Greenhouse Gas Production Research Articles

THE ROLE OF INTERNATIONAL AGREEMENTS IN CLIMATE POLICY

Climate change is one of the greatest environmental challenges of our time. Climate change can occur as a result of natural processes on Earth (e.g., tectonic motion of continents), as a result of external influences on the planet (e.g., changes in the intensity of solar radiation), or even as a result of human activity (e.g., greenhouse gas production). Human activities have boosted emissions of carbon dioxide, pushing up the temperatures. One potential impact is extreme weather and melting polar ice. There are natural climate fluctuations, but it is a fact that temperatures are growing higher now than at many other periods. This is related to the greenhouse effect which describes how some of the Sun's energy is trapped in the Earth's atmosphere. Solar energy from the Earth's surface, radiating back to space, is absorbed by greenhouse gases and re-emitted in every direction. This present paper discusses the impact of climate change and summarises the role of legal regulations in the process of this major environmental problem.

Impact of biochar on greenhouse gas emissions and soil carbon sequestration in corn grown under drip irrigation with mulching

Biochar is widely used as a soil amendment to challenge climate change through restraining greenhouse gas production and increasing soil C sink in cropland soils, yet its effect was not studied well under drip irrigation with mulch. A two-year field experiment was conducted to investigate the impact of corn residue-derived biochar amendments on greenhouse gases (GHG), soil organic carbon (SOC), and global warming potential (GWP) on sandy loam soil in Inner Mongolia, China. Biochar application rates of 0 (B0, control), 15 (B15), 30 (B30), and 45 (B45) t ha−1 were broadcasted onto the soil surface, and then mixed into 30-cm soil depth at the first crop growing season to a film-mulched and drip-irrigated corn production. Soil emissions of CO2, N2O, and CH4 were measured using a closed static chamber approach. Compared to control plots, biochar amendments reduced total CO2 emission by 18–25% at the first growing season, and 19–41% at the second growing season. The highest and lowest CH4 emissions were from B45 and B15 in the first year, and B45 and B30 in the second year, respectively. Relative to the control, B15 and B30 reduced CH4 emission by 124% and 132% as averaged over 2-yr. With biochar amendments, total N2O emission was decreased by 71–110% and 39–47% in the first and second year. Among these biochar amendments, B30 was the best amendment limiting the GWP of N2O and CH4 in any of the two years. B30 and B45 significantly increased SOC sequestration in the top 15-cm depth by 19% and 37% in the first growing season, respectively, and by 12% and 15% in the second growing season. Biochar amendment B30 also significantly increased corn yields. Biochar shows the greatest potential to mitigate greenhouse gas emissions and increase soil C sequestration. The greatest reductions with biochar application 30 t ha−1 in corn.

Potential of methane and carbon dioxide in vitro production by Urochloa hybrid subjected to periods of coexistence with weeds

The increased world population has raised the demand for animal proteins, forcing livestock to become productive, efficient, and environmentally sustainable. This study aimed to assess the effect of weed coexistence on productivity, nutritional quality, and potential production of greenhouse gases (GHG) by Convert HD364 grass (Urochloa hibrida cv. Mulato II) under pasture renovation conditions. The experiment was carried out in a randomized block design with four replications and treatments consisting of eight coexistence periods: 0, 15, 30, 45, 60, 75, 90, and 120 days after seedling emergence. Phytosociological assessments were performed in the weed community at the end of each coexistence period. The Convert HD364 grass was assessed for the morphological and chemical-bromatological parameters and for the GHG emission potential. Productivity, nutritional quality, and energy value of the Convert HD364 grass decreased proportionally with the increased period of weed coexistence. The non-coexistence with weeds results in a better in vitro digestibility of organic matter and, consequently, decreases the potential of GHG emission by the dry matter of the Convert HD364 grass.

Litter removal enhances soil N2O emissions: Implications for management of leaf-harvesting Cinnamomum camphora plantations

Nitrous oxide (N2O) and carbon dioxide (CO2) contribute substantially to global climate. Understanding N2O and CO2 emission intensity from forest soil is important for greenhouse gas (GHG) budget and climate change mitigation. Litter decomposition and nitrogen (N) addition are two crucial factors impacting soil GHG production, but magnitude depends on litter characteristics. Cinnamomum camphora is used for leaf-harvesting for essential oil extractions, which may disturb litter input and hence soil GHG emissions. We conducted an in situ study over fourteen months in C. camphora plantations to compare litter removal to litter control, combined with N addition, quantify production of N2O and CO2 in full-factorial complete-randomized design. Soil N2O emission rates were significantly influenced by litter and N treatment, while CO2 emissions were only impacted by interactions between litter and N treatment. Specifically, soil N2O emission rates were increased by 681%, while copy number of five functional microbial genes associated with N2O productions were increased by 2.8 to 71.4 times following litter removal. C. camphora litter might have released chemicals associated with inhibition of related microbial activities. Soil CO2 emission rates were 25% higher with litter removed and 34% lower with litter when N was added, further indicating inhibition effects of C. camphora litter on microbial activities. In future management of C. camphora plantations with intensive defoliation management and fertilization practice, litter regimes with more litter input should be considered in mitigation of soil GHG emissions, and hence global climate change.

Diel variation of CH4 and CO2 dynamics in two contrasting temperate lakes

ABSTRACT The concurrent short-term fluctuations of methane (CH4) and carbon dioxide (CO2) concentrations and emissions in lakes are not well studied. Quantifying the differences in daytime versus nighttime dynamics may provide information about the controls over greenhouse gas production and may have relevance to lake carbon budgets. In this study, the diel variation of CH4 and CO2 emissions and concentration patterns were determined along the water column of 2 temperate lakes with different trophic states during July 2015. The results showed that the shallow eutrophic lake had significantly higher CH4 and CO2 releases than the deep oligo-mesotrophic lake. No significant diel fluctuations were observed in atmospheric CH4 emissions from either lake or in CO2 emission from the oligo-mesotrophic lake, but significantly higher CO2 emission from the eutrophic lake occurred during the daytime compared to nighttime. Based on a diffusion–reaction model, it was possible to estimate the diel variation of the sources and sinks of dissolved CH4 throughout the water column, suggesting lateral transport is a potential source of CH4 in oxygenated water layers in the oligo-mesotrophic lake. Sources and sinks throughout the water column should be considered in future studies for a better understanding of CH4 dynamics within the lakes.

Mechanisms of Carbon Sequestration in Highly Organic Ecosystems - Importance of Chemical Ecology.

Organic matter decomposition plays a major role in the cycling of carbon (C) and nutrients in terrestrial ecosystems across the globe. Climate change accelerates the decomposition rate to potentially increase the release of greenhouse gases and further enhance global warming in the future. However, fractions of organic matter vary in turnover times and parts are stabilized in soils for longer time periods (C sequestration). Overall, a better understanding of the mechanisms underlying C sequestration is needed for the development of effective mitigation policies to reduce land‐based production of greenhouse gases. Known mechanisms of C sequestration include the recalcitrance of C input, interactions with soil minerals, aggregate formation, as well as its regulation via abiotic factors. In this Minireview, we discuss the mechanisms behind C sequestration including the recently emerging significance of biochemical interactions between organic matter inputs that lead to C stabilization.

Life cycle assessment of wafer biscuit production

The Life Cycle Assessment (LCA) method was used to determine the amount of potential emissions generated from the production activities of the wafer biscuit. The objectives of this study were (1) to observe all of input and output of the production process, (2) to analyze the potential of environmental impacts, (3) and to provide alternative improvements in efforts to reduce the environmental impacts. The LCA method consisted of four stages: determination of goal and scope definition, inventory analysis, impact assessment analysis, and interpretation analysis. Based on observations of existing activities, the scope of this research was set for “gate to gate” and the impact analysis included global warming potential, eutrophication, and acidification. The results of the impact analysis showed that production of wafer biscuit produced greenhouse gas (GHG) emissions of 1.5161 kg-CO2-eq/kg-product, acidification of 0.0115 kg-SO2-eq/kg-product, and eutrophication of 0.0131 kg-PO4 3−eq/kg-product. There were four alternative improvements that should be done to reduce environmental impacts; (1) the use of solar water heater which could decrease GHG emissions by 8%, acidification by 13%, and eutrophication by 0.56%, (2) replacement of refrigerant types could lower GHG emissions by 19%, acidification of 13%, and eutrophication of 0.57%, (3) reuse of cooling water reduced GHG emissions by 7%, acidification by 11%, and eutrophication by 32.21%, and (4) improvement in waste treatment would reduce emissions eutrophication as much as 83.86%.

Novel Polyurethane-Catalyzed Cyclic Carbonate Synthesis Using CO2 and Epoxide

The conversion of industrially produced greenhouse gases, like CO2, into value-added chemicals is economically beneficial to industry and vital for environmental conservation. However, the conditio...

THE NEXUS OF CLIMATE CHANGE AND DEVELOPMENT: THE ROLE OF MEDIA IN PAKISTAN

Pakistan is facing two front challenges from climate change and development. It has the least share in production of Green House Gases (GHGs) as well as in Carbon Offset and on the other hand, it is the country which is worst affected by climate change among South Asian countries. Similarly, the cost of sustainable development hinders the growth of Gross Domestic Products (GDP). The electronic and printed media in Pakistan is more focused on the causes and impacts of climate change as well as on the progress of sustainable Development Goals (SDGs). The present study explores the diverse dimensions of the role of media in the understanding of the nexus of climate change and development to maximize the benefits for the country development particularly of GDP sector. The existing potential of Pakistani media is studied to interlink the GHGs emission and GDP, with the impacts of climate change and Carbon Offset take down by the country. In the same fashion, the relation between sustainable development and growth of GDP with inflation rate portrayed the actual struggle of the country for the SDGs progress. The paradigm shift in understanding and projecting of the nexus of climate change and development from Pakistani media will support the growth of GDP in the country.

Could Cryoturbic Diapirs Be Key for Understanding Ecological Feedbacks to Climate Change in High Arctic Polar Deserts?

AbstractHigh Arctic polar deserts cover 26% of the Arctic. Increasing temperatures are predicted to significantly alter polar desert freeze‐thaw and biogeochemical cycles, with important implications for greenhouse gas emissions. However, the mechanisms underlying these changing cycles are still highly uncertain. Cryoturbic, carbon‐rich Bhy horizons (diapirs) in frost boils are key nutrient sources for Salix arctica. We hypothesized that diapirism leads to organic carbon characteristics that alter microbial pathways, which then control root foraging and greenhouse gas production. During July and August 2013, we characterized soil properties and examined gross nitrogen transformation rates in frost boils both with and without diapirs in two High Arctic polar deserts (dolomite and granite) near Alexandra Fjord (78°51′N 75°54′W), Ellesmere Island, Nunavut, Canada. Diapiric frost boils had 18% higher soil organic carbon in the dolomitic and 9% higher in the granitic deserts, and 29% higher total dissolved nitrogen in the dolomitic desert. However, diapirs decreased gross nitrogen mineralization rates by 30% in the dolomitic and by 48% in the granitic deserts. Attenuated total reflectance Fourier transformed mid‐infrared spectroscopy revealed greater concentrations of polysaccharides and recalcitrant carbon in diapiric versus nondiapiric frost boils. These increased polysaccharide concentrations likely facilitate diapirism as soil viscosity increases with polysaccharides. Lower microbial activity or ectomycorrhizae that are known to colonize S. arctica may accumulate total dissolved nitrogen in diapirs. Our results suggest geomorphologic‐plant‐microbe interactions may underlie important patterns of geochemical cycling in arctic systems. Thus, polar desert frost boils should represent a key focus of future investigations of climate change in arctic systems.

Determinants of individual vehicle type choice and energy consumption in a heavy traffic metropolis of Southeast Asia featuring the case of Metro Manila

Sustained economic growth with insufficient public transport in metropolitan areas encourages private vehicle dependency, thereby increasing petroleum oil consumption and greenhouse gas (GHG) production. One way to mitigate these issues is to encourage private vehicle users to own smaller fuel-efficient vehicles. This paper intends to explore determinants (i.e., socio-economic characteristics, travel behavior, vehicle attributes and purchasing conditions, vehicle and gas prices, and built environment characteristics) of individual vehicle type owners and energy consumption in Metro Manila. The data sample of 846 observations and a copula-based joint discrete-continuous framework were employed. The findings highlighted that individuals using bank auto loans are more likely to choose SUVs than cars, thereby consuming more energy. Furthermore, people located in high population density areas and those with road-based public transport line dense areas prefer cars to SUVs. An increase in gas and vehicle cost contributes to energy saving and discourages SUV dependency. The developed models were also applied for a “what-if” scenario analysis to quantify the competing options as an innovative perspective for crafting proactive transportation policies. Understanding the determinants of vehicle type ownership and energy consumption is the precursor of designing consistent transportation policies to mitigate petroleum oil consumption and mobile emissions.

Cacao leaf litter decomposition under different moisture and pH: Characteristic of soil N mineralization (NH4 + and NO3 −) and Greenhouse gas CO2, CH4, N2O flux emission

Plants litter as soil organic matter turn over to soil by the decomposition process. Decomposition is regulated by environmental factors, such as soil water content and pH. High water content (90%) and pH 6.2 increased CO2 gas production rate, lowest water content (30%) and pH 4.9 increased NH4 + N-mineralization into the soil as decomposition result. In this study, we investigated cacao leaf litter decomposition in soil. Cacao leaf litter was applied in a 100 mL polypropylene bottle with 70 g air-dried soil, but only the soil was applied as a control. For the litter-amended treatments, 2 g (oven-dry weight) with 2 mm sized cacao leaf litter was placed on the soil surface. The treatment with different soil moisture and pH regimes were soil moisture and pH of 30% and 4.9 (SLWC30i), 30% and 6.2 (SLWC306), 60% and 4.9 (SLWC60i), 60% and 6.2 (SLWC606), 90% and 4.9 (SLWC90i), 90% and 6.2 (SLWC906), respectively. All treatment was incubated at 25°C under the dark condition for 28 days. Extractable NO3 − and NH4 + concentration, and soil greenhouse gas (CO2, CH4, N2O) were measured. Highest extractable NO3 − and NH4 + concentration showed in SWC906 (30.7 mg N kg−1) and SLWC606 (87.1 mg N kg−1), respectively. Soil greenhouse gas production rate highest in water content 90% pH 6.2, CO2 was 3.82 kg C period−1, CH4 was 0.0089 kg C period−1, N2O was 0.016 kg N period−1.

Decreasing organic carbon bioreactivity in European rivers

Abstract European rivers experience increased loading of total organic carbon (TOC) from terrestrial sources due to factors involving changes in land use, climate and soil acidity. However, little is known about how increased TOC is linked to changes in the bioreactivity of organic matter in these rivers on a continental scale. We compiled paired measurements of TOC and biological oxygen demand in 5‐day 20°C dark incubations from 3,486 EU monitoring rivers. Assuming first‐order decay and a fixed respiratory quotient, annual average TOC and biological oxygen demand values were used to calculate 11,060 values of the decay coefficient k. The k decreased by two orders of magnitude as a power function of increasing TOC. This relationship could partly be explained by carbon quality, as the C:N ratio of the organic matter was the lowest in high‐reactivity low‐TOC rivers, and vice versa. A trend analysis showed that TOC increased by 18% from 1996 to 2012, while k decreased by as much as 50%. As a consequence, the biological oxygen demand in the water decreased over time in spite of the water browning trend (increased TOC). Together, these results suggest that reactivity is low near terrestrial hot spots for TOC export, and low during years with high terrestrial TOC loading, but increases in rivers with low TOC concentrations where internal processes in the water have high relative influence on bulk TOC quality. Thus, browning of European freshwaters is linked to strong decreases in TOC reactivity on a continental scale, suggesting that the impacts of browning on microbial water deoxygenation and greenhouse gas production are less severe than previously thought.

Functional interactions between posttranslationally modified amino acids of methyl-coenzyme M reductase in Methanosarcina acetivorans.

The enzyme methyl-coenzyme M reductase (MCR) plays an important role in mediating global levels of methane by catalyzing a reversible reaction that leads to the production or consumption of this potent greenhouse gas in methanogenic and methanotrophic archaea. In methanogenic archaea, the alpha subunit of MCR (McrA) typically contains four to six posttranslationally modified amino acids near the active site. Recent studies have identified enzymes performing two of these modifications (thioglycine and 5-[S]-methylarginine), yet little is known about the formation and function of the remaining posttranslationally modified residues. Here, we provide in vivo evidence that a dedicated S-adenosylmethionine-dependent methyltransferase encoded by a gene we designated methylcysteine modification (mcmA) is responsible for formation of S-methylcysteine in Methanosarcina acetivorans McrA. Phenotypic analysis of mutants incapable of cysteine methylation suggests that the S-methylcysteine residue might play a role in adaption to mesophilic conditions. To examine the interactions between the S-methylcysteine residue and the previously characterized thioglycine, 5-(S)-methylarginine modifications, we generated M. acetivorans mutants lacking the three known modification genes in all possible combinations. Phenotypic analyses revealed complex, physiologically relevant interactions between the modified residues, which alter the thermal stability of MCR in a combinatorial fashion that is not readily predictable from the phenotypes of single mutants. High-resolution crystal structures of inactive MCR lacking the modified amino acids were indistinguishable from the fully modified enzyme, suggesting that interactions between the posttranslationally modified residues do not exert a major influence on the static structure of the enzyme but rather serve to fine-tune the activity and efficiency of MCR.

The international political economy of nature and society: from climate emergency to climate justice in our common home

Longitudinal scientific evidence proves beyond any reasonable doubt that the problem of climate change is reaching a point of no return, upon which Earthly and human survival depends. The major contributors of climate change include industry, transportation, agriculture, and consumers, over which corporate globalization controls, which consume fossil fuels, such as oil, coal, and gas that produce greenhouse gases. Climate change impacts access to clean water, human health, forests, coastal areas, biodiversity, and agriculture. Our tasks ahead include: 1) exposing and opposing flawed economic, political, social, cultural, and security models that destroy nature, cause mal-development, and widening the gap between the rich and the poor and 2) proposing new cooperative models that put sustainability and equality—nature and people—first, especially the poor and the oppressed, before profits.

The Long-Term Relationship between Microbial Metabolism and Greenhouse Gases.

The production and consumption of the potent greenhouse gases, nitrous oxide and methane, are largely controlled by microorganisms that have long been assigned to defined functional guilds. However, our understanding of how microbial and biogeochemical processes interact to control the flux of these gases has expanded in recent years. The consumption and production of nitrous oxide and methane are functionally intertwined and engage a range of other biogeochemically active molecules from oxic to anoxic ecosystems. Abiotic processes, such as reaction of nitrogen oxides with metals, have a strong influence on microorganisms and play an equally significant role in greenhouse gas flux. The complex enzymology and physiology of microbial greenhouse gas metabolism are explored and discussed in the context of geochemistry and climate change.

Disentangling the effects of methanogen community and environment on peatland greenhouse gas production by a reciprocal transplant experiment

Abstract Northern peatlands consist of a mosaic of peatland types that vary spatially and temporally and differ in their methane (CH4) production. Microbial community composition and environment both potentially control the processes that release carbon from anoxic peat either as CH4 or as carbon dioxide (CO2), a less potent greenhouse gas than CH4. However, the respective roles of these controls remain unclear, which prevents incorporating microbes in the predictions of peatland CH4 emissions. Here, a reciprocal transplant experiment was carried out to separate the influences of microbial community and environment in CH4 and anaerobic CO2 production. Peat from an acidic Sphagnum bog and a sedge fen with higher pH was enclosed in membrane bags with a pore size of 0.2 µm, preventing microbial colonization from the outside, and transplanted in the field for 2 months. Potential CH4 production was primarily controlled by the environment. The conditions in the bog suppressed the initially higher activity of fen methanogens and reduced CH4 production by 79%. Against expectations, the inhibition was not specific to acetate‐using Methanotrichaceae. Reciprocal transplantation favoured Methanosarcinaceae and potentially methylotrophic methanogenesis in general. Bog methanogens, mostly hydrogenotrophic Methanoregulaceae, retained their community structure and activity in the fen with a slight increase (+37%) in CH4 production. Anaerobic CO2 production was controlled by both the microbial community and the environment. Transplantation led to increased CO2 production in both bog (+50%) and fen peat (+57%) with distinct bacterial community, showing that the new environment directed more carbon to other anaerobic processes than methanogenesis. Taken together, these results relate differences in CH4 production of bogs and fens to ecophysiology of specific methanogen groups. The sensitiveness of fen methanogens to the acidic conditions in Sphagnum bogs can help explain the decrease in CH4 emission in the typical boreal peatland succession from young fens to older bogs. Increase in anaerobic CO2 versus CH4 production with transplantation shows that disturbances of boreal peatlands can activate poorly defined pathways of anaerobic decomposition. A free Plain Language Summary can be found within the Supporting Information of this article.

Multiple trade‐offs between maximizing yield and minimizing greenhouse gas production in Chinese rice croplands

AbstractGlobally, paddy fields are a major anthropogenic source of greenhouse gas (GHG) emissions from agriculture. There is, however, limited understanding of relationships between GHG production with fertilizer management, rice varieties, and soil variables. This information is crucial for minimizing the climatic impacts of rice agriculture. Here, we examined the relationships between soil GHG production and management practices throughout China. The current doses of N‐fertilizer (73–272 kg ha−1) were negatively correlated with rice yield and with CO2 or CH4 production and positively correlated with N2O production, thus suggesting N‐overfertilization. Impacts on soil traits such as decreasing pH or the availabilities of other nutrients could be underlying these relationships. Rice yield was highest, and GHG production was lowest at sites using intermediate levels of P‐ and K‐fertilization. CO2 and CH4 production and emissions were positively related with soil water content. The yield was higher, and N2O productions were lower at the sites with japonica rice. Our results strongly suggest that current high doses of N‐fertilizers could be reduced to thus avoid the negative effects of excessive N input on GHG production without any immediate risk of rice production loss. Current intermediate doses of P‐ and K‐fertilization should be adopted across China to further improve rice production without the risk of GHG emissions. The use of different rice varieties and strategies of water management should be reexamined in relation to crop production and GHG mitigation.

Evolution and Future Needs of Food Chemistry in a Changing World.

The agriculture system is tasked with the responsibility to deliver adequate quantities of food, which meet national needs, provide health benefits, and deliver these in an environmentally sustainable system. Efforts by the food industry to deliver safe and nutritious foods, which also improve health and wellness, are complicated by a constantly changing landscape. As early as the 1950s, fat in diets was a concern, and in the 1980s and early 1990s, fat was an evil component in foods. In response, the industry developed zero/low fats and foods and low-fat foods. The evolution in dietary guidelines in the 2000s has evolved to greater concern over simple sugars and starches as negative sources of calories in an environment of increasing obesity. With the world population approaching 9 billion individuals by 2050, food production, which relies on large amounts of water and energy, must become more efficient. Food production and delivery also must find innovative ways to reduce food waste, environmental pollutants, and greenhouse gas production. The nexus of food, energy, and water is and will continue to be a major research and political and communication emphasis for the scientific community. We must find clear and consumer friendly communications to explain the utilization of modern technology in food production. Solutions to these issues must also include sustainably produced, safe, nutritious, satisfying, and wholesome foods.

Methane and nitrous oxide porewater concentrations and surface fluxes of a regulated river.

Greenhouse gas (GHG) emissions from rivers are a critical missing component of current global GHG models. Their exclusion is mainly due to a lack of in-situ measurements and a poor understanding of the spatiotemporal dynamics of GHG production and emissions, which prevents optimal model parametrization. We combined simultaneous observations of porewater concentrations along different beach positions and depths, and surface fluxes of methane and nitrous oxide at a plot scale in a large regulated river during three water stages: rising, falling, and low. Our goal was to gain insights into the interactions between hydrological exchanges and GHG emissions and elucidate possible hypotheses that could guide future research on the mechanisms of GHG production, consumption, and transport in the hyporheic zone (HZ). Results indicate that the site functioned as a net source of methane. Surface fluxes of methane during river water stages at three beach positions (shallow, intermediate and deep) correlated with porewater concentrations of methane. However, fluxes were significantly higher in the intermediate position during the low water stage, suggesting that low residence time increased methane emissions. Vertical profiles of methane peaked at different depths, indicating an influence of the magnitude and direction of the hyporheic mixing during the different river water stages on methane production and consumption. The site acted as either a sink or a source of nitrous oxide depending on the elevation of the water column. Nitrous oxide porewater concentrations peaked at the upper layers of the sediment throughout the different water stages. River hydrological stages significantly influenced porewater concentrations and fluxes of GHG, probably by influencing heterotrophic respiration (production and consumption processes) and transport to and from the HZ. Our results highlight the importance of including dynamic hydrological exchanges when studying and modeling GHG production and consumption in the HZ of large rivers.