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1.
J Environ Manage ; 301: 113934, 2022 Jan 01.
Artículo en Inglés | MEDLINE | ID: mdl-34731952

RESUMEN

As China urbanized and its economy grew rapidly, its food production and consumption patterns changed dramatically over the past three decades. With this in mind, we evaluate how the nation's greenhouse gas (GHG) emissions related to food production and consumption altered from 1987 to 2017. We further explore key factors that affect GHG emission changes from agricultural production and household diet perspectives. We find that the GHG emissions from China's food production rose 51 percent, while that from food consumption rose 64 percent. The rise in GHG footprint of China's food production was largely caused by the increasing material- and energy-intensive food production system. Agricultural modernization was a main cause of the rise in GHGs, as China was late to the game in improving agricultural productivity. But a more meat-intensive diet accompanied by a general rise in households' use of processed food also helped to drive these transformations. China's growing appetite for meat not only intensified GHG mitigation pressures domestically, but also abroad, as Chinese households began to demand greater variety that was satisfied via imports. Indeed, GHG emissions embodied in imported meats rose over eleven-fold from 2007 to 2017. Through this study, we highlight the importance of future policy-making focused on a more sustainable food system in China to benefit the world's environment, health, and climate.


Asunto(s)
Gases de Efecto Invernadero , Agricultura , China , Efecto Invernadero , Gases de Efecto Invernadero/análisis , Carne
2.
Waste Manag ; 136: 321-336, 2021 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-34752972

RESUMEN

Growing municipal solid waste (MSW) generation is a source of environmental, economic, and social concerns, especially in developing world megacities where poor MSW practices prevail. Mexico City (CDMX), one of the world's largest megacities, daily produces âˆ¼ 13,073 Mg of MSW whose management poses a tremendous challenge to local authorities and calls for additional research to conceive sound MSW strategies. This study evaluates the fossil energy use, GHG emissions, resource recovery, and economic cost dimensions of current and five alternative MSW paths in CDMX to compare their performance and identify more sustainable MSW practices for the megacity. Impacts and benefits from the MSW paths were modeled using 2018 MSW generation data, information supplied by local authorities, and literature values. Current MSW path consumes âˆ¼ 387 MJfossil, generates âˆ¼ 501 kg-CO2e, and costs âˆ¼ 57 USD2018 per Mg of MSW managed while it only valorizes < 33% of total MSW mostly via informal truck-picking. The alternative MSW paths considerably reduce GHG emissions (∼129-360 kg-CO2e/Mg) and enhance MSW valorization (∼47-88%) though, they entail higher fossil energy consumption (447-582 MJfossil/Mg) and, in general, higher cost expenditures (43-208 USD2018/Mg). Heavy reliance on landfilling, large GHG emissions, and low MSW valorization make current MSW path in CDMX unsustainable. Incineration-based MSW paths perform better in most aspects evaluated but their high costs seem prohibitive. Results suggest MSW paths featuring open windrow composting, mechanical-biological pre-treatment, material recovery facilities, and refuse-derived fuel production may be more appropriate to improve the sustainability of CDMX MSW management.


Asunto(s)
Eliminación de Residuos , Administración de Residuos , Ciudades , Efecto Invernadero , México , Residuos Sólidos/análisis
4.
Artículo en Inglés | MEDLINE | ID: mdl-34682714

RESUMEN

The construction industry has a considerable environmental impact in societies, which must be controlled to achieve adequate sustainability levels. In particular, cement production contributes 5-8% of CO2 emissions worldwide, mainly from the utilization of clinker. This study applied Life Cycle Assessment (LCA) methodology to investigate the environmental impact of cement production and explore environmental improvements obtained by adding marble waste sludges in the manufacture of Portland cement. It was considered that 6-35% of the limestone required for its production could be supplied by marble waste sludge (mainly calcite), meeting the EN 197-1:2011 norm. Energy consumption and greenhouse gas (GHG) emission data were obtained from the Ecovent database using commercial LCA software. All life cycle impact assessment indicators were lower for the proposed "eco-cement" than for conventional cement, attributable to changes in the utilization of limestone and clinker. The most favorable results were achieved when marble waste sludge completely replaced limestone and was added to clinker at 35%. In comparison to conventional Portland cement production, this process reduced GHG emissions by 34%, the use of turbine waters by 60%, and the emission of particles into the atmosphere by 50%. Application of LCA methodology allowed evaluation of the environmental impact and improvements obtained with the production of a type of functional eco-cement. This approach is indispensable for evaluating the environmental benefits of using marble waste sludges in the production of cement.


Asunto(s)
Gases de Efecto Invernadero , Aguas del Alcantarillado , Animales , Carbonato de Calcio , Materiales de Construcción , Efecto Invernadero , Estadios del Ciclo de Vida
5.
Environ Sci Technol ; 55(21): 14806-14816, 2021 11 02.
Artículo en Inglés | MEDLINE | ID: mdl-34652143

RESUMEN

This study presents a cradle-to-grave life cycle analysis (LCA) of the greenhouse gas (GHG) emissions of the electricity generated from forest biomass in different regions of the United States (U.S.), taking into consideration regional variations in biomass availabilities and logistics. The regional biomass supply for a 20 MW bioelectricity facility is estimated using the Land Use and Resource Allocation (LURA) model. Results from LURA and data on regional forest management, harvesting, and processing are incorporated into the GHGs, Regulated Emissions, and Energy Use in Technologies (GREET) model for LCA. The results suggest that GHG emissions of mill residues-based pathways can be 15-52% lower than those of pulpwood-based pathways, with logging residues falling in between. Nonetheless, our analysis suggests that screening bioenergy projects on specific feedstock types alone is not sufficient because GHG emissions of a pulpwood-based pathway in one state can be lower than those of a mill residue-based pathway in another state. Furthermore, the available biomass supply often consists of several woody feedstocks, and its composition is region-dependent. Forest biomass-derived electricity is associated with 86-93% lower life-cycle GHG emissions than the emissions of the average grid electricity in the U.S. Key factors driving bioelectricity GHG emissions include electricity generation efficiency, transportation distance, and energy use for biomass harvesting and processing.


Asunto(s)
Contaminantes Atmosféricos , Gases de Efecto Invernadero , Contaminantes Atmosféricos/análisis , Animales , Biomasa , Electricidad , Bosques , Efecto Invernadero , Estadios del Ciclo de Vida , Estados Unidos
6.
Artículo en Inglés | MEDLINE | ID: mdl-34639670

RESUMEN

Oxygen production in cryogenic air separation units is related to a significant carbon footprint and its supply in the medicinal sphere became critical during the recent COVID-19 crisis. An improved unit design was proposed, utilizing a part of waste heat produced during air pre-cooling and intercooling via absorption coolers, to reduce power consumption. Variable ambient air humidity impact on compressed air dryers' regeneration was also considered. A steady-state process simulation of a model 500 t h-1 inlet cryogenic air separation unit was performed in Aspen Plus® V11. Comparison of a model without and with absorption coolers yielded an achievable reduction in power consumption for air compression and air dryer regeneration by 6 to 9% (23 to 33 GWh year-1) and a favorable simple payback period of 4 to 10 years, both depending on air pressure loss in additional heat exchangers to be installed. The resulting specific oxygen production decrease amounted to EUR 2-4.2 t-1. Emissions of major gaseous pollutants from power production were both calculated by an in-house developed thermal power plant model and adopted from literature. A power consumption cut was translated into the following annual greenhouse gas emission reduction: CO2 16 to 30 kilotons, CO 0.3 to 2.3 tons, SOx 4.7 to 187 tons and NOx 11 to 56 tons, depending on applied fossil fuel-based emission factors. Considering a more renewable energy sources-containing energy mix, annual greenhouse gas emissions decreased by 50 to over 80%, varying for individual pollutants.


Asunto(s)
Contaminantes Atmosféricos , Contaminación del Aire , COVID-19 , Gases de Efecto Invernadero , Contaminantes Atmosféricos/análisis , Contaminación del Aire/análisis , Efecto Invernadero , Calor , Humanos , Oxígeno , SARS-CoV-2
7.
J Environ Manage ; 300: 113836, 2021 Dec 15.
Artículo en Inglés | MEDLINE | ID: mdl-34649322

RESUMEN

Trade has been substantially influencing regional economic development, environmental sustainability, and human well-being. Enabled by the decomposition analysis, pollution haven hypothesis or "no-trade" scenarios (NTSs), the effects of trade on global/national social-economic-environmental development have been revealed. However, major limitations (e.g., using with-trade economic structures or neglecting price differences) existed in previous studies, and thus made the previous assessments of trade's effects unsatisfactorily. This study develops a novel NTS that addresses the existing limitations, and further applies it to estimate the effect of trade on global economic development and greenhouse gas (GHG) emissions. We show that current international trade benefits the global economic growth but with a consequence of more GHG emissions compared with the NTS. The hypothetical production in small countries (e.g., Luxembourg or Japan) would be more constrained by the production factors (e.g., land) under the NTS, compared with those factor-endowment countries (e.g., the United States or India). For country-specific analysis, we find that today's developed countries would have a substantial increase in their GHG emissions of clothing- and service-related products under the NTS, whereas countries with net-export (e.g., China or Brazil) would have less GHG emissions under the NTS. Enhancing future global collaborations is vital, especially for small or resource-deficient economies, if they are to achieve the Sustainable Development Goals.


Asunto(s)
Gases de Efecto Invernadero , Dióxido de Carbono/análisis , Comercio , Desarrollo Económico , Efecto Invernadero , Humanos , Internacionalidad
8.
Rev Sci Tech ; 40(2): 431-438, 2021 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-34542104

RESUMEN

Climate change due to increasing greenhouse gas (GHG) emissions is one of the most pressing issues facing society on a global scale. The growth of GHG emissions between 2000 and 2010 was higher than in each of the previous three decades, and each of the past four decades has been successively warmer than any preceding decades since 1850. Continued GHG emissions will cause further warming and changes in the climate system. Climate change affects livestock production in multiple ways, both directly and indirectly. Many of the impacts on the livestock sector result from increasing frequency and magnitude of weather and climate extremes such as droughts, flash floods, untimely rains, frost, hail and severe storms. This article describes some of the most vulnerable disaster communities in Asia, Africa, Australia, Europe and South America. It then describes the importance of meteorological information provided by national Meteorological and Hydrological Services to help Veterinary Services support sustainable management of livestock in vulnerable pastoral communities.


Asunto(s)
Desastres , Gases de Efecto Invernadero , Animales , Cambio Climático , Sequías , Efecto Invernadero , Ganado
9.
Rev Sci Tech ; 40(2): 421-430, 2021 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-34542106

RESUMEN

Climate change due to increasing greenhouse gas (GHG) emissions is one of the most pressing issues facing society on a global scale. The growth of GHG emissions between 2000 and 2010 was higher than in each of the previous three decades, and each of the past four decades has been successively warmer than any preceding decades since 1850. Continued GHG emissions will cause further warming and changes in the climate system. Climate change affects livestock production in multiple ways, both directly and indirectly. Many of the impacts on the livestock sector result from increasing frequency and magnitude of weather and climate extremes such as droughts, flash floods, untimely rains, frost, hail and severe storms. This article describes some of the most vulnerable disaster communities in Asia, Africa, Australia, Europe and South America. It then describes the importance of meteorological information provided by national Meteorological and Hydrological Services to help Veterinary Services support sustainable management of livestock in vulnerable pastoral communities.


Asunto(s)
Desastres , Gases de Efecto Invernadero , Animales , Cambio Climático , Sequías , Efecto Invernadero , Ganado
10.
J Environ Manage ; 300: 113746, 2021 Dec 15.
Artículo en Inglés | MEDLINE | ID: mdl-34562822

RESUMEN

Greenhouse gas emissions from power plants that use fossil fuels cause a serious impact to the environment, for this reason the use of renewable energy technologies is an important alternative as a way of combatting climate change. The production of power via biomass is considered as a carbon neutral energy resource, but it is well known that the non-fossil CO2 emitted from this type of processes can also be captured. In order to do so, in this work it is proposed a match between a Biogas combined cycle power plant and postcombustion carbon capture process, to capture the CO2 produced by the biogas combustion, and also it considered a match with an organic Rankine cycle that uses the wasted energy of the combustion gases. Additionally, it is considered that the captured carbon is used to produce some value-added chemicals and fuels. Environmental and energetic evaluations were carried out for the coupling of those technologies. The implementation of the carbon capture plant, results on a diminution of the 87% of the emission of the combined cycle power plant. The life cycle analysis results show that the study case of Syngas production via dry reforming of methane, presents the lower global warming potential (0.088 CO2-eq kg/kg) and it was also found that the global warming potential has a reduction with the help of the mass integration between the different alternatives of CO2 utilization. Finally, it was found an annual reduction of 0.055 CO2-eq t for the system with mass integration compared with the cases without mass integration.


Asunto(s)
Biocombustibles , Dióxido de Carbono , Carbono , Dióxido de Carbono/análisis , Efecto Invernadero , Centrales Eléctricas
11.
J Environ Manage ; 300: 113698, 2021 Dec 15.
Artículo en Inglés | MEDLINE | ID: mdl-34530365

RESUMEN

This study aimed to quantify greenhouse gas emissions derived from the production-consumption of rice in Hubei-a major rice-producing province in central China. This research employed primary and secondary data collection methods. Primary data sources included interviews and experimental observations from seven counties in Hubei collected from June 2016 to December 2016. Secondary data sources-including national datasets, inter-governmental reports, and peer-reviewed articles-were used to extract relevant data, such as emission factors, and national and provincial rice output. Life Cycle Assessment was employed to build a comprehensive inventory and map of the rice carbon footprint, including the following five stages: production inputs, farm management, growth period, processing and sale, and consumption. Uncertainty analysis was performed to validate the reliability of carbon footprint estimations. Results showed that the carbon footprint for every 1 ton of polished rice in Hubei ranged between 4.19-6.81 t CO2e/t and was 5.39 t CO2e/t on average. Greenhouse gas emissions were primarily produced from rice fields during the growth stage (over 60% of greenhouse gas emissions of the whole life cycle of rice), followed by the consumption stage, and the production and transportation of agricultural inputs. Uncertainty analysis estimations indicated acceptable levels of reliability. This study's results indicate that the production and consumption of rice is a significant contributor to agricultural carbon emissions in Hubei-consistent with national estimates that place China as the largest carbon dioxide emitter globally. This research provides further insight into future policies and targeted initiatives for the efficient use of low-carbon agricultural inputs for rice production and consumption stages in China.


Asunto(s)
Agricultura , Huella de Carbono , Oryza , China , Efecto Invernadero , Oryza/crecimiento & desarrollo , Reproducibilidad de los Resultados , Incertidumbre
12.
Environ Sci Pollut Res Int ; 28(44): 61929-61950, 2021 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-34553283

RESUMEN

Energy is a key attribute that is used to evaluate the economic development of any country. The demand for energy is going to rise in developing countries and will be 67% of global use by 2040. The energy surge in these rising economies will be responsible for 60-70% of the global greenhouse gas emissions. The quest for higher energy motivates technological development to curb the climate change occurring with GHG emissions. Carbon dioxide is one of the primary greenhouse gases in the atmosphere. Current work is intended to give an updated review on the different routes of carbon dioxide utilization that are catalytic route, photocatalytic route, electrocatalytic route, microwave plasma route, and biocatalytic route. These routes are capable of converting CO2 into different valuable products such as formic acid, methanol, and di-methyl ether (DME), which are majorly derived from biomass and/or fossil fuels (coal gasification and/or natural gas). This work investigates the effect of different routes available for the production of value-added products by CO2 reduction, discusses various challenges that come across the aforementioned routes, and shares views on future scope and research direction to pave new innovative ways of reducing CO2 from the environment.


Asunto(s)
Dióxido de Carbono , Gases de Efecto Invernadero , Dióxido de Carbono/análisis , Cambio Climático , Carbón Mineral , Combustibles Fósiles , Efecto Invernadero
13.
Am J Clin Nutr ; 114(5): 1686-1697, 2021 11 08.
Artículo en Inglés | MEDLINE | ID: mdl-34477830

RESUMEN

BACKGROUND: To guide the transformation of food systems to provide for healthy and sustainable diets, countries need to assess their current diet and food supply in comparison to nutrition, health, affordability, and environmental goals. OBJECTIVES: We sought to compare Indonesia's food utilization to diets optimized for nutritional value and cost and to diets that are increasingly plant-based in order to meet further health and environmental goals, including the EAT-Lancet planetary health diet, to explore whether multiple goals could be achieved simultaneously. METHODS: We compared 13 dietary scenarios (2 current, 7 optimized, 3 increasingly plant-based, 1 EAT-Lancet) for nutrient content, cost, greenhouse gas emissions (GHGe), and water footprints, using the FAO food balance sheet, Indonesia Household Income and Expenditure Survey household food expenditure, food composition, life cycle assessment, food losses, and trade data. RESULTS: The diversity of modeled scenarios was higher than that of current consumption, reflecting nutritional deficiencies underlying Indonesia's burden of different forms of malnutrition. Nutrient intake targets were met best by nutrient- and cost-optimized diets, followed by the EAT-Lancet diet. Those diets also had high GHGe, although less than 40% of a scenario in which Indonesia would adopt a typical high-income country's diet. Only the low food chain diet had a GHGe below the 2050 target set by the EAT-Lancet commission. Its nutrient content was comparable to that of a no-dairy diet, slightly above those of fish-and-poultry and current diets, and somewhat below those of the EAT-Lancet diets. To meet nutrient needs, some animal-source foods had to be included. Costs of all except the optimized diets were above the current national average food expenditure. No scenario met all goals simultaneously. CONCLUSIONS: Indonesia's consumption of rice and unhealthy foods should decrease; food production, trade, and processing should prioritize diversification, (bio)fortification, and limiting environmental impacts; and consumer and institutional demands for healthy, nutritious, and sustainable foods should be stimulated. More granular data and tools are required to develop and assess more detailed scenarios to achieve multiple goals simultaneously.


Asunto(s)
Cambio Climático , Costos y Análisis de Costo , Dieta Saludable , Abastecimiento de Alimentos , Valor Nutritivo , Adolescente , Adulto , Niño , Dieta Saludable/economía , Femenino , Efecto Invernadero , Humanos , Indonesia , Lactante , Masculino , Persona de Mediana Edad
14.
J Anim Sci ; 99(10)2021 Oct 01.
Artículo en Inglés | MEDLINE | ID: mdl-34586403
15.
BMJ Open ; 11(9): e046200, 2021 09 27.
Artículo en Inglés | MEDLINE | ID: mdl-34580089

RESUMEN

OBJECTIVES: To compare global warming potential (GWP) of hospitals converting from single-use sharps containers to reusable sharps containers (SSC, RSC). Does conversion to RSC result in GWP reduction? DESIGN: Using BS PAS 2050:2011 principles, a retrospective, before/after intervention quantitative model together with a purpose-designed, attributional 'cradle-to-grave' life-cycle tool, were used to determine the annual greenhouse gas (GHG) emissions of the two sharps containment systems. Functional unit was total fill line litres (FLL) of sharps containers needed to dispose of sharps for 1-year period in 40 trusts. Scopes 1, 2 and 3 emissions were included. Results were workload-normalised using National Health Service (NHS) national hospital patient-workload indicators. A sensitivity analysis examined areas of data variability. SETTING: Acute care hospital trusts in UK. PARTICIPANTS: 40 NHS hospital Trusts using RSC. INTERVENTION: Conversion from SSC to RSC. SSC and RSC usage details in 17 base line trusts immediately prior to 2018 were applied to the RSC usage details of the 40 trusts using RSC in 2019. PRIMARY OUTCOME MEASURE: The comparison of GWP calculated in carbon dioxide equivalents (CO2e) generated in the manufacture, transport, service and disposal of 12 months, hospital-wide usage of both containment systems in the 40 trusts. RESULTS: The 40 trusts converting to RSC reduced their combined annual GWP by 3267.4 tonnes CO2e (-83.9%); eliminated incineration of 900.8 tonnes of plastic; eliminated disposal/recycling of 132.5 tonnes of cardboard and reduced container exchanges by 61.1%. GHG as kg CO2e/1000 FLL were 313.0 and 50.7 for SSC and RSC systems, respectively. A sensitivity analysis showed substantial GHG reductions within unit processes could be achieved, however, their impact on relevant final GWP comparison varied <5% from base comparison. CONCLUSIONS: Adopting RSC is an example of a sustainable purchasing decision that can assist trusts meet NHS GHG reduction targets and can reduce GWP permanently with minimal staff behavioural change.


Asunto(s)
Huella de Carbono , Gases de Efecto Invernadero , Dióxido de Carbono/análisis , Efecto Invernadero , Humanos , Estudios Retrospectivos , Medicina Estatal , Reino Unido
16.
Bioresour Technol ; 341: 125754, 2021 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-34411943

RESUMEN

This paper presents the greenhouse gas (GHG) emissions during ultrasonication of sludge and anaerobic digestion (AD) of the ultrasonicated sludge using mass-energy balance. Computation of the net energy (energy recovered - energy input) revealed that high solids concentration with low sonication specific energy provides positive net energy. Moreover, the GHG emissions can be minimised at low sonication specific energy input and high solids concentration compared to that of the control without sonication. Increase in temperature of sludge during sonication will reduce the energy input required for raising the sludge temperature to AD temperature and thus decreases the GHG emissions. With energy recovery from the methane produced in AD, the total GHG emissions can further be reduced, lower than that without energy recovery from methane.


Asunto(s)
Gases de Efecto Invernadero , Aguas del Alcantarillado , Anaerobiosis , Efecto Invernadero , Metano/análisis , Sonicación
17.
Nutrients ; 13(8)2021 Jul 22.
Artículo en Inglés | MEDLINE | ID: mdl-34444667

RESUMEN

Low-carbon diets can counteract climate change and promote health if they are nutritionally adequate, affordable and culturally acceptable. This study aimed at developing sustainable diets and to compare these with the EAT-Lancet diet. The Swedish national dietary survey Riksmaten Adolescents 2016-2017 was used as the baseline. Diets were optimized using linear programming for four dietary patterns: omnivores, pescatarians, vegetarians and vegans. The deviation from the baseline Riksmaten diet was minimized for all optimized diets while fulfilling nutrient and climate footprint constraints. Constraining the diet-related carbon dioxide equivalents of omnivores to 1.57 kg/day resulted in a diet associated with a reduction of meat, dairy products, and processed foods and an increase in potatoes, pulses, eggs and seafood. Climate-friendly, nutritionally adequate diets for pescatarians, vegetarians and vegans contained fewer foods and included considerable amounts of fortified dairy and meat substitutes. The optimized diets did not align very well with the food-group pattern of the EAT-Lancet diet. These findings suggest how to design future diets that are climate-friendly, nutritionally adequate, affordable, and culturally acceptable for Swedish adolescents with different dietary patterns. The discrepancies with the EAT diet indicate that the cultural dietary context is likely to play an important role in characterizing sustainable diets for specific populations.


Asunto(s)
Cambio Climático , Dieta Saludable , Dieta Vegetariana , Valor Nutritivo , Carne Roja , Alimentos Marinos , Adolescente , Conducta del Adolescente , Fenómenos Fisiológicos Nutricionales de los Adolescentes , Factores de Edad , Huella de Carbono , Dieta Saludable/efectos adversos , Dieta Vegana , Ingestión de Energía , Conducta Alimentaria , Preferencias Alimentarias , Efecto Invernadero , Humanos , Estado Nutricional , Ingesta Diaria Recomendada , Carne Roja/efectos adversos , Alimentos Marinos/efectos adversos , Suecia
18.
J Environ Manage ; 297: 113400, 2021 Nov 01.
Artículo en Inglés | MEDLINE | ID: mdl-34346397

RESUMEN

Shelterbelts are rows of trees planted around farmyards and field for protection against soil erosion, promotion of biodiversity and wildlife habitat. Additionally, to carbon sequestration through growth in tree biomass and carbon sinks in agricultural soil. In recent years, removal of shelterbelts has become more common, as crop land is preferred under higher crop prices, resulting in increased GHG emissions and decreases in carbon sinks. It is likely that landowners are making decisions without the knowledge of carbon sequestered by these trees. In this study, the level of carbon sequestration for the six common shelterbelt tree species found in Saskatchewan (hybrid poplar, green ash, Manitoba maple, Scots pine, white spruce, and caragana) was estimated using a carbon - life cycle analysis method. Net amount of carbon sequestered was estimated for five sequestration/emission stages - 1) seedling production, 2) transportation of seedlings to farm, 3) planting, 4) maintenance, and 5) growth of shelterbelts on farm. Since some landowners are removing shelterbelts, a removal stage was also included. During removal of shelterbelts, CO2 emissions were produced through: (i) physical process of removing the trees and subsequent burning of the wood; and (ii) loss of soil carbon after the removal over a long period of time. The functional unit for the analysis was one linear kilometer of shelterbelt, the normal structure of shelterbelts on agricultural land. All emissions/sequestration levels were measured as carbon dioxide (CO2) by multiplying the molecular weight of carbon dioxide to that of carbon (44/12). Other than the growth stage of shelterbelts, all other stages contributed net greenhouse gas emissions, which offset by carbon sequestration during tree growth. Hybrid poplar is a rapidly growing tree and sequesters the most carbon of the six species in all soil zones. A one km long hybrid poplar shelterbelt sequestered upwards of 1923 t CO2 by age 60 years in the Brown soil zone, compared to 2086 t CO2 over the same period in the Black soil zone. In comparison, in the Brown soil zone, Manitoba maple and white spruce sequestered 756 and 732 t CO2, respectively over the same period. If a landowner decides to remove a 60-year-old shelterbelt, 1205 t CO2 is lost within a short period after removal, whereas 718 t of remaining CO2 is retained as dead organic matter, which is slowly released over a period. Although field shelterbelts may emit greenhouse gases in the earlier stages of development, overall, they are net sinks of carbon and can therefore play a significant role in Canada's plan to reduce GHG emissions from agriculture.


Asunto(s)
Gases de Efecto Invernadero , Agricultura , Animales , Ciclo del Carbono , Dióxido de Carbono/análisis , Secuestro de Carbono , Efecto Invernadero , Gases de Efecto Invernadero/análisis , Estadios del Ciclo de Vida , Saskatchewan , Suelo
20.
Sci Total Environ ; 800: 149508, 2021 Dec 15.
Artículo en Inglés | MEDLINE | ID: mdl-34391143

RESUMEN

Greenhouse gas (GHG) emissions including carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) created via wastewater treatment processes are not easily modeled given the non-linearity and complexity of biological processes. These factors are also impacted by limited data availability making the development of artificial data generation algorithms, such as a generative adversarial network (GAN), useful for determination of GHG emission rate estimates (EREs). The main objective of this study was to develop a hybrid approach of using GAN and regression modelling to determine GHG EREs from a cold-region biological nutrient removal (BNR) municipal wastewater treatment plant (MWTP) in which the aerobic reactor has previously been established as the main GHG emission source. To our knowledge, this is the first application of GAN used for MWTP modelling purposes. The EREs were generated from laboratory-scale reactors used in conjunction with facility-monitored operating parameters to develop the GAN and regression models. Results showed that regression models provided reasonable EREs using parameters including hydraulic retention time (HRT), temperature, total organic carbon, and dissolved oxygen (DO) concentrations for CO2 EREs; HRT, temperature, DO and phosphate (PO43-) concentrations for CH4 EREs; and temperature, DO, and nitrogen (nitrite, nitrate, and ammonium) concentrations for N2O EREs. Additionally, the addition of 100 GAN-created virtual data points improved regression model metrics including increased correlation coefficient and index agreement values, and decreased root mean square error values. Clearly, virtual data augmentation using GAN is a valuable resource in supplementation of limited data for improved modelling outcomes. Genetic algorithm optimization was also used to determine operating parameter modifications resulting in potential for minimization (or maximization) of GHG emissions.


Asunto(s)
Gases de Efecto Invernadero , Dióxido de Carbono/análisis , Efecto Invernadero , Gases de Efecto Invernadero/análisis , Metano/análisis , Óxido Nitroso/análisis , Aguas Residuales
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