Thermal Spring Water Research Articles

Assessment of reservoir temperatures of thermal springs of the northern areas of Pakistan by chemical and isotope geothermometry

Chemical and isotope geothermometers, i.e. the Na–K, K–Mg, quartz and δ 18O(SO 4–H 2O), have been applied to estimate the reservoir temperature of the thermal springs in the northern areas of Pakistan. The chemical types of the thermal waters and the effects of mixing of shallow cold water with the thermal end-members are discussed. These waters are neutral to slightly alkaline and have low dissolved contents. Sodium is the dominant cation in almost all the cases. In terms of anions, the hot waters of Budelas are of the SO 4 type, those of Tatta Pani are of mixed character (SO 4 and HCO 3), and the waters from the remaining areas show HCO 3 domination. An absence of tritium in Tatta Pani and Tato thermal springs indicates that they do not have any contribution of shallow young water. In the case of the Murtazabad springs, the wide range of tritium concentrations, negative correlations with surface temperature and Cl, and positive correlation between Na and Cl show that the shallow cold groundwater is mixing with thermal water in different proportions. For the mixed water of Murtazabad thermal springs, ‘isochemical modelling’ using the Na–K, K–Mg and quartz geothermometers indicates an equilibrium temperature in the range 185–200 °C. The δ 18O(SO 4–H 2O) geothermometer gives relatively low temperatures for three springs, whereas two samples are close to the 185–200 °C temperature interval. The reservoir temperatures of Tatta Pani springs (100–120 °C), determined by Na–K and quartz geothermometers, are in good agreement. The δ 18O(SO 4–H 2O) geothermometer gives a relatively higher range (140–150 °C) for most of the Tatta Pani springs. For Tato spring, the isotope and chemical geothermometers (except for the K–Mg) agree on an equilibrium temperature of about 170 °C. Reservoir temperatures of the remaining minor fields are not conclusive due to the lack of sufficient data.

Uranium and radium in groundwater and surface water samples in Morocco

Activities and activity ratios of uranium and radium isotopes ( 234U, 238U, 226Ra, 228Ra, 234U/ 238U, 226Ra/ 238U, 228Ra/ 226Ra) have been determined for 15 wells, 14 hot springs, 7 cold springs and 11 rivers. Activities of the radium isotopes were measured by ultra gamma spectrometry using a low background and high efficiency well type germanium detector whereas those of uranium were counted in an alpha spectrometer. The minimal, maximal and average values are reported here for each water source. The obtained results show that, unlike well waters, the thermal spring waters present relatively low 238U activities and elevated 226Ra activities and 234U/ 238U activity ratios. Uranium and radium activities are similar to those published for other non polluting regions of the world.

Non-magmatic fracture-controlled hydrothermal systems in the Idaho Batholith: South Fork Payette geothermal system

Non-magmatic, fracture-controlled hydrothermal systems located within and near the Idaho batholith have been examined and evaluated for potential application as natural analogues to high-level nuclear waste repositories. Detailed geochemical, petrologic, and structural studies of hot springs along the South Fork of the Payette River (SFPR) in central Idaho, USA, have been combined to assess the nature of a hydrothermal aquifer system along a major brittle shear zone. Geochemical modeling of thermal spring water chemistry with SOLVEQ [Reed, M.H., 1992. SOLVEQ: Users Manual. Unpublished Report, Dept. Of Geological Sciences, University Of Oregon, Eugene, OR.] indicates reservoir temperatures of 85°C to 160°C, and an alteration assemblage consisting of several clays, chlorite, serpentinites, quartz, albite, microcline, and micas. Geothermometry calculations, coupled with independent estimates of geothermal gradients based on heat flow and regional geology, allow estimation of reservoir depths ranging from 2.4 to 6.7 km. Comparison of trace element, rare earth element, and SOLVEQ alteration assemblages supports the hypothesis that waters equilibrated with granitic rocks at depth and ascended to the surface in a short time span. Stable isotope data (δD=−138.4‰ to −148.4‰ and δ 18O=−17.5‰ to −19.4‰) indicate that thermal waters of meteoric origin have interacted with country rocks at a very high water/rock (W/R) ratio. Systematic variations in δD values and the amount of δ 18O shift for thermal waters suggest that recharge probably occurs at much higher elevations than discharge. Fracture orientations, petrologic relations, and geochemical differences between adjacent springs delineate separate hydrothermal systems along the major structure defining the course of the SFPR. Hydrothermal systems along the SFPR exist primarily as small circulation cells which are probably influenced by minor changes in geothermal gradients associated with different rock types. These subsystems are dependent on periodic seismic or microseismic activity to maintain flowpaths. A working model of deep, fracture-controlled hydrothermal convection systems based on the SFPR Geothermal System may be used to evaluate the long-term behavior of artificial hydrothermal systems associated with high-level nuclear waste repositories.

Silicon isotope study of thermal springs in Jiaodong Region, Shandong Province

Based on δ30Si and δ32Si isotope geochemistry, the origin and evolutionary mechanism of thermal springs in Jiaodong region are studied. The mean value of δ30Si of dissolved silica of thermal spring water in Jiaodong is 0.1‰. Thermal spring water ages using δ32Si dating method range from 387a to 965a.

The influence of water–rock interaction on the chemistry of thermal springs in western Canada

A comparison of new data with historical records indicates that the chemistry of thermal springs from the Canadian Cordillera is constant through time, suggesting that water compositions develop equilibrium with the host rock. A thermodynamic model is used to evaluate the influence of water–rock interaction on the chemistry of thermal spring waters. An isotope mass-balance approach is used to evaluate biological controls on the S and C cycles in the springs. A comparison of mineral stability with water compositions suggests that the activities of major cations are controlled by equilibrium reactions with common rock forming minerals and alteration products. Sulfur has a complex redox history in thermal springs. Sulfate derived from dissolution of evaporite minerals is reduced by bacteria, causing the production of HS −. The loss of HS − from the system appears to be minor, instead it is reoxidized to SO 4 as the spring water ascends to surface. Calculations indicate that the amount of SO 4 that is reduced and reoxidized varies from 0 to 53%. There is an inverse relationship between the proportion of biological cycling of SO 4 and the concentration of SO 4, indicating that SO 4 is not a limiting nutrient in hydrothermal systems. In low alkalinity thermal springs, HCO 3 is derived from either dissolution of carbonate minerals or oxidized organic matter. However, for high alkalinity springs (>100 mg/l) HCO 3 is dominantly derived from carbonate dissolution.

Biofilm exopolymers control microbialite formation at thermal springs discharging into the alkaline Pyramid Lake, Nevada, USA

Calcium carbonate precipitation and microbialite formation at highly supersaturated mixing zones of thermal spring waters and alkaline lake water have been investigated at Pyramid Lake, Nevada. Without precipitation, pure mixing should lead to a nearly 100-fold supersaturation at 40oC. Physicochemical precipitation is modified or even inhibited by the properties of biofilms, dependent on the extent of biofilm development and the current precipitation rate. Mucus substances (extracellular polymeric substances, EPS, e.g., of cyanobacteria) serve as effective Ca 2C -buffers, thus preventing seed crystal nucleation even in a highly supersaturated macroenvironment. Carbonate is then preferentially precipitated in mucus-free areas such as empty diatom tests or voids. After the buffer capacity of the EPS is surpassed, precipitation is observed at the margins of mucus areas. Hydrocarbon biomarkers extracted from (1) a calcifying Phormidium-biofilm, (2) the stromatolitic carbonate below, and (3) a fossil ‘tufa’ of the Pleistocene pinnacles, indicate that the cyanobacterial primary producers have been subject to significant temporal changes in their species distribution. Accordingly, the species composition of cyanobacterial biofilms does not appear to be relevant for the formation of microbial carbonates in Pyramid Lake. The results demonstrate the crucial influence of mucus substances on carbonate precipitation in highly supersaturated natural environments. © 1999 Elsevier Science B.V. All rights reserved.

Geochemistry of water and gas discharges from the Mt. Amiata silicic complex and surrounding areas (central Italy)

The Mt. Amiata volcano in central Italy is intimately related to the post-orogenic magmatic activity which started in Pliocene times. Major, trace elements, and isotopic composition of thermal and cold spring waters and gas manifestations indicate the occurrence of three main reservoir of the thermal and cold waters in the Mt. Amiata region. The deepest one is located in an extensive carbonate reservoir buried by thick sequences of low-permeability allochthonous and neo-autochthonous formations. Thermal spring waters discharging from this aquifer have a neutral Ca-SO 4 composition due to the presence of anhydrite layers at the base of the carbonate series and, possibly, to absorption of deep-derived H 2S with subsequent oxidation to SO 4 2− in a system where pH is buffered by the calcite–anhydrite pair ( Marini and Chiodini, 1994). Isotopic signature of these springs and N 2-rich composition of associated gas phases suggest a clear local meteoric origin of the feeding waters, and atmospheric O 2 may be responsible for the oxidation of H 2S. The two shallower aquifers have different chemical features. One is Ca-HCO 3 in composition and located in several sedimentary formations above the Mesozoic carbonates. The other one has a Na-Cl composition and is hosted in marine sediments filling many post-orogenic NW–SE-trending basins. Strontium, Ba, F, and Br contents have been used to group waters associated with each aquifer. Although circulating to some extent in the same carbonate reservoir, the deep geothermal fluids at Latera and Mt. Amiata and thermal springs discharging from their outcropping areas have different composition: Na-Cl and Ca-SO 4 type, respectively. Considering the high permeability of the reservoir rock, the meteoric origin of thermal springs and the two different composition of the thermal waters, self-sealed barriers must be present at the boundaries of the geothermal systems. The complex hydrology of the reservoir rocks greatly affects the reliability of geothermometers in liquid phase, which understimate the real temperatures of the discovered geothermal fields. More reliable temperatures are envisaged by using gas composition-based geothermometers. Bulk composition of the 67 gas samples studied seems to be the result of a continuous mixing between a N 2-rich component of meteoric origin related to the Ca-SO 4 aquifer and a deep CO 2-rich component rising largely along the boundaries of the geothermal systems. Nitrogen-rich gas samples have nearly atmospheric N 2/Ar (=83) and 15 N / 14 N ( δ=0‰) ratios whereas CO 2-rich samples show anomalously high δ 15N values (up to +6.13 ‰), likely related to N 2 from metamorphic schists lying below the carbonate formations. On the basis of average 13 C / 12 C isotopic ratio ( δ 13C around 0‰), CO 2 seems to originate mainly from thermometamorphic reactions in the carbonate reservoir and/or in carbonate layers embedded in the underlying metamorphic basement. Distribution of 3 He / 4 He isotopic ratios indicates a radiogenic origin of helium in a tectonic environment that, in spite of the presence of many post-orogenic basins and mantle-derived magmatics, can presently be considered in a compressive phase.

Chemical patterns of thermal aquifers in the volcanic islands of the Aegean Arc, Greece

Thermal spring waters and associated gases discharging on several volcanic islands and on mainland Greece along the Hellenic Volcanic Arc (HVA) in the south Aegean sea have been investigated. The chemical characteristics of most of the spring waters suggest that the water in their feeding aquifers is largely derived from seawater that enters the hydrological circuits and mixes with local neutral low-salinity bicarbonate waters. There are however discrepancies between the simple theoretical mixing line between local meteoric waters and seawater, and the actual mixing line. This mixing is accompanied by partial Mg and SO 4 precipitation to secondary minerals and by the addition of K, Ca, HCO 3, B, NH 4, and SiO 2 to the solutions as a result of water-rock interaction processes. At Milos and Nisyros, where active hydrothermal systems are present at shallow depth, the silica content of the thermal springs is much higher than that of springs on the other islands and mainland Greece. This suggests higher thermal gradients at depth there, and the ascent of geothermal fluids to the surface along fractures prevalently located in the fumarolic fields within the latest eruptive centers and calderas. The fact that the springs are anomalously enriched in silica only at Milos and Nisyros suggests indirectly that, apart from Santorini island, where steam vents are present at the surface, the fluids from the active high-enthalpy geothermal systems do not rise to the surface anywhere else along the HVA. If present, they are well confined under thick and impermeable covers.

The chemical and isotopic composition of fumarolic gases and spring discharges from Galeras Volcano, Colombia

Galeras fumarole discharges have been collected since its reactivation, in 1988, through December 1995. The gases are dominated by H 2O, CO 2, S (as SO 2 and H 2S) and HCl. The relative proportions of these gases classify them as ‘magmatic’. Thermodynamic equilibrium temperatures of the gases range from 260 to > 600 °C. The relative abundance of inert gases, N 2, Ar and He, can be used as ‘tracers’ to identify the source of the fumarole discharges. At Galeras the majority of the samples have a composition characteristic of gases originating from arc-related magmas, with relatively high N 2 contents and minor He and Ar. During 1993, the year of frequent eruptions, the gas composition changed to basaltic or ‘mantle-derived’ gases, with significantly higher He contents. This is interpreted to be the result of injection of volatiles from a basaltic magma body at depth prior to and during the increased eruptive activity of 1993. The δ 13C values for CO 2 in fumarole discharges are typical of andesitic volcanoes and may indicate addition of MORB-derived CO 2. The δ 15N values for N 2 may indicate significant contribution of N 2 from marine sediments and only minor contribution of MORB-derived N 2. The δ D and δ 18O values of the discharging steam lie on a mixing trend between the isotopic composition of ‘arc-related’ magmatic water and 18O-shifted meteoric water. The most magmatic discharges have δ D values of −30 to −35‰; while the most meteoric discharges have values of −70 to −75‰, similar to Galeras thermal spring waters. Galeras thermal water discharges consist of acid sulfate and bicarbonate waters.S/Cl ratios in the acid sulfate waters are similar to fumarole ratios, suggesting direct absorption of magmatic gases into shallow ground waters. This is supported by the essentially meteoric δD and δ 18O values of the discharges and by elevated 3He/ 4He ratios of thermal spring waters. The absorption of acid S- and Cl-rich gases yield acid waters which are capable of dissolving rocks. The thermal waters, however, are far from equilibrium with Galeras lavas and pyroclastic rocks, providing evidence of the immaturity of the Galeras hydrothermal system. The SO 4 and Cl content, as well as the O and H isotopic composition of Galeras thermal springs vary with the activity of the volcano. The 7-year sampling program at Galeras revealed intriguing results concerning the activity of Galeras, its magmatic-hydrothermal system and the origin of the volatiles. Despite decreasing outlet temperatures since 1992, deep temperatures remain high, implying continued unrest in the Galeras magmatic system.

Permeabilities and Chemical Properties of Water in Crystalline Rocks of the Black Forest, Germany

Investigations were carried out to determine the hydraulic and hydrochemical properties of crystalline rocks in the Black Forest of Germany and neighbouring regions. Rock permeabilities (K) were determined to a depth of 3500 m. These parameters range from K = 3.5 × 10-10 ms-1 to K = 8.7 × 10-5 ms-1; and can increase up to an order of magnitude which is typical for porous aquifers. It is shown that on an average, granites are more pervious than gneisses and only the permeabilities of gneisses decrease with depth. The geochemistry of natural waters in crystalline rocks is not constant, but varies with depth and location. The concentration increases with depth and the water-type changes from a Ca–-Na–-HCO 3-type (or Na–-Ca–-HCO3–-) at shallow depths to a Na–-Cl-type at greater depths. Thermal springs are found only in granitic rocks with on average higher permeabilities than in gneisses. Thermal waters are welling up in valleys at the bottom of steep mountains. The chemical composition of thermal spring water is identical to that of water found at greater depths. Using geothermometers it is found, that the depth of the deposits of thermal spring water in the crystalline basement rocks of the Black Forest is some 1000 m below the surface. The topographic relief in the mountains induces a deep circulation of infiltrating rain-water with an upwelling as thermal springs in the valleys.

Badgastein spa?Austrian central Alps

The Badgastein spa shows almost all the special geological and hydrological features existing in the northeastern central Alps. Situated within the Tauern window, the open joint system enables the infiltration of surface water to great depths. There it becomes heated and loaded with radon and trace elements such as fluor. The water discharges as thermal water springs at the steep right flank of the cascade of the Gastein-Ache. This hydraulic process occurs during a span of 3600–3800 years. The springs are captured in galleries, and the largest discharge is in gallery IX (2518 m3/d−1). The spa became known worldwide in the 19th century by visiting aristocrats from Central and Eastern Europe. The most important event in the 20th century was the discovery of the heat joint in the Bockstein gallery. In 1940 an effort to reactivate gold mining in the Radhausberg near Bockstein south of Badgastein failed. However, the miners had the unexpected experience of being cured of rheumatism. A connection between the great depth and high temperature in the gallery was made by the discovery of the joint set with heat and radon emanation. In the medical stations of the Bockstein gallery treatment of polyarthritis has become especially successful.

Environmental factors and the development of Bath Spa, England

Thermal water springs at Bristol and Bath in west England have come under close scrutiny since the closure of Bath Spa in 1978. In order to protect the hot springs from dewatering and loss of pressure due to largescale quarrying and deep drilling, it is necessary to identify the sources and routes whereby the thermal water travels to its resurgences in the Avon valley. Control over deep water movements is exercised by the structure and size of the aquifers and aquicludes, modified by zones of Quaternary—Recent fracturing along which water movements have not been restricted or blocked by mineralization.

Geothermics of the Albanides

Some results of the geothermal investigations carried out in Albania are treated here. The position of the Albanides in the Alpine Mediterranean orogenic belt and the method of temperature recording in deep oil and gas wells and also in mines is briefly described. The geothermal data have been analysed and coordinated with knowledge of the regional geology of the tectonic zones of the Albanides. The characteristics of thermal spring waters are briefly described.

The geyser bight geothermal area, Umnak Island, Alaska

The Geyser Bight geothermal area contains one of the hottest and most extensive areas of thermal springs in Alaska, and is the only site in the state with geysers. Heat for the geothermal system is derived from crustal magma associated with Mt. Recheshnoi volcano. Successive injections of magma have probably heated the crust to near its minimum melting point and produced the only high-SiO 2 rhyolites in the oceanic part of the Aleutian arc. At least two hydrothermal reservoirs are postulated to underlie the geothermal area and have temperatures of 165° and 200°C, respectively, as estimated by geothermometry. Sulfate-water isotope geothermometers suggest a deeper reservoir with a temperature of 265°C. The thermal spring waters have relatively low concentrations of Cl (600 ppm) but are rich in B (60 ppm) and As (6 ppm). The As/Cl ratio is among the highest reported for geothermal waters.

Geochemistry of waters in the Valley of Ten Thousand Smokes region, Alaska

Meteoric waters from cold springs and streams outside of the 1912 eruptive deposits filling the Valley of Ten Thousand Smokes (VTTS) and in the upper parts of the two major rivers draining the 1912 deposits have similar chemical trends. Thermal springs issue in the mid-valley area along a 300-m lateral section of ash-flow tuff, and range in temperature from 21 to 29.8°C in early summer and from 15 to 17°C in mid-summer. Concentrations of major and minor chemical constituents in the thermal waters are nearly identical regardless of temperature. Waters in the downvalley parts of the rivers draining the 1912 deposits are mainly mixtures of cold meteoric waters and thermal waters of which the mid-valley thermal spring waters are representative. The weathering reactions of cold waters with the 1912 deposits appear to have stabilized and add only subordinate amounts of chemical constituents to the rivers relative to those contributed by the thermal waters. Isotopic data indicate that the mid-valley thermal spring waters are meteoric, but data is inconclusive regarding the heat source. The thermal waters could be either from a shallow part of a hydrothermal system beneath the 1912 vent region or from an incompletely cooled, welded tuff lens deep in the 1912 ash-flow sheet of the upper River Lethe area. Bicarbonate-sulfate waters resulting from interaction of near-surface waters and the cooling 1953–1968 southwest Trident plug issue from thermal springs south of Katmai Pass and near Mageik Creek, although the Mageik Creek spring waters are from a well-established, more deeply circulating hydrothermal system. Katmai caldera lake waters are a result of acid gases from vigorous drowned fumaroles dissolving in lake waters composed of snowmelt and precipitation.

PHYSICAL, CHEMICAL, AND DISTRIBUTIONAL ASPECTS OF CANADIAN SPRINGS

AbstractSprings, or points of natural, concentrated groundwater discharge, may be located in river or lake beds, or below mean sea level along the coast, but many are found some distance from surface-water bodies. Spring water commonly represents rain or snow-melt that has entered the ground at a higher elevation a number of years earlier.Measured springwater temperatures in Canada range from very cold (−2.9 °C) to hot (82.2 °C). Thermal spring waters, with temperatures above the local mean-annual air temperature, have undergone geothermal heating during deep subsurface circulation in areas of high topographic relief. Hot springs (>37 °C) are therefore found only in mountainous areas, in Alberta, British Columbia, Yukon, and the Northwest Territories. Spring locations are commonly controlled by major folding or faulting, or both, in the bedrock strata.Reported pH values in Canadian spring waters range from strongly acidic to alkaline (2.8 to >10.0). Low pH values (<4.0) are associated with high contents of dissolved Fe (up to 2600 mg·L−1) and other heavy metals (e.g. Zn up to 177 mg·L−1), resulting from the oxidation of metal sulfides. Measured redox potentials (Eh) range from −252 to +683 mV. Negative Eh values are found in spring waters that contain dissolved H2S and S2−, produced by bacterial reduction of dissolved sulfate.Total-dissolved-solids contents of Canadian spring waters are reported to range from as little as 32 to over 75 000 mg·L−1. Chemical composition also varies widely. Major anions include bicarbonate (up to 5960 mg·L−1), sulfate (up to 17 520 mg·L−1), and chloride (up to 44 300 mg·L−1). Major cations include calcium (up to 1823 mg·L−1), magnesium (up to 1190 mg·L−1), sodium (up to 27 100 mg·L−1, and potassium (up to 1568 mg·L−1). The chemical composition of each spring water reflects the mineral composition of the rock types with which the water has been in contact, as well as its subsurface residence time. In simplified terms, Ca–Mg/HCO3 waters come from carbonate rock (limestone, dolomite), Ca/SO4 waters from gypsum or anhydrite, and Na/Cl waters from salt beds.Springwater temperature and composition can both show gradual (seasonal) and sudden (incidental) variations. In springs that show seasonal variations, maximum temperature and mineralization occur near the end of winter; minimum values commonly occur during snowmelt. Sudden variations in temperature, mineralization, and discharge rate can occur during periods of heavy rain, if cold, non-mineralized rainwater enters spring conduits. Earthquakes may cause sudden changes in discharge rates and suspended-solids contents, without affecting water temperature or chemical composition.Information on Canadian spring locations, and on their physical and chemical character, is still spotty. As detailed knowledge about springs can be useful in both ecological and water-supply studies, an effort should be made to expand and refine the existing database.

Geochemical studies of the Tongyoung gold-silver deposits, Republic of Korea; evidence of meteoric water dominance in a Te-bearing epithermal system

Epithermal gold-silver vein mineralization of the Tongyoung mine was deposited in five stages (I to V) of quartz-rhodochrosite-calcite-sulfide veins (0.3-7.0 m thick) which fill fault planes in Cretaceous volcanic rocks of the Gyeongsang basin. K-Ar dating of alteration sericite (72.9 + or - 1.2 Ma) indicates a Late Cretaceous age for ore mineralization. Stages I and II are Au-Ag-bearing, whereas stages III, IV, and V are barren. Ore grades average 12 g/metric ton gold with a gold/silver ratio of 1:11. Stage II is composed of five rhythmically banded substages which show a progressive change in ore mineralogy with increasing paragenetic time: electrum (68 wt % Au) --> electrum (65 wt % Au) + argentitc --> electrum (50 wt % Au) + Ag tellurides --> Ag tellurides + native silver. The shift in mineralogy reflects decreases in temperature and fugacity of sulfur, with a concomitant increase in fugacity of tellurium.Fluid inclusion data indicate a history of progressive cooling and dilution of ore-forming fluids. During stages I and II, higher temperature and salinity fluids (260 degrees C, 6 equiv wt % NaCl) mixed with cooler, less saline waters, resulting in most ore deposition from fluids of intermediate temperature and composition (190 degrees -230 degrees C, 2.5-4.5 equiv wt % NaCl). Continued cooling and dilution (coupled with decreasing fugacity of sulfur) resulted in deposition of Ag-Te mineralization and ultimately in barren stage III and IV quartz and stage V calcite. Stable isotope compositions of mineralizing fluids from Tongyoung (delta D = -44 to -61ppm; delta 18 O = -6.8 to -9.4ppm) are similar to modern meteoric and thermal spring waters in the area and indicate meteoric water dominance during all stages of the Au-Ag-Te mineralizing system. Comparison of Tongyoung to other Au-Ag-(Te) deposits indicates that its complex sequence of mineralization is a natural consequence of repeated inundation of a hydrothermal system by progressively cooler meteoric waters.

Aerosol Spa Therapy in France

ABSTRACT In France and other European countries, natural thermal spring waters have been used for centuries to treat countless patients. Because of the methods and conditions of cure advocated for these waters, they had never until recently been seriously considered as a drug. However, extensive work carried out in French spas has provided scientific evidence in support of the therapeutic usefulness of spa treatment. This review presents the evidence in favour of aerosol treatment of broncho-pulmonary conditions with thermal water in certain spas. It successively discusses the historical background of these waters, their physical, chemical and bacteriological properties, their mode of administration, their pharmacological activity on isolated organs, whole animals and enzymes, their pharmacokinetics after administration to animals and man, their clinical pharmacology in animals and man and finally their clinical activity. Despite the inescapable difficulties encountered in evaluating spa treatment, the mo...

The evolution of thermal structure and water chemistry in Lake Nyos

Abstract We collected a time series of physical and chemical data to gain a better understanding of the dynamics of Lake Nyos. Measurements of water and gas chemistry, and temperature made during January, March, and May 1987 are compared to data taken in September 1986 just after the initial CO2 gas release. There is no pattern of change in overall heat content of the lake, although heat input to bottom waters (185–208 m) has occurred at a rate of 1600 mW m−2. This increase in heat content translates to a change from 23.38 to 24.12°C at 200 m and can be explained by geothermal heat flow and addition of thermal spring water. Concentrations of Ca2+, Mg2+, Na+, K+, Fe2+ and alkalinity have increased only in bottom waters. In situ lake processes such as sulfate and iron reduction are unable to account for the changes in alkalinity. Observed chemical changes are consistent with a scenario where slightly thermal soda water is being input to the bottom of the lake. Measurements of pCO2 at depth ranged from 18 to 28% of saturation and exhibited horizontal variability. Overall recharge of CO2 in bottom waters is negligible. Mainly because of increasing ion concentrations in bottom water, total stability of the water column increased 33% from 48,800 J m−2 in September 1986 to 64,700 J m−2 in May 1987. As long as CO2 concentrations remain the same, this level of stability is higher than could be disrupted by common limnologic or meteorologic processes. There is thermal and chemical evidence that a buildup of dissolved iron and CO2 in bottom waters must have preceded the August 1986 gas release. In addition, a survey of all crater lakes in Cameroon indicates that only Lakes Nyos and Monoun contain high concentrations of dissolved iron and CO2. Thus there is a low probability of any other Cameroonian lake releasing a substantial volume of CO2.

伊豆長岡およびにら山における温泉賦存状態と温泉収支

伊豆長岡およびにら山における温泉賦存状態と温泉収支