Particulate organic matter in the coastal and estuarine waters of Goa and its relationship with phytoplankton production     

X.N. Verlencar  S.Z. Qasim 《Estuarine, Coastal and Shelf Science》1985,21(2):235-243

In the coastal and estuarine waters of Goa, particulate organic carbon (POC) varied from 0.52 to 2.51 mg l^?1 and from 0.28 to 5.24 mg l^?1 and particulate phosphorus (PP) varied from 0.71 to 5.18 μg l^?1 and from 0.78 to 20.34 μg l^?1, respectively. The mean values of chlorophyll and primary productivity were 1.94 mg m^?3 and 938.1 mg C m^?2 day^?1 in the coastal waters and 4.3 mg m^?3 and 636.5 mg C m^?1 day^?1 in the estuarine waters, respectively.$\text{POC}\text{chl}$ ratios were low in June and October even when POC values were quite high. The POC in surface waters was linearly correlated with the chlorophyll content. Also PP increased when chlorophyll and primary productivity remained high. The results suggest that the phytoplankton was sharply increasing and contributed to POC and PP content. The percentage of detritus calculated from the intercept values of chlorophyll on POC varied from 46 to 76% depending on season. Results indicate that the major portion of POC and PP during postmonsoon (October–January) is derived from phytoplankton production while the allochthonous matter predominate during monsoon (June–September).  相似文献   

The inorganic carbon system in the coastal upwelling region west of Vancouver Island,Canada     

《Deep Sea Research Part I: Oceanographic Research Papers》2003,50(8):1023-1042

We present inorganic carbon data from the coastal upwelling region west of Vancouver Island, Canada $\text{(∼48.5°}\text{N}\text{,}\text{126°}\text{W}\text{)}$ directly after an upwelling event and during summer downwelling in July 1998. The inner-shelf buoyancy current, the outer-shelf and the slope regions are contrasted for both wind regimes (up- and downwelling). Results show strong biological drawdown of the partial pressure of carbon dioxide (pCO₂) in response to upwelling over the outer-shelf. In contrast, measured pCO₂ is exceptionally high $\text{(p}\text{CO}{}_2\text{>1000}\text{ppm}\text{)}$ in the inner-shelf current, where biological uptake of carbon is consistently large. The biological C:N uptake ratio appears to increase when nitrogen becomes limiting (during downwelling), while the POC:PON ratio is relatively constant (slightly lower than the Redfield ratio) suggesting that excess carbon uptake does not go into the POC pool. As expected, large cells dominate where measured primary productivity is greatest. Sub-surface inorganic carbon (and pCO₂) is high over the shelf. We suggest that carbon concentrations may be higher in coastal waters because of remineralization associated with high productivity that is confined to a smaller volume of water by bathymetry. At the coast these sub-surface concentrations are more efficiently mixed into the surface (especially during winter) relative to deeper offshore regions. Thus, despite high primary production, coastal waters may not aid in sequestration of atmospheric carbon.  相似文献   

δ13C analyses of oceanic particulate organic matter     

Brian J. Eadie  Lela M. Jeffrey 《Marine Chemistry》1973,1(3):199-209

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.  相似文献   

Seasonal variability in microplanktonic biomasses in the Gironde dilution plume (Bay of Biscay): relative importance of bacteria     

《Oceanologica Acta》1998,21(4):563-580

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

S.W. Hager  D.D. Harmon  A.E. Alpine 《Estuarine, Coastal and Shelf Science》1984,19(2):193-204

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%.  相似文献   

Factors affecting the biokinetics of technetium (^95mTc) in marine macroalgae     

S. Topcuoǧlu  S.W. Fowler 《Marine environmental research》1984,12(1):25-43

Technetium (Tc) biokinetics were investigated in marine macroalgae using ^92mTc as tracer. Green and red algae accumulated Tc (VII) to a very low degree (CF ? 1–20); however, a much higher affinity for pertechnetate was found in some brown algal species (CF > 10³). Comparative tests with different species of brown algae revealed that technetium does not accumulate similarly in all species of this group. Moreover, no significant differences in radionuclide uptake were noted between brown algae exposed to Tc in either the IV or VII oxidation states. Bioaccumulation of technetium appears to be a metabolically controlled process since uptake did not occur in heat-killed individuals and both light and temperature significantly enhanced the accumulation of technetium in brown algae. Dissection of Sargassum vulgare following the uptake phase showed that the rapidly growing air bladder, leaf-like laterals and small branches contained higher Tc concentrations and retained a greater fraction of the radioactivity than the older, cylindrical main axis. Pertechnetate retention in two brown algae was found to be significantly different; their biological half-lives for Tc differed by an order of magnitude ($\text{T}{}_{\mathrm{<mtext>b</mtext><mtext>1</mtext><mtext>2</mtext>}}\text{= 19 and 196}\text{days}$). During depuration, loss took place more rapidly from the younger portions of the seaweed, as evidenced by the highest concentration and greatest fraction of Tc retained in the older, cylindrical main axis. Provided certain precautions are taken, brown algae such as Cystoseira compressa and S. vulgare would serve as good bioindicator organisms for the presence of Tc contamination in marine waters.  相似文献   

A deep sea,photographic nephelometer     

E.M. Thorndike 《Ocean Engineering》1975,3(1):1-15

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Nitrogen uptake,ammonium oxidation and nitrous oxide (N₂O) levels in the coastal waters of western Cook Strait,New Zealand     

John C. Priscu  Malcolm T. Downes 《Estuarine, Coastal and Shelf Science》1985,20(5):529-542

Vertical measurements of $\text{NH}{}_4{}^{\mathrm{+}}$, $\text{NO}{}_3{}^{\mathrm{?}}$ and N₂O concentrations, $\text{NO}{}_3{}^{\mathrm{?}}$ and $\text{NH}{}_4{}^{\mathrm{+}}$ uptake, and $\text{NH}{}_4{}^{\mathrm{+}}$ 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 $\text{NO}{}_3{}^{\mathrm{?}}\text{N l}{}^{\mathrm{?1}}$ at the most strongly stratified station whereas $\text{NH}{}_4{}^{\mathrm{+}}$ was relatively constant with depth at all stations (～0.1 μg-atom $\text{NH}{}_4{}^{\mathrm{+}}\text{N l}{}^{\mathrm{?1}}$). The highest rates of $\text{NH}{}_4{}^{\mathrm{+}}$ 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. $\text{NH}{}_4{}^{\mathrm{+}}$ oxidation by nitrifying bacteria may account for about 30% of the total $\text{NH}{}_4{}^{\mathrm{+}}$ utilization (i.e. bacterial+agal) and, assuming oxidation through to $\text{NO}{}_3{}^{\mathrm{?}}$, may supply about 40% of the algal requirements of $\text{NO}{}_3{}^{\mathrm{?}}$ 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   

Regional variations in Mn,Ni, Cu,and Co of ferromanganese nodules from a basin in the Southeast Pacific     

P. Halbach  V. Marchig  C. Scherhag 《Marine Geology》1980,38(4):M1-M9

Deep-sea nodules from the Southeast Pacific (northern sector of the Nazca Plate) have been studied regarding their metal content, shapes, and sedimentary environment. The area investigated lies in the southern boundary region of the equatorial zone of high biological productivity. The nodules accumulate by two different growth processes: (1) early diagenetic growth by supply from pore water and (2) hydrogenetic growth by supply from near-bottom sea-water. These growth processes lead to different genetic types of nodules. Considering the $\text{Mn}\text{Fe}$ ratio, the examined basin can clearly be divided in three ferromanganese facies. The $\text{Mn}\text{Fe}$ quotient increases generally from south to north, whereas Ni and Cu concentrations show a distinct maximum in the mid facies at a $\text{Mn}\text{Fe}$ ratio of about 5. Computing the correlation of $\text{Mn}\text{Fe}$ quotient versus (Ni+Cu), hyperbolic regressions show the best coefficients of correlation and separate the quantity of nodules in two groups. The ascending and the descending hyperbola represent two geochemical ranges which are controlled by different accumulation mechanisms.  相似文献   

Double-diffusive convection with a nonlinear equation of state: Part II. Laboratory experiments and their interpretation     

Trevor J. McDougall 《Progress in Oceanography》1981,10(2):91-121

The term cabbeling describes the convection that can occur when a mixture of two oceanic water masses is more dense than both of the parent water masses. When the two water masses are situated one above the other, the temperature and salinity distributions are in the correct senses for double-diffusive convection to occur and it is found that the prime effects of the nonlinearity of the equation of state are firstly to drive a greater level of double-diffusive convective activity in the lower layer than in the upper layer, and secondly, to make the lower edge of the interfacial region less gravitationally stable. Both of these effects cause the interface to migrate upwards as the lower layer grows at the expense of the upper layer. We introduce a nondimensional parameter $\text{δ}$ (called the cabbeling parameter) which represents the importance of the nonlinearity of the equation of state:—$\text{δ}$ is zero when the equation of state is linear and when cabbeling is normally thought to be possible, $\text{δ}$ is greater than unity. Experiments set up in both the finger and diffuse sense show how the nondimensional measure of the upward interface migration (called the “entrainment” parameter $\text{E}$) varies with the density anomaly ration R_? for various values of $\text{δ}$ between zero and 2.0 and that no abrupt change in this behaviour occurs at $\text{δ}\text{= 1.0}$. It is impossible to explain these observation by neglecting double-diffusive convection and considering only the convection driven by the conventional cabbeling instability. The successful interpretation of the laboratory results relies on considering the effects of a non-linear equation of state on the double-diffusive convection process.  相似文献   

The density of Red Sea brines     

Frank J. Millero  Alfonso Mucci  James Zullig  Peter Chetirkin 《Marine Chemistry》1982,11(5):463-475

The densities of artificial and real Red Sea brines have been measured at 25°C with a vibrating tube densimeter. Measurements were also made on mixtures of Red Sea brines with seawater and pure water. The results have been used to characterize the density—composition relations of waters across the interface of brine and average Red Sea waters. The results for the real and artificial brines are in reasonable agreement.The composition of the brines and mixtures with seawater have been characterized by conductivity measurements of weight diluted samples. The conductivity salinities were found to be conservative to within $\text{±0.07‰}$ for the mixtures.The densities of brines and mixtures of brines and seawater were estimated from apparent molal volume data using Young's rule. The calculated densities for all of the solutions were found to be in good agreement with the measured values, demonstrating the applicability of Young's rule to concentrated natural waters.  相似文献   

The use of factor analysis in determining beach erosion and accretion from grain-size data     

R. Dal Cin 《Marine Geology》1976,20(2):95-116

Factor analysis of grain-size percentages was conducted on 179 samples collected along beaches with erosion or accretion tendency. Four factors account for 95.7% of the initial information. These primarily represent the following populations: fine and very fine sands, medium-fine sands, medium-coarse sands and the fractions lying between 2.25 and 2.50 ?. By making various comparisons among the four factors, diagrams which adequately distinguished receding from advancing beaches were obtained. The results indicate that advancing beaches are particularly rich in fine and medium-fine sands; receding beaches are richer in medium-coarse and medium sands.The factorial analysis was also made on nine grain-size parameters obtained from the same beaches. Four factors account for 96.9% of the total information. The diagrams obtained from these factors also permit the identification of the two types of beaches. Advancing beaches generally show high mean (?), 99th percentile (?) and pelite percentage values. Receding beaches usually present an elevated kurtosis, higher negative (or lower, if positive) values of skewness and mean cubed deviation and a higher $\text{1}\text{st}\text{5}\text{th}$ percentile ratio (mm).It is hypothesized that the principal causes of the variations of the factors obtained are the differing energy level and the varying sediment supply on the two types of beaches; in addition, the initial grain size of the available material must be considered.  相似文献   

Some geochemical controls on lead and barium concentrations in ferromanganese deposits     

Cornelis H. Van Der Weijden  E.C. Kruissink 《Marine Chemistry》1977,5(2):93-112

The Pb content of natural deep-sea ferromanganese deposits decreases with depth. This is commonly explained by assuming oxidation of Pb²⁺ and uptake as (Mn, Pb)O₂ in normally oxygenated shallow water, a process that is less likely to occur in deep water which is somewhat depleted in oxygen. This concept is discussed and rejected, both on theoretical grounds and based on experimental results of Pb²⁺ sorption by Mn oxides. Comparative sorption experiments on Mn oxides were carried out with Pb and Ba. It is shown that Pb is preferentially adsorbed by birnessite at $\text{pH}\text{? 4}$. The uptake ratio is, however, much lower than the relative enrichment factor in natural nodule material. Suggested explanations for this discrepancy are: influence of hydrostatic pressure and extent of hydrolysis of the cations at the pH of ocean water.  相似文献   

Nitrogen and phosphorus concentrations within North Inlet,South Carolina—Speculation as to sources and sinks     

Thomas G. Wolaver  William Johnson  Marvin Marozas 《Estuarine, Coastal and Shelf Science》1984,19(2):243-255

The daily concentrations of $\text{NH}{}_4{}^{\mathrm{+}}$, $\text{NO}{}_3{}^{\mathrm{?}}$, and $\text{NO}{}_3{}^{\mathrm{?}}\text{+ NO}{}_2{}^{\mathrm{?}}$ within the North Inlet system are all negatively associated with tidal stage during the late summer, this association breaking down during the winter. The high concentrations of these constituents during low tide coupled with the lack of streamflow during the late summer suggests that there is an internal source for these species. Ammonium and orthophosphate most likely have their source in sediment diffusion from tidal creek sediments and/or seepage from the vegetated marsh surface during tidal exposure. It is hypothesized that high nitrate plus nitrite values at low tide are caused by nitrification within the tidal water or tidal creek sediments. During the summer there is evidence for a source of dissolved organic nitrogen and dissolved organic phosphorus within the North Inlet system, probably via diffusion from creek sediments. In general the main source of dissolved organic nitrogen is via stream-flow from the adjacent watershed. Particulate nitrogen and phosphorus concentrations are a function of: (1) wind and rain events which cause resuspension of particulate material from the tidal creek banks, (2) rain events which scour the marsh surface during tidal exposure, and (3) high tidal velocities which scour the creek bottoms.  相似文献   

Composition of Pacific Ocean ferromanganese nodules     

David Z. Piper  Michael E. Williamson 《Marine Geology》1977,23(4):285-303

Bulk composition of ferromanganese nodules from the pelagic environment of the Pacific Ocean is apparently related to nodule-growth rate, sediment-accumulation rate, and biologic productivity in the overlying seawater. Nodules with a high $\text{Mn}\text{Fe}$ ratio and high Ni and Cu concentrations tend to occur in areas where primary productivity in the surface layer of the ocean is high and the sediment-accumulation rate low. Nodules with a low $\text{Mn}\text{Fe}$ ratio and low Ni and Cu concentrations occur in areas either where sediment-accumulation rate is high or biologic productivity is low. They may have a $\text{Mn}\text{Fe}$ ratio as low as one and accrete at rates as low as $\text{1}\text{mm}\text{10}{}^6\text{yrs}$. Nodules with a larger $\text{Mn}\text{Fe}$ ratio apparently have growth rates that are greater by as much as a factor of 10.  相似文献   

Bacterial community composition during two consecutive NE Monsoon periods in the Arabian Sea studied by denaturing gradient gel electrophoresis (DGGE) of rRNA genes     

《Deep Sea Research Part II: Topical Studies in Oceanography》1999,46(8-9):1791-1811

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Stable isotope composition of dissolved sulfate and hydrogen sulfide in the Black Sea     

R.E. Sweeney  I.R. Kaplan 《Marine Chemistry》1980,9(2):145-152

The stable isotope ratio of sulfur (³⁴S/³²S) in dissolved sulfate and hydrogen sulfide was measured for 20 water samples from two deep hydrocasts from the south-central Black Sea. The isotope ratio of total reduced sulfur was also measured for surface sediment collected below each hydrocast. The range in the δ³⁴S measurements for sulfate was +18.20 to $\text{+20.17‰}$ and for hydrogen sulfide ?38.71 to $\text{?4.85‰}$. The distribution pattern for δ ³⁴S in both sulfate and sulfide appears to be the result of in situ sulfate reduction.  相似文献   

Oxygen consumption in the Eastern Mediterranean     

《Deep Sea Research Part I: Oceanographic Research Papers》2001,48(6):1535-1551

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Wave setup/setdown and longshore current on non-planar beaches     

W.G. McDougal  R.T. Hudspeth 《Coastal Engineering》1983,7(2):103-117

Wave-induced setup/setdown and longshore currents are examined theoretically for non-planar, concave-up beaches. A beach profile in which the still-water-depth is proportional to the horizontal distance offshore raised to the $\text{2}\text{3}$ power is examined in detail. The total mean-water-depth, which includes the sum of the still-water-depth for this $\text{2}\text{3}$ power beach profile plus the wave-induced setup/setdown, may be approximated shoreward of the breaker line in a best least-squares sense by a profile that is proportional to the horizontal distance offshore raised to the $\text{1}\text{2}$ power. The longshore current profile for this non-planar beach is found to differ significantly from that predicted analytically for a planar beach. The longshore current velocity does not vanish at the shoreline as in the planar beach case. In addition, the peak velocities and the total longshore transport of water are found to be less than for the corresponding planar beach cases. For a given concave-up beach profile, the influence of the lateral mixing increases as the wave height decreases.  相似文献   

Geochemistry of manganese deposits in relation to environment on the sea floor around southern Africa     

C.P. Summerhayes  J.P. Willis 《Marine Geology》1975,18(4):159-173

Manganese deposits from the Madagascar Basin, the Crozet Basin and the basins west of the Madagascar Ridge around southern Africa differ chemically from one another. This appears to be largely because of differences in the degree of oxygenation of the environment; most highly oxidizing is the Madagascar Basin, where the $\text{Mn}\text{Fe}$ ratio is very low and where the manganese deposits probably consist largely of “birnessite”.Continental-margin samples differ from basin samples in having higher $\text{Mn}\text{Fe}$ ratios, probably because of diagenetic remobilization processes within the sediment column. The ratios of Mn and Fe to certain metals ($\text{Mn}\text{Ni}$, $\text{Mn}\text{Zn}$, $\text{Fe}\text{Co}$ and $\text{Fe}\text{As}$) are the opposites of those found in other continental-margin environments, suggesting either a difference in the diagenetic process, or an additional metal source, off southern Africa. Both seawater and bottom sediments of the southern African margin are metal-enriched, and could act as sources of metals for growing manganese nodules and encrustations.  相似文献