Monitoring estuaries using non-permanent stations: practical aspects and data examples     

Erwan Garel  ��scar Ferreira 《Ocean Dynamics》2011,61(7):891-902

This paper deals with the performances of non-permanent environmental monitoring stations when recording at high-sampling interval (hour) over a long term (months, years) within estuarine waters. Information about data quality and system maintenance requirements are provided based on the experience gained with an autonomous station deployed during 2?years at the Guadiana Estuary (southern Portugal–Spain border). The station includes (1) a multi-parameter probe for water quality (temperature, conductivity, dissolved oxygen, turbidity, chlorophyll and pH) inserted in a tube through a surface-floating buoy; and, (2) a bottom-mounted current meter. The main issues for the continuous acquisition of valid data were biofouling on the optical (chlorophyll, turbidity, dissolved oxygen), conductivity sensors of the probe and high sediment dynamics at the bed. The definition of a detailed maintenance programme is required for the lengthening of (valid) data time series. The typical variability of the parameters is described at seasonal and tidal time scales and episodic events are identified (coastal upwelling and high freshwater inputs). These examples illustrate how integrated data analysis is fundamental to define and understand the changes induced by specific events on several interrelated parameters, and, more generally, how these systems can contribute to a better understanding of the hydro-ecological processes operating in estuaries.  相似文献   

Isotope geochemistry of Paleoproterozoic metacarbonates from Itatuba,Borborema Province,Northeastern Brazil: Evidence of marble melting within a collisional suture     

Roberto Ventura Santos  Edilton J. dos Santos  João Adauto de Souza Neto  Luis Christian Montreuil Carmona  Alcides Nóbrega Sial  Luis Henrique Mancini  Lauro Cézar Montefalco de Lira Santos  Gilzênia Henrique do Nascimento  Lucas UpaDafubigin Santos Mendes  Emerson Marcello Ferreira Anastácio 《Gondwana Research》2013,23(1):380-389

Strongly-deformed marbles may be easily confused with linear and elongated carbonatite intrusions. Both rocks may present similar texture and foliation to the host rock, or even cross cutting field relationships, which could be interpreted either as igneous or high-grade metamorphosed marble. Diagnostic criteria are even more complex when there is evidence of melting of the metasedimentary carbonate rock, such as has been described in the Himalayas and in the Eastern Ghats, India.In the Alto Moxotó Terrane, a high-grade gneissic domain of the Borborema Province, Northeastern Brazil, there are metacarbonates associated with banded gneisses and different metaplutonic rocks. Field evidence indicates the absence of other metasedimentary rocks associated with these marbles, thus suggesting that these carbonates were separated from other siliciclastic metasedimentary rocks. The presence of marble also suggests that it may represent the initial stage of a crustal carbon recycling into the mantle. These marbles present many field similarities to carbonatites (e.g., fluid-flow structure) and, together with metagranites and metamafic intrusions, may represent a major collisional tectonic suture.A detailed study of the carbon, oxygen and strontium isotopic composition of these marbles is presented. This study aims to identify the origin of the different isotopic components. It is argued that these rocks were subjected to temperature and pressure conditions that were sufficiently high to have melted them. The isotopic data presented here support this interpretation and indicate the mixing of two components: (i) one characterized by radiogenic Sr isotopes and mantle-like carbon isotopes, which is associated with the gneissic and mafic rocks, and (ii) another characterized by low ⁸⁷Sr/⁸⁶Sr ratios and highly positive δ¹³C values. Available geochemical data for the upper Paleoproterozoic indicate that the ⁸⁷Sr/⁸⁶Sr ratio of ocean water, varying between 0.7050 (2.25 ± 0.25 Ga) and 0.7047 (1.91 Ga), falls within the lower range of the samples from Itatuba and thus reinforces the interpretation that these marbles are sedimentary-derived and were partially contaminated by interaction with the host gneissic and mafic rocks.  相似文献   

Seasonal Diet Shifts and Overlap Between Two Sympatric Catfishes in an Estuarine Nursery     

David Valença Dantas  Mario Barletta  Jonas de Assis Almeida Ramos  André Ricardo Araújo Lima  Monica Ferreira da Costa 《Estuaries and Coasts》2013,36(2):237-256

This study describes the seasonal feeding habits of different size classes of Cathorops spixii and Cathorops agassizii along an estuarine ecocline and the food overlap when different size classes occur together. These species were essentially zoobenthivorous, feeding mainly on Polychaeta Nereis sp., Copepoda Pseudodiaptomus acutus, Ostracoda Asterope sp., Gastropoda: Littorinidae, and Bivalvia Mytilus sp. and Anomalocardia brasiliana. However, during their life cycle and between different habitats and seasons, their trophic guild can change to zooplanktivore. The competition for resources was observed among C. spixii and C. agassizii, but was significantly reduced due to the seasonal diference in habitat use by different ontogenetic phases in the main channel of the estuary. The food niche separation was strongly influenced by environmental fluctuations, principally of salinity, resulting from rainfall and river inflow. High abundance of some preys, such as P. acutus (all estuary), Asterope sp. (upper and middle estuary), and Littorinidae (upper and lower estuary), could influence the significant diet overlap, principally during the rainy season, and call for more detailed studies of the benthic community structure. Moreover, dietary overlap was observed mainly between smaller sizes (intraspecific and/or interspecific) or between corresponding ontogenetic phases (interspecific), suggesting some differentiation in the diet in relation to the size class. Differences in prey type and size between the different ontogenetic phases of these ariids, principally among juveniles and adults, could be related to the size of the mouth, since adults are able to successfully capture larger preys or larger quantities of particular items.  相似文献   

Overview of integrative tools and methods in assessing ecological integrity in estuarine and coastal systems worldwide   总被引：9，自引：1，他引：8  

Borja A  Bricker SB  Dauer DM  Demetriades NT  Ferreira JG  Forbes AT  Hutchings P  Jia X  Kenchington R  Carlos Marques J  Zhu C 《Marine pollution bulletin》2008,56(9):1519-1537

In recent years, several sets of legislation worldwide (Oceans Act in USA, Australia or Canada; Water Framework Directive or Marine Strategy in Europe, National Water Act in South Africa, etc.) have been developed in order to address ecological quality or integrity, within estuarine and coastal systems. Most such legislation seeks to define quality in an integrative way, by using several biological elements, together with physico-chemical and pollution elements. Such an approach allows assessment of ecological status at the ecosystem level ('ecosystem approach' or 'holistic approach' methodologies), rather than at species level (e.g. mussel biomonitoring or Mussel Watch) or just at chemical level (i.e. quality objectives) alone. Increasing attention has been paid to the development of tools for different physico-chemical or biological (phytoplankton, zooplankton, benthos, algae, phanerogams, fishes) elements of the ecosystems. However, few methodologies integrate all the elements into a single evaluation of a water body. The need for such integrative tools to assess ecosystem quality is very important, both from a scientific and stakeholder point of view. Politicians and managers need information from simple and pragmatic, but scientifically sound methodologies, in order to show to society the evolution of a zone (estuary, coastal area, etc.), taking into account human pressures or recovery processes. These approaches include: (i) multidisciplinarity, inherent in the teams involved in their implementation; (ii) integration of biotic and abiotic factors; (iii) accurate and validated methods in determining ecological integrity; and (iv) adequate indicators to follow the evolution of the monitored ecosystems. While some countries increasingly use the establishment of marine parks to conserve marine biodiversity and ecological integrity, there is awareness (e.g. in Australia) that conservation and management of marine ecosystems cannot be restricted to Marine Protected Areas but must include areas outside such reserves. This contribution reviews the current situation of integrative ecological assessment worldwide, by presenting several examples from each of the continents: Africa, Asia, Australia, Europe and North America.  相似文献   

Spatial distribution of sedimentary linear alkylbenzenes and faecal steroids of Santos Bay and adjoining continental shelf, SW Atlantic, Brazil: origin and fate of sewage contamination in the shallow coastal environment   总被引：1，自引：0，他引：1  

Martins CC  Ferreira JA  Taniguchi S  Mahiques MM  Bícego MC  Montone RC 《Marine pollution bulletin》2008,56(7):1359-1363

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Microhabitat use by endangered Iberian cyprinids nase Iberochondrostoma almacai and chub Squalius aradensis     

José M. Santos  Maria T. Ferreira 《Aquatic Sciences - Research Across Boundaries》2008,70(3):272-281

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Study of Metal Distribution in Raw and Screened Swine Manure   总被引：1，自引：0，他引：1  

Ricardo Luís Radis Steinmetz  Airton Kunz  Valderi Luiz Dressler  Érico Marlon de Moraes Flores  Ayrton Figueiredo Martins 《洁净——土壤、空气、水》2009,37(3):239-244

The growth of industrial swine production over the last few years has led to a growth in concern over effluents generated by the activity. Several elements, mainly toxic metals, can be present in swine wastewater and can have a serious environmental impact. It is important, therefore, to know the metal concentration before the discharge of wastewater. In this work the temporal metal distribution in swine manure and its potential reduction using coarse (2 mm) and fine (<0.45 μm) liquid‐solid separation techniques were investigated. In order to do this, different swine manure sample preparation methods for Al, Ba, Cd, Co, Cr, Cu, Fe, Mg, Mn, Ni, Pb, Sr and Zn determination by Inductively Coupled Plasma Optical Emission Spectrometry (ICP OES) were tested. The acid mixtures used to digest the manure sample significantly affected the metal recovery. Good analyte recoveries were observed with nitric acid/hydrogen peroxide mixtures or nitric acid/perchloric acid mixtures. Sulfuric acid/hydrogen peroxide mixtures produced inconsistent results and poor recoveries, mainly for Ba and Pb. It was observed that metal concentrations in swine manure varied greatly with time, up to one order of magnitude, due to changes in swine production such as feed and animal numbers. Metals concentrations observed in the raw wastewater exceeded Brazilian limits for discharge into water bodies and recommendations for agricultural use. Results obtained from the liquid‐solid separation study showed that metals in the raw swine manure were not removed with coarse screening. However, the major fraction of metals were removed by filtration (0.45 μm), with the exception of Na, K and Sr. Thus, the use of liquid‐solid separation techniques that capture the fine solid fractions (and associated metals) from raw manure can have a favorable impact on the environment and contribute to swine production wastewater treatment.  相似文献   

气象卫星云图的多分辨小波分解及人工神经网络降水估计研究   总被引：7，自引：0，他引：7  

李伟钢  石立华 《南京气象学院学报》2000,23(2)

采用多分辨小波分析对卫星图象进行预处理 ,在保留其特征信息的同时 ,减小了数据量 ,改善了神经网络训练过程的收敛性能 ,提高了处理速度。采用这一方法根据 GOES- 8的红外亮温图象和气象雷达资料对巴西圣保罗州中部的降水量估计进行了试验 ,取得了良好的效果。  相似文献   

Effect of a broad shallow sill on tidal circulation and salt transport in the entrance to a coastal plain estuary (Mira—Vila Nova de Milfontes, Portugal)     

J. O. Blanton  M. A. Ferreira  F. A. Andrade 《Estuaries and Coasts》2000,23(3):293-304

We describe the tidal circulation and salinity regime of a coastal plain estuary that connects to the ocean through a flood tide delta. The delta acts as a sill, and we examine the mechanisms through which the sill affects exchange of estuarine water with the ocean. Given enough buoyancy, the dynamics of tidal intrusion fronts across the sill and selective withdrawal (aspiration) in the deeper channel landward appear to control the exchange of seawater with estuarine water. Comparison of currents on the sill and stratification in the channel reveals aspiration depths smaller than channel depth during neap tide. During neap tide and strong vertical stratification, seawater plunges beneath the less dense estuarine water somewhere on the sill. Turbulence in the intruding bottom layer on the sill promotes entrainment of fluid from the surface layer, and the seawater along the sill bottom is diluted with estuarine water. During ebb flow, salt is effectively trapped landward of the sill in a stagnant zone between the aspiration depth and the bottom where it can be advected farther upstream by flood currents. During spring tide, the plunge point moves landward and off the sill, stratification is weakened in the deep channel, and aspiration during ebb extends to the bottom. This prevents the formation of stagnant water near the bottom, and the estuary is flooded with high salinity water far inland. The neapspring cycle of tidal intrusion fronts on flood coupled with aspiration during ebb interacts with the sill to play an important role in the transport and retention of salt within the estuary.  相似文献   

X-ray emission from nearby M-dwarfs: the super-saturation phenomenon     

David J. James  Moira M. Jardine  Robin D. Jeffries  Sofia Randich  rew Collier Cameron  Miguel Ferreira 《Monthly notices of the Royal Astronomical Society》2000,318(4):1217-1226

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