Nitrate and phosphate leaching in a phaeozen soil treated with biosolids, composted biosolids and inorganic fertilizers

The use of organic wastes in agriculture may increase the production of crops by incorporating organic matter and nutrients into the soil, and by improving its physical characteristics; however, this use may cause environmental problems such as the leaching of certain ions. The objective of this study was to establish possible nitrogen and phosphorus leaching under real field conditions in Phaeozem soils. The experimental work was performed in a corn (Zea mays L.) field where three plots were conditioned with inorganic fertilizer, three plots with 4.5 Mg ha 1 of biosolids on dry basis, and three plots with the same amount of composted biosolids. The quality of biosolids and composted biosolids complied with the Mexican Official Standards. Soil water samples were collected with suction cups during two agricultural cycles and were analysed. Soil samples were also taken and analysed. The N–NO3 concentrations in soil water fluctuated between 0.9 and 98 mg L 1 in the composted biosolid treatment, between 0.7 and 64 mg L 1 in the biosolid treatment, and between 1 and 61 mg L 1 in the inorganic fertilizer treatment. The maximum concentration of N–NO2 and N–NH3 in soil water was 1.02 and 2.65 mg L 1, respectively. The greatest percentage of nitrogen leached is produced when inorganic fertilizer is used (37.4% and 24.0% N leached in the first and second years, respectively), followed by composted biosolids (17.1% and 13.5% N leached in the first and second years, respectively) and last by biosolids (11% for both years). This difference could be related to the form in which nitrogen is present in the fertilizers, while commercial fertilizer is as inorganic nitrogen, organic wastes are basically presented as organic nitrogen. The maximum PO3 4 concentration in soil water was 1.9 mg L 1 in the composted biosolid treatment, 1.7 mg L 1 in the biosolid treatment and 0.9 mg L 1 in the inorganic fertilizer treatment. The estimated percentage of leached phosphorus was less than 1% for all treatments. The minimum leaching that occurred seemed to be due to a sorption–precipitation process

Removal of groundwater arsenic using a household filter with iron spikes and stainless steel

Arsenic (As) in groundwater for domestic use poses a worldwide threat to public health, most notably in rural areas. The aims of this study were: first, determine groundwater composition in a mining area in central Mexico (Huautla); second, assess As exposure through human groundwater consumption and; third, develop and test a household filter to obtain drinking water for these rural communities. From the 17th century through the 1990s, mines in the area produced Ag-galena and sphalerite from volcanic rock. Groundwater flooded the mines when they were abandoned due to low silver prices. Local households now use the water to meet domestic needs.Water from the mines was found to have high As content (0.04e0.26 mg L_1) and Fe, Mn, Pb and Cd were also above Mexican drinking water standards and WHO guidelines. All the population in the Huautla community was exposed to the metalloid through water used in food preparation. The best As removal was obtained with a filter using oxidized commercial fiber (HCl 2N as oxidant).Concentrations in the effluent were below Mexican drinking water standards (0.025 mg As L_1 water) during the 105-day (2520 h) filter operation, with a maximum As removal efficiency of 95.4%. The household filter was simple, low-cost and may be very attractive for As removal in rural areas in developing countries

Groundwater pollution by arsenic and other toxic elements in an abandoned silver mine, Mexico

This study evaluated the impact of an abandoned Ag mine on the quality of surface and groundwater. The mining site of Huautla is in south Morelos State, central Mexico. Ag–Pb–Zn and Au–Cu sulfide ores were mined in the district. The ores were characterized by the presence of Ag, galena (PbS), sphalerite (ZnS), and stromeyerite (CuAgS). Ag was the metal of greater interest. Other metals included Cu, Pb, Zn, and Au. Mining activities stopped in the early 1990s when the market price of Ag decreased; the abandoned mines then were flooded by rising groundwater levels. Because of the urgent demand for water by the inhabitants in the area, this water has been used as drinking water and as waterholes for livestock. Water sampling points included abandoned mines (Ame´rica, Paja´ro, Santiago, Tlachichilpa, and San Francisco), dams, and dug wells. The greatest concentrations of As and other toxic chemical elements (Fe, Mn, Pb, Cd, F) were detected in groundwater samples from flooded mines. The presence of these elements was related to the rock– water interaction process. The oxidation of sulfides appears to be the cause of increased metal concentrations in groundwater samples from flooded mine. Other posible water–rock interaction processes that can control the presence of arsenic in groundwater were the adsorption of arsenic in iron oxyhydroxides, the adsorption in carbonates, and/or coprecipitation with calcite. In the case of the San Francisco and Ame´rica mines, the oxidation conditions, low correlation of As with SO4 2- and Fe2?, and concentrations of silica indicate that the presence of As in the groundwater could be due also to competition for adsorption site

Groundwater optimization model for sustainable management of the Valley of Puebla aquifer, Mexico

The Valley of Puebla aquifer (VPA), at the central region of Mexico, is subject to intensive exploitation to satisfy the urban and industrial demand in the region. As a result of this increased exploitation, a number of state and federal agencies in charge of water management are concerned about the problems associated with the aquifer (decline of groundwater table, deterioration in water quality, poor well productivity and increased pumping and water treatment costs). This study presents a groundwater management model that combines ‘‘MODFLOW’’ simulation with optimization tools ‘‘MODRSP’’. This simulation–optimization model for groundwater evaluates a complex range of management options to identify the strategies that best fit the objectives for allocating resources in the VPA. Four hypothetical scenarios were defined to analyze the response of the hydrogeological system for future pumping schemes. Based on the simulation of flow with the MODFLOW program, promising results for the implementation of the optimization of water quantity were found in scenarios 3 and 4. However,upon comparison and analysis of the feasibility of recovery of the piezometric level (considering the policy of gradual reductions of pumping), scenario 4 was selected for optimization purposes. The response functions of scenario 4 were then obtained and optimized, establishing an extraction rate of 204.92 millions of m3/year (Mm3/year). The reduction in groundwater extraction will be posible by substituting the volume removed by 35 wells (that should be discontinued) by the same volume of water from another source

Simulación de diferentes alternativas de gestión de los recursos hídricos del acuífero de Puebla-Atoyac

La demanda de agua subterránea en el acuífero de Puebla-Atoyac, localizado en la región central de la República Mexicana se ha incrementado. Ante esto, organismos estatales y federales encargados de la gestión del agua están preocupados por la problemática que presenta el acuífero de Puebla-Alto Atoyac (descenso de nivel piezométrico, deterioro de la calidad del agua, bajo rendimiento de los pozos, agrietamiento del terreno y mayores costos de bombeo y tratamiento), resultado de una mayor explotación. Este estudio presenta un modelo de simulación en la plataforma MODFLOW, que evalúa cuatro escenarios hipotéticos que se definieron para analizar la respuesta del sistema hidrogeológico para los esquemas de bombeo futuros. Se encontraron resultados prometedores para la asignación del recurso en los escenarios 3 y 4. Sin embargo, en la comparación y el análisis de la viabilidad de la recuperación del nivel piezométrico (teniendo en cuenta la política de reducciones graduales de bombeo), se seleccionó el escenario 4 como mejor alternativa

Evaluación de la calidad del agua subterránea mediante la utilización del índice CCME-WQI, en el acuífero del Valle de Puebla

contraste con el agua superficial, los cambios en su cantidad y calidad frecuentemente son muy lentos así como difíciles de revertir (Foster et al., 2006). Por lo tanto, la evaluación de la calidad del agua se convierte en una actividad imprescindible, a la vez que vigilar periódicamente dicha calidad, ya que con base en esta información sobre la calidad del agua se pueden definir estrategias para la protección y remediación de acuíferos. Instrumentos útiles para este proceso de evaluación son los llamados índices; un índice es una de las herramientas más eficaces para transmitir información sobre la calidad del agua a las comunidades de usuarios, a los responsables del manejo y a las autoridades encargadas de la toma de decisiones, así como al público en general. Para evaluar de manera integral dicha calidad se utilizó un índice desarrollado por Canadian Council of Ministers of the Environment-Water Quality Index (CCME-WQI); que proporciona un marco matemático para la evaluación de la calidad del agua en combinación con las condiciones marcadas como criterios ó límites de calidad. Este índice es flexible con respecto al tipo y número de variables a utilizar en la evaluación, ya que permite seleccionar las variables de interés dependiendo de las características y de los objetivos de aprovechamiento, conservación y cumplimiento con la normatividad (CCME, 2001)

Calidad físico-química y microbiológica del agua en parques acuáticos. Hidrobiológica

El propósito de esta investigación fue analizar la evolución de la calidad del agua en un parque acuático determinando niveles de deterioro y causas probables; para el estudio se analizaron diferentes parámetros determinando presencia de microorganismos midiendo procesos de deterioro, con el fin de proponer sistemas de control de calidad del agua para estos establecimientos. Como zona de estudio se eligió el estado de Morelos, México, el cual cuenta con cuatro parques acuáticos. La investigación analizó uno de estos parques, dividiéndose así: Fase 1) Muestreo del agua en la entrada y salida del parque, analizando parámetros fisicoquímicos y microbiológicos; y Fase 2) Evaluación operativa en seis piscinas del parque acuático, valorándose la conductividad eléctrica, sólidos disueltos totales (SDT), pH, color, turbiedad y cloro residual. Los resultados fueron analizados con Normas Oficiales Mexicanas para determinar si existe o no deterioro en la calidad del recurso en procesos operativos del parque. La Fase 1 dio como resultados elevados niveles en grasas y aceites (19.0 mg/L), color (100 UPt-Co), coliformes fecales (1.15.104 NMP 100 mL) y coliformes totales (1.70.105 NMP/100 mL). La Fase 2 mostró elevados valores de pH (7.9-8.4), disminuyendo eficiencia en la desinfección y comportamiento diferenciado en conductividad y SDT en piscinas con sistemas de filtrado. Como conclusiones se determinó que la calidad del agua en parques acuáticos debe controlarse en paralelo con la operatividad en piscinas, los procesos de cloración deben estandarizarse, que los usuarios son responsables del deterioro y que es necesaria la generación de un Sistema de Gestión Ambiental

Hydrogeochemistry and water-rock interactions in the urban area of Puebla Valley aquifer (Mexico).

The urban area of Puebla Valley aquifer is seated in Puebla City and neighbor municipalities. Puebla is the fourth largest city in Mexico, where there are significant industrial zones and a large population. Water needs are almost exclusively met by groundwater, which has brought intense exploitation of groundwater resources and water quality degradation. The present study investigates the hydrogeochemical changes in groundwater, particularly focuses on the chemical changes produced by upwelling mineralized water. These concentrations may represent potential risks to the health of the population. The groundwater presented five types of families Ca-HCO3, Mg-HCO3, Mix-HCO3, HCO3-Ca-SO4 and Ca-SO4. The high concentrations of sulphates, calcium and magnesium are reflected in high TDS and Total Hardness. The samples collected showed detectable concentrations of F−, Fe, Mn, Ba, Sr, Cu, Zn, B and Li. The limitations for its use as drinking water are given by the high values of TDS, sulphates, total hardness and Mn. Geochemical modeling using Geochemist's Workbench (GWB) and PHREEQC software enabled the computation of the saturation index of mineral phases with ions in solution and speciation ions. Groundwater was initially in equilibrium with calcite; however, due to the changes in hydrogeological conditions, gypsum and dolomite are being dissolved until new equilibrium conditions are met. The additional calcium and carbonate in the water causes calcite to become oversaturated and to precipitate. Evidence of dedolomitization reactions and common ion effect is illustrated by concurrent increases in calcium and magnesium concentrations in the groundwater

Heavy metals in soil treated with sewage sludge composting, their effects on yield and uptake of broad bean seeds (Vicia faba, L.)

The final use that may be given to biosolids that result from the treatment of residual municipal waters depends on their physicochemical and microbiological characteristics. Their organic matter content and wealth of essential elements may allow their use for agricultural fertilization purposes. The objective of this research project was to evaluate the physicochemical interactions between soil treated with biosolids and compost from municipal residual waters, and the nutritional parameters of broad bean seeds (Vicia faba L.). The studied area is located in the central region of the Mexican Republic. The biosolids were treated with aerated static pile composting. The experimental work was performed in the area surrounding the East Toluca Macroplant, where nine 2 × 3m plots were defined and distributed in a Latin square; 3 plots were used as controls (without conditioning), 3 were conditioned with 4.5Mgha−1 of biosolids on a dry base, and 3 were conditioned with the same amount of compost. The parameters determined for biosolids, compost, and soil were: pH, electrical conductivity (EC), organic matter (OM), total nitrogen, available phosphorus, cation exchange capacity (CEC), exchangeable cations (Ca, Mg, Na and K), total and available heavy metals (Cd, Cr, Cu, Ni and Zn); for the plant: height reached, green seeds productivity and yield per treatment (ton ha−1); for the seeds: humidity, ashes, fiber, fats, protein, starch and total and available heavy metals (Cd, Cr, Cu, Ni and Zn). pH was slightly acid in soil treated with biosolids (6.71). OM and CEC did not represent significant differences. Total concentrations of Cr, Zn, Ni and Cu in soil presented significant differences (p < 0.05) between treated soil and the control, Cd was not detected. Cu was the most available metal in soil treated with compost (15.31%), Cd and Cr were not detected. The plants had higher growth rates with biosolids (112.22 cm) and compost (103.73 cm); higher Green broad bean productivity and higher seed yield, especially in plots containing biosolids, which had rates three times higher than the control. In regards to broad bean seeds, content of ashes, fiber, fats, protein, starch and heavy metals (Cu, Ni and Zn), there were no significant differences between the treatments. Cd and Cr were not detected. In conclusion, it has been proven that the use of biosolids and compost studied in this broad bean crop do not involve an environmental risk, and thus give way to a solution to the problem of final disposition of biosolids in the region

Calidad físico-química y microbiólogica del agua en parques acuáticos

El propósito de esta investigación fue analizar la evolución de la calidad del agua en un parque acuático determinando niveles de deterioro y causas probables; para el estudio se analizaron diferentes parámetros determinando presencia de microorganismos con el fin de proponer sistemas de control de calidad del agua para estos establecimientos. Como zona de estudio se eligió el estado de Morelos, México, el cual cuenta con cuatro parques acuáticos. La investigación analizó uno de estos parques, dividiéndose así: Fase 1) Muestreo del agua en la entrada y salida del parque, analizando parámetros fisicoquímicos y microbiológicos; y Fase 2) Evaluación operativa en seis piscinas del parque acuático, valorándose la conductividad eléctrica, sólidos disueltos totales (SDT), pH, color, turbiedad y cloro residual. Los resultados fueron analizados con Normas Oficiales Mexicanas para determinar si existe o no deterioro en la calidad del recurso en procesos operativos del parque. La Fase 1 dio como resultados elevados niveles en grasas y aceites (19.0 mg/L), color (100 UPt-Co), coliformes fecales (1.15.10(4) NMP 100 mL) y coliformes totales (1.70.10(5) NMP/100 mL). La Fase 2 mostró elevados valores de pH (7.9-8.4), disminuyendo eficiencia en la desinfección y comportamiento diferenciado en conductividad y SDT en piscinas con sistemas de filtrado. Como conclusiones se determinó que la calidad del agua en parques acuáticos debe controlarse en paralelo con la operatividad en piscinas, los procesos de cloración deben estandarizarse, que los usuarios son responsables del deterioro y que es necesaria la generación de un Sistema de Gestión Ambiental