Silica diffusion at Ascutney Mountain,Vermont

A suite of pelitic schists from the contact metamorphic aureole around the syenite stock at Ascutney Mountain, Vermont, shows a decrease in the amounts of cordierite, quartz, and andalusite and an increase in pleonaste and corundum as the contact is approached. Whole rock chemical analyses show a distinct SiO₂ concentration gradient from the wall rocks toward the intrusion; however, the syenite has a higher weight percent SiO₂ than the adjacent schists. It is suggested that silica diffused down an SiO₂ activity gradient into the intrusive; other major oxide components were apparently immobile. The diffusion of silica was probably through intergranular fluids, and the amount of silica available for diffusion was governed by the solubilities of cordierite, andalusite, and quartz in the interstitial fluid.     

Dynamic downscaling of global climate projections for Eastern Europe with a horizontal resolution of 7 km

Climate change is one of the key factors influencing the quantity and quality of water resources in hydrologically sensitive regions. In order to downscale global climate simulations from horizontal resolutions of about 125–200 km to about 7 km, a double nesting strategy was chosen. The modelling approach was implemented with the Regional Climate Model CCLM (COSMO-Climate Local Model) with a first nesting covering a central part of Europe and with a second nesting covering parts of Poland, Belarus, and the Ukraine. A control run—driven by global reanalysis data—was evaluated by comparing the model results with corresponding reference data. Long-term yearly and monthly mean differences of temperature and precipitation were statistically assessed. As reference data for the first nesting, the gridded CRU data set with a horizontal resolution of about 55 km was used. Station data of the NOAA and ECA databases were interpolated to provide an appropriate reference data set for the second nesting. Both nestings overestimated long-term yearly precipitation means. Seasonal evaluation of the first nesting showed positive precipitation biases for spring and winter months and negative biases in summer. Furthermore, differences in the spatial precipitation patterns occured, especially in the high mountain area of the Carpathians. The second nesting overestimated precipitation in spring and summer with smaller biases than in the first nesting. Long-term area means of temperature were properly reproduced. The first nesting showed an overestimation for all months with maximal deviations in summer and spring. In contrast, the second nesting was slightly too warm for summer and autumn and too cold for winter and spring.     

Comparison of oil shales and kerogen concentrates by C nuclear magnetic resonance

Six oil shales and their kerogen concentrates have been studied using ¹³C CP/MAS NMR techniques to study the distribution of organic carbon species. It is found that if the aromatic and aliphatic regions are divided at about 80 or 100 ppm, the apparent aromaticities of a raw shale and its kerogen concentrate are in good agreement. The presence of oxygen-substituted carbons in the raw shales and their depletion in the kerogen concentrates are observed and discussed.     

Otolith Microchemistry Reveals Substantial Use of Freshwater by Southern Flounder in the Northern Gulf of Mexico

Southern flounder Paralichthys lethostigma is a recreationally and commercially important species along the western Atlantic and northern Gulf of Mexico coasts that can exhibit complex early-life habitat-use patterns. Herein, we used an otolith microchemical approach to test the conventional wisdom that juvenile southern flounder spend most of their early life in low-salinity areas of estuaries, focusing on the largely unstudied population in the Mobile-Tensaw Delta, AL. Analysis of strontium/calcium concentrations in otolith cores of age 0 juveniles demonstrated that 68% of these individuals hatched in high-salinity waters before moving into freshwater habitats, with the remaining individuals being spawned in or near freshwater habitat. Further, otolith edge Sr/Ca concentrations revealed that even juveniles used freshwater habitats, particularly during freshwater/oligohaline conditions in our study system. Otolith edge Sr/Ca ratios for fish collected during high-salinity periods differed significantly among collection regions, suggesting seasonal differences in patterns of habitat use between individuals collected upstream (i.e., freshwater habitats) vs. downstream (i.e., euryhaline habitats). These data support the hypothesis that early-life stages of a substantial portion of a coastal southern flounder population use freshwater habitat.     

Comparison of derivative-free optimization methods for groundwater supply and hydraulic capture community problems

Management decisions involving groundwater supply and remediation often rely on optimization techniques to determine an effective strategy. We introduce several derivative-free sampling methods for solving constrained optimization problems that have not yet been considered in this field, and we include a genetic algorithm for completeness. Two well-documented community problems are used for illustration purposes: a groundwater supply problem and a hydraulic capture problem. The community problems were found to be challenging applications due to the objective functions being nonsmooth, nonlinear, and having many local minima. Because the results were found to be sensitive to initial iterates for some methods, guidance is provided in selecting initial iterates for these problems that improve the likelihood of achieving significant reductions in the objective function to be minimized. In addition, we suggest some potentially fruitful areas for future research.     

Reviews

THE PERMAFROST ENVIRONMENT by S. A. Harris. 23 × 14 cm, viii and 275 pages. Croom Helm: London 1986 (ISBN 0 7099 3713 X) $A57.50 (hard).

ENVIRONMENTAL POLICIES: An International Review edited by C. C. Park. 14 × 22 cm, 315 pages. Croom Helm: London 1986 (ISBN 0 7099 2062 8) $A56.25 (hard).

A MODERN DICTIONARY OF GEOGRAPHY by J. Small and M. Witherick. 15 × 23 cm, vi and 233 pages. Edward Arnold: London 1986 (ISBN 0 7131 6434 4) $A28.95 (soft).

PROGRESS IN POLITICAL GEOGRAPHY edited by M. Pacione. 14 × 22 cm, 275 pages. Croom Helm: London 1985 (ISBN 0 7099 2087 3) $A56.25 (hard).

THE PRICE OF WAR: Urbanization in Vietnam 1954–1985, by N. Thrift and D. Forbes. 14 × 22 cm, xiv and 188 pages. Allen & Unwin: London 1986 (ISBN 0 04 3012108) $A59.95 (hard).

INDUSTRIALISATION AND LABOUR FORCE PROCESSES: A Case Study of Peninsular Malaysia (Research Papers on Development in East Java and West Malaysia No. 1) by T. G. McGee and seven others. 17 × 24 cm, xviii and 244 pages. Research School of Pacific Studies, Australian National University: Canberra 1986 (ISBN 0 86784 991 6) $A15.00 plus postage and packing (soft).

CITIES OF THE WORLD: A Compilation of Current Information on Cultural, Geographical, and Political Conditions in the Countries and Cities of Six Continents. Based on the Department of State's ‘Post Reports’ (second edition) edited by M. W. Young and S. L. Stetler. 16 × 23 cm, 3,056 pages in 4 volumes. Gale Research Company: Detroit 1985 (ISBN 0 8103 2059 2) $US235.00 (hard). Supplement 758 pages. 1986 (ISBN 0 8103 1110 0) $US84.00 (hard).