Science.gov

Sample records for aerosol wet deposition

  1. Controls on aerosol wet deposition from satellite-based (re-)analysis products

    NASA Astrophysics Data System (ADS)

    Chuang, P. Y.

    2015-12-01

    Aerosol wet deposition is the key aerosol loss mechanism globally, yet is not well-understood relative to aerosol sources and transformations. The difficulty in generating appropriate observational data sets is one important barrier to the study of aerosol wet removal. In this study, we combine two independent products based on satellite measurements. Aerosol optical depth (AOD) is obtained from the ECMWF Monitoring Atmospheric Composition and Climate (MACC) project, which is a re-analysis product that assimilates MODIS-retrieved aerosol optical depth. Rainfall is obtained from the Tropical Rainfall Measurement Mission (TRMM) Multi-satellite Precipitation Analysis version 7 (TMPA-7). The latter product is available only from 50°N to 50°S, which sets our region of study. The data used is from 2011-12, is averaged to 6-hr intervals and has a horizontal resolution of 0.25°x0.25°. Our approach involves constructing a Lagrangian advection scheme that predicts aerosol AOD at the next time step (i.e. 6 hr in the future) based on current time step AOD and winds, and neglecting all aerosol sources and sinks. Predicted AOD is then compared with MACC reanalysis AOD conditioned on Lagrangian parcels that experienced rainfall during that interval, with AOD decreases attributed to wet deposition. Aerosol wet deposition is often parameterized in models as a function of rainfall rate using a power law. We evaluate the validity of such a power law relationship, and, when valid, compute the power law exponent globally, and by region (including continental and maritime locations) to reveal seasonal and geographic variability. Assuming precipitation is modulated by aerosol, at least in some regimes, then it follows that wet deposition also depends on AOD, and we quantify the strength of this coupling. This same approach could be used to study wet deposition of trace gases such as CO and ozone, as these are also available from the MACC re-analysis.

  2. Assessment of dry and wet atmospheric deposits of radioactive aerosols: application to Fukushima radiocaesium fallout.

    PubMed

    Gonze, Marc-André; Renaud, Philippe; Korsakissok, Irène; Kato, Hiroaki; Hinton, Thomas G; Mourlon, Christophe; Simon-Cornu, Marie

    2014-10-07

    The Fukushima Dai-ichi nuclear accident led to massive atmospheric deposition of radioactive substances onto the land surfaces. The spatial distribution of deposits has been estimated by Japanese authorities for gamma-emitting radionuclides through either airborne monitoring surveys (since April 2011) or in situ gamma-ray spectrometry of bare soil areas (since summer 2011). We demonstrate that significant differences exist between the two surveys for radiocaesium isotopes and that these differences can be related to dry deposits through the use of physically based relationships involving aerosol deposition velocities. The methodology, which has been applied to cesium-134 and cesium-137 deposits within 80-km of the nuclear site, provides reasonable spatial estimations of dry and wet deposits that are discussed and compared to atmospheric numerical simulations from the Japanese Atomic Energy Agency and the French Institute of Radioprotection and Nuclear Safety. As a complementary approach to numerical simulations, this field-based analysis has the possibility to contribute information that can be applied to the understanding and assessment of dose impacts to human populations and the environment around Fukushima.

  3. Increasing aeolian dust deposition to snowpacks in the Rocky Mountains inferred from snowpack, wet deposition, and aerosol chemistry

    NASA Astrophysics Data System (ADS)

    Clow, David W.; Williams, Mark W.; Schuster, Paul F.

    2016-12-01

    Mountain snowpacks are a vital natural resource for ∼1.5 billion people in the northern Hemisphere, helping to meet human and ecological demand for water in excess of that provided by summer rain. Springtime warming and aeolian dust deposition accelerate snowmelt, increasing the risk of water shortages during late summer, when demand is greatest. While climate networks provide data that can be used to evaluate the effect of warming on snowpack resources, there are no established regional networks for monitoring aeolian dust deposition to snow. In this study, we test the hypothesis that chemistry of snow, wet deposition, and aerosols can be used as a surrogate for dust deposition to snow. We then analyze spatial patterns and temporal trends in inferred springtime dust deposition to snow across the Rocky Mountains, USA, for 1993-2014. Geochemical evidence, including strong correlations (r2 ≥ 0.94) between Ca2+, alkalinity, and dust concentrations in snow deposited during dust events, indicate that carbonate minerals in dust impart a strong chemical signature that can be used to track dust deposition to snow. Spatial patterns in chemistry of snow, wet deposition, and aerosols indicate that dust deposition increases from north to south in the Rocky Mountains, and temporal trends indicate that winter/spring dust deposition increased by 81% in the southern Rockies during 1993-2014. Using a multivariate modeling approach, we determined that increases in dust deposition and decreases in springtime snowfall combined to accelerate snowmelt timing in the southern Rockies by approximately 7-18 days between 1993 and 2014. Previous studies have shown that aeolian dust emissions may have doubled globally during the 20th century, possibly due to drought and land-use change. Climate projections for increased aridity in the southwestern U.S., northern Africa, and other mid-latitude regions of the northern Hemisphere suggest that aeolian dust emissions may continue to increase

  4. Increasing aeolian dust deposition to snowpacks in the Rocky Mountains inferred from snowpack, wet deposition, and aerosol chemistry

    USGS Publications Warehouse

    Clow, David W.; Williams, Mark W.; Schuster, Paul F.

    2016-01-01

    Mountain snowpacks are a vital natural resource for ∼1.5 billion people in the northern Hemisphere, helping to meet human and ecological demand for water in excess of that provided by summer rain. Springtime warming and aeolian dust deposition accelerate snowmelt, increasing the risk of water shortages during late summer, when demand is greatest. While climate networks provide data that can be used to evaluate the effect of warming on snowpack resources, there are no established regional networks for monitoring aeolian dust deposition to snow. In this study, we test the hypothesis that chemistry of snow, wet deposition, and aerosols can be used as a surrogate for dust deposition to snow. We then analyze spatial patterns and temporal trends in inferred springtime dust deposition to snow across the Rocky Mountains, USA, for 1993–2014. Geochemical evidence, including strong correlations (r2 ≥ 0.94) between Ca2+, alkalinity, and dust concentrations in snow deposited during dust events, indicate that carbonate minerals in dust impart a strong chemical signature that can be used to track dust deposition to snow. Spatial patterns in chemistry of snow, wet deposition, and aerosols indicate that dust deposition increases from north to south in the Rocky Mountains, and temporal trends indicate that winter/spring dust deposition increased by 81% in the southern Rockies during 1993–2014. Using a multivariate modeling approach, we determined that increases in dust deposition and decreases in springtime snowfall combined to accelerate snowmelt timing in the southern Rockies by approximately 7–18 days between 1993 and 2014. Previous studies have shown that aeolian dust emissions may have doubled globally during the 20th century, possibly due to drought and land-use change. Climate projections for increased aridity in the southwestern U.S., northern Africa, and other mid-latitude regions of the northern Hemisphere suggest that aeolian dust emissions may continue to

  5. The effect of dry and wet deposition of condensable vapors on secondary organic aerosols concentrations over the continental US

    NASA Astrophysics Data System (ADS)

    Knote, C.; Hodzic, A.; Jimenez, J. L.

    2015-01-01

    The effect of dry and wet deposition of semi-volatile organic compounds (SVOCs) in the gas phase on the concentrations of secondary organic aerosol (SOA) is reassessed using recently derived water solubility information. The water solubility of SVOCs was implemented as a function of their volatility distribution within the WRF-Chem regional chemistry transport model, and simulations were carried out over the continental United States for the year 2010. Results show that including dry and wet removal of gas-phase SVOCs reduces annual average surface concentrations of anthropogenic and biogenic SOA by 48 and 63% respectively over the continental US. Dry deposition of gas-phase SVOCs is found to be more effective than wet deposition in reducing SOA concentrations (-40 vs. -8% for anthropogenics, and -52 vs. -11% for biogenics). Reductions for biogenic SOA are found to be higher due to the higher water solubility of biogenic SVOCs. The majority of the total mass of SVOC + SOA is actually deposited via the gas phase (61% for anthropogenics and 76% for biogenics). Results are sensitive to assumptions made in the dry deposition scheme, but gas-phase deposition of SVOCs remains crucial even under conservative estimates. Considering reactivity of gas-phase SVOCs in the dry deposition scheme was found to be negligible. Further sensitivity studies where we reduce the volatility of organic matter show that consideration of gas-phase SVOC removal still reduces average SOA concentrations by 31% on average. We consider this a lower bound for the effect of gas-phase SVOC removal on SOA concentrations. A saturation effect is observed for Henry's law constants above 108 M atm-1, suggesting an upper bound of reductions in surface level SOA concentrations by 60% through removal of gas-phase SVOCs. Other models that do not consider dry and wet removal of gas-phase SVOCs would hence overestimate SOA concentrations by roughly 50%. Assumptions about the water solubility of SVOCs made in

  6. The effect of dry and wet deposition of condensable vapors on secondary organic aerosols concentrations over the continental US

    DOE PAGES

    Knote, C.; Hodzic, A.; Jimenez, J. L.

    2015-01-06

    The effect of dry and wet deposition of semi-volatile organic compounds (SVOCs) in the gas phase on the concentrations of secondary organic aerosol (SOA) is reassessed using recently derived water solubility information. The water solubility of SVOCs was implemented as a function of their volatility distribution within the WRF-Chem regional chemistry transport model, and simulations were carried out over the continental United States for the year 2010. Results show that including dry and wet removal of gas-phase SVOCs reduces annual average surface concentrations of anthropogenic and biogenic SOA by 48 and 63% respectively over the continental US. Dry deposition ofmore » gas-phase SVOCs is found to be more effective than wet deposition in reducing SOA concentrations (−40 vs. −8% for anthropogenics, and −52 vs. −11% for biogenics). Reductions for biogenic SOA are found to be higher due to the higher water solubility of biogenic SVOCs. The majority of the total mass of SVOC + SOA is actually deposited via the gas phase (61% for anthropogenics and 76% for biogenics). Results are sensitive to assumptions made in the dry deposition scheme, but gas-phase deposition of SVOCs remains crucial even under conservative estimates. Considering reactivity of gas-phase SVOCs in the dry deposition scheme was found to be negligible. Further sensitivity studies where we reduce the volatility of organic matter show that consideration of gas-phase SVOC removal still reduces average SOA concentrations by 31% on average. We consider this a lower bound for the effect of gas-phase SVOC removal on SOA concentrations. A saturation effect is observed for Henry's law constants above 108 M atm−1, suggesting an upper bound of reductions in surface level SOA concentrations by 60% through removal of gas-phase SVOCs. Other models that do not consider dry and wet removal of gas-phase SVOCs would hence overestimate SOA concentrations by roughly 50%. Assumptions about the water solubility

  7. Estimation of sulfate trends at selected national park service sites: Does the wet deposition record parallel the aerosol record?

    SciTech Connect

    Shealy, R.T.; Bowersox, V.C.

    1997-12-31

    Recently temporal trends in sulfate concentration in fine-particle aerosols have been measured at a set of twelve National Park Service (NPS) sites using the Interagency Monitoring of Visual Environments (IMPROVE) network. Trends were computed for each climatological season over the period 1982-1993. The distribution of trend direction was nearly symmetric; of the 48 possible site-season combinations, 11 were negative, 8 positive, and the remainder exhibited no trend. These are surprising findings in the context of nearly constant SO{sub 2} emissions in the East over this period (EPA, 1991) and generally-decreasing trends over the entire US computed from wet deposition sulfate concentrations collected by the National Atmospheric Deposition Program/National Trends Network (NADP/NTN). Of particular interest are the three largest positive trends: Grand Canyon exhibited a 4.2% increase in winter, Great Smoky Mountains had an increase of 3.9% in summer, and Shenandoah had an increase of 3.7% in summer, Recently, the latter two sites have been studied over a period more recent than the original study (1982-1995) and the trends are smaller, but they remain positive. It has been suggested that these findings are a statistical artifact: that in a large set of trend tests over many sites and seasons, a few will by chance be found to have statistically significant positive trends, even under the condition of no trends.A special study was undertaken using the subset of the NPS sites with co-located IMPROVE and NADP/NTN samplers. Direct comparison of aerosol sulfur and wet deposition sulfate trends is done to determine their relationship to each other. The NPS sites that qualify as candidates in the study are: Shenandoah, Great Smoky Mountains, Glacier, Yosemite, Grand Canyon, Mesa Verde, and Big Bend Parks.

  8. The effect of dry and wet deposition of condensable vapors on secondary organic aerosols concentrations over the continental US

    NASA Astrophysics Data System (ADS)

    Knote, C.; Hodzic, A.; Jimenez, J. L.

    2014-05-01

    The effect of dry and wet deposition of semi-volatile organic compounds (SVOC) in the gas-phase on the concentrations of secondary organic aerosol (SOA) is reassessed using recently derived water solubility information. The water solubility of SVOCs was implemented as a function of their volatility distribution within the regional chemistry transport model WRF-Chem, and simulations were carried out over the continental United States for the year 2010. Results show that including dry and wet removal of gas-phase SVOCs reduces annual average surface concentrations of anthropogenic and biogenic SOA by 48% and 63% respectively over the continental US Dry deposition of gas-phase SVOCs is found to be more effective than wet deposition in reducing SOA concentrations (-40% vs. -8% for anthropogenics, -52% vs. -11% for biogenics). Reductions for biogenic SOA are found to be higher due to the higher water solubility of biogenic SVOCs. The majority of the total mass of SVOC + SOA is actually deposited via the gas-phase (61% for anthropogenics, 76% for biogenics). A number of sensitivity studies shows that this is a robust feature of the modeling system. Other models that do not consider dry and wet removal of gas-phase SVOCs would hence overestimate SOA concentrations by roughly 50%. Assumptions about the water solubility of SVOCs made in some current modeling systems (H* = 105 M atm-1; H* = H* (HNO3)) still lead to an overestimation of 25% / 10% compared to our best estimate. A saturation effect is observed for Henry's law constants above 108 M atm-1, suggesting an upper bound of reductions in surface level SOA concentrations by 60% through removal of gas-phase SVOCs. Considering reactivity of gas-phase SVOCs in the dry deposition scheme was found to be negligible. Further sensitivity studies where we reduce the volatility of organic matter show that consideration of gas-phase SVOC removal still reduces average SOA concentrations by 31% on average. We consider this a lower

  9. 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.

  10. Modeled size-segregated wet and dry deposition budgets of soil dust aerosol during ACE-Asia 2001: Implications for trans-Pacific transport

    NASA Astrophysics Data System (ADS)

    Zhao, T. L.; Gong, S. L.; Zhang, X. Y.; McKendry, I. G.

    2003-12-01

    Size-segregated budgets of soil dust aerosols in Asia for spring 2001 during ACE-Asia were investigated using the NARCM model [, 2003b]. Simulated mass size distributions of dust deposition showed a similar size distribution to the dust emission fluxes over the source regions and a decreased peak corresponding to a 1-3 μm diameter range over downwind regions. The simulations suggest that dry deposition was a dominant dust removal process near the source areas and the removal of dust particles by precipitation was the major process over the trans-Pacific transport pathway, where wet deposition exceeded dry deposition by up to a factor of 10. The Asian dust deposition from the atmosphere to the North Pacific Ocean was correlated not only with precipitation over the North Pacific but also with the dust transport patterns. Variations of monthly Asian dust outflow were identified with the latitudinal center of transport at 38°N in March, 42°N in April, and 47°N in May. The monthly trans-Pacific transport patterns of Asian dust in spring were characterized. The transport axis extended around 30°N and 40°N from the east Asian subcontinent to the North Pacific in March. A zonal transport pathway around 40°N was well developed in April over the North Pacific and reached North America. However, the transport in May was separated into two pathways: an eastward zonal path over the North Pacific and a meridional path from the source regions to the northeast Asian continent. On the basis of the averaged dust budgets during spring 2001, it was found that the major sources of Asian dust were located in the desert regions in China and Mongolia with an estimated dust emission of 21.5 tons km-2, and the regions from the Loess Plateau to the North Pacific were sinks of soil dust aerosols with the Loess Plateau as the main sink for Asian dust.

  11. Thunderstorms Increase Mercury Wet Deposition.

    PubMed

    Holmes, Christopher D; Krishnamurthy, Nishanth P; Caffrey, Jane M; Landing, William M; Edgerton, Eric S; Knapp, Kenneth R; Nair, Udaysankar S

    2016-09-06

    Mercury (Hg) wet deposition, transfer from the atmosphere to Earth's surface by precipitation, in the United States is highest in locations and seasons with frequent deep convective thunderstorms, but it has never been demonstrated whether the connection is causal or simple coincidence. We use rainwater samples from over 800 individual precipitation events to show that thunderstorms increase Hg concentrations by 50% relative to weak convective or stratiform events of equal precipitation depth. Radar and satellite observations reveal that strong convection reaching the upper troposphere (where high atmospheric concentrations of soluble, oxidized mercury species (Hg(II)) are known to reside) produces the highest Hg concentrations in rain. As a result, precipitation meteorology, especially thunderstorm frequency and total rainfall, explains differences in Hg deposition between study sites located in the eastern United States. Assessing the fate of atmospheric mercury thus requires bridging the scales of global transport and convective precipitation.

  12. Uncertainty associated with convective wet removal of entrained aerosols in a global climate model

    NASA Astrophysics Data System (ADS)

    Croft, B.; Pierce, J. R.; Martin, R. V.; Hoose, C.; Lohmann, U.

    2012-11-01

    The uncertainties associated with the wet removal of aerosols entrained above convective cloud bases are investigated in a global aerosol-climate model (ECHAM5-HAM) under a set of limiting assumptions for the wet removal of the entrained aerosols. The limiting assumptions for the wet removal of entrained aerosols are negligible scavenging and vigorous scavenging (either through activation, with size-dependent impaction scavenging, or with the prescribed fractions of the standard model). To facilitate this process-based study, an explicit representation of cloud-droplet-borne and ice-crystal-borne aerosol mass and number, for the purpose of wet removal, is introduced into the ECHAM5-HAM model. This replaces and is compared with the prescribed cloud-droplet-borne and ice-crystal-borne aerosol fraction scavenging scheme of the standard model. A 20% to 35% uncertainty in simulated global, annual mean aerosol mass burdens and optical depth (AOD) is attributed to different assumptions for the wet removal of aerosols entrained above convective cloud bases. Assumptions about the removal of aerosols entrained above convective cloud bases control modeled upper tropospheric aerosol concentrations by as much as one order of magnitude. Simulated aerosols entrained above convective cloud bases contribute 20% to 50% of modeled global, annual mean aerosol mass convective wet deposition (about 5% to 10% of the total dry and wet deposition), depending on the aerosol species, when including wet scavenging of those entrained aerosols (either by activation, size-dependent impaction, or with the prescribed fraction scheme). Among the simulations, the prescribed fraction and size-dependent impaction schemes yield the largest global, annual mean aerosol mass convective wet deposition (by about two-fold). However, the prescribed fraction scheme has more vigorous convective mixed-phase wet removal (by two to five-fold relative to the size-dependent impaction scheme) since nearly all

  13. Photochemical organonitrate formation in wet aerosols

    NASA Astrophysics Data System (ADS)

    Lim, Yong Bin; Kim, Hwajin; Kim, Jin Young; Turpin, Barbara J.

    2016-10-01

    Water is the most abundant component of atmospheric fine aerosol. However, despite rapid progress, multiphase chemistry involving wet aerosols is still poorly understood. In this work, we report results from smog chamber photooxidation of glyoxal- and OH-containing ammonium sulfate or sulfuric acid particles in the presence of NOx and O3 at high and low relative humidity. Particles were analyzed using ultra-performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS). During the 3 h irradiation, OH oxidation products of glyoxal that are also produced in dilute aqueous solutions (e.g., oxalic acids and tartaric acids) were formed in both ammonium sulfate (AS) aerosols and sulfuric acid (SA) aerosols. However, the major products were organonitrogens (CHNO), organosulfates (CHOS), and organonitrogen sulfates (CHNOS). These were also the dominant products formed in the dark chamber, indicating non-radical formation. In the humid chamber (> 70 % relative humidity, RH), two main products for both AS and SA aerosols were organonitrates, which appeared at m / z- 147 and 226. They were formed in the aqueous phase via non-radical reactions of glyoxal and nitric acid, and their formation was enhanced by photochemistry because of the photochemical formation of nitric acid via reactions of peroxy radicals, NOx and OH during the irradiation.

  14. A 20-year simulated climatology of global dust aerosol deposition.

    PubMed

    Zheng, Yu; Zhao, Tianliang; Che, Huizheng; Liu, Yu; Han, Yongxiang; Liu, Chong; Xiong, Jie; Liu, Jianhui; Zhou, Yike

    2016-07-01

    Based on a 20-year (1991-2010) simulation of dust aerosol deposition with the global climate model CAM5.1 (Community Atmosphere Model, version 5.1), the spatial and temporal variations of dust aerosol deposition were analyzed using climate statistical methods. The results indicated that the annual amount of global dust aerosol deposition was approximately 1161±31Mt, with a decreasing trend, and its interannual variation range of 2.70% over 1991-2010. The 20-year average ratio of global dust dry to wet depositions was 1.12, with interannual variation of 2.24%, showing the quantity of dry deposition of dust aerosol was greater than dust wet deposition. High dry deposition was centered over continental deserts and surrounding regions, while wet deposition was a dominant deposition process over the North Atlantic, North Pacific and northern Indian Ocean. Furthermore, both dry and wet deposition presented a zonal distribution. To examine the regional changes of dust aerosol deposition on land and sea areas, we chose the North Atlantic, Eurasia, northern Indian Ocean, North Pacific and Australia to analyze the interannual and seasonal variations of dust deposition and dry-to-wet deposition ratio. The deposition amounts of each region showed interannual fluctuations with the largest variation range at around 26.96% in the northern Indian Ocean area, followed by the North Pacific (16.47%), Australia (9.76%), North Atlantic (9.43%) and Eurasia (6.03%). The northern Indian Ocean also had the greatest amplitude of interannual variation in dry-to-wet deposition ratio, at 22.41%, followed by the North Atlantic (9.69%), Australia (6.82%), North Pacific (6.31%) and Eurasia (4.36%). Dust aerosol presented a seasonal cycle, with typically strong deposition in spring and summer and weak deposition in autumn and winter. The dust deposition over the northern Indian Ocean exhibited the greatest seasonal change range at about 118.00%, while the North Atlantic showed the lowest seasonal

  15. Removal of atmospheric ethanol by wet deposition

    NASA Astrophysics Data System (ADS)

    Felix, J. David; Willey, Joan D.; Thomas, Rachel K.; Mullaugh, Katherine M.; Avery, G. Brooks; Kieber, Robert J.; Mead, Ralph N.; Helms, John; Giubbina, Fernanda F.; Campos, M. Lucia A. M.; Cala, John

    2017-02-01

    The global wet deposition flux of ethanol is estimated to be 2.4 ± 1.6 Tg/yr with a conservative range of 0.2-4.6 Tg/yr based upon analyses of 219 wet deposition samples collected at 12 locations globally. This estimate calculated by using observed wet deposition ethanol concentrations is in agreement with previous models (1.4-5 Tg/yr) predicting the wet deposition sink using Henry's law coefficients and atmospheric ethanol concentrations. Wet deposition is estimated to remove between 6 and 17% of the total ethanol emitted to the atmosphere on an annual basis. The concentration of ethanol in marine rain (25 ± 6 nM) is an order of magnitude less than in the majority of terrestrial rains (345 ± 280 nM). Terrestrial rain samples collected in locations impacted by high local sources of biofuel usage and locations downwind from ethanol distilleries were an order of magnitude higher in ethanol concentration (3090 ± 448 nM) compared to rain collected in terrestrial locations not impacted by these sources. These results indicate that wet deposition of ethanol is heavily influenced by local sources. Results of this study are important because they suggest that as biofuel production and usage increase, the concentration of ethanol in the atmosphere will increase as well the wet deposition flux. Additional research constraining the sources, sinks, and atmospheric impacts of ethanol is necessary to better assist in the debate as whether or not to increase consumption of the alcohol as a biofuel.

  16. The Dry Aerosol Deposition Device (DADD): An Instrument for Depositing Microbial Aerosols onto Surfaces (PREPRINT)

    DTIC Science & Technology

    2008-12-01

    AFRL-RX-TY-TP-2008-4617 PREPRINT THE DRY AEROSOL DEPOSITION DEVICE (DADD): AN INSTRUMENT FOR DEPOSITING MICROBIAL AEROSOLS ONTO SURFACES... Deposition Device (DADD): 3  An Instrument for Depositing Microbial Aerosols onto Surfaces 4  5  Authors and affiliation 6  7  Heimbuch, B.K., Kinney...footprint, variable loading, etc.). We developed a Dry Aerosol 33  Deposition Device (DADD) that uses impaction rather than settling for loading surfaces

  17. The Dry Aerosol Deposition Device (DADD): An Instrument for Depositing Microbial Aerosols onto Surfaces

    DTIC Science & Technology

    2008-12-01

    AFRL-RX-TY-TR-2008-4592 THE DRY AEROSOL DEPOSITION DEVICE (DADD): AN INSTRUMENT FOR DEPOSITING MICROBIAL AEROSOLS ONTO SURFACES...RESPONSIBLE PERSON 19b. TELEPHONE NUMBER (Include area code) 30-NOV-2008 Final Technical Report 01-OCT-2004 -- 02-OCT-2008 The Dry Aerosol Deposition ...Device (DADD): An Instrument for Depositing Microbial Aerosols Onto Surfaces FA4819-07-D-0001 99999F DODT 00 DODT0056 Heimbuch, Brian K.; Kinney

  18. Endosulfan wet deposition in Southern Florida (USA).

    PubMed

    Potter, Thomas L; Hapeman, Cathleen J; McConnell, Laura L; Harman-Fetcho, Jennifer A; Schmidt, Walter F; Rice, Clifford P; Schaffer, Bruce

    2014-01-15

    The atmosphere is an important transport route for semi-volatile pesticides like endosulfan. Deposition, which depends on physical-chemical properties, use patterns, and climatic conditions, can occur at local, regional, and global scales. Adverse human and ecological impact may result. We measured endosulfan wet deposition in precipitation over a 4-year period within an area of high agricultural use in Southern Florida (USA) and in nearby Biscayne and Everglades National Parks. Endosulfan's two isomers and degradate, endosulfan sulfate, were detected at high frequency with the order of detection and concentration being β-endosulfan>α-endosulfan>endosulfan sulfate. Within the agricultural area, detection frequency (55 to 98%) mean concentrations (5 to 87 ng L(-1)) and total daily deposition (200 ng m(-2) day(-1)) exceeded values at other sites by 5 to 30-fold. Strong seasonal trends were also observed with values at all monitored sites significantly higher during peak endosulfan use periods when vegetable crops were produced. Relatively high deposition in the crop production area and observations that concentrations exceeded aquatic life toxicity thresholds at all sites indicated that endosulfan volatilization and wet deposition are of ecotoxicological concern to the region. This study emphasizes the need to include localized volatilization and deposition of endosulfan and other semi-volatile pesticides in risk assessments in Southern Florida and other areas with similar climatic and crop production profiles.

  19. Wet deposition in the northeastern United States

    SciTech Connect

    Wilson, J; Mohnen, V; Kadlecek, J

    1980-12-01

    Attempts are made to examine concentration and wet deposition of pollutant material at selected stations within the northeastern United States and to characterize as many events as possible with respect to air mass origin. Further attempts are made to develop a regional pattern for the deposition of dominant ion species. MAP3S (US Multistate Atmospheric Power Production Pollution Study) data for 1977 to 1979 are used to determine concentration and deposition on an event basis from which monthly, seasonal, annual, and cumulative averages are developed. The ARL-ATAD trajectory model is used to characterize individual events as to air mass origin. Case studies are examined to illustrate variability in the chemical composition of precipitation originating from distinctly different air mass trajectories. A difference in concentration of pollution-related ions in precipitation is noted between Midwest/Ohio Valley and Great Lakes/Canadian air mass origins for carefully selected cases. Total deposition of the major ions is examined in an effort to develop a regional pattern for deposition over a period of at least one year. For that purpose, total deposition is normalized to remove the variability in precipitation amounts for inter-station comparison. No marked gradient is noted in the normalized deposition totals within the northeast of the United States. The Adirondack region exhibited the lowest normalized ion deposition value, while the Illinois station showed the highest of the MAP3S network. The data analysis suggest that the acid rain phenomena covers the entire northeast. The concept of large scale mixing emerges to account for the lack of a significant gradient in the normalized deposition.

  20. Aerosol Deposition and Solar Panel Performance

    NASA Astrophysics Data System (ADS)

    Arnott, W. P.; Rollings, A.; Taylor, S. J.; Parks, J.; Barnard, J.; Holmes, H.

    2015-12-01

    Passive and active solar collector farms are often located in relatively dry desert regions where cloudiness impacts are minimized. These farms may be susceptible to reduced performance due to routine or episodic aerosol deposition on collector surfaces. Intense episodes of wind blown dust deposition may negatively impact farm performance, and trigger need to clean collector surfaces. Aerosol deposition rate depends on size, morphology, and local meteorological conditions. We have developed a system for solar panel performance testing under real world conditions. Two identical 0.74 square meter solar panels are deployed, with one kept clean while the other receives various doses of aerosol deposition or other treatments. A variable load is used with automation to record solar panel maximum output power every 10 minutes. A collocated sonic anemometer measures wind at 10 Hz, allowing for both steady and turbulent characterization to establish a link between wind patterns and particle distribution on the cells. Multispectral photoacoustic instruments measure aerosol light scattering and absorption. An MFRSR quantifies incoming solar radiation. Solar panel albedo is measured along with the transmission spectra of particles collected on the panel surface. Key questions are: At what concentration does aerosol deposition become a problem for solar panel performance? What are the meteorological conditions that most strongly favor aerosol deposition, and are these predictable from current models? Is it feasible to use the outflow from an unmanned aerial vehicle hovering over solar panels to adequately clean their surface? Does aerosol deposition from episodes of nearby forest fires impact performance? The outlook of this research is to build a model that describes environmental effects on solar panel performance. Measurements from summer and fall 2015 will be presented along with insights gleaned from them.

  1. Pulmonary Deposition of Aerosols in Microgravity

    NASA Technical Reports Server (NTRS)

    Prisk, G. Kim

    1997-01-01

    The intrapulmonary deposition of airborne particles (aerosol) in the size range of 0.5 to 5 microns is primarily due to gravitational sedimentation. In the microgravity (muG) environment, sedimentation is no longer active, and thus there should be marked changes in the amount and site of the deposition of these aerosol. We propose to study the total intrapulmonary deposition of aerosol spanning the range 0.5 to 5 microns in the KC-135 at both muG and at 1.8-G. This will be followed by using boli of 1.0 micron aerosol, inhaled at different points in a breath to study aerosol dispersion and deposition as a function of inspired depth. The results of these studies will have application in better understanding of pulmonary diseases related to inhaled particles (pneumoconioses), in studying drugs delivered by inhalation, and in understanding the consequence of long-term exposure to respirable aerosols in long-duration space flight.

  2. Lung deposition of droplet aerosols in monkeys.

    PubMed

    Cheng, Y S; Irshad, H; Kuehl, P; Holmes, T D; Sherwood, R; Hobbs, C H

    2008-09-01

    Nonhuman primates are often the animal models of choice to study the infectivity and therapy of inhaled infectious agents. Most animal models for inhaled infectious diseases use aerosol/droplets generated by an atomization technique such as a Collison nebulizer that produces particles in the size range of 1 to 3 microm in diameter. There are few data in the literature on deposition patterns in monkeys. Our study was designed to measure the deposition pattern in monkeys using droplets having diameters of 2 and 5 microm using an exposure system designed to expose monkeys to aerosols of infectious agents. Six cynomolgus monkeys were exposed to droplets. The aerosol solution was generated from a Vero cell supernate containing DMEM + 10% fetal bovine serum tagged with Tc-99m radiolabel. Collison and Retec nebulizers were used to generate small and large droplets, respectively. The particle size (as determined from a cascade impactor) showed an activity median aerodynamic diameter (AMAD) of 2.3 and 5.1 microm for the Collison and Retec nebulizer, respectively. The animals were anesthetized, placed in a plethysmography box, and exposed to the aerosol. The deposition pattern was determined using a gamma camera. Deposition in the head airways was 39% and 58% for 2.3- and 5.1-microm particle aerosols, respectively, whereas the deposition in the deep lung was 12% and 8%, respectively. This information will be useful in developing animal models for inhaled infectious agents.

  3. Aerosol Production from Charbroiled and Wet-Fried Meats

    NASA Astrophysics Data System (ADS)

    Niedziela, R. F.; Blanc, L. E.

    2012-12-01

    Previous work in our laboratory focused on the chemical and optical characterization of aerosols produced during the dry-frying of different meat samples. This method yielded a complex ensemble of particles composed of water and long-chain fatty acids with the latter dominated by oleic, stearic, and palmitic acids. The present study examines how wet-frying and charbroiling cooking methods affect the physical and chemical properties of their derived aerosols. Samples of ground beef, salmon, chicken, and pork were subject to both cooking methods in the laboratory, with their respective aerosols swept into a laminar flow cell where they were optically analyzed in the mid-infrared and collected through a gas chromatography probe for chemical characterization. This presentation will compare and contrast the nature of the aerosols generated in each cooking method, particularly those produced during charbroiling which exposes the samples, and their drippings, to significantly higher temperatures. Characterization of such cooking-related aerosols is important because of the potential impact of these particles on air quality, particularly in urban areas.

  4. Regional aerosol deposition in human upper airways

    SciTech Connect

    Swift, D.L.

    1990-11-01

    During the current reporting period experimental studies of aerosol deposition in replicate NOPL airways have carried out. A replicate model of a 4 week old infant nasal passage was constructed from MR scans. The model completes the age range from newborn'' to 4 years, there now being one child model for 4 different ages. Deposition studies have been performed with unattached radon progeny aerosols in collaboration with ITRI, Albuquerque, NM and NRPB, Chilton, UK. Overall measurements have been performed in adult and child nasal airways indicating that the child nasal passage was slightly more efficient than the adult in removing 1 nm particles at corresponding flow rates. A similar weak dependence on flow rate was observed. Local deposition studies in an adult nasal model indicated predominant deposition in the anterior region during inspiratory flow, but measurable deposition was found throughout the model. The deposition pattern during expiration was reverse, greater deposition being observed in the posterior region. Local deposition studies of attached progeny aerosol size (100--200 nm) were performed in adult and child nasal models using technigas'' and a gamma scintillation camera. Similar to the unattached size, deposition occurred throughout the models, but was greater in the anterior region.

  5. Mercury Wet Scavenging and Deposition Differences by Precipitation Type.

    PubMed

    Kaulfus, Aaron S; Nair, Udaysankar; Holmes, Christopher D; Landing, William M

    2017-03-07

    We analyze the effect of precipitation type on mercury wet deposition using a new database of individual rain events spanning the contiguous United States. Measurements from the Mercury Deposition Network (MDN) containing single rainfall events were identified and classified into six precipitation types. Mercury concentrations in surface precipitation follow a power law of precipitation depth that is modulated by precipitation system morphology. After controlling for precipitation depth, the highest mercury deposition occurs in supercell thunderstorms, with decreasing deposition in disorganized thunderstorms, quasi-linear convective systems (QLCS), extratropical cyclones, light rain, and land-falling tropical cyclones. Convective morphologies (supercells, disorganized, and QLCS) enhance wet deposition by a factor of at least 1.6 relative to nonconvective morphologies. Mercury wet deposition also varies by geographic region and season. After controlling for other factors, we find that mercury wet deposition is greater over high-elevation sites, seasonally during summer, and in convective precipitation.

  6. Organic micropollutants in wet and dry depositions in the Venice Lagoon.

    PubMed

    Gambaro, Andrea; Radaelli, Marta; Piazza, Rossano; Stortini, Angela Maria; Contini, Daniele; Belosi, Franco; Zangrando, Roberta; Cescon, Paolo

    2009-08-01

    Atmospheric transport is an important route by which pollutants are conveyed from the continents to both coastal and open sea. The role of aerosol deposition in the transport of polycyclic aromatic hydrocarbons (PAHs), polychlorobiphenyls (PCBs) and polybromodiphenyls ethers (PBDEs) to water and soil systems has been evaluated by measuring their concentrations in wet and dry depositions to the Venice Lagoon. The organic micropollutant flux data indicate that they contribute to the total deposition flux in different ways through wet and dry deposition, showing that the prevalent contribution derives from wet deposition. The fluxes calculated for PBDEs, showed the prevalence of 47, 99, 100 and 183 congeners, both in dry and wet fluxes. With regard to PCBs, the flux of summation operatorPCB for wet deposition is in the same order of magnitude of the diffusive flux at the air-water interface. The PAH fluxes obtained in the present study are similar to those obtained in previous studies on the atmospheric bulk deposition to the Venice Lagoon. The ratios between Phe/Ant and Fl/Py indicate that the pollutants sources are pyrolytic, deriving from combustion fuels.

  7. Development of a comprehensive testing framework for Lagrangian dispersion models: Application to wet deposition in FLEXPART

    NASA Astrophysics Data System (ADS)

    Philipp, Anne; Seibert, Petra

    2015-04-01

    Tasks such as inverse modelling and prediction of transport and dispersion of aerosols and soluble gases are increasingly performed by Lagrangian particle models, e.g. FLEXPART (FLEXible PARTicle dispersion model, http://flexpart.eu). Applications include decision making in situations of crisis. Therefore, the credibility in their results should be established through extensive evaluation. Because of this, we are currently developing a testing environment for FLEXPART. This environment is not only going to test the functionality of the model as a whole but also the functionality of its components such as, for example, wet deposition. Test cases and corresponding evaluation already created by FLEXPART developers in the past shall be brought together in this single environment, allowing for efficient testing of future code additions and modifications. Regression testing is being applied, meaning that the collection of test cases for all parts of the model is used to make sure that a change in one part of the model does not negatively affect the behavior of all the other parts, including overall runtime. One component of FLEXPART is the deposition scheme. Because particulate or particle-borne trace substances undergo wet as well as dry deposition, it is an important part of atmospheric transport modelling and it is a major influence factor for the atmospheric lifetime of aerosols and soluble gases. Therefore, we are presenting the development of our testing environment based on the example of the implementation of an improved wet deposition scheme in the latest FLEXPART version. Besides the usual software tests for assessing the functionality, performance and the structure-oriented work flow of the code, we have to show that the physical results of the deposition fields are realistic. The component of the testing environment for a new wet deposition scheme implemented in FLEXPART should compare its results with (i) measured deposition data, (ii) results from previous

  8. Composition of wet and bulk deposition in Erzurum, Turkey.

    PubMed

    Bayraktar, Hanefi; Turalioglu, F Sezer

    2005-06-01

    Seasonal variations in the chemical characteristics of wet and bulk deposition samples collected in Erzurum were investigated for the period March 2002-January 2003. Major cations (Ca2+, K+, Mg2+) and major anions (SO4(2-),NO3-) were determined in bulk and wet deposition samples; pH was also measured in wet deposition. The average pH of the wet deposition at Erzurum was 6.6 due to extensive neutralization of the acidity. A strong relationship between pH and SO4(2-) concentrations was observed in all seasons; however, only a weak relationship was found between pH and NO3-. On a seasonal basis, the correlation between Ca2+ and SO4(2-) concentrations was stronger in winter than in summer. Seasonal variations of ions were examined in both wet and bulk deposition samples. Although maximum concentrations of anions generally occurred during winter and spring, cation concentrations peaked in summer for both wet and bulk deposition. Results indicated that Ca2+ was the dominant cation and SO4(2-) the dominant anion in all deposition samples at Erzurum. Even though correlations among the crustal ions (calcium, magnesium and potassium) were high, the relationship between anthropogenic ions (sulfate and nitrate) was less clear in bulk deposition.

  9. Regional aerosol deposition in human upper airways

    SciTech Connect

    Swift, D.L.

    1991-11-01

    During the current report experimental studies of upper respiratory deposition of radon progeny aerosols and stimulant aerosols were carried out in replicate casts of nasal and oral passages of adults and children. Additionally, preliminary studies of nasal passage deposition of unattached Po{sup 218} particles was carried out in four human subjects. Data on nasal inspiratory deposition in replicate models of adults and infants from three collaborating laboratories were compared and a best-fit curve of deposition efficiency for both attached and unattached particles was obtained, showing excellent inter-laboratory agreement. This curve demonstrates that nasal inspiratory deposition of radon progeny is weakly dependent upon flow rate over physiologically realistic ranges of flow, does not show a significant age effect, and is relatively independent of nasal passage dimensions for a given age range. Improved replicate models of the human adult oral passage extending to the mid-trachea were constructed for medium and higher flow mouth breathing states; these models were used to assess the deposition of unattached Po{sup 218} particles during oronasal breathing in the oral passage and demonstrated lower deposition efficiency than the nasal passage. Measurements of both Po{sup 218} particle and attached fraction particle size deposition were performed in replicate nasal passage of a four week old infant. 5 refs., 1 fig.

  10. COMPARISONS OF SPATIAL PATTERNS OF WET DEPOSITION TO MODEL PREDICTIONS

    EPA Science Inventory

    The Community Multiscale Air Quality model, (CMAQ), is a "one-atmosphere" model, in that it uses a consistent set of chemical reactions and physical principles to predict concentrations of primary pollutants, photochemical smog, and fine aerosols, as well as wet and dry depositi...

  11. Dry and wet deposition of polycyclic aromatic hydrocarbons and comparison with typical media in urban system of Shanghai, China

    NASA Astrophysics Data System (ADS)

    Wang, Qing; Liu, Min; Li, Ye; Liu, Yankun; Li, Shuwen; Ge, Rongrong

    2016-11-01

    Polycyclic aromatic hydrocarbons (PAHs) were studied in dry and wet deposition samples collected at urban and suburban sites of Shanghai, China from April 2014 to April 2015. Average wet deposition fluxes of PAHs were higher than dry deposition (62.6 ± 41.5 vs. 26.9 ± 14.4 μg/m2/day). However, dry deposition removed more PAHs than wet deposition (69% vs. 31%) due to much shorter durations of wet deposition. The highest dry and wet deposition fluxes were in fall and winter, respectively. The highest amount of dry deposition was in fall and the highest of wet deposition was in summer. The contribution of wet deposition to total deposited PAHs in Shanghai, East China was higher than that in northern China and lower than that in southern China. The difference can be explained by both precipitation amount and removal efficiency (washout ratio). Average dry deposition velocity and washout ratio of particle-associated PAHs were 5.2 cm/s and 5.8 × 104, respectively. Four sources of deposited PAHs were unraveled by positive matrix factorization (PMF) model: traffic, coal combustion, coking and volatilization, contributing 28.7%, 24.6%, 23.7% and 23.0%, respectively. More contribution of traffic and less coal combustion and volatilization were found at urban than at suburban site. As the connection between aerosol and surface soil, deposition had a different PAH composition from those in the two sides, containing more low MW PAHs. That arose the concern that dry deposition velocity and particle washout ratio could be overestimated if coarse particulate matter was excluded from the calculation. Although deposition has been considered as the predominant pathway of PAHs to urban surface system, the PAH composition in street dust differed drastically from that in deposition. This indicated that other sources (e.g. traffic) in urban system could have a greater contribution to PAHs than it had been identified in deposition samples.

  12. Estimation and mapping of wet and dry mercury deposition across northeastern North America

    USGS Publications Warehouse

    Miller, E.K.; Vanarsdale, A.; Keeler, G.J.; Chalmers, A.; Poissant, L.; Kamman, N.C.; Brulotte, R.

    2005-01-01

    Whereas many ecosystem characteristics and processes influence mercury accumulation in higher trophic-level organisms, the mercury flux from the atmosphere to a lake and its watershed is a likely factor in potential risk to biota. Atmospheric deposition clearly affects mercury accumulation in soils and lake sediments. Thus, knowledge of spatial patterns in atmospheric deposition may provide information for assessing the relative risk for ecosystems to exhibit excessive biotic mercury contamination. Atmospheric mercury concentrations in aerosol, vapor, and liquid phases from four observation networks were used to estimate regional surface concentration fields. Statistical models were developed to relate sparsely measured mercury vapor and aerosol concentrations to the more commonly measured mercury concentration in precipitation. High spatial resolution deposition velocities for different phases (precipitation, cloud droplets, aerosols, and reactive gaseous mercury (RGM)) were computed using inferential models. An empirical model was developed to estimate gaseous elemental mercury (GEM) deposition. Spatial patterns of estimated total mercury deposition were complex. Generally, deposition was higher in the southwest and lower in the northeast. Elevation, land cover, and proximity to urban areas modified the general pattern. The estimated net GEM and RGM fluxes were each greater than or equal to wet deposition in many areas. Mercury assimilation by plant foliage may provide a substantial input of methyl-mercury (MeHg) to ecosystems. ?? 2005 Springer Science+Business Media, Inc.

  13. Impacts of Wet Scavenging Parameterizations on Global Simulations of Aerosol Concentrations and Lifetimes (Invited)

    NASA Astrophysics Data System (ADS)

    Croft, B.; Martin, R.; Lohmann, U.; Pierce, J. R.

    2013-12-01

    Wet scavenging processes strongly control aerosol three-dimensional distributions. In this study, we quantify the uncertainty in global simulations of aerosol vertical profiles and lifetimes, which may be attributed to uncertainties in both convective and stratiform wet scavenging parameterizations. For convective clouds, we show that different assumptions about the wet removal of aerosols entrained above convective cloud bases can yield differences of about one order of magnitude in middle and upper tropospheric aerosol concentrations. For stratiform clouds, we demonstrate the impact of size-dependent aerosol wet scavenging as compared to the use of fixed prescribed scavenging coefficients. We quantify the difference in simulated aerosol concentrations, particularly at high latitudes, yielded by different assumptions about scavenging in mixed phase and ice clouds. We also examine the sensitivity of simulated global mean aerosol lifetimes to parameterizations for wet scavenging. Global simulations of the scavenging of aerosol-bound radionuclides following the Fukushima Dai-Ichi nuclear power plant accident are also presented. The simulated radionuclide lifetimes are compared to measurements. We present an interpretation of these constraints on global mean aerosol lifetimes. The sensitivity of simulated aerosol-bound radionuclide lifetimes to altitude and location of the radionuclide injection is also examined with consideration to the interplay of aerosol transport, mixing, and removal processes.

  14. Precipitation chemistry and wet deposition in a remote wet savanna site in West Africa: Djougou (Benin)

    NASA Astrophysics Data System (ADS)

    Akpo, A. B.; Galy-Lacaux, C.; Laouali, D.; Delon, C.; Liousse, C.; Adon, M.; Gardrat, E.; Mariscal, A.; Darakpa, C.

    2015-08-01

    In the framework of the IDAF (IGAC/DEBITS/AFrica) international program, this study aims to study the chemical composition of precipitation and associated wet deposition at the rural site of Djougou in Benin, representative of a West and Central African wet savanna. Five hundred and thirty rainfall samples were collected at Djougou, Benin, from July 2005 to December 2009 to provide a unique database. The chemical composition of precipitation was analyzed for inorganic (Ca2+, Mg2+, Na+, NH4+, K+, NO3-, Cl-, SO42-) and organic (HCOO-, CH3COO-, C2H5COO-, C2O42-) ions, using ion chromatography. The 530 collected rain events represent a total of 5706.1 mm of rainfall compared to the measured pluviometry 6138.9 mm, indicating that the collection efficiency is about 93%. The order of total annual loading rates for soluble cations is NH4+ > Ca2+ > Mg2+ > K+. For soluble anions the order of loading is carbonates > HCOO- > NO3- > CH3COO- > SO4,SUP>2- > Cl- > C2O42- > C2H5COO-. In the wet savanna of Djougou, 86% of the measured pH values range between 4.7 and 5.7 with a median pH of 5.19, corresponding to a VWM (Volume Weighed Mean) H+ concentration of 6.46 μeq·L-1. This acidity results from a mixture of mineral and organic acids. The annual sea salt contribution was computed for K+, Mg2+, Ca2+ and SO42- and represents 4.2% of K+, 41% of Mg2+, 1.3% of Ca2+, and 7.4% of SO42-. These results show that K+, Ca2+, SO42-, and Mg2+ were mainly of non-marine origin. The marine contribution is estimated at 9%. The results of the chemical composition of rainwater of Djougou indicates that, except for the carbonates, ammonium has the highest VWM concentration (14.3 μeq·L-1) and nitrate concentration is 8.2 μeq·L-1. The distribution of monthly VWM concentration for all ions is computed and shows the highest values during the dry season, comparing to the wet season. Identified nitrogenous compound sources (NOx and NH3) are domestic animals, natural emissions from savanna soils

  15. METHODS OF CALCULATINAG LUNG DELIVERY AND DEPOSITION OF AEROSOL PARTICLES

    EPA Science Inventory


    Lung deposition of aerosol is measured by a variety of methods. Total lung deposition can be measured by monitoring inhaled and exhaled aerosols in situ by laser photometry or by collecting the aerosols on filters. The measurements can be performed accurately for stable monod...

  16. Simulated seasonal variations in wet acid depositions over East Asia.

    PubMed

    Ge, Cui; Zhang, Meigen; Zhu, Lingyun; Han, Xiao; Wang, Jun

    2011-11-01

    The air quality modeling system Regional Atmospheric Modeling System-Community Multi-scale Air Quality (RAMS-CMAQ) was applied to analyze temporospatial variations in wet acid deposition over East Asia in 2005, and model results obtained on a monthly basis were evaluated against extensive observations, including precipitation amounts at 704 stations and SO4(2-), NO3-, and NH4+ concentrations in the atmosphere and rainwater at 18 EANET (the Acid Deposition Monitoring Network in East Asia) stations. The comparison shows that the modeling system can reasonably reproduce seasonal precipitation patterns, especially the extensive area of dry conditions in northeast China and north China and the major precipitation zones. For ambient concentrations and wet depositions, the simulated results are in reasonable agreement (within a factor of 2) with observations in most cases, and the major observed features are mostly well reproduced. The analysis of modeled wet deposition distributions indicates that East Asia experiences noticeable variations in its wet deposition patterns throughout the year. In winter, southern China and the coastal areas of the Japan Sea report higher S04(2-) and NO3- wet depositions. In spring, elevated SO4(2-) and NO3-wet depositions are found in northeastern China, southern China, and around the Yangtze River. In summer, a remarkable rise in precipitation in northeastern China, the valleys of the Huaihe and Yangtze rivers, Korea, and Japan leads to a noticeable increase in SO4(2-) and NO3- wet depositions, whereas in autumn, higher SO4(2-) and NO3-wet depositions are found around Sichuan Province. Meanwhile, due to the high emission of SO2, high wet depositions of SO4(2-) are found throughout the entire year in the area surrounding Sichuan Province. There is a tendency toward decreasing NO3- concentrations in rainwater from China through Korea to Japan in both observed and simulated results, which is a consequence of the influence of the continental

  17. Chamber for Aerosol Deposition of Bioparticles

    NASA Technical Reports Server (NTRS)

    Kern, Roger; Kirschner, Larry

    2008-01-01

    Laboratory apparatus is depicted that is a chamber for aerosol deposition of bioparticles on surfaces of test coupons. It is designed for primary use in inoculating both flat and three-dimensional objects with approximately reproducible, uniform dispersions of bacterial spores of the genus Bacillus so that the objects could be used as standards for removal of the spores by quantitative surface sampling and/or cleaning processes. The apparatus is also designed for deposition of particles other than bacterial spores, including fungal spores, viruses, bacteriophages, and standard micron-sized beads. The novelty of the apparatus lies in the combination of a controllable nebulization system with a settling chamber large enough to contain a significant number of test coupons. Several companies market other nebulizer systems, but none are known to include chambers for deposition of bioparticles to mimic the natural fallout of bioparticles. The nebulization system is an expanded and improved version of commercially available aerosol generators that include nebulizers and drying columns. In comparison with a typical commercial aerosol generator, this system includes additional, higher-resolution flowmeters and an additional pressure regulator. Also, unlike a typical commercial aerosol generator, it includes stopcocks for separately controlling flows of gases to the nebulizer and drying column. To maximize the degree of uniformity of dispersion of bioaerosol, the chamber is shaped as an axisymmetrical cylinder and the aerosol generator is positioned centrally within the chamber and aimed upward like a fountain. In order to minimize electric charge associated with the aerosol particles, the drying column is made of aluminum, the drying column is in direct contact with an aluminum base plate, and three equally spaced Po-210 antistatic strips are located at the exit end of the drying column. The sides and top of the chamber are made of an acrylic polymer; to prevent

  18. Aerosol deposition in the human respiratory tract

    NASA Astrophysics Data System (ADS)

    Winchester, John W.; Jones, Donald L.; Mu-tian, Bi

    1984-04-01

    Rising sulfur dioxide emissions from increased coal combustion present risks, not only of acid rain, but also to health by inhalation of the SO 2 and acid to the lung. We are investigating human inhalation of ppm SO 2 concentrations mixed with aerosol of submicrometer aqueous salt droplets to determine the effects on lung function and body chemistry. Unlike some investigators, we emphasize ammonium sulfate and trace element aerosol composition which simulates ambient air; aerosol pH, relative humidity, and temperature control to reveal gas-particle reaction mechanisms; and dose estimates from length of exposure, SO 2 concentration, and a direct measurement of respiratory deposition of aerosol as a function of particle size by cascade impactor sampling and elemental analysis by PIXE. Exposures, at rest or during exercise, are in a walk-in chamber at body temperature and high humidity to simulate Florida's summer climate. Lung function measurement by spirometry is carried out immediately after exposure. The results are significant in relating air quality to athletic performance and to public health in the southeastern United States.

  19. Aerosol deposition in bends with turbulent flow

    SciTech Connect

    McFarland, A.R.; Gong, H.; Wente, W.B.

    1997-08-01

    The losses of aerosol particles in bends were determined numerically for a broad range of design and operational conditions. Experimental data were used to check the validity of the numerical model, where the latter employs a commercially available computational fluid dynamics code for characterizing the fluid flow field and Lagrangian particle tracking technique for characterizing aerosol losses. Physical experiments have been conducted to examine the effect of curvature ratio and distortion of the cross section of bends. If it curvature ratio ({delta} = R/a) is greater than about 4, it has little effect on deposition, which is in contrast with the recommendation given in ANSI N13.1-1969 for a minimum curvature ratio of 10. Also, experimental results show that if the tube cross section is flattened by 25% or less, the flattening also has little effect on deposition. Results of numerical tests have been used to develop a correlation of aerosol penetration through a bend as a function of Stokes number (Stk), curvature ratio ({delta}) and the bend angle ({theta}). 17 refs., 10 figs., 2 tabs.

  20. Endosulfan wet deposition in Southern Florida

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The atmosphere is an important transport route for semi-volatile pesticides like endosulfan. Deposition, which depends on physical-chemical properties, use patterns, and climatic conditions, can occur at local, regional, and global scales. Adverse human and ecological impact may result. We measured...

  1. Wet deposition and snowpack monitoring. Final project report. Project summary

    SciTech Connect

    Hess, B.C.; Rocchio, J.E.; Chaloud, D.J.; Arent, L.J.; Engels, J.L.

    1988-04-01

    Accurate measurement of snowfall is critical to the assessment of acidic deposition trends, particularly in areas where snow represents 30 percent or more of the annual precipitation. Such areas include the intermountain west, where complex topography and meteorology, heavy precipitation, and extreme cold. Instruments selected for evaluation included the Aerochem Metrics Model 301 wet/dry deposition collector, the Belfort Model 5-780 weighing rain gage, and the U.S. Geological Survey designed 46-cm bulk samplers.

  2. New insights into trace element wet deposition in the Himalayas: amounts, seasonal patterns, and implications.

    PubMed

    Cong, Zhiyuan; Kang, Shichang; Zhang, Yulan; Gao, Shaopeng; Wang, Zhongyan; Liu, Bin; Wan, Xin

    2015-02-01

    Our research provides the first complete year-long dataset of wet deposition of trace elements in the high Himalayas based on a total of 42 wet deposition events on the northern slope of Mt. Qomolangma (Everest). Except for typical crustal elements (Al, Fe, and Mn), the concentration level of most trace elements (Sc, V, Cr, Co, Ni, Cu, Zn, As, Mo, Cd, Sn, Cs, Pb, Bi, and U) are generally comparable to those preserved in snow pits and ice cores from the nearby East Rongbuk Glacier. Cadmium was the element most affected by anthropogenic emissions. No pronounced seasonal variations are observed for most trace elements despite different transport pathways. In our study, the composition of wet precipitation reflects a regional background condition and is not clearly related to specific source regions. For the trace element record from ice cores and snow pits in the Himalayas, it could be deduced that the pronounced seasonal patterns were caused by the dry deposition of trace elements (aerosols) during their long exposure to the atmosphere after precipitation events. Our findings are of value for the understanding of the trace element deposition mechanisms in the Himalayas.

  3. Aerosol deposition and origin in French mountains estimated with soil inventories of 210Pb and artificial radionuclides

    NASA Astrophysics Data System (ADS)

    Le Roux, Gaël; Pourcelot, Laurent; Masson, Olivier; Duffa, Céline; Vray, Françoise; Renaud, Philippe

    Radionuclide inventories were measured in soils from different French mountainous areas: Chaîne des Puys (Massif Central), Eastern Corsica, Jura, Montagne Noire, Savoie, Vosges and Rhine Valley. 210Pb soil inventories were used to estimate long-term (>75 yr) deposition of submicron aerosols. Whereas 210Pb total deposition is explained partly by wet deposition, as demonstrated by increase of 210Pb inventory with annual rainfall; a part of 210Pb in the soils of higher altitude is caused by orographic depositions. Using measurements of radionuclides coming from nuclear aerial weapon tests ( 137Cs and Pu isotopes), we were able to estimate the origin of aerosols deposited in high-altitude sites and to confirm the importance of occult deposition and feeder-seeder mechanism. Using a simple mass balance model, we estimate that occult deposition and feeder-seeder mechanisms account to more than 50% of total deposition of 210Pb and associated submicron aerosols in French altitude sites.

  4. Sources of mercury wet deposition in Eastern Ohio, USA.

    PubMed

    Keeler, Gerald J; Landis, Matthew S; Norris, Gary A; Christianson, Emily M; Dvonch, J Timothy

    2006-10-01

    In the fall of 2002, an enhanced air monitoring site was established in Steubenville, Ohio as part of a multi-year comprehensive mercury monitoring and source apportionment study to investigate the impact of local and regional coal combustion sources on atmospheric mercury deposition in the Ohio River Valley. This study deployed advanced monitoring instrumentation, utilized innovative analytical techniques, and applied state-of-the-art statistical receptor models. This paper presents wet deposition data and source apportionment modeling results from daily event precipitation samples collected during the calendar years 2003-2004. The volume-weighted mean mercury concentrations for 2003 and 2004 were 14.0 and 13.5 ng L(-1), respectively, and total annual mercury wet deposition was 13.5 and 19.7 microg m(-2), respectively. Two new EPA-implemented multivariate statistical models, positive matrix factorization (PMF) and Unmix, were applied to the data set and six sources were identified. The dominant contributor to the mercury wet deposition was found by both models to be coal combustion (approximately 70%). Meteorological analysis also indicated that a majority of the mercury deposition found at the Steubenville site was due to local and regional sources.

  5. Aerosol chemistry during the wet season in central Amazonia - The influence of long-range transport

    NASA Technical Reports Server (NTRS)

    Talbot, R. W.; Andreae, M. O.; Berresheim, H.; Artaxo, P.; Garstang, M.

    1990-01-01

    The temporal variation in the concentration and chemistry of the atmospheric aerosol over central Amazonia, Brazil, during the 1987 wet season is discussed based on ground and aircraft collected data obtained during the NASA GTE ABLE 2B expedition conducted in April/May 1987. It is found that wet-season aerosol concentrations and composition are variable in contrast to the more uniform biogenic aerosol observed during the 1985 dry season; four distinct intervals of enhanced aerosol concentration coincided with short periods (3 to 5 d) of extensive rainfall. It is hypothesized that aerosol chemistry in Amazonia during the wet season is strongly influenced by long-range transport of soil dust, marine aerosol, and possibly biomass combustion products advected into the central Basin by large-scale tropospheric circulation, producing periodic pulses of material input to local boundary layer air. The resultant wet-season aerosol regime is dynamic, in contrast to the uniformity of natural biogenic aerosols during the dry season.

  6. 1986 wet deposition temporal and spatial patterns in North America

    SciTech Connect

    Olsen, A.R.

    1989-07-01

    The focus of this report is on North American wet deposition temporal patterns from 1979 to 1986 and spatial patterns for 1986. The report provides statistical distribution summaries of annual precipitation-weighted average concentration and annual deposition for nine ion species: hydrogen, sulfate, nitrate, ammonium, calcium, chloride, sodium, potassium, and magnesium. The data in the report are from the Acid Depositing System (ADS) for the statistical reporting of North American deposition data. Isopleth maps, based on surface estimation using kriging, display concentration and deposition spatial patterns of pH, hydrogen, sulfate, nitrate, ammonium, and calcium ion species for 1986 annual, winter, and summer periods. The temporal pattern analyses use a subset of 30 sites over an 8-year (1979-1986) period and an expanded subset of 137 sites with greater spatial coverage over a 5-year (1982-1986) period. The 8-year period represents the longest period with wet deposition monitoring data unavailable that has a sufficient number of sites with data of known quality to allow a descriptive summary of annual temporal patterns. 19 refs., 105 figs., 29 tabs.

  7. The Various Influences due to Aerosol Depositions

    NASA Technical Reports Server (NTRS)

    Yasunari, Teppei

    2011-01-01

    Recently the issue on glacier retreats comes up and many factors should be relevant to the issue. The absorbing aerosols such as dust and black carbon (BC) are considered to be one of the factors. After they deposited onto the snow surface, it will reduce snow albedo (called snow darkening effect) and probably contribute to further melting of glacier. The Goddard Earth Observing System version 5 (GEOS-5) has developed at NASA/GSFC. However, the original snowpack model used in the land surface model in the GEOS-5 did not consider the snow darkening effect. Here we developed the new snow albedo scheme which can consider the snow darkening effect. In addition, another scheme on calculating mass concentrations on the absorbing aerosols in snowpack was also developed, in which the direct aerosol depositions from the chemical transport model in the GEOS-5 were used. The scheme has been validated with the observed data obtained at backyard of the Institute of Low Temperature Science, Hokkaido University, by Dr. Teruo Aoki (Meteorological Research Institute) et al. including me. The observed data was obtained when I was Ph.D.caftdidate. The original GEOS-5 during 2007-2009 over the Himalayas and Tibetan Plateau region showed more reductions of snow than that of the new GEOS-5 because the original one used lower albedo settings. On snow cover fraction, the new GEOS-5 simulated more realistic snow-covered area comparing to the MODIS snow cover fraction. The reductions on snow albedo, snow cover fraction, and snow water equivalent were seen with statistically significance if we consider the snow darkening effect comparing to the results without the snow darkening effect. In the real world, debris cover, inside refreezing process, surface flow of glacier, etc. affect glacier mass balance and the simulated results immediately do not affect whole glacier retreating. However, our results indicate that some surface melting over non debris covered parts of the glacier would be

  8. 1988 Wet deposition temporal and spatial patterns in North America

    SciTech Connect

    Simpson, J.C.; Olsen, A.R.; Bittner, E.A.

    1992-03-01

    The focus of this report is on North American wet deposition temporal patterns from 1979 to 1988 and spatial patterns for 1988. It is the third in a series of reports that investigate the patterns of annual precipitation-weighted average concentration and annual deposition for nine ion species: hydrogen, sulfate, nitrate, ammonium, calcium, chloride, sodium, potassium, and magnesium. Mosaic maps, based on surface estimation using kriging, display concentration and deposition spatial patterns of pH, hydrogen, sulfate, nitrate, ammonium, and calcium ion species for 1988 annual, winter, and summer periods. Temporal pattern analyses use a subset of 35 sites over a 10-year (1979--1988) period and an expanded subset of 137 sites, with greater spatial coverage, over a 7-year (1982--1988) period. The 10-year period represents the longest period with wet deposition monitoring data available that has a sufficient number of sites with data of known quality to allow a descriptive summary of annual temporal patterns. Sen's median trend estimate and Kendall's seasonal tau (KST) test are calculated for each ion species concentration and deposition at each site in both subsets.

  9. 1988 Wet deposition temporal and spatial patterns in North America

    SciTech Connect

    Simpson, J.C.; Olsen, A.R.; Bittner, E.A.

    1992-03-01

    The focus of this report is on North American wet deposition temporal patterns from 1979 to 1988 and spatial patterns for 1988. It is the third in a series of reports that investigate the patterns of annual precipitation-weighted average concentration and annual deposition for nine ion species: hydrogen, sulfate, nitrate, ammonium, calcium, chloride, sodium, potassium, and magnesium. Mosaic maps, based on surface estimation using kriging, display concentration and deposition spatial patterns of pH, hydrogen, sulfate, nitrate, ammonium, and calcium ion species for 1988 annual, winter, and summer periods. Temporal pattern analyses use a subset of 35 sites over a 10-year (1979--1988) period and an expanded subset of 137 sites, with greater spatial coverage, over a 7-year (1982--1988) period. The 10-year period represents the longest period with wet deposition monitoring data available that has a sufficient number of sites with data of known quality to allow a descriptive summary of annual temporal patterns. Sen`s median trend estimate and Kendall`s seasonal tau (KST) test are calculated for each ion species concentration and deposition at each site in both subsets.

  10. Variation of wet deposition chemistry in Sequoia National Park, California

    USGS Publications Warehouse

    Stohlgren, Thomas J.; Parsons, David J.

    1987-01-01

    Sequoia National Park has monitored wet deposition chemistry in conjunction with the National Atmospheric Deposition Program and National Trends Network (NADP/NTN), on a weekly basis since July, 1980. Annual deposition of H, NO3 and SO4 (0.045, 3.6, and 3.9 kg ha−1 a−1, respectively) is relatively low compared to that measured in the eastern United States, or in the urban Los Angeles and San Francisco areas. Weekly ion concentrations are highly variable. Maximum concentrations of 324,162, and 156 μeq ol−1 of H, NO3 and SO4 have been recorded for one low volume summer storm (1.4 mm). Summer concentrations of NO3 and SO4 average two and five times higher, respectively, than concentrations reported for remote areas in the world. There is considerable variability in the ionic concentration of low volume samples, and much less variability in moderate and high volume samples.

  11. Effects of wet deposition on optical properties of the atmosphere over Bermuda and Barbados

    NASA Astrophysics Data System (ADS)

    Todd, Deborah L.; Keene, William C.; Moody, Jennie L.; Maring, Hal; Galloway, James N.

    2003-02-01

    Substantial spatial and temporal variabilities in chemical and physical properties of aerosols complicate attempts to model associated influences on global climate. Although wet deposition is the major mechanism by which most aerosols are removed from the atmosphere, direct effects of precipitation on radiative properties of the atmosphere are not well understood. To address this issue, attenuation coefficients for total insoluble constituents (ACt) and for nonvolatile (at 500°C) insoluble constituents (ACnv; primarily crustal dust) of precipitation at Bermuda and Barbados were measured at six wavelengths between 414 and 859 nm. Coefficients for volatile (at 500°C) insoluble constituents (ACv; primarily carbonaceous species) were calculated by difference. Between April and September, ACt at Bermuda was dominated by mineral constituents transported from North Africa, whereas carbonaceous species from North America were relatively low and exhibited no systematic seasonal variability. ACt and ACnv at Barbados were dominated by mineral dust, especially between April and September. Relative to ACv, ACnv decreased more rapidly with increasing wavelength. The wavelength dependencies of ACs for volatile and nonvolatile constituents at Bermuda were statistically indistinguishable from those at Barbados. The optical and chemical characteristics of precipitation were compared with scattering and absorption by ambient aerosols in associated air parcels to evaluate the influence of scavenging on the radiative properties of air. Although discernible relationships were evident, the small number of cases limited their applicability as reliable empirical predictors. However, these data do provide useful constraints for validating models of aerosol scavenging and wet removal on the optical properties of the troposphere.

  12. Aerosol Deposition in the Human Lung in Reduced Gravity

    PubMed Central

    2014-01-01

    Abstract The deposition of aerosol in the human lung occurs mainly through a combination of inertial impaction, gravitational sedimentation, and diffusion. For 0.5- to 5-μm-diameter particles and resting breathing conditions, the primary mechanism of deposition in the intrathoracic airways is sedimentation, and therefore the fate of these particles is markedly affected by gravity. Studies of aerosol deposition in altered gravity have mostly been performed in humans during parabolic flights in both microgravity (μG) and hypergravity (∼1.6G), where both total deposition during continuous aerosol mouth breathing and regional deposition using aerosol bolus inhalations were performed with 0.5- to 3-μm particles. Although total deposition increased with increasing gravity level, only peripheral deposition as measured by aerosol bolus inhalations was strongly dependent on gravity, with central deposition (lung depth<200 mL) being similar between gravity levels. More recently, the spatial distribution of coarse particles (mass median aerodynamic diameter≈5 μm) deposited in the human lung was assessed using planar gamma scintigraphy. The absence of gravity caused a smaller portion of 5-μm particles to deposit in the lung periphery than in the central region, where deposition occurred mainly in the airways. Indeed, 5-μm-diameter particles deposit either by inertial impaction, a mechanism most efficient in the large and medium-sized airways, or by gravitational sedimentation, which is most efficient in the distal lung. On the contrary, for fine particles (∼1 μm), both aerosol bolus inhalations and studies in small animals suggest that particles deposit more peripherally in μG than in 1G, beyond the reach of the mucociliary clearance system. PMID:24870702

  13. Deposition of Aerosols in the Lung: Physiological Factors

    EPA Science Inventory

    Ventilation and mechanics of breathing are an integral part of respiratory physiology that directly affect aerosol transport and deposition in the lung. Although natural breathing pattern varies widely among individuals, breathing pattern is controllable, and by using an appropri...

  14. 1987 wet deposition temporal and spatial patterns in North America

    SciTech Connect

    Simpson, J.C.; Olsen, A.R.

    1990-03-01

    The focus of this report is on North American wet deposition temporal patterns from 1979 to 1987 and spatial patterns for 1987. The report investigates the patterns of annual precipitation-weighted average concentration and annual deposition for nine ion species: hydrogen, sulfate, nitrate, ammonium, calcium, chloride, sodium, potassium, and magnesium. Data are from the Acid Deposition System (ADS) for the statistical reporting of North American deposition data which includes the National Atmospheric Deposition Program/National Trends Network (NADP/NTN), the MAP3S precipitation chemistry network, the Utility Acid Precipitation Study Program (UAPSP), the Canadian Precipitation Monitoring Network (CAPMoN), and the daily and 4-weekly Acidic Precipitation in Ontario Study (APIOS-D and APIOS-C). Mosaic maps, based on surface estimation using kriging, display concentration and deposition spatial patterns of pH, hydrogen, sulfate, nitrate, ammonium, and calcium ion species for 1987 annual, winter, and summer periods. The temporal pattern analyses use a subset of 39 sites over a 9-year (1979--1987) period and an expanded subset of 140 sites with greater spatial coverage over a 6-year (1982--1987) period. 68 refs., 15 figs., 15 tabs.

  15. Photochemistry of Glyoxal in Wet Aerosols: Smog Chamber Study

    NASA Astrophysics Data System (ADS)

    Lim, Y. B.; Kim, H.; Turpin, B. J.

    2015-12-01

    Aqueous chemistry is an important pathway for the formation of secondary organic aerosol (SOA). Reaction vessel studies provide evidence that in the aqueous phase photooxidation of water soluble organic compounds (e.g., glyoxal, methylglyoxal) form multifunctional organic products and oligomers. In this work, we extend this bulk-phase chemistry to the condensed-phase chemistry that occurs in/on aerosols by conducting smog chamber experiments — photooxidation of ammonium sulfate and sulfuric acid aerosols containing glyoxal and hydrogen peroxide in the presence of NOx under dry/humid conditions. Particles were analyzed using ultra performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS). In the irradiated chamber, photooxidation products of glyoxal as seen in reaction vessel experiments (e.g., oxalic acids and tartaric acids) were also formed in both ammonium sulfate aerosols and sulfuric acid aerosols at humid and even dry conditions. However, the major products were organosulfurs (CHOS), organonitrogens (CHON), and nitrooxy-organosulfates (CHONS), which were also dominantly formed in the dark chamber. These products were formed via non-radical reactions, which depend on acidity and humidity. However, the real-time profiles in the dark chamber and the irradiated chamber were very different, suggesting photochemistry substantially affects non-radical formation in the condensed phase.

  16. Deposition and retention of radioactive aerosols on desert vegetation

    SciTech Connect

    Millard, G.E.

    1986-01-01

    Deposition velocities and retention times were obtained for submicron aerosols of /sup 134/Cs and /sup 141/Ce on a shrub species (Artemisia tridentata) and a grass (Elymus elimoides) in a natural desert environment. Submicron aerosols of these two nuclides were artificially generated and released over a sagebrush community in southeast Idaho during each of three seasons: spring, summer and winter, to determine the effects of weathering and plant development on aerosol deposition and retention. Information on friction velocities, roughness lengths, and particle size was also obtained.

  17. Wet deposition of the seeding agent after weather modification activities.

    PubMed

    Curić, Mladjen; Janc, Dejan

    2013-09-01

    Weather modification activities are performed mostly by cloud seeding. Some operational projects have been conducted for more than a half century and cover planetary scales. These activities have led to large amounts of seeding agents being deposited on the ground in precipitation. The main intent of this paper is to identify the spatial pattern of silver iodide deposits after hail suppression. The spatial pattern of silver iodide deposits is determined using the weather modification project measurements from seeding agent reports, two weather radars and 316 launching sites during a 5-year period. The estimated spatial distribution of the deposits is not uniform, with the maximum silver iodide amount located in the southern part of the study area (up to 140 μg m(-2)). Our results are comparable with the measurements performed by chemical analyses during other cloud seeding experiments. The maximum location coincides well with that of the maximum seeded hailstorm precipitation frequency. A new method for identifying the spatial pattern of wet-deposited material has been established. The location with the maximum amount is found. This method would be important as a means of placing samplers and monitoring at the representative sites because those are where most weather modification projects would be performed in the future.

  18. Regional aerosol deposition in human upper airways. Final report

    SciTech Connect

    Swift, D.L.

    1997-11-01

    During the award period, a number of studies have been carried out related to the overall objective of the project which is to elucidate important factors which influence the upper airway deposition and dose of particles in the size range 0.5 nm - 10 {mu}m, such as particle size, breathing conditions, age, airway geometry, and mode of breathing. These studies are listed below. (1) A high voltage electrospray system was constructed to generate polydispersed 1-10 {mu}m diameter di-ethylhexyl sebacate aerosol for particle deposition studies in nasal casts and in human subjects. (2) The effect of nostril dimensions, nasal passage geometry, and nasal resistance on particle deposition efficiency in forty healthy, nonsmoking adults at a constant flowrate were studied. (3) The effect of nostril dimensions, nasal passage dimensions and nasal resistance on the percentage of particle deposition in the anterior 3 cm of the nasal passage of spontaneously breathing humans were studied. (4) The region of deposition of monodispersed aerosols were studied using replicate casts. (5) Ultrafine aerosol deposition using simulated breath holding path and natural path was compared. (6) An experimental technique was proposed and tested to measure the oral deposition of inhaled ultrafine particles. (7) We have calculated the total deposition fraction of ultrafine aerosols from 5 to 200 n in the extrathoracic airways and in the lung. (8) The deposition fraction of radon progeny in the head airways was studied using several head airway models.

  19. The use of bulk collectors in monitoring wet deposition at high-altitude sites in winter

    USGS Publications Warehouse

    Ranalli, A.J.; Turk, J.T.; Campbell, D.H.

    1997-01-01

    Concentrations of dissolved ions from samples collected by wet/dry collectors were compared to those collected by bulk collectors at Halfmoon Creek and Ned Wilson Lake in western Colorado to determine if bulk collectors can be used to monitor wet deposition chemistry in remote, high-altitude regions in winter. Hydrogen-ion concentration was significantly lower (p 0.05) at Halfmoon Creek. Wet deposition concentrations were predicated from bulk deposition concentrations through linear regression analysis. Results indicate that anions (chloride, nitrate and sulfate) can be predicted with a high degree of confidence. Lack of significant differences between seasonal (winter and summer) ratios of bulk to wet deposition concentrations indicates that at sites where operation of a wet/dry collector during the winter is not practical, wet deposition concentrations can be predicted from bulk collector samples through regression analysis of wet and bulk deposition data collected during the summer.

  20. Recent bright gully deposits on Mars: Wet or dry flow?

    USGS Publications Warehouse

    Pelletier, J.D.; Kolb, K.J.; McEwen, A.S.; Kirk, R.L.

    2008-01-01

    Bright gully sediments attributed to liquid water flow have been deposited on Mars within the past several years. To test the liquid water flow hypothesis, we constructed a high-resolution (1 m/pixel) photogrammetric digital elevation model of a crater in the Centauri Montes region, where a bright gully deposit formed between 2001 and 2005. We conducted one-dimensional (1-D) and 2-D numerical flow modeling to test whether the deposit morphology is most consistent with liquid water or dry granular How. Liquid water flow models that incorporate freezing can match the runout distance of the flow for certain freezing rates but fail to reconstruct the distributary lobe morphology of the distal end of the deposit. Dry granular flow models can match both the observed runout distance and the distal morphology. Wet debris flows with high sediment concentrations are also consistent with the observed morphology because their rheologies are often similar to that of dry granular flows. As such, the presence of liquid water in this flow event cannot be ruled out, but the available evidence is consistent with dry landsliding. ?? 2008 The Geological Society of America.

  1. Pulmonary deposition of aerosols by different mechanical devices.

    PubMed

    Matthys, H; Köhler, D

    1985-01-01

    With a new method for easy labeling of beta 2-agonists we measured intra- and extrapulmonary aerosol deposition after the administration of a bolus from a metered-dose inhaler at residual volume (RV) inhaling after a pause of 2 s and after immediate administration into the inspiratory flow at functional residual capacity (FRC). Immediate administration during a slow inspiratory vital capacity maneuver gives the highest intrapulmonary deposition (30-40%). Compressed air and ultrasonic nebulizers with a particle distribution pattern of 2-5 micron aerodynamic mass median diameter (AMMD) allow in normal subjects to achieve an intrapulmonary deposition of 30-60% during standardized tidal breathing at rest, the magnitude of the deposition depending mainly on each subject's larynx geometry. The outlet system leads to different deposition patterns in aerosol generators with the same AMMD. Many commercially available aerosol generators do not fulfill the criteria for any intrapulmonary aerosol deposition. For drug administration into the lungs, condensation aerosol generators ('steam boiler nebulizers') are useless as well as compressed-air, ultrasonic and steam driven nebulizers with a particle size of more than 10 micron AMMD.

  2. Preparation of Thick Magnet Films by the Aerosol Deposition Method

    NASA Astrophysics Data System (ADS)

    Sugimoto, Satoshi

    The aerosol deposition method (ADM) is effective for the preparation of thick films with high deposition rate. We applied this method to fabricate NiZn ferrite or Sm-Fe-N films, which are used for microwave absorbers or permanent magnets, respectively. In this article, the magnetic properties of Sm-Fe-N thick films fabricated by the ADM are introduced and the possibility of the ADM for the fabrication process with high deposition rate is discussed.

  3. Sensitivity of depositions to the size and hygroscopicity of Cs-bearing aerosols released from the Fukushima nuclear accident

    NASA Astrophysics Data System (ADS)

    Kajino, Mizuo; Adachi, Kouji; Sekiyama, Tsuyoshi; Zaizen, Yuji; Igarashi, Yasuhito

    2014-05-01

    We recently revealed that the microphysical properties of aerosols carrying the radioactive Cs released from the Fukushima Daiichi Nuclear Power Plant (FDNPP) at an early stage (March 14-15, 2011) of the accident could be very different from what we assumed previously: super-micron and non-hygroscopic at the early stage, whereas sub-micron and hygroscopic afterwards (at least later than March 20-22). In the study, two sensitivity simulations with the two different aerosol microphysical properties were conducted using a regional scale meteorology- chemical transport model (NHM-Chem). The impact of the difference was quite significant. 17% (0.001%) of the radioactive Cs fell onto the ground by dry (wet) deposition processes, and the rest was deposited into the ocean or was transported out of the model domain, which is central and northern part of the main land of Japan, under the assumption that Cs-bearing aerosols are non-hygroscopic and super-micron. On the other hand, 5.7% (11.3%) fell onto the ground by dry (wet) deposition, for the cases under the assumption that the Cs-bearing aerosols are hygroscopic and sub-micron. For the accurate simulation of the deposition of radionuclides, knowledge of the aerosol microphysical properties is essential as well as the accuracy of the simulated wind fields and precipitation patterns.

  4. Laboratory measurements of parameters affecting wet deposition of methyl iodide

    SciTech Connect

    Maeck, W.J.; Honkus, R.J.; Keller, J.H.; Voilleque, P.G.

    1984-09-01

    The transfer of gaseous methyl iodide (CH/sub 3/I) to raindrops and the initial retention by vegetation of CH/sub 3/I in raindrops have been studied in a laboratory experimental program. The measured air-to-drop transfer parameters and initial retention factors both affect the wet deposition of methyl iodide onto vegetation. No large effects on the air-to-drop transfer due to methyl iodide concentration, temperature, acidity, or rain type were observed. Differences between laboratory measurements and theoretical values of the mass transfer coefficient were found. Pasture grass, lettuce, and alfalfa were used to study the initial retention of methyl iodide by vegetation. Only a small fraction of the incident CH/sub 3/I in raindrops was held by any of the three vegetation types.

  5. Modeling investigation of light-absorbing aerosols in the Amazon Basin during the wet season

    NASA Astrophysics Data System (ADS)

    Wang, Qiaoqiao; Saturno, Jorge; Chi, Xuguang; Walter, David; Lavric, Jost V.; Moran-Zuloaga, Daniel; Ditas, Florian; Pöhlker, Christopher; Brito, Joel; Carbone, Samara; Artaxo, Paulo; Andreae, Meinrat O.

    2016-11-01

    We use a global chemical transport model (GEOS-Chem) to interpret observed light-absorbing aerosols in Amazonia during the wet season. Observed aerosol properties, including black carbon (BC) concentration and light absorption, at the Amazon Tall Tower Observatory (ATTO) site in the central Amazon have relatively low background levels but frequently show high peaks during the study period of January-April 2014. With daily temporal resolution for open fire emissions and modified aerosol optical properties, our model successfully captures the observed variation in fine/coarse aerosol and BC concentrations as well as aerosol light absorption and its wavelength dependence over the Amazon Basin. The source attribution in the model indicates the important influence of open fire on the observed variances of aerosol concentrations and absorption, mainly from regional sources (northern South America) and from northern Africa. The contribution of open fires from these two regions is comparable, with the latter becoming more important in the late wet season. The analysis of correlation and enhancement ratios of BC versus CO suggests transport times of < 3 days for regional fires and ˜ 11 days for African plumes arriving at ATTO during the wet season. The model performance of long-range transport of African plumes is also evaluated with observations from AERONET, MODIS, and CALIOP. Simulated absorption aerosol optical depth (AAOD) averaged over the wet season is lower than 0.0015 over the central Amazon, including the ATTO site. We find that more than 50 % of total absorption at 550 nm is from BC, except for the northeastern Amazon and the Guianas, where the influence of dust becomes significant (up to 35 %). The brown carbon contribution is generally between 20 and 30 %. The distribution of absorption Ångström exponents (AAE) suggests more influence from fossil fuel combustion in the southern part of the basin (AAE ˜ 1) but more open fire and dust influence in the

  6. Aerosol deposition in human respiratory-tract casts

    SciTech Connect

    Martonen, T.B.

    1981-09-01

    To assess the health hazard to the human presented by airborne particulate matter in the mining and industrial work environment, information is needed concerning total dose deposition and its distribution. Data has been obtained by depositing monodisperse ammonium fluorscein aerosols in respiratory system simulators consisting of combined human replica larynx casts and single-pathway trachebronchial (TB) tue models. Since they have only two airways in each generation distal to the trachea, airflow rates and patterns could be controlled in a practical manner with rotometers. Larynx configurations correspond to inspiratory flow rates of 15, 30 and 60 lmin. The mass median aerodynamic diameters of the aerosols ranged from 3.0 ..mu..m to 10.6 ..mu..m with geometric standard deviations of 1.11 to 1.16. Total larynx and TB deposition measurements could be expressed in terms of a single parameter, the particle Stokes number. Intrabronchial dose distribution results indicated relatively large tracheal losses, attributed to the laryngeal jet. Some airway bifurcations were sites of enhanced deposition. Such hot spots would indicate very high dosage to epithelial cells of workers' airways and have important implications regarding the establishment of threshold exposure values. Findings are in agreement with aerosol deposition data from replica TB casts. Inhalation exposure tests support the use of the single-pathway TB model as a suitable surrogate in studies of factors affecting aerosol behavior and deposition in the human.

  7. Challenges in validating CFD-derived inhaled aerosol deposition predictions.

    PubMed

    Oldham, Michael J

    2006-09-01

    Computational fluid dynamic (CFD) techniques have provided unprecedented opportunity for investigating inhaled particle deposition in realistic human airway geometries. Several recent articles describing local aerosol deposition predictions based upon "validated" CFD models have highlighted the challenges in validating local aerosol deposition predictions. These challenges include: (1) defining what is meant by validation; (2) defining appropriate experimental data for validation; and (3) determining when the agreement is not fortuitous. The term validation has numerous meanings, depending on the field and context in which it is used. For example, in computer programming it means the code executes as intended, to the experimentalist it means predicted results agree with matched experimental measurements, and to the risk assessor it implies that predictions using new parameters can be trusted. Based on the current literature it is not clear that a consensus exists for what constitutes a validated CFD model. It is also not clear what types of experimental data are needed or how closely the CFD input values and experimental conditions should be matched (similar or identical airway geometries, entrance airflow, or aerosol profiles) to validate CFD derived predictions. Due to the complexity of CFD computer codes and the multiplicity of deposition mechanisms, it is possible that total aerosol deposition may be accurately predicted and the resulting local particle deposition patterns are incorrect, or vice versa. Specific examples and suggestions for several challenges to experimentalists and modelers are presented.

  8. Aerosol characteristics and sources for the Amazon basin during the wet season

    SciTech Connect

    Artaxo, P. ); Maenhaut, W. ); Storms, H.; Van Grieken, R. )

    1990-09-20

    Fine (< 2.0 {mu}m) and coarse (2.0 - 15 {mu}m) aerosol fractions were collected using stacked filter units, at three sites under the forest canopy and at three levels of a tower inside the jungle. Particle-induced x-ray emission (PIXE) was used to measure concentrations Na, Mg, Al, Si, P, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Br, Rb, Sr, Zr, and Pb. Morphological and trace element measurements of individual particles were carried out by automated electron probe x-ray microanalysis. Gravimetric analysis was performed to obtain the fine and coarse aerosol mass concentration. The concentrations of soil dust related elements (Al, Si, Ti, Fe, Mn) were 5 times larger in the wet season compared to the 1985 ABLE 2A dry season experiment. Biogenic aerosol related elements in the fine fraction showed lower concentrations in the wet season. Fine aerosol mass concentration averaged only 2.1 {plus minus} 0.7 {mu}g m{sup {minus}3}, while the average coarse mass concentration was 6.1 {plus minus} 1.8 {mu}g m{sup {minus}3}. Sulfur concentrations averaged 76 {plus minus} 14 ng m{sup {minus}3} in the fine fraction and 37 {plus minus} 9 ng m{sup {minus}3} in the coarse fraction. Only two factors explained about 90% of the data variability for the fine and coarse aerosol fractions. These were soil dust (represented mainly by Al, Si, Ti, Mn, and Fe) and biogenic aerosol (represented by K, P, Cl, S, Zn, and the aerosol mass concentration). Biogenic particles account for 55-95% of the airborne concentrations and consisted of leaf fragments, pollen grains, fungi, algae, and other types of particles. It is possible that biogenic particles can play an important role in the global aerosol budget and in the global biogeochemical cycles of various elements.

  9. The role of anisotropic expansion for pulmonary acinar aerosol deposition

    PubMed Central

    Hofemeier, Philipp; Sznitman, Josué

    2016-01-01

    Lung deformations at the local pulmonary acinar scale are intrinsically anisotropic. Despite progress in imaging modalities, the true heterogeneous nature of acinar expansion during breathing remains controversial, where our understanding of inhaled aerosol deposition still widely emanates from studies under self-similar, isotropic wall motions. Building on recent 3D models of multi-generation acinar networks, we explore in numerical simulations how different hypothesized scenarios of anisotropic expansion influence deposition outcomes of inhaled aerosols in the acinar depths. While the broader range of particles acknowledged to reach the acinar region (dp = 0.005–5.0 μm) are largely unaffected by the details of anisotropic expansion under tidal breathing, our results suggest nevertheless that anisotropy modulates the deposition sites and fractions for a narrow band of sub-micron particles (dp ~ 0.5–0.75 μm), where the fate of aerosols is greatly intertwined with local convective flows. Our findings underscore how intrinsic aerosol motion (i.e. diffusion, sedimentation) undermines the role of anisotropic wall expansion that is often attributed in determining aerosol mixing and acinar deposition. PMID:27614613

  10. Analyses of wet and bulk deposition in four different regions of Istanbul, Turkey

    NASA Astrophysics Data System (ADS)

    Akkoyunlu, Bülent O.; Tayanç, Mete

    This study presents the chemical composition of wet deposition that was collected at four different regions of İstanbul, Topkapi, Bağcilar, Maltepe and Göztepe, during the period January 2001-May 2001. Bulk deposition was collected together with the wet deposition at only one station, Göztepe, during the period of January 2001-December 2001. Fifty four wet deposition samples and 21 bulk samples were collected during the study period. The mean value of pH of wet deposition samples for all regions was found to be 5.26. Results indicate that Ca 2+ concentration in precipitation was high, as was SO 42-, neutralizing the acidity. The mean value of the non-sea-salt fraction in the wet deposition for Ca 2+ and SO 42- were 98%, 91% indicating that Ca 2+ and SO 42- were mainly coming from sources other than sea. Difference between bulk and wet deposition of Ca 2+ and SO 42- was found to be highest. Those differences between bulk and wet samples with respect to the overall concentration (wet+bulk) were lower than 30% for ammonium and nitrate, while the differences of SO 42-, Ca 2+, Mg 2+, Cl -, Na + vary between 62% and 36%. Higher enrichment factors were found for most ions and higher correlation coefficients were obtained among most of the ions in dry and bulk deposition, in comparison with wet deposition.

  11. A key process controlling the wet removal of aerosols: new observational evidence

    NASA Astrophysics Data System (ADS)

    Ohata, Sho; Moteki, Nobuhiro; Mori, Tatsuhiro; Koike, Makoto; Kondo, Yutaka

    2016-10-01

    The lifetime and spatial distributions of accumulation-mode aerosols in a size range of approximately 0.05–1 μm, and thus their global and regional climate impacts, are primarily constrained by their removal via cloud and precipitation (wet removal). However, the microphysical process that predominantly controls the removal efficiency remains unidentified because of observational difficulties. Here, we demonstrate that the activation of aerosols to cloud droplets (nucleation scavenging) predominantly controls the wet removal efficiency of accumulation-mode aerosols, using water-insoluble black carbon as an observable particle tracer during the removal process. From simultaneous ground-based observations of black carbon in air (prior to removal) and in rainwater (after removal) in Tokyo, Japan, we found that the wet removal efficiency depends strongly on particle size, and the size dependence can be explained quantitatively by the observed size-dependent cloud-nucleating ability. Furthermore, our observational method provides an estimate of the effective supersaturation of water vapour in precipitating cloud clusters, a key parameter controlling nucleation scavenging. These novel data firmly indicate the importance of quantitative numerical simulations of the nucleation scavenging process to improve the model’s ability to predict the atmospheric aerosol burden and the resultant climate forcings, and enable a new validation of such simulations.

  12. A key process controlling the wet removal of aerosols: new observational evidence

    PubMed Central

    Ohata, Sho; Moteki, Nobuhiro; Mori, Tatsuhiro; Koike, Makoto; Kondo, Yutaka

    2016-01-01

    The lifetime and spatial distributions of accumulation-mode aerosols in a size range of approximately 0.05–1 μm, and thus their global and regional climate impacts, are primarily constrained by their removal via cloud and precipitation (wet removal). However, the microphysical process that predominantly controls the removal efficiency remains unidentified because of observational difficulties. Here, we demonstrate that the activation of aerosols to cloud droplets (nucleation scavenging) predominantly controls the wet removal efficiency of accumulation-mode aerosols, using water-insoluble black carbon as an observable particle tracer during the removal process. From simultaneous ground-based observations of black carbon in air (prior to removal) and in rainwater (after removal) in Tokyo, Japan, we found that the wet removal efficiency depends strongly on particle size, and the size dependence can be explained quantitatively by the observed size-dependent cloud-nucleating ability. Furthermore, our observational method provides an estimate of the effective supersaturation of water vapour in precipitating cloud clusters, a key parameter controlling nucleation scavenging. These novel data firmly indicate the importance of quantitative numerical simulations of the nucleation scavenging process to improve the model’s ability to predict the atmospheric aerosol burden and the resultant climate forcings, and enable a new validation of such simulations. PMID:27703169

  13. FACTORS AFFECTING THE DEPOSITION OF AEROSOLIZED INSULIN

    EPA Science Inventory

    Abstract
    Background
    The inhalation of insulin for absorption into the bloodstream via the lung seems to be a promising technique for the treatment of diabetes mellitus. A fundamental issue to be resolved in the development of such insulin aerosol delivery systems is their...

  14. Wet deposition monitoring and modelling in New Brunswick — An area dominated by wet deposition due to long-range transport

    NASA Astrophysics Data System (ADS)

    Davis, Claude S.

    Two wet deposition monitoring networks, the Coleson Cove Precipitation Monitoring Network (CCPMN) (12 stations) located in the Coleson Cove-Saint John area of south New Brunswick, and the Expanded New Brunswick Precipitation Monitoring Network (ENBPMN) (6 stations) covering the remainder of the province, were established in May 1988. The monitoring networks and a complementary modelling study were implemented to assess the relative contributions of local and distant sources to wet deposition in New Brunswick. Quality assurance/quality control activities for the networks included independent external audits, collocated samplers at one site and comparisons of weekly measurements at the ENBPMN sampler and the Canadian Air and Precipitation Monitoring Network (CAPMoN) sampler which makes daily measurements. The intercomparisons provided reassurance that the networks provided high quality data. Analysis of 2 years (June 1988-May 1990) data from the networks included routine statistical analyses for acid rain chemistry as well as analysis of 1 year of daily back trajectory data from Harcourt, New Brunswick. Three-day back trajectories determined at 12-h intervals from Harcourt on days with precipitatio showed that air masses originate mainly from regions in Quebec, Ontario and northeast U.S.A. which are known to have high sulphur oxide emissions. Some 18 trajectories were associated with 50% of the wet sulphate deposition and over 200 trajectories with 75% of the deposition in the 1-year period ending 31 May 1989. The MESOPUFF model, applied to an 800 km by 800 km domain that included the entire province of New Brunswick, was used to make predictions of wet sulphate and nitrate deposition at each of the wet deposition monitoring stations for a 2-year period, 1 June 1988-31 May 1990. Model predictions averaged over all receptors due to all sources in the model domain accounted for 7-25% of the measured seasonal average wet sulphate deposition and less than 3% of the

  15. Changes in wet nitrogen deposition in the United States between 1985 and 2012

    NASA Astrophysics Data System (ADS)

    Du, Enzai; de Vries, Wim; Galloway, James N.; Hu, Xueyang; Fang, Jingyun

    2014-09-01

    The United States (US) is among the global hotspots of nitrogen (N) deposition and assessing the temporal trends of wet N deposition is relevant to quantify the effectiveness of existing N regulation policies and its consequent environmental effects. This study analyzed changes in observed wet deposition of dissolved inorganic N (DIN = ammonium + nitrate) in the US between 1985 and 2012 by applying a Mann-Kendall test and Regional Kendall test. Current wet DIN deposition (2011-2012) data were used to gain insight in the current pattern of N deposition. Wet DIN deposition generally decreased going from Midwest > Northeast > South > West region with a national mean rate of 3.5 kg N ha-1 yr-1. Ammonium dominated wet DIN deposition in the Midwest, South and West regions, whereas nitrate and ammonium both contributed a half in the Northeast region. Wet DIN deposition showed no significant change at the national scale between 1985 and 2012, but profound changes occurred in its components. Wet ammonium deposition showed a significant increasing trend at national scale (0.013 kg N ha-1 yr-2), with the highest increase in the Midwest and eastern part of the South region. Inversely, wet nitrate deposition decreased significantly at national scale (-0.014 kg N ha-1 yr-2), with the largest reduction in the Northeast region. Overall, ratios of ammonium versus nitrate in wet deposition showed a significant increase in all the four regions, resulting in a transition of the dominant N species from nitrate to ammonium. Distinct magnitudes, trends and patterns of wet ammonium and nitrate deposition suggest the needs to control N emissions by species and regions to avoid negative effects of N deposition on ecosystem health and function in the US.

  16. A source of experimental underestimation of aerosol bolus deposition

    NASA Technical Reports Server (NTRS)

    Verbanck, S.; Darquenne, C.; Prisk, G. K.; Vincken, W.; Paiva, M.

    1999-01-01

    We examined the measurement error in inhaled and exhaled aerosol concentration resulting from the bolus delivery system when small volumes of monodisperse aerosols are inspired to different lung depths. A laser photometer that illuminated approximately 75% of the breathing path cross section recorded low inhaled bolus half-widths (42 ml) and negative deposition values for shallow bolus inhalation when the inhalation path of a 60-ml aerosol was straight and unobstructed. We attributed these results to incomplete mixing of the inhaled aerosol bolus over the breathing path cross section, on the basis of simultaneous recordings of the photometer with a particle-counter sampling from either the center or the edge of the breathing path. Inserting a 90 degrees bend into the inhaled bolus path increased the photometer measurement of inhaled bolus half-width to 57 ml and yielded positive deposition values. Dispersion, which is predominantly affected by exhaled bolus half-width, was not significantly altered by the 90 degrees bend. We conclude that aerosol bolus-delivery systems should ensure adequate mixing of the inhaled bolus to avoid error in measurement of bolus deposition.

  17. Aerosol deposition and losses in two alpha air monitors

    SciTech Connect

    Biermann, A.H.; Sawyer, S.R.

    1985-11-27

    We assessed particle deposition and loss occurring in two alpha-air monitors: an Eberline Alpha-3 Continuous Air Monitor (CAM) and a working-area transuranic aerosol monitor (WOTAMS). We investigated the dependence of particle size on losses in the sampling inlets and the real-time alpha detector areas for both instruments. We determined the uniformity of particle deposition on the filter to ascertain the effectiveness of the detector and collection-filter configuration. Results indicate that particle losses are a strong function of particle size in the CAM unit, with a 44% loss occurring for 6-..mu..m-diameter aerosols and a 0.3% loss for 0.6-..mu..m-diameter aerosols. Losses in the WOTAMS were less than 1% for particle diameters in the 0.6-to-7 ..mu..m range.

  18. Modeling wet deposition and concentration of inorganics over Northeast Asia with MRI-PM/c

    NASA Astrophysics Data System (ADS)

    Kajino, M.; Deushi, M.; Maki, T.; Oshima, N.; Inomata, Y.; Sato, K.; Ohizumi, T.; Ueda, H.

    2012-11-01

    We conducted a regional-scale simulation over Northeast Asia for the year 2006 using an aerosol chemical transport model, with time-varying lateral and upper boundary concentrations of gaseous species predicted by a global stratospheric and tropospheric chemistry-climate model. The present one-way nested global-through-regional-scale model is named the Meteorological Research Institute-Passive-tracers Model system for atmospheric Chemistry (MRI-PM/c). We evaluated the model's performance with respect to the major anthropogenic and natural inorganic components, SO42-, NH4+, NO3-, Na+ and Ca2+ in the air, rain and snow measured at the Acid Deposition Monitoring Network in East Asia (EANET) stations. Statistical analysis showed that approximately 40-50 % and 70-80 % of simulated concentration and wet deposition of SO42-, NH4+, NO3-and Ca2+ are within factors of 2 and 5 of the observations, respectively. The prediction of the sea-salt originated component Na+ was not successful at near-coastal stations (where the distance from the coast ranged from 150 to 700 m), because the model grid resolution (Δx=60 km) is too coarse to resolve it. The simulated Na+ in precipitation was significantly underestimated by up to a factor of 30.

  19. Surfactant Driven Post-Deposition Spreading of Aerosols on Complex Aqueous Subphases. 2: Low Deposition Flux Representative of Aerosol Delivery to Small Airways

    PubMed Central

    Sharma, Ramankur; Khanal, Amsul; Corcoran, Timothy E.; Przybycien, Todd M.; Tilton, Robert D.

    2015-01-01

    Abstract Background: Cystic fibrosis (CF) is associated with the accumulation of dehydrated mucus in the pulmonary airways. This alters ventilation and aerosol deposition patterns in ways that limit drug delivery to peripheral lung regions. We investigated the use of surfactant-based, self-dispersing aerosol carriers that produce surface tension gradients to drive two-dimensional transport of aerosolized medications via Marangoni flows after deposition on the airway surface liquid (ASL). We considered the post-deposition spreading of individual aerosol droplets and two-dimensional expansion of a field of aerosol droplets, when deposited at low fluxes that are representative of aerosol deposition in the small airways. Methods: We used physically entangled aqueous solutions of poly(acrylamide) or porcine gastric mucin as simple ASL mimics that adequately capture the full miscibility but slow penetration of entangled macromolecular chains of the ASL into the deposited drop. Surfactant formulations were prepared with aqueous solutions of nonionic tyloxapol or FS-3100 fluorosurfactant. Fluorescein dye served as a model “drug” tracer and to visualize the extent of post-deposition spreading. Results: The surfactants not only enhanced post-deposition spreading of individual aerosol droplets due to localized Marangoni stresses, as previously observed with macroscopic drops, but they also produced large-scale Marangoni stresses that caused the deposited aerosol fields to expand into initially unexposed regions of the subphase. We show that the latter is the main mechanism for spreading drug over large distances when aerosol is deposited at low fluxes representative of the small airways. The large scale convective expansion of the aerosol field drives the tracer (drug mimic) over areas that would cover an entire airway generation or more, in peripheral airways, where sub-monolayer droplet deposition is expected during aerosol inhalation. Conclusions: The results suggest

  20. Computational fluid dynamics analysis of aerosol deposition in pebble beds

    NASA Astrophysics Data System (ADS)

    Mkhosi, Margaret Msongi

    2007-12-01

    The Pebble Bed Modular Reactor is a high temperature gas cooled reactor which uses helium gas as a coolant. The reactor uses spherical graphite pebbles as fuel. The fuel design is inherently resistant to the release of the radioactive material up to high temperatures; therefore, the plant can withstand a broad spectrum of accidents with limited release of radionuclides to the environment. Despite safety features of the concepts, these reactors still contain large inventories of radioactive materials. The transport of most of the radioactive materials in an accident occurs in the form of aerosol particles. In this dissertation, the limits of applicability of existing computational fluid dynamics code FLUENT to the prediction of aerosol transport have been explored. The code was run using the Reynolds Averaged Navier-Stokes turbulence models to determine the effects of different turbulence models on the prediction of aerosol particle deposition. Analyses were performed for up to three unit cells in the orthorhombic configuration. For low flow conditions representing natural circulation driven flow, the laminar flow model was used and the results were compared with existing experimental data for packed beds. The results compares well with experimental data in the low flow regime. For conditions corresponding to normal operating of the reactor, analyses were performed using the standard k-ɛ turbulence model. From the inertial deposition results, a correlation that can be used to estimate the deposition of aerosol particles within pebble beds given inlet flow conditions has been developed. These results were converted into a dimensionless form as a function of a modified Stokes number. Based on results obtained in the laminar regime and for individual pebbles, the correlation developed for the inertial impaction component of deposition is believed to be credible. The form of the correlation developed also allows these results to be applied to pebble beds of different

  1. Aerosol chemical vapor deposition of metal oxide films

    DOEpatents

    Ott, Kevin C.; Kodas, Toivo T.

    1994-01-01

    A process of preparing a film of a multicomponent metal oxide including: forming an aerosol from a solution comprised of a suitable solvent and at least two precursor compounds capable of volatilizing at temperatures lower than the decomposition temperature of said precursor compounds; passing said aerosol in combination with a suitable oxygen-containing carrier gas into a heated zone, said heated zone having a temperature sufficient to evaporate the solvent and volatilize said precursor compounds; and passing said volatilized precursor compounds against the surface of a substrate, said substrate having a sufficient temperature to decompose said volatilized precursor compounds whereby metal atoms contained within said volatilized precursor compounds are deposited as a metal oxide film upon the substrate is disclosed. In addition, a coated article comprising a multicomponent metal oxide film conforming to the surface of a substrate selected from the group consisting of silicon, magnesium oxide, yttrium-stabilized zirconium oxide, sapphire, or lanthanum gallate, said multicomponent metal oxide film characterized as having a substantially uniform thickness upon said FIELD OF THE INVENTION The present invention relates to the field of film coating deposition techniques, and more particularly to the deposition of multicomponent metal oxide films by aerosol chemical vapor deposition. This invention is the result of a contract with the Department of Energy (Contract No. W-7405-ENG-36).

  2. Quantitative deposition of aerosolized gentamicin in cystic fibrosis

    SciTech Connect

    Ilowite, J.S.; Gorvoy, J.D.; Smaldone, G.C.

    1987-12-01

    In cystic fibrosis (CF), the clinical effectiveness of aerosolized antibiotics is controversial. Previous investigators have not considered the type of nebulizer, droplet size, and dose to the lung in assessing the results of aerosol therapy. The present study tests the importance of these factors by standardizing an aerosol system for delivery of antibiotics and other agents to patients with CF. Particle size, distribution, and output from a commercially available nebulizer were measured. Thirteen patients with CF inhaled aerosol (MMAD = 1.1 micron) containing gentamicin (160 mg in nebulizer) and /sup 99m/Tc-labeled human serum albumin. Patients' sputum and serum were analyzed for gentamicin levels by immunoenzymatic assay. Using a gamma camera and suitable filters, central versus peripheral deposition (C/P ratio) and whole lung deposition were measured and related to sputum gentamicin levels. Gentamicin deposit averaged 12.3 mg +/- 5.9 (SD) or 7.69% of the original amount placed in the nebulizer. Peak sputum levels averaged 376.6 micrograms/ml +/- 275, whereas serum levels were undetectable in all patients. When peak sputum levels were normalized for the amount deposited, a close correlation with C/P ratio was obtained (r = 0.88, p less than 0.05). Furthermore, an inverse relationship was found between the C/P ratio and the %FEV1 (r = 0.76, p less than 0.05). Finally, a bell-shaped relationship between deposited dose and minute ventilation was seen in the patients (r = 0.88, p less than 0.05), i.e., an optimal minute ventilation was shown. These relationships may be important when designing future clinical studies.

  3. Thermally induced superhydrophilicity in TiO2 films prepared by supersonic aerosol deposition.

    PubMed

    Park, Jung-Jae; Kim, Do-Yeon; Latthe, Sanjay S; Lee, Jong-Gun; Swihart, Mark T; Yoon, Sam S

    2013-07-10

    Superhydrophilic and superhydrophobic surfaces enable self-cleaning phenomena, either forming a continuous water film or forming droplets that roll off the surface, respectively. TiO2 films are well-known for their extreme hydrophilicity and photocatalytic characteristics. Here, we describe nanostructured TiO2 thin films prepared by supersonic aerosol deposition, including a thorough study of the effects of the annealing temperature on the crystal structure, surface morphology, surface roughness, and wetting properties. Powder X-ray diffraction showed that supersonic deposition resulted in fragmentation and amorphization of the micrometer-size anatase (60%)-rutile (40%) precursor powder and that, upon annealing, a substantial fraction of the film (~30%) crystallized in the highly hydrophilic but metastable brookite phase. The film morphology was also somewhat modified after annealing. Scanning electron microscopy and atomic force microscopy revealed rough granular films with high surface roughness. The as-deposited TiO2 films were moderately hydrophilic with a water contact angle (θ) of ~45°, whereas TiO2 films annealed at 500 °C became superhydrophilic (θ ~ 0°) without UV illumination. This thermally induced superhydrophilicity of the TiO2 films can be explained on the basis of the combined effects of the change in the crystal structure, surface microstructure, and surface roughness. Supersonic aerosol deposition followed by annealing is uniquely able to produce these nanostructured films containing a mixture of all three TiO2 phases (anatase, rutile, and brookite) and exhibiting superhydrophilicity without UV illumination.

  4. Atmospheric wet deposition of sulfur and nitrogen in Jiuzhaigou National Nature Reserve, Sichuan Province, China.

    PubMed

    Qiao, Xue; Xiao, Weiyang; Jaffe, Daniel; Kota, Sri Harsha; Ying, Qi; Tang, Ya

    2015-04-01

    In the last two decades, remarkable ecological changes have been observed in Jiuzhaigou National Nature Reserve (JNNR). Some of these changes might be related to excessive deposition of sulfur (S) and nitrogen (N), but the relationship has not been quantified due to lack of monitoring data, particularly S and N deposition data. In this study, we investigated the concentrations, fluxes, and sources of S and N wet deposition in JNNR from April 2010 to May 2011. The results show that SO4(2-), NO3-, and NH4+ concentrations in the wet deposition were 39.4-170.5, 6.2-34.8, and 0.2-61.2 μeq L(-1), with annual Volume-Weighted Mean (VWM) concentrations of 70.5, 12.7, and 13.4 μeq L(-1), respectively. Annual wet deposition fluxes of SO4(2-), NO3-, and NH4+ were 8.06, 1.29, and 1.39 kg S(N)ha(-1), respectively, accounting for about 90% of annual atmospheric inputs of these species at the monitoring site. The results of Positive Matrix Factorization (PMF) analysis show that fossil fuel combustion, agriculture, and aged sea salt contributed to 99% and 83% of annual wet deposition fluxes of SO4(2-) and NO3-, respectively. Agriculture alone contributed to 89% of annual wet deposition flux of NH4+. Although wet deposition in JNNR was polluted by anthropogenic acids, the acidity was largely neutralized by the Ca2+ from crust and 81% of wet deposition samples had a pH higher than 6.00. However, acid rain mainly caused by SO4(2-) continued to occur in the wet season, when ambient alkaline dust concentration was lower. Since anthropogenic emissions have elevated S and N deposition and caused acid rain in JNNR, further studies are needed to better quantify the regional sources and ecological effects of S and N deposition for JNNR.

  5. 3D modelling of transport, deposition and resuspension of highway deposited sediments in wet detention ponds.

    PubMed

    Bentzen, T R

    2010-01-01

    The paper presents results from an experimental and numerical study of flows and transport of primarily particle bound pollutants in highway wet detention ponds. The study presented here is part of a general investigation on road runoff and pollution in respect to wet detention ponds. The objective is to evaluate the quality of long term simulation based on historical rains series of the pollutant discharges from roads and highways. A three-dimensional hydrodynamic and mud transport model is used for the investigation. The transport model has been calibrated and validated on e.g. experiments in a 30 m long concrete channel with width of 0.8 m and a water depth of approximately 0.8 m and in circular flume experiments in order to reproduce near-bed specific processes such as resuspension and consolidation. With a fairly good agreement with measurements, modelling of hydrodynamics, transport of dissolved pollutants and particles in wet detention ponds is possible with application of a three dimensional RANS model and the advection/dispersion equation taken physical phenomena like wind, waves, deposition, erosion and consolidation of the bottom sediment into account.

  6. Assessing the emission sources of atmospheric mercury in wet deposition across Illinois.

    PubMed

    Gratz, Lynne E; Keeler, Gerald J; Morishita, Masako; Barres, James A; Dvonch, J Timothy

    2013-03-15

    From August 4, 2007 to August 31, 2009, we collected event-based precipitation samples for mercury (Hg) and trace element analyses at four sites in Illinois (IL), USA. The objectives of these measurements were to quantify Hg wet deposition across the state, and to assess the contributions to Hg in precipitation from major local and regional emission sources. Monitoring sites were located, from north to south, in Chicago, Peoria, Nilwood, and Carbondale, IL. Measurements from these four sites demonstrated that a clear spatial gradient in Hg wet deposition was not evident across the state. Each site received>10μgm(-2) of Hg wet deposition annually, and these observed values were comparable to annual Hg wet deposition measurements from other event-based precipitation monitoring sites in source-impacted areas of the Midwestern U.S. We applied the multivariate statistical receptor model, Positive Matrix Factorization (EPA PMF v3.0), to the measured Hg and trace element wet deposition amounts at the four sites. Results suggested that 50% to 74% of total Hg wet deposition at each site could be attributed to coal combustion emissions. The other source signatures identified in the precipitation compositions included cement manufacturing, mixed metal smelting/waste incineration, iron-steel production, and a phosphorus source. We also applied a hybrid receptor model, Quantitative Transport Bias Analysis (QTBA), to the Hg wet deposition datasets to identify the major source regions associated with the measured values. The calculated QTBA probability fields suggested that transport from urban/industrial areas, such as Chicago/Gary, St. Louis, and the Ohio River Valley, resulted in some of the highest estimated event-based Hg wet deposition amounts at the four sites (potential mass transfer of up to 0.32μgm(-2)). The combined application of PMF and QTBA supported the hypothesis that local and regional coal combustion was the largest source of Hg wet deposition in Illinois.

  7. Ozone and aerosol distributions over the Amazon Basin during the wet season

    NASA Technical Reports Server (NTRS)

    Browell, Edward V.; Gregory, G. L.; Harriss, R. C.; Kirchhoff, V. W. J. H.

    1990-01-01

    Results are presented of O3 and aerosol measurements made in the lower troposphere from April 13 through May 10, 1987, as part of the wet season field experiment. Aircraft flights on the NASA Electra were conducted in the vicinity of Manaus, Brazil and between Manaus and the mouth of the Amazon River. Airborne O3 measurements were made in situ and with a lidar system pointed below the aircraft in nadir mode of operation. Data collection and results concerning the distributions of O3 and aerosols observed during the wet season from within the mixed layer to the middle troposphere over the central Amazon basin and between Manaus and Belem are discussed, and these observations are compared to the measurements obtained in the 1985 dry season. Ozone mixing ratio values are found to be lower than those of the 1985 dry season by 6-8 ppbv, indicating a strong removal process near the surface during wet season. It is also found that within the mixed layer O3 levels appeared to be lower over the forest compared to over the ocean.

  8. Wet deposition at the base of Mt Everest: Seasonal evolution of the chemistry and isotopic composition

    NASA Astrophysics Data System (ADS)

    Balestrini, Raffaella; Delconte, Carlo A.; Sacchi, Elisa; Wilson, Alana M.; Williams, Mark W.; Cristofanelli, Paolo; Putero, Davide

    2016-12-01

    The chemistry of wet deposition was investigated during 2012-2014 at the Pyramid International Laboratory in the Upper Khumbu Valley, Nepal, at 5050 m a.s.l., within the Global Atmosphere Watch (GAW) programme. The main hydro-chemical species and stable isotopes of the water molecule were determined for monsoon rain (July-September) and snow samples (October-June). To evaluate the synoptic-scale variability of air masses reaching the measurement site, 5 day back-trajectories were computed for the sampling period. Ion concentrations in precipitation during the monsoon were low suggesting that they represent global regional background concentrations. The associations between ions suggested that the principal sources of chemical species were marine aerosols, rock and soil dust, and fossil fuel combustion. Most chemical species exhibited a pattern during the monsoon, with maxima at the beginning and at the end of the season, partially correlated with the precipitation amount. Snow samples exhibited significantly higher concentrations of chemical species, compared to the monsoon rainfall observations. Particularly during 2013, elevated concentrations of NO3-, SO42- and NH4+ were measured in the first winter snow event, and in May at the end of the pre-monsoon season. The analysis of large-scale circulation and wind regimes as well as atmospheric composition observations in the region indicates the transport of polluted air masses from the Himalayan foothills and Indian sub-continent up to the Himalaya region. During the summer monsoon onset period, the greater values of pollutants can be attributed to air-mass transport from the planetary boundary layer (PBL) of the Indo-Gangetic plains. Isotopic data confirm that during the monsoon period, precipitation occurred from water vapor that originated from the Indian Ocean and the Bay of Bengal; by contrast during the non-monsoon period, an isotopic signature of more continental origin appeared, indicating that the higher

  9. A possible deficiency in estimates of wet deposition obtained from data generated by the NADP/NTN network

    USGS Publications Warehouse

    Claassen, H.C.; Halm, D.R.

    1995-01-01

    A conventional precipitation scavenging model is used to evaluate the effect of the performance of a wet-deposition collector on the reported deposition amounts. Three National Atmospheric Deposition Program/National Trends Network sites in semi arid western Colorado were chosen to evaluate chloride and sulfate wet deposition. Observations of the performance of a wet-deposition collector have demonstrated a delay in opening and cycling during a precipitation event. A significant fraction of wet deposition may be excluded when small amounts of initial precipitation are not sampled and a potentially large fraction of annual wet deposition may be excluded if a majority of precipitation events are small. The actual amount missed depends on the precipitation intensity, variability of intensity with time, raindrop or snowflake size and the individual performance characteristics of the collector. Detailed performance data are needed for individual wet-deposition collectors before accurate estimates of wet deposition can be expected.

  10. AN EXAMINATION OF THE CMAQ SIMULATIONS OF THE WET DEPOSITION OF AMMONIUM FROM A BAYESIAN PERSPECTIVE

    EPA Science Inventory

    The objective of this study is to ascertain the effects of precipitation simulations and emissions on CMAQ simulations of deposition. In both seasons, CMAQ tends to underpredict the deposition amounts. Based on the co-located measurements of ammonium wet deposition and precipita...

  11. Effects of wet deposition on the abundance and size distribution of black carbon in East Asia

    NASA Astrophysics Data System (ADS)

    Kondo, Y.; Moteki, N.; Oshima, N.; Ohata, S.; Koike, M.; Shibano, Y.; Takegawa, N.; Kita, K.

    2016-05-01

    An improved understanding of the variations in the mass concentration and size distribution of black carbon (BC) in the free troposphere (FT) over East Asia, where BC emissions are very high, is needed to reliably estimate the radiative forcing of BC in climate models. We measured these parameters and the carbon monoxide (CO) concentration by conducting the Aerosol Radiative Forcing in East Asia (A-FORCE) 2013W aircraft campaign in East Asia in winter 2013 and compared these data with measurements made in the same region in spring 2009. The median BC concentrations in the FT originating from North China (NC) and South China (SC) showed different seasonal variations, which were primarily caused by variations in meteorological conditions. CO concentrations above the background were much higher in SC than in NC in both seasons, suggesting a more active upward transport of CO. In SC, precipitation greatly increased from winter to spring, leading to an increased wet deposition of BC. As a result, the median BC concentration in the FT was highest in SC air in winter. This season and region were optimal for the effective transport of BC from the planetary boundary layer to the FT. The count median diameters of the BC size distributions generally decreased with altitude via wet removal during upward transport. The altitude dependence of the BC size distributions was similar in winter and spring, in accord with the similarity in the BC mixing state. The observed BC concentrations and microphysical properties will be useful for evaluating the performance of climate models.

  12. Aerosol profiling with lidar in the Amazon Basin during the wet and dry season

    NASA Astrophysics Data System (ADS)

    Baars, H.; Ansmann, A.; Althausen, D.; Engelmann, R.; Heese, B.; Müller, D.; Artaxo, P.; Paixao, M.; Pauliquevis, T.; Souza, R.

    2012-11-01

    For the first time, multiwavelength polarization Raman lidar observations of optical and microphysical particle properties over the Amazon Basin are presented. The fully automated advanced Raman lidar was deployed 60 km north of Manaus, Brazil (2.5°S, 60°W) in the Amazon rain forest from January to November 2008. The measurements thus cover both the wet season (Dec-June) and the dry or burning season (July-Nov). Two cases studies of young and aged smoke plumes are discussed in terms of spectrally resolved optical properties (355, 532, and 1064 nm) and further lidar products such as particle effective radius and single-scattering albedo. These measurement examples confirm that biomass burning aerosols show a broad spectrum of optical, microphysical, and chemical properties. The statistical analysis of the entire measurement period revealed strong differences between the pristine wet and the polluted dry season. African smoke and dust advection frequently interrupt the pristine phases during the wet season. Compared to pristine wet season conditions, the particle scattering coefficients in the lowermost 2 km of the atmosphere were found to be enhanced, on average, by a factor of 4 during periods of African aerosol intrusion and by a factor of 6 during the dry (burning) season. Under pristine conditions, the particle extinction coefficients and optical depth for 532 nm wavelength were frequently as low as 10-30 Mm-1 and <0.05, respectively. During the dry season, biomass burning smoke plumes reached to 3-5 km height and caused a mean optical depth at 532 nm of 0.26. On average during that season, particle extinction coefficients (532 nm) were of the order of 100 Mm-1 in the main pollution layer (up to 2 km height). Ångström exponents were mainly between 1.0 and 1.5, and the majority of the observed lidar ratios were between 50-80 sr.

  13. Investigation of Mercury Wet Deposition Physicochemistry in the Ohio River Valley through Automated Sequential Sampling

    EPA Science Inventory

    Intra-storm variability and soluble fractionation was explored for summer-time rain events in Steubenville, Ohio to evaluate the physical processes controlling mercury (Hg) in wet deposition in this industrialized region. Comprehensive precipitation sample collection was conducte...

  14. Traffic aerosol lobar doses deposited in the human respiratory system.

    PubMed

    Manigrasso, Maurizio; Vernale, Claudio; Avino, Pasquale

    2015-10-30

    Aerosol pollution in urban environments has been recognized to be responsible for important pathologies of the cardiovascular and respiratory systems. In this perspective, great attention has been addressed to Ultra Fine Particles (UFPs < 100 nm), because they efficiently penetrate into the respiratory system and are capable of translocating from the airways into the blood circulation. This paper describes the aerosol regional doses deposited in the human respiratory system in a high-traffic urban area. The aerosol measurements were carried out on a curbside in downtown Rome, on a street characterized by a high density of autovehicular traffic. Aerosol number-size distributions were measured by means of a Fast Mobility Particle Sizer in the range from 5.6 to 560 nm with a 1 s time resolution. Dosimetry estimates were performed with the Multiple-Path Particle Dosimetry model by means of the stochastic lung model. The exposure scenario close to traffic is represented by a sequence of short-term peak exposures: about 6.6 × 10(10) particles are deposited hourly into the respiratory system. After 1 h of exposure in proximity of traffic, 1.29 × 10(10), 1.88 × 10(10), and 3.45 × 10(10) particles are deposited in the head, tracheobronchial, and alveolar regions. More than 95 % of such doses are represented by UFPs. Finally, according to the greater dose estimated, the right lung lobes are expected to be more susceptible to respiratory pathologies than the left lobes.

  15. Deposition of biological aerosols on HVAC heat exchangers

    SciTech Connect

    Siegel, Jeffrey; Walker, Ian

    2001-09-01

    Many biologically active materials are transported as bioaerosols 1-10 {micro}m in diameter. These particles can deposit on cooling and heating coils and lead to serious indoor air quality problems. This paper investigates several of the mechanisms that lead to aerosol deposition on fin and tube heat exchangers. A model has been developed that incorporates the effects of several deposition mechanisms, including impaction, Brownian and turbulent diffusion, turbophoresis, thermophoresis, diffusiophoresis, and gravitational settling. The model is applied to a typical range of air velocities that are found in commercial and residential HVAC systems 1 - 6 m/s (200 - 1200 ft/min), particle diameters from 1 - 8 {micro}m, and fin spacings from 3.2 - 7.9 fins/cm (8 - 16 fins/inch or FPI). The results from the model are compared to results from an experimental apparatus that directly measures deposition on a 4.7 fins/cm (12 FPI) coil. The model agrees reasonably well with this measured data and suggests that cooling coils are an important sink for biological aerosols and consequently a potential source of indoor air quality problems.

  16. Mercury speciation in wet deposition samples collected from a coastal area of Minamata Bay

    NASA Astrophysics Data System (ADS)

    Marumoto, Kohji; Matsuyama, Akito

    2014-04-01

    To better understand the methylation and demethylation of mercury (Hg) in the atmosphere, monomethyl mercury (MMHg) concentrations in wet deposition samples collected in the Minamata Bay area from September, 2009 to August, 2010 were determined. The concentrations of total Hg (dissolved Hg + particulate Hg) and dissolved reactive Hg were also measured. The volume-weighted mean concentrations of dissolved MMHg and total Hg were 0.061 and 5.9 ng L-1, respectively. Almost 90% of total Hg was in the dissolved phase and dissolved reactive Hg was the dominant Hg species in the wet deposition. The wet deposition fluxes of total Hg and reactive Hg increased in the rainy season (summer and fall), while the concentrations and wet deposition fluxes of MMHg were higher in winter and spring than in summer. Factors affecting this seasonal variation of MMHg were also considered. The MMHg in wet depositions may be decomposed by the increased levels of UV radiation in summer months, although MMHg can also be emitted from anthropogenic and biogenic sources and/or produced by photochemical reactions. Long-range transport from the Asian continent may also contribute to the seasonal variation of the wet MMHg deposition flux.

  17. Secondary acidification: Changes in gas-aerosol partitioning of semivolatile nitric acid and enhancement of its deposition due to increased emission and concentration of SOx

    NASA Astrophysics Data System (ADS)

    Kajino, Mizuo; Ueda, Hiromasa; Nakayama, Shinji

    2008-02-01

    Secondary acidification, or the indirect enhancement of semivolatile air pollutant deposition associated with increased SO42- concentrations, is shown to occur in general air pollution using data collected from six stations of the Acid Deposition Monitoring Network in East Asia (EANET) in Japan. This effect was first detected as a result of volcanic SO2 plumes in our previous studies. Results indicate that as SO42- concentration increases, gas-aerosol partitioning of nitric acid shifts to the gas phase, increasing the HNO3 gas concentration. Since the dry and wet deposition rates of HNO3 gas are very high, deposition can be enhanced even when the emission of NOx remains unchanged. In western Japan, the indirect effect for wet deposition is most apparent from spring to autumn, when the Asian continental outflow carries sulfate-rich contaminated air masses. However, it is not pronounced in air masses containing abundant sea-salt particles and related cation components in aerosols. In areas such as forests or farmlands with low surface resistance, dry deposition of nitric acid is more pronounced than wet deposition as the dry deposition velocity of HNO3 gas is high. Increased dry deposition of t-NO3 due to the indirect effect and consequent vegetation damage is thus of considerable concern in such regions. The deposition of other semivolatile components, such as hydrochloric acid and ammonia, can be altered and can also induce secondary acidification.

  18. Model study on acidifying wet deposition in East Asia during wintertime

    NASA Astrophysics Data System (ADS)

    Han, Zhiwei; Ueda, Hiromasa; Sakurai, Tatsuya

    A regional air quality model (RAQM) has been developed and applied together with an aerosol model to investigate the states and characteristics of wet deposition in East Asia in December 2001. Model simulation is performed with monthly based emission inventory [Streets, D.G., Bond, T.C., Carmichael, G.R., Fernandes, S.D., Fu, Q., He, D., Klimont, Z., Nelson, S. M., Tsai, N.Y., Wang, M.Q., Woo, J.-H., Yarber, K.F., 2003. An inventory of gaseous and primary emissions in Asia in the year 2000. Journal of Geophysical Research 108(D21), 8809] and meteorological fields derived from MM5. Model results are compared with extensive monitoring data including relevant gaseous species and ions in precipitation. The validation demonstrates that this model system is able to represent most of the major physical and chemical processes involved in acid deposition and reproduces concentrations reasonably well, within a factor of 2 of observations in general. The study shows that the regions with pH less than 4.5 are mainly located in southwestern China, parts of the Yangtze Delta, the Yellow Sea and the Korean peninsula, indicating wide regions of acid precipitation in East Asia in wintertime. Japan islands mainly exhibit pH values of 4.5-5.0, whereas over wide areas of northern China, pH values are relatively high (⩾5.0) due to neutralization by alkaline materials such as calcium-laden particles and ammonia, which are more abundant in northern China than that in southern China. While acid rain over most of China is still characterized by sulfur-induced type, considerable areas of eastern China and the western Pacific Rim are found to be more affected by nitric acid than sulfuric acid in acidification of precipitation, which is supposed to result from a combined effect of variations in photochemistry and emission, suggesting the increasing importance of NO x emission in these regions.

  19. [Atmospheric dry and wet nitrogen deposition in typical agricultural areas of North Shaanxi].

    PubMed

    Wei, Yang; Tong, Yan-An; Duan, Min; Qiao, Li; Tian, Hong-Wei; Lei, Xiao-Ying; Ma, Wen-Juan

    2010-01-01

    To investigate the farmland soil nitrogen input from atmospheric dry and wet deposition, a 1-year observation was conducted in the Yulin and Luochuan areas of North Shaanxi Province from June 2007 to May 2008. The total inorganic nitrogen (TIN) deposition in Yulin and Luochuan was 22.17 and 16.95 kg x hm(-2) x a(-1), among which, wet deposition accounted for 95.1% and 90.4%, while dry deposition accounted for 4.9% and 9.6%, respectively, illustrating that the nitrogen deposition in both Yulin and Luochuan was mainly come from wet deposition. In the TIN deposition, the amount of nitrate in Yulin and Luochuan was 12.22 and 9.24 kg x hm(-2) xa(-1), accounting for 55.1% and 54.5%, respectively. The amount of wet deposition and the percentage of nitrate in TIN deposition were higher in Yulin than in Luochuan, because of the differences in pollution level, weather condition, and underlying surface characteristics.

  20. Aerosol Deposition to Hyperarid Soils of the Atacama Desert

    NASA Astrophysics Data System (ADS)

    Ewing, S. A.; Stewart, B. W.; Kendall, C.; McKay, C. P.; Amundson, R. G.

    2003-12-01

    The influence of atmospheric deposition in most soils is difficult to establish due to leaching and biogeochemical transformations. In contrast, the soils of the Atacama Desert in northern Chile reflect a long-term history of atmospheric deposition that is arguably not preserved elsewhere on Earth. In order to determine the mass and origin of salts accumulated, we present isotopic and chemical data for soils and aerosols along a climate gradient from the extreme hyperarid core of the Atacama (< 5 mm y-1), to sites that receive slightly more rain (up to 15 mm y-1). In the driest region, accumulation of aerosol-derived salts has caused nearly 500% volumetric expansion of the soil. Here we focus on the origin of two of the most important salts: gypsum (calcium sulfate) and sodium nitrate. Water-soluble 87Sr/86Sr decreases with depth, indicating changing sources of sulfate-associated Ca. Sulfate δ 34S also decreases with depth, indicating either isotopic fractionation with downward transport or changing sources of sulfate with time. Water-soluble 87Sr/86Sr values are higher than those reported for local granitic rocks, as might be expected with very limited weathering, and lower than the value reported by Rech et al. (2003) for pedogenic gypsum at a nearby site. While near-surface sulfate δ 34S values imply a marine component, our observed 87Sr/86Sr values fall within the range observed for sulfate salts from salars to the east, suggesting that water-soluble soil Ca contains a significant continental component that may increase or vary in origin with depth in the profile (and thus distance of transport). Nitrate concentrations and nitrate δ 15N values increase with depth, as would be predicted by a advection/reaction model of downward nitrate transport. In soils with increasing precipitation, overall nitrate concentrations are dramatically reduced and overall sulfate concentrations decrease, occurring at greater soil depths. In aerosol samples, nitrate is present at

  1. A GCM investigation of impact of aerosols on the precipitation in Amazon during the dry to wet transition

    NASA Astrophysics Data System (ADS)

    Gu, Yu; Liou, K. N.; Jiang, J. H.; Fu, R.; Lu, Sarah; Xue, Y.

    2016-06-01

    The climatic effects of aerosols on the precipitation over the Amazon during the dry to wet transition period have been investigated using an atmospheric general circulation model, NCEP/AGCM, and the aerosol climatology data. We found increased instability during the dry season and delayed wet season onset with aerosols included in the model simulation, leading to the delay of the maximum precipitation over the Amazon by about half a month. In particular, our GCM simulations show that surface solar flux is reduced in the Amazon due to the absorption and scattering of the solar radiation by aerosols, leading to decreased surface temperature. Reduced surface solar flux is balanced by decreases in both surface sensible heat and latent heat fluxes. During the wet season, the subtropical system over the Amazon has a shallower convection. With the inclusion of aerosols in the simulation, precipitation in the rainy season over the Amazon decreases in the major rainfall band, which partially corrects the overestimate of the simulated precipitation in that region. The reduced surface temperature by aerosols is also coupled with a warming in the middle troposphere, leading to increased atmosphere stability and moisture divergence over the Amazon. However, during the dry season when the convective system is stronger over the Amazon, rainfall increases in that region due to the warming of the air over the upper troposphere produced by biomass burning aerosols, which produces an anomalous upward motion and a convergence of moisture flux over the Amazon and draws the moisture and precipitation further inland. Therefore, aerosol effects on precipitation depend on the large-scale atmospheric stability, resulting in their different roles over the Amazon during the dry and wet seasons.

  2. Parallel measurements of organic and elemental carbon dry (PM1, PM2.5) and wet (rain, snow, mixed) deposition into the Baltic Sea.

    PubMed

    Witkowska, Agnieszka; Lewandowska, Anita; Falkowska, Lucyna M

    2016-03-15

    Parallel studies on organic and elemental carbon in PM1 and PM2.5 aerosols and in wet deposition in various forms of its occurrence were conducted in the urbanised coastal zone of the Baltic Sea. The carbon load introduced into the sea water was mainly affected by the form of precipitation. Dry deposition load of carbon was on average a few orders of magnitude smaller than wet deposition. The suspended organic carbon was more effectively removed from the air with rain than snow, while an inverse relationship was found for elemental carbon. However the highest flux of water insoluble organic carbon was recorded in precipitation of a mixed nature. The atmospheric cleaning of highly dissolved organic carbon was observed to be the most effective on the first day of precipitation, while the hydrophobic elemental carbon was removed more efficiently when the precipitation lasted longer than a day.

  3. High Mercury Wet Deposition at a "Clean Air" Site in Puerto Rico.

    PubMed

    Shanley, James B; Engle, Mark A; Scholl, Martha; Krabbenhoft, David P; Brunette, Robert; Olson, Mark L; Conroy, Mary E

    2015-10-20

    Atmospheric mercury deposition measurements are rare in tropical latitudes. Here we report on seven years (April 2005 to April 2012, with gaps) of wet Hg deposition measurements at a tropical wet forest in the Luquillo Mountains, northeastern Puerto Rico, U.S. Despite receiving unpolluted air off the Atlantic Ocean from northeasterly trade winds, during two complete years the site averaged 27.9 μg m(-2) yr(-1) wet Hg deposition, or about 30% more than Florida and the Gulf Coast, the highest deposition areas within the U.S. These high Hg deposition rates are driven in part by high rainfall, which averaged 2855 mm yr(-1). The volume-weighted mean Hg concentration was 9.8 ng L(-1), and was highest during summer and lowest during the winter dry season. Rainout of Hg (decreasing concentration with increasing rainfall depth) was minimal. The high Hg deposition was not supported by gaseous oxidized mercury (GOM) at ground level, which remained near global background concentrations (<10 pg m(-3)). Rather, a strong positive correlation between Hg concentrations and the maximum height of rain detected within clouds (echo tops) suggests that droplets in high convective cloud tops scavenge GOM from above the mixing layer. The high wet Hg deposition at this "clean air" site suggests that other tropical areas may be hotspots for Hg deposition as well.

  4. High mercury wet deposition at a “clean Air” site in Puerto Rico

    USGS Publications Warehouse

    Shanley, James B.; Engle, Mark A.; Scholl, Martha A.; Krabbenhoft, David P.; Brunette, Robert; Olson, Mark L.; Conroy, Mary E.

    2015-01-01

    Atmospheric mercury deposition measurements are rare in tropical latitudes. Here we report on seven years (April 2005 to April 2012, with gaps) of wet Hg deposition measurements at a tropical wet forest in the Luquillo Mountains, northeastern Puerto Rico, U.S. Despite receiving unpolluted air off the Atlantic Ocean from northeasterly trade winds, during two complete years the site averaged 27.9 μg m–2 yr–1 wet Hg deposition, or about 30% more than Florida and the Gulf Coast, the highest deposition areas within the U.S. These high Hg deposition rates are driven in part by high rainfall, which averaged 2855 mm yr–1. The volume-weighted mean Hg concentration was 9.8 ng L–1, and was highest during summer and lowest during the winter dry season. Rainout of Hg (decreasing concentration with increasing rainfall depth) was minimal. The high Hg deposition was not supported by gaseous oxidized mercury (GOM) at ground level, which remained near global background concentrations (<10 pg m–3). Rather, a strong positive correlation between Hg concentrations and the maximum height of rain detected within clouds (echo tops) suggests that droplets in high convective cloud tops scavenge GOM from above the mixing layer. The high wet Hg deposition at this “clean air” site suggests that other tropical areas may be hotspots for Hg deposition as well.

  5. Atmospheric wet and litterfall mercury deposition at urban and rural sites in China

    NASA Astrophysics Data System (ADS)

    Fu, Xuewu; Yang, Xu; Lang, Xiaofang; Zhou, Jun; Zhang, Hui; Yu, Ben; Yan, Haiyu; Lin, Che-Jen; Feng, Xinbin

    2016-09-01

    Mercury (Hg) concentrations and deposition fluxes in precipitation and litterfall were measured at multiple sites (six rural sites and an urban site) across a broad geographic area in China. The annual deposition fluxes of Hg in precipitation at rural sites and an urban site were 2.0 to 7.2 and 12.6 ± 6.5 µg m-2 yr-1, respectively. Wet deposition fluxes of Hg at rural sites showed a clear regional difference with elevated deposition fluxes in the subtropical zone, followed by the temporal zone and arid/semi-arid zone. Precipitation depth is the primary influencing factor causing the variation of wet deposition. Hg fluxes through litterfall ranged from 22.8 to 62.8 µg m-2 yr-1, higher than the wet deposition fluxes by a factor of 3.9 to 8.7 and representing approximately 75 % of the total Hg deposition at the forest sites in China. This suggests that uptake of atmospheric Hg by foliage is the dominant pathway to remove atmospheric Hg in forest ecosystems in China. Wet deposition fluxes of Hg at rural sites of China were generally lower compared to those in North America and Europe, possibly due to a combination of lower precipitation depth, lower GOM concentrations in the troposphere and the generally lower cloud base heights at most sites that wash out a smaller amount of GOM and PBM during precipitation events.

  6. Evidence for a free troposphere source of mercury in wet deposition in the Western United States.

    PubMed

    Huang, Jiaoyan; Gustin, Mae Sexauer

    2012-06-19

    Mercury (Hg) in wet deposition in the United States is measured as part of the National Atmospheric Deposition Program--Hg Deposition Network (MDN). This study focused on compiling and assessing data collected since 2003 at two sites in Nevada, and at one in Nevada and three in Idaho where data were collected over shorter time intervals. At all locations the highest volume weighted concentrations and deposition were observed in the summer, a time of low precipitation, but high gaseous oxidized Hg (GOM) concentrations. Detailed assessment of high Hg wet deposition events showed variability across the region and higher deposition at the higher elevation sites. Potential Source Contribution Function analyses showed no specific point sources associated with the high Hg wet deposition events, but air masses derived predominantly from the southwest. Although this region has potential local and regional sources of GOM, detailed back trajectory analyses, the environmental setting of Nevada, results from other studies in Nevada, and GEOS-Chem modeling results point toward a free troposphere contribution to mercury in wet deposition input to this area of the western United States.

  7. Wet deposition of ammonium, nitrate and sulfate in the Netherlands over the period 1992-2008

    NASA Astrophysics Data System (ADS)

    van der Swaluw, Eric; Asman, Willem A. H.; van Jaarsveld, Hans; Hoogerbrugge, Ronald

    2011-07-01

    We present measurements of wet deposition of ammonium, nitrate and sulfate in the Netherlands over the period 1992-2008. These data series are obtained from the Dutch National Precipitation Chemistry Monitoring Network which consists of 11 monitoring stations which are homogeneously spread over the Netherlands. These long-term measurements allow for a trend analysis over this period, which are to a large extent not influenced by the year to year variations in meteorological circumstances. It is shown that the downward trend of ammonium, nitrate and sulfate wet deposition over the period 1992-2008 are statistically significant: the wet deposition in the Netherlands decreased in the period 1992-2008 by 37% for ammonium, 28% for nitrate and 59% for sulfate. A comparison between the measurements and emissions are made in order to check whether the emissions show similar downward trends. Subsequently a comparison is made between measured and calculated wet deposition fluxes. These calculation results were performed with the Operational Priority Substances (OPS-model). The trends in both the emissions and the calculated wet deposition fluxes show good agreement for all three measured components. It is therefore concluded that the downward trends of the wet deposition fluxes are a direct effect of the decrease of emissions. Finally, it is shown that the relative downward trend of the wet deposition fluxes of sulfate in the Netherlands shows a large-scale structure with a gradient running from east to west. A similar pattern is seen in the simulations performed with the OPS-model.

  8. Atmospheric wet and dry deposition of trace elements at ten sites in Northern China

    NASA Astrophysics Data System (ADS)

    Pan, Y. P.; Wang, Y. S.

    2014-08-01

    Atmospheric deposition is considered to be a major process that removes pollutants from the atmosphere and an important source of nutrients and contaminants for ecosystems. Trace elements (TEs), especially toxic metals deposited on plants and into soil and water, can cause substantial damage to the environment and human health due to their transfer and accumulation in food chains. Despite public concerns, quantitative knowledge of metal deposition from the atmosphere to ecosystems remains scarce. To advance our understanding of the spatio-temporal variations in the magnitudes, pathways, compositions and impacts of atmospherically deposited TEs, precipitation (rain and snow) and dry-deposited particles were collected simultaneously at ten sites in Northern China from December 2007 to November 2010. The measurements showed that the wet and dry depositions of TEs in the target areas were orders of magnitude higher than previous observations within and outside China, generating great concern over the potential risks. The spatial distribution of the total (wet plus dry) deposition flux was consistent with that of the dry deposition, with a significant decrease from industrial and urban areas to suburban, agricultural and rural sites. In contrast, the wet deposition exhibited less spatial variation. The seasonal variation of wet deposition was also different from that of dry deposition, although they were both governed by the precipitation and emission patterns. For the majority of TEs that exist as coarse particles, dry deposition dominated the total flux at each site. This was not the case for K, Ni, As, Pb, Zn, Cd, Se, Ag and Tl, for which the relative importance between wet and dry deposition fluxes varied by site. Whether wet deposition is the major atmospheric cleansing mechanism for the TEs depends on the size distribution and solubility of the particles. We found that atmospheric inputs of Cu, Pb, Zn, Cd, As and Se were of the same magnitude as their increases in

  9. Atmospheric wet and dry deposition of trace elements at 10 sites in Northern China

    NASA Astrophysics Data System (ADS)

    Pan, Y. P.; Wang, Y. S.

    2015-01-01

    Atmospheric deposition is considered to be a major process that removes pollutants from the atmosphere and an important source of nutrients and contaminants for ecosystems. Trace elements (TEs), especially toxic metals deposited on plants and into soil or water, can cause substantial damage to the environment and human health due to their transfer and accumulation in food chains. Despite public concerns, quantitative knowledge of metal deposition from the atmosphere to ecosystems remains scarce. To advance our understanding of the spatiotemporal variations in the magnitudes, pathways, compositions and impacts of atmospherically deposited TEs, precipitation (rain and snow) and dry-deposited particles were collected simultaneously at 10 sites in Northern China from December 2007 to November 2010. The measurements showed that the wet and dry depositions of TEs in the target areas were orders of magnitude higher than previous observations within and outside China, generating great concern over the potential risks. The spatial distribution of the total (wet plus dry) deposition flux was consistent with that of the dry deposition, with a significant decrease from industrial and urban areas to suburban, agricultural and rural sites, while the wet deposition exhibited less spatial variation. In addition, the seasonal variation of wet deposition was also different from that of dry deposition, although they were both governed by the precipitation and emission patterns. For the majority of TEs that exist as coarse particles, dry deposition dominated the total flux at each site. This was not the case for potassium, nickel, arsenic, lead, zinc, cadmium, selenium, silver and thallium, for which the relative importance between wet and dry deposition fluxes varied by site. Whether wet deposition is the major atmospheric cleansing mechanism for the TEs depends on the size distribution of the particles. We found that atmospheric inputs of copper, lead, zinc, cadmium, arsenic and

  10. Simulating Wet Deposition of Radiocesium from the Chernobyl Accident

    DTIC Science & Technology

    2001-03-01

    In response to the Chernobyl nuclear power plant accident of 1986, a cesium-137 deposition dataset was assembled. Most of the airborne Chernobyl ... Chernobyl cesium-137. A cloud base parameterization modification is tested and appears to slightly improve the accuracy of one HYSPLIT simulation of...daily Chernobyl cesium-137 deposition over the course of the accident at isolated European sites, and degrades the accuracy of another HYSPLIT simulation

  11. Atomic layer deposition and abrupt wetting transitions on nonwoven polypropylene and woven cotton fabrics.

    PubMed

    Hyde, G Kevin; Scarel, Giovanna; Spagnola, Joseph C; Peng, Qing; Lee, Kyoungmi; Gong, Bo; Roberts, Kim G; Roth, Kelly M; Hanson, Christopher A; Devine, Christina K; Stewart, S Michael; Hojo, Daisuke; Na, Jeong-Seok; Jur, Jesse S; Parsons, Gregory N

    2010-02-16

    Atomic layer deposition (ALD) of aluminum oxide on nonwoven polypropylene and woven cotton fabric materials can be used to transform and control fiber surface wetting properties. Infrared analysis shows that ALD can produce a uniform coating throughout the nonwoven polypropylene fiber matrix, and the amount of coating can be controlled by the number of ALD cycles. Upon coating by ALD aluminum oxide, nonwetting hydrophobic polypropylene fibers transition to either a metastable hydrophobic or a fully wetting hydrophilic state, consistent with well-known Cassie-Baxter and Wenzel models of surface wetting of roughened surfaces. The observed nonwetting/wetting transition depends on ALD process variables such as the number of ALD coating cycles and deposition temperature. Cotton fabrics coated with ALD aluminum oxide at moderate temperatures were also observed to transition from a natural wetting state to a metastable hydrophobic state and back to wetting depending on the number of ALD cycles. The transitions on cotton appear to be less sensitive to deposition temperature. The results provide insight into the effect of ALD film growth mechanisms on hydrophobic and hydrophilic polymers and fibrous structures. The ability to adjust and control surface energy, surface reactivity, and wettability of polymer and natural fiber systems using atomic layer deposition may enable a wide range of new applications for functional fiber-based systems.

  12. Episodic response project: Wet deposition at watersheds in three regions of the eastern United States

    SciTech Connect

    Barchet, W.R.

    1991-11-01

    During the period from August 1988 to June 1990, wet-only sampling of precipitation was carried out at three Episodic Response Project sites and at one supplemental site. The three watershed sites are Moss Lake, Biscuit Brook, and Linn Run. The supplemental site was the MAP3S site at Pennsylvania State University that characterizes the central group of northern Appalachian streams. The site operators adhered by varying degrees to the sample collection protocol based on the daily sampling protocol of the MAP3S Precipitation Chemistry Network. Sulfate and nitrate ion together accounted for more than 80% of total anions (in {mu}Eq/L) in the precipitation at all sites. Wet deposition of sulfate at Moss Lake, Biscuit Brook, Penn State, and Linn Run averaged 223, 230, 253, and 402 mg/m{sup 2}/month, respectively, whereas nitrate wet deposition averaged 197, 195, 160, and 233 mg/m{sup 2}/month, respectively. Sulfate deposition was a factor of 2 to 4 higher in summer than in winter. The seasonal pattern for nitrate deposition was weak; the seasonal contrast was less than a factor of 2.5 at all sites. The association between the wet deposition and precipitation chemistry at the MAP3S monitoring site and the average for the study watersheds was dependent on the distance between the site and watershed and the intervening terrain. Precipitation chemistry at the monitoring site is representative of that at the ERP study watersheds in the Adirondack and Catskill regions and in the south-western group of watersheds in the Appalachian region. High spatial variability in precipitation amounts makes this assumption weaker for wet deposition. Chemical input to watersheds from dry deposition has not been determined at any site but could range from a factor of 0.3 to 1.0 of the wet deposition. 7 refs., 38 figs., 12 tabs.

  13. Atmospheric wet deposition of trace elements to a suburban environment, Reston, Virginia, USA

    USGS Publications Warehouse

    Conko, Kathryn M.; Rice, Karen C.; Kennedy, Margaret M.

    2004-01-01

    Wet deposition from a suburban area in Reston, Virginia was collected during 1998 and analyzed to assess the anion and trace-element concentrations and depositions. Suburban Reston, approximately 26 km west of Washington, DC, is densely populated and heavily developed. Wet deposition was collected bi-weekly in an automated collector using trace-element clean sampling and analytical techniques. The annual volume-weighted concentrations of As, Cd, and Pb were similar to those previously reported for a remote site on Catoctin Mt., Maryland (70 km northwest), which indicated a regional signal for these elements. The concentrations and depositions of Cu and Zn at the suburban site were nearly double those at remote sites because of the influence of local vehicular traffic. The 1998 average annual wet deposition (μg m−2 yr−1) was calculated for Al (52,000), As (94), Cd (54), Cr (160), Cu (700), Fe (23,000), Mn (2000), Ni (240), Pb (440), V (430), and Zn (4100). The average annual wet deposition (meq m−2 yr−1) was calculated for H+ (74), Cl− (8.5), NO3− (33), and SO42− (70). Analysis of digested total trace-element concentrations in a subset of samples showed that the refractory elements in suburban precipitation comprised a larger portion of the total deposition of trace elements than in remote areas.

  14. Annual variations in wet-deposition chemistry related to changes in climate

    NASA Astrophysics Data System (ADS)

    Wetherbee, Gregory A.; Mast, M. Alisa

    2016-11-01

    National Atmospheric Deposition Program (NADP)/National Trends Network precipitation type, snow-season duration, and annual timing of selected chemical wet-deposition maxima vary with latitude and longitude within a 35-year (1979-2013) data record for the contiguous United States and Alaska. From the NADP data collected within the region bounded by 35.6645°-48.782° north latitude and 124°-68° west longitude, similarities in latitudinal and longitudinal patterns of changing snow-season duration, fraction of annual precipitation recorded as snow, and the timing of chemical wet-deposition maxima, suggest that the chemical climate of the atmosphere is linked to physical changes in climate. Total annual precipitation depth has increased 4-6 % while snow season duration has decreased from approximately 7 to 21 days across most of the USA, except in higher elevation regions where it has increased by as much as 21 days. Snow-season precipitation is increasingly comprised of snow, but annually total precipitation is increasingly comprised of liquid precipitation. Meanwhile, maximum ammonium deposition occurs as much as 27 days earlier, and the maximum nitrate: sulfate concentration ratio in wet-deposition occurs approximately 10-21 days earlier in the year. The maximum crustal (calcium + magnesium + potassium) cation deposition occurs 2-35 days earlier in the year. The data suggest that these shifts in the timing of atmospheric wet deposition are linked to a warming climate, but the ecological consequences are uncertain.

  15. Particle Deposition in a Child Respiratory Tract Model: In Vivo Regional Deposition of Fine and Ultrafine Aerosols in Baboons

    PubMed Central

    Albuquerque-Silva, Iolanda; Vecellio, Laurent; Durand, Marc; Avet, John; Le Pennec, Déborah; de Monte, Michèle; Montharu, Jérôme; Diot, Patrice; Cottier, Michèle; Dubois, Francis; Pourchez, Jérémie

    2014-01-01

    To relate exposure to adverse health effects, it is necessary to know where particles in the submicron range deposit in the respiratory tract. The possibly higher vulnerability of children requires specific inhalation studies. However, radio-aerosol deposition experiments involving children are rare because of ethical restrictions related to radiation exposure. Thus, an in vivo study was conducted using three baboons as a child respiratory tract model to assess regional deposition patterns (thoracic region vs. extrathoracic region) of radioactive polydisperse aerosols ([d16–d84], equal to [0.15 µm–0.5 µm], [0.25 µm–1 µm], or [1 µm–9 µm]). Results clearly demonstrated that aerosol deposition within the thoracic region and the extrathoraic region varied substantially according to particle size. High deposition in the extrathoracic region was observed for the [1 µm–9 µm] aerosol (72%±17%). The [0.15 µm–0.5 µm] aerosol was associated almost exclusively with thoracic region deposition (84%±4%). Airborne particles in the range of [0.25 µm–1 µm] showed an intermediate deposition pattern, with 49%±8% in the extrathoracic region and 51%±8% in the thoracic region. Finally, comparison of baboon and human inhalation experiments for the [1 µm–9 µm] aerosol showed similar regional deposition, leading to the conclusion that regional deposition is species-independent for this airborne particle sizes. PMID:24787744

  16. Particle deposition in a child respiratory tract model: in vivo regional deposition of fine and ultrafine aerosols in baboons.

    PubMed

    Albuquerque-Silva, Iolanda; Vecellio, Laurent; Durand, Marc; Avet, John; Le Pennec, Déborah; de Monte, Michèle; Montharu, Jérôme; Diot, Patrice; Cottier, Michèle; Dubois, Francis; Pourchez, Jérémie

    2014-01-01

    To relate exposure to adverse health effects, it is necessary to know where particles in the submicron range deposit in the respiratory tract. The possibly higher vulnerability of children requires specific inhalation studies. However, radio-aerosol deposition experiments involving children are rare because of ethical restrictions related to radiation exposure. Thus, an in vivo study was conducted using three baboons as a child respiratory tract model to assess regional deposition patterns (thoracic region vs. extrathoracic region) of radioactive polydisperse aerosols ([d16-d84], equal to [0.15 µm-0.5 µm], [0.25 µm-1 µm], or [1 µm-9 µm]). Results clearly demonstrated that aerosol deposition within the thoracic region and the extrathoraic region varied substantially according to particle size. High deposition in the extrathoracic region was observed for the [1 µm-9 µm] aerosol (72% ± 17%). The [0.15 µm-0.5 µm] aerosol was associated almost exclusively with thoracic region deposition (84% ± 4%). Airborne particles in the range of [0.25 µm-1 µm] showed an intermediate deposition pattern, with 49% ± 8% in the extrathoracic region and 51% ± 8% in the thoracic region. Finally, comparison of baboon and human inhalation experiments for the [1 µm-9 µm] aerosol showed similar regional deposition, leading to the conclusion that regional deposition is species-independent for this airborne particle sizes.

  17. Background wet deposition of mercury in Great Britain.

    PubMed

    Rowland, A P; Lawlor, A J; Guyatt, H J; Wadsworth, R A

    2010-09-01

    Precipitation samples have been collected on a monthly basis from a network of 10 sites in Great Britain (GB) in order to estimate background mercury (Hg) deposition in the rural environment. Collection started in February 2005 and results presented here cover the period up to June 2009. The annual volume-weighted mean (AVWM) Hg concentrations range from 1.0 ng L(-1) at Cockley Beck in the Lake District in 2006 to 8.8 ng L(-1) at Heigham Holmes on the Norfolk Coast England in 2008. The largest validated solution concentrations were 33.7 ng L(-1) Hg measured at Cockley Beck in May 2008. The large difference in rainfall amount between sites means that the remote site at Cockley Beck has both the lowest long-term AVWM concentration (1.6 ng L(-1)) and the greatest annual flux is greatest at 43 mg ha(-1) yr(-1). Predicted deposition tends to be much greater in western Britain where the greater rainfall occurs. Because some observations are very close to the analytical detection limit (1.0 ng L(-1)), rigorous cleaning procedures, the use of replicate samplers to monitor contamination, and the inclusion of 'bottle blanks' are required to obtain valid measurements of Hg in the bulk deposition. Deposition in rural sites is equivalent to about 10% of the estimated magnitude of known emissions in GB.

  18. Wet Deposition of Perchlorate Over the Continental United States

    NASA Astrophysics Data System (ADS)

    Rajagopalan, S.; Jackson, A. W.; Anderson, T. A.

    2007-12-01

    Natural perchlorate (ClO4-) has been detected in soil, vegetation, food products, and ground and drinking water supplies at various concentrations across the world. For almost a century natural perchlorate has been known to exist in Chilean nitrate deposits that are up to 16 million years old, and recent isotopic evidence has confirmed its source to be predominantly atmospheric. Although the source of natural perchlorate has been attributed to atmospheric deposition, there is almost no data available concerning the deposition rate of perchlorate from precipitation. This research effort, supported by SERDP, was designed to investigate the range of concentrations, and temporal and spatial variations in perchlorate deposition. Sub-samples of precipitation collected through the National Atmospheric Deposition program over a two year period were analyzed for perchlorate. Sample locations included 14 continental states, and Puerto Rico. Perchlorate has been detected (DL= 5 ng/L) in over 65 % of all samples tested with a mean value of 12.60 ± 13.60 ng/L and ranged from < 5 ng/L to 75 ng/L with higher concentrations predominantly in summer months and inland regions. The Cl- /ClO4- molar ratio varied over three orders of magnitude with few thousands inland to few millions near coastal regions. There were no significant correlations (r > 0.5) between ClO4- and other ions (Cl-, NO3-, SO4-2, Na+, K+, Ca+2, Mg+2, and NH4+). Results from this study will have important implications to the national perchlorate issue and may aid in explaining the occurrence of non-anthropogenic perchlorate being reported in arid and semi-arid areas.

  19. Improved mapping of National Atmospheric Deposition Program wet-deposition in complex terrain using PRISM-gridded data sets

    USGS Publications Warehouse

    Latysh, Natalie E.; Wetherbee, Gregory Alan

    2012-01-01

    High-elevation regions in the United States lack detailed atmospheric wet-deposition data. The National Atmospheric Deposition Program/National Trends Network (NADP/NTN) measures and reports precipitation amounts and chemical constituent concentration and deposition data for the United States on annual isopleth maps using inverse distance weighted (IDW) interpolation methods. This interpolation for unsampled areas does not account for topographic influences. Therefore, NADP/NTN isopleth maps lack detail and potentially underestimate wet deposition in high-elevation regions. The NADP/NTN wet-deposition maps may be improved using precipitation grids generated by other networks. The Parameter-elevation Regressions on Independent Slopes Model (PRISM) produces digital grids of precipitation estimates from many precipitation-monitoring networks and incorporates influences of topographical and geographical features. Because NADP/NTN ion concentrations do not vary with elevation as much as precipitation depths, PRISM is used with unadjusted NADP/NTN data in this paper to calculate ion wet deposition in complex terrain to yield more accurate and detailed isopleth deposition maps in complex terrain. PRISM precipitation estimates generally exceed NADP/NTN precipitation estimates for coastal and mountainous regions in the western United States. NADP/NTN precipitation estimates generally exceed PRISM precipitation estimates for leeward mountainous regions in Washington, Oregon, and Nevada, where abrupt changes in precipitation depths induced by topography are not depicted by IDW interpolation. PRISM-based deposition estimates for nitrate can exceed NADP/NTN estimates by more than 100% for mountainous regions in the western United States.

  20. Improved mapping of National Atmospheric Deposition Program wet-deposition in complex terrain using PRISM-gridded data sets.

    PubMed

    Latysh, Natalie E; Wetherbee, Gregory Alan

    2012-01-01

    High-elevation regions in the United States lack detailed atmospheric wet-deposition data. The National Atmospheric Deposition Program/National Trends Network (NADP/NTN) measures and reports precipitation amounts and chemical constituent concentration and deposition data for the United States on annual isopleth maps using inverse distance weighted (IDW) interpolation methods. This interpolation for unsampled areas does not account for topographic influences. Therefore, NADP/NTN isopleth maps lack detail and potentially underestimate wet deposition in high-elevation regions. The NADP/NTN wet-deposition maps may be improved using precipitation grids generated by other networks. The Parameter-elevation Regressions on Independent Slopes Model (PRISM) produces digital grids of precipitation estimates from many precipitation-monitoring networks and incorporates influences of topographical and geographical features. Because NADP/NTN ion concentrations do not vary with elevation as much as precipitation depths, PRISM is used with unadjusted NADP/NTN data in this paper to calculate ion wet deposition in complex terrain to yield more accurate and detailed isopleth deposition maps in complex terrain. PRISM precipitation estimates generally exceed NADP/NTN precipitation estimates for coastal and mountainous regions in the western United States. NADP/NTN precipitation estimates generally exceed PRISM precipitation estimates for leeward mountainous regions in Washington, Oregon, and Nevada, where abrupt changes in precipitation depths induced by topography are not depicted by IDW interpolation. PRISM-based deposition estimates for nitrate can exceed NADP/NTN estimates by more than 100% for mountainous regions in the western United States.

  1. QUALITY ASSURANCE PROGRAM FOR WET DEPOSITION SAMPLING AND CHEMICAL ANALYSES FOR THE NATIONAL TRENDS NETWORK.

    USGS Publications Warehouse

    Schroder, LeRoy J.; Malo, Bernard A.; ,

    1985-01-01

    The purpose of the National Trends Network is to delineate the major inorganic constituents in the wet deposition in the United States. The approach chosen to monitor the Nation's wet deposition is to install approximately 150 automatic sampling devices with at least one collector in each state. Samples are collected at one week intervals, removed from collectors, and transported to an analytical laboratory for chemical analysis. The quality assurance program has divided wet deposition monitoring into 5 parts: (1) Sampling site selection, (2) sampling device, (3) sample container, (4) sample handling, and (5) laboratory analysis. Each of these five components is being examined using existing designs or new designs. Each existing or proposed sampling site is visited and a criteria audit is performed.

  2. Modeling dry and wet deposition of sulfate, nitrate, and ammonium ions in Jiuzhaigou National Nature Reserve, China using a source-oriented CMAQ model: Part II. Emission sector and source region contributions.

    PubMed

    Qiao, Xue; Tang, Ya; Kota, Sri Harsha; Li, Jingyi; Wu, Li; Hu, Jianlin; Zhang, Hongliang; Ying, Qi

    2015-11-01

    A source-oriented Community Multiscale Air Quality (CMAQ) model driven by the meteorological fields generated by the Weather Research and Forecasting (WRF) model was used to study the dry and wet deposition of nitrate (NO3(-)), sulfate (SO4(2-)), and ammonium (NH4(+)) ions in the Jiuzhaigou National Nature Reserve (JNNR), China from June to August 2010 and to identify the contributions of different emission sectors and source regions that were responsible for the deposition fluxes. Contributions from power plants, industry, transportation, domestic, biogenic, windblown dust, open burning, fertilizer, and manure management sources to deposition fluxes in JNNR watershed and four EANET sites are determined. In JNNR, 96%, 82%, and 87% of the SO4(2-), NO3(-) and NH4(+) deposition fluxes are in the form of wet deposition of the corresponding aerosol species. Industry and power plants are the two major sources of SO4(2-) deposition flux, accounting for 86% of the total wet deposition of SO4(2-), and industry has a higher contribution (56%) than that of power plants (30%). Power plants and industry are also the top sources that are responsible for NO3(-) wet deposition, and contributions from power plants (30%) are generally higher than those from industries (21%). The major sources of NH4(+) wet deposition flux in JNNR are fertilizer (48%) and manure management (39%). Source-region apportionment confirms that SO2 and NOx emissions from local and two nearest counties do not have a significant impact on predicted wet deposition fluxes in JNNR, with contributions less than 10%. While local NH3 emissions account for a higher fraction of the NH4(+) deposition, approximately 70% of NH4(+) wet deposition in JNNR originated from other source regions. This study demonstrates that S and N deposition in JNNR is mostly from long-range transport rather than from local emissions, and to protect JNNR, regional emission reduction controls are needed.

  3. Seasonal chemical composition variations of wet deposition in Urumchi, Northwestern China

    NASA Astrophysics Data System (ADS)

    Xu, Ming; Lü, Aihua; Xu, Feng; Wang, Bin

    Urumchi suffered serious air quality problem in recent years. Although the main air pollutants and wet deposition monitoring have been undertaken by Urumchi Environmental Monitoring Center for many years, researches on chemical composition and variations of wet deposition were not there till now. In this paper, wet deposition monitoring data in Urumchi from 2000 and 2005 were selected to perform this evaluation based on data quality and data integrity. The volume-weighted mean (VWM) concentrations of parameters of wet deposition, namely pH, conductivity, SO 42-, NO 3-, F -, Cl -, NH 4+,Ca 2+, Mg 2+, Na + and K + concentrations, were 6.86 and 91.04 μs cm -1, 14.3, 1.63, 0.37, 3.78, 1.22, 4.79, 0.59, 1.05, 0.74 mg L -1, respectively. Acid precipitation appeared only in wintertime in few cases, and its extreme value was 4.96; the maximum emerged during sand storm event in the non-winter season with the value of 9.35. Wet deposition and air pollution characteristics varied with seasons. In order to make a certainty of possible sources of ions in different seasons, principal component analysis was applied, and conclusions were drawn that in wintertime, the predominant contributor to the wet deposition was coal combustion for residential heating; however, in the non-winter season, the situation was more complicated, dust and soil from outside the urban, dust re-suspension, local industries process, motor vehicle emissions all played their roles.

  4. Continental-scale variation in chloride/bromide ratios of wet deposition.

    PubMed

    Short, M A; de Caritat, P; McPhail, D C

    2017-01-01

    Chlorine and bromine play crucial roles in atmospheric element cycles and are important environmental tracers in catchment investigations, so understanding their distribution at the Earth's near-surface is imperative for deciphering their behaviour. This study presents the first continental-scale analysis of Cl(-) and Br(-) concentrations of wet deposition, based on six and half years of weekly samples collected across North America. A recently developed imputation algorithm was applied to estimate the high proportion of censored Br(-) values, as well as the other eight analytes, based on the multivariate relationships of nine analytes. The results are consistent with previous studies that have found that the concentrations of these two ions in wet deposition, and the Cl(-)/Br(-) ratios of wet deposition decrease with distance inland. Close to the coast, Cl(-)/Br(-) ratios of wet deposition are similar to the ratio found in seawater (~288 by mass), rapidly decrease to approximately a third of the seawater ratio at ~200km inland, and then decrease at a much lesser rate to reach mass-ratios of 20 to 10 at ~1500km inland, following a logarithmic regression. The Niagara Falls and the Great Salt Lake are identified as localised sources of atmospheric solutes based on elevated Cl(-)/Br(-) ratios of wet deposition at proximal sites. Our observations provide further confidence in the findings presented in previous studies that have shown that Cl(-)/Br(-) ratios systematically decrease with increasing distance from the coast, despite the potential confounding impact of other processes, such as weather patterns, chemical behaviour and anthropogenic activity. Our results provide improved estimates of Cl(-)/Br(-) ratios of wet deposition source water in the absence of site-specific data.

  5. The chemical composition and fluxes of atmospheric wet deposition at four sites in South Africa

    NASA Astrophysics Data System (ADS)

    Conradie, E. H.; Van Zyl, P. G.; Pienaar, J. J.; Beukes, J. P.; Galy-Lacaux, C.; Venter, A. D.; Mkhatshwa, G. V.

    2016-12-01

    South Africa is the economic hub of southern Africa and is regarded as an important source region of atmospheric pollutants. A nitrogen dioxide (NO2) hotspot is clearly visible from space over the South African Mpumalanga Highveld, while South Africa is also regarded as the 9th largest anthropogenic sulphur (S) emitting country. Notwithstanding the importance of South Africa with regard to nitrogen (N) and S emissions, very limited data has been published on the chemical composition of wet deposition for this region. This paper presents the concentrations of sodium (Na+), ammonium (NH4+), potassium (K+), calcium (Ca2+), magnesium (Mg2+), nitrate (NO3-), chloride (Cl-), sulphate (SO42-) and water-soluble organic acids (OA) in the wet deposition samples collected between 2009 and 2014 at four South African IDAF (IGAC DEBITS Africa) sites, which are regarded as regional representatives of the north-eastern interior. Also, wet deposition fluxes of the ten ions are calculated and presented in this paper. The results show that the total ionic concentrations and fluxes of wet deposition were much higher at the two sites closer to anthropogenic emissions, while the pH of wet deposition at these two sites were lower compared to that of the two sites that were less impacted by anthropogenic emissions. . The major sources of the ten ions included marine, terrigenous (crust), fossil fuel combustion, agriculture and biomass burning. Significant contributions from fossil fuel combustion were determined for the two sites in close proximity to anthropogenic source regions. The results of back trajectory analysis, however, did indicate that the two remote sites are also affected by air masses passing over the source region through anti-cyclonic recirculation. The largest contributions at the two sites distant from the anthropogenic source regions were marine sources, while the impact of biomass burning was also more significant at the remote sites. Comparison to previous wet

  6. Atmospheric trace elements at Enewetak Atoll: 2. Transport to the ocean by wet and dry deposition

    NASA Astrophysics Data System (ADS)

    Arimoto, R.; Duce, R. A.; Ray, B. J.; Unni, C. K.

    1985-02-01

    The concentrations of trace elements in precipitation and dry deposition are presented for samples collected at Enewetak Atoll (11°N, 162° E) during SEAREX experiments in 1979. The concentrations of Al, Sc, Mn, Fe, Co, and Th in rain are dominated by crustal material, and for these elements, wet deposition evidently exceeds dry deposition. For most of these elements the present rates of atmospheric deposition at Enewetak are similar to their mean rate of accumulation in sediments over the past 5-10,000 years, suggesting that the air-to-sea exchange of particles is closely tied to the sedimentary cycle of the mid-Pacific. Noncrustal sources govern the concentrations of Pb, Zn, Cu, Se, and Cd in wet and dry deposition samples. Analyses of dry deposition collected from a flat plastic plate indicate that the amount of material recycled from the sea surface varies markedly between samples, and even though these estimates do not necessarily reflect the dry deposition to the ocean surface, the results suggest that recycled sea spray often amounts to more than 50% of the total dry deposition of the enriched elements. Recycled sea spray also makes up a significant fraction of the total wet deposition of the enriched elements. The net deposition rates of elements such as Cu and Zn are greater than or equal to their inputs from vertical mixing, but the net deposition of Pb clearly exceeds the input from upwelling. The current net deposition rates of the enriched elements are also similar to their rates of removal to sediments. These results indicate that air-sea exchange processes may significantly affect the chemistry of trace metals in the open ocean.

  7. Five-year records of mercury wet deposition flux at GMOS sites in the Northern and Southern hemispheres

    NASA Astrophysics Data System (ADS)

    Sprovieri, Francesca; Pirrone, Nicola; Bencardino, Mariantonia; D'Amore, Francesco; Angot, Helene; Barbante, Carlo; Brunke, Ernst-Günther; Arcega-Cabrera, Flor; Cairns, Warren; Comero, Sara; Diéguez, María del Carmen; Dommergue, Aurélien; Ebinghaus, Ralf; Feng, Xin Bin; Fu, Xuewu; Garcia, Patricia Elizabeth; Gawlik, Bernd Manfred; Hageström, Ulla; Hansson, Katarina; Horvat, Milena; Kotnik, Jože; Labuschagne, Casper; Magand, Olivier; Martin, Lynwill; Mashyanov, Nikolay; Mkololo, Thumeka; Munthe, John; Obolkin, Vladimir; Ramirez Islas, Martha; Sena, Fabrizio; Somerset, Vernon; Spandow, Pia; Vardè, Massimiliano; Walters, Chavon; Wängberg, Ingvar; Weigelt, Andreas; Yang, Xu; Zhang, Hui

    2017-02-01

    The atmospheric deposition of mercury (Hg) occurs via several mechanisms, including dry and wet scavenging by precipitation events. In an effort to understand the atmospheric cycling and seasonal depositional characteristics of Hg, wet deposition samples were collected for approximately 5 years at 17 selected GMOS monitoring sites located in the Northern and Southern hemispheres in the framework of the Global Mercury Observation System (GMOS) project. Total mercury (THg) exhibited annual and seasonal patterns in Hg wet deposition samples. Interannual differences in total wet deposition are mostly linked with precipitation volume, with the greatest deposition flux occurring in the wettest years. This data set provides a new insight into baseline concentrations of THg concentrations in precipitation worldwide, particularly in regions such as the Southern Hemisphere and tropical areas where wet deposition as well as atmospheric Hg species were not investigated before, opening the way for future and additional simultaneous measurements across the GMOS network as well as new findings in future modeling studies.

  8. Wet and dry nitrogen deposition in the central Sichuan Basin of China

    NASA Astrophysics Data System (ADS)

    Kuang, Fuhong; Liu, Xuejun; Zhu, Bo; Shen, Jianlin; Pan, Yuepeng; Su, Minmin; Goulding, Keith

    2016-10-01

    Reactive nitrogen (Nr) plays a key role in the atmospheric environment and its deposition has induced large negative impacts on ecosystem health and services. Five-year continuous in-situ monitoring of N deposition, including wet (total nitrogen (WTN), total dissolved nitrogen (WTDN), dissolved organic nitrogen (WDON), ammonium nitrogen (WAN) and nitrate nitrogen (WNN)) and dry (DNH3, DHNO3, DpNH4+, DpNO3- and DNO2) deposition, had been conducted since August 2008 to December 2013 (wet) and May 2011 to December 2013 (dry) in Yan-ting, China, a typical agricultural area in the central Sichuan Basin. Mean annual total N deposition from 2011 to 2013 was 30.8 kg N ha-1 yr-1, and speculated that of 2009 and 2010 was averaged 28.2 kg N ha-1 yr-1, respectively. Wet and dry N deposition accounted for 76.3% and 23.7% of annual N deposition, respectively. Reduced N (WAN, DNH3 and DpNH4+) was 1.7 times of oxidized N (WNN, DHNO3, DNO2 and DpNO3-) which accounted for 50.9% and 30.3% of TN, respectively. Maximum loadings of all N forms of wet deposition, gaseous NH3, HNO3 and particulate NH4+ in dry deposition occurred in summer and minimum loadings in winter. Whether monthly, seasonal or annual averaged, dissolved N accounted for more than 70% of the total. N deposition in the central Sichuan Basin increased during the sampling period, especially that of ammonium compounds, and has become a serious threat to local aquatic ecosystems, the surrounding forest and other natural or semi-natural ecosystems in the upper reaches of the Yangtze River.

  9. Wet atmospheric deposition of pesticides in Minnesota, 1989-94

    USGS Publications Warehouse

    Capel, Paul D.; Lin, Ma; Wotzka, Paul J.

    1998-01-01

    The pesticide fluxes in the streams out of the small three watersheds was compared to the pesticide flux into the watersheds in rain. The data indicate that flux into the watersheds from the rain is generally much greater than the flux from the watersheds in the streams. Therefore, a large fraction of the pesticides deposited in rain is retained within the watersheds. For the urban area, this is on the order of 98 percent for the four most commonly observed herbicides in rain and runoff.

  10. Aerosol chemical vapor deposition of metal oxide films

    DOEpatents

    Ott, K.C.; Kodas, T.T.

    1994-01-11

    A process of preparing a film of a multicomponent metal oxide including: forming an aerosol from a solution comprised of a suitable solvent and at least two precursor compounds capable of volatilizing at temperatures lower than the decomposition temperature of said precursor compounds; passing said aerosol in combination with a suitable oxygen-containing carrier gas into a heated zone, said heated zone having a temperature sufficient to evaporate the solvent and volatilize said precursor compounds; and passing said volatilized precursor compounds against the surface of a substrate, said substrate having a sufficient temperature to decompose said volatilized precursor compounds whereby metal atoms contained within said volatilized precursor compounds are deposited as a metal oxide film upon the substrate is disclosed. In addition, a coated article comprising a multicomponent metal oxide film conforming to the surface of a substrate selected from the group consisting of silicon, magnesium oxide, yttrium-stabilized zirconium oxide, sapphire, or lanthanum gallate, said multicomponent metal oxide film characterized as having a substantially uniform thickness upon said substrate.

  11. The composition of wet deposition in El Paso, Texas

    NASA Astrophysics Data System (ADS)

    Emmert, Sonny

    The composition of precipitation reflects the transport of particles from varying air mass source regions as well as input from local environmental and anthropogenic activities. Air research in El Paso, TX, U.S.A/Ciudad Juarez, Chihuahua, Mexico has been traditionally limited to studies of local inputs of air pollution; no transition has been made to studying the scavenging, washout, and transport of pollutants by precipitation. The goal of this research project was to identify transported pollutants in precipitation, and determine if there were any health and ecological implications. The research investigated biological, chemical, and geological constituents in precipitation samples collected between September 2004 and October 2005. A variety of analysis techniques were used to determine composition of the precipitation. These techniques included bacterial and fungal plate counts, inductively coupled plasma/mass spectrometry, ion chromatography, transmission electron microscopy, scanning electron microscopy, and electron microprobe analysis. Samples were collected from an urban site in El Paso, Texas at the campus of the University of Texas at El Paso. Wet only samples were the target of the sample collection. Particulate matter <10 microns was correlated with fungal growth while particulate matter < 2.5 microns was correlated with bacterial growth in analyzed samples. Microscopy methods revealed new techniques in particle characterization, evidence of anthropogenic influence, and a wide variety of particle compositions. The ionic chemistry results reflected elevated levels of ions as well as an overall alkalinity of rainwater samples. Elemental analysis of the inorganic fraction suggested elevated enrichment of Phosphorus in the study area and possible ratios for transport identification of southwestern dust storms.

  12. Estimates of inorganic nitrogen wet deposition from precipitation for the conterminous United States, 1955-84

    USGS Publications Warehouse

    Gronberg, Jo Ann M.; Ludtke, Amy S.; Knifong, Donna L.

    2014-01-01

    The U.S. Geological Survey’s National Water-Quality Assessment program requires nutrient input information for analysis of national and regional assessment of water quality. Historical data are needed to lengthen the data record for assessment of trends in water quality. This report provides estimates of inorganic nitrogen deposition from precipitation for the conterminous United States for 1955–56, 1961–65, and 1981–84. The estimates were derived from ammonium, nitrate, and inorganic nitrogen concentrations in atmospheric wet deposition and precipitation-depth data. This report documents the sources of these data and the methods that were used to estimate the inorganic nitrogen deposition. Tabular datasets, including the analytical results, precipitation depth, and calculated site-specific precipitation-weighted concentrations, and raster datasets of nitrogen from wet deposition are provided as appendixes in this report.

  13. Is Erica tetralix abundance on wet heathlands controlled by nitrogen deposition or soil acidification?

    PubMed

    Damgaard, Christian; Strandberg, Morten; Kristiansen, Søren Munch; Nielsen, Knud Erik; Bak, Jesper L

    2014-01-01

    Erica tetralix is the key species on NW European wet heathlands, where it is often found to be the dominating plant species. Consequently, it is of considerable concern that the species has decreased significantly in cover from 28% to 18% over a six-year period. In order to understand the underlying causes, a structural equation modeling (SEM) approach was applied on ecological data from 1130 wet heathland plots. Both atmospheric N deposition and soil acidification were included in the SEM. The most important causal effect revealed by the SEM was a significant negative effect of N deposition on the cover of E. tetralix, whereas soil acidity tended to have a negative effect of relatively less importance. There was no significant effect of N deposition on soil pH, which indicates that there are no major indirect effects of N deposition on the cover of E. tetralix mediated by soil acidification.

  14. Source apportionment of wet-deposited atmospheric mercury in Tampa, Florida

    NASA Astrophysics Data System (ADS)

    Michael, Ryan; Stuart, Amy L.; Trotz, Maya A.; Akiwumi, Fenda

    2016-03-01

    In this paper, sources of mercury deposition to the Tampa area (Florida, USA) are investigated by analysis of one year (March 2000-March 2001) of daily wet deposition data. HYSPLIT back-trajectory modeling was performed to assess potential source locations for high versus low concentration events in data stratified by precipitation level. Positive matrix factorization (PMF) was also applied to apportion the elemental compositions from each event and to identify sources. Increased total mercury deposition was observed during summer months, corresponding to increased precipitation. However, mercury concentration in deposited samples was not strongly correlated with precipitation amount. Back-trajectories show air masses passing over Florida land in the short (12 h) and medium (24 h) term prior to deposition for high mercury concentration events. PMF results indicate that eleven factors contribute to the deposited elements in the event data. Diagnosed elemental profiles suggest the sources that contribute to mercury wet deposition at the study site are coal combustion (52% of the deposited mercury mass), municipal waste incineration (23%), medical waste incineration (19%), and crustal dust (6%). Overall, results suggest that sources local to the county and in Florida likely contributed substantially to mercury deposition at the study site, but distant sources may also contribute.

  15. Spatial distribution and source identification of wet deposition at remote EANET sites in Japan

    NASA Astrophysics Data System (ADS)

    Seto, Sinya; Sato, Manabu; Tatano, Tsutomu; Kusakari, Takashi; Hara, Hiroshi

    Wet deposition of major ions was discussed from the viewpoint of its potential sources for six remote EANET sites in Japan (Rishiri, Happo, Oki, Ogasawara, Yusuhara, and Hedo) having sufficiently high data completeness during 2000-2004. The annual deposition for each site ranged from 12.1 to 46.6 meq m -2 yr -1 for nss-SO 42-, from 5.0 to 21.9 meq m -2 yr -1 for NO 3-. The ranges of annual deposition of the two ions for the sites were lower than those for urban and rural sites in Japanese Acid Deposition Survey by Ministry of the Environment, Japan, and higher than those for global remote marine sites. Factor analysis was performed on log-transformed daily wet deposition of major ions for each site. The obtained two factors were interpreted as (1) acid and soil source (or acid source for some sites), and (2) sea-salt source for all the sites. This indicates that wet deposition of ions over the remote areas in Japan has a similar structure in terms of types of sources. Factor scores of acid and soil source were relatively high during Kosa (Asian dust) events in spring in western Japan. Back-trajectories for high-deposition episodes of acid and soil source (or acid source) for the remote sites showed that episodic air masses frequently came from the northeastern area of Asian Continent in spring and winter, and from central China in summer and autumn. This indicates a large contribution of continental emissions to wet deposition of ions over the remote areas in Japan.

  16. An Analysis of Simulated Wet Deposition of Mercury from the North American Mercury Model Intercomparison Study

    EPA Science Inventory

    A previous intercomparison of atmospheric mercury models in North America has been extended to compare simulated and observed wet deposition of mercury. Three regional-scale atmospheric mercury models were tested; CMAQ, REMSAD and TEAM. These models were each employed using thr...

  17. FUSING POINT AND AREAL LEVEL SPACE-TIME DATA WITH APPLICATION TO WET DEPOSITION

    EPA Science Inventory

    Motivated by the problem of predicting annual wet chemical deposition in the eastern United States, this paper develops a framework for joint modeling of point and grid referenced spatio-temporal data. The proposed hierarchical model is able to provide accurate spatial interpolat...

  18. Potential effects of changes in precipitation and temperature on wet deposition in central Pennsylvania

    NASA Astrophysics Data System (ADS)

    Buda, Anthony; DeWalle, David R.

    Changes in regional climate can alter conditions that control the transport, chemical transformation, and eventual deposition of atmospheric pollutants. In Pennsylvania, climate change is projected to increase mean annual temperatures by 4°C and annual precipitation amounts by about 5% through 2100. The objective of this study was to determine how increases in temperature and precipitation would affect concentrations and wet deposition of SO 42-, NO 3-, NH 4+, and H + ions at a National Atmospheric Deposition Program site (NADP, PA15) in central Pennsylvania. Event-based wet deposition data were obtained from the Multi-State Atmospheric Power Production Pollution Study (MAP3S) monitoring program for the period 1976-1989. Forward stepwise regression was used to predict log-normal concentrations per event using mean temperature, precipitation, Julian Date, and interactions of temperature and precipitation with Julian Date as predictor variables. Julian Date was included to adjust for time trends in precipitation chemistry and climate data. Results were categorized by annual periods, growing season/dormant season, and synoptic climate types. Significant positive effects of temperature on concentration and deposition were found for SO 42-, NH 4+, and H + but not for NO 3-. Precipitation increases reduced the concentration of each ion due to dilution, but the lower concentration only minimally offset the increase in wet deposition due to the increased precipitation. The effects of climate change during the growing season (April-September) were projected to cause greater increases in the magnitude of SO 42-, NO 3-, and H + concentrations and wet deposition than in the dormant season (October-March). Ammonium (NH 4+) increases were greatest during the dormant season. Climate change effects on wet deposition were generally similar among synoptic climate types with the greatest effects occurring for cold fronts and warm fronts. The impacts of climate change for this

  19. Stable nitrogen isotope ratios in wet and dry nitrate deposition collected with an artificial tree

    SciTech Connect

    Garten Jr, Charles T

    1996-02-01

    Amounts of dry NO{sub 3}-N deposition and N isotope ratios in wet and dry NO{sub 3}-N deposition have been simultaneously determined by examining differences between precipitation collected by open funnels and throughfall collected beneath an artificial Christmas tree. Samples were collected in a forest clearing on Walker Branch Watershed, near Oak Ridge, Tennessee. From mid-summer to early autumn, NO{sub 3}-N fluxes beneath the artificial tree were always greater than those measured in precipitation indicating the tree's effectiveness as a passive collector of dry NO{sub 3}-N deposition. Dry NO{sub 3}-N deposition averaged 60 {+-} 9% of total (wet and dry) deposition. The mean ({+-} SD) calculated {delta}{sup 15}N value for NO{sub 3}-N in dry deposition was + 5.6 {+-} 2.1{per_thousand} (n = 6 sampling periods ranging from 4 to 15 days). On average, this was {approx} 6{per_thousand} heavier than measured {delta}{sup 15}N values for NO{sub 3}-N in precipitation. The calculated {delta}{sup 15}N value for NO{sub 3}-N in dry deposition was consistent with that expected if NO{sub x} precursors to HNO{sub 3} vapor (the major constituent of dry deposition at this site) originated principally from coal combustion.

  20. Stable nitrogen isotope ratios in wet and dry nitrate deposition collected with an artificial tree

    NASA Astrophysics Data System (ADS)

    Garten, Charles T., Jr.

    1996-02-01

    Amounts of dry NO3-N deposition and N isotope ratios in wet and dry NO3-N deposition have been simultaneously determined by examining differences between precipitation collected by open funnels and throughfall collected beneath an artificial Christmas tree. Samples were collected in a forest clearing on Walker Branch Watershed, near Oak Ridge, Tennessee. From mid-summer to early autumn, NO3-N fluxes beneath the artificial tree were always greater than those measured in precipitation indicating the tree's effectiveness as a passive collector of dry NO3-N deposition. Dry NO3-N deposition averaged 60±9% of total (wet and dry) deposition. The mean (±SD) calculated δ15N value for NO3-N in dry deposition was+5.6±2.1‰ (n= 6 sampling periods ranging from 4 to 15days). On average, this was ≈ 6‰ heavier than measured δ15N values for NO3-N in precipitation. The calculated δ15N value for NO3-N in dry deposition was consistent with that expected if NOx precursors to HNO3 vapor (the major constituent of dry deposition at this site) originated principally from coal combustion.

  1. Temporal and spatial trends of chemical composition of wet deposition samples collected in Austria

    NASA Astrophysics Data System (ADS)

    Schreiner, Elisabeth; Kasper-Giebl, Anne; Lohninger, Hans

    2016-04-01

    Triggered by the occurrence of acid rain a sampling network for the collection of wet deposition samples was initiated in Austria in the early 1980s. Now the data set covers a time period of slightly more than 30 years for the stations being operable since the beginning. Sampling of rain water and snow was and is performed with Wet and Dry Only Samplers (WADOS) on a daily basis. Chemical analysis of rain water and snow samples comprised anions (chloride, nitrate, sulfate) and cations (sodium, ammonium, potassium, calcium and magnesium) as well as pH and electrical conductivity. Here we evaluate and discuss temporal trends of both, ion concentrations and wet deposition data for twelve sampling stations, which were operable for most of the observation period of 30 years. As expected concentrations and wet deposition loads of sulfate and acidity decreased significantly during the last three decades - which is also reflected by a strong decrease of sulfur emissions in Austria and neighboring countries. Regarding nitrate the decrease of concentrations and wet deposition loads is less pronounced. Again this is in accordance with changes in emission data. In case of ammonium even less stations showed a significant decrease of annual average concentrations and depositions. Reasons for that might be twofold. On one hand emissions of ammonia did not decrease as strongly as e.g. sulfur emissions. Furthermore local sources will be more dominant and can influence the year to year variability. Seasonality of ion concentrations and deposition loads were investigated using Fourier analysis. Sulfate, nitrate, ammonium, acidity and also precipitation amount showed characteristic seasonal patterns for most of the sites and for concentrations as well as deposition loads. However the maxima in ion concentrations and deposition loads were observed during different times of the year. Concentrations of basic cations and chloride, on the contrary, hardly showed any seasonality. However, as

  2. Wet atmospheric deposition of nitrogen: 20 years measurement in Shenzhen City, China.

    PubMed

    Huang, Yilong; Lu, XiXi; Chen, Kai

    2013-01-01

    We presented measurements of wet deposition of NH(4)(+)-N and NO(3)(-)-N from 1986 to 2006 in Shenzhen City, China. Over the past 20 years, NO(3)(-)-N concentration had significantly increased, but a reverse trend was found for NH(4)(+)-N. The main form of total inorganic nitrogen (TIN) was NH(4)(+)-N and the average NH(4)(+)-N/NO(3)(-)-N ratio was 1.57 in this area. The contribution of NO(3)(-)-N to TIN increased from 28-42% in the period of 1986-2000 to 50-63% during 2001-2006. The increased deposition flux of NO(3)(-)-N resulted in the increasing trend of TIN, although NH(4)(+)-N showed a decreasing trend over time. Average deposition flux of TIN during 1986-2006 was 13.24 kg/ha/year, with a minimum value of 6.03kg/ha/year in 1988 and a maximum value of 20.52 kg/ha/year in 1997. Wet deposition fluxes of N appeared to vary with season, 81% occurred in the warm season (from April to September). The wet deposition of TIN to the Shenzhen Reservoir reached 8,902 kg in 2006, which contributed 9.95% of the total nonpoint pollution to the reservoir and will be increased in the future.

  3. What Causes Uneven Aerosol Deposition in the Bronchoconstricted Lung? A Quantitative Imaging Study

    PubMed Central

    Greenblatt, Elliot Eliyahu; Winkler, Tilo; Harris, Robert Scott; Kelly, Vanessa Jane; Kone, Mamary; Katz, Ira; Martin, Andrew R.; Caillibotte, George

    2016-01-01

    Abstract Background: A previous PET-CT imaging study of 14 bronchoconstricted asthmatic subjects showed that peripheral aerosol deposition was highly variable among subjects and lobes. The aim of this work was to identify and quantify factors responsible for this variability. Methods: A theoretical framework was formulated to integrate four factors affecting aerosol deposition: differences in ventilation, in how air vs. aerosol distribute at each bifurcation, in the fraction of aerosol escaping feeding airways, and in the fraction of aerosol reaching the periphery that is exhaled. These factors were quantified in 12 of the subjects using PET-CT measurements of relative specific deposition sD*, relative specific ventilation sV* (measured with dynamic PET or estimated as change in expansion between two static HRCTs), average lobar expansion FVOL, and breathing frequency measured during aerosol inhalation fN. Results: The fraction of the variance of sD* explained by sV* (0.38), by bifurcation effects (0.38), and by differences in deposition along feeding airways (0.31) were similar in magnitude. We could not directly estimate the contribution of aerosol that was exhaled. Differences in expansion did not explain any fraction of the variability in sD* among lobes. The dependence of sD* on sV* was high in subjects breathing with low fN, but weakened among those breathing faster. Finally, sD*/sV* showed positive dependence on FVOL among low fN subjects, while the dependence was negative among high fN subjects. Conclusion: The theoretical framework allowed us to analyze experimentally measured aerosol deposition imaging data. When considering bronchoconstricted asthmatic subjects, a dynamic measurement of ventilation is required to evaluate its effect on aerosol transport. The mechanisms behind the identified effects of fN and FVOL on aerosol deposition need further study and may have important implications for aerosol therapy in subjects with heterogeneous ventilation

  4. Four Types of Deposits From Wet Conditions on Early Mars

    NASA Technical Reports Server (NTRS)

    2008-01-01

    Each of these four panels shows a close-up view of a different type of geological deposit formed with the involvement of water, based on observations by NASA's Mars Reconnaissance Orbiter. All four date from the earliest period of Martian history, called the Noachian Period.

    The upper-left panel shows carbonates overlying clays in the Nili Fossae region of Mars. The view combines color-coded information from infrared spectral observations by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) with an underlying black-and-white image from the High Resolution Imaging Science Experiment (HiRISE) camera. Beneath a rough-textured capping rock unit (purple) lie banded olivine-bearing layers (yellow), which in some places have been partially or wholly altered to carbonate (green).

    The upper-right panel shows phyllosilicates and chlorides in the Terra Sirenum region, observed by CRISM and HiRISE. Medium-toned, finely fractured rocks containing chloride salts either underlie higher-standing, light-toned phyllosilicates or fill in low spots between them. Both sit on dark, eroded volcanic material.

    The lower-left panel shows the upper portion of canyon wall in Coprates Chasma, observed by HiRISE and CRISM. The chasm rim cuts across the middle of the image. The wall slopes down to the top of the image and continues outside the region shown, exposing multiple phyllosilicate-bearing layers in a section of rock 7 kilometers (4 miles) thick. Two of the layers shown here are finely fractured aluminum clays that dominate the lower half of the image, underlain by thin beds of iron-magnesium clays at the top of the image. The dark material is a remnant of an overlying layer of basaltic sand that has been partly eroded away by the wind.

    The lower-right panel shows phyllosilicates with vertically layered compositions in Mawrth Vallis, observed by HiRISE (presented in enhanced color) and CRISM. The brown-colored knob in the middle of the scene is a

  5. Urbanization in China changes the composition and main sources of wet inorganic nitrogen deposition.

    PubMed

    Huang, Juan; Zhang, Wei; Zhu, Xiaomin; Gilliam, Frank S; Chen, Hao; Lu, Xiankai; Mo, Jiangming

    2015-05-01

    Nowadays, nitrogen (N) deposition has become a growing global concern due to urbanization activities increasing the large amount of reactive N in the atmosphere. However, it remains unclear whether urbanization affects the composition and main sources of N deposition in rapidly urbanizing areas such as in China. One-year measurement of wet inorganic N deposition was conducted using ion-exchange resin (IER) columns in the range of 260 km from urban to rural areas in the Pearl River Delta (PRD) region, south China. An increasing pattern of wet inorganic deposition along the urbanization gradient was observed and it increased in the order: rural (15.26 ± 0.20 kg N ha(-1) year(-1)) < suburban/rural (21.45 ± 3.73 kg N ha(-1) year(-1)) < urban (31.16 ± 0.44 kg N ha(-1) year(-1)) < urban/suburban sites (34.15 ± 5.73 kg N ha(-1) year(-1)). Nitrate N (NO3 (-)-N) accounted for 53.5-79.1 % of total wet inorganic N deposition, indicating a significant negative correlation with distance from the urban core. Based on moss δ(15)N-values the main source of NO3 (-)-N was considered to be emitted from vehicles. Our results demonstrate that urbanization has large impacts on the regional pattern of wet inorganic N deposition. Thus, controlling NOx emission, especially vehicle emission will become an effective strategy for N pollution abatement in China.

  6. Simplified data assimilation for simulating wet deposition distribution of radioactive materials in FDNPP accident

    NASA Astrophysics Data System (ADS)

    Saya, A.; Yoshikane, T.; Chang, E. C.; Yoshimura, K.

    2015-12-01

    Due to the massive earthquakes and tsunami on March 11th 2011 in Eastern Japan, Fukushima Daiichi Nuclear Power Plant (FDNPP) was severely damaged. Radioactive materials were released and spread out by atmospheric advection-diffusion. Especially on March 21 - 23th when precipitation was observed, "hotspot" where the high concentration was detected locally. This area was formed in the metropolitan area in Kanto region. Thus, pollution at water treatment plants because of the deposition became a concern. Therefore, the reliable information of the hotspot is expected. Currently, atmospheric transport simulations by numerical models are developed for reproduction of the distribution. However, there are some uncertainties in the simulations. In the case of hotspot, accuracy of simulated precipitation have to be well considered because the hotspot seemed to be formed by wet deposition. We modified the stable isotope mode of Regional Spectral Model (IsoRSM) to enable to simulate the transport of the radioactive tracers, namely 131I and 137Cs, by including the dry and wet deposition processes. As the simplified data assimilation, simulated precipitation was replaced with Radar-AMeDAS precipitation data (RAP). RAP was assimilated in the post-process, after running simulations, to redistribute wet deposition of 137Cs. The ratio of 137Cs deposited from the cumulative vertical column with precipitation in the domain was not changed, however its pattern was redistributed corresponding with RAP and simulated concentration. As a result, the redistributed wet deposition was within factor 10 to 2 compared with the fallout data in Kanto region, and further data assimilation would be contributed. In addition, we found that due to the arrival time of the plume in the morning on 21st and the border time of daily observation data of fallout, validation result might be worse even though hourly distributions are well simulated.

  7. Wet and Dry Atmospheric Mercury Deposition Accumulates in Watersheds of the Northeastern United States

    NASA Astrophysics Data System (ADS)

    Boyer, E. W.; Grant, C.; Grimm, J.; Drohan, P. J.; Bennett, J.; Lawler, D.

    2013-12-01

    Mercury emissions to the atmosphere from coal-fired power plants and other sources such as waste incineration can be deposited to landscapes in precipitation and in dry fallout. Some mercury reaches watersheds and streams, where it can accumulate in sediments and biota. Human exposure to mercury occurs primarily through fish consumption, and currently mercury fish eating advisories are in place for many of the streams and lakes in the state. Here, we explored mercury in air, soils, water, and biota. To quantify atmospheric mercury deposition, we measured both wet and dry mercury deposition at over 10 locations in Pennsylvania, from which we present variation in mercury deposition and initial assessments of factors affecting the patterns. Further, we simulated mercury deposition at unmonitored locations in Pennsylvania and the northeastern United States over space and time with a high-resolution modeling technique that reflects storm tracks and air flow patterns. To consider mercury accumulation in watersheds, we collected data on soil mercury concentrations in a set of soil samples, and collected baseline data on mercury in streams draining 35 forested watersheds across Pennsylvania, spanning gradients of atmospheric deposition, climate and geology. Mercury concentrations were measured in stream water under base-flow conditions, in streambed sediments, aquatic mosses, and in fish tissues from brook trout. Results indicate that wet and dry atmospheric deposition is a primary source of mercury that is accumulating in watersheds of Pennsylvania and the northeastern United States.

  8. Sulfate-rich eolian and wet interdune deposits, erebus crater, meridiani Planum, Mars

    USGS Publications Warehouse

    Metz, J.M.; Grotzinger, J.P.; Rubin, D.M.; Lewis, K.W.; Squyres, S. W.; Bell, J.F.

    2009-01-01

    This study investigates three bedrock exposures at Erebus crater, an ?? 300 m diameter crater approximately 4 km south of Endurance crater on Mars. These outcrops, called Olympia, Payson, and Yavapai, provide additional evidence in support of the dune-interdune model proposed for the formation of the deposits at the Opportunity landing site in Meridiani Planum. There is evidence for greater involvement of liquid water in the Olympia outcrop exposures than was observed in Eagle or Endurance craters. The Olympia outcrop likely formed in a wet interdune and sand sheet environment. The facies observed within the Payson outcrop, which is likely stratigraphically above the Olympia outcrop, indicate that it was deposited in a damp-wet interdune, sand sheet, and eolian dune environment. The Yavapai outcrop, which likely stratigraphically overlies the Payson outcrop, indicates that it was deposited in primarily a sand sheet environment and also potentially in an eolian dune environment. These three outcrop exposures may indicate an overall drying-upward trend spanning the stratigraphic section from its base at the Olympia outcrop to its top at the Yavapai outcrop. This contrasts with the wetting-upward trend seen in Endurance and Eagle craters. Thus, the series of outcrops seen at Meridiani by Opportunity may constitute a full climatic cycle, evolving from dry to wet to dry conditions. ?? 2009, SEPM (Society for Sedimentary Geology).

  9. Modelling wet deposition in simulations of volcanic ash dispersion from hypothetical eruptions of Merapi, Indonesia

    NASA Astrophysics Data System (ADS)

    Dare, Richard A.; Potts, Rodney J.; Wain, Alan G.

    2016-10-01

    The statistical impact of including the process of wet deposition in dispersion model predictions of the movement of volcanic ash is assessed. Based on hypothetical eruptions of Merapi, Indonesia, sets of dispersion model simulations were generated, each containing four simulations per day over a period of three years, to provide results based on a wide range of atmospheric conditions. While on average dry sedimentation removes approximately 10% of the volcanic ash from the atmosphere during the first 24 h, wet deposition removes an additional 30% during seasons with highest rainfall (December and January) but only an additional 1% during August and September. The majority of the wet removal is due to in-cloud rather than below-cloud collection of volcanic ash particles. The largest uncertainties in the amount of volcanic ash removed by the process of wet deposition result from the choice of user-defined parameters used to compute the scavenging coefficient, and from the definition of the cloud top height. Errors in the precipitation field provided by the numerical weather prediction model utilised here have relatively less impact.

  10. Phase-contrast helium-3 MRI of aerosol deposition in human airways.

    PubMed

    Sarracanie, Mathieu; Grebenkov, Denis; Sandeau, Julien; Coulibaly, Soulé; Martin, Andrew R; Hill, Kyle; Pérez Sánchez, José Manuel; Fodil, Redouane; Martin, Lionel; Durand, Emmanuel; Caillibotte, Georges; Isabey, Daniel; Darrasse, Luc; Bittoun, Jacques; Maître, Xavier

    2015-02-01

    One of the key challenges in the study of health-related aerosols is predicting and monitoring sites of particle deposition in the respiratory tract. The potential health risks of ambient exposure to environmental or workplace aerosols and the beneficial effects of medical aerosols are strongly influenced by the site of aerosol deposition along the respiratory tract. Nuclear medicine is the only current modality that combines quantification and regional localization of aerosol deposition, and this technique remains limited by its spatial and temporal resolutions and by patient exposure to radiation. Recent work in MRI has shed light on techniques to quantify micro-sized magnetic particles in living bodies by the measurement of associated static magnetic field variations. With regard to lung MRI, hyperpolarized helium-3 may be used as a tracer gas to compensate for the lack of MR signal in the airways, so as to allow assessment of pulmonary function and morphology. The extrathoracic region of the human respiratory system plays a critical role in determining aerosol deposition patterns, as it acts as a filter upstream from the lungs. In the present work, aerosol deposition in a mouth-throat phantom was measured using helium-3 MRI and compared with single-photon emission computed tomography. By providing high sensitivity with high spatial and temporal resolutions, phase-contrast helium-3 MRI offers new insights for the study of particle transport and deposition.

  11. Research of transport and deposition of aerosol in human airway replica

    NASA Astrophysics Data System (ADS)

    Lizal, Frantisek; Jedelsky, Jan; Elcner, Jakub; Durdina, Lukas; Halasova, Tereza; Mravec, Filip; Jicha, Miroslav

    2012-04-01

    Growing concern about knowledge of aerosol transport in human lungs is caused by great potential of use of inhaled pharmaceuticals. Second substantial motive for the research is an effort to minimize adverse effects of particular matter emitted by traffic and industry on human health. We created model geometry of human lungs to 7th generation of branching. This model geometry was used for fabrication of two physical models. The first one is made from thin walled transparent silicone and it allows a measurement of velocity and size of aerosol particles by Phase Doppler Anemometry (PDA). The second one is fabricated by stereolithographic method and it is designed for aerosol deposition measurements. We provided a series of measurements of aerosol transport in the transparent model and we ascertained remarkable phenomena linked with lung flow. The results are presented in brief. To gather how this phenomena affects aerosol deposition in human lungs we used the second model and we developed a technique for deposition fraction and deposition efficiency assessment. The results confirmed that non-symmetric and complicated shape of human airways essentially affects transport and deposition of aerosol. The research will now focus on deeper insight in aerosol deposition.

  12. Impact of wet scavenging of natural and anthropogenic aerosol components on the columnar aerosol optical depth over a tropical rural atmosphere

    NASA Astrophysics Data System (ADS)

    Chatterjee, Abhijit; Jayaraman, Achuthan

    A typical feature of Indian monsoon is that, several dry days are observed even between the rain events. Atmospheric aerosol shows significant variations in their concentration between "before" and "after" the rain because of their efficient scavenging during the rain. The below cloud scavenging of several aerosol components during the rain has a direct impact on the columnar aerosol optical depth (AOD) between "before" and "after" the rain. In order to investigate the impact of the scavenging of several natural and anthropogenic aerosol components on spectral properties of aerosol, simultaneous studies on the characterization of aerosol, rainwater and AOD were done during July-December 2009 over a tropical rural atmosphere at Gadanki (13.5 0N, 79.2 0E) in southern peninsular India. Aerosols were collected and analyzed before, during and after the rain along with the collection and analysis of rainwater in several rain events during the entire study period. AOD data (at wavelengths of 400, 500, 675, 870, 1020 nm) was retrieved by processing the data obtained from an automatic sunphotomer (PREDE, PM 01) using the standard SKYRAD pack. Aerosols and rainwater samples were analyzed for water soluble ionic species using an Ion Chromatograph (Metrohm, 861). We observed that aerosols were highly loaded in the atmosphere just before the rain, efficiently scavenged during the rain and built-up slowly after the rain. Interestingly, the loading of sulphate aerosol after the rain was remarkably high whereas that of calcium and magnesium were remarkably low. The poor resuspension of soil dust from the wet soils after the rain could not allow calcium and magnesium to be loaded in the atmosphere whereas the high relative humidity favored the gas-to-particle conversion of SO2 to SO42-which allowed the high loading of sulphate aerosol in the atmosphere. Significant reductions in AOD both at lower (400 nm) and higher wavelength (1020 nm) were observed after the rain events. Two

  13. Determining the basic characteristics of aerosols suitable for studies of deposition in the respiratory tract.

    PubMed

    Legáth, L; Naus, A; Halík, J

    1988-01-01

    Studies of aerosol particle deposition in the respiratory tract requires experimental inhalation of artificial model aerosols. The paper formulates some of the most important requirements for the properties of such aerosols. Several suitable fractions were prepared as part of a research project dealing with the use of microporous polymers for diagnostic purposes. 5 fractions of the polymer designated G-gel 60 with the particle size as stated by the manufacturer, ranging from 3 to 7 micron were evaluated using a 16-channel particle dispersity analyzer HIAC/ROYCO MT 3210 with the sensor 1200 and operated by a microprocessor, the equipment being coupled to an APPLE IIe computer. G-gel 60 particles introduced into the aerosol were characterized by the parameters CMAD, MMAD and sg both numerically and graphically. The measurement procedure was found to be very sensitive with respect to all fractions in evaluating the subtile differences between different lot numbers of the aerosol. G-gel 60 fractions characterized both numerically and graphically were compared with the known aerosols from paraffin oil and atmospheric air. The equipment MT 3210 enables prompt determination of the percentages of aerosol particles distribution by size class. The authors conclude that the procedure, both in its numerical and graphical versions, is particularly suitable for the diagnosis of aerosol particles deposition in the respiratory tract, offering a new application for HIAC/ROYCO in the field of medicine. In evaluating atmospheric aerosol in exhaled air, the number of particles was found to be below that in inhaled air, the difference being dependent on the choice of investigation methods. Percentual distribution of deposited particles following one minute ventilation proved to be at its maximum, as regards atmospheric aerosol, in the 0.30-0.50 micron range. The deposition curve was similar to already published curves, being characterized by an S-shaped pattern with maximum deposition

  14. Effects of surface-active organic matter on carbon dioxide nucleation in atmospheric wet aerosols: a molecular dynamics study.

    PubMed

    Daskalakis, Vangelis; Charalambous, Fevronia; Panagiotou, Fostira; Nearchou, Irene

    2014-11-21

    Organic matter (OM) uptake in cloud droplets produces water-soluble secondary organic aerosols (SOA) via aqueous chemistry. These play a significant role in aerosol properties. We report the effects of OM uptake in wet aerosols, in terms of the dissolved-to-gas carbon dioxide nucleation using molecular dynamics (MD) simulations. Carbon dioxide has been implicated in the natural rainwater as well as seawater acidity. Variability of the cloud and raindrop pH is assumed in space and time, as regional emissions, local human activities and geophysical characteristics differ. Rain scavenging of inorganic SOx, NOx and NH3 plays a major role in rain acidity in terms of acid-base activity, however carbon dioxide solubility also remains a key parameter. Based on the MD simulations we propose that the presence of surface-active OM promotes the dissolved-to-gas carbon dioxide nucleation in wet aerosols, even at low temperatures, strongly decreasing carbon dioxide solubility. A discussion is made on the role of OM in controlling the pH of a cloud or raindrop, as a consequence, without involving OM ionization equilibrium. The results are compared with experimental and computational studies in the literature.

  15. Wet and Dry Atmospheric Depositions of Inorganic Nitrogen during Plant Growing Season in the Coastal Zone of Yellow River Delta

    PubMed Central

    Li, Yunzhao; Du, Siyao; Han, Guangxuan; Xing, Qinghui; Wu, Huifeng; Wang, Guangmei

    2014-01-01

    The ecological problems caused by dry and wet deposition of atmospheric nitrogen have been widespread concern in the world. In this study, wet and dry atmospheric depositions were monitored in plant growing season in the coastal zone of the Yellow River Delta (YRD) using automatic sampling equipment. The results showed that SO42− and Na+ were the predominant anion and cation, respectively, in both wet and dry atmospheric depositions. The total atmospheric nitrogen deposition was ~2264.24 mg m−2, in which dry atmospheric nitrogen deposition was about 32.02%. The highest values of dry and wet atmospheric nitrogen deposition appeared in May and August, respectively. In the studied area, NO3−–N was the main nitrogen form in dry deposition, while the predominant nitrogen in wet atmospheric deposition was NH4+–N with ~56.51% of total wet atmospheric nitrogen deposition. The average monthly attribution rate of atmospheric deposition of NO3−–N and NH4+–N was ~31.38% and ~20.50% for the contents of NO3−–N and NH4+–N in 0–10 cm soil layer, respectively, suggested that the atmospheric nitrogen was one of main sources for soil nitrogen in coastal zone of the YRD. PMID:24977238

  16. Wet and dry atmospheric depositions of inorganic nitrogen during plant growing season in the coastal zone of Yellow River Delta.

    PubMed

    Yu, Junbao; Ning, Kai; Li, Yunzhao; Du, Siyao; Han, Guangxuan; Xing, Qinghui; Wu, Huifeng; Wang, Guangmei; Gao, Yongjun

    2014-01-01

    The ecological problems caused by dry and wet deposition of atmospheric nitrogen have been widespread concern in the world. In this study, wet and dry atmospheric depositions were monitored in plant growing season in the coastal zone of the Yellow River Delta (YRD) using automatic sampling equipment. The results showed that SO4 (2-) and Na(+) were the predominant anion and cation, respectively, in both wet and dry atmospheric depositions. The total atmospheric nitrogen deposition was ~2264.24 mg m(-2), in which dry atmospheric nitrogen deposition was about 32.02%. The highest values of dry and wet atmospheric nitrogen deposition appeared in May and August, respectively. In the studied area, NO3 (-)-N was the main nitrogen form in dry deposition, while the predominant nitrogen in wet atmospheric deposition was NH4 (+)-N with ~56.51% of total wet atmospheric nitrogen deposition. The average monthly attribution rate of atmospheric deposition of NO3 (-)-N and NH4 (+)-N was ~31.38% and ~20.50% for the contents of NO3 (-)-N and NH4 (+)-N in 0-10 cm soil layer, respectively, suggested that the atmospheric nitrogen was one of main sources for soil nitrogen in coastal zone of the YRD.

  17. 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.

  18. COMPARISON OF MONODISPERSE AND POLYDISPERSE AEROSOL DEPOSITION IN A PACKED BED

    EPA Science Inventory

    COMPARISON OF MONODISPERSE AND POLYDISPERSE AEROSOL DEPOSITION IN A PACKED BED. Jacky A. Rosati, Dept. of Environmental Sciences and Engineering, University of North Carolina, Chapel Hill, NC 27599; Chong S. Kim, USEPA National Health and Environmental Effects Research Laboratory...

  19. Four-year record of mercury wet deposition in one typical industrial city in southwest China

    NASA Astrophysics Data System (ADS)

    Qin, Caiqing; Wang, Yongmin; Peng, Yulong; Wang, Dingyong

    2016-10-01

    During the period from December 2010 to November 2014, long-term monitoring of Hg wet deposition was conducted at three sites in Chongqing. The four-year volume-weighted mean concentrations (VWC) of total mercury (THg) and methylmercury (MeHg) in precipitation were 34.25 ng L-1 and 0.48 ng L-1, respectively. The average annual wet deposition fluxes were 37.83 ± 11.53 μg m-2 yr-1 for THg and 0.61 ± 0.19 μg m-2 yr-1 for MeHg. Besides, the average proportion of MeHg in THg was 1.41%. These data were well ahead of values observed in most of other areas. The annual VWC of Hg rose remarkably in 2012 and then reached a plateau or climbed mildly in the following 2 years, while its annual wet deposition fluxes saw an upward trend throughout the whole period. In addition, the high figures of Hg concentration were generally found in the non-monsoon seasons, but its elevated wet deposition fluxes normally appeared in the rainy seasons. These characteristics of inter-annual and seasonal changes for VWC and fluxes were observed at every sampling site in this study as well. Besides, there were significantly spatial distributions for VWC and fluxes of THg in the descending order of the downtown (NA), the suburban (BB) and the controlled site (JY). While for MeHg, BB had the largest values, followed by NA and JY. So apart from THg load, the formation of MeHg was influenced by other factors in Chongqing, like the concentration of reactive mercury (RHg) in precipitation. Additionally, particulate bound mercury (PHg) is the dominant form among various Hg species, and atmospheric Hg is effectively eliminated during the initial period of the rain event and the below-cloud scavenging is the predominant mechanism contributing Hg to precipitation.

  20. Source attribution, physicochemical properties and spatial distribution of wet deposited mercury to the Ohio River valley

    NASA Astrophysics Data System (ADS)

    White, Emily Mae

    Mercury (Hg) is a bioaccumulative neurotoxin that is emitted from anthropogenic sources through fossil fuel combustion. The spatial scale of atmospheric transport prior to deposition is dependent on the chemical and physical form of Hg emissions, and has yet to be quantitatively defined. A five-year comprehensive Hg monitoring and source apportionment study was conducted in Steubenville, Ohio to investigate atmospheric Hg deposition to the highly industrialized Ohio River Valley region. Long-term event-precipitation measurements revealed a significant 30% to three-fold enrichment of Hg concentrations and total Hg deposition flux to the Steubenville site over other Great Lakes regional sites. Multivariate receptor models attributed ˜70% of Hg wet deposition to local coal combustion sources. While local stagnant atmospheric conditions led to moderately high volume-weighted mean Hg concentrations and the majority of Hg wet deposition flux, regional transport from the Chicago/Gary and Detroit/Windsor urban areas also led to elevated precipitation Hg concentrations, but did not contribute significantly to the overall Hg deposition. The degree of local source influence was established during a summertime field intensive study in which a local scale network of concurrently collected rain samples revealed that 42% of Hg wet deposition measured less than one km from the base of coal fired utilities could be attributed to the adjacent source, corresponding to 170% Hg concentration enhancement over regionally representative precipitation collected concurrently. In addition, 69+/-37% of the Hg collected in rain was in a soluble form, entering the precipitation as reactive gas phase or fine particle associated Hg. The Hg scavenging coefficient (rate of concentration reduction throughout a single precipitation event) was particularly low when compared to other trace elements. Furthermore, when compared to an upwind but non-locally source impacted site, the scavenging

  1. Wet deposition of mercury at a remote site in the Tibetan Plateau: Concentrations, speciation, and fluxes

    NASA Astrophysics Data System (ADS)

    Huang, Jie; Kang, Shichang; Zhang, Qianggong; Yan, Haiyu; Guo, Junming; Jenkins, Matt G.; Zhang, Guoshuai; Wang, Kang

    2012-12-01

    Precipitation samples collected at a remote high elevation site (i.e., Nam Co Station, 4730 m a.s.l.) in the southern Tibetan Plateau were analyzed for total mercury (HgT) between July 2009 and 2011, particulate-bound mercury (HgP) between July 2010 and 2011 and methylmercury (MeHg) from July through August of 2009. The volume-weighted mean (VWM) concentrations and wet deposition fluxes of HgT and MeHg in precipitation were 4.8 ng L-1 and 1.75 μg m-2 yr-1, 0.031 ng L-1 and 0.01 μg m-2 yr-1, respectively. VWM HgT concentration was approximately two times higher during the non-monsoon season than during the monsoon season, while 83% of the HgT wet deposition fluxes occurred during the monsoon season. The HgT and MeHg concentrations are comparable to the reported data for some of the most remote alpine and polar regions worldwide (e.g., Churchill), but the wet deposition fluxes of HgT and MeHg were among the lowest in the world. Analysis of Hg speciation has presented that HgP and MeHg concentrations are high, making up 71.2% and 1.82% of the HgT on average (VWM), respectively. The high HgP%, as well as a significantly positive between HgT and HgP (R2 = 0.91; n = 44; p < 0.001), confirmed that atmospheric deposition of Hg in the Tibetan Plateau was occurring in the form of HgP. A decreasing trend in HgT concentrations with increasing amount of precipitation (R2 = 0.08; N = 101; p < 0.005) was found at Nam Co Station, indicative that scavenging of HgP from the atmosphere was an important mechanism contributing Hg to precipitation. The precipitation amount, rather than HgT concentration, was found to be the governing factor affecting HgT wet deposition flux. Moreover, a comparison between measured wet deposition flux of Hg at Nam Co Station and the estimates from environmental records indicated that both snowpits and lake sediments appear to be reliable archives for estimating historical Hg accumulation rates over the Tibetan Plateau.

  2. Influence of anthropogenic aerosol deposition on the relationship between oceanic productivity and warming

    NASA Astrophysics Data System (ADS)

    Wang, Rong; Balkanski, Yves; Bopp, Laurent; Aumont, Olivier; Boucher, Olivier; Ciais, Philippe; Gehlen, Marion; Peñuelas, Josep; Ethé, Christian; Hauglustaine, Didier; Li, Bengang; Liu, Junfeng; Zhou, Feng; Tao, Shu

    2015-12-01

    Satellite data and models suggest that oceanic productivity is reduced in response to less nutrient supply under warming. In contrast, anthropogenic aerosols provide nutrients and exert a fertilizing effect, but its contribution to evolution of oceanic productivity is unknown. We simulate the response of oceanic biogeochemistry to anthropogenic aerosols deposition under varying climate from 1850 to 2010. We find a positive response of observed chlorophyll to deposition of anthropogenic aerosols. Our results suggest that anthropogenic aerosols reduce the sensitivity of oceanic productivity to warming from -15.2 ± 1.8 to -13.3 ± 1.6 Pg C yr-1 °C-1 in global stratified oceans during 1948-2007. The reducing percentage over the North Atlantic, North Pacific, and Indian Oceans reaches 40, 24, and 25%, respectively. We hypothesize that inevitable reduction of aerosol emissions in response to higher air quality standards in the future might accelerate the decline of oceanic productivity per unit warming.

  3. Aerosol transport and wet scavenging in deep convective clouds: A case study and model evaluation using a multiple passive tracer analysis approach

    NASA Astrophysics Data System (ADS)

    Yang, Qing; Easter, Richard C.; Campuzano-Jost, Pedro; Jimenez, Jose L.; Fast, Jerome D.; Ghan, Steven J.; Wang, Hailong; Berg, Larry K.; Barth, Mary C.; Liu, Ying; Shrivastava, Manishkumar B.; Singh, Balwinder; Morrison, Hugh; Fan, Jiwen; Ziegler, Conrad L.; Bela, Megan; Apel, Eric; Diskin, Glenn S.; Mikoviny, Tomas; Wisthaler, Armin

    2015-08-01

    Wet scavenging of aerosols by continental deep convective clouds is studied for a supercell storm complex observed over Oklahoma during the Deep Convective Clouds and Chemistry campaign. A new passive-tracer-based transport analysis framework is developed to characterize convective transport using vertical profiles of several passive trace gases. For this case, the analysis estimates that observed passive gas mixing ratios in the upper troposphere convective outflow consist of 47% low level (<3 km) inflow air, 32% entrained midtroposphere air, and 21% upper troposphere air. The new analysis framework is used to estimate aerosol wet scavenging efficiencies. Observations yield high overall scavenging efficiencies of 81% for submicron aerosol mass. Organic, sulfate, and ammonium aerosols have similar wet scavenging efficiencies (80%-84%). The apparent scavenging efficiency for nitrate aerosol is much lower (57%), but the scavenging efficiency for nitrate aerosol plus nitric acid combined (84%) is close to the other species. Scavenging efficiencies for aerosol number are high for larger particles (84% for 0.15-2.5 µm diameter) but are lower for smaller particles (64% for 0.03-0.15 µm). The storm is simulated using the chemistry version of the Weather Research and Forecasting model. Compared to the observation-based analysis, the standard model strongly underestimates aerosol scavenging efficiencies by 32% and 41% in absolute differences for submicron mass and number. Adding a new treatment of secondary activation significantly improves simulated aerosol scavenging, producing wet scavenging efficiencies that are only 7% and 8% lower than observed efficiencies. This finding emphasizes the importance of secondary activation for aerosol wet removal in deep convective storms.

  4. Development of a sampler for total aerosol deposition in the human respiratory tract.

    PubMed

    Koehler, Kirsten A; Clark, Phillip; Volckens, John

    2009-10-01

    Studies that seek to associate reduced human health with exposure to occupational and environmental aerosols are often hampered by limitations in the exposure assessment process. One limitation involves the measured exposure metric itself. Current methods for personal exposure assessment are designed to estimate the aspiration of aerosol into the human body. Since a large proportion of inhaled aerosol is subsequently exhaled, a portion of the aspirated aerosol will not contribute to the dose. This leads to variable exposure misclassification (for heterogenous exposures) and increased uncertainty in health effect associations. Alternatively, a metric for respiratory deposition would provide a more physiologically relevant estimate of risk. To address this challenge, we have developed a method to estimate the deposition of aerosol in the human respiratory tract using a sampler engineered from polyurethane foam. Using a semi-empirical model based on inertial, gravitational, and diffusional particle deposition, a foam was engineered to mimic aerosol total deposition in the human respiratory tract. The sampler is comprised of commercially available foam with fiber diameter = 49.5 microm (equivalent to industry standard 100 PPI foam) of 8 cm thickness operating at a face velocity of 1.3 m s(-1). Additionally, the foam sampler yields a relatively low-pressure drop, independent of aerosol loading, providing uniform particle collection efficiency over time.

  5. Temporal and spatial patterns in the chemistry of wet deposition in Southern Alps

    NASA Astrophysics Data System (ADS)

    Rogora, M.; Colombo, L.; Marchetto, A.; Mosello, R.; Steingruber, S.

    2016-12-01

    In the last decades, in Europe a large effort was carried out to reduce sulphur and nitrogen emission in the atmosphere, in order to improve air quality and reduce the acidity of atmospheric deposition and the amount of nitrogen compounds it carries to terrestrial and aquatic ecosystems. This resulted in a sharp decrease in the deposition of sulphate and acidity, while until recently a decrease of the atmospheric load of nitrogen compounds was not evident. In this paper, we focus on the subalpine and alpine areas in North-Western Italy and Southern Switzerland (Canton Ticino), receiving high deposition of atmospheric pollutants transported from emission sources in the Po Valley, one of the most urbanised and industrialised areas of Europe. Long-term studies, covering a 30-year period (1984-2014), were carried out on the chemistry of atmospheric deposition in this area and its effects on surface water bodies through a cooperation between Swiss and Italian research institutions. A total of 14 atmospheric deposition wet-only sampling sites operate in this area, covering a wide latitudinal and altitudinal range (about 200-1900 m a.s.l.). A spatial gradient in the deposition of sulphate and nitrogen compounds was evident both in the 1990s and in recent times (2008-2012), with highest values in the south-eastern part of the area, close to the major emission sources. Deposition also varied depending on local topography. The analysis of long-term trends revealed a large proportion of significant decreasing trends in the concentration of both sulphate and nitrogen compounds. Deposition changes were less evident, due to the high interannual variability in the data, caused by the highly variable precipitation amount, ranging from 1200-1300 mm in dry years to 3000 mm in wet years. Sulphate concentrations and deposition decreased steadily since the 1980s, while ammonium and nitrate showed a widespread decrease only in the most recent period (after 2006). However, nitrogen wet

  6. Comparison of snowpack and winter wet-deposition chemistry in the Rocky Mountains, USA: Implications for winter dry deposition

    USGS Publications Warehouse

    Clow, David W.; Ingersoll, George P.; Mast, M. Alisa; Turk, John T.; Campbell, Donald H.

    2002-01-01

    Depth-integrated snowpack chemistry was measured just prior to maximum snowpack depth during the winters of 1992-1999 at 12 sites co-located with National Atmospheric Deposition Program/National Trend Network (NADP/NTN) sites in the central and southern Rocky Mountains, USA. Winter volume-weighted mean wet-deposition concentrations were calculated for the NADP/NTN sites, and the data were compared to snowpack concentrations using the paired t-test and the Wilcoxon signed-rank test. No statistically significant differences were indicated in concentrations of SO42- or NO3- (p>0.1). Small, but statistically significant differences (p???0.03) were indicated for all other solutes analyzed. Differences were largest for Ca2+ concentrations, which on average were 2.3??eql-1 (43%) higher in the snowpack than in winter NADP/NTN samples. Eolian carbonate dust appeared to influence snowpack chemistry through both wet and dry deposition, and the effect increased from north to south. Dry deposition of eolian carbonates was estimated to have neutralized an average of 6.9??eql-1 and a maximum of 12??eql-1 of snowpack acidity at the southernmost sites. The good agreement between snowpack and winter NADP/NTN SO42- and NO3- concentrations indicates that for those solutes the two data sets can be combined to increase data density in high-elevation areas, where few NADP/NTN sites exist. This combination of data sets will allow for better estimates of atmospheric deposition of SO42- and NO3- across the Rocky Mountain region.

  7. Recent advances in the development of a novel aerosol sorting and deposition system for bio-threat sensing applications

    NASA Astrophysics Data System (ADS)

    Pletcher, Timothy; McGinn, Joseph; Keller, David; Huston, Alan; Eversole, Jay; Sivaprakasum, Vasanthi

    2007-10-01

    Sarnoff Corporation and the Naval Research Laboratory, through support of the U.S. Department of Homeland Security, are developing an automated, high throughput bio-aerosol physical enrichment system designed for use as part of a biological-threat protection system. The Biological Aerosol-Capture-Enrichment (BioACE) system is a bio-aerosol collection system that combines three unique technologies to create physically enriched aerosol samples that can be subsequently interrogated by any number of bio-threat detection systems for the presence of threat agents. An air-to-air concentrator uses an inertial separation technique to highly concentrate an aerosol sample presented to a dual wavelength ultra-violet laser induced fluorescence (UVLIF) optical trigger used to discriminate potential threat particles from non-threat particles conveyed in a collimated particle stream. This particle classification information is used to trigger an electrostatic deposition mechanism to deposit only those particles determined to be potential bio-threats onto a stainless steel substrate. Non-threat particles are discarded with the exiting airflow. The goal for the most recent development effort has been the integration and optimization of these technologies into a unit capable of producing highly enriched particulate samples from ambient air containing variable background aerosol loading and type. Several key technical and engineering challenges were overcome during the course of this development including a unique solution for compensating particle velocity dispersion within the airflow, development of a real-time signal acquisition and detection algorithm for determining material type on a particle by particle basis at rates greater than 2000 particles per second, and the introduction of a robust method for transferring deposited particulate into a 50ul wet sample suitable for most advanced bio-detection techniques. This paper will briefly describe the overall system architecture and

  8. Controlling Factors of Long-Term Trends in Mercury Wet Deposition and Precipitation Concentrations at Huntington Wildlife Forest

    NASA Astrophysics Data System (ADS)

    Ye, Z.; Mao, H.; Driscoll, C. T.

    2015-12-01

    Observations from the Mercury Deposition Network (MDN) at Huntington Wildlife Forest (HWF) suggested that a significant decline (r2 = 0.34, p = 0.03) from 2000 to 2013 in volume weighted mean (VWM) Hg concentrations in precipitation was linked to Hg emission decreases in the United States, especially in the Northeast and Midwest, and yet Hg wet deposition has remained fairly constant over the past two decades. The present study aimed to investigate the climatic, terrestrial, and anthropogenic factors that influenced the decadal pattern in Hg wet deposition in upstate NY. In spring and summer, when Hg wet deposition was the strongest, significant positive correlation (r2 = 0.89, p < 0.0001 in spring; r2 = 0.58, p = 0.002 in summer) of Hg wet deposition with precipitation was found. Increases in precipitation during these seasons could offset the decreasing of Hg concentration in precipitation. Besides, springtime positive correlation (r2 = 0.35, p = 0.02) between precipitation and the North Atlantic Oscillation (NAO) index together with geopotential height and wind speed analysis indicated that large-scale dynamical forcing was likely an important factor influencing the long term trend in springtime Hg wet deposition at HWF. To further quantify the roles of meteorological and anthropogenic factors in Hg wet deposition, the Community Multiscale Air Quality (CMAQ) model was employed using an algorithm depicting state-of-the-art Hg chemistry mechanism and up-to-date Hg emission inventories evaluated with MDN and Atmospheric Mercury Network (AMNet) measurement data. CMAQ simulations with a constant vs. realistic meteorological conditions for multiple warm seasons (including spring and summer) were used to characterize and quantify the impacts of inter-annual variability of precipitation and atmospheric circulation on Hg wet deposition. In addition, contributions to Hg wet deposition from decreases in anthropogenic emissions in NYS and nation-wide were quantified from

  9. Sensitivity study of the wet deposition schemes in the modelling of the Fukushima accident.

    NASA Astrophysics Data System (ADS)

    Quérel, Arnaud; Quélo, Denis; Roustan, Yelva; Mathieu, Anne; Kajino, Mizuo; Sekiyama, Thomas; Adachi, Kouji; Didier, Damien; Igarashi, Yasuhito

    2016-04-01

    The Fukushima-Daiichi release of radioactivity is a relevant event to study the atmospheric dispersion modelling of radionuclides. Actually, the atmospheric deposition onto the ground may be studied through the map of measured Cs-137 established consecutively to the accident. The limits of detection were low enough to make the measurements possible as far as 250km from the nuclear power plant. This large scale deposition has been modelled with the Eulerian model ldX. However, several weeks of emissions in multiple weather conditions make it a real challenge. Besides, these measurements are accumulated deposition of Cs-137 over the whole period and do not inform of deposition mechanisms involved: in-cloud, below-cloud, dry deposition. A comprehensive sensitivity analysis is performed in order to understand wet deposition mechanisms. It has been shown in a previous study (Quérel et al, 2016) that the choice of the wet deposition scheme has a strong impact on the assessment of the deposition patterns. Nevertheless, a "best" scheme could not be highlighted as it depends on the selected criteria: the ranking differs according to the statistical indicators considered (correlation, figure of merit in space and factor 2). A possibility to explain the difficulty to discriminate between several schemes was the uncertainties in the modelling, resulting from the meteorological data for instance. Since the move of the plume is not properly modelled, the deposition processes are applied with an inaccurate activity in the air. In the framework of the SAKURA project, an MRI-IRSN collaboration, new meteorological fields at higher resolution (Sekiyama et al., 2013) were provided and allows to reconsider the previous study. An updated study including these new meteorology data is presented. In addition, a focus on several releases causing deposition in located areas during known period was done. This helps to better understand the mechanisms of deposition involved following the

  10. Hydrogen content of underwater wet welds deposited by rutile and oxidizing electrodes

    SciTech Connect

    Pope, A.M.; Liu, S.

    1996-12-01

    Shielded metal arc wet welding, due to its flexibility and ease of mobilization, is one of the most attractive methods for repair of underwater structures. However, the quality of the weld metals deposited by this process is detrimentally affected by the direct contact of the welding arc with the aqueous environment. Oxygen and hydrogen generated by the decomposition of water in the arc are responsible for the main problems related to this specific process: loss of deoxidizers, oxygen pickup, increase in oxide inclusions content, hydrogen-induced cracking, and porosity. Rutile electrodes are recognized in the literature as being able to deposit welds with adequate mechanical properties but with high hydrogen content. Oxidizing electrodes, on the other hand, are able to deposit welds with lower hydrogen content but higher oxygen content. Welds deposited by rutile electrodes presented approximately 90 ml/100g of diffusible hydrogen while oxidizing electrodes produced welds with diffusible hydrogen contents varying from 40 to 50 ml/100g. It was found that the measured diffusible hydrogen contents of underwater wet welds are more dependent on the type of electrode covering than on the weld metal oxygen content. The residual hydrogen content of underwater welds showed a tendency to increase to a constant level of approximately 5 ml/100g as the oxygen content of the weld increased to the saturation value (0.22 wt.pct.). It seems, therefore, that the diffusible hydrogen content of underwater wet welds is more influenced by the amount of total hydrogen absorbed by the liquid metal before solidification than by the amount of inclusions, acting as hydrogen traps, in the weld metal.

  11. Deposition of aerosol particles and flow resistance in mathematical and experimental airway models.

    PubMed

    Kim, C S; Brown, L K; Lewars, G G; Sackner, M A

    1983-07-01

    Aerosol deposition and flow resistance in obstructed airways were determined from five mathematical and experimental airway models. The first three models were theoretical and based upon Weibel's symmetrical lung model with 1) uniform reduction of airway diameter in various groups of airway generations; 2) obstruction of a few major airways such that a severe uneven flow distribution occurs in the lung; 3) focal constriction of selected large airways. In model 3, an empirical formula was utilized to assess deposition and resistance in the constricted airways. The remaining two models were tested experimentally; 4) oscillation of a compliant wall in a straight tube and 5) two-phase gas-liquid flow utilizing human sputum in a rigid branching tube. In models 1, 2, and 3, airway resistance increased to a greater extent than did the increase of aerosol deposition except when small airways were obstructed in model 1. Here, the increase of aerosol deposition was slightly higher than the rise in airway resistance. A sharp increase of aerosol deposition with a minimal increase of flow resistance was demonstrated in models 4 and 5. These data indicate that aerosol deposition may be a more sensitive indicator of airway abnormalities than overall airway resistance in small airways obstruction, during oscillation of large and medium airway walls, and when excessive secretions within the airways move with a wave or slug motion.

  12. Aerosol deposition favors red tide phytoplankton in the East China Sea

    NASA Astrophysics Data System (ADS)

    Mackey, K. R.; Chien, C.; Chen, Y.; Glover, D. M.; Paytan, A.

    2013-12-01

    Chinese marginal seas support vast fisheries and vital economies, but their productivity is threatened by eutrophication from runoff and atmospheric deposition. The East China Sea is inundated with nitrogen from the Yangtze River and anthropogenic emissions, leading to elevated N:P ratios. We show that aerosol additions approximating one week of moderate deposition to offshore waters favor the growth of red tide phytoplankton, such as Skeletonema costatum, by providing nutrients and trace metals (iron and zinc) needed for growth. In contrast toxin-producing Pseudonitzchia does not benefit from aerosols in this region, possibly due to its preference for lower N:P ratios. A dose-dependent toxic response was observed in Synechococcus at high aerosol loads approximating a week of heavy deposition in the region. In contrast, phytoplankton growth at an onshore station was light limited, and aerosol additions did not have an appreciable effect on phytoplankton growth. Aerosol and chlorophyll observations from the Moderate Resolution Imaging Spectroradiometer (MODIS) satellite have the potential to explore the effect of aerosols on phytoplankton blooms over longer time scales and seasons. This study shows the potential for aerosols to control N:P ratios in offshore waters and to shape the phytoplankton community through fertilization and toxicity, contributing to the occurrence of red tides.

  13. Deposition of aerosol particles in human lungs: in vivo measurements and modeling

    EPA Science Inventory

    The deposition dose and site of inhaled particles within the lung are the key determinants in health risk assessment of particulate pollutants. Accurate dose estimation, however, is a formidable task because aerosol transport and deposition in the lung are governed by many factor...

  14. Modeling Aerosol Particle Deposition on a Person Using Computational Fluid Dynamics

    DTIC Science & Technology

    numerical simulations of aerosol particle deposition on the human form. Numerical simulation of a two-phase turbulent impinging jet flow is studied to...validation show that the standard EIM with turbulent tracking tends to over predict the deposition efficiency. Greatly improved results were achieved by

  15. Is dry deposition of semi-volatile organic gases a significant loss of secondary organic aerosols (SOA)?

    NASA Astrophysics Data System (ADS)

    Hodzic, A.; Aumont, B.; Knote, C. J.; Lee-Taylor, J. M.; Madronich, S.

    2013-12-01

    Dry deposition removal of semi-volatile organic compounds from the atmosphere and its impact on organic aerosol mass is currently under-explored and not well represented in chemistry-climate models, especially for the many complex partly oxidized organics involved in particle formation. The main reason for this omission is that current models use simplified SOA mechanisms that lump precursors and their products into volatility bins, therefore losing information on important properties of individual molecules (or groups) that are needed to calculate dry deposition. In this study, we apply the Generator of Explicit Chemistry and Kinetics of Organics in the Atmosphere (GECKO-A) to simulate SOA formation and estimate the influence of dry deposition of gas-phase organics on SOA concentrations downwind of an urban area (Mexico City), as well as over a pine forest. SOA precursors considered here include short- and long-chain alkanes (C3-25), alkenes, light aromatics, isoprene and monoterpenes. We show that dry deposition of oxidized gases is not an efficient sink for anthropogenic SOA, as it removes <5% of SOA within the city's boundary layer and ~15% downwind. The effect on biogenic SOA is however significantly larger. We discuss reasons for these differences, and investigate separately the impacts on short and long-chain species. We show that the dry deposition is competing with the uptake of gases to the aerosol phase. In the absence of this condensation, ~50% of the regionally produced mass downwind of Mexico City would have been dry-deposited. However, because dry deposition of submicron aerosols is slow, condensation onto particles protects organic gases from deposition and therefore increases their atmospheric burden and lifetime. We use the explicit GECKO-A model to build an empirical parameterization for use in 3D models. Removal (dry and wet) of organic vapors depends on their solubility, and required Henry's law solubility coefficients were estimated for

  16. Quality of wet deposition in the Grand Calumet River watershed, northwestern Indiana, October 17, 1995-November 12, 1996

    USGS Publications Warehouse

    Willoughby, Timothy C.

    2000-01-01

    In June 1992, a wet-deposition collection site was established at the Gary (Indiana) Regional Airport to monitor the quantity and chemical quality of wet deposition. During the first phase of sampling, 48 wet-deposition samples were collected between June 30, 1992, and August 31, 1993. A second phase of sampling began in October 1995. During the second phase of sampling, 40 wet-deposition samples were collected between October 17, 1995, and November 12, 1996. This report presents the findings for the second phase of sampling and compares those results to the first phase of sampling. Northwestern Indiana is a heavily industrialized area. Steel production and petroleum refining are two of the area?s predominant industries. High-temperature processes, such as fossil-fuel combustion and steel production, release contaminants to the atmosphere that may result in wet deposition being a major contributor to major-ion and trace-metal loadings in northwestern Indiana and Lake Michigan. Wet-deposition samples collected during the first and second phases of sampling were analyzed for pH, specific conductance, and selected major ions and trace metals. Forty weekly wet-deposition samples were collected at the Gary (Indiana) Regional Airport during the second phase of sampling. Approximately 1.2 times as much wet deposition was collected during the second phase of sampling compared to the first phase. Statistically significant increases (at the 5-percent significance level) in concentrations of potassium, iron, lead, and zinc were determined for samples collected during the second phase of sampling when compared to the first. No statistically significant differences were determined in constituent concentrations between samples collected during warm weather (April 1 through October 31) and during cold weather (November 1 through March 31). Annual loadings for the second phase of sampling were greater than 2 times the loadings determined during the first phase of sampling for

  17. Wet nitrogen and phosphorus deposition in the eutrophication of the Lagos Lagoon, Nigeria.

    PubMed

    Oladosu, Najeem O; Abayomi, Akeem A; Olayinka, Kehinde O; Alo, Babajide I

    2017-02-15

    Air pollution is influenced by wind-aided particulate suspension, open-air waste burning, and fossil fuel combustion. The pollutants from these sources eventually deposit on ambient surfaces. Atmospheric wet deposition into Lagos Lagoon may be significant additions to the nutrient levels of the eutrophic lagoon. Precipitation was monitored at three stations in the Lagos Lagoon basin from May to November, 2012, in order to estimate the contribution of wet deposition to the nutrient cycles of the lagoon. Water samples were digested with potassium persulfate, and the species of phosphorus (P) and nitrogen (N) were analyzed by colorimetric methods. The mean [NO3(-)+NO2(-)]-N level was 0.39 ± 0.51 kg ha(-1) month(-1). The average total N was 3.16 ± 6.39 kg ha(-1) month(-1). The mean soluble reactive P was lower than the [NO3(-)+NO2(-)]-N averaging 0.06 ± 0.09 (at control site S2) to 0.24 ± 0.10 kg ha(-1) month(-1) (at site S1). Average total P was 1.25 ± 0.82 kg ha(-1) month(-1). The annual total N (May-September) was 4.55 (at S2) to 32.4 kg ha(-1) year(-1) (at S3). The annual total P (May-November) over Lagos Lagoon basin was 5.06 kg ha(-1) year(-1) (at S2). This study demonstrated that wet deposition of anthropogenically derived nutrients to the Lagos Lagoon is ongoing and may represent a considerable proportion of the total nutrient loading to it. The increased P availability in the wet deposition is likely responsible for the water hyacinths, which usually blossom on Lagos Lagoon during the late rainy season, and the reported harmattan-season bottom water hypoxia.

  18. Monitoring of wet deposition in alpine areas in the Sierra Nevada. Final report

    SciTech Connect

    Melack, J.M.; Sickman, J.O.

    1997-01-16

    The quantity and chemical composition of precipitation in the Sierra Nevada was monitored at high elevation stations during the period of 1990 through 1995. From 1990 through 1993, eleven sites were included in the network. For 1994 the number was seven and during the spring of 1995, the snowpack was sampled at six stations. During the course of the study a total of 1546 snow samples were collected from 225 snowpits and an additional 514 non-winter precipitation events were sampled. All major solutes in wet deposition were measured and a rigorous quality assurance-quality control protocol was followed.

  19. Aerosol dry deposition on vegetative canopies. Part II: A new modelling approach and applications

    NASA Astrophysics Data System (ADS)

    Petroff, Alexandre; Mailliat, Alain; Amielh, Muriel; Anselmet, Fabien

    2008-05-01

    This paper presents a new approach for the modelling of aerosol dry deposition on vegetation. It follows a companion article, in which a review of the current knowledge highlights the need for a better description of the aerosol behaviour within the canopy [Petroff, A., Mailliat, A., Amielh, M., Anselmet, F., 2008. Aerosol dry deposition on vegetative canopies. Part I: Review of present knowledge. Atmospheric Environment, in press, doi:10.1016/j.atmosenv.2007.09.043]. Concepts from multi-phase flow studies are used for describing the canopy medium and deriving a time and space-averaged aerosol balance equation and the associated deposition terms. The closure of the deposition terms follows an up-scaling procedure based on the statistical distribution of the collecting elements. This aerosol transport model is then applied in a stationary and mono-dimensional configuration and takes into account the properties of the vegetation, the aerosol and the turbulent flow. Deposition mechanisms are Brownian diffusion, interception, inertial and turbulent impactions, and gravitational settling. For each of them, a parameterisation of the particle collection is derived and the quality of their predictions is assessed by comparison with wind-tunnel deposition measurements on coniferous twigs [Belot, Y., Gauthier, D., 1975. Transport of micronic particles from atmosphere to foliar surfaces. In: De Vries, D.A., Afgan, N.H. (Eds.), Heat and Mass Transfer in the Biosphere. Scripta Book, Washington, DC, pp. 583-591; Belot, Y., 1977. Etude de la captation des polluants atmosphériques par les végétaux. CEA, R-4786, Fontenay-aux-Roses; Belot, Y., Camus, H., Gauthier, D., Caput, C., 1994. Uptake of small particles by canopies. The Science of the Total Environment 157, 1-6]. Under a real canopy configuration, the predictions of the aerosol transport model compare reasonably well with detailed on-site deposition measurements of Aitken mode particles [Buzorius, G., Rannik, Ü., M

  20. Wet deposition of mercury in the U.S. and Canada, 1996-2005: Results and analysis of the NADP mercury deposition network (MDN)

    NASA Astrophysics Data System (ADS)

    Prestbo, Eric M.; Gay, David A.

    One of the most critical measurements needed to understand the biogeochemical cycle of mercury, and to verify atmospheric models, is the rate of mercury wet-deposition. The Mercury Deposition Network (MDN) operates sites across North America to monitor total mercury in wet-deposition. MDN's primary goal is to provide both spatial and temporal continental-scale observations of mercury wet-deposition fluxes to support researchers, modelers, policy-makers and the public interest. MDN represents the only continental-scale mercury deposition database with a >10-year record of continuous values. This study provides analysis and interpretation of MDN observations at 10 years (1996-2005) with an emphasis on investigating whether rigorous, statistically-significant temporal trends and spatial patterns were present and where they occurred. Wet deposition of mercury ranges from more than 25 μg m -2 yr in south Florida to less than 3 μg m -2 yr in northern California. Volume-weighted total mercury concentrations are statistically different between defined regions overall (Southeast ≈ Midwest > Ohio River > Northeast), with the highest in Florida, Minnesota, and several Southwest locations (10-16 ng L -1). Total mercury wet-deposition is significantly different between defined regions (Southeast > Ohio River > Midwest > Northeast). Mercury deposition is strongly seasonal in eastern North America. The average mercury concentration is about two times higher in summer than in winter, and the average deposition is approximately more than three times greater in summer than in winter. Forty-eight sites with validated datasets of five years or more were tested for trends using the non-parametric seasonal Kendall trend test. Significant decreasing mercury wet-deposition concentration trends were found at about half of the sites, particularly across Pennsylvania and extending up through the Northeast.

  1. Uncertainties in aerosol deposition within the respiratory tract using the icrp 66 model: a study in workers.

    PubMed

    Fritsch, P

    2006-02-01

    This study estimates uncertainties in aerosol deposition within the main regions of the human respiratory tract calculated using the ICRP 66 model. Uniform, triangular, normal, or lognormal distributions were assigned to the model parameters, which involve physical properties of aerosols, their inhalability, their thermo- and aerodynamic deposition efficiencies, and the anatomy, physiology, and exertion level of the individuals. Calculations were performed over a range of aerosol sizes from 0.01 to 50 mum. Monodispersed aerosols were characterized by their aerodynamic diameter (dae). Polydispersed aerosols were characterized by their activity median aerodynamic diameters (AMADs) and the geometric standard deviation (GSD) in diameter. Lognormal distributions of particle deposition were generally observed with low GSD (< 2). The highest uncertainties were observed within the deep lung for the smallest and the largest aerosol sizes, which were mainly due either to particle density or to aerodynamic deposition efficiencies and anatomical and physiological variability, respectively. In the case of diameters larger than 5 mum, uncertainties in the deep lung deposition were much more important for monodispersed than for polydispersed aerosols. This was explained both by the size distribution of the deposited aerosol, the median of which corresponded to a maximal dae value of about 7 and 5 in bronchioles and alveoli, respectively, and by the absence of deposition, which occurs for dae equal to or larger than 50 mum, depending on the exertion level. Thus, in the range of AMADs considered, for the four default workers proposed by ICRP 66, uncertainties in aerosol deposition remain low, with GSD smaller than 3.

  2. On the wetting behavior of ceria thin films grown by pulsed laser deposition

    NASA Astrophysics Data System (ADS)

    Fu, Sin-Pui; Rossero, Jorge; Chen, Chen; Li, Daniel; Takoudis, Christos G.; Abiade, Jeremiah T.

    2017-02-01

    Polymers are most widely used in the production of water-repellant coatings. However, their use in applications requiring wear resistance or high-temperature stability is extremely limited. A recent report suggests that wear resistant, thermally stable rare earth oxide materials like cerium dioxide (ceria) are intrinsically water repellant. We have studied this intriguing finding for ceria thin films fabricated by pulsed laser deposition (PLD) at different oxygen pressures and different substrate temperatures. We used a custom apparatus for measuring water contact angles on ceria films deposited by PLD. X-ray photoelectron spectroscopy was used to determine the relationship between the ceria wetting behavior and ceria surface chemistry. Our results show that ceria thin films are intrinsically hydrophilic and that hydrophobicity arises due to adsorption of hydrocarbon species after ˜24 h.

  3. Improving prediction of aerosol deposition in an idealized mouth using large-Eddy simulation.

    PubMed

    Matida, Edgar A; Finlay, Warren H; Breuer, Michael; Lange, Carlos F

    2006-01-01

    Monodisperse aerosol deposition in an idealized mouth geometry with a relatively small inlet diameter (D (in) = 3.0 mm) was studied numerically using a standard Large Eddy Simulation (LES). A steady inhalation flow rate of Q = 32.2 L/min was used. Thousands of particles (2.5, 3.7, and 5.0 microm in diameter and rho (f) = 912.0 kg/m(3) density) were released separately in the computational domain and aerosol deposition was determined. The total aerosol deposition results in this idealized mouth were in relatively good agreement when compared with measured data obtained in separate experiments, showing considerable improvement over the standard RANS/EIM (Reynolds Averaged Navier-Stokes/Eddy Interaction Model) approach.

  4. Deposition of Particles in the Alveolar Airways: Inhalation and Breath-Hold with Pharmaceutical Aerosols

    PubMed Central

    Khajeh-Hosseini-Dalasm, Navvab; Longest, P. Worth

    2014-01-01

    Previous studies have demonstrated that factors such as airway wall motion, inhalation waveform, and geometric complexity influence the deposition of aerosols in the alveolar airways. However, deposition fraction correlations are not available that account for these factors in determining alveolar deposition. The objective of this study was to generate a new space-filling model of the pulmonary acinus region and implement this model to develop correlations of aerosol deposition that can be used to predict the alveolar dose of inhaled pharmaceutical products. A series of acinar models was constructed containing different numbers of alveolar duct generations based on space-filling 14-hedron elements. Selected ventilation waveforms were quick-and-deep and slow-and-deep inhalation consistent with the use of most pharmaceutical aerosol inhalers. Computational fluid dynamics simulations were used to predict aerosol transport and deposition in the series of acinar models across various orientations with gravity where ventilation was driven by wall motion. Primary findings indicated that increasing the number of alveolar duct generations beyond 3 had a negligible impact on total acinar deposition, and total acinar deposition was not affected by gravity orientation angle. A characteristic model containing three alveolar duct generations (D3) was then used to develop correlations of aerosol deposition in the alveolar airways as a function of particle size and particle residence time in the geometry. An alveolar deposition parameter was determined in which deposition correlated with d2t over the first half of inhalation followed by correlation with dt2, where d is the aerodynamic diameter of the particles and t is the potential particle residence time in the alveolar model. Optimal breath-hold times to allow 95% deposition of inhaled 1, 2, and 3 μm particles once inside the alveolar region were approximately >10, 2.7, and 1.2 s, respectively. Coupling of the deposition

  5. Soluble Nutrient and Trace Metal Fluxes from Aerosol Dry Deposition to Elkhorn Slough, CA

    NASA Astrophysics Data System (ADS)

    Gray, E. T.; Paytan, A.; Haskins, J.

    2009-12-01

    Atmospheric deposition has been widely recognized as a source of pollutants and nutrients to coastal ecosystems. Specifically, deposition includes nitrogen compounds, sulfur compounds, mercury, pesticides, phosphate, trace metals and other toxic compounds that can travel great distances in aerosols. These components can come from both natural (volcanoes, mineral dust, forest fires) and anthropogenic (fossil fuels, chemical byproducts, incineration of waste) sources. These pollutants may affect ecosystem health and water quality with environmental impacts such as eutrophication, contaminated fish and harmful algal blooms. In this study we focus on dry deposition to Elkhorn Slough, California. Size fractionated aerosol samples (PM 2.5 and PM 10) collected continuously over a seven day period using a cascade impactor are used along with a deposition model to determine the soluble nutrient and trace metal fluxes on the Elkhorn Slough ecosystem. Atmospheric deposition inputs will be compared to other sources and their potential impact evaluated.

  6. Modeling wet deposition of acid substances over the PRD region in China

    NASA Astrophysics Data System (ADS)

    Lu, Xingcheng; Fung, Jimmy Chi Hung; Wu, Dongwei

    2015-12-01

    The Pearl River Delta (PRD) region in southern China has suffered heavily from acid rain in the last 10 years due to the anthropogenic emission of sulfur dioxide and nitrogen dioxide. Several measurement-based studies about this issue have been conducted to analyze the chemical composition of precipitation in this area. However, no detailed, high resolution numerical simulation regarding this topic has ever been done in this region. In this study, the WRF-SMOKE-CMAQ system was applied to simulate the wet deposition of acid substances (SO42- and NO3-) in the PRD region from 2009 to 2011 with a resolution of 3 km. The simulation output agreed well with the observation data. Our results showed that Guangzhou was the city most affected by acid rain in this region. The ratio of non-sea-salt sulfate to nitrate indicated that the acid rain in this region belonged to the sulfate-nitrate mixed type. The source apportionment result suggests that point source and super regional source are the ones that contribute the pollutants most in the rain water over PRD Region. The sulfate and nitrate input to some reservoirs via wet deposition was also estimated based on the model simulation. Our results suggest that further cross-city cooperation and emission reduction are needed to further curb acid rain in this region.

  7. Lacustrine responses to decreasing wet mercury deposition rates: results from a case study in northern Minnesota

    USGS Publications Warehouse

    Brigham, Mark E.; Sandheinrich, Mark B.; Gay, David A.; Maki, Ryan P.; Krabbenhoft, David P.; Wiener, James G.

    2014-01-01

    We present a case study comparing metrics of methylmercury (MeHg) contamination for four undeveloped lakes in Voyageurs National Park to wet atmospheric deposition of mercury (Hg), sulfate (SO4–2), and hydrogen ion (H+) in northern Minnesota. Annual wet Hg, SO4–2, and H+ deposition rates at two nearby precipitation monitoring sites indicate considerable decreases from 1998 to 2012 (mean decreases of 32, 48, and 66%, respectively). Consistent with decreases in the atmospheric pollutants, epilimnetic aqueous methylmercury (MeHgaq) and mercury in small yellow perch (Hgfish) decreased in two of four lakes (mean decreases of 46.5% and 34.5%, respectively, between 2001 and 2012). Counter to decreases in the atmospheric pollutants, MeHgaq increased by 85% in a third lake, whereas Hgfish increased by 80%. The fourth lake had two disturbances in its watershed during the study period (forest fire; changes in shoreline inundation due to beaver activity); this lake lacked overall trends in MeHgaq and Hgfish. The diverging responses among the study lakes exemplify the complexity of ecosystem responses to decreased loads of atmospheric pollutants.

  8. Wet deposition of hydrocarbons in the city of Tehran-Iran

    PubMed Central

    Pardakhti, Alireza; Mohajeri, Leila; Bateni, Farshid

    2009-01-01

    Air pollution in the city of Tehran has been a major problem for the past three decades. The direct effects of hydrocarbon contaminants in the air are particularly important such as their carcinogenic, mutagenic, and teratogenic effects which can be transported to other environments via dry and wet deposition. In the present study, rainwater samples were collected and analyzed for 16 polycyclic aromatic hydrocarbons (PAHs), benzene, toluene, ethyl benzene, and xylene (BTEX) as well as fuel fingerprints in two ranges of gasoline (C5–C11) and diesel fuel (C12–C20) using a gas chromatograph equipped with a flame ionization detector (GC/FID). Mean concentrations of ∑16 PAHs varied between 372 and 527 µg/L and for BTEX was between 87 and 188 µg/L with maximum of 36 µg/L for toluene. Both gasoline range hydrocarbons (GRH) and diesel range hydrocarbons (DRH) were also present in the collected rainwater at concentrations of 190 and 950 µg/L, respectively. Hydrocarbon transports from air to soil were determined in this wet deposition. Average hydrocarbon transportation for ∑PAHs, BTEX, GRH, and DRH was 2,747, 627, 1,152, and 5,733 µg/m2, respectively. PMID:20495601

  9. Wet deposition of hydrocarbons in the city of Tehran-Iran.

    PubMed

    Zahed, Mohammad Ali; Pardakhti, Alireza; Mohajeri, Leila; Bateni, Farshid

    2010-06-01

    Air pollution in the city of Tehran has been a major problem for the past three decades. The direct effects of hydrocarbon contaminants in the air are particularly important such as their carcinogenic, mutagenic, and teratogenic effects which can be transported to other environments via dry and wet deposition. In the present study, rainwater samples were collected and analyzed for 16 polycyclic aromatic hydrocarbons (PAHs), benzene, toluene, ethyl benzene, and xylene (BTEX) as well as fuel fingerprints in two ranges of gasoline (C5-C11) and diesel fuel (C12-C20) using a gas chromatograph equipped with a flame ionization detector (GC/FID). Mean concentrations of summation operator16 PAHs varied between 372 and 527 microg/L and for BTEX was between 87 and 188 microg/L with maximum of 36 microg/L for toluene. Both gasoline range hydrocarbons (GRH) and diesel range hydrocarbons (DRH) were also present in the collected rainwater at concentrations of 190 and 950 microg/L, respectively. Hydrocarbon transports from air to soil were determined in this wet deposition. Average hydrocarbon transportation for summation operatorPAHs, BTEX, GRH, and DRH was 2,747, 627, 1,152, and 5,733 microg/m(2), respectively.

  10. Aqueous-Phase Reactions of Isoprene with Sulfoxy Radical Anions as a way of Wet Aerosol Formation in the Atmosphere

    NASA Astrophysics Data System (ADS)

    Kuznietsova, I.; Rudzinski, K. J.; Szmigielski, R.; Laboratory of the Environmental Chemistry

    2011-12-01

    Atmospheric aerosols exhibit an important role in the environment. They have implications on human health and life, and - in the larger scale - on climate, the Earth's radiative balance and the cloud's formation. Organic matter makes up a significant fraction of atmospheric aerosols (~35% to ~90%) and may originate from direct emissions (primary organic aerosol, POA) or result from complex physico-chemical processes of volatile organic compounds (secondary organic aerosol, SOA). Isoprene (2-methyl-buta-1,3-diene) is one of the relevant volatile precursor of ambient SOA in the atmosphere. It is the most abundant non-methane hydrocarbon emitted to the atmosphere as a result of living vegetation. According to the recent data, the isoprene emission rate is estimated to be at the level of 500 TgC per year. While heterogeneous transformations of isoprene have been well documented, aqueous-phase reactions of this hydrocarbon with radical species that lead to the production of new class of wet SOA components such as polyols and their sulfate esters (organosulfates), are still poorly recognized. The chain reactions of isoprene with sulfoxy radical-anions (SRA) are one of the recently researched route leading to the formation of organosulfates in the aqueous phase. The letter radical species originate from the auto-oxidation of sulfur dioxide in the aqueous phase and are behind the phenomenon of atmospheric acid rain formation. This is a complicated chain reaction that is catalyzed by transition metal ions, such as manganese(II), iron(III) and propagated by sulfoxy radical anions . The presented work addresses the chemical interaction of isoprene with sulfoxy radical-anions in the water solution in the presence of nitrite ions and nitrous acid, which are important trace components of the atmosphere. We showed that nitrite ions and nitrous acid significantly altered the kinetics of the auto-oxidation of SO2 in the presence of isoprene at different solution acidity from 2 to 8

  11. Aerosol transport and wet scavenging in deep convective clouds: a case study and model evaluation using a multiple passive tracer analysis approach

    SciTech Connect

    Yang, Qing; Easter, Richard C.; Campuzano-Jost, Pedro; Jimenez, Jose L.; Fast, Jerome D.; Ghan, Steven J.; Wang, Hailong; Berg, Larry K.; Barth, Mary; Liu, Ying; Shrivastava, ManishKumar B.; Singh, Balwinder; Morrison, H.; Fan, Jiwen; Ziegler, Conrad L.; Bela, Megan; Apel, Eric; Diskin, G. S.; Mikoviny, Tomas; Wisthaler, Armin

    2015-08-20

    The effect of wet scavenging on ambient aerosols in deep, continental convective clouds in the mid-latitudes is studied for a severe storm case in Oklahoma during the Deep Convective Clouds and Chemistry (DC3) field campaign. A new passive-tracer based transport analysis framework is developed to characterize the convective transport based on the vertical distribution of several slowly reacting and nearly insoluble trace gases. The passive gas concentration in the upper troposphere convective outflow results from a mixture of 47% from the lower level (0-3 km), 21% entrained from the upper troposphere, and 32% from mid-atmosphere based on observations. The transport analysis framework is applied to aerosols to estimate aerosol transport and wet-scavenging efficiency. Observations yield high overall scavenging efficiencies of 81% and 68% for aerosol mass (Dp < 1μm) and aerosol number (0.03< Dp < 2.5μm), respectively. Little chemical selectivity to wet scavenging is seen among observed submicron sulfate (84%), organic (82%), and ammonium (80%) aerosols, while nitrate has a much lower scavenging efficiency of 57% likely due to the uptake of nitric acid. Observed larger size particles (0.15 - 2.5μm) are scavenged more efficiently (84%) than smaller particles (64%; 0.03 - 0.15μm). The storm is simulated using the chemistry version of the WRF model. Compared to the observation based analysis, the standard model underestimates the wet scavenging efficiency for both mass and number concentrations with low biases of 31% and 40%, respectively. Adding a new treatment of secondary activation significantly improves simulation results, so that the bias in scavenging efficiency in mass and number concentrations is reduced to <10%. This supports the hypothesis that secondary activation is an important process for wet removal of aerosols in deep convective storms.

  12. Measurement of total lung aerosol deposition as an index of lung abnormality.

    PubMed

    Kim, C S; Lewars, G A; Sackner, M A

    1988-04-01

    Total aerosol deposition in the lung was measured in 100 subjects with various lung conditions. The subjects consisted of 40 normals (N), 15 asymptomatic smokers (S), 10 smokers with small airway disease (SAD), 20 with chronic simple bronchitis (SB), and 15 with chronic obstructive bronchitis (COPD), and a relationship of total aerosol deposition to degree of lung abnormality was investigated. The subjects were categorized by medical history and a battery of pulmonary function tests, including spirometry, body plethysmography, and single and multiple N2 washout measurements. Subjects repeatedly breathed a monodisperse test aerosol (1.0 micron diam) from a collapsible rebreathing bag (0.5 liter volume) at a rate of 30 breaths/min, while inhaled and exhaled aerosol concentrations were continuously monitored by a laser aerosol photometer in situ and recorded on a strip-chart recorder. The number of rebreathing breaths resulting in 90% aerosol loss from the bag (N90) was determined, and percent predicted N90 values were then determined from the results of computer simulation and used as a deposition index. The percent predicted N90 values were 99.7 +/- 14, 86.5 +/- 15, 66.9 +/- 17, 51 +/- 12, and 30.9 +/- 9, respectively, for N, S, SAD, SB, and COPD. All of these values were significantly different from each other (P less than 0.05). There was no difference between male and female but percent predicted N90 values were slightly higher in young than in old normals. Percent predicted N90 values showed a strong linear correlation with spirometric measurements of forced expiratory volume in 1 s and maximum midexpiratory flow rate. However, many of the SAD and SB with normal spirometry showed abnormal N90. These results suggest that total lung aerosol deposition is a sensitive index of lung abnormality and may be of potential use for nonspecific general patient screening.

  13. Relationship between site-specific nitrogen concentrations in mosses and measured wet bulk atmospheric nitrogen deposition across Europe.

    PubMed

    Harmens, Harry; Schnyder, Elvira; Thöni, Lotti; Cooper, David M; Mills, Gina; Leblond, Sébastien; Mohr, Karsten; Poikolainen, Jarmo; Santamaria, Jesus; Skudnik, Mitja; Zechmeister, Harald G; Lindroos, Antti-Jussi; Hanus-Illnar, Andrea

    2014-11-01

    To assess the relationship between nitrogen concentrations in mosses and wet bulk nitrogen deposition or concentrations in precipitation, moss tissue and deposition were sampled within a distance of 1 km of each other in seven European countries. Relationships for various forms of nitrogen appeared to be asymptotic, with data for different countries being positioned at different locations along the asymptotic relationship and saturation occurring at a wet bulk nitrogen deposition of ca. 20 kg N ha(-1) yr(-1). The asymptotic behaviour was more pronounced for ammonium-N than nitrate-N, with high ammonium deposition at German sites being most influential in providing evidence of the asymptotic behaviour. Within countries, relationships were only significant for Finland and Switzerland and were more or less linear. The results confirm previous relationships described for modelled total deposition. Nitrogen concentration in mosses can be applied to identify areas at risk of high nitrogen deposition at European scale.

  14. Characteristics of total and methyl mercury in wet deposition in a coastal city, Xiamen, China: Concentrations, fluxes and influencing factors on Hg distribution in precipitation

    NASA Astrophysics Data System (ADS)

    Xu, Lingling; Chen, Jinsheng; Yang, Liming; Yin, Liqian; Yu, Jianshuang; Qiu, Tianxue; Hong, Youwei

    2014-12-01

    Daily precipitation samples were collected from June 2012 to May 2013 at four observation sites in Xiamen, a coastal city of Southeast China. Concentrations of Total mercury (THg) and methyl mercury (MeHg) in precipitation were rigorously treated and determined. The annual volume-weighted mean concentrations of THg and MeHg at four sites were 12.3 and 0.053 ng L-1, and wet deposition fluxes of THg and MeHg were 14.04 μg m-2 yr-1 and 58.2 ng m-2 yr-1, respectively. MeHg could account for 0.43% of THg, and dissolved Hg contributed 55.4% to THg. There was no significant difference in THg concentration between monsoon and non-monsoon seasons, which was consistent with neither the general seasonal pattern of inland cities of China nor the report from the Gulf coast. Higher wet deposition flux of THg in monsoon season was a function of intense rainfall, whereas higher MeHg flux in non-monsoon season could attribute to increased MeHg concentration. Atmospheric Hg was more efficiently scavenged during the earlier period of the rain event. Positive correlations between precipitation depth and wet deposition fluxes suggested that rainfall played an important role in scavenging atmospheric Hg rather than diluting concentrations. Pearson correlation analysis combined with ions ratios implied that sea salt aerosols had an important impact on rainwater, but coal combustion and traffic emission could be the dominant factors influencing THg in precipitation.

  15. [Chemical Characteristics of Atmospheric Wet Deposition in Winter and Its Forestry Canopy Interception Mechanism in Red Soil Hilly Area].

    PubMed

    Hao, Zhuo; Gao, Yang; Zhang, Jin-zhong; Yu, Gui-rui

    2015-12-01

    In order to disclose the interception mechanism of forestry canopy to atmospheric wet deposition, the concentrations of nutrients (C, N, P, S) and trace elements (K, Ca, Na, Mg, Al, Fe, Mn, Zn) in wet deposition and through fall in winter were monitored in Subtropical Qiananzhou basin. The results showed that the wet deposition in this area was mainly acid deposition, the pH of which ranged from 3.49 to 7.0. The major components of wet deposition were nitrate (NO₃⁻) and sulfate ions (SO₄²⁻), the monthly average deposition fluxes of which were 4.68 kg · hm⁻² and 0.36 kg · hm⁻², and trace elements (Zn, K, Ca) with monthly average deposition fluxes of 1.72, 0.56 and 0.36 kg · hm⁻², respectively. Non-metallic nutrients such as dissolved organic carbon (DOC) , dissolved total nitrogen (DTN), total phosphorus (TP), Ca, Mg and Mn were easy to leach, the dilution rate could reach up to 64.69%, 206.75%, 301.38%, 137.94%, 405.25% and 1226.60%, respectively. Moreover, the Zn and sulfate ion (SO₄²⁻) could be well absorbed by forests canopy, the absorption proportions of which were 73.50% and 12.51%, respectively.

  16. Atmospheric aerosol deposition influences marine microbial communities in oligotrophic surface waters of the western Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Maki, Teruya; Ishikawa, Akira; Mastunaga, Tomoki; Pointing, Stephen B.; Saito, Yuuki; Kasai, Tomoaki; Watanabe, Koichi; Aoki, Kazuma; Horiuchi, Amane; Lee, Kevin C.; Hasegawa, Hiroshi; Iwasaka, Yasunobu

    2016-12-01

    Atmospheric aerosols contain particulates that are deposited to oceanic surface waters. These can represent a major source of nutrients, trace metals, and organic compounds for the marine environment. The Japan Sea and the western Pacific Ocean are particularly affected by aerosols due to the transport of desert dust and industrially derived particulate matter with aerodynamic diameter less than 2.5 μm (PM2.5) from continental Asia. We hypothesized that supplementing seawater with aerosol particulates would lead to measurable changes in surface water nutrient composition as well as shifts in the marine microbial community. Shipboard experiments in the Pacific Ocean involved the recovery of oligotrophic oceanic surface water and subsequent supplementation with aerosol particulates obtained from the nearby coastal mountains, to simulate marine particulate input in this region. Initial increases in nitrates due to the addition of aerosol particulates were followed by a decrease correlated with the increase in phytoplankton biomass, which was composed largely of Bacillariophyta (diatoms), including Pseudo-nitzschia and Chaetoceros species. This shift was accompanied by changes in the bacterial community, with apparent increases in the relative abundance of heterotrophic Rhodobacteraceae and Colwelliaceae in aerosol particulate treated seawater. Our findings provide empirical evidence revealing the impact of aerosol particulates on oceanic surface water microbiology by alleviating nitrogen limitation in the organisms.

  17. Seasonal and annual variations and regional characteristics of wet and dry deposition amounts in East Asian region

    NASA Astrophysics Data System (ADS)

    Sato, K.; Tsuyoshi, O.; Endo, T.; Yagoh, H.; Matsuda, K.

    2011-12-01

    Emission of sulfur and nitrogen compounds in Asian region has been remarkably increased with recent rapid economical growth (Ohara et al., 2007). To appropriately assess the influence of air pollutants on the ecosystem, it is important to quantitatively determine the atmospheric deposition of air pollutants. Here, Seasonal and annual variations and regional characteristics of estimated wet and dry deposition amounts at 27 monitoring sites of Acid Deposition Monitoring Network in East Asia (EANET) from 2003 to 2009 are discussed. Wet deposition sample was collected every 24 hours or 1 week by a wet only sampler. Wet deposition amounts were calculated by the product of the volume-weighted concentrations of ionic species (SO42-, NO3-, and NH4+) in the precipitation and precipitation amount measured by a standard rain gauge at each site. Dry deposition amount was estimated by the inferential method which was originated the model developed by Wesely and Hicks (1977) and modified by Matsuda (2008). The components examined for dry deposition were sulfur compounds (gaseous SO2 and particulate SO42-) and nitrogen compounds (gaseous HNO3 and NH3, particulate NO3- and NH4+). Dry deposition was calculated by the product of the deposition velocity estimated by the inferential method for forest and grass surfaces and the monitored air concentration of each compound. The mean annual dry deposition amounts for sulfur and nitrogen compounds in Japanese sites were in the range of 5-37 and 7-50 mmol m-2 year-1, respectively. The regional characteristics of dry deposition amounts in Japan were similar between sulfur and nitrogen compounds, which showed higher deposition in the Sea of Japan side and the western Japan. The mean annual total (wet + dry) deposition amounts for sulfur and nitrogen compounds in Japanese sites were in the range of 28-77 and 22-130 mmol m-2 year-1, respectively. The contributions of dry deposition to the total deposition amounts were 10-55% and 13-56% for

  18. Mineral dust over west and central Sahel: Seasonal patterns of dry and wet deposition fluxes from a pluriannual sampling (2006-2012)

    NASA Astrophysics Data System (ADS)

    Marticorena, B.; Chatenet, B.; Rajot, J. L.; Bergametti, G.; Deroubaix, A.; Vincent, J.; Kouoi, A.; Schmechtig, C.; Coulibaly, M.; Diallo, A.; Koné, I.; Maman, A.; NDiaye, T.; Zakou, A.

    2017-01-01

    Total and wet mineral dust deposition has been monitored since 2006 at three Sahelian stations in Senegal, Mali, and Niger, respectively at the weekly and the event time scale. Average annual deposited mass fluxes range from 75 to 183 g m-2 yr-1, from west to east. Deposition fluxes exhibit a clear seasonal cycle in Mali and Niger. High wet deposition fluxes result from an optimum phasing between dust concentration and precipitation: the maximum occurring at the beginning of the wet season, after the maximum of dust concentration and before the precipitation maximum. The contribution of wet to total deposition varies from 67% in Mali to 8% in Senegal. It is the main factor of variability of the deposition fluxes from year to year and at the seasonal scale in Niger and Mali. Wet deposition fluxes in Mali and Niger are mainly due to the wash out of dust emitted by convective systems. In Senegal, the deposition fluxes are lower and dominated by dry deposition (92% of the annual deposition flux). This is due to the low occurrence of convective systems producing local dust emissions and intense wet deposition. The dry deposition fluxes are primarily driven by the variability of the dust concentration. The dry deposition velocities derived from our measurements are consistent with those estimated by theoretical models. Scavenging ratios computed from the measured wet deposition fluxes, dust concentrations, and precipitation are anticorrelated with precipitation amounts. This suggests that most of the atmospheric dust is scavenged at the very beginning of the precipitation events.

  19. Microfog lubricant application system for advanced turbine engine components, phase 3. [wetting characteristics and deposit forming tendencies of lubricants

    NASA Technical Reports Server (NTRS)

    Petrucco, R. J.; Leonardi, S. J.

    1973-01-01

    The wetting characteristics and deposit forming tendencies of a series of lubricants were evaluated using a microfog jet delivery system to wet a flat heated rotating disc. The performances of the nine lubricants are discussed in terms of the various testing parameters which include temperature, disc speed and lubricant gas flow rates. Also discussed are the heat transfer characteristics of two of the lubricants on that same plane disc specimen. The wetting characteristics and heat transfer characteristics of one of the lubricants on a complex disc simulating bearing geometry are also discussed.

  20. ANALYSIS OF RESPIRATORY DEPOSITION OF INHALED AMBIENT AEROSOLS FOR DIFFERENT DOSE METRICS

    EPA Science Inventory

    ANALYSIS OF RESPIRATORY DEPOSITION OF INHALED AMBIENT AEROSOLS FOR DIFFERENT DOSE METRICS.
    Chong S. Kim, SC. Hu**, PA Jaques*, US EPA, National Health and Environmental Effects Research Laboratory, Research Triangle Park, NC 27711; **IIT Research Institute, Chicago, IL; *South...

  1. An assessment of the variability in performance of wet atmospheric deposition samplers

    USGS Publications Warehouse

    Graham, R.C.; Robertson, J.K.; Obal, John

    1987-01-01

    The variability in performance of two brands of wet/dry atmospheric deposition samplers were compared for 1 year at a sincle site. A total of nine samplers were used. Samples were collected weekly and analyzed for pH, specific conductance, common chemical constituents, and sample volume. Additionally, data on the duration of each sampler opening were recorded using a microdatalogger. These data disprove the common perception that samplers remain open throughout a precipitation event. The sensitivity of sampler sensors within the range tested did not have a defineable impact on sample collection. The nonnormal distribution within the data set necessitated application of the nonparametric Friedman Test to assess comparability of sample chemical composition and volume between and within sampler brands. Statistically significant differences existed for most comparisons, however the test did not permit quantification of their magnitudes. Differences in analyte concentrations between samplers were small. (USGS)

  2. Oxidation Kinetics of Chemically Vapor-Deposited Silicon Carbide in Wet Oxygen

    NASA Technical Reports Server (NTRS)

    Opila, Elizabeth J.

    1994-01-01

    The oxidation kinetics of chemically vapor-deposited SiC in dry oxygen and wet oxygen (P(sub H2O) = 0.1 atm) at temperatures between 1200 C and 1400 C were monitored using thermogravimetric analysis. It was found that in a clean environment, 10% water vapor enhanced the oxidation kinetics of SiC only very slightly compared to rates found in dry oxygen. Oxidation kinetics were examined in terms of the Deal and Grove model for oxidation of silicon. It was found that in an environment containing even small amounts of impurities, such as high-purity Al2O3 reaction tubes containing 200 ppm Na, water vapor enhanced the transport of these impurities to the oxidation sample. Oxidation rates increased under these conditions presumably because of the formation of less protective sodium alumino-silicate scales.

  3. Control over the preferred orientation of CIGS films deposited by magnetron sputtering using a wetting layer

    NASA Astrophysics Data System (ADS)

    Yan, Yong; Jiang, Fan; Liu, Lian; Yu, Zhou; Zhang, Yong; Zhao, Yong

    2016-01-01

    A growth method is presented to control the preferred orientation in chalcopyrite CuIn x Ga1- x Se2 (CIGS) thin films grown by magnetron sputtering. Films with (220/204) and (112) preferred orientation as well as randomly oriented films were prepared. The effects of an In2Se3 wetting layer and the working pressure on the texture transition phenomena were examined. A large-grained CIGS film with (220/204) texture was formed at 400°C with the inclusion of a thin (80 nm) In2Se3 layer and liquid phase (excess copper selenide phase) formation, and the reaction mechanism is proposed. The device deposited at 2.0 Pa on an In2Se3 layer exhibited the optimal electrical properties. [Figure not available: see fulltext.

  4. Rainwater trifluoroacetic acid (TFA) in Guangzhou, South China: levels, wet deposition fluxes and source implication.

    PubMed

    Wang, Qiaoyun; Wang, Xinming; Ding, Xiang

    2014-01-15

    The origin of trifluoroacetic acid (TFA) occurring in hydrosphere has long been a controversial issue. Hydrochlorofluorocarbons and hydrofluorocarbons (HCFCs/HFCs) as replacements of chlorofluorocarbons (CFCs) are precursors of TFA in the atmosphere, their contribution to rainwater TFA is a concern as their ambient mixing ratios are continually growing. Here we present rainwater TFA monitored from April 2007 to March 2008 in urban Guangzhou, a central city in south China's highly industrialized and densely populated Pearl River Delta region. Rainwater TFA levels ranged 45.8-974 ng L(-1) with a median of 166 ng L(-1). TFA levels negatively correlated with rainfall amount, the yearly rainfall-weighted average for TFA was 152 ng L(-1). The annual TFA wet deposition flux was estimated to be 229 g km(-2) yr(-1), and the total wet deposition of TFA reached ~1.7 tyr(-1) in Guangzhou. The Two-Box model was applied to estimate attributions of HCFCs/HFCs and fluoropolymers to rainwater TFA assuming TFA generated was proportional to gross domestic product (GDP), gross industrial product (GIP) or number of private cars. The results revealed that the degradation of HCFCs/HFCs and fluoropolymers could explain 131.5-152.4 ng L(-1) rainwater TFA, quite near the observed rainfall-weighted annual mean of 152 ng L(-1), suggesting rainwater TFA in Guangzhou was predominantly originated from these anthropogenic precursors. HCFCs/HFCs accounted for 83.3-96.5% of rainwater TFA observed, while fluoropolymers' contributions were minor (~5%). HFC-134a alone could explain 55.9-90.0% of rainwater TFA, and its contribution would be greatly enhanced with its wide use in mobile air conditioning systems and rapid increase in ambient mixing ratios.

  5. Trends in the composition of wet deposition: effects of the atmospheric rehabilitation in East-Germany

    NASA Astrophysics Data System (ADS)

    Marquardt, Wolfgang; Brüggemann, Erika; Ihle, Peter

    1996-07-01

    The chemical components in precipitation largely depend on type and quantity of emissions on the course of the air masses at the sampling site. Beginning in 1982, the concentrations of major ions in precipitation at initially 3 sites are described in total as well as arrival sectors. For regions with specific geographical or emission features, 5 to 7 sectors for every sampling site are established, e.g., Scandinavia, or the centres of brown coal combustion in the former GDR. Particulary from the sectors of the former GDR, the precipitation was over-averaged contaminated anthropogenically in the years before the political change. Some components were significantly raised in comparison to other sectors. However, acidity remained on the level of the other sectors in the 80s. In the early 90s, anthropogenic emissions were systematically reduced partly by substitution of brown coal of inferior quality, better flue gas cleaning and partly by closing down industries. The effect of such steps on the wet deposition is being studied in a national German SANA research project (SANA: scientific program of rehabilitation of the atmosphere). In this project, the sampling sites were extended to 7 while maintaining the sampling procedure and the recording of relevant meteorological input-data. As a result, there now exists a homogeneous long-term data base allowing us to study the effects of emissions on wet deposition by the rehabilitation of the atmosphere in the former GDR. The paper focusses on changes in sulphate, nitrate, calcium, acidity, chloride and potassium concentrations in precipitation at the 3 so-called long-term sites. There are conspicuous decreases of some ions on one hand, but there is also an increase of nitrate and acidity, especially in recent years.

  6. Quality of wet deposition in the Grand Calumet River watershed, northwestern Indiana, April 29, 1997-April 28, 1998

    USGS Publications Warehouse

    Willoughby, Timothy C.

    2000-01-01

    The Grand Calumet River, in northwestern Indiana, drains a heavily industrialized area along the southern shore of Lake Michigan. Steel production and petroleum refining are two of the area?s predominant industries. High-temperature processes, such as fossilfuel combustion and steel production, release contaminants to the atmosphere that may result in wet deposition being a major contributor to major-ion and trace-metal loadings in northwestern Indiana and Lake Michigan. A wet-deposition collection site was established at the Gary (Indiana) Regional Airport to monitor the quantity and chemical quality of wet deposition. During a first phase of sampling, 48 wet-deposition samples were collected weekly between June 30, 1992, and August 31, 1993. During a second phase of sampling, 40 wet-deposition samples were collected between October 17, 1995, and November 12, 1996. Forty-two wet-deposition samples were collected during a third phase of sampling, which began April 29, 1997, and was completed April 28, 1998. Wetdeposition samples were analyzed for pH, specific conductance, and selected major ions and trace metals. This report describes the quantity and quality of wet-deposition samples collected during the third sampling phase and compares these findings to the results of the first and second sampling phases. All of the samples collected during the third phase of sampling were of sufficient volumes for at least some of the analyses to be performed. Constituent concentrations from the third sampling phase were not significantly different (at the 5-percent significance level) from those for the second sampling phase. Significant increases, however, were observed in the concentrations of potassium, iron, lead, and zinc when compared to the concentrations observed in the first sampling phase. Weekly loadings were estimated for each constituent measured during the third sampling phase. If constituent concentrations were reported less than the method reporting limit, a

  7. Aerosol deposition along the respiratory tract at zero gravity: a theoretical study

    SciTech Connect

    Lehnert, B.E.; Smith, D.M.; Holland, L.M.; Tillery, M.I.; Thomas, R.G.

    1984-01-01

    Significant fractions of airborne particles composing inhaled aerosols can deposit along the respiratory tract during breathing. Depending on the environmental condition, some particles that enter the body via the respiratory route can pose health hazards. On earth, three general rate mechanisms are active in this deposition process: (1) inertial impaction; (2) diffusion; and (3) gravity-dependent sedimentation. Space craft, stations, and bases represent unique settings where potentially pathogenic aerosols may be encountered under the unique condition of zero or reduced gravity. The present study was undertaken in order to predict how particle deposition in the human respiratory tract at zero gravity may differ from that on earth. We employed the aerosol deposition model of the Task Group on Lung Dynamics to assess the regional deposition of particles ranging from 0.01 to 10 ..mu..m diameter at two particulate densities, 1 and 4, during simulated tidal breathing and breathing during moderate - heavy exercise. Our results suggest the gas exchange regions of the lungs of space travelers and residents are afforded some protection, relative to their earth-bound counterparts, against the deposition of particles due to the absence of gravity; and approximately 2 to 10 fold reduction in the efficiency of collection of particles > 0.5 ..mu..m in diameter occurred in the pulmonary region during resting conditions and exercise. Deposition along the tracheobronchial tree, however, is not markedly altered in the absence of gravity, indicating airway sites contributing to this structure remain susceptible to insults by inhaled aerosols. 18 references, 2 figures, 2 tables.

  8. Supersonic jet deposition of silver nanoparticle aerosols: Correlations of impact conditions and film morphologies

    SciTech Connect

    Huang, Chong; Nichols, William T.; O'Brien, Daniel T.; Becker, Michael F.; Kovar, Desiderio; Keto, John W.

    2007-03-15

    We describe experiments and modeling for the deposition of silver lines and films via the impaction of a silver nanoparticle aerosol delivered through a supersonic jet. The aerosol gas dynamics of the jet flow field, nanoparticle acceleration in the jet, and deposition by impaction onto the substrate were modeled for both a flat-plate nozzle and for a conical nozzle designed to obtain higher impaction velocities. We modeled nanoparticle dynamics for He, Ar, and N{sub 2} gasses, all initially at room temperature and 1 atm pressure, flowing through a 250 {mu}m orifice into vacuum with a pressure ratio of {approx}5000. Experiments were conducted to deposit silver nanoparticle aerosols under the same conditions as were modeled. The silver nanoparticles were generated by laser ablation of a flowing microparticle aerosol entrained in either He or Ar that produced nanoparticles 5-10 and 15-20 nm in diameter, respectively. Deposition was made onto an unheated substrate in vacuum. The morphology of the deposited films was determined by scanning electron microscope cross-section images and crystallite size was determined by x-ray diffraction analysis. The morphological features and crystallite size were correlated with the nanoparticle impaction velocity and impaction energy derived from the model. We found that, for a given gas type, the size of the grains and morphological features within the impacted films were similar to the size of the nanoparticles from which the films were formed. The density and the degree of consolidation of the films were highly dependent on the nanoparticle impaction velocity/energy and were highest for helium. Control of film morphology, grain size, and film density during supersonic impaction of nanoparticle aerosols are discussed in light of these results.

  9. Hygroscopic aerosol deposition in the human upper respiratory tract under various thermo-humidity conditions.

    PubMed

    Xi, Jinxiang; Kim, Jongwon; Si, Xiuhua A; Zhou, Yue

    2013-01-01

    The deposition of hygroscopic aerosols is highly complex in nature, which results from a cumulative effect of dynamic particle growth and the real-time size-specific deposition mechanisms. The objective of this study is to evaluate hygroscopic effects on the particle growth, transport, and deposition of nasally inhaled aerosols across a range of 0.2-2.5 μm in an adult image-based nose-throat model. Temperature and relative humidity fields were simulated using the LRN k-ω turbulence model and species transport model under a spectrum of thermo-humidity conditions. Particle growth and transport were simulated using a well validated Lagrangian tracking model coupled with a user-defined hygroscopic growth module. Results of this study indicate that the saturation level and initial particle size are the two major factors that determine the particle growth rate (d/d0), while the effect of inhalation flow rate is found to be not significant. An empirical correlation of condensation growth of nasally inhaled hygroscopic aerosols in adults has been developed based on a variety of thermo-humidity inhalation conditions. Significant elevated nasal depositions of hygroscopic aerosols could be induced by condensation growth for both sub-micrometer and small micrometer particulates. In particular, the deposition of initially 2.5 μm hygroscopic aerosols was observed to be 5-8 times that of inert particles under warm to hot saturated conditions. Results of this study have important implications in exposure assessment in hot humid environments, where much higher risks may be expected compared to normal conditions.

  10. Indoor aerosol modeling for assessment of exposure and respiratory tract deposited dose

    NASA Astrophysics Data System (ADS)

    Hussein, Tareq; Wierzbicka, Aneta; Löndahl, Jakob; Lazaridis, Mihalis; Hänninen, Otto

    2015-04-01

    Air pollution is one of the major environmental problems that influence people's health. Exposure to harmful particulate matter (PM) occurs both outdoors and indoors, but while people spend most of their time indoors, the indoor exposures tend to dominate. Moreover, higher PM concentrations due to indoor sources and tightness of indoor environments may substantially add to the outdoor originating exposures. Empirical and real-time assessment of human exposure is often impossible; therefore, indoor aerosol modeling (IAM) can be used as a superior method in exposure and health effects studies. This paper presents a simple approach in combining available aerosol-based modeling techniques to evaluate the real-time exposure and respiratory tract deposited dose based on particle size. Our simple approach consists of outdoor aerosol data base, IAM simulations, time-activity pattern data-base, physical-chemical properties of inhaled aerosols, and semi-empirical deposition fraction of aerosols in the respiratory tract. These modeling techniques allow the characterization of regional deposited dose in any metric: particle mass, particle number, and surface area. The first part of this presentation reviews recent advances in simple mass-balance based modeling methods that are needed in analyzing the health relevance of indoor exposures. The second part illustrates the use of IAM in the calculations of exposure and deposited dose. Contrary to previous methods, the approach presented is a real-time approach and it goes beyond the exposure assessment to provide the required information for the health risk assessment, which is the respiratory tract deposited dose. This simplified approach is foreseen to support epidemiological studies focusing on exposures originating from both indoor and outdoor sources.

  11. A new sampler for collecting separate dry and wet atmospheric depositions of trace organic chemicals

    NASA Astrophysics Data System (ADS)

    Waite, Don T.; Cessna, Allan J.; Gurprasad, Narine P.; Banner, James

    Studies conducted in Saskatchewan and elsewhere have demonstrated the atmospheric transport of agricultural pesticides and other organic contaminants and their deposition into aquatic ecosystems. To date these studies have focused on ambient concentrations in the atmosphere and in wet precipitation. To measure the dry deposition of organic chemicals, a new sampler was designed which uses a moving sheet of water to passively trap dry particles and gasses. The moving sheet of water drains into a reservoir and, during recirculation through the sampler, is passed through an XAD-2 resin column which adsorbs the trapped organic contaminants. All surfaces which contact the process water are stainless steel or Teflon. Chemicals collected can be related to airborne materials depositing into aquatic ecosystems. The sampler has received a United States patent (number 5,413,003 - 9 May 1996) with the Canadian patent pending. XAD-2 resin adsorption efficiencies for 10 or 50 μg fortifications of ten pesticides ranged from 76% for atrazine (2-chloro-4-ethylamino-6-isopropylamino- S-triazine) to 110% for triallate [ S-(2,3,3-trichloro-2-phenyl)bis(1-methylethyl)carbamothioate], dicamba (2-methoxy-3,6-dichlorobenzoic acid) and toxaphene (chlorinated camphene mixture). Field testing using duplicate samplers showed good reproducibility and amounts trapped were consistent with those from high volume and bulk pan samplers located on the same site. Average atmospheric dry deposition rates of three chemicals, collected for 5 weeks in May and June, were: dicamba, 69 ng m -2 da -1; 2,4-D (2,4-dichlorophenoxyacetic acid), 276 ng m -2 da -1: and, γ-HCH ( γ-1, 2, 3, 4, 5, 6-hexachlorocyclohexane), 327 ng m -2 da -1.

  12. Extraction of Aerosol-Deposited Yersinia pestis from Indoor Surfaces To Determine Bacterial Environmental Decay

    PubMed Central

    Bartlett, Ryan A.; Yeager, John J.; Leroux, Brian; Ratnesar-Shumate, Shanna; Dabisch, Paul

    2016-01-01

    ABSTRACT Public health and decontamination decisions following an event that causes indoor contamination with a biological agent require knowledge of the environmental persistence of the agent. The goals of this study were to develop methods for experimentally depositing bacteria onto indoor surfaces via aerosol, evaluate methods for sampling and enumerating the agent on surfaces, and use these methods to determine bacterial surface decay. A specialized aerosol deposition chamber was constructed, and methods were established for reproducible and uniform aerosol deposition of bacteria onto four coupon types. The deposition chamber facilitated the control of relative humidity (RH; 10 to 70%) following particle deposition to mimic the conditions of indoor environments, as RH is not controlled by standard heating, ventilation, and air conditioning (HVAC) systems. Extraction and culture-based enumeration methods to quantify the viable bacteria on coupons were shown to be highly sensitive and reproducible. To demonstrate the usefulness of the system for decay studies, Yersinia pestis persistence as a function of surface type at 21°C and 40% RH was determined to be >40%/min for all surfaces. Based upon these results, at typical indoor temperature and RH, a 6-log reduction in titer would expected to be achieved within 1 h as the result of environmental decay on surfaces without active decontamination. The developed approach will facilitate future persistence and decontamination studies with a broad range of biological agents and surfaces, providing agent decay data to inform both assessments of risk to personnel entering a contaminated site and decontamination decisions following biological contamination of an indoor environment. IMPORTANCE Public health and decontamination decisions following contamination of an indoor environment with a biological agent require knowledge of the environmental persistence of the agent. Previous studies on Y. pestis persistence have

  13. Contribution of airborne microbes to bacterial production and N2 fixation in seawater upon aerosol deposition

    NASA Astrophysics Data System (ADS)

    Rahav, Eyal; Ovadia, Galit; Paytan, Adina; Herut, Barak

    2016-01-01

    Aerosol deposition may supply a high diversity of airborne microbes, which can affect surface microbial composition and biological production. This study reports a diverse microbial community associated with dust and other aerosol particles, which differed significantly according to their geographical air mass origin. Microcosm bioassay experiments, in which aerosols were added to sterile (0.2 µm filtered and autoclaved) SE Mediterranean Sea (SEMS) water, were performed to assess the potential impact of airborne bacteria on bacterial abundance, production, and N2 fixation. Significant increase was observed in all parameters within a few hours, and calculations suggest that airborne microbes can account for one third in bacterial abundance and 50-100% in bacterial production and N2-fixation rates following dust/aerosol amendments in the surface SEMS. We show that dust/aerosol deposition can be a potential source of a wide array of microorganisms, which may impact microbial composition and food web dynamics in oligotrophic marine systems such as the SEMS.

  14. Influence of anthropogenic aerosol deposition on the relationship between oceanic productivity and warming

    PubMed Central

    Balkanski, Yves; Bopp, Laurent; Aumont, Olivier; Boucher, Olivier; Ciais, Philippe; Gehlen, Marion; Peñuelas, Josep; Ethé, Christian; Hauglustaine, Didier; Li, Bengang; Liu, Junfeng; Zhou, Feng; Tao, Shu

    2015-01-01

    Abstract Satellite data and models suggest that oceanic productivity is reduced in response to less nutrient supply under warming. In contrast, anthropogenic aerosols provide nutrients and exert a fertilizing effect, but its contribution to evolution of oceanic productivity is unknown. We simulate the response of oceanic biogeochemistry to anthropogenic aerosols deposition under varying climate from 1850 to 2010. We find a positive response of observed chlorophyll to deposition of anthropogenic aerosols. Our results suggest that anthropogenic aerosols reduce the sensitivity of oceanic productivity to warming from −15.2 ± 1.8 to −13.3 ± 1.6 Pg C yr−1 °C−1 in global stratified oceans during 1948–2007. The reducing percentage over the North Atlantic, North Pacific, and Indian Oceans reaches 40, 24, and 25%, respectively. We hypothesize that inevitable reduction of aerosol emissions in response to higher air quality standards in the future might accelerate the decline of oceanic productivity per unit warming. PMID:27867233

  15. Influence of anthropogenic aerosol deposition on the relationship between oceanic productivity and warming.

    PubMed

    Wang, Rong; Balkanski, Yves; Bopp, Laurent; Aumont, Olivier; Boucher, Olivier; Ciais, Philippe; Gehlen, Marion; Peñuelas, Josep; Ethé, Christian; Hauglustaine, Didier; Li, Bengang; Liu, Junfeng; Zhou, Feng; Tao, Shu

    2015-12-28

    Satellite data and models suggest that oceanic productivity is reduced in response to less nutrient supply under warming. In contrast, anthropogenic aerosols provide nutrients and exert a fertilizing effect, but its contribution to evolution of oceanic productivity is unknown. We simulate the response of oceanic biogeochemistry to anthropogenic aerosols deposition under varying climate from 1850 to 2010. We find a positive response of observed chlorophyll to deposition of anthropogenic aerosols. Our results suggest that anthropogenic aerosols reduce the sensitivity of oceanic productivity to warming from -15.2 ± 1.8 to -13.3 ± 1.6 Pg C yr(-1) °C(-1) in global stratified oceans during 1948-2007. The reducing percentage over the North Atlantic, North Pacific, and Indian Oceans reaches 40, 24, and 25%, respectively. We hypothesize that inevitable reduction of aerosol emissions in response to higher air quality standards in the future might accelerate the decline of oceanic productivity per unit warming.

  16. Impact of Air Pollution on Mineral Aerosol Deposition, Soluble Fe Flux and Ocean Biogeochemistry

    NASA Astrophysics Data System (ADS)

    Levy, H.

    2006-12-01

    We find that a two-step mechanism (sulfate and nitrate coating followed by hematite dissolution) is necessary to reproduce observations of mineral aerosol iron solubility that range from less than 1% over desert source regions to frequently more than 10% in the remote Pacific and Atlantic. This mechanism was implemented in a global atmospheric model of dust entrainment, transport, dissolution, and deposition that simulates a realistic distribution of mineral aerosol. Model simulations with pre-industrial and present levels of pollution are presented. Analysis shows that, while atmospheric pollution results in a slight decrease in mineral aerosol lifetime and lower dust concentrations over the remote oceans, it also appreciably increases the rate of hematite dissolution in the dust that remains airborne and results in a significant increase in the percent solubility of deposited iron. The net result of anthropogenic emissions of SO2 and NOx is increased oceanic deposition of soluble iron, particularly to the Northern Hemisphere oceans. These new soluble iron deposition fields are then used as input to an ocean biogeochemistry model. We first compare results from two complex ocean biogeochemistry model simulations using: 1. Fe fluxes based on previous global model approaches of constant solubility; 2. Fe fluxes of variable iron solubility from this study. We then examine the implications of the pollution driven increases in iron deposition to ocean ecosystems and to iron cycling in the surface ocean, particularly in the Subarctic and Equatorial Pacific where primary productivity is known to be stressed by low iron availability.

  17. Aerodynamics and deposition effects of inhaled submicron drug aerosol in airway diseases.

    PubMed

    Faiyazuddin, Md; Mujahid, Md; Hussain, Talib; Siddiqui, Hefazat H; Bhatnagar, Aseem; Khar, Roop K; Ahmad, Farhan J

    2013-01-01

    Particle engineering is the prime focus to improve pulmonary drug targeting with the splendor of nanomedicines. In recent years, submicron particles have emerged as prettyful candidate for improved fludisation and deposition. For effective deposition, the particle size must be in the range of 0.5-5 μm. Inhalers design for the purpose of efficient delivery of powders to lungs is again a crucial task for pulmonary scientists. A huge number of DPI devices exist in the market, a significant number are awaiting FDA approval, some are under development and a large number have been patented or applied for patent. Even with superior design, the delivery competence is still deprived, mostly due to fluidisation problems which cause poor aerosol generation and deposition. Because of the cohesive nature and poor flow characteristics, they are difficult to redisperse upon aerosolization with breath. These problems are illustrious in aerosol research, much of which is vastly pertinent to pulmonary therapeutics. A technical review is presented here of advances that have been utilized in production of submicron drug particles, their in vitro/in vivo evaluations, aerosol effects and pulmonary fate of inhaled submicron powders.

  18. Analysis of Three-Dimensional Aerosol Deposition in Pharmacologically Relevant Terms: Beyond Black or White ROIs

    PubMed Central

    Greenblatt, Elliot Eliyahu; Winkler, Tilo; Harris, Robert Scott; Kelly, Vanessa Jane; Kone, Mamary

    2015-01-01

    Abstract Background: This article presents a novel methodological approach to evaluate images of aerosol deposition taken with PET-CT cameras. Traditionally, Black-or-White (BW) Regions of Interest (ROIs) are created to cover Anatomical Regions (ARs) segmented from the high-resolution CT. Such ROIs do not usually consider blurring effects due to limited spatial resolution or breathing motion, and do not consider uncertainty in the AR position within the PET image. The new methodology presented here (Grayscale) addresses these issues, allows estimates of aerosol deposition within ARs, and expresses the deposition in terms of Tissue Dosing (in the lung periphery) and Inner Surface Concentration (in the larger airways). Methods: Imaging data included a PET deposition image acquired during breathing and two CT scans acquired during breath holds at different lung volumes. The lungs were segmented into anatomically consistent ARs to allow unbiased comparisons across subjects and across lobes. The Grayscale method involves defining Voxel Influence Matrices (VIMs) to consider how average activity within each AR influences the measured activity within each voxel. The BW and Grayscale methods were used to analyze aerosol deposition in 14 bronchoconstricted asthmatics. Results: Grayscale resulted in a closer description of the PET image than BW (p<0.0001) and exposed a seven-fold underestimation in measures of specific deposition. The Average Tissue Dosing was 2.11×10−6 Total Lung Dose/mg. The average Inner Surface Concentration was 45×10−6 Total Lung Dose/mm2, with the left lower lobe having a lower ISC than lobes of the right lung (p<0.05). There was a strong lobar heterogeneity in these measures (COV=0.3). Conclusion: The Grayscale approach is an improvement over the BW approach and provides a closer description of the PET image. It can be used to characterize heterogeneous concentrations throughout the lung and may be important in translational research and in the

  19. Factors determining pulmonary deposition of aerosolized pentamidine in patients with human immunodeficiency virus infection

    SciTech Connect

    Smaldone, G.C.; Fuhrer, J.; Steigbigel, R.T.; McPeck, M. )

    1991-04-01

    Although aerosolized pentamidine (AP) has recently been approved for prophylaxis and is undergoing clinical trials for treatment of pneumocystis, pneumonia (PCP), factors important in the deposition of AP have not been described. Using radioaerosol techniques, deposition was measured in 22 patients receiving AP for prophylaxis or treatment of PCP. In all patients total and regional deposition of pentamidine, breathing pattern, pulmonary function (PFT), regional ventilation, and type of nebulizer were analyzed. Bronchoalveolar lavage (BAL) was performed 24 h after inhalation to assess the relationship between pentamidine levels in BAL fluid and measured aerosol deposition. The nebulizers tested were the Marquest Respirgard II and the Cadema AeroTech II, both previously characterized in our laboratory. The aerosol particles consist of water droplets containing dissolved pentamidine and technetium 99m bound to albumin. Analysis of particles sampled during inhalation via cascade impaction confirmed a close relationship between radioactivity in the droplets and the concentration of pentamidine as measured by HPLC (r = 0.971, p less than 0.0001; n = 18). Deposition was measured by capturing inhaled and exhaled particles on absolute filters and measuring radioactivity. This technique allows the determination of the deposition fraction (DF, the fraction of the amount inhaled that is deposited), which provides information on factors strictly related to the patient. To confirm the filter measurements, pentamidine deposition was also measured by gamma camera. The camera measurement was possible because each patient's thoracic attenuation of radioactivity was determined by a quantitative perfusion scan. Regional lung volume and ventilation were determined by xenon 133 equilibrium scan and washout.

  20. Diffusive deposition of aerosols in Phebus containment during FPT-2 test

    SciTech Connect

    Kontautas, A.; Urbonavicius, E.

    2012-07-01

    At present the lumped-parameter codes is the main tool to investigate the complex response of the containment of Nuclear Power Plant in case of an accident. Continuous development and validation of the codes is required to perform realistic investigation of the processes that determine the possible source term of radioactive products to the environment. Validation of the codes is based on the comparison of the calculated results with the measurements performed in experimental facilities. The most extensive experimental program to investigate fission product release from the molten fuel, transport through the cooling circuit and deposition in the containment is performed in PHEBUS test facility. Test FPT-2 performed in this facility is considered for analysis of processes taking place in containment. Earlier performed investigations using COCOSYS code showed that the code could be successfully used for analysis of thermal-hydraulic processes and deposition of aerosols, but there was also noticed that diffusive deposition on the vertical walls does not fit well with the measured results. In the CPA module of ASTEC code there is implemented different model for diffusive deposition, therefore the PHEBUS containment model was transferred from COCOSYS code to ASTEC-CPA to investigate the influence of the diffusive deposition modelling. Analysis was performed using PHEBUS containment model of 16 nodes. The calculated thermal-hydraulic parameters are in good agreement with measured results, which gives basis for realistic simulation of aerosol transport and deposition processes. Performed investigations showed that diffusive deposition model has influence on the aerosol deposition distribution on different surfaces in the test facility. (authors)

  1. In vivo deposition of ultrafine aerosols in human nasal and oral airways

    SciTech Connect

    Yeh, Hsu-Chi; Swift, D.L.; Simpson, S.Q.

    1995-12-01

    The extrathoracic airways, including the nasal passage, oral passage, pharynx, and larynx, are the first targets for inhaled particles and provide an important defense for the lung. Understanding the deposition efficiency of the nasal and oral passages is therefore crucial for assessing doses of inhaled particles to the extrathoracic airways and the lung. Significant inter-subject variability in nasal deposition has been shown in recent studies by Rasmussen, T.R. et al, using 2.6 {mu}m particles in 10 human subjects and in our preliminary studies using 0.004-0.15 {mu}m particles in four adult volunteers. No oral deposition was reported in either of these studies. Reasons for the intersubject variations have been frequently attributed to the geometry of the nasal passages. The aims of the present study were to measure in vivo the nasal airway dimensions and the deposition of ultrafine aerosols in both the nasal and oral passages, and to determine the relationship between nasal airway dimensions and aerosol deposition. A statistical procedure incorporated with the diffusion theory was used to model the dimensional features of the nasal airways which may be responsible for the biological variability in particle deposition. In summary, we have correlated deposition of particles in the size range of 0.004 to 0.15 {mu}m with the nasal dimensions of each subject.

  2. A Review of Spatial Variation of Inorganic Nitrogen (N) Wet Deposition in China

    PubMed Central

    Liu, Lei; Zhang, Xiuying; Wang, Shanqian; Lu, Xuehe; Ouyang, Xiaoying

    2016-01-01

    Atmospheric nitrogen (N) deposition (Ndep), an important component of the global N cycle, has increased sharply in recent decades in China. Although there were already some studies on Ndep on a national scale, there were some gaps on the magnitude and the spatial patterns of Ndep. In this study, a national-scale Ndep pattern was constructed based on 139 published papers from 2003 to 2014 and the effects of precipitation (P), energy consumption (E) and N fertilizer use (FN) on spatial patterns of Ndep were analyzed. The wet deposition flux of NH4+-N, NO3--N and total Ndep was 6.83, 5.35 and 12.18 kg ha-1 a-1, respectively. Ndep exhibited a decreasing gradient from southeast to northwest of China. Through accuracy assessment of the spatial Ndep distribution and comparisons with other studies, the spatial Ndep distribution by Lu and Tian and this study both gained high accuracy. A strong exponential function was found between P and Ndep, FN and Ndep and E and Ndep, and P and FN had higher contribution than E on the spatial variation of Ndep. Fossil fuel combustion was the main contributor for NO3--N (86.0%) and biomass burning contributed 5.4% on the deposition of NO3--N. The ion of NH4+ was mainly from agricultural activities (85.9%) and fossil fuel combustion (6.0%). Overall, Ndep in China might be considerably affected by the high emissions of NOx and NH3 from fossil fuel combustion and agricultural activities. PMID:26731264

  3. AEROSOL TRANSPORT AND DEPOSITION IN SEQUENTIALLY BIFURCATING AIRWAYS

    EPA Science Inventory

    Deposition patterns and efficiencies of a dilute suspension of inhaled particles in three-dimensional double bifurcating airway models for both in-plane and 90 deg out-of-plane configurations have been numerically simulated assuming steady, laminar, constant-property air flow wit...

  4. A gas exchange system to study the effects of leaf surface wetness on the deposition of ozone

    NASA Astrophysics Data System (ADS)

    Fuentes, J. D.; Gillespie, T. J.

    A leaf chamber system has been developed for measuring the uptake of ozone (O 3) by whole plant leaves artificially wetted with dew or raindrops. Tests showed negligible amounts of O 3 being lost on internal walls of the chamber, and good heat and mass transfer characteristics without the use of internal mixing fans. The system enables easy and accurate determination of pollutant uptake by wet and dry foliage. Measurements of O 3 fluxes to individual leaves indicate that leaf surface wetness, either in the form of a dew layer or raindrops, on the adaxial surface of hypostomatous red maple leaves, enhances the deposition of O 3. The increased O 3 deposition is ascribed mainly to the presence of compounds in aqueous form that readily scavenge O 3, with a lesser additional contribution from decreased stomatal resistance to O 3 diffusion.

  5. Spatial Variability of Mercury Wet Deposition in Eastern Ohio: Summertime Meteorological Case Study Analysis of Local Source Influences

    EPA Science Inventory

    Extensive exploration of event precipitation data in the Ohio River Valley indicates that coal combustion emissions play an important role in mercury (Hg) wet deposition. During July-September 2006, an intensive study was undertaken to discern the degree of local source influence...

  6. Investigating the impact of local urban sources on total atmospheric mercury wet deposition in Cleveland, Ohio, USA

    EPA Science Inventory

    Event-based precipitation samples were collected at a downtown industrial and a predominantly upwind rural location in the Cleveland, Ohio metropolitan area from July 2009 through December 2010 to investigate the potential local total mercury (Hg) wet deposition enhancement in a ...

  7. Antibacterial and water purification activities of self-assembled honeycomb structure of aerosol deposited titania film.

    PubMed

    Park, Jung-Jae; Lee, Jong-Gun; Kim, Do-Yeon; Hong, Joo-Hyun; Kim, Jae-Jin; Hong, Seungkwan; Yoon, Sam S

    2012-11-20

    A simple and rapid room-temperature aerosol deposition method was used to fabricate TiO(2) films for photokilling/photdegradation applications. TiO(2) particles were accelerated to supersonic speeds and fractured upon impacting a glass substrate to form a functional thin film, a process known as aerosol deposition. After deposition, the films were annealed at various temperatures, and their photokilling/photodegradation performances following ultraviolet (UV) exposure were evaluated by counting the number of surviving bacterial colonies, and by a methylene blue decolorization test. The photocatalytic performances of all TiO(2) films were obtained under weak UV exposure (0.6 mW/cm(2)). The film density, crystalline phase, and surface roughness (morphology) were measured by scanning electron microscopy, X-ray diffraction, UV-visible spectroscopy, and atomic force microscopy. The unique, self-assembled honeycomb structure of the aerosol deposited films contributed to the increase in surface area because of extreme roughness, which enhances the photokilling and photodegradation performance. Nonannealed films yielded the best photocatalytic performance due to their small crystalline sizes and large surface areas due to increased surface roughness.

  8. Aerosol delivery of amphotericin B desoxycholate (Fungizone) and liposomal amphotericin B (AmBisome): aerosol characteristics and in-vivo amphotericin B deposition in rats.

    PubMed

    Ruijgrok, E J; Vulto, A G; Van Etten, E W

    2000-06-01

    In the treatment or prophylaxis of invasive pulmonary aspergillosis, it may be attractive to administer the antifungal agent amphotericin directly to the pulmonary route via aerosol inhalation. In this study, we describe the aerosol characteristics of aerosolized nonliposomal amphotericin B (Fungizone) and liposomal amphotericin B (AmBisome), and the in-vivo aerosol deposition. Aerosols were generated with a Collison nebulizer. Aerosol amphotericin concentrations and mass median diameters were measured. In-vivo pulmonary deposition was evaluated by measuring amphotericin concentrations in lungs of treated rats. Whole body aerosol deposition was determined by measuring radioactivity in tissues of rats after treatment with radiolabelled liposomes. For Fungizone and AmBisome, aerosol amphotericin concentrations were 24.5+/-4.9 and 23.8+/-3.0 microg L(-1), respectively. The values for the median mass diameter were 1.38 and 2.26 microm for Fungizone and 2.43 and 1.97 microm for AmBisome. Amphotericin concentrations in lungs after 60-min nebulization of Fungizone or AmBisome were 24.2+/-6.4 and 21.7+/-2.6 microg g(-1), respectively. After nebulization of radiolabelled liposomes, no radioactivity was retrieved from tissues other than the lungs or the gastrointestinal tract. Nebulization of either Fungizone or AmBisome leads to respirable aerosols and results in a substantial lung tissue concentration of amphotericin and low systemic exposure of amphotericin B. Aerosol administration of either Fungizone or AmBisome may be an attractive approach to prevent or treat pulmonary aspergillosis.

  9. The precision of wet atmospheric deposition data from national atmospheric deposition program/national trends network sites determined with collocated samplers

    USGS Publications Warehouse

    Nilles, M.A.; Gordon, J.D.; Schroder, L.J.

    1994-01-01

    A collocated, wet-deposition sampler program has been operated since October 1988 by the U.S. Geological Survey to estimate the overall sampling precision of wet atmospheric deposition data collected at selected sites in the National Atmospheric Deposition Program and National Trends Network (NADP/NTN). A duplicate set of wet-deposition sampling instruments was installed adjacent to existing sampling instruments at four different NADP/NTN sites for each year of the study. Wet-deposition samples from collocated sites were collected and analysed using standard NADP/NTN procedures. Laboratory analyses included determinations of pH, specific conductance, and concentrations of major cations and anions. The estimates of precision included all variability in the data-collection system, from the point of sample collection through storage in the NADP/NTN database. Sampling precision was determined from the absolute value of differences in the analytical results for the paired samples in terms of median relative and absolute difference. The median relative difference for Mg2+, Na+, K+ and NH4+ concentration and deposition was quite variable between sites and exceeded 10% at most sites. Relative error for analytes whose concentrations typically approached laboratory method detection limits were greater than for analytes that did not typically approach detection limits. The median relative difference for SO42- and NO3- concentration, specific conductance, and sample volume at all sites was less than 7%. Precision for H+ concentration and deposition ranged from less than 10% at sites with typically high levels of H+ concentration to greater than 30% at sites with low H+ concentration. Median difference for analyte concentration and deposition was typically 1.5-2-times greater for samples collected during the winter than during other seasons at two northern sites. Likewise, the median relative difference in sample volume for winter samples was more than double the annual median

  10. Sea salt aerosol deposition in the coastal zone: A large eddy simulation study

    NASA Astrophysics Data System (ADS)

    Liang, Tinghao; Chamecki, Marcelo; Yu, Xiping

    2016-11-01

    Inland deposition of sea salt aerosol (SSA) particles emitted over the ocean is studied via numerical and theoretical models. The focus is on the large particles that contribute most to the total mass deposition. Large eddy simulations of idealized sea wind are used to investigate the development of the particle plume over land for different particle sizes and to validate some of the assumptions in the theoretical model. An existing theoretical modeling framework for particle dispersion in the atmospheric boundary layer is adapted to the problem of SSA deposition and it is shown to be adequate for the large particles of interest here. The decay of monodisperse SSA particle deposition flux with distance from the shoreline is shown to have a power-law behavior far from the shoreline. A complete model for predicting mass deposition as a function of distance is formulated and shown to present reasonable agreement with existing data.

  11. Fabrication of bimetallic nanostructures via aerosol-assisted electroless silver deposition for catalytic CO conversion.

    PubMed

    Byeon, Jeong Hoon; Kim, Jang-Woo

    2014-03-12

    Bimetallic nanostructures were fabricated via aerosol-assisted electroless silver deposition for catalytic CO conversion. An ambient spark discharge was employed to produce nanocatalysts, and the particles were directly deposited on a polytetrafluoroethylene substrate for initiating silver deposition to form Pd-Ag, Pt-Ag, Au-Ag bimetallic nanostructures as well as a pure Ag nanostructure. Kinetics and morphological evolutions in the silver deposition with different nanocatalysts were comparatively studied. The Pt catalyst displayed the highest catalytic activity for electroless silver deposition, followed by the order Pd > Au > Ag. Another catalytic activity of the fabricated bimetallic structures in the carbon monoxide conversion was further evaluated at low-temperature conditions. The bimetallic systems showed significantly higher catalytic activity than that from a pure Ag system.

  12. Investigating the impact of local urban sources on total atmospheric mercury wet deposition in Cleveland, Ohio, USA

    NASA Astrophysics Data System (ADS)

    Lynam, Mary M.; Dvonch, J. Timothy; Barres, James A.; Landis, Matthew S.; Kamal, Ali S.

    2016-02-01

    Event-based precipitation samples were collected at a downtown industrial and a predominantly upwind rural location in the Cleveland, Ohio metropolitan area from July 2009 through December 2010 to investigate the potential local total mercury (Hg) wet deposition enhancement in a region with a high concentration of coal combustion sources. Total Hg wet deposition for the 18-month period was 6.8 μg m-2 (n = 81) at the rural site and 10.7 μg m-2 (n = 98) at the urban site demonstrating a significant (p = 0.046) 37% enhancement in deposition between the two sites. Large deposition events (>0.2 μg m-2) occurred predominantly from May through October (n = 16 (urban), n = 10 (rural)) and represented from 2 to 8% of total 18-month deposition per event. At the downtown urban site, the average Hg precipitation concentration was 53% higher for these large deposition events. Concurrently measured precipitation events delivered in aggregate 2.4 times more total Hg wet deposition to the urban site compared to the rural site. Hg rainfall concentrations for concurrent events with similar precipitation depth were 2-4 times higher at the urban site and suggest scavenging of local Hg emissions. Further evaluation of these events revealed 83% more total Hg deposition at the urban site from January to December 2010 compared to July to December 2009, while there was 26% more at the rural site during these same time periods. The larger increase in deposition at the urban site in 2010 may be evidence of increased local emissions from sources that were known to be offline during this study period because of an economic recession.

  13. Sensitivity of the modelled deposition of Caesium-137 from the Fukushima Dai-ichi nuclear power plant to the wet deposition parameterisation in NAME.

    PubMed

    Leadbetter, Susan J; Hort, Matthew C; Jones, Andrew R; Webster, Helen N; Draxler, Roland R

    2015-01-01

    This paper describes an investigation into the impact of different meteorological data sets and different wet scavenging coefficients on the model predictions of radionuclide deposits following the accident at the Fukushima Dai-ichi nuclear power plant in March 2011. Three separate operational meteorological data sets, the UK Met Office global meteorology, the ECMWF global meteorology and the Japan Meteorological Agency (JMA) mesoscale meteorology as well as radar rainfall analyses from JMA were all used as inputs to the UK Met Office's dispersion model NAME (the Numerical Atmospheric-dispersion Modelling Environment). The model predictions of Caesium-137 deposits based on these meteorological models all showed good agreement with observations of deposits made in eastern Japan with correlation coefficients ranging from 0.44 to 0.80. Unexpectedly the NAME run using radar rainfall data had a lower correlation coefficient (R = 0.66), when compared to observations, than the run using the JMA mesoscale model rainfall (R = 0.76) or the run using ECMWF met data (R = 0.80). Additionally the impact of modifying the wet scavenging coefficients used in the parameterisation of wet deposition was investigated. The results showed that modifying the scavenging parameters had a similar impact to modifying the driving meteorology on the rank calculated from comparing the modelled and observed deposition.

  14. Development of the aerosol generation system for simulating the dry deposition behavior of radioaerosol emitted by the accident of FDNPP

    NASA Astrophysics Data System (ADS)

    Zhang, Z.

    2015-12-01

    A large amount of radioactivity was discharged by the accident of FDNPP. The long half-life radionuclide, 137Cs was transported through the atmosphere mainly as the aerosol form and deposited to the forests in Fukushima prefecture. After the dry deposition of the 137Cs, the foliar uptake process would occur. To evaluate environmental transfer of radionuclides, the dry deposition and following foliar uptake is very important. There are some pioneering studies for radionuclide foliar uptake with attaching the solution containing stable target element on the leaf, however, cesium oxide aerosols were used for these deposition study [1]. In the FDNPP case, 137Cs was transported in sulfate aerosol form [2], so the oxide aerosol behaviors could not represent the actual deposition behavior in this accident. For evaluation of whole behavior of 137Cs in vegetation system, fundamental data for deposition and uptake process of sulfate aerosol was desired. In this study, we developed aerosol generation system for simulating the dry deposition and the foliar uptake behaviors of aerosol in the different chemical constitutions. In this system, the method of aerosol generation based on the spray drying. Solution contained 137Cs was send to a nozzle by a syringe pump and spraying with a high speed air flow. The sprayed mist was generated in a chamber in the relatively high temperature. The solution in the mist was dried quickly, and micro size solid aerosols consisting 137Cs were generated. The aerosols were suctioned by an ejector and transported inside a tube by the dry air flow, then were directly blown onto the leaves. The experimental condition, such as the size of chamber, chamber temperature, solution flow rate, air flow rate and so on, were optimized. In the deposition experiment, the aerosols on leaves were observed by a SEM/EDX system and the deposition amount was evaluated by measuring the stable Cs remaining on leaf. In the presentation, we will discuss the detail

  15. A comparative sensitivity analysis focused on wet deposition models for the Fukushima and Chernobyl atmospheric dispersion events

    NASA Astrophysics Data System (ADS)

    Quérel, Arnaud; Roustan, Yelva; Quélo, Denis; Bocquet, Marc; Winiarek, Victor

    2014-05-01

    In order to model the transport of radionuclides bound to atmospheric particles and the ground contamination at the synoptic scale, the wet deposition is a crucial point. Usually, the wet deposition is divided in two different mechanisms, the below-cloud scavenging (washout) and the in-cloud scavenging (rainout). Since the micro-physics of both deposition processes is not well known yet, the modeling of the wet deposition of particles at the synoptic scale is uncertain and difficult to validate. This leads to an abundance of wet deposition models, none of them being fully adequate. The existing models of particle scavenging can be distinguished by the nature and the number of physical parameters they rely on. For instance the scavenging coefficient variability can be determined only by the rainfall intensity or take into account the rainfall intensity and the particle size distribution. Beyond their intrinsic formulations, the deposition models are sensitive to the input data necessary to use them, cloud height for instance. Finally, the simulated ground deposition is more or less sensitive to the choices of the overall-models involved in the atmospheric transport of particles and the meteorology in general. For accidental atmospheric releases, the uncertainties linked to the source-term are for instance crucial, what justifies the use of different ones in the study. The Polyphemus air quality system is used to perform the simulations of the radioactive dispersion, considering Caesium-137 as particulate matter for the accidental releases from the Fukushima and Chernobyl nuclear power plants. In this study, two different approaches are used. In the first one, the influence of the different components taking part in the scavenging modeling are confronted separately (whether the scavenging models or the overall models). The second approach is a global sensitivity analysis computed both on the Chernobyl and Fukushima cases. It relies on simulations performed with

  16. Aerosol-assisted plasma deposition of hydrophobic polycations makes surfaces highly antimicrobial.

    PubMed

    Liu, Harris; Kim, Yoojeong; Mello, Kerrianne; Lovaasen, John; Shah, Apoorva; Rice, Norman; Yim, Jacqueline H; Pappas, Daphne; Klibanov, Alexander M

    2014-02-01

    The currently used multistep chemical synthesis for making surfaces antimicrobial by attaching to them hydrophobic polycations is replaced herein by an aerosol-assisted plasma deposition procedure. To this end, N,N-hexyl,methyl-PEI (HMPEI) is directly plasma-coated onto a glass surface. The resultant immobilized HMPEI coating has been thoroughly characterized and shown to be robust, bactericidal against Escherichia coli, and virucidal against human influenza virus.

  17. Quantitative assessment of inhalation exposure and deposited dose of aerosol from nanotechnology-based consumer sprays†

    PubMed Central

    Nazarenko, Yevgen; Lioy, Paul J.; Mainelis, Gediminas

    2015-01-01

    This study provides a quantitative assessment of inhalation exposure and deposited aerosol dose in the 14 nm to 20 μm particle size range based on the aerosol measurements conducted during realistic usage simulation of five nanotechnology-based and five regular spray products matching the nano-products by purpose of application. The products were also examined using transmission electron microscopy. In seven out of ten sprays, the highest inhalation exposure was observed for the coarse (2.5–10 μm) particles while being minimal or below the detection limit for the remaining three sprays. Nanosized aerosol particles (14–100 nm) were released, which resulted in low but measurable inhalation exposures from all of the investigated consumer sprays. Eight out of ten products produced high total deposited aerosol doses on the order of 101–103 ng kg−1 bw per application, ~85–88% of which were in the head airways, only <10% in the alveolar region and <8% in the tracheobronchial region. One nano and one regular spray produced substantially lower total deposited doses (by 2–4 orders of magnitude less), only ~52–64% of which were in the head while ~29–40% in the alveolar region. The electron microscopy data showed nanosized objects in some products not labeled as nanotechnology-based and conversely did not find nano-objects in some nano-sprays. We found no correlation between nano-object presence and abundance as per the electron microscopy data and the determined inhalation exposures and deposited doses. The findings of this study and the reported quantitative exposure data will be valuable for the manufacturers of nanotechnology-based consumer sprays to minimize inhalation exposure from their products, as well as for the regulators focusing on protecting the public health. PMID:25621175

  18. Comparison of jet and ultrasonic nebulizer pulmonary aerosol deposition during mechanical ventilation.

    PubMed

    Harvey, C J; O'Doherty, M J; Page, C J; Thomas, S H; Nunan, T O; Treacher, D F

    1997-04-01

    Increased delivery of aerosol to a model lung (attached to a mechanical ventilator) has been demonstrated with an ultrasonic nebulizer as compared to a jet nebulizer. This study examined whether the increased aerosol deposition with an ultrasonic nebulizer could also be demonstrated in vivo. Seven patients (6 male and 1 female) were studied during mechanical ventilalion (Siemens Servo 900C, Middlesex, UK) after open heart surgery. Two studies were performed in each patient. In the first study, aerosol was delivered via a Siemens Servo 945 nebulizer system (high setting) driving a System 22 Acorn jet nebulizer (Medic-Aid, Sussex, UK) containing 3 mL (99m)technetium-labelled human serum albumin (99mTc-HSA) (50 microg; activity 74 MBq). In the second study, a DP100 ultrasonic nebulizer (DP Medical, Meylan, France) containing 12 mL 99mTc-HSA (50 microg; activity 185 MBq) was used. Pulmonary deposition was quantified using a gamma camera. The humidification of the circuit and the ventilator settings were kept constant according to the patient's clinical requirements. The total lung aerosol deposition (mean+/-SD), as a percentage of initial nebulizer activity, was greater using the ultrasonic nebulizer than using the jet nebulizer (53+/-1.4 vs 2.3+/-0.9%; p<0.002). The ultrasonic nebulizer was also associated with a reduction in the time required to complete nebulization (9 vs 21 min, respectively) (p<0.0001). Use of the DP100 ultrasonic nebulizer more than doubled lung deposition compared with the System 22 jet nebulizers in mechanically-ventilated patients. Their efficiency, speed of drug delivery, and compatibility with mechanical ventilator circuits make ultrasonic nebulizers potentially attractive for use during mechanical ventilation.

  19. Atmospheric wet deposition of nitrogen and sulfur in the agroecosystem in developing and developed areas of Southeastern China

    NASA Astrophysics Data System (ADS)

    Cui, Jian; Zhou, Jing; Peng, Ying; He, Yuanqiu; Yang, Hao; Mao, Jingdong; Zhang, Mingli; Wang, Yanhua; Wang, Shuwei

    2014-06-01

    Atmospheric nitrogen (N) and sulfur (S) deposition is a significant and growing issue for ecological environment in many parts of the world such as China. However, the study on atmospheric deposition, especially N deposition, is still at the initial stage and usually neglected in agro-ecosystems. To assess the characteristics of N and S wet deposition in agro-ecosystems, we selected Yingtan Station (YTS) located in the developing area and Changshu Station (CSS) in the developed area as typical, agricultural study sites in Southeastern China during 2010-2011. In the two areas, the total N and S wet deposition were in ranges of 30.49-37.37 kg ha-1 year-1 N and 56.02-59.06 kg ha-1 year-1 S, respectively, surpassing their corresponding critical loads in China. The annual means of NH4+-N, NO3--N and dissolved organic N (DON) deposition contributed 49.6%, 26.4% and 24.0% of the total deposition, respectively. Similar total N and S deposition data were observed in the two sites, but their N species, especially DON, were different due to different numbers of slaughter pigs and types of N fertilizers applied. In conclusion, DON was identified as an important contributor to the total N deposition and should also be monitored in the future. Such high N and S deposition would deteriorate agroecosystems in Southeastern China. Related political measures on livestock industries, managements of motor vehicles and technologies of coal and oil combustion should be improved timely and implemented effectively for reducing the regional N emission and deposition in the future.

  20. Wet and dry deposition of mineral dust particles in Japan: factors related to temporal variation and spatial distribution

    NASA Astrophysics Data System (ADS)

    Osada, K.; Ura, S.; Kagawa, M.; Mikami, M.; Tanaka, T. Y.; Matoba, S.; Aoki, K.; Shinoda, M.; Kurosaki, Y.; Hayashi, M.; Shimizu, A.; Uematsu, M.

    2014-01-01

    Recent ground networks and satellite remote-sensing observations have provided useful data related to spatial and vertical distributions of mineral dust particles in the atmosphere. However, measurements of temporal variations and spatial distributions of mineral dust deposition fluxes are limited in terms of their duration, location, and processes of deposition. To ascertain temporal variations and spatial distributions of mineral dust deposition using wet and dry processes, weekly deposition samples were obtained at Sapporo, Toyama, Nagoya, Tottori, Fukuoka, and Cape Hedo (Okinawa) in Japan during October 2008-December 2010 using automatic wet and dry separating samplers. Mineral dust weights in water-insoluble residue were estimated from Fe contents measured using an X-ray fluorescence analyser. Wet and dry deposition fluxes of mineral dusts were both high in spring and low in summer, showing similar seasonal variations to frequency of aeolian dust events (Kosa) in Japan. For wet deposition, highest and lowest annual dust fluxes were found at Toyama (9.6 g m-2 yr-1) and at Cape Hedo (1.7 g m-2 yr-1) as average values in 2009 and 2010. Higher wet deposition fluxes were observed at Toyama and Tottori, where frequent precipitation (> 60% days per month) was observed during dusty seasons. For dry deposition among Toyama, Tottori, Fukuoka, and Cape Hedo, the highest and lowest annual dust fluxes were found respectively at Fukuoka (5.2 g m-2 yr-1) and at Cape Hedo (2.0 g m-2 yr-1) as average values in 2009 and 2010. The average ratio of wet and dry deposition fluxes was the highest at Toyama (3.3) and the lowest at Hedo (0.82), showing a larger contribution of the dry process at western sites, probably because of the distance from desert source regions and because of the effectiveness of the wet process in the dusty season. Size distributions of refractory dust particles were obtained using four-stage filtration: > 20, > 10, > 5, and > 1 μm diameter. Weight fractions

  1. Gas-phase saturation and evaporative cooling effects during wet compression of a fuel aerosol under RCM conditions

    SciTech Connect

    Goldsborough, S.S.; Johnson, M.V.; Zhu, G.S.; Aggarwal, S.K.

    2011-01-15

    Wet compression of a fuel aerosol has been proposed as a means of creating gas-phase mixtures of involatile diesel-representative fuels and oxidizer + diluent gases for rapid compression machine (RCM) experiments. The use of high concentration aerosols (e.g., {proportional_to}0.1 mL{sub fuel}/L{sub gas}, {proportional_to}1 x 10{sup 9} droplets/L{sub gas} for stoichiometric fuel loading at ambient conditions) can result in droplet-droplet interactions which lead to significant gas-phase fuel saturation and evaporative cooling during the volumetric compression process. In addition, localized stratification (i.e., on the droplet scale) of the fuel vapor and of temperature can lead to non-homogeneous reaction and heat release processes - features which could prevent adequate segregation of the underlying chemical kinetic rates from rates of physical transport. These characteristics are dependent on many factors including physical parameters such as overall fuel loading and initial droplet size relative to the compression rate, as well as fuel and diluent properties such as the boiling curve, vaporization enthalpy, heat capacity, and mass and thermal diffusivities. This study investigates the physical issues, especially fuel saturation and evaporative cooling effects, using a spherically-symmetric, single-droplet wet compression model. n-Dodecane is used as the fuel with the gas containing 21% O{sub 2} and 79% N{sub 2}. An overall compression time and compression ratio of 15.3 ms and 13.4 are used, respectively. It is found that smaller droplets (d{sub 0}{proportional_to} 2-3 {mu}m) are more affected by 'far-field' saturation and cooling effects, while larger droplets (d{sub 0}{proportional_to} 14 {mu}m) result in greater localized stratification of the gas-phase due to the larger diffusion distances for heat and mass transport. Vaporization of larger droplets is more affected by the volumetric compression process since evaporation requires more time to be completed

  2. Relationships between the El Niño-Southern Oscillation, precipitation, and nitrogen wet deposition rates in the contiguous United States

    NASA Astrophysics Data System (ADS)

    Nergui, Tsengel; Evans, R. David; Adam, Jennifer C.; Chung, Serena H.

    2016-11-01

    Human activities have significantly increased reactive nitrogen (N) in the environment, leading to adverse effects on various ecosystems. We used 1979-2012 seasonal inorganic N wet deposition data from the National Atmospheric Deposition Program to evaluate the relationship between the El Niño-Southern Oscillation (ENSO) and N wet deposition in the contiguous U.S. The correlations between precipitation and inorganic N wet deposition were the strongest and most spatially extensive during winter; up to 62% and 53% of the 2 to 6 year variations of precipitation and N wet deposition rates, respectively, in the Rocky Mountains, along the coast of the Gulf of Mexico and near the Great Lakes, can be explained by variation in the NINO3.4 climate index, which was used as a measure of ENSO activity. During El Niño winters, precipitation and N wet deposition rates were higher than normal in the southern U.S., while La Niña events brought higher precipitation and N wet deposition to the Rocky Mountains and Great Lakes regions. Wintertime N wet deposition correlations held through springtime in the Great Lakes and the northeast; however, correlations between NINO3.4 and precipitation were not significant at most sites, suggesting factors besides precipitation amount contributed to the 2 to 6 year variation of N wet deposition in these regions. As the frequency, strength, and types of ENSO change in the future, interannual variability of N wet deposition will be affected, indirectly affecting spatial distribution of dry N deposition and potentially changing the overall spatial patterns of N deposition.

  3. The effect of scatter and attenuation on aerosol deposition as determined by gamma scintigraphy.

    PubMed

    Lee, Z; Berridge, M S; Nelson, A D; Heald, D L

    2001-01-01

    Gamma scintigraphy is often used to quantify deposition patterns from aerosol inhalers. The errors caused by scatter and tissue attenuation in planar Tc-99m gamma scintigraphy were investigated based on the data collected from four subjects in this study. Several error correction methods were tested. The results from two scatter correction methods, Jaszczak's method and factor analysis of dynamic sequences (FADS), were similar. Scatter accounted for 20% of raw data in the whole lung, 20% in the oropharynx, and 43% in the central airways and esophagus. Three attenuation correction methods were investigated and compared. These were: uniform attenuation correction (UAC), a known method used for inhalation drug imaging work; the broad-beam attenuation correction used for organ imaging in nuclear medicine; and a narrow-beam inhomogeneous tissue attenuation correction proposed in this study. The three methods differed significantly (p < 0.05), but all indicated that attenuation is a severe quantification problem. The narrow beam attenuation correction with scatter correction, showed that raw data underestimated tracer deposition by 44% in the lung, 137% in the oropharynx, and 153% in the trachea/esophageal region. To quantify aerosol lung deposition using planar scintigraphy even in relative terms, corrections are necessary. Much of the literature concerning quantified aerosol dose distributions measured by gamma scintigraphy needs to be interpreted carefully.

  4. Aerosol deposition in the human lung following administration from a microprocessor controlled pressurised metered dose inhaler.

    PubMed Central

    Farr, S. J.; Rowe, A. M.; Rubsamen, R.; Taylor, G.

    1995-01-01

    BACKGROUND--Gamma scintigraphy was employed to assess the deposition of aerosols emitted from a pressurised metered dose inhaler (MDI) contained in a microprocessor controlled device (SmartMist), a system which analyses an inspiratory flow profile and automatically actuates the MDI when predefined conditions of flow rate and cumulative inspired volume coincide. METHODS--Micronised salbutamol particles contained in a commercial MDI (Ventolin) were labelled with 99m-technetium using a method validated by the determination of (1) aerosol size characteristics of the drug and radiotracer following actuation into an eight stage cascade impactor and (2) shot potencies of these non-volatile components as a function of actuation number. Using nine healthy volunteers in a randomised factorial interaction design the effect of inspiratory flow rate (slow, 30 l/min; medium, 90 l/min; fast, 270 l/min) combined with cumulative inspired volume (early, 300 ml; late, 3000 ml) was determined on total and regional aerosol lung deposition using the technique of gamma scintigraphy. RESULTS--The SmartMist firing at the medium/early setting (medium flow and early in the cumulative inspired volume) resulted in the highest lung deposition at 18.6 (1.42)%. The slow/early setting gave the second highest deposition at 14.1 (2.06)% with the fast/late setting resulting in the lowest (7.6 (1.15)%). Peripheral lung deposition obtained for the medium/early (9.1 (0.9)%) and slow/early (7.5 (1.06)%) settings were equivalent but higher than those obtained with the other treatments. This reflected the lower total lung deposition at these other settings as no difference in regional deposition, expressed as a volume corrected central zone:peripheral zone ratio, was apparent for all modes of inhalation studied. CONCLUSIONS--The SmartMist device allowed reproducible actuation of an MDI at a preprogrammed point during inspiration. The extent of aerosol deposition in the lung is affected by a change in

  5. Development of a wet-chemical method for the speciation of iron in atmospheric aerosols.

    PubMed

    Majestic, Brian J; Schauer, James J; Shafer, Martin M; Turner, Jay R; Fine, Philip M; Singh, Manisha; Sioutas, Constantinos

    2006-04-01

    The ability to quantify the chemical and physical forms of transition metals in atmospheric particulate matter (PM) is essential in determining potential human health and ecological effects. A method for the speciation of iron in atmospheric PM has been adapted which involves extraction in a well-defined solution followed by oxidation state specific detection. The method was applied to a suite of environmental aerosols. Ambient atmospheric aerosols in an urban area of St. Louis (the St. Louis-Midwest Supersite) were collected on Teflon substrates and were leached in one of four different solutions: (1) >18.0 Momega water; (2) 140 microM NaCl solution; (3) pH = 7.4 NaHCO3 solution; and (4) pH = 4.3 acetate buffering system. Fe(ll) was determined directly using the Ferrozine method as adapted to liquid waveguide spectrophotometry using a 1 m path-length cell. Fe(lll) was determined similarly after reduction to Fe(ll). It was found that, at low ionic strength, pH exerted a major influence on Fe(ll) solubility with the greatest Fe(ll) concentration consistently found in the pH = 4.3 acetate buffer. Soluble Fe(lll) (as defined by a 0.2 microm filter) varied little with extractant, which implies that most of the Fe(lll) detected was colloidal. To characterize well-defined materials for future reference, NIST standard reference materials were also analyzed for soluble Fe(ll) and Fe(lll). For all SRMs tested, a maximum of 2.4% of the total iron (Urban Dust 1649a) was soluble in pH = 4.3 acetate buffer. For calibration curves covering the ranges of 0.5-20 microg/L Fe(ll), excellent linearity was observed in all leaching solutions with R2 values of > 0.999. Co-located filters were used to test the effect of storage time on iron oxidation state in the ambient particles as a function of time. On two samples, an average Fe(ll) decay rate of 0.89 and 0.57 ng Fe(ll) g(-1) PM day(-1) was determined from the slope of the regression, however this decrease was determined not to be

  6. Dense nanocrystalline yttrium iron garnet films formed at room temperature by aerosol deposition

    SciTech Connect

    Johnson, Scooter D. Glaser, Evan R.; Cheng, Shu-Fan; Hite, Jennifer

    2016-04-15

    Highlights: • We deposit yttrium iron garnet films at room temperature using aerosol deposition. • Films are 96% of theoretical density for yttrium iron garnet. • We report magnetic and structural properties post-deposition and post-annealing. • Low-temperature annealing decreases the FMR linewidth. • We discuss features of the FMR spectra at each anneal temperature. - Abstract: We have employed aerosol deposition to form polycrystalline yttrium iron garnet (YIG) films on sapphire at room temperature that are 90–96% dense. We characterize the structural and dynamic magnetic properties of the dense films using scanning electron microscopy, X-ray diffraction, and ferromagnetic resonance techniques. We find that the as-deposited films are pure single-phase YIG formed of compact polycrystallites ∼20 nm in size. The ferromagnetic resonance mode occurs at 2829 G with a linewidth of 308 G. We perform a series of successive anneals up to 1000 °C on a film to explore heat treatment on the ferromagnetic resonance linewidth. We find the narrowest linewidth of 98 G occurs after a 750 °C anneal.

  7. Formation of Thick Dense Yttrium Iron Garnet Films Using Aerosol Deposition.

    PubMed

    Johnson, Scooter D; Glaser, Evan R; Kub, Fritz J; Eddy, Charles R

    2015-05-15

    Aerosol deposition (AD) is a thick-film deposition process that can produce layers up to several hundred micrometers thick with densities greater than 95% of the bulk. The primary advantage of AD is that the deposition takes place entirely at ambient temperature; thereby enabling film growth in material systems with disparate melting temperatures. This report describes in detail the processing steps for preparing the powder and for performing AD using the custom-built system. Representative characterization results are presented from scanning electron microscopy, profilometry, and ferromagnetic resonance for films grown in this system. As a representative overview of the capabilities of the system, focus is given to a sample produced following the described protocol and system setup. Results indicate that this system can successfully deposit 11 µm thick yttrium iron garnet films that are  > 90% of the bulk density during a single 5 min deposition run. A discussion of methods to afford better control of the aerosol and particle selection for improved thickness and roughness variations in the film is provided.

  8. Identification sources of pollen spectra in dry and wet atmospheric deposition in the forest-steppe zone of Altai Krai (Russia)

    NASA Astrophysics Data System (ADS)

    Ryabchinskaya, Natalia; Nenasheva, Galina; Malygina, Natalia

    2015-04-01

    Pollen spectra circulating in the atmosphere contain the important information about primary biological aerosol particles (PBAP), worldwide interest in which has significantly increased in recent decades [Despres, 2012]. It is related to the fact that many researchers suggest primary aerosols as a condensation nucleus significantly affected on the formation of clouds and precipitation and, consequently, on the hydrological cycle and climate, especially at the regional level [Andreae et al., 2008; Poschlet et al., 2010; Prenni et al., 2009]. We present the comparison of pollen spectra obtained during the dry and wet atmospheric deposition in Altai Krai (Russia) and identification of the sources/regions of their receipts. Altai Krai is located in the center of the Eurasian continent, at the border of several natural and climatic zones. A significant part of the region's territory is characterized as a forest-steppe zone with a lot of natural and anthropogenic landscapes, accompanied by continental climate. It provides a rich diversity of natural vegetation and cultural associations. During last 10 years pollen grains has been monitored in the airspace of Barnaul city (the capital of Altai Krai) located in the central part of the forest-steppe zone). During the monitoring, the attempts to determine the origin of pollen spectra (local or introduced) were made as well. In the long-term average dates of the first wave of dusting in the spring season 2014 Burkard pollen traps were used in order to monitor the airspace in Barnaul, namely dry deposition of pollen grains [Nenasheva, 2013]. To estimate the wet deposition PBAP (pollen), which can reach 80% in the middle latitudes, precipitation sampler were installed close to Burkard pollen traps in order to sample precipitation. The samples were filtered through a filter having a pore diameter of 1 µm, then prepared and examined for the presence of pollen grains. The comparison of the results of pollen analysis of 10 samples

  9. Detection of cw-related species in complex aerosol particles deposited on surfaces with an ion trap-based aerosol mass spectrometer

    SciTech Connect

    Harris, William A; Reilly, Pete; Whitten, William B

    2007-01-01

    A new type of aerosol mass spectrometer was developed by minimal modification of an existing commercial ion trap to analyze the semivolatile components of aerosols in real time. An aerodynamic lens-based inlet system created a well-collimated particle beam that impacted into the heated ionization volume of the commercial ion trap mass spectrometer. The semivolatile components of the aerosols were thermally vaporized and ionized by electron impact or chemical ionization in the source. The nascent ions were extracted and injected into the ion trap for mass analysis. The utility of this instrument was demonstrated by identifying semivolatile analytes in complex aerosols. This study is part of an ongoing effort to develop methods for identifying chemical species related to CW agent exposure. Our efforts focused on detection of CW-related species doped on omnipresent aerosols such as house dust particles vacuumed from various surfaces found in any office building. The doped aerosols were sampled directly into the inlet of our mass spectrometer from the vacuumed particle stream. The semivolatile analytes were deposited on house dust and identified by positive ion chemical ionization mass spectrometry up to 2.5 h after deposition. Our results suggest that the observed semivolatile species may have been chemisorbed on some of the particle surfaces in submonolayer concentrations and may remain hours after deposition. This research suggests that identification of trace CW agent-related species should be feasible by this technique.

  10. Wet deposition of fission-product isotopes to North America from the Fukushima Dai-ichi incident, March 2011

    USGS Publications Warehouse

    Wetherbee, Gregory A.; Gay, David A.; Debey, Timothy M.; Lehmann, Christopher M.B.; Nilles, Mark A.

    2012-01-01

    Using the infrastructure of the National Atmospheric Deposition Program (NADP), numerous measurements of radionuclide wet deposition over North America were made for 167 NADP sites before and after the Fukushima Dai-ichi Nuclear Power Station incident of March 12, 2011. For the period from March 8 through April 5, 2011, wet-only precipitation samples were collected by NADP and analyzed for fission-product isotopes within whole-water and filterable solid samples by the United States Geological Survey using gamma spectrometry. Variable amounts of 131I, 134Cs, or 137Cs were measured at approximately 21% of sampled NADP sites distributed widely across the contiguous United States and Alaska. Calculated 1- to 2-week individual radionuclide deposition fluxes ranged from 0.47 to 5100 Becquerels per square meter during the sampling period. Wet deposition activity was small compared to measured activity already present in U.S. soil. NADP networks responded to this complex disaster, and provided scientifically valid measurements that are comparable and complementary to other networks in North America and Europe.

  11. Development of aerosol assisted chemical vapor deposition for thin film fabrication

    NASA Astrophysics Data System (ADS)

    Maulana, Dwindra Wilham; Marthatika, Dian; Panatarani, Camellia; Mindara, Jajat Yuda; Joni, I. Made

    2016-02-01

    Chemical vapor deposition (CVD) is widely used to grow a thin film applied in many industrial applications. This paper report the development of an aerosol assisted chemical vapor deposition (AACVD) which is one of the CVD methods. Newly developed AACVD system consists of a chamber of pyrex glass, two wire-heating elements placed to cover pyrex glass, a substrate holder, and an aerosol generator using an air brush sprayer. The temperature control system was developed to prevent condensation on the chamber walls. The control performances such as the overshoot and settling time were obtained from of the developed temperature controller. Wire-heating elements were controlled at certain setting value to heat the injected aerosol to form a thin film in the substrate. The performance of as-developed AACVD system tested to form a thin film where aerosol was sprayed into the chamber with a flow rate of 7 liters/minutes, and vary in temperatures and concentrations of precursor. The temperature control system have an overshoot around 25 °C from the desired set point temperature, very small temperature ripple 2 °C and a settling time of 20 minutes. As-developed AACVD successfully fabricated a ZnO thin film with thickness of below 1 µm. The performances of system on formation of thin films influenced by the generally controlled process such as values of setting temperature and concentration where the aerosol flow rate was fixed. Higher temperature was applied, the more uniform ZnO thin films were produced. In addition, temperature of the substrate also affected on surface roughness of the obtained films, while concentration of ZnO precursor determined the thickness of produce films. It is concluded that newly simple AACVD can be applied to produce a thin film.

  12. Aerosols

    Atmospheric Science Data Center

    2013-04-17

    ... article title:  Aerosols over Central and Eastern Europe     View Larger Image ... last weeks of March 2003, widespread aerosol pollution over Europe was detected by several satellite-borne instruments. The Multi-angle ...

  13. Latitudinal distributions of activities in atmospheric aerosols, deposition fluxes, and soil inventories of ⁷Be in the East Asian monsoon zone.

    PubMed

    Gai, N; Pan, J; Yin, X C; Zhu, X H; Yu, H Q; Li, Y; Tan, K Y; Jiao, X C; Yang, Y L

    2015-10-01

    Activities of atmospheric aerosols, bulk deposition fluxes, and undisturbed soil inventories of (7)Be were investigated in China's East Asian monsoon zone at various latitudes ranging from 23.8°N to 43.5°N. The annual latitudinal distributions of (7)Be concentrations in aerosols follow a distribution pattern which looks similar to a normal distribution with the maxima occurring in the mid-latitude region. Simultaneous measurements of (7)Be at various latitudes suggest that atmospheric circulation may play an important role in the latitudinal distributions of (7)Be in surface air. Latitude and wet precipitation are the main factors controlling the bulk (7)Be depositional fluxes. Significant seasonal variations in (7)Be depositional fluxes in Beijing, a mid-latitude city, were observed with the highest flux in summer and the lowest in winter, whereas less seasonality were found in the high- and the low-latitude cities. The highest (7)Be inventory in undisturbed soils in summer also occurred at a mid-latitudinal area in the East Asian monsoon zone. Precipitation is the main factor controlling the (7)Be soil inventory in Qingdao with the highest values occurring in autumn followed by summer.

  14. Enhanced Deposition by Electrostatic Field-Assistance Aggravating Diesel Exhaust Aerosol Toxicity for Human Lung Cells.

    PubMed

    Stoehr, Linda C; Madl, Pierre; Boyles, Matthew S P; Zauner, Roland; Wimmer, Monika; Wiegand, Harald; Andosch, Ancuela; Kasper, Gerhard; Pesch, Markus; Lütz-Meindl, Ursula; Himly, Martin; Duschl, Albert

    2015-07-21

    Air pollution is associated with increased risk of cardiovascular and pulmonary diseases, but conventional air quality monitoring gives no information about biological consequences. Exposing human lung cells at the air-liquid interface (ALI) to ambient aerosol could help identify acute biological responses. This study investigated electrode-assisted deposition of diesel exhaust aerosol (DEA) on human lung epithelial cells (A549) in a prototype exposure chamber. A549 cells were exposed to DEA at the ALI and under submerged conditions in different electrostatic fields (EFs) and were assessed for cell viability, membrane integrity, and IL-8 secretion. Qualitative differences of the DEA and its deposition under different EFs were characterized using scanning mobility particle sizer (SMPS) measurements, transmission electron microscopy (TEM), and electron energy loss spectroscopy (EELS). Upon exposure to DEA only, cell viability decreased and membrane impairment increased for cells at the ALI; submerged cells were unaffected. These responses were enhanced upon application of an EF, as was DEA deposition. No adverse effects were observed for filtered DEA or air only, confirming particle-induced responses. The prototype exposure chamber proved suitable for testing DEA-induced biological responses of cells at the ALI using electrode-assisted deposition and may be useful for analysis of other air pollutants.

  15. Aerosol-Assisted Chemical Vapor Deposited Thin Films for Space Photovoltaics

    NASA Technical Reports Server (NTRS)

    Hepp, Aloysius F.; McNatt, Jeremiah; Dickman, John E.; Jin, Michael H.-C.; Banger, Kulbinder K.; Kelly, Christopher V.; AquinoGonzalez, Angel R.; Rockett, Angus A.

    2006-01-01

    Copper indium disulfide thin films were deposited via aerosol-assisted chemical vapor deposition using single source precursors. Processing and post-processing parameters were varied in order to modify morphology, stoichiometry, crystallography, electrical properties, and optical properties in order to optimize device-quality material. Growth at atmospheric pressure in a horizontal hot-wall reactor at 395 C yielded best device films. Placing the susceptor closer to the evaporation zone and flowing a more precursor-rich carrier gas through the reactor yielded shinier, smoother, denser-looking films. Growth of (112)-oriented films yielded more Cu-rich films with fewer secondary phases than growth of (204)/(220)-oriented films. Post-deposition sulfur-vapor annealing enhanced stoichiometry and crystallinity of the films. Photoluminescence studies revealed four major emission bands (1.45, 1.43, 1.37, and 1.32 eV) and a broad band associated with deep defects. The highest device efficiency for an aerosol-assisted chemical vapor deposited cell was 1.03 percent.

  16. Dry Lung as a Physical Model in Studies of Aerosol Deposition.

    PubMed

    Morozov, Victor N; Kanev, Igor L

    2015-10-01

    A new physical model was developed to evaluate the deposition of micro- and nanoaerosol particles (NAPs) into the lungs as a function of size and charges. The model was manufactured of a dry, inflated swine lung produced by Nasco company (Fort Atkinson, WI). The dry lung was cut into two lobes and a conductive tube was glued into the bronchial tube. The upper 1-2-mm-thick layer of the lung lobe was removed with a razor blade to expose the alveoli. The lobe was further enclosed into a plastic bag and placed within a metalized plastic box. The probability of aerosol deposition was calculated by comparing the size distribution of NAPs passed through the lung with that of control, where aerosol passed through a box bypassing the lung. Using this new lung model, it was demonstrated that charged NAPs are deposited inside the lung substantially more efficiently than neutral ones. It was also demonstrated that deposition of neutral NAPs well fits prediction of the Multiple-Path Particle Dosimetry (MPPD) model developed by the Applied Research Associates, Inc. (ARA).

  17. Control on wetting properties of spin-deposited silica films by surface silylation method

    NASA Astrophysics Data System (ADS)

    Rao, A. Venkateswara; Latthe, Sanjay S.; Dhere, Sunetra L.; Pawar, Swapnali S.; Imai, Hiroaki; Ganesan, V.; Gupta, Satish C.; Wagh, Pratap B.

    2010-01-01

    Control on the wettability of solid materials by liquid is a classical and key issue in surface engineering. Optically transparent water-repellent silica films have been spin-deposited on glass substrates at room temperature (˜27 °C). The wetting behavior of silica films was controlled by surface silylation method using dimethylchlorosilane (DMCS) as a silylating reagent. A coating sol was prepared by keeping the molar ratio of methyltrimethoxysilane (MTMS) precursor, methanol (MeOH) solvent, water (H 2O) constant at 1:8.8:2.64 respectively, with 4 M NH 4OH as a catalyst throughout the experiments and the amount of DMCS in hexane was varied from 0 to 12 vol.%. It was found that with an increase in vol.% of DMCS, the water contact angle values of the films increased from 78° to 136°. At 12 vol.% of DMCS, the film shows static water contact angle as high as 136° and water sliding angle as low as 18°. The hydrophobic silica films retained their water repellency up to a temperature 295 °C and above this temperature the films show superhydrophilic behavior. These results are compared with our earlier research work done on silylation of silica surface using hexamethyldisilazane (HMDZ) and trimethylchlorosilane (TMCS). The hydrophobic silica films were characterized by taking into consideration the Fourier transform infrared (FT-IR) spectroscopy, thermo gravimetric-differential thermal (TG-DT) analyses, scanning electron microscopy (SEM), atomic force microscopy (AFM), % of optical transmission, thermal and chemical aging tests, humidity tests, static and dynamic water contact angle measurements.

  18. Monthly variations in nitrogen isotopes of ammonium and nitrate in wet deposition at Guangzhou, south China

    NASA Astrophysics Data System (ADS)

    Jia, Guodong; Chen, Fajin

    2010-06-01

    Monthly nitrogen isotopes of ammonium and nitrate in wet deposition in the city of Guangzhou, and the causes of their variability, are reported in this paper. Nitrate δ 15N showed nearly constant values around zero in the dry season (October to April), but oscillating values from negative to positive in the rainy season (May to September). By contrast, ammonium δ 15N displayed lower values during the rainy season than in the dry season. The rural area north of the city was considered as the prominent source of ammonium and nitrate in spring and early summer (May and June), as suggested by their concurrent negative isotopic trends and higher NH 4+/NO 3- ratios. From July to September, different dominating sources from the city, i.e., fossil fuel combustion for nitrate, and sewage and waste emission for ammonium, caused disparate δ 15N trends of the two species, showing positive nitrate δ 15N, but still negative ammonium δ 15N. During the cool dry season, the high values of ammonium δ 15N and concurrently low NH 4+/NO 3- ratios suggested the decrease in NH 3 volatilization and relatively important thermogenic origin of ammonium, but the intermediate nitrate δ 15N values around zero may be a result of a balanced emission of NO x from the city and the rural areas. The isotopic effects of chemical conversion of NO x to nitrate and washout of nitrate were ruled out as significant causes of nitrate δ 15N variability, but ammonium washout, during which 15N is assumed to be preferentially removed, may partly contribute to the ammonium δ 15N variability.

  19. Sources of nitrogen and sulfur in wet deposition at Guiyang, southwest China

    NASA Astrophysics Data System (ADS)

    Xiao, H.-Y.; Liu, C.-Q.

    Whilst limited information on nitrogen and sulfur isotopic composition in wet deposition in cities is available, very few data on the sources of sulfur and nitrogen in both light rainfalls (<5 mm in precipitation and <4 h in duration) and heavy rainfalls (>100 mm in precipitation and <24 h in duration, caused by typhoon from the Pacific Ocean) have been accumulated. For both species a significant difference in mean sulfur and nitrogen isotopic composition was reported in this study between samples collected from light rainfalls (-4.9±2.8‰ for sulfate and +2.0±4.4‰ for nitrate) and heavy rainfalls (+4.6±5.0‰ for sulfate and +4.1±4.0‰ for nitrate), supporting that sulfur and nitrogen in the two types of rainfalls are of different sources. For sulfate, the negative δ34S values in light rainfalls are associated with local sources (coal combustion and biogenic sulfur) while sulfur in heavy rainfalls, with positive δ34S values, is of maritime origin. For nitrate, there is no definite information on the sources of nitrogen in light rainfalls because of a wide range of δ15N values (-3.8‰ to +10.7‰), but the higher δ15N values (>+6.0‰) are probably ascribed to dry deposition or coal-fired power plants; the mean δ15N value of +4.1‰ in heavy rainfalls may also be a reflection of maritime origin. Measurements of δ15N values for ammonium in light rainfalls show that δ15N values are closely related with ammonium concentrations ( R2=0.92). The lower values in the range of δ15N values (-1.7‰ to -22.0‰) for ammonium are due to less incorporation of 15N by cloud water, which probably has a δ15N value of about -22.0‰. But the higher concentrations (averaging 1.25 mg l -1) and lower δ15N values (averaging -12.2±6.7‰) indicated that ammonium steps from excretory wastes are extensively applied in agriculture and NH 3 released from soils.

  20. The El Niño Southern Oscillation (ENSO) induced modulations in precipitation and nitrogen wet deposition rates in the continental United States

    NASA Astrophysics Data System (ADS)

    Nergui, T.; Chung, S. H.; Adam, J. C.; Evans, R. D.

    2015-12-01

    The ENSO affects atmospheric nitrogen (N) deposition rates through its modulation on N wet deposition. Precipitation and wet deposition measurements at 151 sites of the National Atmospheric Deposition Program/National Trends Network and the NINO3.4 SST climate index from the NOAA's Climate Prediction Center are analyzed to determine the impacts of the ENSO on N wet deposition and precipitation rates in the continental U.S. Precipitation and N wet deposition time series are dominated by high frequency components; however, they contain a wide range of inter-annual frequency components depending on the location. At the 2-to 6-year timescale, variability of precipitation and N wet deposition rates in the Pacific Northwest, the Rocky Mountains, the Gulf States, the Northeast, and the Great Lakes regions are correlated with that of the NINO3.4 index (r2= 0.09-0.59 for precipitation and r2= 0.09-0.52 for N wet deposition, p<0.05). The spatial patterns and strength of the correlations vary by region and season. The correlations are the strongest and most spatially extensive during winter; 46-62% and 46-53% of the 2- to 6-year variability of precipitation and N wet deposition rates in the Rocky Mountains, the Gulf of Mexico, and near the Great Lakes can be explained by ENSO activity. The wintertime relationships tend to hold through springtime in the Great Lakes, the Ohio River Valley, and the Northeast. During the El Niño winters and springs, N wet deposition rates are higher than normal (greater than the 70thpercentile) in the southern Great Plains and the Gulf Coast. Winter and spring La Niña episodes bring precipitation and N wet deposition rates above normal over the Cascades, the Ohio River Valley, the Northeast and the Great Lakes regions. The ensemble mean of eleven coupled General Circulation Models (Yeh et al., 2009) shows that the weak ENSO cycles, having small to moderate amplitudes and reoccurring in shorter time intervals, are projected to dominate in the 21

  1. Quality of wet deposition in the Grand Calumet River watershed, northwestern Indiana, June 30, 1992-August 31, 1993

    USGS Publications Warehouse

    Willoughby, T.C.

    1995-01-01

    Northwestern Indiana is one of the most heavily industrialized and largest steel-producing areas in the United States. High temperature processes, such as fossil-fuel combustion and steel production, release contaminants to the atmosphere that may result in wet deposition being a major contributor to major ion and trace-metal loadings in north- western Indiana and Lake Michigan. A wet-deposition collection site was established at the Gary (Indiana) Regional Airport in June 1992 to monitor the chemical quality of wet deposition. Weekly samples were collected at this site from June 30, 1992, through August 31, 1993, and were analyzed for pH, specific conductance, and selected major ions and trace metals. Forty-eight samples collected during the study were of sufficient volumes for some of the determinations to be performed. Median constituent concentrations were determined for samples collected during warm weather and cold weather (November 1 through March 31). Median concentrations were substituted for missing values from samples with insufficient volumes for analysis of all the constituents of interest. Constituent concentrations were converted to weekly loadings. Two values were calculated to provide a range for the weekly loading for samples with measured concentrations of constituents less than the method reporting limit. The minimum weekly loading was computed by substituting zero for the constituent concentration; the maximum weekly loading was computed by substituting the method reporting limit for the concentration. If all of the sample concentrations measured were greater than the method reporting limit, an annual loading value was computed. The annual loadings could be used to assist in estimating the contribution of wet deposition to the total annual constituent loadings in the Grand Calumet River in northwestern Indiana.

  2. CuInS2 Films Deposited by Aerosol-Assisted Chemical Vapor Deposition Using Ternary Single-Source Precursors

    NASA Technical Reports Server (NTRS)

    Jin, Michael; Banger, Kal; Harris, Jerry; Hepp, Aloysius

    2003-01-01

    Polycrystalline CuInS2 films were deposited by aerosol-assisted chemical vapor deposition using both solid and liquid ternary single-source precursors (SSPs) which were prepared in-house. Films with either (112) or (204/220) preferred orientation, had a chalcopyrite structure, and (112)-oriented films contained more copper than (204/220)-oriented films. The preferred orientation of the film is likely related to the decomposition and reaction kinetics associated with the molecular structure of the precursors at the substrate. Interestingly, the (204/220)-oriented films were always In-rich and were accompanied by a secondary phase. From the results of post-growth annealing, etching experiments, and Raman spectroscopic data, the secondary phase was identified as an In-rich compound. On the contrary, (112)-oriented films were always obtained with a minimal amount of the secondary phase, and had a maximum grain size of about 0.5 micron. Electrical and optical properties of all the films grown were characterized. They all showed p-type conduction with an electrical resistivity between 0.1 and 30 Omega-cm, and an optical band gap of approximately 1.46 eV +/- 0.02, as deposited. The material properties of deposited films revealed this methodology of using SSPs for fabricating chalcopyrite-based solar cells to be highly promising.

  3. CuInS2 Films Deposited by Aerosol-Assisted Chemical Vapor Deposition Using Ternary Single-Source Precursors

    NASA Technical Reports Server (NTRS)

    Jin, Michael H.-C.; Banger, Kulbinder K.; Harris, Jerry D.; Hepp, Aloysius F.

    2004-01-01

    Polycrystalline CuInS2 films were deposited by aerosol-assisted chemical vapor deposition using both solid and liquid ternary single-source precursors (SSPs) prepared in-house. Films with either (112) or (204/220) preferred orientation were obtained, and compositional analysis showed that (112)-oriented films contained more copper than (204/220)-oriented films. Using X-ray diffraction, the signature of chalcopyrite structure was often confirmed for (112)-oriented films. The preferred orientation of the film is likely related to the decomposition and reaction kinetics associated with the molecular structure of the precursors at the substrate. Interestingly, the (204/220)-oriented films were always accompanied by a secondary phase, which was identified as an unknown In-rich compound from the results of post-growth annealing, etching experiments, and Raman spectroscopic data. By increasing Cu to In ratio in the film, (112)-oriented films were obtained with a maximum grain size of about 0.5 micrometers, and their X-ray diffractions did not show any observable signature of the In secondary phase. Electrical and optical properties of all the films grown were characterized. They all showed p-type conduction with an electrical resistivity between 0.1 omega cm and 30 omega cm, and an optical band gap of 1.46eV +/- 0.02, as deposited. The material properties of deposited films revealed this methodology of using SSPs for fabricating chalcopyrite-based solar cells to be highly promising.

  4. The stability of hydrogen ion and specific conductance in filtered wet-deposition samples stored at ambient temperatures

    USGS Publications Warehouse

    Gordon, J.D.; Schroder, L.J.; Morden-Moore, A. L.; Bowersox, V.C.

    1995-01-01

    Separate experiments by the U.S. Geological Survey (USGS) and the Illinois State Water Survey Central Analytical Laboratory (CAL) independently assessed the stability of hydrogen ion and specific conductance in filtered wet-deposition samples stored at ambient temperatures. The USGS experiment represented a test of sample stability under a diverse range of conditions, whereas the CAL experiment was a controlled test of sample stability. In the experiment by the USGS, a statistically significant (?? = 0.05) relation between [H+] and time was found for the composited filtered, natural, wet-deposition solution when all reported values are included in the analysis. However, if two outlying pH values most likely representing measurement error are excluded from the analysis, the change in [H+] over time was not statistically significant. In the experiment by the CAL, randomly selected samples were reanalyzed between July 1984 and February 1991. The original analysis and reanalysis pairs revealed that [H+] differences, although very small, were statistically different from zero, whereas specific-conductance differences were not. Nevertheless, the results of the CAL reanalysis project indicate there appears to be no consistent, chemically significant degradation in sample integrity with regard to [H+] and specific conductance while samples are stored at room temperature at the CAL. Based on the results of the CAL and USGS studies, short-term (45-60 day) stability of [H+] and specific conductance in natural filtered wet-deposition samples that are shipped and stored unchilled at ambient temperatures was satisfactory.

  5. Mobilization and distribution of lead originating from roof dust and wet deposition in a roof runoff system.

    PubMed

    Yu, Jianghua; Yu, Haixia; Huang, Xiaogu

    2015-12-01

    In this research, the mobilization and distribution of lead originating in roof dust and wet deposition were investigated within a roof dust-rooftop-runoff system. The results indicated that lead from roof dust and wet deposition showed different transport dynamics in runoff system and that this process was significantly influenced by the rainfall intensity. Lead present in the roof dust could be easily washed off into the runoff, and nearly 60 % of the total lead content was present in particulate form. Most of the lead from the roof dust was transported during the late period of rainfall; however, the lead concentration was higher for several minutes at the rainfall beginning. Even though some of the lead from wet deposition, simulated with a standard isotope substance, was adsorbed onto adhered roof dust and/or retained on rooftop in runoff system, most of it (50-82 %) remained as dissolved lead in the runoff for rainfall events of varying intensity. Regarding the distribution of lead in the runoff system, the results indicated that it could be carried in the runoff in dissolved and particulate form, be adsorbed to adhered roof dust, or remain on the rooftop because of adsorption to the roof material. Lead from the different sources showed different distribution patterns that were also related to the rainfall intensity. Higher rainfall intensity resulted in a higher proportion of lead in the runoff and a lower proportion of lead remaining on the rooftop.

  6. Limited influence of dry deposition of semivolatile organic vapors on secondary organic aerosol formation in the urban plume

    NASA Astrophysics Data System (ADS)

    Hodzic, A.; Madronich, S.; Aumont, B.; Lee-Taylor, J.; Karl, T.; Camredon, M.; Mouchel-Vallon, C.

    2013-06-01

    The dry deposition of volatile organic compounds (VOCs) and its impact on secondary organic aerosols (SOA) are investigated in the Mexico City plume. Gas-phase chemistry and gas-particle partitioning of oxygenated VOCs are modeled with the Generator of Explicit Chemistry and Kinetics of Organics in the Atmosphere (GECKO-A) from C3 to C25 alkanes, alkenes, and light aromatics. Results show that dry deposition of oxidized gases is not an efficient sink for SOA, as it removes <5% of SOA within the city's boundary layer and ~15% downwind. Dry deposition competes with the gas-particle uptake, and only gases with fewer than ~12 carbons dry deposit while longer species partition to SOA. Because dry deposition of submicron aerosols is slow, condensation onto particles protects organic gases from deposition, thus increasing their atmospheric burden and lifetime. In the absence of this condensation, ~50% of the regionally produced mass would have been dry deposited.

  7. Impact of aerosol composition and foliage characteristics on forest canopy deposition rates: A laboratory study

    NASA Astrophysics Data System (ADS)

    Hornsby, K. E.; Pryor, S. C.

    2013-12-01

    Forests are a major sink for atmospheric aerosols. Hence it has been suggested that (i) increased tree planting in urban areas might lead to a reduction in aerosol particle concentrations and thus a reduction in respiratory conditions and heart complications, and (ii) forests may be responsible for removing a disproportionately large fraction of potentially climate-relevant fine and ultra-fine aerosol particles from the atmosphere. However, larger uncertainties remain with respect to controls on uptake rates for forests. E.g. the deposition flux partitioning between foliage and non-foliage elements, the influence of particle size and composition, the role of leaf surface morphology and stomatal aperture in surface uptake. Improved understanding of the relative importance of these factors and the variability across different tree species should help determine how much of a sink naturally occurring and planted forests can provide downstream of fine particle production. In this study, a sample of trees native to southern Indiana were exposed to ultra-fine aerosol particle populations in a 1.5 m x 1.5 m x 1.5 m Teflon chamber. Stable particle size distributions (PSD) with geometric mean diameters (GMD) ranging from 40 to 80 nm were generated from sodium chloride, ammonium nitrate, ammonium sulfate and sodium sulfite solutions using a TSI model 3940 Aerosol Generation System (AGS). The aerosol stream was diluted using scrubbed and dried zero air to allow a variation of total number concentration across two orders of magnitude. PSD in the chamber are continuously measured using a TSI Scanning Mobility Particle Spectrometer (SMPS) comprising an Electrostatic Classifier (EC model 3080) attached to a Long DMA (LDMA model 3081) and a TSI model 3025A Butanol Condensation Particle Counter (CPC) operated with both the internal diffusion loss and multiple charge corrections turned on. The composition of the chamber air was also monitored for carbon dioxide (CO2) and water vapor

  8. Size distribution of airborne particle-bound polybrominated diphenyl ethers and its implications for dry and wet deposition.

    PubMed

    Luo, Pei; Ni, Hong-Gang; Bao, Lian-Jun; Li, Shao-Meng; Zeng, Eddy Y

    2014-12-02

    Size distribution of particles in part dictates the environmental behavior of particle-bound organic pollutants in the atmosphere. The present study was conducted to examine the potential mechanisms responsible for the distribution of organic pollutants in size fractionated particles and their environmental implications, using an e-waste recycling zone in South China as a case study. Size-fractionated atmospheric particles were collected at the heights of 1.5, 5, and 20 m near two residential apartments and analyzed for polybrominated diphenyl ethers (PBDEs). The concentrations of particle-bound ΣPBDE (sum of 18 PBDE congeners) were significantly greater at 5 and 20 m than those at 1.5 m. The size-fractionated distributions of airborne ΣPBDE displayed trimodal peaks in 0.10–0.18, 1.8–3.2, and 10–18 μm at 1.5 m but only an unimodal peak in 1.0–1.8 μm at 20 m height. Emission sources, resuspension of dust and soil, and volatility of PBDEs were important factors influencing the size distribution of particle-bound PBDEs. The dry deposition fluxes of particle-bound PBDE estimated from the measured data in the present study were approximately twice the estimated wet deposition fluxes, with a total deposition flux of 3000 ng m(–2) d(–1). The relative contributions of particles to dry and wet deposition fluxes were also size-dependent, e.g., coarse (aerodynamic diameters (Dp) > 1.8 μm) and fine (Dp < 1.8 μm) particles dominated the dry and wet deposition fluxes of PBDEs, respectively.

  9. Lung Deposition Analyses of Inhaled Toxic Aerosols in Conventional and Less Harmful Cigarette Smoke: A Review

    PubMed Central

    Kleinstreuer, Clement; Feng, Yu

    2013-01-01

    Inhaled toxic aerosols of conventional cigarette smoke may impact not only the health of smokers, but also those exposed to second-stream smoke, especially children. Thus, less harmful cigarettes (LHCs), also called potential reduced exposure products (PREPs), or modified risk tobacco products (MRTP) have been designed by tobacco manufacturers to focus on the reduction of the concentration of carcinogenic components and toxicants in tobacco. However, some studies have pointed out that the new cigarette products may be actually more harmful than the conventional ones due to variations in puffing or post-puffing behavior, different physical and chemical characteristics of inhaled toxic aerosols, and longer exposure conditions. In order to understand the toxicological impact of tobacco smoke, it is essential for scientists, engineers and manufacturers to develop experiments, clinical investigations, and predictive numerical models for tracking the intake and deposition of toxicants of both LHCs and conventional cigarettes. Furthermore, to link inhaled toxicants to lung and other diseases, it is necessary to determine the physical mechanisms and parameters that have significant impacts on droplet/vapor transport and deposition. Complex mechanisms include droplet coagulation, hygroscopic growth, condensation and evaporation, vapor formation and changes in composition. Of interest are also different puffing behavior, smoke inlet conditions, subject geometries, and mass transfer of deposited material into systemic regions. This review article is intended to serve as an overview of contributions mainly published between 2009 and 2013, focusing on the potential health risks of toxicants in cigarette smoke, progress made in different approaches of impact analyses for inhaled toxic aerosols, as well as challenges and future directions. PMID:24065038

  10. Aerosol Deposition of Molybdenum: A Control on Nitrogen-Fixation and Tropical Forest Function

    NASA Astrophysics Data System (ADS)

    Wong, M.; Howarth, R. W.; Marino, R. M.; Mahowald, N. M.; Williams, E. R.

    2015-12-01

    Nitrogen fixation, the primary source of new nitrogen (N) to tropical forests, is exclusively catalyzed by the nitrogenase enzyme, which almost always requires molybdenum (Mo). Increasing evidence in recent years suggests that Mo availability may be low in highly weathered soils and can constrain N-fixation rates. Mo is generally either present in a highly soluble form (MoO42-) that is susceptible to leaching or tightly bound in minerals unavailable for biological uptake. To address how Mo is retained in highly weathered tropical systems to support N-fixation, atmospheric transport through dust and sea-salt aerosol spray were examined. Using a global atmospheric transport model computed from modeled meteorological fields, extrapolated dust and sea-salt aerosol Mo sources were used to calculate global distribution of Mo deposition. Dust deposition occurs across the entirety of some tropical forests, particularly the world's largest tropical forest in the Amazon Basin. The model indicates that the Amazon Basin receives substantial inputs of dust, especially the entire northern Amazon Basin, while the southern half receives less. Most of the dust reaching the Amazon originates from the Sahara Desert, and about half of this dust originates from one part of the Sahara, the Bodélé Depression. Mo in dust from the Bodélé Depression was measured with an average concentration of 1.14 ± 0.05 μg/g, similar to the crustal abundance. The model predicts Mo inputs from sea-salt aerosols in coastal regions up to 0.002 mg m-2yr-1. Significant sea-salt deposition occurs up to 300 km inland. Mo from fossil fuel combustion and biomass burning were also evaluated to determine the potential influence of anthropogenic emissions on releasing Mo into the environment.

  11. Environmental controls on coastal coarse aerosols: implications for microbial content and deposition in the near-shore environment.

    PubMed

    Dueker, M Elias; Weathers, Kathleen C; O'Mullan, Gregory D; Juhl, Andrew R; Uriarte, Maria

    2011-04-15

    Coarse aerosols (particle diameter (D(p)) > 2 μm) produced in coastal surf zones carry chemical and microbial content to shore, forming a connection between oceanic, atmospheric, and terrestrial systems that is potentially relevant to coastal ecology and human health. In this context, the effects of tidal height, wind speed, and fog on coastal coarse aerosols and microbial content were quantified on the southern coast of Maine, USA. Aerosols at this site displayed clear marine influence and had high concentrations of ecologically relevant nutrients. Coarse aerosol concentrations significantly increased with tidal height (i.e., decreasing distance from waterline), onshore wind speed, and fog presence. As onshore wind speeds rose above 3 m s(-1), the mean half-deposition distance of coarse aerosols increased to an observed maximum of 47.6 ± 10.9 m from the water's edge at wind speeds from 5.5-8 m s(-1). Tidal height and fog presence did not significantly influence total microbial aerosol concentrations but did have a significant effect on culturable microbial aerosol fallout. At low wind speeds, culturable microbial aerosols falling out near-shore decreased by half at a distance of only 1.7 ± 0.4 m from the water's edge, indicating that these microbes may be associated with large coarse aerosols with rapid settling rates.

  12. High T(sub c) superconductors fabricated by plasma aerosol mist deposition technique

    NASA Technical Reports Server (NTRS)

    Wang, X. W.; Vuong, K. D.; Leone, A.; Shen, C. Q.; Williams, J.; Coy, M.

    1995-01-01

    We report new results on high T(sub c) superconductors fabricated by a plasma aerosol mist deposition technique, in atmospheric environment. Materials fabricated are YBaCuO, BiPbSrCaCuO, BaCaCuO precursor films for TlBaCaCuO, and other buffers such as YSZ. Depending on processing conditions, sizes of crystallites and/or particles are between dozens of nano-meters and several micrometers. Superconductive properties and other material characteristics can also be tailored.

  13. Stratigraphy and sedimentology of a dry to wet eolian depositional system, Burns formation, Meridiani Planum, Mars

    NASA Astrophysics Data System (ADS)

    Grotzinger, J. P.; Arvidson, R. E.; Bell, J. F.; Calvin, W.; Clark, B. C.; Fike, D. A.; Golombek, M.; Greeley, R.; Haldemann, A.; Herkenhoff, K. E.; Jolliff, B. L.; Knoll, A. H.; Malin, M.; McLennan, S. M.; Parker, T.; Soderblom, L.; Sohl-Dickstein, J. N.; Squyres, S. W.; Tosca, N. J.; Watters, W. A.

    2005-11-01

    Outcrop exposures of sedimentary rocks at the Opportunity landing site (Meridiani Planum) form a set of genetically related strata defined here informally as the Burns formation. This formation can be subdivided into lower, middle, and upper units which, respectively, represent eolian dune, eolian sand sheet, and mixed eolian sand sheet and interdune facies associations. Collectively, these three units are at least 7 m thick and define a "wetting-upward" succession which records a progressive increase in the influence of groundwater and, ultimately, surface water in controlling primary depositional processes. The Burns lower unit is interpreted as a dry dune field (though grain composition indicates an evaporitic source), whose preserved record of large-scale cross-bedded sandstones indicates either superimposed bedforms of variable size or reactivation of lee-side slip faces by episodic (possibly seasonal) changes in wind direction. The boundary between the lower and middle units is a significant eolian deflation surface. This surface is interpreted to record eolian erosion down to the capillary fringe of the water table, where increased resistance to wind-induced erosion was promoted by increased sediment cohesiveness in the capillary fringe. The overlying Burns middle unit is characterized by fine-scale planar-laminated to low-angle-stratified sandstones. These sandstones accumulated during lateral migration of eolian impact ripples over the flat to gently undulating sand sheet surface. In terrestrial settings, sand sheets may form an intermediate environment between dune fields and interdune or playa surfaces. The contact between the middle and upper units of the Burns formation is interpreted as a diagenetic front, where recrystallization in the phreatic or capillary zones may have occurred. The upper unit of the Burns formation contains a mixture of sand sheet facies and interdune facies. Interdune facies include wavy bedding, irregular lamination with

  14. Long-Term Wet and Dry Deposition of Total and Methyl Mercury in the Remote Boreal Ecoregion of Canada

    SciTech Connect

    Graydon, Jennifer A; Louis, Vincent; Hintelmann, Holger; Lindberg, Steven Eric

    2008-11-01

    Although a positive relationship between atmospheric loadings of inorganic mercury (Hg(II)) to watersheds and concentrations of methyl mercury (MeHg) in fish has now been established, net wet and dry deposition of Hg(II) and MeHg to watersheds remains challenging to quantify. In this study, concentrations and loadings of total mercury (THg; all forms of Hg in a sample) and MeHg in open area wet deposition, throughfall, and litterfall were quantified at the remote Experimental Lakes Area in the boreal ecoregion, NW Ontario, Canada. Between 1992 and 2006, mean annual THg and MeHg loadings in the open were 36 17 and 0.5 0.2 mg ha 1, respectively. Throughfall THg and MeHg loadings were generally 2 4 times and 0.8 2 times higher, respectively, than loadings in the open. Loadings of both THg and MeHg were highest under an old growth spruce/fir canopy and lowest under a deciduous maple canopy, whereas loadings under young jack pine and wetland spruce/pine/alder canopies were intermediate. Litterfall generally represented the largest input of THg (86 105 mg ha 1) and MeHg (0.7 0.8 mg ha 1) to the landscape on an annual basis. Using the direct method of estimating dry deposition (thoughfall + litterfall open loadings), we calculated that annual dry deposition of THg and MeHg under forest canopies ranged from 105 to 201 mg ha 1, whereas dry deposition of MeHg ranged from 0.7 to 1.2 mg ha 1. Photoreduction and emission of wet-deposited Hg(II) from canopy foliage were accounted for, resulting in 3 5% (5 6 mg ha 1) higher annual estimates of dry deposition than via the direct method alone. Net THg and MeHg loadings to this remote landscape were lower than at any other previously studied forested site globally. This study shows that THg and MeHg loading can be extremely variable within a heterogeneous boreal landscape and that processes such as Hg photoreduction and emission from foliage should be considered when estimating dry deposition of Hg.

  15. Single-Species Aerosol Coagulation and Deposition with Arbitrary Size Resolution.

    SciTech Connect

    SAJO, ERNO

    2012-07-31

    Version 00 SAEROSA solves the dynamic aerosol coagulation and deposition problem with arbitrary computational precision under a variety of conditions. The code includes numerous user-selectable coagulation kernels, alone or in combinations, and permits an arbitrary initial size distribution. Many parameter combinations and what-if scenarios under user control are possible. The output gives the particle size distribution suspended in the carrier fluid initially and after the desired aerosol aging time in terms of both differential and integral aerosol volume concentrations. An auxiliary routine designed for the Mac OSX environment provides plotting capability. The output can be further processed by e.g., spreadsheets. The code has been benchmarked against three computer models, including MAEROS, and analytical models with excellent agreement. The test cases also included scenarios where previously published computational coagulation models lack capabilities or exhibit numerical instabilities. These included narrow, delta function, and non-lognormal initial size distributions, and further conditions, such as the presence of simultaneous coagulation mechanisms, including electrostatic effects, spanning multiple flow-regimes.

  16. Regional Scale Photochemical Model Evaluation of Total Mercury Wet Deposition and Speciated Ambient Mercury

    EPA Science Inventory

    Methylmercury is a known neurotoxin with deleterious health effects on humans and wildlife. Atmospheric deposition is the largest source of mercury loading to most terrestrial and aquatic ecosystems. Regional scale air quality models are needed to quantify mercury deposition resu...

  17. Microstructure and chemical wet etching characteristics of AlN films deposited by ac reactive magnetron sputtering

    SciTech Connect

    Tanner, S. M.; Felmetsger, V. V.

    2010-01-15

    The influence of the surface morphology of a molybdenum underlayer on the crystallinity and etchability of reactively sputtered c-axis oriented aluminum nitride thin films was investigated. Atomic force microscopy, scanning electron microscopy, transmission electron microscopy, high resolution x-ray diffraction, and defect selective chemical etching were used to characterize the microstructure of the Mo and AlN films. 1000 nm thick films of AlN with a full width at half maximum (FWHM) of the x-ray rocking curve ranging from 1.1 deg. to 1.9 deg. were deposited on 300 nm thick Mo underlayers with a FWHM of around 1.5 deg. The Ar pressure during the Mo deposition had a critical effect on the Mo film surface morphology, affecting the structure of the subsequently deposited AlN films and, hence, their wet etching characteristics. AlN films deposited on Mo sputtered at a relatively high pressure could not be etched completely, while AlN films deposited on low pressure Mo etched more easily. Postdeposition etching of the Mo surface in Ar rf discharge prior to deposition of the AlN film was found to influence the formation of AlN residuals that were difficult to etch. Optimal rf plasma etching conditions were found, which minimized the formation of these residuals.

  18. Depositional phasing of volcanic aerosols in the WAIS Divide ice core over the past 2400 years

    NASA Astrophysics Data System (ADS)

    Koffman, B. G.; Kreutz, K. J.; Breton, D. J.; Dunbar, N. W.; Kurbatov, A.

    2011-12-01

    Explosive volcanic events originating in the tropics are an intermittent but significant factor in climate forcing, with the potential to cause global cooling for up to several years. Evidence of prehistoric eruptions in the form of tephra has been documented in sedimentary records throughout the globe, including the polar ice sheets. The chemical record of volcanic aerosols is also found in ice core records. While the record of tropical volcanism observed in Antarctic ice cores (based on sulfate deposition) is consistent regionally, little to no evidence of insoluble aerosols (ash particles) from tropical eruptions has been found. The upper 577 m (2400 years) of the WAIS Divide deep ice core (WDC06A) was melted using the UMaine WAIS Melt Monitor system, which allows accurate mm-scale depth co-registration of electrical conductivity and particle data, with subsequent collection of discrete samples for expanded particle, glaciochemical and geochemical analysis. The concentration and size distribution of microparticles were measured using a flow-through Klotz Abakus laser particle detector, developed by Ruth et al (2002) and calibrated with Coulter-Counter measurements. High-resolution analysis of ice spanning these volcanic intervals indicates that insoluble aerosols consistently arrive sooner than soluble aerosols (i.e., sulfate) at the WAIS Divide site (e.g., the Kuwae, Vanuatu eruption of ~1452 C.E.; Figure 1). We have observed this phasing difference for multiple tropical eruptions, including Agung (1963 C.E.), Krakatau/Tarawera (1886/1883), Tambora (1815), Kuwae (~1452) and Unknown (~1259). This phasing difference, which is on the order of 6-18 months, appears to be related to the eruptive column height and atmospheric transport of material.

  19. Dynamic growth and deposition of hygroscopic aerosols in the nasal airway of a 5-year-old child.

    PubMed

    Kim, Jong Won; Xi, Jinxiang; Si, Xiuhua A

    2013-01-01

    Hygroscopic growth within the human respiratory tract can be significant, which may notably alter the behavior and fate of the inhaled aerosols. The objective of this study is to evaluate the hygroscopic effects upon the transport and deposition of nasally inhaled fine-regime aerosols in children. A physiologically realistic nasal-laryngeal airway model was developed based on magnetic resonance imaging of a 5-year-old boy. Temperature and relative humidity field were simulated using the low Reynolds number k - ε turbulence model and chemical specie transport model under a spectrum of four thermo-humidity conditions. Particle growth and transport were simulated using a well validated Lagrangian tracking model coupled with a user-defined hygroscopic growth module. The subsequent aerosol depositions for the four inhalation scenarios were evaluated on a multiscale basis such as total, subregional, and cellular-level depositions. Results of this study show that a supersaturated humid environment is possible in the nasal turbinate region and can lead to significant condensation growth (d / d(0)  > 10) of nasally inhaled aerosols. Depositions in the nasal airway can also be greatly enhanced by condensation growth with appropriate inhalation temperature and humidity. For subsaturated and mild inhalation conditions, the hygroscopic effects were found to be nonsignificant for total depositions, while exerting a large impact upon localized depositions.

  20. Solubility of aerosol trace elements: Sources and deposition fluxes in the Canary Region

    NASA Astrophysics Data System (ADS)

    López-García, Patricia; Gelado-Caballero, María Dolores; Collado-Sánchez, Cayetano; Hernández-Brito, José Joaquín

    2017-01-01

    African dust inputs have important effects on the climate and marine biogeochemistry of the subtropical North Atlantic Ocean. The impact of dust inputs on oceanic carbon uptake and climate is dependent on total dust deposition fluxes as well as the bioavailability of nutrients and metals in the dust. In this work, the solubility of trace metals (Fe, Al, Mn, Co and Cu) and ions (Ca, sulphate, nitrate and phosphate) has been estimated from the analysis of a long-time series of 109 samples collected over a 3-year period in the Canary Islands. Solubility is primarily a function of aerosol origin, with higher solubility values corresponding to aerosols with more anthropogenic influence. Using soluble fractions of trace elements measured in this work, atmospheric deposition fluxes of soluble metals and nutrients have been calculated. Inputs of dissolved nutrients (P, N and Fe) have been estimated for the mixed layer. Considering that P is the limiting factor when ratios of these elements are compared with phytoplankton requirements, an increase of 0.58 nM of P in the mixed layer (∼150 m depth) and in a year can be estimated, which can support an increase of 0.02 μg Chla L-1 y-1. These atmospheric inputs of trace metals and nutrients appear to be significant relative to the concentrations reported in this region, especially during the summer months when the water column is more stratified and deep-water nutrient inputs are reduced.

  1. Mapping PET-measured triamcinolone acetonide (TAA) aerosol distribution into deposition by airway generation.

    PubMed

    Lee, Z; Berridge, M S; Finlay, W H; Heald, D L

    2000-04-10

    The three dimensional (3D) distribution of inhaled drugs was measured using Positron Emission Tomography (PET) (Berridge, M.S, Muswick, G.J., Lee, Z., Leisure, G.L., Nelson, A.D., Muzic, R.F. Jr., Miraldi, F., Heald, D.L., 1997. PET evaluation of Azmacort(R) ([C-11]triamcinolone acetonide) dose administration. J. Nucl. Med. 38 (5) Suppl., 4-5). Data analysis was based upon regional ratios or penetration indices. To improve the analytical usefulness and objectivity, labeled drug from dynamic PET images was mapped into 23 airway generations following a general framework from a SPECT-based methodology (Fleming, J.S., Nassim, M.A., Hashish, A.H., Bailey, A.G. , Conway, J., Holgate, S., Halson, P., Moore, E., Martonen, T.B., 1995. Description of pulmonary deposition of radiolabeled aerosol by airway generation using a conceptual three dimensional model of lung morphology. J. Aerosol Med. 8, 341-356). A recently developed airway network model was used in this study. Quantitative PET scans of [C-11]triamcinolone acetonide distribution in the lung were determined following administration of Azmacort(R), a commercial metered dose inhaler with an integrated spacer device. Distributions at varying time periods after drug administration were investigated to explore the dynamics and kinetics of the aerosolized drug. Initially, deposition of labeled drug on conducting airways (generations 1-14) was found to be higher than those on acinar airways (generation 15-23), 64% versus 36%. The distribution pattern changed slowly with time. By 47 min, 51% of the dose remaining in the lung was found on conducting airways while 49% was on acinar airways. This study illustrates the value of PET imaging for the evaluation and design of drug formulations.

  2. Analysis of the Sensitivity of GEM-MACH PM2.5 Forecasts to the Representation of Wet and Dry Deposition Processes

    NASA Astrophysics Data System (ADS)

    Pavlovic, Radenko; Gong, Wanmin; Moran, Mike; Menard, Sylvain; Anselmo, David; Davignon, Didier

    2014-05-01

    Environment Canada produces 48-hour operational air quality forecasts for Canada twice daily (at 00 and 12 UTC). At the core of the forecast system is the GEM-MACH model, an on-line coupled meteorology and chemistry model that considers gas-phase, aqueous-phase, and heterogeneous chemistry and a number of size-resolved particulate matter (PM) processes, including wet and dry deposition. Predicting PM concentrations, especially for fine particular matter (PM2.5), remains a challenge for air quality models. In this poster we analyze the maximum sensitivity of predicted PM2.5 concentrations to the representation of both wet and dry deposition. For wet deposition, both in-cloud and below-cloud scavenging are considered. An analysis of the impact of wet and dry deposition on PM2.5 concentrations was performed using GEM-MACH model output over the summer and winter seasons of 2012 for a base case and two sensitivity runs, one in which the parameterization of dry deposition was turned off and one in which the parameterization of wet deposition was turned off. The results obtained show that the predicted wet deposition of PM2.5 over North America is generally greater than predicted dry deposition, but both processes can reduce predicted PM2.5 concentration by 25% or more on average. However, the impact of both processes varies significantly from one region to another and is strongly dependent on modelled meteorology, especially the occurrence of precipitation. These results suggest that the details of the treatments of wet and dry deposition of PM2.5 do matter and can enhance or detract from model performance.

  3. Implementation and evaluation of pH-dependent cloud chemistry and wet deposition in the chemical transport model REM-Calgrid

    NASA Astrophysics Data System (ADS)

    Banzhaf, S.; Schaap, M.; Kerschbaumer, A.; Reimer, E.; Stern, R.; van der Swaluw, E.; Builtjes, P.

    2012-03-01

    The Chemistry Transport Model REM-Calgrid (RCG) has been improved by implementing an enhanced description of aqueous-phase chemistry and wet deposition processes including droplet pH. A sensitivity study on cloud and rain droplet pH has been performed to investigate its impact on model sulphate production and gas wet scavenging. Air concentrations and wet deposition fluxes of the model sensitivity runs have been analysed and compared to observations. It was found that droplet pH variation within atmospheric ranges affects modelled air concentrations and wet deposition fluxes significantly. Applying a droplet pH of 5.5 for July 2005, mean sulphate air concentrations increased by up to 10% compared to using a droplet pH of 5 while SO2 domain wet deposition sum increased by 110%. Moreover, model results using modelled droplet pH for January and July 2005 have been compared to model results applying a constant pH of 5 and to observations. The comparison to observations has shown that using a variable droplet pH improves the model performance concerning air concentrations and wet deposition fluxes of the investigated sulphur and nitrogen compounds. For SOx wet deposition fluxes the Root Mean Square Error (RMSE) decreased by 16% for July 2005 when using a variable droplet pH instead of a constant pH of 5. Concerning sulphate and SO2 air concentrations the RMSE was reduced by 8% and 16% for July 2005, respectively. The results have revealed that applying a variable droplet pH is preferable to using a constant pH leading to better consistency concerning air concentrations and wet deposition fluxes.

  4. Mechanical and in vitro biological performances of hydroxyapatite-carbon nanotube composite coatings deposited on Ti by aerosol deposition.

    PubMed

    Hahn, Byung-Dong; Lee, Jung-Min; Park, Dong-Soo; Choi, Jong-Jin; Ryu, Jungho; Yoon, Woon-Ha; Lee, Byoung-Kuk; Shin, Du-Sik; Kim, Hyoun-Ee

    2009-10-01

    Hydroxyapatite (HA)-carbon nanotube (CNT) composite coatings on Ti plate, produced by aerosol deposition using HA-CNT powders, were developed for biomedical applications. For the deposition process HA-CNT powder mixtures with CNT contents of 1 and 3 wt.% were used. Dense coatings with a thickness of 5 microm were fabricated, irrespective of the content of CNTs. No pores or microcracks were observed in the coatings. The coatings had good adhesion to the substrate, exhibiting a high adhesion strength, ranging from 27.3 to 29.0 MPa. Microstructural observation using field-emission gun scanning electron microscopy and transmission electron microscopy showed that CNTs with a typical tubular structure were found in the HA-CNT composite coatings. Nanoindentation tests revealed that the mechanical properties, such as the hardness and elastic modulus, were significantly improved by the addition of the CNTs to the HA coating. In addition, the proliferation and alkaline phosphatase (ALP) activity of MC3T3-E1 pre-osteoblast cells grown on the HA-CNT composite coatings were higher than those on the bare Ti and pure HA coating. The ALP activity of the composite coatings considerably improved as the CNT content increased. These results suggest that CNTs would be an effective reinforcing agent to enhance both the mechanical and biological performances of HA coatings.

  5. Enhanced Bactericidal Activity of Silver Thin Films Deposited via Aerosol-Assisted Chemical Vapor Deposition.

    PubMed

    Ponja, Sapna D; Sehmi, Sandeep K; Allan, Elaine; MacRobert, Alexander J; Parkin, Ivan P; Carmalt, Claire J

    2015-12-30

    Silver thin films were deposited on SiO2-barrier-coated float glass, fluorine-doped tin oxide (FTO) glass, Activ glass, and TiO2-coated float glass via AACVD using silver nitrate at 350 °C. The films were annealed at 600 °C and analyzed by X-ray powder diffraction, X-ray photoelectron spectroscopy, UV/vis/near-IR spectroscopy, and scanning electron microscopy. All the films were crystalline, and the silver was present in its elemental form and of nanometer dimension. The antibacterial activity of these samples was tested against Escherichia coli and Staphylococcus aureus in the dark and under UV light (365 nm). All Ag-deposited films reduced the numbers of E. coli by 99.9% within 6 h and the numbers of S. aureus by 99.9% within only 2 h. FTO/Ag reduced bacterial numbers of E. coli to below the detection limit after 60 min and caused a 99.9% reduction of S. aureus within only 15 min of UV irradiation. Activ/Ag reduced the numbers of S. aureus by 66.6% after 60 min and TiO2/Ag killed 99.9% of S. aureus within 60 min of UV exposure. More remarkably, we observed a 99.9% reduction in the numbers of E. coli within 6 h and the numbers of S. aureus within 4 h in the dark using our novel TiO2/Ag system.

  6. Modeling wet deposition of inorganics over Northeast Asia with MRI-PM/c and the effects of super large sea salt droplets at near-the-coast stations

    NASA Astrophysics Data System (ADS)

    Kajino, M.; Deushi, M.; Maki, T.; Oshima, N.; Inomata, Y.; Sato, K.; Ohizumi, T.; Ueda, H.

    2012-06-01

    We conducted a regional-scale simulation (with grid spacing = 60 km) over Northeast Asia for the entire year of 2006 by using an aerosol chemical transport model, the lateral and upper boundary concentrations of which we predicted with a global stratospheric and tropospheric chemistry-climate model, with a horizontal resolution of T42 (grid spacing ~300 km) and a time resolution of 1 h. The present one-way nested global-through-regional-scale model is called the Meteorological Research Institute - Passive-tracers Model system for atmospheric Chemistry (MRI-PM/c). We evaluated the model performance with respect to the major inorganic components in rain and snow measured by stations of the Acid Deposition Monitoring Network in East Asia (EANET). Through statistical analysis, we show that the model successfully reproduced the regional-scale processes of emission, transport, transformation, and wet deposition of major inorganic species derived from anthropogenic and natural sources, including SO42-, NH4+, NO3-, Na+ and Ca2+. Interestingly, the only exception was Na+ in precipitation at near-coastal stations (where the distance from the coast was from 150 to 700 m), concentrations of which were significantly underestimated by the model, by up to a factor of 30. This result suggested that the contribution of short-lived, super-large sea salt droplets (SLSD; D > 10-100 μm) was substantial in precipitation samples at stations near the coast of Japan; thus samples were horizontally representative only within the traveling distances of SLSD (from 1 to 10 km). Nevertheless, the calculated effect of SLSD on precipitation pH was very low, a change of about +0.014 on average, even if the ratio of SLSD to all sea salt in precipitation was assumed to be 90%.

  7. Aerosol and Surface Deposition Characteristics of Two Surrogates for Bacillus anthracis Spores.

    PubMed

    Bishop, Alistair H; Stapleton, Helen L

    2016-11-15

    Spores of an acrystalliferous derivative of Bacillus thuringiensis subsp. kurstaki, termed Btcry-, are morphologically, aerodynamically, and structurally indistinguishable from Bacillus anthracis spores. Btcry- spores were dispersed in a large, open-ended barn together with spores of Bacillus atrophaeus subsp. globigii, a historically used surrogate for Bacillus anthracis Spore suspensions (2 × 10(12) CFU each of B. atrophaeus subsp. globigii and Btcry-) were aerosolized in each of five spray events using a backpack misting device incorporating an air blower; a wind of 4.9 to 7.6 m s(-1) was also flowing through the barn in the same direction. Filter air samplers were situated throughout the barn to assess the aerosol density of the spores during each release. Trays filled with a surfactant in aqueous buffer were placed on the floor near the filter samplers to assess spore deposition. Spores were also recovered from arrays of solid surfaces (concrete, aluminum, and plywood) that had been laid on the floor and set up as a wall at the end of the barn. B. atrophaeus subsp. globigii spores were found to remain airborne for significantly longer periods, and to be deposited on horizontal surfaces at lower densities, than Btcry- spores, particularly near the spray source. There was a 6-fold-higher deposition of Btcry- spores than of B. atrophaeus subsp. globigii spores on vertical surfaces relative to the surrounding airborne density. This work is relevant for selecting the best B. anthracis surrogate for the prediction of human exposure, hazard assessment, and hazard management following a malicious release of B. anthracis IMPORTANCE: There is concern that pathogenic bacteria could be maliciously disseminated in the air to cause human infection and disruption of normal life. The threat from spore-forming organisms, such as the causative agent of anthrax, is particularly serious. In order to assess the extent of this risk, it is important to have a surrogate organism

  8. Atmospheric wet deposition of nitrogen and sulfur to a typical red soil agroecosystem in Southeast China during the ten-year monsoon seasons (2003-2012)

    NASA Astrophysics Data System (ADS)

    Cui, Jian; Zhou, Jing; Peng, Ying; He, Yuanqiu; Yang, Hao; Mao, Jingdong

    2014-01-01

    Biological processes in agroecosystems have been affected by atmospheric nitrogen (N) and sulfur (S) deposition, but there is uncertainty about their deposition characteristics in the monsoon season. We collected rain samples using an ASP-2 sampler, recorded rainfall and rain frequency by an auto-meteorological experiment sub-station, and determined total N, NO3--N and NH4+-N levels in precipitation with an AutoAnalyzer 3 and SO42--S with a chromatography, in order to characterize the wet deposition of N and S to a typical red soil agroecosystem by a ten-year monitoring experiment in Southeast China. The results indicated that N and S wet deposition had an increased trend with the flux of total N (3.34-65.17 kg ha-1 N) and total S (SO42--S) (7.17-23.44 kg ha-1 S) during the monsoon seasons. The additional applications of pig mature in 2006 and 2007 led to the peaks of DON (dissolved organic nitrogen) and total N wet deposition. On average, NH4+-N was the major N form, accounting for 48.5% of total N wet deposition and DON was not a negligible N form, accounting for 20.8% during the ten-year monsoon seasons (except 2006 and 2007). Wet deposition of N and S has been intensively influenced by human activities in the monsoon season, and would increase the potential ecological risk in the red soil agricultural ecosystem.

  9. Yttrium Iron Garnet Thick Films Formed by the Aerosol Deposition Method for Microwave Inductors

    NASA Astrophysics Data System (ADS)

    Johnson, Scooter; Newman, Harvey; Glaser, E. R.; Cheng, Shu-Fan; Tadjer, Marko; Kub, Fritz; Eddy, Charles, Jr.

    2014-03-01

    We have employed the aerosol deposition method (ADM) to direct-write 40 μm-thick polycrystalline films of yttrium iron garnet (YIG, Y3Fe5O12) at room temperature onto patterned gold inductors on sapphire substrates at a deposition rate of 1-3 μm/min as a first step toward integration into microwave magnetic circuits. A challenge to integrating magnetic films into current semiconductor technology is the high-temperature regime (900-1400°C) at which conventional ferrite preparation takes place. The ability of the ADM to form dense, thick films at room temperature makes this a promising approach for integrated magnetics where low-temperature deposition and thick films are required. The ADM YIG film has an rms roughness of 3-4 μm, is comprised of nano-crystalline grains with a density 50% of the theoretical value. XRD patterns of the as-deposited film and starting powder indicate a polycrystalline single-phase film. In-plane VSM and FMR measurements reveal a saturation of 22 emu/g, coercivity of 27 Oe, and linewidth of 360 Oe. Early measurements of air-filled and YIG-filled gold inductors between 0.01-10 GHz indicate an improved inductance of nearly a factor of 2 at low frequency. At higher frequency, resonance effects diminish this improvement. This work is sponsored by the Office of Naval Research under program number N0001413WX20845 (Dr. Daniel Green, Program Manager).

  10. Use of multivariate analysis for determining sources of solutes found in wet atmospheric deposition in the United States

    USGS Publications Warehouse

    Hooper, R.P.; Peters, N.E.

    1989-01-01

    A principal-components analysis was performed on the major solutes in wet deposition collected from 194 stations in the United States and its territories. Approximately 90% of the components derived could be interpreted as falling into one of three categories - acid, salt, or an agricultural/soil association. The total mass, or the mass of any one solute, was apportioned among these components by multiple linear regression techniques. The use of multisolute components for determining trends or spatial distribution represents a substantial improvement over single-solute analysis in that these components are more directly related to the sources of the deposition. The geographic patterns displayed by the components in this analysis indicate a far more important role for acid deposition in the Southeast and intermountain regions of the United States than would be indicated by maps of sulfate or nitrate deposition alone. In the Northeast and Midwest, the acid component is not declining at most stations, as would be expected from trends in sulfate deposition, but is holding constant or increasing. This is due, in part, to a decline in the agriculture/soil factor throughout this region, which would help to neutralize the acidity.

  11. Application of both a physical theory and statistical procedure in the analyses of an in vivo study of aerosol deposition

    SciTech Connect

    Cheng, K.H.; Swift, D.L.; Yang, Y.H.

    1995-12-01

    Regional deposition of inhaled aerosols in the respiratory tract is a significant factor in assessing the biological effects from exposure to a variety of environmental particles. Understanding the deposition efficiency of inhaled aerosol particles in the nasal and oral airways can help evaluate doses to the extrathoracic region as well as to the lung. Dose extrapolation from laboratory animals to humans has been questioned due to significant physiological and anatomical variations. Although human studies are considered ideal for obtaining in vivo toxicity information important in risk assessment, the number of subjects in the study is often small compared to epidemiological and animal studies. This study measured in vivo the nasal airway dimensions and the extrathoracic deposition of ultrafine aerosols in 10 normal adult males. Variability among individuals was significant. The nasal geometry of each individual was characterized at a resolution of 3 mm using magnetic resonance imaging (MRI) and acoustic rhinometry (AR). The turbulent diffusion theory was used to describe the nonlinear nature of extrathoracic aerosol deposition. To determine what dimensional features of the nasal airway were responsible for the marked differences in particle deposition, the MIXed-effects NonLINear Regression (MIXNLIN) procedure was used to account for the random effort of repeated measurements on the same subject. Using both turbulent diffusion theory and MIXNLIN, the ultrafine particle deposition is correlated with nasal dimensions measured by the surface area, minimum cross-sectional area, and complexity of the airway shape. The combination of MRI and AR is useful for characterizing both detailed nasal dimensions and temporal changes in nasal patency. We conclude that a suitable statistical procedure incorporated with existing physical theories must be used in data analyses for experimental studies of aerosol deposition that involve a relatively small number of human subjects.

  12. Massive volcanic SO(2) oxidation and sulphate aerosol deposition in Cenozoic North America.

    PubMed

    Bao, Huiming; Yu, Shaocai; Tong, Daniel Q

    2010-06-17

    Volcanic eruptions release a large amount of sulphur dioxide (SO(2)) into the atmosphere. SO(2) is oxidized to sulphate and can subsequently form sulphate aerosol, which can affect the Earth's radiation balance, biologic productivity and high-altitude ozone concentrations, as is evident from recent volcanic eruptions. SO(2) oxidation can occur via several different pathways that depend on its flux and the atmospheric conditions. An investigation into how SO(2) is oxidized to sulphate-the oxidation product preserved in the rock record-can therefore shed light on past volcanic eruptions and atmospheric conditions. Here we use sulphur and triple oxygen isotope measurements of atmospheric sulphate extracted from tuffaceous deposits to investigate the specific oxidation pathways from which the sulphate was formed. We find that seven eruption-related sulphate aerosol deposition events have occurred during the mid-Cenozoic era (34 to 7 million years ago) in the northern High Plains, North America. Two extensively sampled ash beds display a similar sulphate mixing pattern that has two distinct atmospheric secondary sulphates. A three-dimensional atmospheric sulphur chemistry and transport model study reveals that the observed, isotopically discrete sulphates in sediments can be produced only in initially alkaline cloudwater that favours an ozone-dominated SO(2) oxidation pathway in the troposphere. Our finding suggests that, in contrast to the weakly acidic conditions today, cloudwater in the northern High Plains may frequently have been alkaline during the mid-Cenozoic era. We propose that atmospheric secondary sulphate preserved in continental deposits represents an unexploited geological archive for atmospheric SO(2) oxidation chemistry linked to volcanism and atmospheric conditions in the past.

  13. Influence of development stage of spring oilseed rape and spring wheat on interception of wet-deposited radiocaesium and radiostrontium

    NASA Astrophysics Data System (ADS)

    Bengtsson, S. B.; Eriksson, J.; Gärdenäs, A. I.; Rosén, K.

    2012-12-01

    The dry and wet deposition of radionuclides released into the atmosphere can be intercepted by vegetation in terrestrial ecosystems. The aim of this study was to quantify the interception of wet deposited 134Cs and 85Sr by spring oilseed rape (Brassíca napus L.) and spring wheat (Tríticum aestívum L.). The dependency of the intercepted fraction (f) on total above ground plant biomass, growing stage and the Leaf Area Index (LAI) was quantified. A trial was established in Uppsala (east central Sweden), with land management in accordance to common agricultural practices. The field trial was a randomised block design of 1 × 1 m2 parcels with three replicates. During the growing season of 2010, a rainfall simulator deposited 134Cs and 85Sr during six different growth stages. Two to 3 h after deposition, the biomass of the centre 25 × 25 cm2 area of each parcel was sampled and above ground biomass and LAI were measured. The radioactivity concentration and radioactivity of samples were measured by High Purity Germanium (HPGe)-detectors. For 134Cs, there was a correlation between f and LAI (r2 = 0.55, p < 0.05) for spring wheat, but not for spring oilseed rape (r2 = 0.28, p > 0.05). For 85Sr, there was a correlation between f and LAI for both crops (r2 = 0.41, p < 0.05 for spring oilseed rape and r2 = 0.48 p, <0.05 for spring wheat). There was no correlation between f and above ground plant biomass in spring oilseed rape for either 134Cs (r2 = 0.01, p > 0.05) or for 85Sr (r2 = 0.11, p > 0.05). For spring wheat, there was a correlation for both 134Cs (r2 = 0.36, p < 0.05) and 85Sr (r2 = 0.32, p < 0.05). For spring oilseed rape, f was highest at growth stage 'stem elongation' for 134Cs (0.32 ± 0.22) and 85Sr (0.41 ± 0.29). For spring wheat, f was highest at growth stage 'ripening' for both radionuclides (134Cs was 0.36 ± 0.14 and 85Sr was 0.48 ± 0.18). Thus, LAI can be used to quantify interception of both radionuclides for both crops, whereas, above ground plant

  14. Atmospheric wet deposition of dissolved trace elements to Jiaozhou Bay, North China: Fluxes, sources and potential effects on aquatic environments.

    PubMed

    Xing, Jianwei; Song, Jinming; Yuan, Huamao; Wang, Qidong; Li, Xuegang; Li, Ning; Duan, Liqin; Qu, Baoxiao

    2017-05-01

    To analyze the fluxes, seasonal variations, sources and potential ecological effects of dissolved trace elements (TEs) in atmospheric wet deposition (AWD), one-year wet precipitation samples were collected and determined for nine TEs in Jiaozhou Bay (JZB) between June 2015 and May 2016. Both the volume-weighted mean (VWM) concentration and flux sequence for the measured TEs was Al > Mn > Zn > Fe > Pb > Se > Cr > Cd > Co. Al was the most abundant TE with a VWM concentration and wet flux of 33.8 μg L(-1) and 29.2 mg m(-2) yr(-1), which were 2 and 3 orders of magnitude higher than those of Co, respectively. The emission intensities of pollutants, rainfall amount and wind speed were the dominating factors influencing seasonal variations of TEs in AWD. Based on enrichment factors, correlation analysis and principal component analysis, most of the TEs in AWD were primarily originated from anthropogenic activities except for Al and Fe, which are typically derived from re-suspended soil dusts. Although the TE inputs by AWD were significantly lower than those by rivers, the TE inputs via short-term heavy rains would distinctly increase surface seawater TE concentrations and then pollute the marine environment of JZB. AWD would have both profound impacts on the biogeochemical cycles of TEs and dual ecological effects (nutrient and toxicity) on aquatic organisms.

  15. Wet acid deposition in Chinese natural and agricultural ecosystems: Evidence from national-scale monitoring

    NASA Astrophysics Data System (ADS)

    Yu, Haili; He, Nianpeng; Wang, Qiufeng; Zhu, Jianxing; Xu, Li; Zhu, Zhilin; Yu, Guirui

    2016-09-01

    Acid deposition in precipitation has received widespread attention. However, it is necessary to monitor the acid deposition in Chinese agricultural and natural ecosystems because data derived from traditional urban/suburban observations might overestimate it to some extent. In this study, we continuously measured the acid deposition through precipitation (pH, sulfate (SO42-), and nitrate (NO3-)) in 43 field stations from 2009 to 2014 to explore the spatial patterns and the main influencing factors of acid deposition in Chinese agricultural and natural ecosystems. The results showed that the average precipitation pH at the 43 stations varied between 4.10 and 8.25 (average: 6.2) with nearly 20% of the observation sites being subjected to acid precipitation (pH < 5.6). The average deposition of SO42- and NO3- was 115.99 and 32.93 kg ha-1 yr-1, respectively. An apparent regional difference of acid deposition in Chinese agricultural and natural ecosystems was observed, which was most serious in south and central China and less serious in northwest China, Inner Mongolia, and Qinghai-Tibet. The level of economic development and amount of precipitation could explain most of the spatial variations of pH, SO42-, and NO3- depositions. It is anticipated that acid deposition might increase further, although the current level of acid deposition in these Chinese agricultural and natural ecosystems was found to be less serious than projected from urban/suburban data. The control of energy consumption should be strengthened in future to prevent an increase of acid deposition in China.

  16. Coalescence of fog droplets: Differential fog water deposition on wet and dry forest canopies

    NASA Astrophysics Data System (ADS)

    Tobón, C.; Barrero, J.

    2010-07-01

    The Páramo ecosystem is a high-altitude (2800 - 4500 masl), natural ecosystems which comprises approximately 42000 km2, extending across the Andes from north of Peru, Ecuador, Colombia and western part of Venezuela. Andean páramos are widely considered to be prime suppliers of large volumes of high-quality water for large cities and for hydropower production. As páramos tend to be subjected to persistent fog incidence, fog interception by the vegetation is a common process in these ecosystems, representing not only an extra input of water to the ecosystem but also to suppress evaporation. In this process, small drops of water, transported by the wind, are captured by the surfaces of the vegetation, acting as physical obstacles to the flow of fog. These drops condense in the exposed surfaces and drip towards the ground or evaporate from the surfaces. The quantification of the magnitude of these processes is important for the quantification of the water balance of river basins where these types of ecosystems exist. Although the great hydrological importance of fog in montane tropical ecosystems little is known about its physical principles related to the interception of fog by physical barriers as vegetation, notably the differential behaviour of a wet and dry vegetation in the efficiency of capturing water from the fog. To characterize and quantify this efficiency of páramo vegetation in capturing water from the fog, during wet and dry canopy conditions, an experimental design was set up at the Páramo de Chingaza (Colombia) where paired samples of espeletia branches (dry and wet) were exposed to different fog events, and at the same time Juvik cylinders were exposed by the side of the experimental site, to measured fog inputs. Cylinders were also paired (wet and dry) at the beginning of the experiments. Results indicated that exposed wet and dry samples have a significant difference on the magnitude of water intercepted from the fog, being, in average, the wet

  17. Liu et al. suspect that Zhu et al. (2015) may have underestimated dissolved organic nitrogen (N) but overestimated total particulate N in wet deposition in China.

    PubMed

    Liu, Xuejun; Xu, Wen; Pan, Yuepeng; Du, Enzai

    2015-07-01

    In a recent publication in the journal Science of the Total Environment, Zhu et al. (2015) reported the composition, spatial patterns, and factors influencing atmospheric wet nitrogen (N) deposition based on one year's data from 41-monitoring sites in China. We suspect their results may largely underestimate dissolved organic N (DON) but overestimate total particulate N (TPN) in wet deposition due to the uncertainty resulting from the sampling, storage and analysis methods in their study. Our suspicions are based mainly on our experience from earlier measurements and the literature. We therefore suggest that enhanced data quality control on atmospheric N deposition measurements should be taken into account in future studies.

  18. Patterns of wet deposition of acidic matter in Maryland: January-June 1984. Final report

    SciTech Connect

    Maxwell, C.; Bartoshesky, J.; Pfeffer, N.; Campbell, S.

    1987-03-03

    A data base containing precipitation-chemistry data collected by multiple monitoring programs in and around Maryland for the January through June 1984 time period was compiled. Isopleth maps were constructed showing the spatial variation in the precipitation concentrations and depositions of hydrogen ion, sulfate, nitrate, ammonium, calcium, sodium, chloride, potassium, and magnesium. For each parameter, the concentration pattern was very similar to its deposition pattern. The patterns suggest the occurrence of a ridge of high sulfate, nitrate, and hydrogen ion concentrations and depositions extending from south-central Pennsylvania, south into Maryland along the western shore of the Chesapeake Bay.

  19. Transport characteristics of aerosol from urban point sources

    NASA Astrophysics Data System (ADS)

    Kunkel, Daniel; Lawrence, Mark G.; Kerkweg, Astrid; Tost, Holger; Jöckel, Patrick; Borrmann, Stephan

    2010-05-01

    Urban aerosols are an important source of regional and global air pollution. The local buildup, long-range transport, and dry and wet deposition of aerosols depend strongly on the aerosol size distribution and on the regional meteorological characteristics. We examine the characteristics of urban aerosol dispersion based on simulations of monodisperse passive aerosol tracers with sizes of 0.1, 1.0, 2.5, and 10.0 μm, performed with the global chemistry circulation model EMAC (ECHAM5-MESSy-Atmospheric-Chemistry). 39 point sources were selected for the analysis, originating from major population centers (MPCs) around the world. All tracers, one for each source and size, have the same total, constant emission flux, and undergo dry and wet aerosol deposition. Sensitivity simulations are performed in which either there is no activation of the aerosol as cloud condensation nuclei (CCN), or all aerosol is activated as CCN. Using the same constant emission rate for each MPC allows us to compare how different large point sources pollute the atmosphere and the surface on different horizontal scales. The transport and deposition of the aerosol tracers from each MPC are quantitatively compared by the application of metrics. The analysis focuses on: the efficiency of short- and long-range horizontal transport; the fraction of tracer transported to the upper troposphere; and the fractions which are dry or wet deposited. Smaller particles with longer lifetimes (two to 14 days) are more effective at polluting remote locations (horizontal and vertical) and are deposited mostly by scavenging, while larger particles, with shorter lifetimes (several hours to a couple of days) more effectively pollute the environment nearby their source, and are most strongly removed by dry deposition from the atmosphere. By means of considering the same emission for each city, the presentation provides a detailed view of how aerosol tracers disperse and deposit on different spatial scales, depending

  20. Morphologies and wetting properties of copper film with 3D porous micro-nano hierarchical structure prepared by electrochemical deposition

    NASA Astrophysics Data System (ADS)

    Wang, Hongbin; Wang, Ning; Hang, Tao; Li, Ming

    2016-05-01

    Three-dimensional porous micro-nano hierarchical structure Cu films were prepared by electrochemical deposition with the Hydrogen bubble dynamic template. The morphologies of the deposited films characterized by Scanning Electronic Microscopy (SEM) exhibit a porous micro-nano hierarchical structure, which consists of three levels in different size scales, namely the honeycomb-like microstructure, the dendritic substructure and the nano particles. Besides, the factors which influenced the microscopic morphology were studied, including the deposition time and the additive Ethylene diamine. By measuring the water contact angle, the porous copper films were found to be super-hydrophobic. The maximum of the contact angles could reach as high as 162.1°. An empirical correlation between morphologies and wetting properties was revealed for the first time. The pore diameter increased simultaneously with the deposition time while the contact angle decreased. The mechanism was illustrated by two classical models. Such super-hydrophobic three-dimensional hierarchical micro-nano structure is expected to have practical application in industry.

  1. A multi-resolution assessment of the Community Multiscale Air Quality (CMAQ) model v4.7 wet deposition estimates for 2002-2006

    NASA Astrophysics Data System (ADS)

    Appel, K. W.; Foley, K. M.; Bash, J. O.; Pinder, R. W.; Dennis, R. L.; Allen, D. J.; Pickering, K.

    2011-05-01

    This paper examines the operational performance of the Community Multiscale Air Quality (CMAQ) model simulations for 2002-2006 using both 36-km and 12-km horizontal grid spacing, with a primary focus on the performance of the CMAQ model in predicting wet deposition of sulfate (SO4=), ammonium (NH4+) and nitrate (NO3-). Performance of the wet deposition estimates from the model is determined by comparing CMAQ predicted concentrations to concentrations measured by the National Acid Deposition Program (NADP), specifically the National Trends Network (NTN). For SO4= wet deposition, the CMAQ model estimates were generally comparable between the 36-km and 12-km simulations for the eastern US, with the 12-km simulation giving slightly higher estimates of SO4= wet deposition than the 36-km simulation on average. The result is a slightly larger normalized mean bias (NMB) for the 12-km simulation; however both simulations had annual biases that were less than ±15 % for each of the five years. The model estimated SO4= wet deposition values improved when they were adjusted to account for biases in the model estimated precipitation. The CMAQ model underestimates NH4+ wet deposition over the eastern US, with a slightly larger underestimation in the 36-km simulation. The largest underestimations occur in the winter and spring periods, while the summer and fall have slightly smaller underestimations of NH4+ wet deposition. The underestimation in NH4+ wet deposition is likely due in part to the poor temporal and spatial representation of ammonia (NH3) emissions, particularly those emissions associated with fertilizer applications and NH3 bi-directional exchange. The model performance for estimates of NO3- wet deposition are mixed throughout the year, with the model largely underestimating NO3- wet deposition in the spring and summer in the eastern US, while the model has a relatively small bias in the fall and winter. Model estimates of NO3- wet deposition tend to be slightly

  2. ATMOSPHERIC MERCURY SIMULATION USING THE CMAQ MODEL: FORMULATION DESCRIPTION AND ANALYSIS OF WET DEPOSITION RESULTS

    EPA Science Inventory

    The Community Multiscale Air Quality (CMAQ) modeling system has recently been adapted to simulate the emission, transport, transformation and deposition of atmospheric mercury in three distinct forms; elemental mercury gas, reactive gaseous mercury, and particulate mercury. Emis...

  3. Inorganic nitrogen wet deposition: Evidence from the North-South Transect of Eastern China.

    PubMed

    Zhan, X; Yu, G; He, N; Jia, B; Zhou, M; Wang, C; Zhang, J; Zhao, G; Wang, S; Liu, Y; Yan, J

    2015-09-01

    We examined the spatio-temporal variation of dissolved inorganic nitrogen (DIN) deposition in eight typical forest ecosystems of Eastern China for three consecutive years. DIN deposition exhibited an increasing gradient from north to south, with N-NH4(+) as the predominant contributor. DIN deposition in precipitation changed after interaction with the forest canopy, and serious ecological perturbations are expected in this region. DIN deposition presented seasonal fluctuations, which might be ascribed to agricultural activity, fossil-fuel combustion and environmental factors (i.e., wind direction, soil temperature). Notably, N fertilizer use (FN), energy consumption (E), and precipitation (P) jointly explained 84.3% of the spatial variation in DIN deposition, of which FN (27.2%) was the most important, followed by E (24.8%), and finally P (9.3%). The findings demonstrate that DIN deposition is regulated by precipitation mainly via anthropogenic N emissions, and this analysis provides decision-makers a novel view for N pollution abatement.

  4. AEROSOL DEPOSITION EFFICIENCIES AND UPSTREAM RELEASE POSITIONS FOR DIFFERENT INHALATION MODES IN AN UPPER BRONCHIAL AIRWAY MODELS

    EPA Science Inventory

    Aerosol Deposition Efficiencies and Upstream Release Positions for Different Inhalation Modes in an Upper Bronchial Airway Model

    Zhe Zhang, Clement Kleinstreuer, and Chong S. Kim

    Center for Environmental Medicine and Lung Biology, University of North Carolina at Ch...

  5. Characterization of Fe–Cr alloy metallic interconnects coated with LSMO using the aerosol deposition process

    SciTech Connect

    Huang, Jian-Jia; Fu, Yen-Pei; Wang, Jian-Yih; Cheng, Yung-Neng; Lee, Shyong; Hsu, Jin-Cherng

    2014-03-01

    Graphical abstract: - Highlights: • Lanthanum strontium manganite (LSMO) as the protective layer for metallic interconnects was successfully prepared by aerosol deposition method (AD). • The microstructure, electrical resistance and composition for LSMO-coated Fe–Cr alloys undergoing high temperature, long-hour oxidation were investigated. • The denser protective layer prepared by AD might effectively prohibit the growth of oxidized scale after long time running at 800 °C in air. - Abstract: A Fe–Cr alloy, used for metallic interconnects, was coated with a protective layer of lanthanum strontium manganite (LSMO) using the aerosol deposition method (AD). The effects of the LSMO protective layer, which was coated on the Fe–Cr interconnects using AD, on the area specific resistance (ASR) during high temperature oxidation and the Cr evaporation behaviors were systematically investigated in this paper. The microstructures, morphologies, and compositions of the oxidized scales that appeared on the LSMO-coated Fe–Cr alloy after annealing at 800 °C for 750 h in air were examined using SEM equipped with EDS. The EPMA mapping of the LSMO-coated Fe–Cr interconnects undergoing long term, high-temperature oxidation was used to explain the formation layers of the oxidized scale, which consists of (Mn,Cr){sub 3}O{sub 4} and Cr{sub 2}O{sub 3} layers. Moreover, the experimental results revealed that the AD process is a potential method for preparing denser protective layers with highly desirable electrical properties for metallic interconnects.

  6. Impacts of ENSO events on cloud radiative effects in preindustrial conditions: Changes in cloud fraction and aerosol emissions, wet scavenging and transport

    NASA Astrophysics Data System (ADS)

    Yang, Y.; Russell, L. M.; Xu, L.; Lou, S.; Lamjiri, M. A.

    2015-12-01

    The impacts of the El Niño-Southern Oscillation (ENSO) events on shortwave and longwave cloud radiative effects (CRESW and CRELW) and the related changes in cloud fraction and aerosol emissions, wet scavenging and transport are quantified using three 150-year simulations for the preindustrial condition from the CESM model. Compared to recent observations from Clouds and the Earth's Radiant Energy System (CERES), the model simulation successfully reproduced larger variations of CRESW over the tropical western and central Pacific, Indonesian regions, and the eastern Pacific, as well as large variations of CRELW located mainly within the tropics. The ENSO cycle is found to dominate interannual variations of cloud radiative effects, especially over the tropics. Relative to those during La Niña events, simulated cooling (warming) effects from CRESW (CRELW) during El Niño events are stronger over tropical western and central Pacific, with the largest difference exceeding 40 Wm-2 (30 Wm-2), and weaker effects of 10-30 Wm-2 over Indonesian regions and the subtropical Pacific. Sensitivity tests show that variations of cloud radiative effects are mainly driven by ENSO-induced changes in cloud fraction. However, changes in natural aerosol concentrations, primarily due to changes in wet scavenging and transport processes, also play an important role in modulating the variations of cloud radiative effects. Because of increased (decreased) precipitation in El Niño (La Niña) events, increased (decreased) wet scavenging and transport of natural aerosols offset about 10% of variations of cloud radiative effects averaged over the tropics, whereas the emission changes enhance the variations by 4-6%. Moreover, the variation in medium and high cloud fraction accounts for about 20-50% of the interannual variations of CRESW over the tropics and almost all of the variations of CRELW between 60°S and 60°N. The variation of low cloud fraction plays a dominant role in contributing

  7. Field intercomparison of precipitation samplers for assessing wet deposition of organic contaminants. Final report

    SciTech Connect

    Eisenreich, S.J.; Franz, T.P.; Swanson, M.B.

    1990-03-01

    A field intercomparison of four wet-only precipitation samplers were performed to assess their ability to efficiently collect rain and selected organic contaminants. Samplers are evaluated and compared on the basis of their ability to efficiently collect rainfall, exhibit mechanical reliability, demonstrate adequate operational characteristics and provide precise measures of wet-only inputs. The most significant difference between the four samplers was their mechanical reliability in the field. The samplers performed equally well in assessing organic concentrations in rain. The sampler intercomparison was conducted in part to select the preferred characteristics of a rain sampler that must be deployed in the field unattended for up to two weeks. The MIC sampler, properly maintained, is suitable for such a purpose. Of the two modes of compound isolation tested, the resin adsorbent (XAD-2) exhibited modestly higher concentrations that the solvent MIC but had the disadvantage of ease of sample handling and lower blanks. Both could be operated with proper maintance to provide precise data. The stainless steel and Teflon coated funnel surfaces provided comparable data.

  8. Regional background aerosols over the Balearic Islands over the last 3 years: ground-based concentrations, atmospheric deposition and sources

    NASA Astrophysics Data System (ADS)

    Cerro, Jose Carlos; Pey, Jorge; Bujosa, Carles; Caballero, Sandra; Alastuey, Andres; Sicard, Michael; Artiñano, Begoña; Querol, Xavier

    2013-04-01

    In the context of the ChArMEx (The Chemistry-Aerosol Mediterranean Experiment, https://charmex.lsce.ipsl.fr) initiative, a 3-year study over a regional background environment (Can Llompart, CLP) in Mallorca has been conducted. Ground-based PM mass concentrations, gaseous pollutants and meteorological parameters were continuously registered from 2010 to 2012. Since the beginning of the campaign, PM10 daily samples for chemical determinations were obtained every 4 days, and dry and wet deposition samples were collected every week. Moreover, additional instruments (condensation particle counter, multi-angle absorption photometer, airpointer, sequential high and low volume samplers) were deployed during intensive filed campaigns in 2011 and 2012, as well as the sampling frequency was intensified. In the laboratory, PM samples were analyzed for inorganic compounds, and organic and elemental carbon following different approaches. In addition, n-alkanes, iso-alkanes, antiso-alkanes, levoglucosan, alkanoic acids and cholesterol were determined by GC-MS chromatography in a selection of 30 samples. Mean PM10, PM2.5 and PM1 concentrations in the period 2010-2012 reached 17, 11, and 8 µg/m3 respectively. Mass concentrations displayed marked seasonal trends, with much higher background levels in summer due to stagnant conditions over the western Mediterranean and increased frequency of Saharan dust events. Likewise, diverse-intensity peaks of coarse PM due to African dust inputs were observed along the year. On average, African dust in PM10 accounted for 1.0-1.5 µg/m3. Sporadic pollution events, characterized by most of the particles in the fine mode, were related to the transport of anthropogenic polluted air masses from central and eastern Europe. Wet and dry atmospheric deposition samples are being analyzed to quantify the deposition fluxes for different soluble and insoluble compounds. On average, PM10 composition is made up of organic matter (23%), mineral components (17

  9. Influence of elastase-induced emphysema and the inhalation of an irritant aerosol on deposition and retention of an inhaled insoluble aerosol in Fischer-344 rats

    SciTech Connect

    Damon, E.G.; Mokler, B.V.; Jones, R.K.

    1983-01-01

    The purpose of this study was to assess the effects of elastase-induced pulmonary emphysema and the inhalation of an irritant aerosol (Triton X-100, a nonionic surfactant similar to those used in a number of pressurized consumer products) on pulmonary deposition and retention of an insoluble test aerosol, /sup 59/FE-labeled Fe/sub 2/O/sub 3/. Untreated rats or rats pretreated by intratracheal in stillation with elastase were exposed to an aerosol of /sup 59/Fe-labeled Fe/sub 2/O/sub 3/ either 18 hr or 7 days after exposure to aerosslized Triton X-100 which was administered in doses of 20, 100, or 200 ..mu..g/g of lung. Rats pretreated with elastase had significantly lower pulmonary deposition of /sup 59/Fe than the untreated controls (p < 0.005). Pulmonary deposition of Fe/sub 2/O/sub 3/ was unaffected by pretreatment with Triton X-100. Elastase treatment alone had no effect on retention of Fe/sub 2/O/sub 3/. Triton X-100 administered 18 hr prior to exposure of rats to Fe/sub 2/O/sub 3/ aerosol resulted in dose-related increases in whole-body retention of /sup 59/Fe. When rats were exposed to Triton X-100 7 days before exposure to Fe/sub 2/O/sub 3/, increased retention of /sup 59/Fe was noted only in those treated at the highest Triton X-100 dose level (200 ..mu..g/g). 20 references, 5 tables.

  10. Assessing pesticide wet deposition risk within a small agricultural watershed in the Southeastern Coastal Plain (USA)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pesticide volatilization and deposition with precipitation is widely documented and has been connected to adverse ecological impact. Here we describe a 3-yr study of current use and legacy pesticides in event-based rain samples within a 123-ha agricultural watershed. Crops in farm fields were docum...

  11. Characteristic angles in the wetting of an angular region: deposit growth.

    PubMed

    Popov, Yuri O; Witten, Thomas A

    2003-09-01

    Solids dispersed in a drying drop migrate to the (pinned) contact line. This migration is caused by outward flows driven by the loss of the solvent due to evaporation and by geometrical constraint that the drop maintains an equilibrium surface shape with a fixed boundary. Here, in continuation of our earlier paper, we theoretically investigate the evaporation rate, the flow field, and the rate of growth of the deposit patterns in a drop over an angular sector on a plane substrate. Asymptotic power laws near the vertex (as distance to the vertex goes to zero) are obtained. A hydrodynamic model of fluid flow near the singularity of the vertex is developed and the velocity field is obtained. The rate of the deposit growth near the contact line is found in two time regimes. The deposited mass falls off as a weak power gamma of distance close to the vertex and as a stronger power beta of distance further from the vertex. The power gamma depends only slightly on the opening angle alpha and stays roughly between -1/3 and 0. The power beta varies from -1 to 0 as the opening angle increases from 0 degrees to 180 degrees. At a given distance from the vertex, the deposited mass grows faster and faster with time, with the greatest increase in the growth rate occurring at the early stages of the drying process.

  12. Estimation of mercury wet deposition in the tributary sub-basins of the Negro river (Amazon-Brazil) using RS/GIS tools

    NASA Astrophysics Data System (ADS)

    Jardim, W. F.; Silvério da Silva, G.

    2003-05-01

    Recent studies have shown high concentrations of Hg in fish, soil, lakes and rivers of the Negro river basin. These concentrations were surprisingly high when considering the scarcity of anthropogenic point sources in the region (Fadini and Jardim, 2001). In order to investigate the role of wet deposition in the mercury biogeochemistry cycle in this basin, Hg deposition was estimated for 18 tributary sub-basins of the Negro river, covering an area of nearly 700,000 km2. Mercury wet deposition estimate was done by combining analytical data obtained from total Hg measurements in bulk precipitation (8 measurements between 1997 and 2002), Remote Sensoring (RS) and GIS (Geographie Information System) tools, with the help of orbital images from the JERS-1 SAR project (Global Rain Forest Mapping Project, South America-Amazon Basin), Amazon rainfall map (Sombroek, 2001) and SPRING (Geographie information of processing system) from INPE (Brazilian National Institute of Space Research). For each sub-basin, Hg wet deposition flux (ton km^{-2} yr^{-1}) and the annual amount of Hg (ton yr^{-1}) deposited on the area were estimated. The result allowed a clear picture of each sub-basins, by looking for a relation between the wet deposition, the drainage characteristics of each sub-basin and the Hg concentration in the water column.

  13. Fabrication of a hollow needle structure by dicing, wet etching and metal deposition

    NASA Astrophysics Data System (ADS)

    Shikida, Mitsuhiro; Hasada, Takehiko; Sato, Kazuo

    2006-10-01

    We previously proposed a novel fabrication process, which combined mechanical dicing and anisotropic wet etching, to reduce the cost of micro-electro-mechanical system devices, and fabricated various solid-type microneedle structures using this process for trans-dermal drug delivery systems. The current research involved us enhancing our previous processes by applying metal plating and using a minimum number of photolithography steps, and we fabricated a hollow-type micro-needle structure, in which a flow channel was formed at the center of the needle projection, for supplying medical solutions from the area behind the needle. We fabricated two different shaped needle structures, pyramidal and flattened needles. The height and pitch of both needle types were 120-250 µm and 230-280 µm, respectively. The developed process is useful for producing disposable microneedles for bio-medical applications.

  14. ¹¹¹Indium-labeled ultrafine carbon particles; a novel aerosol for pulmonary deposition and retention studies.

    PubMed

    Sanchez-Crespo, Alejandro; Klepczynska-Nyström, Anna; Lundin, Anders; Larsson, Britt Marie; Svartengren, Magnus

    2011-02-01

    Continuous environmental or occupational exposure to airborne particulate pollution is believed to be a major hazard for human health. A technique to characterize their deposition and clearance from the lungs is fundamental to understand the underlying mechanisms behind their negative health effects. In this work, we describe a method for production and follow up of ultrafine carbon particles labeled with radioactive ¹¹¹Indium (¹¹¹In). The physicochemical and biological properties of the aerosol are described in terms of particle size and concentration, agglomeration rate, chemical bonding stability, and human lung deposition and retention. Preliminary in vivo data from a healthy human pilot exposure and 1-week follow up of the aerosol is presented. More than 98% of the generated aerosol was labeled with Indium and with particle sizes log normally distributed around 79  nm count median diameter. The aerosol showed good generation reproducibility and chemical stability, about 5% leaching 7 days after generation. During human inhalation, the particles were deposited in the alveolar space, with no central airways involvement. Seven days after exposure, the cumulative activity retention was 95.3%. Activity leaching tests from blood and urine samples confirmed that the observed clearance was explained by unbound activity, suggesting that there was no significant elimination of ultrafine particles. Compared to previously presented methods based on Technegas, ¹¹¹In-labelled ultrafine carbon particles allow for extended follow-up assessments of particulate pollution retention in healthy and diseased lungs.

  15. Spatial patterns and temporal trends in mercury concentrations, precipitation depths, and mercury wet deposition in the North American Great Lakes region, 2002-2008

    USGS Publications Warehouse

    Risch, Martin R.; Gay, David A.; Fowler, Kathleen K.; Keeler, Gerard J.; Backus, Sean M.; Blanchard, Pierrette; Barres, James A.; Dvonch, J. Timothy

    2012-01-01

    Annual and weekly mercury (Hg) concentrations, precipitation depths, and Hg wet deposition in the Great Lakes region were analyzed by using data from 5 monitoring networks in the USA and Canada for a 2002-2008 study period. High-resolution maps of calculated annual data, 7-year mean data, and net interannual change for the study period were prepared to assess spatial patterns. Areas with 7-year mean annual Hg concentrations higher than the 12 ng per liter water-quality criterion were mapped in 4 states. Temporal trends in measured weekly data were determined statistically. Monitoring sites with significant 7-year trends in weekly Hg wet deposition were spatially separated and were not sites with trends in weekly Hg concentration. During 2002-2008, Hg wet deposition was found to be unchanged in the Great Lakes region and its subregions. Any small decreases in Hg concentration apparently were offset by increases in precipitation.

  16. High-performance energy harvester fabricated with aerosol deposited PMN-PT material

    NASA Astrophysics Data System (ADS)

    Chen, C. T.; Lin, S. C.; Lin, T. K.; Wu, W. J.

    2016-11-01

    This paper reports a high-performance piezoelectric energy harvester (EH) fabricated with xPb(Mg1/3Nb2/3)-(l-x)PbTiO3 (PMN-PT) by aerosol deposition method. The result indicates that PMN-PT based EH owns 1.8 times output power which is higher than traditional PbZrxTi1- xO3 (PZT) based EH. In order to compare the output performance of EH fabricated with PMN- PT compared with PZT, the similar thickness of PMN-PT and PZT thin film is deposited on stainless steel subtracted. The experimental results show that PZT-based EH had a maximum output power of 4.65 μW with 1.11 Vp-p output voltage excited at 94.4 Hz under 0.5g base excitation, while the PMN-PT based device has a maximum output power of 8.42 μW with 1.49 Vp-p output voltage at a vibration frequency of 94.8 Hz and the same base excitation level. The volumetric power density was 82.95 μW/mm3 and 48.05 μW/mm3 for the device based on PMN- PT and PZT materials, respectively. All the results demonstrate that PMN-PT has better output performance than PZT.

  17. Microstructure and Magnetic Properties of the Aerosol-Deposited Sm-Fe-N Thick Films

    NASA Astrophysics Data System (ADS)

    Maki, Tomohito; Sugimoto, Satoshi; Kagotani, Toshio; Inomata, Koichiro; Akedo, Jun

    In this study, the relationship among magnetic properties, Aerosol Deposition (AD) conditions and microstructures in Sm-Fe-N AD films were investigated. The maximum thickness of 145 μm was obtained in the AD conditions of gas flow rate (gfr) = 6 L/min for 10 min. The density of Sm-Fe-N films were in the range of 5.43 - 6.24 g/cm3, which were 71 - 81 % of the X-ray density of the Sm2Fe17N3 compound reported (7.67 g/cm3). The Sm-Fe-N AD films showed remanence in the range of 0.38 - 0.42 T, which were 61 - 68 % of that of Sm-Fe-N host powder (0.62 T). The coercivities increased from 1.16 to 1.74 - 1.79 T after the deposition because the grain size decreased from 1.94 to 0.32 μm.

  18. Mass Spectrometric Analysis of Pristine Aerosol Particles During the wet Season of Amazonia - Detection of Primary Biological Particles?

    NASA Astrophysics Data System (ADS)

    Schneider, J.; Zorn, S. R.; Freutel, F.; Borrmann, S.; Chen, Q.; Farmer, D. K.; Jimenez, J. L.; Flores, M.; Roldin, P.; Artaxo, P.; Martin, S. T.

    2008-12-01

    The contribution of primary biological aerosol (POA) particles to the natural organic aerosol is a subject of current research. Estimations of the POA contribution to the total aerosol particle concentration range between 25 and 80%, depending on location and season. Especially in the tropical rain forest it is expected that POA is a major source of supermicron, possibly also of submicron particles. During AMAZE (Amazonian Aerosol CharacteriZation Experiment), a field project near Manaus, Brazil, in February/March 2008, an Aerodyne ToF-AMS was equipped with a high pressure aerodynamic lens. This high pressure lens (operating pressure 14.6 torr) is designed with the objective to extend the detectable size range of the AMS into the supermicron size range where primary biological particles are expected. Size distribution measured by the AMS were compared with size distribution from an optical particle counter and indicate that the high pressure lens has a 50% cut-off at a vacuum aerodynamic diameter of about 1 μm, but still has significant transmission up to a vacuum aerodynamic diameter of about 2 μm, thus extending the detectable size range of the AMS into the coarse mode. The measuring instruments were situated in a container at ground level. The aerosol was sampled through a 40 m vertical, laminar inlet, which was heated and dried to maintain a relative humidity between 30 and 40%. The inlet was equipped with a 7 μm cut-off cyclone. Size distributions recorded with an optical particle counter parallel to the AMS show that the inlet transmitted aerosol particles up to an optically detected diameter of 10 μm. POA particles like plant fragments, pollen, spores, fungi, viruses etc. contain chemical compounds as proteins, sugars, amino acids, chlorophyll, and cellular material as cellulose. Laboratory experiments have been performed in order to identify typical mass spectral patterns of these compounds. These laboratory data were compared to size resolved particle

  19. Nitrogen chemistry in surface waters and wet deposition at high altitude in the Sagarmatha (Mt Everest) National Park.

    NASA Astrophysics Data System (ADS)

    Balestrini, R.; Polesello, S.; Rusconi, M.

    2012-04-01

    The knowledge of the nitrogen cycle is mainly based on studies conducted in relatively human-altered zones located in the north-western hemisphere. Therefore it is of great interest to identify the limits of natural variations of nitrogen in ecosystems that have not experienced the nitrogen pollution, and have undergone minor alterations from human activities. Among the alpine environments of the world, the region of Mount Everest, is a unique ecosystem with a degree of biodiversity among the highest existing, but characterized by a recognized fragility and low resilience. The extreme climate, the slow growing seasons and the thin soils make this ecosystem very sensitive to any environmental change. A yearly sampling campaign was conducted in the Sagarmatha National Park (Nepal) during the monsoon season in 2008 to collect surface water samples at high elevation from 4300 to 5500 m asl. In addition during 2007 and 2008 the sampling of wet deposition was carried on at 5050 m asl at the Nepal Climate Observatory - Pyramid ABC site. The nitrate concentration in the running waters fell in the lower range of the values reported for comparable environments in Europe. As well, the wet deposition load of nitrogen was remarkable lower than those observed in high elevation areas in Europe and North America. A comparison among running waters, precipitations and small lakes, located in the same area, revealed significant higher nitrate concentrations in running waters compared to the other two matrixes. Conversely, ammonia level resulted higher in the rain compared to surface waters. The spatial and temporal variation of the chemical species in running waters were analyzed taking in account the use of soil in the basins and the hydrological regime.

  20. Trace elements and rare earth elements in wet deposition of Lijiang, Mt. Yulong region, southeastern edge of the Tibetan Plateau.

    PubMed

    Guo, Junming; Kang, Shichang; Huang, Jie; Sillanpää, Mika; Niu, Hewen; Sun, Xuejun; He, Yuanqing; Wang, Shijing; Tripathee, Lekhendra

    2017-02-01

    In order to investigate the compositions and wet deposition fluxes of trace elements and rare earth elements (REEs) in the precipitation of the southeastern edge of the Tibetan Plateau, 38 precipitation samples were collected from March to August in 2012 in an urban site of Lijiang city in the Mt. Yulong region. The concentrations of most trace elements and REEs were higher during the non-monsoon season than during the monsoon season, indicating that the lower concentrations of trace elements and REEs observed during monsoon had been influenced by the dilution effect of increased precipitation. The concentrations of trace elements in the precipitation of Lijiang city were slightly higher than those observed in remote sites of the Tibetan Plateau but much lower than those observed in the metropolises of China, indicating that the atmospheric environment of Lijiang city was less influenced by anthropogenic emissions, and, as a consequence, the air quality was still relatively good. However, the results of enrichment factor and principal component analysis revealed that some anthropogenic activities (e.g., the increasing traffic emissions from the rapid development of tourism) were most likely important contributors to trace elements, while the regional/local crustal sources rather than anthropogenic activities were the predominant contributors to the REEs in the wet deposition of Lijiang city. Our study was relevant not only for assessing the current status of the atmospheric environment in the Mt. Yulong region, but also for specific management actions to be implemented for the control of atmospheric inputs and the health of the environment for the future.

  1. Validation of radiolabeling of drug formulations for aerosol deposition assessment of orally inhaled products.

    PubMed

    Devadason, Sunalene G; Chan, Hak-Kim; Haeussermann, Sabine; Kietzig, Claudius; Kuehl, Philip J; Newman, Stephen; Sommerer, Knut; Taylor, Glyn

    2012-12-01

    Radiolabeling of inhaler formulations for imaging studies is an indirect method of determining lung deposition and regional distribution of drug in human subjects. Hence, ensuring that the radiotracer and drug exhibit similar aerodynamic characteristics when aerosolized, and that addition of the radiotracer has not significantly altered the characteristics of the formulation, are critical steps in the development of a radiolabeling method. The validation phase should occur during development of the radiolabeling method, prior to commencement of in vivo studies. The validation process involves characterization of the aerodynamic particle size distribution (APSD) of drug in the reference formulation, and of both drug and radiotracer in the radiolabeled formulation, using multistage cascade impaction. We propose the adoption of acceptance criteria similar to those recommended by the EMA and ISAM/IPAC-RS for determination of therapeutic equivalence of orally inhaled products: (a) if only total lung deposition is being quantified, the fine particle fraction ratio of both radiolabeled drug and radiotracer to that of the reference drug should fall between 0.85 and 1.18, and (b) if regional lung deposition (e.g., outer and inner lung regions) is to be quantified, the ratio of both radiolabeled drug and radiotracer to reference drug on each impactor stage or group of stages should fall between 0.85 and 1.18. If impactor stages are grouped together, at least four separate groups should be provided. In addition, while conducting in vivo studies, measurement of the APSD of the inhaler used on each study day is recommended to check its suitability for use in man.

  2. Fate of inhaled monoclonal antibodies after the deposition of aerosolized particles in the respiratory system.

    PubMed

    Guilleminault, L; Azzopardi, N; Arnoult, C; Sobilo, J; Hervé, V; Montharu, J; Guillon, A; Andres, C; Herault, O; Le Pape, A; Diot, P; Lemarié, E; Paintaud, G; Gouilleux-Gruart, V; Heuzé-Vourc'h, N

    2014-12-28

    Monoclonal antibodies (mAbs) are usually delivered systemically, but only a small proportion of the drug reaches the lung after intravenous injection. The inhalation route is an attractive alternative for the local delivery of mAbs to treat lung diseases, potentially improving tissue concentration and exposure to the drug while limiting passage into the bloodstream and adverse effects. Several studies have shown that the delivery of mAbs or mAb-derived biopharmaceuticals via the airways is feasible and efficient, but little is known about the fate of inhaled mAbs after the deposition of aerosolized particles in the respiratory system. We used cetuximab, an anti-EGFR antibody, as our study model and showed that, after its delivery via the airways, this mAb accumulated rapidly in normal and cancerous tissues in the lung, at concentrations twice those achieved after intravenous delivery, for early time points. The spatial distribution of cetuximab within the tumor was heterogeneous, as reported after i.v. injection. Pharmacokinetic (PK) analyses were carried out in both mice and macaques and showed aerosolized cetuximab bioavailability to be lower and elimination times shorter in macaques than in mice. Using transgenic mice, we showed that FcRn, a key receptor involved in mAb distribution and PK, was likely to make a greater contribution to cetuximab recycling than to the transcytosis of this mAb in the airways. Our results indicate that the inhalation route is potentially useful for the treatment of both acute and chronic lung diseases, to boost and ensure the sustained accumulation of mAbs within the lungs, while limiting their passage into the bloodstream.

  3. Temporal, Directional, and Spatial Variability of Wet Deposition in the Northeastern United States.

    DTIC Science & Technology

    1981-04-23

    relation between acids and bases to interpret the amount of acid found in precipitation and predict future depositions of acid by precipitation. Munn...be 6.5 to 6.6, with extreme variations ranging from 5.8 to 7.3. He also found that the pH 21 decreased as the alkaline CaCO3 -bearing particulates were...the temporal and spatial scale. Spatial variability Is difficult to interpret since the degree of coherency between stations is not usually proven

  4. The effect of large anthropogenic particulate emissions on atmospheric aerosols, deposition and bioindicators in the eastern Gulf of Finland region.

    PubMed

    Jalkanen, L; Mäkinen, A; Häsänen, E; Juhanoja, J

    2000-10-30

    The effect of the emissions from large oil shale fuelled power plants and a cement factory in Estonia on the elemental concentration of atmospheric aerosols, deposition, elemental composition of mosses and ecological effects on mosses, lichens and pine trees in the eastern Gulf of Finland region has been studied. In addition to chemical analysis, fly ash, moss and aerosol samples were analysed by a scanning electron microscope with an energy dispersive X-ray spectrometer (SEM/EDS). The massive particulate calcium emissions, approximately 60 kton/year (1992), is clearly observed in the aerosols, deposition and mosses. The calcium deposition is largest next to the Russian border downwind from the power plants and in south-eastern part of Finland. This deposition has decreased due to the application of dust removal systems at the particulate emission sources. At the Virolahti EMEP station approximately 140 km north from the emission sources, elevated elemental atmospheric aerosol concentrations are observed for Al, Ca, Fe, K and Si and during episodes many trace elements, such as As, Br, Mo, Ni, Pb and V. The acidification of the soil is negligible because of the high content of basic cations in the deposition. Visible symptoms on pine trees are negligible. However, in moss samples close to the power plants, up to 25% of the leaf surface was covered by particles. Many epiphytic lichen species do not tolerate basic stemflow and on the other hand most species are also very sensitive for the SO2 content in air. Consequently a large lichen desert is found in an area of 2500 km2 in the vicinity of the power plants with only one out of the investigated 12 species growing.

  5. Decadal trend of black carbon and refractory carbonaceous aerosol in the western rim of the North Pacific Ocean: atmospheric concentration and the retrieved record of deposition flux

    NASA Astrophysics Data System (ADS)

    Kaneyasu, Naoki; Yamaguchi, Takashi; Noguchi, Izumi; Akiyama, Masayuki; Matsumoto, Kiyoshi

    2013-04-01

    The long-term trend of light absorbing carbonaceous aerosols (or black carbon: BC) or refractory carbonaceous aerosol (or elemental carbon: EC) concentration is reported at European background sites such as Mace Head, and that of aerosol absorption coefficient are monitored in many GAW sites. On the contrary, such long-term data are relatively scarce at around the western part of the North Pacific Ocean. Thus, to understand the long-term variation of in the area, BC in fine aerosol fraction has been measured at Chichi-jima Islands, Japan. Chichi-jima Island is located 1000 km south of the Japanese mainland, and 1800 km west of the coast line of the Asian continent. BC has been measured with an Aethalometer (Magee, AE-16 and AE-30) since December, 1998 with 1 hr time resolution. Mass flowmeter embedded inside the Aethalometer is calibrated with a rotational dry gas-meter once a year. Monthly averaged BC concentration shows an obvious seasonal variation, i.e. high concentration during late autumn-winter-spring period resulting from the transport from East Asia, with maximum daily concentration above 500 ng m-3. In summer, daily concentration was usually less than 20 ng m-3, due to the clean background airmass originating from the North Pacific Anticyclone. Decadal trend of the annual averaged BC concentration showed a increasing trend from 2000 to 2007 and started to decrease after 2008, which roughly coincides with the reported emission trend of SO2 in China (Lu et al., 2010). In addition, total (i.e., wet + dry) deposition record of refractory carbon at two sites in the northern Japan (Rishiri Island: a remote island site, and Sapporo City: an urban site) are retrieved. At these sites, the local government have been measuring the chemical components in precipitation water collected by deposition gauges. In the deposition gauge, a membrane filter made of cellulose-acetate is fixed at the bottom of the funnel to remove water-insoluble particles from the precipitated

  6. Wet and dry deposition of 129I in Seville (Spain) measured by accelerator mass spectrometry.

    PubMed

    López-Gutiérrez, J M; García-León, M; Schnabel, C; Suter, M; Synal, H A; Szidat, S

    2001-01-01

    Iodine-129 (T1/2 = 1.57 x 10(7) yr) concentrations have been determined by accelerator mass spectrometry in rainwater samples taken at Seville (southwestern Spain) in 1996 and 1997. This technique allows a reduction in the detection limits for this radionuclide in comparison to radiometric counting and other mass spectrometric methods such as ICP-MS. Typical 129I concentrations range from 4.7 x 10(7) 129I atoms/l (19.2%) to 4.97 x 10(9) 129I atoms/l (5.9%), while 129I depositions are normally in the order of 10(8)-10(10) atoms/m2d. These values agree well with other results obtained for recent rainwater samples collected in Europe. Apart from these, the relationship between 129I deposition and some atmospheric factors has been analyzed, showing the importance of the precipitation rate and the concentration of suspended matter in it.

  7. GENERATION, TRANSPORT AND DEPOSITION OF TUNGSTEN-OXIDE AEROSOLS AT 1000 C IN FLOWING AIR-STEAM MIXTURES.

    SciTech Connect

    GREENE,G.A.; FINFROCK,C.C.

    2001-10-01

    Experiments were conducted to measure the rates of oxidation and vaporization of pure tungsten rods in flowing air, steam and air-steam mixtures in laminar flow. Also measured were the downstream transport of tungsten-oxide condensation aerosols and their region of deposition, including plateout in the superheated flow tube, rainout in the condenser and ambient discharge which was collected on an array of sub-micron aerosol filters. The nominal conditions of the tests, with the exception of the first two tests, were tungsten temperatures of 1000 C, gas mixture temperatures of 200 C and wall temperatures of 150 C to 200 C. It was observed that the tungsten oxidation rates were greatest in all air and least in all steam, generally decreasing non-linearly with increasing steam mole fraction. The tungsten oxidation rates in all air were more than five times greater than the tungsten oxidation rates in all steam. The tungsten vaporization rate was zero in all air and increased with increasing steam mole fraction. The vaporization rate became maximum at a steam mole fraction of 0.85 and decreased thereafter as the steam mole fraction was increased to unity. The tungsten-oxide was transported downstream as condensation aerosols, initially flowing upwards from the tungsten rod through an 18-inch long, one-inch diameter quartz tube, around a 3.5-inch radius, 90{sup o} bend and laterally through a 24-inch horizontal run. The entire length of the quartz glass flow path was heated by electrical resistance clamshell heaters whose temperatures were individually controlled and measured. The tungsten-oxide plateout in the quartz tube was collected, nearly all of which was deposited at the end of the heated zone near the entrance to the condenser which was cold. The tungsten-oxide which rained out in the condenser as the steam condensed was collected with the condensate and weighed after being dried. The aerosol smoke which escaped the condenser was collected on the sub

  8. Wet deposition and soil content of Beryllium - 7 in a micro-watershed of Minas Gerais (Brazil).

    PubMed

    Esquivel L, Alexander D; Moreira, Rubens M; Monteiro, Roberto Pellacani G; Dos Santos, Anômora A Rochido; Juri Ayub, Jimena; Valladares, Diego L

    2017-04-01

    Beryllium-7 ((7)Be) is a natural radionuclide of cosmogenic origin, normally used as a tracer for several environmental processes; such as soil redistribution, sediment source discrimination, atmospheric mass transport, and trace metal scavenging from the atmosphere. In this research the content of (7)Be in soil, its seasonal variation throughout the year and its relationship with the rainfall regime in the Mato Frio creek micro-watershed was investigated, to assess its potential use in estimating soil erosion. The (7)Be content in soil shows a marked variation throughout the year. Minimum (7)Be values were observed in the dry season (from April to September) and were between 7 and 14 times higher in the rainy season (from October to March). The seasonal oscillations in (7)Be soil content could be explained by the asymmetric rainfall regime. A highly linear relationship between rainfall amount and (7)Be deposition was observed in rain water. A good agreement between (7)Be soil content and (7)Be atmospheric deposition was noticed, mainly in wet months. (7)Be penetration in soil reaches a 5 cm depth, this could be explained by the soil type in the region. The soils are Acrisol type, characterized by low pH values and clay illuviation in deeper layers of the soil. In some regions of Brazil special attention should be paid if this radionuclide will be used as soil erosion tracer, taking into account the soil origin and its particular properties.

  9. Enhancement of the deposition of ultrafine secondary organic aerosols by the negative air ion and the effect of relative humidity.

    PubMed

    Yu, Kuo-Pin

    2012-11-01

    Deposition is an important process for the removal of aerosol particles. Negative air ion (NAI) generators can charge the ultrafine airborne particles and enhance their deposition rate. However, many NAI generators may also emit ozone and increase the concentration of particles in the presence of biogenic volatile organic compounds owing to the secondary organic aerosol (SOA) production. To validate the effectiveness of NAI generator the authors investigated the enhancement effect of an NAI generator on the deposition of the ultrafine SOAs generated from the ozonolysis of d-limonene in a test chamber under controlled ventilation rate and relative humidity (RH). The experimental results demonstrated that compared with other effects, including the gravity, particle eddy diffusion, and the Brownian diffusion, the effect of NAIs is the most dominate one on the deposition of SOA particles onto the wall surface in the near-wall region (<1 cm away from the wall). According to these experiments, the tested NAI generator could efficiently enhance the deposition rate by an enhancement factor ranging from 8.17 +/- 0.38 to 25.3 +/- 1.1, with a low ozone production rate. This NAI generator had better performance on the deposition of the SOAs with smaller particle sizes and it performed even better under higher RH. The enhancement effect of the NAI generator was related to its high NAI production and electric field strength.

  10. Pulmonary deposition of aerosolized Bacillus atrophaeus in a Swine model due to exposure from a simulated anthrax letter incident.

    PubMed

    Duncan, E J Scott; Kournikakis, Bill; Ho, Jim; Hill, Ira

    2009-02-01

    Dry anthrax spore powder is readily disseminated as an aerosol and it is possible that passive dispersion when opening a letter containing anthrax spores may result in lethal doses to humans. The specific aim of this study was to quantify the respirable aerosol hazard associated with opening an envelope/letter contaminated with a dry spore powder of the biological pathogen anthrax in a typical office environment. An envelope containing a letter contaminated with 1.0 g of dry Bacillus atrophaeus (BG) spores (pathogen simulant) was opened in the presence of an unrestrained swine model. Aerosolized spores were detected in the room in seconds and peak concentrations occurred by three minutes. The swine, located approximately 1.5 m from the source, was exposed to the aerosol for 28 min following the letter opening event and then moved to a clean room for 30 min. A necropsy was completed to determine the extent of in vivo spore deposition in the lungs. The median number of viable colony forming units (CFU) measured in the combined right and left lung was 21,200: the average mass of both lungs was 283 g. In excess of 100 CFU per gram of lung tissue was found at sites within the anterior, intermediate and posterior lobes. The results of this study confirmed that opening an envelope containing spores generated an aerosol spanning the respirable particle size range of 1-10 microm, and that normal respiration of swine led to spore deposition throughout the lungs. The observed deposition of spores in the lungs of the swine is within the LD(50) range of 2,500-55,000 estimated for humans for inhaled anthrax. Thus, there would appear to be a significant health risk to those individuals exposed to anthrax spores when opening a contaminated envelope.

  11. Characteristics of mineral aerosol deposited on the glaciers of Mt. Elbrus, Caucasus, Russia.

    NASA Astrophysics Data System (ADS)

    Kutuzov, Stanislav; Shahgedanova, Maria; Mikhalenko, Vladimir; Ginot, Patrick; Lavrentiev, Ivan; Popov, Gregory

    2014-05-01

    Records of mineral aerosol (desert dust) stored in glaciers provide data on frequency and intensity of deposition events, source regions and atmospheric pathways of mineral dust. We present and discuss a chronology of dust deposition events recorded in the shallow firn and ice cores extracted on the Western Plateau, Mt. Elbrus (5150 m a.s.l.), Caucasus Mountains, Russia and covering the period of 2009-2013. Particle size distribution and chemical analysis (major ions, trace elements) were peformed using Coulter Counter Multisizer III, Abacus particle counter, IC and ICPMS analysis. Sampling was performed using continuous flow analysis (CFA) system. Annual average dust flux (264 μg/cm2 a-1) and average mass concentration (1.7 mg/kg) over the period 2007-2013 were calculated for the first time for this region. A combination of satellite imagery (MSG SEVIRI), trajectory models (FLEXTA, HYSPLIT) and meteorological data were used to accurately date each of the dust layers observed in shallow cores and investigate provenance of the dust and its pathways. Desert dust originating from the Middle East and Sahara was deposited on the Caucasus glaciers 3-6 times a year. Although less frequent, Saharan events are characterized by considerably higher dust loads than the more frequent Middle Eastern events. The mass median diameter of dust particles ranged between 2 and 9 μm. The deposition of dust resulted in elevated concentrations of most ions, especially Ca2+, Mg2+, K+, and sulphates. Dust originated from or passing over the Middle East was characterised by the elevated concentrations of nitrates and ammonia. This may be related to dust emissions from agricultural fields which, if abandoned due to droughts, become important sources of dust. By contrast, samples of the Saharan dust originated from natural sources showed lower concentrations of ammonium. The mean values of crustal enrichment factors for the measured trace elements including metals were calculated. Overall

  12. Inertia in an ombrotrophic bog ecosystem in response to 9 years' realistic perturbation by wet deposition of nitrogen, separated by form.

    PubMed

    Sheppard, Lucy J; Leith, Ian D; Mizunuma, Toshie; Leeson, Sarah; Kivimaki, Sanna; Neil Cape, J; van Dijk, Netty; Leaver, David; Sutton, Mark A; Fowler, David; Van den Berg, Leon J L; Crossley, Alan; Field, Chris; Smart, Simon

    2014-02-01

    Wet deposition of nitrogen (N) occurs in oxidized (nitrate) and reduced (ammonium) forms. Whether one form drives vegetation change more than the other is widely debated, as field evidence has been lacking. We are manipulating N form in wet deposition to an ombrotrophic bog, Whim (Scottish Borders), and here report nine years of results. Ammonium and nitrate were provided in rainwater spray as NH4 Cl or NaNO3 at 8, 24 or 56 kg N ha(-1)  yr(-1) , plus a rainwater only control, via an automated system coupled to site meteorology. Detrimental N effects were observed in sensitive nonvascular plant species, with higher cumulative N loads leading to more damage at lower annual doses. Cover responses to N addition, both in relation to form and dose, were species specific and mostly dependent on N dose. Some species were generally indifferent to N form and dose, while others were dose sensitive. Calluna vulgaris showed a preference for higher N doses as ammonium N and Hypnum jutlandicum for nitrate N. However, after 9 years, the magnitude of change from wet deposited N on overall species cover is small, indicating only a slow decline in key species. Nitrogen treatment effects on soil N availability were likewise small and rarely correlated with species cover. Ammonium caused most N accumulation and damage to sensitive species at lower N loads, but toxic effects also occurred with nitrate. However, because different species respond differently to N form, setting of ecosystem level critical loads by N form is challenging. We recommend implementing the lowest value of the critical load range where communities include sensitive nonvascular plants and where ammonium dominates wet deposition chemistry. In the context of parallel assessment at the same site, N treatments for wet deposition showed overall much smaller effects than corresponding inputs of dry deposition as ammonia.

  13. Cloud condensation nucleus activity comparison of dry- and wet-generated mineral dust aerosol: the significance of soluble material

    NASA Astrophysics Data System (ADS)

    Garimella, S.; Huang, Y.-w.; Seewald, J. S.; Cziczo, D. J.

    2013-11-01

    This study examines the interaction of clay mineral particles and water vapor to determine the conditions required for cloud droplet formation. Droplet formation conditions are investigated for three clay minerals: illite, sodium-rich montmorillonite, and Arizona Test Dust. Using wet and dry particle generation coupled to a differential mobility analyzer (DMA) and cloud condensation nuclei counter, the critical activation of the clay mineral particles as cloud condensation nuclei is characterized. Electron microscopy (EM) is used to determine non-sphericity in particle shape. EM is also used to determine particle surface area and account for transmission of multiply charged particles by the DMA. Single particle mass spectrometry and ion chromatography are used to investigate soluble material in wet-generated samples and demonstrate that wet and dry generation yield compositionally different particles. Activation results are analyzed in the context of both κ-Köhler theory and Frenkel, Halsey, and Hill (FHH) adsorption activation theory. This study has two main results: (1) κ-Köhler is a suitable framework, less complex than FHH theory, to describe clay mineral nucleation activity despite apparent differences in κ with respect to size. For dry-generated particles the size dependence is likely an artifact of the shape of the size distribution: there is a sharp drop-off in particle concentration at ~300 nm, and a large fraction of particles classified with a mobility diameter less than ~300 nm are actually multiply charged, resulting in a much lower critical supersaturation for droplet activation than expected. For wet-generated particles, deviation from κ-Köhler theory is likely a result of the dissolution and redistribution of soluble material. (2) Wet-generation is found to be unsuitable for simulating the lofting of fresh dry dust because it changes the size-dependent critical supersaturations by fractionating and re-partitioning soluble material.

  14. Determinants of aerosol lung-deposited surface area variation in an urban environment.

    PubMed

    Reche, Cristina; Viana, Mar; Brines, Mariola; Pérez, Noemí; Beddows, David; Alastuey, Andrés; Querol, Xavier

    2015-06-01

    Ultrafine particles are characterized by a high surface area per mass. Particle surface has been reported to play a significant role in determining the toxicological activity of ultrafine particles. In light of this potential role, the time variation of lung deposited surface area (LDSA) concentrations in the alveolar region was studied at the urban background environment of Barcelona (Spain), aiming to asses which processes and sources govern this parameter. Simultaneous data on Black Carbon (BC), total particle number (N) and particle number size distribution were correlated with LDSA. Average LDSA concentrations in Barcelona were 37 ± 26 μm(2)cm(-3), levels which seem to be characteristic for urban environments under traffic influence across Europe. Results confirm the comparability between LDSA data provided by the online monitor and those calculated based on particle size distributions (by SMPS), and reveal that LDSA concentrations are mainly influenced by particles in the size range 50-200 nm. A set of representative daily cycles for LDSA concentrations was obtained by means of a k-means cluster technique. The contribution of traffic emissions to daily patterns was evidenced in all the clusters, but was quantitatively different. Traffic events under stable atmospheric conditions increased mean hourly background LDSA concentrations up to 6 times, attaining levels higher than 200 μm(2)cm(-3). However, under warm and relatively clean atmospheric conditions, the traffic rush hour contribution to the daily LDSA mean appeared to be lower and the contribution of new urban particle formation events (by photochemically induced nucleation) was detected. These nucleation events were calculated to increase average background LDSA concentrations by 15-35% (maximum LDSA levels=45-50 μm(2)cm(-3)). Thereby, it may be concluded that in the urban background of Barcelona road traffic is the main source increasing the aerosol surface area which can deposit on critical

  15. Effect of InspirEase on the deposition of metered-dose aerosols in the human respiratory tract

    SciTech Connect

    Newman, S.P.; Woodman, G.; Clarke, S.W.; Sackner, M.A.

    1986-04-01

    A radiotracer technique has been used to assess the effects of a 700-ml collapsible holding chamber (InspirEase, Key Pharmaceuticals Inc.) on the deposition of metered-dose aerosols in ten patients with obstructive airways disease (mean forced expiratory volume in one second (FEV1), 64.5 percent of predicted). Patterns of deposition obtained by patients' usual techniques with the metered-dose inhaler (MDI) were compared with those by correct MDI technique (actuation coordinated with slow deep inhalation and followed by ten seconds of breath-holding) and with those by InspirEase. Deposition of aerosol was assessed by placing Teflon particles labelled with 99mTc inside placebo canisters, and inhaling maneuvers were monitored by respiratory inductive plethysmography (Respitrace). Nine of the ten patients had imperfect technique with the MDI, the most prevalent errors being rapid inhalation and failure to hold their breath adequately. With patients' usual MDI techniques, 6.5 +/- 1.2 percent (mean +/- SE) of the dose reached the lungs. This was increased to 11.2 +/- 1.3 percent (p less than 0.02) with correct technique and increased further to 14.8 +/- 1.4 percent (p less than 0.05) with InspirEase. Oropharyngeal deposition exceeded 80 percent of the dose for the MDI alone but was only 9.5 +/- 0.9 percent with InspirEase (p less than 0.01); 59.2 +/- 2.1 percent of the dose was retained within InspirEase itself. It is concluded that InspirEase gives whole lung deposition of metered-dose aerosols greater than that from a correctly used MDI, while oropharyngeal deposition is reduced approximately nine times.

  16. A Multi-Resolution Assessment of the Community Multiscale Air Quality (CMAQ) Model v4.7 Wet Deposition Estimates for 2002 - 2006

    EPA Science Inventory

    This paper examines the operational performance of the Community Multiscale Air Quality (CMAQ) model simulations for 2002 - 2006 using both 36-km and 12-km horizontal grid spacing, with a primary focus on the performance of the CMAQ model in predicting wet deposition of sulfate (...

  17. Temporal trajectories of wet deposition across hydro-climatic regimes: Role of urbanization and regulations at U.S. and East Asia sites

    NASA Astrophysics Data System (ADS)

    Park, Jeryang; Gall, Heather E.; Niyogi, Dev; Rao, P. Suresh C.

    2013-05-01

    Dominant global patterns of urbanization and industrialization contribute to large-scale modification of the drivers for hydrologic and biogeochemical processes, as evident in Asia, Africa, and South America which are experiencing rapid population and economic growth. One manifestation of urbanization and economic development is decreases in air quality, increases in dry/wet deposition fluxes, and growing adverse impacts on public health and ecosystem integrity. We examined available long-term (1980-2010) observational data, gathered at weekly intervals, for wet deposition at 19 urban sites in the U.S., and monitoring data (2000-2009) available for 17 urban sites at a monthly scale in East Asia. Our analyses are based on data for four constituents (SO42-, NO3-, Ca2+, and Mg2+); differences in atmospheric chemistry and terrestrial sources of these constituents enabled a robust comparative analysis. We examined intra-annual variability and the long-term temporal trajectories of wet deposition fluxes to discern the relative role of anthropogenic and stochastic hydro-climatic forcing. Here, we show that: (1) temporal variability in wet deposition fluxes follows an exponential probability density function at all sites, evidence that stochasticity of rainfall is the dominant control of wet deposition variability; (2) the mean wet deposition flux, μΩ (ML-2T-1), has decreased in the U.S. over time since enactment of the Clean Air Act, with μΩ having become homogenized across varying hydro-climatic regimes; and (3) in contrast, μΩ values for East Asian cities are 3-10 times higher than U.S. cities, attributed to lax regulatory enforcement. Based on the observed patterns, we suggest a stochastic model that generates ellipses within which the μΩ temporal trajectories are inscribed. In the U.S., anthropogenic forcing (regulations) is dominant in the humid regions, while variability in hydro-climatic forcing explains inter-annual variability in arid regions. Our

  18. Long term monitoring of the chemical composition of precipitation and wet deposition fluxes over three Sahelian savannas

    NASA Astrophysics Data System (ADS)

    Laouali, D.; Galy-Lacaux, C.; Diop, B.; Delon, C.; Orange, D.; Lacaux, J. P.; Akpo, A.; Lavenu, F.; Gardrat, E.; Castera, P.

    2012-04-01

    The purpose of this study is to analyze a long term database of the chemical composition of precipitation at three African dry savanna sites in the Sahel. The precipitation samples were collected during the monsoon season at Agoufou (15°20‧N, 01°29‧W, Mali) from 2004 to 2006, Banizoumbou (13°31‧N, 02°38‧E, Niger) from 1994 to 2009 and Katibougou (12°56‧N, 07°32‧ W, Mali) from 1997 to 2008. pH and major inorganic and organic ions in precipitation were analyzed by ionic chromatography. A characterization of mean precipitation chemistry with the associated wet deposition fluxes for each species is presented. The first important result is that interannual variability of all volume-weighted mean (VWM) concentrations is low, ranging between ±5% and ±25%. Acidity in dry savannas is low and indicates the strong alkaline nature of the precipitation. The average annual pH at Agoufou is 6.28, 5.75 at Banizoumbou and 5.54 at Katibougou. This result is correlated with the important terrigenous contribution measured in the chemical content of precipitation, implying acidity neutralization by mineral species such as Ca2+ and NH4+. Mg2+ and K+ are found to play a minor role in neutralization. Enrichment factor calculations for Ca2+, SO42-, K+ and Mg2+ with respect to the sea reference reveal a significant influence of Saharan and Sahelian crustal sources. VWM concentrations of these species dominate the composition of measured precipitation. An estimation of the potential particulate and gas contribution to the total precipitation composition is given for each site: At Agoufou, the mean relative contribution in rainwater is 80% for particles and 20% for gases, while at the Banizoumbou and Katibougou sites, results indicate 70% for particles and 30% for gases. The high particulate phase contribution to precipitation emphasizes the importance of multiphase processes between gases and particles in the atmospheric chemistry typical of African semi-arid savanna

  19. Rain pH estimation based on the particulate matter pollutants and wet deposition study.

    PubMed

    Singh, Shweta; Elumalai, Suresh Pandian; Pal, Asim Kumar

    2016-09-01

    In forecasting of rain pH, the changes caused by particulate matter (PM) are generally neglected. In regions of high PM concentration like Dhanbad, the role of PM in deciding the rain pH becomes important. Present work takes into account theoretical prediction of rain pH by two methods. First method considers only acid causing gases (ACG) like CO2, SO2 and NOx in pH estimation, whereas, second method additionally accounts for effect of PM (ACG-PM). In order to predict the rain pH, site specific deposited dust that represents local PM was studied experimentally for its impact on pH of neutral water. After incorporation of PM correction factor, it was found that, rain pH values estimated were more representative of the observed ones. Fractional bias (FB) for the ACG-PM method reduced to values of the order of 10(-2) from those with order of 10(-1) for the ACG method. The study confirms neutralization of rain acidity by PM. On account of this, rain pH was found in the slightly acidic to near neutral range, despite of the high sulfate flux found in rain water. Although, the safer range of rain pH blurs the severity of acid rain from the picture, yet huge flux of acidic and other ions get transferred to water bodies, soil and ultimately to the ground water system. Simple use of rain pH for rain water quality fails to address the issues of its increased ionic composition due to the interfering pollutants and thus undermines severity of pollutants transferred from air to rain water and then to water bodies and soil.

  20. Cloud condensation nucleus activity comparison of dry- and wet-generated mineral dust aerosol: the significance of soluble material

    NASA Astrophysics Data System (ADS)

    Garimella, S.; Huang, Y.-W.; Seewald, J. S.; Cziczo, D. J.

    2014-06-01

    This study examines the interaction of clay mineral particles and water vapor for determining the conditions required for cloud droplet formation. Droplet formation conditions are investigated for two common clay minerals, illite and sodium-rich montmorillonite, and an industrially derived sample, Arizona Test Dust. Using wet and dry particle generation coupled to a differential mobility analyzer (DMA) and cloud condensation nuclei counter, the critical activation of the clay mineral particles as cloud condensation nuclei is characterized. Electron microscopy (EM) is used in order to determine non-sphericity in particle shape. It is also used in order to determine particle surface area and account for transmission of multiply charged particles by the DMA. Single particle mass spectrometry and ion chromatography are used to investigate soluble material in wet-generated samples and demonstrate that wet and dry generation yield compositionally different particles. Activation results are analyzed in the context of both κ-Köhler theory (κ-KT) and Frenkel-Halsey-Hill (FHH) adsorption activation theory. This study has two main results: (1) κ-KT is the suitable framework to describe clay mineral nucleation activity. Apparent differences in κ with respect to size arise from an artifact introduced by improper size-selection methodology. For dust particles with mobility sizes larger than ~300 nm, i.e., ones that are within an atmospherically relevant size range, both κ-KT and FHH theory yield similar critical supersaturations. However, the former requires a single hygroscopicity parameter instead of the two adjustable parameters required by the latter. For dry-generated particles, the size dependence of κ is likely an artifact of the shape of the size distribution: there is a sharp drop-off in particle concentration at ~300 nm, and a large fraction of particles classified with a mobility diameter less than ~300 nm are actually multiply charged, resulting in a much

  1. The effects of particle-size distribution and chloride depletion of sea-salt aerosols on estimating atmospheric deposition at a coastal site

    NASA Astrophysics Data System (ADS)

    Harkel, M. J. Ten

    Estimating atmospheric deposition in a coastal region cannot be done without taking care of the size distribution and amount of chloride depletion of sea-salt aerosols. Size distribution of the dry deposition particles is important when the approach of Ulrich (1983, Effects of Accumulation of Air Pollutants in Forest Ecosystems, pp. 33-45. Reidel, Dordrecht) is used to estimate total atmospheric deposition levels in a coastal area. A sodium deposition model demonstrated that the presumption of an equal size of sodium aerosols and chloride, potassium, magnesium and calcium aerosols is not valid in the coastal zone. Modelled aerosol diameter distribution showed that more than 50% of the aerosols deposited in this zone is larger than 20 μm. Besides an anthropogenic source, the reaction of nitric or sulphuric acid with sea-salt aerosols, by which HCl (g) is formed, can be a second source of an excess of chloride in throughflow compared to sodium. The newly formed HCl can deposit as dry deposition on a vegetation, and not as dry bulk deposition. Chloride loss in the bulk deposition at the coastal sites was up to 35% in summertime. Chloride depletion also affects the calculation of potential acid deposition (PAD) in the coastal zone. Part of the NO 3- and excess SO 42- deposition should not be taken into account when calculating the PAD, because it is neutralized by the sea-salt. This effect decreases very soon with increasing distance to the sea. Implementing chloride depletion in calculating yearly PAD at 500 m from the coastline decreased the PAD with 26%. At 2000 m this decrease was 14%. However, in some cases PAD values on a fortnightly base were observed to decrease more than 50% after implementing chloride depletion.

  2. Measuring the emission rate of an aerosol source placed in a ventilated room using a tracer gas: influence of particle wall deposition.

    PubMed

    Bémer, D; Lecler, M T; Régnier, R; Hecht, G; Gerber, J M

    2002-04-01

    A method to measure the emission rate of an airborne pollutant source using a tracer gas was tested in the case of an aerosol source. The influence of particle deposition on the walls of a test room of 72 m3 was studied. The deposition rate of an aerosol of MgCl2 was determined by means of two methods: one based on measuring the aerosol concentration decay inside the ventilated room, the other based on calculation of the material mass balance. The concentration decay was monitored by optical counting and the aerosol mass concentration determined by means of sampling on a filter and analysis of the mass deposited by atomic absorption spectrometry. Four series of measurements were carried out. The curve giving the deposition rate according to the particle aerodynamic diameter (d(ae)) was established and shows deposition rates higher than those predicted using the model of Corner. The decay method gives the best results. The study carried out has shown that the phenomenon of deposition has little effect on the measurement of the aerosol source emission rate using a tracer gas for particles of aerodynamic diameter < 5 microm (underestimation < 25%). For particles of a greater diameter, wall deposition is an extremely limiting factor for the method, the influence of which can, however, be limited by using a test booth of small volume and keeping the sampling duration as short as possible.

  3. Criteria for significance of simultaneous presence of both condensible vapors and aerosol particles on mass transfer (deposition) rates

    NASA Technical Reports Server (NTRS)

    Gokoglu, S. A.

    1987-01-01

    The simultaneous presence of aerosol particles and condensible vapors in a saturated boundary layer which may affect deposition rates to subcooled surfaces because of vapor-particle interactions is discussed. Scavenging of condensible vapors by aerosol particles may lead to increased particle size and decreased vapor mass fraction, which alters both vapor and particle deposition rates. Particles, if sufficiently concentrated, may also coagulate. Criteria are provided to assess the significance of such phenomena when particles are already present in the mainstream and are not created inside the boundary layer via homogeneous nucleation. It is determined that there is direct proportionality with: (1) the mass concentration of both condensible vapors and aerosol particles; and (2) the square of the boundary layer thickness to particle diameter ratio (delta d sub p) square. Inverse proportionality was found for mainstream to surface temperature difference if thermophoresis dominates particle transport. It is concluded that the square of the boundary layer thickness to particle diameter ratio is the most critical factor to consider in deciding when to neglect vapor-particle interactions.

  4. Criteria for significance of simultaneous presence of both condensible vapors and aerosol particles on mass transfer (deposition) rates

    NASA Technical Reports Server (NTRS)

    Gokoglu, S. A.

    1986-01-01

    The simultaneous presence of aerosol particles and condensible vapors in a saturated boundary layer which may affect deposition rates to subcooled surfaces because of vapor-particle interactions is discussed. Scavenging of condensible vapors by aerosol particles may lead to increased particle size and decreased vapor mass fraction, which alters both vapor and particle deposition rates. Particles, if sufficiently concentrated, may also coagulate. Criteria are provided to assess the significance of such phenomena when particles are already present in the mainstream and are not created inside the boundary layer via homogeneous nucleation. It is determined that there is direct proportionality with: (1) the mass concentration of both condensible vapors and aerosol particles; and (2) the square of the boundary layer thickness to particle diameter ratio (delta d sub p) square. Inverse proportionality was found for mainstream to surface temperature difference if thermophoresis dominates particle transport. It is concluded that the square of the boundary layer thickness to particle diameter ratio is the most critical factor to consider in deciding when to neglect vapor-particle interactions.

  5. The grain storage of wet-deposited caesium and strontium by spring wheat - A modelling study based on a field experiment.

    PubMed

    Gärdenäs, Annemieke I; Berglund, S Linnea; Bengtsson, Stefan B; Rosén, Klas

    2017-01-01

    The aims of this study were to extend the Tracey model in order to quantify and to analyse spring wheat's grain storage dynamics of wet-deposited radionuclides. Tracey, a dynamic model of trace element cycling in terrestrial ecosystems, was extended with descriptions of wet-deposition, interception, foliar uptake and radioactive decay. Radionuclide fluxes were set proportional to corresponding water or carbon fluxes, simulated with CoupModel. The extended Tracey was calibrated against experimental data, where (134)Cs and (85)Sr were deposited on spring wheat at six growth stages in 2010 and 2011. Sensitivities of grain storage to wheat's and radionuclide properties were assessed, using the Eikos software, by 1000 Monte Carlo simulations for each of the 48 scenarios (combination of 2 radionuclides, 1 foliar uptake, 2 root uptake approaches, 6 deposition treatments and 2years). Simulations were accepted if simulated grain storage values were within 95% confidence intervals (CI) of measurements. We found that 15% of (134)Cs and (85)Sr simulations for 2011, and 6% of the 2010 simulations met the CI-criterion. Foliar uptake accounted for 99% and 90% of total plant uptake of (134)Cs and (85)Sr, respectively. Mean simulated grain storage at harvest increased with lateness of deposition, as the stored proportion of radionuclide deposited was 0.02% when deposition was before flowering, 2% between flowering and ripening, and 5% (2010) or 10% (2011, late harvest) after ripening, respectively. Similarly, the property that governed grain storage depended on the growth stage at time of deposition; stem and leaf fixation rates (deposition before flowering), grain fixation rates (between flowering and ripening) and grains' interception capacity (after ripening). We conclude that grains' interception capacities can be used to predict grain storage of radionuclides deposited in the riskiest period, i.e. close to harvest.

  6. WRF/Chem study of dry and wet deposition of trifluoroacetic acid produced from the atmospheric degradation of a few short-lived HFCs

    NASA Astrophysics Data System (ADS)

    Kazil, J.; McKeen, S. A.; Kim, S.; Ahmadov, R.; Grell, G. A.; Talukdar, R. K.; Ravishankara, A. R.

    2011-12-01

    HFC-134a (1,1,1,2-tetrafluoroethane) is the prevalent (used in >80% passenger cars and commercial vehicles worldwide) refrigerant in automobile air conditioning units (MACs). With an atmospheric lifetime of ~14 years and a global warming potential (GWP) of 1430 on a 100-year time horizon, HFC-134a does not meet current and expected requirements for MAC refrigerants in many parts of the world. Therefore, substitutes with lower GWP are being sought. One of the simplest way to achieve lower GWP is to use chemicals with shorter atmospheric lifetimes. In this work, we investigate the dry and wet deposition and the rainwater concentration of trifluoroacetic acid (TFA) produced by the atmospheric oxidation of 2,3,3,3-tetrafluoropropene (TFP) and 1,2,3,3,3-pentafluoropropene (PFP). The WRF/Chem model was used to calculate dry and wet TFA deposition over the contiguous USA during the May-September 2006 period that would result from replacing HFC-134a in MACs with a 1:1 molar ratio mixture of 2,3,3,3-tetrafluoropropene (TFP) and 1,2,3,3,3-pentafluoropropene (PFP). The simulation is evaluated by comparing observations of precipitation and sulfate wet deposition at stations of the National Atmospheric Deposition Program (NADP). Simulated precipitation and sulfate wet deposition correlate well with the observations, but exhibit a positive bias for precipitation and a negative bias for sulfate wet deposition. Atmospheric lifetimes of TFP and PFP against oxidation by the hydroxyl radical OH, a prognostic species in WRF/Chem, are ~5 and ~4 days in the simulation, respectively. The model setup allows the attribution of dry and wet TFA deposition to individual source regions (California, Houston, Chicago, and the remaining contiguous USA in this work). TFA deposition is highest in the eastern USA because of numerous large sources and high precipitation in the region. West of the Continental Divide, TFA deposition is significantly lower, and its origin is dominated by emissions from

  7. Morphology, conductivity, and wetting characteristics of PEDOT:PSS thin films deposited by spin and spray coating

    NASA Astrophysics Data System (ADS)

    Zabihi, F.; Xie, Y.; Gao, S.; Eslamian, M.

    2015-05-01

    The goal of this paper is to study the characteristics of PEDOT:PSS thin films and the effects of varying the processing parameters on the structure, functionality, and surface wetting of spun-on and spray-on PEDOT:PSS thin films. PEDOT:PSS is a polymer mixture, which is electrically conductive and transparent and, therefore, is an attractive material for some optoelectronic applications, such as organic and perovskite solar cells. In this work, the films are fabricated using spin coating (a lab-scale method) and spray coating (an up-scalable method). The effects of spinning speed, drying time, and post-annealing temperature on spun-on samples and the effects of the substrate temperature and number of spray passes (deposition layers) on spray-on samples, as well as the effect of precursor solution concentration on both cases are investigated. Various characterization tools, such as AFM, SEM, XRD, confocal laser scanning microscopy (CLSM), and electrical conductivity measurements are used to determine the film roughness, thickness, structure, and morphology. The solution precursor physical data, such as contact angle on glass substrates, viscosity, and interfacial tension, are also obtained within a practical range of temperatures and concentrations. It is found that in both spin and spray coating routes, only well-controlled operating conditions result in the formation of conductive and defect-free PEDOT:PSS films. The formation of PEDOT:PSS thin films with small grains composed of PEDOT forming the core of the grains and PSS forming a shell or coating, which are evenly distributed in a PSS-rich matrix, is favored. Conditions leading to the above-mentioned electrically conductive scenario are identified. Other topics, such as the formation of defects and dewetting, are also elucidated.

  8. Development of observed precipitation and meteorological database to understand the wet deposition and dispersion processes in March 2011

    NASA Astrophysics Data System (ADS)

    Yatagai, Akiyo; Watanabe, Akira; Ishihara, Masahito; Ishihara, Hirohiko; Takara, Kaoru

    2014-05-01

    The transport and diffusion of the radioactive pollutants from the Fukushima-Daiichi NPP inthe atmosphere caused a disaster for residents in and around Fukushima. Studies have sought to understand the transport, diffusion, and deposition process, and to understand the movement of radioactive pollutants through the soil, vegetation, rivers, and groundwater. However, a detailed simulation and understanding of the distribution of radioactive compounds depend on a simulation of precipitation and on the information on the timing of the emission of these radioactive pollutants from the NPP. Further, precipitation type and its amount affect the various transport process of the radioactive nuclides. Hence, this study first examine the qualitative precipitation pattern and timing in March 2011 using X-band radar data from Fukushima University and three dimensional C-band radar data network of Japan Meteorological Agency. Second, by collecting rain-gauge network and other surface meteorological data, we estimate quantitative precipitation and its type (rain/snow) according to the same method used to create APHRODITE daily grid precipitation (Yatagai et al., 2012) and judge of rain/snow (Yasutomi et al., 2011). For example, the data clarified that snowfall was observed on the night of Mar 15 into the morning of Mar 16 throughout Fukushima prefecture. This had an important effect on the radioactive contamination pattern in Fukushima prefecture. The precipitation pattern itself does not show one-on-one correspondence with the contamination pattern. While the pollutants transported northeast of the NPP and through north Kanto (about 200 km southwest of Fukushima and, 100 km north of Tokyo) went to the northeast, the timing of the precipitation causing the fallout, i.e., wet-deposition, is important. Although the hourly Radar-AMeDAS 1-km-mesh precipitation data of JMA are available publically, it does not represent the precipitation pattern in Nakadori, in central Fukushima

  9. Direct Deposition of Gas Phase Generated Aerosol Gold Nanoparticles into Biological Fluids - Corona Formation and Particle Size Shifts

    PubMed Central

    Svensson, Christian R.; Messing, Maria E.; Lundqvist, Martin; Schollin, Alexander; Deppert, Knut; Pagels, Joakim H.; Rissler, Jenny; Cedervall, Tommy

    2013-01-01

    An ongoing discussion whether traditional toxicological methods are sufficient to evaluate the risks associated with nanoparticle inhalation has led to the emergence of Air-Liquid interface toxicology. As a step in this process, this study explores the evolution of particle characteristics as they move from the airborne state into physiological solution. Airborne gold nanoparticles (AuNP) are generated using an evaporation-condensation technique. Spherical and agglomerate AuNPs are deposited into physiological solutions of increasing biological complexity. The AuNP size is characterized in air as mobility diameter and in liquid as hydrodynamic diameter. AuNP:Protein aggregation in physiological solutions is determined using dynamic light scattering, particle tracking analysis, and UV absorption spectroscopy. AuNPs deposited into homocysteine buffer form large gold-aggregates. Spherical AuNPs deposited in solutions of albumin were trapped at the Air-Liquid interface but was readily suspended in the solutions with a size close to that of the airborne particles, indicating that AuNP:Protein complex formation is promoted. Deposition into serum and lung fluid resulted in larger complexes, reflecting the formation of a more complex protein corona. UV absorption spectroscopy indicated no further aggregation of the AuNPs after deposition in solution. The corona of the deposited AuNPs shows differences compared to AuNPs generated in suspension. Deposition of AuNPs from the aerosol phase into biological fluids offers a method to study the protein corona formed, upon inhalation and deposition in the lungs in a more realistic way compared to particle liquid suspensions. This is important since the protein corona together with key particle properties (e.g. size, shape and surface reactivity) to a large extent may determine the nanoparticle effects and possible translocation to other organs. PMID:24086363

  10. Effects of mechanical properties of polymer on ceramic-polymer composite thick films fabricated by aerosol deposition.

    PubMed

    Kwon, Oh-Yun; Na, Hyun-Jun; Kim, Hyung-Jun; Lee, Dong-Won; Nam, Song-Min

    2012-05-22

    Two types of ceramic-polymer composite thick films were deposited on Cu substrates by an aerosol deposition process, and their properties were investigated to fabricate optimized ceramic-based polymer composite thick films for application onto integrated substrates with the advantage of plasticity. When polymers with different mechanical properties, such as polyimide (PI) and poly(methyl methacrylate) (PMMA), are used as starting powders together with α-Al2O3 powder, two types of composite films are formed with different characteristics - surface morphologies, deposition rates, and crystallite size of α-Al2O3. Through the results of micro-Vickers hardness testing, it was confirmed that the mechanical properties of the polymer itself are associated with the performances of the ceramic-polymer composite films. To support and explain these results, the microstructures of the two types of polymer powders were observed after planetary milling and an additional modeling test was carried out. As a result, we could conclude that the PMMA powder is distorted by the impact of the Al2O3 powder, so that the resulting Al2O3-PMMA composite film had a very small amount of PMMA and a low deposition rate. In contrast, when using PI powder, the Al2O3-PI composite film had a high deposition rate due to the cracking of PI particles. Consequently, it was revealed that the mechanical properties of polymers have a considerable effect on the properties of the resulting ceramic-polymer composite thick films.

  11. Fe-Si-Cr/PTFE magnetic composite thick films on polyethylene terephthalate sheets for near field communications by aerosol deposition.

    PubMed

    Kim, Hyung-Jun; Nam, Song-Min; Koh, Jung-Hyuk

    2014-10-01

    Thick film growth of Fe-Si-Cr/poly-tetra-fluoro-ethylene (PTFE) composite films on polyethylene terephthalate (PET) sheets was investigated by aerosol deposition (AD) as a magnetic absorber for near field communication. The Fe-Si-Cr flakes were crushed to micro flakes smaller than 1 μm after the deposition, and formed dense microstructure on the PET sheets. The Fe-Si-Cr/PTFE composite thick films using 0.2 wt.% PTFE starting powder showed dense and uniform microstructure compared to the 0.5 wt.% film. The real relative permeability /' and the imaginary permeability μ" of Fe-Si-Cr/PTFE composite thick films using the 0.2 wt.% PTFE starting powder were 13.1 and 2.9 at 13.56 MHz, respectively. In the case of 0.5 wt.%, μ' and μ" respectively decreased to 7.4 and 1.0 at 13.56 MHz caused by adding PTFE.

  12. Continental-scale assessment of long-term trends in wet deposition trajectories: Role of anthropogenic and hydro-climatic drivers

    NASA Astrophysics Data System (ADS)

    Park, J.; Gall, H. E.; Niyogi, D.; Rao, S.

    2012-12-01

    The global trend of increased urbanization, and associated increased intensity of energy and material consumption and waste emissions, has contributed to shifts in the trajectories of aquatic, terrestrial, and atmospheric environments. Here, we focus on continental-scale spatiotemporal patterns in two atmospheric constituents (nitrate and sulfate), whose global biogeochemical cycles have been dramatically altered by emissions from mobile and fixed sources in urbanized and industrialized regions. The observed patterns in wet deposition fluxes of nitrate and sulfate are controlled by (1) natural hydro-climatic forcing, and (2) anthropogenic forcing (emissions and regulatory control), both of which are characterized by stochasticity and non-stationarity. We examine long-term wet deposition records in the U.S., Europe, and East Asia to evaluate how anthropogenic and natural forcing factors jointly contributed to the shifting temporal patterns of wet deposition fluxes at continental scales. These data offer clear evidence for successful implementation of regulatory controls and widespread adoption of technologies contributed to improving water quality and mitigation of adverse ecological impacts. We developed a stochastic model to project the future trajectories of wet deposition fluxes in emerging countries with fast growing urban areas. The model generates ellipses within which projected wet deposition flux trajectories are inscribed, similar to the trends in observational data. The shape of the ellipses provides information regarding the relative dominance of anthropogenic (e.g., industrial and urban emissions) versus hydro-climatic drivers (e.g., rainfall patterns, aridity index). Our analysis facilitates projections of the trajectory shift as a result of urbanization and other land-use changes, climate change, and regulatory enforcement. We use these observed data and the model to project likely trajectories for rapidly developing countries (BRIC), with a

  13. Development of infrared photothermal deflection spectroscopy (mirage effect) for analysis of condensed-phase aerosols collected in a micro-orifice uniform deposit impactor.

    PubMed

    Dada, Oluwatosin O; Bialkowski, Stephen E

    2008-12-01

    The potential of mid-infrared photothermal deflection spectrometry for aerosol analysis is demonstrated. Ammonium nitrate aerosols are deposited on a flat substrate using a micro-orifice uniform deposit impactor (MOUDI). Photothermal spectroscopy with optical beam deflection (mirage effect) is used to detect deposited aerosols. Photothermal deflection from aerosols is measured by using pulsed infrared laser light to heat up aerosols collected on the substrate. The deflection signal is obtained by measuring the position of a spot from a beam of light as it passes near the heated surface. The results indicate non-rotating impaction as the preferred MOUDI impaction method. Energy-dependent photothermal measurement shows a linear relationship between signal and laser intensity, and no loss of signal with time is observed. The detection limit from the signal-mass curve is 7.31 ng. For 30 minutes collection time and 30 L/min flow rate of the impactor, the limit of detection in terms of aerosol mass concentration is 0.65 microg m(-3).

  14. Measurements of electrodynamic effects on the deposition of MDI and DPI aerosols in a replica cast of human oral-pharyngeal-laryngeal airways.

    PubMed

    Ali, Mohammed; Mazumder, Malay K; Martonen, Ted B

    2009-03-01

    Metered dose inhalers (MDIs) and dry powder inhalers (DPIs) are popular drug delivery devices used in the treatment of respiratory diseases such as asthma and chronic obstructive pulmonary disease (COPD). Integrated effects of electrostatic charges and aerodynamic sizes on the deposition of MDI and DPI particles in a replica cast of human oral-pharyngeal-laryngeal (OPL) airways were examined. Experimental aerosols were generated from commercially available MDI and DPI devices. They are the trademarked brands of the same pharmaceutical company, and contain the same amounts of different drugs. Inhalations were administered as boluses and characterized with an Electronic Single Particle Aerodynamic Relaxation Time (ESPART) analyzer before and after passing through the cadaver-based OPL cast. The MDI and DPI aerosols were not only of different sizes but also carried different positive, negative and zero electrostatic charges; 42.2% of the total number of DPI particles was charged in comparison to 6% of those produced by the MDI. Electrodynamic properties (e.g., charges and sizes) played significant roles on the behavior and deposition of aerosols in the OPL airways. As detailed herein, deposition fractions of the total (charged and uncharged) DPI aerosols were 21.5% in contrast to 2.8% for the MDI aerosols, whereas the charged particle deposition for the DPI was 46.7% in contrast to 22.5% for the MDI. Particle losses in the OPL passages were greater for the DPI than the MDI as the former generated more charged particles than the latter. This finding is consistent with results reported by other researchers but contradicts the observation of another investigator where MDI losses were reported as being higher than those for DPIs. The chief reason for this difference may be that the latter study did not account for the electrical properties of aerosol particles, but only for their mechanical properties. Because the measured deposition efficiencies of MDI and DPI aerosols

  15. Addressing the ice nucleating abilities of marine aerosol: A combination of deposition mode laboratory and field measurements

    NASA Astrophysics Data System (ADS)

    Ladino, L. A.; Yakobi-Hancock, J. D.; Kilthau, W. P.; Mason, R. H.; Si, M.; Li, J.; Miller, L. A.; Schiller, C. L.; Huffman, J. A.; Aller, J. Y.; Knopf, D. A.; Bertram, A. K.; Abbatt, J. P. D.

    2016-05-01

    This study addresses, through two types of experiments, the potential for the oceans to act as a source of atmospheric ice-nucleating particles (INPs). The INP concentration via deposition mode nucleation was measured in situ at a coastal site in British Columbia in August 2013. The INP concentration at conditions relevant to cirrus clouds (i.e., -40 °C and relative humidity with respect to ice, RHice = 139%) ranged from 0.2 L-1 to 3.3 L-1. Correlations of the INP concentrations with levels of anthropogenic tracers (i.e., CO, SO2, NOx, and black carbon) and numbers of fluorescent particles do not indicate a significant influence from anthropogenic sources or submicron bioaerosols, respectively. Additionally, the INPs measured in the deposition mode showed a poor correlation with the concentration of particles with sizes larger than 500 nm, which is in contrast with observations made in the immersion freezing mode. To investigate the nature of particles that could have acted as deposition INP, laboratory experiments with potential marine aerosol particles were conducted under the ice-nucleating conditions used in the field. At -40 °C, no deposition activity was observed with salt aerosol particles (sodium chloride and two forms of commercial sea salt: Sigma-Aldrich and Instant Ocean), particles composed of a commercial source of natural organic matter (Suwannee River humic material), or particle mixtures of sea salt and humic material. In contrast, exudates from three phytoplankton (Thalassiosira pseudonana, Nanochloris atomus, and Emiliania huxleyi) and one marine bacterium (Vibrio harveyi) exhibited INP activity at low RHice values, down to below 110%. This suggests that the INPs measured at the field site were of marine biological origins, although we cannot rule out other sources, including mineral dust.

  16. Impact of the modal aerosol scheme GLOMAP-mode on aerosol forcing in the Hadley Centre Global Environmental Model

    NASA Astrophysics Data System (ADS)

    Bellouin, N.; Mann, G. W.; Woodhouse, M. T.; Johnson, C.; Carslaw, K. S.; Dalvi, M.

    2013-03-01

    The Hadley Centre Global Environmental Model (HadGEM) includes two aerosol schemes: the Coupled Large-scale Aerosol Simulator for Studies in Climate (CLASSIC), and the new Global Model of Aerosol Processes (GLOMAP-mode). GLOMAP-mode is a modal aerosol microphysics scheme that simulates not only aerosol mass but also aerosol number, represents internally-mixed particles, and includes aerosol microphysical processes such as nucleation. In this study, both schemes provide hindcast simulations of natural and anthropogenic aerosol species for the period 2000-2006. HadGEM simulations of the aerosol optical depth using GLOMAP-mode compare better than CLASSIC against a data-assimilated aerosol re-analysis and aerosol ground-based observations. Because of differences in wet deposition rates, GLOMAP-mode sulphate aerosol residence time is two days longer than CLASSIC sulphate aerosols, whereas black carbon residence time is much shorter. As a result, CLASSIC underestimates aerosol optical depths in continental regions of the Northern Hemisphere and likely overestimates absorption in remote regions. Aerosol direct and first indirect radiative forcings are computed from simulations of aerosols with emissions for the year 1850 and 2000. In 1850, GLOMAP-mode predicts lower aerosol optical depths and higher cloud droplet number concentrations than CLASSIC. Consequently, simulated clouds are much less susceptible to natural and anthropogenic aerosol changes when the microphysical scheme is used. In particular, the response of cloud condensation nuclei to an increase in dimethyl sulphide emissions becomes a factor of four smaller. The combined effect of different 1850 baselines, residence times, and abilities to affect cloud droplet number, leads to substantial differences in the aerosol forcings simulated by the two schemes. GLOMAP-mode finds a present-day direct aerosol forcing of -0.49 W m-2 on a global average, 72% stronger than the corresponding forcing from CLASSIC. This

  17. Modelling of primary aerosols in the chemical transport model MOCAGE: development and evaluation of aerosol physical parameterizations

    NASA Astrophysics Data System (ADS)

    Sič, B.; El Amraoui, L.; Marécal, V.; Josse, B.; Arteta, J.; Guth, J.; Joly, M.; Hamer, P.

    2014-04-01

    This paper deals with recent improvements to the chemical transport model of Météo-France MOCAGE that consists of updates to different aerosol parameterizations. MOCAGE only contains primary aerosol species. We introduced important changes to the aerosol parameterization concerning emissions, wet deposition and sedimentation. For the emissions, size distribution and wind calculations are modified for desert dust aerosols, and a surface sea temperature dependant source function is introduced for sea salt aerosols. Wet deposition is modified toward a more physically realistic representation by introducing re-evaporation of falling rain and snowfall scavenging, and by changing in-cloud scavenging scheme along with calculations of precipitation cloud cover and rain properties. The sedimentation scheme update includes changes regarding the stability and viscosity calculations. Independent data from satellites (MODIS, SEVIRI), the ground (AERONET), and a model inter-comparison project (AeroCom) is compared with MOCAGE simulations and showed that the introduced changes brought a significant improvement on aerosol representation, properties and global distribution. Emitted quantities of desert dust and sea salt, as well their lifetimes, moved closer towards values of AeroCom estimates and the multi-model average. When comparing the model simulations with MODIS aerosol optical depth (AOD) observations over the oceans, the updated model configuration shows a decrease in the bias (from 0.032 to 0.002) and a better correlation (from 0.062 to 0.322) in terms of the geographical distribution and the temporal variability. The updates corrected a strong positive bias in the sea salt representation at high latitudes (from 0.153 to 0.026), and a negative bias in the desert dust representation in the African dust outflow region (from -0.179 to -0.051). The updates in sedimentation produced a modest difference; the bias with MODIS data from 0.002 in the updated configuration went to

  18. Effect of microgravity and hypergravity on deposition of 0.5- to 3-micron-diameter aerosol in the human lung

    NASA Technical Reports Server (NTRS)

    Darquenne, C.; Paiva, M.; West, J. B.; Prisk, G. K.

    1997-01-01

    We measured intrapulmonary deposition of 0. 5-, 1-, 2-, and 3-micron-diameter particles in four subjects on the ground (1 G) and during parabolic flights both in microgravity (microG) and at approximately 1.6 G. Subjects breathed aerosols at a constant flow rate (0.4 l/s) and tidal volume (0.75 liter). At 1 G and approximately 1.6 G, deposition increased with increasing particle size. In microG, differences in deposition as a function of particle size were almost abolished. Deposition was a nearly linear function of the G level for 2- and 3-micron-diameter particles, whereas for 0.5- and 1.0-micron-diameter particles, deposition increased less between microG and 1 G than between 1 G and approximately 1.6 G. Comparison with numerical predictions showed good agreement for 1-, 2-, and 3-micron-diameter particles at 1 and approximately 1.6 G, whereas the model consistently underestimated deposition in microG. The higher deposition observed in microG compared with model predictions might be explained by a larger deposition by diffusion because of a higher alveolar concentration of aerosol in microG and to the nonreversibility of the flow, causing additional mixing of the aerosols.

  19. Timing of wet episodes in Atacama Desert over the last 15 ka. The Groundwater Discharge Deposits (GWD) from Domeyko Range at 25°S.

    NASA Astrophysics Data System (ADS)

    Sáez, Alberto; Godfrey, Linda V.; Herrera, Christian; Chong, Guillermo; Pueyo, Juan J.

    2016-08-01

    A chronologically robust reconstruction of timing and dynamics of millennial time scale wet episodes encompassing the entire Atacama Desert during the last 15 ka has been constructed. To accomplish this, a new composite paleoclimatic record from Groundwater Discharge Deposits (GWD) in the Sierra de Varas (Domeyko Range, southern Atacama in Chile at 25°S) has been compiled and compared with other published paleohydrologic records from the Atacama region. In Sierra de Varas (SV), three millennial timescale wet climate phases have been characterized: around 14.5 ka cal BP, 12.2-9.8 ka cal BP, and 4.7 ka cal BP to the present day. These wet phases are interpreted from intervals of GWD facies formed during periods when the springs were active. GWD facies include: (1) black organic peat, rooted mudstones and sandstones formed in local wetland environments, and (2) gypsum-carbonate rich layers formed by interstitial growth. GWD intervals alternate with gravelly alluvial material deposited during arid phases. A trend towards less humid conditions during the Late Holocene wet episode characterizes GWD sedimentary series in Sierra the Varas, suggesting the onset of a dry episode over the last few centuries. Around 0.7 ka BP a very short wet episode is recorded in the central part of the desert suggesting this was the time of maximum humidity for the entire late Holocene wet period. A brief arid phase occurred between 1.5 and 2.0 ka BP indicated by the absence of GWD in the Domeyko Range. The paleoclimatic reconstruction encompassing the entire Atacama region shows that both the intensity and occurrence of wetter conditions were governed mainly by the distance to the source of moisture, and secondarily by the elevation of the sites. In the northern Atacama (16-20°S), four wet phases fed by N-NE summer monsoon precipitations have been proposed: Tauca phase (18-14 ka cal BP) and Coipasa phase (13-10 ka cal BP) during the Late Glacial, followed by Early Holocene and Late

  20. Improved solid aerosol generator

    DOEpatents

    Prescott, D.S.; Schober, R.K.; Beller, J.

    1988-07-19

    An improved solid aerosol generator used to produce a gas borne stream of dry, solid particles of predetermined size and concentration. The improved solid aerosol generator nebulizes a feed solution of known concentration with a flow of preheated gas and dries the resultant wet heated aerosol in a grounded, conical heating chamber, achieving high recovery and flow rates. 2 figs.

  1. Solid aerosol generator

    DOEpatents

    Prescott, Donald S.; Schober, Robert K.; Beller, John

    1992-01-01

    An improved solid aerosol generator used to produce a gas borne stream of dry, solid particles of predetermined size and concentration. The improved solid aerosol generator nebulizes a feed solution of known concentration with a flow of preheated gas and dries the resultant wet heated aerosol in a grounded, conical heating chamber, achieving high recovery and flow rates.

  2. Solid aerosol generator

    DOEpatents

    Prescott, D.S.; Schober, R.K.; Beller, J.

    1992-03-17

    An improved solid aerosol generator used to produce a gas borne stream of dry, solid particles of predetermined size and concentration is disclosed. The improved solid aerosol generator nebulizes a feed solution of known concentration with a flow of preheated gas and dries the resultant wet heated aerosol in a grounded, conical heating chamber, achieving high recovery and flow rates. 2 figs.

  3. Comparison of Mercury Mass Loading in Streams to Wet and Dry Atmospheric Deposition in Watersheds of the Western US: Evidence for Non-Atmospheric Mercury Sources

    NASA Astrophysics Data System (ADS)

    Domagalski, J. L.; Majewski, M. S.; Alpers, C. N.; Eckley, C.

    2015-12-01

    Many streams in the western United States (US) are listed as impaired by mercury (Hg), and it is important to understand the magnitudes of the various sources in order to implement management strategies. Atmospheric deposition of Hg and can be a major source of aquatic contamination, along with mine wastes, and other sources. Prior studies in the eastern US have shown that streams deliver less than 50% of the atmospherically deposited Hg on an annual basis. In this study, we compared annual stream Hg loads for 20 watersheds in the western US to measured wet and modeled dry deposition. Land use varies from undisturbed to mixed (agricultural, urban, forested, mining). Data from the Mercury Deposition Network was used to estimate Hg input from precipitation. Dry deposition was not directly measured, but can be modeled using the Community Multi-scale Air Quality model. At an undeveloped watershed in the Rocky Mountains, the ratio of stream Hg load to atmospheric deposition was 0.2 during a year of average precipitation. In contrast, at the Carson River in Nevada, with known Hg contamination from historical silver mining with Hg amalgamation, stream export exceeded atmospheric deposition by a factor of 60, and at a small Sierran watershed with gold mining, the ratio was 70. Larger watersheds with mixed land uses, tend to have lower ratios of stream export relative to atmospheric deposition suggesting storage of Hg. The Sacramento River was the largest watershed for which Hg riverine loads were available with an average ratio of stream Hg export to atmospheric deposition of 0.10. Although Hg was used in upstream historical mining operations, the downstream river Hg load is partially mitigated by reservoirs, which trap sediment. This study represents the first compilation of riverine Hg loads in comparison to atmospheric deposition on a regional scale; the approach may be useful in assessing the relative importance of atmospheric and non-atmospheric Hg sources.

  4. Massive Volcanic SO2 Oxidation and Sulphate Aerosol Deposition in Cenozoic North America

    EPA Science Inventory

    Volcanic eruptions release a large amount of sulphur dioxide (SO2) into the atmosphere. SO2 is oxidized to sulphate and can subsequently form sulphate aerosol, which can affect the Earth's radiation balance, biologic productivity and high-altitude ozone co...

  5. Nanostructured Thin Film Synthesis by Aerosol Chemical Vapor Deposition for Energy Storage Applications

    NASA Astrophysics Data System (ADS)

    Chadha, Tandeep S.

    Renewable energy sources offer a viable solution to the growing energy demand while mitigating concerns for greenhouse gas emissions and climate change. This has led to a tremendous momentum towards solar and wind-based energy harvesting technologies driving efficiencies higher and costs lower. However, the intermittent nature of these energy sources necessitates energy storage technologies, which remain the Achilles heel in meeting the renewable energy goals. This dissertation focusses on two approaches for addressing the needs of energy storage: first, targeting direct solar to fuel conversion via photoelectrochemical water-splitting and second, improving the performance of current rechargeable batteries by developing new electrode architectures and synthesis processes. The aerosol chemical vapor deposition (ACVD) process has emerged as a promising single-step approach for nanostructured thin film synthesis directly on substrates. The relationship between the morphology and the operating parameters in the process is complex. In this work, a simulation based approach has been developed to understand the relationship and acquire the ability of predicting the morphology. These controlled nanostructured morphologies of TiO2 , compounded with gold nanoparticles of various shapes, are used for solar water-splitting applications. Tuning of light absorption in the visible-light range along with reduced electron-hole recombination in the composite structures has been demonstrated. The ACVD process is further extended to a novel single-step synthesis of nanostructured TiO2 electrodes directly on the current collector for applications as anodes in lithium-ion batteries, mainly for electric vehicles and hybrid electric vehicles. The effect of morphology of the nanostructures has been investigated via experimental studies and electrochemical transport modelling. Results demonstrate the exceptional performance of the single crystal one-dimensional nanostructures over granular

  6. Aerosol-Chemical Vapor Deposition Method For Synthesis of Nanostructured Metal Oxide Thin Films With Controlled Morphology

    SciTech Connect

    An, Woo-Jin; Thimsen, Elijah J.; Biswas, Pratim

    2010-01-07

    An aerosol-chemical vapor deposition (ACVD) was designed to deposit nanostructured metal oxide films with controlled morphologies. Characteristic times of the different processes governing deposition of the film were used to establish the relationship of process parameters to the resultant morphology of the film. Titanium dioxide (TiO{sub 2}) films were synthesized with different morphologies: dense, columnar, granular, and branched tree-type structures. The developed ACVD process was also used to deposit columnar nickel oxide (NiO) films. The various films with well-controlled characteristics (length, morphology) were used to establish the performance in solar energy applications, such as photosplitting of water to produce hydrogen. Columnar TiO{sub 2} films of 1.6 μm length with a platinum wire counter electrode resulted in 15.58% hydrogen production efficiencies under UV light illumination, which was 2.50 times higher than dense TiO{sub 2} films with a platinum wire counter electrode. On replacing the Pt counter electrode with a columnar NiO film, efficiencies of 10.98% were obtained.

  7. Deposition and dispersion of 1-micrometer aerosol boluses in the human lung: effect of micro- and hypergravity

    NASA Technical Reports Server (NTRS)

    Darquenne, C.; West, J. B.; Prisk, G. K.

    1998-01-01

    We performed bolus inhalations of 1-micrometer particles in four subjects on the ground (1 G) and during parabolic flights both in microgravity (microG) and in approximately 1.6 G. Boluses of approximately 70 ml were inhaled at different points in an inspiration from residual volume to 1 liter above functional residual capacity. The volume of air inhaled after the bolus [the penetration volume (Vp)] ranged from 200 to 1,500 ml. Aerosol concentration and flow rate were continuously measured at the mouth. The deposition, dispersion, and position of the bolus in the expired gas were calculated from these data. For Vp >/=400 ml, both deposition and dispersion increased with Vp and were strongly gravity dependent, with the greatest deposition and dispersion occurring for the largest G level. At Vp = 800 ml, deposition and dispersion increased from 33.9% and 319 ml in microG to 56.9% and 573 ml at approximately 1.6 G, respectively (P < 0.05). At each G level, the bolus was expired at a smaller volume than Vp, and this volume became smaller with increasing Vp. Although dispersion was lower in microG than in 1 G and approximately 1.6 G, it still increased steadily with increasing Vp, showing that nongravitational ventilatory inhomogeneity is partly responsible for dispersion in the human lung.

  8. Modeling dry and wet deposition of sulfate, nitrate, and ammonium ions in Jiuzhaigou National Nature Reserve, China using a source-oriented CMAQ model: Part I. Base case model results.

    PubMed

    Qiao, Xue; Tang, Ya; Hu, Jianlin; Zhang, Shuai; Li, Jingyi; Kota, Sri Harsha; Wu, Li; Gao, Huilin; Zhang, Hongliang; Ying, Qi

    2015-11-01

    A source-oriented Community Multiscale Air Quality (CMAQ) model driven by the meteorological fields generated by the Weather Research and Forecasting (WRF) model was used to study the dry and wet deposition of nitrate (NO3(-)), sulfate (SO4(2-)), and ammonium (NH4(+)) ions in the Jiuzhaigou National Nature Reserve (JNNR), China from June to August 2010 and to identify the contributions of different emission sectors and source regions that were responsible for the deposition fluxes. The model performance is evaluated in this paper and the source contribution analyses are presented in a companion paper. The results show that WRF is capable of reproducing the observed precipitation rates with a Mean Normalized Gross Error (MNGE) of 8.1%. Predicted wet deposition fluxes of SO4(2-) and NO3(-) at the Long Lake (LL) site (3100 m a.s.l.) during the three-month episode are 2.75 and 0.34 kg S(N) ha(-1), which agree well with the observed wet deposition fluxes of 2.42 and 0.39 kg S(N) ha(-1), respectively. Temporal variations in the weekly deposition fluxes at LL are also well predicted. Wet deposition flux of NH4(+) at LL is over-predicted by approximately a factor of 3 (1.60 kg N ha(-1)vs. 0.56 kg N ha(-1)), likely due to missing alkaline earth cations such as Ca(2+) in the current CMAQ simulations. Predicted wet deposition fluxes are also in general agreement with observations at four Acid Deposition Monitoring Network in East Asia (EANET) sites in western China. Predicted dry deposition fluxes of SO4(2-) (including gas deposition of SO2) and NO3(-) (including gas deposition of HNO3) are 0.12 and 0.12 kg S(N) h a(-1) at LL and 0.07 and 0.08 kg S(N) ha(-1) at Jiuzhaigou Bureau (JB) in JNNR, respectively, which are much lower than the corresponding wet deposition fluxes. Dry deposition flux of NH4(+) (including gas deposition of NH3) is 0.21 kg N ha(-1) at LL, and is also much lower than the predicted wet deposition flux. For both dry and wet deposition fluxes, predictions

  9. Changes in future air quality, deposition, and aerosol-cloud interactions under future climate and emission scenarios

    NASA Astrophysics Data System (ADS)

    Glotfelty, Timothy; Zhang, Yang; Karamchandani, Prakash; Streets, David G.

    2016-08-01

    The prospect of global climate change will have wide scale impacts, such as ecological stress and human health hazards. One aspect of concern is future changes in air quality that will result from changes in both meteorological forcing and air pollutant emissions. In this study, the GU-WRF/Chem model is employed to simulate the impact of changing climate and emissions following the IPCC AR4 SRES A1B scenario. An average of 4 future years (2020, 2030, 2040, and 2050) is compared against an average of 2 current years (2001 and 2010). Under this scenario, by the Mid-21st century global air quality is projected to degrade with a global average increase of 2.5 ppb in the maximum 8-hr O3 level and of 0.3 μg m-3 in 24-hr average PM2.5. However, PM2.5 changes are more regional due to regional variations in primary aerosol emissions and emissions of gaseous precursor for secondary PM2.5. Increasing NOx emissions in this scenario combines with a wetter climate elevating levels of OH, HO2, H2O2, and the nitrate radical and increasing the atmosphere's near surface oxidation state. This differs from findings under the RCP scenarios that experience declines in OH from reduced NOx emissions, stratospheric recovery of O3, and increases in CH4 and VOCs. Increasing NOx and O3 levels enhances the nitrogen and O3 deposition, indicating potentially enhanced crop damage and ecosystem stress under this scenario. The enhanced global aerosol level results in enhancements in aerosol optical depth, cloud droplet number concentration, and cloud optical thickness. This leads to dimming at the Earth's surface with a global average reduction in shortwave radiation of 1.2 W m-2. This enhanced dimming leads to a more moderate warming trend and different trends in radiation than those found in NCAR's CCSM simulation, which does not include the advanced chemistry and aerosol treatment of GU-WRF/Chem and cannot simulate the impacts of changing climate and emissions with the same level of detailed

  10. Changes in future air quality, deposition, and aerosol-cloud interactions under future climate and emission scenarios

    SciTech Connect

    Glotfelty, Timothy; Zhang, Yang; Karamchandani, Prakash; Streets, David G.

    2016-08-01

    The prospect of global climate change will have wide scale impacts, such as ecological stress and human health hazards. One aspect of concern is future changes in air quality that will result from changes in both meteorological forcing and air pollutant emissions. In this study, the GU-WRF/Chem model is employed to simulate the impact of changing climate and emissions following the IPCC AR4 SRES A1B scenario. An average of 4 future years (2020, 2030, 2040, and 2050) is compared against an average of 2 current years (2001 and 2010). Under this scenario, by the Mid-21st century global air quality is projected to degrade with a global average increase of 2.5 ppb in the maximum 8-hr O3 level and of 0.3 mg m3 in 24-hr average PM2.5. However, PM2.5 changes are more regional due to regional variations in primary aerosol emissions and emissions of gaseous precursor for secondary PM2.5. Increasing NOx emissions in this scenario combines with a wetter climate elevating levels of OH, HO2, H2O2, and the nitrate radical and increasing the atmosphere’s near surface oxidation state. This differs from findings under the RCP scenarios that experience declines in OH from reduced NOx emissions, stratospheric recovery of O3, and increases in CH4 and VOCs. Increasing NOx and O3 levels enhances the nitrogen and O3 deposition, indicating potentially enhanced crop damage and ecosystem stress under this scenario. The enhanced global aerosol level results in enhancements in aerosol optical depth, cloud droplet number concentration, and cloud optical thickness. This leads to dimming at the Earth’s surface with a global average reduction in shortwave radiation of 1.2 W m2 . This enhanced dimming leads to a more moderate warming trend and different trends in radiation than those found in NCAR’s CCSM simulation, which does not include the advanced chemistry and aerosol

  11. Recent Rainfall and Aerosol Chemistry From Bermuda

    NASA Astrophysics Data System (ADS)

    Landing, W. M.; Shelley, R.; Kadko, D. C.

    2014-12-01

    This project was devoted to testing the use of Be-7 as a tracer for quantifying trace element fluxes from the atmosphere to the oceans. Rainfall and aerosol samples were collected between June 15, 2011 and July 27, 2013 at the Bermuda Institute of Ocean Sciences (BIOS) located near the eastern end of the island of Bermuda. Collectors were situated near ground level, clear of surrounding vegetation, at a meteorological monitoring station in front of the BIOS laboratory, about 10 m above sea level. This is a Bermuda Air Quality Program site used for ambient air quality monitoring. To quantify the atmospheric deposition of Be-7, plastic buckets were deployed for collection of fallout over ~3 week periods. Wet deposition was collected for trace element analysis using a specially modified "GEOTRACES" N-CON automated wet deposition collector. Aerosol samples were collected with a Tisch TE-5170V-BL high volume aerosol sampler, modified to collect 12 replicate samples on acid-washed 47mm diameter Whatman-41 filters, using procedures identical to those used for the US GEOTRACES aerosol program (Morton et al., 2013). Aerosol and rainfall samples were analyzed for total Na, Mg, Al, P, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Rb, Sr, Zr, Cd, Sb, Ba, La, Ce, Nd, Pb, Th, and U using ICPMS. Confirming earlier data from Bermuda, strong seasonality in rainfall and aerosol loading and chemistry was observed, particularly for aerosol and rainfall Fe concentrations when Saharan dust arrives in July/August with SE trajectories.

  12. Fabrication of LiCoO 2 cathode powder for thin film battery by aerosol flame deposition

    NASA Astrophysics Data System (ADS)

    Lee, Taewon; Cho, Kihyun; Oh, Jangwon; Shin, Dongwook

    Crystalline LiCoO 2 nano-particles for thin film battery were synthesized and deposited by aerosol flame deposition (AFD). The aqueous precursor solution of the lithium nitrate and cobalt acetate was atomized with an ultrasonic vibrator and subsequently carried into the central tube of the torch by flowing dry Ar gas. LiCoO 2 were formed by oxy-hydrogen flame and deposited on a substrate placed in a heating stage. The deposited soot film composed of nano-sized particles was subsequently consolidated into a dense film by high temperature heat treatment at 500-800 °C for 5 h and characterized by SEM, XRD, and Raman spectroscopy. The crystalline carbonates and oxide were first formed by the deposition and the subsequent heat treatment converted those to LiCoO 2. The FWHMs of the XRD peaks were reduced and their intensity increased as the heat treatment temperature increased, which is due to improved crystallinity. When judged from the low enough cation mixing and well-developed layered structure, it is believed that the LiCoO 2 film satisfied the quality standard for the real application. SEM measurements showed that LiCoO 2 were nano-crystalline structure with the average particle size <70 nm and the particle size increased with the increase of heat treatment temperature. The thickness of thin film LiCoO 2 before the consolidation process was about 15 μm and reduced to about 4 μm after sintering.

  13. Dissolved organic nitrogen in wet deposition in a coastal city (Keelung) of the southern East China Sea: Origin, molecular composition and flux

    NASA Astrophysics Data System (ADS)

    Chen, You-Xin; Chen, Hung-Yu; Wang, Wei; Yeh, Jun-Xian; Chou, Wen-Chen; Gong, Gwo-Ching; Tsai, Fu-Jung; Huang, Shih-Jen; Lin, Cheng-Ting

    2015-07-01

    In this study, we collected and analyzed rainwater samples from Keelung, Taiwan, which is a coastal city located south of the East China Sea (ECS). From January 2012 until June 2013, 78 rainwater samples were collected over an 18-month period and were analyzed to examine the total dissolved nitrogen (TDN) and major ions in the rainwater. TDN can be divided into dissolved inorganic nitrogen (DIN) and dissolved organic nitrogen (DON). This study, which focused on the composition of DON, is the first study to employ ultrafiltration to separate DON in wet deposition into low molecular weight-DON (LMW-DON) and high molecular weight-DON (HMW-DON). The concentrations of dissolved nitrogen species observed in the research area between November 2012 and April 2013 were relatively high, whereas those observed between May 2013 and October 2012 were relatively low. The patterns of changes over time were similar to those of non-sea-salt (nss) ions. The concentration of nss-ions was high during months in which the total dissolved nitrogen concentration was also high, which occur frequently during the spring and winter. In addition, the concentration of nss-ions was low during months in which the TDN concentration was low, which primarily occurs during the summer. The amounts of DIN and DON accounted for 63 ± 5% and 37 ± 5% of the TDN, respectively, and the percentage of the DIN was higher during the spring and winter. The concentrations of LMW-DON and HMW-DON, which accounted for 84 ± 3% and 16 ± 3% of the DON, respectively, were both high in the winter and low in the summer. The percentage of LMW-DON increased in the summer, possibly because of the numerous oceanic air masses and typhoons. Furthermore, the percentage of HMW-DON increased in the spring, potentially due to biomass burning during agricultural activities. Regarding the wet deposition fluxes, the DIN (197 ± 10.27 mmol m-2 yr-1) and DON (129 ± 6.82 mmol m-2 yr-1) accounted for approximately 64% and 36% of the

  14. YBa2Cu3O6+xSemiconductors Fabricated Using the Aerosol Deposition Method for IR Sensors.

    PubMed

    Jung, Hye-Rin; Lee, Tae-He; Lee, Sung-Gap

    2015-03-01

    In this study, YBa2Cu306+x (YBCO) thick films were investigated for their application in uncooled microbolometers. YBCO powders were prepared using the conventional mixed oxide method and were deposited on an SiO2/Si substrate using the aerosol deposition method (ADM) at room temperature. As a result of thermogravimetry and differential thermal analysis (TG-DTA) of YBCO powder, an endothermic peak was observed at approximately 820 °C. The powder was calcined at 880 °C. The deposited film were annealed at 600-750 °C (O2:Ar = 1:1, pO2) and their structural and electrical properties were investigated at varying annealing temperatures. From X-ray diffraction (XRD) results, all films displayed the typical XRD patterns of the tetragonal phase and the second phase was observed. The thickness of all the YBCO thick films was approximately 15.7 µm. As a result of the temperature coefficient of resistance (TCR = 1/R * dR/dT), the YBCO thick films annealed at 700 °C showed the maximum value of -3.1%/°C and all YBCO thick films showed typical NTCR (negative temperature coefficient of resistance) properties, displaying decreased electrical resistance with an increase in temperature.

  15. Three-dimensional model for aerosol transport and deposition in expanding and contracting alveoli.

    PubMed

    Balásházy, Imre; Hofmann, Werner; Farkas, Arpád; Madas, Balázs G

    2008-04-01

    Particle transport and deposition within a model alveolus, represented by a rhythmically expanding and contracting hemisphere, was modeled by a three-dimensional analytical model for the time-dependent air velocity field as a superposition of uniform and radial flow components, satisfying both the mass and momentum conservation equations. Trajectories of particles entrained in the airflow were calculated by a numerical particle trajectory code to compute simultaneously deposition by inertial impaction, gravitational sedimentation, Brownian diffusion, and interception. Five different orientations of the orifice of the alveolus relative to the direction of gravity were selected. Deposition was calculated for particles from 1 nm to 10 microm, for 3 breathing conditions, and for 5 different entrance times relative to the onset of inspiration. For the analyzed cases, the spatial orientation of the orifice of an alveolus has practically no effect on deposition for particles below about 0.1 microm, where deposition is dominated by Brownian motion. Above about 1 microm, where deposition is governed primarily by gravitational settling, deposition can vary from 0 to 100%, depending on the spatial orientation, while deposition of particles 0.1-1 microm falls between these two extreme cases. Due to the isotropic nature of Brownian motion, deposition of the 10-nm particles is practically uniform for all spatial orientations. However, for larger particles, deposition can be quite inhomogeneous, consistent with the direction of gravity. While nearly all particles are exhaled during the successive expiration phase, there are a few cases where particles still leave the alveolus even after many breathing cycles.

  16. ANALYSIS OF RESPIRATORY DEPOSITION OF INHALED PARTICLES FOR DIFFERENT DOSE METRICS: COMPARISON OF NUMBER, SURFACE AREA AND MASS DOSE OF TYPICAL AMBIENT BI-MODAL AEROSOLS

    EPA Science Inventory

    ANALYSIS OF RESPIRATORY DEPOSITION OF INHALED PARTICLES FOR DIFFERENT DOSE METRICS: COMPARISON OF NUMBER, SURFACE AREA AND MASS DOSE OF TYPICAL AMBIENT BI-MODAL AEROSOLS.
    Chong S. Kim, SC. Hu*, PA Jaques*, US EPA, National Health and Environmental Effects Research Laboratory, ...

  17. High-performance laser mode-locker with glass-hosted SWNTs realized by room-temperature aerosol deposition.

    PubMed

    Kim, Hyung-Jun; Choi, Ho-Jun; Nam, Song-Min; Song, Yong-Won

    2011-02-28

    We preserve optical nonlinear properties of single-walled carbon nanotubes (SWNTs) within SiO2-host employing aerosol deposition (AD) that guarantees the formation of dense ceramic thick films at room temperature without combustion and solubility limitation of the SWNTs. The intact nonlinearity is verified with transmittance check, Raman spectrometry and electron microscopes. As a saturable absorption device, the SiO2-SWNT composite film successfully mode-locks fiber lasers inducing high-quality output pulses with the measured pulse duration and repetition rate of 890 fs and 9.52 MHz, respectively. After experiencing the intracavity power higher than 20 dBm, the hosted SWNTs are survived to function as the pulse formers.

  18. Pharmaceutical aerosols deposition patterns from a Dry Powder Inhaler: Euler Lagrangian prediction and validation.

    PubMed

    Ravi Kannan, Ravishekar; Przekwas, A J; Singh, Narender; Delvadia, Renishkumar; Tian, Geng; Walenga, Ross

    2017-04-01

    This study uses Computational Fluid Dynamics (CFD) to predict, analyze and validate the deposition patterns in a human lung for a Budesonide drug delivered from the Novolizer Dry Powder Inhaler device. We used a test case of known deposition patterns to validate our computational Euler Lagrangian-based deposition predictions. Two different lung models are used: (i) a basic ring-less trachea model and (ii) an advanced Human Zygote5 model. Unlike earlier attempts, the current simulations do not include the device in the computational domain. This greatly reduces the computational effort. To mimic the device, we model the inlet particle jet stream from the device as a spray entering the mouth in a conical fashion. Deposition studies in the various lung regions were performed. We were able to computationally predict and then demonstrate the enhanced deposition in the tracheal and first generation rings/ridges. The enhanced vorticity creation due to the ring structure and the geometrical design contributes to larger deposition in the Zygote5 model. These are in accord with existing data, unlike the ring-less model. Our validated results indicate the need to (i) introduce the ridges in the experimental casts and the CFD surface meshes to be anatomically consistent and obtain physiologically consistent depositions; (ii) introduce a factor to account for the recirculating lighter particles in empirical models.

  19. Aerosol fluxes in the marine boundary layer

    NASA Astrophysics Data System (ADS)

    Petelski, Tomasz; Zieliński, Tymon; Makuch, Przemysław; Kowalczyk, Jakub; Ponczkowska, Agnieszka; Drozdowska, Violetta; Piskozub, Jacek

    2010-05-01

    We present aerosol emission fluxes and concentrations calculated from in-situ measurement in the Nordic Sea from R/V Oceania. We compare vertical fluxes calculated with the eddy correlation and gradient methods. We use the results to test the hypothesis that marine aerosol emitted from the sea surface helps to clear the boundary layer from other aerosol particles. As the emitted droplets do not dry out in the highly humid surface layer air and because of their sizes most of them are deposited quickly at the sea surface. Therefore marine aerosol has many features of rain meaning that the deposition in the marine boundary layer in high wind events is controlled not only by the "dry" processes but also by the "wet" scavenging. We have estimated the effectiveness of the process using our own measurements of vertical aerosol fluxes in the Nordic Seas. This process could explain observed phenomenon of lower Arctic aerosol optical thickness (AOT) when the air masses moved over open sea than over sea-ice. We show a negative correlation between the sea-ice coverage in the seas adjacent to Svalbard and monthly AOT values in Ny Alesund.

  20. HCl in rocket exhaust clouds - Atmospheric dispersion, acid aerosol characteristics, and acid rain deposition

    NASA Technical Reports Server (NTRS)

    Pellett, G. L.; Sebacher, D. I.; Bendura, R. J.; Wornom, D. E.

    1983-01-01

    Both measurements and model calculations of the temporal dispersion of peak HCl (g + aq) concentration in Titan III exhaust clouds are found to be well characterized by one-term power-law decay expressions. The respective coefficients and decay exponents, however, are found to vary widely with meteorology. The HCl (g), HCl (g + aq), dewpoint, and temperature-pressure-altitude data for Titan III exhaust clouds are consistent with accurately calculated HCl/H2O vapor-liquid compositions for a model quasi-equilibrated flat surface aqueous aerosol. Some cloud evolution characteristics are also defined. Rapid and extensive condensation of aqueous acid clearly occurs during the first three min of cloud rise. Condensation is found to be intensified by the initial entrainment of relatively moist ambient air from lower levels, that is, from levels below eventual cloud stabilization. It is pointed out that if subsequent dilution air at stabilization altitude is significantly drier, a state of maximum condensation soon occurs, followed by an aerosol evaporation phase.

  1. Multiscale Airflow Model and Aerosol Deposition in Healthy and Emphysematous Rat Lungs

    NASA Astrophysics Data System (ADS)

    Oakes, Jessica; Marsden, Alison; Grandmont, Celine; Darquenne, Chantal; Vignon-Clementel, Irene

    2012-11-01

    The fate of aerosol particles in healthy and emphysematic lungs is needed to determine the toxic or therapeutic effects of inhalable particles. In this study we used a multiscale numerical model that couples a 0D resistance and capacitance model to 3D airways generated from MR images. Airflow simulations were performed using an in-house 3D finite element solver (SimVascular, simtk.org). Seven simulations were performed; 1 healthy, 1 uniform emphysema and 5 different cases of heterogeneous emphysema. In the heterogeneous emphysema cases the disease was confined to a single lobe. As a post processing step, 1 micron diameter particles were tracked in the flow field using Lagrangian particle tracking. The simulation results showed that the inhaled flow distribution was equal for the healthy and uniform emphysema cases. However, in the heterogeneous emphysema cases the delivery of inhaled air was larger in the diseased lobe. Additionally, there was an increase in delivery of aerosol particles to the diseased lobe. This suggests that as the therapeutic particles would reach the diseased areas of the lung, while toxic particles would increasingly harm the lung. The 3D-0D model described here is the first of its kind to be used to study healthy and emphysematic lungs. NSF Graduate Fellowship (Oakes), Burroughs Wellcome Fund (Marsden, Oakes) 1R21HL087805-02 from NHLBI at NIH, INRIA Team Grant.

  2. Variations in the concentration and isotopic composition of nitrate nitrogen in wet deposition and their relation with meteorological conditions in Xi'an city, Northwest China

    NASA Astrophysics Data System (ADS)

    Xing, M.; Liu, W.

    2012-12-01

    The characterization of N isotopes in NO3- is an effective method to determine NO3- sources and NOX transformation mechanisms. Xi'an city is located in a semi-arid to arid region and is representative of most cities in the north and Northwest of China. Few studies have been carried out on N isotopes in wet deposition of this region. In this study, 29 wet deposition samples were collected from Xi'an city in northwestern China between March 2008 and May 2009 and analyzed for their volume-weighted NO3- and NH4+ concentrations and N isotopic compositions. Volume-weighted mean concentrations were 3.9 μmol L-1 for NO3- and 13.5 μmol L-1 for NH4+. The wet deposition samples showed pronounced seasonal variation in the N isotopic composition of NO3- with δ15N-NO3- ranging from -2.0‰ to +9.2‰ over the course of a year, with a mean value of +2.6 ± 2.6‰. Higher δ15N-NO3- values were observed in the cool season (November-May, +3.8‰) than in the warm season (June-October, +1.0‰). In autumn and winter in particular, the mean δ15N-NO3- values were clearly different (+0.9‰ and +6.7‰, respectively). Various factors are shown to lead to variation in the δ15N-NO3- values in wet deposition. One effect is changing ratios of N derived from agricultural/soil sources (low δ15N-NO3-, dominant in the warm season) and fossil fuel-derived NOX (high δ15N-NO3-, relatively more important in the cool season). However, in the cool season δ15N-NO3- unexpectedly shows a strong negative correlation with SO2 concentration, which should correlate with fossil fuel combustion inputs. This may be explained by interactions of N-species with other atmospheric pollutants. The results also suggest that temperature may be a significant factor affecting δ15N-NO3-. The NOX reacts in different ways depending on temperature, leading to a correlation of δ15N-NO3- with temperature. Moreover, the effects of dilution cannot be neglected here, as there is clear seasonal variation in

  3. Comparison of methods for evaluation of aerosol deposition in the model of human lungs

    NASA Astrophysics Data System (ADS)

    Belka, Miloslav; Lippay, Josef; Lizal, Frantisek; Jedelsky, Jan; Jicha, Miroslav

    2014-03-01

    It seems to be very convenient to receive a medicine by inhalation instead of injection. Unfortunately transport of particles and targeted delivery of a drug in human respiratory airways is very complicated task. Therefore we carried out experiments and tested different methods for evaluation of particle deposition in a model of human lungs. The model included respiratory airways from oral cavity to 7th generation of branching. Particles were dispersed by TSI Small-scale Powder Disperser 3433 and delivered to the model. The model was disassembled into segments after the deposition of the particles and local deposition was measured. Two methods were used to analyse the samples, fluorescence spectroscopy and optical microscopy. The first method was based on measuring the intensity of luminescence, which represented the particle deposition. The second method used the optical microscope with phase-contrast objective. A dispersion of isopropanol and particles was filtrated using a vacuum filtration unit, a filter was placed on glass slide and made transparent. The particles on the filter were counted manually and the deposition was calculated afterwards. The results of the methods were compared and both methods proved to be useful.

  4. Preparation and Characterization of Multilayer Capacitor with SrTiO3 Thin Films by Aerosol Chemical Vapor Deposition

    NASA Astrophysics Data System (ADS)

    Wang, Shuqiang; Kawase, Akihiro; Ogawa, Hirotaka

    2006-09-01

    The deposition of crystalline and amorphous STO (SrTiO3) thin films by aerosol chemical vapor deposition (ASCVD) was investigated. The crystalline STO thin film exhibited a higher dielectric constant of approximately 160 and a dielectric loss (\\tanδ) of 3.5% (at 1 kHz). In contrast, the amorphous STO thin films with dielectric constants of 20-65 showed a smaller dielectric loss below 1% and much lower leakage currents of 10-8-10-6 A/cm2 at up to ± 30 VDC. On the basis of these results, a thin-film multilayer ceramic capacitor (MLCC) with ten amorphous STO dielectric layers and Pt electrodes of 160 and 120 nm thicknesses, respectively, was prepared at a processing temperature of 600 °C, showing a capacitance density of higher than 900 nF/cm2 (effective electrode area: 2× 2 mm2), a dielectric loss of 0.1% at 1 kHz and a leakage current of 10-7 A/cm2 at ± 5 VDC.

  5. Aerosolized droplet mediated self-assembly of photosynthetic pigment analogues and deposition onto substrates.

    PubMed

    Shah, Vivek B; Biswas, Pratim

    2014-02-25

    Self-assembled photosynthetic molecules have a high extinction coefficient and a broad absorption in the infrared region, and these properties can be used to improve the efficiency of solar cells. We have developed a single-step method for the self-assembly of synthetic chlorin molecules (analogues of native bacteriochlorophylls) in aerosolized droplets, containing a single solvent and two solvents, to synthesize biomimetic light-harvesting structures. In the single-solvent approach, assembly is promoted by a concentration-driven process due to evaporation of the solvent. The peak absorbance of Zn(II) 3-(1-hydroxyethyl)-10-phenyl-13(1)-oxophorbine (1) in methanol shifted from 646 nm to 725 nm (∼ 80 nm shift) after assembly, which is comparable to the shift observed in the naturally occurring assembly of bacteriochlorophyll c. Although assembly is thermodynamically favorable, the kinetics of self-assembly play an important role, and this was demonstrated by varying the initial concentration of the pigment monomer. To overcome kinetic limitations, a two-solvent approach using a volatile solvent (tetrahydrofuran) in which the dye is soluble and a less volatile solvent (ethanol) in which the dye is sparingly soluble was demonstrated to be effective. The effect of molecular structure is demonstrated by spraying the sterically hindered Zn(II) 3-(1-hydroxyethyl)-10-mesityl-13(1)-oxophorbine (2), which is an analogue of 1, under similar conditions. The results illustrate a valuable and facile aerosol-based method for the formation of films of supramolecular assemblies.

  6. Influence of dry deposition of semi-volatile organic compounds (VOC) on secondary organic aerosol (SOA) formation in the Mexico City plume

    NASA Astrophysics Data System (ADS)

    Hodzic, Alma; Madronich, Sasha; Aumont, Bernard; Lee-Taylor, Julia; Karl, Thomas

    2013-04-01

    The dry deposition removal of organic compounds from the atmosphere and its impact on organic aerosol mass is currently unexplored and unaccounted for in chemistry-climate models. The main reason for this omission is that current models use simplified SOA mechanisms that lump precursors and their products into volatility bins, therefore losing information on other important properties of individual molecules (or groups) that are needed to calculate dry deposition. In this study, we apply the Generator of Explicit Chemistry and Kinetics of Organics in the Atmosphere (GECKO-A) to simulate SOA formation and estimate the influence of dry deposition of VOCs on SOA concentrations downwind of Mexico City. SOA precursors considered here include short- and long-chain alkanes (C3-25), alkenes, and light aromatics. The results suggest that 90% of SOA produced in Mexico City originates from the oxidation and partitioning of long-chain (C>12) alkanes, while the regionally exported SOA is almost equally produced from long-chain alkanes and from shorter alkanes and light aromatics. We show that dry deposition of oxidized gases is not an efficient sink for SOA, as it removes <5% of SOA within the city's boundary layer and ~15% downwind. We discuss reasons for this limited influence, and investigate separately the impacts on short and long-chain species. We show that the dry deposition is competing with the uptake of gases to the aerosol phase, and because dry deposition of submicron aerosols is slow, condensation onto particles protects organic gases from deposition and therefore increases their atmospheric burden and lifetime. In the absence of this condensation, ~50% of the regionally produced mass would have been dry-deposited.

  7. Particle deposition in airways of chronic respiratory patients exposed to an urban aerosol.

    PubMed

    Horemans, Benjamin; Van Holsbeke, Cedric; Vos, Wim; Darchuk, Larysa; Novakovic, Velibor; Fontan, Angel C; De Backer, Jan; Van Grieken, René; De Backer, Wilfried; De Wael, Karolien

    2012-11-06

    Urban atmospheres in modern cities carry characteristic mixtures of particulate pollution which are potentially aggravating for chronic respiratory patients (CRP). Although air quality surveys can be detailed, the obtained information is not always useful to evaluate human health effects. This paper presents a novel approach to estimate particle deposition rates in airways of CRP, based on real air pollution data. By combining computational fluid dynamics with physical-chemical characteristics of particulate pollution, deposition rates are estimated for particles of different toxicological relevance, that is, minerals, iron oxides, sea salts, ammonium salts, and carbonaceous particles. Also, it enables some qualitative evaluation of the spatial, temporal, and patient specific effects on the particle dose upon exposure to the urban atmosphere. Results show how heavy traffic conditions increases the deposition of anthropogenic particles in the trachea and lungs of respiratory patients (here, +0.28 and +1.5 μg·h(-1), respectively). In addition, local and synoptic meteorological conditions were found to have a strong effect on the overall dose. However, the pathology and age of the patient was found to be more crucial, with highest deposition rates for toxic particles in adults with a mild anomaly, followed by mild asthmatic children and adults with severe respiratory dysfunctions (7, 5, and 3 μg·h(-1), respectively).

  8. Optical properties of aerosols over a tropical rain forest in Xishuangbanna, South Asia

    NASA Astrophysics Data System (ADS)

    Ma, Yongjing; Xin, Jinyuan; Zhang, Wenyu; Wang, Yuesi

    2016-09-01

    Observation and analysis of the optical properties of atmospheric aerosols in a South Asian tropical rain forest showed that the annual mean aerosol optical depth (AOD) and aerosol Ångström exponent (α) at 500 nm were 0.47 ± 0.30 (± value represents the standard deviation) and 1.35 ± 0.32, respectively, from 2012 to 2014, similar with that of Amazon region. Aerosol optical properties in this region varied significantly between the dry and wet seasons. The mean AOD and α were 0.50 ± 0.32 and 1.41 ± 0.28, respectively, in the dry season and 0.41 ± 0.20 and 1.13 ± 0.41 in the wet season. Because of the combustion of the rich biomass in the dry season, fine modal smoke aerosols increased, which led to a higher AOD and smaller aerosol control mode than in the wet season. The average atmospheric humidity in the wet season was 85.50%, higher than the 79.67% during the dry season. In the very damp conditions of the wet season, the aerosol control mode was relatively larger, while AOD appeared to be lower because of the effect of aerosol hygroscopic growth and wet deposition. The trajectories were similar both in dry and wet, but with different effects on the aerosol concentration. The highest AOD values 0.66 ± 0.34 (in dry) and 0.45 ± 0.21 (in wet) both occurred in continental air masses, while smaller (0.38-0.48 in dry and 0.30-0.35 in wet) in oceanic air masses. The range of AOD values during the wet season was relatively narrow (0.30-0.45), but the dry season range was wider (0.38-0.66). For the Ångström exponent, the range in the wet season (0.74-1.34) was much greater than that in the dry season (1.33-1.54).

  9. Geochemical investigation of dry- and wet-deposited dust during the same dust-storm event in Harbin, China: Constraint on provenance and implications for formation of aeolian loess

    NASA Astrophysics Data System (ADS)

    Xie, Yuanyun; Chi, Yunping

    2016-04-01

    A strong dust-storm event occurred in Harbin, China on May 11, 2011. The dry- and wet-deposited dust depositions in this dust-storm event, together with the surface sediments from the potential sources, were collected to study grain size distributions, carbonate content and carbon isotopic composition of carbonate, major element, trace element and rare earth elements (REE), and Sr-Nd isotopic compositions. The results indicate as follows. The dry-deposited dusts are characterized by bimodal grain-size distributions with a fine mode at 3.6 μm and a coarse mode at 28 μm whereas the wet-deposited dusts are indicative of unimodal grain-size modes with a fine mode at 6 μm. The dust-storm depositions are influenced to a certain extent by sedimentary sorting and are of a derivation from the recycled sediments. Based on identifying the immobility of element pairs before constraining sources of dust-storm deposits using geochemical elements, in conjunction with REE and especially Sr-Nd isotopic compositions, the primary and strengthening sources for the dust-storm event were detected, respectively. The Hunsandake Sandy Land as the primary source and the Horqin Sandy Land as the strengthening source were together responsible for the derivation of dust depositions during dust-storm event. The Hunsandake Sandy Land, however, contributes less dust to the dust-storm event in Harbin compared to the Horqin Sandy Land, and the Hulun Buir Sandy Land is undoubtedly excluded from being one of the sources for dust-storm depositions in Harbin. There are not notable differences in geochemical (especially Sr-Nd isotopic) compositions between dry- and wet-deposited dusts, indicating that the wet-deposited dust is of identical derivation to the dry-deposited dust. Based on our observations, it is of interest to suggest that fine and coarse particles in the CLP (Chinese Loess Plateau) loess possibly have the same sources.

  10. Attributes for NHDPlus Catchments (Version 1.1) for the Conterminous United States: Average Atmospheric (Wet) Deposition of Inorganic Nitrogen, 2002

    USGS Publications Warehouse

    Wieczorek, Michael; LaMotte, Andrew E.

    2010-01-01

    This data set represents the average atmospheric (wet) deposition, in kilograms per square kilometer, of inorganic nitrogen for the year 2002 compiled for every catchment of NHDPlus for the conterminous United States. The source data set for wet deposition was from the USGS's raster data set atmospheric (wet) deposition of inorganic nitrogen for 2002 (Gronberg, 2005). The NHDPlus Version 1.1 is an integrated suite of application-ready geospatial datasets that incorporates many of the best features of the National Hydrography Dataset (NHD) and the National Elevation Dataset (NED). The NHDPlus includes a stream network (based on the 1:100,00-scale NHD), improved networking, naming, and value-added attributes (VAAs). NHDPlus also includes elevation-derived catchments (drainage areas) produced using a drainage enforcement technique first widely used in New England, and thus referred to as "the New England Method." This technique involves "burning in" the 1:100,000-scale NHD and when available building "walls" using the National Watershed Boundary Dataset (WBD). The resulting modified digital elevation model (HydroDEM) is used to produce hydrologic derivatives that agree with the NHD and WBD. Over the past two years (2007-2008), an interdisciplinary team from the U.S. Geological Survey (USGS), and the U.S. Environmental Protection Agency (USEPA), and contractors, found that this method produces the best quality NHD catchments using an automated process (USEPA, 2007). The NHDPlus dataset is organized by 18 Production Units that cover the conterminous United States. The NHDPlus version 1.1 data are grouped by the U.S. Geologic Survey's Major River Basins (MRBs, Crawford and others, 2006). MRB1, covering the New England and Mid-Atlantic River basins, contains NHDPlus Production Units 1 and 2. MRB2, covering the South Atlantic-Gulf and Tennessee River basins, contains NHDPlus Production Units 3 and 6. MRB3, covering the Great Lakes, Ohio, Upper Mississippi, and Souris

  11. Seasonal and rainfall-type variations in inorganic ions and dicarboxylic acids and acidity of wet deposition samples collected from subtropical East Asia

    NASA Astrophysics Data System (ADS)

    Tsai, Ying I.; Hsieh, Li-Ying; Kuo, Su-Ching; Chen, Chien-Lung; Wu, Pei-Ling

    2011-07-01

    Rainfall samples were collected over a period of 3 years and 8 months in subtropical East Asia. They are categorized into different rainfall types and analyzed to assess the ionic composition and its effect on the acidity of wet deposition in southern Taiwan. Only 4% of samples had a pH of <5.0, indicating that the study area is not impacted significantly by acid rain. The volume-weighted mean (VWM) pH by rainfall type was Spring Rain 5.74, Typhoon Rain 5.56, Summer Rain 5.46, Typhoon Outer Circulation (TOC) Rain 5.45, Plum Rain 5.32 and Autumn-Winter Rain 5.29. Dilution effects were important to the equivalent ionic concentration of different rainfall types. HCO 3-, SO 42- and Cl - were detected as major anions whereas NH 4+, Na + and Ca 2+ were major cations. CO 2-derived HCO 3- was the major ionic species in all but Typhoon Rain and Spring Rain, in which the major species were Na + and Cl - and Ca 2+, respectively. Excluding HCO 3-, the major species were NH 4+, Na + and Ca 2+ in Plum Rain, the secondary photochemical products SO 42-, NO 3- and NH 4+ in TOC Rain and Summer Rain, and Na + and Ca 2+ in Autumn-Winter Rain. Calculation of arithmetic means showed that dicarboxylic acids contributed between 0.25% and 0.53% of the total ionic concentration and of these, oxalic acid contributed the least (81.3% of the dicarboxylic acid) to TOC Rain and the most (96.1% of the dicarboxylic acid) to Spring Rain, suggestive of long-range transport in the latter. Differences in wet deposition composition were shown to be a result of differences in local emissions and long-range transport (hence of prevailing wind direction) during the period of rainfall and of the frequency and volume of rain that typifies each rainfall type. Principal component analysis (PCA) further revealed that traffic-related and industrial organic and inorganic pollutants, their secondary photochemical products, sea salts, and dust are important contributors to wet deposition. Moreover, the ratio of

  12. Aerosol Characterization and New Instrumentation for Better Understanding Snow Radiative Properties

    NASA Astrophysics Data System (ADS)

    Beres, N. D.

    2015-12-01

    Snow albedo is determined by snowpack thickness and grain size, but also affected by contamination with light-absorbing, microscopic (e.g., mineral dust, combustion aerosols, bio-aerosols) and macroscopic (e.g., microalgae, plant debris, sand, organisms) compounds. Most currently available instruments for measuring snow albedo utilize the natural, downward flux of solar radiation and the reflected upward flux. This reliance on solar radiation (and, thus, large zenith angles and clear-sky conditions) leads to severe constraints, preventing characterization of detailed diurnal snow albedo cycles. Here, we describe instrumentation and methodologies to address these limitations with the development and deployment of new snow radiation sensors for measuring surface spectral and in-snow radiative properties. This novel instrumentation will be tested at the CRREL/UCSB Eastern Sierra (CUES) Snow Study Site at Mammoth Mountain, which is extensively instrumented for characterizing snow properties including snow albedo and surface morphology. However, it has been lacking instrumentation for the characterization of aerosols that can be deposited on the snow surface through dry and wet deposition. Currently, we are installing aerosol instrumentation at the CUES site, which are also described. This includes instruments for the multi-wavelength measurement of aerosol scattering and absorption coefficients and for the characterization of aerosol size distribution. Knowledge of aerosol concentration and physical and optical properties will allow for the study of aerosol deposition and modification of snow albedo and for establishing an aerosol climatology for the CUES site.

  13. Dispersion of aerosol particles in the atmosphere: Fukushima

    NASA Astrophysics Data System (ADS)

    Haszpra, Tímea; Lagzi, István; Tél, Tamás

    2013-04-01

    Investigation of dispersion and deposition of aerosol particles in the atmosphere is an essential issue, because they have an effect on the biosphere and atmosphere. Moreover, aerosol particles have different transport properties and chemical and physical transformations in the atmosphere compared to gas phase air pollutants. The motion of a particle is described by a set of ordinary differential equations. The large-scale dynamics in the horizontal direction can be described by the equations of passive scalar advection, but in the vertical direction a well-defined terminal velocity should be taken into account as a term added to the vertical wind component. In the planetary boundary layer turbulent diffusion has an important role in the particle dispersion, which is taken into account by adding stochastic terms to the deterministic equations above. Wet deposition is also an essential process in the lower levels of the atmosphere, however, its precise parameterization is a challenge. For the simulations the wind field and other necessary data were taken from the ECMWF ERA-Interim database. In the case of the Fukushima Daiichi nuclear disaster (March-April 2011) radioactive aerosol particles were also released in the planetary boundary layer. Simulations (included the continuous and varying emission from the nuclear power plant) will be presented for the period of 14-23 March. Results show that wet deposition also has to be taken into consideration in the lower levels of the atmosphere. Furthermore, dynamical system characteristics are evaluated for the aerosol particle dynamics. The escape rate of particles was estimated both with and without turbulent diffusion, and in both cases when there was no wet deposition and also when wet deposition was taken into consideration.

  14. [Aerosol deposition and clinical performance verified with a spacer device made in Brazil

    PubMed

    Camargos, P A; Rubim, J A; Simal, C J; Lasmar, L M

    2000-01-01

    OBJECTIVE: To assess the lung deposition pattern of radioaerosol and the clinical performance of a spacer developed and made in Brazil. METHODS: Qualitative - in a patient with cystic fibrosis - and semi-quantitative - in two healthy volunteers - assessment of pulmonary deposition of (99)mtechnetium was done using the Aerogama Medical oxigen driven nebulizer system attached to the spacer and a gama-camera (Siemens, model Orbiter) connected to a microcomputer. In the next step, clinical assessment was carried out in 50 asthmatic children, aged from four months to 13 years old with an acute attack, using conventional doses of albuterol through a metered dose inhaler attached to the spacer device. RESULTS: Qualitative assessment revealed a lung silhouette comparable with those obtained in the inhalation scintigraphy and semiquantitative assessment reveals that 7.5% to 8.0% of the inhaled (99m)technetium reached the volunteerś lungs. Statistically significant differences (p < 0.001) were observed comparing clinical scores at admission with those verified 20 and 40 minutes after albuterol inhalation; conversely, no significance was obtained for scores taken at 60 and 80 minutes. CONCLUSIONS: Although we used an alternative method, the scintigraphic assessment reveals an expected pattern of pulmonary deposition. Similarly, clinical performance in the treatment of an acute attack showed results comparable with those obtained with other spacers devices.

  15. Aerosolized liposomal amphotericin B: prediction of lung deposition, in vitro uptake and cytotoxicity.

    PubMed

    Fauvel, Mélanie; Farrugia, Cécile; Tsapis, Nicolas; Gueutin, Claire; Cabaret, Odile; Bories, Christian; Bretagne, Stéphane; Barratt, Gillian

    2012-10-15

    To predict the efficacy and toxicity of pulmonary administration of liposomal amphotericin B (L-AMB) for the treatment or the prevention of pulmonary invasive aspergillosis, a multistage liquid impinger was used to estimate the concentrations of drug that could be attained in different lung compartments after nebulization. The highest concentration of amphotericin B was found in the alveolar compartment, where it was calculated that the concentration in the lung surfactant could reach 54 μM or more when 21.6 μmoles of drug as liposomes was nebulized. The uptake and toxicity of L-AMB were studied in vitro using the A549 human lung epithelial cell line. Uptake was time and concentration-dependent and reached intracellular concentrations exceeding the minimal inhibitory concentrations for most Aspergillus species. The toxicity of L-AMB toward these cells, estimated by the MTT reduction assay, was reduced compared with the conventional form, deoxycholate amphotericin B (D-AMB), with an IC(50) value of about 120 μM after 24 h of exposure for D-AMB, but only a 13% reduction in viability for 200 μM L-AMB at 24 h. These results indicate that aerosol therapy with nebulized L-AMB could be efficient but that doses need to be carefully controlled to avoid toxicity.

  16. A 10-year global gridded Aerosol Optical Thickness Reanalysis for climate and applied applications

    NASA Astrophysics Data System (ADS)

    Lynch, P.; Reid, J. S.; Zhang, J.; Westphal, D. L.; Campbell, J. R.; Curtis, C. A.; Hegg, D.; Hyer, E. J.; Sessions, W.; Shi, Y.; Turk, J.

    2013-12-01

    While standalone satellite and model aerosol products see wide utilization, there is a significant need of a best-available fused product on a regular grid for numerous climate and applied applications. Remote sensing and modeling technologies have now advanced to a point where aerosol data assimilation is an operational reality at numerous centers. It is inevitable that, like meteorological reanalyses, aerosol reanalyses will see heavy use in the near future. A first long term, 2003-2012 global 1x1 degree and 6-hourly aerosol optical thickness (AOT) reanalysis product has been generated. The goal of this effort is not only for climate applications, but to generate a dataset that can be used by the US Navy to understand operationally hindering aerosol events, aerosol impacts on numerical weather prediction, and application of electro-optical technologies. The reanalysis utilizes Navy Aerosol Analysis and Prediction System (NAAPS) at its core and assimilates quality controlled collection 5 Moderate Resolution Imaging Spectroradiometer (MODIS) AOD with minor corrections from Multi-angle Imaging SpectroRaditometer (MISR). A subset of this product includes Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) lidar assimilation since its launch in mid-2006. Surface aerosol sources, including dust and smoke, in the aerosol model have been regionally tuned so that fine and coarse mode AOTs best match those resolve by ground-based Aerosol Robotic Network (AERONET). The AOT difference between the model and satellite AOT is then used to adjust other aerosol processes, eg., sources, dry deposition, etc. Aerosol wet deposition is constrained with satellite-retrieved precipitation. The final AOT reanalysis is shown to exhibit good agreement with AERONET. Here we review the development of the reanalysis and consider issues particular to aerosol reanalyses that make them distinct from standard meteorological reanalyses. Considerations are also made for extending such work

  17. Corrosion Behavior of Ti60 Alloy under a Solid NaCl Deposit in Wet Oxygen Flow at 600 °C

    PubMed Central

    Fan, Lei; Liu, Li; Yu, Zhongfen; Cao, Min; Li, Ying; Wang, Fuhui

    2016-01-01

    The corrosion behavior of Ti60 alloy covered with a solid NaCl deposit in wet oxygen flow at 600 °C has been studied further by SEM, EDX, XPS, XRD, TEM and EPMA analysis. The results show that solid NaCl and H2O react with Ti oxides, which destroyed the Ti oxide scale to yield the non-protective Na4Ti5O12 and other volatile species. The resulting corrosion product scale was multilayered and contained abundant rapid diffusion channels leading to the fast diffusion which improved the corrosion rate. A possible mechanism has been proposed for the NaCl-covered Ti60 alloy, based on the experimental results. PMID:27357732

  18. Effects of below-cloud scavenging on the regional aerosol budget in East Asia

    NASA Astrophysics Data System (ADS)

    Bae, Soo Ya; Park, Rokjin J.; Kim, Yong Pyo; Woo, Jung-Hun

    2012-10-01

    We examine the effects of below-cloud scavenging on regional aerosol simulations over East Asia using wet deposition fluxes observed at Acid Deposition Monitoring Network in East Asia (EANET) sites and the Community Multiscale Air Quality (CMAQ) model together with a new below-cloud-scavenging scheme. Typical air quality models, including CMAQ, assume below-cloud scavenging as a simple first-order process with a constant or simple form depending on rain intensity. The scheme used here accounts for the collection efficiency, terminal velocity of raindrops, raindrop-size distributions, and particle-size distributions, which are important factors affecting below-cloud scavenging. We conduct model simulations for spring 2001, including baseline and sensitivity simulations. Our analysis mainly focuses on May 2001 to rule out the effect of dust aerosols. Simulated wet deposition fluxes of SO42-, NO3-, and NH4+ by the new scheme are increased by 103, 16, and 108%, respectively, relative to the baseline simulation and show better agreement with observations. The effect of below-cloud scavenging on coarse particles is even greater, producing wet deposition fluxes two orders of magnitude higher than the baseline. The resulting changes in the model indicate the considerable impacts of below-cloud scavenging on regional aerosol simulations over East Asia, where both anthropogenic emissions and natural sources of aerosols are present throughout the year. An accurate wet scavenging simulation is critical to simulate the atmospheric burden and wet deposition fluxes of both fine-mode and coarse-mode aerosols over East Asia.

  19. Washout/rainout contribution in wet deposition estimated by 0.5 mm precipitation sampling/analysis

    NASA Astrophysics Data System (ADS)

    Aikawa, Masahide; Hiraki, Takatoshi

    A precipitation dataset collected on a 0.5 mm precipitation basis was studied. The parameters analyzed in this study were the pH (i.e., H + concentration), electric conductivity (EC), and SO42- and NO3- concentrations. The NO3- concentration clearly decayed with an increase of the precipitation amount, while a larger variation was observed in the SO42- concentration even when the precipitation amount increased. Assuming that the decaying NO3- concentration (0.70 μg ml -1) was the result of the rainout process, the estimates were: annual total deposition, 3252 mg m -2 yr -1; rainout process, 1092 mg m -2 yr -1; and rainout/total, 34%. The estimates for SO42- were: annual total deposition, 4687 mg m -2 yr -1; rainout process, 2096 mg m -2 yr -1; and rainout/total, 45%.

  20. Wet deposition of pesticides and nitrophenols at two sites in Denmark: measurements and contributions from regional sources.

    PubMed

    Asman, Willem A H; Jørgensen, Andreas; Bossi, Rossana; Vejrup, Karl V; Mogensen, Betty Bügel; Glasius, Marianne

    2005-05-01

    The concentrations of selected pesticides, of some of their degradation products and nitrophenols in rain were measured at two stations in Denmark in the period January 2000-July 2001. Forty compounds were quantified at least at one station during at least one sampling period. Additionally 17 compounds could be detected but not quantified, and 22 compounds could not be detected at all. The highest depositions of pesticides were observed for pendimethalin and desethylterbuthylazine, which is a degradation product of terbuthylazine. The deposition of the nitrophenols 2,4-dinitrophenol, DNOC, 3-methyl-4-nitrophenol was much higher than that of pesticides. The deposition of 2,4-dinitrophenol was e.g. up to a factor of 40 higher than that of pendimethalin. Atrazine, chloridazon, 2,4-D, dieldrin, disulfoton, fenitrothion, isoproturon, lenacil, metazachlor and propachlor were found in precipitation, although these pesticides are not allowed in Denmark. It can therefore be concluded that they came from abroad and have been transported over at least 60-80 km. For some of these compounds the transport distance is much longer.

  1. Weather-dependent change of cesium, strontium, barium and tellurium contamination deposited as aerosols on various cultures.

    PubMed

    Madoz-Escande, C; Santucci, P

    2005-01-01

    Various types of plants (wheat, bean, lettuce, radish and grass) were contaminated by dry deposition of radioactive aerosols ((137)Cs, (85)Sr, (133)Ba and (123 m)Te) in order to supplement the radio-ecological data necessary for operational post-accidental codes. A few days after deposition, rainfalls were applied to these cultures to evaluate the influence of some characteristics of the rain on the contamination of the culture over time. On the other hand, for wheat and bean, the influence of the humidity condition of the foliage at the contamination time was considered. For a given plant species at a given vegetative stage, the four radionuclides were intercepted in an identical way. The interception varied from 30% for bean (young sprout) to 80% for lettuce (near maturity). The global transfer factor values were dependent on both the radionuclides and the plant species; nevertheless, a higher value was obtained for cesium, regardless of the plant and the rainfall (from 0.006 m(2)kg(fresh)(-1) for wheat-grains - contaminated at the shooting stage - or for bean-pods - contaminated at the pre-flowering stage - to 0.1m(2)kg(fresh)(-1) for a whole lettuce). The analysis of the results allowed us on the one hand, to extract parameter values of the foliar transfer directly usable in operational codes, in particular those relating to barium and tellurium, unknown until then, and on the other hand, to lay the foundations of a future, more mechanistic model, taking into account the foliar processes in a finer way.

  2. Structural, mechanical, electrical and wetting properties of ZrNx films deposited by Ar/N2 vacuum arc discharge: Effect of nitrogen partial pressure

    NASA Astrophysics Data System (ADS)

    Abdallah, B.; Naddaf, M.; A-Kharroub, M.

    2013-03-01

    Non-stiochiometric zirconium nitride (ZrNx) thin films have been deposited on silicon substrates by vacuum arc discharge of (N2 + Ar) gas mixtures at different N2 partial pressure ratio. The microstructure, mechanical, electrical and wetting properties of these films are studied by means of X-ray diffraction (XRD), micro-Raman spectroscopy, Rutherford back scattering (RBS) technique, conventional micro-hardness testing, electrical resistivity, atomic force microscopy (AFM) and contact angle (CA) measurements. RBS results and analysis show that the (N/Zr) ratio in the film increases with increasing the N2 partial pressure. A ZrNx film with (Zr/N) ratio in the vicinity of stoichiometric ZrN is obtained at N2 partial pressure of 10%. XRD and Raman results indicate that all deposited films have strained cubic crystal phase of ZrN, regardless of the N2 partial pressure. On increasing the N2 partial pressure, the relative intensity of (1 1 1) orientation with respect to (2 0 0) orientation is seen to decrease. The effect of N2 partial pressure on micro-hardness and the resistivity of the deposited film is revealed and correlated to the alteration of grain size, crystallographic texture, stoichiometry and residual stress developed in the film. In particular, it is found that residual stress and nitrogen incorporation in the film play crucial role in the alteration of micro-hardness and resistivity respectively. In addition, CA and AFM results demonstrate that as N2 partial pressure increases, both the surface hydrophobicity and roughness of the deposited film increase, leading to a significant decrease in the film surface free energy (SFE).

  3. Computational analysis of non-spherical particle transport and deposition in shear flow with application to lung aerosol dynamics--a review.

    PubMed

    Kleinstreuer, Clement; Feng, Yu

    2013-02-01

    All naturally occurring and most man-made solid particles are nonspherical. Examples include air-pollutants in the nano- to micro-meter range as well as blood constituents, drug particles, and industrial fluid-particle streams. Focusing on the modeling and simulation of inhaled aerosols, theories for both spherical and nonspherical particles are reviewed to analyze the contrasting transport and deposition phenomena of spheres and equivalent spheres versus ellipsoids and fibers.

  4. Tungsten Doped TiO2 with Enhanced Photocatalytic and Optoelectrical Properties via Aerosol Assisted Chemical Vapor Deposition

    PubMed Central

    Sathasivam, Sanjayan; Bhachu, Davinder S.; Lu, Yao; Chadwick, Nicholas; Althabaiti, Shaeel A.; Alyoubi, Abdulrahman O.; Basahel, Sulaiman N.; Carmalt, Claire J.; Parkin, Ivan P.

    2015-01-01

    Tungsten doped titanium dioxide films with both transparent conducting oxide (TCO) and photocatalytic properties were produced via aerosol-assisted chemical vapor deposition of titanium ethoxide and dopant concentrations of tungsten ethoxide at 500 °C from a toluene solution. The films were anatase TiO2, with good n-type electrical conductivities as determined via Hall effect measurements. The film doped with 2.25 at.% W showed the lowest resistivity at 0.034 Ω.cm and respectable charge carrier mobility (14.9 cm3/V.s) and concentration (×1019 cm−3). XPS indicated the presence of both W6+ and W4+ in the TiO2 matrix, with the substitutional doping of W4+ inducing an expansion of the anatase unit cell as determined by XRD. The films also showed good photocatalytic activity under UV-light illumination, with degradation of resazurin redox dye at a higher rate than with undoped TiO2. PMID:26042724

  5. Tungsten Doped TiO2 with Enhanced Photocatalytic and Optoelectrical Properties via Aerosol Assisted Chemical Vapor Deposition

    NASA Astrophysics Data System (ADS)

    Sathasivam, Sanjayan; Bhachu, Davinder S.; Lu, Yao; Chadwick, Nicholas; Althabaiti, Shaeel A.; Alyoubi, Abdulrahman O.; Basahel, Sulaiman N.; Carmalt, Claire J.; Parkin, Ivan P.

    2015-06-01

    Tungsten doped titanium dioxide films with both transparent conducting oxide (TCO) and photocatalytic properties were produced via aerosol-assisted chemical vapor deposition of titanium ethoxide and dopant concentrations of tungsten ethoxide at 500 °C from a toluene solution. The films were anatase TiO2, with good n-type electrical conductivities as determined via Hall effect measurements. The film doped with 2.25 at.% W showed the lowest resistivity at 0.034 Ω.cm and respectable charge carrier mobility (14.9 cm3/V.s) and concentration (×1019 cm-3). XPS indicated the presence of both W6+ and W4+ in the TiO2 matrix, with the substitutional doping of W4+ inducing an expansion of the anatase unit cell as determined by XRD. The films also showed good photocatalytic activity under UV-light illumination, with degradation of resazurin redox dye at a higher rate than with undoped TiO2.

  6. Glass-Like Thermal Conductivity of (010)-Textured Lanthanum-Doped Strontium Niobate Synthesized with Wet Chemical Deposition

    DOE PAGES

    Foley, Brian M.; Brown-Shaklee, Harlan J.; Campion, Michael J.; ...

    2014-11-08

    We have measured the cross-plane thermal conductivity (κ) of (010)-textured, undoped, and lanthanum-doped strontium niobate (Sr2-xLaxNb2O7-δ) thin films via time-domain thermoreflectance. Then the thin films were deposited on (001)-oriented SrTiO3 substrates via the highly-scalable technique of chemical solution deposition. We find that both film thickness and lanthanum doping have little effect on κ, suggesting that there is a more dominant phonon scattering mechanism present in the system; namely the weak interlayer-bonding along the b-axis in the Sr2Nb2O7 parent structure. We also compare our experimental results with two variations of the minimum-limit model for κ and discuss the nature of transportmore » in material systems with weakly-bonded layers. The low cross-plane κ of these scalably-fabricated films is comparable to that of similarly layered niobate structures grown epitaxially.« less

  7. Glass-Like Thermal Conductivity of (010)-Textured Lanthanum-Doped Strontium Niobate Synthesized with Wet Chemical Deposition

    SciTech Connect

    Foley, Brian M.; Brown-Shaklee, Harlan J.; Campion, Michael J.; Medlin, Douglas L.; Clem, Paul G.; Ihlefeld, Jon F.; Hopkins, Patrick E.

    2014-11-08

    We have measured the cross-plane thermal conductivity (κ) of (010)-textured, undoped, and lanthanum-doped strontium niobate (Sr2-xLaxNb2O7-δ) thin films via time-domain thermoreflectance. Then the thin films were deposited on (001)-oriented SrTiO3 substrates via the highly-scalable technique of chemical solution deposition. We find that both film thickness and lanthanum doping have little effect on κ, suggesting that there is a more dominant phonon scattering mechanism present in the system; namely the weak interlayer-bonding along the b-axis in the Sr2Nb2O7 parent structure. We also compare our experimental results with two variations of the minimum-limit model for κ and discuss the nature of transport in material systems with weakly-bonded layers. The low cross-plane κ of these scalably-fabricated films is comparable to that of similarly layered niobate structures grown epitaxially.

  8. Preliminary Results from an Assimilation of TOMS Aerosol Observations Into the GOCART Model

    NASA Technical Reports Server (NTRS)

    daSilva, Arlindo; Weaver, Clark J.; Ginoux, Paul; Torres, Omar; Einaudi, Franco (Technical Monitor)

    2000-01-01

    At NASA Goddard we are developing a global aerosol data assimilation system that combines advances in remote sensing and modeling of atmospheric aerosols. The goal is to provide high resolution, 3-D aerosol distributions to the research community. Our first step is to develop a simple assimilation system for Saharan mineral aerosol. The Goddard Chemistry and Aerosol Radiation model (GOCART) provides accurate 3-D mineral aerosol size distributions that compare well with TOMS satellite observations. Surface, mobilization, wet and dry deposition, convective and long-range transport are all driven by assimilated fields from the Goddard Earth Observing System Data Assimilation System, GEOS-DAS. Our version of GOCART transports sizes from.08-10 microns and only simulates Saharan dust. TOMS radiance observations in the ultra violet provide information on the mineral and carbonaceous aerosol fields. We use two main observables in this study: the TOMS aerosol index (AI) which is directly related to the ratio of the 340 and 380 radiances and the 380 radiance. These are sensitive to the aerosol optical thickness, the single scattering albedo and the height of the aerosol layer. The Goddard Aerosol Assimilation System (GAAS) uses the Data Assimilation Office's Physical-space Statistical Analysis System (PSAS) to combine TOMS observations and GOCART model first guess fields. At this initial phase we only assimilate observations into the the GOCART model over regions of Africa and the Atlantic where mineral aerosols dominant and carbonaceous aerosols are minimal, Our preliminary results during summer show that the assimilation with TOMS data modifies both the aerosol mass loading and the single scattering albedo. Assimilated aerosol fields will be compared with assimilated aerosol fields from GOCART and AERONET observations over Cape Verde.

  9. Coal Ash Aerosol in East Asian Outflow as a Source for Oceanic Deposition of Iron and Other Metals

    NASA Astrophysics Data System (ADS)

    Anderson, J. R.; Hua, X.

    2008-12-01

    While ocean deposition of East Asian dust is given significant emphasis as a source of biologically-active trace elements, iron in particular, dust events are episodic and highly seasonal. There is, however, a constant source of aerosol that is chemically similar to dust (albeit amorphous in structure rather than crystalline) in the ash particles emitted from many hundreds of coal-fired power plants that are sited along the entire coastal region of China and Korea. The emission controls on these facilities vary widely and, in even cases of state-of-the-art emission controls, the secondary release of ash can be significant. There are of course even more small industrial and household sources of coal combustion emissions, in most cases with little or no emissions controls. Ash from a modern coal-fired power facility in Korea has been examined chemically and morphologically with electron microscopic techniques. As is characteristic of all such facilities, two principal types of ash are present: (1) flyash, silicate glass spheres that are emitted with the smoke and removed by electrostatic precipitators; and (2) bottom ash, "clinkers" and noncombustible material sticking to the furnace walls that are mixed with water and ground after cooling, then removed as a slurry to a dumping area. In addition, iron sulfide (pyrite) is a common constituent of coal and provides both a source of sulfur dioxide gas and also molten iron spherical particles in the ash. The iron spheres then are rapidly oxidized upon cooling. Bottom ash is a more complex material than flyash in that it contains more iron and other trace metals, plus it contains varying amounts of uncombusted carbon. The post-combustion handling of bottom ash can lead to significant emissions despite the fact that little or none goes out the stack. The iron oxide spheres can also be emitted by this secondary method. The concentrations of ash can be very high in close proximity to power plants (PM10 of several hundred

  10. Spatial and temporal variability of (7)Be and (210)Pb wet deposition during four successive monsoon storms in a catchment of northern Laos.

    PubMed

    Gourdin, E; Evrard, O; Huon, S; Reyss, J-L; Ribolzi, O; Bariac, T; Sengtaheuanghoung, O; Ayrault, S

    2014-10-01

    Fallout radionuclides (7)Be and (210)Pb have been identified as potentially relevant temporal tracers for studying soil particles dynamics (surface vs. subsurface sources contribution; remobilization of in-channel sediment) during erosive events in river catchments. An increasing number of studies compared (7)Be: (210)Pb activity ratio in rainwater and sediment to estimate percentages of freshly eroded particles. However, the lack of data regarding the spatial and temporal variability of radionuclide wet deposition during individual storms has been identified as one of the main gaps in these estimates. In order to determine these key parameters, rainwater samples were collected at three stations during four storms that occurred at the beginning of the monsoon (June 2013) in the Houay Xon mountainous catchment in northern Laos. Rainwater (7)Be and (210)Pb activities measured using very low background hyperpure Germanium detectors ranged from 0.05 to 1.72 Bq L(-1) and 0.02 to 0.26 Bq L(-1), respectively. Water δ(18)O were determined on the same samples. Total rainfall amount of the four sampled storms ranged from 4.8 to 26.4 mm (51 mm in total) at the time-fractionated collection point. Corresponding cumulative (7)Be and (210)Pb wet depositions during the sampling period were 17.6 and 2.9 Bq m(-2), respectively. The (7)Be: (210)Pb activity ratio varied (1) in space from 6 to 9 for daily deposition and (2) in time from 3 to 12 for samples successively collected. Intra-event evolution of rainwater (7)Be and (210)Pb activities as well as δ(18)O highlighted the progressive depletion of local infra-cloud atmosphere radionuclide stock with time (washout), which remains consistent with a Raleigh-type distillation process for water vapour. Intra-storm ratio increasing with time showed the increasing contribution of rainout scavenging. Implications of such variability for soil particle labelling and erosion studies are briefly discussed and recommendations are formulated

  11. [Platanus orientalis foliar N% and delta15 N responses to nitrogen of atmospheric wet deposition in urban area].

    PubMed

    Wang, Yan-Li; Xiao, Hua-Yun; Xiao, Hong-Wei

    2012-04-01

    Leaves of Platanus orientalis were collected since Mar. 2009 till Apr. 2010, in an urban area at Guiyang. After mass of experiments and analysis, we carried out constructing the temporal variation of foliar N% and delta15 N: both higher in Spring/Summer, lower in Autumn, no data of Winter because of leaf abscission. Results showed that foliar N% varied from 1.48% to 5.27%, with an annual average of 3.36%, while the average concentration of total N in rhizospheric soil was 0.29%. The foliar N% rose and fell relative to DIN in rainwater (range from 0.57 mg x L(-1) to 6.74 mg x L(-1)), indicating that the N% content in foliar tissue of plant was approximately proportional to atmospheric N inputs. The range of foliar delta15N were from 4.48 per thousand to 8.39 per thousand, with the average of 6.33 per thousand, much higher than the delta15N-NH4+ of rain water (-19.76 per thousand(-) -10.41 per thousand) and delta15TN of rhizospheric soil (3.19 per thousand +/- 1.04 per thousand). Besides, a good uniform correlation between foliar delta15N and delta15N-NH4+ of rain water were found. As synthesis of two main N sources, the more positive delta15N values of Platanus orientalis can be explained by isotopic fractionation during N uptake and basipetal translocation. These responses of both foliar N% and delta15N to atmospheric nitrogen deposition, revealed the potential value in using vascular leaves as bio-monitors for assessment of N deposition, furthermore, for prevention and control of air pollution in urban ecosystem.

  12. Does the Madden-Julian Oscillation Influence Aerosol Variability?

    NASA Astrophysics Data System (ADS)

    Tian, B.; Waliser, D. E.; Kahn, R. A.; Li, Q.; Yung, Y. L.; Tyranowski, T.; Geogdzhayev, I. V.; Mishchenko, M. I.; Torres, O.; Smirnov, A.

    2007-12-01

    We investigate the modulation of aerosols by the Madden-Julian Oscillation (MJO) using satellite-based global aerosol products, including aerosol index (AI) from the Total Ozone Mapping Spectrometer (TOMS) on Nimbus-7, and aerosol optical thickness (AOT) from the Moderate Resolution Imaging Spectroradiometer (MODIS) on Terra and Aqua and the Advanced Very High Resolution Radiometer (AVHRR) on NOAA satellites. A composite analysis is performed for boreal winter, and the global pentad rainfall data from the NOAA Climate Prediction Center (CPC) Merged Analysis of Precipitation (CMAP) are used to identify MJO events. The MJO composites exhibit large variations in the TOMS AI and MODIS/AVHRR AOT over the equatorial Indian and western Pacific Oceans where MJO convection is active, as well as the tropical Africa and Atlantic Ocean where MJO convection is relatively weak but the background aerosol level is relatively high. A strong inverse linear relationship between the TOMS AI and rainfall anomalies, but a weaker, less coherent positive correlation between the MODIS/AVHRR AOT and rainfall anomalies, were found. The Aerosol Robotic Network AOT pattern at Kaashidoo (73.5°E, 4.9°N) and Nauru (167°E, 0.5°S) is more consistent with MODIS and AVHRR. These results indicate a connection between the MJO, its associated rainfall and circulation variability, and the observed aerosol variations. Several physical and non-physical factors that may contribute to the observed aerosol-rainfall relationship, such as aerosol humidification effect, wet deposition, surface wind speed, phytoplankton, different sensor sensitivities (absorbing versus non-absorbing aerosols and upper versus lower tropospheric aerosols), sampling issue, and cloud contamination, are discussed. However, a clear causal explanation for the observed patterns remains elusive. Further investigation is needed to unravel this complex aerosol-rainfall relationship.

  13. A Novel Tool for Simulating Aerosol-cloud Interactions with a Sectional Model Implemented to a Large-Eddy Simulator

    NASA Astrophysics Data System (ADS)

    Tonttila, J.; Romakkaniemi, S.; Kokkola, H.; Maalick, Z.; Korhonen, H.; Liqing, H.

    2015-12-01

    A new cloud-resolving model setup for studying aerosol-cloud interactions, with a special emphasis on partitioning and wet deposition of semi-volatile aerosol species, is presented. The model is based on modified versions of two well-established model components: the Large-Eddy Simulator (LES) UCLALES, and the sectional aerosol model SALSA, previously employed in the ECHAM climate model family. Implementation of the UCLALES-SALSA is described in detail. As the basis for this work, SALSA has been extended to include a sectional representation of the size distributions of cloud droplets and precipitation. Microphysical processes operating on clouds and precipitation have also been added. Given our main motivation, the cloud droplet size bins are defined according to the dry particle diameter. The droplet wet diameter is solved dynamically through condensation equations, but represents an average droplet diameter inside each size bin. This approach allows for accurate tracking of the aerosol properties inside clouds, but minimizes the computational cost. Since the actual cloud droplet diameter is not fully resolved inside the size bins, processes such as precipitation formation rely on parameterizations. For realistic growth of drizzle drops to rain, which is critical for the aerosol wet deposition, the precipitation size bins are defined according to the actual drop size. With these additions, the implementation of the SALSA model replaces most of the microphysical and thermodynamical components within the LES. The cloud properties and aerosol-cloud interactions simulated by the model are analysed and evaluated against detailed cloud microphysical boxmodel results and in-situ aerosol-cloud interaction observations from the Puijo measurement station in Kuopio, Finland. The ability of the model to reproduce the impacts of wet deposition on the aerosol population is demonstrated.

  14. Ammonia emissions in the United States, European Union, and China derived by high-resolution inversion of ammonium wet deposition data: Interpretation with a new agricultural emissions inventory (MASAGE_NH3)

    EPA Science Inventory

    We use the adjoint of a global 3-D chemical transport model (GEOS-Chem) to optimizeammonia (NH3+4 wet deposition fluxes. Optimized emissions are derive...

  15. Inertial deposition of nanoparticle chain aggregates: Theory and comparison with impactor data for ultrafine atmospheric aerosols

    NASA Astrophysics Data System (ADS)

    Barone, Teresa L.; Lall, Anshuman Amit; Zhu, Yifang; Yu, Rong-Chung; Friedlander, Sheldon K.

    2006-10-01

    mixture of diesel and internal combustion engine emissions. Aggregates collected at LAX were most likely present as a result of aircraft emissions. In both measurements, the aggregate aerodynamic diameters calculated from the primary particle diameter were fairly close to the stage cutoff diameter. The number of primary particles per aggregate varied one order of magnitude for particles depositing on the same stage. The average aggregate surface area per unit volume was 2.41 × 106 cm-1 and 2.59 × 106 cm-1 (50 nm d a,50) and 1.81 × 106 cm-1 and 1.68 × 106 cm-1 (75 nm d a,50) for near-freeway and LAX measurements, respectively. These preliminary measurements are consistent with values calculated from theory.

  16. Three air quality studies: Great Lakes ozone formation and nitrogen dry deposition; and Tucson aerosol chemical characterization

    NASA Astrophysics Data System (ADS)

    Foley, Theresa

    (arsenic, beryllium, cadmium, chromium, cobalt, lead, manganese, and nickel) in the southern Tucson metropolitan area. A Tucson company that uses beryllium oxide to manufacture thermally conductive ceramics has prompted strong citizen concern. This study found that the study area has good air quality with respect to PM10 and metals, with ambient concentrations meeting US Environmental Protection Agency and World Health Organization standards. Beryllium was detected only once (during a dust storm) and was ascribed to naturally-occurring beryllium in the suspended soil. The third paper (to be submitted to the Journal of Great Lakes Research) studies nitrogen dry deposition over Lake Michigan and Lake Superior. Numerous studies have shown that wet and dry deposition of nitrogen has contributed to the eutrophication of coastal waters and declining productivity of marine fisheries. Nitrogen dry deposition over the Great Lakes themselves, as opposed to the shorelines, has not been documented in the peer-reviewed literature. This paper calculates nitrogen dry deposition over Lake Michigan and Lake Superior, using aircraft measurements from the LADCO Aircraft Study, and finds that over-water, nitrogen dry deposition is a significant source of nitrogen to Lake Michigan and Lake Superior.

  17. Chemical vapor deposition of YBa{sub 2}Cu{sub 3}O{sub x} in a cold plasma reactor using an aerosol vaporization technique

    SciTech Connect

    Chung, Y.S.; Hill, D.N.; Carter, W.B.; Lackey, W.J.

    1996-03-01

    A plasma-enhanced chemical vapor deposition technique, utilizing an aerosol decomposition/vaporization process in a cold plasma reactor, was used to form YBa{sub 2}Cu{sub 3}O{sub x} (YBCO) thin films on single-crystal MgO substrates. Aerosol droplets of the precursors were generated by an ultrasonic nebulizer operating at 1.63 MHz, while a 50 kW rf generator, operating at 2.87 MHz, was used to create the plasma and heat a stainless steel susceptor. Nitrate, acetylacetonate, and tetramethylheptanedionate compounds were used as precursors, and distilled water, ethyl alcohol, and an aqueous benzoic acid solution were investigated as solvents for the aerosol solution. The effects of the solubility and decomposition temperature of the chemical precursors, and the vapor pressure of the solvents, on the microstructure and phase assemblage of the deposits were determined. Specific combinations of substrate temperature, in the range of 800--940 C, and oxygen partial pressure, in the range of 0.3--2.7 kPa, were found to produce in situ, crystalline, stoichiometric YBCO films.

  18. On the influence of DC electric fields on the aerosol assisted chemical vapor deposition growth of photoactive titanium dioxide thin films.

    PubMed

    Romero, Luz; Binions, Russell

    2013-11-05

    Titanium dioxide thin films were deposited on fluorine doped tin oxide glass substrate from the electric field assisted aerosol chemical vapor deposition (EACVD) reaction of titanium isopropoxide (TTIP, Ti(OC3H7)4) in toluene on glass substrates at a temperature of 450 °C. DC electric fields were generated by applying a potential difference between the electrodes of the transparent coated oxide coated glass substrates during the deposition. The deposited films were characterized using scanning electron microscopy, X-ray diffraction, atomic force microscopy, Raman spectroscopy, and UV-vis spectroscopy. The photoactivity and hydrophilicity of the deposited films were also analyzed using a dye-ink test and water-contact angle measurements. The characterization work revealed that the incorporation of DC electric fields produced significant reproducible changes in the film microstructure, preferred crystallographic orientation, roughness, and film thickness. Photocatalytic activity was calculated from the half-time (t1/2) or time taken to degrade 50% of the initial resazurin dye concentration. A large improvement in photocatalytic activity was observed for films deposited using an electric field with a strong orientation in the (004) direction (t1/2 17 min) as compared to a film deposited with no electric field (t1/2 40 min).

  19. American Association for Aerosol Research (AAAR) `95

    SciTech Connect

    1995-12-31

    The Fourteenth annual meeting of the American Association for Aerosol Research was held October 9-13, 1995 at Westin William Penn Hotel in Pittsburgh, PA. This volume contains the abstracts of the papers and poster sessions presented at this meeting, grouped by the session in which they were presented as follows: Radiation Effects; Aerosol Deposition; Collision Simulations and Microphysical Behavior; Filtration Theory and Measurements; Materials Synthesis; Radioactive and Nuclear Aerosols; Aerosol Formation, Thermodynamic Properties, and Behavior; Particle Contamination Issues in the Computer Industry; Pharmaceutical Aerosol Technology; Modeling Global/Regional Aerosols; Visibility; Respiratory Deposition; Biomass and Biogenic Aerosols; Aerosol Dynamics; Atmospheric Aerosols.

  20. Bacterial communities in urban aerosols collected with wetted-wall cyclonic samplers and seasonal fluctuations of live and culturable airborne bacteria.

    PubMed

    Ravva, Subbarao V; Hernlem, Bradley J; Sarreal, Chester Z; Mandrell, Robert E

    2012-02-01

    Airborne transmission of bacterial pathogens from point sources (e.g., ranches, dairy waste treatment facilities) to areas of food production (farms) has been suspected. Determining the incidence, transport and viability of extremely low levels of pathogens require collection of high volumes of air and characterization of live bacteria from aerosols. We monitored the numbers of culturable bacteria in urban aerosols on 21 separate days during a 9 month period using high volume cyclonic samplers at an elevation of 6 m above ground level. Culturable bacteria in aerosols fluctuated from 3 CFU to 6 million CFU/L of air per hour and correlated significantly with changes in seasonal temperatures, but not with humidity or wind speed. Concentrations of viable bacteria determined by fluorescence staining and flow cytometry correlated significantly with culturable bacteria. Members of the phylum Proteobacteria constituted 98% of the bacterial community, which was characterized using 16S rRNA gene sequencing using DNA from aerosols. Aquabacterium sp., previously characterized from aquatic environments, represented 63% of all clones and the second most common were Burkholderia sp; these are ubiquitous in nature and some are potential human pathogens. Whole genome amplification prior to sequencing resulted in a