基于暴雨洪水管理模型的铁路车站片区雨洪模拟及低影响开发效果评价

[目的]减轻西北地区高速铁路车站片区建设过程引起的水资源矛盾问题,实现铁路车站片区雨水的积存、渗透和净化,促进雨水资源的利用和生态环境保护,实现高速铁路绿色施工。[方法]以甘肃省兰州市西客站为研究对象,采用暴雨洪水管理模型(SWMM)研究了传统开发下的雨水径流效应,并对采用生物滞留池、透水铺装、绿色屋顶及生物滞留池+透水铺装+绿色屋顶组合措施方案3种低影响开发(LID)方案进行了模拟。[结果]不同LID措施均能有效削减径流总量、洪峰流量、溢水量及延后峰现时间,其中组合LID方案的控制效果最佳,对洪峰流量和径流总量削减率高达75.9%和41.6%;透水铺装和生物滞留池对洪峰流量和径流总量的削减效果较显著;绿色屋顶单独铺设时,雨洪控制效果较差。[结论]合理采用LID措施可以有效地实现雨水的可持续管理,减小铁路车站片区的洪涝灾害。     

沼气池搅拌的CFD模拟及温度场验证

为了对底侧入式搅拌的沼气发酵池内的流场进行研究,该文采用计算流体力学方法,以上海市崇明县某示范工程的主体沼气发酵池（69.3 m3）为对象,对流场和温场进行计算模拟,并通过温度测量来验证温度数值模拟的可靠性,从而间接验证流场数据准确性。通过温度场的模拟和实测数据对比,整体温场模拟和实测数据在0.05水平下无显著差异;通过流场模拟和工程运行的观察,都反映此发酵池中设计的底侧入式搅拌不能充分实现发酵池的搅拌。但模型在相关设定上仍有与实际不符之处,模型仍有待完善。     

生物炭对日光大棚土壤团聚体结构的影响

[目的]探明果木生物炭对杨凌地区日光大棚土壤团聚体结构的影响,提出适宜该地区的生物炭添加量,为改良日光温室大棚土壤结构,提升作物产量提供科学依据。[方法]设置10,30,50,70,90 t/hm~2共5个生物炭添加量处理,以未添加生物炭处理为对照,采用干筛法和湿筛法,对比分析不同处理的团聚体几何平均直径、平均重量直径、破坏率和分形维数等指标。最后通过分析不同生物炭添加量下的作物产量,综合考虑土壤团聚体指标,提出最优的生物炭添加量。[结果]添加生物炭后,土壤机械稳定性大团聚体含量增加0.6～4.6 mg/kg,机械稳定性微团聚体含量降低4.0%～32.6%;添加生物炭后,粒径为3～2 mm,2～1 mm,1～0.5 mm水稳性大团聚体含量分别增加25.3%～41.2%,22.7%～74.2%,9.1%～46.4%,粒径为0.5～0.25 mm水稳性大团聚体含量降低2.1%～18.1%。生物炭能够促进小粒径微团聚体的形成,但对微团聚体稳定性和总含量没有显著影响。添加生物炭后菠菜鲜重显著提升(68.7%～214.9%)。[结论]生物炭能够改良土壤团聚体结构。综合考虑团聚体、作物产量因素,在日光大棚添加70 t/hm~2生物炭效果最好。     

猪和奶牛粪便的粒径及养分分布对固液分离效率的影响

以猪、奶牛粪便为材料,按＜0.15、0.15-0.5、0.5-1.0、＞1.0 mm不同粒径,分析了猪、奶牛粪便粒径分布,同时分析了4种不同粒径颗粒中N、P、K养分含量,采用XY型螺旋式畜禽粪便固液分离机,在0.5、1.0 mm两种孔径筛网下,进行了固液分离,分析比较了机械固液分离对相应粒径粪便固形物及养分回收效率。结果表明,猪、奶牛粪便粒径分布以〈0.15 mm小颗粒为主,占其粪便重量的57.99%-68.34%,奶牛粪便颗粒粒径大于猪粪便,仔猪与育成牛粪便粒径小于育肥猪与泌乳牛粪便。猪、奶牛粪便中N、P、K养分近80％以上呈水溶性或存在于〈0.15 mm小颗粒之中。粪便机械固液分离获得的固形物与固形物中N、P养分回收比例高于相应筛网孔径粪便颗粒与养分所占比例,奶牛粪便固形物回收率为45.5％,远高于猪粪的27.8％,N、P养分回收率分别为7.14%-19.71%、7.38%-21.18％。     

砾石对石灰土表面干缩裂隙发育特征的影响

[目的]研究砾石粒径及含量对石灰土表面干缩裂隙发育特征的影响,为探索喀斯特地区的水土流失机理提供参考依据。[方法]通过室内模拟试验和数字图像处理技术,研究了砾石粒径(2.0～5.0 mm和5.0～12.5 mm)和砾石含量(0%,10%,20%,30%,40%)条件下的石灰土表面干缩裂隙特征。[结果]①无砾石石灰土平均表面裂隙率仅为3.03%,含砾石石灰土具有更大的表面裂隙率,在大粒径(5.0～12.5 mm)高含量(40%)条件下,表面裂隙率最大,达到8.66%;②当砾石含量增加时,裂隙的形态变得细小且密集,小粒径砾石会使裂隙网络更复杂;③大粒径(5.0～12.5 mm)条件下的土壤表面裂隙率与砾石含量成正线性相关,而小粒径(2.0～5.0 mm)条件下的裂隙率与砾石含量成负线性相关;④砾石会成为裂隙发育的基点,每个砾石颗粒周围都有可能产生围绕砾石或是向外延伸的裂隙。且在砾石形态的棱角处,容易产生向外延伸的裂隙。[结论]石灰土中存在砾石会导致表面裂隙率提高,弱化土体的抗侵蚀能力,是石漠化治理不容忽视的问题。     

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。     

新型锤片式饲料粉碎机分离流道内物料运动规律

基于锤片式饲料粉碎机工作状况,研究物料颗粒在气固两相流中运动轨迹的数学模型,得到物料颗粒沿坐标轴方向上的运动微分方程和位移方程;并使用 MATLAB 对该数学模型进行了数值模拟,得到了物料颗粒理论运动轨迹,对模拟结果按入口固相颗粒速度大于、等于、小于气相速度3种情况进行研究;使用高速摄像机对分离流道内部分颗粒进行跟踪拍摄,并取粒径2 mm目标颗粒和粒径8 mm完整颗粒,对2种物料颗粒理论模型运动轨迹与真实运动轨迹进行了比较,验证了数学模型的合理性.对进一步研究宏观物料运动、颗粒分布及分离装置结构等提供了参考.     

沙粒粒径与含沙量对离心泵空化特性的影响

为了研究沙粒粒径与含沙量对离心泵空化特性的影响,对含沙条件下与清水介质下离心泵内部空化流场进行数值计算.所采用沙粒粒径分别为0.005、0.010、0.015 mm,含沙量分别为0.5%、1.0%、1.5%.通过对清水介质外特性与平头圆柱空化流动进行数值计算并与试验结果相对比,验证算法的可靠性.计算结果表明:含沙量为1.0%时,随粒径逐渐增大,沙粒对空化的影响表现为先促进、后抑制;沙粒粒径为0.010 mm时,随含沙量不断增多,沙粒对空化的影响表现为先促进、后抑制.高压条件下,清水介质中无空化泡产生,含沙水流中均有少量空化泡产生.空化充分发展时,与清水介质相比,含沙水中空化泡分布表现为先增大、后接近、再变小.在沙粒磨蚀与空蚀的共同作用下,含沙水流条件下的扬程均低于清水介质下的扬程,且分别随粒径、含沙量的增加,逐渐减小.     

三种泥沙扩散系数模型对双吸离心泵内固液两相流流场计算的影响

作为模拟双吸离心泵内固液两相流的一种常用方法,欧拉-欧拉法中的泥沙扩散系数常通过多种模型进行计算。为选择适宜的泥沙扩散系数模型进而提高固液两相流数值计算的精度,该研究采用3种常见泥沙扩散系数模型Non-diffusion coefficient model（NON-DC）;Diffusion-in-volume of fluid model（Diffusion-in-VOF）;Diffusion coefficient affected by particle diameter and particle concentration model （DC-PDPC）,在25、100和200 μm 3种含沙粒径和不同流量(0.6和1.0倍额定流量)条件下,对双吸离心泵内固液两相流场进行数值模拟,分析其对泵内固相浓度和固相速度的定常和非定常结果的影响。结果表明：1）当颗粒粒径不大于100 μm时,3种模型计算得到的双吸离心泵内固液两相流的固相浓度和速度定常结果基本相同;当颗粒粒径大于100 μm时,定常结果有所差异,随着颗粒粒径的增大,差异逐渐增大,差别最大可达60%。2）在不同颗粒粒径的条件下,采用3种模型得到的固液两相流场的固相浓度和速度非定常结果差异较大,且随着颗粒粒径的增大,差异逐渐增大,差别最大可达30%。含沙颗粒粒径不大于100 μm时,3种模型得到的定常结果基本相同;而大于100 μm时,定常结果差异较大;同样地,在不同含沙粒径条件下的非定常计算结果也差异较大,需要选择合适的泥沙扩散系数模型。3）定常计算时,当颗粒粒径不大于100 μm时,推荐NON-DC模型;随着颗粒粒径的增大,推荐使用DC-PDPC模型;当非定常计算时,推荐使用DC-PDPC模型。研究为准确地进行离心泵内固液两相流数值计算提供参考。     

聚光集热苦咸水蒸馏装置中含吸光颗粒水体的光吸收特性

传统太阳能蒸馏装置存在传热热阻大,传热换热环节多等缺陷,导致太阳能蒸馏装置热能利用效率低和淡水产量小,鉴于此,该文设计一种新型基于聚光集热的苦咸水蒸馏装置,利用抛物碟式聚光器将入射太阳光汇聚并直接在含有大量黑色多孔颗粒苦咸水体内完成光热转化,克服了传统太阳能蒸馏器光传输方向与热传输方向相反的缺点,减少了装置传热换热环节,使得聚光直接加热苦咸水蒸馏产水得以实现,该文对于装置中实现光热直接转化的水体光吸收特性展开试验测试和理论分析,借助光学积分箱对影响水体模拟受热温升阶段和沸腾蒸发阶段光吸收特性的吸光颗粒粒径、颗粒丰度及光程等因素展开研究。结果表明,含较小粒径吸光颗粒的水体光吸收特性较好,在模拟受热温升过程中,含粒径为0.5 mm颗粒的水体最大光吸收比比含有粒径为1.0 mm颗粒的水体增加9.0%,模拟受热沸腾过程中,丰度为6.7 g/L水体光吸收比是丰度为0.75 g/L水体的4.94倍,且水体光吸收比随沸腾程度呈指数函数变化规律。该研究结果为太阳能苦咸水蒸馏技术的热能高效利用提供参考。     

“绿色革命”以来大气CO2浓度升高对C3作物营养品质的影响

自20世纪60年代"绿色革命"以来,育种技术和农耕技术的发展促进了农作物产量的大幅提升,然而作物的营养品质出现下降趋势。在相似的遗传背景下,大气CO_2浓度升高会使单位体积农作物产品的营养元素含量下降,因此"绿色革命"至今,农作物产品的营养元素下降可能受大气CO_2浓度升高影响。通过植物生长箱模拟"绿色革命"初期和目前的大气CO_2浓度水平(310μmol/mol和400μmol/mol),针对主要C_3作物水稻、小麦和大豆,研究"绿色革命"以来大气CO_2浓度升高对其籽粒的C、N、Fe、Zn元素含量的影响,结果表明:CO_2浓度升高对3种作物籽粒的C元素含量几乎没有影响,变化幅度在±1.5%之间;籽粒的N、Fe、Zn元素含量普遍呈现下降趋势,但均未达到显著水平。     

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.     

Faculty positions:Center for Agricultural Resources Research,Chinese Academy of Sciences

正The Center for Agricultural Resources Research(CARR),the Institute of Genetics and Developmental Biology(IGDB),Chinese Academy of Sciences,invites applicants for several research group leader positions.CARR is one of the research organizations in Chinese Academy of Sciences(CAS).We seek nominations and applications     

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.     

Collection and preliminary evaluation of native turfgrass accessions in Italy

Despite a raising interest on turfs in Italy, all theavailable varieties of this kind in the Country are of foreign origin, and areoften poorly adapted to the prevailing climatic conditions. This prompted tobegin a collection activity of indigenous turfgrass species, with the ultimategoal of identifying promising materials for future breeding based on localgenetic resources. The collection was carried out in three areas of Italy, viz.the northern Po Plain, the coastal region of Liguria, and the island of Sardiniathat are characterised, respectively, by subcontinental, warm temperate, andtypical Mediterranean climate. Altogether, 141 sites were visited, yielding 226accessions belonging to eight species of potential interest for turfs:Poa pratensis, Poa trivialis,Festuca rubra, Festuca arundinacea,Lolium perenne, Agrostis stolonifera,Agrostis tenuis, and Cynodon dactylon,this last being a warm-season grass. Poa pratensis andCynodon dactylon were mostly collected in northern Italyand Sardinia, respectively, whereas Festuca arundinacea andLolium perenne were rather ubiquitous. The collection sitesranged from 0 to 1040 m asl, but sites over 750 m wereonly visited in the inner part of Sardinia. All the accessions, collected aswhole plants, were transplanted at Lodi, northern Italy, where they are beingevaluated. Their preliminary evaluation for traits of importance for turf use,such as sward colour and overall quality, highlighted the great variation andthe occurrence of interesting accessions in all species. Other characters wererecorded, bearing specific importance in individual species, and in all casespromising accessions were identified. The germplasm of Festucarubra, Festuca arundinacea, and Loliumperenne proved highly infected by endophytic (symbiotic) fungi of thegenus Neotyphodium.     

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.     

Leaf position and genotype differences for mineral element concentrations in sorghum grown on tropical acid soil 1

Mineral element deficiencies and toxicities are common problems associated with sorghum [Sorghum bicolor (L.) Moench] production on acid soils. To better understand some of the mineral element problems and the analysis of plant tissue of sorghum plants grown on acid soils, four sorghum genotypes were grown on an acid Oxisol at Carimagua, Colombia limed with dolomite at 2 and 6 Mg ha^‐1.

Samples for mineral element analyses were obtained from leaves at different positions on the four genotypes. Concentrations of P and Mg were highest in the flag leaf (Leaf No. 1) and decreased as the position on the plant declined from the top of the plant for plants grown at 2 Mg lime ha^‐1. Similar decreases in P, Mg, K, and Zn concentrations occurred in plants grown with 6 Mg lime ha^‐1. Concentrations of Ca, S, Si, Mn, Fe, Cu, and Al increased as leaf position declined from the flag leaf for plants grown at 2 and 6 Mg lime ha^‐1. The higher lime supply enhanced Ca and reduced Mn and Fe concentrations in leaves. Differences in mineral element concentrations for the four genotypes used were fairly extensive. The elements to show the greatest range among genotypes were Al and Si and the elements to show the least range among genotypes were P, K, and S. Care should be used in collecting leaf samples for plant analysis and genotypic differences for accumulation of mineral elements should be considered in interpretation of results.