Nucleosynthesis and Mixing in Cassiopeia A

We present results from the first light observations of the Cassiopeia A supernova remnant (SNR) by the Chandra X-Ray Observatory. Based on representative spectra from four selected regions, we investigate the processes of nucleosynthesis and mixing in Cas A. We make the first unequivocal identification of iron-rich ejecta produced by explosive silicon burning in a young Galactic SNR. Elsewhere in the remnant, we see silicon-rich ejecta from explosive oxygen burning. The Fe-rich ejecta lie outside the Si-rich material, indicating that bulk motions were extensive and energetic enough in Cas A to cause a spatial inversion of a significant portion of the supernova core. It is likely that this inversion was caused by "Fe"-rich ejecta emerging in plumes from the rising bubbles in the neutrino-driven convection layer during the supernova explosion. In addition, the radioactive decay energy from 56Ni may have contributed to the subsequent evolution of the material. We have also discovered faint, well-defined filaments with featureless X-ray spectra that are possibly sites of cosmic-ray acceleration in Cas A.     

长垣县城区冬季噪声监测与评价

借助HS6288系列噪声分析仪,对河南省长垣县城区噪声进行了实地监测。依据国家城市区域环境噪声标准,并结合综合污染指数法和模糊综合评价法对监测结果进行分析评价。结果表明,长垣县城区总体噪声水平为4级(中污染),声环境已出现恶化。在分析长垣县城区噪声污染及其分布的同时,结合实地调查,提出了一些针对小城镇噪声污染防治的对策。     

巴布亚新几内亚波尔盖拉（Porgera）金矿床流体化学及其作用

巴布亚新几内亚波尔盖拉（Ｐｏｒｇｅｒａ）金矿床是世界的碱性浅成熟液金矿体系（第Ⅱ阶段）的一个实例,同时它经过岩浆热液金成矿的初始阶段（第Ⅰ阶段）,通过这两个成矿阶段矿脉中流体包囊体的气体及离子色谱分析（ＧＣ和ＩＣ）可确定在成矿过程中流体的组分及其参与过程。这些数据资料显示了三种端元组分流体的存在,其中最稀释的一种贯穿了整个成矿过程,被认为是大气起源经过演化的地下水,它的成分包括５００ｍｉＭＮａ＾＋     

《海洋地质与第四纪地质》论文作者群的统计与分析

《海洋地质与第四纪地质》是原地质矿产部海洋地质研究所和地质矿产部第四纪地质研究中心主办的综合性学术期刊，创刊于１９８１年，在国内外地学界具有较高的知名度。对该刊论文作者进行统计分析，有助于了解我国海洋地质科研队伍的现状及发展历史。１《海洋地质与第四纪...     

我国科技期刊被引用情况的分析--以《海洋地质与第四纪地质》为例

科技期刊是反映科学技术产出水平的窗口,其期刊和论 文被国际著名检索系统收录的多少是衡量一个国家科技水 平高低的重要标志之一.众所周知,世界重要检索系统有美 国的<科学引文索引>(SCI)、<工程索引>(EI)、<化学文摘> (CA),英国的<科学文摘>(SA),前苏联的<文摘杂志>(PЖ) 和日本的<科学技术文献速报>(CBST),即6大检索系统.但 最有影响力的引文索引类期刊(或光盘)是美国科学情报研 究所(ISI)编辑出版的、美国的以及美国的<科学 技术会议录>(ISTP).主要收选国际范围内期刊的数、 理、化、农、林、医及生物学等科技文献,对工程技术文献报道 比重较小,故普遍认为收录的科技论文反映的是基础 科学研究水平;是美国工程索引公司编制的大型综合类 工程技术文献检索刊物,主要涉及工程和应用技术学科; 也是由美国科学情报所编辑出版,它摘录的会议文 献往往代表一门学科或专业领域的最新成果,反映了世界上 科学技术发展的水平和趋势.中国科技信息研究所自1987 年出版的<中国科技论文统计与分析>(年度研究报告)同样 也将这3个检索系统作为重要的数据统计源,为期刊的学术 水平评价建立了引文数据库,并且从1996年开始编辑出版 了<中国科技期刊引证报告>,对期刊的引文情况及其评价设 立了多项指标,这为广大科技工作者、科研管理部门科学地 评价、选择和利用期刊,尤其是为期刊编辑部客观地评价自 己的刊物在科学活动和文献交流中所处的地位、所起的作用 及其质量优劣均提供了可靠的依据和标准.     

Organochlorines and dioxin-like compounds in green-lipped mussels Perna viridis from Hong Kong mariculture zones

Concentrations of persistent organic pollutants including polychlorinated biphenyls (PCBs), organochlorine (OC) pesticides and dioxin-like compounds were measured in green-lipped mussels, Perna viridis, collected from seven mariculture zones in Hong Kong between September and October in 2002 in order to evaluate the status, spatial distribution and potential sources of pollution in these areas. Concentrations ranged from 300 to 4400 ng/g lipid weight for total OCs and 170–1000 ng/g lipid weight for total PCBs (based on 28 congeners). Relatively smaller DDT concentrations in mussels compared with previous studies suggest reduced discharges of DDTs from nearby regions into Hong Kong waters. Detection of a mixture of HCH isomers in the mussels indicated that Hong Kong waters were predominantly contaminated by technical HCHs rather than lindane. Mussel samples from all sampling locations elicited significant dioxin-like activity in the H4IIE-luc bioassay. The greatest magnitude of dioxin-like response (39 pg TEQ/g wet wt.) was detected in mussels from Ma Wan in the western waters of Hong Kong, which is strongly influenced by the Pearl River discharge. Human health risk assessment was undertaken to evaluate potential risks associated with the consumption of the green-lipped mussels. Risk quotient (RQ) for dioxin-like compounds was greater than unity suggesting that adverse health effects may be associated with high mussel consumption.     

A review of pollutants in the sea-surface microlayer (SML): a unique habitat for marine organisms

Boundary layers between different environmental compartments represent critical interfaces for biological, chemical and physical processes. The sea-surface microlayer (uppermost 1-1000 microm layer) forms the boundary layer interface between the atmosphere and ocean. Environmental processes are controlled by the SML, and it is known to play a key role in the global distribution of anthropogenic pollutants. Due to its unique chemical composition, the upper organic film of the SML represents both a sink and a source for a range of pollutants including chlorinated hydrocarbons, organotin compounds, petroleum hydrocarbons, polycyclic aromatic hydrocarbons (PAH) and heavy metals. These pollutants can be enriched in the SML by up to 500 times relative to concentrations occurring in the underlying bulk water column. The SML is also a unique ecosystem, serving as an important habitat for fish eggs and larvae. Concentration ranges and enrichment factors of pollutants in the SML in different areas of the world's oceans have been critically reviewed, together with available toxicity data for marine biota found within the SML. Overall, the SML is highly contaminated in many urban and industrialized areas of the world, resulting in severe ecotoxicological impacts. Such impacts may lead to drastic effects on the marine food web and to fishery recruitment in coastal waters. Studies of the toxicity of fish eggs and larvae exposed to the SML contaminants have shown that the SML in polluted areas leads to significantly higher rates of mortality and abnormality of fish embryos and larvae.