The paper evaluates long-term seasonal variations of the deuterium excess (d-excess = delta(2)H - 8. delta(18)O) in precipitation of stations located north and south of the main ridge of the Austrian Alps. It demonstrates that sub-cloud evaporation during precipitation and continental moisture recycling are local, respectively, regional processes controlling these variations. In general, sub-cloud evaporation decreases and moisture recycling increases the d-excess. Therefore, evaluation of d-excess variations in terms of moisture recycling, the main aim of this paper, includes determination of the effect of sub-cloud evaporation. Since sub-cloud evaporation is governed by saturation deficit and distance between cloud base and the ground, its effect on the d-excess is expected to be lower at mountain than at lowland/valley stations. To determine quantitatively this difference, we examined long-term seasonal d-excess variations measured at three selected mountain and adjoining valley stations. The altitude differences between mountain and valley stations ranged from 470 to 1665 m. Adapting the 'falling water drop' model by Stewart [J. Geophys. Res., 80(9), 1133-1146 (1975).], we estimated that the long-term average of sub-cloud evaporation at the selected mountain stations (altitudes between about 1600 and 2250 m.a.s.l.) is less than 1 % of the precipitation and causes a decrease of the d-excess of less than 2 per thousand. For the selected valley stations, the corresponding evaporated fraction is at maximum 7 % and the difference in d-excess ranges up to 8 per thousand. The estimated d-excess differences have been used to correct the measured long-term d-excess values at the selected stations. Finally, the corresponding fraction of water vapour has been estimated that recycled by evaporation of surface water including soil water from the ground. For the two mountain stations Patscherkofel and Feuerkogel, which are located north of the main ridge of the Alps, the maximum seasonal change of the corrected d-excess (July/August) has been estimated to be between 5 and 6 per thousand, and the corresponding recycled fraction between 2.5-3 % of the local precipitation. It has been found that the estimated recycled fractions are in good agreement with values derived from other approaches.

Three types of recent carbonate precipitates from the River Krka, Croatia, were analysed: (1) bulk tufa from four main cascades in a 34 km long section of the river flow through the Krka National Park; (2) a laminar stromatolite-like incrustation formed in the tunnel of a hydroelectric power plant close to the lowest cascade; and (3) recent precipitates collected on artificial substrates during winter, spring and summer periods. Stable isotope compositions of carbon (d 13 C) and oxygen (d 18 O) in the carbonate and organic carbon (d 13 C org ) were determined and compared with d 18 O of water and d 13 C of dissolved inorganic carbon (DIC). The source of DIC, which provides C for tufa precipitation, was determined from the slope of the line ( (Sayles & Curry, 1988). The d 13 C value of added DIC was )13AE6&, corresponding to the dissolution of CO 2 with d 13 C between )19AE5 and )23AE0& Vienna Pee Dee Belemnite (VPDB). The observed difference between the measured and calculated equilibrium temperature of precipitation of bulk tufa barriers indicates that the higher the water temperature, the larger the error in the estimated temperature of precipitation. This implies that the climatic signals may be valid only in tufas precipitated at lower and relatively stable temperatures. The laminar crust comprising a continuous record of the last 40 years of precipitation shows a consistent trend of increasing d 13 C and decreasing d 18 O. The lack of covariation between d 13 C and d 18 O indicates that precipitation of calcite was not kinetically controlled for either of the elements. d 13 C and d 18 O of precipitates collected on different artificial substrates show that surface characteristics both of substrates and colonizing biota play an important role in C and O isotope fractionation during carbonate precipitation.

[1] Mountains within alpine regions can have a significant influence on the geographic distribution of precipitation and on local-to regional-scale climatic and meteorological conditions. Consequently, the oxygen and hydrogen isotope compositions of precipitation are affected by alpine topography as well. The Austrian Network of Isotopes in Precipitation, one of the oldest and densest networks in the world, is therefore an excellent source of isotope data of the last 30 years for investigating the complex processes governing the isotopic composition of precipitation in alpine regions. Fractionation during phase change processes leads to significant isotopic variation in precipitation. Here we show that the spatial isotopic variability, especially in alpine regions, is to a large extent due to nonequilibrium fractionation. Additionally, we conclude that meteorological conditions prevailing at the sampling site are mainly responsible for the observed seasonal pattern in deuterium excess. These results are validated by stepwise multiple regression as well as by applying an empirical model for deuterium excess, which is an indicator of the differential behavior of D and18 O values in vapor and precipitation. The present results enhance the development of models based on detailed statistical assessment of local climatic conditions to improve the quantitative interpretation of isotope data for paleoclimatology delivered by glacial ice of alpine regions.

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The 13C/12C isotopic ratios of samples of acetic acid of biogenic origin obtained by fermentation and of synthetic ones produced from petroleum were determined. The biogenic products had a higher 13C content than the synthetic ones. The origin of vinegar can be determined on this basis. Biogenic acetic acid possesses a lower "C content in the methyl than in the carboxyl group. This regularity was not observed for synthetic acetic acid. The ''C distribution within the molecule seems to depend on the type of synthetic process applied.