Production of zeolitic materials in pilot scale based on coal ash for phosphate and potassium adsorption in order to obtain fertilizer

Environmental Science and Pollution Research - The use of different types of zeolites (X, Na-P1, and 4A) synthesized by different methods and scales were tested in this work to adsorb nutrients...     

A simple spectroscopic method to determine dimethoate in water samples by complex formation

Abstract

A simple and rapid method for the determination of dimethoate in water was developed based on the monitoring of the complex formation between bis 5-phenyldipyrrinate of nickel (II) and the herbicide dimethoate. The method showed a short response time (10?s), high selectivity (very low interference from other sulfate and salts), high sensitivity (limit of detection (LOD) 0.45?µM, limit of quantitation (LOQ) of 1.39?µM), and a K_d of 2.4?µM. Stoichiometry experiments showed that complex formation occurred with a 1:1 relation. The method was applied to different environmental water samples such as lagoon, stream, urban, and groundwater samples. The results indicated that independently from the water source, the method exhibited high precision (0.25–2.47% variation coefficient) and accuracy (84.42–115.68% recovery). In addition, the method was also tested using an effluent from a wastewater treatment plant from Mexico; however, the results indicated that the presence of organic matter had a pronounced effect on the detection.     

Threshold responses of Amazonian stream fishes to timing and extent of deforestation

Deforestation is a primary driver of biodiversity change through habitat loss and fragmentation. Stream biodiversity may not respond to deforestation in a simple linear relationship. Rather, threshold responses to extent and timing of deforestation may occur. Identification of critical deforestation thresholds is needed for effective conservation and management. We tested for threshold responses of fish species and functional groups to degree of watershed and riparian zone deforestation and time since impact in 75 streams in the western Brazilian Amazon. We used remote sensing to assess deforestation from 1984 to 2011. Fish assemblages were sampled with seines and dip nets in a standardized manner. Fish species (n = 84) were classified into 20 functional groups based on ecomorphological traits associated with habitat use, feeding, and locomotion. Threshold responses were quantified using threshold indicator taxa analysis. Negative threshold responses to deforestation were common and consistently occurred at very low levels of deforestation (<20%) and soon after impact (<10 years). Sensitive species were functionally unique and associated with complex habitats and structures of allochthonous origin found in forested watersheds. Positive threshold responses of species were less common and generally occurred at >70% deforestation and >10 years after impact. Findings were similar at the community level for both taxonomic and functional analyses. Because most negative threshold responses occurred at low levels of deforestation and soon after impact, even minimal change is expected to negatively affect biodiversity. Delayed positive threshold responses to extreme deforestation by a few species do not offset the loss of sensitive taxa and likely contribute to biotic homogenization.     

Ammonia and methane oxidation on TiO2 supported on glass fiber mesh under artificial solar irradiation

Environmental Science and Pollution Research - In this work, we present the application of solar photocatalysis for air purification including toxic substances such as ammonia and methane normally...     

Comparison of modeling with empirical calculation of diffuse and fugitive methane emissions in a Spanish landfill

One of the most significant environmental problems arising from landfills is the emission of methane into the atmosphere. In this study, methane emissions from a currently in-use Spanish landfill were modeled as well as being experimentally measured using a two-step method. The first step involved a qualitative walkover survey to detect where gases were being emitted on the surface of the landfill. The second stage comprised a quantitative analysis of these surface methane emissions at a selected number of points on the landfill surface using a specially designed flux chamber. The statistical analysis of the data obtained was based on the Sichel function and resulted in an average emission rate of 74.9 g·m^?2·day^?1, with 27.8 and 202.1 g·m^?2·day^?1 as the lower and upper limits of the 95% confidence interval, respectively. The total emission for the landfill, with an emitting surface of 335,000 m², is 9.16 × 10³ ton/yr. These values have been compared with those from three different models, with the model results being above the calculated mean emissions measured at the landfill, but below the upper confidence limit at 95%.

Implications: One of the main environmental problems arising from the presence of landfills is the emission of biogas (which mainly contains methane and carbon dioxide) into the atmosphere. Several experimental methods as well as models have been developed to quantify these emissions. In this work, the authors have compared the results obtained using experimental measurements with those provided by some local and international models using the default parameters proposed. The results obtained from the experimental method are in accordance with those provided by the models, although the models could be slightly overestimating these emissions.     

Socioecological transition in the Cauca river valley,Colombia (1943–2010): towards an energy–landscape integrated analysis

Regional Environmental Change - Agroecosystems are facing a global challenge amidst a socioecological transition that places them in a dilemma between increasing land-use intensity to meet the...