Affect Greenhouse Gas Research Articles

Spatial pattern of CO2 and CH4 emission and its influencing factors from river confluence areas

ABSTRACT Rivers emit large amounts of greenhouse gases globally. The confluence area is a crucial component of the carbon cycle in inland waters. However, a comprehensive understanding of the characteristics and control of vertical greenhouse gas exchanges in confluence areas is still lacking. The fluxes of CH4 and CO2 in a typical confluence area in Northwest China (Yellow-Fen River) were measured using a flux-box-greenhouse gas analyzer in February 2023. Additionally, environmental and water quality parameters were measured to determine the changing characteristics and principal drivers of greenhouse gas emissions in the river confluence waters. The results showed that the CO2 and CH4 fluxes in the confluence area ranged from 94.89 to 326.29 and 1.47 to 3.89 mg m−2 h−1, respectively. The greenhouse gas emission intensity at the confluence surpassed that at the other sample points. Further analysis indicated that pH, chemical oxygen demand (COD), v (flow velocity), (dissolved organic carbon) DOC, (dissolved inorganic carbon) DIC and (dissolved total carbon) DTC were the key factors affecting greenhouse gas emissions in these areas. This study is important for understanding the characteristics of CO2 and CH4 fluxes in river confluence areas, and provides useful reference information for future research and prediction models.

Evaluating the effectiveness of environmental taxes: A Case study of carbon pricing in the UK as a tool to reducing Greenhouse Gases Emissions

This paper evaluated the effectiveness of environmental taxes and adopted a case study approach which used carbon pricing in the UK as a tool to reducing Greenhouse Gases Emissions. The objectives of the research are to determine the effect of carbon pricing on greenhouse gases emissions in the United Kingdom, evaluate how fossil energy depletion affect greenhouse gases emissions in the United Kingdom and ascertain the effect of total energy consumption from different energy mix on greenhouse gases emissions in the United Kingdom. The paper used an ex post facto research design and the estimated model was estimated using the ordinary least squares regression technique. The data were sourced from different sources and covered the period between 2010 and 2023. The findings of the study revealed that carbon pricing is an effective tool for reducing greenhouse gases emissions in the UK while renewable energy is also a significant tool for reducing greenhouse gases emissions. Based on these findings, the study recommends that the government should consider increasing the carbon price incrementally over time to ensure that it continues to effectively discourage high-emission activities.

How does temperature affect greenhouse gas emissions from food consumption in restaurants?

The influence of weather and on human behavior and business activities is a recurring theme in marketing literature. This study investigated the mechanisms through which temperature affects food consumption in restaurants and the associated greenhouse gas (GHG) emissions. Drawing on an extensive dataset from a leading restaurant chain in China, we analyzed approximately nine million transactions from January 1, 2018, to December 31, 2021. Our findings highlight a U-shaped correlation between external temperature and GHG emissions resulting from food consumption in restaurants. Interestingly, consumer mood, influenced by temperature, follows an inverted U-shaped trajectory. Delving further, we discovered that deteriorating consumer mood significantly elevated GHG emissions from food consumption in restaurants. Such findings underscore a concerning feedback loop: extreme temperatures exacerbate unhealthy food choices driven by mood disturbances, which in turn amplify GHG emissions—creating a detrimental cycle that benefits neither health nor the environment.

Physicochemically protected organic carbon release is the rate-limiting step of rhizosphere priming in paddy soils

Iron oxides affect the stability of soil organic matter (SOM), which in turn affects greenhouse gas emissions in paddy soils. They also regulate the direction and magnitude of the rhizosphere priming effect (RPE) by restricting SOM accessibility and microbial activity. However, the controlling steps and key factors that regulate the RPE magnitude under anoxic conditions are unknown. In this study, we investigated the mechanisms through which Fe(III) reduction affects the RPE using humic acid as an electron shuttle in paddy soils and conducting continuous 13CO2 labeling of rice plants. The RPE, measured via CO2 emission, was approximately 25 % greater in soils with humic acid than in soils without. A rapid increase in the RPE of CH4 emissions after 41 days was attenuated in soils containing humic acid. Root growth and Fe(III) reduction stimulated the total primed CO2 emissions from the rhizosphere independent of the microbial biomass and enzyme activities. Humic acid accelerated Fe(III) reduction, leading to a decrease in Fe-bound organic carbon and an increase in RPE (CO2 emissions). The rhizosphere-primed CO2 emissions decreased with increasing amounts of reactive Fe(III) (oxyhydr)oxides, which protected the SOM from microbial and enzymatic attacks. Biochemical Fe(III) reduction and physical aggregate destruction controlled the abiotic transformation of inaccessible SOM into bioavailable organic carbon, thereby regulating the RPE. The results suggest that the reduction of reactive Fe(III) minerals is the rate-limiting step in the release of the physicochemically protected SOM, which in turn determines the magnitude of rhizosphere priming in paddy soils.

Combined metabolomic and microbial community analyses reveal that biochar and organic manure alter soil C-N metabolism and greenhouse gas emissions

The use of biochar to reduce the gas emissions from paddy soils is a promising approach. However, the manner in which biochar and soil microbial communities interact to affect CO2, CH4, and N2O emissions is not clearly understood, particularly when compared with other amendments. In this study, high-throughput sequencing, soil metabolomics, and quantitative real-time PCR were utilized to compare the effects of biochar (BC) and organic manure (OM) on soil microbial community structure, metabolomic profiles and functional genes, and ultimately CO2, CH4, and N2O emissions. Results indicated that BC and OM had opposite effects on soil CO2 and N2O emissions, with BC resulting in lower emissions and OM resulting in higher emissions, whereas BC, OM, and their combined amendments increased cumulative CH4 emissions by 19.5 %, 31.6 %, and 49.1 %, respectively. BC amendment increased the abundance of methanogens (Methanobacterium and Methanocella) and denitrifying bacteria (Anaerolinea and Gemmatimonas), resulting in an increase in the abundance of mcrA, amoA, amoB, and nosZ genes and the secretion of a flavonoid (chrysosplenetin), which caused the generation of CH4 and the reduction of N2O to N2, thereby accelerating CH4 emissions while reducing N2O emissions. Simultaneously, OM amendment increased the abundance of the methanogen Caldicoprobacter and denitrifying Acinetobacter, resulting in increased abundance of mcrA, amoA, amoB, nirK, and nirS genes and the catabolism of carbohydrates [maltotriose, D-(+)-melezitose, D-(+)-cellobiose, and maltotetraose], thereby enhancing CH4 and N2O emissions. Moreover, puerarin produced by Bacillus metabolism may contribute to the reduction in CO2 emissions by BC amendment, but increase in CO2 emissions by OM amendment. These findings reveal how BC and OM affect greenhouse gas emissions by modulating soil microbial communities, functional genes, and metabolomic profiles.

Mechanisms of Agricultural Scale Affecting Greenhouse Gas Emissions

Mechanisms of Agricultural Scale Affecting Greenhouse Gas Emissions

To Harvest or not to Harvest: Management Intensity did not Affect Greenhouse Gas Balances of Phalaris Arundinacea Paludiculture

The cultivation of flooding-tolerant grasses on wet or rewetted peatlands is a priority in climate change mitigation, balancing the trade-off between atmospheric decarbonisation and biomass production. However, effects of management intensities on greenhouse gas (GHG) emissions and the global warming potential (GWP) are widely unknown. This study assessed whether intensities of two and five annual harvest occurrences at fertilisation rates of 200 kg nitrogen ha− 1 yr− 1 affects GHG exchange dynamics compared to a ‘nature scenario’ with neither harvest nor fertilisation. Fluxes of carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O), using opaque and transparent chambers, were measured on a wet fen peatland with a mean water table depth of -10 cm below soil surface. Overall, no treatment effect was found on biomass yields and GHG emissions. Annual cumulative CH4 emissions were low, ranging between 0.3 and 0.5 t CO2-C eq ha− 1 yr− 1. Contrary to this, emissions of N2O were high, ranging between 1.1 and 1.5 t CO2-C eq ha− 1 yr− 1. For magnitudes of CH4 and N2O, soil moisture conditions and electrical peat properties were critical proxies. Atmospheric uptake of CO2 by net ecosystem exchange was higher for the treatments with management. However, this benefit was offset by the export of carbon in biomass compared to the treatment without management. In conclusion, the results highlighted a near-equal GWP in the range of 10.5–11.5 t CO2-C eq t ha− 1 yr− 1 for all treatments irrespectively of management. In a climate context, a restoration scenario but also intensive paludiculture practices were equal land-use options.

Technology Oriented Struggle Against Climate Change in Transportation Sector: An Empirical Investigation

The transportation sector is one of the most important sectors in which greenhouse gas emissions (GHG) are the highest, thus causing the global warming problem to rise. One of the most effective and international solutions to this problem is considered to be a technology-oriented struggle, and the development of green technologies is encouraged by global authorities. The study aims to investigate the success of the technology-oriented struggle against global warming in the transport sector. In analyses, data on transportation-related greenhouse gas emissions, the number of patents (transport-related climate change mitigation technologies), trade openness, and GDP per capita of 12 OECD countries years between 1999-2017 were used. To identify the long-run and short-run relationship among variables, the Cross-Sectional Autoregressive Distributed Lags Estimator (CSARDL) and also the Mean Group (MG), Augmented Mean Group (AMG), and Common Correlated Effects Mean Group Estimators (CCE) were applied. According to the estimators' findings, no evidence was found that the number of patents and trade openness affected greenhouse gas emissions, but it was determined that GDP positively affected greenhouse gas emissions. As a result, it can be said that the technology-oriented struggle against climate change in the transportation sector alone isn't sufficient to reduce transportation-related GHG emissions.

A Mixture of Prebiotics, Essential Oil Blends, and Onion Peel Did Not Affect Greenhouse Gas Emissions or Nutrient Degradability, but Altered Volatile Fatty Acids Production in Dairy Cows Using Rumen Simulation Technique (RUSITEC)

A Mixture of Prebiotics, Essential Oil Blends, and Onion Peel Did Not Affect Greenhouse Gas Emissions or Nutrient Degradability, but Altered Volatile Fatty Acids Production in Dairy Cows Using Rumen Simulation Technique (RUSITEC)

Downstream natural gas composition across U.S. and Canada: implications for indoor methane leaks and hazardous air pollutant exposures

Previous research has shown that natural gas (NG) leaks from residential appliances are common, affecting greenhouse gas emission inventories and indoor air quality. To study these implications, we collected and analyzed 587 unburned NG samples from 481 residences over 17 North American cities for hydrocarbons, hazardous air pollutants, and organosulfur odorants. Nearly all (97% of) gas samples contained benzene (between-city mean: 2335 ppbv [95% CI: 2104, 2607]) with substantial variability between cities. Vancouver, Los Angeles, Calgary, and Denver had at least 2x higher mean benzene concentrations than other cities sampled, with Vancouver exhibiting a nearly 50x greater mean benzene level than the lowest-concentration city (Boston). We estimate that current U.S. and Canadian emissions inventories are missing an additional 25 000 [95% CI: 19 000, 34 000] and 4000 [95% CI: 3700, 5200] lbs benzene yr−1 through downstream NG leakage, respectively. Concentrations of odorants added for leak detection varied substantially across cities, indicating a lack of standardization. Houston, for instance, had 5x higher mean tert-butyl mercaptan levels than Toronto. Using these odorant measurements, we found that methane emissions as high as 0.0080–0.28 g h−1 and indoor benzene enhancements 0.0096–0.11 ppbv could go undetected by persons with an average sense of smell, with large uncertainties driven by smelling sensitivity, gas composition, and household conditions. We also observed larger leaks (>10 ppm ambient methane) in ∼4% of surveyed homes, confirming that indoor leakage occurs at varying degrees despite the presence of odorants. Overall, our results illustrate the importance of downstream NG composition to understand potential emissions, exposures, and odor-mediated leak detection levels. Given methane’s global warming potency, benzene’s toxicity, and wide variation in smelling abilities, our findings highlight the deficiencies regarding the sole reliance on odorization to alert and protect all occupants from indoor leaks.

Can the Integration of Water and Fertilizer Promote the Sustainable Development of Rice Production in China?

Rice production is the agricultural activity with the highest energy consumption and carbon emission intensity. Water and fertilizer management constitutes an important part of energy input for rice production and a key factor affecting greenhouse gas emissions from paddy fields. Water–fertilizer integration management (AIM) is an automated water and fertilizer management system for large-scale rice production, which can effectively save water and fertilizer resources. At present, the energy utilization and environmental impact of AIM in rice production are not clear. To clarify whether AIM is a water and fertilizer management measure that combines energy conservation and carbon emission reduction, a comparative study between the widely used farmers’ enhanced water and fertilizer management (FEM) in China and AIM was conducted in this paper. Field experiments were conducted to evaluate the rice yield, carbon emission, energy utilization, and economic benefits of the two management methods. The results showed that AIM reduced water and fertilizer inputs, energy inputs, and economic costs by 12.18–28.57%, compared to FEM. The energy utilization efficiency, energy profitability, and energy productivity under AIM were improved by 11.30–12.61%. CH4 and N2O emissions and carbon footprint were reduced by 20.79%, 6.51%, and 16.39%, respectively. Compared with FEM, AIM can effectively improve the utilization efficiency of water and fertilizer resources and reduce carbon emissions. This study presents a mechanized water and fertilizer management approach suitable for large-scale rice production systems in China. By analyzing rice yield, resource utilization efficiency, and environmental benefits, AIM can serve as a crucial management strategy for enhancing productivity, economic returns, and environmental conservation within profitable rice production systems. In the future, further investigation into the impact of AIM on the microbial mechanisms underlying rice yield formation and greenhouse gas emissions is warranted.

Influence of the Long-Term Application of Management Practices (Tillage, Cover Crop and Glyphosate) on Greenhouse Gas Emissions and Soil Physical Properties

Soil treatments have a significant influence on the agricultural and environmental productivity of agricultural practices. Arable lands are one of the sources of greenhouse gas emissions (GHG) that are influenced by the chemical and physical properties of the soil and are an essential contributor to climate change. We aim to evaluate the long-term management of agricultural practices, such as different tillage systems, cover crops, and glyphosate, on GHG emissions and soil physical properties. The field trial involved three tillage systems (conventional tillage (CT), reduced tillage (RT), and no-tillage (NT)), along with variations in cover cropping (with and without cover crops) and glyphosate application (with and without glyphosate). These treatments were implemented during the cultivation of oilseed rape in 2022 as part of a cropping sequence consisting of five crops: winter wheat; winter oilseed rape; spring wheat; spring barley; and field pea. Greenhouse gas emissions (carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O)) were directly measured using a closed static chamber system. Through the examination of these management techniques, the soil’s physical properties over the studied period were assessed for their impact on GHG fluxes. The findings of the study reveal that N2O emissions were relatively low during the first month of measurement, with significant differences (p < 0.05) observed in the interaction between cover crop and glyphosate treatments. Additionally, N2O emissions were notably elevated in the reduced (0.079 µg m−2 h−1) and conventional tillage (0.097 µg m−2 h−1) treatments at the second month of measurement. Regarding CH4, increased emissions were observed in the reduced tillage and cover crop treatments. CO2 emissions exhibited variability across all of the investigated treatments. Notably, GHG fluxes spiked at the second measurement, signifying the maximum uptake of nutrients by the main plants during the growth phase. Greenhouse gas emissions leveled off across all of the treatments following the harvest, marking the end of the cultivation period. The influence of the deployed techniques varied across the determined physical parameters of the soil. The incorporation of cover crops contributed to improved water content and, further, to electrical conductivity. Glyphosate use showed no direct impact on physical properties of the soil while the different tillage treatments had varying effects on the distribution of the physical properties of the soil with respect to the degree of disturbance or tillage-induced changes. Additionally, GHG emissions were strongly correlated with precipitation at one week and two weeks before sampling, except for CO2, which showed a weaker correlation at two weeks before GHG sampling. The findings indicate that reduced and conventional tillage methods might adversely affect greenhouse gas emissions and plant functionality, particularly concerning nutrient release and uptake, especially in temperate climate conditions.

Environmental impact assessment of direct lithium extraction from brine resources: Global warming potential, land use, water consumption, and charting sustainable scenarios

Direct Lithium Extraction (DLE) has emerged as an alternative that bypasses lengthy evaporation processes to produce lithium from brine sources. This study scrutinizes both direct and indirect environmental impacts of DLE, specifically focusing on global warming, land use, and water consumption in Clayton Valley, Nevada. It was compared to traditional brine and hard rock extraction methods. The DLE method is closely tied to energy usage, and this study has explored various scenarios for power sources. The TRACI, ReCiPe, and AWARE methods of life cycle assessment were employed to evaluate the environmental footprint, indirect land use, and water footprint of lithium production from various sources. According to the study, producing one ton of lithium carbonate using the DLE method showed distinct emissions profiles. Specifically, when electricity was sourced from a diesel generator, the Nevada grid, or solar panels, the emissions totaled approximately 22, 17.3, and 7.6 tons of CO2eq, respectively. Switching power sources goes beyond affecting greenhouse gas emissions; it also influences land use impacts and individual water consumption, as evaluated in this study. The direct land use for DLE is as follows: 16, 493, 182, and 659 m²/ton of Lithium Carbonate Equivalent (LCE) for processing plant, processing plant, well field, processing plant, solar panel area, and all regions required with solar panels, respectively. In assessing the water footprint, the study determined varying water deprivation potentials depending on the electricity source utilized: 3.7 m³eq/kg of LCE with a diesel generator, 9.5 m³eq/kg of LCE with the Nevada grid, and 4.2 m³eq/kg of LCE with solar panels.

Mycorrhizosphere bacteria inhibit greenhouse gas emissions from microplastics contaminated soil by regulating soil enzyme activities and microbial community structure

Microplastics (MPs) accumulation in terrestrial ecosystems can affect greenhouse gases (GHGs) production by altering microbial and soil structure. Presently, research on the MPs effect on plants is not consistent, and underlying molecular mechanisms associated with GHGs are yet unknown. For the first time, we conducted a microcosm study to explore the impact of MPs addition (Raw vs. aged) and Trichoderma longibrachiatum and Bacillus subtilis inoculation (Sole vs. combination) on GHGs emission, soil community structure, physiochemical properties, and enzyme activities. Our results indicated that the addition of aged MPs considerably enhanced the GHGs emissions (N2O (+16%) and CO2 (+21%), respectively), C and N cycling gene expression, microbial biomass carbon, and soil physiochemical properties than raw MPs. However, the soil microbial community structure and enzyme activities were enhanced in raw MPs added treatments, irrespective of the MPs type added to soil. However, microbial inoculation significantly reduced GHGs emission by altering the expression of C and N cycling genes in both types of MPs added treatments. The soil microbial community structure, enzymes activities, physiochemical properties and microbial biomass carbon were enhanced in the presence of microbial inoculation in both type of MPs. Among sole and combined inoculation of Trichoderma and Bacillus subtilis, the co-applied Trichoderma and Bacillus subtilis considerably reduced the GHGs emission (N2O (−64%) and CO2 (−61%), respectively) by altering the expression of C and N cycling genes regardless of MPs type used. The combined inoculation also enhanced soil enzyme activities, microbial community structure, physiochemical properties and microbial biomass carbon in both types of MPs treatment. Our findings provide evidence that polyethylene MPs likely pose a high risk of GHGs emission while combined application of Trichoderma and Bacillus subtilis significantly reduced GHGs emission by altering C and N cycling gene expression, soil microbial community structure, and enzyme activities under MPs pollution in a terrestrial ecosystem.

Hydrochar from dairy sludge as phosphorus fertiliser affects greenhouse gas emissions and maize yield

ABSTRACT Dairy processing sludge is a phosphorus (P) rich waste with a high potential to replace mineral phosphorus fertiliser in crop production, with possible enhancement of greenhouse gas emissions to the environment. Hydrothermal carbonisation is a technology that transforms the sludge into a hydrochar. The objective of this study is examining P availability of two hydrochars produced from Danish and Irish dairy sludge and their influence on greenhouse gas emissions and maize yields. The trial assessed (i) Danish dairy sludge; (ii) hydrochar derived from Danish sludge; (iii) hydrochar made from Irish dairy sludge; (iv) mineral phosphorus fertiliser; and (v) control. Emissions of nitrous oxide and carbon dioxide, soil pH, mineral nitrogen contents and crop yields were measured. Treatment with Danish dairy sludge had significantly higher cumulative nitrous oxide emissions while the emissions from both hydrochars were not significantly different compared to mineral phosphorous feriliser. Statistical modelling showed that temperature, soil nitrate content, interactions both between temperature and precipitation, and between soil moisture and precipitation were drivers for nitrous oxide emissions. There was no difference in emissions among all treatments when scaled for yield. Hydrochar may alleviate the enhanced nitrous oxide emissions in soil without constraining P availability and maize crop yields.

Polyethylene microplastic-induced microbial shifts affected greenhouse gas emissions during litter decomposition in coastal wetland sediments

Microplastic contamination has become increasingly aggravated in coastal environments, further affecting biogeochemical processes involved with microbial community shifts. As a key biogeochemical process mainly driven by microbiota in coastal wetland sediments, litter decomposition contributes greatly to the global greenhouse gas (GHG) budget. However, under microplastic pollution, the relationship between microbial alterations and GHG emissions during litter decomposition in coastal wetlands remains largely unknown. Here, we explored the microbial mechanism by which polyethylene microplastic (PE-MP) influenced greenhouse gas (i.e., CH4, CO2 and N2O) emissions during litter decomposition in coastal sediments through a 75-day microcosm experiment. During litter decomposition, PE-MP exposure significantly decreased cumulative CH4 and CO2 emissions by 41.07% and 25.79%, respectively. However, there was no significant change in cumulative N2O emissions under PE-MP exposure. The bacterial, archaeal, and fungal communities in sediments exhibited varied responses to PE-MP exposure over time, as reflected by the altered structure and changed functional groups of the microbiota. The altered microbial functional groups ascribed to PE-MP exposure and sediment property changes might contribute to suppressing CH4 and CO2 emissions during litter decomposition. This study yielded valuable information regarding the effects of PE-MP on GHG emissions during litter decomposition in coastal wetland sediments.

Assessing the Impact of Digitalization, Tax Revenues, and Energy Resource Capacity on Environmental Quality: Fresh Evidence from CS-ARDL in the EKC Framework

This study examines the dynamic relationships between digitalization, environmental tax revenues, and energy resource capacity within the framework of the Environmental Kuznets Curve (EKC), focusing on their combined impact on environmental quality. It employs a cross-sectional augmented autoregressive distributed lag (CS-ARDL) approach, an advanced technique for complex panel data that is specifically designed to address issues of cross-sectional dependence and slope heterogeneity inherent in panel data analysis. The research covers 88 countries, including both low- and middle-income countries (LMICs) and high-income countries (HICs), to understand how digitalization, as a driving force of the Fourth Industrial Revolution, interacts with environmental taxation and energy resource management to affect greenhouse gas emissions. The results reveal distinct effects of environmental taxes and energy capacity on environmental quality, with marked differences between LMICs and HICs. In HICs, technological progress, especially in information and communication technology (ICT), is found to contribute significantly to environmental quality. For LMICs, the effects are less evident, and the findings suggest the need for tailored strategies in environmental policy and energy management. By providing empirical evidence on the differential impacts of digitalization and energy policies in different economic contexts, this research enriches the environmental economics discourse. It highlights the need for policy frameworks tailored to specific contexts that effectively balance economic growth with sustainable development goals, thereby providing insightful implications for achieving the Sustainable Development Goals (SDGs).

Driving and limiting factors of CH4 and CO2 emissions from coastal brackish-water wetlands in temperate regions

Abstract. Coastal wetlands play a fundamental role in mitigating climate change thanks to their ability to store large amounts of organic carbon in the soil. However, degraded freshwater wetlands are also known to be the first natural emitter of methane (CH4). Salinity is known to inhibit CH4 production, but its effect in brackish ecosystems is still poorly understood. This study provides a contribution to understanding how environmental variables may affect greenhouse gas (GHG) emissions in coastal temperate wetlands. We present the results of over 1 year of measurements performed in four wetlands located along a salinity gradient on the northeast Adriatic coast near Ravenna, Italy. Soil properties were determined by coring soil samples, while carbon dioxide (CO2) and CH4 fluxes from soils and standing waters were monitored monthly by a portable gas flux meter. Additionally, water levels and surface and groundwater physical–chemical parameters (temperature, pH, electrical conductivity, and sulfate concentrations of water) were monitored monthly by multiparametric probes. We observed a substantial reduction in CH4 emissions when water depth exceeded the critical threshold of 50 cm. Regardless of the water salinity value, the mean CH4 flux was 5.04 gm-2d-1 in freshwater systems and 12.27 gm-2d-1 in brackish ones. In contrast, when water depth was shallower than 50 cm, CH4 fluxes reached an average of 196.98 gm-2d-1 in freshwater systems, while non-significant results are available for brackish/saline waters. Results obtained for CO2 fluxes showed the same behavior described for CH4 fluxes, even though they were statistically non-significant. Temperature and irradiance strongly influenced CH4 emissions from water and soil, resulting in higher rates during summer and spring.

Temporary stratification promotes large greenhouse gas emissions in a shallow eutrophic lake

Abstract. Shallow lakes and ponds undergo frequent temporary thermal stratification. How this affects greenhouse gas (GHG) emissions is moot, with both increased and reduced GHG emissions hypothesised. Here, weekly estimations of GHG emissions, over the growing season from May to September, were combined with temperature and oxygen profiles of an 11 ha temperate shallow lake to investigate how thermal stratification shapes GHG emissions. There were three main stratification periods with profound anoxia occurring in the bottom waters upon isolation from the atmosphere. Average diffusive emissions of methane (CH4) and nitrous oxide (N2O) were larger and more variable in the stratified phase, whereas carbon dioxide (CO2) was on average lower, though these differences were not statistically significant. In contrast, there was a significant order of magnitude increase in CH4 ebullition in the stratified phase. Furthermore, at the end of the period of stratification, there was a large efflux of CH4 and CO2 as the lake mixed. Two relatively isolated turnover events were estimated to have released the majority of the CH4 emitted between May and September. These results demonstrate how stratification patterns can shape GHG emissions and highlight the role of turnover emissions and the need for high-frequency measurements of GHG emissions, which are required to accurately characterise emissions, particularly from temporarily stratifying lakes.

Environmental parameters and management as factors affecting greenhouse gas emissions from clay soil

ABSTRACT Greenhouse gas emissions (GHG) drive climate change, with agricultural land significantly contributing, influenced by soil properties. While extensive research exists on environmental and management impacts on GHG emissions across various soils and climates, understanding key factors influencing GHG emissions from clay soil in temperate climates is limited. This study aims to investigate the combination of environmental and management factors reducing N2O, CO2, and CH4 emissions from clay soil in temperate climates. Recognising the potential of reduced tillage and legume-based crop rotations in mitigating GHG emissions, we investigate their impact on soil emissions. The conventionally managed field with spring barley, field beans, winter wheat, and winter rapeseed rotation demonstrates the lowest average N2O emission (3.7 g N2O ha−1 d− 1), while the field with winter crops in a reduced tillage rotation shows the highest N2O emission (8.5 g N2O ha−1 d− 1). A rotation with winter crops, beans twice, and barley, under conventional management, demonstrates the highest CO2 emission (140.2 kg CO2 ha−1 d− 1), while the lowest CO2 emission is observed in a rotation with winter crops, beans, and barley under reduced tillage management (100.8 kg CO2 ha−1 d− 1). CH4 assimilation ranges from 3.1 to 5.4 CH4 g ha−1 d−1 across all rotation and tillage combinations. However, ANCOVA results indicate that the volumes of GHG emissions are significantly influenced by the interaction of environmental and management factors, where precipitation is the most significant factor in the interaction with other environmental factors, soil tillage, and crop residues for N2O and CO2 emissions, while CH4 emissions are influenced by the interaction of air temperature with other environmental factors, soil tillage, and crop residues. This underscores the need to consider both management and relevant environmental factors when evaluating the impact of practices on GHG emissions from clay soil in temperate climates.