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1.
Stable Carbon Isotope Biogeochemistry and Anthropogenic Impacts on Karst Ground Water, Zunyi, Southwest China 总被引:2,自引:0,他引:2
Si-Liang Li Cong-Qiang Liu Yun-Chao Lang Faxiang Tao Zhiqi Zhao Zhihua Zhou 《Aquatic Geochemistry》2008,14(3):211-221
Natural and anthropogenic impacts on karst ground water, Zunyi, Southwest China, are discussed using the stable isotope composition
of dissolved inorganic carbon and particulate organic carbon, together with carbon species contents and water chemistry. The
waters can be mainly characterized as HCO3–Ca type, HCO3 · SO4–Ca type, or HCO3 · SO4–Ca · Mg type, according to mass balance considerations. It is found that the average δ13CDIC values of ground waters are higher in winter (low-flow season) than in summer (high-flow season). Lower contents of dissolved
inorganic carbon (DIC) and lower values of δ13CDIC in summer than in winter, indicate that local rain events in summer and a longer residence time of water in winter play an
important role in the evolution of ground water carbon in karst flow systems; therefore, soil CO2 makes a larger contribution to the DIC in summer than in winter. The range of δ13CDIC values indicate that dissolved inorganic carbon is mainly controlled by the rate of carbonate dissolution. The concentrations
of dissolved organic carbon and particulate organic carbon in most ground water samples are lower than 2.0 mg C L−1 and 0.5 mg C L−1, respectively, but some waters have slightly higher contents of organic carbon. The waters with high organic carbon contents
are generally located in the urban area where lower δ13CDIC values suggest that urbanization has had an effect on the ground water biogeochemistry and might threaten the water quality. 相似文献
2.
The contribution of rain-on-snow (ROS) events to NO3-N levels in stream water has received relatively little research attention. However, individual ROS events during January and February contributed up to 40% of annual NO3-N export from a forested catchment in south-central Ontario between 1980 and 2000, but comprised less than 10% of annual precipitation. Nitrate-N concentrations in stream water increased rapidly following ROS events, and were similar to the concentrations in incident rainfall and the accumulated snow pack, likely due to limited contact of runoff with mineral soil under snow cover and low winter biological activity. Increased NO3-N associated with ROS events resulted in substantial depressions in stream pH and alkalinity, which may delay the biological recovery from acidification. The contribution of ROS events to annual or winter NO3-N export has been generally greater in recent years, although there is a considerable year-to-year variation. As a result, ROS events contribute to inter-annual variability in stream NO3-N concentrations and will have a strong effect on apparent temporal trends. The contribution of ROS events to annual NO3-N export should be considered when assessing surface water recovery from acidification and the N-status of forests, particularly if climate change projections for winter warming result in a greater proportion of winter precipitation occurring as rain. 相似文献
3.
蚯蚓肠道内小分子有机酸与摄入的土壤矿物相互作用,加速矿物溶解。摄入的土壤在蚯蚓肠道内平均停留时间约为12 h,不足以使土壤矿物产生显著的溶解特征,因此这一过程难以在蚯蚓体内进行评估。本研究通过体外实验控制pH值和有机酸浓度,模拟蚯蚓肠道中有机酸对土壤中常见矿物的溶解反应,探讨了方解石和钾长石在蚯蚓肠道环境中的初始溶解动力学。研究发现,矿物在混合有机酸中的溶解速率比在纯水中高一个数量级,说明有机配体和质子促进了矿物溶解。溶解速率及粒度分析表明,方解石(CaCO3)溶解速率不受溶解过程中粒度变化的影响,而钾长石(KAlSi3O8)粒度在溶解期间未出现显著变化。在此基础上,采用初始速率法模拟了钾长石的初始溶解动力学,计算得出的溶解速率表明钾长石在溶解初期主要为表面K~+的释放。使用缩核模型(shrink core model)和Hixson-Crowell模型对方解石溶解过程进行动力学解析,发现方解石的溶解主要受溶液中反应物内扩散的速率影响。这定量描述了两种矿物在有机酸溶液和纯水中的溶解差异。现有研究表明,有机配体和质子协同促... 相似文献
4.
Tjaša Kanduč Fausto Grassa Jennifer McIntosh Vekoslava Stibilj Marija Ulrich-Supovec Ivan Supovec Sergej Jamnikar 《Hydrogeology Journal》2014,22(4):971-984
The geochemical and isotopic composition of surface waters and groundwater in the Velenje Basin, Slovenia, was investigated seasonally to determine the relationship between major aquifers and surface waters, water–rock reactions, relative ages of groundwater, and biogeochemical processes. Groundwater in the Triassic aquifer is dominated by HCO3 –, Ca2+, Mg2+ and δ13CDIC indicating degradation of soil organic matter and dissolution of carbonate minerals, similar to surface waters. In addition, groundwater in the Triassic aquifer has δ18O and δD values that plot near surface waters on the local and global meteoric water lines, and detectable tritium, likely reflecting recent (<50 years) recharge. In contrast, groundwater in the Pliocene aquifers is enriched in Mg2+, Na+, Ca2+, K+, and Si, and has high alkalinity and δ13CDIC values, with low SO4 2– and NO3 – concentrations. These waters have likely been influenced by sulfate reduction and microbial methanogenesis associated with coal seams and dissolution of feldspars and Mg-rich clay minerals. Pliocene aquifer waters are also depleted in 18O and 2H, and have 3H concentrations near the detection limit, suggesting these waters are older, had a different recharge source, and have not mixed extensively with groundwater in the Triassic aquifer. 相似文献
5.
Clare E. Reimers H. Tuba Özkan-Haller Rhea D. Sanders Kristina McCann-Grosvenor Peter J. Chace Sean A. Crowe 《Aquatic Geochemistry》2016,22(5-6):505-527
Mid-shelf sediments off the Oregon coast are characterized as fine sands that trap and remineralize phytodetritus leading to the consumption of significant quantities of dissolved oxygen. Sediment oxygen consumption (SOC) can be delayed from seasonal organic matter inputs because of a transient buildup of reduced constituents during periods of quiescent physical processes. Between 2009 and 2013, benthic oxygen exchange rates were measured using the noninvasive eddy covariance (EC) method five separate times at a single 80-m station. Ancillary measurements included in situ microprofiles of oxygen at the sediment–water interface, and concentration profiles of pore water nutrients and trace metals, and solid-phase organic C and sulfide minerals from cores. Sediment cores were also incubated to derive anaerobic respiration rates. The EC measurements were made during spring, summer, and fall conditions, and they produced average benthic oxygen flux estimates that varied between ?2 and ?15 mmol m?2 d?1. The EC oxygen fluxes were most highly correlated with bottom-sensed, significant wave heights (H s). The relationship with H s was used with an annual record of deepwater swell heights to predict an integrated oxygen consumption rate for the mid-shelf of 1.5 mol m?2 for the upwelling season (May–September) and 6.8 mol m?2 y?1. The annual prediction requires that SOC rates are enhanced in the winter because of sand filtering and pore water advection under large waves, and it counters budgets that assume a dominance of organic matter export from the shelf. Refined budgets will require winter flux measurements and observations from cross-shelf transects over multiple years. 相似文献
6.
P. Ya. Tishchenko T. A. Mikhailik G. Yu. Pavlova P. P. Tishchenko A. M. Koltunov Jing Zhang 《Geochemistry International》2017,55(3):282-293
The paper suggests an accurate approach to studying carbonate equilibrium in the water of the Razdol’naya River. The approach involves measuring pH by Pitzer’s scale, using a cell without liquid junction; measuring the total alkalinity by Bruevich’s technique; and using apparent constants of carbonate equilibrium with regard for the organic alkalinity. The Pitzer technique was employed to calculate the apparent constants of carbonate equilibrium in solution that models the riverine water: Ca(HCO3)2–NaCl–H2O within the range of alkalinity of 0–0.005 mol/kg and temperatures of 0–25°C. Carbonate equilibrium in the water of the Razdol’naya River was sampled for studying at eight sites during all four seasons. Although the contents of biogenic compounds in the water are high, they can merely insignificantly affect the acid–base equilibrium, which is controlled in the riverine water by carbonate equilibrium and the concentrations of humic substances, which play the greater role, the greater the discharge of the river. In addition to the production and destruction of organic matter, carbonate equilibrium in the river is also affected by the supply of humic substances with soil waters and total alkalinity with groundwaters. The fluxes of alkalinity and humic substances annually brought by the Razdol’naya River to Amur Bay are evaluated at 1.33 × 109 mol and 9.9 × 106 kgC, respectively. The carbon dioxide export with the Razdol’naya River is equal to the alkalinity flux and does not depend on the weathering mechanisms. 相似文献
7.
Benony K. Kortatsi Collins K. Tay Geophrey Anornu Ebenezer Hayford Grace A. Dartey 《Environmental Geology》2008,53(8):1651-1662
Alumino-silicate mineral dissolution, cation exchange, reductive dissolution of hematite and goethite, oxidation of pyrite
and arsenopyrite are processes that influence groundwater quality in the Offin Basin. The main aim of this study was to characterise
groundwater and delineate relevant water–rock interactions that control the evolution of water quality in Offin Basin, a major
gold mining area in Ghana. Boreholes, dug wells, springs and mine drainage samples were analysed for major ions, minor and
trace elements. Major ion study results show that the groundwater is, principally, Ca–Mg–HCO3 or Na–Mg–Ca–HCO3 in character, mildly acidic and low in conductivity. Groundwater acidification is principally due to natural biogeochemical
processes. Though acidic, the groundwater has positive acid neutralising potential provided by the dissolution of alumino-silicates
and mafic rocks. Trace elements’ loading (except arsenic and iron) of groundwater is generally low. Reductive dissolution
of iron minerals in the presence of organic matter is responsible for high-iron concentration in areas underlain by granitoids.
Elsewhere pyrite and arsenopyrite oxidation is the plausible process for iron and arsenic mobilisation. Approximately 19 and
46% of the boreholes have arsenic and iron concentrations exceeding the WHO’s (Guidelines for drinking water quality. Final
task group meeting. WHO Press, World Health Organization, Geneva, 2004) maximum acceptable limits of 10 μg l−1 and 0.3 mg l−1, for drinking water. 相似文献
8.
Ryoko Fujiyoshi Masanori Okabayashi Yousuke Sakuta Kazumasa Okamoto Takashi Sumiyoshi Ivan Kobal Janja Vaupotič 《Environmental Earth Sciences》2013,70(3):1159-1167
Soil radon (222Rn) has been monitored during winter months under cool-temperate deciduous stands of different surface geology in Tomakomai and in Sapporo, Hokkaido, Japan. Radon level was lower in Tomakomai of immature soil of porous volcanic ash emitted from an active volcano (Mt. Tarumae), compared with those in Sapporo of alluvial sediments. In Tomakomai, mean value of the 222Rn activity concentration was higher in winter (570 Bq m?3) than in summer (350 Bq m?3) at a depth of 1 m, which is consistent with the results in cold and dry winter reported in the literature. In contrast, soil radon decreasing with decreasing soil temperature from mid-September (5.0 kBq m?3) remained low (2.6 kBq m?3) under persistent snow in Sapporo, which had already been observed in the same location. Measurements of the activity concentrations of 222Rn in snow and in snow air as well as in soil air indicate that the small amount of 222Rn is released from the ground surface to the overlying snowpack with a 222Rn flux density of 0.4 mBq m?2 s?1 under thick snow cover in Sapporo. 相似文献
9.
10.
Kaushar Ali Sunil Sonbawane D. M. Chate Devendraa Siingh P. S. P. Rao P. D. Safai K. B. Budhavant 《Journal of Earth System Science》2010,119(6):753-762
Surface snow and lake water samples were collected at different locations around Indian station at Antarctica, Maitri, during December 2004–March 2005 and December 2006–March 2007. Samples were analyzed for major chemical ions. It is found that average pH value of snow is 6.1. Average pH value of lake water with low chemical content is 6.2 and of lake water with high chemical content is 6.5. The Na+ and Cl? are the most abundantly occurring ions at Antarctica. Considerable amount of SO 4 2? is also found in the surface snow and the lake water which is attributed to the oxidation of DMS produced by marine phytoplankton. Neutralization of acidic components of snow is mainly done by NH 4 + and Mg2+. The Mg2+, Ca2+ and K+ are nearly equally effective in neutralizing the acidic components in lake water. The NH 4 + and SO 4 2? occur over the Antarctica region mostly in the form of (NH4)2SO4. 相似文献
11.
Anne-Catherine Pierson-Wickmann Luc Aquilina Jérôme Molénat 《Geochimica et cosmochimica acta》2009,73(16):4688-4704
In natural river systems, the chemical and isotopic composition of stream- and ground waters are mainly controlled by the geology and water-rock interactions. The leaching of major cations from soils has been recognized as a possible consequence of acidic deposition from atmosphere for over 30 years. Moreover, in agricultural areas, the application of physiological acid fertilizers and nitrogen fertilizers in the ammonia form may enhance the cation leaching through the soil profile into ground- and surface waters. This origin of leached cations has been studied on two small and adjacent agricultural catchments in Brittany, western France. The study catchments are drained by two first-order streams, and mainly covered with cambisoils, issued from the alteration and weathering of a granodiorite basement. Precipitations, soil water- and NH4 acetate-leachates, separated minerals, and stream waters have been investigated. Chemical element ratios, such as Ba/Sr, Na/Sr and Ca/Sr ratios, as well as Sr isotopic ratios are used to constrain the relative contribution from potential sources of stream water elements.Based on Sr isotopic ratio and element concentration, soil water- and NH4 acetate leaching indicates (1) a dominant manure/slurry contribution in the top soil, representing a cation concentrated pool, with low 87Sr/86Sr ratios; (2) in subsoils, mineral dissolution is enhanced by fertilizer application, becoming the unique source of cations in the saprolite. The relatively high weathering rates encountered implies significant sources of cations which are not accessory minerals, but rather plagioclase and biotite dissolution.Stream water has a very different isotopic and chemical composition compared to soil water leaching suggesting that stream water chemistry is dominated by elements issued from mineral and rock weathering. Agriculture, by applications of chemical and organic fertilizers, can influence the export of major base cations, such as Na+. Plagioclase dissolution, rather than anthropogenically controlled soil water, seems to be the dominant source of Na+ in streams. However, Ca2+ in streams is mostly derived from slurries and manures deposited on top soils, and transferred into the soil ion-exchange pool and stream waters. Less than 10% of Na+, 5-40% of Sr2+ and 20-100% of Ca2+ found in streams can be directly derived from the application of organic fertilizers. 相似文献
12.
Acid mine drainage (AMD) is treated at several points in the Lausitz lignite mine district (Saxony, Germany) in treatment
plants. The remaining alkaline low density sludge (LDS) was deposited in acidic mining lakes without having an impact on the
lake water quality. Batch experiments show that alkalinity can be raised using LDS from acid mine drainage treatment plants
together with CO2. Batch experiments were conducted using lake water and deposited LDS from the mining lake Spreetal-Nordost with varying concentrations
of CO2. Also the duration of gas contact as well as the LDS–water ratio was changed in the batch experiments. The gas contact time
and the partial pressure of CO2 are the relevant parameters controlling the alkalinity in the lake water at the end of the experiments. The Ca and Mg concentrations
of the pore water are relevant for higher pH values. Therefore, dissolved CO2 can form bicarbonate or carbonate complexes, thus alkalinity rises. A second factor for alkalinity gain is the calcite content
of the sludge, because CO2 triggers the dissolution of carbonates. Therefore, unused calcite in the sludge can raise the alkalinity more effectively
by the application of carbon dioxide. Furthermore, it was shown that remobilization of trace elements will not affect the
water quality. 相似文献
13.
Several important equilibrium Si isotope fractionation factors among minerals, organic molecules and the H4SiO4 solution are complemented to facilitate the explanation of the distributions of Si isotopes in Earth’s surface environments. The results reveal that, in comparison to aqueous H4SiO4, heavy Si isotopes will be significantly enriched in secondary silicate minerals. On the contrary, quadra-coordinated organosilicon complexes are enriched in light silicon isotope relative to the solution. The extent of 28Si-enrichment in hyper-coordinated organosilicon complexes was found to be the largest. In addition, the large kinetic isotope effect associated with the polymerization of monosilicic acid and dimer was calculated, and the results support the previous statement that highly 28Si-enrichment in the formation of amorphous quartz precursor contributes to the discrepancy between theoretical calculations and field observations. With the equilibrium Si isotope fractionation factors provided here, Si isotope distributions in many of Earth’s surface systems can be explained. For example, the change of bulk soil δ30Si can be predicted as a concave pattern with respect to the weathering degree, with the minimum value where allophane completely dissolves and the total amount of sesqui-oxides and poorly crystalline minerals reaches their maximum. When, under equilibrium conditions, the well-crystallized clays start to precipitate from the pore solutions, the bulk soil δ30Si will increase again and reach a constant value. Similarly, the precipitation of crystalline smectite and the dissolution of poorly crystalline kaolinite may explain the δ30Si variations in the ground water profile. The equilibrium Si isotope fractionations among the quadra-coordinated organosilicon complexes and the H4SiO4 solution may also shed light on the Si isotope distributions in the Si-accumulating plants. 相似文献
14.
Matías Mudarra Bartolomé Andreo Juan Antonio Barberá Jacques Mudry 《Environmental Earth Sciences》2014,71(2):507-523
Analysis of Total Organic Carbon (TOC) and NO3 ? contents in the water at six springs in the province of Malaga (Southern Spain), sampled under different hydrologic conditions, revealed two different hydrochemical behaviour patterns for these natural tracers of infiltration. TOC content increased during every recharge period, following the rapid arrival of water infiltrating through the soil. On the other hand, NO3 ? content only rose during the first flood episodes (normally in autumn), and fell during the winter and spring ones. This difference is consequence of the distinctive biogeochemical kinetics of nitrogen with respect to organic carbon, both in the soil and within the aquifer. Unlike the mineralisation undergone by TOC from the surface to the spring, the NO3 ? ion remains in the aquifer almost unaffected, due to the oxidizing conditions prevailing within the karst medium, which do not allow its denitrification and favour its preservation within the saturated zone. In non-polluted aquifers, TOC and NO3 ? have a common origin in the soil and can be used to determine infiltration processes and the hydrogeological functioning of karst aquifers. Their different hydrochemical evolution provides information about mineralization and degradation processes of organic matter within karst aquifers, which can be used to validate the vulnerability to contamination in this type of medium. 相似文献
15.
《Applied Geochemistry》2006,21(1):1-15
Two groups of perennial springs are observed in the Canadian High Arctic at Expedition Fjord on Axel Heiberg Island at Colour Peak and Gypsum Hill. Saline discharge (∼1.3–2.5 molal NaCl) produces a variety of calcite (travertine) and gypsum-rich precipitates. Saturation index calculations of the spring waters at Colour Peak suggest CO2 degassing from the waters causes calcite precipitation. Gypsum precipitation dominates at Gypsum Hill, where spring waters have lower alkalinity and higher SO4 concentrations. Mineral accumulations form both channel and rimstone pool morphologies as a result of varying slope conditions. At Colour Peak, confined flow in steep slope areas develop massive structures in contrast to more friable, porous accumulations in areas where waters fan out on shallower slopes; these morphological variations lead to corresponding varying apparent rates of mineral precipitation. Mineral precipitation at Gypsum Hill is far less notable as a result of lower discharge rates and annual degradation by icing formation. Microscopic observations and geochemical analyses of the channel precipitates at Colour Peak reveal alternating light (calcite spar) and dark (anhedral microcrystalline calcite combined with organic matter and non-carbonate minerals) laminae. Rimstone pools forming in lower sections of spring discharge are composed of accumulations of large euhedral calcite crystals interbedded with allochthonous inputs. High concentration of dissolved solids is responsible for slow travertine precipitation rates, which occurs during winter. This precipitation is further retarded during summer months by the introduction of crystal growth inhibitors such as Fe3+ and deposition of organic matter and soil sediments. 相似文献
16.
Florian Mallet Simon D. Carrière Konstantinos Chalikakis Vincent Marc 《Environmental Earth Sciences》2018,77(13):507
To improve flood prediction in headwater catchments, hydrologists need to know initial soil moisture conditions that precede rain events. In torrential hydrology, soil moisture mapping provides a valuable tool for investigating surface runoff generation processes. In these mountainous environments, soil moisture prediction is challenging because of highly heterogeneous land cover and soil properties. This survey propose a methodology to study spatial soil moisture variations in the mountainous and torrential environment of the Draix Bléone experimental site—Laval 0.86 km2. This approach associates water content measurements at the plot scale with spatialized soil bulk electrical conductivity (ECa) measurements combined in a multivariate statistical analysis based on topographical parameters. Between the summer of 2015 and winter of 2016, four geophysical surveys were conducted under various moisture conditions and along the same pathway, using the Slingram electromagnetic induction (EMI) technique (EM31 device) in horizontal dipole to identify changes in soil properties to a depth of 3 m. These results were analyzed to determine water dynamics in this mountainous catchment. Temporal variations of ECa vary among land cover types (forest, grassland, and black marl). A significant relationship was observed between ECa and soil water content (SWC) measured with capacitive sensors in forest and grassland. A multiple linear regression produced using the spatial interpolation code LISDQS shows a significant correlation between ECa and landform units depicted on a high-resolution DEM. ECa variations decrease with distance to talwegs. Riparian zones appear as potential hydrological contributing areas with patterns varying according to moisture status. This study shows that multiple linear regression analysis and EMI make it possible to fill gaps between SWC plot measurements, over wide areas that are steep and that present numerous obstacles due to vegetation cover. 相似文献
17.
An understanding of the processes that lead to long-term stabilization of organic matter in soils is essential to the effective implementation of strategies designed to mitigate CO2 loss from the soil carbon reservoir in temperate climatic zones. Decomposition studies indicate that montmorillonite, a smectite that often forms with interlayers rich in Ca2+, greatly retards the microbial mineralization of soil organic matter. We performed a series of atomistic simulations designed to identify favorable molecular-scale organo-mineral interactions within nanoscale, hydrated complexes consisting of a humic substance and Ca-montmorillonite. Both protonated and Ca-saturated forms of the model humic molecule, representing acidic and circumneutral solution conditions, respectively, were studied within the hydrated interlayer region of a rigid-atom model of Ca-montmorillonite. The protonated humic substance formed direct hydrophobic and hydrogen bonding (H-bonding) interactions with the clay mineral. A few polar organic groups adsorbed via water bridging interactions. The Ca-saturated humic substance adsorbed via numerous cation bridges, less numerous water bridges, and indirect H-bonding interactions mediated by water molecules. Application of molecular modeling techniques to this complex organo-mineral system thus allowed identification of interactions favorable to carbon sequestration under both acidic and circumneutral conditions. 相似文献
18.
《Chemie der Erde / Geochemistry》2017,77(1):45-52
In this paper we present an elemental and isotopic investigation of carbon and nitrogen in the soil-plant system. Plants grown in an unamended soil were compared to plants grown in a soil amended with natural and NH4+-enriched zeolitites. The aim was to verify that zeolitites at natural state increase the chemical fertilization efficiency and the nitrogen transfer from NH4+-enriched zeolitites to plants. Results showed that plants grown on plots amended with zeolitites have generally a δ15N approaching that of chemical fertilizers, suggesting an enhanced nitrogen uptake from this specific N source with respect to the unamended plot. The δ15N of plants grown on NH4+-enriched zeolitites was strongly influenced by pig-slurry δ15N (employed for the enrichment process), confirming the nitrogen transfer from zeolitites to plants. The different agricultural practices are also reflected in the plant physiology as recorded by the carbon discrimination factor, which generally increases in plots amended with natural zeolitites, indicating better water/nutrient conditions. 相似文献
19.
Benony K. Kortatsi 《Aquatic Geochemistry》2007,13(1):41-74
Hydrochemical and stable isotope (18O and 2H) analyses of groundwater samples were used to establish the hydrochemistry of groundwater in the Ankobra Basin. The groundwater
was generally mildly acidic, low in conductivity and undersaturated with respect to carbonate phases. Major ions except bicarbonate
were low and dissolved silica was moderately high. Silicate minerals weathering is probably the main process through which
major ions enter the groundwater. Groundwater samples clustered tightly along the Global Meteoric Water Line suggesting integrative,
smooth and rapid recharge from meteoric origin. The majority of the boreholes and a few hand dug wells cluster towards the
Ca–Mg–HCO3 dominant section of the phase diagram, in conformity with the active recharge and short residence time shown by the isotope
data. Aluminium, arsenic, manganese, iron and mercury were the only trace metals analysed with concentrations significantly
above their respective detection limits. Approximately 20%, 5%, 40% and 25% respectively of boreholes had aluminium, arsenic,
iron and manganese concentrations exceeding the respective WHO maximum acceptable limits for drinking water. The relatively
large percentage of boreholes with high concentration of aluminium reflects the acidic nature of the groundwater. 相似文献
20.
In order to examine the transportation and deposition mechanisms of Hg, we investigated the ore and hydrothermal alteration minerals and solid organic matters from Itomuka mercury mine located in the eastern part of central Hokkaido. In addition to the ore minerals, native mercury and cinnabar, quartz, marcasite, alunite, kaolinite, and minor amounts of pyrite and smectite were identified in the Hg ore by powder X‐ray diffraction (XRD) analysis. This mineral assemblage of acid sulfate alteration was likely developed under the conditions of low temperature (≤100°C) and low pH (≤2) in the steam‐heated environment. The H2SO4 was produced above the water table by the oxidation of H2S separated from deep, near‐neutral fluids by boiling. The dominance of native mercury over cinnabar in Hg ore indicates that the greater part of mineralized Hg was transported as Hg0 in aqueous solution and vapor with low sulfur fugacity. The solid organic matters found in the Hg ore were analyzed with SEM‐EDS, micro‐XRD, and micro‐Fourier transform infrared (FTIR) spectroscopy, and these results suggest that the organic matters contributed to keeping the low fO2 of the Hg‐bearing fluid and transportation of Hg as Hg0 in S‐poor condition. Because the solubility of Hg in acidic fluid is low, neutral to alkaline fluid seems to have leached Hg from the basement sedimentary rocks of Hidaka Group which also supplied the organic matters to the fluid. The oxidation and cooling of Hg‐bearing solution and vapor triggered the deposition of liquid Hg as a primary phase. 相似文献