Freshwater-saltwater interface and estuarine sediment in situ assays based on post-exposure feeding of chironomids and polychaetes     

Sara Soares  Susana Moreira  Sofia Andrade  Lúcia Guilhermino  Rui Ribeiro 《Estuaries and Coasts》2005,28(2):314-319

An integrated approach for ecological and ecotoxicological sediment assessments along the freshwater saltwater interface (FSI) and estuarine areas in general was developed, through the adaptation of recently proposed methods for the midge larvaChironomus riparius (an in situ assay based on post-exposure feeding for sediment toxicity assessments in freshwater systems) and the development of new techniques for the polychaeteHediste (Nereis) diversicolor (an in situ post-exposure feeding assay). Based on the previously proposed methods, improvements were made to the feeding quantification ofC. riparius fourth instar larvae. A method to quantify the post-exposure feeding ofH. diversicolor was developed and optimized under laboratory conditions using newly hatchedArtemia franciscana nauplii as a food source. Assay chambers and procedures fromC. riparius assays were easily adapted forH. diversicolor in situ exposures. Sediment assays using this integrated approach were successfully performed at an uncontaminated river-estuarine system. They consisted of a 48-h exposure followed by a 1-h post-exposure feeding for chironomids and a 2-h post-exposure feeding for polychaetes. Good recovery rates were obtained after the 48-h field exposure. Fluctuations in various physicochemical variables at the FSI, due to the tidal regime, did not significantly influenceC. riparius larval post-exposure feeding rates, suggesting that uncontaminated freshwater sites located upstream of FSI areas can be used as reference sites forC. riparius in situ evaluations in estuaries. Adapted assay chambers and procedures were suitable forH. diversicolor in situ exposures.  相似文献   

Fog precipitation on the Island of Madeira (Portugal)   总被引：2，自引：0，他引：2  

Susana Prada  Manuel da Silva 《Environmental Geology》2001,41(3-4):384-389

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Validation of a new endochronic liquefaction model for granular soil by using centrifuge test data   总被引：1，自引：0，他引：1  

Susana Lpez-Querol  Rafael Blzquez 《Soil Dynamics and Earthquake Engineering》2007,27(10):920-937

The application of a new liquefaction constitutive model, based on the endochronic theory applied to densification of sandy soil, to a set of centrifuge tests from the University of British Columbia, is presented in this paper. The model employed herein takes into account, in a unified formulation, contractive and dilative behaviours, and considers the soil collapse as well. First of all, the model is calibrated by means of undrained cyclic simple shear stress test data. The constitutive law of the soil is implemented in the bidimensional coupled finite element code CMLIQ (Cyclic Mobility and LIQuefaction), developed by the authors. Three centrifuge tests are analysed, the seismic loading and the geometry being the same for all of them, namely an improved slope with drain devices or denser soil at some locations. Comparisons between the data provided by the numerical model and the experimental measurements are shown, and, as a result, the accuracy of the model is explored and evaluated.  相似文献   

Characterizing proteases in an Antarctic Janthinobacterium sp. isolate：Evidence of a protease horizontal gene transfer event     

Cecilia Martinez-Rosales  Juan Jos Marizcurrena  Andrs Iriarte  Natalia Fullana  Hctor Musto  Susana Castro-Sowinski 《极地研究(英文版)》2015,(1)

We report the isolation of a cold-adapted bacterium belonging to the genus Janthinobacterium (named AU11), from a water sample collected in Lake Uruguay (King George Island, South Shetlands). AU11 (gro...  相似文献   

UAV navigation system using line-based sensor pose estimation     

Julien Li-Chee-Ming  Costas Armenakis 《地球空间信息科学学报》2018,21(1):2-11

Abstract

This work presents a mapping and tracking system based on images to enable a small Unmanned Aerial Vehicle (UAV) to accurately navigate in indoor and GPS-denied outdoor environments. A method is proposed to estimate the UAV’s pose (i.e., the 3D position and orientation of the camera sensor) in real-time using only the on-board RGB camera as the UAV travels through a known 3D environment (i.e., a 3D CAD model). Linear features are extracted and automatically matched between images collected by the UAV’s onboard RGB camera and the 3D object model. The matched lines from the 3D model serve as ground control to estimate the camera pose in real-time via line-based space resection. The results demonstrate that the proposed model-based pose estimation algorithm provides sub-meter positioning accuracies in both indoor and outdoor environments. It is also that shown the proposed method can provide sparse updates to correct the drift from complementary simultaneous localization and mapping (SLAM)-derived pose estimates.  相似文献   

Tidal variations of some physico-chemical parameters in Blanca Bay,Argentina     

Marta Susana Orozco Storni  Rubén José Lara  Adán Edgardo Pucci 《Estuarine, Coastal and Shelf Science》1984,19(4):485-491

Oxygen, alkalinity, nutrients, pH, temperature and salinity were measured through tidal cycles in two points of Blanca Bay. A clear dependence of nutrients, oxygen and alkalinity with salinity and tide conditions was observed in the inner point, being attenuated in the outer one.  相似文献   

Horse mackerel egg identification using DNA methodology     

Nikoletta Karaiskou  Alexander Triantafyllidis  Paula Alvarez  Placida Lopes  Eva Garcia-Vazquez  & Costas Triantaphyllidis 《Marine Ecology》2007,28(4):429-434

Egg identification in plankton samples is usually needed for purposes of stock assessment. Until recently, only morphological characters were used for identifying the eggs of different fish species. Late developmental stages are easily distinguishable due to pigmentation as well as egg and oil globule size range. However, for early stages, these characteristics are difficult to be discriminated and may overlap with other species. European horse mackerel species (Trachurus trachurus, T. mediterraneus, T. picturatus) overlap significantly in their spawning areas in some European waters. Because of the fact that their eggs are morphologically similar, genetic methodologies are needed to identify eggs and larvae to species correctly. In the present study, formalin‐ and ethanol‐preserved eggs were tested to estimate the efficacy of genetic methodologies for species identification of eggs when different preservatives are used. A 370‐bp fragment of cytochrome b was successfully amplified followed by restriction fragment analysis with two restriction enzymes aiming to identify the eggs to species. Horse mackerel egg identification was accomplished with the maximum success in ethanol‐preserved eggs. However, it seems that various preservatives had different effects on the DNA quality of eggs as genetic identification was less successful in formalin‐preserved eggs. Preserving in ethanol a part of the eggs obtained in plankton surveys is suggested for purposes of accurate genetic identification, even if their morphological features are distorted in time.  相似文献   

Water-soluble inorganic ions of size-differentiated atmospheric particles from a suburban site of Mexico City     

Telma Castro  Oscar Peralta  Dara Salcedo  José Santos  María I. Saavedra  María L. Espinoza  Alejandro Salcido  Ana-Teresa Celada-Murillo  Susana Carreón-Sierra  Harry Álvarez-Ospina  Giovanni Carabali  Valter Barrera  Sasha Madronich 《Journal of Atmospheric Chemistry》2018,75(2):155-169

During the MILAGRO campaign, March 2006, eight-stage cut impactors were used to sample atmospheric particles at Tecámac (T1 supersite), towards the northeast edge of the Mexico City Metropolitan Area, collecting fresh local emissions and aged pollutants produced in Mexico City. Particle samples were analyzed to determine total mass concentrations of Ca²⁺, Mg²⁺, NH₄ ⁺, K⁺, Cl^?, SO₄ ^2?, and NO₃ ^?. Average concentrations were 22.1 ± 7.2 μg m^?3 for PM₁₀ and 18.3 ± 6.2 μg m^?3 for PM_1.8. A good correlation between PM₁₀ and PM_1.8, without influence from wind patterns, indicates that local emissions are more important than the city’s pollution transported to the site, despite the fact that Tecámac is just 40 km away from Mexico City. A lack of diurnal patterns in the PM_2.5/PM_1.8 ratio supports this conclusion. The inorganic composition of particles suggests that vehicles, soil resuspension, and industries are the main pollutant sources. Finally, the particles were found to be neutralized, in agreement with observations in the Mexico City Metropolitan Area.  相似文献   

Interpopulation Differences in Salinity Tolerance of the Invasive Cordgrass Spartina densiflora: Implications for Invasion Process     

Enrique Mateos-Naranjo  Susana Redondo-Gómez 《Estuaries and Coasts》2016,39(1):98-107

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Detection of fluid mud layers using tuning fork,dual-frequency echo sounder,and chirp sub-bottom measurements     

Carneiro  Juliane Castro  Gallo  Marcos N.  Vinzón  Susana B. 《Ocean Dynamics》2020,70(4):573-590

Ocean Dynamics - Many ports and navigation channels around the world suffer from silting and the presence of fluid mud layers, which can cause reductions in nautical depth. In this context, the...  相似文献