摘要
生物炭是生物质在无氧或限氧条件下经高温热解后产生的多孔富碳物质,其被广泛施加到土壤中改良土壤性质,调节温室气体排放。生物炭施入土壤后,长期受外界物理、化学和生物等环境作用导致生物炭性质发生缓慢改变,这个过程称为生物炭的老化。文章综述了原位生物炭自然老化和实验室模拟老化的方法以及老化后生物炭理化性质的变化,从理化性质变化的角度论述了生物炭老化过程对二氧化碳(CO2)、甲烷(CH4)和氧化亚氮(N2O)这3种温室气体排放的影响,并初步解释生物炭老化过程对增加或减少温室气体排放的可能机制。主要内容如下:生物炭老化方法可以分为自然老化和人工模拟老化,模拟老化方法包括生物、物理和化学老化。生物炭发生老化后,生物炭的比表面积(SSA)和孔容根据老化强度而有不同变化,自然或人工模拟的温和老化方法使生物炭表面上有新的纳米微孔生成,生物炭SSA增加,而使用强酸或强氧化剂的强烈老化方式可破坏生物炭孔隙结构,导致SSA和孔容下降。从化学性质方面来讲,生物炭C/N比随老化过程而降低,但是O/C比却随老化过程而升高;此外,当生物炭老化时,生物炭表面含氧官能团增加,例如羧基、羰基和酚基等,这些含氧基团可以和阳离子结合形成羧酸盐和酚盐,同时释放H^+,导致老化生物炭的pH值降低。基于有限的研究报道,老化生物炭仍然具有一定的CH4减排潜力,这得益于土壤通气状态的改善和甲烷氧化菌氧化CH4潜力提升。相反,由于生物炭极性增强和pH值降低,生物炭老化过程有促进土壤有机质矿化增加CO2和N2O排放的趋势。然而为了辅正这一论断,准确评估生物炭老化的环境效应,长期原位生物炭老化并同时设置新鲜生物炭对照的研究需要进一步开展,以探明生物炭老化过程对温室气体排放的影响机制,为生物炭生产和合理施用提供�
Biochar is a carbon-rich porous substance pyrolyzed from biomass at high temperature under anaerobic or oxygen-limited conditions. It is widely used as a soil amendment to ameliorate soil properties and mediate greenhouse gas emissions. When biochar is exposed to soil, its properties will slowly change due to physical weathering, chemical oxidizing or soil microbes metabolizing, which is described as biochar ageing. The paper reviews the methods of biochar ageing in the lab or in situ field and the changes of physicochemical properties after ageing. In addition, the paper also discusses the ageing effects of biochar on CH4, CO2 and N2O emissions, and tries to explain the possible mechanisms of increase or decrease emissions. The main contents are as follows. Besides the natural ageing, artificial aging methods, including physical, chemical and microbial ageing, are considered as proxies for natural ageing to accelerate biochar properties changes. Biochar physical properties, particularly specific surface area (SSA) and pore volume can change depending on the aging intensity. Natural or artificial mild aging methods can produce new nano-size pores on the surface and increase biochar SSA, while chemical aging using strong acids or oxidizing agents can reduce SSA and pore volume due to destruction of structures. In terms of the chemical properties, the biochar C/N ratio decreases with ageing. But the O/C ratio increases. Furthermore, when biochar is aged, some oxygen-containing functional groups, such as carboxylic, carbonyl and phenolic groups, are formed on the surface of biochar. These oxygen-containing groups can bind cations to form carboxylate and phenolate with H+ releasing, which leads to a lower pH in aged biochar. Based on the limited studies, the aged biochar still has a certain CH4 mitigation potential, supported by the enhanced aerobic conditions and elevated methanotrophs activity. On the contrary, the biochar aging process has a tendency to promote CO2 and N2O emissions due to increased biochar polari
作者
袁海静
邓桂森
周顺桂
秦树平
YUAN Haijing;DENG Guisen;ZHOU Shungui;QIN Shuping(Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation/College of Resources and Environment,Fujian Agriculture and Forestry University,Fuzhou 350002,China)
出处
《生态环境学报》
CSCD
北大核心
2019年第9期1907-1914,共8页
Ecology and Environmental Sciences
基金
国家自然科学基金项目（41807082
41771331)
关键词
生物炭
老化方式
二氧化碳
甲烷
氧化亚氮
biochar ageing
ageing method
carbon dioxide
methane
nitrous oxide
