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Peatlands are vital in the global carbon cycle, acting as significant sinks for carbon and releasing methane (CH4) and carbon dioxide (CO2) into the atmosphere. However, the complex interactions between environmental factors and the microbial communities responsible for these greenhouse gas emissions remain insufficiently understood. To address this knowledge gap, a pilot-scale mesocosm study was conducted to assess the impact of different terminal electron acceptors (TEAs), including sulfate (SO42-), humic acid (HA), and goethite, on CH4 and CO2 emissions and microbial community structures in peatlands. Our results revealed that the addition of TEAs significantly altered the CH4 and CO2 emissions. Specifically, the addition of SO42- nearly doubled CO2 production while substantially inhibiting CH4 emissions. The combined addition of SO42- and HA, as well as HA alone, followed a similar pattern, albeit with less pronounced effects on CH4. Goethite addition resulted in the highest inhibition of CH4 among all treatments but did not significantly increase CO2 production. Community composition and network analysis indicated that TEAs primarily determined the structure of microbial communities, with each treatment exhibiting distinct taxa networks. Proteobacteria, Acidobacteria, Chloroflexi, and Bacteroidetes were the most abundant phyla across all mesocosms. The presence of methanotrophs, including Methylomirabilales and Methylococcales, was linked to the inhibition of CH4 emissions in these mesocosms. This study provides novel insights into the spatial variability of microbial diversity and density in peatlands under various TEAs, emphasizing the role of methanogenesis and CO2 fluxes in carbon cycling. Our findings enhance the understanding of carbon cycling in microbe-rich environments exposed to TEAs and highlight the potential for future studies to investigate the long-term effects of TEAs on microbial communities, enzymes, and carbon storage. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Agro-Environment Science is the property of Journal of Agro-Environment Science Editorial Board and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Peatlands are vital in the global carbon cycle, acting as significant sinks for carbon and releasing methane (CH4) and carbon dioxide (CO2) into the atmosphere. However, the complex interactions between environmental factors and the microbial communities responsible for these greenhouse gas emissions remain insufficiently understood. To address this knowledge gap, a pilot-scale mesocosm study was conducted to assess the impact of different terminal electron acceptors (TEAs), including sulfate (SO42−), humic acid (HA), and goethite, on CH4 and CO2 emissions and microbial community structures in peatlands. Our results revealed that the addition of TEAs significantly altered the CH4 and CO2 emissions. Specifically, the addition of SO42− nearly doubled CO2 production while substantially inhibiting CH4 emissions. The combined addition of SO42− and HA, as well as HA alone, followed a similar pattern, albeit with less pronounced effects on CH4. Goethite addition resulted in the highest inhibition of CH4 among all treatments but did not significantly increase CO2 production. Community composition and network analysis indicated that TEAs primarily determined the structure of microbial communities, with each treatment exhibiting distinct taxa networks. Proteobacteria, Acidobacteria, Chloroflexi, and Bacteroidetes were the most abundant phyla across all mesocosms. The presence of methanotrophs, including Methylomirabilales and Methylococcales, was linked to the inhibition of CH4 emissions in these mesocosms. This study provides novel insights into the spatial variability of microbial diversity and density in peatlands under various TEAs, emphasizing the role of methanogenesis and CO2 fluxes in carbon cycling. Our findings enhance the understanding of carbon cycling in microbe-rich environments exposed to TEAs and highlight the potential for future studies to investigate the long-term effects of TEAs on microbial communities, enzymes, and carbon storage.

Ruminant animals, such as dairy cattle, produce CH4, which contributes to global warming emissions and reduces dietary energy for the cows. While the carbon foot print of milk production varies based on production systems, milk yield and farm management practices, enteric fermentation, and manure management are major contributors togreenhouse gas emissions from dairy cattle. Recent emerging evidence has revealed the existence of genetic variation for CH4 emission traits among dairy cattle, suggests their potential inclusion in breeding goals and genetic selection programs. Advancements in high-throughput sequencing technologies and analytical techniques have enabled the identification of potential metabolic biomarkers, candidate genes, and SNPs linked to methane emissions. Indeed, this review critically examines our current understanding of carbon foot print in milk production, major emission sources, rumen microbial community and enteric fermentation, and the genetic architecture of methane emission traits in dairy cattle. It also emphasizes important implications for breeding strategies aimed at halting methane emissions through selective breeding, microbiome driven breeding, breeding for feed efficiency, and breeding by gene editing.

Summary: Tree stem methane emissions are important components of lowland forest methane budgets. The potential for species‐specific behaviour among co‐occurring lowland trees with contrasting bark characteristics has not been investigated.We compare bark‐mediated methane transport in two common lowland species of contrasting bark characteristics (Melaleuca quinquenervia featuring spongy/layered bark with longitudinally continuous airspaces and Casuarina glauca featuring hard/dense common bark) through several manipulative experiments.First, the progressive cutting through M. quinquenervia bark layers caused exponential increases in methane fluxes (c. 3 orders of magnitude); however, sapwood‐only fluxes were lower, suggesting that upward/axial methane transport occurs between bark layers. Second, concentrated methane pulse‐injections into exposed M. quinquenervia bark, revealed rapid axial methane transport rates (1.42 mm s−1), which were further supported through laboratory‐simulated experiments (1.41 mm s−1). Laboratory‐simulated radial CH4 diffusion rates (through bark) were c. 20‐times slower. Finally, girdling M. quinquenervia stems caused a near‐instantaneous decrease in methane flux immediately above the cut. By contrast, girdling C. glauca displayed persistent, though diminished, methane fluxes.Overall, the experiments revealed evidence for rapid 'between‐bark' methane transport independent from the transpiration stream in M. quinquenervia, which facilitates diffusive axial transport from the rhizosphere and/or sapwood sources. This contrasts with the slower, radial 'through‐bark' diffusive‐dominated gas transportation in C. glauca. See also the Commentary on this article by Ward & Megonigal, 242: 5–7. [ABSTRACT FROM AUTHOR]

Biochar has been recognized as one of the most important negative emission technologies due to its indirect removal of atmospheric carbon dioxide. However, how biochar incorporation converts rice paddy into carbon negative and enhances soil carbon sequestration (SOCS) remain largely unexplored, especially under alternate wetting and drying irrigation (IAWD). A 3-yr field experiment was conducted utilizing a split-plot design with continuous flooding irrigation (ICF) and IAWD as main plots and two biochar incorporations at the rate of 0 t ha−1 (B0) and 20 t ha−1 (B20) as sub-plots. Results indicated that IAWD reduced CH4 emissions by 73 %, GWP by 69 %, and greenhouse gas emission intensity (GHGI) by 69 % on average, but increased N2O emissions by 109 % over the three years. Biochar inhibited N2O emissions by 31 % over the three years, increased grain yield by 5 % and 11 %, and reduced CH4 emissions by 22 % and 38 % in the 2nd and 3rd year, although a 6 % lower grain yield was observed in the 1st year. Biochar can increase SOCS and SOCS rate more remarkably under IAWD than ICF. Biochar coupled with IAWD obtained the highest SOCS (56.9 t C ha−1) and lowest net GWP (-23.0 t CO2-eq ha−1) and efficiently inhibited the negative effect of IAWD on the increase in N2O emissions. Moreover, compared with ICFB0, ICFB20 and IAWDB20 decreased net GWP by nearly 4 and 8 times, which was mainly attributed to a substantial increase in SOCS (48.3 and 56.9 t C ha−1) through biochar incorporation. The further decline in net GWP comparing IAWDB20 with ICFB20 was caused by decreased GWP under IAWD. Therefore, biochar combined IAWD offers significant benefits in mitigating net greenhouse gases emissions and promoting soil C sequestration in paddy ecosystems.

Copyright of Journal of Ecology & Rural Environment is the property of Journal of Ecology & Rural Environment Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

To determine the difference in greenhouse gas emissions between two rice (Oryza sativa L.) varieties; Takanari (Tak) and Koshihikari (Kos), under organic rice cultivation with or without weeds management, a pot experiment was conducted at Tsuruoka, Yamagata, Japan. The Tak and Kos varieties were transplanted individually and interplanted as Tak+Kos, with the main treatments of weeding (w) and no-weeding (nw). Methane (CH4), nitrous oxide (N2O), and plant night respiration (CO2 emission) fluxes were measured once weekly or biweekly during the rice growth period. As the results, N2O fluxes were not detected but CH4 fluxes varied with the rice growth stage for all treatments. Compared with the Kos(w), Tak(w) and Tak+Kos(w) significantly decreased total seasonal CH4 emissions by 12.4% and 19.1%, respectively. This was attributed to higher rhizospheric CH4 oxidation and the offset of potential methanogenic activities because of the larger root biomass and a higher harvest index for both Tak(w) and Tak+Kos(w) compared with Kos(w). Conversely, Kos(nw) significantly reduced cumulative CH4 emissions by 31.7% and 48.6% compared with Tak(nw) and Tak+Kos(nw), respectively. This was ascribed to high rhizospheric CH4 oxidation promoted by the presence of significantly higher weed biomass for Kos(nw) at 65.0% and 44.0% compared with Tak(nw) and Tak+Kos(nw), respectively. On average, the no-weeding practice significantly decreased cumulative CH4 emissions by 50.5% compared with the weeding practice, with a significantly high (P<0.001) interaction between weed management and variety differences observed. The CH4 emissions and plant biomass under variety interplanting (Tak+Kos) were not significantly different to Tak individual planting, but were significantly different to Kos individual planting, which implied variety Tak had strong competition to variety Kos. More studies on appropriate variety choice and pairs, and the effect of aquatic weeds presence in no-weeding organic paddy fields are necessary to estimate CH4 emission and attenuation. [ABSTRACT FROM AUTHOR]

Copyright of Journal of South China Agricultural University is the property of Gai Kan Bian Wei Hui and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Chinese Journal of Applied Ecology / Yingyong Shengtai Xuebao is the property of Chinese Journal of Applied Ecology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of South China Agricultural University is the property of Gai Kan Bian Wei Hui and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Sea level rise driven by global warming is threatening low-lying and reclaimed agricultural areas near coasts. The most marginalized of these with low crop yield can be converted into new valuable wetland ecosystems with high CO2 mitigation capacity by removing drainage systems or performing managed realignment. This study assessed CO2 and CH4 dynamics before and after forming two adjacent wetlands by flooding reclaimed agricultural land. The Gyldensteen Coastal Lagoon (214 ha) is an open system flooded with seawater, and the neighboring Lake Engsø (144 ha) is a closed system flooded with freshwater. Before flooding in 2014, the total area was a net source of about 10,350 Mg CO2 yr−1 due to aerobic microbial soil respiration. The temporal and spatial pattern of CO2 and CH4 release changed after flooding in a pattern that depended on soil biogeochemistry, temperature, and other environmental factors. Thus, there were strong exponential temperature dependencies of CO2 and CH4 emissions. Slow anaerobic microbial action in the Coastal Lagoon soil and the presence of sulfate prevented CO2 and CH4 emission, leading to a slight net uptake of CO2 in 2019 (−70 Mg CO2 yr−1). Conversely, methanogenesis near the soil–water interface after freshwater flooding of Lake Engsø drove rapid emission of CH4 (diffusive and ebullitive) that doubled its greenhouse gas emissions. In conclusion, CH4 emissions in Lake Engsø therefore counteracted the CO2 mitigation effect by flooding and the total area remains a net source of greenhouse gases with an emission of 8330 CO2-equivalents yr−1. [ABSTRACT FROM AUTHOR]

Compared to diesel, liquefied natural gas (LNG), often used as an alternative fuel for marine engines, comes with significant advantages in reducing emissions of particulate matter (PM), SOx, CO2, and other pollutants. Promoting the use of LNG is of great significance for achieving carbon peaking and neutrality worldwide, as well as improving the energy structure. However, compared to diesel engines, medium- and high-speed marine LNG engines may produce higher methane (CH4) emissions and also have nitrogen oxide (NOx) emission issues. For the removal of CH4 and NOx from the exhaust of marine LNG engines, the traditional technical route of combining a methane oxidation catalyst (MOC) and an HN3 selective catalytic reduction system (NH3-SCR) will face problems, such as low conversion efficiency and high operation cost. In view of this, the technology of non-thermal plasma (NTP) combined with CH4-SCR is proposed. However, the synergistic mechanism between NTP and catalysts is still unclear, which limits the optimization of an NTP-CH4-SCR system. This article summarizes the synergistic mechanism of NTP and catalysts in the integrated treatment process of CH4 and NOx, including experimental analysis and numerical simulation. And the relevant impact parameters (such as electrode diameter, electrode shape, electrode material, and barrier material, etc.) of NTP reactor energy optimization are discussed. The work of this paper is of great significance for guiding the high-efficiency removal of CH4 and NOx for an NTP-CH4-SCR system. [ABSTRACT FROM AUTHOR]

Purpose: We sought to identify the effects of elevationally (1560−2160 m) driven climate (mean annual air temperatures of + 4.0 to + 10 oC and mean annual precipitation of 900–1200 mm), forest type and soil property variations on soil greenhouse gas (GHG) fluxes in the Qinling Mountains, China. Methods: Soil GHGs were monitored at five temperate forest sites using static chambers for two full years. The related edaphoclimatic parameters were also monitored. Results: The cumulative soil CO2 and N2O emissions and the CH4 uptake from the five sites ranged between 3.82 to 7.48 t CO2-C ha−1 yr−1, 1.19 to 2.25 kg N2O-N ha−1 yr−1, and 0.89 to 5.67 kg CH4-C ha−1 year−1, respectively. Average soil CO2 emissions decreased with increasing site elevation, whereas CH4 and N2O fluxes showed no clear relationship with site elevation. All sites were net CH4 sinks. Occasionally, soils switched to net sources of CH4 during summer or autumn rainfall events at all sites. All sites were net N2O sources although short periods of soil N2O uptake were observed during freeze–thaw cycles and during summer rainfall. The source strength of N2O and CH4 differed during summer and winter and snowfall which had direct effects on soil water content. Conclusions: Site elevation could be used as a predictive variable for constructing regional soil CO2 emissions budgets, whereas soil CH4 and N2O fluxes are driven by a more complex interplay of climatic and soil biochemical variables, which are more difficult to integrate on a regional scale. [ABSTRACT FROM AUTHOR]

Dams built on rivers can bring economic benefits to local production and are considered to be environmentally friendly. However, in recent years, many researchers found that the establishment of dams has created excellent conditions for the production of methane (CH4) in rivers, making it change from a "weak source" of rivers to a "strong source" of dams. In particular, reservoir dams have a great impact on CH4 emission in rivers within their regions in terms of time and space. Spatially, the sedimentary layer and water level fluctuation zone of reservoirs are the main direct and indirect causes of CH4 production. Temporally, the synergetic effect between water level adjustment of the reservoir dam and environmental factors leads to large changes in the substances of the water body, impacts on the production and transport of CH4. Finally, the generated CH4 is emitted into the atmosphere through several important emission modes: molecular diffusion, bubbling, and degassing. The contribution of CH4 emitted from reservoir dams to the global greenhouse effect cannot be ignored. [ABSTRACT FROM AUTHOR]

Organic manure application is crucial for the maintenance and improvement of soil fertility. However, it inevitably results in increased paddy CH4 emissions, restricting the use of organic manure in the rice fields. In the present study, two kinds of manures, rapidly composted manure (RCM) and non-composted manure (NCM), were investigated through a 19-week greenhouse experiment, during which the dynamics of CH4 emission, soil parameters (DOC, acetate, NH4+, NO3−, and SO42−), and communities of methanogens and methanotrophs were simultaneously measured. The results showed that NCM significantly enhanced CH4 emission, while RCM decreased CH4 emission by 65.03%; there was no significant difference with the manure-free treatment. In order to well understand the methanogenic process, the seasonal CH4 flux was divided into two periods, namely Stage 1 (before drainage) and Stage 2 (after drainage), on the basis of CH4 emission intensity. The different CH4 production abilities among the three treatments could contribute to the varied CH4 emissions at Stage 1. The much higher soil DOC concentrations were observed in the manure-amended soils (NCM- and RCM-treatments), which could correspondingly lead to the relative higher CH4 emissions compared to the control during Stage 1. Furthermore, the increased methanogenic abundance and the shifted methanogenic archaeal community characterized by the functionally stimulated growth of Methanosarcina genus were observed in the NCM-treated soils, which could consequently result in a higher CH4 emission from the NCM treatment relative to the RCM treatment. As for Stage 2, apart from the significant decrease in soil DOC, the increased contents of soil NO3− and SO42−, especially with the RCM-treated soils, were also detected following the drainage, which might retard CH4 production. The lower CH4 emission at Stage 2 could also be attributed to the vigorous aerobic CH4 oxidations, especially in the RCM-treated soils. As a support, the amount of methanotrophs revealed an increasing trend during the late rice growth period, as did the predominance of the methylotrophy of Methylophilaceae species, which showed robust co-occurrence with methanotrophs, inferring interspecies cooperation in methane oxidation. [ABSTRACT FROM AUTHOR]

Flooded rice is a source of atmospheric methane (CH4) which is one of the greenhouse gases that caused global warming flooded rice also, consumed high amounts of water despite its rare in Egypt. This study focuses on mitigation strategies to face those problems by testing organic fertilization under different cultivation methods, for rice varieties and their effect on CH4 flux and grain yield of rice. Two field trials were conducted at Sakha agriculture research station during 2021 and 2022 growing seasons, whereas the experiments were designed in split-split plot design with four replications. The main plot consisted of three planting methods; transplanting, furrow and drill. The sub plot involved two rice varieties namely, Giza 179 and Sakha supper300. The sup-sup plots were subjugated by organic fertilizer, rice straw compost, farm yard manure and filter mud compost as well as control treatment. The result of the study provides that rice cultivars are major causes of variations in CH4 fluxes. Sakha super300 rice variety contributed in increasing CH4 gas emission than Giza179 variety. CH4 emission depends on the type of organic matter, applied rice straw compost and farmyard manure increased methane gas emission than filter mud compost. CH4 gas emission decreased under furrow and drill cultivation methods meanwhile, the defense system of rice plants increased compared with transplanting. Yield and its components increased under transplanting compared with other cultivation methods, yield increased by applied organic matter than control. Giza179variety was better than Sakha super300variety under dry cultivation and produced a higher grain yield. To sum up, furrow irrigated rice using Giza179 rice variety fertilized by filter mud compost can reduce methane gas emission and save water in addition to obtaining better grain yield. [ABSTRACT FROM AUTHOR]

Lakes are important natural sources of atmospheric methane (CH4), which should be considered in global CH4 budget estimations. However, the CH4 emissions from lakes can be highly variable, and the emissions from the river inlet region were less studied, which seriously hamper our understanding of CH4 budget estimates of lakes. Here, field measurements from over six years (2012 to 2017) at Lake Taihu, a large eutrophic shallow lake with a complicated river network, were conducted to address the issue. Results show that the river inlet region of the lake was a hot spot of CH4 emission. The CH4 emission at the river inlet region with an annual mean value of 0.183 mmol m−2 d−1 was seven times higher than that at pelagic region (0.028 mmol m−2 d−1). Peak CH4 emission occurred in warm seasons, and the lowest in cold seasons at the pelagic region, but peak emission occurred in cold seasons at the river inlet region. The seasonal CH4 emission at the pelagic region can be explained by water temperature; however, less temperature dependency of CH4 emission at the river inlet region was found. The variability of CH4 emission was linked to pollution loadings, and CH4-rich water in the inflowing river likely sustained the large CH4 emission of river inlet region. [ABSTRACT FROM AUTHOR]

[Display omitted] • Animal-based GHG emissions are predicted with various machine learning algorithms. • N 2 O, CH 4 , and CO 2 emissions are modeled for all provinces of Turkey. • Features include animal populations, climate parameters, and agricultural areas. • Both forward (2021) and backward (2004–2009) predictions were made. Livestock is an essential source of livelihood and food. In the context of climate change, animal-based greenhouse gas (GHG) emissions are of great importance. This study predicted direct N 2 O Emissions, indirect N 2 O Emissions, CH 4 Emissions from manure management, CH 4 Emissions from enteric fermentation, and CO 2 Emissions as GHG emissions from animal sources for all provinces of Turkey using various machine learning algorithms. Animal populations, climate parameters, and agricultural area information are used to model GHG emissions. The proposed study includes two different analyses according to the number of features used. The CatBoost algorithm was primarily successful when using eight features according to Scenario-1 and twelve features according to Scenario-2. In Scenario-1, R2 values for GHG emission predictions for 2021 are obtained as 0.996, 0.996, 0.992, 0.999, and 0.996, respectively, while in Scenario-2, they are obtained as 0.995, 0.996, 0.984, 0.996, and 0.996. In Scenario-1, R2 values for GHG emission predictions for 2004–2009 are obtained as 0.976, 0.962, 0.982, 0.994, and 0.994, respectively, while in Scenario-2, they are obtained as 0.975, 0.957, 0.917, 0.993, and 0.993. According to the results, the model's performance was not improved by increasing the number of features used. Using fewer features gave more successful results. [ABSTRACT FROM AUTHOR]

Current study attempts to comprehend the complex interplay between wetland hydrological regime and balance between Methane (CH4) emission and Carbon dioxide (CO2) sequestration in the rain fed floodplain wetlands. A mapping of wetland was done based on consistency of water presence using water presence frequency (WPF) of ten years (2013–2022). Ground truth validation ensured the accuracy of the wetland mapping. To obtain an estimation of spatial balance, satellite image-based estimation was adopted. In this task, first, annual gross CH4 emission and CO2 sequestration were estimated separately by the estimation of seasonal emission and cycle-wise sequestration. The masses of gross annual emission and sequestration were then compared to determine net balance of gas regulation. The study also considered the atomic mass balance of carbon and the global warming potential (GWP) to standardize the greenhouse effects of these gases. The yearly total emission and sequestration were estimated 0.3 × 103 ton and 82.2 × 103 ton. Overall the wetland contributed positively in this balance by absorbing 81.9 × 103 ton surplus amount of CO2. As a result of such a surplus amount of CO2 sequestration, if the global warming potentiality (GWP) of the emitted CH4 is considered, then also the yearly sequestration remains surplus by 72.8 × 103 ton. This amount saves 7.3 million USD of fixation cost per year. In terms of atomic mass of C, yearly 22.2 × 103 ton was additionally sequestrated in wetland. This balance was investigated to have negatively associated with water presence consistency of the wetland. The water presence frequency (WPF) which portrays the consistency of water presence in the wetland, exhibited coefficient of correlation (r) value −0.5 with yearly balance CH4 emission and CO2 sequestration, indicating a negative association. This association of WPF was respectively positive and negative with CH4 emission and CO2 sequestration. Since the peripheral parts of wetland are often left behind from the focus of wetland restoration program and face massive encroachment. The present findings signify the vital role of hydrologically poor peripheral wetland parts in the balance and suggest to put emphasis on the conservation these parts for immense ecological and environmental importance. [ABSTRACT FROM AUTHOR]

Aim: Soil available carbon (C) and nitrogen (N) are essential substrates for microbial C and N cycle processes, and under soil hydrothermal conditions, they play a great role in CH4 emission in a rice-based system. However, the associated mechanisms are still not clear. This study aimed to explore the response of CH4 emission to soil hydrothermal conditions after N fertilization. Methods: A rice–wheat rotation (RW) field experiment with (RW-CN) or without (RW-NN) conventional N fertilization was conducted in Sichuan province, China. The effect of soil CH4 fluxes and the key factors (soil temperature, moisture, and available C and N) driving CH4 emissions were determined with and without N fertilization under a RW system. Results: During the rice cultivation seasons, cumulative CH4 emissions from RW-CN were 7–9 folds greater (193 ± 11.4 and 302 ± 28.3 kg C ha−1) than that during the wheat cultivation periods (21.7 ± 13.4 and 47.1 ± 20.5 kg C ha−1). However, seasonal CH4 emissions from RW-NN were comparable with those from RW-CN treatment, indicating that N fertilization had no marked effect on CH4 emissions in the present study. During the whole experimental period, the soil temperature sensitivity coefficient (Q10) of CH4 emission from RW-NN treatment was similar to that from RW-CN treatment (6.47 vs 6.69). During the rice-growing seasons, CH4 fluxes linearly positively correlated with soil temperature and dissolved organic carbon (DOC) content, but negatively correlated with soil DOC to dissolved inorganic nitrogen ratio (DOC/DIN) and flood depth (FD) for both treatments. Structural equation model revealed that soil temperature, soil DOC, DOC/DIN, and FD together accounted for 62% and 57% of CH4 emission for RW-CN and RW-NN treatment, respectively. Conclusions: In summary, to mitigate flooded rice-based CH4 emission, appropriate soil hydrothermal conditions and available C and N substrates should be maintained, such as keeping appropriate flood depth when applying N fertilizer to fields and maintaining soil DOC/DIN > 8. [ABSTRACT FROM AUTHOR]

Ruminant animals, such as dairy cattle, produce CH 4 , which contributes to global warming emissions and reduces dietary energy for the cows. While the carbon foot print of milk production varies based on production systems, milk yield and farm management practices, enteric fermentation, and manure management are major contributors togreenhouse gas emissions from dairy cattle. Recent emerging evidence has revealed the existence of genetic variation for CH 4 emission traits among dairy cattle, suggests their potential inclusion in breeding goals and genetic selection programs. Advancements in high-throughput sequencing technologies and analytical techniques have enabled the identification of potential metabolic biomarkers, candidate genes, and SNPs linked to methane emissions. Indeed, this review critically examines our current understanding of carbon foot print in milk production, major emission sources, rumen microbial community and enteric fermentation, and the genetic architecture of methane emission traits in dairy cattle. It also emphasizes important implications for breeding strategies aimed at halting methane emissions through selective breeding, microbiome driven breeding, breeding for feed efficiency, and breeding by gene editing.

Peatlands are vital in the global carbon cycle, acting as significant sinks for carbon and releasing methane (CH 4 ) and carbon dioxide (CO 2 ) into the atmosphere. However, the complex interactions between environmental factors and the microbial communities responsible for these greenhouse gas emissions remain insufficiently understood. To address this knowledge gap, a pilot-scale mesocosm study was conducted to assess the impact of different terminal electron acceptors (TEAs), including sulfate (SO 4 2- ), humic acid (HA), and goethite, on CH 4 and CO 2 emissions and microbial community structures in peatlands. Our results revealed that the addition of TEAs significantly altered the CH 4 and CO 2 emissions. Specifically, the addition of SO 4 2- nearly doubled CO 2 production while substantially inhibiting CH 4 emissions. The combined addition of SO 4 2- and HA, as well as HA alone, followed a similar pattern, albeit with less pronounced effects on CH 4 . Goethite addition resulted in the highest inhibition of CH 4 among all treatments but did not significantly increase CO 2 production. Community composition and network analysis indicated that TEAs primarily determined the structure of microbial communities, with each treatment exhibiting distinct taxa networks. Proteobacteria , Acidobacteria , Chloroflexi, and Bacteroidetes were the most abundant phyla across all mesocosms. The presence of methanotrophs, including Methylomirabilales and Methylococcales , was linked to the inhibition of CH 4 emissions in these mesocosms. This study provides novel insights into the spatial variability of microbial diversity and density in peatlands under various TEAs, emphasizing the role of methanogenesis and CO 2 fluxes in carbon cycling. Our findings enhance the understanding of carbon cycling in microbe-rich environments exposed to TEAs and highlight the potential for future studies to investigate the long-term effects of TEAs on microbial communities, enzymes, and carbon storage., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Shabbir, Qian, Faheem, Zhou and Yu.)

Arsenic (As) contamination and methane (CH 4 ) emissions co-occur in rice paddies. However, how As impacts CH 4 production, oxidation, and emission dynamics is unknown. Here, we investigated the abundances and activities of CH 4 -cycling microbes from 132 paddy soils with different As concentrations across continental China using metagenomics and the reverse transcription polymerase chain reaction. Our results revealed that As was a crucial factor affecting the abundance and distribution patterns of the mcrA gene, which is responsible for CH 4 production and anaerobic CH 4 oxidation. Laboratory incubation experiments showed that adding 30 mg kg -1 arsenate increased 13 CO 2 production by 10-fold, ultimately decreasing CH 4 emissions by 68.5%. The inhibition of CH 4 emissions by As was induced through three aspects: (1) the toxicity of As decreased the abundance and activity of the methanogens; (2) the adaptability and response of methanotrophs to As is beneficial for CH 4 oxidation under As stress; and (3) the more robust arsenate reduction would anaerobically consume more CH 4 in paddies. Additionally, significant positive correlations were observed between arsC and pmoA gene abundance in both the observational study and incubation experiment. These findings enhance our understanding of the mechanisms underlying the interactions between As and CH 4 cycling in soils.

Abstract Northern lakes are important sources of CH4 in the atmosphere under the background of permafrost thaw and winter warming. We synthesize studies on thermokarst lakes, including various carbon sources for CH4 emission and the influence of thermokarst drainage on carbon emission, to show the evasion potential of ancient carbon that stored in the permafrost and CH4 emission dynamics along with thermokarst lake evolution. Besides, we discuss the lake CH4 dynamics in seasonally ice-covered lakes, especially for under-ice CH4 accumulation and emission during spring ice melt and the possible influential factors for CH4 emission in ice-melt period. We summarize the latest findings and point out that further research should be conducted to investigate the possibility of abundant ancient carbon emission from thermokarst lakes under climate warming and quantify the contribution of ice-melt CH4 emission from northern lakes on a large scale.

[Display omitted] • Impact of slurry removal frequencies on CH 4 emission rate was monitored with one year. • Increased slurry removal frequencies could reduce the in-house methane emission. • CH 4 emission was less dependent on temperature with increased removal frequencies. • Increased removing frequencies decreased the SMAs significantly. Anaerobic digestion of animal slurry to produce biogas is the dominated treatment approach and a storage period is normally applied prior to digestion. Pre-storage, however, contributes to CH 4 emissions and results in loss of biogas potential. Manure management was found to be an efficient approach to reduce not only the on-site CH 4 emission but may also have extended influence on CH 4 emission/losses for storage and subsequent biogas process, while the connection remains unclear. The objective of this study was therefore to evaluate the impact of slurry management (e.g. removal frequency) on CH 4 emission (both on-site and storage process prior to biogas) and biogas yield. An experimental pig house for growing-finishing pigs (30–110 kg) and the relevant CH 4 emission was monitored for one year. In addition, the specific CH 4 activity (SMA) test was conducted and used as an alternative indicator to reflect the impact. Results showed that the manure management affected both on-site and subsequent methane emission; with increased manure removal frequencies, the methane emission became less dependent on variation of temperatures and the specific methanogenesis activity was significantly lower. The highest SMA (100 mL CH 4 gVS-1), for instance, was observed from the slurries with limited emptied times, which was 10 times of that from the slurries being emptied three times a week. These findings could enlighten the development of environmentally friendly strategies for animal slurry management and biogas production. [ABSTRACT FROM AUTHOR]

This paper used CH4 MOD model and emission factor method to calculate and analyze the CH4 emission from agricultural activities in Yunnan province, and used scenario analysis to project the agricultural CH4 emission in Yunnan province.The results showed that the total agricultural CH4 emission in Yunnan province rose in fluctuation, followed by a sharp decrease, and then remained stable from 2010 to 2019,in which the emission from animal intestinal fermentation contributed the most.From 2010 to 2019,the agricultural emission intensity of CH4 per unit agricultural added value in Yunnan province showed a downward trend, while the agricultural emission intensity per unit agricultural land area was fluctuating.The CH4 emission from agricultural activities in Yunnan province was projected to be in upward trends under three scenarios from 2020 to 2029.Therefore, CH4 emission reduction measures should be taken in rice cultivation, livestock and poultry breeding in order to achieve the goal of “double carbon” and build a beautiful China. [ABSTRACT FROM AUTHOR]

The application of biochar in conjunction with fertilizer in agricultural production Is one of the most promising types of management to improve soil quality. However, the effects on the soil microbial community and methane (CH4) emissions from the interactive mechanisms of biochar combined with fertilizer are unclear. In this study, soil column trial was conducted to monitor the surface water nitrogen, dissolved organic carbon (DOC) and CH4 emission dynamics during the process of leaching. Additionally, bacterial and archaeal communities of the soil (0-10 cm) amended with biochar derived from different pyrolysis temperatures (300°C, 500°C, and 700°C) were also analyzed. High-throughput sequencing revealed that the soil archaeal and bacterial community diversities increased under the biochar amendments. The CH4 emission flux of all the treatments in the whole leaching period ranged from 0.0001 to 2.04 µg m-2 h-1, and the DOC ranged from 1.86 to 24.4 mg L-1. Our results showed that biochar amendments significantly increase the soil pH, total nitrogen (TN), and DOC contents, while inhibiting the loss of NON during leaching. In addition, biochar addition increased the paddy soil CH4 emissions, which ascribed to the increasing ratio of the abundances of methanogens to methanotrophs. Consequently, the higher CH4 emissions were probably caused by the stimulation of methanogenic archaea under the biochar amendments. Thus, the results obtained in this study can be applied to guide the application of biochar on greenhouse gas emissions in paddy soil. [ABSTRACT FROM AUTHOR]

Objective: Native plants can be used as additives to replace antibiotics to improve ruminant feed utilization and animal health. An experiment was conducted to evaluate the effects of Gentiana straminea (GS) on nutrient digestibility, methane emissions, and energy metabolism of Simmental calves. Methods: Thirty-two (5-week-old) male Simmental clves, with initial body weight (BW) of 155±12 kg were fed the same basal diet of concentrates (26%), alfalfa hay (37%), and oat hay (37%) and were randomly separated into four treatment groups according to the amount of GS that was added to their basal diet. The four different groups received different amounts of GS as a supplement to their basal diet during whole experiment: (0 GS) 0 mg/kg BW, the control; (100 GS) 100 mg/kg BW; (200 GS) 200 mg/kg BW; and (300 GS) 300 mg/kg BW. Results: For calves in the 200 GS and 300 GS treatment groups, there was a significant increase in dry matter (DM) intake (p<0.01), average daily gain (ADG) (p<0.05), organic matter intake (p<0.05), DM digestibility (p<0.05), neutral detergent fibre (NDF) digestibility (p<0.05), and acid detergent fibre (ADF) digestibility (p<0.05). Dietary GS supplementation result in quadratic increases of DM intake (p<0.01), ADG (p<0.05), NDF intake (p<0.05), and ADF intake (p<0.05). Supplementing the basal diet with GS significantly increased nitrogen (N) retention (p<0.001) and the ratio of retention N to N intake (p<0.001). Supplementing the basal diet with GS significantly decreased methane (CH4) emissions (p<0.01), CH4/BW0.75 (p<0.05) and CH4 energy (CH4-E) (p<0.05). Dietary GS supplementation result in quadratic increases of CH4 (p<0.01) and CH4/DM intake (p<0.01). Compared with 0 GS, GS-supplemented diets significantly improved their gross energy intake (p<0.05). The metabolizable energy and digestive energy intake were significantly greater for calves in the 100 GS and 200 GS calves than for 0 GS calves (p<0.05). Conclusion: From this study, we conclude that supplementing calf diets with GS could improve utilization of feed, energy, and N, and may reduce CH4 emissions without having any negative effects on animal health. [ABSTRACT FROM AUTHOR]

Biochar has been recognized as one of the most important negative emission technologies due to its indirect removal of atmospheric carbon dioxide. However, how biochar incorporation converts rice paddy into carbon negative and enhances soil carbon sequestration (SOCS) remain largely unexplored, especially under alternate wetting and drying irrigation (I AWD). A 3-yr field experiment was conducted utilizing a split-plot design with continuous flooding irrigation (I CF) and I AWD as main plots and two biochar incorporations at the rate of 0 t ha−1 (B 0) and 20 t ha−1 (B 20) as sub-plots. Results indicated that I AWD reduced CH 4 emissions by 73 %, GWP by 69 %, and greenhouse gas emission intensity (GHGI) by 69 % on average, but increased N 2 O emissions by 109 % over the three years. Biochar inhibited N 2 O emissions by 31 % over the three years, increased grain yield by 5 % and 11 %, and reduced CH 4 emissions by 22 % and 38 % in the 2nd and 3rd year, although a 6 % lower grain yield was observed in the 1st year. Biochar can increase SOCS and SOCS rate more remarkably under I AWD than I CF. Biochar coupled with I AWD obtained the highest SOCS (56.9 t C ha−1) and lowest net GWP (-23.0 t CO 2 -eq ha−1) and efficiently inhibited the negative effect of I AWD on the increase in N 2 O emissions. Moreover, compared with I CF B 0 , I CF B 20 and I AWD B 20 decreased net GWP by nearly 4 and 8 times, which was mainly attributed to a substantial increase in SOCS (48.3 and 56.9 t C ha−1) through biochar incorporation. The further decline in net GWP comparing I AWD B 20 with I CF B 20 was caused by decreased GWP under I AWD. Therefore, biochar combined I AWD offers significant benefits in mitigating net greenhouse gases emissions and promoting soil C sequestration in paddy ecosystems. • Alternate wetting and drying irrigation (I AWD) reduces CH 4 but enhances N 2 O emissions. • Biochar produced the highest C sequestration and weaken the negative impact of I AWD on N 2 O emissions. • Biochar coupled with I AWD improve C sequestration, yield, and carbon-negative emissions. [ABSTRACT FROM AUTHOR]

Organic manure application is crucial for the maintenance and improvement of soil fertility. However, it inevitably results in increased paddy CH4 emissions, restricting the use of organic manure in the rice fields. In the present study, two kinds of manures, rapidly composted manure (RCM) and non-composted manure (NCM), were investigated through a 19-week greenhouse experiment, during which the dynamics of CH4 emission, soil parameters (DOC, acetate, NH4+, NO3−, and SO42−), and communities of methanogens and methanotrophs were simultaneously measured. The results showed that NCM significantly enhanced CH4 emission, while RCM decreased CH4 emission by 65.03%; there was no significant difference with the manure-free treatment. In order to well understand the methanogenic process, the seasonal CH4 flux was divided into two periods, namely Stage 1 (before drainage) and Stage 2 (after drainage), on the basis of CH4 emission intensity. The different CH4 production abilities among the three treatments could contribute to the varied CH4 emissions at Stage 1. The much higher soil DOC concentrations were observed in the manure-amended soils (NCM- and RCM-treatments), which could correspondingly lead to the relative higher CH4 emissions compared to the control during Stage 1. Furthermore, the increased methanogenic abundance and the shifted methanogenic archaeal community characterized by the functionally stimulated growth of Methanosarcina genus were observed in the NCM-treated soils, which could consequently result in a higher CH4 emission from the NCM treatment relative to the RCM treatment. As for Stage 2, apart from the significant decrease in soil DOC, the increased contents of soil NO3− and SO42−, especially with the RCM-treated soils, were also detected following the drainage, which might retard CH4 production. The lower CH4 emission at Stage 2 could also be attributed to the vigorous aerobic CH4 oxidations, especially in the RCM-treated soils. As a support, the amount of methanotrophs revealed an increasing trend during the late rice growth period, as did the predominance of the methylotrophy of Methylophilaceae species, which showed robust co-occurrence with methanotrophs, inferring interspecies cooperation in methane oxidation.

Abstract Background Soil methanogens participate in complex interactions, which determine the community structures and functions. Studies continue to seek the coexistence patterns of soil methanogens, influencing factors and the contribution to methane (CH4) production, which are regulated primarily by species interactions, and the functional significance of these interactions. Here, methane emissions were measured in rice paddies across the Asian continent, and the complex interactions involved in coexistence patterns of methanogenic archaeal communities were represented as pairwise links in co-occurrence networks. Results The network topological properties, which were positively correlated with mean annual temperature, were the most important predictor of CH4 emissions among all the biotic and abiotic factors. The methanogenic groups involved in commonly co-occurring links among the 39 local networks contributed most to CH4 emission (53.3%), much higher than the contribution of methanogenic groups with endemic links (36.8%). The potential keystone taxa, belonging to Methanobacterium, Methanocella, Methanothrix, and Methanosarcina, possessed high linkages with the methane generation functional genes mcrA, fwdB, mtbA, and mtbC. Moreover, the commonly coexisting taxa showed a very different assembly pattern, with ~ 30% determinism and ~ 70% stochasticity. In contrast, a higher proportion of stochasticity (93~99%) characterized the assembly of endemically coexisting taxa. Conclusions These results suggest that the coexistence patterns of microbes are closely tied to their functional significance, and the potential importance of common coexistence further imply that complex networks of interactions may contribute more than species diversity to soil functions. Video abstract

The carbon cycle in lakes has been receiving great concerns and has become a hot issue. This study aimed at investigating the characteristics of Dissolved Organic Carbon (DOC) and its influence on methane emission based on continuous field sampling in a year cycle from algal-dominated zones of Lake Taihu. Results showed that the DOC with mean value of 4. 15 mg/L varied spatially due to external input and internal algal blooms. Overall, peak DOC occurred in Northwest Zone and Meiliang Bay, and temporal variations of DOC in the two zones were associated with basin precipitation, especially for Northwest Zone (R²=0. 67,P<0. 01) . It should be noted that the temporal variation of DOC in Central Zone were highly positively correlated with algal biomass mostly due to the less external input. The CH4 diffusion emission flux with mean value of 0. 083 mmol·m-2·d-1 varied greatly across zones. Algal blooms significantly stimulated the CH4 emissions via increasing DOC concentration. Overall, the algal-dominated lake was a hot spot of CH4 emission due to DOC enrichment. Considering the effects of DOC on lake CH4 emission was regulated by multiple factors related to internal metabolic activities and external loading, further studies are needed to reveal the potential control mechanism. [ABSTRACT FROM AUTHOR]

Lakes are important natural sources of atmospheric methane (CH4), which should be considered in global CH4 budget estimations. However, the CH4 emissions from lakes can be highly variable, and the emissions from the river inlet region were less studied, which seriously hamper our understanding of CH4 budget estimates of lakes. Here, field measurements from over six years (2012 to 2017) at Lake Taihu, a large eutrophic shallow lake with a complicated river network, were conducted to address the issue. Results show that the river inlet region of the lake was a hot spot of CH4 emission. The CH4 emission at the river inlet region with an annual mean value of 0.183 mmol m−2 d−1 was seven times higher than that at pelagic region (0.028 mmol m−2 d−1). Peak CH4 emission occurred in warm seasons, and the lowest in cold seasons at the pelagic region, but peak emission occurred in cold seasons at the river inlet region. The seasonal CH4 emission at the pelagic region can be explained by water temperature; however, less temperature dependency of CH4 emission at the river inlet region was found. The variability of CH4 emission was linked to pollution loadings, and CH4-rich water in the inflowing river likely sustained the large CH4 emission of river inlet region.

China's energy-related methane (CH 4) emissions account for >19.03% of global energy sector emissions, posing a significant threat to China's endeavors in mitigating climate change. However, research on the spatial-temporal patterns, drivers, and mitigation policies remains limited. This study aims to address this gap by building an innovative research framework to reveal the spatial and temporal distribution characteristics and drivers of energy-related CH 4 emissions across 30 Chinese provinces from 2010 to 2019, combining Standard Deviation Ellipsometry (SDE), Exploratory Spatial Data Analysis (ESDA), Markov Chain (MC) and Spatial Durbin Model (SDM). Key findings are: (1) The emissions exhibit a distinct clustering characteristic, with emissions clustered towards the "Northeast-Central-Northwest" direction over time. (2) There is significant positive spatial autocorrelation among emissions. As L-L agglomeration type provinces have shifted to L-H agglomeration type, the uneven distribution pattern of emissions will be intensified. (3) The emissions display path dependency, maintaining 84% steady-state probability. High-emitting provinces surrounded by medium-high or high emitters have higher downward shift probabilities. (4) The emissions have negative spillover effects on neighboring regions, suggesting the presence of competitive/substitution relationships among provinces regarding CH 4 emission sources or mitigation measures. This research enhances understanding of China's energy-related CH 4 emissions patterns and drivers, enriching the emission reduction research system. It provides new perspective for policymakers to develop adaptive policies. • CH4 emissions related to energy display spatial clustering and variability. • CH4 emissions have path-dependent characteristics with a steady-state probability of over 84%. • China's CH4 emissions have negative spillover effects on neighboring regions. • Provinces exhibit competitive/substitution relationships regarding sources of CH4 emission and mitigation measures. • GDP per capita, population density, energy production efficiency, and industrial upgrading can reduce neighbors' emissions. [ABSTRACT FROM AUTHOR]

Iron (Fe) plaque is a concentrated form of microbially available Fe oxide that coats rice plant root surfaces, representing a high density of Fe oxide and which potentially mediates paddy soil CH 4 emissions. Using a combination of methods including Fe plaque induction, isotopic labeling, pure microbial strains, and Fe oxide addition experiments, we investigated the impact of Fe plaque on methane (CH 4) emissions from paddy soils and explored the associated mechanisms underlying the influence of Fe plaque on CH 4 emissions. A 13C–CH 4 isotopic labeling experiment showed that Fe plaque did not significantly affect CH 4 oxidation and associated gene expression, whereas Fe plaque significantly enriched methanogenic archaea and their expression of genes associated with methanogenesis. Pure microbial strain and Fe oxide addition experiments showed that the enhancement of CH 4 production in the presence of Fe plaque was caused by the (semi) conductive minerals within the Fe plaque, specifically, hematite, which promoted the extracellular electron transfer between the methanogenic archaea and their syntrophic bacteria, resulting in enhancement of methanogenesis. Our results imply that the presence of Fe plaque will accelerate CH 4 emissions from paddy soils and suppressing Fe plaque has the potential to mitigate CH 4 emissions. [Display omitted] • Fe plaque increased CH 4 emissions by facilitating extracellular electron transfer. • Fe oxide promoted direct interspecies electron transfer for methanogenesis. • Limiting Fe plaque could reduce paddy soil CH 4 emissions. [ABSTRACT FROM AUTHOR]

Ammonia (NH 3) volatilization, nitrous oxide (N 2 O) emission and mineral nitrogen leaching from paddy fields are closely related to nitrogen fertilizer application. Excessive nitrogen fertilizer application has exacerbated adverse environmental effects, including global warming, atmospheric haze and groundwater pollution. Reducing the nitrogen application rate could alleviate negative environmental effects, but simultaneously brings risks of yield reduction. Biofertilizers, also known as microbial fertilizers, utilize microorganisms to improve the effectiveness of concurrent nitrogen fertilizers and have been shown to help mitigate the adverse effects of nitrogen fertilizer while ensuring rice yield. This study, which is one of the first field-scale trials of N 2 O-mitigating biofertilizers, focused on a typical paddy field in East China and investigated 9 treatments that combined mineral nitrogen fertilizer and N 2 O-mitigating biofertilizer applications to investigate yield and nitrogen loss effects over three years. The results showed reducing nitrogen combined with the N 2 O-mitigating biofertilizers increased rice yield by up to 26%, and simultaneously reduced N 2 O emission, mitigated nitrogen leaching loss, and had no significant impact on NH 3 volatilization and methane (CH 4) emissions. This is an important result and suggests that wider-scale adoption of N 2 O-mitigating biofertilizers could help reduce the environmental footprint of rice production whilst maintaining, or even improving, rice yield. • This is the first study on N 2 O-mitigating biofertilizers in paddy fields of China. • N 2 O-mitigating biofertilizers could increase rice yield. • N 2 O-mitigating biofertilizers could significantly mitigate N 2 O emission from paddy fields. • N 2 O-mitigating biofertilizers could reduce nitrogen leaching in paddy fields. [ABSTRACT FROM AUTHOR]

Perubahan iklim (PI) memerlukan perhatian yang serius, khususnya di sektor pertanian karena sector ini merupakan sumber dan kurban dari adanya PI. Oleh karena itu, perlu pendekatan dalam pengembangan pertanian untuk menghadapi PI salah satunya melalui Climarte Smart Agriculture (CSA) yang bertujuan untuk meningkatkan produktivitas, adaptasi dan mitigasi terhadap PI. Tujuan dari penelitian ini untuk mendapat informasimengenai paket teknologi ramah lingkungan di lahan sawah dalam meningkatkan produksi padi dan menurunkan emisi metana CH4. Penelitian dilaksanakan di 3 lahan milik petani (Desa Kemangi, Desa Glentengan, dan Desa Blao) kecamatan Jaken, kabupaten Pati, Jawa Tengah dengan mengintroduksikan paket teknologi ramah lingkungan budidaya padi dan membandingkan dengan cara budidaya petani konvensional. Hasil penelitian menunjukkan penelitian, Lokasi 3 desa Blao menghasilkan kombinasi emisi CH4 rendah dan menghasilkan rata-rata GKP tinggi. Lokasi 2 desa Glentengan menghasilkan emisi CH4 tinggi dan produksi rata rata GKP tinggi. Lokasi 1 desa Kemangi menghasilkan emisi CH4 rendah dan produksi GKP rendah. Emisi CH4 pada perlakuan introduksi berkisar 245-463 kg CH4/ha/musim sedangkan pada perlakuan konvensional berkisar 214-612 kg CH4/ha/musim. Hasil GKP pada perlakuan introduksi berkisar 6,12-7,72 ton/ha sedangkan pada perlakuan konvensional hasil GKP berkisar 5,58-6,58 ton/ha. Penerapan paket teknologi ramah lingkungan dapat mengurangi emisi CH4 sebesar 12,8 % serta dapat meningkatkan rata rata hasil GKP sebesar 9,8 %.

The eco-efficiency evaluation in wastewater treatment plants (WWTPs) is used to know and improve the environmental and economic efficiency of these processes, systems, products, and services. The eco-efficiency evaluations in WWTP contemplate the inputs to be minimized, the desirable results to be maximized, and the undesired results to be minimized. Data envelopment analysis (DEA) is a widely used method to evaluate the eco-efficiency of WWTPs; integrating several approaches in a single index, traditional DEA models do not take into account the uncertainty in the data. This study evaluates the eco-efficiency of a sample of Catalan WWTPs, considering the uncertainty of the data (DEA tolerance model), and it is for the first time that together with CO2, other greenhouse gas (GHG) such as CH4 and N2O are considered as part of the process outputs. GHG emissions were quantified using methods reported in the literature. Seven hundred twenty-nine eco-efficiency scores were estimated for each WWTP instead of a single score like conventional DEA models, analyzing optimistic and pessimistic scenarios. The WWTPs were classified according to the estimated eco-efficiency scores, accounting for the uncertainty in each of the scenarios, and demonstrating the changes in the performance of the WWTPs in the different scenarios. Only two WWTPs were eco-efficient in all the scenarios evaluated. This approach provides essential information to improve efficiency and innovation in the wastewater sector. [ABSTRACT FROM AUTHOR]

Global climate change, characterized by warming, is one of the major environmental problems facing mankind. Methane in greenhouse gases has huge potential for warming, and plays an important role in combating climate change, especially in the field of waste reduction It is relatively mature and has great potential for emission reduction. Therefore, it is necessary to carry out methane emission reduction research in the field of waste, and it also has important scientific significance and practical value. In this paper, the static box method is used to analyze the change of CH4 emission rate in the sealed area of the landfill, the influence of different factors on the change of emission rate is investigated, and the orthogonal test design is carried out. The results show that stable CH4 emissions from landfills are not total and continuous emissions, but local intermittent emissions. The emission rate of landfill methane in 24 h is mainly affected by overburden temperature. The degree of influence of each factor on the CH4 emission is overburden temperature> atmospheric pressure > the moisture content of the overburden > time. [ABSTRACT FROM AUTHOR]

The Zoige alpine peatlands cover approximately 4,605 km2 of the Qinghai–Tibetan Plateau and are considered to constitute the largest plateau peatland on the Eurasian continent. However, the Zoige alpine peatlands are undergoing major degradation because of human activities and climate change, which would cause uncertainty in the budget of greenhouse gases (CH4 and CO2) and carbon (C) storage in global peatlands. This study simultaneously investigates the CH4 and CO2 emission fluxes and C storage at three typical sites with respect to the peatland degradation gradient: peatland, wet meadow and dry meadow. Results show that peatland degradation would increase the CO2 emission and decrease the CH4 emission. Moreover, the average C emission fluxes were 66.05, 165.78 and 326.56 mg C m−2 hr−1 for the peatland, wet meadow and dry meadow, respectively. The C storage of the vegetation does not considerably differ among the three sampling sites. However, when compared with the peatland (1,088.17 t C ha−1), the soil organic C storage decreases by 420 and 570 t C ha−1 in case of wet and dry meadows, respectively. Although the C storage in the degraded peatlands decreases considerably, it can still represent a large capacity of C sink. Therefore, the degraded peatlands in the Zoige alpine area must be protected and restored to mitigate regional climate change. [ABSTRACT FROM AUTHOR]

We used a new underway measurement system to investigate the partial pressure of methane (CH4) in surface seawater and overlying air in the Southern Ocean from late November 2012 to mid-February 2013. The underway system consisted of a cavity ring-down spectroscopy analyser and a shower-head type equilibrator. The monthly mean atmospheric CH4 mixing ratios obtained agreed well (within 5 ppb) with those recorded at onshore baseline stations. CH4 saturation ratios (SR, %), defined as CH4 concentration in seawater divided by CH4 concentration equilibrated with atmospheric CH4, varied between 85 and 185%; most of the ratios we calculated indicated supersaturation, except for those from south of the Southern limit of Upper Circumpolar Deep Water. SR was higher at the lower latitudes, including coastal areas north of the Sub-Antarctic Front, but decreased gradually and monotonously between the Sub-Antarctic Front and the Upper Circumpolar Deep Water. At high latitudes south of the Polar Front, SR decreased to below 100% due to the effects of upwelling and vertical mixing. We found a strong linear correlation between SR and apparent oxygen utilisation (AOU) south of the Polar Front. Observed SR decreased with increasing AOU and reached 85% at high AOU (41 µmol kg−1) and low temperature (–1.8 °C). On the basis of the linear relationship between SR and AOU, we evaluated the climatological sea–air flux of CH4 from December to February for the entire Southern Ocean south of 50°S: Sea–air CH4 emission was estimated to be 0.027 Tg yr−1 in December, 0.04 Tg yr−1 in January, and 0.019 Tg yr−1 in February.

Forest soils are the most important terrestrial sink of atmospheric methane (CH4). Climatic, soil and anthropogenic drivers affect CH4 fluxes, but it is poorly known the relative weight of each driver and whether all drivers have similar effects across forest biomes. We compiled a database of 478 in situ estimations of CH4 fluxes in forest soils from 191 peer‐reviewed studies. All forest biomes (boreal, temperate, tropical and subtropical) but savannahs act on average as CH4 sinks, which presented positive fluxes in 65% of the sites. Mixed effects models showed that combined climatic and edaphic variables had the best support, but anthropogenic factors did not have a significant effect on CH4 fluxes at global scale. This model explained only 19% of the variance in soil CH4 flux which decreased with declines in precipitation and increases in temperature, and with increases in soil organic carbon, bulk density and soil acidification. The effects of these drivers were inconsistent across biomes, increasing the model explanation of observed variance to 34% when the drivers have a different slope for each biome. Despite this limited explanatory value which could be related to the use of soil variables calculated at coarse scale (~1 km), our study shows that soil CH4 fluxes in forests are determined by different environmental variables in different biomes. The most sensitive system to all studied drivers were the temperate forests, while boreal forests were insensitive to climatic variables, but highly sensitive to edaphic factors. Subtropical forests and savannahs responded similarly to climatic variables, but differed in their response to soil factors. Our results suggest that the increase in temperature predicted in the framework of climate change would promote CH4 emission (or reduce CH4 sink) in subtropical and savannah forests, have no influence in boreal and temperate forests and promote uptake in tropical forests. [ABSTRACT FROM AUTHOR]