ORCID Profile
0000-0003-3117-8584
Current Organisation
Universidade Federal Fluminense
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Publisher: Elsevier BV
Date: 10-2022
Publisher: Sociedade Brasileira de Quimica (SBQ)
Date: 2016
Publisher: Elsevier BV
Date: 07-2017
DOI: 10.1016/J.ENVPOL.2017.04.011
Abstract: The application of zinc (Zn) isotopes in bivalve tissues to identify zinc sources in estuaries was critically assessed. We determined the zinc isotope composition of mollusks (Crassostrea brasiliana and Perna perna) and suspended particulate matter (SPM) in a tropical estuary (Sepetiba Bay, Brazil) historically impacted by metallurgical activities. The zinc isotope systematics of the SPM was in line with mixing of zinc derived from fluvial material and from metallurgical activities. In contrast, source mixing alone cannot account for the isotope ratios observed in the bivalves, which are significantly lighter in the contaminated metallurgical zone (δ
Publisher: Springer Science and Business Media LLC
Date: 31-03-2020
Publisher: Copernicus GmbH
Date: 22-04-2021
Abstract: Abstract. Hypersaline tidal flats (HTFs) are coastal ecosystems with freshwater deficits often occurring in arid or semi-arid regions near mangrove supratidal zones with no major fluvial contributions. Here, we estimate that organic carbon (OC), total nitrogen (TN) and total phosphorus (TP) were buried at rates averaging 21 (±6), 1.7 (±0.3) and 1.4 (±0.3) gm-2yr-1, respectively, during the previous century in three contrasting HTF systems, one in Brazil (eutrophic) and two in Australia (oligotrophic). Although these rates are lower than those from nearby mangrove, saltmarsh and seagrass systems, the importance of HTFs as sinks for OC, TN and TP may be significant given their extensive coverage. Despite the measured short-term variability between net air–saltpan CO2 influx and emission estimates found during the dry and wet season in the Brazilian HTF, the only site with seasonal CO2 flux measurements, the OC sedimentary profiles over several decades suggest efficient OC burial at all sites. Indeed, the stable isotopes of OC and TN (δ13C and δ15N) along with C:N ratios show that microphytobenthos are the major source of the buried OC in these HTFs. Our findings highlight a previously unquantified carbon as well as a nutrient sink and suggest that coastal HTF ecosystems could be included in the emerging blue carbon framework.
Publisher: Elsevier BV
Date: 02-2019
Publisher: Elsevier BV
Date: 2017
Publisher: Elsevier BV
Date: 06-2017
Publisher: Elsevier BV
Date: 04-2021
Publisher: Springer Science and Business Media LLC
Date: 05-09-2010
Publisher: Elsevier BV
Date: 06-2016
DOI: 10.1016/J.ENVPOL.2016.02.002
Abstract: A dated sediment core from a highly-fertilized mangrove wetland located in Cubatão (SE Brazil) presented a negative correlation between mercury (Hg) and organic carbon contents. This is an unusual result for a metal with well-known affinity to organic matter. A dilution of Hg concentrations by autochthonous organic matter explained this observation, as revealed by carbon stable isotopes signatures (δ(13)C). Mercury dilution by the predominant mangrove-derived organic matter counterbalanced the positive influences of algal-derived organic matter and clay contents on Hg levels, suggesting that deleterious effects of Hg may be attenuated. Considering the current paradigm on the positive effect of organic matter on Hg concentrations in coastal sediments and the expected increase in mangrove organic matter burial due to natural and anthropogenic stimulations of primary production, predictions on the influences of organic matter on Hg accumulation in mangrove wetlands deserve caution.
Publisher: Elsevier BV
Date: 11-2020
Publisher: Elsevier BV
Date: 03-2022
Publisher: Elsevier BV
Date: 2018
DOI: 10.1016/J.MARPOLBUL.2017.11.018
Abstract: A dated sediment core from an eutrophic mangrove area presented non-significant differences in carbon accumulation rates before (55.7±10.2gm
Publisher: Elsevier BV
Date: 08-2008
DOI: 10.1016/J.JENVRAD.2008.04.006
Abstract: Concentrations of fertilizer industry-derived P (up to 3.4%), Ca (up to 6.1%), (226)Ra (up to 744 Bq kg(-1)) and (210)Pb (up to 1317 Bq kg(-1)) at least one order of magnitude above natural levels were recorded in a sediment core from Morrão River estuary (SE Brazil). Unsupported (210)Pb (= total (210)Pb-(226)Ra) activities unexplained by atmospheric fallout and deviations from the radionuclides secular equilibrium also indicated strong anomalies. Anomalous constituents were positively correlated with each other and negatively correlated with clay mineral-bearing elements. These negative correlations were explained by a depletion of natural sediment constituents due to a dilution caused by elevated inputs of steel industry-derived elements (mainly by Fe levels up to 24%). Absolute data and normalizations by a proxy for clays (Al) and anthropogenic Fe evidenced variabilities in the quality of coastal and land-derived sediment inputs, mainly due to changes in the relative contributions from industrial sources.
Publisher: American Geophysical Union (AGU)
Date: 09-04-2014
DOI: 10.1002/2014GL059789
Publisher: Elsevier BV
Date: 08-2018
Publisher: Elsevier BV
Date: 11-2009
Publisher: Elsevier BV
Date: 09-2020
Publisher: Springer Science and Business Media LLC
Date: 28-09-2013
Publisher: MDPI AG
Date: 15-12-2021
DOI: 10.3390/JMSE9121438
Abstract: In order to determine the organic matter redox state in relation to specific sources in mangrove sediments, two 60 cm-long sediment cores were collected from mangrove-covered and mudflat zones within a mangrove forest in Peru. Sediment subs les from these cores were analyzed to determine δ13C values and C:N ratios, whereas two redox indices, namely, electrochemical (fEAOM) and spectroscopical (A1650/A3400) indices, were taken from a previous study and correlated with the geochemical indices obtained from this work. These indices may provide accurate information on sedimentary organic matter diagenesis by oxidative processes through its redox state. The results show that the electrochemical index (fEAOM) and the spectroscopical index (A1650/A3400) for mangrove-covered sediments exhibited a positive correlation with δ13C values and a negative correlation with C:N molar ratios. These correlations suggest that the more labile sedimentary organic matter derived from non-terrestrial sources is in a more oxidized state than that derived from mangrove vegetation. However, this was not valid for mudflat zones, where non-significant correlations between geochemical indices were observed. Furthermore, the results suggest that the redox state of the organic matter deposited over time is dependent on source mixing influences, being better preserved in the presence of mangrove-derived organic matter.
Publisher: FapUNIFESP (SciELO)
Date: 2012
No related grants have been discovered for Wilson Machado.