Search

The final publication is available at Springer via http://dx.doi.org/10.1007/s10661-021-09063-5, The eco-efficiency evaluation in wastewater treatment plants (WWTPs) is used to know and improve the environmental and economic efficiency of these processes, systems, products, and services. The eco-efficiency evaluations in WWTP contemplate the inputs to be minimized, the desirable results to be maximized, and the undesired results to be minimized. Data envelopment analysis (DEA) is a widely used method to evaluate the eco-efficiency of WWTPs; integrating several approaches in a single index, traditional DEA models do not take into account the uncertainty in the data. This study evaluates the eco-efficiency of a sample of Catalan WWTPs, considering the uncertainty of the data (DEA tolerance model), and it is for the first time that together with CO2, other greenhouse gas (GHG) such as CH4 and N2O are considered as part of the process outputs. GHG emissions were quantified using methods reported in the literature. Seven hundred twenty-nine eco-efficiency scores were estimated for each WWTP instead of a single score like conventional DEA models, analyzing optimistic and pessimistic scenarios. The WWTPs were classified according to the estimated eco-efficiency scores, accounting for the uncertainty in each of the scenarios, and demonstrating the changes in the performance of the WWTPs in the different scenarios. Only two WWTPs were eco-efficient in all the scenarios evaluated. This approach provides essential information to improve efficiency and innovation in the wastewater sector., Monserrat Ramírez-Melgarejo received a scholarship from CONACYT with agreement number 612685., Peer Reviewed, Objectius de Desenvolupament Sostenible::6 - Aigua Neta i Sanejament::6.3 - Per a 2030, millorar la qualitat de l’aigua mitjançant la reducció de la contaminació, l’eliminació dels abocaments i la reducció al mínim de la descàrrega de materials i productes químics perillosos, la reducció a la meitat del percentatge d’aigües residuals sense tractar, i un augment substancial a escala mundial del reciclat i de la reutilització en condicions de seguretat, Objectius de Desenvolupament Sostenible::11 - Ciutats i Comunitats Sostenibles, Objectius de Desenvolupament Sostenible::11 - Ciutats i Comunitats Sostenibles::11.6 - Per a 2030, reduir l’impacte ambiental negatiu per capita de les ciutats, amb especial atenció a la qualitat de l’aire, així com a la gestió dels residus municipals i d’altre tipus, Objectius de Desenvolupament Sostenible::6 - Aigua Neta i Sanejament, Objectius de Desenvolupament Sostenible::13 - Acció per al Clima::13.2 - Incorporar mesures relatives al canvi climàtic en les polítiques, les estratègies i els plans nacionals, Objectius de Desenvolupament Sostenible::13 - Acció per al Clima, Postprint (author's final draft)

In this study we determined the magnitude of plant mediated CH4 emission (flux) in two vegetation types of Carex ramenskii. The objectives of this paper were to quantify the proportion of CH4 emissions from plant mediated flux and the total flux (plant and soil). This information is needed in order to understand how grazing affects plant mediated CH4 flux. In addition, we differentiated between two vegetation morphs, grazed and ungrazed, and determined the plant mediated CH4 flux for vegetation type. This study was conducted at a field site on the Tutakoke River (61 15’N, 165 30’W) which is located in the coastal region of the Yukon-Kuskokwim Delta. Three replicate plots of the two vegetation morphs of Carex ramenskii were established. Methane flux was measured with a total flux chamber (plant and soil) and a single leaf chamber using a Picarro Cavity Ring-Down Spectroscopy Analyzer (Model G2308, Picarro Inc., Santa Clara, California). Plant density for the two plant types was determined. Temperature measurements were taken and correlated with gas flux. This study found that total net CH4 emissions from Carex ssp. were the same in both vegetation types. This similarity could indicate that plant mediated flux through vegetation is not affected by grazing in the sense that grazing is neither facilitating nor inhibiting plant mediated CH4 flux. The magnitude of plant mediated flux was still greater in the ungrazed meadow type, indicating on both greater facilitation of CH4 flux, and below ground oxygen transport enabling higher rates of CH4 consumption.

Conservation tillage and crop rotations improve soil quality. However, the impact of these practices on greenhouse gas (GHG) emissions and crop yields is not well defined, particularly in dry climates. A rainfed 2-year field-experiment was conducted to evaluate the effect of three long-term (17–18 years) tillage systems (Conventional Tillage (CT), Minimum Tillage (MT) and No Tillage (NT)) and two cropping systems (rotational wheat (Triticum aestivum L.) preceded by fallow, and wheat in monoculture), on nitrous oxide (N2O) and methane (CH4) emissions, during two field campaigns. Soil mineral N, water-filled pore space, dissolved organic carbon (C) and grain yield were measured and yield-scaled N2O emissions, N surplus and Global Warming Potentials (GWP) were calculated. No tillage only decreased cumulative N2O losses (compared to MT/CT) during campaign 1 (the driest campaign with least fertilizer N input), while tillage did not affect CH4 oxidation. The GWP demonstrated that the enhancement of C stocks under NT caused this tillage management to decrease overall CO2 equivalent emissions. Monoculture increased N2O fluxes during campaign 2 (normal year and conventional N input) and decreased CH4 uptake, as opposed to rotational wheat. Conversely, wheat in monoculture tended to increase soil organic C stocks and therefore resulted in a lower GWP, but differences were not statistically significant. Grain yields were strongly influenced by climatic variability. The NT and CT treatments yielded most during the dry and the normal campaign, and the yield-scaled N2O emissions followed the same tendency. Minimum tillage was not an adequate tillage management considering the GWP and the yield-scaled N2O emissions (which were 39% lower in NT with respect to MT). Regarding the crop effect, wheat in rotation resulted in a 32% increase in grain yield and 31% mitigation of yield-scaled N2O emissions. Low cumulative N2O fluxes (<250 g N2O-N ha−1 campaign−1) highlighted the relevanc

In this study we determined the magnitude of plant mediated CH4 emission (flux) in two vegetation types of Carex ramenskii. The objectives of this paper were to quantify the proportion of CH4 emissions from plant mediated flux and the total flux (plant and soil). This information is needed in order to understand how grazing affects plant mediated CH4 flux. In addition, we differentiated between two vegetation morphs, grazed and ungrazed, and determined the plant mediated CH4 flux for vegetation type. This study was conducted at a field site on the Tutakoke River (61 15’N, 165 30’W) which is located in the coastal region of the Yukon-Kuskokwim Delta. Three replicate plots of the two vegetation morphs of Carex ramenskii were established. Methane flux was measured with a total flux chamber (plant and soil) and a single leaf chamber using a Picarro Cavity Ring-Down Spectroscopy Analyzer (Model G2308, Picarro Inc., Santa Clara, California). Plant density for the two plant types was determined. Temperature measurements were taken and correlated with gas flux. This study found that total net CH4 emissions from Carex ssp. were the same in both vegetation types. This similarity could indicate that plant mediated flux through vegetation is not affected by grazing in the sense that grazing is neither facilitating nor inhibiting plant mediated CH4 flux. The magnitude of plant mediated flux was still greater in the ungrazed meadow type, indicating on both greater facilitation of CH4 flux, and below ground oxygen transport enabling higher rates of CH4 consumption.