发育于石英岩之上的表土磁学性质及其环境磁学意义

通过对石英岩及发育于石英岩之上表土的磁化率(X)、频率磁化率(Xfd)、等温剩磁(IRM)、非磁滞剩磁(ARM)、κ-T曲线等磁学参数测定和石英岩显微镜下观察,结果表明,石英岩中磁性矿物含量极少;表土中含磁铁矿、磁赤铁矿、铁的氢氧化物等磁性矿物,磁性矿物主要以稳定单畴(SSD)和超顺磁性颗粒(SP)形式存在,磁赤铁矿是石英岩在成土过程中形成的次生矿物.表土磁性增强,说明石英岩的磁性对表土磁性影响甚小,而成土作用对表土磁性增强起到了重要作用.表土的磁化率值和磁赤铁矿含量都反映了成土作用的强弱.     

土壤磁性矿物的多元成因——成土作用成因与人为污染成因磁性的区分

对黄土高原古土壤和上海市城市土壤磁性特征进行比较,研究和区分土壤磁性的多元成因。结果表明,黄土高原古土壤磁化率(χlf)平均值为108×10-8m3kg-1;频率磁化率(χfd%)平均值为11·4%,且χlf与χfd%呈极显著正相关性,表明风化成土作用形成超细顺磁颗粒(SP)是其磁性增强的主要原因。χlf与游离态铁(Fed)、铁游离度(Fed/Fet)和黏粒含量相关性达极显著水平,也说明古土壤磁性增强与风化成土作用有关。上海城市土壤χlf异常增强,变化范围为127～1959×10-8m3kg-1,χfd%2·0%,表明其不含SP,磁性增强并非由于风化成土作用,应与人为污染有关。非滞后剩磁(χarm)、非滞后剩磁/饱和等温剩磁(χarm/SIRM)、非滞后剩磁/磁化率(χarm/χlf)和饱和等温剩磁/磁化率(SIRM/χlf)等参数及组合的研究表明,城市土壤磁性矿物占主导的是多畴(MD)和稳定单畴(SSD)颗粒;而古土壤磁性矿物中占主导的是SP颗粒。软等温剩磁(SOFT)、硬等温剩磁(HIRM)、软磁百分含量(SOFT%)、硬磁百分含量(HARD%)、IRM300mT/SIRM(F300mT)等磁性参数的研究表明,城市土壤矫顽力低,软磁组分高,以铁磁性矿物为主导;黄土高原古土壤也以铁磁性矿物为主导,但HARD%通常高于城市土壤。用磁学参数及组合,能较有效分辨土壤磁性的风化成土作用成因或人为污染成因。     

新疆喀纳斯景区表层土壤磁学特征及环境意义

为探究环境磁学方法在景区土壤污染监测中的可行性,以新疆5A级景区喀纳斯为研究区域,采集表层土壤样品72个,并对其进行系统的环境磁学分析。结果表明:喀纳斯景区土壤磁性矿物平均含量较高,磁学矿物主要由亚铁磁性矿物构成,并含有少量的不完全反铁磁性矿物。磁晶颗粒主要为粗颗粒多畴,同时存在较少的超顺磁颗粒。磁参数空间分布表明,磁性矿物含量参数(χLF、SIRM、SOFT、HIRM)在湖口旅游区表现出高值,新村、老村和旅游接待地呈现相对低值;其他参数(χFD%、S-ratio、SIRM/χLF)空间分布规律与含量磁性参数基本呈相反趋势;研究区的磁性高值点分布与景区人类活动密集区、建筑物及道路的分布具有一致性;湖口旅游区较高的磁性值主要与较强的自然成土作用有关,其他区域的磁性高值点主要受旅游活动的影响。因此,借助土壤磁学方法能够有效区分和圈定景区土壤人为污染范围,为景区土壤污染防治和旅游规划提供参考依据。     

上海市杨浦区表土重金属污染的磁学响应

[目的]揭示上海市杨浦区土壤重金属污染情况,为环境磁学在城市表土重金属污染的应用提供科学依据。[方法]结合磁学方法与传统化学方法,对杨浦区5个功能区内的17个表土样品进行磁学特征和重金属浓度的分析。[结果]杨浦区表土磁化率值平均值为2.42×10~(-6) m~3/kg,磁性特征以低矫顽力的亚铁磁性矿物为主导,颗粒较粗。除频率磁化率外,磁学参数整体呈现工业区与交通区值较高的特点;重金属Zn,Pb,Cu,Cr浓度值高于背景值,且高值集中在工业区、交通区、居住区,污染负荷指数(PLI)的值为1.962,属于轻度污染。除工业区外,各功能区之间重金属含量与磁学参数的相关性较好(p0.05),磁化率(χlf)、饱和等温剩磁(SIRM)、硬剩磁(HIRM)对杨浦区表土重金属含量有良好的指示作用。[结论]环境磁学方法可以快速简便地提供城市污染信息。     

太白山不同海拔植被带土壤矿物磁性变化规律研究

土壤矿物磁性对环境变化具有重要的指示意义。然而,有关中国中东部东亚季风区内土壤矿物磁性随海拔高度的变化规律的研究和讨论尚不多。我们获取了太白山不同海拔高度5个典型植被带下的表土及土壤剖面样品,测量了这些样品的磁化率(χ_(lf))、频率磁化率(χ_(fd))、非磁滞剩磁(ARM)、饱和等温剩磁(SIRM)、反向磁场等温剩磁(IRM_(-300m T)),探讨了不同植被带中土壤矿物磁性特征及其变化。结果显示:(1)不同植被带下,表土矿物磁性差异显著,χ_(lf)、ARM、SIRM之间表现出良好的相关性,随海拔升高呈降低趋势,而IRM_(-300m T)/SIRM随海拔升高而升高。(2)除栓皮栎林外,其他植被带处的土壤剖面χ_(lf)、χ_(fd)、ARM、SIRM随剖面深度加深而降低,IRM_(-300m T)/SIRM随深度加深而升高;此外,低海拔的栓皮栎林与锐齿栎林处土壤剖面磁性的各个指标远高于高海拔土壤剖面磁性指标。(3)表土总体磁性矿物浓度,较细磁畴的SSD颗粒及亚铁磁性矿物浓度与不同植被带所处温度呈现正相关关系,而与其土壤中的有机质含量呈负相关,但受降雨及坡度影响较小。     

福建周宁黄红壤的磁学特征及其磁性矿物转化

对我国亚热带地区发育于花岗岩之上的一个黄红壤剖面进行了系统的环境磁学测量,对土壤样品的磁化率、等温剩磁、磁滞回线等常温磁学参数进行测量,对代表性样品进行热磁分析,并结合色度、常量地球化学元素和漫反射光谱参数,探讨亚热带黄红壤的磁性特征,以及在相对湿冷的气候条件下,黄红壤中的磁性矿物具有怎样的转化规律。结果表明：亚热带黄红壤中强磁性矿物为亚铁磁性的磁铁矿、磁赤铁矿,弱磁性矿物为反铁磁性的赤铁矿、针铁矿。随着成土作用/风化作用增强,磁性矿物颗粒变细。母质和气候条件是影响区域磁性差异的重要因素,次生磁性矿物（特别是赤铁矿与针铁矿）的含量主要受气候条件控制。在相对湿冷的气候条件下,磁性矿物的转化以强磁性的磁铁矿与磁赤铁矿转化为弱磁性的赤铁矿与针铁矿为主。气温（而非降水）是湿润亚热带地区花岗岩风化壳上发育土壤中针铁矿和赤铁矿含量以及相对比例的主导影响因素。     

福建周宁黄红壤的磁学特征及其磁性矿物转化

对我国亚热带地区发育于花岗岩之上的一个黄红壤剖面进行了系统的环境磁学测量,对土壤样品的磁化率、等温剩磁、磁滞回线等常温磁学参数进行测量,对代表性样品进行热磁分析,并结合色度、常量地球化学元素和漫反射光谱参数,探讨亚热带黄红壤的磁性特征,以及在相对湿冷的气候条件下,黄红壤中的磁性矿物具有怎样的转化规律。结果表明：亚热带黄红壤中强磁性矿物为亚铁磁性的磁铁矿、磁赤铁矿,弱磁性矿物为反铁磁性的赤铁矿、针铁矿。随着成土作用/风化作用增强,磁性矿物颗粒变细。母质和气候条件是影响区域磁性差异的重要因素,次生磁性矿物（特别是赤铁矿与针铁矿）的含量主要受气候条件控制。在相对湿冷的气候条件下,磁性矿物的转化以强磁性的磁铁矿与磁赤铁矿转化为弱磁性的赤铁矿与针铁矿为主。气温（而非降水）是湿润亚热带地区花岗岩风化壳上发育土壤中针铁矿和赤铁矿含量以及相对比例的主导影响因素。     

乌鲁木齐城市土壤磁性的空间变异特征研究

在乌鲁木齐市,按不同用地类型和空间分布的均匀性,采集45个表土样品。分析了土地利用类型引起的市、郊区土壤磁性参数的差异,研究了土壤磁性参数空间变异性和分布特征,并初步探讨了其人为影响因素。结果表明:除了χFD以外,市区土壤χLF、Soft IRM和HIRM均值高于郊区。研究区土壤以亚铁磁性矿物主导,并伴有少量不完全反铁磁性矿物,市区土壤超顺磁性矿物颗粒含量低于郊区。土地利用类型是导致市、郊区土壤磁性参数差异的重要因素。从变异系数看,4种磁性参数都属于中等变异程度。空间变异性分析表明,各磁性参数的最优拟合模型是球状和指数模型,变程介于15~18km之间。从Q值结果看,χFD、Soft IRM属于高度空间变异性,χLF为中度变异性,HIRM变异程度最低。空间分布特征表明,χLF、Soft IRM值基本以工业区为中心,向外围递减。χFD分布趋势大致与其他参数相反。HIRM分布呈东、西部高,中部低且向南北方向递减的趋势。人为因素是影响乌鲁木齐市土壤磁性空间变异的关键因素。     

安徽凤阳石英岩发育土壤的磁学性质及环境磁学意义

通过对安徽凤阳石英岩发育土壤典型剖面的磁学参数测量,结果表明,A层和B层中的磁性矿物含量明显高于C层,且A层和B层中磁性矿物的粒度明显比C层细.C层的磁学性质由磁铁矿主导,A层和B层的磁学性质由磁赤铁矿主导.磁赤铁矿是石英岩在成土过程中形成的次生矿物.土壤中磁赤铁矿的出现及含量的变化指示成土作用的强弱.石英岩的磁性对土壤的磁性影响甚小,而成土作用和生物作用对土壤磁性增强起到了主要作用.     

贵州碳酸盐岩发育土壤磁学性质及其发生机理

本文对贵州碳酸盐岩发育土壤的磁化率、磁化率频率系数和等温剩磁等磁学参数的系统测定以及磁性矿物研究表明，碳酸盐岩发育土壤磁学性质及其变化特征主要受成土地球化学作用和环境影响，具有十分重要的环境指示意义。本文在采用高梯度磁性分离土壤中氧化铁矿物基础上，综合运用Ｘ射线衍射分析、电子探针分析、透射电镜和穆斯堡尔谱等方法，讨论了碳酸盐岩发育土壤中磁性矿物的形成机理。     

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.