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441.
Novoa S Chust G Sagarminaga Y Revilla M Borja A Franco J 《Marine pollution bulletin》2012,64(4):739-750
The implementation of water quality European Directives requires an intensification of water quality monitoring, within the limits of the Exclusive Economic Zone. Remote sensing technologies can provide a valuable tool for frequent, synoptic, water-quality observations, over large areas. The aim of this study is to assess the ecological status of Basque coastal water bodies using satellite imagery from MODIS sensor, together with optical and chlorophyll-ain situ measurements. Thus, sea surface satellite-derived chl-a algorithms, the OC3 M, OC5 and a Local empirical algorithm, were compared against in situ measurements using satellite in situ match-ups, 90th Percentile (P90) monthly values for the 2005-2010 period. The OC5 algorithm corresponded most accurately with in situ measurements performed in the area, hence, it was selected. A P90 chlorophyll-a map was created with this algorithm to apply the classification scheme required by the directives. The classification of water bodies, based upon satellite-derived chlorophyll-a, could improve considerably the assessment of water quality. 相似文献
442.
Copper speciation in continental inputs to the Vigo Ria: sewage discharges versus river fluxes 总被引:1,自引:0,他引:1
Continental inputs of copper via rivers and sewage into the Vigo Ria were evaluated. The main fluvial input is not contaminated and the most degraded discharges occur on the southern margin of the middle ria. Continental inputs of copper and ligands to the ria are dominated by sewage treatment plants (136 mol Cu day(-1), 124 mol L day(-1)) supported by rivers (15 mol Cu day(-1), 21 mol L day(-1)). The dissolved fraction is the main channel of discharge for rivers (66%) with particulate matter being predominant in sewage (63%). Dissolved copper is organically complexed both in rivers (99.8%) and sewage (99.9%). This minor difference may be attributed to the fact that the stability of sewage complexes is greater than those in rivers. Moreover, ligand concentrations are higher in sewage than in rivers. Thus, the natural continental inputs of copper and ligands into the ria are magnified by anthropogenic inputs (5-15 and 3-5 times higher for copper and ligands, respectively). 相似文献
443.
Patricia Bernrdez Ricardo Prego Manuel Varela Guillermo Francs 《Continental Shelf Research》2008,28(17):2496-2508
Modern diatom distribution patterns in the surface sediment of the Ferrol Ría and their relationship to the hydrography and diatom patterns in the water column were studied to determine the hydrographic influence on the record of these biogenic components. Diatom abundance in the water column was assessed for different oceanographic periods and compared with the biosiliceous sedimentary record. Very low abundances were found in the water column during the winter, whereas in spring and summer, diatoms proliferated. Chaetoceros spp. formed the bulk of the water column community during spring and summer, followed by Thalassionema nitzschioides and Rhizosolenia spp. Nitzschia longissima represented a significant portion of the winter assemblage, together with Paralia sulcata and benthic taxa. Leptocylindrus danicus, N. longissima and Skeletonema costatum characterized the autumn campaign, when stratification of the waters occurs, with L. danicus being especially abundant in the outer ría.Seasonal hydrographic and associated productivity patterns govern the abundance and assemblage of the diatoms preserved in surface sediments. Samples located in the inner ría area and its margins exhibited the highest abundances of diatoms, and were primarily dominated by benthic species. The freshwater group, crysophycean cysts and phytoliths were present in the landward stations influenced by river runoff. The middle ría was characterized by P. sulcata and Thalassiosira spp., with minor occurrences of the benthic and freshwater group. Chaetoceros R.S., L. danicus R.S. and T. nitzschioides typified the outer ría, an assemblage that corresponds to nutrient-rich coastal areas of high productivity influenced by oceanic waters, demonstrating the impact of oceanic waters flowing into the embayment due to enhanced tidal mixing through the narrow channel. Therefore, sediment diatom assemblages reflect diatom production patterns in the water column of the Ría. However, we must proceed with caution when interpreting the paleorecord in the inner area due to the high contribution of allochthonous taxa, which is indicative of low water depths. This paper contributes to a better understanding of diatom thanatocoenosis in the Galician Rías, where very few studies of this kind have been done to date. 相似文献
444.
Benamar Ahmed Correia dos Santos Ricardo N. Bennabi Abdelkrim Karoui Tarek 《Acta Geotechnica》2019,14(3):815-823
Acta Geotechnica - An experimental study on internal erosion of coarse-grained soils collected from the Rhine River is presented. The tests performed on laboratory column aim to assess the... 相似文献
445.
Franciane de Carvalho Gomes Jos Marcus Godoy Maria Luiza D.P. Godoy Zenildo Lara de Carvalho Ricardo Tadeu Lopes Joan Albert Sanchez-Cabeza Luiz Drude de Lacerda Julio Cesar Wasserman 《Marine pollution bulletin》2009,59(4-7):123
Three sediment cores were sampled at Sepetiba Bay and four cores at Ribeira Bay, Rio de Janeiro State, Brazil. Sediment accumulation rates and chronologies were obtained from 210Pb activity-depth profiles. Sediment accumulation rates in Ribera Bay ranged from 1.2 mm y−1 in the inner bay to 2.6 mm y−1 close to its entrance. In Sepetiba Bay two sediment accumulation rates were observed: a lower rate of 0.35 cm y−1 before the 1960s and 0.76 cm y−1 since then. The cause of this change is due to the construction of the Santa Cecília impoundment (1955) that brings water from the Paraíba do Sul Basin into the Guandu River, which increased its flow from the original 20 m3 s−1 to 160 m3 s−1. Concentration of 44 elements was obtained by ICP-MS after total dissolution of samples from two selected cores. The relative differences between the concentrations of crustal elements, such as Al, Fe and Ti are only about 20% (p < 0.05). Cd and Zn are 15 and four times larger in Sepetiba Bay than in Ribeira Bay, respectively. Other major and minor elements show lower statistically significant differences. The enrichment factors and metal inventories show that Sepetiba Bay can be considered polluted with Bi, Cd, Cr, Cu, Sb and Zn. Particularly, Cd and Zn present concentrations three and four times higher than the Brazilian existing limits. 相似文献
446.
Luigina Vezzoli Massimo Matteini Natalia Hauser Ricardo Omarini Roberto Mazzuoli Valerio Acocella 《Bulletin of Volcanology》2009,71(5):509-532
The Middle-Upper Miocene Las Burras–Almagro-El Toro (BAT) igneous complex within the Eastern Cordillera of the central Andes
(∼24°S; NW Argentina) has revealed evidence of non-explosive interaction of andesitic magma with water or wet clastic sediments
in a continental setting, including peperite generation. We describe and interpret lithofacies and emplacement mechanisms
in three case studies. The Las Cuevas member (11.8 Ma) comprises facies related to: (i) andesite extruded in a subaqueous
setting and generating lobe-hyaloclastite lava; and (ii) marginal parts of subaerial andesite lava dome(s) in contact with
surface water, comprising fluidal lava lobes, hyaloclastite, and juvenile clasts with glassy rims. The Lampazar member (7.8 Ma)
is represented by a syn-volcanic andesite intrusion and related peperite that formed within unconsolidated, water-saturated,
coarse-grained volcaniclastic conglomerate and breccia. The andesite intrusion is finger-shaped and grades into intrusive
pillows. Pillows are up to 2 m wide, tightly packed near the intrusion fingers, and gradually become dispersed in the host
sediment ≥50 m from the parent intrusion. The Almagro A member (7.2 Ma) shows evidence of mingling between water-saturated,
coarse-grained, volcaniclastic alluvial breccia and intruding andesite magma. The resulting intrusive pillows are characterized
by ellipsoidal and tubular shape and concentric structure. The high-level penetration of magma in this coarse sediment was
unconfined and irregular. Magma was detached in apophyses and lobes with sharp contacts and fluidal shapes, and without quench
fragmentation and formation of a hyaloclastite envelope. The presence of peperite and magma–water contact facies in the BAT
volcanic sequence indicates the possible availability of water in the system between 11–7 Ma and suggests a depositional setting
in this part of the foreland basin of the central Andes characterized by an overall topographically low coastal floodplain
that included extensive wetlands. 相似文献
447.
Ricardo A. Olea Vera Pawlowsky-Glahn 《Stochastic Environmental Research and Risk Assessment (SERRA)》2009,23(6):749-757
The Kolmogorov–Smirnov test is a convenient method for investigating whether two underlying univariate probability distributions
can be regarded as undistinguishable from each other or whether an underlying probability distribution differs from a hypothesized
distribution. Application of the test requires that the sample be unbiased and the outcomes be independent and identically
distributed, conditions that are violated in several degrees by spatially continuous attributes, such as topographical elevation.
A generalized form of the bootstrap method is used here for the purpose of modeling the distribution of the statistic D of the Kolmogorov–Smirnov test. The innovation is in the resampling, which in the traditional formulation of bootstrap is
done by drawing from the empirical sample with replacement presuming independence. The generalization consists of preparing
resamplings with the same spatial correlation as the empirical sample. This is accomplished by reading the value of unconditional
stochastic realizations at the sampling locations, realizations that are generated by simulated annealing. The new approach
was tested by two empirical samples taken from an exhaustive sample closely following a lognormal distribution. One sample
was a regular, unbiased sample while the other one was a clustered, preferential sample that had to be preprocessed. Our results
show that the p-value for the spatially correlated case is always larger that the p-value of the statistic in the absence of spatial correlation, which is in agreement with the fact that the information content
of an uncorrelated sample is larger than the one for a spatially correlated sample of the same size. 相似文献
448.
Caroline Petus Guillem Chust Francis Gohin David Doxaran Jean-Marie Froidefond Yolanda Sagarminaga 《Continental Shelf Research》2010
The Basque coastal waters (South Bay of Biscay) are directly influenced by the Adour River freshwater plume. The Adour outflow leads to important variations of suspended matter concentrations and turbidity, which in turn may affect biological productivity and water quality. This study aims at both developing specific algorithms and testing the efficiency of atmospherically corrected MODIS-Aqua 250-m surface reflectance product (MYD09) to map total suspended matter concentrations and turbidity within the Adour coastal region. First, regional empirical algorithms based on in-situ data were tested to retrieve the concentration of total suspended matter and turbidity from the remote sensing reflectance. Then, the respective sensitivity of MODIS surface reflectance bands 1 and 2 for water quality application was investigated as well as the quality of atmospheric corrections. Finally, selected algorithms were applied to the MYD09 product. The resulting 250-m resolution maps were then compared to 1000-m maps produced by IFREMER and comparisons between satellite measurements and in-situ sampling points were performed. Results show that MODIS-Aqua band 1 (620–670 nm) is appropriate for predicting turbidity and total suspended matter concentrations using polynomial regression models, whilst band 2 is unadapted. Comparison between total suspended matter concentration 250-m resolution maps and mineral suspended matter 1000-m maps (generated by IFREMER) produced consistent results. A high correlation was obtained between turbidity measured in-situ and turbidity retrieved from MODIS-Aqua satellite data. 相似文献
449.
A Methodology for the Assessment of Unconventional (Continuous) Resources with an Application to the Greater Natural Buttes Gas Field,Utah 总被引:1,自引:0,他引:1
The Greater Natural Buttes tight natural gas field is an unconventional (continuous) accumulation in the Uinta Basin, Utah,
that began production in the early 1950s from the Upper Cretaceous Mesaverde Group. Three years later, production was extended
to the Eocene Wasatch Formation. With the exclusion of 1100 non-productive (“dry”) wells, we estimate that the final recovery
from the 2500 producing wells existing in 2007 will be about 1.7 trillion standard cubic feet (TSCF) (48.2 billion cubic meters
(BCM)). The use of estimated ultimate recovery (EUR) per well is common in assessments of unconventional resources, and it
is one of the main sources of information to forecast undiscovered resources. Each calculated recovery value has an associated
drainage area that generally varies from well to well and that can be mathematically subdivided into elemental subareas of
constant size and shape called cells. Recovery per 5-acre cells at Greater Natural Buttes shows spatial correlation; hence,
statistical approaches that ignore this correlation when inferring EUR values for untested cells do not take full advantage
of all the information contained in the data. More critically, resulting models do not match the style of spatial EUR fluctuations
observed in nature. This study takes a new approach by applying spatial statistics to model geographical variation of cell
EUR taking into account spatial correlation and the influence of fractures. We applied sequential indicator simulation to
model non-productive cells, while spatial mapping of cell EUR was obtained by applying sequential Gaussian simulation to provide
multiple versions of reality (realizations) having equal chances of being the correct model. For each realization, summation
of EUR in cells not drained by the existing wells allowed preparation of a stochastic prediction of undiscovered resources,
which range between 2.6 and 3.4 TSCF (73.6 and 96.3 BCM) with a mean of 2.9 TSCF (82.1 BCM) for Greater Natural Buttes. A
second approach illustrates the application of multiple-point simulation to assess a hypothetical frontier area for which
there is no production information but which is regarded as being similar to Greater Natural Buttes. 相似文献
450.
D. L. Jauncey S. Levin L. Teitelbaum M. Hofstadter J. Arballo S. McConnell R. Dorcey K. Cole N. Kreuser-Jenkins J. Leflang E. Kruzins L. Ricardo S. Horiuchi G. Nagle C. G. Miro 《Astronomy Reports》2017,61(4):281-287
This paper describes a radio astronomy programfor schools, the Goldstone-AppleValley Radio Telescope,GAVRT. The GAVRT program is designed to bring the inspiration and enthusiasm to a younger generation of teachers and children who learn about science by doing real science, just as Iosif Shklovsky brought to an older generation. 相似文献