秸秆生物质炭在淹水稻田土壤中的矿化特性及其潜在的固碳效应研究

发布时间：2018-03-23 06:12

  本文选题：水稻秸秆生物质炭　切入点：稻田土壤　出处：《浙江大学》2015年硕士论文　论文类型：学位论文

【摘要】：为应对逐渐加剧的全球气候变暖,碳捕捉与储存技术的研发迫在眉睫。生物质炭由于具有高度的化学及生物稳定性,可以在环境中存在几百年至上千年。因此,生物质炭化还田技术有望成为土壤生态系统碳捕捉与储存的有效途径。而这项技术的核心是生物质炭在土壤生态系统中的稳定性。生物质炭稳定性是其在土壤生态系统中固碳效应的重要预测与评估指标。它不仅受生物质炭理化特性影响,土壤理化性质及其环境条件也发挥着重要的作用。本论文以水稻秸秆制备的生物质炭为试材,通过应用稳定态碳同位素标记与分析技术,对实验室模拟条件下秸秆生物质炭在不同类型淹水稻田土壤中的矿化特性进行了研究,并通过双指数模型对矿化过程进行拟合,分析预测了秸秆生物质炭在不同类型淹水稻田土壤中的稳定性。研究结果为科学评估秸秆生物质炭化还田技术在稻田生态系统中的固碳效应提供了理论依据。主要研究结果如下：(1)以水稻秸秆制备的生物质炭为实验材料,选取不同纬度上的五种不同类型稻田土壤,在实验室培养条件下对秸秆生物质炭在淹水稻田土壤中的矿化特性进行了探究。结果表明,在390天的培养时间内,不同类型稻田土壤中秸秆生物质炭的累积矿化率处于0.17%-0.28%之间(相对较低),证明500℃条件下草本植物秸秆制备的生物质炭与木本植物一样,具有高度的稳定性。秸秆生物质炭在不同类型稻田土壤中的累积矿化率不同,造成这种差异的主要原因可能是生物质炭稳定组分在本底有机碳含量不同的土壤中降解速率不同。通过相关性分析可以发现,培养150天后生物质炭累积矿化率与不同土壤的本底有机碳含量成显著正相关关系。随着土壤内源有机碳含量的增加,微生物共代谢作用增强从而导致了培养后期生物质炭累积矿化率的增加。(2)利用双指数模型对秸秆生物质炭在390天培养过程中的矿化作用进行拟合,分析预测和评估了秸秆生物质炭在不同类型稻田土壤中的平均停留时间(MRT)及其固碳效应。研究发现,秸秆生物质炭不稳定碳组分在不同类型土壤中的MRT为18-37天,而稳定碳组分的MRT为617-2829年,且稳定碳组分的MRT与土壤本底有机碳含量成显著负相关关系。从长期的固碳效应考虑,秸秆生物质炭可能更适用于有机质含量较低的浅潮粘田土壤。(3)FTIR和XPS分析表明秸秆生物质炭在五种不同类型的稻田土壤中均发生了一定程度的氧化,这种氧化主要是由于含碳官能团(脂肪族C-H、芳香化C=C和烯烃类C-H)转化成了含氧官能团(C-O、C=O和COO)。此外,秸秆炭的C-C、C-H和C=C官能团在黄砖土(GD)降低得最为明显(降低了39.3%),表明秸秆炭在有机质含量最高的黄砖土(GD)中的氧化最剧烈,而这种氧化可能是由于秸秆炭对于土壤有机质的C-O-C官能团吸附作用较强导致的。
[Abstract]:In order to cope with the increasing global warming, the development of carbon capture and storage technology is urgent. Because of its high chemical and biological stability, biomass carbon can exist in the environment for hundreds to thousands of years. Biomass carbonization is expected to be an effective way to capture and store carbon in soil ecosystem. The core of this technology is the stability of biomass carbon in soil ecosystem. The important prediction and evaluation index of carbon sequestration effect in the state system is not only affected by the physicochemical properties of biomass carbon, but also by the physical and chemical properties of biomass carbon. The physical and chemical properties of soil and its environmental conditions also play an important role. In this paper, biomass carbon prepared from rice straw was used as test material, and stable carbon isotope labeling and analysis techniques were used. The mineralization characteristics of straw biomass carbon in different types of flooded paddy soil were studied under simulated conditions in laboratory, and the mineralization process was fitted by double exponential model. The stability of straw biomass carbon in different types of flooded paddy soil was analyzed and predicted. The results provided a theoretical basis for the scientific evaluation of carbon sequestration effect of straw biomass carbonization in paddy ecosystem. The results of the study are as follows: (1) using biomass carbon prepared from rice straw as the experimental material, Five different types of paddy soils at different latitudes were selected to study the mineralization characteristics of straw biomass carbon in flooded paddy soil under laboratory culture conditions. The results showed that the mineralization time was 390 days. The cumulative mineralization rate of straw biomass carbon in different types of paddy soil was between 0.17% and 0.28% (relatively low), which proved that the biomass carbon produced by straw of herbaceous plants was the same as that of woody plants at 500 鈩，

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