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1.
J Environ Manage ; 289: 112486, 2021 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-33831757

RESUMO

Climate change is a global issue threatening agricultural production and human survival. However, agriculture sector is a major source of global greenhouse gases (GHGs), especially CH4 and N2O. Crop residue returning (RR) is an efficient practice to sequestrate soil carbon and increase crop yields. However, the efficiency of RR to mitigate climate change and maintain food security will be affected by the response of GHG emissions at both per area-scale and per yield-scale. Therefore, a national meta-analysis was conducted using 309 comparisons from 44 publications to assess the responses of GHG emissions to RR in China's croplands. The results indicated that little response of GWP to RR was observed with conditions under lower nitrogen fertilizer input rates (0-120 kg ha-1), mulch retention, returning one time in double cropping systems, returning with half residue, weakly acidic soil (pH 5.5-6.5), initial SOC contents >20 g kg-1, or mean annual precipitation <1000 mm. In order to mitigate climate change and sustain food security, RR combined with paddy-upland rotation, nitrogen fertilizer input rates of 240-360 kg ha-1, and neutral soil (pH 6.5-7.5) could decrease GWP at per unit of crop yield, which ultimately leads to a lower effect on GHGI and a higher crop production efficiency. In-depth studies should be conducted in the future to explore the interactions between various factors influencing GHG emissions under RR conditions. Overall, optimizing the interactions with management and site-specific conditions, potential for regulating GHGs emissions of RR can be enhanced.


Assuntos
Gases de Efeito Estufa , Oryza , Agricultura , China , Produtos Agrícolas , Aquecimento Global , Efeito Estufa , Gases de Efeito Estufa/análise , Humanos , Metano/análise , Óxido Nitroso/análise , Solo
2.
J Environ Manage ; 289: 112526, 2021 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-33848879

RESUMO

Methane (CH4) is a prominent Greenhouse Gas (GHG) and its global atmospheric concentration has increased significantly since the year 2007. Anthropogenic CH4 emissions are projected to be 9390 million metric tonnes by 2020. Here, we present the long-term changes in atmospheric methane over India and suggest possible alternatives to reduce soil emissions from paddy fields. The increase in atmospheric CH4 concentrations from 2009 to 2020 in India is significant, about 0.0765 ppm/decade. The Indo-Gangetic Plains, Peninsular India and Central India show about 0.075, 0.076 and 0.074 ppm/decade, respectively, in 2009-2020. Seasonal variations in CH4 emissions depend mostly on agricultural activities and meteorology, and contribution during the agricultural intensive period of Kharif-Rabi (i.e., June-December) is substantial in this regard. The primary reason for agricultural soil emissions is the application of chemical fertilizers to improve crop yield. However, for rice farming, soil amendments involving stable forms of carbon can reduce GHG emissions and improve soil carbon status. High crop production in pot culture experiment resulted in lower potential yield-scaled GHG emissions in rice with biochar supplement. The human impact of global warming induced by agricultural activities could be reduced by using biochar as a natural solution.


Assuntos
Gases de Efeito Estufa , Oryza , Agricultura , Fertilizantes/análise , Aquecimento Global , Gases de Efeito Estufa/análise , Humanos , Índia , Metano/análise , Óxido Nitroso/análise , Solo
3.
Ying Yong Sheng Tai Xue Bao ; 32(2): 581-590, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33650368

RESUMO

Studying the effects of rainfall regimes such as rainfall amount and timing on soil carbon mineralization is of great importance for our understanding the mechanisms underlying the stability and accumulation of soil carbon in coastal salt marshes. In this study, we examined the responses of soil carbon mineralization (CO2 and CH4 fluxes) from undisturbed soil columns to rainfall events in different seasons (dry and wet seasons) with filed experiments in a primary Suaeda salsa region in the Yellow River Delta salt-marsh wetland, which is far away from the coast and not affected by tides. The results showed that rainfall amount and timing had a significant interaction in affecting soil CO2 flux rates. During the dry season, large rainfall events significantly reduced soil CO2 flux rates but had no significant effect in the wet season, which might be closely related to the significant increase in soil water content and salinity. Rainfall amount, rainfall timing and their interactions had no significant effect on soil CH4 efflux rates. Rainfall timing and rainfall amount did not affect CH4/CO2. CH4/CO2 increased with increasing soil water content and salinity. Soil water content and soil salinity showed similar increases to increasing rainfall amount. Our results suggested that the changing rainfall regime under climate change in the future would have a great impact on soil carbon mineralization and carbon sink function by regulating soil water and salt migration in this region.


Assuntos
Solo , Áreas Alagadas , Carbono/análise , Dióxido de Carbono/análise , China , Metano/análise , Rios
4.
J Emerg Manag ; 19(1): 93-100, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33735439

RESUMO

Natural gas well blowouts can release a large amount of methane along with other greenhouse gases. According to the Intergovernmental Panel on Climate Change, the global warming potential (GWP) of fossil methane is 30 times higher than that of carbon dioxide in a 100-year time horizon. Here, we show that combustion can be used as a means to significantly reduce the global warming effect of greenhouse emissions from gas well blowouts: up to 90 percent of the effect can be eliminated by combusting the released natural gas. The 2015 Aliso Canyon storage well blowout is used as an example.


Assuntos
Gases de Efeito Estufa , Efeito Estufa , Humanos , Metano/análise , Gás Natural , Campos de Petróleo e Gás
5.
J Environ Manage ; 288: 112363, 2021 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-33756388

RESUMO

This study evaluated the effects of thermal pretreatment of brewery spent grain (BSG) (by autoclave 121 °C, 1.45 atm for 30 min) on methane production (CH4). Operation temperature (31-59 °C) and substrate concentration (8.3-19.7 g BSG.L-1) factors were investigated by Response Surface Methodology (RSM) and Central Composite Design (CCD). Values ranging from 81.1 ± 2.0 to 290.1 ± 3.5 mL CH4.g-1 TVS were obtained according to operation temperature and substrate concentration variation. The most adverse condition for methanogenesis (81.1 ± 2.0 mL CH4.g-1 TVS) was at 59 °C and 14 g BSG.L-1, in which there was increase in the organic matter concentration from 173.6 ± 4.94 to 3036 ± 7.78 mg.L-1) result of a higher final concentration of volatile fatty acids (VFA, 2662.7 mg.L-1). On the other hand, the optimum condition predicted by the statistical model was at 35 °C and 18 g BSG.L-1 (289.1 mL CH4.g-1 TVS), which showed decrease in the organic matter concentration of 78.6% and a lower final concentration of VFA (533.2 mg.L-1). Hydrogenospora and Methanosaeta were identified in this optimum CH4 production condition, where acetoclastic methanogenic pathway prevailed. The CH4 production enhancement was concomitant to acetic acid concentration decrease (from 578.9 to 135.7 mg.L-1).


Assuntos
Euryarchaeota , Metano , Anaerobiose , Reatores Biológicos , Grão Comestível , Ácidos Graxos Voláteis , Metano/análise , Temperatura
6.
Water Res ; 194: 116958, 2021 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-33662685

RESUMO

Methane (CH4) and nitrous oxide (N2O) are the most powerful greenhouse gases globally; recent emissions exceed previous estimates. The potential link between N2O reduction and CH4 oxidation in anoxic wetland sediments would be a sink for both gases, which has attracted broad attention. To explore the simultaneous N2O and CH4 biotransformation, wetland sediments were used to inoculate an enrichment reactor, continuously fed with CH4 and N2O for 500 days. After enrichment, the CH4 oxidation rate reached 2.8 µmol·g-1dw·d-1, which was 800-fold higher than the rate of the wetland sediments used as inoculum. Moreover, stable isotopic tracing proved CH4 oxidation was driven by N2O consumption under anoxic conditions. Genomic sequencing showed that the microbial community was dominated by methanotrophs. Species of Methylocaldum genus, belonging to γ-Proteobacteria class, were significantly enriched, and became the predominant methanotrophs. Quantitative analysis indicated methane monooxygenase and nitrous oxide reductase increased by 38- and 8-fold compared to the inoculum. As to the potential mechanisms, we propose that N2O-driven CH4 oxidation was mediated by aerobic methanotrophs solely or along with denitrifying bacteria under hypoxia. Electrons and energy are generated and transferred in the oxidative phosphorylation pathway. Our findings expand the range of electron acceptors associated with CH4 oxidation as well as elucidate the significant role of methanotrophs relative to both carbon and nitrogen cycles.


Assuntos
Gases de Efeito Estufa , Óxido Nitroso , Humanos , Hipóxia , Metano/análise , Óxido Nitroso/análise , Áreas Alagadas
7.
Waste Manag ; 124: 368-376, 2021 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-33662768

RESUMO

Many methods have been applied to monitor fugitive methane gas from landfills. Recently, there have been suggestions to use a framework utilizing an unmanned aerial vehicle (UAV) for landfill gas monitoring, and several field campaigns have proved that a rotary UAV-based measurement has advantages of ease of control and high-resolution concentration mapping on the target planes. However, research on the evaluation of error-inducing factors in the suggested system is limited so far. This study prepared a measurement system with a lightweight methane detector and a rotary UAV to support the applicability of rotary UAV in landfill gas monitoring. Then, the validity of the system was tested experimentally and theoretically. In the detector reliability test, the methane detector had sufficient resolution for field application. The critical UAV velocity required was obtained to ensure the credibility of the proposed measurement system. When spatial interpolators were applied to field data from the measurement system, the empirical Bayesian kriging demonstrated the best prediction of methane concentrations at unmeasured points. With the verifications provided in this study, this proposed method may contribute to reducing uncertainty in estimating fugitive landfill gas emission.


Assuntos
Poluentes Atmosféricos , Eliminação de Resíduos , Poluentes Atmosféricos/análise , Teorema de Bayes , Monitoramento Ambiental , Metano/análise , Reprodutibilidade dos Testes , Resíduos Sólidos , Instalações de Eliminação de Resíduos
8.
Water Res ; 196: 116985, 2021 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-33735621

RESUMO

Lakes are important sources of greenhouse gases (GHGs) to the atmosphere. Factors controlling CO2, CH4 and N2O fluxes include eutrophication and warming, but the integrated influence of climate-warming-driven stratification, oxygen loss and resultant changes in bloom characteristics on GHGs are not well understood. Here we assessed the influence of contrasting meteorological conditions on stratification and phytoplankton bloom composition in a eutrophic lake, and tested for associated changes in GHGs inventories in both the shallow and deep waters, over three seasons (2010-2012). Atmospheric heatwaves had one of the most dramatic effects on GHGs. Indeed, cyanobacterial blooms that developed in response to heatwave events in 2012 enhanced both sedimentary CH4 concentrations (reaching up to 1mM) and emissions to the atmosphere (up to 8 mmol m-2 d-1). That summer, CH4 contributed 52% of the integrated warming potential of GHGs produced in the lake (in CO2 equivalents) as compared to between 34 and 39% in years without cyanobacterial blooms. High CH4 accumulation and subsequent emission in 2012 were preceded by CO2 and N2O consumption and under-saturation at the lake surface (uptakes at -30 mmol m-2 d-1 and -1.6 µmol m-2 d-1, respectively). Fall overturn presented a large efflux of N2O and CH4, particularly from the littoral zone after the cyanobacterial bloom. We provide evidence that, despite cooling observed at depth during hot summers, CH4 emissions increased via stronger stratification and surface warming, resulting in enhanced cyanobacterial biomass deposition and intensified bottom water anoxia. Our results, supported by recent literature reports, suggests a novel interplay between climate change effects on lake hydrodynamics that impacts both bloom characteristics and GHGs production in shallow eutrophic lakes. Given global trends of warming and enrichment, these interactive effects should be considered to more accurately predict the future global role of lakes in GHG emissions.


Assuntos
Gases de Efeito Estufa , Lagos , Dióxido de Carbono/análise , China , Lagos/análise , Metano/análise , Fitoplâncton
9.
J Environ Manage ; 287: 112334, 2021 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-33735676

RESUMO

Livestock production is the major livelihood for a growing local population on the Tibetan plateau. However, government policy is to reduce the number of livestock due to the large quantities of greenhouse gasses (GHG), in particular methane, produced by ruminants and the degradation of the grasslands. For this policy to be effective, with little effect on livelihoods, there should be a decoupling of GHG emissions from economic growth of livestock products. This study examined the synergetic effects of policies, extreme climate events and GHG emissions from livestock at the headwater region of the Yellow River since 1980. Optimization models of GHG emissions efficiency and drivers were developed and parameterized. Trade-offs between GHG emissions from livestock and economic growth from livestock, determined by the decoupling model, showed that from 1980 to 2015: 1) the GHG emissions decreased by 39%; (2) CH4 emissions from livestock decreased by 33%, and yaks emitted the most (accounted for 99.6%) among livestock; (3) N2O emissions decreased by 34%; (4) trade-offs between livestock GHG emissions and grassland uptake indicated that the grazing livestock system functioned as a net carbon sink; (5) the efficiency factor, especially technical efficiency, was the main driver of GHG emissions; and (6) GHG emissions from livestock were in a decoupling state from economic growth from livestock. However, decoupling has not been stable as inter-annual fluctuations have been large mainly due to extreme climatic events, such as snowstorm disasters, which indicates that the grazing system was still relatively fragile. The GHG emissions can be reduced further by mitigating CH4 emissions, and enhancing CO2 sequestration on grazed pastureland. The ongoing transformation of livestock industry development on the Tibetan plateau is associated with uncertainty under the background of global GHG mitigation.


Assuntos
Gases de Efeito Estufa , Animais , Desenvolvimento Econômico , Efeito Estufa , Gases de Efeito Estufa/análise , Gado , Metano/análise , Óxido Nitroso/análise , Tibet
10.
Water Res ; 196: 117056, 2021 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-33774352

RESUMO

The impact of cultural eutrophication on carbon cycling in subtropical reservoirs was assessed using high-resolution measurements of dissolved gas concentration, atmospheric exchange, and uptake/production rates of methane, carbon dioxide, and oxygen. Seasonal measurements were performed in two reservoirs that pertain to the same hydrological basin but are drastically different in terms of allochthonous carbon input. These results were used to feed a mass balance model, from which a large number of overall parameters were determined to explicitly describe the dynamics and spatial attributes of the carbon cycle in the reservoirs. A single graphical representation of each reservoir was created to facilitate an overall appraisal of the carbon cycle. The impact of cultural eutrophication was profound and resulted in a complete redistribution of how the various bioprocesses participated in the methane, carbon dioxide, and oxygen cycles. Among several identified impacts of eutrophication, it was observed that while eutrophication triggered increased methane production, this effect was followed by a similar increase in methane emissions and methanotrophic rates, while gross primary production was depleted.


Assuntos
Gases de Efeito Estufa , Dióxido de Carbono/análise , Monitoramento Ambiental , Eutrofização , Gases de Efeito Estufa/análise , Metano/análise , Oxigênio
11.
Bioresour Technol ; 330: 124952, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-33744739

RESUMO

This research investigates the treatment efficiency and greenhouse gas (GHG) emissions of non-floating and floating bed AS systems with acclimatized sludge treating landfill leachate. The GHGs under study included carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O). The non-floating and floating bed AS systems were operated in parallel with identical landfill leachate influent under different hydraulic retention time (HRT) conditions (24, 18, and 12 h). The experimental results showed that the treatment efficiency of organic compounds under 24 h HRT of both systems (90 - 98%) were insignificantly different, while the nutrient removal efficiency of both systems were between 54 and 98 %. The treatment efficiency of the floating bed AS system, despite shorter HRT, remained relatively unchanged due to an abundance of effective bacteria residing in the floating media. The CO2 emissions were insignificantly different between both AS systems under all HRT conditions (22 - 26.3 µmol/cm2.min). The CO2 emissions were positively correlated with organic loading but inversely correlated with HRT. The CH4 emissions were positively correlated with HRT (26.3 µmol/cm2.min under 24 h HRT of the floating bed AS system). The N2O emissions were positively correlated with nitrogen loading, and the N2O emissions from the floating bed AS system were lower due to an abundance of N2O-reducing bacteria. The floating media enhanced the biological treatment efficiency while maintaining the bacterial community in the system. However, the floating media promoted CH4 production under anoxic conditions. The originality of this research lies in the use of floating media in the biological treatment system to mitigate GHG emissions, unlike existing research which focused primarily on enhancement of the treatment efficiency.


Assuntos
Gases de Efeito Estufa , Poluentes Químicos da Água , Dióxido de Carbono/análise , Efeito Estufa , Metano/análise , Óxido Nitroso/análise , Esgotos , Poluentes Químicos da Água/análise
12.
Environ Sci Technol ; 55(8): 4462-4473, 2021 04 20.
Artigo em Inglês | MEDLINE | ID: mdl-33759511

RESUMO

Nitrous oxide (N2O) is a long-lived greenhouse gas that also destroys stratospheric ozone. N2O emissions are uncertain and characterized by high spatiotemporal variability, making individual observations difficult to upscale, especially in mixed land use source regions like the San Joaquin Valley (SJV) of California. Here, we calculate spatially integrated N2O emission rates using nocturnal and convective boundary-layer budgeting methods. We utilize vertical profile measurements from the NASA DISCOVER-AQ (Deriving Information on Surface Conditions from COlumn and VERtically Resolved Observations Relevant to Air Quality) campaign, which took place January-February, 2013. For empirical constraints on N2O source identity, we analyze N2O enhancement ratios with methane, ammonia, carbon dioxide, and carbon monoxide separately in the nocturnal boundary layer, nocturnal residual layer, and convective boundary layer. We find that an established inventory (EDGAR v4.3.2) underestimates N2O emissions by at least a factor of 2.5, that wintertime emissions from animal agriculture are important to annual totals, and that there is evidence for higher N2O emissions during the daytime than at night.


Assuntos
Poluentes Atmosféricos , Óxido Nitroso , Agricultura , Poluentes Atmosféricos/análise , Aeronaves , Animais , California , Metano/análise , Óxido Nitroso/análise
13.
Environ Sci Technol ; 55(8): 4532-4541, 2021 04 20.
Artigo em Inglês | MEDLINE | ID: mdl-33788543

RESUMO

Nitrogen oxides (NOX) and methane impact air quality through the promotion of ozone formation, and methane is also a strong greenhouse gas. Despite the importance of these pollutants, emissions in urban areas are poorly quantified. We present measurements of NOX, CH4, CO, and CO2 made at Drexel University in Philadelphia along with NOX and CO observations at two roadside monitors. Because CO2 concentrations in the winter result almost entirely from combustion with negligible influence from photosynthesis and respiration, we are able to infer fleet-averaged fuel-based emission factors (EFs) for NOX and CO, similar in some ways to how EFs are determined from tunnel studies. Comparison of the inferred NOX and CO fuel-based EF to the National Emissions Inventory (NEI) suggests errors in NEI emissions of either NOX, CO, or both. From the measurements of CH4 and CO2, which are not emitted by the same sources, we infer the ratio of CH4 emissions (from leaks in the natural gas infrastructure) to CO2 emissions (from fossil fuel combustion) in Philadelphia. Comparison of the CH4/CO2 emission ratios to emission inventories from the Environmental Protection Agency suggests underestimates in CH4 emissions by almost a factor of 4. These results demonstrate the need for the addition of long-term observations of CH4 and CO2 to existing monitoring networks in urban areas to better constrain emissions and complement existing measurements of NOX and CO.


Assuntos
Poluentes Atmosféricos , Monóxido de Carbono , Poluentes Atmosféricos/análise , Dióxido de Carbono/análise , Monóxido de Carbono/análise , Monitoramento Ambiental , Humanos , Metano/análise , Óxidos de Nitrogênio/análise , Philadelphia
14.
Environ Sci Technol ; 55(8): 4183-4189, 2021 04 20.
Artigo em Inglês | MEDLINE | ID: mdl-33666422

RESUMO

Energy supply limits development through fuel constraints and climatic effects. Production of renewable energy is a central pillar of sustainability but will need to play an increasingly important role in energy generation in order to mitigate fossil-fuel based greenhouse-gas emissions. Global freshwaters represent a vast reservoir of biomass and biogenic CH4. Here we demonstrate the great potential for the optimized use of this nonfossil carbon as a source of energy that is replenishable within a human lifetime. The feasibility of up-scaled adsorption-driven technologies to capture and refine aqueous CH4 still awaits verification, yet recent estimates of global freshwater CH4 production imply that the worldwide energy demand could be satisfied by using the "biofuel" building up in lakes and wetlands. Biogenic CH4 is mostly generated from biomass produced through atmospheric CO2 uptake. Its exploitation in freshwaters can thus secure large amounts of carbon-neutral energy, helping to sustain the planetary equilibrium.


Assuntos
Gases de Efeito Estufa , Metano , Dióxido de Carbono/análise , Combustíveis Fósseis , Água Doce , Humanos , Metano/análise , Áreas Alagadas
15.
Environ Pollut ; 276: 116696, 2021 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-33744496

RESUMO

It is a common practice to maintain soil fertility based on the paddy-upland rotation with green manure in the subtropical region of China. However, rare studies are known about greenhouse gas (GHG) emissions from the paddy-upland rotation with green manure incorporation. Therefore, we conducted a field experiment of two years to compared with the effect of two kinds of green manure (CV: Chinese milk vetch and OR: Oilseed rape), and two kinds of cropping system (DR: double rice system and PR: paddy-upland rotation) on greenhouse gases emissions. We have found that the annual accumulation of CH4 of Chinese milk vetch-rice-sweet potato || soybean was significantly reduced by 32.95%∼63.22% compared with other treatments, mainly because Chinese milk vetch reduced the abundance of methanogens by reducing soil C/N ratio. Meanwhile increasing soil permeability resulting from paddy-upland rotation also reduced soil CH4 emission. However, The annual accumulation of N2O of Chinese milk vetch-rice-sweet potato || soybean was increased by 17.39%∼870.11% compared with other treatments, mainly attributed to paddy-upland rotation decreased soil pH and nosZ abundance and increased nirK and nirS, thus enhancing N2O emission, meanwhile the Chinese milk vetch incorporation and its interaction with the paddy-upland rotation has greatly enhanced the contents of NO3--N and abundance of ammonia-oxidizing archaea (AOA). The area-scaled global warming potential (GWP) and the biomass-scaled greenhouse gas emissions intensity (GHGI) of Chinese milk vetch-rice-sweet potato || soybean was reduced by 19.01%∼50.69% and 5.38%∼35.77% respectively. Thereby, the Chinese milk vetch-rice-sweet potato || soybean cropping system was suitable for agricultural sustainable development.


Assuntos
Astrágalo (Planta) , Gases de Efeito Estufa , Oryza , Agricultura , China , Aquecimento Global , Metano/análise , Óxido Nitroso/análise , Rotação , Solo
16.
Ying Yong Sheng Tai Xue Bao ; 32(3): 942-950, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33754560

RESUMO

The strategy of few or no-phosphorus fertilization in rice season but more in wheat season can effectively increase phosphorus use efficiency and reduce phosphorus loss through runoff and leaching. It remains unknown whether the lack of phosphorus will affect greenhouse gas emission in the rice season. We monitored the CH4 and N2O emission fluxes during the growth period of rice treated with normal phosphorus application (NPK) and no-phosphorus application (NK) in two long-term experimental fields in Suzhou and Yixing. The results showed that long-term no-phosphorus application promoted CH4 and N2O emission in both fields. Compared with the NPK treatment, CH4 and N2O emissions from the NK treatment significantly increased by 57% and 25% in Suzhou experi-mental field, respectively, while those in Yixing experimental field were also significantly increased by 221% and 70%, respectively. The contents of organic acid, dissolved organic carbon and available phosphorus in soil were reduced under long-term NK treatment, and they were closely related to CH4 emission. Soil available phosphorus content was significantly negatively correlated with CH4 emission (r=-0.987). The global warming potential (GWP) was greater in NK treatment than NPK treatment in both fields. Therefore, long-term no-phosphorus application could decrease the contents of organic acid, soluble organic carbon, and available phosphorus in soils, resulting in more CH4 and N2O emission in rice field.


Assuntos
Gases de Efeito Estufa , Oryza , Agricultura , China , Fertilização , Fertilizantes , Gases de Efeito Estufa/análise , Metano/análise , Óxido Nitroso/análise , Fósforo , Solo
17.
Waste Manag Res ; 39(3): 508-515, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33583354

RESUMO

This study evaluated the performance of a plug-flow reactor (PFR) for high-rate anaerobic co-digestion of complex agro-industrial wastes and used cooking oil or animal fat. The PFR was successfully operated up to an organic loading rate (OLR) of 21 g L-1 d-1, yielding biogas at 0.35 L g-1 chemical oxygen demand (COD) influent. During the study period, supernatant COD at the PFR effluent remained between 4 and 7 g L-1, with negligible volatile fatty acids' concentrations (<500 mg L-1) and no presence of foaming incidents. The biomass concentration inside the PFR, expressed as total suspended solids, remained between 30 and 60 g L-1. Moreover, the above-mentioned anaerobic digestion technology has been currently scaled-up at 50 m3 PFR, while a full-scale facility of 240 kW-el is under construction in the region of north-eastern Greece.


Assuntos
Reatores Biológicos , Resíduos Industriais , Anaerobiose , Animais , Análise da Demanda Biológica de Oxigênio , Grécia , Metano/análise , Eliminação de Resíduos Líquidos
18.
Nat Commun ; 12(1): 1101, 2021 02 17.
Artigo em Inglês | MEDLINE | ID: mdl-33597520

RESUMO

It is widely hypothesised that primeval life utilised small organic molecules as sources of carbon and energy. However, the presence of such primordial ingredients in early Earth habitats has not yet been demonstrated. Here we report the existence of indigenous organic molecules and gases in primary fluid inclusions in c. 3.5-billion-year-old barites (Dresser Formation, Pilbara Craton, Western Australia). The compounds identified (e.g., H2S, COS, CS2, CH4, acetic acid, organic (poly-)sulfanes, thiols) may have formed important substrates for purported ancestral sulfur and methanogenic metabolisms. They also include stable building blocks of methyl thioacetate (methanethiol, acetic acid) - a putative key agent in primordial energy metabolism and thus the emergence of life. Delivered by hydrothermal fluids, some of these compounds may have fuelled microbial communities associated with the barite deposits. Our findings demonstrate that early Archaean hydrothermal fluids contained essential primordial ingredients that provided fertile substrates for earliest life on our planet.


Assuntos
Archaea/química , Sulfeto de Hidrogênio/análise , Metano/análise , Compostos de Sulfidrila/análise , Sulfato de Bário/análise , Planeta Terra , Ecossistema , Microbiologia Ambiental , Evolução Química , Cromatografia Gasosa-Espectrometria de Massas , Geografia , Sedimentos Geológicos/química , Fatores de Tempo , Austrália Ocidental
19.
Waste Manag ; 123: 52-59, 2021 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-33561770

RESUMO

A mixture of supermarket food waste from bakery, butchery, cooked meats and cheese, fishmonger, fruit, and vegetable sections was subjected to anaerobic digestion under thermophilic conditions (55 °C). Lab-scale induced bed reactors (IBR) and completely stirred tank reactors (CSTR) were operated at different organic loading rates (OLR), i.e., 3.0, 3.6 and 4.6 kg volatile solids (VS) per m3 of reactor and day. Regardless of the type of reactor, an OLR of 3.6 kg VS/m3·day was found to be the optimum, achieving up to 48.1% more methane production per kg of treated waste than for the other OLRs tested. In general, there were no statistically significant differences (p-value < 0.05) between IBR and CSTR performance at the same OLR tested. However, for the optimum OLR, the IBR achieved a mean methane production of 1.5 L CH4/Lreactor·day (426.7 L CH4/kg VS) and the highest VS removal (89.0%, on average). This reactor obtained 22.1% more CH4 yield than the analogous CSTR and the highest methane content in the biogas (66.9% CH4). Finally, the process was successfully tested under large-scale conditions (1.25 m3 IBR pilot-plant). The CH4 production and the biodegradation yield were in line with those obtained in the lab-scale IBR.


Assuntos
Reatores Biológicos , Eliminação de Resíduos , Anaerobiose , Metano/análise
20.
Water Res ; 193: 116858, 2021 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-33540345

RESUMO

Due to regular influx of organic matter and nutrients, waste stabilization ponds (WSPs) can release considerable quantities of greenhouse gases (GHGs). To investigate the spatiotemporal variations of GHG emissions from WSPs with a focus on the effects of sludge accumulation and distribution, we conducted a bathymetry survey and two sampling campaigns in Ucubamba WSP (Cuenca, Ecuador). The results indicated that spatial variation of GHG emissions was strongly dependent on sludge distribution. Thick sludge layers in aerated ponds and facultative ponds caused substantial CO2 and CH4 emissions which accounted for 21.3% and 78.7% of the total emissions from the plant. Conversely, the prevalence of anoxic conditions stimulated the N2O consumption via complete denitrification leading to a net uptake from the atmosphere, i.e. up to 1.4±0.2 mg-N m-2 d-1. Double emission rates of CO2 were found in the facultative and maturation ponds during the day compared to night-time emissions, indicating the important role of algal respiration, while no diel variation of the CH4 and N2O emissions was found. Despite the uptake of N2O, the total GHG emissions of the WSP was higher than constructed wetlands and conventional centralized wastewater treatment facilities. Hence, it is recommended that sludge management with proper desludging regulation should be included as an important mitigation measure to reduce the carbon footprint of pond treatment facilities.


Assuntos
Gases de Efeito Estufa , Dióxido de Carbono/análise , Equador , Monitoramento Ambiental , Efeito Estufa , Gases de Efeito Estufa/análise , Metano/análise , Óxido Nitroso/análise , Tanques , Esgotos
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