【作者】 刘玉学；

【导师】 陈英旭；

【作者基本信息】 浙江大学 ， 环境工程， 2011， 博士

【摘要】 生物质炭是由植物生物质在完全或部分缺氧的情况下经热解炭化产生的一类高度芳香化难熔性固态物质。常见的生物质炭包括木炭、竹炭、秸秆炭、稻壳炭等。生物质炭具有高度稳定性和较强的吸附性能,在全球碳生物地球化学循环、气候变化和环境系统中发挥重要作用。本论文通过对生物质炭特性的系统研究,针对制约我国农业可持续发展的农田土壤养分流失严重和稻田温室气体排放量大等问题,重点开展了生物质炭输入对土壤氮素流失的影响、对稻田土壤温室气体排放的影响以及对水稻生长发育和产量的影响等方面的研究,并就相关机理进行探讨,最后简要提出了今后土壤生态系统生物质炭的研究方向。研究结果为农林废弃生物质炭化资源化和稻田土壤温室气体减排提供了新思路,对实现传统农业向低碳农业发展的结构性跨越,确保我国农业健康可持续发展具有重要现实意义。具体研究结果如下：(1)选择典型性、代表性生物质炭为对象,研究不同生物质炭元素组成、形貌特征、表面基团以及吸附特性。生物质炭的性质受到多种因素的影响,主要包括生物质原料类型、热解过程的环境条件(如温度、供氧状况、湿度等)。炭化温度为600℃时,生物质炭具有较好的综合特性。竹炭和秸秆炭都具有发达的孔隙结构,虽然都以芳环骨架为主,但两者的芳香环结构及含有的含氧官能团有所差异。竹炭的BET比表面积和总孔容均大于秸秆炭,石墨化程度比秸秆炭更高,芳香化更强。秸秆炭的pH、电导率、阳离子交换量、表面酸性基团和碱性基团的数量均大于竹炭。秸秆炭对铵根离子的吸附能力强于竹炭。在改良土壤理化性质、提高土壤肥力方面,秸秆炭比竹炭具有更大的优势。(2)通过实验室土柱淋溶试验,开展生物质炭输入对土壤氮素淋溶特性的影响研究。结果表明,添加竹炭可使土柱0～20 cm土壤溶液NH4+-N浓度显著降低。与只施加氮肥的处理相比,同时施加氮肥和竹炭可使土柱20 cm层土壤溶液NH4+-N累积淋失量在70 d内降低15.2%。添加竹炭使得0-20 cm土壤溶液电导率显著降低。竹炭对土壤中铵态氮具有良好的持留作用,可以起到减少化肥氮素淋溶损失、实现氮素缓释的效果。(3)通过实验室模拟试验,开展了生物质炭输入对淹水稻田土壤温室气体CH4和C02排放的影响研究。研究发现在模拟厌氧条件无外加碳源情况下,稻田土壤CH4排放通量随着生物质炭添加水平的提高而降低,当添加水平为2.5%(w/w)时,竹炭、秸秆炭可使淹水土壤CH4的累积排放量分别降低51.1%、91.2%；而不同添加水平的生物质炭输入对淹水土壤CO2的累积排放量均未产生显著性影响。在以秸秆作外加碳源的情况下,生物质炭输入对淹水土壤CH4和CO2的排放仍然具有一定的抑制作用,但只有在添加水平达2.5%(w/w)时,秸秆炭的抑制作用至培养第49天才呈现出显著性。无论是否外加碳源,秸秆炭对淹水稻田土壤CH4和CO2排放的抑制作用均明显优于竹炭。此外,研究表明竹炭和秸秆炭输入对淹水土壤产甲烷活性起到不同程度的抑制作用,而对土壤甲烷氧化活性均没有产生显著性影响。PCR-DGGE分子指纹图谱分析表明,模拟培养49天后,无论是否添加秸秆,竹炭和秸秆炭输入都未对淹水稻田土壤产甲烷菌和甲烷氧化细菌的种群结构多样性产生显著性影响。(4)通过田间试验研究了生物质炭输入对稻田氮素流失及水稻产量的影响。初步研究结果表明,在未施肥的情况下,添加1%(w/w)生物质炭对稻田氮素流失未产生显著性影响；在施加尿素的情况下,添加竹炭或秸秆炭均能够使稻田田面水和侧渗水NH4+-N、NO3--N和TN浓度呈现降低趋势,但差异性不显著,施加竹炭包膜尿素与常规尿素处理之间亦无显著性差异出现。秸秆炭比竹炭更有利于水稻的生长发育。在不施加尿素条件下,添加1%(w/w)秸秆炭可使水稻产量提高19.9%,即使是在施加尿素的条件下仍可使水稻产量提高11.2%；与秸秆炭相比,’竹炭对水稻产量没有显著性促进作用。更多还原

【Abstract】 Biomass-derived charcoal, also named biochar, refers to the highly aromatic substance remaining after pyrolysis of biomass under complete or partial exclusion of oxygen. It can influence the environment through interactions with climate and geology. Due to its characteristics of high stability against decay and high capability of adsorption, biochar plays a significant role in global climate change, carbon cycle in biogeochemical process and environmental system. Serious nutrient loss from soil and large amount of greenhouse gas emissions from paddy field were two substantial issues which prevent the healthy and sustainable development of agriculture in China. In this thesis, lab and field experiments were carried out to study physi-chemical properties, of biochars. and the effects of different biochars on soil nitrogen loss, methane (CH4) and carbon dioxide (CO2) emissions from paddy soil and rice growth. Furthermore, the mechanisms of effects of biochar on CH4 and CO2 emissions were discussed. In addition, some future research directions about biochar in soil ecosystem were put forward. Results of the study would provide a new approach to the reclamation of biomass residues from agriculture and forestry and a new thought for reducing greenhouse gas emissions from rice paddies. The main results of this thesis are as following:(1) Elemental composition, morphological characteristics, surface functional groups and adsorption proporties of bamboo charcoal (BC) and rice straw charcoal (SC) pyrolyzied at 600℃were investigated in this study. Both BC and SC had high porosity. However, there were main differences in their aromatic structure and oxygen-containing functional groups. Specific surface area and total pore volume of BC were higher than those of SC. While the value of pH, electrical conductivity, cation exchange capacity and the numbers of surface acid and basic groups of SC were much higher. Furthermore, SC also had stronger adsorption capacity to ammonium.(2) Influence of BC on nitrogen retention and leaching characteristic at different soil profile depths were investigated using multi-layer soil columns in laboratory. Results showed that ammonium nitrogen (NH4+-N) concentrations in the leachate of the soil columns under the addition of NH4Cl were significantly different at 0-20 cm layer between the treatments with and without BC amendment. Addition of BC to the surface layer soil can retard the vertical transport of NH4+-N to deeper soil within 70 days, indicated by the observation during the first 7 days at 10 cm and the later experimental period at 20 cm. Application of BC could reduce cumulative losses of NH4+-N via leaching at 20 cm by 15.2% at the end of experiment. Electrical conductivity was significantly reduced in the leachate at 10 cm and 20 cm depth of the soil columns with BC addition. Results indicated that BC amendment could significantly reduce nitrogen losses through leaching and increase the utilization efficiency of nitrogen fertilizer in soil.(3) Effect of biochar on CH4 and CO2 emissions from waterlogged paddy soil with and without rice straw added as an additional carbon source were investigated under laboratory condition. Results indicated that adding rice straw significantly increased CH4 and CO2 emissions from the paddy soil. However, CH4 and CO2 emissions could be significantly reduced with the amendment of biochar. CH4 emissions from the paddy soil amended with BC and SC at high level were reduced by 51.1% and 91.2%, respectively, compared with those from the unamended soil. CO2 emission from the waterlogged paddy soil was also reduced with the addition of biochar over a 49 d incubation. SC was more effective than BC in reducing CH4 and CO2 emissions from paddy soils whether with additional carbon source or not. Methanogenic activity in the paddy soil decreased with increasing rates of biochar added; while, the methanogenic archaeal communities in the paddy soil amended with biochar remained unchanged at the final stage of the experiment.(4) The effects of biochar input on nitrogen loss from paddy soil and rice yield were studied under field condition. Initial results suggested that nitrogen losses through effluent and lateral seepage were not significantly influenced by the amendment of biochar when no fertilizer was added. However, the concentrations of NH4+-N, NO3--N and TN of surfacewater and lateral seepage water in the rice paddy showed reducing potential with 1% (w/w) biochar amendment when urea was applied, although there were no remarkable differences. On the other hand, however, SC was much effective in improving rice growth than BC. Rice yield was increased by 19.9% with 1% (w/w) SC amendment compared to that without biochar under no fertilizer condition. While that was 11.2% under urea-added condition. Whereas the boosting effect of BC on rice yield showed less.substantial as compared with SC.更多还原