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High nutrient discharge from groundwater (GW) into surface water (SW) have multiple undesirable effects on river water quality. With the aim to estimate the impact of anthropic pressures and river–aquifer interactions on nitrate status in SW, this study integrates two hydrological simulation and water quality models. PATRICAL models SW–GW interactions and RREA models streamflow changes due to human activity. The models were applied to the Júcar River Basin District (RBD), where 33% of the aquifers have a concentration above 50 mg NO3−/L. As a result, there is a direct linear correlation between the nitrate concentration in rivers and aquifers (Júcar r2 = 0.9, and Turia r2 = 0.8), since in these Mediterranean basins, the main amount of river flows comes from groundwater discharge. The concentration of nitrates in rivers and GW tends to increase downstream of the district, where artificial surfaces and agriculture are concentrated. The total NO3− load to Júcar RBD rivers was estimated at 10,202 tN/year (239 kg/km2/year), from which 99% is generated by diffuse pollution, and 3378 tN/year (79 kg/km2/year) is discharged into the Mediterranean Sea. Changes in nitrate concentration in the RBD rivers are strongly related to the source of irrigation water, river–aquifer interactions, and flow regulation. The models used in this paper allow the identification of pollution sources, the forecasting of nitrate concentration in surface and groundwater, and the evaluation of the efficiency of measures to prevent water degradation, among other applications.

Este trabajo presenta los resultados del estudio de caso del transporte informal de las comunas 15 y 18 de la ciudad de Cali. El transporte informal ha sido trabajado como una de las constantes en las ciudades latinoamericanas. En la literatura, este fenómeno se relaciona como un efecto de la implementacion de las políticas neoliberales de privatizacion de los sistemas de transporte o como una evidencia de la incapacidad de la Administracion pública y del Estado para hacerse cargo de su espacio de soberania. Este trabajo problematiza estos diagnósticos y sugiere una nueva manera de abordar el transporte informal en las urbes del sur global. Con técnicas etnográficas, el trabajo muestra como la informalidad es un espacio socialmente construido con tres caracteristicas principales: a) la persistencia de hombres prestadores del servicio y mujeres usuarias, ambos de bajos ingresos económicos, solidarios entre si para resistir ante un sistema oficial que los excluye; b) el uso significativo de esta clase de transportes de mujeres de estratos bajos que necesitan movilizarse, de manera flexible y económica, de zonas alejadas de los centros productivos, excluidos de los diseños de rutas de transporte, y c) la burocratización de las prácticas asociadas con la prestación del servicio informal. Estos hallazgos permiten sostener que los espacios urbanos son construcciones sociales que, al estar cruzadas por vectores de poder como el género, hacen que la experiencia geográfica de hombres y mujeres sea diferenciada.

AbstractFly ash is currently a problem in different companies, mainly in thermoelectric plants, which must follow a production and consumption model that involves reusing, renewing, and recycling, thus contributing to the circular economy. This work aims to evaluate the reactivity and compressive strength of different types of ashes in concrete monoliths. For this purpose, sugarcane bagasse (SCBA), bituminous coal (BC), and untreated hazardous waste (RUD) were evaluated as replacements for cement. Monoliths and mortars have been manufactured in different mixtures, taken to a curing room, and their compressive strength and reactivity have been determined at different times (up to 28 days for the monoliths and up to 90 for the mortars), mainly in order to check the formation of calcium silicate hydrate (CSH) gels. In the monolith tests, the best performances have been with SCBA and BC, which have been used for the manufacture of the mortars. On day 56, the behavior of the replacement of 30% fly ash (15% BC:15% SCBA) presents a type H mortar behavior, with better results than the control. By day 90, all replacements had the same resistance as M mortars and even higher resistances than the control. This demonstrates the feasibility of its use in the production of Portland cement for the manufacture of low‐performance inputs. This implies the possible reduction of impacts, both in waste disposal sites and in emissions caused by the construction industry, thus contributing to the circular economy.

This research aims to show the positive and negative indirect effects of COVID-19 on the environment, particularly in the most affected countries such as China, USA, Italy, and Spain. Our research shows that there is a significant association between contingency measures and improvement in air quality, clean beaches and environmental noise reduction. On the other hand, there are also negative secondary aspects such as the reduction in recycling and the increase in waste, further endangering the contamination of physical spaces (water and land), in addition to air. Global economic activity is expected to return in the coming months in most countries (even if slowly), so decreasing GHG concentrations during a short period is not a sustainable way to clean up our environment.

We propose a methodology to price an insurance contract designed to hedge the volumetric risk associated with weather conditions. Our methodology is based on conditional quantile regressions and adapts Value at Risk (VaR) and Expected Shortfall statistics from the literature on financial econometrics. In our empirical application, we use actual daily meteorological and radiation data for 40 European cities in 13 countries, from April 1, 2011, to December 31, 2021, and calculate the value of the annual insurance premium under reasonable assumptions on the technology of the solar panels and expected energy demand. We consider variables such as temperature, wind speed, and precipitation in our calculations. Our results for the different cities in our sample show that due to the nonlinear impact of weather (mainly temperature and precipitation) on the expected generation losses, it is appropriate to use quantile regressions to calculate the VaR of radiation, conditional on weather factors. Our insurance premium calculations also present a high degree of variation across European, which indicates that risk-diversification opportunities of catastrophic risk due to weather conditions faced by insurance companies exist. This variation is explained by different weather conditions, model adjustment, and the average price of electricity.

Satisfying energy demand has become a global problem that is on the rise due to population growth, infrastructure deterioration, a decline in fossil fuel sources, and high costs for investment, among others. Smart grids, in addition to those challenges that they have at the level of energy generation, have other management challenges derived from the great diversity of components that make them up, such as energy storage systems (batteries, capacitors, etc.), the different types of consumers (controllable, non-controllable loads) and prosumers (electric vehicles, self-sustaining buildings, micro-grid, etc.), among others. Consequently, a distributed control problem is presented, mainly oriented to the coordination of its components. A possible solution is to achieve the participation of each component when conditions are more favorable, such as prioritizing production with renewable energy sources, or taking advantage of prosumers so that they can meet local demand, among other things. Therefore, new strategies with a distributed approach such as bio-inspired emergent controls are necessary. The objective of this work is the specification of an emergent control approach to coordinate a smart grid. This approach allows the coordination of the energy supply in various operating scenarios. The results obtained demonstrate a perfect synchronization between the different smart grid components (agents), prioritizing renewable energy sources, regardless of the operational context (for example, in cases of failures, unsuitable environmental conditions, etc.). TRUE pub

Wavelet power spectrum (WPS) and wavelet coherence analyses (WCA) are used to examine the co-movements among oil prices, green bonds, and CO2 emissions on daily data from January 2014 to October 2022. The WPS results show that oil returns exhibit significant volatility at low and medium frequencies, particularly in 2014, 2019–2020, and 2022. Also, the Green Bond Index presents significant volatility at the end of 2019–2020 and the beginning of 2022 at low, medium, and high frequencies. Additionally, CO2 futures’ returns present high volatility at low and medium frequencies, expressly in 2015–2016, 2018, the end of 2019–2020, and 2022. WCA’s empirical findings reveal (i) that oil returns have a negative impact on the Green Bond Index in the medium term. (ii) There is a strong interdependence between oil prices and CO2 futures’ returns, in short, medium, and long terms, as inferred from the time–frequency analysis. (iii) There also is evidence of strong short, medium, and long terms co-movements between the Green Bond Index and CO2 futures’ returns, with the Green Bond Index leading.