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481.
T. Boski J. Pessoa P. Pedro J. Thorez J. M. A. Dias I. R. Hall 《Progress in Oceanography》1998,42(1-4)
Fifty-six samples representing 6 sediment cores taken along the N.W. European Continental Margin from the shelf, slope and abyssal plain of the Goban Spur and Meriadzek Terrace were quantitatively analysed for total hydrolyzable amino acids (THAA) and clay minerals. In descending order, the five most abundant amino acids making up more than 70% of the total were: aspartic acid, glycine, serine, alanine and glutamic acid. Clay mineral proportions were typical for the N.E. Atlantic, in order of descending abundance: illite, kaolinite, chlorite, smectite and mixed layers.The Meriadzek Terrace area is characterised by fine grain suspension sedimentation with a low pelagic carbonate input and the lowest content of THAA. In contrast, the Goban Spur transect is characterised by much higher carbonate inputs and more vigorous hydrodynamics as judged from granulometry and the high abundance of minerals of shelf and continental origin and a generally higher THAA content. The pelagic portion of THAA deposited at the sea floor is more readily mineralised during early diagenesis than the more ‘refractory', clay mineral-associated continental portion. Along this margin the average mineralization of THAA down to 25 cm in the sediment is about 54%. There is a significant affinity between chlorites and amino acids which we suggest may involve the formation of ionic bonds between the octahedral layers of the clay and the amino acids. 相似文献
482.
Benthic Nutrient Recycling in Port Phillip Bay, Australia 总被引:8,自引:0,他引:8
W.M. Berelson D. Heggie A. Longmore T. Kilgore G. Nicholson G. Skyring 《Estuarine, Coastal and Shelf Science》1998,46(6):917-934
Benthic chamber measurements of the reactants and products involved with biogenic matter remineralization (oxygen, ammonium, nitrate, nitrite, phosphate, silicate, TCO2and alkalinity) were used to define solute exchange rates between the sediment and overlying water column of Port Phillip Bay, Australia. Measurements at various sites throughout the bay, conducted during the summers of 1994 and 1995, indicate that the variability in flux values within a site is comparable to year-to-year variability (±50%). Four regions of the bay were distinguished by sediment properties and the northern region was identified as having 3–30 times greater nutrient regeneration rates than the other regions. Benthic recycling accounted for 63 and 72% of the annualized N and P input, respectively, to the entire bay as determined by summing benthic, dissolved riverine, atmospheric and dissolved effluent sources. However, bay-wide sedimentary denitrification accounted for a loss of 63% of the potentially recyclable N. This fraction is higher than many other coastal regions with comparable carbon loading. Denitrification efficiency is apparently not enhanced by benthic productivity nor by bio-irrigation. The rate of bio-irrigation is negatively correlated with denitrification efficiency. Bio-irrigation was studied using radon-222 and CsCl spike injection chamber measurements. Radon fluxes from sediments in Port Phillip Bay were enhanced over the diffusive flux by 3–16 times. The modelled rate of loss of Cs from chamber water was positively correlated with radon flux enhancement results. Both methods identify regions within Port Phillip Bay that have particularly high rates of non-diffusive pore-water overlying water solute exchange. 相似文献
483.
- In order to employ cost effective frequency domain analysis for off-shore structures treatment of hydrodynamic loading is essential. Drag and inertia dominated, resonating and antiresonating cases under random sea states are analyzed to highlight the implications and relative merits of four salient linearization techniques. 相似文献
484.
I. G. Boyarskikh S. A. Khudyaev S. G. Platonova S. P. Kolotukhin A. V. Shitov T. A. Kukushkina O. V. Chankina 《Izvestiya Atmospheric and Oceanic Physics》2012,48(7):747-760
Local geophysical and geochemical anomalies affect the polymorphism of taste variations, berry shape, and content of some biologically active substances in Lonicera caerulea leaves in the tectonically active Altai Mountains (Dzhazator River basin). 相似文献
485.
Oceanology - The paper examines the influence of the main mode of interannual variability of the North Atlantic climate system—the North Atlantic Oscillation (NAO)—on the hydrophysical... 相似文献
486.
Alekseeva T. A. Raev M. D. Tikhonov V. V. Sokolova J. V. Sharkov E. A. Frolov S. V. Serovetnikov S. S. 《Izvestiya Atmospheric and Oceanic Physics》2021,57(9):1076-1080
Izvestiya, Atmospheric and Oceanic Physics - The Arctic Sea ice area, calculated by the VASIA2 algorithm using the SSMIS data during the most intensive melting of the ice cover in 2019, is compared... 相似文献
487.
Pavlenko L. F. Barabashin T. O. Zhukova S. V. Korablina I. V. Anohina N. S. Klimenko T. L. Ekilik V. S. 《Oceanology》2022,62(1):59-67
Oceanology - The results of studies of oil pollution (by the sum of hydrocarbons and resinous substances) of water and bottom sediments in the northeast Black Sea in spring and autumn are... 相似文献
488.
Elansky N. F. Shilkin A. V. Ponomarev N. A. Zakharova P. V. Kachko M. D. Poliakov T. I. 《Izvestiya Atmospheric and Oceanic Physics》2022,58(1):80-94
Izvestiya, Atmospheric and Oceanic Physics - The location of Moscow on a plain within higher latitudes when compared to other megacities creates conditions for the chemical transformation of... 相似文献
489.
Methylmercury production in sediments of Chesapeake Bay and the mid-Atlantic continental margin 总被引:3,自引:0,他引:3
Methylmercury (MeHg) concentration and production rates were studied in bottom sediments along the mainstem of Chesapeake Bay and on the adjoining continental shelf and slope. Our objectives were to 1) observe spatial and temporal changes in total mercury (HgT) and MeHg concentrations in the mid-Atlantic coastal region, 2) investigate biogeochemical factors that affect MeHg production, and 3) examine the potential of these sediments as sources of MeHg to coastal and open waters. Estuarine, shelf and slope sediments contained on average 0.5 to 1.5% Hg as MeHg (% MeHg), which increased significantly with salinity across our study site, with weak seasonal trends. Methylation rate constants (kmeth), estimated using enriched stable mercury isotope spikes to intact cores, showed a similar, but weaker, salinity trend, but strong seasonality, and was highly correlated with % MeHg. Together, these patterns suggest that some fraction of MeHg is preserved thru seasons, as found by others [Orihel, D.M., Paterson, M.J., Blanchfield, P.J., Bodaly, R.A., Gilmour, C.C., Hintelmann, H., 2008. Temporal changes in the distribution, methylation, and bioaccumulation of newly deposited mercury in an aquatic ecosystem. Environmental Pollution 154, 77] Similar to other ecosystems, methylation was most favored in sediment depth horizons where sulfate was available, but sulfide concentrations were low (between 0.1 and 10 μM). MeHg production was maximal at the sediment surface in the organic sediments of the upper and mid Bay where oxygen penetration was small, but was found at increasingly deeper depths, and across a wider vertical range, as salinity increased, where oxygen penetration was deeper. Vertical trends in MeHg production mirrored the deeper, vertically expanded redox boundary layers in these offshore sediments. The organic content of the sediments had a strong impact on the sediment:water partitioning of Hg, and therefore, on methylation rates. However, the HgT distribution coefficient (KD) normalized to organic matter varied by more than an order of magnitude across the study area, suggesting an important role of organic matter quality in Hg sequestration. We hypothesize that the lower sulfur content organic matter of shelf and slope sediments has a lower binding capacity for Hg resulting in higher MeHg production, relative to sediments in the estuary. Substantially higher MeHg concentrations in pore water relative to the water column indicate all sites are sources of MeHg to the water column throughout the seasons studied. Calculated diffusional fluxes for MeHg averaged 1 pmol m− 2 day− 1. It is likely that the total MeHg flux in sediments of the lower Bay and continental margin are significantly higher than their estimated diffusive fluxes due to enhanced MeHg mobilization by biological and/or physical processes. Our flux estimates across the full salinity gradient of Chesapeake Bay and its adjacent slope and shelf strongly suggest that the flux from coastal sediments is of the same order as other sources and contributes substantially to the coastal MeHg budget. 相似文献
490.
Melanie Gammon Andrew Turner Murray T. Brown 《Estuarine, Coastal and Shelf Science》2009,84(4):447-452
The short-term (5 day) accumulation of Cu and Zn in different tissues of the marine gastropod, Littorina littorea, has been studied in the presence of 10 mg l−1 of antifouling paint particles and pre- or simultaneously contaminated algal food (Ulva lactuca). Accumulation of Cu was observed in the head–foot, digestive gland–gonad complex and gills to extents dependent on how and when food was contaminated and administered. However, retention of Zn was only observed in the gills and only when L. littorea and U. lactuca were simultaneously exposed to paint particles. Relative to the alga, faecal material was highly enriched in Zn, suggesting that the animal is able to rapidly eliminate this metal, most likely through the formation and egestion of insoluble phosphate granules. Thus, L. littorea is a useful biomonitor of marine contamination by antifouling applications in respect of Cu but not Zn. 相似文献