| 1. |
- Loisel, Julie, et al.
(författare)
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A database and synthesis of northern peatland soil properties and Holocene carbon and nitrogen accumulation
- 2014
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Ingår i: The Holocene. - : SAGE Publications. - 0959-6836 .- 1477-0911. ; 24:9, s. 1028-1042
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Tidskriftsartikel (refereegranskat)abstract
- Here, we present results from the most comprehensive compilation of Holocene peat soil properties with associated carbon and nitrogen accumulation rates for northern peatlands. Our database consists of 268 peat cores from 215 sites located north of 45 degrees N. It encompasses regions within which peat carbon data have only recently become available, such as the West Siberia Lowlands, the Hudson Bay Lowlands, Kamchatka in Far East Russia, and the Tibetan Plateau. For all northern peatlands, carbon content in organic matter was estimated at 42 +/- 3% (standard deviation) for Sphagnum peat, 51 +/- 2% for non-Sphagnum peat, and at 49 +/- 2% overall. Dry bulk density averaged 0.12 +/- 0.07 g/cm(3), organic matter bulk density averaged 0.11 +/- 0.05 g/cm(3), and total carbon content in peat averaged 47 +/- 6%. In general, large differences were found between Sphagnum and non-Sphagnum peat types in terms of peat properties. Time-weighted peat carbon accumulation rates averaged 23 +/- 2 (standard error of mean) g C/m(2)/yr during the Holocene on the basis of 151 peat cores from 127 sites, with the highest rates of carbon accumulation (25-28 g C/m(2)/yr) recorded during the early Holocene when the climate was warmer than the present. Furthermore, we estimate the northern peatland carbon and nitrogen pools at 436 and 10 gigatons, respectively. The database is publicly available at https://peatlands.lehigh.edu.
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| 2. |
- Xing, Shan, et al.
(författare)
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Iodine-129 in Snow and Seawater in the Antarctic : Level and Source
- 2015
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Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 49:11, s. 6691-6700
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Tidskriftsartikel (refereegranskat)abstract
- Anthropogenic I-129 has been released to the environment in different ways and chemical species by human nuclear activities since the 1940s. These sources provide ideal tools to trace the dispersion of volatile pollutants in the atmosphere. Snow and seawater samples collected in Bellingshausen, Amundsen, and Ross Seas in Antarctica in 2011 were analyzed for I-129 and I-127, including organic forms; it was observed that I-129/I-127 atomic ratios in the Antarctic surface seawater ((6.1-13) x 10(-12)) are about 2 orders of magnitude lower than those in the Antarctic snow ((6.8-9.5) x 10(-1)0), but 4-6 times higher than the prenuclear level (1.5 x 10(-12)), indicating a predominantly anthropogenic source of I-129 in the Antarctic environment. The I-129 level in snow in Antarctica is 24 orders of magnitude lower than that in the Northern Hemisphere, but is not significantly higher than that observed in other sites in the Southern Hemisphere. This feature indicates that I-129 in Antarctic snow mainly originates from atmospheric nuclear weapons testing from 1945 to 1980; resuspension and re-emission of the fallout I-129 in the Southern Hemisphere maintains the I-129 level in the Antarctic atmosphere. I-129 directly released to the atmosphere and re-emitted marine discharged I-129 from reprocessing plants in Europe might not significantly disperse to Antarctica.
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| 3. |
- Xing, Shan, et al.
(författare)
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Water Circulation and Marine Environment in the Antarctic Traced by Speciation of I-129 and I-127
- 2017
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Ingår i: Scientific Reports. - : Nature Publishing Group. - 2045-2322. ; 7
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Tidskriftsartikel (refereegranskat)abstract
- Emissions of anthropogenic I-129 from human nuclear activities are now detected in the surface water of the Antarctic seas. Surface seawater samples from the Drake Passage, Bellingshausen, Amundsen, and Ross Seas were analyzed for total I-129 and I-127, as well as for iodide and iodate of these two isotopes. The variability of I-127 and I-129 concentrations and their species (I-127(-)/(IO3-)-I-127, I-129(-)/(IO3-)-I-129) suggest limited environmental impact where ((1.15-3.15) x 10(6) atoms/L for I-129 concentration and (0.61-1.98) x 10(-11) for I-129/I-127 atomic ratios are the lowest ones compared to the other oceans. The iodine distribution patterns provide useful information on surface water transport and mixing that are vital for better understanding of the Southern Oceans effects on the global climate change. The results indicate multiple spatial interactions between the Antarctic Circumpolar Current (ACC) and Antarctic Peninsula Coastal Current (APCC). These interactions happen in restricted circulation pathways that may partly relate to glacial melting and icebergs transport. Biological activity during the warm season should be one of the key factors controlling the reduction of iodate in the coastal water in the Antarctic.
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| 4. |
- Yi, Peng, et al.
(författare)
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Late Holocene pathway of Asian Summer Monsoons imprinted in soils and societal implications
- 2019
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Ingår i: Quaternary Science Reviews. - : Elsevier. - 0277-3791 .- 1873-457X. ; 215, s. 35-44
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Tidskriftsartikel (refereegranskat)abstract
- The Asian Summer Monsoons (ASM) represent the main source of precipitation in China and East Asia with about one third of the world population and a region of widespread civilizations. Identifying the temporal and spatial patterns (pathways) of these monsoonal events during the Late Holocene to today has been a matter of debate amongst the scientific community. Here we show that the distribution patterns of the cosmogenic isotope Be-10 and oceanic I-127 in the topsoil across China exhibit imprints of the main ASM pathways. Our results indicate the monsoon pathway pattern persisted for several millennia or more and suggest a strong bond between Be-10 and water vapor transport patterns. Our data also reveal a(127)I distribution pattern controlled by the ASM pathways, rather than proximity to the sea or bedrock weathering. The persistent pathway of the ASM during the late Holocene, together with higher than average global soil iodine concentration, may have further strengthened the development of civilizations in this region of the world through reduction of iodine deficiency related diseases. (C) 2019 Elsevier Ltd. All rights reserved.
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