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1.
PLoS One ; 17(5): e0267693, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35511811

RESUMO

Methane (CH4) emission from pig slurry is a large contributor to the climate footprint of livestock production. Acidification of excreta from livestock animals with sulfuric acid, reduce CH4 emission and is practiced at many Danish farms. Possible interaction effects with other acidic agents or management practices (e.g. frequent slurry removal and residual slurry acidification) have not been fully investigated. Here we assessed the effect of pig slurry acidification with a range of organic and inorganic acids with respect to their CH4 inhibitor potential in several batch experiments (BS). After careful selection of promising CH4 inhibitors, three continuous headspace experiments (CHS) were carried out to simulate management of manure in pig houses. In BS experiments, more than <99% CH4 reduction was observed with HNO3 treatment to pH 5.5. Treatments with HNO3, H2SO4, and H3PO4 reduced CH4 production more than acetic acid and other organic acids when acidified to the same initial pH of 5.5. Synergistic effects were not observed when mixing inorganic and organic acids as otherwise proposed in the literature, which was attributed to the high amount of acetic acid in the slurry to start with. In the CHS experiments, HNO3 treatment reduced CH4 more than H2SO4, but increased nitrous oxide (N2O) emission, particularly when the acidification target pH was above 6, suggesting considerable denitrification activity. Due to increased N2O emission from HNO3 treatments, HNO3 reduced total CO2-eq by 67%, whereas H2SO4 reduced CO2-eq by 91.5% compared to untreated slurry. In experiments with daily slurry addition, weekly slurry removal, and residual acidification, HNO3 and H2SO4 treatments reduced CO2-eq by 27% and 48%, respectively (not significant). More cycles of residual acidification are recommended in future research. The study provides solid evidence that HNO3 treatment is not suitable for reducing CO2-eq and H2SO4 should be the preferred acidic agent for slurry acidification.


Assuntos
Gases de Efeito Estufa , Ácidos , Animais , Dióxido de Carbono , Concentração de Íons de Hidrogênio , Esterco/análise , Metano/análise , Óxido Nitroso , Suínos
2.
Science ; 376(6593): 597-603, 2022 05 06.
Artigo em Inglês | MEDLINE | ID: mdl-35511968

RESUMO

International trade separates consumption of goods from related environmental impacts, including greenhouse gas emissions from agriculture and land-use change (together referred to as "land-use emissions"). Through use of new emissions estimates and a multiregional input-output model, we evaluated land-use emissions embodied in global trade from 2004 to 2017. Annually, 27% of land-use emissions and 22% of agricultural land are related to agricultural products ultimately consumed in a different region from where they were produced. Roughly three-quarters of embodied emissions are from land-use change, with the largest transfers from lower-income countries such as Brazil, Indonesia, and Argentina to more industrialized regions such as Europe, the United States, and China. Mitigation of global land-use emissions and sustainable development may thus depend on improving the transparency of supply chains.


Assuntos
Comércio , Gases de Efeito Estufa , Agricultura , China , Europa (Continente) , Internacionalidade
3.
Nature ; 605(7908): 90-96, 2022 05.
Artigo em Inglês | MEDLINE | ID: mdl-35508780

RESUMO

Ruminant meat provides valuable protein to humans, but livestock production has many negative environmental impacts, especially in terms of deforestation, greenhouse gas emissions, water use and eutrophication1. In addition to a dietary shift towards plant-based diets2, imitation products, including plant-based meat, cultured meat and fermentation-derived microbial protein (MP), have been proposed as means to reduce the externalities of livestock production3-7. Life cycle assessment (LCA) studies have estimated substantial environmental benefits of MP, produced in bioreactors using sugar as feedstock, especially compared to ruminant meat3,7. Here we present an analysis of MP as substitute for ruminant meat in forward-looking global land-use scenarios towards 2050. Our study complements LCA studies by estimating the environmental benefits of MP within a future socio-economic pathway. Our model projections show that substituting 20% of per-capita ruminant meat consumption with MP globally by 2050 (on a protein basis) offsets future increases in global pasture area, cutting annual deforestation and related CO2 emissions roughly in half, while also lowering methane emissions. However, further upscaling of MP, under the assumption of given consumer acceptance, results in a non-linear saturation effect on reduced deforestation and related CO2 emissions-an effect that cannot be captured with the method of static LCA.


Assuntos
Dióxido de Carbono , Gases de Efeito Estufa , Animais , Bovinos , Dieta , Efeito Estufa , Humanos , Gado , Carne , Ruminantes
4.
BMC Public Health ; 22(1): 877, 2022 May 03.
Artigo em Inglês | MEDLINE | ID: mdl-35501799

RESUMO

OBJECTIVE: This study investigates nutritional quality, environmental impact and costs of foods and drinks and their consumption in daily diets according to the degree of processing across the Dutch population. DESIGN: The NOVA classification was used to classify the degree of processing (ultra-processed foods (UPF) and ultra-processed drinks (UPD)). Food consumption data were derived from the Dutch National Food Consumption Survey 2012-2016. Indicators assessed were nutritional quality (saturated fatty acids (SFA), sodium, mono and disaccharides (sugar), fibre and protein), environmental impact (greenhouse gas (GHG) emissions and blue water use) and food costs. SETTING: The Netherlands. PARTICIPANTS: Four thousand three hundred thirteen Dutch participants aged 1 to 79 years. RESULTS: Per 100 g, UPF were more energy-dense and less healthy than unprocessed or minimally processed foods (MPF); UPF were associated with higher GHG emissions and lower blue water use, and were cheaper. The energy and sugar content of UPD were similar to those of unprocessed or minimally processed drinks (MPD); associated with similar GHG emissions but blue water use was less, and they were also more expensive. In the average Dutch diet, per 2000 kcal, ultra-processed foods and drinks (UPFD) covered 29% (456 g UPF and 437 g UPD) of daily consumption and 61% of energy intake. UPFD consumption was higher among children than adults, especially for UPD. UPFD consumption determined 45% of GHG emissions, 23% of blue water use and 39% of expenses for daily food consumption. UPFD consumption contributed 54% to 72% to daily sodium, sugar and SFA intake. CONCLUSIONS: Compared with unprocessed or minimally processed foods and drinks, UPF and UPD were found to be less healthy considering their high energy, SFA, sugar and sodium content. However, UPF were associated higher GHG emissions and with less blue water use and food costs. Therefore daily blue water use and food costs might increase if UPF are replaced by those unprocessed or minimally processed. As nutritional quality, environmental impacts and food costs relate differently to the NOVA classification, the classification is not directly applicable to identify win-win-wins of nutritional quality, environmental impact and costs of diets.


Assuntos
Dieta , Gases de Efeito Estufa , Adulto , Criança , Meio Ambiente , Humanos , Países Baixos , Valor Nutritivo , Sódio , Açúcares , Água
5.
Environ Monit Assess ; 194(6): 413, 2022 May 10.
Artigo em Inglês | MEDLINE | ID: mdl-35536433

RESUMO

In situ coal fires significantly pollute the environment in many countries of the world. Monitoring these pollutants is challenging due to extensive area coverage and spatial variations. Thus, the present study demonstrates the method of deriving the spatial and temporal profiles of columnar density of three major greenhouse gases (carbon monoxide (CO), sulfur dioxide (SO2), and nitrogen dioxide (NO2)) in an in situ coal fire region (Jharia coalfield (JCF), India) using high-resolution satellite data (TROPOMI) of the European Space Agency (ESA). The study also demonstrates a new methodology for estimating greenhouse gas emissions from in situ coal burning. JCF is one of the significant polluted mining regions with multiple in situ coal fire pockets. The columnar density of the gaseous pollutants in the mining region was compared with the same in the rural, urban, and forest regions to identify the major emission inventories. The study results indicated that coal fire is the major source of CO emission in the region, as the CO was high in the fire regions compared to that of the non-fire regions. But, the major source of NO2 is the traffic, as the NO2 was high in the city area as compared to other regions. The spatial profile of SO2 does not reveal the specific emission sources. The study results indicated that TROPOMI onboard satellite sensors could be effectively used for deriving the spatial profiles of greenhouse gaseous in coal fire regions, which further assist in identifying the emission inventories. Furthermore, the satellite-based Earth observations offer information to understand and manage the greenhouse gas emissions over a large area.


Assuntos
Poluentes Atmosféricos , Incêndios , Gases de Efeito Estufa , Poluentes Atmosféricos/análise , Carvão Mineral , Monitoramento Ambiental/métodos , Dióxido de Nitrogênio , Tecnologia de Sensoriamento Remoto , Dióxido de Enxofre/análise
6.
Nat Commun ; 13(1): 2479, 2022 May 05.
Artigo em Inglês | MEDLINE | ID: mdl-35513425

RESUMO

Climate change has significant implications for macro-economic growth. The impacts of greenhouse gases and anthropogenic aerosols on economies via altered annual mean temperature (AMT) have been studied. However, the economic impact of land-use and land-cover change (LULCC) is still unknown because it has both biogeochemical and biogeophysical impacts on temperature and the latter differs in latitudes and disturbed land surface types. In this work, based on multi-model simulations from the Coupled Model Intercomparison Project Phase 6, contrasting influences of biogeochemical and biogeophysical impacts of historical (1850-2014) LULCC on economies are found. Their combined effects on AMT result in warming in most countries, which harms developing economies in warm climates but benefits developed economies in cold climates. Thus, global economic inequality is increased. Besides the increased AMT by the combined effects, day-to-day temperature variability is enhanced in developing economies but reduced in developed economies, which further deteriorates global economic inequality.


Assuntos
Mudança Climática , Gases de Efeito Estufa , Aerossóis , Temperatura
8.
Water Res ; 218: 118501, 2022 Jun 30.
Artigo em Inglês | MEDLINE | ID: mdl-35523036

RESUMO

Reducing methane emission is of great importance to control the global greenhouse effect. Dissimilatory iron reduction (DIR) coupling of organic matter decomposition may suppress methane production via reducing primary electron donors available for methanogenesis. However, during DIR, the amorphous iron oxides (e.g., ferrihydrite) are easy to transform into more stable crystalline iron minerals, which slowdowns the rate of DIR. Humic substance (HS) with redox activity has been extensively reported to facilitate DIR via "electron shuttles" mechanism, yet little known about the effect of HS on mediating the mineralization of iron oxides and the subsequent influences on DIR and methanogenesis. To clarify this, ferrihydrite and fulvic acid (FA) (as the model substance of HS) were supplied to anaerobic methanogenesis systems. Results showed that FA could significantly decrease the formation of crystalline iron oxides, enhance DIR rate by 13.72% and suppress methanogenesis by 25.13% compared to ferrihydrite supplemented only. By X-ray absorption spectra analysis, it was found that FA could complex with ferrihydrite via forming a Fe-C/O structure on the second shell of Fe atom. Quantum chemical calculation further confirmed that FA reduced the adsorption energy between Fe(II) and ferrihydrite. Our study suggested that rational use of HS to mediate mineralization pathway of iron oxides could efficiently improve the availability of iron oxides to drive DIR and control the conversion of organics into CH4 in natural or engineered systems.


Assuntos
Gases de Efeito Estufa , Benzopiranos , Compostos Férricos/metabolismo , Substâncias Húmicas , Ferro/química , Metano , Oxirredução , Óxidos
9.
Water Res ; 218: 118520, 2022 Jun 30.
Artigo em Inglês | MEDLINE | ID: mdl-35525032

RESUMO

Coastal wetland reclamation contributed to development of aquaculture industry, and the residual bait accumulation in aquaculture processes could influence biogeochemical elements cycling, which threaten ecological functions and services in aquaculture and adjacent ecosystems. However, systematic studies for changes in sediment microbial community structure and greenhouse gasses (GHGs) production, as well as environmental parameters following bait input at time scale are still rare. A 90-day incubation experiment was conducted using sediment collected from coastal wetland in Qi'ao Island in southern China, followed by the observations of temporal variations of physicochemical properties, sediment microbial community, and GHGs production in response to different amounts of bait input (0, 20, and 40 mg bait g-1 wet sediment). The results showed that dissolved oxygen of overlying water was profoundly decreased owing to bait input, while dissolved organic carbon of overlying water and several sediment properties (e.g., organic matter, sulfide, and ammonium) varied in reverse patterns. Meanwhile, bait input led to significant loss of microbial community richness and diversity, and strongly altered microbial compositions from aerobic, slow-growing, and oligotrophic (Actinobacteriota, Chloroflexi, and Acidobacteriota) to anaerobic, fast-growing, and copiotrophic (Firmicutes and Bacteroidota). Moreover, both GHGs production and global warming potential were significantly enhanced by bait input, implying that aquaculture ecosystem is an important hotspot for global GHGs emission. Overall, bait input triggered quick responses of physicochemical properties, sediment microbial community, and GHGs production, followed by long-term resilience of the ecosystem. This study could provide new insight into temporal interactive effects of bait input on physicochemical properties, microbial community, and GHGs production, which can enhance the understanding of the temporal dynamics and ecological impacts of coastal aquaculture activities and emphasize the necessity of sustainable assessment and management in aquaculture ecosystems.


Assuntos
Gases de Efeito Estufa , Microbiota , Gases de Efeito Estufa/análise , Metano/análise , Água , Áreas Alagadas
10.
Artigo em Inglês | MEDLINE | ID: mdl-35457290

RESUMO

Policies to mitigate climate change are essential. The objective of this paper was to estimate the impact of greenhouse gas (GHG) food taxes and assess whether such a tax could also have health benefits in Aotearoa NZ. We undertook a systemised review on GHG food taxes to inform four tax scenarios, including one combined with a subsidy. These scenarios were modelled to estimate lifetime impacts on quality-adjusted health years (QALY), health inequities by ethnicity, GHG emissions, health system costs and food costs to the individual. Twenty-eight modelling studies on food tax policies were identified. Taxes resulted in decreased consumption of the targeted foods (e.g., -15.4% in beef/ruminant consumption, N = 12 studies) and an average decrease of 8.3% in GHG emissions (N = 19 studies). The "GHG weighted tax on all foods" scenario had the largest health gains and costs savings (455,800 QALYs and NZD 8.8 billion), followed by the tax-fruit and vegetable subsidy scenario (410,400 QALYs and NZD 6.4 billion). All scenarios were associated with reduced GHG emissions and higher age standardised per capita QALYs for Maori. Applying taxes that target foods with high GHG emissions has the potential to be effective for reducing GHG emissions and to result in co-benefits for population health.


Assuntos
Gases de Efeito Estufa , Animais , Bovinos , Frutas/química , Efeito Estufa , Gases de Efeito Estufa/análise , Nova Zelândia , Impostos , Verduras
11.
Nutrients ; 14(7)2022 Apr 06.
Artigo em Inglês | MEDLINE | ID: mdl-35406132

RESUMO

Aimed at improving the quality of school meals, the Sustainable School Program (SSP) implemented low-carbon meals, twice a week, in 155 schools of 4 municipalities, reaching more than 32,000 students. This study evaluated the environmental impact and nutritional viability of this intervention for this population. The 15 most repeated meals from the conventional and sustainable menus were selected, and we considered the school age group and number of meals served per student/day. Nutritional information was calculated using validated food composition tables, nutritional adequacy was assessed using National School Feeding Program (PNAE) requirements, the level of processing was considered using NOVA classification, and greenhouse gas emissions (GHGE) were estimated using food life cycle assessment (LCA) validated data. We found both conventional and sustainable food menus are equivalent, in terms of nutrients, except for calcium, iron, and magnesium. Sustainable food menus were cholesterol-free. However, there was a reduction of up to 17% in GHGE, depending on the school age group analysed. Considering the greater energy efficiency and lower environmental impact of these food menus, the SSP, therefore, demonstrates that a substantial reduction in climate impact is feasible, successful, and can be an inspiration to other regions globally.


Assuntos
Serviços de Alimentação , Gases de Efeito Estufa , Brasil , Dieta , Meio Ambiente , Humanos , Refeições , Política Pública , Instituições Acadêmicas
12.
Environ Sci Technol ; 56(8): 5213-5223, 2022 Apr 19.
Artigo em Inglês | MEDLINE | ID: mdl-35377619

RESUMO

The climate crisis is urging us to act fast. Buildings are a key leverage point in reducing greenhouse gas (GHG) emissions, but the embodied emissions related to their construction often remain the hidden challenge of any ambitious policy. Therefore, in this paper, we explored material GHG neutralization where herbaceous biobased insulation materials with negative net-global warming potentials (GWPs) were used to compensate for building elements that necessarily release GHGs. Different material diets, as well as different building typologies, were modeled to assess the consequences in terms of biobased insulation requirements to reach climate neutrality. Our results show that climate-neutral construction can be built with sufficient energy performance to fulfill current standards and with building component thicknesses within a range of 1.05-0.58 m when timber- and bamboo-based construction is chosen. Concrete-based ones require insulation sizes that are too large and heavy to be supported by the dimensioned structures or accepted by urban regulations. Moreover, a time horizon of 20 years is more appropriate for assessing the contribution of material shifts to biobased materials in the transition period before 2050. This paper demonstrates that this is technically feasible and that climate neutrality in the construction sector just depends on the future that we choose.


Assuntos
Efeito Estufa , Gases de Efeito Estufa , Clima , Dieta , Aquecimento Global , Gases de Efeito Estufa/análise
13.
Nat Commun ; 13(1): 2095, 2022 Apr 19.
Artigo em Inglês | MEDLINE | ID: mdl-35440110

RESUMO

Battery-electric vehicles (BEV) have emerged as a favoured technology solution to mitigate transport greenhouse gas (GHG) emissions in many non-Annex 1 countries, including India. GHG mitigation potentials of electric 4-wheelers in India depend critically on when and where they are charged: 40% reduction in the north-eastern states and more than 15% increase in the eastern/western regions today, with higher overall GHGs emitted when charged overnight and in the summer. Self-charging gasoline-electric hybrids can lead to 33% GHG reductions, though they haven't been fully considered a mitigation option in India. Electric 2-wheelers can already enable a 20% reduction in GHG emissions given their small battery size and superior efficiency. India's electrification plan demands up to 125GWh of annual battery capacities by 2030, nearly 10% of projected worldwide productions. India requires a phased electrification with a near-term focus on 2-wheelers and a clear trajectory to phase-out coal-power for an organised mobility transition.


Assuntos
Gases de Efeito Estufa , Emissões de Veículos , Eletricidade , Gasolina/análise , Efeito Estufa , Gases de Efeito Estufa/análise , Veículos Automotores , Emissões de Veículos/análise
15.
Lancet Planet Health ; 6(4): e301-e309, 2022 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-35397218

RESUMO

BACKGROUND: Increasing air conditioner use for cooling indoor spaces has the potential to be a primary driver of global greenhouse gas emissions. Moving indoor air with residential fans can raise the temperature threshold at which air conditioning needs to be turned on to maintain the thermal comfort of building occupants. We investigate whether fans can be used to reduce air conditioner use and associated greenhouse gas emissions. METHODS: We developed an integrated framework, featuring a dynamic adaptive thermal comfort model with a geographical information system-based spatially gridded map of Australia, further complemented with census data. We assessed the change in energy use and associated greenhouse gas emissions for five scenarios of air conditioner and fan use: an air conditioner-only scenario (no fans); and four fan-first scenarios with fans operating at speeds of 0·1 m/s, 0·3 m/s, 0·8 m/s, and 1·2 m/s, with air conditioning used only once the upper temperature threshold for thermal discomfort is exceeded. For each day of the selected case study year, we estimated the upper temperature limit for thermal comfort and the number of hours in which air conditioning would be switched on. FINDINGS: The thermal comfort threshold was increased by the use of fans compared with air conditioner use alone. We found that widespread indoor fan use had the potential to reduce energy demand and greenhouse gas emissions attributable to air conditioner use, without compromising thermal comfort. Taking an annual perspective, the use of fans with air speeds of 1·2 m/s compared with air conditioner use alone resulted in a 76% reduction in energy use (from 5592 GWh to 1344 GWh) and associated greenhouse gas emissions (5091 kilotonnes to 1208 kilotonnes). INTERPRETATION: A common strategy to cope with hot weather is the use of air conditioners, which feed a cycle of high electricity consumption, often delivered by fossil fuel power stations that in turn contribute to further increases in emissions. Moving air with electric fans could serve as a sustainable alternative, reducing air conditioner use and associated greenhouse gas emissions without sacrificing thermal comfort. FUNDING: Australian Research Council, New South Wales Department of Planning, Industry and Environment, and The University of Sydney.


Assuntos
Gases de Efeito Estufa , Ar Condicionado , Austrália , Temperatura Baixa , Humanos , Temperatura
16.
J Environ Manage ; 312: 114925, 2022 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-35366512

RESUMO

To mitigate greenhouse gas emissions, China has committed to reducing its national carbon emission intensity, which is a measure of carbon dioxide produced per unit of gross domestic product (GDP), by 65% by 2030 compared with the level in 2005. The government is pursuing corresponding abatement initiatives to achieve this goal. Coupling the physical data of sectoral energy inputs and emissions with a mixed exogenous/endogenous input-output model, this study first projected the carbon emissions in 2030 under a business-as-usual baseline and then investigated the potential economic effects of the "command-and-control" approach for reducing carbon emissions by limiting production capacity and strengthening forest carbon sink management. Three carbon abatement scenarios were evaluated from the perspectives of social equity, abatement efficiency, and forest carbon sinks. Our results indicated that, under the 2030 carbon emission goal, the GDP in China would decline by 17.17-41.26 trillion yuan (equivalent to a marginal abatement cost of 2315-5387 yuan per ton of carbon dioxide reduction), depending on different policy initiatives. The policy of carbon reduction for high-emission sectors only is more cost-effective and economically efficient and has resulted in fewer negative economic impacts than the policy of requiring all economic sectors to do so. Asking high-carbon emission industries to undertake carbon abatement can further reduce national carbon emission intensity. Additionally, promoting forest carbon sinks as an abatement initiative also demonstrates substantial economic benefits for society.


Assuntos
Dióxido de Carbono , Gases de Efeito Estufa , Dióxido de Carbono/análise , China , Desenvolvimento Econômico , Objetivos , Gases de Efeito Estufa/análise , Indústrias , Políticas
17.
Environ Sci Technol ; 56(9): 5299-5301, 2022 May 03.
Artigo em Inglês | MEDLINE | ID: mdl-35416656
18.
J Environ Manage ; 313: 115002, 2022 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-35390658

RESUMO

Different environmental and social concerns can arise due to the generation of gaseous emissions during the treatment of urban wastewater. However, there is not an extensive knowledge about which are the main potential odour and greenhouse gas (GHG) emission sources in a wastewater treatment plant (WWTP) and their variability. In this study, a multipoint characterization of the gaseous emissions generated in a full-scale municipal WWTP located in Barcelona was conducted, aiming at identifying the main odour and GHG emission sources. The WWTP under study treats an average inlet flow of 33,000 m3 d-1 using a Ludzack-Ettinger system with Membrane BioReactor (MBR) technology, and it has installed a gas caption and treatment system consisting of a biotrickling filter followed by a conventional biofilter to treat part of the off-gases produced during the wastewater treatment. For this work, gaseous emissions characterization campaigns were conducted to assess the proper performance of the gas treatment unit and to estimate the emission factors referred to odorants and GHGs for the different emission sources and to assess the proper performance of the gas treatment system. Besides, a chemical characterization of the different volatile organic compounds (VOC) present in the gaseous emissions was performed through TD-GC/MS. The main potential odour sources were the reception tank, the barscreens building and the primary settler, where odour concentrations were in the range of 1300 and 2600 ou·m-3. Moreover, GHG emissions were found during the primary treatment and in the MBR units, ranging from 2.21 to 68,217.13 mg CO2eq·m-3. Different VOCs such as aromatic hydrocarbons, alkanes and ketones were found in the gaseous emissions with a high variability among all the emission sources. The results obtained are valuable indicators that can be used to develop odour and GHG mitigation strategies in WWTPs and to estimate the environmental impact of these facilities.


Assuntos
Gases de Efeito Estufa , Compostos Orgânicos Voláteis , Purificação da Água , Gases/análise , Odorantes/análise , Compostos Orgânicos Voláteis/análise , Águas Residuárias/análise
19.
Huan Jing Ke Xue ; 43(4): 2151-2162, 2022 Apr 08.
Artigo em Chinês | MEDLINE | ID: mdl-35393839

RESUMO

In recent years, carbon emission research has been receiving increasing attention. China has put forward the strategic goal of achieving a carbon emission peak by 2030. Hence this research is very important for the measurement of greenhouse gas emissions in China. CO2 and CH4 fluxes from a paddy field in the middle-lower Yangtze Plain in China were analyzed based on the eddy covariance technique. The CO2 flux showed an "U" curve during the observation period, with an average flux of -3.33 µmol·(m2·s)-1, which was a sink. Negative values appeared at the tillering stage, and the minimum was shown at the heading period. The CH4 flux trend was roughly opposite to the that of the CO2 flux, which first increased and then decreased. It raised rapidly during the tillering and jointing stages and then dropped rapidly from the peak to the trough during the booting stage, and only a slight increase was found in the blooming stage. The maximum flux[0.40 µmol·(m2·s)-1] appeared at the beginning of the booting stage and the end of the jointing stage, and the average flux was 0.11 µmol·(m2·s)-1. The CO2 flux was positive at night and negative during the day. It decreased from 07:00 and reached a minimum around 13:00 at -16.01 µmol·(m2·s)-1. The CH4 flux was low at night and high during the daytime. It increased at 06:00 and reached a peak around 14:00, at approximately 0.16 µmol·(m2·s)-1. An exponential correlation was found between air temperature and CH4 flux. The vapor pressure deficit showed a linear correlation with CH4 flux. The response of environmental factors on CO2 fluxes and CH4 fluxes on a diurnal scale was greater than that on a seasonal scale, and the daytime response was greater than that at night. CH4 flux decreased significantly with the increase in CO2 flux on the diurnal scale, but the correlation was not obvious on the seasonal scale. The increased CH4 flux slowed down after fertilizing.


Assuntos
Gases de Efeito Estufa , Carbono , Dióxido de Carbono/análise , China , Gases de Efeito Estufa/análise , Metano/análise , Óxido Nitroso/análise , Estações do Ano
20.
Huan Jing Ke Xue ; 43(4): 2171-2181, 2022 Apr 08.
Artigo em Chinês | MEDLINE | ID: mdl-35393841

RESUMO

Methane (CH4) and nitrous oxide (N2O) are two extremely important greenhouse gases in the atmosphere. Nitrogen fertilizer is an important factor affecting CH4 and N2O emissions in rice fields. Rational application of nitrogen fertilizer can not only promote high yields of rice but also reduce greenhouse gas emissions. Existing studies have shown that nitrogen reduction and optimal application can effectively improve the nitrogen use efficiency of rice on the basis of ensuring the yield and reduce the loss of N2O caused by nitrification and denitrification of excessive nitrogen in soil. Fertilization times and fertilizer types have significant effects on CH4 and N2O emissions in paddy fields. In this study, a field experiment was conducted for two consecutive years (2019-2020) to study the effects of fertilizer application on CH4 and N2O emissions from rice fields by setting up four treatments consisting of no fertilizer (CK), customary fertilizer application by farmers (CF), twice fertilizer (TT), and 20% replacement of chemical fertilizer by organic fertilizer (OF) using static chamber-gas chromatography. Additionally, the effect of integrating rice yield and integrated global warming potential (GWP) on the greenhouse gas emission intensity (GHGI) per unit of rice yield was analyzed to explore fertilizer application for yield increase and emission reduction in a typical rice growing area in the middle and lower reaches of Yangtze River. The results showed that:① compared with those of CK, the fertilizer treatments reduced CH4 emissions by 14.6%-25.1% and increased N2O emissions by 610%-1836% in both years; ② compared with those of CF, both the TT and OF treatments showed a trend of increasing CH4 emissions and reducing N2O emissions. CH4 emissions increased by 1.8% (P>0.05) and 14.0% (P<0.05), respectively. The annual average of N2O emissions decreased by 63.3% (P<0.05) and 49.2% (P<0.05) in both the TT and OF treatments, respectively. ③ Compared with that of CK, both fertilizer applications increased rice yield and reduced GHGI; compared with that of CF, the OF and TT treatments increased the average annual rice yield by 17.0% and 10.7%, respectively, and reduced GHGI by 6.8% and 13.7%, respectively. The OF treatment had a better yield increase than that of the TT treatment, and the TT treatment had a slightly better emission reduction than that of the OF treatment. In terms of combined yield and GHG emission reduction, both twice fertilizer (TT) and 20% replacement of chemical fertilizer by organic fertilizer (OF) could reduce the intensity of GHG emission per unit of rice yield and achieve yield increase and emission reduction while ensuring rice yield.


Assuntos
Gases de Efeito Estufa , Oryza , Agricultura/métodos , Fertilizantes/análise , Gases de Efeito Estufa/análise , Metano/análise , Nitrogênio/análise , Óxido Nitroso/análise , Solo/química
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