Isotopic compositions of S, N and C in soils and vegetation of three forest types in Québec, Canada     

C. Marty  D. Houle  C. Gagnon  L. Duchesne 《Applied Geochemistry》2011,26(12):2181-2190

The concentrations and the isotopic compositions of S, N and C were studied in soils and in the dominant plant species of three forested watersheds (Québec, Canada) located along a latitudinal and atmospheric deposition gradient. Large increases in S, N and C isotope ratios (up to 3.9‰, 10‰, 2.6‰, respectively) were observed with increasing soil depth at the three watersheds. These increases were accompanied by a strong decrease in elemental concentrations resulting in a strong negative relationship between these two variables. Both S and N concentrations throughout the soil profile and δ³⁴S and δ¹⁵N in the mineral soil appeared to increase with increasing S and N deposition rates and decreasing latitude. A strong positive linear relationship was found between δ³⁴S and δ¹⁵N (R² = 0.72) values and between organic S and N concentrations (R² = 0.96) in soils. The slope of the linear relationship between δ³⁴S and δ¹⁵N (δ³⁴S = f(δ¹⁵N)) indicated that isotopic fractionation was almost 4 times higher for S than for N during transformations that occurred in soil. However, this difference might reflect a higher degree of openness of the S cycle compared to the N cycle rather than an isotope effect per se. Overall, the results suggest that N and S inputs significantly impact the isotope ratios and the concentrations of N and S in the soils, and that S and N were closely associated and subject to similar processes with the same isotopic effects throughout the soil profile. Contrary to most studies, δ³⁴S-SO₄ in stream water of the most northerly site with the lowest S deposition rate was significantly higher than δ³⁴S-SO₄ in atmospheric depositions but similar to the δ³⁴S of the bulk mineral soil. It suggests that the mineral soil actually contributes a large portion of the stream S-SO₄ for this site.  相似文献   

Kimmeridgian (Late Jurassic) ostracods from Highway A16 (NW Switzerland): taxonomy, stratigraphy, ecology, and biogeography     

Ulla Schudack  Michael Schudack  Daniel Marty  Gaël Comment 《Swiss Journal of Geoscience》2013,106(2):371-395

Ostracods are a common microfaunal element of the Kimmeridgian of the Jura Mountains in NW Switzerland. The stratigraphical subdivision within the Kimmeridgian can as clearly be inferred from ostracods as it is the case from the ammonite biozonation. This proves the utiliy of the ostracod biozonation, especially where ammonites are not available or rare. The ostracod-bearing layers of the sequence under study (middle part of the Reuchenette Formation = Banné Member, Courtedoux Member and Lower Virgula Marls) have been deposited in waters with highly brackish to marine salinities (high in the pliohaline range to—predominanttly—brachyhaline according to the Venice System, Oertli 1964). From the base of the section (base of the Banné Member, high brachyhaline in average), salinities slowly decreased, with lowest salinities in the lower dinosaur track levels of Courtedoux Member (high pliohaline on average). They then increased again to higher salinities (high brachyhaline on average) above the upper dinosaur track levels of the Courtedoux Member and the Lower Virgula Marls (lowermost A. eudoxus Zone). These trends perfectly correlate with the increased occurence of ammonites above the upper dinosaur track levels. In terms of Kimmeridgian ostracod palaeobiogeography, the fauna of the NW Swiss Jura Mountains described in this work is most similar to the Aquitan and Paris Basins, a little less to Northern Germany, and even less (with not even half of the species in common) to Southern Germany. The NW Swiss Jura Mountains still belong to a largely boreally influenced “Western and Central European subprovince”, whereas Southern Germany (though located more to the north) was subjected to an enhanced tethyan influence.  相似文献   

RECENT HISTORICAL FLUCTUATIONS OF THE GLACIER DU TAILLON,PYRÉNÉES     

Anne F. Gellatly  Jean M. Grove  Alain Bücher  Richard Latham  Brian W. Whalley 《自然地理学》2013,34(5):399-413

The Taillon Glacier in the French Pyrénées offers one of the most detailed records of recent glacier fluctuations in the region. A comprehensive collection of early maps, paintings, and photographs, together with short-term measurements relating to the ice margins and glacier behavior, have made possible a full reconstruction of the glacier's history since the end of the 19th century. The general pattern of ice-front retreat has been punctuated by a series of significant local readvances, dated 1886–1890, 1906–1911, 1926–1928, 1945, and 1964. The record is compared with the more detailed histories of glaciers from the Alps, and signals a surprising degree of sensitivity for the Taillon Glacier, given its overall size and state of survival. [Key words: Taillon Glacier, Pyrénées, Little Ice Age, glaciology.]  相似文献   

IMPACTS OF URBANIZATION ON SURFACE HYDROLOGY,LITTLE EAGLE CREEK,INDIANA, AND ANALYSIS OF LTHIA MODEL SENSITIVITY TO DATA RESOLUTION     

Matt Grove  Jon Harbor  Bernie Engel  Suresh Muthukrishnan 《自然地理学》2013,34(2):135-153

Land-use change in urbanizing areas can significantly alter the hydrology of a watershed and can have serious impacts on wetland water balances, downstream flooding, and groundwater recharge. Most currently available models used in determining the hydrologic impacts of urbanization are not well suited to long-term hydrologic analysis or are too complex and data intensive for widespread practical application. The Long-Term Hydrologic Impact Assessment (LTHIA) model run on a Geographic Information System (GIS) is a relatively simple, user-friendly model that uses the Curve Number method to estimate changes in surface runoff between different stages of development. Application of the model to a large, rapidly urbanizing watershed near Indianapolis, Indiana, suggests that average annual runoff depths increased by more than 60% from 1973 to 1991, with even greater increases for some individual sub-basins. These results are consistent with runoff changes estimated from historical stream flow data in the watershed. A sensitivity analysis to determine minimum data requirements shows that a precipitation record length of 15 years or more is required to produce consistent results with LTHIA and that the highest possible resolution land-use and soils data should be used. The LTHIA model is now available on the Internet at http://www.ecn.purdue.edu/runoff. [Key words: hydrology, urbanization, modeling, GIS.]  相似文献   

Bathyal polychaete assemblages in the region of the Subtropical Front,Chatham Rise,New Zealand     

P. K. Probert  C. J. Glasby  S. L. Grove  B. L. Paavo 《新西兰海洋与淡水研究杂志》2013,47(5):1121-1135

Abstract

Polychaetes were collected from eight sites across the Chatham Rise (New Zealand) in the region of the Subtropical Front from water depths of c. 2300 m to 350 m. A total of 169 putative species representing 36 families was identified. Spionidae, Paraonidae, Cirratulidae, Syllidae, and Orbiniidae accounted for 50% of all polychaete individuals. Multivariate analysis revealed that three sites at c. 350–453 m water depth on muddy sand (6–7% clay) shared similar faunal and environmental characteristics. Numerical dominants included Lumbrineris sp., P seudeurythoe minuta, Dipolydora cf. socialis, Aglaophamus verrilli, Prionospio lehlersi, Syllinae sp., Monticellina sp., and Cossura sp. Replicates from a single site at c. 750 m depth on the southern flank of the Rise produced a distinct assemblage dominated by Paradoneis, Naineris, Notomastus, Harmothoinae, Prionospio lehlersi, Levinsenia, Aricidea, Kebuita, Paraonella, and ?Leiochrus species. Replicates from greater depths north and south of the Rise presented a greater range of assemblage characteristics and environmental parameters including temperature, dissolved oxygen, median grain size, calcium carbonate (CaCO₃), and total organic matter content. Twenty‐eight taxa were found exclusively below 750 m depths including species of Ampharetinae, Chloeia, Pseudeurythoe, Capitellidae, and Cirratulidae. There was a significant difference in faunal composition between northern and southern flanks of the Rise within depth classes and also between sites at the same depth classes. Faunal density and species diversity appeared highest from the crest to 750 m depth on the southern side. Low species diversity at the deepest sites may be confounded by reduced density.  相似文献   

Assessment of climate change impact on Eastern Washington agriculture   总被引：2，自引：0，他引：2  

Claudio O. Stöckle  Roger L. Nelson  Stewart Higgins  Jay Brunner  Gary Grove  Rick Boydston  Mathew Whiting  Chad Kruger 《Climatic change》2010,102(1-2):77-102

An assessment of the potential impact of climate change and the concurrent increase of atmospheric CO₂ concentration on eastern Washington State agriculture was conducted. Climate projections from four selected general circulation models (GCM) were chosen, and the assessment included the crops with larger economic value for the state (apples, potatoes, and wheat). To evaluate crop performance, a cropping system simulation model (CropSyst) was utilized using historical and future climate sequences. Crops were assumed to receive adequate water (irrigated crops), nutrients, and control of weeds, pests and diseases. Results project that the impact of climate change on eastern Washington agriculture will be generally mild in the short term (i.e., next two decades), but increasingly detrimental with time (potential yield losses reaching 25% for some crops by the end of the century). However, CO₂ elevation is expected to provide significant mitigation, and in fact result in yield gains for some crops. The combination of increased CO₂ and adaptive management may result in yield benefits for all crops. One limitation of the study is that water supply was assumed sufficient for irrigated crops, but other studies suggest that it may decrease in many locations due to climate change.  相似文献   

Palaeogeography and diachronous infill of an ancient deep‐marine foreland basin,Upper Cretaceous Cerro Toro Formation,Magallanes Basin     

Anne Bernhardt  Zane R. Jobe  Marty Grove  Donald R. Lowe 《Basin Research》2012,24(3):269-294

The details of how narrow, orogen‐parallel ocean basins are filled with sediment by large axial submarine channels is important to understand because these depositional systems commonly form in through‐like basins in various tectonic settings. The Magallanes foreland basin is an excellent location to study an orogen‐parallel deep‐marine system. Conglomerate lenses of the Upper Cretaceous Cerro Toro Formation have been previously interpreted to represent the fill of a single submarine channel (4–8 km wide, >100 km long) that funneled coarse detritus southward along the basin axis. This interpretation was based on lithologic correlations. New U/Pb dating of zircons from volcanic ashes and sandstones, coupled with strontium isotope stratigraphy, refine the controls on depositional ages and provenance. Results demonstrate that north‐south oriented conglomerate lenses are contemporaneous within error limits (ca. 84–82 Ma) supporting that they represent parts of an axial channel belt. Channel deposits 20 km west of the axial location are 87–82 Ma in age. These channels are partly contemporaneous with the ones within the axial channel belt, making it likely that they represent feeders to the axial channel system. The northern Cerro Toro Formation spans a Turonian to Campanian interval (ca. 90–82 Ma) whereas the formation top, 70 km to the south, is as young as ca. 76 Ma. Kolmogorov–Smirnoff statistical analysis on detrital zircon age distributions shows that the northern uppermost Cerro Toro Formation yields a statistically different age distribution than other samples from the same formation but shows no difference relative to the overlying Tres Pasos Formation. These results suggest the partly coeval deposition of both formations. Integration of previously acquired geochronologic and stratigraphic data with new data show a pronounced southward younging pattern in all four marine formations in the Magallanes Basin. Highly diachronous infilling may be an important depositional pattern for narrow, orogen‐parallel ocean basins.  相似文献   

Xenon in Archean barite: Weak decay of Ba, mass-dependent isotopic fractionation and implication for barite formation     

Magali Pujol  Bernard Marty  Pascal Philippot 《Geochimica et cosmochimica acta》2009,73(22):6834-306

In order to investigate radioactive decay of ¹³⁰Ba and ¹³²Ba which have half-lives on the order 10²⁰-10²¹ a, the isotopic composition of xenon has been measured in 3.5 Ga barite of the Dresser Formation, Pilbara, Western Australia. The analyzed samples were collected at about 86 m depth from a diamond drill core (Pilbara Drilling Project). The fact that the sample has been shielded from modern cosmic ray exposure reduces the number of potentially interfering production pathways, simplifying interpretation of the Xe isotope spectrum. This spectrum is clearly distinct from that of either modern or ancient atmospheric Xe. A strong excess of ¹³⁰Xe is identified, as well as other isotopic excursions which are attributed to mass-dependent isotopic fractionation and contributions from products of uranium fission. The mass-dependent fractionation, estimated at 2.1 ± 0.3% amu⁻¹, can be accounted for by mutual diffusion and Rayleigh distillation during barite formation that is consistent with geological constraints. After correction for mass-dependent fractionation, the concentrations of fissiogenic Xe isotopes demonstrate that the U-Xe isotope system has remained closed over 3.5 Ga. From the excess of ¹³⁰Xe, the two successive electron capture half life of this isotope is estimated at 6.0 ± 1.1 × 10²⁰ a, which is 3.4 times faster than previously estimated (Meshik et al., 2001). We could not find evidence of ¹³²Ba decay within our Xe isotope spectra.  相似文献   

Laser Ablation (193 nm), Purification and Determination of Very Low Concentrations of Solar Wind Nitrogen Implanted in Targets from the GENESIS Spacecraft     

Laurent Zimmermann  Pete Burnard  Bernard Marty  Fabien Gaboriaud 《Geostandards and Geoanalytical Research》2009,33(2):183-194

The GENESIS space mission recovered ions emitted by the Sun during a 27 month period. In order to extract, purify and determine the very low quantities of solar nitrogen implanted in the GENESIS targets, a new installation was developed and constructed at the CRPG (Nancy, France). It permitted the simultaneous determination of nitrogen and noble gases extracted from the target by laser ablation. The extraction procedure used a 193 nm excimer laser that allowed for surface contamination in the outer 5 nm to be removed, followed by a step that removed 50 nm of the target material, extracting the solar nitrogen and noble gases implanted in the target. Following purification using Ti and Zr getters for noble gases and a Cu-CuO oxidation cycle for N₂, the extracted gases were analysed by static mode (pumps closed) mass spectrometry using electron multiplier and Faraday cup detectors. The nitrogen blanks from the purification section and the static line (30 minutes) were only 0.46 picomole and 0.47 picomole, respectively.  相似文献   

White mica trace element and boron isotope evidence for distinctive infiltration events during exhumation of deeply subducted continental crust     

Natalie E. Sievers  Carrie A. Menold  Marty Grove  Matthew A. Coble 《International Geology Review》2017,59(5-6):621-638

ABSTRACT

Previous study of subducted continental crust within the Luliang Shan terrane in Northwest China has documented metasomatic formation of thick, hydrated phengite + garnet-rich selvages at the interface between mafic eclogite blocks and quartzofeldspathic host gneiss. Whole rock concentrations of Cs and Ba within the selvage are enriched by two orders of magnitude relative to the eclogite blocks and host gneiss. We performed in situ ion microprobe analyses of Li, Be, B, Rb, Sr, Cs and Ba and δ¹¹B of phengite within the Luliang Shane terrane to better constrain the source(s) of the infiltrating fluid. The phengite within the selvage are enriched in Li, Cs and Ba and yield δ¹¹B values between ?30‰ and ?9‰, values that are lower than mantle values. High Ba/Rb, Cs/Rb coupled with low B/Be, B/Li and highly negative δ¹¹B values indicate that the high-pressure fluid that formed the selvage was derived from highly devolatilized rocks within the subduction channel. In contrast, muscovite, which crystallized in the adjacent host gneiss during a subsequent lower pressure phase of fluid infiltration at approximately 0.9 GPa depths, has much lower Li, Cs and Ba relative to the high-pressure phengite. These retrograde muscovite have very high concentrations of B (up to 5500 ppm) and Be (up to 50 ppm) and high (?2 to +8‰) δ¹¹B values that are consistent with crystallization from a fluid derived from shallower and less devolatilized regions of the subduction zone. Additional host gneiss samples, regionally distributed and kilometres away from the studied area lack the B-rich signature and indicate that the late stage fluids were likely localized to the region near the studied traverse.  相似文献