The concentration of gases in the atmosphere is a topic of growing concern due to its effects on health, ecosystems etc. Its monitoring is commonly carried out through ground stations which offer high precision and temporal resolution. However, in countries with few stations, such as Ecuador, these data fail to adequately describe the spatial variability of pollutant concentrations. Remote sensing data have great potential to solve this complication. This study evaluates the spatiotemporal distribution of nitrogen dioxide (NO₂) and ozone (O₃) concentrations in Quito and Cuenca, using data obtained from ground-based and Sentinel-5 Precursor mission sources during the years 2019 and 2020. Moreover, a Linear Regression Model (LRM) was employed to analyze the correlation between ground-based and satellite datasets, revealing positive associations for O₃ (R² = 0.83, RMSE = 0.18) and NO₂ (R² = 0.83, RMSE = 0.25) in Quito; and O₃ (R² = 0.74, RMSE = 0.23) and NO₂, (R² = 0.73, RMSE = 0.23) for Cuenca. The agreement between ground-based and satellite datasets was analyzed by employing the intra-class correlation coefficient (ICC), reflecting good agreement between them (ICC ≥0.57); and using Bland and Altman coefficients, which showed low bias and that more than 95% of the differences are within the limits of agreement. Furthermore, the study investigated the impact of COVID-19 pandemic-related restrictions, such as social distancing and isolation, on atmospheric conditions. This was categorized into three periods for 2019 and 2020: before (from January 1st to March 15th), during (from March 16th to May 17th), and after (from March 18th to December 31st). A 51% decrease in NO₂ concentrations was recorded for Cuenca, while Quito experienced a 14.7% decrease. The tropospheric column decreased by 27.3% in Cuenca and 15.1% in Quito. O₃ showed an increasing trend, with tropospheric concentrations rising by 0.42% and 0.11% for Cuenca and Quito respectively, while the concentration in Cuenca decreased by 14.4%. Quito experienced an increase of 10.5%. Finally, the reduction of chemical species in the atmosphere as a consequence of mobility restrictions is highlighted. This study compared satellite and ground station data for NO₂ and O₃ concentrations. Despite differing units preventing data validation, it verified the Sentinel-5P satellite's effectiveness in anomaly detection. Our research's value lies in its applicability to developing countries, which may lack extensive monitoring networks, demonstrating the potential use of satellite technology in urban planning.

The leachate discharges generated in sanitary landfills contain many pollutants that are harmful to the environment; treatments are scarce and should be carried out better. The use of coagulation–flocculation processes has been one of the most widely used, but due to the complexity of the characterization of the leachate, the dosing strategy of coagulants and biopolymers needs to be clarified. Therefore, the present study was carried out to determine the doses of coagulants and biopolymers suitable for coagulation–flocculation processes in the treatment of leachates using computational models of machine learning techniques such as artificial neural networks (ANNs); these allow for decreasing the operations of the tests of jars in the laboratory, optimizing resources. Through laboratory experimentation, there are real results of the effectiveness of applying biopolymers in leachate treatments at different concentration levels. The laboratory results were taken as input variables for the algorithms used; after the validation and calibration process, we proceeded to estimate predicted data with the computational model, obtaining predictions of optimal doses for treatment with high statistical adjustment indicators. It is verified that the applied coagulation–flocculation treatments reduce the turbidity values in the leachate and contaminants associated with suspended solids. In this way, the jar tests are optimized so that the operational costs decrease without affecting the results of adequate dosing.

The typical vegetation cover of the Andes in southern Ecuador is composed of grassland wetland ecosystems. These form the basis of the area's hydrology, regulating water flows and supplying water to the lower regions of the basins. This study focuses on the Rircay River subbasin, where the dynamics of human activities have transformed natural ecosystems to alternative land uses, particularly cattle pastures. My study examines the change from native wet grasslands to introduced grasslands for livestock grazing. The research uses cartographic land use and land cover change data from 1990 to 2015. Subsequently, I evaluate the effect of these changes on river flow. Flow is measured at a control point at the exit of the total area. At this point, specific water quality parameters resulting from livestock contamination are measured and related using nonlinear models. The results are conclusive and indicate a marked decrease in river flows and an increase in the concentration of pollutants due to the increased area occupied by livestock pastures.

Nitrification is part of the nitrogen cycle that occurs naturally in ecosystems. It is related to the presence of microorganisms and their metabolism, especially bacteria, which are involved in oxidizing compounds such as NH₄⁺ and NO₂⁻ to NO₃⁻. In this study, we evaluated the nitrification potential in 12 bacteria strains that belong to the genera Aeromonas, Bacillus, Buttiauxella, Mycobacterium, Paenibacillus, Serratia, and Yersenia, which are part of the cultivable microbial community from soil in a native forest and pine forest in The Labrado area within the Machangara micro-watershed in the Andes located in the south of Ecuador. This investigation aims to identify heterotrophic and lithoautotrophic strains using specific culture media for ammonium oxidative (AOL-AOH) and nitrate oxidation bacteria (ONL-ONH). The formation of nitrifying halos in the culture media allowed the identification of 10 strains with nitrifying potential. Five strains were from the pine forest, four were isolated from the native forest, and one strain was shared between both forests. The Serratia and Yersinia genera have a high NO₂⁻ oxidation capacity. Their inoculation in synthetic water rich in nitrogenous products allowed us to determine 40% and 94% nitrite reduction percentages and cell retention times of 20 to 40 days. Our results are promising for their possible potential use in environmental bioremediation processes through inoculation in wastewater for the biological removal of nitrogenous compounds.

Ecosystem services contribute significantly to human development, with water production being a crucial component. Climate and land use changes can impact water availability within a basin. In this context, researching water-related areas is essential for formulating policies to protect and manage hydrological services. The objective of this study was to estimate water yield in the sub-basins of the Tabacay and Aguilán rivers under climate change scenarios in 2030, 2040, and 2050, combined with scenarios of changes in land cover and land use. The InVEST model was employed to analyze water yield. The results show that crop areas were identified as the lowest water yield in future scenarios, and forested areas, particularly the region where the Cubilán Protected Forest is located, contribute the most to water yield in the subbasin. Besides, water yield has increased in the historic period (2016–2018) due to the conservation and reforestation initiatives carried out by the Municipal Public Service Company for Drinking Water, Sewerage, and Environmental Sanitation of the city of Azogues in 2018, the so-called Reciprocal Agreements for Water. Additionally, an increase in water yield is projected for future scenarios. This study can serve as a basis for decision-makers to identify areas that should prioritize protection and conservation.

La morfometría de las cuencas hidrográficas de la vertiente del Pacífico en el territorio ecuatoriano es analizada con información topográfica digitalizada en un Modelo de Elevaciones obteniendo características de superficie, relieve y red hídrica, que determinan el comportamiento hidrológico. El análisis se realiza a 13 cuencas hidrográficas que representan un área de 92,775.87 km2; los resultados son obtenidos mediante un análisis estadístico de las relaciones que forman las características morfométricas, obteniendo una caracterización hidrológica de una zona de gran influencia de la vertiente del Pacífico. Los parámetros utilizados son factor de Horton, coeficiente de compacidad, densidad de drenaje, rugosidad de la cuenca, relación de bifurcación y relación de elongación. Para cada uno de los parámetros analizados se calcularon estadísticos de posición y de dispersión, además de pruebas estadísticas y análisis de agrupamiento, evaluando las relaciones que existen entre cada uno de los sistemas, obteniendo similitudes morfométricas y formando grupos