scholarly journals Chronology of the Atmospheric Mercury in Lagoa da Pata Basin, Upper Rio Negro Region of Brazilian Amazon

Radiocarbon ◽  
2001 ◽  
Vol 43 (2B) ◽  
pp. 801-808 ◽  
Author(s):  
G M Santos ◽  
R C Cordeiro ◽  
E V Silva Filho ◽  
B Turcq ◽  
L D Lacerda ◽  
...  
Keyword(s):  
Forest Fires ◽  
Accumulation Rate ◽  
Atmospheric Mercury ◽  
Mercury Accumulation ◽  
Accumulation Rates ◽  
Inorganic Layer ◽  
The Core ◽  
Rio Negro ◽  
Short Period ◽  
Rapid Accumulation

We present prehistoric mercury accumulation rates in a dated sediment core from Lagoa da Pata, a remote lake in São Gabriel da Cachoeira, northern Amazon. The sediment samples were subdivided for mercury and radiocarbon analyses. A group of 18 samples have been prepared at ANU for 14C dating by accelerator mass spectrometry (AMS). The dating results show a good correlation with depth in the core, down to 41,500 BP. Three distinct sections are clearly identified in the core. They consist of upper and lower organic-rich layers, separated by an inorganic layer which represents a short period of rapid accumulation around 18 ka BP. The mercury accumulation rate is found to be larger in the upper layer (18 ka to present) than in the lower one (41 ka to 25 ka), by a factor of three. The larger accumulation rate of mercury is probably associated with warmer temperatures and a higher frequency of forest fires during the Holocene.

scholarly journals Diatom ooze—A large marine mercury sink

Science ◽  
2018 ◽  
Vol 361 (6404) ◽  
pp. 797-800 ◽  
Author(s):  
Sara Zaferani ◽  
Marta Pérez-Rodríguez ◽  
Harald Biester
Keyword(s):  
High Resolution ◽  
Southern Ocean ◽  
Marine Sediment ◽  
Crucial Role ◽  
Anthropogenic Pollution ◽  
Atmospheric Mercury ◽  
Mercury Accumulation ◽  
Accumulation Rates ◽  
Sediment Data

The role of algae for sequestration of atmospheric mercury in the ocean is largely unknown owing to a lack of marine sediment data. We used high-resolution cores from marine Antarctica to estimate Holocene global mercury accumulation in biogenic siliceous sediments (diatom ooze). Diatom ooze exhibits the highest mercury accumulation rates ever reported for the marine environment and provides a large sink of anthropogenic mercury, surpassing existing model estimates by as much as a factor of 7. Anthropogenic pollution of the Southern Ocean began ~150 years ago, and up to 20% of anthropogenic mercury emitted to the atmosphere may have been stored in diatom ooze. These findings reveal the crucial role of diatoms as a fast vector for mercury sequestration and diatom ooze as a large marine mercury sink.

Atmospheric Mercury Accumulation Rates Between 5900 and 800 Calibrated Years BP in the High Arctic of Canada Recorded by Peat Hummocks

2004 ◽  
Vol 38 (19) ◽  
pp. 4964-4972 ◽  
Author(s):  
Nicolas Givelet ◽  
Fiona Roos-Barraclough ◽  
Michael E. Goodsite ◽  
Andriy K. Cheburkin ◽  
William Shotyk
Keyword(s):  
High Arctic ◽  
Atmospheric Mercury ◽  
Mercury Accumulation ◽  
Accumulation Rates

scholarly journals A 2700-year annual timescale and accumulation history for an ice core from Roosevelt Island, West Antarctica

2019 ◽  
Vol 15 (2) ◽  
pp. 751-779 ◽  
Author(s):  
Mai Winstrup ◽  
Paul Vallelonga ◽  
Helle A. Kjær ◽  
Tyler J. Fudge ◽  
James E. Lee ◽  
...  
Keyword(s):  
Sea Ice ◽  
Accumulation Rate ◽  
Ice Core ◽  
Snow Accumulation ◽  
Accumulation Rates ◽  
West Antarctica ◽  
Sea Ice Extent ◽  
Amundsen Sea ◽  
The Core ◽  
Accumulation History

Abstract. We present a 2700-year annually resolved chronology and snow accumulation history for the Roosevelt Island Climate Evolution (RICE) ice core, Ross Ice Shelf, West Antarctica. The core adds information on past accumulation changes in an otherwise poorly constrained sector of Antarctica. The timescale was constructed by identifying annual cycles in high-resolution impurity records, and it constitutes the top part of the Roosevelt Island Ice Core Chronology 2017 (RICE17). Validation by volcanic and methane matching to the WD2014 chronology from the WAIS Divide ice core shows that the two timescales are in excellent agreement. In a companion paper, gas matching to WAIS Divide is used to extend the timescale for the deeper part of the core in which annual layers cannot be identified. Based on the annually resolved timescale, we produced a record of past snow accumulation at Roosevelt Island. The accumulation history shows that Roosevelt Island experienced slightly increasing accumulation rates between 700 BCE and 1300 CE, with an average accumulation of 0.25±0.02 m water equivalent (w.e.) per year. Since 1300 CE, trends in the accumulation rate have been consistently negative, with an acceleration in the rate of decline after the mid-17th century. The current accumulation rate at Roosevelt Island is 0.210±0.002 m w.e. yr−1 (average since 1965 CE, ±2σ), and it is rapidly declining with a trend corresponding to 0.8 mm yr−2. The decline observed since the mid-1960s is 8 times faster than the long-term decreasing trend taking place over the previous centuries, with decadal mean accumulation rates consistently being below average. Previous research has shown a strong link between Roosevelt Island accumulation rates and the location and intensity of the Amundsen Sea Low, which has a significant impact on regional sea-ice extent. The decrease in accumulation rates at Roosevelt Island may therefore be explained in terms of a recent strengthening of the ASL and the expansion of sea ice in the eastern Ross Sea. The start of the rapid decrease in RICE accumulation rates observed in 1965 CE may thus mark the onset of significant increases in regional sea-ice extent.

Response to Comment on “Atmospheric Mercury Accumulation Rates between 5900 and 800 Calibrated Years BP in the High Arctic of Canada Recorded by Peat Hummocks”

2005 ◽  
Vol 39 (3) ◽  
pp. 910-912 ◽  
Author(s):  
William Shotyk ◽  
Nicolas Givelet ◽  
Andriy K. Cheburkin ◽  
Michael E. Goodsite ◽  
Fiona Roos-Barraclough
Keyword(s):  
High Arctic ◽  
Atmospheric Mercury ◽  
Mercury Accumulation ◽  
Accumulation Rates

Charcoal records from thermokarst deposits in central Yakutia, eastern Siberia: Implications for forest fire history and thermokarst development

2009 ◽  
Vol 71 (1) ◽  
pp. 36-40 ◽  
Author(s):  
Fumitaka Katamura ◽  
Masami Fukuda ◽  
Nikolai Petrovich Bosikov ◽  
Roman Vasilievich Desyatkin
Keyword(s):  
Forest Fires ◽  
Fire History ◽  
Fire Regime ◽  
Accumulation Rate ◽  
Eastern Siberia ◽  
Accumulation Rates ◽  
High Accumulation ◽  
Thermokarst Lake ◽  
Central Yakutia ◽  
Pollen Accumulation Rates

AbstractMacroscopic charcoal records from a thermokarst lake deposit in central Yakutia, eastern Siberia, were used to reconstruct the history of forest fires and investigate its relationship to thermokarst initiation. High accumulation rates of charcoal and pollen were coincident in the basal deposits of the thermokarst lake, which suggests that both were initially deposited on the forest floor and subsequently reworked and accumulated in the thermokarst depression. High charcoal and pollen accumulation rates in the basal deposits, dating to 11,000–9000 cal yr BP, also indicate that the thermokarst topography developed during the early Holocene. A lower charcoal accumulation rate after ca. 9000 cal yr BP suggests that thermokarst development has been inhibited since this time. It also indicates that a surface-fire regime has been predominant at least since ca. 9000 cal yr BP in central Yakutia.

China, the UN, and Human Protection

2020 ◽  
Author(s):  
Rosemary Foot
Keyword(s):  
United Nations ◽  
Public Goods ◽  
World Order ◽  
Active Engagement ◽  
Fair Share ◽  
Global Order ◽  
The Core ◽  
Short Period ◽  
The Future ◽  
The United Nations

Over a relatively short period of time, Beijing moved from passive involvement with the UN to active engagement. How are we to make sense of the People’s Republic of China’s (PRC) embrace of the UN, and what does its engagement mean in larger terms? Is it a ‘supporter’ that takes its fair share of responsibilities, or a ‘spoiler’ that seeks to transform the UN’s contribution to world order? Certainly, it is difficult to label it a ‘shirker’ in the last decade or more, given Beijing’s apparent appreciation of the UN, its provision of public goods to the organization, and its stated desire to offer ‘Chinese wisdom and a Chinese approach to solving the problems facing mankind’. This study traces questions such as these, interrogating the value of such categorization through direct focus on Beijing’s involvement in one of the most contentious areas of UN activity—human protection—contentious because the norm of human protection tips the balance away from the UN’s Westphalian state-based profile, towards the provision of greater protection for the security of individuals and their individual liberties. The argument that follows shows that, as an ever-more crucial actor within the United Nations, Beijing’s rhetoric and some of its practices are playing an increasingly important role in determining how this norm is articulated and interpreted. In some cases, the PRC is also influencing how these ideas of human protection are implemented. At stake in the questions this book tackles is both how we understand the PRC as a participant in shaping global order, and the future of some of the core norms that constitute global order.

scholarly journals Small-scale spatio-temporal characteristics of accumulation rates in western Dronning Maud Land, Antarctica

2008 ◽  
Vol 54 (185) ◽  
pp. 315-323 ◽  
Author(s):  
Helgard Anschütz ◽  
Daniel Steinhage ◽  
Olaf Eisen ◽  
Hans Oerter ◽  
Martin Horwath ◽  
...  
Keyword(s):  
Accumulation Rate ◽  
Temporal Variations ◽  
Spatial Variations ◽  
Small Scale ◽  
Accumulation Rates ◽  
Order Of Magnitude ◽  
Dronning Maud Land ◽  
Spatio Temporal ◽  
Ground Penetrating ◽  
Firn Core

AbstractSpatio-temporal variations of the recently determined accumulation rate are investigated using ground-penetrating radar (GPR) measurements and firn-core studies. The study area is located on Ritscherflya in western Dronning Maud Land, Antarctica, at an elevation range 1400–1560 m. Accumulation rates are derived from internal reflection horizons (IRHs), tracked with GPR, which are connected to a dated firn core. GPR-derived internal layer depths show small relief along a 22 km profile on an ice flowline. Average accumulation rates are about 190 kg m−2 a−1 (1980–2005) with spatial variability (1σ) of 5% along the GPR profile. The interannual variability obtained from four dated firn cores is one order of magnitude higher, showing 1σ standard deviations around 30%. Mean temporal variations of GPRderived accumulation rates are of the same magnitude or even higher than spatial variations. Temporal differences between 1980–90 and 1990–2005, obtained from two dated IRHs along the GPR profile, indicate temporally non-stationary processes, linked to spatial variations. Comparison with similarly obtained accumulation data from another coastal area in central Dronning Maud Land confirms this observation. Our results contribute to understanding spatio-temporal variations of the accumulation processes, necessary for the validation of satellite data (e.g. altimetry studies and gravity missions such as Gravity Recovery and Climate Experiment (GRACE)).

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