用δ13C方法研究玉米秸秆分解期间土壤有机质数量动态变化

通过室内培养实验 ,应用δ1 3C方法研究了玉米秸秆分解期间 ,土壤中胡敏酸 (HA)和富里酸 (FA)数量的动态变化。结果表明 :培养期间 ,新加入的玉米秸秆以及原土有机C都减少 ,但后者分解速度较慢。培养初期 ,FA的形成速度大于HA ;随培养时间延长 ,FA转化为HA或相互转化。原土有机质中 ,HA、FA也发生了相互转化 ,但与新形成的HA、FA相比转化速度较慢。用δ1 3 C方法研究短期培养 (几个月～几年 )条件下新加入有机质在土壤中的分解动力学是可行的。     

施用猪粪对棕壤胡敏酸和富里酸热力学参数的影响

应用Vodyanitsky提出的方法，根据元素组成数据，计算了施用猪粪对棕壤胡敏酸(HA)、富里酸(FA)热力学参数的影响。结果表明，HA、FA的形成都是自发进行的放热反应；与HA相比，FA的能态较低，分子结构有序度和热稳定性较高；FA在土壤中比HA更容易形成。施用猪粪后，HA、FA的能态降低，分子结构有序度和热稳定性也降低，形成的自发性减弱且放热量减少，这些与它们元素组成的变化有关。     

土壤中水溶性有机质的结构特征及其与富里酸、胡敏酸的比较

采用元素分析、1HNMR和FTIR研究了黄泥土中水溶性有机质组成及结构特征,并与富里酸、胡敏酸进行比较。结果表明:胡敏酸含有大量的芳香族不饱和物质,烷基链烃多,支链长;富里酸以含有大量的羧基为主要结构特征;水溶性有机质主要由碳水化合物组成,含有大量的羟基,芳香族不饱和物质少。     

土壤胡敏酸与富里酸热力学稳定性及其驱动因素初步研究

从过程考虑,腐殖质的形成和转化主要是微生物主导的生物化学过程,但就其始态和终态的能量水平变化而言,是热力学稳定性问题。在土壤中,影响腐殖质的形成转化的因素很多,如黏粒含量和类型,植被和微生物状况,土壤湿度、温度和空气组成,土壤溶液的化学组成、浓度、酸度和氧化还原状况等。但从热力学角度,为了计算反应平衡常数(logKR)和吉普斯生成自由能(ΔGfθ),如果将温度设为25℃,我们可以将土壤条件诸多因素简化为水活度([H2O])、氧分压(PO2)和二氧化碳分压(PCO2)这3个参数。之所以简化为这3个参数,因为任何有机成分均是由含有这3种元素的物质形成的,最终又均可以分解为含有这3种元素的H2O和CO2。本文按照上述新思路,以黑土为例探讨了胡敏酸(HA)、富里酸(FA)形成转化的驱动因素和热力学稳定性的研究方法,用元素组成-土壤条件参数法计算HA、FA的logKR和ΔGfθ及热力学稳定性范围。同时通过土壤添加有机物料的模拟培养实验研究了氧气和二氧化碳等单因素对HA和FA数量积累的影响。结果表明,黑土HA和FA的元素组成分子式分别为nC21H21O9N和nC24H33O17N。FA在缺氧、多水和高浓度二氧化碳条件下较稳定;HA则相反。培养实验中,高二氧化碳和低氧气浓度处理使FA与HA的相对比例增加。这一研究方法和结果将有助于解释和推测土壤腐殖质组成的空间变异规律,指导土壤肥力、土壤固碳的调控实践。     

几种胡敏酸和富里酸分子结构模型的三维可视化与特性研究

针对已提出的几种胡敏酸和富里酸的二维分子结构模型,应用HyperChem软件转换为三维结构并进行几何优化,计算了这些三维模型的能量以及定量构效关系(QSAR)参数。结果表明:几种模型在三维结构和特性上都各不相同,这为从空间角度更直观地认识腐殖物质的分子结构提供了可能性。     

玉米秸秆腐解过程中形成胡敏酸的组成和结构研究

采用化学方法和谱学方法对玉米秸秆腐解生成胡敏酸（CCSR HA）的组成和结构进行了研究.结果表明,CCSR HA的碳组成可分成三个部分：脂肪族碳、芳香族碳和羧基碳,它们的含量分别为59.62%、26.94%和13.44%.CCSR HA主要的官能团包括羟基、烷基、羧基、酰胺基、苯环、烷氧基及碳水化合物结构,木质素残体是其骨架,碳水化合物结构或类糖结构及烷基片段是其主要组成单元.其类型属于Rp型胡敏酸.未腐解的玉米秸秆本身就含有类胡敏酸物质（OCSR HA）,OCSR HA和CCSR HA的官能团组成上有一定差异,后者结构中,甲基、亚甲基、次甲基、醚键官能团和酚羟基的含量降低,而酰胺成分、游离的羧基、甲氧基、碳水化合物组分相对含量升高,脂族性升高,芳香性降低,芳香度由初始的42.19降至腐解后的29.97,并且与无机物质的结合能力增强.就元素组成的变化看,CCSR HA中C和H元素的含量趋于降低,而N和O元素的含量趋于升高.CCSR HA同土壤胡敏酸相比,糖类结构含量较高,并且以片段的形式与水解木质素残体相连.羧基含量较低,但以不同的连接方式存在着.     

不同CO2浓度对玉米秸秆分解期间土壤腐殖质形成的影响

以往人们较多的研究了土壤有机碳与温室气体的源、汇关系问题,却很少研究温室气体对土壤有机碳本身分解转化和各组分性质的影响。为了探讨CO2浓度升高对腐殖物质形成转化的作用,本文通过室内人为高浓度CO2的培养试验,用腐殖质组成修改法研究了玉米秸秆分解期间（1~180d）土壤总有机碳（TOC）、水溶性物质（WSS）、碱提取腐殖物质（HE）、胡敏酸（HA）和胡敏素（HM）数量的动态变化规律及不同CO2浓度对有机碳各组分形成与转化的影响。结果表明：玉米秸秆分解期间,“新形成”的净TOC逐渐降低,净HE表现为先增加而后下降的趋势,HM的绝对数量逐渐下降。可提取腐殖物质中HA的比例（PQ）先增加后下降,最终趋于平稳,说明最初富里酸（FA）的形成速度大于HA,随培养时间的延长,FA和HA经历了一段相互转化的过程,最终达到动态平衡。30%CO2浓度（V/V）处理的TOC、WSS、HE和HM数量明显高于3%CO2浓度处理和正常CO2浓度（0.0375%）处理,其中WSS和HM反应更为敏感。但3%CO2浓度处理与正常CO2浓度处理的差异不明显。可提取腐殖物质的PQ的顺序是30%CO2浓度处理〉3%CO2浓度处理〉正常CO2浓度处理,说明CO2浓度增加更有利于FA而不利于HA的形成和稳定。     

铁、锰、铝氧化物固体吸附剂对胡敏酸和富里酸吸附机理研究

研究了Fe2O3、MnO2或Al2O3固体吸附剂对胡敏酸和富里酸的吸附机制和影响因素。结果表明:相同pH下,Fe2O3、MnO2或Al2O3固体吸附剂对腐殖酸的吸附量随着腐殖酸(胡敏酸HA和富里酸FA)有机碳浓度的增加而增加;不同pH下,对HA的吸附量依照pH3·0>pH5·0>pH7·0的顺序递减。相同pH下,随着HA有机碳浓度的增加,三种固体吸附剂对HA的吸附百分率减小。相同pH下,三种固体吸附剂对FA的吸附百分率呈单峰形,随着酸度的降低,峰位向添加的有机碳低浓度处迁移。吸附量用Langumuir方程拟合能得到极显著相关的方程,在相同pH下,三种固体吸附剂吸附HA的最大吸附量Smax和吸附亲和力常数K小于FA,而标准自由能变ΔGmo却略大于FA;298·2K温度下,三种固体吸附剂吸附胡敏酸和富里酸的ΔGmo<0,表明在等温等压不做非体积功情况下吸附是自发进行的反应。     

添加玉米秸秆培养对土壤团聚体胡敏酸数量和结构特征的影响

利用湿筛法进行土壤团聚体分组(>2、2～0.25、0.25～0.053、<0.053 mm粒级),研究了其添加不同用量玉米秸秆,25℃恒温室内培养对团聚体中胡敏酸数量和结构特征的影响。结果表明:添加玉米秸秆培养后,土壤团聚体2～0.25 mm和>2 mm粒级成为优势粒级,平均含量分别占51.41%和34.12%,其全碳含量为10.15～25.74 g kg-1,胡敏酸(HA)绝对含量为4.06～5.79 g kg-1,明显高于对照CK的9.79～10.48 g kg-1和3.70 g kg-1,并随玉米秸秆用量的增加而增大;各处理胡敏酸C/H及高温/中温比值均低于CK处理,并随玉米秸秆用量的增加逐渐减小,说明随玉米秸秆用量的增加使HA分子缩合度降低,结构趋于简单化。     

秸秆还田条件下内陆盐碱土腐殖质的动态变化

采用室内培养试验的方法,研究了秸秆加入条件下内陆盐碱土的腐殖质及其组分(胡敏酸、富里酸)的动态变化。结果表明,在秸秆腐解过程中,盐碱土腐殖质、富里酸、胡敏酸含量均呈现持续上升趋势,分别平均增加了112.5%,269.54%和92.9%富里酸的含量明显高于胡敏酸的含量,是胡敏酸含量的约3~10倍。土壤的HA/FA(腐殖酸/富里酸)呈现出先增长后降低的趋势,并且在90d时达到平均最高值(0.283)。尿素添加量7.2g的处理土壤腐殖质含量在0.19%~0.38%,该处理秸秆分解的速率最快。土壤腐殖质和富里酸随着尿素含量梯度的增加呈现先上升,后下降,再上升的趋势,且分别平均增加了46.7%和55.3%胡敏酸的变化趋势与腐殖质相反,平均减少了14.3%HA/FA呈下降趋势,但下降趋势不明显。     

黑土无机纳米微粒对玉米秸秆腐解水溶性产物的影响

通过秸秆腐解试验研究黑土无机纳米粒子对玉米秸秆腐解过程中水溶性化合物含量和C、N元素组成的影响。结果表明:在腐解初期,纳米粒子处理的水溶性有机化合物(WOM)、水溶性小分子有机化合物(WLOM)和水溶性胡敏酸(WHA)的含量分别高出对照21.9%,2.8%,18.3%,随着腐解进行,黑土无机纳米粒子显著抑制了三者含量;在腐解的前期,黑土无机纳米粒子对水溶性有机化合物(WOM)总C量无显著影响,降低了WHA的C含量,提高了WLOM的C含量。在腐解中后期,黑土无机纳米粒子降低了水溶性产物(WOM、WHA、WLOM)的C含量。在整个腐解时期,黑土纳米粒子降低了WOM和WHA中的N含量,而对WLOM含N量无显著影响。     

Physiological Effects of Different Combinations of Humic and Fulvic Acid on Gerbera

Flower quality loss, especially short postharvest life, is a major problem in gerbera production. An experiment was conducted to determine how different combinations of humic substances (HS) affect gerbera. Humic acid (HA) and fulvic acid (FA) applied to nutrient solutions in six combinations including control (nutrient solution only), 80 mg L^?1 HA + 20 mg L^?1 FA, 60 mg L^?1 HA + 40 mg L^?1 FA, 40 mg L^?1 HA + 60 mg L^?1 FA, 100 mg L^?1 FA, and 50 mg L^?1 FA. The HS application enhanced root architecture, nutrient content, number of harvested flowers, and vase life. Fifty (50) mg L^?1 FA extended vase life by 8 days and increased flower number (72.9%). Results suggest that HA and FA (especially 50 mg L^?1 FA) can improve quality and quantity of gerbera through improving root architecture, leading to enhanced nutrient uptake and possibly affecting hormone-like activities. It seems that using low concentrations of FA may be part of a solution in improving gerbera flower quality.     

Utilization of Compost Increases Organic Carbon And Its Humin,Humic and Fulvic Acid Fractions In Calcareous Soil

Organic carbon sustainability in a gravelly calcareous soil is a great challenge under the humid conditions of south Florida. The beneficial effects of compost utilization on soil fertility prompted an investigation on (i) accumulation of total organic carbon and (ii) the soil organic carbon (SOC) in humin, humic acid (HA) and fulvic acid (FA) fractions in a gravelly calcareous soil amended with composts or inorganic fertilizer. In 1996 and 1998, compost from municipal solid waste (MSW) (100% MSW), Bedminster cocompost (75% MSW and 25% biosolids) and biosolids compost (100% biosolids) at 72, 82.7 and 15.5 Mg ha^?1, respectively, were each incorporated in soil beds and inorganic fertilizer (6-2.6-10) NPK at 2.8 Mg ha^?1. A control (no amendment) treatment was also included. Total organic carbon and various fractions of soil organic carbon were determined in two depths (0-10 and 10-22 cm) for both soil particles (< 2mm) and pebbles (> 2mm). Inorganic and organic soil amendments had decreased soil pH and increased soil electrical conductivity (EC) 19 months from initial application. Total organic carbon contents in soil particle were 4-, 3-, and 2-fold higher in MSW compost, Bedminster cocompost and biosolids compost treatments, respectively, than those in fertilizer treated or non-treated soils. MSW compost increased total organic carbon in pebbles by 4- and 3-fold in the 0-10 and 10-22 cm deep layers, respectively, more than other treatments. The soil organic carbon accumulation decreased with depth in all treatments in soil particles, but did not in pebbles. Amending soils with MSW compost significantly increased the organic carbon in humin, HA and FA fractions more than those treated with inorganic fertilizer or non-amended. MSW compost has a potential to be used as a soil amendment to increase and sustain the organic carbon in calcareous soils of south Florida.     

Effects of Clay Surfaces on the Adsorption and Biological Decomposition of Proteinaceous Components of Fulvic Acid

Shaking of an aqueous fulvic acid (FA) solution with montmorillonite at pH 2.5 at room temperature, removed about 43 % of the FA fraction containing proteinaceous components. About 65 % of this fraction was adsorbed reversibly in interlayers, 20 % on external surfaces and 15 % was adsorbed irreversibly. The relative molar distribution of the amino acids (after hot acid hydrolysis) in the original FA, the FA fraction adsorbed in clay interlayers and in the FA fraction not adsorbed by montmorillonite was relatively uniform, indicating that clay interlayers were relatively inefficient for separating proteinaceous constituents from main structural FA components. External clay surfaces, however, appeared to adsorb peptides and/or proteins that differed qualitatively from those adsorbed on internal clay surfaces. Five successive treatments with fresh clay showed that only 61 % of the FA fraction containing proteinaceous components could be adsorbed. The original FA and all fractions separated from it by montmorillonite were able to support microbial growth without the addition of an external N source. The rate of biodegradation decreased when the FA was complexed with montmorillonite.     

冬小麦-夏玉米轮作制度下腐植酸氮肥去向与平衡

为促进新型肥料的应用,减少环境污染,提高玉米、小麦产量,通过同位素示踪技术研究新型腐植酸氮肥对玉米和小麦产量、氮肥吸收利用、氮肥在土壤中分布、氮肥损失以及土壤氮素盈亏的影响。结果表明:脲基活化腐植酸氮肥和常规掺混腐殖酸氮肥可显著增加玉米和小麦产量,提高氮肥利用率,增加氮肥残留量,减少氮肥损失,增加土壤氮素盈余,增加土壤氮素矿化,增加作物对土壤氮素的吸收,其中脲基活化腐植酸作用效果更加明显。脲基活化腐植酸氮肥和常规掺混腐殖酸氮肥与普通尿素相比,玉米产量分别增加20.6%和9.8%,小麦产量分别增加50.5%和19.2%;玉米季氮肥利用率分别提高5.8%和3.4%,小麦季分别增加22.7%和8.6%;玉米季氮肥损失率分别减少18.3%和10.9%,小麦季分别减少20.2%和6.3%;玉米季氮肥残留率分别增加12.5%和7.5%,小麦季分别减少2.7%和2.2%。施用腐植酸氮肥能改善氮素在土壤中的分布,满足作物根系需肥特性。     

Carbohydrates as Chemical Constituents of Biowaste Composts and their Humic and Fulvic Acids

The decomposition of organic matter of source-separated biowaste during composting was followed during 18 months. Compost samples were fractionated into three parts: (i) hot water soluble extract (HWE) (ii) bitumen fraction and (iii) humic substances (humic acids (HA) and fulvic acids (FA)). Original compost samples and the HA and FA fractions were hydrolyzed with sulfuric acid for hexoses and pentoses. Quantitative spectrophotometric and qualitative GC/MS analyses of monosaccharides as trimethylsilyl ethers of the corresponding alditols were carried out.

During composting, the amount of HA in the organic matter of the compost increased, the amounts of HWE and bitumen decreased and the amount of the FA fraction changed only a little. Carbohydrates were found to be important constituents of biowaste composts and their HA and FA fractions. Elemental analysis (C, N and H) of compost and HA samples showed an increase in the C:H ratio and in unsaturation of compounds during composting. The decrease in the C:N ratio was marginal.

The amounts of hexoses and pentoses in original compost samples and the HA and FA fractions decreased during composting. The sugar alcohols erythritol, xylitol, L-arabitol, ribitol, L-rhamnitol, L-fucitol, D-mannitol, D-glucitol and galactitol were identified in both the HA and FA fractions. 2-Deoxy-D-erythro-pentitol was identified in one HA fraction and inositol in two FA fractions. An analysis of gas chromatographic data for relative abundances showed that, in every sample except one and in every stage of composting D-glucitol was the main sugar alcohol. In general, the relative amount of D-glucitol decreased during composting, while the relative amounts of all other sugar alcohols increased.

As chemical indicators of compost maturity, carbohydrates would appear to be a important group of compounds. Most informative as a general indicator would be the ratio of the amount of HA to the amount of organic matter in the total compost samples.

According to our studies, the carbohydrates in composts are covalently bound to the structures of FA and HA. Carbohydrate determination clearly deserves more attention in the structural elucidation of FA and HA.     

玉米秸秆整株深埋还田技术研究

介绍在小麦、玉米一年两熟条件下,玉米秸秆直接还田的一种全新方法——玉米秸秆整株深埋还田技术(以下简称玉米整株还田),所需配套机具及操作工艺、技术要点和3年的试验结果。研究结果表明整株还田,秸秆经过一年的腐解,腐解率达90%以上,土壤有机质年均增加0.11%。玉米整株还田耕深20cm,秸秆在土壤8cm深度以下秸秆覆盖率达95%以上,能够保证冬小麦播种质量,小麦播种出苗后基本苗及分蘖测定分别比粉碎还田(对照)增加23株和0.2个。小麦生育期干物质和千粒重分别增加8.95%和1.33%,小麦产量提高3.81%,比秸秆堆沤还田和粉碎还田投入分别减少65.7%和50%。玉米整株还田具有省工、省力、省时、节能、增产增收的良好效果。目前已在河北省栾城县大面积推广应用     

小麦和玉米秸秆热解反应与热解动力学分析

为了对生物质快速热解液化设备进行分析和计算，该文用热重、差热分析仪分别对小麦和玉米秸秆在不同升温速率下进行了热分析研究。结果表明：小麦和玉米秸秆的热解特性基本一致，热解过程可以用同一种模型描述；随升温速率的提高，热解最高速率时的温度和热解最高速率明显提高。分析了小麦和玉米秸秆热解反应过程，提出了平行一阶反应动力学模型并计算出模型中各参数，将该模型的计算结果、现有一阶反应模型的计算结果分别和试验数据进行了对比，结果表明，平行一阶反应模型的准确程度比现有一阶反应模型有很大的提高。