Source profiles of particulate organic matters emitted from cereal straw burnings

Cereal straw is one of the most abundant biomass burned in China but its contribution to fine particulates is not adequately understood. In this study, three main kinds of cereal straws were collected from five grain producing areas in China. Fine particulate matters （PMzs） from the cereal straws subjected to control burnings, both under smoldering and flaming status, were sampled by using a custom made dilution chamber and sampling system in the laboratory. Element carbon （EC） and organic carbon （OC） was analyzed. 141 compounds of organic matters were measured by gas chromatography-mass spectrum （GC-MS）. Source profiles of particulate organic matters emitted from cereal straw burnings were obtained. The results indicated that organic matters contribute a large fraction in fine particulate matters. Levoglucosan had the highest contributions with averagely 4.5% in mass of fine particulates and can be considered as the tracer of biomass burnings. Methyloxylated phenols from lignin degradation also had high concentrations in PM2.5, and contained approximately equal amounts of guaiacyl and syringyl compounds. 13-Sitostrol also made up relatively a large fraction of PMz5 compared with the other sterols （0.18%-0.63% of the total fine particle mass）. Normal alkanes, PAHs, fatty acids, as well as normal alkanols had relatively lower concentrations compared with the compounds mentioned above. Carbon preference index （CPI） of normal alkanes and alkanoic acids showed characteristics of biogenic fuel burnings. Burning status significantly influenced the formations of EC and PAHs. The differences between the emission profiles of straw and wood combustions were displayed by the fingerprint compounds, which may be used to identify the contributions between wood and straw burnings in source apportionment researches.

Constraints on the utilization of cereal straw in lactating dairy cows:A review from the perspective of systems biology

Cereal straw,a human inedible crop byproduct,can be used as a roughage source in ruminants.However,the nutrition density and palatability are very low,limiting its efficient utilization in animal production.This review aims to systematically provide an overview of the limitations of cereal straws,which is crucial for developing new strategies to enhance the efficient use of cereal straws by lactating dairy cows.Evolutionary molecular biology makes it possible to comprehensively understand the limitations of using cereal straw as a roughage source in dairy cows by different techniques,e.g.,multi-omics.Main constraints for utilization of cereal straw and stover in lactating dairy cows include low contents of easily fermented carbohydrates(pectin)and essential amino acids(Met,Phe,and branched-chain amino acids),high content of lignin and silica,and low nutrient digestibility.These cause insufficient supply of the precursors for milk synthesis and result in increased loss of nutrients in feces and urine.Several molecular mechanisms are revealed by multi-omics techniques,including changed amino acid and glucose metabolism,altered rumen microbial composition and function,and differential expression of miRNAs,mRNA,and protein in multi-organs that are associated with milk synthesis.These can be targets of approaches to improve the utilization of cereal straw by dairy cows.In addition,much attention should be given to the efficient countermeasures,including pretreatments by fibrolytic enzymes or steam explosion,dietary formulations such as supplement of pectin,methionine,and branched-chain amino acids,and feeding with other functional feedstuffs,which may improve the feeding and economic value of cereal straw for lactating dairy cows.The newly revealed functional genes(such as BAG3 in the rumen,PC in the liver,CSN1S2 in the mammary gland)and biomarkers(hippuric acid)as well as the integrative signaling and metabolic pathways(phenylalanine metabolism)related to the shortages of cereal straws could be used as nutritional or genetic regulatory targets to improve dairy cow production.

秸秆饲料中纤维素、半纤维素和木质素的定量分析研究

拟定了秸秆饲料中纤维素、半纤维素和木质素的定量分析方法。结果表明:将中性洗涤剂法改为pH2洗涤剂法,更便于过滤;将酸性洗涤剂法改为2 mol/L盐酸洗涤剂法,使ADF中半纤维素含量显著降低,提高了纤维素和半纤维素的测定准确度。与Van Soest方法相比有操作简便、快速,定量准确性高的特点。

秸杆中半纤维素的结构及分离新方法综述

主要介绍了秸秆中半纤维素与木质素,纤维素和蛋白质之间的化学连接方式,以及 碱抽提、碱性过氧化氢抽提和辅助碱抽提等3种新型半纤维素分离方法,综述了近年来农作物 秸秆半纤维素分离方法的研究新进展。

农业秸秆生物质转化利用的研究进展

在分析了农业秸秆转化利用的意义和难点的基础上,从热化学分离、物理化学分离、化学分离及生物分离等方面综述了农业秸秆转化利用的研究现状,并展望了其发展趋势。

谷类秸秆接种瘤胃液的厌氧消化性能和三维荧光光谱特征

在全自动甲烷潜力测试系统中,以瘤胃液为接种物,研究了谷类秸秆(水稻、小麦和高粱)的产酸产甲烷性能和三维荧光光谱特征。结果表明,奶牛瘤胃微生物对谷类秸秆表现出很强的水解酸化能力。经过5 d厌氧消化,水稻、小麦和高粱秸秆单位质量挥发性固体(VS)的总挥发性脂肪酸(TVFAs)产率分别达410. 9、430. 9和472. 0 mg·g-1。谷类秸秆的产甲烷规律符合改进型Gompertz模型。经过55 d的厌氧消化,水稻、小麦和高粱秸秆(以VS计)的甲烷产量分别为66. 29、103. 79和76. 89 m L·g-1。通过三维荧光光谱耦合平行因子分析(PARAFAC)识别溶解性有机物的3个有效荧光组分,3个组分分别为酪氨酸类物质、色氨酸类物质和低分子量腐殖酸类物质。其中,色氨酸类物质的荧光强度与TVFAs浓度呈幂函数关系。谷类秸秆溶解性有机物的腐殖化指数(HIX)经过5 d厌氧消化后降低,而后呈现逐渐上升趋势。

化学改性秸杆原料作高效吸油剂

介绍了秸杆的化学改性方法,油污染处理方法及化学改性秸杆作为高效吸油剂处理溢油污染的优点。并指出了化学改性秸杆研究的未来发展趋势。

不同杂粮作物秸秆厌氧发酵产气特性研究

秸秆的开发与利用对于污染治理和资源循环利用意义重大,其中关于杂粮作物秸秆沼气发酵潜力的研究却鲜有报道。该研究采用批次试验,发酵体积700 m L,总TS为8%,中温(35℃±1℃)条件下探究了玉米、水稻、大豆、谷子、糜子和绿豆6种秸秆厌氧发酵产气特性。结果表明:发酵进行到11 d时,秸秆TS产气率从大到小依次为绿豆131. 0 m L·g^(-1),玉米126. 8 m L·g^(-1),糜子117. 5 m L·g^(-1),谷子114. 1 m L·g^(-1),水稻105. 3 m L·g^(-1)和大豆84. 0m L·g^(-1)。绿豆秸秆甲烷含量最高可达60. 2%,其次分别为糜子秸秆53. 5%,玉米秸秆52. 8%,谷子秸秆50. 0%,水稻秸秆49. 7%和大豆秸秆48. 4%。绿豆秸秆的总有机碳和总氮的减重率最大,分别为43. 25%和21. 77%。绿豆秸秆的纤维素、半纤维素和木质素的降解率最大,分别为15. 43%,9. 86%和7. 24%。各秸秆发酵液C/N分别为玉米29. 04,水稻36. 58,大豆48. 69,谷子35. 90,糜子30. 54和绿豆23. 31。6种秸秆的累积产气量与其总氮减重率,纤维素和半纤维素降解率,C/N显著相关。该研究为不同种类秸秆,尤其是杂粮作物秸秆厌氧发酵提供了一定的数据支撑。

水旱轮作条件下稻麦秸秆腐解规律研究

为探明水稻-小麦轮作条件下稻麦秸秆还田后的腐解规律,对水稻小麦秸秆还田后不同时期的秸秆残余率和氮、磷、钾、纤维素、半纤维素、木质素的累积释放率及平均释放速率进行研究。结果表明,经过腐解(水稻秸杆210天、小麦秸杆120天),水稻和小麦秸秆最终65%以上已腐解;水稻秸秆中氮、磷、钾、纤维素、半纤维素、木质素分别释放60.95%、6.77%、90.58%、38.77%、9.04%、30.97%;小麦秸秆中氮、磷、钾、纤维素、半纤维素、木质素分别释放24.94%、22.01%、93.64%、25.39%、24.19%、39.13%。稻麦秸秆中钾的累积释放率最高,均超过90%。水稻和小麦秸秆中磷的平均释放速率变化不大,氮和钾的平均释放速率高峰均出现在前期,腐解后期呈降低趋势;纤维素、半纤维素、木质素的平均释放速率要高于氮磷钾元素。

基于谷物当量的中国作物秸秆养畜及其节粮潜力估算

中国适宜饲料加工的作物秸秆丰富,秸秆养畜对提高农牧业综合生产能力、提升畜产品安全供给和缓解粮食供需矛盾等方面具有重要意义,文中基于谷物当量定量估算中国秸秆养畜及其节粮潜力,主要研究结论如下:我国适宜饲料化的秸秆资源能量整体呈现逐年增加趋势,至2011年中国秸秆养畜肉类和奶类食品生产潜力分别为2.91×107t和4.80×108t,相当于增加5.76×108t饲料用粮食;同时中国秸秆养畜潜力在地域空间上呈现出地域分异和空间集聚特征,整体上我国各地秸秆养畜潜力由东北部地区向西南部地区逐渐减少,在地域空间分布上表现出集聚特征,其中我国东北部和中部秸秆养畜潜力高丰度区11省市适宜饲料化的秸秆资源占全国总量的69.66%,文中的研究对提高农牧业综合生产能力、推进发展节粮畜牧业和缓解粮食供需矛盾等方面提供重要依据。