塔里木河下游土壤特性及荒漠化程度研究

通过对塔河下游土壤理化性质的分析,结果表明塔河下游土壤除全磷外,有机质等指标存在垂直分布差异,出现显著差异的土层深度为50 cm。在0~15 cm范围,距离河道不同距离处土壤含水量无显著差异,自15cm深度开始,距河道50m处土壤各土层含水量与距河道距离为300,500 m处含水量有显著差异,而距河道距离为300 m与500 m处土壤含水量之间则无显著差异。在0~50 cm土层,塔河下游土壤全氮(y)与有机质(x)之间的最佳模型为线性模型,方程为y=0.0278 0.05x(R2=0.9524),在50~170 cm土层,二者之间关系为:y=0.0659e0.3126x(R2=0.904)。依据土壤质量不同,塔河下游基本可分为上段和下段,上段土壤养分含量相对较高。塔河下游地区上层土壤(0~50 cm)50年来养分损失严重,有机质含量下降显著,土壤pH值升高,土壤荒漠化程度严重。     

基于分形维数的中小河流滩地沉积物空间分布研究

以浙江省龙游县灵山港滩地沉积物为研究对象,在现场监测和室内测定的基础上,运用分形方法,分析了山丘区中小河流滩地沉积物空间分布格局及其影响因素。结果表明:滩地沉积物在空间分布上具有明显的分段、分区、分层特征。土壤分形维数从上游至下游呈增大趋势;在河道横断面上,离水0～16 m为土壤分形维数的高变幅区,离水16～49 m为低变幅区,离水49 m到滩地边界为平稳区;垂向上,0—20 cm层土壤分形维数小于20—40 cm层。砾石分形维数从上游至下游逐渐增大;在河道横断面上,砾石主要分布在离水边缘4～33.5 m范围内,在该范围内,砾石分形维数随离水距离增大而增大。沉积物空间分布差异性主要受水流、植被、采砂、滩地地形和周期性洪水等因素的影响。对于采砂严重的滩地,修复中需要考虑沉积物分布的分段、分区、分层特点,配置组成适宜的基质,保证滩地的稳定和功能的有效发挥。     

石羊河尾闾-青土湖水面形成对土壤分形维数和植被的影响

以石羊河尾闾青土湖水面形成区的土壤及植被为研究对象,利用植被及土壤调查取样方法,调查分析了水平距水面0～450 m,垂直0—60 cm土层的土壤粒径及植物多样性。利用分形几何学方法对土壤颗粒的分形特征进行分析,以探讨土壤颗粒分形维数与植被特征间的关系。研究结果表明:不同土层及不同水面距离的土壤分形维数在2.10～2.92,平均值为2.55;呈现随距水面距离增大而波动变小的趋势,0—20 cm土层在0~150 m土壤粒径分形维数呈缓慢增加趋势,在150 m处达到最大,随后逐渐降低;而20—40 cm,40—60 cm土层在0~100 m呈缓慢增加趋势,在100 m处达到最大;植物物种多样性变化与土壤分维数的变化具有较好的对应关系;各多样性指数随水面距离变化趋势一致,在距水面0~50 m和400~450 m处多样性达到最大。草本的重要值在距水面200 m处达到最大,灌木的重要值在距水面300 m处达到最大值,草本植物对区域植物多样性影响较大,但灌木植物重要值与土壤特征的变化关系更密切;线性回归分析表明在0—20 cm,40—60 cm土层,分形维数与多样性、均匀度和优势度指数呈显著负相关,在干旱沙漠地区,土壤颗粒分形维数也可作为一个反映评价土壤演变程度的综合定量指标。     

铁路交通对铁路旁土壤重金属污染的影响——以陇海铁路郑州—圃田段为例

以陇海铁路郑州-圃田段为例,在野外调查、采样和实验室分析的基础上,探讨了铁路交通对周围土壤N i、Pb、Cr、Zn、Cu和Cd六种重金属含量与分布的影响。结果表明,铁路南侧农田土壤六种重金属元素都出现不同程度的富集,最大含量均分布在距铁路路基30m的范围内,随着距离的增加,各重金属元素含量表现出不同的下降趋势。土壤各重金属污染程度的次序为:Zn>Pb>Cd>Cu>Cr>N i。土壤Pb和Zn污染最为严重,近路基处为重度污染,随着距路基距离的增加,由中度污染逐渐变为轻度污染。土壤N i和Cr虽不构成污染,但仍具有明显的铁路影响特征。在距路基10 m范围内为土壤重金属重度污染带,10~100 m范围内为中度污染带,100~500 m范围内为轻度污染带。     

铅锌矿区周边农田土壤跳虫群落特征与重金属污染的关联

以云南兰坪铅锌矿区周边的农田为对象,按距矿区距离设四条样带,每个样带按距河流由近至远等距选3个样点进行定量采样,测定和分析土壤跳虫物种多样性和群落结构、土壤重金属含量和理化性质、及跳虫体内的铅含量.共获跳虫26种,平均密度12042 ind·m2.样点与矿区或河流距离增加,土壤中镉、铅和锌含量下降,跳虫体内重金属含量下...     

应用物元分析法评价矿区周边土壤重金属污染的变化

为分析煤矿开采对土壤重金属污染水平的影响,尝试利用物元分析和主成分分析(PCA)方法对宿州市矿区周边土壤重金属污染水平进行评价。结果表明:(1)煤矿开采、堆放对土壤重金属污染具有重要影响,与非矿区背景值相比,Cr含量达到非矿区土壤背景值的2~4.17倍,Cd含量达到非矿区土壤背景值的1~3.05倍,Pb和Cu含量达到非矿区土壤背景值的2倍左右,As的含量略高于非矿区土壤背景值。(2)综合关联度结果显示,土壤重金属污染在100 m处未达到轻度污染的标准要求,但具备向轻度污染转化的条件;200 m和400 m处分别达到轻度污染和清洁等级要求,但隶属该等级的程度不强,且随着距离增大土壤重金属含量和污染程度均在下降。(3)物元模型能够揭示每个土壤重金属元素的分异信息和综合评价的中间信息,适用于土壤重金属污染水平评价。     

明沟排水对盐渍化枣田土壤盐分的影响

[目的]研究明沟排水对盐渍化枣田土壤盐分分布规律的影响,明确明沟排水降盐效应,为提高枣树经济效益和生态防护效应以及盐渍土长期改良治理措施研究提供理论依据。[方法]通过对盐渍化枣田土壤进行调查取样,并对该土样进行水溶性盐含量、电导率、pH值和土壤盐基离子当量比的测定。[结果]同一深度土层,随着与明沟距离的增加,盐基离子含量呈现先降低后增加趋势。距离明沟0m处盐基离子含量最高,之后随距离的增加含量显著降低,在40m处达到最低,40m以后盐基离子含量显著增加。此外,距离明沟40m处土壤盐害作用明显降低,盐基离子类型由NaCl型转变为盐害较轻的CaCl_2型和Na_2SO_4型。[结论]明沟排水降盐效果最佳的范围在40m左右;由于滴灌和离子迁移速率等因素的影响,在土壤表层和底层出现了盐基离子聚集现象。     

亚热带典型人工林土壤酸化特征及其生物学机理初步分析

对亚热带典型人工林土壤pH和酸化生物学机理的研究表明:荒草地种植马尾松和木荷20年以后土壤的pH发生了变化,在0 ～ 60 cm处降低了0.12～0.47个单位;垂直方向上在距离树干10 cm处马尾松0～20cm土层pH低于木荷,20～60 cm土层pH大于木荷;水平方向上随着与树干距离的增加土壤pH受树木影响的程度逐渐降低,距离树干20 cm处土壤pH受树木的影响最大.树干茎流雨可能是树干基部附近土壤加速酸化的重要因素,根系的分布及其对盐基阳离子的吸收是造成马尾松和木荷土壤剖面出现酸化差异的主导因素.     

土壤重金属迁移模拟研究的现状与展望

随着工业发展和废弃物的排放不断增加,土壤重金属污染已经成为一个世界性环境问题。土壤重金属的分布转化以及污染修复的研究受到广泛关注,数学模型及计算机模拟研究成为重要的研究手段。该文对土壤重金属迁移的模拟研究的进展进行了回顾与归纳,集中阐述了对流弥散和经验随机两大类模型的特点和应用,并指出了研究中存在的问题及今后研究的发展方向。将数学模拟与土壤重金属信息系统及地理信息系统GIS的有机结合,将有可能为环境保护和农业决策提供新的重要依据。     

渝黔高速公路綦江段两侧农地土壤重金属空间分布特征研究

选择渝黔高速公路綦江段沿线,设置6个农地区域进行土壤重金属(As、Cd、Cr、Cu、Hg、Ni、Pb、Zn)监测,并进行空间特征分析。结果表明:渝黔高速公路綦江段邻域土壤表层As、Cd、Cr、Cu、Hg、Ni、Pb、Zn含量平均值分别为3.40,0.24,59.37,21.81,0.064,25.41,24.75,68.81mg·kg-1;水平方向上,土壤随着高速公路的外延,As、Cr、Ni、Zn含量整体呈下降趋势,Hg则反之,Cd、Cu、Pb相对稳定;垂直方向上,重金属含量随深度增加而降低,即表土层心土层底土层;以表层土为基础,可以确定项目区实际安全种植距离为远离高速公路150 m左右。土壤样品Cd部分超标,超标率为17.65%。     

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.