126 research outputs found
Residence times and temporal variations of \u3csup\u3e210\u3c/sup\u3ePo in aerosols and precipitation from southeastern Michigan, United States
Daughter products of 222Rn (such as 210Pb, half-life = 22.1 years, and 210Po, half-life = 138 days) have been widely used as tracers to determine the removal rates of aerosols as well to obtain analog information on the behavior of other chemical species in the lower atmosphere. To establish the first data set on the depositional fluxes of 210Po in bulk precipitation and concentrations in air samples from the midwestern United States, we measured the depositional fluxes of 210Pb and 210Po in the bulk (wet plus dry) and dry fallout by deploying a rain collector (dry and bulk) for a period of 17 months. We also collected 30 aerosol samples during this period to assess the temporal variations of these nuclides in the surface air in Detroit, Michigan. The activity of 210Po in the surface air ranged from below detection limit to 0.118 mBq mâ3 (mean of 0.072 mBq mâ3). The specific activities of 210Po and 210Pb in aerosols ranged between 0.28 and 4.48 Bq gâ1 (mean of 0.87 Bq gâ1) and 2.7 and 30 Bq gâ1 (mean of 13.6 Bq gâ1), respectively; these values are about 1â2 orders of magnitude higher than the surface soil. The mean activity ratios of 210Po/210Pb in the bulk precipitation and dry fallout were found to be 0.049 (n = 27) and 0.25 (n = 8), corresponding to residence times of 15 and 75 days, respectively. Higher values in the dry fallout are attributed to resuspension of very fine older material from the ground. The 210Po/210Pb activity ratios in the aerosols varied between 0 and 0.210 (mean of 0.075), with corresponding residence times of 0â61 days (mean of 22 days). The mean deposition velocity and bulk washout ratio obtained using 210Po is compared with those obtained for 210Pb. From the measured aerosol mass concentrations and calculated values of the depositional velocity, the calculated depositional fluxes of aerosols are reported
Radionuclide Data Analysis of Marine Subsistence Food from Amchitka and Adjoining Areas
Derivation of dose estimates from subsistence food such as fish require that the concentrations of radionuclide are precisely known. The safety of subsistence food and the ecosystem in areas adjoining Amchitka requires that the radionuclide concentration of anthropogenic radionuclides, potentially released from the three nuclear tests between 1965 and 1971 at Amchitka Island in the central Aleutian Archipelago, in subsistence food. The total yield of these detonations (6.08 million tons) is estimated to be about 15% of the total yield of all US underground nuclear explosions {Long shot: 80 kton at 690 m below the islandâs surface; Milrow: 1 million ton, 1969 at 1200 m below surface; and Cannikin: 5 million-ton, 1971 at 1763 m below surface (the worldâs largest underground test). The Department of Energy has conducted monitoring of this site for a number of years and has found little evidence of radionuclide leakage (Sibley and Tornberg, 1982; Burger et al., 2006). We collected a suite of fish samples from areas adjoining Amchitka and tested it for natural and anthropogenic radionuclides. In this report, we report the concentration of gamma-emitting radionuclides (40K, 137Cs, 226Ra, and 226Ra) from a suite of fish samples that we obtained from our collaborators.
This research was completed money allocated during Round 5 of the Citizensâ Monitoring and Technical Assessment Fund (MTA Fund). Clark University was named conservator of these works.
If you have any questions or concerns please contact us at [email protected]://commons.clarku.edu/aleutian/1001/thumbnail.jp
Scavenging, cycling and removal fluxes of 210Po and 210Pb at the Bermuda time-series study site
Author Posting. © The Author(s), 2012. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Deep Sea Research Part II: Topical Studies in Oceanography 93 (2013):108â118, doi:10.1016/j.dsr2.2013.01.005.Quantifying relative affinities of Po and Pb in different populations of marine particulate matter is of great importance in utilizing 210Po as a tracer for carbon cycling. We collected and analyzed water samples for the concentrations of dissolved and total 210Po and 30 210Pb from the upper 600 m of the water column at Bermuda Time-series Study site (September 1999 to September 2000) to investigate their seasonality of concentrations and their activity ratio (210Po/210Pb activity ratio, AR). Sinking particles collected in sediment traps at depths of 500 m, 1500 m, and 3200 m from the Oceanic Flux Program (OFP) time-series sediment traps were analyzed over a period of 12 months (May 1999 to May 2000). The objective was to compare the deficiencies of 210Po with respect to 210Pb in the water column to that measured in the sediment traps and to assess the relative affinities of Po and Pb with different particle pools.
Inventories of 210Po in the upper 500 m water column varied by a factor of 2, indicating seasonal variations of particulate flux dominated the removal of 210Po. The 210Po/210Pb ARs in the dissolved phase were generally less than the secular equilibrium value (1.0) in the upper 600 m, while were generally greater than 1.0 in the particulate phase, indicating higher removal rates of 210Po relative to 210Pb by particulate matter. The measured fluxes of 210Po and 210Pb in the 500 m, 1500 m, and 3200 m traps increased with depth, while the 210Po/210Pb ARs decreased with depth except from May-August 1999. From the measured fluxes of 210Po and 210Pb at these three traps and the concentrations of 210Po and 210Pb in the water column, this region appears to be a sink for 210Pb which is likely brought-in by lateral advection.GHHâs sabbatical leave was supported by Korea Ocean Research and Development Institute (renamed as Korea Institute of Ocean Science and Technology) (PG47900 and PE98742). The Oceanic Flux Program has been supported since inception by the NSF Chemical Oceanography Program, most recently by grants OCE-0325627/0509602, OCE-0623505 and OCE-0927098. Partial support in writing this manuscript was supported by OCE-0961351 (MB)
Report of Sampling and Analytical Activities: Groundwater from the Vicinity of the Industrial Excess Landfill, Uniontown, Ohio
Groundwater samples were collected in two sampling trips, on July 15, 2005 and October 20, 2005. All samples were collected personally by the investigators (Michael E. Ketterer and Mark M. Baskaran), working in the capacity of paid environmental consultants on behalf of the Concerned Citizens of lake Township (CCLT). Water samples were obtained from existing domestic/residential wells, irrigation wells, and one pre-established monitoring well, all of which were located on private property accessed with explicit permission given to CCLT. Samples from irrigation and monitoring wells (DK, GZ, NB, and MW-25s) were collected using a submersible 12V battery powered pump, equipped with fluorinated ethylene- propylene tubing.
This research was completed money allocated during Round 4 of the Citizensâ Monitoring and Technical Assessment Fund (MTA Fund). Clark University was named conservator of these works.
If you have any questions or concerns please contact us at [email protected]://commons.clarku.edu/cclt/1001/thumbnail.jp
Business ecosystem strategy for capital industry: Transcending the classical project management amidst complexity
The capital projects are executed with classical project management; overlooking the inter-organizational system approach of reciprocal relationships. This problem prompts a review of the business ecosystem strategy phenomenon capital projects, more so because it lacks research in this domain. The research questions are relating to classical project management concepts and limitations; business ecosystem and operating strategy actions; and strategy action patterns in capital projects. The paper shows that the ecosystems, in which the capital projects are embedded, are inter-organizational settings; invoking temporal permanence across the series of the projects. The ecosystem strategy concentrates on collaboration, innovation, and competition to create value and to sustain the systemic health and performance in a changing environment; while the project management approach remains around planning, executing, and control. Ecosystem strategy in projects broaches the holism and leverages upon the complexity of interdependence. The paper contributes to theory and practice by extending the macro view of projects and deploying the strength of interdependence. The ecosystem strategy phenomenon provides a paradigm to conduct positivist research; meeting the need for the systemic theorization of the inter-organizational aspects of capital projects, and balancing the need for advances in the development of theory and practical significance
Review of Evidence for Anthropogenic Radioactivity at the Industrial Excess Landfill, Uniontown, Ohio
This report considers the following two questions concerning the Industrial Excess Landfill (IEL): 1) What evidence exists for the presence of âanthropogenic radioactivityâ in the IEL, its surface soils, and the groundwater in the vicinity of the site? and 2) Have the previous environmental sampling and analysis efforts, conducted by USEPA and Ohio EPA, been appropriately designed and conducted so that best available methodology, maximally protective of the environment and human health, has been used to detect any potential anthropogenic radioactivity?
This research was completed money allocated during Round 4 of the Citizensâ Monitoring and Technical Assessment Fund (MTA Fund). Clark University was named conservator of these works.
If you have any questions or concerns please contact us at [email protected]://commons.clarku.edu/cclt/1000/thumbnail.jp
Sedimentary geochemical record of humanâinduced environmental changes in the Lake Brunnsviken watershed, Sweden
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/110094/1/lno20044951560.pd
Remote real-time collaboration through synchronous exchange of digitised human-workpiece interactions
In this highly globalised manufacturing ecosystem, product design and verification activities, production and inspection processes, and technical support services are spread across global supply chains and customer networks. Therefore, collaborative infrastructures that enable global teams to collaborate with each other in real-time in performing complex manufacturing-related tasks is highly desirable. This work demonstrates the design and implementation of a remote real-time collaboration platform by using human motion capture technology powered by infrared light based depth imaging sensors and a synchronous data transfer protocol from computer networks. The unique functionality of the proposed platform is the sharing of physical contexts during a collaboration session by not only exchanging human actions but also the effects of those actions on the workpieces and the task environment. Results show that this platform could enable teams to remotely work on a common engineering problem at the same time and also get immediate feedback from each other making it valuable for collaborative design, inspection and verifications tasks in the factories of the future. An additional benefit of the implemented platform is its use of low cost off the shelf equipment thereby making it accessible to SMEs that are connected to larger organisations via complex supply chains
Particulate 210Po and 210Pb from R/V Knorr KN199-04, KN204-01 in the Subtropical northern Atlantic Ocean from 2010-2011 (U.S. GEOTRACES NAT project)
Dataset: GT10-11 - Particulate Po PbParticulate 210Po and 210Pb from R/V Knorr KN199-04, KN204-01 in the Subtropical northern Atlantic Ocean from 2010-2011.
For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/3917NSF Division of Ocean Sciences (NSF OCE) OCE-096135
Effects of flow rates and composition of the filter, and decay/ingrowth correction factors involved with the determination of in situ particulate \u3csup\u3e210\u3c/sup\u3ePo and \u3csup\u3e210\u3c/sup\u3ePb in seawater
Accurate measurements of particulate 210Po (210Pop) and 210Pb (210Pbp) are required in the investigation of (i) partitioning of Po and Pb between particulate and dissolved phases and (ii) export estimates of carbon and other key trace metals from the euphotic zone via sinking particulate matter. Based on the intercomparison of different composition of the filter material (QMA, Supor, Millipore, and Pall GN6) and flow rates (2 to 8 L min), we show how these factors affect the measured concentrations of 210Pop and 210Pbp and their activity ratios (AR). As such, we recommend using Supor 0.4 ÎŒm filter and a flow rate of up to 8 L/min for the measurements of210Pop and 210Pbp. Furthermore, we inter-compared 210Pop and 210Pbp obtained by small-volume McLane and large-volume MULVFS pumps. The activities of 210Pop in MULVFS filter samples are somewhat higher than that of McLane filter samples, whereas the 210Pop/210Pb AR collected by McLane pump is distinctly lower, suggesting some fractionation in the collection process by the pumping systems. Likewise comparison of vertical profiles of 210Pop and 210Pbp obtained using McLane pumps by two independent research groups at the two intercalibration stations in the Pacific Ocean show quite similar values except in the mesopelagic waters, suggesting possible uneven loading and presence of larger gelatinous plankton in the filter. Finally, we append a detailed analysis of various correction factors for the accurate calculation of in situ 210Po and 210Pb. Presented results are relevant to the worldwide community that uses 210Po-210Pb as tracers in aquatic systems
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