Helium transfer from water into quartz crystals: A new approach for porewater dating

Several important fundamental and applied problems require a quantification of slow rates of groundwater flow. To resolve these problems helium appears to be a promising tracer. In this contribution we discuss a new approach, which gives the helium inventory in a rock – pore water system by using the relevant mineral record, i.e., without extraction and investigation of the porewater samples. Some U- and Th-poor minerals such as quartz (quartz separates from Permo-Carboniferous Formation, sandstone–shale interlayering, Molasses Basin, Northern Switzerland, hereafter PCF, are used in this study) contain excessive helium having migrated into their internal helium-accessible volume (HAV) from the surrounding porewater [I.N. Tolstikhin, B.E. Lehmann, H.H. Loosli, A. Gautschi, Helium and argon isotopes in rocks, minerals and related groundwaters: a case study in Northern Switzerland, Geochim. Cosmochim. Acta 60 (1996) 1497–1514]. These volumes are estimated by using helium as a nano-size penetrating tool, i.e., by saturation of the minerals with helium under controlled pressure–temperature conditions and subsequent measurements of the helium-saturated concentrations. In the quartz separates HAV/total volume ratios vary from 0.017% to 0.16%; along with the measured initial (unsaturated) He concentration the HAV gives the internal helium pressure, the mean value obtained for 7 samples (25 sample aliquots) is P=0.45F0.15 atm (1 r). The product of helium pressure and solubility (7.35_10_3 cc STP He/cc H2O for the temperature and salinity of PCF aquifers reported in [F.J. Pearson, W. Balderer, H.H. Loosli, B.E. Lehmann, A. Matter, T. Peters, H. Schmassmann, A. Gautschi, Applied Isotope Hydrogeology–A Case Study in Northern Switzerland, Elsevier Amsterdam, 1991, 439 pp.]) is the mineral-derived He concentration in the respective porewater, CPW=0.0035F0.0017 cc He/cc H2O. This value is in full accord with measured He concentrations in PCF aquifers, CPCF, varying from 0.0045 to 0.0016 cc He/cc H2O. This agreement validates the proposed approach and also shows that the mineral–porewater helium–concentration equilibrium has been established. Indeed, estimates of the He-migration rates through our quartz samples show that in ~6000 years the internal pressure should equilibrate with He-concentration in related porewater of PCF, and this time interval is short compared to independent estimates [I.N. Tolstikhin, B.E. Lehmann, H.H. Loosli, A. Gautschi, Helium and argon isotopes in rocks, minerals and related groundwaters: a case study in Northern Switzerland, Geochim. Cosmochim. Acta 60 (1996) 1497–1514]. The helium inventory in the rock–porewater assemblage shows that helium abundance in pore waters is indeed important. In shale samples (with ~15% porosity) porewaters contain more helium than the host minerals altogether. Porewater heliumconcentration profiles, available from the mineral record, along with helium production rates are input parameters allowing model(s) of helium migration through a hydrological structure to be developed. Quite high helium concentrations in PCF porewaters imply slow removal mechanisms, which will be discussed elsewhere.

Herkunft und Zukunft : 2 Essays zum Schicksal e. Volkes ; mit Bildern von Max Liebermann ... u.a.

von Arnold Zweig

Friedliche Bilder : Novellen u. Erzählungen für die weibliche Jugend

von Rosalie Koch. Mit 8 fein illum. Bildern v. Th. Hosemann

Aufrichtig teutsch redender Hebräer, welcher gründlich zeiget den Ursprung u. die Schicksaale des Jüd. Volcks wie auch Deroselben Kirchenweesen, ... alles aus ihren eigenen u. and Schrifft ... dargethan

auch mit 30 ... Kupf. erl. u. in 4 Haupt. Th. abgefasset von Johann Christian Georg Bodenschatz

Na 50 Nachlass Arthur Schopenhauer - 'Schopenhauer-Archiv', 238 - Zusendung von Zerlang einer mathematischen Abhandlung

u.a.: genetischer und organischer Zusammenhang der Geometrie;

Na 50 Nachlass Arthur Schopenhauer - 'Schopenhauer-Archiv', 230 - Darstellung der gestiegenen Bedeutung der Schopenhauerschen Philosophie in Deutschland

u.a.: Besuch in Frankfurt am Main; Bedeutung der Philosophie Schopenhauers; Rezeption von Parerga und Paralipomena in Berlin; Publikation "Zur Geschichte der neueren Philosophie" von Georg Weigelt (1855); Carl Vogt; Elsner;

Laute {[u.a.] drei Zupfinstrumente, Instrumentendarstellung

Signatur des Originals: S 36/G02592

Christlicher Jugendtempel : ein Gebet- u. Andachts-Buch für die reifere Jugend beiderlei Geschlechts

verf. von Pfarrer Th. Burkart

An investigation of the association between obesity, acanthosis nigricans, and fasting serum insulin level in 6--9 year old children living on the El Paso-Juarez U.S.-Mexico border

The objectives of this study were to investigate the relationship between fasting serum insulin levels and Acanthosis Nigricans (AN) (a dermatological condition characterized by hyperpigmentation and thickening of the skin in specific body areas such as the neck and knuckles) and obesity among 6 to 9 year old children. Children were selected at random from a pediatric clinic located on the U.S.-Mexico border. Because none of the children participants had a weight for height at or above the 97th percentile of the CDC growth charts, obesity was defined as weight for height at or above the 95th percentile and at risk of overweight between the 85 th and 95th percentiles of the CDC growth charts. Anthropometrics, blood samples for fasting serum insulin and blood glucose, and a picture of the neck were obtained at baseline (n = 85) and 6 months later (n = 49). None of the children partipating had high fasting serum insulin levels and only 2 children had AN degree 2 (moderately severe). At baseline children with a weight for height at or above the 95th, percentile had 15 units less of insulin than children who weighed less. However, 6 months later this was not confirmed, thus the baseline result is considered to be an anomaly. Eventhough statistical significance was not reached, results showed that children without AN had 5 percentiles lower weight for height than children with AN. The most important recommendation from this study is the need to monitor longitudinal growth in children to characterize the individual child's growth pattern. AN seems to be related to longitudinal growth changes. ^