CPLat: first operational experimental processing center for SIRGAS in Argentina     

María Paula Natali  M. Müller  L. Fernández  C. Brunini 《Journal of Geodesy》2009,83(3-4):219-226

The SIRGAS permanent GPS network which is in fact the IGS network densification for the American continent, consists today of more than 200 stations covering the continent and islands. It is currently processed by the IGS RNAAC SIR centre at Deutsches Geodätisches Forschungsinstitut producing weekly free solutions relying on IGS final orbits and EOP that contribute to the ITRF through IGS. By August 2006, the SIRGAS Working Group I had accepted five proposals for experimental processing centers within the region that would collaborate with IGS RNAAC SIR. One of them, Centro de Procesamiento La Plata (CPLat) in Argentina, began processing 60 stations on October 2006. By January 2007 CPLat reached operational capability, delivering weekly free solution SINEX files, with an internal consistency of 1.5 mm average for the horizontal components, and 3 mm in the vertical. Comparisons with IGS global and IGS RNAAC SIR weekly solutions were taken as external consistency indications, showing average RMS residuals of 1.8, 2.4 and 5 mm for the north, east, and vertical component, respectively. Analysis and comparison of adjusted solution time series from CPLat and other processing centers has proved to be highly valuable for solution QC, namely detection and identification of station anomalous behavior or modelling problems. These procedures will ensure the maintenance of the performance specifications for CPLat solutions. Action is being taken in order to guarantee the continuity of this effort beyond the experimental phase.  相似文献   

Composition,abundance, distribution and seasonality of larval fishes in the shallow nearshore of the proposed Greater Addo Marine Reserve,Algoa Bay,South Africa     

Paula Pattrick  Nadine A. Strydom 《Estuarine, Coastal and Shelf Science》2008

The larval fish assemblage was investigated in the shallow, nearshore region of a proposed marine protected area in eastern Algoa Bay, temperate South Africa, prior to proclamation. Sampling was conducted at six sites along two different depth contours at ∼5 m and ∼15 m to assess shore association. Larvae were collected by means of stepped oblique bongo net tows deployed off a ski-boat, twice per season for 2 years between 2005 and 2007. In total, 6045 larval fishes were collected representing 32 families and 78 species. The Gobiidae, Cynoglossidae, Clupeidae, Engraulidae and Sparidae were the dominant fish families. Catches varied significantly among seasons peaking in spring with a mean of ∼200 larvae/100 m³. Mean overall larval density was higher along the deeper contour, at ∼15 m (40 larvae/100 m³). The preflexion stage of development dominated catches at the ∼5 m (80%) and ∼15 m (73%) depth contours. Body lengths of Argyrosomus thorpei, Caffrogobius gilchristi, Diplodus capensis, Heteromycteris capensis and Solea turbynei, all estuary associated species, were larger at the shallow sites nearer to shore. Larvae of coastal species that produce benthic eggs dominated catches (75%) in the shallow sites (∼5 m) but were less abundant (32%) farther from shore at the deeper (∼15 m) sites. All developmental stages of D. capensis, Engraulis capensis, H. capensis, Sardinops sagax and two Pomadasys species were found in the study area. It appears that some species use the shallow nearshore as a nursery area.  相似文献   

Geochemical mobility of arsenic in the surficial waters from Argentina     

Alicia Daniela Robles  Paula Polizzi  María Belén Romero  Leila Natalia Chiodi Boudet  Sandra Medici  Agustín Costas  Marcela Gerpe 《Environmental Earth Sciences》2016,75(23):1479

The presence of arsenic (As) in surface water constitutes an important environmental risk, where mobility and adsorption processes are responsible for its behavior in the sediment–water interface. Therefore, the assessment of adsorption, mobility and water availability of arsenic in freshwater sediments, with agricultural, livestock and urban soil uses was performed. Arsenic concentrations in sediments ranged from 5.4 to 15.9 mg kg^?1 (total) and 2.8 to 6.5 mg kg^?1 (labile), and those of iron and manganese were 11,563–23,500 and 140.6–662.1 mg kg^?1, respectively. The As levels in water were significantly lower than those of sediments. Results would suggest that As co-precipitation and adsorption on Fe oxides are probably the major route of immobilization, determining its low lability. Manganese did not present an outstanding contribution to the retention, and cation-exchange capacity, pH and organic matter of sediments did not show an influence on the mobility of As.  相似文献   

Über das Vorkommen des Aluminiums in einer ooidische Eisenerze enthaltenden marinen Schichtfolge     

Paula Schneiderhöhn 《Contributions to Mineralogy and Petrology》1964,10(2):141-151

Ohne Zusammenfassung Herrn Prof. Dr.Carl W. Correns zum 70. Geburtstag gewidmet.  相似文献   

Population structure of Merluccius merluccius along the Iberian Peninsula coast     

Castillo  Ana G.F.; Alvarez  Paula; Garcia-Vazquez  Eva 《ICES Journal of Marine Science》2005,62(8):1699-1704

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Testing the accuracy of synthetic stellar libraries     

Lucimara P. Martins  Paula Coelho 《Monthly notices of the Royal Astronomical Society》2007,381(4):1329-1346

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Cave bear occupation in Schwabenreith Cave,Austria, during the early last glacial: constraints from 230Th/U‐dated speleothems     

Christoph Sptl  Denis Scholz  Gernot Rabeder  Paula J. Reimer 《第四纪科学杂志》2019,34(6):424-432

The cave bear was a prominent member of the Upper Pleistocene fauna in Eurasia. While breakthroughs were recently achieved with respect to its phylogeny using ancient DNA techniques, it is still challenging to date cave bear fossils beyond the radiocarbon age range. Without an accurate and precise chronological framework, however, key questions regarding the palaeoecology cannot be addressed, such as the extent to which large climate swings during the last glacial affected the habitat and possibly even conditioned the final extinction of this mammal. Key to constraining the age of cave bear fossils older than the lower limit of radiocarbon dating is to date interlayered speleothems using ²³⁰Th/U. Here we report new results from one such site in the Eastern European Alps (Schwabenreith Cave), which yielded the highest density of bones of cave bear (Ursus spelaeus eremus). Although dating of the flowstones overlying this fossiliferous succession was partly compromised by diagenetic alteration, the ²³⁰Th/U dates indicate that the bear hibernated in this cave after about 113 ka and before about 109 ka. This time interval coincides with the equivalent of Greenland Stadial 25, suggesting possible climate control on the cave bear's habitat and behaviour. © 2019 The Authors. Journal of Quaternary Science Published by John Wiley & Sons Ltd  相似文献   

A grain-size correction for metal pollution indexes in river sediments     

Thomas Vincent Gloaguen  Paula Núbia Soares Dalto Motta  Carolina Fonseca Couto 《国际泥沙研究》2021,36(3):362-372

According to the List of Hazardous Substances of the Agency of the Toxic Substances and Disease Registry(ATSDR 2017),some metallic elements such as Pb or Cd are still considered as the most polluting elements in the world.These elements accumulate in sediments,and there are various methods available that differentiate lithogenic sources from anthropogenic sources.For that,the natural geochemical background is required,however,its definition is far from unanimous:it can be a global or local value,single or statistically estimated value,depending on the studies.Our study is focused on the Suba
e River in the state of Bahia,Northeastern Brazil,which was historically contaminated by lead metallurgy.The river sediments were sampled at 21 locations:one at the discharge point of the plant's rainwater basin,ten upstream,and ten downstream.The total contents of Fe,Ti,Mn,Pb,Zn,Cu,Cr,particle-size distribution,and organic matter were analyzed.The conventional geochemical indexes,i.e.,the pollution degree(mCd),pollution load index,and enrichment factor indicated contamination by Zn,Pb,Cr,and Cu.Then,a new enrichment factor is introduced,assuming that the sediments come from erosion of soils in the watershed.After obtaining the natural concentrations of metals in the clay,silt,and sand fractions of uncontaminated reference soils,we corrected the pollution indexes by calculating a new individual background in each sediment sample,according to its grain size distribution.This new approach provided more precise indexes in the assessment of sediment pollution,by highlighting higher contamination of Zn and Pb(around 50%)and at the same time the absence of Cr and Cu contamination,two metals not involved with the metallurgical activity.  相似文献   

Collisional evolution of Trans-Neptunian populations: Effects of fragmentation physics and estimates of the abundances of gravitational aggregates     

Paula G. Benavidez 《Planetary and Space Science》2009,57(2):201-215

The Trans-Neptunian region is yet another example of a collisional system of small bodies in the Solar System. In the last decade the number of TNOs with reliable orbital elements is steadily increasing and even if it is still premature to compare models with observations, we can start to have some idea of the orbital structure and magnitude distribution, so that some loose constraints may be set on the critical parameters that affect collisional evolution. With this aim we have developed a model for the collisional evolution of the Trans-Neptunian region by dividing it into three main different populations, corresponding to the dynamical classification proposed by Gladman et al. [2001.The structure of the Kuiper Belt: size distribution and radial extent. Astrophys. J. 122, 1051] (Resonant region, Classical Belt and Scattered Disk). A multi-zone collisional model is developed, in which each zone can collisionally interact with each other. The model takes into account the known physics of the fragmentation of icy/rocky bodies at the typical relative velocities of TNOs, according to velocity distributions corresponding to each evolving zone. The dependence of the evolution of the considered populations on physically critical collisional parameters is investigated and the corresponding results are presented, including estimates of the abundance of gravitational aggregates in the studied populations.  相似文献   

Magnetotelluric measurements at Eusebio,an equatorial station     

N.B. Trivedi  Elesbão G. de Souza  Eurico R. de Paula  J.M. da Costa  Hugo Fournier 《Physics of the Earth and Planetary Interiors》1981,25(3):241-244

Magnetotelluric measurements in the period range 100–86400 s were conducted at a coastal station under the equatorial electrojet (Eusebio, 3.87°S, 321.58°E). The magnetotelluric data were hand-scaled and analysed to obtain a scalar apparent resistivity profile at Eusebio. The depth of the intermediate conducting layer was found to be in the range 45–75 km and the final conducting layer seems to begin at a depth of about 350 km. Possible effects of the source field equatorial electrojet are discussed and our results are compared with those of an African station under the equatorial electrojet.  相似文献