Structure of Subsurface Intrusion of the Oyashio Water into the Kuroshio Extension and Formation Process of the North Pacific Intermediate Water

In order to understand the actual formation process of the North Pacific Intermediate Water (NPIW), structure of subsurface intrusions of the Oyashio water and the mixing of the Oyashio and the Kuroshio waters in and around the Kuroshio Extension (KE) were examined on the basis of a synoptic CTD observation carried out in May-June 1992. The fresh Oyashio water in the south of Hokkaido was transported into KE region through the Mixed Water Region (MWR) in the form of subsurface intrusions along two main paths. The one was along the east coast of northern Japan through the First Branch of the Oyashio (FBO) and the other along the eastern face of a warm streamer which connected KE with a warm core ring through the Second Branch of the Oyashio (SBO). The fresh Oyashio water extended southward through FBO strongly mixed with the saline NPIW transported by the Kuroshio in the south of Japan (old NPIW) in and around the warm streamer. On the other hand, the one through SBO well preserved its original properties and extended eastward beyond 150°E along KE with a form of rather narrow band. The intrusion ejected Oyashio water lens with a diameter of 50–60 km southward across KE axis and split northward into the MWR involved in the interaction of KE and a warm core ring, which were supposed to be primary processes of new NPIW formation.     

Semidiurnal Dynamics of Salinity, Nutrients and Suspended Particulate Matter in an Estuary in the Seto Inland Sea, Japan, during a Spring Tide Cycle

The physical and chemical variability of the water column at subtidal station of an estuary in the Seto Inland Sea, Japan, was studied over a 24-hour period during a spring tide (tidal range ca. 2 m) in May 1995. Surface water and several depths through the water column were monitored every one and two hours, respectively. At each occasion, water temperature, salinity and dissolved oxygen concentration were measured and water samples were collected for the determination of nutrients and suspended particulate matter (SPM). Disruptive changes in the physical and chemical characteristics of the water was produced by the tidal cycle and the mixing of water masses of different origin. These changes were highly significant both spatially and temporally, yet with varying effects on physical parameters, nutrients and the different components of SPM. Significant differences in nutrient concentrations were also observed when the data-set was divided into ebb and flood components, irrespective of the depth. Nitrate and nitrite rose to 1.8 times higher during the flood. Spatial differences of SPM were less marked than those of nutrients, only particulate organic carbon (POC) being significantly higher at the surface than in the intermediate and the lower layer. Both POC and pheopigment concentrations increased markedly through the water column, being highest shortly before the lower low tide. In contrast, suspended solid (SS) content increased sharply after the lower low tide (>40 mg l⁻¹) and this coincided with a marked decrease of the C/SS content (<20 mg g⁻¹). The lagtime between POC and SS tidal transport was caused by particle resuspension from the exposed intertidal sediments as the tidal level rose, and particle transport selection in relation to the tidal state. This revised version was published online in August 2006 with corrections to the Cover Date.     

高空大气温度变化趋势不确定性的研究进展

IPCC第4次评估报告指出：近50年来,全球对流层温度趋于升高、平流层趋于下降;同时强调了研究结果中普遍存在的不确定性,造成不确定性的主要原因是原始资料、台站选取和不同均一化方法。从理论基础入手,系统地总结了国内、外近年来高空大气温度长期变化趋势的研究成果及其不确定性产生的主要原因,详细介绍了高空大气温度序列的质量控制和均一化方法,并对我国探空台站温度序列的不确定性进行了探讨。利用静力学方法进行质量控制,以最大资料缺测率30%作为序列取舍标准,用两相回归法和再分析序列均一化处理116个中国探空站高空温度序列。研究结果表明,1958年以来我国对流层中低层趋于升温,其中1980年以后升温尤为明显;而平流层下层显示降温。      

氮气、氧气和空气水合物的合成及其拉曼光谱特征

在-20℃和不同的压力下,在实验室内分别合成了氮气水合物(16MPa)、氧气水合物(13MPa)和空气水合物(15MPa),并对其N—N和O—O键伸缩振动的拉曼光谱特征进行了研究。结果表明,人工合成的水合物中的N—N和O—O键的拉曼位移与天然的空气水合物中的数据十分接近。在氮气水合物和空气水合物中,N—N键的拉曼峰值均为2322.4cm-1;O—O键的拉曼峰值在氧气水合物和空气水合物保持一致,均为1547.8cm-1。空气水合物分解的拉曼谱图表明,它不是氮气水合物和氧气水合物组成的混合物,而是由氮分子和氧分子共同生成的单一水合物,氮分子和氧分子同时进入水合物的大笼和小笼中。与空气中的氮、氧比例相比,水合物中氧分子明显富集,氮分子和氧分子的比例为2.4∶1。     

太原盆地农田区大气降尘对土壤重金属元素 累积的影响及其来源探讨

通过研究太原盆地大气干湿沉降中重金属元素的含量分布特征及年输入通量,讨论其对土壤中重金属元素累积的影响。同时采用富集因子法探讨降尘物质的来源。研究结果表明,降尘中重金属元素As、Cd主要来源于人为活动,Pb的来源可能是人为源和自然源。而Hg则主要来源于自然源。     

An evaluation of residential air radon concentrations and related variables in southeast Michigan,USA

Analysis of 153 residential air radon (Rn-222) screening measurements from southeast Michigan indicates that basements host Rn levels two to three times higher than upper-level rooms. Compared to unfinished basements, finished (e.g., paneled walls, tiled floors) basements apparently reduce indoor air Rn levels while partially finished basements may not. Factor analysis of residence questionnaire data explains 59 percent of the Rn data variance. The volume of pathways (e.g., foundation cracks/holes, uncapped sumps) allowing Rn seepage into the dwelling controls the largest portion, 23 percent, of the explained data variance. The residence water source explains 11 percent of the Rn data variance. Groundwater Rn levels contribute to the air Rn data variability, but the study data cannot quantitatively assess this contribution. Seven percent of the Rn data variance is likely controlled by house depressurization facilitated by residence structural properties. Residences with foundation cracks or poorly sealed joints and low-volume indoor-outdoor air exchange are more prone to this effect. Eighteen percent of the explained Rn data variance correlates with the residence's primary heat source. Evidently, operating combustion sources also induce house depressurization and allow Rn to be drawn into the house through entry paths. Twenty-four percent of the analyses equal or exceed 4 pCi/1 Rn. In residences occupied 5 years by the same individuals, 17 percent of the Rn data are 4 pCi/l; here the arithmetic mean air Rn level is 8.3 pCi/l and the average occupancy period 17.4 years.     

Modelling of the vertical fluxes of nitric acid,ammonia, and ammonium nitrate

Results from numerical investigations regarding the exchange of HNO₃, NH₃, and NH₄NO₃ between the atmosphere and the biosphere are presented. The investigations were performed with a modified inferential method which is based on the generally accepted micrometeorological ideas of the transfer of momentum, sensible heat and matter near the Earth's surface and the chemical reactions among these nitrogen compounds. This modified inferential method calculates the micrometeorological quantities (such as the friction velocity and the fluxes of sensible and latent heat), the height-invariant fluxes of the composed chemically conservative trace species with group concentrationsc ₁=[HNO₃]+[NH₄NO₃] (total nitrate),c ₂=[NH₃]+[NH₄NO₃] (total ammonia), andc ₃=[HNO₃]-[NH₃] as well as the fluxes of the individual nitrogen compounds. The parameterization of the fluxes is based on the flux-gradient relationships in the turbulent region of the atmospheric surface layer. The modified inferential method requires only the data of wind velocity, temperature, humidity and concentrations (HNO₃, NH₃, and NH₄NO₃) measured at a reference height by stations of a monitoring network.     

The history and impact of air pollution at Čertovo Lake,southwestern Czech Republic

This multi-disciplinary investigation documents the longterm effects of atmospheric pollution of metals and acids on a geologically sensitive catchment in the umava Mountains, southwestern Czech Republic, a region with a long history of human disturbance. A 30 cm long sediment core (I) from ertovo Lake was analyzed for natural and artifical radionuclides, metals, diatoms, chrysophytes, and pollen in sediments accumulated during the last 200 years. A second core (II), extending to 95 cm, included sediment judged to be free of atmospheric deposition of pollutants associated with the Industrial Revolution. Chronostratigraphic markers include several changes in the pollen assemblages corresponding to well-documented changes in land-use, and distinct distributions of ¹³⁷Cs, ¹³⁴Cs and ²⁴¹Am from weapons testing and the 1986 nuclear accident at Chernobyl, Russia. These markers corroborate the ²¹⁰Pb dating and, together, produce a reliable chronology extending back nearly to 1800 A.D.Stratigraphic profiles of Cu, Pb, and Zn in Core I are unlike any previously reported in the literature. Concentrations of Cu, Pb, and Zn remain generally above 100, 400, and 200 g g^-1, respectively, for the 200 years represented by Core I. These values are unusually high for sediments from a watershed with no known heavy-metal ore bodies. Accumulation rates for Cu, Pb, and Zn, which include both atmospheric and watershed contributions, are also high (ca 1, > 1 and > 1 g cm^-2 yr^-1, respectively) for the same period, although the anthropogenic contribution of Zn rose from nearly zero at 1800 A.D. The Cu and Pb accumulation rates rose dramatically about 1640 A.D.Accumulation rates of anthropogenically-derived Be, a relatively abundant element in the soft coals of the region, are also elevated by about 0.01 g cm^-2 yr^-1 in sediments of this period. Vanadium accumulation rates increased only since 1980 A.D., presumably along with increased consumption of oil.Diatom assemblages illustrate that the lake was acidic (pH between 4.5 and 5) through at least the past 200 years. The pH declined significantly (from ca 5 to 4) between 1960 and 1985 with a slight increase to 4.5 in the last few years. Recent diatom and chrysophyte assemblages suggest high trace metal concentrations, consistent with the present lake-water chemistry.     

硫铅酸盐“S”型瞬凝水泥干法护壁堵漏技术研究

介绍了硫铝酸盐“Ｓ”型瞬凝水泥干法者漏时使用的配方,阐述了输送工具和扫孔钻具的设计以及灌注工艺技术。