scholarly journals Evaluating alternative ebullition models for predicting peatland methane emission and its pathways via data-model fusion

2021 ◽  
Author(s):  
Shuang Ma ◽  
Lifen Jiang ◽  
Rachel M. Wilson ◽  
Jeff P. Chanton ◽  
Scott Bridgham ◽  
...  
Keyword(s):  
Model Parameters ◽  
Ch4 Emission ◽  
Deep Soil ◽  
Concentration Data ◽  
Ch4 Flux ◽  
Ch4 Emissions ◽  
Ch4 Production ◽  
Underlying Mechanisms ◽  
Improved Model ◽  
Threshold Approach

Abstract. Understanding the dynamics of peatland methane (CH4) emissions and quantifying sources of uncertainty in estimating peatland CH4 emissions are critical for mitigating climate change. The relative contributions of CH4 emission pathways through ebullition, plant-mediated transport, and diffusion together with their different transport rates and vulnerability to oxidation determine the quantity of CH4 to be oxidized before leaving the soil. Notwithstanding their importance, the relative contributions of the emission pathways have not been well characterized by experiments or modeling approaches. In particular, the ebullition process is more uncertain and can lead to large uncertainties in modeled CH4 emissions. To improve model simulations of CH4 emission and its pathways, we evaluated two model structures: 1) the Ebullition Bubble Growth volume threshold approach (EBG) and 2) the modified Ebullition Concentration Threshold approach (ECT) using CH4 flux and concentration data collected in a peatland in northern Minnesota, USA. When model parameters were constrained using observed CH4 fluxes, the CH4 emissions simulated by the EBG approach (RMSE = 0.53) had a better agreement with observations than the ECT approach (RMSE = 0.61). Further, the EBG approach simulated a smaller contribution from ebullition but more frequent ebullition events than the ECT approach. The EBG approach yielded greatly improved simulations of pore water CH4 concentrations, especially in the deep soil layers, compared to the ECT approach. When constraining the EBG model with both CH4 flux and concentration data in model-data fusion, uncertainty of the modeled CH4 concentration profiles was reduced by 78 to 86 % in comparison to constraints based on CH4 flux data alone. The improved model capability was attributed to the well-constrained parameters regulating the CH4 production and emission pathways. Our results suggest that the EBG modeling approach better characterizes CH4 emission and underlying mechanisms. Moreover, to achieve the best model results both CH4 flux and concentration data are required to constrain model parameterization.

scholarly journals Multi-year effect of wetting on CH<sub>4</sub> flux at taiga–tundra boundary in northeastern Siberia deduced from stable isotope ratios of CH<sub>4</sub>

2019 ◽  
Vol 16 (3) ◽  
pp. 755-768 ◽  
Author(s):  
Ryo Shingubara ◽  
Atsuko Sugimoto ◽  
Jun Murase ◽  
Go Iwahana ◽  
Shunsuke Tei ◽  
...  
Keyword(s):  
Water Saturation ◽  
Methane Flux ◽  
Interannual Variations ◽  
Ch4 Emission ◽  
Ch4 Flux ◽  
Ch4 Production ◽  
Year Effect ◽  
Northeastern Siberia ◽  
Order Of Magnitude ◽  
Acetoclastic Methanogenesis

Abstract. The response of CH4 emission from natural wetlands due to meteorological conditions is important because of its strong greenhouse effect. To understand the relationship between CH4 flux and wetting, we observed interannual variations in chamber CH4 flux, as well as the concentration, δ13C, and δD of dissolved CH4 during the summer from 2009 to 2013 at the taiga–tundra boundary in the vicinity of Chokurdakh (70∘37′ N, 147∘55′ E), located on the lowlands of the Indigirka River in northeastern Siberia. We also conducted soil incubation experiments to interpret δ13C and δD of dissolved CH4 and to investigate variations in CH4 production and oxidation processes. Methane flux showed large interannual variations in wet areas of sphagnum mosses and sedges (36–140 mg CH4 m−2 day−1 emitted). Increased CH4 emission was recorded in the summer of 2011 when a wetting event with extreme precipitation occurred. Although water level decreased from 2011 to 2013, CH4 emission remained relatively high in 2012, and increased further in 2013. Thaw depth became deeper from 2011 to 2013, which may partly explain the increase in CH4 emission. Moreover, dissolved CH4 concentration rose sharply by 1 order of magnitude from 2011 to 2012, and increased further from 2012 to 2013. Large variations in δ13C and δD of dissolved CH4 were observed in 2011, and smaller variations were seen in 2012 and 2013, suggesting both enhancement of CH4 production and less significance of CH4 oxidation relative to the larger pool of dissolved CH4. These multi-year effects of wetting on CH4 dynamics may have been caused by continued soil reduction across multiple years following the wetting. Delayed activation of acetoclastic methanogenesis following soil reduction could also have contributed to the enhancement of CH4 production. These processes suggest that duration of water saturation in the active layer can be important for predicting CH4 emission following a wetting event in the permafrost ecosystem.

Feeding lucerne silage to beef cattle at three allowances and four feeding frequencies affects circadian patterns of methane emissions, but not emissions per unit of intake

2014 ◽  
Vol 54 (9) ◽  
pp. 1350 ◽  
Author(s):  
Arjan Jonker ◽  
German Molano ◽  
Christopher Antwi ◽  
Garry Waghorn
Keyword(s):  
Emission Rate ◽  
Circadian Variation ◽  
Emission Rates ◽  
Ch4 Emission ◽  
Feeding Frequency ◽  
Ch4 Emissions ◽  
Time To Peak ◽  
Ch4 Production ◽  
Ad Libitum ◽  
Circadian Patterns

The objective of this study was to determine the circadian variation in methane (CH4) emissions from cattle fed lucerne silage at different feeding levels and feeding frequencies, to assist with interpretation of short ‘snapshot’ CH4 measurements used for predicting daily emissions. Eight Hereford × Friesian heifers (initially 20 months of age) were used in five consecutive periods (P1–5) of 14 days with CH4 emissions measured using respiration chambers for two consecutive days at the end of each period. Feed was restricted to intakes of ~6, 8, 8, 8 and 11 ± 1.3 (ad libitum) kg lucerne silage dry matter (DM), fed in 2, 2, 3, 4 or ad libitum (refilled twice daily) meals per day in P1–5, respectively. Daily CH4 production (g/day) was lower in P1 than in P2–4 (P < 0.05), which were lower than in P5 (P < 0.05), but CH4 yield (24.3 ± 1.23 g/kg DM) was unaffected by treatment. Among the five periods, CH4 emission rate (g/h) before feeding ranged from 1.8 to 6.5 g/h, time to peak CH4 production after start of feeding ranged from 19 to 40 min and peak CH4 production rate ranged from 11.1 to 17.5 g/h. The range in hourly CH4 emission rates during the day decreased with increasing feed intake level, but was unaffected by feeding frequency. In summary, the circadian pattern of CH4 emissions was affected by feed allowance and feeding frequency, and variation in CH4 emission rate was reduced with increasing intake, without affecting average daily yield (g CH4/kg DM intake).

scholarly journals How methane emission from rice paddy is affected by management practices and region?

2018 ◽  
Author(s):  
Jinyang Wang ◽  
Hiroko Akiyama ◽  
Kazuyuki Yagi ◽  
Xiaoyuan Yan
Keyword(s):  
Management Practices ◽  
Organic Amendment ◽  
Water Status ◽  
Regional Scale ◽  
Rice Fields ◽  
Ch4 Emission ◽  
Ch4 Flux ◽  
Ch4 Emissions ◽  
Flooded Rice ◽  
Previous Season

Abstract. Rice cultivation has long been known as one of the dominant anthropogenic contributors to methane (CH4) emissions, yet there is still uncertainty when estimating its emissions at the global/regional scale. An increasing number of rice field measurements have been conducted globally, which allow us to assess the major variables controlling CH4 emissions and develop the region- and country-specific emission factors (EFs). Results shown that the CH4 flux from rice fields were closely related to organic amendment, water regime during and before the rice-growing season, soil properties and climate. The average CH4 flux from fields with single and multiple drainages were 71 % and 55 % of that from continuously flooded rice fields. The CH4 flux from fields that were flooded in the previous season were 2.4 and 2.7 times that from fields previously drained for a short and long season. Contrary to the previously reported optimum soil pH of around neutrality, paddy soils with pH of 5.0–5.5 gave the maximum CH4 emission. Rice straw applied at 6 t ha−1 shortly before rice transplanting can increase CH4 emission by 3.2 times, while it increases CH4 emission by only 1.6 times when applied in the previous season. The default EF was estimated to 1.19 kg CH4 ha−1 d−1 with a 95 % confidence interval of 0.80 to 1.76 kg CH4 ha−1 d−1 for continuously flooded rice fields without organic amendment and with a preseason water status of short drainage. The default EFs at sub-regional and country levels were also estimated. We conclude that these default EFs and scaling factors can be used to develop national or regional emission inventories.

scholarly journals Hysteretic temperature sensitivity of wetland CH<sub>4</sub> fluxes explained by substrate availability and microbial activity

2020 ◽  
Author(s):  
Kuang-Yu Chang ◽  
William J. Riley ◽  
Patrick M. Crill ◽  
Robert F. Grant ◽  
Scott R. Saleska
Keyword(s):  
Temperature Sensitivity ◽  
Global Climate ◽  
Mechanistic Modeling ◽  
Biogeochemical Model ◽  
Ch4 Emission ◽  
Substrate Availability ◽  
Ch4 Emissions ◽  
Ch4 Production ◽  
Biogeochemical Models ◽  
Abiotic Interactions

Abstract. Methane (CH4) emissions from wetlands are likely increasing and important in global climate change assessments. However, contemporary terrestrial biogeochemical model predictions of CH4 emissions are very uncertain, at least in part due to prescribed temperature sensitivity of CH4 production and emission. While statistically consistent apparent CH4 emission temperature dependencies have been inferred from meta-analyses across microbial to ecosystem scales, year-round ecosystem-scale observations have contradicted that finding. Using flux observations and mechanistic modeling in two heavily studied high-latitude research sites (Stordalen, Sweden, and Utqiaġvik, Alaska, USA), we show here that substrate-mediated hysteretic microbial and abiotic interactions lead to intra-seasonally varying temperature sensitivity of CH4 production and emission. We find that seasonally varying substrate availability drives lower and higher modeled methanogen biomass and activity, and thereby CH4 production, during the earlier and later periods of the thawed season, respectively. Our findings demonstrate the uncertainty of inferring CH4 emission or production from temperature alone, and highlight the need to represent microbial and abiotic interactions in wetland biogeochemical models.

scholarly journals Methane paradox in tropical lakes? Sedimentary fluxes rather than water column production in oxic waters sustain methanotrophy and emissions to the atmosphere

2020 ◽  
Author(s):  
Cédric Morana ◽  
Steven Bouillon ◽  
Vimac Nolla-Ardèvol ◽  
Fleur A. E. Roland ◽  
William Okello ◽  
...  
Keyword(s):  
Surface Waters ◽  
Tropical Lakes ◽  
Large Lakes ◽  
Ch4 Flux ◽  
Ch4 Emissions ◽  
Isotope Tracer ◽  
Ch4 Production ◽  
Elevated Water ◽  
Lake Size ◽  
Sunlight Intensity

Abstract. Despite growing evidence that methane (CH4) formation could also occur in well-oxygenated surface freshwaters, its significance at the ecosystem scale is uncertain. Empirical models based on data gathered at high latitude predict that the contribution of oxic CH4 increases with lake size and should represent the majority of CH4 emissions in large lakes. However, such predictive models could not directly apply to tropical lakes which differ from their temperate counterparts in some fundamental characteristics, such as year-round elevated water temperature. We conducted stable isotope tracer experiments which revealed that oxic CH4 production is closely related to phytoplankton metabolism, and is a common feature in five contrasting African lakes. Nevertheless, methanotrophic activity in surface waters and CH4 emissions to the atmosphere were predominantly fuelled by CH4 generated in sediments and physically transported to the surface. Indeed, measured CH4 bubble dissolution flux and diffusive benthic CH4 flux were several orders of magnitude higher than CH4 production in surface waters. Microbial CH4 consumption dramatically decreased with increasing sunlight intensity, suggesting that the freshwater CH4 paradox might be also partly explained by photo-inhibition of CH4 oxidizers in the illuminated zone. Sunlight appeared as an overlooked but important factor determining the CH4 dynamics in surface waters, directly affecting its production by photoautotrophs and consumption by methanotrophs.

scholarly journals Methane production and nitrogen balance of dairy heifers grazing palisade grass cv. Marandu alone or with forage peanut

2019 ◽  
Vol 97 (11) ◽  
pp. 4625-4634 ◽  
Author(s):  
Andressa S Berça ◽  
Abmael Da S Cardoso ◽  
Vanessa Z Longhini ◽  
Luís O Tedeschi ◽  
Robert Michael Boddey ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Management Strategies ◽  
N Fertilization ◽  
Neutral Detergent Fiber ◽  
N Balance ◽  
Ch4 Emission ◽  
Purine Derivatives ◽  
Ch4 Emissions ◽  
Dairy Heifers ◽  
Ch4 Production

Abstract Livestock production systems are an essential agribusiness activity in Brazil, but a critical challenge of Brazilian farmers is to maintain the equilibrium of the ecosystem, using herbage resources efficiently with a minimum impact on the environment. Nitrogen (N) fertilization and the inclusion of forage legumes into tropical grass pastures are management strategies which increase the productivity and nutritive value of pastures and may also affect methane (CH4) production by ruminants. The objective of this study was to examine the effects of either fertilizing palisade grass pastures with N or including the forage peanut (Arachis pintoi) into grass pastures on enteric CH4 emission, microbial protein production in the rumen via purine derivatives in the urine, and N balance. Twenty-one nonlactating crossbred dairy heifers were used in a completely randomized design with 3 treatments. The treatments consisted of pastures of palisade grass without N fertilization (control), fertilized with urea (fertilized), and palisade grass mixed with forage peanut (mixed). Seven animals (replications) were used to evaluate dry matter intake, digestibility, CH4 emission, urea, purine derivatives, and volume of urine, and N ingestion and excretion. Four paddocks (replications) were used to measure herbage mass; morphological, botanical, and chemical composition of herbage; and herbage allowance. The CH4 emissions were determined using the sulfur hexafluoride (SF6) tracer gas technique. The efficiency of N utilization (ENU) was calculated using the N balance data. Crude protein (CP) concentration of herbage increased with fertilization or legumes inclusion (P < 0.0001) while neutral detergent fiber (NDF) concentration decreased (P = 0.0355). The leaf allowance was higher in the fertilized treatment (P = 0.0294). Only uric acid excretion increased with N fertilization (P = 0.0204). The ENU was not affected by fertilized or mixed compared to control and averaged 55% (P = 0.8945). The enteric CH4 production was similar between treatments and averaged 129 g/d (P = 0.3989). We concluded that the changes in chemical composition of herbage provided by N fertilization or the inclusion of the legume showed no reduction in enteric CH4 emissions, but the ENU was more significant than previous studies with palisade grass, suggesting that different management strategies might alter the ENU under grazing conditions.

scholarly journals Hysteretic temperature sensitivity of wetland CH<sub>4</sub> fluxes explained by substrate availability and microbial activity

2020 ◽  
Vol 17 (22) ◽  
pp. 5849-5860
Author(s):  
Kuang-Yu Chang ◽  
William J. Riley ◽  
Patrick M. Crill ◽  
Robert F. Grant ◽  
Scott R. Saleska
Keyword(s):  
Temperature Sensitivity ◽  
Seasonal Variability ◽  
Global Climate ◽  
Biogeochemical Model ◽  
Ch4 Emission ◽  
Substrate Availability ◽  
Ch4 Emissions ◽  
Ch4 Production ◽  
Biogeochemical Models ◽  
Abiotic Interactions

Abstract. Methane (CH4) emissions from wetlands are likely increasing and important in global climate change assessments. However, contemporary terrestrial biogeochemical model predictions of CH4 emissions are very uncertain, at least in part due to prescribed temperature sensitivity of CH4 production and emission. While statistically consistent apparent CH4 emission temperature dependencies have been inferred from meta-analyses across microbial to ecosystem scales, year-round ecosystem-scale observations have contradicted that finding. Here, we show that apparent CH4 emission temperature dependencies inferred from year-round chamber measurements exhibit substantial intra-seasonal variability, suggesting that using static temperature relations to predict CH4 emissions is mechanistically flawed. Our model results indicate that such intra-seasonal variability is driven by substrate-mediated microbial and abiotic interactions: seasonal cycles in substrate availability favors CH4 production later in the season, leading to hysteretic temperature sensitivity of CH4 production and emission. Our findings demonstrate the uncertainty of inferring CH4 emission or production rates from temperature alone and highlight the need to represent microbial and abiotic interactions in wetland biogeochemical models.

scholarly journals Pendugaan Emisi Metana pada Sistem Pengelolaan Tanaman Padi di Kabupaten Minahasa (The Estimation of Methane Emission in The Rice Management System in Minahasa Rregency)

2012 ◽  
Vol 2 (1) ◽  
Author(s):  
Susan Marlein Mambu
Keyword(s):  
Methane Emission ◽  
Rice Fields ◽  
Soil Types ◽  
Wetland Rice ◽  
Calculation Formula ◽  
Ch4 Emission ◽  
Irrigated Rice ◽  
Ch4 Emissions ◽  
Ch4 Production ◽  
Over Time

AbstrakPemanasan bumi secara global karena emisi gas rumah kaca ke atmosfir yang disebabkan oleh kegiatan manusia, cenderung mengalami peningkatan dari waktu ke waktu. Pertanian padi sawah, khususnya sawah teririgasi juga merupakan penyumbang terbesar gas metana ke atmosfer. Oleh karena itu, perlu adanya upaya pengurangan emisi CH4 dari kegiatan budidaya tanaman padi sawah. Penelitian dilakukan untuk mengetahui emisi CH4 dari budidaya padi sawah di kabupaten Minahasa, dengan melakukan estimasi emisi CH4 menggunakan model perhitungan formula untuk estimasi emisi CH4 pada padi sawah. Hasil penelitian ini memberikan informasi keberadaan CH4 dan jumlah produksi emisi CH4 dari lahan padi sawah di Kabupaten Minahasa, yang cenderung mengalami peningkatan dari tahun ke tahun (data tahun 2002 – 2010). Peningkatan emisi CH4 dari lahan padi sawah di Kabupaten Minahasa disebabkan oleh beberapa faktor yaitu luas panen, jenis tanah, jenis varietas, jenis pengairan dan kegiatan budidaya lainnya seperti pemupukan dan pemberian bahan organik (jerami).Kata kunci: emisi metana, padi sawahAbstractGlobal warming from greenhouse gas emissions to the atmosphere that is caused by human activities tends to be increased over time. Fields of wetland rice, particularly irrigated rice, are also the largest contributor to methane gas to the atmosphere. Therefore, CH4 emissions should be reduced from paddy rice cultivation. This research aimed to measure the production of CH4 emission in the wetland rice fields of Minahasa, using a model calculation formula to estimate CH4 emissions in the rice fields. The results informed the existence and the amount of CH4 production resulted from wetland rice fields in Minahasa, which tended to be increased from year to year (data of year 2002 to 2010). The increment of CH4 emission from wetland rice fields in Minahasa was caused by several factors, i.e. the harvested area, soil types, types of variety, types of irrigation and other cultivation activities such as fertilization and providing organic material (straw).Keywords: methane emission, wetland rice

scholarly journals Methane paradox in tropical lakes? Sedimentary fluxes rather than pelagic production in oxic conditions sustain methanotrophy and emissions to the atmosphere

2020 ◽  
Vol 17 (20) ◽  
pp. 5209-5221
Author(s):  
Cédric Morana ◽  
Steven Bouillon ◽  
Vimac Nolla-Ardèvol ◽  
Fleur A. E. Roland ◽  
William Okello ◽  
...  
Keyword(s):  
Surface Waters ◽  
Tropical Lakes ◽  
Large Lakes ◽  
Ch4 Flux ◽  
Ch4 Emissions ◽  
Isotope Tracer ◽  
Ch4 Production ◽  
Elevated Water ◽  
Lake Size ◽  
Sunlight Intensity

Abstract. Despite growing evidence that methane (CH4) formation could also occur in well-oxygenated surface fresh waters, its significance at the ecosystem scale is uncertain. Empirical models based on data gathered at high latitude predict that the contribution of oxic CH4 increases with lake size and should represent the majority of CH4 emissions in large lakes. However, such predictive models could not directly apply to tropical lakes, which differ from their temperate counterparts in some fundamental characteristics, such as year-round elevated water temperature. We conducted stable-isotope tracer experiments, which revealed that oxic CH4 production is closely related to phytoplankton metabolism and is a common feature in five contrasting African lakes. Nevertheless, methanotrophic activity in surface waters and CH4 emissions to the atmosphere were predominantly fuelled by CH4 generated in sediments and physically transported to the surface. Indeed, CH4 bubble dissolution flux and diffusive benthic CH4 flux were several orders of magnitude higher than CH4 production in surface waters. Microbial CH4 consumption dramatically decreased with increasing sunlight intensity, suggesting that the freshwater “CH4 paradox” might be also partly explained by photo-inhibition of CH4 oxidizers in the illuminated zone. Sunlight appeared as an overlooked but important factor determining the CH4 dynamics in surface waters, directly affecting its production by photoautotrophs and consumption by methanotrophs.

scholarly journals Constraining global methane emissions and uptake by ecosystems

2011 ◽  
Vol 8 (1) ◽  
pp. 221-272 ◽  
Author(s):  
R. Spahni ◽  
R. Wania ◽  
L. Neef ◽  
M. van Weele ◽  
I. Pison ◽  
...  
Keyword(s):  
Atmospheric Carbon Dioxide ◽  
Model Parameters ◽  
Rice Agriculture ◽  
Surface Exchange ◽  
Ch4 Emissions ◽  
Ch4 Production ◽  
Mineral Soils ◽  
The Tropics ◽  
Northern Peatlands ◽  
Atmospheric Inversions

Abstract. Natural methane (CH4) emissions from wet ecosystems are an important part of today's global CH4 budget. Climate affects the exchange of CH4 between ecosystems and the atmosphere by influencing CH4 production, oxidation, and transport in the soil. The net CH4 exchange depends on ecosystem hydrology, soil and vegetation characteristics. Here, the LPJ-WHyMe global dynamical vegetation model is used to simulate global net CH4 emissions for different ecosystems: northern peatlands (45°–90° N), naturally inundated wetlands (60° S–45° N), rice agriculture and wet mineral soils. Mineral soils are a potential CH4 sink, but can also be a source with the direction of the net exchange depending on soil moisture content. The geographical and seasonal distributions are evaluated against multi-dimensional atmospheric inversions for 2003–2005, using two independent four-dimensional variational assimilation systems. The atmospheric inversions are constrained by the atmospheric CH4 observations of the SCIAMACHY satellite instrument and global surface networks. Compared to LPJ-WHyMe the inversions result in a significant reduction in the emissions from northern peatlands and suggest that LPJ-WHyMe maximum annual emissions peak about one month late. The inversions do not put strong constraints on the division of sources between inundated wetlands and wet mineral soils in the tropics. Based on the inversion results we adapt model parameters in LPJ-WHyMe and simulate the surface exchange of CH4 over the period 1990–2008. Over the whole period we infer an increase of global ecosystem CH4 emissions of +1.11 Tg CH4 yr−1, not considering potential additional changes in wetland extent. The increase in simulated CH4 emissions is attributed to enhanced soil respiration resulting from the observed rise in land temperature and in atmospheric carbon dioxide that were used as input. The long-term decline of the atmospheric CH4 growth rate from 1990 to 2006 cannot be fully explained with the simulated ecosystem emissions. However, these emissions show an increasing trend of +3.62 Tg CH4 yr−1 over 2005–2008 which can partly explain the renewed increase in atmospheric CH4 concentration during recent years.

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