Mud depocentres on the continental shelf: a neglected sink for anthropogenic contaminants from the coastal zone

Mahiques, Michel Michaelovitch de; Hanebuth, Till J J; Martins, César C.; Montoya-Montes, Isabel; Alcántara‐Carrió, Javier; Figueira, Rubens César Lopes; Bı́cego, Márcia Caruso

doi:10.1007/s12665-015-4782-z

Cited by 54 publications

(28 citation statements)

References 51 publications

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“…In fact, previous studies (de Mahiques et al, 2008;Franco-Fraguas et al, 2014;Razik et al, 2015) provide different and contradictory interpretations for the sources and transport of sediment in the south-western Atlantic; this is especially due to a complex hydrodynamics of the Subtropical Gyre (Boebel et al, 1999;Schmid et al, 2000;Biló et al, 2014) between 23 and 35 • S.…”

Section: Introductionmentioning

confidence: 99%

“…The origin and fate of terrigenous sediments in continental margins can be analysed using different proxies, such as elemental composition (Govin et al, 2012), isotopes (Vroon et al, 1995;Lacan and Jeandel, 2005;de Mahiques et al, 2008), magnetic properties (Razik et al, 2015), mineralogy (Petschick et al, 1996;Wahsner et al, 1999;Nagai et al, 2014a), and even grain size (Prins and Weltje, 1999;Holz et al, 2004).…”

Section: Introductionmentioning

confidence: 99%

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Inorganic and organic geochemical fingerprinting of sediment sources and ocean circulation on a complex continental margin (São Paulo Bight, Brazil)

Mahiques¹,

Hanebuth

Nagai

et al. 2017

Ocean Sci.

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Abstract. In this study, we use inorganic (metal) and organic (bulk and molecular) markers in sediment samples of the south-eastern Brazilian margin to investigate the response of geochemical fingerprints to the complex hydrodynamic processes present in the area. Results indicate the potential of export of terrigenous siliciclastic and organic constituents to the upper slope, even in an area with limited fluvial supply.Metal contents and especially the ln(Ti ∕ Al) and ln(Fe ∕ K) ratios make it possible to recognise the extension of shelf sediments toward the upper slope. Potassium, here expressed as ln(K ∕ Sc) and ln(K ∕ Al) ratios used as proxies of illite–kaolinite variations, proved to be an important parameter, especially because it allowed us to decipher the imprint of the northward flow of the Intermediate Western Boundary Current (IWBC) in comparison to the southward flows of the Brazil Current (BC) and Deep Western Boundary Current (DWBC). Using organic matter analyses, we were able to evaluate the extent of terrestrial contributions to the outer shelf and slope, even without the presence of significant fluvial input. In addition, molecular markers signify a slight increase in the input of C4-derived plants to the slope sediments, transported from distant areas by the main alongshore boundary currents, indicating that the terrestrial fraction of the organic matter deposited on the slope has a distinct origin when compared to shelf sediments.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Inorganic and organic geochemical fingerprinting of sediment sources and ocean circulation on a complex continental margin (São Paulo Bight, Brazil)

Mahiques¹,

Hanebuth

Nagai

et al. 2017

Ocean Sci.

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“…Chemical contaminants, which could accumulate in ocean sediments, can be reinjected into the water column by disturbances (e.g., storms, animal movements, human activities) resulting in recurring contamination over time (Mahiques et al. ).…”

Section: Introductionmentioning

confidence: 99%

Brazil's worst mining disaster: Corporations must be compelled to pay the actual environmental costs

Garcia

Ribeiro

Roque

et al. 2017

Ecological Applications

158

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Abstract. In November 2015, a large mine-tailing dam owned by Samarco Corporation collapsed in Brazil, generating a massive wave of toxic mud that spread down the Doce River, killing 20 people and affecting biodiversity across hundreds of kilometers of river, riparian lands, and Atlantic coast. Besides the disaster's serious human and socioeconomic tolls, we estimate the regional loss of environmental services to be ~US$521 million per year. Although our estimate is conservative, it is still six times higher than the fine imposed on Samarco by Brazilian environmental authorities. To reduce such disparities between estimated damages and levied fines, we advocate for an environmental bond policy that considers potential risks and environmental services that could possibly be impacted by irresponsible mining activity. Environmental bonds and insurance are commonly used policy instruments in many countries, but there are no clear environmental bond policies in Brazil. Environmental bonds are likely to be more effective at securing environmental restitution than post-disaster fines, which generally are inadequate and often unpaid. We estimate that at least 126 mining dams in Brazil are vulnerable to failure in the forthcoming years. Any such event could have severe socialenvironmental consequences, underscoring the need for effective disaster-management strategies for large-scale mining operations.

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“…They represent well-resolved palaeoenvironmental accumulations, commonly initiated during early flooding of continental shelves following deglaciation ~14 ky ago(Hanebuth et al 2015). One example now forming a sink of anthropogenic pollution, including heavy metals and hydrocarbons, lies off the coast of São Paolo State, SE Brazil(Mahiques et al 2016).…”

mentioning

confidence: 99%

“…including trawler fishing and sea-bed dredging(Mahiques et al 2016). Similar shelf mud deposits occur in the Bay of Biscay, in front of the Gironde estuary, SW France(Lesueur et al 1996), where three mud-patches, totalling 630 km 2 , occupy palaeo-valleys at depths of 30−75 m. The rhythmically laminated deposits there, which broadly represent storm layers, accumulated to a thickness of 1.8 m over the last 2000 years and the upper 0.2 m accumulated in <30 years, as shown by 14 C and pollen analyses.…”

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confidence: 99%

Global Boundary Stratotype Section and Point (GSSP) for the Anthropocene Series: Where and how to look for potential candidates

Waters

Zalasiewicz

Summerhayes

et al. 2018

Earth-Science Reviews

185

132

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The Anthropocene as a potential new unit of the International Chronostratigraphic Chart (which serves as the basis of the Geological Time Scale) is assessed in terms of the stratigraphic markers and approximate boundary levels available to define the base of the unit. The task of assessing and selecting potential Global Boundary Stratotype Section and Point (GSSP) candidate sections, a required part of the process in seeking formalisation of the term, is now being actively pursued. Here, we review the suitability of different stratified palaeoenvironmental settings and facies as potential hosts for a candidate GSSP and auxiliary sections, and the relevant stratigraphical markers for correlation. Published examples are evaluated for their strengths and weaknesses in this respect. A marked upturn in abundance of radioisotopes of 239 Pu or 14 C, approximately in 1952 and 1954 CE respectively, broadly coincident with a downturn in δ 13 C values, is applicable across most environments. Principal palaeoenvironments examined include: settings associated with accumulations of anthropogenic material, marine anoxic basins, coral reefs, estuaries and deltas, lakes at various latitudes, peat bogs, snow/ice layers, speleothems and trees.Together, many of these geographically diverse palaeoenvironments offer annual/subannual laminae that can be counted and independently dated radiometrically (e.g. by 210 Pb).Examples of possible sections offer the possibility of correlation with annual/seasonal resolution. From among such examples, a small number of potentially representative sites require the acquisition of more systematic and comprehensive datasets, with correlation established between sections, to allow selection of a candidate GSSP and auxiliary stratotypes. The assessments in this paper will help find the optimal locations for these sections.

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Mud depocentres on the continental shelf: a neglected sink for anthropogenic contaminants from the coastal zone

Cited by 54 publications

References 51 publications

Inorganic and organic geochemical fingerprinting of sediment sources and ocean circulation on a complex continental margin (São Paulo Bight, Brazil)

Inorganic and organic geochemical fingerprinting of sediment sources and ocean circulation on a complex continental margin (São Paulo Bight, Brazil)

Brazil's worst mining disaster: Corporations must be compelled to pay the actual environmental costs

Global Boundary Stratotype Section and Point (GSSP) for the Anthropocene Series: Where and how to look for potential candidates

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