Solubility of calcite in the ocean     

S. E. Ingle 《Marine Chemistry》1975,3(4):301-319

The apparent solubility product K′_sp of calcite in seawater was measured as a function of temperature, salinity, and pressure using potentiometric saturometry techniques. The temperature effect was hardly discernible experimentally. The value of K′_sp at 25°C was 4.59·10⁻⁷ mole²/(kg seawater)² at 35‰S, 5.34·10⁻⁷ at 43‰S, and 3.24·10⁻⁷ at 27‰S. The apparent partial molal volume was found to be −34.4 cm³ at 25°C and −42.3 cm³ at 2°C from a linear fit of log(K′_sp ^P/K′_sp ¹). These results were used in conjunction with field data to calculate the degree of saturation in the oceans and showed undersaturation at shallower depths than previously reported.  相似文献   

Thermodynamic studies of the carbonate system in seawater     

Kitack Lee  Frank J. Millero   《Deep Sea Research Part I: Oceanographic Research Papers》1995,42(11-12)

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The solubility of calcite in seawater at atmospheric pressure and 35%permil; salinity     

S.E. Ingle  C.H. Culberson  J.E. Hawley  R.M. Pytkowicz 《Marine Chemistry》1973,1(4):295-307

The apparent (stoichiometric) solubility product of calcite in artificial seawater of salinity 35‰ was measured by a saturometer technique. The value of the apparent solubility product was found to be (4·59 ± 0·05) × 10⁻⁷ moles/(kilogram of seawater)² at 25°C with a temperature coefficient of −0·0108 × 10⁻⁷/°C between 2 and 25°C. These values are significantly smaller than those found by MacIntyre (1965) and other workers. The effect of these results on the saturation of the oceans with respect to calcite is examined.  相似文献   

Distribution coefficient of Mg ions between calcite and solution at 10–50°C     

Tamotsu Oomori  Hiroshi Kaneshima  Yoko Maezato  Yasushi Kitano   《Marine Chemistry》1987,20(4)

The distribution coefficient (λ_Mg) of Mg²⁺ ions between calcite and solution was found to be 0.012 ± 0.001 (10°C), 0.014 ± 0.001 (15°C), 0.019 ± 0.001 (25°C), 0.024 ± 0.001 (30°C), 0.027 ± 0.001 (35°C) and 0.040 + 0.003 (50°C). This indicates a remarkable dependence on temperature. The effect of the Mg²⁺/Ca²⁺ molar ratio in a parent solution on λ_Mg for calcite is small, where the molar ratio lies in the range 0.04-2. However, the λ_Mg value for aragonite tends to decrease with increasing Mg²⁺/Ca²⁺ ratio in the parent solution. The largest Mg content of calcite in the Ca(HCO₃)₂-Mg²⁺ → calcite system is around 2 mol% in the temperature range 10–50°C. Neither homogeneous nor heterogeneous distribution laws hold for aragonite precipitation, and the temperature effect on the coprecipitation of Mg²⁺ ions with aragonite is very small.  相似文献   

The distribution and population dynamics of O-group plaice (Pleuronectes platessa L.) on nursery grounds in the Firth of Forth     

M. G. Poxton  N. A. Nasir 《Estuarine, Coastal and Shelf Science》1985,21(6):845-857

Midsummer (1 August) population estimates of about 2 million O-group plaice (Pleuronectes platessa L.) were derived for sandy bays around the Firth of Forth in 1979–1980. This is an order of magnitude less than similar estimates made for the Clyde Sea Area in 1973–1974. Autumn population estimates of 0·4–1·0 million fish were comparable to estimates by the Ministry of Agriculture, Fisheries and Food for the area between the Scottish border and Flamborough Head (2·3 million for 1970 and 1973) which represented 4·8% (1973) to 5·3% (1970) of the total number of O-group fish on the English east coast.Largo Bay was the most important nursery area holding 25% of the total population. It is particularly well situated to receive newly metamorphosed plaice carried in water currents along the north side of the Forth from the spawning ground off Fife Ness. Plaice in the Forth are mainly distributed on fine to medium sandy beaches (186–480 μm), the mean number per haul in midsummer (D) being correlated with the median diameter (m.d. in μm) of the low water sediments by the equation: D=−45·7666+0·2327 m.d. (n=11,r=0·68,P<0·02 but>0·01).The shallow inshore water in sandy bays in the outer Firth was well mixed and more marine than estuarine (27·7–35·0‰). The correlation coefficient between fish density and water temperature was low, while that with salinity (S‰) was: D=6·1618+0·2238S (n=23,r=0·62,P<0·005).Regression analysis demonstrated that the relationship between the instantaneous mortality rate (Z) and the initial population density (D_p) was: Z×100=0·7480+0·0546d_p (n=12,r=0·87,P<0·001).The mean mortality rate for the O-group plaice in the Forth nursery areas was 53% month⁻¹.  相似文献   

A seasonal carbon budget for the sub-Antarctic Ocean, South of Australia     

B.I. McNeil  B. Tilbrook 《Marine Chemistry》2009,115(3-4):196-210

Changes from winter (July) to summer (February) in mixed layer carbon tracers and nutrients measured in the sub-Antarctic zone (SAZ), south of Australia, were used to derive a seasonal carbon budget. The region showed a strong winter to summer decrease in dissolved inorganic carbon (DIC;  45 µmol/kg) and fugacity of carbon dioxide (fCO₂;  25 µatm), and an increase in stable carbon isotopic composition of DIC (δ¹³C_DIC;  0.5‰), based on data collected between November 1997 and July 1999.The observed mixed layer changes are due to a combination of ocean mixing, air–sea exchange of CO₂, and biological carbon production and export. After correction for mixing, we find that DIC decreases by up to 42 ± 3 µmol/kg from winter (July) to summer (February), with δ¹³C_DIC enriched by up to 0.45 ± 0.05‰ for the same period. The enrichment of δ¹³C_DIC between winter and summer is due to the preferential uptake of ¹²CO₂ by marine phytoplankton during photosynthesis. Biological processes dominate the seasonal carbon budget (≈ 80%), while air–sea exchange of CO₂ (≈ 10%) and mixing (≈ 10%) have smaller effects. We found the seasonal amplitude of fCO₂ to be about half that of a study undertaken during 1991–1995 [Metzl, N., Tilbrook, B. and Poisson, A., 1999. The annual fCO₂ cycle and the air–sea CO₂ flux in the sub-Antarctic Ocean. Tellus Series B—Chemical and Physical Meteorology, 51(4): 849–861.] for the same region, indicating that SAZ may undergo significant inter-annual variations in surface fCO₂. The seasonal DIC depletion implies a minimum biological carbon export of 3400 mmol C/ m² from July to February. A comparison with nutrient changes indicates that organic carbon export occurs close to Redfield values (ΔP:ΔN:ΔC = 1:16:119). Extrapolating our estimates to the circumpolar sub-Antarctic Ocean implies a minimum organic carbon export of 0.65 GtC from the July to February period, about 5–7% of estimates of global export flux. Our estimate for biological carbon export is an order of magnitude greater than anthropogenic CO₂ uptake in the same region and suggests that changes in biological export in the region may have large implications for future CO₂ uptake by the ocean.  相似文献   

Toxicological effects of potash brine on bay of Fundy marine organisms     

Michael S. Hutcheson 《Marine environmental research》1983,9(4):237-255

The acute lethality and sublethal heavy metal contamination potential to marine organisms of a waste brine solution from a potash mining operation were determined. The brine was acutely lethal to marine organisms of the Bay of Fundy, Canada, at concentrations between 47 and 55‰ salinity (96-h LC₅₀ values: threespine stickleback, Gasterosteus aculeatus, 47·7‰; polychaete worm, Nephtys incisa, 52·5‰; blue mussel, Mytilus edulis, lethal to whole animal and reduced ciliary activity of gills above 55‰).The brine diluted to sublethal concentrations (≤40‰) contained manganese (≤ 49·5 ×), copper and zinc (≤ 5·2 ×), lead (≤ 2·6 ×) and cadmium (≤ 0·7 ×) in decreasing order of enrichment relative to control seawater. Copper was accumulated in mussels exposed to these solutions over 44 days to the greatest degree (4 ·4 ×), followed by manganese and lead. Tissue lead concentration reached a steady value within 44 days and cadmium was not accumulated.  相似文献   

Induction of heat shock protein (hsp)60 in Isochrysis galbana exposed to sublethal preparations of dispersant and Prudhoe Bay crude oil     

M. F. Wolfe  H. E. Olsen  K. A. Gasuad  R. S. Tjeerdema  M. L. Sowby 《Marine environmental research》1999,47(5):517

Adaptation to sublethal exposure to crude oil by phytoplankton is poorly understood. Use of chemical dispersants for oil spill remediation increases petroleum hydrocarbon concentrations in water, while exposing marine organisms to potentially toxic concentrations of dispersant. Heat shock proteins (hsps) have been found to serve as an adaptive and protective mechanism against environmental stresses. The objective of this project was to examine the induction of hsps in Isochrysis galbana, a golden-brown algae, following exposure to the water-accommodated fraction (WAF) of Prudhoe Bay crude oil (PBCO) and PBCO chemically dispersed with Corexit 9527® (dispersed oil: DO). Initial experiments using ³⁵S-labeled amino acids and 2-dimensional electrophoresis with subsequent western blotting identified and confirmed hsp60, a member of the chaperonin family of stress proteins, as being efficiently induced by heat shock in this species. One-dimensional SDS PAGE and western blotting, with hsp60 antibodies and chemiluminesence detection, were used to quantitate hsp60 following exposure to a range of environmental temperatures and concentrations of WAF and DO preparations. I. galbana cultured in 22 parts per thousand (‰) salinity showed a statistically significant increase (p<0.05) in hsp60 after exposure to 25, 30, and 35°C for 1 h compared to controls (20°C), while 34‰ cultures showed no significant increase in hsp60 with increasing temperature. Cultures (22 and 34‰) exposed to varying doses of WAF and DO exhibited statistically significant (p<0.05) increases in levels of hsp60 in all cases. A dose-related response was observed in all exposures (r²≥0.90) with the exception of 34‰ WAF. In independent exposures, a dose-related hsp60 response to naphthalene, a relatively abundant water-soluble aromatic hydrocarbon, was observed in both 22 and 34‰ cultures. Results of this study are consistent with previous studies in other species documenting increases in hsp60 levels with exposure to xenobiotics. Further studies are investigating the protective function of hsp60 against the toxic effects of exposure to WAF and DO preparations.  相似文献   

Seasonal and interannual variability of the air–sea CO₂ flux in the Atlantic sector of the Barents Sea     

Abdirahman M. Omar  Truls Johannessen  Are Olsen  Staffan Kaltin  Francisco Rey 《Marine Chemistry》2007,104(3-4):203-213

The seasonal and interannual variability of the air–sea CO₂ flux (F) in the Atlantic sector of the Barents Sea have been investigated. Data for seawater fugacity of CO₂ (fCO₂^sw) acquired during five cruises in the region were used to identify and validate an empirical procedure to compute fCO₂^sw from phosphate (PO₄), seawater temperature (T), and salinity (S). This procedure was then applied to time series data of T, S, and PO₄ collected in the Barents Sea Opening during the period 1990–1999, and the resulting fCO₂^sw estimates were combined with data for the atmospheric mole fraction of CO₂, sea level pressure, and wind speed to evaluate F.The results show that the Atlantic sector of the Barents Sea is an annual sink of atmospheric CO₂. The monthly mean uptake increases nearly monotonically from 0.101 mol C m^− 2 in midwinter to 0.656 mol C m^− 2 in midfall before it gradually decreases to the winter value. Interannual variability in the monthly mean flux was evaluated for the winter, summer, and fall seasons and was found to be ± 0.071 mol C m^− 2 month^− 1. The variability is controlled mainly through combined variation of fCO₂^sw and wind speed. The annual mean uptake of atmospheric CO₂ in the region was estimated to 4.27 ± 0.68 mol C m^− 2.  相似文献   

The reliability of the thermodynamic constants for the dissociation of carbonic acid in seawater     

Kitack Lee  Frank J. Millero  Douglas M. Campbell 《Marine Chemistry》1996,55(3-4)

Laboratory measurements of all four CO₂ parameters [f_CO2 ( = fugacity of CO₂), pH, TCO₂ ( = total dissolved inorganic carbon), and TA ( = total alkalinity)] were made on the same sample of Gulf Stream seawater (S = 35) as a function of temperature (5–35 °C) and the ratio of TA/TCO₂ (X) (1.0–1.2). Overall the measurements were consistent to ±8 μ atm in f_CO2, ± 0.004 in pH, ± 3 μ mol kg⁻¹ in TCO₂, and ± 3 μ mol kg⁻¹ in TA with the thermodynamic constants of Goyet and Poisson (1989), Roy et al. (1993), and Millero (1995). Deviations between the measured pH, TCO₂, TA and those calculated from various input combinations increase with increasing X when the same constants are used. This trend in the deviations indicates that the uncertainties in pK₂ become important with increasing X (surface waters), but are negligible for samples with the lower X (deep waters). This trend is < 5 μ mol kg⁻¹ when the pK₂ values of Lee and Millero (1995) are used.The overall probable error of the calculated f_CO2 due to uncertainties in the accuracy of the parameters (pH, TCO₂, TA, pK₀, pk₁, and pK₂) is ± 1.2%, which is similar to the differences between the measured values and those calculated using the thermodynamic constants of Millero (1995).The calculated values of pK₁, (from f_CO2-TCO₂-TA) agree to within ± 0.004 compared to the results of Dickson and Millero (1987), Goyet and Poisson (1989), Roy et al. (1993), and Millero (1995) over the same experimental conditions. The calculated values of pK₂ (from pH-TCO₂-TA) are in good agreement (± 0.004) with the results of Lee and Millero (1995) and also in reasonable agreement (± 0.008) with the results of Goyet and Poisson (1989), Roy et al. (1993), and Millero (1995). The salinity dependence of our derived values of pK₁ and pK₂, (S = 35) can be estimated using the equations determined by Millero (1995).  相似文献   

Methane-dominated thermochemical sulphate reduction in the Triassic Feixianguan Formation East Sichuan Basin, China: towards prediction of fatal H₂S concentrations   总被引：2，自引：0，他引：2  

Chunfang Cai  Zengye Xie  Richard H. Worden  Guoyi Hu  Lansheng Wang  Hong He 《Marine and Petroleum Geology》2004,21(10):1265-1279

New sour pools have recently found in the Lower Triassic Feixianguan Fm carbonate reservoirs in the East Sichuan Basin in China with H₂S up to 17.4% by volume. A recent blowout from a well drilled into this formation killed hundreds of people as a result of the percentage concentrations of H₂S. In order to assess the origin of fatal H₂S as well as the cause of petroleum alteration, H₂S concentrations and the isotopes, δ³⁴S and δ¹³C have been collected and measured in gas samples from reservoirs. Anhydrite, pyrite and elemental sulphur δ³⁴S values have been measured for comparison. The high concentrations of H₂S gas are found to occur at depths >3000 m (temperature now at 100 °C) in evaporated platform facies oolitic dolomite or limestone that contains anhydrite nodule occurrence within the reservoirs. Where H₂S concentrations are greater than 10% its δ³⁴S values lie between +12.0 and +13.2‰ CDT. This is within the range of anhydrite δ³⁴S values found within the Feixianguan Fm (+11.0 to +21.7‰; average 15.5±3.5‰ CDT). Thus H₂S must have been generated by thermochemical sulphate reduction (TSR) locally within the reservoirs. Burial history analysis and fluid inclusion data reveal that the temperature at which TSR occurred was greater than about 130–140 °C, suggesting that the present depth-temperature minimum is an artifact of post-TSR uplift. Both methane and ethane were actively involved in TSR since the petroleum became almost totally dry (no alkanes except methane) and methane δ¹³C values become significantly heavier as TSR proceeded. Methane δ¹³C difference thus reflects the extent of TSR. While it is tempting to use a present-day depth control (>3000 m) to predict the distribution of H₂S in the Feixianguan Fm, this is an invalid approach since TSR occurred when the formation was buried some 1000–2000 m deeper than it is at present. The likelihood of differential uplift across the basin means that it is important to develop a basinal understanding of the thermal history of the Feixianguan Fm so that it is possible to determine which parts of the basin have been hotter than 130–140 °C.  相似文献   

Spectrophotometric pH measurement in estuaries using thymol blue and m-cresol purple     

Luke M. Mosley  Shamus L.G. Husheer  Keith A. Hunter   《Marine Chemistry》2004,91(1-4):175-186

The conditional acid dissociation constants (pK_a′) of two sulfonephthalein dyes, thymol blue (TB) and m-cresol purple (mCP), were assessed throughout the estuarine salinity range (0<S<40) using a tris/tris–HCl buffer and spectrophotometric measurement. The salinity dependence of the pK_a′ of both dyes was fitted to the equations (25 °C, total proton pH scale, mol kg soln⁻¹):The estimated accuracy of pH measurements using these calculated pK_a′ values is considered to be comparable to that possible with careful use of a glass electrode (±0.01 pH unit) but spectrophotometric measurements in an estuary have the significant advantage that it is not necessary to calibrate an electrode at different salinities. pH was measured in an estuary over a tidal cycle with a precision of ±0.0005 pH unit at high (S>30) salinity, and ±0.002 pH unit at low (S<5) salinity. The pH increased rapidly in the lower salinity ranges (0<S<15) but less rapidly at higher salinities.  相似文献   

Diffusion coefficients of major ions in seawater     

A. Poisson  A. Papaud 《Marine Chemistry》1983,13(4):265-280

Self-diffusion coefficients of five major ions have been determined by a radioactive tracer method (capillary tube method) in seawater of salinity 34.86 at 25°C. Data are presented for Na⁺, Ca²⁺, Cl⁻, SO₄², and HCO₃⁻, which constitute about 95% by weight of sea salt. The influence of temperature and salinity on these coefficients has been studied for Na⁺ and Cl⁻ which are the major components of sea salt: self-diffusion coefficients of these two ions have been measured in seawater, at different temperatures for a salinity of 34.86 and at different salinities for a temperature of 25°C. Diffusion coefficients of the same ions have been determined at 25°C by using another radioactive tracer method (quasi-steady cell method). In this experiment, seawater ions were allowed to diffuse from natural seawater into dilute seawater. Data have been obtained at 25°C for Na⁺, Ca ²⁺, Cl⁻, SO₄²⁻ and HCO₃⁻, corresponding to different salinity gradients.  相似文献   

Modelling the monthly sea surface f_CO2 fields in the Indian Ocean     

Ferial Louanchi  Nicolas Metzl  Alain Poisson 《Marine Chemistry》1996,55(3-4)

In order to construct monthly fields of sea surface fugacity of carbon dioxide (f_CO2) on a large scale in the Indian Ocean, we use a one-dimensional model which takes into account the main physical and biogeochemical processes controlling f_CO2 variations in the ocean. Physical and biogeochemical processes are constrained by the monthly variations of sea surface temperature, salinity, chlorophyll concentration, wind speed and mixed-layer depth. The model is applied to four locations in the Indian Ocean and it well predicts observed temporal variations in f_CO2 at these locations. Regarding to monthly f_CO2 observations, the model also well simulates the f_CO2 distribution and its temporal variations along a track located between 20 ° and 50 °S with a maximal error of + 10 μatm. The model is also used to predict f_CO2 for 2 ° × 2 ° grids over the entire Indian Ocean and simulates seasonal cycles that are consistent with observations. The monthly f_CO2 fields derived from the model are used to estimate a global air-sea CO₂ flux over the Indian Ocean basin. We estimate a net sink of 0.5 Gt/yr C for the Indian Ocean (20 °N-50 °S), with the main sink located between 20 ° and 50 °S.  相似文献   

Daily variability of dissolved inorganic radiocarbon in Sargasso Sea surface water     

Kelsey McDuffee  Ellen R.M. Druffel   《Marine Chemistry》2007,106(3-4):510-515

Surface water samples were collected daily in June 2000 at a site in the Sargasso Sea to observe variability of Δ¹⁴C values in dissolved inorganic carbon (DIC). Temperature, salinity, DIC concentration, alkalinity, and δ¹³C and Δ¹⁴C values of DIC were measured in the samples. Ten Δ¹⁴C measurements averaged 81 ± 8‰ and had a range of 24‰ over the sixteen-day cruise. Δ¹⁴C values were more variable during the latter half of the cruise. Salinity and temperature measurements in the mixed layer throughout the cruise indicate that there were changes in water mass that occurred at our site. We conclude that the daily range of DIC Δ¹⁴C values in the surface ocean at our site is several times greater than the annual change in surface waters in the Sargasso Sea during the last two decades of the 20th century. This points to the importance of obtaining multiple measurements of the surface ocean to adequately define the true variability of DIC Δ¹⁴C measurements.  相似文献   

Determination of Henry's law constants for hexachlorocyclohexanes in distilled water and artificial seawater as a function of temperature     

John R. Kucklick  Daniel A. Hinckley  Terry F. Bidleman   《Marine Chemistry》1991,34(3-4)

Henry's law constants were determined for α- and γ-hexachlorocyclohexane (HCH) as a function of temperature (0.5–45°C) in artificial seawater (SW; 30‰) and distilled water (DW) using the gas stripping method. Water samples (1–5 ml) were withdrawn from the stripping vessel during the stripping process (30–360 h), solvent extracted and analyzed by gas chromatography—electron-capture detection. The effect of bubbling depth was checked to ensure that bubbles leaving the system were at equilibrium with HCHs in the aqueous phase. Henry's law constants determined at 35 and 45°C in SW were significantly higher (P≤ 0.05) than in DW for both α- and γ-HCH, but not at lower temperatures. The slopes (m) and intercepts (b) of log H vs. 1 / T plots were: α-HCH (DW, 0.5–45°C); m = −2810 ± 110, B = 9.31 ± 0.38; α-HCH (SW, 0.5–23°C); M = −2969 ± 218, B = 9.88 ± 0.76; γ-HCH (DW, 0.5–45°C); M = −2382 ± 160, B = 7.54 ± 0.54; γ-HCH (SW, 0.5–23°C); M = −2703 ± 276, B = 8.68 ± 0.96. Henry's law constants determined in this study compared well with those calculated from reported vapor pressure and solubility data.  相似文献   

Factors influencing the magnitude of phytoplankton primary production in a high-energy surf zone     

Eileen E. Campbell  G. C. Bate 《Estuarine, Coastal and Shelf Science》1987,24(6)

The main factors influencing phytoplankton primary production in the surf zone of the Sundays River Beach, Algoa Bay have been characterized. These factors include cell concentration, chlorophyll concentration, irradiance, temperature and salinity. Good relationships have been obtained between cell concentration, chlorophyll concentration and primary production. The P-I curves showed dependence on temperature with a linear regression between temperature and I_k values. Light saturation was shown to occur between 300 and 510 μmol m⁻² s⁻¹ at normal field temperatures. T_max and T_min were found to be 34°C and 0°C, respectively; P_max was 25°C. Salinity had a marked effect on primary production with S_max occurring at 60 ppt and an extrapolated S_min at 0 ppt. P_max was found to occur at 30 ppt.  相似文献   

Temperature dependence of CO₂ fugacity in seawater     

Catherine Goyet  Frank J. Millero  Alain Poisson  Deborah K. Shafer 《Marine Chemistry》1993,44(2-4)

Ideally, the correction of the measured CO₂ fugacity (fCO₂) at temperature T_m to fCO₂ at the in-situ temperature T_in should be made by using at least 2 known parameters (pH-A_T, C_T-A_T,…) and the reliable constants for carbonic acid. In practice however, a measured CO₂ property pair is not always available. When fCO₂ is measured alone, one must make an estimate of the effect of temperature on seawater fCO₂ from the accurate knowledge of seawater salinity and temperature and the approximate knowledge of the carbonate parameters. In this paper we present an empirical relationship that can be used to estimate the effect of temperature on fCO₂. The equation is of the form: where fCO_2[t] and fCO_2[20] represent fCO₂ at temperatures t°C and 20°C, respectively; the parameters A, B, etc. are functions of the ratio X = C_T/A_T: where the parameters a_i, b_i, etc. are functions of salinity.The 25-parameter equation is fitted by the values of fCO₂ calculated using the constants of Goyet and Poisson (1989), when X varies from 0.8 to 1.0, t varies from −1dgC to 40°C, and S varies from 30 to 40. For T_m - T_in within ± 10°C, direct measurements of fCO₂ as a function of the temperature (from −I to 30°C verify this equation within less than ±5 μatm.  相似文献   

Short-term variability of fCO₂ in seawater and air–sea CO₂ fluxes in a coastal upwelling system (Ría de Vigo, NW Spain)     

J. Gago  M. Gilcoto  F. F. Prez  A. F. Ríos 《Marine Chemistry》2003,80(4):247-264

Coastal upwelling systems are regions with highly variable physical processes and very high rates of primary production and very little is known about the effect of these factors on the short-term variations of CO₂ fugacity in seawater (fCO₂^w). This paper presents the effect of short-term variability (<1 week) of upwelling–downwelling events on CO₂ fugacity in seawater (fCO₂^w), oxygen, temperature and salinity fields in the Ría de Vigo (a coastal upwelling ecosystem). The magnitude of fCO₂^w values is physically and biologically modulated and ranges from 285 μatm in July to 615 μatm in October. There is a sharp gradient in fCO₂^w between the inner and the outer zone of the Ría during almost all the sampling dates, with a landward increase in fCO₂^w.CO₂ fluxes calculated from local wind speed and air–sea fCO₂ differences indicate that the inner zone is a sink for atmospheric CO₂ in December only (−0.30 mmol m⁻² day⁻¹). The middle zone absorbs CO₂ in December and July (−0.05 and −0.27 mmol·m⁻² day⁻¹, respectively). The oceanic zone only emits CO₂ in October (0.36 mmol·m⁻² day⁻¹) and absorbs at the highest rate in December (−1.53 mmol·m⁻² day⁻¹).  相似文献   

Carbon and nitrogen primary productivity in three North Carolina estuaries     

T. R. Fisher  P. R. Carlson  R. T. Barber 《Estuarine, Coastal and Shelf Science》1982,15(6)

Uptake of inorganic carbon and ammonium by the plankton community of three North Carolina estuaries was measured using ¹⁴C and ¹⁵N isotope methods. At 0% light, C appeared to be lost via respiration, and at increasing light levels uptake of inorganic carbon increased linearly, saturated (mean I_k = 358±30 μEin m⁻² s⁻¹), and frequently showed inhibition at the highest light intensities. At 0% light NH₄⁺ uptake was significantly greater than zero and was frequently equivalent to uptake in the light (light independent); at increasing light levels NH₄⁺ uptake saturated (mean I_k = 172±44 μEin m⁻² s⁻¹) and frequently indicated strong inhibition. Light-saturated uptake rates of inorganic carbon and NH₄⁺ were a function of chlorophyll a (r² = 0·7−0·9); average assimilation numbers were 625 nmol CO₂ (μg chl. a)⁻¹ h⁻¹ and 12·9 nmol NH₄⁺ (μg chl. a)⁻¹ h⁻¹ and were positively correlated with temperature (r² = 0·3−0·7). The ratio of dark to light-saturated NH₄⁺ uptake tended to be near 1·0 for large algal populations at low NH₄⁺ concentrations, indicating near light independence of uptake; whereas the ratio was lower for the opposite conditions. These data are interpreted as indicative of nitrogen stress, and it is suggested that uptake of NH₄⁺ deep in the euphotic zone and at night are mechanisms for balancing the C:N of cellular pools. A 24-h study using summed short-term incubations confirmed this; the cumulative C:N of CO₂ and NH₄⁺ uptake during the daylight period was 10–20, whereas over the 24-h period the ratio was 6 due to dark NH₄⁺ uptake. Annual carbon and nitrogen primary productivity were respectively estimated as 24 and 4·0 mol m⁻² year⁻¹ for the South River estuary, 42 and 7·3 mol m⁻² year⁻¹ for the Neuse River estuary, and 9·6 and 1·6 mol m⁻² year⁻¹ for the Newport River estuary.  相似文献