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4.
Water Res ; 170: 115327, 2020 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-31810031

RESUMO

Releases of greenhouse gases (GHGs) from the subsurface can result in atmospheric emissions and the degradation of water quality. These effects require attention in today's changing climate to properly quantify emissions, reduce risk and inform sound policy decisions. Flowing subsurface GHGs, including methane and carbon dioxide, present a risk in the form of two environmental expressions: i) to the atmosphere (surface expression) and ii) to shallow groundwater (aqueous expression). Results based on high-resolution observations in an analog experimental system and analytical modelling show that these expressions depend on the rate of gas flow and the velocity of the flowing groundwater. In deeper systems, the emission of flowing subsurface GHGs could be significantly limited by dissolution into groundwater, adversely impacting water resources without surficial evidence of an underlying issue. This work shows that mass transfer in the subsurface must be considered to quantify, monitor and mitigate risks of leaking subsurface GHGs.


Assuntos
Gases de Efeito Estufa , Dióxido de Carbono , Efeito Estufa , Metano , Óxido Nitroso
5.
Bioresour Technol ; 297: 122493, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31836278

RESUMO

The decarbonization of agriculture faces many challenges and has received a level of attention insufficient to abate the worst effects of climate change and ensure a sustainable bioeconomy. Agricultural emissions are caused both by fossil-intensive fertilizer use and land-use change, which in turn are driven in part by increasing demand for dietary protein. To address this challenge, we present a synergistic system in which organic waste-derived biogas (a mixture of methane and carbon dioxide) is converted to dietary protein and ammonia fertilizer. This system produces low-carbon fertilizer inputs alongside high-quality protein, addressing the primary drivers of agricultural emissions. If the proposed system were implemented across the United States utilizing readily available organic waste from municipal wastewater, landfills, animal manure, and commercial operations, we estimate 30% of dietary protein intake and 127% of ammonia usage could be displaced while reducing land use, water consumption, and greenhouse gas emissions.


Assuntos
Fertilizantes , Esterco , Agricultura , Amônia , Animais , Proteínas na Dieta , Efeito Estufa , Metano
6.
Food Chem ; 307: 125521, 2020 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-31655264

RESUMO

The essential oils and antioxidant activity of four Thymus species were evaluated under five light spectra (namely, red, blue, red-blue, white, and greenhouse condition). The highest essential oil yield (4.17%) was observed under red light in T. migricus, while the lowest (1.05%) was observed in T. carmanicus under greenhouse conditions. Light quality also led to difference in essential oil constituents. The highest thymol (66%) was found in T. migricus exposed to blue light, while the least (1.69%) was observed in T. kotschyanus grown under red-blue light. The LED treatments did not induce any significant effect on carvacrol of Thymus species in comparison to the greenhouse condition. Finally, the analysis of variance indicates that the effect of light varied with the studied species. T. migricus performed the highest antioxidant capacity (IC50 = 176.8 µg/mL) under blue light. Overall, essential oil components as well as antioxidants showed significant responses to light emitting diodes wavelengths.


Assuntos
Antioxidantes/metabolismo , Luz , Timol/metabolismo , Thymus (Planta)/química , Análise de Variância , Antioxidantes/química , Cromatografia Gasosa , Análise por Conglomerados , Efeito Estufa , Óleos Voláteis/química , Análise de Componente Principal , Timol/química , Thymus (Planta)/crescimento & desenvolvimento , Thymus (Planta)/metabolismo
7.
J Environ Manage ; 254: 109796, 2020 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-31731026

RESUMO

Plastic films can be considered as a high-value auxiliary material in agriculture with multiple important uses to fulfil, including covering films in greenhouse cultivation system. Such an application enables several benefits and, therefore, it is going through an important upsurge, especially in regions where protected crop cultivation is highly widespread. However, the increased demand for these covering films arouses concerns for their post-use treatment with regard to both the consumption of Non-Renewable Primary Energy (NRPE) resources and the emission of Greenhouse Gases (GHGs). Therefore, environmental analysis is needed to find and follow cleaner paths for the management and treatment of this kind of Agricultural Plastic Waste (APW), especially in the light of the gap currently existing in the specialised literature. In this context, this paper reports upon findings from a combined Life Cycle Assessment (LCA) of single environmental issues (i.e., energy and water consumption, and GHG emissions) applied to a Sicilian firm, representative of APW collection and recycling to obtain Low-Density Polyethylene (LDPE) granules. The results showed that electricity consumption for the whole recycling process is the most NRPE resource demanding and the most GHG emitting input item. Moreover, the washing phase of disused covering films is the highest water demanding within the recycling process. Potential improvements could be achieved by shifting from fossil energy source to renewable one. The installation of a wind power plant would lead to around 56% and 85% reduction in NRPE resource exploitation and GHG emission, respectively. Finally, despite the huge consumption of water and NRPE resources and the resulting GHG emissions, the production of recycled-LDPE granules is far more sustainable than the virgin counterpart.


Assuntos
Plásticos , Reciclagem , Agricultura , Fontes Geradoras de Energia , Efeito Estufa , Centrais Elétricas
8.
Environ Manage ; 64(6): 772-782, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31748948

RESUMO

During the last decade, China's agro-food production has increased rapidly and been accompanied by the challenge of increasing greenhouse gas (GHG) emissions and other environmental pollutants from fertilizers, pesticides, and intensive energy use. Understanding the energy use and environmental impacts of crop production will help identify environmentally damaging hotspots of agro-production, allowing environmental impacts to be assessed and crop management strategies optimized. Conventional farming has been widely employed in wolfberry (Lycium barbarum) cultivation in China, which is an important cash tree crop not only for the rural economy but also from an ecological standpoint. Energy use and global warming potential (GWP) were investigated in a wolfberry production system in the Yellow River irrigated Jingtai region of Gansu. In total, 52 household farms were randomly selected to conduct the investigation using questionnaires. Total energy input and output were 321,800.73 and 166,888.80 MJ ha-1, respectively, in the production system. The highest share of energy inputs was found to be electricity consumption for lifting irrigation water, accounting for 68.52%, followed by chemical fertilizer application (11.37%). Energy use efficiency was 0.52 when considering both fruit and pruned wood. Nonrenewable energy use (88.52%) was far larger than the renewable energy input. The share of GWP of different inputs were 64.52% electricity, 27.72% nitrogen (N) fertilizer, 5.07% phosphate, 2.32% diesel, and 0.37% potassium, respectively. The highest share was related to electricity consumption for irrigation, followed by N fertilizer use. Total GWP in the wolfberry planting system was 26,018.64 kg CO2 eq ha-1 and the share of CO2, N2O, and CH4 were 99.47%, 0.48%, and negligible respectively with CO2 being dominant. Pathways for reducing energy use and GHG emission mitigation include: conversion to low carbon farming to establish a sustainable and cleaner production system with options of raising water use efficiency by adopting a seasonal gradient water pricing system and advanced irrigation techniques; reducing synthetic fertilizer use; and policy support: smallholder farmland transfer (concentration) for scale production, credit (small- and low-interest credit) and tax breaks.


Assuntos
Aquecimento Global , Lycium , Agricultura , Carbono , China , Fertilizantes , Efeito Estufa , Metano , Óxido Nitroso
9.
Waste Manag Res ; 37(12): 1282-1290, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31674292

RESUMO

Greenhouse gas emissions resulting from municipal solid waste management activities and the associated climate change impacts are getting great attention worldwide. This study investigates greenhouse gas emissions and their distribution during waste collection and transport activities in the Dammam region of Saudi Arabia. Greenhouse gas emissions and associated global warming factors were estimated based on diesel fuel consumption during waste collection and transport activities. Then, waste collection and transport data were used to parameterise a mechanistic collection model that can be used to estimate and predict future fuel consumption and greenhouse gas emissions. For the collection and transport of municipal waste in the study area, the average associated total greenhouse gas emissions were about 24,935 tCO2-eq. Global warming factors for three provinces were estimated as 25.23 kg CO2-eq t-1, 25.04 kg CO2-eq t-1, and 37.15 kg CO2-eq t-1, respectively. Lastly, the American Meteorological Society/Environmental Protection Agency Regulatory Model (AERMOD) modelling system was used to estimate the atmospheric dispersion of greenhouse gas emissions. Model results revealed that the maximum daily greenhouse gas concentrations ranged between 0.174 and 97.3 mg m-3, while annual average greenhouse gas concentrations were found to be between 0.012 and 27.7 mg m-3 within the study domain. The highest greenhouse gas concentrations were observed for the regions involving the municipal solid waste collection routes owing to their higher source emission rates.


Assuntos
Gases de Efeito Estufa , Eliminação de Resíduos , Dióxido de Carbono , Aquecimento Global , Efeito Estufa , Resíduos Sólidos
10.
J Environ Manage ; 250: 109363, 2019 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-31703242

RESUMO

The past two decades have witnessed growing global concern about excessive greenhouse gas (GHG) emissions by reservoirs and the development of hydropower. Literature review showed that life cycle GHG emissions per energy production of collected global dataset ranged from 0.04 to 237.0 gCO2eq/kW⋅h, with a mean of 25.8 ±â€¯3.0 gCO2eq/kW⋅h. Synthesis from the China's five largest hydro-projects and other publications estimated that the large- and mid-scale hydro-projects in China had a carbon footprint between 6.2 gCO2eq/kWh and 34.6 gCO2eq/kWh, with a mean value of 19.2 ±â€¯6.8 gCO2eq/kWh (mean ±â€¯sd.). Over 80% of the carbon footprint of the hydro-projects could be conservatively allocated to hydroelectricity generation, while the rest could then be allocated to flood control services. In the Three Gorges Dam Project, the allocated life cycle GHG emissions per energy production of its hydroelectricity production was estimated to be 17.8 gCO2eq/kW⋅h. GHG emissions from reservoir sediments and in the phase of operation and maintenance were still uncertain. There is still a need of in-depth research on reservoir carbon cycling to quantify net reservoir GHG emissions.


Assuntos
Pegada de Carbono , Gases de Efeito Estufa , China , Inundações , Efeito Estufa
13.
Environ Sci Technol ; 53(22): 12989-12998, 2019 Nov 19.
Artigo em Inglês | MEDLINE | ID: mdl-31626735

RESUMO

Digestate and biochar can be land applied to sequester carbon and improve net primary productivity, but the achievable scale is tied to expected growth in bioenergy production and land available for application. We use an attributional life-cycle assessment approach to estimate the greenhouse gas (GHG) emissions and carbon storage potential of biochar, digested solids, and composted digested solids generated from organic waste in California as a test case. Our scenarios characterize changes in organic waste production, bioenergy facility build-out, bioenergy byproduct quality, and soil response. Moderate to upper bound growth in the bioenergy sector with annual byproduct disposal over 100 years could provide a cumulative GHG offset of 50-400 MMTCO2 equiv, with an additional 80-300 MMTC sequestered in soils. This corresponds to net GHG mitigation over 100 years equivalent to 340-1500 MMTCO2 equiv (80-350% of California's annual emissions). In most scenarios, there is sufficient working land to apply all available biochar and digestate, although land becomes a constraint if the soil's rest time between applications increases from 5 to 15 years.


Assuntos
Carbono , Efeito Estufa , California , Carvão Vegetal , Solo
14.
Environ Sci Pollut Res Int ; 26(32): 33702-33714, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31595410

RESUMO

In this study, we aimed at determining greenhouse gas (GHG) (CO2, CH4, and N2O) fluxes exchange between the soil collected from sites dominated by different vegetation types (Calamagrostis epigeios, Phragmites australis, and Carex schnimdtii) in nitrogenous loaded riparian wetland and the atmosphere. The intact soil columns collected from the wetland were incubated in laboratory and continuously treated with [Formula: see text]-enriched water simulating downward surface water percolating through the soil to become groundwater in a natural system. This study revealed that the soil collected from the site dominated by C. epigeios was net CO2 and N2O sources, whereas the soil from P. australis and C. schnimdtii were net sinks of CO2 and N2O, respectively. The soil from the site dominated by C. schnimdtii had the highest climate impact, as it had the highest global warming potential (GWP) compared with the other sites. Our study indicates that total organic carbon and [Formula: see text] concentration in the soil water has great influence on GHG fluxes. Carbon dioxide (CO2) and N2O fluxes were accelerated by the availability of higher [Formula: see text] concentration in soil water. On the other hand, higher [Formula: see text] concentration in soil water favors CH4 oxidation, hence the low CH4 production. Temporally, CO2 fluxes were relatively higher in the first 15 days and reduced gradually likely due to a decline in organic carbon. The finding of this study implies that higher [Formula: see text] concentration in wetland soil, caused by human activities, could increase N2O and CO2 emissions from the soil. This therefore stresses the importance of controls of [Formula: see text] leaching in the mitigation of anthropogenic N2O and CO2 emissions.


Assuntos
Monitoramento Ambiental , Gases de Efeito Estufa/análise , Nitratos/análise , Áreas Alagadas , Atmosfera , Dióxido de Carbono/análise , Clima , Aquecimento Global , Efeito Estufa , Água Subterrânea , Estudos Longitudinais , Metano/análise , Nitrogênio , Óxido Nitroso/análise , Poaceae , Solo
15.
Environ Sci Technol ; 53(21): 12168-12176, 2019 Nov 05.
Artigo em Inglês | MEDLINE | ID: mdl-31600434

RESUMO

Non-CO2 greenhouse gas (GHG) emissions account for about 1/4 of global GHG emissions, and the trend of these emissions, as well as their mitigation potential and abatement cost, are of interest to both scientific researchers and decision makers. We present an integrated model, China Multigas Optimal Reduction Evaluation model (China-MORE), of the nitrous oxide (N2O), methane (CH4), and fluorinated gases (F-gases) emissions of China, with which we analyze the non-CO2 emission reduction implications of China's Paris pledges. We find that China's non-CO2 emissions can peak before 2030 under its Paris pledges, where the cobenefit of coal control policy is the largest contributor to this emissions trajectory due to reduction of CH4 from coal mines. Based on the mitigation cost curve, we show that while the non-CO2 emission reductions are cost-effective at a lower reduction rate, they can only be reduced up to 60-70% due to physical constraints of the reduction technologies, leaving 1.4 Gt CO2-eq of residual emissions in 2050. The growth of non-CO2 emissions in China is largely driven by household consumption of cooling technologies, vehicles, and food. Our findings imply that deep reductions can only be achieved through the deployment of mitigation technologies at a reasonable cost, along with policies to induce behavioral change.


Assuntos
Gases de Efeito Estufa , Dióxido de Carbono , China , Efeito Estufa , Metano , Óxido Nitroso
17.
Environ Sci Technol ; 53(20): 12121-12129, 2019 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-31542927

RESUMO

California's building energy codes (Title 24, Part 6), updated triennially since 1978, are the most stringent in the nation. The aim of California contemporary energy policy in general, and the state's building codes and standards in particular, is the reduction of greenhouse gas emissions. The state has identified residential designs that "bring value to the grid" as a key constituent of this effort. This research quantifies the marginal costs that code requirements add to new residential construction, the quantity of carbon emissions and abatement expected at a statewide level, and the marginal abatement cost of homes built under the new 2019 standards relative to those built under the prior code. We model hourly energy consumption and emissions (2020-2050) for seven residential building types representative of California production housing for each of California's 16 climate zones. Costs and benefits of each housing type are analyzed under a 30-year timeframe. Our results indicate that the 2019 code allows for a wide range of emission profiles, including very high long-term emissions resulting from the use of natural gas and under high leak rates. The significant and previously unreported impact of pre-meter natural gas leaks emphasizes the challenges that natural gas creates with respect to meeting California's long-term GHG reduction goals. Marginal abatement costs are dependent on natural gas leak rates, but consistently indicate that all-electric homes represent the first-best policy option for residential sector GHG abatement in California.


Assuntos
Gases de Efeito Estufa , California , Carbono , Efeito Estufa , Habitação , Gás Natural
19.
Environ Sci Technol ; 53(20): 12141-12149, 2019 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-31553580

RESUMO

Conversion of wastes to biofuels is a promising route to provide renewable low-carbon fuels, based on a low- or negative-cost feedstock, whose use can avoid negative environmental impacts of conventional waste treatment. However, current policies that employ LCA as a quantitative measure are not adequate for assessing this type of fuel, given their cross-sector interactions and multiple potential product/service streams (energy, fuels, materials, waste treatment service). We employ a case study of butanol and ethanol production from mixed municipal solid waste to demonstrate the challenges in using life cycle assessment to appropriately inform decision-makers. Greenhouse gas emissions results vary from -566 gCO2 eq/MJbiofuel (under US policies that employ system expansion approach) to +86 gCO2 eq/MJbiofuel and +23 gCO2 eq/MJbiofuel (under initial and current EU policies that employ energy-based allocation), relative to gasoline emissions of +94 gCO2 eq. LCA methods used in existing policies thus provide contradictory information to decision-makers regarding the potential for waste-based biofuels. A key factor differentiating life cycle assessment methodologies is the inclusion of avoided impacts of conventional waste treatment in US policies and their exclusion in EU policies. Present EU rules risk discouraging the valorisation of wastes to biofuels thus forcing waste toward lower-value treatment processes and products.


Assuntos
Gases de Efeito Estufa , Resíduos Sólidos , Biocombustíveis , Butanóis , Etanol , Efeito Estufa
20.
Environ Sci Pollut Res Int ; 26(32): 33416-33426, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31522393

RESUMO

Fluxes of methane (CH4) and nitrous oxide (N2O) from two rice varieties, Huayou 14 and Hanyou 8, were monitored using closed chamber/gas chromatography method. Huayou 14 is a commonly grown variety of rice whereas Hanyou 8 is a water-saving and drought-resistant rice (WDR) variety. Low soil volumetric water content (VWC) existed in the treatments on the slope (W5 < W4 < W3 < W2). On the slope, rice yields of Hanyou 8 decreased by 12-39%, and Huayou 14 by 11-46% as compared to the plots on the flat. The total compatible solutes in Hanyou 8 had a greater variational range than Huayou 14. Compared to W1, CH4 emissions from W2-W5 decreased by 58-86% in Hanyou 8 and 38-86% in Huayou 14, whereas those of N2O increased by 26-121% in Hanyou 8 and 49-189% in Huayou 14 across both two seasons, which was mainly because the VWC varied in W2-W5 treatment. Under the treatments in the slope (W2, W3, W4, and W5), the global warming potential (GWP) was dominated by N2O emissions, which accounted for 69-90% of the GWP. Hanyou 8 had greater tolerance for water stress than Huayou 14 did, as evident from the smaller reductions in rice yield and greater variational range of total compatible solutes content. Water stress could reduce CH4 emissions but decrease N2O emissions for both rice varieties. This results suggest that planting WDR varieties under water shortage irrigation (such as W4, W5) will be able to maintain rice yields and reduce the GWP with less water.


Assuntos
Agricultura/estatística & dados numéricos , Gases de Efeito Estufa/análise , Oryza , Agricultura/métodos , China , Secas , Aquecimento Global , Efeito Estufa , Metano/análise , Óxido Nitroso/análise , Estações do Ano , Solo/química
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