二氧化碳生物地球化学循环研究的进展

综述了对二氧化碳生物地球化学循环的研究现状，着重介绍了大气二氧化碳的源和汇的研究资料，并简要介绍了有关碳循环模式。     

Cryptic crustal contamination of MORB primitive melts recorded in olivine-hosted glass and mineral inclusions

The origin of compositional heterogeneities among the magmas parental to mid-ocean ridge basalts (MORB) was investigated using a single rock piece of the olivine-phyric basalt from 43°N, Mid-Atlantic Ridge (AII D11-177). The exceptional feature of this sample is presence of very primitive olivine crystals (90–91 mol% Fo) that are significantly variable in terms of CaO (0.15–0.35 wt%). A population of low-Ca olivine (0.15–0.25 wt% CaO) is also notably distinct from high-Ca olivine population in AII D11-177, and primitive MORB olivine in general, in having unusual assemblage of trapped mineral and glass inclusions. Mineral inclusions are represented by high-magnesian (Mg# 90.7–91.1 mol%) orthopyroxene and Cr-spinel, distinctly enriched in TiO₂ (up to 5 wt%, c.f. <1 wt% in common MORB spinel). Glass inclusions associated with orthopyroxene and high-Ti Cr-spinel have andesitic compositions (53–58 wt% SiO₂). Compared to the pillow-rim glass and “normal” MORB inclusions, the Si-rich glass inclusions in low-Ca olivine have strongly reduced Ca and elevated concentrations of Ti, Na, K, P, Cl, and highly incompatible trace elements. Strong variability is recorded among glass inclusions within a single olivine phenocrysts. We argue that the observed compositional anomalies are mineralogically controlled, and thus may arise from the interaction between hot MORB magmas and crystal cumulates in the oceanic crust or magma chamber.     

Atmospheric, oceanic and hydrological contributions to seasonal variations in length of day

 The annual and semiannual residuals derived in the axial angular momentum budget of the solid Earth–atmosphere system reflect significant signals. They must be caused by further excitation sources. Since, in particular, the contribution for the wind term from the atmospheric layer between the 10 and 0.3 hPa levels to the seasonal variations in length of day (LOD) is still missing, it is necessary to extend the top level into the upper stratosphere up to 0.3 hPa. Under the conservation of the total angular momentum of the entire Earth, variations in the oceanic angular momentum (OAM) and the hydrological angular momentum (HAM) are further significant excitation sources at seasonal time scales. Focusing on other contributions to the Earth's axial angular momentum budget, the following data are used in this study: axial atmospheric angular momentum (AAM) data derived for the 10–0.3 hPa layer from 1991 to 1997 for computing the missing wind effects; axial OAM functions as generated by oceanic general circulation models (GCMs), namely for the ECHAM3 and the MICOM models, available from 1975 to 1994 and from 1992 to 1994, respectively, for computing the oceanic contributions to LOD changes, and, concerning the HAM variations, the seasonal estimates of the hydrological contribution as derived by Chao and O'Connor [(1988) Geophys J 94: 263–270]. Using vector representation, it is shown that the vectors achieve a close balance in the global axial angular momentum budget within the estimated uncertainties of the momentum quantities on seasonal time scales. Received: 6 April 2000 / Accepted: 13 December 2000     

On the meridional circulation and balance of momentum in the Southern Ocean of POP

 The circulation of the Southern Ocean is studied in the eddy-resolving model POP (Parallel Ocean Program) by an analysis of zonally integrated balances. The TEM formalism (Transformed Eulerian Mean) is extended to include topography and continental boundaries, thus deviations from a zonally integrated state involve transient and standing eddies. The meridional circulation is presented in terms of the Eulerian, eddy-induced, and residual streamfunctions. It is shown that the splitting of the meridional circulation into Ekman and geostrophic transports and the component induced by subgrid and Reynolds stresses is identical to a particular form of the zonally integrated balance of zonal momentum. In this balance, the eddy-induced streamfunctions represent the interfacial form stresses by transient and standing eddies and the residual streamfunction represents the acceleration of the zonal current by density fluxes in a zonally integrated frame. The latter acceleration term is directly related to the surface flux of density and interior fluxes due to the resolved and unresolved eddies. The eddy-induced circulation is extremely vigorous in POP. In the upper ocean a shallow circulation, reversed in comparison to the Deacon cell and mainly due to standing eddies, appears to the north of Drake Passage latitudes, and in the Drake Passage belt of latitudes a deep-reaching cell is induced by transient eddies. In the resulting residual circulation the Deacon cell is largely cancelled and the residual advection of the zonal mean potential density is balanced by diapycnal eddy and subgrid fluxes which are strong in the upper few hundred meters but small in the ocean interior. The balance of zonal momentum is consistent with other eddy-resolving models; a new aspect is the clear identification of density effects in the zonally integrated balance. We show that the wind stress and the stress induced by the residual circulation drive the eastward current, whereas both eddy species result in a braking. Finally, we extend the Johnson–Bryden model of zonal transport to incorporate all relevant terms from the zonal momentum balance. It is shown that wind stress and induction by the residual circulation carry an eastward transport while bottom form stress and the stress induced by standing eddies yield westward components of transport. Received: 26 June 2001 / Accepted: 2 November 2001     

一个热带太平洋距平模式对风应力异常的响应

本文利用１９７０至１９８９年共２０年的逐月平均的太平着区的表面风应力和海表温度距平的分析资料，检验了以前设计的热带太平洋和热带大气距平模式的模拟性能，通过使用两组风应力异常场即观测场和热带大气模式对观测海温响应所得的模拟场，重点分析了热带太平洋距平模式对风应力异常的响应特征，结果表明，本文海洋距平模式完全有能力再现ＥＮＳＯ循环折际变化性及其水平结构，且赤道中太平洋区域的低频风应力异常对于ＥＮＳＯ事     

Covariations in oceanic dimethyl sulfide,its oxidation products and rain acidity at Amsterdam Island in the Southern Indian Ocean

Simultaneous measurements of rain acidity and dimethyl sulfide (DMS) at the ocean surface and in the atmosphere were performed at Amsterdam Island over a 4 year period. During the last 2 years, measurements of sulfur dioxide (SO₂) in the atmosphere and of methane sulfonic acid (MSA) and non-sea-salt-sulfate (nss-SO₄ ^2-) in rainwater were also performed. Covariations are observed between the oceanic and atmospheric DMS concentrations, atmospheric SO₂ concentrations, wet deposition of MSA, nss-SO₄ ^2-, and rain acidity. A comparable summer to winter ratio of DMS and SO₂ in the atmosphere and MSA in precipitation were also observed. From the chemical composition of precipitation we estimate that DMS oxidation products contribute approximately 40% of the rain acidity. If we consider the acidity in excess, then DMS oxidation products contribute about 55%.     

海洋碳循环模式的进展

本文综述了两类近年来国外使用的海洋碳循环数值模式.一类是国外通常使用的比较简单的箱模式;另一类是基于大洋环流模式的三维无机碳循环模式,以及在该模式的基础上引进了海洋生物群作用的海洋碳循环模式.后者是目前比较完整的模式,也是本文重点介绍的内容.     

益阳火山岩特征及其形成构造环境分析

益阳火山岩中的熔岩、辉长辉绿岩和玄武质科马提岩,分别与蛇绿岩套中的熔岩、熔岩中的脉岩或岩墙杂岩和层状堆晶辉长岩有相似或相同的化学成分与微量元素含量,它们具有蛇绿岩套属性。与邻区广西、江西和安徽等省的蛇绿岩套分布在同一带上。因而认为,湖南境内沿通道—淑浦—宁乡—浏阳一带存在一条元古宙的古板块消减带,它控制了湖南中北部地区大地构造的演化和发展。     

秦岭造山带松树沟元古宙蛇绿岩及其大地构造背景

秦岭造山带松树沟蛇绿岩大约是在９８３Ｍａ，构造就位于秦岭杂岩（Ｐｔ１）之上的异地构造岩片．由变质橄榄岩、堆积橄榄岩和火山岩系组成。变质橄榄岩以纯橄榄岩为主。堆晶岩分为单斜辉石型和斜方辉石型两类。火山岩由拉斑玄武岩和低铝安山岩组成，εＮｄ（Ｔ）为＋４．１～＋６．４，表现出Ｎ、Ｔ、Ｐ三种稀土分配型式和非正常洋脊玄武岩地球化学的特征。综合分析认为，这个古老蛇绿岩是在一种位于洋中脊之上的洋岛环境中形成的，代表了晋宁期华北板块与扬子板块之间古洋盆的残骸。