Maria Virgínia A Martins | University of Aveiro (original) (raw)

Papers (Scientific Journals) by Maria Virgínia A Martins

This work studies the Buracica Stage (Barremian, Early Cretaceous) in the Recôncavo Basin, Bahia ... more This work studies the Buracica Stage (Barremian, Early Cretaceous) in the Recôncavo Basin, Bahia State (N.E. Brazil), comprising the São Sebastião and Pojuca formations, from the analysis of 143 well logs and outcrop records. The Recôncavo Basin is a rift basin associated with the beginning of the South Atlantic Ocean. The basin started with very slow subsidence rates, leading to the formation of shallow lakes and the deposition of shales and sandstones, which compose the Brotas Group; later, subsidence accelerated and gave rise to the formation of a deep lake. Then the deep lake basin was filled throughout six depositional episodes making up the so-called Recôncavo tectonic sequence. Previous studies divided the last depositional event of Recôncavo Basin into seven fourth-order sequences concerning the Marker Bed "1" to the Marker Bed "F" stratigraphic interval. Sequence boundaries were marked by sharp flooding surfaces related to the transgression of lacustrine system due to rapid tectonic subsidence and generation of accommodation. In turn, the sequences are divided into three systems tracts: the lake lowstand systems tract, the transgressive systems tract and the lake highstand systems tract. The maximum flood surface of the sequences generally coincides with the stratigraphic marker "B" to "F". Depositional systems like braided-fluvial plus eolian dunes, meandering-fluvial, deltaic, or moving-lake and near-shore deposits were identified in this work. Isopach, isolith and sand percentage maps indicate depocentre and source area distribution like the previous Aratu Stage. The primary sources of the sediments are located in the west and north areas; only from the third sequence, an eastern source could be described conspicuously. The fourth-order cyclicity is controlled by lake level changes, related to climatic factors (Milankovitch cycles). The results from the studies of cyclicity confirm the proposed stratigraphic model. They indicate 43,000 years for each fourth-order sequence and 150,000 years for the third-order sequences, which provide an accumulation rate of 1200 mm per 1000 years for the studied interval.

São Paulo, UNESP, Geociências, 2020

RESUMO-O Complexo Pedra Branca (CPB) está localizado na zona oeste da cidade do Rio de Janeiro (S... more RESUMO-O Complexo Pedra Branca (CPB) está localizado na zona oeste da cidade do Rio de Janeiro (SE Brasil) e está inserido tectonicamente no Domínio Costeiro, pertencente ao Terreno Oriental da Faixa Ribeira Central. Os litotipos que formam o CPB foram gerados em eventos relacionados à Orogênese Brasiliana (~600 Ma), abrigando assim rochas pré-a pós-colisionais. Estudos anteriores de corpos graníticos pós-tectônicos na Faixa Ribeira revelaram que o magmatismo ocorreu em dois pulsos distintos, com intervalo de aproximadamente 30 Ma entre eles. O presente estudo analisou 9 amostras do CPB, através dos métodos geocronológicos U-Pb e Lu-Hf via LA-ICP-MC-MS, referentes às litologias granito Pedra Branca e granito Favela, possíveis representantes do pulso mais antigo e mais jovem, respectivamente, buscando melhorar a compreensão do magmatismo pós-tectônico na região. As médias das idades encontradas para o granito Pedra Branca (509 ± 5 Ma) e granito Favela (489 ± 6 Ma) corroboraram com os valores descritos na literatura e indicaram que o magmatismo ocorrido no CPB teve origem na forma de pulsos progressivos, porém num intervalo de tempo menor (~20 Ma) do que foi anteriormente determinado. O indicador petrogenético εHf indicou participação de fontes crustais e mantélicas, dando caráter bimodal ao magmatismo registrado no CPB. Palavras-chave: Geocronologia. Magmatismo. Isótopos. LA-MC-ICP-MS. Zircão. ABSTRACT-The Pedra Branca Complex is located at the western region of the Rio de Janeiro city (SE Brazil). Tectonically it is inserted in the Coastal Domain, which is part of the central segment of the Ribeira Belt. The lithologies that formed this rocky complex were generated in events related to the Brasiliano Orogeny (~ 600 Ma), thus contains pre-to-post-collisional rocks. Previous studies on post-tectonic granite bodies belonging to Ribeira belt revealed that the magmatism occurred in two distinct pulses, with an interval of approximately ~ 30 Ma between them. The present study analyzed 9 CPB samples, using the U-Pb and Lu-Hf through LA-ICP-MC-MS geochronological methods, with focus on the Pedra Branca granite and Favela granite, which may represent the older and the younger pulses respectively, in order to improve the understanding of the post-tectonic magmatism in the area. The average ages found for the Pedra Branca (509 ± 5 Ma) and Favela (489 ± 6 Ma) granites confirm the previously described ages in the literature. However, they indicate that the magmatism in CPB occurred in the form of progressive pulses, with an interval between both events of ~ 20 Ma, that is, less than what was previously estimated (of ~ 30 Ma). In addition, the petrogenetic indicator εHf indicated the participation of crustal and mantle sources, which gives a bimodal character to the magmatism registered in the CPB.

Virgínia A. Martins, José F. Santos, Andreas Mackensen, João Alveirinho Dias, Sara Ribeiro, João ... more Virgínia A. Martins, José F. Santos, Andreas Mackensen, João Alveirinho Dias, Sara Ribeiro, João C. Moreno, António M. Soares, Fabrizio Frontalini, Daniel Rey, Fernando Rocha (2013) - The sources of the glacial IRD in the NW Iberian Continental Margin over the last 40 ka. Quaternary International, 318:128–138. DOI: 10.1016/j.quaint.2013.08.026
In this work, the first results of ice rafted detritus (IRD) provenance related to Heinrich Events in the NW Iberian Margin are presented and discussed. This study is based on multi-proxies, namely on thorough analyses of Sr and Nd isotope ratios measured in the detrital fraction of the sediment core KC 024-19, from the Galician continental slope (NE Atlantic), aiming to unravel the sources of the terrigenous component of the sampled sediments.
In most of the core layers, the isotope signatures are consistent with an origin, ultimately, in the nearby Variscan continental crust. However, allochthonous contributions were also deposited, namely during the last four Heinrich Events (HE). The non-carbonate detrital fraction of the sediments deposited during the HE1 (in its upper part), HE2, and HE4 displays 3Nd much lower than usual, suggesting that those layers incorporate clasts dropped by icebergs (Ice-Rafted Detritus e IRD) whose sources must have been located in Archaean cratons, such as those of northeastern America and Greenland. The low-3Nd values combined with dolomite peaks support the hypothesis that icebergs fed by the Laurentide ice sheet and launched through Hudson Strait played a major role in the deposition of IRD during HE1, HE2, and HE4. The HE1 layer seems to record a complex evolution of this event, since, at its base, the coarse- grained non-carbonate fraction displays relatively high-3Nd values, pointing to European/Icelandic sources for the icebergs in the initial stages of HE1. The IRD content of the HE3 contrasts significantly with the other HE layers and the non-IRD layers because it has an isotope signature characterized by low 87Sr/86Sr ratios and high-3Nd values. This suggests that the most exotic components of the HE3 layer may have come from East Greenland e Fram Strait and/or result from a mixture of materials from western European and more juvenile (Iceland e Faeroes) crustal sources.

doi:10.3906/yer-1112-12 Authors: Virgínia Martins; Fernando Rocha; Cristina Sequeira; Paula Marti... more doi:10.3906/yer-1112-12
Authors: Virgínia Martins; Fernando Rocha; Cristina Sequeira; Paula Martins; José Santos; João A. Dias; Olivier Weber; Jean-Marie Jouanneau; Belén Rubio; Daniel Rey; Ana Bernabeu; Eduardo Silva; Lazaro Laut; Rubens Figueira
This work aims to study recent climatic oscillations and their influence on sedimentation in the Ria de Vigo, a coastal embayment in Galicia, NW Spain. It is based on the study of clay mineral assemblages, in conjunction with other proxies (granulometric, geochemical, geochronological and microfaunal), in the core KSGX 24. A Benthic Foraminifera High Productivity (BFHP) proxy was used to determine changes in the flux of organic matter (OM) at the bottom of the study area. Total organic carbon (TOC) content is not a suitable proxy to estimate changes in the past supply of OM due to diagenetic processes. The sedimentation was finest in 3 sections: ~ 230–214 cm, ~ 185–73 cm and ~ 20–0 cm. These muddy sections are characterised, in general, by higher proportions of detrital minerals, concentrations of several chemical elements related to lithogenic sources and BFHP values. In addition, these sections are impoverished in carbonates, Ca, Sr and La when compared with the layers with the highest sand content. The clay mineral assemblage of the studied site, characterised by the dominance of illite, intermediate concentrations of kaolinite and minor amounts of smectite and chlorite, reveals the prevalence of a typical temperate humid climate in the last 3 ka BP, the estimated age for the core base. However, the quantities of illite and chlorite increase in the muddy layers. The characteristics of these muddy layers were interpreted as representing relatively cold climatic oscillations associated with the strengthening of northerly winds and the prevalence of an upwelling regime corresponding to well-known periods, such as the first cold period of the Upper Holocene (~ 2.9 ka cal BP), the Dark Ages (between ~ 2.2 - 1.2 ka cal BP) and the Little Ice Age (~ 0.6 ka cal BP).

Papers by Maria Virgínia A Martins

Minerals

The Araçuaí and Ribeira orogens have been studied for decades, and recently, these two orogens we... more The Araçuaí and Ribeira orogens have been studied for decades, and recently, these two orogens were described as the Araçuaí–Ribeira Orogen System. Despite much work investigating this orogenic system, some issues, such as the connection between the two orogens, are still not fully understood. This work aimed to present unpublished Lu-Hf data for the Santa Angélica Intrusive Complex (SAIC) and for the host rocks that are part of the Rio Negro magmatic arc, as well as to present U-Pb ages for these rocks, thus contributing to the understanding of the geological processes that acted in the transition zone between the Araçuaí and Ribeira orogens. Two samples were collected corresponding to the magmatic arc and six samples from the Santa Angélica Intrusive Complex. The zircon grains were separated from the samples and subjected to geochronological (U-Pb) and isotopic (Lu-Hf) analysis by laser ablation-induced coupled plasma mass spectrometry (LA-ICP-MS). The geochronological data for th...

Minerals

Rondônia intrusive suites represent the youngest A-type magmatism that occurred in the SW of the ... more Rondônia intrusive suites represent the youngest A-type magmatism that occurred in the SW of the Amazon craton, with mineralizations in Sn, Nb, Ta, W, and topaz. Petrological and isotopic studies (U-Pb and Lu-Hf by LA-ICP-MS) allowed the Massangana granite to be subdivided into São Domingos facies (medium to fine biotite-granite), Bom Jardim facies (fine granite), Massangana facies (pyterlites and coarse granites) and Taboca facies (fine granites). The crystallization ages obtained were between 995.7 ± 9.5 Ma to 1026 ± 16 Ma, and the εHf values vary significantly between positive and negative, showing predominantly crustal sources for forming these rocks. Petrographic studies on ore samples indicate the action of co-magmatic hydrothermal fluids enriched in CO2, H2O, and F. These ores are characterized by endogreisens, exogreisens, pegmatites, and quartz veins that are explored in the São Domingos facies area. The endogreisens and exogreisens are formed by topaz-granites and zinnwald...

Lithos, 2021

Abstract The postcollisional magmatism in the Ribeira Belt, a collisional Orogen developed throug... more Abstract The postcollisional magmatism in the Ribeira Belt, a collisional Orogen developed through several episodes during the convergence of the Pan-African/Brasiliano Orogeny, was marked in the Eastern Terrane (Rio de Janeiro, SE Brazil) by intense granitic magmatism of Cambro-Ordovician age. This magmatism was previously divided into the Surui and Nova Friburgo suites, both interpreted as I-type granites generated by the interactions of magmas with crustal and mantle origins. This paper presents a new contribution to the understanding of the Sana Granite. It is based on the analysis of field work, mineralogical and geochemical (elemental concentrations by Inductively Coupled Plasma Emission Spectrometer, ICP-ES, and Inductively Coupled Plasma Mass Spectrometry, ICP-MS) data, and U–Pb dating and Lu–Hf isotope analyses, by Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) from the main body and one satellite of the Sana Granite. The results of this work show that the Sana Granite, previously grouped with the Nova Friburgo suite, presents petrographic, geochemical, and isotopic characteristics that do not match its initial petrogenetic interpretation. Data from this work show that the Sana Granite is composed of alkali feldspar granites, syenogranites and monzogranites. All these rocks are hololeucocratic to leucocratic, with small grains ranging from fine to coarse. They are silica-supersaturated, peraluminous, and mostly alkali-calcic rocks and plot at the limit between the ferrous and magnesian fields. Crystallization ages of 480 ± 6 million years (Ma) and 495 ± 4 Ma are obtained in the main body of the Sana Granite, while the ages obtained in the satellite body are 506 ± 10 Ma and 508 ± 5 Ma. The Hf isotope data indicate crustal sources, with depleted mantle model ages (TDM) varying between 2.22 and 1.69 Ga and eHf values ranging between −15.54 and − 6.54. The data set from this work suggests that Sana is an S-type granite formed by the partial melting of metasedimentary rocks from the dehydration of hydrous minerals, such as biotite and muscovite. This massif is composed of muscovite-bearing peraluminous granitoids (MPGs) associated with high-pressure collisional Orogens. Considering that the characteristics of the Sana Granite are incompatible with those of the Nova Friburgo suite, it is proposed to use the Sana suite to characterize S-type granites generated in the postcollisional stage of the Ribeira Belt.

Journal of Sedimentary Environments, 2020

Living (stained) benthic foraminifera from the continental shelf of Santos Basin, southeastern Br... more Living (stained) benthic foraminifera from the continental shelf of Santos Basin, southeastern Brazilian continental margin, were investigated to understand their distribution patterns and their relationship with chlorophyll-a and particulate organic matter contents. Sediments were collected from 44 to 203 m of water depth. This study analysis benthic foraminifera and abiotic data, including grain size, total organic matter, distributions of ocean chlorophyll-a and particulate organic matter. Foraminiferal diversity and richness were positively correlated to the chlorophyll-a and particulate organic carbon contents. Stations located on the southern portion of the study area and sampled during austral winter are probably under the seasonal influence of the Brazilian Coastal Current intrusion, and Rio de la Plata and Lagoa dos Patos plumes. Ammonia rolshauseni, Textularia? sp. and Gyroidina umbonata are present within the foraminifera assemblages at these stations. On the other hand, stations in the north, are characterized by the presence of Uvigerina peregrina, Quinqueloculina atlantica, Hanzawaia concentrica and Bulimina marginata, and they are influence of Cabo Frio’s southward-moving plume.

Journal of Sedimentary Environments, 2019

The coastal areas, the most populated regions in the world, are those which have undergone the gr... more The coastal areas, the most populated regions in the world, are those which have undergone the greatest human influence. In Brazilian southeastern coast, the region around Guanabara Bay (GB) is one of the most densely populated, with large cities, such as Rio de Janeiro and Niteroi, and is highly industrialized. Due to anthropic activities tones of effluents, waste and sewage is daily released in GB. Despite, several works have been performed aiming to study the current and past human influence in GB, the sources of pollutants that have impacted this bay since the late nineteenth century. This work is a new contribution aiming to identify the main sources of pollution in the northern/northeast region of GB using stable isotopes of lead (Pb) and metal concentrations during the last decades. It analyses results obtained along the core T3 collected in the northeast region of Guanabara Bay, near the Guapimirim Environmental Protected Area (known as Apa de Guapimirim), a mangrove fringe....

Journal of Sedimentary Environments, 2019

Paleoenvironmental reconstructions in coastal environments have been carried out using indicators... more Paleoenvironmental reconstructions in coastal environments have been carried out using indicators of relative sea level oscillation (RSL), among them, mollusk shells, beachrocks and sedimentary records. Data from eleven geological-geotechnical drilling cores (from 15 m to 30 m long) distributed along the Ipanema - Leblon coastline and on the edge of the Rodrigo de Freitas Lagoon and respective stratigraphic profiles were analyzed in this work. Eleven radiocarbon ages obtained from shell samples calibrated to eliminate the effect of reservoir were used to perform the time evolution of the study area.The obtained results allowed to identify five distinct stages on the sedimentary evolution of the Southern Zone of the Rio de Janeiro City related to the Holocene RSL variations: the first stage under continental environmental conditions, with sea level approximately 4.5 m below the current; the second stage corresponding to a paleo-cove formed due to the sea level rising; the third stage...

Continental Shelf Research, 2014

ABSTRACT This study aims to explore the hydrodynamic factors that influence the depositional proc... more ABSTRACT This study aims to explore the hydrodynamic factors that influence the depositional processes on the upper continental margin of southeastern South America. Mineralogy and the activities of natural (40K) and artificial (137Cs) radionuclides from surface sediment samples were used to evaluate the provenance and oceanographic controls on depositional processes. High values of the smectite/illite (S/I) ratio indicate that the Rio de la Plata (RdlP) is a major source of terrigenous sediments to the continental shelf between 38°S and 27°S and that its importance decreases towards lower latitudes. This is also corroborated by the high radionuclide 40-K activity found in muddy sediments. The kaolinite/illite (K/I) ratio highlights the interplay between two hydrodynamic controls in the sediment distribution of the study area: (i) the Brazil Current, which supplies the shelf mostly in the northern portion of the study area with kaolinite-enriched clay minerals from tropical regions, and (ii) the Brazil Coastal Current, which transports the clay minerals, mainly illite and smectite, from the RdlP to the southern portion of the study area (up to 27°S). This is also corroborated by high 137-Cs activities. In the deeper parts (&gt;300 m) of the study area, high calcite content indicates the progressive decrease in terrigenous input towards the outer shelf and upper slope.

Continental Shelf Research, 2014

ABSTRACT The vertical distribution (0 to 100 m) of planktonic foraminifera was investigated based... more ABSTRACT The vertical distribution (0 to 100 m) of planktonic foraminifera was investigated based on 40 tow samples that were collected in 8 stations, during the austral summer of 2002, in a geographically restricted area (23°S–25°S and 40°W–44°W) on the southeastern Brazilian continental margin. Species&#39; abundances are low (less than 10 specimens/m3), which is typical of an oligotrophic area. The foraminifera assemblage is mainly composed of warm water species (Globigerinoides ruber white and pink forms), with a predominance of spinose and symbiont-bearing species. Temperature and inorganic nutrient enrichment of the surface are the main factors that control foraminiferal abundance and diversity; nevertheless salinity can also influence the ecological descriptors. The role of the deep chlorophyll maximum (DCM) in the distribution of foraminifera is not always clear, but the increase in the abundance of G. ruber (white and pink) seems to be related to a deeper DCM, and high salinities (S&gt;36.5). The ecological habitat of these species is affected by the depth of the mixed layer, with a predominance of the white form in deeper layers. Increases in the foraminiferal diversity are related to the dynamics of the Brazil Current system, which displaces the area of high productivity in the euphotic zone off the coast. The abundances of Globigerina bulloides, Globigerina falconensis, Globigerinella calida and Globigerinella siphonifera follow the nutrient enrichment of the surface water mass, corroborating the usefulness of these species as paleoproductivity proxies in the study area. These data confirm the use of diversity measurements and assemblages composition for reconstructing past water column structures in subtropical oceans.

Journal of Human and Environment of Tropical Bays, 2020

A Baía de Guanabara, um dos mais importantes sistemas costeiros do sudeste brasileiro, com os seu... more A Baía de Guanabara, um dos mais importantes sistemas costeiros do sudeste brasileiro, com os seus primeiros rasgos estruturais durante o pré-cambriano e instalação definitiva durante o Cenozoico, tem vindo a ser modelada por processos relacionados com alterações climáticas e mais recentemente pela forte atividade antrópica, na região. Este trabalho pretende efetuar uma síntese de registros sedimentares históricos relacionados com a ação antrópica no entrono da Baía de Guanabara e definir o início do Antropoceno neste sistema costeiro.Em adição, os resultados desta investigação permitem a divisão do Antropoceno em quatro periodos de sedimentação na Bia da Guanabara.A documentação e os dados analisados permitem considerar que a camada sedimentar que marca o início do Antropoceno, na Baía de Guanabara foi depositada em 1502 (Ano Domine), no decurso da “Pequena Idade do Gelo”, ano a partir do qual teve início o processo de ocupação colonialista dos Portugueses. Esforços de ocupação e ...

Marine Environmental Research, Dec 1, 2021

The main environmental variables controlling benthic foraminiferal distributions were identified ... more The main environmental variables controlling benthic foraminiferal distributions were identified and used to assess their influence on ecological indices developed as predictors of Ecological Quality Status (EcoQS) in marine ecosystems. Gradient forest and random forest models were applied to assess the predictive value of a selection of abiotic (environmental) and biotic (foraminifera) variables in a costal marine area in the central Adriatic Sea (Italy). This approach yields evidence that the predictor variables sand, silt, Pollution Load Index, and TN have the greatest influence on the distribution of benthic foraminifera in this area. In addition, we identify thresholds for the most important environmental variables that influence ecological indices. These findings contribute to efforts to determine how to best improve sediment quality and environmental stability for marine conservation. Further application of these approaches represents a useful tool for policymakers to survey the diversity of marine organisms and to improve the ability to protect and restore marine ecosystems by identifying predictors of diversity and identifying key thresholds in these predictors.

Journal of Sedimentary Environments, 2016

Graphic Computer and the three dimensional technique (3D) has its applicability in various fields... more Graphic Computer and the three dimensional technique (3D) has its applicability in various fields of science, such as: medicine, zoology, botany and paleontology. In the paleontology field it has been applied, mainly in the study of vertebrates and invertebrates fossils. The 3D-models of the scanned fossils by computed microtomography (micro-CT) allow to observe full details of its internal and external morphology. The three-dimensional model of the species provides great detailing of internal and external structures, which can contribute to a better understanding and characterization of morphological features of the analyzed materials. This work aims to detail the morphology of Pyrgo depressa (d'Orbigny, 1826) (benthic foraminifera) using the micro-CT technics. Results of imagens and of the 3D-modells obtained by micro-CT analysis allowed the observation of the initial and later chambers arrangement, the proloculus with a columnar structure and two apertures, the sequence and linearization of the apertures and toothplates of the following chambers, the walls thickness and density. The 3D-models also allow to deduce the function of teeth which is related to the initial formation of the peripheral keel.

Marine Pollution Bulletin, Mar 1, 2017

Metal concentrations in sediments were investigated in the Gulf of Tunis, Tunisia, in relation to... more Metal concentrations in sediments were investigated in the Gulf of Tunis, Tunisia, in relation to anthropic activities along the Mejerda River and Ghar El Melh Lagoon, with effluents discharged into the gulf. Distribution of grain size showed that the silty fraction is dominant with 53%, while sand and clay averages are 34 and 12% respectively. Zn concentration increased in the vicinity of the Mejerda River while Pb was at its highest levels at the outlet of Ghar El Mehl Lagoon. Sediment elutriate toxicity, as measured by oyster embryo bioassays, ranged from 10 to 45% abnormalities after 24 h, but no relation was found between metal concentration and sediment toxicity. The AVS fraction that represents monosulfide concentrations in the sediment was higher in the central part of the gulf than in the coastal zone. The results reveal the influence of AVS, TOC and grain size on metal speciation and sediment toxicity.

São Paulo, UNESP, Geociências, 2020

Minerals

Lithos, 2021

Journal of Sedimentary Environments, 2020

Journal of Sedimentary Environments, 2019

Continental Shelf Research, 2014

Journal of Human and Environment of Tropical Bays, 2020

Marine Environmental Research, Dec 1, 2021

Journal of Sedimentary Environments, 2016

Marine Pollution Bulletin, Mar 1, 2017

Environmental Science and Pollution Research, May 16, 2023

Research Square (Research Square), Sep 1, 2022

In this study, we examined the epiplastic microalgal community that developed on low-density poly... more In this study, we examined the epiplastic microalgal community that developed on low-density polyethylene (LD-PE) plastic debris found in two distinct regions of the Monastir Bay (Tunisia): the coast exposed to anthropogenic discharges and the open sea in front of the Kuriat Islands. The analysis of trace elements accumulated in the plastisphere was also carried out. The collected plastispheres were predominantly composed of cyanobacteria. Chlorophytes and diatoms were also found. Euglenophyceae was also recorded but with comparatively low relative abundance (RA), whereas dino agellates were almost absent. The diatom showed a high diversity of species (25 species). Potentially harmful microalgae (PHM) were more abundant in the plastisphere than in seawater at all stations. For all coastal area stations, most of the PHM colonizing the plastisphere are potentially harmful cyanobacteria. For S1 (offshore station), the PHM community pro le was characterized by the dominance of potentially harmful diatoms. The main potentially harmful cyanobacterium identi ed on the plastisphere was Phormidium sp. Pseudo-nitzschia spp. was the only potentially harmful diatom observed on the plastisphere. Accumulation of trace elements in plastisphere was higher than that in sediments. Trace elements in plastisphere are ranked with a very high contamination factor at all sites, according to the sequence Pb > Cu > Cd > Ni > Zn. The accumulation of trace elements in the plastisphere is highest near areas with harbor and industrial activities and the urban rejects zone.

Regional Studies in Marine Science

Geosciences = Geociências

The main aim of this work is to demonstrate that the Laser ablation multi-collector inductively c... more The main aim of this work is to demonstrate that the Laser ablation multi-collector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS) is a powerful tool for the analysis of strontium (Sr) isotopes in corals. This work discusses certification strategies for Sr isotopes determination, using reference material (RM) analyses and the results treatment based on detailed data acquired in biological materials, a coral sample. To obtain reliable results, it is essential to properly adjust the mass spectrometer and laser ablation system. Adjusting the equipment to its maximum intensity does not always result in correct 87Sr/86Sr ratios. Therefore, the optimization of the mass spectrometer was performed using the reference material NIST SRM-987 (solution) and adjusting the correct Sr isotope ratio to the reference material (USGS MACS3 and NIST-612, solids) before each analytical session. The protocol applied the solid reference material USGS MACS3 with an isotopic ratio 87Sr/86Sr of ...