浙北嘉善地区土壤硒的含量、分布及其影响因素初探

基于嘉善县基本农田质量调查和嘉善县富硒土地资源专项调查中高密度的土壤硒数据及其他测试指标,对浙北嘉善表层土壤硒的含量、分布及影响因素进行了初步研究。分析结果显示,嘉善土壤总量硒平均值为0.33 mg/kg,在干窑—姚庄一带存在约57 km2的富硒土壤[w(Se)≥0.40 mg/kg];不同土属硒质量分数差别不大;硒在土壤剖面中分布的总趋势是硒在表土层聚集;嘉善富硒土壤以有机结合态和腐殖酸态两种形态为主,残渣态也占有一定比例。结合全量硒与有机碳的相关性分析和富硒土壤的硒形态分析等结果,认为高硒背景与有机质吸附对嘉善富硒土壤的形成起到了关键作用,改变了嘉善缺硒的认识。     

焉耆县北大渠乡土壤硒含量特征及影响因素研究

通过对焉耆县北大渠乡表层土壤和特色农作物全硒含量测定,分析了研究区表层土壤全硒含量特征及农作物硒含量影响因素.结果表明:表层土壤硒元素含量0.07～1.5 mg/kg,平均0.43 mg/kg,富硒土壤面积105.7 km2,占比88.07％;土壤硒主要以强有机态形式存在,被农作物有效吸收的离子交换态和水溶态硒含量仅占...     

武汉市侏儒-消泗地区农田系统中硒的分布特征及有效性研究

基于武汉市西南郊蔡甸区2个乡镇土地质量地球化学的调查分析结果,系统总结了区内土壤硒的分布特征,并探讨了有效态硒的影响因素以及硒的生物有效性。研究结果表明,区内土壤表层总量硒平均值为0.379mg/kg,背景值为0.355mg/kg,高于全国背景值,存在富硒地块面积约71.24km2,占调查区总面积的25.30%;土壤有效态硒受土壤全硒、有机碳、CEC、土壤pH值等环境因素的控制;不同农作物的富硒水平不同且与土壤背景值具有一定的相关性。这些研究结果为当地的富硒土壤资源开发利用提供了理论上的支撑。     

浙江典型富硒区硒与重金属的形态分析

通过对浙江西部龙游地区富硒土壤中Hg、Cd、Pb、As等重金属含量的研究表明,成土母岩中与硒伴生的重金属含量较高,由于特殊的地形地貌、母岩风化物质搬运条件以及有利的土壤理化性质等,土壤中重金属大为减少。异常地段重金属形态分析结果表明:土壤中仅有Cd的全量、离子交换态、碳酸盐结合态和弱有机态较高,分别为0.6mg/kg、22.1%、26.5%、11.4%;Se全量平均为0.89 mg/kg,离子交换态、弱有机态含量分别为1.12%、26.4%,碳酸盐结合态仅为0.62%。尽管如此,区内莲子、稻米等农产品仍表现出高硒低重金属等特点,居民健康长寿,发硒含量高,从而为龙游县开发富硒农产品提供了有利条件。     

安徽怀宁县富硒土壤分布、成因及硒元素水稻有效性浅析

通过对怀宁县土壤硒含量的调查和研究,发现怀宁县富硒土壤主要分布在研究区中东部石镜、黄墩、清河至黄龙一带,南部腊树及雷埠乡以及研究区北部见有零星分布。表层土壤硒含量为0.053～40.802 mg/kg,平均值为0.363 mg/kg。不同成土母质发育的土壤硒含量差异较大,二叠系至三叠系灰岩类母质发育的土壤硒含量最高,达1.146 mg/kg。相关研究表明：硒的活性与氧化还原状态有关。硒的氧化还原状况能直接影响硒的价态变化,从而影响硒的生物可利用性。     

广西金秀县头排——桐木地区富硒土壤地球化学特征及生态效应研究

基于广西金秀县头排—桐木地区土地质量地球化学调查数据资料,研究了表层土壤中硒含量的分布特征、受控因素、富硒农产品产出情况。研究表明:该地区土壤硒平均含量为0.6mg/kg,土壤硒含量0.4mg/kg的富硒土壤面积占研究区的72.8%;土壤硒含量受成土母质、土壤pH值、有机质等土壤性质的影响;农产品水稻、玉米和花生富硒率较高,水稻硒含量与根系土中全硒、pH值、有机碳以及铁含量呈正相关关系,说明这些指标对土壤-农作物系统中硒元素的地球化学行为具有明显的影响。     

安徽石台仙寓地区土壤硒地球化学特征及生物效应

为探讨安徽石台仙寓地区土壤-作物系统中硒的富集及迁移特征,在该区系统采集了岩石、土壤、灌溉水、农作物及根系土样品,研究土壤硒的地球化学特征、赋存状态、主要影响因素及生物有效性等。结果显示:研究区表层土壤硒含量为0.27~15.79 mg/kg,平均值为0.87 mg/kg,显著高于安徽省土壤背景值;土壤硒含量与有机质呈显著正相关,但与pH值无相关性;不同基岩地层的硒含量差异显著,其中蓝田组、荷塘组及皮园村组碳质页岩是该区土壤硒的主要物质来源;土壤硒形态主要为腐殖酸结合态、强有机结合态和残渣态,生物可直接利用形态的硒约占3％。研究区稻谷、茶叶对硒的平均富集系数分别为0.21和0.08,采集的水稻样品全部达到富硒标准,具有良好的富硒产业开发优势。     

贵州省桐梓县表层土壤硒地球化学特征及影响因素分析

通过贵州省桐梓县1∶5万土地质量地球化学调查评价工作,查明了境内耕地与园地表层土壤中硒的地球化学分布特征,探讨了影响表层土壤硒含量高低的因素,发现了富硒水稻与方竹笋。结果表明,全区耕地与园地表层土壤硒含量在0.02～6.59 mg/kg之间,平均值为0.58 mg/kg,二叠系龙潭组发育的土壤中硒含量最高,平均值在1.10～1.18 mg/kg之间,侏罗系发育的土壤中硒含量最低,平均值在0.22～0.32 mg/kg之间,其余地层发育的土壤硒平均值在0.42～0.70 mg/kg之间。表层土壤整体上属于富硒土壤,富硒面积70 535.52公顷,占总评价面积的70.92%,富硒资源丰富。富硒方竹笋硒含量在0.010～0.050 mg/kg之间,富硒率17.4%;富硒水稻硒含量在0.043～0.050 mg/kg之间,富硒率13.5%,水稻平均生物富集系数大于方竹笋。土壤硒含量高低主要受成土母质影响,土壤理化性质、全氮、全磷、铁锰氧化物、地形地貌与海拔高度等也是影响土壤表层土壤硒富集的重要因素。     

四川省泸州市页岩和碳酸盐岩区水稻根系土Se含量和生物有效性的控制因素

以四川省泸州市碳酸盐岩和页岩分布区为研究区,开展了Se在成土母岩-根系土-水稻籽实体系中含量特征及迁移规律研究,丰富Se元素迁移转化理论,支撑服务富硒土地开发利用。研究结果表明,研究区页岩、根系土和水稻籽实Se含量分别为0.03~1.97 mg/kg、0.27~2.38 mg/kg和0.02~0.16 mg/kg,土壤硒以有机结合态（73%）和残渣态（25%）为主,有效态硒仅占0.69%。碳酸盐岩、根系土和水稻籽实Se含量分别为0.02~0.12 mg/kg、0.21~1.33 mg/kg和0.02~0.12 mg/kg,明显低于页岩区,土壤中有机结合态和残渣态硒所占比例高达97%,有效硒比例（1.58%）高于页岩区土壤。成土母岩的矿物组成和化学成分、Se含量及赋存形式对土壤性质和Se含量具有一定的控制作用。有机质、粘土矿物和pH值是土壤Se含量和生物有效性的主要控制因素。有机质和粘土矿物对硒的强烈吸附作用是研究区土壤富硒但生物有效性低的主要原因;pH值降低导致土壤胶体对硒的吸附能力升高,使土壤Se含量升高,但硒生物有效性随pH值降低明显降低。综上所述,研究区土壤Se含量高但生物有效性低,因此水稻籽实Se含量并不高,富硒土地的开发利用不能仅以土壤全Se含量作为判别标准,应结合土壤性质及硒生物有效性综合考虑。     

北京大清河流域生态涵养区富硒土壤资源分布特征和来源解析

北京是典型的硒缺乏地理分布区,但近些年研究成果表明局部地区土壤达到富硒水平,掌握该区富硒分布特征对于开展北京地区的富硒环境研究和开发利用富硒土地资源具有重要意义。本文以北京大清河流域生态涵养区1615km~2地球化学调查数据为基础,采用原子荧光光谱(AFS)等方法测定了研究区1297件表层土壤、25组玉米及对应根系土壤和15件岩石中Se等地球化学指标;利用相关分析、多元统计分析方法,结合GIS技术,研究土壤和农作物中硒含量特征、富硒成因来源以及土壤硒与碳铁磷等其他元素的关系,评价富硒土地的安全性。结果表明:研究区土壤硒含量区间为0.055～0.465mg/kg,背景值为0.257mg/kg,呈现富硒特征,厘定出360.4km~2富硒土地资源。当地种植的玉米硒含量变化范围为0.028～0.70mg/kg,几何均值为0.20mg/kg,80%的玉米样本为富硒农产品,且土壤富硒与作物富硒空间分布一致,指示土壤硒是作物体内硒的重要供给来源。研究认为,地质背景和成土母质是研究区富硒土地资源分布的主控因素,河流相沉积的暗色岩系是重要的土壤硒来源。富硒土地整体环境质量清洁安全,仅3.23km~2(面积占比0.2%)土壤重金属(镉汞铅)含量超风险管控值,在土地开发过程中需重点关注。     

The terrestrial fauna of the Late Triassic Pant-y-ffynnon Quarry fissures,South Wales,UK and a new species of Clevosaurus (Lepidosauria: Rhynchocephalia)

Pant-y-ffynnon Quarry in South Wales yielded a rich cache of fossils in the early 1950s, including articulated specimens of new species (the small sauropodomorph dinosaur Pantydraco caducus and the crocodylomorph Terrestrisuchus gracilis), but no substantial study of the wider fauna of the Pant-y-ffynnon fissure systems has been published. Here, our overview of existing specimens, a few described but mostly undescribed, as well as freshly processed material, provides a comprehensive picture of the Pant-y-ffynnon palaeo-island of the Late Triassic. This was an island with a relatively impoverished fauna dominated by small clevosaurs (rhynchocephalians), including a new species, Clevosaurus cambrica, described here from a partially articulated specimen and isolated bones. The new species has a dental morphology that is intermediate between the Late Triassic Clevosaurus hudsoni, from Cromhall Quarry to the east, and the younger C. convallis from Pant Quarry to the west, suggesting adaptive radiation of clevosaurs in the palaeo-archipelago. The larger reptiles on the palaeo-island do not exceed 1.5?m in length, including a small carnivorous crocodylomorph, Terrestrisuchus, and a possible example of insular dwarfism in the basal dinosaur Pantydraco.     

The effect of water on accessory phase solubility in subaluminous and peralkaline granitic melts

The solubilities of columbite, tantalite, wolframite, rutile, zircon and hafnon were determined as a function of the water contents in peralkaline and subaluminous granite melts. All experiments were conducted at 1035 °C and 2 kbar and the water contents of the melts ranged from nominally dry to approximately 6 wt.% H₂O. Accessory phase solubilities are not affected by the water content of the peralkaline melt. By contrast, solubilities are affected by the water content of the subaluminous melt, where the solubilities of all the accessory phases examined increase with the water content of the melt, up to 2 wt.% H₂O. At higher water contents, solubilities are nearly constant. It can be concluded that water is not an important control of accessory phase solubility, although the water content will affect diffusivities of components in the melt, thus whether or not accessory phases will be present as restite material. The solubility behaviour in the subaluminous and peralkaline melts supports previous spectroscopic studies, which have observed differences in the coordination of high field strength elements in dry vs. wet subaluminous granitic glasses, but not for peralkaline granitic glasses. Lastly, the fact that wolframite solubility increases with increasing water content in the subaluminous melt suggests that tungsten dissolved as a hexavalent species.     

Quaternary stresses revealed by calcite twinning inversion: insights from observations in the Savonnières underground quarry (eastern France)

Calcite samples were extracted both from the rock matrix and the superficial coating of a karstified fault plane of an underground quarry, located in the eastern border of the Paris basin. The karstification is dated as Quaternary. Analysis of mechanical calcite twinning reveals that only the calcite matrix has also undergone a compression trending WNW that can be attributed to the Mio-Pliocene alpine collision. Both coating and matrix have undergone a strike-slip regime with σ₁ roughly trending north–south, that could correspond to the regional present-day state of stress, a strike-slip compression rather trending NNW, modified by local phenomena. To cite this article: M. Rocher et al., C. R. Geoscience 335 (2003).     

HYDROGEOLOGY

正20141756 Chen Ruige(Mathematical College,China University of Geosciences,Beijing100083,China);Zhou Xun Numerical Simulation of Groundwater Level Fluctuation in a Coastal Confined Aquifer with Sloping Initial Groundwater Level Induced by the Tide(Geological Bulletin of China,ISSN1671-2552,CN11-4648/P,32(7),2013,p.1099-1104,6 illus.,16 refs.) Key words:confined water,groundwater level     

METAMORPHIC PETROLOGY

正20141408 Cai Jia(Institute of Geology,Chinese Academy of Geological Sciences,Beijing100037,China);Liu Fulai Petrogenesis and Metamorphic P-T Conditions of Garnet-Spinel-Biotitebearing Paragneiss in Danangou Area,Daqingshan-Wulashan Metamorphic Complex Belt(Acta Petrologica Sinica,ISSN1000-0569,CN11-1922/P,29(7),     

SERIALS

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GEOPHYSICAL EXPLORATION

正20142386An Guoying(China Aero Geophysical Survey and Remote Sensing Center for Land and Resources,Beijing 100083,China)Application of Satellite Remote Sensing in Regional Hydrogeological Investigation:Taking Cenozoic Strata in Wenquan Sheet(1∶250 000)of Karakoram Range as an Example(Geosci-     

QUATERNARY GEOLOGY & GEOMORPHOLOGY

正20141016An Chengbang(Key Laboratory of Western China’s Environmental Systems,Ministry of Education,Lanzhou University,Lanzhou 730000,China);Zhao Yongtao Lake Records during the Last Glacial Maximum from Xinjiang,NW China and Their Climatic Impli-     

PETROLEUM GEOLOGY

正20141538 Cao Qing(School of Earth Sciences and Engineering,Xi’an Petroleum University,Xi’an 710065,China);Zhao Jingzhou Characteristics and Significance of Fluid Inclusions from Majiagou Formation,Yichuan Huangling Area,Ordos Basin(Advances in Earth Science,ISSN1001-8166,CN62-1091/P,28(7),2013,p.819-828,7 illus.,3 tables,43 refs.)     

GEOCHEMISTRY

正20142002 Wei Hualing(Institute of Geophysical and Geochemical Exploration,Chinese Academy of Geological Sciences,Langfang065000,China);Zhou Guohua Element Content and Mineral Compositions in Different Sizes of Soil in Tongling Area,Anhui Province(Geological Bulletin of China,ISSN1671-2552,CN11-4648/P,32(11),2013,p.1861