Chamber Method Research Articles

Impacts of leaks and gas accumulation on closed chamber methods for measuring methane and carbon dioxide fluxes from tree stems

Accurate measurements of methane (CH4) and carbon dioxide (CO2) fluxes from tree stems are important for understanding greenhouse gas emissions. Closed chamber methods are commonly employed for this purpose; however, leaks between the chamber and the atmosphere as well as gas accumulation, known as the concentration buildup effect, can impact flux measurements significantly. In this study, we investigated the impacts of concentration buildup and leaks on semi-rigid closed chamber methods. Field measurements were conducted on six tree species, including three species from a Mexican mangrove ecosystem and three species from a Magellanic sub-Antarctic forest. Systematic observations revealed significant leak flow rates, ranging from 0.00 to 465 L h−1, with a median value of 1.25 ± 75.67 L h−1. We tested the efficacy of using cement to reduce leaks, achieving a leak flow rate reduction of 46–98 % without complete elimination. Our study also demonstrates a clear and substantial impact of concentration buildup on CH4 flux measurements, while CO2 flux measurements were relatively less affected across all tree species studied. Our results show that the combined effects of leaks and concentration buildup can lead to an underestimation of CH4 emissions by an average of 40 ± 20 % and CO2 emissions by 22 ± 22 %, depending on the bark roughness. Based on these findings, we recall a straightforward yet effective method to minimize experimental errors associated with these phenomena, previously established, and reiterated in the current context, for calculating emissions that considers effects of leaks and concentration buildup, while eliminating the need for separate determinations of these phenomena. Overall, the results, combined with a literature review, suggest that our current estimates of GHG flux from tree stems are currently underestimated.

Quantifying evapotranspiration fluxes on green roofs: A comparative analysis of observational methods

Evapotranspiration (ET) is an important process in green stormwater infrastructure (GSI) aiming to reduce urban drainage, to promote cooling and/or to contribute to an urban hydrological balance restoration closer to the natural one. However, on these structures and particularly on green roofs (GR), its evaluation remains challenging and subject to discussion. Estimates of ET by water balance, energy balance, and an ET chamber were performed on five different plots of a full-scale experimental green roof in Trappes (France). Compared to both water balance (90th percentile range of daily ET values: 0.8 mm/d to 3 mm/d) and chamber methods (90th percentile range of daily ET values: 1 mm/d to 1.5 mm/d), the energy balance (90th percentile range of daily ET values is between 1.8 mm and 3.7 mm) produces higher values, 1 to 2 times higher in cumulative values during common periods. The chamber ET displays a similar trend to the energy balance on an hourly basis, and its values remain within the same range as the water balance evaluations on a daily time-step. All three assessments consistently fell below the potential ET values estimated with the Penman-Monteith formula. Critical issues in ET estimation through experimentation have arisen. Sensible heat flux (H) significantly increases ET values when using the energy balance approach compared to the other two methods. The Water Balance method is practical, but on days following rainfall events, the Chamber method may prove more reliable, albeit more time and labour-intensive. The three methods indicated that the substrate thickness was the main contributing factor to increase ET, with well-maintained herbaceous plants providing higher ET values than sedums in thick (15 cm) substrates. In addition, the substrate's nature, especially its organic content, is another factor that promotes ET in green roofs.

Nitrogen fertilization and irrigation types do not affect the overall N2O production potential of a sandy soil, but the microbial community structure and the quantity of functional genes related to the N cycle

Nitrous oxide (N2O), one of the major greenhouse gases, features a 273-fold higher global warming potential compared to carbon dioxide (CO2). Soil-born N2O emissions are based on microbial processes, while the microbial processes are affected by environmental factors and agronomic management measures. The objective of this study was the exploration of the effects of different irrigation and nitrogen (N) fertilization regimes on N2O emissions in relation to the microbial community structure and the quantities of genes involved in the N cycle. The following four treatments were investigated in a sandy soil during the potato cropping season in 2019 in Brandenburg, Germany: drip irrigation without N fertilization (DI-ZN), drip irrigation with broadcasted N fertilization (DI-N), simultaneous application of dissolved N in irrigation water, the so-called fertigation (F), and fertigation without crops (F-ZC). N2O fluxes were measured with the closed chamber method. Microbial biomass was analyzed using phospholipid fatty acids (PLFAs). The bacterial functional genes amoA (ammonium monooxygenase), nxrB (nitrite oxidoreductase), narG (nitrate reductase), nirS/nirK (nitrite reductase), and nosZ (N2O reductase) were determined using quantitative real-time polymerase chain reaction (qPCR). N2O fluxes varied over the season and could mainly be explained by temperature changes. The fertilized treatments showed slightly higher area-related cumulative N2O emissions (DI-ZN: 1.13 kg N2O-N ha−1, DI-N: 1.28 N2O-N ha−1, F: 1.26 N2O-N ha−1, median values). Additionally, N2O flux rates as well as the area- and yield-related N2O emissions of DI-N and F were approximately at the same level, even though the quantities and correlation patterns of the investigated functional genes differed. Highest seasonal median flux rates were detected under DI-N (15.0–100.1 μg N2O-N m−2 h−1), where a greater influence of a nirS/nosZ harboring microbial community was found. In contrast, under F more diverse correlation patterns were found, especially regarding a predominance of nirK and nirS/nosZ harboring microbial community. F-ZC showed the lowest N2O flux rates (−8.7–44.2 μg N2O-N m−2 h−1), which might be explained by the lack of plant carbon sources, particularly root exudates. To conclude, the applied treatments affected the microbial community structure and their genetically determined potential for N2O production, whereby the overall N2O flux rates and hence N2O emissions remained unaffected. Although fertigation is considered to be more demand-based particularly in terms of N fertilization, this study indicates that agronomic management measures according to good faming practice might feature an oversupply of N, neglecting the real N demand of cultivated crops and hence hindering the mitigation of N2O emissions.

Methane Emissions from Rice Fields of the Rostov Region

On the example of the Rostov region, the results of measurements by the chamber method of methane fluxes into the atmosphere from rice fields are analyzed. In addition to measuring methane fluxes in the phases of “germination” and “full ripeness” of rice, concentrations of methane and hydrogen sulfide, Eh, pH, density and humidity were determined in the water of the rice check and various horizons of watered soils. The rate of methane flow into the atmosphere from the surface of the rice check varied in the range from 0.195 to 0.531 mg СН4/(m2 h) and in the “full ripeness” phase of rice was on average 2.1 times higher than in the “germination” phase. The rate of methane flow into the atmosphere from the surface of soils located between rice checks was on average 4.9–12.1 times lower than the rate of its flow from rice checks, varying within 0.034–0.045 mg СН4/(m2 h). It is shown that after watering rice checks in soils isolated by a layer of water, Eh values decrease and, as a consequence, there is an increase in methane concentrations in soils and its fluxes into the atmosphere. According to the assessment, the total methane emission by rice fields of the Rostov region approximately reaches 1.253 tons per day or 150 tons/year, which is 0.4–1.5% of the annual methane release by the soils of the Rostov region.

Bioassay Method Development to Test Sitophilus oryzae Sensitivity against Phosphine

Sitophilus oryzae is a cereal product pest found in warehouses. The presence of this pest negatively impacts the quality and quantity of stored rice. The common method used to control warehouse pests is fumigation. However, frequent use of insecticides will trigger resistance within target pest populations. This study aimed to develop a bioassay method based on the Food Agriculture Organization (FAO) protocols and modify bioassay protocols to determine S. oryzae susceptibility of populations collected from traditional markets across Yogyakarta. Field populations were collected from eight traditional markets in Yogyakarta (Lempuyangan Market [Kapanewon Danurejan], Kranggan Market [Kapanewon Jetis], Caturtunggal Market [Kapanewon Depok], Godean Market [Kapanewon Godean], Imogiri Market [Kapanewon Imogiri], Pleret Market [Kapanewon Pleret], Kasihan Market [Kapanewon Lendah], and Brosot Market [Kapanewon Galur]). The reference population was obtained from the Southeast Asian Regional Centre for Tropical Biology(SEAMEO BIOTROP). The bioassay was carried out following FAO protocols by using a glass jar fumigation chamber (volume 2 L) which was a modification of the desiccator of FAO recommended method number 16. This test used the lowest testable dose for this method: 0.01 × 10-2 mg/2L or 0.5 × 10-2 µg/L tested on 100 imagoes which were divided into five replications and obtained 100% mortality on the second day (48 hours). Results showed that the FAO fumigation chamber method could not be used in the test, so modifications were carried out to determine tested doses by changing the volume of the fumigation container. The test used three container volumes, including 20, 60, and 80 L. Result from 20 L container showed 82-100% mortality, 60 L containers showed 69-100% mortality, and 80 L containers showed 24-79% mortality. Results from 80 L container was suitable for the bioassay because it was able to test the lowest dose on reference insects. Eight doses ranging from 0.125 to 1.625 × 10-2 µg/L, and an untreated control were used to determine the LD50 of phosphine on each population. Insects were fumigated for 48 hours and then removed to observe mortality. The LD50 of the reference population was 0.27 × 10-2 µg/L while 0.29-0.54 × 10-2 µg/L for field populations. These findings indicate that S. oryzae populations collected from traditional markets in Yogyakarta were still susceptible to phosphine.

MiR-128-3p promotes the progression of deep venous thrombosis through binding SIRT1.

This research aimed to study the effect of microRNA-128-3p (miR-128-3p) on deep venous thrombosis (DVT). The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, Transwell chamber method, and flow cytometry technique were used in the cell experiments. Potential interconnection between miR-128-3p and silent information regulator sirtuin 1 (SIRT1) was revealed by luciferase activity. The concentration of miR-128-3p and mRNA SIRT1 was assessed by quantitative reverse transcription polymerase chain reaction (qRT-PCR). The receiver operating characteristic (ROC) curve was used to test the predictive effect of miR-128-3p in DVT. Decreased miR-128-3p expression was beneficial to cell proliferation and migration and inhibited inflammation, apoptosis, and adhesion of human umbilical vein endothelial cells (HUVECs). The impacts of miR-128-3p on HUVECs were achieved by targeting SIRT1. MiR-128-3p was upregulated in patients with DVT, and it was of great significance in differentiating patients with DVT. Overexpression of miR-128-3p might become a biomarker for patients with DVT.

Экологическая оценка пространственной неоднородности и временной изменчивости почвенных потоков СО2 в экосистемах различного типа (на примере Курской области)

The article presents data on the rate of carbon dioxide fluxes from the soil surface of forest, meadow communities and agroecosystems of the Kursk region. The rate of CO2 soil fluxes was estimated using the chamber method. It was established that in June CO2 emission from the soil surface of forest ecosystems varied from 10.2 to 41.7 g CO2 m-2 day-1, from the soil surface of agroecosystems – from 8.2 to 10.6 g CO2 m-2 day-1, and from the soils of meadow ecosystems it reached 37.7 g CO2 m-2 day-1. It was revealed that the rate of soil CO2 fluxes in oak forests was higher than in the community of Robinia pseudoacacia L. and birch forest by 25.6% and 14.9%, respectively. Keywords: CO2 EMISSION, PINE FOREST, BEREZNYAK, OAK, ROBINIA PSEUDOACACIA L., PURE STEAM

Gas storage of peat in autumn and early winter in permafrost peatland

The carbon (C) balance of permafrost peatlands in autumn and winter, which affects the annual C budget estimation, has become a hotspot of studies on peatlands C cycle. This study combined the static chamber method, in situ soil profile measurements, and incubation experiments to investigate release and storage of C during autumn and early winter in a permafrost peatland in the Da Xing'an Mountains, Northeast China. Our results showed that the peak values of CH4 fluxes (30 August 2016) lagged behind those of CO2 fluxes (24 July 2016). At the onset of soil freezing, CH4 fluxes slightly increased, while CO2 fluxes decreased. During soil freezing in autumn, gases were found to be mainly stored in the soil as dissolved CH4 and CO2 and dissolved C concentrations (CH4, CO2, and DOC (dissolved organic carbon)) increased with depth. DOC concentrations were closely related to dissolved C gases, implying that the stored dissolved C gases might be derived from DOC decomposition. The CO2: CH4 ratio decreased sharply from the freezing of the surface layer to the total freezing of the soil, indicating larger CH4 storage in totally frozen soil. The incubation experiments also showed larger CH4 storage in the frozen soils and the stored C gases could influence the assessment of C emissions during thawing. These findings have important implications for clarifying the gas storage of permafrost peatland in autumn and early winter. The results may also clarify the key link of C emissions between the growing season and the nongrowing season.

CH4 emissions from a double-cropping rice field in subtropical China over seven years

Rice paddies are important sources of the greenhouse gas methane (CH4). However, it is difficult to precisely quantify CH4 emissions using the static chamber method because of their discontinuous measurements as well as the spatial and temporal variability of CH4 emissions. To precisely quantify CH4 emissions from rice paddies and gain deep insight into the emission rhythm and environmental effects, a seven-yearlong CH4 flux measurement was carried out continuously using the eddy covariance method in a double cropping rice paddy in subtropical China. The annual CH4 emissions were 42 ± 2 g C m−2. The half hourly CH4 flux was highly correlated with gross primary production (GPP) and environmental factors, such as soil temperature (Ts), and latent heat flux (LE), which explain 47–91% of the CH4 diurnal variation. However, the peak of CH4 generally appeared at dusk during the vigorous growth period, which was quite different from the GPP peak around noon. CH4 flux seasonal dynamic were more complex, with double peaks during the growing season and lower values during the fallow season. Interestingly, in contrast to previous studies of linear or exponential relationships with short-term datasets, daily CH4 and GPP showed a logarithmic relationship at the vegetative stage in this study with seven-year data, this is crucial in improving the model accuracy in estimating annual CH4 emissions. The result implies that long-term observation is necessary to accurately assess CH4 emissions from rice paddy.

CH4 and N2O Emissions of Undrained and Drained Nutrient-Rich Organic Forest Soil

The ability to accurately assess the impact of organic soil drainage on greenhouse gas emissions (GHG) is still limited. Methane (CH4) emissions are characterized by significant variations, and GHG emissions from nutrient-rich organic soil in the region have not been extensively studied. The aim of this study was to assess CH4 and nitrous oxide (N2O) emissions from nutrient-rich organic soil in hemiboreal forests to provide insights into their role in regional GHG balance. Over the course of one year, CH4 and N2O emissions, as well as their affecting factors, were monitored in 31 forest compartments in Latvia in both drained and undrained nutrient-rich organic soils. The sites were selected to include forests of different ages, dominated by silver birch (Betula pendula Roth), Norway spruce (Picea abies (L.) Karsten), and black alder (Alnus glutinosai (L.) Gärtner), as well as clearcuts. Soil GHG emissions were estimated by collecting gas samples using the closed manual chamber method and analyzing these samples with a gas chromatograph. In addition, soil temperature and groundwater level (GW) measurements were conducted during gas sample collection. The mean annual CH4 emissions from drained and undrained soil were −4.6 ± 1.3 and 134.1 ± 134.7 kg CH4 ha−1 year−1, respectively. N2O emissions from undrained soil (4.1 ± 1.4 kg N2O ha−1 year−1) were significantly higher compared to those from drained soil (1.7 ± 0.6 kg N2O ha−1 year−1). In most of the study sites, undrained soil acted as a CH4 sink, with the soil estimated as a mean source of CH4, which was determined by one site where an emission hotspot was evident. The undrained soil acted as a CH4 sink due to the characteristics of GW level fluctuations, during which the vegetation season GW level was below 20 cm.

Controlled-release testing of the static chamber methodology for direct measurements of methane emissions

Abstract. Direct measurements of methane emissions at the component level provide the level of detail necessary for the development of actionable mitigation strategies. As such, there is a need to understand the magnitude of component-level methane emission sources and to test methane quantification methods that can capture methane emissions at the component level used in national inventories. The static chamber method is a direct measurement technique that has been applied to measure large and complex methane sources, such as oil and gas infrastructure. In this work, we compile methane emission factors from the Intergovernmental Panel on Climate Change (IPCC) Emission Factor Database in order to understand the magnitude of component-level methane flow rates, review the tested flow rates and measurement techniques from 40 controlled-release experiments, and perform 64 controlled-release tests of the static chamber methodology with mass flow rates of 1.02, 10.2, 102, and 512 g h−1 of methane. We vary the leak properties, chamber shapes, chamber sizes, and use of fans to evaluate how these factors affect the accuracy of the static chamber method. We find that 99 % of the component-level methane emission rates from the IPCC Emission Factor Database are below 100 g h−1 and that 77 % of the previously available controlled-release experiments did not test for methane mass flow rates below 100 g h−1. We also find that the static chamber method quantified methane flow rates with an overall accuracy of +14/-14 % and that optimal chamber configurations (i.e., chamber shape, volume, and use of fans) can improve accuracy to below ±5 %. We note that smaller chambers (≤20 L) performed better than larger-volume chambers (≥20 L), regardless of the chamber shape or use of fans. However, we found that the use of fans can substantially increase the accuracy of larger chambers, especially at higher methane mass flow rates (≥100 g h−1). Overall, our findings can be used to engineer static chamber systems for future direct measurement campaigns targeting a wide range of sources, including landfills, sewerage utility holes, and oil and natural gas infrastructure.

Measurements and statistical analysis of CO2 efflux and related parameters from crop and forested lands

The LULUCF sector (land use, land use change and forestry) can act as a carbon dioxide (CO2) sink, either by increasing the removal of greenhouse gasses from the atmosphere or by reducing their current emissions. This paper intends to analyze the results of the CO2 monitoring methodology by the chamber method in order to estimate the effect of different land use cover and management techniques. For this purpose, seasonal CO2 efflux field measurements were conducted in two types of ecosystems (forested land and wheat crop) located in the adjacent area of Bucharest. CO2 efflux was analysed for each land cover in relation to the physical characteristics of the soil, respectively soil temperatures and humidity, but also together with the main weather parameters. The measurements were performed simultaneously in both land covers at relevant time intervals. The difference in measured values between the two ecosystems was recorded but the results of the statistical analysis showed a lack of differences in the correlation between the CO2 efflux. This indicates that the CO2 efflux can be affected by particular elements of the environment which facilitates differences in soil temperature and humidity in the same weather conditions.

Phytonematode on Pineapple (Ananas comosus L. Merrill) GP3 Clone With Symptoms of Pineapple mealybug wilt-associated virus (PMWaV)

Pineapple (Ananas comosus L. Merr) is one of Indonesia’s important fruit commodities. Indonesia became the world’s fourth-largest pineapple producer in 2020. The monoculture cultivation system can lead to the continuous presence of pests and diseases in plantation areas. Mealybug wilt disease is caused by Pineapple mealybug wilt-associated virus (PMWaV) and its thought to be associated with phytomatodes. This study aims to determine the type of phytomatodes in pineapple plants with three health degrees: healthy plants, moderate symptoms, and severe symptoms. The soil and roots were sampled at 3, 5, 13, and 14 MAP (Month after Planting). Nematodes were extracted from the soil using the flotation-centrifugation method, while the root samples were extracted using the mist chamber method. Identification of nematode morphology was based on anterior (mouth and stylet shape), posterior (tail shape and reproductive organs), and the type of annulation or nematode cuticle surface. Seven genera of phytomatodes were identified from soil and root samples: Pratylenchus spp., Rotylenchulus spp., Meloidogyne spp., Helicotylenchus spp., Crinonemoides spp., Tylenchus spp., and Rotylenchus spp.. The dominant phytonematodes in the soil samples were Rotylenchulus spp. (66.67/100 ml of soil), while Pratylenchus spp. predominated in the roots (58.33/10 g of roots). Based on the three degrees of plant health, the phytonematodes that dominated the soil samples were Rotylenchulus spp. on the health degree of healthy and moderate symptoms, and Meloidogyne spp. dominate the sample at severe symptoms. Pratylenchus spp. dominated the root samples at healthy and severe symptoms, while Rotylenchulus spp. predominate in moderate symptomatic samples.

A dataset of carbon and water flux observed in aquaculture ponds in Quanjiao, Anhui Province from 2016 to 2020

Aquaculture ponds are inland small water bodies subject to human activities. They are not only carbon sources, but important sources of regional water evaporation. Accurate observation of carbon and water fluxes in aquaculture ponds is the basis for quantifying carbon emission and evaporation contribution of inland water. Nanjing University of Information Science and Technology set up an atmospheric environment experiment site to observe the carbon and water flux over aquaculture water bodies in Guandu Village of Quanjiao County, Anhui Province. This dataset includes the CO2 flux data (measured by the multi-channel closed dynamic floating chamber method), CH4 flux data (measured by the eddy covariance method, multi-channel closed dynamic floating chamber method, and inverted funnel method), latent heat and sensible heat fluxes data (measured by the eddy covariance method), as well as key environmental factors data, such as air temperature, water temperature, and radiation. All data were processed by standardized procedures. Moreover, data quality controls were performed. This dataset can provide important data for accurately estimating carbon emission and evaporation contribution in regional and global inland small water bodies.

A dataset of observational key parameters in carbon and water fluxes in a semi-arid steppe, Inner Mongolia (2012 – 2020): based on a long-term manipulative experiment of precipitation pattern

Warming has led to remarkable changes in global precipitation pattern, which will significantly affect vegetation growth and ecosystem function of the semiarid grasslands in Northern China. As a key processe of ecosystem function, carbon and water flux determines the carbon sequestration capability and resource utilization strategies of ecosystems. Therefore, understanding the responses of ecosystem carbon and water fluxes to precipitation pattern changes and their controls will be helpful for the evaluation in the carbon sequestration capacity of grassland ecosystems. However, there is a lack of long-term experiments and observational data on the responses of carbon and water processes to precipitation pattern changes in grassland ecosystems. Based on the long-term precipitation pattern manipulative experiment (including seven precipitation amount and rain event frequency treatments), we collected seasonal dynamics of ecosystem carbon and water fluxes by the static chamber method connecting with infrared gas analyzer during 2012-2020 in Xilin Gol grassland, Inner Mongolia. The dataset consists of two data files, namely the meteorological environmental data file (including annual precipitation, air temperature, soil moisture, and soil temperature) and the carbon and water fluxes data file (including ecosystem gross primary productivity, ecosystem respiration, net ecosystem carbon exchange, evapotranspiration, carbon use efficiency, and water use efficiency). Preliminary data analysis has shown that the drought treatment could significantly reduce the carbon and water fluxes, while water addition treatment had no significant effect on them. All the parameters recovered to the control level in the first year after the treatment cessation. This dataset is expected to provide important data support for the understanding of the responses of carbon and water cycles and their coupling processes to future precipitation regime in grasslands of Northern China.

VOC Emission from Lightweight Wood Fiber Insulation Board

The aim of the presented research work was to determine and analyze emissions of volatile organic compounds (VOCs) from experimental lightweight wood fiber insulation board produced in dry technology. Until now, there have been no rigid insulation materials made of wood fibers produced in such low density and made in dry technology. Among the typical parameters such as thermal conductivity and the mechanical performance of the lightweight board, attention was also paid to their influence on indoor air quality. Therefore, an attempt was made to determine the kind of substances emitting from wood fiber insulation boards produced at defined production parameters as well as the dynamics of emission reduction over time. Additionally, the influence of fire retardants used for protection against lightweight wood fiberboard fires on the emission of VOCs was analyzed. Tests on VOC emissions were carried out using the chamber method according to the applicable ISO 16000 standards. The main components emitting from lightweight insulation fiberboards were acetic acid and aldehydes such as pentanal, hexanal, heptanal, octanal, nonanal, decanal, furfural, and benzaldehyde. The percentage of acetic acid in total volatile organic compounds (TVOCs) was within the limits of 17% to 65%. From the aldehydes group, the most concerning substance was furfural due to a very strict limit value. In the presented research, depending on the variant, the emission of furfural was from 0 up to 10 µg/m3 after 28 days of measurement. Other substances such as terpenes or aromatic hydrocarbons were at a very low level. The reduction in VOCs over a period of 28 days was significant in most cases from 22% up to 61%. The tests carried out also showed a substantial impact of fire retardant, used in the production of lightweight insulation fiberboard, on the emission of VOCs from fiberboards, and thus on their quality.

The effect of spill change on reliable absolute dosimetry in a synchrotron proton spot scanning system.

Absolute dosimetry measurement is an integral part of Treatment Planning System (TPS) commissioning and it involves measuring the integrated absorbed dose to water for all energies in a pencil beam scanning delivery system. During the commissioning of Singapore's first proton therapy center, a uniform scanned field with an Advanced Markus chamber method was employed for this measurement, and a large dose fluctuation of at least 5% was observed for 10% of the energy layers during repeated measurements. This study aims to understand the root cause of this fluctuation by relating the actual delivered spot information in the log file with the charge measurement by the ion chambers. A dedicated pencil beam dose algorithm was developed, taking into account the log file parameters, to calculate the dose for a single energy layer in a homogeneous water phantom. Three energies, 70.2, 182.7, and 228.7 MeV were used in this study, with the 182.7 MeV energy exhibiting large dose fluctuation. The dose fluctuation was investigated as a function of detector's sizes (pinpoint 3D, Advanced Markus, PTW 34070, and PTW 34089) and water depth (2, 6, and 20cm). Twelve ion chambers measurements were performed for each chamber and depth. The comparison of the theoretically predicted integrated dose and the charge measurement served as a validation of the algorithm. About 5.9% and 9.6% dose fluctuation were observed in Advanced Markus and pinpoint 3D measurements at 2cm depth for 182.7 MeV, while fluctuation of 1.6% and 1.1% were observed in Advanced Markus with 228.7 and 70.2 MeV at similar depth. Fluctuation of less than 0.1% was observed for PTW34070 and PTW 34089 for all energies. The fluctuation was found to diminish with larger spot size at 20cm depth to 1.3% for 182.7 MeV. The theoretical and measured charge comparison showed a high linear correlation of for all datasets, indicating the fluctuation originated from the delivered spot characteristics. The cause of fluctuation was identified to be due to the spill change occurring close to the detector, and since the spot positional deviation profiles were different between two spills, this resulted in local hot spots between columns of spots. The actual position of spill change varies randomly during measurement, which led to a random occurrence of hot spot within the detector's sensitive volume and a fluctuating dose measurement. This is the first report of a dose fluctuation greater than 5% in absolute dosimetry measurement with a uniform scanned field and the cause of the fluctuation has been conclusively determined. It is important to choose the MU and scanning pattern carefully to avoid spill change happening when the spot delivery is near the detector.

Design and simulation of a cylindrical μRWELL inner tracker for the experiment at the Super Tau-Charm Facility

The Super Tau-Charm Facility (STCF) is a future electron-positron collider operating in a center-of-mass energy range from 2 to 7 GeV with a peak luminosity of 0.5 × 1035 cm-2s-1. A high-performance detector is required for the STCF experiment to meet the STCF physics goals. A low-material cylindrical inner tracker based on the micro-resistive well detector (μRWELL) is proposed for the STCF experiment. In this paper, the design of the μRWELL inner tracker is presented. A good balance between material budget, structural strength, and detector performance is achieved in the design where the material budget of the μRWELL inner tracker is estimated to be 0.29% X/X0, a 40% reduction w.r.t. that of the cylindrical gas electron multiplier (CGEM) detector used at the KLOE experiment. The hit position of the detector is reconstructed using an algorithm combing the micro-time projection chamber (μ-TPC) method and the charge center-of-gravity method. The detector performance was studied in detail using simulation with Garfield and Geant4. With the optimum working gas of Ar: CO2 = 85:15, this detector can obtain a spatial resolution better than 100 μm and 400 μm in 1 T magnetic field in rφ and beamline direction, respectively. The simulated momentum resolution and vertex resolution of the whole STCF tracking system including the μRWELL inner tracker and a large drift chamber can meet the requirements for the STCF detector, benefiting from the optimized inner tracker design.

Permafrost Effect on the Spatial Distribution of CO2 Emission in the North of Western Siberia (Russia)

The landscapes in the discontinuous permafrost area of Western Siberia are unique objects for assessing the direct and indirect impact of permafrost on greenhouse gas fluxes. The aim of this study was to identify the influence of permafrost on the CO2 emission at the landscape and local levels. The CO2 emission from the soil surface with the removed vegetation cover was measured by the closed chamber method, with simultaneous measurements of topsoil temperature and moisture and thawing depth in forest, palsa, and bog ecosystems in August 2022. The CO2 emissions from the soils of the forest ecosystems averaged 485 mg CO2 m−2 h−1 and was 3–3.5 times higher than those from the peat soils of the palsa mound and adjacent bog (on average, 150 mg CO2 m−2 h−1). The high CO2 emission in the forest was due to the mild soil temperature regime, high root biomass, and good water–air permeability of soils in the absence of permafrost. A considerable warming of bog soils, and the redistribution of CO2 between the elevated palsa and the bog depression with water flows above the permafrost table, equalized the values of CO2 emissions from the palsa and bog soils. Soil moisture was a significant factor of the spatial variability in the CO2 emission at all levels. The temperature affected the CO2 emission only at the sites with a shallow thawing depth.

Temperature response of ammonia emission from sandy loam soil amended with manure compost and urea

Ammonia (NH3) emission is an atmospheric pollutant that harms the environment and public health. Although the use of nitrogen (N) - based fertilizer to increase crop output is a significant source of NH3 emissions, it is unclear what factors speed up this process. A laboratory incubation study using the dynamic chamber method was performed to evaluate the impact of manure compost and N rates on NH3 emission at different temperatures (15, 25, and 35 °C). The ammonia emission from sandy loam soil treated with compost at 110 kg N ha−1 (CU0) and urea at 100, 200, and 400 kg N ha−1: CU1, CU2, and CU3, respectively, were monitored for 28 days. The result showed that cumulative NH3 emission increased with temperature and N application rates. At the three temperature regimes, N loss via NH3 emission ranged between 7.2 and 8.3, 8.04 and 12.78, and 13.79 and 44.78 percent of N applied to CU1, CU2, and CU3, respectively. The activation energy was highest in CU3 treatments in all the temperature regimes resulting in 36%–60% higher compared to others. The temperature quotient (Q10) of NH3 emission ranged between 0.28 and 8.06 and 0.18 and 14.91 at 15–25 °C and 25–35 °C, respectively. This study demonstrated that the application of compost (110 kg N ha−1) and urea (100 or 200 kg N ha−1) at low temperatures (< 25 °C) is a good strategy to reduce ammonia volatilization, improve N use efficiency and soil properties.