bed reactor. During 28 d the fixed bed reactor maintained a hydraulic residence time (HRT) of 12 h and an influent rate of 0.67 gCOD/gSO42–. Phase I (synthetic solution with 50 mg Cu/L) lasted 7 d, allowing Cu removal of 99.59 ± 0.43 % and sulfide production of 39.29 mg S2-/L∙d. Sulfate-reducing activity (SRA) was not affected (40.25 mg S2-/L∙d) during Phase II (21 d without Cu). Results showed no significant alteration in sulfate and COD removal, as well as sulfur production after the addition of Cu. It is concluded that SRB can be used for AMD treatment.La explotación de minerales ricos en pirita genera un drenaje ácido (DAM), el cual presenta un pH ácido, alta concentración de metales y sulfatos, y pueden causar problemas ambientales. En los últimos 20 años se han estudiado sistemas pasivos para el tratamiento de DAM, como las lagunas anaerobias, biorreactores y las barreras permeables. Los biorreactores, en condiciones controladas, emplean inóculos de bacterias sulfato reductoras (BSR) para tratar efluentes y precipitar metales de grado comercial. El objetivo de este trabajo fue analizar el efecto del cobre (Cu) en la remoción de sulfato en un reactor de lecho fijo. Durante 28 d se operó un reactor de lecho fijo, con un tiempo de residencia hidráulico (TRH) de 12 h y 0.67 g DQO/g SO42–. Durante 7 d la Fase I (solución sintética con 50 mg Cu/L) permitió una remoción de Cu del 99.59 ± 0.43 % y una producción de sulfuro de 39.29 mg S2–/L∙d. Posteriormente, el reactor operó sin Cu (Fase II), para demostrar que no se afectó la actividad sulfato reductora (ASR) (40.25 mg S2–/L∙d). Los resultados no muestran alteraciones significativas en la remoción de materia orgánica y sulfato, así como en la producción de sulfuro después de la adición de Cu. Se concluye que se pueden utilizar las BSR para el tratamiento de DAM
FOTOCATÁLISIS HETEROGÉNEA PARA LA REMOCIÓN DE ANTIMONIO (Sb) EN AGUA UTILIZANDO DIÓXIDO DE TITANIO (TiO2) COMO CATALIZADOR
Get PDFThe objective of this investigation was to manipulate the heterogeneous photocatalysis method for the removal of antimony (Sb) in industrial waters. Titanium dioxide (TiO2) was used as a catalyst and hydrogen peroxide as the oxidant agent. The system consisted of a storage tank and a flat tubular solar collector which was exposed to the radiation in continuous flow for several exposure times, modifying the concentration of the catalyst, oxidizing agent and the pH of the solution. The levels of Sb expected in the removal were 0.006 mg / L based on the maximum permissible limits of the United States Environmental Protection Agency (EPA) for drinking water. Experimental tests were made until finding the highest percentages of removal. The results obtained were 74.2% at pH 7 with 1 g of TiO2 and 10 mL per h of H2O2, 99.54% at pH 7, with 4 g of TiO2, 86.72% at pH 4 with 3 g of TiO2, at 10, 20 and 8 h of exposure respectively, with a UV light range of 4 to 11 monitored from the city’s weather station. It is concluded that at neutral pH with an amount of 4 g of TiO2, without adding the H2O2, in a time of 20 h, the developed photocatalytic system removed the Sb of the treated water in acceptable concentrations to the EPA’s drinking water regulations. El objetivo de esta investigación fue manipular el método de fotocatálisis heterogénea para remoción de antimonio (Sb) en aguas industriales. Se utilizó el dióxido de titanio (TiO2) como catalizador y peróxido de hidrógeno (H2O2) como agente oxidante. El sistema fue conformado por un tanque de almacenamiento y un colector solar tubular plano el cual estuvo expuesto a la radiación en flujo continuo por varios tiempos de exposición, modificando la concentración del catalizador, agente oxidante y el pH de la solución. Los niveles de Sb esperados en la remoción fueron de 0.006 mg/L tomando como base los límites máximos permisibles de la Agencia de Protección Ambiental de los Estados Unidos de América (EPA) para agua potable. Se hicieron pruebas experimentales hasta encontrar los porcentajes más elevados de remoción. Los resultados obtenidos fueron de 74.2% a pH 7 con 1 g de TiO2 y 10 mL por h de H2O2, 99.54% a pH 7 con 4 g de TiO2, 86.72% a pH 4, con 3 g del TiO2, a 10, 20 y 8 h de exposición respectivamente, con un rango de luz UV de 4 a 11 monitoreada de la estación meteorológica de la ciudad. Se concluye que a pH neutro con una cantidad de 4 g de TiO2, sin agregar el H2O2,en un tiempo de 20 h, el sistema fotocatalítico desarrollado removió el Sb del agua tratada en concentraciones aceptables a la normatividad de agua potable de la EPA.
TRAZABILIDAD DE ARSÉNICO EN AGUA DE RIEGO AGRÍCOLA EN EL CENTRO SUR DEL ESTADO DE CHIHUAHUA, MÉXICO
Get PDFThe natural presence of arsenic in groundwater is a global problem since it affects human health. The metalloid has been detected in crops irrigated with As-contaminated water, especially in Asia. Therefore, the objective of this research was to determine the total As concentration (As-tot) in agricultural wells at the south-central part of Chihuahua State, as well as its traceability to soil and crops in the territory. 119 wells for agricultural irrigation were sampled. The soil sampling was realized in six sites, in each one 24 samples were collected; in the same sites, 32 onion and 37 chili plants were collected. As-tot concentration was determined by atomic absorption spectrometry with hydride generator. 11 % of the wells exceeded the maximum permissible level (MPL) of As-tot in water for agricultural use (100 μg/L). The highest As-tot concentration was 576 μg/L. In the quadrant with the highest As-tot concentration in soil, 42 % of the samples exceeded the MPL for agricultural soil (22 mg/kg), displaying a maximum concentration of 47.5 mg/kg. The highest As-tot presence on plants was in root, 7.4 mg/kg in chili and 28.8 mg/kg in onion. However, 0.16 mg/kg in chili and 0.38 mg/kg in onion were also identified in fruits. It was demonstrated that, in the study region, the crops irrigation with water high As levels generates the metalloid movement to matrices that are related to the population intake.La presencia natural de arsénico en agua subterránea es un problema global ya que afecta a la salud humana. El metaloide ha sido detectado en cultivos regados con esta agua, sobre todo en Asia. El objetivo de esta investigación fue determinar la concentración de arsénico total (As-tot) en pozos agrícolas al centro-sur del estado de Chihuahua, así como su trazabilidad a suelo y cultivos del territorio. Se muestrearon 119 pozos de riego agrícola. El muestreo de suelo se realizó en seis sitios, en cada uno se colectaron 24 muestras; en estos mismos se colectaron 32 plantas de cebolla y 37 de chile. La concentración de As-tot se determinó en todas las matrices por espectrometría de absorción atómica con generador de hidruros. El 11 % de los pozos superaron el límite máximo permisible (LMP) de As-tot en agua para uso agrícola (100 µg/L); la mayor concentración de As-tot fue 576 µg/L. En el sitio con mayor concentración de As-tot en suelo, el 42 % de las muestras superaron el LMP para uso agrícola (22 mg/kg), presentando una concentración máxima de 47.5 mg/kg. La mayor presencia de As-tot en cultivos fue en raíz, 7.4 mg/kg en chile serrano y 28.8 mg/kg en cebolla. Sin embargo, en fruto se determinó 0.16 mg/kg en chile y 0.38 mg/kg en cebolla. Se demostró que en la región el riego de cultivos con agua con altos niveles de As-tot genera movimiento del metaloide a matrices que se relacionan con la ingesta de la población
BIOCONCENTRACIÓN DE Pb, Cd Y As EN BIOMASA DE Eleocharis macrostachya (CYPERACEAE)
Get PDFThe increasing problems of water pollution have created unhealthy spaces for inhabit. Phytoremediation is a technique that use plants to remediate water, soil and air. Therefore, the ability of Eleocharis macrostachya to remediate contaminated water with lead (Pb), cadmium (Cd) and arsenic (As) was analyzed. The plants were collected, washed and transplanted in sand and placed in pots by treatment groups: T1 (Control), T2 (As 2 mg/L, Cd 10 mg/L, Pb 20 mg/L), T3 (As 4 mg/L, Cd 100 mg/L, Pb 200 mg/L) and T4 (As 8 mg/L, Cd 200 mg/L, Pb 400 mg/L). The pots were irrigated for 210 days, at the end of the experiment soil and plants were separated for digestion and subsequent analysis by inductively coupled plasma - optical emission spectrometry (ICP-OES). The bioconcentration (BCF) and translocation (TF) factors were calculated by kind of metal and treatment. The BCF for the three elements was greater than 1 in all the treatments. For As, BCF varied from 5.4 to 4.0, Cd 36.5 to 19.6 and Pb 5.7 to 2.7. The TF for the three elements was lower than 1 in T2, and greater than 1 in T3 and T4. The TF range for As was 0.6 to 4.7, Cd 0.5 to 2.6 and Pb 0.3 to 3.2. E. macrostachya result to be phytoextractor, being able to accumulate and traslocate Pb, Cd and As; its capacity improved with the increase of metal concentrations in water. Los crecientes problemas de contaminación del agua han creado espacios no aptos para habitar. La fitorremediación es una técnica que utiliza plantas para descontaminar agua, suelo y aire. Por ello, se evaluó la capacidad de Eleocharis macrostachya para remediar agua contaminada con plomo (Pb), cadmio (Cd) y arsénico (As). Las plantas fueron recolectadas, se lavaron y trasplantaron en arena y se colocaron en macetas por grupos de tratamiento: T1 (testigo), T2 (As 2 mg/L, Cd 10 mg/L, Pb 20 mg/L), T3 (As 4 mg/L, Cd 100 mg/L, Pb 200 mg/L) y T4 (As 8 mg/L, Cd 200 mg/L, Pb 400 mg/L). Las macetas fueron regadas por 210 días, al final del experimento se separaron suelo y planta para su digestión y posterior análisis con un espectrofotómetro de emisión óptica con plasma de acoplamiento inductivo (ICP-OES ). Se calcularon los factores de bioconcentración (FBC) y traslocación (FT) por metal y tratamiento. El FBC para los tres elementos fue mayor a 1 en todos los tratamientos. Para As el FBC varió de 5.4 a 4.0, Cd 36.5 a 19.6 y Pb 5.7 a 2.7. El FT para los tres elementos fue menor a 1 en T2 y mayor a 1 en T3 y T4. El intervalo de FT para As fue 0.6 a 4.7, Cd 0.5 a 2.6 y Pb 0.3 a 3.2. E. macrostachya resultó ser fitoextractora, siendo capaz de acumular y traslocar Pb, Cd y As; su capacidad se incrementó con el aumento de la concentración de los metales en el agua.
DYNAMIC EVOLUTION CHARACTERISTICS AND MECHANISM OF SURROUNDING ROCK FRACTURES DURING THE REPEATED MINING OF CLOSED DISTANCE DEEP COAL SEAM
Get PDFThe disturbance mechanics behavior and mechanics mechanism of repeated mining of coal seam group are the important theoretical basis for safe mining of deep coal seam group. For the characteristics of interaction among coal seams under the condition of combined mining of coal seam group, in this paper, the spatio-temporal evolution characteristics of 3D mining stress field and the law of strata activity in repeated mining of deep coal seam group were studied by using similar material simulation and numerical simulation methods. The results showed that during the first mining, overburden mining broke the initial stress balance; part of the surrounding rock stress was released and free space was formed; rock mass moved to the direction of goaf, which released the pressure and protected the rock mass; a caving arch was formed in the overburden strata of coal seam whose arch trace was composed of the boundary line of separated strata and the fracture line of rock beam. As the working face continued to advance, the exposed strata in the arch gradually transferred and expanded to the upper strata, and the separated strata also gradually propagated upward, thus forming the periodic failure process of the caving arch. During repeated mining, the upper coal seam underwent the support and compaction process of caving, natural filling, the integrity of the main roof of the underlying coal seam was destroyed, all the interlayer strata collapsed or broke, and were connected with the goaf of the upper coal seam working face, resulting in the fractured rock mass of the goaf directly transferring load downward, and then the periodic weighting of mining was relaxed. The results have certain reference value for the combined mining of coal seams under similar conditions.The disturbance mechanics behavior and mechanics mechanism of repeated mining of coal seam group are the important theoretical basis for safe mining of deep coal seam group. For the characteristics of interaction among coal seams under the condition of combined mining of coal seam group, in this paper, the spatio-temporal evolution characteristics of 3D mining stress field and the law of strata activity in repeated mining of deep coal seam group were studied by using similar material simulation and numerical simulation methods. The results showed that during the first mining, overburden mining broke the initial stress balance; part of the surrounding rock stress was released and free space was formed; rock mass moved to the direction of goaf, which released the pressure and protected the rock mass; a caving arch was formed in the overburden strata of coal seam whose arch trace was composed of the boundary line of separated strata and the fracture line of rock beam. As the working face continued to advance, the exposed strata in the arch gradually transferred and expanded to the upper strata, and the separated strata also gradually propagated upward, thus forming the periodic failure process of the caving arch. During repeated mining, the upper coal seam underwent the support and compaction process of caving, natural filling, the integrity of the main roof of the underlying coal seam was destroyed, all the interlayer strata collapsed or broke, and were connected with the goaf of the upper coal seam working face, resulting in the fractured rock mass of the goaf directly transferring load downward, and then the periodic weighting of mining was relaxed. The results have certain reference value for the combined mining of coal seams under similar conditions
DEVELOPMENT AND VALIDATION OF THREE-DIMENSIONAL HUMAN RANGE OF MOTION MEASUREMENT SYSTEM
Get PDFThree-dimensional human range motion measurement system is developed by inertial sensor technology and wireless bluetooth acquisition technology. This paper describes the internal structure and the data processing method of the measurement system in detail. This measurement system is capable of testing the range of each joint motion, and can be easily carried to the rehabilitation hall, wards and other occasions for test and evaluation. It plays an extremely important role in its application in monitoring rehabilitation process, assessing disability, doing scientific research, and in many other fields. Three experienced teachers tested the range of motion of cervical spine, lumbar spine, right side of the shoulder, elbow, wrist, hip, knee, ankle, and other joints of ten college students. Through comparing the test results and the obtained results of this measurement system by using the method of paired samples T-test, they got the results that the bilateral significance level (Sig) was greater than 0.05, which can be considered that there were no significant differences between these two sets of results. Then it verifies the validity of the data in this system.Three-dimensional human range motion measurement system is developed by inertial sensor technology and wireless bluetooth acquisition technology. This paper describes the internal structure and the data processing method of the measurement system in detail. This measurement system is capable of testing the range of each joint motion, and can be easily carried to the rehabilitation hall, wards and other occasions for test and evaluation. It plays an extremely important role in its application in monitoring rehabilitation process, assessing disability, doing scientific research, and in many other fields. Three experienced teachers tested the range of motion of cervical spine, lumbar spine, right side of the shoulder, elbow, wrist, hip, knee, ankle, and other joints of ten college students. Through comparing the test results and the obtained results of this measurement system by using the method of paired samples T-test, they got the results that the bilateral significance level (Sig) was greater than 0.05, which can be considered that there were no significant differences between these two sets of results. Then it verifies the validity of the data in this system.
DAÑO GENÉTICO Y CITOTÓXICO PROVOCADO POR PLAGUICIDAS EN JORNALEROS QUE LABORAN EN INVERNADEROS EN ATLIXCO, PUEBLA, MÉXICO
Get PDFThe monitoring of genotoxic damage in laborers of greenhouses allows the identification of deterioration of DNA originated by working conditions. It has been suggested the use of different biological markers to evaluate the risk of occupational exposure and DNA damage, one of them is the micronucleus (MN) assay. The objective of the study was to determine the frequency of MN and nuclear abnormalities in the buccal mucosa epithelium of 40 workers of high and low technology greenhouses, who are exposed to diferent kinds of pesticides, and of 40 people not exposed to these compounds, both populations from Atlixco City, in Puebla, Mexico. The samples taken were air-dried and fixed with methanol-acetic acid. Later they were stained by the Feulgen reaction. Nuclear abnormalities were assessed by counting one thousand differentiated basal cells per participant. Comparison of biomarkers frequencies indicates higher values of nuclear abnormalities statistically significant in laborers of greenhouses, whose frequency index ratios were: 63.0 binucleate cells, 14.2 cells with condensed chromatin, 8.0 cariolitic cells, 3.8 cells pycnotic, 2.4 cells with nuclear outbreaks, and 2.3 cells with micronuclei. The highest frequency of nuclear abnormalities was determined in laborers working in low-tech greenhouses compared to high-tech greenhouses. The male population of low-tech greenhouses showed higher frequencies of pycnotic cells, micronuclei, and cells with nuclear outbreaks.El monitoreo del daño genotóxico en jornaleros de invernaderos permite identificar el deterioro del ADN originado por las condiciones laborales. Se ha sugerido el empleo de diferentes marcadores biológicos para evaluar el riesgo de exposición ocupacional y el daño al ADN, uno de los cuales es el ensayo de micronúcleos (MN). El objetivo del estudio fue determinar la frecuencia de MN y anormalidades nucleares en frotis epiteliales de mucosa bucal de 40 jornaleros de invernaderos de alta y baja tecnología, expuestos a distintas clases de plaguicidas, y en 40 personas no expuestas a estos compuestos. Ambas poblaciones residen en la ciudad de Atlixco, Puebla, México. Las muestras tomadas se secaron al aire y se fijaron con metanol-ácido acético, después se tiñeron mediante la reacción de Feulgen. Se evaluaron las anormalidades nucleares contando mil células basales diferenciadas por participante. La comparación de frecuencias de los biomarcadores indicó mayor valor estadísticamente significativo de anormalidades nucleares en jornaleros de invernaderos, cuyas relaciones de índice de frecuencia fueron: 63.0 células binucleadas, 14.2 células con cromatina condensada, 8.0 células cariolíticas, 3.8 células picnóticas, 2.4 células con brotes nucleares y 2.3 células con micronúcleos. La frecuencia mayor de anormalidades nucleares se determinó en jornaleros que laboran en invernaderos de baja tecnología en comparación con los invernaderos de alta tecnología. La población masculina de invernaderos de baja tecnología mostró mayores frecuencias de células picnóticas, con micronúcleos y con brotes nucleares
BIOSORPTION OF CADMIUM AND LEAD USING SUSPENDED AND IMMOBILIZED Enterobacter cloacae AT DIFFERENT pH
Get PDFThe aim of this work was to determine the best conditions for biomass production of the bacterium Enterobacter cloacae and for Cd and Pb retention by adsorption on the cell walls or by absorption and accumulation in the bacterial biomass. Suspended and immobilized cultures of this bacterium, acclimated to both metals, were grown for 24 h at pH 6, 7 and 9, in trypticase soy (TS) medium added with 2.73 mg/L of Cd or 16.8 mg/L of Pb. Immobilized cultures at pH 7 and 9 had the highest biomass production. Percentages of Cd retention by adsorption and absorption increased with increasing pH, but adsorption was higher in suspended while absorption was higher in immobilized cultures. Possibly because of different affinity of bacterial cells for these metals, the percentages of Pb retention were higher than those of Cd. In percentage, the highest Pb adsorption on cell walls was at pH 9, while retention by biomass decreased with increasing pH. The amount of metal retained by one g of bacterial biomass, efficiency was higher at pH 6, possibly because of the presence of dead or dying bacterial cells.The aim of this work was to determine the best conditions for biomass production of the bacterium Enterobacter cloacae and for Cd and Pb retention by adsorption on the cell walls or by absorption and accumulation in the bacterial biomass. Suspended and immobilized cultures of this bacterium, acclimated to both metals, were grown for 24 h at pH 6, 7 and 9, in trypticase soy (TS) medium added with 2.73 mg/L of Cd or 16.8 mg/L of Pb. Immobilized cultures at pH 7 and 9 had the highest biomass production. Percentages of Cd retention by adsorption and absorption increased with increasing pH, but adsorption was higher in suspended while absorption was higher in immobilized cultures. Possibly because of different affinity of bacterial cells for these metals, the percentages of Pb retention were higher than those of Cd. In percentage, the highest Pb adsorption on cell walls was at pH 9, while retention by biomass decreased with increasing pH. The amount of metal retained by one g of bacterial biomass, efficiency was higher at pH 6, possibly because of the presence of dead or dying bacterial cells.
MERCURIO EN RAÍCES AÉREAS Y ABSORBENTES DE Rhizophora mangle L. LOCALIZADA EN EL LITORAL COSTERO DE LA PROVINCIA DE EL ORO, ECUADOR
Get PDFMercury concentrations in absorbent and aerial roots of Rhizophora mangle L. were investigated in the coastline of El Oro province, Ecuador. Sampling of roots was conducted in Puerto Hualtaco, Estero Huaylá, Jambelí and Bajo Alto during the months of November 2014 (dry seasons) and January 2015 (rainy seasons). Eighty roots were collected, 10 aerial and 10 absorbent in each location. Mercury was determined using atomic absorption spectrophotometry coupled to hydride-cold vapor generation and was expressed as mg/kg of dry mass. The highest concentrations of Hg were observed during the raining season, with a value of 321.68 ± 85.59 mg/kg. The location of Puerto Hualtaco presented the highest value of Hg (382. 46 ± 273.84 mg/kg) in absorbent roots. The results showed that Hg concentration in samples of aerial and absorbing roots are characteristic of an area highly impacted by Hg. This findings demonstrate that R. mangle L. has a great capacity to incorporate Hg in its roots and can be a good biomonitor of mercury in mangrove ecosystems.Se evaluaron las concentraciones de Hg en raíces absorbentes y aéreas de Rhizophora mangle L., de cuatro zonas costeras de la Provincia El Oro, Ecuador, correspondientes a Puerto Hualtaco, Estero Huaylá, Jambelí y Bajo Alto durante los meses de noviembre-2014 (período de poca lluvia) y enero-2015 (período de lluvia). Se colectaron un total de 80 raíces, 10 aéreas y 10 absorbente en cada localidad. El Hg fue determinado mediante Espectrofotometría de Absorción Atómica Acoplado a Generación de Vapor de Hidruros en Frío y fue expresado en mg kg-1 (materia seca). Se aplicó un análisis de Mann-Whitney (W) para establecer diferencias entre las concentraciones de Hg de raíces absorbentes y aéreas y entre los períodos de muestreo. Se aplicó la prueba de Kruskal-Wallis para determinar las diferencias en el Hg de raíces entre localidades. La concentración de Hg en las raíces aéreas y absorbentes fue significativamente diferente (W=639.0; P=0.122), con valores de 243.13±91.14 mg kg-1 y 300.03±170.96 mg kg-1, para raíces aéreas y absorbentes respectivamente. Las raíces absorbentes presentaron una concentración de Hg significativamente más elevada (KW=6.059; P=0,013) durante la época de lluvia con un valor de 321.68±85.59 mg kg-1. La localidad de Puerto Hualtaco presentó el mayor valor de Hg (382.46±273.84 mg kg-1) en las raíces absorbentes. Estos hallazgos demuestran que Rhizophora mangle L. tiene una gran capacidad de incorporación de Hg y puede ser un buen biomonitor de mercurio en los ecosistemas de manglares