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1.
Zena G. Kaufman John S. Lively Edward J. Carpenter 《Estuarine, Coastal and Shelf Science》1983,17(5):483-493
The uptake of urea, nitrate and ammonium by phytoplankton was measured using 15N isotopes over a one-year period in Great South Bay, a shallow coastal lagoon. The bay is a unique environment for the study of nutrient uptake since ambient concentrations of and urea remain relatively high through the year, and phytoplankton are probably never nutrient limited. Urea nitrogen averaged 52% of the total assimilated, while ammonium represented 33% and nitrate 13%. High rates of ammonium uptake occurred only at low urea concentrations (ca< 1-μg-atom urea l?1). Over the sampling period urea was present in relatively high concentrations, averaging 5·35 μg-atom N l?1, while means for ammonium and nitrate averaged 1·94 and 0·65 μg-atom N l?1, respectively. Total N uptake measured with 15N averaged about 3·3 times the calculated (from elemental ratios and 14C productivity measurements) N needs of the phytoplankton population. Highest nitrogen uptake occurred in the summer and coincided with the primary production maximum. 相似文献
2.
The nitrogen relations of Enteromorpha spp. growing on intertidal mud flats have been examined over a twelve-month period. Nitrogen assimilation rates using 15N have been used to calculate the production of the alga and were between 0·046 and 0·217 mg (g dry wt alga)?1 h?1 A considerable quantity of the alga was buried beneath the sediment over the growth season and was calculated to be equivalent to an input of up to 9·52 g N m?2 per month and 32 g N m?2 over one complete growth season. Based on carbon, this latter value represented an input of approximately 320 g C m?2 annually. Low rates of nitrogenase activity (acetylene reduction) were found to be associated with the Enteromorpha. The organisms responsible for the nitrogenase activity were probably heterotrophic bacteria but they did not contribute significant quantities of nitrogen to the alga. 相似文献
3.
M.D Kumar 《Marine Chemistry》1983,14(2):121-131
A model is presented which signifies the role of oxygen (as oxides and hydroxides) in controlling the composition of seawater. Using the regression equations respective concentration and residence times for the unknown elements can be estimated. Geometric and statistical indices of Legget and Williams (1981) are used to evaluate the accuracy of the model. This reveals from the known values of ΔO2?M that the present model estimates log values within a factor of 1.77. The predicted oceanic residence times for Am, Ir, Ra and Rh are 3.6 × 102, 3.7 × 102, 2.2 × 105 and 6.4 × 102 years, respectively. 相似文献
4.
An investigation of ferric ion complexing has been conducted in synthetic media and seawater at 25°C. Formation constants were potentiometrically determined for the species FeCl2+, FeCl2+, FeOH2+, and Fe(OH)2+ at an ionic strength of 0.68 m. Formation constants for the ferric chloride complexes were determined as Clβ1 = 2.76 and Clβ2 = 0.44. In a study of the reaction Fe3+ + nH2O ? Fe(OH)n(3?n)+ + nH+ in NaClO4, NaNO3 and NaCl the formation constants were shown to be relatively independent of medium when the effects of nitrate and chloride complexing were taken into account. The average values obtained for these constants are . Reasonable agreement with these values was obtained when these constants were determined in seawater by accounting for the effects of chloride, fluoride and sulfate complexing. 相似文献
5.
Losses of 15N labelled nitrogen in a Spartina alterniflora salt marsh was measured over three growing seasons. Labelled equivalent to 100 μg 15N g?1 of dry soil was added in four instalments over an eight week period. Recovery of the added nitrogen ranged from 93% 5 months after addition of the to 52% at the end of the third growing season which represented a nitrogen loss equivalent to 3·4 gNm?2. The availability of the labelled incorporated into the organic fraction was estimated by calculation of the rate of mineralization. The time required for mineralization of 1% of the tagged organic N increases progressively with succeeding cuttings of the S. alterniflora and ranged from 152 to 299 days. Only 2% of the nitrogen applied as 15N labelled plant material to the marsh surface in the fall could be accounted for in S. alterniflora the following season. 相似文献
6.
Iron solubility equilibria were investigated in seawater at 36.22‰ salinity and 25°C using several filtration and dialysis techniques. In simple filtration experiments with 0.05 μm filters and Millipore ultra-filters, ferric chlorides fluorides, sulfates, and FeOH2+ species were found to be insignificant relative to Fe(OH)2+ at p[H+] = ?log [H+] greater than 6.0. Hydrous ferric oxide freshly precipitated from seawater yielded a solubility product of . Solubility studies based on the rates of dialysis of various seawater solutions and on the filtration of acidified seawater solutions indicated the existence of the Fe(OH)30 species. The formation constant for this species can be calculated as . The Fe(OH)4? species is present at concentrations which are negligible compared to Fe(OH)2+ and Fe(OH)30 in the normal pH range of seawater. However, there is at least one other significant ferric complex in seawater above p[H+] = 8.0 (possibly with bicarbonate, carbonate, or borate ions) in addition to the Fe(OH)2+ and Fe(OH)30 species. 相似文献
7.
Equilibrium constants for copper(II)-carbonate and -bicarbonate species have been determined at 25°C from consideration of malachite, Cu2(OH)2CO3(s), solubility in UV-photo-oxidized perchlorate solutions of 0.72 m ionic strength. The ratios of total dissolved copper, T(Cu), to free copper(II) ion, [Cu 2+], in 30 malachite saturated experimental solutions of 1–10 × 10?3eq kg?1 H2O initial total alkalinity (TAi in the pH range 5.0–9.3 were fitted to a copper(II)-ion speciation model. The experimental data indicate the existence of CuCO3+, CuHCO3+ and Cu(OH)CO3? in addition to the hydrolys and Cu(OH)CO3? in addition to the hydrolysis products in the range of conditions defined by this study. The stoichiometric equilibrium constants, applicable to seawater at 0.72 m ionic strength, 25°C and 1 atm are A speciation model employing the equilibrium constants determined in this study and copper(II) hydrolysis constants from previous work suggests that the inorganic speciation in seawater (pH = 8.2, TA = 2.3 meq kg ?1, 25°C) is dominated by the CuCO30 complex (82%) and that only 2.9% of the total inorganic copper exists as the free copper(II) ion. Hydrolysis products, CuOH+ and Cu(OH)20, account for 6.5% while CuHCO3+ and Cu(OH)CO3? species comprise 1.0 and 6.3% of the total inorganic copper, respectively. 相似文献
8.
Laboratory investigations were conducted on the formation of NaF° ion-pairs at the ionic strength of seawater using specific ion electrodes. Sodium and fluoride ion electrodes produced results which are consistent with the ion-pairing model for these ionic interactions. The stoichiometric association constant for NaF°, , was determined at 15, 25, and 35°C. It was assumed that was a function of temperature, pressure, and ionic strength but not of solution composition. The value for at 25°C and I = 0.7 m is 0.045 ± 0.006. increased with decreasing temperature. This result was used to recompute values of and accounting for the presence of NaF° ion-pairs. The value for indicates that 1.1% of the fluoride in seawater is ion-paired with sodium at 25°C and 35‰ salinity. This fraction increases to approximately 2% at the lower temperatures found in the deep ocean. The percentage of free fluoride in natural seawater was measured at 15, 25, and 35°C to verify the speciation calculated from equilibrium constants. 相似文献
9.
The density of artificial seawater has been measured with a magnetic float densitometer at 1 atm. from 0 to 40°C (in 5° intervals) and from 0 to 21‰ chlorinity. The densities at each temperature have been fitted to a modified Root (1933) equation, and an equation based on the Debye-Hückel limiting law, where AV′, BV′, AV, BV and CV are temperature-dependent constants (related to the ion-water and ion-ion interactions of the major components), d0 is the density of pure water and ClV is the volume chlorinity — . The densities fit these equations to ±9 p.p.m. from 0 to 25°C and ±18 p.p.m. from 30 to 40°C. The densities for artificial seawater are in good agreement with our measurements of Copenhagen seawater and the results for natural seawater obtained from Knudsen's tables.The expansibilities of the artificial seawater mixtures have been calculated from the temperature dependence of the densities. The resulting expansibilities at each temperature were fitted to the equations and where AE′, BE′, AE, BE and CE are constants (related to the effect of temperature on the ion-water and ion-ion interactions of the major components) and α0 is the expansibility of pure water. The expansibilities fit these equations to ±1 p.p.m. and at 35‰ S agree within ±1 p.p.m. with the expansibilities obtained for natural seawater from Knudsen's tables.Theoretical density and expansibility constants have been determined from the apparent equivalent volumes and expansibilities of the major components of seawater by using the additivity principle. The average deviations of the calculated densities and expansibilities are, respectively, ±20 and ±3 p.p.m. over the entire temperature range. 相似文献
10.
The apparent ionization constants for silicic acid, k1 and k2, and the ionic product of water, kw, have been determined in 0.05, 0.1, 0.2, 0.4 and 2.0 M Na(CI) media at 25°C. The medium dependence of these constants was found to fit equations of the form where K1 is the ionization constant in pure water, αi and bi are parameters of which bi has been adjusted to present data. The following results were obtained (αi, bi): pK1 = 9.84, (1.022, ?0.11); pK2 = 13.43, (2.044, ?0.20); and pKw = 14.01 (1.022, ?0.22). ki values are collected in Tables I and II. Attempts have been made to explain the medium dependence of k1 and k2 with weak sodium silicate complexing according to the equilibria giving k11 = 0.37M?1 and k21= 3.0M?1. However, these weak interactions cannot be interpreted unambiguously from potentiometric data at different 1-levels. Probably the medium dependence could equally well be expressed by variations in the activity coefficients.The measurements were performed as potentiometric titrations using a hydrogen electrode. The average number of OH- reacted per Si(OH)4, Z, has been varied within the limits 0 ? Z ? 1.1 and B1, the total concentration of Si(OH)4, between 0.001 M and 0.008 M. k1 was evaluated from experimental data with B ? 0.003 M, and k2 with B ? 0.008 M and Z ? 0.95. 相似文献
11.
Vertical measurements of , and N2O concentrations, and uptake, and oxidation rates were measured at 5 sites in western Cook Strait, New Zealand, between 31 March and 3 April 1983. Nitrate increased with depth at all stations reaching a maximum of 10.5 μg-atom at the most strongly stratified station whereas was relatively constant with depth at all stations (～0.1 μg-atom ). The highest rates of oxidation generally occurred in the near surface waters and decreased with depth. N2O levels were near saturation with respect to the air above the sea surface and showed no obvious changes during 24 h incubation. oxidation by nitrifying bacteria may account for about 30% of the total utilization (i.e. bacterial+agal) and, assuming oxidation through to , may supply about 40% of the algal requirements of in the study area. These results suggest that bacterial nitrification is of potential importance to the nitrogen dynamics of the western Cook Strait, particularly with respect to the nitrogen demands of the phytoplankton. 相似文献
12.
Peter Nielsen 《Coastal Engineering》1985,9(3):261-276
An empirical analysis is performed on the most detailed, recent measurements of turbulent oscillatory boundary layer flow. The measurements show that throughout elevations where the flow can be considered horizontally uniform, one deficit model is sufficient for describing the fundamental mode. Some general properties of the non dimensional velocity deficit D1(z) appear with striking consistency. First of all the identity , which is a theoretical result for smooth laminar flow, seems to hold with great accuracy for a large range of turbulent flow conditions as well. This is of principal theoretical interest because all previous analytical eddy viscosity models as well as numerical mixing length models predict a consistent and fairly large difference between Arg D1 and . If the identity between and Arg D1 extends all the way to the bed, it means that the bed shear stress leads the free stream velocity by 45 degrees. It is also found that the structure of smooth turbulent oscillatory flows as measured by Kalkanis (1964) corresponds to a sharp maximum in the normalized energy dissipation rate. 相似文献
13.
Spectrophotometric measurements are reported for the first apparent dissociation constant of hydrogen sulfide in seawater over the temperature range 7.5–25°C and 2–35.8‰ salinity. These data are described by the expression . The second apparent dissociation constant in potassium chloride solution was estimated potentiometrically using a sulfide specific ion electrode. A value of ～13.6 was found for pK2′ at a KCl concentration of 0.67 M. It is suggested that explicit reference to the sulfide ion, S2?, in describing equilibria in marine waters be dropped in favor of a formulation involving the bisulfide ion, HS?. 相似文献
14.
James G Wilson 《Marine environmental research》1983,8(3):129-148
The concentration of Ni in C. edule ranges from 17·8 μg/g to 53·82 μg/g with the highest concentration in the gills and mantle and the lowest in the foot and adductor muscles. The concentration does not change with either size or season.There is no significant increase in mortality even in the highest Ni concentration (100 μg/litre), nor is body condition correlated with experimental Ni concentrations. The rate of uptake of Ni (y) is described by the equation: where x1 = Ni concentration (μg/litre) and x2 = time (h).The respiration rates did not significantly change up to the highest Ni concentration used (1000 μg/litre).It is postulated that the main pathway for Ni uptake is through the gills, possibly through mucus sheet or transmembrane absorption, with a secondary uptake route via the viscera.C. edule may therefore be a suitable indicator species for Ni. 相似文献
15.
The addition of various concentrations (1, 10 and 20 mM) of Group VI anions to sediment slurry resulted in inhibition of the rate of sulphate reduction at the two higher concentrations, the degree of inhibition being in the order of molyb-date . The addition of 20 mM concentrations of these inhibitors almost entirely eliminated sulphate reduction. Doubling the sulphate concentration while using the highest concentration of inhibitors (20 mM) led to the re-establishment of some sulphate reduction in the and treated slurries whereas no such reversal was noticed with . These observations suggested that and are competitive inhibitors of sulphate reduction, while is a non-competitive inhibitor. 相似文献
16.
Four experiments were carried out to determine the effect of different temperatures, light levels and biological activities on the residence times of petroleum hydrocarbons. No. 2 fuel oil was added as a seawater dispersion to give an initial concentration of 150 to 300 μg/litre in the water columns of large, outdoor marine microcosms. Hydrocarbons in water samples fractionated on passage through glass fibre filters (0·3 μm pore size) according to the solubilities, so that 80–90 % of the aromatics entered the filtrate while all of the saturates were trapped by the filter. The removal of oil compounds from the water columns was exponential, with rates which appeared to be determined chiefly by the temperature. The half life of total hydrocarbons varied from more than 10 days in March to ～30 h in July and September. Volatilisation was hypothesised to be an important removal mechanism for the 40–60% of the saturates which were not sedimented with suspended particulate matter. In warm water, the residence times of normal alkanes were increased up to 50 % by poisoning the water column, but no similar increase was noted for the bulk of the F1 hydrocarbons. Aromatic (F2) hydrocarbons appeared to be removed slowly volatilisation from cold water () and rapidly by biodegradation from warm water (). 相似文献
17.
The apparent solubility product of aragonite in 32‰ seawater at 25.0°C is reported as K′sp = (0.869±0.049) × 10?6(mol2kgseawater?2) thus confirming the value of R.A. Berner, 1976 (Am. J. Sci., 276: 713–730). The apparent solubility product ratio for aragonite and calcite is reported as The deviation of this value from the thermodynamic ratio is atttributed to the formation of a stable low Mg-calcite coating on pure calcite in seawater measurements of solubility. 相似文献
18.
A field investigation was carried out to collect data of inner bar migration. Profiles were measured once or twice a week for a two-year period at Naka Beach, Ibaraki Prefecture, Japan. It was found that the onshore migration of inner bars could be described by two dimensionless quantities as: where (Hb)max is the maximum value of daily average breaker height during one interval between surveys, Tmax is the average wave period of the day giving (Hb)max, D is the mean size of the beach sediment, and g is the acceleration due to gravity. Analyses based on surfzone sediment dynamics yields , where is the average speed of onshore bar-migration, b is the bar height, is the average breaker height, and w is the fall velocity of the beach sediment. Nomographs for the speed of landward migrating bars are also presented. 相似文献
19.
The concentrations of Ni, Mn, Cr, Cu, Co, Zn, Fe, Pb and organic carbon have been determined in sediments of the Pagassitikos Gulf. They vary with the ‘sand equivalent’ content, s′, characteristic of the grain size, and are related to it by the equation, in which the constants c1, k and d depend on the element. Consequently, since the metal concentrations in a sample are much less representative of the area from which it has been taken than its ‘sand equivalent’ content, a contour map of the latter constitutes a reliable guide to the general pattern of the elements. Superimposed on it, we detect isolated patches of moderate pollution close to the harbour of Volos and a few, slight, natural anomalies, such as increased Mn and Ni, the former in the east and the latter in the south of the Gulf. 相似文献