GEOTRACES - An international study of the global marine biogeochemical cycles of trace elements and their isotopes

Trace elements serve important roles as regulators of ocean processes including marine ecosystem dynamics and carbon cycling. The role of iron, for instance, is well known as a limiting micronutrient in the surface ocean. Several other trace elements also play crucial roles in ecosystem function and their supply therefore controls the structure, and possibly the productivity, of marine ecosystems. Understanding the biogeochemical cycling of these micronutrients requires knowledge of their diverse sources and sinks, as well as their transport and chemical form in the ocean.Much of what is known about past ocean conditions, and therefore about the processes driving global climate change, is derived from trace-element and isotope patterns recorded in marine deposits. Reading the geochemical information archived in marine sediments informs us about past changes in fundamental ocean conditions such as temperature, salinity, pH, carbon chemistry, ocean circulation and biological productivity. These records provide our principal source of information about the ocean's role in past climate change. Understanding this role offers unique insights into the future consequences of global change.The cycle of many trace elements and isotopes has been significantly impacted by human activity. Some of these are harmful to the natural and human environment due to their toxicity and/or radioactivity. Understanding the processes that control the transport and fate of these contaminants is an important aspect of protecting the ocean environment. Such understanding requires accurate knowledge of the natural biogeochemical cycling of these elements so that changes due to human activity can be put in context.Despite the recognised importance of understanding the geochemical cycles of trace elements and isotopes, limited knowledge of their sources and sinks in the ocean and the rates and mechanisms governing their internal cycling, constrains their application to illuminating the problems outlined above. Marine geochemists are poised to make significant progress in trace-element biogeochemistry. Advances in clean sampling protocols and analytical techniques provide unprecedented capability for high-density sampling and measurement of a wide range of trace elements and isotopes which can be combined with new modelling strategies that have evolved from the World Ocean Circulation Experiment (WOCE) and Joint Global Ocean Flux Study (JGOFS) programmes. A major new international research programme, GEOTRACES, has now been developed as a result of community input to study the global marine biogeochemical cycles of trace elements and their isotopes. Here, we describe this programme and its rationale.     

Nitrogen isotopic composition of macromolecular organic matter in interplanetary dust particles

Nitrogen concentrations and isotopic compositions were measured by ion microprobe scanning imaging in two interplanetary dust particles L2021 K1 and L2036 E22, in which imaging of D/H and C/H ratios has previously evidenced the presence of D-rich macromolecular organic components. High nitrogen concentrations of 10-20 wt% and δ¹⁵N values up to +400‰ are observed in these D-rich macromolecular components. The previous study of D/H and C/H ratios has revealed three different D-rich macromolecular phases. The one previously ascribed to macromolecular organic matter akin the insoluble organic matter (IOM) from carbonaceous chondrites is enriched in nitrogen by one order of magnitude compared to the carbonaceous chondrite IOM, although its isotopic composition is still similar to what is known from Renazzo (δ¹⁵N = +208‰).The correlation observed in macromolecular organic material between the D- and ¹⁵N-excesses suggests that the latter originate probably from chemical reactions typical of the cold interstellar medium. These interstellar materials preserved to some extent in IDPs are therefore macromolecular organic components with various aliphaticity and aromaticity. They are heavily N-heterosubstituted as shown by their high nitrogen concentrations >10 wt%. They have high D/H ratios >10⁻³ and δ¹⁵N values ≥ +400‰. In L2021 K1 a mixture is observed at the micron scale between interstellar and chondritic-like organic phases. This indicates that some IDPs contain organic materials processed at various heliocentric distances in a turbulent nebula. Comparison with observation in comets suggests that these molecules may be cometary macromolecules. A correlation is observed between the D/H ratios and δ¹⁵N values of macromolecular organic matter from IDPs, meteorites, the Earth and of major nebular reservoirs. This suggests that most macromolecular organic matter in the inner solar system was probably issued from interstellar precursors and further processed in the protosolar nebula.     

非静力平衡层结大气中的重力惯性波和惯性对流

本文根据一些新的流体力学实验结果及某些天气事实,建立了一个非静力平衡条件下旋转地球大气中重力惯性波和惯性对流的理论模型,并分别求出它在稳定层结,中性层结及不稳定层结三种情况下的点源扰动函数形式的解。 分析解的性质得知,中性及弱不稳定大气中可以激发一种主要由地球旋转惯性决定的大幅度垂直速度振动,其周期大于(至少等于)地球在该纬度的惯性周期2π/f。这也许能说明文献[1]所发现的那种准周期性惯性对流的某些动力性质。在稳定层结流体中,地球旋转参数对流体重力振荡的频率影响不大,层结越稳定,越类似于单纯的重力振荡,只有在层结接近中性时,f对重力振荡的频率修正作用才明显起来。 最后给出不同纬度处不稳定层结大气中所能产生的惯性对流的最大临界尺度。     

斜发沸石岩的阳离子交换性能——对钾离子选择吸附的研究

斜发沸石是天然沸石中较常见和具有实际应用价值的一种。其化学分子式为:Ca（Na·K）₄Al₆Si₃₀O₇₂·24H₂O。关于斜发沸石的吸附、阳离子交换等性能,国外已有很多研究,并已将天然的斜发沸石、丝光沸石应用于从空气中富集氧、石油化工、原子能放射性废水和工业污水的处理、干燥剂,土壤改良剂、造纸充填剂等许多方面。     

Calcium‐aluminum‐rich inclusions and amoeboid olivine aggregates from the CR carbonaceous chondrites

Abstract— Calcium‐aluminum‐rich refractory inclusions (CAIs) in CR chondrites are rare (<1 vol%), fairly small (<500 μm) and irregularly‐shaped, and most of them are fragmented. Based on the mineralogy and petrography, they can be divided into grossite ± hibonite‐rich, melilite‐rich, and pyroxene‐anorthite‐rich CAIs. Other types of refractory objects include fine‐grained spinel‐melilite‐pyroxene aggregates and amoeboid olivine aggregates (AOAs). Some of the pyroxene‐anorthite‐rich CAIs have igneous textures, and most melilite‐rich CAIs share similarities to both the fluffy and compact type A CAIs found in CV chondrites. One major difference between these CAIs and those in CV, CM, and CO chondrites is that secondary mineral phases are rare. In situ ion microprobe analyses of oxygen‐isotopic compositions of 27 CAIs and AOAs from seven CR chondrites demonstrate that most of the CAIs are ¹⁶O‐rich (δ¹⁷O of hibonite, melilite, spinel, pyroxene, and anorthite < ?22‰) and isotopically homogeneous within 3–4‰. Likewise, forsterite, spinel, anorthite, and pyroxene in AOAs have nearly identical, ¹⁶O‐rich compositions (?24‰ < δ¹⁷O < ?20‰). In contrast, objects which show petrographic evidence for extensive melting are not as ¹⁶O‐rich (δ¹⁷O less than ?18‰). Secondary alteration minerals replacing ¹⁶O‐rich melilite in melilite‐rich CAIs plot along the terrestrial fractionation line. Most CR CAIs and AOAs are mineralogically pristine objects that largely escaped thermal metamorphism and secondary alteration processes, which is reflected in their relatively homogeneous ¹⁶O‐rich compositions. It is likely that these objects (or their precursors) condensed in an ¹⁶O‐rich gaseous reservoir in the solar nebula. In contrast, several igneous CAIs are not very enriched in ¹⁶O, probably as a result of their having melted in the presence of a relatively ¹⁶O‐poor nebular gas. If the precursors of these CAIs were as ¹⁶O‐rich as other CR CAIs, this implies either temporal excursions in the isotopic composition of the gas in the CAI‐forming regions and/or radial transport of some CAI precursors into an ¹⁶O‐poor gas. The absence of oxygen isotope heterogeneity in the primary minerals of melilite‐rich CAIs containing alteration products suggests that mineralogical alteration in CR chondrites did not affect oxygen‐isotopic compositions of their CAIs.     

论江西气象综合观测体系改革与建设

介绍了江西现有的气象综合观测体系,并就江西气象综合观测体系改革与建设的内容进行了论述,认为江西气象综合观测体系的改革与建设,应按照中国气象局调整“国家气候观象台、国家气象观测站、区域气象观测站”3类台站布局,构建“国家气候监测网、国家天气观测网、国家专业气象观测网和区域气象观测网”的总体要求,坚持全面性、开放性、可行性和连续性相统一的原则,根据一站多用、一站多能和一体化、集约化的原则,结合江西经济社会发展、国家安全和可持续发展的实际需要,对全省各台站进行统筹规划、科学布局,形成一站多点、一站多能、满足多轨道业务需求的综合气象观测网。     

在线液—液萃取微型万用分相器的设计和应用：Ⅱ.流动注射溶剂萃取分光？…

设计了一种实用的玻璃重力分相器及相应的萃取流系统,用于在一萃取分光光度测定微量碘,萃取时Ｕ水：Ｕ有机＝３０：１,线性范围在０－３．００ｍｇ／ＬＩ＾－效果良好。