Isotopic variation in the Tuolumne Intrusive Suite,central Sierra Nevada,California     

R. W. Kistler  B. W. Chappell  D. L. Peck  P. C. Bateman 《Contributions to Mineralogy and Petrology》1986,94(2):205-220

Granitoid rocks of the compositionally zoned Late Cretaceous Toulumne Intrusive Suite in the central Sierra Nevada, California, have initial⁸⁷Sr/⁸⁶Sr values (Sri) and¹⁴³Nd/¹⁴⁴Nd values (Ndi) that vary from 0.7057 to 0.7067 and from 0.51239 to 0.51211 respectively. The observed variation of both Sri and Ndi and of chemical composition in rocks of the suite cannot be due to crystal fractionation of magma solely under closed system conditons. The largest variation in chemistry, Ndi, and Sri is present in the outer-most equigranular units of the Tuolumne Intrusive Suite. Sri varies positively with SiO₂, Na₂O, K₂O, and Rb concentrations, and negatively with Ndi, Al₂O₃, Fe₂O₃, MgO, FeO, CaO, MnO, P₂O₅, TiO₂, and Sr concentrations. This covariation of Sri, Ndi and chemistry can be modeled by a process of simple mixing of basaltic and granitic magmas having weight percent SiO₂ of 48.0 and 73.3 respectively. Isotopic characteristic of the mafic magma are Sri=0.7047, Ndi=0.51269 and ¹⁸O=6.0, and of the felsic magma are Sri=0.7068, Ndi=0.51212 and ¹⁸O=8.9. The rocks sampled contain from 50 to 80% of the felsic component. An aplite in the outer equigranular unit of the Tuolumne Intrusive Suite apparently was derived by fractional crystallization of plagioclase and hornblende from magma with granudiorite composition that was a product of mixing of the magmas described above. Siliceous magmas derived from the lower crust, having a maximum of 15 percent mantle-derived mafic component, are represented by the inner prophyritic units of the Tuolumne Intrusive Suite.  相似文献   

Free cupric ion concentrations and Cu complexation in selected Swiss lakes and rivers   总被引：1，自引：0，他引：1  

Hanbin Xue  Andrea Oestreich  David Kistler  Laura Sigg 《Aquatic Sciences - Research Across Boundaries》1996,58(1):69-87

[Cu²⁺] and Cu complexation parameters in some selected freshwater systems in Switzerland were determined by the technique of ligand-exchange and DPCSV. Results from the water columns of some eutrophic and oligotrophic lakes are presented and compared to small acid lakes. Cu is strongly complexed by organic ligands which with very high stability constants at low concentrations are probably biologically produced, as indicated by the seasonal variations in the eutrophic lakes and by the relationship between Cu complexation and algal activity in the eutrophic (pCu=15–16), oligotrophic (pCu=13–14) and acidic (pCu=9–10) lakes. The extent of Cu complexation in river waters was generally lower than in the eutrophic lakes, at similar DOC levels. No obvious correlation between Cu complexation and DOC was observed, indicating that Cu complexing ligands are specific organic compounds.  相似文献   

Size Fractionation (Dissolved, Colloidal and Particulate) of Trace Metals in the Thur River, Switzerland     

Laura Sigg  Hanbin Xue  David Kistler  René Sshönenberger 《Aquatic Geochemistry》2000,6(4):413-434

The distribution of some trace metals (Cu, Zn, Ni, Co,Fe, Mn) and of DOC over a particulate (> 1 m),a colloidal (size < 0.45 m and molecular weight > 10 kD) and an ultrafiltered fraction (< 10 kD)was determined at several sites on the Thur River,Switzerland, at various times of the year. Thecomplexation of Cu by strong ligands in theultrafiltrate and in the conventional filtrate (<0.45 m) was compared using a ligand-exchange/CSV method.The <0.45 m concentrations of Cu (from anaverage of 7 nM to 24 nM), Zn (<5–23 nM), Ni (5–13 nM),Co (1.5–3 nM) and Mn (7–92 nM)increased downstream. The major part of Cu, Zn, Niand Co usually occurred in the ultrafiltratefraction at all sites, whereas Fe and Mn were mostlyin the particulate fraction, under conditions of lowsuspended matter content (< 10 mg L^-1) in theriver. The percentage of metal in the colloidalfraction, with respect to the 0.45-m filtrate,decreased in the order: Cu (median 11%) > Zn Ni(median 5–6%) > Mn Co (median < 5%). DOCalso consisted mostly of molecules in the < 10 kDrange.Cu was strongly complexed by natural organic ligandsin all filtrate and ultrafiltrate samples. A largepart of the strong Cu binding ligands consisted ofcompounds in the < 10 kD range, but colloidalligands with similar properties also occurred. Cu wasdistributed among the dissolved and the colloidalligands, roughly in proportion to organic carbon.The colloidal fraction (as defined here) did notincrease in its proportional amount downstream and wasonly of limited significance in transporting traceelements in the Thur River under low discharge conditions.  相似文献   

Colloidal Stability and Toxicity of Gold Nanoparticles and Gold Chloride on <Emphasis Type="Italic">Chlamydomonas reinhardtii</Emphasis>     

Renata Behra  Bettina Wagner  Linn Sgier  David Kistler 《Aquatic Geochemistry》2015,21(2-4):331-342

Here we have examined interactions of gold nanoparticles differing in primary particle size and coating with the green algae Chlamydomonas reinhardtii as function of the colloidal stability of the particles in the experimental media used for toxicity studies. Interactions of dissolved Au³⁺ ions with algae were also examined. Included endpoints were photosynthetic yield and algal growth. Morphological and structural effects were examined microscopically and by flow cytometry. The results indicate no significant toxicity of gold nanoparticles to C. reinhardtii. Analysis of published data suggests toxicity of gold nanoparticles on algal growth to relate rather to particular coatings than to the gold core.  相似文献   

In Situ Observations of Solar Wind Stream Interface Evolution     

K. D. C. Simunac  L. M. Kistler  A. B. Galvin  M. A. Lee  M. A. Popecki  C. Farrugia  E. Moebius  L. M. Blush  P. Bochsler  P. Wurz  B. Klecker  R. F. Wimmer-Schweingruber  B. Thompson  J. G. Luhmann  C. T. Russell  R. A. Howard 《Solar physics》2009,259(1-2):323-344

The heliocentric orbits of the two STEREO satellites are similar in radius and ecliptic latitude, with separation in longitude increasing by about 45° per year. This arrangement provides a unique opportunity to study the evolution of stream interfaces near 1 AU over time scales of hours to a few days, much less than the period of a Carrington rotation. Assuming nonevolving solar wind sources that corotate with the Sun, we calculated the expected time and longitude of arrival of stream interfaces at the Ahead observatory based on the in situ solar wind speeds measured at the Behind observatory. We find agreement to within 5° between the expected and actual arrival longitude until the spacecraft are separated by more than 20° in heliocentric inertial longitude. This corresponds to about one day between the measurement times. Much larger deviations, up to 25° in longitude, are observed after 20° separation. Some of the deviations can be explained by a latitude difference between the spacecraft, but other deviations most likely result from evolution of the source region. Both remote and in situ measurements show that changes at the source boundary can occur on a time scale much shorter than one solar rotation. In 32 of 41 cases, the interface was observed earlier than expected at STEREO/Ahead.  相似文献   

The Heliospheric Plasma Sheet Observed in situ by Three Spacecraft over Four Solar Rotations     

Simunac  K. D. C.  Galvin  A. B.  Farrugia  C. J.  Kistler  L. M.  Kucharek  H.  Lavraud  B.  Liu  Y. C.-M.  Luhmann  J. G.  Ogilvie  K. W.  Opitz  A.  Popecki  M. A.  Sauvaud  J.-A.  Wang  S. 《Solar physics》2012,281(1):423-447

Solar Physics - In this paper we present in&nbsp;situ observations of the heliospheric plasma sheet (HPS) from STEREO-A, Wind, and STEREO-B over four solar rotations in the declining phase of...  相似文献   

Testing electric field models using ring current ion energy spectra from the Equator-S ion composition (ESIC) instrument     

L. M. Kistler  B. Klecker  V. K. Jordanova  E. Möbius  M. A. Popecki  D. Patel  J. A. Sauvaud  H. Rème  A. M. Di Lellis  A. Korth  M. McCarthy  R. Cerulli  M. B. Bavassano Cattaneo  L. Eliasson  C. W. Carlson  G. K. Parks  G. Paschmann  W. Baumjohann  G. Haerendel 《Annales Geophysicae》1999,17(12):1611-1621

During the main and early recovery phase of a geomagnetic storm on February 18, 1998, the Equator-S ion composition instrument (ESIC) observed spectral features which typically represent the differences in loss along the drift path in the energy range (5–15 keV/e) where the drift changes from being E × B dominated to being gradient and curvature drift dominated. We compare the expected energy spectra modeled using a Volland-Stern electric field and a Weimer electric field, assuming charge exchange along the drift path, with the observed energy spectra for H⁺ and O⁺. We find that using the Weimer electric field gives much better agreement with the spectral features, and with the observed losses. Neither model, however, accurately predicts the energies of the observed minima.  相似文献   

Substorm observations in the early morning sector with Equator-S and Geotail     

R. Nakamura  G. Haerendel  W. Baumjohann  A. Vaivads  H. Kucharek  B. Klecker  E. Georgescu  J. Birn  L. M. Kistler  T. Mukai  S. Kokubun  P. Eglitis  L. A. Frank  J. B. Sigwarth 《Annales Geophysicae》1999,17(12):1602-1610

Data from Equator-S and Geotail are used to study the dynamics of the plasma sheet observed during a substorm with multiple intensifications on 25 April 1998, when both spacecraft were located in the early morning sector (03–04 MLT) at a radial distance of 10–11 R_E. In association with the onset of a poleward expansion of the aurora and the westward electrojet in the premidnight and midnight sector, both satellites in the morning sector observed plasma sheet thinning and changes toward a more tail-like field configuration. During the subsequent poleward expansion in a wider local time sector (20−04 MLT), on the other hand, the magnetic field configuration at both satellites changed into a more dipolar configuration and both satellites encountered again the hot plasma sheet. High-speed plasma flows with velocities of up to 600 km/s and lasting 2–5 min were observed in the plasma sheet and near its boundary during this plasma sheet expansion. These high-speed flows included significant dawn-dusk flows and had a shear structure. They may have been produced by an induced electric field at the local dipolarization region and/or by an enhanced pressure gradient associated with the injection in the midnight plasma sheet.  相似文献   

Production of gyrating ions from nonlinear wave-particle interaction upstream from the Earth's bow shock: A case study from Cluster-CIS     

C. Mazelle  K. MezianeD. LeQuéau  M. WilberJ.P. Eastwood  H. RèmeJ.A. Sauvaud  J.M. BosquedI. Dandouras  M. McCarthyL.M. Kistler  B. KleckerA. Korth  M.B. Bavassano-CattaneoG. Pallocchia  R. LundinA. Balogh 《Planetary and Space Science》2003,51(12):785-795

  相似文献   

MHD model of magnetosheath flow: comparison with AMPTE/IRM observations on 24 October, 1985     

C. J. Farrugia  H. K. Biernat  N. V. Erkaev  L. M. Kistler  G. Le  C. T. Russell 《Annales Geophysicae》1998,16(5):518-527

We compare numerical results obtained from a steady-state MHD model of solar wind flow past the terrestrial magnetosphere with documented observations made by the AMPTE/IRM spacecraft on 24 October, 1985, during an inbound crossing of the magnetosheath. Observations indicate that steady conditions prevailed during this about 4 hour-long crossing. The magnetic shear at spacecraft entry into the magnetosphere was 15°. A steady density decrease and a concomitant magnetic field pile-up were observed during the 40 min interval just preceding the magnetopause crossing. In this plasma depletion layer (1) the plasma beta dropped to values below unity; (2) the flow speed tangential to the magnetopause was enhanced; and (3) the local magnetic field and velocity vectors became increasingly more orthogonal to each other as the magnetopause was approached (Phan et al., 1994). We model parameter variations along a spacecraft orbit approximating that of AMPTE/IRM, which was at slightly southern GSE latitudes and about 1.5 h postnoon Local Time. We model the magnetopause as a tangential discontinuity, as suggested by the observations, and take as input solar wind parameters those measured by AMPTE/IRM just prior to its bow shock crossing. We find that computed field and plasma profiles across the magnetosheath and plasma depletion layer match all observations closely. Theoretical predictions on stagnation line flow near this low-shear magnetopause are confirmed by the experimental findings. Our theory does not give, and the data on this pass do not show, any localized density enhancements in the inner magnetosheath region just outside the plasma depletion layer.  相似文献