Gefäß, Tasse

Rand- und Körperfragment einer Tasse. Konkaves Oberteilprofil, scharfe Knickwand und niedriger Unterteil. Schwarze Farbe. Außen: An Schulter umlaufenden Rillen. Am Körper bis zum Knick Stempeldekor mit senkrechten Winkeln und einem Punkt innen

¹⁴C Variation of Dissolved Lignin in Arctic River Systems

Assessing permafrost-release signals in arctic rivers is challenging due to mixing of complex carbon components of contrasting ages. Compound-specific ¹⁴C analysis of terrestrially derived molecules may reduce the influence of mixed carbon sources and potentially provide a closer examination on the dynamics of permafrost-derived carbon in arctic rivers. Here we employed a recently modified method to determine radiocarbon contents of lignin phenols, as a classic tracer for terrestrial carbon, isolated from the dissolved organic matter (DOM) of two arctic river systems that showed contrasting seasonal dynamics and age components in DOM. While dissolved lignin had relatively invariant ¹⁴C contents in the Mackenzie, it was more concentrated and ¹⁴C-enriched during spring thaw but relatively diluted and ¹⁴C-depleted in the summer flow or permafrost thaw waters in the Kolyma. Remarkably, the covariance between dissolved lignin concentrations and its ¹⁴C contents nicely followed the Keeling plot, indicating mixing of a young pool of dissolved lignin with an aged pool of a constant concentration within the river. Using model parameters, we showed that although the young pool had similarly modern ages in both rivers, Kolyma had a much higher concentration of aged dissolved lignin and/or with older ages. With this approach, our study not only provided the first set of ¹⁴C data on dissolved lignin phenols in rivers but also demonstrated that the age and abundance of the old DOM pool can be assessed by radiocarbon dating of dissolved lignin in arctic rivers related to permafrost release

¹⁴C Variation of Dissolved Lignin in Arctic River Systems

Assessing permafrost-release signals in arctic rivers is challenging due to mixing of complex carbon components of contrasting ages. Compound-specific ¹⁴C analysis of terrestrially derived molecules may reduce the influence of mixed carbon sources and potentially provide a closer examination on the dynamics of permafrost-derived carbon in arctic rivers. Here we employed a recently modified method to determine radiocarbon contents of lignin phenols, as a classic tracer for terrestrial carbon, isolated from the dissolved organic matter (DOM) of two arctic river systems that showed contrasting seasonal dynamics and age components in DOM. While dissolved lignin had relatively invariant ¹⁴C contents in the Mackenzie, it was more concentrated and ¹⁴C-enriched during spring thaw but relatively diluted and ¹⁴C-depleted in the summer flow or permafrost thaw waters in the Kolyma. Remarkably, the covariance between dissolved lignin concentrations and its ¹⁴C contents nicely followed the Keeling plot, indicating mixing of a young pool of dissolved lignin with an aged pool of a constant concentration within the river. Using model parameters, we showed that although the young pool had similarly modern ages in both rivers, Kolyma had a much higher concentration of aged dissolved lignin and/or with older ages. With this approach, our study not only provided the first set of ¹⁴C data on dissolved lignin phenols in rivers but also demonstrated that the age and abundance of the old DOM pool can be assessed by radiocarbon dating of dissolved lignin in arctic rivers related to permafrost release

Radiocarbon-Based Source Apportionment of Carbonaceous Aerosols at a Regional Background Site on Hainan Island, South China

To assign fossil and nonfossil contributions to carbonaceous particles, radiocarbon (¹⁴C) measurements were performed on organic carbon (OC), elemental carbon (EC), and water-insoluble OC (WINSOC) of aerosol samples from a regional background site in South China under different seasonal conditions. The average contributions of fossil sources to EC, OC and WINSOC were 38 ± 11%, 19 ± 10%, and 17 ± 10%, respectively, indicating generally a dominance of nonfossil emissions. A higher contribution from fossil sources to EC (∼51%) and OC (∼30%) was observed for air-masses transported from Southeast China in fall, associated with large fossil-fuel combustion and vehicle emissions in highly urbanized regions of China. In contrast, an increase of the nonfossil contribution by 5–10% was observed during the periods with enhanced open biomass-burning activities in Southeast Asia or Southeast China. A modified EC tracer method was used to estimate the secondary organic carbon from fossil emissions by determining ¹⁴C-derived fossil WINSOC and fossil EC. This approach indicates a dominating secondary component (70 ± 7%) of fossil OC. Furthermore, contributions of biogenic and biomass-burning emissions to contemporary OC were estimated to be 56 ± 16% and 44 ± 14%, respectively

Accelerator mass spectrometry radiocarbon ages.

<p>Included information: Core number, publication code, sampling depth, dated material [pF = planktic foraminifera; bF = benthic foraminifera], radiocarbon age [yrs BP], standard deviation [±1σ], marine reservoir effect [MRE], calibrated years [yrs] before the present [BP].</p

Detailed multibeam swath bathymetry.

<p>Data shows the location of grounding-zone wedge ‘a’ (‘GZWa’) and glacial landforms emerging NNE from it within the deep (~800 meters below sea level) outer portion of Abbot Trough. Sediment core locations are indicated by black dots, sediment echography profiles in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0181593#pone.0181593.g004" target="_blank">Fig 4</a> are marked by lines x-x’ and y-y’. Inset shows MSGLs located in small black box in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0181593#pone.0181593.g002" target="_blank">Fig 2</a>. Grid cell size 30 m, grid illuminated from NW.</p

Map of the eastern Amundsen Sea Embayment, West Antarctica.

<p>The location of the study area is indicated by large black box in the upper right corner. The general bathymetry is based on IBCSO v. 1 data [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0181593#pone.0181593.ref027" target="_blank">27</a>]. Continuous orange line indicates the LGM grounding line position (25 ka BP; [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0181593#pone.0181593.ref023" target="_blank">23</a>])–dashed sections mark uncertain positions. Continuous green line indicates the LGM grounding line position based on this study—dashed green line marks yet uncertain sections. Locations of grounding-zone wedges (GZW) derived from Graham et al. [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0181593#pone.0181593.ref008" target="_blank">8</a>] (GZWs 1 & 2), and Klages et al. [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0181593#pone.0181593.ref013" target="_blank">13</a>] (GZWa). Thick black lines mark the axes of paleo-ice stream troughs. Locations of sediment cores described in detail for this study are indicated by red-circled black dots (cores VC453, PS69/256-1, and PS69/300-1 [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0181593#pone.0181593.ref011" target="_blank">11</a>] are indicated by red-circled white dots). Lines x-x’ and y-y’ in inset mark the location of PARASOUND profiles in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0181593#pone.0181593.g004" target="_blank">Fig 4</a>. The simplified display of mega-scale glacial lineations (MSGLs), linear scours (LS), and the grounding-zone wedge ‘a’ (GZWa) in the white box in inset is based on glacial landform information presented in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0181593#pone.0181593.g003" target="_blank">Fig 3</a>, and from recent reconstructions by Klages et al. [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0181593#pone.0181593.ref013" target="_blank">13</a>]. Small black box indicates the location of MSGLs shown in the inset in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0181593#pone.0181593.g003" target="_blank">Fig 3</a>. WAIS––West Antarctic Ice Sheet; PIT(W, E)––Pine Island-Thwaites Trough (West, East); AT––Abbot Trough; BI––Burke Island; TI––Thurston Island; AIS––Abbot Ice Shelf; KP––King Peninsula; CIS––Cosgrove Ice Shelf; CP––Canisteo Peninsula; PIG––Pine Island Glacier; TG––Thwaites Glacier; mbsl––meters below sea level.</p

Sediment echography profiles and data logs for sediment cores PS75/190–3 and PS75/192-1.

<p>The cores were recovered from the upper parts of an acoustically stratified unit that overlies an acoustically transparent unit. Core data include lithology (lithological key is given above respective subbottom profiles), grain-size distribution (gravel/sand/mud), magnetic susceptibility, water content, shear strength, p-wave velocity (Vp), organic carbon content (C_org), relative palaeointensity (RPI_ARM(14-50mT)) in standardized form (only for PS75/190-3 –M.L.E. = ‘Mono Lake Excursion’; L.E. = ‘Laschamp Excursion’), facies (described in text), and calibrated (cal.) accelerator mass spectrometry radiocarbon ages of mixed benthic/planktic calcareous foraminifera in kiloyears before present (ka BP). The age models for the cores are displayed in boxes ‘Age- depth plot’ (red crosses refer to ages obtained from gravity cores PS75/190-3 & PS75/192-1; blue crosses: PS75/192-3; age uncertainties are indicated by black bars; dates with asterisk indicate duplicate dates for samples PS75/190-3 200 centimeter below seafloor (cmbsf) and PS75/192-1 214 cmbsf; stratigraphic locations of M.L.E. and L.E. are indicated by green dots).</p

Video1_The impact of Holocene deglaciation and glacial dynamics on the landscapes and geomorphology of Potter Peninsula, King George Island (Isla 25 Mayo), NW Antarctic Peninsula.MP4

The timing and impact of deglaciation and Holocene readvances on the terrestrial continental margins of the Antarctic Peninsula (AP) have been well-studied but are still debated. Potter Peninsula on King George Island (KGI) (Isla 25 de Mayo), South Shetland Islands (SSI), NW Antarctic Peninsula, has a detailed assemblage of glacial landforms and stratigraphic exposures for constraining deglacial landscape development and glacier readvances. We undertook new morphostratigraphic mapping of the deglaciated foreland of the Warszawa Icefield, an outlet of the Bellingshausen (Collins) Ice Cap on Potter Peninsula, using satellite imagery and new lithofacies recognition and interpretations, combined with new chronostratigraphic analysis of stratigraphic sections, lake sediments, and moraine deposits. Results show that the deglaciation on Potter Peninsula began before c. 8.2 ka. Around c. 7.0 ka, the Warszawa Icefield and the marine-facing Fourcade Glacier readvanced across Potter Peninsula and to the outer part of Potter Cove. Evidence of further readvances on Potter Peninsula was absent until the Warszawa Icefield margin was landward of its present position on three occasions: c. 1.7–1.4 ka, after c. 0.7 ka (most likely c. 0.5–0.1 ka), and by 1956 CE. The timing of Holocene deglaciation and glacier fluctuations on Potter Peninsula are broadly coeval with other glacier- and ice-free areas on the SSI and the northern AP and likely driven by interactions between millennial–centennial-scale changes in solar insolation and irradiance, the southern westerlies, and the Southern Annular Mode.</p

DataSheet1_The impact of Holocene deglaciation and glacial dynamics on the landscapes and geomorphology of Potter Peninsula, King George Island (Isla 25 Mayo), NW Antarctic Peninsula.pdf

The timing and impact of deglaciation and Holocene readvances on the terrestrial continental margins of the Antarctic Peninsula (AP) have been well-studied but are still debated. Potter Peninsula on King George Island (KGI) (Isla 25 de Mayo), South Shetland Islands (SSI), NW Antarctic Peninsula, has a detailed assemblage of glacial landforms and stratigraphic exposures for constraining deglacial landscape development and glacier readvances. We undertook new morphostratigraphic mapping of the deglaciated foreland of the Warszawa Icefield, an outlet of the Bellingshausen (Collins) Ice Cap on Potter Peninsula, using satellite imagery and new lithofacies recognition and interpretations, combined with new chronostratigraphic analysis of stratigraphic sections, lake sediments, and moraine deposits. Results show that the deglaciation on Potter Peninsula began before c. 8.2 ka. Around c. 7.0 ka, the Warszawa Icefield and the marine-facing Fourcade Glacier readvanced across Potter Peninsula and to the outer part of Potter Cove. Evidence of further readvances on Potter Peninsula was absent until the Warszawa Icefield margin was landward of its present position on three occasions: c. 1.7–1.4 ka, after c. 0.7 ka (most likely c. 0.5–0.1 ka), and by 1956 CE. The timing of Holocene deglaciation and glacier fluctuations on Potter Peninsula are broadly coeval with other glacier- and ice-free areas on the SSI and the northern AP and likely driven by interactions between millennial–centennial-scale changes in solar insolation and irradiance, the southern westerlies, and the Southern Annular Mode.</p