Macro- and megafauna communities in three deep basins of the South-East Atlantic

During ‘Meteor’ expedition ‘DIVA 2’ in 2005 the abyssal macro- and megafauna communities were studied in the northern Cape Basin, in the northern Angola Basin and in the eastern and western Guinea Basin. Water depths varied between 5040 and 5670 m.Surface deposit feeding or predatory ophiuroids dominated the megafaunal community in the northern Cape Basin, sponges, sipunculids and fish in the northern Angola Basin, and asteroids, crustaceans and fish in the eastern Guinea Basin, while in the western Guinea Basin sipunculids dominated.In the northern Cape Basin, peracarid crustaceans were the dominant macrofaunal group, followed by polychaetes and bivalves. In the Guinea Basin, polychaetes, peracarid crustaceans and bivalves dominated, although omnivorous or predatory free-living nematodes of macrofaunal size (>0.5 mm) made up 40–60% of the total abundance, with maxima in the western basin.The chlorophyll a content of sediments was lower in the northern Cape and Angola Basins than in the Guinea Basin, which was consistent with the differences in water masses, primary production and flux rate of organic matter in the three basins of the South-East Atlantic. The differences in structure and function of the macro- and megafauna communities in the three basins correlated with the differences in the amount of food reaching the seafloor in tropical and subtropical settings.     

神农架松柏镇水文地球化学研究

近年来，神农架松柏镇居民的结石病时有发生．并有增长的势头。为了解地质环境尤其是饮用水对病患的影响，笔者现场对患病情况以及各种水源(包括河水、泉水、自来水)的来源、化学组成和放射性进行了调查，运用水质常规方法和原子吸收光谱分别测定了离子和微量元素。同时，与地质环境类似的木鱼镇进行了对比调查。研究结果显示，两地地表水、地下水的各种指标均未超出“生活饮用水水源水质卫生标准”。(CJ3020-93)，且松柏镇水体中的放射性(γ射线)低于木鱼镇，而居民的患病率却远高于木鱼镇，可见松柏镇的水环境与居民的结石病无直接关系。     

The annual cycle of peroxides and ozone in marine air at Cape Grim, Tasmania

The concentration of gas-phase peroxides has been measured almost continuously at the Cape Grim baseline station (41° S) over a period of 393 days (7702 h of on-line measurements) between February 1991 and March 1992. In unpolluted marine air a distinct seasonal cycle in concentration was evident, from a monthly mean value of>1.4 ppbv in summer (December) to <0.2 ppbv in winter (July). In the summer months a distinct diurnal cycle in peroxides was also observed in clean marine air, with a daytime build-up in concentration and decay overnight. Both the seasonal and diurnal cycles of peroxides concentration were anticorrelated with ozone concentration, and were largely explicable using a simple photochemical box model of the marine boundary layer in which the central processes were daytime photolytic destruction of ozone, transfer of reactive oxygen into the peroxides under the low-NO_x ambient conditions that favour self-reaction between peroxy radicals, and continuous heterogeneous removal of peroxides at the ocean surface. Additional factors affecting peroxides concentrations at intermediate timescales (days to a week) were a dependence on air mass origin, with air masses arriving at Cape Grim from higher latitudes having lower peroxides concentrations, a dependence on local wind speed, with higher peroxides concentrations at lower wind speeds, and a systematic decrease in peroxides concentration during periods of rainfall. Possible physical mechanisms for these synoptic scale dependencies are discussed.     

土壤重金属地球化学特征及环境评价——以张北县二台镇为例

张家口北部坝上草原地区属于典型的半干旱草原牧区,近年来受到人为活动影响,土地荒漠化加剧,草原生态系统受损严重。本研究依据张北县二台镇土地利用现状边界布设了136个土壤采样点,测定了土壤21个指标。运用主成分分析法与GIS空间插值(IDW)方法来分析土壤中重金属元素的空间迁移富集与分异机理,并采用地累积指数法、潜在生态危害指数法对表层土壤9种重金属元素(Cd、Hg、Mn、Cr、Cu、Pb、Zn、Ni和As)污染程度、生态风险进行评价。结果显示:研究区9种重金属元素土壤环境质量单指标等级评价以一等、低风险土壤为主。根据因子分析和主成分分析,Hg、Pb受人类活动及成土母质控制,其余7种元素均受成土母质的控制。地累积指数结果显示, 9种重金属元素除Hg以外地累积指数均小于0,总体为无污染等级,Hg为中污染等级。潜在生态危害指数结果显示Hg和Cd为潜在危害元素,其中Hg整体达到很强生态危害程度,Cd达到中等生态危害程度,其他元素为轻微生态危害程度。重金属综合生态危害指数(RI)表明在研究区七间窑村—哈拉勿素村以西地区为中等生态危害风险区,其余地区为轻微生态危害风险区。     

民族地区旅游城镇意象空间结构整合优化研究——以甘南藏族自治州碌曲县郎木寺镇为例

意象空间是人对客观世界的主观理解, 是外在形象和内在意蕴的有机统一, 其研究思路多为通过意象群体对其周边环境的感知为目的地建设发展提供借鉴. 为指导藏区民族特色旅游城镇健康持续发展, 以意象空间为研究视角, 通过问卷与访谈调查, 采取照片辨认和认知地图法, 以甘南藏族自治州碌曲县郎木寺镇为例, 对藏区旅游城镇意象空间进行实证研究. 结果表明: 郎木寺镇旅游意象空间呈现"三层空间"的典型结构特征和曼荼罗的意象图式. 以此为基础, 提出各层空间的发展思路及协调组织方式.     

Evolution of drainage patterns on Cape York Peninsula,northeast Queensland

Drainage patterns along passive continental margins are often hypothesised to be the result of drainage disruption following highland uplift and downwarping of the highland flank. Several studies of stream catchments throughout southeast Australia have demonstrated that the opposite tends to be the case in this region because the field evidence favours stream and continental drainage‐divide stability. While significant advances have been made towards understanding this phenomenon in the southeastern corner of the continent, little is known of the evolution of streams and highlands in northeast Australia. Our study examines palaeochannels and fluvial sedimentary units close to the continental drainage divide in six stream catchments along the length of Cape York Peninsula. The results show that four of the catchments (Barron‐Mitchell and Stewart‐Holroyd) have experienced continental divide and drainage stability, whereas the Pascoe‐Wenlock system appears to have experienced westward migration of the continental drainage divide and diversion of the Pascoe River. River diversion here is likely to be a result of the raising of base‐level and flooding of stream channels during the Cretaceous marine transgression and subsequent stream incision by the Pascoe River along structural weaknesses in the underlying strata, following cessation of marine conditions.     

Nature and origin of the Vani manganese deposit, Milos, Greece: an overview

The Vani manganese deposit is located in the rugged NW sector of Milos Island. It occurs within the Vani volcano-sedimentary basin, which is underlain by dacitic domes and flows of Upper Pliocene age (3.5–2.0 Ma). The end of the emplacement of the dacites was marked by the collapse of the magma chamber, which resulted in a huge pyroclastic episode and the deposition of a thick layer of pyroclastic material within a shallow submarine basin. This pyroclastic material subsequently compacted to form the volcaniclastic sandstone, which became the host for the manganese ore beds which were about 4 m thick in the two sections studied. Hydrothermal fluids penetrated these sandstone horizons via fractures and fissures to produce the manganese deposit. The permeable nature of the sandstone facilitated the retention of the hydrothermal fluids within these layers. This permitted the fluids to cool slowly and deposit the manganese oxides almost quantitatively. Formation of the hydrothermal manganese deposit took place fairly rapidly over a period of several tens of thousands of years at most. Strong tectonic activity resulted in rapid uplift of the area which elevated the deposit above sea level.Two generations of manganese oxides have been identified within this deposit; the first generation consists of pyrolusite and ramsdellite; the second generation of oxides of the isostructural series cryptomelane–hollandite–coronadite plus hydrohetaerolite characterized by high contents of K, Ba, Pb and Zn, respectively. This sequence is the result of a two-stage process of formation of the manganese-oxide minerals in which a second high-salinity hydrothermal fluid enriched in Ba, Pb and Zn as a result of the dissolution of sulphide minerals remineralized the original manganese-oxide assemblage. It is this two-stage process of formation, which was mainly responsible for the unique characteristics of this deposit. Although formed in a submarine setting, the deposit shows marked differences in mineralogy and composition from known submarine hydrothermal manganese deposits and is most analogous to the epithermal vein deposits of the southwestern United States.     

亦庄新城规划建设与地质环境的协调性分析

地质环境与城市规划建设息息相关。本文结合亦庄新城规划建设,对地质环境问题进行了分析研究,建立了二者相互影响的模型,并通过系统聚类方法进行了协调性分析,为今后的新城规划中的地质勘查工作提供了工作思路,也为新城规划和合理布局提供了科学依据。     

Regional Sources of Methyl Chloride, Chloroform and Dichloromethane Identified from AGAGE Observations at Cape Grim, Tasmania, 1998–2000

There are large uncertainties in identifying and quantifying the natural and anthropogenic sources of chloromethanes – methyl chloride (CH₃Cl), chloroform (CHCl₃) and dichloromethane (CH₂Cl₂), which are responsible for about 15% of the total chlorine in the stratosphere. We report two years of in situ observations of these species from the AGAGE (Advanced Global Atmospheric Gas Experiment) program at Cape Grim, Tasmania (41° S, 145° E). The average background levels of CH₃Cl, CHCl₃ and CH₂Cl₂ during 1998–2000 were 551± 8, 6.3± 0.2 and 8.9± 0.2 ppt (dry air mole fractions expressed in parts per 10¹²) respectively, with a two-year average amplitude of the seasonal cycles in background air of 25, 1.1 and 1.5 ppt respectively. The CH₃Cl and CHCl₃ records at Cape Grim show clear episodes of elevated mixing ratios up to 1300 ppt and 55 ppt respectively, which are highly correlated, suggesting common source(s). Trajectory analyses show that the sources of CH₃Cl and CHCl₃ that are responsible for these elevated observations are located in coastal-terrestrial and/or coastal-seawater regions in Tasmania and the south-eastern Australian mainland. Elevated levels of CH₂Cl₂ (up to 70 ppt above background) are associated mainly with emissions from the Melbourne/Port Phillip region, a large urban/industrial complex (population 3.5 million) 300 km north of Cape Grim.Now at the Centre for Atmospheric ChemistryNow at School of Environmental Sciences     

江汉平原周老镇钻孔砾石统计及其与长江三峡贯通的关系

对江汉平原周老镇钻孔砾石层砾石的粒度和砾态进行统计和分析的结果表明：砾石的风化程度普遍较高,砾石的扁度、球度、磨圆度、砾态参数（F／ψ）和各轴分选系数均符合河流相沉积物的特征。通过分析砾石粒度和砾态的变化曲线,可将其划分为3个阶段。阶段Ⅰ和Ⅱ的平均砾径、中值砾径、扁度、球度和砾态参数（F／ψ）相差不大,而阶段Ⅲ与阶段Ⅰ、Ⅱ相差很大,阶段Ⅲ的水动力条件、沉积物比阶段Ⅰ、Ⅱ显著增强并混杂了远源物质。结合周老镇钻孔岩性及钻孔砾石含量和江汉平原第四系岩相剖面特征判断,在阶段Ⅲ109．5-117．0m（0．97～1．12Ma．B．P．）处钻孔的沉积环境发生了重大改变,江汉平原水系发生了重要调整,可能是长江贯通三峡。