Carbon dioxide and methane emissions from Tanswei River in Northern Taiwan

Municipal solid waste (MSW) landfills are among the major sources of greenhouse gas (GHG) emissions affecting global warming and the Earth’s climate. In Bulgaria, 53 regional non-hazardous waste landfills (RNHWL) are in operation, which necessitates conducting studies to determine the environmental risk from the emitted GHGs. This study attempted to assess the CH4 and CO2 emissions from three gas wells of a cell (in active and closed phases, each of 2.5 years duration) in an RNHWL, Harmanli (41°54′24.29″ N; 25°53′45.17″ E), based on monthly in situ measurements by portable equipment, using the Interrupted Time Series (ITS) ARMA model. The obtained results showed a significant variation of the CH4 and CO2 concentrations (2.06–15.1% v/v) and of the CH4 and CO2 emission rates (172.81–1762.76 kg/y) by gas wells (GWs), months and years, indicating the dynamics of the biodegradation of the deposited waste in the areas of the three GWs. Throughout most of the monitoring period (2018–2022), the CH4 concentrations were higher than the CO2 concentrations (% v/v), while CO2 emissions were lower than CH4 emissions (kg/y), a fact that could be explained by the differences in the mass of the two gases. The emissions rates of both gases from GW2 dominated over those from GW1 and GW3, giving a reason to determine the zone of GW2 as a hotspot of Cell-1. On the whole, CH4 and CO2 emission rates were higher in the winter (December–February) and partly in the spring (March–May) compared to summer–autumn (June–November). However, the CH4 and CO2 concentrations and emissions decreased drastically after the Cell-1 closure. The CH4/CO2 ratio (0.68–2.01) by months and gas wells demonstrated a great sensitivity, making it a suitable indicator for the assessment of organic waste biodegradation level in the landfills. The ITS ARMA model confirmed the negative and significant effect of the cell closure on CH4 and CO2 emissions; the correlations found between predicted and observed values were strong and positive (0.739–0.896).

BackgroundSoil-derived prokaryotic gut communities of the Japanese beetle Popillia japonica Newman (JB) larval gut include heterotrophic, ammonia-oxidizing, and methanogenic microbes potentially capable of promoting greenhouse gas (GHG) emissions. However, no research has directly explored GHG emissions or the eukaryotic microbiota associated with the larval gut of this invasive species. In particular, fungi are frequently associated with the insect gut where they produce digestive enzymes and aid in nutrient acquisition. Using a series of laboratory and field experiments, this study aimed to (1) assess the impact of JB larvae on soil GHG emissions; (2) characterize gut mycobiota associated with these larvae; and (3) examine how soil biological and physicochemical characteristics influence variation in both GHG emissions and the composition of larval gut mycobiota.MethodsManipulative laboratory experiments consisted of microcosms containing increasing densities of JB larvae alone or in clean (uninfested) soil. Field experiments included 10 locations across Indiana and Wisconsin where gas samples from soils, as well as JB and their associated soil were collected to analyze soil GHG emissions, and mycobiota (ITS survey), respectively.ResultsIn laboratory trials, emission rates of CO2, CH4, and N2O from infested soil were ≥ 6.3× higher per larva than emissions from JB larvae alone whereas CO2 emission rates from soils previously infested by JB larvae were 1.3× higher than emissions from JB larvae alone. In the field, JB larval density was a significant predictor of CO2 emissions from infested soils, and both CO2 and CH4 emissions were higher in previously infested soils. We found that geographic location had the greatest influence on variation in larval gut mycobiota, although the effects of compartment (i.e., soil, midgut and hindgut) were also significant. There was substantial overlap in the composition and prevalence of the core fungal mycobiota across compartments with prominent fungal taxa being associated with cellulose degradation and prokaryotic methane production/consumption. Soil physicochemical characteristics such as organic matter, cation exchange capacity, sand, and water holding capacity, were also correlated with both soil GHG emission, and fungal a-diversity within the JB larval gut. Conclusions: Results indicate JB larvae promote GHG emissions from the soil directly through metabolic activities, and indirectly by creating soil conditions that favor GHG-associated microbial activity. Fungal communities associated with the JB larval gut are primarily influenced by adaptation to local soils, with many prominent members of that consortium potentially contributing to C and N transformations capable of influencing GHG emissions from infested soil.

Deadwood is an important component of the global carbon cycle, and its decomposition releases carbon dioxide (CO2) and methane (CH4) into the atmosphere. However, the main drivers of these greenhouse gas emissions from deadwood are not well understood. We investigated drivers that govern the CO2 and CH4 emission rates of 793 deadwood specimens from 13 different tree species, which were exposed on 27 forest and 38 grassland plots at Schorfheide‐Chorin (Germany) for one year. Tree species identity was an important driver for emissions of both gases, whereas habitat type and management intensity were only important for CO2 emission rate. CO2 emission rates were positively linked to mass loss and were one‐third higher in forest compared to grassland habitats. The wood traits organic extractives, lignin, and sulfur content were negatively associated with CO2 emission rates, whereas carbon, nitrogen, and magnesium content showed the opposite effect. Among climate variables, air humidity in forest and soil moisture in grassland habitats positively affected CO2 emission rates. CH4 emission rates showed a negative relationship with increasing wood density exposed in both habitat types but were positively related to tree species with higher sulfur contents. Taken together, CO2 emission rates from deadwood were well predicted by wood traits, management intensity and climatic variables, whereas CH4 emission rates were less well predictable and were influenced only by wood traits that differed from those of CO2 emissions. Our results provide a deeper insight into the mineralization processes of deadwood and should be considered in further carbon cycle assessments.

Palm oil mill effluent (POME) treatment in Indonesia is still predominant using an open pond system. This system has the weakness of the unknown and uncontrollable value of greenhouse gas (GHG) emissions into the atmosphere. This study estimated GHG emissions (CH4 and CO2) from anaerobic ponds and their potential as a renewable energy source and obtain GHG emission conversion coefficients for each kg of COD POME and ton of crude palm oil (CPO). Gas samples were collected using a closed static chamber. GHG sample concentration testing was done using Gas Chromatography with a flame ionization detector (FID) and thermal conductivity detector (TCD). The results showed that the emission rate of CH4 and CO2 in the anaerobic pond POME treatment was relatively high, 261.93 and 595.99 g/m2/day, respectively, equivalent to 48.572 t CO2-eq/day or 14,571.5 t CO2-eq/year. CO2 emissions were greater than two times CH4 emissions, both spatially and temporally. There was a process of facultative biodegradation, aerobic and or anaerobic process according to the biotic-abiotic environment and the levels of organic components in the substrate. In anaerobic ponds, the optimal requirements for the biodegradation process tended to be unfulfilled, so the emission rate of CH4 was less than CO2. The GHG conversion coefficient was obtained, namely each kg of COD from POME emitted 6.266 kg CO2-eq of GHG; for each m3 of POME emitted by 0.163 t CO2-eq of GHG; and 0.556 t CO2-eq/t CPO. The maximum potential for POME to energy conversion was 1.045 MWe with a power capacity of 8,603 MWh/year.

Emissions of ammonia, nitrous oxide, methane, and carbon dioxide during storage of dairy cow manure as affected by dietary forage-to-concentrate ratio and crust formation

Emissions of CH4, CO2, and N2O from conventional septic tank systems are known to occur, but there is a dearth of information as to the extent. Mass emission rates of CH4, CO2, and N2O, as measured with a modified flux chamber approach in eight septic tank systems, were determined to be 11, 33.3, and 0.005 g capita(-1) day(-1), respectively, in this research. Existing greenhouse gas (GHG) emission models based on BOD (biochemical oxygen demand) loading have estimated methane emissions to be as high as 27.1 g CH4 capita(-1) day(-1), more than twice the value measured in our study, and concluded that septic tanks are potentially significant sources of GHGs due to the large number of systems currently in use. Based on the measured CH4 emission value, a revised CH4 conversion factor of 0.22 (compared to 0.5) for use in the emissions models is suggested. Emission rates of CH4, CO2, and N2O were also determined from measurements of gas concentrations and flow rates in the septic vent system and were found to be 10.7, 335, and 0.2 g capita(-1)day(-1), respectively. The excellent agreement in the CH4 emission rates between the flux chamber and the vent values indicates the dominant CH4 source is the septic tank.

This paper evaluates the relationship between ultraviolet‐B (UV‐B, 280–315 nm) radiation enhancement on the earth's surface caused by ozone attenuation and climate change. A pot experiment was conducted to investigate the effects of enhanced UV‐B radiation on greenhouse gas (GHG) emissions from the paddy soil with rice straw incorporation (SI). The paddy soil was sampled from the Yuanyang Terrace, Yunnan Province, Southwest China. There were four treatments: natural light (control check, CK), 5.0 kJ·m−2 UV‐B radiation (UVB), SI, and SI + UVB. The effects of UV‐B radiation (5.0 kJ·m−2) on straw degradation, soil carbon invertase activity, active organic carbon content, and GHG emissions were studied. The results showed that UV‐B radiation promoted the degradation of straw components (lignin, cellulose, hemicellulose, and water‐soluble phenol). The SI treatment significantly increased the activity of soil carbon invertase (P < 0.05), the content of soil active organic carbon (P < 0.05), and the emission rates and amounts of GHGs (P < 0.05). Compared to the SI treatment, SI + UVB treatment reduced soil carbon invertase activity and active organic carbon content, resulting in a 17% reduction in CH4 emission and a 40% and 16% increase in CO2 and N2O emission (P < 0.05), but had no significant effect on the global warming potential (GWP). Correlation analysis showed that the degradation rate of straw components was positively correlated with the activity of carbon invertase, the contents of microbial biomass carbon (MBC), easily oxidized organic carbon (EOC), and the CO2 emission rate; the activities of sucrase and cellulase were positively correlated with the contents of MBC and EOC, which were in turn positively correlated with the emission rates of CH4 and CO2. Under SI, UV‐B radiation reduced the soil carbon conversion, which led to a decreased CH4 emission and increased emissions of CO2 and N2O, but did not alter the GWP of GHGs from the paddy soil. © 2020 Society of Chemical Industry and John Wiley & Sons, Ltd.

There are large areas of spontaneous coal combustion in northern and northwestern China. The quantification of greenhouse gas (GHG) emissions resulting from spontaneous coal combustion is an important step toward determining proper management practices to reduce such emissions in the future. The present study investigated the GHG emission characteristics of the spontaneous combustion of 10 typical coal types. Furthermore, this study examined the estimation method applied to the GHG emissions caused by spontaneous coal combustion. The experimental results showed that the rates of CH4 and CO2 emissions from spontaneous coal combustion resulting from mining activities were greater than the same rates of emissions resulting from mere surface air seepage (by factors of ∼1.8 and ∼1.6, respectively). The emission rate of CH4 was significantly correlated with the volatile content of coal, while the emission rate of CO2 was significantly correlated with the moisture, oxygen, and sulfur contents of coal. Three diff...

Wetland stores substantial amount of carbon and may contribute greatly to global climate change debate. However, few researches have focused on the effects of global climate change on carbon mineralization in Zoige al- pine wetland, Qinghai-Tibet Plateau, which is one of the most important peatlands in China. Through incubation ex- periment, this paper studied the effects of temperature, soil moisture, soil type (marsh soil and peat soil) and their in- teractions on CO2 and CH4 emission rates in Zoige alpine wetland. Results show that when the temperature rises from 5℃ to 35℃, CO2 emission rates increase by 3.3-3.7 times and 2.4-2.6 times under non-inundation treatment, and by 2.2-2.3 times and 4.1-4.3 times under inundation treatment in marsh soil and peat soil, respectively. Compared with non-inundation treatment, CO2 emission rates decrease by 6%-44%, 20%-60% in marsh soil and peat soil, respec- tively, under inundation treatment. CO2 emission rate is significantly affected by the combined effects of the tempera- ture and soil type (p < 0.001), and soil moisture and soil type (p < 0.001), and CH4 emission rate was significantly af- fected by the interaction of the temperature and soil moisture (p < 0.001). Q10 values for CO2 emission rate are higher at the range of 5℃-25℃ than 25℃-35 , ℃ indicating that carbon mineralization is more sensitive at low temperature in

Comprehensive analysis of greenhouse gases emissions and microbial dynamics in glacier-fed lakes across various ablation stages.

Prescribed fires or wildfires are common in natural ecosystems. Biochar input during fires can impact soil greenhouse gas (GHG) emissions, including methane (CH4), carbon dioxide (CO2), and nitrous oxide (N2O). Meadows are functionally important ecosystems due to their large carbon (C) and nitrogen (N) stocks and potential to mitigate GHG emissions. The effects of biochar on meadow GHG emissions may be sensitive to whether it is derived from more than one type of vegetation, especially with N addition and warming. To further our understanding of how input of fire-derived biochar affects meadow soil GHG emissions, especially under the context of N deposition and warming, we conducted this study to examine potential non-additive effects of these factors. We collected soils from meadows dominated by Miscanthus sinensis and Arundinella hirta at Wugong Mountain (Jiangxi, China). Biochar was produced by pyrolyzing the aboveground vegetation of each of the two species at 450 °C for 1 h. Mixed biochar was produced by 1:1 ratio. Soil GHG emissions and N transformations were measured by incubating soils with biochar (control, M. sinensis biochar, A. hirta biochar, mixed biochar) and N addition (control vs. 6 g m−2) treatments at different temperatures (10, 15, 20, or 25 °C). Biochar input consistently increased both CH4 and N2O flux, but only A. hirta and mixed biochar decreased CO2 emission rates. Mixed biochar imposed non-additive effects on cumulative CH4 and CO2 emissions. Biochar decreased soil nitrification rates and increased the temperature sensitivity of soil N2O emission rates. The results indicated that biochar input during fires in meadows impacts soil GHG emissions and N transformations. Input of biochar into meadow soil following fire impacted GHG emissions, and mixing biochar derived from different species imposed non-additive effects on CH4 and CO2 emissions. The variable and non-additive biochar effects on soil GHG emissions showed that fire-induced alterations in meadow soil GHG emissions will depend on the species composition of the local plant community. The effects of biochar on meadow soil GHG emissions after fires should be considered in future budgets of meadow soil GHG emissions and prediction of prescribed fire impacts on meadow ecosystems under the context of N deposition and warming.

The influence of incorporating microbial fuel cells on greenhouse gas emissions from constructed wetlands

Biochar produced from plant biomass through pyrolysis has been shown to be much more resistant to biodegradation in the soil as compared with the raw biomass, such as cereal straw that is routinely shredded and discharged on to farm fields in large amounts. Biochar application to soil has also been reported to decrease greenhouse gas (GHG) emissions, although the mechanisms are not fully understood. In this study, the emissions of three main GHGs (CO2, CH4, and N2O) and enzyme activities (urease, β-glycosidase, and dehydrogenase) were measured during a 100-day laboratory incubation of a Chernozemic soil amended with either straw or its biochar at rates of 0.67 and 1.68 % (based on the amount of C added) for the low and high rates, respectively. The biochar application dramatically reduced N2O emissions, but CO2 or CH4 emissions were not different, as compared with the un-amended soil. At the same C equivalent application rate, CO2 and N2O emission rates were greater while CH4 emission rates were lower in straw than in biochar application treatments. The activities of both the dehydrogenase and β-glycosidase significantly declined while that of urease significantly increased with the biochar as compared with the straw treatment. We conclude that pyrolysis of cereal straw prior to land application would significantly reduce CO2 and N2O emissions, in association with changed enzyme activities, while increasing the soil C pool through the addition of stable C in the form of biochar.

To provide a corresponding preparation and foundation for the implementation and testing of China 6, as well as provide a strong reference for the formulation of China automotive test cycle (CATC) in the future, portable emission measurement system (PEMS) was applied to carry out CO and NOx emissions test on conventional roads for a light-duty gasoline vehicle (Toyota Levin) and a heavy-duty diesel vehicle (KING LONG bus) in Nanjing. The results showed that the CO emission rate of the Toyota car was mainly determined by the speed. As the vehicle speed increased, the CO emission rate increased rapidly while it was below 0.035 g/s. The CO emission rate of KING LONG bus accelerated with the increase of the vehicle speed at the lower speed and began to decrease when the speed reached 60 km/h. In terms of NOx emission rate, as the vehicle speed increased, the NOx emission rates of both vehicles increased. The CO and NOx emission factors of the two models showed similar patterns, both of which decreased significantly as the vehicle speed increased. Compared with the corresponding emission limits, the CO emission of both vehicles was higher, especially for light vehicle, and it was more than 3 times the limit. The NOx emission of both vehicles met the corresponding emission standards. The CO and NOx emission rates of light vehicles were positively correlated with specific power of vehicle (VSP). When VSP was less than 16, the two pollutants emission rate variation with VSP of heavy vehicle showed the same trend, while it was different when VSP was more than 16.

This research focused on the nutrient removal and the simultaneous CO2, CH4, and N2O emission rates of various combinations of vertical subsurface flow constructed wetlands (VSFCWs) and earthworm eco-filters (EEs) under different influent C/N ratios in synthetic wastewater. The optimal parameters for nutrient removal were influent C/N ratios of 5 : 1 and 10 : 1 as well as the combination VSFCW-EE. Relatively low values of greenhouse gas (GHG) emission rates measured in situ were obtained at a C/N ratio of 5 : 1. The emission rates of CH4 and N2O were considerably lower than that of CO2. The VSFCW-EE and EE-VSFCW combinations showed similar GHG emission results. The C/N ratio of 5 : 1 and the VSFCW-EE combination exhibited the highest nutrient removal efficiency with the lowest GHG emission rate. Wastewater nutrient removal and GHG emission were both high during summer (June to August) and low during winter (December to February).