摘要:

In this paper, we use an inverse methodology to parameterize a box model of the Red Sea to study carbon exchanges and transport. In this application, we use simultaneously the information contained in physical and biogeochemical tracer profiles such as temperature, salinity, dissolved inorganic carbon, alkalinity, oxygen, and phosphate. Since the Red Sea is subject to a seasonal monsoon regime and because we are interested in resolving exchanges from the surface to the bottom, we have decoupled the temporal regime into two seasons : winter (November to May) and summer (June to October). We present the two solutions which include advective and mixing (eddy diffusion) exchanges as well as new primary production, decomposition, carbonate formation, and dissolution. The circulation is reversed from one season to the next. The net biological exchanges (new production) of carbon, compatible with the dynamical solutions, are almost null for the organic processes (negative in summer, positive in winter); the budgets for the mineral processes are negative for both seasons. This result is consistent with the view that carbonates play an important role in the budget of carbon in Red Sea. Finally, taking advantage of richer data sets for the summer season, we present two box designs for this period. It appears that transport solutions are sensitive to the choice of box topology, whereas biochemical exchanges are roughly the same for both designs.

ISSN:0886-6236    

DOI:10.1029/GB003i001p00001

年代:1989

数据来源: WILEY

摘要:

Size separations of phytoplankton biomass and production were performed with Nuclepore filters in the central and eastern tropical Pacific. The results show that there is a relationship between size and distance from land forms, with larger aggregates of phytoplankton dominating close to shore and small (less than 1 μm) forms dominating offshore. Surface nutrient concentrations were high in the offshore regions of equatorial upwelling and there was no apparent relationship between nutrient concentration and size. The phytoplankton biomass and production in the equatorial Pacific from 90°W to 150°W are dominated by small algae which are not retained by 5 μm Nuclepore filters with these organisms accounting for over 80% of the biomass and production. It is hypothesized that the dominance of small forms, as well as the relatively low plant biomass found, is the result of the absence of neritic bloom‐forming centric diatoms in offshore regions. The fact that small phytoplankton dominate in the equatorial Pacific suggests a dynamic food web. A dynamic food web coupled with the vigorous horizontal circulation of the equatorial Pacific supports the notion that some of the new nitrogen upwelled in this region is first exported laterally and then verti

ISSN:0886-6236    

DOI:10.1029/GB003i001p00027

年代:1989

数据来源: WILEY

摘要:

The air‐sea exchange of trace gases is critical in modeling the evolution of the compositional changes of the Earth's atmosphere on a variety of time scales. This exchange is controlled by the transfer velocity (Kw) and the air‐sea concentration gradient. The interplay between the transfer velocity and extent of local surface ocean CO2saturation influences the partitioning of carbon and its isotopes between the atmosphere and ocean. Here, the present‐day global transfer velocity field of CO2is computed for January and July with user‐defined derived fields based on control runs of the NCAR (National Center for Atmospheric Research) CCMl (Community Climate Model), a 12‐layer atmospheric general circulation model. The spatial resolution of these calculations is 4.5° × 7.5° latitude‐longitude. The range of KwCO2variation over the globe is an order of magnitude, varying from 3 to 40 cm h−1. Equatorial values are generally 3–10 cm h−1and high latitude regions experience values in excess of 30 cm h−1. The annual variability of the transfer velocity for CO2in the high‐latitude northern hemisphere is larger than in the high‐latitude southern hemisphere. The global area‐weighted CO2transfer velocity for both January and July runs is roughly a factor of 1.8

ISSN:0886-6236    

DOI:10.1029/GB003i001p00037

年代:1989

数据来源: WILEY

摘要:

To study the temporal variability of oceanic productivity, time series particle fluxes were monitored at pelagic Station Papa (50°N, 145°W) in the eastern subarctic Pacific from September 1982 through August 1986. Automated Particle Flux (PARFLUX) time series sediment traps were deployed at 3800 m and 1000 m in the 4200‐m deep pelagic ocean. The traps collected samples for 2‐week periods for an almost continuous 4‐year‐long particle flux record. In order to study spatial flux variability, an additional trap at Station C (49.5°N, 138°W) was occupied during 1985‐1986 where particle fluxes were measured at 3500 m in the 3900‐m deep water. Time series flux samples from Station C were synchronized with those at Station Papa for comparison with each other. In order to evaluate their value as productivity or temperature indicators, species of silicoflagellates andActiniscus, a dinoflagellate genus with siliceous endoskeletons, were examined from the time series trap samples. Their fluxes were enumerated for a total of 119 samples from Station Papa and 24 samples from Station C. Among seven silicoflagellate taxa,Distephanus speculumandDictyocha mandraiwere dominant taxa which constantly represented>70 % of total silicoflagellate assemblages. All of the taxa showed significantly suppressed fluxes during 1984 which were correlated with the σtchanges centered around 100 m depth. It is hypothesized that the suppressed fluxes were attributable to a decrease in convective nutrient (or trace elements) supply. The flux ofDistephanus speculum, a productivity indicator, was negatively correlated with the diversity index of silicoflagellates which is considered to be another productivity measure. Seasonal patterns ofD. speculumandD. mandraipercentages also follow patterns ofD. speculumflux and silicoflagellate diversity, either parallel or inversely. Thus,D. speculumflux trends, diversity indices and percent contribution to silicoflagellate assemblages reflect variability in upper water silicoflagellate production rate which is a consequence of hydrographic conditions. It is concluded that Stations Papa and C, 600 km apart, are situated in the same oceanic province with similar ecosystems. This is based on their exhibiting the same species composition, and very similar seasonal patterns of fluxes, and the percentages of species in the assemblages from the two stations. Most silicoflagellate species fluxes at Station C were approximately one half of those measured at Station Papa which can be explained by differences in upper water σtvalues relative those below 200 m. Thus, silicoflagellate data clearly suggested lower fertility of the upper waters at Station C than that at Station Papa. Flux maxima at Station C generally lagged behind Station Papa by two weeks, resulting from lower σtat values in the seasonal mixed layer. The importance of silicoflagellate fluxes as an indicator of seasonal mixed layer σtis demonstrated in the regional comparisons of fluxes and hydrography. Generic ratios ofDictyocha/Distephanuswere more dependent on production rates than temperature, on the contrary to a previous hypothesis in the literature. Apparent correlations between the ratios and temperatures which were obtained in previous basin‐wide studies may be indirect results of the fertility of upper water masses which are in part governed by temperature and hence stability of the wat

ISSN:0886-6236    

DOI:10.1029/GB003i001p00043

年代:1989

数据来源: WILEY

摘要:

Overall budgets for nutrient and humus are described for the Baltic Sea as well as for the subsystems, i.e., the Baltic proper, the Bothnian Bay and the Bothnian Sea. The residence times for total phosphorus, total nitrogen, silicate and humus are 13.3, 5.5, 11.2 and 9.6 years respectively, compared to 21.8 years for a conservative substance (salt). About 90% of the nutrient losses are due to biogeochemical sinks within the Baltic Sea. Thus only about 10% is exported to external areas (the Kattegat/Belt Sea). For humus the corresponding figures are about 75 and 25%, respectively. This means that the Baltic Sea to a large extent can be regarded as a closed system and perturbations in the water exchange with the North Sea should have little effect on the nutrient budgets. The sinks are parameterized by an expression borrowed from limnology where the net nutrient loss is a function of the winter surface concentration. A budget model is run in a prognostic, hindcast mode with the assumed time‐dependent phosphorus and nitrogen loading of the Baltic proper. The computed development of the winter surface concentrations of total P and total N for the period 1950‐1988 appears quite realistic. The possibility of having variable sinks which are functions of the surface winter concentrations of nitrogen and phosphorus is described using calculations based on data from the different Baltic subareas. Such sinks should significantly decrease the winter N:P ratio in the surface water when the nutrient loading increases with time. With better descriptions of in particular the pools of nutrients in the sediment, it would be possible to model future changes of nutrient concentrations in the water column in relation to load

ISSN:0886-6236    

DOI:10.1029/GB003i001p00063

年代:1989

数据来源: WILEY

摘要:

Hydrographic profiles of inorganic germanium and silica in the western Indian Ocean confirm the silicalike behavior of inorganic germanium in seawater. Combining all existing oceanic data (Indian, Atlantic, Pacific, Bering Sea and Antarctic), these new data provide an improved oceanic Ge to Si relationship: Ge(pM) = 0.699±0.004 × Si(μM) + 3.6±0.4. Simple box models of the ocean demonstrate that the positive Ge intercept in this relationship results from biological fractionation of the Ge/Si ratio: Siliceous organisms discriminate against germanium during production of biogenic opal. This result is confirmed by (Ge/Si)Opalanalyses of diatoms and radiolaria separated from siliceous oozes of Holocene core tops. A rapid rise in diatom‐(Ge/Si)Opalrecorded in an Antarctic piston core over the interval from the Last Glacial (18 thousand years before present) to the Holocene (present) suggests that biosiliceous productivity was lower and preformed silica concentrations were higher in Southern Ocean surface waters during glacial

ISSN:0886-6236    

DOI:10.1029/GB003i001p00079

年代:1989

数据来源: WILEY

摘要:

The organic sulfur content of suspended and sinking particulate matter was examined in the upper 1000 m of the water column in the Southern California Bight. Depth distributions of suspended particulate organic sulfur (POS) showed a subsurface maximum in most stations that deepened offshore. POS concentrations in suspended matter averaged 1.26 ± 0.50 μg S L−1within the euphotic zone during the two cruises analyzed (August and October, 1987). The downward fluxes of mass, carbon, nitrogen and sulfur of sinking particulate matter increased with increasing sample depth to 350 m in the water column. Fluxes were similar during the three deployments. POS was correlated with and directly proportional to POC, PON, and chlorophyllain the suspended material. Similar correlations were obtained in the trap material although a positive POC intercept value suggested the presence of more refractory material, with sulfur being selectively removed relative to carbon. The average molar ratios were C : N : S = 224 : 27: 1 in suspended and 119 : 17 : 1 in sinking particulate organic matter. Particulate organic sulfur appeared to have a biological origin, most likely plankto

ISSN:0886-6236    

DOI:10.1029/GB003i001p00089

年代:1989

数据来源: WILEY