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Berner LT, Orndahl KM, Rose M, Tamstorf M, Arndal MF, Alexander HD, Humphreys ER, Loranty MM, Ludwig SM, Nyman J, Juutinen S, Aurela M, Happonen K, Mikola J, Mack MC, Vankoughnett MR, Iversen CM, Salmon VG, Yang D, Kumar J, Grogan P, Danby RK, Scott NA, Olofsson J, Siewert MB, Deschamps L, Lévesque E, Maire V, Morneault A, Gauthier G, Gignac C, Boudreau S, Gaspard A, Kholodov A, Bret-Harte MS, Greaves HE, Walker D, Gregory FM, Michelsen A, Kumpula T, Villoslada M, Ylänne H, Luoto M, Virtanen T, Forbes BC, Hölzel N, Epstein H, Heim RJ, Bunn A, Holmes RM, Hung JKY, Natali SM, Virkkala AM, Goetz SJ. The Arctic Plant Aboveground Biomass Synthesis Dataset. Sci Data 2024; 11:305. [PMID: 38509110 PMCID: PMC10954756 DOI: 10.1038/s41597-024-03139-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Accepted: 03/14/2024] [Indexed: 03/22/2024] Open
Abstract
Plant biomass is a fundamental ecosystem attribute that is sensitive to rapid climatic changes occurring in the Arctic. Nevertheless, measuring plant biomass in the Arctic is logistically challenging and resource intensive. Lack of accessible field data hinders efforts to understand the amount, composition, distribution, and changes in plant biomass in these northern ecosystems. Here, we present The Arctic plant aboveground biomass synthesis dataset, which includes field measurements of lichen, bryophyte, herb, shrub, and/or tree aboveground biomass (g m-2) on 2,327 sample plots from 636 field sites in seven countries. We created the synthesis dataset by assembling and harmonizing 32 individual datasets. Aboveground biomass was primarily quantified by harvesting sample plots during mid- to late-summer, though tree and often tall shrub biomass were quantified using surveys and allometric models. Each biomass measurement is associated with metadata including sample date, location, method, data source, and other information. This unique dataset can be leveraged to monitor, map, and model plant biomass across the rapidly warming Arctic.
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Affiliation(s)
- Logan T Berner
- School of Informatics, Computing, and Cyber Systems, Northern Arizona University, Flagstaff, USA.
| | - Kathleen M Orndahl
- School of Informatics, Computing, and Cyber Systems, Northern Arizona University, Flagstaff, USA
| | - Melissa Rose
- School of Informatics, Computing, and Cyber Systems, Northern Arizona University, Flagstaff, USA
| | - Mikkel Tamstorf
- Department of Ecoscience, Aarhus University, Aarhus, Denmark
| | - Marie F Arndal
- Department of Ecoscience, Aarhus University, Aarhus, Denmark
| | - Heather D Alexander
- College of Forestry, Wildlife, and Environment, Auburn University, Auburn, USA
| | - Elyn R Humphreys
- Department of Geography and Environmental Studies, Carleton University, Ottawa, Canada
| | | | - Sarah M Ludwig
- Department of Earth and Environmental Sciences, Columbia University, Palisades, USA
| | - Johanna Nyman
- Jeb E. Brooks School of Public Policy, Cornell University, Ithaca, USA
| | - Sari Juutinen
- Climate System Research, Finnish Meteorological Institute, Helsinki, Finland
| | - Mika Aurela
- Finnish Meteorological Institute, Helsinki, Finland
| | | | - Juha Mikola
- Bioeconomy and Environment Unit, Natural Resources Institute Finland, Helsinki, Finland
| | - Michelle C Mack
- Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, USA
- Department of Biological Sciences, Northern Arizona University, Flagstaff, USA
| | | | - Colleen M Iversen
- Climate Change Science Institute, Oak Ridge National Laboratory, Oak Ridge, USA
| | - Verity G Salmon
- Climate Change Science Institute, Oak Ridge National Laboratory, Oak Ridge, USA
- Environmental Science Division, Oak Ridge National Laboratory, Oak Ridge, USA
| | - Dedi Yang
- Environmental Science Division, Oak Ridge National Laboratory, Oak Ridge, USA
| | - Jitendra Kumar
- Environmental Science Division, Oak Ridge National Laboratory, Oak Ridge, USA
| | - Paul Grogan
- Department of Biology, Queen's University, Kingston, Canada
| | - Ryan K Danby
- Department of Geography and Planning, Queen's University, Kingston, Canada
| | - Neal A Scott
- Department of Geography and Planning, Queen's University, Kingston, Canada
| | - Johan Olofsson
- Department of Ecology and Environmental Science, Umeå University, Umeå, Sweden
| | - Matthias B Siewert
- Department of Ecology and Environmental Science, Umeå University, Umeå, Sweden
| | - Lucas Deschamps
- Département des sciences de l'environnement, Université du Québec à Trois-Rivières, Trois-Rivières, Canada
| | - Esther Lévesque
- Département des sciences de l'environnement, Université du Québec à Trois-Rivières, Trois-Rivières, Canada
| | - Vincent Maire
- Département des sciences de l'environnement, Université du Québec à Trois-Rivières, Trois-Rivières, Canada
| | - Amélie Morneault
- Département des sciences de l'environnement, Université du Québec à Trois-Rivières, Trois-Rivières, Canada
| | - Gilles Gauthier
- Centre d'Études Nordiques, Université Laval, Québec, Canada
- Department of Biology, Université Laval, Québec, Canada
| | - Charles Gignac
- Centre d'Études Nordiques, Université Laval, Québec, Canada
- Department of Plant Science, Université Laval, Québec, Canada
| | | | - Anna Gaspard
- Department of Biology, Université Laval, Québec, Canada
| | | | | | - Heather E Greaves
- Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, USA
| | - Donald Walker
- Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, USA
| | - Fiona M Gregory
- Alberta Biodiversity Monitoring Institute, University of Alberta, Edmonton, Canada
| | - Anders Michelsen
- Department of Biology, University of Copenhagen, København, Denmark
| | - Timo Kumpula
- Department of Geographical and Historical Studies, University of Eastern Finland, Joensuu, Finland
| | - Miguel Villoslada
- Department of Geographical and Historical Studies, University of Eastern Finland, Joensuu, Finland
- Institute of Agriculture and Environmental Sciences, Estonian University of Life Sciences, Tartu, Estonia
| | - Henni Ylänne
- School of Forest Sciences, University of Eastern Finland, Joensuu, Finland
| | - Miska Luoto
- Department of Geosciences and Geography, University of Helsinki, Helsinki, Finland
| | - Tarmo Virtanen
- Ecosystems and Environment Research Program, University of Helsinki, Helsinki, Finland
| | - Bruce C Forbes
- Arctic Centre, University of Lapland, Rovaniemi, Finland
| | - Norbert Hölzel
- Institute of Landscape Ecology, University of Münster, Münster, Germany
| | - Howard Epstein
- Department of Environmental Science, University of Virginia, Charlottesville, USA
| | - Ramona J Heim
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Zürich, Switzerland
| | - Andrew Bunn
- Department of Environmental Sciences, Western Washington University, Bellingham, USA
| | | | | | | | | | - Scott J Goetz
- School of Informatics, Computing, and Cyber Systems, Northern Arizona University, Flagstaff, USA
- Bioeconomy and Environment Unit, Natural Resources Institute Finland, Helsinki, Finland
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Zona D, Lafleur PM, Hufkens K, Gioli B, Bailey B, Burba G, Euskirchen ES, Watts JD, Arndt KA, Farina M, Kimball JS, Heimann M, Göckede M, Pallandt M, Christensen TR, Mastepanov M, López‐Blanco E, Dolman AJ, Commane R, Miller CE, Hashemi J, Kutzbach L, Holl D, Boike J, Wille C, Sachs T, Kalhori A, Humphreys ER, Sonnentag O, Meyer G, Gosselin GH, Marsh P, Oechel WC. Pan-Arctic soil moisture control on tundra carbon sequestration and plant productivity. Glob Chang Biol 2023; 29:1267-1281. [PMID: 36353841 PMCID: PMC10099953 DOI: 10.1111/gcb.16487] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Revised: 09/16/2022] [Accepted: 10/05/2022] [Indexed: 05/26/2023]
Abstract
Long-term atmospheric CO2 concentration records have suggested a reduction in the positive effect of warming on high-latitude carbon uptake since the 1990s. A variety of mechanisms have been proposed to explain the reduced net carbon sink of northern ecosystems with increased air temperature, including water stress on vegetation and increased respiration over recent decades. However, the lack of consistent long-term carbon flux and in situ soil moisture data has severely limited our ability to identify the mechanisms responsible for the recent reduced carbon sink strength. In this study, we used a record of nearly 100 site-years of eddy covariance data from 11 continuous permafrost tundra sites distributed across the circumpolar Arctic to test the temperature (expressed as growing degree days, GDD) responses of gross primary production (GPP), net ecosystem exchange (NEE), and ecosystem respiration (ER) at different periods of the summer (early, peak, and late summer) including dominant tundra vegetation classes (graminoids and mosses, and shrubs). We further tested GPP, NEE, and ER relationships with soil moisture and vapor pressure deficit to identify potential moisture limitations on plant productivity and net carbon exchange. Our results show a decrease in GPP with rising GDD during the peak summer (July) for both vegetation classes, and a significant relationship between the peak summer GPP and soil moisture after statistically controlling for GDD in a partial correlation analysis. These results suggest that tundra ecosystems might not benefit from increased temperature as much as suggested by several terrestrial biosphere models, if decreased soil moisture limits the peak summer plant productivity, reducing the ability of these ecosystems to sequester carbon during the summer.
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Affiliation(s)
- Donatella Zona
- Department BiologySan Diego State UniversitySan DiegoCaliforniaUSA
- School of BiosciencesUniversity of SheffieldSheffieldUK
| | - Peter M. Lafleur
- School of the EnvironmentTrent UniversityPeterboroughOntarioCanada
| | | | - Beniamino Gioli
- National Research Council (CNR)Institute of BioEconomy (IBE)FlorenceItaly
| | - Barbara Bailey
- Department of Mathematics and Statistics, San Diego State UniversitySan DiegoCaliforniaUSA
| | - George Burba
- LI‐COR BiosciencesLincolnNebraskaUSA
- The Robert B. Daugherty Water for Food Global Institute and School of Natural ResourcesUniversity of NebraskaLincolnNebraskaUSA
| | | | - Jennifer D. Watts
- Woodwell Climate Research CenterFalmouthMassachusettsUSA
- W.A. Franke College of Forestry & ConservationThe University of MontanaMissoulaMontanaUSA
| | - Kyle A. Arndt
- Woodwell Climate Research CenterFalmouthMassachusettsUSA
| | - Mary Farina
- Woodwell Climate Research CenterFalmouthMassachusettsUSA
| | - John S. Kimball
- W.A. Franke College of Forestry & ConservationThe University of MontanaMissoulaMontanaUSA
| | - Martin Heimann
- Max Planck Institute for BiogeochemistryJenaGermany
- Faculty of Science, Institute for Atmospheric and Earth System Research (INAR) / Physics, University of HelsinkiHelsinkiFinland
| | | | | | - Torben R. Christensen
- Department of Ecoscience, Arctic Research CentreAarhus UniversityRoskildeDenmark
- Oulanka Research StationOulu UniversityKuusamoFinland
| | - Mikhail Mastepanov
- Department of Ecoscience, Arctic Research CentreAarhus UniversityRoskildeDenmark
- Oulanka Research StationOulu UniversityKuusamoFinland
| | - Efrén López‐Blanco
- Department of Ecoscience, Arctic Research CentreAarhus UniversityRoskildeDenmark
- Department of Environment and Minerals, Greenland Institute of Natural ResourcesNuukGreenland
| | | | - Roisin Commane
- Department of Earth and Environmental Sciences, Lamont‐Doherty Earth ObservatoryColumbia UniversityPalisadesNew YorkUSA
| | - Charles E. Miller
- Jet Propulsion LaboratoryCalifornia Institute of TechnologyPasadenaCaliforniaUSA
| | - Josh Hashemi
- Department BiologySan Diego State UniversitySan DiegoCaliforniaUSA
- Environmental Meteorology, Institute of Earth and Environmental SciencesUniversity of FreiburgFreiburgGermany
| | - Lars Kutzbach
- Institute of Soil Science, Center for Earth System Research and Sustainability (CEN)Universität HamburgHamburgGermany
| | - David Holl
- Institute of Soil Science, Center for Earth System Research and Sustainability (CEN)Universität HamburgHamburgGermany
| | - Julia Boike
- Geography DepartmentHumboldt‐Universität zu BerlinBerlinGermany
- Alfred Wegener Institute Helmholtz Centre for Polar and Marine ResearchPotsdamGermany
| | | | - Torsten Sachs
- GFZ German Research Centre for GeosciencesPotsdamGermany
| | - Aram Kalhori
- GFZ German Research Centre for GeosciencesPotsdamGermany
| | - Elyn R. Humphreys
- Department of Geography & Environmental StudiesCarleton UniversityOttawaOntarioCanada
| | - Oliver Sonnentag
- Département de GéographieUniversité de MontréalMontréalQuebecCanada
| | - Gesa Meyer
- Département de GéographieUniversité de MontréalMontréalQuebecCanada
| | | | - Philip Marsh
- Department of Geography and Environmental Studies, Wilfrid Laurier UniversityWaterlooOntarioCanada
| | - Walter C. Oechel
- Department BiologySan Diego State UniversitySan DiegoCaliforniaUSA
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3
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St Louis VL, Graydon JA, Lehnherr I, Amos HM, Sunderland EM, St Pierre KA, Emmerton CA, Sandilands K, Tate M, Steffen A, Humphreys ER. Atmospheric Concentrations and Wet/Dry Loadings of Mercury at the Remote Experimental Lakes Area, Northwestern Ontario, Canada. Environ Sci Technol 2019; 53:8017-8026. [PMID: 31250626 DOI: 10.1021/acs.est.9b01338] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Mercury (Hg) is a global pollutant released from both natural and human sources. Here we compare long-term records of wet deposition loadings of total Hg (THg) in the open to dry deposition loadings of THg in throughfall and litterfall under four boreal mixedwood canopy types at the remote Experimental Lakes Area (ELA) in Northwestern Ontario, Canada. We also present long-term records of atmospheric concentrations of gaseous elemental (GEM), gaseous oxidized (GOM), and particle bound (PBM) Hg measured at the ELA. We show that dry THg loadings in throughfall and litterfall are 2.7 to 6.1 times greater than wet THg loadings in the open. GEM concentrations showed distinct monthly and daily patterns, correlating positively in spring and summer with rates of gross ecosystem productivity and respiration. GOM and PBM concentrations were less variable throughout the year but were highest in the winter, when concentrations of anthropogenically sourced particles and gases were also high. Forest fires, Arctic air masses, and road salt also impacted GEM, GOM, and PBM concentrations at the ELA. A nested GEOS-Chem simulation for the ELA region produced a dry/wet deposition ratio of >5, suggesting that the importance of dry deposition in forested regions can be reasonably modeled by existing schemes for trace gases.
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Affiliation(s)
- Vincent L St Louis
- Department of Biological Sciences , University of Alberta , Edmonton , Alberta T6G 2E9 , Canada
| | - Jennifer A Graydon
- Department of Biological Sciences , University of Alberta , Edmonton , Alberta T6G 2E9 , Canada
| | - Igor Lehnherr
- Department of Geography , University of Toronto-Mississauga , 3359 Mississauga Road , Mississauga , Ontario L5L 1C6 , Canada
| | - Helen M Amos
- Harvard T.H. Chan School of Public Health , Department of Environmental Health , Boston , Massachusetts 02215 , United States
| | - Elsie M Sunderland
- Harvard T.H. Chan School of Public Health , Department of Environmental Health , Boston , Massachusetts 02215 , United States
- Harvard John A. Paulson School of Engineering and Applied Sciences , Cambridge , Massachusetts 02138 , United States
| | - Kyra A St Pierre
- Department of Biological Sciences , University of Alberta , Edmonton , Alberta T6G 2E9 , Canada
| | - Craig A Emmerton
- Department of Biological Sciences , University of Alberta , Edmonton , Alberta T6G 2E9 , Canada
| | - Ken Sandilands
- International Institute of Sustainable Development - Experimental Lakes Area (IISD-ELA) , 111 Lombard Avenue, Suite 325 , Winnipeg , Manitoba R3B 0T4 , Canada
| | - Michael Tate
- University of Wisconsin , Aquatic Science Center , 1975 Willow Drive , Madison , Wisconsin 53706 , United States
| | - Alexandra Steffen
- Environment and Climate Change Canada, Science and Technology Branch , Air Quality Research , 4905 Dufferin Street , Toronto , Ontario M3H 5T4 , Canada
| | - Elyn R Humphreys
- Department of Geography and Environmental Studies , Carleton University , Ottawa , Ontario K1S 5B6 , Canada
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Emmerton CA, St Louis VL, Humphreys ER, Gamon JA, Barker JD, Pastorello GZ. Net ecosystem exchange of CO2 with rapidly changing high Arctic landscapes. Glob Chang Biol 2016; 22:1185-1200. [PMID: 26279166 DOI: 10.1111/gcb.13064] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2015] [Accepted: 07/25/2015] [Indexed: 06/04/2023]
Abstract
High Arctic landscapes are expansive and changing rapidly. However, our understanding of their functional responses and potential to mitigate or enhance anthropogenic climate change is limited by few measurements. We collected eddy covariance measurements to quantify the net ecosystem exchange (NEE) of CO2 with polar semidesert and meadow wetland landscapes at the highest latitude location measured to date (82°N). We coupled these rare data with ground and satellite vegetation production measurements (Normalized Difference Vegetation Index; NDVI) to evaluate the effectiveness of upscaling local to regional NEE. During the growing season, the dry polar semidesert landscape was a near-zero sink of atmospheric CO2 (NEE: -0.3 ± 13.5 g C m(-2) ). A nearby meadow wetland accumulated over 300 times more carbon (NEE: -79.3 ± 20.0 g C m(-2) ) than the polar semidesert landscape, and was similar to meadow wetland NEE at much more southerly latitudes. Polar semidesert NEE was most influenced by moisture, with wetter surface soils resulting in greater soil respiration and CO2 emissions. At the meadow wetland, soil heating enhanced plant growth, which in turn increased CO2 uptake. Our upscaling assessment found that polar semidesert NDVI measured on-site was low (mean: 0.120-0.157) and similar to satellite measurements (mean: 0.155-0.163). However, weak plant growth resulted in poor satellite NDVI-NEE relationships and created challenges for remotely detecting changes in the cycling of carbon on the polar semidesert landscape. The meadow wetland appeared more suitable to assess plant production and NEE via remote sensing; however, high Arctic wetland extent is constrained by topography to small areas that may be difficult to resolve with large satellite pixels. We predict that until summer precipitation and humidity increases enough to offset poor soil moisture retention, climate-related changes to productivity on polar semideserts may be restricted.
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Affiliation(s)
- Craig A Emmerton
- Department of Biological Sciences, University of Alberta, Edmonton, AB, T6G 2E9, Canada
| | - Vincent L St Louis
- Department of Biological Sciences, University of Alberta, Edmonton, AB, T6G 2E9, Canada
| | - Elyn R Humphreys
- Department of Geography and Environmental Studies, Carleton University, Ottawa, ON, K1S 5B6, Canada
| | - John A Gamon
- Department of Biological Sciences, University of Alberta, Edmonton, AB, T6G 2E9, Canada
- Department of Earth & Atmospheric Sciences, University of Alberta, Edmonton, AB, T6G 2E3, Canada
| | - Joel D Barker
- School of Earth Sciences, Ohio State University, Marion, OH, 43210, USA
| | - Gilberto Z Pastorello
- Computational Research Division, Lawrence Berkeley National Lab, Berkeley, CA, 94720-8150, USA
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Lafleur PM, Humphreys ER, St Louis VL, Myklebust MC, Papakyriakou T, Poissant L, Barker JD, Pilote M, Swystun KA. Variation in peak growing season net ecosystem production across the Canadian Arctic. Environ Sci Technol 2012; 46:7971-7977. [PMID: 22779925 DOI: 10.1021/es300500m] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Tundra ecosystems store vast amounts of soil organic carbon, which may be sensitive to climatic change. Net ecosystem production, NEP, is the net exchange of carbon dioxide (CO(2)) between landscapes and the atmosphere, and represents the balance between CO(2) uptake by photosynthesis and release by decomposition and autotrophic respiration. Here we examine CO(2) exchange across seven sites in the Canadian low and high Arctic during the peak growing season (July) in summer 2008. All sites were net sinks for atmospheric CO(2) (NEP ranged from 5 to 67 g C m(-2)), with low Arctic sites being substantially larger CO(2) sinks. The spatial difference in NEP between low and high Arctic sites was determined more by CO(2) uptake via gross ecosystem production than by CO(2) release via ecosystem respiration. Maximum gross ecosystem production at the low Arctic sites (average 8.6 μmol m(-2) s(-1)) was about 4 times larger than for high Arctic sites (average 2.4 μmol m(-2) s(-1)). NEP decreased with increasing temperature at all low Arctic sites, driven largely by the ecosystem respiration response. No consistent temperature response was found for the high Arctic sites. The results of this study clearly indicate there are large differences in tundra CO(2) exchange between high and low Arctic environments and this difference should be a central consideration in studies of Arctic carbon balance and climate change.
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Affiliation(s)
- Peter M Lafleur
- Department of Geography, Trent University , Peterborough, Ontario K9J 7B8, Canada.
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Dimitrov DD, Grant RF, Lafleur PM, Humphreys ER. Modeling the effects of hydrology on gross primary productivity and net ecosystem productivity at Mer Bleue bog. ACTA ACUST UNITED AC 2011. [DOI: 10.1029/2010jg001586] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Dimitrov DD, Grant RF, Lafleur PM, Humphreys ER. Modeling the effects of hydrology on ecosystem respiration at Mer Bleue bog. ACTA ACUST UNITED AC 2010. [DOI: 10.1029/2010jg001312] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Loranty MM, Goetz SJ, Rastetter EB, Rocha AV, Shaver GR, Humphreys ER, Lafleur PM. Scaling an Instantaneous Model of Tundra NEE to the Arctic Landscape. Ecosystems 2010. [DOI: 10.1007/s10021-010-9396-4] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Mason TM, Lord BI, Molineux G, Humphreys ER. Alpha-irradiation of Haemopoietic Tissue in Pre- and Postnatal Mice: 2. Effects of Mid-term Contamination with239Puin Utero. Int J Radiat Biol 2009; 61:393-403. [PMID: 1347073 DOI: 10.1080/09553009214551091] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
The distribution of 239Pu in various tissues of foetal and postnatal offspring of pregnant mice, injected i.v. at 13 days gestation with 30 kBq 239Pu/kg (in some cases with 10 or 100 kBq/kg), together with the numbers of haemopoietic progenitors in the bone marrow, spleen and liver, were measured through to 1 year post-partum. The quality of the haemopoietic microenvironment in these mice was also measured using the renal-capsule implant method. The largest radiation dose received by any haemopoietic organ was that in the liver, amounting to 10-14 mGy, as reported previously. In spite of normal numbers of haemopoietic spleen colony-forming cells (CFC-S) in the liver and seeding, at birth, into the bone marrow where the level of plutonium was minimal, a long-term deficit in their number rapidly developed. The development of the stromal microenvironment, however, was also deficient, suggesting that the dose of alpha-irradiation to the foetal liver was sufficient to cause sublethal damage in those cells destined to become the precursors of the supportive haemopoietic microenvironment in bone marrow and spleen. The results of this study suggest that although the placenta affords significant shielding to the tissues of the developing foetus from maternal contamination, the long-term effects on haemopoiesis are comparable to those in mice contaminated as adults. This further implies that the developing haemopoietic tissues are exquisitely sensitive to 239Pu contamination.
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Affiliation(s)
- T M Mason
- CRC Department of Experimental Haematology, Paterson Institute for Cancer Research, Christie Hospital NHS Trust, Manchester, UK
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Grant RF, Black TA, Humphreys ER, Morgenstern K. Changes in net ecosystem productivity with forest age following clearcutting of a coastal Douglas-fir forest: testing a mathematical model with eddy covariance measurements along a forest chronosequence. Tree Physiol 2007; 27:115-31. [PMID: 17169913 DOI: 10.1093/treephys/27.1.115] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
We hypothesized that changes in net ecosystem productivity (NEP) during aging of coastal Douglas-fir (Pseudotsuga menziesii Mirb. Franco) stands could be explained by (1) changing nutrient uptake caused by different time scales for decomposition of fine, non-woody and coarse woody litter left after harvesting, (2) declines in canopy water status with lengthening of the water uptake pathway during bole and branch growth, and (3) increases in the ratio of autotrophic respiration (R (a)) to gross primary productivity (GPP) with phytomass accumulation. These hypotheses were implemented and tested in the mathematical model ecosys against eddy covariance (EC) measurements of forest CO(2) and energy exchange in a post-clearcut Douglas-fir chronosequence. Hypothesis 1 explained how (a) an initial rise in GPP observed during the first 3 years after clearcutting could be caused by nutrient mineralization from rapid decomposition of fine, non-woody litter with lower C:N ratios (assart effect), (b) a slower rise in GPP during the next 20 years could be caused by immobilization during later decomposition of coarse woody litter, and (c) a rapid rise in GPP between 20 and 40 years after clearcutting could be caused by nutrient mineralization with further decomposition of coarse woody litter and of its decomposition products. During periods (a) and (b), heterotrophic respiration (R (h)) from decomposition of fine and coarse litter greatly exceeded net primary productivity (NPP = GPP - R (a)) so that Douglas-fir stands were large sources of CO(2). During period (c), NPP exceeded R (h) so that these stands became large sinks for CO(2). Hypothesis 2 explained how declines in NPP during later growth in period (c) could be caused by lower hydraulic conductances in taller trees that would force lower canopy water potentials and hence greater sensitivity of stomatal conductances and CO(2) uptake to vapor pressure deficits. Enhanced sensitivity to vapor pressure deficits was also apparent in the EC measurements over the post-clearcut chronosequence. Hypothesis 3 did not contribute to the explanation of forest age effects on NEP.
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Affiliation(s)
- R F Grant
- Department of Renewable Resources, University of Alberta, Edmonton, AB, Canada T6G 2E3.
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Humphreys ER, Lafleur PM, Flanagan LB, Hedstrom N, Syed KH, Glenn AJ, Granger R. Summer carbon dioxide and water vapor fluxes across a range of northern peatlands. ACTA ACUST UNITED AC 2006. [DOI: 10.1029/2005jg000111] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Elyn R. Humphreys
- Department of Geography; Trent University; Peterborough, Ontario Canada
| | - Peter M. Lafleur
- Department of Geography; Trent University; Peterborough, Ontario Canada
| | - Lawrence B. Flanagan
- Department of Biological Sciences; University of Lethbridge; Lethbridge, Alberta Canada
| | - Newell Hedstrom
- National Water Research Institute, National Hydrology Research Centre; Environment Canada; Saskatoon, Saskatchewan Canada
| | - Kamran H. Syed
- Department of Biological Sciences; University of Lethbridge; Lethbridge, Alberta Canada
| | - Aaron J. Glenn
- Department of Biological Sciences; University of Lethbridge; Lethbridge, Alberta Canada
| | - Raoul Granger
- National Water Research Institute, National Hydrology Research Centre; Environment Canada; Saskatoon, Saskatchewan Canada
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Gaitán S, Tejero C, Humphreys ER, Lord BI. A relationship between residual stromal damage in hematopoietic tissue and the functional activity of granulocytes. Exp Hematol 1993; 21:1227-32. [PMID: 7687218] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
This paper analyzes the function of mouse granulocytes in the long term, after external irradiation with x- and gamma-rays and 239Pu contamination at different gestational ages and in a variety of culture conditions. These treatments can produce persistent defects in the stroma, which regulates hematopoiesis. Superoxide-anion production has been measured in granulocytes from peripheral blood and from long-term bone marrow cultures (LTBMC). A significant enhancement of O2- is produced using single or fractionated doses of x-rays; however, little or no increase is observed with gamma-rays. With 239Pu, enhancement of O2- depends on gestational age at contamination. The absence of hydrocortisone (HC) in LTBMC and the irradiation of the adherent layer with 15 Gy stimulate O2- production. The increased production of O2- appears to be correlated with an excess of colony-stimulating factors (CSFs) released to the supernatant by stromal cells. Neutralization with anti-granulocyte-macrophage CSF (anti-GM-CSF) monoclonal antibody shows that GM-CSF is the main factor produced. In summary, conditions that lead to residual stromal damage also result in the generation of granulocytes that are functionally primed for excess superoxide-anion production.
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Affiliation(s)
- S Gaitán
- Departamento de Bioquímica y Biología Molecular IV, Facultad de Veterinaria, Universidad Complutense de Madrid, Spain
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Abstract
Four groups of 400 12-week-old CBA/H mice were injected i.p. with 69, 139, 280 and 550 Bqg-1 224Ra. A further group of 400 mice were injected i.p. with diluting solution only. The mice were then allowed unrestricted access to food and water until they died or were killed. 53 cases of myeloid leukaemia and 22 cases of osteosarcoma were confirmed in the 2000 mice injected, and for both tumour types direct relationships were shown to exist between the amount of 224Ra administered and the incidence of tumours. It is concluded that mouse is at a greater risk from myeloid leukaemia than from osteosarcoma in the region of administered 224Ra below that which causes a maximum yield of osteosarcoma. These results are discussed in the light of the present acceptance of osteosarcoma as the major risk to man from bone-seeking alpha-particle emitters.
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Lord BI, Humphreys ER, Mason TM. Effects of maternal plutonium contamination on the development of haemopoiesis in the offspring. Int J Radiat Biol 1991; 60:560-1. [PMID: 1679099] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- B I Lord
- Paterson Institute for Cancer Research, Christie Hospital and Holt Radium Institute, Manchester, UK
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Mason TM, Humphreys ER, Lord BI. Alpha-particle irradiation of haemopoietic tissue in pre- and postnatal mice. 1: Distribution of plutonium-239 after mid-term contamination. Int J Radiat Biol 1991; 59:467-78. [PMID: 1671696 DOI: 10.1080/09553009114550421] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Pregnant mice (at 13 days gestation) and age-matched controls were injected with 30 kBq 239Pu/kg and the distribution of plutonium in maternal and foetal tissues measured. Approximately 2% of the activity injected into the mother reached each foetus in 24 h, 95% of which was contained in membranes and placenta. The concentration of plutonium in foetal liver was 3 times the average foetal body concentration; both liver and body concentrations in the foetus increased by the end of gestation. Each pup accumulated only 0.01% extra injected activity after 9 days lactation and, as the resulting concentrations in the neonatal skeleton were low, we conclude that the greatest haemopoietic risk to the offspring from mid-term contamination in utero is in the foetal liver (which received an average dose of 10-14 mGy between the time of mid-term contamination and birth). By the end of gestation about one-quarter of the original activity was transferred to foetal tissues from the maternal liver and skeleton. No significant changes in maternal distribution were detected as a result of lactation. The results of this study are discussed, along with a compilation of previously published data.
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Affiliation(s)
- T M Mason
- Cancer Research Campaign Department of Experimental Haematology, Peterson Institute for Cancer Research, Withington, Manchester, UK
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Lord BI, Molineux G, Humphreys ER, Stones VA. Long-term effects of plutonium-239 and radium-224 on the distribution and performance of pluripotent haemopoietic progenitor cells and their regulatory microenvironment. Int J Radiat Biol 1991; 59:211-27. [PMID: 1671068 DOI: 10.1080/09553009114550191] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Experiments are described which investigate the long-term damage to haemopoietic progenitor cells (CFU-S) and their microenvironment in mouse marrow resulting from the administration of leukaemogenic amounts of plutonium-239 and radium-224. 239Pu (35 Bq g-1 body weight) and 224Ra (555 Bg g-1 body weight) were injected into 10-12-week-old mice, and numbers, proliferative activity and self-renewal capacity of CFU-S were measured at different locations in femoral marrow at intervals over the following 2 years. Parallel measurements were also made of the quality of the haemopoietic microenvironment by ectopic transplantation of bone marrow cells. There was some recovery from the initial effects of 239Pu on CFU-S numbers after 3-6 months, although the recovery was not maintained in all marrow fractions. Following 224Ra administration there was an initial transient increase in CFU-S numbers in the fraction of marrow furthest from bone surfaces but a considerable depression in numbers in other regions of marrow; there was no recovery between 3 and 6 months and subsequent recovery was not complete in all regions of marrow. The differential responses of CFU-S and the haemopoietic microenvironment following 224Ra or 239Pu administration seemed in some ways related to the metabolism of the radionuclides. There was a profound reduction in the ability of marrow to generate ossicles when transplanted under the kidney capsule as a result of the administration of either 224Ra or 239Pu, with only transient recoveries from the effects of 239Pu at 4 days and at 3 months after injection.
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Affiliation(s)
- B I Lord
- Department of Experimental Haematology, Paterson Institute for Cancer Research, Christie Hospital, Manchester, UK
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Humphreys ER, Major RI, Stones VA. The effects of protracted administration of alpha-particle-emitting radionuclides on mice. Int J Radiat Biol 1990; 58:874-6. [PMID: 1977833] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
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Lord BI, Molineux G, Schofield R, Humphreys ER, Stones VA. On the late seeding of CFU-S to the spleen: 8- vs 12-day CFU-S. Exp Hematol 1989; 17:836-42. [PMID: 2666146] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Marrow from 5-fluorouracil- or cyclophosphamide-treated mice, injected into lethally irradiated recipients, gives an increasing number of spleen colonies between days 7 and 14. It has been suggested that the later-forming colonies result from the more primitive spleen colony-forming units (CFU-S), which first seed into the marrow, only later to be recirculated and form colonies in the spleen. Strontium 89 (89Sr), a bone-seeking radionuclide, was injected into recipient mice to block such putative recirculation. A dose of 89Sr, which killed at least 99.8% of CFU-S in, or entering, the bone cavities, was incapable of preventing the increase in spleen colony numbers. Similarly, the splenic environment, modified by the presence of spleen colonies and able to provide a better bed for trapping CFU-S from the peripheral circulation, yielded the same number of further CFU-S, whether or not the animal had received 89Sr. Thus, it was concluded that the 12-day CFU-S does not seed initially into the marrow spaces. Direct observation of the quality of CFU-S initially seeding into the bone marrow and spleen showed, by retransplantation into secondary irradiated mice, that a similar spectrum of CFU-S types had seeded both organs.
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Affiliation(s)
- B I Lord
- Paterson Institute for Cancer Research, Christie Hospital, Manchester, UK
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Humphreys ER, Loutit JF, Stones VA. The induction by 239Pu of myeloid leukaemia and osteosarcoma in female CBA mice. Int J Radiat Biol Relat Stud Phys Chem Med 1987; 51:331-9. [PMID: 3493993 DOI: 10.1080/09553008714550801] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Plutonium-239 was injected into 12-week-old female CBA/H mice in the range 1.85-18.5 kBq kg-1 either as a single injection or as 16 injections spaced at 3.5 day intervals over eight weeks. There was a highly significant increase in the yield of fully developed osteosarcomas with increased amounts of 239Pu for both modes of injection. Osteosarcomas too small to be diagnosed radiographically were also seen in many bones and small but significant yields of myeloid leukaemia were seen in animals given plutonium. Although more myeloid leukaemia was seen in the mice given plutonium in divided amounts than in those given the plutonium in a single injection it could not be shown that multiple injection significantly affected the yield of either late effect.
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Abstract
Calculations are described, based on experimental findings, which show the variation of absorbed dose from 224Ra in bone marrow of CBA/H mice. These calculations indicate that, following an injection of a leukaemogenic amount of 16 kBq 224Ra into these mice, most marrow cells in the cancellous bone of femur ends are killed but most marrow cells in the femur shaft survive. The calculations also suggest that the mean leukaemogenic absorbed dose of about 1.5 Gy is received by a population of marrow cells about 30 microns from bone surface in the femur shaft.
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Schofield R, Lord BI, Humphreys ER, Stones VA. Effects of plutonium-239 on haemopoiesis. I. Quantitative and qualitative changes in CFU-S in different regions of the mouse femur and vertebrae. Int J Radiat Biol Relat Stud Phys Chem Med 1986; 49:1021-9. [PMID: 3486845 DOI: 10.1080/09553008514553241] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Mice were injected with plutonium-239 (960 Bq/mouse) and, over a period of four months, the response of haemopoietic tissue and the self-renewal capacity of its stem cells was monitored. Cellularity, CFU-S concentration and self-renewal capacity were measured in five different regions of bone and marrow--axial and marginal marrow of the femoral shaft, femur shaft, proximal and distal ends of the femur shaft and vertebrae. Cellularities were little affected by plutonium but CFU-S were reduced in all regions, most severely in the bone shaft and marginal marrow due to the initial deposition of plutonium on the bone surface, by four days. The reduction in axial CFU-S, however, was due probably to a relatively long plasma half-life resulting from the tendency of plutonium to combine with plasma proteins. The capacity of CFU-S for self-renewal was reduced and remained low in all zones. Thus, although the highly self-renewing axial CFU-S were depleted, and remained so, due probably to a longer term redistribution of plutonium throughout the marrow, additional proliferation of the more mature CFU-S in the other zones kept their self-renewal low while replenishing their numbers and maintaining a normal cell output.
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Humphreys ER, Loutit JF, Major IR, Stones VA. The induction by 224Ra of myeloid leukaemia and osteosarcoma in male CBA mice. Int J Radiat Biol Relat Stud Phys Chem Med 1985; 47:239-47. [PMID: 3872276] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Radium-224 was injected into 12-week-old male CBA mice in the range 2-64 kBq per mouse either as a single injection or as eight injections spaced at 3.5 day intervals over 4 weeks. Small but significant yields of myeloid leukaemia or osteosarcoma were obtained in all but the control groups. An effect of mode of administration (single or multiple injections) could not be demonstrated but the combined results showed: a maximum yield of myeloid leukaemia in the region 8-16 kBq 224Ra; a greater yield of osteosarcoma than myeloid leukaemia at 64 kBq 224 Ra injected.
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Abstract
A high incidence of incisor abnormalities was found in aged control and aged 224Ra-treated male CBA mice. Visual examination of the abnormalities in both controls and treated mice revealed extreme shortening of the upper incisors and hypoplastic, grooved or undulating enamel. The administration of 865 or 1730 nCi of 224Ra hastened the onset of incisor abnormalities although no specific feature was attributable solely to radium toxicity. Radiography and histology revealed corrugated incisors, obliteration of the pulp cavity, extension and disorganized growth of incisors basally, secondary incisors, open pulp and fractures within the alveoli. There was a statistically-significant reduction in the number of molars present in animals given 432, 865 or 1730 nCi 224Ra.
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Abstract
The rate at which blood is supplied to several bones in female CBA mice was calculated from 18F measurements in bone and blood. Blood flow measurements were compared with plutonium uptake in whole bone and on endosteal and periosteal bone surfaces. The results showed that: (a) the rate at which blood is supplied to bone determines the rate of deposition of plutonium; (b) there is a threshold rate of blood supply below which plutonium is not deposited; and (c) the rate of blood supply determines the density of plutonium deposition on endosteal but not no periosteal bone surfaces. These results are discussed in the light of the current bone blood supply hypotheses.
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Humphreys ER, Stones VA. Mixed ligand chelates and plutonium poisoning. Health Phys 1980; 39:103-105. [PMID: 7419398] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
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Humphreys ER, Stones VA. The relationship between 59Fe uptake in marrow and 239Pu deposition in bone. Int J Radiat Biol Relat Stud Phys Chem Med 1978; 33:571-5. [PMID: 308054 DOI: 10.1080/09553007814550481] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The marrow in the left femur of each of 17 mice was destroyed by X-irradiation and 59Fe and 239Pu uptake into both femurs was measured 1, 3 and 7 days later. Uptake of 59Fe into marrow was depressed in the left femur 1 and 3 days after irradiation but was enhanced in the right unirradiated femur 3 days after the left femur was irradiated. There was no corresponding depression of 239Pu uptake into the left irradiated femur or enhancement into the right unirradiated femur. These results do not support the view that a functioning erythropoietic marrow is necessary for 239Pu to be deposited in bone.
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Humphreys ER, Fisher G, Thorne MC. The measurement of blood flow in mouse femur and its correlation with 239Pu deposition. Calcif Tissue Res 1977; 23:141-5. [PMID: 890551 DOI: 10.1007/bf02012779] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The concentration of 18F was measured in three parts of the femur and in the blood of 36 mice killed at intervals of from 1 min to 2 h after intravenous injection. Blood supply to the bone sections, calculated by dividing the increase in 18F concentration in bone by the integral of 18F concentration in blood between selected time intervals, was shown to be unaffected by the return of 18F from bone to blood at times earlier than 90 min following injection. The supply of blood per unit mass of bone was greatest in distal end of the femur, less in proximal end and least in shaft. In whole femur average blood flow was 230 mm3 per gram fresh bone per min. The deposition of 239Pu in three parts of the mouse femur was shown to be linearly related to blood flow and the nature of the relationship is discussed.
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Searle AG, Beechey CV, Green D, Humphreys ER. Cytogenetic effects of protracted exposures to alpha-particles from plutonium-239 and to gamma-rays from cobalt-60 compared in male mice. Mutat Res 1976; 41:297-310. [PMID: 1012301 DOI: 10.1016/0027-5107(76)90103-2] [Citation(s) in RCA: 33] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Adult C3H X 101 hybrid male mice were injected intravenously with 4 muCi of 239Pu citrate per kg body weight and examined for evidence of cytogenetic damage to the testis after exposures of 21, 28 and 34 weeks, with average doses from alpha-particles estimated as 13, 18 and 18 rad respectively (mean dose rate 0.00006 rad/min). Results were compared with those obtained when equivalent males were exposed continuously and concurrently to 1128 rad 60Co gamma-irradiation over 28 weeks (0.004 rad/min). The following estimates of the relative effectiveness of the alpha- and gamma-radiation were made: 24 for reciprocal translocations and for chromosome fragments, 22 for dominant lethal mutations acting after implantation. These values (with mean of 23) are based on average testis doses, with no correction for probable non-homogeneity of alpha dose distribution. In the mice exposed to gamma-irradiation there were significant reductions in testis mass and epididymal sperm-count. Although corresponding differences from control were not significant in the alpha series, consideration of results from a previous experiment by the same authors [2] allowed the relative effectiveness of the alpha- and gamma-irradiation for testis mass reduction to be estimated as roughly 10-15. Existing data on translocation induction in mouse spermatogonia by low dose-rates of gamma-rays (down to 0.003 rad/min) were analysed. They suggested that minimum rates of induction at very low intensities were not less than 1 X 10(-5) translocations per rad. A comparison of the frequencies of induction of fragments and of sperm-head abnormalities obtained after chronic gamma-ray exposures in the present experiment with those found by other workers after acute X-ray exposures suggested that there were no marked dose-rate effects with these types of mutational effect. Finally, the special problems associated with cytogenetic studies on alpha-emitters are discussed.
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Humphreys ER, Metalli P, Seidel A, Szot Z, Vanderborght O. The distribution of 239Pu in several strains of mice--a collaborative experiment. Int J Appl Radiat Isot 1976; 27:507-13. [PMID: 992885 DOI: 10.1016/0020-708x(76)90081-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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Humphreys ER, Green D. Radiation dose from plutonium deposited in marrow and bone of normal and chimaeric mice. Int J Radiat Biol Relat Stud Phys Chem Med 1975; 27:561-7. [PMID: 1081082 DOI: 10.1080/09553007514550591] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
239Pu citrate was injected intraperitoneally into CBA mice and into CBA mice which had been made chimaeric by replacing their haematopoietic bone-marrow with that from another genetically-identical but cytologically-distinct strain. The mice were killed at three intervals up to 90 days after injection, and the deposited 239Pu was determined radiochemically in bone-marrow and in bone. The average radiation dose (integrated over 90 days) was found to be greater in the bones but lower in the marrow of chimaeric mice than in the corresponding tissues of the normal CBA mice. These results are discussed from the points of view of induction of malignant change in marrow and bone and of plutonium metabolism in the two types of mouse.
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Sutton A, Humphreys ER, Shepherd H, Howells GR. Reduction in the retention of radioactive barium in rats following the addition of sodium alginate derivatives to the diet. Int J Radiat Biol Relat Stud Phys Chem Med 1972; 22:297-300. [PMID: 4538992 DOI: 10.1080/09553007214551081] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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Carr TE, Harrison GE, Humphreys ER, Sutton A. Reduction in the absorption and retention of dietary strontium in man by alginate. Int J Radiat Biol Relat Stud Phys Chem Med 1968; 14:225-33. [PMID: 5303372 DOI: 10.1080/09553006814551031] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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Patrick G, Carr TE, Humphreys ER. Inhibition by alginates of strontium absorption studied in vivo and in vitro. Int J Radiat Biol Relat Stud Phys Chem Med 1967; 12:427-34. [PMID: 5299069 DOI: 10.1080/09553006714551031] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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Abstract
Rats were fed a basic diet supplemented with sodium alginate and with tracer amounts of strontium-85 and calcium-45. Absorption of strontium was always inhibited by the alginate to a greater extent than absorption of calcium. Discrimination against strontium was greatest in alginate containing a high proportion of guluronic acid.
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