添加生物炭对秸秆还田土壤VOCs释放和微生物多样性影响研究

发布时间：2018-01-10 16:31

  本文关键词：添加生物炭对秸秆还田土壤VOCs释放和微生物多样性影响研究　出处：《安徽师范大学》2016年硕士论文　论文类型：学位论文

  更多相关文章： 秸秆还田 挥发性有机物(VOCs) 土壤微生物多样性 生物炭 排放通量 PCR-DGGE

【摘要】：秸秆还田是我国常用的一种秸秆处理手段,秸秆还田分解过程中会释放大量挥发性有机污染物(VOCs)。VOCs是近地面大气臭氧和二次有机气溶胶的重要前体物,同时对臭氧层空洞、全球辐射平衡和气候变化具有重要贡献,因此很有必要寻求一种途径来控制秸秆还田土壤VOCs排放。生物炭由于其自身的结构特性,对土壤CO_2、N2O和CH4等气体具有显著减排效应,而有关于生物炭添加对秸秆还田土壤VOCs减排是否可行目前还未见报道。秸秆还田分解主要是一个微生物参与的代谢过程,而生物炭施入到土壤中会对土壤微生物多样性产生影响,因此研究生物炭添加对秸秆还田过程中微生物群落结构和多样性的变化能更好地探究生物炭对秸秆还田土壤VOCs释放的影响机理。本研究以安徽省芜湖市的农田土壤和小麦秸秆为对象,设置添加(SBW)和未添加(SW)生物炭秸秆还田土壤两个处理,研究分析秸秆还田过程中VOCs的组成特征和排放通量、土壤微生物数量、细菌群落结构变化等,探讨添加生物炭对秸秆还田土壤VOCs排放的影响机理。本研究的主要结论如下:(1)秸秆还田过程中释放出来的VOCs主要包括非甲烷碳氢化合物(NMHCs)、含硫化合物(VSCs)和含氧化合物(OVOCs)三类物质。生物炭添加显著增加了VOCs排放量,特别是OVOCs排放量,但显著降低了VSCs排放量。SW和SBW处理中VOCs累积排放量分别为7.29 mg kg-1和36.5 mg kg-1,其中OVOCs(酮类、醇类、醛类、酮类和酯类,共33种)排放量分别为6.95 mg kg-1和36.2 mg kg-1,占对应两个处理中VOCs总排放量的95.3%和99.1%;NMHCs(C2-C5的5种烷烃和5种烯烃)排放量分别为211μg kg-1和256μg kg-1;VSCs包括二甲基硫醚(DMS)、二甲基二硫醚(DMDS)、二甲基三硫醚(DMTS)和二硫化碳(CS2)四种,排放量分别为132μg kg-1和81.4μg kg-1。对于单种VOCs,SW处理中丙酮排放量最高,占VOCs总累积排放量的45.3%,其次是乙醇、2-丁酮、2-戊酮、异丙醇、2-丁醇和乙醛,这7种物质共占VOCs总排放量的91.7%;SBW处理中,丙酮也是最主要的VOC,占VOCs总排放量的38.3%,其次是2-戊酮、2-丁酮、乙醇、异丙醇、2-己酮和2-庚酮,这7种物质共占VOCs总排放量的95.9%。(2)秸秆还田过程中,两个处理中VOCs排放速率随时间发生明显变化。SW处理中10种NMHCs分别0-24天和24-56天两个时间段内出现1-2个峰值,四种VSCs基本在前30天释放,并在12天左右达到峰值,大部分OVOCs基本在前30天释放,并在20-30天范围内出现峰值。SBW处理中10种NMHCs一般在0-17天和24-56天两个时间段内出现1-2个峰值,DMS、DMDS和DMTS均在17天达到排放峰值,且均在前34天释放,CS2则在4-17天和24-44天时间段内各达到一个峰值,而OVOCs在0-24天和34-56天两个时间段内出现1-2个峰值。(3)DGGE谱图和多样性分析结果表明,生物炭添加增加了秸秆还田土壤细菌DGGE图谱条带位置和灰度值以及均匀度的变化,但两个处理土壤细菌群落Shannon-Wiener指数和丰富度没有显著差异(P0.05)。聚类分析结果表明,SBW处理土壤细菌群落聚为5类,SW处理土壤细菌群落可聚为6类。DGGE条带测序和结构分析结果表明,生物炭添加导致秸秆还田土壤中Actinobacteria和Nitrospira消失和Spirochaetes、Gemmatimonadetes、Chloroflexi和WS3出现,以及Firmicutes和Proteobacteria所占比例升高和Acidobacteria和Bacteroides所占比例降低。(4)两个处理中各类VOCs排放量与各微生物指标(微生物菌落信息、微生物碳量,CO_2,微生物数量)呈现不同程度的相关性,表明微生物活动对秸秆还田过程中VOCs释放具有重要影响。VOCs排放量与土壤化学元素的相关性研究结果表明VOCs释放与土壤理化性质也有一定联系,也间接反应了与微生物活动的关系。
[Abstract]:Straw is commonly used in China, a straw processing means, straw decomposition process will release a large amount of volatile organic compounds (VOCs).VOCs is an important precursor of ozone in the atmosphere near the ground and two secondary organic aerosol, and the hole in the ozone layer, global radiation balance and climate change has important contribution, so it is necessary to to control the straw returning soil VOCs emissions to seek a way. Biochar because of their structural characteristics, the soil CO_2, N2O and CH4 gas has significant reduction effect, and a straw biochar addition on soil VOCs emission reduction is feasible at present has not been reported. The straw decomposition is mainly a microorganism in the metabolic process, and biochar applied to the soil will affect the soil microbial diversity, so the study of biochar addition on microbial community structure in the process of straw The influence mechanism and diversity can better explore the biological carbon release in straw amended soil VOCs. In this study, Anhui city of Wuhu province farmland soil and wheat straw as the object, adding (SBW) and (SW) without the addition of biochar straw two soil treatment, analysis and study of composition characteristics and emission the fluxes of VOCs straw in the process, the quantity of soil microorganisms, bacterial community structure changes, to explore the influence of straw biochar soil VOCs emission mechanism. The main conclusions of this study are as follows: (1) release the straw in the process of VOCs mainly include non methane hydrocarbons (NMHCs), sulfur compounds (VSCs) and oxygen containing compounds (OVOCs) of three kinds of material. The biochar addition significantly increased VOCs emissions, especially OVOCs emissions, but significantly reduced the cumulative emissions of VSCs.SW and SBW VOCs in the treatment of emissions were 7.2 9 mg kg-1鍜，

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