Revista Internacional de Contaminación Ambiental
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Organic amendments application effect on a contaminated soil with arsenic
Get PDFSoil is a non-renewable natural resource essential for obtaining food. Anthropogenic activities threaten this resource by exposing it to different pollutants, such as metals and metalloids, which can alter its functionality and threaten human health through the intake of food contaminated with these elements. The aim of this study was to evaluate the effect of two organic amendments, compost (CP) and biochar (BC) in a phytoremediation process of a soil contaminated with arsenic (As) at a dose of 60 mg/kg. For this purpose, germination tests and a greenhouse assay were carried out applying two doses of each amendment, 5 and 10% to As-contaminated soil using Lactuca sativa L. as control plant. The application of CP showed a decrease in the As bioavailability in the soil (from 1.95 mg/kg in control soil to 1.77 in CP 5% and 1.45 in CP 10%), decreasing the translocation to the aerial part and enhancing the development of plants, being this effect dose-dependent. The treatments with BC caused an increase in As bioavailability in the soil, allowing its translocation to the aerial part of the plants and affecting its development. In soil, both amendments increased organic matter content observing the greatest increases with CP. Moreover, using CP, an increase in the nutrients analyzed (N, P, K, Ca, Mg, and Na) was observed, as well as an increase in the total As content at the 10% dose. The enzymatic activity of the soils treated with CP increased significantly, whereas inhibition of most of the evaluated activities was observed with BC treatments. The application of CP led to an As immobilizing effect, decreasing As availability and preventing its translocation to plants. At the same time, it contributed to soil remediation, improving its fertility. Finally, the used BC mobilized As, which negatively affected the development of the lettuce plants, as well as the biological activity of the soil.Soil is a non-renewable natural resource essential for obtaining food. Anthropogenic activities threaten this resource by exposing it to different pollutants, such as metals and metalloids, which can alter its functionality and threaten human health through the intake of food contaminated with these elements. The aim of this study was to evaluate the effect of two organic amendments, compost (CP) and biochar (BC) in a phytoremediation process of a soil contaminated with arsenic (As) at a dose of 60 mg/kg. For this purpose, germination tests and a greenhouse assay were carried out applying two doses of each amendment, 5 and 10% to As-contaminated soil using Lactuca sativa L. as control plant. The application of CP showed a decrease in the As bioavailability in the soil (from 1.95 mg/kg in control soil to 1.77 in CP 5% and 1.45 in CP 10%), decreasing the translocation to the aerial part and enhancing the development of plants, being this effect dose-dependent. The treatments with BC caused an increase in As bioavailability in the soil, allowing its translocation to the aerial part of the plants and affecting its development. In soil, both amendments increased organic matter content observing the greatest increases with CP. Moreover, using CP, an increase in the nutrients analyzed (N, P, K, Ca, Mg, and Na) was observed, as well as an increase in the total As content at the 10% dose. The enzymatic activity of the soils treated with CP increased significantly, whereas inhibition of most of the evaluated activities was observed with BC treatments. The application of CP led to an As immobilizing effect, decreasing As availability and preventing its translocation to plants. At the same time, it contributed to soil remediation, improving its fertility. Finally, the used BC mobilized As, which negatively affected the development of the lettuce plants, as well as the biological activity of the soil
An intelligent control method for the spraying amount of a self-propelled weeder based on a dynamic programming algorithm
Get PDFWhen the self-propelled weeder reaches an obstacle, the amount of pesticide spraying does not change according to the actual situation, leading to an application imbalance. Therefore, an intelligent control method of spraying output of a self-propelled weeder based on a dynamic programming algorithm (DPA) was proposed. The dynamic norm algorithm transformed obstacle avoidance path planning into a multi-stage decision-making problem. The obstacle avoidance path was planned, and the pesticide dosage control equation was designed by using the PID control algorithm to realize the obstacle avoidance and variable application of self-walking weed killer. The experimental results show that the designed self-walking weeder can effectively avoid obstacles, and the maximum average dosage error is 1.4%. Therefore, the method can effectively apply the dosage according to the actual situation and guarantee the balance of spraying quantity.When the self-propelled weeder reaches an obstacle, the amount of pesticide spraying does not change according to the actual situation, leading to an application imbalance. Therefore, an intelligent control method of spraying output of a self-propelled weeder based on a dynamic programming algorithm (DPA) was proposed. The dynamic norm algorithm transformed obstacle avoidance path planning into a multi-stage decision-making problem. The obstacle avoidance path was planned, and the pesticide dosage control equation was designed by using the PID control algorithm to realize the obstacle avoidance and variable application of self-walking weed killer. The experimental results show that the designed self-walking weeder can effectively avoid obstacles, and the maximum average dosage error is 1.4%. Therefore, the method can effectively apply the dosage according to the actual situation and guarantee the balance of spraying quantity
Estudio del posible impacto de los cruceros turísticos en la calidad del agua del Puerto Buenos Aires, Argentina
Get PDFWater quality in ports can be affected by contamination from land and/or water. Cruise ships are floating cities with capacity for more than 5000 people, generating a large amount of wastewater. Cruise vessels have internationally regulated treatment plants, with different discharge quality standards. The aims of the current study were to evaluate the characteristics of cruise ships, their treatment plants and their possible impact on the water quality of the Port Buenos Aires, Argentina. Eight samplings were carried out between October 2018 and March 2019 in docks A, B and C, as well as in the Río de la Plata (RDP). In addition, information was collected from the cruise ships moored at the time of the sampling. Twenty-one cruise ships were registered, transporting more than 57 000 people. Dock B was the one that received the largest number of cruise ships (11) and passengers (39 562). The 90.5 % of the cruise ships comply with the MEPC.2 (VI) treatment regulations, 9.5 % with the MEPC.159 (55) and none with the MEPC.227 (64), the most restrictive. This might be related to the fact that the fleet that operates in this zone of South America is older than the one that operates in special zones with stricter legislation. Significant differences were observed between the quality of port water and the RDP, however, there is no evidence of a direct effect from the cruises. For future research, it is recommended to characterize the effluents from the treatment plants and their possible effect on the port water.La calidad del agua en los puertos puede verse afectada por contaminación proveniente desde tierra y/o desde el agua. Los cruceros son verdaderas ciudades flotantes, con capacidad para más de 5000 personas, generando gran cantidad de aguas sucias. Los buques poseen plantas de tratamiento reguladas internacionalmente, con distintos estándares de calidad de descarga. El objetivo del trabajo fue evaluar las características de los cruceros, de sus plantas de tratamiento y su posible impacto en la calidad del agua del Puerto Buenos Aires, Argentina. Se realizaron ocho muestreos entre octubre de 2018 y marzo de 2019 en las dársenas A, B y C del puerto y en el Río de la Plata (RDP), además se recopiló información de los cruceros amarrados al momento de los muestreos. Se censaron 21 cruceros, transportando más de 57 000 personas. La dársena B fue la que recibió mayor cantidad de cruceros (11) y personas a bordo (39 562). El 90.5 % de los cruceros cumplió con la normativa MEPC.2 (VI), el 9.5 % con la MEPC.159 (55) y ninguno con la MEPC.227 (64), la más restrictiva. Esto podría estar relacionado con que la flota que opera en esta zona de Sudamérica es más antigua que la que opera en zonas especiales con legislación más estricta. Se observaron diferencias significativas entre la calidad del agua portuaria y la del RDP. Sin embargo, no existe evidencia de un efecto directo por parte de los cruceros. Para futuras investigaciones se recomienda caracterizar los efluentes de las plantas de tratamiento y su posible efecto en el agua del puerto
Urban WRF-Chem evaluation over a high-altitude tropical city
Get PDFMorphology and grid resolution are important aspects that need to be considered in urban modeling applications, since together with buildings they induce a direct effect on wind and dispersion of pollutants over urban areas. In this study, we evaluate high-resolution simulations of a multi-layer urban canopy model (UCM) based on a local climate zone (LCZ) classification coupled to the Weather Research and Forecasting model with Chemistry (WRF-Chem), in the local meteorological conditions and air quality pollutants of a highly urbanized megacity. This modeling system, known as Building Effect Parameterization (BEP) considers the effects of buildings’ vertical and horizontal surfaces on the momentum that considerably impacts the lower part of the urban boundary layer (UBL). Simulations of the urbanized model (WRFu) were compared against a Noah land surface model (Noah LSM) with no urban physics (WRF) for the same period. It was observed that the LCZ classification and urban parameterization coupled to the model have a direct influence in meteorological parameters and pollutant concentrations. Urban simulations of temperature and wind speed showed higher sensitivity to initial and boundary conditions, increasing the correlation with observations and reducing the bias error. An important observation is that emissions drive air quality concentrations despite the improvements in local meteorology.Morphology and grid resolution are important aspects that need to be considered in urban modeling applications, since together with buildings they induce a direct effect on wind and dispersion of pollutants over urban areas. In this study, we evaluate high-resolution simulations of a multi-layer urban canopy model (UCM) based on a local climate zone (LCZ) classification coupled to the Weather Research and Forecasting model with Chemistry (WRF-Chem), in the local meteorological conditions and air quality pollutants of a highly urbanized megacity. This modeling system, known as Building Effect Parameterization (BEP) considers the effects of buildings’ vertical and horizontal surfaces on the momentum that considerably impacts the lower part of the urban boundary layer (UBL). Simulations of the urbanized model (WRFu) were compared against a Noah land surface model (Noah LSM) with no urban physics (WRF) for the same period. It was observed that the LCZ classification and urban parameterization coupled to the model have a direct influence in meteorological parameters and pollutant concentrations. Urban simulations of temperature and wind speed showed higher sensitivity to initial and boundary conditions, increasing the correlation with observations and reducing the bias error. An important observation is that emissions drive air quality concentrations despite the improvements in local meteorology
Investigation of factors affecting removal of arsenic from polluted water using iron-based particles: Taguchi optimization design
Get PDFIntensive research efforts have been followed to remove arsenic (As) from contaminated water to provide potable water to millions living in different countries. Adsorption is a simple and efficient way for arsenic contamination purification in water, with a pressing challenge to find a cheap and efficient adsorbent. The present paper deals with optimizing various batch parameters for the adsorption of As from solution by synthesized iron-based particles (hematite, magnetite, and zero-valent iron (ZVI)) nanomaterials using Taguchi’s optimization methodology. Taguchi’s (L27) orthogonal design with six effective factors, namely: initial As concentration, pH, contact time, adsorbent type, size, and dose, was applied for the multivariate optimization in adsorption studies for As to maximize the adsorption capacity along with the signal-to-noise ratio. The equilibrium studies revealed that the data were well described by Freundlich isotherm. The results showed that initial As concentration was the most important parameter in the adsorption process.Intensive research efforts have been followed to remove arsenic (As) from contaminated water to provide potable water to millions living in different countries. Adsorption is a simple and efficient way for arsenic contamination purification in water, with a pressing challenge to find a cheap and efficient adsorbent. The present paper deals with optimizing various batch parameters for the adsorption of As from solution by synthesized iron-based particles (hematite, magnetite, and zero-valent iron (ZVI)) nanomaterials using Taguchi’s optimization methodology. Taguchi’s (L27) orthogonal design with six effective factors, namely: initial As concentration, pH, contact time, adsorbent type, size, and dose, was applied for the multivariate optimization in adsorption studies for As to maximize the adsorption capacity along with the signal-to-noise ratio. The equilibrium studies revealed that the data were well described by Freundlich isotherm. The results showed that initial As concentration was the most important parameter in the adsorption process
Calidad microbiológica, física y química del agua empleada en establecimientos lácteos artesanales de Tandil, Argentina
Get PDFDairy production requires an abundant good-quality water supply. This research aimed to study water quality in eight artisanal dairies from Tandil, Buenos Aires province, Argentina, which use groundwater resource. Data were collected and water samples were taken in different visits from 2016 to 2020. The analysis showed that 41% of the samples obtained from the perforations did not meet the physical and chemical criteria established by the Argentine Food Code for drinking water, mainly due to excess salts such as nitrates or salts that cause hardness, and 41 % were not suitable according to microbiological criteria, mainly due to a high total coliform count (TC). Likewise, high TC counts and the presence of Escherichia coli and Pseudomonas aeruginosa were evidenced in water samples obtained from dairy farms (54 % CT, 19 % E. coli and 12 % P. aeruginosa) and factories (33% CT, 7% E. coli and 2% P. aeruginosa). Sulfite-reducing clostridia, enterococci, and Salmonella spp. were also detected in some samples. Despite the good quality of the aquifer in the region, these results evidenced sites with point contamination, which could be related to the infiltration of the discharged effluents and the disposal of excreta in the vicinity of the wells. The use of water with microbiological and/or physical and chemical quality problems in these establishments can negatively affect the quality of the products and constitute a risk to the health of consumers.La elaboración de productos lácteos requiere agua de calidad potable, de tal manera que no comprometa la inocuidad del producto. El objetivo del presente trabajo fue investigar la calidad del agua en ocho establecimientos lácteos de elaboración artesanal del municipio de Tandil, provincia de Buenos Aires, Argentina, que utilizan el recurso subterráneo. Se recolectaron datos y se tomaron muestras de agua en diferentes visitas desde 2016 a 2020. Los análisis evidenciaron que un 41 % de las muestras obtenidas de las perforaciones no cumplieron con los criterios físicos y químicos establecidos por el Código Alimentario Argentino para agua potable, principalmente por excesos de nitratos o las sales causantes de la dureza; y un 41 % no fueron aptas según criterios microbiológicos, principalmente por alto recuento de coliformes totales (CT). Asimismo, se evidenciaron altos recuentos de CT, presencia de Escherichia coli y de Pseudomonas aeruginosa en muestras obtenidas de grifos en sala de ordeño (54 % de las muestras con CT, 19 % con E. coli y 12% con P. aeruginosa) y en queserías (33% de las muestras con CT, 7% con E. coli y 2% con P. aeruginosa). También se detectaron clostridios sulfito reductores, enterococos y Salmonella spp. en algunas muestras. Si bien la calidad del acuífero de la región es buena, estos resultados evidenciaron sitios con contaminación puntual que estaría relacionada con la infiltración de los efluentes vertidos y la disposición de excretas cercanas a las perforaciones. El empleo de agua con problemas de calidad microbiológica y/o física y química en establecimientos elaboradores, puede afectar negativamente la calidad de los productos y constituir un riesgo para la salud de los consumidores
Water ecosystem health evaluation and influencing factors analysis of an urban river: A case study at Beiyunhe River, Northern China
Get PDFThe Beiyunhe River is a typical urban river in northern China, and the health status of its ecosystem is degraded by urbanization. To evaluate this health status, a survey was performed throughout the basin. Thirteen indexes were selected to construct an ecosystem health evaluation system, and a composite index method was used to quantify the Beiyunhe River’s ecosystem health. Redundancy analysis (RDA) was used to detect the key factors influencing ecosystem health. The results showed that the river’s health status was mostly moderate: of the 38 surveyed points, the health status of 10% was Good, 47% was Average, 40% was Poor, and 3% was Very Poor. The upper and middle reaches were in better health than the lower reaches, and the main stream health was better than the tributaries. Among the tributaries, Bahe River (upper and middle reaches) had the best health status, whereas Fenghe River (lower reaches) had the worst. RDA showed that the ratio of hardening of the river, number of water-blocking structures (gates and dams), and population density in the catchment area were the key factors affecting the health of the Beiyunhe River ecosystem. This study can be used as a reference for the evaluation of the health of urban river ecosystems.The Beiyunhe River is a typical urban river in northern China, and the health status of its ecosystem is degraded by urbanization. To evaluate this health status, a survey was performed throughout the basin. Thirteen indexes were selected to construct an ecosystem health evaluation system, and a composite index method was used to quantify the Beiyunhe River’s ecosystem health. Redundancy analysis (RDA) was used to detect the key factors influencing ecosystem health. The results showed that the river’s health status was mostly moderate: of the 38 surveyed points, the health status of 10% was Good, 47% was Average, 40% was Poor, and 3% was Very Poor. The upper and middle reaches were in better health than the lower reaches, and the main stream health was better than the tributaries. Among the tributaries, Bahe River (upper and middle reaches) had the best health status, whereas Fenghe River (lower reaches) had the worst. RDA showed that the ratio of hardening of the river, number of water-blocking structures (gates and dams), and population density in the catchment area were the key factors affecting the health of the Beiyunhe River ecosystem. This study can be used as a reference for the evaluation of the health of urban river ecosystems
Elucidación del mecanismo de remoción de arsénico en disolución acuosa con residuos metalúrgicos
Get PDFWe present the elucidation mechanism of arsenite removal with slags through the evaluation of five materials: A1, C1, N1 (steel industry), M1 (lead industry), and M2 (iron industry), all of them with different surface areas pore diameter, and chemical and mineralogical composition. The slags were physically characterized, determining surface area (1.6 to 10 m2/g) and zero charge point (5.5); chemically by X ray fluorescence (XRF) mainly identifying Si, Ca and Fe, and the release of potentially toxic elements by leaching at different pH´s (5, 7 and 9) was ruled out. The mineralogy determined by X ray difraction (XRD) showed iron compounds. The removal of arsenite was evaluated at laboratory level by means of a 2k experimental design in synthetically contaminated samples. Agitation time, amount of slag and initial concentration of arsenite were evaluated. The optimal removal conditions were: 250 mg of slag, 10 mg/L of arsenite, and agitation time of 60 min. The C1 slag removed more than 90 % of the initial arsenite, and the proposed fixation mechanism could be a chemisorption at heterogeneous sites, as well as through intraparticle diffusion. XRD and infrarred (IR) spectroscopy analyses of the slag after arsenic fixation showed that there is a direct interaction of arsenite with iron.En este trabajo se busca elucidar el mecanismo de remoción de arsenito con escorias mediante la evaluación de cinco materiales: A1, C1, N1 (industria del acero), M1 (industria del plomo) y M2 (industria del hierro), todos ellos con diferente área superficial, tamaño de poro, y composición química y mineralógica. Las escorias se caracterizaron físicamente, determinándose su área superficial (1.6 a 10 m2/g), tamaño de poro (6.5 a 16.8 nm) y punto de carga cero (5.5); químicamente por fluorescencia de rayos X (FRX), identificándose mayoritariamente Si, Ca y Fe, y se descartó la liberación de elementos peligrosos por lixiviación a distintos pH (5, 7 y 9). La mineralogía determinada por difracción de rayos X (DRX) muestra compuestos de hierro. La remoción de arsenito se evaluó mediante un diseño experimental 2k en muestras contaminadas sintéticamente en el laboratorio. Se evaluaron el tiempo de agitación, la cantidad de escoria y la concentración inicial de arsenito. Las condiciones óptimas de remoción fueron: 250 mg de escoria, 10 mg/L de arsenito y 60 min de agitación. La escoria C1 removió más del 90 % del arsenito inicial y se sugiere que la fijación ocurre por quimisorción en sitios heterogéneos del material, así como a través de la difusión intrapartícula. Los análisis de espectroscopía de DRX e infrarroja (IR) de la escoria después de fijar arsénico, muestran que existe una interacción directa del arsenito con el hierro
Design of highway pavement earthquake damage prediction method considering horizontal earthquake force
Get PDFDue to the influence of geographical environment and horizontal seismic force, it is difficult to predict the seismic damage of urban highway pavement. In addition, poor engineering characteristics will cause damage to the stability of the subgrade and extremely easy to deformation. The above situation has become an important problem in highway construction. To improve the accuracy of earthquake damage prediction of highway pavement, a method of earthquake damage prediction considering horizontal seismic force is proposed. This method is based on the fuzzy comprehensive evaluation, taking the highway bridge, subgrade and pavement, roadside environment and highway tunnel as the main factors, and establishing the post-earthquake damage evaluation model of the highway system. Based on the analysis of the relevant data, the power polynomial prediction model is proposed, and the feasibility and parameter determination method of the power polynomial are analyzed. The stability of highway pavement under earthquake is predicted. The results show that the design method can predict the seismic damage of highway pavement. In addition, the proposed surface model can also simulate the settlement value and predict the settlement law.Due to the influence of geographical environment and horizontal seismic force, it is difficult to predict the seismic damage of urban highway pavement. In addition, poor engineering characteristics will cause damage to the stability of the subgrade and extremely easy to deformation. The above situation has become an important problem in highway construction. To improve the accuracy of earthquake damage prediction of highway pavement, a method of earthquake damage prediction considering horizontal seismic force is proposed. This method is based on the fuzzy comprehensive evaluation, taking the highway bridge, subgrade and pavement, roadside environment and highway tunnel as the main factors, and establishing the post-earthquake damage evaluation model of the highway system. Based on the analysis of the relevant data, the power polynomial prediction model is proposed, and the feasibility and parameter determination method of the power polynomial are analyzed. The stability of highway pavement under earthquake is predicted. The results show that the design method can predict the seismic damage of highway pavement. In addition, the proposed surface model can also simulate the settlement value and predict the settlement law
Optimization of Fermentation Process for Apricot Vinegar
Get PDFTo study the optimal fermentation conditions of Prunus armeniaca L. (apricot), single factor experiments and orthogonal experiments were implemented. The experimental results demonstrate that the optimum alcoholic fermentation conditions are: sugar degree a9%, inoculation quantity of yeast at 0.7%, fermentation temperature at 30 ºC. The alcohol degree could reach 7.56%; the optimum acetic fermentation conditions are: alcohol degree at 7%, inoculation quantity of acetic acid bacillus at 0.8%, fermentation temperature at 32 ºC, fermentation time at 7 days, and the total acid content could be obtained as 6.78 g/100 mL. Under such conditions, the fruit vinegar has rich Prunus armeniaca L. flavor and pure taste.To study the optimal fermentation conditions of Prunus armeniaca L. (apricot), single factor experiments and orthogonal experiments were implemented. The experimental results demonstrate that the optimum alcoholic fermentation conditions are: sugar degree a9%, inoculation quantity of yeast at 0.7%, fermentation temperature at 30 ºC. The alcohol degree could reach 7.56%; the optimum acetic fermentation conditions are: alcohol degree at 7%, inoculation quantity of acetic acid bacillus at 0.8%, fermentation temperature at 32 ºC, fermentation time at 7 days, and the total acid content could be obtained as 6.78 g/100 mL. Under such conditions, the fruit vinegar has rich Prunus armeniaca L. flavor and pure taste