pH对土壤生物炭固碳效果的影响及机制

发布时间：2018-03-15 19:54

本文选题：生物炭　切入点：CO_2释放　出处：《浙江大学》2017年博士论文　论文类型：学位论文

【摘要】：土壤生物炭固碳是当前最具潜力的温室气体减排技术之一。研究发现生物炭不仅能固定生物质中的有机碳,减少温室气体排放,还能增加土壤肥力,缓解土壤酸化,吸附重金属及有机污染物。迄今对土壤中加入生物炭后CO_2释放变化尚存在争议,pH作为土壤重要的参数,能够对生物炭投加后土壤的物理化学及生物过程产生作用,从而影响生物炭固碳减排效应。目前有关pH对土壤生物炭固碳减排效应影响及微观机制的研究较少。为此本文模拟旱地条件,在测定不同pH的六种土壤加入生物炭后的CO_2排放的基础上,通过同位素分析及高通量测序的方法,研究了 pH对无机碳释放、生物炭降解、有机质稳定性及微生物群落的影响,试图探明pH影响生物炭固碳减排的微观机制,为提高土壤生物炭固碳减排效率及潜力估算提供科学依据。论文取得了一些有价值的结果:(1) 土壤pH可以通过改变生物炭中碳酸盐溶解、表面官能团构成及有机质溶出影响生物炭的降解。在4.34-7.91范围内,土壤pH越低,生物炭中碳酸盐更易溶解形成CO_2,且表面基团中的C-O及OH结构增多,更易被老化。酸性土壤(pH7)中加入生物炭后CO_2释放量明显增加,而碱性土壤(pH7)加入生物炭后CO_2释放量减少,且增加和减小的幅度随生物炭的投加量增加而增长。(2) 土壤pH是影响土壤微生物结构及CO_2排放最重要的因素,且与其他因素有很强的相关性。生物炭能通过增加酸性土壤pH及其有机质的微生物可利用性,降低细菌生长底物限制,促进富营养菌的增长,从而促进其CO_2排放,生物炭热解温度降低,促进作用越强。而在碱性土壤中由于生物炭对易降解有机质的吸附作用,贫营养菌微弱增加,微生物量减小,抑制土壤CO_2排放。长期固碳过程中,有机-矿物结合重要性逐渐突出,且随pH减小有机质稳定性更强。(3)生物炭降解率、生物炭对土壤有机质降解的激发效应与土壤的C-/G+呈负相关。土壤G-/G+越小,微生物偏向于利用芳环类有机质,生物炭降解增加。我国酸性土壤占总耕作土壤的27%左右,这类土壤在实际的农业过程中的生物炭固碳潜力被高估,可以通过配合添加秸秆或添加生石灰等方式,加强生物炭的固碳减排效果。
[Abstract]:Soil biochar sequestration is one of the most promising greenhouse gas emission reduction technologies. The study found that biochar can not only immobilize organic carbon from biomass, reduce greenhouse gas emissions, but also increase soil fertility and mitigate soil acidification. Adsorption of heavy metals and organic pollutants. Up to now, the pH value of CO_2 release after adding biochar into soil has been disputed as an important parameter of soil, which can play an important role in the physical, chemical and biological processes of soil after adding biochar. Therefore, there are few studies on the effects of pH on soil carbon sequestration and its microscopic mechanism. Therefore, the dry land conditions are simulated in this paper. The effects of pH on the release of inorganic carbon, degradation of biochar, stability of organic matter and microbial community were studied by means of isotope analysis and high-throughput sequencing on the basis of CO_2 emission from six soils with different pH values. Trying to find out the micromechanism of pH effect on carbon reduction of biochar, In order to improve the efficiency and potential estimation of carbon abatement in soil biochar, some valuable results have been obtained in this paper: (1) soil pH can be dissolved by changing carbonate in biochar. The composition of surface functional groups and the dissolution of organic matter affected the degradation of biochar. In the range of 4.34-7.91, the lower soil pH, the easier dissolution of carbonate in biochar to form CO _ 2, and the increase of C-O and OH structures in surface groups. The amount of CO_2 released in acidic soil increased significantly after adding biochar, but in alkaline soil, CO_2 release decreased after adding biochar. Soil pH was the most important factor affecting soil microbial structure and CO_2 emission. Biochar can reduce the bacterial growth substrate limit and promote the growth of eutrophic bacteria by increasing the microbial availability of pH and organic matter in acidic soil, thus promoting its CO_2 emission. The biochar pyrolysis temperature is lower and the promoting effect is stronger. However, because of the adsorption of biochar to easily degradable organic matter in alkaline soil, the poor nutrition bacteria increase slightly, the microbial biomass decreases, and the CO_2 emission from soil is inhibited, and during the long-term carbon sequestration process, The importance of organic-mineral combination became more and more prominent, and the degradation rate of organic matter was stronger with the decrease of pH value. The activation effect of biochar on soil organic matter degradation was negatively correlated with the C / R G of soil. The smaller the soil G / / G was, the smaller the degradation rate of biochar was. Microorganisms tend to make use of aromatic organic matter and increase the degradation of biochar. Acid soils in China account for about 27% of the total cultivated soils. The potential of biochar sequestration in this kind of soil is overestimated in the actual agricultural process. The carbon reduction effect of biochar can be enhanced by adding straw or lime.
【学位授予单位】：浙江大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：S153;S154

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