The present project compared acute hypoxia-induced changes in lactate thresholds (methods according to Mader, Dickhuth and Cheng) with changes in high-intensity endurance performance. Six healthy and well-trained volunteers conducted graded cycle ergometer tests in normoxia and in acute normobaric hypoxia (simulated altitude 3000 m) to determine power output at three lactate thresholds (PMader, PDickhuth, PCheng). Subsequently, participants performed two maximal 30-min cycling time trials in normoxia (test 1 for habituation) and one in normobaric hypoxia to determine mean power output (Pmean). PMader, PDickhuth and PCheng decreased significantly from normoxia to hypoxia by 18.9 ± 9.6%, 18.4 ± 7.3%, and 11.5 ± 6.0%, whereas Pmean decreased by only 8.3 ± 1.6%. Correlation analyses revealed strong and significant correlations between Pmean and PMader (r = 0.935), PDickhuth (r = 0.931) and PCheng (r = 0.977) in normoxia and partly weaker significant correlations between Pmean and PMader (r = 0.941), PDickhuth (r = 0.869) and PCheng (r = 0.887) in hypoxia. PMader and PCheng did not significantly differ from Pmean (p = 0.867 and p = 0.784) in normoxia, whereas this was only the case for PCheng (p = 0.284) in hypoxia. Although investigated in a small and select sample, the results suggest a cautious application of lactate thresholds for exercise intensity prescription in hypoxia.

The Leoganger Steinberge are a heavily karstified massif largely composed of Dachstein dolomite and limestone hosting the deepest through-trip cave in the world, Lamprechtsofen, whose frontal parts are developed as a show cave. Many parts of this 60 km-long and 1724 m-deep system are hydrologically active. 1.5 km behind the lower cave entrance Grüntopf stream and Kneippklamm stream merge to form the main cave stream. Another underground stream, Stainerhallen stream, flows through the eponymous hall of the show cave. Since 2007 water temperature, electrical conductivity and water level have been monitored in the Grüntopf and Kneippklamm stream. Water temperature and water level in the Stainerhallen and main cave stream have been measured since 2016.The long-term dataset (2013–2017) shows that the water temperature of the cave streams (Grüntopf stream: 3.7–5.2°C; Kneippklamm stream: 5.1–5.9°C) is largely invariant, but the electrical conductivity varies strongly (Grüntopf stream: 107–210 µS/cm; Kneippklamm stream: 131–248 µS/cm) in response to snowmelt and precipitation events. The event water of the Kneippklamm stream is characterized by a low electrical conductivity and is then followed by slightly warmer and higher mineralized water derived from the phreatic zone. This dual flow pattern also explains the asymmetrical changes of the water level during snowmelt: the fast event water flows directly through vadose pathways to the measurement site, whereas the hydraulic (phreatic) response is delayed. The Grüntopf stream reacts to precipitation and snowmelt events by changes in the karst-water table, which can be explained by a piston flow-model. The Kneippklamm stream reveals evidence of a lifter system.The altitude of the catchments was calculated using δ18O values of water samples from the underground streams and from surface precipitation. The Grüntopf stream shows the highest mean catchment (2280 m a.s.l.), which is in agreement with its daily fluctuations of the water level until August caused by long-lasting snowmelt. The Stainerhallen stream has the lowest catchment (average 1400 m a.s.l.). The catchments of the other two streams are at intermediate elevations (1770–1920 m a.s.l.). The integration of the catchment analyses and observations from tracer tests conducted in the 1970s showed that the latter reflected only one aspect of the karst water regime in this massif. During times of high recharge the water level rises, new flow paths are activated and the karst watershed shifts.

Abstract Metasomatism is the prime process to create compositional heterogeneity of the upper mantle. Mineralogical and mineral chemical changes of the mantle triggered by metasomatism can be used to deduce the nature of the metasomatic agent(s) and to constrain the timing of metasomatism. This information is vital for an understanding of the secular evolution of a given mantle segment and the magmatic processes occurring therein. For this study spinel-lherzolites and -websterites were collected from ∼16 Myr old alkali-basaltic lava flows that were extruded on the Bolaven Plateau in south–central Laos. These xenoliths are fragments of the shallow continental lithosphere of the SE Asian peninsula and originate from a mantle segment that acted as source for Cenozoic basaltic volcanism in the wake of the India–Asia collision. In both rock types modal metasomatism formed apatite ± whitlockite ± phlogopite ± calcic amphibole ± calcite ± orthopyroxene. The principal metasomatic phase is apatite, which appears in three varieties. Type-I apatite is ±inclusion-free and associated with phlogopite, calcic amphibole, calcite and lamellar orthopyroxene. It is high in Na and low in P and shows low analytical totals indicating a type-B carbonate–apatite component. Type-I apatite presumably precipitated from a P-alkali-rich mixed H2O–CO2 fluid with low large ion lithophile element (LILE)–light rare earth element (LREE) contents. Type-II apatite shows a spongy texture and has lower Na and higher P contents with higher analytical totals. Crosscutting discontinuous zones of type-II characteristics within type-I apatites indicate type-II formation through an exchange Na+ + CO32– = PO43– + Ca2+ by a later fluid with lower aCO2. REE-rich type-III apatite is the youngest type and formed by infiltration of basaltic melts as part of spongy rims around clinopyroxene. One lherzolite contains whitlockite in addition to apatite. Whitlockite formation is ascribed to a short-lived metasomatic event involving a fluid with extremely low aH2O. Disequilibrium between whitlockite and the bulk assemblage is indicated by hydrous silicates in the immediate vicinity of whitlockite and by substantial H2O contents of 250–370 µg g–1 in clinopyroxenes and 170–190 µg g–1 in orthopyroxenes. High-density (1·15–≥1·17 g m–3) CO2–fluid inclusions in the whitlockite-bearing sample provide evidence for the presence of low-aH2O fluids at mantle depths. The spinel-herzolites may also show cryptic metasomatism evidenced by P zoning in olivine, which is characterized by P-poor (<20–130 µg g–1) cores and P-rich (170–507 µg g–1) rims, the latter in part with oscillatory zoning on a µm scale. Element correlations indicate [4]Si4+ + [6](Mg, Fe)2+ = [4]P5+ + [6]Li+, 2 [4]Si4+ + 4 [6](Mg, Fe)2+ = 2 [4]P5+ + 3 [6](Mg, Fe)2+ + [6]vac and/or 5 [4]Si4+ = 4 [4]P5+ + [4]vac as major P incorporation mechanisms. High P–T experiments conducted at 2 GPa and 950–1050 °C yield apatite-saturated P contents of olivine in the range ∼360–470 µg g–1. Most P concentrations in olivines from the xenoliths including those in the P-rich rims, however, are significantly lower than the apatite-saturated values, which indicates disequilibrium uptake of P during growth of the P-rich rims by dissolution–reprecipitation. Diffusion modeling indicates that the P zoning must have formed within decades prior to the eruption of the host basalts. This is consistent with the preservation of Li disequilibrium partitioning between olivine and pyroxenes in some of the xenoliths. All metasomatic phenomena were assigned to two metasomatic events, both of which were in close temporal relation with the eruption of the xenolith host basalts: an older event-1 formed type-I apatite, hydrous silicates, calcite and orthopyroxene and caused the modification of type-I apatite composition towards that of type-II. It is also likely to be responsible for whitlockite formation and P zoning in olivine. A younger event-2 comprises all paragenetic, textural and compositional modifications of the xenolith assemblages associated with the infiltration of basaltic melts.