Gas Emissions Research Articles

Assessing Carbon Carrying Capacity of Forest Ecosystem: A Case Study in West Sumatera Province

All attempts have been taken by majority nations to reduce and invent the greenhouse gases (GHG) emission, but none of them provide any quantitative framework to assess ecosystem capacity for carrying carbon. To measure ecosystem boundaries to offset carbon and how far the emission has exceeded beyond them, this paper aims to calculate the carbon carrying capacity and evaluate its availability to sequester CO2 emission in a certain area. Considering forests, the major carbon reservoir to be the key ecosystem and taking West Sumatera Province in Indonesia as the case study, the Carbon Carrying Capacity (CCC) assessment is conducted with ecological footprint concept through carbon capacity surplus-deficit. The results show the forest CCC was fluctuated which were the highest 3.9 million ton in 2016 and the lowest 2.4 million ton in 2019, and primary mangrove land cover was the biggest carbon sequesters for 114 ton C/ha every year. The forest CCC was dominantly deficit which interpreted as limited and unavailable forest capacity to offset carbon emission. To improve forest CCC, forest area needs to be conserved, also develop low-carbon and green economic transformation to reduce GHG emission. The local society can take role to conserve the forest through customary laws application, then the government ought to plan spatial strategies through limiting land use for the primary forest and prohibiting mangrove and swamp forest conversion, also monitor, control and make legal approach to achieve national targets on reducing CO2 emission.

An AIS-Based Study to Estimate Ship Exhaust Emissions Using Spatio-Temporal Approach

The global shipping industry facilitates the movement of approximately 80% of goods across the world but accounts for nearly 3% of total greenhouse gas (GHG) emissions every year, and other pollutants. One challenge in reducing shipping emissions is understanding and quantifying emission characteristics. A detailed method for calculating shipping emissions should be applied when preparing exhaust gas inventory. This research focused on quantifying CO2, NOx, and SOx emissions from tankers, containers, bulk carriers, and general cargo in the Republic of Korea using spatio-temporal analysis and maritime big data. Using the bottom-up approach, this study calculates vessel emissions from the ship engines while considering the fuel type and operation mode. It leveraged the Geographic Information System (GIS) to generate spatial distribution maps of vessel exhausts. The research revealed variability in emissions according to ship types, sizes, and operational modes. CO2 emissions were dominant, totaling 10.5 million tons, NOx 179,355.2 tons, and SOx 32,505.1 tons. Tankers accounted for about 43.3%, containers 33.1%, bulk carriers 17.3%, and general cargo 6.3%. Further, emissions in hoteling and cruising were more significant than during maneuvering and reduced speed zones (RSZs). This study contributes to emission databases, providing a basis for the establishment of targeted emission control policies.

Understanding Food Waste Sorting Practices: Insights from a Systematic Review

Approximately 2.5 billion tons of waste are generated annually worldwide, with food waste constituting a significant portion: 88 million tons in the European Union (EU) alone. Food waste has severe societal, economic, and environmental consequences, contributing 15–16% of greenhouse gas (GHG) emissions from the food supply chain. In response, many countries, including EU member states, the United States of America (USA), and China, have introduced policies mandating food waste sorting. These regulations are informed by scientific research on waste prevention, environmental impact assessments, and cost–benefit analyses of waste reduction strategies. For example, studies on organic waste treatment technologies, economic incentives for waste sorting, and the effectiveness of landfill bans have influenced the development of the EU Waste Framework Directive (2008/98/EC), China’s National Waste Classification Policy (2017), and the USA Food Recovery Act (2015). As waste management continues to evolve, understanding the economic, technological, and policy dimensions of food waste sorting remains crucial for achieving sustainable development and circular economy goals globally. This study systematically reviews the international literature on food waste sorting, analyzing sorting behaviors and identifying theoretical frameworks that explain these behaviors. Using the PSALSAR systematic review methodology, 67 relevant studies from diverse geographic regions were analyzed. The findings highlight the critical influence of external factors in shaping sorting behaviors, such as financial incentives and infrastructure, alongside internal drivers, such as environmental awareness and social norms. While external measures often yield immediate compliance, internal motivation fosters long-term behavioral changes. Moreover, significant regional and cultural variations in food waste sorting practices were identified. The Theory of Planned Behavior (TPB) emerged as a dominant framework in the study of waste sorting behaviors, often complemented by other models such as Social Cognitive Theory (SCT). Policy recommendations emphasize the need for tailored interventions that address regional and demographic differences, community-driven educational initiatives, and the integration of innovative waste sorting technologies. Future research should focus on assessing the economic and psychological impacts of waste sorting policies across different socio-cultural contexts and exploring innovative strategies to enhance global public participation in food waste management.

Assessment of airborne pollutants in wastewater treatment plants.

Wastewater generation rates have increased considerably in recent years due to population growth, urbanisation, and industrialisation. Although wastewater treatment plants (WWTPs) play a crucial role in purifying wastewater and mitigating industrial and domestic pollution in global freshwater reserves, their impact on air quality in nearby areas is frequently neglected. Therefore, this study assessed air quality in two WWTPs in Toledo, Spain. One is located in an industrial area and processes both industrial and domestic sewage (WWTP1), and the other is situated in a rural area and treats domestic wastewater (WWTP2), handling approximately double the treatment flow. Moreover, the aeration systems in the bioreactors differ. Measurements were made over a period of 6 months and included levels of gaseous emissions, such as SO2, CO, NOx, O3, volatile organic compounds (VOCs), particulate matter (PM2.5 and PM10), and trace elements (TEs). Environmental and health risk indicators were calculated to estimate the impact of exposure to air pollution on nearby ecosystems and the population's health, respectively. The study revealed a low contribution of the WWTPs to the SO2, CO, and PM levels. However, WWTP1 showed an NOx annual average concentration close to the legislated threshold, and the target O3 value for the protection of human health was also exceeded. Regarding VOCs, the main contribution was the group of oxygenated aromatics. Concerning TEs, a high enrichment factor value was obtained for sodium, arsenic, selenium, potassium, nickel, copper, zinc, and lead at WWTP1 and for zinc, cadmium, copper, and selenium at WWTP2.

Improved Pavement Concrete Performance through Partial Cement Replacement with Fly Ash

With the rapid growth of industrial activities, a significant amount of waste materials is being generated, posing serious challenges in terms of environmental impact and land utilization for disposal. Among these industrial by-products, fly ash, produced during coal combustion in thermal power plants, has emerged as a potential resource for sustainable construction. This study explores the use of fly ash as a partial replacement for Ordinary Portland Cement (OPC) in Pavement Quality Concrete (PQC) to enhance both mechanical performance and environmental sustainability. Cement production is a major contributor to greenhouse gas emissions. As construction demand increases, so does the need for cement. To address this environmental concern, fly ash obtained from Godawari Power & Ispat Ltd. (GPIL), Raipur has been utilized in this study as a substitute for a portion of cement in the concrete mix. The objective is to assess its effectiveness in improving the strength characteristics of pavement concrete while promoting sustainable construction practices. Experimental investigations were carried out by partially replacing OPC with varying percentages of fly ash, along with the use of a polymer-based superplasticizer to achieve the desired workability and strength. Concrete samples were tested at curing periods of 3, 14, and 28 days. Results indicate that, without superplasticizer, the compressive strength of PQC is inadequate at early and later stages. However, the inclusion of a superplasticizer significantly enhances compressive strength, meeting the performance requirements. Flexural strength was found to be satisfactory even without a superplasticizer, and further improved with its use. This research confirms that partial replacement of cement with GPIL fly ash, in combination with suitable admixtures, can result in environmentally friendly and structurally efficient pavement concrete.

Health-environment. How to decarbonize our healthcare system: the case of the canton of Geneva

Although highly efficient, the Swiss healthcare system accounts for 6.7% of the country's greenhouse gas emissions. In Geneva, our study assessed its carbon footprint for the first time, estimating it at 436,831 tCO2e in 2022. Hospitals (47%) and medications (58.6%) are the main factors and sources of these emissions. Various scenarios, including health promotion and prevention, underscore the importance of direct and indirect measures to cut these emissions by 70% by 2040. These approaches are adaptable to other cantonal healthcare systems.

Potential and Challenges of Renewable Energy Management: Socio-economic Perspective in Indonesia

Renewable energy in Indonesia has great potential to reduce dependence on fossil fuels and combat climate change. Despite abundant resources such as solar, wind, and biomass, regulatory, infrastructure, and investment challenges still hamper its development. This study uses a qualitative approach to explore the state of renewable energy and its socio-economic impacts. The results and analysis show that renewable energy development can increase energy access, create jobs, and reduce greenhouse gas emissions. Collaboration between the government, private sector, and communities is essential for a successful transition. Recommendations include improving policies, increasing investment, and public education to ensure more equitable and sustainable benefits from renewable energy in Indonesia.

Synergizing crops and conservation: A comprehensive review of bio-intensive complementary cropping system

Cropping system represents a holistic approach to farming that emphasizes synergy among plant species, soil organisms and ecological processes. Exploring novel farming techniques has become essential in light of the growing environmental concerns and the increasing demands for sustainable agriculture. Bio-intensive complementary cropping offers promising strategy for a more sustainable and resilient future by integrating conservation agriculture practices. This approach diverges from traditional cropping systems by prioritizing productivity, resource optimization through complementary cropping, strategic resource management and ecological resilience. Key conservation methods include suitable crop intensification for optimum space use, irrigation strategies for minimizing water wastage, weed management for encouraging smothering effect and nutrient management that enhance the soil fertility by prioritizing organic inputs and local resource. By reducing pesticide use, enhancing biodiversity and lowering greenhouse gas emissions through reduced dependence on fossil fuel intensive inputs, bio-intensive systems contribute significantly to environmental sustainability. This review critically analyses soil health, crop productivity, emission profiles and economic outcomes, providing insights that advance scientific understanding and offer practical solutions for farmers. Ultimately, it highlights the potential of bio-intensive cropping systems to synergize crop production with conservation, paving the way for more sustainable agricultural practices.

Watershed hydrological response in developing climate change resilience and adaptation strategies, case of Gilgal Gibe watershed, Ethiopia.

Climate change is one of the most challenging and inevitable global environmental problems affecting mankind and its environment regardless of urban and rural areas. Its effect on watershed hydrology is challenging the sustainable water resources management and its availability across the globe. In order to develop a sustainable climate change adaptation strategy, understanding watershed hydrological response to the ever increasing climate change is highly important. Hence, the main objective of this study was investigating role of watershed hydrological response in developing climate resilience and adaptation strategy as a case study in Gilgal Gibe watershed,OmoGibe river basin, Ethiopia. To achieve the main objective of the study, three regional climate models (RCM) derived from one global climate model (GCM) under two greenhouse gas emission scenarios (RCP4.5 and RCP8.5) were collected from CORDEX Africa. The observed weather data and stream flow data were collected from National Meteorological Agency (NMA) and Ministry of Water and Energy (MoWE). The Climate data from CORDEX like maximum and minimum temperature, and precipitation were extracted using R-programming. These data were analyzed against the 1986-2016 baseline data and projected for near-future term (2020-2050) andmid-futureterm (2051-2080). The climate dataset trend analysis over the specified period was conducted using Mann-Kendall test, and the hydrological modeling was performed using the calibrated and validated HEC-HMS hydrological modeling tool. From the analysis, it was found that hydro-climate variability over the proposed time horizon was clearly observed from all RCM under both greenhouse gas emission scenarios. The stream flow revealed an oscillating trend over the course of the operation years under RCP4.5 and RCP8.5 greenhouse gas emission scenarios. Hence, this information is important for water resources manager, decision makers, practitioners and policy makers so as to enable them develop sustainable climate change resilience and adaptation strategies across the watershed.

Assessing the Level of Food Waste Awareness Among Senior High School Students at Mapúa University, Intramuros

Food waste has become a global crisis threatening environmental sustainability and food security. In the Philippines, households generate millions of tons of food waste annually, significantly contributing to greenhouse gas emissions. While studies exist on general waste management in educational settings, there is limited research examining food waste awareness among senior high school students in Philippines. This study aimed to evaluate the level of awareness concerning food waste among senior high school students at Mapúa University, Intramuros by assessing their awareness of food waste concepts, environmental, and social impacts, and analyzing awareness levels across demographic characteristics. Using descriptive quantitative, the study employed a survey questionnaire administered to 190 senior high school students selected through purposive sampling. The instrument measured awareness across four dimensions: food waste concepts, environmental impacts, social impacts, and demographic factors. Moreover, data were analyzed using descriptive statistics to identify patterns and relationships. The findings revealed that students possessed a solid conceptual understanding of food waste (mean = 4.10) and strong awareness of both environmental (mean = 4.15) and social impacts (mean = 4.24). Respondents have particularly high recognition of impacts on resource depletion, malnutrition, and community food access. Notable demographic patterns also emerged: female students (mean = 4.31-4.43) demonstrated higher awareness than males (mean = 3.91-4.05); awareness increased with age such as those in 18-20 years of age (mean = 4.16-4.29) and in Grade 12 (mean = 4.26-4.37); frequent users of campus food facilities showed heightened understanding (mean = 4.27-4.54); and participation in sustainability programs was associated with comprehensive awareness across all dimensions (mean = 4.28-4.41). This study provides insights for developing targeted educational programs and awareness campaigns at Mapúa University, potentially serving as a model for other Philippine educational institutions seeking to enhance food waste awareness and foster sustainable practices among students.

Halogen/Nitrogen Codoped Carbon Encapsulated Ni Nanoparticles for Efficient CO2 Electroreduction and High-Performance Zn-CO2 Batteries.

Electroreduction of CO2 (ECR) to CO or syngas is an effective approach to alleviating greenhouse gas emissions. Herein, nickel nanoparticles coated with halogen/nitrogen codoped carbon were prepared (X-Ni/NC-a). Cl-Ni/NC-a can obtain three important syngas compositions (CO:H2) under different voltages, such as 0.97, 0.51, and 0.32, which are the ratios for hydroformylation, methanol, and ethanol synthesis, respectively. For Br-Ni/NC-a, the CO Faraday efficiency (FEco) can exceed 96%, with a CO partial current density (jco) of 48 mA cm-2. Additionally, Br-Ni/NC-a is used in a Zn-CO2 battery (ZCB); the power density can reach 2.6 mW cm-2, and the charge-discharge stability can reach 110 h. DFT calculations revealed that the strong interaction between nickel nanoparticles and halogen/nitrogen codoped carbon regulates the electronic structure of the catalyst, affecting the adsorption/desorption of intermediates. This study provides a feasible scheme for halogen doping to modulate the selectivity of ECR and the potential application of catalysts in ZCB.

Экономическое обоснование новых технологических решений по лесовосстановлению гарей в центральной лесостепи Российской Федерации

In the presented study, we conducted a feasibility study of the costs of implementing new carbon-saving technological solutions for reforestation of burnt areas, ensuring accelerated and effective restoration of lands damaged by forest fires. An analysis of existing practices of reforestation on burnt areas allowed us to conclude that there are technological solutions that negatively affect the carbon balance, contributing to additional carbon emissions from the soil, when its structure is destroyed. This state of affairs predetermines the need to modernize existing forestry technologies in the direction of reducing emissions and increasing the absorption of greenhouse gases in order to solve the problems of low-carbon development of the country. New technological solutions for reforestation of burnt areas in the central forest-steppe of the Russian Federation were scientifically substantiated, for each phase of the work a scientific justification was given for the machine system, standard costs for the implementation of activities in order to achieve the indicators of the Strategy for the Socioeconomic Development of the Russian Federation with a low level of greenhouse gas emissions. It has been established that the modernization of technological solutions for forest reproduction in the place of burnt areas will be carried out by increasing the number of agricultural techniques and using high-performance and expensive equipment necessary to improve the survival rate of plants and preserve carbon in soils. It has been determined that the project carbon-saving technologies for creating forest crops on burnt areas are distinguished by a higher level of costs compared to the basic technology for creating plantations on forest fund lands. This circumstance will require adjustments to strategic forest planning documents and the attraction of additional funds.

Sustainable Corrosion Protection of Aluminium Alloys – Life Cycle Assessment of Established and Innovative Coating Processes

Aluminium alloys are highly valued for their lightweight properties. However, their susceptibility to corrosion, particularly in chloride-containing environments, presents significant challenges especially when considering "green" sustainable processing routes. Applying ISO 14040 life cycle assessment (LCA) approach, traditional surface treatment techniques (anodization, conversion coatings, organic paints, plasma activated chemical vapour deposition in vacuum) are compared for the first time to innovative approaches such as Atmospheric Pressure Plasma Deposition (APPD). Although highly conservative assumptions are taken in the life cycle inventory, the greenhouse gas emissions of APPD are clearly lower than in the other technologies, especially because of the higher efficiency in feedstock use, the higher throughput, and the plasma-and air-supported oxidation of CH4, formed during dissociation of the silicon organic precursor. By achieving corrosion properties of cerium-doped APPD silicone coatings similar to the state-of-the-art and elimination of repainting as for organic paints, APPD is at the forefront of sustainable processing.

Tracking air pollution and CO2 emissions in 13,189 urban areas worldwide using large geospatial datasets

Air pollution and climate change are urgent global concerns, with urban areas contributing heavily to both air pollutants and greenhouse gas emissions. Here we calculate fine particulate matter, nitrogen dioxide, and ozone concentrations and fossil-fuel carbon dioxide emissions per capita in 13,189 urban areas worldwide from 2005 to 2019 and analyze correlations between trends for these pollutants, leveraging recently-developed global datasets. Globally, we found significant increases in ozone (+6%) and small, non-significant changes in fine particulate matter (+0%), nitrogen dioxide (−1%), and fossil-fuel carbon dioxide emissions (+4%). Also, over 50% of urban areas showed positive correlations for all pollutant pairs, though results varied by global region. High-income countries with strong mitigation policies experienced decreases in all pollutants, while regions with rapid economic growth had overall increases. This study shows the impacts of urban environmental initiatives in different regions and provides insights for reducing air pollution and carbon dioxide emissions simultaneously.

Seasonal variations in net ecosystem exchange of CO2 and conservation of water use efficiency of cotton in the Mississippi Delta

AbstractAccurately quantifying the net ecosystem exchange (NEE) of CO2 is a critical prerequisite for developing alternative farm management strategies to enhance carbon sequestration in biological systems and reduce greenhouse gas emissions. A 2‐year study quantified the NEE of CO2 from cotton (Gossypium hirsutum L.) on silty clay in farm‐scale fields using an eddy covariance approach. On a seasonal scale, NEE and evapotranspiration were 8836 kg CO2 ha−1 and 367 mm, respectively, in 2017, and 10,759 kg CO2 ha−1 and 430 mm in 2018. Harvested cotton lint yields were 1269 and 1569 kg ha−1 in 2017 and 2018, respectively. The water use efficiency (WUE) for lint production (WUElint) and ecosystem level WUE for NEE (WUENEE) across the two seasons was nearly constant. WUElint was 3.5 and 3.6 kg lint ha−1 mm−1, respectively, in 2017 and 2018, and WUENEE was 24 and 25 kg CO2 ha−1 mm−1. The NEE and WUE measured in this study can be used as a benchmark for comparing carbon sequestration potential in cotton production. However, further research is needed to understand NEE responses to long‐term climate variability and to develop climate‐smart crop‐soil management strategies.

Technical Validation of Oil Production Greenhouse Gas Emissions Estimator Using Field Data from Thermal Enhanced Oil Recovery Operations

Technical Validation of Oil Production Greenhouse Gas Emissions Estimator Using Field Data from Thermal Enhanced Oil Recovery Operations

Sustainable microgrid system for Easter Island with the least cost and GHG emission‐free approach

AbstractThe prime focus of this research work is to design a microgrid hybrid system that is suitable for remote locations to supply power with less greenhouse gas (GHG) emission. This research focuses on electrifying remote locations with renewable energies with reduced GHG emission. Easter Island is more than 3500 km from the mainland and relies entirely on diesel generators for electricity. The diesel generator emits more emissions for supplying power to Easter Island, which will affect the environment. The alternative solution is identified by implementing renewable sources such as solar, wind, and tidal power in Easter Island. The sensitivity and optimization results are performed for Easter Island using HOMER software. The monthly average solar irradiation and wind speed are downloaded from the NREL database. The original load power for Easter Island is considered in this research work to determine the suitable power sources with less GHG emission. The results show that the solar/DG/tidal mix is suitable for Easter Island, with life cycle cost and energy cost at $22,816,140 and $0.147, respectively. The results also show that the GHG emission is 93.53% less when comparing the solar/DG/tidal hybrid system with the system consisting of a diesel generator alone. The result of the sensitivity analysis illustrates that there is an impact on varying maximum limits on CO2 emission, solar cell temperature, solar temperature coefficient of power, discount rate, and inflation rate. The change in load demand and solar degradation for multiple‐year variations is also analyzed.

Advancing synergistic strategies for greenhouse gas and atmospheric pollutant emission reduction in urban transportation: a whole lifecycle perspective

In light of the interrelated origins and processes of greenhouse gas (GHG) and atmospheric pollutant emissions, countries around the world are actively seeking synergistic strategies for their reduction. Urban transportation represents a critical sector for GHG and air pollutant emissions; however, the effectiveness of existing collaborative measures has proven inadequate. This ineffectiveness primarily stems from a focus on terminal emission reductions, neglecting potential pollutant emissions that arise during implementation. To address this gap, this paper develops seven scenarios for coordinated emission reductions in urban transportation and employs econometric methods to quantitatively assess the effectiveness of these strategies throughout their entire lifecycle. Furthermore, the evaluation integrates key indicators, such as synergistic emission reduction, a coordinated control system, and cross-elasticity, to provide a comprehensive analysis of the proposed measures. This paper uses Shenyang, China, as a case study, revealing that enhancing fuel quality emerges as the most critical strategy for synergistic emission reduction. Although the comprehensive synergistic emission reductions associated with rail transit and low-carbon travel are not the highest, they demonstrate a significant linkage effect. Although the promotion of new energy vehicles (NEVs) offers substantial terminal emission reductions, their energy generation processes and consumption during charging classify them as non-synergistic measures. This study addresses the prevalent issue of overemphasizing terminal governance, providing valuable insights for policymakers in the urban transportation sector. It facilitates a deeper understanding of the synergistic control characteristics of various measures, enabling the identification of effective strategies and the exploration of their interconnections.

Urban and non-urban contributions to the social cost of carbon

The social cost of carbon (SCC) serves as a concise measure of climate change’s economic impact, often reported at the global and country level. SCC values tend to be disproportionately high for less-developed, populous countries. Previous studies do not distinguish between urban and non-urban areas and ignore the synergies between local and global warming. High exposure and concurrent socioenvironmental problems exacerbate climate change risks in cities. Using a spatially explicit integrated assessment model, the SCC is estimated at USD$187/tCO2, rising to USD$490/tCO2 when including urban heat island (UHI) warming. Urban SCC dominates, representing about 78%-93% of the global SCC, due to both urban exposure and the UHI. This finding implies that the highest global greenhouse gases (GHGs) emitters also experience the largest economic losses. Global cities have substantial leverage on climate policy at the national and global scales and strong incentives for a swift transition to a low-carbon economy.

Supplementing Hermetia illucens diet with minerals: effects on production performance, proximate composition and nitrogen loss

Abstract Black soldier fly (BSF, Hermetia illucens) farming is an emerging industry and the nutritional requirements of the larvae still remain unclear. In particular, the larval needs in micronutrients, such as minerals, are poorly understood although they play a critical role in insect physiology. Thus, we investigated whether supplementing BSF diet with polyhalite (K2MgCa2(SO4)4 ⋅ 2H2O), a pure mineral source, could improve the production performance traits of the larvae. Once hatched, the larvae were fed a single nursery diet until the fifth day post-hatch, then transferred to the experimental diets and harvested on the tenth day post-hatch. The control diet was made of brewery by-products, which are commonly used at industrial level in BSF farming, and rich in protein (38.1% of dry matter). On this basis, three others were designed to include 0.5, 1.0 and 1.5% of polyhalite. Larval survival, growth, feed conversion ratio (FCR) and yield were estimated, in addition to the feeding substrate reduction. Moreover, the larvae and diets had their nitrogen content determined to estimate the nitrogen loss for each diet. The proximate and amino-acid compositions of the larvae were also analysed. Larval survival was around 100% for all diets. For all the diets containing polyhalite, the growth, FCR, yield and substrate reduction were significantly improved compared to the control diet. However, 0.5% of polyhalite resulted in significantly better growth, FCR and yield than 1.5%, with 1.0% being intermediate. A decrease in nitrogen loss proportional to polyhalite inclusion was estimated, from 6.9% (0.5% of polyhalite) to a 27.4% decrease (1.5% of polyhalite). No clear variation appeared in the larval composition but for the ash content that increased with the inclusion rate of polyhalite. Mineral supplementation produced encouraging results in our study but requires further investigation, especially regarding its impact on the nitrogen gaseous emissions and larvae meal quality.