210Pb and210Po analysis in sediments and soils by microwave acid digestion

Sanchez-Cabeza, Joan-Albert; Masqué, Pere; Ani-Ragolta, I.

doi:10.1007/bf02386425

Cited by 203 publications

(100 citation statements)

References 12 publications

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“…Sediment samples from both the fishing grounds and the control sites at ∼500-m water depth were subsampled (every centimeter down to 10 cm in depth) and freeze-dried, to obtain the vertical profiles of the dry bulk density (ratio of dry weight to volume of the wet sediment slice), as a proxy for sediment compaction. To estimate net accumulation of recently deposited sediments, the activities of the radionuclide 210 Pb (half-life, 22.3 y) were determined by counting the α-emission of its radioactive product 210 Po (56). To obtain the total organic C sedimentary contents (as percentages of total dry weight), aliquots of dried sediment from the top 10 cm of selected sediment were first decalcified by fuming with concentrated HCl for 48 h at 40°C.…”

Section: Methodsmentioning

confidence: 99%

Chronic and intensive bottom trawling impairs deep-sea biodiversity and ecosystem functioning

Pusceddu

Bianchelli

Martín

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

282

228

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Bottom trawling has many impacts on marine ecosystems, including seafood stock impoverishment, benthos mortality, and sediment resuspension. Historical records of this fishing practice date back to the mid-1300s. Trawling became a widespread practice in the late 19th century, and it is now progressively expanding to greater depths, with the concerns about its sustainability that emerged during the first half of the 20th century now increasing. We show here that compared with untrawled areas, chronically trawled sediments along the continental slope of the north-western Mediterranean Sea are characterized by significant decreases in organic matter content (up to 52%), slower organic carbon turnover (ca. 37%), and reduced meiofauna abundance (80%), biodiversity (50%), and nematode species richness (25%). We estimate that the organic carbon removed daily by trawling in the region under scrutiny represents as much as 60-100% of the input flux. We anticipate that such an impact is causing the degradation of deepsea sedimentary habitats and an infaunal depauperation. With deep-sea trawling currently conducted along most continental margins, we conclude that trawling represents a major threat to the deep seafloor ecosystem at the global scale.

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Section: Methodsmentioning

confidence: 99%

Chronic and intensive bottom trawling impairs deep-sea biodiversity and ecosystem functioning

Pusceddu

Bianchelli

Martín

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

282

228

View full text Add to dashboard Cite

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“…210 Pb was determined in the first five centimetres of both cores to obtain the most recent maximum sedimentation rates. Determination of 210 Pb activities was accomplished through measurement of its daughter nuclide, 210 Po, following the methodology described by Sánchez-Cabeza et al (1998). Briefly, after addition of a given amount of 209 Po as the internal tracer, sediment aliquots of 200-300 mg of each sample were totally dissolved in an acid medium using an analytical microwave oven.…”

Section: Twomentioning

confidence: 99%

“…Bond et al, 1997;Bianchi and McCave, 1999), Mediterranean (e.g. Casford et al, 2001;Rohling et al, 2009), Tropical Atlantic (e.g. deMenocal et al, 2000Rimbu et al, 2004), and Antarctic deep sea cores (e.g.…”

Section: Introductionmentioning

confidence: 99%

Tracking climate variability in the western Mediterranean during the Late Holocene: a multiproxy approach

et al. 2011

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Abstract. Climate variability in the western Mediterranean is reconstructed for the last 4000 yr using marine sediments recovered in the west Algerian-Balearic Basin, near the Alboran Basin. Fluctuations in chemical and mineralogical sediment composition as well as grain size distribution are linked to fluvial-eolian oscillations, changes in redox conditions and paleocurrent intensity. Multivariate analyses allowed us to characterize three main groups of geochemical and mineralogical proxies determining the sedimentary record of this region. These three statistical groups were applied to reconstruct paleoclimate conditions at high resolution during the Late Holocene. An increase in riverine input (fluvial-derived elements -Rb/Al, Ba/Al, REE/Al, Si/Al, Ti/Al, Mg/Al and K/Al ratios), and a decrease in Saharan eolian input (Zr/Al ratio) depict the Roman Humid Period and the Little Ice Age, while drier environmental conditions are recognized during the Late Bronze Age-Iron Age, the Dark Ages and the Medieval Climate Anomaly. Additionally, faster bottom currents and more energetic hydrodynamic conditions for the former periods are evidenced by enhanced sortable silt (10-63 µm) and quartz content, and by better oxygenated bottom waters -as reflected by decreasing redox-sensitive elements (V/Al, Cr/Al, Ni/Al and Zn/Al ratios). In contrast, opposite paleoceanographic conditions are distinguished during the latter periods, i.e. the Late Bronze Age-Iron Age, the Dark Ages and the Medieval Climate Anomaly. Although no Ba excess was registered, other paleoproductivity indicators Correspondence to: V. Nieto-Moreno (vanesanieto@ugr.es) (total organic carbon content, Br/Al ratio, and organometallic ligands such as U and Cu) display the highest values during the Roman Humid Period, and together with increasing preservation of organic matter, this period exhibits by far the most intense productivity of the last 4000 yr. Fluctuations in detrital input into the basin as the main process managing deposition, reflected by the first eigenvector defined by the Principal Component Analyses, point to solar irradiance and the North Atlantic Oscillation variability as the main driving mechanisms behind natural climate variability over decadal to centennial time-scales for the last 4000 yr.

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“…Analyses of the sediment samples were performed by total digestion of 200-300 mg using the methodology described by Sanchez-Cabeza et al (1998). 210 Po was added to each sample before digestion, as an internal tracer, and Polonium isotopes were counted with an alpha spectrometer equipped with low-background silicon surface barrier (SSB) detectors (EG&G Ortec).…”

Section: Accepted M Manuscriptmentioning

confidence: 99%

“…The sediment accumulation rate from this core was estimated from 210 Pb concentration profiles. 210 Pb activities were determined through the measurement of its daughter nuclide 210 Po, which is assumed to be in radioactive equilibrium with 210 Pb in the sediment samples, using a method modified after Nittrouer et al (1979).Analyses of the sediment samples were performed by total digestion of 200-300 mg using the methodology described by Sanchez-Cabeza et al (1998). 210 Po was added to each sample before digestion, as an internal tracer, and Polonium isotopes were counted with an alpha spectrometer equipped with low-background silicon surface barrier (SSB) detectors (EG&G Ortec).…”

mentioning

confidence: 99%

Space-for-time substitution and the evolution of a submarine canyon–channel system in a passive progradational margin

et al. 2014

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Please cite this article as: Micallef, Aaron, Ribó, Marta, Canals, Miquel, Puig, Pere, Lastras, Galderic, Tubau, Xavier, Space-for-time substitution and the evolution of a submarine canyon-channel system in a passive progradational margin, Geomorphology (2014), doi: 10.1016/j.geomorph.2014.06.008 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPT1 Manuscript submitted to Geomorphology:Space-for-time substitution and the evolution of a submarine canyon-channel system in a passive progradational margin. A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPT2 AbstractSpace-for-time substitution is a concept that has been widely applied, but not thoroughly tested in some fields of geomorphology. The objective of this study is to test whether the concept of space-for-time substitution is valid in reconstructing the evolution of a submarine canyonchannel system in a passive progradational margin. We use multibeam echosounder data and in situ measurements from the south Ebro Margin to analyse the morphology and morphometry of a sequence of submarine valleys ordered in terms of increasing valley thalweg length. The morphological model of submarine valley evolution that we can propose from this analysis is very similar to established models in the literature, which leads us to conclude that time can be substituted by space when reconstructing the evolution of submarine canyon and channel systems in the south Ebro Margin. By extracting morphometric information from the application of the space-for-time substitution model to our data, we identify a series of morphological patterns as a submarine canyon evolves in a passive progradational margin. These include the geometric similarity of canyon planform shape, an increase in canyon draining efficiency and in the influence of flank slope failures, and an evolution towards equilibrium between canyon form and imposed water and sediment load without net erosion or deposition taking place. We also observe that canyon elongation is higher downslope and that the canyon undergoes an early stage of rapid incision similar to the process of "erosion narrowing" reported in terrestrial rivers. We demonstrate that the conclusions of our study are not limited to submarine valleys in the south Ebro Margin but are applicable to other margins around the world. A C C E P T E D M A N U S C R I P TACCEPTED MANUSCRIPT 3 IntroductionGeoscientists are generally unable to fully observe landscape-forming processes because the time-scale of the observer and the time-scale of many geomorphic phenomena are very different.One approach to...

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210Pb and210Po analysis in sediments and soils by microwave acid digestion

Cited by 203 publications

References 12 publications

Chronic and intensive bottom trawling impairs deep-sea biodiversity and ecosystem functioning

Chronic and intensive bottom trawling impairs deep-sea biodiversity and ecosystem functioning

Tracking climate variability in the western Mediterranean during the Late Holocene: a multiproxy approach

Space-for-time substitution and the evolution of a submarine canyon–channel system in a passive progradational margin

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