Frontal dynamics boost primary production in the summer stratified Mediterranean sea   总被引：1，自引：1，他引：0  

Antonio Olita  Arthur Capet  Mariona Claret  Amala Mahadevan  Pierre Marie Poulain  Alberto Ribotti  Simón Ruiz  Joaquín Tintoré  Antonio Tovar-Sánchez  Ananda Pascual 《Ocean Dynamics》2017,67(6):767-782

Bio-physical glider measurements from a unique process-oriented experiment in the Eastern Alboran Sea (AlborEx) allowed us to observe the distribution of the deep chlorophyll maximum (DCM) across an intense density front, with a resolution (～ 400 m) suitable for investigating sub-mesoscale dynamics. This front, at the interface between Atlantic and Mediterranean waters, had a sharp density gradient (Δρ ～ 1 kg/m³ in ～ 10 km) and showed imprints of (sub-)mesoscale phenomena on tracer distributions. Specifically, the chlorophyll-a concentration within the DCM showed a disrupted pattern along isopycnal surfaces, with patches bearing a relationship to the stratification (buoyancy frequency) at depths between 30 and 60 m. In order to estimate the primary production (PP) rate within the chlorophyll patches observed at the sub-surface, we applied the Morel and Andrè (J Geophys Res 96:685–698 1991) bio-optical model using the photosynthetic active radiation (PAR) from Argo profiles collected simultaneously with glider data. The highest production was located concurrently with domed isopycnals on the fresh side of the front, suggestive that (sub-)mesoscale upwelling is carrying phytoplankton patches from less to more illuminated levels, with a contemporaneous delivering of nutrients. Integrated estimations of PP (1.3 g C m^?2d^?1) along the glider path are two to four times larger than the estimations obtained from satellite-based algorithms, i.e., derived from the 8-day composite fields extracted over the glider trip path. Despite the differences in spatial and temporal sampling between instruments, the differences in PP estimations are mainly due to the inability of the satellite to measure DCM patches responsible for the high production. The deepest (depth > 60 m) chlorophyll patches are almost unproductive and probably transported passively (subducted) from upper productive layers. Finally, the relationship between primary production and oxygen is also investigated. The logarithm of the primary production in the DCM interior (chlorophyll (Chl) > 0.5 mg/m³) shows a linear negative relationship with the apparent oxygen utilization, confirming that high chlorophyll patches are productive. The slope of this relationship is different for Atlantic, mixed interface waters and Mediterranean waters, suggesting the presence of differences in planktonic communities (whether physiological, population, or community level should be object of further investigation) on the different sides of the front. In addition, the ratio of optical backscatter to Chl is high within the intermediate (mixed) waters, which is suggestive of large phytoplankton cells, and lower within the core of the Atlantic and Mediterranean waters. These observations highlight the relevance of fronts in triggering primary production at DCM level and shaping the characteristic patchiness of the pelagic domain. This gains further relevance considering the inadequacy of optical satellite sensors to observe DCM concentrations at such fine scales.  相似文献   

Paired 10Be sampling of polished bedrock and erratic boulders to improve dating of glacial landforms: an example from the Western Alps     

Charlotte Prud'homme  Riccardo Vassallo  Christian Crouzet  Julien Carcaillet  Jean-Louis Mugnier  Joaquin Cortés-Aranda 《地球表面变化过程与地形》2020,45(5):1168-1180

Cosmogenic nuclide dating of glacial landforms may lead to ambiguous results for ice retreat histories. The persistence of significant cosmogenic concentrations inherited from previous exposure may increase the apparent exposure ages for polished bedrocks affected by limited erosion under ice and for erratic boulders transported by glaciers and previously exposed in high-altitude rock walls. In contrast, transient burying by moraines, sediments and snow decreases the apparent exposure age. We propose a new sampling strategy, applied to four sites distributed in the Arc and Arve valleys in the Western Alps, to better constrain the factors that can bias exposure ages associated with glacial processes. We used the terrestrial cosmogenic nuclide ¹⁰Be (TCN) to estimate the exposure time from paired sampling of depth profiles in polished bedrock and on overlying erratic boulders. For a given sampling site, the exposure ages for both the polished bedrock and boulder are expected to be the same. However, in six cases out of seven, boulders had significantly higher ¹⁰Be surface concentrations than those of the associated polished surfaces. In present and past glacial processes, the ¹⁰Be distribution with depth for boulders and bedrocks implies the presence of an inheritance concentration of ¹⁰Be. Our study suggests that ¹⁰Be concentrations in erratic boulders and in polished bedrocks provide maximum and minimum exposure ages of the glacial retreat, respectively. © 2019 The Authors. Earth Surface Processes and Landforms published by John Wiley & Sons Ltd  相似文献   

Constraining Holocene sea levels using U‐Th ages of phreatic overgrowths on speleothems from coastal caves in Mallorca (Western Mediterranean)     

Paola Tuccimei  Michele Soligo  Joaquin Ginés  Angel Ginés  Joan Fornós  Jan Kramers  Igor Maria Villa 《地球表面变化过程与地形》2010,35(7):782-790

Phreatic overgrowths on speleothems (POS) are carbonate formations deposited at the water table of caves in unique karstic coastal settings having morphologies that can be directly related to sea level at the time of formation. The U‐Th ages of calcite and aragonite overgrowths collected from the modern water table in coastal caves on Mallorca (Cova de Cala Varques A and Cova des Pas de Vallgornera) were determined using high‐precision MC‐ICPMS techniques. U‐Th ages indicate that phreatic carbonate deposition occurred between ca 2·8 and at least 0·6 ka BP and are in accord with an archeologically estimated age of 3·7–3·0 ka BP for a drowned prehistoric construction at a depth of 1 m below current sea level in a cave from the same area. Speleothem δ¹³C and δ¹⁸O and chemical composition of cave pools provide supportive evidence that POS reflect mixing between seawater and brackish water table. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

Reply to “Comments on Nd−Sr isotopic compositions of lower crustal xenoliths-Evidence for the origin of mid-Tertiary felsic volcanics in Mexico” by K.L. Cameron and J.V. Robinson     

Joaquin Ruiz  P. Jonathan Patchett  Richard J. Arculus 《Contributions to Mineralogy and Petrology》1990,104(5):615-618

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MAJOR AND TRACE ELEMENT DETERMINATIONS ON NIST GLASS STANDARD REFERENCE MATERIALS 611, 612, 614 AND 1834 BY INDUCTIVELY COUPLED PLASMA-MASS SPECTROMETRY   总被引：1，自引：0，他引：1  

Kurt HOLLOCHER  Joaquin RUIZ 《Geostandards and Geoanalytical Research》1995,19(1):27-34

We report on the major and trace element composition and homogeneity of NIST (National Institute of Standards and Technology) glass standard reference materials 611, 612, 614, and 1834 for use as microanalytical trace element standards in laser ablation-inductively coupled plasma-mass spectrometry. The four analyzed NIST glasses were not designed as microanalytical standards, but their availability and careful preparation made them obvious candidates. Our data indicate that NIST 1834 is inhomogeneous on a scale of 100 mg with respect to several trace elements. Within analytical uncertainty, NIST 611, 612, and 614 are apparently homogeneous.  相似文献   

TRACE ELEMENT DETERMINATIONS FOR USGS BASALT BHVO-1 AND NIST STANDARD REFERENCE MATERIALS 278, 688 AND 694 BY INDUCTIVELY COUPLED PLASMA-MASS SPECTROMETRY     

Kurt HOLLOCHER  Ahmed FAKHRY  Joaquin RUIZ 《Geostandards and Geoanalytical Research》1995,19(1):35-40

Results are presented for 26 to 30 trace elements determined in four rock reference materials of geochemical interest: USGS Basalt BHVO-1, Rhyolite Obsidian NIST 278, Basalt NIST688, and Phosphate Rock NIST694. Determinations were made by inductively coupled plasma mass spectrometry (ICP-MS). Good agreement was obtained among solution standard comparison and standard addition analytical techniques, and among samples prepared with different dissolution methods. Generally good agreement was obtained between determined trace element values and values reported in the literature.  相似文献   

Measurement of copper release rates from antifouling paint under laboratory and in situ conditions: implications for loading estimation to marine water bodies     

Valkirs AO  Seligman PF  Haslbeck E  Caso JS 《Marine pollution bulletin》2003,46(6):763-779

The release of biocides, such as copper (Cu), from antifouling (AF) coatings on vessel hulls represents a significant proportion of overall Cu loading in those harbors and estuaries where substantial numbers of small craft or large vessels are berthed. Copper release rates were measured on several self-polishing, tin-free coatings and an ablative Cu reference coating applied to steel panels using three measurement methods. The panels were exposed in natural seawater in San Diego Bay, and release rates were measured both in the laboratory and field over 2 years. Results with the static (20 cm x 30 cm) panels indicated that Cu release rates were initially high (25-65 microg Cu cm(-2)day(-1)), with a large range of values between paint types. Release rates declined to substantially lower rates (8-22 microg cm(-2)day(-1)) with reduced variability within 2 months. Release rates continued to decrease over time for approximately 6 months when relatively constant release rates were observed for most coatings. Over time, relative differences in Cu release rates measured by three exposure methods decreased, with all coatings exhibiting similar behavior toward the end of the study. Lowest overall Cu release rates were observed with the self-polishing experimental paint no. 7 in static-dynamic and in situ treatments. The highest periodic release rates were measured from panels that experienced periods of both static and dynamic exposure (8.7 ms(-1) rotation). The lowest release rates were measured from panels that experienced static, constant depth exposure, and where release rates were evaluated in situ, using a novel diver-deployed measurement system. Results from this in situ technique suggests that it more closely reflects actual Cu release rates on vessel hulls measured with intact natural biofilms under ambient conditions than measurements using standardized laboratory release rate methods. In situ measurements made directly on the AF surface of vessels demonstrated typically lower release rates than from the panel studies, averaging 8.2 microg cm(-2)day(-1) on pleasure craft, and 3.8 microg cm(-2)day(-1) on Navy vessels. The data suggest that the presence of an established biofilm likely serves to moderate the release of Cu from field-exposed antifouling coatings both on panels and hull surfaces.  相似文献   

Cu isotopic fractionation in the supergene environment with and without bacteria   总被引：5，自引：0，他引：5  

Ryan Mathur  Joaquin Ruiz  Laura Liermann  Susan Brantley 《Geochimica et cosmochimica acta》2005,69(22):5233-5246

The isotopic composition of dissolved Cu and solid Cu-rich minerals [δ⁶⁵Cu (‰) = (⁶⁵Cu/⁶³Cu_sample/⁶⁵Cu/⁶³Cu_std) - 1)*1000] were monitored in batch oxidative dissolution experiments with and without Thiobacillus ferrooxidans. Aqueous copper in leach fluids released during abiotic oxidation of both chalcocite and chalcopyrite was isotopically heavier (δ⁶⁵Cu = 5.34‰ and δ⁶⁵Cu = 1.90‰, respectively, [±0.16 at 2σ]) than the initial starting material (δ⁶⁵Cu = 2.60 ± 0.16‰ and δ⁶⁵Cu = 0.58 ± 0.16‰, respectively). Isotopic mass balance between the starting material, aqueous copper, and secondary minerals precipitated in these experiments explains the heavier isotopic values of aqueous copper. In contrast, aqueous copper from leached chalcocite and chalcopyrite inoculated with Thiobacillus ferrooxidans was isotopically similar to the starting material. The lack of fractionation of the aqueous copper in the biotic experiments can best be explained by assuming a sink for isotopically heavy copper present in the bacteria cells with δ⁶⁵Cu = 5.59 ± 0.16‰. Consistent with this inference, amorphous Cu-Fe oxide minerals are observed surrounding cell membranes of Thiobacillus grown in the presence of dissolved Cu and Fe.Extrapolating these experiments to natural supergene environments implies that release of isotopically heavy aqueous Cu from oxidative leach caps, especially under abiotic conditions, should result in precipitates in underlying enrichment blankets that are isotopically heavy. Where iron-oxidizing cells are involved, isotopically heavy oxidized Cu entrained in cellular material may become associated with leach caps, causing the released aqueous Cu to be less isotopically enriched in the heavy isotope than predicted for the abiotic system. Rayleigh fractionation trends with fractionation factors calculated from our experiments for both biotic and abiotic conditions are consistent with large numbers of individual abiotic or biotic leaching events, explaining the supergene chalcocites in the Morenci and Silver Bell porphyry copper deposits.  相似文献   

Nd-Sr isotope composition of lower crustal xenoliths — Evidence for the origin of mid-tertiary felsic volcanics in Mexico     

Joaquin Ruiz  P. Jonathan Patchett  Richard J. Arculus 《Contributions to Mineralogy and Petrology》1988,99(1):36-43

Isotopic data were collected on lower crustal xenoliths to constrain the Mexican lower crust as source material for the mid-Tertiary Sierra Madre Occidental, which is one of the largest silicic volcanic piles known. The xenoliths are predominantly pelitic gneisses and mafic orthogneisses that were brought to the surface on the eastern edge of the Sierra Madre Occidental by recent alkalic basalts. The pelitic gneisses are uniform in mineral assemblage and contain garnet+quartz+plagioclase+sanidine+rutile +sillimanite/kyanite+graphite. The orthogneisses are plagioclase, garnet and/or spinel bearing two pyroxene granulites. Available geothermometric and geobarometric data show that the xenoliths equilibrated at temperatures and pressures consistent with those of the mantle/crust boundary in those areas.The xenoliths range from 46.2 to 67.2 SiO₂. Paragneisses are in general more silicic than the orthogneisses. The xenoliths have Rb concentrations between 0.4 and 97 ppm but most samples are very low, with less than 3 ppm Rb. The Sr isotopic ratios of orthogneisses from the lowermost crust throughout most of northern Mexico are very similar and range from ca. 0.705 to 0.706. Previous studies indicate that these rocks have measured (inNd) values between+2 and –5. Paragneiss xenoliths are generally more radiogenic in Sr isotopic ratio, up to 0.730, and have lower _Nd values of–11.The Nd and Sr isotopic characteristics of the orthogneisses are similar to those of the voluminous mid-Tertiary ignimbrites of the Sierra Madre Occidental. The xenoliths cannot represent cumulate material produced during the mid-Tertiary volcanism because they are Paleozoic or older. Consequently, based on Sr and Nd isotopic data, the silicic ignimbrites could comprise up to 100% lower crustal material.  相似文献   

A Location Aware Mobile Tool for Direct and Indirect Climate Data Sensors     

Francisco Ramos  Aida Monfort  Joaquin Huerta 《Transactions in GIS》2014,18(3):385-400

Access to GIS data from mobile platforms continues to be a challenge and there is a wide range of fields where it is extremely useful. In this work, we combined three key aspects: climate data sensors, mobile platforms and spatial proximity operations. We published and made use of a web 2.0 network of climate data, where content is user‐collected, by means of their meteorological stations, and exposed as available information for the virtual community. Moreover, we enriched this data by giving the users the opportunity to directly inform the system with different climate measures. In general, management of this type of information from a mobile application could result in an important decision tool, as it enables us to provide climate‐related data according to a context and a geographical location. Therefore, we implemented a native mobile application for iPhone and iPad platforms by using ArcGIS SDK for iOS and by integrating a series of ArcGIS webmaps, which allows us to perform geospatial queries based on the user's location, offering, at the same time, access to all the data provided by the climate data sensor network and from direct users.  相似文献