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101.
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The major elements, rare earth elements (REE) and trace elements of four basalt samples from central and western Pacific ferro- manganese crust provinces have been analyzed using chemical methods and ICP - MS, respectively. The results indicate that the samples have been extensively altered and that the contents of their major elements have changed significantly. However, the similarity of REE partition patterns and trace element contents of basalt samples to those of fresh oceanic island basalts (OIB) indicate that the basalt samples originated as OIB. Because of low-temperature alteration, the contents of A1203 , Fe203 , MnO, K20 and P205 increased, while MgO and FeO decreased. Active components, such as magnesium and iron, were leached from OIB resulting in the relative enrichment of SiO2. The leaching of active components can cause the relative enrichment of REE, while the precipitation of LREE-rich ferromanganese oxides in vesicles and fissures not only causes an increase of REE contents, but also induces "fractionation" of LREE and HREE. Based on the enrichment mechanism of REE contents, the theoretical quantities of precipitated ferromanganese oxides and the depleted quantities of active components are calculated : the depleted quantities of active components for the unit mass of fresh basalts vary in the range of 0.15 ~ 0. 657, and the precipitated quantities of ferromanganese oxides for the unit mass of fresh basahs vary in the range of 0. 006 ~ 0. 042. Of the major elements, the two most depleted are iron, and magnesium, with 18.28% ~ 70.95% of iron and 44.50% ~ 93.94% of magnesium in the fresh basalts was leached out. Theoretical calculation and geochemistry results both indicate that low-temperature alteration of basalts can supply abundant amount of metals to seawater, and may play an important role in ocean metal circulation. 相似文献
103.
稀土元素Ce对雨生红球藻生长及虾青素积累影响的研究 总被引:2,自引:0,他引:2
采用反相高效液相色谱分析法(RP-HPLC)研究了稀土元素铈(Ce^3+)对雨生红球藻(Haematococcus pluvialis)生长及虾青素积累的影响。结果表明,低质量浓度的Ce^3+对微藻生长和虾青素积累均具有明显的促进作用,当Ce^3+的质量浓度为0.1mgm时,对藻生长的促进效果最佳,细胞密度较对照组提高34%;当Ce^3+的质量浓度为1mg/L时,虾青素质量分数可达到细胞干质量的3.2%,较对照组提高167%。此外,高质量浓度Ce^3+的对雨生红球藻有抑制作用,当Ce^3+的质量浓度高于40mgm时,红球藻的生长完全被抑制,虾青素质量分数也明显降低。 相似文献
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By tracking and monitoring the profile configuration, topography, and hydrodynamic factors of an artificial cobble beach in Tianquan Bay, Xiamen, China over three consecutive years after its completion, we analyzed the evolution of its profile configuration and plane morphology, and its storm response characteristics. The evolution of the profile configuration of the artificial cobble beach in Tianquan Bay can be divided into four stages. The beach was unstable during the initial stage after the beach nourishment the profile configuration changed obviously, and an upper concave composite cobble beach formed gradually, which was characterized by a steep upper part and a gentle lower part. In the second stage, the cobble beach approached dynamic equilibrium with minor changes in the profile configuration. At the third stage the beach was in a high-energy state under the influence of Typhoon Meranti, and the response of the artificial cobble beach differed significantly from that of the low-tide terrace sandy beach. Within a short time, there was net onshore transport of cobbles in the cross-shore direction. The beach face was eroded, the beach berm was accumulated, and the slope of the beach was steepened considerably. In the alongshore direction, there was notable transport of cobbles on the beach from east to west along the shore, and the total volume of the beach decreased by 4.5×103 m~3, which accounted for 50% of the total amount of beach volume lost within three years. The fourth stage was the restoration stage after the typhoon, characterized by a little gentler profile slope and the increase in width and the decrease in height of beach berm. Because of the action of waves and the wave-driven longshore current caused by the specific terrain and landform conditions along the coast(e.g., coastal headlands, near-shore artificial structures, and reefs), the coastline of the artificial cobble beach gradually evolved from being essentially parallel to the artificial coast upon completion to a slightly curved parabolic shape, and three distinct erosion hotspots were formed on the west side of the cape and the artificial drainpipe, and the reefs. Generally, the adoption of cobbles for beach nourishment on this macro-tidal coast beach with severe erosion has yielded excellent stability and adaptability. 相似文献
108.
潜流带(即地表水-地下水交互作用带)是位于地表水和地下水之间发生物质和能量交换的,具有物理、化学、生物梯度的饱和含水带。潜流带内发生着强烈的生物地球化学过程,在改善水环境质量和维持水生态系统稳定中发挥着重要作用。潜流带生物地球化学特征主要受河床沉积物结构特征、水文特征、环境特征、生物群落格局、物质输入等因素的影响,潜流带内C、N、P元素以及有毒金属元素(Fe、Mn、As、Hg等)会发生氧化-还原、吸附与解吸、沉淀与溶解、生物催化等生物地球化学过程。原位监测、数值模拟、原位培养和地球物理探测等技术是潜流带中生物地球化学过程研究中常用的研究手段。未来针对潜流带的研究可以从监测和数值模拟技术、河床沉积物变化特征以及微生物生态系统的结构和功能等方面进一步开展。 相似文献
109.
贫困村空间分布及影响因素分析——以乌蒙山连片特困区为例 总被引:3,自引:0,他引:3
针对目前贫困分布研究以大尺度为主而缺乏对小尺度的关注和致贫因素分析忽略个体效应或背景效应的不足,基于空间贫困视角,以乌蒙山片区为研究区域、贫困村为研究对象,运用空间点模式分析方法探究贫困村空间分布特征,并设计多层线性回归模型从贫困村和县域两个层面综合定量剖析贫困影响因素。研究发现:① 贫困村的空间聚集特征较为明显,总体分布呈现大分散小集中、散点-极核-轴带-团块并存的空间格局。② 贫困村的贫困程度受多层因素的显著影响。其中,村级影响因素为:人口密度、通路率、劳动力比例、遭受自然灾害频次、安全饮用水比例;县级影响因素为:人均地方生产总值、高中阶段毛入学率、植被覆盖率。③ 农村贫困来源于贫困村与县域的双重作用。因此在精准扶贫工作中,政府及相关部门可针对不同尺度对象有针对性地施策,合理配置扶贫资金。 相似文献
110.
为研究东海区厚壳贻贝(Mytilus coruscus)遗传多样性,以厚壳贻贝F mtDNA D-loop为标记,对浙江省舟山嵊山岛、宁波渔山岛、温州南麂岛、福建省宁德湾和莆田南日岛五个海区的厚壳贻贝群体进行了遗传分析。结果表明,厚壳贻贝各群体的遗传多样性差异不明显,在5个群体中,宁德群体的遗传多样性相对最丰富;将5个群体作为一个整体时,呈现出较高的单倍型多样性和较低的核苷酸多样性。对厚壳贻贝5个群体间的遗传分化系数(Fst)和基因流(Nm)进行检测,结果显示群体间Fst值都很低,但Nm值都很高(Nm绝对值1),表明5个群体间存在丰富的基因交流。但宁德群体与浙江沿海的3个群体(嵊山、渔山、温州)的Fst值相对较高,且差异显著(P0.5),表明宁德群体与这3个群体间出现遗传分化。本研究旨在为海洋经济贝类资源的保护管理提供理论依据。 相似文献