Synthesis in Estuarine and Coastal Ecological Research: What Is It,Why Is It Important,and How Do We Teach It?

During the last two decades, there has been growing interest in the integration of existing ideas and data to produce new synthetic models and hypotheses leading to discovery and advancement in estuarine and coastal science. This essay offers an integrated definition of what is meant by synthesis research and discusses its importance for exploiting the rapid expansion of information availability and for addressing increasingly complex environmental problems. Approaches and methods that have been used in published synthetic coastal research are explored and a list of essential steps is developed to provide a foundation for conducting synthetic research. Five categories of methods used widely in coastal synthesis studies are identified: (1) comparative cross-system analysis, (2) analysis of time series data, (3) balance of cross-boundary fluxes, (4) system-specific simulation modeling, and (5) general systems simulation modeling. In addition, diverse examples are used to illustrate how these methods have been applied in previous studies. We discuss the urgent need for developing curricula for classroom and experiential teaching of synthesis in coastal science to undergraduate and graduate students, and we consider the societal importance of synthetic research to support coastal resource management and policy development. Finally, we briefly discuss the crucial challenges for future growth and development of synthetic approaches to estuarine and coastal research.     

Correction: Hydraulic tomography analysis of municipal-well operation data with geology-based groundwater models

Hydrogeology Journal - A Correction to this paper has been published: https://doi.org/10.1007/s10040-021-02351-x     

Hydrogeochemical prospecting for porphyry copper deposits in the tropical-marine climate of Puerto Rico

A hydrogeochemical survey utilizing waters from streams and springs was conducted in the area of two known porphyry copper deposits in the tropical-marine climate of westcentral Puerto Rico. The most important pathfinder for regional hydrogeochemical surveys is sulfate which reflects the associated pyrite mineralization. Because of increased mobility due to intense chemical weathering and the low pH environment, dissolved copper can also be used as a pathfinder for regional surveys and has the advantage of distinguishing barren pyrite from pyrite associated with copper mineralization. For follow-up surveys, the most important pathfinders are copper, sulfate, pH, zinc, and fluoride. High concentrations of dissolved copper and moderate concentrations of sulfate is a diagnostic indication of nearby sources of copper minerals.An understanding of the geochemical processes taking place in the streambeds and the weathering environment, such as the precipitation of secondary copper minerals, contributes to the interpretation of the geochemical data and the selection of the most favorable areas for further exploration.     

Generation of mid-ocean ridge basalts at pressures from 1 to 7 GPa

We propose a model for the generation of average MORBs based on phase relations in the CaO-MgO-Al₂O₃-SiO₂-CO₂ system at pressures from 3 to 7 GPa and in the CaO-MgO-Al₂O₃-SiO₂-Na₂O-FeO (CMASNF) system at pressures from ∼0.9 to 1.5 GPa. The MELT seismic tomography (Forsyth et al., 2000) across the East Pacific Rise shows the largest amount of melt centered at ∼30-km depth and lesser amounts at greater depths. An average mantle adiabat with a model-system potential temperature (T_p) of 1310°C is used that is consistent with this result. In the mantle, additional minor components would lower solidus temperatures ∼50°C, which would lower T_p of the adiabat for average MORBs to ∼1260°C. The model involves generation of carbonatitic melts and melts that are transitional between carbonatite and kimberlite at very small melt fractions (<0.2%) in the low-velocity zone at pressures of ∼2.6 to 7 GPa in the CMAS-CO₂ system, roughly the pressure range of the PREM low-velocity zone. These small-volume, low-viscosity melts are mixed with much larger volumes of basaltic melt generated at the plagioclase-spinel lherzolite transition in the pressure range of ∼0.9 to 1.5 GPa.In this model, solidus phase relations in the pressure range of the plagioclase-spinel lherzolite transition strongly, but not totally, control the major-element characteristics of MORBs. Although the plagioclase-spinel lherzolite transition suppresses isentropic decompression melting in the CMAS system, this effect does not occur in the topologically different and petrologically more realistic CMASNF system. On the basis of the absence of plagioclase from most abyssal peridotites, which are the presumed residues of MORB generation, we calculate melt productivity during polybaric fractional melting in the plagioclase-spinel lherzolite transition interval at exhaustion of plagioclase in the residue. In the CMASN system, these calculations indicate that the total melt productivity is ∼24%, which is adequate to produce the oceanic crust. The residual mineral proportions from this calculation closely match those of average abyssal peridotites.Melts generated in the plagioclase-spinel lherzolite transition are compositionally distinct from all MORB glasses, but do not have a significant fractional crystallization trend controlled by olivine alone. They reach the composition field of erupted MORBs mainly by crystallization of both plagioclase and olivine, with initial crystallization of either one of these phases rapidly joined by the other. This is consistent with phenocryst assemblages and experimental studies of the most primitive MORBs, which do not show an olivine-controlled fractionation trend. The model is most robust for the eastern Pacific, where an adiabat with a T_p of ∼1260°C is supported by the MELT seismic data and where the global inverse correlation of (FeO)₈ with (Na₂O)₈ is weak. Average MORBs worldwide also are well modeled. A heterogeneous mantle consisting of peridotite of varying degrees of major-element depletion combined with phase-equilibrium controls in the plagioclase-spinel lherzolite transition interval would produce the form of the global correlations at a constant T_p, which suggests a modest range of T_p along ridges. Phase-composition data for the CMASNF system are presently not adequate for quantitative calculation of (FeO)₈-(Na₂O)₈-(CaO/Al₂O₃)₈ systematics in terms of this model. The near absence of basalts in the central portion of the Gakkel Ridge suggests a lower bound for T_p along ridges of ∼1240°C, a potential temperature just low enough to miss the solidus for basalt production at ∼0.9 GPa. An upper bound for T_p is poorly constrained, but the complete absence of picritic glasses in Iceland and the global ridge system suggests an upper bound of ∼1400°C. In contrast to some previous models for MORB generation that emphasize large potential temperature variations in a relatively homogeneous peridotitic mantle, our model emphasizes modest potential temperature variations in a peridotitic mantle that shows varying degrees of heterogeneity. Calculations indicate that melt productivity changes from 0 to 24% for a change in T_p from 1240 to 1260°C, effectively producing a rapid increase to full crustal thickness or decrease to none as ridges appear and disappear.     

Zur Stratigraphie,Petrologie und Genese einer Bentonit-Lage aus dem oberen Mittel-Turon (Oberkreide) des südöstlichen Münsterlandes

Zusammenfassung Die Bentonit-Lage kann möglicherweise mit der Lage M₆₈ aus dem Turon von Lüneburg (Norddeutschland) korreliert werden. Identifiziert wurden vulkanische Glasfragmente, Quarz, Na-, K-Feldspat, Oligoklas, Biotit, Muskovit, Calcit, Schwerminerale (u. a. Olivin, Hornblende) und Tonminerale (Kaolinit, Illit, mixed-layer Illit/Smektit, FeBeidellit - z. T. in großen Aggregaten). Die vulkanoklastischen Gläser zeigen alle Übergänge von intakt zu völlig devitriert. Mit Hilfe der Elektronenstrahl-Mikrosonde konnten, bei Berücksichtigung der Kathoden-Lumineszenz, die Feldspäte chemisch analysiert und genetisch in solche mit niedrigerer und solche mit höherer (vulkanoklastisch) Bildungstemperatur gegliedert werden. Von den Schwermineralen dürften vor allem Olivin und Hornblende vulkanogener Herkunft sein. Untersuchungen der durch Umwandlung vulkanischen Materials entstandenen kompakten Smektit-Aggregate mittels Mikrosonde, Röntgendiffraktometrie und Mössbauer-Spektroskopie zeigten, daß es sich hier um ein AI-reiches Glied der Mischungsreihe Nontronit-Beidellit (Fe-reicher Beidellit) handelt. Differentialthermoanalytische Untersuchungen ergaben für Fe-reiche, dioktaedrische, smektitische Tonminerale typische Kurven. Das Ausgangsmaterial des Bentonits war intermediär bis basisch. Äolischer oder kombiniert äolischer und mariner Transport von Exhalationspunkten im mitteleuropäischen Raum werden diskutiert.

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The bentonite can probably be correlated with horizon M₆₈ in the Turonian of Lüneburg in northern Germany. Volcanic glass fragments, quartz, Na and K feldspars, oligoclase, biotite, muscovite, calcite, heavy minerals (i. a. olivine, hornblende) and clay minerals (kaolinite, illite, mixed-layer illite/smectite and Fe-beidellite) were identified. The glass shows a spectrum of all states from unaltered to completely devitrified. Analysis of feldspars by means of electron microprobe and cathodo-luminescence has allowed to divide them into genetically high (pyroclastic) and low temperature forms. Of the heavy minerals, olivine and hornblende most clearly are of volcanic origin. Examinations of smectite aggregates (alteration products of volcanic material) by electron microprobe, x-ray diffractometry, and Mössbauer spectroscopy demonstrated the presence of a member of the continuous series nontronite-beidellite (Fe-rich beidellite). Differential thermal analysis gave typical curves for dioctahedral Fe-rich smectites. The chemical composition of the original material of the bentonite was intermediate to basic. Eolian or eolian and marine current transport from sources in central Europe are considered.

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Résumé La couche de bentonite peut probablement être corrélée avec la couche M₆₈ du Turonien de Lunebourg (au nord de l'Allemagne). Des fragments de verre volcanique, du quartz, du feldspath sodique, du feldspath potassique, de l'oligoclase de la biotite, de la muscovite, de la calcite, des minéraux lourds (p. ex. olivine, hornblende) et des minéraux argileux (kaolinite, illite, mixed-layer illite/smectite, beidellite ferreux — en partie en grands agrégates) ont été identifiés. Les verres pyroclastiques montrent tous les passages du verre intact jusqu'au verre entièrement dévitrifié. A l'aide de la microsonde électronique et en prenant en considération la cathodoluminescence, les feldspaths pouvaient être analysés chimiquement et ordonnés génétiquement selon leur température de formation. Ceux à haute temperature de formation sont pyroclastiques. Parmi les minéraux lourds pouvaient avant tout être d'origine volcanogène, l'olivine et la hornblende. Les études des agrégats de smectites compacts formés par la transformation de matériaux volcaniques montrent grâce à la microsonde, la diffractométrie X et de la spectrométrie de Mössbauer qu'il s'agit dans ce cas là d'un membre riche en Al de la série des mélanges nontronite-beidellite (beidellite ferreux). Des analyses thermiques différentielles donnèrent des courbes typiques pour les minéraux argileux smectitiques, dioctaédriques et riches en Fe. La matière de base de la bentonite était intermédiaire à basique. Transport éolien ou transport combiné, éolien et marin des points d'exhalation dans l'espace européen central seront dicutés.

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上部地壳的流体作用与大理岩的低温塑性

本文应用光学显微镜、透射电子显微镜和阴极发光显微镜系统研究了Ｗａｔｅｒｂｅｒｇ断层带（纳米比亚）内粗晶大理岩中发育的构造岩,宏观碎裂结构与微观糜棱装结构是断层构造岩的主要特点。巨大的孪形碎屑与弥漫的细小粒质形成了鲜明的反差,广泛发育的压溶颖合线与多阶段方解石细脉遍布构造带不同部位,ＴＥＭ亚微粒粒度具有简单的峰值分布（～０．３～０．４μｍ）,但动态重结晶颗粒的粒度却具有较大的变化范围（０．１～３．０     

Complex formation in the ternary system Mg(II)-CO2-H2O

The carbonato and hydrogencarbonato complexes of Mg²⁺ were investigated at 25 and 50° in solutions of the constant ClO₄^? molality (3 M) consisting preponderantly of NaClO₄. The experimental data could be explained assuming the following equilibria: Mg²⁺ + CO_2B + H₂O ag MgHCO⁺₃ + H⁺, $\text{log}{}^1\text{β}{}_1\text{= ?7.64}{}_4\text{± 0.01}{}_7\text{(25°), ?7.46}{}_2\text{± 0.01}{}_1\text{(50°)}$, Mg²⁺ + 2 CO_2g + 2 H₂Oag Mg(HCO₃)⁰₂ ± 2 H⁺, $\text{log}{}^1\text{β}{}_2\text{= ?15.00 ± 0.14 (25°)}$, ?15.37 ± 0.39 (50°), Mg²⁺ + CO_2g + H₂Oag MgCO⁰₃ + 2 H⁺, $\text{log}{}^1\text{k}{}_1\text{= ?15.64 ± 0.06 (25°)}$,?15.23 ± 0.02 (50°), with the assumption γ_MgCO3⁰ = γ_Mg(HCO3)⁰2, ΔG⁰(I = 0) for the reaction MgCO⁰₃ + CO_2g + H₂O = Mg(HCO₃)⁰₂ was estimated to be ?3.9₁ ± 0.8₆ and 0.6 ± 2.4 kJ/mol at 25 and 50°C, respectively. The abundance of carbonate linked Mg(II) species in fresh water systems is discussed.     

Biogeochemistry of Mono Lake,California

Modern sediments of Mono Lake show marked variation in lipid composition with depositional environment. Constituents derived from the drainage basin, characterized by high molecular weight alkane hydrocarbons (C₂₅–C₃₁), and the steroids β-sitosterol and brassicasterol, predominate in near-shore environments. In the deepest part of the lake, sediments exhibit a combination of externally-derived constituents, and lipids derived from the lake biota; the latter characterized by low molecular-weight alkanes and alkenes (C₁₅–C₁₇), phytane, and the steroids ergost-7-en-3β-ol and 24-ethylcholest-7-en-3-β-ol. Steranes, 4-methylsteranes, and the C₁₈ and C₁₉ isoprenoids appear to be forming in the intensely reducing bottom sediments at the present time.The compositions of samples from the Pleistocene succession of Mono Basin suggest that sample-to-sample variation within the same stratum is negligible so long as unweathered samples from the same depositional environment are compared. Sediments having equivalent lithologies may or may not have similar compositions, but sediments having similar fossil contents do show similar lipid compositions. Subaerial weathering of sediments causes a marked decrease in the amount of extractable organic material, as well as distinct changes in its hydrocarbon composition. Specifically, weathered sediments exhibit a decrease in relative content of low molecular weight hydrocarbons and a relative increase in nC₂₂.Organic composition of sediments from the Pleistocene stratigraphie column cannot be correlated with depth of burial. Compositional changes with stratigraphie position are probably related to paleo-ecological factors such as population or productivity rather than depth of burial. Lithology and organic composition provide mutually-corroborating evidence regarding glacial advances in the adjacent Sierra Nevada Mountains. During glaciations, the lake sediments are rich in sandstones, and the organic composition shows a predominance of externally-derived debris, with no evidence for contributions from the lake biota.     

Biomarkers in sedimentary sulfides of precambrian age

Samples of the Mt Isa formation (Australia, c, 1.5 Ga), and the Shungit formation (U.S.S.R., c. 2.3 Ga) were studied by organic geochemical means. All samples were freed of any low-molecular-weight solvent soluble organic material in order to insure the authenticity of the analysed material. The isolation of biochemical compounds entrapped in sulfides was the major goal of this work.Organic compounds that were entrapped during the early stages of sulfide formation may obviously survive extended periods of time and can be released by a mild hydrogenation of the sulfides. Preliminary investigations of the hydrocarbon fraction indicate n-alkanes, monomethylalkanes, cycloalkanes, and an unknown series of branched alkanes as major constituents. Their distribution patterns show great selectivity with respect to structures and chain lengths of individual compounds. Differences between the hydrogenation reaction product and the sample extract may arise from the release of a different kind of lipid material through dissolution of the sulfides.