Revisiting Mt Fuji's groundwater origins with helium, vanadium and environmental DNA tracers.

Known locally as the water mountain, for millennia Japan's iconic Mt Fuji has provided safe drinking water to millions of people via a vast network of groundwater and freshwater springs. Groundwater, which is recharged at high elevations, flows down Fuji's flanks within three basaltic aquifers, ultimately forming countless pristine freshwater springs among Fuji's foothills. Here we challenge the current conceptual model of Fuji being a simple system of laminar groundwater flow with little to no vertical exchange between its three aquifers. This model contrasts strongly with Fuji's extreme tectonic instability due to its unique location on top of the only known continental trench-trench-trench triple junction, its complex geology and its unusual microbial spring water communities. On the basis of a unique combination of microbial environmental DNA, vanadium and helium tracers, we provide evidence for prevailing deep circulation and a previously unknown deep groundwater contribution to Fuji's freshwater springs. The most substantial deep groundwater upwelling has been found along Japan's most tectonically active region, the Fujikawa-kako Fault Zone. Our findings broaden the hydrogeological understanding of Fuji and demonstrate the vast potential of combining environmental DNA, on-site noble gas and trace element analyses for groundwater science.

Migration of As, and (3)H/(3)He ages, in groundwater from West Bengal: Implications for monitoring.

From 2002 to 2010 inclusive we monitored concentrations of arsenic (As) and major ions (Ca, Mg, Sr, Na, K, Fe, Mn, Cl, and SO(4)) in groundwater from 14 domestic wells and three piezometer nests in a shallow aquifer (<60 m depth), and 3 wells in a deep aquifer (>70 m depth), in southern West Bengal, India. In the deep aquifer, concentrations of As did not change over time despite increases in the concentration of Fe in two wells. The shallow aquifer occurs in two sedimentological settings: palaeo-channel and palaeo-interfluve. At the top of the shallow aquifer of the palaeo-channel, decreases in all constituent concentrations with time, and an (3)H/(3)He age of 1.4 years, proves that the aquifer is beginning to be flushed of pollutants. In As-polluted groundwater (>50 microg/L As) tapped from deeper grey sands of the shallow, palaeo-channel, aquifer, concentrations of As were mostly stable over time, but both increases and decreases occurred with time in response to downward migration of the chemically-stratified water column. In groundwater tapped from Pleistocene brown sands, the concentration of As remained either low and stable (<2 microg/L As), or increased at rates up to 34 microg/L per year. The increases were caused by the flow of As-rich groundwater either downward into brown sand at the base of palaeo-channels, or laterally into a confined, unpolluted, palaeo-interfluvial, aquifer of brown sand that lies regionally beneath a palaeosol. Under the present pumping regime, the prognosis for As-pollution in the shallow aquifer is complex. Wells in brown sand may become polluted over timescales of as little as 2 years, whilst some wells tapping As-polluted groundwater from grey sand will become fit for potable use (<50 microg/L) within a few decades. The evidence of flushing, and of declining As in some of the groundwater from palaeo-channels, which are conduits for recharge of the confined, As-free, palaeo-interfluve aquifer, and probably also the deeper aquifer, offers hopes that the spread of As-pollution will be limited.

Noble gas and major element constraints on the water dynamics in an alpine floodplain.

The hydrogeological system of an ecologically sensitive alpine floodplain in the Valle di Blenio, Switzerland, was investigated using hydrochemical and 3H-3He dating methods. Water samples from six wells and from different surface locations were analyzed. The analysis of the concentrations of major ions in conjunction with age determination by the 3H-3He-method allowed the main hydrological properties of the system to be consistently characterized. Two geochemically distinct water zones can be distinguished: Ca-SO4-dominated water from the main river and Ca-HCO3-dominated floodplain water. The floodplain water component characterizes the whole floodplain including the surficial hillslope drainage system. Within the ground water samples, two spatially and temporally different types of water can be determined. A younger (age < 1.5 years), less mineralized water is found in the upper part of the aquifer during the summer season. The underlying aquifer zone contains older and more highly mineralized water. However, the general hydrochemical characterization of both types of ground water is similar. In winter, the water ages increase with decreasing ground water levels. Because precipitation is stored temporarily in the snow cover, the contribution of the younger near-surface ground water decreases, resulting in higher apparent water ages and higher mineralization in the upper zone of the aquifer. Water exchange between the main river and the ground water system is limited to ground water exfiltration from the shallow aquifer zone, whereas the hydrochemical separation of the deeper aquifer zone indicates the isolation of the deeper ground water from the main river.

Palaeotemperature reconstruction from noble gases in ground water taking into account equilibration with entrapped air

Noble-gas concentrations in ground water have been used as a proxy for past air temperatures, but the accuracy of this approach has been limited by the existence of a temperature-independent component of the noble gases in ground water, termed 'excess air' whose origin and composition is poorly understood. In particular, the evidence from noble gases in a Brazilian aquifer for a cooling of more than 5 C in tropical America during the Last Glacial Maximum has been called into question. Here we propose a model for dissolved gases in ground water, which describes the formation of excess air by equilibration of ground water with entrapped air in quasi-saturated soils. Our model predicts previously unexplained noble-gas data sets, including the concentration of atmospheric helium, and yields consistent results for the non-atmospheric helium isotopes that are used for dating ground water. Using this model of excess air, we re-evaluate the use of noble gases from ground water for reconstructing past temperatures. Our results corroborate the inferred cooling in Brazil during the Last Glacial Maximum, and indicate that even larger cooling took place at mid-latitudes.

Cool glacial temperatures and changes in moisture source recorded in oman groundwaters

Concentrations of atmospheric noble gases (neon, argon, krypton, and xenon) dissolved in groundwaters from northern Oman indicate that the average ground temperature during the Late Pleistocene (15,000 to 24,000 years before present) was 6.5 degrees +/- 0.6 degrees C lower than that of today. Stable oxygen and hydrogen isotopic groundwater data show that the origin of atmospheric water vapor changed from a primarily southern, Indian Ocean source during the Late Pleistocene to a dominantly northern, Mediterranean source today. The reduced northern water vapor source is consistent with a drier Last Glacial Maximum through much of northern Africa and Arabia.

Climate and groundwater recharge during the last glaciation in an ice-covered region

A multitracer study of a small aquifer in northern Switzerland indicates that the atmosphere in central Europe cooled by at least 5 degreesC during the last glacial period. The relation between oxygen isotope ratios (delta18O) and recharge temperatures reconstructed for this period is similar to the present-day one if a shift in the delta18O value of the oceans during the ice age is taken into account. This similarity suggests that the present-day delta18O-temperature relation can be used to reconstruct paleoclimate conditions in northern Switzerland. A gap in calculated groundwater age between about 17,000 and 25,000 years before the present indicates that during the last glacial maximum, local groundwater recharge was prevented by overlying glaciers.

[Rabies Tissue Culture Infection Test as an Alternative for the Mouse Inoculation Test]

Rabies has disappeared from large parts of Switzerland. Due to systematic oral fox-vaccination campaings that started in 1987, cases of rabies in wild and domestic animals have been confined to the western frontier with France in the last three years. Nevertheless, some cases of severe exposition of man by rabid or rabies-suspect animals still occur. Rabies can be diagnosed in brain smears of infected animals with high specificity and sensitivity by a direct immunofluorescence method. According to WHO recommendations, negative results are to be confirmed in cases of a human exposition by intracerebral inoculation of brain suspensions in three-weeks-old mice. This method has an excellent sensitivity and is able to detect false-negative results in immunofluorescence, which occur in a very small percentage (0.043%). The disadvantage of this confirmatory assay is the sacrification of relatively high numbers of mice (in the Swiss rabies center about 1,300 animals each year), and the long time required for a final diagnosis: 7-20 days in positive, 21 days in negative cases. The cultivation of virus from brain suspensions on a mouse neuroblastoma cell line is a tempting alternative to the mouse inoculation test. This method usually provides a conclusive diagnosis within a few days. However, in our hands it showed in preliminary experiments an unsatisfactory sensitivity (80.7%). The necessity to carry out strict reproducibility controls in this assay has to be emphasized. Further work must be invested in the improvement of the rabies tissue culture infection test and a careful long-term comparison with the mouse inoculation test will be necessary before the mouse inoculation test can be replaced.

Rabies epidemiology, natural barriers and fox vaccination.

Rabies in Central Europe is maintained and spread by red foxes (Vulpes vulpes). The epidemiology is explained by a variety of parameters of the main host. Certain natural and artificial topographic features may function as barriers to the spread of the virus within fox populations. Taking into account epidemiological barriers greatly facilitated the strategic application of oral immunization of foxes for freeing Switzerland from rabies.

Effects of vitamin K deficiency, warfarin, and inhibitors of protein synthesis upon the plasma levels of vitamin K-dependent clotting factors in the chick.

Two-week-old chicks adequate in vitamin K showed a relative lack of vitamin K-dependent clotting factors when compared with the rat, cow, and man. Chick prothrombin was 50%, IX 8%, and X 6% of respective levels in the rat. Factor VII was not detectable in chick plasma. When 1-day-old chicks were fed a vitamin K-deficient diet, prothrombin levels fell to 5% in 5 days, whereas factors IX and X fell to only 60% of normal. After warfarin administration to normal chicks, prothrombin levels fell to 20% in 6 hours, whereas factors IX and X fell to 60%. When cycloheximide was given to normal chicks, all vitamin K-dependent factors fell at the same relative rate with a half time of 2 hours. Cycloheximide also completely blocked the effect of physiological doses (10 mug) of phylloquinone upon prothrombin synthesis, but only partially blocked the effect of pharmacological doses (2.5 mg) of phylloquinone, suggesting an antagonism between cycloheximide and vitamin K at the ribosomal level. Puromycin was effective in blocking the action of vitamin K at both physiological and pharmacological doses. In the chick, unlike the rat, it appears that (1) cycloheximide is fully effective in blocking the action of physiological doses of vitamin K and (2) the regulatory systems for factors IX and X appear to have a higher affinity for vitamin K and a lower affinity for warfarin than the regulatory system for prothrombin.