Anthropic Exposure Indicator for River Basins Based on Landscape Characterization and Fuzzy Inference     

Elfany Reis do Nascimento Lopes  Carlos de Souza  José  Paixão de Sousa  Jocy Ana  Filho  José Luiz Albuquerque  Lourenço  Roberto Wagner 《Water Resources》2021,48(1):29-40

Water Resources - The objective of this study is to develop an anthropic exposure indicator for river basins using quantitative and qualitative aspects of the landscape and morphometric analysis...  相似文献   

Effects of mechanical macrophyte control on suspended sediment concentrations in streams     

MJC Greer  AS Hicks  SK Crow  GP Closs 《新西兰海洋与淡水研究杂志》2013,47(2):254-278

Suspended sediment (SS) is an important pollutant in freshwater ecosystems and can be detrimental to fish communities. Although macrophytes mediate sediment deposition, little effort has been put into determining how their removal affects sediment resuspension. The present study examined the immediate and long-term impacts of mechanical macrophyte removal on SS concentrations in streams. The results of this study suggest that bed disturbance during mechanical excavation of macrophytes significantly increases SS in the short term, and concentrations were found to increase by as much as 15,687 mg L^–1 immediately after macrophyte removal. Significant long-term (77 day) increases in SS were also observed, indicating that without macrophytes, disturbed material is continually resuspended after excavation by fluvial processes. These results demonstrate that macrophyte removal can result in SS levels that have previously been shown to harm fish, and indicate that this activity may be more detrimental to fish than previously thought.  相似文献   

Reproductive traits of Euterpina acutifrons in a coastal area of Southeastern Brazil     

Mauro de Melo Júnior  Leonardo K. Miyashita  Naira J. Silva  Salvador A. Gaeta  Rubens M. Lopes 《Marine Ecology》2013,34(3):363-372

We investigated the reproductive biology of the planktonic harpacticoid copepod Euterpina acutifrons, including morphometric data, egg production rates (EPR) and viability, and weight‐specific egg production. Experiments were carried out during 1 year in an inner‐shelf area off Ubatuba (SE Brazil), a site seasonally influenced by bottom intrusions of the relatively cold and nutrient‐rich South Atlantic Central Water (SACW). We hypothesized that E. acutifrons attain higher reproductive rates when SACW penetrates in this region. Live females were incubated individually in cell culture plates during two periods of 24 h each, under controlled temperature and light conditions. Euterpina acutifrons carried on average 16.9 ± 6.9 eggs·sac^?1, ranging between 10.8 ± 5.7 and 30.8 ± 7.4 eggs·sac^?1. Estimated EPRs ranged from 6.3 ± 3.4 to 13.6 ± 4.2 eggs·female^?1·day^?1, with mean weight‐specific egg production rates of 0.06 ± 0.04 and 0.17 ± 0.08 per day. Euterpina acutifrons was not directly influenced by SACW intrusions, but body length and clutch size were positively related to temperature and chlorophyll content. Egg hatching time was clearly dependent on water temperature, as a 2 °C increase resulted in a decrease of 15 h in egg hatching time. This shows that even a small variation in temperature may considerably affect E. acutifrons population dynamics. Reproductive traits of this pelagic harpacticoid seem, therefore, to be controlled by the trade‐offs between increased food supply and the metabolic demands at low temperatures associated with SACW bottom intrusions toward this coastal area.  相似文献   

Solar Variability Induced in a Dynamo Code by Realistic Meridional Circulation Variations     

I. Lopes  D. Passos 《Solar physics》2009,257(1):1-12

In this work we use an already-published method to infer a variation profile for the solar meridional circulation over the last 250 years. We feed this variation profile into a numerical dynamo code, and we reconstruct a sunspot time series that acts as a proxy for solar cycle activity. We perform three simulations with slightly different parameters, and the results are compared with the observational data. The medium and large correlation coefficients between reconstructed and observational time series seem to indicate that variations in meridional circulation play an important role in the modulation of solar activity.  相似文献   

The implications of experimental uncertainties in Newton's Constant on the standard evolution of the Sun     

IlÍ dio Lopes 《Astrophysics and Space Science》2003,283(4):553-558

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Metropolitan deconcentration, socio-political fragmentation and extended suburbanisation: Brazilian urbanisation in the 1980s and 1990s     

Marcelo Lopes de Souza 《Geoforum》2001,32(4)

The aim of this paper is to discuss the phenomena of socio-political fragmentation of urban space, extended suburbanisation and metropolitan deconcentration, which have been important features of Brazilian urbanisation since the 1980s (metropolitan deconcentration partly since the 1970s). At the beginning it profiles the recent evolution of the country's economy, in order to make sense of the worsening situation in terms of exclusion and violence in big Brazilian cities since the 1980s. Against this background, recent trends both in terms of socio-spatial segregation and social conflict within cities (formation of enclaves dominated by drug trafficking organisations and self-segregation of the élites as a response to this) and in terms of the growing attractiveness of areas outside the biggest metropolises (extended suburbanisation and metropolitan deconcentration) are analysed. The main focus is the socio-political dimension of Brazilian urbanisation in the 1980s and 1990s, which has been undervalued by analysts.  相似文献   

An overview of SAX99: acoustic measurements   总被引：5，自引：0，他引：5  

Thorsos  E.I. Williams  K.L. Chotiros  N.P. Christoff  J.T. Commander  K.W. Greenlaw  C.F. Holliday  D.V. Jackson  D.R. Lopes  J.L. McGehee  D.E. Piper  J.E. Richardson  M.D. Dajun Tang 《Oceanic Engineering, IEEE Journal of》2001,26(1):4-25

A high-frequency acoustic experiment was performed at a site 2 km from shore on the Florida Panhandle near Fort Walton Beach in water of 18-19 m depth. The goal of the experiment was, for high-frequency acoustic fields (mostly In the 10-300-kHz range), to quantify backscattering from the seafloor sediment, penetration into the sediment, and propagation within the sediment. In addition, spheres and other objects were used to gather data on acoustic detection of buried objects. The high-frequency acoustic interaction with the medium sand sediment was investigated at grazing angles both above and below the critical angle of about 30°. Detailed characterizations of the upper seafloor physical properties were made to aid in quantifying the acoustic interaction with the seafloor. Biological processes within the seabed and the water column were also investigated with the goal of understanding their impact on acoustic properties. This paper summarizes the topics that motivated the experiment, outlines the scope of the measurements done, and presents preliminary acoustics results  相似文献   

The water quality of the Ria de Aveiro lagoon, Portugal: from the observations to the implementation of a numerical model   总被引：1，自引：0，他引：1  

Lopes JF  Dias JM  Cardoso AC  Silva CI 《Marine environmental research》2005,60(5):594-628

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Metal concentrations, fluxes, inventories and chronologies in sediments from Sepetiba and Ribeira Bays: A comparative study     

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   

Early Warning Systems: Feasibility and End-Users' Point of View     

C. S. Oliveira  F. Mota de Sá  M. Lopes  M. A. Ferreira  I. Pais 《Pure and Applied Geophysics》2015,172(9):2353-2370

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