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Significance A major uncertainty in the sources of atmospheric methane is the role of geologic seepage from petroleum-bearing sedimentary basins. Hydrocarbon seeps located onshore, shallow offshore, and coastal areas can play a major role. Methane released by deep ocean seeps typically does not reach the atmosphere. Here, we provide evidence for a single, large, and sudden expulsion of methane from a deep‐water reservoir during the Pliocene. We use geophysical evidence and fluid-flow modeling to estimate that this single event would have amounted to ∼10% of present‐day annual natural methane emissions. Although no ultraseepage events, such as this one, have been documented in modern times, the relatively common geologic circumstances of this type of event suggest that they are not exceptional., Geologic hydrocarbon seepage is considered to be the dominant natural source of atmospheric methane in terrestrial and shallow‐water areas; in deep‐water areas, in contrast, hydrocarbon seepage is expected to have no atmospheric impact because the gas is typically consumed throughout the water column. Here, we present evidence for a sudden expulsion of a reservoir‐size quantity of methane from a deep‐water seep during the Pliocene, resulting from natural reservoir overpressure. Combining three-dimensional seismic data, borehole data and fluid‐flow modeling, we estimate that 18–27 of the 23–31 Tg of methane released at the seafloor could have reached the atmosphere over 39–241 days. This emission is ∼10% and ∼28% of present‐day, annual natural and petroleum‐industry methane emissions, respectively. While no such ultraseepage events have been documented in modern times and their frequency is unknown, seismic data suggest they were not rare in the past and may potentially occur at present in critically pressurized reservoirs. This neglected phenomenon can influence decadal changes in atmospheric methane.

BACKGROUND Information about the nutritive value, dry matter (DM) digestibility, and methane (CH4 ) emission potential of grass species is required for their optimal utilization in ruminant rations. The present study was designed: (i) to quantify the nutrient profile, mineral composition and in vitro dry matter digestibility (IVDMD) of winter grass species commonly available in northern Pakistan; and (ii) to measure the in vitro gas production (IVGP) and CH4 emission of the grass species during 72 h in vitro ruminal fermentation. Seven grass species, namely, Cenchrus ciliaris, Setaria anceps, Panicum antidotale, P. maximum, Pennisetum purpureum, Pennisetum orientale, and Atriplex lentiformis were assessed. RESULTS A high level of variability (P

Globally, tropical forests are assumed to be an important source of atmospheric nitrous oxide (N2O) and sink for methane (CH4). Yet, although the Congo Basin comprises the second largest tropical forest and is considered the most pristine large basin left on Earth, in situ N2O and CH4 flux measurements are scarce. Here, we provide multi-year data derived from on-ground soil flux (n = 1558) and riverine dissolved gas concentration (n = 332) measurements spanning montane, swamp, and lowland forests. Each forest type core monitoring site was sampled at least for one hydrological year between 2016 - 2020 at a frequency of 7-14 days. We estimate a terrestrial CH4 uptake (in kg CH4-C ha−1 yr−1) for montane (−4.28) and lowland forests (−3.52) and a massive CH4 release from swamp forests (non-inundated 2.68; inundated 341). All investigated forest types were a N2O source (except for inundated swamp forest) with 0.93, 1.56, 3.5, and −0.19 kg N2O-N ha−1 yr−1 for montane, lowland, non-inundated swamp, and inundated swamp forests, respectively., Nature Communications, 13, ISSN:2041-1723

It is known that nitrate inhibits ruminal methanogenesis, mainly through competition with hydrogenotrophic methanogens for available hydrogen (H2) and also through toxic effects on the methanogens. However, there is limited knowledge about its effects on the others members of ruminal microbiota and their metabolites. In this study, we investigated the effects of dietary nitrate inclusion on enteric methane (CH4) emission, temporal changes in ruminal microbiota, and fermentation in Holstein calves. Eighteen animals were maintained in individual pens for 45 d. Animals were randomly allocated to either a control (CTR) or nitrate (NIT, containing 15 g of calcium nitrate/kg dry matter) diets. Methane emissions were estimated using the sulfur hexafluoride (SF6) tracer method. Ruminal microbiota changes and ruminal fermentation were evaluated at 0, 4, and 8 h post-feeding. In this study, feed dry matter intake (DMI) did not differ between dietary treatments (P > 0.05). Diets containing NIT reduced CH4 emissions by 27% (g/d) and yield by 21% (g/kg DMI) compared to the CTR (P < 0.05). The pH values and total volatile fatty acids (VFA) concentration did not differ between dietary treatments (P > 0.05) but differed with time, and post-feeding (P < 0.05). Increases in the concentrations of ruminal ammonia nitrogen (NH3–N) and acetate were observed, whereas propionate decreased at 4 h post-feeding with the NIT diet (P < 0.05). Feeding the NIT diet reduced the populations of total bacteria, total methanogens, Ruminococcus albus and Ruminococcus flavefaciens, and the abundance of Succiniclasticum, Coprococcus, Treponema, Shuttlewortia, Succinivibrio, Sharpea, Pseudobutyrivibrio, and Selenomona (P < 0.05); whereas, the population of total fungi, protozoa, Fibrobacter succinogenes, Atopobium and Erysipelotrichaceae L7A_E11 increased (P < 0.05). In conclusion, feeding nitrate reduces enteric CH4 emissions and the methanogens population, whereas it decreases the propionate concentration and the abundance of bacteria involved in the succinate and acrylate pathways. Despite the altered fermentation profile and ruminal microbiota, DMI was not influenced by dietary nitrate. These findings suggest that nitrate has a predominantly direct effect on the reduction of methanogenesis and propionate synthesis. Instituto de Patobiología Fil: Ortiz Chura, Abimael. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Patobiología; Argentina Fil: Ortiz Chura, Abimael. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Fil: Gere, José. Universidad Tecnológica Nacional. División Investigación y Desarrollo de Ingenierías; Argentina Fil: Gere, José. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Marcoppido, Gisela Ariana. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Patobiología; Argentina Fil: Marcoppido, Gisela Ariana. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Depetris, Gustavo. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Balcarce; Argentina Fil: Cravero, Silvio Lorenzo Pedro. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Agrobiotecnología y Biología Molecular; Argentina Fil: Cravero, Silvio Lorenzo Pedro. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Faverin, Claudia. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Balcarce; Argentina Fil: Pinares-Patiño, Cesar. Lincoln University. The Agribusiness Group; Nueva Zelanda Fil: Cataldi, Angel Adrian. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Agrobiotecnología y Biología Molecular; Argentina Fil: Cataldi, Angel Adrian. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Ceron Cucchi, Maria Esperanza. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Patobiología; Argentina Fil: Ceron Cucchi, Maria Esperanza. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

In the Marche Region (Central Italy), the residual municipal waste (RMW) is commonly processed in mechanical biological treatment (MBT) systems. In these systems, following a first mechanical selection, the undersize organic fraction from RMW (us-OFRMW) undergoes a partial aerobic biological treatment before being landfilled as a biostabilised fraction (bios-OFRMW) without dedicated energy or material recovery. Alternative us-OFRMW management scenarios have been elaborated for this region, at both present (reference year 2019) and future (reference year 2035) time bases. In the first scenario, the potential bioenergy recovery through anaerobic digestion (AD) from the us-OFRMW was evaluated. The second scenario aimed at evaluating the residual methane generation expected from the bios-OFRMW once landfilled, thus contributing also to the potential environmental impact connected with landfill gas (LFG) diffuse emissions from the regional landfills. The diversion to AD, at the present time, would allow a potential bioenergy recovery from the us-OFRMW equal to 4.35 MWel, while the alternative scenario involves greenhouse gas (GHG) emissions equal to 195 kg CO2 eq. per ton of deposited bios-OFRMW. In the future, the decreased amount of the us-OFRMW addressed to AD would still contribute with a potential bioenergy recovery of 3.47 MWel.

This study aimed to evaluate in vitro and in vivo dietary supplementation with different levels of natural or nano-zeolite forms on rumen fermentation patterns and nutrient digestibility. In the in vitro experiment, a basal diet (50% concentrate: 50% forage) was incubated without additives (control) and with natural zeolite (10, 20, 30 g/kg DM) or nano-zeolite (0.2, 0.3, 0.4, 0.5, 1.0 g/kg DM) for 24 h to assess their effect on ruminal fermentation, feed degradability, and gas and methane production using a semi-automatic system of in vitro gas production (GP). The most effective doses obtained from the in vitro experiment were evaluated in vivo using 30 Barki goats (26 ± 0.9 SE kg body weight). Goats were allocated into three dietary treatments (n = 10/treatment) as follows: control (basal diet without any supplementations), natural zeolite (20 g/kg DM diet), and nano-zeolite (0.40 g/kg DM diet). The in vitro results revealed that only the nano-zeolite supplementation form quadratically (p= 0.004) increased GP, and the level of 0.5 g/kg DM had the highest GP value compared to the control. Both zeolite forms affected the CH4 production, linear, and quadratic reductions (p &lt, 0.05) in CH4 (mL/g DM), consistent with linear increases in truly degraded organic matter (TDOM) (p = 0.09), and propionate molar proportions (p = 0.007) were observed by nano zeolite treatment, while the natural form of zeolite resulted in a linear CH4 reduction consistent with a linear decrease (p = 0.004) in NH3-N, linear increases in TDOM (p = 0.09), and propionate molar proportions (p = 0.004). Results of the in vivo experiment demonstrated that the nutrient digestibility was similar among all treatments. Nano zeolite enhanced (p &lt, 0.05) the total short-chain fatty acids and butyrate concentrations, while both zeolite forms decreased (p &lt, 0.001) NH3-N compared to the control. These results suggested that both zeolite supplementation forms favorably modified the rumen fermentation in different patterns.

Methane (CH4) emission from paddy rice fields is a global concern; however, engineering plant spacing can decrease CH4 emission. Due to this, field research was conducted to measure CH4 emissions from rice fields planted using jarwo 2:1 spacing, which has a 25 × 12.5 cm and 50 cm for the plant-free area (PFA), compared to tegel, which has a spacing of 25 × 25 cm. Each field was treated with organic fertilizer (mixture of cow manure and neem compost in a ratio of 1:1) with one of four doses: 0, 3, 6 and 9 tons/ha. The results showed that chemical properties such as soluble-Fe, soil organic matter (SOM), soil acidity (pH), and redox potential (Eh) were significantly correlated with CH4 emissions (0.52***, 0.47**, 0.36*, and -0.27* respectively). Jarwo 2:1 had lower CH4 emissions than tegel on all doses of fertilizer. The most efficient dose of fertilizer was 3 tons/ha applied jarwo 2:1 because it was able to produce rice up to 12 tons/ha with CH4 emissions of only 34 kg/ha/season, while CH4 emissions in tegel was 39 kg/ha/season. It is concluded that jarwo 2:1 with 3 tons/ha organic fertilizers can be recommended to farmers because it produces lower CH4 emissions and higher rice yield.

Objective This study was conducted to evaluate the effects of Ecklonia stolonifera (E. stolonifera) extract addition on in vitro ruminal fermentation characteristics, methanogenesis and microbial populations. Methods One cannulated Holstein cow (450±30 kg) consuming timothy hay and a commercial concentrate (60:40, w/w) twice daily (09:00 and 17:00) at 2% of body weight with free access to water and mineral block were used as rumen fluid donors. In vitro fermentation experiment, with timothy hay as substrate, was conducted for up to 72 h, with E. stolonifera extract added to achieve final concentration 1%, 3%, and 5% on timothy hay basis. Results Administration of E. stolonifera extract to a ruminant fluid-artificial saliva mixture in vitro increased the total gas production. Unexpectedly, E. stolonifera extracts appeared to increase both methane emissions and hydrogen production, which is contrasts with previous observations with brown algae extracts used under in vitro fermentation conditions. Interestingly, real-time polymerase chain reaction indicated that as compared with the untreated control the ciliate-associated methanogen and Fibrobacter succinogenes populations decreased, whereas the Ruminococcus flavefaciens population increased as a result of E. stolonifera extract supplementation. Conclusion E. stolonifera showed no detrimental effect on rumen fermentation characteristics and microbial population. Through these results E. stolonifera has potential as a viable feed supplement to ruminants.

[EN] The objective of this experiment was to study the effects of substituting alfalfa with orange leaves on energy, nitrogen and carbon balance, methane emission, and milk performance in dairy goats. Ten Murciano-Granadina dairy goats in mid lactation (43.5 +/- 3.59 kg of body weight [BW]) were selected in a crossover design experiment, where each goat received two treatments in 2 periods. One group of five goats was fed a mixed ration with 450 g of pelleted alfalfa and 550 g of pelleted concentrate/kg of dry matter (ALF diet), and the other diet replaced alfalfa with orange leaves (ORG diet). Inclusion of ORG than ALF diet reduced (P = 0.041) dry matter intake. The metabolizable energy intake was identical between treatments (901 kJ/kg of BW0.75, on average) and, the efficiency of metabolizable energy for milk production was 0.73. Retention of energy was lower (P = 0.001) in ORG diet than ALF diet. Carbon and nitrogen intake (P = 0.022 and P = 0.004, respectively) was greater for diet ALF than ORG, with no differences in milk carbon and nitrogen. The ORG diet reduced (P = 0.037) milk fat 3 g/kg, and CH4 (P = 0.001) 6 g/d. One of the milk fatty acids positively correlated with CH4 production was C16:0; it was greater (P < 0.05) in ALF than ORG diet. When CH4 was expressed over OM digestibility and milk basis, differences were preserved. Results suggest that orange leaves are effective in reducing CH4 emission without detrimental effect on nutrients balance and milk yield., This study was supported by HELIOTEC S.L., La Vall d'Uixo, Castellon de la Plana, Valencia, Spain, though LIFE Ecocitric Project and, LIFE2016/CCM/ES/000088 LOW CARBON FEED.

This study investigated the potential benefits of using biochar granules as an alternative to the standard carbon felt anode in microbial fuel cells (MFC). Single-chamber cylindrical air-cathode MFCs were filled with sandy loam soil. Rice plants (Oryza sativa L.) cultivar FARO 44 were grown in plant MFCs (PMFCs). The performance of PMFC was compared with that of the soil MFC (SMFC) lacking rice plants. During 125 days of operation, the highest power density was 41.41 mW m−2 of cathode area and it was observed in PMFC with carbon felt anode (PMFC-RCF). In PMFC with biochar anode (PMFC-RBC), the power density was lower, and the highest value recorded was 11.11 mW m−2. On average (over the 125 days), PMFCs and SMFCs equipped with biochar anodes produced less bioelectricity, 16 and 27 percent, respectively, of those equipped with carbon felt anodes. On the other hand, methane emissions from PMFCS and SMFCs equipped with biochar anodes were reduced by 39% and 19%, respectively, when compared to those with carbon felt anodes. It was also observed that the total plant biomass was not significantly affected by the types of anode used. More studies are required to further improve the bioelectricity production of MFCs incorporated with biochar knowing that they have the benefit of reducing methane emission without decreasing the plant biomass yield.

This In Vitro study was conducted to investigate the impact of plant-bioactives extract (PE), a combination of garlic powder and bitter orange extract, on methane production, rumen fermentation, and digestibility in different feeding models. The dietary treatments were 1000 g grass/kg ration + 0 g concentrate/kg ration (100:0), 80:20, 60:40, 40:60, and 20:80. The PE was supplemented at 200 g/kg of the feed. Each group consisted of 6 replicates. The experiment was performed as an In Vitro batch culture for 24 h at 39 °C. This procedure was repeated in three consecutive runs. The results of this experiment showed that supplementation with PE strongly reduced methane production in all kinds of feeding models (p &lt, 0.001). Its efficacy in reducing methane/digestible dry matter was 44% in the 100:0 diet, and this reduction power increased up to a 69.2% with the inclusion of concentrate in the 20:80 diet. The PE application significantly increased gas and carbon dioxide production and the concentration of ammonia-nitrogen, but decreased the pH (p &lt, 0.001). In contrast, it did not interfere with organic matter and fiber digestibility. Supplementation with PE was effective in altering rumen fermentation toward less acetate and more propionate and butyrate (p &lt, 0.001). Additionally, it improved the production of total volatile fatty acids in all feeding models (p &lt, 0.001). In conclusion, the PE combination showed effective methane reduction by improving rumen fermentation characteristics without exhibiting adverse effects on fiber digestibility. Thus, PE could be used with all kinds of feeding models to effectively mitigate methane emissions from ruminants.

BackgroundLactating dairy cows are the greatest livestock contributor of methane, a major global greenhouse gas (GHG). However, good feeding management with adequate mineral intake can offers an effective approach to maintaining high levels of milk production and the health of dairy cows over the entire course of lactation, while also helping to reduce methane emission. The study described here investigated the plasma concentrations of both macroelements (Ca, Na, K, Mg, P) and microelements (Zn, Cu, Fe, Mn), as well as enteric methane emission and milk composition in high-yielding dairy cows in different lactation periods. The experiment was performed on Holstein–Friesian dairy cows with the average milk yield of 41 (± 9) L/day in a Polish commercial farm with modern dairy systems. A total of thirty high-yielding dairy cows were randomly assigned into three groups differing by lactation stage: early stage (Early, days 25–100), middle stage (Middle, days 101–250), and late stage (Late, day 250 and later). Dietary treatment for all cows was a total mixture ration (TMR) with maize and alfalfa silage the main forage components.ResultsThe greatest milk yield and methane production were recorded in early-stage lactating cows, but the greatest methane intensity per kg of corrected milk was recorded in the late stage of lactation. Plasma concentrations of macroelements and microelements did not differ by lactation stages, but increased plasma concentrations of Zn and Fe and decreased plasma levels of Mg were noted during lactation. A positive correlation was found between plasma levels of Mg and other macroelements (Ca, Na, K), and between the concentrations of Fe and Zn, P in plasma, but no correlation between methane emission and mineral status was detected in the different lactation stages.ConclusionsOur results showed different mineral requirements and enteric methane emissions in each lactation stage. The feeding strategy and mineral utilization were adequate to maintain the health, mineral status, and milk production of the Holstein cows during the entire lactation period, and suggest an effective way of reducing methane emission.

This study estimated the effect of essential fatty acid (FA) supplementation on fermentation indices, greenhouse gases, microbes, and FA profiles in the rumen. The treatments used pure FAs consisting of C18:2n-6 FA (LA), C18:3n-3 FA (LNA), or a mixture of these FAs at 1:1 ratio (Combo). In vitro rumen incubation was performed in 50 mL glass serum bottles containing 2 mg of pure FAs, 15 mL of rumen buffer (rumen fluid+anaerobe culture medium = 1:2), and 150 mg of synthetic diet (411 g cellulose, 411 g starch, and 178 g casein/kg dry matter) at 39°C for 8 h with five replications and three blanks. In rumen fermentation indices, LA exhibited highest (P < 0.05) ammonia-N and total gas volume after 8 h of incubation. Furthermore, LA presented lower (P < 0.05) pH with higher (P < 0.05) total volatile fatty acid (P = 0.034) than Combo, while LNA was not different compared with those in the other treatments. Additionally, Combo produced highest (P < 0.05) CO2 with lowest (P < 0.05) CH4. In the early hours of incubation, LA improved (P < 0.005) Fibrobacter succinogenes and Ruminococcus flavefaciens, while LNA improved (P < 0.005) Ruminococcus albus. After 8 h of incubation, LNA had lower (P < 0.05) methanogenic archaea than LA and Combo but had higher (P < 0.05) rumen ciliates than LA. R. albus was higher (P < 0.05) in LA than in LNA and Combo. It was observed that the rate of biohydrogenation of n-6 and n-3 FAs was comparatively lowest (P < 0.05) in Combo, characterized by higher C18:2n-6 and/or C18:3n-3 FA and polyunsaturated FA (PUFA) concentrations with lower (P < 0.05) concentrations of C18:0 and saturated FA and the ratio of saturated FAs to PUFAs. Therefore, this study concluded that dietary C18:2n-6 could improve populations of fibrolytic bacteria and rumen fermentation indices, but dietary mixture of pure C18:2n-6 and C18:3n-3 is recommended because it is effective in reducing enteric methane emissions and resisting biohydrogenation in the rumen with less effect on rumen microbes.

Methane mitigation strategies have a two-sided benefit for both environment and efficient livestock production. This preliminary short-term in vitro trial using Mootral (garlic and citrus extracts), a novel natural feed supplement, was conducted to evaluate its efficacy on rumen fermentation characteristics, methane production, and the bacterial and archaeal community. The experiment was performed as a batch culture using rumen fluid collected from sheep, and Mootral was supplemented in three concentrations: 0% (Control), 10%, and 20% of the substrate (50% Grass:50% Concentrate). The rumen fermentation data and alpha diversity of microbial community were analyzed by ordinary one-way analysis of variance. The relative abundance and statistical significance of families and operational taxonomic units (OTUs) among the groups were compared by Kruskal–Wallis H test using Calypso software. After 24-h incubation at 39°C, Mootral in a dose-dependent manner improved the production of total volatile fatty acids and propionate while it reduced the acetate proportion and acetate/propionate ratio. The total produced gas was two times higher in the Mootral-supplemented groups than control (P < 0.01), while the proportion of methane in the produced gas was reduced by 22% (P < 0.05) and 54% (P < 0.01) for 10 and 20% Mootral, respectively. Mootral did not change pH, digestibility, and ammonia-nitrogen. Microbial community analyses showed that Mootral effectively changed the ruminal microbiome. The bacterial community showed an increase of the relative abundance of the propionate-producing family such as Prevotellaceae (P = 0.014) and Veillonellaceae (P = 0.030), while there was a decrease in the relative abundance of some hydrogen-producing bacteria by Mootral supplementation. In the archaeal community, Methanobacteriaceae was decreased by Mootral supplementation compared with control (P = 0.032), while the Methanomassiliicoccaceae family increased in a dose-dependent effect (P = 0.038). The results of the study showed the efficacy of the new mixture to alter the ruminal microbial community, produce more propionate, and reduce microbial groups associated with methane production, thus suggesting that Mootral is a promising natural mixture for methane reduction from ruminants.

Groundwater for drinking water production may contain dissolved methane (CH4) at variable concentrations. Most of this important greenhouse gas is often vented to the atmosphere during primary aeration and gas stripping processes at drinking water treatment plants (DWTPs). However, limited information exists regarding emission and fate of methane at many groundwater-fed DWTPs. This study estimates emission of methane from 1,004 DWTPs in Denmark and includes data from 3,068 groundwater wells. The fate of methane and occurrence of methane oxidizing bacteria in DWTPs was examined, including the potential role in ammonia removal. Methane emission from Danish DWTPs was estimated to be 1.38–2.95 × 10−4 Tg CH4/y which corresponds to 0.05–0.11% of the national anthropogenic methane emission. Trace levels of methane remained in the drinking water after primary aeration and entered the sand filters as a potential microbial substrate. Methanotrophic bacteria and active methane oxidation was always detected in the sand filters at groundwater-fed DWTPs. Methanotrophic consortia isolated from DWTP sandfilters were inoculated into laboratory-scale sand filters and the activity confirmed that methanotrophic consortia can play a role in the removal of ammonia via assimilation and co-oxidation. This suggests a potential for facilitating the removal of inorganic constituents from drinking water using methane as a co-substrate.

The safety of the gas transmission infrastructure is one of the main concerns for infrastructure operating companies. Common gas pipelines’ tightness control is tedious and time-consuming. The development of new methods is highly desirable. This paper focuses on the applications of air-borne methods for inspections of the natural gas pipelines. The main goal of this study is to test an unmanned aerial vehicle (UAV), equipped with a remote sensing methane detector, for natural gas leak detection from the pipeline network. Many studies of the use of the UAV with laser detectors have been presented in the literature. These studies include experiments mainly on the artificial methane sources simulating gas leaks. This study concerns the experiments on a real leakage of natural gas from a pipeline. The vehicle at first monitored the artificial source of methane to determine conditions for further experiments. Then the experiments on the selected section of the natural gas pipelines were conducted. The measurement data, along with spatial coordinates, were collected and analyzed using machine learning methods. The analysis enabled the identification of groups of spatially correlated regions which have increased methane concentrations. Investigations on the flight altitude influence on the accuracy of measurements were also carried out. A range of between 4 m and 15 m was depicted as optimal for data collection in the natural gas pipeline inspections. However, the results from the field experiments showed that areas with increased methane concentrations are significantly more difficult to identify, though they are still noticeable. The experiments also indicate that the lower altitudes of the UAV flights should be chosen. The results showed that UAV monitoring can be used as a tool for the preliminary selection of potentially untight gas pipeline sections.

[EN] The aim of this study was to evaluate the effects of incorporating rice straw and orange leaves into the diets for goats. Ten Murciano-Granadina goats at mid lactation weighing 45 +/- 0.3 kg were used in a crossover design. Two isoproteic and isoenergetic diets (180 g/kg DM and 17 MJ/kg DM, respectively) with alfalfa hay as forage source (33% of DM) were fed. A control diet (CON) incorporated barley as energy source and soy hulls as fiber component. The experimental diet (ORG) replaced barley and soy hulls with orange leaves (19% on DM basis), rice straw (12%, on DM basis) and soya oil (2%). Peas and horsebeans were the protein source in both diets. Each goat received the 2 treatments in 2 periods. Goats were fed the experimental diets and after 14 d on their respective treatments moved to individual metabolism cages for another 7 d. Subsequently, feed intake, total fecal and urine output and milk yield were recorded daily over the first 5 d. During the next 2 d ruminal fluid and blood samples were collected, and then individual gas-exchange measurements were recorded by a mobile open-circuit indirect calorimetry system using a head box. No differences in dry matter intake were detected, and apparent total-tract digestibility was greater in CON than ORG. Efficiency of metabolizable energy intake for milk and maintenance also was lower in response to ORG (0.65 vs. 0.63), with energy balance being negative (-12 kJ/kg of BW0.75) due to mobilization of fat (-16 g/animal vs. 68 g/animal for ORG and CON, respectively). Although actual milk yield was lower in goats fed ORG (2.32 vs. 2.06 kg/d, respectively), energy-corrected milk did not differ (2.81 kg/d on average). In terms of milk quality, milk fat content, and concentrations of monounsaturated (18.54 vs. 11.55 g/100 g milk fat) and polyunsaturated fatty acids (5.75 vs. 3.99 g/100 g milk fat) were greater in goats fed ORG. Based on various indices, the milk produced by ORG would be less atherogenic and thrombogenic than CON milk. Compared with CON, enteric CH4 emission was lower due to feeding ORG (reduction of 38 g CH4/kg milk fat). Data suggest that greater fat mobilization in goats fed ORG might have been due to the apparent lack of synchrony between degradable protein and carbohydrate and the lipogenic nutrients associated with the lower cereal content of the ORG diet. Thus, goats fed ORG seemed to rely more on fat depots to help meet energy requirements and reach optimal performance. As such, the lower content of glucogenic nutrients in ORG did not favor body fat deposition and partitioning of ME into body tissue. Overall, responses in terms of CH4 emissions and milk quality suggest that inclusion of rice straw and orange leaves in diets for small ruminants could be a valuable alternative to reuse, recycle and revalue agricultural by-products., This study was supported by LIFE Project, Spain (ref. LIFE2016/CCM/ES/000088 LOW CARBON FEED), funded by the EU Commission (Brussels, Belgium). The authors have not stated any conflicts of interest.

Background Methane emission by ruminants has contributed considerably to the global warming and understanding the genomic architecture of methane production may help livestock producers to reduce the methane emission from the livestock production system. The goal of our study was to identify genomic regions affecting the predicted methane emission (PME) from volatile fatty acids (VFAs) indicators and VFA traits using imputed whole-genome sequence data in Iranian Holstein cattle. Results Based on the significant-association threshold (p − 8), 33 single nucleotide polymorphisms (SNPs) were detected for PME per kg milk (n = 2), PME per kg fat (n = 14), and valeric acid (n = 17). Besides, 69 genes were identified for valeric acid (n = 18), PME per kg milk (n = 4) and PME per kg fat (n = 47) that were located within 1 Mb of significant SNPs. Based on the gene ontology (GO) term analysis, six promising candidate genes were significantly clustered in organelle organization (GO:0004984, p = 3.9 × 10− 2) for valeric acid, and 17 candidate genes significantly clustered in olfactory receptors activity (GO:0004984, p = 4 × 10− 10) for PME traits. Annotation results revealed 31 quantitative trait loci (QTLs) for milk yield and its components, body weight, and residual feed intake within 1 Mb of significant SNPs. Conclusions Our results identified 33 SNPs associated with PME and valeric acid traits, as well as 17 olfactory receptors activity genes for PME traits related to feed intake and preference. Identified SNPs were close to 31 QTLs for milk yield and its components, body weight, and residual feed intake traits. In addition, these traits had high correlations with PME trait. Overall, our findings suggest that marker-assisted and genomic selection could be used to improve the difficult and expensive-to-measure phenotypes such as PME. Moreover, prediction of methane emission by VFA indicators could be useful for increasing the size of reference population required in genome-wide association studies and genomic selection.

The aim of our study was to estimate methane (CH4) emissions from a dairy cattle farm using a computer application. Emissions of CH4 in the air were forecast for a representative dairy farm raising Holstein-Friesian cows. The cowshed was equipped with a mechanical forced ventilation system with a centrally located ventilation duct. The volume of emissions from the emitter was established, taking into account meteorological conditions. For one year of operation of the emitter, the average annual emission was 1.301 kg/h. The maximum emission of CH4 was estimated at 3.51 kg/h. These data can be helpful in estimating the environmental burden of a dairy farm and in determining the role of ruminants in global warming.

This study focuses on the geochemical features of the presently discharging thermal and cold springs and on paleofluids from the upstream portion of the Reno river basin (Alto Reno; central–northern Italy). The aim is investigating the primary sources of the modern and fossil fluids and the interactions between deep and shallow aquifers. Paleofluids are from fluid inclusions hosted within euhedral and hopper quartz crystals and consist of a two-phase, liquid–vapor aqueous fluid and a unary CH4 fluid. The aqueous inclusions have constant phase ratios and a calculated salinity of ~ 1.5 wt% NaCleq. They homogenize by bubble disappearance at 100–200 °C, whereas the estimated entrapment depth is ~ 3–5.5 km. The paleofluids likely represent the vestiges of the deep and hot, CH4-rich, Na+–Cl− fluids produced by the interaction between meteoric waters and Triassic and Miocene formations. The modern Na+–Cl−(HCO3−) thermal waters originate from meteoric waters infiltrating SW of the study area, at elevation > 800 m a.s.l., circulating within both the Triassic evaporites and the overlying Miocene turbiditic formations, where salt dissolution/precipitation, sulfate reduction, and production of thermogenic CH4 occur. The equilibrium temperature of the deep fluid source is ~ 170 °C, corresponding to > 5 km depth. Cold springs are Ca2+–HCO3− type and show low amounts of biogenic CO2 and CH4 with no inputs of deep-originated fluids excepting in the immediate surroundings of the thermal area, confirming the lack of significant hydraulic connection between shallow and deep aquifers. We propose a genetic link between the quartz-hosted paleofluid and the thermal waters present in the area.

Methane (CH4) emissions represent a worldwide problem due to their direct involvement in atmospheric warming and climate change. Ruminants are among the major players in the global scenario of CH4 emissions, and CH4 emissions are a problem for feed efficiency since enteric CH4 is eructed to the detriment of milk and meat production. The collection of CH4 phenotypes at the population level is still hampered by costly and time-demanding techniques. In the present study, a laser methane detector was used to assess repeatability and reproducibility of CH4 phenotypes, including mean and aggregate of CH4 records, slope of the linear equation modelling the aggregate function, and mean and number of CH4 peak records. Five repeated measurements were performed in a commercial farm on three Simmental heifers, and the same protocol was repeated over a period of three days. Methane emission phenotypes expressed as parts per million per linear meter (ppm &times, m) were not normally distributed and, thus, they were log-transformed to reach normality. Repeatability and reproducibility were calculated as the relative standard deviation of five measurements within the same day and 15 measurements across three days, respectively. All phenotypes showed higher repeatability and reproducibility for log-transformed data compared with data expressed as ppm &times, m. The linear equation modelling the aggregate function highlighted a very high coefficient of determination (&ge, 0.99), which suggests that daily CH4 emissions might be derived using this approach. The number of CH4 peaks resulted as particularly diverse across animals and therefore it is a potential candidate to discriminate between high and low emitting animals. Results of this study suggest that laser methane detector is a promising tool to measure bovine CH4 emissions in field conditions.

We employed a global high-resolution inverse model to optimize the CH4 emission using Greenhouse gas Observing Satellite (GOSAT) and surface observation data for a period from 2011−2017 for the two main source categories of anthropogenic and natural emissions. We used the Emission Database for Global Atmospheric Research (EDGAR v4.3.2) for anthropogenic methane emission and scaled them by country to match the national inventories reported to the United Nations Framework Convention on Climate Change (UNFCCC). Wetland and soil sink prior fluxes were simulated using the Vegetation Integrative Simulator of Trace gases (VISIT) model. Biomass burning prior fluxes were provided by the Global Fire Assimilation System (GFAS). We estimated a global total anthropogenic and natural methane emissions of 340.9 Tg CH4 yr−1 and 232.5 Tg CH4 yr−1, respectively. Country-scale analysis of the estimated anthropogenic emissions showed that all the top-emitting countries showed differences with their respective inventories to be within the uncertainty range of the inventories, confirming that the posterior anthropogenic emissions did not deviate from nationally reported values. Large countries, such as China, Russia, and the United States, had the mean estimated emission of 45.7 ± 8.6, 31.9 ± 7.8, and 29.8 ± 7.8 Tg CH4 yr−1, respectively. For natural wetland emissions, we estimated large emissions for Brazil (39.8 ± 12.4 Tg CH4 yr−1), the United States (25.9 ± 8.3 Tg CH4 yr−1), Russia (13.2 ± 9.3 Tg CH4 yr−1), India (12.3 ± 6.4 Tg CH4 yr−1), and Canada (12.2 ± 5.1 Tg CH4 yr−1). In both emission categories, the major emitting countries all had the model corrections to emissions within the uncertainty range of inventories. The advantages of the approach used in this study were: (1) use of high-resolution transport, useful for simulations near emission hotspots, (2) prior anthropogenic emissions adjusted to the UNFCCC reports, (3) combining surface and satellite observations, which improves the estimation of both natural and anthropogenic methane emissions over spatial scale of countries.

Resumo O metano é o segundo gás de efeito estufa e sua concentração na atmosfera aumentou 259% desde 1750. A média global da fração molar de CH4 atingiu um novo recorde de 1813 ± 2 ppb em 2011. Este trabalho objetiva quantificar a concentração e fluxo de metano no perfil vertical da floresta primária tropical (Floresta Nacional do Tapajós), assim como, determinar a emissão de metano na interface solo-atmosfera durante o período chuvoso e de estiagem para o ano de 2012. Amostras de ar foram coletadas in situ diretamente do solo através do uso de câmaras estáticas e no perfil vertical da floresta em três alturas diferentes (2 m, 16 m e 36 m) e acima da copa (63 m) através do uso da torre micrometeorológica de 65 m. Posteriormente, as amostras de ar foram analisadas por cromatografia gasosa. A concentração de metano na estratificação vertical da vegetação foi de 1,866 ± 0,038 ppm e o fluxo foi ~ 15,50 mg de CH4.m-2 d-1 e a emissão de metano no solo foi 0,45 ± 0,71 mg de CH4 m-2 d-1. Portanto, no período de estudo o ecossistema florestal de terra-firme atuou como fonte de CH4 para atmosfera. Abstract Methane is the second most powerful greenhouse gas and its concentration in the atmosphere has increased 259% since 1750. The overall average of the molar fraction of CH4 reached a new record of 1813 ± 2 ppb in 2011. This study aims to quantify the concentration and flux of methane in the vertical profile of a tropical primary forest (Tapajós National Forest), as well as to determine the emission of methane in the air-soil interface during the rainy season and the dry season for the year 2012. Air samples were collected at the air-soil, interface using static chambers and throughout the vertical profile of the forest at three different heights (2 m, 16 m, and 36 m) and at above the canopy (63 m) accessed by a 65 m micrometeorological tower. Subsequently, the air samples were analyzed by gas chromatography. The concentration of methane in the vertical stratification of the vegetation was 1.866 ± 0,038 ppm and the flux was ~ 15.50 mg de CH4.m-2 d-1 and the emission of methane the soil was 0.45 ± 0,71 mg CH4.m-2 d-1. Therefore, for the period of study, the ecosystem of upland forest acted as a source of CH4 to the atmosphere.

International audience; The Dutch government has set an objective to reduce greenhouse gasses (GHG) emissions to 116 Mton CO2-equivalent in 2030. The agriculture sector aims for 11–23 Mton of GHG emission by 2050 and thus contributes to this objective. For this sector, the major contributor to the GHG emission in the Netherlands is the dairy sector. Before any mitigation strategies can be enrolled, some key facts need to be measured regarding the GHG emission on a farm. One of these key facts is the establishment of the baseline of GHG emission on a farm (and per cow). For this, we previously have built an infrastructure to measure and collect methane and carbon dioxide (near) real-time on a farm. The next challenges, addressed in the current study, were to (1) combine the private methane data, collected real-time through the infrastructure, with open source weather information, and (2) visualize both data streams for farmers, by developing an application that can be viewed on a web or mobile phone platform.

Water hyacinth is able to sequester large amounts of carbon dioxide (CO2) in wetlands. At the same time, the high production of organic matter combined with the plant’s capacity to limit the diffusion of oxygen from the atmosphere into the water creates favorable conditions for the production of methane (CH4). The combination of these mechanisms challenges the prediction of water hyacinth’s net effects on greenhouse gas (GHG) emissions. To unravel the impact of water hyacinth on GHG fluxes, we performed an extensive fieldwork study encompassing 22 sites dominated by water hyacinth in the Pantanal and Amazon during two different seasons. The highest CH4 emissions from water hyacinth beds occurred in shallow systems where sediment rooting enabled plant-mediated CH4 transport (307 ± 407 mg CH4 m−2 day−1 in waters shallower than 1 m, as opposed to 6.1 ± 10.6 mg CH4 m−2 day−1 in deeper waters). When CO2 uptake rates are added to the GHG budget (in terms of global warming potential), the water bodies were usually a GHG sink (− 5.2 ± 10 gCO2 eq m−2 day−1). The strength of the sink is highest in deeper systems where even a low water hyacinth coverage may already offset open water emissions. This dual effect of strong CO2 uptake—and at least temporal carbon storage in biomass—in combination with a high CO2–to-biomass-to-CH4 (and possibly back to CO2) conversion highlights the necessity to include vegetation characteristics in relation to depth when estimating GHG fluxes for tropical wetlands.

The paper presents the variability of methane emissions in mining excavations in the Brzeszcze mine (Poland) against the background of hard coal output, geological and mining factors. The geological structure of the Upper Silesian Coal Basin (USCB) is very diverse. The Brzeszcze coal deposit is located close to the large and permeable Jawiszowice fault which increases the methane hazard during mining activities performed close to this fault. The overall decrease in hard coal output (1988–2018) has coincided with a rapid increase in methane emissions (1997–2018). Throughout the study period, hard coal output decreased threefold from 3.9 to 1.2 million Mg annually. Coal extraction in high methane content beds (e.g. 510, 405/1, 364, 352) increases the total methane (CH4) emission into mining excavations, aggravating the methane hazard due to the high explosiveness of the gas. To protect miners, coal workings need to be continuously ventilated, taking the harmful gas out of the mine (ventilation air methane emission) or methane needs to be captured by underground methane systems (degassing). Every year, over 34 million m3 of CH4 is captured by the drainage systems and over 70 million m3 CH4 (average) is discharged through ventilation shafts into the atmosphere. The presence of the large, permeable regional dislocation, the Jawiszowice fault zone, shaped the methane concentration in the fault vicinity, when the highest methane emissions during coal mining was studied.

The objective of this experiment was to study the effects of incorporating lemon leaves and rice straw into the compound feed of diets for dairy goats. Ten Murciano-Granadina dairy goats (n = 5 per group) in mid-lactation were used in a crossover design experiment (2 treatments across 2 periods). Goats were fed a mixed ration with barley grain (control, CON) or CON plus lemon leaves [189 g/kg of dry matter (DM)] and rice straw (120 g/kg of DM) in place of barley grain (LRS). Soybean oil (19 g/kg of DM) was added to the LRS diet to make it isoenergetic (17 MJ of gross energy/kg of DM) relative to CON. After 14 d on their respective treatments, goats were allocated to individual metabolism cages for another 7 d. Subsequently, feed intake, total fecal and urine output, and milk yield were recorded daily over the first 5 d. During the last 2 d, ruminal fluid and blood samples were collected, along with individual gas exchange measurements recorded by a mobile open-circuit indirect calorimetry system using a head box. No differences in DM intake were detected, and ME intake in LRS was lower than in CON (1,095 vs. 1,180 kJ/kg of metabolic body weight). No differences were observed in milk production, but milk fat content was greater in LRS (6.4%) than in CON (5.6%). Greater concentrations of monounsaturated (14.94 vs. 11.96 g/100 g of milk fat) and polyunsaturated fatty acids (4.53 vs. 4.03 g/100 g of milk fat) were detected in the milk of goats fed LRS compared with CON. Atherogenicity (2.68 vs.1.91) and thrombogenic (4.58 vs. 2.81) indices were lower with LRS compared with CON. Enteric CH4 emission was lower in LRS (24.3 g/d) compared with CON (31.1 g/d), probably due to the greater lipid content and unsaturated fatty acid profile of lemon leaves and the soybean oil added in the LRS diet. Overall, data suggest that incorporating lemon leaves and rice straw into lactating goat diets is effective in reducing CH4 emissions while allowing improvements in milk fat production and milk thrombogenic index without affecting production performance. Thus, their inclusion in compound feeds fed to small ruminants appears warranted and would have multiple positive effects, as on efficiency of nutrient use, human health, and the environment.

This research was carried out in farms which have 100 and more cows with commercial biogas production capacity, in 2019 in Tekirdag. This is because it is stated that if the livestock enterprises have at least 100 animals, biogas production can be realized economically. The distribution and number of farms with this feature in districts were provided from Tekirdag Food, Agriculture and Livestock Provincial Directorate. Biogas is generally used by converting it to heat and electrical energy. While it is used mostly for heating purposes in small farms, electricity and heat energy are provided in CHP units in large farms. Total methane production potential and energy value were calculated as 22 466 Nm3day-1 and 81 756.4 MWhyear-1, respectively. The highest methane production potential and energy value is in Muratli district and the least is in Çerkezkoÿ district. It was determined that 42 512.48 MWhyear-1 useful heat energy and in CHP unit 28 614.17 MWhyear-1 electricity energy and 19 784.65 MWhyear-1additional heat energy could be obtained from methane produced by anaerobic fermentation. It is determined that 19 067.56 tons CO2eyear-1 of methane will be released if the manure is stored outdoors. It was determined that methane emission could be reduced by 1 087.13 tons CO2eyear-1 if the nitrogen was used in fermentation residues instead of the chemical fertilizer. Total methane retention in the use of methane for heat purposes will be 31 590.55 tons CO2eyear-1. Methane emissions will be reduced by 12 522.99 tons CO2eyear-1 when used for heat purposes, than the conditions in which the manure is stored outdoors. When methane is used in the CHP unit to provide electricity and heat energy, total methane retention is calculated as 38 467.6 tons CO2eyear-1, and the decrease in methane emission is calculated as 19 400 tons CO2eyear-1. In animal husbandry enterprises that are located in Tekirdag and are commercially producing, evaluation of manure without long-term storage by means of anaerobic digestion is important in terms of meeting of the energy requirement and reducing methane emission and the government should encourage enterprises in this regard. © 2020 Namik Kemal University - Agricultural Faculty. All rights reserved.

Water drainage is an important mitigation option for reducing CH4 (methane) emissions from residue-amended paddy soils. Several studies have indicated a long-term reduction in CH4 emissions, even after re-flooding, suggesting that the mechanism goes beyond creating temporary oxidized conditions in the soil. In this pot trial, the effects of different drainage patterns on straw-derived CH4 and CO2 (carbon dioxide) emissions were compared to identify the balance between straw-carbon CH4 and CO2 emissions influenced by soil aeration over different periods, including effects of drainage on emissions during re-flooding. The water treatments included were: continuous flooding [C] as the control and five drainage patterns (pre-planting drainage [P], early-season drainage [E], midseason drainage [M], pre-planting plus midseason drainage [PM], early-season-plus-midseason drainage [EM]). An equal amount of 13C-enriched rice straw was applied to all treatments to identify straw-derived 13C-gas emissions from soil carbon derived emissions. The highest fluxes of CH4 and δ13C-CH4 were recorded from the control treatment in the first week after straw application. The CH4 flux and δ13C-CH4 were reduced the most (0.1–0.8 μg CH4 g−1 soil day−1 and -13 to −34‰) in the pre-planting and pre-planting plus midseason drainage treatments at day one after transplanting. Total and straw-derived CH4 emissions were reduced by 69% and 78% in pre-planting drainage and 77% and 87% in pre-planting plus midseason drainage respectively, compared to control. The early-season, midseason, pre-planting plus midseason and early-season-plus-midseason drainage treatments resulted in higher total and straw-derived CO2 emissions compared to the control and pre-planting drainage treatments. The pre-planting and pre-planting plus midseason drainage treatments lowered the global warming potential by 47–53%, and early-season and early-season-plus-midseason drainage treatments reduced it by 24–31% compared to control. By using labelled crop residues, this experiment demonstrates a direct link between early drainage and reduced CH4 emissions from incorporated crop residues, eventually leading to a reduction in total global warming potential. It is suggested that accelerated decomposition of the residues during early season drainage prolonged the reduction in CH4 emissions. Therefore, it is important to introduce the early drainage as an effective measure to mitigate CH4 emissions from crop residues.

This study evaluated methane (CH 4) emission, intake, digestibility, and nitrogen efficiency in sheep fed diets containing replacement levels (0%, 33%, 50%, and 67% of soybean meal with euglena). In this experiment, four Corriedale wether sheep with an initial body weight of 53.8 ± 4.6 were arranged in a 4 × 4 Latin square design. This experiment lasted 84 days, divided into four experimental periods. Each period lasted 21 days, which consists of 14 days of adaptation to the diets, 5 days to collect samples, and 2 days to collect gas emission from sheep. Methane emission expressed as L/kg DM intake or g/kg DM intake reduced by up to 37% and the energy loss via CH 4 (% of GE intake) reduced by up to 34%. No differences (p > 0.05) were observed in DM and OM intake and whole tract apparent DM digestibility due to substitution of soybean meal with euglena. The total CP loss reduced significantly (linear, p

In this study, the total methane (CH4) generation rate and gas recovery efficiency at two Danish landfills were determined by field measurements. The landfills are located close to each other and are connected to the same gas collection system. The tracer gas dispersion method was used for quantification of CH4 emissions from the landfills, while the CH4 oxidation efficiency in the landfill cover layers was determined by stable carbon isotopic technique. The total CH4 generation rate was estimated by a first-order decay model (Afvalzorg) and was compared with the total CH4 generation rate determined by field measurements. CH4 emissions from the two landfills combined ranged from 29.1 to 49.6 kg CH4/h. The CH4 oxidation efficiency was 6–37%, with an average of 18% corresponding to an average CH4 oxidation rate of 8.1 kg CH4/h. The calculated gas recovery efficiency was 59–76%, indicating a high potential for optimization of the gas collection system. Higher gas recovery efficiencies (73–76%) were observed after the commencement of gas extraction from a new section of one of the landfills. A good agreement was observed between the average total CH4 generation rates determined by field measurements (147 kg CH4/h) and those estimated by the Afvalzorg model (154 kg CH4/h).

International environmental agreements have led to the need to reduce methane emission by dairy cows. Reduction could be achieved through selective breeding. The aim of this study was to quantify the genetic variation of methane emission by Dutch Holstein Friesian cows measured using infrared sensors installed in automatic milking systems (AMS). Measurements of CH 4 and CO 2 on 1,508 Dutch Holstein Friesian cows located on 11 commercial dairy farms were available. Phenotypes per AMS visit were the mean of CH 4 , mean of CO 2 , mean of CH 4 divided by mean of CO 2 , and their log 10 -transformations. The repeatabilities of the log 10 -transformated methane phenotypes were 0.27 for CH 4 , 0.31 for CO 2 , and 0.14 for the ratio. The log 10 -transformated heritabilities of these phenotypes were 0.11 for CH 4 , 0.12 for CO 2 , and 0.03 for the ratio. These results indicate that measurements taken using infrared sensors in AMS are repeatable and heritable and, thus, could be used for selection for lower CH 4 emission. Furthermore, it is important to account for farm, AMS, day of measurement, time of day, and lactation stage when estimating genetic parameters for methane phenotypes. Selection based on log 10 -transformated CH 4 instead of the ratio would be expected to give a greater reduction of CH 4 emission by dairy cows.

To measure methane (CH4) emissions from cattle on-farm, a number of methods have been developed. Combining measurements made with different methods in one data set could lead to an increased power of further analyses. Before combining the measurements, their agreement must be evaluated. We analysed data obtained with a handheld laser methane detector (LMD) and the GreenFeed system (GF), as well as data obtained with LMD and Fourier Transformed Infrared (FTIR) and Non-dispersive Infrared (NDIR) breath analysers (sniffers) installed in the feed bin of automatic milking systems. These devices record short-term breath CH4 concentrations from cows and make it possible to estimate daily CH4 production in g/d which is used for national CH4 emission inventories and genetic studies. The CH4 is released by cows during eructation and breathing events, resulting in peaks of CH4 concentrations during a measurement which represent the respiratory cycle. For LMD, the average CH4 concentration of all peaks during the measurement (P_MEAN in ppm × meter) was compared with the average daily CH4 production (g/d) measured by GF on 11 cows. The comparison showed a low concordance correlation coefficient (CCC; 0.02) and coefficient of individual agreement (CIA; 0.06) between the methods. The repeated measures correlation (rp) of LMD and GF, which can be seen as a proxy for the genetic correlation, was, however, relatively strong (0.66). Next, based on GF, a prediction equation for estimating CH4 in g/d (LMD_cal) using LMD measurements was developed. LMD_cal showed an improved agreement with GF (CCC = 0.22, CIA = 0.99, rp = 0.74). This prediction equation was used to compare repeated LMD measurements (LMD_val in g/d) with CH4 (g/d) measured with FTIR (n = 34 cows; Data Set A) or NDIR (n = 39 cows; Data Set B) sniffer. A low CCC (A: 0.28; B: 0.17), high CIA (A: 0.91; B: 0.87) and strong rp (A: 0.57; B: 0.60) indicated that there was some agreement and a minimal re-ranking of the cows between sniffer and LMD. Possible sources of disagreement were cow activity (LMD: standing idle; sniffer: eating and being milked) and the larger influence of wind speed on LMD measurement. The LMD measurement was less repeatable (0.14–0.27) than the other techniques studied (0.47–0.77). Nevertheless, GF, LMD and the sniffers ranked the cows similarly. The LMD, due to its portability and flexibility, could be used to study CH4 emissions on herd or group level, as a validation tool, or to strengthen estimates of genetic relationships between small-scale research populations.

Methane is a greenhouse gas which poses a great threat to life on earth as its emissions directly contribute to global warming and methane has a 28-fold higher warming potential over that of carbon dioxide. Ruminants have been identified as a major source of methane emission as a result of methanogenesis by their respective gut microbiomes. Various plants produce highly bioactive compounds which can be investigated to find a potential inhibitor of methyl-coenzyme M reductase (the target protein for methanogenesis). To speed up the process and to limit the use of laboratory resources, the present study uses an in-silico molecular docking approach to explore the anti-methanogenic properties of phytochemicals from Cymbopogon&nbsp, citratus, Origanum vulgare, Lavandula officinalis, Cinnamomum zeylanicum, Piper betle, Cuminum cyminum, Ocimum gratissimum, Salvia sclarea, Allium sativum, Rosmarinus officinalis and Thymus vulgaris. A total of 168 compounds from 11 plants were virtually screened. Finally, 25 scrutinized compounds were evaluated against methyl-coenzyme M reductase (MCR) protein using the AutoDock 4.0 program. In conclusion, the study identified 21 out of 25 compounds against inhibition of the MCR protein. Particularly, five compounds: rosmarinic acid (−10.71 kcal/mol), biotin (−9.38 kcal/mol), α-cadinol (−8.16 kcal/mol), (3R,3aS,6R,6aR)-3-(2H-1,3-benzodioxol-4-yl)-6-(2H-1,3-benzodioxol-5-yl)-hexahydrofuro[3,4-c]furan-1-one (−12.21 kcal/mol), and 2,4,7,9-tetramethyl-5decyn4,7diol (−9.02 kcal/mol) showed higher binding energy towards the MCR protein. In turn, these compounds have potential utility as rumen methanogenic inhibitors in the proposed methane inhibitor program. Ultimately, molecular dynamics simulations of rosmarinic acid and (3R,3aS,6R,6aR) -3-(2H-1,3-benzodioxol-4-yl)-6-(2H-1,3-benzodioxol-5-yl)-hexahydrofuro[3,4-c]furan-1-one yielded the best possible interaction and stability with the active site of 5A8K protein for 20 ns.

Animal manure is a significant source of ammonia, methane, hydrogen sulfide, and odor emissions. Manure acidification to pH 5.5 using sulfuric acid (H 2SO 4) is an approved method for reducing ammonia and methane emissions from barns and retaining bioavailable nitrogen in the slurry for subsequent field fertilization. However, the use of H 2SO 4 may increase the emission of malodorous sulfur compounds and reduces subsequent biogas production. In this study, we investigated if substituting a part of the H 2SO 4 treatment with acetic acid (CH 3COOH) improves manure emissions. In two experiments, cattle manure was incubated for 11 days each and acidified daily with either i) H 2SO 4 (4M) or CH 3COOH (4M), or ii) mixes of both acids (4M H 2SO 4 + 8M CH 3COOH, in volume ratios of 75:25, 50:50, and 25:75) until pH 5.5. The emission of ammonia, methane, hydrogen sulfide, and volatile organic compounds (VOCs) was monitored continuously. At the end of both experiments, cumulative ammonia emission was reduced by 75% by H 2SO 4 and by 83% by CH 3COOH, indicating that CH 3COOH was more efficient. Acetic acid almost completely eliminated CH 4 emission, while H 2SO 4 reduced CH 4 emission by 89%. Furthermore, CH 3COOH acidification resulted in lower odorant emissions compared to H 2SO 4. Based on the second experiment, we recommend using a high percentage of CH 3COOH during the first days of acidification, followed by a mix containing at least 50% CH 3COOH, to achieve a high mitigation efficiency with a lower emission of sulfur compounds compared to H 2SO 4 alone.

Although the effect of animal and diet factors on enteric methane (CH4) emissions from confined cattle has been extensively examined, less data is available regarding CH4 emissions from grazing young cattle. A study was undertaken to evaluate the effect of the physiological state of Holstein-Friesian heifers on their enteric CH4 emissions while grazing a perennial ryegrass sward. Two experiments were conducted: Experiment 1 ran from May 2011 for 11 weeks and Experiment 2 ran from August 2011 for 10 weeks. In each experiment, Holstein-Friesian heifers were divided into three treatment groups (12 animals/group) consisting of calves, yearling heifers, and in-calf heifers (average ages: 8.5, 14.5, and 20.5 months, respectively). Methane emissions were estimated for each animal in the final week of each experiment using the sulfur hexafluoride tracer technique. Dry matter (DM) intake was estimated using the calculated metabolizable energy (ME) requirement divided by the ME concentration in the grazed grass. As expected, live weight increased with increasing animal age (P < 0.001); however, there was no difference in live weight gain among the three groups in Experiment 1, although in Experiment 2, this variable decreased with increasing animal age (P < 0.001). In Experiment 1, yearling heifers had the highest CH4 emissions (g·d−1) and in-calf heifers produced more than calves (P < 0.001). When expressed as CH4 emissions per unit of live weight, DM intake, and gross energy (GE) intake, yearling heifers had higher emission rates than calves and in-calf heifers (P < 0.001). However, the effects on CH4 emissions were different in Experiment 2, in which CH4 emissions (g·d−1) increased linearly with increasing animal age (P < 0.001), although the difference between yearling and in-calf heifers was not significant. The CH4/live weight ratio was lower in in-calf heifers than in the other two groups (P < 0.001), while CH4 energy output as a proportion of GE intake was lower in calves than in yearling and in-calf heifers (P < 0.05). All data were then pooled and used to develop prediction equations for CH4 emissions. All relationships are significant (P < 0.001), with R2 values ranging from 0.630 to 0.682. These models indicate that CH4 emissions could be increased by 0.252 g·d−1 with an increase of 1 kg live weight or by 14.9 g·d−1 with an increase of 1 kg·d−1 of DM intake; or, the CH4 energy output could be increased by 0.046 MJ·d−1 with an increase of 1 MJ·d−1 of GE intake. These results provide an alternative approach for estimating CH4 emissions from grazing dairy heifers when actual CH4 emission data are not available.

OBJECTIVE The study examined the effect of condensed tannins (CT) containing Ficus infectoria and Psidium guajava leaf meal mixture (LMM) supplementation on nutrient metabolism, methane emission and performance of lambs. METHODS Twenty four lambs of ~6 months age (average body weight 10.1±0.60 kg) were randomly divided into 4 dietary treatments (CT-0, CT-1, CT-1.5, and CT-2 containing 0, 1.0, 1.5, and 2.0 percent CT through LMM, respectively) consisting of 6 lambs each in a completely randomized design. All the lambs were offered a basal diet of wheat straw ad libitum, oat hay (100 g/d) along with required amount of concentrate mixture to meet their nutrient requirements for a period of 6 months. After 3 months of experimental feeding, a metabolism trial of 6 days duration was conducted on all 24 lambs to determine nutrient digestibility and nitrogen balance. Urinary excretion of purine derivatives and microbial protein synthesis were determined using high performance liquid chromatography. Respiration chamber study was started at the mid of 5th month of experimental feeding trial. Whole energy balance trials were conducted on individual lamb one after the other, in an open circuit respiration calorimeter. RESULTS Intake of dry matter and organic matter (g/d) was significantly (p

The effects of adding essential oils (EO) on rumen fermentation and methane production were examined. The aim of experiment one was to screen the effects of four different EO (clove oil (CLO), white thyme oil (WTO), citronella oil (CTO) and anise oil (ANO)) at 500 mg/L of culture fluid on methane production under in vitro conditions. Rumen contents collected from a cannulated Holstein dairy cow was used in a 24-hour batch culture experiment. Treatments were a control (CON) or CON plus EO at 500 mg/L. Results showed that all EOs, except CTO, decreased (p ≤ .05) methane production. The aim of experiment two was to test the effects of three different dose levels of CLO, WTO, and ANO on methane production and fermentation in 24-h batch culture experiments. Treatments were CON or CON plus EO supplemented at 125, 250, and 500 mg/L. Relative to CON, methane production decreased (p ≤ .05) with the three EO at the 500 mg/L dose. At the 250 mg/L dose, ANO and CLO decreased (p ≤ .05) methane production and at the 125 mg/L dose, only CLO decreased methane production. Relative to CON, total VFA concentration declined (p ≤.05) in cultures incubated with WTO and with ANO at 500 mg/L dose. Relative to CON, the addition of CLO, WTO and ANO at 500 mg/L decreased (p ≤ .05) dry matter (DM) digestibility. In conclusion, our results showed that EO effects on methane production depend on EO source and dose level. Although the addition of ANO and WTO at the high doses resulted in lower methane production, they had negatively impacted on rumen microbial fermentation. Clove oil on the other hand reduced methane production without negatively impacting rumen fermentation.

Tannins have become important phytochemicals in ruminant production, due to their wide range of biological activities. The use of a crude extract often comes with limitations, such as reduced feed intake and fibre digestibility, which could be overcome by the use of encapsulated tannin extract. In this study, four rumen-cannulated Merino wethers were used in a 4 &times, 4 Latin square design to determine the effect of encapsulating Acacia mearnsii tannin extract on intake, nutrient digestibility, and methane emission. The animals were placed on one of the following diets: control diet only, diet + silvafeed (Silvafeed ByPro, 10 g/kg feed), diet + Acacia tannin extract (ATE), 40 g/kg feed), and, diet + lipid-encapsulated-ATE (palm oil encapsulated ATE, 50 g/kg feed) in 4 cycles. Wethers were offered an Eragrotis and Lucerne hay-based total mixed ration diet above maintenance requirement with forage: concentrate ratio 50:50. Silvafeed, a commercial tannin additive, was used as a positive control. Nutrient intake was not different across the treatments, but nutrient digestibility was affected by dietary additives (p &lt, 0.05). Compared to the control, and unlike the crude extract, encapsulated-ATE and silvafeed did not reduce dry matter, organic matter, and neutral detergent fibre digestibility. While the overall N-retention and total N-excretion (g/d) were not affected by dietary additives, ATE and encapsulated-ATE diets reduced urine-N excretion (g/d) and only a slight reduction was observed in silvafeed diet. The faecal-N proportion was highest in the ATE diet (388 g/kg N-intake), followed by encapsulated-ATE (317 g/kg), and silvafeed (267 g/kg), with the control diet having the lowest proportion (230 g/kg). The acetate:propionate (A:P) ratio reduced as a result of the inclusion of dietary additives with crude ATE and silvafeed having lower A:P ratio compared to the control diet. Methane production expressed in g/kg dry matter (DM) intake was reduced by 12%, 30% and 19% in the silvafeed, crude ATE and encapsulated-ATE diets, respectively (p &lt, 0.05). The reduced methane production with higher neutral detergent fibre (NDF) digestibility in the encapsulated-ATE, compared to the crude-ATE, confirms that encapsulated-tannin can be used as an additive in ruminant diets.

To date, estimation of greenhouse gas (GHG) emissions from the natural gas (NG) value chain have focused on upstream (production) and midstream (gathering, transmission, and storage) operations. In this study, we estimate methane emissions from an important downstream consumer of NG, the ammonia fertilizer industry, which commonly uses NG as a feedstock and a fuel for the production of ammonia and other upgraded products. Using a Google Street View (GSV) car equipped with a high-precision methane analyzer, we adopted a mobile sensing approach to measure methane mixing ratios along public roads that are downwind of the ammonia fertilizer plants. Useful data were collected from six plants, which represent >25% of the total number of U.S NG-based ammonia fertilizer plants, and use >20% of the total NG consumption by this industry. Based on the measured data, a source characterization model was applied to estimate the methane emission rates from the upwind plants. Assuming that the estimates are representative of emissions during normal operations of a plant, we calculated the NG loss rate (i.e. the ratio between NG emission rate and NG throughput). If the sampled plants are representative of the U.S. ammonia fertilizer industry, the industrial-averaged NG loss rate (± standard deviation) is estimated to be 0.34% (±0.20%), and the total methane emissions (± standard deviation) from this industry are estimated to be 29 (±18) Gigagram per year (Gg CH4/yr) in 2015–2016. This is significantly higher than the reported methane emissions of 0.2 Gg CH4/yr from the U.S. EPA’s Facility Level Information on Greenhouse Gas Tools (FLIGHT). This study begins to fill an important knowledge gap in quantifying methane emissions along the NG value chain, and demonstrates the capability of mobile sensing for characterizing airborne emissions.

This work aims to investigate the methane emissions from integrated vertical-flow constructed wetlands (IVCWs) when ethanol is added as an external carbon source. In this study, a gradient of ethanol (0, 2, 4, 8, 16 and 32 mmol/L) was added as the carbon source in an IVCW planted with Cyperus alternifolius L. The results showed that the methane emission flux at an ethanol concentration of 32 mmol/L was 32.34 g CH4 m&minus, 2 day&minus, 1 less than that of the control experiment (0 mmol/L) and that the methane emission flux at an ethanol concentration of 16 mmol/L was 5.53 g CH4 m&minus, 1 less than that at 0 mmol/L. In addition, variations in the water quality driven by the different ethanol concentrations were found, with a redox potential range of &minus, 64 mV to +30 mV, a pH range of 6.6&ndash, 6.9, a chemical oxygen demand (COD) removal rate range of 41% to 78%, and an ammonia nitrogen removal rate range of 59% to 82% after the ethanol addition. With the average CH4-C/TOC (%) value of 35% driven by ethanol, it will be beneficial to understand that CH4-C/TOC can be considered an ecological indicator of anthropogenic methanogenesis from treatment wetlands when driven by carbon sources or carbon loading. It can be concluded that adding ethanol as an external carbon source can not only meet the water quality demand of the IVCW treatment system but also stimulate and increase the average CH4 emissions from IVCWs by 23% compared with the control experiment. This finding indicates that an external carbon source can stimulate more CH4 emissions from IVCWs and shows the importance of carbon sources during sewage treatment processes when considering greenhouse emissions from treated wetlands.

Destabilization of intrapermafrost gas hydrate is one possible reason for methane emission on the Arctic shelf. The formation of these intrapermafrost gas hydrates could occur almost simultaneously with the permafrost sediments due to the occurrence of a hydrate stability zone after sea regression and the subsequent deep cooling and freezing of sediments. The top of the gas hydrate stability zone could exist not only at depths of 200&ndash, 250 m, but also higher due to local pressure increase in gas-saturated horizons during freezing. Formed at a shallow depth, intrapermafrost gas hydrates could later be preserved and transform into a metastable (relict) state. Under the conditions of submarine permafrost degradation, exactly relict hydrates located above the modern gas hydrate stability zone will, first of all, be involved in the decomposition process caused by negative temperature rising, permafrost thawing, and sediment salinity increasing. That&rsquo, s why special experiments were conducted on the interaction of frozen sandy sediments containing relict methane hydrates with salt solutions of different concentrations at negative temperatures to assess the conditions of intrapermafrost gas hydrates dissociation. Experiments showed that the migration of salts into frozen hydrate-containing sediments activates the decomposition of pore gas hydrates and increase the methane emission. These results allowed for an understanding of the mechanism of massive methane release from bottom sediments of the East Siberian Arctic shelf.

Permafrost soils and arctic wetlands methane emissions represent an important challenge for modeling the future climate. Here we present a process-based model designed to correctly represent the main thermal, hydrological, and biogeochemical processes related to these emissions for general land surface modeling. We propose a new multilayer soil carbon and gas module within the Interaction Soil-Biosphere-Atmosphere (ISBA) land-surface model (LSM). This module represents carbon pools, vertical carbon dynamics, and both oxic and anoxic organic matter decomposition. It also represents the soil gas processes for CH4, CO2, and O2 through the soil column. We base CH4 production and oxydation on an O2 control instead of the classical water table level strata approach used in state-of-the-art soil CH4 models. We propose a new parametrization of CH4 oxydation using recent field experiments and use an explicit O2 limitation for soil carbon decomposition. Soil gas transport is computed explicitly, using a revisited formulation of plant-mediated transport, a new representation of gas bulk diffusivity in porous media closer to experimental observations, and an innovative advection term for ebullition. We evaluate this advanced model on three climatically distinct sites : two in Greenland (Nuuk and Zackenberg) and one in Siberia (Chokurdakh). The model realistically reproduces methane and carbon dioxide emissions from both permafrosted and nonpermafrosted sites. The evolution and vertical characteristics of the underground processes leading to these fluxes are consistent with current knowledge. Results also show that physics is the main driver of methane fluxes, and the main source of variability appears to be the water table depth.