农林废弃物热解的试验研究

介绍了用于生物质热解的试验装置及试验方法，研究了温度、加热速率等因素对木屑、稻壳等农林废弃物生物质热解产物的产率及其质量的影响。试验结果表明，两种不同生物质热解产物得率的变化规律基本一致。热解温度控制在４００～５００℃时，热解油产率最大。热解温度越高，则炭产量越少；温度大于５００℃时，热解气为中等热值可燃气，其热值大于１０ＭＪ／ｍ^３。测试结果还表明，常规热解条件下的生物质热解表现为三阶段反应特点     

生物质快速热裂解反应温度对生物油产率及特性的影响

以木屑为原料，在自制的小型流化床上，研究了生物质快速热裂解反应温度对生物油的产率、含水率、密度、黏度及成分的影响。结果表明，在475℃，500℃和550℃三种热裂解温度中，以500℃的平均生物油产率最高，为58.74%(w/w)。三种热裂解温度下，生物油的含水率分别为42.5%、46.0%和40.7%，生物油的密度分别为1140、1148和1151 kg/m³，运动黏度分为4.51 cSt、3.87 cSt和4.73 cSt。热裂解温度增高时，生物油的密度略有增加，含水率和运动黏度未见有规律变化，并且，运动黏度随含水率的增加而减小。热裂解温度对生物油的主要化合物成分相对含量有一定影响，但影响不明显，生物油中化合物几乎都是含氧的不饱和烃类衍生物，碳原子数在2～10之间，温度升高有利于糠醛、大多数苯酚类化合物生成，不利于乙酸的生成。该研究为生物油的生产与应用提供了参考。     

厌氧消化残渣与低阶长焰煤共热解特性

为提高厌氧消化废弃物的能源效率和实现低阶煤的清洁高效利用,该文通过采用长焰煤和木质纤维素生物质厌氧消化残渣(沼渣)共热解方法,利用热重分析仪、固定床热解反应器等考察长焰煤和沼渣的共热解特性,深入研究温度对等比例混合的长焰煤和沼渣共热解产物特性的影响。热重结果表明,长焰煤和沼渣实际热重曲线与计算曲线存在差异,二者共热解存在明显协同效应。共热解试验结果表明：随着温度的升高,热解焦油产率呈先增高后降低趋势。当温度从400 ℃增加到500 ℃时,焦油产率从9.23%增加到12.12%;进一步升到温度到700 ℃,焦油产率降低到9.30 %。H2、CO产率随着温度的升高先减少后增加,而CH4产率随着温度先增加后降低,热解气体的热值在600 ℃达到最大值15.33 MJ/m3。GC-MS结果表明,600 ℃时的热解油中单、双环芳烃相对含量高,含氧较少,共热解油中的化合物由于协同效应的存在有明显的提质。厌氧消化残渣与长焰煤的共热解存在协同效应,能够提升焦油产率与芳构化能力,二者共热解产物质量油、气均有显著提升。     

热解温度对生物质炭碳保留量及稳定性的影响

以核桃壳为生物质炭生产原料,研究热解温度(200~700℃)对生物质炭产率、元素组成、表面官能团分布及其稳定性的影响,以期探明生物质炭基本性质随热解温度变化的规律,为全面了解生物质炭固碳减排效果提供理论参考。结果表明,生物质炭的C含量随温度升高而增加,H和O元素含量却随温度升高而降低。此外,生物质炭的H/C和O/C随着温度增加而减少。生物质炭的产率及碳保留量随着温度的升高而降低。红外光谱分析结果表明,经过热解核桃壳原材料分子中所含的-C-O和O-CH3基团消失,随着热解温度升高,生物质炭中的烷烃基团-CH逐渐减少,芳香化程度逐渐升高。500℃制备生物质炭的K2Cr2O7和KMn O4氧化碳损失量均最低,分别为10.4%和1.66%。相关分析表明,生物质炭的产率、碳保留量及稳定性与热解温度之间均具有显著相关关系。     

反应温度和停留时间对纤维素水热解产物理化特性的影响

为了解纤维素在水热降解过程中产物的理化特性及其形成机制,该文对生物质主要组分—纤维素的水热降解特性进行了系统地研究,全面分析了反应温度和停留时间对纤维素水热产物分布的影响,并从产物的化学结构入手,对纤维素水热解机理进行了探索。随着温度的升高,重质油产率在250℃时达到最大,重质油组分变得复杂,焦炭产率逐渐降低。随着停留时间的延长重质油产率呈现先增加后降低的趋势,焦炭产率变化趋势较小,然而通过对焦炭的热重、红外、元素、电子扫描显微镜和X射线光电子能谱仪分析表明停留时间的延长可以提高焦炭的化学官能性,这为生物质水热机理的研究提供了依据。     

玉米芯和桉木的低温热解特性

为实现生物质资源的分级综合利用,该文采用热重分析仪和裂解气质联用仪进行了对玉米芯和桉木低温热解特性的研究。试验结果表明不同生物质原料低温快速热解产物有明显差异,玉米芯的低温快速热解产物主要有乙酸、2,3-二氢-苯并呋喃和2-甲氧基-4-乙烯基苯酚,而桉木的产物主要是乙酸、糠醛和5,6-二氢-4-羟基-吡喃-2-酮。生物质低温快速热解产物种类较少,分布较为集中,玉米芯和桉木的酸类、呋喃类,桉木的吡喃类热解产物相对含量随温度上升而降低。生物质低温热解能有效分解其半纤维素,这为降低中温热解油的酸性和水分提供了理论指导。     

NH3气氛下温度对生物质富氮热解产物特性的影响

生物质热解转化为高值产品是生物质利用的重要发展方向,在热解过程中引入外源氮素形成富氮热解,具有制备高值含氮产品的潜力。该文以NH_3为外源氮素,研究了不同热解温度对木屑和玉米秆富氮热解过程和产物特性的影响,探讨了含氮物质的形成机理,为生物质转化为高值产品提供理论依据。采用多种方式(气相色谱-质谱联用、元素分析、漫反射傅立叶变换红外光谱、X射线光电子能谱等)对热解产物特性进行了分析。结果表明,随着热解温度的升高,焦炭产率逐渐减小,热解油产率先增加后减小,550℃达到最大值。热解油中含有大量的胺态氮有机物(甲胺类和丙胺类等)和含氮杂环类物质(吡咯类和哌啶类等),以及少量的腈类。热解焦炭的含氮量随着温度升高而增加,焦炭表面存在大量含氮官能团C=N、N-COO、C-N和N-H等。含氮官能团的存在形式主要有吡啶-N、吡咯-N和酰胺-N,随着热解温度的升高,酰胺-N含量逐渐降低,而吡啶-N含量迅速增加,高温下主要为吡啶-N和吡咯-N。     

生物质快速热裂解主要参数对产物产率及其分布的影响

在生物质喂入率为0.8～2.0 kg·h^-1的流化床上以木屑为原料进行了快速热裂解试验，系统研究了木屑热裂解过程中的流化床反应器温度、生物质粒径和气相滞留期三个主要参数对热裂解产物产率的影响。结果表明，当反应器温度在450～600℃之间变化时，在500℃条件下，生物油产率最高，其值为53.33%，而木炭及不可冷凝气体产率分别为8.97%和37.70%。当温度为500℃，木屑粒径在0.90 mm以下时，粒径在0.45～0.60 mm范围内的生物油产率最大，达到58.23%，这时木炭产率为8.23%。对粒径小于0.20 mm的木屑在温度500℃，气相滞留期0.80, 1.20, 1.50 s三个量级上的热裂解表明，气相滞留期为0.80 s时，生物油产率达到最大值为62.60%。但是，当气相滞留期较长时(1.50 s)，生物油产率稍有下降。生物油是极性有机物与水的可溶混合物。因此，木屑快速热裂解生产液体燃料具有较大的潜力。     

工业木质素的热裂解试验研究

本文研究了木薯水解剩余木质素在N2氛围下的TG和DTG曲线,以及在不同升温速率下热裂解产物的组成随温度的变化情况。试验结果表明,在290~430℃之间热裂解速率最快;在400~800℃之间时,焦炭产量随着温度的升高而降低,焦油产量首先会随着温度升高而增加,在达到一个最大值后,随着温度的进一步升高,部分挥发分的二次热解会使焦油产量降低,气体产量随着温度的升高而增加,H2、CO、CH4和CO2等组分也随着温度的升高而有相应的变化;快速热解在600℃以下有利于焦油和焦炭的生成,在600℃以上有利于气体的生成。通过GC—M S分析发现焦油中的组分主要是苯酚类化合物。     

热解温度对回转窑玉米秸秆热解产物理化特性的影响

针对北方农业秸秆废弃物产量巨大且无法全部还田导致丢弃和露天焚烧现象激增等问题,该文通过搭建小型回转窑生物质热解装置考察不同热解温度下秸秆热解特性,分析主要产物的产率、元素组成等理化特性指标。结果表明:回转窑内热解温度的增加提高了热解液相产物产率和热解水产率,焦油产率呈先增加后降低趋势。与此同时,热解气总体积逐渐增加,H2含量和CH4含量也有所提高,生物炭产率和热值有所降低。当热解温度从400℃增加至700℃时,焦油产率从12.21%增加至21.70%;当温度进一步增加至800℃时,焦油产率降低至20.13%;相应的焦油热值从400℃时的19 974.0 kJ/kg逐渐增加到800℃时的21 710.0 kJ/kg。高热解温度加快热解过程中的热传递,加剧生物质大分子所含的羟基、羰基等含氧官能团的分解并促进挥发物的产生,进而提高了热解液体产物、热解水和焦油产率。过高的加热温度会加剧挥发分的二次反应,降低焦油产率;更多的含氧杂环结构会随着热解温度提高逐渐分解,因而焦油热值逐渐增加。生物炭产率随着温度增加逐渐降低,生物炭pH值和C/N比均逐渐增加,在兼顾生物炭产率和应用于炭基肥制备所需理化性质的同时需充分考虑热解温度影响。     

Soil-profile distribution of primary and secondary plant-available nutrients under conventional and no tillage

Nutrient distributions under no tillage (NT) compared with conventional disk-and-bed tillage (CT) management in the warm, humid region of the southeastern USA need to be assessed so that future placement, quantity, and type of fertilizers can be altered, if necessary, to efficiently match crop demands. We determined soil-profile distributions of pH, N, P, S, K, Ca, Mg, Na, Zn, Fe, Mn, and Cu to a depth of 0.9 m at the end of 8.5 years of continuous CT and NT management on a Weswood silty clay loam (fine, mixed, thermic Fluventic Ustochrept) in southcentral Texas. Most dramatic changes occurred within the 0–0.05 m depth, where soil under NT had lower pH, Fe, and Cu than under CT, but greater P, K, Zn, and Mn. Greater P and K under NT than under CT also occurred below the till-zone (0.15–0.3 m). At a depth of 0–0.3 m, soil under NT contained greater amounts of extractable P, K, Zn, Fe, Mn, and Cu than under CT. Nitrogen fertilization had little effect on nutrient distributions, except resulting in greater extractable K at 0–0.05 m and greater nitrate at 0–0.15 m. Few changes in soil-profile distributions were observed for extractable S, Ca, Mg, and Na. Long-term continuous use of NT on this fine-textured, high-fertility (except for N) soil had no apparent adverse effects on nutrient distributions relative to CT, but enhanced conservation and availability of P, K, Zn, Fe, Mn, and Cu near the soil surface where crop roots proliferate.     

Assessing the effectiveness of conservation measures: Resolving the “wicked” problem of the Steller sea lion

“Wicked” problems are those that are complex and that change when solutions are applied. Many conflicts in conservation fall into this category. The study approached the problem of how to constrain the apparent wickedness of a problem in the conservation management of a species by using simple empirical indicators to carry out iterative assessment of the risk to a population and to document how this risk evolves in relation to the addition of new data and the implementation of management actions. Effects of high levels of uncertainty within data and also concerning population structure were examined through stochastic simulation and by exploration of scenarios. Historical trends in the example used, the Steller sea lion, showed rapid declines in abundance in some regions during the 1980s. The current total population is 130,000-150,000 Steller sea lions through Alaska and British Columbia and this number has been stable since about 1990 in spite of regional differences in population dynamics. Regional differences in the sequence of changes in the number of pups and non-pups, suggested that an internal re-distribution of juveniles could have happened between 1980 and 1990. Current productivity also appears close to the long-term mean. Stochastic population projection using various scenarios showed that, based upon this history, the risk of extinction for the population has declined and is below reasonable thresholds for considering the population to be endangered. The trends in risk suggest that management actions taken since 1990 have probably been effective. Consequently, the conservation management objectives for the Steller sea lion are probably being met. The approach provides a mechanism, based upon experience and scenario analysis, for exploring future policy options and may help to constrain the debate amongst stakeholders about the cost-benefit trade-offs associated with different options.     

Enhanced establishment and growth of giant cardon cactus in an eroded field in the Sonoran Desert using native legume trees as nurse plants aided by plant growth-promoting microorganisms and compost

To evaluate the feasibility of long-term desert reforestation technology of mixed vegetation, cardon cactus (Pachycereus pringlei) seedlings from indoor and outdoor nurseries were planted in the field adjacent to one seedling of potential legume nurse trees: mesquite amargo (Prosopis articulata), yellow palo verde (Parkinsonia microphylla), and blue palo verde (Parkinsonia florida). Some of the planting holes were also supplemented with common dairy compost. Additionally, the combinations of legume tree–cactus were inoculated with either a consortium of desert arbuscular mycorrhizal (AM) fungi, plant growth promoting bacteria (PGPB; the diazotroph Azospirillum brasilense Cd, and the phosphate solubilizer Paenibacillus sp.), or a mixture of all. The field experiments were evaluated periodically during 30 months for survival and growth. Cardons reared in an outdoor screen house survived better in the field than those reared in a controlled growth chamber and hardened later outdoors. Association with any legume nurse tree increased survival and enhanced growth of untreated cardons. For cardons growing alone, application of either compost, AM fungi, and all the treatments combined increased survival. For these plants, no treatment affected plant growth during the first 3 months after transplanting. Later, all treatments, except for AM fungi, enhanced plant growth. However, only 2 years after transplanting the enhanced growth effect of AM fungi was also significant. In the presence of the legume nurse trees, transient positive effects on cardon growth were recorded. General evaluation after 30 months of cultivation showed that the treatments positively affected cardon growth when growing alone or in combination only with mesquite amargo but not with the other two legume trees. This study proposes that young legume trees have the capacity to enhance survival and growth of cardon cactus, depending on the legume cactus combination. Additional treatments such as compost or PGPB can either amplify the effect or else attenuate it.     

Karyotypic and genome size variation in Cajanus cajan (L.) Millsp. (pigeonpea) and some wild relatives

Detailed karyotypes and 4C DNA amounts have been studied in five cultivars of Cajanus cajan and 20 species belonging to Cajanus, Rhynchosia, Dunbaria, Flemingia and Paracalyx. C. cajan shows intraspecific variability and its karyotype is most similar to that of C. cajanifolius (sect. Cajanus) in the morphology and number of satellite chromosomes and the lack of any correlation between chromosome size within the complement and asymmetry. Karyotypes of C. lineatus and C. sericeus belonging to sect. Atylia are similar with respect to maximum r-index and the ratio of longest and shortest chromosomes in their respective complements. C. acutifolius (sect. Frutocosa) is distinct in having a very low ratio (1.44) between the longest and the shortest chromosomes, while in C. albicans, C. goensis, C. scarabaeoides (sect. Cantharospermum) there is no chromosome pair with r-index >2.0. C. mollis and C. volubilis (sect. Volubilis) show similarity with regard to ratio between the longest and the shortest chromosomes and a distinct chromosome pair with an arm ratio of 2.7 and C. platycarpus is distinct (sect. Rhynchosoides) in having the smallest ratio (1.36) between the longest and the shortest chromosomes. 4C DNA amounts in Cajanus and Rhynchosia vary between 3.28 pg to 11.69 pg and 4.92 pg to 11.13 pg respectively, while in Dunbaria, Flemingia and Paracalyx these vary between 4.70 and 7:06 pg. In the genus Cajanus karyotypic features and 4C DNA amounts agree with the sectional classification and bring out a close relationship between C. cajan and C. cajanifolius. This is supported by studies based on seed protein patterns, isozyme analysis, trypsin and chymotrypsin inhibitor patterns, RFLP and RAPD data and crossability relationships. A clear relation between DNA amount and abnormalities effecting the extent of pairing and recombination in interspecific hybrids shows the importance of this study in developing future breeding programme involving C. cajan and its wild relatives that are of potential value.     

Effect of some fungicide seed treatments on the survival of Bradyrhizobium japonicum and on the nodulation and yield of soybean [Glycine max. (L) Merr.]

Several commercial fungicide seed treatments were evaluated for their possible effect on the survival of Bradyrhizobium japonicum on seeds and on the nodulation and yield of soybeans in a greenhouse and a field experiment. quinolate Pro (carbendazim and oxine copper), Vitavax 200FF (carboxin and thiram), and Monceren (pencycuron) had a small effect or no effect on the survival of B. japonicum and on the nodulation and yield of soybeans. They can thus be considered compatible with soybean seed inoculation. Germipro UFB (carbendazim and iprodione), Apron 35J (metalaxyl), and Tachigaren (hymexazol) decreased B. japonicum survival and the nodulation and yield of soybeans and thus cannot be considered compatible with soybean seed inoculation.     

Einfluss der düngungsmethoden auf die entwicklung von zuckerrübenkrankheiten

Während neunjähriger (1994-2002) Untersuchungen in der Versuchsanstalt Ba?cyny (Fahlerde, Fall-Gleyboden, ausgebildet aus leichtem Lehmboden) wurde der Befall mit Krankheiten an der Zuckerrübe in Abhängigkeit von der Düngungsmethode bewertet. Folgende Methoden wurden angewendet: A - Mineraldünger, B - Stalldung und Mineraldünger, C - Stroh-, Gründung und Mineraldünger, D - Kompostdünger und Biopräparate (ökologische Düngung). Auf den Objekten A, B, C wurden bei konstanter Phosphor-Kalium-Düngung die Stickstoffgaben von 0 bis 180 kg.ha^?1 differenziert. Auf dem ökologischen Objekt D ohne Mineraldünger wurden statt Stickstoff die Biopräparate P₅₀₀ und P₅₀₁ verabreicht. Der geringste Befall von Krankheiten wurde an der Zuckerrübe auf jenem Objekt festgestellt, das mit Kompost und den Biopräparaten gedüngt worden war. Im Rahmen der konventionellen Düngungsmethoden wurde allgemein die höchste Intensität der Krankheiten an der mit Stroh, Gründung und Mineraldünger gedüngten Zuckerrübe beobachtet. Ausnahmen von dieser Regel bildete das Vorkommen von echtem Mehltau und Keimlingsfäule. Auf den Objekten A, B, C nahm die Intensität der Krankheiten mit der Steigerung der Stickstoffgabe zu. Auch die auf Objekt D verabreichten Biopräparate stimulierten die Entwicklung der Krankheiten. The effect of various fertilization methods on the diseases of sugar beet was estimated on the basis of nine-year studies (1994-2002) conducted in the Experimental Production Farm in Ba?cyny on loess-based, sedimentary-gley, light-clay soil. The following fertilization methods were applied: A - mineral fertilization, B - mineral and manure fertilization, C - straw, green manure and mineral fertilization, D - ecological compost and biodynamic preparations fertilization. In the objects A, B and C fertilized with phosphorus and potassium, various doses of nitrogen ranging from 0 to 180 kg/ha^?1 were used. In the ecological object D, where mineral fertilization was not used, biodynamic preparations P₅₀₀ and P₅₀₁ were applied instead of nitrogen. The lowest ratio of the diseases of sugar beet was observed in the object fertilized with the compost and biodynamic preparations. In view of the conventional fertilization methods, generally the highest incidence of diseases was noted in the sugar beet fertilized with straw, green manure and mineral fertilizers. The exception was the occurrence of powdery mildew and the black leg. In objects A, B and C the incidence of the diseases increased with the increase in nitrogen doses. The applied biodynamical preparations in the object D stimulated the development of diseases too.     

Prospects for control of Pythium damping-off of lettuce with Trichoderma,Gliocladium and Enterobacter spp.

Summary Damping-off of lettuce (Lactuca sativa) caused by Pythium ultimum was studied in pots containing a non-sterile potting mix in the glasshouse. Fifty P. ultimum sporangia g^-1 compost reduced the plant stand to 15% and shoot dry weight to 18%, but this reduction was totally prevented by applying Trichoderma harzianum at 2×10⁵ viable propagules g^-1 potting mix. Gliocladium virens and Enterobacter cloacae also alleviated the damping-off. E. cloacae did not adversely affect the action of the fungal antagonists. The co-existence of the bacterial and fungal antagonists was revealed on the root surface and inner surface of the testa by scanning electron microscopy, indicating the compatibility of the biocontrol agents.     

细菌、真菌及植物氮营养信号研究进展

氮素吸收代谢是所有生物生命活动的核心部分,因此,各种生物对氮的吸收与同化过程都有精细的调节。这种调节依赖于生物对体内氮素状况信号及体外（生长介质中）氮素信号的感受。过去几十年中,在细菌、真菌中已经对氮素营养信号有了较好的研究,而植物中则相对缓慢,但也有了一定的认识。本文重点比较细菌、真菌及植物中氮信号系统的组成,以期为进一步认识植物中的氮信号接受与转导系统提供启示。     

Aircraft operations near concentrations of birds in Antarctica: The development of practical guidelines

Aircraft operations have the potential to disturb and to impact negatively on bird life. A gradient of increasing behavioural response is evident in birds when exposed to increasing aircraft stimulus. The most major disturbance is likely to lead to impacts on the health, breeding performance and survival of individual birds, and perhaps bird colonies. A process of revision to policies on aircraft operations contained in management plans for a number of specially protected areas in Antarctica by the United Kingdom, accompanied by consultations made within the scientific community through the Scientific Committee on Antarctic Research (SCAR) and with operational interests through the Council of Managers of National Antarctic Programmes (COMNAP) resulted in new guidelines being adopted by the Antarctic Treaty Consultative Parties in June 2004. The principal recommendations of the guidelines are that bird colonies should not be overflown below 2000 ft (∼610 m) above ground level and landings within 1/2 nautical mile (∼930 m) of bird colonies should be avoided wherever possible. These guidelines are less stringent and less specific than those that were recommended by the SCAR specialist group on birds, and represent a compromise to accommodate operational needs. While the adoption of clear and consistent guidelines for the operation of aircraft in Antarctica is welcome in that this provides practical advice that is likely to reduce incidences of close aircraft/bird encounters, there remains insufficient knowledge of the interactions between aircraft and birds in Antarctica, and the consequent impacts on individual birds and on bird populations. It is important, therefore, that the guidelines adopted are considered interim, and should be kept under scrutiny with revisions made as new and improved research results appear.     

Potential of wild species for genetic enhancement of some semi-arid food crops

Discovery and incorporation of genes from wild species provide means to sustain crop improvement, particularly when levels of resistance in the cultigens are low and virulent strains of pests and pathogens overcome the host plant resistance. The extent of utilization and the potential of the wild genepool for genetic enhancement were reviewed in five important food crops viz. sorghum, pearl millet, chickpea, pigeonpea and groundnut grown in the semi-arid tropics. Introgression from compatible wild germplasm in the primary gene pool resulted in transfer of new cytoplasmic male sterility systems in pearl millet and pigeonpea, development of high protein, cleistogamous flower and dwarf pigeonpea lines and foliar disease resistant groundnut cultivars. Utilization of wild species in secondary and tertiary gene pools has been generally limited due to sterility, restricted recombination or cross incompatibility. Nevertheless, these species are extremely important as they contain high levels of resistance to several important biotic and abiotic stresses. Several of them, like those belonging to the Parasorghum section and the rhizomatous Arachis species are sources of multiple resistances and hold great promise to sustain crop productivity.