Science.gov

Sample records for air concentration dac

  1. Calculation Package: Derivation of Facility-Specific Derived Air Concentration (DAC) Values in Support of Spallation Neutron Source Operations

    SciTech Connect

    McLaughlin, David A

    2009-12-01

    Derived air concentration (DAC) values for 175 radionuclides* produced at the Oak Ridge National Laboratory (ORNL) Spallation Neutron Source (SNS), but not listed in Appendix A of 10 CFR 835 (01/01/2009 version), are presented. The proposed DAC values, ranging between 1 E-07 {micro}Ci/mL and 2 E-03 {micro}Ci/mL, were calculated in accordance with the recommendations of the International Commission on Radiological Protection (ICRP), and are intended to support an exemption request seeking regulatory relief from the 10 CFR 835, Appendix A, requirement to apply restrictive DACs of 2E-13 {micro}Ci/mL and 4E-11 {micro}Ci/mL and for non-listed alpha and non-alpha-emitting radionuclides, respectively.

  2. Derivation of continuous air monitor equations for DAC and DAC-h.

    PubMed

    Justus, Alan L

    2010-05-01

    Equations are derived that provide the numerical algorithms necessary for the calculations of both concentration (such as #DAC) and exposure (such as #DAC-h) within continuous air monitors (CAMs) employing collection media. Both calculations utilize measured counts over certain CAM counting intervals. The relationship to similar, although oft misinterpreted, equations given in International Organization for Standardization Standard 11929-5:2005 is detailed.

  3. 10 CFR Appendix C to Part 835 - Derived Air Concentration (DAC) for Workers From External Exposure During Immersion in a Cloud of...

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... Exposure During Immersion in a Cloud of Airborne Radioactive Material C Appendix C to Part 835 Energy... Concentration (DAC) for Workers From External Exposure During Immersion in a Cloud of Airborne Radioactive...-infinite cloud of airborne radioactive material. The DACs listed in this appendix may be modified to...

  4. 10 CFR Appendix C to Part 835 - Derived Air Concentration (DAC) for Workers From External Exposure During Immersion in a Cloud of...

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... Exposure During Immersion in a Cloud of Airborne Radioactive Material C Appendix C to Part 835 Energy... Concentration (DAC) for Workers From External Exposure During Immersion in a Cloud of Airborne Radioactive...-infinite cloud of airborne radioactive material. The DACs listed in this appendix may be modified to...

  5. 10 CFR Appendix C to Part 835 - Derived Air Concentration (DAC) for Workers From External Exposure During Immersion in a Cloud of...

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... Exposure During Immersion in a Cloud of Airborne Radioactive Material C Appendix C to Part 835 Energy... Concentration (DAC) for Workers From External Exposure During Immersion in a Cloud of Airborne Radioactive...-infinite cloud of airborne radioactive material. The DACs listed in this appendix may be modified to...

  6. 10 CFR Appendix C to Part 835 - Derived Air Concentration (DAC) for Workers From External Exposure During Immersion in a Cloud of...

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... Exposure During Immersion in a Cloud of Airborne Radioactive Material C Appendix C to Part 835 Energy... Concentration (DAC) for Workers From External Exposure During Immersion in a Cloud of Airborne Radioactive...-infinite cloud of airborne radioactive material. The DACs listed in this appendix may be modified to...

  7. 10 CFR Appendix C to Part 835 - Derived Air Concentration (DAC) for Workers From External Exposure During Immersion in a Cloud of...

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... Exposure During Immersion in a Cloud of Airborne Radioactive Material C Appendix C to Part 835 Energy... Concentration (DAC) for Workers From External Exposure During Immersion in a Cloud of Airborne Radioactive...-infinite cloud of airborne radioactive material. The DACs listed in this appendix may be modified to...

  8. 10 CFR 835.209 - Concentrations of radioactive material in air.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 10 Energy 4 2013-01-01 2013-01-01 false Concentrations of radioactive material in air. 835.209... External Exposure § 835.209 Concentrations of radioactive material in air. (a) The derived air concentration (DAC) values given in appendices A and C of this part shall be used in the control of...

  9. 10 CFR 835.209 - Concentrations of radioactive material in air.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 10 Energy 4 2014-01-01 2014-01-01 false Concentrations of radioactive material in air. 835.209... External Exposure § 835.209 Concentrations of radioactive material in air. (a) The derived air concentration (DAC) values given in appendices A and C of this part shall be used in the control of...

  10. 10 CFR 835.209 - Concentrations of radioactive material in air.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 10 Energy 4 2011-01-01 2011-01-01 false Concentrations of radioactive material in air. 835.209... External Exposure § 835.209 Concentrations of radioactive material in air. (a) The derived air concentration (DAC) values given in appendices A and C of this part shall be used in the control of...

  11. 10 CFR 835.209 - Concentrations of radioactive material in air.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 10 Energy 4 2012-01-01 2012-01-01 false Concentrations of radioactive material in air. 835.209... External Exposure § 835.209 Concentrations of radioactive material in air. (a) The derived air concentration (DAC) values given in appendices A and C of this part shall be used in the control of...

  12. Air Data - Concentration Map

    EPA Pesticide Factsheets

    Make a map of daily concentrations over several days. The daily air quality can be displayed in terms of the Air Quality Index or in concentration ranges for certain PM species like organic carbon, nitrates, and sulfates.

  13. DACS upgrade acceptance test procedure

    SciTech Connect

    Zuehlke, A.C.

    1994-09-28

    The readiness of the Data Acquisition and Control System (DACS) to provide monitoring and control of the mixer pump, directional drive system, and the instrumentation associated with the SY-101 tank and support systems, and the proper functioning of the DACS with new Model 984-785 Programmable Logic Controllers (PLCs), new MODBUS PLUS version 2.01 software for the PLCs, and version 3.72 of the GENESIS software will be systematically evaluated by performance of this procedure. The DACS, which is housed in a trailer located just outside of the north fence at the SY tank farm, receives input signals from a variety of sensors located in and around the SY-101 tanks. These sensors provide information such as: tank vapor space and ventilation system H{sub 2} concentration; tank waste temperature; tank pressure; waste density; operating pump parameters such as speed, flow, rotational position, discharge pressure, and internal temperature; strain (for major equipment); and waste level. The output of these sensors is conditioned and transmitted to the DACS computers where these signals are displayed, recorded, and monitored for out-of-specification conditions. If abnormal conditions are detected, then, in certain situations, the DACS automatically generates alarms and causes the system to abort pump operations.

  14. DACS upgrade acceptance test report

    SciTech Connect

    Zuehlke, A.C.

    1994-12-21

    The DACS, which is housed in a trailer located just outside of the north fence at the SY tank farm, receives input signals from a variety of sensors located in and around the SY-101 tank. These sensors provide information such as: (1) tank vapor space and ventilation system H{sub 2} concentration; (2) tank waste temperature; (3) tank pressure; (4) waste density; (5) operating pump parameters such as speed, flow, rotational position, discharge pressure, and internal temperature; (6) strain (for major equipment); and (7) waste level. The output of these sensors is conditioned and transmitted to the DACS computers where these signals are displayed, recorded, and monitored for out-of-specification conditions. If abnormal conditions are detected, then, in certain situations, the DACS automatically generates alarms and causes the system to abort pump operations. The report documents testing performed per WHC-SD-WM-ATP-082. Rev. 0-13.

  15. INDOOR AIR CONCENTRATION UNIT CONVERSIONS

    EPA Science Inventory

    Migration of volatile chemicals from the subsurface into overlying buildings is called vapor intrusion (VI). Volatile organic chemicals in contaminated soils or groundwater can emit vapors, which can migrate through subsurface soils and may enter the indoor air of overlying buil...

  16. Disciplinary Action Committee (DAC)

    ERIC Educational Resources Information Center

    Notar, Charles; Riley, Gena; Thornburg, Roland; Owens, Lynetta; Harper, Cynthia

    2009-01-01

    The College of Education and Professional Studies (CEPS) provides an environment in which all students can learn. The term "students" encompasses anyone enrolled in a course provided by the College. The DAC was formed to protect the health, safety, and general welfare of students, educators, and those who participate in conjunction with…

  17. Electrets to measure ion concentration in air.

    PubMed

    Kotrappa, P

    2005-08-01

    Positive and negative ions are produced in air, mainly due to radon and terrestrial/cosmic radiation sources. Measuring ion concentration in air indirectly provides a measure of these sources. Electrets (electrically charged pieces of Teflon), when exposed in the environment, collect ions of opposite sign leading to a measurable decrease in charge, depending upon the exposure time and ion concentration. This work describes a method of correlating electret discharge rate to the ion concentration as measured by a calibrated ion density meter. Once calibrated, electrets can then be used to measure ion concentration of either sign. The ion concentration in ambient air was measured to be about 200 ions mL(-1), measured over several hours. Both positive and negative ion concentrations were similar. In a typical room, negative ion concentration was about 3,500 ions mL(-1), and, surprisingly, there were no positive ions at all in that room. Being an integrating passive device, the method provides the unique possibility of measuring low or high concentrations of positive or negative ions over extended periods, which is difficult to do with other ion concentration measuring instruments.

  18. The Air Force concentrating photovoltaic array program

    NASA Technical Reports Server (NTRS)

    Geis, Jack W.

    1987-01-01

    A summary is given of Air Force solar concentrator projects beginning with the Rockwell International study program in 1977. The Satellite Materials Hardening Programs (SMATH) explored and developed techniques for hardening planar solar cell array power systems to the combined nuclear and laser radiation threat environments. A portion of program dollars was devoted to developing a preliminary design for a hardened solar concentrator. The results of the Survivable Concentrating Photovoltaic Array (SCOPA) program, and the design, fabrication and flight qualification of a hardened concentrator panel are discussed.

  19. Observations on using inside air concentrations as a predictor of outside air concentrations

    SciTech Connect

    Hawkley, Gavin; Whicker, Jeffrey; Harris, Jason

    2015-04-01

    Here, excavations of radiological material were performed within confined structures with known operational parameters, such as a filtered exhaust system with known filtration efficiency. Given the known efficiency, the assumption could be made that the air concentrations of radioactivity measured outside the structure would be proportional to the air concentrations measured inside the structure. To investigate this assumption, the inside concentration data was compared with the outside concentration data. The correlation of the data suggested that the inside concentrations were not a good predictor of the outside concentrations. This poor correlation was deemed to be a result of operational unknowns within the structures.

  20. Observations on using inside air concentrations as a predictor of outside air concentrations

    DOE PAGES

    Hawkley, Gavin; Whicker, Jeffrey; Harris, Jason

    2015-04-01

    Here, excavations of radiological material were performed within confined structures with known operational parameters, such as a filtered exhaust system with known filtration efficiency. Given the known efficiency, the assumption could be made that the air concentrations of radioactivity measured outside the structure would be proportional to the air concentrations measured inside the structure. To investigate this assumption, the inside concentration data was compared with the outside concentration data. The correlation of the data suggested that the inside concentrations were not a good predictor of the outside concentrations. This poor correlation was deemed to be a result of operational unknownsmore » within the structures.« less

  1. Scavenging ratios based on inflow air concentrations

    SciTech Connect

    Davis, W.E.; Dana, M.T.; Lee, R.N.; Slinn, W.G.N.; Thorp, J.M.

    1991-07-01

    Scavenging ratios were calculated from field measurements made during April 1985. Event precipitation samples were collected at the surface, but air chemistry measurements in the air mass feeding the precipitation were made from an aircraft. In contrast, ratios calculated in previous studies have used air concentration and precipitation chemistry data from only surface measurements. Average scavenging ratios were calculated for SO{sub 4}{sup 2{minus}}, NO{sub 3}{sup {minus}}, NH{sub 4}{sup +}, total sulfate, total nitrate, and total ammonium for 5 events; the geometric mean of these scavenging ratios were 8.5 {times} 10{sup 5}, 5.6 {times} 10{sup 6}, 4.3 {times} 10{sup 5}, 3.4 {times} 10{sup 5}, 2.4 {times} 10{sup 6}, and 9.7 {times} 10{sup 4}, respectively. These means are similar to but less variable than previous ratios formed using only surface data.

  2. GMS/DACS interface acceptance test report

    SciTech Connect

    Zuehlke, A.C.

    1994-10-10

    The DACS, which is housed in a trailer located just outside of the north fence at the SY tank farm, receives input signals from a variety of sensors located in and around the SY-101 tank. These sensors provide information such as: tank vapor space and ventilation system H{sub 2} concentration; tank waste temperature; tank pressure; waste density; operating pump parameters such as speed, flow, rotational position, discharge pressure, and internal temperature; strain (for major equipment); and waste level. The output of these sensors is conditioned and transmitted to the DACS computers where these signals are displayed, recorded, and monitored for out-of-specification conditions. If abnormal conditions are detected, then, in certain situations, the DACS automatically generates alarms and causes the system to abort pump operations. The portions of the system to be tested include: new RGA5 gas monitor; existing gas chromatographs; FTIR; B and K (Photo) NH{sub 3} equipment; any new or changed Genesis screens; and I/O Drop 13.

  3. 10 CFR Appendix A to Part 835 - Derived Air Concentrations (DAC) for Controlling Radiation Exposure to Workers at DOE Facilities

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... - - St// K-42 2 E−06 - - 1 E+05 - - E// K-43 9 E−07 - - 3 E+04 - - ET// K-44 8 E−06 - - 2 E+05 - - ET// K...−06 - 1 E+05 7 E+04 - ET/St/ Sn-123m 1 E−05 7 E−06 - 4 E+05 2 E+05 - ET/ET/ Sn-123 3 E−07 1 E−07 - 1 E...-121 (Vapor) - 4 E−06 - - 1 E+05 - /T/ I-121 8 E−06 - - 3 E+05 - - T// I-123 (Methyl) 1 E−06 - - 7...

  4. 10 CFR Appendix A to Part 835 - Derived Air Concentrations (DAC) for Controlling Radiation Exposure to Workers at DOE Facilities

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... - - St// K-42 2 E−06 - - 1 E+05 - - E// K-43 9 E−07 - - 3 E+04 - - ET// K-44 8 E−06 - - 2 E+05 - - ET// K...−06 - 1 E+05 7 E+04 - ET/St/ Sn-123m 1 E−05 7 E−06 - 4 E+05 2 E+05 - ET/ET/ Sn-123 3 E−07 1 E−07 - 1 E...-121 (Vapor) - 4 E−06 - - 1 E+05 - /T/ I-121 8 E−06 - - 3 E+05 - - T// I-123 (Methyl) 1 E−06 - - 7...

  5. 10 CFR Appendix A to Part 835 - Derived Air Concentrations (DAC) for Controlling Radiation Exposure to Workers at DOE Facilities

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... - - St// K-42 2 E−06 - - 1 E+05 - - E// K-43 9 E−07 - - 3 E+04 - - ET// K-44 8 E−06 - - 2 E+05 - - ET// K...−06 - 1 E+05 7 E+04 - ET/St/ Sn-123m 1 E−05 7 E−06 - 4 E+05 2 E+05 - ET/ET/ Sn-123 3 E−07 1 E−07 - 1 E...-121 (Vapor) - 4 E−06 - - 1 E+05 - /T/ I-121 8 E−06 - - 3 E+05 - - T// I-123 (Methyl) 1 E−06 - - 7...

  6. 10 CFR Appendix B to Part 20 - Annual Limits on Intake (ALIs) and Derived Air Concentrations (DACs) of Radionuclides for...

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... Californium Cf 98 Carbon C 6 Cerium Ce 58 Cesium Cs 55 Chlorine Cl 17 Chromium Cr 24 Cobalt Co 27 Copper Cu 29... Ru 44 Samarium Sm 62 Scandium Sc 21 Selenium Se 34 Silicon Si 14 Silver Ag 47 Sodium Na 11...

  7. 10 CFR Appendix B to Part 20 - Annual Limits on Intake (ALIs) and Derived Air Concentrations (DACs) of Radionuclides for...

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... Californium Cf 98 Carbon C 6 Cerium Ce 58 Cesium Cs 55 Chlorine Cl 17 Chromium Cr 24 Cobalt Co 27 Copper Cu 29... Ru 44 Samarium Sm 62 Scandium Sc 21 Selenium Se 34 Silicon Si 14 Silver Ag 47 Sodium Na 11...

  8. 10 CFR Appendix B to Part 20 - Annual Limits on Intake (ALIs) and Derived Air Concentrations (DACs) of Radionuclides for...

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... Californium Cf 98 Carbon C 6 Cerium Ce 58 Cesium Cs 55 Chlorine Cl 17 Chromium Cr 24 Cobalt Co 27 Copper Cu 29... Ru 44 Samarium Sm 62 Scandium Sc 21 Selenium Se 34 Silicon Si 14 Silver Ag 47 Sodium Na 11...

  9. 10 CFR Appendix B to Part 20 - Annual Limits on Intake (ALIs) and Derived Air Concentrations (DACs) of Radionuclides for...

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... Californium Cf 98 Carbon C 6 Cerium Ce 58 Cesium Cs 55 Chlorine Cl 17 Chromium Cr 24 Cobalt Co 27 Copper Cu 29... Ru 44 Samarium Sm 62 Scandium Sc 21 Selenium Se 34 Silicon Si 14 Silver Ag 47 Sodium Na 11...

  10. 10 CFR Appendix A to Part 835 - Derived Air Concentrations (DAC) for Controlling Radiation Exposure to Workers at DOE Facilities

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... established to describe the absorption type of the materials from the respiratory tract into the blood. The... that irradiation from gas within the lungs might increase the dose by 20%. 3 A dash indicates no...

  11. 10 CFR Appendix A to Part 835 - Derived Air Concentrations (DAC) for Controlling Radiation Exposure to Workers at DOE Facilities

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... established to describe the absorption type of the materials from the respiratory tract into the blood. The... that irradiation from gas within the lungs might increase the dose by 20%. 3 A dash indicates no...

  12. 10 CFR Appendix B to Part 20 - Annual Limits on Intake (ALIs) and Derived Air Concentrations (DACs) of Radionuclides for...

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... different radionuclides. It should be noted that the classification of a compound as Class D, W, or Y is based on the chemical form of the compound and does not take into account the radiological half-life of different radioisotopes. For this reason, values are given for Class D, W, and Y compounds, even for...

  13. 35. View of data and analysis console (DAC), located in ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    35. View of data and analysis console (DAC), located in MWOC facility in transmitter building no. 102, showing clock and missile impact predictor time. - Clear Air Force Station, Ballistic Missile Early Warning System Site II, One mile west of mile marker 293.5 on Parks Highway, 5 miles southwest of Anderson, Anderson, Denali Borough, AK

  14. Preface: SciDAC 2009

    NASA Astrophysics Data System (ADS)

    Simon, Horst

    2009-07-01

    By almost any measure, the SciDAC community has come a long way since DOE launched the SciDAC program back in 2001. At the time, we were grappling with how to efficiently run applications on terascale systems (the November 2001 TOP500 list was led by DOE's ASCI White IBM system at Lawrence Livermore achieving 7.2 teraflop/s). And the results stemming from the first round of SciDAC projects were summed up in two-page reports. The scientific results were presented at annual meetings, which were by invitation only and typically were attended by about 75 researchers. Fast forward to 2009 and we now have SciDAC Review, a quarterly magazine showcasing the scientific computing contributions of SciDAC projects and related programs, all focused on presenting a comprehensive look at Scientific Discovery through Advanced Computing. That is also the motivation behind the annual SciDAC conference that in 2009 was held from June 14-18 in San Diego. The annual conference, which can also be described as a celebration of all things SciDAC, grew out those meetings organized in the early days of the program. In 2005, the meeting was held in San Francisco and attendance was opened up to all members of the SciDAC community. The schedule was also expanded to include a keynote address, plenary speakers and other features found in a conference format. This year marks the fifth such SciDAC conference, which now comprises four days of computational science presentations, multiple poster sessions and, since last year, an evening event showcasing simulations and modeling runs resulting from SciDAC projects. The fifth annual SciDAC conference was remarkable on several levels. The primary purpose, of course, is to showcase the research accomplishments resulting from SciDAC programs in particular and computational science in general. It is these accomplishments, represented in 38 papers and 52 posters, that comprise this set of conference proceedings. These proceedings can stand alone as

  15. Long-memory property in air pollutant concentrations

    NASA Astrophysics Data System (ADS)

    Chelani, Asha

    2016-05-01

    In the present paper, long-memory in air pollutant concentrations is reviewed and outcome of the past studies is analyzed to provide the possible mechanism behind temporal evolution of air pollutant concentrations. It is observed that almost all the studies show air pollutant concentrations over time possess persistence up to a certain limit. Self-organized criticality of air pollution, multiplicative process of pollutant concentrations, and uniformity in emission sources leading to self-organized criticality are few of the phenomena behind the persistent property of air pollutant concentrations. The self-organized criticality of air pollution is linked to atmosphere's self-cleansing mechanism. This demonstrates that inspite of increasing anthropogenic emissions, self-organized criticality of air pollution is sustained and has low influence of human interventions. In the future, this property may, however, be perturbed due to continuous air pollution emissions, which may influence the accuracy in predictions.

  16. Preface: SciDAC 2007

    NASA Astrophysics Data System (ADS)

    Keyes, David E.

    2007-09-01

    It takes a village to perform a petascale computation—domain scientists, applied mathematicians, computer scientists, computer system vendors, program managers, and support staff—and the village was assembled during 24-28 June 2007 in Boston's Westin Copley Place for the third annual Scientific Discovery through Advanced Computing (SciDAC) 2007 Conference. Over 300 registered participants networked around 76 posters, focused on achievements and challenges in 36 plenary talks, and brainstormed in two panels. In addition, with an eye to spreading the vision for simulation at the petascale and to growing the workforce, 115 participants—mostly doctoral students and post-docs complementary to the conferees—were gathered on 29 June 2007 in classrooms of the Massachusetts Institute of Technology for a full day of tutorials on the use of SciDAC software. Eleven SciDAC-sponsored research groups presented their software at an introductory level, in both lecture and hands-on formats that included live runs on a local BlueGene/L. Computation has always been about garnering insight into the behavior of systems too complex to explore satisfactorily by theoretical means alone. Today, however, computation is about much more: scientists and decision makers expect quantitatively reliable predictions from simulations ranging in scale from that of the Earth's climate, down to quarks, and out to colliding black holes. Predictive simulation lies at the heart of policy choices in energy and environment affecting billions of lives and expenditures of trillions of dollars. It is also at the heart of scientific debates on the nature of matter and the origin of the universe. The petascale is barely adequate for such demands and we are barely established at the levels of resolution and throughput that this new scale of computation affords. However, no scientific agenda worldwide is pushing the petascale frontier on all its fronts as vigorously as SciDAC. The breadth of this conference

  17. Preface: SciDAC 2006

    NASA Astrophysics Data System (ADS)

    Tang, William M., Dr.

    2006-01-01

    The second annual Scientific Discovery through Advanced Computing (SciDAC) Conference was held from June 25-29, 2006 at the new Hyatt Regency Hotel in Denver, Colorado. This conference showcased outstanding SciDAC-sponsored computational science results achieved during the past year across many scientific domains, with an emphasis on science at scale. Exciting computational science that has been accomplished outside of the SciDAC program both nationally and internationally was also featured to help foster communication between SciDAC computational scientists and those funded by other agencies. This was illustrated by many compelling examples of how domain scientists collaborated productively with applied mathematicians and computer scientists to effectively take advantage of terascale computers (capable of performing trillions of calculations per second) not only to accelerate progress in scientific discovery in a variety of fields but also to show great promise for being able to utilize the exciting petascale capabilities in the near future. The SciDAC program was originally conceived as an interdisciplinary computational science program based on the guiding principle that strong collaborative alliances between domain scientists, applied mathematicians, and computer scientists are vital to accelerated progress and associated discovery on the world's most challenging scientific problems. Associated verification and validation are essential in this successful program, which was funded by the US Department of Energy Office of Science (DOE OS) five years ago. As is made clear in many of the papers in these proceedings, SciDAC has fundamentally changed the way that computational science is now carried out in response to the exciting challenge of making the best use of the rapid progress in the emergence of more and more powerful computational platforms. In this regard, Dr. Raymond Orbach, Energy Undersecretary for Science at the DOE and Director of the OS has stated

  18. Concentrated Solar Air Conditioning for Buildings Project

    NASA Technical Reports Server (NTRS)

    McLaughlin, Rusty

    2010-01-01

    This slide presentation reviews project to implement the use of solar power to provide air conditioning for NASA buildings. Included is an overall conceptual schematic, and an diagram of the plumbing and instrumentation for the project. The use of solar power to power air conditioning in buildings, particularly in the Southwest, could save a significant amount of money. DOD studies have concluded that air conditioning accounts for 30-60% of total energy expenditures.

  19. Opening Remarks: SciDAC 2007

    NASA Astrophysics Data System (ADS)

    Strayer, Michael

    2007-09-01

    SciDAC work. I am pleased that the President's FY08 budget restores the funding for SciDAC. Quoting from Advanced Scientific Computing Research description in the House Energy and Water Development Appropriations Bill for FY08, "Perhaps no other area of research at the Department is so critical to sustaining U.S. leadership in science and technology, revolutionizing the way science is done and improving research productivity." As a society we need to revolutionize our approaches to energy, environmental and global security challenges. As we go forward along the road to the X-scale generation, the use of computation will continue to be a critical tool along with theory and experiment in understanding the behavior of the fundamental components of nature as well as for fundamental discovery and exploration of the behavior of complex systems. The foundation to overcome these societal challenges will build from the experiences and knowledge gained as you, members of our SciDAC research teams, work together to attack problems at the tera- and peta- scale. If SciDAC is viewed as an experiment for revolutionizing scientific methodology, then a strategic goal of ASCR program must be to broaden the intellectual base prepared to address the challenges of the new X-scale generation of computing. We must focus our computational science experiences gained over the past five years on the opportunities introduced with extreme scale computing. Our facilities are on a path to provide the resources needed to undertake the first part of our journey. Using the newly upgraded 119 teraflop Cray XT system at the Leadership Computing Facility, SciDAC research teams have in three days performed a 100-year study of the time evolution of the atmospheric CO2 concentration originating from the land surface. The simulation of the El Nino/Southern Oscillation which was part of this study has been characterized as `the most impressive new result in ten years' gained new insight into the behavior of

  20. A Life Cycle Assessment Case Study of Coal-Fired Electricity Generation with Humidity Swing Direct Air Capture of CO2 versus MEA-Based Postcombustion Capture.

    PubMed

    van der Giesen, Coen; Meinrenken, Christoph J; Kleijn, René; Sprecher, Benjamin; Lackner, Klaus S; Kramer, Gert Jan

    2017-01-17

    Most carbon capture and storage (CCS) envisions capturing CO2 from flue gas. Direct air capture (DAC) of CO2 has hitherto been deemed unviable because of the higher energy associated with capture at low atmospheric concentrations. We present a Life Cycle Assessment of coal-fired electricity generation that compares monoethanolamine (MEA)-based postcombustion capture (PCC) of CO2 with distributed, humidity-swing-based direct air capture (HS-DAC). Given suitable temperature, humidity, wind, and water availability, HS-DAC can be largely passive. Comparing energy requirements of HS-DAC and MEA-PCC, we find that the parasitic load of HS-DAC is less than twice that of MEA-PCC (60-72 kJ/mol versus 33-46 kJ/mol, respectively). We also compare other environmental impacts as a function of net greenhouse gas (GHG) mitigation: To achieve the same 73% mitigation as MEA-PCC, HS-DAC would increase nine other environmental impacts by on average 38%, whereas MEA-PCC would increase them by 31%. Powering distributed HS-DAC with photovoltaics (instead of coal) while including recapture of all background GHG, reduces this increase to 18%, hypothetically enabling coal-based electricity with net-zero life-cycle GHG. We conclude that, in suitable geographies, HS-DAC can complement MEA-PCC to enable CO2 capture independent of time and location of emissions and recapture background GHG from fossil-based electricity beyond flue stack emissions.

  1. Preface: SciDAC 2005

    NASA Astrophysics Data System (ADS)

    Mezzacappa, Anthony

    2005-01-01

    On 26-30 June 2005 at the Grand Hyatt on Union Square in San Francisco several hundred computational scientists from around the world came together for what can certainly be described as a celebration of computational science. Scientists from the SciDAC Program and scientists from other agencies and nations were joined by applied mathematicians and computer scientists to highlight the many successes in the past year where computation has led to scientific discovery in a variety of fields: lattice quantum chromodynamics, accelerator modeling, chemistry, biology, materials science, Earth and climate science, astrophysics, and combustion and fusion energy science. Also highlighted were the advances in numerical methods and computer science, and the multidisciplinary collaboration cutting across science, mathematics, and computer science that enabled these discoveries. The SciDAC Program was conceived and funded by the US Department of Energy Office of Science. It is the Office of Science's premier computational science program founded on what is arguably the perfect formula: the priority and focus is science and scientific discovery, with the understanding that the full arsenal of `enabling technologies' in applied mathematics and computer science must be brought to bear if we are to have any hope of attacking and ultimately solving today's computational Grand Challenge problems. The SciDAC Program has been in existence for four years, and many of the computational scientists funded by this program will tell you that the program has given them the hope of addressing their scientific problems in full realism for the very first time. Many of these scientists will also tell you that SciDAC has also fundamentally changed the way they do computational science. We begin this volume with one of DOE's great traditions, and core missions: energy research. As we will see, computation has been seminal to the critical advances that have been made in this arena. Of course, to

  2. Measuring Concentrations of Particulate 140La in the Air

    DOE PAGES

    Okada, Colin E.; Kernan, Warnick; Keillor, Martin; ...

    2016-01-01

    This article discusses deployment of air-samplers to measure the concentration of radioactive material in the air during the Full-Scale Radiological Dispersal Device experiments. Positioned 100-600 meters downwind of the release point, the filters were collected immediately and analyzed in a field laboratory. The article discusses quantities for total activity collected on the air filters as well as additional information to compute the average or integrated air concentrations. In the case of a public emergency, this type of information would be important for decision makers and responders.

  3. Concentrations of selected contaminants in cabin air of airbus aircrafts.

    PubMed

    Dechow, M; Sohn, H; Steinhanses, J

    1997-07-01

    The concentrations of selected air quality parameters in aircraft cabins were investigated including particle numbers in cabin air compared to fresh air and recirculation air, the microbiological contamination and the concentration of volatile organic compounds (VOC). The Airbus types A310 of Swissair and A340 of Lufthansa were used for measurements. The particles were found to be mainly emitted by the passengers, especially by smokers. Depending on recirculation filter efficiency the recirculation air contained a lower or equal amount of particles compared to the fresh air, whereas the amount of bacteria exceeded reported concentrations within other indoor spaces. The detected species were mainly non-pathogenic, with droplet infection over short distances identified as the only health risk. The concentration of volatile organic compounds (VOC) were well below threshold values. Ethanol was identified as the compound with the highest amount in cabin air. Further organics were emitted by the passengers--as metabolic products or by smoking--and on ground as engine exhaust (bad airport air quality). Cleaning agents may be the source of further compounds.

  4. Minanre Gas Concentrators For Air Sampling

    SciTech Connect

    Dr. Seung Ho Hong

    2001-03-01

    The goal of this project was to demonstrate the feasibility of a compact, lightweight, gas-sampling device with rapid-cycle-time characteristics. The highlights of our Phase I work include: (1) Demonstration of a compact gas sampler with integrated heater. This device has an order of magnitude greater adsorption capacity and much faster heating/cooling times than commercial sorbent tubes. (2) Completion of computational fluid dynamics modeling of the gas sampler to determine airflow characteristics for various design options. These modeling efforts guided the development and testing of the Mesochannel Gas Sampler prototype. (3) Testing of the Mesochannel Gas Sampler in parallel with tests of two packed-bed samplers. These tests showed the Mesochannel Gas Sampler represents a substantial improvement compared with the packed-bed approach. Our mesochannel heat-exchanger/adsorber architecture allows very efficient use of adsorbent mass, high adsorbent loadings, and very low pressure drop, which makes possible very high air-sampling rates using a simple, low-power fan. This device is well-suited for collecting samples of trace-level contaminants. The integrated heater, which forms the adsorbent-coated mesochannel walls, allows direct heating of the adsorbent and results in very rapid desorption of the adsorbed species. We believe the Mesochannel Gas Sampler represents a promising technology for the improvement of trace-contaminant detection limits. In our Phase II proposal, we outline several improvements to the gas sampler that will further improve its performance.

  5. [Pharmacological properties of chitosan-coated dialdehyde cellulose (chitosan DAC), a newly developed oral adsorbent (I). Effect of chitosan DAC in normal rats].

    PubMed

    Yoshimoto, H; Nagano, N; Nishitoba, T; Sato, H; Miyata, S; Kusaka, M; Jing, S B; Yamaguchi, T

    1995-08-01

    The effects of chitosan-coated dialdehyde cellulose (chitosan DAC), a newly developed oral adsorbent of urea and ammonia, were examined in an in vitro adsorption study and in normal rats. Chitosan DAC showed high adsorption capacity for urea and ammonia in an in vitro study using the diluted supernatant of rat gastrointestinal fluid. In contrast, Kremezin, an oral charcoal adsorbent (AST-120), had little influence on these substances. In normal rats fed diets containing chitosan DAC (1, 2, 3, 4, 5, 7, and 10% content) for three weeks, increases in fecal wet weight, fecal dry weight and fecal water content were observed in a dose-dependent manner. In addition, chitosan DAC feeding increased fecal excretion of nitrogen and electrolytes (sodium, potassium and chloride ions) and decreased the apparent protein ratio in a dose-dependent manner. There were no obvious effects in serum parameters except that increased levels of protein and albumin and decreased levels of blood urea nitrogen, cholesterol and glucose were observed in rats fed a high concentration of chitosan DAC. In conclusion, these findings suggest the possibility that chitosan DAC treatment might be effective for improving chronic renal failure.

  6. CONCENTRATIONS OF TOXIC AIR POLLUTANTS IN THE U.S. SIMULATED BY AN AIR QUALITY MODEL

    EPA Science Inventory

    As part of the US National Air Toxics Assessment, we have applied the Community Multiscale Air Quality Model, CMAQ, to study the concentrations of twenty gas-phase, toxic, hazardous air pollutants (HAPs) in the atmosphere over the continental United States. We modified the Carbo...

  7. Preface: SciDAC 2008

    NASA Astrophysics Data System (ADS)

    Stevens, Rick

    2008-07-01

    The fourth annual Scientific Discovery through Advanced Computing (SciDAC) Conference was held June 13-18, 2008, in Seattle, Washington. The SciDAC conference series is the premier communitywide venue for presentation of results from the DOE Office of Science's interdisciplinary computational science program. Started in 2001 and renewed in 2006, the DOE SciDAC program is the country's - and arguably the world's - most significant interdisciplinary research program supporting the development of advanced scientific computing methods and their application to fundamental and applied areas of science. SciDAC supports computational science across many disciplines, including astrophysics, biology, chemistry, fusion sciences, and nuclear physics. Moreover, the program actively encourages the creation of long-term partnerships among scientists focused on challenging problems and computer scientists and applied mathematicians developing the technology and tools needed to address those problems. The SciDAC program has played an increasingly important role in scientific research by allowing scientists to create more accurate models of complex processes, simulate problems once thought to be impossible, and analyze the growing amount of data generated by experiments. To help further the research community's ability to tap into the capabilities of current and future supercomputers, Under Secretary for Science, Raymond Orbach, launched the Innovative and Novel Computational Impact on Theory and Experiment (INCITE) program in 2003. The INCITE program was conceived specifically to seek out computationally intensive, large-scale research projects with the potential to significantly advance key areas in science and engineering. The program encourages proposals from universities, other research institutions, and industry. During the first two years of the INCITE program, 10 percent of the resources at NERSC were allocated to INCITE awardees. However, demand for supercomputing resources

  8. Background concentrations of 18 air toxics for North America.

    PubMed

    McCarthy, Michael C; Hafner, Hilary R; Montzka, Stephen A

    2006-01-01

    The U.S. Clean Air Act identifies 188 hazardous air pollutants (HAPs), or "air toxics," associated with adverse human health effects. Of these air toxics, 18 were targeted as the most important in a 10-City Pilot Study conducted in 2001 and 2002 as part of the National Air Toxics Trend Sites Program. In the present analysis, measurements available from monitoring networks in North America were used to estimate boundary layer background concentrations and trends of these 18 HAPs. The background concentrations reported in this study are as much as 85% lower than those reported in recent studies of HAP concentrations. Background concentrations of some volatile organic compounds were analyzed for trends at the 95% confidence level; only carbon tetrachloride (CCI4) and tetrachloroethylene decreased significantly in recent years. Remote background concentrations were compared with the one-in-a-million (i.e., 10(6)) cancer benchmarks to determine the possible causes of health risk in rural and remote areas; benzene, chloroform, formaldehyde, and chromium (Cr) fine particulate were higher than cancer benchmark values. In addition, remote background concentrations were found to contribute between 5% and 99% of median urban concentrations.

  9. Comparison of observed and predicted Kr-85 air concentrations

    SciTech Connect

    Yildiran, M.; Miller, C.W.

    1984-04-25

    A computer code, ANEMOS has been written to estimate concentrations in air and ground deposition rates for Atmospheric Nuclides Emitted from Multiple Operation Sources. This code uses a modified Gaussian plum equation. Output from ANEMOS includes annual-average air concentrations and ground deposition rates of dispersed radionuclides and daughters. To use the environmental transport model properly, some estimate of the models predictive accuracy must be obtained. To validate the ANEMOS model, one year of weekly average Kr-85 concentrations observed at 13 stations located 28 to 144 km distant from continuous point source at the Savannah River Plant (SRP), Aiken, South Carolina, have been used. There was a general tendency for the model to underpredict the observed air concentrations slightly. Pearsons's correlation between pairs of logarithms of observed and predicted annual-average values was r = 0.84. The monthly results tend to show more scatter than do either the seasonal or the annual comparisons. 18 references, 3 figures, 3 tables.

  10. Air concentrations of organochlorine compounds related to wind direction and compared with biota concentration

    SciTech Connect

    Egebaeck, A.L.; Wideqvist, U.; Asplund, L.; Strandell, M.; Alsberg, T.; Litzen, K.; Eriksson, U.; Haeggberg, L.; Zakrisson, S.; Oisson, M.; Bignert, A.

    1995-12-31

    Persistent organic compounds are long-range transported by air. Air samples were collected at two background meteorological stations, one southern at Gotland in the central Baltic and one northern, close to the polar circle. The collection was a part of the Swedish Dioxin Survey Project. Air sampling was carried out from fall 1990 to spring 1991 using a high-volume sampler. Air trajectories suggesting stable weather conditions decided which samples to be analyzed for e.g. PCBs, polychlorinated naphthalenes (PCN), chloroparaffines, HCHs and Toxaphene. The gas-phase concentrations of the seven PCB congeners 28, 52, 101, 118, 138, 153, 180 were in the low pg/m{sup 3} range, while the concentration of the nonortho PCB 77 was about two orders of magnitude lower. High concentrations were usually correlated with SW winds and low concentrations with N to NW winds. Air masses coming from N to both sampling sites, resulted in nearly equal concentrations of the seven PCB congeners. PCNs were found in the gas phase of all samples at the pg/m{sup 3} level (total PCNs). The relative concentrations of the various contaminants were compared between air and four biological matrices collected in the vicinity of the air sampling locations. Cod, Herring and Herring feeding Guillemot from the Baltic and Pike from the northern sampling site were all collected within the Swedish National Monitoring Program.

  11. Sigma Delta Dac Using Vhdl-Ams

    NASA Astrophysics Data System (ADS)

    Utage, S. A.; Dube, R. R.

    2010-11-01

    Sigma Delta Digital to analog converters (DACs) convert a binary number into a voltage directly proportional to the value of the binary number. A variety of applications use DACs including waveform generators and programmable voltage sources. This paper describes a Delta-Sigma DAC implemented in a FPGA. The only external circuitry required is a low pass filter comprised of just one resistor and one capacitor. Internal resource requirements are also minimal. The speed and flexible output structure of the FPGAs make them ideal for this application.

  12. Indoor air VOC concentrations in suburban and rural New Jersey.

    PubMed

    Weisel, Clifford P; Alimokhtari, Shahnaz; Sanders, Paul F

    2008-11-15

    Indoor VOC air concentrations of many compounds are higher than outdoor concentrations due to indoor sources. However, most studies have measured residential indoor air in urban centers so the typical indoor air levels in suburban and rural regions have not been well characterized. Indoor VOC air concentrations were measured in 100 homes in suburban and rural areas in NJ to provide background levels for investigations of the impact from subsurface contamination sources. Of the 57 target compounds, 23 were not detected in any of the homes, and 14 compounds were detected in at least 50% of the homes with detection limits of approximately 1 microg/m3. The common compounds identified included aromatic and aliphatic hydrocarbons from mobile sources, halogenated hydrocarbons commonly used in consumer products or from chlorinated drinking water, acetone and 2-butanone emitted from cosmetic products, and Freons. Typical concentrations were in the low microg/m3 range, though values of tens, hundreds or even thousands of microg/m3 were measured in individual homes in which activities related to specific sources of VOCs were reported. Compounds with known similar sources were highly correlated. The levels observed are consistent with concentrations found in the air of urban homes.

  13. Seasonal variations of air pollutant concentrations within Krasnoyarsk City.

    PubMed

    Mikhailuta, Sergey V; Taseiko, Olga V; Pitt, Anne; Lezhenin, Anatoly A; Zakharov, Yuri V

    2009-02-01

    This paper examines the significant differences in seasonal variations of criteria pollutant concentrations in various parts of a large urban area. These differences are caused by the microclimatic heterogeneity of the city and show the influence of breeze and orographic-type circulations on urban air pollution. The temperature heterogeneity of Krasnoyarsk territory during the winter leads to an increase of 150% in CO air pollution levels in the central part of city. During the summer the orographical heterogeneity of Krasnoyarsk City leads to increases of up to 400% in air pollution for different areas.

  14. Ozone concentrations in air flowing into New York State

    NASA Astrophysics Data System (ADS)

    Aleksic, Nenad; Kent, John; Walcek, Chris

    2016-09-01

    Ozone (O3) concentrations measured at Pinnacle State Park (PSPNY), very close to the southern border of New York State, are used to estimate concentrations in air flowing into New York. On 20% of the ozone season (April-September) afternoons from 2004 to 2015, mid-afternoon 500-m back trajectories calculated from PSPNY cross New York border from the south and spend less than three hours in New York State, in this area of negligible local pollution emissions. One-hour (2p.m.-3p.m.) O3 concentrations during these inflowing conditions were 46 ± 13 ppb, and ranged from a minimum of 15 ppb to a maximum of 84 ppb. On average during 2004-2015, each year experienced 11.8 days with inflowing 1-hr O3 concentrations exceeding 50 ppb, 4.3 days with O3 > 60 ppb, and 1.5 days had O3 > 70 ppb. During the same period, 8-hr average concentrations (10a.m. to 6p.m.) exceeded 50 ppb on 10.0 days per season, while 3.9 days exceeded 60 ppb, and 70 ppb was exceeded 1.2 days per season. Two afternoons of minimal in-state emission influences with high ozone concentrations were analyzed in more detail. Synoptic and back trajectory analysis, including comparison with upwind ozone concentrations, indicated that the two periods were characterized as photo-chemically aged air containing high inflowing O3 concentrations most likely heavily influenced by pollution emissions from states upwind of New York including Pennsylvania, Tennessee, West Virginia, and Ohio. These results suggest that New York state-level attempts to comply with National Ambient Air Quality Standards by regulating in-state O3 precursor NOx and organic emissions would be very difficult, since air frequently enters New York State very close to or in excess of Federal Air Quality Standards.

  15. Spectra of concentration of air pollution for turbulent convection

    SciTech Connect

    Patel, S.R.

    1996-12-31

    Very recently the study of formation and destruction of photochemical smog is increasing at both small and large scale. Also the transport of chemical species through the Planetary Boundary Layer (PBL) of the atmosphere is a key of the global change problem and will have to be parameterized more reliably than in the past. Further, in the air pollution modeling, the usual practice of neglecting the concentration correlation in the atmospheric photochemical reaction has recently been recognized as a source of serious error. So, it is important to study the various aspects of the concentration fluctuations (of air pollution) with chemical reaction. A model of the spectrum of concentration of air pollution with chemical reaction has been developed using the models of Hill and Hill and Clifford. The results obtained are applicable for arbitrary Schmidt number. Further, for the case of pure mixing (without chemical reaction) and the concentration replaced by temperature, the form of the spectra obtained here reduces to the form obtained by Hill and Clifford. This study also shows that, in the case of pure mixing, the concentration decays in a natural manner, but if the concentration selected is that of the chemical reactant, then the effect is that the dispersion of the concentration is much more rapid.

  16. Development of a model for radon concentration in indoor air.

    PubMed

    Jelle, Bjørn Petter

    2012-02-01

    A model is developed for calculation of the radon concentration in indoor air. The model takes into account various important parameters, e.g. radon concentration in ground, radon diffusion resistance of radon barrier, air permeance of ground, air pressure difference between outdoor ground and indoor at ground level, ventilation of the building ground and number of air changes per hour due to ventilation. Characteristic case studies are depicted in selected 2D and 3D graphical plots for easy visualization and interpretation. The radon transport into buildings might be dominated by diffusion, pressure driven flow or a mixture of both depending on the actual values of the various parameters. The results of our work indicate that with realistic or typical values of the parameters, most of the transport of radon from the building ground to the indoor air is due to air leakage driven by pressure differences through the construction. By incorporation of various and realistic values in the radon model, valuable information about the miscellaneous parameters influencing the indoor radon level is gained. Hence, the presented radon model may be utilized as a simple yet versatile and powerful tool for examining which preventive or remedial measures should be carried out to achieve an indoor radon level below the reference level as set by the authorities.

  17. Influence of relative humidity on VOC concentrations in indoor air.

    PubMed

    Markowicz, Pawel; Larsson, Lennart

    2015-04-01

    Volatile organic compounds (VOCs) may be emitted from surfaces indoors leading to compromised air quality. This study scrutinized the influence of relative humidity (RH) on VOC concentrations in a building that had been subjected to water damage. While air samplings in a damp room at low RH (21-22%) only revealed minor amounts of 2-ethylhexanol (3 μg/m(3)) and 2,2,4-trimethyl-1,3-pentanediol diisobutyrate (TXIB, 8 μg/m(3)), measurements performed after a rapid increase of RH (to 58-75%) revealed an increase in VOC concentrations which was 3-fold for 2-ethylhexanol and 2-fold for TXIB. Similar VOC emission patterns were found in laboratory analyses of moisture-affected and laboratory-contaminated building materials. This study demonstrates the importance of monitoring RH when sampling indoor air for VOCs in order to avoid misleading conclusions from the analytical results.

  18. Auditing and assessing air quality in concentrated feeding operations

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The potential adverse effects of concentrated animal feeding operations (CAFO) on the environment are a growing concern. The air quality issues of most concerns to CAFO vary, but generally include ammonia, hydrogen sulfide, particulate matter (PM), volatile organic compounds (VOC), green house gase...

  19. Determination of beryllium concentrations in UK ambient air

    NASA Astrophysics Data System (ADS)

    Goddard, Sharon L.; Brown, Richard J. C.; Ghatora, Baljit K.

    2016-12-01

    Air quality monitoring of ambient air is essential to minimise the exposure of the general population to toxic substances such as heavy metals, and thus the health risks associated with them. In the UK, ambient air is already monitored under the UK Heavy Metals Monitoring Network for a number of heavy metals, including nickel (Ni), arsenic (As), cadmium (Cd) and lead (Pb) to ensure compliance with legislative limits. However, the UK Expert Panel on Air Quality Standards (EPAQS) has highlighted a need to limit concentrations of beryllium (Be) in air, which is not currently monitored, because of its toxicity. The aim of this work was to analyse airborne particulate matter (PM) sampled onto filter papers from the UK Heavy Metals Monitoring Network for quantitative, trace level beryllium determination and compare the results to the guideline concentration specified by EPAQS. Samples were prepared by microwave acid digestion in a matrix of 2% sulphuric acid and 14% nitric acid, verified by the use of Certified Reference Materials (CRMs). The digested samples were then analysed by Inductively Coupled Plasma Mass Spectrometry (ICP-MS). The filters from the UK Heavy Metals Monitoring Network were tested using this procedure and the average beryllium concentration across the network for the duration of the study period was 7.87 pg m-3. The highest site average concentration was 32.0 pg m-3 at Scunthorpe Low Santon, which is significantly lower than levels that are thought to cause harm. However the highest levels were observed at sites monitoring industrial point sources, indicating that beryllium is being used and emitted, albeit at very low levels, from these point sources. Comparison with other metals concentrations and data from the UK National Atmospheric Emissions Inventory suggests that current emissions of beryllium may be significantly overestimated.

  20. Predicting indoor pollutant concentrations, and applications to air quality management

    SciTech Connect

    Lorenzetti, David M.

    2002-10-01

    Because most people spend more than 90% of their time indoors, predicting exposure to airborne pollutants requires models that incorporate the effect of buildings. Buildings affect the exposure of their occupants in a number of ways, both by design (for example, filters in ventilation systems remove particles) and incidentally (for example, sorption on walls can reduce peak concentrations, but prolong exposure to semivolatile organic compounds). Furthermore, building materials and occupant activities can generate pollutants. Indoor air quality depends not only on outdoor air quality, but also on the design, maintenance, and use of the building. For example, ''sick building'' symptoms such as respiratory problems and headaches have been related to the presence of air-conditioning systems, to carpeting, to low ventilation rates, and to high occupant density (1). The physical processes of interest apply even in simple structures such as homes. Indoor air quality models simulate the processes, such as ventilation and filtration, that control pollutant concentrations in a building. Section 2 describes the modeling approach, and the important transport processes in buildings. Because advection usually dominates among the transport processes, Sections 3 and 4 describe methods for predicting airflows. The concluding section summarizes the application of these models.

  1. Estimating the radon concentration in water and indoor air.

    PubMed

    Maged, A F

    2009-05-01

    The paper presents the results of radon concentration measurements in the vicinity of water, indoor air and in contact to building walls. The investigations were carried out using CR-39 track detectors. Samples of ground water flowing out of many springs mostly in Arabian Gulf area except one from Germany have been studied. The results are compared with international recommendations and the values are found to be lower than the recommended value. Measuring the mean indoor radon concentrations in air and in contact to building walls in the dwellings of Kuwait University Campus were found 24.2 +/- 7.7, and 462 +/- 422 Bq m(-3) respectively. These values lead to average effective dose equivalent rates of 1.3 +/- 0.4 and 23 +/- 21 mSv year(-1), respectively.

  2. Variability of air ion concentrations in urban Paris

    NASA Astrophysics Data System (ADS)

    Dos Santos, V. N.; Herrmann, E.; Manninen, H. E.; Hussein, T.; Hakala, J.; Nieminen, T.; Aalto, P. P.; Merkel, M.; Wiedensohler, A.; Kulmala, M.; Petäjä, T.; Hämeri, K.

    2015-12-01

    Air ion concentrations influence new particle formation and consequently the global aerosol as potential cloud condensation nuclei. We aimed to evaluate air ion concentrations and characteristics of new particle formation events (NPF) in the megacity of Paris, France, within the MEGAPOLI (Megacities: Emissions, urban, regional and Global Atmospheric Pollution and climate effects, and Integrated tools for assessment and mitigation) project. We measured air ion number size distributions (0.8-42 nm) with an air ion spectrometer and fine particle number concentrations (> 6 nm) with a twin differential mobility particle sizer in an urban site of Paris between 26 June 2009 and 4 October 2010. Air ions were size classified as small (0.8-2 nm), intermediate (2-7 nm), and large (7-20 nm). The median concentrations of small and large ions were 670 and 680 cm-3, respectively, (sum of positive and negative polarities), whereas the median concentration of intermediate ions was only 20 cm-3, as these ions were mostly present during new particle formation bursts, i.e. when gas-to-particle conversion produced fresh aerosol particles from gas phase precursors. During peaks in traffic-related particle number, the concentrations of small and intermediate ions decreased, whereas the concentrations of large ions increased. Seasonal variations affected the ion population differently, with respect to their size and polarity. NPF was observed in 13 % of the days, being most frequent in spring and late summer (April, May, July, and August). The results also suggest that NPF was favoured on the weekends in comparison to workdays, likely due to the lower levels of condensation sinks in the mornings of weekends (CS weekdays 09:00: 18 × 10-3 s-1; CS weekend 09:00: 8 × 10-3 s-1). The median growth rates (GR) of ions during the NPF events varied between 3 and 7 nm h-1, increasing with the ion size and being higher on workdays than on weekends for intermediate and large ions. The median GR of

  3. Air radon concentration decrease in a waste water treatment plant.

    PubMed

    Juste, B; Ortiz, J; Verdú, G; Martorell, S

    2015-06-01

    (222)Rn is a naturally occurring gas created from the decay of (226)Ra. The long-term health risk of breathing radon is lung cancer. One particular place where indoor radon concentrations can exceed national guidelines is in wastewater treatment plants (WWTPs) where treatment processes may contribute to ambient airborne concentrations. The aim of this paper was to study the radon concentration decrease after the application of corrective measures in a Spanish WWTP. According to first measures, air radon concentration exceeded International Commission Radiologica1 Protection (ICRP) normative (recommends intervention between 400 and 1000 Bq m(-3)). Therefore, the WWTP improved mechanical forced ventilation to lower occupational exposure. This measure allowed to increase the administrative controls, since the limitation of workers access to the plant changed from 2 h d(-1) (considering a maximum permissible dose of 20 mSv y(-1) averaged over 5 y) to 7 h d(-1).

  4. Dual asymmetric centrifugation (DAC)--a new technique for liposome preparation.

    PubMed

    Massing, Ulrich; Cicko, Sanja; Ziroli, Vittorio

    2008-01-04

    This is the first report on the use of a "dual asymmetric centrifuge (DAC)" for preparing liposomes. DAC differs from conventional centrifugation by an additional rotation of the sample around its own vertical axis: While the conventional centrifugation constantly pushes the sample material outwards, this additional rotation constantly forces the sample material towards the center of the centrifuge. This unique combination of two contra rotating movements results in shear forces and thus, in efficient homogenization. We demonstrated that it is possible to prepare liposomes by DAC, by homogenizing a rather concentrated blend of hydrogenated phosphatidylcholine and cholesterol (55:45 mol%) and 0.9% NaCl-solution, which results in a viscous vesicular phospholipid gel (VPG). The resulting VPG can subsequently be diluted to a conventional liposome dispersion. Since DAC is intended to make sterile preparations of liposomes, or to entrap toxic/radioactive compounds, the process was performed within a sealed vial. It could be shown that the DAC speed, the lipid concentration, the homogenization time and the addition of a mixing aid (glass beads) are all critical for the size of the liposomes. Optimized conditions resulted in liposomes of 60+/-5 nm and a trapping efficacy of 56+/-3.3% for the model compound calcein.

  5. BOREAS TGB-7 Ambient Air Herbicide and Organochlorine Concentration Data

    NASA Technical Reports Server (NTRS)

    Waite, Don; Hall, Forrest G. (Editor); Conrad, Sara K. (Editor)

    2000-01-01

    The BOReal Ecosystem-Atmosphere Study Trace Gas Biogeochemistry (BOREAS TGB)-7 team measured the concentration and flux of several agricultural pesticides in air, rainwater, and dry deposition samples in order to determine the associated yearly deposition rates. This data set contains information on the ambient air concentration of seven herbicides [2,4- dichlorophenoxyacidic_acid (2,4-D), bromoxynil, dicamb, 2-methyl-4-chlorophenoxyacetic acid (MCPA), triallate, trifluralin, and diclop-methyl] known to appear in the atmosphere of the Canadian prairies. Also, the concentration of three herbicides (atrazine, alachlor, and metolachlor), two groups of insecticides (lindane and breakdown products and dichloro-diphenyl-trichloroethane (DDT) and breakdown products), and several polychlorinated biphenyls commonly used in the central United States was measured. All of these chemicals are reported, in the literature, to be transported in the atmosphere. Many have been reported to occur in boreal and arctic food chains. The sampling was carried out from 16-Jun to 13-Aug-1993 and 04-May to 20-Jul-1994 at the BOREAS site in the Prince Albert National Park (Waskesiu). The data are stored in tabular ASCII files. The data files are available on a CD-ROM (see document number 20010000884).

  6. A PRINCIPAL COMPONENT ANALYSIS OF THE CLEAN AIR STATUS AND TRENDS NETWORK (CASTNET) AIR CONCENTRATION DATA

    EPA Science Inventory

    The spatial and temporal variability of ambient air concentrations of SO2, SO42-, NO3, HNO3, and NH4+ obtained from EPA's CASTNet was examined using an objective, statistically based technique...

  7. Pathways to Provenance: "DACS" and Creator Descriptions

    ERIC Educational Resources Information Center

    Weimer, Larry

    2007-01-01

    "Describing Archives: A Content Standard" breaks important ground for American archivists in its distinction between creator descriptions and archival material descriptions. Implementations of creator descriptions, many using Encoded Archival Context (EAC), are found internationally. "DACS"'s optional approach of describing…

  8. Evaluation of air quality zone classification methods based on ambient air concentration exposure.

    PubMed

    Freeman, Brian; McBean, Ed; Gharabaghi, Bahram; Thé, Jesse

    2017-05-01

    Air quality zones are used by regulatory authorities to implement ambient air standards in order to protect human health. Air quality measurements at discrete air monitoring stations are critical tools to determine whether an air quality zone complies with local air quality standards or is noncompliant. This study presents a novel approach for evaluation of air quality zone classification methods by breaking the concentration distribution of a pollutant measured at an air monitoring station into compliance and exceedance probability density functions (PDFs) and then using Monte Carlo analysis with the Central Limit Theorem to estimate long-term exposure. The purpose of this paper is to compare the risk associated with selecting one ambient air classification approach over another by testing the possible exposure an individual living within a zone may face. The chronic daily intake (CDI) is utilized to compare different pollutant exposures over the classification duration of 3 years between two classification methods. Historical data collected from air monitoring stations in Kuwait are used to build representative models of 1-hr NO2 and 8-hr O3 within a zone that meets the compliance requirements of each method. The first method, the "3 Strike" method, is a conservative approach based on a winner-take-all approach common with most compliance classification methods, while the second, the 99% Rule method, allows for more robust analyses and incorporates long-term trends. A Monte Carlo analysis is used to model the CDI for each pollutant and each method with the zone at a single station and with multiple stations. The model assumes that the zone is already in compliance with air quality standards over the 3 years under the different classification methodologies. The model shows that while the CDI of the two methods differs by 2.7% over the exposure period for the single station case, the large number of samples taken over the duration period impacts the sensitivity of

  9. Concentrations of mobile source air pollutants in urban microenvironments.

    PubMed

    Fujita, Eric M; Campbell, David E; Arnott, W Patrick; Johnson, Ted; Ollison, Will

    2014-07-01

    Human exposures to criteria and hazardous air pollutants (HAPs) in urban areas vary greatly due to temporal-spatial variations in emissions, changing meteorology, varying proximity to sources, as well as due to building, vehicle, and other environmental characteristics that influence the amounts of ambient pollutants that penetrate or infiltrate into these microenvironments. Consequently, the exposure estimates derived from central-site ambient measurements are uncertain and tend to underestimate actual exposures. The Exposure Classification Project (ECP) was conducted to measure pollutant concentrations for common urban microenvironments (MEs) for use in evaluating the results of regulatory human exposure models. Nearly 500 sets of measurements were made in three Los Angeles County communities during fall 2008, winter 2009, and summer 2009. MEs included in-vehicle, near-road, outdoor and indoor locations accessible to the general public. Contemporaneous 1- to 15-min average personal breathing zone concentrations of carbon monoxide (CO), carbon dioxide (CO2), volatile organic compounds (VOCs), nitric oxide (NO), nitrogen oxides (NO(x)), particulate matter (< 2.5 microm diameter; PM2.5) mass, ultrafine particle (UFP; < 100 nm diameter) number black carbon (BC), speciated HAPs (e.g, benzene, toluene, ethylbenzene, xylenes [BTEX], 1,3-butadiene), and ozone (O3) were measured continuously. In-vehicle and inside/outside measurements were made in various passenger vehicle types and in public buildings to estimate penetration or infiltration factors. A large fraction of the observed pollutant concentrations for on-road MEs, especially near diesel trucks, was unrelated to ambient measurements at nearby monitors. Comparisons of ME concentrations estimated using the median ME/ambient ratio versus regression slopes and intercepts indicate that the regression approach may be more accurate for on-road MEs. Ranges in the ME/ambient ratios among ME categories were generally

  10. Air Pollution in China: Mapping of Concentrations and Sources

    PubMed Central

    Rohde, Robert A.; Muller, Richard A.

    2015-01-01

    China has recently made available hourly air pollution data from over 1500 sites, including airborne particulate matter (PM), SO2, NO2, and O3. We apply Kriging interpolation to four months of data to derive pollution maps for eastern China. Consistent with prior findings, the greatest pollution occurs in the east, but significant levels are widespread across northern and central China and are not limited to major cities or geologic basins. Sources of pollution are widespread, but are particularly intense in a northeast corridor that extends from near Shanghai to north of Beijing. During our analysis period, 92% of the population of China experienced >120 hours of unhealthy air (US EPA standard), and 38% experienced average concentrations that were unhealthy. China’s population-weighted average exposure to PM2.5 was 52 μg/m3. The observed air pollution is calculated to contribute to 1.6 million deaths/year in China [0.7–2.2 million deaths/year at 95% confidence], roughly 17% of all deaths in China. PMID:26291610

  11. Air Pollution in China: Mapping of Concentrations and Sources.

    PubMed

    Rohde, Robert A; Muller, Richard A

    2015-01-01

    China has recently made available hourly air pollution data from over 1500 sites, including airborne particulate matter (PM), SO2, NO2, and O3. We apply Kriging interpolation to four months of data to derive pollution maps for eastern China. Consistent with prior findings, the greatest pollution occurs in the east, but significant levels are widespread across northern and central China and are not limited to major cities or geologic basins. Sources of pollution are widespread, but are particularly intense in a northeast corridor that extends from near Shanghai to north of Beijing. During our analysis period, 92% of the population of China experienced >120 hours of unhealthy air (US EPA standard), and 38% experienced average concentrations that were unhealthy. China's population-weighted average exposure to PM2.5 was 52 μg/m3. The observed air pollution is calculated to contribute to 1.6 million deaths/year in China [0.7-2.2 million deaths/year at 95% confidence], roughly 17% of all deaths in China.

  12. Reproducibility of measurements of trace gas concentrations in expired air.

    PubMed

    Strocchi, A; Ellis, C; Levitt, M D

    1991-07-01

    Measurement of the pulmonary excretion of trace gases has been used as a simple means of assessing metabolic reactions. End alveolar trace gas concentration, rather than excretory rate, is usually measured. However, the reproducibility of this measurement has received little attention. In 17 healthy subjects, duplicate collections of alveolar air were obtained within 1 minute of each other using a commercially available alveolar air sampler. The concentrations of hydrogen, methane, carbon monoxide, and carbon dioxide were measured. When the subject received no instruction on how to expire into the device, a difference of 28% +/- 19% (1SD) was found between duplicate determinations of hydrogen. Instructing the subjects to avoid hyperventilation or to inspire maximally and exhale immediately resulted in only minor reduction in variability. However, a maximal inspiration held for 15 seconds before exhalation reduced the difference to a mean of 9.6% +/- 8.0%, less than half that observed with the other expiratory techniques. Percentage difference of methane measurements with the four different expiratory techniques yielded results comparable to those obtained for hydrogen. In contrast, percentage differences for carbon monoxide measurements were similar for all expiratory techniques. When normalized to a PCO2 of 5%, the variability of hydrogen measurements with the breath-holding technique was reduced to 6.8% +/- 4.7%, a value significantly lower than that obtained with the other expiratory methods. This study suggests that attention to the expiratory technique could improve the accuracy of tests using breath hydrogen measurements.

  13. Catalytic wet air oxidation of high concentration pharmaceutical wastewater.

    PubMed

    Zhan, Wei; Wang, Xiaocong; Li, Daosheng; Ren, Yongzheng; Liu, Dongqi; Kang, Jianxiong

    2013-01-01

    In this study, we investigated the pretreatment of a high concentration pharmaceutical wastewater by catalytic wet air oxidation (CWAO) process. Different experiments were conducted to investigate the effects of the catalyst type, operating temperature, initial system pH, and oxygen partial pressure on the oxidation of the wastewater. Results show that the catalysts prepared by the co-precipitation method have better catalytic activity compared to others. Chemical oxygen demand (COD) conversion increased with the increase in temperature from 160 to 220 °C and decreased with the increase in pH. Moreover, the effect of the oxygen partial pressure on the COD conversion was significant only during the first 20 min of the reaction. Furthermore, the biodegradability of the wastewater improved greatly after CWAO, the ratio of BOD5/COD increased less than 0.1-0.75 when treated at 220 °C (BOD: biochemical oxygen demand).

  14. Direct Capture of CO2 from Ambient Air.

    PubMed

    Sanz-Pérez, Eloy S; Murdock, Christopher R; Didas, Stephanie A; Jones, Christopher W

    2016-10-12

    The increase in the global atmospheric CO2 concentration resulting from over a century of combustion of fossil fuels has been associated with significant global climate change. With the global population increase driving continued increases in fossil fuel use, humanity's primary reliance on fossil energy for the next several decades is assured. Traditional modes of carbon capture such as precombustion and postcombustion CO2 capture from large point sources can help slow the rate of increase of the atmospheric CO2 concentration, but only the direct removal of CO2 from the air, or "direct air capture" (DAC), can actually reduce the global atmospheric CO2 concentration. The past decade has seen a steep rise in the use of chemical sorbents that are cycled through sorption and desorption cycles for CO2 removal from ultradilute gases such as air. This Review provides a historical overview of the field of DAC, along with an exhaustive description of the use of chemical sorbents targeted at this application. Solvents and solid sorbents that interact strongly with CO2 are described, including basic solvents, supported amine and ammonium materials, and metal-organic frameworks (MOFs), as the primary classes of chemical sorbents. Hypothetical processes for the deployment of such sorbents are discussed, as well as the limited array of technoeconomic analyses published on DAC. Overall, it is concluded that there are many new materials that could play a role in emerging DAC technologies. However, these materials need to be further investigated and developed with a practical sorbent-air contacting process in mind if society is to make rapid progress in deploying DAC as a means of mitigating climate change.

  15. Decoupled active contour (DAC) for boundary detection.

    PubMed

    Mishra, Akshaya Kumar; Fieguth, Paul W; Clausi, David A

    2011-02-01

    The accurate detection of object boundaries via active contours is an ongoing research topic in computer vision. Most active contours converge toward some desired contour by minimizing a sum of internal (prior) and external (image measurement) energy terms. Such an approach is elegant, but suffers from a slow convergence rate and frequently misconverges in the presence of noise or complex contours. To address these limitations, a decoupled active contour (DAC) is developed which applies the two energy terms separately. Essentially, the DAC consists of a measurement update step, employing a Hidden Markov Model (HMM) and Viterbi search, and then a separate prior step, which modifies the updated curve based on the relative strengths of the measurement uncertainty and the nonstationary prior. By separating the measurement and prior steps, the algorithm is less likely to misconverge; furthermore, the use of a Viterbi optimizer allows the method to converge far more rapidly than energy-based iterative solvers. The results clearly demonstrate that the proposed approach is robust to noise, can capture regions of very high curvature, and exhibits limited dependence on contour initialization or parameter settings. Compared to five other published methods and across many image sets, the DAC is found to be faster with better or comparable segmentation accuracy.

  16. IMPACT OF AN OZONE GENERATOR AIR CLEANER ON STYRENE CONCENTRATIONS IN AN INDOOR AIR QUALITY RESEARCH CHAMBER

    EPA Science Inventory

    The paper gives results of an investigation of the impact of an ozone generator air cleaner on vapor-phase styrene concentrations in a full-scale indoor air quality test chamber. The time history of the concentrations of styrene and ozone is well predicted by a simulation model u...

  17. 10 CFR 835.209 - Concentrations of radioactive material in air.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 10 Energy 4 2010-01-01 2010-01-01 false Concentrations of radioactive material in air. 835.209... External Exposure § 835.209 Concentrations of radioactive material in air. (a) The derived air... exposures to airborne radioactive material. (b) The estimation of internal dose shall be based on...

  18. Opening Comments: SciDAC 2008

    NASA Astrophysics Data System (ADS)

    Strayer, Michael

    2008-07-01

    Welcome to Seattle and the 2008 SciDAC Conference. This conference, the fourth in the series, is a continuation of the PI meetings we first began under SciDAC-1. I would like to start by thanking the organizing committee, and Rick Stevens in particular, for organizing this year's meeting. This morning I would like to look briefly at SciDAC, to give you a brief history of SciDAC and also look ahead to see where we plan to go over the next few years. I think the best description of SciDAC, at least the simulation part, comes from a quote from Dr Ray Orbach, DOE's Under Secretary for Science and Director of the Office of Science. In an interview that appeared in the SciDAC Review magazine, Dr Orbach said, `SciDAC is unique in the world. There isn't any other program like it anywhere else, and it has the remarkable ability to do science by bringing together physical scientists, mathematicians, applied mathematicians, and computer scientists who recognize that computation is not something you do at the end, but rather it needs to be built into the solution of the very problem that one is addressing'. Of course, that is extended not just to physical scientists, but also to biological scientists. This is a theme of computational science, this partnership among disciplines, which goes all the way back to the early 1980s and Ken Wilson. It's a unique thread within the Department of Energy. SciDAC-1, launched around the turn of the millennium, created a new generation of scientific simulation codes. It advocated building out mathematical and computing system software in support of science and a new collaboratory software environment for data. The original concept for SciDAC-1 had topical centers for the execution of the various science codes, but several corrections and adjustments were needed. The ASCR scientific computing infrastructure was also upgraded, providing the hardware facilities for the program. The computing facility that we had at that time was the big 3

  19. A METHOD OF ASSESSING AIR TOXICS CONCENTRATIONS IN URBAN AREAS USING MOBILE PLATFORM MEASUREMENTS

    EPA Science Inventory

    The objective of this paper is to demonstrate an approach to characterize the spatial variability in ambient air concentrations using mobile platform measurements. This approach may be useful for air toxic assessments in Environmental Justice applications, epidemiological studies...

  20. New User Support in the University Network with DACS Scheme

    ERIC Educational Resources Information Center

    Odagiri, Kazuya; Yaegashi, Rihito; Tadauchi, Masaharu; Ishii, Naohiro

    2007-01-01

    Purpose: The purpose of this paper is to propose and examine the new user support in university network. Design/methodology/approach: The new user support is realized by use of DACS (Destination Addressing Control System) Scheme which manages a whole network system through communication control on a client computer. This DACS Scheme has been…

  1. Method of glitch reduction in DAC with weight redundancy

    NASA Astrophysics Data System (ADS)

    Azarov, Olexiy D.; Murashchenko, Olexander G.; Chernyak, Olexander I.; Smolarz, Andrzej; Kashaganova, Gulzhan

    2015-12-01

    The appearance of glitches in digital-to-analog converters leads to significant limitations of conversion accuracy and speed, which is critical for DAC and limits their usage. This paper researches the possibility of using the redundant positional number system in order to reduce glitches in DAC. There had been described the usage pattern of number systems with fractional digit weights of bits as well as with the whole number weights of bits. Hereafter there had been suggested the algorithm for glitches reduction in the DAC generation mode of incessant analogue signal. There had also been estimated the efficiency of weight redundancy application with further presentation of the most efficient parameters of number systems. The paper describes a block diagram of a low-glitch DAC based on Fibonacci codes. The simulation results prove the feasibility of weight redundancy application and show a significant reduction of glitches in DAC in comparison with the classical binary system.

  2. Global Ammonia Concentrations Seen by the 13-years AIRS Measurements

    NASA Astrophysics Data System (ADS)

    Warner, Juying; Wei, Zigang; Larrabee Strow, L.; Dickerson, Russell; Nowak, John; Wang, Yuxuan

    2016-04-01

    Ammonia is an integral part of the nitrogen cycle and is projected to be the largest single contributor to each of acidification, eutrophication and secondary particulate matter in Europe by 2020 (Sutton et al., 2008). The impacts of NH3 also include: aerosol production affecting global radiative forcing, increases in emissions of the greenhouse gases nitrous oxide (N2O) and methane (CH4), and modification of the transport and deposition patterns of SO2 and NOx. Therefore, monitoring NH3 global distribution of sources is vitally important to human health with respect to both air and water quality and climate change. We have developed new daily and global ammonia (NH3) products from AIRS hyperspectral measurements. These products add value to AIRS's existing products that have made significant contributions to weather forecasts, climate studies, and air quality monitoring. With longer than 13 years of data records, these measurements have been used not only for daily monitoring purposes but also for inter-annual variability and short-term trend studies. We will discuss the global NH3 emission sources from biogenic and anthropogenic activities over many emission regions captured by AIRS. We will focus their variability in the last 13 years.

  3. Uvaridacols E-H, highly oxygenated antiausterity agents from Uvaria dac.

    PubMed

    Awale, Suresh; Ueda, Jun-ya; Athikomkulchai, Sirivan; Dibwe, Dya Fita; Abdelhamed, Sherif; Yokoyama, Satoru; Saiki, Ikuo; Miyatake, Ryuta

    2012-11-26

    Chemical investigation of the stems of Uvaria dac yielded four new highly oxygenated cyclohexene derivatives named uvaridacols E-H (1-4). Their structures were established through NMR and circular dichroism spectroscopic analysis. Uvaridacols E (1), F (2), and H (4) displayed weak preferential cytotoxicity against PANC-1 human pancreatic cancer cells under nutrition-deprived conditions in a concentration-dependent manner, without causing toxicity in normal nutrient-rich conditions.

  4. Time variations of 222Rn concentration and air exchange rates in a Hungarian cave.

    PubMed

    Nagy, Hedvig Éva; Szabó, Zsuzsanna; Jordán, Gyozo; Szabó, Csaba; Horváth, Akos; Kiss, Attila

    2012-09-01

    A long-term radon concentration monitoring was carried out in the Pál-völgy cave, Budapest, Hungary, for 1.5 years. Our major goal was to determine the time dependence of the radon concentration in the cave to characterise the air exchange and define the most important environmental parameters that influence the radon concentration inside the cave. The radon concentration in the cave air was measured continuously by an AlphaGuard radon monitor, and meteorological parameters outside the cave were collected simultaneously. The air's radon concentration in the cave varied between 104 and 7776 Bq m(-3), the annual average value was 1884±85 Bq m(-3). The summer to winter radon concentration ratio was as high as 21.8. The outside air temperature showed the strongest correlation with the radon concentration in the cave, the correlation coefficient (R) was 0.76.

  5. SciDAC Institute for Ultrascale Visualization

    SciTech Connect

    Humphreys, Grigori R.

    2008-09-30

    The Institute for Ultrascale Visualization aims to address visualization needs of SciDAC science domains, including research topics in advanced scientific visualization architectures, algorithms, and interfaces for understanding large, complex datasets. During the current project period, the focus of the team at the University of Virginia has been interactive remote rendering for scientific visualization. With high-performance computing resources enabling increasingly complex simulations, scientists may desire to interactively visualize huge 3D datasets. Traditional large-scale 3D visualization systems are often located very close to the processing clusters, and are linked to them with specialized connections for high-speed rendering. However, this tight coupling of processing and display limits possibilities for remote collaboration, and prohibits scientists from using their desktop workstations for data exploration. In this project, we are developing a client/server system for interactive remote 3D visualization on desktop computers.

  6. “Modeling Trends in Air Pollutant Concentrations over the ...

    EPA Pesticide Factsheets

    Regional model calculations over annual cycles have pointed to the need for accurately representing impacts of long-range transport. Linking regional and global scale models have met with mixed success as biases in the global model can propagate and influence regional calculations and often confound interpretation of model results. Since transport is efficient in the free-troposphere and since simulations over Continental scales and annual cycles provide sufficient opportunity for “atmospheric turn-over”, i.e., exchange between the free-troposphere and the boundary-layer, a conceptual framework is needed wherein interactions between processes occurring at various spatial and temporal scales can be consistently examined. The coupled WRF-CMAQ model is expanded to hemispheric scales and model simulations over period spanning 1990-current are analyzed to examine changes in hemispheric air pollution resulting from changes in emissions over this period. The National Exposure Research Laboratory (NERL) Atmospheric Modeling and Analysis Division (AMAD) conducts research in support of EPA mission to protect human health and the environment. AMAD research program is engaged in developing and evaluating predictive atmospheric models on all spatial and temporal scales for forecasting the air quality and for assessing changes in air quality and air pollutant exposures, as affected by changes in ecosystem management and regulatory decisions. AMAD is responsible for pr

  7. Opening Comments: SciDAC 2009

    NASA Astrophysics Data System (ADS)

    Strayer, Michael

    2009-07-01

    Welcome to San Diego and the 2009 SciDAC conference. Over the next four days, I would like to present an assessment of the SciDAC program. We will look at where we've been, how we got to where we are and where we are going in the future. Our vision is to be first in computational science, to be best in class in modeling and simulation. When Ray Orbach asked me what I would do, in my job interview for the SciDAC Director position, I said we would achieve that vision. And with our collective dedicated efforts, we have managed to achieve this vision. In the last year, we have now the most powerful supercomputer for open science, Jaguar, the Cray XT system at the Oak Ridge Leadership Computing Facility (OLCF). We also have NERSC, probably the best-in-the-world program for productivity in science that the Office of Science so depends on. And the Argonne Leadership Computing Facility offers architectural diversity with its IBM Blue Gene/P system as a counterbalance to Oak Ridge. There is also ESnet, which is often understated—the 40 gigabit per second dual backbone ring that connects all the labs and many DOE sites. In the President's Recovery Act funding, there is exciting news that ESnet is going to build out to a 100 gigabit per second network using new optical technologies. This is very exciting news for simulations and large-scale scientific facilities. But as one noted SciDAC luminary said, it's not all about the computers—it's also about the science—and we are also achieving our vision in this area. Together with having the fastest supercomputer for science, at the SC08 conference, SciDAC researchers won two ACM Gordon Bell Prizes for the outstanding performance of their applications. The DCA++ code, which solves some very interesting problems in materials, achieved a sustained performance of 1.3 petaflops, an astounding result and a mark I suspect will last for some time. The LS3DF application for studying nanomaterials also required the development of a

  8. Estimation of the dominant degrees of freedom for air pollutant concentration data: Applications to ozone measurements

    NASA Astrophysics Data System (ADS)

    Li, I.-Fen; Biswas, Pratim; Islam, Shafiqul

    A nonlinear dynamic analysis of air quality data has been performed and applied to a time series of ozone concentration data from the Cincinnati air shed. The analysis helped to identify the nature of the dynamics of the ozone concentrations and determine the number of degrees of freedom or dimensionality of the system. Results indicated that the dimensionality of the system was 3, indicating that there are three dominant variables affecting ozone concentration levels in the Cincinnati air shed. Statistical analysis was performed to infer that NO was correlated to ozone concentration levels.

  9. The concentrations of culturable microorganisms in relation to particulate matter in urban air

    NASA Astrophysics Data System (ADS)

    Haas, D.; Galler, H.; Luxner, J.; Zarfel, G.; Buzina, W.; Friedl, H.; Marth, E.; Habib, J.; Reinthaler, F. F.

    2013-02-01

    The ambient air consists not only of gases but also of bioaerosols and particulate matter. The concentrations of particulate matter in relation to the culturable microorganisms in the urban ambient air and their dependence on air temperature and relative humidity were investigated. The seasonal distribution of particles sizes, the concentrations of aerobic mesophilic bacteria and xerophilic fungi in the air were evaluated. Moreover, the identification of the fungal genera Cladosporium, Aspergillus and Penicillium were conducted. Within one year at 177 days particle and microorganism concentrations in the ambient air were recorded in the city centre of Graz/Austria. The results show that the concentrations of fine particles and coarse particles were the highest in winter and decreased continuously to a minimum in the summer months depending on temperature and air humidity. The concentrations of xerophilic fungi showed no correlation to the different particle concentrations. The spore concentrations of Cladosporium spp. showed the same results of xerophilic fungi whereas the genera Penicillium and Aspergillus increased with the increase of fine particles. The concentrations of mesophilic bacteria were positively correlated with all particle counts. The maximum mesophilic bacteria concentrations were found in the winter months. Further studies are required to evaluate the concentrations of specific microorganisms in the natural environment in relation to the particulate matter.

  10. A method for determination of methyl chloride concentration in air trapped in ice cores.

    PubMed

    Saito, Takuya; Yokouchi, Yoko; Aoki, Shuji; Nakazawa, Takakiyo; Fujii, Yoshiyuki; Watanabe, Okitsugu

    2006-05-01

    A method for measuring the concentration of methyl chloride (CH3Cl) in air trapped in an ice core was developed. The method combines the air extraction by milling the ice core samples under vacuum and the analysis of the extracted air with a cryogenic preconcentration/gas chromatograph/mass spectrometry system. The method was applied to air from Antarctic ice core samples estimated to have been formed in the pre-industrial and/or early industrial periods. The overall precision of the method deduced from duplicate ice core analyses was estimated to be better than +/-20 pptv. The measured CH3Cl concentration of 528+/-26 pptv was similar to the present-day concentration in the remote atmosphere as well as the CH3Cl concentration over the past 300 years obtained from Antarctic firn air and ice core analyses.

  11. AN INDOOR PESTICIDE AIR AND SURFACE CONCENTRATION MODEL

    EPA Science Inventory

    A thorough assessment of human exposure to environmental chemicals requires consideration of all processes in the sequence from source to dose. For assessment of exposure to pesticides following their use indoors, data and models are needed to estimate pesticide concentrations...

  12. Measuring Concentrations of Particulate 140La in the Air

    SciTech Connect

    Okada, Colin E.; Kernan, Warnick; Keillor, Martin; Kirkham, Randy; Sorom, Rich D.; Van Etten, Don M.

    2016-01-01

    This article discusses deployment of air-samplers to measure the concentration of radioactive material in the air during the Full-Scale Radiological Dispersal Device experiments. Positioned 100-600 meters downwind of the release point, the filters were collected immediately and analyzed in a field laboratory. The article discusses quantities for total activity collected on the air filters as well as additional information to compute the average or integrated air concentrations. In the case of a public emergency, this type of information would be important for decision makers and responders.

  13. Daily and seasonal variations in radon activity concentration in the soil air.

    PubMed

    Műllerová, Monika; Holý, Karol; Bulko, Martin

    2014-07-01

    Radon activity concentration in the soil air in the area of Faculty of Mathematics, Physics and Informatics (FMPI) in Bratislava, Slovak Republic, has been continuously monitored since 1994. Long-term measurements at a depth of 0.8 m and short-term measurements at a depth of 0.4 m show a high variability in radon activity concentrations in the soil. The analysis of the data confirms that regular daily changes in radon activity concentration in the soil air depend on the daily changes in atmospheric pressure. It was also found that the typical annual courses of the radon activity concentration in the soil air (with summer minima and winter maxima) were disturbed by mild winter and heavy summer precipitation. Influence of precipitation on the increase in the radon activity concentration in the soil air was observed at a depth of 0.4 m and subsequently at a depth of 0.8 m.

  14. EFFECTS OF METAL COMPONENTS IN CONCENTRATED AMBIENT AIR PARTICLES ON PULMONARY INJURY

    EPA Science Inventory

    EFFECTS OF METAL COMPONENTS IN CONCENTRATED AMBIENT AIR PARTICLES ON PULMONARY INJURY. Yuh-Chin Huang, Jackie Stonehuerner, Jackie Carter, Andrew J. Ghio, Robert B. Devlin. NHEERL, US EPA, RTP, NC.
    The mechanisms for cardiopulmonary morbidity associated with exposure to air po...

  15. Analysis of Mobile Source Air Toxics (MSATS)–Near-Road VOC and CarbonylConcentrations

    EPA Science Inventory

    This presentation examines data from a year-long study of measured near-road mobile source air toxic (MSAT) concentrations and compares these data with modeled 2005 National Air Toxic Assessment (NATA) results. Field study measurements were collected during a field campaign in ...

  16. AGE AND STRAIN INFLUENCES ON LUNG RESPONSES TO CONCENTRATED AIR PARTICULATES (CAPS) IN RODENTS

    EPA Science Inventory

    Asthma, an inflammatory airways disease, is an urgent health problem. Recent epidemiologic studies have demonstrated positive associations between ambient air particulate matter concentrations and daily respiratory morbidity ? including exacerbations of asthma. Of note, elderly i...

  17. Concentrations in air of organobromine, organochlorine and organophosphate flame retardants in Toronto, Canada

    NASA Astrophysics Data System (ADS)

    Shoeib, Mahiba; Ahrens, Lutz; Jantunen, Liisa; Harner, Tom

    2014-12-01

    Concentrations of organobromine (BFRs), organochlorine (CFRs) and organophosphate esters flame retardants and plasticizers (PFRs) in air were monitored for over one year at an urban site in Toronto, Canada during 2010-2011. The mean value for polybrominated diphenyl ethers (BDEs) (gas + particle phase) was 38 pg/m3 with BDE-47 and BDE-99 as the dominant congeners. The mean concentrations in air for ∑non-BDE (BFRs and CFRs), was 9.6 pg/m3 - about four times lower than the BDEs. The brominated FRs: TBP-AE, BTBPE, EH-TBB, BEH-TEBP and the chlorinated syn- and anti-DP were detected frequently, ranging from 87% to 96%. Highest concentrations in air among all flame retardant classes were observed for the Σ-PFRs. The yearly mean concentration in air for ΣPFRs was 2643 pg/m3 with detection frequency higher than 80%. Except for TBP-AE and b- DBE-DBCH, non-BDEs (BFRs, CFRs and PFRs) were mainly associated with the particle phase. BDE concentrations in air were positively correlated with temperature indicating that volatilization from local sources was an important factor controlling levels in air. This correlation did not hold for most BFRs, CFRs and PFRs which were mainly on particles. For these compounds, air concentrations in Toronto are likely related to emissions from point sources and advective inputs. This study highlights the importance of urban air monitoring for FRs. Urban air can be considered a sentinel for detecting changes in the use and application of FRs in commercial products.

  18. USING THE AIR QUALITY MODEL TO ANALYZE THE CONCENTRATIONS OF AIR TOXICS OVER THE CONTINENTAL U.S.

    EPA Science Inventory

    The U.S. Environmental Protection Agency is examining the concentrations and deposition of hazardous air pollutants (HAPs), which include a large number of chemicals, ranging from non reactive (i.e. carbon tetrachloride) to reactive (i.e. formaldehyde), exist in gas, aqueous, and...

  19. Trend and climate signals in seasonal air concentration of organochlorine pesticides over the Great Lakes

    NASA Astrophysics Data System (ADS)

    Gao, Hong; Ma, Jianmin; Cao, Zuohao; Dove, Alice; Zhang, Lisheng

    2010-08-01

    Following worldwide bans or restrictions, the atmospheric level of many organochlorine pesticides (OCPs) over the Great Lakes exhibited a decreasing trend since the 1980s in various environmental compartments. Atmospheric conditions also influence variation and trend of OCPs. In the present study a nonparametric Mann-Kendall test with an additional process to remove the effect of temporal (serial) correlation was used to detect the temporal trend of OCPs in the atmosphere over the Great Lakes region and to examine the statistical significance of the trends. Using extended time series of measured air concentrations over the Great Lakes region from the Integrated Atmospheric Deposition Network, this study also revisits relationships between seasonal mean air concentration of OCPs and major climate variabilities in the Northern Hemisphere. To effectively extract climate signals from the temporal trend of air concentrations, we detrended air concentrations through removing their linear trend, which is driven largely by their respective half-lives in the atmosphere. The interannual variations of the extended time series show a good association with interannual climate variability, notably, the North Atlantic Oscillation (NAO) and the El Niño-Southern Oscillation. This study demonstrates that the stronger climate signals can be extracted from the detrended time series of air concentrations of some legacy OCPs. The detrended concentration time series also help to interpret, in addition to the connection with interannual variation of the NAO, the links between atmospheric concentrations of OCPs and decadal or interdecadal climate change.

  20. Predictors of Indoor Air Concentrations in Smoking and Non-Smoking Residences

    PubMed Central

    Héroux, Marie-Eve; Clark, Nina; Van Ryswyk, Keith; Mallick, Ranjeeta; Gilbert, Nicolas L.; Harrison, Ian; Rispler, Kathleen; Wang, Daniel; Anastassopoulos, Angelos; Guay, Mireille; MacNeill, Morgan; Wheeler, Amanda J.

    2010-01-01

    Indoor concentrations of air pollutants (benzene, toluene, formaldehyde, acetaldehyde, acrolein, nitrogen dioxide, particulate matter, elemental carbon and ozone) were measured in residences in Regina, Saskatchewan, Canada. Data were collected in 106 homes in winter and 111 homes in summer of 2007, with 71 homes participating in both seasons. In addition, data for relative humidity, temperature, air exchange rates, housing characteristics and occupants’ activities during sampling were collected. Multiple linear regression analysis was used to construct season-specific models for the air pollutants. Where smoking was a major contributor to indoor concentrations, separate models were constructed for all homes and for those homes with no cigarette smoke exposure. The housing characteristics and occupants’ activities investigated in this study explained between 11% and 53% of the variability in indoor air pollutant concentrations, with ventilation, age of home and attached garage being important predictors for many pollutants. PMID:20948949

  1. Evolution of HTO concentrations in soil, vegetation and air during an experimental chronic HT release

    SciTech Connect

    Davis, P.A.; Galeriu, D.C.; Spencer, F.S.; Amiro, B.D.

    1995-10-01

    A small experimental plot was continuously exposed to elevated levels of HT in air over a 12-day period to study the build up and steady-state concentrations of HTO in the environment. HTO concentrations in soil, vegetation and air all showed similar dynamics, increasing gradually over time with temporary decreases during and following rainfall. The relative magnitudes of the soil, vegetation and air concentrations depended on the height at which the air and vegetation were sampled, the depth at which the soil sample was taken and the soil depth over which the plants drew their transpiration water. The system was at or near steady-state in the last two or three days of the release. When averaged over an eight day interval that included periods of rain, the ratios of HTO concentration in soil, foliage and air moisture to HT concentration in air (measured 20 cm above the ground) were typically 0.0014, 0.0010 and 0.0011 (Bq/mL)/(Bq/m{sup 3}) for a cultivated field. 10 refs., 7 figs.

  2. An assessment of ozone concentrations within and near the Lake Tahoe Air Basin

    NASA Astrophysics Data System (ADS)

    Dolislager, Leon J.; VanCuren, Richard; Pederson, James R.; Lashgari, Ash; McCauley, Eileen

    2012-01-01

    The Lake Tahoe Atmospheric Deposition Study (LTADS) was conducted by the Air Resources Board of the State of California (CARB) primarily to generate refined estimates of the atmospheric deposition of nitrogen, phosphorous, and particulate matter directly to Lake Tahoe, which straddles the border between the states of California and Nevada near Reno, Nevada. The enhanced air quality monitoring during LTADS also included ozone measurements, which yielded additional insights into atmospheric processes and the role of transport in determining ozone concentrations within the Lake Tahoe Air Basin. The Lake Tahoe Air Basin is located generally downwind of air basins with major emissions of ozone precursors (e.g., VOCs, NOx), capable of generating significant ozone concentrations. Furthermore, vegetation on the western slope of the Sierra Nevada contribute biogenic organic compounds to the air mass. Ozone concentrations within the Tahoe Basin infrequently exceed the local 1-h threshold set to protect forest health (0.08 ppm) and the California 8-h ambient air quality standard (0.070 ppm). A concern then is the potential contribution of regional emission sources to the ozone concentrations observed in the Tahoe Basin. The ozone data collected during LTADS helped to better characterize the relative contribution of local and regional pollution sources to ozone air quality within the Tahoe Basin. The data indicate potential 1- or 2-day intact transport on rare occasions but generally the mixing of the atmosphere over the Sierra Nevada disperses the anthropogenic ozone throughout the boundary layer, which is generally more than a kilometer or two deep during the day. The data analysis indicates that emissions from upwind air basins add to the atmospheric burden of ozone concentrations, raising the regional concentrations in the Sierra Nevada. Given the large background and upwind enhancements relative to the ambient air quality standards, the local contribution does not need to

  3. CONCENTRATED AMBIENT AIR PARTICLES INDUCE PULMONARY INFLAMMATION IN HEALTHY HUMAN VOLUNTEERS

    EPA Science Inventory


    We tested the hypothesis that exposure of healthy volunteers to concentrated ambient particles (CAPS) is associated with an influx of inflammatory cells into the lower respiratory tract. Thirty-eight volunteers were exposed to either filtered air or particles concentrated fro...

  4. COMPARISON OF MOLD CONCENTRATIONS IN INDOOR AND OUTDOOR AIR SAMPLED SIMULTANEOUSLY AND THEN QUANTIFIED BY MSQPCR

    EPA Science Inventory

    Mold specific quantitative PCR (MSQPCR) was used to measure the concentrations of the 36 mold species in indoor and outdoor air samples that were taken simultaneously for 48 hours in and around 17 homes in Cincinnati, Ohio. The total spore concentrations of 353 per m3...

  5. Modelling the impact of room temperature on concentrations of polychlorinated biphenyls (PCBs) in indoor air.

    PubMed

    Lyng, Nadja Lynge; Clausen, Per Axel; Lundsgaard, Claus; Andersen, Helle Vibeke

    2016-02-01

    Buildings contaminated with polychlorinated biphenyls (PCBs) are a health concern for the building occupants. Inhalation exposure is linked to indoor air concentrations of PCBs, which are known to be affected by indoor temperatures. In this study, a highly PCB contaminated room was heated to six temperature levels between 20 and 30 C, i.e. within the normal fluctuation of indoor temperatures, while the air exchange rate was constant. The steady-state air concentrations of seven PCBs were determined at each temperature level. A model based on Clausius-Clapeyron equation, ln(P) = -ΔH/RT + a(0), where changes in steady-state air concentrations in relation to temperature, was tested. The model was valid for PCB-28, PCB-52 and PCB-101; the four other congeners were sporadic or non-detected. For each congener, the model described a large proportion (R(2)>94%) of the variation in indoor air PCB levels. The results showed that one measured concentration of PCB at a known steady-state temperature can be used to predict the steady-state concentrations at other temperatures under circumstances where e.g. direct sunlight does not influence temperatures and the air exchange rate is constant. The model was also tested on field data from a PCB remediation case in an apartment in another contaminated building complex where PCB concentrations and temperature were measured simultaneously and regularly throughout one year. The model fitted relatively well with the regression of measured PCB air concentrations, ln(P) vs. 1/T, at varying temperature between 16.3 and 28.2 °C, even though the measurements were carried out under uncontrolled environmental condition.

  6. Prediction of Air Pollutants Concentration Based on an Extreme Learning Machine: The Case of Hong Kong

    PubMed Central

    Zhang, Jiangshe; Ding, Weifu

    2017-01-01

    With the development of the economy and society all over the world, most metropolitan cities are experiencing elevated concentrations of ground-level air pollutants. It is urgent to predict and evaluate the concentration of air pollutants for some local environmental or health agencies. Feed-forward artificial neural networks have been widely used in the prediction of air pollutants concentration. However, there are some drawbacks, such as the low convergence rate and the local minimum. The extreme learning machine for single hidden layer feed-forward neural networks tends to provide good generalization performance at an extremely fast learning speed. The major sources of air pollutants in Hong Kong are mobile, stationary, and from trans-boundary sources. We propose predicting the concentration of air pollutants by the use of trained extreme learning machines based on the data obtained from eight air quality parameters in two monitoring stations, including Sham Shui Po and Tap Mun in Hong Kong for six years. The experimental results show that our proposed algorithm performs better on the Hong Kong data both quantitatively and qualitatively. Particularly, our algorithm shows better predictive ability, with R2 increased and root mean square error values decreased respectively. PMID:28125034

  7. Prediction of Air Pollutants Concentration Based on an Extreme Learning Machine: The Case of Hong Kong.

    PubMed

    Zhang, Jiangshe; Ding, Weifu

    2017-01-24

    With the development of the economy and society all over the world, most metropolitan cities are experiencing elevated concentrations of ground-level air pollutants. It is urgent to predict and evaluate the concentration of air pollutants for some local environmental or health agencies. Feed-forward artificial neural networks have been widely used in the prediction of air pollutants concentration. However, there are some drawbacks, such as the low convergence rate and the local minimum. The extreme learning machine for single hidden layer feed-forward neural networks tends to provide good generalization performance at an extremely fast learning speed. The major sources of air pollutants in Hong Kong are mobile, stationary, and from trans-boundary sources. We propose predicting the concentration of air pollutants by the use of trained extreme learning machines based on the data obtained from eight air quality parameters in two monitoring stations, including Sham Shui Po and Tap Mun in Hong Kong for six years. The experimental results show that our proposed algorithm performs better on the Hong Kong data both quantitatively and qualitatively. Particularly, our algorithm shows better predictive ability, with R 2 increased and root mean square error values decreased respectively.

  8. Derivation and implementation of an annual limit on intake and a derived air concentration value for uranium mill tailings.

    PubMed

    Reif, R H; Andrews, D W

    1995-06-01

    Monitoring workers and work areas at the Department of Energy Uranium Mill Tailings Remedial Action Project sites is complex because all radionuclides in the 238U and 235U decay chains may be present in an airborne uranium mill tailings matrix. Previous monitoring practices involved isotopic analysis of the air filter to determine the activity of each radionuclide of concern and comparing the results to the specified derived air concentration. The annual limit on intake and derived air concentration values have been derived here for the uranium mill tailings matrix to simplify the procedure for evaluation of air monitoring results and assessment of the need for individual monitoring. Implementation of the derived air concentration for uranium mill tailings involves analyzing air samples for long-lived gross alpha activity and comparing the activity concentration to the derived air concentration. Health physics decisions regarding assessment of airborne concentrations is more cost-effective because isotopic analysis of air samples is not necessary.

  9. Methods to reduce the CO(2) concentration of educational buildings utilizing internal ventilation by transferred air.

    PubMed

    Kalema, T; Viot, M

    2014-02-01

    The aim of this study is to develop internal ventilation by transferred air to achieve a good indoor climate with low energy consumption in educational buildings with constant air volume (CAV) ventilation. Both measurements of CO2 concentration and a multi-room calculation model are presented. The study analyzes how to use more efficiently the available spaces and the capacity of CAV ventilation systems in existing buildings and the impact this has on the indoor air quality and the energy consumption of the ventilation. The temperature differences can be used to create natural ventilation airflows between neighboring spaces. The behavior of temperature-driven airflows between rooms was studied and included in the calculation model. The effect of openings between neighboring spaces, such as doors or large apertures in the walls, on the CO2 concentration was studied in different classrooms. The air temperatures and CO2 concentrations were measured using a wireless, internet-based measurement system. The multi-room calculation model predicted the CO2 concentration in the rooms, which was then compared with the measured ones. Using transferred air between occupied and unoccupied spaces can noticeably reduce the total mechanical ventilation rates needed to keep a low CO2 concentration.

  10. Historical Occupational Trichloroethylene Air Concentrations Based on Inspection Measurements From Shanghai, China

    PubMed Central

    Friesen, Melissa C.; Locke, Sarah J.; Chen, Yu-Cheng; Coble, Joseph B.; Stewart, Patricia A.; Ji, Bu-Tian; Bassig, Bryan; Lu, Wei; Xue, Shouzheng; Chow, Wong-Ho; Lan, Qing; Purdue, Mark P.; Rothman, Nathaniel; Vermeulen, Roel

    2015-01-01

    Purpose: Trichloroethylene (TCE) is a carcinogen that has been linked to kidney cancer and possibly other cancer sites including non-Hodgkin lymphoma. Its use in China has increased since the early 1990s with China’s growing metal, electronic, and telecommunications industries. We examined historical occupational TCE air concentration patterns in a database of TCE inspection measurements collected in Shanghai, China to identify temporal trends and broad contrasts among occupations and industries. Methods: Using a database of 932 short-term, area TCE air inspection measurements collected in Shanghai worksites from 1968 through 2000 (median year 1986), we developed mixed-effects models to evaluate job-, industry-, and time-specific TCE air concentrations. Results: Models of TCE air concentrations from Shanghai work sites predicted that exposures decreased 5–10% per year between 1968 and 2000. Measurements collected near launderers and dry cleaners had the highest predicted geometric means (GM for 1986 = 150–190mg m−3). The majority (53%) of the measurements were collected in metal treatment jobs. In a model restricted to measurements in metal treatment jobs, predicted GMs for 1986 varied 35-fold across industries, from 11mg m−3 in ‘other metal products/repair’ industries to 390mg m–3 in ‘ships/aircrafts’ industries. Conclusions: TCE workplace air concentrations appeared to have dropped over time in Shanghai, China between 1968 and 2000. Understanding differences in TCE concentrations across time, occupations, and industries may assist future epidemiologic studies in China. PMID:25180291

  11. Programmable flux DACs in a Quantum Annealing Processor

    NASA Astrophysics Data System (ADS)

    Hoskinson, Emile M.; Altomare, Fabio; Berkeley, Andrew J.; Bunyk, Paul; Harris, Richard; Johnson, Mark W.; Lanting, Trevor M.; Tolkacheva, Elena; Perminov, Ilya; Uchaikin, Sergey; Whittaker, Jed D.

    2014-03-01

    Programming the D-Wave Two processor to solve a given problem involves adjustment of thousands of independent flux biases. This is accomplished with an array of 4480 on-chip digital-to-analog converters (DACs), addressed using 56 external lines. Each DAC comprises a superconducting loop and control circuitry that allows injection of a deterministic number of flux quanta, up to a maximum value determined by the device parameters and the addressing scheme. In-depth characterization is performed to determine DAC transfer-functions and the addressing levels needed for fast and reliable programming. In contrast with traditional single-flux-quanta (SFQ) circuitry, zero static power during programming is dissipated on-chip, allowing efficient operation at mK temperatures.

  12. Indoor air polychlorinated biphenyl concentrations in three communities along the Upper Hudson River, New York.

    PubMed

    Wilson, Lloyd R; Palmer, Patrick M; Belanger, Erin E; Cayo, Michael R; Durocher, Lorie A; Hwang, Syni-An A; Fitzgerald, Edward F

    2011-10-01

    Indoor air polychlorinated biphenyl (PCB) concentrations were measured in upstate New York as part of a nonoccupational exposure investigation. The adjacent study communities contain numerous sites of current and former PCB contamination, including two capacitor-manufacturing facilities. Indoor air PCB concentrations in the study area homes were not significantly different than in the comparison area homes. Total PCB concentrations in the study area homes ranged from 0.3 to 114.3 ng/m(3) (median 7.9). For the comparison area homes, concentrations ranged from 0.3 to 233.3 ng/m(3) (median 6.8). No correlations were found between PCB concentrations in indoor and outdoor air, with indoor concentrations generally 20 times higher than outdoor concentrations. Of the home characteristics cataloged, the presence of fluorescent lights was significantly associated with total PCB concentration in the study area only. The indoor PCB concentrations measured in this study are similar to those in other communities with known PCB-contaminated sites and similar to levels reported in other locations from the northeastern United States.

  13. Concentrations, sources and human health risk of inhalation exposure to air toxics in Edmonton, Canada.

    PubMed

    Bari, Md Aynul; Kindzierski, Warren B

    2017-04-01

    With concern about levels of air pollutants in recent years in the Capital Region of Alberta, an investigation of ambient concentrations, sources and potential human health risk of hazardous air pollutants (HAPs) or air toxics was undertaken in the City of Edmonton over a 5-year period (2009-2013). Mean concentrations of individual HAPs in ambient air including volatile organic compounds (VOCs), polycyclic aromatic hydrocarbons (PAHs) and trace metals ranged from 0.04 to 1.73 μg/m(3), 0.01-0.54 ng/m(3), and 0.05-3.58 ng/m(3), respectively. Concentrations of benzene, naphthalene, benzo(a)pyrene (BaP), arsenic, manganese and nickel were far below respective annual Alberta Ambient Air Quality Objectives. Carcinogenic and non-carcinogenic risk of air toxics were also compared with risk levels recommended by regulatory agencies. Positive matrix factorization identified six air toxics sources with traffic as the dominant contributor to total HAPs (4.33 μg/m(3), 42%), followed by background/secondary organic aerosol (SOA) (1.92 μg/m(3), 25%), fossil fuel combustion (0.92 μg/m(3), 11%). On high particulate air pollution event days, local traffic was identified as the major contributor to total HAPs compared to background/SOA and fossil fuel combustion. Carcinogenic risk values of traffic, background/SOA and metals industry emissions were above the USEPA acceptable level (1 × 10(-6)), but below a tolerable risk (1 × 10(-4)) and Alberta benchmark (1 × 10(-5)). These findings offer useful preliminary information about current ambient air toxics levels, dominant sources and their potential risk to public health; and this information can support policy makers in the development of appropriate control strategies if required.

  14. Modeling the Concentrations of On-Road Air Pollutants in Southern California

    PubMed Central

    Li, Lianfa; Wu, Jun; Hudda, Neelakshi; Sioutas, Constantinos; Fruin, Scott A.; Delfino, Ralph J.

    2014-01-01

    High concentrations of air pollutants on roadways, relative to ambient concentrations, contribute significantly to total personal exposure. Estimation of these exposures requires measurements or prediction of roadway concentrations. Our study develops, compares and evaluates linear regression and non-linear generalized additive models (GAMs) to estimate on-road concentrations of four key air pollutants, particle-bound polycyclic aromatic hydrocarbons (PB-PAH), particle number count (PNC), nitrogen oxides (NOx), and particulate matter with diameter <2.5 μm (PM2.5) using traffic, meteorology, and elevation variables. Critical predictors included wind speed and direction for all the pollutants, traffic-related variables for PB-PAH, PNC, and NOx, and air temperatures and relative humidity for PM2.5. GAMs explained 50%, 55%, 46%, and 71% of the variance for log or square-root transformed concentrations of PB-PAH, PNC, NOx, and PM2.5 respectively, an improvement of 5 to over 15% over the linear models. Accounting for temporal autocorrelation in the GAMs further improved the prediction, explaining 57-89% of the variance. We concluded that traffic and meteorological data are good predictors in estimating on-road traffic-related air pollutant concentrations and GAMs perform better for non-linear variables, such as meteorological parameters. PMID:23859442

  15. Modelling and analysis of ozone concentration by artificial intelligent techniques for estimating air quality

    NASA Astrophysics Data System (ADS)

    Taylan, Osman

    2017-02-01

    High ozone concentration is an important cause of air pollution mainly due to its role in the greenhouse gas emission. Ozone is produced by photochemical processes which contain nitrogen oxides and volatile organic compounds in the lower atmospheric level. Therefore, monitoring and controlling the quality of air in the urban environment is very important due to the public health care. However, air quality prediction is a highly complex and non-linear process; usually several attributes have to be considered. Artificial intelligent (AI) techniques can be employed to monitor and evaluate the ozone concentration level. The aim of this study is to develop an Adaptive Neuro-Fuzzy inference approach (ANFIS) to determine the influence of peripheral factors on air quality and pollution which is an arising problem due to ozone level in Jeddah city. The concentration of ozone level was considered as a factor to predict the Air Quality (AQ) under the atmospheric conditions. Using Air Quality Standards of Saudi Arabia, ozone concentration level was modelled by employing certain factors such as; nitrogen oxide (NOx), atmospheric pressure, temperature, and relative humidity. Hence, an ANFIS model was developed to observe the ozone concentration level and the model performance was assessed by testing data obtained from the monitoring stations established by the General Authority of Meteorology and Environment Protection of Kingdom of Saudi Arabia. The outcomes of ANFIS model were re-assessed by fuzzy quality charts using quality specification and control limits based on US-EPA air quality standards. The results of present study show that the ANFIS model is a comprehensive approach for the estimation and assessment of ozone level and is a reliable approach to produce more genuine outcomes.

  16. Effect of outside air ventilation rate on VOC concentrations and emissions in a call center

    SciTech Connect

    Hodgson, A.T.; Faulkner, D.; Sullivan, D.P.; DiBartolomeo, D.L.; Russell, M.L.; Fisk, W.J.

    2002-01-01

    A study of the relationship between outside air ventilation rate and concentrations of VOCs generated indoors was conducted in a call center. Ventilation rates were manipulated in the building's four air handling units (AHUs). Concentrations of VOCs in the AHU returns were measured on 7 days during a 13-week period. Indoor minus outdoor concentrations and emission factors were calculated. The emission factor data was subjected to principal component analysis to identify groups of co-varying compounds based on source type. One vector represented emissions of solvents from cleaning products. Another vector identified occupant sources. Direct relationships between ventilation rate and concentrations were not observed for most of the abundant VOCs. This result emphasizes the importance of source control measures for limiting VOC concentrations in buildings.

  17. Effects of the Deregulation on the Concentration of the Brazilian Air Transportation Industry

    NASA Technical Reports Server (NTRS)

    Guterres, Marcelo Xavier; Muller, Carlos

    2003-01-01

    This paper addresses the effects of the deregulation of the Brazilian air transportation industry in terms of the concentration of the market. We will show some metrics that are commonly used to study the concentration of the industry. This paper uses the Herfindhal- Hirschman Index. This index tends to zero in the competitive scenario, with a large number of small firms, and to one in case of a monopolistic scenario. The paper analyses the dynamics of the concentration of the Brazilian domestic air transportation market, in order to evaluate the effects of deregulation. We conclude that the Brazilian market presents oligopoly characteristics and aspects in its current structure that maintain the market concentrated in spite of the Deregulation measures adopted by the aeronautical authority. Keywords: Herfindhal-Hirschman Index, concentration, Deregulation

  18. Influence of indoor air conditions on radon concentration in a detached house.

    PubMed

    Akbari, Keramatollah; Mahmoudi, Jafar; Ghanbari, Mahdi

    2013-02-01

    Radon is released from soil and building materials and can accumulate in residential buildings. Breathing radon and radon progeny for extended periods hazardous to health and can lead to lung cancer. Indoor air conditions and ventilation systems strongly influence indoor radon concentrations. This paper focuses on effects of air change rate, indoor temperature and relative humidity on indoor radon concentrations in a one family detached house in Stockholm, Sweden. In this study a heat recovery ventilation system unit was used to control the ventilation rate and a continuous radon monitor (CRM) was used to measure radon levels. FLUENT, a computational fluid dynamics (CFD) software package was used to simulate radon entry into the building and air change rate, indoor temperature and relative humidity effects using a numerical approach. The results from analytical solution, measurements and numerical simulations showed that air change rate, indoor temperature and moisture had significant effects on indoor radon concentration. Increasing air change rate reduces radon level and for a specific air change rate (in this work Ach = 0.5) there was a range of temperature and relative humidity that minimized radon levels. In this case study minimum radon levels were obtained at temperatures between 20 and 22 °C and a relative humidity of 50-60%.

  19. Relationship between acetaldehyde concentration in mouth air and tongue coating volume

    PubMed Central

    YOKOI, Aya; MARUYAMA, Takayuki; YAMANAKA, Reiko; EKUNI, Daisuke; TOMOFUJI, Takaaki; KASHIWAZAKI, Haruhiko; YAMAZAKI, Yutaka; MORITA, Manabu

    2015-01-01

    Objective Acetaldehyde is the first metabolite of ethanol and is produced in the epithelium by mucosal ALDH, while higher levels are derived from microbial oxidation of ethanol by oral microflora such as Candida species. However, it is uncertain whether acetaldehyde concentration in human breath is related to oral condition or local production of acetaldehyde by oral microflora. The aim of this pilot study was to investigate the relationship between physiological acetaldehyde concentration and oral condition in healthy volunteers. Material and Methods Sixty-five volunteers (51 males and 14 females, aged from 20 to 87 years old) participated in the present study. Acetaldehyde concentration in mouth air was measured using a portable monitor. Oral examination, detection of oral Candida species and assessment of alcohol sensitivity were performed. Results Acetaldehyde concentration [median (25%, 75%)] in mouth air was 170.7 (73.5, 306.3) ppb. Acetaldehyde concentration in participants with a tongue coating status score of 3 was significantly higher than in those with a score of 1 (p<0.017). After removing tongue coating, acetaldehyde concentration decreased significantly (p<0.05). Acetaldehyde concentration was not correlated with other clinical parameters, presence of Candida species, smoking status or alcohol sensitivity. Conclusion Physiological acetaldehyde concentration in mouth air was associated with tongue coating volume. PMID:25760268

  20. Measured phenol concentrations in air and rain water samples collected near a wood preserving facility

    SciTech Connect

    Allen, S.K.; Allen, C.W.

    1995-12-31

    Phenol concentrations were determined in air and rain water samples collected downwind from a coal tar creosote wood preserving facility in Terre Haute, IN. Coal tar creosote is known to contain a large number of constituents and is composed chiefly of polycyclic aromatic hydrocarbons (PAH), phenols, and N-, S-, and O-heterocycles. Phenol was chosen as a marker compound for coal tar creosote emissions because it is present at a large mole fraction in coal tar creosote. Phenol was determined by HPLC with UV-Visible detection. Phenol in collected rain water samples was determined directly by HPLC after acidification and filtration. Phenol concentrations in collected air samples ranged from 4.1 to 15.7 {micro}g/m3 while rain water concentrations ranged from 7.9 to 28.2 {micro}g/L. Using a value for the thermodynamic Henry`s law constant of K{sub H} = 4.5 {times} 10{sup {minus}4} L atm/mole at 20 C for phenol and measured gas-phase phenol concentrations, even higher rain water concentrations would be expected if equilibrium was established. This indicates that the amount of phenol present in the air parcels sampled exceeded the amount that could be scavenged by rain drops under the conditions prevailing at the time of sampling. The values for phenol concentrations reported here are roughly two orders of magnitude higher than results from previous studies where phenol concentrations in air and rain water samples collected in urban areas were reported. It is likely that other more toxic constituents of coal tar creosote are also present at high concentrations in air parcels that receive emissions from wood treatment facilities.

  1. Lead-210 concentration in the air at Mt. Zeppelin, Ny-Ålesund, Svalbard

    NASA Astrophysics Data System (ADS)

    Paatero, Jussi; Hatakka, Juha; Holmén, Kim; Eneroth, Kristina; Viisanen, Yrjö

    High-volume aerosol particle samples have been collected onto glass fibre filters at Ny-Ålesund, Svalbard. The filters have been assayed for 210Pb by measuring the alpha particles of its in-grown daughter nuclide 210Po. The observed 210Pb activity concentrations at Mt. Zeppelin, Ny-Ålesund, Svalbard vary between 11 and 620 μBq/m 3 in 2001. The 25%, 50%, and 75% percentiles of the 210Pb activity concentrations at Mt. Zeppelin are 42, 83, and 220 μBq/m 3. The values are clearly lower than at Sodankylä, northern Finland with corresponding values of 100, 170, and 270 μBq/m 3. The arithmetic mean concentrations in 2001 were 144 and 245 μBq/m 3 at Ny-Ålesund and Sodankylä, respectively. The lowest 210Pb activity concentrations are found during summer both at Svalbard and in Finland. The highest concentrations occur in March-April at Svalbard. This differs from the seasonal behaviour of 210Pb in Finland, where the highest concentrations are usually observed in February-March. This 1-month difference between Svalbard and Finland may be related to the strength of solar radiation and its capability to cause vertical mixing of the air. Air mass back trajectory analysis shows that the lowest concentrations found at Svalbard are associated with air masses coming from the North Atlantic Ocean, Greenland and the Canadian Arctic. The highest concentrations are associated with air masses originating from northern Europe and Siberia, and during winter also in air masses coming from the central Arctic Ocean.

  2. Mitigating factors on air concentrations of radon emanating from different granite samples

    SciTech Connect

    Qari, T.M.; Mamoon, A.M.; Abdul-Fattah, A.F. )

    1991-11-01

    Continuous exposure to increased air concentrations of radon in living areas is to be avoided according to the Environmental Protection Agency (EPA) and several published reports. Radon concentrations in ambient air are influenced by several factors related to the nature of the radon source itself, environmental conditions, and the presence of mitigating factors, if any. In this study, crushed granite samples of different types, particle diameters, and moisture contents were compared in simplified test systems with regard to radon emanation from the samples. The effects of selected mitigating factors, namely, ventilation and different barriers to diffusion of emanated radon were determined.

  3. High Concentrations of Ozone Air Pollution on Mount Everest: Health Implications for Sherpa Communities and Mountaineers.

    PubMed

    Semple, John L; Moore, G W Kent; Koutrakis, Petros; Wolfson, Jack M; Cristofanelli, Paolo; Bonasoni, Paolo

    2016-12-01

    Semple, John L., G.W. Kent Moore, Petros Koutrakis, Jack M. Wolfson, Paolo Cristofanelli, and Paolo Bonasoni. High concentrations of ozone air pollution on Mount Everest: health implications for Sherpa communities and mountaineers. High Alt Med Biol. 17:365-369, 2016.-Introduction: Populations in remote mountain regions are increasingly vulnerable to multiple climate mechanisms that influence levels of air pollution. Few studies have reported on climate-sensitive health outcomes unique to high altitude ecosystems. In this study, we report on the discovery of high-surface ozone concentrations and the potential impact on health outcomes on Mount Everest and the high Himalaya.

  4. Sensory and chemical characterization of VOC emissions from building products: impact of concentration and air velocity

    NASA Astrophysics Data System (ADS)

    Knudsen, H. N.; Kjaer, U. D.; Nielsen, P. A.; Wolkoff, P.

    The emissions from five commonly used building products were studied in small-scale test chambers over a period of 50 days. The odor intensity was assessed by a sensory panel and the concentrations of selected volatile organic compounds (VOCs) of concern for the indoor air quality were measured. The building products were three floor coverings: PVC, floor varnish on beechwood parquet and nylon carpet on a latex foam backing; an acrylic sealant, and a waterborne wall paint on gypsum board. The impacts of the VOC concentration in the air and the air velocity over the building products on the odor intensity and on the emission rate of VOCs were studied. The emission from each building product was studied under two or three different area-specific ventilation rates, i.e. different ratios of ventilation rate of the test chamber and building product area in the test chamber. The air velocity over the building product samples was adjusted to different levels between 0.1 and 0.3 m s -1. The origin of the emitted VOCs was assessed in order to distinguish between primary and secondary emissions. The results show that it is reasonable after an initial period of up to 14 days to consider the emission rate of VOCs of primary origin from most building products as being independent of the concentration and of the air velocity. However, if the building product surface is sensitive to oxidative degradation, increased air velocity may result in increased secondary emissions. The odor intensity of the emissions from the building products only decayed modestly over time. Consequently, it is recommended to use building products which have a low impact on the perceived air quality from the moment they are applied. The odor indices (i.e. concentration divided by odor threshold) of primary VOCs decayed markedly faster than the corresponding odor intensities. This indicates that the secondary emissions rather than the primary emissions, are likely to affect the perceived air quality in the

  5. Preliminary assessment of BTEX concentrations in indoor air of residential buildings and atmospheric ambient air in Ardabil, Iran

    NASA Astrophysics Data System (ADS)

    Hazrati, Sadegh; Rostami, Roohollah; Farjaminezhad, Manoochehr; Fazlzadeh, Mehdi

    2016-05-01

    BTEX concentrations in indoor and outdoor air of 50 homes were studied in Ardabil city and their influencing parameters including; heating system, using gas stove and samovar, tobacco smoking, the floors in which the monitored homes were located, and kitchen plan were considered in the study. Risk assessment analysis was carried out with the obtained concentrations based on EPA IRIS reference doses. BTEX compounds were sampled by charcoal tubes and the samples were analyzed by a GC-FID. Concentrations of benzene (15.18 μg/m3 vs. 8.65 μg/m3), toluene (69.70 μg/m3 vs. 40.56 μg/m3), ethylbenzene (12.07 μg/m3 vs. 4.92 μg/m3) and xylene (48.08 μg/m3 vs. 7.44 μg/m3) in indoor air were significantly (p < 0.05) higher than the levels quantified for outdoor air. The obtained concentrations of benzene were considerably higher than the recommended value of 5 μg/m3 established by Iran environmental protection organization. Among the BTEX compounds, benzene (HQ = 0.51) and xylene (HQ = 0.47) had notable hazard quotient and were the main pollutants responsible for high hazard index in the monitored homes (HI = 1.003). The results showed considerably high cancer risk for lifetime exposure to the indoor (125 × 10-6) and outdoor (71 × 10-6) benzene. Indoor benzene concentrations in homes were significantly influenced by type of heating system, story, and natural gas appliances.

  6. [Estimation of average traffic emission factor based on synchronized incremental traffic flow and air pollutant concentration].

    PubMed

    Li, Run-Kui; Zhao, Tong; Li, Zhi-Peng; Ding, Wen-Jun; Cui, Xiao-Yong; Xu, Qun; Song, Xian-Feng

    2014-04-01

    On-road vehicle emissions have become the main source of urban air pollution and attracted broad attentions. Vehicle emission factor is a basic parameter to reflect the status of vehicle emissions, but the measured emission factor is difficult to obtain, and the simulated emission factor is not localized in China. Based on the synchronized increments of traffic flow and concentration of air pollutants in the morning rush hour period, while meteorological condition and background air pollution concentration retain relatively stable, the relationship between the increase of traffic and the increase of air pollution concentration close to a road is established. Infinite line source Gaussian dispersion model was transformed for the inversion of average vehicle emission factors. A case study was conducted on a main road in Beijing. Traffic flow, meteorological data and carbon monoxide (CO) concentration were collected to estimate average vehicle emission factors of CO. The results were compared with simulated emission factors of COPERT4 model. Results showed that the average emission factors estimated by the proposed approach and COPERT4 in August were 2.0 g x km(-1) and 1.2 g x km(-1), respectively, and in December were 5.5 g x km(-1) and 5.2 g x km(-1), respectively. The emission factors from the proposed approach and COPERT4 showed close values and similar seasonal trends. The proposed method for average emission factor estimation eliminates the disturbance of background concentrations and potentially provides real-time access to vehicle fleet emission factors.

  7. Comparison of mold concentrations quantified by MSQPCR in indoor and outdoor air sampled simultaneously

    SciTech Connect

    Meklin, Teija; Reponen, Tina; McKinstry, Craig A.; Cho, Seung H.; Grinshpun, Sergey A.; Nevalainen, Aino; Vepsalainen, Asko; Haugland, Richard A.; Lemasters, Grace; Vesper, Sephen J.

    2007-08-15

    Mold specific quantitative PCR (MSQPCR) was used to measure the concentrations of 36 mold species in dust and in indoor and in outdoor air samples that were taken simultaneously in 17 homes in Cincinnati with no-known water damage. The total spore concentrations in the indoor (I) and outdoor (O) air samples were statistically significantly different and the concentrations in the three sample types of many of the individual species were significantly different (p < 0.05 based on the Wilcoxon Signed Rank Test). The I/O ratios of the averages or geometric means of the individual species were generally less than 1; but these I/O ratios were quite variable ranging from 0.03 for A. sydowii to 1.2 for Acremonium strictum. There were no significant correlations for the 36 specific mold concentrations between the dust samples and the indoor or outdoor air samples (based on the Spearman’s Rho test). The indoor and outdoor air concentrations of 32 of the species were not correlated. Only Aspergillus penicillioides, C. cladosporioides types 1 and 2 and C. herbarum had sufficient data to estimate a correlation at rho > 0.5 with signicance (p < 0.05) In six of these homes, a previous dust sample had been collected and analyzed 2 years earlier. The ERMI© values for the dust samples taken in the same home two years apart were not significantly different (p=0.22) based on Wilcoxon Signed Rank Test.

  8. [Spatiotemporal distribution of negative air ion concentration in urban area and related affecting factors: a review].

    PubMed

    Huang, Xiang-Hua; Wang, Jian; Zeng, Hong-Da; Chen, Guang-Shui; Zhong, Xian-Fang

    2013-06-01

    Negative air ion (NAI) concentration is an important indicator comprehensively reflecting air quality, and has significance to human beings living environment. This paper summarized the spatiotemporal distribution features of urban NAI concentration, and discussed the causes of these features based on the characteristics of the environmental factors in urban area and their effects on the physical and chemical processes of NAI. The temporal distribution of NAI concentration is mainly controlled by the periodic variation of solar radiation, while the spatial distribution of NAI concentration along the urban-rural gradient is mainly affected by the urban aerosol distribution, underlying surface characters, and urban heat island effect. The high NAI concentration in urban green area is related to the vegetation life activities and soil radiation, while the higher NAI concentration near the water environment is attributed to the water molecules that participate in the generation of NAI through a variety of ways. The other environmental factors can also affect the generation, life span, component, translocation, and distribution of NAI to some extent. To increase the urban green space and atmospheric humidity and to maintain the soil natural attributes of underlying surface could be the effective ways to increase the urban NAI concentration and improve the urban air quality.

  9. Radon daughters' concentration in air and exposure of joggers at the university campus of Bangalore, India.

    PubMed

    Ashok, G V; Nagaiah, N; Shiva Prasad, N G

    2008-09-01

    The concentration of radon daughters in outdoor air was measured continuously from January 2006 to December 2006 near the Department of Physics, Bangalore University campus, Bangalore. The concentration was measured by collecting air samples at a height of 1 m above the ground level on a glass micro fibre filter paper with a known air flow rate. The results show that the radon progeny concentration exhibits distinct seasonal and diurnal variations that are predominantly caused by changes in the temperature gradient at the soil-atmosphere interface. The concentration was found to be high from 20.00 to 8.00 hrs, when the turbulence mixing was minimum and low during the rest of the time. In terms of the monthly concentration, January was found to be the highest with September/August being the lowest. The diurnal variations in the concentrations of radon progeny were found to exhibit positive correlation with the relative humidity and anti-correlation with the atmospheric temperature. From the measured concentration, an attempt was made to establish the annual effective dose to the general public of the region and was found to be 0.085 mSv/a. In addition, an attempt was also made for the first time to study the variation of inhalation dose with respect to the physical activity levels. Results show that in the light of both the effect of chemical pollutants and radiation dose due to inhalation of radon daughters, evening jogging is advisable.

  10. Rapid air titration method for determining SO/sub 2/ concentration in inhalation chambers

    SciTech Connect

    Snyder, E.A.; Palmes, E.D.

    1985-06-01

    A rapid air titration method for determining SO/sub 2/ concentration in inhalation chambers has been validated using the pararosaniline-formaldehyde (PRA) method of West and Gaeke. This air-titration (iodate) method is an adaptation of iodometric methods using a starch indicator. Potassium iodate and an excess of potassium iodide are used in the reaction. Sampling is completed in ten minutes or less and concentration is calculated by use of a simple formula. Linear equations were derived over the range of concentrations from 0.5 to 100 ppm SO/sub 2/ for uncorrected iodate bubbler results, data corrected for tandem bubbler concentrations and data corrected for mean iodate bubbler efficiency. Linear correlation with the PRA method over this range was 0.999 for all three sets of data.

  11. A Comparison of Statistical Techniques for Combining Modeled and Observed Concentrations to Create High-Resolution Ozone Air Quality Surfaces

    EPA Science Inventory

    Air quality surfaces representing pollutant concentrations across space and time are needed for many applications, including tracking trends and relating air quality to human and ecosystem health. The spatial and temporal characteristics of these surfaces may reveal new informat...

  12. [Interceptive treatment with the DAC appliance: structural analysis].

    PubMed

    Gebeile-Chauty, Sarah; Archer, Jean-Antoine; Lautrou, Alain; Aknin, Jean-Jacques

    2007-12-01

    The aim of this retrospective short and middle term study was to evaluate dental and skeletal effects during early class II treatment. Thirty subjects were treated with DAC appliance, 32 children were not treated. Data were collected at the start of the study (t(1)), after the active treatment (t(1')) and 28 months after t(1) (t(2)). L.D.V. and Tweed cephalometric analyses were applied on the lateral roentgenograms of the three groups. Differences for all the variables from t(1) to t(1') and t(2) were calculated and compared by t-test. Results suggested that DAC appliance was able to achieve twice more mandibular growth in the treated group than in the non treated group. Anterior total skeletal and matricial rotations were similar to control group. Early DAC appliance achieved overjet correction thanks to major skeletal participation (89%) and little dental participation (11%). During following-up stage, overjet relapsed partially as shown in other articles with other appliances. As a conclusion, DAC appliance may be an orthopedic appliance indicated to achieve correction in class II skeletal pattern without maxillary prognathism and with mandibular retrognathism.

  13. Monitor of the concentration of particles of dense radioactive materials in a stream of air

    DOEpatents

    Yule, Thomas J.

    1979-01-01

    A monitor of the concentration of particles of radioactive materials such as plutonium oxide in diameters as small as 1/2 micron includes in combination a first stage comprising a plurality of virtual impactors, a second stage comprising a further plurality of virtual impactors, a collector for concentrating particulate material, a radiation detector disposed near the collector to respond to radiation from collected material and means for moving a stream of air, possibly containing particulate contaminants, through the apparatus.

  14. Application of hybrid coagulation microfiltration with air backflushing to direct sewage concentration for organic matter recovery.

    PubMed

    Jin, Zhengyu; Gong, Hui; Wang, Kaijun

    2015-01-01

    The idea of sewage concentration is gradually being accepted as a promising and sustainable way of wastewater resource recovery. In this study, Hybrid coagulation microfiltration (HCM) with air backflushing (AB) was investigated to effectively concentrate organic matter. Compared to direct sewage microfiltration, the addition of coagulation process improved the filtration performance with less fouling trends and better concentration efficiency. The use of AB exhibited even better performance within the same 7-h preliminary concentration period by reducing to one tenth of the resistance and collecting around four times as much organic matter into the product concentrate as in direct sewage microfiltration. During 93-h lab-scale continuous concentration by HCM with AB, a product concentrate with the COD concentration over 15,000 mg/L was achieved and around 70% of total influent organic matter could be recovered. Compared to Direct Membrane Filtration (DMF) with Chemically Enhanced Backwash (CEB), HCM with AB achieved better concentration efficiency with higher concentration extent and concentration velocity along with less organic matter mineralization and the more concentrated product despite with lower organic matter retention. HCM with AB could be a promising effective sewage organic matter concentration for resource recovery under optimization.

  15. S3DACS - SPACE SIMULATOR SYSTEM DATA ACQUISITION AND CONTROL

    NASA Technical Reports Server (NTRS)

    De, Freitas Bart F.

    1994-01-01

    The S3 Data Acquisition and Control System, S3DACS, was developed for the Environmental Test Laboratory and Space Simulator at NASA's Jet Propulsion Laboratory. The program is used for monitoring, controlling, and recording information acquired during tests and presenting this information in various formats for easy access by a large number of users. All testing is initiated by a setup procedure that defines what will be tested, limits to be checked, formulas to use, etc. Test results (e.g. temperature, resistance) are then automatically stored in a database for real time display and for future reference. Measurements obtained may be used in various computations defined for the test and selectively presented in tabular, graphical, or electronic representation. Reports may show current or historical events. The S3DACS network software is written in FoxPro/LAN 1.02 and 80386 Assembler for IBM PC and compatibles running MS-DOS 3.31 or higher. Machine requirements include: an 80386 33MHz machine with 10Mb RAM set up as a file server; an 80386 33MHz machine with 4Mb RAM connected to a FLUKE 2240B or 2280 data acquisition device; and an 80386 20MHz machine with 5Mb RAM used as a workstation. Also needed is a National Instruments General Purpose Interface Bus-compatible (GP-IB) Board to enable S3DACS to communicate with IEEE-488 control instruments. Software requirements include: Novell Netware 386 for network management; FoxPro/LAN 1.02 for database management; QEMM 386 version 5.0 for memory management; and DGE version 4, Saywhat, Viewlib, and DBSHOW for graphics and screen displays. The previous list of hardware is the minimum configuration which will allow installation of S3DACS. The addition of workstations and data acquisition devices can occur transparently. S3DACS is distributed on one 5.25 inch 1.2Mb MS-DOS format diskette. The extensive documentation includes a Quick Reference Guide, a Software User's Manual, a Computer Systems Operator's Manual, and a Software

  16. Performance of the Proposed New Federal Reference Methods for Measuring Ozone Concentrations in Ambient Air

    EPA Science Inventory

    The current Federal Reference Method (FRM) for measuring concentrations of ozone in ambient air, described in EPA regulations at 40 CFR Part 50, Appendix D, is based on the dry, gas-phase, chemiluminescence reaction between ethylene (C2H4) and any ozone (O

  17. Effect of geocoding errors on traffic-related air pollutant exposure and concentration estimates

    EPA Science Inventory

    Exposure to traffic-related air pollutants is highest very near roads, and thus exposure estimates are sensitive to positional errors. This study evaluates positional and PM2.5 concentration errors that result from the use of automated geocoding methods and from linearized approx...

  18. Evaluation and Comparison of Chemiluminescence and UV Photometric Methods for Measuring Ozone Concentrations in Ambient Air

    EPA Science Inventory

    The current Federal Reference Method (FRM) for measuring concentrations of ozone in ambient air is based on the dry, gas-phase, chemiluminescence reaction between ethylene (C2H4) and any ozone (O3) that may be p...

  19. Modeling and Impacts of Traffic Emissions on Air Toxics Concentrations near Roadways

    EPA Science Inventory

    The dispersion formulation incorporated in the U.S. Environmental Protection Agency’s AERMOD regulatory dispersion model is used to estimate the contribution of traffic-generated emissions of select VOCs – benzene, 1,3-butadiene, toluene – to ambient air concentrations at downwin...

  20. Ozone concentrations and damage for realistic future European climate and air quality scenarios

    NASA Astrophysics Data System (ADS)

    Hendriks, Carlijn; Forsell, Nicklas; Kiesewetter, Gregor; Schaap, Martijn; Schöpp, Wolfgang

    2016-11-01

    Ground level ozone poses a significant threat to human health from air pollution in the European Union. While anthropogenic emissions of precursor substances (NOx, NMVOC, CH4) are regulated by EU air quality legislation and will decrease further in the future, the emissions of biogenic NMVOC (mainly isoprene) may increase significantly in the coming decades if short-rotation coppice plantations are expanded strongly to meet the increased biofuel demand resulting from the EU decarbonisation targets. This study investigates the competing effects of anticipated trends in land use change, anthropogenic ozone precursor emissions and climate change on European ground level ozone concentrations and related health and environmental impacts until 2050. The work is based on a consistent set of energy consumption scenarios that underlie current EU climate and air quality policy proposals: a current legislation case, and an ambitious decarbonisation case. The Greenhouse Gas-Air Pollution Interactions and Synergies (GAINS) integrated assessment model was used to calculate air pollutant emissions for these scenarios, while land use change because of bioenergy demand was calculated by the Global Biosphere Model (GLOBIOM). These datasets were fed into the chemistry transport model LOTOS-EUROS to calculate the impact on ground level ozone concentrations. Health damage because of high ground level ozone concentrations is projected to decline significantly towards 2030 and 2050 under current climate conditions for both energy scenarios. Damage to plants is also expected to decrease but to a smaller extent. The projected change in anthropogenic ozone precursor emissions is found to have a larger impact on ozone damage than land use change. The increasing effect of a warming climate (+2-5 °C across Europe in summer) on ozone concentrations and associated health damage, however, might be higher than the reduction achieved by cutting back European ozone precursor emissions. Global

  1. Autism spectrum disorder prevalence and associations with air concentrations of lead, mercury, and arsenic.

    PubMed

    Dickerson, Aisha S; Rahbar, Mohammad H; Bakian, Amanda V; Bilder, Deborah A; Harrington, Rebecca A; Pettygrove, Sydney; Kirby, Russell S; Durkin, Maureen S; Han, Inkyu; Moyé, Lemuel A; Pearson, Deborah A; Wingate, Martha Slay; Zahorodny, Walter M

    2016-07-01

    Lead, mercury, and arsenic are neurotoxicants with known effects on neurodevelopment. Autism spectrum disorder (ASD) is a neurodevelopmental disorder apparent by early childhood. Using data on 4486 children with ASD residing in 2489 census tracts in five sites of the Centers for Disease Control and Prevention's Autism and Developmental Disabilities Monitoring (ADDM) Network, we used multi-level negative binomial models to investigate if ambient lead, mercury, and arsenic concentrations, as measured by the US Environmental Protection Agency National-Scale Air Toxics Assessment (EPA-NATA), were associated with ASD prevalence. In unadjusted analyses, ambient metal concentrations were negatively associated with ASD prevalence. After adjusting for confounding factors, tracts with air concentrations of lead in the highest quartile had significantly higher ASD prevalence than tracts with lead concentrations in the lowest quartile (prevalence ratio (PR) = 1.36; 95 '% CI: 1.18, 1.57). In addition, tracts with mercury concentrations above the 75th percentile (>1.7 ng/m(3)) and arsenic concentrations below the 75th percentile (≤0.13 ng/m(3)) had a significantly higher ASD prevalence (adjusted RR = 1.20; 95 % CI: 1.03, 1.40) compared to tracts with arsenic, lead, and mercury concentrations below the 75th percentile. Our results suggest a possible association between ambient lead concentrations and ASD prevalence and demonstrate that exposure to multiple metals may have synergistic effects on ASD prevalence.

  2. Total internal reflection-based planar waveguide solar concentrator with symmetric air prisms as couplers.

    PubMed

    Xie, Peng; Lin, Huichuan; Liu, Yong; Li, Baojun

    2014-10-20

    We present a waveguide coupling approach for planar waveguide solar concentrator. In this approach, total internal reflection (TIR)-based symmetric air prisms are used as couplers to increase the coupler reflectivity and to maximize the optical efficiency. The proposed concentrator consists of a line focusing cylindrical lens array over a planar waveguide. The TIR-based couplers are located at the focal line of each lens to couple the focused sunlight into the waveguide. The optical system was modeled and simulated with a commercial ray tracing software (Zemax). Results show that the system used with optimized TIR-based couplers can achieve 70% optical efficiency at 50 × geometrical concentration ratio, resulting in a flux concentration ratio of 35 without additional secondary concentrator. An acceptance angle of ± 7.5° is achieved in the x-z plane due to the use of cylindrical lens array as the primary concentrator.

  3. Oxidative Nitration of Styrenes for the Recycling of Low-Concentrated Nitrogen Dioxide in Air.

    PubMed

    Hofmann, Dagmar; de Salas, Cristina; Heinrich, Markus R

    2015-09-21

    The oxidative nitration of styrenes in ethyl acetate represents a metal-free, environmentally friendly, and sustainable technique to recover even low concentrations of NO2 in air. Favorable features are that the product mixture comprising nitroalcohols, nitroketones, and nitro nitrates simplifies at lower concentrations of NO2 . Experiments in a miniplant-type 10 L wet scrubber demonstrated that the recycling technique is well applicable on larger scales at which initial NO2 concentrations of >10 000 ppm were reliably reduced to less than 40 ppm.

  4. Ozone concentration in leaf intercellular air spaces is close to zero

    SciTech Connect

    Laisk, A.; Moldau, H. ); Kull, O. )

    1989-07-01

    Transpiration and ozone uptake rates were measured simultaneously in sunflower leaves at different stomatal openings and various ozone concentrations. Ozone uptake rates were proportional to the ozone concentration up to 1500 nanoliters per liter. The leaf gas phase diffusion resistance (stomatal plus boundary layer) to water vapor was calculated and converted to the resistance to ozone multiplying it by the theoretical ratio of diffusion coefficients for water vapor and ozone in air (1.67). The ozone concentration in intercellular air spaces calculated from the ozone uptake rate and diffusion resistance to ozone scattered around zero. The ozone concentration in intercellular air spaces was measured directly bu supplying ozone to the leaf from one side and measuring the equilibrium concentration above the other side, and it was found to be zero. The total leaf resistance to ozone was proportional to the gas phase resistance to water vapor with a coefficient of 1.68. It is concluded that ozone enters the leaf by diffusion through the stomata, and is rapidly decomposed in cell walls and plasmalemma.

  5. Forecasting 7BE concentrations in surface air using time series analysis

    NASA Astrophysics Data System (ADS)

    Bas, María del Carmen; Ortiz, Josefina; Ballesteros, Luisa; Martorell, Sebastián

    2017-04-01

    7Be is a cosmogenic radionuclide widely used as an atmospheric tracer, whose evaluation and forecasting can provide valuable information on changes in the atmospheric behavior. In this study, measurements of 7Be concentrations were made each month during the period 2007-2015 from samples of atmospheric aerosols filtered from the air. The aim was to propose a Seasonal Autoregressive Integrated Moving Average (SARIMA) model to develop an explanatory and predictive model of 7Be air concentrations. The Root Mean Square Error (RMSE) and the Adapted Mean Absolute Percentage Error (AMAPE) were selected to measure forecasting accuracy in identifying the best historical data time window to explain 7Be concentrations. A measure based on the variance of forecast errors was calculated to determine the impact of the model uncertainty on forecasts. We concluded that the SARIMA method is a powerful explanatory and predictive technique for explaining 7Be air concentrations in a longterm series of at least eight years of historical data to forecast 7Be concentration trends up to one year in advance.

  6. Ozone Concentration in Leaf Intercellular Air Spaces Is Close to Zero 1

    PubMed Central

    Laisk, Agu; Kull, Olevi; Moldau, Heino

    1989-01-01

    Transpiration and ozone uptake rates were measured simultaneously in sunflower leaves at different stomatal openings and various ozone concentrations. Ozone uptake rates were proportional to the ozone concentration up to 1500 nanoliters per liter. The leaf gas phase diffusion resistance (stomatal plus boundary layer) to water vapor was calculated and converted to the resistance to ozone multiplying it by the theoretical ratio of diffusion coefficients for water vapor and ozone in air (1.67). The ozone concentration in intercellular air spaces calculated from the ozone uptake rate and diffusion resistance to ozone scattered around zero. The ozone concentration in intercellular air spaces was measured directly by supplying ozone to the leaf from one side and measuring the equilibrium concentration above the other side, and it was found to be zero. The total leaf resistance to ozone was proportional to the gas phase resistance to water vapor with a coefficient of 1.68. It is concluded that ozone enters the leaf by diffusion through the stomata, and is rapidly decomposed in cell walls and plasmalemma. PMID:16666867

  7. Short-term concentration of CO2 in the ambient air of Nagpur city.

    PubMed

    Manuel, Jovita A; Gajghate, D G; Hasan, M Z; Singh, R N

    2002-07-01

    Carbon dioxide concentration is an index of total amount of combustion and natural ventilation in an urban environment and therefore required more careful attention for assessment of CO2 level in air environment. First time, an attempt was made to monitor CO2 levels in Ambient Air of Nagpur during August 2001-December 2001 at Industrial, Commercial and Residential sites. The largest amount of CO2 occurred at night due to darkness which depresses the photosynthesis to its lowest level. The lowest concentration of CO2 was showed in afternoon hours when photosynthesis is at its maximum. The average concentration of CO2 was found to be 361, 366 and 339 ppm at Industrial, Commercial and Industrial sites respectively. This generation of database of ambient CO2 will help to formulate the strategy for prevention of global warming phenomenon.

  8. Relevance of air conditioning for 222Radon concentration in shops of the Savona Province, Italy.

    PubMed

    Panatto, Donatella; Ferrari, Paola; Lai, Piero; Gallelli, Giovanni

    2006-02-15

    Radon (222Rn) concentration was evaluated in shops of the Savona Province, Italy, between summer 2002 and winter 2002-2003. The main characteristics of each shops were recorded through a questionnaire investigating the ventilation rate and factors related to 222Rn precursors in the soil and the construction materials. The main variables that were related to radon concentration were the following: age of the building, level of the shop above ground, season of the year, wind exposure, active windows, and type of heating system. Shops equipped with individual air heating/conditioning systems exhibited radon concentrations that were three times higher than those of shops heated by centralized furnaces. Our data indicate that the level of pollution in the shops was of medium level, with an expected low impact on the salespersons' health. Only in wintertime, the action level of 200 Bq m(-3) for the confined environment was reached in 10 shops equipped with individual air heating/conditioning systems.

  9. Fungal spore concentrations in two haematopoietic stem cell transplantation (HSCT) units containing distinct air control systems.

    PubMed

    Brun, C P; Miron, D; Silla, L M R; Pasqualotto, A C

    2013-04-01

    Invasive fungal diseases have emerged as important causes of morbidity and mortality in haematological patients. In this study air samples were collected in two haematopoietic stem cell transplantation (HSCT) units, in which distinct air-control systems were in place. In hospital 1 no high-efficiency particulate air (HEPA) filter was available whereas in hospital 2 HSCT rooms were equipped with HEPA filters, with positive air pressure in relation to the corridor. A total of 117 samples from rooms, toilets and corridors were obtained during December 2009 to January 2011, using a six-stage Andersen sampler. In both hospitals, the concentration of potentially pathogenic fungi in the air was reduced in patients' rooms compared to corridors (P < 0·0001). Despite the presence of a HEPA filter in hospital 2, rooms in both hospitals showed similar concentrations of potentially pathogenic fungi (P = 0·714). These findings may be explained by the implementation of additional protective measures in hospital 1, emphasizing the importance of such measures in protected environments.

  10. Concentrations and decay rates of ozone in indoor air in dependence on building and surface materials.

    PubMed

    Moriske, H J; Ebert, G; Konieczny, L; Menk, G; Schöndube, M

    1998-08-01

    The decay of ozone in indoor air was measured in a closed chamber after contact with different building materials and residential surfaces. The tested materials were: vinyl wall paper, woodchip paper, plywood, latex paint, fitted carpet, and plaster. In the summer of 1996, the entry of ozone from ambient air into indoor air during ventilation and the ozone decay in indoor air, after windows had been closed again, were studied. Measurements were done in a residential house on the outskirts of Berlin. The following results were gained: the chamber measurements showed a decay of ozone after contact with most of the materials put inside the chamber. Higher decay rates have been obtained for wall papers, plywood, fitted carpet and plaster. As described in the literature, ozone is able to react with olefines inside the materials and is able to form formaldehyde and other components. This formation of formaldehyde could also be confirmed in our investigations. Thus, in most cases, the formaldehyde concentrations were lower than the German guideline value of 0.1 ppm. The formation of formaldehyde could be prevented when a special wall paper that was coated with activated carbon was used. In the house, a complete ozone diffusion into indoor air took place during ventilation within 30 min. After closing the windows, the ozone concentrations decreased to the basic level before ventilation within 60-90 min.

  11. Low-CCN concentration air masses over the eastern North Atlantic: Seasonality, meteorology, and drivers

    NASA Astrophysics Data System (ADS)

    Wood, Robert; Stemmler, Jayson D.; Rémillard, Jasmine; Jefferson, Anne

    2017-01-01

    A 20 month cloud condensation nucleus concentration (NCCN) data set from Graciosa Island (39°N, 28°W) in the remote North Atlantic is used to characterize air masses with low cloud condensation nuclei (CCN) concentrations. Low-CCN events are defined as 6 h periods with mean NCCN<20 cm-3 (0.1% supersaturation). A total of 47 low-CCN events are identified. Surface, satellite, and reanalysis data are used to explore the meteorological and cloud context for low-CCN air masses. Low-CCN events occur in all seasons, but their frequency was 3 times higher in December-May than during June-November. Composites show that many of the low-CCN events had a common meteorological basis that involves southerly low-level flow and rather low wind speeds at Graciosa. Anomalously low pressure is situated to the west of Graciosa during these events, but back trajectories and lagged SLP composites indicate that low-CCN air masses often originate as cold air outbreaks to the north and west of Graciosa. Low-CCN events were associated with low cloud droplet concentrations (Nd) at Graciosa, but liquid water path (LWP) during low-CCN events was not systematically different from that at other times. Satellite Nd and LWP estimates from MODIS collocated with Lagrangian back trajectories show systematically lower Nd and higher LWP several days prior to arrival at Graciosa, consistent with the hypothesis that observed low-CCN air masses are often formed by coalescence scavenging in thick warm clouds, often in cold air outbreaks.

  12. Impact of traffic flows and wind directions on air pollution concentrations in Seoul, Korea

    NASA Astrophysics Data System (ADS)

    Kim, Youngkook; Guldmann, Jean-Michel

    2011-05-01

    Vehicle emissions are responsible for a substantial share of urban air pollution concentrations. Various integrated air quality modeling systems have been developed to analyze the consequences of air pollution caused by traffic flows. However, the quantitative relationship between vehicle-kilometers-traveled (VKT) and pollution concentrations while considering wind direction effects has rarely been explored in the context of land-use regression models (LUR). In this research, VKTs occurring within circular buffers around air pollution monitoring stations are simulated, using a traffic assignment model, and weighted by eight wind directions frequencies. The relationships between monitored pollution concentrations and weighted VKTs are estimated using regression analysis. In general, the wind direction weighted VKT variable increases the explanatory power of the models, particularly for nitrogen dioxide and carbon monoxide. The case of ozone is more complex, due to the effects of solar radiation, which appears to overwhelm the effects of wind direction in the afternoon hours. The statistical significance of the weighted VKT variable is high, which makes the models appropriate for impact analysis of traffic flow growth.

  13. Air concentrations of PBDEs on in-flight airplanes and assessment of flight crew inhalation exposure.

    PubMed

    Allen, Joseph G; Sumner, Ann Louise; Nishioka, Marcia G; Vallarino, Jose; Turner, Douglas J; Saltman, Hannah K; Spengler, John D

    2013-07-01

    To address the knowledge gaps regarding inhalation exposure of flight crew to polybrominated diphenyl ethers (PBDEs) on airplanes, we measured PBDE concentrations in air samples collected in the cabin air at cruising altitudes and used Bayesian Decision Analysis (BDA) to evaluate the likelihood of inhalation exposure to result in the average daily dose (ADD) of a member of the flight crew to exceed EPA Reference Doses (RfDs), accounting for all other aircraft and non-aircraft exposures. A total of 59 air samples were collected from different aircraft and analyzed for four PBDE congeners-BDE 47, 99, 100 and 209 (a subset were also analyzed for BDE 183). For congeners with a published RfD, high estimates of ADD were calculated for all non-aircraft exposure pathways and non-inhalation exposure onboard aircraft; inhalation exposure limits were then derived based on the difference between the RfD and ADDs for all other exposure pathways. The 95th percentile measured concentrations of PBDEs in aircraft air were <1% of the derived inhalation exposure limits. Likelihood probabilities of 95th percentile exposure concentrations >1% of the defined exposure limit were zero for all congeners with published RfDs.

  14. Biomimetic air sampling for detection of low concentrations of molecules and bioagents : LDRD 52744 final report.

    SciTech Connect

    Hughes, Robert Clark

    2003-12-01

    Present methods of air sampling for low concentrations of chemicals like explosives and bioagents involve noisy and power hungry collectors with mechanical parts for moving large volumes of air. However there are biological systems that are capable of detecting very low concentrations of molecules with no mechanical moving parts. An example is the silkworm moth antenna which is a highly branched structure where each of 100 branches contains about 200 sensory 'hairs' which have dimensions of 2 microns wide by 100 microns long. The hairs contain about 3000 pores which is where the gas phase molecules enter the aqueous (lymph) phase for detection. Simulations of diffusion of molecules indicate that this 'forest' of hairs is 'designed' to maximize the extraction of the vapor phase molecules. Since typical molecules lose about 4 decades in diffusion constant upon entering the liquid phase, it is important to allow air diffusion to bring the molecule as close to the 'sensor' as possible. The moth acts on concentrations as low as 1000 molecules per cubic cm. (one part in 1e16). A 3-D collection system of these dimensions could be fabricated by micromachining techniques available at Sandia. This LDRD addresses the issues involved with extracting molecules from air onto micromachined structures and then delivering those molecules to microsensors for detection.

  15. The Impact of Future Emissions Changes on Air Pollution Concentrations and Related Human Health Effects

    NASA Astrophysics Data System (ADS)

    Mikolajczyk, U.; Suppan, P.; Williams, M.

    2015-12-01

    Quantification of potential health benefits of reductions in air pollution on the local scale is becoming increasingly important. The aim of this study is to conduct health impact assessment (HIA) by utilizing regionally and spatially specific data in order to assess the influence of future emission scenarios on human health. In the first stage of this investigation, a modeling study was carried out using the Weather Research and Forecasting (WRF) model coupled with Chemistry to estimate ambient concentrations of air pollutants for the baseline year 2009, and for the future emission scenarios in southern Germany. Anthropogenic emissions for the baseline year 2009 are derived from the emission inventory provided by the Netherlands Organization of Applied Scientific Research (TNO) (Denier van der Gon et al., 2010). For Germany, the TNO emissions were replaced by gridded emission data with a high spatial resolution of 1/64 x 1/64 degrees. Future air quality simulations are carried out under different emission scenarios, which reflect possible energy and climate measures in year 2030. The model set-up included a nesting approach, where three domains with horizontal resolution of 18 km, 6 km and 2 km were defined. The simulation results for the baseline year 2009 are used to quantify present-day health burdens. Concentration-response functions (CRFs) for PM2.5 and NO2 from the WHO Health risks of air Pollution in Europe (HRAPIE) project were applied to population-weighted mean concentrations to estimate relative risks and hence to determine numbers of attributable deaths and associated life-years lost. In the next step, future health impacts of projected concentrations were calculated taking into account different emissions scenarios. The health benefits that we assume with air pollution reductions can be used to provide options for future policy decisions to protect public health.

  16. Air toxics concentrations, source identification, and health risks: An air pollution hot spot in southwest Memphis, TN

    NASA Astrophysics Data System (ADS)

    Jia, Chunrong; Foran, Jeffery

    2013-12-01

    Southwest Memphis is a residential region surrounded by fossil fuel burning, steel, refining, and food processing industries, and considerable mobile sources whose emissions may pose adverse health risks to local residents. This study characterizes cancer and non-cancer risks resulting from exposure to ambient air toxics in southwest Memphis. Air toxics samples were collected at a central location every 6 days from June 5, 2008 to January 8, 2010. Volatile organic compounds (VOCs) were collected in evacuated stainless-steel canisters and aldehydes by DNPH cartridges, and samples were analyzed for 73 target compounds. A total of 60 compounds were detected and 39 were found in over 86% of the samples. Mean concentrations of many compounds were higher than those measured in many industrial communities throughout the U.S. The cumulative cancer risk associated with exposure to 13 carcinogens found in southwest Memphis air was 2.3 × 10-4, four times higher than the national average of 5.0 × 10-5. Three risk drivers were identified: benzene, formaldehyde, and acrylonitrile, which contributed 43%, 19%, and 14% to the cumulative risk, respectively. This is the first field study to confirm acrylonitrile as a potential risk driver. Mobile, secondary, industrial, and background sources contributed 57%, 24%, 14%, and 5% of the risk, respectively. The results of this study indicate that southwest Memphis, a region of significant income, racial, and social disparities, is also a region under significant environmental stress compared with surrounding areas and communities.

  17. Transport of semivolatile organic compounds to the Tibetan Plateau: Monthly resolved air concentrations at Nam Co

    NASA Astrophysics Data System (ADS)

    Xiao, Hang; Kang, Shichang; Zhang, Qianggong; Han, Wenwu; Loewen, Mark; Wong, Fiona; Hung, Hayley; Lei, Ying D.; Wania, Frank

    2010-08-01

    A flow-through sampler was deployed to record the seasonal variability of the atmospheric concentrations of semivolatile organic compounds (SOCs) at a remote research station located close to Nam Co Lake on the Tibetan plateau. Between October 2006 and February 2008, fifteen consecutive one month-long samples, with air volumes ranging from 4,500 to 16,000 m3, were taken and analyzed for polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs) and organochlorine pesticides (OCPs). Separate analysis of three polyurethane plugs in series in combination with frontal chromatographic theory allows for the correction of the break-through observed for the most volatile SOCs. The concentrations of Σ56PCB in air range from 0.10 to 2.6 pg·m-3 and are among the lowest values ever reported. Levels of OCPs at Nam Co are generally also very low, particularly during wintertime. The concentrations of hexachlorocyclohexanes (HCHs), endosulfans, and various dichlorodiphenyltrichloroethane (DDT) related substances display a distinct seasonal variability consistent with the monsoon. Back-trajectory analysis reveals that higher OCP levels during summer correlate with air mass origin south of the Himalayas. A high α/γ-HCH ratio and a non-racemic composition of α-HCH during July/August suggest that evaporation from Nam Co Lake contributes to the relatively high concentrations of α-HCH (averaging ca. 91 pg·m-3) recorded in the summertime atmosphere.

  18. Assessment of regional air quality by a concentration-dependent Pollution Permeation Index

    NASA Astrophysics Data System (ADS)

    Liang, Chun-Sheng; Liu, Huan; He, Ke-Bin; Ma, Yong-Liang

    2016-10-01

    Although air quality monitoring networks have been greatly improved, interpreting their expanding data in both simple and efficient ways remains challenging. Therefore, needed are new analytical methods. We developed such a method based on the comparison of pollutant concentrations between target and circum areas (circum comparison for short), and tested its applications by assessing the air pollution in Jing-Jin-Ji, Yangtze River Delta, Pearl River Delta and Cheng-Yu, China during 2015. We found the circum comparison can instantly judge whether a city is a pollution permeation donor or a pollution permeation receptor by a Pollution Permeation Index (PPI). Furthermore, a PPI-related estimated concentration (original concentration plus halved average concentration difference) can be used to identify some overestimations and underestimations. Besides, it can help explain pollution process (e.g., Beijing’s PM2.5 maybe largely promoted by non-local SO2) though not aiming at it. Moreover, it is applicable to any region, easy-to-handle, and able to boost more new analytical methods. These advantages, despite its disadvantages in considering the whole process jointly influenced by complex physical and chemical factors, demonstrate that the PPI based circum comparison can be efficiently used in assessing air pollution by yielding instructive results, without the absolute need for complex operations.

  19. Assessment of regional air quality by a concentration-dependent Pollution Permeation Index

    PubMed Central

    Liang, Chun-Sheng; Liu, Huan; He, Ke-Bin; Ma, Yong-Liang

    2016-01-01

    Although air quality monitoring networks have been greatly improved, interpreting their expanding data in both simple and efficient ways remains challenging. Therefore, needed are new analytical methods. We developed such a method based on the comparison of pollutant concentrations between target and circum areas (circum comparison for short), and tested its applications by assessing the air pollution in Jing-Jin-Ji, Yangtze River Delta, Pearl River Delta and Cheng-Yu, China during 2015. We found the circum comparison can instantly judge whether a city is a pollution permeation donor or a pollution permeation receptor by a Pollution Permeation Index (PPI). Furthermore, a PPI-related estimated concentration (original concentration plus halved average concentration difference) can be used to identify some overestimations and underestimations. Besides, it can help explain pollution process (e.g., Beijing’s PM2.5 maybe largely promoted by non-local SO2) though not aiming at it. Moreover, it is applicable to any region, easy-to-handle, and able to boost more new analytical methods. These advantages, despite its disadvantages in considering the whole process jointly influenced by complex physical and chemical factors, demonstrate that the PPI based circum comparison can be efficiently used in assessing air pollution by yielding instructive results, without the absolute need for complex operations. PMID:27731344

  20. Outdoor air PCB concentrations in three communities along the Upper Hudson River, New York.

    PubMed

    Palmer, Patrick M; Belanger, Erin E; Wilson, Lloyd R; Hwang, Syni-An A; Narang, Rajinder S; Gomez, Marta I; Cayo, Michael R; Durocher, Lorie A; Fitzgerald, Edward F

    2008-04-01

    Outdoor air polychlorinated biphenyl (PCB) concentrations were measured in upstate New York as part of a nonoccupational exposure investigation. The adjacent study communities of Hudson Falls and Fort Edward contain numerous sites of current and former PCB contamination, including two capacitor-manufacturing facilities. Outdoor air PCB concentrations in the study municipalities were significantly higher than in the comparison municipality of Glens Falls. Total PCB concentrations in the study area ranged from 0.102 to 4.011 ng/m(3) (median: 0.711 ng/m(3)). For the comparison area, concentrations ranged from 0.080 to 2.366 ng/m(3) (median: 0.431 ng/m(3)). Although our sampling was not designed to identify point sources, the presence of PCB-contaminated sites in the study area likely contributed to this observed difference in concentration. While elevated relative to the comparison area, total PCB concentrations in the study area are lower than those in other communities with known PCB-contaminated sites, and similar to levels reported in other locations from the northeastern United States.

  1. MODELING AIR TOXICS AND PM 2.5 CONCENTRATION FIELDS AS A MEANS FOR FACILITATING HUMAN EXPOSURE ASSESSMENTS

    EPA Science Inventory

    The capability of the US EPA Models-3/Community Multiscale Air Quality (CMAQ) modeling system is extended to provide gridded ambient air quality concentration fields at fine scales. These fields will drive human exposure to air toxics and fine particulate matter (PM2.5) models...

  2. Contribution of ship emissions to the concentration and deposition of air pollutants in Europe

    NASA Astrophysics Data System (ADS)

    Aksoyoglu, S.; Prévôt, A. S. H.; Baltensperger, U.

    2015-11-01

    Emissions from the marine transport sector are one of the least regulated anthropogenic emission sources and contribute significantly to air pollution. Although strict limits were introduced recently for the maximum sulfur content in marine fuels in the SECAs (sulfur emission control areas) and in the EU ports, sulfur emissions outside the SECAs and emissions of other components in all European maritime areas have continued to increase in the last two decades. We have used the air quality model CAMx with and without ship emissions for the year 2006 to determine the effects of international shipping on the annual as well as seasonal concentrations of ozone, primary and secondary components of PM2.5 and the dry and wet deposition of nitrogen and sulfur compounds in Europe. Our results suggest that emissions from international shipping affect the air quality in northern and southern Europe differently and their contributions to the air concentrations vary seasonally. The largest changes in pollutant concentrations due to ship emissions were predicted for summer. Increased concentrations of the primary particle mass were found only along the shipping routes whereas concentrations of the secondary pollutants were affected over a larger area. Concentrations of particulate sulfate increased due to ship emissions in the Mediterranean (up to 60 %), in the English Channel and the North Sea (30-35 %) while increases in particulate nitrate levels were found especially in the north, around the Benelux area (20 %) where there were high NH3 land-based emissions. Our model results showed that not only the atmospheric concentrations of pollutants are affected by ship emissions, but also depositions of nitrogen and sulfur compounds increase significantly along the shipping routes. NOx emissions from the ships especially in the English Channel and the North Sea, cause a decrease in the dry deposition of reduced nitrogen at source regions by moving it from the gas-phase to the

  3. Effect of outside air ventilation rate on volatile organic compound concentrations in a call center

    NASA Astrophysics Data System (ADS)

    Hodgson, A. T.; Faulkner, D.; Sullivan, D. P.; DiBartolomeo, D. L.; Russell, M. L.; Fisk, W. J.

    A study of the relationship between outside air ventilation rate and concentrations of volatile organic compounds (VOCs) generated indoors was conducted in a call center office building. The building, with two floors and a total floor area of 4600 m 2, is located in the San Francisco Bay Area, CA. Ventilation rates were manipulated with the building's four air handling units (AHUs). VOC and CO 2 concentrations in the AHU returns were measured on 7 days during a 13-week period. VOC emission factors were determined for individual zones on days when they were operating at near steady-state conditions. The emission factor data were subjected to principal component (PC) analysis to identify groups of co-varying compounds. Potential sources of the PC vectors were ascribed based on information from the literature. The per occupant CO 2 generation rates were 0.0068-0.0092 l s -1. The per occupant isoprene generation rates of 0.2-0.3 mg h -1 were consistent with the value predicted by mass balance from breath concentration and exhalation rate. The relationships between indoor minus outdoor VOC concentrations and ventilation rate were qualitatively examined for eight VOCs. Of these, acetaldehyde and hexanal, which likely were associated with material sources, and decamethylcyclopentasiloxane, associated with personal care products, exhibited general trends of higher concentrations at lower ventilation rates. For other compounds, a clear inverse relationship between VOC concentrations and ventilation was not observed. The net concentration of 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate isomers, examples of low-volatility compounds, changed very little with ventilation likely due to sorption and re-emission effects. These results illustrate that the efficacy of ventilation for controlling VOC concentrations can vary considerably depending upon the operation of the building, the pollutant sources and the physical and chemical processes affecting the pollutants. Thus, source

  4. Concentrations in ambient air and emissions of cyclic volatile methylsiloxanes in Zurich, Switzerland.

    PubMed

    Buser, Andreas M; Kierkegaard, Amelie; Bogdal, Christian; MacLeod, Matthew; Scheringer, Martin; Hungerbühler, Konrad

    2013-07-02

    Tens of thousands of tonnes of cyclic volatile methylsiloxanes (cVMS) are used each year globally, which leads to high and continuous cVMS emissions to air. However, field measurements of cVMS in air and empirical information about emission rates to air are still limited. Here we present measurements of decamethylcyclopentasiloxane (D5) and dodecamethylcyclohexasiloxane (D6) in air for Zurich, Switzerland. The measurements were performed in January and February 2011 over a period of eight days and at two sites (city center and background) with a temporal resolution of 6-12 h. Concentrations of D5 and D6 are higher in the center of Zurich and range from 100 to 650 ng m(-3) and from 10 to 79 ng m(-3), respectively. These values are among the highest levels of D5 and D6 reported in the literature. In a second step, we used a multimedia environmental fate model parametrized for the region of Zurich to interpret the levels and time trends in the cVMS concentrations and to back-calculate the emission rates of D5 and D6 from the city of Zurich. The average emission rates obtained for D5 and D6 are 120 kg d(-1) and 14 kg d(-1), respectively, which corresponds to per-capita emissions of 310 mg capita(-1) d(-1) for D5 and 36 mg capita(-1) d(-1) for D6.

  5. Comparing air dispersion model predictions with measured concentrations of VOCs in urban communities.

    PubMed

    Pratt, Gregory C; Wu, Chun Yi; Bock, Don; Adgate, John L; Ramachandran, Gurumurthy; Stock, Thomas H; Morandi, Maria; Sexton, Ken

    2004-04-01

    Air concentrations of nine volatile organic compounds were measured over 48-h periods at 23 locations in three communities in the Minneapolis-St. Paul metropolitan area. Concentrations at the same times and locations were modeled using a standard regulatory air dispersion model (ISCST3). The goal of the study was to evaluate model performance by comparing predictions with measurements using linear regression and estimates of bias. The modeling, done with mobile and area source emissions resolved to the census tract level and characterized as model area sources, represents an improvement over large-scale airtoxics modeling analyses done to date. Despite the resolved spatial scale, the model did not fully capture the spatial resolution in concentrations in an area with a sharp gradient in emissions. In a census tract with a major highway at one end of the tract (i.e., uneven distribution of emissions within the tract), model predictions atthe opposite end of the tract overestimated measured concentrations. This shortcoming was seen for pollutants emitted mainly by mobile sources (benzene, ethylbenzene, toluene, and xylenes). We suggest that major highways would be better characterized as line sources. The model also failed to fully capture the temporal variability in concentrations, which was expected since the emissions inventory comprised annual average values. Based on our evaluation metrics, model performance was best for pollutants emitted mainly from mobile sources and poorest for pollutants emitted mainlyfrom area sources. Important sources of error appeared to be the source characterization (especially location) and emissions quantification. We expect that enhancements in the emissions inventory would give the greatest improvement in results. As anticipated for a Gaussian plume model, performance was dramatically better when compared to measurements that were not matched in space or time. Despite the limitations of our analysis, we found thatthe regulatory

  6. [A novel anticancer drug delivery system -DAC-70/CDDP].

    PubMed

    Sugitachi, Akio; Otsuka, Koki; Fujisawa, Kentaro; Itabashi, Tetsuya; Akiyama, Yuji; Sasaki, Akira; Ikeda, Kenichiro; Yoshida, Yasuo; Takamori, Yoshimori; Kurozumi, Seiji; Mori, Takatoshi; Wakabayashi, Go

    2007-11-01

    We devised a muco-adhesive anticancer drug delivery system using 70% deacetylated chitin (DAC-70) and cisplatin (CDDP) and 5-fluorouracil (5-FU). The adhesive force between the system and human colonic mucosa was measured ex vivo, and a release profile of each drug was examined in vitro. Each system demonstrated a stronger muco-adhesive force at 37 degrees C than that of 25 degrees C. The CDDP-loaded system showed a sustained release of the drug while the 5-FU-loaded system exhibited an initial bursting of the agent. We presume that the release profile of CDDP and 5-FU is closely related to both degradability of the chitin and interactions between the chitin and each drug. The DAC-70/CDDP system would be clinically promising in loco-regional cancer chemotherapy.

  7. Particulate matter concentrations in residences: an intervention study evaluating stand-alone filters and air conditioners

    PubMed Central

    Batterman, S.; Du, L.; Mentz, G.; Mukherjee, B.; Parker, E.; Godwin, C.; Chin, J.-Y.; O'Toole, A.; Robins, T.; Rowe, Z.; Lewis, T.

    2014-01-01

    This study, a randomized controlled trial, evaluated the effectiveness of free-standing air filters and window air conditioners (ACs) in 126 low-income households of children with asthma. Households were randomized into a control group, a group receiving a free-standing HEPA filter placed in the child's sleeping area, and a group receiving the filter and a window-mounted AC. Indoor air quality (IAQ) was monitored for week-long periods over three to four seasons. High concentrations of particulate matter (PM) and carbon dioxide were frequently seen. When IAQ was monitored, filters reduced PM levels in the child's bedroom by an average of 50%. Filter use varied greatly among households and declined over time, for example, during weeks when pollutants were monitored, filter use was initially high, averaging 84 ± 27%, but dropped to 63 ± 33% in subsequent seasons. In months when households were not visited, use averaged only 34 ± 30%. Filter effectiveness did not vary in homes with central or room ACs. The study shows that measurements over multiple seasons are needed to characterize air quality and filter performance. The effectiveness of interventions using free-standing air filters depends on occupant behavior, and strategies to ensure filter use should be an integral part of interventions. PMID:22145709

  8. Natural ³⁷Ar concentrations in soil air: implications for monitoring underground nuclear explosions.

    PubMed

    Riedmann, Robin A; Purtschert, Roland

    2011-10-15

    For on-site inspections (OSI) under the Comprehensive Nuclear-Test-Ban Treaty (CTBT) measurement of the noble gas ³⁷Ar is considered an important technique. ³⁷Ar is produced underground by neutron activation of Calcium by the reaction ⁴⁰Ca(n,α)³⁷Ar. The naturally occurring equilibrium ³⁷Ar concentration balance in soil air is a function of an exponentially decreasing production rate from cosmic ray neutrons with increasing soil depth, diffusive transport in the soil air, and radioactive decay (T(1/2): 35 days). In this paper for the first time, measurements of natural ³⁷Ar activities in soil air are presented. The highest activities of ~100 mBq m⁻³ air are 2 orders of magnitude larger than in the atmosphere and are found in 1.5-2.5 m depth. At depths > 8 m ³⁷Ar activities are < 20 mBq m⁻³ air. After identifying the main ³⁷Ar production and gas transport factors the expected global activity range distribution of ³⁷Ar in shallow subsoil (0.7 m below the surface) was estimated. In high altitude soils, with large amounts of Calcium and with low gas permeability, ³⁷Ar activities may reach values up to 1 Bq m⁻³.

  9. Determination of radionuclide concentrations in ground level air using the ASS-500 high volume sampler

    SciTech Connect

    Frenzel, E.; Arnold, D.; Wershofen, H.

    1996-06-01

    A method for determination of radionuclide concentrations in air aerosol samples collected by the high volume aerosol sampler ASS-500 was elaborated. The aerosol sampling station ASS-500 is a Stand alone, all-weather proofed instrument. It is designed for representative sampling of airborne radionuclides from ground level air at a height of about 1.5 m above ground level. The ASS-500 station enables continuous air monitoring both normal and emergency Situations. The collection of aerosols on the Petrianov FPP-15-1.5 type filter out of an air volume of about 100,000 m{sup 3} (sampling period 1 wk) or of about 250,000 m{sup 3} (sampling period 3 wk) admits accurate spectrometric low level measurements of natural and artificial radionuclides. The achieved detection limit is 0.5 {mu}Bq m{sup -3} and 0.2 {mu}Bq m{sup -3} for {sup 137}Cs, respectively. A new developed air flow Meter system allows to enhance the collected air volume to about 150,000 m{sup 3} per week and lowers the detection limit to <0.4 {mu}Bq m{sup -3} for {sup 137}Cs for weekly collected aerosol samples. In Poland the CLOR uses 9 Stations ASS-500 at different sites as atmospheric radioactivity control system. On the basis of spectrometric measurements of natural and artificial radionuclides in the collected aerosol samples at the different sites, CLOR establishes a weekly report about the radiological situation at Poland for responsible authorities. The very low achievable detection limit of the Station ASS-500 due 10 the high air flow fate and the long possible sampling period were the key argument for other government radiation protection authorities in Europe to introduce the Station ASS-500 into their low level radionuclide atmospheric monitoring programs (Austria, Belarus, France, Germany, Iceland, Spain, Switzerland, Ukraine).

  10. Amine nitrosation via NO reduction of the polyamine copper(II) complex Cu(DAC)2+.

    PubMed

    Khin, Chosu; Lim, Mark D; Tsuge, Kiyoshi; Iretskii, Alexei; Wu, Guang; Ford, Peter C

    2007-10-29

    The reaction of the fluorescent macrocyclic ligand 1,8-bis(anthracen-9-ylmethyl)-1,4,8,11-tetraazacyclotetradecane with copper(II) salts leads to formation of the Cu(DAC)2+ cation (I), which is not luminescent. However, when aqueous methanol solutions of I are allowed to react with NO, fluorescence again develops, owing to the formation of the strongly luminescent N-nitrosated ligand DAC-NO (II), which is released from the copper center. This reaction is relatively slow in neutral media, and kinetics studies show it to be first order in the concentrations of NO and base. In these contexts, it is proposed that the amine nitrosation occurs via NO attack at a coordinated amine that has been deprotonated and that this step occurs with concomitant reduction of the Cu(II) to Cu(I). DFT computations at the BP/LACVP* level support these mechanistic arguments. It is further proposed that such nitrosation of electron-rich ligands coordinated to redox-active metal centers is a mechanistic pathway that may find greater generality in the biochemical formation of nitrosothiols and nitrosoamines.

  11. Groundwater level and nitrate concentration trends on Mountain Home Air Force Base, southwestern Idaho

    USGS Publications Warehouse

    Williams, Marshall L.

    2014-01-01

    Mountain Home Air Force Base in southwestern Idaho draws most of its drinking water from the regional aquifer. The base is located within the State of Idaho's Mountain Home Groundwater Management Area and is adjacent to the State's Cinder Cone Butte Critical Groundwater Area. Both areas were established by the Idaho Department of Water Resources in the early 1980s because of declining water levels in the regional aquifer. The base also is listed by the Idaho Department of Environmental Quality as a nitrate priority area. The U.S. Geological Survey, in cooperation with the U.S. Air Force, began monitoring wells on the base in 1985, and currently monitors 25 wells for water levels and 17 wells for water quality, primarily nutrients. This report provides a summary of water-level and nitrate concentration data collected primarily between 2001 and 2013 and examines trends in those data. A Regional Kendall Test was run to combine results from all wells to determine an overall regional trend in water level. Groundwater levels declined at an average rate of about 1.08 feet per year. Nitrate concentration trends show that 3 wells (18 percent) are increasing in nitrate concentration trend, 3 wells (18 percent) show a decreasing nitrate concentration trend, and 11 wells (64 percent) show no nitrate concentration trend. Six wells (35 percent) currently exceed the U.S. Environmental Protection Agency's maximum contaminant limit of 10 milligrams per liter for nitrate (nitrite plus nitrate, measured as nitrogen).

  12. Measured concentrations of radioactive particles in air in the vicinity of the Anaconda Uranium Mill

    SciTech Connect

    Momeni, M H; Kisieleski, W E

    1980-02-01

    Concentrations of radioactive particles (U-238, Th-230, Ra-226, and Pb-210) in air were measured in the vicinity of the Anaconda Uranium Mill, Bluewater, New Mexico. Airborne particles were collected at three stations for about two-thirds of a year using a continuous collection method at a sampling rate of 10 L/min, and also were measured in monthly composites collected periodically at four stations using high volume air samplers at a sampling rate of 1400 L/min. The ratios of concentrations of each radionuclide to the concentrations of U-238 indicate that the concentrations of the radionuclides are influenced principally by the proximity of the major sources of emission and the direction of the wind. In all cases, the concentration of Pb-210 exceeded that of U-238. The ratio of Pb-210/U-238 was 12.3 and 13.3 for stations dominated by the emissions from the tailings and ore pads, but was only 1.6 for the station dominated by the yellowcake stack emission. The ratio of the radionuclide concentrations measured by the two methods of sample collection was between 0.8 and 1.2 for uranium, radium, and lead at station 104, but was 0.28 to 1.7 for thorium, radium, and lead at stations 101 and 102. The average concentrations calculated from the measurements made in this study suggest that releases from the Anaconda mill were made well within the existing limits of the maximum permissible concentrations for inhalation exposure of the general public.

  13. Process independent automated sizing methodology for current steering DAC

    NASA Astrophysics Data System (ADS)

    Vural, R. A.; Kahraman, N.; Erkmen, B.; Yildirim, T.

    2015-10-01

    This study introduces a process independent automated sizing methodology based on general regression neural network (GRNN) for current steering complementary metal-oxide semiconductor (CMOS) digital-to-analog converter (DAC) circuit. The aim is to utilise circuit structures designed with previous process technologies and to synthesise circuit structures for novel process technologies in contrast to other modelling researches that consider a particular process technology. The simulations were performed using ON SEMI 1.5 µm, ON SEMI 0.5 µm and TSMC 0.35 µm technology process parameters. Eventually, a high-dimensional database was developed consisting of transistor sizes of DAC designs and corresponded static specification errors obtained from simulation results. The key point is that the GRNN was trained with the data set including the simulation results of ON-SEMI 1.5 µm and 0.5 µm technology parameters and the test data were constituted with only the simulation results of TSMC 0.35 µm technology parameters that had not been applied to GRNN for training beforehand. The proposed methodology provides the channel lengths and widths of all transistors for a newer technology when the designer sets the numeric values of DAC static output specifications as Differential Non-linearity error, Integral Non-linearity error, monotonicity and gain error as the inputs of the network.

  14. Effects of light intensity and air velocity on air temperature, water vapor pressure, and CO2 concentration inside a plant canopy under an artificial lighting condition.

    PubMed

    Kitaya, Y; Shibuya, T; Kozai, T; Kubota, C

    1998-01-01

    In order to characterize environmental variables inside a plant canopy under artificial lighting in the CELSS, we investigated the effects of light intensity and air velocity on air temperature, water vapor pressure, and CO2 concentration inside a plant canopy. Under a PPF of 500 micromoles m-2 s-1, air temperature was 2-3 degrees C higher, water vapor pressure was 0.6 kPa higher, and CO2 concentration was 25-35 micromoles mol-1 lower at heights ranging from 0 to 30 mm below the canopy than at a height 60 mm above the canopy. Increasing the PPF increased air temperature and water vapor pressure and decreased CO2 concentration inside the canopy. The air temperature was lower and the CO2 concentration was higher inside the canopy at an air velocity of 0.3 m s-1 than at an air velocity of 0.1 m s-1. The environmental variables inside the canopy under a high light intensity were characterized by higher air temperature, higher vapor pressure, and lower CO2 concentration than those outside the canopy.

  15. Air quality in postunification Erfurt, East Germany: associating changes in pollutant concentrations with changes in emissions.

    PubMed

    Ebelt, S; Brauer, M; Cyrys, J; Tuch, T; Kreyling, W G; Wichmann, H E; Heinrich, J

    2001-04-01

    The unification of East and West Germany in 1990 resulted in sharp decreases in emissions of major air pollutants. This change in air quality has provided an opportunity for a natural experiment to evaluate the health impacts of air pollution. We evaluated airborne particle size distribution and gaseous co-pollutant data collected in Erfurt, Germany, throughout the 1990s and assessed the extent to which the observed changes are associated with changes in the two major emission sources: coal burning for power production and residential heating, and motor vehicles. Continuous data for sulfur dioxide, total suspended particulates (TSP), nitric oxide, carbon monoxide, and meteorologic parameters were available for 1990-1999, and size-selective particle number and mass concentration measurements were made during winters of 1991 and 1998. We used hourly profiles of pollutants and linear regression analyses, stratified by year, weekday/weekend, and hour, using NO and SO(2) as markers of traffic- and heating-related combustion sources, respectively, to study the patterns of various particle size fractions. Supplementary data on traffic and heating-related sources were gathered to support hypotheses linking these sources with observed changes in ambient air pollution levels. Substantially decreased (19-91%) concentrations were observed for all pollutants, with the exception of particles in the 0.01-0.03 microm size range (representing the smallest ultrafine particles that were measured). The number concentration for these particles increased by 115% between 1991 and 1998. The ratio of these ultrafine particles to TSP also increased by more than 500%, indicating a dramatic change in the size distribution of airborne particles. Analysis of hourly concentration patterns indicated that in 1991, concentrations of SO(2) and larger particle sizes were related to residential heating with coal. These peaks were no longer evident in 1998 due to decreases in coal consumption and

  16. Air quality in postunification Erfurt, East Germany: associating changes in pollutant concentrations with changes in emissions.

    PubMed Central

    Ebelt, S; Brauer, M; Cyrys, J; Tuch, T; Kreyling, W G; Wichmann, H E; Heinrich, J

    2001-01-01

    The unification of East and West Germany in 1990 resulted in sharp decreases in emissions of major air pollutants. This change in air quality has provided an opportunity for a natural experiment to evaluate the health impacts of air pollution. We evaluated airborne particle size distribution and gaseous co-pollutant data collected in Erfurt, Germany, throughout the 1990s and assessed the extent to which the observed changes are associated with changes in the two major emission sources: coal burning for power production and residential heating, and motor vehicles. Continuous data for sulfur dioxide, total suspended particulates (TSP), nitric oxide, carbon monoxide, and meteorologic parameters were available for 1990-1999, and size-selective particle number and mass concentration measurements were made during winters of 1991 and 1998. We used hourly profiles of pollutants and linear regression analyses, stratified by year, weekday/weekend, and hour, using NO and SO(2) as markers of traffic- and heating-related combustion sources, respectively, to study the patterns of various particle size fractions. Supplementary data on traffic and heating-related sources were gathered to support hypotheses linking these sources with observed changes in ambient air pollution levels. Substantially decreased (19-91%) concentrations were observed for all pollutants, with the exception of particles in the 0.01-0.03 microm size range (representing the smallest ultrafine particles that were measured). The number concentration for these particles increased by 115% between 1991 and 1998. The ratio of these ultrafine particles to TSP also increased by more than 500%, indicating a dramatic change in the size distribution of airborne particles. Analysis of hourly concentration patterns indicated that in 1991, concentrations of SO(2) and larger particle sizes were related to residential heating with coal. These peaks were no longer evident in 1998 due to decreases in coal consumption and

  17. Spatial and temporal distribution of pesticide air concentrations in Canadian agricultural regions

    NASA Astrophysics Data System (ADS)

    Yao, Yuan; Tuduri, Ludovic; Harner, Tom; Blanchard, Pierrette; Waite, Don; Poissant, Laurier; Murphy, Clair; Belzer, Wayne; Aulagnier, Fabien; Li, Yi-Fan; Sverko, Ed

    The Canadian Pesticide Air Sampling Campaign was initiated in 2003 to assess atmospheric levels of pesticides, especially currently used pesticides (CUPs) in agricultural regions across Canada. In the first campaign during the spring to summer of 2003, over 40 pesticides were detected. The spatial and temporal distribution of pesticides in the Canadian atmosphere was shown to reflect the pesticide usage in each region. Several herbicides including triallate, bromoxynil, MCPA, 2,4-D, dicamba, trifluralin and ethalfluralin were detected at highest levels at Bratt's Lake, SK in the prairie region. Strong relationships between air concentrations and dry depositions were observed at this site. Although no application occurred in the Canadian Prairies in 2003, high air concentrations of lindane ( γ-hexachlorocyclohexane) were still observed at Bratt's Lake and Hafford, SK. Two fungicides (chlorothalonil and metalaxyl) and two insecticides (endosulfan and carbofuran) were measured at highest levels at Kensington, PEI. Maximum concentrations of chlorpyrifos and metolachlor were found at St. Anicet, QC. The southern Ontario site, Egbert showed highest concentration of alachlor. Malathion was detected at the highest level at the west coast site, Abbotsford, BC. In case of legacy chlorinated insecticides, high concentrations of DDT, DDE and dieldrin were detected in British Columbia while α-HCH and HCB were found to be fairly uniform across the country. Chlordane was detected in Ontario, Québec and Prince Edward Island. This study demonstrates that the sources for the observed atmospheric occurrence of pesticides include local current pesticide application, volatilization of pesticide residues from soil and atmospheric transport. In many instances, these data represent the first measurements for certain pesticides in a given part of Canada.

  18. Modeling of air pollutant concentrations in an industrial region of Turkey.

    PubMed

    Tuygun, Gizem Tuna; Altuğ, Hicran; Elbir, Tolga; Gaga, Eftade E

    2017-02-03

    The hourly SO2 and PM10 concentrations in ambient air of the Kutahya city located at the western part of Turkey have exceeded the air quality limits in winter months since several years. The region has major industrial plants including lignite-fired power plants and open-cast mining activities, residential areas, and traffic sources. To obtain and quantify the sector-wise anthropogenic emissions and spatial distribution of the major pollutants including SO2, NO x , PM10, and CO, a comprehensive emission inventory with 1-km spatial resolution was prepared for the year of 2014, and the AERMOD dispersion model was used to predict ambient air concentrations in a domain of 140 km by 110 km. Validation of the model results was also done referring to in situ routine measurements at two monitoring stations located in the study area. Total emissions of SO2, PM10, NO x , and CO in the study area were calculated as 64,399, 9770, 24,627, and 29,198 tons/year, respectively. The results showed that industrial plants were the largest sources of SO2, NO x , and PM10 emissions, while residential heating and road traffic were the most contributing sectors for CO emissions. Three major power plants in the region with total annual lignite consumption of 10 million tons per year were main sources of high SO2 concentrations, while high PM10 concentrations mainly originated from two major open-cast lignite mines. Major contributors of high NO x and CO concentrations were traffic including highways and urban streets, and residential heating with high lignite consumption in urban areas. Results of the dispersion model run with the emission inventory resulted in partially high index of agreement (0.75) with SO2 measured in the urban station within the modeled area.

  19. Predicting soil fumigant air concentrations under regional and diverse agronomic conditions.

    PubMed

    Cryer, Steven A

    2005-01-01

    SOFEA (SOil Fumigant Exposure Assessment system; Dow AgroSciences, Indianapolis, IN) is a new stochastic numerical modeling tool for evaluating and managing human inhalation exposure potential associated with the use of soil fumigants. SOFEA calculates fumigant concentrations in air arising from volatility losses from treated fields for large agricultural regions using multiple transient source terms (treated fields), geographical information systems (GIS) information, agronomic specific variables, user-specified buffer zones, and field reentry intervals. A modified version of the USEPA Industrial Source Complex Short Term model (ISCST3) is used for air dispersion calculations. Weather information, field size, application date, application rate, application type, soil incorporation depth, pesticide degradation rates in air, tarp presence, field retreatment, and other sensitive parameters are varied stochastically using Monte Carlo techniques to mimic region and crop specific agronomic practices. Regional land cover, elevation, and population information can be used to refine source placement (treated fields), dispersion calculations, and risk assessments. This paper describes the technical algorithms of SOFEA and offers comparisons of simulation predictions for the soil fumigant 1,3-dichloropropene (1,3-D) to actual regional air monitoring measurements from Kern, California. Comparison of simulation results to daily air monitoring observations is remarkable over the entire concentration distribution (average percent deviation of 44% and model efficiency of 0.98), especially considering numerous inputs such as meteorological conditions for SOFEA were unavailable and approximated by neighboring regions. Both current and anticipated and/or forecasted fumigant scenarios can be simulated using SOFEA to provide risk managers and product stewards the necessary information to make sound regulatory decisions regarding the use of soil fumigants in agriculture.

  20. Benzo(a)pyrene in Europe: Ambient air concentrations, population exposure and health effects.

    PubMed

    Guerreiro, C B B; Horálek, J; de Leeuw, F; Couvidat, F

    2016-07-01

    This study estimated current benzo(a)pyrene (BaP) concentration levels, population exposure and potential health impacts of exposure to ambient air BaP in Europe. These estimates were done by combining the best available information from observations and chemical transport models through the use of spatial interpolation methods. Results show large exceedances of the European target value for BaP in 2012 over large areas, particularly in central-eastern Europe. Results also show large uncertainties in the concentration estimates in regions with a few or no measurement stations. The estimation of the population exposure to BaP concentrations and its health impacts was limited to 60% of the European population, covering only the modelled areas which met the data quality requirement for modelling of BaP concentrations set by the European directive 2004/107/EC. The population exposure estimate shows that 20% of the European population is exposed to BaP background ambient concentrations above the EU target value and only 7% live in areas with concentrations under the estimated acceptable risk level of 0.12 ng m(-3). This exposure leads to an estimated 370 lung cancer incidences per year, for the 60% of the European population included in the estimation. Emissions of BaP have increased in the last decade with the increase in emissions from household combustion of biomass. At the same time, climate mitigation policies are promoting the use of biomass burning for domestic heating. The current study shows that there is a need for more BaP measurements in areas of low measurement density, particularly where high concentrations are expected, e.g. in Romania, Bulgaria, and other Balkan states. Furthermore, this study shows that the health risk posed by PAH exposure calls for better coordination between air quality and climate mitigation policies in Europe.

  1. Criteria and methods for establishing maximum permissible concentrations of air pollution

    PubMed Central

    Rjazanov, V. A.

    1965-01-01

    The article describes experience in the USSR in establishing standards for air pollution control. The author emphasizes that health considerations must be the main criterion in deciding permissible concentrations, which constitute the “hygienic” standards ultimately to be achieved. Economic and technological reasons may dictate temporary “sanitary” standards, which modify the requirements for a limited period. “Technological” standards relate to the economic and technological consequences of air pollution and do not concern health. The maximum permissible concentrations of toxic substances used in toxicology and industrial hygiene are not sufficiently stringent for general use, and control standards are therefore based on the results of tests carried out on animals and human subjects. Tests on animals show that certain concentrations of toxic substances cause functional changes (e.g., in higher nervous activity, cholinesterase activity, and excretion of coproporphyrin) as well as a number of protective adaptational reactions. The results are used to establish maximum permissible concentrations of pollutants within a 24-hour period. Tests on human volunteers provide a basis for determining the maximum average concentrations at a given time. Reactions to odorous substances give the olfactory threshold and the level of concentration causing respiratory and visual reflexes, as well as subsensory effects such as changes in light sensitivity and in the activity of the cerebral cortex. Morbidity statistics also provide evidence of harmful pollution, but cannot serve as a basis for establishing maximum permissible concentrations, which should aim not only at preventing illness but also at avoiding pathological and adaptational reactions. PMID:14315711

  2. Assessment of workplace air concentrations of formaldehyde during and before working hours in medical facilities

    PubMed Central

    HIGASHIKUBO, Ichiro; MIYAUCHI, Hiroyuki; YOSHIDA, Satoru; TANAKA, Shinsuke; MATSUOKA, Mitsunori; ARITO, Heihachiro; ARAKI, Akihiro; SHIMIZU, Hidesuke; SAKURAI, Haruhiko

    2017-01-01

    Workplace air concentrations of formaldehyde (FA) in medical facilities where FA and FA-treated organs were stored and handled were measured before and during working hours and assessed by the official method specified by Work Environment Measurement Law. Sixty-percent of the total facilities examined were judged as inappropriately controlled work environment. The concentrations of FA before working hours by spot sampling were found to exceed 0.1 ppm in some facilities, and tended to increase with increasing volume of containers storing FA and FA-treated materials. Regression analysis revealed that logarithmic concentrations of FA during working hours by the Law-specified analytical method were highly correlated with those before working hours by spot sampling, suggesting the importance for appropriate storing methods of FA and FA-treated materials. The concentrations of FA during working hours are considered to be lowered by effective ventilation of FA-contaminated workplace air and appropriate storage of FA and FA-treated materials in plastic containers in the medical facilities. In particular, such improvement by a local exhaust ventilation system and tightly-sealed containment of FA-treated material were urgently needed for the dissecting room where FA-treated cadavers were prepared and handled for a gross anatomy course in a medical school. PMID:28090065

  3. Nitrogen potential recovery and concentration of ammonia from swine manure using electrodialysis coupled with air stripping.

    PubMed

    Ippersiel, D; Mondor, M; Lamarche, F; Tremblay, F; Dubreuil, J; Masse, L

    2012-03-01

    The practice of intensive animal production in certain areas has resulted in excessive manure production for the available regional land base. Consequently, there is a need to develop treatment technologies to recover the valuable nutrients that manure contains so that the resulting product can be transported and used as fertilizer on agricultural land. The project presented here used electrodialysis in a dilution/concentration configuration to transfer the manure ammonia in the diluate solution by electromigration to an adjacent solution separated by an ion-exchange membrane under the driving force of an electrical potential. Then, air stripping from the electrodialysis-obtained concentrate solution without pH modification was used to isolate the ammonia in an acidic solution. An optimal process operating voltage of 17.5 V was first determined on the basis of current efficiency and total energy consumption. During the process, the swine manure pH varied from 8.5 to 8.2, values favourable for NH(4)(+) electromigration. Total ammonia nitrogen reached 21,352 mg/L in the concentrate solution, representing approximately seven times the concentration in the swine manure. Further increases in concentration were limited by water transfer from the diluate solution due to electroosmosis and osmosis. Applying vacuum to the concentrate reservoir was found to be more efficient than direct concentrate solution aeration for NH(3) recuperation in the acid trap, given that the ammonia recuperated under vacuum represented 14.5% of the theoretical value of the NH(3) present in the concentrate solution as compared to 6.2% for aeration. However, an excessively low concentrate solution pH (8.6-8.3) limited NH(3)volatilization toward the acid trap. These results suggest that the concentrate solution pH needs to be raised to promote the volatile NH(3) form of total ammonia nitrogen.

  4. Combining regression analysis and air quality modelling to predict benzene concentration levels

    NASA Astrophysics Data System (ADS)

    Vlachokostas, Ch.; Achillas, Ch.; Chourdakis, E.; Moussiopoulos, N.

    2011-05-01

    State of the art epidemiological research has found consistent associations between traffic-related air pollution and various outcomes, such as respiratory symptoms and premature mortality. However, many urban areas are characterised by the absence of the necessary monitoring infrastructure, especially for benzene (C 6H 6), which is a known human carcinogen. The use of environmental statistics combined with air quality modelling can be of vital importance in order to assess air quality levels of traffic-related pollutants in an urban area in the case where there are no available measurements. This paper aims at developing and presenting a reliable approach, in order to forecast C 6H 6 levels in urban environments, demonstrated for Thessaloniki, Greece. Multiple stepwise regression analysis is used and a strong statistical relationship is detected between C 6H 6 and CO. The adopted regression model is validated in order to depict its applicability and representativeness. The presented results demonstrate that the adopted approach is capable of capturing C 6H 6 concentration trends and should be considered as complementary to air quality monitoring.

  5. Modeling breathing-zone concentrations of airborne contaminants generated during compressed air spray painting.

    PubMed

    Flynn, M R; Gatano, B L; McKernan, J L; Dunn, K H; Blazicko, B A; Carlton, G N

    1999-01-01

    This paper presents a mathematical model to predict breathing-zone concentrations of airborne contaminants generated during compressed air spray painting in cross-flow ventilated booths. The model focuses on characterizing the generation and transport of overspray mist. It extends previous work on conventional spray guns to include exposures generated by HVLP guns. Dimensional analysis and scale model wind-tunnel studies are employed using non-volatile oils, instead of paint, to produce empirical equations for estimating exposure to total mass. Results indicate that a dimensionless breathing zone concentration is a nonlinear function of the ratio of momentum flux of air from the spray gun to the momentum flux of air passing through the projected area of the worker's body. The orientation of the spraying operation within the booth is also very significant. The exposure model requires an estimate of the contaminant generation rate, which is approximated by a simple impactor model. The results represent an initial step in the construction of more realistic models capable of predicting exposure as a mathematical function of the governing parameters.

  6. High Concentrations of Organic Contaminants in Air from Ship Breaking Activities in Chittagong, Bangladesh.

    PubMed

    Nøst, Therese H; Halse, Anne K; Randall, Scott; Borgen, Anders R; Schlabach, Martin; Paul, Alak; Rahman, Atiqur; Breivik, Knut

    2015-10-06

    The beaches on the coast of Chittagong in Bangladesh are one of the most intense ship breaking areas in the world. The aim of the study was to measure the concentrations of organic contaminants in the air in the city of Chittagong, including the surrounding ship breaking areas using passive air samplers (N = 25). The compounds detected in the highest amounts were the polycyclic aromatic hydrocarbons (PAHs) and short-chain chlorinated paraffins (SCCPs), whereas dichlorodiphenyltrichloroethanes (DDTs), hexachlorobenzene (HCB), and polychlorinated biphenyls (PCBs) were several orders of magnitude lower in comparison. PCBs, PAHs, and HCB were highest at sites near the ship breaking activities, whereas DDTs and SCCPs were higher in the urban areas. Ship breaking activities likely act as atmospheric emission sources of PCBs, PAHs, and HCB, thus adding to the international emphasis on responsible recycling of ships. Concentrations of PAHs, PCBs, DDTs, HCB, and SCCPs in ambient air in Chittagong are high in comparison to those found in similar studies performed in other parts of Asia. Estimated toxic equivalent quotients indicate elevated human health risks caused by inhalation of PAHs at most sites.

  7. Control of aerosol contaminants in indoor air: combining the particle concentration reduction with microbial inactivation.

    PubMed

    Grinshpun, Sergey A; Adhikari, Atin; Honda, Takeshi; Kim, Ki Youn; Toivola, Mika; Rao, K S Ramchander; Reponen, Tiina

    2007-01-15

    An indoor air purification technique, which combines unipolar ion emission and photocatalytic oxidation (promoted by a specially designed RCI cell), was investigated in two test chambers, 2.75 m3 and 24.3 m3, using nonbiological and biological challenge aerosols. The reduction in particle concentration was measured size selectively in real-time, and the Air Cleaning Factor and the Clean Air Delivery Rate (CADR) were determined. While testing with virions and bacteria, bioaerosol samples were collected and analyzed, and the microorganism survival rate was determined as a function of exposure time. We observed that the aerosol concentration decreased approximately 10 to approximately 100 times more rapidly when the purifier operated as compared to the natural decay. The data suggest that the tested portable unit operating in approximately 25 m3 non-ventilated room is capable to provide CADR-values more than twice as great than the conventional closed-loop HVAC system with a rating 8 filter. The particle removal occurred due to unipolar ion emission, while the inactivation of viable airborne microorganisms was associated with photocatalytic oxidation. Approximately 90% of initially viable MS2 viruses were inactivated resulting from 10 to 60 min exposure to the photocatalytic oxidation. Approximately 75% of viable B. subtilis spores were inactivated in 10 min, and about 90% or greater after 30 min. The biological and chemical mechanisms that led to the inactivation of stress-resistant airborne viruses and bacterial spores were reviewed.

  8. Effect of geocoding errors on traffic-related air pollutant exposure and concentration estimates

    PubMed Central

    Ganguly, Rajiv; Batterman, Stuart; Isakov, Vlad; Snyder, Michelle; Breen, Michael; Brakefield-Caldwell, Wilma

    2015-01-01

    Exposure to traffic-related air pollutants is highest very near roads, and thus exposure estimates are sensitive to positional errors. This study evaluates positional and PM2.5 concentration errors that result from the use of automated geocoding methods and from linearized approximations of roads in link-based emission inventories. Two automated geocoders (Bing Map and ArcGIS) along with handheld GPS instruments were used to geocode 160 home locations of children enrolled in an air pollution study investigating effects of traffic-related pollutants in Detroit, Michigan. The average and maximum positional errors using the automated geocoders were 35 and 196 m, respectively. Comparing road edge and road centerline, differences in house-to-highway distances averaged 23 m and reached 82 m. These differences were attributable to road curvature, road width and the presence of ramps, factors that should be considered in proximity measures used either directly as an exposure metric or as inputs to dispersion or other models. Effects of positional errors for the 160 homes on PM2.5 concentrations resulting from traffic-related emissions were predicted using a detailed road network and the RLINE dispersion model. Concentration errors averaged only 9%, but maximum errors reached 54% for annual averages and 87% for maximum 24-h averages. Whereas most geocoding errors appear modest in magnitude, 5% to 20% of residences are expected to have positional errors exceeding 100 m. Such errors can substantially alter exposure estimates near roads because of the dramatic spatial gradients of traffic-related pollutant concentrations. To ensure the accuracy of exposure estimates for traffic-related air pollutants, especially near roads, confirmation of geocoordinates is recommended. PMID:25670023

  9. Effect of geocoding errors on traffic-related air pollutant exposure and concentration estimates.

    PubMed

    Ganguly, Rajiv; Batterman, Stuart; Isakov, Vlad; Snyder, Michelle; Breen, Michael; Brakefield-Caldwell, Wilma

    2015-01-01

    Exposure to traffic-related air pollutants is highest very near roads, and thus exposure estimates are sensitive to positional errors. This study evaluates positional and PM2.5 concentration errors that result from the use of automated geocoding methods and from linearized approximations of roads in link-based emission inventories. Two automated geocoders (Bing Map and ArcGIS) along with handheld GPS instruments were used to geocode 160 home locations of children enrolled in an air pollution study investigating effects of traffic-related pollutants in Detroit, Michigan. The average and maximum positional errors using the automated geocoders were 35 and 196 m, respectively. Comparing road edge and road centerline, differences in house-to-highway distances averaged 23 m and reached 82 m. These differences were attributable to road curvature, road width and the presence of ramps, factors that should be considered in proximity measures used either directly as an exposure metric or as inputs to dispersion or other models. Effects of positional errors for the 160 homes on PM2.5 concentrations resulting from traffic-related emissions were predicted using a detailed road network and the RLINE dispersion model. Concentration errors averaged only 9%, but maximum errors reached 54% for annual averages and 87% for maximum 24-h averages. Whereas most geocoding errors appear modest in magnitude, 5% to 20% of residences are expected to have positional errors exceeding 100 m. Such errors can substantially alter exposure estimates near roads because of the dramatic spatial gradients of traffic-related pollutant concentrations. To ensure the accuracy of exposure estimates for traffic-related air pollutants, especially near roads, confirmation of geocoordinates is recommended.

  10. VOCs Emissions from Multiple Wood Pellet Types and Concentrations in Indoor Air

    PubMed Central

    Soto-Garcia, Lydia; Ashley, William J.; Bregg, Sandar; Walier, Drew; LeBouf, Ryan; Hopke, Philip K.; Rossner, Alan

    2016-01-01

    Wood pellet storage safety is an important aspect for implementing woody biomass as a renewable energy source. When wood pellets are stored indoors in large quantities (tons) in poorly ventilated spaces in buildings, such as in basements, off-gassing of volatile organic compounds (VOCs) can significantly affect indoor air quality. To determine the emission rates and potential impact of VOC emissions, a series of laboratory and field measurements were conducted using softwood, hardwood, and blended wood pellets manufactured in New York. Evacuated canisters were used to collect air samples from the headspace of drums containing pellets and then in basements and pellet storage areas of homes and small businesses. Multiple peaks were identified during GC/MS and GC/FID analysis, and four primary VOCs were characterized and quantified: methanol, pentane, pentanal, and hexanal. Laboratory results show that total VOCs (TVOCs) concentrations for softwood (SW) were statistically (p < 0.02) higher than blended or hardwood (HW) (SW: 412 ± 25; blended: 203 ± 4; HW: 99 ± 8, ppb). The emission rate from HW was the fastest, followed by blended and SW, respectively. Emissions rates were found to range from 10−1 to 10−5 units, depending upon environmental factors. Field measurements resulted in airborne concentrations ranging from 67 ± 8 to 5000 ± 3000 ppb of TVOCs and 12 to 1500 ppb of aldehydes, with higher concentrations found in a basement with a large fabric bag storage unit after fresh pellet delivery and lower concentrations for aged pellets. These results suggest that large fabric bag storage units resulted in a substantial release of VOCs into the building air. Occupants of the buildings tested discussed concerns about odor and sensory irritation when new pellets were delivered. The sensory response was likely due to the aldehydes. PMID:27022205

  11. Cleaning Products and Air Fresheners: Emissions and ResultingConcentrations of Glycol Ethers and Terpenoids

    SciTech Connect

    Singer, Brett C.; Destaillat, Hugo; Hodgson, Alfred T.; Nazaroff,William W.

    2005-08-01

    Experiments were conducted to quantify emissions and concentrations of glycol ethers and terpenoids from cleaning product and air freshener use in a 50-m{sup 3} room ventilated at {approx}0.5 h{sup -1}. Five cleaning products were applied full-strength (FS); three were additionally used in dilute solution. FS application of pine-oil cleaner (POC) yielded 1-h concentrations of 10-1300 {micro}g m{sup -3} for individual terpenoids, including {alpha}-terpinene (90-120), d-limonene (1000-1100), terpinolene (900-1300), and {alpha}-terpineol (260-700). One-hour concentrations of 2-butoxyethanol and/or dlimonene were 300-6000 {micro}g m{sup -3} after FS use of other products. During FS application including rinsing with sponge and wiping with towels, fractional emissions (mass volatilized/dispensed) of 2-butoxyethanol and d-limonene were 50-100% with towels retained, {approx}25-50% when towels were removed after cleaning. Lower fractions (2-11%) resulted from dilute use. Fractional emissions of terpenes from FS use of POC were {approx}35-70% with towels retained, 20-50% with towels removed. During floor cleaning with dilute solution of POC, 7-12% of dispensed terpenes were emitted. Terpene alcohols were emitted at lower fractions: 7-30% (FS, towels retained), 2-9% (FS, towels removed), and 2-5% (dilute). During air-freshener use, d-limonene, dihydromyrcenol, linalool, linalyl acetate, and {beta}-citronellol were emitted at 35-180 mg d{sup -1} over three days while air concentrations averaged 30-160 {micro}g m{sup -3}.

  12. Derivation and implementation of an annual limit on intake and a derived air concentration value for uranium mill tailings

    SciTech Connect

    Reif, R.H.; Andrews, D.W.

    1995-06-01

    Monitoring workers and work areas at the Department of Energy Uranium Mill Tailings Remedial Action Project sites is complex because all radionuclides in the {sup 238}U and {sup 235}U decay chains may be present in an airborne uranium mill tillings matrix. Previous monitoring practices involved isotopic analysis of the air filter to determine the activity of each radionuclide of concern and comparing the results to the specified derived air concentration. The annual limit on intake and derived air concentration values have been derived here for the uranium mill tailings matrix to simplify the procedure for evaluation of air monitoring results and assessment of the need for individual monitoring. Implementation of the derived air concentration for uranium mill tailings involves analyzing air samples for long-lived gross alpha activity and comparing the activity concentration to the derived air concentration. Health physics decisions regarding assessment of airborne concentrations is more cost-effective because isotopic analysis of air samples is not necessary. 12 refs., 2 tabs.

  13. Reduction of radon progeny concentration by means of an air cleaner. Report no. MRL 90-143(TR)

    SciTech Connect

    Bigu, J.; Edwardson, E.

    1990-01-01

    There are a variety of airborne radionuclides found in working and living environments which at sufficiently elevated concentration levels can pose a potential hazard to human health. This report describes the use of a device which operates on a 'hybrid' technique consisting of air filtration, electrostatic deposition, and turbulent air mixing to reduce the concentration levels of Rn222 progeny levels in air. Experiments were carried out in Rn222/Rn222 progeny atmospheres when the air cleaner was operating and when it was turned off.

  14. Elevated concentrations of endotoxin in indoor air due to cigarette smoking.

    PubMed

    Sebastian, Aleksandra; Pehrson, Christina; Larsson, Lennart

    2006-05-01

    Exposure to environmental tobacco smoke (ETS) is an important worldwide public health issue. The present study demonstrates that cigarette smoke can be a major source of endotoxin (lipopolysaccharide, LPS) in indoor environments. Gas-chromatography/mass-spectrometry was used to determine 3-hydroxy fatty acids as markers of endotoxin in air-borne house dust in homes of smokers and non-smokers. Air concentrations of endotoxin were 4-63 times higher in rooms of smoking students than in identical rooms of non-smoking students. The fact that cigarette smoke contains large amounts of endotoxin may partly explain the high prevalence of respiratory disorders among smokers and may also draw attention to a hitherto neglected risk factor of ETS.

  15. Yield-Ensuring DAC-Embedded Opamp Design Based on Accurate Behavioral Model Development

    NASA Astrophysics Data System (ADS)

    Jang, Yeong-Shin; Nguyen, Hoai-Nam; Ryu, Seung-Tak; Lee, Sang-Gug

    An accurate behavioral model of a DAC-embedded opamp (DAC-opamp) is developed for a yield-ensuring LCD column driver design. A lookup table for the V-I curve of the unit differential pair in the DAC-opamp is extracted from a circuit simulation and is later manipulated through a random error insertion. Virtual ground assumption simplifies the output voltage estimation algorithm. The developed behavioral model of a 5-bit DAC-opamp shows good agreement with the circuit level simulation with less than 5% INL difference.

  16. Determination of lead, cations, and anions concentration in indoor and outdoor air at the primary schools in Kuala Lumpur.

    PubMed

    Awang, Normah; Jamaluddin, Farhana

    2014-01-01

    This study was carried out to determine the concentration of lead (Pb), anions, and cations at six primary schools located around Kuala Lumpur. Low volume sampler (MiniVol PM10) was used to collect the suspended particulates in indoor and outdoor air. Results showed that the concentration of Pb in indoor air was in the range of 5.18 ± 1.08 μg/g-7.01 ± 0.08 μg/g. All the concentrations of Pb in indoor air were higher than in outdoor air at all sampling stations. The concentrations of cations and anions were higher in outdoor air than in indoor air. The concentration of Ca(2+) (39.51 ± 5.01 mg/g-65.13 ± 9.42 mg/g) was the highest because the cation existed naturally in soil dusts, while the concentrations of NO3 (-) and SO4 (2-) were higher in outdoor air because there were more sources of exposure for anions in outdoor air, such as highly congested traffic and motor vehicles emissions. In comparison, the concentration of NO3 (-) (29.72 ± 0.31 μg/g-32.00 ± 0.75 μg/g) was slightly higher than SO4 (2-). The concentrations of most of the parameters in this study, such as Mg(2+), Ca(2+), NO3 (-), SO4 (2-), and Pb(2+), were higher in outdoor air than in indoor air at all sampling stations.

  17. Modeling VOC emissions and air concentrations from the Exxon Valdez oil spill

    SciTech Connect

    Hanna, S.R. ); Drivas, P.J. )

    1993-03-01

    During the two-week period following the Exxon Valdez oil spill in March 1989 in Prince William Sound, Alaska, toxic volatile organic compounds (VOCs) evaporated from the surface of the oil spill and were transported and dispersed throughout the region. To estimate the air concentrations of these VOCs, emissions and dispersion modeling was conducted for each hour during the first two weeks of the spill. A multicomponent evaporative emissions model was developed and applied to the oil spill; the model considered the evaporation of 15 specific compounds, including benzene and toluene. Both mass transfer from the surface of the spill and diffusion through the oil layer were considered in the emissions model. Maximum emissions of toluene were calculated to equal about 20,000 kg/hr, or about 5 g/m[sup 2] hr, at a time of eight hours after the initial oil spill. Meteorological data were acquired from sources and used to estimate hourly-averaged wind velocity over the spill. Air concentrations of specific components were calculated using the ATDL area source diffusion model and the Offshore and Coastal Dispersion (OCD) model. Maximum hourly-averaged concentrations were predicted not to exceed 10 ppmv for any compound. 24 refs., 6 figs., 4 tabs.

  18. OPENING REMARKS: SciDAC: Scientific Discovery through Advanced Computing

    NASA Astrophysics Data System (ADS)

    Strayer, Michael

    2005-01-01

    Good morning. Welcome to SciDAC 2005 and San Francisco. SciDAC is all about computational science and scientific discovery. In a large sense, computational science characterizes SciDAC and its intent is change. It transforms both our approach and our understanding of science. It opens new doors and crosses traditional boundaries while seeking discovery. In terms of twentieth century methodologies, computational science may be said to be transformational. There are a number of examples to this point. First are the sciences that encompass climate modeling. The application of computational science has in essence created the field of climate modeling. This community is now international in scope and has provided precision results that are challenging our understanding of our environment. A second example is that of lattice quantum chromodynamics. Lattice QCD, while adding precision and insight to our fundamental understanding of strong interaction dynamics, has transformed our approach to particle and nuclear science. The individual investigator approach has evolved to teams of scientists from different disciplines working side-by-side towards a common goal. SciDAC is also undergoing a transformation. This meeting is a prime example. Last year it was a small programmatic meeting tracking progress in SciDAC. This year, we have a major computational science meeting with a variety of disciplines and enabling technologies represented. SciDAC 2005 should position itself as a new corner stone for Computational Science and its impact on science. As we look to the immediate future, FY2006 will bring a new cycle to SciDAC. Most of the program elements of SciDAC will be re-competed in FY2006. The re-competition will involve new instruments for computational science, new approaches for collaboration, as well as new disciplines. There will be new opportunities for virtual experiments in carbon sequestration, fusion, and nuclear power and nuclear waste, as well as collaborations

  19. Use of dust fall filters as passive samplers for metal concentrations in air for communities near contaminated mine tailings.

    PubMed

    Beamer, P I; Sugeng, A J; Kelly, M D; Lothrop, N; Klimecki, W; Wilkinson, S T; Loh, M

    2014-05-01

    Mine tailings are a source of metal exposures in many rural communities. Multiple air samples are necessary to assess the extent of exposures and factors contributing to these exposures. However, air sampling equipment is costly and requires trained personnel to obtain measurements, limiting the number of samples that can be collected. Simple, low-cost methods are needed to allow for increased sample collection. The objective of our study was to assess if dust fall filters can serve as passive air samplers and be used to characterize potential exposures in a community near contaminated mine tailings. We placed filters in cylinders, concurrently with active indoor air samplers, in 10 occupied homes. We calculated an estimated flow rate by dividing the mass on each dust fall filter by the bulk air concentration and the sampling duration. The mean estimated flow rate for dust fall filters was significantly different during sampling periods with precipitation. The estimated flow rate was used to estimate metal concentration in the air of these homes, as well as in 31 additional homes in another rural community impacted by contaminated mine tailings. The estimated air concentrations had a significant linear association with the measured air concentrations for beryllium, manganese and arsenic (p < 0.05), whose primary source in indoor air is resuspended soil from outdoors. In the second rural community, our estimated metal concentrations in air were comparable to active air sampling measurements taken previously. This passive air sampler is a simple low-cost method to assess potential exposures near contaminated mining sites.

  20. Particulate matter concentration in ambient air and its effects on lung functions among residents in the National Capital Region, India.

    PubMed

    Kesavachandran, C; Pangtey, B S; Bihari, V; Fareed, M; Pathak, M K; Srivastava, A K; Mathur, N

    2013-02-01

    The World Health Organization has estimated that air pollution is responsible for 1.4 % of all deaths and 0.8 % of disability-adjusted life years. NOIDA, located at the National Capital Region, India, was declared as one of the critically air-polluted areas by the Central Pollution Control Board of the Government of India. Studies on the relationship of reduction in lung functions of residents living in areas with higher concentrations of particulate matter (PM) in ambient air were inconclusive since the subjects of most of the studies are hospital admission cases. Very few studies, including one from India, have shown the relationship of PM concentration and its effects of lung functions in the same location. Hence, a cross-sectional study was undertaken to study the effect of particulate matter concentration in ambient air on the lung functions of residents living in a critically air-polluted area in India. PM concentrations in ambient air (PM(1,) PM(2.5)) were monitored at residential locations and identified locations with higher (NOIDA) and lower concentrations (Gurgaon). Lung function tests (FEV(1), PEFR) were conducted using a spirometer in 757 residents. Both air monitoring and lung function tests were conducted on the same day. Significant negative linear relationship exists between higher concentrations of PM(1) with reduced FEV(1) and increased concentrations of PM(2.5) with reduced PEFR and FEV(1). The study shows that reductions in lung functions (PEFR and FEV(1)) can be attributed to higher particulate matter concentrations in ambient air. Decline in airflow obstruction in subjects exposed to high PM concentrations can be attributed to the fibrogenic response and associated airway wall remodeling. The study suggests the intervention of policy makers and stake holders to take necessary steps to reduce the emissions of PM concentrations, especially PM(1,) PM(2.5), which can lead to serious respiratory health concerns in residents.

  1. Contribution of ship emissions to the concentration and deposition of air pollutants in Europe

    NASA Astrophysics Data System (ADS)

    Aksoyoglu, Sebnem; Baltensperger, Urs; Prévôt, André S. H.

    2016-02-01

    Emissions from the marine transport sector are one of the least-regulated anthropogenic emission sources and contribute significantly to air pollution. Although strict limits were introduced recently for the maximum sulfur content in marine fuels in the SECAs (sulfur emission control areas) and in EU ports, sulfur emissions outside the SECAs and emissions of other components in all European maritime areas have continued to increase in the last two decades. We have used the air quality model CAMx (Comprehensive Air Quality Model with Extensions) with and without ship emissions for the year 2006 to determine the effects of international shipping on the annual as well as seasonal concentrations of ozone, primary and secondary components of PM2.5, and the dry and wet deposition of nitrogen and sulfur compounds in Europe. The largest changes in pollutant concentrations due to ship emissions were predicted for summer. Concentrations of particulate sulfate increased due to ship emissions in the Mediterranean (up to 60 %), the English Channel and the North Sea (30-35 %), while increases in particulate nitrate levels were found especially in the north, around the Benelux area (20 %), where there were high NH3 land-based emissions. Our model results showed that not only are the atmospheric concentrations of pollutants affected by ship emissions, but also depositions of nitrogen and sulfur compounds increase significantly along the shipping routes. NOx emissions from the ships, especially in the English Channel and the North Sea, cause a decrease in the dry deposition of reduced nitrogen at source regions by moving it from the gas phase to the particle phase which then contributes to an increase in the wet deposition at coastal areas with higher precipitation. In the western Mediterranean region, on the other hand, model results show an increase in the deposition of oxidized nitrogen (mostly HNO3) due to the ship traffic. Dry deposition of SO2 seems to be significant along

  2. Air pollutant concentrations near three Texas roadways, Part I: Ultrafine particles

    NASA Astrophysics Data System (ADS)

    Zhu, Yifang; Pudota, Jayanth; Collins, Donald; Allen, David; Clements, Andrea; DenBleyker, Allison; Fraser, Matt; Jia, Yuling; McDonald-Buller, Elena; Michel, Edward

    Vehicular emitted air pollutant concentrations were studied near three types of roadways in Austin, Texas: (1) State Highway 71 (SH-71), a heavily traveled arterial highway dominated by passenger vehicles; (2) Interstate 35 (I-35), a limited access highway north of Austin in Georgetown; and (3) Farm to Market Road 973 (FM-973), a heavily traveled surface roadway dominated by truck traffic. Air pollutants examined include carbon monoxide (CO), oxides of nitrogen (NO x), and carbonyl species in the gas-phase. In the particle phase, ultrafine particle (UFP) concentrations (diameter < 100 nm), fine particulate matter (PM 2.5, diameter < 2.5 μm) mass and carbon content and several particle-bound organics were examined. All roadways had an upwind stationary sampling location, one or two fixed downwind sample locations and a mobile monitoring platform that characterized pollutant concentrations fall-off with increased distance from the roadways. Data reported in this paper focus on UFP while other pollutants and near-roadway chemical processes are examined in a companion paper. Traffic volume, especially heavy-duty traffic, wind speed, and proximity to the road were found to be the most important factors determining UFP concentrations near the roadways. Since wind directions were not consistent during the sampling periods, distances along wind trajectories from the roadway to the sampling points were used to study the decay characteristics of UFPs. Under perpendicular wind conditions, for all studied roadway types, particle number concentrations increased dramatically moving from the upwind side to the downwind side. The elevated particle number concentrations decay exponentially with increasing distances from the roadway with sharp concentration gradients observed within 100-150 m, similar to previously reported studies. A single exponential decay curve was found to fit the data collected from all three roadways very well under perpendicular wind conditions. No

  3. Estimation of air concentrations and profiles for polychlorinated dibenzo-p-dioxins and dibenzofurans from calculated vegetation-air partition coefficients

    SciTech Connect

    Kjeller, L.O.; Rappe, C.; Jones, K.C.

    1995-12-31

    Air concentrations of vapor and particulate phase polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) are predicted by use of calculated plant-air partition coefficients. The plant-air interaction is reduced to an octanol-air distribution at equilibrium. Partition coefficients are deduced from the fugacity approach and calculated from congener group average data of solubility, vapor pressure and octanol-water partition coefficient. Calculated partition coefficients were used for prediction of the PCDD/F levels and congener profile in air from archived herbage collected pre- and post-1940. Before 1940 the air had a fly ash or combustion derived PCDD/F composition. After 1940 Hp and OCDD/F are superimposed on the combustion pattern, reflection of their release from the extensive use of polychlorinated compounds, notably penta chlorophenol, but also related compounds.

  4. Concentrations of polybrominated diphenyl ethers (PBDEs) in matched samples of human milk, dust and indoor air.

    PubMed

    Toms, Leisa-Maree L; Hearn, Laurence; Kennedy, Karen; Harden, Fiona; Bartkow, Michael; Temme, Christian; Mueller, Jochen F

    2009-08-01

    Polybrominated diphenyl ethers (PBDEs) are lipophilic, persistent pollutants found worldwide in environmental and human samples. Exposure pathways for PBDEs remain unclear but may include food, air and dust. The aim of this study was to conduct an integrated assessment of PBDE exposure and human body burden using 10 matched samples of human milk, indoor air and dust collected in 2007-2008 in Brisbane, Australia. In addition, temporal analysis was investigated comparing the results of the current study with PBDE concentrations in human milk collected in 2002-2003 from the same region. PBDEs were detected in all matrices and the median concentrations of BDEs -47 and -209 in human milk, air and dust were: 4.2 and 0.3 ng/g lipid; 25 and 7.8 pg/m(3); and 56 and 291 ng/g dust, respectively. Significant correlations were observed between the concentrations of BDE-99 in air and human milk (r=0.661, p=0.038) and BDE-153 in dust and BDE-183 in human milk (r=0.697, p=0.025). These correlations do not suggest causal relationships - there is no hypothesis that can be offered to explain why BDE-153 in dust and BDE-183 in milk are correlated. The fact that so few correlations were found in the data could be a function of the small sample size, or because additional factors, such as sources of exposure not considered or measured in the study, might be important in explaining exposure to PBDEs. There was a slight decrease in PBDE concentrations from 2002-2003 to 2007-2008 but this may be due to sampling and analytical differences. Overall, average PBDE concentrations from these individual samples were similar to results from pooled human milk collected in Brisbane in 2002-2003 indicating that pooling may be an efficient, cost-effective strategy of assessing PBDE concentrations on a population basis. The results of this study were used to estimate an infant's daily PBDE intake via inhalation, dust ingestion and human milk consumption. Differences in PBDE intake of individual

  5. Mixing layer height measurements determines influence of meteorology on air pollutant concentrations in urban area

    NASA Astrophysics Data System (ADS)

    Schäfer, Klaus; Blumenstock, Thomas; Bonn, Boris; Gerwig, Holger; Hase, Frank; Münkel, Christoph; Nothard, Rainer; von Schneidemesser, Erika

    2015-10-01

    Mixing layer height (MLH) is a key parameter to determine the influence of meteorological parameters upon air pollutants such as trace gas species and particulate concentrations near the surface. Meteorology, and MLH as a key parameter, affect the budget of emission source strengths, deposition, and accumulation. However, greater possibilities for the application of MLH data have been identified in recent years. Here, the results of measurements in Berlin in 2014 are shown and discussed. The concentrations of NO, NO2, O3, CO, PM1, PM2.5, PM10 and about 70 volatile organic compounds (anthropogenic and biogenic of origin) as well as particle size distributions and contributions of SOA and soot species to PM were measured at the urban background station of the Berlin air quality network (BLUME) in Nansenstr./Framstr., Berlin-Neukölln. A Vaisala ceilometer CL51, which is a commercial mini-lidar system, was applied at that site to detect the layers of the lower atmosphere in real time. Special software for these ceilometers with MATLAB provided routine retrievals of MLH from vertical profiles of laser backscatter data. Five portable Bruker EM27/SUN FTIR spectrometers were set up around Berlin to detect column averaged abundances of CO2 and CH4 by solar absorption spectrometry. Correlation analyses were used to show the coupling of temporal variations of trace gas compounds and PM with MLH. Significant influences of MLH upon NO, NO2, PM10, PM2.5, PM1 and toluene (marker for traffic emissions) concentrations as well as particle number concentrations in the size modes 70 - 100 nm, 100 - 200 nm and 200 - 500 nm on the basis of averaged diurnal courses were found. Further, MLH was taken as important auxiliary information about the development of the boundary layer during each day of observations, which was required for the proper estimation of CO2 and CH4 source strengths from Berlin on the basis of atmospheric column density measurements.

  6. Nuclear Physics in the SciDAC Era

    SciTech Connect

    Robert Edwards

    2009-08-01

    Lattice QCD currently provides our only means of solving QCD (Quantum Chromo Dynamics) -- the theory of the strong nuclear force -- in the low-energy regime, and thus of crucial importance for theoretical and experimental research programs in High Energy and Nuclear Physics. Under the SciDAC program, a software infrastructure has been developed for lattice QCD that effectively utilize the capabilities of the INCITE facilities. These developments have enabled a new generation of Nuclear Physics calculations investigating the spectrum and structure of matter, such as the origin of mass and spin. This software infrastructure is described and recent results are reviewed.

  7. The DAC system and associations with multiple myeloma.

    PubMed

    Ocio, Enrique M; San Miguel, Jesús F

    2010-12-01

    Despite the clear progress achieved in recent years in the treatment of MM, most patients eventually relapse and therefore novel therapeutic options are still necessary for these patients. In this regard, several drugs that target specific mechanisms of the tumor cells are currently being explored in the preclinical and clinical setting. This manuscripts offers a review of the rationale and current status of the antimyeloma activity of one of the most relevant examples of these targeted drugs: deacetylase inhibitors (DACi). Several studies have demonstrated the prooncogenic activity of deacetylases (DACs) through the targeting not only of histones but also of non histone proteins relevant to tumor progression, such as p53, E2F family members, Bcl-6, Hsp90, HIF-1α or Nur77. This fact together with the DACs overexpression present in several tumors, has prompted the development of some DACi with potential antitumor effect. This situation is also evident in the case of MM as two mechanisms of DACi, the inhibition of the epigenetic inactivation of p53 and the blockade of the unfolded protein response, through the inhibition of the aggressome formation (by targeting DAC6) and the inactivation of the chaperone system (by acetylating HSP-90), provides the rationale for the exploration of the potential antimyeloma activity of these compounds. Several DACi with different chemical structure and different selectivity for targeting the DAC families have been tested in MM. Their preclinical activity in monotherapy has been quite exciting and has been described to be mediated by various mechanisms: the induction of apoptosis and cell cycle arrest mainly by the upregulation of p21; the interferece with the interaction between plasma cells and the microenvironment, by reducing the expression and signalling of several cytokines or by inhibiting angiogenesis. Finally they also have a role in protecting murine models from myeloma bone disease. Neverteless, the clinical activity in

  8. Air

    MedlinePlus

    ... do to protect yourself from dirty air . Indoor air pollution and outdoor air pollution Air can be polluted indoors and it can ... this chart to see what things cause indoor air pollution and what things cause outdoor air pollution! Indoor ...

  9. LINKING AIR TOXIC CONCENTRATIONS FROM CMAQ TO THE HAPEM5 EXPOSURE MODEL AT NEIGHORHOOD SCALES FOR THE PHILADELPHIA AREA

    EPA Science Inventory

    This paper provides a preliminary demonstration of the EPA neighborhood scale modeling paradigm for air toxics by linking concentration from the Community Multi-scale Air Quality (CMAQ) modeling system to the fifth version of the Hazardous Pollutant Exposure Model (HAPEM5). For ...

  10. Test of CAP88-PC's Predicted Concentrations of Tritium in Air at Lawrence Livermore National Laboratory

    SciTech Connect

    Peterson, S R

    2003-11-06

    Based on annual tritium release rates from the five sources of tritium at Lawrence Livermore National Laboratory and the Tritium Research Laboratory at Sandia National Laboratory, the regulatory dispersion and dose model, CAP88-PC, was used to predict tritium concentrations in air at perimeter and offsite air surveillance monitoring locations for 1986 through 2001. These predictions were compared with mean annual measured concentrations, based on biweekly sampling. Deterministic predictions were compared with deterministic observations using predicted-to-observed ratios. In addition, the uncertainty on observations and predictions was assessed: when the uncertainty bounds of the observations overlapped with the uncertainty bounds of the predictions, the predictions were assumed to agree with the observations with high probability. Deterministically, 54% of all predictions were higher than the observations, and 96% fell within a factor of three. Accounting for uncertainty, 75% of all predictions agreed with the observations; 87% of the predictions either matched or exceeded the observations. Predictions equaled or exceeded observations at those sampling locations towards which the wind blows most frequently, except those in the hills. Under-predictions were seen at locations towards which the wind blows infrequently when released tritium was from elevated sources. When a high fraction of tritium was from area (diffuse) sources, predictions matched observations.

  11. Vertical profile of tritium concentration in air during a chronic atmospheric HT release.

    PubMed

    Noguchi, Hiroshi; Yokoyama, Sumi

    2003-03-01

    The vertical profiles of tritium gas and tritiated water concentrations in air, which would have an influence on the assessment of tritium doses as well as on the environmental monitoring of tritium, were measured in a chronic tritium gas release experiment performed in Canada in 1994. While both of the profiles were rather uniform during the day because of atmospheric mixing, large gradients of the profiles were observed at night. The gradient coefficients of the profiles were derived from the measurements. Correlations were analyzed between the gradient coefficients and meteorological conditions: solar radiation, wind speed, and turbulent diffusivity. It was found that the solar radiation was highly correlated with the gradient coefficients of tritium gas and tritiated water profiles and that the wind speed and turbulent diffusivity showed weaker correlations with those of tritiated water profiles. A one-dimensional tritium transport model was developed to analyze the vertical diffusion of tritiated water re-emitted from the ground into the atmosphere. The model consists of processes of tritium gas deposition to soil including oxidation into tritiated water, reemission of tritiated water, dilution of tritiated water in soil by rain, and vertical diffusion of tritiated water in the atmosphere. The model accurately represents the accumulation of tritiated water in soil water and the time variations and vertical profiles of tritiated water concentrations in air.

  12. Portable Cathode-Air Vapor-Feed Electrochemical Medical Oxygen Concentrator (OC)

    NASA Technical Reports Server (NTRS)

    Balasubramanian, Ashwin

    2015-01-01

    Missions on the International Space Station and future space exploration will present significant challenges to crew health care capabilities, particularly in the efficient utilization of onboard oxygen resources. Exploration vehicles will require lightweight, compact, and portable oxygen concentrators that can provide medical-grade oxygen from the ambient cabin air. Current pressure-swing adsorption OCs are heavy and bulky, require significant start-up periods, operate in narrow temperature ranges, and require a liquid water feed. Lynntech, Inc., has developed an electrochemical OC that operates with a cathode-air vapor feed, eliminating the need for a bulky onboard water supply. Lynntech's OC is smaller and lighter than conventional pressure-swing OCs, is capable of instant start-up, and operates over a temperature range of 5-80 C. Accomplished through a unique nanocomposite proton exchange membrane and catalyst technology, the unit delivers 4 standard liters per minute of humidified oxygen at 60 percent concentration. The technology enables both ambient-pressure operating devices for portable applications and pressurized (up to 3,600 psi) OC devices for stationary applications.

  13. Influence of eutrophication on air-water exchange, vertical fluxes, and phytoplankton concentrations of persistent organic pollutants

    SciTech Connect

    Dachs, J.; Eisenreich, S.J.; Hoff, R.M.

    2000-03-15

    The influence of eutrophication on the biogeochemical cycles of persistent organic pollutants (POPs) such as polychlorinated biphenyls (PCBs) is largely unknown. In this paper, the application of a dynamic air-water-phytoplankton exchange model to Lake Ontario is used as a framework to study the influence of eutrophication on air-water exchange, vertical fluxes, and phytoplankton concentrations of POPs. The results of these simulations demonstrate that air-water exchange controls phytoplankton concentrations in remote aquatic environments with little influence from land-based sources of pollutants and supports levels in even historically contaminated systems. Furthermore, eutrophication or high biomass leads to a disequilibrium between the gas and dissolved phase, enhanced air-water exchange, and vertical sinking fluxes of PCBs. Increasing biomass also depletes the water concentrations leading to lower than equilibrium PCB concentrations in phytoplankton. Implications to future trends in PCB pollution in Lake Ontario are also discussed.

  14. Estimating PM 10 air concentrations from dust storms in Iraq, Kuwait and Saudi Arabia

    NASA Astrophysics Data System (ADS)

    Draxler, Roland R.; Gillette, Dale A.; Kirkpatrick, Jeffrey S.; Heller, Jack

    A model for the emission of PM 10 dust has been constructed using the concept of a threshold friction velocity which is dependent on surface roughness. Surface roughness in turn was correlated with geomorphology or soil properties for Kuwait, Iraq, part of Syria, Saudi Arabia, the United Arab Emirates and Oman. The PM 10 emission algorithm was incorporated into a Lagrangian transport and dispersion model. PM 10 air concentrations were computed from August 1990 through August 1991. The model predicted about the right number of dust events over Kuwait (events occur 18% of the time). The model results agreed quantitatively with measurements at four locations in Saudi Arabia and one in Kuwait for one major dust event (>1000 μg/m 3). However, for smaller scale dust events (200-1000 μg/m 3), especially at the coastal sampling locations, the model substantially over-predicted the air concentrations. Part of the over-prediction was attributed to the entrainment of dust-free air by the sea breeze, a flow feature not represented by the large-scale gridded meteorological data fields used in the model computation. Another part of the over-prediction was the model's strong sensitivity to threshold friction velocity and the surface soil texture coefficient (the soil emission factor), and the difficulty in accurately representing these parameters in the model. A comparison of the model predicted PM 10 spatial pattern with the TOMS satellite aerosol index (AI) yielded a spatial pattern covering a major portion of Saudi Arabia that was quite similar to the observed AI pattern.

  15. Influence of nitromethane concentration on ignition energy and explosion parameters in gaseous nitromethane/air mixtures.

    PubMed

    Zhang, Qi; Li, Wei; Lin, Da-Chao; He, Ning; Duan, Yun

    2011-01-30

    The aim of this paper is to provide new experimental data of the minimum ignition energy (MIE) of gaseous nitromethane/air mixtures to discuss the explosion pressure and the flame temperature as a function of nitromethane concentration. Observations on the influence of nitromethane concentration on combustion pressure and temperature through the pressure and temperature measure system show that peak temperature (the peak of combustion temperature wave) is always behind peak pressure (the peak of the combustion pressure wave) in arrival time, the peak combustion pressure of nitromethane increases in the range of its volume fraction 10-40% as the concentration of nitromethane increases, and it slightly decreases in the range of 40-50%. The maximum peak pressure is equal to 0.94 MPa and the minimum peak pressure 0.58 MPa. Somewhat similar to the peak pressure, the peak combustion temperature increases with the volume fraction of nitromethane in the range of 10-40%, and slightly decreases in 40-50%. The maximum peak temperature is 1340 °C and the minimum 860 °C. The combustion temperature rise rate increases with the concentration of nitromethane in 10-30%, while decreases in 30-50% and its maximum value of combustion temperature rise rate in 10-50% is 4200 °C/s at the volume fraction of 30%. Influence of the concentration of nitromethane on the combustion pressure rise rate is relatively complicated, and the maximum value of rise rate of combustion pressure wave in 10-50% is 11 MPa/s at the concentration 20%.

  16. The MTBE air concentrations in the cabin of automobiles while fueling.

    PubMed

    Vayghani, S A; Weisel, C

    1999-01-01

    Methyl tertiary-butyl ether (MTBE) is the most commonly used oxygenated compound added to gasoline to reduce ambient carbon monoxide levels. Complaints about perceived MTBE exposures and adverse health symptoms have been registered in several states, including New Jersey (NJ). Fueling automobiles is the activity thought to cause the highest environmental MTBE exposures. The current study was conducted to determine the MTBE concentrations inside automobile cabins during fueling, which represents the peak exposure that can occur at full service gasoline service stations, such as those that exist in NJ. Air samples were collected at service stations located on the NJ and PA turnpikes from March 1996 to July 1997 during which the MTBE content in gasoline varied. A bimodal distribution of MTBE concentrations was found in the cabin of the cars while fueling. The median MTBE, benzene and toluene in cabin concentrations were 100, 5.5 and 18 ppb, respectively, with the upper concentrations of the distribution exceeding 1 ppm for MTBE and 0.1 ppm for benzene and toluene. The highest in cabin concentrations occurred in a car that had a malfunctioning vapor recovery system and in a series of cars sampled on an unusually warm, calm winter day when the fuel volatility was high, the evaporation maximal and the dispersion by wind minimal. The in-cabin concentrations were typically higher when the car window was opened during the entire fueling process. Thus, exposure to MTBE during fueling can be reduced by properly maintaining the integrity of the fuel system and keeping the windows closed during fueling.

  17. Evaluating the impact of ambient benzene vapor concentrations on product water from Condensation Water From Air technology.

    PubMed

    Kinder, Katherine M; Gellasch, Christopher A; Dusenbury, James S; Timmes, Thomas C; Hughes, Thomas M

    2017-07-15

    Globally, drinking water resources are diminishing in both quantity and quality. This situation has renewed interest in Condensation Water From Air (CWFA) technology, which utilizes water vapor in the air to produce water for both potable and non-potable purposes. However, there are currently insufficient data available to determine the relationship between air contaminants and the rate at which they are transferred from the air into CWFA untreated product water. This study implemented a novel experimental method utilizing an environmental test chamber to evaluate how air quality and temperature affects CWFA untreated product water quality in order to collect data that will inform the type of water treatment required to protect human health. This study found that temperature and benzene air concentration affected the untreated product water from a CWFA system. Benzene vapor concentrations representing a polluted outdoor environment resulted in benzene product water concentrations between 15% and 23% of the USEPA drinking water limit of 5μg/l. In contrast, product water benzene concentrations representing an indoor industrial environment were between 1.4 and 2.4 times higher than the drinking water limit. Lower condenser coil temperatures were correlated with an increased concentration of benzene in the product water. Environmental health professionals and engineers can integrate the results of this assessment to predict benzene concentrations in the product water and take appropriate health protective measures.

  18. Analysis of radionuclide concentration in air released through the stack of a radiopharmaceutical production facility based on a medical cyclotron

    NASA Astrophysics Data System (ADS)

    Giardina, M.; Tomarchio, E.; Greco, D.

    2015-11-01

    Positron emitting radionuclides are increasingly used in medical diagnostics and the number of radiopharmaceutical production facilities have been estimated to be growing worldwide. During the process of production and/or patient administration of radiopharmaceuticals, an amount of these radionuclides might become airborne and escape into the environment. Therefore, the analysis of radionuclide concentration in the air released to the stack is a very important issue to evaluate the dose to the population living around the plant. To this end, sampling and measurement of radionuclide concentration in air released through the stack of a Nuclear Medicine Center (NMC), provided with a cyclotron for radiopharmaceuticals production, must be routinely carried out with an automatic measurement system. In this work is presented the air monitoring system realized at "San Gaetano" NMC at Bagheria (Italy) besides the analysis of the recorded stack relesead air concentration data. Sampling of air was carried out continuously and gamma-ray spectrometric measurement are made on-line and for a short time by using a shielded Marinelli beaker filled with sampled air and a gamma detector. The use of this system allows to have 1440 values of air concentration per day from 2002, year of the start of operation with the cyclotron. Therefore, the concentration values are very many and an analysis software is needed to determine the dose to the population. A comparison with the results of a simulation code based on a Gaussian Plume air dispersion modelling allow us to confirm the no-radiological significance of the stack effluent releases in terms of dose to population and to evaluate possible improvements in the plant devices to reduce the air concentration at stack.

  19. Diagnostic significance of nitric oxide concentrations in exhaled air from the airways in allergic rhinitis patients

    PubMed Central

    Krzych-Fałta, Edyta; Samoliński, Bolesław K; Zalewska, Marta

    2016-01-01

    Introduction The effect of nitric oxide (NO) on the human body is very important due its physiological regulation of the following functions of airways: modulation of ciliary movement and maintenance of sterility in sinuses. Aim To evaluate the diagnostic significance of NO concentrations in exhaled air from the upper and lower airways in patients diagnosed with allergic rhinitis (AR). Material and methods The subjects included in the study were a group of 30 people diagnosed with sensitivity to environmental allergens and a control group consisting of 30 healthy subjects. The measurement of NO in the air exhaled from the lower and upper airways was performed using an on-line method by means of Restricted Exhaled Breath (REB), as well as using the measurement procedure (chemiluminescence) set out in the guidelines prepared in 2005 by the American Thoracic Society and the European Respiratory Society. Results In the late phase of the allergic reaction, higher values of the level of exhaled NO concentration from the lower airways were observed in the groups of subjects up to the threshold values of 25.17 ppb in the group of subjects with year-round allergic rhinitis and 21.78 ppb in the group with diagnosed seasonal allergic rhinitis. The difference in the concentration of NO exhaled from the lungs between the test group and the control group in the 4th h of the test was statistically significant (p = 0.045). Conclusions Exhaled NO should be considered as a marker of airway inflammation. It plays an important role in the differential diagnosis of allergy. PMID:27279816

  20. Model-predicted concentrations of toxic air pollutants in the Minneapolis/St. Paul Metropolitan Area

    SciTech Connect

    McCourtney, M.; Pratt, G.; Wu, C.Y.

    1998-12-31

    The availability of sophisticated emission inventory methods, air dispersion models and personal computers has opened the door to developing more comprehensive studies of air concentrations of various pollutants. As part of a grant from the US Environmental Protection Agency, a current emission inventory and the Industrial Source Complex short-term dispersion model, version 3 (ISCST3) were used to estimate the ambient concentrations of several toxic compounds throughout the Minneapolis/St. Paul Metropolitan Area. A detailed emission inventory was developed of point, area and mobile sources in seven contiguous metropolitan counties that account for approximately half the population of Minnesota. Of specific interest were those sources that emit at least one of the eight Volatile Organic Compounds (VOCs): benzene, 1,3-butadiene, carbon tetrachloride, chloroform, methyl chloride, styrene, tetrachloroethylene and toluene. Emission rates were calculated for 69 industrial point sources; mobile sources, including on-road vehicles and non-road vehicles (such as aircraft, locomotives, commercial marine, agricultural, recreational, and lawn and garden equipment); and area sources, which consisted of dry cleaners, architectural surface coatings, commercial/consumer solvent products, residential fossil fuel combustion, automobile refinishing, residential wood burning, public-owned treatment works, landfills and gas stations. The ISCST3 model was used to estimate the 24-hour and annual average concentrations of the selected pollutants throughout the Minneapolis/St. Paul Metropolitan Area. Three sets of receptors were developed: a fine receptor grid with 500 meter spacing in the urban core, a coarse receptor grid with 5000 meter spacing covering the metropolitan area, and discrete receptors located 100 meters in each of four directions around each point source.

  1. Atmospheric concentrations of current-use pesticides across south-central Ontario using monthly-resolved passive air samplers

    NASA Astrophysics Data System (ADS)

    Gouin, T.; Shoeib, M.; Harner, T.

    In this study passive air samplers (PAS) were deployed on a monthly basis at a number of sites along a south-north transect, extending 700 km north from Toronto, Ontario, characterizing an urban-agricultural-forested gradient, to investigate the spatial and temporal trends of current-use pesticides (CUPs), between spring 2003 and spring 2004. The most frequently detected CUPs were chlorpyrifos, dacthal, trifluralin, and α-endosulfan. Highest air concentrations of chlorpyrifos were observed in May, whereas α-endosulfan and dacthal peaked in July and August, reflecting differences in usage patterns. At the agricultural site, representing the source region of CUPs, chlorpyrifos air concentrations (pg m -3) varied from 2700 to 3.2 and α-endulsulfan from 1600 to 19. The most frequently detected legacy pesticides were the hexachlorocylcohexanes (α-HCH and γ-HCH). For the forested sites, located on the Precambrian Shield, a region with limited agricultural activity, seasonal differences were less pronounced and air concentrations were observed to be much lower. For instance, air concentrations (pg m -3) of chlorpyrifos and α-endosulfan ranged from 7.6 to 0.3 and 50 to 2.0, respectively. By combining PAS data with trajectory air shed maps it is demonstrated that potential source-receptor relationships can be assessed. Air shed maps produced in this study indicate a potential of increased deposition of CUPs to Lake Erie and Lake Ontario.

  2. The concentration-response relation between air pollution and daily deaths.

    PubMed Central

    Schwartz, J; Ballester, F; Saez, M; Pérez-Hoyos, S; Bellido, J; Cambra, K; Arribas, F; Cañada, A; Pérez-Boillos, M J; Sunyer, J

    2001-01-01

    Studies on three continents have reported associations between various measures of airborne particles and daily deaths. Sulfur dioxide has also been associated with daily deaths, particularly in Europe. Questions remain about the shape of those associations, particularly whether there are thresholds at low levels. We examined the association of daily concentrations of black smoke and SO(2) with daily deaths in eight Spanish cities (Barcelona, Bilbao, Castellón, Gijón, Oviedo, Valencia, Vitoria, and Zaragoza) with different climates and different environmental and social characteristics. We used nonparametric smoothing to estimate the shape of the concentration-response curve in each city and combined those results using a metasmoothing technique developed by Schwartz and Zanobetti. We extended their method to incorporate random variance components. Black smoke had a nearly linear association with daily deaths, with no evidence of a threshold. A 10 microg/m(3) increase in black smoke was associated with a 0.88% increase in daily deaths (95% confidence interval, 0.56%-1.20%). SO(2) had a less plausible association: Daily deaths increased at very low concentrations, but leveled off and then decreased at higher concentrations. These findings held in both one- and two-pollutant models and held whether we optimized our weather and seasonal model in each city or used the same smoothing parameters in each city. We conclude that the association with particle levels is more convincing than for SO(2), and without a threshold. Linear models provide an adequate estimation of the effect of particulate air pollution on mortality at low to moderate concentrations. PMID:11675264

  3. Indirect determination of O-ethyl S-(2-diisopropylaminoethyl) methylphosphonothioate in air at low concentrations.

    PubMed

    Fowler, W K; Smith, J E

    1989-09-08

    This paper describes an indirect method for the quantification of the toxic military agent O-ethyl S-(2-diisopropylaminoethyl) methylphosphonothioate (VX) in the vapor state in air or other similar gases at ng/m3 levels. The method begins with the passage of a gaseous sample through a filter impregnated with silver fluoride to convert the VX vapor to ethyl methylphosphonofluoridate. The latter compound is then trapped on a bed of Chromosorb 106, transferred to a smaller bed of the same sorbent, and desorbed thermally into a gas chromatograph equipped with a flame-photometric detector. The method is comparable in sensitivity to the principal alternative method, which is based on cholinesterase inhibition, and it is less subject to interference from common organic solvents and other cholinesterase inhibitors. The detection limit was found to be limited by, and therefore dependent on, the nature and extent of any background substances that produced a significant chromatographic signal or response at the retention time of the analyte. In the absence of such substances, the instrument provided a response to 0.19 ng of VX that was thirty times larger than the peak-to-peak noise amplitude on the chromatographic base line. Moreover, the method bias (i.e., 100% minus the percent VX recovery) was found to depend on VX concentration, with estimates of agent recovery ranging from 83% at a VX concentration of 0.67 ng/m3 to 104% at a concentration of 0.084 ng/m3. The relative standard deviation varied with VX concentration and with the nature of the test that was performed to estimate it. It ranged from 2.1% in one VX vapor-challenge test to 17% in an experiment involving spiked sampling tubes, and it was generally lower at the higher VX test concentrations.

  4. Factors Affecting Indoor Air Concentrations of Volatile Organic Compounds at a Site of Subsurface Gasoline Contamination

    SciTech Connect

    Fischer, M.L.; Bentley, A.J.; Dunkin, K.A.; Hodgson, A.T.; Nazaroff, W.W.; Sextro, R.G.; Daisey, J.M.

    1995-11-01

    We report a field study of soil gas transport of volatile organic compounds (VOCs) into a slab-on-grade building found at a site contaminated with gasoline. Although the high VOC concentrations (30-60 g m{sup -3}) measured in the soil gas at depths of 0.7 m below the building suggest a potential for high levels of indoor VOC, the measured indoor air concentrations were lower than those in the soil gas by approximately six orders of magnitude ({approx} 0.03 mg m{sup -3}). This large ratio is explained by (1) the expected dilution of soil gas entering the building via ambient building ventilation (a factor of {approx}1000), and (2) an unexpectedly sharp gradient in soil gas VOC concentration between the depths of 0.1 and 0.7 m (a factor of {approx}1000). Measurements of the soil physical and biological characteristics indicate that a partial physical barrier to vertical transport in combination with microbial degradation provides a likely explanation for this gradient. These factors are likely to be important to varying degrees at other sites.

  5. Analysis of indoor concentrations of benzene using an air-quality model.

    PubMed

    Bouhamra, W S; Elkilani, A S; Raheem, M Y

    2000-01-01

    We performed measurements to determine indoor benzene levels in 26 residential houses in Kuwait, located in zones of different activity levels. Pumped (or active) sampling was conducted via use of 12 sampling tubes over a period of 24 hr for both indoor and outdoor concentrations simultaneously. Time-average indoor concentration varied linearly with time-average outdoor concentration in accordance with a mass-balance-based indoor air-quality model in which source and sink terms were incorporated. We used regression analysis to determine benzene adsorption rates, which appear in the removal and source terms of the model. The removal rate parameter varied between 0.12/hr and 2.16/hr, whereas source term parameter varied between 0.60 mg/hr and 76.07 mg/hr. Houses were then divided into three groups according to their benzene source strengths (i.e., < 1.0 mg/hr, 1-10 mg/hr, and 10-50 mg/hr). Qualitatively, these levels depended on the characteristics of occupants (e.g., smoking and gas cooker use, number of cars, and parking area) and location of the building.

  6. Effect of plateout, air motion and dust removal on radon decay product concentration in a simulated residence.

    PubMed

    Rudnick, S N; Hinds, W C; Maher, E F; First, M W

    1983-08-01

    The effectiveness of increased air motion and dust removal in reducing radon decay product concentration in residences subject to radon intrusion was evaluated in a 78-m3 room under steady-state conditions for air infiltration rates between 0.2 and 0.9 air changes per hour. Room-size, portable electrostatic precipitators and high-efficiency fibrous filters were tested as typical residential air cleaning devices; a portable box fan and a ceiling fan were employed as typical residential air movers. Reductions in working levels of 40-90% were found. The fate of radon decay products, with and without mixing fans, was determined by direct measurement. When mixing fans were used, most of the nonairborne potential alpha-energy was plated out on the room surfaces; less than 10% was deposited on the fan blades or housing. Results were compared to a mathematical model based on well-mixed room air, and good agreement was obtained.

  7. Effects of trans-Eurasian transport of air pollutants on surface ozone concentrations over Western China

    NASA Astrophysics Data System (ADS)

    Li, Xiaoyuan; Liu, Junfeng; Mauzerall, Denise L.; Emmons, Louisa K.; Walters, Stacy; Horowitz, Larry W.; Tao, Shu

    2014-11-01

    Due to a lack of industrialization in Western China, surface air there was, until recently, believed to be relatively unpolluted. However, recent measurements and modeling studies have found high levels of ozone (O3) there. Based on the state-of-the-science global chemical transport model MOZART-4, we identify the origin, pathway, and mechanism of trans-Eurasian transport of air pollutants to Western China in 2000. MOZART-4 generally simulates well the observed surface O3 over inland areas of China. Simulations find surface ozone concentrations over Western China on average to be about 10 ppbv higher than Eastern China. Using sensitivity studies, we find that anthropogenic emissions from all Eurasian regions except China contribute 10-15 ppbv surface O3 over Western China, superimposed upon a 35-40 ppbv natural background. Transport from European anthropogenic sources to Northwestern China results in 2-6 ppbv O3 enhancements in spring and summer. Indian anthropogenic sources strongly influence O3 over the Tibetan Plateau during the summer monsoon. Transport of O3 originating from emissions in the Middle East occasionally reach Western China and increase surface ozone there by about 1-4 ppbv. These influences are of similar magnitude as trans-Pacific and transatlantic transport of O3 and its precursors, indicating the significance of trans-Eurasian ozone transport in hemispheric transport of air pollution. Our study further indicates that mitigation of anthropogenic emissions from Europe, the Indian subcontinent, and the Middle East could benefit public health and agricultural productivity in Western China.

  8. Concentrations of 20 volatile organic compounds in the air and drinking water of 350 residents of New Jersey compared with concentrations in their exhaled breath

    SciTech Connect

    Wallace, L.; Pellizzari, E.; Hartwell, T.; Zelon, H.; Sparacino, C.; Perritt, R.; Whitmore, R.

    1986-08-01

    Twenty volatile organic compounds were measured in the personal air and drinking water of 350 New Jersey residents in the fall of 1981. Two consecutive 12-hour integrated personal air samples and two tap water samples were collected from each participant. At the end of the 24-hour monitoring period, each participant supplied a sample of exhaled breath. Simultaneous outdoor samples were collected in 100 residential locations in two cities. Eleven compounds were present much of the time in air, but only four (the trihalomethanes) in water; wide ranges of exposures (three to four orders of magnitude) were noted for most compounds. Ten of 11 compounds displayed significant correlations between air exposures and breath concentrations; the 11th (chloroform) was correlated with drinking water exposures. It was concluded that breath measurements are a feasible, cost-effective, and highly sensitive way to determine environmental and occupational exposures to volatile organic compounds.

  9. Concentrations of 20 volatile organic compounds in the air and drinking water of 350 residents of New Jersey compared with concentrations in their exhaled breath.

    PubMed

    Wallace, L; Pellizzari, E; Hartwell, T; Zelon, H; Sparacino, C; Perritt, R; Whitmore, R

    1986-08-01

    Twenty volatile organic compounds were measured in the personal air and drinking water of 350 New Jersey residents in the fall of 1981. Two consecutive 12-hour integrated personal air samples and two tap water samples were collected from each participant. At the end of the 24-hour monitoring period, each participant supplied a sample of exhaled breath. Simultaneous outdoor samples were collected in 100 residential locations in two cities. Eleven compounds were present much of the time in air, but only four (the trihalomethanes) in water; wide ranges of exposures (three to four orders of magnitude) were noted for most compounds. Ten of 11 compounds displayed significant correlations between air exposures and breath concentrations; the 11th (chloroform) was correlated with drinking water exposures. It was concluded that breath measurements are a feasible, cost-effective, and highly sensitive way to determine environmental and occupational exposures to volatile organic compounds.

  10. [Confrontation of knowledge on alcohol concentration in blood and in exhaled air].

    PubMed

    Bauer, Miroslav; Bauerová, Jiřina; Šikuta, Ján; Šidlo, Jozef

    2015-01-01

    The authors of the paper give a brief historical overview of the development of experimental alcohology in the former Czechoslovakia. Enhanced attention is paid to tests of work quality control of toxicological laboratories. Information on results of control tests of blood samples using the method of gas chromatography in Slovakia and within a world-wide study "Eurotox 1990" is presented. There are pointed out the pitfalls related to objective evaluation of the analysis results interpreting alcohol concentration in biological materials and the associated need to eliminate a negative influence of the human factor. The authors recommend performing analyses of alcohol in biological materials only at accredited workplaces and in the case of samples storage to secure a mandatory inhibition of phosphorylation process. There are analysed the reasons of numerical differences of analyses while taking evidence of alcohol in blood and in exhaled air. The authors confirm analysis accuracy using the method of gas chromatography along with breath analysers of exhaled air. They highlight the need for making the analysis results more objective also through confrontation with the results of clinical examination and with examined circumstances. The authors suggest a method of elimination of the human factor, the most frequently responsible for inaccuracy, to a tolerable level (safety factor) and the need of sample analysis by two methods independent of each other or the need of analysis of two biological materials.

  11. A critical review of reported air concentrations of organic compounds in aircraft cabins.

    PubMed

    Nagda, N L; Rector, H E

    2003-09-01

    This paper presents a review and assessment of aircraft cabin air quality studies with measured levels of volatile and semivolatile organic compounds (VOCs and SVOCs). VOC and SVOC concentrations reported for aircraft cabins are compared with those reported for residential and office buildings and for passenger compartments of other types of transportation. An assessment of measurement technologies and quality assurance procedures is included. The six studies reviewed in the paper range in coverage from two to about 30 flights per study. None of the monitored flights included any unusual or episodic events that could affect cabin air quality. Most studies have used scientifically sound methods for measurements. Study results indicate that under routine aircraft operations, contaminant levels in aircraft cabins are similar to those in residential and office buildings, with two exceptions: (1). levels of ethanol and acetone, indicators of bioeffluents and chemicals from consumer products are higher in aircraft than in home or office environments, and (2). levels of certain chlorinated hydrocarbons and fuel-related contaminants are higher in residential/office buildings than in aircraft. Similarly, ethanol and acetone levels are higher in aircraft than in other transportation modes but the levels of some pollutants, such as m-/p-xylenes, tend to be lower in aircraft.

  12. Validation of minicams for measuring concentrations of chemical agent in environmental air

    SciTech Connect

    Menton, R.G.; Hayes, T.L.; Chou, Y.L.; Hobson, D.W.

    1993-05-13

    Environmental monitoring for chemical agents is necessary to ensure that notification and appropriate action will be taken in the, event that there is a release exceeding control limits of such agents into the workplace outside of engineering controls. Prior to implementing new analytical procedures for environmental monitoring, precision and accuracy (PA) tests are conducted to ensure that an agent monitoring system performs according to specified accuracy, precision, and sensitivity requirements. This testing not only establishes the accuracy and precision of the method, but also determines what factors can affect the method's performance. Performance measures that are particularly important in agent monitoring include the Detection Limit (DL), Decision Limit (DC), Found Action Level (FAL), and the Target Action Level (TAL). PA experiments were performed at Battelle's Medical Research and Evaluation Facility (MREF) to validate the use of the miniature chemical agent monitoring system (MINICAMs) for measuring environmental air concentrations of sulfur mustard (HD). This presentation discusses the experimental and statistical approaches for characterizing the performance of MINICAMS for measuring HD in air.

  13. EXTRAN: A computer code for estimating concentrations of toxic substances at control room air intakes

    SciTech Connect

    Ramsdell, J.V.

    1991-03-01

    This report presents the NRC staff with a tool for assessing the potential effects of accidental releases of radioactive materials and toxic substances on habitability of nuclear facility control rooms. The tool is a computer code that estimates concentrations at nuclear facility control room air intakes given information about the release and the environmental conditions. The name of the computer code is EXTRAN. EXTRAN combines procedures for estimating the amount of airborne material, a Gaussian puff dispersion model, and the most recent algorithms for estimating diffusion coefficients in building wakes. It is a modular computer code, written in FORTRAN-77, that runs on personal computers. It uses a math coprocessor, if present, but does not require one. Code output may be directed to a printer or disk files. 25 refs., 8 figs., 4 tabs.

  14. Measurements of soot, OH, and PAH concentrations in turbulent ethylene/air jet flames

    SciTech Connect

    Lee, Seong-Young; Turns, Stephen R.; Santoro, Robert J.

    2009-12-15

    This paper presents results from an investigation of soot formation in turbulent, non-premixed, C{sub 2}H{sub 4}/air jet flames. Tests were conducted using a H{sub 2}-piloted burner with fuel issuing from a 2.18 mm i.d. tube into quiescent ambient air. A range of test conditions was studied using the initial jet velocity (16.2-94.1 m/s) as a parameter. Fuel-jet Reynolds numbers ranged from 4000 to 23,200. Planar laser-induced incandescence (LII) was employed to determine soot volume fractions, and laser-induced fluorescence (LIF) was used to measure relative hydroxyl radical (OH) concentrations and polycyclic aromatic hydrocarbons (PAHs) concentrations. Extensive information on the structure of the soot and OH fields was obtained from two-dimensional imaging experiments. Quantitative measurements were obtained by employing the LII and LIF techniques independently. Imaging results for soot, OH, and PAH show the existence of three soot formation/oxidation regions: a rapid soot growth region, in which OH and soot particles lie in distinctly different radial locations; a mixing-dominated region controlled by large-scale motion; and a soot-oxidation region in which the OH and soot fields overlap spatially, resulting in the rapid oxidation of soot particles. Detailed quantitative analyzes of soot volume fractions and OH and soot zone thicknesses were performed along with the temperature measurement using the N{sub 2}-CARS system. Measurements of OH and soot zone thicknesses show that the soot zone thickness increases linearly with axial distance in the soot formation region, whereas the OH zone thickness is nearly constant in this region. The OH zone thickness then rapidly increases with downstream distance and approximately doubles in the soot-oxidation region. Probability density functions also were obtained for soot volume fractions and OH concentrations. These probability density functions clearly define the spatial relationships among the OH, PAH concentrations, the

  15. Chemodiversity of a Scots pine stand and implications for terpene air concentrations

    NASA Astrophysics Data System (ADS)

    Bäck, J.; Aalto, J.; Henriksson, M.; Hakola, H.; He, Q.; Boy, M.

    2012-02-01

    Atmospheric chemistry in background areas is strongly influenced by natural vegetation. Coniferous forests are known to produce large quantities of volatile vapors, especially terpenes. These compounds are reactive in the atmosphere, and contribute to the formation and growth of atmospheric new particles. Our aim was to analyze the variability of mono- and sesquiterpene emissions between Scots pine trees, in order to clarify the potential errors caused by using emission data obtained from only a few trees in atmospheric chemistry models. We also aimed at testing if stand history and seed origin has an influence on the chemotypic diversity. The inherited, chemotypic variability in mono- and sesquiterpene emission was studied in a seemingly homogeneous 48 yr-old stand in Southern Finland, where two areas differing in their stand regeneration history could be distinguished. Sampling was conducted in August 2009. Terpene concentrations in the air had been measured at the same site for seven years prior to branch sampling for chemotypes. Two main compounds, α-pinene and Δ3-carene formed together 40-97% of the monoterpene proportions in both the branch emissions and in the air concentrations. The data showed a bimodal distribution in emission composition, in particular in Δ3-carene emission within the studied population. 10% of the trees emitted mainly α-pinene and no Δ3-carene at all, whereas 20% of the trees where characterized as high Δ3-carene emitters (Δ3-carene forming >80% of total emitted monoterpene spectrum). An intermediate group of trees emitted equal amounts of both α-pinene and Δ3-carene. The emission pattern of trees at the area established using seeding as the artificial regeneration method differed from the naturally regenerated or planted trees, being mainly high Δ3-carene emitters. Some differences were also seen in e.g. camphene and limonene emissions between chemotypes, but sesquiterpene emissions did not differ significantly between trees

  16. A modeling framework for characterizing near-road air pollutant concentration at community scales.

    PubMed

    Chang, Shih Ying; Vizuete, William; Valencia, Alejandro; Naess, Brian; Isakov, Vlad; Palma, Ted; Breen, Michael; Arunachalam, Saravanan

    2015-12-15

    In this study, we combine information from transportation network, traffic emissions, and dispersion model to develop a framework to inform exposure estimates for traffic-related air pollutants (TRAPs) with a high spatial resolution. A Research LINE source dispersion model (R-LINE) is used to model multiple TRAPs from roadways at Census-block level for two U.S. regions. We used a novel Space/Time Ordinary Kriging (STOK) approach that uses data from monitoring networks to provide urban background concentrations. To reduce the computational burden, we developed and applied the METeorologically-weighted Averaging for Risk and Exposure (METARE) approach with R-LINE, where a set of selected meteorological data and annual average daily traffic (AADT) are used to obtain annual averages. Compared with explicit modeling, using METARE reduces CPU-time by 88-fold (46.8h versus 32min), while still retaining accuracy of exposure estimates. We show two examples in the Piedmont region in North Carolina (~105,000 receptors) and Portland, Maine (~7000 receptors) to characterize near-road air quality. Concentrations for NOx, PM2.5, and benzene in Portland drop by over 40% within 200m away from the roadway. The concentration drop in North Carolina is less than that in Portland, as previously shown in an observation-based study, showing the robustness of our approach. Heavy-duty diesel vehicles (HDDV) contribute over 55% of NOx and PM2.5 near interstate highways, while light-duty gasoline vehicles (LDGV) contribute over 50% of benzene to urban areas where multiple roadways intersect. Normalized mean error (NME) between explicit modeling and METARE in Portland ranges from 12.6 to 14.5% and normalized mean bias (NMB) ranges from -12.9 to -11.2%. When considering a static emission rate (i.e. the emission does not have temporal variability), both NME and NMB improved (10.5% and -9.5%). Modeled concentrations in Detroit, Michigan at an array of near-road monitors are within a factor of 2

  17. Soil air CO2 concentration as an integrative parameter of soil structure

    NASA Astrophysics Data System (ADS)

    Ebeling, Corinna; Gaertig, Thorsten; Fründ, Heinz-Christian

    2015-04-01

    The assessment of soil structure is an important but difficult issue and normally takes place in the laboratory. Typical parameters are soil bulk density, porosity, water or air conductivity or gas diffusivity. All methods are time-consuming. The integrative parameter soil air CO2 concentration ([CO2]) can be used to assess soil structure in situ and in a short time. Several studies highlighted that independent of soil respiration, [CO2] in the soil air increases with decreasing soil aeration. Therefore, [CO2] is a useful indicator of soil aeration. Embedded in the German research project RÜWOLA, which focus on soil protection at forest sites, we investigated soil compaction and recovery of soil structure after harvesting. Therefore, we measured soil air CO2 concentrations continuously and in single measurements and compared the results with the measurements of bulk density, porosity and gas diffusivity. Two test areas were investigated: At test area 1 with high natural regeneration potential (clay content approx. 25 % and soil-pH between 5 and 7), solid-state CO2-sensors using NDIR technology were installed in the wheel track of different aged skidding tracks in 5 and 10 cm soil depths. At area 2 (acidic silty loam, soil-pH between 3.5 and 4), CO2-sensors and water-tension sensors (WatermarkR) were installed in 6 cm soil depth. The results show a low variance of [CO2] in the undisturbed soil with a long term mean from May to June 2014 between 0.2 and 0.5 % [CO2] in both areas. In the wheel tracks [CO2] was consistently higher. The long term mean [CO2] in the 8-year-old-wheel track in test area 1 is 5 times higher than in the reference soil and shows a high variation (mean=2.0 %). The 18-year-old wheel track shows a long-term mean of 1.2 % [CO2]. Furthermore, there were strong fluctuations of [CO2] in the wheel tracks corresponding to precipitation and humidity. Similar results were yielded with single measurements during the vegetation period using a portable

  18. Using long-term air monitoring of semi-volatile organic compounds to evaluate the uncertainty in polyurethane-disk passive sampler-derived air concentrations.

    PubMed

    Holt, Eva; Bohlin-Nizzetto, Pernilla; Borůvková, Jana; Harner, Tom; Kalina, Jiří; Melymuk, Lisa; Klánová, Jana

    2017-01-01

    Much effort has been made to standardise sampling procedures, laboratory analysis, data analysis, etc. for semi volatile organic contaminants (SVOCs). Yet there are some unresolved issues in regards to comparing measurements from one of the most commonly used passive samplers (PAS), the polyurethane foam (PUF) disk PAS (PUF-PAS), between monitoring networks or different studies. One such issue is that there is no universal means to derive a sampling rate (Rs) or to calculate air concentrations (Cair) from PUF-PAS measurements for SVOCs. Cair was calculated from PUF-PAS measurements from a long-term monitoring program at a site in central Europe applying current understanding of passive sampling theory coupled with a consideration for the sampling of particle associated compounds. Cair were assessed against concurrent active air sampler (AAS) measurements. Use of "site-based/sampler-specific" variables: Rs, calculated using a site calibration, provided similar results for most gas-phase SVOCs to air concentrations derived using "default" values (commonly accepted Rs). Individual monthly PUF-PAS-derived air concentrations for the majority of the target compounds were significantly different (Wilcoxon signed-rank (WSR) test; p < 0.05) to AAS regardless of the input values (site/sampler based or default) used to calculate them. However, annual average PUF-PAS-derived air concentrations were within the same order of magnitude as AAS measurements except for the particle-phase polycyclic aromatic hydrocarbons (PAHs). Underestimation of PUF-derived air concentrations for particle-phase PAHs was attributed to a potential overestimation of the particle infiltration into the PUF-PAS chamber and underestimation of the particle bound fraction of PAHs.

  19. Aerosol-Radiation Feedback and PM10 Air Concentrations Over Poland

    NASA Astrophysics Data System (ADS)

    Werner, Małgorzata; Kryza, Maciej; Skjøth, Carsten Ambelas; Wałaszek, Kinga; Dore, Anthony J.; Ojrzyńska, Hanna; Kapłon, Jan

    2017-02-01

    We have implemented the WRF-Chem model version 3.5 over Poland to quantify the direct and indirect feedback effects of aerosols on simulated meteorology and aerosol concentrations. Observations were compared with results from three simulations at high spatial resolutions of 5 × 5 km: (1) BASE—without any aerosol feedback effects; (2) DIR—with direct aerosol-radiative effects (3) INDIR—with direct and indirect aerosol-radiative effects. We study the overall effect during January 2011 as well as selected episodes of the highest differences in PM10 concentrations between the three simulations. For the DIR simulation, the decrease in monthly mean incoming solar radiation (SWDOWN) appears for the entire study area. It changes geographically, from about -8.0 to -2.0 W m-2, respectively for the southern and northern parts of the country. The highest changes do not correspond to the highest PM10 concentration. Due to the solar radiation changes, the surface mean monthly temperature (T2) decreases for 96 % of the area of Poland, but not more than 1.0 °C. Monthly mean PBLH changes by more than ±5 m for 53 % of the domain. Locally the differences in PBLH between the DIR and BASE are higher than ± 20 m. Due to the direct effect, for 84 % of the domain, the mean monthly PM10 concentrations increase by up to 1.9 µg m-3. For the INDIR simulation the spatial distribution of changes in incoming solar radiation as well as air temperature is similar to the DIR simulation. The decrease of SWDOWN is noticed for the entire domain and for 23 % of the domain is higher than -5.0 W m-2. The absolute differences of PBLH are slightly higher for INDIR than DIR but similarly distributed spatially. For daily episodes, the differences between the simulations are higher, both for meteorology and PM10 concentrations, and the pattern of changes is usually more complex. The results indicate the potential importance of the aerosol feedback effects on modelled meteorology and PM10

  20. Air flow and concentration fields at urban road intersections for improved understanding of personal exposure.

    PubMed

    Tiwary, Abhishek; Robins, Alan; Namdeo, Anil; Bell, Margaret

    2011-07-01

    This paper reviews the state of knowledge on modelling air flow and concentration fields at road intersections. The first part covers the available literature from the past two decades on experimental (both field and wind tunnel) and modelling activities in order to provide insight into the physical basis of flow behaviour at a typical cross-street intersection. This is followed by a review of associated investigations of the impact of traffic-generated localised turbulence on the concentration fields due to emissions from vehicles. There is a discussion on the role of adequate characterisation of vehicle-induced turbulence in making predictions using hybrid models, combining the merits of conventional approaches with information obtained from more detailed modelling. This concludes that, despite advancements in computational techniques, there are crucial knowledge gaps affecting the parameterisations used in current models for individual exposure. This is specifically relevant to the growing impetus on walking and cycling activities on urban roads in the context of current drives for sustainable transport and healthy living. Due to inherently longer travel times involved during such trips, compared to automotive transport, pedestrians and cyclists are subjected to higher levels of exposure to emissions. Current modelling tools seem to under-predict this exposure because of limitations in their design and in the empirical parameters employed.

  1. Low pCO2 Air-Polarized CO2 Concentrator Development

    NASA Technical Reports Server (NTRS)

    Schubert, Franz H.

    1997-01-01

    Life Systems completed a Ground-based Space Station Experiment Development Study Program which verifies through testing the performance and applicability of the electrochemical Air-Polarized Carbon Dioxide Concentrator (APC) process technology for space missions requiring low (i.e., less than 3 mm Hg) CO2 partial pressure (pCO2) in the cabin atmosphere. Required test hardware was developed and testing was accomplished at an approximate one-person capacity CO2 removal level. Initially, two five-cell electrochemical modules using flight-like 0.5 sq ft cell hardware were tested individually, following by their testing at the integrated APC system level. Testing verified previously projected performance and established a database for sizing of APC systems. A four person capacity APC system was sized and compared with four candidate CO2 removal systems. At its weight of 252 lb, a volume of 7 cu ft and a power consumption of 566 W while operating at 2.2 mm Hg pCO2, the APC was surpassed only by an Electrochemical Depolarized CO2 Concentrator (EDC) (operating with H2), when compared on a total equivalent basis.

  2. Synergy of 5-aza-2'-deoxycytidine (DAC) and paclitaxel in both androgen-dependent and -independent prostate cancer cell lines.

    PubMed

    Shang, Donghao; Liu, Yuting; Liu, Qingjun; Zhang, Fengbo; Feng, Lang; Lv, Wencheng; Tian, Ye

    2009-06-08

    To determine the synergy of 5-aza-2'-deoxycytidine (DAC) and paclitaxel (PTX) against prostate carcinoma (PC) cells by isobolographic analysis. We demonstrated that DAC could significantly increase the susceptibility of PC cells to PTX, and confirmed the synergy of DAC and PTX. DAC enhanced the PTX induced up-regulation of caspase activity and antiproliferative effect, resulting in an increase of cells in subG1 and G2/M phases. In addition, the synergy was observed in both androgen-dependent and -independent PC cell lines. It suggested that combination chemotherapy with DAC and PTX might be a new strategy to improve the clinical response rate of PC.

  3. The vegetation-to-air concentration ratio in a specific activity atmospheric tritium model

    SciTech Connect

    Hamby, D.M.; Bauer, L.R.

    1994-03-01

    Specific activity models are frequently used to estimate the concentration of tritium oxide in vegetation. In such models, a single value represents the ratio (R) of the specific activity of tritium oxide in vegetation to the specific activity of atmospheric tritium oxide. Federal agencies such as the Nuclear Regulatory Commission and the Environmental Protection Agency have not established a consensus default for R. Literature on this topic suggests that a site-specific distribution of R should be developed when feasible. In this study, a distribution of R is established for the Savannah River Site. Environmental tritium concentrations in air and vegetation measured on and around the Savannah River Site over a 9-y period form the basis for the analysis. For dose assessments of chronic atmospheric tritium releases at the Savannah River Site, R is best parameterized by a normal distribution with a mean of 0.54 and one standard deviation of 0.10. The Nuclear Regulatory Commission default for R is approximately equal to the Savannah River Site site-specific estimate. Based on the results, the default value for R recognized by the Environmental Protection Agency overestimates tritium concentrations in vegetation and, therefore, doses from foodstuff consumption pathways at humid sites. For the Savannah River Site, the magnitude of the error is on the order of a factor of 2. This consideration may be important if an estimated dose approaches an as-low-as-reasonably-achievable or regulatory threshold. Conversely, without the benefit of site-specific data, ingestion doses may be underestimated in regions with dry climates. 11 refs., 1 fig., 3 tabs.

  4. The vegetation-to-air concentration ratio in a specific activity atmospheric tritium model.

    PubMed

    Hamby, D M; Bauer, L R

    1994-03-01

    Specific activity models are frequently used to estimate the concentration of tritium oxide in vegetation. In such models, a single value represents the ratio (R) of the specific activity of tritium oxide in vegetation to the specific activity of atmospheric tritium oxide. Federal agencies such as the Nuclear Regulatory Commission and the Environmental Protection Agency have not established a consensus default for R. Literature on this topic suggests that a site-specific distribution of R should be developed when feasible. In this study, a distribution of R is established for the Savannah River Site. Environmental tritium concentrations in air and vegetation measured on and around the Savannah River Site over a 9-y period form the basis for the analysis. For dose assessments of chronic atmospheric tritium releases at the Savannah River Site, R is best parameterized by a normal distribution with a mean of 0.54 and one standard deviation of 0.10. The Nuclear Regulatory Commission default for R is approximately equal to the Savannah River Site site-specific estimate. Based on the results, the default value for R recognized by the Environmental Protection Agency overestimates tritium concentrations in vegetation and, therefore, doses from foodstuff consumption pathways at humid sites. For the Savannah River Site, the magnitude of the error is on the order of a factor of 2. This consideration may be important if an estimated dose approaches an as-low-as-reasonably-achievable or regulatory threshold. Conversely, without the benefit of site-specific data, ingestion doses may be underestimated in regions with dry climates.

  5. Trends in mercury wet deposition and mercury air concentrations across the U.S. and Canada

    USGS Publications Warehouse

    Weiss-Penzias, Peter S.; Gay, David A.; Brigham, Mark E.; Parsons, Matthew T.; Gustin, Mae S.; ter Shure, Arnout

    2016-01-01

    This study examined the spatial and temporal trends of mercury (Hg) in wet deposition and air concentrations in the United States (U.S.) and Canada between 1997 and 2013. Data were obtained from the National Atmospheric Deposition Program (NADP) and Environment Canada monitoring networks, and other sources. Of the 19 sites with data records from 1997–2013, 53% had significant negative trends in Hg concentration in wet deposition, while no sites had significant positive trends, which is in general agreement with earlier studies that considered NADP data up until about 2010. However, for the time period 2007–2013 (71 sites), 17% and 13% of the sites had significant positive and negative trends, respectively, and for the time period 2008–2013 (81 sites) 30% and 6% of the sites had significant positive and negative trends, respectively. Non-significant positive tendencies were also widespread. Regional trend analyses revealed significant positive trends in Hg concentration in the Rocky Mountains, Plains, and Upper Midwest regions for the recent time periods in addition to significant positive trends in Hg deposition for the continent as a whole. Sulfate concentration trends in wet deposition were negative in all regions, suggesting a lower importance of local Hg sources. The trend in gaseous elemental Hg from short-term datasets merged as one continuous record was broadly consistent with trends in Hg concentration in wet deposition, with the early time period (1998–2007) producing a significantly negative trend (− 1.5 ± 0.2% year− 1) and the recent time period (2008–2013) displaying a flat slope (− 0.3 ± 0.1% year− 1, not significant). The observed shift to more positive or less negative trends in Hg wet deposition primarily seen in the Central-Western regions is consistent with the effects of rising Hg emissions from regions outside the U.S. and Canada and the influence of long-range transport in the free troposphere.

  6. Reduced-Rank Spatio-Temporal Modeling of Air Pollution Concentrations in the Multi-Ethnic Study of Atherosclerosis and Air Pollution1

    PubMed Central

    Olives, Casey; Sheppard, Lianne; Lindström, Johan; Sampson, Paul D.; Kaufman, Joel D.; Szpiro, Adam A.

    2016-01-01

    There is growing evidence in the epidemiologic literature of the relationship between air pollution and adverse health outcomes. Prediction of individual air pollution exposure in the Environmental Protection Agency (EPA) funded Multi-Ethnic Study of Atheroscelerosis and Air Pollution (MESA Air) study relies on a flexible spatio-temporal prediction model that integrates land-use regression with kriging to account for spatial dependence in pollutant concentrations. Temporal variability is captured using temporal trends estimated via modified singular value decomposition and temporally varying spatial residuals. This model utilizes monitoring data from existing regulatory networks and supplementary MESA Air monitoring data to predict concentrations for individual cohort members. In general, spatio-temporal models are limited in their efficacy for large data sets due to computational intractability. We develop reduced-rank versions of the MESA Air spatio-temporal model. To do so, we apply low-rank kriging to account for spatial variation in the mean process and discuss the limitations of this approach. As an alternative, we represent spatial variation using thin plate regression splines. We compare the performance of the outlined models using EPA and MESA Air monitoring data for predicting concentrations of oxides of nitrogen (NOx)—a pollutant of primary interest in MESA Air—in the Los Angeles metropolitan area via cross-validated R2. Our findings suggest that use of reduced-rank models can improve computational efficiency in certain cases. Low-rank kriging and thin plate regression splines were competitive across the formulations considered, although TPRS appeared to be more robust in some settings. PMID:27014398

  7. Concentration, temperature, and density in a hydrogen-air flame by excimer-induced Raman scattering

    NASA Technical Reports Server (NTRS)

    Wehrmeyer, Joseph A.; Bowling, John M.; Pitz, Robert W.

    1988-01-01

    Single-pulse, vibrational Raman scattering (VRS) is an attractive laser diagnostic for the study of supersonic hydrogen-air combustion. The VRS technique gives a complete thermodynamic description of the gas mixture at a point in the reacting flow. Single-pulse, vibrational Raman scattering can simultaneously provide independent measurements of density, temperature, and concentration of each major species (H2, H2O, O2 and N2) in a hydrogen/air turbulent combustor. Also the pressure can be calculated using the ideal gas law. However, single-pulse VRS systems in current use for measurement of turbulent combustion have a number of shortcomings when applied to supersonic flows: (1) slow repetition rate (1 to 5 Hz), (2) poor spatial resolution (0.5x0.3x0.3 cu mm), and (3) marginal time resolution. Most of these shortcomings are due to the use of visible wavelength flash-lamp pumped dye lasers. The advent of UV excimer laser allows the possibility of dramatic improvements in the single-pulse, vibrational Raman scattering. The excimer based VRS probe will greatly improve repetition rate (100 to 500 Hz), spatial resolution (0.1x0.1x0.1 cu mm) and time resolution (30ns). These improvements result from the lower divergence of the UV excimer, higher repetition rate, and the increased Raman cross-sections (15 to 20 times higher) at ultra-violet (UV) wavelengths. With this increased capability, single-pulse vibrational Raman scattering promises to be an ideal non-intrusive probe for the study of hypersonic propulsion flows.

  8. Influences of ambient air PM₂.₅ concentration and meteorological condition on the indoor PM₂.₅ concentrations in a residential apartment in Beijing using a new approach.

    PubMed

    Han, Yang; Qi, Meng; Chen, Yilin; Shen, Huizhong; Liu, Jing; Huang, Ye; Chen, Han; Liu, Wenxin; Wang, Xilong; Liu, Junfeng; Xing, Baoshan; Tao, Shu

    2015-10-01

    PM2.5 concentrations in a typical residential apartment in Beijing and immediately outside of the building were measured simultaneously during heating and non-heating periods. The objective was to quantitatively explore the relationship between indoor and outdoor PM2.5 concentrations. A statistical method for predicting indoor PM2.5 concentrations was proposed. Ambient PM2.5 concentrations were strongly affected by meteorological conditions, especially wind directions. A bimodal distribution was identified during the heating season due to the frequent and rapid transition between severe pollution events and clean days. Indoor PM2.5 concentrations were significantly correlated with outdoor PM2.5 concentrations but with 1-2 h delay, and the differences can be explained by ambient meteorological features, such as temperature, humidity, and wind direction. These results indicate the potential to incorporate indoor exposure features to the regional air quality model framework and to more accurately estimate the epidemiological relationship between human mortality and air pollution exposure.

  9. Minimum detectable activity concentration in direct alpha spectrometry from outdoor air samples: continuous monitoring versus separate sampling and counting.

    PubMed

    Pöllänen, R; Siiskonen, T

    2006-02-01

    Rapid method for identifying the presence of alpha particle emitting radionuclides in outdoor air is of paramount importance should a nuclear or radiological incident occur. Minimum detectable activity concentrations of U, U, Pu, and Pu in outdoor air are calculated for two direct alpha spectrometry methods: continuous air monitoring is compared with separate sampling and subsequent alpha particle counting in a vacuum chamber. The radon progeny activity concentration typical for outdoor air and the effects for the alpha particle spectra caused by the properties of the filter and the aerosol particles are taken into account using measurements and Monte Carlo simulations. Continuous air monitoring is a faster method for identifying the presence of (trans)uranium elements when their activity concentration is considerably higher than the typical detection limit. Separate sampling and counting in a vacuum chamber is a more sensitive method when concentrations are close to the detection limit and when the duration of the sampling-counting cycle is greater than approximately 2 h. The method may serve as a tool for rapid field measurements.

  10. Volatile methyl siloxanes (VMS) concentrations in outdoor air of several Catalan urban areas

    NASA Astrophysics Data System (ADS)

    Gallego, E.; Perales, J. F.; Roca, F. J.; Guardino, X.; Gadea, E.

    2017-04-01

    Volatile methyl siloxanes (VMS) were evaluated in ten Catalan urban areas with different industrial impacts, such as petrochemical industry, electrical and mechanical equipment, metallurgical and chemical industries, municipal solid waste treatment plant and cement and food industries, during 2013-2015. 24 h samples were taken with LCMA-UPC pump samplers specially designed in our laboratory, with a flow range of 70 ml min-1. A sorbent-based sampling method, successfully developed to collect a wide-range of VOC, was used. The analysis was performed by automatic thermal desorption coupled with capillary gas chromatography/mass spectrometry detector. The presented methodology allows the evaluation of VMS together with a wide range of other VOC, increasing the number of compounds that can be determined in outdoor air quality assessment of urban areas. This aspect is especially relevant as a restriction of several VMS (D4 and D5) in consumer products has been made by the European Chemicals Agency and US EPA is evaluating to include D4 in the Toxic Substances Control Act, regarding the concern of the possible effects of these compounds in human health and the environment. ΣVMS concentrations (L2-L5, D3-D6 and trimethylsilanol) varied between 0.3 ± 0.2 μg m-3 and 18 ± 12 μg m-3, determined in a hotspot area. Observed VMS concentrations were generally of the same order of magnitude than the previously determined in Barcelona, Chicago and Zurich urban areas, but higher than the published from suburban sites and Arctic locations. Cyclic siloxanes concentrations were up to two-three orders of magnitude higher than those of linear siloxanes, accounting for average contributions to the total concentrations of 97 ± 6% for all samples except for the hotspot area, where cyclic VMS accounted for 99.9 ± 0.1%. D5 was the most abundant siloxane in 5 sampling points; however, differing from the generally observed in previous studies, D3 was the most abundant compound in the

  11. Liquid products from oxidative thermal treatment of oil sludge with different oxygen concentrations of air.

    PubMed

    Shie, J L; Chang, C Y; Lin, J P; Le, D J; Wu, C H

    2001-01-01

    Oxidative thermal treatment of oil sludge with different oxygen concentrations of air by using a dynamic thermogravimetric (TG) reaction system is investigated. The experimental conditions employed are: gas flow rate of 50 cm3/min (value at 298 K) for 300 mg dry waste, a constant heating rate of 5.2 K/min, the oxygen concentrations in air of 1.09, 8.62 and 20.95 vol. % O2, and the temperature (T) range of 378-873 K. From the experimental results, the residual mass fractions (M) are about 78.95, 28.49, 8.77 and 4.13 wt. % at the oxidative T of 563, 713, 763 and 873 K for the case with 20.95 vol. % O2, respectively. The values of M with 8.62 and 1.09 vol. % O2 at T of 873 K are 4.87 and 9.44 wt. %, respectively. The distillation characteristics of the oil portion of liquid products (condensates of gas at 298 K) from the oxidative thermal treatment of oil sludge with 20.95 vol. % O2 at T of 378-873 K is close to those of commercial gasoline. Nevertheless, the liquid product contains a large amount of water. The distillation characteristics of the oil portions of liquid products with 8.62 and 1.09 vol. % O2 at T of 378-873 K are close to those of diesel and fuel oils, respectively. The oil quality with 8.62 vol. % O2 is better than that with 1.09 vol. % O2. However, the liquid product with 8.62 vol. % O2 still contains a large amount of water; nonetheless, that with 1.09 vol. % O2 is with negligible water. Compared with the oil product of nitrogen pyrolysis, the oil quality with 1.09 vol. % O2 is better. Certainly, low oxygen conditions (i.e. 1.09 vol. % O2) not only accelerate the thermal reaction of oil sludge, but also at the same time avoid or reduce the production of water. Further, from the analysis of benzene (B), ethylbenzene (E), toluene (T) and iso-xylene (X) concentrations of the oil portion of liquid products, the BETX concentrations of oil with 20.95 vol. % O2 are higher than those with 8.62 and 1.09 vol. % O2. The yields of liquid products with 20.95, 8

  12. Assessing the impact of the forthcoming decrease in diesel exhaust particulate matter emissions on air quality: implications for black carbon concentrations in ambient air

    NASA Astrophysics Data System (ADS)

    González, Y.; Rodríguez, S.; Cuevas, E.; Ramos, R.; Abreu-Afonso, J.; Baldasano, J. M.

    2009-04-01

    Forthcoming regulations (e.g. EURO 5 and EURO 6) are planned to reduce particulate matter emissions (PM) in the exhaust of forthcoming vehicles. In this study we assess the impact of such reduction in the diesel PM exhaust emissions on the urban ambient air PM concentrations. This has been done by studying the relationship between black carbon (BC) and carbon monoxide (CO) in urban ambient air and in the exhaust of current and forthcoming vehicles. The slope of the BC-vs-CO linear relationship is mainly affected by the percentage (%) of diesel automobiles in the urban vehicles fleet. This slope is a better indicator of the diesel PM emissions than bulk BC concentrations in urban ambient air. BC-vs-CO slopes within the range 1-3 and 7-14 ngBC/µgCO are typically observed in urban areas with low (<25%) and high (≥50%) proportions of diesel-fuel consumption for on road transportation, respectively. The entry into force of forthcoming regulations will decrease the BC-vs-CO slope in urban ambient air from about 10 to 5 ngBC/µgCO in the next decade, according to calculations based on the current data on diesel vehicles in urban fleets in Spanish cities. However, this will not necessary prompt a significant decrease in the urban BC concentrations if road traffic volume follows the increasing trend of the last decade. The results of this study shows that the analysis of the BC-vs-CO slope trend in ambient air is an useful tool for understanding the involvement "of the changes in the vehicle exhaust emissions rates" and "of the changes in the road traffic volume" in the BC and PMx trends in urban ambient air.

  13. Effect of the implosion and demolition of a hospital building on the concentration of fungi in the air.

    PubMed

    Barreiros, Gloria; Akiti, Tiyomi; Magalhães, Ana Cristina Gouveia; Nouér, Simone A; Nucci, Marcio

    2015-12-01

    Building renovations increase the concentration of Aspergillus conidia in the air. In 2010, one wing of the hospital building was imploded due to structural problems. To evaluate the impact of building implosion on the concentration of fungi in the air, the demolition was performed in two phases: mechanical demolition of 30 m of the building, followed by implosion of the wing. Patients at high risk for aspergillosis were placed in protected wards. Air sampling was performed during mechanical demolition, on the day of implosion and after implosion. Total and specific fungal concentrations were compared in the different areas and periods of sampling, using the anova test. The incidence of IA in the year before and after implosion was calculated. The mean concentration of Aspergillus increased during mechanical demolition and on the day of implosion. However, in the most protected areas, there was no significant difference in the concentration of fungi. The incidence of invasive aspergillosis (cases per 1000 admissions) was 0.9 in the 12 months before, 0.4 during, and 0.5 in the 12 months after mechanical demolition (P > 0.05). Continuous monitoring of the quality of air and effective infection control measures are important to minimize the impact of building demolition.

  14. Local emission of primary air pollutants and its contribution to wet deposition and concentrations of aerosols and gases in ambient air in Japan

    NASA Astrophysics Data System (ADS)

    Aikawa, Masahide; Hiraki, Takatoshi; Tomoyose, Nobutaka; Ohizumi, Tsuyoshi; Noguchi, Izumi; Murano, Kentaro; Mukai, Hitoshi

    2013-11-01

    We studied wet deposition by precipitation and the concentrations of aerosols and gases in ambient air in relation to the primary air pollutants discharged from domestic areas. The concentrations of aerosols and gases were influenced by nearby emissions except for non-sea-salt SO, which is transported long distances. The area facing the Sea of Japan showed much larger wet deposition than other areas, although the domestic emissions of the primary air pollutants there were small and showed a peak in wet deposition from October to March, as distinct from April to September in other areas. We performed the correlation analyses between wet deposition of each component and the product of the concentrations of corresponding aerosols and gases in ambient air and the two-thirds power of the precipitation. From the results, following scavenging processes were suggested. • Sulfate and ammonium were scavenged in precipitation as particulate matter such as (NH4)2SO4 and NH4HSO4. • Nitrate was scavenged mainly in precipitation through gaseous HNO3. • Ammonium was complementarily scavenged in precipitation through aerosols such as (NH4)2SO4 and NH4HSO4 and through gaseous NH3.

  15. BTEX air concentrations and self-reported common health problems in gasoline sellers from Cotonou, Benin.

    PubMed

    Tohon, Honesty Gbèdolo; Fayomi, Benjamin; Valcke, Mathieu; Coppieters, Yves; Bouland, Catherine

    2015-01-01

    To examine the relation between BTEX exposure levels and common self-reported health problems in 140 gasoline sellers in Cotonou, Benin, a questionnaire documenting their socioeconomic status and their health problems was used, whereas 18 of them went through semi-directed qualitative individual interviews and 17 had air samples taken on their workplace for BTEX analysis. Median concentrations for BTEX were significantly lower on official (range of medians: 54-207 μg/m³, n = 9) vs unofficial (148-1449 μg/m³, n = 8) gasoline-selling sites (p < 0.05). Self-reported health problems were less frequently reported in sellers from unofficial vs official selling sites (p < 0.05), because, as suggested by the semi-directed interviews, of their fear of losing their important, but illegal, source of income. Concluding, this study has combined quantitative and qualitative methodological approaches to account for the complex socioeconomic and environmental conditions of the investigated sellers, leading to their, in some cases, preoccupying BTEX exposure.

  16. Modeling the uptake of neutral organic chemicals on XAD passive air samplers under variable temperatures, external wind speeds and ambient air concentrations (PAS-SIM).

    PubMed

    Armitage, James M; Hayward, Stephen J; Wania, Frank

    2013-01-01

    The main objective of this study was to evaluate the performance and demonstrate the utility of a fugacity-based model of XAD passive air samplers (XAD-PAS) designed to simulate the uptake of neutral organic chemicals under variable temperatures, external wind speeds and ambient air concentrations. The model (PAS-SIM) simulates the transport of the chemical across the air-side boundary layer and within the sampler medium, which is segmented into a user-defined number of thin layers. Model performance was evaluated using data for polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) from a field calibration study (i.e., active and XAD-PAS data) conducted in Egbert, Ontario, Canada. With some exceptions, modeled PAS uptake curves are in good agreement with the empirical PAS data. The results are highly encouraging, given the uncertainty in the active air sampler data used as input and other uncertainties related to model parametrization (e.g., sampler-air partition coefficients, the influence of wind speed on sampling rates). The study supports the further development and evaluation of the PAS-SIM model as a diagnostic (e.g., to aid interpretation of calibration studies and monitoring data) and prognostic (e.g., to inform design of future passive air sampling campaigns) tool.

  17. Weekday/Weekend Differences in Ambient Concentrations of Primary and Secondary Air Pollutants

    NASA Astrophysics Data System (ADS)

    Blanchard, C. L.

    2004-12-01

    We evaluated the differences between mean day-of-week ambient concentrations of ozone precursors, ozone, and other secondary species using 1998-2003 ambient air-pollutant data from monitoring sites in 23 states in New England, the Midwest, the mid-Atlantic, and isolated urban areas in the western and southern U.S. For CO, NO, and NOx, we examined different times and averaging intervals: hourly (6 am and noon), three-hour averages (6-9 am, 9 am-12 noon, 12 noon-3 pm), and nine-hour daytime averages (6 am-3 pm). The median decreases at 6 am and noon bracketed the median daytime (6 am to 3 pm) decreases and closely represented the decreases occurring for the 3-hour averaging times 6 am-9 am and 12 noon-3 pm. In all areas and at both 6 am and noon, substantial declines in ambient concentrations of NO, NO2, and NOx occurred on weekends. Relative to Wednesdays, the median declines in 6 am Sunday ambient NO and NOx levels were 70.6 percent (interquartile [IQ] range 60.3-77.9 percent) and 57.5 percent (IQ range 47.2-63.4 percent), respectively; the median declines of 6 am Saturday NO and NOx levels were 52.7 percent (IQ range 40.8 to 61.8) and 40.1 percent (IQ range 33.0 to 48.1), respectively (204 sites with NO, NO2, and/or NOx). Most decreases were statistically significant (e.g., 173 NO sites, 170 with lower 6 am concentrations on Sundays than on Wednesdays, 153 statistically significant [p<0.01] decreases). The median decreases in ambient CO concentrations were smaller than those for NO and NOx. Relative to Wednesdays, the median declines in 6 am ambient CO levels at 227 monitors were 41.5 percent (IQ range 30.6 to 53.0) on Sundays and 28.1 percent (IQ range 20.7 to 36.6) on Saturdays. Most decreases were statistically significant (e.g., 227 sites, 220 with lower 6 am concentrations on Sundays than on Wednesdays, 202 statistically significant [p<0.01] decreases). For PAMS hydrocarbon data, day-of-week means were determined for the 9 am-3 pm ambient concentrations of

  18. Optimal Modeling of Urban Ambient Air Ozone Concentration Based on Its Precursors' Concentrations and Temperature, Employing Genetic Programming and Genetic Algorithm.

    PubMed

    Mousavi, Seyed Mahmoud; Husseinzadeh, Danial; Alikhani, Sadegh

    2014-04-01

    Efficient models are required to predict the optimum values of ozone concentration in different levels of its precursors' concentrations and temperatures. A novel model based on the application of a genetic programming (GP) optimization is presented in this article. Ozone precursors' concentrations and run time average temperature have been chosen as model's parameters. Generalization performances of two different homemade models based on genetic programming and genetic algorithm (GA), which can be used for calculating theoretical ozone concentration, are compared with conventional semi-empirical model performance. Experimental data of Mashhad city ambient air have been employed to investigate the prediction ability of properly trained GP, GA, and conventional semi-empirical models. It is clearly demonstrated that the in-house algorithm which is used for the model based on GP, provides better generalization performance over the model optimized with GA and the conventional semi-empirical ones. The proposed model is found accurate enough and can be used for urban air ozone concentration prediction.

  19. Background concentrations of individual and total volatile organic compounds in residential indoor air of Schleswig-Holstein, Germany.

    PubMed

    Hippelein, Martin

    2004-09-01

    During a monitoring campaign concentrations of volatile organic compounds (VOCs) were measured in indoor air of 79 dwellings where occupants had not complained about health problems or unpleasant odour. Parameters monitored were the individual concentration of 68 VOCs and the total concentration of all VOCs inside the room. VOCs adsorbed by Tenax TA were then analysed by means of thermal desorption, gas chromatography and mass spectrometry. The analytical procedure and quantification was done according to the recommendation of the ECA-IAQ Working Group 13 which gave a definition of the total volatile organic compound (TVOC) concentration. Using this recommendation TVOC-concentrations ranged between 33 and 1600 microg m(-3) with a median of 289 microg m(-3). Compounds found in every sample and with the highest concentrations were 2-propanol, alpha-pinene and toluene. Save for a few samples, all concentrations measured have been a factor 2 to 10 lower, compared to data from similar studies. Only a few terpenes and aldehydes were found exceeding published reference data or odour threshold concentrations. However, it has been found that sampling and analysing methods do have a considerable impact on the results, making direct comparisons of studies somewhat questionable. 47% of all samples revealed concentrations exceeding the threshold value of 300 microg TVOC m(-3) set by the German Federal Environmental Agency as a target for indoor air quality. Using the TVOC concentration as defined in the ECA-IAQ methodology is instrumental in assessing exposure to VOCs and identifying sources of VOCs. The background concentrations determined in this study can be used to discuss and interpret target values for individual and total volatile organic compounds in indoor air.

  20. Comparison of DAC and MONACO DSMC Codes with Flat Plate Simulation

    NASA Technical Reports Server (NTRS)

    Padilla, Jose F.

    2010-01-01

    Various implementations of the direct simulation Monte Carlo (DSMC) method exist in academia, government and industry. By comparing implementations, deficiencies and merits of each can be discovered. This document reports comparisons between DSMC Analysis Code (DAC) and MONACO. DAC is NASA's standard DSMC production code and MONACO is a research DSMC code developed in academia. These codes have various differences; in particular, they employ distinct computational grid definitions. In this study, DAC and MONACO are compared by having each simulate a blunted flat plate wind tunnel test, using an identical volume mesh. Simulation expense and DSMC metrics are compared. In addition, flow results are compared with available laboratory data. Overall, this study revealed that both codes, excluding grid adaptation, performed similarly. For parallel processing, DAC was generally more efficient. As expected, code accuracy was mainly dependent on physical models employed.

  1. System design description for mini-dacs data acquisition and control system

    SciTech Connect

    Vargo, F.G. Jr.; Trujillo, L.T.; Smith, S.O.

    1994-09-30

    This document describes the hardware computer system, for the mini data acquisition and control system (DACS) that was fabricated by Los Alamos National Laboratory (LANL), to support the testing of the spare mixer pump for SY-101.

  2. Computer system design description for the spare pump mini-dacs data acquisition and control system

    SciTech Connect

    Vargo, G.F. Jr.

    1994-09-29

    The attached document outlines the computer software design for the mini data acquisition and control system (DACS), that supports the testing of the spare pump for Tank 241-SY-101, at the maintenance and storage facility (MASF).

  3. Seasonal variability of tritium and ion concentrations in rain at Kumamoto, Japan and back-trajectory analysis of air mass

    SciTech Connect

    Momoshima, N.; Sugihara, S.; Toyoshima, T.; Nagao, Y.; Takahashi, M.; Nakamura, Y.

    2008-07-15

    Tritium and major ion concentrations in rain were analyzed in Kumamoto (Japan)) between 2001 and 2006 to examine present tritium concentration and seasonal variation. The average tritium concentration was 0.36 {+-} 0.19 Bq/L (n=104) and higher tritium concentrations were observed in spring than the other seasons. Among the ions, non-sea-salt (nss) SO{sub 4}{sup 2}'- showed higher concentration in winter while other ions did not show marked increase in winter. Based on the back-trajectory analyses of air masses, the increase in tritium concentrations in spring arises from downward movement of naturally produced tritium from stratosphere to troposphere, while the increase of the nss-SO{sub 4}{sup 2-} concentrations in winter is due to long range transport of pollutants from China to Japan. (authors)

  4. Reduced European emissions of S and N--effects on air concentrations, deposition and soil water chemistry in Swedish forests.

    PubMed

    Pihl Karlsson, Gunilla; Akselsson, Cecilia; Hellsten, Sofie; Karlsson, Per Erik

    2011-12-01

    Changes in sulphur and nitrogen pollution in Swedish forests have been assessed in relation to European emission reductions, based on measurements in the Swedish Throughfall Monitoring Network. Measurements were analysed over 20 years with a focus on the 12-year period 1996 to 2008. Air concentrations of SO(2) and NO(2), have decreased. The SO(4)-deposition has decreased in parallel with the European emission reductions. Soil water SO(4)-concentrations have decreased at most sites but the pH, ANC and inorganic Al-concentrations indicated acidification recovery only at some of the sites. No changes in the bulk deposition of inorganic nitrogen could be demonstrated. Elevated NO(3)-concentrations in the soil water occurred at irregular occasions at some southern sites. Despite considerable air pollution emission reductions in Europe, acidification recovery in Swedish forests soils is slow. Nitrogen deposition to Swedish forests continues at elevated levels that may lead to leaching of nitrate to surface waters.

  5. Background Indoor Air Concentrations of Volatile Organic Compounds in North American Residences (1990 – 2005): A Compilation of Statistics for Assessing Vapor Intrusion

    EPA Pesticide Factsheets

    This technical report presents a summary of indoor air studies that measured background concentrations of VOCs in the indoor air of thousands of North American residences and an evaluation and compilation of their reported statistical information.

  6. Contributions of vehicular emissions and secondary formation to nitrous acid concentrations in ambient urban air in Tokyo in the winter.

    PubMed

    Nakashima, Yoshihiro; Sadanaga, Yasuhiro; Saito, Shinji; Hoshi, Junya; Ueno, Hiroyuki

    2017-03-15

    Nitrous acid (HONO) plays an important role in the formation of OH radicals, which are involved in photochemical oxidation. HONO concentrations in ambient air at urban sites have previously been measured, but very few studies have been performed in central Tokyo. In this study, HONO concentrations in ambient air in southeast central Tokyo (near Tokyo Bay) in winter were determined by incoherent cavity enhanced absorption spectroscopy. The O3, NO, NO2, and SO2 concentrations were simultaneously determined. The NO concentrations were used to classify the parts of the study period into types I (high pollution), II (medium pollution), and III (low pollution). The maximum HONO concentrations in the type I, II, and III periods were 7.1, 4.5, and 3.0ppbv, respectively. These concentrations were comparable to concentrations previously found in other Asian megacities. The mean HONO concentration varied diurnally, and HONO was depleted between 00:00 and 03:00 each day. The sampling site is surrounded by roads with high traffic loads, but vehicular emissions were estimated to contribute <10% of the HONO concentrations. Two positive and negative relative humidity dependences of the HONO to NO2 ratio were confirmed, implying the existence of the two different secondary formation process of HONO. The NO2 to HONO conversion rates at night in the type I, II, and III periods were 6.3×10(-3), 7.6×10(-3), and 4.2×10(-3)h(-1), respectively.

  7. Genomes of Candidatus Wolbachia bourtzisii wDacA and Candidatus Wolbachia pipientis wDacB from the Cochineal Insect Dactylopius coccus (Hemiptera: Dactylopiidae)

    PubMed Central

    Ramírez-Puebla, Shamayim T.; Ormeño-Orrillo, Ernesto; Vera-Ponce de León, Arturo; Lozano, Luis; Sanchez-Flores, Alejandro; Rosenblueth, Mónica; Martínez-Romero, Esperanza

    2016-01-01

    Dactylopius species, known as cochineal insects, are the source of the carminic acid dye used worldwide. The presence of two Wolbachia strains in Dactylopius coccus from Mexico was revealed by PCR amplification of wsp and sequencing of 16S rRNA genes. A metagenome analysis recovered the genome sequences of Candidatus Wolbachia bourtzisii wDacA (supergroup A) and Candidatus Wolbachia pipientis wDacB (supergroup B). Genome read coverage, as well as 16S rRNA clone sequencing, revealed that wDacB was more abundant than wDacA. The strains shared similar predicted metabolic capabilities that are common to Wolbachia, including riboflavin, ubiquinone, and heme biosynthesis, but lacked other vitamin and cofactor biosynthesis as well as glycolysis, the oxidative pentose phosphate pathway, and sugar uptake systems. A complete tricarboxylic acid cycle and gluconeogenesis were predicted as well as limited amino acid biosynthesis. Uptake and catabolism of proline were evidenced in Dactylopius Wolbachia strains. Both strains possessed WO-like phage regions and type I and type IV secretion systems. Several efflux systems found suggested the existence of metal toxicity within their host. Besides already described putative virulence factors like ankyrin domain proteins, VlrC homologs, and patatin-like proteins, putative novel virulence factors related to those found in intracellular pathogens like Legionella and Mycobacterium are highlighted for the first time in Wolbachia. Candidate genes identified in other Wolbachia that are likely involved in cytoplasmic incompatibility were found in wDacB but not in wDacA. PMID:27543297

  8. Genomes of Candidatus Wolbachia bourtzisii wDacA and Candidatus Wolbachia pipientis wDacB from the Cochineal Insect Dactylopius coccus (Hemiptera: Dactylopiidae).

    PubMed

    Ramírez-Puebla, Shamayim T; Ormeño-Orrillo, Ernesto; Vera-Ponce de León, Arturo; Lozano, Luis; Sanchez-Flores, Alejandro; Rosenblueth, Mónica; Martínez-Romero, Esperanza

    2016-10-13

    Dactylopius species, known as cochineal insects, are the source of the carminic acid dye used worldwide. The presence of two Wolbachia strains in Dactylopius coccus from Mexico was revealed by PCR amplification of wsp and sequencing of 16S rRNA genes. A metagenome analysis recovered the genome sequences of Candidatus Wolbachia bourtzisii wDacA (supergroup A) and Candidatus Wolbachia pipientis wDacB (supergroup B). Genome read coverage, as well as 16S rRNA clone sequencing, revealed that wDacB was more abundant than wDacA. The strains shared similar predicted metabolic capabilities that are common to Wolbachia, including riboflavin, ubiquinone, and heme biosynthesis, but lacked other vitamin and cofactor biosynthesis as well as glycolysis, the oxidative pentose phosphate pathway, and sugar uptake systems. A complete tricarboxylic acid cycle and gluconeogenesis were predicted as well as limited amino acid biosynthesis. Uptake and catabolism of proline were evidenced in Dactylopius Wolbachia strains. Both strains possessed WO-like phage regions and type I and type IV secretion systems. Several efflux systems found suggested the existence of metal toxicity within their host. Besides already described putative virulence factors like ankyrin domain proteins, VlrC homologs, and patatin-like proteins, putative novel virulence factors related to those found in intracellular pathogens like Legionella and Mycobacterium are highlighted for the first time in Wolbachia Candidate genes identified in other Wolbachia that are likely involved in cytoplasmic incompatibility were found in wDacB but not in wDacA.

  9. Occurrence and Concentrations of Toxic VOCs in the Ambient Air of Gumi, an Electronics-Industrial City in Korea

    PubMed Central

    Baek, Sung-Ok; Suvarapu, Lakshmi Narayana; Seo, Young-Kyo

    2015-01-01

    This study was carried out to characterize the occurrence and concentrations of a variety of volatile organic compounds (VOCs) including aliphatic, aromatic, halogenated, nitrogenous, and carbonyl compounds, in the ambient air of Gumi City, where a large number of electronics industries are found. Two field monitoring campaigns were conducted for a one year period in 2003/2004 and 2010/2011 at several sampling sites in the city, representing industrial, residential and commercial areas. More than 80 individual compounds were determined in this study, and important compounds were then identified according to their abundance, ubiquity and toxicity. The monitoring data revealed toluene, trichloroethylene and acetaldehyde to be the most significant air toxics in the city, and their major sources were mainly industrial activities. On the other hand, there was no clear evidence of an industrial impact on the concentrations of benzene and formaldehyde in the ambient air of the city. Overall, seasonal variations were not as distinct as locational variations in the VOCs concentrations, whereas the within-day variations showed a typical pattern of urban air pollution, i.e., increase in the morning, decrease in the afternoon, and an increase again in the evening. Considerable decreases in the concentrations of VOCs from 2003 to 2011 were observed. The reductions in the ambient concentrations were confirmed further by the Korean PRTR data in industrial emissions within the city. Significant decreases in the concentrations of benzene and acetaldehyde were also noted, whereas formaldehyde appeared to be almost constant between the both campaigns. The decreased trends in the ambient levels were attributed not only to the stricter regulations for VOCs in Korea, but also to the voluntary agreement of major companies to reduce the use of organic solvents. In addition, a site planning project for an eco-friendly industrial complex is believed to play a contributory role in improving

  10. Occurrence and Concentrations of Toxic VOCs in the Ambient Air of Gumi, an Electronics-Industrial City in Korea.

    PubMed

    Baek, Sung-Ok; Suvarapu, Lakshmi Narayana; Seo, Young-Kyo

    2015-08-05

    This study was carried out to characterize the occurrence and concentrations of a variety of volatile organic compounds (VOCs) including aliphatic, aromatic, halogenated, nitrogenous, and carbonyl compounds, in the ambient air of Gumi City, where a large number of electronics industries are found. Two field monitoring campaigns were conducted for a one year period in 2003/2004 and 2010/2011 at several sampling sites in the city, representing industrial, residential and commercial areas. More than 80 individual compounds were determined in this study, and important compounds were then identified according to their abundance, ubiquity and toxicity. The monitoring data revealed toluene, trichloroethylene and acetaldehyde to be the most significant air toxics in the city, and their major sources were mainly industrial activities. On the other hand, there was no clear evidence of an industrial impact on the concentrations of benzene and formaldehyde in the ambient air of the city. Overall, seasonal variations were not as distinct as locational variations in the VOCs concentrations, whereas the within-day variations showed a typical pattern of urban air pollution, i.e., increase in the morning, decrease in the afternoon, and an increase again in the evening. Considerable decreases in the concentrations of VOCs from 2003 to 2011 were observed. The reductions in the ambient concentrations were confirmed further by the Korean PRTR data in industrial emissions within the city. Significant decreases in the concentrations of benzene and acetaldehyde were also noted, whereas formaldehyde appeared to be almost constant between the both campaigns. The decreased trends in the ambient levels were attributed not only to the stricter regulations for VOCs in Korea, but also to the voluntary agreement of major companies to reduce the use of organic solvents. In addition, a site planning project for an eco-friendly industrial complex is believed to play a contributory role in improving

  11. Wintertime PM 2.5 concentrations during persistent, multi-day cold-air pools in a mountain valley

    NASA Astrophysics Data System (ADS)

    Silcox, Geoffrey D.; Kelly, Kerry E.; Crosman, Erik T.; Whiteman, C. David; Allen, Bruce L.

    2012-01-01

    In January and February 2011, PM 2.5 concentrations in residential and nonresidential areas of Salt Lake City, Utah, were elevated during days with persistent multi-day stable layers or cold-air pools (CAPs). Under most conditions the PM 2.5 concentrations and atmospheric stability increased with time during these events, so that the highest PM 2.5 concentrations were observed in long-lived CAPs. PM 2.5 concentrations were generally observed to decrease with increasing elevation and were linearly related to the pre-sunrise valley heat deficit, an instantaneous measure of atmospheric stability. Decreases of up to 30 percent were observed as elevation increased from 1300 to 1600 m. During the CAP episode of 23-30 January, concentrations of PM 2.5 increased roughly linearly with time at all elevations at the rate of about 6 μg (m 3 day) -1. Higher elevation sites also experienced more rapid influxes of clean air during the mix-out of a CAP on 16 January, although short-lived episodes of higher concentrations occurred at times when polluted air was carried upslope from the residual CAP that persisted at lower elevations.

  12. Comparison of background levels of culturable fungal spore concentrations in indoor and outdoor air in southeastern Austria

    NASA Astrophysics Data System (ADS)

    Haas, D.; Habib, J.; Luxner, J.; Galler, H.; Zarfel, G.; Schlacher, R.; Friedl, H.; Reinthaler, F. F.

    2014-12-01

    Background concentrations of airborne fungi are indispensable criteria for an assessment of fungal concentrations indoors and in the ambient air. The goal of this study was to define the natural background values of culturable fungal spore concentrations as reference values for the assessment of moldy buildings. The concentrations of culturable fungi were determined outdoors as well as indoors in 185 dwellings without visible mold, obvious moisture problems or musty odor. Samples were collected using the MAS-100® microbiological air sampler. The study shows a characteristic seasonal influence on the background levels of Cladosporium, Penicillium and Aspergillus. Cladosporium sp. had a strong outdoor presence, whereas Aspergillus sp. and Penicillium sp. were typical indoor fungi. For the region of Styria, the median outdoor concentrations are between 100 and 940 cfu/m³ for culturable xerophilic fungi in the course of the year. Indoors, median background levels are between 180 and 420 cfu/m³ for xerophilic fungi. The I/O ratios of the airborne fungal spore concentrations were between 0.2 and 2.0. For the assessment of indoor and outdoor air samples the dominant genera Cladosporium, Penicillium and Aspergillus should receive special consideration.

  13. Methods for detecting and estimating population threshold concentrations for air pollution-related mortality with exposure measurement error

    SciTech Connect

    Cakmak, S.; Burnett, R.T.; Krewski, D.

    1999-06-01

    The association between daily fluctuations in ambient particulate matter and daily variations in nonaccidental mortality have been extensively investigated. Although it is now widely recognized that such an association exists, the form of the concentration-response model is still in question. Linear, no threshold and linear threshold models have been most commonly examined. In this paper the authors considered methods to detect and estimate threshold concentrations using time series data of daily mortality rates and air pollution concentrations. Because exposure is measured with error, they also considered the influence of measurement error in distinguishing between these two completing model specifications. The methods were illustrated on a 15-year daily time series of nonaccidental mortality and particulate air pollution data in Toronto, Canada. Nonparametric smoothed representations of the association between mortality and air pollution were adequate to graphically distinguish between these two forms. Weighted nonlinear regression methods for relative risk models were adequate to give nearly unbiased estimates of threshold concentrations even under conditions of extreme exposure measurement error. The uncertainty in the threshold estimates increased with the degree of exposure error. Regression models incorporating threshold concentrations could be clearly distinguished from linear relative risk models in the presence of exposure measurement error. The assumption of a linear model given that a threshold model was the correct form usually resulted in overestimates in the number of averted premature deaths, except for low threshold concentrations and large measurement error.

  14. [Air negative charge ion concentration and its relationships with meteorological factors in different ecological functional zones of Hefei City].

    PubMed

    Wei, Chaoling; Wang, Jingtao; Jiang, Yuelin; Zhang, Qingguo

    2006-11-01

    Air negative charge ion concentration (ANCIC) has a close relationship with air quality. The observations on the ANCIC, sunlight intensity, air temperature, and air relative humidity in different ecological functional zones of Hefei City from 2003 to 2004 showed that the diurnal change pattern of ANCIC was of single peak in sightseeing and habitation zones, dual peak in industrial zone, and complicated in commercial zone. Different ecological functional zones had different appearance time of their daily ANCIC extremum. The diurnal fluctuation of ANCIC was in the order of commercial zone > industrial zone > habitation zone and sightseeing zone. The annual change pattern of ANCIC in these zones was similar, being the highest in summer and lowest in winter, and the mean annual ANCIC was 819, 340, 149 and 126 ions x cm(-3), respectively. The most important meteorological factor affecting the ANCIC in Hefei City was air relative humidity, followed by sunlight intensity and air temperature. There was an exponential relationship between ANCIC and air relative humidity.

  15. LOCATING NEARBY SOURCES OF AIR POLLUTION BY NONPARAMETRIC REGRESSION OF ATMOSPHERIC CONCENTRATIONS ON WIND DIRECTION. (R826238)

    EPA Science Inventory

    The relationship of the concentration of air pollutants to wind direction has been determined by nonparametric regression using a Gaussian kernel. The results are smooth curves with error bars that allow for the accurate determination of the wind direction where the concentrat...

  16. IN VITRO EFFECTS OF PARTICULATE MATTER ON AIRWAY EPITHELIAL CELLS ISOLATED FROM CONCENTRATED AIR PARTICLES-EXPOSED SPONTANEOUS HYPERTENSIVE RATS

    EPA Science Inventory

    In vitro effects of particulate matter on airway epithelial cells isolated from concentrated air particles-exposed spontaneous hypertensive rats

    Ines Pagan, Urmila Kodavanti, Paul Evansky, Daniel L Costa and Janice A Dye. U.S. Environmental Protection Agency, ORD, National...

  17. INDOOR AIR CONCENTRATIONS OF ORGANOCHLORINE, ORGANOPHOSPHATE AND PYRETHROID PESTICIDES IN THE US: FOUR STUDIES, SIX STATES AND TWENTY YEARS

    EPA Science Inventory

    Pesticides used to control indoor pests have transitioned across the chemicals classes of organochlorine, organophosphate, and pyrethroid compounds from the 1980's to the present. This work summarizes the pesticide concentrations measured from the indoor air of homes from four st...

  18. A cryogenic DAC operating down to 4.2 K

    NASA Astrophysics Data System (ADS)

    Rahman, M. T.; Lehmann, T.

    2016-04-01

    This paper presents a 10 bit CMOS current steering digital to analog converter (DAC) that operates from room temperature to as low as 4.2 K. It works as the core part of a cryogenic Silicon quantum computer controller circuit producing rapid control gate voltage pulses for quantum bits (qubits) initialization. An improved analog calibration method with a unique unit current cell design is included in the D/A converter structure to overcome the extended cryogenic nonlinear and mismatch effects. The DAC retains its 10 bit linear monotonic behavior over the wide temperature range and it drives a 50 Ω load to 516 mV with a full scale rise time of 10 ns. The differential non-linearity (DNL) of the converter is 0.35LSB while its average power consumption is 32.18 mW from a 3 V power supply. The complete converter is fabricated using a commercial 0.5 μm 1 poly 3 metal Silicon on Sapphire (SOS) CMOS process. He briefly worked as a Lecturer in the Stamford University Bangladesh prior to starting his Ph.D. in 2012 in the School of Electrical Engineering and Telecommunications, UNSW. His Ph.D. research is focused on cryogenic electronics for Quantum Computer Interface. His main research interests are in designing data converters for ultra-low temperature electronics and biomedical applications. He spent two years as a Research Fellow at the University of Edinburgh, U.K., where he worked with biologically inspired artificial neural systems. From 1997 to 2000, he was an Assistant Professor in electronics at the Technical University of Denmark, working with low-power low-noise low-voltage analog and mixed analog-digital integrated circuits. From 2001 to 2003 he was Principal Engineer with Cochlear Ltd., Australia, where he was involved in the design of the world's first fully implantable cochlear implant. Today he is Associate Professor in microelectronics at the University of New South Wales, Australia. He has authored over 100 journal papers, conference papers, book chapters

  19. DAC is involved in the accumulation of the cytochrome b6/f complex in Arabidopsis.

    PubMed

    Xiao, Jianwei; Li, Jing; Ouyang, Min; Yun, Tao; He, Baoye; Ji, Daili; Ma, Jinfang; Chi, Wei; Lu, Congming; Zhang, Lixin

    2012-12-01

    The biogenesis and assembly of photosynthetic multisubunit protein complexes is assisted by a series of nucleus-encoded auxiliary protein factors. In this study, we characterize the dac mutant of Arabidopsis (Arabidopsis thaliana), which shows a severe defect in the accumulation of the cytochrome b(6)/f complex, and provide evidence suggesting that the efficiency of cytochrome b(6)/f complex assembly is affected in the mutant. DAC is a thylakoid membrane protein with two predicted transmembrane domains that is conserved from cyanobacteria to vascular plants. Yeast (Saccharomyces cerevisiae) two-hybrid and coimmunoprecipitation analyses revealed a specific interaction between DAC and PetD, a subunit of the cytochrome b(6)/f complex. However, DAC was found not to be an intrinsic component of the cytochrome b(6)/f complex. In vivo chloroplast protein labeling experiments showed that the labeling rates of the PetD and cytochrome f proteins were greatly reduced, whereas that of the cytochrome b(6) protein remained normal in the dac mutant. DAC appears to be a novel factor involved in the assembly/stabilization of the cytochrome b(6)/f complex, possibly through interaction with the PetD protein.

  20. Effect of poverty on the relationship between personal exposures and ambient concentrations of air pollutants in Ho Chi Minh City

    NASA Astrophysics Data System (ADS)

    Mehta, Sumi; Sbihi, Hind; Dinh, Tuan Nguyen; Xuan, Dan Vu; Le Thi Thanh, Loan; Thanh, Canh Truong; Le Truong, Giang; Cohen, Aaron; Brauer, Michael

    2014-10-01

    Socioeconomic factors often affect the distribution of exposure to air pollution. The relationships between health, air pollution, and poverty potentially have important public health and policy implications, especially in areas of Asia where air pollution levels are high and income disparity is large. The objective of the study was to characterize the levels, determinants of exposure, and relationships between children personal exposures and ambient concentrations of multiple air pollutants amongst different socioeconomic segments of the population of Ho Chi Minh City, Vietnam. Using repeated (N = 9) measures personal exposure monitoring and determinants of exposure modeling, we compared daily average PM2.5, PM10, PM2.5 absorbance and NO2 concentrations measured at ambient monitoring sites to measures of personal exposures for (N = 64) caregivers of young children from high and low socioeconomic groups in two districts (urban and peri-urban), across two seasons. Personal exposures for both PM sizes were significantly higher among the poor compared to non-poor participants in each district. Absolute levels of personal exposures were under-represented by ambient monitors with median individual longitudinal correlations between personal exposures and ambient concentrations of 0.4 for NO2, 0.6 for PM2.5 and PM10 and 0.7 for absorbance. Exposures of the non-poor were more highly correlated with ambient concentrations for both PM size fractions and absorbance while those for NO2 were not significantly affected by socioeconomic position. Determinants of exposure modeling indicated the importance of ventilation quality, time spent in the kitchen, air conditioner use and season as important determinant of exposure that are not fully captured by the differences in socioeconomic position. Our results underscore the need to evaluate how socioeconomic position affects exposure to air pollution. Here, differential exposure to major sources of pollution, further influenced by

  1. Air concentrations and wet deposition of major inorganic ions at five non-urban sites in China, 2001-2003

    NASA Astrophysics Data System (ADS)

    Aas, Wenche; Shao, Min; Jin, Lei; Larssen, Thorjørn; Zhao, Dawei; Xiang, Renjun; Zhang, Jinhong; Xiao, Jinsong; Duan, Lei

    Air and precipitation measurements at five sites were undertaken from 2001 to 2003 in four different provinces in China, as part of the acid rain monitoring program IMPACTS. The sites were located in Tie Shan Ping (TSP) in Chongqing, Cai Jia Tang (CJT) in Hunan, Lei Gong Shan (LGS) and Liu Chong Guan (LCG) in Guizhou and Li Xi He (LXH) in Guangdong. The site characteristics are quite varied with TSP and LCG located relatively near big cites while the three others are situated in more regionally representative areas. The distances to urban centres are reflected in the air pollution concentrations, with annual average concentrations of SO 2 ranging from 0.5 to above 40 μg S m -3. The main components in the airborne particles are (NH 4) 2SO 4 and CaSO 4. Reduced nitrogen has a considerably higher concentration level than oxidised nitrogen, reflecting the high ammonia emissions from agriculture. The gas/particle ratio for the nitrogen compounds is about 1:1 at all the three intensive measurement sites, while for sulphur it varies from 2.5 to 0.5 depending on the distance to the emission sources. As in air, the predominant ions in precipitation are sulphate, calcium and ammonium. The volume weighted annual concentration of sulphate ranges from about 70 μeq l -1 at the most rural site (LGS) to about 200 μeq l -1 at TSP and LCG. The calcium concentration ranges from 25 to 250 μeq l -1, while the total nitrogen concentration is between 30 and 150 μeq l -1; ammonium is generally twice as high as nitrate. China's acid rain research has traditionally been focused on urban sites, but these measurements show a significant influence of long range transported air pollutants to rural areas in China. The concentration levels are significantly higher than seen in most other parts of the world.

  2. Evaluation of background soil and air polychlorinated biphenyl (PCB) concentrations on a hill at the outskirts of a metropolitan city.

    PubMed

    Kuzu, S Levent; Saral, Arslan; Güneş, Gülten; Karadeniz, Aykut

    2016-07-01

    Air and soil sampling was conducted inside a forested area for 22 months. The sampling location is situated to the north of a metropolitan city. Average atmospheric gas and particle concentrations were found to be 180 and 28 pg m(-3) respectively, while that of soil phase was detected to be 3.2 ng g(-1) on dry matter, The congener pairs of PCB#4-10 had the highest contribution to each medium. TEQ concentration was 0.10 pg m(-3), 0.07 pg m(-3), 21.92 pg g(-1), for gas, particle and soil phases, respectively. PCB#126 and PCB#169 contributed to over 99% of the entire TEQ concentrations for each medium. Local sources were investigated by conditional probability function (CPF) and soil/air fugacity. Landfilling area and medical waste incinerator, located to the 8 km northeast, contributed to ambient concentrations, especially in terms of dioxin-like congeners. The industrial settlement (called Dilovasi being to the east southeast of 60 km distant) contributed from southeast direction. Further sources were identified by potential source contribution function (PSCF). Sources at close proximity had high contribution. Air mass transportation from Aliaga industrial region (being to the southwest of 300 km distant) moderately contributed to ambient concentrations. Low molecular weight congeners were released from soil body. 5-CBs and 6-CBs were close to equilibrium state between soil/air interfaces. PCB#171 was close to equilibrium and PCB#180 was likely to evaporate from soil, which constitute 7-CBs. PCB#199, representing 8-CBs deposited to soil. 9-CB (PCB#207) was in equilibrium between soil and air phases.

  3. Analysis of mobile source air toxics (MSATs)–Near-Road VOC and carbonyl concentrations

    EPA Science Inventory

    Exposures to mobile source air toxics (MSATs) have been associated with numerous adverse health effects. While thousands of air toxic compounds are emitted from mobile sources, a subset of compounds are considered high priority due to their significant contribution to cancer and...

  4. Diagnostic Analysis of Ozone Concentrations Simulated by Two Regional-Scale Air Quality Models

    EPA Science Inventory

    Since the Community Multiscale Air Quality modeling system (CMAQ) and the Weather Research and Forecasting with Chemistry model (WRF/Chem) use different approaches to simulate the interaction of meteorology and chemistry, this study compares the CMAQ and WRF/Chem air quality simu...

  5. SciDAC-Center for Plasma Edge Simulation

    SciTech Connect

    Chang, Choong Seock

    2012-06-04

    The SciDAC ProtoFSP Center for Plasma Edge Simulation (CPES) [http://www.cims.nyu.edu/cpes/] was awarded to New York University, Courant Institute of Mathematical Sciences in FY 2006. C.S. Chang was the institutional and national project PI. It's mission was 1) to build kinetic simulation code applicable to tokamak edge region including magnetic divertor geometry, 2) to build a computer science framework which can integrate the kinetic code with MHD/fluid codes in multiscale, 3) to conduct scientific research using the developed tools. CPES has built two such edge kinetic codes XGC0 and XGC1, which are still the only working kinetic edge plasma codes capable of including the diverted magnetic field geometry. CPES has also built the code coupling framework EFFIS (End-to-end Framework for Fusion Integrated Simulation), which incubated and used the Adios (www.olcf.ornl.gov/center-projects/adios/) and eSiMon (http://www.olcf.ornl.gov/center-projects/esimmon/) technologies, together with the Kepler technology.

  6. A 12-bit, low-voltage, nanoampere-based, ultralow-power, ultralow-glitch current-steering DAC for HDTV

    NASA Astrophysics Data System (ADS)

    Azhari, Seyed Javad; Monfaredi, Khalil; Amiri, Salar

    2012-11-01

    In this paper, a novel 12-bit current-steering binary-weighted digital-to-analog converter (DAC) based on nanoampere bits is designed and modified for high-definition television (HDTV) applications. As a part of a widely used consumer appliance, it is aimed to be such designed to consume power as low as possible. Hence, as a distinguished idea, prime concentration is focused on the reduction of the currents providing the bits of the proposed DAC. To do this, current mirrors operating in the weak inversion region are arranged to establish the least significant bit (LSB) current as low as 10 nA while the power supply is also reduced to 1 V, resulting to an ultralow power of 52.9 μW. Many other powerful ideas are then deliberately combined to maintain both high speed and very low glitches required for HDTV application despite those ultralow currents and power. The result is a speed of 100 MS/s, an ultralow glitch of ≃10.91 fAs, |INL| ≤ 0.988 LSB, |DNL| ≤ 0.99 LSB, and a spurious-free dynamic range of ≃73 dB. These results caused the proposed DAC to execute a distinguished overall performance (defined as figure of merit) greatly better than some other advanced ones by outstanding ratios of 77 to 277,185. Hspice simulations with the SMIC 0.18-μm complementary metal-oxide semiconductor technology have been used to validate the proposed circuit. Performance evaluation of the proposed DAC versus Monte Carlo simulations and also a wide range of temperature variations proved both its well mismatch insensitivity and thermal stability.

  7. Effect of the fuel/air mixture concentration distribution on the dynamics of a low-emission combustor

    NASA Astrophysics Data System (ADS)

    Vasil'ev, V. D.; Bulysova, L. A.; Berne, A. L.

    2016-12-01

    An investigation of the low-emission premixed combustion in a conventional combustor is presented. The main problem encountered is the pressure fluctuations induced under certain operating conditions of the combustor. Low-emission operation of the combustor was studied numerically and experimentally. The effect of the concentration distribution at the outlet from the mixing zone on the position and macrostructure of the flame and the combustion stability was investigated at various excess air factors corresponding various GTU loads. It is demonstrated that, for a given excess air factor, there exists the concentration profile such that the interaction of the flame front with dominating flow structures results in excitation of the low-frequency combustion instability. The factors responsible for high-amplitude pressure fluctuations are examined. It is shown that the combustion stability can be estimated using a calculated criterion. Its direct relationship with pressure fluctuation amplitudes is described. The effect of the air pressure in a combustor on the flame macrostructure and the combustion stability was studied. It is shown that an increase in the combustor pressure has no considerable effect on the processes in the combustor. However, a change in the chemical reaction rates affects the stable combustion boundary. In this case, the combustion stability is achieved with higher nonuniformity of the fuel-air mixture entering the combustion zone. The experimental boundaries of stable combustion envelope at an air pressure of 350 and 1500 kPa are presented.

  8. Passive-sampler derived air concentrations of persistent organic pollutants on a north-south transect in Chile.

    PubMed

    Pozo, Karla; Harner, Tom; Shoeib, Mahiba; Urrutia, Roberto; Barra, Ricardo; Parra, Oscar; Focardi, Silvano

    2004-12-15

    Passive air samplers consisting of polyurethane foam (PUF) disks, were deployed in six locations in Chile along a north-south transect to investigate gas-phase concentrations of polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), and polybrominated diphenyl ethers (PBDEs). The study provides new information on air concentrations of these persistent organic pollutants (POPs) which is lacking in this region. It also provides insight into potential sources and long-range transport (LRT). The samplers were deployed for a 2-month period in five remote sites and one site in the city of Concepción. Mean concentrations (pg m(-3)) for sigmaPCB were 4.7 +/- 2.7 at remote sites and 53 +/- 13 in Concepción. PCB levels at remote sites were related to proximity to urban source regions and/or air back trajectories. With the exception of endosulfan I, mean concentrations (pg m(-3)) of OCPs at background sites were consistently low: 5.4 +/- 1.4 for alpha-HCH, 7.0 +/- 1.1 for gamma-HCH, 2.5 +/- 0.5 for TC, 2.5 +/- 0.6 for CC, 1.9 +/- 1.2 for dieldrin, and less than 3.5 for toxaphene. Endosulfan I showed a decreasing concentration gradient from 99 to 3.5 pg m(-3) from the north to south of Chile. Concentrations of OCPs in the Concepción City were generally 10-20 times higher than at the background sites suggesting continued usage and/or re-emission from past use. For instance, at remote sites, the alpha/gamma ratio (0.76) was typical of background air, while the ratio in Concepción (0.12) was consistent with fresh use of gamma-HCH. Levels of sigmaPBDEs were below the detection limit of 6 pg m(-3) at all sites.

  9. Relationships between ozone photolysis rates and peroxy radical concentrations in clean marine air over the Southern Ocean

    NASA Astrophysics Data System (ADS)

    Penkett, S. A.; Monks, P. S.; Carpenter, L. J.; Clemitshaw, K. C.; Ayers, G. P.; Gillett, R. W.; Galbally, I. E.; Meyer, C. P.

    1997-06-01

    Measurements of the sum of inorganic and organic peroxy radicals (RO2) and photolysis rate coefficients J(NO2) and J(O1D) have been made at Cape Grim, Tasmania in the course of a comprehensive experiment which studied photochemistry in the unpolluted marine boundary layer. The SOAPEX (Southern Ocean Atmospheric Photochemistry Experiment) campaign included measurements of ozone, peroxides, nitrogen oxides, water vapor, and many other parameters. This first full length paper concerned with the experiment focuses on the types of relationships observed between peroxy radicals and J(NO2), J(O1D) and √[J(O1D)] in different air masses in which ozone is either produced or destroyed by photochemistry. It was found that in baseline air with ozone loss, RO2 was proportional to √[J(O1D)], whereas in more polluted air RO2 was proportional to J(O1D). Simple algorithms were derived to explain these relationships and also to calculate the concentrations of OH radicals in baseline air from the instantaneous RO2 concentrations. The signal to noise ratio of the peroxy radical measurements was up to 10 for 1-min values and much higher than in other previous deployments of the instrument in the northern hemisphere, leading to the confident determination of the relationships between RO2 and J(O1D) in different conditions. The absolute concentration Of RO2 determined in these experiments is in some doubt, but this does not affect our conclusions concerned either with the behavior of peroxy radicals with changing light levels or with the concentrations of OH calculated from RO2. The results provide confidence that the level of understanding of the photochemistry of ozone leading to the production of peroxide via recombination of peroxy radicals in clean air environments is well advanced.

  10. Cardiovascular Effects in Adults with Metabolic Syndrome Exposed to Concentrated Ultrafine Air Pollution Particles

    EPA Science Inventory

    RATIONALE: Epidemiologic studies report associations between ambient air pollution particulate matter (PM) and various indices of cardiopulmonary morbidity and mortality. A leading hypothesis contends that smaller ultrafine (UF) particles induce a greater physiologic response bec...

  11. ASSESSING THE COMPARABILITY OF AMMONIUM, NITRATE AND SULFATE CONCENTRATIONS MEASURED BY THREE AIR QUALITY MONITORING NETWORKS

    EPA Science Inventory

    Airborne fine particulate matter across the United States is monitored by different networks, the three prevalent ones presently being the Clean Air Status and Trend Network (CASTNet), the Interagency Monitoring of PROtected Visual Environment Network (IMPROVE) and the Speciati...

  12. Short-term effects of air temperature on plasma metabolite concentrations in patients undergoing cardiac cattheterization.

    EPA Science Inventory

    BACKGROUND: Epidemiological studies have shown associations between air temperature and cardiovascular health outcomes. Metabolic dysregulation might also play a role in the development of cardiovascular disease.OBJECTIVES: To investigate short-term temperature effects on metabol...

  13. REVIEW OF CONCENTRATION STANDARDS AND GUIDELINES FOR FUNGI IN INDOOR AIR

    EPA Science Inventory

    The paper reviews and compares existing guidelines for indoor airborne fungi, discusses limitations of existing guidelines, and identifies research needs that should contribute to the development of realistic and useful guidelines for these important air pollutants. (NOTE: Exposu...

  14. Radon ((222)Rn) concentration in indoor air near the coal mining area of Nui Beo, North of Vietnam.

    PubMed

    Nhan, Dang Duc; Fernando, Carvalho P; Thu Ha, Nguyen Thi; Long, Nguyen Quang; Thuan, Dao Dinh; Fonseca, Heloisa

    2012-08-01

    Concentrations of radioactive radon gas ((222)Rn) were measured using passive monitors based on LR115 solid state track detectors during June-July 2010 in indoor air of dwellings in the Nui Beo coal mining area, mostly in Cam Pha and Ha Long coastal towns, Quang Ninh province, in the North of Vietnam. Global results of (222)Rn concentrations indoors varied from ≤6 to 145 Bq m(-3) averaging 46 ± 26 Bq m(-3) (n = 37), with a median value of 47 Bq m(-3). This was similar to outdoor (222)Rn concentrations in the region, averaging 43 ± 19 Bq m(-3) (n = 10), with a median value of 44 Bq m(-3). Indoor (222)Rn concentrations in the coastal town dwellings only were in average lower although not significantly different from indoor (222)Rn concentrations measured at the coal storage field near the harbor, 67 ± 4 Bq m(-3) (n = 3). Furthermore, there was no significant difference in the average (222)Rn concentration in indoor air measured in the coastal towns region and those at the touristic Tuan Chau Island located about 45 km south of the coal mine, in the Ha Long Bay. The indoor (222)Rn concentration in a floating house at the Bai Tu Long Bay, and assumed as the best estimate of the baseline (222)Rn in surface air, was 27 ± 3 Bq m(-3) (n = 3). Indoor average concentration of (222)Rn in dwellings at the Ha Noi city, inland and outside the coal mining area, was determined at 30 Bq m(-3). These results suggest that (222)Rn exhalation from the ground at the Nui Beo coal mining area may have contributed to generally increase (222)Rn concentration in the surface air of that region up to 1.7 times above the baseline value measured at the Bai Tu Long Bay and Ha Noi. The average indoor concentration of (222)Rn in Cam Pha-Ha Long area is about one-third of the value of the so-called Action Level set up by the US EPA of 148 Bq m(-3). Results suggest that there is no significant public health risk from (222)Rn exposure in the study region.

  15. Temperature Programmed Desorption of Quench-condensed Krypton and Acetone in Air; Selective Concentration of Ultra-trace Gas Components.

    PubMed

    Suzuki, Taku T; Sakaguchi, Isao

    2016-01-01

    Selective concentration of ultra-trace components in air-like gases has an important application in analyzing volatile organic compounds in the gas. In the present study, we examined quench-condensation of the sample gas on a ZnO substrate below 50 K followed by temperature programmed desorption (TPD) (low temperature TPD) as a selective gas concentration technique. We studied two specific gases in the normal air; krypton as an inert gas and acetone as a reactive gas. We evaluated the relationship between the operating condition of low temperature TPD and the lowest detection limit. In the case of krypton, we observed the selective concentration by exposing at 6 K followed by thermal desorption at about 60 K. On the other hand, no selectivity appeared for acetone although trace acetone was successfully concentrated. This is likely due to the solvent effect by a major component in the air, which is suggested to be water. We suggest that pre-condensation to remove the water component may improve the selectivity in the trace acetone analysis by low temperature TPD.

  16. Acceleration of the chemistry solver for modeling DI engine combustion using dynamic adaptive chemistry (DAC) schemes

    NASA Astrophysics Data System (ADS)

    Shi, Yu; Liang, Long; Ge, Hai-Wen; Reitz, Rolf D.

    2010-03-01

    Acceleration of the chemistry solver for engine combustion is of much interest due to the fact that in practical engine simulations extensive computational time is spent solving the fuel oxidation and emission formation chemistry. A dynamic adaptive chemistry (DAC) scheme based on a directed relation graph error propagation (DRGEP) method has been applied to study homogeneous charge compression ignition (HCCI) engine combustion with detailed chemistry (over 500 species) previously using an R-value-based breadth-first search (RBFS) algorithm, which significantly reduced computational times (by as much as 30-fold). The present paper extends the use of this on-the-fly kinetic mechanism reduction scheme to model combustion in direct-injection (DI) engines. It was found that the DAC scheme becomes less efficient when applied to DI engine simulations using a kinetic mechanism of relatively small size and the accuracy of the original DAC scheme decreases for conventional non-premixed combustion engine. The present study also focuses on determination of search-initiating species, involvement of the NOx chemistry, selection of a proper error tolerance, as well as treatment of the interaction of chemical heat release and the fuel spray. Both the DAC schemes were integrated into the ERC KIVA-3v2 code, and simulations were conducted to compare the two schemes. In general, the present DAC scheme has better efficiency and similar accuracy compared to the previous DAC scheme. The efficiency depends on the size of the chemical kinetics mechanism used and the engine operating conditions. For cases using a small n-heptane kinetic mechanism of 34 species, 30% of the computational time is saved, and 50% for a larger n-heptane kinetic mechanism of 61 species. The paper also demonstrates that by combining the present DAC scheme with an adaptive multi-grid chemistry (AMC) solver, it is feasible to simulate a direct-injection engine using a detailed n-heptane mechanism with 543 species

  17. Air pollution and associated human mortality: The role of air pollutant emissions, climate change and methane concentration increases during the industrial period

    NASA Astrophysics Data System (ADS)

    Fang, Y.; Naik, V.; Horowitz, L. W.; Mauzerall, D. L.

    2012-12-01

    Increases in surface ozone (O3) and fine particulate matter (≤ 2.5μm aerodynamic diameter, PM2.5) are associated with excess premature human mortalities. Here we estimate changes in surface O3 and PM2.5 since preindustrial (1860) times and the global present-day (2000) premature human mortalities associated with these changes. We go beyond previous work to analyze and differentiate the contribution of three factors: changes in emissions of short-lived air pollutants, climate change, and increased methane (CH4) concentrations, to air pollution levels and the associated premature mortalities. We use a coupled chemistry-climate model in conjunction with global population distributions in 2000 to estimate exposure attributable to concentration changes since 1860 from each factor. Attributable mortalities are estimated using health impact functions of long-term relative risk estimates for O3 and PM2.5 from the epidemiology literature. We find global mean surface PM2.5 and health-relevant O3 (defined as the maximum 6-month mean of 1-hour daily maximum O3 in a year) have increased by 8±0.16 μg/m3 and 30±0.16 ppbv, respectively, over this industrial period as a result of combined changes in emissions of air pollutants (EMIS), climate (CLIM) and CH4 concentrations (TCH4). EMIS, CLIM and TCH4 cause global average PM2.5 (O3) to change by +7.5±0.19 μg/m3 (+25±0.30 ppbv), +0.4±0.17 μg/m3 (+0.5±0.28 ppbv), and -0.02±0.01 μg/m3 (+4.3±0.33 ppbv), respectively. Total changes in PM2.5 are associated with 1.5 (95% confidence interval, CI, 1.0-2.5) million all-cause mortalities annually and in O3 are associated with 375 (95% CI, 129-592) thousand respiratory mortalities annually. Most air pollution mortality is driven by changes in emissions of short-lived air pollutants and their precursors (95% and 85% of mortalities from PM2.5 and O3 respectively). However, changing climate and increasing CH4 concentrations also increased premature mortality associated with air

  18. Air pollution and associated human mortality: the role of air pollutant emissions, climate change and methane concentration increases during the industrial period

    NASA Astrophysics Data System (ADS)

    Fang, Y.; Naik, V.; Horowitz, L. W.; Mauzerall, D. L.

    2012-09-01

    Increases in surface ozone (O3) and fine particulate matter (≤2.5 μm} aerodynamic diameter, PM2.5) are associated with excess premature human mortalities. Here we estimate changes in surface O3 and PM2.5 since preindustrial (1860) times and the global present-day (2000) premature human mortalities associated with these changes. We go beyond previous work to analyze and differentiate the contribution of three factors: changes in emissions of short-lived air pollutants, climate change, and increased methane (CH4) concentrations, to air pollution levels and the associated premature mortalities. We use a coupled chemistry-climate model in conjunction with global population distributions in 2000 to estimate exposure attributable to concentration changes since 1860 from each factor. Attributable mortalities are estimated using health impact functions of long-term relative risk estimates for O3 and PM2.5 from the epidemiology literature. We find global mean surface PM2.5 and health-relevant O3 (defined as the maximum 6-month mean of 1-h daily maximum O3 in a year) have increased by 8 ± 0.16 μg m-3 and 30 ± 0.16 ppbv, respectively, over this industrial period as a result of combined changes in emissions of air pollutants (EMIS), climate (CLIM) and CH4 concentrations (TCH4). EMIS, CLIM and TCH4 cause global average PM2.5(O3) to change by +7.5 ± 0.19 μg m-3 (+25 ± 0.30 ppbv), +0.4 ± 0.17 μg m-3 (+0.5 ± 0.28 ppbv), and -0.02 ± 0.01 μg m-3 (+4.3 ± 0.33 ppbv), respectively. Total changes in PM2.5 are associated with 1.5 (95% confidence interval, CI, 1.0-2.5) million all-cause mortalities annually and in O3 are associated with 375 (95% CI, 129-592) thousand respiratory mortalities annually. Most air pollution mortality is driven by changes in emissions of short-lived air pollutants and their precursors (95% and 85% of mortalities from PM2.5 and O3, respectively). However, changing climate and increasing CH4 concentrations also increased premature mortality

  19. Air pollution and associated human mortality: the role of air pollutant emissions, climate change and methane concentration increases from the preindustrial period to present

    NASA Astrophysics Data System (ADS)

    Fang, Y.; Naik, V.; Horowitz, L. W.; Mauzerall, D. L.

    2013-02-01

    Increases in surface ozone (O3) and fine particulate matter (≤2.5 μm aerodynamic diameter, PM2.5) are associated with excess premature human mortalities. We estimate changes in surface O3 and PM2.5 from pre-industrial (1860) to present (2000) and the global present-day (2000) premature human mortalities associated with these changes. We extend previous work to differentiate the contribution of changes in three factors: emissions of short-lived air pollutants, climate change, and increased methane (CH4) concentrations, to air pollution levels and associated premature mortalities. We use a coupled chemistry-climate model in conjunction with global population distributions in 2000 to estimate exposure attributable to concentration changes since 1860 from each factor. Attributable mortalities are estimated using health impact functions of long-term relative risk estimates for O3 and PM2.5 from the epidemiology literature. We find global mean surface PM2.5 and health-relevant O3 (defined as the maximum 6-month mean of 1-h daily maximum O3 in a year) have increased by 8 ± 0.16 μg m-3 and 30 ± 0.16 ppbv (results reported as annual average ±standard deviation of 10-yr model simulations), respectively, over this industrial period as a result of combined changes in emissions of air pollutants (EMIS), climate (CLIM) and CH4 concentrations (TCH4). EMIS, CLIM and TCH4 cause global population-weighted average PM2.5 (O35) to change by +7.5 ± 0.19 μg m-3 (+25 ± 0.30 ppbv), +0.4 ± 0.17 μg m-3 (+0.5 ± 0.28 ppbv), and 0.04 ± 0.24 μg m-3 (+4.3 ± 0.33 ppbv), respectively. Total global changes in PM2.5 are associated with 1.5 (95% confidence interval, CI, 1.2-1.8) million cardiopulmonary mortalities and 95 (95% CI, 44-144) thousand lung cancer mortalities annually and changes in O3 are associated with 375 (95% CI, 129-592) thousand respiratory mortalities annually. Most air pollution mortality is driven by changes in emissions of short-lived air pollutants and their

  20. [Method for evaluating the concentration of alpha radiation potential energy of thorium Rn-220 in the air].

    PubMed

    Swiatnicki, G; Domański, T

    1978-01-01

    The paper presents assumptions and a description of an improved method for measuring the potential energy of radon decay products in the air. The method is based on the detection of alpha radiation emitted by ThC', in properly selected time intervals after the process of air filtration, i.e. collecting thoron decay products on the filter has been finished. The method has been worked out for various duration of filtration, i.e. 1--15 min, with measuring time intervals from 10 to 180 min. The method obtained is fit for the measurements of concentrations in a wide range of variation. Radioactivity of the deposit is being calculated on the basis of comparative measurements of 239Pu source of known activity. The sensitivity of the method for the most sensitive range is 0.84 . 10(4) MeV/litre per 1 liter of air filtered.

  1. International system of units traceable results of Hg mass concentration at saturation in air from a newly developed measurement procedure.

    PubMed

    Quétel, Christophe R; Zampella, Mariavittoria; Brown, Richard J C; Ent, Hugo; Horvat, Milena; Paredes, Eduardo; Tunc, Murat

    2014-08-05

    Data most commonly used at present to calibrate measurements of mercury vapor concentrations in air come from a relationship known as the "Dumarey equation". It uses a fitting relationship to experimental results obtained nearly 30 years ago. The way these results relate to the international system of units (SI) is not known. This has caused difficulties for the specification and enforcement of limit values for mercury concentrations in air and in emissions to air as part of national or international legislation. Furthermore, there is a significant discrepancy (around 7% at room temperature) between the Dumarey data and data calculated from results of mercury vapor pressure measurements in the presence of only liquid mercury. As an attempt to solve some of these problems, a new measurement procedure is described for SI traceable results of gaseous Hg concentrations at saturation in milliliter samples of air. The aim was to propose a scheme as immune as possible to analytical biases. It was based on isotope dilution (ID) in the liquid phase with the (202)Hg enriched certified reference material ERM-AE640 and measurements of the mercury isotope ratios in ID blends, subsequent to a cold vapor generation step, by inductively coupled plasma mass spectrometry. The process developed involved a combination of interconnected valves and syringes operated by computer controlled pumps and ensured continuity under closed circuit conditions from the air sampling stage onward. Quantitative trapping of the gaseous mercury in the liquid phase was achieved with 11.5 μM KMnO4 in 2% HNO3. Mass concentrations at saturation found from five measurements under room temperature conditions were significantly higher (5.8% on average) than data calculated from the Dumarey equation, but in agreement (-1.2% lower on average) with data based on mercury vapor pressure measurement results. Relative expanded combined uncertainties were estimated following a model based approach. They ranged from 2

  2. Reformulated and alternative fuels: modeled impacts on regional air quality with special emphasis on surface ozone concentration.

    PubMed

    Schell, Benedikt; Ackermann, Ingmar J; Hass, Heinz

    2002-07-15

    The comprehensive European Air Pollution and Dispersion model system was used to estimate the impacts of the usage of reformulated and alternative fuels on regional air quality with special emphasis on surface ozone concentrations. A severe western European summer smog episode in July 1994 has been used as a reference, and the model predictions have been evaluated for this episode. A forecast simulation for the year 2005 (TREND) has been performed, including the future emission development based on the current legislation and technologies available. The results of the scenario TREND are used as a baseline for the other 2005 fuel scenarios, including fuel reformulation, fuel sulfur content, and compressed natural gas (CNG) as an alternative fuel. Compared to the year 1994, significant reductions in episode peak ozone concentrations and ozone grid hours are predicted for the TREND scenario. These reductions are even more pronounced within the investigated alternative and reformulated fuel scenarios. Especially, low sulfur fuels are appropriate for an immediate improvement in air quality, because they effect the emissions of the whole fleet. Furthermore, the simulation results indicate that the introduction of CNG vehicles would also enhance air quality with respect to ozone.

  3. The effect of low ventilation rate with elevated bioeffluent concentration on work performance, perceived indoor air quality and health symptoms.

    PubMed

    Maula, Henna; Hongisto, Valtteri; Naatula, Viivi; Haapakangas, Annu; Koskela, Hannu

    2017-04-05

    The aim of this laboratory experiment was to study the effects of ventilation rate, and related changes in air quality, predominantly bioeffluents, on work performance, perceived indoor air quality and health symptoms in a typical conditions of modern open-plan office with low material and equipment emissions. In Condition A, outdoor air flow rate of 28.2 l/s person (CO2 level 540 ppm) was applied and in Condition B, outdoor air flow rate was 2.3 l/s person (CO2 level 2260 ppm). CO2 concentration level was used as an indicator of bioeffluents. Performance was measured with seven different tasks which measure different cognitive processes. Thirty-six subjects participated in the experiment. The exposure time was 4 hours. Condition B had a weak negative effect on performance only in the information retrieval tasks. Condition B increased slightly subjective workload and perceived fatigue. No effects on health symptoms were found. The intensity of symptoms was low in both conditions. The experimental condition had an effect on perceived air quality and observed odour intensity only in the beginning of the session. Although the room temperature was controlled in both conditions, the heat was perceived to impair the performance more in Condition B. This article is protected by copyright. All rights reserved.

  4. AIRNET Data from Los Alamos National Laboratory: Air Concentration Data by Site and Isotope/Element

    DOE Data Explorer

    Ambient monitoring is the systematic, long-term assessment of pollutant levels by measuring the quantity and types of certain pollutants in the surrounding, outdoor air. The purpose of AIRNET, LANL's ambient air monitoring network, is to monitor locations where people live or work. The community of Los Alamos is downwind from LANL, so there are many monitoring stations in and around the town. AIRNET stations monitor 24 hours a day, 365 days of the year. Particulates are collected on a filter and analyzed every two weeks for identification of analytes and assessment of the potential impact on the public. Emissions measurement is the process of monitoring materials vented from buildings. Air samples are taken from building exhaust units, called stacks, and are then analyzed for particulate matter, tritium, and radioactive gases and vapors. A computer model uses the emission data to determine the dispersion. Stack monitoring is also used to measure emissions that cannot be measured by AIRNET stations.

  5. SAID Partial Wave Analyses from CNS DAC (Center for Nuclear Studies Data Analysis Center)

    DOE Data Explorer

    George Washington University (GW) has one of the largest university-based nuclear-physics groups in the nation. Many of the current and future projects are geared to Thomas Jefferson National Accelerator Facility (JLab) at Newport News, VA. JLab is the world's premier electron accelerator for nuclear physics, and GW is one of the charter members of the governing body of JLab, the Southeastern Universities Research Association (SURA). The George Washington Data Analysis Center (DAC) was created in 1998 by an agreement among the Department of Energy, Jefferson Lab, and the GW Center for Nuclear Studies.The activities of the DAC fall into four distinct categories: 1) Performing partial-wave analyses of fundamental two- and three-body reactions; 2) Maintenance of databases associated with these reactions; 3) Development of software to disseminate DAC results (as well as the results of competing model-independent analyses and potential approaches); and 4) Phenomenological and theoretical investigations which bridge the gap between theory and experiment; in particular, the extraction of N* and D * hadronic and electromagnetic couplings. Partial Wave Analyses (and the associated databases) available at GW are: Pion-Nucleon, Kaon-Nucleon, Nucleon-Nucleon, Pion Photoproduction, Pion Electroproduction, Kaon Photoproduction, Eta Photoproduction, Eta-Prime Photoproduction, Pion-Deuteron (elastic), and Pion-Deuteron to Proton+Proton. [Taken from http://www.gwu.edu/~ndl/dac.htm">http://www.gwu.edu/~ndl/dac.htm

  6. 10-bit segmented current steering DAC in 90nm CMOS technology

    NASA Astrophysics Data System (ADS)

    Bringas, R., Jr.; Dy, F.; Gerasta, O. J.

    2015-06-01

    This special project presents a 10-Bit 1Gs/s 1.2V/3.3V Digital-to-Analog Converter using1 Poly 9 Metal SAED 90-nm CMOS Technology intended for mixed-signal and power IC applications. To achieve maximum performance with minimum area, the DAC has been implemented in 6+4 Segmentation. The simulation results show a static performance of ±0.56 LSB INL and ±0.79 LSB DNL with a total layout chip area of 0.683 mm2.The segmented architecture is implemented using two sub DAC's, which are the LSB and MSB section with certain number bits. The DAC is designed using 4-BitBinary Weighted DAC for the LSB section and 6-BitThermometer-coded DAC for the MSB section. The thermometer-coded architecture provides the most optimized results in terms of linearity through reducing the clock feed-through effect especially in hot switching between multiple transistors. The binary- weighted architecture gives better linearity output in higher frequencies with better saturation in current sources.

  7. Can changing the timing of outdoor air intake reduce indoor concentrations of traffic-related pollutants in schools?

    PubMed

    MacNeill, M; Dobbin, N; St-Jean, M; Wallace, L; Marro, L; Shin, T; You, H; Kulka, R; Allen, R W; Wheeler, A J

    2016-10-01

    Traffic emissions have been associated with a wide range of adverse health effects. Many schools are situated close to major roads, and as children spend much of their day in school, methods to reduce traffic-related air pollutant concentrations in the school environment are warranted. One promising method to reduce pollutant concentrations in schools is to alter the timing of the ventilation so that high ventilation time periods do not correspond to rush hour traffic. Health Canada, in collaboration with the Ottawa-Carleton District School Board, tested the effect of this action by collecting traffic-related air pollution data from four schools in Ottawa, Canada, during October and November 2013. A baseline and intervention period was assessed in each school. There were statistically significant (P < 0.05) reductions in concentrations of most of the pollutants measured at the two late-start (9 AM start) schools, after adjusting for outdoor concentrations and the absolute indoor-outdoor temperature difference. The intervention at the early-start (8 AM start) schools did not have significant reductions in pollutant concentrations. Based on these findings, changing the timing of the ventilation may be a cost-effective mechanism of reducing traffic-related pollutants in late-start schools located near major roads.

  8. Investigation of indoor air volatile organic compounds concentration levels in dental settings and some related methodological issues.

    PubMed

    Santarsiero, Anna; Fuselli, Sergio; Piermattei, Alessandro; Morlino, Roberta; De Blasio, Giorgia; De Felice, Marco; Ortolani, Emanuela

    2009-01-01

    The assessment of indoor air volatile organic compounds (VOCs) concentration levels in dental settings has a big health relevance for the potentially massive occupational exposure to a lot of diverse contaminants. The comparison of the VOCs profile relative to indoor conditions and to the corresponding outdoor concentrations, as well as the discovery of possible correlations between specific dental activities and VOCs concentration variations are of utmost importance for offering a reliable characterization of risk for dentists and dental staff health. In this study we review the most relevant environmental studies addressing the VOCs contamination level in dental settings. We analyze the methodological problems this kind of study must face and we report preliminary results of an indoor air investigation, carried out at dental hospital in Italy, the "Ospedale odontoiatrico George Eastman" of Rome, in which general lines for the analysis of dental settings in environmental terms are sketched. The aim of this work is to identify the kind of problems a typical enclosed (non-industrial) environment indoor air investigation has to cope with by means of the analysis of a case study.

  9. Comparison of two different passive air samplers (PUF-PAS versus SIP-PAS) to determine time-integrated average air concentration of volatile hydrophobic organic pollutants

    NASA Astrophysics Data System (ADS)

    Kim, Seung-Kyu; Park, Jong-Eun

    2014-06-01

    Despite remarkable achievements with r some chemicals, a field-measurement technique has not been advanced for volatile hydrophobic organic chemicals (HOCs) that are the subjects of international concern. This study assesses the applicability of passive air sampling (PAS) by comparing PUF-PAS and its modified SIP-PAS which was made by impregnating XAD-4 powder into PUF, overviewing the principles of PAS, screening sensitive parameters, and determining the uncertainty range of PAS-derived concentration. The PAS air sampling rate determined in this study, corrected by a co-deployed low-volume active air sampler (LAS) for neutral PFCs as model chemicals, was ˜1.2 m3 day-1. Our assessment shows that the improved sorption capacity in a SIP lengthens PAS deployment duration by expanding the linear uptake range and then enlarges the effective air sampling volume and detection frequency of chemicals at trace level. Consequently, volatile chemicals can be collected during sufficiently long times without reaching equilibrium when using SIP, while this is not possible for PUF. The most sensitive parameter to influence PAS-derived CA was an air-side mass transfer coefficient (kA), implying the necessity of spiking depuration chemicals (DCs) because this parameter is strongly related with meteorological conditions. Uncertainty in partition coefficients (KPSM-A or KOA) influences PAS-derived CA to a greater extent with regard to lower KPSM-A chemicals. Also, the PAS-derived CA has an uncertainty range of a half level to a 3-fold higher level of the calculated one. This work is expected to establish solid grounds for the improvement of field measurement technique of HOCs.

  10. Short-term temperature-dependent air-surface exchange and atmospheric concentrations of polychlorinated naphthalenes and organochlorine pesticides

    SciTech Connect

    Lee, R.G.M.; Burnett, V.; Harner, T.; Jones, K.C.

    2000-02-01

    Atmospheric concentrations of five organochlorine (OC) pesticides, some of which have been banned for a number of years, and polychlorinated naphthalenes (PCNs) were measured at a U.K. site over periods of 6 h for 7 days resulting in 28 samples. Mean concentrations of the pesticides were {alpha}-HCH 90 pg m{sup {minus}3}, {gamma}-HCH 500, {rho},{rho}{prime}-DDE 8, dieldrin 63, endrin 22, and HCB 39. PCN mean homologue concentrations were {sub 3}CNs 67 pg m{sup {minus}3}, {sub 4}CNs 78, {sub 5}CNs 5, {sub 6}CNs 0.6, {sub 7}CNs 0.6, and {Sigma}PCNs 152. TEQ concentrations for those PCNs ascribed TEF values ranged between 0.36 and 3.6 fg m{sup {minus}3} which corresponds to {approximately}3.0--30% of the TEQ concentrations of PCDD/Fs at the same site. All the compounds measured, except HCB, exhibited a strong temperature-dependent diurnal cycling. Results from Clausius-Clapeyron plots show that pesticide concentrations were controlled by temperature-driven air-surface recycling throughout the first 5 days when stable atmospheric conditions were dominant, while during the last 2 days advection became more influential as more unstable and cooler weather started to influence the site. PCN concentrations were controlled primarily by a mixture of recycling and advection throughout the first 5 days and then by advection in the final 2 days, suggesting that there are ongoing emissions from diffuse point sources of PCNs into the U.K. atmosphere. This study provides further evidence of the rapid air-surface exchange of semivolatile organic compounds (SOCs) and shows how different factors alone or in combination can produce rapid changes in the atmospheric concentrations of past and present SOCs.

  11. A modeling framework for characterizing near-road air pollutant concentration at community scales

    EPA Science Inventory

    In this study, we combine information from transportation network, traffic emissions, and dispersion model to develop a framework to inform exposure estimates for traffic-related air pollutants (TRAPs) with a high spatial resolution. A Research LINE source dispersion model (R-LIN...

  12. Exposure to concentrated coarse air pollution particles causes mild cardiopulmonary effects in young healthy adults

    EPA Science Inventory

    Rationale: There is ample epidemiological and toxicological evidence that exposure to fme air pollution particles (PM2.5), which are primarily derived from combustion processes, can result in increased mortality and morbidity. There is less certainty as to the contribution of coa...

  13. Vascular Effects of a Subchronic Inhalation Exposure to Concentrated Ambient Air Particles in Atherosclerosis Susceptible Mice

    EPA Science Inventory

    Numerous studies have reported the adverse effects of particulate air pollution on cardiovascular function and disease. The causal physiochemical properties of particles and their mechanisms of action/injury remain unknown. This study examined the vascular effects in 15 wk old ma...

  14. Development and Evaluation of Land-Use Regression Models Using Modeled Air Quality Concentrations

    EPA Science Inventory

    Abstract Land-use regression (LUR) models have emerged as a preferred methodology for estimating individual exposure to ambient air pollution in epidemiologic studies in absence of subject-specific measurements. Although there is a growing literature focused on LUR evaluation, fu...

  15. Concentrations of vehicle-related air pollutants in an urban parking garage.

    PubMed

    Kim, Sung R; Dominici, Francesca; Buckley, Timothy J

    2007-11-01

    There is growing evidence that traffic-related air pollution poses a public health threat, yet the dynamics of human exposure are not well understood. The urban parking garage is a microenvironment that is of concern but has not been characterized. Using time-resolved measurement methods, we evaluated air toxics levels within an urban parking garage and assessed the influence of vehicle activity and type on their levels. Carbon monoxide (CO) and particle-bound polycyclic aromatic hydrocarbons (pPAH) were measured with direct-reading instruments. Volatile organic compounds (VOCs) were measured in 30 min intervals using a sorbent tube loaded sequential sampler. Vehicle volume and type were evaluated by video recording. Sampling was conducted from June 24 to July 17, 2002. We observed garage traffic median volumes of 71 counts/h on weekdays and 6 counts/h on weekends. The 12-fold reduction in traffic volume from weekday to weekend corresponded with a decrease in median air pollution that varied from a minimum 2- (CO) to a maximum 7 (pPAH)-fold. The actual 30-min median weekday and weekend values were: CO--2.6/1.2 ppm; pPAH--19/2.6 ng/m(3); 1,3-butadiene-0.5/0.2 microg/m(3), MTBE-7.4/0.4 microg/m(3); and benzene-2.7/0.3 microg/m(3). The influence of traffic was quantified using longitudinal models. The pollutant coefficients provide an indication of the average air pollution vehicle source contribution and ranged from 0.31 (CO) to 1.08 (pPAH) percent increase/vehicle count. For some pollutants, a slightly higher (0.5-0.6%) coefficient was observed for light-trucks relative to cars. This study has public health relevance in providing a unique assessment of air pollution levels and source contribution for the urban parking garage.

  16. 20 Years of Air-Water Gas Exchange Observations for Pesticides in the Western Arctic Ocean.

    PubMed

    Jantunen, Liisa M; Wong, Fiona; Gawor, Anya; Kylin, Henrik; Helm, Paul A; Stern, Gary A; Strachan, William M J; Burniston, Deborah A; Bidleman, Terry F

    2015-12-01

    The Arctic has been contaminated by legacy organochlorine pesticides (OCPs) and currently used pesticides (CUPs) through atmospheric transport and oceanic currents. Here we report the time trends and air-water exchange of OCPs and CUPs from research expeditions conducted between 1993 and 2013. Compounds determined in both air and water were trans- and cis-chlordanes (TC, CC), trans- and cis-nonachlors (TN, CN), heptachlor exo-epoxide (HEPX), dieldrin (DIEL), chlorobornanes (ΣCHBs and toxaphene), dacthal (DAC), endosulfans and metabolite endosulfan sulfate (ENDO-I, ENDO-II, and ENDO SUL), chlorothalonil (CHT), chlorpyrifos (CPF), and trifluralin (TFN). Pentachloronitrobenzene (PCNB and quintozene) and its soil metabolite pentachlorothianisole (PCTA) were also found in air. Concentrations of most OCPs declined in surface water, whereas some CUPs increased (ENDO-I, CHT, and TFN) or showed no significant change (CPF and DAC), and most compounds declined in air. Chlordane compound fractions TC/(TC + CC) and TC/(TC + CC + TN) decreased in water and air, while CC/(TC + CC + TN) increased. TN/(TC + CC + TN) also increased in air and slightly, but not significantly, in water. These changes suggest selective removal of more labile TC and/or a shift in chlordane sources. Water-air fugacity ratios indicated net volatilization (FR > 1.0) or near equilibrium (FR not significantly different from 1.0) for most OCPs but net deposition (FR < 1.0) for ΣCHBs. Net deposition was shown for ENDO-I on all expeditions, while the net exchange direction of other CUPs varied. Understanding the processes and current state of air-surface exchange helps to interpret environmental exposure and evaluate the effectiveness of international protocols and provides insights for the environmental fate of new and emerging chemicals.

  17. A gravimetric approach to providing SI traceability for concentration measurement results of mercury vapor at ambient air levels

    NASA Astrophysics Data System (ADS)

    Ent, Hugo; van Andel, Inge; Heemskerk, Maurice; van Otterloo, Peter; Bavius, Wijnand; Baldan, Annarita; Horvat, Milena; Brown, Richard J. C.; Quétel, Christophe R.

    2014-11-01

    Current measurement and calibration capabilities for mercury vapor in air are maintained at levels of 0.2-40 μg Hg m-3. In this work, a mercury vapor generator has been developed to establish metrological traceability to the international system of units (SI) for mercury vapor measurement results ≤15 ng Hg m-3, i.e. closer to realistic ambient air concentrations (1-2 ng Hg m-3) [1]. Innovations developed included a modified type of diffusion cell, a new measurement method to weigh the loss in (mercury) mass of these diffusion cells during use (ca. 6-8 μg mass difference between successive weighings), and a new housing for the diffusion cells to maximize flow characteristics and to minimize temperature variations and adsorption effects. The newly developed mercury vapor generator system was tested by using diffusion cells generating 0.8 and 16 ng Hg min-1. The results also show that the filter system, to produce mercury free air, is working properly. Furthermore, and most importantly, the system is producing a flow with a stable mercury vapor content. Some additional improvements are still required to allow the developed mercury vapor generator to produce SI traceable mercury vapor concentrations, based upon gravimetry, at much lower concentration levels and reduced measurement uncertainties than have been achieved previously. The challenges to be met are especially related to developing more robust diffusion cells and better mass measurement conditions. The developed mercury vapor generator will contribute to more reliable measurement results of mercury vapor at ambient and background air levels, and also to better safety standards and cost reductions in industrial processes, such as the liquefied natural gas field, where aluminum main cryogenic heat exchangers are used which are particularly prone to corrosion caused by mercury.

  18. Investigation of the concentration of bacteria and their cell envelope components in indoor air in two elementary schools.

    PubMed

    Liu, L J; Krahmer, M; Fox, A; Feigley, C E; Featherstone, A; Saraf, A; Larsson, L

    2000-11-01

    Bacterial cell envelope components are widely distributed in airborne dust, where they act as inflammatory agents causing respiratory symptoms. Measurements of these agents and other environmental factors are assessed in two elementary schools in a southeastern city in the United States. Muramic acid (MA) was used as a marker for bacterial peptidoglycan (PG), and 3-hydroxy fatty acids (3-OH FAs) were used as markers for Gram-negative bacterial lipopolysaccharide (LPS). Culturable bacteria were collected using an Andersen sampler with three different culture media. In addition, temperature (T), relative humidity (RH), and CO2 were continuously monitored. Concentrations of airborne MA and 3-OH FAs were correlated with total suspended particulate (TSP) levels. Outdoor MA (mean = 0.78-1.15 ng/m3) and 3-OH FA levels (mean = 2.19-2.18 ng/m3) were similar at the two schools. Indoor concentrations of airborne MA and 3-OH FAs differed significantly between schools (MA: 1.44 vs. 2.84 ng/m3; 3-OH FAs: 2.96 vs. 4.57 ng/m3). Although indoor MA levels were low, they were significantly related to teachers' perception of the severity of indoor air quality (IAQ) problems in their classrooms. Concentrations of CO2 correlated significantly with all bacteria measurements. Because CO2 levels were related to the number of occupants and the ventilation rates, these findings are consistent with the hypothesis that the children and teachers are sources of bacterial contamination. Many culturable bacteria present in indoor air are opportunistic organisms that can be infectious for compromised individuals, while both culturable and nonculturable bacterial remnants act as environmental toxins for both healthy and compromised individuals. Measuring the "total bacteria load" would be most accurate in assessing the biotoxicity of indoor air. Chemical analysis of MA and 3-OH FAs, when coupled with the conventional culture method, provides complementary information for assessing biocontamination

  19. Hypomethylating agent 5-aza-2'-deoxycytidine (DAC) ameliorates multiple sclerosis in mouse models.

    PubMed

    Mangano, Katia; Fagone, Paolo; Bendtzen, Klaus; Meroni, Pier Luigi; Quattrocchi, Cinzia; Mammana, Santa; Di Rosa, Michelino; Malaguarnera, Lucia; Coco, Marinella; Magro, Gaetano; Di Marco, Roberto; Nicoletti, Ferdinando

    2014-12-01

    Increasing evidence supports the role of epigenetics in the development of autoimmune disorders and the possibility of using epigenetic modifying drugs in the context of MS has not yet been investigated. We have explored the effect of the hypomethylating agent 5-aza-2'-deoxycytidine (DAC) in two murine models of experimental allergic encephalomyelitis (EAE). DAC treatment was associated with a significant amelioration of the clinical and histological hallmarks of EAE in both models. These effects were observed both in prophylactic and therapeutic regimens. The milder course of the disease was associated with a reduction in the number of spinal cord infiltrating lymphocytes and amelioration of the histopathological signs associated with EAE. In addition, increased transcript levels of anti-inflammatory cytokines and decreased mRNA expression of pro-inflammatory mediators were also observed. Finally, DAC treatment increased the percentage of circulating regulatory T cells by inducing Foxp3 expression via demethylation of a CpG island in Foxp3.

  20. Comparison of Ambient Radon Concentrations in Air in the Northern Mojave Desert from Continuous and Integrating Instruments

    SciTech Connect

    David S. Shafer; David McGraw; Lynn H. Karr; Greg McCurdy; Tammy L. Kluesner; Karen J. Gray; Jeffrey Tappen

    2010-05-18

    As part of a program to characterize and baseline environmental parameters, ambient radon-222 (Rn) monitoring was conducted in the rural community of Amargosa Valley, NV, the closest community to Yucca Mountain. Passive integrating and continuous Rn monitoring instruments were deployed adjacent to the Community Environmental Monitoring Program (CEMP) station in Amargosa Valley. The CEMP station provided real-time ambient gamma exposure and meteorological data used to correct the integrated Rn measurements, verified the meteorological data collected by the continuous Rn monitoring instrument, and for provided instrumentation for evaluating the relationships between meteorological conditions and Rn concentrations. Hourly Rn concentrations in air measured by the continuous Rn monitoring instrument (AlphaGUARD®) were compared to the average hourly values for the integrating Rn measurements (E-PERM®) by dividing the total Rn measurements by the number of hours the instruments were deployed. The results of the comparison indicated that average hourly ambient Rn concentrations as measured by both methods ranged from 0.2 to 0.4 pico-curies per liter of air. Ambient Rn values for the AlphaGUARD exhibited diurnal variations. When Rn concentrations were compared with measurements of temperature (T), barometric pressure, and relative humidity, the correlation (inversely) was highest with T, albeit weakly.

  1. DAC can restore expression of NALP1 to suppress tumor growth in colon cancer.

    PubMed

    Chen, C; Wang, B; Sun, J; Na, H; Chen, Z; Zhu, Z; Yan, L; Ren, S; Zuo, Y

    2015-01-22

    Despite recent progress in the identification of genetic and molecular alternations in colorectal carcinoma, the precise molecular pathogenesis remains unclear. NALP1 (nucleotide-binding oligomerization domain-like receptor family, pyrin domain-containing 1) is a member of the nucleotide-binding oligomerization domain-like receptor family of proteins that are key organization proteins in the inflammasome. It is reported that NALP1 plays a central role in cell apoptosis, pyroptosis, inflammatory reactions and autoimmune diseases. DAC (5-aza-2-deoxycytidine) is an antitumor drug useful to lung cancer, myelodysplastic disorders, myelodysplasia and acute myeloid leukemia. In this study, we examined the expression of NALP1 in human normal and cancerous colon tissues using tissue microarray, western blot and quantitative real-time PCR and we measured the expression of NALP1 in three kinds of colon cancer cell lines and animal models before and after treatment with DAC. Furthermore, we examined the treatment effects of DAC on colon cancer in our animal model. Our data indicate that NALP1 is expressed low in human colorectal tumoral tissues relative to paratumoral tissues and was associated with the survival and tumor metastasis of patients. The expression of NALP1 increased after treatment with DAC both in vitro and in vivo. Furthermore, DAC suppressed the growth of colon cancer and increased lifespan in mouse model. Therefore, we conclude that NALP1 is expressed low in colon cancer and associated with the survival and tumor metastasis of patients, and treatment with DAC can restore NALP1 levels to suppress the growth of colon cancer.

  2. Ambient air concentration of sulfur dioxide affects flight activity in bees

    SciTech Connect

    Ginevan, M.E.; Lane, D.D.; Greenberg, L.

    1980-10-01

    Three long-term (16 to 29 days) low-level (0.14 to 0.28 ppM) sulfur dioxide fumigations showed that exposure tothis gas has deleterious effects on male sweat bees (Lasioglossum zephrum). Although effects on mortality were equivocal, flight activity was definitely reduced. Because flight is necessary for successful mating behavior, the results suggest that sulfur dioxide air pollution could adversely affect this and doubtless other terrestrial insects.

  3. Short-term 222Rn activity concentration changes in underground spaces with limited air exchange with the atmosphere

    NASA Astrophysics Data System (ADS)

    Fijałkowska-Lichwa, L.; Przylibski, T. A.

    2011-04-01

    The authors investigated short-time changes in 222Rn activity concentration occurring yearly in two underground tourist facilities with limited air exchange with the atmosphere. One of them is Niedźwiedzia (Bear) Cave in Kletno, Poland - a natural space equipped with locks ensuring isolation from the atmosphere. The other site is Fluorite Adit in Kletno, a section of a disused uranium mine. This adit is equipped with a mechanical ventilation system, operated periodically outside the opening times (at night). Both sites are situated within the same metamorphic rock complex, at similar altitudes, about 2 km apart. The measurements conducted revealed spring and autumn occurrence of convective air movements. In Bear Cave, this process causes a reduction in 222Rn activity concentration in the daytime, i.e. when tourists, guides and other staff are present in the cave. From the point of view of radiation protection, this is the best situation. For the rest of the year, daily concentrations of 222Rn activity in the cave are very stable. In Fluorite Adit, on the other hand, significant variations in daily 222Rn activity concentrations are recorded almost all year round. These changes are determined by the periods of activity and inactivity of mechanical ventilation. Unfortunately this is inactive in the daytime, which results in the highest values of 222Rn activity concentration at the times when tourists and staff are present in the adit. Slightly lower concentrations of radon in Fluorite Adit are recorded in the winter season, when convective air movements carry a substantial amount of radon out into the atmosphere. The incorrect usage of mechanical ventilation in Fluorite Adit results in the most unfavourable conditions in terms of radiation protection. The staff working in that facility are exposed practically throughout the year to the highest 222Rn activity concentrations, both at work (in the adit) and at home (outside their working hours). Therefore, not very well

  4. Concentration of dimethylnitrosamine in the air of smoke-filled rooms

    SciTech Connect

    Stehlik, G.; Richter, O.; Altmann, H.

    1982-12-01

    In order to evaluate the contribution of volatile nitrosamines from tobacco smoke to indoor air pollution, N-nitroso-dimethylamine (NDMA) and N-nitroso-diethylamine (NDEA) were measured in indoor air under artificial and natural conditions. In controlled experiments under extreme conditions, we found that tobacco smoke-related NDMA levels above 0.07 ng/liter were associated with a highly irritating atmosphere which was scarcely tolerable to those present. In smoke-filled rooms under natural conditions NDMA levels ranged from 0.02 to 0.05 ng/liter except a minimum value of less than 0.01 ng/liter in a restaurant and a maximum of 0.07 ng/liter in a dancing bar. These NDMA levels are thus below comparable values reported by others. The NDMA/NDEA ratios found in air samples taken from some rooms under conditions of everyday life are quite different from those found in sidestream smoke of cigarettes. Irritation was not reported under natural conditions. From the results it is concluded that NDMA levels, measured under real life conditions, are usually not caused by tobacco smoke alone. Evidence for other sources of volatile nitrosamines is discussed.

  5. Pulse shaping for 112 Gbit/s polarization multiplexed 16-QAM signals using a 21 GSa/s DAC.

    PubMed

    Cartledge, John C; Downie, John D; Hurley, Jason E; Karar, Abdullah S; Jiang, Ying; Roberts, Kim

    2011-12-12

    The implications of increasing the symbol rate for a given digital-to-analog converter (DAC) sampling rate are investigated by considering the generation of 112 Gbit/s PM 16-QAM signals (14 Gsym/s) using a 21 GSa/s DAC with 6-bit resolution.

  6. Comparative microarray analysis and pulmonary changes in Brown Norway rats exposed to ovalbumin and concentrated air particulates.

    PubMed

    Heidenfelder, Brooke L; Reif, David M; Harkema, Jack R; Cohen Hubal, Elaine A; Hudgens, Edward E; Bramble, Lori A; Wagner, James G; Morishita, Masako; Keeler, Gerald J; Edwards, Stephen W; Gallagher, Jane E

    2009-03-01

    The interaction between air particulates and genetic susceptibility has been implicated in the pathogenesis of asthma. The overall objective of this study was to determine the effects of inhalation exposure to environmentally relevant concentrated air particulates (CAPs) on the lungs of ovalbumin (ova) sensitized and challenged Brown Norway rats. Changes in gene expression were compared with lung tissue histopathology, morphometry, and biochemical and cellular parameters in bronchoalveolar lavage fluid (BALF). Ova challenge was responsible for the preponderance of gene expression changes, related largely to inflammation. CAPs exposure alone resulted in no significant gene expression changes, but CAPs and ova-exposed rodents exhibited an enhanced effect relative to ova alone with differentially expressed genes primarily related to inflammation and airway remodeling. Gene expression data was consistent with the biochemical and cellular analyses of the BALF, the pulmonary pathology, and morphometric changes when comparing the CAPs-ova group to the air-saline or CAPs-saline group. However, the gene expression data were more sensitive than the BALF cell type and number for assessing the effects of CAPs and ova versus the ova challenge alone. In addition, the gene expression results provided some additional insight into the TGF-beta-mediated molecular processes underlying these changes. The broad-based histopathology and functional genomic analyses demonstrate that exposure to CAPs exacerbates rodents with allergic inflammation induced by an allergen and suggests that asthmatics may be at increased risk for air pollution effects.

  7. Estimation of mean annual effective dose through radon concentration in the water and indoor air of Islamabad and Murree.

    PubMed

    Ali, N; Khan, E U; Akhter, P; Khan, F; Waheed, A

    2010-09-01

    Different samples of water, indoor air and soil gas have been collected from Islamabad (33 degrees 38'N, 73 degrees 09'E, altitude of 1760 ft.), the capital of Pakistan and Murree (33 degrees 53'N, 73 degrees 23'E, altitude of 7323 ft.), lying on a geological fault line and are analysed for the estimation of mean effective dose through radon concentrations by using RAD-7, a solid state alpha-detector. The variation of radon concentration in water, indoor air and soil gas in Islamabad region ranges from 25.90-158.40 kBq m(-3), 43.26-97.04 Bq m(-3) and 17.34-72.52 kBq m(-3), having mean values 88.63 kBq m(-3), 70.67 Bq m(-3) and 45.08 kBq m(-3)(,) respectively. It ranges from 1.64-10.20 kBq m(-3), 18.48-42.08 Bq m(-3) and 0.61-3.89 kBq m(-3) with mean values 4.38 kBq m(-3), 28.63 Bq m(-3) and 1.70 kBq m(-3)(,) respectively in Murree and its surroundings. The total mean annual effective doses from water and indoor air of Islamabad and Murree regions are 2.023 and 0.733 mSv a(-1), respectively. These doses are within the recommended limits of the world organisations.

  8. Dissolved methane concentration profiles and air-sea fluxes from 41°S to 27°N

    NASA Astrophysics Data System (ADS)

    Kelley, Cheryl A.; Jeffrey, Wade H.

    2002-07-01

    Water column samples from a transect cruise from southern Chile through the Panama Canal to the Gulf of Mexico were used to determine dissolved methane depth profiles and air-sea methane fluxes. In the Gulf of Mexico, surface concentrations were approximately 40% supersaturated with respect to the atmosphere, whereas near the equator and in the Peru upwelling region, 10-20% supersaturation generally occurred. These saturation ratios translate into an average flux of methane from the sea surface to the atmosphere of 0.38 μmol m-2 d-1. In addition, water column profiles of dissolved methane indicate that subsurface maxima in dissolved methane concentrations are a consistent feature of the open ocean, except near the equator. At the equator, the subsurface peak at the base of the mixed layer may be bowed down by the Equatorial Undercurrent. The highest methane concentration (12 nM) was observed in the Peru upwelling region.

  9. Prediction of hydrodynamics and chemistry of confined turbulent methane-air frames in a two concentric tube combustor

    NASA Technical Reports Server (NTRS)

    Markatos, N. C.; Spalding, D. B.; Srivatsa, S. K.

    1978-01-01

    A formulation of the governing partial differential equations for fluid flow and reacting chemical species in a two-concentric-tube combustor is presented. A numerical procedure for the solution of the governing differential equations is described and models for chemical-equilibrium and chemical-kinetics calculations are presented. The chemical-equilibrium model is used to characterize the hydrocarbon reactions. The chemical-kinetics model is used to predict the concentrations of the oxides of nitrogen. The combustor considered consists of two coaxial ducts. Concentric streams of gaseous fuel and air enter the inlet duct at one end; the flow then reverses and flows out through the outer duct. Two sample cases with specified inlet and boundary conditions are considered and the results are discussed.

  10. Sources, Concentrations and Risks of Naphthalene in Indoor and Outdoor Air

    PubMed Central

    Batterman, Stuart; Chin, Jo-Yu; Jia, Chunrong; Godwin, Christopher; Parker, Edith; Robins, Thomas; Max, Paul; Lewis, Toby

    2011-01-01

    Naphthalene is a ubiquitous pollutant, and very high concentrations are sometimes encountered indoors when this chemical is used as a pest repellent or deodorant. This study describes the distribution and sources of vapor phase naphthalene concentrations in four communities in southeast Michigan, USA. Outdoors, naphthalene was measured in the communities and at a near-road site. Indoors, naphthalene levels were characterized in 288 suburban and urban homes. The median outdoor concentration was 0.15 µg m−3, and a modest contribution from rush-hour traffic was noted. The median indoor long-term concentration was 0.89 µg m−3, but concentrations were extremely skewed and 14% of homes exceeded 3 µg m−3, the chronic reference concentration for non-cancer effects, 8% exceeded 10 µg m−3, and levels reached 200 µg m−3. The typical individual lifetime cancer risk was about 10−4, and reached 10−2 in some homes. Important sources include naphthalene's use as a pest repellent and deodorant, migration from attached garages, and to lesser extents, cigarette smoke and vehicle emissions. Excessive use as a repellent caused the highest concentrations. Naphthalene presents high risks in a subset of homes, and policies and actions to reduce exposures, e.g., sales bans or restrictions, improved labeling and consumer education, should be considered. PMID:22145682

  11. Concentrations and Risks of p-Dichlorobenzene in Indoor and Outdoor Air

    PubMed Central

    Chin, Jo-Yu; Godwin, Christopher; Jia, Chunrong; Robins, Thomas; Lewis, Toby; Parker, Edith; Max, Paul; Batterman, Stuart

    2012-01-01

    p-Dichlorobenzene (PDCB) is a chlorinated volatile organic compound (VOC) that can be encountered at high concentrations in buildings due to its use as pest repellent and deodorant. This study characterizes PDCB concentrations in four communities in southeast Michigan. The median concentration outside 145 homes was 0.04 µg m−3, and the median concentration inside 287 homes was 0.36 µg m−3. The distribution of indoor concentrations was extremely skewed. For example, 30% of the homes exceeded 0.91 µg m−3, which corresponds to a cancer risk level of 10−5 based on the California unit risk estimate, and 4% of homes exceeded 91 µg m−3, equivalent to a 10−3 risk level. The single highest measurement was 4,100 µg m−3. Estimates of whole house emission rates were largely consistent with chamber test results in the literature. Indoor concentrations that exceed a few µg m−3 indicate use of PDCB products. PDCB concentrations differed among households and the four cities, suggesting the importance of locational, cultural and behavioral factors in the use patterns of this chemical. The high PDCB levels found suggest the need for policies and actions to lower exposures, e.g., sales or use restrictions, improved labeling, and consumer education. PMID:22725685

  12. Final Report for DOE Project: Portal Web Services: Support of DOE SciDAC Collaboratories

    SciTech Connect

    Mary Thomas, PI; Geoffrey Fox, Co-PI; Gannon, D; Pierce, M; Moore, R; Schissel, D; Boisseau, J

    2007-10-01

    Grid portals provide the scientific community with familiar and simplified interfaces to the Grid and Grid services, and it is important to deploy grid portals onto the SciDAC grids and collaboratories. The goal of this project is the research, development and deployment of interoperable portal and web services that can be used on SciDAC National Collaboratory grids. This project has four primary task areas: development of portal systems; management of data collections; DOE science application integration; and development of web and grid services in support of the above activities.

  13. THE CONTRIBUTION OF PARTICLE RESUSPENSION TO INDOOR AND PERSONAL AIR CONCENTRATIONS

    EPA Science Inventory

    An association has been demonstrated between ambient PM concentrations and human morbidity/mortality. However, little is known regarding the most important sources of PM exposure, inter- and intrapersonal variability in exposure, and the relationship between personal exposure a...

  14. Biomonitoring urban air pollution using transplanted lichens: element concentrations across seasons.

    PubMed

    Malaspina, Paola; Tixi, Sara; Brunialti, Giorgio; Frati, Luisa; Paoli, Luca; Giordani, Paolo; Modenesi, Paolo; Loppi, Stefano

    2014-11-01

    We investigated the bioaccumulation of selected trace elements in samples of the lichen Evernia prunastri (L.) Ach. transplanted across two seasons in the urban area of Genoa (NW Italy), which is heavily affected by traffic and industrial pollution. Total concentration of most elements did not exhibit differences between seasons, exceptions being Al and Na, higher in summer, and As, Cd, and Ti, higher in winter. Differences emerged in the initial concentrations of some elements in control samples, and this was accounted for by the use of exposed-to-control (EC) ratios, which allowed interpretation of changes in element concentrations. The study area resulted highly polluted, likely by particulate matter, as suggested also by the higher concentrations of airborne PM10 during winter months. Bioaccumulation of particulate matter seems to be affected by differences in rainfall regimes across seasons, since element solubilization and leaching due to precipitation may vary considerably.

  15. Meteorological adjustment of yearly mean values for air pollutant concentration comparison

    NASA Technical Reports Server (NTRS)

    Sidik, S. M.; Neustadter, H. E.

    1976-01-01

    Using multiple linear regression analysis, models which estimate mean concentrations of Total Suspended Particulate (TSP), sulfur dioxide, and nitrogen dioxide as a function of several meteorologic variables, two rough economic indicators, and a simple trend in time are studied. Meteorologic data were obtained and do not include inversion heights. The goodness of fit of the estimated models is partially reflected by the squared coefficient of multiple correlation which indicates that, at the various sampling stations, the models accounted for about 23 to 47 percent of the total variance of the observed TSP concentrations. If the resulting model equations are used in place of simple overall means of the observed concentrations, there is about a 20 percent improvement in either: (1) predicting mean concentrations for specified meteorological conditions; or (2) adjusting successive yearly averages to allow for comparisons devoid of meteorological effects. An application to source identification is presented using regression coefficients of wind velocity predictor variables.

  16. Work plan for transition of SY-101 hydrogen mitigation test project data acquisition and control system (DACS-1)

    SciTech Connect

    McClees, J.; Truitt, R.W.

    1994-10-12

    The purpose of this effort is to transfer operating and maintenance responsibility for the 241-SY-101 data acquisition and control system (DACS-1) from Los Alamos National Laboratory to Westinghouse Hanford Company. This work plan defines the tasks required for a successful turnover. It identifies DACS-1 transition, deliverables, responsible organizations and individuals, interfaces, cost, and schedule. The transition plan will discuss all required hardware, software, documentation, maintenance, operations, and training for use at Hanford Waste Tank 241-SY-101. The transfer of responsibilities for DACS-1 to WHC is contingent on final approval of applicable Acceptance for Beneficial Use documentation by Waste Tank Operations. The DACS-1 was designed to provide data monitoring, display, and storage for Tank 241-SY-101. The DACS-1 also provides alarm and control of all the hydrogen mitigation testing systems, as well as ancillary systems and equipment (HVAC, UPS, etc.) required to achieve safe and reliable operation of the testing systems in the tank.

  17. Extraction and concentration of vapors from fire debris for forensic purposes: evaluation of the use of Radiello Passive Air Sampler.

    PubMed

    Baechler, S; Comment, S; Delémont, O

    2010-09-15

    The Radiello Passive Air Sampler is one of the latest innovations developed for the sampling of pollutants in the air by passive headspace. It has been reported that its properties allow an enhanced sensitivity, reproducibility and adsorption capacity. It therefore appears to be of interest in the extraction of potential residues of ignitable liquids present in fire debris when arson is suspected. A theoretical approach and several laboratory tests have made it possible to precisely characterize in a forensic perspective the potential of the device in extracting and concentrating the vapors of ignitable liquids found in fire debris. Despite some advantages, the Radiello device appears to be less efficient than traditional axial symmetry samplers.

  18. The Correlation of Radon Concentration with Various Building Attributes at U.S. Air Force Bases

    DTIC Science & Technology

    1992-08-01

    these daughter products that continue to decay giving off radiation which can then lead to the development of lung cancer . The United States Air Force...USAF) is concerned about the increased risk of developing lung cancer by persons exposed to elevated levels of radon in their domiciles and in their...CONOM 0 S * 0 0 a N&NO.)C Nowfum - a w em C mec0- C Mama - 00 4.4 .Q0 0 40 VO O 02ýCt > a MW 0 5 O 0 500 0 ’-ONM > Co S- -W N 00l 0 N 0 O--0 CPe go - Na Wm

  19. Observation of Elevated Air Pollutant Concentrations in a Residential Neighborhood of Los Angeles California Using a Mobile Platform

    PubMed Central

    Hu, Shishan; Fruin, Scott; Kozawa, Kathleen; Mara, Steve; Winer, Arthur M.

    2013-01-01

    We observed elevated air pollutant concentrations, especially of ultrafine particles (UFP), black carbon (BC) and NO, across the residential neighborhood of the Boyle Heights Community (BH) of Los Angeles, California. Using an electric vehicle mobile platform equipped with fast response instruments, real-time air pollutant concentrations were measured in BH in spring and summer of 2008. Pollutant concentrations varied significantly in the two seasons, on different days, and by time of day, with an overall average UFP concentration in the residential areas of ~33 000 cm−3. The averaged UFP, BC, and NO concentrations measured on Soto St, a major surface street in BH, were 57 000 cm−3, 5.1 µg m−3, and 67 ppb, respectively. Concentrations of UFP across the residential areas in BH were nearly uniform spatially, in contrast to other areas in the greater metropolitan area of Los Angeles where UFP concentrations exhibit strong gradients downwind of roadways. We attribute this “UFP cloud” to high traffic volumes, including heavy duty diesel trucks on the freeways which surround and traverse BH, and substantial numbers of high-emitting vehicles (HEVs) on the surface streets traversing BH. Additionally, the high density of stop signs and lights and short block lengths, requiring frequent accelerations of vehicles, may contribute. The data also support a role for photochemical production of UFP in the afternoon. UFP concentration peaks (5 s average) of up to 9 million particles cm−3 were also observed immediately behind HEVs when they accelerated from stop lights in the BH neighborhood and areas immediately adjacent. Although encounters with HEV during mornings accounted for only about 6% and 17% of time spent monitoring residential areas and major surface streets, HEV contributed to about 28% and 53% of total ultrafine particles measured on the route, respectively. The observation of elevated pollutant number concentrations across the Boyle Heights community

  20. Relationship between high concentration of air pollutants and meteorological condition in Nagoya, a coastal city in central Japan

    SciTech Connect

    Mori, Hiroaki; Kitada, Toshihiro

    1996-12-31

    To obtain knowledge for urban and regional planning suitable for the prevention of air pollution, the relationship between the high concentration of air pollutants and the meteorological condition was statistically investigated, using hourly SO{sub 2} and NO{sub x} concentration data measured in Nagoya for one year from April 1985 through March 1986. First, the daily average and maximum concentration of SO{sub 2} and NO{sub x} were calculated. Secondly, the {open_quotes}polluted days{close_quotes} were selected for each of warm and cool periods: the polluted days stand for those in which the concentrations at more than 50% of the monitoring stations of all within the highest thirties. Thirdly, for those selected days the diurnal variations of SO{sub 2}, NO{sub x} and meteorological factors such as wind speed, wind direction and atmospheric stability, were analyzed. Results are as follows. In the warm period, there was a clear difference in meteorological condition between the high-SO{sub 2} and high-NO{sub x} days. The high-SO{sub 2} days appeared mainly in {open_quotes}land and sea breezes{close_quotes} situation (hereafter LSB), which occurs in fine weather with light synoptic pressure gradient. In the days, SO{sub 2} concentration at many observation points showed sharp and clear peak in a day. Namely, the SO{sub 2} concentration reaches its peak value when sea breeze front passes over the observation point, and then decreases rapidly. On the other hand, the high-NO{sub x} concentrations usually occurs in cloudy and rainy days with weak mean wind (hereafter BW, {open_quotes}bad weather{close_quotes}). In these days, NO{sub x} concentration gradually rises to its peak value in the morning, and remains high during daytime. In the cool period, both of the high SO{sub 2} and NO{sub x} concentrations appeared mainly with the BW situation, and sometimes with a fine weather under very weak synoptic-scale pressure gradient conditions.

  1. Observation of elevated air pollutant concentrations in a residential neighborhood of Los Angeles California using a mobile platform

    NASA Astrophysics Data System (ADS)

    Hu, Shishan; Paulson, Suzanne E.; Fruin, Scott; Kozawa, Kathleen; Mara, Steve; Winer, Arthur M.

    2012-05-01

    We observed elevated air pollutant concentrations, especially of ultrafine particles (UFP), black carbon (BC) and NO, across the residential neighborhood of the Boyle Heights Community (BH) of Los Angeles, California. Using an electric vehicle mobile platform equipped with fast response instruments, real-time air pollutant concentrations were measured in BH in spring and summer of 2008. Pollutant concentrations varied significantly in the two seasons, on different days, and by time of day, with an overall average UFP concentration in the residential areas of ∼33 000 cm-3. The averaged UFP, BC, and NO concentrations measured on Soto St, a major surface street in BH, were 57 000 cm-3, 5.1 μg m-3, and 67 ppb, respectively. Concentrations of UFP across the residential areas in BH were nearly uniform spatially, in contrast to other areas in the greater metropolitan area of Los Angeles where UFP concentrations exhibit strong gradients downwind of roadways. We attribute this “UFP cloud” to high traffic volumes, including heavy duty diesel trucks on the freeways which surround and traverse BH, and substantial numbers of high-emitting vehicles (HEVs) on the surface streets traversing BH. Additionally, the high density of stop signs and lights and short block lengths, requiring frequent accelerations of vehicles, may contribute. The data also support a role for photochemical production of UFP in the afternoon. UFP concentration peaks (5 s average) of up to 9 million particles cm-3 were also observed immediately behind HEVs when they accelerated from stop lights in the BH neighborhood and areas immediately adjacent. Although encounters with HEV during mornings accounted for only about 6% and 17% of time spent monitoring residential areas and major surface streets, HEV contributed to about 28% and 53% of total ultrafine particles measured on the route, respectively. The observation of elevated pollutant concentrations across the Boyle Heights community highlights

  2. Observation of Elevated Air Pollutant Concentrations in a Residential Neighborhood of Los Angeles California Using a Mobile Platform.

    PubMed

    Hu, Shishan; Paulson, Suzanne E; Fruin, Scott; Kozawa, Kathleen; Mara, Steve; Winer, Arthur M

    2012-05-01

    We observed elevated air pollutant concentrations, especially of ultrafine particles (UFP), black carbon (BC) and NO, across the residential neighborhood of the Boyle Heights Community (BH) of Los Angeles, California. Using an electric vehicle mobile platform equipped with fast response instruments, real-time air pollutant concentrations were measured in BH in spring and summer of 2008. Pollutant concentrations varied significantly in the two seasons, on different days, and by time of day, with an overall average UFP concentration in the residential areas of ~33 000 cm(-3). The averaged UFP, BC, and NO concentrations measured on Soto St, a major surface street in BH, were 57 000 cm(-3), 5.1 µg m(-3), and 67 ppb, respectively. Concentrations of UFP across the residential areas in BH were nearly uniform spatially, in contrast to other areas in the greater metropolitan area of Los Angeles where UFP concentrations exhibit strong gradients downwind of roadways. We attribute this "UFP cloud" to high traffic volumes, including heavy duty diesel trucks on the freeways which surround and traverse BH, and substantial numbers of high-emitting vehicles (HEVs) on the surface streets traversing BH. Additionally, the high density of stop signs and lights and short block lengths, requiring frequent accelerations of vehicles, may contribute. The data also support a role for photochemical production of UFP in the afternoon. UFP concentration peaks (5 s average) of up to 9 million particles cm(-3) were also observed immediately behind HEVs when they accelerated from stop lights in the BH neighborhood and areas immediately adjacent. Although encounters with HEV during mornings accounted for only about 6% and 17% of time spent monitoring residential areas and major surface streets, HEV contributed to about 28% and 53% of total ultrafine particles measured on the route, respectively. The observation of elevated pollutant number concentrations across the Boyle Heights community

  3. Inter-comparison of air pollutant concentrations in different indoor environments in Hong Kong

    NASA Astrophysics Data System (ADS)

    Lee, Shun-Cheng; Guo, Hai; Li, Wai-Ming; Chan, Lo-Yin

    Indoor air quality in selected indoor environments in Hong Kong such as homes, offices, schools, shopping malls and restaurants were investigated. Average CO 2 levels and total bacteria counts in air-conditioned classrooms, shopping malls and restaurants were comparatively higher than those measured in occupied offices and homes. Elevated CO 2 levels exceeding 1000 ppm and total bacteria counts resulted from high occupancy combined with inadequate ventilation. Average PM 10 levels were usually higher indoors than outdoors in homes, shopping malls and restaurants. The highest indoor PM 10 levels were observed at investigated restaurants due to the presence of cigarette smoking and extensive use of gas stoves for cooking. The restaurants and shopping malls investigated had higher formaldehyde levels than other indoor environments when building material, smoking and internal renovation work were present. Volatile organic compounds (VOCs) in both indoor and outdoor environments mainly resulted from vehicle exhaust emissions. It was observed that interior decoration work and the use of industrial solvents in an indoor environment could significantly increase the indoor levels of VOCs.

  4. Patterns of household concentrations of multiple indoor air pollutants in China.

    PubMed

    He, Gongli; Ying, Bo; Liu, Jiang; Gao, Shirong; Shen, Shaolin; Balakrishnan, Kalpana; Jin, Yinlong; Liu, Fan; Tang, Ning; Shi, Kai; Baris, Enis; Ezzati, Majid

    2005-02-15

    Most previous studies on indoor air pollution from household use of solid fuels have used either indirect proxies for human exposure or measurements of individual pollutants at a single point, as indicators of (exposure to) the mixture of pollutants in solid fuel smoke. A heterogeneous relationship among pollutant-location pairs should be expected because specific fuel-stove technology and combustion and dispersion conditions such as temperature, moisture, and air flow are likely to affect the emissions and dispersion of the various pollutants differently. We report on a study for monitoring multiple pollutants--including respirable particles (RPM), carbon monoxide, sulfur dioxide, fluoride, and arsenic--at four points inside homes that used coal and/or biomass fuels in Guizhou and Shaanxi provinces of China. All pollutants exhibited large variability in emissions and spatial dispersion within and between provinces and were generally poorly correlated. RPM, followed by SO2, was generally higher than common health-based guidelines/standards and provided sufficient resolution for assessing variations within and between households in both provinces. Indoor heating played an important role in the level and spatial patterns of pollution inside homes, possibly to an extent more important than cooking. The findings indicate the need for monitoring of RPM and selected other pollutants in longer-term health studies, with focus on both cooking and living/sleeping areas.

  5. Effects of liquid VOC concentration and salt content on partitioning equilibrium of hydrophilic VOC at air-sweat interface

    NASA Astrophysics Data System (ADS)

    Cheng, Wen-Hsi; Chu, Fu-Sui; Su, Tzy-I.

    Volatile organic compounds (VOCs) must initially be absorbed by sweat on the surface of skin for human VOC dermal exposure. The partitioning equilibrium at the air-sweat interface is given by p=Cg*/C, where pc is the partitioning coefficient, and Cg* is the gaseous concentration in equilibrium with the aqueous VOC concentration ( CL) at a constant water temperature ( Tw). A series of thermodynamic functions of Cg*(C,T) are presented, as well as the values of pc, and the heat of gaseous-liquid phase transfer (Δ Htr) for tested VOCs, including iso-propanol (IPA, CL=12-120 mg L -1) and methyl ethyl ketone (MEK, CL=10-80 mg L -1) to determine the effects of liquid VOC concentration and salt contents of sweat on pc of hydrophilic VOCs. Experimental data reveal that the pc values of IPA and MEK drop as the liquid VOC concentrations increasing from 10 to 120 mg L -1. However, sodium salt content in human sweat (sodium chloride and sodium lactate) induces the effect of salt, indicating the increase in pc. Notably, neither urea nor ammonia in human sweat increase pc. Artificial sweat, consisting of sodium chloride 0.47%, urea 0.05%, ammonia 0.004% and sodium lactate 0.6%, was used to evaluate the increase in the pc values of IPA and MEK. The liquid VOC concentration effect simultaneously develops together with the salt effect on the partition at the interface of air-sweat for hydrophilic VOC solutions. The pc values of IPA for artificial sweat decrease as much as 32.5% as CL increases from 12 to 120 mg L -1 at 300 K, and those of MEK drop by as much as 70.9% as CL increases from 10 to 80 mg L -1 at 300 K. This investigation provides a basis for elucidating the assessment of human dermal exposure to hydrophilic VOCs.

  6. Manganese concentrations in the air of the Montreal (Canada) subway in relation to surface automobile traffic density.

    PubMed

    Boudia, Nacéra; Halley, Renée; Kennedy, Greg; Lambert, Jean; Gareau, Lise; Zayed, Joseph

    2006-07-31

    Methylcyclopentadienyl manganese tricarbonyl (MMT) is an organic derivative of manganese (Mn), used since 1976 in Canadian gasoline as an octane enhancer. Its combustion leads to the emission of Mn particles. Several studies carried out by our research group have established a correlation between atmospheric Mn concentrations and automobile traffic density, suggesting that MMT in gasoline could play a significant role. This study aims to measure Mn concentrations in the air of the underground subway in Montreal (Canada) and to examine the relation with nearby surface automobile traffic density and, by extension, with the use of MMT in gasoline. Three subway stations were chosen for their location in different microenvironments with different traffic densities. Respirable (MnR<5 microm) and total Mn (MnT) were sampled over two weeks, 5 days/week, 12 h/day. For the station located in the lower traffic density area, relatively low levels of MnR and MnT were found, with averages of 0.018 and 0.032 microg/m(3), respectively. These concentrations are within the range of the background levels in Montreal. For the other two stations, the average concentrations of MnR were twice as high and exceeded the US EPA reference concentration of 0.05 microg/m(3). Although there may be several sources of Mn from different components of the subway structure and vehicles, no correlation was found between subway traffic and atmospheric Mn in the subway. Since the air in the underground subway is pumped directly from outside without filtration, our findings strongly suggest that the combustion of MMT in automobiles is an important factor.

  7. The use of wind fields in a land use regression model to predict air pollution concentrations for health exposure studies

    NASA Astrophysics Data System (ADS)

    Arain, M. A.; Blair, R.; Finkelstein, N.; Brook, J. R.; Sahsuvaroglu, T.; Beckerman, B.; Zhang, L.; Jerrett, M.

    A methodology is developed to include wind flow effects in land use regression (LUR) models for predicting nitrogen dioxide (NO 2) concentrations for health exposure studies. NO 2 is widely used in health studies as an indicator of traffic-generated air pollution in urban areas. Incorporation of high-resolution interpolated observed wind direction from a network of 38 weather stations in a LUR model improved NO 2 concentration estimates in densely populated, high traffic and industrial/business areas in Toronto-Hamilton urban airshed (THUA) of Ontario, Canada. These small-area variations in air pollution concentrations that are probably more important for health exposure studies may not be detected by sparse continuous air pollution monitoring network or conventional interpolation methods. Observed wind fields were also compared with wind fields generated by Global Environmental Multiscale-High resolution Model Application Project (GEM-HiMAP) to explore the feasibility of using regional weather forecasting model simulated wind fields in LUR models when observed data are either sparse or not available. While GEM-HiMAP predicted wind fields well at large scales, it was unable to resolve wind flow patterns at smaller scales. These results suggest caution and careful evaluation of regional weather forecasting model simulated wind fields before incorporating into human exposure models for health studies. This study has demonstrated that wind fields may be integrated into the land use regression framework. Such integration has a discernable influence on both the overall model prediction and perhaps more importantly for health effects assessment on the relative spatial distribution of traffic pollution throughout the THUA. Methodology developed in this study may be applied in other large urban areas across the world.

  8. Modelling the effect of air exchange on 222Rn and its progeny concentration in a tunnel atmosphere.

    PubMed

    Perrier, Frédéric; Richon, Patrick; Sabroux, Jean-Christophe

    2005-11-01

    The effect of air exchange on the concentration of 222Rn and its progeny in the atmosphere of the Roselend tunnel, in the French Alps, is estimated using a box modelling scheme. In this scheme, the atmosphere is divided into a small number of well mixed zones, separated by flow restricted interfaces, characterized by their exchange rate. A four-box model, representing the three sections of the tunnel present until 2001 and an adjacent inner room, accounts for the spatial variations of the background 222Rn concentration, and for the time structure of transient bursts observed regularly in this tunnel since 1995. A delay of the order of one day, observed during some transient bursts in the inner room with respect to the end of the tunnel, is accounted for if the bursts are assumed to be mainly generated in the end section of the tunnel, and stored temporarily in the inner room via air exchange. The measured radon concentration is reproduced by this model for an air exchange rate of 1.6x10(-6) s-1 between the room and the tunnel, in a context of a global ventilation rate of 10(-5) s-1 in the tunnel. Gradual onset and decay phases, varying from burst to burst, are also suggested. The equilibrium factor of 222Rn with its progeny, measured in 2002 with values varying from 0.60+/-0.05 to 0.78+/-0.06, is interpreted with a five-box model representing the five sections of the tunnel present after 2001. This model indicates that the equilibrium factor does not provide additional constraints on the air exchange rates, but the value of the deposition rate of the unattached short-lived radon progeny can be inferred, with results varying from 0.2 to 6 h-1 in the various sections. This study illustrates the benefits of a simple modelling tool to evaluate the effect of natural ventilation on 222Rn and its progeny concentration in underground cavities, which is important for radioprotection and for a reliable characterization of signatures of hydrogeological or geodynamical

  9. Modelling deposition and air concentration of reduced nitrogen in Poland and sensitivity to variability in annual meteorology.

    PubMed

    Kryza, Maciej; Dore, Anthony J; Błaś, Marek; Sobik, Mieczysław

    2011-04-01

    The relative contribution of reduced nitrogen to acid and eutrophic deposition in Europe has increased recently as a result of European policies which have been successful in reducing SO(2) and NO(x) emissions but have had smaller impacts on ammonia (NH(3)) emissions. In this paper the Fine Resolution Atmospheric Multi-pollutant Exchange (FRAME) model was used to calculate the spatial patterns of annual average ammonia and ammonium (NH(4)(+)) air concentrations and reduced nitrogen (NH(x)) dry and wet deposition with a 5 km × 5 km grid for years 2002-2005. The modelled air concentrations of NH(3) and dry deposition of NH(x) show similar spatial patterns for all years considered. The largest year to year changes were found for wet deposition, which vary considerably with precipitation amount. The FRAME modelled air concentrations and wet deposition are in reasonable agreement with available measurements (Pearson's correlation coefficients above 0.6 for years 2002-2005), and with spatial patterns of concentrations and deposition of NH(x) reported with the EMEP results, but show larger spatial gradients. The error statistics show that the FRAME model results are in better agreement with measurements if compared with EMEP estimates. The differences in deposition budgets calculated with FRAME and EMEP do not exceed 17% for wet and 6% for dry deposition, with FRAME estimates higher than for EMEP wet deposition for modelled period and lower or equal for dry deposition. The FRAME estimates of wet deposition budget are lower than the measurement-based values reported by the Chief Inspectorate of Environmental Protection of Poland, with the differences by approximately 3%. Up to 93% of dry and 53% of wet deposition of NH(x) in Poland originates from national sources. Over the western part of Poland and mountainous areas in the south, transboundary transport can contribute over 80% of total (dry + wet) NH(x) deposition. The spatial pattern of the relative contribution of

  10. Boundary Layer Model for Air Pollutant Concentrations Due to Highway Traffic

    ERIC Educational Resources Information Center

    Ragland, Kenneth W.; Peirce, J. Jeffrey

    1975-01-01

    A numerical solution of the three-dimensional steady-state diffusion equation for a finite width line source is presented. The wind speed and eddy diffusivity as a function of height above the roadway are obtained. Normalized ground level and elevated concentrations near a highway are obtained for winds perpendicular, parallel, and at 45 degrees.…

  11. The Effects of Scavenging on Waste Methoxyflurane Concentrations in Veterinary Operating Room Air

    DTIC Science & Technology

    1981-01-01

    an increased percentage of fetal anomalies 1 have occurred following exposure of chick eggs to methoxyflurane (28). High subanesthetic concentrations...of methoxyflurane have also caused fetal growth retardation in rats (25). Hepatomegaly and histologic changes of the liver have been demonstrated in

  12. Air ion mobility spectra and concentrations upwind and downwind of overhead AC high voltage power lines

    NASA Astrophysics Data System (ADS)

    Wright, Matthew D.; Buckley, Alison J.; Matthews, James C.; Shallcross, Dudley E.; Henshaw, Denis L.

    2014-10-01

    Corona ions produced by high-voltage power lines (HVPLs) can alter the nearby electrical environment, potentially increasing aerosol charge levels downwind. However, there is a lack of knowledge concerning the concentration and mobility of ions from AC HVPLs and their dispersion away from the line. We present ion concentration and mobility measurements made near AC HVPLs in South-West England. Examples of typical mobility spectra are shown highlighting features commonly observed. Corona was observed during 33 of 46 measurements, at 9 of 11 sites, with positive or ‘bipolar' (both polarities) ion production commonly seen. Ion production usually increases atmospheric concentrations by only a modest amount, but extreme cases can enhance concentration by an order of magnitude or more. A polarity imbalance is required to increase aerosol charge via ion attachment; this was observed on 15 of 24 days when positive corona was observed, but was not seen for negative ions. Ion mobility was higher downwind compared with upwind for both ion polarities, but the increase was not statistically significant. Future work should focus on identifying and characterising ‘heavy-producing' HVPLs, and obtaining results in conditions which may favour negative ion production e.g. high humidity, inclement weather or during nighttime.

  13. Monoterpene emissions and carbonyl compound air concentrations during the blooming period of rape (Brassica napus).

    PubMed

    Müller, Konrad; Pelzing, Matthias; Gnauk, Thomas; Kappe, Anett; Teichmann, Ulrich; Spindler, Gerald; Haferkorn, Sylvia; Jahn, Yvonne; Herrmann, Hartmut

    2002-12-01

    An increasing percentage of agricultural land in Germany is used for oil seed plants. Hence, rape has become an important agricultural plant (in Saxony 1998: 12% of the farmland) in the recent years. During flowering of rape along with intensive radiation and high temperatures, a higher production and emission of biogenic VOC was observed. The emissions of terpenes were determined and more importantly, high concentrations of organic carbonyl compounds were observed during this field experiment. All measurements of interest have been carried out during two selected days with optimal weather conditions. It is found that the origin or the mechanism of formation of different group of compounds had strong influence on the day to day variation of their concentrations. The emission flux of terpenes from flowering rape plants was determined to be 16-32 microg h(-1) m(-2) (30-60 ng h(-1) per g dry plant-540-11080 ng h(-1) per plant), in total. Limonene, alpha-thujene and sabinene were the most important compounds (about 60% of total terpenes). For limonene and sabinene reference emission rates (Ms) and temperature coefficients were determined: beta(limonene) = 0.108 K(-1) and Ms = 14.57 microg h(-1) m(-2) beta(sabinene) = 0.095 K(-1) and Ms = 5.39 microg h(-1) m(-2). The detected carbonyl compound concentrations were unexpectedly high (maximum formaldehyde concentration was 18.1 ppbv and 3.4 ppbv for butyraldehyde) for an open field. Possible reasons for these concentrations are the combination of primary emission from the plants induced by high temperature and high ozone stress, the secondary formation from biogenically and advected anthropogenically emitted VOC at high radiation intensities and furthered by the low wind speeds at this time.

  14. Tunable hybrid plasma decomposition of dilute concentrations of CC14 in air

    SciTech Connect

    Truex, M.J. ); Bromberg, L.; Cohn, D.R.; Koch, M.; Patrick, R.M.; Thomas, P. . Plasma Fusion Center)

    1993-01-01

    At the Department of Energy Hanford site, a large quantity of the industrial solvent carbon tetrachloride (CC14) was used and subsequently disposed of in leaching fields. Efforts under the Volatile Organic Compound - Arid Integrated Demonstration Program (VOC-Arid ID) are directed at vapor extraction of carbon tetrachloride from the ground and its subsequent decomposition in the contaminated humid air stream. We are developing a mobile electron-beam driven plasma reactor for versatile efficient on-site decomposition of CC14 and other VOCs in carrier gases at atmospheric pressure. The decomposition of the VOCs could result in the generation of CO[sub 2], light hydrocarbons, and reactive chlorine compounds. The latter dissolve and/or dissociate in aqueous solutions.

  15. Tunable hybrid plasma decomposition of dilute concentrations of CC14 in air

    SciTech Connect

    Truex, M.J.; Bromberg, L.; Cohn, D.R.; Koch, M.; Patrick, R.M.; Thomas, P.

    1993-01-01

    At the Department of Energy Hanford site, a large quantity of the industrial solvent carbon tetrachloride (CC14) was used and subsequently disposed of in leaching fields. Efforts under the Volatile Organic Compound - Arid Integrated Demonstration Program (VOC-Arid ID) are directed at vapor extraction of carbon tetrachloride from the ground and its subsequent decomposition in the contaminated humid air stream. We are developing a mobile electron-beam driven plasma reactor for versatile efficient on-site decomposition of CC14 and other VOCs in carrier gases at atmospheric pressure. The decomposition of the VOCs could result in the generation of CO{sub 2}, light hydrocarbons, and reactive chlorine compounds. The latter dissolve and/or dissociate in aqueous solutions.

  16. Career Development, Assessment and Counseling: Applications of the Donald E. Super C-DAC Approach.

    ERIC Educational Resources Information Center

    Osborne, W. Larry; And Others

    Career counseling is central to the counseling profession. The Career Development, Assessment, and Counseling (C-DAC) approach to career counseling, which facilitates the career development of people throughout their lives, has received wide attention; an analysis of the theory and research from which this model was derived are examined here. The…

  17. Multibit sigma-delta modulator with reduced sensitivity to DAC nonlinearity

    NASA Technical Reports Server (NTRS)

    Hairapetian, A.; Zhang, Z. X.; Temes, G. C.

    1991-01-01

    A new architecture is presented for a multibit oversampled Sigma-Delta A/D convertor. A novel feedback arrangement is employed to reduce the sensitivity of the overall resolution to the nonlinearity of the multibit DAC. Simulations confirm the improved performance achieved by the proposed structure.

  18. 34 CFR 272.12 - What geographic regions do the DACs serve?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 34 Education 1 2010-07-01 2010-07-01 false What geographic regions do the DACs serve? 272.12 Section 272.12 Education Regulations of the Offices of the Department of Education OFFICE OF ELEMENTARY AND SECONDARY EDUCATION, DEPARTMENT OF EDUCATION DESEGREGATION ASSISTANCE CENTER PROGRAM What Kinds...

  19. National Computational Infrastructure for Lattice Gauge Theory SciDAC-2 Closeout Report Indiana University Component

    SciTech Connect

    Gottlieb, Steven Arthur; DeTar, Carleton; Tousaint, Doug

    2014-07-24

    This is the closeout report for the Indiana University portion of the National Computational Infrastructure for Lattice Gauge Theory project supported by the United States Department of Energy under the SciDAC program. It includes information about activities at Indian University, the University of Arizona, and the University of Utah, as those three universities coordinated their activities.

  20. 241-SY-101 DACS High hydrogen abort limit reduction (SCR 473) acceptance test report

    SciTech Connect

    ERMI, A.M.

    1999-09-09

    The capability of the 241-SY-101 Data Acquisition and Control System (DACS) computer system to provide proper control and monitoring of the 241-SY-101 underground storage tank hydrogen monitoring system utilizing the reduced hydrogen abort limit of 0.69% was systematically evaluated by the performance of ATP HNF-4927. This document reports the results of the ATP.

  1. Performance Engineering Research Institute SciDAC-2 Enabling Technologies Institute Final Report

    SciTech Connect

    Lucas, Robert

    2013-04-20

    Enhancing the performance of SciDAC applications on petascale systems had high priority within DOE SC at the start of the second phase of the SciDAC program, SciDAC-2, as it continues to do so today. Achieving expected levels of performance on high-end computing (HEC) systems is growing ever more challenging due to enormous scale, increasing architectural complexity, and increasing application complexity. To address these challenges, the University of Southern California?s Information Sciences Institute organized the Performance Engineering Research Institute (PERI). PERI implemented a unified, tripartite research plan encompassing: (1) performance modeling and prediction; (2) automatic performance tuning; and (3) performance engineering of high profile applications. Within PERI, USC?s primary research activity was automatic tuning (autotuning) of scientific software. This activity was spurred by the strong user preference for automatic tools and was based on previous successful activities such as ATLAS, which automatically tuned components of the LAPACK linear algebra library, and other recent work on autotuning domain-specific libraries. Our other major component was application engagement, to which we devoted approximately 30% of our effort to work directly with SciDAC-2 applications. This report is a summary of the overall results of the USC PERI effort.

  2. Chloroform uptake by gutta-percha and assessment of its concentration in air during the chloroform-dip technique.

    PubMed

    Margelos, J; Verdelis, K; Eliades, G

    1996-10-01

    The use of chloroform as an adjunct to the practice of endodontics has been a matter of debate. In the present study the chloroform uptake of gutta-percha cones was determined by a gravimetric assay for different times of chloroform dip. In conjunction with an assessment of the amount of gutta-percha dissolved during dip, this provided an estimate of the amount of chloroform that patients are exposed to in clinical conditions. An assay was also performed of the chloroform concentration in the air in a dental office. Chloroform uptake was shown to increase with an increasing dipping time. There also seems to be a difference in this uptake between pure chloroform and a chloroform preparation with colophonium. The concentration levels of chloroform evaporated during the practice of chloroform dip within a dental office do not exceed the safety limits.

  3. Reduction of CO 2 concentration in a zinc/air battery by absorption in a rotating packed bed

    NASA Astrophysics Data System (ADS)

    Cheng, Hsu-Hsiang; Tan, Chung-Sung

    The reduction of CO 2 concentration in a gas stream containing 500 ppm of CO 2 by a technique combining chemical absorption with Higee (high gravity) was investigated in this study. Using a 2.0 L aqueous amine-based solution to treat the feed gas with a flow rate which varied from 12.9 to 20.6 L min -1, piperazine (PZ) was found to be more effective than 2-(2-aminoethylamino) ethanol (AEEA) and monoethanolamine (MEA) for reducing the CO 2 concentration to a level below 20 ppm. The effects of temperature, rotating speed, amine solution flow rate, and gas flow rate on the removal efficiency of CO 2 were systematically examined. The results indicated that the proposed compact device could effectively reduce CO 2 to a level below 20 ppm, as required by a zinc/air battery, for a long period of time using PZ and its mixture with AEEA and MEA as the absorbents.

  4. Particle-phase concentrations of polycyclic aromatic hydrocarbons in ambient air of rural residential areas in southern Germany

    PubMed Central

    Baumbach, Günter; Kuch, Bertram; Scheffknecht, Günter

    2010-01-01

    An important source of polycyclic aromatic hydrocarbons (PAHs) in residential areas, particularly in the winter season, is the burning process when wood is used for domestic heating. The target of this study was to investigate the particle-phase PAH composition of ambient samples in order to assess the influence of wood combustion on air quality in residential areas. PM10 samples (particulate matter <10 μm) were collected during two winter seasons at two rural residential areas near Stuttgart in Germany. Samples were extracted using toluene in an ultrasonic bath and subsequently analysed by gas chromatography–mass spectrometry. Twenty-one PAH compounds were detected and quantified. The PAH fingerprints of different wood combustion emissions were found in significant amounts in ambient samples and high correlations between total PAHs and other wood smoke tracers were found, indicating the dominant influence of wood combustion on air quality in residential areas. Carcinogenic PAHs were detected in high concentrations and contributed 49% of the total PAHs in the ambient air. To assess the health risk, we investigated the exposure profile of individual PAHs. The findings suggest that attention should be focused on using the best combustion technology available to reduce emissions from wood-fired heating during the winter in residential areas. PMID:20495599

  5. Influence of trans-boundary biomass burning impacted air masses on submicron particle number concentrations and size distributions

    NASA Astrophysics Data System (ADS)

    Betha, Raghu; Zhang, Zhe; Balasubramanian, Rajasekhar

    2014-08-01

    Submicron particle number concentration (PNC) and particle size distribution (PSD) in the size range of 5.6-560 nm were investigated in Singapore from 27 June 2009 through 6 September 2009. Slightly hazy conditions lasted in Singapore from 6 to 10 August. Backward air trajectories indicated that the haze was due to the transport of biomass burning impacted air masses originating from wild forest and peat fires in Sumatra, Indonesia. Three distinct peaks in the morning (08:00-10:00), afternoon (13:00-15:00) and evening (16:00-20:00) were observed on a typical normal day. However, during the haze period no distinct morning and afternoon peaks were observed and the PNC (39,775 ± 3741 cm-3) increased by 1.5 times when compared to that during non-haze periods (26,462 ± 6017). The morning and afternoon peaks on the normal day were associated with the local rush hour traffic while the afternoon peak was induced by new particle formation (NPF). Diurnal profiles of PNCs and PSDs showed that primary particle peak diameters were large during the haze (60 nm) period when compared to that during the non-haze period (45.3 nm). NPF events observed in the afternoon period on normal days were suppressed during the haze periods due to heavy particle loading in atmosphere caused by biomass burning impacted air masses.

  6. Intra-urban spatial variability in wintertime street-level concentrations of multiple combustion-related air pollutants: the New York City Community Air Survey (NYCCAS).

    PubMed

    Clougherty, Jane E; Kheirbek, Iyad; Eisl, Holger M; Ross, Zev; Pezeshki, Grant; Gorczynski, John E; Johnson, Sarah; Markowitz, Steven; Kass, Daniel; Matte, Thomas

    2013-01-01

    Although intra-urban air pollution differs by season, few monitoring networks provide adequate geographic density and year-round coverage to fully characterize seasonal patterns. Here, we report winter intra-urban monitoring and land-use regression (LUR) results from the New York City Community Air Survey (NYCCAS). Two-week integrated samples of fine particles (PM(2.5)), black carbon (BC), nitrogen oxides (NO(x)) and sulfur dioxide (SO(2)) were collected at 155 city-wide street-level locations during winter 2008-2009. Sites were selected using stratified random sampling, randomized across sampling sessions to minimize spatio-temporal confounding. LUR was used to identify GIS-based source indicators associated with higher concentrations. Prediction surfaces were produced using kriging with external drift. Each pollutant varied twofold or more across sites, with higher concentrations near midtown Manhattan. All pollutants were positively correlated, particularly PM(2.5) and BC (Spearman's r=0.84). Density of oil-burning boilers, total and truck traffic density, and temporality explained 84% of PM(2.5) variation. Densities of total traffic, truck traffic, oil-burning boilers and industrial space, with temporality, explained 65% of BC variation. Temporality, built space, bus route location, and traffic density described 67% of nitrogen dioxide variation. Residual oil-burning units, nighttime population and temporality explained 77% of SO(2) variation. Spatial variation in combustion-related pollutants in New York City was strongly associated with oil-burning and traffic density. Chronic exposure disparities and unique local sources can be identified through year-round saturation monitoring.

  7. Low air exchange rate causes high indoor radon concentration in energy-efficient buildings.

    PubMed

    Vasilyev, A V; Yarmoshenko, I V; Zhukovsky, M V

    2015-06-01

    Since 1995, requirements on energy-efficient building construction were established in Russian Building Codes. In the course of time, utilisation of such technologies became prevailing, especially in multi-storey building construction. According to the results of radon survey in buildings constructed meeting new requirements on energy efficiency, radon concentration exceeds the average level in early-constructed buildings. Preponderance of the diffusion mechanism of radon entry in modern multi-storey buildings has been experimentally established. The experimental technique of the assessment of ventilation rate in dwellings under real conditions was developed. Based on estimates of average ventilation rate, it was approved that measures to increase energy efficiency lead to reduction in ventilation rate and accumulation of higher radon concentrations indoors. Obtained ventilation rate values have to be considered as extremely low.

  8. The influence of air-suspended particulate concentration on the incidence of suicide attempts and exacerbation of schizophrenia

    NASA Astrophysics Data System (ADS)

    Yackerson, Naomy S.; Zilberman, Arkadi; Todder, Doron; Kaplan, Zeev

    2014-01-01

    The main objective of this study was to evaluate the role of the concentration of solid air-suspended particles (SSP) in the incidence of mental disorders. The study is based on 1,871 cases, registered in the Beer-Sheva Mental Health Center (BS-MHC) at Ben-Gurion University (Israel) during a 16-month period from 2001 to 2002; 1,445 persons were hospitalized due to exacerbation of schizophrenia (ICD-10: F20-F29) and 426 after committing a suicide attempt using a variety of means as coded in the ICD-10 (ICD-10: X60-X84). Pearson and Spearman test correlations were used; the statistical significance was tested at p < 0.1. A significant correlation between variations of SSP number concentration ( N C ) during eastern desert wind during early morning hours and number of suicide attempts, N SU , was found ( ρ > 0.3, p < 0.05), whereas correlation between N C and N SU during western air streams (sea breeze) was not observed ( p > 0.2). A trend towards positive correlation ( ρ > 0.2, p < 0.1) between the N C and number of persons with exacerbation of schizophrenia as manifested in psychotic attack ( N PS ) in periods with dominant eastern winds (4-9 am, local time) has been observed, while in the afternoon and evening hours (1-8 pm local time) with dominant western winds, N C and N PS are not correlated (p > 0.1). Obviously, concentration of SSP is not the one and only parameter of air pollution state determining meteorological-biological impact, involving incidence of mental disorders, although its role can scarcely be overstated. However, since it is one of the simplest measured parameters, it could be widely used and helpful in the daily struggle for human life comfort in semi-arid areas as well as urban and industrial surroundings, where air pollution reaches crucial values. This study may permit determination of the limits for different external factors, which do not overcome threshold values (without provoking avalanche situations), to single out the group of

  9. Influence of road traffic, residential heating and meteorological conditions on PM10 concentrations during air pollution critical episodes.

    PubMed

    Gualtieri, Giovanni; Toscano, Piero; Crisci, Alfonso; Di Lonardo, Sara; Tartaglia, Mario; Vagnoli, Carolina; Zaldei, Alessandro; Gioli, Beniamino

    2015-12-01

    The importance of road traffic, residential heating and meteorological conditions as major drivers of urban PM10 concentrations during air pollution critical episodes has been assessed in the city of Florence (Italy) during the winter season. The most significant meteorological variables (wind speed and atmospheric stability) explained 80.5-85.5% of PM10 concentrations variance, while a marginal role was played by major emission sources such as residential heating (12.1%) and road traffic (5.7%). The persistence of low wind speeds and unstable atmospheric conditions was the leading factor controlling PM10 during critical episodes. A specific PM10 critical episode was analysed, following a snowstorm that caused a "natural" scenario of 2-day dramatic road traffic abatement (-43%), and a massive (up to +48%) and persistent (8 consecutive days) increase in residential heating use. Even with such a strong variability in local PM10 emissions, the role of meteorological conditions was prominent, revealing that short-term traffic restrictions are insufficient countermeasures to reduce the health impacts and risks of PM10 critical episodes, while efforts should be made to anticipate those measures by linking them with air quality and weather forecasts.

  10. Concentrations, Trends, and Air-Water Exchange of PAHs and PBDEs Derived from Passive Samplers in Lake Superior in 2011.

    PubMed

    Ruge, Zoe; Muir, Derek; Helm, Paul; Lohmann, Rainer

    2015-12-01

    Polycyclic aromatic hydrocarbons (PAHs) and polybrominated diphenylethers (PBDEs) are both currently released into the environment from anthropogenic activity. Both are hence primarily associated with populated or industrial areas, although wildfires can be an important source of PAHs, as well. Polyethylene passive samplers (PEs) were simultaneously deployed in surface water and near surface atmosphere to determine spatial trends and air-water gaseous exchange of 21 PAHs and 11 PBDEs at 19 sites across Lake Superior in 2011. Surface water and atmospheric PAH concentrations were greatest at urban sites (up to 65 ng L(-1) and 140 ng m(-3), respectively, averaged from June to October). Near populated regions, PAHs displayed net air-to-water deposition, but were near equilibrium off-shore. Retene, probably depositing following major wildfires in the region, dominated dissolved PAH concentrations at most Lake Superior sites. Atmospheric and dissolved PBDEs were greatest near urban and populated sites (up to 6.8 pg L(-1) and 15 pg m(-3), respectively, averaged from June to October), dominated by BDE-47. At most coastal sites, there was net gaseous deposition of BDE-47, with less brominated congeners contributing to Sault Ste. Marie and eastern open lake fluxes. Conversely, the central open lake and Eagle Harbor sites generally displayed volatilization of PBDEs into the atmosphere, mainly BDE-47.

  11. A Procedure for Inter-Comparing the Skill of Regional-Scale Air Quality Model Simulations of Daily Maximum 8-Hour Ozone Concentrations

    EPA Science Inventory

    An operational model evaluation procedure is described to quantitatively assess the relative skill among several regionalscale air quality models simulating various percentiles of the cumulative frequency distribution of observed daily maximum 8-h ozone concentrations. Bootstrap ...

  12. Mercury concentrations in air during the Phase I remediation of Lower East Fork Poplar Creek floodplain at the Oak Ridge Y-12 Plant, Oak Ridge, Tennessee

    SciTech Connect

    Barnett, M.O.; Owens, J.G.; Lindberg, S.E.; Turner, R.R.

    1997-01-01

    During the Phase I remediation of Lower East Fork Poplar Creek (LEFPC), the mercury concentration in air was monitored continuously at a nearby off-site location. The purpose of the monitoring was to ensure that the remediation did not adversely affect the off-site concentration of mercury in air. The concentrations of mercury in air did increase during the remediation. However, based on the results of a previous study, this increase was caused by the increase in sunlight intensity and temperature during remediation, which occurred in the summer months. In any case, all concentrations measured before, during, and after remediation were well below the standard of 300 ng/m{sup 3} recommended for continuous exposure to mercury in air.

  13. Increasing concentrations of dichloromethane, CH2Cl2, inferred from CARIBIC air samples collected 1998-2012

    NASA Astrophysics Data System (ADS)

    Leedham Elvidge, E. C.; Oram, D. E.; Laube, J. C.; Baker, A. K.; Montzka, S. A.; Humphrey, S.; O'Sullivan, D. A.; Brenninkmeijer, C. A. M.

    2015-02-01

    Atmospheric concentrations of dichloromethane, CH2Cl2, a regulated toxic air pollutant and minor contributor to stratospheric ozone depletion, were reported to have peaked around 1990 and to be declining in the early part of the 21st century. Recent observations suggest this trend has reversed and that CH2Cl2 is once again increasing in the atmosphere. Despite the importance of ongoing monitoring and reporting of atmospheric CH2Cl2, no time series has been discussed in detail since 2006. The CARIBIC project (Civil Aircraft for the Regular Investigation of the atmosphere Based on an Instrument Container) has analysed the halocarbon content of whole-air samples collected at altitudes of between ~ 10-12 km via a custom-built container installed on commercial passenger aircraft since 1998, providing a long-term record of CH2Cl2 observations. In this paper we present this unique CH2Cl2 time series, discussing key flight routes which have been used at various times over the past 15 years. Between 1998 and 2012 increases were seen in all northern hemispheric regions and at different altitudes, ranging from ~ 7-10 ppt in background air to ~ 13-15 ppt in regions with stronger emissions (equating to a 38-69% increase). Of particular interest is the rising importance of India as a source of atmospheric CH2Cl2: based on CARIBIC data we provide regional emission estimates for the Indian subcontinent and show that regional emissions have increased from 3-14 Gg yr-1 (1998-2000) to 16-25 Gg yr-1 (2008). Potential causes of the increasing atmospheric burden of CH2Cl2 are discussed. One possible source is the increased use of CH2Cl2 as a feedstock for the production of HFC-32, a chemical used predominantly as a replacement for ozone-depleting substances in a variety of applications including air conditioners and refrigeration.

  14. Manganese concentrations in the soil and air in the vicinity of a closed manganese alloy production plant.

    PubMed

    Boudissa, Soraya M; Lambert, Jean; Müller, Caroline; Kennedy, Greg; Gareau, Lise; Zayed, Joseph

    2006-05-15

    In Montreal (Canada), the mean annual atmospheric Mn concentrations between 1981 and 1990 were stable, followed by a decrease of almost 50% from 1990 to 1992. The reason for such a decrease in Mn is probably the shutdown of a large manganese alloy production plant in Beauharnois, approximately 25 km from Montreal. The objective of this study is to assess the level of air and soil contamination by Mn in the vicinity of this ferroalloy plant more than 10 years after its closure. Air and soil were sampled over 5 days at two and three sites, respectively. Site 1 was located 10 m NE of the closed plant, in the direction of the prevailing SW-NE winds. Sites 2 and 3 were at 50 and 800 m SE from the plant. Air samples were collected in order to determine total (MnT) and respirable (MnR). Soil samples were taken in the surface and subsurface strata. The results show that site 1 is extremely polluted with a mean Mn concentration in surface strata of 2,66,000+/-45,000 ppm and 2,83,000+/-23,000 ppm in the subsurface strata, while the average MnT and MnR are 21.9+/-13.7 and 3.5+/-3.9 microg/m(3), respectively. The explanation for this contamination is direct deposition on the soil of solid Mn-rich residue and atmospheric erosion of Mn particles. The situation should be remediated by the public authority with high priority.

  15. Concentrations and changes of chemical elements in aerosol particulate matter as indicators of air quality in Riyadh City, Saudi Arabia

    NASA Astrophysics Data System (ADS)

    Rushdi, A. I.; Al-Mutlaq, K. F.; Simoneit, B. R.

    2010-12-01

    : Samples of air particulate matter (PM) were collected for the determination of chemical elements from June 2006 to May 2007. PM samples were taken in two size modes (PM2.5 and PM10) using MiniVolume air samplers on rooftops of various buildings (15-25 m above ground) in the city of Riyadh. The samples were subjected to XRF analysis to determine both major (Na, Mg, Al, K, Ca, Si, P, S and Fe) and trace elements (Mn, Ni, Cu, Zn, and Ba). The results show that the concentrations of both were higher in PM10 compared to PM2.5 indicating that the major source of the atmospheric PM was local dust. Furthermore, the spatial distribution of high concentrations of PM was in the south and southeast of the city and the lowest was found in the center and north eastern part of the city. This spatial PM distribution was attributed different factors such as wind direction and velocity, existence of cement factories in the southeast of the city, the presence of buildings and trees, and paved streets in the city center that reduce the amount of dust resuspended into the atmosphere. The air quality of the city was found to range from moderate to highly unhealthy for PM2.5 and from good to highly unhealthy for PM10. The enrichment factors for the measured elements were examined and revealed two groups based on their regional distribution. The first group showed no significant spatial changes indicating it has a common source throughout the sampling grid. The second group (mainly S and Ni) showed significant changes as expected from anthropogenic inputs. The S is possibly a combination of a mineralogical (CaSO4) and fossil fuel combustion origin. The source of Ni is probably in emissions from fossil fuel combustion.

  16. A high performance DAC /DDS daughter module for the RHIC LLRF platform

    SciTech Connect

    Hayes, T.; Harvey, M.; Narayan, G.; Severino, F.; Smith, K.S.; Yuan, S.

    2011-03-28

    The RHIC LLRF upgrade is a flexible, modular system. Output signals are generated by a custom designed XMC card with 4 high speed digital to analog (DAC) converters interfaced to a high performance field programmable gate array (FPGA). This paper discusses the hardware details of the XMC DAC board as well as the implementation of a low noise rf synthesizer with digital IQ modulation. This synthesizer also provides injection phase cogging and frequency hop rebucketing capabilities. A new modular RHIC LLRF system was recently designed and commissioned based on custom designed XMC cards. As part of that effort a high speed, four channel DAC board was designed. The board uses Maxim MAX5891 16 bit DACs with a maximum update rate of 600 Msps. Since this module is intended to be used for many different systems throughout the Collider Accelerator complex, it was designed to be as generic as possible. One major application of this DAC card is to implement digital synthesizers to provide drive signals to the various cavities at RHIC. Since RHIC is a storage ring with stores that typically last many hours, extremely low RF noise is a critical requirement. Synchrotron frequencies at RHIC range from a few hertz to several hundred hertz depending on the species and point in the acceleration cycle so close in phase noise is a major concern. The RHIC LLRF system uses the Update Link, a deterministic, high speed data link that broadcasts the revolution frequency and the synchronous phase angle. The digital synthesizers use this data to generate a properly phased analog drive signal. The synthesizers must also provide smooth phase shifts for cogging and support frequency shift rebucketing. One additional feature implemented in the FPGA is a digital waveform generator (WFG) that generates I and Q data pairs based on a user selected amplitude and phase profile as a function of time.

  17. The 1996 Paso del Norte Ozone Study: analysis of meteorological and air quality data that influence local ozone concentrations.

    PubMed

    MacDonal, C P; Roberts, P T; Main, H H; Dye, T S; Coe, D L; Yarbrough, J

    2001-08-10

    The 1996 Paso del Norte Ozone Study and subsequent data analyses were implemented to develop an understanding of the chemical and physical processes which lead to high concentrations of ozone in the Paso del Norte study area which includes El Paso County, Texas, Sunland Park, New Mexico, and Ciudad Juárez, Mexico. Both the data and data analysis results are being used to support photochemical grid modeling. El Paso County and Sunland Park fail to meet the National Ambient Air Quality Standard (NAAQS) for ozone, and neighboring Ciudad Juárez fails to meet the Mexican ambient standard for ozone. This paper summarizes the measurement campaigns of the 1996 Paso del Norte Ozone Study and the findings and conclusions that arose from subsequent data analyses. Data analyses showed that high ozone concentrations resulted from a combination of conditions, including high surface temperatures, strong sunlight with few clouds, light surface winds and high concentrations of ozone precursors at ground level in the morning, and slow convective boundary layer (CBL) growth. Synoptic-scale meteorological conditions observed during high ozone episodes included an aloft high-pressure system and aloft warming. Aloft carryover of ozone and ozone precursors did not significantly contribute to high concentrations of ozone at the surface.

  18. Selective Concentration of Ultra-trace Acetone in the Air by Cryogenic Temperature Programmed Desorption (cryo-TPD).

    PubMed

    Suzuki, Taku T; Sakaguchi, Isao

    2016-01-01

    A gas analytical technique with compact size, low cost, sufficient sensitivity, and excellent reproducibility is required in many fields including exhaled breath analysis for medical monitoring. In the present study, we examined selective acetone concentration by quench condensation at cryogenic temperature followed by temperature programmed desorption (cryogenic temperature programmed desorption (cryo-TPD)) for possible applications to breath analysis for medical monitoring. The essence of cryo-TPD is rough mass selection by thermal desorption followed by quantification of certain species using mass spectrometry. The performance of cryo-TPD was investigated in the acetone concentration range below 1 × 10(-6) volume fraction (1 ppmv). It was found that acetone is selectively quench-condensed on a tungsten substrate at 50 K without the major components of air, such as N2 and O2. The concentrated acetone gas was obtained by the following thermal desorption at around 151 K. Under conditions of condensation for 1 min and pressure of 1 × 10(-2) Pa, the lowest limit of detection reached well below 10 × 10(-9) volume fraction (10 ppbv). The relationship between the cetone intensity of cryo-TPD and the acetone concentration in the gas was almost linear in the ppbv range. The separation of acetone and propanal using the fragmentation pattern, which have almost the identical molecular mass, was also demonstrated in the present study.

  19. Dynamics of carbon dioxide concentrations in the air and its effect on the cognitive ability of school students

    NASA Astrophysics Data System (ADS)

    Sidorin, D. I.

    2015-12-01

    The carbon dioxide (CO2) production intensity by a secondary school student is studied using a nondispersive infrared CO2 logger for different conditions: relaxation, mental stress, and physical stress. CO2 production measured for mental stress is 24% higher than that for relaxation, while CO2 production for physical stress is more than 2.5 times higher than relaxation levels. Dynamics of CO2 concentration in the classroom air is measured for a typical school building. It is shown that even when the classroom is ventilated between classes, CO2 concentration exceeds 2100 parts per million (ppm), which is significantly higher than the recommended limits defined in developed countries. The ability of seventh-grade school students to perform tasks requiring mental concentration is tested under different CO2 concentration conditions (below 1000 ppm and above 2000 ppm). Five-letter word anagrams are used as test tasks. Statistical analysis of the test results revealed a significant reduction in the number of provided correct answers and an increase in the number of errors when CO2 levels exceeded 2000 ppm.

  20. Inverse modeling of Asian (222)Rn flux using surface air (222)Rn concentration.

    PubMed

    Hirao, Shigekazu; Yamazawa, Hiromi; Moriizumi, Jun

    2010-11-01

    When used with an atmospheric transport model, the (222)Rn flux distribution estimated in our previous study using soil transport theory caused underestimation of atmospheric (222)Rn concentrations as compared with measurements in East Asia. In this study, we applied a Bayesian synthesis inverse method to produce revised estimates of the annual (222)Rn flux density in Asia by using atmospheric (222)Rn concentrations measured at seven sites in East Asia. The Bayesian synthesis inverse method requires a prior estimate of the flux distribution and its uncertainties. The atmospheric transport model MM5/HIRAT and our previous estimate of the (222)Rn flux distribution as the prior value were used to generate new flux estimates for the eastern half of the Eurasian continent dividing into 10 regions. The (222)Rn flux densities estimated using the Bayesian inversion technique were generally higher than the prior flux densities. The area-weighted average (222)Rn flux density for Asia was estimated to be 33.0 mBq m(-2) s(-1), which is substantially higher than the prior value (16.7 mBq m(-2) s(-1)). The estimated (222)Rn flux densities decrease with increasing latitude as follows: Southeast Asia (36.7 mBq m(-2) s(-1)); East Asia (28.6 mBq m(-2) s(-1)) including China, Korean Peninsula and Japan; and Siberia (14.1 mBq m(-2) s(-1)). Increase of the newly estimated fluxes in Southeast Asia, China, Japan, and the southern part of Eastern Siberia from the prior ones contributed most significantly to improved agreement of the model-calculated concentrations with the atmospheric measurements. The sensitivity analysis of prior flux errors and effects of locally exhaled (222)Rn showed that the estimated fluxes in Northern and Central China, Korea, Japan, and the southern part of Eastern Siberia were robust, but that in Central Asia had a large uncertainty.

  1. Photoinduced nucleation: a novel tool for detecting molecules in air at ultra-low concentrations

    DOEpatents

    Katz, Joseph L.; Lihavainen, Heikki; Rudek, Markus M.; Salter, Brian C.

    2002-01-01

    A method and apparatus for determining the presence of molecules in a gas at concentrations of less than about 100 ppb. Light having wavelengths in the range from about 200 nm to about 350 nm is used to illuminate a flowing sample of the gas causing the molecules if present to form clusters. A mixture of the illuminated gas and a vapor is cooled until the vapor is supersaturated so that there is a small rate of homogeneous nucleation. The supersaturated vapor condenses on the clusters thus causing the clusters to grow to a size sufficient to be counted by light scattering and then the clusters are counted.

  2. Concentrations and co-occurrence correlations of 88 volatile organic compounds (VOCs) in the ambient air of 13 semi-rural to urban locations in the United States

    USGS Publications Warehouse

    Pankow, J.F.; Luo, W.; Bender, D.A.; Isabelle, L.M.; Hollingsworth, J.S.; Chen, C.; Asher, W.E.; Zogorski, J.S.

    2003-01-01

    The ambient air concentrations of 88 volatile organic compounds were determined in samples taken at 13 semi-rural to urban locations in Maine, Massachusetts, New Jersey, Pennsylvania, Ohio, Illinois, Louisiana, and California. The sampling periods ranged from 7 to 29 months, yielding a large data set with a total of 23,191 individual air concentration values, some of which were designated "ND" (not detected). For each compound at each sampling site, the air concentrations (ca, ppbV) are reported in terms of means, medians, and means of the detected values. The analytical method utilized adsorption/thermal desorption with air-sampling cartridges. The analytes included numerous halogenated alkanes, halogenated alkenes, ethers, alcohols, nitriles, esters, ketones, aromatics, a disulfide, and a furan. At some sites, the air concentrations of the gasoline-related aromatic compounds and the gasoline additive methyl tert-butyl ether were seasonally dependent, with concentrations that maximized in the winter. For each site studied here, the concentrations of some compounds were highly correlated one with another (e.g., the BTEX group (benzene, toluene, ethylbenzene, and the xylenes). Other aromatic compounds were also all generally correlated with one another, while the concentrations of other compound pairs were not correlated (e.g., benzene was not correlated with CFC-12). The concentrations found for the BTEX group were generally lower than the values that have been previously reported for urbanized and industrialized areas of other nations. ?? 2003 Elsevier Ltd. All rights reserved.

  3. Measurement of Absolute Hydroxyl Radical Concentration in Lean Fuel-Air Mixtures Excited by Nanosecond Pulsed Discharge.

    NASA Astrophysics Data System (ADS)

    Yin, Z.; Lempert, W. R.; Adamovich, I. V.

    2013-06-01

    The focus in plasma assisted combustion research has been on the evaluation of conventional plasma/combustion mechanisms in predicting oxidation and ignition processes initiated and/or sustained by non-equilibrium, nanosecond discharges. Accurate quantitative data such as temperature and species concentration are needed for assessing and improving numerical modeling. As an important intermediate species, the concentration of hydroxyl radical (OH) is very sensitive to the combustion environment (e.g., temperature, equivalence ratio), and therefore is of great interest to kinetic study. In this work, Laser-Induced Fluorescence (LIF) was used for time-resolved temperature and OH number density measurements in lean H_2-, CH_4-, C_2H_4-, and C_3H_8- air mixtures in a plasma flow reactor inside a tube furnace. The premixed fuel-air flow in the reactor, initially at T_0=500 K and P=100 torr, was excited by a burst of repetitive nanosecond electric pulses in a dielectric-barrier plane-to-plane geometry (˜28 kV peak voltage and ˜5 nsec pulse width, estimated 1.25 mJ/pulse coupled energy). Laser was timed to probe after the discharge burst was over to avoid strong plasma emission interference. Relative fluorescence signal was put on an absolute scale by calibrating against Rayleigh scattering signal in the same flow reactor. Experimental results were compared to predictions from a 0-D plasma/combustion chemistry model employing several well-established combustion mechanisms. 2-D temperature and OH concentration distributions in the discharge volume were obtained by planar LIF and was used to quantitatively evaluate plasma uniformity in the reactor. These results were used to determine the validity of the 0-D model. thanks

  4. Subsurface occurrence and potential source areas of chlorinated ethenes identified using concentrations and concentration ratios, Air Force Plant 4 and Naval Air Station-Joint Reserve Base Carswell Field, Fort Worth, Texas

    USGS Publications Warehouse

    Garcia, C. Amanda

    2005-01-01

    The U.S. Geological Survey, in cooperation with the U.S. Air Force Aeronautical Systems Center, Environmental Management Directorate, conducted a study during 2003-05 to characterize the subsurface occurrence and identify potential source areas of the volatile organic compounds classified as chlorinated ethenes at U.S. Air Force Plant 4 (AFP4) and adjacent Naval Air Station-Joint Reserve Base Carswell Field (NAS-JRB) at Fort Worth, Texas. The solubilized chlorinated ethenes detected in the alluvial aquifer originated as either released solvents (tetrachloroethene [PCE], trichloroethene [TCE], and trans-1,2-dichloroethene [trans-DCE]) or degradation products of the released solvents (TCE, cis-1,2-dichloroethene [cis-DCE], and trans-DCE). The combined influences of topographic- and bedrock-surface configurations result in a water table that generally slopes away from a ground-water divide approximately coincident with bedrock highs and the 1-mile-long aircraft assembly building at AFP4. Highest TCE concentrations (10,000 to 920,000 micrograms per liter) occur near Building 181, west of Building 12, and at landfill 3. Highest PCE concentrations (500 to 920 micrograms per liter) occur near Buildings 4 and 5. Highest cis-DCE concentrations (5,000 to 710,000 micrograms per liter) occur at landfill 3. Highest trans-DCE concentrations (1,000 to 1,700 micrograms per liter) occur just south of Building 181 and at landfill 3. Ratios of parent-compound to daughter-product concentrations that increase in relatively short distances (tens to 100s of feet) along downgradient ground-water flow paths can indicate a contributing source in the vicinity of the increase. Largest increases in ratio of PCE to TCE concentrations are three orders of magnitude from 0.01 to 2.7 and 7.1 between nearby wells in the northeastern part of NAS-JRB. In the northern part of NAS-JRB, the largest increases in TCE to total DCE concentration ratios relative to ratios at upgradient wells are from 17 to

  5. Study on measurement of the coal powder concentration in pneumatic pipes of a boiler with relationship between air velocity and pressure drop

    SciTech Connect

    Pan, W.; Shen, F.; Lin, W.; Chen, L.; Zhang, D.; Wang, Q.; Ke, J.; Quan, W.

    1999-07-01

    According to the theoretical relationship between air velocity and pressure drop in different solid-air mass flow in vertical pipes with the condition of upward air-solid flowing, the experimental research on measuring the coal powder concentration is directed against the pneumatic pipes of a boiler's combustion system in the energy industry. Through analyzing the experimental results, a mathematical model for measuring the coal powder concentration in pneumatic pipes is obtained. Then, the error analysis is done, and the method of on-line measurement and its function are provided.

  6. A complexity measure based method for studying the dependance of 222Rn concentration time series on indoor air temperature and humidity.

    PubMed

    Mihailovic, D T; Udovičić, V; Krmar, M; Arsenić, I

    2014-02-01

    We have suggested a complexity measure based method for studying the dependence of measured (222)Rn concentration time series on indoor air temperature and humidity. This method is based on the Kolmogorov complexity (KL). We have introduced (i) the sequence of the KL, (ii) the Kolmogorov complexity highest value in the sequence (KLM) and (iii) the KL of the product of time series. The noticed loss of the KLM complexity of (222)Rn concentration time series can be attributed to the indoor air humidity that keeps the radon daughters in air.

  7. Development of Land Use Regression models for particulate matter and associated components in a low air pollutant concentration airshed

    NASA Astrophysics Data System (ADS)

    Dirgawati, Mila; Heyworth, Jane S.; Wheeler, Amanda J.; McCaul, Kieran A.; Blake, David; Boeyen, Jonathon; Cope, Martin; Yeap, Bu Beng; Nieuwenhuijsen, Mark; Brunekreef, Bert; Hinwood, Andrea

    2016-11-01

    Perth, Western Australia represents an area where pollutant concentrations are considered low compared with international locations. Land Use Regression (LUR) models for PM10, PM2.5 and PM2.5 Absorbance (PM2.5Abs) along with their elemental components: Fe, K, Mn, V, S, Zn and Si were developed for the Perth Metropolitan area in order to estimate air pollutant concentrations across Perth. The most important predictor for PM10 was green spaces. Heavy vehicle traffic load was found to be the strongest predictor for PM2.5Abs. Traffic variables were observed to be the important contributors for PM10 and PM2.5 elements in Perth, except for PM2.5 V which had distance to coast as the predominant predictor. Open green spaces explained more of the variability in the PM10 elements than for PM2.5 elements, and population density was more important for PM2.5 elements than for PM10 elements. The PM2.5 and PM2.5Abs LUR models explained 67% and 82% of the variance, respectively, but the PM10 model only explained 35% of the variance. The PM2.5 models for Mn, V, and Zn explained between 70% and 90% of the variability in concentrations. PM10 V, Si, K, S and Fe models explained between 53% and 71% of the variability in respective concentrations. Testing the models using leave one-out cross validation, hold out validation and cross-hold out validation supported the validity of LUR models for PM10, PM2.5 and PM2.5Abs and their corresponding elements in Metropolitan Perth despite the relatively low concentrations.

  8. The potential of LIRIC to validate the vertical profiles of the aerosol mass concentration estimated by an air quality model

    NASA Astrophysics Data System (ADS)

    Siomos, Nikolaos; Filoglou, Maria; Poupkou, Anastasia; Liora, Natalia; Dimopoulos, Spyros; Melas, Dimitris; Chaikovsky, Anatoli; Balis, Dimitris

    2015-04-01

    Vertical profiles of the aerosol mass concentration derived by a retrieval algorithm that uses combined sunphotometer and LIDAR data (LIRIC) were used in order to validate the mass concentration profiles estimated by the air quality model CAMx. LIDAR and CIMEL measurements of the Laboratory of Atmospheric Physics of the Aristotle University of Thessaloniki were used for this validation.The aerosol mass concentration profiles of the fine and coarse mode derived by CAMx were compared with the respective profiles derived by the retrieval algorithm. For the coarse mode particles, forecasts of the Saharan dust transportation model BSC-DREAM8bV2 were also taken into account. Each of the retrieval algorithm's profiles were matched to the models' profile with the best agreement within a time window of four hours before and after the central measurement. OPAC, a software than can provide optical properties of aerosol mixtures, was also employed in order to calculate the angstrom exponent and the lidar ratio values for 355nm and 532nm for each of the model's profiles aiming in a comparison with the angstrom exponent and the lidar ratio values derived by the retrieval algorithm for each measurement. The comparisons between the fine mode aerosol concentration profiles resulted in a good agreement between CAMx and the retrieval algorithm, with the vertical mean bias error never exceeding 7 μgr/m3. Concerning the aerosol coarse mode concentration profiles both CAMx and BSC-DREAM8bV2 values are severely underestimated, although, in cases of Saharan dust transportation events there is an agreement between the profiles of BSC-DREAM8bV2 model and the retrieval algorithm.

  9. Variations in vanadium, nickel and lanthanoid element concentrations in urban air.

    PubMed

    Moreno, Teresa; Querol, Xavier; Alastuey, Andrés; de la Rosa, Jesús; Sánchez de la Campa, Ana María; Minguillón, Maricruz; Pandolfi, Marco; González-Castanedo, Yolanda; Monfort, Eliseo; Gibbons, Wes

    2010-09-15

    The emission of trace metal pollutants by industry and transport takes place on a scale large enough to alter atmospheric chemistry and results in measurable differences between the urban background of inhalable particulate matter (PM) in different towns. This is particularly well demonstrated by the technogenic release into the atmosphere of V, Ni, and lanthanoid elements. We compare PM concentrations of these metals in large datasets from five industrial towns in Spain variously influenced by emissions from refinery, power station, shipping, stainless steel, ceramic tiles and brick-making. Increased La/Ce values in urban background inhalable PM, due to La-contamination from refineries and their residual products (fuel oils and petcoke), contrast with Ce-rich emissions from the ceramic related industry, and clearly demonstrate the value of this ratio as a sensitive and reliable tracer for many point source emissions. Similarly, anomalously high V/Ni values (>4) can detect the influence of nearby high-V petcoke and fuel oil combustion, although the use of this ratio in urban background PM is limited by overlapping values in natural and anthropogenic materials. Geochemical characterisation of urban background PM is a valuable compliment to the physical monitoring of aerosols widely employed in urban areas, especially given the relevance of trace metal inhalation to urban health issues.

  10. [Responses of Ilex integra Thunb. seedlings to elevated air ozone concentration].

    PubMed

    Zhang, Wei-Wei; Niu, Jun-Feng; Feng, Zhao-Zhong; Wang, Xiao-Ke; Tian, Yan; Yao, Fang-Fang

    2011-08-01

    One-year-old Ilex integra seedlings were exposed to charcoal-filtered (CF) and elevated ozone (E-O3, approximately 150 microL x L(-1)) for 84 days in six open-top chambers. Visible injury, growth parameters, pigments content, gas exchange, chlorophyll a fluorescence and antioxidant system were investigated during the growing season. At the end of experiment, foliage showed remarkable visible symptoms with dark-brown necrotic spots and patches which were concaved on the upper surface of the current-year leaves. Although relative height and diameter increment, total biomass and specific leaf weight (SLW) remained unaffected, E-O3 significantly decreased the percentage of stem biomass in total biomass. E-O3 induced significant decrease in net photosynthetic rate, chlorophyll a/b ratio and total phenolic compound content by 19%, 9% and 36%, respectively. However, stomatal conductance, intercellular CO2 concentration, chlorophyll a fluorescence parameters, pigment contents, MDA contents, total antioxidant capacity and total ascorbate content remained unaffected by E-O3. The results suggested that E-O3-induced change in components of chlorophyll contributed to the reduction of photosynthesis in Ilex integra seedlings. In addition, although visible symptom was found during the experiment, antioxidant system, most of the physiological parameters and growth were not significantly affected by E-O3.

  11. Linking climate and air quality over Europe: effects of meteorology on PM2.5 concentrations

    NASA Astrophysics Data System (ADS)

    Megaritis, A. G.; Fountoukis, C.; Charalampidis, P. E.; Denier van der Gon, H. A. C.; Pilinis, C.; Pandis, S. N.

    2014-04-01

    The effects of various meteorological parameters such as temperature, wind speed, absolute humidity, precipitation and mixing height on PM2.5 concentrations over Europe were examined using a three-dimensional chemical transport model, PMCAMx-2008. Our simulations covered three periods, representative of different seasons (summer, winter, and fall). PM2.5 appears to be more sensitive to temperature changes compared to the other meteorological parameters in all seasons. PM2.5 generally decreases as temperature increases, although the predicted changes vary significantly in space and time, ranging from -700 ng m-3 K-1 (-8% K-1) to 300 ng m-3 K-1 (7% K-1). The predicted decreases of PM2.5 are mainly due to evaporation of ammonium nitrate, while the higher biogenic emissions and the accelerated gas-phase reaction rates increase the production of organic aerosol (OA) and sulfate, having the opposite effect on PM2.5. The predicted responses of PM2.5 to absolute humidity are also quite variable, ranging from -130 ng m-3%-1 (-1.6% %-1) to 160 ng m-3 %-1 (1.6% %-1) dominated mainly by changes in inorganic PM2.5 species. An increase in absolute humidity favors the partitioning of nitrate to the aerosol phase and increases the average PM2.5 during summer and fall. Decreases in sulfate and sea salt levels govern the average PM2.5 response to humidity during winter. A decrease of wind speed (keeping constant the emissions) increases all PM2.5 species (on average 40 ng m-3 %-1) due to changes in dispersion and dry deposition. The wind speed effects on sea salt emissions are significant for PM2.5 concentrations over water and in coastal areas. Increases in precipitation have a negative effect on PM2.5 (decreases up to 110 ng m-3 %-1) in all periods due to increases in wet deposition of PM2.5 species and their gas precursors. Changes in mixing height have the smallest effects (up to 35 ng m-3 %-1) on PM2.5. Regarding the relative importance of each of the meteorological parameters

  12. Linking climate and air quality over Europe: effects of meteorology on PM2.5 concentrations

    NASA Astrophysics Data System (ADS)

    Megaritis, A. G.; Fountoukis, C.; Charalampidis, P. E.; Denier van der Gon, H. A. C.; Pilinis, C.; Pandis, S. N.

    2014-09-01

    The effects of various meteorological parameters such as temperature, wind speed, absolute humidity, precipitation and mixing height on PM2.5 concentrations over Europe were examined using a three-dimensional chemical transport model, PMCAMx-2008. Our simulations covered three periods, representative of different seasons (summer, winter, and fall). PM2.5 appears to be more sensitive to temperature changes compared to the other meteorological parameters in all seasons. PM2.5 generally decreases as temperature increases, although the predicted changes vary significantly in space and time, ranging from -700 ng m-3 K-1 (-8% K-1) to 300 ng m-3 K-1 (7% K-1). The predicted decreases of PM2.5 are mainly due to evaporation of ammonium nitrate, while the higher biogenic emissions and the accelerated gas-phase reaction rates increase the production of organic aerosol (OA) and sulfate, having the opposite effect on PM2.5. The predicted responses of PM2.5 to absolute humidity are also quite variable, ranging from -130 ng m-3 %-1 (-1.6% %-1) to 160 ng m-3 %-1 (1.6% %-1) dominated mainly by changes in inorganic PM2.5 species. An increase in absolute humidity favors the partitioning of nitrate to the aerosol phase and increases the average PM2.5 during summer and fall. Decreases in sulfate and sea salt levels govern the average PM2.5 response to humidity during winter. A decrease of wind speed (keeping the emissions constant) increases all PM2.5 species (on average 40 ng m-3 %-1) due to changes in dispersion and dry deposition. The wind speed effects on sea salt emissions are significant for PM2.5 concentrations over water and in coastal areas. Increases in precipitation have a negative effect on PM2.5 (decreases up to 110 ng m-3 %-1) in all periods due to increases in wet deposition of PM2.5 species and their gas precursors. Changes in mixing height have the smallest effects (up to 35 ng m-3 %-1) on PM2.5 . Regarding the relative importance of each of the meteorological

  13. On the effect of pressure, oxygen concentration, air flow and gravity on simulated pool fires

    NASA Technical Reports Server (NTRS)

    Torero, J. L.; Most, J. M.; Joulain, P.

    1995-01-01

    The initial development of a fire is characterized by the establishment of a diffusion flame over the surface of a the condensed fuel and is particularly influenced by gravity, with most of the gaseous flow induced by natural convection. Low initial momentum of the fuel vapor, strong buoyant flows induced by the hot post-combustion gases and consequently low values of the Froude number (inertia-gravity forces ratio) are typical of this kind of scenario. An experimental study is conducted by using a porous burner to simulate the burning of a horizontal combustible surface. Ethane is used as fuel and different mixtures of oxygen and nitrogen as oxidizer. The magnitude of the fuel injection velocities is restricted to values that will keep the Froude number on the order of 10-5, when calculated at normal gravity and pressure, which are characteristic of condensed fuel burning. Two different burners are used, a circular burner (62 mm diameter) placed inside a cylindrical chamber (0.3 m diameter and 1.0 m height) and a rectangular burner (50 mm wide by 200 mm long) placed in a wind tunnel (350 mm long) of rectangular cross section (120 mm wide and 90 mm height). The first burner is used to study the effect of pressure and gravity in the absence of a forced flow parallel to the surface. The second burner is used to study the effect of a forced flow parallel to the burner surface as well as the effect of oxygen concentration in the oxidizer flow. In this case experiments are also conducted at different gravity levels (micro-gravity, 0.2 g(sub 0), g(sub 0) and 1.8 g(sub 0)) to quantify the relative importance of buoyancy.

  14. Effect of spatial outliers on the regression modelling of air pollutant concentrations: A case study in Japan

    NASA Astrophysics Data System (ADS)

    Araki, Shin; Shimadera, Hikari; Yamamoto, Kouhei; Kondo, Akira

    2017-03-01

    Land use regression (LUR) or regression kriging have been widely used to estimate spatial distribution of air pollutants especially in health studies. The quality of observations is crucial to these methods because they are completely dependent on observations. When monitoring data contain biases or uncertainties, estimated map will not be reliable. In this study, we apply the spatial outlier detection method, which is widely used in soil science, to observations of PM2.5 and NO2 obtained from the regulatory monitoring network in Japan. The spatial distributions of annual means are modelled both by LUR and regression kriging using the data sets with and without the detected outliers respectively and the obtained results are compared to examine the effect of spatial outliers. Spatial outliers remarkably deteriorate the prediction accuracy except for that of LUR model for NO2. This discrepancy of the effect might be due to the difference in the characteristics of PM2.5 and NO2. The difference in the number of observations makes a limited contribution to it. Although further investigation at different spatial scales is required, our study demonstrated that the spatial outlier detection method is an effective procedure for air pollutant data and should be applied to it when observation based prediction methods are used to generate concentration maps.

  15. Influence of the meteorological parameters on CFCs and SF6 concentration in the air of Krakow, Poland

    NASA Astrophysics Data System (ADS)

    Bielewski, Jarosław; Najman, Joanna; Śliwka, Ireneusz; Bartyzel, Jakub; Rosiek, Janusz

    2013-04-01

    key words: gas chromatography, trace gases, CFCs and SF6 measurements in urban area. Halogenated compounds (chlorofluorocarbons-CFCs), both natural and industrial, so-called freons, currently exist as trace gases in the entire human environment. The CFCs cause ozone depletion in the stratosphere. Moreover CFCs and SF6 take part in intensification of the greenhouse effect. The decisions of the Vienna Convention (1985) and of the Montreal Protocol (1987) limited the world production level of CFCs in the year 1989 at least 35% after 2004, 90% after 2015 and total reduction after year 2030. On account of international agreements, the measurements of CFCs and SF6 in air were started. Measurement "clean" stations were situated at places outside of urban areas influence and gathered on world program - AGAGE (Advanced Global Atmospheric Gases Experiment). One of these stations is Mace Head (Ireland, 53o N, 10o W), which participates in AGAGE since 1987 [1] and in European InGOS (Integrated non-CO2 Greenhouse gas Observing System) program since 2011. Similar research is also conducted in Central Europe, in urban area of Krakow (Poland, 50o N, 19o E) since 1997. The work discusses results from 15 years of concentration measurements (in the years 1997-2012) of selected halocarbons and SF6 in Krakow. To obtain concentrations of measured compounds the mathematical procedure has been used, where concentrations were calculated using a five points Lagrange's interpolation method. Using temporary measurement data were determined daily arithmetic means and their standard deviations. Based on these data, efficiency of Montreal Protocol legislation, implemented in Poland (The Journal of Laws No. 52) could be assessed [2]. Additionally cut-off filtration method was used to estimate trend of the base line of individual air pollutant. Rejected exceedances of base lines were corelated with meteorological characteristics of Krakow region to evaluate possible sources of pollution. The

  16. Source Term Estimates of Radioxenon Released from the BaTek Medical Isotope Production Facility Using External Measured Air Concentrations

    SciTech Connect

    Eslinger, Paul W.; Cameron, Ian M.; Dumais, Johannes R.; Imardjoko, Yudi; Marsoem, Pujadi; McIntyre, Justin I.; Miley, Harry S.; Stoehlker, Ulrich; Widodo, Susilo; Woods, Vincent T.

    2015-10-01

    Abstract Batan Teknologi (BaTek) operates an isotope production facility in Serpong, Indonesia that supplies 99mTc for use in medical procedures. Atmospheric releases of Xe-133 in the production process at BaTek are known to influence the measurements taken at the closest stations of the International Monitoring System (IMS). The purpose of the IMS is to detect evidence of nuclear explosions, including atmospheric releases of radionuclides. The xenon isotopes released from BaTek are the same as those produced in a nuclear explosion, but the isotopic ratios are different. Knowledge of the magnitude of releases from the isotope production facility helps inform analysts trying to decide whether a specific measurement result came from a nuclear explosion. A stack monitor deployed at BaTek in 2013 measured releases to the atmosphere for several isotopes. The facility operates on a weekly cycle, and the stack data for June 15-21, 2013 show a release of 1.84E13 Bq of Xe-133. Concentrations of Xe-133 in the air are available at the same time from a xenon sampler located 14 km from BaTek. An optimization process using atmospheric transport modeling and the sampler air concentrations produced a release estimate of 1.88E13 Bq. The same optimization process yielded a release estimate of 1.70E13 Bq for a different week in 2012. The stack release value and the two optimized estimates are all within 10 percent of each other. Weekly release estimates of 1.8E13 Bq and a 40 percent facility operation rate yields a rough annual release estimate of 3.7E13 Bq of Xe-133. This value is consistent with previously published estimates of annual releases for this facility, which are based on measurements at three IMS stations. These multiple lines of evidence cross-validate the stack release estimates and the release estimates from atmospheric samplers.

  17. Modeling and forecasting daily movement of ambient air mean PM₂.₅ concentration based on the elliptic orbit model with weekly quasi-periodic extension: a case study.

    PubMed

    Yang, Zong-chang

    2014-01-01

    Nowadays, the issue of air pollution has continuously been a global public health concern. Modeling and forecasting daily movement of ambient air mean PM2.5 concentration is an increasingly important task as it is intimately associated with human health that the air pollution has unignorable negative effects in reducing air quality, damaging environment, even causing serious harm to health. It is demonstrated that daily movement of mean PM₂.₅ concentration approximately exhibits weekly cyclical variations as daily particle pollution in the air is largely influenced by human daily activities. Then, based on weekly quasi-periodic extension for daily movement of mean PM₂.₅ concentration, the called elliptic orbit model is proposed to describe its movement. By mapping daily movement of mean PM₂.₅ concentration as one time series into the polar coordinates, each 7-day movement is depicted as one elliptic orbit. Experimental result and analysis indicate workability and effectiveness of the proposed method. Here we show that with the weekly quasi-periodic extension, daily movements of mean PM₂.₅ concentration at the given monitoring stations in Xiangtan of China are well described by the elliptic orbit model, which provides a vivid description for modeling and prediction daily movement of mean PM₂.₅ concentration in a concise and intuitive way.

  18. System Design Description for the SY-101 Hydrogen Mitigation Test Project Data Acquisition and Control System (DACS-1)

    SciTech Connect

    ERMI, A.M.

    2000-01-24

    This document describes the hardware and software of the computer subsystems for the Data Acquisition and Control System (DACS) used in mitigation tests conducted on waste tank 241-SY-101 at the Hanford Nuclear Reservation.

  19. Multi-year levels and trends of non-methane hydrocarbon concentrations observed in ambient air in France

    NASA Astrophysics Data System (ADS)

    Waked, Antoine; Sauvage, Stéphane; Borbon, Agnès; Gauduin, Julie; Pallares, Cyril; Vagnot, Marie-Pierre; Léonardis, Thierry; Locoge, Nadine

    2016-09-01

    Measurements of 31 non-methane hydrocarbons (NMHCs) were carried out at three urban (Paris, 2003-2014, Strasbourg, 2002-2014 and Lyon, 2007-2014) sites in France over the period of a decade. A trend analysis was applied by means of the Mann-Kendall non-parametric test to annual and seasonal mean concentrations in order to point out changes in specific emission sources and to assess the impact of emission controls and reduction strategies. The trends were compared to those from three rural sites (Peyrusse-Vieille, 2002-2013, Tardière, 2003-2013 and Donon, 1997-2007). The results obtained showed a significant yearly decrease in pollutant concentrations over the study period and for the majority of species in the range of -1 to -7% in accordance with the decrease of NMHC emissions in France (-5 to -9%). Concentrations of long-lived species such as ethane and propane which are recognized as tracers of distant sources and natural gas remained constant. Compounds associated with combustion processes such as acetylene, propene, ethylene and benzene showed a significant decline in the range of -2% to -5% yr-1. These trends are consistent with those recently described at urban and background sites in the northern mid-latitudes and with emission inventories. C7-C9 aromatics such as toluene and xylenes as well as C4-C5 alkanes such as isopentane and isobutane also showed a significant decrease in the range of -3% to -7% yr-1. The decreasing trends in terms of % yr-1 observed at these French urban sites were typically higher for acetylene, ethylene and benzene than those reported for French rural sites of the national observatory of Measurement and Evaluation in Rural areas of trans-boundary Air pollution (MERA). The study also highlighted the difficult choice of a long term sampling site representative of the general trends of pollutant concentrations.

  20. Probabilistic approach to estimating indoor air concentrations of chlorinated volatile organic compounds from contaminated groundwater: a case study in San Antonio, Texas.

    PubMed

    Johnston, Jill E; Gibson, Jacqueline MacDonald

    2011-02-01

    This paper describes a probabilistic model, based on the Johnson-Ettinger algorithm, developed to characterize the current and historic exposure to tricholorethylene (TCE) and tetrachlorethylene (PCE) in indoor air from plumes of groundwater contamination emanating from the former Kelly Air Force Base in San Antonio, Texas. We estimate indoor air concentration, house by house, in 30 101 homes and compare the estimated concentrations with measured values in a small subset of homes. We also compare two versions of the Johnson-Ettinger model: one used by the Environmental Protection Agency (EPA) and another based on an alternative parametrization. The modeled mean predicted PCE concentration historically exceeded PCE screening levels (0.41 ug/m(3)) in 5.5% of houses, and the 95th percentile of the predicted concentration exceeded screening levels in 85.3% of houses. For TCE, the mean concentration exceeded the screening level (0.25 ug/m(3)) in 49% of homes, and the 95th percentile of the predicted concentration exceeded the screening level in 99% of homes. The EPA model predicts slightly lower indoor concentrations than the alternative parametrization. Comparison with measured samples suggests both models, with the inputs selected, underestimate indoor concentrations and that the 95th percentiles of the predicted concentrations are closer to measured concentrations than predicted mean values.

  1. Results of the California Healthy Homes Indoor Air Quality Study of 2011-2013: Impact of natural gas appliances on air pollutant concentrations

    DOE PAGES

    Mullen, Nasim A.; Li, Jina; Russell, Marion L.; ...

    2015-03-17

    This study was conducted to assess the current impact of natural gas appliances on air quality in California homes. Data were collected via telephone interviews and measurements inside and outside of 352 homes. Passive samplers measured time-resolved CO and time-integrated NOX, NO2, formaldehyde, and acetaldehyde over ~6d periods in November 2011 - April 2012 and October 2012 - March 2013. The fraction of indoor NOX and NO2 attributable to indoor sources was estimated. NOX, NO2 and highest 1-h CO were higher in homes that cooked with gas and increased with amount of gas cooking. NOX and NO2 were higher inmore » homes with cooktop pilot burners, relative to gas cooking without pilots. Homes with a pilot burner on a floor or wall furnace had higher kitchen and bedroom NOX and NO2 compared to homes without a furnace pilot. When scaled to account for varying home size and mixing volume, indoor-attributed bedroom and kitchen NOX and kitchen NO2 were not higher in homes with wall or floor furnace pilot burners, though bedroom NO2 was higher. In homes that cooked 4 h or more with gas, self-reported use of kitchen exhaust was associated with lower NOX, NO2 and highest 1-h CO. Gas appliances were not associated with higher concentrations of formaldehyde or acetaldehyde.« less

  2. Results of the California Healthy Homes Indoor Air Quality Study of 2011-2013: impact of natural gas appliances on air pollutant concentrations.

    PubMed

    Mullen, N A; Li, J; Russell, M L; Spears, M; Less, B D; Singer, B C

    2016-04-01

    This study was conducted to assess the current impact of natural gas appliances on air quality in California homes. Data were collected via telephone interviews and measurements inside and outside of 352 homes. Passive samplers measured time-resolved CO and time-integrated NOX , NO2 , formaldehyde, and acetaldehyde over ~6-day periods in November 2011 - April 2012 and October 2012 - March 2013. The fraction of indoor NOX and NO2 attributable to indoor sources was estimated. NOX , NO2 , and highest 1-h CO were higher in homes that cooked with gas and increased with amount of gas cooking. NOX and NO2 were higher in homes with cooktop pilot burners, relative to gas cooking without pilots. Homes with a pilot burner on a floor or wall furnace had higher kitchen and bedroom NOX and NO2 compared to homes without a furnace pilot. When scaled to account for varying home size and mixing volume, indoor-attributed bedroom and kitchen NOX and kitchen NO2 were not higher in homes with wall or floor furnace pilot burners, although bedroom NO2 was higher. In homes that cooked 4 h or more with gas, self-reported use of kitchen exhaust was associated with lower NOX , NO2 , and highest 1-h CO. Gas appliances were not associated with higher concentrations of formaldehyde or acetaldehyde.

  3. Mouse Dac, a novel nuclear factor with homology to Drosophila dachshund shows a dynamic expression in the neural crest, the eye, the neocortex, and the limb bud.

    PubMed

    Caubit, X; Thangarajah, R; Theil, T; Wirth, J; Nothwang, H G; Rüther, U; Krauss, S

    1999-01-01

    Dac is a novel nuclear factor in mouse and humans that shares homology with Drosophila dachshund (dac). Alignment with available sequences defines a conserved box of 117 amino acids that shares weak homology with the proto-oncogene Ski and Sno. Dac expression is found in various neuroectodermal and mesenchymal tissues. At early developmental stages Dac is expressed in lateral mesoderm and in neural crest cells. In the neural plate/tube Dac expression is initially seen in the prosencephalon and gets gradually restricted to the presumptive neocortex and the distal portion of the outgrowing optic vesicle. Furthermore, Dac transcripts are detected in the mesenchyme underlying the Apical Ectodermal Ridge (AER) of the extending limb bud, the dorsal root ganglia and chain ganglia, and the mesenchyme of the growing genitalia. Dac expression in the Gli 3 mutant extra toes (Xt/Xt) shows little difference compared to the expression in wild-type limb buds. In contrast, a significant expansion of Dac expression are observed in the anterior mesenchyme of the limb buds of hemimelic extra toes (Hx/+) mice. FISH analysis reveals that human DAC maps to chromosome 13q22.3-23 and further fine-mapping defined a position of the DAC gene at 54cM or 13q21.1, a locus that associates with mental retardation and skeletal abnormalities.

  4. A low-cost DAC BIST structure using a resistor loop

    PubMed Central

    Jang, Jaewon; Kim, Heetae

    2017-01-01

    This paper proposes a new DAC BIST (digital-to-analog converter built-in self-test) structure using a resistor loop known as a DDEM ADC (deterministic dynamic element matching analog-to-digital converter). Methods for both switch reduction and switch effect reduction are proposed for solving problems related to area overhead and accuracy of the conventional DAC BIST. The proposed BIST modifies the length of each resistor in the resistor loop via a merging operation and reduces the number of switches and resistors. In addition, the effect of switches is mitigated using the proposed switch effect reduction method. The accuracy of the proposed BIST is demonstrated by the reduction in the switch effect. The experimental results show that the proposed BIST reduces resource usages and the mismatch error caused by the switches. PMID:28212421

  5. Low-power DAC-less PAM-4 transmitter using a cascaded microring modulator.

    PubMed

    Dubé-Demers, Raphaël; LaRochelle, Sophie; Shi, Wei

    2016-11-15

    Future super-computer interconnect systems and data centers request ultrahigh data rate links at low cost and power consumption, for which transmitters with a high level of integration and spectral efficient formats are key components. We report 60 Gb/s pulse-amplitude modulation (PAM-4) of an optical signal using a dual-microring silicon photonics circuit, making a low-power, digital-to-analog converter (DAC)-less PAM modulator. The power consumption is evaluated below 100 fJ/bit, including thermal adjustments. To the best of our knowledge, these results feature the lowest reported power consumption for PAM signaling in a DAC-less scheme for data rate beyond 40 Gb/s.

  6. Linearity analysis of single-ended SAR ADC with split capacitive DAC

    NASA Astrophysics Data System (ADS)

    Osipov, Dmitry; Malankin, Evgeny; Shumikhin, Vitaly

    2016-10-01

    This paper proposes the design of a 6-bit single-ended SAR ADC with a variable sampling rate at a maximum achievable speed of 50 MS/s. The SAR ADC utilizes the split capacitor array DAC with a non-conventional split-capacitor value. The influence of switches in the capacitive DAC on the ADC's non-linearity is analysed. According to the fulfilled analysis the recommendations for switches and capacitor array dimensioning are given to provide a minimum differential non-linearity (DNL). At a sampling rate of 50 MS/s, the SAR ADC achieves an ENOB of 5.4 bit at an input signal frequency of 1 MHz and consumes 1.2 mW at a 1.8 V power supply, resulting in an energy efficiency of 568 fJ/conv.-step. The SAR ADC was simulated with parasitics in a standard 180nm CMOS process.

  7. The DAC system and associations with acute leukemias and myelodysplastic syndromes.

    PubMed

    Bug, Gesine; Ottmann, Oliver G

    2010-12-01

    Imbalances of histone acetyltransferase (HAT) and deacetylase activity (DAC) that result in deregulated gene expression are commonly observed in leukemias. These alterations provide the basis for novel therapeutic approaches that target the epigenetic mechanisms implicated in leukemogenesis. As the acetylation status of histones has been linked to transcriptional regulation of genes involved particularly in differentiation and apoptosis, DAC inhibitors (DACi) have attracted considerable attention for treatment of hematologic malignancies. DACi encompass a structurally diverse family of compounds that are being explored as single agents as well as in combination with chemotherapeutic drugs, small molecule inhibitors of signaling pathways and hypomethylating agents. While DACi have shown clear evidence of activity in acute myeloid leukemia, myelodysplastic syndromes and lymphoid malignancies, their precise role in treatment of these different entities remain to be elucidated. Successful development of these compounds as elements of novel targeted treatment strategies for leukemia will require that clinical studies be performed in conjunction with translational research including efforts to identify predictive biomarkers.

  8. A low-cost DAC BIST structure using a resistor loop.

    PubMed

    Jang, Jaewon; Kim, Heetae; Kang, Sungho

    2017-01-01

    This paper proposes a new DAC BIST (digital-to-analog converter built-in self-test) structure using a resistor loop known as a DDEM ADC (deterministic dynamic element matching analog-to-digital converter). Methods for both switch reduction and switch effect reduction are proposed for solving problems related to area overhead and accuracy of the conventional DAC BIST. The proposed BIST modifies the length of each resistor in the resistor loop via a merging operation and reduces the number of switches and resistors. In addition, the effect of switches is mitigated using the proposed switch effect reduction method. The accuracy of the proposed BIST is demonstrated by the reduction in the switch effect. The experimental results show that the proposed BIST reduces resource usages and the mismatch error caused by the switches.

  9. Vapor-phase and particulate-associated pesticides and PCB concentrations in eastern North Dakota air samples

    SciTech Connect

    Hawthorne, S.B.; Miller, D.J.; Louie, P.K.K.

    1996-05-01

    Vapor-phase and suspended particulate (<50 {mu}m) samples were collected on polyurethane foam (PUF) and quartz fiber filters in rural North Dakota to determine the air concentrations of pesticides in an area where agriculture is a primary source of semivolatile pollutants. Samples were collected at two sites from 1992 to 1994 that were at least 0.4 km from the nearest farmed fields and known application of pesticides, and analyzed for 22 different organochlorine, triazine, and acid herbicide pesticides. Fourteen pesticides were found above the detection limits (typically <1 pg/m{sup 3}). Concentrations of polychlorinated biphenyl (PCB) congeners were much lower (<50 pg/m{sup 3} in all cases) than many of the pesticides. These results demonstrate that pesticides are among the most prevalent chlorinated semivolatile pollutants present in rural North Dakota, that significant transport of pesticides occurs both in the vapor-phase and on suspended particulate matter, and that blown soil may be a significant mechanism for introducing pesticides into surface and ground waters. 32 refs., 2 figs., 4 tabs.

  10. SciDAC Visualization and Analytics Center for EnablingTechnology

    SciTech Connect

    Bethel, E. Wes; Johnson, Chris; Joy, Ken; Ahern, Sean; Pascucci,Valerio; Childs, Hank; Cohen, Jonathan; Duchaineau, Mark; Hamann, Bernd; Hansen, Charles; Laney, Dan; Lindstrom, Peter; Meredith, Jeremy; Ostrouchov, George; Parker, Steven; Silva, Claudio; Sanderson, Allen; Tricoche, Xavier

    2006-11-28

    The SciDAC2 Visualization and Analytics Center for EnablingTechnologies (VACET) began operation on 10/1/2006. This document, dated11/27/2006, is the first version of the VACET project management plan. Itwas requested by and delivered to ASCR/DOE. It outlines the Center'saccomplishments in the first six weeks of operation along with broadobjectives for the upcoming future (12-24 months).

  11. SciDAC Center for Gyrokinetic Particle Simulation of Turbulent Transport in Burning Plasmas

    SciTech Connect

    Lin, Zhihong

    2013-12-18

    During the first year of the SciDAC gyrokinetic particle simulation (GPS) project, the GPS team (Zhihong Lin, Liu Chen, Yasutaro Nishimura, and Igor Holod) at the University of California, Irvine (UCI) studied the tokamak electron transport driven by electron temperature gradient (ETG) turbulence, and by trapped electron mode (TEM) turbulence and ion temperature gradient (ITG) turbulence with kinetic electron effects, extended our studies of ITG turbulence spreading to core-edge coupling. We have developed and optimized an elliptic solver using finite element method (FEM), which enables the implementation of advanced kinetic electron models (split-weight scheme and hybrid model) in the SciDAC GPS production code GTC. The GTC code has been ported and optimized on both scalar and vector parallel computer architectures, and is being transformed into objected-oriented style to facilitate collaborative code development. During this period, the UCI team members presented 11 invited talks at major national and international conferences, published 22 papers in peer-reviewed journals and 10 papers in conference proceedings. The UCI hosted the annual SciDAC Workshop on Plasma Turbulence sponsored by the GPS Center, 2005-2007. The workshop was attended by about fifties US and foreign researchers and financially sponsored several gradual students from MIT, Princeton University, Germany, Switzerland, and Finland. A new SciDAC postdoc, Igor Holod, has arrived at UCI to initiate global particle simulation of magnetohydrodynamics turbulence driven by energetic particle modes. The PI, Z. Lin, has been promoted to the Associate Professor with tenure at UCI.

  12. Modeled and monitored variation in space and time of PCB-153 concentrations in air, sediment, soil and aquatic biota on a European scale.

    PubMed

    Hauck, Mara; Huijbregts, Mark A J; Hollander, Anne; Hendriks, A Jan; van de Meent, Dik

    2010-08-15

    We evaluated various modeling options for estimating concentrations of PCB-153 in the environment and in biota across Europe, using a nested multimedia fate model coupled with a bioaccumulation model. The most detailed model set up estimates concentrations in air, soil, fresh water sediment and fresh water biota with spatially explicit environmental characteristics and spatially explicit emissions to air and water in the period 1930-2005. Model performance was evaluated with the root mean square error (RMSE(log)), based on the difference between estimated and measured concentrations. The RMSE(log) was 5.4 for air, 5.6-6.3 for sediment and biota, and 5.5 for soil in the most detailed model scenario. Generally, model estimations tended to underestimate observed values for all compartments, except air. The decline in observed concentrations was also slightly underestimated by the model for the period where measurements were available (1989-2002). Applying a generic model setup with averaged emissions and averaged environmental characteristics, the RMSE(log) increased to 21 for air and 49 for sediment. For soil the RMSE(log) decreased to 3.5. We found that including spatial variation in emissions was most relevant for all compartments, except soil, while including spatial variation in environmental characteristics was less influential. For improving predictions of concentrations in sediment and aquatic biota, including emissions to water was found to be relevant as well.

  13. The Dac-tag, an affinity tag based on penicillin-binding protein 5.

    PubMed

    Lee, David Wei; Peggie, Mark; Deak, Maria; Toth, Rachel; Gage, Zoe Olivia; Wood, Nicola; Schilde, Christina; Kurz, Thimo; Knebel, Axel

    2012-09-01

    Penicillin-binding protein 5 (PBP5), a product of the Escherichia coli gene dacA, possesses some β-lactamase activity. On binding to penicillin or related antibiotics via an ester bond, it deacylates and destroys them functionally by opening the β-lactam ring. This process takes several minutes. We exploited this process and showed that a fragment of PBP5 can be used as a reversible and monomeric affinity tag. At ambient temperature (e.g., 22°C), a PBP5 fragment binds rapidly and specifically to ampicillin Sepharose. Release can be facilitated either by eluting with 10mM ampicillin or in a ligand-free manner by incubation in the cold (1-10°C) in the presence of 5% glycerol. The "Dac-tag", named with reference to the gene dacA, allows the isolation of remarkably pure fusion protein from a wide variety of expression systems, including (in particular) eukaryotic expression systems.

  14. The potential of a dielectrophoresis activated cell sorter (DACS) as a next generation cell sorter

    NASA Astrophysics Data System (ADS)

    Lee, Dongkyu; Hwang, Bohyun; Kim, Byungkyu

    2016-12-01

    Originally introduced by H. A. Pohl in 1951, dielectrophoretic (DEP) force has been used as a striking tool for biological particle manipulation (or separation) for the last few decades. In particular, dielectrophoresis activated cell sorters (DACSes) have been developed for applications in various biomedical fields. These applications include cell replacement therapy, drug screening and medical diagnostics. Since a DACS does not require a specific bio-marker, it is able to function as a biological particle sorting tool with numerous configurations for various cells [e.g. red blood cells (RBCs), white blood cells (WBCs), circulating tumor cells, leukemia cells, breast cancer cells, bacterial cells, yeast cells and sperm cells]. This article explores current DACS capabilities worldwide, and it also looks at recent developments intended to overcome particular limitations. First, the basic theories are reviewed. Then, representative DACSes based on DEP trapping, traveling wave DEP systems, DEP field-flow fractionation and DEP barriers are introduced, and the strong and weak points of each DACS are discussed. Finally, for the purposes of commercialization, prerequisites regarding throughput, efficiency and recovery rates are discussed in detail through comparisons with commercial cell sorters (e.g. fluorescent activated and magnetic activated cell sorters).

  15. A CMOS Current Steering Neurostimulation Array With Integrated DAC Calibration and Charge Balancing.

    PubMed

    Greenwald, Elliot; Maier, Christoph; Wang, Qihong; Beaulieu, Robert; Etienne-Cummings, Ralph; Cauwenberghs, Gert; Thakor, Nitish

    2017-04-01

    An 8-channel current steerable, multi-phasic neural stimulator with on-chip current DAC calibration and residue nulling for precise charge balancing is presented. Each channel consists of two sub-binary radix DACs followed by wide-swing, high output impedance current buffers providing time-multiplexed source and sink outputs for anodic and cathodic stimulation. A single integrator is shared among channels and serves to calibrate DAC coefficients and to closely match the anodic and cathodic stimulation phases. Following calibration, the differential non-linearity is within ±0.3 LSB at 8-bit resolution, and the two stimulation phases are matched within 0.3%. Individual control in digital programming of stimulation coefficients across the array allows altering the spatial profile of current stimulation for selection of stimulation targets by current steering. Combined with the self-calibration and current matching functions, the current steering capabilities integrated on-chip support use in fully implanted neural interfaces with autonomous operation for and adaptive stimulation under variations in electrode and tissue conditions. As a proof-of-concept we applied current steering stimulation through a multi-channel cuff electrode on the sciatic nerve of a rat.

  16. ANEMOS: A computer code to estimate air concentrations and ground deposition rates for atmospheric nuclides emitted from multiple operating sources

    SciTech Connect

    Miller, C.W.; Sjoreen, A.L.; Begovich, C.L.; Hermann, O.W.

    1986-11-01

    This code estimates concentrations in air and ground deposition rates for Atmospheric Nuclides Emitted from Multiple Operating Sources. ANEMOS is one component of an integrated Computerized Radiological Risk Investigation System (CRRIS) developed for the US Environmental Protection Agency (EPA) for use in performing radiological assessments and in developing radiation standards. The concentrations and deposition rates calculated by ANEMOS are used in subsequent portions of the CRRIS for estimating doses and risks to man. The calculations made in ANEMOS are based on the use of a straight-line Gaussian plume atmospheric dispersion model with both dry and wet deposition parameter options. The code will accommodate a ground-level or elevated point and area source or windblown source. Adjustments may be made during the calculations for surface roughness, building wake effects, terrain height, wind speed at the height of release, the variation in plume rise as a function of downwind distance, and the in-growth and decay of daughter products in the plume as it travels downwind. ANEMOS can also accommodate multiple particle sizes and clearance classes, and it may be used to calculate the dose from a finite plume of gamma-ray-emitting radionuclides passing overhead. The output of this code is presented for 16 sectors of a circular grid. ANEMOS can calculate both the sector-average concentrations and deposition rates at a given set of downwind distances in each sector and the average of these quantities over an area within each sector bounded by two successive downwind distances. ANEMOS is designed to be used primarily for continuous, long-term radionuclide releases. This report describes the models used in the code, their computer implementation, the uncertainty associated with their use, and the use of ANEMOS in conjunction with other codes in the CRRIS. A listing of the code is included in Appendix C.

  17. Development of a selective medium for the determination of the spore concentrations of Botrytis cinerea in the air.

    PubMed

    Gielen, S; Aerts, R; Seels, B

    2003-01-01

    germination on selective media. From the results of these experiments a correction factor was calculated that will be used when spore concentrations have to be determined for air detections that are carried out in glasshouses.

  18. A comparison of principal components using TPCA and nonstationary principal component analysis on daily air-pollutant concentration series

    NASA Astrophysics Data System (ADS)

    Shen, Chenhua

    2017-02-01

    We applied traditional principal component analysis (TPCA) and nonstationary principal component analysis (NSPCA) to determine principal components in the six daily air-pollutant concentration series (SO2, NO2, CO, O3, PM2.5 and PM10) in Nanjing from January 2013 to March 2016. The results show that using TPCA, two principal components can reflect the variance of these series: primary pollutants (SO2, NO2, CO, PM2.5 and PM10) and secondary pollutants (e.g., O3). However, using NSPCA, three principal components can be determined to reflect the detrended variance of these series: 1) a mixture of primary and secondary pollutants, 2) primary pollutants and 3) secondary pollutants. Various approaches can obtain different principal components. This phenomenon is closely related to methods for calculating the cross-correlation between each of the air pollutants. NSPCA is a more applicable, reliable method for analyzing the principal components of a series in the presence of nonstationarity and for a long-range correlation than can TPCA. Moreover, using detrended cross-correlation analysis (DCCA), the cross-correlation between O3 and NO2 is negative at a short timescale and positive at a long timescale. In hourly timescales, O3 is negatively correlated with NO2 due to a photochemical interaction, and in daily timescales, O3 is positively correlated with NO2 because of the decomposition of O3. In monthly timescales, the cross-correlation between O3 with NO2 has similar performance to those of O3 with meteorological elements. DCCA is again shown to be more appropriate for disclosing the cross-correlation between series in the presence of nonstationarity than is Pearson's method. DCCA can improve our understanding of their interactional mechanisms.

  19. Validation and modelling of a novel diffusive sampler for determining concentrations of volatile organic compounds in air.

    PubMed

    Ballesta, Pascual Pérez; Grandesso, Emanuela; Field, Robert A; Cabrerizo, Ana

    2016-02-18

    A novel diffusive sampler that combines radial and axial diffusion has been developed that improves upon existing commercially available designs. The POcket Diffusive (POD) sampler has been validated under laboratory and field conditions for the measurements of VOCs in ambient air. Laboratory tests varied sampling conditions of temperature (-30-40 C), humidity (10-80%), wind velocity (0.1-4 m s(-1)), and concentration (0.5-50 μg m(-3)) for a number of specific VOCs. An overall uncertainty of circa 9% for the measurement of benzene is calculated for the validation tests, in compliance with the data quality objectives of the EU air quality directive 2008/50/EC. A semi-empirical diffusion model has been developed to estimate sampling rates for compounds that were not tested, and for conditions outside of tested ranges during validation. The diffusion model (and validation tests) shows a low influence of environmental conditions on the sampling rate for the POD sampler. Average reproducibility values of circa 3% are reported with overall sampling uncertainties ranging from 9% to 15%, for the whole range of tested conditions, depending on the compound. The adsorbent cartridge is compatible with existing thermal desorption systems in the market. The diffusive sampler can modify the sampling rate by changing the diffusive body within a range of different porosities. Field tests, conducted in parallel with independent quality controlled canister sampling, confirmed the ease of use and quality of VOC measurements with the POD sampler, for compounds that were, and were not, evaluated during laboratory tests.

  20. Impacts of anthropogenic emissions and cold air pools on urban to montane gradients of snowpack ion concentrations in the Wasatch Mountains, Utah

    NASA Astrophysics Data System (ADS)

    Hall, Steven J.; Maurer, Gregory; Hoch, Sebastian W.; Taylor, Raili; Bowling, David R.

    2014-12-01

    Urban montane valleys are often characterized by periodic wintertime temperature inversions (cold air pools) that increase atmospheric particulate matter concentrations, potentially stimulating the deposition of major ions to these snow-covered ecosystems. We assessed spatial and temporal patterns of ion concentrations in snow across urban to montane gradients in Salt Lake City, Utah, USA, and the adjacent Wasatch Mountains during January 2011, a period of several persistent cold air pools. Ion concentrations in fresh snow samples were greatest in urban sites, and were lower by factors of 4-130 in a remote high-elevation montane site. Adjacent undeveloped canyons experienced significant incursions of particulate-rich urban air during stable atmospheric conditions, where snow ion concentrations were lower but not significantly different from urban sites. Surface snow ion concentrations on elevation transects in and adjacent to Salt Lake City varied with temporal and spatial trends in aerosol concentrations, increasing following exposure to particulate-rich air as cold air pools developed, and peaking at intermediate elevations (1500-1600 m above sea level, or 200-300 m above the valley floor). Elevation trends in ion concentrations, especially NH4+ and NO3-, corresponded with patterns of aerosol exposure inferred from laser ceilometer data, suggesting that high particulate matter concentrations stimulated fog or dry ion deposition to snow-covered surfaces at the top of the cold air pools. Fog/dry deposition inputs were similar to wet deposition at mid-elevation montane sites, but appeared negligible at lower and higher-elevation sites. Overall, snow ion concentrations in our urban and adjacent montane sites exceeded many values reported from urban precipitation in North America, and greatly exceeded those reported for remote snowpacks. Sodium, Cl-, NH4+, and NO3- concentrations in fresh snow were high relative to previously measured urban precipitation, with means

  1. Results of the California Healthy Homes Indoor Air Quality Study of 2011-2013: Impact of natural gas appliances on air pollutant concentrations

    SciTech Connect

    Mullen, Nasim A.; Li, Jina; Russell, Marion L.; Spears, Michael; Less, Brennan D.; Singer, Brett C.

    2015-03-17

    This study was conducted to assess the current impact of natural gas appliances on air quality in California homes. Data were collected via telephone interviews and measurements inside and outside of 352 homes. Passive samplers measured time-resolved CO and time-integrated NOX, NO2, formaldehyde, and acetaldehyde over ~6d periods in November 2011 - April 2012 and October 2012 - March 2013. The fraction of indoor NOX and NO2 attributable to indoor sources was estimated. NOX, NO2 and highest 1-h CO were higher in homes that cooked with gas and increased with amount of gas cooking. NOX and NO2 were higher in homes with cooktop pilot burners, relative to gas cooking without pilots. Homes with a pilot burner on a floor or wall furnace had higher kitchen and bedroom NOX and NO2 compared to homes without a furnace pilot. When scaled to account for varying home size and mixing volume, indoor-attributed bedroom and kitchen NOX and kitchen NO2 were not higher in homes with wall or floor furnace pilot burners, though bedroom NO2 was higher. In homes that cooked 4 h or more with gas, self-reported use of kitchen exhaust was associated with lower NOX, NO2 and highest 1-h CO. Gas appliances were not associated with higher concentrations of formaldehyde or acetaldehyde.

  2. Phase relations in the system Fe-Si determined in an internally-resistive heated DAC

    NASA Astrophysics Data System (ADS)

    Komabayashi, T.; Antonangeli, D.; Morard, G.; Sinmyo, R.; Mezouar, N.

    2015-12-01

    It is believed that the iron-rich Earth's core contains some amounts of light elements on the basis of the density deficit of 7 % compared to pure iron. The identification of the kinds and amounts of the light elements in the core places constraints on the origin, formation, and evolution of the Earth because dissolution of light elements into an iron-rich core should place important constraints on the thermodynamic conditions (pressure (P), temperature (T), and oxygen fugacity) of the equilibration between liquid silicate and liquid iron during the core formation. Among potential light elements, silicon has been attracting attentions because it is abundant in the mantle, partitioned into both solid and liquid irons, and very sensitive to the oxygen fugacity. An important phase relation in iron alloy is a transition between the face-centred cubic (FCC) structure and hexagonal close-packed (HCP) structure. This boundary is a key to infer the stable structure in the inner core and is used to derive thermodynamic properties of the phases (Komabayashi, 2014). In the Fe-Si system, previous reports were based on experiments in laser-heated diamond anvil cells (DAC), which might have included large termperature uncertainties. We have revisited this boundary in the system Fe-Si using an internally resistive-heated DAC combined with synchrotron X-ray diffraction at the beamline ID27, ESRF. The internally-heated DAC (Komabayashi et al., 2009; 2012) provides much more stable heating than the laser-heated DAC and much higher temperature than externally resistive-heated DAC, which enables us to place tight constraints on the P-T locations of the boundaries. Also because the minimum measurable temperature is as low as 1000 K due to the stable electric heating, the internal heating is able to examine the low temperature phase stability which was not studied by the previous studies. We will report the P-T locations of the boundaries and evaluate the effect of Si on the phase

  3. The Concentration and Distribution of Depleted Uranium (DU) and Beryllium (Be) in Soil and Air on Illeginni Island at Kwajalein Atoll

    SciTech Connect

    Robison, W L; Hamilton, T F; Martinelli, R E; Gouveia, F J; Lindman, T R; Yakuma, S C

    2006-04-27

    Re-entry vehicles on missiles launched at Vandenberg Air Force base in California re-enter at the Western Test Range, the Regan Test Site (RTS) at Kwajalein Atoll. An environmental Assessment (EA) was written at the beginning of the program to assess potential impact of Depleted Uranium (DU) and Beryllium (Be), the major RV materials of interest from a health and environmental perspective. The chemical and structural form of DU and Be in RVs is such that they are insoluble in soil water and sea water. Consequently, residual concentrations of DU and Be observed in soil on the island are not expected to be toxic to plant life because there is essentially no soil to plant uptake. Similarly, due to their insolubility in sea water there is no uptake of either element by marine biota including fish, mollusks, shellfish and sea mammals. No increase in either element has been observed in sea life around Illeginni Island where deposition of DU and Be has occurred. The critical terrestrial exposure pathway for U and Be is inhalation. Concentration of both elements in air over the test period (1989 to 2006) is lower by a factor of 10,000 than the most restrictive U.S. guideline for the general public. Uranium concentrations in air are also lower by factors of 10 to 100 than concentrations of U in air in the U.S. measured by the EPA (Keith et al., 1999). U and Be concentrations in air downwind of deposition areas on Illeginni Island are essentially indistinguishable from natural background concentrations of U in air at the atolls. Thus, there are no health related issues associated with people using the island.

  4. Determining the long-term effects of H₂S concentration, relative humidity and air temperature on concrete sewer corrosion.

    PubMed

    Jiang, Guangming; Keller, Jurg; Bond, Philip L

    2014-11-15

    Many studies of sewer corrosion are performed in accelerated conditions that are not representing the actual corrosion processes. This study investigated the effects of various factors over 3.5 years under controlled conditions simulating the sewer environment. Concrete coupons prepared from precorroded sewers were exposed, both in the gas phase and partially submerged in wastewater, in laboratory controlled corrosion chambers. Over the 45 month exposure period, three environmental factors of H2S concentration, relative humidity and air temperature were controlled at different levels in the corrosion chambers. A total of 36 exposure conditions were investigated to determine the long term effects of these factors by regular retrieval of concrete coupons for detailed analysis of surface pH, corrosion layer sulfate levels and concrete loss. Corrosion rates were also determined for different exposure periods. It was found that the corrosion rate of both gas-phase and partially-submerged coupons was positively correlated with the H2S concentration in the gas phase. Relative humidity played also a role for the corrosion activity of the gas-phase coupons. However, the partially-submerged coupons were not affected by humidity as the surfaces of these coupons were saturated due to capillary suction of sewage on the coupon surface. The effect of temperature on corrosion activity varied and possibly the acclimation of corrosion-inducing microbes to temperature mitigated effects of that factor. It was apparent that biological sulfide oxidation was not the limiting step of the overall corrosion process. These findings provide real insights into the long-term effects of these key environmental factors on the sewer corrosion processes.

  5. Comparing three vegetation monoterpene emission models to measured gas concentrations with a model of meteorology, air chemistry and chemical transport

    NASA Astrophysics Data System (ADS)

    Smolander, S.; He, Q.; Mogensen, D.; Zhou, L.; Bäck, J.; Ruuskanen, T.; Noe, S.; Guenther, A.; Aaltonen, H.; Kulmala, M.; Boy, M.

    2014-10-01

    Biogenic volatile organic compounds (BVOCs) are essential in atmospheric chemistry because of their chemical reactions that produce and destroy tropospheric ozone, their effects on aerosol formation and growth, and their potential influence on global warming. As one of the important BVOC groups, monoterpenes have been a focus of scientific attention in atmospheric research. Detailed regional measurements and model estimates are needed to study emission potential and the monoterpene budget on a global scale. Since the use of empirical measurements for upscaling is limited by many physical and biological factors, such as genetic variation, temperature and light, water availability, seasonal changes, and environmental stresses, comprehensive inventories over larger areas are difficult to obtain. We applied the boundary-layer-chemistry-transport model SOSA (model to Simulate the concentrations of Organic vapours and Sulphuric Acid) to investigate Scots pine (Pinus sylvestris) monoterpene emissions in a boreal coniferous forest at the SMEAR (Station for Measuring forest Ecosystem-Atmosphere Relations) II site, southern Finland. SOSA was applied to simulate monoterpene emissions with three different emission modules: the semiempirical G95, MEGAN (Model of Emissions of Gases and Aerosols from Nature) 2.04 with improved descriptions of temperature and light responses and including also carbonyl emissions, and a process-based model SIM-BIM (Seasonal Isoprenoid synthase Model - Biochemical Isoprenoid biosynthesis Model). For the first time, the emission models included seasonal and diurnal variations in both quantity and chemical species of emitted monoterpenes, based on parameterizations obtained from field measurements. Results indicate that modelling and observations agreed reasonably well and that the model can be used for investigating regional air chemistry questions related to monoterpenes. The predominant modelled monoterpene concentrations, α-pinene and Δ3-carene

  6. Short-Term Fluctuations in Air Pollution and Asthma in Scania, Sweden. Is the Association Modified by Long-Term Concentrations?

    PubMed Central

    Stroh, Emilie; Åström, Daniel Oudin; Jakobsson, Kristina; Oudin, Anna

    2016-01-01

    Background and aims Asthma is one of the most common respiratory diseases in the world. Research has shown that temporal increases in air pollution concentrations can aggravate asthma symptoms. The aim of this study was to assess whether individuals living in areas with higher air pollution concentrations responded differently to short-term temporal exposure to air pollution than those living in lower air pollution areas. Method The study was designed as a case-crossover study in Scania, Sweden. Outcome data was visits to primary health care clinics with asthma as the main complaint during the years 2007 to 2010. Nitrogen dioxide levels were obtained from 21 different air pollution monitoring stations. Short-term exposure was defined as the average concentration four days prior to the visit. Data was pooled for areas above and below a two-year average NO2 concentration of 10 μg/m3, dispersion modelled with an emission database. Results The short-term association between NO2 and asthma visits seemed stronger in areas with NO2 levels below 10 μg/m3, with an odds ratio (OR) of 1.15 (95% confidence interval (CI): 1.08–1.23) associated with a 10 μg/m3 increase in NO2 compared to areas above 10 μg/m3 NO2 levels, where corresponding OR of 1.09 (95% CI: 1.02–1.17). However, this difference was not statistically significant. (p = 0.13) Conclusions The study provided some evidence, although not statistically significant, that short-term associations between air pollution and asthma may depend on background air pollution levels. However, we cannot rule out that the association is due to other spatially dependent factors in Scania. The study should be reproduced in other study areas. PMID:27861543

  7. Comparing three vegetation monoterpene emission models to measured gas concentrations with a model of meteorology, air chemistry and chemical transport

    NASA Astrophysics Data System (ADS)

    Smolander, S.; He, Q.; Mogensen, D.; Zhou, L.; Bäck, J.; Ruuskanen, T.; Noe, S.; Guenther, A.; Aaltonen, H.; Kulmala, M.; Boy, M.

    2013-11-01

    Biogenic volatile organic compounds (BVOCs) are essential in atmospheric chemistry because of their chemical reactions that produce and destroy tropospheric ozone, their effects on aerosol formation and growth, and their potential influence on global warming. As one of the important BVOC groups, monoterpenes have been a focus of scientific attention in atmospheric research. Detailed regional measurements and model estimates are needed to study emission potential and the monoterpene budget on a global scale. Since the use of empirical measurements for upscaling is limited by many physical and biological factors such as genetic variation, temperature and light, water availability, seasonal changes, and environmental stresses, comprehensive inventories over larger areas are difficult to obtain. We applied the boundary layer-chemistry-transport model SOSA to investigate Scots pine (Pinus sylvestris) monoterpene emissions in a boreal coniferous forest at the SMEAR II site, Southern Finland. SOSA was applied to simulate monoterpene emissions with three different emission modules: the semi-empirical G95, MEGAN 2.04 with improved descriptions of temperature and light responses and including also carbonyl emissions, and a process-based model SIM-BIM. For the first time, the emission models included seasonal and diurnal variations in both quantity and chemical species of emitted monoterpenes, based on parameterizations obtained from field measurements. Results indicate that modelling and observations agreed reasonably well, and that the model can be used for investigating regional air chemistry questions related to monoterpenes. The predominant modelled monoterpene concentrations, α-pinene and Δ3-carene, are consistent with observations.

  8. The Effect of Isotopic Composition on the Uncertainty of Routine Metal Mass Concentration Measurements in Ambient Air

    PubMed Central

    Brown, Richard J. C.; Goddard, Sharon L.; Brown, Andrew S.; Yardley, Rachel E.

    2008-01-01

    The main sources of uncertainty encountered during the analysis of the mass concentration of metals in ambient air as part of the operation of the UK Heavy Metals Monitoring Network are presented. It is observed that the uncertainty contribution from possible variation in the isotopic composition of the sample depends on the element in question, but can be significant (e.g., for Pb, Cd, and Hg). The working curve method for the ICP-MS analysis of metals in solution, with a low resolution, high throughput instrument measuring at one m/z ratio per element, relies on the relative abundance of the isotopes under consideration being the same in both the sample and the calibration solution. Calculation of the uncertainty in this analysis assumes that the isotopic composition variation within the sample and calibration solution is limited to a defined range. Therefore, in order to confirm the validity of this quantification methodology and its uncertainty budget, the isotopic composition of the calibration standards used for quantification has been determined. The results of this analysis are presented here. PMID:19223968

  9. The impact of shipping emissions on air pollution in the greater North Sea region - Part 1: Current emissions and concentrations

    NASA Astrophysics Data System (ADS)

    Aulinger, A.; Matthias, V.; Zeretzke, M.; Bieser, J.; Quante, M.; Backes, A.

    2016-01-01

    The North Sea is one of the areas with the highest ship traffic densities worldwide. At any time, about 3000 ships are sailing its waterways. Previous scientific publications have shown that ships contribute significantly to atmospheric concentrations of NOx, particulate matter and ozone. Especially in the case of particulate matter and ozone, this influence can even be seen in regions far away from the main shipping routes. In order to quantify the effects of North Sea shipping on air quality in its bordering states, it is essential to determine the emissions from shipping as accurately as possible. Within Interreg IVb project Clean North Sea Shipping (CNSS), a bottom-up approach was developed and used to thoroughly compile such an emission inventory for 2011 that served as the base year for the current emission situation. The innovative aspect of this approach was to use load-dependent functions to calculate emissions from the ships' current activities instead of averaged emission factors for the entire range of the engine loads. These functions were applied to ship activities that were derived from hourly records of Automatic Identification System signals together with a database containing the engine characteristics of the vessels that traveled the North Sea in 2011. The emission model yielded ship emissions among others of NOx and SO2 at high temporal and spatial resolution that were subsequently used in a chemistry transport model in order to simulate the impact of the emissions on pollutant concentration levels. The total emissions of nitrogen reached 540 Gg and those of sulfur oxides 123 Gg within the North Sea - including the adjacent western part of the Baltic Sea until 5° W. This was about twice as much of those of a medium-sized industrialized European state like the Netherlands. The relative contribution of ships to, for example, NO2 concentration levels ashore close to the sea can reach up to 25 % in summer and 15 % in winter. Some hundred kilometers

  10. The impact of shipping emissions on air pollution in the Greater North Sea region - Part 1: Current emissions and concentrations

    NASA Astrophysics Data System (ADS)

    Aulinger, A.; Matthias, V.; Zeretzke, M.; Bieser, J.; Quante, M.; Backes, A.

    2015-04-01

    The North Sea is one of the areas with the highest ship traffic densities worldwide. At any time, about 3000 ships are sailing its waterways. Previous scientific publications have shown that ships contribute significantly to atmospheric concentrations of NOx, particulate matter and ozone. Especially in the case of particulate matter and ozone this influence can even be seen in regions far away from the main shipping routes. In order to quantify the effects of North Sea shipping on air quality in its bordering states, it is essential to determine the emissions from shipping as accurately as possible. Within the Interreg IVb project Clean North Sea Shipping (CNSS) a bottom-up approach was developed and used to thoroughly compile such an emission inventory for 2011 that served as the base year for the current emission situation. The innovative aspect of this approach was to use load dependent functions to calculate emissions from the ships' current activities instead of averaged emission factors for the entire range of the engine loads. These functions were applied to ship activities that were derived from hourly records of Automatic Identification System signals together with a data base containing the engine characteristics of the vessels that traveled the North Sea in 2011. The emission model yielded ship emissions among others of NOx and SO2 in high temporal and spatial resolution that were subsequently used in a chemistry transport model in order to simulate the impact of the emissions on pollutant concentration levels. The total emissions of nitrogen reached 540 Gg and of sulfur oxides 123 Gg within the North Sea, which was about twice as much of those of a medium-sized industrialized European state like the Netherlands. The relative contribution of ships to, for example, NO2 concentration levels ashore close to the sea can reach up to 25% in summer and 15% in winter. Some hundred kilometers away from the sea the contribution was about 6% in summer and 4% in

  11. [Pharmacological properties of chitosan-coated dialdehyde cellulose (chitosan DAC), a newly developed oral adsorbent (II). Effect of chitosan DAC on rats with chronic renal failure induced by adriamycin].

    PubMed

    Nagano, N; Yoshimoto, H; Nishitoba, T; Sato, H; Miyata, S; Kusaka, M; Jing, S B; Yamaguchi, T

    1995-08-01

    The effects of chitosan-coated dialdehyde cellulose (Chitosan DAC), a newly developed oral adsorbent of urea and ammonia, were examined in rats with progressive chronic renal failure (CRF) induced by adriamycin. CRF rats induced by repeated injections of adriamycin were fed a diet containing chitosan DAC (5% content) or Kremezin (5% content), an oral charcoal adsorbent (AST-120) under strict paired-feeding for four months. CRF rats that received both a normal diet and Kremezin showed progressive azotemia, hyperphosphatemia, hyperlipidemia, proteinuria, and anemia, and began to die from 9 weeks after feeding started. In contrast, chitosan DAC-treatment showed marked prolongation of the survival period and decreases in blood urea nitrogen, serum creatinine, and serum phosphate. In addition, chitosan DAC-treatment ameliorated anemia in CRF rats, although hyperlipidemia and proteinuria were not improved. Furthermore, fecal weight, fecal water content, fecal nitrogen and fecal sodium were markedly increased, and the apparent protein ratio was decreased in CRF rats fed a diet containing chitosan DAC for 9 weeks. In contrast, none of these effects were observed in CRF rats receiving Kremezin. These observations suggest the further possibility of using oral adsorbent therapy for CRF patients.

  12. The Potential of The Synergy of Sunphotometer and Lidar Data to Validate Vertical Profiles of The Aerosol Mass Concentration Estimated by An Air Quality Model

    NASA Astrophysics Data System (ADS)

    Siomos, N.; Filioglou, M.; Poupkou, A.; Liora, N.; Dimopoulos, S.; Melas, D.; Chaikovsky, A.; Balis, D. S.

    2016-06-01

    Vertical profiles of the aerosol mass concentration derived by the Lidar/Radiometer Inversion Code (LIRIC), that uses combined sunphotometer and lidar data, were used in order to validate the aerosol mass concentration profiles estimated by the air quality model CAMx. Lidar and CIMEL measurements performed at the Laboratory of Atmospheric Physics of the Aristotle University of Thessaloniki, Greece (40.5N, 22.9E) from the period 2013-2014 were used in this study.

  13. Respiratory tract retention of inhaled air pollutants: report 1: mercury absorption by inhaling through the nose and expiring through the mouth at various concentrations

    SciTech Connect

    Kikuo, O.; Saito, H.; Kifune, I.; Ohshina, T.; Fujii, M.; Takizawa, Y.

    1982-01-01

    To study atmospheric mercury absorption in human respiratory passage-ways, mercury in expired air was measured in three different states of breathing: steady breathing, deep breathing and breath held after inspiration. In this study, air containing mercury was inhaled through the nose and expired through the mouth. The concentration of mercury in the exhaled air was determined by the technique of gold-amalgam trapping, heat vaporization, and flameless atomic absorption measurement. The subjects were 13 male adults, aged 25-62 years, and 38 cases were observed. Four different concentrations of mercury, 1-3, 4-6, 10-11, and 20-30 ..mu..g/m/sup 3/ were used, and absorption for each was determined, when the concentration was 1-3 ..mu../m/sup 3/, the absorption was 74-92%, the average being 82.5%. At concentrations of 4-6, 10-11, and 20-30 ..mu../m/sup 3/, the absorption was 76.6-100%, 75.5-99.2%, 70.9-95.9% respectively, and the average was 88.8%, 85.2%, and 87.7% respectively. A slightly higher rate of mercury absorption was observed in deep breathing than in steady breathing, and when expiration was suppressed for some time after inspiration, the rate increased remarkably to 97.4-99.7%. Prolonged retention of inhaled air containing mercury in the respiratory tract is believed to have caused the increased absorption.

  14. CONCENTRATION OF TETRACHLOROETHYLENE IN INDOOR AIR AT A FORMER DRY CLEANER FACILITY AS A FUNCTION OF SUBSURFACE CONTAMINATION: A CASE STUDY

    EPA Science Inventory

    A field study was performed to evaluate indoor air concentrations and vapor intrusion (VI) of tetrachloroethylene (PCE) and other chlorinated solvents at a commercial retail site in Dallas, TX. The building is approximately 40 years old and once housed a dry cleaning operation. R...

  15. Impacts of Hazardous Air Pollutants Emitted from Phosphate Fertilizer Production Plants on their Ambient Concentration Levels in the Tampa Bay Area

    EPA Science Inventory

    The concentrations and distribution of Hazardous Air Pollutants (HAPs) metals emitted from four phosphate fertilizer plants in Central Florida, as well as their environmental and health impacts, were assessed. The dominant HAP metals emitted from the stacks of these plants were M...

  16. A new method for the rapid determination of volatile organic compound breakthrough times for a sorbent at concentrations relevant to indoor air quality.

    PubMed

    Scahill, John; Wolfrum, Edward J; Michener, William E; Bergmann, Michael; Blake, Daniel M; Watt, Andrew S

    2004-01-01

    The use of sorbents has been proposed to remove volatile organic compounds (VOCs) present in ambient air at concentrations in the parts-per-billion (ppb) range, which is typical of indoor air quality applications. Sorbent materials, such as granular activated carbon and molecular sieves, are used to remove VOCs from gas streams in industrial applications, where VOC concentrations are typically in the parts-per-million range. A method for evaluating the VOC removal performance of sorbent materials using toluene concentrations in the ppb range is described. Breakthrough times for toluene at concentrations from 2 to 7500 ppb are presented for a hydrophobic molecular sieve at 25%) relative humidity. By increasing the ratio of challenge gas flow rate to the mass of the sorbent bed and decreasing both the mass of sorbent in the bed and the sorbent particle size, this method reduces the required experimental times by a factor of up to several hundred compared with the proposed American Society of Heating, Refrigerating, and Air-Conditioning Engineers method, ASHRAE 145P, making sorbent performance evaluation for ppb-range VOC removal more convenient. The method can be applied to screen sorbent materials for application in the removal of VOCs from indoor air.

  17. Coupling lead isotopes and element concentrations in epiphytic lichens to track sources of air emissions in the Alberta Oil Sands Region

    EPA Science Inventory

    A study was conducted that coupled use of element concentrations and lead (Pb) isotope ratios in the lichen Hypogymnia physodes collected during 2002 and 2008, to assess the impacts of air emissions from the Alberta Oil Sands Region (AOSR, Canada) mining and processing operations...

  18. Pore structure and dielectric behaviour of the 3D collagen-DAC scaffolds designed for nerve tissue repair.

    PubMed

    Pietrucha, Krystyna; Marzec, Ewa; Kudzin, Marcin

    2016-11-01

    The design and selection of a suitable scaffold with well-defined pores size distribution and dielectric properties are critical features for neural tissue engineering. In this study we use mercury porosimetry and the dielectric spectroscopy in the alpha-dispersion region of the electric field to determine the microarchitecture and activation energy of collagen (Col) modified by 2,3 dialdehyde cellulose (DAC). The scaffold was synthesized in three steps: (i) preparation of DAC by oxidation of cellulose, (ii) construction of a 3D Col sponge-shape or film, (iii) cross-linkage of the Col samples using DAC. The activation energy needed to break the bonds formed by water in the Col-DAC composite is approximately 2 times lower than that in the unmodified Col. In addition, the magnitude of conductivity for modified Col at 70°C is approximately 40% lower than that recorded for the unmodified Col. The largest fraction, of which at least 70% of the total pore volume comprises the sponge, is occupied by pores ranging from 20 to 100μm in size. The knowledge on the dielectric behaviour and microstructure of the Col-DAC scaffold may prove relevant to neural tissue engineering focused on the regeneration of the nervous system.

  19. Computer system requirements specification for 101-SY hydrogen mitigation test project data acquisition and control system (DACS-1)

    SciTech Connect

    McNeece, S.G.; Truitt, R.W.

    1994-10-12

    The system requirements specification for SY-101 hydrogen mitigation test project (HMTP) data acquisition and control system (DACS-1) documents the system requirements for the DACS-1 project. The purpose of the DACS is to provide data acquisition and control capabilities for the hydrogen mitigation testing of Tank SY-101. Mitigation testing uses a pump immersed in the waste, directed at varying angles and operated at different speeds and time durations. Tank and supporting instrumentation is brought into the DACS to monitor the status of the tank and to provide information on the effectiveness of the mitigation test. Instrumentation is also provided for closed loop control of the pump operation. DACS is also capable for being expanded to control and monitor other mitigation testing. The intended audience for the computer system requirements specification includes the SY-101 hydrogen mitigation test data acquisition and control system designers: analysts, programmers, instrument engineers, operators, maintainers. It is intended for the data users: tank farm operations, mitigation test engineers, the Test Review Group (TRG), data management support staff, data analysis, Hanford data stewards, and external reviewers.

  20. Background air concentrations of Cr(VI) in Hudson County, New Jersey: implications for setting health-based standards for Cr(VI) in soil.

    PubMed

    Scott, P K; Finley, B L; Harris, M A; Rabbe, D E

    1997-05-01

    An accurate measure of "background" airborne Cr(VI) concentrations will be necessary to derive site-specific health-based Cr(VI) soil concentrations at sites containing chromite ore processing residues (COPR) in Hudson County, NJ. To date, no such data have been collected in New Jersey. This paper describes an air sampling program designed to measure background concentrations of Cr(VI) in Hudson County and compare those concentrations with the air sampling results obtained previously at 30 COPR sites in Hudson County. Background airborne Cr(VI) concentrations ranged from 0.2 to 3.8 ng/m3 with an arithmetic mean of 1.2 ng/m3. Comparisons of the airborne Cr(VI) concentrations previously measured at 30 COPR sites indicated that more than two-thirds of the sites had mean airborne Cr(VI) concentrations that were not statistically significantly greater than background. Our findings suggest that, in general, vehicle disturbance is required for significant soil suspension to occur at these sites. Since airborne Cr(VI) concentrations at many of these sites are close to background, it is critical that background airborne Cr(VI) levels be considered when deriving health-based soil standards at the COPR sites.

  1. Simulation of Regional-scale Nucleation Events and Prediction of Aerosol Number Concentration in a Regional Air Quality Model

    NASA Astrophysics Data System (ADS)

    Jung, J.; Adams, P.; Pandis, S.

    2006-12-01

    Nanoparticles can perturb Earth's climate by growing to cloud condensation nuclei sizes and also may be harmful to human health. Accurate simulation of the nucleation, growth, and removal of multicomponent nanoparticles demands enormous computational resources. Most regional-scale three-dimensional chemical transport models do not include nanoparticles and do not conserve number concentrations. A major challenge associated with the simulation of nucleation events is the uncertainty regarding the controlling nucleation mechanism under typical atmospheric conditions. Previous work indicates that nucleation events in the Pittsburgh area are well predicted using ternary (H2O-H2SO4-NH3) nucleation theory, which was successful in predicting on which days nucleation events occurred during summer and winter, as well as the beginning and end of the events. To predict the composition and growth of nanoparticles, we have developed a computationally efficient new approach based on the Two-Moment Aerosol Sectional (TOMAS) microphysics module. This model simulates inorganic and organic components of the nanoparticles describing both the number and the mass distribution of the particulate matter from approximately 1 nm to 10 micrometers. The model explains why nanoparticles were observed to be acidic during nucleation events that appear to involve ammonia. The simulation suggests that nanoparticles produced by ternary nucleation can be acidic due to depletion of ammonia vapor during the growth of the particles out of the nucleation sizes. The low CPU time requirements of the model using TOMAS make it suitable for incorporation in three- dimensional chemical transport models. The nucleation/coagulation/growth model has been added to the PMCAMx regional air quality model and is used for the investigation of nucleation events in the Eastern U.S. We can estimate number budget in the Eastern U.S. and predict frequency/size of nucleation events.

  2. Transport of semivolatile organic compounds to the Tibetan plateau: spatial and temporal variation in air concentrations in mountainous Western Sichuan, China.

    PubMed

    Liu, Wenjie; Chen, Dazhou; Liu, Xiande; Zheng, Xiaoyan; Yang, Wen; Westgate, John N; Wania, Frank

    2010-03-01

    The distribution of organochlorine pesticides and polychlorinated biphenyls in air along an altitudinal transect on Balang Mountain in western China was measured by deploying XAD-2 resin based passive air samplers in duplicate at seven sites with elevations ranging from 1242 to 4485 m above sea level for five consecutive six-month periods between 2005 and 2008. Analyzed by gas chromatography-high resolution mass spectrometry, concentrations of hexachlorobenzene were highest, followed by hexachlorocyclohexanes, DDT-related compounds and PCB congeners 28 and 52. Except for hexachlorobenzene, which had largely uniform concentrations in space and time, there were clear seasonal variations with concentrations in summer being higher than in winter. With a few exceptions, concentrations that vary little with altitude suggest that the presence of these chemicals in the area is almost entirely due to atmospheric transport, most likely from the Chengdu plain. This is supported by similarities in the relative abundance of different compounds and in the differences between summer and winter concentrations measured in the city of Chengdu and in the mountains. Furthermore, air mass trajectories during the sampling period often originate to the East, passing over the Western part of the Sichuan basin, including the Chengdu plain, prior to arriving at the sampling sites. Higher summer time values in the mountains are due to more contaminated air being blown into the region, presumably due either to higher pesticide usage in summer or due to higher temperatures leading to higher evaporation in source regions. Air and soil from the region are in equilibrium with respect to alpha-HCH, gamma-HCH, and HCB, whereas a situation of net deposition prevails for p,p'-DDE and p,p'-DDT.

  3. Intercomparison of air quality data using principal component analysis, and forecasting of PM₁₀ and PM₂.₅ concentrations using artificial neural networks, in Thessaloniki and Helsinki.

    PubMed

    Voukantsis, Dimitris; Karatzas, Kostas; Kukkonen, Jaakko; Räsänen, Teemu; Karppinen, Ari; Kolehmainen, Mikko

    2011-03-01

    In this paper we propose a methodology consisting of specific computational intelligence methods, i.e. principal component analysis and artificial neural networks, in order to inter-compare air quality and meteorological data, and to forecast the concentration levels for environmental parameters of interest (air pollutants). We demonstrate these methods to data monitored in the urban areas of Thessaloniki and Helsinki in Greece and Finland, respectively. For this purpose, we applied the principal component analysis method in order to inter-compare the patterns of air pollution in the two selected cities. Then, we proceeded with the development of air quality forecasting models for both studied areas. On this basis, we formulated and employed a novel hybrid scheme in the selection process of input variables for the forecasting models, involving a combination of linear regression and artificial neural networks (multi-layer perceptron) models. The latter ones were used for the forecasting of the daily mean concentrations of PM₁₀ and PM₂.₅ for the next day. Results demonstrated an index of agreement between measured and modelled daily averaged PM₁₀ concentrations, between 0.80 and 0.85, while the kappa index for the forecasting of the daily averaged PM₁₀ concentrations reached 60% for both cities. Compared with previous corresponding studies, these statistical parameters indicate an improved performance of air quality parameters forecasting. It was also found that the performance of the models for the forecasting of the daily mean concentrations of PM₁₀ was not substantially different for both cities, despite the major differences of the two urban environments under consideration.

  4. Meta-Analysis on Near-Road Air Pollutants Concentrations for Developing Traffic Indicators for Exposure Assessment

    EPA Science Inventory

    Near-road air pollution has been associated with various health risks in human populations living near roadways. To better understand relationship between vehicle emissions and spatial profiles of traffic-related air pollutants we performed a comprehensive and systematic literat...

  5. NEIGHBORHOOD SCALE MODELING OF PM 2.5 AND AIR TOXICS CONCENTRATION DISTRIBUTIONS TO DRIVE HUMAN EXPOSURE MODELS

    EPA Science Inventory

    Air quality (AQ) simulation models provide a basis for implementing the National Ambient Air Quality Standards (NAAQS) and are a tool for performing risk-based assessments and for developing environmental management strategies. Fine particulate matter (PM 2.5), its constituent...

  6. Pulse oximeter improvement with an ADC-DAC feedback loop and a radial reflectance sensor.

    PubMed

    Thompson, David; Wareing, Austin; Day, Dwight; Warren, Steve

    2006-01-01

    Pulse oximeter circuitry must meet several design constraints, including the ability to separate a small pulsatile signal component from a large signal baseline. This paper describes pulse oximeter design changes that produced order-of-magnitude improvements in signal quality. The primary changes were (a) the replacement of an analog sample-and-hold-based differentiator circuit with an ADC-DAC feedback loop and (b) the replacement of a side-by-side reflectance sensor design with a radial sensor arrangement that maximizes the pulsatile-to-baseline signal ratio.

  7. Evaluation of Ultra-Violet Photocatalytic Oxidation (UVPCO) forIndoor Air Applications: Conversion of Volatile Organic Compounds at LowPart-per-Billion Concentrations

    SciTech Connect

    Hodgson, Alfred T.; Sullivan, Douglas P.; Fisk, William J.

    2005-09-30

    Efficient removal of indoor generated airborne particles and volatile organic compounds (VOCs) in office buildings and other large buildings may allow for a reduction in outdoor air supply rates with concomitant energy savings while still maintaining acceptable indoor air quality in these buildings. Ultra-Violet Photocatalytic Oxidation (UVPCO) air cleaners have the potential to achieve the necessary reductions in indoor VOC concentrations at relatively low cost. In this study, laboratory experiments were conducted with a scaled, prototype UVPCO device designed for use in a duct system. The experimental UVPCO contained two 30 by 30-cm honeycomb monoliths coated with titanium dioxide and 3% by weight tungsten oxide. The monoliths were irradiated with 12 UVC lamps arranged in four banks. The UVPCO was challenged with four mixtures of VOCs typical of mixtures encountered in indoor air. A synthetic office mixture contained 27 VOCs commonly measured in office buildings. A cleaning product mixture contained three cleaning products with high market shares. A building product mixture was created by combining sources including painted wallboard, composite wood products, carpet systems, and vinyl flooring. A fourth mixture contained formaldehyde and acetaldehyde. Steady-state concentrations were produced in a classroom laboratory or a 20-m{sup 3} environmental chamber. Air was drawn through the UVPCO, and single pass conversion efficiencies were measured from replicate air samples collected upstream and downstream of the reactor section. Concentrations of the mixtures were manipulated, with concentrations of individual VOCs mostly maintained below 10 ppb. Device flow rates were varied between 165 and 580 m{sup 3}/h. Production of formaldehyde, acetaldehyde, acetone, formic acid, and acetic acid as reaction products was investigated. Conversion efficiency data were generated for 48 individual VOCs or groups of closely related compounds. Alcohols and glycol ethers were the

  8. Concentration of tetrachloroethylene in indoor air at a former dry cleaner facility as a function of subsurface contamination: a case study.

    PubMed

    Eklund, Bart M; Simon, Michelle A

    2007-06-01

    A field study was performed to evaluate indoor air concentrations and vapor intrusion (VI) of tetrachloroethylene (PCE) and other chlorinated solvents at a commercial retail site in Dallas, TX. The building is approximately 40 yr old and once housed a dry cleaning operation. Results from an initial site characterization were used to select sampling locations for the VI study. The general approach for evaluating VI was to collect time-integrated canister samples for off-site U.S. Environmental Protection Agency Method TO-15 analyses. PCE and other chlorinated solvents were measured in shallow soil gas, subslab soil-gas, indoor air, and ambient air. The subslab soil gas exhibited relatively high values: PCE < or =2,600,000 parts per billion by volume (ppbv) and trichloroethylene < or =170 ppbv. The attenuation factor, the ratio of indoor air and subslab soil-gas concentrations, was unusually low: approximately 5 x 10(-6) based on the maximum subslab soil-gas concentration of PCE and 1.4 x 10(-5) based on average values.

  9. Influence of air-staging on the concentration profiles of NH{sub 3} and HCN in the combustion chamber of a CFB boiler burning coal

    SciTech Connect

    Kassman, H.; Karlsson, M.; Aamand, L.E.

    1999-07-01

    The characterization of the concentration profiles of NH{sub 3} and HCN are of great importance for increasing the knowledge of the formation and destruction pathways of NO and N{sub 2}O in a fluidized bed boiler. Further improvements of the sampling methods for the determination of both NH{sub 3} and HCN in the combustion chamber in full-scale CFB boilers are also needed. A gas-sampling probe connected to a Fourier Transform Infrared (FTIR) instrument and a gas-quenching (GQ) probe in which the sample is quenched directly in the probe tip by a circulating trapper solution were used. The FTIR technique is based on analysis of hot combustion gases, whereas the trapper solutions from the GQ probe were analyzed by means of wet chemistry. The tests were performed during coal combustion in a 12 MW CFB boiler, which was operated at three air-staging cases with the addition of limestone for sulfur capture. The concentration profiles of NH{sub 3} and HCN in the combustion chamber showed a different pattern concerning the influence of air-staging. The highest levels of NH{sub 3} were observed during reducing condition (severe air-staging), and the lowest were found under oxidizing conditions (no air-staging). The levels of HCN were much lower than those measured for NH{sub 3}. The highest levels of HCN were observed for reversed air-staging and severe air-staging showed almost no HCN. The potential reactors involving NH{sub 3} and HCN in the combustion chamber as well as the potential measurement errors in each sampling technique are discussed for the three air-staging cases.

  10. Ambient Air Radionuclide Concentrations at and near TA-50 from 2003 through the First Quarter of 2004

    SciTech Connect

    K.W. Jacobson; C.F. Eberhart

    2005-09-05

    The Meteorology and Air Quality (MAQ) group at Los Alamos National Laboratory maintains and operates a large network of environmental air samplers called AIRNET. Some of these samplers are located near Material Disposal Area C at TA-50, a low-level radioactive waste burial site in the semiarid environment of the Pajarito Plateau, near Los Alamos. AIRNET sampling media consist of a filter and silica gel. They are exchanged once every 2 weeks. Presented are 5 months of air sampling results for 5 stations operating in the vicinity of Material Disposal Area C.

  11. Exploring EKC, trends of growth patterns and air pollutants concentration level in Malaysia: A Nemerow Index Approach

    NASA Astrophysics Data System (ADS)

    Bekhet, Hussain A.; >Tahira Yasmin,

    2013-06-01

    The present study examines an Environmental Kuznets Curve (EKC) hypothesis by analyzing annual data of air pollutants concentartion and per capita GDP as economic indicator over the (1996-2010) period in Malaysia. Nemerow Index Approach (I) used to generate a measures of air pollution. The results show that ambient air quality indicators supports the EKC hypothesis which stated that pollution levels increase as a country develops, but begin to decrease as rising incomes pass beyond a turning poin. Also, the I result is justifying that most pollutants are showing value less than 1.

  12. Observational study on the concentration distributions of SO{sub 2} and NO{sub 2} in Dhaka, Bangladesh under severe air pollution condition in winter

    SciTech Connect

    Azad, A.K.; Kitada, T.

    1996-12-31

    Dhaka is the capital and the biggest city of Bangladesh, and is expanding very rapidly. Emissions from heavy traffic and many small industries and commercial complexes, newly developed in and around the city, are polluting the air of Dhaka city. The air pollution is severe especially in winter due to adverse meteorological conditions such as low wind speed and dry, stably-stratified air, which restricts the mixing height to low levels and prevent dispersion of pollutants. But so far no study of air pollution of Dhaka city has been done. We have first measured SO{sub 2} and NO{sub 2} concentrations in Dhaka city in a large scale and derived their spatial distributions over Dhaka. Molecular diffusion tubes, which do not require power sources and are produced at low cost, have been used to measure the concentration distributions of SO{sub 2} and NO{sub 2} at 64 sites in Dhaka city and its suburbs during the period of December-January of 1995-96. The diffusion tube samplers were calibrated using 6 automated air pollution monitoring stations in Aichi-prefecture, Japan. The calibration curve and the distribution of the concentration data acquired by automatic measurement instrument at each location showed that the error range of measurements with the molecular diffusion tube samplers was 2-27%. The samples were analyzed using ion-chromatography and spectrophotometer to determine the concentrations of SO{sub 2} and NO{sub 2} respectively. The contamination of unexposed tubes under field conditions was determined and the value of the blank test was subtracted from the measurements of the diffusion tube samplers. The effects of wind turbulence and temperature were reduced using polyflon filters.

  13. Polyurethane foam (PUF) disk passive samplers derived polychlorinated biphenyls (PCBs) concentrations in the ambient air of Bursa-Turkey: Spatial and temporal variations and health risk assessment.

    PubMed

    Birgül, Aşkın; Kurt-Karakus, Perihan Binnur; Alegria, Henry; Gungormus, Elif; Celik, Halil; Cicek, Tugba; Güven, Emine Can

    2017-02-01

    Polyurethane foam (PUF) passive samplers were employed to assess air concentrations of polychlorinated biphenyls (PCBs) in background, agricultural, semi-urban, urban and industrial sites in Bursa, Turkey. Samplers were deployed for approximately 2-month periods from February to December 2014 in five sampling campaign. Results showed a clear rural-agricultural-semi-urban-urban-industrial PCBs concentration gradient. Considering all sampling periods, ambient air concentrations of Σ43PCBs ranged from 9.6 to 1240 pg/m(3) at all sites with an average of 24.1 ± 8.2, 43.8 ± 24.4, 140 ± 190, 42.8 ± 24.6, 160 ± 280, 84.1 ± 105, 170 ± 150 and 280 ± 540 pg/m(3) for Mount Uludag, Uludag University Campus, Camlica, Bursa Technical University Osmangazi Campus, Hamitler, Agakoy, Kestel Organised Industrial District and Demirtas Organised Industrial District sampling sites, respectively. The ambient air PCB concentrations increased along a gradient from background to industrial areas by a factor of 1.7-11.4. 4-Cl PCBs (31.50-81.60%) was the most dominant homologue group at all sampling sites followed by 3-Cl, 7-Cl, 6-Cl and 5-Cl homologue groups. Sampling locations and potential sources grouped in principal component analysis. Results of PCA plots highlighted a large variability of the PCB mixture in air, hence possible related sources, in Bursa area. Calculated inhalation risk levels in this study indicated no serious adverse health effects. This study is one of few efforts to characterize PCB composition in ambient air seasonally and spatially for urban and industrial areas of Turkey by using passive samplers as an alternative sampling method for concurrent monitoring at multiple sites.

  14. Distribution automation and control support; Analysis and interpretation of DAC working group results for use in project planning

    NASA Technical Reports Server (NTRS)

    Klock, P.; Evans, D.

    1979-01-01

    The Executive Summary and Proceedings of the Working Group Meeting was analyzed to identify specific projects appropriate for Distribution Automation and Control DAC RD&D. Specific projects that should be undertaken in the DAC RD&D program were recommended. The projects are presented under broad categories of work selected based on ESC's interpretation of the results of the Working Group Meeting. Some of the projects are noted as utility industry projects. The ESC recommendations regarding program management are presented. Utility versus Government management responsibilities are noted.

  15. A Method for Estimating Urban Background Concentrations in Support of Hybrid Air Pollution Modeling for Environmental Health Studies

    EPA Science Inventory

    Exposure studies rely on detailed characterization of air quality, either from sparsely located routine ambient monitors or from central monitoring sites that may lack spatial representativeness. Alternatively, some studies use models of various complexities to characterize local...

  16. Summary and results of the joint WMD-DAC/Alameda County bioterrorism response plan exercise.

    SciTech Connect

    Manley, Dawn Kataoka; Lipkin, Joel; West, Todd H.; Tam, Ricky; Hirano, Howard H.; Ammerlahn, Heidi R.

    2003-11-01

    On June 12,2003, the Alameda County Public Health Department and Sandia National Laboratories/CA jointly conducted an exercise that used a Weapons of Mass Destruction-Decision Analysis Center (WMD-DAC) bioterrorism attack simulation to test the effectiveness of the county's emergency response plan. The exercise was driven by an assumed release (in the vicinity of the Berkeley Marina), and subsequent spread, of a small quantity of aerosolized, weapons-grade anthrax spores. The simulation used several key WMD-DAC capabilities, namely: (1) integration with an atmospheric dispersion model to calculate expected dose levels in the affected areas, (2) a individual-tracking capability for both infected and non-infected persons as they made decisions, sought treatment, and received prophylaxis drugs, and (3) a user interface that allows exercise participants to affect the scenario evolution and outcome. The analysis of the county's response plan included documenting and reviewing the decisions made by participants during the exercise. Twenty-six local and regional officials representing the health care system, emergency medical services and law enforcement were involved in responding to the simulated attack. The results of this joint effort include lessons learned both by the Alameda County officials regarding implementation of their bioterrorism response plan and by the Sandia representatives about conducting exercises of this type. These observations are reviewed in this report, and they form a basis for providing a better understanding of group/individual decision processes and for identifying effective communication options among decision makers.

  17. Performance Engineering Research Institute SciDAC-2 Enabling Technologies Institute Final Report

    SciTech Connect

    Hall, Mary

    2014-09-19

    Enhancing the performance of SciDAC applications on petascale systems has high priority within DOE SC. As we look to the future, achieving expected levels of performance on high-end com-puting (HEC) systems is growing ever more challenging due to enormous scale, increasing archi-tectural complexity, and increasing application complexity. To address these challenges, PERI has implemented a unified, tripartite research plan encompassing: (1) performance modeling and prediction; (2) automatic performance tuning; and (3) performance engineering of high profile applications. The PERI performance modeling and prediction activity is developing and refining performance models, significantly reducing the cost of collecting the data upon which the models are based, and increasing model fidelity, speed and generality. Our primary research activity is automatic tuning (autotuning) of scientific software. This activity is spurred by the strong user preference for automatic tools and is based on previous successful activities such as ATLAS, which has automatically tuned components of the LAPACK linear algebra library, and other re-cent work on autotuning domain-specific libraries. Our third major component is application en-gagement, to which we are devoting approximately 30% of our effort to work directly with Sci-DAC-2 applications. This last activity not only helps DOE scientists meet their near-term per-formance goals, but also helps keep PERI research focused on the real challenges facing DOE computational scientists as they enter the Petascale Era.

  18. Building a Universal Nuclear Energy Density Functional (UNEDF). SciDAC-2 Project

    SciTech Connect

    Vary, James P.; Carlson, Joe; Furnstahl, Dick; Horoi, Mihai; Lusk, Rusty; Nazarewicz, Witek; Ng, Esmond; Thompson, Ian

    2012-09-29

    An understanding of the properties of atomic nuclei is crucial for a complete nuclear theory, for element formation, for properties of stars, and for present and future energy and defense applications. During the period of Dec. 1 2006 – Jun. 30, 2012, the UNEDF collaboration carried out a comprehensive study of all nuclei, based on the most accurate knowledge of the strong nuclear interaction, the most reliable theoretical approaches, the most advanced algorithms, and extensive computational resources, with a view towards scaling to the petaflop platforms and beyond. Until recently such an undertaking was hard to imagine, and even at the present time such an ambitious endeavor would be far beyond what a single researcher or a traditional research group could carry out. The UNEDF SciDAC project has developed several key computational codes and algorithms for reaching the goal of solving the nuclear quantum many-body problem throughout the chart of nuclei. Without such developments, scientific progress would not be possible. In addition the UNEDF SciDAC successfully applied these developments to solve many forefront research problems.

  19. SciDAC - The Scientific Data Management Center (http://sdmcenter.lbl.gov)

    SciTech Connect

    Ling Liu Calton Pu

    2005-06-20

    In SciDAC SDM project, the main assignment to the Georgia Institute of Technology team (according to the proposed work) is to develop advanced information extraction and information integration technologies on top of the XWRAP technology originated from Georgia Tech [LPH01]. We have developed XWRAPComposer technology to enable the XWRAP code generator to generate Java information wrappers that are capable of extraction of data from multiple linked pages. These information wrappers are used as gateways or adaptors for scientific information mediators to access and fuse interesting data and answering complex queries over a large collection of heterogeneous scientific information sources. Our accomplishments over the SciDAC sponsored years (July 2001 to July 2004) can be summarized along two dimensions. Technically, we have produced a number of major software releases and published over 30 research papers in both international conferences and international journals. The planned software releases include 1. Five Java wrappers and five WDSL-enabled wrappers for SDM Pilot scenarios, which were released in early 2003, 2. The XWRAPComposer toolkit (command line version) which was first released in late 2003 and then released in Summer 2004, 3. Five Ptolemy wrapper actors which were released first in Summer 2003, and then released again in Fall 2005. 4. The decomposable XWRAPComposer actor in Ptolemy, which we have made it available as open source in end of 2004 and tested it in early 2005.

  20. [Concentrations of mercury in ambient air in wastewater irrigated area of Tianjin City and its accumulation in leafy vegetables].

    PubMed

    Zheng, Shun-An; Han, Yun-Lei; Zheng, Xiang-Qun

    2014-11-01

    limit of mercury in food. Spinach appeared to accumulate more mercury than the other four vegetables, in which the median and mean mercury content were both higher than 20 μg x kg(-1). The mercury concentrations in rape, lettuce and allium tuberosum were lower than the standard. Moreover, test results indicated that the Hg content in leafy vegetables was mainly the gaseous mercury through leaf adsorption but not the Hg particulates. This study clearly manifested that there should be a great concern on the pollution risk of both air-and soil borne mercury when cultivating leafy vegetables in long-term wastewater-irrigated area.

  1. Measurements of high surface ozone concentration at Desirade Island: long-range transport of polluted air from North America to Caribe region

    NASA Astrophysics Data System (ADS)

    Molinie, J.; Plocoste, T.; Jacoby-Koaly, S.; Gobinddass, M.; Petit, R.

    2013-05-01

    Desirade island (16.29°N, 61.08°W) is located in the Atlantic Ocean at the extreme East of the lesser Antilles arc (close to Guadeloupe Island). This island can be considered to a rectangle enlarge of 2 km versus 11 km. It is totally rural with few inhabitants (1600), very weak car traffic and no industry. Measures of ozone concentrations were performed from February to March 2005 by the air quality network of Guadeloupe: Gwad'air. High concentrations of ozone (between 22 and 32 ppbv) have been identified during this period of two months. It can't be locally produced because the associated NOx concentrations measured at the same time and at the same position gave us quasi constant levels (close to zero ppbv). To find the ozone origin, we have analyzed the air masses background trajectories calculated by HYSPLIT. Most of them showed on 5 days path trajectories crossing the North American continent before their arrival over Desirade Island. We can consider that this American pollution affects only the Northern part of the Caribbean Islands by observing no local ozone concentrations in the measures from Martinique Island (about 200 km south to our experiment field position).

  2. SciDAC's Earth System Grid Center for Enabling Technologies Semiannual Progress Report October 1, 2010 through March 31, 2011

    SciTech Connect

    Williams, Dean N.

    2011-04-02

    This report summarizes work carried out by the Earth System Grid Center for Enabling Technologies (ESG-CET) from October 1, 2010 through March 31, 2011. It discusses ESG-CET highlights for the reporting period, overall progress, period goals, and collaborations, and lists papers and presentations. To learn more about our project and to find previous reports, please visit the ESG-CET Web sites: http://esg-pcmdi.llnl.gov/ and/or https://wiki.ucar.edu/display/esgcet/Home. This report will be forwarded to managers in the Department of Energy (DOE) Scientific Discovery through Advanced Computing (SciDAC) program and the Office of Biological and Environmental Research (OBER), as well as national and international collaborators and stakeholders (e.g., those involved in the Coupled Model Intercomparison Project, phase 5 (CMIP5) for the Intergovernmental Panel on Climate Change (IPCC) 5th Assessment Report (AR5); the Community Earth System Model (CESM); the Climate Science Computational End Station (CCES); SciDAC II: A Scalable and Extensible Earth System Model for Climate Change Science; the North American Regional Climate Change Assessment Program (NARCCAP); the Atmospheric Radiation Measurement (ARM) program; the National Aeronautics and Space Administration (NASA), the National Oceanic and Atmospheric Administration (NOAA)), and also to researchers working on a variety of other climate model and observation evaluation activities. The ESG-CET executive committee consists of Dean N. Williams, Lawrence Livermore National Laboratory (LLNL); Ian Foster, Argonne National Laboratory (ANL); and Don Middleton, National Center for Atmospheric Research (NCAR). The ESG-CET team is a group of researchers and scientists with diverse domain knowledge, whose home institutions include eight laboratories and two universities: ANL, Los Alamos National Laboratory (LANL), Lawrence Berkeley National Laboratory (LBNL), LLNL, NASA/Jet Propulsion Laboratory (JPL), NCAR, Oak Ridge National

  3. Urinary and air phthalate concentrations and self-reported use of personal care products among minority pregnant women in New York city.

    PubMed

    Just, Allan C; Adibi, Jennifer J; Rundle, Andrew G; Calafat, Antonia M; Camann, David E; Hauser, Russ; Silva, Manori J; Whyatt, Robin M

    2010-11-01

    Diethyl phthalate (DEP) and di-n-butyl phthalate (DnBP) are used extensively in personal care products, including fragrances (DEP) and nail polish (DnBP). Between May 2003 and July 2006, we gathered questionnaire data on the use of seven product categories (deodorant, perfume, hair spray, hair gel, nail polish/polish remover, liquid soap/body wash, and lotion/mist) over 48 h during the third trimester of pregnancy from 186 inner-city women. A 48-h personal air sample was collected and analyzed for DEP and DnBP; a maternal spot urine sample was collected and analyzed for their monoester metabolites, monoethyl phthalate (MEP) and mono-n-butyl phthalate (MnBP), respectively. In all, 97% of air samples and 84% of urine samples were collected within ±2 days of the questionnaire. During the 48 h, 41% of women reported perfume use and 10% reported nail polish/polish remover use. In adjusted analyses, no association was seen between nail product use and air DnBP or urine MnBP concentrations. Women reporting perfume use had 2.3 times higher (95% CI 1.6, 3.3) urinary MEP concentrations. Personal air DEP increased by 7% for each 25% increase in a composite indicator of the six other product categories (P<0.05), but was not associated with perfume use. Air DEP was correlated with urine MEP concentrations only among non-perfume users (r=0.51, P<0.001). Results suggest that perfume use is a significant source of DEP exposure.

  4. Urinary and air phthalate concentrations and self-reported use of personal care products among minority pregnant women in New York City

    PubMed Central

    Just, Allan C.; Adibi, Jennifer J.; Rundle, Andrew G.; Calafat, Antonia M.; Camann, David E.; Hauser, Russ; Silva, Manori J.; Whyatt, Robin M.

    2011-01-01

    Diethyl phthalate (DEP) and di-n-butyl phthalate (DnBP) are used extensively in personal care products, including fragrances (DEP) and nail polish (DnBP). Between May 2003 and July 2006, we gathered questionnaire data on use of 7 product categories (deodorant, perfume, hair spray, hair gel, nail polish/polish remover, liquid soap/body wash, lotion/mist) over 48 hours during the 3rd trimester of pregnancy from 186 inner-city women. A 48-hour personal air sample was collected and analyzed for DEP and DnBP; a maternal spot urine sample was collected and analyzed for their monoester metabolites, monoethyl phthalate (MEP) and mono-n-butyl phthalate (MnBP), respectively. Ninety-seven percent of air samples and 84% of urine samples were collected within ±2 days of the questionnaire. During the 48 hours, 41% of women reported perfume use and 10% reported nail polish/polish remover use. In adjusted analyses, no association was seen between nail product use and air DnBP or urine MnBP concentrations. Women reporting perfume use had 2.3 times higher (95% CI 1.6, 3.3) urinary MEP concentrations. Personal air DEP increased 7% for each 25% increase in a composite indicator of the 6 other product categories (p<0.05) but was not associated with perfume use. Air DEP was correlated with urine MEP concentrations only among non-perfume users (r=0.51, p<0.001). Results suggest that perfume use is a significant source of DEP exposure. PMID:20354564

  5. Changes in Air CO2 Concentration Differentially Alter Transcript Levels of NtAQP1 and NtPIP2;1 Aquaporin Genes in Tobacco Leaves

    PubMed Central

    Secchi, Francesca; Schubert, Andrea; Lovisolo, Claudio

    2016-01-01

    The aquaporin specific control on water versus carbon pathways in leaves is pivotal in controlling gas exchange and leaf hydraulics. We investigated whether Nicotiana tabacum aquaporin 1 (NtAQP1) and Nicotiana tabacum plasma membrane intrinsic protein 2;1 (NtPIP2;1) gene expression varies in tobacco leaves subjected to treatments with different CO2 concentrations (ranging from 0 to 800 ppm), inducing changes in photosynthesis, stomatal regulation and water evaporation from the leaf. Changes in air CO2 concentration ([CO2]) affected net photosynthesis (Pn) and leaf substomatal [CO2] (Ci). Pn was slightly negative at 0 ppm air CO2; it was one-third that of ambient controls at 200 ppm, and not different from controls at 800 ppm. Leaves fed with 800 ppm [CO2] showed one-third reduced stomatal conductance (gs) and transpiration (E), and their gs was in turn slightly lower than in 200 ppm– and in 0 ppm–treated leaves. The 800 ppm air [CO2] strongly impaired both NtAQP1 and NtPIP2;1 gene expression, whereas 0 ppm air [CO2], a concentration below any in vivo possible conditions and specifically chosen to maximize the gene expression alteration, increased only the NtAQP1 transcript level. We propose that NtAQP1 expression, an aquaporin devoted to CO2 transport, positively responds to CO2 scarcity in the air in the whole range 0–800 ppm. On the contrary, expression of NtPIP2;1, an aquaporin not devoted to CO2 transport, is related to water balance in the leaf, and changes in parallel with gs. These observations fit in a model where upregulation of leaf aquaporins is activated at low Ci, while downregulation occurs when high Ci saturates photosynthesis and causes stomatal closure. PMID:27089333

  6. Solving widespread low-concentration VOC air pollution problems: Gas-phase photocatalytic oxidation answers the needs of many small businesses

    SciTech Connect

    Lyons, C; Turchi, C; Gratson, D

    1995-04-01

    Many small businesses are facing new regulations under the 1990 Amendments to the Clean Air Act. Regulators, as well as the businesses themselves, face new challenges to control small point-source air pollution emissions. An individual business-such as a dry cleaner, auto repair shop, bakery, coffee roaster, photo print shop, or chemical company-may be an insignificant source of air pollution, but collectively, the industry becomes a noticeable source. Often the businesses are not equipped to respond to new regulatory requirements because of limited resources, experience, and expertise. Also, existing control strategies may be inappropriate for these businesses, having been developed for major industries with high volumes, high pollutant concentrations, and substantial corporate resources. Gas-phase photocatalytic oxidation (PCO) is an option for eliminating low-concentration, low-flow-rate emissions of volatile organic compounds (VOCs) from small business point sources. The advantages PCO has over other treatment techniques are presented in this paper. This paper also describes how PCO can be applied to specific air pollution problems. We present our methodology for identifying pollution problems for which PCO is applicable and for reaching the technology`s potential end users. PCO is compared to other gas-phase VOC control technologies.

  7. Who should take responsibility for decisions on internationally recommended datasets? The case of the mass concentration of mercury in air at saturation

    NASA Astrophysics Data System (ADS)

    Brown, Richard J. C.; Brewer, Paul J.; Ent, Hugo; Fisicaro, Paola; Horvat, Milena; Kim, Ki-Hyun; Quétel, Christophe R.

    2015-10-01

    This paper considers how decisions on internationally recommended datasets are made and implemented and, further, how the ownership of these decisions comes about. Examples are given of conventionally agreed data and values where the responsibility is clear and comes about through official designation or by common usage and practice over long time periods. The example of the dataset describing the mass concentration of mercury in air at saturation is discussed in detail. This is a case where there are now several competing datasets that are in disagreement with each other, some with historical authority and some more recent but, arguably, with more robust metrological traceability to the SI. Further, it is elaborated that there is no body charged with the responsibility to make a decision on an international recommendation for such a dataset. This has led to the situation where several competing datasets are in use simultaneously. Close parallels are drawn with the current debate over changes to the ozone absorption cross section, which has equal importance to the measurement of ozone amount fraction in air and to subsequent compliance with air quality legislation. It is noted that in the case of the ozone cross section there is already a committee appointed to deliberate over any change. We make the proposal that a similar committee, under the auspices of IUPAC or the CIPM’s CCQM (if it adopted a reference data function) could be formed to perform a similar role for the mass concentration of mercury in air at saturation.

  8. Sensitivity of Urban Airshed Model (UAM-IV) calculated air pollutant concentrations to the vertical diffusion parameterization during convective meteorological situations

    SciTech Connect

    Nowacki, P.; Samson, P.J.; Sillman, S.

    1996-10-01

    It is shown that Urban Airshed Model (UAM-IV) calculated air pollutant concentrations during photochemical smog episodes in Atlanta, Georgia, depend strongly on the numerical parameterization of the daytime vertical diffusivity. Results found suggest that vertical mixing is overestimated by the UAM-IV during unstable daytime conditions, as calculated vertical diffusivity values exceed measured and comparable literature values. Although deviations between measured and UAM-IV calculated air pollutant concentrations may only in part be due the UAM-IV diffusivity parameterization, results indicate the large error potential in vertical diffusivity parameterization. Easily implemented enhancements to UAM-IV algorithms are proposed, thus improving UAM-IV modeling performance during unstable stratification. 38 refs., 14 figs., 1 tab.

  9. Concentrations and potential health risks of methyl tertiary-butyl ether (MTBE) in air and drinking water from Nanning, South China.

    PubMed

    Zhang, Li'e; Qin, Jian; Zhang, Zhiyong; Li, Qin; Huang, Jiongli; Peng, Xiaowu; Qing, Li; Liang, Guiqiang; Liang, Linhan; Huang, Yuman; Yang, Xiaobo; Zou, Yunfeng

    2016-01-15

    Levels of methyl tertiary-butyl ether (MTBE) in occupational air, ambient air, and drinking water in Nanning, South China, were investigated, and then their potential health risks to occupational workers and the general public were evaluated. Results show that the MTBE concentration in occupational air from 13 service stations was significantly higher than that in ambient air from residential areas (p<0.0001); both are far lower than the threshold limit value-time weighted average of MTBE regulated in the United States (US). The drinking water samples from household taps yielded detectable MTBE in the range of 0.04-0.33 μg/L, which is below the US drinking water standard of 20-40 μg/L. The non-carcinogenic risk of MTBE from air inhalation may be negligible because the calculated hazard quotient was less than 1. The mean MTBE lifetime cancer risk was within the acceptable limit of 1 × 10(-6) to 1 × 10(-4), but the lifetime cancer risk of refueling workers in the urban service station at the 95th percentile slightly exceeded the maximum acceptable carcinogen risk (1 × 10(-4)), indicating the potential carcinogenic health effects on the population highly exposed to MTBE in this region. The hazard index and carcinogenic risk of MTBE in drinking water were significantly lower than the safe limit of US Environmental Protection Agency, suggesting that drinking water unlikely poses significant health risks to the residents in Nanning.

  10. Predicting regional emissions and near-field air concentrations of soil fumigants using modest numerical algorithms: a case study using 1,3-dichloropropene.

    PubMed

    Cryer, S A; van Wesenbeeck, I J; Knuteson, J A

    2003-05-21

    Soil fumigants, used to control nematodes and crop disease, can volatilize from the soil application zone and into the atmosphere to create the potential for human inhalation exposure. An objective for this work is to illustrate the ability of simple numerical models to correctly predict pesticide volatilization rates from agricultural fields and to expand emission predictions to nearby air concentrations for use in the exposure component of a risk assessment. This work focuses on a numerical system using two U.S. EPA models (PRZM3 and ISCST3) to predict regional volatilization and nearby air concentrations for the soil fumigant 1,3-dichloropropene. New approaches deal with links to regional databases, seamless coupling of emission and dispersion models, incorporation of Monte Carlo sampling techniques to account for parametric uncertainty, and model input sensitivity analysis. Predicted volatility flux profiles of 1,3-dichloropropene (1,3-D) from soil for tarped and untarped fields were compared against field data and used as source terms for ISCST3. PRZM3 can successfully estimate correct order of magnitude regional soil volatilization losses of 1,3-D when representative regional input parameters are used (soil, weather, chemical, and management practices). Estimated 1,3-D emission losses and resulting air concentrations were investigated for five geographically diverse regions. Air concentrations (15-day averages) are compared with the current U.S. EPA's criteria for human exposure and risk assessment to determine appropriate setback distances from treated fields. Sensitive input parameters for volatility losses were functions of the region being simulated.

  11. Assessment of concentrations of trace elements in ground water and soil at the Small-Arms Firing Range, Shaw Air Force Base, South Carolina

    USGS Publications Warehouse

    Landmeyer, J.E.

    1994-01-01

    Ground-water samples were collected from four shallow water-table aquifer observation wells beneath the Small-Arms Firing Range study area at Shaw Air Force Base. Water-chemistry analyses indicated that total lead concentrations in shallow ground water beneath the study area do not exceed the U.S. Environmental Protection Agency maximum conta