The variation of greenhouse gas emissions from soils of various land-use/cover types in Jambi province,Indonesia

We measured fluxes of three greenhouse gases (N₂O, CO₂O and CH₄) from soils of six different land-use types at 27 temporary field sites in Jambi Province, Sumatra, Indonesia. Study sites included natural and logged-over forests; rubber plantation; oil palm plantation; cinnamon plantation; and grassland field. The ranges of N₂O, CO₂ and CH₄ fluxes were 0.13–55.8 gN m-2h-1; 1.38–5.16 g C m-2d-1; –1.27–1.18 mg C m-2d-1, respectively. The averages of N₂O, CO₂ and CH₄ fluxes at 27 sites were 9.4 gN m-2h-1,3.65 g C m-2d-1, –0.45 mg C m-2d-1, respectively. The values of CO₂ and CH₄ fluxes were comparable with those in the reports regarding other humid tropical forests, while the N₂O flux was relatively lower than those of previous reports. The N₂O fluxes in each soil type were correlated with the nitrification rates of soils of 0–5 cm depth. In Andisols, the ratio of the N₂O emission rate to the nitrification rate was possibly smaller than that of the other soil types. There was no clear relationship between N₂O flux and the soil water condition, such as water-filled pore space. Seventeen percent of CH₄ fluxes were positive; according to these positive fluxes, we did not find a good correlation between CH₄ uptake rate and soil properties. Although we performed a chronosequence analysis to produce some hypotheses about the effect of land-use change by a limited amount of sampling at one point in time, further tests are required for the future.     

Long-term monitoring of post-fire aboveground biomass recovery in a lowland dipterocarp forest in East Kalimantan,Indonesia

Between 1988 and 2000, changes in the above-ground biomass (AGB) of trees in an East Kalimantan lowland forest, damaged by fires in 1982–83 and 1998, were estimated using allometric functions and an annual inventory of stem diameter. The original vegetation of the study site was lowland dipterocarp forest which has since been affected by selective logging and wild fires. The 1982–83 fire killed large trees of primary species and the opened sites became dominated by a few pioneer species. Between 1988 and 1997, a few pioneer tree species, namely Macaranga spp., dominated a heavily disturbed stand (HDS). Primary tree species that survived the 1982–83 fire dominated a lightly disturbed stand (LDS). A moderately disturbed stand (MDS) contained vegetation intermediate between the HDS and the LDS. In 1997, there were 553, 499 and 356 trees ha-1 in the HDS, MDS and LDS, respectively. Macaranga trees accounted for 70, 40 and 11 of the total number of trees in the HDS, MDS, and LDS, respectively. In 1997, the AGB of trees in the HDS, MDS, and LDS was 117, 280, and 315 Mg ha-1, respectively. The proportion of biomass accounted for by Macaranga trees for the HDS, MDS, and LDS was 34, 8 and 1, respectively. The pioneer trees did not compensate for the loss of aboveground biomass resulting from the death of large primary trees. The fire in 1998 again decreased AGB of the stands. In 2000, the AGB of trees in the HDS, MDS, and LDS was 27, 106, and 219 Mg ha-1, respectively. The sites opened up by the 1998 fire were covered with the pioneer seedlings and seemingly dominated by the pioneer trees with a larger number of stems per ha, but lower biomass as compared to the original forest (> 400 Mg ha-1).     

Greenhouse gas emissions during co-composting of cattle mortalities with manure

Following outbreaks of bovine spongiform encephalopathy (BSE), fewer cattle mortalities are being rendered. Composting may be a viable on-farm alternative for disposal of cattle carcasses. A study was conducted to assess feasibility and greenhouse gas (GHG) emissions during co-composting of cattle mortalities and manure. Using a tractor-mounted front-end loader, windrows were constructed containing manure + straw (control; CK) or manure + straw + cattle mortalities (cattle mortality; CM). The composting process lasted 310 d. The windrows were turned twice, at days 93 and 211, using either a tractor-mounted front-end loader or a specialized shredder bucket. Maximum windrow temperatures were >50 °C for 36 out of 92 d (before first turning) and 142 out of 208 d (after first turning) for the CM treatment and cattle mortalities were completely decomposed except for a few large bones. The cumulative CO₂ and CH₄ emissions were significantly affected by the mortality treatment, but not by the turning technology or their interactions. Significantly higher CO₂ (53.6 g d⁻¹ m⁻²) and CH₄ (2.204 g d⁻¹m⁻²) emissions were observed during the co-composting of cattle mortalities than manure composted with straw (23.0 and 0.742 g d⁻¹m⁻² for CO₂ and CH₄, respectively). Similarly, N₂O emissions were higher with mortalities than without and, for the CM treatment only, higher with shredder bucket than front-end loader turning. In the final compost, CM had higher TN and NH₄⁺-N contents than CK while TC and the C/N ratio were higher with compost turned with the front-end loader than with the shredder bucket. In conclusion, composting was an effective means of disposing of cattle mortalities, but did increase GHG emissions and the N content in the final compost. It is not known if GHG emissions are different than those that would be released from natural decomposition of carcasses. The higher N content in compost containing mortalities would increase its agronomic value.     

Spatial patterns of greenhouse gas emission in a tropical rainforest in Indonesia

Spatial patterns of CO₂, CH₄, and N₂O flux were analyzed in the soil of a primary forest in Sumatra, Indonesia. The fluxes were measured at 3-m intervals on a sampling grid of 8 rows by 10 columns, with fluxes found to be below the minimum detection level at 12 points for CH₄ and 29 points for N₂O. All three gas fluxes distributed log-normally. The means and standard deviations of CO₂ and CH₄ fluxes calculated by the maximum likelihood method were 3.68 ± 1.32 g C m^–2 d^–1 and 0.79 ± 0.60 mg C m^–2 d^–1, respectively. The mean and standard deviation of N₂O fluxes using a maximum likelihood estimator for the censored data set was 2.99 ± 3.26 g N m^–2 h^–1. The spatial dependency of CH₄ fluxes was not detected in 3-m intervals, while weak spatial dependency was observed in CO₂ and N₂O fluxes. The coefficients of variation of CH₄ and N₂O were higher than that of CO₂. Some hot spots where high levels of CH₄ and N₂O were generated in the studied field may increase the variability of these gases. The resulting patterns of variability suggest that sampling distances of >10 m and > 20 m are required to obtain statistically independent samples for CO₂ and N₂O flux in the studied field, respectively. But because of weak or no spatial dependency of each flux, a sampling distance of more than 10 m intervals is enough to prevent a significant problem of autocorrelation for each flux measurement.     

Reduction of Greenhouse Gas Emissions from Gas,Oil, and Coal Power Plants in Pakistan by Carbon Capture and Storage (CCS): A Review

The production of energy in Pakistan as a developing country mainly depends on consumption of fossil fuels, which are the main sources of greenhouse gas (GHG) emissions. These emissions can be mitigated by implementing carbon capture and storage (CCS) in running plants. An overview of the current and future potentials of Pakistan for CCS is provided, indicating a great potential for this technology to capture CO₂ emissions. The amine CO₂ capture process as the most mature procedure is currently applied in many oil and gas companies in Pakistan, which can be employed to capture CO₂ from other industries as well. Pakistan has a great CO₂ storage potential in oil, gas, and coal fields and in saline aquifer as well as significant resources of Mg and Ca silicates suitable as feedstock in the carbon mineralization process. For further development and implementation of CCS technologies in Pakistan, economic and policy barriers as the main obstacles should be alleviated.     

Potential of agroforestry for carbon sequestration and mitigation of greenhouse gas emissions from soils in the tropics

Losses of carbon (C) stocks in terrestrial ecosystems and increasing concentrations of greenhouse gases in the atmosphere are challenges that scientists and policy makers have been facing in the recent past. Intensified agricultural practices lead to a reduction in ecosystem carbon stocks, mainly due to removal of aboveground biomass as harvest and loss of carbon as CO₂ through burning and/or decomposition. Evidence is emerging that agroforestry systems are promising management practices to increase aboveground and soil C stocks and reduce soil degradation, as well as to mitigate greenhouse gas emissions. In the humid tropics, the potential of agroforestry (tree-based) systems to sequester C in vegetation can be over 70 Mg C ha^–1, and up to 25 Mg ha^–1 in the top 20 cm of soil. In degraded soils of the sub-humid tropics, improved fallow agroforestry practices have been found to increase top soil C stocks up to 1.6 Mg C ha^–1 y^–1 above continuous maize cropping. Soil C accretion is linked to the structural development of the soil, in particular to increasing C in water stable aggregates (WSA). A review of agroforestry practices in the humid tropics showed that these systems were able to mitigate N₂O and CO₂ emissions from soils and increase the CH₄ sink strength compared to cropping systems. The increase in N₂O and CO₂ emissions after addition of legume residues in improved fallow systems in the sub-humid tropics indicates the importance of using lower quality organic inputs and increasing nutrient use efficiency to derive more direct and indirect benefits from the system. In summary, these examples provide evidence of several pathways by which agroforestry systems can increase C sequestration and reduce greenhouse gas emissions.     

Effect of changing groundwater levels caused by land-use changes on greenhouse gas fluxes from tropical peat lands

Monthly measurements of carbon dioxide (CO₂), methane (CH₄) and nitrous oxide (N₂O) fluxes in peat soils were carried out and compared with groundwater level over a year at four sites (drained forest, upland cassava,upland and lowland paddy fields) located in Jambi province, Indonesia. Fluxes from swamp forest soils were also measured once per year as the native state of this investigated area. Land-use change from drained forest to lowland paddy field significantly decreased the CO₂ (from 266 to 30 mg C m^–2 h^–1) and N₂O fluxes (from 25.4 to 3.8 g N m^–2 h^–1), but increased the CH₄ flux (from 0.1 to 4.2 mg C m^–2 h^–1) in the soils. Change from drained forest to cassava field significantly increased N₂O flux (from 25.4 to 62.2 g N m^–2 h^–1), but had no significant influence on CO₂ (from 266 to 200 mg C m^–2 h^–1) and CH₄ fluxes (from 0.1 to 0.3 mg C m^–2 h^–1) in the soils. Averaged CO₂ fluxes in the swamp forests (94 mg C m^–2 h^–1) were estimated to be one-third of that in the drained forest. Groundwater levels of drained forest and upland crop fields had been lowered by drainage ditches while swamp forest and lowland paddy field were flooded, although groundwater levels were also affected by precipitation. Groundwater levels were negatively related to CO₂ flux but positively related to CH₄ flux at all investigation sites. The peak of the N₂O flux was observed at –20 cm of groundwater level. Lowering the groundwater level by 10 cm from the soil surface resulted in a 50 increase in CO₂ emission (from 109.1 to 162.4 mg C m^–2 h^–1) and a 25% decrease in CH₄ emission (from 0.440 to 0.325 mg C m^–2 h^–1) in this study. These results suggest that lowering of groundwater level by the drainage ditches in the peat lands contributes to global warming and devastation of fields. Swamp forest was probably the best land-use management in peat lands to suppress the carbon loss and greenhouse gas emission. Lowland paddy field was a better agricultural system in the peat lands in terms of C sequestration and greenhouse gas emission. Carbon loss from lowland paddy field was one-eighth of that of the other upland crop systems, although the Global Warming Potential was almost the same level as that of the other upland crop systems because of CH₄ emission through rice plants.     

Greenhouse gas emissions and final compost properties from co-composting bovine specified risk material and mortalities with manure

The increased disposal costs of cattle specified risk materials (SRM) have reduced the competitiveness of the Canadian beef industry. The SRM materials include the skull, brain, trigeminal ganglia, eyes, palatine tonsils, spinal cord and dorsal root ganglia. This study investigates greenhouse gas (GHG) emissions and final compost properties from open windrow co-composting of manure with bovine SRM and mortalities. There were two compost treatments with four replications: SRMC consisting of SRM, cattle manure and barley straw and COWC consisting of cattle mortalities, cattle manure and barley straw. Average windrow temperature was higher (P < 0.05) for SRMC (47.1°C) than for COWC (44.1°C) over the first 139 days. The final compost coliform count, moisture, pH and TC contents were not significantly different between treatments while TN and available N (NH₄ ⁺ + NO₃ ⁻ + NO₂ ⁻) were lower for SRMC than for COWC. The average surface GHG flux from SRMC were 24.3 g C day⁻¹ m⁻² and 0.17 g N day⁻¹ m⁻² for CO₂ and N₂O, respectively, and were not significantly different from those from COWC (31.6 g C day⁻¹ m⁻² and 0.17 g N day⁻¹ m⁻² for CO₂ and N₂O, respectively), but CH₄ emissions from SRMC (0.47 g C day⁻¹ m⁻²) were lower than from COWC (1.57 g C day⁻¹ m⁻²). While a few large bones were left in the cattle mortality treatment, composting decomposed all SRM suggesting that it may be a viable alternative to rendering for SRM disposal.     

An evaluation of autotrophic microbes for the removal of carbon dioxide from combustion gas streams

Carbon dioxide is a greenhouse gas that is believed to be a major contributor to global warming. Studies have shown that significant amounts of CO₂ are released into the atmosphere as a result of fossil fuels combustion. Therefore, considerable interest exists in effective and economical technologies for the removal of CO₂ from fossil fuel combustion gas streams. This work evaluated the use of autotrophic microbes for the removal of CO₂ from coal fired power plant combustion gas streams. The CO₂ removal rates of the following autotrophic microbes were determined: Chlorella pyrenoidosa, Euglena gracilis, Thiobacillus ferrooxidans, Aphanocapsa delicatissima, Isochrysis galbana, Phaodactylum tricornutum, Navicula tripunctata schizonemoids, Gomphonema parvulum, Surirella ovata ovata, and four algal consortia. Of those tested, Chlorella pyrenoidosa exhibited the highest removal rate with 2.6 g CO₂ per day per g dry weight of biomass being removed under optimized conditions. Extrapolation of these data indicated that to remove CO₂ from the combustion gases of a coal fired power plant burning 2.4 × 10⁴ metric tons of coal per day would require a bioreactor 386 km² × 1 m deep and would result in the production of 2.13 × 10⁵ metric tons (wet weight) of biomass per day. Based on these calculations, it was concluded that autotrophic CO₂ removal would not be feasible at most locations, and as a result, alternate technologies for CO₂ removal should be explored.     

Greenhouse gas emissions from simulated beef and dairy livestock systems in the United States

Computer spreadsheets were developed to evaluate greenhouse gas (GHG) emissions from U.S. beef and dairy livestock systems from nine locations. Of the beef systems the cow-calf herd emitted the most and feedlot cattle the least methane (CH₄) and nitrous oxide (N₂O) per unit product. Carbon dioxide (CO₂) emissions per unit product were the least for the cow-calf and greatest for the feedlot scenarios. In the dairy systems approximately one-half of the total GHG CO₂ equivalents were from CH₄ and one-third from N₂O. Mitigation strategies, such as intensive grazing, reduced GHG emissions by approximately 10%. This revised version was published online in August 2006 with corrections to the Cover Date.     

Effect of climate change on greenhouse gas emissions from arable crop rotations

The DAISY soil–plant–atmosphere model was used to simulate crop production and soil carbon (C) and nitrogen (N) turnover for three arable crop rotations on a loamy sand in Denmark under varying temperature, rainfall, atmospheric CO₂ concentration and N fertilization. The crop rotations varied in proportion of spring sown crops and use of N catch crops (ryegrass). The effects on CO₂ emissions were estimated from simulated changes in soil C. The effects on N₂O emissions were estimated using the IPCC methodology from simulated amounts of N in crop residues and N leaching. Simulations were carried out using the original and a revised parameterization of the soil C turnover. The use of the revised model parameterization increased the soil C and N turnover in the topsoil under baseline conditions, resulting in an increase in crop N uptake of 11 kg N ha^–1 y^–1 in a crop rotation with winter cereals and a reduction of 16 kg N ha^–1 y^–1 in a crop rotation with spring cereals and catch crops. The effect of increased temperature, rainfall and CO₂ concentration on N flows was of the same magnitude for both model parameterizations. Higher temperature and rainfall increased N leaching in all crop rotations, whereas effects on N in crop residues depended on use of catch crops. The total greenhouse gas (GHG) emission increased with increasing temperature. The increase in total GHG emission was 66–234 kg CO₂-eq ha^–1 y^–1 for a temperature increase of 4°C. Higher rainfall increased total GHG emissions most in the winter cereal dominated rotation. An increase in rainfall of 20% increased total GHG emissions by 11–53 kg CO₂-eq ha^–1 y^–1, and a 50% increase in atmospheric CO₂ concentration decreased emissions by 180–269 kg CO₂-eq ha^–1 y^–1. The total GHG emissions increased considerably with increasing N fertilizer rate for a crop rotation with winter cereals, but remained unchanged for a crop rotation with spring cereals and catch crops. The simulated increase in GHG emissions with global warming can be effectively mitigated by including more spring cereals and catch crops in the rotation.     

Greenhouse gas emissions of bioenergy from agriculture compared to fossil energy for heat and electricity supply

Increasing the use of bioenergy is one promising option to reduce greenhouse gas emissions. Hence it is important to know the greenhouse gas emissions of bioenergy systems in comparison to fossil fuel systems. A life cycle analyses of biomass and fossil fuel energy systems is made to compare the overall greenhouse gas emission of both systems for heat and electricity supply. Different bioenergy systems to supply electricity and heat from agriculture are analysed for the Austrian situation in 2000. Total emissions of greenhouse gases (CO₂, N₂O, CH₄) along the fuel chain, including land use change and by-products, are calculated. The systems taken into consideration are different conversion technologies and different fuels from agriculture. The methodology was developed within the International Energy Agency (IEA) Bioenergy Task 25 on `Greenhouse Gas Balances of Bioenergy Systems'. In this paper the results of selected bioenergy systems for heat supply and combined supply of electricity and heat shown as emission of CO₂-equivalents per kWh for bioenergy systems in comparison to fossil fuel systems, and as a percentage of CO₂-equivalent reduction. The results demonstrate that some of the bioenergy systems reduce greenhouse gas emission already because of avoided emissions of the reference biomass use and/or because of certain substitution effects of by-products. In general the greenhouse gas emissions of bioenergy systems are lower compared to the fossil systems. Therefore a significant reduction of greenhouse gases is possible by replacing fossil energy systems with bioenergy systems. This comparison should help policy makers, utilities and industry to identify effective agricultural biomass options in order to reach emission reduction targets. This revised version was published online in August 2006 with corrections to the Cover Date.     

Burning and cultivation effects on greenhouse gas emissions and nutrients in wetland soils from Saskatchewan,Canada

Wetland fringe areas in prairie agricultural landscapes may be subjected to burning of vegetation in autumn followed by cultivation in spring. The objective of this study was to examine the greenhouse gas (CO₂, N₂O and CH₄) emissions and plant nutrient (NO₃, PO₄ and SO₄) supplies in wetland fringe soils as affected by simulated burning + cultivation, at field capacity and saturation moisture content. Using undisturbed soil cores collected from grassed wetland fringes at four sites in southern Saskatchewan, the impacts were examined over a 20-day period. The burning + cultivation treatment generally reduced CO₂ emissions, tended to increase NO₃–N availability, and had no consistent effect on N₂O emissions, or PO₄–P and SO₄–S supply. Production of CH₄ occurred only at one site, and only under saturated conditions. Compared to field capacity, saturation reduced CO₂ emissions and NO₃–N supply, tended to increase PO₄–P availability, and had no consistent effect on N₂O emissions and SO₄–S. The CO₂ emissions and SO₄–S were greater for soil cores with higher organic matter and salinity, respectively. The N₂O emissions were only occasionally related to soil NO₃–N supply rate.     

Treatments of low rank coals for improved power generation and reduction in Greenhouse gas emissions

Reduction in ash constituents by water washing, and also at specific pH values, was systematically studied for three low-rank coals. Acid treatment removed inorganic constituents if accompanied by efficient water washing; at elevated temperatures this can also reduce moisture. The ash components are present in the coal matrix and also as numerous aluminosilicates particles containing K, Na, Mg, Fe and Ca; acid treatment reduced the ash constituents to mainly quartz and clay particles. The ash chemistry of treated and untreated coals was studied over the temperature range 800 °C to 1400 °C. The ash from treated coals consisted mostly of α-quartz, and when heated at 800 °C to 1500 °C, was transformed into mainly amorphous silica and cristobalite, and melted at 1300–1500 °C. Ash from untreated coals melted at or below 1100 °C. The impact of low rank coals with lower moisture, and also coals with lower ash and moisture, was assessed for power generation using the GateCycle™ package. The results show: (i) moisture reduction lowers CO₂/MWh by a small amount but often increases fouling, and (ii) reduction in ash and moisture would eliminate ash fouling and significantly reduce the CO₂/MWh compared with current power plant.     

Interaction of Regulatory Aspects for Carbon Capture and Utilization Applications

Carbon capture and utilization (CCU) technologies can lead to a net reduction of CO₂ emissions but also to a transfer from emissions between different regulatory areas. This paper presents a tool to evaluate the impact of CCU technology within the European regulatory framework with respect to the accounting of carbon transferred between the CO₂ source and its subsequent application. Additional emissions caused by energy requirements of the capture or any conversion steps are not considered. The tool is applied to a variety of possible combinations and their respective impact evaluated.     

Estimates of the interannual variations of N2O emissions from agricultural soils in Canada

The DNDC model was used to estimate direct N₂O emissions from agricultural soils in Canada from 1970 to 1999. Simulations were carried out for three soil textures in seven soil groups, with two to four crop rotations within each soil group. Over the 30-year period, the average annual N₂O emission from agricultural soils in Canada was found to be 39.9 Gg N₂O–N, with a range from 20.0 to 77.0 Gg N₂O–N, and a general trend towards increasing N₂O emissions over time. The larger emissions are attributed to an increase in N-fertilizer application and perhaps to a trend in higher daily minimum temperatures. Annual estimates of N₂O emissions were variable, depending on timing of rainfall events and timing and duration of spring thaw events. We estimate, using DNDC, that emissions of N₂O in eastern Canada (Atlantic Provinces, Quebec, Ontario) were approximately 36% of the total emissions in Canada, though the area cropped represents 19% of the total. Over the 30-year period, the eastern Gleysolic soils had the largest average annual emissions of 2.47 kg N₂O–N ha^–1 y^–1 and soils of the dryer western Brown Chernozem had the smallest average emission of 0.54 kg N₂O–N ha^–1 y^–1. On average, for the seven soil groups, N₂O emissions during spring thaw were approximately 30% of total annual emissions. The average N₂O emissions estimates from 1990 to 1999 compared well with estimates for 1996 using the IPCC methodology, but unlike the IPCC methodology our modeling approach provides annual variations in N₂O emissions based on climatic differences.     

Technical and policy aspects of strategies to decrease greenhouse gas emissions from agriculture

Agricultural activities greatly contribute to the global net flux of CH₄, N₂O and CO₂ from the terrestrial biosphere into the atmosphere. For CH₄ and N₂O, the net contribution is in the order of 40%. Because of this relatively large contribution, there is an urgent need for the implementation of effective strategies to decrease the net flux of CH₄, N₂O and CO₂ from agriculture. The objectives of this paper are to review the various measures that have been proposed so far and to discuss the constraints and challenges. A large number of suggestions for decreasing emissions of CH₄, N₂O and CO₂ from agriculture can be found in literature. Common to most of these abatement measures is that the suggested potentials to decrease the emissions of CO₂, CH₄ and N₂O from agriculture are large. Common to most of the measures is also the `single gas' and `source-oriented' approach. In most papers it has been implicitly assumed that farmers are able and willing to implement the proposed measures. So far, none of the measures has been consciously implemented and tested at farm scale. The major challenge of policy makers is to formulate effective and efficient policies and measures, using the potentials of the abatement measures proposed so far, and in an international setting with still highly uncertain cause–effect relationships. Major constraints for policy makers follow from the complexities and possible feed back and side effects of abatement measures, from the many stakeholders involved, often with contrasting views, and from the unfamiliarity of farmers with the problem of climate change. Because of the many complexities and interactions involved, policy makers should follow two tracks. Priority should be given to chain-oriented measures, i.e. measures that aim at an increased carbon, nitrogen and water use efficiencies in the whole food chain, above source-oriented measures, i.e. measures that aim at decreased emission from specific sources. Chain-oriented measures should fit in with other environmental policies that aim at increasing resource use efficiency, to be effective and efficient. This revised version was published online in August 2006 with corrections to the Cover Date.     

燃气-蒸汽联合循环机组烟气氮氧化物的排放规律

针对燃气-蒸汽联合循环机组运行过程中排放黄烟的现象,开展了烟气污染物（NO和NO₂）浓度的现场测试,研究了联合机组运行工况和生产负荷对其排放特性及变化规律的影响。结果表明：烟气中NO浓度和氮氧化物（NO _x ）浓度随机组生产负荷的增大而增大,NO₂浓度以及NO₂与NO _x 的浓度比值（NO _x 构成）则随生产负荷增加而逐渐降低。联合机组在单循环和低负荷工况运行时,黄色烟羽成因是烟气中NO₂含量高造成的,与烟气中NO _x 浓度和NO浓度没有明确的对应关系;提高联合机组生产负荷,会减少NO₂在氮氧化物中所占的比例,有助于缓解烟气黄色烟羽的生成。此外,初步分析了燃气轮机燃烧器的运行模式,认为值班燃烧区形成的高温富氧条件是造成排放高浓度NO₂烟气的重要原因。     

光催化氧化NO研究进展

烟气光催化脱硝技术是面向烟气净化过程的一种环境友好型处理工艺。开发高效稳定的光催化材料是光催化技术大规模应用的关键和基础。本文综述了光催化脱硝技术反应影响因素以及提高光催化脱硝效率的方法,并基于光催化脱硝技术研究的现状,对其研究方向提出建议。