The biogeochemistry of sediments in two Gulf of Maine basins

Pore water, sediment and microbiological samples were collected from two areas in the Gulf of Maine. The Jeffreys Basin sediments had low organic carbon and low reduced sulfur values; the quality of their pore water indicated that nitrification and subsequent denitrification were major biogeochemical processes occurring in the upper 115 cm. Sediments from the Wilkinson Basin had higher values of organic carbon and higher reduced sulfur and total plate-count bacteria. These data indicate that the major biogeochemical processes occurring in these sediments are denitrification followed by sulfate reduction. The differences in the rates of these microbially mediated processes can be related to differences in sedimentation rates at the two sites.     

A new dry combustion method for the simultaneous determination of total organic carbon and nitrogen in seawater

A new dry combustion method for the simultaneous determination of total organic carbon and nitrogen in seawater is presented. Concentrations of total organic carbon obtained using this method average about 2.0 mg/l in surface water and 1.5 mg/l in deep water in the Northwest Atlantic. These concentrations are significantly greater than those reported using wet oxidation and wet combustion methods, but are comparable to concentrations reported by Russian workers using a similar dry combustion method. Organic nitrogen concentrations average 0.44 mg/l in surface water and 0.12 mg/l in deep water, yielding CN ratios for total organic matter of 5 and 12 respectively.     

Book reviews

VANCOUVER'S CHINATOWN: racial discourse in Canada 1875–1980 by K. J. Anderson. 16 × 24 cm, 323 pages. McGill‐Queen's University Press, Montreal, 1991. (ISBN 07735 0844 9) $C34.95 (hard).

GEOGRAPHIC INFORMATION SYSTEMS: developments and applications edited by L. Worrall. 15 × 23 cm, 251 pages. Belhaven, London, 1990. (ISBN 1 85293 140 X) £45.00 (hard).

SAVANNA ECOLOGY AND MANAGEMENT: Australian perspectives and intercontinental comparisons edited by P. A. Werner. 22 × 27 cm, xii and 221 pages. Blackwell Scientific, Oxford, 1991. (ISBN 0 632 03199 9) $A89.00 (soft).

GLOBAL CHANGE AND CHALLENGE: geography for the 1990s edited by R. J. Bennett and R. Estall. 14 × 22 cm, xii and 264 pages. Routledge, London, 1991. (ISBN 0 415 00143 9) $A29.95 (soft).

PLAINS OF PROMISE RIVERS OF DESTINY: water management and the development of Queensland 1824–1990 by J. M. Powell. 17 × 24 cm, xvii and 395 pages. Boolarong Publications, Brisbane, 1991. (ISBN 0 7242 4470 0) $A40.00 (hard).

A SHARED HARVEST: The Australian Wheat Industry, 1939–1989 by G. Whitwell and D. Sydenham. 17 × 25 cm, xi and 324 pages. Macmillan, Melbourne, 1991. (ISBN 0 7329 0584 2) $A29.95 (hard).

TAMING THE GREAT SOUTH LAND: a history of the conquest of nature in Australia by W. J. Lines. 16 × 23cm, xx and 337 pages. Allen & Unwin, Sydney, 1991. (ISBN 1 86373 017 6) $A34.95 (hard).

PLAINS OF PROMISE RIVERS OF DESTINY: water management and the development of Queensland 1824–1990 by J. M. Powell. 17 × 24 cm, xvii and 395 pages. Boolarong Publications, Brisbane, 1991. (ISBN 0 7242 4470 0) $A40.00 (hard).

THE HUMANITIES AND THE AUSTRALIAN ENVIRONMENT: Papers from the Australian Academy of the Humanities Symposium edited by D. J. Mulvaney. 24 × 17 cm, xiii and 123 pages. Australian Academy of the Humanities, Canberra, 1991. (ISBN 0 909897 22 0) $A18.50 posted (soft).

GROWTH (Vol. 167, Sage Library of Social Research) by H. Teune. 141 pages. Sage Publications, Newbury Park, CA, 1988. (ISBN 0 8039 3183 2) US$46.00 (hard); (ISBN 0 8039 3190 5) US$22.95 (soft).

BEYOND GROWTH: elements of sustainable development by U.E. Simonis. 151 pages. Edition Sigma Bohn, Berlin, 1990. (ISBN 3 924859 56 6) DM24.80 (soft).

BEYOND BEEF: the rise and fall of the cattle culture by J. Rifkin. 16 × 24 cm, xi and 353 pages. Viking O'Neil, Melbourne, 1992. (ISBN 0 670 84844 1) $35.00 (hard).

A QUESTION OF PLACE: exploring the practice of human geography by R.J. Johnston. 15 × 23 cm, ix and 280 pages. Blackwell, Oxford, 1991. (ISBN 0 631 18207 1) $39.95 (soft).

GEOGRAPHY IN SOCIETY edited by R. Gerber. 21 × 29 cm, 92 pages. Royal Geographical Society of Queensland, Brisbane, [1992]. (ISBN 0 949286 02 8) $8.00 (soft).     

Solar Wind Control of Jupiter's H3Auroras

A program of observations of Jupiter's H⁺₃auroras was conducted during the first 4 months of 1992, a period that spanned the Ulysses encounter. Daily variations of auroral intensity are small in magnitude (∼20%) and well correlated with variations in the solar wind ram pressure arriving at Jupiter. A much larger (factor of 3) time variation is observed to occur on a time scale of approximately 2 months. During the first 2 months of observation, the inferred total intrinsic intensity of the northern aurora exceeded that of the southern aurora by a factor of 2. Throughout the latter 2 months, characterized by less intense auroral activity, the intensity of the northern aurora was comparable to that of the southern aurora.     

Book reviews

THE CAPITALIST SPACE ECONOMY: Geographical Analysis after Ricardo, Marx and Sraffa by E. Sheppard and T. J. Barnes. 15 × 22 cm, xviii and 328 pages. Unwin Hyman: London 1990 (ISBN 004 330401 X) £40.00 hard; (ISBN 004 330402 8) £14.95 (soft).

THE INTERNATIONAL STEEL INDUSTRY: Restructuring, State Policies and Localities by R. Hudson and D. Sadler. 14 × 22 cm, xii and 163 pages. Routledge: London 1989 (ISBN 0 415 02186 3) $A89.95 (hard).

INDUSTRIAL TRANSFORMATION AND CHALLENGE IN AUSTRALIA AND CANADA (Carleton Library No. 164) edited by R. Hayter and P. D. White. 15 × 23 cm, x and 340 pages. Carleton University Press: Ottawa 1990 (ISBN 0 88629 129 1) $A34.95 (hard); (ISBN 0 88629 128 3) $A 19.95 (soft).

LABOUR MIGRATION. The Internal Geographical Mobility of Labour in the Developed World edited by J. H. Johnson and J. Salt. 15 × 24 cm, viii and 215 pages. David Fulton: London 1990 (ISBN 1 85346 120 2) £30.00 (hard).

CITIES IN SPACE: CITY AS PLACE by D. Herbert and C. Thomas. 15 × 23 cm, xi and 340 pages. David Fulton: London 1990 (ISBN 1 85346 138 5) £35.00 (hard); (ISBN 1 85346 109 1) £14.95 (soft).

THE NEW URBAN FRONTIER. Urbanisation and City Building in Australasia and the American West by L. Frost. 15 × 23 cm, xvii and 226 pages. New South Wales University Press: Sydney (ISBN 0 86840 268 0) $A24.95 (soft).

SYDNEY: A Social Atlas by R. Horvath, G. E. Harrison and R. M. Dowling. 19 × 28 cm, 110 pages. Sydney University Press: Sydney 1989 (ISBN 0 424 00144 6) $A19.95 (soft).

CHANGE AND ADJUSTMENT IN NORTHERN NEW SOUTH WALES edited by D. J. Walmsley. 17 × 23 cm. 118 pages. Department of Geography and Planning, University of New England: Armidale 1990 (ISBN 0 85834 887 X) $A10.00 (soft).

ANNOTATED BIBLIOGRAPHY OF URANIUM IN AUSTRALIA (Cover Title: URANIUM IN AUSTRALIA 1970–1987: An Annotated Bibliography) by C. O'Faircheallaigh, A. Webb and D. Wade‐Marshall. 18 × 25 cm, xi and 306 pages. North Australia Research Unit, Australian National University: Darwin 1989 (ISBN 07315 05433).     

Spectropolarimetry with a cube beamsplitter

For less than $2000 in materials we have exploited the DAO 1.8 m Cassegrain spectrograph between 430 and 800 nm for differential linear spectropolarimetry at resolutions up to 30,000 by using a beamsplitting cube as single-channel analyser. The position angle of the cube is under microprocessor control and, to counteract the highly erratic response of the spectrograph image-slicer combination to linear polarisation, we convert to circular polarisation by inserting a quarter-wave plate. The analyser has 40% throughput (c.f. 50% ideal) and we can sense polarisation levels as small as 0.01% with a CCD. Incomplete action of the quater-wave plate is probably the ultimate limit to precision. Details of the reduction procedure are given together with illustrative results for the Be star Per.     

Speciation and colloid transport of arsenic from mine tailings

In addition to affecting biogeochemical transformations, the speciation of As also influences its transport from tailings at inoperative mines. The speciation of As in tailings from the Sulfur Bank Mercury Mine site in Clear Lake, California (USA) (a hot-spring Hg deposit) and particles mobilized from these tailings have been examined during laboratory-column experiments. Solutions containing two common, plant-derived organic acids (oxalic and citric acid) were pumped at 13 pore volumes d⁻¹ through 25 by 500 mm columns of calcined Hg ore, analogous to the pedogenesis of tailings. Chemical analysis of column effluent indicated that all of the As mobilized was particulate (1.5 mg, or 6% of the total As in the column through 255 pore volumes of leaching). Arsenic speciation was evaluated using X-ray absorption spectroscopy (XAS), indicating the dominance of arsenate [As(V)] sorbed to poorly crystalline Fe(III)-(hydr)oxides and coprecipitated with jarosite [KFe₃(SO₄, AsO₄)₂(OH)₆] with no detectable primary or secondary minerals in the tailings and mobilized particles. Sequential chemical extractions (SCE) of <45 μm mine tailings fractions also suggest that As occurs adsorbed to Fe (hydr)oxides (35%) and coprecipitated within poorly crystalline phases (45%). In addition, SCEs suggest that As is associated with 1 N acid-soluble phases such as carbonate minerals (20%) and within crystalline Fe-(hydr)oxides (10%). The finding that As is transported from these mine tailings dominantly as As(V) adsorbed to Fe (hydr)oxides or coprecipitated within hydroxysulfates such as jarosite suggests that As release from soils and sediments contaminated with tailings will be controlled by either organic acid-promoted dissolution or reductive dissolution of host phases.     

Eruptive styles and inferences about plumbing systems at Hidden Cone and Little Black Peak scoria cone volcanoes (Nevada,U.S.A.)

We describe two small scoria cone volcanoes, Hidden Cone and Little Black Peak (ages between ~320–390 ka), in the Southwestern Nevada Volcanic Field and discuss their eruption mechanisms and inferences about their plumbing systems. Cone-forming pyroclastic deposits are consistent with eruptive styles ranging from Strombolian to violent Strombolian, and lavas emanated from near the bases of the cones. The volcanoes are monogenetic (rather than polycyclic, as allowed by previous geomorphic interpretations). Vents at each volcano appear to coincide with pre-existing normal faults, consistent with observations at older, deeply eroded volcanoes in the region. The existence of these two volcanoes on a topographically high area (particularly Hidden Cone) provides evidence for short feeder dike lengths (~500 m at the surface). We infer that this short length reflects the small length scale of the mantle source region that was tapped to feed each volcano. Editorial responsibility: J Stix     

Visualization and Analysis of Multi-terabyte Geophysical Datasets in an Interactive Setting with Remote Webcam Capabilities

Visualizing and analyzing datasets in the geosciences is becoming increasingly complicated as their volumes are growing explosively. This poses a challenging problem for researchers who must sift through terabytes of data to discover useful relationships inside the information. There is a great need for geophysicists to interactively explore their data sets. Conventional visualization systems lack adequate bandwidth and rendering capabilities necessary for the largest data sets. CAVE and Powerwall display devices are necessary for researchers to explore their data sets in an immersive setting. We describe a utilitarian system targeted specifically at the cost-effective interactive exploration of data sets tens of terabytes in size and harness this system for visualization and analysis of geophysical simulations. Webcams can be used as a steering device to track a local region of interest, which is useful for remote visualization of large data sets. This system will be employed as a web-service under the auspices of Narada-Brokering, while using webcam technologies to enable remote visualization for collaborating researchers. Webcams can be incorporated in a point-to-point network for rapid exchange of information and quickly announcing natural disasters, such as tsunamis, landslides and earthquakes.