Particulate flux in the water column overlying Santa Monica Basin     

Michael R. Landry  Willis K. Peterson  Christine C. Andrews 《Progress in Oceanography》1992,30(1-4)

Fluxes of particulate carbon, nitrogen, phytoplankton pigments, biogenic silica and dry mass were measured using free-floating and moored sediment trap arrays in the Santa Monica Basin during the period from October 1985 to August 1990 as part of the California Basin Study (CaBS) Program. In field testing for potential sources of sediment trap biases, we found little significant or consistent difference in rate estimates between short-term drifting traps and long-term moored traps, between preserved and unpreserved traps in short-term experiments, between different preservatives (mercury or formalin) in long-term experiments, between different designs of small cylindrical traps, and between deep-moored cylindrical traps and large conical traps. We did, however, find that sediment trap samples collected and analyzed on 0.45 μm silver filters gave estimates of carbon and nitrogen fluxes about 25% higher than samples collected on GF/F glass-fiber filters. Concurrent trap deployments at two stations 18km apart revealed low mesoscale variability in flux estimates. Seasonal patterns in carbon and nitrogen flux were not evident in our data, but strong seasonality, with spring maxima and summer minima, were observed for fluxes of phaeopigments and biogenic silica out of the euphotic zone.Time-averaged rates of particulate flux for long-term trap deployments from January to August 1990, were 121, 18.8, 1.5, 67 and 633mg m⁻²d⁻¹ at 110–135m for carbon, nitrogen, phaeopigment, biogenic silica and mass, respectively. Flux estimates to the basin floor (835–860m) were 50, 6.5, 0.64, 41.6 and 575mg m⁻²d⁻¹ for the same parameters. The former estimates are constrained by and in good agreement with independent assessments of new production from nitrate uptake in the euphotic zone. The latter agree with rates previously inferred from the sedimentary record using ²¹⁰Pb as a tracer. In addition, the difference in carbon estimates in the water column between the euphotic zone and the basin floor is consistent with the requirements for bacterial growth and metabolism at intermediate depths as measured by the thymidine method.  相似文献   

A survey-based assessment of the Northeast Arctic cod stock     

Korsbrekke  Knut; Mehl  Sigbjorn; Nakken  Odd; Pennington  Michael 《ICES Journal of Marine Science》2001,58(4):763-769

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Geochemical characterization of the potential trace metal mobility in cohesive sediments     

Michael Kersten  Ulrich Förstner 《Geo-Marine Letters》1991,11(3-4):184-187

The Acid-Producing Potential (APP) and the Acid-Consuming Capacity (ACC) are introduced as basic parameters for long-term pollution assessment of mud disposal. They can be obtained by a four-step sequential leaching technique. The concentration of Ca extracted by the first Na-acetate step permits calculating the ACC. Both the Fe- and S-fractions deliberated by subsequent leaching steps are used to calculate the APP. When the APP of a sample is substacted from its ACC, a negative value indicates a potential increase of the bioavailability of the toxic metal load upon disposal of this mud in oxic environments.  相似文献   

Was a carbon balance measured in the equatorial Pacific during JGOFS?     

Paul Quay 《Deep Sea Research Part II: Topical Studies in Oceanography》1997,44(9-10)

The likelihood that the carbon fluxes measured as part of the US-JGOFS field program in the equatorial Pacific ocean (EgPac) during 1992 yielded a balanced carbon budget for the surface ocean was determined. The major carbon fluxes incorporated into a surface carbon budget were: new production, particulate organic carbon (POC) and dissolved organic carbon (DOC) export, CaC0₃ export, C0₂ gas evasion, dissolved inorganic carbon (DIC) supply, and the time rate of charge. The ratio of the measured concentration gradients of DOC and DIC provided a constraint on the ratio of POC/DOC export. Uncertainties of ±30–50% for individual carbon flux measurements reduce the likelihood that a carbon balance can be measured during a JGOFS process-type study. As a benchmark, carbon fluxes were prescribed to yield a hypothetical surface carbon budget that was, on average, balanced. Given the typical errors in the individual carbon fluxes, however, there was only about a 30% chance that this hypothetical budget could be measured to be balanced to ±50%. Using this benchmark, it was determined that there was a 95 % chance that the carbon flux measurements yielded a surface DIC budget balanced (to ±50%) during El Nino conditions in boreal spring 1992, when the total organic carbon export rate was - 5 mmol C m-2 day- 1 and the POC export was 3 mmol C m⁻² day⁻¹. In boreal fall 1992, during cold period conditions, there was a 70% chance that the surface carbon DIC budget was balanced when the total organic carbon export rate was 20 mmol C m⁻² day⁻¹ and export was -13 mmol C m-2 day-'. The DOC to DIC concentration gradient ratio of - -0.15, measured in depth profiles down to 100m and in surface waters, was used as an important constraint that most (> 70%) of the organic carbon exported from the euphotic zone was POC rather than DOC. If a balanced surface DIC budget was used to test the compatibility of individual carbon fluxes measured during EgPac, then a three- to four-fold increase in total and particulate organic carbon export between spring and fall is indicated. This increase was not reflected in the POC loss rates measured by drifting sediment trap collections or estimated by²³⁴Th deficiencies coupled with the C/Th measured on suspended particles.  相似文献   

Interannual variations in copepod nauplii prey of larval fish in an Alaskan Bay     

Paul  A. J.; Coyle  K. O.; Haldorson  L. 《ICES Journal of Marine Science》1991,48(2):157-165

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A proposed multiple-use zoning scheme for the Irish Sea.: An interpretation of current legislation through the use of GIS-based zoning approaches and effectiveness for the protection of nature conservation interests     

Suzanne J. Boyes  Michael Elliott  Shona M. Thomson  Stephen Atkins  Paul Gilliland 《Marine Policy》2007

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A community-wide intercomparison exercise for the determination of dissolved iron in seawater     

Andrew R. Bowie  Eric P. Achterberg  Peter L. Croot  Hein J.W. de Baar  Patrick Laan  James W. Moffett  Simon Ussher  Paul J. Worsfold 《Marine Chemistry》2006

The first large-scale international intercomparison of analytical methods for the determination of dissolved iron in seawater was carried out between October 2000 and December 2002. The exercise was conducted as a rigorously “blind” comparison of 7 analytical techniques by 24 international laboratories. The comparison was based on a large volume (700 L), filtered surface seawater sample collected from the South Atlantic Ocean (the “IRONAGES” sample), which was acidified, mixed and bottled at sea. Two 1-L sample bottles were sent to each participant. Integrity and blindness were achieved by having the experiment designed and carried out by a small team, and overseen by an independent data manager. Storage, homogeneity and time-series stability experiments conducted over 2.5 years showed that inter-bottle variability of the IRONAGES sample was good (< 7%), although there was a decrease in iron concentration in the bottles over time (0.8–0.5 nM) before a stable value was observed. This raises questions over the suitability of sample acidification and storage.  相似文献   

Empirical determination of in situ target strengths of three loosely aggregated pelagic fish species     

Barange  Manuel; Hampton  Ian; Soule  Michael 《ICES Journal of Marine Science》1996,53(2):225-232

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Histopathological changes in the liver of dab (Limanda limanda) from a contamination gradient in the North sea     

Michael G. Simpson 《Marine environmental research》1992,34(1-4)

As part of a joint workshop organised by the International Council for the Exploration of the Sea (ICES) and the Intergovernmental Oceanographic Commission (IOC) on biological effects monitoring techniques. dad (Limanda limanda) were examined from six spaced stations along a 200 km transect extending from near the mouth of the Elbe River out to the Dogger Bank in the North Sea. Based on historical data, differences in contaminant concentrations in sediments exist along the transect (lipophilic organic xenobiotics at the inshore sites and heavy metals offshore over the Dogger Bank). The most contaminated site sampled was the most inshore, the least contaminated was approximately midway along the transect, with contamination building up again over the farthest point along the transect, over the Dogger Bank. Multiple organs and tissues were examined for full pathology from each fish sampled. Only liver data are presented here (11–20 livers per station). The most significant lesions were considered to be well-developed foci of cellular alteration, high mitotic activity and high neutral lipid accumulation in livers from dab sampled from the most inshore site examined. Livers from the least-contaminated station showed minimal evidence of such changes. Foci of cellular alteration and neutral lipid accumulation were also seen in dab liver sampled from fish from the Dogger Bank site. Thus far, the hepatic changes seen correlate well with the most contaminated sites along the transect. The value of comprehensively examining the histopathology of an organ of toxicological significance, such as the liver in a European species of flatfish, is demonstrated.  相似文献   

Functional Molecular Biodiversity: Assessing the Immune Status of Two Sponge Populations (Suberites domuncula) on the Molecular Level     

Heinz C. Schröder  Vladislav A. Grebenjuk  Michael Binder  Alexander Skorokhod  Renato Batel  Hamdy Hassanein  & Werner E. G. Müller 《Marine Ecology》2004,25(2):93-108

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