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1.
Am J Gastroenterol ; 115(2): 165-178, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-32023228

RESUMO

Small intestinal bacterial overgrowth is defined as the presence of excessive numbers of bacteria in the small bowel, causing gastrointestinal symptoms. This guideline statement evaluates criteria for diagnosis, defines the optimal methods for diagnostic testing, and summarizes treatment options for small intestinal bacterial overgrowth. This guideline provides an evidence-based evaluation of the literature through the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) process. In instances where the available evidence was not appropriate for a formal GRADE recommendation, key concepts were developed using expert consensus.


Assuntos
Antibacterianos/uso terapêutico , Síndrome da Alça Cega/diagnóstico , Síndrome da Alça Cega/terapia , Dietoterapia , Transplante de Microbiota Fecal , Probióticos/uso terapêutico , Testes Respiratórios , Técnicas de Cultura , Humanos , Hidrogênio/análise , Intestino Delgado , Metano/análise , Sucção
2.
Sci Total Environ ; 714: 136738, 2020 Apr 20.
Artigo em Inglês | MEDLINE | ID: mdl-31982753

RESUMO

Despite the importance of atmospheric methane as a potent greenhouse gas and the significant contribution from ruminant enteric fermentation on methane emissions at a global scale, little effort has been made to consider the influence that different plant-based natural diets have on methane emissions in grazing systems. Heathland is an ericaceous dwarf-shrub-dominated habitat widespread across the northern hemisphere, in Europe, provides valuable ecosystem services in areas with poor soils, such as water flow regulation, land-based carbon skin, energy reservoir and habitat of key game species. We (i) measured methane emissions from red deer (Cervus elaphus) and sheep (Ovis aries) fed mixed diets of natural grass plus ericaceous species (either Calluna vulgaris or Vaccinium myrtillus) using open-circuit respiration chambers; and (ii) modelled the results to estimate methane emissions from red deer and sheep populations inhabiting heathland habitats across Europe under different scenarios of grass-based mixed diets with varying proportions of ericaceous species. Our results indicated that methane emissions per unit of digestible organic matter intake decreased as the proportion of ericaceous species in diet increased, but this relationship was complex because of the significant interaction between the proportion of ericaceous species in the diet and digestible organic matter intake. According to our estimates red deer and sheep populations across European heathlands produce 129.7 kt·y-1 methane (se = 1.79) based on a hypothetical grass-ericaceous species mixed diet containing 30% of ericaceous species; this is 0.5% of total methane emissions from human activity across Europe (24,755 kt·y-1), and a reduction in methane emissions of 63.8 kt·y-1 against the same deer and sheep populations, if assumed to consume a grass-only diet. We suggest the implementation of carbon credits as a measure to value the relevance of heathland systems to promote biodiversity and its potential contribution to reduce methane emissions in ruminant grazing systems.


Assuntos
Metano/análise , Animais , Cervos , Dieta , Ecossistema , Europa (Continente) , Humanos , Ovinos
3.
Microbes Environ ; 35(1)2020.
Artigo em Inglês | MEDLINE | ID: mdl-31932538

RESUMO

Accretionary prisms are thick masses of sedimentary material scraped from the oceanic crust and piled up at convergent plate boundaries found across large regions of the world. Large amounts of anoxic groundwater and natural gas, mainly methane (CH4), are contained in deep aquifers associated with these accretionary prisms. To identify the subsurface environments and potential for CH4 production by the microbial communities in deep aquifers, we performed chemical and microbiological assays on groundwater and natural gas derived from deep aquifers associated with an accretionary prism and its overlying sedimentary layers. Physicochemical analyses of groundwater and natural gas suggested wide variations in the features of the six deep aquifers tested. On the other hand, a stable carbon isotope analysis of dissolved inorganic carbon in the groundwater and CH4 in the natural gas showed that the deep aquifers contained CH4 of biogenic or mixed biogenic and thermogenic origins. Live/dead staining of microbial cells contained in the groundwater revealed that the cell density of live microbial cells was in the order of 104 to 106| |cells| |mL-1, and cell viability ranged between 7.5 and 38.9%. A DNA analysis and anoxic culture of microorganisms in the groundwater suggested a high potential for CH4 production by a syntrophic consortium of hydrogen (H2)-producing fermentative bacteria and H2-utilizing methanogenic archaea. These results suggest that the biodegradation of organic matter in ancient sediments contributes to CH4 production in the deep aquifers associated with this accretionary prism as well as its overlying sedimentary layers.


Assuntos
Sedimentos Geológicos/microbiologia , Água Subterrânea/microbiologia , Metano/biossíntese , Consórcios Microbianos , Anaerobiose , Archaea/classificação , Archaea/genética , Archaea/isolamento & purificação , Archaea/metabolismo , Bactérias/classificação , Bactérias/genética , Bactérias/isolamento & purificação , Bactérias/metabolismo , Carbono/análise , Sedimentos Geológicos/química , Água Subterrânea/química , Hidrogênio/metabolismo , Japão , Metano/análise , Gás Natural/análise , RNA Ribossômico 16S/genética
4.
Nat Commun ; 11(1): 407, 2020 01 21.
Artigo em Inglês | MEDLINE | ID: mdl-31964892

RESUMO

Conversion of tropical peat swamp forest to drainage-based agriculture alters greenhouse gas (GHG) production, but the magnitude of these changes remains highly uncertain. Current emissions factors for oil palm grown on drained peat do not account for temporal variation over the plantation cycle and only consider CO2 emissions. Here, we present direct measurements of GHGs emitted during the conversion from peat swamp forest to oil palm plantation, accounting for CH4 and N2O as well as CO2. Our results demonstrate that emissions factors for converted peat swamp forest is in the range 70-117 t CO2 eq ha-1 yr-1 (95% confidence interval, CI), with CO2 and N2O responsible for ca. 60 and ca. 40% of this value, respectively. These GHG emissions suggest that conversion of Southeast Asian peat swamp forest is contributing between 16.6 and 27.9% (95% CI) of combined total national GHG emissions from Malaysia and Indonesia or 0.44 and 0.74% (95% CI) of annual global emissions.


Assuntos
Agricultura , Monitoramento Ambiental/estatística & dados numéricos , Gases de Efeito Estufa/metabolismo , Phoeniceae/metabolismo , Árvores/metabolismo , Dióxido de Carbono/análise , Dióxido de Carbono/metabolismo , Florestas , Gases de Efeito Estufa/análise , Indonésia , Malásia , Metano/análise , Metano/metabolismo , Óxido Nitroso/análise , Óxido Nitroso/metabolismo , Áreas Alagadas
5.
Chemosphere ; 239: 124795, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31520977

RESUMO

Greenhouse gas (GHG) emissions from constructed wetlands (CWs) have raised environmental concern and thus offset their environmental and ecological benefits. This study evaluated the influence of plant species, i.e., Canna indica (C. indica), Cyperus alternifolius (C. alternifolius), Phragmites australis (P. australis) and unplanted control, on GHG emissions, pollutant removal and associated microbial abundance in subsurface flow constructed wetland (SSFCW) mesocosms. C. indica outperformed the other tested plant species in pollutant removal, and the presence of plants irrespective of species enhanced the removal efficiencies of nitrogen, phosphorus and organics in SSFCW mesocosms compared to unplanted control. The greatest carbon dioxide (CO2) flux (582.01 ±â€¯89.25 mg/m2/h), methane (CH4) flux (21.88 ±â€¯2.51 µg/m2/h) and nitrous oxide (N2O) flux (37.27 ±â€¯15.82 µg/m2/h) were observed in mesocosms planted with C. indica, P. australis and C.alternifolius, respectively. Unexpectedly, the mcrA and pmoA genes were not detected in any mesocosms. For denitrifiers, the N2O fluxes showed a significantly (p < 0.05) positive correlation with nirS and nirK genes abundance. The abundance of nosZ gene (ranged from 0.18 × 104 to 0.75 × 104 copies/mg gravel) and nosZ/(nirS + nirK) (ranged from 1.29 × 10-4 to 2.12 × 10-4 copies/mg gravel) in this study was lower than that in most reported studies. Regarding the global warming potential (GWP), the lowest value was observed in mesocosms planted with C. indica. In conclusion, C. indica is selected as the optimal plant species in this study due to its lower GWP and excellent pollutant removal performance.


Assuntos
Gases de Efeito Estufa/análise , Magnoliopsida/fisiologia , Eliminação de Resíduos Líquidos/métodos , Áreas Alagadas , Dióxido de Carbono/análise , Desnitrificação , Metano/análise , Nitrogênio/metabolismo , Óxido Nitroso/análise , Fósforo/metabolismo , Especificidade da Espécie , Águas Residuárias/análise
6.
J Dairy Sci ; 103(1): 1031-1046, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31759588

RESUMO

The carbon footprint of milk from year-round grazed-pasture dairy systems and its variability has had limited research. The objective of this study was to determine temporal, regional, and farm system variability in the carbon footprint of milk from New Zealand (NZ) average dairy production. Farm production and input data were collected from a national database for 2010/11 to 2017/18 across regions of NZ and weighted on relative production supplied to the major dairy cooperative Fonterra to produce an NZ-average. Total greenhouse gas emissions were calculated using a life cycle assessment methodology for the cradle-to-farm gate, covering all on- and off-farm contributing sources. The NZ-average carbon footprint of milk varied from 0.81 kg of CO2 equivalent (CO2eq)/kg of fat- and protein-corrected milk (FPCM) in 2010/11 (with widespread drought) to 0.75 to 0.78 kg of CO2eq/kg of FPCM in 2013/14 to 2017/18, with a trend for a small decrease over time. Regional variation occurred with highest carbon footprint values for the Northland region due to greatest climatic and soil limitations on pasture production. Dairy cattle diet was approximately 85% from grazed pasture with up to 15% from brought-in feeds (mainly forages and by-products). The CO2 emissions from direct fuel and electricity use constituted <2% of total CO2eq emissions, whereas enteric methane was near 70% of the total. An estimate of potential contribution from direct land use change (plantation forest to pasture) was 0.13 kg of CO2eq/kg of FPCM. This was not included because nationally there has been a net increase in forest land and a decrease in pasture land over the last 20 yr. Data used were highly representative, as evident by the same estimated carbon footprint from 368 farms (in 2017/18) from the national database compared with that from a direct survey of 7,146 farms. New Zealand-specific nitrous oxide emission factors were used, based on many validated field trials and as used in the NZ greenhouse gas inventory, resulting in an 18% lower carbon footprint than if default Intergovernmental Panel on Climate Change factors had been used. Evaluation of the upper and lower quartiles of farms based on per-cow milk production (6,044 vs. 3,542 kg of FPCM/cow) showed a 15% lower carbon footprint for the upper quartile of farms, illustrating the potential for further decrease in carbon footprint with improved farm management practices.


Assuntos
Pegada de Carbono , Bovinos/fisiologia , Indústria de Laticínios/métodos , Leite , Animais , Mudança Climática , Dieta/veterinária , Monitoramento Ambiental , Fazendas , Feminino , Gases de Efeito Estufa , Metano/análise , Nova Zelândia
7.
J Sci Food Agric ; 100(5): 1922-1930, 2020 Mar 30.
Artigo em Inglês | MEDLINE | ID: mdl-31846083

RESUMO

BACKGROUND: Ten varieties of alfalfa (Medicago sativa L.) were evaluated for saponin content. Two of the most promising varieties were chosen so that their effect on rumen fermentation and methane production could be studied. Initially, four Hohenheim gas tests (HGT) were performed to test the effect of increased levels of total saponin extracted from the two alfalfa cultivars (Kometa and Verko) - either as fresh material or ensiled - on the total bacteria, total protozoa, methane emission, and selected methanogenic population. Afterwards, seven particular saponins were extracted from fresh alfalfa of the Kometa variety and tested in 24 h batch fermentation culture experiments. RESULTS: The ensiled forms of both the Verko and Kometa alfalfa varieties seem to be good sources of saponin, capable of reducing methane production (P < 0.05) without negatively affecting the basic fermentation parameters. Of the two evaluated varieties, Kometa was the most effective, and the saponins extracted from its roots 3-Glc,28-Glc Ma, medicagenic saponin, and 3-Glu Ma showed the most evident effect (P = 0.0001). The most promising aerial alfalfa saponin in mitigating methane production was soysaponin I K salt (P = 0.0001). Three mixtures of saponins were tested and all were found to mitigate methane production; however, one mixture (MIX 1) did so only to a very small extent. CONCLUSION: Saponins have been observed to have differing effects depending on their source; however, the mode of action of saponins depends on their direct or probable indirect effect on the microorganisms involved in methane production. © 2019 Society of Chemical Industry.


Assuntos
Bovinos/metabolismo , Medicago sativa/metabolismo , Metano/metabolismo , Rúmen/metabolismo , Saponinas/metabolismo , Ração Animal/análise , Animais , Digestão , Fermentação , Medicago sativa/química , Metano/análise , Saponinas/análise
8.
ISME J ; 14(1): 274-287, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31624343

RESUMO

Lakes are a significant source of atmospheric methane, although methane-oxidizing bacteria consume most methane diffusing upward from anoxic sediments. Diverse methane-oxidizing bacteria form an effective methane filter in the water column of stratified lakes, yet, niche partitioning of different methane-oxidizing bacteria along the oxygen-methane counter gradient remains poorly understood. In our study, we reveal vertical distribution patterns of active methane-oxidizing bacteria along the oxygen-methane counter gradient of four lakes, based on amplicon sequencing analysis of 16S rRNA and pmoA genes, and 16S rRNA and pmoA transcripts, and potential methane oxidation rates. Differential distribution patterns indicated that ecologically different methane-oxidizing bacteria occupied the methane-deficient and oxygen-deficient part above and below the oxygen-methane interface. The interface sometimes harbored additional taxa. Within the dominant Methylococcales, an uncultivated taxon (CABC2E06) occurred mainly under methane-deficient conditions, whereas Crenothrix-related taxa preferred oxygen-deficient conditions. Candidatus Methylomirabilis limnetica (NC10 phylum) abundantly populated the oxygen-deficient part in two of four lakes. We reason that the methane filter in lakes is structured and that methane-oxidizing bacteria may rely on niche-specific adaptations for methane oxidation along the oxygen-methane counter gradient. Niche partitioning of methane-oxidizing bacteria might support greater overall resource consumption, contributing to the high effectivity of the lacustrine methane filter.


Assuntos
Lagos/microbiologia , Metano/metabolismo , Methylococcaceae/isolamento & purificação , Ecossistema , Gammaproteobacteria/isolamento & purificação , Lagos/química , Metano/análise , Methylococcaceae/genética , Methylococcaceae/metabolismo , Oxirredução , Oxigênio/análise , Filogenia , RNA Ribossômico 16S/genética
9.
J Dairy Sci ; 103(2): 2024-2039, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31864736

RESUMO

Since heritability of CH4 emissions in ruminants was demonstrated, various attempts to generate large individual animal CH4 data sets have been initiated. Predicting individual CH4 emissions based on equations using milk mid-infrared (MIR) spectra is currently considered promising as a low-cost proxy. However, the CH4 emission predicted by MIR in individuals still has to be confirmed by measurements. In addition, it remains unclear how low CH4 emitting cows differ in intake, digestion, and efficiency from high CH4 emitters. In the current study, putatively low and putatively high CH4 emitting Brown Swiss cows were selected from the entire Swiss herdbook population (176,611 cows), using an MIR-based prediction equation. Eventually, 15 low and 15 high CH4 emitters from 29 different farms were chosen for a respiration chamber (RC) experiment in which all cows were fed the same forage-based diet. Several traits related to intake, digestion, and efficiency were quantified over 8 d, and CH4 emission was measured in 4 open circuit RC. Daily CH4 emissions were also estimated using data from 2 laser CH4 detectors (LMD). The MIR-predicted CH4 production (g/d) was quite constant in low and high emission categories, in individuals across sites (home farm, experimental station), and within equations (first available and refined versions). The variation of the MIR-predicted values was substantially lower using the refined equation. However, the predicted low and high emitting cows (n = 28) did not differ on average in daily CH4 emissions measured either with RC or estimated using LMD, and no correlation was found between CH4 predictions (MIR) and CH4 emissions measured in RC. When individuals were recategorized based on CH4 yield measured in RC, differences between categories of 10 low and 10 high CH4 emitters were about 20%. Low CH4 emitting cows had a higher feed intake, milk yield, and residual feed intake, but they differed only weakly in eating pattern and digesta mean retention times. Low CH4 emitters were characterized by lower acetate and higher propionate proportions of total ruminal volatile fatty acids. We concluded that the current MIR-based CH4 predictions are not accurate enough to be implemented in breeding programs for cows fed forage-based diets. In addition, low CH4 emitting cows have to be characterized in more detail using mechanistic studies to clarify in more detail the properties that explain the functional differences found in comparison with other cows.


Assuntos
Bovinos/fisiologia , Comportamento Alimentar , Metano/análise , Leite/química , Espectrofotometria Infravermelho/veterinária , Animais , Dieta/veterinária , Digestão , Feminino , Lactação , Lasers , Metano/metabolismo , Rúmen/metabolismo
10.
Sci Total Environ ; 698: 134212, 2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-31783470

RESUMO

Rice, one of the major sources of CH4 and N2O emissions, is also the largest consumer of water resources. Mild alternate wetting and drying (AWD) irrigation is widely adopted to save irrigation water resources and maintain rice production, but its effects on CH4 and N2O emissions are unclear. In addition, previous studies have revealed different effects of mid-season drainage on global warming potential (GWP), owing to the different criteria used. In this study, a pot experiment was conducted to investigate the effects of mild AWD irrigation and mid-season drainage (a specific soil moisture) on CH4 and N2O emissions during rice cultivation. Four water management systems were applied: AWD + D0 (mild AWD irrigation without mid-season drainage), AWD + D1 (mild AWD irrigation with mid-season drainage), CF + D0 (continuous flooding without mid-season drainage) and CF + D1 (continuous flooding with mid-season drainage); nitrogen was applied at two levels (N90 and N180) along with each treatment. The results showed that mild AWD irrigation reduced CH4 cumulative emissions by an average of 87.1% but increased N2O cumulative emissions by an average of 280% compared to the values observed with CF irrigation. Mid-season drainage did not affect N2O emissions but interrupted CH4 fluxes and significantly reduced CH4 cumulative emissions. CH4 and N2O cumulative emissions were reduced by an average of 25.0% and 54.2%, respectively, with N90 application compared to values observed with N180 application. Unexpectedly, mild AWD irrigation did not reduce GWP and yield-scaled GWP unlike CF irrigation because a high N2O emission peak occurred during mild AWD irrigation. Furthermore, we observed an obvious trade-off between CH4 and N2O. We suggest that maintaining flooding during nitrogen application but applying mild AWD irrigation for the remaining period may be helpful in reducing CH4 and N2O emissions and GWP.


Assuntos
Agricultura/métodos , Poluentes Atmosféricos/análise , Metano/análise , Dióxido de Nitrogênio/análise , Oryza
11.
Environ Sci Pollut Res Int ; 26(36): 36124-36140, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31748998

RESUMO

A rapid growth in the development of power generation and transportation sectors would result in an increase in the carbon dioxide (CO2) concentration in the atmosphere. As it will continue to play a vital role in meeting current and future needs, significant efforts have been made to address this problem. Over the past few years, extensive studies on the development of heterogeneous catalysts for CO2 methanation have been investigated and reported in the literatures. In this paper, a comprehensive overview of methanation research studies over lanthanide oxide catalysts has been reviewed. The utilisation of lanthanide oxides as CO2 methanation catalysts performed an outstanding result of CO2 conversion and improvised the conversion of acidity from CO2 gas to CH4 gas. The innovations of catalysts towards the reaction were discussed in details including the influence of preparation methods, the structure-activity relationships as well as the mechanism with the purpose of outlining the pathways for future development of the methanation process.


Assuntos
Dióxido de Carbono/análise , Lantânio/química , Metano/análise , Gás Natural/análise , Óxidos/química , Catálise
12.
Environ Sci Pollut Res Int ; 26(36): 37082-37091, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31745784

RESUMO

Municipal solid waste landfills are not only a crucial source of global greenhouse gas emissions; they also produce large amounts of ammonia (NH3), hydrogen sulfide, and other odorous gases that negatively affect the regional environment. Several types of methane-oxidizing bacteria (MOB) were proved to be effective in mitigating methane emission from landfills. Nevertheless, more MOB species and their technical parameters for best mitigating methane still need to be explored. In landfills, methane is simultaneously generated with ammonia, which may impede the CH4 bio-oxidizing process of MOB. However, very limited studies examined the enhancement of methane reduction by introducing ammonia-oxidizing bacteria (AOB) in landfills. In this study, two enriched MOB cultures were gained from a typical municipal solid waste landfill, and then were cultured with three strains of ammonia-oxidizing bacteria (AOB). The MOB enrichment culture used in this work includes Methylocaldum, Methylocystaceae, and Methyloversatilis, with a methane oxidation capacity of 43.6-65.0%, and the AOB includes Candida ethanolica, Bacillus cereus, and Alcaligenes faecalis. The effects on the emission reduction of both NH3 and CH4 were measured using self-made landfill-simulating equipment, as MOB, AOB, and a MOB-AOB mixture were added to the soil cover of the simulation equipment. The concentrations of CH4 and NH3 in the MOB-AOB mixture group decreased sharply, and the CH4 and NH3 concentration was 76.4% and 83.7% of the control group level. We also found that addition of AOB can help MOB oxidize CH4 and improve the emission reduction effect.


Assuntos
Poluentes Atmosféricos/análise , Amônia/metabolismo , Metano/metabolismo , Eliminação de Resíduos , Instalações de Eliminação de Resíduos , Amônia/análise , Metano/análise , Methylococcaceae , Oxirredução , Solo , Microbiologia do Solo , Resíduos Sólidos
13.
Environ Sci Pollut Res Int ; 26(36): 36845-36856, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31745796

RESUMO

This study investigated the impact of adding zeolite (F), superphosphate (G), and ferrous sulfate (L) in various combinations on reducing greenhouse gas (GHG) emission and improving nitrogen conservation during factory-scale chicken manure composting, aimed to identify the combination that optimizes the performance of the process. Chicken manure was mixed with F, G, FL, or FGL and subjected to windrow composting for 46 days. Results showed that global warming potential (GWP) was reduced by 21.9% (F), 22.8% (FL), 36.1% (G), and 39.3% (FGL). Further, the nitrogen content in the final composting product increased by 27.25%, 9.45%, and 21.86% in G, FL, and FGL amendments, respectively. The fertilizer efficiency of the compost product was assessed by measuring the biomass of plants grown in it, and it was consistent with the nitrogen content. N2O emission was negligible during composting, and 98% of the released GHGs comprised CO2 and CH4. Reduction in GHG emission was mainly achieved by reducing CH4 emission. The addition of FL, G, and FGL caused a clear shift in the abundance of dominant methanogens; particularly, the abundance of Methanobrevibacter decreased and that of Methanobacterium and Methanocella increased, which was correlated with CH4 emissions. Meanwhile, the changes in moisture content, NH4+-N content, and pH level also played an important role in the reduction of GHG emission. Based on the effects of nitrogen conservation, fertilizer efficiency improvement, and GHG emission reduction, we conclude that G and FGL are more beneficial than F or FL and suggest these additives for efficient chicken manure composting.


Assuntos
Compostagem , Difosfatos/química , Fertilizantes/análise , Gases de Efeito Estufa/análise , Esterco , Zeolitas/química , Animais , Galinhas , Aquecimento Global , Metano/análise , Nitrogênio/análise , Óxido Nitroso/análise , 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.
Mar Pollut Bull ; 149: 110568, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31550579

RESUMO

This study used a self-developed a NDIR monitoring system to continuously monitor GHG emissions from a tidal constructed mangrove wetland at three typical habitats (mudflat, mangrove, and water surface) in four seasons. The NDIR monitoring system is able to explore the diurnal and seasonal variation of GHG emissions from the tidal constructed mangrove wetland and to estimate more precisely for the GHG emission based carbon budget of the wetland. The continuous monitoring technique is feasible and valuable for assessing the temporal variation of GHG uptake/emission to/from the wetland. Daytime CO2 emissions were always lower than those at nighttime due to photosynthesis process, while an opposite trend was observed for CH4 and N2O emissions. Seasonal variation of GHGs showed that the highest GHG emissions was observed in summer, and followed by fall, spring, and winter. For three typical habitats, mangrove emitted more amounts of GHGs than mudflat and water surface.


Assuntos
Sequestro de Carbono , Gases de Efeito Estufa/análise , Áreas Alagadas , Dióxido de Carbono/análise , Ecossistema , Metano/análise , Óxido Nitroso/análise , Estações do Ano , Taiwan
16.
Environ Sci Pollut Res Int ; 26(31): 31956-31980, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31493080

RESUMO

The Southern Junggar Basin (SJB) in China is an emerging coalbed methane (CBM) development area with abundant low-rank CBM resources. CBM development is accomplished by pumping significant volumes of water from the aquifer, and this water is commonly termed as produced water, which has great utilization values for the water-deficient areas like SJB. Geochemistry signatures are prerequisites in the management of the produced water. Meanwhile, geochemistry surveys of this produced water could also help study the basin hydrogeology and then serve the CBM development. In this study, geochemical compositions of the produced waters, including major ions, stable isotopic compositions, trace elements, and rare earth elements, were analyzed. Results show that produced waters from CBM wells in the SJB are of Na-HCO3 type and have wide total dissolved solid (TDS) ranges from 963 to 11,916 mg/L (avg. 7417 mg/L). Cl-, Na+, and HCO3- are the principal determinates of the TDS contents of the produced waters, and their concentrations all increase with greater depth of the produced waters. Overall, the net results of groundwater-aquifer mineral-bacteria interactions with groundwater flowing along the flow path are to deplete Ca2+, Mg2+, and SO42- and increase Na+, Cl-, HCO3-, and TDS. Stable isotopic values of the CBM produced waters (δDH2O and δ18OH2O) cluster along or below the local meteoric water line (LMWL), and the shift of stable isotopic values to the right side of LMWL was affected by a joint effect of evaporation and mixing with near-surface water. Trace elements that exceed the regulated concentrations for drinking water of China include As, Fe, Mn, Ba, and Ni, among which Ba and Fe need to be most concerned because over 50% of the CBM produced waters exceed the regulated values. Through principal component analysis, the trace element associations in the CBM produced waters and their potential origins were analyzed. The ∑REY concentrations of the CBM produced waters increase exponentially with the increase of pH and present a certain correlation with TDS. The relationship between ∑REY concentrations and TDS reflects different water-rock reaction degrees and hydrogeological backgrounds.


Assuntos
Água Subterrânea/análise , Metano/análise , Oligoelementos/análise , Poluentes Químicos da Água/análise , China , Água Subterrânea/química , Metano/química , Oligoelementos/química , Poços de Água
17.
Sci Total Environ ; 690: 1342-1354, 2019 Nov 10.
Artigo em Inglês | MEDLINE | ID: mdl-31470496

RESUMO

Oil and gas development can result in natural gas migration into shallow groundwater. Methane (CH4), the primary component of natural gas, can subsequently react with solutes and minerals in the aquifer to create byproducts that affect groundwater chemistry. Hydro-biogeochemical processes induced by fugitive gas from leaky oil and gas wells are currently not well understood. We monitored the hydro-biogeochemical responses of a controlled natural gas release into a well-studied Pleistocene beach sand aquifer (Canadian Forces Base Borden, Ontario, Canada). Groundwater samples were collected before, during, and up to 700 days after gas injection and analyzed for pH, major and minor ions, alkalinity, dissolved gases, stable carbon isotope ratios of CO2 and CH4, and microbial community composition. Gas injection resulted in a dispersed plume of free and dissolved phase natural gas, affecting groundwater chemistry in two distinct temporal phases. Initially (i.e. during and immediately after gas injection), pH declined and major ions and trace elements fluctuated; at times increasing above baseline concentrations. Changes in the short-term were due to invasion of deep groundwater with elevated total dissolved solids entrained with the upward migration of free phase gas and, reactions that were instigated through the introduction of constituents other than CH4 present in the injected gas (e.g. CO2). At later times, more pronounced aerobic and anaerobic CH4 oxidation led to subtle increases in major ions (e.g. Ca2+, H4SiO4) and trace elements (e.g. As, Cr). Microbial community profiling indicated a persistent perturbation to community composition with a conspicuous ingrowth of taxa implicated in aerobic CH4 oxidation as well anaerobic S, N and Fe species metabolism.


Assuntos
Monitoramento Ambiental , Água Subterrânea/química , Metano/análise , Campos de Petróleo e Gás , Poluentes Químicos da Água/análise , Gás Natural , Ontário
18.
Sci Total Environ ; 697: 133945, 2019 Dec 20.
Artigo em Inglês | MEDLINE | ID: mdl-31473551

RESUMO

The strength of methane (CH4) source of mangroves is not well understood, especially when including all CH4 pathways in consideration. This study measured CH4 fluxes by five pathways (sediments, pneumatophores, water surface, leaves, and stems) from four typical mangrove forests, including Kandelia candel without pneumatophores and three species with pneumatophores: Sonneratia apetala, Laguncularia racemosa and Bruguiera gymnorhiza-Bruguiera sexangula. The CH4 fluxes from sediments were 4.82±1.46mgCH4m-2h-1 for K. candel and 1.36±0.17mgCH4m-2h-1 for the other three with pneumatophores. Among the three communities with pneumatophores, S. apetala community had significantly greater emission rate than the other two (P<0.05). Pneumatophores in S. apetala were found to significantly decrease CH4 emission from sediments (P<0.01), while those in B. gymnorhiza-B. sexangula were significantly increase it (P<0.05). CH4 fluxes from waters were 3.48±1.11mgCH4m-2h-1, with the highest emission rate in the K. candel community for the duck farming. Leaves of mangroves except for those of K. candel were a weak CH4 daytime sink, but stems were a weak source. The total 72ha of mangroves in the Changning river basin emitted about 8.10Gg CH4 per year, with a weighted emission rate of about 1.29mgCH4m-2h-1. Our results suggested that mangroves are only a small methane source to atmosphere with great contribution from sediments and waters, only slight contribution from leaves and stems. Pneumatophores of different mangrove species played different roles in CH4 fluxes from sediments.


Assuntos
Poluentes Atmosféricos/análise , Espécies Introduzidas , Metano/análise , Áreas Alagadas , China , Monitoramento Ambiental , Rhizophoraceae
19.
Sci Total Environ ; 697: 133840, 2019 Dec 20.
Artigo em Inglês | MEDLINE | ID: mdl-31487598

RESUMO

The effects of different moisture contents on greenhouse gas (GHG) emissions from pig manure (PM) digested by black soldier fly larvae (BSFL) as well as the accompanying changes of nitrogen and carbon contents in gaseous emissions and residues were studied. A mixture of PM and corncob at the ratio of 2.2:1 was prepared with a moisture content of 45%. Then, distilled water was added to adjust the moisture contents of the mixture to 55%, 65%, 75% and 85%, respectively. The prepared mixtures were digested by BSFL for eight days. The results indicated that BSFL could reduce CH4, N2O and NH3 emissions respectively by 72.63-99.99%, 99.68%-99.91% and 82.30-89.92%, compared with conventional composting, while CO2 emissions increased potentially due to BSFL metabolism. With increasing moisture content, the cumulative CH4 emissions increased, while cumulative NH3 emissions peaked at 55% moisture content and then decreased. Interestingly, the tendency of total cumulative CO2 emissions was consistent with that of the total weight of BSFL. The total GHG emissions were about only 1% those from of traditional composting at the optimum moisture content (75%), which was the most favorable for the growth of BSFL. The nitrogen and carbon contents of BSFL content in all treatments accounted for 1.03%-12.67% and 0.25%-4.68% of the initial contents in the raw materials, respectively. Moreover, the residues retained 71.12%-90.58% carbon and 67.91%-80.39% nitrogen of the initial raw materials. Overall, our results suggest that BSFL treatment is an environment-friendly alternative for decreasing CH4, N2O and NH3 emissions as well as reducing global warming potential (GWP).


Assuntos
Compostagem , Gases de Efeito Estufa/análise , Esterco , Metano/análise , Simuliidae/fisiologia , Animais , Fertilizantes , Nitrogênio/análise
20.
Ying Yong Sheng Tai Xue Bao ; 30(9): 3126-3136, 2019 Sep.
Artigo em Chinês | MEDLINE | ID: mdl-31529888

RESUMO

To understand the effects of different irrigation amounts on soil CO2, N2O, and CH4 emission characteristics and tomato yield, and further put forward effective reduction measures, we carried out an experiment with three irrigation levels: full irrigation (1.0W, W1.0; W meant irrigation amount needed to provide the adequate water), 20% deficit irrigation (0.8W, W0.8) and 40% deficit irrigation (0.6W, W0.6). We used static closed chamber and gas chromatography method to measure greenhouse gas emission in two consecutive greenhouse tomato rotation cycles from April to December, 2017. The results showed that cumulative soil CO2, N2O and CH4 emissions increased with increasing irrigation amounts in the two growing seasons (W1.0>W0.8>W0.6), and significant difference of N2O between W0.6 and W1.0 was observed, while other treatment effects on soil gas emissions were not obvious. Compared to W1.0, cumulative soil CO2 emissions were decreased by 12.2% and 8.3%, cumulative soil N2O emissions were decreased by 19.1% and 8.0%, and cumulative soil CH4 emissions were reduced by 11.0% and 6.2% for W0.6 and W0.8, respectively. Tomato yield and global warming potential of soil N2O and CH4 emissions (GWP) increased as irrigation amount increasing. Compared with W1.0, W0.6 significantly decreased tomato yield by 17.0% and GWP by 22.9%, while the difference between the effects of W0.8 and W1.0 on these two parameters was not significant. Global warming potential per tomato yield presented an increase then a decrease as irrigation amount increasing (W0.8>W1.0>W0.6), but without stanificance. Irrigation water use efficiency (IWUE) showed a decrease with increasing irrigation amount. Compared with W1.0, IWUE under W0.6 and W0.8 was increased by 38.3% and 9.4%, respectively. Soil CO2 flux was nega-tively and exponentially correlated with soil moisture. The dependence of soil CH4 flux on soil moisture showed a significantly positive correlation. An exponential negative correlation was observed between the soil N2O ux and soil temperature when soil temperature was below or above 18 ℃. Irrigation increased tomato yield and soil greenhouse gas emissions, but decreased IWUE. Therefore, W0.8 was the best mode of irrigation management when synthetically considering tomato yield, IWUE, and greenhouse effect.


Assuntos
Agricultura , Gases de Efeito Estufa/análise , Solo , Dióxido de Carbono/análise , Lycopersicon esculentum/crescimento & desenvolvimento , Metano/análise , Óxido Nitroso/análise
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