吉林东南部晚中生代中酸性火山作用成因的地球化学制约

详细的主、微量元素和Sr-Nd-Pb同位素研究结果显示,延吉地区晚中生代(早白垩世)中酸性火山岩具有岛弧型微量元素特征(富集轻稀土(LREE)、大离子亲石元素(LILE)和亏损高场强元素(HFSE)),和中等放射成因Sr、Pb及类似于硅质地球的Nd同位素组成(~(87)Sr/~(86)Sr(i)=0.70437～0.70525;~(206)Pb/~(204)Pb(i)=18.19～18.37,~(207)Pb/~(204)Pb(i)=15.54～15.57,~(208)Pb/~(204)Pb(i)=38.13～38.22;ε_(Nd)(t)=-2.75～+1.61)。其Sr-Nd-Pb同位素组成特征类似于区域同期基性火山岩和大兴安岭地区同时代火山岩。这些广泛分布于吉林南部的晚中生代中酸性火山岩是岩石圈地幔来源岩浆经分离结晶或地壳物质混染/AFC过程的产物。吉林省东南部晚中生代不同区域火山岩的Sr-Nd-Pb同位素对比结果显示,辽源-延吉与通化地区分属不同构造单元,其中辽源-延吉一带则为中亚造山带的东段,而通化地区为华北克拉通的一部分,夹皮沟-松江断裂可能是华北克拉通东北缘的边界。     

Sound velocity profile estimation: a system theoretic approach

A system-theoretic approach is proposed to investigate the feasibility of reconstructing a sound velocity profile (SVP) from acoustical hydrophone measurements. A state-space representation of the normal-mode propagation model is used. It is shown that this representation can be utilized to investigate the so-called observability of the SVP from noisy measurement data. A model-based processor is developed to extract the required information, and it is shown that even in cases where limited SVP information is available, the SVP can be estimated using this approach. Based on this framework, investigations are made of model-based solutions to the sound velocity profile and related parameter estimation problems. In particular, a processor is designed that allows in situ recursive estimation of the sound velocity profile from simulated data     

Improving the prospects for detecting extrasolar planets in gravitational microlensing events in 2002

Gravitational microlensing events of high magnification have been shown to be promising targets for detecting extrasolar planets. However, only a few events of high magnification have been found using conventional survey techniques. Here we demonstrate that high-magnification events can be readily found in microlensing surveys using a strategy that combines high-frequency sampling of target fields with on-line difference imaging analysis. We present 10 microlensing events with peak magnifications greater than 40 that were detected in real-time towards the Galactic bulge during 2001 by the Microlensing Observations in Astrophysics (MOA) project. We show that Earth-mass planets can be detected in future events such as these through intensive follow-up observations around the event peaks. We report this result with urgency as a similar number of such events are expected in 2002.     

Book reviews

AN AUSTRALIAN DICTIONARY OF ENVIRONMENT AND PLANNING by A. Gilpin. 16 × 24 cm, xvi and 271 pages. Oxford University Press: Melbourne 1990 (ISBN 0 19 554806 X) $A60.00 (hard).

CONTINENT IN CRISIS: A Natural History of Australia by D. Smith, 13 × 20 cm, xii and 201 pages. Penguin: Melbourne 1990 (ISBN 0 14 011169 7) $A14.99 (soft).

THE END OF NATURE by B. McKibben. 14 × 22 cm, xi and 212 pages. Viking: London 1990 (ISBN 0 670 82877 7) $A29.99 (hard); distributed by Penguin Books.

THE FATE OF THE FOREST: Developers, Destroyers and Defenders of the Amazon by S. Hecht and A. Cockburn. 13 × 20 cm, xiii and 349 pages. Penguin: London (ISBN 0 14 013382 8) $A16.99 (soft).

ENVIRONMENT, AID AND REGIONALISM IN THE SOUTH PACIFIC (Pacific Research Monograph No. 22) by J. Carew‐Reid. 17 × 25 cm, xii and 185 pages. National Centre for Development Studies, Australian National University: Canberra 1989 (ISBN 0 7315 0673 1) $A25.00 (soft).

NEW SEEDS AND POOR PEOPLE by M. Lipton with R. Longhurst. 14 × 21 cm, xiv and 473 pages, Unwin Hyman: London 1989 (ISBN 0 04 45326 4) $A39.95 (soft).

CLIMATE CHANGE AND WORLD AGRICULTURE by M. Parry. 15 × 23 cm, xv and 157 pages. Earthscan: London 1990 (ISBN 1 85383 065 8) £9.95 (soft).

INTRODUCTION TO WORLD VEGETATION (Second Edition) by A. S. Collinson. 14 × 21 cm, x and 325 pages. Unwin Hyman: London 1988 (ISBN 0 04 581 030 3) $A95.00 (hard); (ISBN 0 04 581 031 1) $A39.95 (soft).

OCEANS OF LIFE OFF SOUTHERN AFRICA edited by A. I. L. Payne and R. J. M. Crawford. 22 × 29 cm, xii and 380 pages. Vlaeberg: Cape Town 1989 (ISBN 0 947461 01 9) $US30.00 plus $US5.00 postage (hard).

KARST GEOMORPHOLOGY AND HYDROLOGY by D. Ford and P. Williams. 15 × 23 cm, xv and 601 pages. Unwin Hyman: London 1989 (ISBN 0 04 551106 3) $A79.95 (soft).

ENVISIONING INFORMATION by E. R. TUFTE. 22 × 78 cm, 126 pages. Graphics Press: Cheshire, CT 1990 $US48.00 (hard). Available from Graphics Press, Box 430, Cheshire, Connecticut, 06410, USA.

A GUIDE TO REMOTE SENSING: Interpreting Images of the Earth by S. A. Drury. 22 × 27 cm, viii and 199 pages. Oxford University Press: Oxford 1991 (ISBN 0 19 854495 2) $A44.95 (soft).

THE CAINOZOIC IN AUSTRALIA: A Re‐appraisal of the Evidence (Special Publication No. 18) edited by M. A. J. William, P. De Deckker and A. P. Kershaw. 17 × 25 cm, x and 346 pages. Geological Society of Australia Inc: Sydney 1991 (ISBN 0 909869 76 6) $A60.00 (non‐members), $A40.00 (members) (soft).

MONSOONAL AUSTRALIA: Landscape, Ecology and Man in the Northern Lowlands edited by C. D. Haynes, M. G. Ridpath and M. A. J. Williams. 20 × 29 cm, xii and 231 pages. Balkema: Rotterdam 1991 (ISBN 90 6191 638 0) $A85.25 (hard).

SOILS: THEIR PROPERTIES AND MANAGEMENT: A Soil Conservation Handbook for New South Wales edited by P. E. V. Charman and B. W. Murphy. 21 × 27 cm, xix and 363 pages. Sydney University Press: Sydney 1991 (ISBN 0 424 00183 7) $A39.95 (soft).

VEGETATION (Atlas of Australian Resources, Third Series, Volume 6) by Australian Surveying and Land Information Group. 30 × 43 cm, 64 pages. Australian Surveying and Land Information Group: Canberra 1990 (ISBN 0 642 14993 3) $A39.95 (soft).

THE ATLAS OF NEPAL IN THE MODERN WORLD by M. Sill and J. Kirkby. 27 × 22 cm, 160 pages. Earthscan: London 1991 (ISBN 1 85383 032 1) £37.50 (hard).

DEVELOPMENT IN PRACTICE: Paved With Good Intentions by D. Porter, B. Allen and G. Thompson. 15 × 23 cm. Routledge: London 1990 (ISBN 0 415 16626 3) $A27.95 (soft); distributed by The Law Book Co.

CHINA'S SPATIAL ECONOMY: Recent Developments and Reforms edited by G. J. R. Linge and D. K. Forbes. 15 × 22 cm, xiii and 225 pages. Oxford University Press: Hong Kong 1991 (ISBN 0 19 585296 6) $A29.95 (hard).     

Effects of heavy metals on phagocytosis by Molluscan hemocytes

The effects of ten heavy metal cations on phagocytosis of polystyrene latex spheres by hemocytes of the American oyster, Crassostreavirginica, were investigated. Exposure to 1 and 5 ppm Cd²⁺, 5 ppm Co²⁺, 1 ppm Cr³⁺, 1 ppm Cu²⁺, 0·5 ppm Fe³⁺, 0·05 ppm Hg²⁺, 1 and 5 ppm Mn²⁺, 1 and 5 ppm Pb²⁺, 1 ppm Sn²⁺, and 1 and 5 ppm Zn²⁺ resulted in no alteration of phagocytic ability. However, exposure to 1 ppm Co²⁺, 5 ppm Cu³⁺, 5 ppm Cu²⁺, 1 and 5 ppm Fe³⁺, 0·1 ppm Hg²⁺ and 5 ppm Sn²⁺ resulted in significantly enhanced uptake of polystyrene spheres. Finally, exposure to 0·5, 1 and 5 ppm Hg²⁺ resulted in inhibition of phagocytosis and increased cell death.     

A pendulum inclinometer for use with small deep-submersibles

The authors developed a pendulum inclinometer suitable for use with small deep-submersibles or surface craft. The instrument uses a relatively short heavy pendulum and a viscous damping system for minimizing the effects of unwanted oscillatory motion. The pendulum relative motion is transmitted to the dial pointer through a flexible cord. The mechanism is designed so that the inclinometer gives a direct reading of the tangent of the angle of inclination. Adjustments are provided for levelling the instrument and for setting the dial to zero. Upper and lower clamping devices protect the pendulum suspension from damage during transit. The inclinometer has been used successfully in recent inclining experiments for the small research submarine Alvin.     

Variability of physical and chemical characteristics along the 70-m isobath of the southeastern Bering Sea

From observations of ice cover, temperature, salinity, currents and nitrate, it is evident that along-shelf variability was significant over the middle shelf of the eastern Bering Sea, but less distinct than that observed in the cross-shelf domains. Along the 70-m isobath, three zones were evident in the summer: the southeastern cold pool (centered at 57°N); an intermediate zone, consisting of warmer water, with weaker stratification; and the northern cold pool, extending northward from 58°N. Small-scale (20 km) horizontal features that persisted for months were common. Nutrient concentrations were related to salinity and were replenished more uniformly over the southern shelf, than north of the Pribilof Islands. Although mean currents were weak (1 cm s⁻¹), short energetic advective events impacted the temperature and salinity structure.     

Cryptic Blooms: Are Thin Layers the Missing Connection?

Harmful algal blooms (HABs) are common in Monterey Bay, CA, and have resulted in repeated closures of shellfish fisheries and the poisoning and death of marine mammals. In the majority of instances, HAB events in this region are first detected by the presence of sick or dying animals. The phrase “cryptic blooms” was adopted to denote the appearance of poisoning at higher trophic levels with no prior evidence of a large phytoplankton bloom. We hypothesize that the onset of many HAB events goes undetected because the bloom is initially concentrated in discrete thin subsurface layers in the water column that are easily missed by conventional sampling and monitoring methods. In this paper, we report on the detection and monitoring of a subsurface layer of phytoplankton in northern Monterey Bay, CA, using a high-resolution, autonomous profiler. This ‘thin layer,’ which measured from 10 cm to 3 m in thickness (85% < 2 m; 54% < 1 m), persisted over a 7-day period near the base of the pycnocline. The phytoplankton assemblage in the layer was primarily composed of a multi-species assemblage of Pseudo-nitzschia including the toxin-producing species Pseudo-nitzschia australis. Concentrations of toxic phytoplankton (P. australis), cyanobacteria, and bacteria in the layer were significantly higher than outside the layer (P < 0.05). Counts of total Pseudo-nitzschia spp. showed similar levels of enrichment in the layer compared to outside the layer. Our findings indicate that, when monitoring for HABs, it is critical to sample at scales appropriate to resolve thin layers. Thin layers have been identified as a common recurrent feature in a variety of coastal systems, suggesting that the use of autonomous high-resolution vertical profilers coupled with targeted sampling, could allow more timely detection of HABs in many coastal environments.