Impact of sediment organic matter quality on the fate and effects of fluoranthene in the infaunal brittle star Amphiura filiformis

Hydrophobic contaminants, such as polycyclic aromatic hydrocarbons (PAHs) readily adsorb to organic matter. The aim of this study was to determine the importance of the quality of sedimentary organic matter for the uptake, biotransformation and toxicity of the PAH, fluoranthene (Flu), in the infaunal brittle star Amphiura filiformis. Brittle stars were exposed to a base sediment covered by a 2 cm Flu-spiked top layer (30 microg Flu/g dry wt. sed.), enriched to the same total organic carbon content with either refractory or labile organic matter. The labile carbon source was concentrated green flagellate: Tetraselmis spp. The refractory carbon source was lignin from a paper mill. Tissue concentrations of Flu both in disk and arm-fractions were determined as total Flu, parent Flu (i.e. untransformed), aqueous Flu-metabolites, polar Flu-metabolites and tissue residue Flu (i.e. unextractable). Our results showed that sediment particle ingestion is a pathway by which Flu can enter benthic food webs. Flu toxicity (measured as arm-regeneration), but not net accumulation, was dependent on the nutritional quality of the ingested sediment particles. Flu bioaccumulation could not be attributed solely to equilibrium partitioning between organism lipid content and organic content of the sediment. Biotransformation of Flu by brittle stars was very limited and unaffected by organic matter quality. A. filiformis contributed to the downward transport of Flu from the surface sediment to the burrow lining. The limited breakdown of parent Flu by brittle stars and/or microorganisms was relatively higher in burrows compared to surface sediment, and highest in the presence of labile organic matter. Tissue concentrations were higher in disk than in arms, but the proportion of metabolic products relative to parent Flu was higher in arms than in the disk fraction. We estimate that the yearly mobilization of sediment-associated Flu by arm-regeneration in A. filiformis is in the range of 3.8-29.4 microg total Flu eq. m(-2) year(-1) at a sediment concentration of 30 microg Flu/g dry wt. sed.     

气候转型与早期人类迁徙

目前的旧石器考古证据表明，更新世早期可能发生了两次人类迁徙浪潮，时间分别在1.8-1.6MaBP和1.0MaBP左右，第一阶段，古人类演化为直立人并开始走出非洲、迁徙至其它中低纬度的热带－亚热带地区；第二阶段，直立人开始占据中高纬度的温带和干旱－半干旱地区。这两个阶段也是第四纪气候发生转型、环境产生重大调整的时期。二者在发生时间上的一致性揭示了它们之间的内在联系，推测气候转型时期环境转变是这两次人类迁徙浪潮的主要驱动力。     

青藏高原研究进入最佳期和青年肩负的责任

这是中国青藏高原研究会理事长刘东生院士在该会青藏高原青年科技奖第一次颁奖大会(1996年3月6日)上的演讲。本文指出了当前青藏高原研究的方向,表达了对青年一代的殷切期望。征得作者同意,以飨读者。青藏高原青年科技奖获奖者是:丁林、王保海、方小敏、刘晓东、刘燕华、张春光、高锐、姚檀栋、彭敏、廖俊国。     

我国地方性氟病的地球化学问题

Endemic fluorine disease is a chronic fluorine poisoning caused by high level of fluorine in drinking water or foods. Incidence of this disease has been knowu in many parts of the world. In China its occurrence has been observed in the Northeast, Northwest, Southwest and some other localities. Investigation shows that it is closely related to geochemical environment: Major fluorine sources in nature include fluorinerich volcanic rocks, calcareous dolomites, phosphorus-bearing rocks/loess and Quarternary loose sediments. Under special conditions fluorine is concentrated in ground water or soil and seeks its way into human body through diet. Areas With high fluorine concentration responsible for the fluorine disease can be classified into four types, depending on characteristics of geochemical environment: (1) Arid and semiarid calcium-rich soda saline areas; (2) Semiarid, alternatively marine-terrestrial strata with a high degree of salinity; (3) Semihumid iron- and aluminum-rich intermediate-acid soils; (4) Localities where fluorine-rich rocks or deposits are developed;and those with high fluorine content as a result of industrial pollution. Based on medical statistics and chemical analyses, of water, soil, food and other related samplcs,this work will provide a scientific baekground for the prevention and control of fluorine disease.     

泥河湾与黄土高原地层对比及其旧石器文化序列

泥河湾盆地和黄土高原堆积着我国第四纪划分和对比的标准地层，同时也是古人类活动的重要场所。两者沉积环境不同，但都较为连续地记录了中国北方第四纪气候环境演化历史和古人类活动的信息。在综合前人研究成果的基础上，对这两个重要地区的地层进行了对比，并列出了两个地区的旧石器文化地层序列。     

缅怀中国孢粉学和古植物演化学的奠基人徐仁院士

徐仁院士 ( 1 91 0～ 1 992 )逝世已经 1 0年 ,但他的音容笑貌至今依然时时回荡在我们的思绪之中 ;他传授给我们的学识仍继续贯穿在我们的工作中 ,并将代代相传。徐先生是中国孢粉学和古植物演化学的先驱者和奠基人。他在 1 952年自印度回国之后 ,即持续不断地在南京和北京开展孢粉学和古植物学研究并分别建立了实验室 ,培养了不止一代的孢粉学家、古植物学家和许多学术带头人。有这样一批生力军 ,经过 4 0多年的不断努力 ,才使得我国这一学科能够发展到今天这样的规模和水平。徐先生不愧是中国孢粉学和植物演化学上建功立业的功臣 ,深为人…     

雷州半岛全新世高温期珊瑚生长所揭示的环境突变事件

通过对南海北部雷州半岛徐闻县灯楼角角孔珊瑚礁剖面(20°14.005′N, 109°55.200′E)的研究, 发现在全新世高温期存在至少9次高频率、大幅度的气候突然变冷事件, 将这一现象命名为“雷州事件”. 这一时期是雷州半岛珊瑚礁发育的适宜期, 至少可分为9个阶段, 每一阶段(即一次气候适宜期)的持续时间约20~50 a, 之后即在冬季突然出现一次低温和(或)相对低海平面事件, 导致角孔珊瑚大量死亡, 并出露遭受磨蚀, 形成间断面; 如此循环往复, 形成厚逾4 m的角孔珊瑚礁坪. 此段时间地壳分阶段性地下沉, 海平面上升. 该珊瑚礁剖面是研究中国南部热带地区全新世高温期年代际气候变化的宝贵的材料, 为全新世高温期的高频气候不稳定性演化模式提供了新的证据, 对传统的全新世大暖期的气候特征提供了新的认识.     

Counting chronology and climate records with about 1000 annual layers of a Holocene stalagmite from the Water Cave in Liaoning Province, China

One active stalagmite from the Water Cave in Liaoning Province contains growth layers of three sizes. Based on thermal ionization mass spectrometry 230Th dating, we found that middle size layers are annual layers, with each middle layer consisting of one narrow dark layer and a wide bright layer. The small layers within middle layers are sub-annual layers and the large layers are multi-year layers. Based on the layer-counting method, we established a high-resolution time scale for layer thickness. Our results reveal two dramatic century-scale climate cycles over the past 1000 years in this region.     

两个冰期-间冰期旋回的黄土记录及其古气候意义

北京邻区枣沟、斋堂和赤峰黄土－古土壤剖面粒度和磁化率变化在幅度和相位上都有明显的差异。在两个冰期－间冰期旋回，磁化率记录具有冰量变化模式，而粒度记录具有轨道周期特点，粒度和磁化率之间的相位关系在从冰期向间冰期转换和冰期向间冰期过渡的过程中，既有滞后也有超前的表现，很难单纯以成土作用来解释。由于黄土粒度主要反映粉尘源区环境和古风场强度的变化，而磁化率主要记录的是沉积区的成壤作用，反映夏季风的强度变化，因此剖面粒度和磁化率变化的不协调说明古风场和粉尘源区变化与粉尘沉积区气候变化之间不统一。这可能意味着控制夏季风强度变化和控制冬季风强度变化的机制存在差异。