山西耕作土壤样品磁性空间分异及其环境意义

本文分析了山西高原土壤耕作层(0-20cm)25个样品的磁性,用GIS空间分析方法,得出土壤磁化率平面分布等值线图和空间三维模型。磁化率空间分布机理如下:首先,强烈的人为影响使土壤中磁性矿物人为来源占有重要地位。第二,土壤磁性矿物以亚铁磁性的磁铁矿和磁赤铁矿为主导。第三,土壤磁化率极值差及其与母质之间的差异均受广泛而较均一的黄土母质的影响。第四,晋西北和晋中等区域出现土壤磁化率高值区域。第五,人为作用强烈影响掩盖了气温、降水等气候因子对土壤磁化率的作用。     

川中丘陵县域土壤碳氮比空间变异特征及其影响因素

以四川仁寿县为案例区,通过实地采样分析了该紫色丘陵区县域尺度上土壤碳氮比的空间变异特征及其影响因素.结果表明:研究区表层土壤碳氮比(C/N)在4.84~21.79之间,平均值为11.93,变异系数26.3%,属中等程度的空间变异.半方差分析表明,土壤C/N的块金效应为73.0%,其空间分布受结构性因素和随机因素的共同影响,但受随机性因素的影响更大;土壤C/N的空间分布特征表现为西北和东南高、中部低的趋势,大部分区域土壤C/N处于10.0~13.5之间.成土母质、土壤类型、地形和土地利用方式对土壤C/N的影响显著(P<0.05);地形因子中高程和坡度与土壤C/N呈显著正相关关系(P<0.05),成土母质可解释土壤C/N 8.7%的空间变异,土类、亚类和土属的解释能力分别为3.8%、5.0%、8.7%,地形因子的解释能力为0.8%;土地利用方式对土壤C/N空间变异影响程度最高,达到23.9%,是调控该区域土壤C/N的重要因素.     

四川盆地西缘浅层地下水铁、锰含量的空间变异特征

以四川盆地西缘低山丘陵区典型县--名山县为例,采用地统计分析方法,研究了四川盆地西缘低山丘陵区浅层地下水铁、锰含量的空间变异特征.结果表明,研究区浅层地下水铁含量变异较大,局部区域超标现象较为严重,42.86%的样点未达到欧盟生活饮用水水质标准(<0.2 mg/L),25%的样点未达到我国和美国生活饮用水水质标准(<0.3 mg/L);锰含量总体水平较低,其中94.64%的样点达到我国的生活饮用水水质标准(<0.1 mg/L),所有样点均达到世界卫生组织规定的生活饮用水水质标准(<0.4 mg/L).研究区浅层地下水中铁、锰含量空间分布特征基本一致,均呈现出从东北向西南逐渐降低,至名山县城附近又有所上升的趋势,高值区主要出现在东北部一带,低值区主要出现在中南部一带.研究区地下水中铁、锰含量分布特征与区域土壤母质、土壤类型、人为活动等因素密切相关, 其中受土壤母质和土壤类型的影响尤为明显.统计结果表明,第四系更新统冰碛物及冰水沉积物(Q2fgL)分布区域地下水铁、锰含量显著高于白垩系夹关组(K2j)、灌口组(K2g),第三系名山群(K1～2mn)等紫色岩分布区域;黄壤下浅层地下水铁、锰含量显著高于紫色土.     

呼伦贝尔草原人为火空间分布格局

人为草原火及其影响因素的空间分布格局与相关关系研究对于草原火发生、草原火管理等研究具有重要的意义.应用Ripley's K函数对呼伦贝尔草原1976-1996年间发生的人为草原火进行了空间统计分析,确定人为草原火空间分布在年内主要发生月份和年际间均呈聚集分布;应用Kernel密度函数对人为草原火及其影响因素居民点、道路和农田的空间分布密度进行了研究,结果表明呼伦贝尔草原人为火分布广泛,热点区域主体在123.05-124.82°E、48.25-50.21°N之间;居民点、农田空间分布密度的热点区域主要分布在东部和中部地区,道路的分布密度较农田和居民点分布更加均匀.人为草原火空间分布密度与居民点、道路和农田的空间分布密度呈显著性正相关,其Pearson相关系数依次为0.448、0.236、0.602 (P＜0.001),火源因素(居民点、道路、农田)的空间分布格局是呼伦贝尔草原人为火空间分布格局的主要影响因素.     

三峡库区杉木马尾松混交林土壤C、N空间特征

自然和人为因素的强烈干扰直接影响三峡库区土壤C与土壤N贮量与分配特征.杉木马尾松混交林是三峡库区主要植被类型之一且分布面积最大,因而研究其不同干扰程度下土壤C、N分布特征对于准确评估三峡库区土壤C与N贮量具有重要意义.2008年秋季与2009年春季,采用对角线法取样法方法对三峡库区不同干扰条件下杉木马尾松混交林0-20cm土壤层中土壤C、N含量的季节与空间分布特征进行研究.结果显示,土壤N含量季节差异性显著,土壤C含量仅在人为严重干扰下呈季节性差异显著(P＜0.05);干扰强度对秋季土壤C、N影响显著(P＜0.05).土壤C、N与土壤含水量、pH值均存在显著相关关系(P＜0.01).研究区酸性土壤(pH值介于4.59-5.15)增加了土壤C、N的固定与积累.土壤碳氮比与表层土壤矿质化程度和人为干扰有关,强烈人为干扰和地表状况减弱了土壤C、N空间相关性.地统计学分析表明,半方差函数的曲线球状模型较好地反映了无人为干扰条件下土壤C、N的空间结构特征.土壤C、N空间结构变化与灌木层盖度、坡度、季节及人类干扰有关.     

不同母质温带草地植物群落多样性对人为干扰的响应

本研究以赛罕乌拉保护区2种不同土壤母质(黄土和沙母质)与3种利用方式(围栏打草、季节性放牧和自由放牧)草地为对象,基于群落组成调查数据,计算人为干扰指数与物种多样性指数,研究草地植物群落物种多样性与草地退化程度间的关系。结果表明: 土壤母质与人为利用方式的差异使草地处于不同的退化状态,黄土与沙母质类型草地退化程度均随人为利用强度的增加而上升,且当人为利用方式相同时,黄土母质草地人为干扰指数(均值1.21)比沙母质草地(均值1.48)低。各样地物种多样性指数总体随土壤母质的砂质化和人为利用强度的增加而下降,其中Margalef丰富度指数为1.57～4.27,Shannon多样性指数为1.16～2.39,Simpson优势度指数为0.76～0.87,Pielou均匀度指数为0.71～0.80。随着人为干扰指数增加,丰富度指数、多样性指数和优势度指数均下降,而均匀度指数有上升趋势。过度放牧对2种土壤母质草地均会造成严重威胁,黄土与沙母质草地最适宜的利用方式分别为围封打草和季节性放牧。在今后生物多样性保护的实施过程中,需兼顾草地不同土壤母质与人为利用方式的影响,针对不同土壤母质条件规划不同的草地利用方式,实现因地制宜的草地恢复与管理。     

汉江上游金水河流域土壤常量元素迁移模式

本研究旨在通过研究汉江上游金水河流域土壤无机物风化与有机物分解代谢相互关系,初步揭示研究流域尺度范围内常量元素的生物地球化学循环和空间分异的主驱动因子。通过野外调查与取样、实验室样品检测和空间模拟分析,得到以下的研究结果：一、金水河流域的土壤风化已基本完成早期阶段的去Ca,Na风化阶段,进入K风化阶段;二、土壤风化内外因素（如,土壤母质、矿物结构、温度、降水、风和重力等）作用下形成了明显的空间差异,流域内属于典型的林下有机质积聚过程,土壤矿物中的硅酸盐矿物风化分解和淋溶作用较强;三、土地利用方式改变了土壤有机质分布模式,不合理的人类活动造成农田耕作层和森林枯枝落叶层的有机质减少,土壤腐殖酸的减少影响土壤矿物风化和元素地球化学行为,对农业持续发展形成负面的影响。流域作为南水北调中线水源地,保护森林植被及枯枝落叶层对土壤涵养水分有着重要意义。     

基于样带的滨海盐碱地土壤养分和盐分的空间变异

在黄河三角洲北部刁口黄河故道盐碱地设置一条南北土壤样带,采用地统计学方法分析土壤养分指标(有机质、全氮、有效磷、速效钾)和全盐含量的空间分布规律及其影响因素.结果表明:研究区土壤有机质、全氮、有效磷、速效钾和全盐含量的块金系数分别为0.38、0.40、0.50、0.32和0.34,5个土壤指标均具有中等的空间相关性;样带上土壤有机质和全氮含量的分布趋势基本一致,土壤速效钾与全盐含量的分布具有很强的相关性,土壤有效磷含量呈波动式的空间分布.综合土壤有机质和全盐含量,将样带土壤划分为盐大肥低型、盐大肥高型、盐小肥高型3种类型.研究区各土壤指标的空间分布格局与成土母质、土地利用方式、距海距离、道路阻隔等因素密切相关.     

克拉玛依城市土壤磁化率、 有机质和 pH 值的特征及关系研究

选取了克拉玛依市建成区不同土地利用类型下的 56 个土壤样品, 分析了土壤样品的磁化率、有机质与 pH 值特征,并探讨了他们之间的相互关系, 其目的是揭示快速的城市化进程对土壤特性的影响。研究结果表明: 克拉玛依市土壤中磁性颗粒主要源于人类活动产生的多畴(MD)粗颗粒, 不同土地利用类型下土壤磁性矿物含量各异; 土壤有机质总体含量偏高,不同用地类型中有机质含量具有差异性, 主要是受当地的植被覆盖率和人类活动强度的影响; 土壤 pH 值平均值为 7.54, 表明克拉玛依市土壤总体偏碱性, 不同土地利用类型下土壤 pH 值存在差异性, 通过方差分析发现: 交通运输用地、未建设用地与居住用地之间 pH 值具有显著性差异。克拉玛依总体土样磁化率与有机质、 pH 值均呈正相关关系, 但在不同土地利用类型下三者之间呈现不同程度的相关性, 很好的显示了在快速的城市化过程中人类活动对自然成土过程的过度干扰。     

桂西北石漠化空间分布及尺度差异

运用研究区TM影像,结合GIS&RS技术等手段建立桂西北石漠化基础数据,通过多元逐步回归、冗余分析(RDA)研究了不同尺度上桂西北石漠化与相关因子的关系,探索石漠化的空间分布规律及尺度差异性.结果表明,自然因素对石漠化分布的影响大于人为因素,人为作用的影响随着石漠化等级的提高而增大.石漠化空间分布的控制因子存在尺度转移.在县级尺度上,土壤类型起决定性作用,石质土对石漠化的贡献率最大;在乡镇尺度上,地形与土地利用类型的影响更重要,石漠化因子的重要性排序为山地比例>平均高程>裸岩地>石灰土>未利用地>石质土.两个尺度上,极强度石漠化均表现为人为活动的结果.由于石漠化空间分布的控制因子存在尺度差异,部署石漠化恢复治理任务时,需遵从其空间分布的规律.     

扬（州）-瓜（州）公路交通肇事刑事侦破中环境磁学的应用

本文在土壤学方法的基础上,尝试应用环境磁学手段,帮助侦破一起道路交通刑事案件.实践表明：环境磁学在刑事案件的侦破中,对于土壤和沉积物样品的鉴别分析,具有独特的意义.     

扬( 州) - 瓜( 州) 公路交通肇事刑事侦破中环境磁学的应用

本文在土壤学方法的基础上,尝试应用环境磁学手段,帮助侦破一起道路交通刑事案件。实践表明:环境磁学在刑事案件的侦破中,对于土壤和沉积物样品的鉴别分析,具有独特的意义。     

Mononuclear and polynuclear halide and nitrate Cu(II) compounds with 1,4,5-triazanaphthalene as a ligand: Characterization, magnetism and X-ray structures

Using the ligand 1,4,5-triazanaphthalene (abbreviated as tan) in combination with Cu(II) salts, three mononuclear compounds, Cu(tan)₂Cl₂ (1), Cu(tan)₂Br₂ (3), Cu(tan)₂(NO₃)₂ (5) and three polynuclear compounds, [Cu(tan)Cl₂]_n (2), [Cu(tan)Br₂]_n (4), [Cu(tan)(NO₃)₂]_n (6) have been synthesized and characterized by UV-Vis, EPR, FTIR and Far-FTIR spectroscopies. The crystal structures of compounds 1, 3, 5 and 6 are reported, as well as that of the dioxane adduct of compound 4, [Cu(tan)Br₂(C₄H₈O₂)](C₄H₈O₂) (4A).The structure of (2) was solved by X-ray powder diffraction. The coordination geometry around the Cu(II) atoms is tetrahedral for (1) and (3), square-pyramidal for (4A) and distorted octahedral for (5) and (6). Magnetic susceptibility measurements on the polynuclear compounds revealed weak antiferromagnetic interactions between the Cu(II) atoms with interaction constants (J) of J = −9.1 and −10.5 cm⁻¹, for 4 and 6, respectively. For compound 2 two options for possible interactions were considered, with interaction constants which vary for J_rung −22.0 to −13.5 cm⁻¹ and J_rail −19.6 to −17.0 cm⁻¹. These figures are discussed in the light of relevant structural parameters and literature.     

Structural and magnetic properties of Ln(III) complexes with diimines and crotonato as a bridging ligand

Five new lanthanide complexes displaying crotonato bridges have been prepared: [Gd₂(crot)₆(H₂O)₄] · 4(bpa) (1); [Ho₂(crot)₇]_n · (Hbpa) (2); [Gd₂(crot)₆(bipy)₂] (3); [Ho₂(crot)₆(bipy)₂] (4) and [Nd₂(crot)₆(H₂O)₃]_n (5), where bipy=2,2^′-bipyridine; bpa=di(2-pyridyl)amine; crot=crotonato. The compounds were characterized by magnetic susceptibility measurements and their crystal structures were determined by single crystal X-ray diffraction. These studies showed complexes 1, 3 and 4 to be dimers while structures 2 and 5 are polymeric in nature.     

Synthesis, structure, and magnetism of a binuclear Co(II) complex of a potentially bis-tridentate verdazyl radical ligand

The synthesis, structure, and magnetic properties of a dinuclear Co(II) complex of a tridentate verdazyl radical are presented. The reaction of a tetrazane containing a 4,6-bis(2-pyridyl)-pyrimid-2-yl substituent with cobalt chloride hexahydrate in aerated solution leads to in situ oxidation of the tetrazane to a verdazyl radical which is coordinated to Co(II) in a tridentate manner. The second tridentate coordination site of the verdazyl remains vacant. The crystal structure reveals the complex to be dimeric, with the cobalt ions linked by two bridging chlorides. The structure of Co₂Cl₂ core is highly asymmetric, with two short (2.3317 Å) and two long (2.744 Å) Co-Cl bonds. There are relatively short intermolecular contacts between coordinated verdazyl radicals in the solid state. Magnetic susceptibility data from 2 to 300 K suggest intramolecular ferromagnetic interactions, and modeling of the high-temperature data produced a best fit with J_Co-verdazyl of +20 cm⁻¹.     

The effects of buried magnets on colonies of Amitermes spp. building magnetic mounds in northern Australia1

ABSTRACT Unlike four control colonies of Amitermes which built normal, north-south oriented 'magnetic' mounds in northern Australia, four young colonies failed after exposure to experimental alteration of the earth's magnetic field. In November 1979, bar magnets were buried on either side at the base of each of three new nests of Amitermes laurensis Mjoberg and one new colony of A.vitiosus Hill. As controls, non-magnetized iron bars were disposed similarly in relation to three new nests of the former species and one of the latter. In September 1986, all four control nests had grown normally. However, not one of the treatment colonies survived and from what remained of the former nest in each case it is clear that the demise of the colonies occurred soon after the magnets were placed. We conclude that the failure of these colonies was the result of the changed magnetic environment. Whether 'magnetic' termites use magnetoperception as a cue to achieve their spectacular north-south orientation remains unknown, but the results of this field experiment weigh more for than against this possibility.     

1,1′-Diethyl-2,2′,3,3′,4,4′,5,5′-octamethylferrocenium tetracyanoethylenide, [Fe(C5EtMe4)2][TCNE], a charge-transfer salt magnetic solid with a novel structural motif

1,1′-Diethyl-2,2′,3,3′,4,4′,5,5′-octamethylferrocene has been utilized as a one-electron donor in the synthesis of a tetracyanoethylene charge-transfer salt, [Fe(C₅EtMe₄)₂]⁺[TCNE]⁻. Structural characterization shows that it adopts an arrangement of anions and cations completely different from the usual π stacking seen in analogous decamethylferrocenium compounds. The TCNE radical sits along side of the ferrocene, nearly perpendicular to the planes of the C₅ rings. The nearly square geometry of the TCNE anion creates disorder over two orientations. [Fe(C₅EtMe₄)₂]⁺[TCNE]⁻ is a simple paramagnet exhibiting neither long-range magnetic order nor slow paramagnetic relaxation to the lowest measured temperatures (ca. 1.8 K) as determined by both ac and dc magnetic susceptibility and Mössbauer spectroscopy (ca. 1.3 K).     

New dinuclear Co(II) and Mn(II) complexes of the phenol-based compartmental ligand containing formyl and amine functions: structural, spectroscopic and magnetic properties

The phenol-based compartmental ligand Hpy2ald contains a tridentate amino arm and a weak donor aldehyde group at the 2^′ and at the 6^′ positions of the phenol ring, respectively. This ligand reacts with cobalt(II) perchlorate, cobalt(II) tetrafluoroborate and manganese(II) perchlorate, yielding dinuclear complexes, where two metal ions are doubly bridged by two deprotonated cresolate moieties. The coordination environment around the metal ions is then completed to a very distorted octahedron by three nitrogen donor atoms from the pendant amino arm and the oxygen atom of the aldehyde group. The crystal structures of the complexes, their spectroscopic and magnetic properties are reported.     

Synthesis, structure, magnetic and electrochemical properties of an oxydiacetate iron(II) complex

Compound [{Fe(oda)(H₂O)₂} · H₂O]_n (1) [oda=O(CH₂COO)₂ ²⁻] has been obtained by reaction of FeCl₂ · 4H₂O with a 1:1 mixture of O(CH₂COOH)₂ and Na₂CO₃ in water. The structure is polymeric with concatenated {Fe(oda)(H₂O)₂} units extended in one direction. Each iron centre is six-coordinated by the tridentate planar oda ligand, two mutually trans water molecules and one oda oxygen atom from an adjacent {Fe(oda)(H₂O)₂} unit. Complex 1 is isomorphous with cobalt and zinc analogues. Magnetic susceptibility measurements down to 2 K showed high-spin non-correlated Fe(II) ions with a typical Curie-Weiss behaviour. Differential-pulse voltammetry establishes a value of 0.488 V versus NHE for the Fe(III)/Fe(II) redox potential of this iron complex in 0.25 mol dm⁻³ NaNO₃.