Closed Chamber Method Research Articles

Assessing the Impact of Climate Change on Methane Emissions from Rice Production Systems in Southern India

The impact of climate change on methane (CH4) emissions from rice production systems in the Coimbatore region (Tamil Nadu, India) was studied by leveraging field experiments across two main treatments and four sub-treatments in a split-plot design. Utilizing the closed-chamber method for gas collection and gas chromatography analysis, this study identified significant differences in CH4 emissions between conventional cultivation methods and the system of rice intensification (henceforth SRI). Over two growing seasons, conventional cultivation methods reported higher CH4 emissions (range: from 36.9 to 59.3 kg CH4 ha−1 season−1) compared with SRI (range: from 2.2 to 12.8 kg CH4 ha−1 season−1). Experimental data were subsequently used to guide parametrization and validation of the DeNitrification–DeComposition (DNDC) model. The validation of the model showed good agreement between the measured and modeled data, as denoted by the statistical tests performed, which included CRM (0.09), D-index (0.99), RMSE (7.16), EF (0.96), and R2 (0.92). The validated model was then used to develop future CH4 emissions projections under various shared socio-economic pathways (henceforth SSPs) for the mid- (2021–2050) and late (2051–2080) century. The analysis revealed a potential increase in CH4 emissions for the simulated scenarios, which was dependent on specific soil and irrigation management practices. Conventional cultivation produced the highest CH4 emissions, but it was shown that they could be reduced if the current practice was replaced by minimal flooding or through irrigation with alternating wetting and drying cycles. Emissions were predicted to rise until SSP 370, with a marginal increase in SSP 585 thereafter. The findings of this work underscored an urgency to develop climate-smart location-specific mitigation strategies focused on simultaneously improving current water and nutrient management practices. The use of methanotrophs to reduce CH4 production from rice systems should be considered in future work. This research also highlighted the critical interaction that exists between agricultural practices and climate change, and emphasized the need to implement adaptive crop management strategies that can sustain productivity and mitigate the environmental impacts of rice-based systems in southern India.

The Effect of the Use of a Novel Urease Inhibitor Coated Urea on the Greenhouse Gas Emissions and Ammonia Volatilization Losses from a Maize Field

Nitrogen fertilizers are essential for enhancing agricultural productivity but are also major contributors to greenhouse gas (GHG) emissions and ammonia volatilization, which affect environmental sustainability. This study evaluated the effect of cashew nut shell liquid (CNSL)-coated urea on GHG emissions and ammonia losses from maize fields in the Indo-Gangetic Plains, known for excessive nitrogen fertilizer usage. A randomized block design was employed with four treatments: control (no nitrogen), prilled urea, neem-coated urea (NCU), and CNSL-coated urea (CCU). Gas samples were collected using the closed chamber method, and emissions of CO₂ and N₂O were analyzed via gas chromatography. Ammonia volatilization was measured using the forced air draft method. Results showed that the CCU treatment significantly reduced ammonia volatilization compared to prilled urea (15.84% reduction), with reductions of 9% to those observed with NCU. Moreover, CCU-treated plots exhibited reduced cumulative GHG and lower global warming potential (GWP) without compromising maize yields. Cumulative GHG emissions varied among the treatments in the order urea> CCU> NCU> Control. CCU treated plots exhibited a net GWP decrease of 8.59% compared to urea and an increase of 4.13% compared to NCU. These findings suggest that CNSL-coated urea can serve as an eco-friendly alternative to conventional urea, potentially mitigating environmental impacts associated with nitrogen fertilization. Further studies are recommended to assess the long-term efficacy of CNSL in various soil types and climatic conditions.

Contact dermatitis secondary to povidone-iodine: A systematic review.

Cutaneous reactions to povidone (PVP)-iodine are widely reported; however, distinction between allergic and irritant reactions can be challenging. Free iodine is responsible for irritant reactions and is released when PVP-iodine is in a liquid state. The aim of this study was to review the clinical presentation and results of patch testing in patients with PVP-iodine contact dermatitis. A systematic review was conducted by searching Pubmed, MEDLINE, and Google Scholar databases for reports of contact dermatitis secondary to PVP-iodine. Data were collated including study design, patient age and gender identity, iodine exposure, skin biopsy findings, and patch test methodology and results. The search revealed 187 reports with 38 eligible studies; 30 case reports/case series and 8 retrospective cohort studies. Overall, there were 223 patients with PVP-iodine contact dermatitis. The commonest reaction was irritant contact dermatitis (51%), followed by allergic contact dermatitis (40%) and contact dermatitis not further specified (9%). Irritant reactions were characterised by burn-like morphology and, when due to surgical skin disinfectant, were often distant from the surgical incision site. Patch testing was most often performed with a 10% PVP-iodine aqueous solution; however, irritant reactions in controls occur. Various testing methods including iodine in petrolatum, ethanol, dried powder, and open application testing were described. Most reactions to PVP-iodine are irritant and patch testing using a closed-chamber method yields inconsistent results due to risk of irritation from free iodine release over the 2-day occlusion time. Surgeons should be aware of the risk of prolonged skin contact with wet iodine solution.

Effects of Fallow Season Water and Straw Management on Methane Emissions and Associated Microorganisms

The effects of fallow season water and straw management on methane (CH4) emissions during the fallow season and the subsequent rice-growing season are rarely reported, and the underlying microbial mechanisms remain unclear. A field experiment was conducted with four treatments: (1) fields flooded in both the fallow and rice seasons (FF), (2) fields drained in the fallow season and flooded in the rice season (DF), (3) FF with straw retention (FFS), and (4) DF with straw retention (DFS). The CH4 emissions in fields under different water and straw treatments were monitored using the static closed chamber method. Methanogenic and methanotrophic communities in these fields were examined using terminal restriction fragment length polymorphism (T-RFLP) analysis based on the mcrA gene and pmoA gene encoding methyl coenzyme M reductase and particulate methane monooxygenase, respectively. The results showed that CH4 emissions were significantly affected by water management, straw retention, season, and their interactions. Over 80% of CH4 emissions occurred during the rice season. Field drainage during the fallow season reduced CH4 emissions by 47.0% and 53.8% with and without straw during the rice season, respectively. Water management altered the abundance and composition of methanogens and methanotrophs, whereas the effects of straw retention were less pronounced. The quantitative polymerase chain reaction (qPCR) assay revealed that field drainage in the fallow season decreased the mcrA gene abundance by 30.0% and 23.2% with and without straw in rice season, respectively, and increased the pmoA gene abundance by 108.9% and 213.7% with and without straw in rice season, respectively. CH4 flux was significantly positively associated with mcrA gene copy number and the ratio of mcrA to pmoA gene copy number, whereas it was significantly negatively correlated with the pmoA gene copy number. Results indicated that fallow drainage greatly decreased CH4 emission not only during the fallow season but also during the subsequent rice season by altering the community composition of methanogens and methanotrophs. These findings provide scientific insight into the role of water and straw management in controlling CH4 emissions through microbial community dynamics.

Assessing sediment CO2 effluxes in the coastal ecosystem of North Sumatra, Indonesia

Coastal wetlands including mangrove play a vital role in regulating the local and global carbon cycle. Coastal areas contribute greatly to the carbon exchange process due to the complex interactions that occur between the atmosphere, land, and oceans. One of the important components in coastal carbon dynamics is CO2 gas exchange between soil, water and the atmosphere. This study aims to assess CO2 efflux across various land covers (namely natural mangrove, restored mangrove, and converted mangroves to oil palm and aquaculture pond) in the coastal areas of North Sumatra Province, and analyze the effect of sea tides and ebbs on the rate of CO2 efflux and their connection with the number and area of macrozoobenthos burrows. We applied direct sampling by using the static closed chamber method attached to portable CO2 analyzer. The mean of CO2 efflux in natural mangrove forest land covers was 866±585 mgCO2/m2/h during low tide conditions and 1137±792 mgCO2/m2/h during high tide conditions, followed by oil palm plantations at 760.71±341 mgCO2/m2/h, restored mangroves during low tide of 575.24±326 mgCO2/m2/h and 597.11±180 mg CO2/m2/h during high tide conditions, and the lowest was recorded in ponds at 588.55±358 mgCO2/m2/h. Further, we observed that tidal conditions affect the magnitudes of CO2 efflux in natural and restored mangrove forests, and we did not observe similar pattern in oil palms and ponds since these land covers were not influenced by regular tidal input. We also observed that no significant relationship between the number and area of macrozoobenthos burrows and CO2 efflux. Our findings suggest that CO2 effluxes in coastal wetlands are highly dynamic and presumably driven by complex factors and therefore, understanding their magnitudes and drivers requires extensive measurement covering large spatial and temporal scales.

MODELLING THE IMPACT OF SOIL AND METEOROLOGICAL PA-RAMETERS ON CARBON DYNAMICS IN WETLAND ECOSYSTEMS

Wetlands are characterised by distinct hydrological regimes and have significant importance in the global carbon cycle, having the potential to reduce carbon emissions through long-term carbon storage in the soil. In this study, carbon dynamics were simulated using a process-based model DeNitrification-DeComposition (DNDC), for two locations along Dâmbovița River case study area. These scenarios took into consideration the interconnection of soil parameters, hydrology, meteorological conditions and vegetation type. The findings showed that soil CO2 emissions are positively and strongly correlated with air temperature and soil moisture, with changes in the water content of the soil regime having the greatest impact on CO2 fluxes. Also, the model simulations have been validated by statistical analysis of uncertainties with the values of CO2 fluxes measured in situ using the dynamic closed chamber method. By comparing DNDC outputs with field measurements, the performance of the model was evaluated in different environmental conditions and the results were consistent, which increased confidence in its application for assessing wetland ecosystems. These results contribute to a more comprehensive understanding of the carbon cycle in wetlands and an improved estimation of the effects of climate change on the dynamics of carbon in these ecosystems.

Greenhouse Gas Fluxes from Cranberry and Highbush Blueberry Plantations on Former Peat Extraction Fields Compared to Active Peat Extraction Fields and Pristine Peatlands in Latvia

Emissions of carbon dioxide (CO2), nitrous oxide (N2O), and methane (CH4), particularly those from organic soils, need to be reduced in the context of climate change mitigation (CCM). Here, we estimated the greenhouse gas (GHG) fluxes from nutrient-poor organic soils in cranberry (Vaccinium macrocarpon) and highbush blueberry (Vaccinium corymbosum) plantations established on former peat extraction fields compared to active peat extraction fields and pristine raised bogs in Latvia. A two-year study (2016–2018) was conducted using the manual closed chamber method. In berry plantations and active peat extraction fields, annual net CO2 fluxes contributed the most to total GHG emissions, accounting for over 67%, and temperature had the most significant impact on CO2 fluxes. Conversely, annual CH4 fluxes were the primary contributor to total net GHG emissions in the pristine raised bog, which simultaneously acted as a slight CO2 sink. N2O fluxes were relatively low among all studied land use types. This study provided quantitative insights into the variation in GHG fluxes and the environmental variables influencing them, and the obtained data are valuable to estimate the impact of the establishment of berry plantations on former peat extraction fields on CCM in the hemiboreal region of Europe.

Greenhouse Gas Emissions from a 20-Year-Old Restored Peatland

Peatlands are ecosystems with unique hydrological and ecological properties that serve as critical carbon reservoirs, helping facilitate the reduction of greenhouse gases (GHG). In Canada, the peat industry uses vacuum harvesting to extract peat for horticultural use. This disturbs the natural ecosystem, increasing CO2 and decreasing CH4 emissions due to complete removal of surface vegetation and lowering of the water table. Following years of extraction, if these peatlands are not properly restored, GHG emissions will increase, negatively impacting the climate. The moss layer transfer technique (MLTT) is the primary method for restoring peatlands in Canada. The MLTT allows peatlands to regain their natural ecosystem function and to reaccumulate peat. This is done by revegetation of key species including sphagnum moss, and rewetting of the peatland through the blockage of drainage ditches. My research project investigates a peatland in Pointe-Lebel, Quebec restored in 2004 using MLTT following vacuum extraction. I used the closed chamber method to measure the CO2 and CH4 exchanges at the plant community scale and three repetitions of each of moss, shrubs, and cotton grass communities were followed throughout the summer. Wells at each collar provided the water table depth; a controlling variable for GHG fluxes. I conducted a vegetation survey at peak plant productivity to characterize the proportions of the plant communities and to allow chamber measurements of GHG to be scaled by the contribution of each plant community. If successful, a restored peatland will be a net sink of carbon. Preliminary data analysis at this 20-year-old restored site indicates a net CO2 sink during the summer of 2024. My data also suggests that the site is a small source of CH4. The results from my project will aid in advancing research on peatlands, stressing the importance of taking the proper steps towards restoration.

CO2-emission from arable chernozems of western Nransbaikalia

CO2-Emissions from agrochernozems of dispersed carbonateTugnuibasin and agrochernozems of quasi-clayYeravninsky basin of westernTransbaikaliawere studied.To compareCO2-emissions from soils, the virginland variants of the same name are taken.The aimof the study is to quantify and comparatively evaluate theproduction of carbon dioxide from arable chernozems with contrasting temperatureand moisture conditions.The measurement ofCO2fluxes from thesoil was carried out by a closed chamber method witha portable infraredCO2gas analyzerAZ7752 (AZInstrumentCorp.,Taiwan).CO2-emissions were largely dependent on hydrothermalconditions.Its minimum at the beginning of the growing seasonwas associated with the effect of low soil temperatures, themaximum was more often noted after precipitation.The peaks ofCO2-emissions coincided with an increase in temperature and humidityfromJune to earlyAugust, in conditions of a lackof readily available moisture, and were also associated with ahumidification regime.The limiting factor of theCO2flux forquasi-clay chernozems was the soil temperature, for dispersed carbonate chernozems–humidity.It has been established that the totalCO2-emission in arable soils is significantly less than in virginsoils, this is explained by the peculiarities of the agrogenicenvironment.Arable soils are warmer in summer, and they cooldown more and deeper in winter.The transformation of thewater regime occurs in the direction of reducing moisture andincreasing its contrast during the warm period.The total carbonloss index varies in a series: dispersed-carbonate chernozem→quasi-claychernozem, virgin soil→arable land.

Effects of Rodent Isolation on Plant Community Structure and Greenhouse Gas Emission in the Alpine Grassland of the Qinghai–Tibet Plateau

As one of the dominant species of the alpine grassland on the Qinghai–Tibet Plateau, the activities (e.g., gnawing, burrowing, and grass storage) of plateau pikas (Ochotona curzoniae) directly alter the plant community structure of the grassland ecosystem and affect livestock production and greenhouse gas emission. In order to investigate the effects of rodent isolation (RI) on plant community structure and greenhouse gas emission in the alpine grassland of the Qinghai–Tibet Plateau, we established plots of rodent isolation and rodent activity (i.e., the control sample (CK)) in the 14th village, Seni District, Nagqu City in May 2018. From July 2019 to September, the numbers, sizes, and total damaged area of effective holes; the height, coverage, and aboveground plant biomass; and the methane (CH4) and nitrous oxide (N2O) emissions of the alpine grassland were monitored by the quadrat survey method and static closed-chamber method. The results show that the invasion and tunneling of Ochotona curzoniae resulted in the destruction of alpine grassland measuring 0.064 m2 per square meter, while the rodent isolation plots showed that 97.9% of the alpine grassland remained unaltered; such unaffected land implies that the economic income of herdsmen could increase by 140 CNY hm−2. The rodent isolation plots also show that the height and proportion of grasses and sedges in the alpine grassland increased, while the proportion of poisonous weeds decreased. Moreover, the rodent isolation plots also showed a significantly increased coverage of aboveground biomass (p < 0.05), although species richness showed no significant effect based on the Shannon–Weiner, Simpson, and Pielou indices (p > 0.05). The soil uptake of CH4 and N2O was 204.99 ± 50.23 μg m−2 h−1 and 4.48 ± 1.02 μg m−2 h−1 in the rodent isolation plots, significantly higher by 465.75% and 3001.4% relative to the rodent activity plots, respectively (p < 0.05). Therefore, the establishment of rodent isolation areas can effectively alleviate the degree of damage to alpine grasslands in the short run and slow down the greenhouse gas emission rate to some extent. However, excessive rodent control may also have negative effects on grassland ecosystems, so more attention should be paid in future studies to determining the disturbance threshold of plateau pika in this area. These results provide theoretical guidance for rodent control, grassland protection, and ecological environment management on the Qinghai–Tibet Plateau.

Impacts of LNAPL types on mechanisms and rate of natural source zone depletion

Understanding the mechanisms of natural source zone depletion (NSZD) will support an improved understanding of the long-term sustainability of NSZD as a site remedy and how NSZD rates may change over time. This is the first study that has quantified and compared the rate of three NSZD mechanisms (methanogenesis, vaporization, and aqueous biodegradation) between two chemically distinct light non-aqueous phase liquid (LNAPL) source zones (aliphatic-rich naphtha for Zone #1 vs aromatic-rich pyrolysis gasoline for Zone #2) within the same geologic and climate conditions. The rates of NSZD attributable to vaporization (400 mg C/m2/d vs. 300 mg C/m2/d) and aqueous biodegradation (92 mg C/m2/d vs. 67 mg C/m2/d) were similar for Zone #1 and #2; however, the rate of methanogenesis NSZD was 6x higher in Zone #1 (1000 mg C/m2/d vs. 170 mg C/m2/d). These results suggest that the aliphatic hydrocarbons content in an LNAPL source may be a factor in the rate of methanogenesis NSZD. For both Zone #1 and #2, total NSZD rate determined using this “three mechanism” measurement method was in reasonable agreement with two other methods used to measure total NSZD rates (CO2 Gradient Method and Dynamic Closed Chamber Method), validating the “three mechanism” method as a tool to measure the total NSZD rate at a site and to provide an improved understanding of the predominant NSZD mechanism. Overall, this study highlights the importance of LNAPL type and chemical characteristics in determining source zone natural attenuation mechanism and its total rates.

Assessing methane emissions from paddy fields through environmental and UAV remote sensing variables.

Concerns about methane (CH4) emissions from rice, a staple sustaining over 3.5 billion people globally, are heightened due to its status as the second-largest contributor to greenhouse gases, driving climate change. Accurate quantification of CH4 emissions from rice fields is crucial for understanding gas concentrations. Leveraging technological advancements, we present a groundbreaking solution that integrates machine learning and remote sensing data, challenging traditional closed chamber methods. To achieve this, our methodology involves extensive data collection using drones equipped with a Micasense Altum camera and ground sensors, effectively reducing reliance on labor-intensive and costly field sampling. In this experimental project, our research delves into the intricate relationship between environmental variables, such as soil conditions and weather patterns, and CH4 emissions. We achieved remarkable results by utilizing unmanned aerial vehicles (UAV) and evaluating over 20 regression models, emphasizing an R2 value of 0.98 and 0.95 for the training and testing data, respectively. This outcome designates the random forest regressor as the most suitable model with superior predictive capabilities. Notably, phosphorus, GRVI median, and cumulative soil and water temperature emerged as the model's fittest variables for predicting these values. Our findings underscore an innovative, cost-effective, and efficient alternative for quantifying CH4 emissions, marking a significant advancement in the technology-driven approach to evaluating rice growth parameters and vegetation indices, providing valuable insights for advancing gas emissions studies in rice paddies.

Effects of nitrogen and water addition on ecosystem carbon fluxes in a heavily degraded desert steppe

Changes in global precipitation patterns and increased nitrogen (N) deposition have important effects on the dynamics of the carbon (C) cycle in grassland ecosystems. Long-term overgrazing caused heavy degradation of grasslands and more than 60 % of China’s natural grasslands experienced moderate to severe degradation. To elucidate the effects of increasing precipitation and N deposition on C fluxes in a desert steppe ecosystem, experiments with nitrogen and water addition were conducted with four treatments, i.e., control (CK), N addition (N), water addition (W), combined addition of N and water (NW), in a Stipa breviflora desert steppe that had been heavily degraded. The ecosystem CO2 fluxes, including gross ecosystem productivity (GEP), net ecosystem CO2 exchange (NEE), and ecosystem respiration (ER), were determined using the closed chamber method during the growing seasons (May–October) of 2019 and 2020. Our results showed that water and nitrogen addition did not change the patterns of the seasonal dynamics of the ecosystem CO2 fluxes, indicating that water is the main limiting factor of CO2 fluxes in the studied desert steppe ecosystem. Precipitation increase (both W and NW treatments) stimulated all three components of the ecosystem CO2 fluxes, but N addition alone enhanced NEE and GEP while had no significant effects on ER, indicating water-induced increase of GEP was caused by both NEE and ER while N-induced increase of GEP was mainly caused by increases of NEE. Water addition can increase the effectiveness of N addition, but there was little interaction between the two factors. Soil moisture was more significantly correlated than soil temperature with ecosystem CO2 fluxes, and water addition could further enhance the correlation of ecosystem CO2 fluxes with soil temperature and moisture. Overall, ecosystem CO2 fluxes are more sensitive to the precipitation increase than to the N addition. These findings indicate that water supply will play more important role in ecosystem productivity of the desert steppe under the predicted scenarios of precipitation increase and increasing N deposition, which also provides scientific evidence for the restoration of those degraded desert steppe induced by overgrazing can not be achieved simply by increasing soil N availability.

Agro-technologies for greenhouse gases mitigation in flooded rice fields for promoting climate smart agriculture

We investigated methane (CH4) and nitrous oxide (N2O), two important greenhouse gases (GHGs) emissions using the closed chamber method from a flooded rice field in Brahmaputra valley of Assam, northeast part of India. We tried to understand the factors responsible for the emission and identify appropriate agro-technologies for their mitigation. Various factors like water level, drainage management, soil organic carbon management, crop management, fertilizer amendment, cultivar type etc. affect the GHG production and emission from the flooded rice soil. In this study, six treatments were employed, namely, farmer's practice (FP), recommended fertilizer dosage (RDF), direct seeded rice (DSR), intermittent wetting drying (IWD), use of efficient methanotrophs (MTH), and use of ammonium sulfate as a nitrogen source for real-time nitrogen management using leaf color chart, (AS). GHG flux was measured through the static closed chamber technique. Soil temperature, pH, and redox potential (Eh) and other soil physico-chemical and biological properties that have a potential role in GHG emission were also assessed. The lowest CH4 flux was observed in IWD treatment. The highest CH4 but lowest N2O flux was observed in RDF thus portraying a tradeoff relationship among these two GHGs. The highest N2O flux was observed in AS. Changes in Eh strongly altered CH4 and N2O emissions. The CH4 flux for the growing season varied from 62.5 to 86.3 kg ha−1 with an average of 72.4 kg ha−1. The average N2O flux was 0.89 kg ha−1 with values fluctuating between 0.72 – and 1.08 kg ha−1. The findings of this study could assist in understanding the factors affecting the source, production, and sink of these two important GHGs. IWD, along with judicious N-based fertilizer use, could provide significant respite from GHG emissions in rice-based agriculture. These climate-smart strategies not only reduce emissions but also have the potential to improve yield.

Pemberian Biochar Arang Kayu dan Tandan Kosong Sawit terhadap Gas N2O pada Tanah Gambut yang Ditumbuhi Kelapa Sawit

Peatlands are developed for agricultural cultivation, such as oil palm. The agricultural sector contributes 13.5% of the total greenhouse gas (GHG) emissions. Emissions from this sector are generally in the form of N2O 46%, CH4 45%, and CO2 9%. Recently, the focus on the development of peatlands for this activity has been so great, especially in relation to emissions of nitrous oxide (N2O). The potential for peatland to be used as agricultural land must pay attention to environmental aspects such as the level of N2O emissions. This study aims to determine the effect of wood activated to empty palm oil fruit bunches on N2O emissions from peatlands oil palm. This study used an allocation block design. The factors studied were the distribution of wood charcoal and empty palm oil bunches at 6 levels, namely: wood charcoal + 0 kg of empty palm fruit bunches; wood charcoal 0.75 kg + 0.75 kg of empty palm fruit bunches, and 0.375 empty palm fruit bunches+0.375 kg of wood charcoal; empty palm fruit bunch charcoal 1.5 kg+wood charcoal 1.5 kg. N2O gas was analyzed using the closed chamber method and the soil was analyzed for soil pH and field water capacity. The treatment was repeated 3 times, resulting in 18 experimental units. The results showed that on day 0, the application of wood charcoal and empty palm oil bunches did not affect N2O emissions, but on the 15 and 45 days. The results showed that the treatment affected N2O emissions.

Environmental and Management Drivers of Carbon Dioxide and Methane Emissions From Actively‐Extracted Peatlands in Alberta, Canada

AbstractThe installation of drainage ditches and removal of vegetation in preparation for vacuum harvesting alters the carbon dynamics of peatlands. However, we lack the measurements to understand the spatial distribution and environmental and substrate quality controls of carbon dioxide (CO2) and methane (CH4) emissions, as well as how these factors change over the 20–30 year extraction period. For three summers, we measured CO2 and CH4 emissions using the closed chamber method at three actively extracted peatlands near Drayton Valley, Alberta, ranging from 2 to 28 years since the start of extraction. Measurements were made in the ditches, and on segments of peat (fields) between adjacent ditches. Field emissions did not change with distance from ditches, likely due to the observed homogeneity of volumetric water content (VWC) and temperature across the fields. Understanding carbon dynamics in the ditches will be important, as they emitted on average two and 10 times, respectively, the amount of CO2 and CH4 per square meter of the fields. We found moderate to weak relationships between carbon emissions and soil temperature, VWC and ditch water level, though ditch emissions were significantly reduced when there was standing water present. Altering conventional site management, such as increasing ditch spacing, could substantially reduce CH4 emissions from the managed area. Emissions did not decrease with time since start of extraction. We suggest that Canadian emission factor calculations for land‐based emissions consider both peat quality variations among sites, and a site's extraction duration, which has been important in other studies.

Integrated water management practice in tropical peatland agriculture has low carbon emissions and subsidence rates

Hydrological management in the use of peatland for agriculture is the backbone of its sustainability and a critical factor in climate change mitigation. This study evaluates the application of an integrated water management practice known as the “Water Management Trinity” (WMT), implemented since 1986 on a coconut plantation on the eastern coast of Sumatra, in relation to CO2 emissions and subsidence rates. The WMT integrates canals, dikes, and dams with water gates to regulate water levels for both coconut agronomy and the preservation of the peat soil. The WMT has successfully regulated and maintained an average yearly water table depth of −45 to −51 cm below the surface. The methodology involved a closed chamber method for measuring soil CO2 flux using a portable Infrared Gas Analyzer, conducted weekly over a six-month period to cover dry and rainy season at bi-modal climate condition. Subsidence measurements have been ongoing from 1986 to 2022. The results show bare peat soil has heterotrophic respiration CO2 emissions of 7.77 t C–CO2 ha−1 yr−1, while in coconut plantations 7.99 t C–CO2 ha−1 yr−1, similar to emissions in mineral soils. Autotrophic respiration leads to the overestimation of CO2 emissions on peatland and accounts for 212–424% of the total emissions. The cumulative subsidence from 1986 to 2022 is −56.3 cm, with a soil rise of +0.8 cm in 2022, indicating a flattening rate of subsidence. This is characterized by an increase in bulk density at the surface from 0.072 to 0.144 gr/cm3, with approximately 81% of the subsidence being due to compaction. The statistical analysis found no relationship between water table depth and CO2 emissions, indicating that water table depth cannot be used as a predictor for CO2 emissions. In summary, peatland agriculture has a promising future when managed sustainably using an integrated hydrological management system.

A simple method to measure methane emissions from indoor gas leaks.

From wellhead to burner tip, each component of the natural gas process chain has come under increased scrutiny for the presence and magnitude of methane leaks, because of the large global warming potential of methane. Top-down measures of methane emissions in urban areas are significantly greater than bottom-up estimates. Recent research suggests this disparity might in part be explained by gas leaks from one of the least understood parts of the process chain: behind the gas meter in homes and buildings. However, little research has been performed in this area and few methods and data sets exist to measure or estimate them. We develop and test a simple and widely deployable closed chamber method that can be used for quantifying indoor methane emissions with an order-of-magnitude precision which allows for screening of indoor large volume ("super-emitting") leaks. We also perform test applications of the method finding indoor leaks in 90% of the 20 Greater Boston buildings studied and indoor methane emissions between 0.02-0.51 ft3 CH4 day-1 (0.4-10.3 g CH4 day-1) with a mean of 0.14 ft3 CH4 day-1 (2.8 g CH4 day-1). Our method provides a relatively simple way to scale up indoor methane emissions data collection. Increased data may reduce uncertainty in bottom-up inventories, and can be used to find super-emitting indoor emissions which may better explain the disparity between top-down and bottom-up post-meter emissions estimates.

Estimation of Heterotrophic Soil Respiration Response to the Summer Precipitation Regime and Different Depths of Snow Cover in a Temperate Continental Climate

Regime of precipitation and temperature conditions are key factors that regulate the rate of decomposition of soil organic matter in terrestrial ecosystems. The aim of this work was to assess the effect of the duration of dry periods in summer and different depths of snow cover in winter on heterotrophic soil respiration. The studies were carried out as part of a 2–year field manipulation experiment organized on gray soil (Haplic Luvisol) in the temperate continental climate conditions (southern Moscow region). Three variants were organized: (1) simulation of mild weather with uniform watering of the soil in summer and the absence of freezing in winter, (2) simulating two summer dry periods lasting 1–2 months with natural winter snow cover, (3) simulation of extreme weather with one long (~3 months) dry period in summer and complete removal of snow cover in winter. Heterotrophic soil respiration was measured by the closed chamber method on bare fallow during 2 years of continuous experiment and 1 more year after its completion. Medians of heterotrophic soil respiration for the entire period of the experiment in the three above–mentioned variants of the experiment were 38, 27 and 19 mg C/(m2 h), respectively. Two short dry periods led to an increase in heterotrophic soil respiration by 7–10%, which is associated both with the drying and rewetting cycles of the soil and with an increase in the average summer temperature of a 20–cm soil profile by 1.5°C. The prolonged dry period caused a decrease in heterotrophic soil respiration by 12–16% as a result of low soil moisture. Soil freezing led to a strong decrease in winter CO2 emission from soil, which reached 34–55% in the control variant and 57–72% when the snow cover was removed. The frost period (November–March) contributed from 25–34% without of soil freezing to 14–19% when its presence to the annual CO2 flux. We conclude that the change in the winter temperature regime of the soil due to manipulations with the snow depth led to a more significant change in the annual heterotrophic soil respiration than the lack of precipitations in the summer season.

Impact of Water Management on Methane Emission Dynamics in Sri Lankan Paddy Ecosystems

Paddy ecosystems constitute a dominant source of greenhouse gases, particularly of methane (CH4), due to the continuous flooding (CF) practiced under conventional paddy cultivation. A new management method, namely alternative wetting and draining (AWD) (i.e., flooding whenever surface water levels decline to 15 cm below the soil surface), is an emerging practice developed to mitigate CH4 emissions while providing an optimal solution for freshwater scarcity. Despite extensive paddy cultivation in Sri Lanka, no systematic research study has been conducted to investigate CH4 emissions under different water management practices. Thus, field experiments were conducted in Sri Lanka to investigate the feedback of controlled water management on seasonal and diel variation of CH4 emission, water consumption, and crop productivity. Adopting the same rice variety, two water management methods, continuous flooding (CF) and alternative wetting and draining (AWD), were compared with plants (W/P) and without plants (N/P) present. The emission of CH4 was measured using the static closed chamber method. The results show a 32% reduction in cumulative CH4 emission, on average, under AWD when compared to CF. The yield under the AWD was slightly higher than that of CF. Although it was not statistically significant (p > 0.05) there was not any reduction in yield in AWD than in CF. The total water saving under AWD ranged between 27–35% when compared to CF. Thus, the results support (without considering the effect of nitrous oxide) AWD as a promising method for mitigating CH4 emissions while preserving freshwater and maintaining grain yield in paddy systems.