Spectrofluorometric Applications in Studying Macroalgal Exudates*     

Jozo Dujmov  Perica Su evi&#x;  Boris Antoli&#x; 《Marine Ecology》1996,17(1-3):501-508

Abstract. In this paper we present a one-year investigation on the fluorescence characteristics of released products of selected Adriatic seaweeds. The technique chosen was UV-fluorescence spectroscopy with the synchronous mode, which involves the stepping of the excitation and emission monochromators. The five species, of representative macrophytes, Cystoseira compressa, Dictyopreris polypodioides, Gracilaria bursapastoris, Pterocladia capillacea, and Ulva rigida, were chosen on the basis of their dominance in the plant communities typical for the area near Split - Central Adriatic. Our results suggest that macroalgal-related dissolved fluorescent matter can be categorized into two distinct groups of fluorescing compounds with the following excitation wavelengths: one from 320–360 nm, probably for compounds with 2 fused aromatic rings, and another from 360–420 nm, corresponding with 3 & 4 fused rings. The contribution of aromatics with 2 and with 3 & 4 rings was very similar in the brown algae Cysroseira compressa and Dictyopteris polypodioides, while in the red algae Gracilaria bursapastoris and Pterocludia capillacea as well in the green alga Ulva rigida the group with 2 rings dominated.  相似文献   

Tracing terrigenous dissolved organic matter and its photochemical decay in the ocean by using liquid chromatography/mass spectrometry     

Thorsten Dittmar  Kenia Whitehead  Elizabeth C. Minor  Boris P. Koch 《Marine Chemistry》2007

Reversed-phase liquid chromatography/mass spectrometry (LC/MS) is introduced as a new molecular fingerprinting technique for tracing terrigenous dissolved organic matter (DOM) and its photochemical decay in the ocean. DOM along a transect from the mangrove-fringed coast in Northern Brazil to the shelf edge was compared with mangrove-derived porewater DOM exposed to natural sunlight for 2–10 days in a photodegradation experiment. DOM was isolated from all samples via solid-phase extraction (C18) for LC/MS analysis. DOM in the estuary and ocean showed a bimodal mass distribution with two distinct maxima in the lower m/z range from 400 to 1000 Da (intensity-weighted average of 895 Da). Terrigenous porewater DOM from the mangroves was characterized by a broad molecular mass distribution over the detected range from 150 to 2000 Da (intensity-weighted average of 1130 Da). Polar compounds, i.e., those that eluted early in the reversed-phase chromatography, absorbed more UV light and had on average smaller molecular masses than the more apolar compounds.  相似文献   

Mercury pollution in sediments,benthic organisms and inshore fishes of Haifa Bay,Israel     

Hava Hornung  Boris S Krumgalz  Yuval Cohen 《Marine environmental research》1984,12(3):191-208

Total mercury concentrations were determined in surficial sediments, eleven species of benthic organisms and six species of fish from Haifa Bay, Israel. The results show that essentially all of the shallow water zone of the Bay receives anthropogenic mercury. A mercury-cell chlor-alkali plant was identified as the source of pollution. Surficial sediments in the vicinity of the plant, containing up to 0·99 μg Hg/g dry weight, were up to 157 times enriched in mercury relative to an unpolluted area. Mercury levels in the benthic organisms reflected the levels in the sediments. Maximal concentrations reaching 38·7 and 18·2 μg Hg/g dry weight were found in the carnivorous gastropod molluscs Arcularia circumcinta and Arcularia gibbosula, respectively. In all fish species, specimens caught in Haifa Bay had higher mercury concentrations in the muscle tissue than specimens caught south of the Bay. A maximal value of 1·66 μg Hg/g wet weight was recorded in Diplodus sargus.  相似文献   

Thermogenic organic matter dissolved in the abyssal ocean   总被引：1，自引：2，他引：1  

Thorsten Dittmar  Boris P. Koch 《Marine Chemistry》2006,102(3-4):208-217

Formation and decay of thermogenic organic matter are important processes in the geological carbon cycle, but little is known about the fate of combustion-derived and petrogenic compounds in the ocean. We explored the molecular structure of marine dissolved organic matter (DOM) for thermogenic signatures in different water masses of the Southern Ocean. Ultrahigh-resolution mass spectrometry via the Fourier transform-ion cyclotron resonance technique (FT-ICR-MS) revealed the presence of polyaromatic hydrocarbons (PAHs) dissolved in the abyssal ocean. More than 200 different PAHs were discerned, most of them consisting of seven condensed rings with varying numbers of carboxyl, hydroxyl, and aliphatic functional groups. These unambiguously thermogenic compounds were homogenously distributed in the deep sea, but depleted at the sea surface. Based on the structural information alone, petrogenic and pyrogenic compounds cannot be distinguished. Surface depletion of the PAHs and first estimates for their turnover rate (> 1.2 · 10¹² mol C per year) point toward a primarily petrogenic source, possibly deep-sea hydrothermal vents, which is thus far speculative because the fluxes of combustion-derived and petrogenic matter to the ocean are not well constrained. We estimate that > 2.4% of DOM are thermogenic compounds, and their global inventory in the oceans is > 1.4 · 10¹⁵ mol C, significantly impacting global biogeochemical cycles.  相似文献   

Tracing suspended organic nitrogen from the Yangtze River catchment into the East China Sea   总被引：2，自引：0，他引：2  

Ying Wu  Thorsten Dittmar  Kai-Uwe Ludwichowski  Gerhard Kattner  Jing Zhang  Zhuo Y. Zhu  Boris P. Koch 《Marine Chemistry》2007

Total suspended matter was collected along the Yangtze River (Changjiang) and in the East China Sea in April to May and in September 2003, respectively, to study origin and fate of particulate organic nitrogen. Concentrations of particulate organic carbon (POC), nitrogen (PN) and hydrolyzable particulate amino acids (PAA; d- and l-enantiomers) were higher in the Yangtze Estuary than in the river and decreased offshore towards the shelf edge. In the coastal area, higher values of PAA were observed in the surface layer than in the bottom water. Stable carbon isotope ratios (δ¹³C) of POC increased from − 24.4‰ in the river to values around − 21‰ on the East China Sea Shelf. Dominant amino acids were aspartic acid + aspartine (Asx), glutamic acid + glutamine (Glx), glycine, alanine and serine. The proportions of Asx, Glx and isoleucine were higher in the marine than in the riverine samples contrary to the distributions of glycine, alanine, threonine and arginine. The proportions of d-amino acids were highest in the riverine suspended organic matter (6% of PAA) decreasing towards the shelf edge (1.5% of PAA). d-arginine, not reported in natural aquatic samples so far, was the most abundant d-amino acid in the river. The amino acid composition of the particulate organic matter (POM) in the Yangtze River indicates an advanced stage of degradation of POM. Highly degraded organic matter from soils is probably a main source of POM in the Yangtze River, but the relatively high δ¹³C values and low C/N ratios (7.7 ± 1.6) also indicate contribution from anthropogenic sources. The degraded riverine material was a dominant organic matter source in the estuary, where aquatic primary production had only a small overall contribution. In the East China Sea, gradual settling of riverine organic matter and the addition of fresher phytoplankton impacted the amino acid composition and δ¹³C values, and on the outer shelf relatively fresh phytoplankton-derived organic matter dominated.  相似文献   

A regional analysis of new production on the northwest European shelf using oxygen fluxes and a ship-of-opportunity     

Charlene P. Bargeron  David J. Hydes  David K. Woolf  Boris A. Kelly-Gerreyn  Mohammed A. Qurban 《Estuarine, Coastal and Shelf Science》2006,69(3-4):478

Seasonal new production (g C m⁻²) estimates obtained from dissolved oxygen and nitrate concentrations in surface waters (5 m depth) along a track between the UK (Portsmouth) and northern Spain (Bilbao) are compared. An oxygen flux method, in combination with a ship of opportunity (SOO), was tested on the northwest European shelf for its value in distinguishing high production in frontal regions. Dissolved oxygen, nitrate and chlorophyll a samples were collected monthly from February to July 2004, alongside continuous autonomous measurements of salinity, temperature and chlorophyll fluorescence. Depth integrated new production estimates for all the individually analysed hydrographic regions of the route were produced.Results from three widely used gas-exchange parameterizations gave seasonal (February–July) new production estimates of 54–68 g C m⁻² for the Ushant region of the western English Channel and 31–40 g C m⁻² for the shelf slope, averaging 24–31 g C m⁻² for the route. This is double the route average obtained using the nitrate assimilation method (17 g C m⁻²) and within the ranges of previous estimates in the same region. The oxygen flux method gave a fivefold enhancement compared to the nitrate method in the Ushant frontal region and a threefold enhancement in the English Channel and shelf break regions. Determining oxygen fluxes to estimate new production may be more reliable than nitrate assimilation in active tidal or frontal regions of shelves where nitrate may be added to the system post-winter through advection or entrainment.  相似文献   

On the Brown conjecture     

Boris Garfinkel 《Celestial Mechanics and Dynamical Astronomy》1984,34(1-4):459-463

In 1911 E. W. Brown conjectured that the family of long-periodic orbits in the Trojan case of the restricted problem of three bodies terminates in an asymptotic orbit that passes through the Langrangian point L₃ for t=±. The paper refutes this conjecture analytically, thereby confirming the previously published numerical refutation by Henrard (1983).  相似文献   

Victor Lyudvigovich Masaitis (July 21, 1927–July 21, 2019)     

Mikhail Naumov  Boris Ivanov  Alexander Deutsch  Falko Langenhorst 《Meteoritics & planetary science》2019,54(11):2879-2883

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Impacts of Kelvin wave forcing in the Peru Humboldt Current system: Scenarios of spatial reorganizations from physics to fishers   总被引：2，自引：1，他引：1  

Sophie Bertrand  Boris Dewitte  Jorge Tam  Erich Díaz  Arnaud Bertrand   《Progress in Oceanography》2008,79(2-4):278

Because climate change challenges the sustainability of important fish populations and the fisheries they support, we need to understand how large scale climatic forcing affects the functioning of marine ecosystems. In the Humboldt Current system (HCS), a main driver of climatic variability is coastally-trapped Kelvin waves (KWs), themselves originating as oceanic equatorial KWs. Here we (i) describe the spatial reorganizations of living organisms in the Humboldt coastal system as affected by oceanic KWs forcing, (ii) quantify the strength of the interactions between the physical and biological component dynamics of the system, (iii) formulate hypotheses on the processes which drive the redistributions of the organisms, and (iv) build scenarios of space occupation in the HCS under varying KW forcing. To address these questions we explore, through bivariate lagged correlations and multivariate statistics, the relationships between time series of oceanic KW amplitude (TAO mooring data and model-resolved baroclinic modes) and coastal Peruvian oceanographic data (SST, coastal upwelled waters extent), anchoveta spatial distribution (mean distance to the coast, spatial concentration of the biomass, mean depth of the schools), and fishing fleet statistics (trip duration, searching duration, number of fishing sets and catch per trip, features of the foraging trajectory as observed by satellite vessel monitoring system). Data sets span all or part of January 1983 to September 2006. The results show that the effects of oceanic KW forcing are significant in all the components of the coastal ecosystem, from oceanography to the behaviour of the top predators – fishers. This result provides evidence for a bottom-up transfer of the behaviours and spatial stucturing through the ecosystem. We propose that contrasting scenarios develop during the passage of upwelling versus downwelling KWs. From a predictive point of view, we show that KW amplitudes observed in the mid-Pacific can be used to forecast which system state will dominate the HCS over the next 2–6 months. Such predictions should be integrated in the Peruvian adaptive fishery management.  相似文献   

Early Neoproterozoic Granite-Gneisses of the Junggar Alataw (Southeastern Kazakhstan): Age, Petrogenesis and Tectonic Implications     

Nadezhda KANYGINA  Andrey TRETYAKOV  Dmitriy ALEXEIEV  Kirill DEGTYAREV  Anfisa SKOBLENKO  Natalia SOLOSHENKO  Boris ERMOLAEV 《《地质学报》英文版》2024,98(1):67-82

The combined petrographic, petrological, geochemical and geochronological study of the Neoproterozoic gneisses of the Sarychabyn and Baskan complexes of the Junggar Alataw of South Kazakhstan elucidate the Precambrian tectonic evolution of the Aktau–Yili terrane. It is one of the largest Precambrian crustal blocks in the western Central Asian orogenic belt. The U-Pb single-grain zircon ages indicate that granite-gneisses formed from the same source and crystallised in the early Neoproterozoic ca. 930–920 Ma. The chemical composition of gneisses corresponds to A2-type granites. The whole-rock Nd isotopic characteristics (εNd(t) = ?4.9 to ?1.0 and TNd(DM-2st) = 1.9 to 1.7 Ga) indicate the involvement of Paleoproterozoic crustal rocks in magma generation. Early Neoproterozoic ca. 930–920 Ma A-type granitoids in the Aktau–Yili terrane of South and Central Kazakhstan might reflect within-plate magmatism adjacent to the collisional belt or a local extension setting in back-arc areas of the continental arc.  相似文献