Insights from the Paleogene tropical Pacific: Foraminiferal stable isotope and elemental results from Site 1209, Shatsky Rise

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/94995/1/palo1207.pd

Isotopic, geophysical and biogeochemical investigation of submarine groundwater discharge : IAEA-UNESCO intercomparison exercise at Mauritius Island

Author Posting. © The Author(s), 2011. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Journal of Environmental Radioactivity 104 (2012): 24-45, doi:10.1016/j.jenvrad.2011.09.009.Submarine groundwater discharge (SGD) into a shallow lagoon on the west coast of Mauritius Island (Flic-en-Flac) was investigated using radioactive (3H, 222Rn, 223Ra, 224Ra, 226Ra, 228Ra) and stable (2H, 18O) isotopes and nutrients. SGD intercomparison exercises were carried out to validate the various approaches used to measure SGD including radium and radon measurements, seepage-rate measurements using manual and automated meters, sediment bulk conductivity and salinity surveys. SGD measurements using benthic chambers placed on the floor of the Flic-en-Flac Lagoon showed discharge rates up to 500 cm/day. Large variability in SGD was observed over distances of a few meters, which were attributed to different geomorphological features. Deployments of automated seepage meters captured the spatial and temporal variability of SGD with a mean seepage rate of 10 cm/day. The stable isotopic composition of submarine waters was characterized by significant variability and heavy isotope enrichment and was used to predict the contribution of fresh terrestrially derived groundwater to SGD (range from a few % to almost 100 %). The integrated SGD flux, estimated from seepage meters placed parallel to the shoreline, was 35 m3/m day, which was in a reasonable agreement with results obtained from hydrologic water balance calculation (26 m3/m day). SGD calculated from the radon inventory method using in situ radon measurements were between 5 and 56 m3/m per day. Low concentrations of radium isotopes observed in the lagoon water reflected the low abundance of U and Th in the basalt that makes up the island. High SGD rates contribute to high nutrients loading to the lagoon, potentially leading to eutrophication. Each of the applied methods yielded unique information about the character and magnitude of SGD. The results of the intercomparison studies have resulted a better understanding of groundwater-seawater interactions in coastal regions. Such information is an important pre-requisite for the protection management of coastal freshwater resources.The financial support provided by the IOC and IHP of UNESCO for travel arrangements, and by the IAEA’s Marine Environment Laboratories for logistics is highly acknowledged. MAC and MEG were supported in part by the US National Science Foundation (OCE-0425061 and OCE-0751525). PPP acknowledges a support provided by the EU Research & Development Operational Program funded by the ERDF (project No. 26240220004), and the Slovak Scientific Agency VEGA (grant No. 1/108/08). The International Atomic Energy Agency is grateful to the Government of the Principality of Monaco for support provided to its Marine Environment Laboratories

Assessment of Renal Function by the Stable Oxygen and Hydrogen Isotopes in Human Blood Plasma

Water (H2O) is the most abundant and important molecule of life. Natural water contains small amount of heavy isotopes. Previously, few animal model studies have shown that the isotopic composition of body water could play important roles in physiology and pathophysiology. Here we study the stable isotopic ratios of hydrogen (δ2H) and oxygen (δ18O) in human blood plasma. The stable isotopic ratio is defined and determined by δsample = [(Rsample/RSTD)−1] * 1000, where R is the molar ratio of rare to abundant, for example, 18O/16O. We observe that the δ2H and the δ18O in human blood plasma are associated with the human renal functions. The water isotope ratios of the δ2H and δ18O in human blood plasma of the control subjects are comparable to those of the diabetes subjects (with healthy kidney), but are statistically higher than those of the end stage renal disease subjects (p<0.001 for both ANOVA and Student's t-test). In addition, our data indicate the existence of the biological homeostasis of water isotopes in all subjects, except the end stage renal disease subjects under the haemodialysis treatment. Furthermore, the unexpected water contents (δ2H and δ18O) in blood plasma of body water may shed light on a novel assessment of renal functions

Hydrologie et géochimie isotopique

On discute certains aspects de la composition isotopique (tritium et isotopes stables) des précipitations mondiales, échantillonnées depuis la fin des années cinquante par le réseau établi par l'Agence internationale de l'énergie atomique de Vienne. Les trois quarts du tritium formé lors des essais thermonucléaires effectués dans l'atmosphère ont été relachés en 1961 et 1962. Les cinq années qui ont suivi correspondent à une période de suspension des essais nucléaires. On assiste alors à une diminution progressive et continue de la teneur en tritium des précipitations, qui permet d'étudier la vélocité de transfert du tritium de la strastophère à la troposphère. La concentration en tritium diminue plus rapidement aux hautes latitudes. Le recyclage des pluies par évapotranspiration, plus intense aux basses latitudes, ainsi que l'injection de tritium stratosphérique par les courants-jet, peuvent expliquer cette différence latitudinale. Dans l'hémisphère nord, le rapport moyen de la concentration en tritium des précipitations entre deux années successives est proche de 0,68 plus ou moins 0,02, à l'exception de l'année 1965, pour laquelle la teneur en tritium a chuté de 50% par rapport à celle de l'année précédente. Entre 30 et 60°N et 30 et 60°S de latitude, les droites de corrélation entre delta 2H et delta 18O des précipitations d'hiver et des précipitations d'été ont des pentes très voisines, mais des interceptions à zéro différentes. La corrélation est : delta 2H = (8,36 plus ou moins 0,13) delta 18O + (14,2 plus ou moins 4,2) en janvier, et delta 2H = (8,33 plus ou moins 0,13) delta 18O + (8,2 plus ou moins 3,9) en juillet. L'excès en deutérium (défini comme d = delta 2H - 8 delta 18O) diffère donc selon les saisons, avec une valeur moyenne de 10,7 plus ou moins 0,6 pour mille en janvier et de 5,8 plus ou moins 0,5 pour mille en juillet... (D'après résumé d'auteur

Carbon isotope exchange rate of DIC in karst groundwater, Chemical Geology

WATER RESSOURCE