Is bigger better? The emergence of big data as a tool for international development policy     

Linnet Taylor  Ralph Schroeder 《GeoJournal》2015,80(4):503-518

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Book review     

Fred W. Schroeder 《Mathematical Geology》1991,23(7):987-989

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Slowing the increase of atmospheric carbon dioxide: A biological approach   总被引：2，自引：0，他引：2  

Paul Schroeder  Lew Ladd 《Climatic change》1991,19(3):283-290

Planting trees to act as carbon sinks has been suggested as a way to slow the increase of atmospheric CO₂. Forestry growth and yield models were used to estimate that it would take 192 million hectares of Douglas-fir (Pseudotsuga menziesii) or 250 million hectares of Loblolly pine (Pinus taeda) to capture and store the United States' anthropogenic carbon emissions for an assumed period of 50 yr, at current emission rates. Although maximum growth rates are similar for both species, Douglas-fir requires less area because of its greater ability to store carbon, and its ability to maintain a high growth rate for a longer period of time. The usefulness of a particular species also depends in part on the length of the planning horizon and the forestry project. For periods of 50 or more years, it is important to consider a species' cumulative carbon storage potential rather than its potential maximum growth rate at some point during its life cycle. Forestation (reforestation and afforestation) appears to be feasible as a possible component of a comprehensive strategy for managing the CO₂ problem, but it must be practiced globally to be effective.The research described in this article has been funded by the U.S. Environmental Protection Agency. This document has been prepared at the EPA Environmental Research Laboratory. in Corvallis, Oregon, through contract number 68-C8-0006 to NSI Technology Inc. It has been subjected to the Agency's peer and administrative review and approved for publication. Mention of trade names or commercial products does not constitute endorsement of recommendation for use.  相似文献   

Diatom assemblages in a reservoir sediment core track land-use changes in the watershed     

Lauren A. Schroeder  Scott C. Martin  G. Jay Kerns  Colleen E. McLean 《Journal of Paleolimnology》2016,55(1):17-33

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SASS measurements of theKu-band radar signature of the ocean     

Schroeder  L. Grantham  W. Mitchell  J. Sweet  J. 《Oceanic Engineering, IEEE Journal of》1982,7(1):3-14

SeaSat-A Satellite Scatterometer (SASS) measurements of normalized radar cross section (NRCS) have been merged with high quality surface-wind fields based on in situ, to create a large data base of NRCS-wind signature data. These data are compared to the existing NRCS-wind model used by the SASS to infer winds. False-color maps of SASS NRCS and ocean winds from multiple orbits show important synoptic trends.  相似文献   

A note on the occurrence of Orbitolina (Orbitolina) sefini Henson, 1948 (Foraminiferida) in the Upper Greensand of S. W. England     

R. Schroeder  M. D. Simmons  M. B. HartC. L. Williams 《Cretaceous Research》1986,7(4)

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Fabrics and sequences of submarine carbonate cements in Holocene Bermuda cup reefs     

Johannes H. Schroeder Ph.D. 《International Journal of Earth Sciences》1972,61(2):708-730

A variety of precipitative synsedimentary CaCO₃ cements lines or fills cavities and surrounds sediment particles within Recent algal cup reefs which dot the rim of the Bermuda platform. These include aragonite needle, spherulitic, and lath cements as well as calcite micrite, palisade, scale, and blocky cements, listed according to respective relative abundances. No distribution pattern of cements is apparent; various combinations of three or four cements are found in almost every sample or thin section. From the occurrence of various cements, factors determining composition and fabric are deduced:

1. Morphology, composition, and coating of the substrate.
2. Direct or indirect influence of organisms such as algae, pelecypods, or crustaceans.
3. Micro-environment, specifically size and permeability, rate of sea-water circulation through the micro-environment, substrates and organisms within the microenvironment.

Various sequences of two or three precipitative cements result from changes in microenvironment; the only cause of such change recognized is the entrance of endolithic algae into partly cemented cavities. This study provides some insight into the origin of submarine cements and a basis for comparative interpretation of cements in fossil marine environments, especially fossil reefs.  相似文献   

Response of resource excavations in Mobile Bay, Alabama, to extreme forcing     

William W. Schroeder  Jean L. W. Cowan  Jonathan R. Pennock  Steve A. Luker  William J. Wiseman 《Estuaries and Coasts》1998,21(4):652-657

Fossil reef deposits of the American oyster,Crassostrea virginica, are a common component of the near surface sediments in the middle and upper reaches of Mobile Bay, northern Gulf of Mexico. Mining of these deposits occurred from 1946 through 1982 in open areas of undisturbed bay bottom, outside of the shipping channel corridors, in water depths of 3–5 m. The mining process resulted in the formation of pit to furrow-shaped depressions with elevated rims at some sites and troughs and ridges in other areas. Studies carried out in the early 1970s predicted normal physical processes would restore the bottom to pre-shell mining conditions within 1 yr, thus minimizing any long-term effects on the Mobile Bay estuary. However, over the period 1974–1976 unfilled excavations, some with raised rims and ridges, were observed where mining had occurred 3–5 yr earlier. In addition, the depressions tended to be sites of relatively high salinity, hypoxic to anoxic water. In 1992–1993, close grid bathymetric surveys produced no indication of either depressions or raised features at any of the old mining sites. Evidence suggests this leveling of the bay’s bathymetry was the result of two major hurricanes, Frederic in 1979 and Elena in 1985, which mobilized and redistributed significant quantities of sediments within Mobile Bay. These findings indicate currents and waves associated with Mobile Bay’s normal tidal activity and annual recurrent storms were acting very slowly to refill depressions and flatten elevated features. In contrast, the direct impact of major hurricanes appears to have served as an effetive agent to return Mobile Bay’s bathymetry to a state similar to pre-shell mining conditions.  相似文献   

Carbonate diagenesis in Quaternary beachrock of Uyombo,Kenya: Sequences of processes and coexistence of heterogenic products     

Prof. Johannes H. Schroeder 《International Journal of Earth Sciences》1979,68(3):894-919

The calcareous quartz sandstone contains a variety of carbonate cements; these and the biogenic carbonate particles have been preserved and altered in various ways.Several inherited submarine intra-particle cements are followed by a submarine high-Mg calcite palisade cement, then by a meteoric low-Mg calcite blocky cement, and finally by a submarine aragonite spherulitic cement. While the sequence of cementation is clearly recognized, the cement assemblage is considerably diversified by various alterations: The palisade cement may be preserved, impoverished in Mg, dissolved, replaced, or neomorphically altered, while the blocky cement may be partially dissolved. As a result of basal dissolution of cement fringes and subsequent cement precipitation in the new pore space the spatial relationship of cements, for example away from a grainsurface, may no more represent the original sequence of cementation, but pretend a more complex diagenetic history.Common carbonate grains are skeletal particles of red and green calcareous algae, molluscs, foraminifers, echinoids, and corals. They are selectively preserved, micritized, dissolved, replaced, or neomorphosed. Preserved and variously altered particles of a given type coexist in outcrop, sample, and thinsection. Even in individual particles original fabric and several alteration products were found. These observations indicate not only gradual or incomplete alteration, but suggest that various alteration processes compete and that micro-environmental parameters play a decisive role in the competition of processes.Using petrographic, chemical, and circumstantial evidence this case history involving sequential, simultaneous, and/or competetive processes is outlined to help interpret other examples of diagenetically complex shallow carbonates.

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Zusammenfassung Der untersuchte kalkige Quarzsandstein, ein quataerer Strandfels, enthält verschiedene Karbonatzemente. Diese wie auch die vorhandenen biogenen Karbonatpartikel sind in verschiedener Weise erhalten oder diagenetisch verändert worden.Vererbten marinen Intrapartikel-Zementen folgt ein mariner Magnesium-Kalzit Palisaden Zement, diesem ein meteorischer magnesiumarmer Kalzit Blockzement und schließlich ein mariner Aragonit Sphaerulit Zement. Diese Zementabfolge ist deutlich zu erkennen, die Zementvergesellschaftung ist jedoch durch die verschiedenen Veränderungen wesentlich vielfältiger geworden. Der Palisaden Zement kann entweder erhalten, Mgverarmt, aufgelöst und danach möglicherweise neomorph oder nach einem Hohlraumstadium ersetzt worden sein; der Blockzement kann teilweise aufgelöst sein. Infolge der partiellen Auflösung von Zementsäumen an der Basis und der nachfolgenden Zementausfällung in dem so entstandenen Hohlraum repräsentiert die räumliche Folge (z. B. von einem Kornrand in die Interpartikelpore hinein) nicht mehr den zeitlichen Ablauf der Zementation, sondern täuscht eine komplexere diagenetische Geschichte vor.Die Karbonatpartikel stammen vorwiegend von kalkigen Rot- und Grünalgen, Mollusken, Foraminiferen, Echinoiden und Korallen. Sie sind selektiv erhalten, mikritisiert, aufgelöst und dann möglicherweise neomorph oder nach Hohlraumstadium ersetzt. Dabei kommen die verschiedenen Erhaltungs- bzw. Veränderungszustände eines bestimmten Partikels nicht nur in einem Aufschluß, sondern auch in einer Probe bzw. einem Dünnschliff nebeneinander vor. Sogar in einem Einzelpartikel werden verschiedene Zustände nebeneinander beobachtet. Diese Beobachtungen zeigen nicht nur, daß die Veränderungen allmählich vor sich gehen, ihr Ablauf also gestört oder unterbrochen werden kann, sondern auch, daß verschiedene Veränderungsprozesse miteinander konkurrieren und daß das Mikromilieu entscheidend beeinflußt, welcher Prozeß wirksam wird.Mit Hilfe petrographischer und chemischer Daten sowie anderer Indizien werden hier in einer Fallstudie eines sehr jungen Gesteins Abfolgen und Konkurrenz diagenetischer Prozesse gezeigt. Dieser Fall soll Verständnis und Interpretation anderer diagenetisch komplexer Flachwasserkarbonate erleichtern.

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Résumé Le grès calcareux étudié contient une variété de ciments carbonatés; ceux-ci et les particules carbonatées d'origine biogénique ont été préservés ou altérés diagéné tiquement de diverses manières.Divers ciments intra-particulaires sous-marines et hérités sont suivis d'abord par un ciment sous-marin palissadique de calcite fortement magnésienne, ensuite par un «blocky cernent» composé de calcite faiblement magnésienne d'origine météorique, et enfin par un ciment sphérulitique aragonitique d'origine sous-marine. Si la succession des phases de sédimentation peut Être clairement connue, l'assemblage des ciments se diversifie considérablement en raison de diverses altérations: le ciment palissadique peut Être préservé bien qu'appauvri en magnésium, remplacé ou altéré par néomorphose tandis que le blocky cement peut Être partiellement dissout. A la suite de dissolution partielle de franges de ciment et de phases de précipitation subséquentes dans les nouvelles porosités ainsi créées, des relations spatiales entre ciments (par exemple en s'éloignant de la surface d'un grain vers l'espace intergranulaire) ne représentent plus les séquences originelles de cimentation mais indiquent une histoire diagénétique plus complexe.Les grains carbonatés plus communs sont des débris bioclastiques d'algues calcaires rouges et vertes, de mollusques, de foraminifères, d'échinoÏdes et de coraux. Ils peuvent Être préservés sélectivement, micritisés, dissous, remplacés ou néomorphosés. Des particules d'un certain type peuvent Être préservées ou au contraire diversement altérées et coexister à l'échelle de l'affleurement, de l'échantillon ou mÊme de la lame mince. MÊme dans les particules individuelles on peut rencontrer cÔte à cÔte les fabrices originelles et divers produits d'altération. Ces observations illustrent non seulement une altération interviennent concurremment et que les paramètres du micro-milieu jouent un rÔle fondamental dans la compétition des processus.

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Decomposition of hydroxy amino acids in foraminiferal tests; kinetics,mechanism and geochronological implications     

Jeffrey L. Bada  Ming-Yung Shou  Eugene H. Man  Roy A. Schroeder 《Earth and Planetary Science Letters》1978,41(1):67-76

The diagenesis of the hydroxy amino acids serine and threonine in foraminiferal tests has been investigated. The decomposition pathways of these amino acids are complex; the principal reactions appear to be dehydration, aldol cleavage and decarboxylation. Stereochemical studies indicate that the α-amino-n-butyric acid (ABA) detected in foraminiferal tests is the end product of threonine dehydration pathway. Decomposition of serine and threonine in foraminiferal tests from two well-dated Caribbean deep-sea cores, P6304-8 and -9, has been found to follow irreversible first-order kinetics. Three empirical equations were derived for the disappearance of serine and threonine and the appearance of ABA. These equations can be used as a new geochronological method for dating foraminiferal tests from other deep-sea sediments. Preliminary results suggest that ages deduced from the ABA kinetics equation are most reliable because “species effect” and contamination problems are not important for this nonbiological amino acid. Because of the variable serine and threonine contents of modern foraminiferal species, it is likely that the accurate age estimates can be obtained from the serine and threonine decomposition equations only if a homogeneous species assemblage or single species sample isolated from mixed natural assemblages is used.  相似文献