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1.
Extensive CO2 vents have been discovered in the Wagner Basin, northern Gulf of California, where they create large areas with lowered seawater pH. Such areas are suitable for investigations of long-term biological effects of ocean acidification and effects of CO2 leakage from subsea carbon capture storage. Here, we show responses of benthic foraminifera to seawater pH gradients at 74–207 m water depth. Living (rose Bengal stained) benthic foraminifera included Nonionella basispinata, Epistominella bradyana and Bulimina marginata. Studies on foraminifera at CO2 vents in the Mediterranean and off Papua New Guinea have shown dramatic long-term effects of acidified seawater. We found living calcareous benthic foraminifera in low pH conditions in the northern Gulf of California, although there was an impoverished species assemblage and evidence of post-mortem test dissolution.  相似文献   

2.
To reduce the negative effect of climate change on Biodiversity, the use of geological CO2 sequestration has been proposed; however leakage from underwater storages may represent a risk to marine life. As extracellular homeostasis is important in determining species’ ability to cope with elevated CO2, we investigated the acid–base and ion regulatory responses, as well as the density, of sea urchins living around CO2 vents at Vulcano, Italy. We conducted in situ transplantation and field-based laboratory exposures to different pCO2/pH regimes. Our results confirm that sea urchins have some ability to regulate their extracellular fluid under elevated pCO2. Furthermore, we show that even in closely-related taxa divergent physiological capabilities underlie differences in taxa distribution around the CO2 vent. It is concluded that species distribution under the sort of elevated CO2 conditions occurring with leakages from geological storages and future ocean acidification scenarios, may partly be determined by quite subtle physiological differentiation.  相似文献   

3.
Carbon capture and storage (CCS) technologies involve localized acidification of significant volumes of seawater, inhabited mainly by planktonic species. Knowledge on potential impacts of these techniques on the survival and physiology of zooplankton, and subsequent consequences for ecosystem health in targeted areas, is scarce. The recent literature has a focus on anthropogenic greenhouse gas emissions into the atmosphere, leading to enhanced absorption of CO2 by the oceans and a lowered seawater pH, termed ocean acidification. These studies explore the effects of changes in seawater chemistry, as predicted by climate models for the end of this century, on marine biota. Early studies have used unrealistically severe CO2/pH values in this context, but are relevant for CCS leakage scenarios. Little studied meso- and bathypelagic species of the deep sea may be especially vulnerable, as well as vertically migrating zooplankton, which require significant residence times at great depths as part of their life cycle.  相似文献   

4.
A mesocosm experiment was conducted to quantify the relationships between the presence and body size of two burrowing heart urchins (Brissopsis lyrifera and Echinocardium cordatum) and rates of sediment nutrient flux. Furthermore, the impact of seawater acidification on these relationships was determined during this 40-day exposure experiment. Using carbon dioxide (CO2) gas, seawater was acidified to pHNBS 7.6, 7.2 or 6.8. Control treatments were maintained in natural seawater (pH ≈ 8.0). Under normocapnic conditions, burrowing urchins were seen to reduce the sediment uptake of nitrite or nitrate whilst enhancing the release of silicate and phosphate. In acidified (hypercapnic) treatments, the biological control of biogeochemical cycles by urchins was significantly affected, probably through the combined impacts of high CO2 on nitrifying bacteria, benthic algae and urchin behaviour. This study highlights the importance of considering biological interactions when predicting the consequences of seawater acidification on ecosystem function.  相似文献   

5.
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6.
The shallow-water hydrothermal system in Tutum Bay on the west side of Ambitle Island, Papua New Guinea provides us with an exceptional opportunity to study isotope systematics in a near shore setting. Compared to seawater, the hydrothermal fluids in Tutum Bay have lower values for δD, δ18O, δ13C, and 87Sr and higher values for 3H, δ34S(SO4) and δ18O(SO4). The δ18O and δD records for vents 1 and 4 indicate that fluid compositions remained stable over an extended period. Interpretation of isotope data clearly demonstrates the predominantly meteoric origin of Tutum Bay hydrothermal fluids, despite their location in a marine environment. δ18O and δD values are identical to mean average annual precipitation in eastern Papua New Guinea. The hypothesis that these fluids are a simple product of mixing between seawater and onshore hydrothermal fluids from the Waramung (W-1) and Kapkai (W-2) thermal areas has been rejected, because the observed δ37Cl, 3H, δ34S(SO4) and δ18O(SO4) values cannot be explained by a simple mixing model. The application of δ18O(SO4) and δ13C thermometers in combination with 3H values corroborates the three-step model of Pichler et al. [Pichler, T., Veizer, J., Hall, G.E.M., 1999. The chemical composition of shallow-water hydrothermal fluids in Tutum Bay, Ambitle Island, Papua New Guinea and their effect on ambient seawater. Marine Chemistry 64 (3) 229–252], where (1) phase separation in the deep reservoir beneath Ambitle Island produces a high temperature vapor that rises upward and subsequently reacts with cooler ground water to form a low pH, CO2-rich water of approximately 150–160 °C, (2) caused by the steep topography, this CO2-rich fluid moves laterally towards the margin of the hydrothermal system where it mixes with the marginal upflow of the deep reservoir fluid. This produces a dilute chloride water of approximately 165 °C, and (3) possibly the entrainment of minor amounts of ground or seawater during its final ascent.  相似文献   

7.
Gas samples were collected from high-temperature, rooted summit vents at Mount St. Augustine in 1979, 1982, and 1984. All of the gas samples exhibit various degrees of disequilibrium. Thermodynamic restoration of the analyzed gases permits partial or complete removal of these disequilibrium effects and allows inference of equilibrium gas compositions. Long-term (1979–1984) degassing trends within resampled or adjacent vents are characterized by increases (from 97.4 to 99.8 mole%) in the H2O fraction and major decreases in the residual gases. Over this same period total gas HCl contents decreased by a factor of 3 to 10 while dry gas (H2O-free recalculated) HCl contents increased by a factor of 1.6 to 3. Dry gas mole proportions at these sites changed from being CO2-dominated (46% CO2, 24% H2 in 1979) to H2-dominated (49% H2, 22% CO2 in 1984). The overall trends in gas chemistry and the stable isotope patterns in gases and condensates from the summit fumaroles can be explained by progressive magmatic outgassing coupled with increasing proportions of seawater in the fumarole emissions.Studies of the gaseous emissions following the 1976 and 1986 Mount St. Augustine eruptions confirmed the Cl- and S-rich nature of the Mount St. Augustine emanations. Seawater, possibly derived from magmatic assimilation or dehydration of near-surface seawater-bearing sediments, could supply a portion of the outgassed Cl and S. Continued seawater influx through subvolcanic fractures or permeable sediments would recharge the seawater-depleted zone and provide a near-surface Cl and S source for the next eruptive cycle,Various lines of evidence support a phreatomagmatic component in the 1976 and 1986 Mount St. Augustine eruptions. We suggest that seawater may interact with magma or volcanic gases during the early explosive phase of Mount St. Augustine eruptions and that it continues to influence high-temperature fumarole emissions as the volcanic system cools.  相似文献   

8.
13C and ΣCO2 data from the North and South Atlantic, the Antarctic, and the North and South Pacific are given. The δ13C of the ΣCO2 in the deep water (～3000m) decreases from 1.7‰ in the North Atlantic to ?0.10‰ in the North Pacific. This change is attributed to the addition of about 158 μmoles of CO2 per kg of seawater. The in-situ oxidation of organic matter accounts for 83% of this increase in ΣCO2, while the remainder is attributed to dissolution of calcium carbonate.The δ13C of the dissolved CO2 in mid-latitude surface water samples is controlled by a quasi-steady-state equilibrium with atmospheric CO2 at a mean temperature of 16°C. The δ13C and ΣCO2 values of Antarctic surface water samples suggest that these waters are derived from a mixture of North Atlantic deep water and equilibrated surface water.  相似文献   

9.
The CO2 and H2S concentration in the Solfatara atmosphere has been measured. The concentrations of both gases are higher neraby the more active areas and decrease away from them. A sharp horizontal and vertical gradient of the CO2 content has been recognized.Such gradient is assumed to result from a diffusion of gas from the ground to the atmosphere.The total output of CO2 has been computed based on a turbulent diffusion model. The obtained value is in good agreement with previously abserved values (Italiano et al., 1984).The feasibility of monitoring the atmosphere of Solfatara for either gas hazard and surveillance of volcanic activity has also been evaluated.  相似文献   

10.
Discharge from subaereal and submarine gas vents of the Baia di Levante beach gases from the Vulcano Island were sampled for major and trace gas components in May and November 1995.Chemical compositions and equilibrium calculations suggest three different groups of CO2-rich gas emissions depending on their distance from the La Fossa crater: (1) gas vents close to the Faraglione area are characterised by high H2S contents, high calculated equilibrium temperatures based on inorganic species and relatively high proportion of alkene compounds; (2) gas vents close to Vulcanello are characterised by low calculated equilibrium temperatures and low amounts of alkenes; and (3) Pontile sample has the highest equilibrium CO2 pressure (up to 68 bars) which may account for the observed absence of benzene. The relative large variability of H2S in the Baia di Levante beach gas discharge may be attributed to either different interactions between iron sulphides and weakly acid waters or catalytic effect of elemental sulphur on the de-hydrogenation of cyclo-hexane. Thermodynamic calculations suggest that the main inorganic species and CH4 may have re-equilibrated at relatively shallow depth (10–200 m b.s.l. and 30–600 m b.s.l. for a lithostatic and hydrostatic pressure, respectively). The slow kinetics of reactions in the CnH2n/CnH2n+2 systems, with respect to that of CH4–CO–CO2, may explain the observed propene/propane ratios, which can only be reached at reaction temperatures of 300–350°C. This low speed of reactions can also explain the observed disequilibrium of C1–C4 alkanes.  相似文献   

11.
We estimated the net annual air–sea exchange of carbon dioxide (CO2) using monitoring data from the East Gotland Sea, Bornholm Sea, and Kattegat for the 1993–2009 period. Wind speed and the sea surface partial pressure of CO2 (pCO2w), calculated from pH, total alkalinity, temperature, and salinity, were used for the flux calculations. We demonstrate that regions in the central Baltic Sea and the Kattegat alternate between being sinks (−) and sources (+) of CO2 within the −4.2 to +5.2 mol m−2 yr−1 range. On average, for the 1994–2008 period, the East Gotland Sea was a source of CO2 (1.64 mol m−2 yr−1), the Bornholm Sea was a source (2.34 mol m−2 yr−1), and the Kattegat was a sink (−1.16 mol m−2 yr−1). Large inter-annual and regional variations in the air–sea balance were observed. We used two parameterizations for the gas transfer velocity (k) and the choice varied the air–sea exchange by a factor of two. Inter-annual variations in pCO2w between summers were controlled by the maximum concentration of phosphate in winter. Inter-annual variations in the CO2 flux and gas transfer velocity were larger between winters than between summers. This indicates that the inter-annual variability in the total flux was controlled by winter conditions. The large differences between the central Baltic Sea and Kattegat were considered to depend partly on the differences in the mixed layer depth.  相似文献   

12.
A dynamic method suitable for shipboard measurement of the partial pressure of CO2 exerted by a seawater sample has been developed. The system consists of a paddle-wheel-type gas-water equilibrator and an infrared gas analyzer. Since the system is open to the atmosphere at the in-take and the exhaust ends, it can be operated stably on shipboard conditions. A precision of ±2% has been obtained for shipboard measurement of pCO2.  相似文献   

13.
Some planktonic groups suffer negative effects from ocean acidification (OA), although copepods might be less sensitive. We investigated the effect of predicted CO2 levels (range 480–750 ppm), on egg production and hatching success of two copepod species, Centropages typicus and Temora longicornis. In these short-term incubations there was no significant effect of high CO2 on these parameters. Additionally a very high CO2 treatment, (CO2 = 9830 ppm), representative of carbon capture and storage scenarios, resulted in a reduction of egg production rate and hatching success of C. typicus, but not T. longicornis. In conclusion, reproduction of C. typicus was more sensitive to acute elevated seawater CO2 than that of T. longicornis, but neither species was affected by exposure to CO2 levels predicted for the year 2100. The duration and seasonal timing of exposures to high pCO2, however, might have a significant effect on the reproduction success of calanoid copepods.  相似文献   

14.
In the Tyrrhenian region of central Italy, late Quaternary fossil travertines are widespread along two major regional structures: the Tiber Valley and the Ancona-Anzio line. The origin and transport of spring waters from which travertines precipitate are elucidated by chemical and isotopic studies of the travertines and associated thermal springs and gas vents. There are consistent differences in the geochemical and isotopic signatures of thermal spring waters, gas vents and present and fossil travertines between east and west of the Tiber Valley. West of the Tiber Valley, δ13C of CO2 discharged from gas vents and δ13C of fossil travertines are higher than those to the east. To the west the travertines have higher strontium contents, and gases emitted from vents have higher 3He/4He ratios and lower N2 contents, than to the east. Fossil travertines to the west have characteristics typical of thermogene (thermal spring) origin, whereas those to the east have meteogene (low-temperature) characteristics (including abundant plant casts and organic impurities). The regional geochemical differences in travertines and fluid compositions across the Tiber Valley are interpreted with a model of regional fluid flow. The regional Mesozoic limestone aquifer is recharged in the main axis of the Apennine chain, and the groundwater flows westward and is discharged at springs. The travertine-precipitating waters east of the Tiber Valley have shallower flow paths than those to the west. Because of the comparatively short fluid flow paths and low (normal) heat flow, the groundwaters to the east of the Tiber Valley are cold and have CO2 isotopic signatures, indicating a significant biogenic contribution acquired from soils in the recharge area and limited deeply derived CO2. In contrast, spring waters west of the Tiber Valley have been conductively heated during transit in these high heat-flow areas and have incorporated a comparatively large quantity of CO2 derived from decarbonation of limestone. The elevated strontium content of the thermal spring water west of the Tiber Valley is attributed to deep circulation and dissolution of a Triassic evaporite unit that is stratigraphically beneath the Mesozoic limestone. U-series age dates of fossil travertines indicate three main periods of travertine formation (ka): 220-240, 120-140 and 60-70. Based on the regional flow model correlating travertine deposition at thermal springs and precipitation in the recharge area, we suggest that pluvial activity was enhanced during these periods. Our study suggests that travertines preserve a valuable record of paleofluid composition and paleoprecipitation and are thus useful for reconstructing paleohydrology and paleoclimate.  相似文献   

15.
Ten samples were recovered by the submersible “Cyana” submersible from two groups of hydrothermal vents located 2600 m deep along the East Pacific Rise at 13°N. The maximum measured temperature was 317°C and minimum pH 3.8. A systematic determination of major and trace elements has been carried out and mixing lines between a high-temperature component (HTC) and seawater are observed. The water chemistry of the HTC slightly differs for several elements at the two sites. This HTC is deprived of SO4 and Mg and is greatly enriched in most other species. Maximum concentrations are (in units per kg):Cl = 0.72mol; Br = 1.1mmol; Na = 0.55mol; K = 29mmol; Rb = 14 μmol; Ca = 52mmol; Sr = 170 μmol; Mn = 750 μmol; Fe = 1mmol; Al = 15 μmol; Si = 21mmol. For many elements, the magnitude of the anomaly relative to seawater does not compare with the results obtained from the Galapagos or East Pacific Rise 21°N. The enrichment of cations relative to seawater is likely related to the huge Cl excess through charge balance. TheBr/Cl ratio is close to that for seawater. However, it is not clear whether the Cl excess is due to gas release or basalt hydration (formation of amphibole chlorite or epidote).P-T dependence of SiO2 solubility suggests that water-rock interaction last occurred at a depth in excess of 1 km below the sea floor. A mixing line of87Sr/86Sr vs. Mg/Sr demonstrates that the HTCs have a nearly identical87Sr/86Sr ratio of 0.7041 for both sites. A water/rock ratio of about 5 is inferred, which differs from the 1.5 value obtained at 21°N.  相似文献   

16.
Iwojima volcano, located on the southernmost part of the Izu-Ogasawara arc, is characterized by the extrusion of trachyte or trachy andesite lavas and pyroclastic rocks of Holocene and surface thermal manifestations. Small phreatic explosions have been recorded frequently during the last 100 years with the most recent in 1999 and 2001. In order to elucidate the behavior of volcanic volatiles and to assess the potential activity of this volcano, diffuse CO2 efflux, CO2 content and δ13C–CO2 in soil gas, and soil temperature at 30 cm depth were measured at 272 sites in March 2000, 112 sites in December 2000 and 40 sites in December 2001. We found that high CO2 efflux values, of more than 100 g m−2 day−1, occurred at several locations on Motoyama volcano corresponding with high soil temperatures (more than 60 °C at 30 cm depth) region and with areas where CO2 with magmatic δ13C was observed. Here, the magmatic δ13C determined for fumarolic CO2 data ranged from −2‰ to +3‰, which is clearly higher than magmatic gas values (−8‰ to −2‰) typically found in island arc settings around the world. However, this can be explained in terms of carbon-isotope fractionation between calcite and CO2 under subsurface temperature and pressure conditions at Iwojima. A total efflux of CO2 for Iwojima volcano is estimated to be 760 t day−1, with a magmatic contribution of about 450 t day−1. This value is rather high compared with other volcanoes in island arc settings. Since Iwojima has no visible plume, almost all volcanic CO2 is released as diffuse efflux through the volcanic edifice.  相似文献   

17.
A laboratory inorganic carbonate precipitation experiment at high pH of 8.96 to 9.34 was conducted, and the boron isotopic fractionations of the precipitated carbonate were measured. The data show that boron isotopic fractionation factors (αcarb-3) between carbonate and B(OH)3 in seawater range 0.937 and 0.965, with an average value of 0.953. Our results together with those reported by Sanyal and collaborators show that the αcarb-3 values between carbonate and B(OH)3 in solution are not constant but are negatively correlated with the pH of seawater. The measured boron isotopic compositions of carbonate precipitation (δ11Bcarb) do not exactly lie on the best-fit theoretical δ11B4-pH curves and neither do they exactly parallel any theoretical δ11B4-pH curves. Therefore, it is reasonable to argue that a changeable proportion of B(OH)3 with pH of seawater should also be incorporated into carbonate except for the dominant incorporation of B(OH)4 − in carbonate. Hence, in the reconstruction of the paleo-pH of seawater from boron isotopes in marine biogenic carbonates, the use of theoretical boron isotopic fractionation factor (α4−3) between B(OH)4 − and B(OH)3 is not suitable. Instead, an empirical equation should be established. Supported by National Natural Science Foundation of China (Nos. 40573013 and 40776071), State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences (Grant No SKLLQG0502) and State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences  相似文献   

18.
Data on the distribution of fCO2 were obtained during a cruise in the Aegean Sea during February 2006. The fCO2 of surface water (fCO2sw) was lower than the atmospheric fCO2 (fCO2atm) throughout the area surveyed and ΔfCO2 values varied from ?34 to ?61 μatm. The observed under-saturation suggests that surface waters in the Aegean represent a sink for atmospheric CO2 during the winter of 2006. Higher fCO2sw values were recorded in the ‘less warm’ and ‘less saline’ shallow northernmost part of the Aegean Sea implying that the lower seawater temperature and salinity in this area play a crucial role in the spatial distribution of fCO2sw.A first estimate of the magnitude of the air–sea CO2 exchange and the potential role of the Aegean Sea in the transfer of atmospheric CO2 was also obtained. The air–sea CO2 fluxes calculated using different gas transfer formulations showed that during February 2006, the Aegean Sea absorbs atmospheric CO2 at a rate ranging from ?6.2 to ?11.8 mmol m?2 d?1 with the shipboard recorded wind speeds and at almost half rate (?3.5 to ?5.5 mmol m?2 d?1) with the monthly mean model-derived wind speed. Compared to recent observations from other temperate continental shelves during winter period, the Aegean Sea acts as a moderate to rather strong sink for atmospheric CO2.Further investigations, including intensive spatial and temporal high-resolution observations, are necessary to elucidate the role of the Aegean Sea in the process of transfer of atmospheric CO2 into the deep horizons of the Eastern Mediterranean.  相似文献   

19.
Wide variations were measured in the diffuse CO2 flux through the soils in three selected areas of Mt Etna between August 1989 and March 1993. Degassing of CO2 from the area of Zafferana Etnea-S. Venerina, on the eastern slope of the volcano, has been determined to be more strongly influenced by meteorological parameters than the other areas. The seasonal component found in the data from this area has been excluded using a filtering algorithm based on the best fitting equation calculated from the correlation between CO2 flux values and those of air temperature. The filtered data appear to have variations temporally coincident with those from the other areas, thus suggesting a common and probably deep source of gas. The highest fluxes measured in the two most peripheral areas may correlate well with other geophysical and volcanological anomalous signals that preceded the strong eruption of 1991–1993 and that were interpreted as deep pressure increases. Anomalous decreases in CO2 fluxes accompanied the onset and the evolution of that eruption and have been interpreted as a sign of upward migration of the gas source. The variations of CO2 flux at the 1989 SE fracture have also given interesting information on the timing of the magmatic intrusion that has then fed the 1991–1993 eruption.  相似文献   

20.
In the Jungwon area, South Korea, two contrasting types of deep thermal groundwater (around 20–33 °C) occur together in granite. Compared to shallow groundwater and surface water, thermal groundwaters have significantly lower δ18O and δD values (> 1‰ lower in δ18O) and negligible tritium content (mostly < 2 TU), suggesting a relatively high age of these waters (at least pre-thermonuclear period) and relatively long subsurface circulation. However, the hydrochemical evolution yielded two distinct water types. CO2-rich water (PCO2 = 0.1 to 2 atm) is characterized by lower pH (5.7–6.4) and higher TDS content (up to 3300 mg/L), whereas alkaline water (PCO2 = 10− 4.1–10− 4.6 atm) has higher pH (9.1–9.5) and lower TDS (< 254 mg/L). Carbon isotope data indicate that the CO2-rich water is influenced by a local supply of deep CO2 (potentially, magmatic), which enhanced dissolution of silicate minerals in surrounding rocks and resulted in elevated concentrations of Ca2+, Na+, Mg2+, K+, HCO3− and silica under lower pH conditions. In contrast, the evolution of the alkaline water was characterized by a lesser degree of water–rock (granite) interaction under the negligible inflow of CO2. The application of chemical thermometers indicates that the alkaline water represents partially equilibrated waters coming from a geothermal reservoir with a temperature of about 40 °C, while the immature characteristics of the CO2-rich water resulted from the input of CO2 in Na–HCO3 waters and subsequent rock leaching.  相似文献   

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