Geochemistry of suspended matter from the Baltic Sea 2. Results of bulk trace metal analysis by AAS     

Lutz Brügmann  Paul C. Bernard  Rene van Grieken 《Marine Chemistry》1992,38(3-4)

In 1984, on a transect covering the whole Baltic Sea and parts of the adjacent North Sea, 160 water samples were taken and analysed for their concentrations of particulate and dissolved metals. In addition, the suspended materials were investigated for their elemental bulk composition.The particulate fractions represented from about 5% (Cd, Cu and Ni) to 50% (Fe and Pb) of the total (particulate plus dissolved) concentrations. For some elements (Ba, Cd, Cu, Pb and Zn), the particulate matter from the surface microlayer was enriched with respect to those suspended materials taken from 0.2 m depth. This could reflect the atmospheric input of metal-rich aerosols. In anoxic deep waters, maximum contents of Zn (6400 μg g⁻¹), Cu (1330 μg g⁻¹) and Cd (12 μg g⁻¹) were observed in the particulate matter, indicating sulphidic forms. On the other hand, under oxic conditions the distribution coefficients (K_d) decreased with the water depth (Cd, Fe and Pb).Relative to global background levels, the particulate matter contained metal “excesses” amounting to more than 90% of the total contents (Cd, Mn, Pb and Zn). Automated electron probe X-ray microanalysis (EPXMA) revealed that the elemental composition of sediments is mainly governed by post-depositional processes of early diagenesis and is only weakly related to the composition of suspended matter in the overlying water body. For instance, in relation to surface mud sediments of the central Baltic net-sedimentation basins, Zn, Cd, Cu and Mn had 30–100% higher levels in the suspended materials. The general pattern of metal contents of particulate matter taken from 10 m depth on a transect between the Bothnian Bay and the North Sea were—possibly as a result of anthropogenic inputs—rather similar for Pb, Zn and Cu. For Fe and Mn, the distribution patterns along the transect were probably governed by the natural loading characteristics and by the biogeochemistry of those elements.  相似文献   

Reproductive variability in North Sea plaice, sole, and cod   总被引：4，自引：1，他引：4  

Rijnsdorp  A. D.; Daan  N.; van Beek  F. A.; Heessen  H. J. L. 《ICES Journal of Marine Science》1991,47(3):352-375

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Aquatic surface microlayer contamination in chesapeake bay   总被引：1，自引：0，他引：1  

John T. Hardy  Eric A. Crecelius  Liam D. Antrim  Steven L. Kiesser  Virginia L. Broadhurst 《Marine Chemistry》1990,28(4)

The aquatic surface microlayer (SMIC), 50 μm thick, serves as a concentration point for metal and organic contaminants that have low water solubility or are associated with floatable particles. Also, the eggs and larvae of many fish and shellfish species float on, or come in contact with, the water surface throughout their early development. The objectives of this study were (1) to determine the present degree of aquatic surface microlayer pollution at selected sites in Chesapeake Bay, and (2) to provide a preliminary evaluation of sources contributing to any observed contamination.Twelve stations located in urban bays, major rivers, and the north central bay were sampled three times, each at 5-day intervals during May 1986. Samples of 1.4–4.1 each were collected from the upper 30–60-μm water surface (surface microlayer, SMIC) using a Teflon-coated rotating drum microlayer sampler. One sample of subsurface water was collected in the central bay.At all stations, concentrations of metals, alkanes, and aromatic hydrocarbons in the SMIC were high compared with one bulk-water sample and with typical concentrations in water of Chesapeake Bay and elsewhere. SMIC contamination varied greatly among the three sampling times, but high mean contaminant levels (total polycyclic aromatic hydrocarbons, 1.9–6.2 μg 1⁻¹; Pb, 4.9–24 μg 1⁻¹; Cu, 4–16 μg 1⁻¹; and Zn, 34–59 μg 1⁻¹) were found at the upper Potomac and northern bay sites. Three separate areas were identified on the basis of relative concentrations of different aromatic hydrocarbons in SMIC samples - the northern bay, the Potomac River, and the cleaner southern and eastern portions of the sampling area.Suspected sources of surface contamination include gasoline and diesel fuel combustion, coal combustion, and petroleum product releases. Concentrations of metals and hydrocarbons, at approximately half the stations sampled, are sufficient to pose a threat to the reproductive stages of some fish and shellfish. Sampling and analysis of the surface microlayer provides a sensitive tool for source identification and monitoring of potentially harmful aquatic pollution.  相似文献   

Provenance and dispersal of muds south of the Aleutian arc,north Pacific Ocean     

Michael B. Underwood  Eric G. Hathon 《Geo-Marine Letters》1989,9(2):67-75

X-ray diffraction analyses show that the clay mineralogies of near-surface muds in the Gulf of Alaska (mostly illite and chlorite) are consistent with detrital sources in southern Alaska. Expandable clay minerals are derived from the Aleutian volcanic arc, and their percentages increase progressively toward the west. Smectite values are lower than expected, however, particularly in the central forearc, and there is less smectite on the insular trench slope than farther seaward. The regional clay-mineral distribution is controlled by two opposed contour currents and by the influx of suspended sediment via both transverse and trench-axis turbidity currents.  相似文献   

Genetic impacts of shrimp trawling on red snapper (Lutjanus campechanus) in the northern Gulf of Mexico     

Saillant  Eric; Bradfield  S. Coleen; Gold  John R. 《ICES Journal of Marine Science》2006,63(4):705-713

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Improving communication from managers to fishers in Europe and the US     

van Densen  Wim L. T.; McCay  Bonnie J. 《ICES Journal of Marine Science》2007,64(4):811-817

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SeagrassNet monitoring across the Americas: case studies of seagrass decline   总被引：2，自引：0，他引：2  

Frederick T. Short  Evamaria W. Koch  Joel C. Creed  Karine M. Magalhães  Eric Fernandez  & Jeffrey L. Gaeckle 《Marine Ecology》2006,27(4):277-289

Seagrasses are an important coastal habitat worldwide and are indicative of environmental health at the critical land–sea interface. In many parts of the world, seagrasses are not well known, although they provide crucial functions and values to the world's oceans and to human populations dwelling along the coast. Established in 2001, SeagrassNet, a monitoring program for seagrasses worldwide, uses a standardized protocol for detecting change in seagrass habitat to capture both seagrass parameters and environmental variables. SeagrassNet is designed to statistically detect change over a relatively short time frame (1–2 years) through quarterly monitoring of permanent plots. Currently, SeagrassNet operates in 18 countries at 48 sites; at each site, a permanent transect is established and a team of people from the area collects data which is sent to the SeagrassNet database for analysis. We present five case studies based on SeagrassNet data from across the Americas (two sites in the USA, one in Belize, and two in Brazil) which have a common theme of seagrass decline; the study represents a first latitudinal comparison across a hemisphere using a common methodology. In two cases, rapid loss of seagrass was related to eutrophication, in two cases losses related to climate change, and in one case, the loss is attributed to a complex trophic interaction resulting from the presence of a marine protected area. SeagrassNet results provide documentation of seagrass change over time and allow us to make scientifically supported statements about the status of seagrass habitat and the extent of need for management action.  相似文献   

Measurement of the signal to noise ratio in seismic profiling     

Kees Rutten  Mathée Valeton  Theo van Grunsven 《Marine Geophysical Researches》1972,1(4):445-450

The measurement of the signal to noise ratio in continuous seismic profiling systems is carried out by means of a small general purpose digital computer equipped with an analog to digital converter. The computer is programmed to compute and compare the power spectrum of a sample of noise to the power spectrum of a sample of noise plus an echo. Power spectra of some twenty to fifty shots are averaged to yield reliable estimates of the signal to noise ratio as a function of frequency. The observed spectra agree well with spectra calculated from signals measured near to an air-gun. This measurement of signal to noise ratio as a function of frequency provides unambiguous information for the adjustment of the necessary band-pass filter thus improving the operation of a continuous seismic profiler.  相似文献   

Numerical modeling of nonlinear water waves over heterogeneous porous beds   总被引：1，自引：0，他引：1  

Eric C. Cruz  Qin Chen   《Ocean Engineering》2007,34(8-9):1303-1321

The transformation of nonlinear water waves over porous beds is studied by applying a numerical model based on Chen's [2006. Fully nonlinear Boussinesq-type equations for waves and currents over porous beds. Journal of Engineering Mechanics, 132:2, 220–230] Boussinesq-type equations for highly nonlinear waves on permeable beds. The numerical model uses a high-order time-marching solution and fourth-order finite-difference schemes for discretization of first-order spatial derivatives to obtain a computational accuracy consistent with the model equations. By forcing the wave celerity and spatial porous-damping rate of the linearized model to match the exact linear theory for horizontal porous bed over a prescribed range of relative depths, the values of the model parameters are optimally determined. Numerical simulations of the damped wave propagation over finite-thickness porous layer demonstrate the accuracy of both the numerical model and governing equations, which have been shown by prior theoretical analyses to be accurate for both nominal and thick porous layers. These simulations also elucidate on the significance of the higher-order porous-damping terms and the influence of the hydraulic parameters. Application of the model to the simulation of the wave field around a laboratory-scale submerged porous mound provides a measure of its capability, as well as useful insight into the scaling of the porous-resistance coefficients. For application to heterogeneous porous beds, the assumption of weak spatial variation of the porous resistance is examined using truncated forms of the governing equations. The results indicate that the complete set of Boussinesq-type equations is applicable to porous beds of nonhomogeneous makeup.  相似文献   

Book reviews     

R. W. Johnson  P. J. Stephenson  Janet Hooke  Howard A. Bridgman  Eric A. Colhoun  R. W. Young 《The Australian geographer》1989,20(1):99-121

THE IMPACT OF VOLCANIC HAZARDS AT RABAUL, PAPUA NEW GUINEA (Discussion Paper No. 33) by R. J. Blong and C. Aislabie. 17 × 25 cm, xiv and 207 pages. Institute of National Affairs: Port Morseby 1988 (ISBN 9980 77 086 4).

A PRACTICAL APPROACH TO SEDIMENTOLOGY by R. C. Lindholm. 15 × 23 cm, xviii and 279 pages. Allen & Unwin: London 1987 (ISBN 0 04 551132 2) $A45.00 (soft).

THE ATMOSPHERE AND WEATHER OF SOUTHERN AFRICA by R. A. Preston‐Whyte and P. D. Tyson. 18 × 24 cm, xiii and 375 pages. Oxford University Press: Cape Town 1988 (ISBN 0 19 570 514 9) R56.00 (hard); (ISBN 0 19 570 496 7) R39.14 (soft).

QUATERNARY PALEOCLIMATOLOGY: Methods of Paleoclimatic Reconstruction by R. S. Bradley. 15 × 23 cm, xvii and 472 pages. Allen & Unwin: Boston 1985 (ISBN 0 04 551067 9) $A69.95 (hard); (ISBN 0 04 551068 7) $A39.95 (soft).

PROCESSES IN PHYSICAL GEOGRAPHY by R. D. Thompson, A. M. Mannion, C. W. Mitchell, M. Parry and J. R. Townsend. 24 × 19 cm, xii and 380 pages. Longman: London 1986 (ISBN 0 582 30136) $A44.95.

PERSPECTIVES ON A DYNAMIC EARTH by T. R. Paton. 16 × 24 cm, 142 pages. Allen & Unwin: London 1986 (ISBN 0 04 55 0043 6) $A23.95 (soft).

LAND DEGRADATION AND SOCIETY edited by P. Blaikie and H. Brookfield. 15 × 23 cm. xxiv and 296 pages. Methuen: London 1987 (ISBN 0 416 40150 3) $A32.95 (soft).

THE PENGUIN DICTIONARY OF HUMAN GEOGRAPHY by B. Goodall. 13 × 20 cm, 509 pages. Penguin: Harmondsworth 1987 (ISBN 0 14 051095 8) $A19.95 (soft).

MAKING SENSE OF DEVELOPMENT: An Introduction to Classical and Contemporary Theories of Development and Their Application to South‐east Asia by P. W. Preston. 14 × 22 cm, xxi and 318 pages. Routledge & Kegan Paul: London 1986 (ISBN 0 7102 0813 8) $A87.95 (hard).

THE DEMOGRAPHIC DIMENSION IN INDONESIAN DEVELOPMENT by G. J. Hugo, T. H. Hull, V. J. Hull and G. W. Jones. 16 × 25 cm, xxv and 417 pages. Oxford University Press: Singapore 1987 (ISBN 0 19 582699 X) $A49.95 (hard).

GLOBAL ISSUES AND OUTLOOK IN PULP AND PAPER edited by G. F. Schreuder, 18 × 26 cm, ix and 302 pages. University of Washington Press: Seattle 1988 (ISBN 0 295 96642 4) $US40.00 (hard).

AN HISTORICAL GEOGRAPHY OF MODERN AUSTRALIA: The Restive Fringe (Cambridge Studies in Historical Geography No. 11) by J. M. Powell. 16 × 33 cm, xx and 400 pages. Cambridge University Press: Cambridge 1988 (ISBN 0 521 25619 4) $A39.95 (hard).

HISTORICAL GEOGRAPHY: Progress and Prospect edited by M. Pacione. 14 × 22 cm, 306 pages. Croom Helm: London 1987 (ISBN 0 7099 40467) $A27.50 (hard).

THE ROLE OF THEORY IN URBAN PLANNING: A Study of Metropolitan Planning in Perth, Western Australia (Geowest No. 24) by O. Yiftachel. 21 × 29 cm, 102 pages. Department of Geography, University of Western Australia: Nedlands 1987 (ISBN 0 86422 063 4).

SYDNEY INTO ITS THIRD CENTURY: Metropolitan Strategy for the Sydney Region by NSW Department of Environment and Planning. 21 × 29 cm, 72 pages. NSW department of Environment and Planning: Sydney 1988 (ISBN 0 7305 4312 9).

BUS SERVICES IN WESTERN SYDNEY: Private Bus Operators and Government Transport Departments (Monograph Series No. 3) by P. Tranter. 21 × 29 cm, v and 98 pages. Department of Geography and Oceanography, University College, Australian Defence Force Academy: Campbell, ACT 1988 (ISBN 0 7317 0036 8).

AGEING IN VICTORIA: An Electronic Social Atlas by A. L. Howe, P. Newton and P. Sharwood. 30 × 21 cm, 105 pages. National Research Institute for Gerontology and Geriatric Medicine, Mt. Royal Hospital and University of Melbourne: Melbourne 1987 (ISBN 0 958326 6 2) $A10.00 (soft).

READINGS IN AUSTRALIAN GEOGRAPHY: Proceedings of the 21st Institute of Australian Geographers’ Conference, Perth 10–18 May 1986, edited by A. Conacher. 21 × 29 cm, vi and 493 pages. Institute of Australian Geographers (WA Branch) and Department of Geography, University of Western Australia: Perth 1987 (ISBN 0 909678 30 B) $A25.00 (soft).

GEOGRAPHY RESEARCH PROJECTS: A Senior Student's Handbook by H. Binden and H. Williams. 18 × 26 cm, 149 pages. Edward Arnold Australia: Caulfield East 1988 (ISBN 0 7131 8311 X) $A 14.95 (soft).

OUR AMERICAN LAND: 1987 Yearbook of Agriculture, ix and 323 pages. US Government Printing Office, Washington, DC: 1987 $US9.50.

THE ENCYCLOPAEDIC DICTIONARY OF PHYSICAL GEOGRAPHY edited by A. Goudie et al. 17 × 24 cm, xvi and 528 pages. Basil Black‐well: Oxford 1988 (ISBN 0 631 15581 3) $A34.95 (soft).

THE CONSERVATION OF ECOSYSTEMS AND SPECIES by Gareth E. Jones, 14 × 22 cm, 277 pages. Croom Helm: London 1987 (ISBN 0 7099 1463 6) $A87.95 (hard).

SO CAME THEY SOUTH by R. Clancy and A. Richardson. 35 × 35 cm, 176 pages. Shakespeare Head: Sydney 1988 (ISBN 0 7302 0864 8) $A34.95.  相似文献