Application of the pyrolysis-carbon isotope method for determining the maturity of kerogen in the Bakken shale     

M.E. Conkright  W.M. Sackett  K.E. Peters 《Organic Geochemistry》1986,10(4-6)

A maturity indexing procedure based on the isotopic difference between the total accumulated methane produced by exhaustive pyrolysis and the kerogen (Δ¹³C) and the mole ratio of methane to kerogen carbon (CMR), has been tested by applying a standardized technique, i.e. exhaustive pyrolysis (600°C for 120 hr) of extracted-powdered samples and measurement of the amounts and isotopic composition of the methane and kerogen carbon, on a suite of 15 Bakken shale samples.A linear relation was found between the carbon mole ratio of pyrolysis-derived methane and total organic carbon and the δ¹³C difference between the pyrolysis-derived methane and total organic carbon (r = −0.79); and between the amount of CH₄ generated from exhaustive pyrolysis and H/C atomic ratios (r = +0.91).  相似文献   

Early life history of the red drum,Sciaenops ocellatus (Pisces: Sciaenidae), in Tampa Bay,Florida     

Kevin M. Peters  Robert H. McMichael 《Estuaries and Coasts》1987,10(2):92-107

The distribution, hatching dates, growth, and food habits of larval and juvenile red drum (Sciaenops ocellatus) in Tampa Bay, Florida, are described. From September 1981 through November 1983, 800 larvae and 7,536 juveniles (98%<100 mm SL) were collected, primarily with plankton nets and bag seines. Analysis of otoliths and length-frequency distributions indicate that spawning took place from mid-August through late November with a major peak during October in 1981 and 1982. Larvae became less abundant, but increased in size, from the mouth to the upper bay, indicating that spawning took place in the bay mouth or nearshore waters. At about 8 mm SL (17 days old) larvae settled out along the bay shore before migrating toward low salinity backwater areas. Juveniles grew to about 55 mm SL by the end of December and 303 mm SL by the end of their first year. Young red drum gradually moved back into the bay with increased size and age. Eighty-five percent of larval stomachs, examined were empty; those with food contained copepods almost exclusively. Fewer than 7% of juvenile stomachs were empty. Small juveniles fed primarily on mysids, amphipods, and shrimp, whereas larger juveniles fed more on crabs and fish. Changes in diet were noted with growth, but few differences were seen among areas or habitat types.  相似文献   

Geochemistry of modern seawater and brines from salt pans: Main components and bromine distribution     

Albert Günter Herrmann  Doris Knake  Jürgen Schneider  Heide Peters 《Contributions to Mineralogy and Petrology》1973,40(1):1-24

Seawater at different stages of evaporation from the salt works of Seovlje near Portoro (Yugoslavia) was analyzed geochemically. The seawater there passes through 20 stages of concentration until the first halite crystallizes. All important parameters were determined at all stages: concentrations of Cl, SO₄, Na, K, Ca, Mg, and Br, temperature, pH, Eh, oxygen content and titration alkalinity. With increasing evaporation calcium carbonate crystallizes first followed by calcium sulphate as gypsum and after these halite. All three components crystallize from supersaturated solutions. The pH of the initial seawater is 8.32; it falls abruptly to 6.65 when the first calcium carbonate precipitates. Eh in the original seawater is +393 mv; negative values were found in the halite crystallization pans, which contain an anaerobic mud as a reducing agent. The oxygen content of the solution decreases parallel to the drop in Eh. In the pans in which NaCl crystallizes Eh is zero. Apparently the mud also adsorbs K, as can be inferred from a change in the Mg/K ratio.The bromine partition between crystallizing halite and the brine in the salt pans of Seovlje is discussed with regard to some genetic problems of marine salt deposits. In the conditions in the salt pans the bromine partition coefficient at the beginning of NaCl crystallization from seawater—expressed as b=wt.-% Br (mineral)/wt.-% Br (solution)—is 0.12 to 0.14 or—expressed as D=Br/Cl(mineral)/Br/Cl(solution)—0.030 to 0.034 at temperatures between 33° C and 42° C. The conclusion is that a Br content of about 60 to 75 ppm is to be expected for the first halite that crystallizes from evaporating seawater.  相似文献   

Geologische Untersuchungen an Sedimenten des indisch-pakistanischen Kontinentalrandes (Arabisches Meer)     

Prof. Dr. W. Schott  Dr. U. von Stackelberg  Dr. F. -J. Eckhardt  Dr. B. Mattiat  J. Peters  Dr. B. Zobel 《International Journal of Earth Sciences》1970,60(1):264-275

Zusammenfassung Mit Sedimentmaterial, das von dem Forschungsschiff Meteor und dem pakistanischen Fischereiforschungskutter Machhera gesammelt wurde, sollten die Ablagerungsbedingungen auf dem Meeresboden des indisch-pakistanischen Kontinentalrandes erfaßt und unter anderem festzustellen versucht werden, wo die Schlammassen des Indus auf dem Meeresboden des Arabischen Meeres wiederzufinden sind (Abb. 1).Enge Beziehungen zwischen den ozeanographischen Verhältnissen im Wasserraum (Chemismus und Strömungen) und der Ausbildung der Sedimente konnten erkannt werden. Rhythmisch gebänderte Sedimente auf dem oberen Kontinentalabhang spiegeln die weitreichenden Auswirkungen des Monsunwechsels wider. Indusmaterial ist bis weit in die Tiefsee zu verfolgen. Die Tonmineralien zeigen von der Küste zur Tiefsee und auch mit zunehmender Teufe in den Sedimentkernen die Tendenz: Detritus (Chlorit, Muskovit, Illit) — Zersatz (Montmorrillonit, mixed layer-Minerale) — Rückbildung (Illit).Die liostratigraphische Bearbeitung, kombiniert mit den Ergebnissen einiger C¹⁴-Datierungen ergibt u. a. Sedimentationsraten bis zu > 50 cm/1000 Jahre am oberen Kontinentalabhang abnehmend auf ca. 1 cm/1000 Jahre im offenen Ozean. Die Faunenzusammensetzung erweist das Vorhandensein eines holozänen Klimaoptimums.Die geochemische Untersuchung der jungen Forenwässer zeigt, daß diese sehr schnell die Zusammensetzung fossiler Formationswässer erreichen können (siehe V.Marchig, i. d. Bd.).

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From the R./V. Meteor and the Pakistan F./V. Machhera sediments from the Indian-Pakistan continental margin have been investigated in order to delineate the facies distribution of the recent deposits. One of several objectives of this study was to find out how far the suspended material of the Indus River is being transported into the Arabian Sea.A close genetic relationship was recognised between the oceanographic conditions of the water masses (chemistry and currents) and the characteristics of the sediments. The activity of the monsoons is reflected by the rhythmic lamination of the sediments of the upper continental slope. The suspended matter from the Indus River can be traced far into the Arabian Sea. The clay minerals show the following tendency from litoral to abyssal regions and from the top of the cores downward: detrital clay minerals (chlorite, muscovite, illite) — degraded clay minerals (montmorillonite, mixed-layer minerals) — re-formational minerals (illite).The biostratigraphic investigation of the sediments combined with several C¹⁴-dates results in sedimentation rates from > 50 cm/1000 years at the upper continental slope decreasing to about 1 cm/1000 years in the open ocean. The faunal composition proves the existence of a climatic optimum during part of the Holocene. The geochemical investigation of the recent pore fluids demonstrates that their composition very soon assumes the characteristics of fossil interstitial waters (cf. V.Marchig, in this vol.). p The results will be published in Meteor-Forschungsergebnisse, Reihe C.

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Résumé La tâche à remplir consista à saisir les conditions de sédimentation au fond de la mer dans la zone bordière du talus continental indo-pakistanais en se servant des échantillons de sédimentation recueillis par le navire d'exploration «Meteor» et par le cutter de pêche et de recherche scientifique pakistanais «Machhera» et, entre autres, à tenter de déterminer oú les masses de boue de l'Indus se retrouvent sur le fond de la Mer d'Oman.Il fut possible de reconnaître des relations étroites existant entre les conditions océanographiques (chimisme et courants) et la formation des sédiments. Des sédiments rubanés à stratification fine sur le talus continental supérieur reflètent les effets d'alternance des moussons. Il est possible de suivre les sédiments de l'Indus jusqu'à une grande distance dans les profondeurs de l'océan. Avec l'éloignement da la côte et, dans les carottes, avec l'augmentation de la profondeur de prélèvement les minéraux argileux montrent la tendance suivante: «matériel détritique» (chlorite, muscovite, illite) — «matériel de décomposition chimique» (montmorillonite, minéraux de couches mixtes) — «matériel de recombinaison minéralogique» (illite).L'étude biostratigraphique combinée aux résultats de quelques déterminations radiométriques au¹⁴C donne, entre autres, des taux de sédimentation jusqu'à > 50 cm/1.000 ans au talus continental supérieur — taux qui vont décroissant jusqu'à environ 1 cm/1.000 ans en plein océan. La composition faunique prouve l'existence d'une phase climatique optimum à l'Holocène.L'analyse géochimique des eaux interstitielles récentes montre que cellesci peuvent atteindre, dans uns délai assez bref, la composition des eaux fossiles. (V.Marchig, en ce tome).La publication des résultats est prévue dans les «Meteor» Forschungsergebnisse, Ser. C.

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Meteor Machhera - . — ( ) . . . — C¹⁴ > 50 /1000 , 1 /1000 . . — , .

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The solvus in the system MnCO3-CaCO3     

Christian de Capitani  Tjerk Peters 《Contributions to Mineralogy and Petrology》1981,76(4):394-400

The solvus on the Mn-rich side in the system MnCO₃-CaCO₃ was studied experimentally at 10 kb and lower pressures. The critical point lies at 540 °C and Mn_0.68Ca_0.32CO₃. Reaction rates of demising are extremely sluggish. X-ray calibration curves for (Mn, Ca)CO₃ solid solutions are given. Depicting microprobe analyses of about 300 carbonates from manganese calc silicate marbles affected by different degrees of metamorphism confirm the experimentally derived solvus.Margules parameters were derived from the experimental solvus, giving for spinodal unmixing W _a=20.1+0.032·T and W _b=18.3-0.0033·T, and for binodal unmixing W _a=–22.9+0.035 ·T and W _b=3.36+0.0147·T (All W, in kJ/-mol)A physical interpretation of the Margules parameters based on deformations of the ionic radii in the solid solution is presented. The Margules parameters obtained by this model agree fairly well with the experimental data.  相似文献   

Delineating generalized species boundaries from species distribution data and a species distribution model     

Matthew P. Peters  Stephen N. Matthews  Louis R. Iverson  Anantha M. Prasad 《International journal of geographical information science》2014,28(8):1547-1560

Species distribution models (SDM) are commonly used to provide information about species ranges or extents, and often are intended to represent the entire area of potential occupancy or suitable habitat in which individuals occur. While SDMs can provide results over various geographic extents, they normally operate within a grid and cannot delimit distinct, smooth boundaries. Additionally, there are instances where a zone of primary occupancy (i.e., a mostly continuous region where species exists, excluding outliers) is better suited for particular analyses, such as when examining source/sink population dynamics or modeling movement into new habitats. We present a semi-automated method to delineate a generalized species boundary (GSB) from SDM output, which provides a practical alternative to digitizing. This preliminary boundary is then manually updated based on inventory data and historical ranges. We used the method to generate contemporary boundaries for 132 tree species of the eastern United States, which are complementary to the ranges generated by Elbert Little for North America during the 1970s, but are not replacements. The methods we present can broadly be applied to other grid-based SDM to generate GSBs.  相似文献   

Saint-Pierre-le-Viger (L5-6) from asteroid 2023 CX1 recovered in the Normandy,France—220 years after the historic fall of L'Aigle (L6 breccia) in the neighborhood     

Addi Bischoff  Markus Patzek  Tommaso Di Rocco  Andreas Pack  Aleksandra Stojic  Jasper Berndt  Stefan Peters 《Meteoritics & planetary science》2023,58(10):1385-1398

On February 13, 2023, a huge fireball was visible over Western Europe (fireball event 2023 CX₁). After the possible strewn field was calculated, the first of several recovered samples, with a mass of about 100 g, was discovered just 2 days after the fireball event on the ground of the village of Saint-Pierre-le-Viger. Meanwhile, more than 60 samples with a total mass of more than 1 kg were recovered and a piece of one of these is studied here. The fall occurred 220 years after the historic meteorite fall of L'Aigle on April 26, 1803, <120 km south. L'Aigle is the closest meteorite fall to Saint-Pierre-le-Viger and belongs to the same chondrite group. Both meteorites are breccias containing only clasts of high metamorphic degree (type 5 and type 6). Since only 20% of the L chondrites are breccias this coincidence is remarkable. As just mentioned, both samples studied from these rocks in this work are ordinary chondrite breccias and consist of equilibrated and recrystallized lithologies of petrologic type 6. The brecciated texture in L'Aigle, resulting in a remarkable light–dark structure, is more pronounced than the brecciated features in Saint-Pierre-le-Viger, from which also type 5 fragments have been reported. The compositions of low-Ca pyroxene and olivine grains in Saint-Pierre-le-Viger (Fs_21.2 and Fa_23.4, respectively) clearly require an L-group classification. L'Aigle was classified as an L6 breccia in the past, and this has now been confirmed by new data on low-Ca pyroxene and olivine (Fs_20.7 and Fa_23.8, respectively). Saint-Pierre-le-Viger contains local thin shock veins, and both meteorites are moderately shocked. Most olivines in the studied samples have planar fractures, but the estimated abundance of mosaicized olivines of 30%–40% among the large grains require a S4 shock classification. Oxygen isotope and bulk chemical data of Saint-Pierre-le-Viger certainly support the L chondrite classification. Bulk spectral data of Saint-Pierre-le-Viger are dominated by silicate minerals, that is, Fe-bearing low-Ca pyroxene, olivine, and plagioclase. Isotopic, chemical, and spectral data of the L'Aigle meteorite are shown for comparison and are very similar, providing additional circumstantial evidence of Saint-Pierre-le-Viger's L chondritic nature.  相似文献   

PCR‐based techniques to determine diet of the Australian sea lion (Neophoca cinerea): a comparison with morphological analysis          下载免费PDF全文

Kristian J. Peters  Kathy Ophelkeller    Herdina  Nathan J. Bott  Simon D. Goldsworthy 《Marine Ecology》2015,36(4):1428-1439

Comprehensive dietary information for the endangered Australian sea lion (Neophoca cinerea) is currently limited by the deficiency and poor quality of identifiable prey remains recovered from regurgitate and faeces and the difficulty of observing feeding in the wild. In this study, we investigated DNA‐based prey detection methods using conventional (end‐point) and quantitative real‐time PCR (qPCR) on faeces collected from two captive Australian sea lions fed experimental diets of whole teleost fish, squid and shark tissue. PCR prey detection methods using the mitochondrial cytochrome oxidase subunit I (COI) and 16S genes combined with clone sequencing were compared with prey identified using traditional hard part analysis. The molecular results indicated that prey DNA was degraded. However, prey amplification was successful by targeting short (71 bp) DNA fragments. Both conventional PCR and qPCR techniques significantly increased prey detection compared with analysis of hard parts. For both sea lions, the hard part analysis was constrained by sporadic and extremely low recovery of fish otoliths (<2%), and cephalopod beaks were not recovered from the 116 squid fed. Comparisons between PCR techniques indicated comparable prey detection frequencies for all species tested; however, the sensitivity and greater resolution of qPCR improved prey detection by ~25% in one sea lion fed the experimental squid and perch. The detection of squid DNA ≤ 6 day post‐ingestion by qPCR further exhibits the ability and potential of this method to detect low concentrations of infrequent or pulse prey. This study highlights the use of DNA‐based analysis to detect prey taxa in the absence of identifiable hard prey remains.  相似文献   

Affluence drives the global displacement of land use   总被引：2，自引：0，他引：2  

Jan Weinzettel  Edgar G. Hertwich  Glen P. Peters  Kjartan Steen-Olsen  Alessandro Galli 《Global Environmental Change》2013,23(2):433-438

Increasing affluence is often postulated as a main driver for the human footprint on biologically productive areas, identified among the main causes of biodiversity loss, but causal relationships are obscured by international trade. Here, we trace the use of land and ocean area through international supply chains to final consumption, modeling agricultural, food, and forestry products on a high level of resolution while also including the land requirements of manufactured goods and services. In 2004, high-income countries required more biologically productive land per capita than low-income countries, but this connection could only be identified when land used to produce internationally traded products was taken into account, because higher-income countries tend to displace a larger fraction of land use. The equivalent land and ocean area footprint of nations increased by a third for each doubling of income, with all variables analyzed on a per capita basis. This increase came largely from imports, which increased proportionally to income. Export depended mostly on the capacity of countries to produce useful biomass, the biocapacity. Our analysis clearly shows that countries with a high biocapacity per capita tend to spare more land for nature. Biocapacity per capita can be increased through more intensive production or by reducing population density. The net displacement of land use from high-income to low-income countries amounted to 6% of the global land demand, even though high-income countries had more land available per capita than low-income countries. In particular, Europe and Japan placed high pressure on ecosystems in lower-income countries.  相似文献   

Drivers of change in Brazil’s carbon dioxide emissions     

Manfred Lenzen  Roberto Schaeffer  Jonas Karstensen  Glen P. Peters 《Climatic change》2013,121(4):815-824

Brazil’s economic development has been underpinned by a diverse and – in a global comparison – unusual set of energy carriers, notably hydroelectricity and ethanol from sugar cane. Its energy mix makes Brazil one of the least energy-related carbon-intensive economies worldwide. Given that the country is fast becoming one of the world’s economic powerhouses, decision-makers need to understand the drivers underlying past and current carbon dioxide emissions trends. We therefore investigate a) which key long-term drivers have led to Brazil’s unique emissions profile, and b) the implications of these drivers for Brazil’s national policies. We show that Brazil’s emissions are growing mainly due to increasing individual standards of living, exports and population size, and that this growth is so far unchallenged by technological and structural improvements toward lower emissions intensities and more efficient production structures. As these trends are likely to continue amidst growing international pressure on key economies to reduce their carbon emissions, a decoupling of drivers from emissions is needed to simultaneously meet development and environmental goals.  相似文献