A convenient method for the determination of carbon in marine “net zooplankton”

Measurements of carbon in marine “net zooplankton” were made by use of a Leco 70 Second TC-12 Automatic Carbon Determinator. The instrument employs high-temperature (ca. 1600°C), dry-combustion and thermal-conductivity detection of the purified carbon-dioxide combustion product and oxygen carrier gas mixtures. The methodology developed in this study is convenient and rapid (ca. 70 sec per freeze-dried sample), with a mean error ($\text{±2σ/}\text{x}\text{·100}$) of ±4.4% at the 3 mg-C level and ±7.4% at the 10 mg-C level when benzoic acid is used as a standard, and ±9.2% at the 5 mg-C level and ±6.0% at the 10 mg-C level when casein is used as the standard. The technique was applied to the “splash zone” marine copepod Tigriopus californicus to obtain an average value of 38.6% C by weight. Concentrated samples of “net zooplankton” of varying size fractions were collected in the Monterey upwelling region over an eight-month period. Values up to 2000 mg-C/m² ocean surface (0–200 m) were observed in a seasonal cycle doubly peaked for some size fractions but not for others.     

The solubility of calcite — probably containing magnesium — in seawater

The apparent solubility product of calcite was measured by saturometry as a function of temperature and salinity. Simplified equations for the carbonic-acid dissociation constants of Mehrbach et al., 1973 (Limnol. Oceanogr., 18: 897–907) have been derived from their experimental data and used to calculate apparent solubility product, K′_sp, K′_sp at 25°C and 35‰ salinity, was found to be K′_sp = 4.70 × 10^?7(mol²kgseawater^?2) An equation was fitted to the experimental data, resulting in pK′_sp = 6.5795 ? 3.7159 × 10⁵(TS) + 0.91056(T/S) ? 22.110(1.0/S)The mean activity coefficients, $\text{γ±}\text{CaCO}{}_3$, were calculated at various temperatures and salinities, using the thermodynamic solubility product of Jacobson and Langmuir, 1974 (Geochim. Cosmochim. Acta, 38: 301–318) and the apparent solubility products quoted in their paper. The change in K′_sp at each salinity, as a function of temperature, was used to calculate the apparent enthalpy of dissociation for calcite, ΔH′, and the extrapolated value of ΔH⁰ was in good agreement with that of Jacobson and Langmuir. Finally, this work was used to calculate saturation profiles for oceanic stations and as a basis for comment of the accuracy of in-situ saturometry, as well as the applicability of in-situ K′_sp pressure corrections.     

The solubility of aragonite in seawater at 25.0°C and 32.62‰ salinity

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 $\text{K′}{}_{\mathrm{aragonite}}\text{K′}{}_{\mathrm{calcite}}\text{= 2.05}$ 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.     

Chemical determination of particulate nitrogen in San Francisco Bay. Nitrogen: chlorophyll a ratios in plankton

Particulate nitrogen (PN) and chlorophyll a (Chla) were measured in the northern reach of San Francisco Bay throughout 1980. The PN values were calculated as the differences between unfiltered and filtered (0·4 μm) samples analyzed using the UV-catalyzed peroxide digestion method. The Chla values were measured spectrophotometrically, with corrections made for phaeopigments. The plot of all $\text{PN}\text{Chl}\text{a}$ data was found to be non-linear, and the concentration of suspended particulate matter (SPM) was found to be the best selector for linear subsets of the data. The best-fit slopes of $\text{PN}\text{Chl}\text{a}$ plots, as determined by linear regression (model II), were interpreted to be the N: Chla ratios of phytoplankton. The Y-intercepts of the regression lines were considered to represent easily-oxidizable detrital nitrogen (EDN). In clear water ( < 10 mg l^?1 SPM), the N: Chla ratio was 1·07 μg-at N per μg Chla. It decreased to 0·60 in the 10–18 mg l^?1 range and averaged 0·31 in the remaining four ranges (18–35, 35–65, 65–155, and 155–470 mg l^?1). The EDN values were less than 1 μg-at N l^?1 in the clear water and increased monotonically to almost 12 μg-at N l^?1 in the highest SPM range. The N: Chla ratios for the four highest SPM ranges agree well with data for phytoplankton in light-limited cultures. In these ranges, phytoplankton-N averaged only 20% of the PN, while EDN averaged 39% and refractory-N 41%.     

δ13C analyses of oceanic particulate organic matter

Seventy-nine δ¹³C analyses of oceanic particulate matter (> 0·μ) from semi-tropical (Gulf of Mexico, Caribbean and Atlantic) and polar (South Indian Ocean) waters showed that the carbon isotope composition of the particulate matter from the cold polar surface waters was lighter ($\text{?24·7}\text{to}\text{?26·0‰}$) than that from the surface in the semi-tropical regions ($\text{?19·8}\text{to}\text{?22·3 ‰}$), reflecting the temperature effect on the photosynthetic fixation of carbon. δ¹³C for deep samples (> 330 m) were generally more negative than the surface samples, except in some well-mixed polar areas.A difference both in organic carbon isotopic composition and percentage organic carbon in the POM and the tops of sediment cores was also apparent; a loss of approximately 95 % of incoming carbon and an increase in ¹³C of several per mille being observed during deposition of particulate matter. This indicates that after settling on the bottom there is extensive diagenesis of the POM by organisms, indicating the non-refractory nature of the organic matter.     

Sodium fluoride ion-pairs in seawater

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°, $\text{K}{}^1{}_{\mathrm{<mtext>NaF</mtext>}}$, was determined at 15, 25, and 35°C. It was assumed that $\text{K}{}^1{}_{\mathrm{<mtext>NaF</mtext>}}$ was a function of temperature, pressure, and ionic strength but not of solution composition. The value for $\text{K}{}^1{}_{\mathrm{<mtext>NaF</mtext>}}$ at 25°C and I = 0.7 m is 0.045 ± 0.006. $\text{K}{}^1{}_{\mathrm{<mtext>NaF</mtext>}}$ increased with decreasing temperature. This result was used to recompute values of $\text{K}{}^1{}_{\mathrm{<mtext>MgF</mtext>}}$ and $\text{K}{}^1{}_{\mathrm{<mtext>CaF</mtext>}}$ accounting for the presence of NaF° ion-pairs. The value for $\text{K}{}^1{}_{\mathrm{<mtext>NaF</mtext>}}$ 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.     

‘Reactive’ and ‘unreactive’ iodine in seawater — A possible indication of an organically bound iodine fraction

An iodine component in seawater, which is ‘unreactive’ to the total inorganic method described by Truesdale and Spencer (1974), has been discovered. The component is measured as the increase in ‘reactive’ iodine that accompanies irradiation of seawater with high-intensity UV light. The highest concentration recorded for an inshore water was $\text{5.2 ± 0.5}\text{μg/l}$. As some known organic-iodine compounds behave in a similar manner to UV irradiation, it is suggested that the ‘unreactive’ iodine is organically bound iodine.     

Deuterium content of humic acids from marine and non-marine environments

Deuterium values obtained for humic acids isolated from marine sediments from the NE Pacific are in the range of $\text{δ}\text{D}\text{= (?105 ± 5)‰}$, corresponding to values obtained for marine plankton from the same area. Soil humic acids have a much broader range of δD values (?57 to ?97‰), depending on the isotopic values of the precipitation and the isotopic composition of the parent plant precursor.Data obtained on hydrogen isotope distribution confirms previous hypotheses based on chemical analysis and on carbon isotopes, which indicated the authigenic nature of marine humates.     

The spatial and temporal development of the spring phytoplankton bloom in the Celtic Sea,April 1979

The results are presented from three hydrogrpahic surveys in April 1979 of a 40 × 50 km region of the Celtic Sea, centred at 7°W and 51°N, using a towed undulating sensor system. In the $\text{5}\text{1}\text{2}$ days between Surveys 1 and 2, the seasonal thermocline was established, with surface to bottom temperature differences reaching 1.5°C, the average surface chlorophyll a level increased from ～ 1 to ～ 5.5 mg m^?3 due mainly to the growth of diatoms, and the surface nitrate concentration decreased from 6 to 1 μM. The third survey was carried out after a further two days and, although surface properties changed little, there was a general deepening of the mixed layer due to stronger winds, and a further increase in the standing stock of phytoplankton.By applying appropriate techniques of horizontal spatial averaging, which took into account possible advective effects, a quantitative comparison was made of the changes at two positions in the survey area which showed significant differences in the rate of development of the phytoplankton population. A simple model of phytoplankton growth was then developed, based on calculations of eddy diffusivity, on measurements of rates of photosynthetic carbon assimilation, and on observations of carbon to chlorophyll ratios, subsurface light attenuation and inorganic nutrient levels. In the absence of any data on zooplankton populations, the loss of phytoplankton by grazing was left as a free parameter.The model was only partly successful in reproducing the observed changes in chlorophyll concentrations during the first $\text{5}\text{1}\text{2}$ days and showed serious limitations for the subsequent 2 days. However, it emphasised several features of the dynamics of spring phytoplankton populations which require further experimental or observational investigation. These include more precise measurements of carbon to chlorophyll ratios and grazing pressure to which the model is sensitive over a rather narrow range (this has important implications in terms both of control by grazing and nutrient limitation), the potential significance of physiological photoadaptation by the plant cells in determining their vertical distribution, and the role of eddy diffusion across the developing thermocline in relation to the sinking of phytoplankton cells and the upward mixing of inorganic nutrients.     

Parameters relating to the distributions of planktonic organisms,especially euphausiids in the eastern tropical Pacific

Zooplankton was sampled through eight depth intervals above about 500 m along a transect of the eastern tropical Pacific (ETP), 23°N to 3°S, encompassing four environments. (1) The California Current—ETP transition off Baja California and the mouth of the Gulf of California is inhabited by California Current species at their southern limits, and by the galatheid ‘red crab’ Pleuroncodes planipes together with euphausiids (e.g. Euphausia eximia) of an abundance-based recurrent group of species, distinguished using the criterion of $\text{>}\text{x}$ abundance (Numbers under unit area of sea surface) at common localities, adapted to productive zones marginal to the O₂-deficient part of the ETP. Tropical species appear here where water with surface temperature > 26°C and [O₂] of < 0.1 ml l^?1 beneath a shoaling thermocline replaces the upwelling environment off Baja California. (1) The zone 22° to 10°N harbors euphausiids of two groups: the vertically migrating tropical species (e.g. Euphausia diomedeae) which tolerate intense O₂-deficiency at their daytime depths and enter the oxygenated mixed layer at night, and non-migrating Stylocheiron species which have vertical ranges extending up into the mixed layer. Nevertheless, most of these ‘ETP-adapted’ species are denser farther south, in the north equatorial countercurrent, but three ETP endemics (e.g. E. distinguenda), all vertical migrators belonging in one subgeneric division of Euphausia, are densest in the O₂-deficient regions. (3) The zone of the North Equatorial Countercurrent maintains high densities of three groups: the widely-ranging, ETP-adapted tropical species, the four common Stylocheiron species which, while recurring in abundance at the same localities, differ in depth and the mesopelagic tropical-subtropical species, not tolerant of O₂-deficiency, which occur here in easterly tongues of range. (4) At the equator (93°W), easterly ranging species (e.g. E. paragibba) and westerly Nyctiphanes simplex appear to migrate between equatorial currents which differ in direction with depth, thereby maintaining their narrow ranges along the equator. The ‘marginal proliferators’ such as E. eximia, prominent off Baja California, are again abundant here, availing of the equatorial divergence for high productivity and of the oppositely-directed currents for geographical stability.A second recurrent grouping of species, based on presence of their larvae at common localities, yielded groups also distinguishable by whether the larvae lived within or beneath the mixed layer.Ontogenetic strengthening of vertical migration capability is demonstrated by many species, with older larvae, juveniles and adults showing ranges, respectively, increasing from a few meters to up to 400 m. The pattern is the same in O₂-deficient regions as elsewhere.Regional distribution of euphausiid volume (wet displacement biomass) tended to agree with zooplankton volume, with maxima at the equator, 8°N, and at some localities off Baja California and the Gulf of California where red crab volume peaked. The depth at which euphausiid volume is equal in amount day and night, across which vertical migration takes place, is designated the equilibrium depth (EqD) for euphausiid volume. EqD for euphausiids generally agreed with EqD for zooplankton volume, indicating that euphausiids play a role in determining depth of EqD for zooplankton volume. Euphausiids comprised 13% ($\text{x}$) of zooplankton volume. 80% ($\text{x}$) of euphausiid volume migrated across EqD, the value showing no significant regional differences. 37% ($\text{x}$) of zooplankton volume engaged in such migration, but in the region south of 14°N encompassing the broad O₂-deficient zone, the value was 26%, which compares with 18% previously determined for biomass transferring in a comparable way between epiplankton and planktostad in the same region.     

Transport variability in the Lanzarote passage (eastern boundary current of the North Atlantic subtropical Gyre)

Observations from a four-year current meter mooring at 28°44′N, 13°28′W in the Lanzarote passage are used to describe the transport variability of the Eastern Boundary Current of the North Atlantic Subtropical Gyre. Three different water masses are found in the passage: North Atlantic Central Water in the upper levels (roughly $\text{0}\text{–}\text{600}\text{m}$), Antarctic Intermediate Water (roughly $\text{600}\text{–}\text{1100}\text{m}$) and Mediterranean Water in the layer above the bottom at $\text{1300}\text{m}$. The mean southward transport of NACW is $\text{−0.8±1.1}\text{Sv}$ $\text{(1}\text{Sv}\text{=10}{}^9\text{kg}\text{s}{}^{\mathrm{-1}}\text{)}$ which is the transport of the easternmost branch of the Canary Current. Fluctuations of NACW transport are large, ranging from $\text{−3.4}\text{Sv}$ southward to $\text{1.7}\text{Sv}$ northward. Every autumn a consistent northward transport is observed, which may be related with the eastern boundary upwelling dynamics. The mean transports of AAIW and MW are $\text{0.1±0.4}\text{Sv}$ northward and $\text{−0.05±0.09}\text{Sv}$ southward, respectively. Fluctuations of transport of AAIW and MW are large, from 1.0 to $\text{−1.0}\text{Sv}$ and from −0.32 to $\text{0.23}\text{Sv}$, respectively. Thus, the mass transports for each water mass show a high standard deviation of comparable magnitude to the mean. This highlights the importance of the temporal variability of the currents in this passage. A remarkable feature of our observations is that the mean transports of NACW and AAIW during an El Niño event are significantly different.     

The density and expansibility of artificial seawater solutions from 0 to 40°C and 0 to 21‰ chlorinity

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, $\text{d = d}{}^0\text{+}\text{A}{}_{\mathrm{V}}\text{′ Cl}{}_{\mathrm{V}}\text{+ B}{}_{\mathrm{V}}\text{′ Cl}{}_{\mathrm{V}}{}^{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}$ and an equation based on the Debye-Hückel limiting law, $\text{d = d}{}^0\text{+}\text{A}{}_{\mathrm{V}}\text{Cl}{}_{\mathrm{V}}\text{+ B}{}_{\mathrm{V}}\text{Cl}{}_{\mathrm{V}}{}^{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}\text{+ C}{}_{\mathrm{V}}\text{Cl}{}_{\mathrm{V}}{}^2$ where A_V′, B_V′, A_V, B_V and C_V 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 Cl_V is the volume chlorinity — $\text{Cl}{}_{\mathrm{V}}\text{= Cl (‰) × density}$. 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 $\text{α = α}{}^0\text{+}\text{A}{}_{\mathrm{E}}\text{′ Cl}{}_{\mathrm{V}}\text{+ B}{}_{\mathrm{E}}\text{′ Cl}{}_{\mathrm{V}}{}^{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}$ and $\text{α = α}{}^0\text{+}\text{A}{}_{\mathrm{E}}\text{Cl}{}_{\mathrm{V}}\text{+ B}{}_{\mathrm{E}}\text{Cl}{}_{\mathrm{V}}{}^{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}\text{+ C}{}_{\mathrm{E}}\text{Cl}{}_{\mathrm{V}}{}^2$ where A_E′, B_E′, A_E, B_E and C_E 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.     

On the structure of oscillatory boundary layers

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 $\text{ln}\text{¦D}{}_{\mathrm{<mtext>1</mtext>}}\text{¦ ≡}\text{Arg}\text{D}{}_{\mathrm{<mtext>1</mtext>}}$, 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 $\text{ln}\text{¦D}{}_{\mathrm{<mtext>1</mtext>}}\text{¦}$. If the identity between $\text{ln}\text{¦D}{}_{\mathrm{<mtext>1</mtext>}}\text{¦}$ 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.     

The refractive index of seawater — comparison of experimental values and estimates from binary solution data

The Tait-Gibson parameter, $\text{B}{}^1$, and the refractive index of seawater are estimated from binary solution data. The predicted and experimental values agree closely. The maximum deviations, at $\text{S = 40‰}$, are 1.7 bars for $\text{B}{}^1$ and 0.0001 for the refractive index. The results show that binary solution data, analysed on the basis of the Tammann-Tait-Gibson model for aqueous solutions, can be used to predict the properties of seawater of composition different to that of standard seawater.     

Peculiarities of the primary production process in the Kara Sea at the end of the vegetation season

Research was implemented from September 15 through October 4, 2011 in the Kara Sea along transects located southeastwards Novaya Zemlya, in the St. Anna Trough, the Yenisei River estuary, and the adjacent shelf. The concentration of chlorophyll a was the highest in the photic zone (0.05–2.30 mg/m³, on average, 0.80 ± 0.37 mg/m³). The maximal concentration of Chl a at most of the stations located in the water layer of 7–30 m. Integral primary production in the water column varied from 3.0 to 151.0 mg C/m² per day, on average, 37.2 ± 36.6 mg C/m² per day. The maximal rate of primary production at most of the stations has been observed for the surface layer of the water column. Within the upper mixed water layer, relative primary production was from 31 to 100% (on average, 77 ± 20%). The most productive zone was the waters along Yenisei transect. In the estuary and at the adjacent shelf, primary production was 50 mg C/m² per day, exceeding the range observed for other areas by 1.5–2.0 times. The concentrations of silica and nitrogen together with light regime and water temperature were the major limiting factors affecting the primary production rate in the Kara Sea in autumn.     

An analysis of 3.5 kHz acoustic reflections and sediment physical properties

Near-bottom normal incidence acoustic reflection data and sediment physical property data are used to study the relationships between acoustic reflections and sediment physical properties. A pinger-hydrophone experiment was performed to obtain the necessary acoustic reflection data. In addition, a standard piston core was retrieved in the acoustic survey area for physical property analysis. The piston core was sampled and 13 properties were measured at 55 locations within the top 12 m of the core. Correlation studies amongst the sediment physical properties resulted in the following strong correlations: acoustic impedance ($\text{Z}$) and porosity ($\text{N}$), (0.96); water content ($\text{WC}$) and $\text{Z}$, (0.95); bulk density ($\text{BD}$) and $\text{Z}$, (0.99).The empirical orthonormal function (EOF) method was employed for acoustic signal analysis. This method assumes no a-priori models of the sediment or causality. The EOF method reduced the acoustic data to 8 functions that contained 97.6% of the sample variance. The EOFs were subsequently analysed by using cepstrum analysis which reveals time delay information and enhances detecting zones of reflectivity. The result of the sediment physical property and cepstrum analysis indicates that zones of reflectivity are essentially zones of relatively high acoustic impedance, low porosity, and low phi (high mean grain size).     

Apparent dissociation constants of hydrogen sulfide in chloride solutions

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 $\text{p}\text{K}{}_1\text{′ = 2.527 ? 0.169 Cl}{}^{\mathrm{<mtext>1</mtext><mtext>3</mtext>}}\text{+ 1359.96/T}$. 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, S^2?, in describing equilibria in marine waters be dropped in favor of a formulation involving the bisulfide ion, HS^?.     

MgSO4 ION association in seawater

Examination of the consequences of the stoichiometric association constant $\text{K}{}^1{}_{\mathrm{<mtext>a</mtext>}}\text{= 41.7}$ for MgSO₄ in seawater as advocated by Johnson and Pytkowicz (1979) leads to a thermodynamic association constant K_a = 212.6, a value 32% greater than K_A = 160 derived from conductance data. Use of K_a = 160 leads to a $\text{K}{}^1{}_{\mathrm{<mtext>a</mtext>}}$ in essential agreement with the value of 10.2 reported by Kester and Pytkowicz (1969).