Is there a Technique for the Determination of Sedimentation Rates based on Calcium Carbonate Content? A Comparative Study on the Southeastern Brazilian Shelf

Figueira, Rubens César Lopes; Tessler, Moysés Gonsalez; Mahiques, Michel Michaelovitch de; Fukumoto, Marina Midori

doi:10.3208/sandf.47.649

Cited by 34 publications

(25 citation statements)

References 18 publications

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“…Elemental preparation and analysis (As, Cd, Cr, Cu, Ni, Pb, Sc and Zn) followed SW-846 methodologies (USEPA, 1996(USEPA, , 2007, applying ICP-OES technique (Varian MPX 710ES model). Geocronology was determined via gamma spectrometry, by 210 Pb xs and 137 Cs methods, using a low background Ge detector, EG&G Ortec, model GMX 25190P, as described by Figueira et al (2007).…”

Section: Introductionmentioning

confidence: 99%

Evaluation of anthropic influences in an estuarine system of Southeastern Brazilian Coast by applying enrichment factors

Gonçalves¹,

Figueira²,

Sartoretto³

et al. 2013

E3S Web of Conferences

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Abstract. This study presents an evaluation of metals and As deposition in the Bertioga Channel (Santos Region, Southeastern Brazilian coast) along the last 150 years, which corresponds to the main anthropogenic activity in the area. The studied area is located in the so-called Baixada Santista, where the main Brazilian harbor and one of the most important industrial centers of the country are located. This work consisted of sampling five sediment cores along this channel. The cores were sliced every 2 cm, and the samples were analyzed by ICP-OES to determine the levels of heavy metals (Cd, Cr, Cu, Ni, Pb and Zn) and As. The enrichment factors (EF) were calculated to identify the relative heavy-metal toxicity of the sediments and the anthropogenic contribution of the investigated elements. EFs indicated the absence of contamination for the heavy metals but a higher input of As in two cores (B2 and B5). According to the age models of the cores, this enrichment corresponds to the end of the 19 th century, when Santos harbor was inaugurated, and to the 1970s, when Santos harbor activities expanded.

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Section: Introductionmentioning

confidence: 99%

Evaluation of anthropic influences in an estuarine system of Southeastern Brazilian Coast by applying enrichment factors

Gonçalves¹,

Figueira²,

Sartoretto³

et al. 2013

E3S Web of Conferences

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“…Determination of the chronology and sedimentation rates was obtained via 210 Pb gamma spectrometry by analyzing its photopeak at 47 keV using a low background Ge detector (EG&G Ortec model GMX 25190P), as described in Figueira et al (2007). The calculation of the sedimentation rate based on the unsupported Pb was made via the CIC (Concentration Initial Constant) Model (Appleby andOldfield 1978, Joshi andShukla 1991).…”

Section: Chronologymentioning

confidence: 99%

Coastline changes and sedimentation related with the opening of an artificial channel: the Valo Grande Delta, SE Brazil

Mahiques

Figueira

Alves

et al. 2014

An. Acad. Bras. Ciênc.

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The role played by human activity in coastline changes indicates a general tendency of retreating coasts, especially deltaic environments, as a result of the recent trend of sea level rise as well as the blockage of the transfer of sediments towards the coast, especially due to the construction of dams. This is particularly important in deltaic environments which have been suffering a dramatic loss of area in the last decades. In contrast, in this paper, we report the origin and evolution of an anthropogenic delta, the Valo Grande delta, on the south-eastern Brazilian coast, whose origin is related to the opening of an artificial channel and the diversion of the main flow of the Ribeira de Iguape River. The methodology included the analysis of coastline changes, bathymetry and coring, which were used to determine the sedimentation rates and grain-size changes over time. The results allowed us to recognize the different facies of the anthropogenic delta and establish its lateral and vertical depositional trends. Despite not being very frequent, anthropogenic deltas represent a favorable environment for the record of natural and anthropogenic changes in historical times and, thus, deserve more attention from researchers of different subjects.

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“…Chronology 210 Pb and fallout 137 Cs dating were performed on bulk sediment, which had been ground to <63 µm, using an EG and G ORTEC ® low background gamma spectrometer (hyper-pure Ge, model GMX25190P) following the method described by Figueira et al [26]. Precision and accuracy were evaluated using three certified reference materials, IAEA-326 (soil), IAEA-327 (soil) and IAEA-385 (marine sediment), to determine the radionuclides of interest.…”

Section: Methodsmentioning

confidence: 99%

“…Two models were used to calculate the sedimentation rate [26]: concentration initial concentration of unsupported [26][27][28]). From that point, the depth age curve was extrapolated using the lower most calculated MAR, factoring in changes in laminate thickness [29].…”

Section: Methodsmentioning

confidence: 99%

Effect of the Little Ice Age on Climate and Vegetation Recorded by n-Alkanes and Glycerol Dialkyl Glycerol Tetraether Proxies

Machado¹,

Froehnerb²

2015

J Earth Sci Clim Change

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Keywords: Climatic changes; Little ice age; n-Alkane distributions; GDGT proxies IntroductionThe period which was subjected to much colder winters followed by warmer periods is known as the little ice age (LIA). It documented as being between about 1300 and 1870 (Mann, 2002). However, climate change could vary geographically [1]. The period is divided into two phases; the first was around 1300 until the late 1400s and the second warmer period was in in the 1500s [2]. The period between 1600 and 1850 marks its height and was characterized by changes in the hydrological cycle and perturbation of the ecosystem [2-4].Even although there much evidence for the LIA, the causes and mechanism are still under debate. The only certainty is that it was a global event. Most studies have focused on the northern hemisphere [3][4][5], and there are few studies demonstrating the occurrence of the event in the southern hemisphere. For instance, in South America [6,7], advance in glaciers in the Andes was demonstrated [8], as well as aridity in the lowlands of Argentina [9] and Venezuela [8], and there is evidence from mountain glaciers suggesting increasing glaciation in Patagonia [10]. In Brazil, some studies have demonstrated change in vegetation composition during the LIA and sea level regression in northeastern and southeastern Brazil [11][12][13].At present, paleoclimate can be reconstructed due the widespread occurrence of biomarkers multi-proxy data derived from them. The spatial and temporal character of such putative climate epochs revived the discussion and understanding of and mechanism for the LIA, as well as of the implications for climate change in the future.Typically, n-alkanes are derived from different sources (algae, photosynthetic bacteria and higher plants [14]. Different distribution patterns of n-alkanes in sediments provides information about different climatic environments and hence is widely used to understand the evolution of vegetation and reconstruct environmental changes [14,15]. The magnitude of the anthropogenic impact on the climate and the environment was recently measured from biomarker distributions [4,14]. Yet, some biomarkers can be more specific in their information than n-alkanes. For example, increasing attention has been driven to glycerol dialkyl glycerol tetraether (GDGT) compounds, polar basic constituents of the cell membrane and comprising a polar head group bonded to a non-polar hydrocarbon [16]. The structures of GDGTs are temperature dependent. When temperature increases, cyclopentane moieties are formed within the isoprenoid chain [17]. With more cyclopentane rings, the membrane is kept in a liquid crystalline state and, as a consequence, proton permeation is reduced.According to Weijers et al. [18] there are some environmental controls on the distributions of GDGTs, so two indices were proposed for quantifying the degree of methylation (MBT) and cyclization (CBT), both being effective in palaeoenvironmental studies to reconstruct mean annual air temperature (MAAT). Since branche...

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Is there a Technique for the Determination of Sedimentation Rates based on Calcium Carbonate Content? A Comparative Study on the Southeastern Brazilian Shelf

Cited by 34 publications

References 18 publications

Evaluation of anthropic influences in an estuarine system of Southeastern Brazilian Coast by applying enrichment factors

Evaluation of anthropic influences in an estuarine system of Southeastern Brazilian Coast by applying enrichment factors

Coastline changes and sedimentation related with the opening of an artificial channel: the Valo Grande Delta, SE Brazil

Effect of the Little Ice Age on Climate and Vegetation Recorded by n-Alkanes and Glycerol Dialkyl Glycerol Tetraether Proxies

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