Controls on Quaternary coastal evolution of the east-northeastern coast of Brazil: roles of sea-level history, trade winds and climate     

JosMaria Landim Dominguez  Abilio Carlos da Silva Pinto Bittencourt  Louis Martin 《Sedimentary Geology》1992,80(3-4):213-232

East-northeastern Brazil has a wave-dominated, micro- to meso-tidal coast, lying entirely within the southern Atlantic trade wind belt. Integration of geologic mapping, radiocarbon dating and vibracoring data shows that the Quaternary coastal evolution of this area was controlled by three major factors: (1) sea-level history; (2) trade winds; and (3) climate change.

Sea-level history. Along the east-northeastern coast of Brazil, relative sea level has fallen approximately 5 m during the last 5000 y. Correlation of this sea-level history with the evolution of beach-ridge, lagoonal and coastal plain deposits shows that: (1) sea-level rise favours the formation of barrier island—lagoonal systems and the construction of intralagoonal deltas; (2) sea-level lowering is not conductive to barrier island formation. Rather, lagoons and bays become emergent and beach-ridge plains rapidly prograde.

Trade winds. Sediment dispersal systems along the coastal zone of east-northeastern Brazil have been highly persistent since Pleistocene time, as deduced from beach-ridge orientation. This persistence results from the fact that sediment dispersal in wave-dominated settings is ultimately controlled by atmospheric circulation which, for the east-northeastern coast of Brazil is associated with the South Atlantic high-pressure cell. The remarkable stability of this cell through time, has allowed the accumulation of extensive beach-ridge plains at the longshore drift sinks located along the coast.

Climate change. Effects of Quaternary climate changes on coastal sedimentation are twofold. Climate changes may affect rainfall patterns, thus exerting an important control on coastal dune development. Along the coast of northeastern Brazil, active coastal dunes are only present in those areas in which at least four consecutive dry months occur during the year. Mapping of these areas has shown that dune development during the Holocene has been episodic, these episodes being probably controlled by variations in rainfall patterns associated with climate changes. Secondly, despite its overall stability, the position of the high-pressure cell has experienced small shifts in position during the Holocene in response to climate changes. Changes in wind direction associated with these shifts have induced modifications in the coastal dispersion system, which are recorded in the strandplains as small truncations in the beach-ridge alignments.

These results have important implications in understanding accumulation of ancient sandstone shoreline sequences.  相似文献   

A paleoenvironmental reconstruction of Laguna Babícora, Chihuahua, Mexico based on ostracode paleoecology and trace element shell chemistry     

Manuel R. Palacios-Fest  Ana Luisa Carreño  José R. Ortega-Ramírez  Guillermo Alvarado-Valdéz 《Journal of Paleolimnology》2002,27(2):185-206

Paleoecology of Laguna Babícora, Chihuahua, Mexico was reconstructed using ostracode faunal assemblages and shell chemistry. The paleolimnological record is used to show the magnitude of paleoclimatic changes in the area from 25,000 years to the present.Faunal assemblages consist of four species of the genus Limnocythere: L. sappaensis, L. ceriotuberosa, L. bradburyi and L. platyforma, all associated with Candona caudata, Candona patzcuaro and Cypridopsis vidua. A paleosalinity index developed from these assemblages indicates that the lake's salinity fluctuated frequently from oligo- to meso-haline conditions during the last 25,000 years. This pattern and low salinity range are in good agreement with modern TDS (here used as an indicator of salinity) values recorded from 26 wells and one spring from the area (258–975 mg l^–1). To estimate paleotemperature we examined the trace element content (Mg/Ca ratios) from individual valves of L. ceriotuberosa and L. platyforma, the two species most commonly recorded in Laguna Babícora.Shell Mg/Ca ratios of 204 specimens of these two species were used to estimate water temperature (Mg/Ca) by means of experimental standard coefficients. Our data show that paleowater temperature ranged from 5.6–21.3 °C (with 2 values ranging from 0.2–4.8 °C), which suggest a close correlation with atmospheric temperatures around the lake. These results are in good agreement with a modern mean winter temperature (3.5 °C) and mean summer temperature (20 °C) recorded in the area between 1970 and 1980.  相似文献   

Shell‐shape and morphometric variability in Mytilus galloprovincialis from micro‐tidal environments: responses to different hydrodynamic drivers          下载免费PDF全文

Vanessa Moschino  Monica Bressan  Luigi Cavaleri  Luisa Da Ros 《Marine Ecology》2015,36(4):1440-1453

Tidal conditions differently influence inter‐tidal organisms in terms of general physiological and metabolic responses. In this study we investigated the morphological response in shells of Mytilus galloprovincialis native to different micro‐tidal coastal environments in the Northern Adriatic Sea. Our purpose was to highlight the ecophenotypic variability across tidal levels and to elucidate how tidal currents and waves produced by anthropogenic activities may play a part in modulating shell morphology. Three sampling sites were selected: an open‐sea area 15 km off‐shore and two sites within the lagoon of Venice, the first near one of its three inlets, and the other one in the proximity of Venice city centre. At each sampling site, organisms were seasonally collected at different depths within their vertical zonation, either in the inter‐tidal zone – i.e. at both the highest and lowest tide zonation limits, and subtidally. The mussel shells were analysed by investigation of their morphometric relationships (height/length and width/length ratios) and by elliptic Fourier analysis of the shell contours. Shell thickness and condition index were also evaluated for a better comprehension of energy allocation/partitioning. Estimates based on long‐term measurements, visual observation, wind statistics and wave growth laws allowed an evaluation of the forces acting on shells. At the open‐sea site, the observed phenotypic variability of both shell shape and thickness was clearly related to the tidal vertical zonation. At the two lagoon sites, the currents generated by tidal flow through the inlet and the waves caused by the frequent passage of boats influenced both shell shape and thickness. A trade‐off between protection and growth was apparent along the tide gradient, as emphasized by the differences in the partitioning and allocation of energy between shell and flesh production.  相似文献   

Sequence stratigraphic framework of a mixed turbidite-contourite depositional system along the NW slope of the South China Sea   总被引：1，自引：0，他引：1  

Luisa Palamenghi  Hanno Keil  Volkhard Spiess 《Geo-Marine Letters》2015,35(1):1-21

  相似文献   

The Response of Estuarine Macrobenthic Communities to Natural- and Human-Induced Changes: Dynamics and Ecological Quality     

João Magalhães Neto  Heliana Teixeira  Joana Patrício  Alexandra Baeta  Helena Veríssimo  Rute Pinto  João Carlos Marques 《Estuaries and Coasts》2010,33(6):1327-1339

Anthropogenic activities are a disturbance factor of coastal systems and can be widely recognized as a major threat to the health of coastal systems. However, natural events cannot be disregarded from management issues because of their significant influence on the communities living in these areas. Based on long-term subtidal data from the Mondego Estuary (Portugal), the effects of natural events (e.g., floods and droughts) on macrobenthic communities were compared with the anthropogenic events. Sampling stations were grouped into characteristic zones (mouth, north arm, south arm) so the community dynamics of each of these estuarine areas could be followed over time. Environmental assessment was performed for stations using the Benthic Assessment Tool (BAT), and compared with the existing pressures. Human impacts persist over a number of years and gradually reduce ecosystem health, as discussed in the European Water Framework Directive. Paradoxically, natural events cause stronger impacts but are of a shorter duration, which allows for a faster recovery of macrobenthic communities. The study showed that caution should be taken when developing and implementing water policies so as not to disregard the importance of the different events (natural and human-caused) on the ecosystem health (e.g., community degradation and water quality and ecological quality status assessment).  相似文献   

Mineralogical and geochemical spatial analyses of a waste-rock dump at the Libiola Fe–Cu sulphide mine (Eastern Liguria,Italy)     

Pietro Marescotti  Eva Azzali  Diego Servida  Cristina Carbone  Giovanni Grieco  Luisa De Capitani  Gabriella Lucchetti 《Environmental Earth Sciences》2010,61(1):187-199

In this work, we investigated a 3 ha sulphide-bearing waste-rock dump (Libiola Mine, Italy) using mineralogical, geochemical, and geostatistical analyses. The dumped materials were highly heterogeneous in grain size and lithology and varied both laterally and vertically. Other than the host rock of the ore, basalts and serpentinites, the dumped materials contained high amounts of low-grade chalcopyrite- and pyrite-rich mineralisations. Due to these characteristics and to the absence of minerals able to neutralise acidity, this waste-rock dump can be classified as an acid mine drainage (AMD) producer. The study confirms that AMD is still active and, in the best scenario, can persist for up to 6.17 × 10³ years. The consequences of this process are of serious environmental concern as it involves strong acidification of the circulating waters, the release of potentially toxic metals into the soil, streams and rivers and the precipitation of huge quantities of secondary Fe-oxides and Fe-oxyhydroxides.  相似文献   

Bioremediation of dry olive-mill residue removes inhibition of growth induced by this waste in tomato plants     

M. García-Sánchez  A. Paradiso  I. García-Romera  E. Aranda  M. C. de Pinto 《International Journal of Environmental Science and Technology》2014,11(1):21-32

The disposal of dry olive-mill residue, the waste product from olive oil production, is a serious environmental issue. Dry olive-mill residue, being rich in organic and inorganic nutrients, could be used as fertilizer; however, it contains phenolic compounds that can inhibit plant growth. In order to clarify whether bioremediation of this waste could be a valuable strategy for its reuse, the effect of aqueous extract of dry olive-mill residue, untreated or bioremediated by the saprobe fungi Coriolopsis rigida and Penicillium chrysogenum-10, has been analyzed in relation to some physiological parameters of tomato plants. The data show that aqueous dry olive-mill residue significantly reduces the biomass of roots and shoots. In particular, it causes a dramatic reduction in root length, area, and volume as well as in the number of root tips. At an early stage, aqueous dry olive-mill residue also reduces the content of chlorophyll a and b and the efficiency of PS II. The inhibition of growth seems to be due to the increase in phenolic compounds that induce oxidative stress. Interestingly, when plants are treated with aqueous dry olive-mill residue bioremediated by saprobe fungi a decrease in phenolic content and an alleviation of oxidative stress occur. In conclusion, the results show that bioremediation of aqueous dry olive-mill residue is a useful tool to remove most of the inhibiting effects of this waste on plant growth.  相似文献   

Modeling heavy metal concentration distributions in estuarine waters: an application to Suances Estuary (Northern Spain)     

María Luisa Sámano  Andrés García  José Antonio Revilla  César Álvarez 《Environmental Earth Sciences》2014,72(8):2931-2945

  相似文献   

Distribution of dissolved labile and particulate iron and copper in Terra Nova Bay polynya (Ross Sea,Antarctica) surface waters in relation to nutrients and phytoplankton growth     

Paola Rivaro  Carmela Ianni  Serena Massolo  M. Luisa Abelmoschi  Cinzia De Vittor  Roberto Frache 《Continental Shelf Research》2011,31(7-8):879-889

The distribution of the dissolved labile and of the particulate Fe and Cu together with dissolved oxygen, nutrients, chlorophyll a and total particulate matter was investigated in the surface waters of Terra Nova Bay polynya in mid-January 2003. The measurements were conducted within the framework of the Italian Climatic Long-term Interactions of the Mass balance in Antarctica (CLIMA) Project activities. The labile dissolved fraction was operationally defined by employing the chelating resin Chelex-100, which retains free and loosely bound trace metal species. The dissolved labile Fe ranges from below the detection limit (0.15 nM) to 3.71 nM, while the dissolved labile Cu from below the detection limit (0.10 nM) to 0.90 nM. The lowest concentrations for both metals were observed at 20 m depth (the shallowest depth for which metals were measured). The concentration of the particulate Fe was about 5 times higher than the dissolved Fe concentration, ranging from 0.56 to 24.83 nM with an average of 6.45 nM. The concentration of the particulate Cu ranged from 0.01 to 0.71 nM with an average of 0.17 nM. The values are in agreement with the previous data collected in the same area. We evaluated the role of the Fe and Cu as biolimiting metals. The N:dissolved labile Fe ratios (18,900–130,666) would or would not allow a complete nitrate removal, on the basis of the N:Fe requirement ratios that we calculated considering the N:P and the C:P ratios estimated for diatoms. This finding partially agrees with the Si:N ratio that we found (2.29). Moreover we considered a possible influence of the dissolved labile Cu on the Fe uptake process.  相似文献   

Jurassic‐to‐present thermal history of the central High Atlas (Morocco) assessed by low‐temperature thermochronology     

Luis Barbero  Antonio Teixell  María‐Luisa Arboleya  Pedro del Río  Peter W. Reiners  Blaid Bougadir 《地学学报》2007,19(1):58-64

Apatite fission track (AFT) and (U–Th)/He data from the High Atlas have been obtained for the first time to constrain the tectono‐thermal evolution of the central part of the chain. Results from Palaeozoic basement massifs indicate long residence at low temperatures, consistently with their original location out of the deepest Mesozoic rift troughs and indicating minor exhumation. The best rocks for extracting the Alpine history of the Atlas Mountains are Jurassic intrusives, which yield AFT ages centred on c. 80 Ma; thermal models based on AFT data and constrained by (U–Th)/He suggest that these ages are included in a slow cooling trend from intrusion age to c. 50 Ma ago that we attribute to post‐rift thermal relaxation. This is followed by a stability period of c. 30 Ma and then by a final exhumational cooling until present exposure. Eocene intrusives yield AFT ages similar to those of Rb–Sr and K–Ar suggesting rapid emplacement in the uppermost crust.  相似文献