Predicting the optical properties of the West Florida Shelf: resolving the potential impacts of a terrestrial boundary condition on the distribution of colored dissolved and particulate matter   总被引：1，自引：0，他引：1  

W. Paul Bissett  Robert Arnone  Sharon DeBra  Dwight A. Dieterle  Daniel Dye  Gary J. Kirkpatrick  Oscar M. Schofield  Gabriel A. Vargo 《Marine Chemistry》2005,95(3-4):199-233

Predicting the distribution of Inherent Optical Properties (IOPs) in the water column requires predicting the physical, chemical, biological, and optical interactions in a common framework that facilitates feedback responses. This work focuses on the development of ecological and optical interaction equations embedded in a 2D hindcast model of the shallow water optical properties on the West Florida Shelf (WFS) during late summer/fall of 1998. This 2D simulation of the WFS includes one case with a Loop Current intrusion above the 40-m isobath and one with the Loop Current intrusion in addition to a periodic terrestrial nutrient supply below the 10-m isobath. The ecological and optical interaction equations are an expansion of a previously developed model for open ocean conditions (Bissett, W.P., Carder, K.L., Walsh, J.J., Dieterle, D.A., 1999a. Carbon cycling in the upper waters of the Sargasso Sea: II. Numerical simulation of apparent and inherent optical properties. Deep-Sea Research, Part I: Oceanographic Research Papers, 46 (2), 271–317; Bissett, W.P., Walsh, J.J., Dieterle, D.A., Carder, K.L., 1999b. Carbon cycling in the upperwaters of the Sargasso Sea: I. Numerical simulation of differential carbon and nitrogen fluxes. Deep-Sea Research, Part I: Oceanographic Research Papers, 46 (2), 205–269). The expansion includes an increase in the number of elemental pools to include silica, phosphorus, and iron, an increase in the number of phytoplankton functional groups, and a redevelopment of the Dissolved Organic Matter (DOM) and Colored Dissolved Organic Matter (CDOM) interaction equations. It was determined from this simulation that while the Loop Current alone was able to predict the water column conditions present during the summer, the Loop Current alone was not enough to simulate the magnitude of optical constituents present in the fall of 1998 when compared to satellite imagery. Simulating terrestrial inorganic and organic nutrients and CDOM pulses coinciding with significant meteorological events and high freshwater pulses released from the major rivers feeding the WFS were required to accurately predict the distribution and scale of the inherent optical properties at the surface during the fall months. Modeling the in situ light field for phytoplankton growth and community competition requires addressing the CDOM optical constituent explicitly. The majority of the annually modeled CDOM on WFS was created via in situ production; however, it was also rapidly removed via advection and photochemical destruction. A pulse of terrestrial nutrient and organic color was required to simulate the dramatic changes in surface color seen in satellite imagery on the WFS. The dynamics of the biogeochemical portion of the simulation demonstrate the importance of nonstoichiometric supplies of terrestrial nutrients on the WFS to the prediction of nutrient and CDOM fluxes.  相似文献   

Paleontology,sedimentology and paleoenvironment of a new fossiliferous locality of the Jurassic Cañadón Asfalto Formation,Chubut Province,Argentina     

Oscar F. Gallego  Nora G. Cabaleri  Claudia Armella  Wolfgang Volkheimer  Sara C. Ballent  Sergio Martínez  Mateo D. Monferran  Diego G. Silva Nieto  Manuel A. Páez 《Journal of South American Earth Sciences》2011,31(1):54-68

A new Late Jurassic assemblage of “conchostracans”, ostracods, bivalves and caddisfly cases from the locality “Estancia La Sin Rumbo”, Chubut Province (Patagonia, Argentina) is recorded. The fossils occur in the upper part of an outcropping 45 m thick volcaniclastic lacustrine sequence of yellowish tuffs and tuffites of the Puesto Almada Member, which is the upper member of the Cañadón Asfalto Formation with U/Pb age of 161 ± 3 Ma. The sequence represents one sedimentary cycle composed of a (lower) hemicycle of expansion and a (higher) hemicycle of contraction of the water body. The invertebrates lived in small freshwater bodies during the periods of expansion of the lake. The occurrence of a great number of small spinicaudatans, associated with mud-cracks, is evidence of dry climatic conditions and suggests several local mortality events. The spinicaudatan record of the fushunograptid–orthestheriid (component of the Eosestheriopsis dianzhongensis fauna) and the presence of Congestheriella rauhuti Gallego and Shen, suggest a Late Jurassic (Oxfordian to Tithonian) age. Caddisfly cases are recorded for the first time in the Cañadón Asfalto Basin.  相似文献   

Predicting seasonal ocean variability around New Zealand using a coupled ocean-atmosphere model     

Catherine O. de Burgh-Day  Claire M. Spillman  Craig Stevens  Oscar Alves  Graham Rickard 《新西兰海洋与淡水研究杂志》2019,53(2):201-221

We present a first assessment of the Sea Surface Temperature (SST) and 300m Heat Content (HC) ensemble mean skill of the Australian Community Climate and Earth-System Simulator-Seasonal v1.0 (ACCESS-S1) around New Zealand on seasonal timescales, using a set of retrospective ensemble forecasts for 1990-2012. This was verified against Reynolds AVHRR analysis and Bluelink ReANalysis 3.5 (BRAN3.5). For inshore areas with depth <300m, the model shows skill forecasting for summer at a lead time of 0 months, with 66% and 65% of model grid cells having correlation coefficients exceeding 0.6 for SST and 300m HC respectively. Regions of lower skill seem to be associated with the model representation of the complex and variable frontal systems around New Zealand, and an overly-strong response to the El Niño Southern-Oscillation (ENSO). Nevertheless, the skill of ACCESS-S1 around New Zealand suggests there is potential for the development of useful seasonal forecast products for the region.  相似文献   

Relationships between primary productivity and bottom‐water oxygenation off northwest Africa during the last deglaciation     

Helena L. Filipsson  Oscar E. Romero  Jan‐Berend W. Stuut  Barbara Donner 《第四纪科学杂志》2011,26(4):448-456

The upwelling region off northwest Africa is one of the most productive regions in the world ocean. This study details the response of surface‐ and deep‐water environments off Mauritania, northwest Africa, to the rapid climate events of the last deglaciation, especially the Bølling–Allerød (15.5–13.5 ka BP) and Younger Dryas (13.5–11.5 ka BP). A high accumulation rate gravity core GeoB7926‐2, recovered at ～20° N, 18° W, was analysed for the grain size distribution of the terrigenous sediment fraction, the organic carbon content, diatom and benthic foraminifera communities. Humid conditions were observed during the Bølling–Allerød with a high contribution of fluvial sediment input. During the Younger Dryas intensified trade winds caused a larger sediment input of aeolian dust from the Sahara and more intense upwelling with higher primary productivity, as indicated by high diatom concentrations. The abrupt and large increase of organic matter caused low oxygen conditions at the sea floor, reflected by the poor benthic foraminiferal fauna and the dominance of the low‐oxygen‐tolerant foraminiferal species Bulimina exilis. This is surprising since low‐oxygen conditions have not been recorded during modern times at the sea floor in this region, despite present‐day intensive upwelling and high primary productivity. After the Younger Dryas, more humid conditions returned, diatom abundance decreased and B. exilis was replaced by typical deep‐sea species as found in the region today, indicating the return of more oxygenated conditions at the sea floor. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

The Risk Atlas of Mexico City,Mexico: a tool for decision-making and disaster prevention     

Novelo-Casanova  David A.  Suárez  Gerardo  Cabral-Cano  Enrique  Fernández-Torres  Enrique A.  Fuentes-Mariles  Oscar A.  Havazli  Emre  Jaimes  Miguel Á.  López-Espinoza  Erika D.  Martin-Del Pozzo  Ana Lillian  Morales-Barrera  Wendy V.  Morales-Rodríguez  Hipólito L.  Nieto-Torres  Amiel  Rodríguez-Elizarrarás  Sergio R.  Solano-Rojas  Darío  Velasco-Herrera  Victor M. 《Natural Hazards》2022,111(1):411-437

Natural Hazards - We present a Risk Atlas of Mexico City based on a Geographical Information System (RA-GIS). We identified the prevalent social risk to the more relevant hazards in Mexico City...  相似文献   

Field accumulative behavior of organochlorine pesticides. The role of crabs and sediment characteristics in coastal environments     

Menone ML  Miglioranza KS  Botto F  Iribarne O  Aizpún de Moreno JE  Moreno VJ 《Marine pollution bulletin》2006,52(12):1717-1724

The influence of intertidal crab beds on the concentrations of organochlorine (OC) pesticides in sediment was studied in two different coastal environments in Argentina. Samples of male burrowing crabs (Chasmagnathus granulatus) were collected for this study. Our field data showed lower bioaccumulation of OC pesticides in crabs from sediments with a higher total organic carbon (TOC) and higher clay content. Thus, concentrations in crabs depend on the physico-chemical characteristics of the sediment where they live more than on the OC pesticide concentrations in the environment. The distribution patterns in sediment from inside and outside crab burrows were similar for both coastal areas being HCHs  γ-chlordane > p,p′-DDE for San Antonio Bay (SAO), and HCHs > p,p′-DDE  γ-chlordane for Mar Chiquita (MCh) coastal lagoon. OC pesticide concentrations in sediment were significantly lower inside than outside crab burrows, irrespective of the sediment physico-chemical characteristics due to the bioturbation activity of C. granulatus.  相似文献   

Study of the total lightning activity in a hailstorm   总被引：1，自引：0，他引：1  

Joan Montany  Serge Soula  Nicolau Pineda  Oscar van der Velde  Pere Clapers  Glria Sol  Joan Bech  D. Romero 《Atmospheric Research》2009,91(2-4):430-437

A thunderstorm that developed over northeastern Spain on 16 June 2006 is analyzed. This severe thunderstorm produced hailstones as large as 40 mm and had a lifetime of 3 h and 30 min. Radar cross-sections show strong vertical development with cloud echo tops reaching an altitude of 13 km. The specific characteristics of the lightning activity of this storm were: (i) a large amount (81%) of negative cloud-to-ground (−CG) flashes with very low peak currents (< 10 kA in absolute value), (ii) a very large proportion of intra-cloud (IC) flashes with an IC/CG ratio reaching about 400, (iii) a large number of “short” IC flashes (with only 1-VHF source according to SAFIR detection), (iv) a large increase of the −CG flash rate and of the CG proportion near the end of the storm. The rate of −CG flashes with a low peak current were observed to evolve similarly to the rates of IC flashes. Most of them have been assumed to be IC flashes misclassified by the Spanish Lightning Detection Network (SLDN). They have been filtered as it is usually done for misclassified +CG flashes. After this filtering, CG flash rates remained very low (< 1 min^− 1) with +CG flashes sometimes dominant. All the particular lightning activity characteristics similar to those observed in the Severe Thunderstorm Electrification and Precipitation Study (STEPS) campaigns support the hypothesis that this thunderstorm could have had an inverted-polarity or complex charge structure. The maximum IC flash rate (67 min^− 1) peaked 24 min before the presence of reflectivity higher than 60 dBZ. The IC activity abruptly decreased during the period when reflectivity was dramatically increasing. The time of maximum reflectivity observed by radar was consistent with the times of reported hail at the ground.  相似文献   

Influence of pore morphology on the durability of sedimentary building stones from Aragon (Spain) subjected to standard salt decay tests     

Oscar Buj  Josep Gisbert 《Environmental Earth Sciences》2010,61(7):1327-1336

The aim of the present article is to identify the influence of the pore morphology on the physical behaviour and durability of natural stone. Fifteen sedimentary rocks commonly used in the cultural and architectural heritage of Aragon (Spain) were characterized. The petrography, porous structure, fluid transport properties and durability of these rocks were analysed. They were classified into two different groups according to the results of the different tests. For each of these groups the physical behaviour was established. A principal components analysis was used in order to examine the correlation between pore structure, hydric properties and durability. The results show that the percentage of pore throats <0.1 μm control the fluid transport properties, have an important influence on stone durability, and can be used to predict resistance to salt decay while the average pore size does not. Stones with a high percentage of pore throats <0.1 μm are less susceptible to salt decay than stones with higher pore size if their pore network is characterized by high tortuosity and low connectivity.  相似文献   

The Southwest Atlantic intertidal burrowing crab Neohelice granulata modifies nutrient loads of phreatic waters entering coastal area     

Eugenia Fanjul  María A. Grela  Alejandro Canepuccia  Oscar Iribarne 《Estuarine, Coastal and Shelf Science》2008

Along the coastal areas of the Southwest Atlantic estuaries and embayments, phreatic water often circulates through very extended areas (up to several hundred meters perpendicular to the coast), dominated by dense assemblages of deep burrows of the crab Neohelice granulata (formerly Chasmagnathus granulatus). This crab inhabits the intertidal area, from mudflats to marshes vegetated by species of Spartina, Sarcocornia and Juncus, generating extensive burrowing beds where burrow density may reach up to 60 burrows m⁻². Since the lower limit of the crab burrows is usually the water table, we investigated through field experiments the effect of N. granulata and their burrows on the chemical characteristics of this phreatic water. Water analysis from experimental (1) occupied burrows (with crabs), (2) unoccupied burrows (where crabs were excluded), and (3) sediment pore water show remarkable differences. Water oxygenation, and nitrate, ammonium and sulphate concentrations inside occupied burrows were higher than in the water inside unoccupied burrows or pore waters. Moreover, directed sampling of phreatic water entering and leaving the crab bed, shows that dissolved inorganic nitrogen concentration is enhanced as the water crosses the crab bed. These results may be ascribed to the fact that in the salt marsh the crabs spend most of their time within burrows, where presumably they store food (plants) and defecate. These activities generate an area of accumulation of excrements and nutrients in different decomposition states. The present work shows a novel way by which bioturbating organisms can affect nutrients exportation from salt marshes to the open waters.  相似文献   

Oscillatoria rubescens D.C. as an Indicator of Lago Maggiore Eutrophication     

Prof. Oscar Ravera C.C.R.  Dr. R. A. Vollenweider 《Aquatic Sciences - Research Across Boundaries》1968,30(2):374-380

Zusammenfassung In der vorliegenden Arbeit wird das Auftreten vonOscillatoria rubescens D.C. im Lago Maggiore behandelt, welche Alge seit langem als biologischer Indikator für Trophiever?nderungen des Süsswassers gilt. Probenahmen an verschiedenen Stellen des Sees und aus bis 50 m Tiefe zeigen, dass die Art seit 10 Jahren betr?chtlich zugenommen hat, wobei im Herbst und Winter jeweils ein Maximum erreicht wird. Die Entwicklung vonOscillatoria rubescens D.C. weist auf eine Eutrophierung des Lago Maggiore durch h?usliche und industrielle Abw?sser hin.

---

Résumé Mise en évidence de l'envahissement du Lac Majeur (Lago Maggiore) parOscillatoria rubescens D.C., qui depuis longtemps est considérée comme un indicateur biologique du changement des conditions trophiques des eaux douces. Des collections en différents points du lac et jusqu'à une profondeur de 50 m montrent un accroissement considérable de cette espèce depuis 10 ans, avec un maximum en automne et en hiver. Le développement de cette algue prouve une eutrophisation du Lac Majeur due à des pollutions domestiques et industrielles.

---

---

This publication is contribution No. 395 of the Euratom Biology Division.  相似文献