Niencheski L.F.H.,Institute Oceanografia FURG
Portugaliae Electrochimica Acta | Year: 2011
Sediments can sink or deliver elements to water column. Iron is considered an essential element for the development of cyanobacteria and a limitant to phytoplankton growth. Studies on the chemical speciation of iron in seawater have been conducted, but there is no information about its chemical speciation in pore water, as reported here. This paper presents a voltammetric method to analyze dissolved iron and its chemical speciation in sediment pore water, using adsorptive cathodic stripping voltammetry (AdCSV) and the technique of competitive ligand exchange (CLE-AdCSV), respectively. The limit of detection (LOD = 0.30 10 -6 mol L -1), the quantification (LOQ = 0.90×10 -6 mol L -1), precision (RSD = 4.9%) and accuracy (98%), were calculated from experiments using certified reference material SLRS-4 (National Research Council Canada). The chemical speciation of pore water from sediment samples collected during April 2009, in the Patos Lagoon Estuary (RS, Brazil), was analyzed for the first time, revealing that the ratio (labile iron to dissolved iron) is significantly lower in pore water extracted from sediments of the upper layer (0 to -5 cm), than from the overlaying water or of the pore water extracted from sediments of the lower layer (-15 to -20 cm).
Amaral A.C.Z.,University of Campinas |
Corte G.N.,University of Campinas |
Filho J.S.R.,Federal University of Pernambuco |
Denadai M.R.,University of Sao Paulo |
And 9 more authors.
Brazilian Journal of Oceanography | Year: 2016
Sandy beaches constitute a key ecosystem and provide socioeconomic goods and services, thereby playing an important role in the maintenance of human populations and in biodiversity conservation. Despite the ecological and social importance of these ecosytems, Brazilian sandy beaches are significantly impacted by human interference, chemical and organic pollution and tourism, as well as global climate change. These factors drive the need to better understand the environmental change and its consequences for biota. To promote the implementation of integrated studies to detect the effects of regional and global environmental change on beaches and on other benthic habitats of the Brazilian coast, Brazilian marine researchers have established The Coastal Benthic Habitats Monitoring Network (ReBentos). In order to provide input for sample planning by ReBentos, we have conducted an intensive review of the studies conducted on Brazilian beaches and summarized the current knowledge about this environment. In this paper, we present the results of this review and describe the physical, biological and socioeconomics features of Brazilian beaches. We have used these results, our personal experience and worldwide literature to identify research projects that should be prioritized in the assessment of regional and global change on Brazilian sandy beaches. We trust that this paper will provide insights for future studies and represent a significant step towards the conservation of Brazilian beaches and their biodiversity. © Universidade de Sao Paulo. All rights reserved.
Goncalves-Araujo R.,Institute Oceanografia Furg |
De Souza M.S.,Institute Oceanografia Furg |
Mendes C.R.B.,Institute Oceanografia Furg |
Mendes C.R.B.,University of Lisbon |
And 3 more authors.
Journal of Plankton Research | Year: 2012
This study investigates the relationships between the spring phytoplankton community and environmental factors in the Brazil-Malvinas confluence region. Phytoplankton community composition was determined by the high performance liquid chromatography/CHEMTAX approach, complemented with microscopic examination. Abiotic factors included temperature, salinity, dissolved inorganic macronutrients (ammonium, nitrite, nitrate, phosphate and silicate), water column stability and upper mixed layer depth (UMLD). These environmental variables were reasonably informative to explain the variability of the phytoplankton communities (44% of variation explained). Cluster and canonical correspondence analyses allowed discrimination of four zones (coastal, Sub-Antarctic, tropical and intermediate zones), also identifiable in the T-S diagrams and in the nutrient spatial distribution patterns. The presence of nutrient-rich Sub-Antarctic waters was a major oceanographic feature, associated with diatoms and dinoflagellates. However, in the Sub-Antarctic zone, biomass was particularly low, probably as a result of grazing pressure, as suggested by chemical and biological indicators. In contrast, in oligotrophic tropical waters, phytoplankton was mainly composed by small nanoflagellates and cyanobacteria. A large intermediate zone was also dominated by nanoflagellates, mainly Phaeocystis antarctica, probably favored by strong water column stability. The coastal zone exhibited fairly similar conditions to those in the intermediate zone, but with deeper UMLD, a favorable condition for diatom growth. These results emphasize the importance of the properties of water masses and also biological processes such as grazing in structuring phytoplankton communities in the region. © 2012 The Author. Published by Oxford University Press. All rights reserved.
De Souza M.S.,Institute Oceanografia FURG |
Mendes C.R.B.,Institute Oceanografia FURG |
Mendes C.R.B.,University of Lisbon |
Garcia V.M.T.,Institute Oceanografia FURG |
And 2 more authors.
Journal of the Marine Biological Association of the United Kingdom | Year: 2012
We describe the phytoplankton community and biomass during a summer coccolithophorid bloom sampled over the Patagonian shelf (48.5°S-50.5°S) . Those phytoplankton species can contribute to the flux of calcium carbonate out of surface waters. Results from both microscope and high-performance liquid chromatography (HPLC) analysis are shown to complement information on the phytoplankton community. From CHEMTAX analysis of HPLC data, the most important organisms and groups identified were the coccolithophorid Emiliania huxleyi, the haptophyte Phaeocystis antarctica, dinoflagellates, diatoms, cryptophytes, prasinophytes and cyanobacteria. Phytoplankton microscope counts were converted into phytoplankton group-specific biovolume estimates. Although some microscope-identified taxa could not be determined by CHEMTAX, e.g. the autotrophic ciliate Myrionecta rubra, cluster analyses from both techniques showed similar results for the main groups. Both Emiliania huxleyi cell concentration and biomass, and the pigment 19′-hexanoyloxyfucoxanthin were the most important biological features during the sampling period. At surface, nitrate was moderately high (0.2-4.2 μM) in coccolithophorid-dominated samples, whereas phosphate (<0.33 μM) and silicate (<1.35 7mu;M) concentrations were low. Among the environmental factors low Si:N ratios were mainly associated with the dominance of E. huxleyi. Competition and probably differential grazing could also promote a coccolithophorid outgrowth over other photoautotrophs during the summer season in the Patagonian shelf. Copyright © 2011 Marine Biological Association of the United Kingdom.
Niencheski L.F.,Institute Oceanografia FURG |
Moore W.S.,University of South Carolina |
Windom H.L.,Skidaway Institute of Oceanography
Marine Pollution Bulletin | Year: 2014
This study reports results of analysis of sediment cores collected from the Patos Lagoon estuary. This estuary receives materials from land runoff into Patos and Mirim lagoons and from exchange with the adjacent South Atlantic Ocean through a narrow inlet. Sediment from these sources is mostly natural, but additional contributions associated with source/activities related to the port of Rio Grande. The aim of this study was to estimate rates of accumulation of the sediments and to assess the significance of metal inputs from these activities relative to natural inputs. Our results indicate an average sedimentation rate of 0.3. cm/yr and that the transport of suspended solids from offshore sources into the estuary was enhanced after the deepening of the channel and construction of the breakwaters (in the early 1900). Results for metal accumulation in these sediments suggest that there have been only minor enrichments which can be attributed to anthropogenic sources. © 2013 Elsevier Ltd.
PubMed | University of South Carolina, Skidaway Institute of Oceanography and Institute Oceanografia FURG
Type: Journal Article | Journal: Marine pollution bulletin | Year: 2014
This study reports results of analysis of sediment cores collected from the Patos Lagoon estuary. This estuary receives materials from land runoff into Patos and Mirim lagoons and from exchange with the adjacent South Atlantic Ocean through a narrow inlet. Sediment from these sources is mostly natural, but additional contributions associated with source/activities related to the port of Rio Grande. The aim of this study was to estimate rates of accumulation of the sediments and to assess the significance of metal inputs from these activities relative to natural inputs. Our results indicate an average sedimentation rate of 0.3 cm/yr and that the transport of suspended solids from offshore sources into the estuary was enhanced after the deepening of the channel and construction of the breakwaters (in the early 1900). Results for metal accumulation in these sediments suggest that there have been only minor enrichments which can be attributed to anthropogenic sources.
Correa I.C.S.,Federal University of Rio Grande do Sul |
Medeanic S.,Institute Oceanografia FURG |
Weschenfelder J.,Federal University of Rio Grande do Sul |
Toldo Jr. E.E.,Federal University of Rio Grande do Sul |
And 3 more authors.
Revista Mexicana de Ciencias Geologicas | Year: 2013
This paper deals with the characterization of the geomorphology and paleo-evolution of a La Plata River paleochannel, located on the south Brazilian continental shelf since the Upper Pleistocene. Through a bathymetric survey and coring of sediments from the paleochannel, a sedimentological and palynological analysis was carried out. This kind of analysis allowed us to characterize a transgressive depositional sequence on the La Plata River paleochannel. The palynological sequences indicated marine environments grading to mixohaline and continental freshwater. From a sedimentological point of view, the area is characterized as a fluvial-estuarine environment. These data offer new information to reconstruct the paleogeographic evolution of the La Plata River paleochannel on the Rio Grande do Sul continental shelf (Brazil).