Gaseous and particulate emission profiles during controlled rice straw burningSanchis, E 1 ., Ferrer, M 1 ., Calvet, S 1 ., Coscollà, C 2 ., Yusà, V 2 ., Cambra-López, M 1 . AbstractBurning of rice straw can emit considerable amounts of atmospheric pollutants. We evaluated the effect of rice straw moisture content (5%, 10% and 20%) on the emission of carbon dioxide (CO 2 ) and on the organic and inorganic constituents of released particulate matter (PM): dioxins, heavy metals, and polycyclic aromatic hydrocarbons (PAHs). Four burning tests were conducted per moisture treatment using the open chamber method. Gaseous emission profiles of carbon monoxide (CO), sulfur dioxide (SO 2 ), nitrogen monoxide (NO), and nitrogen dioxide (NO 2 ) were also measured. Additionally, combustion characteristics, including burning stages, durations, combustion efficiency, temperature, and relative humidity, were recorded. Burning tests showed flaming and smoldering stages were significantly longer in 20% moisture treatment (P<0.05) compared with the rest. The amount of burned straw and ashes decreased with increasing straw moisture content (P<0.001). Carbon dioxide was the main product obtained during combustion with emission values ranging from 692 g CO 2 kg dry straw -1 (10% moisture content) to 835 g CO 2 kg dry straw -1 (20% moisture content). Emission factors for PM were the highest in 20% moisture treatment (P<0.005). Fine PM (PM2.5) accounted to more than 60% of total PM mass. Emission factors for dioxins increased with straw moisture content, being the highest in 20% moisture treatment, although showing a wide variability among burning tests (P>0.05). Emissions factors for heavy metals were low and similar among moisture treatments (P>0.05). Emission factors for individual PAHs were generally higher in 20% moisture treatment. Average SO 2 and NO emissions decreased with moisture content. In contrast, CO emissions increased with moisture content.Overall, emission factors of atmospheric pollutants measured in our study were higher in the 20% moisture content. This difference could be attributed to the incomplete combustion at higher levels *Manuscript Click here to download Manuscript: Quema_sin tablas ni figuras_cor.docx Click here to view linked References 2 of rice straw moisture content. According to our results, rice straw burning should be done after straw drying and under minimal moisture conditions to lower pollutant emission levels.
Running titleRice management practices and methane emissions 2 AbstractRice fields contribute substantially to global warming of the atmosphere through the emission of methane (CH4). This paper reviews the state-of-the-art of factors affecting CH4 emissions in rice fields, focusing on soil organic matter content and water management practices. It establishes a quantitative relationship between these factors based on a literature survey through a meta-analysis, useful to update the emission factors used to estimate CH4 in National Emission Inventories. Methane emissions in rice fields can be as much as 90% higher in continuously flooded rice fields compared with other water management systems, independent from straw addition. Water management systems which involve absence of flooding in total or part of the growing period such as midseason drainages, intermittent flooding and percolation control can reduce CH4 emissions substantially. Moreover, CH4 emissions increase with the amount of straw added until 7.7 t/ha for continuously flooded soils and until 5.1 t/ha for other water regimes. Above these levels, no further increase is produced with further addition of straw. As regards to rice straw management mitigation strategies, recommended practices are: composting rice straw, straw burning under controlled conditions, recollecting rice straw for biochar production, generation of energy, to be used as a substrate, or to obtain other by-products with added value. This review improves the understanding of the relationship between straw application rate, water regimes and CH4 emissions from rice fields to date. This relationship can help to select the most appropriate management practices to improve current mitigation strategies to reduce atmospheric CH4.
Background Evidence from the scientific literature shows a significant variation in greenhouse gas (GHG) emissions from the diet, according to the type of food consumed. We aim to analyze the relationship between the daily dietary GHG emissions according to red meat, fruit and vegetables consumption and their relationship with risk of total mortality, and incident risk of chronic diseases. Methods We examined data on the EPIC-Spain prospective study, with a sample of 40 621 participants. Dietary GHG emission values were calculated for 57 food items of the EPIC study using mean emission data from a systematic review of 369 published studies. Results Dietary GHG emissions (kgCO2eq/day), per 2000 kcal, were 4.7 times higher in those with high red-meat consumption (>140 g/day) than those with low consumption (<70 g/day). The average dietary GHG emissions were similar in males and females, but it was significantly higher in youngest people and in those individuals with lower educational level, as well as for northern EPIC centers of Spain. We found a significant association with the risk of mortality comparing the third vs. the first tertile of dietary GHG emissions [hazard ratio (HR) 1.095; 95% confidence interval (CI) 1.007–1.19; trend test 0.037]. Risk of coronary heart disease (HR 1.26; 95% CI 1.08–1.48; trend test 0.003) and risk of type 2 diabetes (HR 1.24; 95% CI 1.11–1.38; trend test 0.002) showed significant association as well. Conclusions Decreasing red-meat consumption would lead to reduce GHG emissions from diet and would reduce risk of mortality, coronary heart disease and type 2 diabetes.
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