CH4 Emission Rates Research Articles

Potential option for mitigating methane emission from tropical paddy rice through selection of suitable rice varieties

Cultivation of rice, a globally important cereal crop, is a major cause of emission of the greenhouse gas (GHG) methane (CH4), giving rise to global warming. Physiological and anatomical characteristics of rice plants associated with CH4 emission were studied in six high-yielding rice varieties, Dikhow, Dishang, Jaya, Kolong, Kopilee and Lachit, during the pre-monsoon season (April–August) for 2 years (2013 and 2014) in a tropical climate in India. Significant differences (P < 0.001) in photosynthetic rate among the rice varieties were recorded and were found to influence CH4 emission from the ecosystem. Rate of CH4 emission was found correlated (r = 0.942) with size of the xylem vessels of the node of the varieties. Kolong, Lachit and Dikhow were identified as low CH4 emitters with smaller xylem vessels. The recorded GHG intensity (GHGI) revealed rice varieties as a source of GHGs, and among the varieties, Kopilee as a major source of CH4, with GHGI of 0.083 and 0.093 during 2013 and 2014, respectively. Results suggest that selection of suitable rice varieties with high grain yield accompanied by lower rate of CH4 emission can be a viable option for reduction of CH4 emissions from rice agriculture.

The Indianapolis Flux Experiment (INFLUX): A test-bed for developing urban greenhouse gas emission measurements.

The objective of the Indianapolis Flux Experiment (INFLUX) is to develop, evaluate and improve methods for measuring greenhouse gas (GHG) emissions from cities. INFLUX’s scientific objectives are to quantify CO2 and CH4 emission rates at 1 km resolution with a 10% or better accuracy and precision, to determine whole-city emissions with similar skill, and to achieve high (weekly or finer) temporal resolution at both spatial resolutions. The experiment employs atmospheric GHG measurements from both towers and aircraft, atmospheric transport observations and models, and activity-based inventory products to quantify urban GHG emissions. Multiple, independent methods for estimating urban emissions are a central facet of our experimental design. INFLUX was initiated in 2010 and measurements and analyses are ongoing. To date we have quantified urban atmospheric GHG enhancements using aircraft and towers with measurements collected over multiple years, and have estimated whole-city CO2 and CH4 emissions using aircraft and tower GHG measurements, and inventory methods. Significant differences exist across methods; these differences have not yet been resolved; research to reduce uncertainties and reconcile these differences is underway. Sectorally- and spatially-resolved flux estimates, and detection of changes of fluxes over time, are also active research topics. Major challenges include developing methods for distinguishing anthropogenic from biogenic CO2 fluxes, improving our ability to interpret atmospheric GHG measurements close to urban GHG sources and across a broader range of atmospheric stability conditions, and quantifying uncertainties in inventory data products. INFLUX data and tools are intended to serve as an open resource and test bed for future investigations. Well-documented, public archival of data and methods is under development in support of this objective.

Minor methane emissions from an Alpine hydropower reservoir based on monitoring of diel and seasonal variability.

We monitored CH4 emissions during the ice-free period of an Alpine hydropower reservoir in the Swiss Alps, Lake Klöntal, to investigate mechanisms responsible for CH4 variability and to estimate overall emissions to the atmosphere. A floating eddy-covariance platform yielded total CH4 and CO2 emission rates at high temporal resolution, while hydroacoustic surveys provided no indication of CH4 ebullition. Higher CH4 fluxes (2.9 ± 0.1 mg CH4 per m2 per day) occurred during the day when surface water temperatures were warmer and wind speeds higher than at night. Piston velocity estimates (k600) showed an upper limit at high wind speeds that may be more generally valid also for other lakes and reservoirs with limited CH4 dissolved in the water body: above 2.0 m s-1 a further increase in wind speed did not lead to higher CH4 fluxes, because under such conditions it is not the turbulent mixing and transport that limits effluxes, but the resupply of CH4 to the lake surface. Increasing CH4 fluxes during the warm season showed a clear spatial gradient once the reservoir started to fill up and flood additional surface area. The warm period contributed 27% of the total CH4 emissions (2.6 t CH4 per year) estimated for the full year and CH4 accounted for 63% of carbonic greenhouse gas emissions. Overall, the average CH4 emissions (1.7 to 2.2 mg CH4 per m2 per day determined independently from surface water samplings and eddy covariance, respectively) were small compared to most tropical and some temperate reservoirs. The resulting greenhouse gas (GHG) emissions in CO2-equivalents revealed that electricity produced in the Lake Klöntal power plant was relatively climate-friendly with a low GHG-to-power output ratio of 1.24 kg CO2,eq per MW h compared to 6.5 and 8.1 kg CO2,eq per MW h associated with the operation of solar photovoltaics and wind energy, respectively, or about 980 kg CO2,eq per MW h for coal-fired power plants.

Assessing the optimized precision of the aircraft mass balance method for measurement of urban greenhouse gas emission rates through averaging

To effectively address climate change, aggressive mitigation policies need to be implemented to reduce greenhouse gas emissions. Anthropogenic carbon emissions are mostly generated from urban environments, where human activities are spatially concentrated. Improvements in uncertainty determinations and precision of measurement techniques are critical to permit accurate and precise tracking of emissions changes relative to the reduction targets. As part of the INFLUX project, we quantified carbon dioxide (CO2), carbon monoxide (CO) and methane (CH4) emission rates for the city of Indianapolis by averaging results from nine aircraft-based mass balance experiments performed in November-December 2014. Our goal was to assess the achievable precision of the aircraft-based mass balance method through averaging, assuming constant CO2, CH4 and CO emissions during a three-week field campaign in late fall. The averaging method leads to an emission rate of 14,600 mol/s for CO2, assumed to be largely fossil-derived for this period of the year, and 108 mol/s for CO. The relative standard error of the mean is 17% and 16%, for CO2 and CO, respectively, at the 95% confidence level (CL), i.e. a more than 2-fold improvement from the previous estimate of ~40% for single-flight measurements for Indianapolis. For CH4, the averaged emission rate is 67 mol/s, while the standard error of the mean at 95% CL is large, i.e. ±60%. Given the results for CO2 and CO for the same flight data, we conclude that this much larger scatter in the observed CH4 emission rate is most likely due to variability of CH4 emissions, suggesting that the assumption of constant daily emissions is not correct for CH4 sources. This work shows that repeated measurements using aircraft-based mass balance methods can yield sufficient precision of the mean to inform emissions reduction efforts by detecting changes over time in urban emissions.

Interactive effects of temperature and UVB radiation on methane emissions from different organs of pea plants grown in hydroponic system

There is no information on variation of methane (CH4) emissions from plant organs exposed to multiple environmental factors. We investigated the interactive effects of temperature and ultraviolet-B (UVB) radiation on CH4 emissions from different organs of pea (Pisum sativum L. var. UT234 Lincoln). Plants were grown hydroponically under two temperatures (22/18°C and 28/24°C; 16h day/8h night) and two levels of UVB radiation [0 and 5kJm−2 d−1] in controlled-environment growth chambers for ten days, after two weeks of initial growth under ambient temperatures. Methane emission, dry mass, growth index, electrical conductivity (EC), pectin, total chlorophyll content, gas exchange and flavonoids were measured in the appropriate plant organs – leaf, stem and root. Higher temperatures increased CH4 emissions, leaf mass ratio, and shoot: root mass ratio. Neither temperature nor UVB had significant effects on leaf, stem, root and total dry mass, EC, pectin, total chlorophyll, as well as specific leaf mass. Among plant organs, there were differences in CH4, EC, pectin and total chlorophyll. Methane and EC were highest for the stem and lowest for the leaf; leaf had highest, but stem had lowest, pectin content; total chlorophyll was highest in the leaf but lowest in the root. Higher temperatures decreased leaf flavonoids, net carbon dioxide assimilation, and water use efficiency. Overall, environmental stressors increased aerobic CH4 emission rates, which varied with plant organs.

Effects of increased temperatures and rice straw incorporation on methane and nitrous oxide emissions in a greenhouse experiment with rice

We investigated the effect of increased temperatures of water and soil, together with the incorporation of rice straw, on emissions of methane (CH4) and nitrous oxide (N2O), and the daily variation in CH4 emissions. Three temperature treatments (floodwater temperature), ambient, ambient +2°C and ambient +4°C, and two amounts of rice straw (0 and 6 t ha−1) were arranged in a randomized complete block design with four replications. The emissions of CH4 and N2O and the soil's redox potential (Eh) were measured weekly for two crop cycles. Daily variation in CH4 emission rates was measured with and without rice straw incorporation in planted and unplanted soil (with no warming treatments) during four growth stages of the crop. Methane emissions increased by as much as 91% with increasing amounts of water and soil temperature (+2 and +4°C), up to 34–35°C. Increases in temperature (+2 and +4°C above ambient) above 34–35°C decreased emissions by 30–36%. A decrease in soil Eh to < −100 mV and in CH4 emissions was observed earlier in the pots containing rice straw than in those without straw. Methane emissions varied daily; they were larger from 11:00 to 14:00 hours, particularly in unplanted soil. They showed positive correlations with the temperatures of both soil and air. In contrast, N2O emissions were negligible throughout the growing season. The emissions of CH4 evidently depend on the background temperature range; in our experiment, CH4 emissions increased up to 34°C and then they decreased above that.Highlights:GHG emissions were measured from flooded rice soil under elevated temperatures. Temperature, straw incorporation and rice plants affected daily variation in methane emissions. An increase in temperature increased methane emission by up to 91%. Increased temperature decreased methane emissions when background temperature was above 34–35°C.

Modeling CH4 Emissions from Natural Wetlands on the Tibetan Plateau over the Past 60 Years: Influence of Climate Change and Wetland Loss

The natural wetlands of the Tibetan Plateau (TP) are considered to be an important natural source of methane (CH4) to the atmosphere. The long-term variation in CH4 associated with climate change and wetland loss is still largely unknown. From 1950 to 2010, CH4 emissions over the TP were analyzed using a model framework that integrates CH4MODwetland, TOPMODEL, and TEM models. Our simulation revealed a total increase of 15% in CH4 fluxes, from 6.1 g m−2 year−1 to 7.0 g m−2 year−1. This change was primarily induced by increases in temperature and precipitation. Although climate change has accelerated CH4 fluxes, the total amount of regional CH4 emissions decreased by approximately 20% (0.06 Tg—i.e., from 0.28 Tg in the 1950s to 0.22 Tg in the 2000s), due to the loss of 1.41 million ha of wetland. Spatially, both CH4 fluxes and regional CH4 emissions showed a decreasing trend from the southeast to the northwest of the study area. Lower CH4 emissions occurred in the northwestern Plateau, while the highest emissions occurred in the eastern edge. Overall, our results highlighted the fact that wetland loss decreased the CH4 emissions by approximately 20%, even though climate change has accelerated the overall CH4 emission rates over the last six decades.

Estimates of reservoir methane emissions based on a spatially balanced probabilistic‐survey

AbstractGlobal estimates of methane (CH4) emissions from reservoirs are poorly constrained, partly due to the challenges of accounting for intra‐reservoir spatial variability. Reservoir‐scale emission rates are often estimated by extrapolating from measurement made at a few locations; however, error and bias associated with this approach can be large and difficult to quantify. Here, we use a generalized random tessellation survey (GRTS) design to generate unbiased estimates of reservoir‐CH4 emissions rates (±95% CI) for areas below tributary inflows, open‐waters, and at the whole‐reservoir scale. Total CH4 emission rates (i.e., sum of ebullition and diffusive emissions) were 4.8 (±2.1), 33.0 (±10.7), and 8.3 (±2.2) mg CH4 m−2 h−1 in open‐waters, tributary‐associated areas, and the whole‐reservoir for the period in August 2014 during which 115 sites were sampled across an 7.98 km2 reservoir in Southwestern, Ohio, U.S.A. Tributary areas occupy 12% of the reservoir surface, but were the source of 41% of total CH4 emissions, highlighting the importance of riverine‐lacustrine transition zones. Ebullition accounted for > 90% of CH4 emission at all spatial scales. Overall, CH4 emission rates were high for a temperate zone reservoir, possibly because earlier studies underestimated ebullition or did not include emission hot spots. Confidence interval estimates that incorporated spatial pattern in CH4 emissions were up to 29% narrower than when spatial independence is assumed among sites. The use of GRTS, or other probabilistic survey designs, can improve the accuracy and precision of reservoir emission rate estimates, which is needed to better constrain uncertainty in global scale emission estimates.

Quantifying atmospheric methane emissions from oil and natural gas production in the Bakken shale region of North Dakota

AbstractWe present in situ airborne measurements of methane (CH4) and ethane (C2H6) taken aboard a NOAA DHC‐6 Twin Otter research aircraft in May 2014 over the Williston Basin in northwestern North Dakota, a region of rapidly growing oil and natural gas production. The Williston Basin is best known for the Bakken shale formation, from which a significant increase in oil and gas extraction has occurred since 2009. We derive a CH4 emission rate from this region using airborne data by calculating the CH4 enhancement flux through the planetary boundary layer downwind of the region. We calculate CH4 emissions of (36 ± 13), (27 ± 13), (27 ± 12), (27 ± 12), and (25 ± 10) × 103 kg/h from five transects on 3 days in May 2014 downwind of the Bakken shale region of North Dakota. The average emission, (28 ± 5) × 103 kg/h, extrapolates to 0.25 ± 0.05 Tg/yr, which is significantly lower than a previous estimate of CH4 emissions from northwestern North Dakota and southeastern Saskatchewan using satellite remote sensing data. We attribute the majority of CH4 emissions in the region to oil and gas operations in the Bakken based on the similarity between atmospheric C2H6 to CH4 enhancement ratios and the composition of raw natural gas withdrawn from the region.

Acidification of raw and co-digested pig slurries with alum before mechanical separation reduces gaseous emission during storage of solid and liquid fractions

Acidification of livestock slurries is used to reduce ammonia and methane emissions, and mechanical separation is applied to concentrate organic matter and nutrients in the resulting solid fraction (SF). The fractions obtained after separation are normally stored on farms during long periods before they can be applied to soil or transported to fields far away. During this storage period and/or transport, the emissions of ammonia and greenhouse gases (GHG) can be high, causing environmental problems.The aim of this study was to assess the effects of acidification before the separation of raw and co-digested pig slurries on the gaseous emissions during the storage of the resulting liquid fraction (LF) and SF. The emission rates of NH3, N2O, CO2, and CH4 were followed during 70days of storage.Acidification applied before separation significantly reduced the emissions of NH3 and GHG during the storage of the fractions from raw and co-digested slurries. The main reductions were observed in the acidified fractions, relative to the non-acidified fractions (that led to the highest gaseous emissions), in both slurries. Thus, NH3 and CH4 emissions were significantly reduced in acidified LFs and N2O emissions were significantly reduced in acidified SFs. The CO2 emissions were significantly reduced in both acidified fractions from both slurries, since most of the inorganic C was released during the acidification process.It can be concluded that acidification before separation is a good abatement practice to minimize ammonia emissions during separation and to reduce gaseous emissions during the storage of slurry fractions.

Enteric methane emissions and nitrogen utilisation efficiency for two genotype of hill hoggets offered fresh, ensiled and pelleted ryegrass

Thirty-six 12-month-old hill hoggets were used in a 2 genotype (18 Scottish Blackface vs. 18 Swaledale×Scottish Blackface)×3 diet (fresh vs. ensiled vs. pelleted ryegrass) factorial design experiment to evaluate the effects of hogget genotype and forage type on enteric methane (CH4) emissions and nitrogen (N) utilisation. The hoggets were offered 3 diets ad libitum with no concentrate supplementation in a single period study with 6 hoggets for each of the 6 genotype×diet combinations (n=6). Fresh ryegrass was harvested daily in the morning. Pelleted ryegrass was sourced from a commercial supplier (Aylescott Driers & Feeds, Burrington, UK) and the ryegrass silage was ensiled with Ecosyl (Lactobacillus plantarum, Volac International Limited, Hertfordshire, UK) as an additive. The hoggets were housed in individual pens for at least 14 d before being transferred to individual respiration chambers for a further 4 d with feed intake, faeces and urine outputs and CH4 emissions measured. There was no significant interaction between genotype and forage type on any parameter evaluated. Sheep offered pelleted grass had greater feed intake (e.g. DM, energy and N) but less energy and nutrient apparent digestibility (e.g. DM, N and neutral detergent fibre (NDF)) than those given fresh grass or grass silage (P<0.001). Feeding pelleted grass, rather than fresh grass or grass silage, reduced enteric CH4 emissions as a proportion of DM intake and gross energy (GE) intake (P<0.01). Sheep offered fresh grass had a significantly lower acid detergent fibre (ADF) apparent digestibility, and CH4 energy output (CH4-E) as a proportion of GE intake than those offered grass silage (P<0.001). There was no significant difference, in CH4 emission rate or N utilisation efficiency when compared between Scottish Blackface and Swaledale × Scottish Blackface. Linear and multiple regression techniques were used to develop relationships between CH4 emissions or N excretion and dietary and animal variables using data from sheep offered fresh ryegrass and grass silage. The equation relating CH4-E (MJ/d) to GE intake (GEI, MJ/d), energy apparent digestibility (DE/GE) and metabolisability (ME/GE) resulted in a high r2 (CH4-E=0.074 GEI+9.2 DE/GE−10.2 ME/GE−0.37, r2=0.93). N intake (NI) was the best predictor for manure N excretion (Manure N=0.66 NI+0.96, r2=0.85). The use of these relationships can potentially improve the precision and decrease the uncertainty in predicting CH4 emissions and N excretion for sheep production systems managed under the current feeding conditions.

Greenhouse gas emissions from oilfield-produced water in Shengli Oilfield, Eastern China

Greenhouse gas (GHG) emissions from oil and gas systems are an important component of the GHG emission inventory. To assess the carbon emissions from oilfield-produced water under atmospheric conditions correctly, in situ detection and simulation experiments were developed to study the natural release of GHG into the atmosphere in the Shengli Oilfield, the second largest oilfield in China. The results showed that methane (CH4) and carbon dioxide (CO2) were the primary gases released naturally from the oilfield-produced water. The atmospheric temperature and release time played important roles in determining the CH4 and CO2 emissions under atmospheric conditions. Higher temperatures enhanced the carbon emissions. The emissions of both CH4 and CO2 from oilfield-produced water were highest at 27°C and lowest at 3°C. The bulk of CH4 and CO2 was released from the oilfield-produced water during the first release period, 0–2hr, for each temperature, with a maximum average emission rate of 0.415gCH4/(m3·hr) and 3.934gCO2/(m3·hr), respectively. Then the carbon emissions at other time periods gradually decreased with the extension of time. The higher solubility of CO2 in water than CH4 results in a higher emission rate of CH4 than CO2 over the same release duration. The simulation proved that oilfield-produced water is one of the potential emission sources that should be given great attention in oil and gas systems.

Methane Emissions from Conventional and Unconventional Natural Gas Production Sites in the Marcellus Shale Basin.

There is a need for continued assessment of methane (CH4) emissions associated with natural gas (NG) production, especially as recent advancements in horizontal drilling combined with staged hydraulic fracturing technologies have dramatically increased NG production (we refer to these wells as "unconventional" NG wells). In this study, we measured facility-level CH4 emissions rates from the NG production sector in the Marcellus region, and compared CH4 emissions between unconventional NG (UNG) well pad sites and the relatively smaller and older "conventional" NG (CvNG) sites that consist of wells drilled vertically into permeable geologic formations. A top-down tracer-flux CH4 measurement approach utilizing mobile downwind intercepts of CH4, ethane, and tracer (nitrous oxide and acetylene) plumes was performed at 18 CvNG sites (19 individual wells) and 17 UNG sites (88 individual wells). The 17 UNG sites included four sites undergoing completion flowback (FB). The mean facility-level CH4 emission rate among UNG well pad sites in routine production (18.8 kg/h (95% confidence interval (CI) on the mean of 12.0-26.8 kg/h)) was 23 times greater than the mean CH4 emissions from CvNG sites. These differences were attributed, in part, to the large size (based on number of wells and ancillary NG production equipment) and the significantly higher production rate of UNG sites. However, CvNG sites generally had much higher production-normalized CH4 emission rates (median: 11%; range: 0.35-91%) compared to UNG sites (median: 0.13%, range: 0.01-1.2%), likely resulting from a greater prevalence of avoidable process operating conditions (e.g., unresolved equipment maintenance issues). At the regional scale, we estimate that total annual CH4 emissions from 88 500 combined CvNG well pads in Pennsylvania and West Virginia (660 Gg (95% CI: 500 to 800 Gg)) exceeded that from 3390 UNG well pads by 170 Gg, reflecting the large number of CvNG wells and the comparably large fraction of CH4 lost per unit production. The new emissions data suggest that the recently instituted Pennsylvania CH4 emissions inventory substantially underestimates measured facility-level CH4 emissions by >10-40 times for five UNG sites in this study.

Development of a method for estimating total CH4 emission from rice paddies in Japan using the DNDC-Rice model

Methane (CH4) is a greenhouse gas, and paddy fields are one of its main anthropogenic emission sources. To mitigate this emission based on effective management measures, CH4 emission from paddy fields must be quantified at a national scale. In Japan, country-specific emission factors have been applied since 2003 to estimate national CH4 emission from paddy fields. However, this method cannot account for the effects of weather conditions and temporal variability of nitrogen fertilizer and organic matter application rates; thus, the estimated emission is highly uncertain. To improve the accuracy of national-scale estimates, we calculated country-specific emission factors using the DeNitrification–DeComposition-Rice (DNDC-Rice) model. First, we calculated CH4 emission from 1981 to 2010 using 986 datasets that included soil properties, meteorological data, and field management data. Using the simulated site-specific emission, we calculated annual mean emission for each of Japan's seven administrative regions, two water management regimes (continuous flooding and conventional mid-season drainage), and three soil drainage rates (slow, moderate, and fast). The mean emission was positively correlated with organic carbon input to the field, and we developed linear regressions for the relationships among the regions, water management regimes, and drainage rates. The regression results were within the range of published observation values for site-specific relationships between CH4 emission and organic carbon input rates. This suggests that the regressions provide a simplified method for estimating CH4 emission from Japanese paddy fields, though some modifications can further improve the estimation accuracy.

Using Common Boundaries to Assess Methane Emissions: A Life Cycle Evaluation of Natural Gas and Coal Power Systems

SummaryThere is consensus on the importance of upstream methane (CH4) emissions to the life cycle greenhouse gas (GHG) footprint of natural gas systems, but inconsistencies among recent studies explain why some researchers calculate a CH4 emission rate of less than 1% whereas others calculate a CH4 emission rate as high as 10%. These inconsistencies arise from differences in data collection methods, data collection time frames, and system boundaries. This analysis focuses on system boundary inconsistencies. Our results show that the calculated CH4 emission rate can increase nearly fourfold not by changing the magnitude of any particular emission source, but by merely changing the portions of the supply chain that are included within the system boundary. Our calculated CH4 emission rate for extraction through pipeline transmission is 1.2% for current practices. Our model allows us to identify GHG contributors in the upstream supply chain, but also allows us to tie upstream findings to complete life cycle scenarios. If applied to the life cycles of power systems and assessed in terms of cumulative radiative forcing, the upstream CH4 emission rate can be as high as 3.2% before the GHG impacts from natural gas power exceed those from coal power at any point during a 100‐year time frame.

Methane and nitrous oxide emissions and their GWPs: research on different irrigation modes in a rice paddy field

CH4 and N2O emission fluxes from a rice paddy field were measured in the cold region of Heilongjiang under four irrigation modes (control irrigation, wet irrigation, intermittent irrigation, and flood irrigation) by the static chamber-gas chromatograph technique. The emission rates of CH4 and N2O were simultaneously monitored once a week. The net global warming potential (GWP) was calculated as CO2 equivalents. The CH4 and N2O emission peak appeared in the rice active growth period, while the emissions were reduced in the remaining period regardless of the irrigation method utilised. The CH4 emission under flood irrigation was the highest, whereas that of the wet irrigation was 27.2% lower; the control and the intermittent irrigation manifested a decrease by 34% and 48.2%, respectively. N2O emission under flood irrigation was 0.41 kg•hm−2 smaller than that in the intermittent irrigation, but it was higher than those in the control and wet irrigation, respectively. By applying water-saving irrigation techniques, the greenhouse gas emissions from paddy fields can be effectively decreased.

Methane Emission from Panki Open Dump Site of Kanpur, India

In developing countries, quantities of solid waste generation is increasing day by day and most of which is disposed off through landfilling and open dumping resulting into the release of significant quantities of GHG. CH4, the major gas produced by these activities, is known to cause global warming. The paper reports the estimates of CH4 calculated by using IPCC Default, FOD method and LandGEM model, version 3.02 from Panki open dump site of Kanpur, India. The annual average CH4 emission rates from Panki open dump site is found as 197.33, 24.27 and 25.14 Gg by IPCC Default method, FOD and LandGEM respectively for the period 2010-2030. The study reveals that IPCC Default method over estimate the result therefore it is not recommended for open dump site. however, LandGEM is recommended over FOD method for open dumps due to the fact that [a] estimates of CH4 emission is very near to GHG emission by FOD method [b] simplicity in model parameters [c] avoidance of over estimation, if parameters are calculated as per the actual site conditions. So the present study reveals that LandGEM provides better estimation compared to other method and the CH4 emission rate is found as 25.14 Gg/year for the Panki open dump site, Kanpur.The assessment of methane emission potential reveals the fact that upgrading the open dumps into landfill increases the methane emission rates and their utilization potential and adding the landfill to fill the future needs and utilization of landfill gases.

Plant-mediated methane and nitrous oxide fluxes from a carex meadow in Poyang Lake during drawdown periods

Plants have been suggested to have significant effects on methane (CH4) and nitrous oxide (N2O) fluxes from littoral wetlands, but it remains unclear in subtropical lakes. We conducted in situ measurement of CH4 and N2O fluxes for two years. To distinguish between the effects of shoots and roots, three treatments (i.e., intact plants as control, shoot clipping, and root exclusion) were used. Effects of plant biomass, temperature, and soil moisture on CH4 and N2O fluxes were analyzed. The mean ecosystem CH4 emission rate was 36 μg CH4 m−2 h−1 for drying periods, but 8219 μg CH4 m−2 h−1 for drying-wetting transition periods. CH4 fluxes were positively correlated with below-ground and total biomass, but not with above-ground biomass. Clipping did not significantly alter CH4 flux rate, but root exclusion decreased the CH4 flux by 116 % as compared to the control. N2O emissions were similar for both the drying and drying-wetting transition periods, with a mean rate of 20 μg N2O m−2 h−1. Both clipping and root exclusion significantly increased N2O fluxes as compared to the control. There was no significant correlation between CH4 and N2O fluxes. Roots dominated plant-mediated enhancement in CH4 fluxes, but played almost an equal role as shoots in plant-regulated suppression on N2O fluxes in this Carex meadow during drawdown periods.

Effective Suppression of Methane Emission by 2-Bromoethanesulfonate during Rice Cultivation.

2-bromoethanesulfonate (BES) is a structural analogue of coenzyme M (Co-M) and potent inhibitor of methanogenesis. Several studies confirmed, BES can inhibit CH4 prodcution in rice soil, but the suppressing effectiveness of BES application on CH4 emission under rice cultivation has not been studied. In this pot experiment, different levels of BES (0, 20, 40 and 80 mg kg-1) were applied to study its effect on CH4 emission and plant growth during rice cultivation. Application of BES effectively suppressed CH4 emission when compared with control soil during rice cultivation. The CH4 emission rates were significantly (P<0.001) decreased by BES application possibly due to significant (P<0.001) reduction of methnaogenic biomarkers like Co-M concentration and mcrA gene copy number (i.e. methanogenic abunadance). BES significantly (P<0.001) reduced methanogen activity, while it did not affect soil dehydrogenase activity during rice cultivation. A rice plant growth and yield parameters were not affected by BES application. The maximum CH4 reduction (49% reduction over control) was found at 80 mg kg-1 BES application during rice cultivation. It is, therefore, concluded that BES could be a suitable soil amendment for reducing CH4 emission without affecting rice plant growth and productivity during rice cultivation.

The effects of slatted floors and manure scraper systems on the concentrations and emission rates of ammonia, methane and carbon dioxide in goat buildings

This study was designed to quantify the concentrations and emission rates of ammonia (NH3), methane (CH4) and carbon dioxide (CO2) and to evaluate their effects on the indoor environment of slatted floor and manure scraper systems in two goat buildings. One building had a slatted floor and a manure scraper system (building II); the other building did not, and manure removal was performed by workers (building I). This study was conducted from April 2014 until January 2015, with sampling during four seasons. The NH3, CH4 and CO2 emission rates were highest in the summer and lowest in the winter in both buildings. However, in building II, these emission rates were significantly lower (P<0.05) than those in building I in each season. In both buildings, the NH3, CH4 and CO2 concentrations were highest in the winter and lowest in the summer, although the gas concentrations were significantly lower (P<0.05) in building II than in building I. The results of this study suggest that the slatted floor and manure scraper systems substantially lower the emissions of harmful gases in goat buildings.