Diel Aquatic CO<Subscript>2</Subscript> System Dynamics of a Bermudian Mangrove Environment     

John A. Zablocki  Andreas J. Andersson  Nicholas R. Bates 《Aquatic Geochemistry》2011,17(6):841-859

Mangrove ecosystems play an important, but understudied, role in the cycling of carbon in tropical and subtropical coastal ocean environments. In the present study, we examined the diel dynamics of seawater carbon dioxide (CO₂) and dissolved oxygen (DO) for a mangrove-dominated marine ecosystem (Mangrove Bay) and an adjacent intracoastal waterway (Ferry Reach) on the island of Bermuda. Spatial and temporal trends in seawater carbonate chemistry and associated variables were assessed from direct measurements of dissolved inorganic carbon, total alkalinity, dissolved oxygen (DO), temperature, and salinity. Diel pCO₂ variability was interpolated across hourly wind speed measurements to determine variability in daily CO₂ fluxes for the month of October 2007 in Bermuda. From these observations, we estimated rates of net sea to air CO₂ exchange for these two coastal ecosystems at 59.8 ± 17.3 in Mangrove Bay and 5.5 ± 1.3 mmol m⁻² d⁻¹ in Ferry Reach. These results highlight the potential for large differences in carbonate system functioning and sea-air CO₂ flux in adjacent coastal environments. In addition, observation of large diel variability in CO₂ system parameters (e.g., mean pCO₂: 390–2,841 μatm; mean pH_T: 8.05–7.34) underscores the need for careful consideration of diel cycles in long-term sampling regimes and flux estimates.  相似文献   

Modelling thermal transients from magmatic underplating—an example from the Vøring margin (NE Atlantic)     

Magnus Wangen  Rolf Mjelde  Jan Inge Faleide 《Computational Geosciences》2011,15(4):771-788

The thermal impact of several kilometre-thick magmatic underplating in the lower continental crust is studied with analytical and numerical methods. Simple analytical solutions are derived for the thermal transient in the case of an infinite depth below the underplate and also for the case of a finite depth (down to the asthenosphere). It is shown that these solutions lead to simple approximations for when the transient surface heat flow is at its maximum, what the maximum is, and for how long the transient lasts. Even though these solutions assume that the underplate is emplaced instantaneously, they are useful in the interpretation of underplating over finite time spans. A numerical scheme is suggested for the modelling of underplating that handles both short time intervals as well as long intervals. The scheme treats magmatic underplating in a mass and energy conservative manner, and it is compared against the analytical solutions. Finally, the analytical and numerical results for thermal transients are applied to a transect from the Vøring margin (NE Atlantic), with respect to various degrees of early Cenozoic magmatic intrusion. It appears that more than half of the lower crustal body (LCB) in the Vøring margin must be magmatic underplating for the vitrinite reflectance to be substantially higher than for the non-magmatic case, where the LCB is assumed to comprise Caledonian crust.  相似文献   

The Late Cretaceous Klepa basalts in Macedonia (FYROM)—Constraints on the final stage of Tethys closure in the Balkans          下载免费PDF全文

Dejan Prelević  Simon Wehrheim  Magnus Reutter  Rolf L. Romer  Blažo Boev  Milica Božović  Paul van den Bogaard  Vladica Cvetković  Stefan M. Schmid 《地学学报》2017,29(3):145-153

The waning stage(s) of the Tethyan ocean(s) in the Balkans are not well understood. Controversy centres on the origin and life‐span of the Cretaceous Sava Zone, which is allegedly a remnant of the last oceanic domain in the Balkan Peninsula, defining the youngest suture between Eurasia‐ and Adria‐derived plates. In order to investigate to what extent Late‐Cretaceous volcanism within the Sava Zone is consistent with this model we present new age data together with trace‐element and Sr–Nd–Pb isotope data for the Klepa basaltic lavas from the central Balkan Peninsula. Our new geochemical data show marked differences between the Cretaceous Klepa basalts (Sava Zone) and the rocks of other volcanic sequences from the Jurassic ophiolites of the Balkans. The Klepa basalts mostly have Sr–Nd–Pb isotopic and trace‐element signatures that resemble enriched within‐plate basalts substantially different from Jurassic ophiolite basalts with MORB, BAB and IAV affinities. Trace‐element modelling of the Klepa rocks indicates 2%–20% polybaric melting of a relatively homogeneously metasomatised mantle source that ranges in composition from garnet lherzolite to ilmenite+apatite bearing spinel–amphibole lherzolite. Thus, the residual mineralogy is characteristic of a continental rather than oceanic lithospheric mantle source, suggesting an intracontinental within‐plate origin for the Klepa basalts. Two alternative geodynamic models are internally consistent with our new findings: (1) if the Sava Zone represents remnants of the youngest Neotethyan Ocean, magmatism along this zone would be situated within the forearc region and triggered by ridge subduction; (2) if the Sava Zone delimits a diffuse tectonic boundary between Adria and Europe which had already collided in the Late Jurassic, the Klepa basalts together with a number of other magmatic centres represent volcanism related to transtensional tectonics.  相似文献   

A non‐collisional,accretionary Sveconorwegian orogen – Comment     

Charlotte Möller  Bernard Bingen  Jenny Andersson  Michael B. Stephens  Giulio Viola  Anders Scherstén 《地学学报》2013,25(2):165-168

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Effects of pulp bleach plant effluents on hepatic xenobiotic biotransformation enzymes in fish: Laboratory and field studies     

L. Frlin  T. Andersson  B.-E. Bengtsson  J. Hrdig  . Larsson 《Marine environmental research》1985,17(2-4)

The present preliminary report on studies of the influence of pulp bleach plant effluents on hepatic biotransformation enzymes in fish is a part of a major characterisation of biochemical and physiological effects of effluents from pulp industries in Sweden. Our studies on the xenobiotic biotransformation enzymes demonstrate, so far, that the pulp effluents have the potential to strongly induce 7-ethoxyresorufin-O-deethylase activity (EROD) in fish liver and that fish living in the receiving water of an effluent from a pulp bleach plant have induced hepatic EROD activities as well as higher hepatic UDP glucuronyltransferase activities than those living in an unpolluted area. It is thus apparent that measures of induction of biotransformation enzymes in fish liver may be a useful approach in monitoring the presence of potential hazardous compounds released from pulp industries.  相似文献   

Size distribution of colloidal trace metals and organic carbon during a coastal bloom in the Baltic Sea   总被引：1，自引：0，他引：1  

Johan Ingri  Susanna Nordling  Jenny Larsson  Jenny Rnnegrd  Nina Nilsson  Ilia Rodushkin  Ralf Dahlqvist  Per Andersson   rjan Gustafsson 《Marine Chemistry》2004,91(1-4):117-130

The physico-chemical speciation of organic carbon and selected metals was measured during a coastal bloom in Ekhagen Bay, Baltic Sea, using ultrafiltration.One important objective with the study was to see if any depletion of trace metals could be measured in the directly bioavailable fraction (<1000 Da, the soluble low molecular weight fraction, LMW) during a plankton bloom. Filters with five different cut-offs were used (1 kD (1000 Da), 5 kD, 10 kD, 100 kD and 0.22 μm) in order to delineate the size distribution of colloidal organic carbon (COC) and trace metals.During the bloom in May, LMW Al, Co, Cu, Mn and Ni concentrations decreased although the colloidal and particulate concentrations were relatively high. Data show that desorption of colloidal and particulate bound trace metals to the LMW fraction was slower than the process depleting the LMW fraction.Estimates of the maximum active uptake of Cu, Ni and Mn by the phytoplankton, and the loss of non-bioactive Al from the LMW fraction, indicate that processes other than active uptake by phytoplankton must contribute to the observed depletion of trace metals in the LMW fraction. Hence, in order to estimate the bioavailable pool of trace metals for plankton during bloom conditions, these other processes must be understood and quantified.Transparent Exopolymeric Particles (TEP, reflecting sugar-rich phytoplankton exudates) increased around eight times during the plankton bloom. We hypothesize that the formation of TEP is a process that might be important for the transfer of trace metals from the LMW to the particulate fraction during the phytoplankton bloom, but the significance of TEP for this depletion in Baltic Sea surface water remains to be shown.  相似文献   

The POC / Th ratio of settling particles isolated using split flow-thin cell fractionation (SPLITT)     

rjan Gustafsson  Jenny Larsson  Per Andersson  Johan Ingri 《Marine Chemistry》2006,100(3-4):314

The common assumption that the ratio between particulate organic carbon (POC) and particulate ²³⁴Th obtained from shallow sediment traps and filterable particles are representative of the ratio in the total particle settling flux should be treated with caution in view of well-known biases associated with tethered shallow sediment traps and the decoupling between size and settling velocity of many natural particle regimes. To make progress toward reliably constraining the POC / ²³⁴Th ratio on truly settling particles, we have tested here a settling collection technique designed to remove any hydrodynamic bias; split flow-thin cell fractionation (SPLITT). These first results from a North Sea fjord and an open Baltic Sea time-series station indicates that the POC / ²³⁴Th ratio on the more complete particle-settling spectrum, isolated with SPLITT, was higher than the POC / ²³⁴Th ratio obtained simultaneously from tethered shallow sediment traps in seven out of seven parallel deployments with an average factor of 210%. The POC / ²³⁴Th ratio from the SPLITT was either in the same range or higher than that obtained on filtered “bulk” particles. To explain this novel data we hypothesize that the slowest settling fraction is organic-matter rich and does not strongly complex ²³⁴Th (i.e., high POC / ²³⁴Th). We suggest that this ultra-slow sinking fraction is better collected by SPLITT than with tethered sediment traps because of minimized hydrodynamic bias.This was tested using the ratio of POC / Al as a tracer of detrital mineral-ballast influenced settling velocity. The higher POC / Al ratios in SPLITT samples relative to in traps is consistent with the hypothesis that SPLITT is better suited for collecting also the slow-settling component of sinking particles. This important slow-settling component appears to here consist primarily of non-APS/TEP components of plankton exudates or other less-strongly ²³⁴Th-complexing organic matter. Further applications of the SPLITT technique are likely to return increasingly new insights on the composition (including “truly settling” POC / ²³⁴Th) of the total spectrum of particles settling out of the upper ocean.  相似文献   

Lagrangian perturbation theory for rotating magnetic stars     

Kostas Glampedakis  Nils Andersson 《Monthly notices of the Royal Astronomical Society》2007,377(2):630-644

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Enhanced concentrations of dissolved gaseous mercury in the surface waters of the Arctic Ocean   总被引：2，自引：0，他引：2  

M.E. Andersson  J. Sommar  K. Grdfeldt  O. Lindqvist 《Marine Chemistry》2008,110(3-4):190-194

During an almost three months long expedition in the Arctic Ocean, the Beringia 2005, dissolved gaseous mercury (DGM) was measured continuously in the surface water. The DGM concentration was measured using an equilibrium system, i.e. the DGM in the water phase equilibrated with a stream of gas and the gas was thereafter analysed with respect to its mercury content. The DGM concentrations were calculated using the following equation, DGM = Hg_eq / k_H' where Hg_eq is the equilibrated concentration of elemental mercury in the gas phase and k_H' is the dimensionless Henry's law constant at desired temperature and salinity. During the expedition several features were observed. For example, enhanced DGM concentration was measured underneath the ice which may indicate that the sea ice acted as a barrier for evasion of mercury from the Arctic Ocean to the atmosphere. Furthermore, elevated DGM concentrations were observed in water that might have originated from river discharge. The gas-exchange of mercury between the ocean and the atmosphere was calculated in the open water and both deposition and evasion were observed. The measurements showed significantly enhanced DGM concentrations, compared to more southern latitudes.  相似文献   

Tectonic setting of post-orogenic granites within SW Fennoscandia based on deep seismic and gravity data     

M. Andersson  J. E. Lie  E. S. Husebye 《地学学报》1996,8(6):558-566

Within the Svecononvegian Province of SW Scandinavia granite intrusions are abundant. Prominent ones are the Bohus-Iddefjord and the Flå granites, the so- called Bohus-Flå Granite belt. The age of these granites, consistent at ≅ 900 Ma, coincides with the late extensional stage of the Svecononvegian-Grenvillian orogen. Gravity observations and deep seismic profiling lines are presented that also cover the Skagerrak Sea. The geophysical data suggest that the Bohus granite continues seaward for at least 80 km and its thickness, offshore, is estimated to be 2–4 km. Where the seismic profiling lines intersect the inferred seaward extension of the Bohus granite, a distinct reflection pattern is observed at ≅ 1.6 s. TWT. This coincides with a gravity modelled thickness of ≅ 4 km. The seismic profiles also show a large Moho offset beneath the modelled granite. It is proposed that this offset is related to Svecononvegian crustal underthrusting and that the granite melt could have formed by anatexis of mid-crustal rocks downthrusted to greater depths in the vicinity of the seismically observed Moho offset.  相似文献