广西钟山县主要农用地土壤硒的地球化学特征

通过对钟山县主要农用地的土壤硒进行系统调查,结果显示:研究区表层土壤硒含量平均值为0.41mg/kg,富硒土壤分布范围广,足硒和富硒土壤占总面积的90.13%;土壤类型中,黄壤中的硒含量最高,平均值为0.52mg/kg,洪积土中的硒含量最低,平均值为0.34mg/kg;硒在酸性土壤中的含量最高,次为中性土壤,最低为碱性土壤;土壤中硒含量的主要影响因素为地层、成土母质、铁铝含量和pH值;研究区土地质量良好,富硒农产品主要为水稻和玉米,富硒土地资源具有良好的开发前景。     

土壤硒含量影响因素及富硒土地资源区划研究——以湖北恩施沙地为例

硒是人体必需的微量元素之一。为了研究土壤硒含量分布特征及其主要影响因素,并对富硒土地资源进行安全利用区划,本研究在恩施市沙地乡系统地采集并分析化验了199件表层土壤样,60件农作物样。分析了玉米籽实及对应的表层土壤中硒含量等地球化学参数的相关性,建立了玉米籽实硒元素吸收模型。结果表明：研究区表层土壤硒含量变化范围为019~1557 mg·kg-1,算术平均值为188 mg·kg-1,远超过湖北省及全国表层土壤硒含量水平,足硒、富硒土壤面积占研究区总面积的8443%;表层土壤硒含量分布受控于地质背景,不同地质背景的表层土壤硒含量分布存在较大差异,二叠系茅口组地层表层土壤硒含量显著高于其他地层分布区域;土壤有机碳含量及海拔高度是影响研究区表层土壤硒含量的重要因素;农作物硒含量变化范围较大,其中处于富硒水平的农作物所占比例最大,为4322%;研究区富硒土地面积和潜在富硒土地面积分别占研究区总面积的6533%和2312%。     

安徽贵池地区富硒土壤地球化学特征及开发利用潜力

为了解安徽贵池地区富硒土壤特征与潜力,服务当地富硒土地资源开发,选择贵池西部开展土壤地球化学测量试验,探讨Se、I等有益元素的富集特征、成因及潜力,Cd、As等有害元素的超标特征及成因等,结合研究区土壤中有益、有害元素特征,讨论富硒土地资源及其开发优势。发现表层和深层土壤中Se等有益元素含量总体较高,其中Se含量达到富硒土地标准的表层土壤点位占全部样品点位的76%;表层土壤中Cd含量超标的点位占48%,其他有害元素仅个别点位超标,Cd是制约该地区富硒土地资源开发的主要不利因素。在研究区圈定了61.4 km2的富硒土地资源,认为研究区东部土壤富硒的物质来源是二叠系灰岩,可以利用当地灰岩提升富硒土地资源品质,降低生态风险。     

福建省龙海市表层土壤硒含量及影响因素研究

在龙海市土壤地球化学调查数据基础上,开展土壤硒含量特征、影响因素分析等项研究工作,可为研究区富硒土地资源开发提供依据。本文通过采用原子荧光光谱法(AFS)对福建省龙海市表层土壤4394件样品硒全量进行了分析测试,结果表明:龙海市表层土壤的硒含量为0.031~2.361 mg/kg,平均值为0.354mg/kg,足硒、富硒土壤面积占全地区面积的88.69%。同时发现,成土母质、土地利用方式、土壤pH、有机质含量以及海拔高度是影响龙海市土壤硒含量的重要因素。火山凝灰岩区、花岗岩区成土母质发育的土壤硒含量较高;在不同土地利用方式中,林地土壤的硒含量最高,园地、耕地土壤的硒含量适中;土壤硒含量与有机质含量、海拔高度呈正相关,与pH呈负相关,说明在酸性、富含有机质的土壤环境中硒元素易于富集,尤其是高海拔的山地丘陵区土壤中硒的富集作用更加明显。本研究成果对龙海市土地的合理规划利用、富硒产业的科学发展具有重要价值。     

承德市富硒土壤区镉的地球化学特征及生态风险评价

硒是人体必需的生命元素,开发富硒农产品是提升人体硒摄入的安全有效途径,富硒土地资源是开发富硒农产品的基础。然而,近年来全国开展的多目标地球化学调查发现,富硒土壤中重金属元素镉通常较高,不利于富硒土地开发利用,因此,研究富硒土壤区镉的地球化学特征和生态风险状况对于富硒土地开发具有重要的指导意义。文章对承德市富硒土壤区表层土壤中主要的重金属元素镉的地球化学特征及生态风险进行评价,旨在为承德市富硒土地开发利用提供科学依据。采用“七步提取法”研究了表层土壤镉的形态特征。同时,配套分析了苹果、玉米样品中的重金属元素镉的含量,以了解其生物有效性。结果显示:承德市富硒土壤区表层土壤镉在全区均较富集,在新积土和中性粗骨土、水田中显著富集。研究区圈定了4处镉轻度污染土壤,均在表层土壤镉的高值区。表层土壤镉形态平均含量大小顺序为:水溶态 < 离子交换态 < 强有机结合态 < 腐殖酸结合态 < 铁锰氧化物结合态 < 碳酸盐结合态 < 残渣态,生态风险相对较低。表层土壤镉未对苹果和玉米样品产生影响,苹果和玉米中镉均不超标。承德市富硒土壤区表层土壤镉的生态风险较低,暂不影响承德市富硒土地开发利用。     

江西赣州梓山地区富硒土壤重金属元素安全性评价

在江西梓山地区采集土壤样712件、水稻样46件,分析该区土壤、水稻中As、Cd等重金属元素含量及其在土壤—水稻系统中的安全性。研究区土壤环境质量总体优良,清洁和较清洁土壤图斑面积为11 883.06hm2,占全区面积的96.82%;轻微污染的土壤图斑面积为368.66hm2,占全区面积的3.00%;重金属污染的土壤图斑主要分布于富硒土壤区。水稻中As等重金属元素含量较低,均符合国家食品安全标准。水稻对As等元素的吸收富集能力受其土壤总量及其有效性制约,而重金属元素的生物有效性主要受重金属总量与TFe2O3的控制。研究区土壤脱硅富铁铝的特征表明,该区土壤As等重金属元素的生物有效性较低,可开发富硒水稻。     

广西三江县土壤硒含量分布特征及其影响因素研究

以广西三江县土壤为研究对象,采集了表层土壤样2 751件和土壤垂向剖面样180件,测定了土壤中硒的含量。利用多元统计分析、地统计学法、GIS空间分析技术和Pearson相关性分析法研究了土壤硒的含量特征和影响因素。结果表明:研究区表层土壤硒平均含量为0.63 mg/kg,变化范围为0.10~14.41 mg/kg。研究区土壤硒资源丰富,足硒和富硒土壤面积为95.87%。土壤硒含量的分布主要受到地质背景的控制,不同成土母岩形成的表层土壤硒含量存在较大差异,寒武系以黑色岩系为母质的土壤硒含量最高,平均含量达2.58 mg/kg,变化范围为0.31~14.41 mg/kg。不同土壤类型中,黄壤硒含量最高,平均含量达0.75 mg/kg,变化范围为0.24~2.07 mg/kg,水稻土硒含量最低,平均含量为0.51 mg/kg;不同土地利用类型土壤硒含量差异较大,除水田为基本自然状态以外,其余地类均呈现富集。研究区表层土壤硒含量总体上受控于深层土壤硒含量,成土过程中表层土壤硒含量发生了次生富集。同时土壤pH、Corg、P、S、Al₂O₃、TFe₂O₃含量和CIA等对土壤硒含量的分布也有一定的影响。     

赣南地区土壤硒元素地球化学特征及其影响因素研究：以青塘—梅窖地区为例

以赣南青塘—梅窖地区为典型区开展详细的调查研究工作,共采集了表层(0~20 cm)土壤样品889件,农作物样品72件。系统地分析了土壤及农作物中硒元素含量的空间分布特征及其与成土母质、土地利用类型和土壤理化性质的关系。结果表明：研究区土壤硒平均含量为044 mg·kg-1,其中面积比例为4859%的土壤硒含量处于足硒状态,面积比例为4286%的土壤硒含量处于富硒状态。在空间分布上,缺硒和潜在硒不足土壤仅呈零星分布。表层土壤硒含量在一定程度上继承了成土母质硒的含量,不同的土地利用类型土壤中硒含量也存在一定的差异。土壤有机质含量与硒含量呈显著正相关关系,与土壤pH值没有相关性。花生和水稻富硒率较高,其中花生和早稻含量均符合国家食品安全标准,仅晚稻存在一定的重金属超标现象。通过对比富硒土壤和不富硒土壤中晚稻重金属含量的超标率、硒的富集系数和含量,发现在富硒区晚稻中重金属的超标率远远低于非富硒区,说明土壤硒元素会在一定程度上降低晚稻中重金属元素的富集效应。     

青海东部碱性土壤中硒的形态特征

以青海东部碱性富硒土壤为研究对象,通过对不同硒含量区表层土壤样的采集和分析,研究了天然富硒土壤中硒的形态特征。结果表明,研究区土壤中残渣态Se强有机态Se腐殖酸态Se水溶态Se碳酸盐态Se离子交换态Se铁锰氧化态Se;可利用态Se(即水溶态Se和离子交换态Se之和)占总Se比例为6.38%,潜在可利用态Se(即碳酸盐态Se和铁锰氧化态Se之和)占总Se比例为4.53%,这两项均高于国内部分酸性富硒土壤相应形态比例;不可利用态Se(即强有机态Se、腐殖酸结合态Se和残渣态Se之和)所占比例为89.09%,低于国内部分酸性富硒土壤中相应硒形态比例。青海碱性富硒土壤硒形态表现出高可利用态、高潜在可利用态和低不可利用态的特征。除铁锰氧化态Se外,其余6种形态均与全量Se呈显著正相关关系,而土壤总Se、腐殖酸态Se和残渣态Se与p H呈显著负相关。随着土壤碱性程度的增强,土壤总Se和不可利用态Se呈降低趋势。     

贵州省普定县耕地土壤Se分布特征

硒是重要的生命元素之一,对普定县耕地土壤硒分布特征进行研究有利于当地合理有效的开发利用富硒土地资源。本文通过对研究区3613件表层土壤样品中全硒含量进行检测分析,发现硒在土壤中的分布特征表现为明显富集于表层土,表层土壤硒含量在不同类型的土壤中的特征为:紫色土＞黄壤＞石灰土＞水稻土,而在不同成土母岩的土壤中表现为:岩浆岩＞白云岩＞碎屑岩＞灰岩;土壤硒元素主要来源于成土母岩,硒在土壤中的分布则受到土壤性质的影响,主要影响因素为pH值、土壤有机质及土壤磷的含量;本文调查发现研究区富硒(0430 mg/kg)耕地面积为4574万亩,占全县耕地总面积的7505%。     

Unity of the national and the international in the socio-cultural development of the peoples of the USSR

International unity is becoming ever stronger in this country owing to an increasing similarity in the development of the cultural environment. This comprises the provision of all the country's republics with a sufficient number of schools, theatres, and other institutions and cultural information media in accordance with the needs of the population. An important part is played by the rise in ‘the general educational level, as well as the level of professional qualifications and skills. Among all the Soviet nations and nationalities, this rise being more rapid among formerly backward peoples. Prominent among the factors of internationalization is the progressive development of the nationalities’ cultural resources, while professional culture is being increasingly brought within the reach of the masses.The implementation of the nationalities policy promotes the all-round development of all Soviet nations and nationalities, their drawing together, the upsurge of the individual capabilities of every Soviet citizen.     

Report of the restudy of the defined global stratotype of the base of the Silurian System

The Global Stratotype Section and Point （GSSP） for the base of the Silurian System was defined in 1985. Since that time, a number of researchers have suggested that this section has serious deficiencies for use as a GSSP. As a result, in 2000, the Subcommission on Silurian Stratigraphy （SSS） proposed undertaking a formal restu@ of this GSSP, which was subsequently approved by the International Commission of Stratigraphy （ICS）. The result of this restudy was the formal proposal that the current GSSP, at 1.6 m above the base of the Birkhill Shale, at Dob＇s Linn, Scotland, should be maintained as the same locality and stratigraphic level, but the bios- tratigraphical definition of the boundary should be revised. The previously defined, basal Silurian grapto- lite zone, the Parakidograptus acuminatus Zone, should be subdivided into a lower Akidograptus ascensus Zone and a higher E acuminatus Zone. The base of the A. ascensus Zone, marked by the first appearance of A. ascensus, should be regarded as the biostratigraphic mark for the base of the Silurian. This proposal has now been formally approved by the SSS and ICS, and ratified by International Union of Geological Sciences. This is the first GSSP to undergo formal restudy and redefini- tion, and the proposal also included a recommended procedure for restudy of GSSPs.     

Deviation of the major axis of the inertia ellipsoid of the Moon from the direction toward the Earth

It is known from observations that the center of mass of the Moon does not coincide with the geometric center of its figure, and the line connecting these two centers is not aligned with the direction toward the center of the Earth, instead deviating toward the Southeast. This stationary deviation of the axis of the inertia ellipsoid of the Moon to the South of the direction toward the Earth is analyzed. A system of five linear differential equations describing the physical libration of the Moon in latitude is considered, and these equations are derived using a new vector method taking into account perturbations from the Earth and partly from the Sun. The characteristic equation of this system is obtained, and all five oscillation frequencies are found. Special attention is paid to the fifth (zero) frequency, for which the solution of the latitude libration equations are stationary and represents a previously unknown additional motion of the rotational axis of theMoon in a cone with a small opening angle. In contrast to the astronomical precession of the Earth, the rotation of the angular-velocity vector is in the positive direction (counter-clockwise), with the period T ₃ = 27.32 days. On this basis, this phenomenon has been named “quasi-precession.” This quasi-precession leads to a stationary inclination of the major axis of the inertia ellipsoid of theMoon to the South (for an observer on Earth), making it possible to explain one component of the observed deviation of the center of mass of the Moon from the direction toward the Earth. The opening angle of the quasiprecession cone is approximately 0.834″.     

The Tendencies of the Development of the Mineral-Resources Sector at the Turn of the Century

Important tendencies in development of the world mineral-resources sector at the beginning of the 21st century were an increase in production and consumption of mineral materials differentiated by types of metals and nonmetallic mineral raw materials, by countries and regions, as well as the concentration of the production of mineral raw materials in a small number of countries, and a reduction in industrial reserves of minerals in the world economy, even at the current stage of their extraction. These tendencies should be taken into account in working out a strategy for development of the Russian mineral raw-material base.     

Causes of the famine among the rural population of the Sahelian zone of the Sudan

Taking the example of W Sudan, an analysis of the climatic incidents leading to the two recent famine disasters is made. On this natural background, the human side is investigated. Focus is directed towards the fragile economic structure of the famine-prone population groups. An early-warning system for famine in the Sahelian Zone is proposed taking grain production and storage, livestock development and the relationship between the prices of livestock and grain as major indicators.     

东濮凹陷北部沙河街组三段中亚段沉积环境分析

东濮凹陷北部沙三中亚段广泛发育盐岩和烃源岩,这两个看似不能共存的物质却在这里互层共生。该时期研究区沉积特征为多盐韵律与多层烃源岩互层共生、连续沉积,单个盐韵律厚度从几米到十几米,烃源岩有机质丰度高、类型好。平面上,两者在湖盆沉积沉降中心共生;垂向上,高有机质丰度、好干酪根类型与高盐度地层具有较好的对应关系。因而成为恢复古气候和古环境的重要研究对象。通过岩石学、古生物学以及Sr/Ba、B/Ga、(V+Ni+Mn)、Fe/Mn、Sr/Cu、Mg/Ca、V/(V+Ni)、稀土元素含量和氯同位素等方法对凹陷北部沙三中亚段的沉积环境进行研究。结果表明,凹陷北部沙三中亚段为深水沉积的还原环境,古盐度较高,达到半咸水-咸水沉积;微量元素和孢粉化石特征表明研究区沙三中亚段为温暖潮湿的环境。     

郯庐断裂南段研究进展与断裂性质讨论

据1：5万区域地质调查和专题研究资料，就郯庐断裂带是否南延与消失的原因，其与大别—苏鲁造山带交截形成的假位错效应，以及与中新生代沉积盆地形成演化的关系等作了新的阐述。在此基础上，讨论了郯庐断裂带是否为巨大的左行平移断层或转换断层。认为郯庐断裂带可能是在“古郯庐带”的基础上于早侏罗世重新活动、白垩纪强烈活动的地堑型枢纽断裂带。     

The Importance of the Precipitation and the Susceptibility of the Slopes for the Triggering of Landslides Along the Roads

In order to characterise the influence of the heavyrains on the observed landslides during the 1996–1997hydrological cycle, rainfall records for the last 100years are analysed from 104 stations in easternAndalusia. Regarding the amounts of rain recordedbetween October 1996 and March 1997 in the 104stations studied, 31 presented new all-time records;15 presented values that were 80–100% of thepre-1995 record; 49 stations, 80–50%; and 9stations, < 50%. A map has been devised of thesusceptibility of the materials through which thesouth-eastern Andalusian road network crosses,together with an inventory of the damage caused byinstability phenomena on banks and cuttings of theroad network during the winter of 1996–1997. Therelationships between the rainfall during the studyperiod, the damage caused to the road network and thesusceptibility of the materials affected are analysed.The results indicate that there is a clearcorrespondence between the rainfall recorded and thesusceptibility of the materials with the inventorieddamage. It is concluded that the widespread seriousdamage caused in early 1997 to the roads andsurrounding areas in the Alpujarra region and thecoast of the Province of Granada was mainly caused bythe extraordinarily heavy rains. However, considerablyless damage was observed where the susceptibility ofthe terrain is low, thus highlighting the extremeusefulness of terrain-susceptibility maps for riskprevention and territorial planning.