泥石流排导槽最小不淤纵坡初步试验研究

纵坡是泥石流排导槽设计重要参数之一。通过试验研究,对2组粒径级配,8种不同容重的泥石流在排导槽内运动最小纵坡进行研究,结果表明：（1）粒径小于0.05mm的泥流可以在很小排导坡度下流动;同一容重、级配的泥石流,随排导槽纵坡减小,槽内运动速度逐渐减缓,泥深增大;（2）随泥流容重的增大,排泄其所需纵坡将增加;泥石流量最小不淤纵坡除与容重有关外,还与固体物质粒径大小、细颗粒含量等有密切关系。     

泥石流排导槽冲淤规律观察研究

泥石流排导槽是泥石流治理的一项重要工程措施,昆明以黑水河排导槽为重点,结合省内外有关沟域排导槽工程观测情况展开对排导槽冲淤规律分析研究。采用理论推导结合实际分析、各类型排导槽的应用通守优化分析,建立模型,找出其内在联系及适用范围,为泥石流排导槽的设计及推广应用确定了科学依据。     

容重对土壤水分蓄持能力影响模拟试验研究

通过人工改变土壤颗粒级配,并设置不同容重水平,测定土壤水分特征参数,研究了容重对土壤水分蓄持能力的定量影响。结果表明:(1)容重对土壤水分特征曲线、比水容量有较大影响,试验土壤各吸力段水分蓄持能力均随容重增大递减,比水容量也随容重增大递减。(2)容重对试验土壤饱和含水量、田间持水量、凋萎系数有较大影响,此3个水分参数均随容重增大递减。饱和含水量与容重呈幂函数负相关关系,田间持水量及凋萎系数均与容重呈指数负相关关系。(3)容重对试验土壤有效水、易效水、迟效水含量有较大影响,此3水分参数均随容重增大递减,分别与容重呈指数、幂函数、对数负相关关系。     

容重对土壤水分入渗能力影响模拟试验

通过人工改变土壤颗粒级配,配制典型砂壤、中壤、黏壤,并设置不同容重水平,用土柱积水入渗模拟了土壤容重对其入渗能力的影响,为土壤改良和促进天然降水转化利用提供理论依据。结果表明,容重对土壤入渗能力有较大影响。试验土壤入渗能力随容重增大递减,3种典型土壤稳定入渗速率与容重均呈对数负相关,砂壤120 min累积入渗量与容重呈幂函数负相关,中壤、黏壤则呈线性负相关。考斯加科夫入渗模型中,表征初始入渗速率的参数随容重增大递减,表征入渗能力衰减速度的参数则随容重增大递增,说明土壤初始入渗能力随容重增大递减,入渗能力衰减速度随容重增大递增。     

坡面尺度土壤特性的空间变异性

通过对20m长坡面土壤特性空间变异性的经典统计学分析,结果表明:(1)在同一土壤剖面内,各级粒径含量呈弱变异性,而有机质含量随土层深度的增大而逐渐降低,呈中等变异性;(2)土壤干容重的空间变异性较小,呈弱变异性,但土壤饱和导水率的空间变异性较大,呈中等变异性;(3)水分特征曲线具有一定的空间变异性,比水容量空间变异性较大,呈中等变异性。坡面土壤饱和导水率和干容重的等值线图表明,土壤饱和导水率的变化趋势并不仅仅取决于土壤干容重的相对大小,可能与有机质含量、黏粒含量以及根系分布情况等也有一定的关系。     

泥石流梁式格栅坝拦砂性能试验研究

通过特殊泥石流试验装置 ,对泥石流梁式格栅坝拦砂性能进行研究 ,初步得到 :梁式格栅坝有全部闭塞、临时闭塞、半闭塞、未闭塞 4种闭塞类型。当梁间距 b与泥石流体中最大颗粒粒径 dm ax之比 b/ dmax≤ 1.0时 ,格栅坝基本闭塞 ;b/ dmax≥ 1.5时 ,格栅坝未闭塞 ;1.0 相似文献   

西藏亚东县加热沟泥石流形成条件及防治对策

"9.18"印度锡金邦6.8级地震导致亚东县城附近的加热沟产生大量的松散物源体,加之沟域汇水面积较大、纵坡降大,暴雨触发泥石流的危险性增强,危害性大。加热沟为低频稀性、暴雨沟谷型泥石流,震后易发程度属易发,激发泥石流的临界雨强可能降低,爆发频率可能提高,存在溃决性泥石流灾害链风险。针对物源多、主河携带能力差,堆积区沟道排导限制,提出"拦蓄为主+固床稳坡"的防治对策。     

黄河泥沙充填复垦中土工布排水拦沙效果的模拟试验

为验证土工布用于加速引黄河泥沙充填采煤沉陷地的后期侧向排水及降低排水中泥沙含量的效果,在室内进行了基于土工布的泥沙充填排水模拟试验。该试验在玻璃槽内完成,设计3个试验处理,分别为ZT-250(整个断面开口+铁丝网+ZW-250土工布)、ZT-300(整个断面开口+铁丝网+ZW-300土工布)以及CK(断面中间部分开口+可调节高度的塑料板)。测定了3个处理的排水含沙量及泥沙粒径、玻璃槽内表层泥沙粒径以及充填表层和底层泥沙含水率随时间的变化。结果表明:1)3种处理排水含沙量整体差异较小,但使用土工布处理的排水含沙量随时间的延长逐渐降低,而对照处理排水含沙量随时间的延长逐渐增大;2)排水初期和中期,对照CK的排水中泥沙的黏粒含量均高于使用土工布的2个处理。排水后期CK的黏粒含量介于处理ZT-250和ZT-300之间。随着试验的进行,使用土工布的2个处理排水中泥沙的黏粒含量逐渐升高,粉粒含量逐渐降低,而对照处理呈现相反的变化趋势。使用土工布的2个处理拦沙效果较为稳定。3)3种处理充填表层泥沙粒径级配无明显差异,但使用土工布处理充填的表层泥沙的极细砂粒含量较高。4)3种处理充填泥沙表层和底层含水率变化存在差异,使用土工布可以加速泥沙中过饱和水的排除,其中处理ZT-250排水效果最好。该研究可为中国东部高潜水位平原矿区采煤沉陷地引黄河泥沙充填复垦的快速排水工艺革新提供依据。     

隧道弃渣颗粒粒径对泥石流起动的控制作用——以兰州市烂泥沟为例

泥石流物源中的颗粒级配直接影响泥石流的形成机理和起动模式,是泥石流治理工程设计时需要明确的重要参数。隧道开挖形成的弃渣不同于原沟床的泥石流物质,通过对兰州市烂泥沟隧道弃渣和原沟床泥石流物质的颗粒级配、孔隙度、透水性能的差异对比,探讨了隧道弃渣颗粒级配对泥石流起动的影响。研究表明,隧道弃渣松散无黏结,粒径变化范围主要在0.075~60 mm之间,其中>2 mm的砾石级颗粒占总渣量的80.49%~85.07%,平均粒径为8.27 mm,以砾石级为主,黏粒物质几乎没有。隧道弃渣颗粒渗透系数是原沟床泥石流物质的36倍,具有极高渗透性,遭遇一般降水难以起动弃渣堆形成泥石流。结合研究区地质环境特点,构建了隧道弃渣诱发或加剧泥石流的起动模式,据此提出了隧道弃渣诱发或加剧泥石流的治理需按3个阶段进行。     

浙江省青田县某移民点泥石流灾害防治方案探讨

从浙江省青田县某移民点泥石流发生的基本条件出发,对该区泥石流的活动特征进行了分析,详细讨论了防治措施、工程布置的依据以及格栅坝、排导槽等工程措施的结构设计,为该区泥石流的综合治理提出了科学的建议.     

低氮和干旱胁迫对富士和秦冠生长及氮素利用的影响

【目的】以富士（Fuji）、 秦冠（Qinguan）嫁接在平邑甜茶（Malus hupehensis Rehd.）上的当年生盆栽苗为试验材料,采用砂培方法,研究了缺氮胁迫和干旱对富士和秦冠生长情况、 光合参数、 植株各部位氮磷钾含量及氮素利用效率的影响,分析比较了低氮干旱条件下富士和秦冠生长及氮素利用的差异,以期为果树生产高效肥水利用提供理论指导。【方法】试验共设四个处理: 正常氮正常水（ZZ）、 低氮正常水（DZ）、 正常氮干旱（ZG）、 低氮干旱（DG）。氮素和水分均设置两个水平,分别为正常氮（6 mmol/L NO-3-N）、 低氮（0.3 mmol/LNO-3-N）、 正常供水（保持盆中砂子相对含水量为饱和含水量的80%~85%）、 干旱处理（保持盆中砂子相对含水量为饱和含水量的60%~65%）。【结果】富士和秦冠的生物量（茎和叶）、 株高茎粗等生长指标以及光合速率、 气孔导度、 蒸腾速率均为正常氮正常水（ZZ）＞低氮正常水（DZ）＞正常氮干旱（ZG）＞低氮干旱（DG）,并且相对应处理下秦冠的以上指标均高于富士;正常供水下,缺氮处理使富士、 秦冠的根冠比比正常氮处理均有所增加,富士提高了2.05%,秦冠提高了22.40%。富士和秦冠的氮、 磷、 钾含量均表现出正常氮正常水（ZZ）＞低氮正常水（DZ）＞正常氮干旱（ZG）＞低氮干旱（DG）; 氮、 钾元素含量在植株各部位的分布顺序依次是叶＞根＞茎,磷元素则是根＞叶＞茎;光合氮素利用效率（PNUE）和氮素利用效率表现为秦冠处理之间差异极显著,富士处理之间差异不显著;秦冠的PNUE和NUE明显高于富士,在低氮正常水（DZ）处理下,秦冠氮肥利用率比富士高42.07%,在低氮干旱（DG）处理下高64.14%;低氮胁迫下富士和秦冠的NUE显著提高,并且秦冠提高的幅度高于富士。【结论】施用氮肥能够显著提高富士与秦冠的干物质量,同等水肥条件下,秦冠生长优于富士;水分亏缺会减少叶片对氮的吸收,干旱条件下适度增施氮肥,可提高果树的抗旱能力;低氮干旱胁迫下秦冠的生长指标、 光合指标及氮素利用效率指标均优于富士,表现出较强的抗低氮干旱胁迫的能力。     

Pasture Vegetation Elemental Analysis by Laser-Induced Breakdown Spectroscopy

Laser-induced breakdown spectroscopy (LIBS) is a new technique for the analysis of plant material. This study investigates the application of LIBS to pasture-based plant samples. The LIBS measurements were obtained from pelletized pasture samples (100 samples) that had been also analyzed by inductively coupled plasma–optical emission spectroscopy (ICP-OES) following microwave digestion for calibration and comparison purposes. Comparisons for elements sodium (Na), potassium (K), magnesium (Mg), calcium (Ca), manganese (Mn), iron (Fe), copper (Cu), zinc (Zn), boron (B), phosphorus (P), and sulfur (S) showed that LIBS could be used for almost all the standard profile total elements with concentrations down to low mg/kg levels (observed error of Na: 0.024 percent, K: 0.18 percent, Mg: 0.016 percent, Ca: 0.073 percent, P: 0.017 percent, Mn: 31 mg/kg, Fe: 150 mg/kg, Zn: 6.6 mg/kg, and B: 1.1 mg/kg). Elemental analysis at less than mg/kg levels was not possible using LIBS. The elements S and Cu were particularly difficult to analyze with reliability using LIBS at the concentration levels found in the plant samples. Replacing microwave digestion and subsequent ICP analysis with a direct analysis of dried plant samples using LIBS has the potential to improve the productivity and reduce the cost of testing.     

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 from individuals who have expertise and a record of accomplishment in research areas related to ecology,agro-hydrology,     

Biodiversity and ecogeography of wild Lactuca spp. in some European countries

Staff members of the Department of Botany of Palacký University in Olomouc and Gene Bank Department – Workplace Olomouc, Research Institute of Crop Production in Prague, Czech Republic, conducted an expedition in seven European countries (Austria, Czech Republic, France, Germany, Italy, the Netherlands, Switzerland) in August/September 1999 to collect wild Lactuca spp. germplasm and study its geographic distribution, ecology and biodiversity. During the mission, more than 600 locations were visited resulting in the collection of 602 seed samples (accessions) of wild Lactuca species and 13 seed samples of related genera (Chondrilla and Mycelis). Lactuca serriola f. serriola, L. serriola f. integrifolia, L. saligna and L. viminea subsp. chondrilliflora were prevalent in southern Europe (Italy, France), however, only L. serriola was common in central and western Europe (Austria, Czech Republic, Germany, Netherlands, Switzerland). The greatest diversity of Lactuca species was found in France, where also the most seed samples (165) were collected. The most characteristic habitats with a high density of Lactuca spp. populations were observed along roads and highways, grassy ditches, ruderal communities, and dust-heaps. Natural infections by powdery mildew (Erysiphe cichoracearum) and downy mildew (Bremia lactucae) on some wild Lactuca spp. were observed. Recent observations concerning the geographic distribution, population structure, habitats, and natural occurrence of diseases of Lactuca spp. are discussed. This assemblage of genetic resources of Lactuca spp. can serve as the basis of future studies of species diversification, spatial population structure, plant microevolution, domestication processes, and genetic variability of host-parasite interactions.     

Macroinvertebrates in North American tallgrass prairie soils: effects of fire, mowing, and fertilization on density and biomass

The responses of tallgrass prairie plant communities and ecosystem processes to fire and grazing are well characterized. However, responses of invertebrate consumer groups, and particularly soil-dwelling organisms, to these disturbances are not well known. At Konza Prairie Biological Station, we sampled soil macroinvertebrates in 1994 and 1999 as part of a long-term experiment designed to examine the effects and interactions of annual fire, mowing, and fertilization (N and P) on prairie soil communities and processes. For nearly all taxa, in both years, responses were characterized by significant treatment interactions, but some general patterns were evident. Introduced European earthworms (Aporrectodea spp. and Octolasion spp.) were most abundant in plots where fire was excluded, and the proportion of the total earthworm community consisting of introduced earthworms was greater in unburned, unmowed, and fertilized plots. Nymphs of two Cicada genera were collected (Cicadetta spp. and Tibicen spp.). Cicadetta nymphs were more abundant in burned plots, but mowing reduced their abundance. Tibicen nymphs were collected almost exclusively from unburned plots. Treatment effects on herbivorous beetle larvae (Scarabaeidae, Elateridae, and Curculionidae) were variable, but nutrient additions (N or P) usually resulted in greater densities, whereas mowing usually resulted in lower densities. Our results suggest that departures from historical disturbance regimes (i.e. frequent fire and grazing) may render soils more susceptible to increased numbers of European earthworms, and that interactions between fire, aboveground biomass removal, and vegetation responses affect the structure and composition of invertebrate communities in tallgrass prairie soils.     

Properties of anaerobically digested and composted municipal solid waste assessed by linking soil mesofauna dynamics and nitrogen modelling

We have studied the effect of anaerobically digested (ADMSW) and composted municipal solid waste (CMSW) on mineralization and foodweb dynamics to verify the hypothesis that ADMSW would immobilize N right after addition to soil in contrast to addition with CMSW. Another hypothesis was that the mesofauna (enchytraeids and microarthropods) would stimulate N release from the decomposer community. We measured excretion of -N and urea-N from the mesofauna and hypothesized that enchytraeids would release urea. ADMSW and CMSW were amended to pots with sandy loam and barley. The pots were divided into treatments with or without mesofauna. Mesofauna, plant N and biomass, soil N and ergosterol (fungal biomass) were measured over a 113-day period of four equidistant samplings. Soil respiration, N mineralization and N release by the mesofauna were modelled from concurrent studies. ADMSW- and CMSW-treated soils initially (<20 days) immobilized N. The amendments did not increase plant growth substantially, and this was probably due to N-limitation in the early stages of plant growth. Enchytraeid abundance was about three times higher in ADMSW- than CMSW-treated soils, indicating that ADMSW contained more labile compounds, bacteria, and microfauna. The mesofauna did not affect N-content, but the cumulated -N excreted by the mesofauna was estimated to be substantial and about one-fifth of total plant N in ADMSW. An explanation for this discrepancy might be that in the absence of the mesofauna, other members of the detrivore and microbivore community performed the mesofauna’s function. Neither enchytraeids nor microarthropods excreted urea.     

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 from individuals who have expertise and a record of accomplishment in research areas related to ecology,agro-hydrology,     

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 from individuals who have expertise and a record of accomplishment in research areas related to ecology,agro-hydrology,     

Variation in quality parameters between and within 14 Nordic tree fruit and berry species

Abstract

A 3-year study was carried out to investigate quality parameters in 14 tree fruit and berry species grown in southern Norway. The species were blueberry, apple, aronia, sour cherry, sweet cherry, red raspberry, strawberry, blackcurrant, gooseberry, red currant and elderberry, harvested along with wild bilberry, cloudberry and lingonberry. Significant differences between species were identified for all quality parameters. The coefficient of variation between species was lowest for pH (12.5%), dry matter (18.9%) and soluble solids (25.3%), followed by titratable acids (59.3%), total phenolics (83.8%), antioxidant capacity FRAP (85.7%) and antiradical power by the DPPH-assay (97.8%), total monomeric anthocyanins (132%) and ascorbic acid (137%). Average coefficient of variation within species were lower and ranged from 4 (pH) to 62% (ascorbic acid). Only the FRAP values were significantly affected by harvesting year with lower levels in 2004 than in 2005 and 2006. There were significant interactions between species and harvesting year for dry matter, soluble solids, pH, ascorbic acid and FRAP. The results indicate generic ranges in composition within species independent upon growing location and climate, and the composition of the tree fruits and berries is not likely to deviate from these ranges. It is concluded that desirable composition of tree fruits and berries and their products should primarily be achieved by selection among species rather than searching fors broadened variation within individual species.     

Potassium Fixation and Release Characteristics in Rhizosphere and Nonrhizosphere Soils for a Rapeseed–Rice Cropping Sequence

Potassium (K) fixation and release in soil are important factors in the long-term sustainability of a cropping system. Changes in K concentration and characteristics of K fixation and release in rhizosphere and nonrhizosphere soils in the rapeseed (Brassica napus L.)–rice (Oryza sativa L.) rotation were investigated using a rhizobox system. The concentrations of different forms of K in both rhizosphere and nonrhizosphere soils decreased with plants compared to without plants, regardless of K fertilizer application. Potassium uptake by crops mainly came from the rhizosphere soil. In the treatment without K fertilizer (–K), the main form of K supplied by the soil to the crops was 1.0 mol L^?1 nitric acid (HNO₃) nonextractable K, followed by nonexchangeable K, and then exchangeable K. In the treatment with K fertilizer (+K), the main K forms supplied by the soil to the crops were exchangeable K and nonexchangeable K. The amount and rate of K fixation after one cycle of the rapeseed–rice rotation was greater in rhizosphere soil than in nonrhizosphere soil. The amount and rate of K fixation of soil in the +K treatment were significantly less than in the –K treatment. The cumulative amounts of K released with 1.0 mol L^?1 ammonium acetate (NH₄OAc) and 1.0 mol L^?1 HNO₃ extraction increased with the increasing numbers of extractions, but the K-releasing power of soil by successive extraction decreased gradually and finally became almost constant. The release of K was less in rhizosphere soil than in nonrhizosphere soil. The release of K in the +K treatment was similar to that in the –K treatment in rhizosphere soil, but the K release in nonrhizosphere soil was greater with the +K than the –K treatment. Overall, the information obtained in this study will be helpful in formulating more precise K fertilizer recommendations for certain soils.