摘要:

The GC-C-IRMS technique represents a new and useful tool to study the15N abundance in amino acids for metabolic studies. Here we present15N analysis data for 13 human plasma protein amino acids at natural abundance and in slightly enriched samples using GC-C-IRMS analysis of N-pivaloyl-i-propyl esters of amino acids. A mean precision of ± 0.71‰ Δ15N or ±0.77‰ Δ15N was determined for all amino acids analysed at natural abundance values and for the slightly enriched samples (< 100‰ δ15N), respectively. However, for individual amino acids at natural abundance derivatized and injected in duplicate the standard deviation ranged from 0.24 to 1.49‰. The lowest natural15N abundance was found for threonine (about - 5‰ δ15N) and the highest for proline and glutamic acid (about 15‰ δ15N). A standard deviation (SD) range of±0.71 (glutamic acid) to ± 4.35 ‰ δ15N (phenylalanine) (mean SD = ± 1.at δ15N) was obtained in protein amino acids in a group of 7 volunteers at natural abundance level. A single oral [15N2]urea bolus was administreted to one healthy volunteer to demonstrate the feasibility of the GC-C-IRMS technique to trace human nitrogen kinetics in plasma protein amino acids. Small but significant differences in15N abundance were found between amino acids, presumably due to their differential participation in transamination reactions.

ISSN:1025-6016    

DOI:10.1080/10256019708234037

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Carbon and nitrogen stable isotope compositions of organic matter, TOC/TN ratio, and manganese concentration in a sediment core that was collected in northern part of Lake Baikal (VER92ST10-GC2, water depth at 922 m, about 3 m long) were investigated to elucidate the origin of the sedimentary organic matter and its associated environmental factors.

ISSN:1025-6016    

DOI:10.1080/10256019708234038

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Since the 1960s intensive isotope hydrogeological studies have been carried out in the Finne mountain range between Herrengosserstedt in Thuringia and the River Unstrut near Karsdorf in Saxony-Anhalt. The new railway line Erfurt-Leipzig/Halle, a part of the traffic projects German Union - Railway-No. 8-, will cross this area with two tunnels, each of which is 6 km long. The tunnelling of the Middle Bunter rocks on the west side involves the crossing of an area with deep wells used for drinking water supply.

ISSN:1025-6016    

DOI:10.1080/10256019708234039

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

The study is focused on the dolomite-limestone drinking water aquifers in the Boč massif, as well as on the andesite-aquifer containing mineral water in the vicinity of Rogaška Slatina. The catchment area is limited and both drinking and mineral waters are discharged from the same source. The increasing use of deeper aquifers means that natural springs and shallow wells have become sporadic. Consequently new techniques of investigating recharge and aquifer capacity are required which can augment classical hydrogeological methods.

ISSN:1025-6016    

DOI:10.1080/10256019708234040

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

An example is presented for the application of groundwater age dating by tritium and chlorofluorocarbon (CFC) measurements to assess water protection zones. The investigation area is located in a rural area close to Osnabrück (Lower Saxony, Germany). Samples from 13 drinking water supply wells were collected in November 1995.

ISSN:1025-6016    

DOI:10.1080/10256019708234041

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

This research deals with pollution impact on natural water resources in the industrial area of Belchatów, central Poland, where a large brown coal deposit is exploited and the coal is burned in an electric power plant. To trace the sources of groundwater pollutants the stable isotope analysis of oxygen and sulfur in sulfates was applied. The mass-spectrometric analysis was performed on SO42-samples from numerous wells and piezometres in the excavation area. By repetitive sampling performed in November 1994, May 1995 and December 1996 significant changes of SO42-concentration and sulfur and oxygen isotopic ratios in several sites were recorded. The interpretation of isotope ratios allowed us to recognize three groups of sulfates: (1) from the leaching of Permian salt dome, (2) produced by the leaching of soluble sulfates from an ash pool and (3) produced by oxidation of natural sulfides in water-bearing rocks.

ISSN:1025-6016    

DOI:10.1080/10256019708234042

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Using different algea types the bioaccumulation of UO22+and Th4+ions from experimental residual wastes of nuclear facilities was investivated. The retaining degree of these ions on microbiological sorbents decreases as:Scenedesmus quadricauda>Porphyridium cruentum>Spirulina platensis>Calothrix sp.2>Calothrix sp.1for UO22+andPorphyridium cruentum>Spirulina platensis>Scenedesmus quadricauda for Th4+. For the same algae it was observed that the retaining degree is much higher for UO22+than for Th4+, probably due to the different linking degrees of hydrolysed species of these ions on the macromolecular compounds of the living cells through the chemical functional groups.

ISSN:1025-6016    

DOI:10.1080/10256019708234043

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Guidelines for Agricultural Countermeasures Following an Accidental Release of Radionuclides. (TECHNICAL REPORTS SERIES No. 363, IAEA Vienna, 1994, 115 pp.)

ISSN:1025-6016    

DOI:10.1080/10256019708234044

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

This is a scanned image of the original Editorial Board page(s) for this issue.

ISSN:1025-6016    

DOI:10.1080/10256019708234036

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor