Carbon Dioxide Emission Rates Research Articles

Impacts of wind erosion and seasonal changes on soil carbon dioxide emission in southwestern Iran

Wind erosion is one of the main drivers of soil loss in the world, which affects 20 million hectare land of Iran. Besides the soil loss, wind erosion contributes to carbon dioxide emission from the soil into the atmosphere. The objective of this study is to evaluate monthly and seasonal changes in carbon dioxide emission in four classes i.e., low, moderate, severe and very severe soil erosion and the interactions between air temperature and wind erosion in relation to carbon dioxide emission in the Bordekhun region, Boushehr Province, southwestern Iran. Wind erosion intensities were evaluated using IRIFR (Iran Research Institute of Forests and Ranges) model, in which four classes of soil erosion were identified. Afterward, we measured carbon dioxide emission on a monthly basis and for a period of one year using alkali traps in each class of soil erosion. Data on emission levels and erosion classes were analyzed as a factorial experiment in a completely randomized design with twelve replications in each treatment. The highest rate of emission occurred in July (4.490 g CO2/(m2·d)) in severely eroded lands and the least in January (0.086 g CO2/(m2·d)) in low eroded lands. Therefore, it is resulted that increasing erosion intensity causes an increase in soil carbon dioxide emission rate at severe erosion intensity. Moreover, the maximum amount of carbon dioxide emission happened in summer and the minimum in winter. Soil carbon dioxide emission was just related to air temperature without any relationship with soil moisture content; since changes of soil moisture in the wet and dry seasons were not high enough to affect soil microorganisms and respiration in dry areas. In general, there are complex and multiple relationships between various factors associated with soil erosion and carbon dioxide emission. Global warming causes events that lead to more erosion, which in turn increases greenhouse gas emission, and rising greenhouse gases will cause more global warming. The result of this study demonstrated the synergistic effect of wind erosion and global climate warming towards carbon dioxide emission into the atmosphere.

Geospatial Variation of Real-World Tailpipe Emission Rates for Light-Duty Gasoline Vehicles.

Spatial variability in real-world on-road tailpipe light-duty gasoline vehicle nitrogen oxides, hydrocarbon, carbon monoxide, and carbon dioxide emission rates, the locations of emissions hotspots, and factors that explain spatial variability are quantified. A sample of 205 vehicles were measured on four predefined round-trip study routes using Portable Emission Measurement Systems. The trips on each route were divided into segments, averaging 1/4 mile in length. Segment-average emission rates were estimated based on measured 1 Hz emission rates. Emission hotspots are defined as segments with ≥90th percentile of segment-average emission rates. The hotspots have average emission rates 2-4 times greater, depending on the pollutant, than other segments. Hotspots are of heterogeneous characteristics including road attributes and vehicle activity metrics. For example, some hotspots were on arterial roads with an upstream signalized intersection and positive road grade, whereas some hotspots were on interstates with positive grade. Vehicle activity metrics, including average vehicle specific power and relative positive acceleration, help identify the hotspots. To reliably identify a fleet-average hotspot, data are needed for at least 36-130 vehicles, depending on the pollutant.

Energy-Aware Marine Predators Algorithm for Task Scheduling in IoT-Based Fog Computing Applications

To improve the quality of service (QoS) needed by several applications areas, the Internet of Things (IoT) tasks are offloaded into the fog computing instead of the cloud. However, the availability of ongoing energy heads for fog computing servers is one of the constraints for IoT applications because transmitting the huge quantity of the data generated using IoT devices will produce network bandwidth overhead and slow down the responsive time of the statements analyzed. In this article, an energy-aware model basis on the marine predators algorithm (MPA) is proposed for tackling the task scheduling in fog computing (TSFC) to improve the QoSs required by users. In addition to the standard MPA, we proposed the other two versions. The first version is called modified MPA (MMPA), which will modify MPA to improve their exploitation capability by using the last updated positions instead of the last best one. The second one will improve MMPA by the ranking strategy based reinitialization and mutation toward the best, in addition to reinitializing, the half population randomly after a predefined number of iterations to get rid of local optima and mutated the last half toward the best-so-far solution. Accordingly, MPA is proposed to solve the continuous one, whereas the TSFC is considered a discrete one, so the normalization and scaling phase will be used to convert the standard MPA into a discrete one. The three versions are proposed with some other metaheuristic algorithms and genetic algorithms based on various performance metrics such as energy consumption, makespan, flow time, and carbon dioxide emission rate. The improved MMPA could outperform all the other algorithms and the other two versions.

Effects of intermittent aeration on greenhouse gas emissions and bacterial community succession during large-scale membrane-covered aerobic composting

In order to study the effects of intermittent aeration on greenhouse gas emissions and bacterial community succession during membrane-covered aerobic composting, a large-scale aerobic composting experiment was carried out. Two different aeration intervals designed to maintain the temperature of the compost was in 50–65 °C. The control group and experimental group were set to 10 min–10 min (on-off) and 10 min–30 min (on-off), respectively. The results indicated that the emissions of methane and nitrous oxide from the outside of the membrane in the control group were 9.68% and 47.10% less than those in the experimental group. And the global warming potential was 9.77% less than that in the experimental group. Wilcoxon rank-sum test result indicated that Tenericutes was a significantly different phylum between the two groups and played an important role in cellulose degradation. Redundancy analysis indicated that C/N had the greatest influence on the distribution of the bacterial community. It also found that Pseudogracilibacillus and Tepidimicrobium were significantly correlated with nitrous oxide and carbon dioxide emission rates, respectively. Therefore, adjusting aeration interval time during the membrane-covered aerobic composting could be a useful strategy for limiting greenhouse gas emissions and effecting bacterial community structure.

Estimating the feasibility of using industrial solid wastes as raw material for polyurethane composites with low fire hazards

Solid wastes including phosphate tailings (PT) and fly ash (FA) are by-products with large quantities and deposited in surface impoundment without treatment, which can easily trigger environment issues. The comprehensive utilization of industrial solid wastes has received intensive attention. In present work, the recycling of industrial solid wastes was studied to explore the probability of utilizing PT and FA as fillers for fabrication of polymer materials with low fire hazards. The micro-sized PT and FA powders were firstly treated with silane coupling agents and then introduced into thermoplastic polyurethane (TPU) through solvent blending method. The influences of solid wastes on the thermal degradation behavior, as well as the fire hazards of TPU were explored. The thermogravimetric analysis results illustrated that due to the introduction of PT and FA, the thermal degradation rate was reduced while the thermal degradation temperature and char yields were increased, in contrast to pristine TPU. The cone calorimetry test results demonstrated the introduction of PT and FA obviously reduced the heat release rate (HRR), total heat release (THR), smoke production rate (SPR), total smoke release (TSR), carbon monoxide (CO) and carbon dioxide (CO2) emission rate of TPU composites. Therefore, the PT and FA might be promising fillers for fabrication of polymeric materials with controllable properties and provide a novel solution for effective recycling of industrial solid wastes.

Energy-Aware Metaheuristic Algorithm for Industrial-Internet-of-Things Task Scheduling Problems in Fog Computing Applications

In Industrial-Internet-of-Things (IIoT) applications, fog computing (FC) has soared as a means to improve the Quality of Services (QoSs) provided to users through cloud computing, which has become overwhelmed by the massive flow of data. Transmitting all these amounts of data to the cloud and coming back with a response can cause high latency and requires high network bandwidth. The availability of sustainable energy sources for FC servers is one of the difficulties that the service providers can face in IIoT applications. The most important factor contributing to energy consumption on fog servers is task scheduling. In this article, we suggest an energy-aware metaheuristic algorithm based on a Harris Hawks optimization algorithm based on a local search strategy (HHOLS) for task scheduling in FC (TSFC) to improve the QoSs provided to the users in IIoT applications. First, we describe the high virtualized layered FC model taking into account its heterogeneous architecture. The normalization and scaling phase aids the standard Harris hawks algorithm to solve the TSFC, which is discrete. Moreover, the swap mutation ameliorates the quality of the solutions due to its ability to balance the workloads among all virtual machines. For further improvements, a local search strategy is integrated with HHOLS. We compare HHOLS with other metaheuristics using various performance metrics, such as energy consumption, makespan, cost, flow time, and emission rate of carbon dioxide. The proposed algorithm gives superior results in comparison with other algorithms.

Methane and Carbon Dioxide Emission of Beef Heifers in Relation with Growth and Feed Efficiency.

Simple SummaryFor sustainable meat production, beef farmers must make the best use of grass and roughage while limiting the carbon footprint of their herds. The genetic improvement in feed efficiency and enteric methane production of replacement heifers is possible if the recorded phenotypes are available. Intuitively, the relationship between the two traits should be negative, i.e., favorable, since the energy lost with the methane is not available for heifer metabolism. The measurement of feed efficiency requires several weeks of feed intake recording. The enteric methane emission rate can also be recorded over several weeks. The two traits of 326 beef heifers from two experimental farms were measured simultaneously for 8 to 12 weeks. The correlations between roughage intake, daily gain, and methane were all positive. The enteric methane emission rate was positively related to body weight, daily gain, and dry matter intake. The relationship with feed efficiency was slightly positive, i.e., unfavorable. Therefore, the two traits should be recorded simultaneously to evidence low-emitting and efficient heifers. This study also showed that replacing the feed intake recording with the carbon dioxide emission rate appeared potentially beneficial for selecting these low-emitting and efficient heifers.Reducing enteric methane production and improving the feed efficiency of heifers on roughage diets are important selection objectives for sustainable beef production. The objective of the current study was to assess the relationship between different methane production and feed efficiency criteria of beef heifers fed ad libitum roughage diets. A total of 326 Charolais heifers aged 22 months were controlled in two farms and fed either a grass silage (n = 252) or a natural meadow hay (n = 74) diet. Methane (CH4) and carbon dioxide (CO2) emission rates (g/day) were measured with GreenFeed systems. The dry matter intake (DMI), average daily gain (ADG), CH4 and CO2 were measured over 8 to 12 weeks. Positive correlations were observed among body weight, DMI, ADG, CH4 and CO2. The residual feed intake (rwgDMI) was not related to CH4 or residual methane (rwiCH4). It was negatively correlated with methane yield (CH4/DMI): Rp = −0.87 and −0.83. Residual gain (rwiADG) and ADG/DMI were weakly and positively related to residual methane (rwiCH4): Rp = 0.21 on average. The ratio ADG/CO2 appeared to be a useful proxy of ADG/DMI (Rp = 0.64 and 0.97) and CH4/CO2 a proxy of methane yield (Rp = 0.24 and 0.33) for selecting low-emitting and efficient heifers.

Are internally observable vehicle data good predictors of vehicle emissions?

Scientific research has demonstrated that on-road exhaust emissions in diesel passenger vehicles (DPV) exceeds the official laboratory-test values. Increasing concern about the quantification of magnitude for these differences has meant an increasing use of Portable Emissions Monitoring System (PEMS), but the direct use of Internally Observable Variables (IOVs) can be useful to predict emissions.The motivation for this paper is to develop an empirical approach that integrates second-by-second vehicle activity and emission rates for DPV. The objectives of this research are two-fold: (1) to assess the effect of variation in acceleration-based parameters, vehicle specific power (VSP) and IOVs on carbon dioxide (CO2) and nitrogen oxides (NOx) emission rates; and (2) to examine the correlation between IOV-based predictors of engine load and VSP. Field measurements were collected from four DPV (two small, one medium and one multi-purpose) in urban, rural and highway routes using PEMS, Global Positioning System (GPS) receivers and On-board Diagnostic (OBD) scan tool, to measure real-world exhaust emissions and engine activity data.Results suggest the relative positive acceleration (RPA) and mean positive acceleration (MPA) allowed a good differentiation with respect to route trips. IOVs models based on the product of manifold absolute pressure (MAP) and engine revolutions per minute (RPM), and VSP showed to be good predictors of emission rates. Although the CO2 correlation was found to be good (R2 > 0.8), the models for NOx showed mixed results since some vehicles showed a reasonable correlation (R2 ~ 0.7) while others resulted in worst model predictions (R2 < 0.6).IOVs models have potential to be integrated into vehicle engine units and connected vehicles, for instance, to provide real-time information on emissions rates, but other parameters regarding the thermal management on after treatment system must be included in NOx prediction. This would allow for a better understanding of true physics behind NOx emissions in DPV.

Thermodynamic, exergoeconomic, and environmental evaluation of a new multi-generation system driven by a molten carbonate fuel cell for production of cooling, heating, electricity, and freshwater

Because of the ever-growing demand for energy in today’s world, new efficient multi-generation systems are much sought after. Analyzing the practicality and performance of such innovative systems, especially ones utilizing novel energy conversion technologies, has been a popular subject among scientists. In this paper, a comprehensive assessment of a novel multi-generation system driven by a molten carbonate fuel cell is presented from thermodynamic, exergoeconomic, and environmental viewpoints. The proposed system consists of a molten carbonate fuel cell for electricity generation, a heating process heat exchanger for superheated steam generation, a generator-absorber heat exchanger cycle for generating cooling load, and a desalination subsystem for producing freshwater. To investigate the performance of the system, the influences of two important parameters, namely current density and fuel cell operating temperature, are studied on the generated cell voltage as well as the production rates of the products, the energy and exergy efficiencies, the cost rate, the cost per unit exergy, and the carbon dioxide emission rate. According to the results, the net electrical power production and the energy and exergy efficiencies of the proposed system are 1439 kW, 79.9%, and 51.9%, respectively. Also, the investment cost rate of the system is 30.4 $/h, which results in the production of the mentioned outputs with a total cost per unit exergy of 21.6 $/GJ. Moreover, the carbon dioxide emission rate of the system is found to be 247 kg/MWh.

Particulate matter-attributable mortality and relationships with carbon dioxide in 250 urban areas worldwide

Urban air pollution is high on global health and sustainability agendas, but information is limited on associated city-level disease burdens. We estimated fine particulate matter (PM2.5) mortality in the 250 most populous cities worldwide using PM2.5 concentrations, population, disease rates, and concentration-response relationships from the Global Burden of Disease 2016 Study. Only 8% of these cities had population-weighted mean concentrations below the World Health Organization guideline for annual average PM2.5. City-level PM2.5-attributable mortality rates ranged from 13–125 deaths per 100,000 people. PM2.5 mortality rates and carbon dioxide (CO2) emission rates were weakly positively correlated, with regional influences apparent from clustering of cities within each region. Across 82 cities globally, PM2.5 concentrations and mortality rates were negatively associated with city gross domestic product (GDP) per capita, but we found no relationship between GDP per capita and CO2 emissions rates. While results provide only a cross-sectional snapshot of cities worldwide, they point to opportunities for cities to realize climate, air quality, and health co-benefits through low-carbon development. Future work should examine drivers of the relationships (e.g. development stage, fuel mix for electricity generation and transportation, sector-specific PM2.5 and CO2 emissions) uncovered here and explore uncertainties to test the robustness of our conclusions.

Mitigation of ruminal biogases production from goats using Moringa oleifera extract and live yeast culture for a cleaner agriculture environment

The present investigation was assessed to explore the sustainable mitigation of methane and carbon dioxide production from goats using Moringa oleifera extract and live yeast culture (Saccharomyces cerevisiae) as feed supplements. Treatments include supplementation of 0 (control), 0.6, and 1.8 mL/g dry matter of M. oleifera extract and 0 (control), 2, and 4 mg/g dry matter of commercially available S. cerevisiae into the feeding diet. Higher doses of M. oleifera extract and S. cerevisiae increased the asymptotic gas production from 88.8 to 147.5 mL/g dry matter. The fractional rate of gas production was increased (P < 0.05) due to the supplementation of M. oleifera extract and S. cerevisiae. Lag time increased linearly from 1.32 to 3.99 h but only M. oleifera extract affected it quadratically (P = 0.041). The asymptotic methane production, rate of methane emission, and lag time decreased (P > 0.05) with the varied doses of additives. M. oleifera extract × S. cerevisiae interaction had non-significant (P > 0.05) influence on asymptotic carbon dioxide emission, fractional rate of carbon dioxide emission, and lag time. Furthermore, the inclusion of S. cerevisiae exhibited increased gas production in a time dependent manner. The proportional methane production was estimated to be decreased (P > 0.05) at high doses of M. oleifera extract and S. cerevisiae at 72 h of incubation with the lowest emission of 11.7%. In contrary to this, the proportional carbon dioxide production was reduced (quadratic effect, P = 0.031) at 72 h of incubation with the lowest emission of 50.3%. In conclusion, the addition of M. oleifera extract and S. cerevisiae in diets would be an invaluable approach for mitigating methane and carbon dioxide emission from goats. These additives at diversified concentrations may be utilized as pronounced cleaner product and additive agents for the ecosystem as well as livestock.

CO2-induced asphaltene deposition and wettability alteration on a pore interior surface

CO2 enhanced oil recovery has a great potential to improve the rate of oil production and store carbon dioxide emission. However, CO2 injection can destabilize the asphaltene-oil colloidal system and thus favor severe asphaltene particle deposition in porous reservoir formation. These block reservoir pores and change pore wetting condition, finally damage the porous reservoir formation and significantly reduce oil production. A good understanding on CO2-induced asphaltene deposition at a pore scale is of significance for CO2-EOR processes. Few studies have directly investigated the asphaltene deposition behavior and asphaltene-induced pore wetting alteration on a pore interior surface in a confined pore. In this study, we directly measured the CO2-induced asphaltene deposition behavior on the interior surface of a single pore under high pressure and temperature. The particle size and particle size distribution of CO2-induced asphaltene deposition on pore interior surfaces were directly measured and analyzed, by considering the influences of aging time and temperature. The results indicate that long aging period and elevated temperature could favor CO2-induced asphaltene flocculation and deposition on pore interior surfaces. Finally, the pore-scale wetting alteration caused by asphaltene deposition was quantified by direct pore contact angle measurements.

Environmental pollution cost analyses of biodiesel and diesel fuels for a diesel engine

In this study, Japanese Industrial Standard diesel no 2 and waste cooking oil biodiesel fuels are compared in terms of environmental pollution cost analysis. The experiments of the diesel and biodiesel fueled diesel engine are done at 100 Nm, 200 Nm and full load (294 Nm), while engine speed is constant at 1800 rpm. The method used in this study consists of a combination of economic and environmental parameters. According to the analyses, the total environmental pollution cost of the biodiesel is higher than the diesel fuel. On the other hand, the total cost of the CO2 emissions of the diesel fuel is generally found to be higher than biodiesel fuel in terms of the life cycle based environmental pollution cost. The specific environmental pollution cost is found as minimum at full load to be 2.217 US cent/kWh for the diesel fuel and 2.449 US cent/kWh for the biodiesel fuel at full load. On the other hand, the life cycle based specific environmental pollution cost is determined as minimum at full load to be 5.050 US cent/kWh for the diesel fuel and 5.309 US cent/kWh for the biodiesel fuel. The biodiesel fuel has higher values than diesel fuel in terms of the specific environmental pollution cost rates. The maximum total carbon dioxide emission rate is found as 0.2405 × 10−3 kg/kJ for the biodiesel fuel at 100 Nm engine torque and the minimum one is obtained as 0.1884 × 10−3 kg/kJ for the diesel fuel at full load. When the payback periods of the fuels are examined, biodiesel has longer period than diesel. The environmental payback period and life cycle based environmental payback period are also compared for fuels. In this context, the biodiesel has longer environmental payback periods rates than diesel. Consequently, the biodiesel fueled engine has higher environmental pollution cost rates than the diesel fueled engine, while the total carbon dioxide parameter of the diesel fuel is close to the biodiesel fuel's rate. Also, all of the other environmental parameters of diesel fuel is generally better than biodiesel. Consequently, the diesel fuel is generally better option than the biodiesel considering environmental aspects. For better environmental management, the diesel fuel utilization in the diesel engine is slightly better option than biodiesel fuel in terms of environmental pollution cost analysis.

Biodegradation of tannery dye effluent using Fenton's reagent and bacterial consortium: A biocalorimetric investigation

The impact caused by dye effluent discharge on the environment is well known. The study explores a hybrid method of combining Fenton oxidation with biological treatment by a defined bacterial consortium for the biodegradation of an effluent containing toxic azo dye (acid blue 113). In actual treatment process, the fluctuation in toxic load and presence of other dyeing chemical inhibits the activity of the bacterial consortium. An effective pre-treatment of effluent would ensure the optimal degradation irrespective of its initial load. The pre-treatment of dye effluent with Fenton (H2O2 & Fe2+), considerably reduced the dye concentration by 40% and a maximum dye degradation of 85% (i.e., 45% by biodegradation) was achieved in shake flask. The biodegradation process was investigated in a bioreaction calorimeter (BioRc1e), the heat profile, bioenergetics data along with CER (Carbon dioxide emission rate) and OUR (Oxygen uptake rate) provided vital information for the effective commercial scale up. Enhanced degradation of up to 97% was achieved in BioRc1, the CER and OUR profile follows the power-time profile alluding that the heat generated is the resultant effect of bacterial metabolic activity. In real dye bath effluent the Fenton pre-oxidized biodegradation reaction showed a degradation efficacy of 89.5% and considerable COD reduction of 93.7%. Fluorescence-activated cell sorting (FACS) analysis revealed a better bacterial cell proliferation in pre-treated experiment and gas chromatography and mass spectrum analysis were used for prediction of metabolites. The unique combination of Fenton and the microbial consortia is a competitive technology for industrial effluent treatment processes.

Hybrid Systems Optimization: Application to Hybrid Systems Photovoltaic Connected to Grid. A Mali Case Study

Access to electricity and supplying reliable energy are the key elements that support local economic development and contribute to reducing poverty. Moreover, the problem of environmental protection can be considered as a factor of sustainable development. In response to these many challenges, appropriate national and regional policies, as well as mechanisms, have been implemented. In Mali, strong dependence on the importation of oil, growth in demand, and the low rate of electrification have pushed the highest authorities to think of diversified technological solutions like renewable energy for the satisfaction of energy demands, especially photovoltaics, for which the country has significant potential. The hybrid systems used is a compromise, because the emission rate of carbon dioxide emitted by thermal power plants must be reduced and limited to preserve supernatural disasters. For this, hybrid photovoltaic systems coupled to the grid increased, but the management of the production of these photovoltaics poses a lot of problem due to its intermittent status. It is in this context that we conducted an optimization study of a hybrid system photovoltaic connected to the grid. We applied our approach to the most extensive distribution post of Mali capital. For the simulation, we used the modeling and simulation tool named HOMER.

Comparison of real-world vehicle fuel use and tailpipe emissions for gasoline-ethanol fuel blends

Differences in fuel use and emission rates of carbon dioxide (CO2), carbon monoxide (CO), hydrocarbons (HC), nitrogen oxide (NOx), and particulate matter (PM) were quantified for three gasoline-ethanol blends and neat gasoline measured for one flexible-fuel vehicle (FFV) and four non-FFVs using a portable emission measurement system (PEMS). The purpose was to determine if non-FFVs can adapt to a mid-level blend and to compare the fuel use and emission rates among the fuels. Each vehicle was measured on neat gasoline (E0), 10% ethanol by volume (E10) “regular” (E10R) and “premium” (E10P), and 27% ethanol by volume (E27). Four real-world cycles were repeated for each vehicle with each fuel. Second-by-second fuel use and emission rates were binned into Vehicle Specific Power (VSP) modes. The modes were weighted according to real-world standard driving cycles. All vehicles, including the non-FFVs, were able to adapt to E27. Octane-induced efficiency gain was observed for higher octane fuels (E10P and E27) versus lower octane fuels (E0 and E10R). E27 tends to lower PM emission rates compared to E10R and E10P and CO emission rates compared to the other three fuels. HC emission rates for E27 were comparable to those of E10R and E10P. No significant difference was found in NOx emission rates for E27 versus the other fuels. Intervehicle variability in fuel use and emission rates was observed. Lessons learned regarding study design, vehicle selection, and sample size, and their implications are discussed.

Carbon monoxide and carbon dioxide emission rates from various coffee bean roasts

Carbon monoxide and carbon dioxide emission rates from various coffee bean roasts

Change in straw decomposition rate and soil microbial community composition after straw addition in different long-term fertilization soils

Fertilization practices can change soil fertility and biological properties, and influence its ecological functions. We studied the change in the straw decomposition rate and microbial community composition in soils with different long-term fertilization regimes (no-fertilizer control (CK); nitrogen, phosphorus, and potassium fertilizers (NPK); and NPK plus straw (NPKS)) with addition of straw in a 75-day incubation experiment. Carbon dioxide (CO2) emission rates from the straw material were 13.9, 15.8, and 17.9 μg C g−1 soil day−1 in the CK + S, NPK + S, and NPKS + S treatments, respectively. After straw addition, the biomass of fungi and bacteria increase following the order of CK + S ≤ NPK + S < NPKS + S; while the bacterial richness decreased and did not change with incubation time, the fungal richness decreased and presented different responses among treatments with incubation time. Their diversities presented a decreasing-increasing trend with incubation time in all treatments. The richness and diversity of bacteria and fungi were positively correlated with soil NO3−–N. Bacterial community structure on days 1 and 3 were significantly separated from that on day 75; however, fungal community structure did not differ significantly as that of bacteria across different stages in the same treatment. A redundancy analysis showed that straw addition changed the community structure of bacteria and fungi by decreasing soil NO3−–N, and their community structures were regulated by soil organic C in the early stage and by NH4+–N in the later incubation stage. The relative abundance of the bacterial phyla Proteobacteria, Firmicutes, and fungal phyla Ascomycota showed synchronized changes with straw CO2 emissions rate. Our findings suggested that long-term fertilization and the return of straw to soils increased straw decomposition relative to the unfertilized soil, the latter difference in decomposition attributed to greater biomass of bacteria and fungi resulting from the improvement in soil fertility.

Inventory of kiln stacks emissions and health risk assessment: Case of a cement industry in Southwest Nigeria

Cement production is a significant source of air pollution as both gaseous and particulate materials released are detrimental to the ecosystem. This work was carried out in a cement industry located in Southwest Nigeria. The emission rates of carbon monoxide (CO), nitrogen oxides (NOx), carbon dioxide (CO2) and sulphur oxides (SOx) released from the cement kilns using fuel oil, natural gas (NG) and coal were garnered for a year. Thereafter, the estimated emission quantities of the pollutants were employed to obtain the emission inventory of the cement plant. Uncertainty analysis associated with the emissions was evaluated using Analytica® (4.6). Total amounts of pollutants emitted from the plant were 4.86 tonne (t) (NOx), 18.2 t (SOx), 2.270 Kt (CO2) and 1.17 t (CO). Uncertainty range of –149.38% to 149.38% was connected to all the pollutants. Results showed that the quantities of pollutants discharged from the cement industry were considerably higher than recommended. The evaluated air quality indices for CO, NOx, and SOx implied that the health risk on exposure to these gases was hazardous. This study revealed that NG and wastes are the best fuel for kiln firing to reduce the amounts of pollutants emitted into the microenvironment of the plant.

Effect of magnesium sulphate addition to broiler litter on the ammonia, nitrous oxide, carbon dioxide and methane emissions from housing

Poultry production is a significant source of gaseous emissions and will require economical and simple mitigation techniques that can be used by farmers. The aim of the present study was to assess the influence of magnesium sulphate (MgSO4.7H2O) addition to broiler litter on ammonia (NH3), nitrous oxide (N2O), carbon dioxide (CO2) and methane (CH4) emission rates from housing under Mediterranean climate conditions. Two identical broiler houses located in a Portuguese commercial farm were used for this study: one house was a control and the other was treated with magnesium sulphate as litter additive. Data were collected during two fattening cycles of a whole year; first in the cold season (11.8 ± 1.9 °C) and second in the hot season (20.4 ± 1.0 °C). Results showed that the application of magnesium sulphate was a good mitigation technique to reduce NH3 and N2O emissions from broiler houses. The annual average emission rates of untreated house were reduced (p < 0.05) by 45% for NH3 and 25% for N2O by the application of magnesium sulphate whereas CO2 and CH4 emission rates were increased (p < 0.05) in about 20%. Furthermore, the global warming potential was increased (p < 0.05) till 20% by the litter additive.