Efecto de la temperatura del agua sobre la constante de velocidad de reacción de los contaminantes en un humedal construido para el tratamiento de aguas residuales porcícolas

La temperatura es un factor importante en los procesos que se llevan a cabo en los sistemas biológicos. En los humedales la capacidad de remoción de contaminantes está delimitada por factores ambientales. El objetivo fue determinar el efecto de la temperatura del agua sobre la constante de velocidad de reacción de contaminantes en un humedal de flujo superficial construido (HFSC) para la remoción de contaminantes en aguas residuales porcícolas. El HFSC consistió en un canal de 9 m de longitud por 3 m de ancho, recubierto con geo-membrana de alta densidad (4 mm). El lecho del HFSC consistió en una capa de 30 cm de arena y arcilla, con vegetación nativa del área de estudio. Se llevaron a cabo 12 corridas experimentales entre enero de 2014 y diciembre de 2015, con un tiempo de retención hidráulico (TRH) de 10 días. La remoción promedio de la demanda química de oxígeno (DQO) fue de 75 y 74 %,  el promedio de remoción de nitrógeno (amonio) NH3-N de 65 y 69 %, mientras que el nitrógeno total (NT) presentó promedio de remoción de 69 y 63 %, mientras que la remoción del fósforo total (PT) presentó valores de 75 y 73 % en 2014 y 2015 respectivamente. La temperatura del agua durante la fase experimental osciló entre 13 y 22 °C. La remoción del NH3-N mostró la mayor dependencia de la temperatura del agua con valores de R2=0.8787 en 2014 y R2=0.8957 en 2015. La constante de reacción volumétrica (kv d-1) en 2014 osciló de 0.041 a 0.185 d-1 con una temperatura promedio en el humedal de 13 a 21 °C. Mientras k presentó un valor promedio de 2.60 cm d-1 en 2014, y en 2015 el valor obtenido fue de 3.22 cm d-1. Fue evidente que el valor de kvaumentó conforme la temperatura del agua se incrementó, lo cual indica que este factor tiene un efecto directo en la remoción del NH3-N

Nutrient removal prediction using hyperspectral reflectance indices and modeling for a pilot constructed channel treatment wetland

The rapid assessment of treatment wetland performance is an important goal to help optimize nutrient removal and pollution mitigation in the design and implementation of treatment channel wetlands technologies. Four pilot-scale surface-flow channel wetlands were constructed to evaluate the potential for treatment of simulated agricultural runoff in the South Texas environment; two channel wetlands were vegetated and the other two were unvegetated and used as a control. The system was operated at four days of hydraulic retention time to evaluate the effect of three different water depths (3, 6 and 9 inches). The results demonstrated a high removal for Nitrogen species in the vegetated channel wetlands, about 85% for TKN, 58% for Nitrates and 97% for ammonia, while the removal of TP removal was about 33% and Orthophosphate removal about 45%. In addition, field spectral measurements using a portable spectroradiometer which acquires continuous spectra from 300-1100 nm were completed. Specific PRI, NDVI and CI vegetation spectral indices were computed from acquired spectral data and compared to nutrient concentrations and changes in concentration levels in the water phase. Predictions of nutrient concentrations in the water column based on linear regressions between nutrient concentrations in the water column and the vegetation indices (PRI, NDVI, CI) yielded reasonable R2 values ranging from 0.26 to 0.52 for different indices. When the rates of change of PRI, NDVI and CI indices (Δ) between different sampling locations were compared to rates of change of nutrient levels in the wetland, the R2 values were also reasonable ranging from 0.51 to 0.64. These results suggest that combinations of the PRI, NDVI and CI index data may be a potentially useful predictor of nitrogen and phosphorous concentrations and uptake rate performance in constructed wetland water columns. The most optimal predictor of nutrient values appeared to be the NDVI index followed by the CI and PRI. Additionally, to demonstrate the potential applicability of this new approach for treatment wetland performance evaluation, a nitrogen dynamics model was developed using uptake rates determined from the field sample testing and radiometric measurements. However, long term data collection will still be necessary to more completely evaluate field scale channel constructed wetland performance removing nutrients through the different seasonal periods of operation. This work suggests that the use of hyperspectral reflectance technology in predicting the nutrient concentrations in a treatment constructed wetlands, and its scale up to field studies and modeling applications is a promising tool for design optimization and refinement

Pronóstico productivo de la avena forrajera de temporal por efecto del cambio climático en el noroeste de Chihuahua, México

Abstract Climate change can affect crop productivity in a particular region. The objective was to identify the variability in the production of dryland forage oat (Avena sativa L.) using a stochastic function and analyze their relationship with temperature and precipitation as affected by sceneries of climate change in the northwestern region of Chihuahua, Mexico. It was obtained 13 years of statistical information (2001-2013) at meteorological stations in the municipalities of Bachiniva and Namiquipa, using information on July, August and September months, where it is concentrated about 80% of annual precipitation. Information was taken from HADCM3 (2001) model that describes the behavior of climatic variables under pollutant emission scenarios A2 and B2 on the years 2050 and 2080. The changes in climate variables in the short term (2050) was taken and it is expected to increase both in temperature and precipitation, allowing in the case of Bachiniva improve the production of oats from 3.57 t/ha to 8.11 t/ha under pollutant emission scenario A2. In the long term (2080) a permanent increase in temperature is expected, and no matter how much precipitation improve, this will cause in the current oat producing regions fail to develop crops for harvest.Resumen El cambio climático puede afectar la productividad de los cultivos en una región determinada. El objetivo fue identificar la variabilidad en la producción de avena forrajera (Avena sativa L.) de temporal utilizando una función estocástica y analizar sus relaciones con la temperatura y precipitación, ante escenarios de cambio climático en la región noroeste de Chihuahua, México. Se obtuvo información estadística de 13 años (2001-2013) en las estaciones meteorológicas de los municipios de Bachíniva y Namiquipa utilizando la información de julio, agosto y septiembre, en cuyo periodo se concentra alrededor del 80% de la precipitación anual. Se tomó información del modelo HadCM3 (Modelo acoplado del Centro Hadley versión 3, 2001) que describe el comportamiento de variables climáticas bajo escenarios de emisión de contaminantes A2 y B2 para los años 2050 y 2080. Los cambios en las variables climáticas en el corto plazo (2050) se esperan con un aumento tanto en la temperatura como en la precipitación, lo que permite en el caso de Bachíniva mejorar la producción de avena de 3.57 t/ha a 8.11 t/ha bajo en escenario de emisión de contaminantes A2. A largo plazo (2080) se espera un incremento permanente en la temperatura y sin importar que tanto mejore la precipitación, esto provocara que en las actuales regiones productoras de avena no se logren desarrollar los cultivos para su cosecha

Total Organic Carbon Assessment in Soils Cultivated with Agave tequilana Weber in Jalisco, Mexico

The Agave tequilana Weber is an important commercial crop in the State of Jalisco, Mexico. However, the agave cultivation generates significant soil loss. For that reason, knowledge about the implementation of the agriculture management practices, such as manure application and the combination of inorganic fertilizers and manure, are relevant. The objective of this research was to determine the effect of agricultural management practices on the total organic carbon (TOC) in the soil in three study locations: Arandas, Tepatitlán, and Acatic in the Altos Sur region of Jalisco. A random sampling was carried out in each study location, 12 samples were obtained for each location at 0–30 cm deep, and a total of 36 samples were analyzed. The evaluated parameters were the potential hydrogen (pH), electrical conductivity (EC), bulk density (BD), soil-water saturation (SWS), total nitrogen (TN), and total organic carbon (TOC). Basic statistics and correlations between parameters were generated. In addition, to estimate TOC from a multivariate analysis, models were developed based on the lowest Akaike information criterion (AIC) and of the classification and regression trees (CART). ANOVA and Tukey test were determined. Results demonstrated a significant difference in the TOC percentages between the study locations. The Tukey test showed that there is no difference in TOC content between the Tepatitlán and Arandas sites, but there is a difference between these two sites and the Acatic. The latter resulted with the lowest values of TOC. Long-term studies are recommended to develop crop management strategies

Metales pesados en sedimentos de la Laguna de Bustillos, Chihuahua, México y comparación de agua regia y peróxido de hidrógeno como métodos de digestión

The aim was to quantify the level of pollution with metals in sediments of the Bustillos Lagoon and to compare two methods of digestion (agua regia and peroxide). Fifteen random points were selected, and samples were collected at the top (0-10 cm) and below (10-20 cm). The analysis was performed in a ICPOES quantifying chromium (Cr), iron (Fe), lithium (Li), magnesium (Mg), manganese (Mn), nickel (Ni), zinc (Zn), cobalt (Co), cooper (Cu), lead (Pb) and strontium (Sr). An ANOVA was carried out considering a 2x2 factorial arrangement. The results showed statistical differences for the digestion method (P<0.05), but no differences was noted for depth (P>0.05) neither for the interaction (P>0.05). It is concluded that the sediments of the Bustillos ecosystem do not represent a hazard because the metals Cr, Fe, Mn, Ni, Zn, Cu and Pb were not above the international and national standards and the metals Li, Mg, Co and Sr do not have standards.El objetivo fue conocer la contaminación por metales en sedimentos de la Laguna de Bustillos y comparar dos métodos de digestión (agua regia y peróxido). Se obtuvieron muestras en 15 puntos aleatorios de la superficie (0-10 cm) y de la parte inferior (10-20 cm). El análisis se realizó en un ICP-OES cuantificando cromo (Cr), fierro (Fe), litio (Li), magnesio (Mg), manganeso (Mn), níquel (Ni), zinc (Zn), cobalto (Co), cobre (Cu), plomo (Pb) y estroncio (Sr). Se efectuó un ANOVA bajo un arreglo factorial 2x2. Los resultados mostraron diferencias por el método de digestión (P0.05) o la interacción (P>0.05). La concentración de Cr, Fe, Mn, Ni, Zn, Cu y Pb no superó las normas nacionales o internacionales y para Li, Mg, Co y Sr no existen estándares. Se concluye que el sedimento se encuentra con niveles de metales que no representan un peligro para el ecosistema