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81.
Lisa E. Collins William BerelsonDouglas E. Hammond Angela Knapp Richard SchwartzDoug Capone 《Deep Sea Research Part I: Oceanographic Research Papers》2011,58(8):898-914
Moored sediment traps were deployed from January 2004 through December 2007 at depths of 550 and 800 m in San Pedro Basin (SPB), CA (33°33.0′N, 118°26.5′W). Additionally, floating sediment traps were deployed at 100 and 200 m for periods of 12-24 h during spring 2005, fall 2007, and spring 2008. Average annual fluxes of mass, particulate organic carbon (POC), ??13Corg, particulate organic nitrogen (PON), ??15N-PON, biogenic silica (bSiO2), calcium carbonate (CaCO3), and detrital material (non-biogenic) were coupled with climate records and used to examine sedimentation patterns, vertical flux variability, and organic matter sources to this coastal region. Annual average flux values were determined by binning data by month and averaging the monthly averages. The average annual fluxes to 550 m were 516±42 mg/m2 d for mass (sdom of the monthly averages, n=117), 3.18±0.26 mmol C/m2 d for POC (n=111), 0.70±0.05 mmol/m2 d for CaCO3 (n=110), 1.31±0.21 mmol/m2 d for bSiO2 (n=115), and 0.35±0.03 mmol/m2 d for PON (n=111). Fluxes to 800 and to 550 m were similar, within 10%. Annual average values of ??13Corg at 550 m were −21.8±0.2‰ (n=108), and ??15N averages were 8.9±0.2‰ (n=95). The timing of both high and low flux particle collection was synchronous between the two traps. Given the frequency of trap cup rotation (4-11 days), this argues for particle settling rates ≥83 m/d for both high and low flux periods. The moored traps were deployed over one of the wettest (2004-2005, 74.6 cm rainfall) and driest (2006-2007, 6.6 cm) rain years on record. There was poor correlation (Pearson's correlation coefficient, 95% confidence interval) of detrital mass flux with: Corg/N ratio (r=0.10, p=0.16); ??15N (r=−0.19, p=0.02); and rainfall (r=0.5, p=0.43), suggesting that runoff does not immediately cause increases in particle fluxes 15 km offshore. ??13Corg values suggest that most POC falling to the basin floor is marine derived. Coherence between satellite-derived chlorophyll a records from the trap location (±9 km2 resolution) and SST data indicates that productivity and export occurs within a few days of upwelling and both of these parameters are reasonable predictors of POC export, with a time lag of a few days to 2 weeks (with no time lag—SeaWiFS chlorophyll a and POC flux, r=0.25, p=0.0014; chlorophyll a and bSiO2 flux, r=0.28, p=0.0002). 相似文献
82.
The hepatic mixed function oxidase system in the fish differs from that in mammals in its responses to the two classic mammalian inducers. The cytochrome P-448-type inducers (polycyclic aromatic hydrocarbons) stimulate monooxygenase activity, but phenobarbital, a P-450-type inducer, does not.1 We have compared the effects of phenobarbital (PB) and polychlorinated biphenyls (PCB) on the turnover of hepatic microsomal hemoproteins in trout (PCB's are P-448- and P-450-type inducers in mammals, which in fish induce only cytochrome P-448). We show here that neither PCB nor PB treatment changed the turnover rate. However, both the rates of synthesis and degradation were much slower than in the rat. 相似文献
83.
Carbon balance in a salt marsh: Interactions of diffusive export, tidal deposition and rainfall-caused erosion 总被引:1,自引:0,他引:1
Alice G. Chalmers Richard G. Wiegert Paul L. Wolf 《Estuarine, Coastal and Shelf Science》1985,21(6):757-771
Studies of the concentrations of particulate and dissolved organic carbon in the Duplin River, of the tidal exchange of POC and DOC in the marsh, of the standing stock and movement of Spartina alterniflora wrack in the Duplin, and of the removal of carbon from the surface of the marsh by rain were conducted at Sapelo Island, Georgia in order to test three hypotheses about export of carbon from the Duplin River watershed. We found that the gradients in POC and DOC concentrations are such that carbon is being transported down the Duplin River throughout the year, although in smaller quantities than previously believed. In contrast, almost all tidal exchanges within the marsh result in deposition of carbon. Most of this deposited carbon is subsequently eroded as a result of rain falling on the exposed marsh surface, and is washed back into the tidal creeks. This cycle of deposition and erosion is a possible mechanism keeping POC in the thin aerobic surface layer of the marsh, thus increasing its availability to detritivores and aerobic microbes. The standing stock of wrack is only a fraction of the S. alterniflora produced each year, and its export is a negligible term in the carbon balance equation. 相似文献
84.
85.
A basalt outcrop was discovered on Alderdice Bank on the outer Louisiana continental shelf. The basalt shows an age of 76.8 ± 3.3 × 106 years. Textural, mineralogical, and chemical characteristics indicate that it is an alkali basalt of shallow intrusive origin. It was probably brought to the seafloor by salt tectonics and exposed due to salt dissolution.An accurate account of the Mesozoic geologic history of the Gulf of Mexico must consider the apparent consanguinity of all magmatic rocks of the region, including the Alderdice Bank basalt, and the apparent basinward decrease in age of magmatic activities. 相似文献
86.
Taro Takahashi Stewart C. Sutherland Rik Wanninkhof Colm Sweeney Richard A. Feely David W. Chipman Burke Hales Gernot Friederich Francisco Chavez Christopher Sabine Andrew Watson Dorothee C.E. Bakker Ute Schuster Nicolas Metzl Hisayuki Yoshikawa-Inoue Masao Ishii Takashi Midorikawa Yukihiro Nojiri Arne Krtzinger Tobias Steinhoff Mario Hoppema Jon Olafsson Thorarinn S. Arnarson Bronte Tilbrook Truls Johannessen Are Olsen Richard Bellerby C.S. Wong Bruno Delille N.R. Bates Hein J.W. de Baar 《Deep Sea Research Part I: Oceanographic Research Papers》2009,56(11):2075-2076
87.
Andrew J.P. Harwood Paul F. Dennis Alina D. Marca Graham M. Pilling Richard S. Millner 《Estuarine, Coastal and Shelf Science》2008
Based on measurements of the 18O isotope composition of 247 samples collected over a 3-year period we have assessed the oxygen isotope composition of water masses in the North Sea. This is the first δ18O data set that covers the entire North Sea basin. The waters lie on a mixing line: δ18O (‰VSMOW) = −9.300 + 0.274(S) with North Atlantic sub-polar mode water (SPMW) and surface waters, and Baltic Sea water representing the saline and freshwater end members respectively. Patterns exhibited in surface and bottom water δ18O distributions are representative of the general circulation of the North Sea. Oxygen-18 enriched waters from the North Atlantic enter the North Sea between Scotland and Norway and to a lesser extent through the English Channel. In contrast, oxygen-18 depleted waters mainly inflow from the Baltic Sea, the rivers Rhine and Elbe, and to a lesser degree, the Norwegian Fjords and other river sources. Locally the δ18O–salinity relationship will be controlled by the isotopic composition of the freshwater inputs. However, the range of local freshwater compositions around the North Sea basin is too narrow to characterise the relative contributions of individual sources to the overall seawater composition. This dataset provides important information for a number of related disciplines including biogeochemical research and oceanographic studies. 相似文献
88.
Suzan S. Pool Richard D. Brodeur N. Lynn Goodman Elizabeth A. Daly 《Estuarine, Coastal and Shelf Science》2008
The Juan de Fuca Eddy is a seasonal, counter-clockwise gyre off the mouth of the Strait of Juan de Fuca between Washington, USA and British Columbia, Canada that may provide favorable feeding habitat for juvenile coho salmon (Oncorhynchus kisutch) during their early marine existence. In late September 2002, physical and biological sampling was conducted along two transects of the eddy region. Surface rope trawling was conducted to capture juvenile salmon and other nekton, along with bongo and neuston net tows to examine potential mesozooplanktonic salmon prey. Presence of the Juan de Fuca Eddy was confirmed with vertical water profiles. In addition, nutrient and chlorophyll a concentrations collected from 3-m depth were within the range observed in previous studies within the eddy region. In the mesozooplankton community, euphausiids, chaetognaths, and decapod megalopae were common. In the diet of juvenile coho salmon, euphausiids and decapod megalopae were dominant by percent number, and larval and juvenile fish were dominant by percent weight. Feeding intensity (percent body weight) based on stomach contents was variable, but not significantly different among stations. To compare the Juan de Fuca Eddy region with an upwelling area, we sampled along a transect off La Push (LP), Washington, USA which is south of the eddy. The eddy region was found to be less productive than the LP transect. Nutrients were lower, chlorophyll a concentrations were higher, and zooplankton abundance was generally higher along the LP transect than in the eddy region. In addition, more juvenile coho salmon were captured from the LP transect than the eddy region. Prey items in stomachs of salmon from the LP transect were heterogeneous compared to those from the eddy region. Feeding intensity along the LP transect was slightly lower and more variable than in the eddy region, and differences in feeding intensity among LP stations were significant. In addition, feeding intensities among stations nested within regions were significantly different. 相似文献
89.
Jessica L. Bangma Richard L. Haedrich 《Deep Sea Research Part II: Topical Studies in Oceanography》2008,55(24-26):2594
We quantify the similarity of the Gulf of Mexico mesopelagic fish fauna to that in adjacent oceanic regions, the Venezuelan and Colombian Basins of the Caribbean Sea and the North and South Sargasso Seas. The South Sargasso and Colombian are the least similar of the areas in terms of their faunal composition, and the Venezuelan and Colombian Basins are the most similar. The Gulf fauna lies somewhere in between, and is a composite of that in the Sargasso and Caribbean Seas. The Gulf of Mexico displays the greatest abundance, biomass and richness (S=140 species), and is an intermediate in evenness (J=0.66) and percent endemism (7.1%). Our findings support the view that the centrally located Gulf is an oceanic ecotone between the Atlantic Tropical and Subtropical faunal regions. 相似文献
90.
T. Richard Seaborne 《Marine and Petroleum Geology》1996,13(8):963-972
The Shabwa Basin is the northeastern extension of the Marib-Al Jawf-Shabwa system of Mesozoic grabens, located onshore in the Republic of Yemen. An evaporitic sequence with an estimated maximum depositional thickness of 300 metres was deposited during the Tithonian. It is designated the Sabatayn Formation and exerts significant control on most of the play elements in the principal hydrocarbon play systems anticipated in the northeastern part of the basin. Migration of hydrocarbons from pre-salt source rocks into intra-and post-salt reservoirs is restricted by the evaporites. Localised heat flow perturbations introduced by the salt, increase the maturity of post-salt source rocks. Post and intra-salt reservoirs are structured by listric faulting on a salt detachment, salt pillowing due to post-depositional loading, by local salt dissolution and by late folding due to gravity sliding of the post-salt section on a salt detachment. Early dissolution and reprecipitation of salt is responsible for occlusion of porosity in intra-salt clastic reservoirs. 相似文献