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Sample records for atmospheric deposition resuspension

  1. Atmospheric deposition and resuspension of suspended particulates in urban area

    NASA Astrophysics Data System (ADS)

    Lim, Jeong-Hee

    2006-12-01

    Emissions of trace metals to the atmosphere and sub-sequential deposition and resuspension process represent a potential threat to water bodies, ecosystems, and public health throughout coastal Los Angeles. However, few studies have quantified atmospheric deposition in Southern California. This research aims to increase our understanding of the role of atmospheric deposition as a potentially important source of trace metals and the role of subsequent resuspension on aquatic environments in the Los Angeles coastal region. Seasonal measurements of dry deposition were made at six urban and one non-urban site for one year. Dry deposition was significantly higher at urban sites compared with the non-urban site, and the dry atmospheric deposition is dominated by particles larger than 10 mum. The measured concentration and deposition flux at six sites within urban area is spatially uniform, indicating a major role for resuspension in the fate of particles by dispersing particle---associated metals regionally. In addition, atmospheric deposition and runoff measurements (wet and dry) of particle-associated trace metals within an urban catchment made over a year indicates the dominance of dry deposition in Southern California, and shows that atmospheric deposition can potentially account for as much as 57 to 100% of the total trace metal loads in stormwater from the catchment. Furthermore, freeways and other major roads act as a source of locally high deposition rates of copper, lead and zinc, primarily because of increased emissions of particles larger than 6 mum from the freeway. Because of resuspension, these large particles are consistently observed at urban background sites, but as a smaller percentage of the total mass as distance from the emission source increases. A modified Gaussian plume model shows that dispersion may he the most significant process of controlling the spatial variation of concentration and deposition near freeway. Finally, this study demonstrates

  2. In Vitro Exposures in Diesel Exhaust Atmospheres: Resuspension of PM from Filters Verses Direct Deposition of PM from Air

    PubMed Central

    Lichtveld, Kim M.; Ebersviller, Seth M.; Sexton, Kenneth G.; Vizuete, William; Jaspers, Ilona; Jeffries, Harvey E.

    2012-01-01

    One of the most widely used in vitro particulate matter (PM) exposures methods is the collection of PM on filters, followed by resuspension in a liquid medium, with subsequent addition onto a cell culture. To avoid disruption of equilibria between gases and PM, we have developed a direct in vitro sampling and exposure method (DSEM) capable of PM-only exposures. We hypothesize that the separation of phases and post-treatment of filter-collected PM significantly modifies the toxicity of the PM compared to direct deposition, resulting in a distorted view of the potential PM health effects. Controlled test environments were created in a chamber that combined diesel exhaust with an urban-like mixture. The complex mixture was analyzed using both the DSEM and concurrently-collected filter samples. The DSEM showed that PM from test atmospheres produced significant inflammatory response, while the resuspension exposures at the same exposure concentration did not. Increasing the concentration of resuspended PM sixteen times was required to yield measurable IL-8 expression. Chemical analysis of the resuspended PM indicated a total absence of carbonyl compounds compared to the test atmosphere during the direct-exposures. Therefore, collection and resuspension of PM into liquid modifies its toxicity and likely leads to underestimating toxicity. PMID:22834915

  3. Atmospheric deposition, resuspension and root uptake of plutonium in corn and other grain-producing agroecosystems near a nuclear fuel facility

    SciTech Connect

    Pinder, J.E. III; McLeod, K.W.; Adriano, D.C.; Corey, J.C.; Boni, A.L.

    1989-12-31

    Plutonium released to the environment may contribute to dose to humans through inhalation or ingestion of contaminated foodstuffs. Plutonium contamination of agricultural plants may result from interception and retention of atmospheric deposition, resuspension of Pu-bearing soil particles to plant surfaces, and root uptake and translocation to grain. Plutonium on vegetation surfaces may be transferred to grain surfaces during mechanical harvesting. Data obtained from corn grown near the US Department of Energy`s H-Area nuclear fuel chemical separations facility on the Savannah River Site was used to estimated parameters of a simple model of Pu transport in agroecosystems. The parameter estimates for corn were compared to those previously obtained for wheat and soybeans. Despite some differences in parameter estimates among crops, the relative importances of atmospheric deposition, resuspension and root uptake were similar among crops. For even small deposition rates, the relative importances of processes for Pu contamination of corn grain should be: transfer of atmospheric deposition from vegetation surfaces to grain surfaces during combining > resuspension of soil to grain surfaces > root uptake. Approximately 3.9 {times} 10{sup {minus}5} of a year`s atmospheric deposition is transferred to grain. Approximately 6.2 {times} 10{sup {minus}9} of the Pu inventory in the soil is resuspended to corn grain, and a further 7.3 {times} 10{sup {minus}10} of the soil inventory is absorbed by roots and translocated to grains.

  4. Atmospheric deposition, resuspension and root uptake of plutonium in corn and other grain-producing agroecosystems near a nuclear fuel facility

    SciTech Connect

    Pinder, J.E. III; McLeod, K.W.; Adriano, D.C. ); Corey, J.C.; Boni, A.L. )

    1989-01-01

    Plutonium released to the environment may contribute to dose to humans through inhalation or ingestion of contaminated foodstuffs. Plutonium contamination of agricultural plants may result from interception and retention of atmospheric deposition, resuspension of Pu-bearing soil particles to plant surfaces, and root uptake and translocation to grain. Plutonium on vegetation surfaces may be transferred to grain surfaces during mechanical harvesting. Data obtained from corn grown near the US Department of Energy's H-Area nuclear fuel chemical separations facility on the Savannah River Site was used to estimated parameters of a simple model of Pu transport in agroecosystems. The parameter estimates for corn were compared to those previously obtained for wheat and soybeans. Despite some differences in parameter estimates among crops, the relative importances of atmospheric deposition, resuspension and root uptake were similar among crops. For even small deposition rates, the relative importances of processes for Pu contamination of corn grain should be: transfer of atmospheric deposition from vegetation surfaces to grain surfaces during combining > resuspension of soil to grain surfaces > root uptake. Approximately 3.9 {times} 10{sup {minus}5} of a year's atmospheric deposition is transferred to grain. Approximately 6.2 {times} 10{sup {minus}9} of the Pu inventory in the soil is resuspended to corn grain, and a further 7.3 {times} 10{sup {minus}10} of the soil inventory is absorbed by roots and translocated to grains.

  5. Emission, transport, deposition, and re-suspension of radionuclides from Fukushima Dai-ichi Nuclear Power Plant in the atmosphere - Overview of 2-year investigations in Japan

    NASA Astrophysics Data System (ADS)

    Kita, Kazuyuki; Igarashi, Yasuhiro; Yoshida, Naohiro; Nakajima, Teruyuki

    2013-04-01

    Following a huge earthquake and tsunami in Eastern Japan on 11 March, 2011, the accident in Fukushima Dai-ichi Nuclear Power Plant (FDNPP) occurred to emit a large amount of artificial radionuclides to the environment. Soon after the FDNPP accident, many Japanese researchers, as well as researchers in other countries, started monitoring radionuclides in various environmental fields and/or model calculations to understand extent and magnitude of radioactive pollution. In this presentation, we overview these activities for the atmospheric radionuclides in Japan as followings: 1. Investigations to evaluate radionuclide emissions by explosions at FNDPP in March 2011 and to estimate the respiration dose of the radiation at this stage. 2. Investigations to evaluate atmospheric transport and deposition processes of atmospheric radionuclide to determine the extent of radionuclide pollution. -- Based on results of the regular and urgent monitoring results, as well as the mapping of the distribution of radionuclide s accumulated by the deposition to the ground, restoration of their time-dependent emission rates has been tried, and processes determining atmospheric concentration and deposition to the ground have been investigated by using the model calculations. 3. Monitoring of the atmospheric concentrations of radionuclide after the initial, surge phase of FNDPP accident. 4. Investigations to evaluate re-suspension of radionuclide from the ground, including the soil and the vegetation. -- Intensive monitoring of the atmospheric concentrations and deposition amount of radionuclide after the initial, surge phase of the accident enable us to evaluate emission history from FNDPP, atmospheric transport and deposition processes, chemical and physical characteristics of atmospheric radionuclide especially of radio cesium, and re-suspension processes which has become dominant process to supply radio cesium to the atmosphere recently.

  6. Atmospheric Radionuclides from the FDNPP Accident-Four years' observations in Tsukuba, Japan and immediate resuspension

    NASA Astrophysics Data System (ADS)

    Igarashi, Yasuhito; Kajino, Mizuo; Zaizen, Yuji; Adachi, Kouji; Mikami, Masao

    2015-04-01

    The accident of Fukushima Dai-Ichi Nuclear Power Plant (FDNPP) of the Tokyo Electric Power Corporation arisen by the hit of great earthquake and tsunami in March 11, 2011, emitted abundant fresh radioactive material to the atmospheric environment. With 4-years' observation for the Fukushima radioactivity at the Meteorological Research Institute, Japan (MRI) the persisting resuspension has been observed. The resuspension seems still in difficulty to give forecast by computer modeling; the observations are indispensable bodies of the research even in the future. As a primary approach, immediate re-suspension factors were roughly estimated with modeled deposition amounts by the first plume to the Kanto district and the observed minimum activity concentration between two plume events, i.e. Mar 17 09JST to Mar. 20 09JST, by assuming mass closure between re-suspension from the contaminated surface and outflow by horizontal advection and turbulence vertical mixing as follows: Diki ΔCi- Δ2Ci- Δz = U Δx + Kz Δz2 , where i indicates radionuclides namely 137Cs and 131I, Diindicates modeled total (gas+aerosol) cumulative deposition (Bq/m2) by Mar 17 09JST, ki is the re-suspension factor (/s), U and Kz are modeled space- and time- averaged horizontal wind speed (m/s) and vertical turbulent diffusivity (m2/s), respectively, Ci indicates time-averaged observed concentration of radionuclides (9.75×10-4 and 3.14×10-1 Bq/m3 for 137Cs and 131I, respectively), and Δx and Δz are horizontal and vertical length of space where the above mass closure is obtained. In order to obtain the horizontal and vertical gradient terms on the right hand of the equation, concentrations outside the space are assumed zero (no inflow to the space). The re-suspension factors for 137Cs and 131I are 7.0×10-6 and 5.3×10-4 (/s), respectively, for the smallest volume of space (Δx and Δz are 3 km and 100 m, respectively). Those for 137Cs and 131I varied 1.6×10-6-1.5×10-5 (6.1×10-6 on average) and

  7. Benthic biofilm structure controls the deposition-resuspension dynamics of fine clay particles

    NASA Astrophysics Data System (ADS)

    Hunter, W. R.; Roche, K. R.; Drummond, J. D.; Boano, F.; Packman, A. I.; Battin, T. J.

    2015-12-01

    In fluvial ecosystems the alternation of deposition and resuspension of particles represents an important pathway for the downstream translocation of microbes and organic matter. Such particles can originate from algae and microbes, the spontaneous auto-aggregation of organic macromolecules (e.g., "river sown"), terrestrial detritus (traditionally classified as "particulate organic matter"), and erosive mineral and organo-mineral particles. The transport and retention of particles in headwater streams is associated with biofilms, which are surface-attached microbial communities. Whilst biofilm-particle interactions have been studied in bulk, a mechanistic understanding of these processes is lacking. Parallel macroscale/microscale observations are required to unravel the complex feedbacks between biofilm structure, coverage and the dynamics of deposition and resuspension. We used recirculating flume mesocosms to test how changes in biofilm structure affected the deposition and resuspension of clay-sized (< 10 μm) particles. Biofilms were grown in replicate 3-m-long recirculating flumes over variable lengths of time (0, 14, 21, 28, and 35) days. Fixed doses of fluorescent clay-sized particles were introduced to each flume and their deposition was traced over 30 minutes. A flood event was then simulated via a step increase in flowrate to quantify particle resuspension. 3D Optical Coherence Tomography was used to determine roughness, areal coverage and height of biofilms in each flume. From these measurements we characterised particle deposition and resuspension rates, using continuous time random walk modelling techniques, which we then tested as responses to changes in biofilm coverage and structure under both base-flow and flood-flow scenarios. Our results suggest that biofilm structural complexity is a primary control upon the retention and downstream transport of fine particles in stream mesocosms.

  8. Resuspension of deposited radioactive material from the Fukushima Daiichi NPP site

    NASA Astrophysics Data System (ADS)

    Steinhauser, Georg; Niisoe, Tamon; Harada, Kouji H.; Shozugawa, Katsumi; Schneider, Stephanie; Synal, Hans-Arno; Walther, Clemens; Christl, Marcus; Nanba, Kenji; Ishikawa, Hirohiko; Koizumi, Akio

    2016-04-01

    Releases of radionuclides from the Fukushima nuclear accident are typically associated with the atmospheric discharges in the early phase of the accident in spring 2011. Analysis of weekly air filters, however, has revealed sporadic releases of radionuclides long after the Fukushima Daiichi reactors were stabilized. One major discharge was observed in August 2013 in monitoring stations in the Minamisoma area north of the Fukushima Daiichi nuclear power plant (FDNPP). During this event, an air monitoring station in this previously scarcely contaminated area suddenly reported 137Cs activity levels that were 30-fold above the background. Together with atmospheric dispersion and deposition simulation, radionuclide analysis in soil indicated that debris removal operations conducted on the FDNPP site on August 19, 2013 are likely to be responsible for this late release of radionuclides. One soil sample in the center of the simulated plume exhibited a high 90Sr contamination (78 ± 8 Bq kg‑1) as well as a high 90Sr/137Cs ratio (0.04); both phenomena have usually been observed only in very close vicinity around the FDNPP. We estimate that through the resuspension of highly contaminated particles in the course of these earthmoving operations, gross 137Cs activity of ca. 2.8 × 1011 Bq has been released.

  9. Effect of recurrent sediment resuspension-deposition events on bioavailability of polycyclic aromatic hydrocarbons in aquatic environments

    NASA Astrophysics Data System (ADS)

    Dong, Jianwei; Xia, Xinghui; Wang, Minghu; Xie, Hui; Wen, Jiaojiao; Bao, Yimeng

    2016-09-01

    To investigate the effect of recurrent sediment resuspension-deposition events (RSRDEs) on bioavailability of polycyclic aromatic hydrocarbons (PAHs) in aquatic environments, a modified device was used to simulate three resuspension-deposition events with the sediment collected from the Yellow River. The results showed that the dissolved organic carbon (DOC)-water distribution coefficients of PAHs decreased with time during the first resuspension-deposition period. It indicates that some PAHs associated with organic carbon (OC) in suspended sediment (SPS) desorbed with the release of OC and became DOC-associated PAHs in the overlying water, then the PAHs desorbed from the DOC and became freely dissolved. After first 2-h suspension, only 1.90% of phenanthrene, 2.98% of pyrene, and 0.33% of chrysene in the overlying water came from pore-water; at least 61.6%, 89.6%, and 95.3% came from DOC-associated PAHs in SPS and the rests were released from the insoluble OC in SPS. The maximum desorption ratios in the original sediment were 20%, 12%, and 14% for phenanthrene, pyrene, and chrysene, respectively during the first resuspension-deposition event. The SPS concentration followed the sequence of the third > second > first resuspension event. This was because RSRDEs changed the SPS particle size and enhanced floc formation. There was no significant difference in the total dissolved PAH concentrations among the three resuspension events, while their freely dissolved concentrations followed the sequence of the third > second > first resuspension event. During deposition periods, more than half of the total/freely dissolved PAHs released during suspension still existed in the overlying water after 70-h deposition. This study suggests that the RSRDEs will increase the bioavailability of PAHs in aquatic environments, especially near the sediment-water interface, and the potential effects of PAHs during RSRDEs on fish/human in rivers and lakes should be considered in future

  10. Stochastic modeling of fine particle deposition, resuspension, and hyporheic exchange in rivers

    NASA Astrophysics Data System (ADS)

    Packman, Aaron; Drummond, Jennifer; Aubeneau, Antoine

    2013-04-01

    Fine suspended particles are responsible for substantial flux of organic matter and contaminants in rivers. Further, microorganisms delivered from the terrestrial system or resuspended from benthic and hyporheic biofilms also propagate downstream in rivers, providing connectivity in the river microbial community. Because fine particle concentrations are often similar along the length of rivers, there has been a tendency to think that their dynamics are simple. Historically, fine suspended particles have been considered to show little interaction with streambed sediments. This is a fallacy. Recent observations have demonstrated that fine particles show complex dynamics in rivers, including ongoing deposition and resuspension. This provides substantial opportunity for interaction with benthic and hyporheic sediments and biofilms, which can lead to enhanced processing of fine particulate organic carbon, accumulation of pathogens in riverbeds, and mixing of particle-bound contaminants into bed sediments. Here I will briefly review current understanding of fine particle deposition, resuspension, and hyporheic exchange processes, develop a conceptual model for fine particle dynamics in rivers, and present a stochastic modeling framework that can represent most of these processes. I will close by discussing the limits of current modeling capability and prospects for future development of more general models.

  11. Advanced receptor modelling for the apportionment of road dust resuspension to atmospheric PM

    NASA Astrophysics Data System (ADS)

    Amato, F.; Pandolfi, M.; Escrig, A.; Querol, X.; Alastuey, A.; Pey, J.; Perez, N.; Hopke, P. K.

    2009-04-01

    Fugitive emissions from traffic resuspension can often represent an important source of atmospheric particulate matter in urban environments, especially when the scarce precipitations favour the accumulation of road dust. Resuspension of road dust can lead to high exposures to heavy metals, metalloids and mineral matter. Knowing the amount of its contribution to atmospheric PM is a key task for establishing eventual mitigation or preventive measures. Factor analysis techniques are widely used tools for atmospheric aerosol source apportionment, based on the mass conservation principle. Paatero and Tapper (1993) suggested the use of a Weighted Least Squares scheme with the aim of obtaining a minimum variance solution. Additionally they proposed to incorporate the basic physical constraint of non negativity, calling their approach Positive Matrix Factorization (PMF), which can be performed by the program PMF2 released by Paatero (1997). Nevertheless, Positive Matrix Factorization can be either solved with the Multilinear Engine (ME-2), a more flexible program, also developed by Paatero (1999), which can solve any model consisting in sum of products of unknowns. The main difference with PMF2 is that ME-2 does not solve only well-defined tasks, but its actions are defined in a "script file" written in a special-purpose programming language, allowing incorporating additional tasks such as data processing etc. Thus in ME-2 a priori information, e.g. chemical fingerprints can be included as auxiliary terms of the object function to be minimized. This feature of ME-2 make it especially suitable for source apportionment studies where some knowledge (chemical ratios, profiles, mass conservation etc) of involved sources is available. The aim of this study was to quantify the contribution of road dust resuspension in PM10, PM2.5 and PM1 data set from Barcelona (Spain). Given that recently the emission profile of local road dust was characterized (Amato et al., in press

  12. Tracing the Depositional Fluxes of Po-210 and Pb-210 As a Tool for Sediment Resuspension Study in a Shallow Water System in Southeast Michigan

    NASA Astrophysics Data System (ADS)

    Baskaran, M. M.; Mudbidre, R.

    2014-12-01

    From the measurements of 210Po and 210Pb in atmospheric dry and bulk depositional flux and in aerosols in southeast Michigan, we observed the following: i) the 210Po/210Pb activity ratio in bulk precipitation was lower than that in aerosols and this was attributed to the possible presence of volatile 210Po in the atmosphere; and ii) it was proposed that only a small fraction of aerosols actively participate in the scavenging of particle-reactive radionuclides based on lack of correlation between the activity of 210Pb and aerosol mass concentration. We extended this study to investigate the particle-cycling in a shallow, dynamic freshwater system in southeast Michigan. The 210Po/210Pb activity ratios in bulk deposition is mostly <0.1 while in benthic sediments, this ratio is usually ~1.0. This activity ratio in finer resuspended sedimentary particulate matter is altered from the scavenging of Po and Pb derived from the atmospheric deposition, and thus, the 210Po/210Pb activity ratio in suspended particulate matter can be utilized as a tracer for particle cycling. We measured the concentrations 210Po and 210Pb in a suite of surficial benthic sediments and particulate matter collected in sediment traps from five different locations in the Clinton River that discharges in to Lake St. Clair in southeast Michigan to quantify the sediment resuspension rates and to determine the particle residence time. The mean 210Po/210Pb activity ratio of suspended trap and surficial bottom sediments were 0.72 and 0.75, respectively, indicating that the sediment trap particles were mostly derived from resuspended bottom sediments. Particle residence time varied from 0.3 to 4 days for 210Pb and 0.9 to 13.4 days for 210Po. Sediment resuspension rate calculated via a single box model approach yielded a mean resuspension rate of 0.5 g cm-2 yr-1 using 210Pb and 0.2 g cm-2 yr-1 using 210Po. A comparison of the 210Po and 210Pb fluxes in the sediment trap to that in the direct atmospheric

  13. Particle resuspension via human activity

    NASA Astrophysics Data System (ADS)

    Qian, Jing

    This dissertation consists of three correlated parts that are related to particle resuspension from floorings in indoor environment. The term resuspension in this dissertation refers the re-entrainment of deposited particles into atmosphere via mechanic disturbances by human activity indoors, except where it is specified. The first part reviews the literature related to particle resuspension. Fundamental concepts and kinetics of resuspension of particles were extracted from previous studies. Suggestions for future research on indoor particle resuspension have been given based on the literature reviews and the findings of part 2 and part 3. The second part involved 54 resuspension experiments conducted in a room-scale environmental chamber. Three floorings types and two ventilation configurations were tested. Air exchange rate were fixed during the experiments, and the temperature/RH were monitored. The airborne particle concentration was measured by an array of optical particle counters (OPCs) in the chamber. Resuspension rates were estimated in size ranges of 0.8--1, 1.0--2.0, 2.0--5.0, and 5.0--10 mum ranging from 10-5--10 -2 hr-1, with higher resuspension rates associated with larger particles. Resuspension via walking activity varied from experiment to experiment. A "heavy and fast" walking style was associated with a higher resuspension rate than a less active style. Given the same floor loading of the test particles, resuspension rates for the carpeted floor were on the same order of magnitude but significantly higher than those for the hard floor. In the third part, an image analysis method (IAM) was adapted to characterize the particle distribution on fabric floorings. The IAM results showed the variability of particles loading on various carpets. The dust particles on fibers from ten carpets vary in sizes. The normal dust loading varies from house to house from 3.6x106 particles/cm2 to 8.2x106 particles/cm2. The dust particle number distribution for size

  14. Numerical modeling of mixed sediment resuspension, transport, and deposition during the March 1998 episodic events in southern Lake Michigan

    SciTech Connect

    Lee, Cheegwan; Schwab, David J.; Beletsky, Dmitry; Stroud, Jonathan; Lesht, B. M.

    2007-02-17

    A two-dimensional sediment transport model capable of simulating sediment resuspension of mixed (cohesive+noncohesive) sediment is developed and applied to quantitatively simulate the March 1998 resuspension events in southern Lake Michigan. Some characteristics of the model are the capability to incorporate several floc size classes, a physically-based settling velocity formula, bed armoring, and sediment availability limitation. Important resuspension parameters were estimated from field and laboratory measurement data. The model reproduced the resuspension plume (observed by the SeaWIFS satellite and field instruments) and recently measured sedimentation rate distribution (using radiotracer techniques) fairly well. Model results were verified with field measurements of suspended sediment concentration and settling flux (by ADCPs and sediment traps). Both wave conditions and sediment bed properties (critical shear stress, fine sediment fraction, and limited sediment availability or source) are the critical factors that determine the concentration distribution and width of the resuspension plume. The modeled sedimentation pattern shows preferential accumulation of sediment on the eastern side of the lake, which agrees with the observed sedimentation pattern despite a predominance of particle sources from the western shoreline. The main physical mechanisms determining the sedimentation pattern are 1) the two counter-rotating circulation gyres producing offshore mass transport along the southeastern coast during northerly wind and 2) the settling velocity of sediment flocs which controls the deposition location.

  15. Numerical modeling of mixed sediment resuspension, transport, and deposition during the March 1998 episodic events in southern Lake Michigan.

    SciTech Connect

    Lee, C.; Schwab, D. J.; Beletsky, D.; Stroud, J.; Lesht, B.; PNNL; NOAA; Univ. of Michigan; Univ. of Pennsylvania

    2007-02-17

    A two-dimensional sediment transport model capable of simulating sediment resuspension of mixed (cohesive plus noncohesive) sediment is developed and applied to quantitatively simulate the March 1998 resuspension events in southern Lake Michigan. Some characteristics of the model are the capability to incorporate several floc size classes, a physically based settling velocity formula, bed armoring, and sediment availability limitation. Important resuspension parameters were estimated from field and laboratory measurement data. The model reproduced the resuspension plume (observed by the SeaWIFS satellite and field instruments) and recently measured sedimentation rate distribution (using radiotracer techniques) fairly well. Model results were verified with field measurements of suspended sediment concentration and settling flux (by ADCPs and sediment traps). Both wave conditions and sediment bed properties (critical shear stress, fine sediment fraction, and limited sediment availability or source) are the critical factors that determine the concentration distribution and width of the resuspension plume. The modeled sedimentation pattern shows preferential accumulation of sediment on the eastern side of the lake, which agrees with the observed sedimentation pattern despite a predominance of particle sources from the western shoreline. The main physical mechanisms determining the sedimentation pattern are (1) the two counter-rotating circulation gyres producing offshore mass transport along the southeastern coast during northerly wind and (2) the settling velocity of sediment flocs which controls the deposition location.

  16. Model testing using Chernobyl data: III. Atmospheric resuspension of radionuclides in Ukrainian regions impacted by Chernobyl fallout

    SciTech Connect

    Garger, E.K.; Hoffman, F.O.; Miller, C.W.

    1996-01-01

    The {open_quotes}Resuspension{close_quotes} scenario is designed to test models for atmospheric resuspension of radionuclides from contaminated soils. Resuspension can be a secondary source of contamination after a release has stopped, as well as a source of contamination for people and areas not exposed to the original release. The test scenario describes three exposure situations: (1) locations within the highly contaminated 30-km zone at Chernobyl, where exposures to resuspended material are probably dominated by local processes; (2) an urban area (Kiev) outside the 30-km zone, where local processes include extensive vehicular traffic; and (3) a location 40 to 60 km west of the Chernobyl reactor, where upwind sources of contamination are important. Input data include characteristics of the {sup 137}Cs ground contamination around specific sites, climatological data for the sites, characteristics of the terrain and topography, and locations of the sampling sites. Predictions are requested for average air concentrations of {sup 137}Cs at specified locations due to resuspension of Chernobyl fallout and for specified resuspension factors and rates. Test data (field measurements) are available for all endpoints. 9 refs., 4 figs., 11 tabs.

  17. Beryllium-7 as a tracer of short-term sediment deposition and resuspension in the Fox River Wisconsin

    USGS Publications Warehouse

    Fitzgerald, S.A.; Klump, J.V.; Swarzenski, P.W.; Mackenzie, R.A.; Richards, K.D.

    2001-01-01

    Short-term (???monthly) sediment deposition and resuspension rates of surficial bed sediments in two PCB-laden impoundments on the Fox River, WI, were determined in the summer and fall of 1998 using 7Be, a naturally occurring radioisotope produced in the atmosphere. Decay-corrected activities and inventories of 7Be were measured in bed sediment and in suspended particles. Beryilium-7 activities generally decreased with depth in the top 5-10 cm of sediments and ranged from undetectable to ???0.9 pCi cm-3. Inventories of 7Be, calculated from the sum of activities from all depths, ranged from 0.87 to 3.74 pCi cm-2, and the values covaried between sites likely reflecting a common atmospheric input signal. Activities of 7Be did not correlate directly with rainfall. Partitioning the 7Be flux into "new" and "residual" components indicated that net deposition was occurring most of the time during the summer. Net erosion, however, was observed at the upstream site from the final collection in the fall. This erosion event was estimated to have removed 0.10 g (cm of sediment)-2, corresponding to ???0.5 cm of sediment depth, and ???6-10 kg of polychlorinated biphenyls (PCBs) over the whole deposit. Short-term accumulation rates were up to ???130 times higher than the long-term rates calculated from 137Cs profiles, suggesting an extremely dynamic sediment transport environment, even within an impounded river system.Short-term (approximately monthly) sediment deposition and resuspension rates of surficial bed sediments in two PCB-laden impoundments on the Fox River, WI, were determined in the summer and fall of 1998 using 7Be, a naturally occurring radioisotope produced in the atmosphere. Decay-corrected activities and inventories of 7Be were measured in bed sediment and in suspended particles. Beryllium-7 activities generally decreased with depth in the top 5-10 cm of sediments and ranged from undetectable to approximately 0.9 pCi cm-3. Inventories of 7Be, calculated from the

  18. A "TEST OF CONCEPT" COMPARISON OF AERODYNAMIC AND MECHANICAL RESUSPENSION MECHANISMS FOR PARTICLES DEPOSITED ON FIELD RYE GRASS (SECALE CERCELE). PART I. RELATIVE PARTICLE FLUX RATES

    EPA Science Inventory

    Resuspension of uniform latex micro spheres deposited on a single seed pod of field rye grass stalk and head was investigated experimentally in a wind tunnel. The experiment was designed to distinguish aerodynamic (viscous and turbulent) mechanisms from mechanical resuspension re...

  19. Deposition of Atmospheric Pollutants

    NASA Astrophysics Data System (ADS)

    Malet, L. M.

    Deposition of Atmospheric Pollutants, containing the proceedings of a colloquium held at Oberursel/Taunus, FRG, November 9-11, 1981, is divided into three main parts: dry deposition; wet deposition; and deposition on plants and vegetation.The 20 articles in the volume permit a fair survey of present-day knowledge and will be a useful tool to all working on the topic. Pollution by deposition of either the dry or wet sort is very insidious; its importance only appears in the long range, when its effects are or are almost irreversible. That is why concern was so long in emerging from decision makers.

  20. Modeling atmospheric particle deposition

    NASA Astrophysics Data System (ADS)

    Jackson, Msafiri M.

    Experimentally determined dry deposition velocities for atmospheric particles in the size range of 5-80 μm in diameter have been shown to be greater than predictions made with the current state-of-the-art (Sehmel-Hodgson) model which is based on wind tunnel experiment, particularly at higher wind speed. In this research, a model to predict the atmospheric dry deposition velocities of particles has been developed that is similar to a model developed for particle deposition in vertical pipes. The model uses a sigmoid curve to correlate nondimensional inertial deposition velocity (Vdi+) with dimensionless particle relaxation time (/tau+) and flow Reynolds number (Re). Vdi+ obtained from data collected in the atmosphere with particle size classifier system and a flat greased plate, Re, and /tau+ for particles between 1 and 100 μm diameter were fit with a sigmoid curve using the least square procedure to obtain coefficients for the sigmoid curve. Deposition velocities data for particles between 0.06 and 4 μm diameter developed by Sehmel-Hodgson model were used to introduce a Schmidt number (Sc) term to take care of Brownian diffusion. The atmospheric plate deposition velocity model is a function of Vst (Stokes settling velocity), V* (friction velocity), /tau+, Re, and Sc. Model application to 62 atmospheric data set revealed that: generated flux predictions agreed well with atmospheric measurements, and its performance is better than Sehmel-Hodgson model. By comparing the sigmoid curve coefficients developed for vertical pipe data with the coefficients developed for atmospheric data it is concluded that, the two types of deposition are similar when the effects of Re and /tau+ are properly considered. Sensitivity analysis for the model has revealed three distinct regions based on particle size. Of the three physical parameters (/tau+, Re, Sc) in the model, not more than two controls the deposition in any of the identified regions. The plate deposition model which is

  1. A "TEST OF CONCEPT" COMPARISON OF AERODYNAMIC AND MECHANICAL RESUSPENSION MECHANISMS FOR PARTICLES DEPOSITED ON FIELD RYE GRASS (SECALS CERCELE). PART 2. THRESHOLD MECHANICAL ENERGIES FOR RESUSPENSION PARTICLE FLUXES

    EPA Science Inventory

    Kinetic energy from the oscillatory impacts of the grass stalk against a stationary object was measured with a kinetic energy measuring device. These energy inputs were measured as part of a resuspension experiment of uniform latex microspheres deposited on a single rye grass see...

  2. Re-suspension of lead contaminated urban soil as a dominant source of atmospheric lead in Birmingham, Chicago, Detroit and Pittsburgh, USA

    NASA Astrophysics Data System (ADS)

    Laidlaw, Mark A. S.; Zahran, Sammy; Mielke, Howard W.; Taylor, Mark P.; Filippelli, Gabriel M.

    2012-03-01

    Soils in older areas of cities are highly contaminated by lead, due largely to past use of lead additives in gasoline, the use of lead in exterior paints, and industrial lead sources. Soils are not passive repositories and periodic re-suspension of fine lead contaminated soil dust particulates (or aerosols) may create seasonal variations of lead exposure for urban dwellers. Atmospheric soil and lead aerosol data from the Interagency Monitoring of Protected Visual Environments (IMPROVE) database were obtained for Pittsburgh (Pennsylvania), Detroit (Michigan), Chicago (Illinois), and Birmingham (Alabama), USA. In this study the temporal variations of atmospheric soil and lead aerosols in these four US cities were examined to determine whether re-suspended lead contaminated urban soil was the dominant source of atmospheric lead. Soil and lead-in-air concentrations were examined to ascertain whether lead aerosols follow seasonal patterns with highest concentrations during the summer and/or autumn. In addition, atmospheric soil and lead aerosol concentrations on weekends and Federal Government holidays were compared to weekdays to evaluate the possibility that automotive turbulence results in re-suspension of lead contaminated urban soil. The results show that the natural logs of atmospheric soil and lead aerosols were associated in Pittsburgh from April 2004 to July 2005 (R2 = 0.31, p < 0.01), Detroit from November 2003 to July 2005 (R2 = 0.49, p <0.01), Chicago from November 2003 to August 2005 (R2 = 0.32, p < 0.01), and Birmingham from May 2004 to December 2006 (R2 = 0.47, p < 0.01). Atmospheric soil and lead aerosols followed seasonal patterns with highest concentrations during the summer and/or autumn. Atmospheric soil and lead aerosols are 3.15 and 3.12 times higher, respectively, during weekdays than weekends and Federal Government holidays, suggesting that automotive traffic turbulence plays a significant role in re-suspension of contaminated roadside soils and

  3. Glacial atmospheric phosphorus deposition

    NASA Astrophysics Data System (ADS)

    Kjær, Helle Astrid; Dallmayr, Remi; Gabrieli, Jacopo; Goto-Azuma, Kumiko; Hirabayashi, Motohiro; Svensson, Anders; Vallelonga, Paul

    2016-04-01

    Phosphorus in the atmosphere is poorly studied and thus not much is known about atmospheric phosphorus and phosphate transport and deposition changes over time, though it is well known that phosphorus can be a source of long-range nutrient transport, e.g. Saharan dust transported to the tropical forests of Brazil. In glacial times it has been speculated that transport of phosphorus from exposed shelves would increase the ocean productivity by wash out. However whether the exposed shelf would also increase the atmospheric load to more remote places has not been investigated. Polar ice cores offer a unique opportunity to study the atmospheric transport of aerosols on various timescales, from glacial-interglacial periods to recent anthropogenic influences. We have for the first time determined the atmospheric transport of phosphorus to the Arctic by means of ice core analysis. Both total and dissolved reactive phosphorus were measured to investigate current and past atmospheric transport of phosphorus to the Arctic. Results show that glacial cold stadials had increased atmospheric total phosphorus mass loads of 70 times higher than in the past century, while DRP was only increased by a factor of 14. In the recent period we find evidence of a phosphorus increase over the past 50 yrs in ice cores close to human occupation likely correlated to forest fires. References: Kjær, Helle Astrid, et al. "Continuous flow analysis method for determination of dissolved reactive phosphorus in ice cores." Environmental science & technology 47.21 (2013): 12325-12332. Kjær, Helle Astrid, et al. "Greenland ice cores constrain glacial atmospheric fluxes of phosphorus." Journal of Geophysical Research: Atmospheres120.20 (2015).

  4. Atmospheric Mercury Deposition Monitoring – National Atmospheric Deposition Program (NADP)

    EPA Science Inventory

    The National Atmospheric Deposition Program (NADP) developed and operates a collaborative network of atmospheric mercury monitoring sites based in North America – the Atmospheric Mercury Network (AMNet). The justification for the network was growing interest and demand from many ...

  5. Transuranic resuspension

    SciTech Connect

    Sehmel, G.A.

    1984-04-01

    Characteristics of aged resuspension sources are more uncertain than those of new resuspension sources, which can be investigated using inert-particle controlled-tracer sources. Even though airborne concentrations are low, one aged uniform-area source which can be used for resuspension studies is the accumulated radionuclide fallout in the soil from stratospheric and tropospheric fallout debris. Airborne radionuclide concentrations from this source were investigated at convenient locations on the Hanford site. The objective is to summarize plutonium and americium resuspension research conducted by the Pacific Northwest Laboratory from 1977 to 1983. Airborne plutonium was determined at five sites in the Hanford area, and both plutonium and americium were determined at two Hanford sites. Airborne plutonium and americium were examined as a function of aerodynamic particle diameter, sampling height, wind speed increments, and wind direction increments. The following results are discussed: airborne radionuclide concentrations, ..mu..Ci/cm/sup 3/ of sampled air; radionuclide activity densities, ..mu..Ci/g of airborne solids; airborne plutonium fluxes, ..mu..Ci/(m/sup 2/ day); /sup 241/Am//sup 239 +240/Pu) activity ratios, (..mu..Ci /sup 241/Am)/(..mu..Ci/sup 239 +240/Pu); and airborne solid concentrations, ..mu..g/m/sup 3/ of sampled air. In addition, a relationship based on field data for aged plutonium sources at Bikini Atoll, the Hanford site, and Rocky Flats was developed to estimate the maximum expected plutonium activity density on airborne solids compared to activity densities for bulk surface-soil samples. As a result, it is possible to more accurately predict resuspension factor ranges as a function of the resuspension source activity densities. 31 references, 18 figures, 5 tables.

  6. Modeling the resuspension of ash deposited during the eruption of Eyjafjallajökull in spring 2010

    NASA Astrophysics Data System (ADS)

    Leadbetter, S. J.; Hort, M. C.; von Löwis, S.; Weber, K.; Witham, C. S.

    2012-10-01

    Eyjafjallajökull, a volcano in southern Iceland, erupted explosively in April and May 2010 depositing ash over a region of more than 3000 km2 to the east and southeast of the volcano. This deposited ash has been frequently remobilized by the wind causing concern for the health of Icelanders living in the region. An investigation was carried out to determine whether it would be possible to produce forecasts of days when high airborne ash concentrations were likely to occur. Information about the spatially varying surface characteristics of the region of deposited ash is not available so in the modeling approach adopted here ash is released from the surface at a rate proportional to the cube of the excess friction velocity (local friction velocity minus a threshold) only when the friction velocity exceeds a threshold. Movement of the resuspended ash is then modeled in a Lagrangian dispersion model. Modeled ash concentrations are compared to observed concentrations from two periods; PM10 observations between 23 May and 2 July 2010 and airborne particle counts between 21 September 2010 and 16 February 2011. More than 66% of the resuspension episodes between May and July are captured by the model and the relative magnitudes of the modeled episodes in this period are in good agreement with the observations. 66% of episodes between October and February are also captured by the model although there is an increase in the false alarm rate which appears to be due to the influence of precipitation.

  7. Overview of resuspension model: application to low level waste management

    SciTech Connect

    Healy, J.W.

    1980-01-01

    Resuspension is one of the potential pathways to man for radioactive or chemical contaminants that are in the biosphere. In waste management, spills or other surface contamination can serve as a source for resuspension during the operational phase. After the low-level waste disposal area is closed, radioactive materials can be brought to the surface by animals or insects or, in the long term, the surface can be removed by erosion. Any of these methods expose the material to resuspension in the atmosphere. Intrusion into the waste mass can produce resuspension of potential hazard to the intruder. Removal of items from the waste mass by scavengers or archeologists can result in potential resuspension exposure to others handling or working with the object. The ways in which resuspension can occur are wind resuspension, mechanical resuspension and local resuspension. While methods of predicting exposure are not accurate, they include the use of the resuspension factor, the resuspension rate and mass loading of the air.

  8. ATMOSPHERIC MERCURY TRANSPORT AND DEPOSITION

    EPA Science Inventory

    The current state of our scientific understanding the mercury cycle tells us that most of the mercury getting into fish comes from atmospheric deposition, but methylation of that mercury in aquatic systems is required for the concentrations in fish to reach harmful levels. We st...

  9. A coupled model of the airborne and surface concentration of radionuclides considering the resuspension-deposition process

    NASA Astrophysics Data System (ADS)

    Ichige, Hiroyuki; Hatano, Yuko; Onda, Yuichi

    2014-05-01

    We propose a new model of estimating the long-term behavior of both the airborne and the surface concentrations of radionuclides in the vicinity of 30 km of Fukushima plant. Our model consists of the following simultaneous equations: δC- = viδC-+ ΛupS - ΛdownC - ΛdecC (1) δt δxi δS- = - Λ S + Λ C - Λ S, (2) δt up down env where C is the airborne concentration of a specific nuclide, S the surface concentration, the suffix i is 1 or 2 (2 dimensional), v the effective wind velocity which migrates the radionuclides in the air, Λup the rate constant of resuspension process, Λdown of deposition process, Λdec the decay constant, and Λenv is the rate constant of the surface concentration decrease due to environmental factors such as runoff, washoff, infiltrations, and the vegetation effects. These equations are based on our former study (Hatano and Hatano, 1997; Hatano et al., 1998) which successfully reproduce the long-term decrease of airborne concentration of the Chernobyl data such as Cs-137, Cs-134, Ce-144, and Ru-106 over nearly a decade. The first equation of the present study is essentially the same as our previous studies, besides that we added a new term for deposition. The second equation is newly added in the present study which describes the behavior of the surface concentration. In Fukushima case, we found that the radiation risk is much higher than the airborne concentration. That is why we add the second equation. Since the new model requires parameter values of Λs we need to estimate these values from actual data. In order to do so, we apply the method of inverse problem and thereby estimate the values. We also do the spectral analysis of the dose rate (mainly from Cs-137, -134) and study if it is possible to estimate the resuspended amount from the ground surface.

  10. Methodology and Significance of Studies of Atmospheric Deposition in Highway Runoff

    USGS Publications Warehouse

    Colman, John A.; Rice, Karen C.; Willoughby, Timothy C.

    2001-01-01

    Atmospheric deposition and the processes that are involved in causing and altering atmospheric deposition in relation to highway surfaces and runoff were evaluated nationwide. Wet deposition is more easily monitored than dry deposition, and data on wet deposition are available for major elements and water properties (constituents affecting acid deposition) from the inter-agency National Atmospheric Deposition Program/ National Trends Network (NADP/NTN). Many trace constituents (metals and organic compounds) of interest in highway runoff loads, however, are not included in the NADP/NTN. Dry deposition, which constitutes a large part of total atmospheric deposition for many constituents in highway runoff loads, is difficult to monitor accurately. Dry-deposition rates are not widely available. Many of the highway-runoff investigations that have addressed atmospheric-deposition sources have had flawed investigative designs or problems with methodology. Some results may be incorrect because of reliance on time-aggregated data collected during a period of changing atmospheric emissions. None of the investigations used methods that could accurately quantify the part of highway runoff load that can be attributed to ambient atmospheric deposition. Lack of information about accurate ambient deposition rates and runoff loads was part of the problem. Samples collected to compute the rates and loads were collected without clean-sampling methods or sampler protocols, and without quality-assurance procedures that could validate the data. Massbudget calculations comparing deposition and runoff did not consider loss of deposited material during on-highway processing. Loss of deposited particles from highway travel lanes could be large, as has been determined in labeled particle studies, because of resuspension caused by turbulence from passing traffic. Although a cause of resuspension of large particles, traffic turbulence may increase the rate of deposition for small particles and

  11. Dust resuspension without saltation

    PubMed Central

    Loosmore, Gwen A.; Hunt, James R.

    2010-01-01

    Wind resuspension (or entrainment) provides a source of dust and contaminants for the atmosphere. Conventional wind erosion models parameterize dust resuspension flux with a threshold velocity or with a horizontal abrasion flux; in the absence of abrasion the models assume dust flux is transient only. Our experiments with an uncrusted, fine material at relative humidities exceeding 40% show a long-term steady dust flux in the absence of abrasion, which fits the approximate form: Fd = 3.6(u*)3, where Fd is the dust flux (in μg/m2 s), and u* is the friction velocity (in m/s). These fluxes are generally too small to be significant sources of dust in most models of dust emission. However, they provide a potential route to transport contaminants into the atmosphere. In addition, dust release is substantial during the initial transient phase. Comparison with field data suggests that the particle friction Reynolds number may prove a better parameter than u* for correlating fluxes and understanding the potential for abrasion. PMID:20336175

  12. ATMOSPHERIC DEPOSITION MODELING AND MONITORING OF NUTRIENTS

    EPA Science Inventory

    This talk presents an overview of the capabilities and roles that regional atmospheric deposition models can play with respect to multi-media environmental problems. The focus is on nutrient deposition (nitrogen). Atmospheric deposition of nitrogen is an important contributor to...

  13. Atmospheric deposition to high-elevation forests

    SciTech Connect

    Lovett, G.M.; Weathers, K.C.; Lindberg, S.E. Oak Ridge National Lab., TN )

    1994-06-01

    Three important phenomena characterize atmospheric deposition to high-elevation forests: (1) multiple deposition mechanisms (wet, dry, and cloud deposition), (2) high rates of deposition, and (3) high spatial variability. The high rates of deposition are caused by changes in meteorological conditions with elevation, especially increasing wind speed and cloud immersion frequency. The high spatial variability of deposition is a result of the regulation of cloud and dry deposition rates by microclimatic and canopy structure conditions, which can be extremely heterogeneous in mountain landscapes. Spruce-fir forests are often [open quotes]hot spots[close quotes] of deposition when viewed in a landscape or regional context because of their elevation, exposure, and evergreen canopy. In this talk we will consider atmospheric depositions to high-elevation forests in both the northeastern and southeastern U.S., using field data and geographic information systems to illustrate deposition patterns.

  14. Resuspension and atmospheric transport of radionuclides due to wildfires near the Chernobyl Nuclear Power Plant in 2015: An impact assessment

    NASA Astrophysics Data System (ADS)

    Evangeliou, N.; Zibtsev, S.; Myroniuk, V.; Zhurba, M.; Hamburger, T.; Stohl, A.; Balkanski, Y.; Paugam, R.; Mousseau, T. A.; Møller, A. P.; Kireev, S. I.

    2016-05-01

    In April and August 2015, two major fires in the Chernobyl Exclusion Zone (CEZ) caused concerns about the secondary radioactive contamination that might have spread over Europe. The present paper assessed, for the first time, the impact of these fires over Europe. About 10.9 TBq of 137Cs, 1.5 TBq of 90Sr, 7.8 GBq of 238Pu, 6.3 GBq of 239Pu, 9.4 GBq of 240Pu and 29.7 GBq of 241Am were released from both fire events corresponding to a serious event. The more labile elements escaped easier from the CEZ, whereas the larger refractory particles were removed more efficiently from the atmosphere mainly affecting the CEZ and its vicinity. During the spring 2015 fires, about 93% of the labile and 97% of the refractory particles ended in Eastern European countries. Similarly, during the summer 2015 fires, about 75% of the labile and 59% of the refractory radionuclides were exported from the CEZ with the majority depositing in Belarus and Russia. Effective doses were above 1 mSv y‑1 in the CEZ, but much lower in the rest of Europe contributing an additional dose to the Eastern European population, which is far below a dose from a medical X-ray.

  15. Resuspension and atmospheric transport of radionuclides due to wildfires near the Chernobyl Nuclear Power Plant in 2015: An impact assessment

    PubMed Central

    Evangeliou, N.; Zibtsev, S.; Myroniuk, V.; Zhurba, M.; Hamburger, T.; Stohl, A.; Balkanski, Y.; Paugam, R.; Mousseau, T. A.; Møller, A. P.; Kireev, S. I.

    2016-01-01

    In April and August 2015, two major fires in the Chernobyl Exclusion Zone (CEZ) caused concerns about the secondary radioactive contamination that might have spread over Europe. The present paper assessed, for the first time, the impact of these fires over Europe. About 10.9 TBq of 137Cs, 1.5 TBq of 90Sr, 7.8 GBq of 238Pu, 6.3 GBq of 239Pu, 9.4 GBq of 240Pu and 29.7 GBq of 241Am were released from both fire events corresponding to a serious event. The more labile elements escaped easier from the CEZ, whereas the larger refractory particles were removed more efficiently from the atmosphere mainly affecting the CEZ and its vicinity. During the spring 2015 fires, about 93% of the labile and 97% of the refractory particles ended in Eastern European countries. Similarly, during the summer 2015 fires, about 75% of the labile and 59% of the refractory radionuclides were exported from the CEZ with the majority depositing in Belarus and Russia. Effective doses were above 1 mSv y−1 in the CEZ, but much lower in the rest of Europe contributing an additional dose to the Eastern European population, which is far below a dose from a medical X-ray. PMID:27184191

  16. Resuspension and atmospheric transport of radionuclides due to wildfires near the Chernobyl Nuclear Power Plant in 2015: An impact assessment.

    PubMed

    Evangeliou, N; Zibtsev, S; Myroniuk, V; Zhurba, M; Hamburger, T; Stohl, A; Balkanski, Y; Paugam, R; Mousseau, T A; Møller, A P; Kireev, S I

    2016-01-01

    In April and August 2015, two major fires in the Chernobyl Exclusion Zone (CEZ) caused concerns about the secondary radioactive contamination that might have spread over Europe. The present paper assessed, for the first time, the impact of these fires over Europe. About 10.9 TBq of (137)Cs, 1.5 TBq of (90)Sr, 7.8 GBq of (238)Pu, 6.3 GBq of (239)Pu, 9.4 GBq of (240)Pu and 29.7 GBq of (241)Am were released from both fire events corresponding to a serious event. The more labile elements escaped easier from the CEZ, whereas the larger refractory particles were removed more efficiently from the atmosphere mainly affecting the CEZ and its vicinity. During the spring 2015 fires, about 93% of the labile and 97% of the refractory particles ended in Eastern European countries. Similarly, during the summer 2015 fires, about 75% of the labile and 59% of the refractory radionuclides were exported from the CEZ with the majority depositing in Belarus and Russia. Effective doses were above 1 mSv y(-1) in the CEZ, but much lower in the rest of Europe contributing an additional dose to the Eastern European population, which is far below a dose from a medical X-ray. PMID:27184191

  17. Atmospheric deposition maps for the Rocky Mountains

    USGS Publications Warehouse

    Nanus, L.; Campbell, D.H.; Ingersoll, G.P.; Clow, D.W.; Mast, M.A.

    2003-01-01

    Variability in atmospheric deposition across the Rocky Mountains is influenced by elevation, slope, aspect, and precipitation amount and by regional and local sources of air pollution. To improve estimates of deposition in mountainous regions, maps of average annual atmospheric deposition loadings of nitrate, sulfate, and acidity were developed for the Rocky Mountains by using spatial statistics. A parameter-elevation regressions on independent slopes model (PRISM) was incorporated to account for variations in precipitation amount over mountainous regions. Chemical data were obtained from the National Atmospheric Deposition Program/National Trends Network and from annual snowpack surveys conducted by the US Geological Survey and National Park Service, in cooperation with other Federal, State and local agencies. Surface concentration maps were created by ordinary kriging in a geographic information system, using a local trend and mathematical model to estimate the spatial variance. Atmospheric-deposition maps were constructed at 1-km resolution by multiplying surface concentrations from the kriged grid and estimates of precipitation amount from the PRISM model. Maps indicate an increasing spatial trend in concentration and deposition of the modeled constituents, particularly nitrate and sulfate, from north to south throughout the Rocky Mountains and identify hot-spots of atmospheric deposition that result from combined local and regional sources of air pollution. Highest nitrate (2.5-3.0kg/ha N) and sulfate (10.0-12.0kg/ha SO4) deposition is found in northern Colorado.

  18. ATMOSPHERIC ACID DEPOSITION DAMAGE TO PAINTS

    EPA Science Inventory

    Available data from laboratory and field studies of damage to paints by erosion have been analyzed to develop an atmospheric acid deposition damage function for exterior house paints containing calcium carbonate or silicate extenders. Regression analysis coefficients associated w...

  19. ASSESSMENT OF ATMOSPHERIC DEPOSITION ECOLOGICAL IMPACTS

    EPA Science Inventory

    CAMD works with research scientists and organizations in the academic community to assess and better understand the impacts of atmospheric deposition of power sector pollutant emissions on terrestrial and aquatic (including freshwater and marine) ecosystems. See peer review pr...

  20. Study of dust re-suspension at low pressure in a dedicated wind-tunnel

    NASA Astrophysics Data System (ADS)

    Rondeau, Anthony; Sabroux, Jean-Christophe; Chassefière, Eric

    2015-04-01

    The atmosphere of several telluric planets or satellites are dusty. Such is the case of Earth, Venus, Mars and Titan, each bearing different aeolian processes linked principally to the kinematic viscosity of the near-surface atmosphere. Studies of the Martian atmosphere are particularly relevant for the understanding of the dust re-suspension phenomena at low pressure (7 mbar). It turns out that operation of fusion reactors of the tokamak design produces significant amount of dust through the erosion of plasma-facing components. Such dust is a key issue, both regarding the performance and the safety of a fusion reactor such as ITER, under construction in Cadarache, France. Indeed, to evaluate the explosion risk in the ITER fusion reactor, it is essential to quantify the re-suspended dust fraction as a function of the dust inventory that can be potentially mobilized during a loss of vacuum accident (LOVA), with air or water vapour ingress. A complete accident sequence will encompass dust re-suspension from near-vacuum up to atmospheric pressure. Here, we present experimental results of particles re-suspension fractions measured at 1000, 600 and 300 mbar in the IRSN BISE (BlowIng facility for airborne releaSE) wind tunnel. Both dust monolayer deposits and multilayer deposits were investigated. In order to obtain experimental re-suspension data of dust monolayer deposits, we used an optical microscope allowing to measure the re-suspended particles fraction by size intervals of 1 µm. The deposits were made up of tungsten particles on a tungsten surface (an ubiquitous plasma facing component) and alumina particles on a glass plate, as a surrogate. A comparison of the results with the so-called Rock'nRoll dust re-suspension model (Reeks and Hall, 2001) is presented and discussed. The multilayer deposits were made in a vacuum sedimentation chamber allowing to obtain uniform deposits in terms of thickness. The re-suspension experimental data of such deposits were obtained

  1. Radionuclides in the terrestrial ecosystem near a Canadian uranium mill -- Part 3: Atmospheric deposition rates (pilot test)

    SciTech Connect

    Thomas, P.A.

    2000-06-01

    Atmospheric deposition rates of uranium series radionuclides were directly measured at three sites near the operating Key Lake uranium mill in northern Saskatchewan. Sites impacted by windblown tailings and mill dusts had elevated rates of uranium deposition near the mill and elevated {sup 226}Ra deposition near the tailings compared to a control site. Rainwater collectors, dust jars, and passive vinyl collectors previously used at the Ranger Mine in Australia were pilot-tested. Adhesive vinyl surfaces (1 m{sup 2}) were oriented horizontally, vertically, and facing the ground as a means of measuring gravitational settling, wind impaction, and soil resuspension, respectively. Although the adhesive glue on the vinyls proved difficult to digest, relative differences in deposition mode were found among radionuclides and among sites. Dry deposition was a more important transport mechanism for uranium, {sup 226}Ra, and {sup 210}Pb than rainfall, while more {sup 210}Po was deposited with rainfall.

  2. Modeling atmospheric concentrations and deposition of Hg

    SciTech Connect

    Shannon, J.D.

    1994-06-01

    The deleterious effects on ecosystems of mercury pollution are well established and fish advisories are in effect for many lakes in North America. Because methylation and other transformation processes in ecosystems can alter the original speciation of deposited Hg, a decrease in atmospheric loading of Hg in all forms is highly desirable. The contribution to Hg deposition by emissions from current anthropogenic activities relative to the deposition contribution by emissions from natural processes must be estimated to establish what fraction of atmospheric loading to watersheds and ecosystems is at least potentially amenable to control actions. Additional modeling questions concern source-receptor relationships (SRR) for major point sources and for emissions aggregated over geopolitical regions or emission sectors, because of the usefulness of SRR in comparing effectiveness of alternate control strategies. Modeling of atmospheric Hg is less advanced than that of some other widespread air pollution problems such as acid deposition. Nonetheless, several promising studies have been made for northern Europe and North America. For this study of Hg deposition in eastern North America we extend modeling techniques used extensively and successfully during the last 15 years for concentrations and deposition of SO{sub x} and NO{sub x} over regional scales, with parameterization rates adjusted to suitable values for Hg transformation and removal.

  3. Pacific Northwest Laboratory annual report for 1982 to the DOE Office of Energy Research. Part 3. Atmospheric sciences

    SciTech Connect

    Elderkin, C.E.

    1983-02-01

    This report is organized in terms of generic studies: theoretical studies of atmospheric processes; pollutant characterizations and transformation; boundary layer meteorology; and dispersion, deposition and resuspension of atmospheric pollutants.

  4. Forecasting volcanic ash dispersal and coeval resuspension during the April-May 2015 Calbuco eruption

    NASA Astrophysics Data System (ADS)

    Reckziegel, F.; Bustos, E.; Mingari, L.; Báez, W.; Villarosa, G.; Folch, A.; Collini, E.; Viramonte, J.; Romero, J.; Osores, S.

    2016-07-01

    Atmospheric dispersion of volcanic ash from explosive eruptions or from subsequent fallout deposit resuspension causes a range of impacts and disruptions on human activities and ecosystems. The April-May 2015 Calbuco eruption in Chile involved eruption and resuspension activities. We overview the chronology, effects, and products resulting from these events, in order to validate an operational forecast strategy for tephra dispersal. The modelling strategy builds on coupling the meteorological Weather Research and Forecasting (WRF/ARW) model with the FALL3D dispersal model for eruptive and resuspension processes. The eruption modelling considers two distinct particle granulometries, a preliminary first guess distribution used operationally when no field data was available yet, and a refined distribution based on field measurements. Volcanological inputs were inferred from eruption reports and results from an Argentina-Chilean ash sample data network, which performed in-situ sampling during the eruption. In order to validate the modelling strategy, results were compared with satellite retrievals and ground deposit measurements. Results indicate that the WRF-FALL3D modelling system can provide reasonable forecasts in both eruption and resuspension modes, particularly when the adjusted granulometry is considered. The study also highlights the importance of having dedicated datasets of active volcanoes furnishing first-guess model inputs during the early stages of an eruption.

  5. MEAD Marine Effects of Atmospheric Deposition

    NASA Astrophysics Data System (ADS)

    Jickells, T.; Spokes, L.

    2003-04-01

    The coastal seas are one of the most valuable resources on the planet but they are threatened by human activity. We rely on the coastal area for mineral resources, waste disposal, fisheries and recreation. In Europe, high population densities and high levels of industrial activity mean that the pressures arising from these activities are particularly acute. One of the main problems concerning coastal seas is the rapid increase in the amounts of nitrogen-based pollutants entering the water. They come from many sources, the most important ones being traffic, industry and agriculture. These pollutants can be used by algae as nutrients. The increasing concentrations of these nutrients have led to excessive growth of algae, some of which are harmful. When algae die and decay, oxygen in the water is used up and the resulting lower levels of oxygen may lead to fish kills. Human activity has probably doubled the amount of chemically and biologically reactive nitrogen present globally. In Europe the increases have been greater than this, leading to real concern over the health of coastal waters. Rivers have, until recently, been thought to be the most important source of reactive nitrogen to the coastal seas but we now know that inputs from the atmosphere are large and can equal, or exceed, those from the rivers. Our initial hypothesis was that atmospheric inputs are important and potentially different in their effect on coastal ecosystems to riverine inputs and hence require different management strategies. However, we had almost no information on the direct effects of atmospheric deposition on marine ecosystems, though clearly such a large external nitrogen input should lead to enhanced phytoplankton growth The aim of this European Union funded MEAD project has been to determine how inputs of nitrogen from the atmosphere affect the chemistry and biology of coastal waters. To try to answer this, we have conducted field experiments in the Kattegat, an area where we know

  6. Atmospheric deposition fluxes to Monetary Bay

    NASA Astrophysics Data System (ADS)

    Gray, E.; Paytan, A.; Ryan, J.

    2008-12-01

    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. Sources of these components include both natural (volcanoes, mineral dust, forest fires) and anthropogenic (fossil fuels, chemical byproducts, incineration of waste) sources, which may contribute to harmful health and environmental impacts such as eutrophication, contaminated fish and harmful algal blooms. This study looks at the flux of aerosol deposition (TSP - total suspended particle load) to Monterey Bay, California. Samples are collected on a cascade impactor aerosol sampler (size fractions PM 2.5 and PM 10) every 48 hours continuously. Preliminary results indicate that the TSP for PM 10 ranged from 0.026 to 0.104 mg m-3 of air and for PM 2.5 from 0.014 to 0.046 mg m-3 of air. Using a deposition velocity of 2 cm s-1 for the large fraction (PM10 - PM 2.5) and a deposition velocity of 0.7 cm s-1 for the fine fraction (PM 2.5) deposition rates are 13 and 86 mg m-2 d-1 respectively.

  7. Alkylphenols in atmospheric depositions and urban runoff.

    PubMed

    Bressy, A; Gromaire, M-C; Lorgeoux, C; Chebbo, G

    2011-01-01

    A sampling campaign was conducted in order to determine alkylphenol (AP) concentrations in stormwater as well as potential AP sources in suburban environments. An analytical procedure was developed to quantify APs in bulk atmospheric deposition, building runoff, road runoff and stormwater. Both nonylphenols and octylphenols could be quantified in each sample. Median stormwater concentrations amounted to: 470 ng/l for nonylphenols, and 36 ng/l for octylphenols. These concentrations are 3 times higher than those found in atmospheric deposition, thus proving that local human activity constitutes a significant source of contamination. The contributions of the various sources to stormwater have been assessed from mass balances at the catchment scale. 70% of AP mass in stormwater originates from building and road emissions. Annual AP fluxes have been extrapolated from the total AP mass measured over our sampling periods for atmospheric depositions (44 to 84 µgNP/m(2)/yr) and stormwater (100 to 190 µgNP/m(2)/yr). Moreover, since APs were mainly found in the dissolved fraction, runoff treatment devices based on settling are unlikely to be very efficient. PMID:21330713

  8. Modeling Atmospheric Energy Deposition (by energetic ions)

    NASA Astrophysics Data System (ADS)

    Parkinson, C. D.; Brain, D. A.; Lillis, R. J.; Liemohn, M. W.; Bougher, S. W.

    2011-12-01

    The structure, dynamics, chemistry, and evolution of planetary upper atmospheres are in large part determined by the available sources of energy. In addition to the solar EUV flux, the solar wind and solar energetic particle (SEP) events are also important sources. Both of these particle populations can significantly affect an atmosphere, causing atmospheric loss and driving chemical reactions. Attention has been paid to these sources from the standpoint of the radiation environment for humans and electronics, but little work has been done to evaluate their impact on planetary atmospheres. At unmagnetized planets or those with crustal field anomalies, in particular, the solar wind and SEPs of all energies have direct access to the atmosphere and so provide a more substantial energy source than at planets having protective global magnetic fields. Additionally, solar wind and energetic particle fluxes should be more significant for planets orbiting more active stars, such as is the case in the early history of the solar system for paleo-Venus and Mars. Therefore quantification of the atmospheric energy input from the solar wind and SEP events is an important component of our understanding of the processes that control their state and evolution. Such modeling has been previously done for Earth, Mars and Jupiter using a guiding center precipitation model with extensive collisional physics. Currently, this code is only valid for particles with small gyroradii in strong uniform magnetic fields. There is a clear necessity for a Lorentz formulation that can perform calculations for cases where there is only a weak or nonexistent magnetic field that includes detailed physical interaction with the atmosphere (i.e. collisional physics). We show initial efforts to apply a full Lorentz motion particle transport model to study the effects of particle precipitation in the upper atmospheres of Venus, Mars, and Titan. A systematic study of the ionization, excitation, and energy

  9. Resuspension of small particles from tree surfaces

    NASA Astrophysics Data System (ADS)

    Ould-Dada, Zitouni; Baghini, Nasser M.

    A detailed study of resuspension of 1.85 μm MMAD silica particles from five horizontal layers within a small scale spruce canopy was carried out in a wind tunnel in which saplings were exposed to a constant free stream wind speed of 5 m s -1. This provided quantitative estimates of the potential for a tree canopy contaminated with an aerosol deposit to provide (i) an airborne inhalation hazard within the forest environment and (ii) a secondary source of airborne contamination after an initial deposition event. Resuspension occurred with a flux of 1.05×10 -7 g m -2 s -1 from spruce saplings initially contaminated at a level of 4.1×10 -2 g m -2. An average resuspension rate ( Λ) of 4.88×10 -7 s -1 was obtained for the canopy as a whole. Values of Λ were significantly different (ANOVA, p<0.001) between canopy layers and Λ was markedly greater at the top of the canopy than lower down although there was a slight increase in Λ at the base of the canopy. The resuspended silica particles deposited onto the soil surface at an average rate of about 5.3×10 -8 μg cm -2 s -1. It is concluded that resuspension under wind velocities similar to that used in the reported experiments is likely to pose a relatively small inhalation hazard to humans and a relatively minor source of secondary contamination of adjacent areas. Furthermore, resuspension rates are likely to diminish rapidly with time. The results are discussed in relation to the growing interest in the tree planting schemes in urban areas to reduce the impacts of air pollution.

  10. Simple Approaches for Measuring Dry Atmospheric Nitrogen Deposition to Watersheds

    EPA Science Inventory

    Assessing the effects of atmospheric nitrogen (N) deposition on surface water quality requires accurate accounts of total N deposition (wet, dry, and cloud vapor); however, dry deposition is difficult to measure and is often spatially variable. Affordable passive sampling methods...

  11. Uncertainty of the long-term resuspension factor

    NASA Astrophysics Data System (ADS)

    Garger, Evgenii K.; Hoffman, F. Owen; Thiessen, Kathleen M.

    Resuspension of contaminated soil into the atmosphere is one of the key processes that must be considered in the estimation of inhalation doses to humans. Data for air and soil contamination collected in Ukraine over several years since the Chernobyl accident have permitted analysis of resuspension in terms of the underlying mechanisms. Various empirical models for the resuspension factor as a function of time (e.g. Linsley, Garland, Anspaugh, etc.) are compared to the observed resuspension factors over time (9 yr) at two sites; in general, these models give overestimates for the resuspension factor as a function of time. The observed values of the resuspension factor range from greater than 10 -5 m -1 at early time points to around 10 -10 m -1 at later points. The uncertainty in the resuspension factor is decreased to within 1 order of magnitude if annual averaging of the experimental data is used and if the resuspension factor is determined as a function of time and of the predominant regional conditions of vegetative cover and climate.

  12. Simple estimates of vehicle-induced resuspension rates.

    PubMed

    Escrig, A; Amato, F; Pandolfi, M; Monfort, E; Querol, X; Celades, I; Sanfélix, V; Alastuey, A; Orza, J A G

    2011-10-01

    Road dust emissions are considered to be a major source of airborne particulate matter (PM). This is particularly true for industrial environments, where there are high resuspension rates of deposited dust. The calculation of roads as PM emission sources has mostly focused on the consequences of this emission, viz. the increase in PM concentrations. That approach addresses the atmospheric transport of the emitted dust, and not its primary origin. In contrast, this paper examines the causes of the emission. The study is based on mass conservation of the dust deposited on the road surface. On the basis of this premise, estimates of emission rates were calculated from experimental data obtained in a road in a ceramic industrial area. PMID:21763062

  13. Energy Deposition Processes in Titan's Upper Atmosphere

    NASA Technical Reports Server (NTRS)

    Sittler, Edward C., Jr.; Bertucci, Cesar; Coates, Andrew; Cravens, Tom; Dandouras, Iannis; Shemansky, Don

    2008-01-01

    Most of Titan's atmospheric organic and nitrogen chemistry, aerosol formation, and atmospheric loss are driven from external energy sources such as Solar UV, Saturn's magnetosphere, solar wind and galactic cosmic rays. The Solar UV tends to dominate the energy input at lower altitudes of approximately 1100 km but which can extend down to approximately 400 km, while the plasma interaction from Saturn's magnetosphere, Saturn's magnetosheath or solar wind are more important at higher altitudes of approximately 1400 km, but the heavy ion plasma [O(+)] of approximately 2 keV and energetic ions [H(+)] of approximately 30 keV or higher from Saturn's magnetosphere can penetrate below 950km. Cosmic rays with energies of greater than 1 GeV can penetrate much deeper into Titan's atmosphere with most of its energy deposited at approximately 100 km altitude. The haze layer tends to dominate between 100 km and 300 km. The induced magnetic field from Titan's interaction with the external plasma can be very complex and will tend to channel the flow of energy into Titan's upper atmosphere. Cassini observations combined with advanced hybrid simulations of the plasma interaction with Titan's upper atmosphere show significant changes in the character of the interaction with Saturn local time at Titan's orbit where the magnetosphere displays large and systematic changes with local time. The external solar wind can also drive sub-storms within the magnetosphere which can then modify the magnetospheric interaction with Titan. Another important parameter is solar zenith angle (SZA) with respect to the co-rotation direction of the magnetospheric flow. Titan's interaction can contribute to atmospheric loss via pickup ion loss, scavenging of Titan's ionospheric plasma, loss of ionospheric plasma down its induced magnetotail via an ionospheric wind, and non-thermal loss of the atmosphere via heating and sputtering induced by the bombardment of magnetospheric keV ions and electrons. This

  14. A review of particle resuspension

    NASA Astrophysics Data System (ADS)

    Nicholson, K. W.

    Some of the various types of studies on particle resuspension or re-entrainment are summarized along with shortcomings. General experimental aspects have been considered, rather than focusing on the numerical values of results, and research on erosion and resuspension by mechanisms other than wind has been included. It is evident that experiments have been performed in a wide range of environmental conditions but that additional research is required, in many areas, if a quantitative assessment of resuspension is to be achieved.

  15. Evaluation of atmospheric PCDD/F depositions via automated and traditional water surface samplers in Taiwan.

    PubMed

    Chi, Kai Hsien; Kao, Shuh Ji; Liu, Kung Ting; Lee, Tzu Yi

    2012-03-01

    Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) are a group of compounds of major environmental concern. Once emitted into the atmosphere, PCDD/Fs undergo photochemical reactions and enter other environmental compartments via wet and dry deposition. In this study, atmospheric PCDD/F depositions were collected via an automated PCDD/F deposition sampler and traditional cylindrical vessels, respectively, in northern, central, and southern Taiwan from 2008 to 2010. The automated PCDD/F precipitation sampler used in this study can prevent both resuspension and photodegradation of the PCDD/Fs collected and also effectively separates the PCDD/F samples into dry and wet contributions. The results indicate that the average atmospheric PCDD/F concentrations collected by the high-volume sampling trains were 13.6 ± 10 (n = 10), 15.6 ± 5.2 (n = 7), and 10.9 ± 6.3 (n = 6) fg I-TEQ/m(3) in northern, central, and southern Taiwan, respectively. In addition, the results also indicate that the PCDD/F deposition flux collected with an automated PCDD/F sampler (1.84 ± 0.90-8.68 ± 5.1 pg I-TEQ/m(2)/day, n = 23) is significantly higher than that sampled with cylindrical vessels (1.11 ± 0.69-5.64 ± 5.2 pg I-TEQ/m(2)/day, n = 23). Based on the Mann-Whitney statistical analysis, the p value (0.037) of PCDD/F deposition flux between those two samplers measurement is lower than 0.05. The difference is attributed to the fact that part of the PCDD/F depositions collected by traditional cylindrical vessels is photodegraded and revolatilized. In addition, the wet deposition flux of PCDD/Fs (3.66 to 470 pg I-TEQ/m(2)/rainy day, n = 23) observed in Taiwan is significantly higher than the dry deposition flux (0.38 to 4.55 pg I-TEQ/m(2)/sunny day, n = 23). The results demonstrate that the wet deposition is the major PCDD/F removal mechanism in the atmosphere. Furthermore, the overall PCDD/Fs deposition velocity and scavenging (rainout) coefficient in Taiwan are calculated as 0

  16. Time dependence of the {sup 137}Cs resuspension factor on the Romanian territory after the Chernobyl accident

    SciTech Connect

    Mihaila, B.; Cuculeanu, V.

    1994-08-01

    On the basis of the radioactivity levels in aerosol and atmospheric deposition samples due to the Chernobyl accident, the resuspension factor of {sup 137}Cs as a four-parameter function has been inferred. The standard procedure to derive the dependence of resuspension on time assumes that the initial deposit is instantaneous. A simple method assuming a constant deposition rate over a fixed period has been proposed. Also, based on existing experimental data, an attempt was made to consider a realistic time dependence of the deposition rate to cope with the particular case of the Chernobyl accident. The differences between the two models are outlined. The Chernobyl direct deposit has been assumed to be the deposit measured between 30 April and 30 June 1986. The calculated values of the resuspension factor are consistent with the IAEA`s recommended model and depend on the rainfall that occurred in June 1986 and the site-specific disturbance conditions during the first 100 d following 1 July 1986 and only on artificial disturbance by humans and vehicles after that. 16 refs., 5 figs., 3 tabs.

  17. An improved model for prediction of resuspension.

    PubMed

    Maxwell, Reed M; Anspaugh, Lynn R

    2011-12-01

    A complete, historical dataset is presented of radionuclide resuspension-factors. These data span six orders of magnitude in time (ranging from 0.1 to 73,000 d), encompass more than 300 individual values, and combine observations from events on three continents. These data were then used to derive improved, empirical models that can be used to predict resuspension of trace materials after their deposit on the ground. Data-fitting techniques were used to derive models of various types and an estimate of uncertainty in model prediction. Two models were found to be suitable: a power law and the modified Anspaugh et al. model, which is a double exponential. Though statistically the power-law model provides the best metrics of fit, the modified Anspaugh model is deemed the more appropriate due to its better fit to data at early times and its ease of implementation in terms of closed analytical integrals. PMID:22048490

  18. Local and Regional Influences on Atmospheric Nutrient Deposition in Southeast Brazil

    NASA Astrophysics Data System (ADS)

    Allen, A. G.; Machado, C. M.; Cardoso, A. A.

    2009-05-01

    The objective of this work was to quantify sources of atmospheric nutrients, which are subsequently deposited to agricultural soils and natural ecosystems of São Paulo State (Brazil). The atmospheric concentrations of soluble ions (NO3-, NH4+, PO43-, SO42-, Cl-, K+, Na+, Mg2+ and Ca2+) in aerosol were evaluated, together with the gases NO2, NH3, HNO3 and SO2. Identification of nutrient sources was achieved using principal component analysis (PCA) followed by multiple linear regression analysis (MLRA). Dry deposition fluxes were estimated using the measured atmospheric concentrations together with dry deposition velocities of gases and aerosols to different surface types. Results showed that the main sources of nutrients to the regions atmosphere were fossil and biofuel combustion (N and S species), agricultural biomass burning (N, S, K and P), re-suspension of soils and dusts (Ca and Mg), and to a lesser extent long-range transport (S). NO2 concentrations were more influenced by local emissions and subsequent chemical transformations occurring on a scale of up to 200-300 km. HNO3 was much less spatially variable, with consistently higher concentrations during warmer, drier periods, indicating an agreement with gas phase/aerosol phase thermodynamic equilibrium theory. Scavenging of gaseous HNO3 was a source of nitrate, for which deposition fluxes were higher during the dry season, when significant relationships were obtained between nitrate concentrations and biomass burning intensity. Additional sources were indicated for particulate nitrate and sulphate, such as road transport and secondary reactions. During winter, the main source of gaseous ammonia was biomass burning, while emissions from soils and wastes predominated during summer. Modeled deposition fluxes were highest to tropical forest and lowest to water and pasture surfaces. In agricultural areas, the deposition fluxes of aerosol components N, P and K (0.37, 0.029 and 0.59 kg ha-1 yr-1, respectively

  19. Atmospheric deposition of PCDD/Fs measured via automated and traditional samplers in Northern Taiwan.

    PubMed

    Chi, Kai Hsien; Liu, Kung Ting; Chang, Shu Hao; Chang, Moo Been

    2009-11-01

    Most polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in the atmosphere are bound to particles which are suspended in the atmosphere, and eventually settle on soil, vegetation, water bodies or other receptors in the environment. Monitoring atmospheric deposition fluxes (dry/wet) is important in tracing the environmental fate and behavior of PCDD/Fs. PCDD/F depositions were collected via an automated PCDD/F ambient sampler and traditional cylindrical vessels, respectively, from April 2007 to February 2008. The automated PCDD/F ambient sampler used in this study can prevent both re-suspension and photo degradation of the PCDD/Fs collected and effectively separates the PCDD/F samples into dry and wet contributions. The results indicated that the ambient PCDD/F concentrations collected using the PS-1 sampler ranged from 0.02 pg I-TEQ/m(3) to 0.16 pg I-TEQ/m(3) in Northern Taiwan. The results also indicated that the PCDD/F deposition flux collected using the automated PCDD/F sampler (17.5 pg I-TEQ/m(2) d to 25.8 pg I-TEQ/m(2) d) was significantly higher than that sampled with the cylindrical vessels (2.0 pg I-TEQ/m(2) d to 9.9 pg I-TEQ/m(2) d). The difference was attributed to the fact that part of the PCDD/F depositions collected using the traditional cylindrical vessels had undergone photo degradation and evaporation. In addition, the wet deposition flux of PCDD/Fs (39.4 pg I-TEQ/m(2) rainy day to 228 pg I-TEQ/m(2) rainy day) observed in this study was significantly higher than the dry deposition flux (12.3 pg I-TEQ/m(2) sunny day to 16.7 pg I-TEQ/m(2) sunny day). These results demonstrated that wet deposition is the major PCDD/F removal mechanism in the atmosphere. PMID:19819518

  20. ULTRASONIC MEASUREMENT OF SEDIMENT RESUSPENSION

    EPA Science Inventory

    Recognizing the need for improved measurement and parameterization of sediment resuspension, this paper presents a review of the major methods now in use for alleviating this need. Special attention is devoted to reviewing methods for obtaining sediment concentration profiles by ...

  1. Sampling of Atmospheric Precipitation and Deposits for Analysis of Atmospheric Pollution

    PubMed Central

    Skarżyńska, K.; Polkowska, Ż; Namieśnik, J.

    2006-01-01

    This paper reviews techniques and equipment for collecting precipitation samples from the atmosphere (fog and cloud water) and from atmospheric deposits (dew, hoarfrost, and rime) that are suitable for the evaluation of atmospheric pollution. It discusses the storage and preparation of samples for analysis and also presents bibliographic information on the concentration ranges of inorganic and organic compounds in the precipitation and atmospheric deposit samples. PMID:17671615

  2. THE WATERSHED DEPOSITION TOOL: A MEANS TO LINK ATMOSPHERIC DEPOSITION TO WATERSHEDS

    EPA Science Inventory

    The potential for atmospheric deposition reductions to contribute to water quality management is not being included in many planning exercises. This is because often the water quality scientists do not know where to get and how to use projections of atmospheric deposition reducti...

  3. ATMOSPHERIC TRANSPORT AND DEPOSITION OF AGRICULTURAL PESTICIDES TO SENSITIVE ECOSYSTEMS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Off-site transport of pesticides from the point of application may occur by runoff to surface waters, leaching into sub-soil layers and groundwater, and via volatilization to the atmosphere. Atmospheric transport and subsequent deposition of pesticides may negatively affect sensitive wildlife speci...

  4. Atmospheric iron deposition: global distribution, variability, and human perturbations.

    PubMed

    Mahowald, Natalie M; Engelstaedter, Sebastian; Luo, Chao; Sealy, Andrea; Artaxo, Paulo; Benitez-Nelson, Claudia; Bonnet, Sophie; Chen, Ying; Chuang, Patrick Y; Cohen, David D; Dulac, Francois; Herut, Barak; Johansen, Anne M; Kubilay, Nilgun; Losno, Remi; Maenhaut, Willy; Paytan, Adina; Prospero, Joseph M; Shank, Lindsey M; Siefert, Ronald L

    2009-01-01

    Atmospheric inputs of iron to the open ocean are hypothesized to modulate ocean biogeochemistry. This review presents an integration of available observations of atmospheric iron and iron deposition, and also covers bioavailable iron distributions. Methods for estimating temporal variability in ocean deposition over the recent past are reviewed. Desert dust iron is estimated to represent 95% of the global atmospheric iron cycle, and combustion sources of iron are responsible for the remaining 5%. Humans may be significantly perturbing desert dust (up to 50%). The sources of bioavailable iron are less well understood than those of iron, partly because we do not know what speciation of the iron is bioavailable. Bioavailable iron can derive from atmospheric processing of relatively insoluble desert dust iron or from direct emissions of soluble iron from combustion sources. These results imply that humans could be substantially impacting iron and bioavailable iron deposition to ocean regions, but there are large uncertainties in our understanding. PMID:21141037

  5. [Characteristics of atmospheric nitrogen wet deposition in Beijing urban area].

    PubMed

    He, Cheng-Wu; Ren, Yu-Fen; Wang, Xiao-Ke; Mao, Yu-Xiang

    2014-02-01

    With the ion-exchange resin method, the atmospheric nitrogen wet deposition in Beijing urban area within the Fifth Ring Road was investigated from June to October, 2012. The relationship between atmospheric nitrogen wet deposition and rainfall precipitation was investigated, the differences of nitrogen wet deposition in different months, different ring roads (the Fifth Ring Road, the Fourth Ring Road, the Third Ring Road and the Second Ring Road) and different functional areas (institutes and colleges district, ring-road, residential areas, railway station and public garden) were also investigated. The results showed that the average value and standard deviation of ammonia-nitrogen, nitrate-nitrogen and nitrite-nitrogen were significantly different during different months in 2012. The atmospheric nitrite nitrogen deposition first decreased and then increased, the maximum value appeared in September. The positive relationships between ammonia nitrogen (nitrate nitrogen) and mean monthly precipitation and negative relationships between nitrite nitrogen and mean monthly precipitation were both significant (P < 0.05). The three nitrogen depositions of ring-road and railway station were higher than other functional areas, but only the nitrite nitrogen deposition had obvious regional difference. The differences of the three nitrogen depositions among different ring roads were all not significant and it meant that the nitrogen wet deposition was equally distributed in Beijing urban area. PMID:24812938

  6. Atmospheric deposition of nitrogen and sulfur in Louisiana

    NASA Astrophysics Data System (ADS)

    Zhang, H.; Guo, H.

    2015-12-01

    Wet deposition and dry deposition reduce their concentrations of sulfur and nitrogen contained air pollutants in atmosphere, but lead to increase of sulfur and nitrogen fluxes to the surface. Atmospheric deposition of sulfur and nitrogen can lead to acidification of surface water bodies (lakes, rivers, and coasts) and subsequent damage to aquatic ecosystems as well as damage to forests and vegetation. Louisiana has abundant water resources with approximately 11% of the total surface area composed of water bodies. It is important to protect water resources from excessive atmospheric deposition of sulfur and nitrogen. However, the information obtained from the observation systems for understanding the deposition of sulfur and nitrogen and the adverse effects in Louisiana is limited. This study uses a source-oriented CMAQ model to simulate emission, formation, transport, and deposition of sulfur and nitrogen species in Louisiana. WRF is used to generate the meteorological inputs and SMOKE is used to generate the emissions based on national emission inventory (NEI). The forms and quantities of sulfur and nitrogen deposition from wet and dry processes in Louisiana will be discovered. The spatial and temporal variations of sulfur and nitrogen fluxes will be quantified and contributions of major source sectors or source regions will be quantified.

  7. Atmospheric dry and wet deposition of mercury in Toronto

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaotong; Siddiqi, Zia; Song, Xinjie; Mandiwana, Khakhathi L.; Yousaf, Muhammad; Lu, Julia

    2012-04-01

    Atmospheric mercury (Hg) speciation and deposition are critical in understanding the cycling of mercury in the environment. To estimate the dry and wet deposition of mercury in an urban environment, concentrations of gaseous elemental mercury (GEM), gaseous oxidized inorganic mercury (GOIM), mercury associated with particles having size less than 2.5 μm (Hg(p) < 2.5) (December 2003-November 2004) and total particulate mercury (THg(p)) (June 2004-December 2004) in the atmosphere, as well as the concentrations of methyl mercury (MeHg) and total mercury (THg) in atmospheric precipitation samples (June 2005-January 2006 and September 2007-March 2008), were measured in downtown Toronto, Canada.The dry deposition rates of GOIM, Hg(p) < 2.5 μm and THg(p) estimated between December 2003 and December 2004 were 0.17-2.33 μg m-2 month-1, 0.04-0.32 μg m-2 month-1 and 0.17-1.11 μg m-2 month-1, respectively, while the wet deposition rates of methyl mercury and total mercury between June 2005-January 2006 and September 2007-March 2008 were 0.01-0.08 μg m-2 month-1 and 0.32-8.48 μg m-2 month-1, respectively. The total dry deposition (7.66-26.06 μg m-2 a-1, calculated as the sum of GOIM and THg(p) deposition) and the total wet deposition (= the wet deposition of total mercury = 18.60 μg m-2 a-1) contributed proportionally to the total atmospheric Hg deposition in Toronto.

  8. Atmospheric corrosion and chloride deposition on metal surfaces

    SciTech Connect

    Matthes, Steven A.; Holcomb, Gordon R.; Cramer, Stephen D.; Covino, Bernard S., Jr.; Bullard, Sophie J.

    2004-01-01

    Atmospheric corrosion and chloride deposition on metal surfaces was studied at an unpolluted coastal (marine) site, an unpolluted rural inland site, and a polluted urban site. Chloride deposition by both wet (precipitation) and dry deposition processes over a multi-year period was measured using ion chromatography analysis of incident precipitation and precipitation runoff from the surface of metal samples. Chloride deposition was measured on zinc, copper, lead, mild steel, and non-reactive blank panels, as well as two panels coated with thermal-sprayed zinc alloys. Chloride deposition measured by runoff chemistry was compared with chloride deposition measurements made by the ASTM wet candle technique. Corrosion mass loss as a function of distance from the ocean is presented for copper and mild steel in bold exposures on the west coast.

  9. An automatic collector to monitor insoluble atmospheric deposition: an application for mineral dust deposition

    NASA Astrophysics Data System (ADS)

    Laurent, B.; Losno, R.; Chevaillier, S.; Vincent, J.; Roullet, P.; Bon Nguyen, E.; Ouboulmane, N.; Triquet, S.; Fornier, M.; Raimbault, P.; Bergametti, G.

    2015-03-01

    Deposition is one of the key processes controlling the mass budget of the atmospheric mineral dust concentration. However, dust deposition remains poorly constrained in transport models simulating the atmospheric dust cycle. This is mainly due to the limited number of relevant deposition measurements. This paper aims at presenting an automatic collector (CARAGA), specially developed to sample the total (dry and wet) atmospheric deposition of insoluble dust in remote areas. The autonomy of the CARAGA can range from 25 days to almost 1 year depending on the programed sampling time step (1 day and 2 weeks sampling time steps, respectively). This collector is used to sample atmospheric deposition on Frioul Island which is located in the Gulf of Lions in the Western Mediterranean Basin over which Saharan dust can be transported and deposited. To quantify the mineral dust mass in deposition samples, a weighing and ignition protocol is applied. Two years of continuous deposition measurements performed on a weekly time step sampling on Frioul Island are presented and discussed with in-situ measurements, air mass trajectories and satellite observations of dust.

  10. Puff-Plume Atmospheric Deposition Model.

    Energy Science and Technology Software Center (ESTSC)

    1992-06-24

    Version: 00 PFPL is an interactive transport and diffusion program developed for real-time calculation of the location and concentration of toxic or radioactive materials during an accidental release. Deposition calculations are included. The potential exists at the Savannah River Plant for releases of either toxic gases or radionuclides. The automated system developed to provide real-time information on the trajectory and concentration of an accidental release consists of meteorological towers, a minicomputer, and a network ofmore » terminals called the Weather Information and Display (WIND) System. PFPL which simulates either instantaneous (puff) or continuous (plume) releases is the primary code used at Savannah River for emergency response. Data files are provided for demonstration. The software for archiving the required on-line meteorological data is not included. Subroutines used for graphic display of results and operational control of the DEC VT100 and Tektronix terminals in the terminal network are included. Anyone wishing t use these routines must make appropriate modifications to the file TERMINALS.DAT. The DAT files provided were copied during the afternoon of December 28, 1983. Test runs attempting to use these files should specify release times on or before that date. Any user wishing to obtain numerical output only form the model based on conditions in his locality must supply appropriate wind data for the program.« less

  11. An automatic collector to monitor insoluble atmospheric deposition: application for mineral dust deposition

    NASA Astrophysics Data System (ADS)

    Laurent, B.; Losno, R.; Chevaillier, S.; Vincent, J.; Roullet, P.; Bon Nguyen, E.; Ouboulmane, N.; Triquet, S.; Fornier, M.; Raimbault, P.; Bergametti, G.

    2015-07-01

    Deposition is one of the key terms of the mineral dust cycle. However, dust deposition remains poorly constrained in transport models simulating the atmospheric dust cycle. This is mainly due to the limited number of relevant deposition measurements. This paper aims to present an automatic collector (CARAGA), specially developed to sample the total (dry and wet) atmospheric deposition of insoluble dust in remote areas. The autonomy of the CARAGA can range from 25 days to almost 1 year depending on the programmed sampling frequency (from 1 day to 2 weeks respectively). This collector is used to sample atmospheric deposition of Saharan dust on the Frioul islands in the Gulf of Lions in the Western Mediterranean. To quantify the mineral dust mass in deposition samples, a weighing and ignition protocol is applied. Almost 2 years of continuous deposition measurements performed on a weekly sampling basis on Frioul Island are presented and discussed with air mass trajectories and satellite observations of dust. Insoluble mineral deposition measured on Frioul Island was 2.45 g m-2 for February to December 2011 and 3.16 g m-2 for January to October 2012. Nine major mineral deposition events, measured during periods with significant MODIS aerosol optical depths, were associated with air masses coming from the southern Mediterranean Basin and North Africa.

  12. Total atmospheric mercury deposition in forested areas in South Korea

    NASA Astrophysics Data System (ADS)

    Han, Jin-Su; Seo, Yong-Seok; Kim, Moon-Kyung; Holsen, Thomas M.; Yi, Seung-Muk

    2016-06-01

    In this study, mercury (Hg) was sampled weekly in dry and wet deposition and throughfall and monthly in litterfall, and as it was volatilized from soil from August 2008 to February 2010 to identify the factors influencing the amount of atmospheric Hg deposited to forested areas in a temperate deciduous forest in South Korea. For this location there was no significant correlation between the estimated monthly dry deposition flux (litterfall + throughfall - wet deposition) (6.7 µg m-2 yr-1) and directly measured dry deposition (9.9 µg m-2 yr-1) likely due primarily to Hg losses from the litterfall collector. Dry deposition fluxes in cold seasons (fall and winter) were lower than in warmer seasons (spring and summer). The volume-weighted mean (VWM) Hg concentrations in both precipitation and throughfall were highest in winter, likely due to increased scavenging by snow events. Since South Korea experiences abundant rainfall in summer, VWM Hg concentrations in summer were lower than in other seasons. Litterfall fluxes were highest in the late fall to early winter, when leaves were dropped from the trees (September to November). The cumulative annual Hg emission flux from soil was 6.8 µg m-2 yr-1. Based on these data, the yearly deposition fluxes of Hg calculated using two input approaches (wet deposition + dry deposition or throughfall + litterfall) were 6.8 and 3.6 µg m-2 yr-1, respectively. This is the first reported study which measured the amount of atmospheric Hg deposited to forested areas in South Korea, and thus our results provide useful information to compare against data related to Hg fate and transport in this part of the world.

  13. ANALYSIS OF ATMOSPHERE DEPOSITION SAMPLES FROM EASTON, PA

    EPA Science Inventory

    The report gives results of an analysis of samples of tenacious atmospheric deposits on exposed surfaces (e.g., automobiles and houses) in an industrial area near Easton, PA. The analysis was made at the request of the State of Pennsylvania. The Pennsylvania Department of Environ...

  14. A summary of the Lake Tahoe Atmospheric Deposition Study (LTADS)

    NASA Astrophysics Data System (ADS)

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

    2012-01-01

    The Lake Tahoe Atmospheric Deposition Study (LTADS) was conducted by the California Air Resources Board (CARB) primarily to generate refined estimates of the atmospheric deposition of nitrogen (N), phosphorous (P), and particulate matter (PM) directly to Lake Tahoe, which straddles the boundary between the states of California and Nevada in the United States of America. LTADS estimated that approximately 185, 3, and 755 metric tons respectively of N, P, and PM being directly deposited to the lake from the atmosphere. Various measurements of emissions, meteorology, and air quality were made within and west (typically upwind) of the Lake Tahoe Air Basin to better understand the pollutant sources contributing to the atmospheric deposition. The data indicate that ammonia (NH 3) contributes the bulk of the N loading. Aerosols with diameters greater than 2.5 μm contribute the bulk of the P and PM mass loadings. The emission sources of P and PM appear to be primarily local and associated with motor vehicles. However, construction, fires, and natural sources also contribute to the pollutant loadings. LTADS was part of a much larger research program to guide efforts to restore the remarkable water clarity of Lake Tahoe.

  15. TOTAL SULFUR DEPOSITION (WET+DRY) FROM THE ATMOSPHERE

    EPA Science Inventory

    Sulfur Dioxide (SO2) is emitted primarily as a by-product of coal combustion from power plants. Sulfur Dioxide reacts in the atmosphere to form other chemical such as Sulfuric Acid and Amonium Sulfate. These compounds and their secondarily formed constituents deposit to the sur...

  16. REGIONAL MODELING OF THE ATMOSPHERIC TRANSPORT AND DEPOSITION OF ATRAZINE

    EPA Science Inventory

    A version of the Community Multiscale Air Quality (CMAQ) model has been developed by the U.S. EPA that is capable of addressing the atmospheric fate, transport and deposition of some common trace toxics. An initial, 36-km rectangular grid-cell application for atrazine has been...

  17. Net atmospheric mercury deposition to Svalbard: Estimates from lacustrine sediments

    NASA Astrophysics Data System (ADS)

    Drevnick, Paul E.; Yang, Handong; Lamborg, Carl H.; Rose, Neil L.

    2012-11-01

    In this study we used lake sediments, which faithfully record Hg inputs, to derive estimates of net atmospheric Hg deposition to Svalbard, Norwegian Arctic. With the exception of one site affected by local pollution, the study lakes show twofold to fivefold increases in sedimentary Hg accumulation since 1850, likely due to long-range atmospheric transport and deposition of anthropogenic Hg. Sedimentary Hg accumulation in these lakes is a linear function of the ratio of catchment area to lake area, and we used this relationship to model net atmospheric Hg flux: preindustrial and modern estimates are 2.5 ± 3.3 μg m-2 y-1 and 7.0 ± 3.0 μg m-2 y-1, respectively. The modern estimate, by comparison with data for Hg wet deposition, indicates that atmospheric mercury depletion events (AMDEs) or other dry deposition processes contribute approximately half (range 0-70%) of the net flux. Hg from AMDEs may be moving in significant quantities into aquatic ecosystems, where it is a concern because of contamination of aquatic food webs.

  18. Atmospheric deposition of nitrogen: Potential benefits to agricultural production

    SciTech Connect

    Coveney, E.A.; Medeiros, W.H.; Moskowitz, P.D.

    1986-11-01

    Effects of indirect fertilization on agricultural lands by atmospheric deposition are examined for the four most valuable crops in the US: corn, soybean, wheat, and pasture grasses. A literature search was conducted to find suitable dose-response functions for the effects of fertilization on yield of each crop. Predicted yield changes were computed from the deposition of nitrogen to the soil in addition to nitrogen applied in accordance with current agronomic practices using these dose-response functions. Low to high nitrogen inputs from atmospheric deposition (1 to 7 kg/ha) are expected to increase the average yield of corn by 0.2 to 1.1%, soybean by 0.1 to 0.7%, wheat by 0.1 to 0.4%, and pasture grasses by 1.6 to 14%. Pasture land is predicted to receive the greatest impact because it is usually unfertilized.

  19. Atmospheric deposition of phthalate esters in a subtropical city

    NASA Astrophysics Data System (ADS)

    Zeng, Feng; Lin, Yujun; Cui, Kunyan; Wen, Jiaxin; Ma, Yongqin; Chen, Hongli; Zhu, Fang; Ma, Zhiling; Zeng, Zunxiang

    2010-02-01

    In Chinese cities, air pollution has become a serious and aggravating environmental problem undermining the sustainability of urban ecosystems and the quality of urban life. Bulk atmospheric deposition samples were collected two-weekly, from February 2007 to January 2008, at three representative areas, one suburban and two urbanized, in the subtropical city, Guangzhou, China, to assess the deposition fluxes and seasonal variations of phthalate esters (PAEs). Sixteen PAE congeners in bulk deposition samples were measured and the depositional fluxes of ∑ 16PAEs ranged from 3.41 to 190 μg m -2 day -1, and were highly affected by local anthropogenic activities. The significant relationship between PAEs and particulate depositional fluxes (correlation coefficient R2 = 0.72, P < 0.001) showed PAEs are associated primarily with particles. Temporal flux variations of PAEs were influenced by seasonal changes in meteorological parameters, and the deposition fluxes of PAEs were obviously higher in wet season than in dry season. Diisobutyl phthalate (D iBP), Di- n-butyl phthalate (D nBP), and Di(2-ethylhexyl) phthalate (DEHP) dominated the PAE pattern in bulk depositions, which is consistent with a high consumption of the plasticizer market in China. PAE profiles in bulk deposition showed similarities exhibited in both time and space, and a weak increase of high molecular weight PAE (HMW PAE) contribution in the wet season compared to those in the dry season. Average atmospheric deposition fluxes of PAEs in the present study were significantly higher than those from other studies, reflecting strong anthropogenic inputs as a consequence of rapid industrial and urban development in the region.

  20. Anthropogenic sediment resuspension mechanisms in a shallow microtidal estuary

    USGS Publications Warehouse

    Schoellhamer, D.H.

    1996-01-01

    The mechanisms that resuspend bottom sediments in Hillsborough Bay, a shallow, microtidal, subtropical estuary in West-central Florida, were determined by analysing hydrodynamic and suspended-solids concentration data collected during several instrument deployments made in 1990 and 1991. Large vessels in a dredged ship channel can generate forced solitary long waves that cause large water velocities and sediment resuspension at the study sites. An experiment was conducted with a trawler that resuspended bottom sediments, and some of the resuspended sediments remained in suspension for at least 8 h. A secondary impact of vessel-generated long waves and trawling is that sediments that are resuspended and newly deposited are more susceptible to resuspension by tidal currents than undisturbed bottom sediments. Natural sediment resuspension by wind waves and tidal current is less frequent or of smaller magnitude than anthropogenic sediment resuspension. The annual mass of sediment resuspended by vessel-generated long waves is estimated to be one order of magnitude greater than the annual mass of sediment resuspended by wind waves generated by winter storms.

  1. Role of acid rain in atmospheric deposition. Final report

    SciTech Connect

    Winchester, J.W.

    1990-12-31

    A study was conducted to assess the potential importance of atmospheric nitrate deposition for a north Florida estuary. A comparison, based on statistical analysis of fluxes of ten dissolved constituents of rain water and river water, has been carried out for the watershed of the Apalachicola River, utilizing weekly rain water chemical data from the National Acid Deposition Program (NADP) for five sites within the watershed area, monitored from 1978-84 until late 1989, and less frequent river water chemical data from the U.S. Geological Survey for one site at Chattahoochee, Florida, monitored from 1965 until late 1989. Similar statistical analysis was performed on monitoring data for the Sopchoppy and Ochlockonee Rivers of north Florida. Atmospheric deposition to the watershed appears to be sufficient to account for essentially all the dissolved nitrate and ammonium and total organic nitrogen flow in the three rivers. However, after deposition most of the nitrate may be transformed to other chemical forms during the flow of the rivers toward their estuaries. In an additional statistical analysis of rain water monitoring data from the eight state southeastern USA region, it was found that both meteorological conditions and transport from pollution sources appear to control deposition fluxes of nitrate and sulfate acid air pollutants.

  2. Atmospheric deposition of phosphorus to land and freshwater.

    PubMed

    Tipping, E; Benham, S; Boyle, J F; Crow, P; Davies, J; Fischer, U; Guyatt, H; Helliwell, R; Jackson-Blake, L; Lawlor, A J; Monteith, D T; Rowe, E C; Toberman, H

    2014-07-01

    We compiled published and newly-obtained data on the directly-measured atmospheric deposition of total phosphorus (TP), filtered total phosphorus (FTP), and inorganic phosphorus (PO4-P) to open land, lakes, and marine coasts. The resulting global data base includes data for c. 250 sites, covering the period 1954 to 2012. Most (82%) of the measurement locations are in Europe and North America, with 44 in Africa, Asia, Oceania, and South-Central America. The deposition rates are log-normally distributed, and for the whole data set the geometric mean deposition rates are 0.027, 0.019 and 0.14 g m(-2) a(-1) for TP, FTP and PO4-P respectively. At smaller scales there is little systematic spatial variation, except for high deposition rates at some sites in Germany, likely due to local agricultural sources. In cases for which PO4-P was determined as well as one of the other forms of P, strong parallels between logarithmic values were found. Based on the directly-measured deposition rates to land, and published estimates of P deposition to the oceans, we estimate a total annual transfer of P to and from the atmosphere of 3.7 Tg. However, much of the phosphorus in larger particles (principally primary biological aerosol particles) is probably redeposited near to its origin, so that long-range transport, important for tropical forests, large areas of peatland and the oceans, mainly involves fine dust from deserts and soils, as described by the simulations of Mahowald et al. (Global Biogeochemical Cycles 22, GB4026, 2008). We suggest that local release to the atmosphere and subsequent deposition bring about a pseudo-diffusive redistribution of P in the landscape, with P-poor ecosystems, for example ombrotrophic peatlands and oligotrophic lakes, gaining at the expense of P-rich ones. Simple calculations suggest that atmospheric transport could bring about significant local redistribution of P among terrestrial ecosystems. Although most atmospherically transported P is natural

  3. Thin film deposition by means of atmospheric pressure microplasma jet

    NASA Astrophysics Data System (ADS)

    Benedikt, J.; Raballand, V.; Yanguas-Gil, A.; Focke, K.; von Keudell, A.

    2007-12-01

    An RF microplasma jet working at atmospheric pressure has been developed for thin film deposition application. It consists of a capillary coaxially inserted in the ceramic tube. The capillary is excited by an RF frequency of 13.56 MHz at rms voltages of around 200-250 V. The plasma is generated in a plasma forming gas (helium or argon) in the annular space between the capillary and the ceramic tube. By adjusting the flows, the flow pattern prevents the deposition inside the source and mixing of the reactive species with the ambient air in the discharge and deposition region, so that no traces of air are found even when the microplasma is operated in an air atmosphere. All these properties make our microplasma design of great interest for applications such as thin film growth or surface treatment. The discharge operates probably in a γ-mode as indicated by high electron densities of around 8 × 1020 m-3 measured using optical emission spectroscopy. The gas temperature stays below 400 K and is close to room temperature in the deposition region in the case of argon plasma. Deposition of hydrogenated amorphous carbon films and silicon oxide films has been tested using Ar/C2H2 and Ar/hexamethyldisiloxane/O2 mixtures, respectively. In the latter case, good control of the film properties by adjusting the source parameters has been achieved with the possibility of depositing carbon free SiOx films even without the addition of oxygen. Preliminary results regarding permeation barrier properties of deposited films are also given.

  4. Effect of atmospheric electricity on dry deposition of airborne particles from atmosphere

    NASA Astrophysics Data System (ADS)

    Tammet, H.; Kimmel, V.; Israelsson, S.

    The electric mechanism of dry deposition is well known in the case of unattached radon daughter clusters that are unipolar charged and of high mobility. The problematic role of the electric forces in deposition of aerosol particles is theoretically examined by comparing the fluxes of particles carried by different deposition mechanisms in a model situation. The electric mechanism of deposition appears essential for particles of diameter 10-200 nm in conditions of low wind speed. The electric flux of fine particles can be dominant on the tips of leaves and needles even in a moderate atmospheric electric field of a few hundred V m -1 measured over the plane ground surface. The electric deposition is enhanced under thunderclouds and high voltage power lines. Strong wind suppresses the relative role of the electric deposition when compared with aerodynamic deposition. When compared with diffusion deposition the electric deposition appears less uniform: the precipitation particulate matter on the tips of leaves and especially on needles of top branches of conifer trees is much more intensive than on the ground surface and electrically shielded surfaces of plants. The knowledge of deposition geometry could improve our understanding of air pollution damage to plants.

  5. Oceanic Emissions and Atmospheric Depositions of Volatile Organic Compounds

    NASA Astrophysics Data System (ADS)

    Yang, M.; Blomquist, B.; Beale, R.; Nightingale, P. D.; Liss, P. S.

    2015-12-01

    Atmospheric volatile organic compounds (VOCs) affect the tropospheric oxidative capacity due to their ubiquitous abundance and relatively high reactivity towards the hydroxyal radical. Over the ocean and away from terrestrial emission sources, oxygenated volatile organic compounds (OVOCs) make up a large fraction of VOCs as airmasses age and become more oxidized. In addition to being produced or destroyed in the marine atmosphere, OVOCs can also be emitted from or deposited to the surface ocean. Here we first present direct air-sea flux measurements of three of the most abundant OVOCs - methanol, acetone, and acetaldehyde, by the eddy covariance technique from two cruises in the Atlantic: the Atlantic Meridional Transect in 2012 and the High Wind Gas Exchange Study in 2013. The OVOC mixing ratios were quantified by a high resolution proton-reaction-transfer mass spectrometer with isotopically labeled standards and their air-sea (net) fluxes were derived from the eddy covariance technique. Net methanol flux was consistently from the atmosphere to the surface ocean, while acetone varied from supersaturation (emission) in the subtropics to undersaturation (deposition) in the higher latitudes of the North Atlantic. The net air-sea flux of acetaldehyde is near zero through out the Atlantic despite the apparent supersaturation of this compound in the surface ocean. Knowing the dissolved concentrations and in situ production rates of these compounds in seawater, we then estimate their bulk atmospheric depositions and oceanic emissions. Lastly, we summarize the state of knowledge on the air-sea transport of a number of organic gasses, and postulate the magnitude and environmental impact of total organic carbon transfer between the ocean and the atmosphere.

  6. Protocol for estimating historic atmospheric mercury deposition. Final report

    SciTech Connect

    1996-08-01

    The varied chemical phases and forms of mercury promote its transport and cycling in the environment between water, soil, and air. Many sources--both natural and anthropogenic--contribute to the atmospheric mercury cycle, while several factors modify its deposition and subsequent transformation, distribution, and bioaccumulation. This report introduces a protocol for quantifying spatial and temporal mercury deposition and improving site-to-site comparability of mercury accumulation measurements in natural archives. The report describes the selection of appropriate coring sites to measure mercury accumulation, field methods for lake sediment coring, analysis of sediments, and interpretation of the results from stratigraphic mercury analyses. The new EPRI protocol is expected not only to spur research methods but also to facilitate the global picture of historic mercury deposition needed by policymakers in public organizations, industry, and government.

  7. Deposition of carbon nanostructures on metal substrates at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Dimitrov, Zh; Nikovski, M.; Kiss'ovski, Zh

    2016-03-01

    The microwave-plasma-enhanced CVD of carbon nanostructures at atmospheric pressure allows shorter deposition times and reduces the complexity of the experimental set-up. In our study, the substrate temperature was varied in a wide range (300 – 700 C) using microwave plasma heating, as well as an additional heater. The distance between the substrate and the plasma flame was also varied in order to establish the conditions for an efficient deposition process, the latter being carried out at specific argon/hydrogen/methane gas mixtures. Optical measurements of the plasma flame spectrum were conducted to obtain the gas temperature and the plasma density and to analyze the existence of reactive species. The carbon nanostructures deposited on the metal samples were investigated by SEM. The relation between the morphology and the gas-discharge conditions is discussed.

  8. Impact of increased anthropogenic atmospheric nitrogen deposition on ocean biogeochemistry

    NASA Astrophysics Data System (ADS)

    Yang, Simon; Gruber, Nicolas

    2015-04-01

    In the last century, the strong increase in anthropogenic emissions and agricultural activities brought about a tripling in atmospheric nitrogen deposition (AND) rates to oceans. There is growing evidence for a strong fingerprint of increased AND on aquatic systems. Increases in excess N over P (N*) have been attributed to the growing anthropogenically sourced N-deposition in the North western Pacific (Kim et al. 2011) and the North Pacific (Kim et al. 2014). In this study, we use the ocean component of the global earth system model CESM and forced it with transient atmospheric nitrogen deposition from 1850 to 2000 (Lamarque et al. 2013) to study the impact of increased N-deposition on ocean biogeochemistry. We simulate detectable signals in N* in the northern hemisphere as well as a complex pattern of increases and decreases in ocean productivity, with the former causing an expansion of oxygen minimum zones and an increase in water column denitrification. The increase in AND also reduces the ecological niches for N2-fixers, causing a substantial decrease in global ocean N-fixation. Despite this increase in N-loss by denitrification and decrease in N-gain by N-fixation, the increase in AND has put the global marine N-budget severely out of balance ( 10 TgN.yr-1). Finally, we extend our simulation to 2100 using the RCP 8.5 emission scenario to find that these changes will probably grow in the future.

  9. Atmospheric sulfur deposition and streamwater quality in Finland

    NASA Astrophysics Data System (ADS)

    Lahermo, P. W.; Tarvainen, T.; Tuovinen, J.-P.

    1994-10-01

    The correlation between sulfate concentrations in Finnish headwater streams and atmospheric sulfate deposition has been studied by using data from the streamwater chemistry in August September 1990 and computed S deposition from the anthropogenic emissions. The sulfate concentrations and acidity in water are interpolated and smoothed into a deposition model grid. These data are compared with geological and pedogeochemical (glacial till) background information. The areas where the streamwater SO4 concentrations are mainly controlled by either anthropogenic S deposition or sulfur in till is estimated by applying the fuzzy Gustafsson-Kessel algorithm, which provides a soft clustering suitable for overlapping control factors. Residual areas can be well explained by the SO4-rich Littorina clay deposits. The higher overall background SO4 concentrations in streams in south Finland compared with central and northern Finland are an indisputable consequence of the heavier S deposition load in the south. However, anthropogenic sulfur deposition has a clear correlation with the sulfates in streamwaters only in northeastern Lapland impacted by the large industrial emissions in the Kola Peninsula. The secondary sulfide and sulfate minerals of marine Littorina sediments are dominating sources in the broad coastal belts, as are the primary sulfide minerals locally in the Pori-Vammala area, at the eastern end of the main sulfide ore belt between Lake Ladoga and the Gulf of Bothnia, in the Outokumpu area, and in the Peräpohja and central Lapland schist belts. Consequently, in addition to the anthropogenic deposition, there are natural sources of sulfur which cause acidity of streamwaters.

  10. Modeling Planetary Atmospheric Energy Deposition By Energetic Ions

    NASA Astrophysics Data System (ADS)

    Parkinson, Christopher; Bougher, Stephen; Gronoff, Guillaume; Barthelemy, Mathieu

    2016-07-01

    The structure, dynamics, chemistry, and evolution of planetary upper atmospheres are in large part determined by the available sources of energy. In addition to the solar EUV flux, the solar wind and solar energetic particle (SEP) events are also important sources. Both of these particle populations can significantly affect an atmosphere, causing atmospheric loss and driving chemical reactions. Attention has been paid to these sources from the standpoint of the radiation environment for humans and electronics, but little work has been done to evaluate their impact on planetary atmospheres. At unmagnetized planets or those with crustal field anomalies, in particular, the solar wind and SEPs of all energies have direct access to the atmosphere and so provide a more substantial energy source than at planets having protective global magnetic fields. Additionally, solar wind and energetic particle fluxes should be more significant for planets orbiting more active stars, such as is the case in the early history of the solar system for paleo-Venus and Mars. Therefore quantification of the atmospheric energy input from the solar wind and SEP events is an important component of our understanding of the processes that control their state and evolution. We have applied a full Lorentz motion particle transport model to study the effects of particle precipitation in the upper atmospheres of Mars and Venus. Such modeling has been previously done for Earth and Mars using a guiding center precipitation model. Currently, this code is only valid for particles with small gyroradii in strong uniform magnetic fields. There is a clear necessity for a Lorentz formulation, hence, a systematic study of the ionization, excitation, and energy deposition has been conducted, including a comparison of the influence relative to other energy sources (namely EUV photons). The result is a robust examination of the influence of energetic ion transport on the Venus and Mars upper atmosphere which

  11. Modeling Atmospheric Energy Deposition (by energetic ions): New Results

    NASA Astrophysics Data System (ADS)

    Parkinson, C.; Brain, D. A.; Lillis, R. J.; Liemohn, M. W.; Bougher, S. W.

    2012-12-01

    The structure, dynamics, chemistry, and evolution of planetary upper atmospheres are in large part determined by the available sources of energy. In addition to the solar EUV flux, the solar wind and solar energetic particle (SEP) events are also important sources. Both of these particle populations can significantly affect an atmosphere, causing atmospheric loss and driving chemical reactions. Attention has been paid to these sources from the standpoint of the radiation environment for humans and electronics, but little work has been done to evaluate their impact on planetary atmospheres. At unmagnetized planets or those with crustal field anomalies, in particular, the solar wind and SEPs of all energies have direct access to the atmosphere and so provide a more substantial energy source than at planets having protective global magnetic fields. Additionally, solar wind and energetic particle fluxes should be more significant for planets orbiting more active stars, such as is the case in the early history of the solar system for paleo-Venus and Mars. Therefore quantification of the atmospheric energy input from the solar wind and SEP events is an important component of our understanding of the processes that control their state and evolution. Such modeling has been previously done for Earth, Mars and Jupiter using a guiding center precipitation model with extensive collisional physics. Currently, this code is only valid for particles with small gyroradii in strong uniform magnetic fields. There is a clear necessity for a Lorentz formulation that can perform calculations for cases where there is only a weak or nonexistent magnetic field that includes detailed physical interaction with the atmosphere (i.e. collisional physics). We show initial efforts to apply a full Lorentz motion particle transport model to study the effects of particle precipitation in the upper atmospheres of Venus, Mars, and Titan. A systematic study of the ionization, excitation, and energy

  12. Mechanisms controlling soil carbon sequestration under atmospheric nitrogen deposition

    SciTech Connect

    R.L. Sinsabaugh; D.R. Zak; D.L. Moorhead

    2008-02-19

    Increased atmospheric nitrogen (N) deposition can alter the processing and storage of organic carbon in soils. In 2000, we began studying the effects of simulated atmospheric N deposition on soil carbon dynamics in three types of northern temperate forest that occur across a wide geographic range in the Upper Great Lakes region. These ecosystems range from 100% oak in the overstory (black oak-white oak ecosystem; BOWO) to 0% overstory oak (sugar maple-basswood; SMBW) and include the sugar maple-red oak ecosystem (SMRO) that has intermediate oak abundance. The leaf litter biochemistry of these ecosystems range from highly lignified litter (BOWO) to litter of low lignin content (SMBW). We selected three replicate stands of each ecosystem type and established three plots in each stand. Each plot was randomly assigned one of three levels of N deposition (0, 30 & 80 kg N ha-1 y-1) imposed by adding NaNO3 in six equal increments applied over the growing season. Through experiments ranging from the molecular to the ecosystem scales, we produced a conceptual framework that describes the biogeochemistry of soil carbon storage in N-saturated ecosystems as the product of interactions between the composition of plant litter, the composition of the soil microbial community and the expression of extracellular enzyme activities. A key finding is that atmospheric N deposition can increase or decrease the soil C storage by modifying the expression of extracellular enzymes by soil microbial communities. The critical interactions within this conceptual framework have been incorporated into a new class of simulations called guild decomposition models.

  13. Ammonia in the atmosphere: a review on emission sources, atmospheric chemistry and deposition on terrestrial bodies.

    PubMed

    Behera, Sailesh N; Sharma, Mukesh; Aneja, Viney P; Balasubramanian, Rajasekhar

    2013-11-01

    Gaseous ammonia (NH3) is the most abundant alkaline gas in the atmosphere. In addition, it is a major component of total reactive nitrogen. The largest source of NH3 emissions is agriculture, including animal husbandry and NH3-based fertilizer applications. Other sources of NH3 include industrial processes, vehicular emissions and volatilization from soils and oceans. Recent studies have indicated that NH3 emissions have been increasing over the last few decades on a global scale. This is a concern because NH3 plays a significant role in the formation of atmospheric particulate matter, visibility degradation and atmospheric deposition of nitrogen to sensitive ecosystems. Thus, the increase in NH3 emissions negatively influences environmental and public health as well as climate change. For these reasons, it is important to have a clear understanding of the sources, deposition and atmospheric behaviour of NH3. Over the last two decades, a number of research papers have addressed pertinent issues related to NH3 emissions into the atmosphere at global, regional and local scales. This review article integrates the knowledge available on atmospheric NH3 from the literature in a systematic manner, describes the environmental implications of unabated NH3 emissions and provides a scientific basis for developing effective control strategies for NH3. PMID:23982822

  14. Atmospheric interactions during global deposition of Chicxulub impact ejecta

    NASA Astrophysics Data System (ADS)

    Goldin, Tamara Joan

    Atmospheric interactions affected both the mechanics of impact ejecta deposition and the environmental effects from the catastrophic Chicxulub impact at the Cretaceous-Paleogene (K-Pg) boundary. Hypervelocity reentry and subsequent sedimentation of Chicxulub impact spherules through the Earth's atmosphere was modeled using the KFIX-LPL two-phase flow code, which includes thermal radiation and operates at the necessary range of flow regimes and velocities. Spherules were injected into a model mesh approximating a two-dimensional slice of atmosphere at rates based on ballistic models of impact plume expansion. The spherules decelerate due to drag, compressing the upper atmosphere and reaching terminal velocity at ˜70 km in altitude. A band of spherules accumulates at this altitude, below which is compressed cool air and above which is hot (>3000 K) relatively-empty atmosphere. Eventually the spherule-laden air becomes unstable and density currents form, transporting the spherules through the lower atmosphere collectively as plumes rather than individually at terminal velocity. This has implications for the depositional style and sedimentation rate of the global K-Pg boundary layer. Vertical density current formation in both incompressible (water) and compressible (air) fluids is evaluated numerically via KFIX-LPL simulations and analytically using new instability criteria. Models of density current formation due to particulate loading of water are compared to tephra fall experiments in order to validate the model instabilities. The impact spherules themselves obtain peak temperatures of 1300-1600 K and efficiently radiate that heat as thermal radiation. However, the downward thermal radiation emitted from decelerating spherules is increasingly blocked by previously-entered spherules settling lower in the atmosphere. This self-shielding effect strengthens with time as the settling spherule cloud thickens and becomes increasingly opaque, limiting both the magnitude

  15. The effects of uncertainty on the analysis of atmospheric deposition

    SciTech Connect

    Bloyd, C.N. ); Small, M.J.; Henrion, M.; Rubin, E.S. )

    1988-01-01

    Research efforts on the problem of acid ran are directed at improving current scientific understanding in critical areas, including sources of precursor emissions, the transport and transformation of pollutants in the atmosphere, the deposition of acidic species, and the chemical and biological effects of acid deposition on aquatic systems, materials, forests, crops and human health. The general goal of these research efforts is to characterize the current situation and to develop analytical models which can be used to predict the response of various systems to changes in critical parameters. This paper describes a framework which enables one to characterize uncertainty at each major stage of the modeling process. Following a general presentation of the modeling framework, a description is given of the methods chosen to characterize uncertainty for each major step. Analysis is then performed to illustrate the effects of uncertainty on future lake acidification in the Adirondacks Park area of upstate New York.

  16. Response of global soil consumption of atmospheric methane to changes in atmospheric climate and nitrogen deposition

    USGS Publications Warehouse

    Zhuang, Qianlai; Chen, Min; Xu, Kai; Tang, Jinyun; Saikawa, Eri; Lu, Yanyu; Melillo, Jerry M.; Prinn, Ronald G.; McGuire, A. David

    2013-01-01

    Soil consumption of atmospheric methane plays an important secondary role in regulating the atmospheric CH4 budget, next to the dominant loss mechanism involving reaction with the hydroxyl radical (OH). Here we used a process-based biogeochemistry model to quantify soil consumption during the 20th and 21st centuries. We estimated that global soils consumed 32–36 Tg CH4 yr−1 during the 1990s. Natural ecosystems accounted for 84% of the total consumption, and agricultural ecosystems only consumed 5 Tg CH4 yr−1 in our estimations. During the twentieth century, the consumption rates increased at 0.03–0.20 Tg CH4 yr−2 with seasonal amplitudes increasing from 1.44 to 3.13 Tg CH4 month−1. Deserts, shrublands, and xeric woodlands were the largest sinks. Atmospheric CH4 concentrations and soil moisture exerted significant effects on the soil consumption while nitrogen deposition had a moderate effect. During the 21st century, the consumption is predicted to increase at 0.05-1.0 Tg CH4 yr−2, and total consumption will reach 45–140 Tg CH4 yr−1 at the end of the 2090s, varying under different future climate scenarios. Dry areas will persist as sinks, boreal ecosystems will become stronger sinks, mainly due to increasing soil temperatures. Nitrogen deposition will modestly reduce the future sink strength at the global scale. When we incorporated the estimated global soil consumption into our chemical transport model simulations, we found that nitrogen deposition suppressed the total methane sink by 26 Tg during the period 1998–2004, resulting in 6.6 ppb higher atmospheric CH4 mixing ratios compared to without considering nitrogen deposition effects. On average, a cumulative increase of every 1 Tg soil CH4 consumption decreased atmospheric CH4 mixing ratios by 0.26 ppb during the period 1998–2004.

  17. Reconstruction of atmospheric concentrations and deposition of uranium and decay products released from the former uranium mill at Uravan, Colorado.

    PubMed

    Rood, Arthur S; Voillequé, Paul G; Rope, Susan K; Grogan, Helen A; Till, John E

    2008-08-01

    Radionuclide concentrations in air from uranium milling emissions were estimated for the town of Uravan, Colorado, USA and the surrounding area for a 49-yr period of mill operations beginning in 1936 and ending in 1984. Milling processes with the potential to emit radionuclides to the air included crushing and grinding of ores; conveyance of ore; ore roasting, drying, and packaging of the product (U(3)O(8)); and fugitive dust releases from ore piles, tailings' piles, and roads. The town of Uravan is located in a narrow canyon formed by the San Miguel River in western Colorado. Atmospheric transport modeling required a complex terrain model. Because historical meteorological data necessary for a complex terrain model were lacking, meteorological instruments were installed, and relevant data were collected for 1 yr. Monthly average dispersion and deposition factors were calculated using the complex terrain model, CALPUFF. Radionuclide concentrations in air and deposition on ground were calculated by multiplying the estimated source-specific release rate by the dispersion or deposition factor. Time-dependent resuspension was also included in the model. Predicted concentrations in air and soil were compared to measurements from continuous air samplers from 1979 to 1986 and to soil profile sampling performed in 2006. The geometric mean predicted-to-observed ratio for annual average air concentrations was 1.25 with a geometric standard deviation of 1.8. Predicted-to-observed ratios for uranium concentrations in undisturbed soil ranged from 0.67 to 1.22. Average air concentrations from 1936 to 1984 in housing blocks ranged from about 2.5 to 6 mBq m(-3) for (238)U and 1.5 to 3.5 mBq m(-3) for (230)Th, (226)Ra, and (210)Pb. PMID:18448213

  18. Electron deposition in water vapor, with atmospheric applications.

    NASA Technical Reports Server (NTRS)

    Olivero, J. J.; Stagat, R. W.; Green, A. E. S.

    1972-01-01

    Examination of the consequences of electron impact on water vapor in terms of the microscopic details of excitation, dissociation, ionization, and combinations of these processes. Basic electron-impact cross-section data are assembled in many forms and are incorporated into semianalytic functions suitable for analysis with digital computers. Energy deposition in water vapor is discussed, and the energy loss function is presented, along with the 'electron volts per ion pair' and the efficiencies of energy loss in various processes. Several applications of electron and water-vapor interactions in the atmospheric sciences are considered, in particular, H2O comets, aurora and airglow, and lightning.

  19. Stable isotopes in alpine precipitation as tracers of atmospheric deposition

    NASA Astrophysics Data System (ADS)

    Wasiuta, V. L.; Lafreniere, M. J.; Kyser, T. K.; Norman, A. L.; Mayer, B.; Wieser, M.

    2010-12-01

    Alpine ecosystems, which are generally nutrient poor and exist under extreme climatic conditions, are particularly sensitive to environmental and climatic stressors. Studies in the USA Rocky Mountains and European Alps have shown that alpine terrestrial and aquatic ecosystems are particularly sensitive to enhanced deposition of reactive nitrogen and can show ecologically destructive responses at relatively low levels of nitrogen deposition. However, there is no base line for atmospheric deposition of natural and anthropogenic contaminants in the Canadian alpine. Preliminary results of isotopic and chemical analyses of precipitation from an elevational transect on a glaciated alpine site in the Canadian Rockies are presented. Precipitation accumulating from early autumn through to spring (2008/2009 and 2009/2010) was sampled by means of seasonal snow cover on alpine glaciers. Summer precipitation was sampled through July and August 2010 using bulk collectors installed at the sites of winter sampling. The isotope ratios of dissolved sulphate (δ34S, δ18O), nitrogen (δ15N, δ18O), as well as precipitation (δ2H, δ18O) are utilized in addition to major ion concentrations and trace metal concentrations. Results from 2008/2009 snowpack samples indicate a strong seasonal trend in sulphate (SO42-) and nitrogen (NO3-) deposition which is consistent across the altitudinal transect. Snow horizons representing early autumn and spring precipitation show higher SO42- and NO3- concentrations in contrast to lower concentrations in winter horizons. The aforementioned suite of isotopic and chemical analyses are used to investigate the variability in dominant geographic source regions for atmospheric SO42- and NO3- (local, regional, or long range transported contaminants), as well as to identify contributions from the major biogeochemical source types (e.g. hydrocarbon combustion, lithogenic dust, agricultural emissions).

  20. Energy deposition of corpuscular radiation in the middle atmosphere

    NASA Technical Reports Server (NTRS)

    Kudela, K.

    1989-01-01

    Main components of corpuscular radiation contributing to energy deposition (ED in eV/cu cm/s) in the atmosphere (10 to 100 km) are cosmic ray nuclei (CR - galactic and solar) and high energy electrons (HEE), mainly of magnetospheric origin. Galactic CR depending on solar cycle phase and latitude are dominant source of ED by corpuscular radiation below 50 to 60 km. Below 20 km secondaries must be assumed. More accurate treatment need assuming of individual HE solar flare particles, cut off rigidities in geomagnetic field and their changes during magnetospheric disturbances. Electrons E sub e greater than 30 keV of magnetospheric origin penetrating to atmosphere contribute to production rate below 100 km especially on night side. High temporal variability, local time dependence and complicated energy spectra lead to complicated structure of electron ED rate. Electrons of MeV energy found at geostationary orbit, pronouncing relation to solar and geomagnetic activity, cause maximum ED at 40 to 60 km. Monitoring the global distribution of ED by corpuscular radiation in middle atmosphere need continuing low altitude satellite measurements of both HEE and x ray BS from atmosphere as well as measurements of energy spectra and charge composition of HE solar flare particles.

  1. Atmospheric Plasma Deposition of Diamond-like Carbon Coatings

    SciTech Connect

    Ladwig, Angela

    2008-01-23

    material that may be treated. The deposition of DLC at atmospheric pressure has been demonstrated by several researchers. Izake, et al [53] and Novikov and Dymont [54] have demonstrated an electrochemical process that is carried out with organic compounds such as methanol and acetylene dissolved in ammonia. This process requires that the substrates be immersed in the liquid [53-54]. The atmospheric pressure deposition of DLC was also demonstrated by Kulik, et al. utilizing a plasma torch. However, this process requires operating temperatures in excess of 800 oC [55]. In this report, we investigate the deposition of diamond-like carbon films using a low temperature, atmospheric pressure plasma-enhanced chemical vapor deposition (PECVD) process. The films were characterized by solid-state carbon-13 nuclear magnetic resonance (13C NMR) and found to have a ratio of sp2 to sp3 carbon of 43 to 57%. The films were also tested for adhesion, coefficient of friction, and dielectric strength.

  2. Modeling and Mapping of Atmospheric Mercury Deposition in Adirondack Park, New York

    PubMed Central

    Yu, Xue; Driscoll, Charles T.; Huang, Jiaoyan; Holsen, Thomas M.; Blackwell, Bradley D.

    2013-01-01

    The Adirondacks of New York State, USA is a region that is sensitive to atmospheric mercury (Hg) deposition. In this study, we estimated atmospheric Hg deposition to the Adirondacks using a new scheme that combined numerical modeling and limited experimental data. The majority of the land cover in the Adirondacks is forested with 47% of the total area deciduous, 20% coniferous and 10% mixed. We used litterfall plus throughfall deposition as the total atmospheric Hg deposition to coniferous and deciduous forests during the leaf-on period, and wet Hg deposition plus modeled atmospheric dry Hg deposition as the total Hg deposition to the deciduous forest during the leaf-off period and for the non-forested areas year-around. To estimate atmospheric dry Hg deposition we used the Big Leaf model. The average atmospheric Hg deposition to the Adirondacks was estimated as 17.4 g m yr with a range of −3.7–46.0 g m yr. Atmospheric Hg dry deposition (370 kg yr) was found to be more important than wet deposition (210 kg yr) to the entire Adirondacks (2.4 million ha). The spatial pattern showed a large variation in atmospheric Hg deposition with scattered areas in the eastern Adirondacks having total Hg deposition greater than 30 μg m−2 yr−1, while the southwestern and the northern areas received Hg deposition ranging from 25–30 μg m−2 yr−1. PMID:23536871

  3. Pacific Northwest Laboratory annual report for 1985 to the DOE Office of Energy Research. Part 3. Atmospheric sciences

    SciTech Connect

    Elderkin, C.E.

    1986-02-01

    The goals of atmospheric research at Pacific Northwest Laboratory (PNL) are to describe and predict the nature and fate of atmospheric contaminants and to develop an understanding of the atmospheric processes contributing to their distribution on local, regional, and continental scales. In 1985, this research has examined the transport and diffusion of atmospheric contaminants in areas of complex terrain, summarized the field studies and analyses of dry deposition and resuspension conducted in past years, and begun participation in a large, multilaboratory program to assess the precipitation scavenging processes important to the transformation and wet deposition of chemicals composing ''acid rain.'' The description of atmospheric research at PNL is organized in terms of the following study areas: Atmospheric Studies in Complex Terrain; Dispersion, Deposition, and Resuspension of Atmospheric Contaminants; and Processing of Emissions by Clouds and Precipitation (PRECP).

  4. Energetic particle energy deposition in Titan's upper atmosphere

    NASA Astrophysics Data System (ADS)

    Westlake, J. H.; Smith, H. T.; Mitchell, D. G.; Paranicas, C. P.; Rymer, A. M.; Bell, J. M.; Waite, J. H., Jr.; Mandt, K. E.

    2012-04-01

    Titan’s upper atmosphere has been observed to be variable on a pass-by-pass basis. During the nominal mission where the Cassini Ion and Neutral Mass Spectrometer (INMS) only sampled the northern hemisphere this variability was initially believed to be tied to solar drivers manifest in latitudinal variations in the thermal structure of the upper atmosphere. However, when Cassini delved into the southern hemisphere the latitudinal dependence was not present in the data. Recently, Westlake et al. (2011) showed that the pass-by-pass variability is correlated with the deviations in the plasma environment as identified by Rymer et al. (2009) and Simon et al. (2010). Furthermore, the studies of Westlake et al. (2011) and Bell et al. (2011) showed that Titan’s upper atmosphere responds to changes in the ambient magnetospheric plasma on timescales of roughly one Titan day (16 Earth days). We report on recent studies of energy deposition in Titan’s upper atmosphere. Previous studies by Smith et al. (2009), Cravens et al. (2008), Tseng et al. (2008), and Shah et al. (2009) reported on energetic proton and oxygen ion precipitation. Back of the envelope calculations by Sittler et al. (2009) showed that magnetospheric energy inputs are expected to be of the order of or greater than the solar processes. We report on further analysis of the plasma environment around Titan during the flybys that the INMS has good data. We utilize data from the Magnetospheric Imaging Instrument to determine how the magnetospheric particle population varies from pass to pass and how this influences the net magnetospheric energy input prior to the flyby. We also report on enhanced energetic neutral atom emissions during select highly energetic passes. References: Bell, J., et al.: “Simulating the time-dependent response of Titan's upper atmosphere to periods of magnetospheric forcing”. Geophys. Res. Lett., Vol. 38, L06202, 2011. Rymer, A. M., et al.: “Discrete classification and electron

  5. Multi-elements atmospheric deposition study in Albania.

    PubMed

    Qarri, Flora; Lazo, Pranvera; Stafilov, Trajce; Frontasyeva, Marina; Harmens, Harry; Bekteshi, Lirim; Baceva, Katerina; Goryainova, Zoya

    2014-02-01

    For the first time, the moss biomonitoring technique and inductively coupled plasma-atomic emission spectrometric (ICP-AES) analytical technique were applied to study multi-element atmospheric deposition in Albania. Moss samples (Hypnum cupressiforme) were collected during the summer of 2011 and September-October 2010 from 62 sites, evenly distributed over the country. Sampling was performed in accordance with the LRTAP Convention-ICP Vegetation protocol and sampling strategy of the European Programme on Biomonitoring of Heavy Metal Atmospheric Deposition. ICP-AES analysis made it possible to determine concentrations of 19 elements including key toxic metals such as Pb, Cd, As, and Cu. Cluster and factor analysis with varimax rotation was applied to distinguish elements mainly of anthropogenic origin from those predominantly originating from natural sources. Geographical distribution maps of the elements over the sampled territory were constructed using GIS technology. The median values of the elements in moss samples of Albania were high for Al, Cr, Ni, Fe, and V and low for Cd, Cu, and Zn compared to other European countries, but generally were of a similar level as some of the neighboring countries such as Bulgaria, Croatia, Kosovo, Macedonia, and Romania. This study was conducted in the framework of ICP Vegetation in order to provide a reliable assessment of air quality throughout Albania and to produce information needed for better identification of contamination sources and improving the potential for assessing environmental and health risks in Albania, associated with toxic metals. PMID:24081920

  6. Atmospheric lead deposition to Okefenokee Swamp, Georgia, USA

    USGS Publications Warehouse

    Jackson, B.P.; Winger, P.V.; Lasier, P.J.

    2004-01-01

    'Capsule:' Coal combustion emissions appear to be a major source of Pb in the Okefenokee wetland. Contamination of the environment from atmospheric deposition during the twentieth century is pervasive even in areas ostensibly considered pristine or remote from point sources. In this study, Pb concentrations in a Pb-210-dated peat core collected from the Okefenokee Swamp, GA were used to assess historical contaminant input via atmospheric deposition. Lead isotope ratios were determined by dynamic reaction cell ICP-MS (DRC-ICP-MS). Increases in Pb concentration occurred in the late nineteenth century and a marked rise in Pb concentrations pre-dated the widespread use of leaded gasoline within the US. The Pb-206/Pb-207 ratios of 1.19 during this period were consistent with coal combustion emissions. A later increase in Pb concentration, concurrent with a trend toward more radiogenic Pb-206/Pb-207 ratios in gasoline is consistent with an increased input of Pb from leaded gasoline emissions. However, it appears that coal combustion emissions remain a major source of Pb to the Okefenokee.

  7. Atmospheric deposition and isotope biogeochemistry of zinc in ombrotrophic peat

    NASA Astrophysics Data System (ADS)

    Weiss, Dominik J.; Rausch, Nicole; Mason, Thomas F. D.; Coles, Barry J.; Wilkinson, Jamie J.; Ukonmaanaho, Liisa; Arnold, Tim; Nieminen, Tiina M.

    2007-07-01

    Zinc isotope ratios were measured in the top sections of dated ombrotrophic peat cores in Finland to investigate their potential as proxies for atmospheric sources and to constrain post depositional processes affecting the geochemical record. The peat deposits were located in Hietajärvi, a background site well away from any point pollution source and representing 'background' conditions, in Outokumpu, next to a mining site, and in Harjavalta, next to a smelter. Measured total concentrations, calculated excess concentrations and mass balance considerations suggest that zinc is subjected to important biogeochemical cycling within the peat. Significant isotopic variability was found in all three peat bogs, with heavier zinc in the deeper and lighter zinc in the upper sections. Isotope ratios and concentrations correlated in the two peats located next to dominant point sources, i.e. the smelting and mining site, suggesting that zinc isotopes trace pollution sources. Concentration and isotope peaks were offset from the period of mining and smelting activity, supporting migration of zinc down the profile. The δ 66Zn JMC (where δ 66Zn = [( 66Zn/ 64Zn) sample/( 66Zn/ 64Zn) JMC-standard - 1] × 10 3) of the top section sample at the remote Hietajärvi site was 0.9‰ and we suggest this represents the regional background isotope signature of atmospheric zinc. The deeper sections of the peat cores show isotopically heavier zinc than any potential atmospheric source, indicating that post depositional processes affected the isotopic records. The large variations encountered (up to 1.05‰ for δ 66Zn) and Rayleigh modelling imply that multiple fractionation of zinc during diagenetic alterations occurs and nutrient recycling alone cannot explain the fractionation pattern. We propose that zinc isotopes are amenable to identify different atmospheric zinc sources, including zinc derived from anthropogenic activities such as mining and smelting, but multiple biogeochemical

  8. Small impacts of atmospheric N deposition on ocean carbon cycle.

    NASA Astrophysics Data System (ADS)

    Buitenhuis, Erik; Suntharalingam, Parvadha; Kanakidou, Maria; Lamarque, Jean-Francois

    2014-05-01

    Simulations with the global ocean biogeochemical model PlankTOM10 (a Dynamic Green Ocean Model with 10 PFTs) forced with RCP8.5 scenario atmospheric N-deposition, show that by the 2090s the impact of a 22.07 Tg N/y (+175%) increase relative to the preindustrial control results in only a 1.5 Tg N/y increase in export @100m. The preindustrial control uses preindustrial N-deposition, while both simulations are forced with RCP8.5 climate. This small impact is due to compensating processes: a decrease in N2-fixation of 13.65 Tg N/y (-11%) and an increase in denitrification of 3.12 Tg N/y (+2%). The impact on N2O production is also quite small at 0.08 Tg N/y (+3.4%). The ocean N inventory increases by 4.52 Tg N/y, which is almost entirely inorganic N. The contribution of an increase in DOM inventory is negligeable (0.05 Tg N/y). There appears to be substantial subduction of inorganic carbon into the deep sea that is not used by phytoplankton, and therefore is presumably deposited at times and places that primary production is not nitrogen limited.

  9. Atmospheric deposition of organochlorine contaminants to Galveston Bay, Texas

    NASA Astrophysics Data System (ADS)

    Park, June-Soo; Wade, Terry L.; Sweet, Stephen

    Atmospheric monitoring of PCBs and chlorinated pesticides (e.g., HCHs, chlordanes, and DDTs) in Galveston Bay was conducted at Seabrook, Texas. Air and wet deposition samples were collected from 2 February 1995 and continued through 6 August 1996. Vapor total PCB ( tPCB) concentrations in air ranged from 0.21 to 4.78 ng m -3 with a dominance of tri-chlorinated PCBs. Dissolved tPCBs in rain ranged from 0.08 to 3.34 ng l -1, with tetra-chlorinated PCBs predominating. The predominant isomers found in air and rain were α- and γ-HCH, α- and γ-chlordanes, 4,4'-DDT, and dieldrin. The concentrations of PCBs and pesticides in the air and rain revealed no clear seasonal trend. Elevated levels of PCBs in the air occurred when temperatures were high and wind came from urban and industrialized areas (S, SW, NW, and W of the site). Concentrations of HCHs were elevated in April, May, and October, perhaps due to local and/or regional applications of γ-HCH (lindane). Other pesticides showed no notable temporal variation. When winds originated from the Gulf of Mexico (southeasterly), lower concentrations of organochlorines were detected in the air. The direct deposition rate (wet+dry) of PCBs to Galveston Bay (6.40 μg m -2 yr -1) was significantly higher than that of pesticides by a factor of 5-10. The net flux from gas exchange estimated for PCBs was from Galveston Bay water to the atmosphere (78 μg m -2 yr -1). Gas exchange of PCBs from bay water to the atmosphere was the dominant flux.

  10. Simulating soil atmosphere above a leaky CCS deposit

    NASA Astrophysics Data System (ADS)

    Schack-Kirchner, Helmer; Maier, Martin

    2015-04-01

    The escape of CO2 at the surface above a leaky geological deposit of carbon dioxide can be a fumarole-like point source or a subsurface plume distributing the gas over a larger area. In the latter case the lost CO2 from the deposit is added to the soil respiration as a quasi one-dimensional non-equimolar gas flux. Whether such an additional flux leads to inhibitory high levels of soil CO2 combined with a rather complete advective displacement of O2 or simply changes the diffusion characteristics in a more or less normal soil atmosphere depends for a given gas diffusivity and permeability on the ratio between the equimolar (respiratory) and the non-equimolar (leak based) flux of CO2. We tested the effecs by parametrization of a conceptual soil model consisting of capillaries filled either with soil air or water joining the soil air and the above-ground atmosphere. Soil atmosphere was simulated by combining a numerical solution of the Dusty-Gas model and a simple gas diffusion model in the water filled capillaries in an iterative process until Argon as noble gas is stagnant. The results show that in soils with high gas permeability even non-equimolar CO2 fluxes more than twice the soil respiration can be transferred to the surface without spectacular changes in soil-air pressure or O2 displacement. However, even low extra CO2 fluxes change significantly the gradient ratio of O2 and CO2 and stress soil aeration which is for many forest ecosystems a limiting factor of root growth.

  11. MEASURING CONTAMINANT RESUSPENSION RESULTING FROM SEDIMENT CAPPING

    EPA Science Inventory

    This Sediment Issue summarizes two studies undertaken at marine sites by the National Risk Management Research Laboratory of U.S. EPA to evaluate the resuspension of surface materials contaminated with polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) b...

  12. Estimated variability of National Atmospheric Deposition Program/Mercury Deposition Network measurements using collocated samplers

    USGS Publications Warehouse

    Wetherbee, G.A.; Gay, D.A.; Brunette, R.C.; Sweet, C.W.

    2007-01-01

    The National Atmospheric Deposition Program/Mercury Deposition Network (MDN) provides long-term, quality-assured records of mercury in wet deposition in the USA and Canada. Interpretation of spatial and temporal trends in the MDN data requires quantification of the variability of the MDN measurements. Variability is quantified for MDN data from collocated samplers at MDN sites in two states, one in Illinois and one in Washington. Median absolute differences in the collocated sampler data for total mercury concentration are approximately 11% of the median mercury concentration for all valid 1999-2004 MDN data. Median absolute differences are between 3.0% and 14% of the median MDN value for collector catch (sample volume) and between 6.0% and 15% of the median MDN value for mercury wet deposition. The overall measurement errors are sufficiently low to resolve between NADP/MDN measurements by ??2 ng??l-1 and ??2 ????m-2?? year-1, which are the contour intervals used to display the data on NADP isopleths maps for concentration and deposition, respectively. ?? Springer Science+Business Media B.V. 2007.

  13. Biodiversity Risks from Atmospheric Nitrogen Deposition in California

    NASA Astrophysics Data System (ADS)

    Weiss, S. B.

    2004-12-01

    Atmospheric nitrogen deposition alters structure and function of terrestrial ecosystems, because nitrogen availability is often limits overall productivity. These alterations can drive losses of biodiversity, as nitrophilous species increase in abundance and outcompete species adapted to more oligotrophic conditions. California is recognized as a "biodiversity hotspot," with a high fraction of endemic taxa with narrow ranges. A state-wide risk screening includes: 1) a 36 x 36 km map of total N-deposition for 2002, developed from the Community Multiscale Air Quality Model (CMAQ); 2) identification of sensitive habitat types from literature and local expertise; 3) overlay of a statewide vegetation map (FRAP); 4) overlay of species occurrence data from the California Natural Diversity Data Base (CNDDB); and 5)species life-history and habitat requirements. The CMAQ model indicates that 55,000 km2 (total area 405,205 km2) are exposed to >5 kg-N ha -1 year -1, and 10,000 km2 are exposed to >10 kg-N ha -1 year -1. Deposition hotspots include coastal urban areas (Los Angeles-San Diego, and the San Francisco Bay Area), the agricultural Central Valley, and parts of the Sierra Nevada foothills. The major known impact of N-deposition in California is increased growth and dominance of invasive annual grasses in low biomass ecosystems, such as coastal sage scrub, serpentine grassland, desert scrub, and vernal pools. For example, 800 km2 out of a total 6300 km2 of coastal sage scrub are exposed to more than 10 kg-N ha -1 year -1, primarily in Southern California. Of 225 federal and state "Threatened" and "Endangered" plant taxa, 101 are exposed on average to >5 kg-N ha -1 year -1. Of an additional 1022 plant taxa listed as "rare," 288 are exposed to >5 kg-N ha -1 year -1. Many of these highly exposed taxa are associated with sensitive habitat types and are vulnerable to annual grass invasions. This broad-scale screening outlines potential impacts on California's biodiversity, and

  14. Atmospheric transport and wet deposition of ammonium in North Carolina

    NASA Astrophysics Data System (ADS)

    Walker, John T.; Aneja, Viney P.; Dickey, David A.

    Wet deposition and transport analysis has been performed for ammonium (NH 4+) in North Carolina, USA. Multiple regression analysis is employed to model the temporal trend and seasonality in monthly volume-weighted mean NH 4+ concentrations in precipitation from 1983 to 1996 at six National Atmospheric Deposition Program/National Trends Network (NADP/NTN) sites. A significant ( p<0.01) increasing trend beginning in 1990, which corresponds to an annual concentration increase of approximately 9.5%, is detected at the rural Sampson County site (NC35), which is located within a densely populated network of swine and poultry operations. This trend is positively correlated with increasing ammonia (NH 3) emissions related to the vigorous growth of North Carolina's swine population since 1990, particularly in the state's Coastal Plain region. A source-receptor regression model, which utilizes weekly NH 4+ concentrations in precipitation in conjunction with boundary layer air mass back trajectories, is developed to statistically test for the influence of a particular NH 3 source region on NH 4+ concentrations at surrounding NADP/NTN sites for the years 1995-1996. NH 3 emissions from this source region, primarily evolving from swine and poultry operations, are found to increase NH 4+ concentration in precipitation at sites up to ≈80 km away. At the Scotland County (NC36) and Wake County (NC41) sites, mean NH 4+ concentrations show increases of at least 44% for weeks during which 25% or more back trajectories are influenced by this source region.

  15. Walking-induced particle resuspension in indoor environments

    NASA Astrophysics Data System (ADS)

    Qian, Jing; Peccia, Jordan; Ferro, Andrea R.

    2014-06-01

    Resuspension of particles indoors increases the risk of consequent exposure through inhalation and non-dietary ingestion. Studies have been conducted to characterize indoor particle resuspension but results do not always agree, and there are still many open questions in this field. This paper reviews the recent research of indoor resuspension and summarizes findings to answer six critical questions: 1) How does the resuspension sources compared to other indoor sources; 2) How is resuspension determined and how does the resuspension measure change as a function of particle size; 3) What are the primary resuspension mechanisms; 4) What are the factors affecting resuspension; 5) What are the knowledge gaps and future research directions in this area; and 6) How can what we know about resuspension guide better exposure mitigation strategies? From synthesized results, we conclude that resuspension is an important source for indoor particulate matter, compared with other indoor sources. Among all existing quantification terms of resuspension, resuspension fraction has the least variation in its estimates by explicitly defining surface loading and walking frequency, and thus is recommended to be adopted in future research over other terms. Resuspension increases with particle size in the range of 0.7-10 μm, although differences exist in resuspension estimates by orders of magnitude. The primary mechanism of particle resuspension involves rolling detachment, and the adhesive forces can be greatly reduced by microscopic surface roughness. Particle resuspension is by nature complicated, affected by various factors and their interactions. There are still many open questions to be answered to achieve an understanding of resuspension fundamentals. Given the complex and multidisciplinary nature of resuspension, understanding indoor particle resuspension behavior requires cross-disciplinary participation from experts in aerosol science, textile science, surface chemistry

  16. Biogeochemical context impacts seawater pH changes resulting from atmospheric sulfur and nitrogen deposition

    NASA Astrophysics Data System (ADS)

    Hagens, Mathilde; Hunter, Keith A.; Liss, Peter S.; Middelburg, Jack J.

    2014-02-01

    Seawater acidification can be induced both by absorption of atmospheric carbon dioxide (CO2) and by atmospheric deposition of sulfur and nitrogen oxides and ammonia. Their relative significance, interplay, and dependency on water column biogeochemistry are not well understood. Using a simple biogeochemical model we show that the initial conditions of coastal systems are not only relevant for CO2-induced acidification but also for additional acidification due to atmospheric acid deposition. Coastal areas undersaturated with respect to CO2 are most vulnerable to CO2-induced acidification but are relatively least affected by additional atmospheric deposition-induced acidification. In contrast, the pH of CO2-supersaturated systems is most sensitive to atmospheric deposition. The projected increment in atmospheric CO2 by 2100 will increase the sensitivity of coastal systems to atmospheric deposition-induced acidification by up to a factor 4, but the additional annual change in proton concentration is at most 28%.

  17. Atmospheric deposition of methanol over the Atlantic Ocean

    PubMed Central

    Yang, Mingxi; Nightingale, Philip D.; Beale, Rachael; Liss, Peter S.; Blomquist, Byron; Fairall, Christopher

    2013-01-01

    In the troposphere, methanol (CH3OH) is present ubiquitously and second in abundance among organic gases after methane. In the surface ocean, methanol represents a supply of energy and carbon for marine microbes. Here we report direct measurements of air–sea methanol transfer along a ∼10,000-km north–south transect of the Atlantic. The flux of methanol was consistently from the atmosphere to the ocean. Constrained by the aerodynamic limit and measured rate of air–sea sensible heat exchange, methanol transfer resembles a one-way depositional process, which suggests dissolved methanol concentrations near the water surface that are lower than what were measured at ∼5 m depth, for reasons currently unknown. We estimate the global oceanic uptake of methanol and examine the lifetimes of this compound in the lower atmosphere and upper ocean with respect to gas exchange. We also constrain the molecular diffusional resistance above the ocean surface—an important term for improving air–sea gas exchange models. PMID:24277830

  18. Water Deposition into Titan atmosphere from Saturn's E-ring

    NASA Astrophysics Data System (ADS)

    Juhasz, A.; Horanyi, M.; Kempf, S.; Srama, R.

    2013-12-01

    Cassini's discovery of the geologically active regions on the south polar region of Enceladus allowed the identification of these active plumes as the primary source of Saturn's E-ring. Micron and submicron sized ice particles are supplied from the plumes to sustain the entire E-ring. In situ measurements by the Cassini Cosmic Dust Analyzer (CDA) also led to the recognition that the E-ring extends way beyond its originally recognized limits of 4 - 8 Saturn radii (Rs), reaching beyond 20 Rs, engulfing Titan, Saturn's largest moon. Ice grains entrained in the plumes experience radiation pressure and plasma drag perturbations and their orbits slowly evolve outward. Simultaneously, the ice particles are exposed to energetic ion bombardment, leading to their mass loss due to sputtering. Initially micron sized particles from Enceladus take about 500 years to reach the orbit of Titan, arriving there as approximately 0.1-0.3 micron sized particles. Due to their large eccentricities, these small grains enter Titan's atmosphere with speeds v > 1 km/s,sufficiently fast to ablate, delivering on the order of 5 g/s of water. This presentation will discuss the resulting profiles of water vapor deposition rates as function of altitude in Titan's atmosphere.

  19. Distinguishing resuspension and advection signals in a hypertidal estuary

    NASA Astrophysics Data System (ADS)

    Todd, David; Souza, Alex; Jago, Colin

    2015-04-01

    Terrestrial material is supplied to an estuary system by the river, while marine material is supplied by the sea. Whether the estuary acts as a trap or a bypass zone for SPM (suspended particulate matter) depends upon the properties and dynamics of both the estuary, including the tidal and residual behaviour of the currents, and the SPM, including particle sizes and settling velocities and concentration gradients, which together control the dynamics, such as the trapping efficiency, of the estuary. Whether an SPM signal is regarded as being one of resuspension or advection depends upon the area of interest, and therefore distinguishing between resuspension and advection can be complex. Material that is resuspended within the area of study is regarded as resuspension, while that which is resuspended outside, but passes through, the area of interest, is regarded as advection. The results of a measurement campaign undertaken in a hypertidal UK estuary during the pre-spring bloom February-March and post-spring bloom May-June are presented utilising a combination of acoustic and optical instruments, moorings, and CTD stations. A characteristic asymmetric "twin peak" signal is present during both time periods, implying the presence of both resuspension and advection. This is confirmed through the use of harmonic analysis. A seasonal variation in the relative importance of the resuspension and advection components is seen between the two observation periods, with the small (<122µm) and large (>122µm) particles displaying different behaviours and providing a strong indication of the presence of flocculation. Approximate point flux calculations showed a reduction in the horizontal gradient of concentration, and subsequently the flood dominance of sediment transport, between May-June and February-March. This has been attributed to changes in biological activity and atmospheric forcing between the two observational periods. Ebb-dominant concentrations brought about by the

  20. The effect of four landscape features on atmospheric deposition to Hunter Mountain, New York

    SciTech Connect

    Weathers, K.C.

    1993-01-01

    Atmospheric deposition to montane ecosystems is higher than to adjacent lowlands. Because of the heterogeneous nature of mountainous landscapes, rates of deposition are likely to vary considerably with major landscape features. Estimates of total atmospheric deposition for mountains in the northeastern United States are wide-ranging and based on models that do not take into account landscape heterogeneity. Little had been known about the spatial variability of atmospheric deposition to these high elevation ecosystems. On Hunter Mountain in the Catskill Mountains, New York, four landscape features-(1) edges/gaps, (2) elevation, (3) aspect and (4) vegetation type-were identified as likely to control atmospheric deposition in mountainous terrain. Relative rates of atmospheric deposition, or enhancement factors, were measured across these landscape features by using lead in the forest floor as an indicator of total deposition, and, in the case of forest edges, also by making direct measurements of cloudwater deposition. These enhancement factors were used to model deposition to the Hunter Mountain landscape. Average deposition to the area above 1000 m was estimated to be 13% greater than to a nearby low elevation site. [open quotes]Hotspots[close quotes] were identified at high elevation, conifer forest edges where atmospheric deposition of pollutants and nutrients is up to 300% greater than a low-elevation forest. More detailed measurements of cloudwater deposition to an edge of a high elevation spruce forest revealed enhancement from 0- to 15-fold over the interior, with an average 3-fold increase. Sulfate flux in throughfall during cloud events was found to mirror cloudwater deposition and may be a useful tool to quantify patterns of atmospheric deposition in mountains. The data suggest current estimates of atmospheric deposition to mountainous terrain that do not include landscape heterogeneity may seriously underestimate loading of pollutants and nutrients.

  1. Sources, transport and deposition of iron in the global atmosphere

    NASA Astrophysics Data System (ADS)

    Wang, R.; Balkanski, Y.; Boucher, O.; Bopp, L.; Chappell, A.; Ciais, P.; Hauglustaine, D.; Peñuelas, J.; Tao, S.

    2015-06-01

    Atmospheric deposition of iron (Fe) plays an important role in controlling oceanic primary productivity. However, the sources of Fe in the atmosphere are not well understood. In particular, the combustion sources of Fe and the subsequent deposition to the oceans have been accounted for in only few ocean biogeochemical models of the carbon cycle. Here we used a mass-balance method to estimate the emissions of Fe from the combustion of fossil fuels and biomass by accounting for the Fe contents in fuel and the partitioning of Fe during combustion. The emissions of Fe attached to aerosols from combustion sources were estimated by particle size, and their uncertainties were quantified by a Monte Carlo simulation. The emissions of Fe from mineral sources were estimated using the latest soil mineralogical database to date. As a result, the total Fe emissions from combustion averaged for 1960-2007 were estimated to be 5.3 Tg yr-1 (90% confidence of 2.3 to 12.1). Of these emissions, 1, 27 and 72% were emitted in particles < 1 μm (PM1), 1-10 μm (PM1-10), and > 10 μm (PM> 10), respectively, compared to a total Fe emission from mineral dust of 41.0 Tg yr-1 in a log-normal distribution with a mass median diameter of 2.5 μm and a geometric standard deviation of 2. For combustion sources, different temporal trends were found in fine and medium-to-coarse particles, with a notable increase in Fe emissions in PM1 since 2000 due to an increase in Fe emission from motor vehicles (from 0.008 to 0.0103 Tg yr-1 in 2000 and 2007, respectively). These emissions have been introduced in a global 3-D transport model run at a spatial resolution of 0.94° latitude by 1.28° longitude to evaluate our estimation of Fe emissions. The modelled Fe concentrations as monthly means were compared with the monthly (57 sites) or daily (768 sites) measured concentrations at a total of 825 sampling stations. The deviation between modelled and observed Fe concentrations attached to aerosols at the

  2. Sources, transport and deposition of iron in the global atmosphere

    NASA Astrophysics Data System (ADS)

    Wang, R.; Balkanski, Y.; Boucher, O.; Bopp, L.; Chappell, A.; Ciais, P.; Hauglustaine, D.; Peñuelas, J.; Tao, S.

    2015-03-01

    Atmospheric deposition of iron (Fe) plays an important role in controlling oceanic primary productivity. However, the sources of Fe in the atmosphere are not well understood. In particular, the combustion sources of Fe and their deposition over oceans are not accounted for in current biogeochemical models of the carbon cycle. Here we used a mass-balance method to estimate the emissions of Fe from the combustion of fossil fuels and biomass by accounting for the Fe contents in fuel and the partitioning of Fe during combustion. The emissions of Fe attached to aerosols from combustion sources were estimated by particle size, and their uncertainties were quantified by a Monte Carlo simulation. The emissions of Fe from mineral sources were estimated using the latest soil mineralogical database to date. As a result, the total Fe emissions from combustion averaged for 1960-2007 were estimated to be 5.1 Tg yr-1 (90% confidence of 2.2 to 11.5). Of these emissions, 2, 33 and 65% were emitted in particles <1 μm (PM1), 1-10 μm (PM1-10), and >10 μm (PM>10), respectively, compared to total Fe emissions from mineral sources of 41.0 Tg yr-1. For combustion sources, different temporal trends were found in fine and medium-to-coarse particles, with a notable increase in Fe emissions in PM1 and PM1-10 since 2000 due to a rapid increase from motor vehicles. These emissions have been introduced in a global 3-D transport model run at a spatial resolution of of 0.94° latitude by 1.28° longitude to evaluate our estimation of Fe emissions. The modelled Fe concentrations were compared to measurements at 825 sampling stations. The deviation between modelled and observed Fe concentrations attached to aerosols at the surface was within a factor of two at most sampling stations, and the deviation was within a factor of 1.5 at sampling stations dominated by combustion sources. We analyzed the relative contribution of combustion sources to total Fe concentrations over different regions of the

  3. Atmospheric mercury deposition to Lake Michigan during the Lake Michigan Mass Balance Study.

    PubMed

    Landis, Matthew S; Keeler, Gerald J

    2002-11-01

    Wet and dry mercury (Hg) deposition were calculated to Lake Michigan using a hybrid receptor modeling framework. The model utilized mercury monitoring data collected during the Lake Michigan Mass Balance Study and the Atmospheric Exchange Over Lakes and Oceans Studytogether with high-resolution over-water meteorological date provided by the National Oceanic and Atmospheric Administration (July, 1994-October, 1995). Atmospheric deposition was determined to be the primary pathway for mercury inputto Lake Michigan, contributing approximately 84% of the estimated 1403 kg total annual input (atmospheric deposition + tributary input). Wet (10.6 microg m(-2)) and dry deposition (9.7 microg m(-2)) contributed almost equally to the annual atmospheric Hg deposition of 20.3 microg m(-2) (1173 kg). Re-emission of dissolved gaseous Hg from the lake was also significant (7.8 microg m(-2)), reducing the net atmospheric deposition to 12.5 microg m(-2) (720 kg). A strong urban influence was observed in the over-water mercury deposition estimates in the southern portion of the lake. The Chicago/Gary urban area was estimated to contribute approximately 20% (127 kg) of the annual atmospheric mercury deposition to Lake Michigan. The magnitude of local anthropogenic mercury sources in the Chicago/Gary urban area suggests that emission reductions could significantly reduce atmospheric mercury deposition into Lake Michigan. PMID:12433159

  4. Observational constraints of Polar Ice Deposits on Mars Atmospheric GCMs

    NASA Astrophysics Data System (ADS)

    Teodoro, L. F. A.; Elphic, R. C.; Hollingsworth, J. L.; Haberle, R. M.; Kahre, M. A.; Eke, V. R.; Roush, T. L.; Marzo, G. A.; Brown, A. J.; Feldman, W. C.; Maurice, S.

    2012-04-01

    Much of our current knowledge about Mars' climate and atmospheric global circulation stems from measurements taken by landers and orbiters. Thus for many years the details of the atmospheric circulation were studied using numerical global circulation models (GCMs) that have been successful in reproducing most of the available observations [1]. More than ever, GCMs will play a central role in analyzing the existing data and in planning and execution of upcoming missions. The Mars Odyssey Neutron Spectrometer (MONS) has enabled a comprehensive study of the overall distribution of hydrogen in the surface of Mars [2]. Deposits ranging between 20% and 100% Water-Equivalent Hydrogen (WEH) by mass are found pole-ward of 55 deg. latitude, while less H-rich deposits are found at lower latitudes. These results assume that the H distribution is uniform in the top meter of the martian soil. The Mars Reconnaissance Orbiter-Compact Reconnaissance Imaging Spectrometer for Mars (MRO-CRISM) has identified numerous locations on Mars where hydrous minerals occur [3]. The information collected by MRO-CRISM samples the top few mm's to cm's of the surface. This independent information can impose additional constrains on the 3-D H distribution inferred from the MONS data. For instance, the absence of a correlation between WEH wt% drawn from the MONS and CRISM data at a location where the neutron data indicate high WEH implies the presence of a 3-D structure that is characterized by a top layer with a low abundance of water, either ice or hydrated minerals, and some buried layers where the concentration of H is higher than that expected in a uniformly mixed layer. However, the spatial resolution of MONS and MRO-CRISM are ~550 km and ~20-200m, respectively. Hence, one must assure the MRO-CRISM and MONS data are on the same scales. The MRO-CRISM data can be re-binned to lower resolution, but additionally the MONS instrumental smearing must be properly understood and removed. Usually, in the

  5. Influence of atmospheric deposition on Okefenokee National Wildlife Refuge

    SciTech Connect

    Winger, P.V.; Lasier, P.J.; Jackson, B.P.

    1995-12-31

    Designation of Okefenokee National Wildlife Refuge (Georgia) as a Class 1 Air Quality Area affords mandatory protection of the airshed through permit-review processes for planned developments. Rainfall is the major source of water to the swamp, and potential impacts from developments in the airshed are high. To meet management needs for baseline information, chemical contributions from atmospheric deposition and partitioning of anions and cations in various matrices of the swamp, with emphasis on mercury and lead, were determined during this study. Chemistry of rainfall was measured on an event basis from one site and quarterly on surface water, pore water, floc, and sediment from four locations. A sediment core collected from the Refuge concentrations of 9 ng/L and 0.1 ng/L, respectively. Surface waters were acidic (pH 4.7--4.9), with average total and methyl mercury highly organic (dissolved organic carbon 35--50 mg/L). Total mercury was 1--3.5 ng/L in surface and pore water, and methyl mercury was 0.02--0.20 ng/L. Total mercury in sediments and floc was 100--200 ng/g dry weight, and methyl mercury was 4--16ng/g. Lead was 0--1.7 {micro}g/L in rainfall, not detectable in surface water, 3.4--5.4 {micro}g/L in pore water, and 3.9--4.9 mg/kg in floc and sediment. Historical patterns of mercury deposition showed an increase in total mercury from pre-1800 concentrations of 250 ng/g to 500 ng/g in 1950, with concentrations declining thereafter to present.

  6. Influence of atmospheric deposition on Okefenokee National Wildlife Refuge

    USGS Publications Warehouse

    Winger, P.V.; Lasier, P.J.; Jackson, B.P.

    1995-01-01

    Designation of Okefenokee National Wildlife Refuge (Georgia) as a Class I Air Quality Area affords mandatory protection of the airshed through permit-review processes for planned developments. Rainfall is the major source of water to the swamp, and potential impacts from developments in the airshed are high. To meet management needs for baseline information, chemical contributions from atmospheric deposition and partitioning of anions and cations in various matrices of the swamp, with emphasis on mercury and lead, were determined during this study. Chemistry of rainfall was measured on an event basis from one site and quarterly on surface water, pore water, floc, and sediment from four locations. A sediment core collected from the Refuge interior was sectioned, aged, and analyzed for mercury. Rainfall was acidic (pH 4.7-4.9), with average total and methyl mercury concentrations of 9 ng/L and 0.1 ng/L, respectively. Surface waters were acidic (pH 3.8-4.1), dilute (specific conductance 35-60 pS), and highly organic (dissolved organic carbon 35-50 mg/L). Total mercury was 1-3.5 ng/L in surface and pore water, and methyl mercury was 0.02-0.20 ng/L. Total mercury in sediments and floc was 100-200 ng/g dry weight, and methyl mercury was 4-16 ng/g. Lead was 0-1.7 pg/L in rainfall, not detectable in surface water, 3.4-5.4 pg/L in pore water, and 3.9-4.9 mg/kg in floc and sediment. Historical patterns of mercury deposition showed an increase in total mercury from pre-1800 concentrations of 250 ng/g to 500 ng/g in 1950, with concentrations declining thereafter to present.

  7. Atmospheric deposition of 7Be by rain events, incentral Argentina

    NASA Astrophysics Data System (ADS)

    Ayub, J. Juri; Di Gregorio, D. E.; Huck, H.; Velasco, H.; Rizzotto, M.

    2008-08-01

    Beryllium-7 is a natural radionuclide that enters into the ecosystems through wet and dry depositions and has numerous environmental applications in terrestrial and aquatic ecosystems. Atmospheric wet deposition of 7Be was measured in central Argentina. Rain traps were installed (1 m above ground) and individual rain events have been collected. Rain samples were filtered and analyzed by gamma spectrometry. The gamma counting was undertaken using a 40%-efficient p-type coaxial intrinsic high-purity natural germanium crystal built by Princeton Gamma-Tech. The cryostat was made from electroformed high-purity copper using ultralow-background technology. The detector was surrounded by 50 cm of lead bricks to provide shielding against radioactive background. The detector gamma efficiency was determined using a water solution with known amounts of chemical compounds containing long-lived naturally occurring radioisotopes, 176Lu, 138La and 40K. Due to the geometry of the sample and its position close to the detector, the efficiency points from the 176Lu decay, had to be corrected for summing effects. The measured samples were 400 ml in size and were counted curing one day. The 7Be detection limit for the present measurements was as low as 0.2 Bq l-1. Thirty two rain events were sampled and analyzed (November 2006-May 2007). The measured values show that the events corresponding to low rainfall (<20 mm) are characterized by significantly higher activity concentrations (Bq l-1). The activity concentration of each individual event varied from 0.8 to 3.5 Bq l-1, while precipitations varied between 4 and 70 mm. The integrated activity by event of 7Be was fitted with a model that takes into account the precipitation amount and the elapsed time between two rain events. The integrated activities calculated with this model show a good agreement with experimental values.

  8. Imbalanced atmospheric nitrogen and phosphorus depositions in China: Implications for nutrient limitation

    NASA Astrophysics Data System (ADS)

    Zhu, Jianxing; Wang, Qiufeng; He, Nianpeng; Smith, Melinda D.; Elser, James J.; Du, Jiaqiang; Yuan, Guofu; Yu, Guirui; Yu, Qiang

    2016-06-01

    Atmospheric wet nitrogen (N) and phosphorus (P) depositions are important sources of bioavailable N and P, and the input of N and P and their ratios significantly influences nutrient availability and balance in terrestrial as well as aquatic ecosystems. Here we monitored atmospheric P depositions by measuring monthly dissolved P concentration in rainfall at 41 field stations in China. Average deposition fluxes of N and P were 13.69 ± 8.69 kg N ha-1 a-1 (our previous study) and 0.21 ± 0.17 kg P ha-1 a-1, respectively. Central and southern China had higher N and P deposition rates than northwest China, northeast China, Inner Mongolia, or Qinghai-Tibet. Atmospheric N and P depositions showed strong seasonal patterns and were dependent upon seasonal precipitation. Fertilizer and energy consumption were significantly correlated with N deposition but less correlated with P deposition. The N:P ratios of atmospheric wet deposition (with the average of 77 ± 40, by mass) were negatively correlated with current soil N:P ratios in different ecological regions, suggesting that the imbalanced atmospheric N and P deposition will alter nutrient availability and strengthen P limitation, which may further influence the structure and function of terrestrial ecosystems. The findings provide the assessments of both wet N and P deposition and their N:P ratio across China and indicate potential for strong impacts of atmospheric deposition on broad range of terrestrial ecosystems.

  9. The investigation of atmospheric deposition distribution of organochlorine pesticides (OCPs) in Turkey

    NASA Astrophysics Data System (ADS)

    Cindoruk, S. Sıddık; Tasdemir, Yücel

    2014-04-01

    Atmospheric deposition is a significant pollution source leading to contamination of remote and clean sites, surface waters and soils. Since persistent organic pollutants (POPs) stay in atmosphere without any degradation, they can be transported and deposited to clean surfaces. Organochlorine pesticides are an important group of POPs which have toxic and harmful effects to living organisms and environment. Therefore, atmospheric deposition levels and characteristics are of importance to determine the pollution quantity of water and soil surfaces in terms of POPs. This study reports the distribution quantities of atmospheric deposition including bulk, dry, wet and air-water exchange of particle and gas phase OCPs as a result of 1-year sampling campaign. Atmospheric deposition distribution showed that the main mechanism for OCPs deposition is wet processes with percentage of 69 of total deposition. OCP compounds' deposition varied according to atmospheric concentration and deposition mechanism. HCH compounds were dominant pesticide species for all deposition mechanisms. HCH deposition constituted the 65% of Σ10OCPs.

  10. Patterns of atmospheric deposition to a mountain landscape in southeastern New York

    SciTech Connect

    Weathers, K.C.; Lovett, G.M.; Likens, G.E. )

    1994-06-01

    We postulate that in the Catskill Mts., of southeastern NY, patterns of atmospheric deposition across the landscape are regulated primarily by four landscape features: (1) edges and gaps; (2) elevation; (3) slope aspect; and (4) vegetation type. We measured relative rates of deposition associated with these features using Pb in the forest floor as an indicator of total deposition. Deposition enhancement factors generated by these measurements were used in a geographic information system to model deposition to the landscape of Hunter Mt. Average deposition in the area above 1000m elevation was estimated to be 13% greater than to nearby low-elevation sites. Combinations of the landscape features can create [open quotes]hotspots[close quotes] of deposition, for instance, high-elevation coniferous forest edges, where deposition can be 300% greater than to a low-elevation forest. These results illustrate the importance of considering landscape-level variation when modeling atmospheric deposition or extrapolating deposition measurements.

  11. Modeling and mapping of atmospheric mercury deposition in adirondack park, new york.

    PubMed

    Yu, Xue; Driscoll, Charles T; Huang, Jiaoyan; Holsen, Thomas M; Blackwell, Bradley D

    2013-01-01

    The Adirondacks of New York State, USA is a region that is sensitive to atmospheric mercury (Hg) deposition. In this study, we estimated atmospheric Hg deposition to the Adirondacks using a new scheme that combined numerical modeling and limited experimental data. The majority of the land cover in the Adirondacks is forested with 47% of the total area deciduous, 20% coniferous and 10% mixed. We used litterfall plus throughfall deposition as the total atmospheric Hg deposition to coniferous and deciduous forests during the leaf-on period, and wet Hg deposition plus modeled atmospheric dry Hg deposition as the total Hg deposition to the deciduous forest during the leaf-off period and for the non-forested areas year-around. To estimate atmospheric dry Hg deposition we used the Big Leaf model. The average atmospheric Hg deposition to the Adirondacks was estimated as 17.4 [Formula: see text]g m[Formula: see text] yr[Formula: see text] with a range of -3.7-46.0 [Formula: see text]g m[Formula: see text] yr[Formula: see text]. Atmospheric Hg dry deposition (370 kg yr[Formula: see text]) was found to be more important than wet deposition (210 kg yr[Formula: see text]) to the entire Adirondacks (2.4 million ha). The spatial pattern showed a large variation in atmospheric Hg deposition with scattered areas in the eastern Adirondacks having total Hg deposition greater than 30 μg m(-2) yr(-1), while the southwestern and the northern areas received Hg deposition ranging from 25-30 μg m(-2) yr(-1). PMID:23536871

  12. ROLE OF BIOTURBATION IN SEDIMENT RESUSPENSION AND ITS INTERACTION WITH PHYSICAL SHEARING

    EPA Science Inventory

    Marine benthic fauna play an important role in governing sediment-water relationships, including resuspension of particle-borne contaminants. onstant burrowing and subsurface deposit-feeding tend to eject sediment into overlying water, break up the cohesive structure of sediment-...

  13. Impact of Natural (Storm) and Anthropogenic (Trawl) Resuspension the Sediment Transport on the Gulf of Lion's Shelf (NW Mediterranean)

    NASA Astrophysics Data System (ADS)

    Ferre, B.; Durrieu de Madron, X.; Estournel, C.; Ulses, C.; Le Corre, G.

    2006-12-01

    Modern sediment deposits on continental margins form a vast reservoir of particulate matter that is regularly affected by resuspension processes. On shelves with strong fishing activity, resuspension by bottom trawling processes can modify the scale of natural disturbance by waves and currents. Recent field data shows that the impact of bottom trawls on the resuspension of the fine sediments per unit surface is comparable with that of the largest storms. We assessed the impact of both natural and anthropogenic processes on the dispersal of river-borne particles and shelf sediments on the Gulf of Lion's Shelf. Realistic numerical simulations of resuspension and transport forced by currents and waves or by a fleet of bottom trawlers were developed. Simulations were conducted for a 16-month period to characterize the seasonal variability. The sediment dynamics takes into account bed armoring, ripple geometry and the cohesive and non-cohesive characteristics of the sediment. Essential but uncertain parameters (clay content, erosion fluxes and critical shear stress for cohesive sediment) were set with existing data. Resuspension by waves and currents is controlled by the shear stress, whereas resuspension by the bottom trawler fleet is controlled by its density and distribution. Natural resuspension by waves and currents mostly occurs during short winter episodes, and is concentrated on the inner-shelf. Trawling-induced resuspension, in contrast, occurs regularly throughout the year and is concentrated on the outer shelf. The total annual net resuspension by trawls (8×106 T y-1 is four orders of magnitude lower than the resuspension induced by waves and currents (4×1010 T y-1. However, because trawled regions are located on the outer shelf, closer to the continental slope, export of fine sediment resuspended by trawls (0.6×106 T y-1 is only one order of magnitude lower than export associated with natural resuspension (8×106 T y-1. A simulation combining both

  14. Atmospheric deposition of chlorinated organophosphate flame retardants (OFR) onto soils

    NASA Astrophysics Data System (ADS)

    Mihajlović, Ivana; Fries, Elke

    2012-09-01

    This study highlights the influence of dry and wet deposition on concentrations of chlorinated organophosphate flame retardants (OFR) in soil. Soil samples were collected in 2010/11 during a period of snow falling to snow melting, a period of rainfall and a dry period. Snow and rainwater samples were also collected from the soil sampling site. Tris(2-chloroethyl)phosphate (TCEP), tris(2-chloroisopropyl)phosphate (TCPP) and tris(1,3-dichloro-2-propyl)phosphate (TDCP) were analysed in soil samples using a combination of Twisselmann extraction and solid-phase microextraction (SPME), followed by gas chromatography-mass spectrometry (GC-MS). SPME/GC-MS was applied to analyse TCEP, TCPP and TDCP in aqueous samples. Concentrations of TCEP were between 236 and 353 ng L-1 in snow and 78 and 234 ng L-1 in rain. TCPP concentrations were between 226 and 284 ng L-1 in snow and 371 and 385 ng L-1 in rain. In soil samples, concentrations ranged from 5.07 to 23.48 ng g-1 dry weight (dwt) for TCEP and 5.66 to 19.82 ng g-1 dwt for TCPP. Concentrations of TDCP in rainwater and snow samples were rather low (46 and 100 ng L-1, respectively); concentrations of TDCP were below the limit of detection in soil samples. Snow melting caused enhanced soil concentrations of TCEP and TCPP, but greater effect of snow melting was observed for TCEP than for TCPP soil concentrations. No significant correlation between precipitation amounts and soil concentrations was observed. The influence of wet deposition on soil contents of TCEP and TCPP may be covered by volatilisation or by the mobility of both compounds in soil and their transport to deeper soil zones with seepage water. Snow was found to be a more efficient scavenger and transporter of chlorinated OFR into soil than rainwater. During dry weather, the soil concentrations of both compounds seemed to be driven mainly by air concentrations, which are determined by source emission strengths and photochemical degradation in the atmosphere. Values

  15. Impacts of atmospheric nutrient deposition on marine productivity: Roles of nitrogen, phosphorus, and iron

    NASA Astrophysics Data System (ADS)

    Okin, Gregory S.; Baker, Alex R.; Tegen, Ina; Mahowald, Natalie M.; Dentener, Frank J.; Duce, Robert A.; Galloway, James N.; Hunter, Keith; Kanakidou, Maria; Kubilay, Nilgun; Prospero, Joseph M.; Sarin, Manmohan; Surapipith, Vanisa; Uematsu, Mitsuo; Zhu, Tong

    2011-06-01

    Nutrients are supplied to the mixed layer of the open ocean by either atmospheric deposition or mixing from deeper waters, and these nutrients drive nitrogen and carbon fixation. To evaluate the importance of atmospheric deposition, we estimate marine nitrogen and carbon fixation from present-day simulations of atmospheric deposition of nitrogen, phosphorus, and iron. These are compared with observed rates of marine nitrogen and carbon fixation. We find that Fe deposition is more important than P deposition in supporting N fixation. Estimated rates of atmospherically supported carbon fixation are considerably lower than rates of marine carbon fixation derived from remote sensing, indicating the subsidiary role atmospheric deposition plays in total C uptake by the oceans. Nonetheless, in high-nutrient, low-chlorophyll areas, the contribution of atmospheric deposition of Fe to the surface ocean could account for about 50% of C fixation. In marine areas typically thought to be N limited, potential C fixation supported by atmospheric deposition of N is only ˜1%-2% of observed rates. Although these systems are N-limited, the amount of N supplied from below appears to be much larger than that deposited from above. Atmospheric deposition of Fe has the potential to augment atmospherically supported rates of C fixation in N-limited areas. In these areas, atmospheric Fe relieves the Fe limitation of diazotrophic organisms, thus contributing to the rate of N fixation. The most important uncertainties in understanding the relative importance of different atmospheric nutrients are poorly understood speciation and solubility of Fe as well as the N:Fe ratio of diazotrophic organisms.

  16. The Measurement of Atmospheric Concentrations and Deposition of Semi-Volatile Organic Compounds.

    ERIC Educational Resources Information Center

    Lee, David S.; Nicholson, Ken W.

    1994-01-01

    Provides a physical description of semivolatile organic compounds (SVOCs), both in terms of their characteristic nature in the atmosphere and the processes which control their deposition. Contains a summary of the requirements for a full assessment of atmospheric SVOCs and their deposition. (LZ)

  17. The role of "pump action" in coastal and estuarine sediment resuspension

    NASA Astrophysics Data System (ADS)

    Jia, Y.; Zhang, S.

    2014-12-01

    Most of the sediment into sea carried by rivers deposited near the estuary,forming the subaqueous delta. However,previous researches has shown that sediment into sea carried by many rivers all over the world always forms a large scale of distribution along the estuarine coastal areas that thousands of kilometers away from the estuary. Resuspension of estuarine and coastal sediment plays an important role in the sediment long distance transport into sea. At present, it is widely recognized that sediment resuspension is caused by the wave and current scouring action on the surface of the seabed. This paper explored the process and mechanism of seabed sediment resuspension through flume simulation experiments; developed a conclusion that sediment resuspension is not only from the seabed surface, there is still a considerable part of sediments coming from the internal seabed through seepage "pump action";The proportion of the latter part in sediment resuspension is related to wave height, this experiment concluded that 5、10、15cm wave heights respectively accounted for 30.5%,43.8%,47.9%;The "pump action" is induced by the accumulation of excess pore water pressure inside the soil bed under the action of wave loading.

  18. 210Po and 210Pb as Tracers of Particle Cycling and Resuspension in a Dynamic Freshwater System: Case Study from the Clinton River, Southeast Michigan

    NASA Astrophysics Data System (ADS)

    Mudbidre, R.; Baskaran, M. M.; Schweitzer, L.

    2013-12-01

    Polonium-210 and 210Pb are constantly delivered to the surface waters through atmospheric deposition with a 210Po/210Pb activity ratio (AR) of < 0.10. Freshly produced suspended particles in surface waters are ';tagged' with this ratio which tends to grow towards the secular equilibrium value of 1.0. This disequilibrium between 210Po and 210Pb in freshwater system with a relatively short hydrological residence time can be utilized to quantify sediment resuspension rates and to investigate the extent of recycling of sedimentary particulate matter. From the measurements of 210Po and 210Pb in particulate matter collected in sediment traps and surficial bottom sediments at 5 different sites in the Clinton River in southeast Michigan over a period of 6 months (April - September, 2005) and subsequent modeling of these data, we report the following: i) The direct atmospheric deposition of 210Po and 210Pb collected in the sediment trap materials accounted for 1% and 0.1%, respectively, of the total deposited in the sediment trap; ii) The ranges and mean values of the 210Po and 210Pb in the sediment trap material and bottom sediments are comparable, with near identical 210Po/210Pb ratios, indicating that most of the trapped 210Po and 210Pb were delivered by the resuspension of bottom sediments; iii) The particle residence times varied from 0.3 to 4 days for 210Pb and 0.9 to 13.4 days for 210Po; and iv) The sediment resuspension rates calculated via single box model approach yielded resuspension rates ranging from 0.2 to 14.2 g cm-2 yr-1 using 210Pb and 0.1 to 1.0 g cm-2 yr-1 using 210Po. We propose that the distribution of 210Bi (and 210Bi/210Pb) would provide better insight on particle cycling in short-time scales and a brief discussion will be presented on the utility of 210Bi/210Pb ratio as a powerful tool for short-term particle cycling and as tracers of POC, PON export studies in deeper freshwater lakes.

  19. Atmospherically deposited trace metals from bulk mineral concentrate port operations.

    PubMed

    Taylor, Mark Patrick

    2015-05-15

    Although metal exposures in the environment have declined over the last two decades, certain activities and locations still present a risk of harm to human health. This study examines environmental dust metal and metalloid hazards (arsenic, cadmium, lead and nickel) associated with bulk mineral transport, loading and unloading port operations in public locations and children's playgrounds in the inner city of Townsville, northern Queensland. The mean increase in lead on post-play hand wipes (965 μg/m(2)/day) across all sites was more than 10-times the mean pre-play loadings (95 μg/m(2)/day). Maximum loading values after a 10-minute play period were 3012 μg/m(2), more than seven times the goal of 400 μg/m(2) used by the Government of Western Australia (2011). Maximum daily nickel post-play hand loadings (404 μg/m(2)) were more than 26 times above the German Federal Immission Control Act 2002 annual benchmark of 15 μg/m(2)/day. Repeat sampling over the 5-day study period showed that hands and surfaces were re-contaminated daily from the deposition of metal-rich atmospheric dusts. Lead isotopic composition analysis of dust wipes ((208)Pb/(207)Pb and (206)Pb/(207)Pb) showed that surface dust lead was similar to Mount Isa type ores, which are exported through the Port of Townsville. While dust metal contaminant loadings are lower than other mining and smelting towns in Australia, they exceeded national and international benchmarks for environmental quality. The lessons from this study are clear - even where operations are considered acceptable by managing authorities, targeted assessment and monitoring can be used to evaluate whether current management practices are truly best practice. Reassessment can identify opportunities for improvement and maximum environmental and human health protection. PMID:25706750

  20. Atmospheric nitrogen compounds II: emissions, transport, transformation, deposition and assessment

    NASA Astrophysics Data System (ADS)

    Aneja, Viney P.; Roelle, Paul A.; Murray, George C.; Southerland, James; Erisman, Jan Willem; Fowler, David; Asman, Willem A. H.; Patni, Naveen

    The Atmospheric Nitrogen Compounds II: Emissions, Transport, Transformation, Deposition and Assessment workshop was held in Chapel Hill, NC from 7 to 9 June 1999. This international conference, which served as a follow-up to the workshop held in March 1997, was sponsored by: North Carolina Department of Environment and Natural Resources; North Carolina Department of Health and Human Services, North Carolina Office of the State Health Director; Mid-Atlantic Regional Air Management Association; North Carolina Water Resources Research Institute; Air and Waste Management Association, RTP Chapter; the US Environmental Protection Agency and the North Carolina State University (College of Physical and Mathematical Sciences, and North Carolina Agricultural Research Service). The workshop was structured as an open forum at which scientists, policy makers, industry representatives and others could freely share current knowledge and ideas, and included international perspectives. The workshop commenced with international perspectives from the United States, Canada, United Kingdom, the Netherlands, and Denmark. This article summarizes the findings of the workshop and articulates future research needs and ways to address nitrogen/ammonia from intensively managed animal agriculture. The need for developing sustainable solutions for managing the animal waste problem is vital for shaping the future of North Carolina. As part of that process, all aspects of environmental issues (air, water, soil) must be addressed as part of a comprehensive and long-term strategy. There is an urgent need for North Carolina policy makers to create a new, independent organization that will build consensus and mobilize resources to find technologically and economically feasible solutions to this aspect of the animal waste problem.

  1. PORTABLE DEVICE FOR MEASURING SEDIMENT RESUSPENSION

    EPA Science Inventory

    A portable device for measuring sediment resuspension has been developed. he device consists of a cylindrical chamber inside of which a horizontal grid oscillates vertically. he sediments whose properties are to be determined are placed at the bottom of the chamber with water ove...

  2. Dust Resuspension due to Idealized Foot Motion

    NASA Astrophysics Data System (ADS)

    Sheth, Ritesh

    2005-11-01

    The air quality is affected by amount and types of particulate contaminants that are suspended in the air. The resuspension phenomena occur through two mechanisms: mechanical, where kinetic energy is transferred through direct contact from an impacting body or a vibrating surface, and aerodynamic, where dust particles are resuspended by the flow disturbance generated by the body. In this presentation we focus on aerodynamic resuspension of particles caused by walking. The foot movement is idealized and is either towards or away from a floor without touching it. As a first approach, a 15 cm diameter disk having the equivalent area to that of a human foot is used. The ``foot'' movement is driven vertically by a linear servo motor that controls the velocity, acceleration, stroke and deceleration (a typical vertical velocity is 0.5-1.0 m/s). A thin layer of dust is spread on a table relative to which the disk is allowed to move up and down. Flow visualizations show that both the upward and downward movements of the disk play an important role in the dust resuspension. A clear effect of radial jet and vortex dynamics on the particle resuspension is observed during the downward motion. In the wake of the rising disk, the particles were entrained upwards as a starting ring vortex formed. Quantitative PIV measurements will be performed to help further analyze the flow structure of this flow configuration.

  3. Integrated Assessment of Ecosystem Effects of Atmospheric Deposition

    EPA Science Inventory

    Ecosystems obtain a portion of their nutrients from the atmosphere. Following the Industrial Revolution, however, human activities have accelerated biogeochemical cycles, greatly enhancing the transport of substances among the atmosphere, water, soil, and living things. The atmos...

  4. Impacts of atmospheric deposition on ocean biogeochemistry - moving beyond iron (Invited)

    NASA Astrophysics Data System (ADS)

    Paytan, A.

    2013-12-01

    Atmospheric deposition of trace elements, nutrients, organic compounds, living cells and particles to the ocean can significantly modify seawater chemistry and influence oceanic productivity and biogeochemistry. However, mounting evidence suggests that the response of living organisms to atmospheric deposition depends on the chemical and physical composition of the aerosols and varies across different species and ecosystems. Responses are also different depending on oceanographic setting and season. Results from models and incubation experiments with natural plankton assemblages at a wide range of marine locations will be presented to illustrate the variable impacts of atmospheric deposition. Utilization of nutrients and susceptibility to metal toxicity was different among different taxa and at different sites, suggesting that aerosol deposition could potentially alter patterns of marine primary production and phytoplankton community structure. Changes in atmospheric deposition and aerosol composition that are impacted from natural and anthropogenic change could therefore have effects on ocean chemistry and productivity with potential feedbacks to the carbon cycle.

  5. Can sulfate fluxes in forest canopy throughfall be used to estimate atmospheric sulfur deposition

    SciTech Connect

    Lindberg, S.E.; Garten, C.T. Jr. ); Cape, J.N. ); Ivens, W. )

    1991-01-01

    The flux of sulfate is forest throughfall and stemflow (the sum of which is designated here as TF) may be an indicator of the atmospheric deposition of S, particularly if foliar leaching of internal plant S is small relative to washoff of deposition. Extensive data from 13 forests indicate that annual sulfate fluxes in TF and in atmospheric deposition are very similar, and recent studies with {sup 35}S tracers indicate that leaching is only a few percent of total TF. However, some short-term deposition/TF comparisons show large differences, and there remain questions about interpretation of tracer results. Considering the data, we conclude that TF may be used under some conditions to estimate deposition within acceptable uncertainty limits, but that some assumptions need further testing. If TF does reflect deposition, these data suggest that commonly used methods and models seriously underestimate total S deposition at some sites. 39 refs. ,4 figs., 1 tab.

  6. Trace metal determination in total atmospheric deposition in rural and urban areas.

    PubMed

    Azimi, Sam; Ludwig, Alexandre; Thévenot, Daniel R; Colin, Jean-Louis

    2003-06-01

    The wet, dry and total atmospheric depositions of some metals (Al, Cd, Cr, Cu, Fe, Na, Pb and Zn) were sampled at two sites and atmospheric fallout fluxes were determined for these locations. This work, led by two different research groups, allowed to reach two main goals: to define a simple analytical procedure to secure accurate shipboard sampling and analysis of atmospheric deposition, and to assess anthropogenic impacts of heavy metals to the environment. The first step about the validation step showed that the prevalent deposition type was dry deposition which represents 40, 60 and 80% for Cd, Cu and Pb, respectively. This prevalence of dry deposition in total atmospheric fallout supported the necessity of funnel wall rinsing which contains 30, 50 and 40% of collected Cd, Cu and Pb, respectively. Moreover, the reproducibility of atmospheric deposition collection was determined. The second step was performed by comparing two sampling sites. A rural sampling site, situated in Morvan's regional park (250 km south-east of Paris), was chosen for its isolation from any local and regional contamination sources. Fluxes obtained in this area were compared with those obtained at an urban site (Créteil, suburb of Paris) allowing comparison between urban and rural areas and demonstrating the impact of anthropogenic activities on atmospheric deposition of Cr, Cu and Pb. PMID:12738217

  7. Atmospheric dry deposition of trace elements at a site on Asian-continent side of Japan

    NASA Astrophysics Data System (ADS)

    Sakata, Masahiro; Asakura, Kazuo

    2011-02-01

    The sources of dry-deposited trace elements (As, Cd, Cr, Cu, Mn, Ni, Pb, Sb and V) and the factors controlling their dry deposition fluxes were investigated on the basis of two-year observations (April 2004-March 2006) at a site on the Asian-continent side of Japan, which has been strongly affected by air pollutants from the Asian continent. Dry deposition sampling was conducted using a water surface sampler connected to a wet-only precipitation sampler. The dry deposition of As, Cd, Pb and Sb showed a small contribution to atmospheric deposition (0.25-0.44 as ratios of annual dry/wet deposition fluxes). Moreover, the dry deposition fluxes of those elements increased negligibly during the period when their atmospheric particulate matter (PM) concentrations increased owing to transport from the Asian continent. Thus, the dry deposition of As, Cd, Pb and Sb from the Asian continent was not significant, because their overall dry deposition velocities are relatively low (mostly <1 cm s -1). Conversely, the annual dry deposition fluxes of Cr, Cu and Ni exceeded their annual wet deposition fluxes (2.5-12.4 as ratios of annual dry/wet deposition fluxes). Those overall dry deposition velocities were much higher (3.2-9.7 cm s -1), and the crustal enrichment factors (EFs) frequently exceeded ten. These results suggest that the dry deposition of Cr, Cu and Ni is dominated by considerably coarse particles from local anthropogenic sources. For Mn and V, the dry and wet depositions contributed almost equally to the annual deposition fluxes. Their monthly dry deposition fluxes correlated significantly with that of Al ( P < 0.001), and the EFs were close to unity, suggesting a large contribution of background soil to their dry deposition. The dry deposition fluxes of all the trace elements were dependent not on their atmospheric PM concentrations but on their overall dry deposition velocities. The particle size distributions of the elements in the atmosphere are likely the most

  8. Effect of the resuspension technique on distribution of the heavy metals in sediment and suspended particulate matter.

    PubMed

    Pourabadehei, Mehdi; Mulligan, Catherine N

    2016-06-01

    Harbour areas play important roles in the economy worldwide. Human activities, however, in those areas, generate contamination, which mostly accumulates in sediments. On the other hand, harbour areas have been facing deposition of significant amounts of sediment each year. As a consequence, shallowness and accumulation of contaminants in sediment become challenging issues in harbours. Among the various management options for remediation of contaminated sediments in harbours, resuspension technique was introduced as a new approach to address those issues. The concept of the resuspension method is that finer sediments have a greater tendency to adsorb the contamination. Therefore, removing the finer sediments instead of dredging the whole contaminated area is the main goal of the resuspension technique. The objective of this paper was to evaluate the effect of the resuspension method on reducing the concentration of contamination and distribution of heavy metals in sediment and suspended particulate matter. The resuspension method was successful in reducing the concentration of seven selected heavy metals (Cr, Ni, Cu, Zn, As, Cd and Pb) by removing just 4% of the contaminated sediment. The contamination intensity in the sediment, presented by geoaccumulation index, was reduced for Cd and Pb as the main contaminants by 26 and 28 percent and the rest of the selected heavy metals returned to the natural level. The results of the sequential extraction tests and enrichment factor implied that the resuspension technique is capable of decreasing the risk of remobilization of heavy metals in the aquatic ecosystem. PMID:27010167

  9. Temporal Variation in Atmospheric Phosphorus Transport and Deposition to the Yucatan Peninsula: Local and Remote Sources

    NASA Astrophysics Data System (ADS)

    Das, R.

    2011-12-01

    Atmospheric phosphorus (P) inputs are rarely considered in models of terrestrial P cycling, but may be critical in balancing losses of P from ecosystems over the long-term, especially in the tropics. Several authors have suggested that forests in the Amazon basin, Hawaiian and Caribbean islands may be sustained by atmospheric P inputs from long-distance dust transport and other sources, but relatively few studies combine field measurements in a region with remote sensing or modeling approaches to quantify atmospheric P inputs. We use measurements of P in atmospheric bulk deposition collected periodically between 2006 and 2011 in a tropical dry forest in the southern Yucatan peninsula and compare these with remote sensing and atmospheric transport modeling estimates. There is a seasonal pattern in P deposition, with the greatest deposition occurring between April and August, when local biomass burning is greatest. Saharan dust transport to the region occurs between June and August, and is an important contributor to atmospheric P deposition. There is also interannual variation in atmospheric P deposition that is driven by variations in biomass burning and dust transport. We evaluate the importance of long-distance dust transport to the Yucatan as a source of P relative to other atmospheric inputs and losses, and its importance to ecosystem productivity.

  10. 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

  11. 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

  12. 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...

  13. ANN application for prediction of atmospheric nitrogen deposition to aquatic ecosystems.

    PubMed

    Palani, Sundarambal; Tkalich, Pavel; Balasubramanian, Rajasekhar; Palanichamy, Jegathambal

    2011-06-01

    The occurrences of increased atmospheric nitrogen deposition (ADN) in Southeast Asia during smoke haze episodes have undesired consequences on receiving aquatic ecosystems. A successful prediction of episodic ADN will allow a quantitative understanding of its possible impacts. In this study, an artificial neural network (ANN) model is used to estimate atmospheric deposition of total nitrogen (TN) and organic nitrogen (ON) concentrations to coastal aquatic ecosystems. The selected model input variables were nitrogen species from atmospheric deposition, Total Suspended Particulates, Pollutant Standards Index and meteorological parameters. ANN models predictions were also compared with multiple linear regression model having the same inputs and output. ANN model performance was found relatively more accurate in its predictions and adequate even for high-concentration events with acceptable minimum error. The developed ANN model can be used as a forecasting tool to complement the current TN and ON analysis within the atmospheric deposition-monitoring program in the region. PMID:21481425

  14. MEAD: an interdisciplinary study of the marine effects of atmospheric deposition in the Kattegat.

    PubMed

    Spokes, L; Jickells, T; Weston, K; Gustafsson, B G; Johnsson, M; Liljebladh, B; Conley, D; Ambelas-Skjødth, C; Brandt, J; Carstensen, J; Christiansen, T; Frohn, L; Geernaert, G; Hertel, O; Jensen, B; Lundsgaard, C; Markager, S; Martinsen, W; Møller, B; Pedersen, B; Sauerberg, K; Sørensen, L L; Hasager, C C; Sempreviva, A M; Pryor, S C; Lund, S W; Larsen, S; Tjernström, M; Svensson, G; Zagar, M

    2006-04-01

    This paper summarises the results of the EU funded MEAD project, an interdisciplinary study of the effects of atmospheric nitrogen deposition on the Kattegat Sea between Denmark and Sweden. The study considers emissions of reactive nitrogen gases, their transport, transformations, deposition and effects on algal growth together with management options to reduce these effects. We conclude that atmospheric deposition is an important source of fixed nitrogen to the region particularly in summer, when nitrogen is the limiting nutrient for phytoplankton growth, and contributes to the overall eutrophication pressures in this region. However, we also conclude that it is unlikely that atmospheric deposition can, on its own, induce algal blooms in this region. A reduction of atmospheric nitrogen loads to this region will require strategies to reduce emissions of ammonia from local agriculture and Europe wide reductions in nitrous oxide emissions. PMID:16271430

  15. ESTIMATING GASEOUS EXCHANGES BETWEEN THE ATMOSPHERE AND PLANTS USING A COUPLED BIOCHEMICAL DRY DEPOSITION MODEL

    EPA Science Inventory

    To study gaseous exchanges between the soil, biosphere and atmosphere, a biochemical model was coupled with the latest version of Meyers Multi-Layer Deposition Model. The biochemical model describes photosynthesis and respiration and their coupling with stomatal resistance for...

  16. Atmospheric nitrogen in the Mississippi River Basin - Amissions, deposition and transport

    USGS Publications Warehouse

    Lawrence, G.B.; Goolsby, D.A.; Battaglin, W.A.; Stensland, G.J.

    2000-01-01

    Atmospheric deposition of nitrogen has been cited as a major factor in the nitrogen saturation of forests in the north-eastern United States and as a contributor to the eutrophication of coastal waters, including the Gulf of Mexico near the mouth of the Mississippi River. Sources of nitrogen emissions and the resulting spatial patterns of nitrogen deposition within the Mississippi River Basin, however, have not been fully documented. An assessment of atmospheric nitrogen in the Mississippi River Basin was therefore conducted in 1998-1999 to: (1) evaluate the forms in which nitrogen is deposited from the atmosphere; (2) quantify the spatial distribution of atmospheric nitrogen deposition throughout the basin; and (3) relate locations of emission sources to spatial deposition patterns to evaluate atmospheric transport. Deposition data collected through the NADP/NTN (National Atmospheric Deposition Program/National Trends Network) and CASTNet (Clean Air Status and Trends Network) were used for this analysis. NO(x) Tier 1 emission data by county was obtained for 1992 from the US Environmental Protection Agency (Emissions Trends Viewer CD, 1985-1995, version 1.0, September 1996) and NH3 emissions data was derived from the 1992 Census of Agriculture (US Department of Commerce. Census of Agriculture, US Summary and County Level Data, US Department of Commerce, Bureau of the Census. Geographic Area series, 1995:1b) or the National Agricultural Statistics Service (US Department of Agriculture. National Agricultural Statistics Service Historical Data. Accessed 7/98 at URL, 1998. http://www.usda.gov/nass/pubs/hisdata.htm). The highest rates of wet deposition of NO3- were in the north-eastern part of the basin, downwind of electric utility plants and urban areas, whereas the highest rates of wet deposition of NH4+ were in Iowa, near the center of intensive agricultural activities in the Midwest. The lowest rates of atmospheric nitrogen deposition were on the western (windward

  17. Atmospheric mercury deposition on Fanjing Mountain Nature Reserve, Guizhou, China.

    PubMed

    Xiao, Z; Sommar, J; Lindqvist, O; Tan, H; He, J

    1998-04-01

    Fanjing Mountain Nature Reserve (FMNR) is surrounded with several Hg emission sources within distances of 100-200 km. At the two sites studied, Tongren and Danzai, Hg emission and deposition fluxes, Hg concentration in the air, soil and other samples are all several hundred times higher than at other relatively clean areas. Hg accumulation in soil and moss at FMNR varies with the sampling heights. Total Hg deposition to this area has been estimated to be 115 micrograms m-2 y-1 using moss bag technique. Dry deposition was determined to be about 5.2 micrograms m-2 month-1 during March to June, corresponding to more than 50% of the total deposition. PMID:9566295

  18. Chinese coastal seas are facing heavy atmospheric nitrogen deposition

    NASA Astrophysics Data System (ADS)

    Luo, X. S.; Tang, A. H.; Shi, K.; Wu, L. H.; Li, W. Q.; Shi, W. Q.; Shi, X. K.; Erisman, J. W.; Zhang, F. S.; Liu, X. J.

    2014-09-01

    As the amount of reactive nitrogen (N) generated and emitted increases the amount of N deposition and its contribution to eutrophication or harmful algal blooms in the coastal zones are becoming issues of environmental concern. To quantify N deposition in coastal seas of China we selected six typical coastal sites from North to South in 2011. Concentrations of NH3, HNO3, NO2, particulate NH4+ (pNH4+) and pNO3- ranged from 1.97- 4.88, 0.46 -1.22, 3.03 -7.09, 2.24 - 4.90 and 1.13-2.63 μg N m-3 at Dalian (DL), Changdao (CD), Linshandao (LS), Fenghua (FH), Fuzhou (FZ), and Zhanjiang (ZJ) sites, respectively. Volume-weighted NO3--N and NH4+-N concentrations in precipitation varied from 0.46 to 1.67 and 0.47 to 1.31 mg N L-1 at the six sites. Dry, wet and total deposition rates of N were 7.8-23.1, 14.2-25.2 and 22.0 - 44.6 kg N ha-1 yr-1 across the six coastal sites. Average N dry deposition accounted for 45.4% of the total deposition and NH3 and pNH4+ contributed to 76.6% of the dry deposition. If we extrapolate our total N deposition of 33.9 kg N ha-1 yr-1 to the whole Chinese coastal sea area (0.40 million km2), total N deposition amounts to 1.36 Tg N yr-1, a large external N input to surrounding marine ecosystems.

  19. Modeling atmospheric deposition using a stochastic transport model

    SciTech Connect

    Buckley, R.L.

    1999-12-17

    An advanced stochastic transport model has been modified to include the removal mechanisms of dry and wet deposition. Time-dependent wind and turbulence fields are generated with a prognostic mesoscale numerical model and are used to advect and disperse individually released particles that are each assigned a mass. These particles are subjected to mass reduction in two ways depending on their physical location. Particles near the surface experience a decrease in mass using the concept of a dry deposition velocity, while the mass of particles located within areas of precipitation are depleted using a scavenging coefficient. Two levels of complexity are incorporated into the particle model. The simple case assumes constant values of dry deposition velocity and scavenging coefficient, while the more complex case varies the values according to meteorology, surface conditions, release material, and precipitation intensity. Instantaneous and cumulative dry and wet deposition are determined from the mass loss due to these physical mechanisms. A useful means of validating the model results is with data available from a recent accidental release of Cesium-137 from a steel-processing furnace in Algeciras, Spain in May, 1998. This paper describes the deposition modeling technique, as well as a comparison of simulated concentration and deposition with measurements taken for the Algeciras release.

  20. Quantifying atmospheric nitrogen deposition through a nationwide monitoring network across China

    NASA Astrophysics Data System (ADS)

    Xu, W.; Luo, X. S.; Pan, Y. P.; Zhang, L.; Tang, A. H.; Shen, J. L.; Zhang, Y.; Li, K. H.; Wu, Q. H.; Yang, D. W.; Zhang, Y. Y.; Xue, J.; Li, W. Q.; Li, Q. Q.; Tang, L.; Lu, S. H.; Liang, T.; Tong, Y. A.; Liu, P.; Zhang, Q.; Xiong, Z. Q.; Shi, X. J.; Wu, L. H.; Shi, W. Q.; Tian, K.; Zhong, X. H.; Shi, K.; Tang, Q. Y.; Zhang, L. J.; Huang, J. L.; He, C. E.; Kuang, F. H.; Zhu, B.; Liu, H.; Jin, X.; Xin, Y. J.; Shi, X. K.; Du, E. Z.; Dore, A. J.; Tang, S.; Collett, J. L., Jr.; Goulding, K.; Sun, Y. X.; Ren, J.; Zhang, F. S.; Liu, X. J.

    2015-11-01

    A Nationwide Nitrogen Deposition Monitoring Network (NNDMN) containing 43 monitoring sites was established in China to measure gaseous NH3, NO2, and HNO3 and particulate NH4+ and NO3- in air and/or precipitation from 2010 to 2014. Wet/bulk deposition fluxes of Nr species were collected by precipitation gauge method and measured by continuous-flow analyzer; dry deposition fluxes were estimated using airborne concentration measurements and inferential models. Our observations reveal large spatial variations of atmospheric Nr concentrations and dry and wet/bulk Nr deposition. On a national basis, the annual average concentrations (1.3-47.0 μg N m-3) and dry plus wet/bulk deposition fluxes (2.9-83.3 kg N ha-1 yr-1) of inorganic Nr species are ranked by land use as urban > rural > background sites and by regions as north China > southeast China > southwest China > northeast China > northwest China > Tibetan Plateau, reflecting the impact of anthropogenic Nr emission. Average dry and wet/bulk N deposition fluxes were 20.6 ± 11.2 (mean ± standard deviation) and 19.3 ± 9.2 kg N ha-1 yr-1 across China, with reduced N deposition dominating both dry and wet/bulk deposition. Our results suggest atmospheric dry N deposition is equally important to wet/bulk N deposition at the national scale. Therefore, both deposition forms should be included when considering the impacts of N deposition on environment and ecosystem health.

  1. Atmospheric deposition of sup 7 Be and sup 10 Be

    SciTech Connect

    Brown, L. ); Stensland, G.J. ); Klein, J.; Middleton, R. )

    1989-01-01

    Measurements of {sup 10}Be in precipitation taken in Hawaii, Illinois and New Jersey over a period of five years are reported. The problem of contamination by the isotope being resuspended on wind blown soil that is also collected is addressed. Rain collected at Mauna Loa, Hawaii has such low values of dust contamination that it has been taken as clean, and the data from Illinois and New Jersey are evaluated on that assumption. The conclusion is that the deposition in a given amount of rain for the non-resuspended component is the same for all three stations, and the authors propose that the annual rate for mid-latitude locations have moderate rainfall is proportional to the local rainfall. {sup 7}Be, which is probably negligibly contributed to the measurements by soil contamination was measured for individual rains in Illinois and found to have a deposition of 1.4 {times} 10{sup 4} atom/cm{sup 3}. The authors have found that concentration variations between precipitation events greater than a factor of 20 exist for both isotopes and that relatively rare, high concentration events dominate deposition, thereby requiring long periods of observation to avoid significant error. Based on their own and other data they conclude that the best value for {sup 10}Be deposition is 1.5 {times} 10{sup 4} atom/cm{sup 3}, uncertain by 20%, and for {sup 7}Be is 1.2 {times} 10{sup 4} atom/cm{sup 3}, uncertain by 25%. A global average deposition rate cannot be inferred directly for either isotope from these kinds of data; however, the theoretical global deposition rate for {sup 10}Be is shown to be consistent with the deposition reported here, if the concentration in equatorial rain is about 3300 atom/g.

  2. Atmospheric deposition of heavy metals (Cu, Zn, Cd and Pb) in Varanasi City, India.

    PubMed

    Sharma, Rajesh Kumar; Agrawal, Madhoolika; Marshall, Fiona M

    2008-07-01

    Rapid growth in urbanization and industrialization in developing countries may significantly contribute in heavy metal contamination of vegetables through atmospheric depositions. In the present study, an assessment was made to investigate the spatial and seasonal variations in deposition rates of heavy metals and its contribution to contamination of palak (Beta vulgaris). Samples of bulk atmospheric deposits and Beta vulgaris for analysis of Cu, Zn, Cd and Pb were collected from different sampling locations differing in traffic density and land use patterns. The results showed that the sampling locations situated in industrial or commercial areas with heavy traffic load showed significantly elevated levels of Cu, Zn and Cd deposition rate as compared to those situated in residential areas with low traffic load. The deposition rates of Cu, Zn and Cd were significantly higher in summer and winter as compared to rainy season, however, Pb deposition rate was significantly higher in rainy and summer seasons as compared to winter season. Atmospheric depositions have significantly elevated the levels of heavy metals in B. vulgaris collected during evening as compared to those collected in morning hours. The study further showed that local population has maximum exposure to Cd contamination through consumption of B. vulgaris. The present study clearly points out the urban and industrial activities of a city have potential to elevate the levels of heavy metals in the atmospheric deposits, which may consequently contaminate the food chain and thus posing health risk to the local population. PMID:17879134

  3. SPATIAL AND TEMPORAL TRENDS IN THE CHEMISTRY OF ATMOSPHERIC DEPOSITION IN NEW ENGLAND

    EPA Science Inventory

    The authors have evaluated atmospheric deposition related geochemical changes in New England and Quebec by means of (1) transect studies of soil chemistry parallel to pH and metal deposition gradients: and (2) chemical analysis of lake sediments with the following results: (a) Mn...

  4. Atmospheric Deposition of Heavy Metals in Soil Affected by Different Soil Uses of Southern Spain

    NASA Astrophysics Data System (ADS)

    Acosta, J. A.; Faz, A.; Martínez-Martínez, S.; Bech, J.

    2009-04-01

    Heavy metals are a natural constituent of rocks, sediments and soils. However, the heavy metal content of top soils is also dependent on other sources than weathering of the indigenous minerals; input from atmospheric deposition seems to be an important pathway. Atmospheric deposition is defined as the process by which atmospheric pollutants are transferred to terrestrial and aquatic surfaces and is commonly classified as either dry or wet. The interest in atmospheric deposition has increased over the past decade due to concerns about the effects of deposited materials on the environment. Dry deposition provides a significant mechanism for the removal of particles from the atmosphere and is an important pathway for the loading of heavy metals into the soil ecosystem. Within the last decade, an intensive effort has been made to determine the atmospheric heavy metal deposition in both urban and rural areas. The main objective of this study was to identification of atmospheric heavy metals deposition in soil affected by different soil uses. Study area is located in Murcia Province (southeast of Spain), in the surroundings of Murcia City. The climate is typically semiarid Mediterranean with an annual average temperature of 18°C and precipitation of 350 mm. In order to determine heavy metals atmospheric deposition a sampling at different depths (0-1 cm, 1-5 cm, 5-15 cm and 15-30 cm) was carried out in 7 sites including agricultural soils, two industrial areas and natural sites. The samples were taken to the laboratory where, dried, passed through a 2 mm sieve, and grinded. For the determination of the moisture the samples were weighed and oven dried at 105 °C for 24 h. The total amounts of metals (Pb, Cu, Pb, Zn, Cd, Mn, Ni and Cr) were determined by digesting the samples with nitric/perchoric acids and measuring with ICP-MS. Results showed that zinc contamination in some samples of industrial areas was detected, even this contamination reaches 30 cm depth; thus it is

  5. Quantifying atmospheric nitrogen deposition through a nationwide monitoring network across China

    NASA Astrophysics Data System (ADS)

    Xu, W.; Luo, X. S.; Pan, Y. P.; Zhang, L.; Tang, A. H.; Shen, J. L.; Zhang, Y.; Li, K. H.; Wu, Q. H.; Yang, D. W.; Zhang, Y. Y.; Xue, J.; Li, W. Q.; Li, Q. Q.; Tang, L.; Lu, S. H.; Liang, T.; Tong, Y. A.; Liu, P.; Zhang, Q.; Xiong, Z. Q.; Shi, X. J.; Wu, L. H.; Shi, W. Q.; Tian, K.; Zhong, X. H.; Shi, K.; Tang, Q. Y.; Zhang, L. J.; Huang, J. L.; He, C. E.; Kuang, F. H.; Zhu, B.; Liu, H.; Jin, X.; Xin, Y. J.; Shi, X. K.; Du, E. Z.; Dore, A. J.; Tang, S.; Collett, J. L., Jr.; Goulding, K.; Zhang, F. S.; Liu, X. J.

    2015-07-01

    Global reactive nitrogen (Nr) deposition to terrestrial ecosystems has increased dramatically since the industrial revolution. This is especially true in recent decades in China due to continuous economic growth. However, there are no comprehensive reports of both measured dry and wet Nr deposition across China. We therefore conducted a multiple-year study during the period mainly from 2010 to 2014 to monitor atmospheric concentrations of five major Nr species of gaseous NH3, NO2 and HNO3, and inorganic nitrogen (NH4+ and NO3-) in both particles and precipitation, based on a Nationwide Nitrogen Deposition Monitoring Network (NNDMN, covering 43 sites) in China. Wet deposition fluxes of Nr species were measured directly; dry deposition fluxes were estimated using airborne concentration measurements and inferential models. Our observations reveal large spatial variations of atmospheric Nr concentrations and dry and wet Nr deposition. The annual average concentrations (1.3-47.0 μg N m-3) and dry plus wet deposition fluxes (2.9-75.2 kg N ha-1 yr-1) of inorganic Nr species ranked by region as North China > Southeast China > Southwest China > Northeast China > Northwest China > the Tibetan Plateau or by land use as urban > rural > background sites, reflecting the impact of anthropogenic Nr emission. Average dry and wet N deposition fluxes were 18.5 and 19.3 kg N ha-1 yr-1, respectively, across China, with reduced N deposition dominating both dry and wet deposition. Our results suggest atmospheric dry N deposition is equally important to wet N deposition at the national scale and both deposition forms should be included when considering the impacts of N deposition on environment and ecosystem health.

  6. NATURAL MERCURY ISOTOPES AS TRACERS OF SOURCES, CYCLING, AND DEPOSITION OF ATMOSPHERIC MERCURY

    EPA Science Inventory

    This research centers on the use of mercury isotope systematics as a new way of investigating natural and anthropogenic emissions of mercury into the atmosphere and of the atmospheric processes that affect transportation and deposition. Given the fact that isotope systematics of ...

  7. Aerosol resuspension from fabric: implications for personal monitoring in the beryllium industry.

    PubMed

    Bohne, J E; Cohen, B S

    1985-02-01

    The fabric used for work clothing at an industrial site can significantly influence personal monitor (PM) exposure estimates because dust resuspension from clothing can increase the concentration at the sampler inlet. The magnitude of the effect depends on removal forces and on the interaction of the contaminant particles with work garments. Aerosol deposition and resuspension on cotton and Nomex aramid fabrics was evaluated at a beryllium refinery. Electrostatically charged cotton backdrops collected more beryllium than neutral controls, but electronegative Nomex backdrops did not. Moving fabrics collected more beryllium than did stationary controls. When contaminated fabrics were agitated, PMs mounted 2.5 cm in front of the fabric collected more beryllium than monitors above the fabric, positioned to simulate the nose or mouth. The difference between the air concentrations measured by these PMs increased with Be loading and tended to level off for highly contaminated fabric. Cotton resuspended a larger fraction of its contaminant load than Nomex. These results are consistent with current knowledge of the behavior of particles on fabric fibers. Aerosol resuspension from garments is an important consideration in assessing inhalation exposure to toxic dusts. A garment may attract and retain toxic particles. This contamination is then available for later resuspension. PMID:3976498

  8. Aerosol resuspension from fabric: implications for personal monitoring in the beryllium industry

    SciTech Connect

    Bohne, J.E. Jr.; Cohen, B.S.

    1985-02-01

    The fabric used for work clothing at an industrial site can significantly influence personal monitor (PM) exposure estimates because dust resuspension from clothing can increase the concentration at the sampler inlet. The magnitude of the effect depends on removal forces and on the interaction of the contaminant particles with work garments. Aerosol deposition and resuspension on cotton and Nomex aramid fabrics was evaluated at a beryllium refinery. Electrostatically charged cotton backdrops collected more beryllium than neutral controls, but electronegative Nomex backdrops did not. Moving fabrics collected more beryllium than did stationary controls. When contaminated fabrics were agitated, PMs mounted 2.5 cm in front of the fabric collected more beryllium than monitors above the fabric, positioned to simulate the nose or mouth. The difference between the air concentrations measured by these PMs increased with Be loading and tended to level off for highly contaminated fabric. Cotton resuspended a larger fraction of its contaminant load than Nomex. These results are consistent with current knowledge of the behavior of particles on fabric fibers. Aerosol resuspension from garments is an important consideration in assessing inhalation exposure to toxic dusts. A garment may attract and retain toxic particles. This contamination is then available for later resuspension.

  9. Impact of natural (waves and currents) and anthropogenic (trawl) resuspension on the export of particulate matter to the open ocean: Application to the Gulf of Lion (NW Mediterranean)

    NASA Astrophysics Data System (ADS)

    Ferré, B.; Durrieu de Madron, X.; Estournel, C.; Ulses, C.; Le Corre, G.

    2008-08-01

    Modern sediment deposits on continental margins form a vast reservoir of particulate matter that is regularly affected by resuspension processes. Resuspension by bottom trawling on shelves with strong fishing activity can modify the scale of natural disturbance by waves and currents. Recent field data show that the impact of bottom trawls on fine sediment resuspension per unit surface is comparable with that of the largest storms. We assessed the impact of both natural and anthropogenic processes on the dispersal of riverborne particles and shelf sediments on the Gulf of Lion shelf. We performed realistic numerical simulations of resuspension and transport forced by currents and waves or by a fleet of bottom trawlers. Simulations were conducted for a 16-month period (January 1998-April 1999) to characterise the seasonal variability. The sediment dynamics takes into account bed armoring, ripple geometry and the cohesive and non-cohesive characteristics of the sediments. Essential but uncertain parameters (clay content, erosion fluxes and critical shear stress for cohesive sediment) were set with existing data. Resuspension by waves and currents was controlled by shear stress, whereas resuspension by trawls was controlled by density and distribution of the bottom trawler fleet. Natural resuspension by waves and currents mostly occurred during short seasonal episodes, and was concentrated on the inner shelf. Trawling-induced resuspension, in contrast, occurred regularly throughout the year and was concentrated on the outer shelf. The total annual erosion by trawls (5.6×10 6 t y -1, t for metric tonnes) was four orders of magnitude lower than the erosion induced by waves and currents (35.3×10 9 t y -1). However the net resuspension (erosion/deposition budget) for trawling (0.4×10 6 t y -1) was only one order of magnitude lower than that for waves and currents (9.2×10 6 t y -1). Off-shelf export concerned the finest fraction of the sediment (clays and fine silts

  10. POLLUTANT SAMPLER FOR MEASUREMENTS OF ATMOSPHERIC ACIDIC DRY DEPOSITION

    EPA Science Inventory

    An acidic pollutant sampler for dry deposition monitoring has been designed and evaluated in laboratory and field studies. The system, which is modular and simple to operate, samples gaseous HNO3, NH3, SO2 and NO2 and particulate SO4(-2), NO3(1-) and NH4(1+) and is made of Teflon...

  11. Acid deposition: Atmospheric processes in Eastern North America

    SciTech Connect

    Not Available

    1983-01-01

    This report examines scientific evidence on the relationship between emissions of acid-forming pollutants and damage to sensitive ecosystems from acid rain and other forms of acid deposition. The report's conclusions represent the most authoritative statement yet that reductions in emissions of these pollutants will result in proportional reductions in acid rain.

  12. Short-term variability of mineral dust, metals and carbon emission from road dust resuspension

    NASA Astrophysics Data System (ADS)

    Amato, Fulvio; Schaap, Martijn; Denier van der Gon, Hugo A. C.; Pandolfi, Marco; Alastuey, Andrés; Keuken, Menno; Querol, Xavier

    2013-08-01

    Particulate matter (PM) pollution in cities has severe impact on morbidity and mortality of their population. In these cities, road dust resuspension contributes largely to PM and airborne heavy metals concentrations. However, the short-term variation of emission through resuspension is not well described in the air quality models, hampering a reliable description of air pollution and related health effects. In this study we experimentally show that the emission strength of resuspension varies widely among road dust components/sources. Our results offer the first experimental evidence of different emission rates for mineral dust, heavy metals and carbon fractions due to traffic-induced resuspension. Also, the same component (or source) recovers differently in a road in Barcelona (Spain) and a road in Utrecht (The Netherlands). This finding has important implications on atmospheric pollution modelling, mostly for mineral dust, heavy metals and carbon species. After rain events, recoveries were generally faster in Barcelona rather than in Utrecht. The largest difference was found for the mineral dust (Al, Si, Ca). Tyre wear particles (organic carbon and zinc) recovered faster than other road dust particles in both cities. The source apportionment of road dust mass provides useful information for air quality management.

  13. 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.

  14. ATMOSPHERIC DEPOSITION TO MOUNTAIN FOREST SYSTEMS: WORKSHOP PROCEEDINGS APRIL 1984

    EPA Science Inventory

    The Atmospheric Sciences Research Center of the State University of New York-Albany organized and hosted a workshop which specifically addressed the need, design and implementation of research, development and monitoring with advanced techniques for these purposes: (a) to identif...

  15. NATIONAL ATMOSPHERIC DEPOSITION PROGRAM (NADP), 4 NC SITES

    EPA Science Inventory

    National Atmospheric Depostion Program (NADP) data for 4 sites in North Carolina - those within or in close proximity to the Albemarle-Pamlico Estuary watershed. No Virginia sites are within this watershed. See included text files for file contents. Separate directories for each ...

  16. Contamination of surface-water bodies after reactor accidents by the erosion of atmospherically deposited radionuclides.

    PubMed

    Helton, J C; Muller, A B; Bayer, A

    1985-06-01

    Reactor safety analyses usually do not consider the population risk which might result from the contamination of surface-water bodies after reactor accidents by the erosion of atmospherically deposited radionuclides. This paper is intended to provide perspective on the reasonableness of this omission. Data are presented which are suggestive of the rates at which atmospherically deposited radionuclides might erode into surface-water bodies. These rates are used in the calculation of potential health effects resulting from surface-water contamination due to such erosion. These health effects are compared with predicted health effects due to atmospheric and terrestrial pathways after reactor accidents. The presented results support the belief that the contamination of surface-water bodies after reactor accidents by the erosion of atmospherically deposited radionuclides is not a major contributor to the risk associated with such accidents. PMID:3997527

  17. Potential geographic distribution of atmospheric nitrogen deposition from intensive livestock production in North Carolina, USA.

    PubMed

    Costanza, Jennifer K; Marcinko, Sarah E; Goewert, Ann E; Mitchell, Charles E

    2008-07-15

    To examine the consequences of increased spatial aggregation of livestock production facilities, we estimated the annual production of nitrogen in livestock waste in North Carolina, USA, and analyzed the potential distribution of atmospheric nitrogen deposition from confined animal feeding operations ("CAFO") lagoons. North Carolina is a national center for industrial livestock production. Livestock is increasingly being raised in CAFOs, where waste is frequently held, essentially untreated, in open-air lagoons. Reduced nitrogen in lagoons is volatilized as ammonia (NH(3)), transported atmospherically, and deposited to other ecosystems. The Albemarle-Pamlico Sound, NC, is representative of nitrogen-sensitive coastal waters, and is a major component of the second largest estuarine complex in the U.S. We used GIS to model the area of water in the Sound within deposition range of CAFOs. We also evaluated the number of lagoons within deposition range of each 1 km(2) grid cell of the state. We considered multiple scenarios of atmospheric transport by varying distance and directionality. Modeled nitrogen deposition rates were particularly elevated for the Coastal Plain. This pattern matches empirical data, suggesting that observed regional patterns of reduced nitrogen deposition can be largely explained by two factors: limited atmospheric transport distance, and spatial aggregation of CAFOs. Under our medium-distance scenario, a small portion (roughly 22%) of livestock production facilities contributes disproportionately to atmospheric deposition of nitrogen to the Albemarle-Pamlico Sound. Furthermore, we estimated that between 14-37% of the state receives 50% of the state's atmospheric nitrogen deposition from CAFO lagoons. The estimated total emission from livestock is 134,000 t NH(3) yr(-1), 73% of which originates from the Coastal Plain. Stronger waste management and emission standards for CAFOs, particularly those on the Coastal Plain nearest to sensitive water

  18. 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.

  19. Empirical critical loads of atmospheric nitrogen deposition for nutrient enrichment and acidification of sensitive US lakes

    NASA Astrophysics Data System (ADS)

    Baron, J.; Driscoll, C. T.; Stoddard, J. L.; Richer, E. E.

    2011-12-01

    Ecological effects of elevated atmospheric N deposition for high elevation lakes of the western and northeastern US include nutrient enrichment and acidification. These effects are most evident in high elevation lakes, which are sensitive to atmospheric deposition and have been minimally impacted by land disturbance. Nitrogen-limited lakes will exhibit increases in productivity and shifts in the composition of phytoplankton in response to increases in atmospheric N deposition. Wet N deposition reported by NADP/NTN does not accurately depict total N deposition including dry species, and national NADP maps can misrepresent total deposition amounts in regions of complex terrain, so we calculated N deposition three different ways in order to explore critical loads. The nutrient enrichment critical load for Western lakes ranged 1.0-3.0 kg N per ha per yr, reflecting near-lack of watershed vegetation in complex, snow-melt dominated terrain. The nutrient enrichment critical load for Northeastern lakes ranged 3.5-6.0 kg N per ha per yr. The N acidification critical loads associated with episodic N pulses in waters with low values of acid neutralizing capacity were 4.0 kg N per ha per yr (western) and 8.0 kg N per ha per yr (northeastern). Empirical critical loads for N-caused acidification were difficult to determine due to lack of observations in the West, and because of the additive effects of decades of atmospheric sulfur deposition in the Northeast. For both nutrient enrichment and acidification, the N critical load was a function of how atmospheric N deposition was determined.

  20. Impact of atmospheric nitrogen deposition on phytoplankton productivity in the South China Sea

    NASA Astrophysics Data System (ADS)

    Kim, Tae-Wook; Lee, Kitack; Duce, Robert; Liss, Peter

    2014-05-01

    The impacts of anthropogenic nitrogen (N) deposition on the marine N cycle are only now being revealed, but the magnitudes of those impacts are largely unknown in time and space. The South China Sea (SCS) is particularly subject to high anthropogenic N deposition, because the adjacent countries are highly populated and have rapidly growing economies. Analysis of data sets for atmospheric N deposition, satellite chlorophyll-a (Chl-a), and air mass back trajectories reveals that the transport of N originating from the populated east coasts of China and Indonesia, and its deposition to the ocean, has been responsible for the enhancements of Chl-a in the SCS. We found that atmospheric N deposition contributed approximately 20% of the annual biological new production in the SCS. The airborne contribution of N to new production in the SCS is expected to grow considerably in the coming decades.

  1. Atmospheric inorganic nitrogen deposition to a typical red soil forestland in southeastern China.

    PubMed

    Fan, Jian-Ling; Hu, Zheng-Yi; Wang, Ti-Jian; Zhou, Jing; Wu, Cong-Yang-Hui; Xia, Xu

    2009-12-01

    A 2-year monitoring study was conducted to estimate nitrogen deposition to a typical red soil forestland in southeastern China. The dry deposition velocities (V(d)) were estimated using big leaf resistance analogy model. Atmospheric nitrogen dry deposition was estimated by combing V(d) and nitrogen compounds concentrations, and the wet deposition was calculated via rainfall and nitrogen concentrations in rainwater. The total inorganic nitrogen deposition was 83.7 kg ha(-1) a(-1) in 2004 and 81.3 kg ha(-1) a(-1) in 2005, respectively. The dry deposition contributed 78.6% to total nitrogen deposition, in which ammonia was the predominant contributor that accounted for 86.1%. Reduced nitrogen compounds were the predominant contributors, accounting for 78.3% of total nitrogen deposition. The results suggested that atmospheric inorganic nitrogen could be attributed to intensive agricultural practices such as excessive nitrogen fertilization and livestock production. Therefore, impacts of atmospheric nitrogen originated from agriculture practices on nearby forest ecosystems should be evaluated. PMID:18998222

  2. Modelling the resuspension of volcanic ash from the Valley of Ten Thousand Smokes

    NASA Astrophysics Data System (ADS)

    Schwaiger, H. F.; Wallace, K.

    2015-12-01

    The 1912 eruption of Novarupta-Katmai was the world's most voluminous eruption since the 1815 eruption of Tombora. The eruption produced 17 km3 of ashfall and 11 km3 of pyroclastic flow deposits that filled nearby valleys, creating what is today known as the Valley of Ten Thousand Smokes. These voluminous pyroclastic deposits continue to pose hazards when strong winds in the valley resuspend ash in times of low snow cover. These resuspension events may be confined to the valley and only recorded when there are local observations (web camera images, field crew). Occasionally, however, these events can loft ash up to altitudes of several kilometers and extend up to 250 km downwind, where it becomes an aviation hazard. A compilation of satellite observations and pilot reports indicate that such significant events occurred on at least 19 occasions since 2003. The longest duration events occurred in the autumn months of September and October. Predicting the resuspension of ash requires estimates of when the ash is exposed (low snow cover), the magnitude of surface wind gusts, and the threshold friction velocity (u*). Models of u* require a characterization of the source ash (density, grain-size distribution) as well as soil moisture. We have sampled source deposits and have installed instruments in the Katmai region to record the relevant meteorological parameters in order to better predict these resuspension events. Using real-time measurements coupled with high-resolution (6 km, 1 hour) meteorological forecast products and a reanalysis of conditions that produced historic events, we constrain the parameters applicable the resuspension of Novarupta ash thus improving our ability to forecast this potential ash hazard. The volcanic ash dispersion and deposition model, Ash3d, will be used to forecast the transport of the resuspended ash.

  3. Nighttime auroral energy deposition in the middle atmosphere

    NASA Technical Reports Server (NTRS)

    Goldberg, R. A.; Jackman, C. H.; Barcus, J. R.; Soraas, F.

    1984-01-01

    Ionospheric rocket sounding data for eight nighttime auroral events are used to characterize relativistic electron showers and their effects on atmospheric ozone. The rockets were launched from the Poker Flat Research Range in Alaska and from Andoya, Norway over the period 1976-82. Energetic fluxes were always detected but were of insufficient magnitude to produce significant changes in stratospheric ozone. However, middle atmospheric energy sources were found to be dominated by relativistic electrons and X-ray bremmstrahlung, the latter from 40-55 km and the former from 55-60 km altitudes. The ionizing radiation is concluded to be a significant factor in mesospheric ion conductivity, mobility, electric field structure and analytical models for the ion-neutral chemistry.

  4. 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

  5. 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

  6. 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. PMID:24977238

  7. Human - driven atmospheric deposition of N & P controls on the East Mediterranean marine ecosystem

    NASA Astrophysics Data System (ADS)

    Christodoulaki, Sylvia; Petihakis, George; Mihalopoulos, Nikolaos; Tsiaras, Konstantinos; Triantafyllou, George; Kanakidou, Maria

    2016-04-01

    The historical and future impacts of atmospheric deposition of inorganic nitrogen (N) and phosphorus (P) on the marine ecosystem in the East Mediterranean Sea are investigated by using a 1-D coupled physical- biogeochemical model, set-up for the Cretan Sea as a representative area of the basin. For the present-day simulation (2010), the model is forced by observations of atmospheric deposition fluxes at Crete, while for the hindcast (1860) and forecast (2030) simulations, the changes in atmospheric deposition calculated by global chemistry- transport models are applied to the present-day observed fluxes. The impact of the atmospheric deposition on the fluxes of carbon in the food chain is calculated together with the contribution of human activities to these impacts. The results show that total phytoplanktonic biomass increased by 16% over the past 1.5 century. Small fractional changes in carbon fluxes and planktonic biomasses are predicted for the near future. Simulations show that atmospheric deposition of N and P may be the main mechanism responsible for the anomalous N to P ratio observed in the Mediterranean Sea.

  8. Global Simulation of Atmospheric Mercury Concentrations and Deposition Fluxes. Appendix Q

    NASA Technical Reports Server (NTRS)

    Shia, Run-Lie; Seigneur, Christian; Pai, Prasad; Ko, Malcolm; Sze, Nien Dak

    1999-01-01

    Results from a numerical model of the global emissions, transport, chemistry, and deposition of mercury (Hg) in the atmosphere are presented. Hg (in the form of Hg(O) and Hg(II)) is emitted into the atmosphere from natural and anthropogenic sources (estimated to be 4000 and 2100 Mg/ yr, respectively). It is distributed between gaseous, aqueous and particulate phases. Removal of Hg from the atmosphere occurs via dry deposition and wet deposition, which are calculated by the model to be 3300 and 2800 Mg/ yr, respectively. Deposition on land surfaces accounts for 47% of total global deposition. The simulated Hg ambient surface concentrations and deposition fluxes to the Earth's surface are consistent with available observations. Observed spatial and seasonal trends are reproduced by the model, although larger spatial variations are observed in Hg(O) surface concentrations than are predicted by the model. The calculated atmospheric residence time of Hg is -1.7 years. Chemical transformations between Hg(O) and HG(II) have a strong influence on Hg deposition patterns because HG(II) is removed faster than Hg(O). Oxidation of Hg(O) to HG(II) occurs primarily in the gas phase, whereas HG(II) reduction to Hg(O) occurs solely in the aqueous phase. Our model results indicated that in the absence of the aqueous reactions the atmospheric residence time of Hg is reduced to 1.2 from 1.7 years and the Hg surface concentration is -25% lower because of the absence of the HG(II) reduction pathway. This result suggests that aqueous chemistry is an essential component of the atmospheric cycling of Hg.

  9. Spatial and seasonal atmospheric PAH deposition patterns and sources in Rhode Island

    NASA Astrophysics Data System (ADS)

    Schifman, Laura A.; Boving, Thomas B.

    2015-11-01

    Polycyclic aromatic hydrocarbons (PAH) enter the environment through various combustion processes and can travel long distances via atmospheric transport. Here, atmospheric PAH deposition was measured in six locations throughout Rhode Island using passive atmospheric bulk-deposition samplers for three years. The measurements were evaluated using two source-specific PAH isomer signatures, a multivariate receptor model, and an innovative contamination index that is weighted based on PAH contamination, number of detected compounds, and toxicity. Urban areas had significantly higher deposition rates (up to 2261 μg m-2 yr-1 ∑PAH) compared to peri-urban, coastal, and rural areas (as low as 73.6 μg m-2 yr-1 ∑PAH). In fall and winter, PAH deposition was up to 10 times higher compared to summer/spring. On an annual basis a total of 3.64 t yr-1 ∑PAH (2256.9 μg yr-1 m-2 ∑PAH) are estimated to be deposited atmospherically onto Rhode Island. Both, the analysis using isomer ratios and the statistical analysis using positive matrix factorization agreed on source identification. Overall gasoline, petrodiesel, and oil combustion sources were identified in all samples year-round while wood combustion associated PAH deposition was only detected during the cold season.

  10. Comparative assessment of regionalisation methods of monitored atmospheric deposition loads

    NASA Astrophysics Data System (ADS)

    Reinstorf, Frido; Binder, Maja; Schirmer, Mario; Grimm-Strele, Jost; Walther, Wolfgang

    The objective of this investigation is to assess the suitability of well-known regionalisation methods of data from existing deposition monitoring networks for use in water resources management. For this purpose a comparison of the applicability and accuracy of various regionalisation methods was made. A crucial point is the data demand of the various methods. In this investigation the deterministic and geostatistical methods inverse distance weighting (IDW), ordinary kriging (OK) and external drift kriging (EDK) as well as the chemical transport models METRAS-MUSCAT, EMEP, EDACS and EUTREND have been characterised and evaluated. The methods IDW and OK have been applied to the investigation areas—the German Federal States of Lower Saxony and Saxony. An evaluation of these methods was carried out with a cross-validation procedure. The result was in most cases a higher accuracy for the OK method. The EDK method has been investigated in order to find suitable drift variables from the parameters precipitation amount, altitude and wind direction. With help of a correlation analysis a suitable drift variable could not be found. After the application of OK, verification was carried out by a comparison of the estimated data set with an independently determined data set. The result was a relatively smaller deviation of the estimated data set. The investigation considers data from routine monitoring networks as well as networks for special applications and has been carried out on the basis of monitoring networks of the two states. The investigated database was wet and bulk deposition of the substances NH 4+, SO 42-, NO 3-, Na +, Pb 2+, and Cd 2+ in Lower Saxony and SO 42- in Saxony. From this, a consistent database of bulk deposition data was built. From all applied methods OK proved to cope best with the data deficiencies that were found.

  11. Sources of nitrogen in three watersheds of northern Florida, USA: Mainly atmospheric deposition

    SciTech Connect

    Fu, Ji-Meng; Winchester, J.W. )

    1994-03-01

    Atmospheric deposition is estimated to be the principal source of N in water that flows to the Apalachicola river from the Chattahoochee and Flint Rivers (ACF) as well as in two nearby small rivers, Ochlockonee (Och) and Sopchoppy (Sop), that drain watersheds with different land use characteristics. By mass balance and descriptive statistics of hundreds of rainfall and river water samples from monitoring programs since the 1960s, the average nitrate and ammonium deposition flux from the atmosphere is sufficient to account for N that flows toward Apalachicola Bay, an estuary in which N may be a limiting nutrient. Urban and agricultural sources of N in the three watersheds ACF, Och, and Sop appear to be relatively smaller. The work was based on long-term data bases from the National Atmospheric Deposition Program (NADP) rain chemistry monitoring network and the U.S. Geological Survey (USGS) water monitoring program. Average atmospheric N depositions to the three river watersheds are nearly the same as river fluxes of N in all forms monitored. Nitrogen is not likely to be a limiting nutrient in the three watersheds, since river water N:P exceeds the Redfield ratio. An estimate of largest possible input of urban sewage is several times lower than the atmospheric flux of N to the ACF watershed. And N from N-fertilizer, comparable to the atmospheric deposition flux of N, is likely to be smaller if mostly retained in crops or farmland before it reaches the estuary. Annual nitrogen export from the Apalachicola River to the estuary, 1.22 x 10[sup 9] moles N yr[sup [minus]1], consists of organic nitrogen 60%, nitrate 34%, and NH[sup +][sub 4]6%. Atmospheric nitrate and sulfate depositions are highly correlated, both being principally from fossil fuel combustion. Hydrologic conditions, which exhibit variations on seasonal and longer time scales, play an important role in the transport of nutrients and other species in the rivers.

  12. Sources of nitrogen in three watersheds of northern Florida, USA: Mainly atmospheric deposition

    NASA Astrophysics Data System (ADS)

    Fu, Ji-Meng; Winchester, John W.

    1994-03-01

    Atmospheric deposition is estimated to be the principal source of N in water that flows to the Apalachicola River from the Chattahoochee and Flint Rivers (ACF) as well as in two nearby small rivers, Ochlockonee (Och) and Sopchoppy (Sop), that drain watersheds with different land use characteristics. By mass balance and descriptive statistics of hundreds of rainfall and river water samples from monitoring programs since the 1960s, the average nitrate and ammonium deposition flux from the atmosphere is sufficient to account for N that flows toward Apalachicola Bay, an estuary in which N may be a limiting nutrient. Urban and agricultural sources of N in the three watersheds ACF, Och and Sop appear to be relatively smaller. The work was based on long-term data bases from the National Atmospheric Deposition Program (NADP) rain chemistry monitoring network and the U.S. Geological Survey (USGS) water monitoring program. Average atmospheric N depositions to the three river watersheds are nearly the same as river fluxes of N in all forms monitored. Nitrogen is not likely to be a limiting nutrient in the three watersheds, since river water N:P exceeds the Redfield ratio. An estimate of largest possible input of urban sewage is several times lower than the atmospheric flux of N to the ACF watershed. And N from N-fertilizer, comparable to the atmospheric deposition flux of N, is likely to be smaller if mostly retained in crops or farmland before it reaches the estuary. Annual nitrogen export from the Apalachicola River to the estuary, 1.22 × 10 9 moles N yr -1, consists of organic nitrogen 60%, nitrate 34% and NH 4+ 6%. Atmospheric nitrate and sulfate depositions are highly correlated, both being principally from fossil fuel combustion. Hydrologie conditions, which exhibit variations on seasonal and longer time scales, play an important role in the transport of nutrients and other species in the rivers.

  13. Distribution of atmospheric marine salt depositions over Continental Western Europe.

    PubMed

    Delalieux, F; van Grieken, R; Potgieter, J H

    2006-06-01

    This contribution describes the distribution of marine salt aerosols in Belgium, France and Spain, as obtained from applying a kriging model to a set of data. The data was collected over a period of nine years and included wet as well as dry deposition results. It was found that the concentration of the salt particles decreased the fastest in Spain and the slowest in Belgium with increasing inland distance from the sea. These findings have implications for the degradation of monuments and historical buildings as a result of salt attack and ingress that often accompany degradation due to air pollution. PMID:16772114

  14. Natural or anthropogenic? On the origin of atmospheric sulfate deposition in the Andes of southeastern Ecuador

    NASA Astrophysics Data System (ADS)

    Makowski Giannoni, S.; Rollenbeck, R.; Trachte, K.; Bendix, J.

    2014-05-01

    Atmospheric sulfur deposition above certain limits can represent a threat to tropical forests, causing nutrient imbalances and mobilizing toxic elements that impact biodiversity and forest productivity. Atmospheric sources of sulfur deposited by precipitation have being roughly identified in only a few lowland tropical forests. Even scarcer are these type of studies in tropical mountain forests, many of them megadiversity hotspots and especially vulnerable to acidic deposition. Here, the topographic complexity and related streamflow condition the origin, type, and intensity of deposition. Furthermore, in regions with a variety of natural and anthropogenic sulfur sources, like active volcanoes and biomass-burning, no source-emission data has been used for determining the contribution of each of them to the deposition. The main goal of the current study is to evaluate sulfate (SO4-) deposition by rain and occult precipitation at two topographic locations in a tropical mountain forest of southern Ecuador, and to trace back the deposition to possible emission sources applying back trajectory modeling. To link upwind natural (volcanic) and anthropogenic (urban/industrial and biomass-burning) sulfur emissions and observed sulfate deposition, we employed state of the art inventory and satellite data, including volcanic passive degassing as well. We conclude that biomass-burning sources generally dominate sulfate deposition at the evaluated sites. Minor sulfate transport occurs during the shifting of the predominant winds to the north and west. Occult precipitation sulfate deposition and likely rain sulfate deposition are mainly linked to biomass-burning emissions from the Amazon lowlands. Volcanic and anthropogenic emissions from the north and west contribute to occult precipitation sulfate deposition at the mountain crest Cerro del Consuelo meteorological station and to rain-deposited sulfate at the upriver mountain-pass El Tiro meteorological station.

  15. Natural or anthropogenic? On the origin of atmospheric sulfate deposition in the Andes of southeastern Ecuador

    NASA Astrophysics Data System (ADS)

    Makowski Giannoni, S.; Rollenbeck, R.; Trachte, K.; Bendix, J.

    2014-10-01

    Atmospheric sulfur deposition above certain limits can represent a threat to tropical forests, causing nutrient imbalances and mobilizing toxic elements that impact biodiversity and forest productivity. Atmospheric sources of sulfur deposited by precipitation have been roughly identified in only a few lowland tropical forests. Even scarcer are studies of this type in tropical mountain forests, many of them mega-diversity hotspots and especially vulnerable to acidic deposition. In these places, the topographic complexity and related streamflow conditions affect the origin, type, and intensity of deposition. Furthermore, in regions with a variety of natural and anthropogenic sulfur sources, like active volcanoes and biomass burning, no source emission data has been used for determining the contribution of each source to the deposition. The main goal of the current study is to evaluate sulfate (SO4- deposition by rain and occult precipitation at two topographic locations in a tropical mountain forest of southern Ecuador, and to trace back the deposition to possible emission sources applying back-trajectory modeling. To link upwind natural (volcanic) and anthropogenic (urban/industrial and biomass-burning) sulfur emissions and observed sulfate deposition, we employed state-of-the-art inventory and satellite data, including volcanic passive degassing as well. We conclude that biomass-burning sources generally dominate sulfate deposition at the evaluated sites. Minor sulfate transport occurs during the shifting of the predominant winds to the north and west. Occult precipitation sulfate deposition and likely rain sulfate deposition are mainly linked to biomass-burning emissions from the Amazon lowlands. Volcanic and anthropogenic emissions from the north and west contribute to occult precipitation sulfate deposition at the mountain crest Cerro del Consuelo meteorological station and to rain-deposited sulfate at the upriver mountain pass El Tiro meteorological station.

  16. Solar Flux Deposition And Heating Rates In Jupiter's Atmosphere

    NASA Astrophysics Data System (ADS)

    Perez-Hoyos, Santiago; Sánchez-Lavega, A.

    2009-09-01

    We discuss here the solar downward net flux in the 0.25 - 2.5 µm range in the atmosphere of Jupiter and the associated heating rates under a number of vertical cloud structure scenarios focusing in the effect of clouds and hazes. Our numerical model is based in the doubling-adding technique to solve the radiative transfer equation and it includes gas absorption by CH4, NH3 and H2, in addition to Rayleigh scattering by a mixture of H2 plus He. Four paradigmatic Jovian regions have been considered (hot-spots, belts, zones and Polar Regions). The hot-spots are the most transparent regions with downward net fluxes of 2.5±0.5 Wm-2 at the 6 bar level. The maximum solar heating is 0.04±0.01 K/day and occurs above 1 bar. Belts and zones characterization result in a maximum net downward flux of 0.5 Wm-2 at 2 bar and 0.015 Wm-2 at 6 bar. Heating is concentrated in the stratospheric and tropospheric hazes. Finally, Polar Regions are also explored and the results point to a considerable stratospheric heating of 0.04±0.02 K/day. In all, these calculations suggest that the role of the direct solar forcing in the Jovian atmospheric dynamics is limited to the upper 1 - 2 bar of the atmosphere except in the hot-spot areas. Acknowledgments: This work has been funded by Spanish MEC AYA2006-07735 with FEDER support and Grupos Gobierno Vasco IT-464-07.

  17. Assessing New Dry Deposition Parameterization Schemes for Incorporation into Global Atmospheric Transport Models

    NASA Astrophysics Data System (ADS)

    Khan, T.; Perlinger, J. A.; Wu, S.; Fairall, C. W.

    2014-12-01

    Dry deposition is a key process in atmosphere-surface exchange and is an important transmission route for atmospheric gases and aerosols to enter terrestrial and aquatic ecosystems. Vertical transport of atmospheric aerosols to Earth's surface is governed by several processes including turbulent transfer, interception, inertial impaction, settling, diffusion, turbophoresis, thermophoresis, and electrostatic effects. In global transport models (GTMs), particle dry deposition velocity (vd) from the lowest model layer to the surface is often parameterized using an electrical resistance analogy. This resistance analogy is widely used in a modified form to compute vd for steady-state dry deposition flux. Recently, a mass conservative formulation of dry deposition applicable to smooth and rough surfaces was proposed. Here, we evaluate dry deposition velocities computed using five different schemes with measurement results from a variety of surfaces including bare soil, grass, and coniferous, broad-leaf, and deciduous forest canopies. Based on this assessment, we provide suggestions for optimal treatment of dry deposition processes in GTMs and evaluate implementation of new dry deposition schemes.

  18. Atmospheric Mercury Transfer to Peat Bogs Dominated by Gaseous Elemental Mercury Dry Deposition.

    PubMed

    Enrico, Maxime; Roux, Gaël Le; Marusczak, Nicolas; Heimbürger, Lars-Eric; Claustres, Adrien; Fu, Xuewu; Sun, Ruoyu; Sonke, Jeroen E

    2016-03-01

    Gaseous elemental mercury (GEM) is the dominant form of mercury in the atmosphere. Its conversion into oxidized gaseous and particulate forms is thought to drive atmospheric mercury wet deposition to terrestrial and aquatic ecosystems, where it can be subsequently transformed into toxic methylmercury. The contribution of mercury dry deposition is however largely unconstrained. Here we examine mercury mass balance and mercury stable isotope composition in a peat bog ecosystem. We find that isotope signatures of living sphagnum moss (Δ(199)Hg = -0.11 ± 0.09‰, Δ(200)Hg = 0.03 ± 0.02‰, 1σ) and recently accumulated peat (Δ(199)Hg = -0.22 ± 0.06‰, Δ(200)Hg = 0.00 ± 0.04‰, 1σ) are characteristic of GEM (Δ(199)Hg = -0.17 ± 0.07‰, Δ(200)Hg = -0.05 ± 0.02‰, 1σ), and differs from wet deposition (Δ(199)Hg = 0.73 ± 0.15‰, Δ(200)Hg = 0.21 ± 0.04‰, 1σ). Sphagnum covered during three years by transparent and opaque surfaces, which eliminate wet deposition, continue to accumulate Hg. Sphagnum Hg isotope signatures indicate accumulation to take place by GEM dry deposition, and indicate little photochemical re-emission. We estimate that atmospheric mercury deposition to the peat bog surface is dominated by GEM dry deposition (79%) rather than wet deposition (21%). Consequently, peat deposits are potential records of past atmospheric GEM concentrations and isotopic composition. PMID:26849121

  19. Tracing atmospheric nitrate deposition in a complex semiarid ecosystem using delta17O.

    PubMed

    Michalski, Greg; Meixner, Thomas; Fenn, Mark; Hernandez, Larry; Sirulnik, Abby; Allen, Edith; Thiemens, Mark

    2004-04-01

    The isotopic composition of nitrate collected from aerosols, fog, and precipitation was measured and found to have a large 17O anomaly with delta17O values ranging from 20 percent per thousand to 30% percent per thousand (delta17O = delta17O - 0.52(delta18O)). This 17O anomaly was used to trace atmospheric deposition of nitrate to a semiarid ecosystem in southern California. We demonstrate that the delta17O signal is a conserved tracer of atmospheric nitrate deposition and is a more robust indicator of N deposition relative to standard delta18O techniques. The data indicate that a substantial portion of nitrate found in the local soil, stream, and groundwater is of atmospheric origin and does not undergo biologic processing before being exported from the system. PMID:15112822

  20. Environmental consequences of uranium atmospheric releases from fuel cycle facility: II. The atmospheric deposition of uranium and thorium on plants.

    PubMed

    Pourcelot, L; Masson, O; Renaud, P; Cagnat, X; Boulet, B; Cariou, N; De Vismes-Ott, A

    2015-03-01

    Uranium and thorium isotopes were measured in cypress leaves, wheat grains and lettuce taken in the surroundings of the uranium conversion facility of Malvési (South of France). The comparison of activity levels and activity ratios (namely (238)U/(232)Th and (230)Th/(232)Th) in plants with those in aerosols taken at this site and plants taken far from it shows that aerosols emitted by the nuclear site (uranium releases in the atmosphere by stacks and (230)Th-rich particles emitted from artificial ponds collecting radioactive waste mud) accounts for the high activities recorded in the plant samples close to the site. The atmospheric deposition process onto the plants appears to be the dominant process in plant contamination. Dry deposition velocities of airborne uranium and thorium were measured as 4.6 × 10(-3) and 5.0 × 10(-3) m s(-1), respectively. PMID:25500060

  1. Estimation of mercury loadings to Lake Ontario: Results from the Lake Ontario atmospheric deposition study (LOADS)

    NASA Astrophysics Data System (ADS)

    Lai, Soon-Onn; Holsen, Thomas M.; Han, Young-Ji; Hopke, Philip P.; Yi, Seung-Muk; Blanchard, Pierrette; Pagano, James J.; Milligan, Michael

    Atmospheric mercury (Hg) loadings to Lake Ontario were estimated using data measured at two land-based sites: Sterling, NY and Point Petre, Ont., as part of the Lake Ontario air deposition study (LOADS) between April 2002 and March 2003. These loadings were compared with those estimated using intensive data measured onboard the R/V Lake Guardian in April 2002, September 2002, and July 2003 (each approximately one week). Measured concentrations and modeled mass transfer coefficients of elemental mercury (Hg 0), reactive gaseous mercury (RGM) and particulate mercury (Hg (p)) in air and total Hg in precipitation were incorporated into a total deposition model including wet deposition, air-water gas exchange and particle dry deposition. Urban/rural Hg concentration ratios were assumed based on literature values. Assuming that 10% of the lake was influenced by urban areas, the annual net Hg atmospheric loadings of wet deposition, net air-water gas exchange of Hg 0 (deposition=300 kg yr -1 and emission=410 kg yr -1) and RGM, and Hg (p) dry deposition to Lake Ontario were estimated to be 170, -110, 68, and 20 kg, respectively, resulting in a net loading of 150 kg yr -1. Net Hg loadings were largest in the fall (46 kg) and smallest in the summer (20 kg). Hg 0, wet, RGM and Hg (p) deposition contributed 55%, 30%, 12%, and 3.6% of the total Hg deposition, respectively. The net loading was found to be most sensitive to the assumed urban/rural concentration ratios, wind speed, DGM concentration and Hg 0 transfer velocity. An increase in the influence of urban areas from 0% to 30% resulted in a 90% increase in the total loading demonstrating the complexity and non-linearity of the atmospheric deposition of mercury to Lake Ontario and the importance of quantifying the urban footprint.

  2. Characteristics of atmospheric depositions of ionic and carbonaceous components at remote sites in Japan

    NASA Astrophysics Data System (ADS)

    Sato, K.; Inomata, Y.; Kajino, M.; Tang, N.; Hayakawa, K.; Hakamata, M.; Morisaki, H.

    2015-12-01

    Atmospheric deposition process is important to evaluate lifetimes and budget of atmospheric components. Deposition amounts of sulfur and nitrogen compounds have been evaluated not only in East Asian region but also worldwide. On the other hand, atmospheric deposition of carbonaceous components including organic carbon (OC), elementary carbon (EC) and Polycyclic Aromatic Hydrocarbons (PAHs) were monitored only at a few sites in Europe, North America and Africa, which will obscure removal process and atmospheric concentration distribution of those components. In this study, ionic and carbonaceous components in precipitation and aerosol are monitored at remote sites in Japan, and the characteristics of atmospheric deposition amounts were evaluated.Field observations have been implemented at the Noto station since November 2013 and the Sado station since May 2011. Wet deposition samples were collected by rain samplers, and dry deposition samples were collected by high volume or low volume aerosol samplers. Concentrations of Cl-, NO3-, SO42-, NH4+, Na+, K+, Mg2+, Ca2+ were measured by ion chromatography, EC and OC by the IMPROVE protocol, and PAHs by HPLC with a fluorescence detector. Wet deposition amounts were calculated as the products of aqueous concentration and precipitation amounts, and dry deposition amounts were as the products of aerosol concentrations and deposition velocity estimated by the Inferential Method.Total (wet and dry) annual deposition amounts of carbonaceous components of NO3-, SO42-, EC, water insoluble OC, Fluoranthene at Noto (Nov. 2013 to Oct. 2014) were 4353.81 mg/m2, 7020.50 mg/m2, 149.84 mg/m2, 1191.09 mg/m2, 28.6 μg/m2, respectively. These amounts are comparable total annual deposition amounts of OC and EC at Sado (May 2011 to Feb. 2012), which were 166.04 mg/m2 and 834.0 mg/m2. Higher deposition amounts of ionic and carbonaceous components were observed, which would be attributable to long range transportation of the East Asian

  3. Atmospheric deposition in coniferous and deciduous tree stands in Poland

    NASA Astrophysics Data System (ADS)

    Kowalska, Anna; Astel, Aleksander; Boczoń, Andrzej; Polkowska, Żaneta

    2016-05-01

    The objective of this study was to assess the transformation of precipitation in terms of quantity and chemical composition following contact with the crown layer in tree stands with varied species composition, to investigate the effect of four predominant forest-forming species (pine, spruce, beech, and oak) on the amount and composition of precipitation reaching forest soils, and to determine the sources of pollution in atmospheric precipitation in forest areas in Poland. The amount and chemical composition (pH, electric conductivity, alkalinity, and chloride, nitrate, sulfate, phosphate, ammonium, calcium, magnesium, sodium, potassium, iron aluminum, manganese, zinc, copper, total nitrogen, and dissolved organic carbon contents) of atmospheric (bulk, BP) and throughfall (TF) precipitation were studied from January to December 2010 on twelve forest monitoring plots representative of Polish conditions. The study results provided the basis for the determination of the fluxes of pollutants in the forest areas of Poland and allowed the comparison of such fluxes with values provided in the literature for European forest areas. The transformation of precipitation in the canopy was compared for different tree stands. The fluxes of substances in an open field and under canopy were influenced by the location of the plot, including the regional meteorological conditions (precipitation amounts), vicinity of the sea (effect of marine aerosols), and local level of anthropogenic pollution. Differences between the plots were higher in TF than in BP. The impact of the vegetation cover on the chemical composition of precipitation depended on the region of the country and dominant species in a given tree stand. Coniferous species tended to cause acidification of precipitation, whereas deciduous species increased the pH of TF. Pine and oak stands enriched precipitation with components that leached from the canopy (potassium, manganese, magnesium) to a higher degree than spruce and

  4. Atmospheric Mercury Deposition Inferred from Glacial Records in the Tibetan Plateau: Modern Process and History

    NASA Astrophysics Data System (ADS)

    Zhang, Qianggong; Kang, Shichang; Zhang, Yulan

    2015-04-01

    Mercury (Hg) has been recognized as a global contaminant due to its intrinsic toxicity, biomagnifications in ecosystems, and long-range transport via the atmosphere. Atmospheric Hg deposition was evaluated using snowpits and an ice core retrieved from glaciers over the Tibetan Plateau (TP). Results revealed a wide range of total Hg (THg) concentrations (<1 to 43.6 ng L-1) in glacier snow and a clear seasonal variations with higher values in winter than those in summer. Estimated atmospheric Hg depositional fluxes ranged from 0.74 to 7.89 μg m-2 yr-1. Consecutive snowpit sampling at Zhadang glacier in the southern TP during summer season revealed that Hg in glaciers is mainly preserved in the form of particulate-bound Hg, Hg tends to accumulate in dust-enriched stratums during its percolation down to lower snow stratums. The presence of dust layers, usually formed yearly in winter/spring seasons, likely act as effective "adsorbers" enhancing the preservation and seasonality of the atmospheric Hg deposition records in glaciers over the TP. A high-resolution Hg record reconstructed by the Mt.Geladiandong ice core provided insight into historical atmospheric Hg deposition during the past 500 years. Notable elevated THg concentrations and fluxes were observed since 1940s, which coincides the increase of global Hg production, especially the Asian Hg production history. Ice core reconstructed Hg depositional flux for post-1940s era is over 6 times of that for pre-20th centuries, which clearly indicated anthropogenic influences on the regional, and perhaps even the global atmospheric Hg background and deposition rate.

  5. Assessment of the Altitudinal Atmospheric Metal(loid) Deposition in a Mountainous City by Mosses.

    PubMed

    Li, Haixia; Zhang, Guoping; Liu, Hong; Li, Ling; Fu, Zhiping; Ouyang, Xiaoxue; Chen, Jingjing; Hu, Jian

    2015-08-01

    Samples of moss (Haplocladium microphyllum) were collected at different elevations on a mountain and four representative sites in Guiyang City, and the concentrations of metal(loid)s were determined by ICP-MS. The altitudinal deposition of soil-originated metals differed from that of anthropogenic metal(loid)s. The concentrations of soil-related elements decreased with elevation, indicating that these elements tend to deposit at lower elevations and their impact on the higher elevations is less. The concentrations of anthropogenic elements varied only slightly with elevation, indicating that the atmospheric deposition of these elements did not vary largely with elevation. The results of this study showed that the mosses at different locations may serve to indicate a vertical gradient of atmospheric metal(loid) deposition. PMID:26055166

  6. The biogeochemistry of an ombrotrophic bog: Evaluation of use as an archive of atmospheric mercury deposition

    SciTech Connect

    Benoit, J.M.; Fitzgerald, W.F.; Damman, A.W.H.

    1998-08-01

    The utility of ombrotrophic bogs as archives of atmospheric mercury deposition was assessed with an investigation in Arlberg Bog, Minnesota, US. Since the use of ombrotrophic bogs as archives depends on the immobility of deposited trace metals, the authors examined the postdepositional transport processes revealed by the solid-phase distributions of mercury and ancillary metals in this bog. They modeled metal speciation in bog pore-waters as a function of pe in order to understand metal behavior in ombrotrophic peat. Specifically, they considered the effect of water movement and resultant shifts in redox potential gradients on metal retention. The results indicate that Hg and Pb are immobile in ombrotrophic peat, so their distribution can be used to determine temporal changes in deposition. To substantiate the deposition estimates determined in this study, they emphasized the importance of confirming the validity of the dating scheme, assessing the degree of horizontal homogeneity in the accumulation record, and providing evidence for retention of Hg based on geochemical modeling. As recorded in Arlberg Bog, historic atmospheric Hg deposition increased gradually after the mid-1800s, peaked between 1950 and 1960, and may have declined thereafter. Preindustrial deposition was about 4 {micro}g/m{sup 2} year and recent deposition about 19 {micro}g/m{sup 2} year. The results of this study indicate that deposition at Arlberg Bog has been influenced by a regional and/or local-scale source.

  7. RESUSPENSION OF PLUTONIUM FROM CONTAMINATED LAND SURFACES: METEOROLOGICAL FACTORS

    EPA Science Inventory

    A literature review is presented in a discussion of the relevance of meteorological factors on the resuspension of plutonium from contaminated land surfaces. The physical processes of resuspension based on soil erosion work are described. Some of the models developed to simulate ...

  8. Deposition of Functional Coatings from an Acetylene-Containing Plasma at Atmospheric Pressure

    NASA Astrophysics Data System (ADS)

    Plevako, F. V.; Gorbatov, S. V.; Davidovich, P. A.; Prikhod‧ko, E. M.; Shushkov, S. V.; Krul‧, L. P.; Butovskaya, G. V.; Shakhno, O. V.; Gusakova, S. V.; Korolik, O. V.; Mazanik, A. V.

    2016-03-01

    Properties of thin coatings formed on polymer and glass substrates by plasma-enhanced chemical vapor deposition from a mixture of nitrogen with acetylene at atmospheric pressure were investigated. It was established that chemically stable transparent films with a mass ratio of fixed carbon and nitrogen C:N ~ 2:1 are formed on the surface of these substrates. When the deposition time was increased, arrays of dendrite-like structures were formed on the substrates.

  9. Nutrient availability and phytoplankton nutrient limitation across a gradient of atmospheric nitrogen deposition

    USGS Publications Warehouse

    Elser, J.J.; Kyle, M.; Steuer, L.; Nydick, K.R.; Baron, J.S.

    2009-01-01

    Atmospheric nitrogen (N) deposition to lakes and watersheds has been increasing steadily due to various anthropogenic activities. Because such anthropogenic N is widely distributed, even lakes relatively removed from direct human disturbance are potentially impacted. However, the effects of increased atmospheric N deposition on lakes are not well documented, We examined phytoplankton biomass, the absolute and relative abundance of limiting nutrients (N and phosphorus [P]), and phytoplankton nutrient limitation in alpine lakes of the Rocky Mountains of Colorado (USA) receiving elevated (>6 kg N??ha-1??yr-1) or low (<2 kg N??ha-1??yr-1) levels of atmospheric N deposition. Highdeposition lakes had higher NO3-N and total N concentrations and higher total N : total P ratios. Concentrations of chlorophyll and seston carbon (C) were 2-2.5 times higher in highdeposition relative to low-deposition lakes, while high-deposition lakes also had higher seston C:N and C:P (but not N:P) ratios. Short-term enrichment bioassays indicated a qualitative shift in the nature of phytoplankton nutrient limitation due to N deposition, as highdeposition lakes had an increased frequency of primary P limitation and a decreased frequency and magnitude of response to N and to combined N and P enrichment. Thus elevated atmospheric N deposition appears to have shifted nutrient supply from a relatively balanced but predominantly N-deficient regime to a more consistently P-limited regime in Colorado alpine lakes. This adds to accumulating evidence that sustained N deposition may have important effects on lake phytoplankton communities and plankton-based food webs by shifting the quantitative and qualitative nature of nutrient limitation. ?? 2009 by the Ecological Society of America.

  10. Acid deposition: atmospheric processes in eastern North America, a review of current scientific understanding

    SciTech Connect

    Not Available

    1983-01-01

    There is no observational evidence of a strong nonlinearity in the relationship between annual average total emissions and total deposition of sulfur in eastern North America. The finding is supported by theoretical calculations using the best available laboratory measurements of photochemical rate parameters. Currently available models of long-range atmospheric transport and transformation are not sufficiently developed to assess relationships between emissions from specific sources and deposition at specific receptor sites with high reliability.

  11. Atmospheric Deposition of Indium in the Northeastern United States: Flux and Historical Trends.

    PubMed

    White, Sarah Jane O; Keach, Carrie; Hemond, Harold F

    2015-11-01

    The metal indium is an example of an increasingly important material used in electronics and new energy technologies, whose environmental behavior and toxicity are poorly understood despite increasing evidence of detrimental health impacts and human-induced releases to the environment. In the present work, the history of indium deposition from the atmosphere is reconstructed from its depositional record in an ombrotrophic bog in Massachusetts. A novel freeze-coring technique is used to overcome coring difficulties posed by woody roots and peat compressibility, enabling retrieval of relatively undisturbed peat cores dating back more than a century. Results indicate that long-range atmospheric transport is a significant pathway for the transport of indium, with peak concentrations of 69 ppb and peak fluxes of 1.9 ng/cm2/yr. Atmospheric deposition to the bog began increasing in the late 1800s/early 1900s, and peaked in the early 1970s. A comparison of deposition data with industrial production and emissions estimates suggests that both coal combustion and the smelting of lead, zinc, copper, and tin sulfides are sources of indium to the atmosphere in this region. Deposition appears to have decreased considerably since the 1970s, potentially a visible effect of particulate emissions controls instated in North America during that decade. PMID:26426729

  12. Atmospheric Deposition and Critical Loads for Nitrogen and Metals in Arctic Alaska: Review and Current Status

    USGS Publications Warehouse

    Linder, Greg L.; Brumbaugh, William G.; Neitlich, Peter; Little, Edward

    2013-01-01

    To protect important resources under their bureau’s purview, the United States National Park Service’s (NPS) Arctic Network (ARCN) has developed a series of “vital signs” that are to be periodically monitored. One of these vital signs focuses on wet and dry deposition of atmospheric chemicals and further, the establishment of critical load (CL) values (thresholds for ecological effects based on cumulative depositional loadings) for nitrogen (N), sulfur, and metals. As part of the ARCN terrestrial monitoring programs, samples of the feather moss Hylocomium splendens are being col- lected and analyzed as a cost-effective means to monitor atmospheric pollutant deposition in this region. Ultimately, moss data combined with refined CL values might be used to help guide future regulation of atmospheric contaminant sources potentially impacting Arctic Alaska. But first, additional long-term studies are needed to determine patterns of contaminant deposition as measured by moss biomonitors and to quantify ecosystem responses at particular loadings/ ranges of contaminants within Arctic Alaska. Herein we briefly summarize 1) current regulatory guidance related to CL values 2) derivation of CL models for N and metals, 3) use of mosses as biomonitors of atmospheric deposition and loadings, 4) preliminary analysis of vulnerabilities and risks associated with CL estimates for N, 5) preliminary analysis of existing data for characterization of CL values for N for interior Alaska and 6) implications for managers and future research needs.

  13. Uncertainty analysis of atmospheric deposition simulation of radiocesium and radioiodine from Fukushima Daiichi Nuclear Power Plant

    NASA Astrophysics Data System (ADS)

    Morino, Yu; Ohara, Toshimasa; Yumimoto, Keiya

    2014-05-01

    Chemical transport models (CTM) played key roles in understanding the atmospheric behaviors and deposition patterns of radioactive materials emitted from the Fukushima Daiichi nuclear power plant (FDNPP) after the nuclear accident that accompanied the great Tohoku earthquake and tsunami on 11 March 2011. In this study, we assessed uncertainties of atmospheric simulation by comparing observed and simulated deposition of radiocesium (137Cs) and radioiodine (131I). Airborne monitoring survey data were used to assess the model performance of 137Cs deposition patterns. We found that simulation using emissions estimated with a regional-scale (~500 km) CTM better reproduced the observed 137Cs deposition pattern in eastern Japan than simulation using emissions estimated with local-scale (~50 km) or global-scale CTM. In addition, we estimated the emission amount of 137Cs from FDNPP by combining a CTM, a priori source term, and observed deposition data. This is the first use of airborne survey data of 137Cs deposition (more than 16,000 data points) as the observational constraints in inverse modeling. The model simulation driven by a posteriori source term achieved better agreements with 137Cs depositions measured by aircraft survey and at in-situ stations over eastern Japan. Wet deposition module was also evaluated. Simulation using a process-based wet deposition module reproduced the observations well, whereas simulation using scavenging coefficients showed large uncertainties associated with empirical parameters. The best-available simulation reproduced the observed 137Cs deposition rates in high-deposition areas (≥10 kBq m-2) within one order of magnitude. Recently, 131I deposition map was released and helped to evaluate model performance of 131I deposition patterns. Observed 131I/137Cs deposition ratio is higher in areas southwest of FDNPP than northwest of FDNPP, and this behavior was roughly reproduced by a CTM if we assume that released 131I is more in gas phase

  14. Atmospheric nitrogen deposition budget in a subtropical hydroelectric reservoir (Nam Theun II case study, Lao PDR)

    NASA Astrophysics Data System (ADS)

    Adon, Marcellin; Galy-Lacaux, Corinne; Serça, Dominique; Guerin, Frederic; Guedant, Pierre; Vonghamsao, Axay; Rode, Wanidaporn

    2016-04-01

    With 490 km² at full level of operation, Nam Theun 2 (NT2) is one of the largest hydro-reservoir in South East Asia. NT2 is a trans-basin hydropower project that diverts water from the Nam Theun river (a Mekong tributary) to the Xe Ban Fai river (another Mekong tributary). Atmospheric deposition is an important source of nitrogen (N), and it has been shown that excessive fluxes of N from the atmosphere has resulted in eutrophication of many coastal waters. A large fraction of atmospheric N input is in the form of inorganic N. This study presents an estimation of the atmospheric inorganic nitrogen budget into the NT2 hydroelectric reservoir based on a two-year monitoring (July 2010 to July 2012) including gas concentrations and precipitation. Dry deposition fluxes are calculated from monthly mean surface measurements of NH3, HNO3 and NO2 concentrations (passive samplers) together with simulated deposition velocities, and wet deposition fluxes from NH4+ and NO3- concentrations in single event rain samples (automated rain sampler). Annual rainfall amount was 2500 and 3160 mm for the two years. The average nitrogen deposition flux is estimated at 1.13 kgN.ha-1.yr-1 from dry processes and 5.52 kgN.ha-1.yr-1 from wet ones, i.e., an average annual total nitrogen flux of 6.6 kgN.ha-1.yr-1 deposited into the NT2 reservoir. The wet deposition contributes to 83% of the total N deposition. The nitrogen deposition budget has been also calculated over the rain tropical forest surrounding the reservoir. Due to higher dry deposition velocities above forested ecosystems, gaseous dry deposition flux is estimated at 4.0 kgN.ha-1.yr-1 leading to a total nitrogen deposition about 9.5 kgN.ha-1.yr-1. This result will be compared to nitrogen deposition in the African equatorial forested ecosystems in the framework of the IDAF program (IGAC-DEBITS-AFrica).

  15. Direct atmospheric deposition of water-soluble nitrogen to the Gulf of Maine

    NASA Astrophysics Data System (ADS)

    Jordan, C. E.; Talbot, R. W.

    2000-12-01

    Measurements were made at New Castle, New Hampshire, on the shore of the Gulf of Maine from 1994 to 1997 to assess direct atmospheric deposition of water-soluble nitrogen to the surface waters of the gulf. Daily dry deposition was highly variable and ranged from ˜ 1 to 144 μmol N m-2 d-1 (median 16 μmol N m-2 d-1). Wet deposition dominated dry deposition, contributing 80-90% of the total flux annually. Wet deposition was also highly variable and ranged from 3 to 4264 μmol N m-2 d-1 (median 214 μmol N m-2 d-1). Fog water nitrogen deposition could contribute as much as large precipitation nitrogen deposition events, in excess of 500 μmol N m-2d-1. Dissolved organic nitrogen (DON) in precipitation constituted only a small fraction (3%) of the total precipitation nitrogen flux most of the year, except in spring where it comprised 14%, on average, of the total. The total atmospheric direct nitrogen (ADN) deposition numbers reported here do not include the contributions of fog and DON as they were not sampled regularly over the course of this study. The total ADN flux ranged from 1 to 4262 μmol N m-2 d-1 (median 23 μmol N m-2 d-1), depositing 52 mmol N m-2 yr-1 to the surface waters of the Gulf of Maine, 3% of the total N input to those waters annually. However, this deposition was highly episodic with events over 500 μmol N m-2 d-1 occurring in 8% of the days sampled but contributing 56% of the total measured flux and events in excess of 1000 μmol N m-2 d-1 occurring in 2% of the samples and contributing 22% of the total measured flux. It is these large events that may influence biological productivity of the Gulf of Maine. The annual wet deposition of inorganic N measured at New Castle exceeded that reported by two National Atmospheric Deposition Program (NADP) sites by 42% on average of that reported from Cape Cod, Massachusetts, and by 69% ofthat at Mt. Dessert Island, Maine. Estimates of the episodic atmospheric nitrogen flux to the surface waters of the

  16. Iron in East Antarctic snow: Implications for atmospheric iron deposition and algal production in Antarctic waters

    NASA Astrophysics Data System (ADS)

    Edwards, Ross; Sedwick, Peter

    To evaluate the deposition and solubility of aerosol iron in the Antarctic seasonal sea ice zone (SSIZ), iron was measured in snow samples collected from three areas in the SSIZ (Prydz Bay, Dumont d'Urville Sea and Ross Sea) and one continental area (Princess Elizabeth Land) of East Antarctica. Concentrations of total-dissolvable iron (that soluble at pH ˜2) ranged from 20-2950 pg g-1, with the lowest concentrations measured in snow from the Dumont d'Urville Sea. Using estimates of snow accumulation rates, we calculate atmospheric iron deposition fluxes of 0.017-0.11 mg m-2 yr-1 (0.30-2.0 µmol m-2 yr-1), which are generally lower than previously published estimates. Measurements of iron in filtered meltwaters of snow samples from Prydz Bay and Princess Elizabeth Land suggest that ˜10-90% of the total atmospheric iron is readily soluble. Assuming our results to be broadly representative of atmospheric deposition over seasonally ice-covered, high-nutrient Antarctic waters, we use our mean estimates of atmospheric iron deposition (1.1 µmol m-2 yr-1) and solubility (32%) to calculate that atmospheric iron potentially supports annual phytoplankton production of 1.1 × 1012 mole C in the Antarctic SSIZ, which is less than 5% of the estimated total annual primary production in this ocean region.

  17. Contributions of atmospheric nitrogen deposition to U.S. estuaries: Summary and conclusions: Chapter 8

    USGS Publications Warehouse

    Stacey, Paul E.; Greening, Holly; Kremer, James N.; Peterson, David; Tomasko, David A.

    2001-01-01

    A NOAA project was initiated in 1998, with support from the U.S. EPA, to develop state-of-the-art estimates of atmospheric N deposition to estuarine watersheds and water surfaces and its delivery to the estuaries. Work groups were formed to address N deposition rates, indirect (from the watershed) yields from atmospheric and other anthropogenic sources, and direct deposition on the estuarine waterbodies, and to evaluate the levels of uncertainty within the estimates. Watershed N yields were estimated using both a land-use based process approach and a national (SPARROW) model, compared to each other, and compared to estimates of N yield from the literature. The total N yields predicted by the national model were similar to values found in the literature and the land-use derived estimates were consistently higher. Atmospheric N yield estimates were within a similar range for the two approaches, but tended to be higher in the land-use based estimates and were not wellcorrelated. Median atmospheric N yields were around 15% of the total N yield for both groups, but ranged as high as 60% when both direct and indirect deposition were considered. Although not the dominant source of anthropogenic N, atmospheric N is, and will undoubtedly continue to be, an important factor in culturally eutrophied estuarine systems, warranting additional research and management attention.

  18. Western Pacific atmospheric nutrient deposition fluxes, their impact on surface ocean productivity

    NASA Astrophysics Data System (ADS)

    Martino, M.; Hamilton, D.; Baker, A. R.; Jickells, T. D.; Bromley, T.; Nojiri, Y.; Quack, B.; Boyd, P. W.

    2014-07-01

    The atmospheric deposition of both macronutrients and micronutrients plays an important role in driving primary productivity, particularly in the low-latitude ocean. We report aerosol major ion measurements for five ship-based sampling campaigns in the western Pacific from ~25°N to 20°S and compare the results with those from Atlantic meridional transects (~50°N to 50°S) with aerosols collected and analyzed in the same laboratory, allowing full incomparability. We discuss sources of the main nutrient species (nitrogen (N), phosphorus (P), and iron (Fe)) in the aerosols and their stoichiometry. Striking north-south gradients are evident over both basins with the Northern Hemisphere more impacted by terrestrial dust sources and anthropogenic emissions and the North Atlantic apparently more impacted than the North Pacific. We estimate the atmospheric supply rates of these nutrients and the potential impact of the atmospheric deposition on the tropical western Pacific. Our results suggest that the atmospheric deposition is P deficient relative to the needs of the resident phytoplankton. These findings suggest that atmospheric supply of N, Fe, and P increases primary productivity utilizing some of the residual excess phosphorus (P*) in the surface waters to compensate for aerosol P deficiency. Regional primary productivity is further enhanced via the stimulation of nitrogen fixation fuelled by the residual atmospheric iron and P*. Our stoichiometric calculations reveal that a P* of 0.1 µmol L-1 can offset the P deficiency in atmospheric supply for many months. This study suggests that atmospheric deposition may sustain ~10% of primary production in both the western tropical Pacific.

  19. Mosses Indicating Atmospheric Nitrogen Deposition and Sources in the Yangtze River Drainage Basin, China

    NASA Astrophysics Data System (ADS)

    Xiao, Hua-Yun; Tang, Cong-Guo; Xiao, Hong-Wei; Liu, Xue-Yan; Liu, Cong-Qiang

    2010-07-01

    Characterizing the level and sources of atmospheric N deposition in a large-scale area is not easy when using physical monitoring. In this study, we attempted to use epilithic mosses (Haplocladium microphyllum (Hedw.)) as a bioindicator. A gradient of atmospheric N deposition from 13.8 kg N ha-1 yr-1 to 47.7 kg N ha-1 yr-1 was estimated on the basis of moss tissue N concentrations and the linear equation between them. The estimated results are reliable because the highest atmospheric N deposition occurred in the middle parts of the Yangtze River, where the highest TN concentrations were also observed. Moss δ15N values in cities and forests were found in distinctly different ranges of approximately -10‰ to -6‰ and approximately -2‰ to 2‰, respectively, indicating that the main N sources in most of these cities were excretory wastes and those in forests were soil emissions. A negative correlation between moss δ15N values and the ratios of NH4-N/NO3-N in deposition (y = -1.53 x + 1.78) has been established when the ratio increased from 1.6 to 6.5. On the basis of the source information, the negative moss δ15N values in this study strongly indicate that NHy-N is the dominant N form in N deposition in the whole drainage basin. These findings are supported by the existing data of chemical composition of local N deposition.

  20. Atmospheric concentrations and dry deposition fluxes of particulate trace metals in Salvador, Bahia, Brazil

    NASA Astrophysics Data System (ADS)

    de P. Pereira, Pedro A.; Lopes, Wilson A.; Carvalho, Luiz S.; da Rocha, Gisele O.; de Carvalho Bahia, Nei; Loyola, Josiane; Quiterio, Simone L.; Escaleira, Viviane; Arbilla, Graciela; de Andrade, Jailson B.

    Respiratory system is the major route of entry for airborne particulates, being the effect on the human organism dependent on chemical composition of the particles, exposure time and individual susceptibility. Airborne particulate trace metals are considered to represent a health hazard since they may be absorbed into human lung tissues during breathing. Fossil fuel and wood combustion, as well as waste incineration and industrial processes, are the main anthropic sources of metals to the atmosphere. In urban areas, vehicular emissions—and dust resuspension associated to road traffic—become the most important manmade source. This work investigated the atmospheric concentrations of TSP, PM 10 and elements such as iron, manganese, copper and zinc, from three different sites around Salvador Region (Bahia, Brazil), namely: (i) Lapa Bus Station, strongly impacted by heavy-duty diesel vehicles; (ii) Aratu harbor, impacted by an intense movement of goods, including metal ores and concentrates and near industrial centers and; (iii) Bananeira Village located on Maré Island, a non-vehicle-influenced site, with activities such as handcraft work and fishery, although placed near the port. Results have pointed out that TSP concentrations ranged between 16.9 (Bananeira) and 354.0 μg m -3 (Aratu#1), while for PM 10 they ranged between 30.9 and 393.0 μg m -3, both in the Lapa Bus Station. Iron was the major element in both Lapa Station and Aratu (#1 and #2), with average concentrations in the PM 10 samples of 148.9, 79.6 and 205.0 ng m -3, respectively. Zinc, on the other hand, was predominant in samples from Bananeira, with an average concentration of 145.0 ng m -3 in TSP samples, since no PM 10 sample was taken from this site. The main sources of iron in the Lapa Station and Aratu harbor were, respectively, soil resuspension by buses and discharge of solid granaries, as fertilizers and metal ores. On the other hand, zinc and copper in the bus station were mainly from

  1. Wet deposition of atmospheric inorganic nitrogen at five remote stations on the Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Liu, Y. W.; Xu-Ri; Wang, Y. S.; Pan, Y. P.; Piao, S. L.

    2015-06-01

    Alpine ecosystems on the Tibetan Plateau are sensitive to elevated nitrogen (N) deposition, and N wet deposition in this region has shown an increasing trend since the mid-20th century. However, the amount of N wet deposition on the Tibetan remains unclear, due in most part to the lack of direct observations. Using the Tibetan Observation and Research Platform network, we investigated wet deposition of the major ions (NO3-, Cl-, SO42-, NH4+, Na+, K+, Ca2+ and Mg2+) at five remote stations. At Southeast Tibet Station, Nam Co Station, Qomolangma Station, Ngari Station, and Muztagh Ata Station, the NH4+-N wet deposition was 0.63, 0.91, 1.61, 0.36 and 1.25 kg N ha-1 yr-1, respectively; the NO3--N wet deposition was 0.28, 0.35, 0.04, 0.08 and 0.3 kg N ha-1 yr-1, respectively; and the inorganic N deposition was 0.91, 1.26, 1.64, 0.44 and 1.55 kg N ha-1 yr-1, respectively. Combining our field observations with previous studies, the average wet deposition of atmospheric NH4+-N, NO3--N, and inorganic N on the Tibetan Plateau was estimated to be 1.17, 0.58 and 1.75 kg N ha-1 yr-1, respectively. The estimated NH4+-N : NO3--N ratio in precipitation on the Tibetan Plateau was 2 : 1. Compared to the present study, the inorganic N wet deposition for the entire Tibetan Plateau in previous studies, either through atmospheric chemistry transport model simulations or interpolations based on limited observations, has been highly overestimated. To clarify the total N deposition on the Tibetan Plateau, it is necessary to conduct long-term and large-scale monitoring of both wet and dry deposition of N in the future.

  2. Studies of Plutonium Aerosol Resuspension at the Time of the Maralinga Cleanup

    SciTech Connect

    Shinn, J

    2003-08-01

    At the former nuclear test site at Maralinga, South Australia, soil cleanup began in October 1996 with the objective to remove the potential for residual plutonium (Pu) exposures to the public. In this case the cleanup was to restore access to the closed test site. The proposed long-term land use was primarily to be a hunting area for Pitjantjatjara (Aboriginal) people, but also presumably to be available to the public who might have an interest in the history of the site. The long-term management objective for the site was to allow casual use, but to prohibit habitation. The goal of this study is to provide an evaluation of the Maralinga soil cleanup in terms of potential long-term public inhalation exposures to particulate Pu, and in terms of a contribution to planning and conducting any such soil Pu-cleanup. Such cleanups might be carried out for example, on the Nevada Test Site in the United States. For Pu that has been deposited on the soil by atmospheric sources of finely divided particles, the dominant exposure pathway to humans is by inhalation. Other exposure pathways are less important because the Pu particles become oxidized into a nearly insoluble form, do not easily enter into the food chain, nor are they significantly transferred through the intestine to the bloodstream should Pu become ingested. The purpose of this report is to provide results of the Pu resuspension measurements made before, during, and after the Pu cleanup at Maralinga, to compare these against similar measurements made elsewhere, and to interpret the results as they relate to potential long-term public exposures. (Exposures to Pu in dust plumes produced by mechanical disturbance during cleanup are considered short-term, unlikely to be significant for purposes of this report, and are not included). A considerable amount of research had been conducted at Maralinga by the Australian Radiation Laboratory, now the Australian Radiation Protection and Nuclear Safety Agency (ARPANSA

  3. LONG-RANGE ATMOSPHERIC TRANSPORT AND DEPOSITION OF ANTHROPOGENIC CONTAMINANTS AND THEIR POTENTIAL EFFECTS ON TERRESTRIAL ECOSYSTEMS

    EPA Science Inventory

    Through the processes of atmospheric transport and deposition, many anthropogenic contaminants such as industrial organics, pesticides, and trace metals have become widely distributed around the globe. ue to the phenomenon of long-range atmospheric transport, even the most remote...

  4. Modeling the resuspension of radionuclides in Ukranian regions impacted by Chernobyl fallout

    SciTech Connect

    Nair, S.K.; Thiessen, K.M.; Hoffman, F.O.

    1997-01-01

    Following the 1986 Chernobyl event, large amounts of radioactive materials were deposited in nearby areas. Concentrations of various radionuclides were measured in air and surface soil. To study the resuspension of radioactive particulate, three different exposure situations were developed on the basis of the collected data under the auspices of the international BIOMOVS II (BIOspheric MOdel Validation Study) project. Modelers were asked to predict seasonal air concentrations and resuspension factors at several locations at different distances from Chernobyl for six successive years following the accident. Measurements of radionuclide deposition on topsoil were provided for each site along with information on soil, vegetation, land use, surface roughness, meteorology, and climate. In this paper, the three exposure situations are described, along with the initial data set provided to the modelers; two modeling approaches used to make the endpoint predictions are also presented. After the model predictions were submitted, the measured air concentrations and resuspension factors were released to the modelers. Generally, the predictions were well within an order of magnitude of the measured values. Time-dependent trends in predictions and measurements were in good agreement with one of the models, which (a) explicitly accounted for loss processes in soil and (b) used calibration to improve its predictive capabilities. Reasons for variations between predictions and measurements, suggestions for the improvement of models, and conclusions from the model validation study are presented. 12 refs., 15 figs., 4 tabs.

  5. Atmospheric dry deposition in the vicinity of the Salton Sea, California - I: Air pollution and deposition in a desert environment

    USGS Publications Warehouse

    Alonso, R.; Bytnerowicz, A.; Boarman, W.I.

    2005-01-01

    Air pollutant concentrations and atmospheric dry deposition were monitored seasonally at the Salton Sea, southern California. Measurements of ozone (O 3), nitric acid vapor (HNO3), ammonia (NH3), nitric oxide (NO), nitrogen dioxide (NO2) and sulfur dioxide (SO 2) were performed using passive samplers. Deposition rates of NO 3-, NH4+, Cl-, SO 42-, Na+, K+ and Ca2+ to creosote bush branches and nylon filters as surrogate surfaces were determined for one-week long exposure periods. Maximum O3 values were recorded in spring with 24-h average values of 108.8 ??g m-3. Concentrations of NO and NO2 were low and within ranges of the non-urban areas in California (0.4-5.6 and 3.3-16.2 ??g m-3 ranges, respectively). Concentrations of HNO3 (2.0-6.7 ??g m-3) and NH 3 (6.4-15.7 ??g m-3) were elevated and above the levels typical for remote locations in California. Deposition rates of Cl-, SO42-, Na+, K+ and Ca2+ were related to the influence of sea spray or to suspended soil particles, and no strong enrichments caused by ions originated by human activities were detected. Dry deposition rates of NO3- and NH4+ were similar to values registered in areas where symptoms of nitrogen saturation and changes in species composition have been described. Deposition of nitrogenous compounds might be contributing to eutrophication processes at the Salton Sea. ?? 2005 Elsevier Ltd. All rights reserved.

  6. Atmospheric deposition of nitrogen over Czech forests: refinement of estimation of dry deposition for unmeasured nitrogen species

    NASA Astrophysics Data System (ADS)

    Hunova, Iva; Stoklasova, Petra; Kurfurst, Pavel; Vlcek, Ondrej; Schovankova, Jana

    2014-05-01

    The accurate quantification of atmospheric deposition is very important for assessment of ambient air pollution impacts on ecosystems. Our contribution presents an advanced approach to improved quantification of atmospheric deposition of nitrogen over Czech forests, merging available measured data and model results. The ambient air quality monitoring in the Czech Republic is paid an appreciable attention (Hůnová, 2001) due to the fact, that in the recent past its territory belonged to the most polluted parts of Europe (Moldan and Schnoor, 1992). The time trends and spatial patterns of atmospheric deposition were published (Hůnová et al. 2004, Hůnová et al. 2014). Nevertheless, it appears that the atmospheric deposition of nitrogen, particularly the dry deposition, is likely to be underestimated due to unavailability of data of certain nitrogen species as HNO3(g) and NH3. It is known that HNO3(g) may contribute significantly to the dry deposition of nitrogen even in regions with relatively low concentrations (Flechard et al., 2011). We attempted to substitute unmeasured nitrogen species using an Eulerian photochemical dispersion model CAMx, the Comprehensive Air Quality Model with extensions (ESSS, 2011), coupled with a high resolution regional numeric weather prediction model Aladin (Vlček, Corbet, 2011). Preliminary results for 2008 indicate that dry deposition of nitrogen, so far based on detailed monitoring of ambient NOx levels, is underestimated substantially. The dry deposition of N/NOx in 2008 reported by Ostatnická (2009) was about 0.5 g.m-2.year-1 over 99.5 % of the nation-wide area, while the contribution of unmeasured nitrogen species estimated by CAMx model were much higher. To be specific, the dry deposition of N/HNO3(g) accounted for 1.0 g.m-2.year-1, and N/NH3 for 1.6 g.m-2.year-1. In contrast, the deposition of N/HONO (g) with 0.001 g.m-2.year-1, N/PAN with 0.007 g.m-2.year-1, particulate N/NO3- with 0.002 g.m-2.year-1, and particulate N/NH4

  7. Wet deposition of atmospheric inorganic nitrogen at five remote sites in the Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Liu, Y. W.; Xu-Ri; Wang, Y. S.; Pan, Y. P.; Piao, S. L.

    2015-10-01

    Since the mid-20th century, nitrogen (N) deposition has shown an increasing trend in the Tibetan Plateau (TP), where alpine ecosystems are sensitive to elevated N deposition. However, the quantitative characterization of N deposition in the TP remains unclear, due in most part to the lack of in situ measurement. Using the Tibetan Observation and Research Platform network, we conducted short-term in situ measurements of major ions (NO3-, Cl-, SO42-, NH4+, Na+, K+, Ca2+, and Mg2+) wet deposition at five remote sites in the TP during 2011-2013. At Southeast Tibet Station, Nam Co Station, Qomolangma Station, Ngari Station, and Muztagh Ata Station, the NH4+-N wet deposition was 0.63, 0.68, 0.92, 0.36, and 1.25 kg N ha-1 yr-1, respectively; the NO3--N wet deposition was 0.28, 0.24, 0.03, 0.08, and 0.30 kg N ha-1 yr-1, respectively; and the inorganic N wet deposition was 0.91, 0.92, 0.94, 0.44, and 1.55 kg N ha-1 yr-1, respectively. The inorganic N wet deposition mainly occurred in the form of NH4+-N during summer at all sites. Results of enrichment factor analysis and principal component analysis demonstrated that both NH4+-N and NO3--N wet deposition in the TP were mainly influenced by anthropogenic activities. Backward trajectory analysis showed that the inorganic N deposition at Muztagh Ata Station was mainly transported from central Asia and the Middle East through westerlies. At Southeast Tibet Station, Nam Co Station, Qomolangma Station, and Ngari Station, the inorganic N deposition was mainly contributed by anthropogenic sources in south Asia, and was mainly transported by the Indian monsoon. Combining site-scale in situ measurements of inorganic N wet deposition in this and previous studies, the average wet deposition of atmospheric NH4+-N, NO3--N, and inorganic N in the TP was estimated to be 1.06, 0.51, and 1.58 kg N ha-1 yr-1, respectively. The average NH4+-N : NO3--N ratio in precipitation in the TP was approximately 2 : 1. Results from the present study

  8. Atmospheric deposition of nutrients to north Florida rivers: A multivariate statistical analysis. Final report. Master's thesis

    SciTech Connect

    Fu, J.

    1991-01-01

    Atmospheric nutrient input to the Apalachicola Bay estuary was studied because it has been demonstrated that atmospheric deposition can be a major source of nutrients to eastern U.S. estuaries. Besides the Apalachicola River, the Sopchoppy and the Ochlockonee were also selected for a comparative analysis. Receptor model, absolute principal of component analysis (APCA), and mass balance methods were applied in the study. The results of the study show that nitrogen is probably not a limiting nutrient in the three rivers because their N:P mole ratios are nearly 3 times higher than the Redfield ratio for photosynthesis. The total atmospheric nitrogen depositions in the three river watershed are at least as great as their river fluxes. In the Apalachicola River, the atmospheric source of nitrogen is found to be several times higher than the largest possible input of urban sewage. Atmospheric deposition, therefore, might be the dominant nitrogen source entering the estuary. The results of APCA show that Apalachicola River water is mainly a mixture of components that correspond in their compositions to aged rain, ground water, and fresh rain. Atmospheric nitrate deposition is the result of the air pollution, i.e., acid rain. The studies also show that the annual average deposition of nitrate has a narrow range, mainly from 5.8 to 11.5 kg/ha/yr in most of the NADP sites in the 8 southeastern states. Since all the software and data sets employed in the study are accessible nationwide, the methods could be applied in other watersheds.

  9. The geographic distribution of radionuclide deposition across the continental US from atmospheric nuclear testing.

    PubMed

    Simon, Steven L; Bouville, André; Beck, Harold L

    2004-01-01

    For the first time, calculations for the more than 3000 counties of the US have been completed that estimate the average deposition density (Bq m(-2)) of more than 40 radionuclides in fallout from atmospheric nuclear weapons tests conducted in the US (1951-1962) and 19 radionuclides from tests conducted elsewhere in the world (1952-1963). The geographic pattern of deposition across the US, as well as the amount of fallout deposited, varied significantly depending on whether the tests were conducted within or outside of the US. Fallout deposited from the Nevada Test Site (NTS) varied geographically as a result of dispersion and dilution in the atmosphere, the wind patterns following each test, and the occurrence of localized rainfall events. In general, states immediately east of the NTS received the highest deposition from tests conducted there. In contrast, the variation in deposition across the country from global fallout was less than for NTS fallout primarily reflecting variations in annual precipitation across larger regions. Hence, in the eastern and mid-western US, where rainfall is above the national average, higher levels of global fallout were deposited than in the more arid southwestern states. This paper presents a summary of the methods used and findings of our studies on fallout from NTS and global fallout, with emphasis on two of the most important radionuclides, (131)I and (137)Cs. PMID:15063539

  10. Assessment of toxicity in waters due to heavy metals derived from atmospheric deposition using Vibrio fischeri.

    PubMed

    Cukurluoglu, Sibel; Muezzinoglu, Aysen

    2013-01-01

    Water toxicity originating from the atmospheric deposition of six heavy metals (Cd, Cr, Cu, Ni, Pb, Zn) was investigated on Vibrio fischeri activity in Izmir, Turkey. A LUMIStox® test was applied to dry and wet deposition samples and metal solutions. The inhibition levels and effective toxicity concentrations of these samples and solutions were determined. Interactive toxicity effects among the metals were investigated. When the impacts of the synthetic single heavy metal solutions were compared with each other, a toxicity ranking of Cr>Cd>Pb>Cu>Zn>Ni was obtained in order of decreasing severity. The total effective concentrations of these six metals were in the ranges of 0.074-0.221 mg/L and 0.071-0.225 mg/L for receiving aqueous solutions of dry and wet atmospheric depositions, respectively. The toxicity data showed that the wet deposition samples were 15% more toxic than the dry deposition samples. The interactive toxicity effects of the heavy metals in both dry and wet deposition samples were classified as antagonistic. High levels of heavy metals deposited in dissolved form may constitute an important input in the biochemical cycle and may have significant impacts. PMID:23030388

  11. Atmospheric heavy metal deposition plumes adjacent to a primary lead-zinc smelter.

    PubMed

    van Alphen, M

    1999-09-15

    A method for the determination of atmospheric heavy metal deposition rates has been developed using 0.5-m2 deposition trays at 0.1 m from the ground. Trays were spaced at 150-m intervals along a 1500-m line 500 m east of a Pb-Zn smelter. Ten sampling events of 1-3-h duration were conducted under westerly wind conditions so as to determine the sources of heavy metals deposited near the smelter. Deposited materials were sampled from the trays using wipes. There was good agreement between deposition trays placed side-by-side and exposed in pairs. Under certain conditions, however, the method is not appropriate owing to the potential for local contamination. Geometric mean deposition rates for Pb, Zn, Fe, Cu, As and Cd averaged over a nominal plume width of 600 m amounted to 18.8, 22.2, 12.2, 0.614, 0.403 and 0.052 mg m-2 day-1, respectively. Gaussian deposition profiles were seen for Pb, Zn, Fe, Cu, As and Cd downwind from the blast furnace, sinter plant, and refinery area. Zinc deposition could also be attributed to a northern Zn production area. This northern site was not generally associated with elevated Pb deposition. On the basis of this work, the deposition of heavy metals in residential areas adjoining the smelter is likely to occur downwind from the smelter site, with deposition rates increasing with wind speed. The strategic measurement of heavy metal dry-deposition rates over short periods of time using large collection surfaces provides source-specific information not obtainable by conventional long-term 'passive' deposition sampling. Lower detection limits than those achieved here are likely to be achieved in non-smelter settings. Previous suggestions implicating a sink of city surface dusts as the probable source of Pb recontamination of residential settings in the absence of ongoing smelter emissions are not supported by this work. PMID:10535148

  12. Conditional vulnerability of plant diversity to atmospheric nitrogen deposition across the United States.

    PubMed

    Simkin, Samuel M; Allen, Edith B; Bowman, William D; Clark, Christopher M; Belnap, Jayne; Brooks, Matthew L; Cade, Brian S; Collins, Scott L; Geiser, Linda H; Gilliam, Frank S; Jovan, Sarah E; Pardo, Linda H; Schulz, Bethany K; Stevens, Carly J; Suding, Katharine N; Throop, Heather L; Waller, Donald M

    2016-04-12

    Atmospheric nitrogen (N) deposition has been shown to decrease plant species richness along regional deposition gradients in Europe and in experimental manipulations. However, the general response of species richness to N deposition across different vegetation types, soil conditions, and climates remains largely unknown even though responses may be contingent on these environmental factors. We assessed the effect of N deposition on herbaceous richness for 15,136 forest, woodland, shrubland, and grassland sites across the continental United States, to address how edaphic and climatic conditions altered vulnerability to this stressor. In our dataset, with N deposition ranging from 1 to 19 kg N⋅ha(-1)⋅y(-1), we found a unimodal relationship; richness increased at low deposition levels and decreased above 8.7 and 13.4 kg N⋅ha(-1)⋅y(-1) in open and closed-canopy vegetation, respectively. N deposition exceeded critical loads for loss of plant species richness in 24% of 15,136 sites examined nationwide. There were negative relationships between species richness and N deposition in 36% of 44 community gradients. Vulnerability to N deposition was consistently higher in more acidic soils whereas the moderating roles of temperature and precipitation varied across scales. We demonstrate here that negative relationships between N deposition and species richness are common, albeit not universal, and that fine-scale processes can moderate vegetation responses to N deposition. Our results highlight the importance of contingent factors when estimating ecosystem vulnerability to N deposition and suggest that N deposition is affecting species richness in forested and nonforested systems across much of the continental United States. PMID:27035943

  13. Conditional vulnerability of plant diversity to atmospheric nitrogen deposition across the United States

    USGS Publications Warehouse

    Simkin, Samuel M.; Allen, Edith B.; Bowman, William D.; Clark, Christopher M.; Belnap, Jayne; Brooks, Matthew L.; Cade, Brian S.; Collins, Scott L.; Geiser, Linda H.; Gilliam, Frank S.; Jovan, Sarah E.; Pardo, Linda H.; Schulz, Bethany K.; Stevens, Carly J.; Suding, Katharine N.; Throop, Heather L.; Waller, Donald M.

    2016-01-01

    Atmospheric nitrogen (N) deposition has been shown to decrease plant species richness along regional deposition gradients in Europe and in experimental manipulations. However, the general response of species richness to N deposition across different vegetation types, soil conditions, and climates remains largely unknown even though responses may be contingent on these environmental factors. We assessed the effect of N deposition on herbaceous richness for 15,136 forest, woodland, shrubland, and grassland sites across the continental United States, to address how edaphic and climatic conditions altered vulnerability to this stressor. In our dataset, with N deposition ranging from 1 to 19 kg N⋅ha−1⋅y−1, we found a unimodal relationship; richness increased at low deposition levels and decreased above 8.7 and 13.4 kg N⋅ha−1⋅y−1 in open and closed-canopy vegetation, respectively. N deposition exceeded critical loads for loss of plant species richness in 24% of 15,136 sites examined nationwide. There were negative relationships between species richness and N deposition in 36% of 44 community gradients. Vulnerability to N deposition was consistently higher in more acidic soils whereas the moderating roles of temperature and precipitation varied across scales. We demonstrate here that negative relationships between N deposition and species richness are common, albeit not universal, and that fine-scale processes can moderate vegetation responses to N deposition. Our results highlight the importance of contingent factors when estimating ecosystem vulnerability to N deposition and suggest that N deposition is affecting species richness in forested and nonforested systems across much of the continental United States.

  14. Does chronic nitrogen deposition during biomass growth affect atmospheric emissions from biomass burning?

    NASA Astrophysics Data System (ADS)

    Giordano, Michael R.; Chong, Joey; Weise, David R.; Asa-Awuku, Akua A.

    2016-03-01

    Chronic nitrogen deposition has measureable impacts on soil and plant health. We investigate burning emissions from biomass grown in areas of high and low NO x deposition. Gas and aerosol-phase emissions were measured as a function of photochemical aging in an environmental chamber at UC-Riverside. Though aerosol chemical speciation was not available, results indicate a systemic compositional difference between biomass grown in high and low deposition areas. Aerosol emissions from biomass grown in areas of high NO x deposition exhibit a lower volatility than biomass grown in a low deposition area. Furthermore, fuel elemental analysis, NO x emission rates, and aerosol particle number distributions differed significantly between the two sites. Despite the limited scale of fuels explored, there is strong evidence that the atmospheric emissions community must pay attention to the regional air quality of biomass fuels growth areas.

  15. Analysis of mass transport in an atmospheric pressure remote plasma-enhanced chemical vapor deposition process

    SciTech Connect

    Cardoso, R. P.; Belmonte, T.; Henrion, G.; Gries, T.; Tixhon, E.

    2010-01-15

    In remote microwave plasma enhanced chemical vapor deposition processes operated at atmospheric pressure, high deposition rates are associated with the localization of precursors on the treated surface. We show that mass transport can be advantageously ensured by convection for the heavier precursor, the lighter being driven by turbulent diffusion toward the surface. Transport by laminar diffusion is negligible. The use of high flow rates is mandatory to have a good mixing of species. The use of an injection nozzle with micrometer-sized hole enables us to define accurately the reaction area between the reactive species. The localization of the flow leads to high deposition rates by confining the reactive species over a small area, the deposition yield being therefore very high. Increasing the temperature modifies nonlinearly the deposition rates and the coating properties.

  16. Historical atmospheric mercury emissions and depositions in North America compared to mercury accumulations in sedimentary records

    NASA Astrophysics Data System (ADS)

    Pirrone, Nicola; Allegrini, Ivo; Keeler, Gerald J.; Nriagu, Jerome O.; Rossmann, Ronald; Robbins, John A.

    Gold and silver production in North America (included United States, Canada and Mexico) released a large amount of mercury to the atmosphere until well into this century when mercury (Hg) amalgamation was replaced by cyanide concentration. Since then, emissions from industries have been the dominant anthropogenic sources of atmospheric Hg in North America as a whole. Past Hg emissions from gold and silver extractions in North America during the 1800s do not show a clear evidence of atmospheric deposition occurred at the coring sites considered in this study. Estimated atmospheric emissions of Hg in North America peaked in 1879 (at about 1708 t yr -1) and 1920 (at about 940 t yr -1), primarily due to Hg emissions from gold and silver mining. After the Great Economic Depression (1929) Hg emissions peaked again in the 1947 (274 t yr -1), in 1970 (325 t yr -1) and in 1989 (330 t yr -1) as result of increased Hg emissions from industrial sources, though improvements in the emissions control technology in United States and Canada have been substantial. Estimates of total atmospheric deposition fluxes of Hg to water and terrestrial receptors were in the range of 14.3-19.8 μg m -2 yr -1 in North America as a whole, and averaged 135 μg m -2 yr -1 (global background + local emissions) in the Great Lakes. These values were in good agreement with recent estimates reported in literature. The comparison of atmospheric Hg deposition fluxes with Hg accumulation rates in sediment cores suggests that atmospheric deposition was the major source of Hg entering the lakes system at coring sites, however, important contributions to Lake Ontario sediment cores sites from 1940 to 1970 were likely originated from local point sources (i.e. direct discharges).

  17. Very narrow SiGe/Si quantum wells deposited by low-temperature atmospheric pressure chemical vapor deposition

    SciTech Connect

    Gruetzmacher, D.A.; Sedgwick, T.O.; Northrop, G.A.

    1993-05-01

    The optical, structural, and electrical properties of very narrow SiGe quantum wells grown by {open_quotes}ultra-clean{close_quotes} atmospheric pressure chemical vapor deposition (APCVD) are investigated. X-ray reflectivity data reveal abrupt interfaces with a root-mean-square roughness of not more than 0.2 nm. For the first time narrow (4.3 meV) excitonic photoluminescence (PL) spectra were obtained from APCVD grown samples containing SiGe wells with 12.5% to 32.5% Ge. For the narrowest wells PL doublets are observed which are attributed to atomic steps at the SiGe/Si interfaces. The Pl and x-ray diffractometry data show that process deposition control for well and barrier width is within the monolayer range. Resonant tunneling diodes fabricated with 2.5-mm-wide Si{sub 0.75}Ge{sub 0.25} wells show world record peak to valley ratios of 4.2. Magneto-transport measurements performed at high magnetic fields of two-dimensional hole gases exhibit pronounced Hall plateaus and well-defined Shubnikov de Hass oscillations, indicating high material quality. The results give evidence that atmospheric pressure chemical vapor deposition, which relies on gas switching sequences of the reactive gases in a hydrogen ambience, is able to produce interface abruptness comparable if not better than reported by any other technique. 22 refs., 7 figs.

  18. ATMOSPHERIC TRANSPORT AND DEPOSITION OF POLYCHLORINATED DIBENZO-P-DIOXINS AND DIBENZOFURANS

    EPA Science Inventory

    Polychlorinated dibenzo-p-dioxins (PCDD) and polychlorinated dibenzofurans (PCDF) are toxic compounds which are dispersed through the environment by atmospheric transport and deposition. It has been previously shown that there is a varying mixture of these compounds produced by c...

  19. DISCOVERING THE CAUSES, CONSEQUENCES, AND IMPLICATIONS OF ACID RAIN AND ATMOSPHERIC DEPOSITION

    EPA Science Inventory

    Much has been learned in recent years about air pollution, acid precipitation and atmospheric deposition and their effects on public welfare. There are still unanswered questions about certain aspects of these problems and possible strategies for their solution. Public concern ab...

  20. MODEL ASSESSMENT OF THE ANNUAL ATMOSPHERIC DEPOSITION OF TRACE METALS TO LAKE SUPERIOR

    EPA Science Inventory

    Mass balance studies indicate atmospheric deposition of toxic pollutants to the Great Lakes accounts for a significant portion of the total loading. dentifying the types and locations of both natural and anthropogenic sources of these loadings is imperative before effective and e...

  1. ATMOSPHERIC DEPOSITION OF PESTICIDES TO AN AGRICULTURAL WATERSHED OF THE CHESAPEAKE BAY

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Choptank River watershed, located on the Delmarva Peninsula of the Chesapeake Bay, is dominated by agricultural land use which makes it vulnerable to runoff and atmospheric deposition of pesticides. Agricultural and wildlife areas are in close proximity, and off-site losses of pesticides may co...

  2. INTERMEDIATE-RANGE GRID MODEL FOR ATMOSPHERIC SULFUR DIOXIDE AND SULFATE CONCENTRATIONS AND DEPOSITIONS

    EPA Science Inventory

    A three-dimensional time-dependent grid type model for two chemically reacting species which undergo atmospheric transport, diffusion and wet and dry deposition over a region of several hundred km is presented. Accuracy and sensitivity of the model are discussed. The model is app...

  3. ATMOSPHERIC DEPOSITION OF TOXIC METALS TO LAKE MICHIGAN: PRELIMINARY ANNUAL MODEL CALCULATIONS

    EPA Science Inventory

    Concern is growing for the environmental water quality of the Great Lakes. tmospheric deposition of toxic substances is recognized as a major pathway of contaminants to the water medium. o estimate the annual atmospheric loadings of five toxic metals -- arsenic (As), cadmium (Cd)...

  4. ATMOSPHERIC MERCURY DEPOSITION TO LAKE MICHIGAN DURING THE LAKE MICHIGAN MASS BALANCE STUDY

    EPA Science Inventory

    Wet and dry mercury (Hg) deposition were calculated to Lake Michigan using a hybrid receptor modeling framework. The model utilized mercury monitoring data collected during the Lake Michigan Mass Balance Study and the Atmospheric Exchange Over Lakes and Oceans Study together w...

  5. Beaufort Sea storm and resuspension modeling

    NASA Astrophysics Data System (ADS)

    Lintern, D. Gwyn; Macdonald, Robie W.; Solomon, Steven M.; Jakes, Hunter

    2013-11-01

    Along the shallow Beaufort Sea coast of the Arctic Ocean, storm events during the summer are responsible for significant sediment resuspension and transport. Given the paucity of data in this difficult field area, a model has been developed to be used as a tool towards investigation of these processes. Two contrasting set of conditions are modeled; one simulation for a relatively quiescent period and a second simulation for a period that included a moderate and typical northwesterly storm. Results for these two periods are compared with shallow-water current and wave data collected by instrumented moorings. For the calm period, the model did not predict specific events very well, whereas for the period with a strong storm, the model performed very well in predicting wave height and wave period, and less well in predicting currents. However, under both calm and stormy conditions, mean current speeds and mean current directions were predicted with sufficient accuracy to proceed to calculations of sediment transport. Sensitivity analysis showed that currents contribute very little to the wave dominated resuspension, but mean currents could be used for computing sediment transport quantities and directions. Measurements of storm surge were represented well by the model output, aligning perfecting with the building and waning storm, but with a slight overprediction at the peak of the storm. The reasonable reproduction of wave heights and periods, and of storm surge indicate that the model is responding well to the input parameters. The modeling suggests that the most significant sediment erosion occurs at the northern tips of the Mackenzie Delta and the Tuktoyaktuk Peninsula, and around the area of Herschal Island. The model also indicates that waves are not fully developed during a storm for the present day ice limited fetch, and that extending the fetch a further 100 km to simulate ice retreat led to wave heights at the coast being increased by 20 cm.

  6. 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.

  7. Biomagnetic monitoring of heavy metals contamination in deposited atmospheric dust, a case study from Isfahan, Iran.

    PubMed

    Norouzi, Samira; Khademi, Hossein; Cano, Angel Faz; Acosta, Jose A

    2016-05-15

    Tree leaves are considered as one of the best biogenic dust collectors due to their ability to trap and retain particulate matter on their surfaces. In this study, the magnetic susceptibility (MS) and the concentration of selected heavy metals of plane tree (Platanus orientalis L.) leaves and deposited atmospheric dust, sampled by an indirect and a direct method, respectively, were determined to investigate the relationships between leaf magnetic parameters and the concentration of heavy metals in deposited atmospheric dust. The objective was to develop a biomagnetic method as an alternative to the common ones used for determining atmospheric heavy metal contaminations. Plane tree leaves were monthly sampled on the 19th of May to November, 2012 (T1-T7), for seven months from 21 different sites in the city of Isfahan, central Iran. Deposited atmospheric dust samples were also collected using flat glass surfaces from the same sites on the same dates, except for T1. MS (χlf, χhf) values in washed (WL) and unwashed leaves (UL) as well as Cu, Fe, Mn, Ni, Pb, and Zn concentrations in UL and deposited atmospheric dust samples were determined. The results showed that the MS content with a biogenic source was low with almost no significant change during the sampling period, while an increasing trend was observed in the MS content of UL samples due to the deposition of heavy metals and magnetic particles on leaf surfaces throughout the plant growth. The latter type of MS content could be reduced through washing off by rain. Most heavy metals examined, as well as the Tomlinson pollution load index (PLI) in UL, showed statistically significant correlations with MS values. The correlation between heavy metals content in atmospheric dust deposited on glass surfaces and leaf MS values was significant for Cu, Fe, Pb, and Zn. Moreover, the similarity observed between the spatial distribution maps of leaf MS and deposited atmospheric dust PLI provided convincing evidence regarding

  8. 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.

  9. Atmospheric Nitrogen Deposition to the Oceans: Observation- and Model-Based Estimates

    NASA Astrophysics Data System (ADS)

    Baker, Alex; Altieri, Katye; Okin, Greg; Dentener, Frank; Uematsu, Mitsuo; Kanakidou, Maria; Sarin, Manmohan; Duce, Robert; Galloway, Jim; Keene, Bill; Singh, Arvind; Zamora, Lauren; Lamarque, Jean-Francois; Hsu, Shih-Chieh

    2014-05-01

    The reactive nitrogen (Nr) burden of the atmosphere has been increased by a factor of 3-4 by anthropogenic activity since the industrial revolution. This has led to large increases in the deposition of nitrate and ammonium to the surface waters of the open ocean, particularly downwind of major human population centres, such as those in North America, Europe and Southeast Asia. In oligotrophic waters, this deposition has the potential to significantly impact marine productivity and the global carbon cycle. Global-scale understanding of N deposition to the oceans is reliant on our ability to produce effective models of reactive nitrogen emission, atmospheric chemistry, transport and deposition (including deposition to the land surface). The Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP) recently completed a multi-model analysis of global N deposition, including comparisons to wet deposition observations from three regional networks in North America, Europe and Southeast Asia (Lamarque et al., Atmos. Chem. Phys., 13, 7977-8018, 2013). No similar datasets exist which would allow observation - model comparisons of wet deposition for the open oceans, because long-term wet deposition records are available for only a handful of remote island sites and rain collection over the open ocean itself is very difficult. In this work we attempt instead to use ~2600 observations of aerosol nitrate and ammonium concentrations, acquired chiefly from sampling aboard ships in the period 1995 - 2012, to assess the ACCMIP N deposition fields over the remote ocean. This database is non-uniformly distributed in time and space. We selected four ocean regions (the eastern North Atlantic, the South Atlantic, the northern Indian Ocean and northwest Pacific) where we considered the density and distribution of observational data is sufficient to provide effective comparison to the model ensemble. Two of these regions are adjacent to the land networks used in the ACCMIP

  10. Particle size effect for metal pollution analysis of atmospherically deposited dust

    NASA Astrophysics Data System (ADS)

    Al-Rajhi, M. A.; Al-Shayeb, S. M.; Seaward, M. R. D.; Edwards, H. G. M.

    The metallic compositions of 231 atmospherically deposited dust samples obtained from widely-differing environments in Riyadh city, Saudi Arabia, have been investigated in relation to the particle size distributions. Sample data are presented which show that particle size classification is very important when analysing dust samples for atmospheric metal pollution studies. By cross-correlation and comparison, it was found that the best way to express the results of the metal concentration trend was as an average of particle ratios. Correlations between the six metals studied, namely Pb, Cr, Ni, Cu, Zn and Li, were found for every particle size (eight categories) and reveal that the metal concentrations increased as the particle size decreased. On the basis of this work, it is strongly recommended that future international standards for metal pollutants in atmospherically deposited dusts should be based on particle size fractions.

  11. Wind Induced Sediment Resuspension in a Microtidal Estuary

    NASA Technical Reports Server (NTRS)

    Booth, J. G.; Miller, R. L.; McKee, B. A.; Leathers, R. A.

    1999-01-01

    Bottom sediment resuspension frequency, duration and extent (% of bottom sediments affected) were characterized for the fifteen month period from September 1995 to January 1997 for the Barataria Basin, LA. An empirical model of sediment resuspension as a function of wind speed, direction, fetch and water depth was derived from wave theory. Water column turbidity was examined by processing remotely sensed radiance information from visible and near-IR AVHRR imagery. Based on model predictions, wind induced resuspension occurred during all seasons of this study. Seasonal characteristics for resuspension reveal that late fall, winter and early spring are the periods of most frequent and intense resuspension. Model predictions of the critical wind speed required to induce resuspension indicate that winds of 4 m/s (averaged over all wind directions resuspend approximately 50% of bottom sediments in the water bodies examined. Winds of this magnitude (4 m/s) occurred for 80% of the time during the late fall, winter and early spring and for approximately 30% of the time during the summer. More than 50% of the bottom sedimets are resuspended throughout the year, indicating the importance of resuspension as a process affecting sediment and biogeochemical fluxes in the Barataria Basin.

  12. Gaseous dry deposition of atmospheric mercury: A comparison of two surface resistance models for deposition to semiarid vegetation

    SciTech Connect

    Heather A. Holmes; Eric R. Pardyjak; Kevin D. Perry; Michael L. Abbott

    2011-07-01

    In the United States, atmospheric mercury (Hg) deposition, from regional and international sources, is the largest contributor to increased Hg concentrations in bodies of water leading to bioaccumulation of methyl mercury in fish. In this work, modeled dry deposition velocities (vd) for gaseous Hg are calculated using two surface resistance parameterizations found in the literature. The flux is then estimated as the product of the species concentration and modeled vd. The calculations utilize speciated atmospheric mercury concentrations measured during an annual monitoring campaign in southern Idaho. Gaseous elemental mercury (GEM) and reactive gaseous mercury (RGM) were monitored with Tekran models 2537A and 1130, respectively. Two anemometers collected meteorological data, including one fast-response three-dimensional sonic anemometer to measure turbulence parameters. For the flux calculation, three resistances are required to model the mechanisms that transport gaseous Hg from the atmosphere to the surface, with the surface resistance being the largest source of error. Results from two surface resistance models are presented. In particular, the downward flux is sensitive to the choice of model and input parameters such as seasonal category and mesophyll resistance. A comparison of annual GEM and RGM fluxes calculated using the two models shows good agreement for RGM (3.2% difference for annual deposition); however, for the low-solubility species of GEM, the models show a 64% difference in annual fluxes, with a range of 32% to 200% in seasonal fluxes. Results indicate the importance of understanding the diurnal variation of the physical processes modeled in the surface resistance parameterization for vd.

  13. Paleolimnological evidence of variations in deposition of atmosphere-borne Polycyclic Aromatic Hydrocarbons (PAHs) in Ireland.

    PubMed

    O'Dwyer, B; Taylor, D

    2009-11-01

    Polycyclic Aromatic Hydrocarbons (PAHs) are ubiquitous in the environment and are produced by both natural and anthropogenic processes, principally from the incomplete combustion of organic matter. Levels of emissions of PAHs from the combustion of fossil fuels have increased rapidly over the last ca. 200 years. As PAHs have detrimental environmental and human health impacts, assessing spatial and temporal variations in environmental loadings has become a pressing issue in many industrialised and industrializing countries. The current paper reports spatial and temporal variations in levels of atmospheric deposition of PAHs recorded in sediment cores from three lakes in Ireland, the locations of which were selected on the basis of known geographic differences in the deposition of atmospheric pollutants. Thirteen PAH compounds were analysed for in samples of lake sediment that were assumed to represent contemporary/recent and historical (possibly reference) levels of deposition. A third sample was selected from each core on the basis of measured levels of spheroidal carbonaceous particles, which are regarded as a direct indicator of depositions from the industrial-level combustion of fossil fuels. Chronological control was provided by the (210)Pb dating technique which also allowed for the calculation of PAH flux. For the most part, and when compared with the limited published data, measured levels of PAH depositions were relatively low. However, levels of deposition of PAHs in the west of Ireland are higher now than previously, which is in contrast to a general trend of decreasing levels in Europe. PMID:19819521

  14. Atmospheric deposition patterns of (210)Pb and (7)Be in Cienfuegos, Cuba.

    PubMed

    Alonso-Hernández, Carlos M; Morera-Gómez, Yasser; Cartas-Águila, Héctor; Guillén-Arruebarrena, Aniel

    2014-12-01

    The radiometric composition of bulk deposition samples, collected monthly for one year, February 2010 until January 2011, at a site located in Cienfuegos (22° 03' N, 80° 29' W) (Cuba), are analysed in this paper. Measurement of (7)Be and (210)Pb activity concentrations were carried out in 12 bulk deposition samples. The atmospheric deposition fluxes of (7)Be and (210)Pb are in the range of 13.2-132 and 1.24-8.29 Bq m(-2), and their mean values are: 56.6 and 3.97 Bq m(-2), respectively. The time variations of the different radionuclide have been discussed in relation with meteorological factors and the mean values have been compared to those published in recent literature from other sites located at different latitudes. The annual average flux of (210)Pb and (7)Be were 47 and 700 Bq m(-2) y(-1), respectively. Observed seasonal variations of deposition data are explained in terms of different environmental features. The atmospheric deposition fluxes of (7)Be and (210)Pb were moderately well correlated with precipitation and well correlated with one another. The (210)Pb/(7)Be ratios in the monthly depositions samples varied in the range of 0.05-0.10 and showed a strong correlation with the number of rainy days. PMID:25233214

  15. Development and Implementation of Critical Loads for Atmospheric Deposition: Federal Land Management Implications

    NASA Astrophysics Data System (ADS)

    Porter, E. M.

    2004-12-01

    Critical loads for atmospheric deposition have been widely developed and used in Europe, Canada, and other countries. Critical loads are used to influence air pollution emissions reductions, thereby protecting and restoring aquatic and terrestrial ecosystems. In the United States, federal land management agencies are adopting the critical load concept as a potentially valuable resource management tool. Certain parks and wilderness areas are currently being affected by anthropogenic nitrogen and sulfur deposition. Effects of excess deposition include acidification, nitrogen enrichment, toxicity, and changes in biotic communities. Streams in both Shenandoah and Great Smoky Mountains National Parks are experiencing chronic and episodic acidification and brook trout fisheries in Shenandoah have been affected. High elevation ecosystems in Rocky Mountain National Park are undergoing subtle changes in aquatic and terrestrial ecosystems attributable to atmospheric deposition. Natural resources in many other federal areas have been affected or are at risk from deposition. Federal land managers are refining strategies for critical loads that include working with scientists to identify resources sensitive to deposition, defining resource protection criteria that will meet management objectives, and estimating and implementing critical loads. Critical loads will be used in resource management decisions and federal land management planning. They will be used to evaluate management actions and assess progress towards meeting management goals. Federal land managers will also communicate critical loads information to air pollution regulatory agencies to inform emissions management strategies for clean air.

  16. Open Air Silicon Deposition by Atmospheric Pressure Plasma under Local Ambient Gas Control

    NASA Astrophysics Data System (ADS)

    Naito, Teruki; Konno, Nobuaki; Yoshida, Yukihisa

    2015-09-01

    In this paper, we report open air silicon (Si) deposition by combining a silane free Si deposition technology and a newly developed local ambient gas control technology. Recently, material processing in open air has been investigated intensively. While a variety of materials have been deposited, there were only few reports on Si deposition due to the susceptibility to contamination and the hazardous nature of source materials. Since Si deposition is one of the most important processes in device fabrication, we have developed open air silicon deposition technologies in BEANS project. For a clean and safe process, a local ambient gas control head was designed. Process gas leakage was prevented by local evacuation, and air contamination was shut out by inert curtain gas. By numerical and experimental investigations, a safe and clean process condition with air contamination less than 10 ppm was achieved. Si film was deposited in open air by atmospheric pressure plasma enhanced chemical transport under the local ambient gas control. The film was microcrystalline Si with the crystallite size of 17 nm, and the Hall mobility was 2.3 cm2/V .s. These properties were comparable to those of Si films deposited in a vacuum chamber. This research has been conducted as one of the research items of New Energy and Industrial Technology Development Organization ``BEANS'' project.

  17. Atmospheric Deposition and Fate of Mercury in High-altitude Watersheds of the Rocky Mountains.

    NASA Astrophysics Data System (ADS)

    Campbell, D. H.; Mast, M. A.; Ingersoll, G. P.; Manthorne, D. J.; Krabbenhoft, D. P.; Taylor, H. E.; Aiken, G. R.; Schuster, P. F.; Reddy, M. M.

    2003-12-01

    Despite the potential for cold high-altitude ecosystems to act as sinks in the global mercury cycle, atmospheric deposition and fate of mercury have not been measured extensively at mountain sites in the Western United States. At Buffalo Pass in northwestern Colorado (the highest site in the national Mercury Deposition Network at 3234 m elevation), mercury in wet deposition was 9 μ gm-2 in 2000, comparable to many sites in the upper Midwestern United States where fish consumption advisories are widespread because of elevated levels of mercury from atmospheric deposition. Similar levels of mercury deposition were measured about 90 km east of Buffalo Pass at Loch Vale in Rocky Mountain National Park (RMNP) during 2002. Concentrations of total mercury in headwater streams in RMNP averaged 2-4 ngL-1 during spring and summer of 2001-2002. Higher concentrations were observed during snowmelt and rainfall events. Dissolved mercury was generally greater than particulate mercury in these clear mountain streams. Mercury and dissolved organic carbon peaked as soils were flushed during early snowmelt and rainy summer periods. Overall, mercury deposition was greater than mercury export, indicating accumulation in alpine/subalpine ecosystems; however, the mercury exported in streamflow may contribute substantially to mercury loading in downstream lakes and reservoirs where fish consumption advisories have increased. Methyl mercury concentrations measured in the streams in 2002 were generally near or less than detection limits, however, extreme drought conditions limited hydrologic flushing of soils and wetlands that may be sources of methyl mercury. In 2003, surface and ground water from various alpine and subalpine landscapes were sampled to determine sources and transport of total and methyl mercury. The elevated levels of mercury in atmospheric deposition indicate a need for better understanding of mercury cycling and transport in high-altitude ecosystems of Western North

  18. Nutrient and trace metals atmospheric deposition in the western Mediterranean: source apportionment

    NASA Astrophysics Data System (ADS)

    Desboeufs, Karine; Bon Nguyen, Elisabeth; Simeoni, Pasquale; Dulac, François

    2015-04-01

    Mediterranean Sea is a typical LNLC region particularly well adapted to assess the role of ocean-atmosphere exchanges. Throughout the summer stratification period when diffusion through the thermocline is low, atmospheric inputs become the main external source of nutrients to the surface open waters of the MS, mostly by wet deposition in the western basin.Here, we show a 3-yr time continuous series of nutrient (N, P) and trace metals (Cr, Cu, Fe, P, V, Zn) total deposition fluxes in Corsica. Between March 2008 and May 2011, a monitoring station was operated with a weekly sampling time step at Galeria (42.44°N; 8.65°E) on the western coast of Corsica in the framework of the projects DUNE (a Dust Experiment in a Low Nutrient Low Chlorophyll Ecosystem) and then ChArMEx (the Chemistry-Aerososl Mediterranean Experiment). Monthly fluxes were measured to assess the temporal variability of the measured elements over the Western Mediterranean. Nutrients deposition presented a clear seasonal pattern which was different for each studied nutrients, emphasizing a difference of sources for the nutrients. The results show no dust event larger than 0.68 g m-2 so that the maximum yearly flux was among the lowest ever observed in Corsica (1.7 g m-2 y-1). One dust deposition event could contribute up to 30% of yearly deposition fluxes of nutrient and trace metals, confirming the high temporal variability of atmospheric deposition. However a source apportionment work via statistical methods shows that the yearly deposition fluxes of considered nutrient and trace metals were dominated by anthropogenic sources, except for Fe. Acknowledgements: DUNE project was funded by ANR. ChArMEx (http://charmex.lsce.ipsl.fr) is funded by CNRS/INSU, ADEME, CEA and Météo-France in the framework of the programme MISTRALS (http://www.mistrals-home.org)

  19. Estimating Chemical Exchange between Atmospheric Deposition and Forest Canopy in Guizhou, China.

    PubMed

    Li, Wei; Gao, Fang; Liao, Xueqin

    2013-01-01

    To evaluate the effects of atmospheric deposition on forest ecosystems, wet-only precipitation and throughfall samples were collected in two forest types (Masson pine [ Lamb.] forests and mixed conifer and broadleaf forests) in the Longli forest in the Guizhou province of southwestern China for a period of 21 successive months from April 2007 to December 2008. The pH and chemical components of precipitation and throughfall were analyzed. In addition, the canopy budget model was applied to distinguish between in-canopy and atmospheric sources of chemical compounds. Canopy leaching and total potentially acidifying deposition fluxes were calculated. The results showed that the average pH and the concentration of ions in throughfall were higher than those in precipitation, with the exception of the NH concentration. Dry deposition of S and N accumulated more in Masson pine forests than in mixed conifer and broadleaf forests. Canopy leaching was the most significant source of base cations in forest throughfall, which was higher in the mixed forests than in the coniferous forests. Anions in throughfall deposition in Masson pine forests exceeded those in the mixed forests. Higher total potentially acidifying deposition fluxes reflected the more effective amounts of acid delivered to Masson pine forests compared with mixed conifer and broadleaf forests. In addition, acid deposition induced the leaching and loss of nutrient ions such as Mg, K, and Ca. Although the trees of the studied areas have not shown any symptoms of cation loss, a potentially harmful influence was engendered by atmospheric deposition in the two forest types in the Longli area. PMID:23673825

  20. Tracing industrial ammonium in atmospheric deposition in the Athabasca Oil Sands Region, Alberta, Canada

    NASA Astrophysics Data System (ADS)

    Mayer, B.; Proemse, B. C.; Fenn, M. E.

    2013-12-01

    The expanding industrial development in the Athabasca oil sands region (AOSR) in northeastern Alberta, Canada, has raised concerns about increasing nitrogen (N) emissions from oil sands operations and their potential effects on the surrounding terrestrial and aquatic ecosystems. Stable isotope techniques may help to trace industrial emissions provided that they are isotopically distinct from background isotope ratios of atmospheric N compounds. Ammonium deposition rates (NH4-N) typically exceed nitrate deposition rates (NO3-N) in the AOSR (Proemse et al., 2013), suggesting that emissions of reduced nitrogen compounds play a significant role for the atmospheric nitrogen budget in the AOSR. We collected atmospheric ammonium in open field bulk deposition and throughfall using ion exchange resins over ~6 months time periods from summer 2007 to summer 2011 located at distances between 3 to 113 km to one of the major oil sands developments in the AOSR. Ammonium deposition rates and δ15N-NH4 values were determined using ion chromatography and the ammonium diffusion method (Sebilo et al., 2004) on resin extracts. Atmospheric ammonium deposition rates in open field bulk collectors and throughfall collectors ranged from 1.0 to 4.7 kg ha-1 yr-1 NH4-N, and from 1.0 to 18.3 kg ha-1 yr-1 NH4-N, respectively. δ15N-NH4 values varied from -6.3 to +14.8‰ with the highest δ15N values typically associated with elevated NH4-N deposition rates. δ15N-NH4 values of up to +20.1‰ were observed for industrially emitted NH4 in particulate matter (PM2.5) emissions (Proemse et al., 2012) suggesting that industrial NH3 and NH4 emissions are associated with elevated δ15N values providing a potential tracer. Applying a two-end-member mixing analysis using a background δ15N-NH4 value of -3.6‰ for summer and -3.2‰ for winter periods revealed that particularly sites within ~30 km radius from the main oil sands developments are significantly affected by industrial contributions to

  1. Observation of sediment resuspension in Old Tampa Bay, Florida

    USGS Publications Warehouse

    Schoellhamer, David H.

    1990-01-01

    Equipment and methodology have been developed to monitor sediment resuspension at two sites in Old Tampa Bay. Velocities are measured with electromagnetic current meters and suspended solids and turbidity are monitored with optical backscatterance sensors. In late November 1989, a vertical array of instrument pairs was deployed from a permanent platform at a deep-water site, and a submersible instrument package with a single pair of instruments was deployed at a shallow-water site. Wind waves caused resuspension at the shallow-water site, but not at the deeper platform site, and spring tidal currents did not cause resuspension at either site.

  2. Atmospheric nitrogen deposition to the northwestern Pacific: seasonal variation and source attribution

    NASA Astrophysics Data System (ADS)

    Zhao, Y.; Zhang, L.; Pan, Y.; Wang, Y.; Paulot, F.; Henze, D. K.

    2015-09-01

    Rapid Asian industrialization has led to increased downwind atmospheric nitrogen deposition threatening the marine environment. We present an analysis of the sources and processes controlling atmospheric nitrogen deposition to the northwestern Pacific, using the GEOS-Chem global chemistry model and its adjoint model at 1/2° × 2/3° horizontal resolution over East Asia and its adjacent oceans. We focus our analyses on the marginal seas: the Yellow Sea and the South China Sea. Asian nitrogen emissions in the model are 28.6 Tg N a-1 as NH3 and 15.7 Tg N a-1 as NOx. China has the largest sources with 12.8 Tg N a-1 as NH3 and 7.9 Tg N a-1 as NOx; the high-NH3 emissions reflect its intensive agricultural activities. We find Asian NH3 emissions are a factor of 3 higher in summer than winter. The model simulation for 2008-2010 is evaluated with NH3 and NO2 column observations from satellite instruments, and wet deposition flux measurements from surface monitoring sites. Simulated atmospheric nitrogen deposition to the northwestern Pacific ranges 0.8-20 kg N ha-1 a-1, decreasing rapidly downwind of the Asian continent. Deposition fluxes average 11.9 kg N ha-1 a-1 (5.0 as reduced nitrogen NHx and 6.9 as oxidized nitrogen NOy) to the Yellow Sea, and 5.6 kg N ha-1 a-1 (2.5 as NHx and 3.1 as NOy) to the South China Sea. Nitrogen sources over the ocean (ship NOx and oceanic NH3) have little contribution to deposition over the Yellow Sea, about 7 % over the South China Sea, and become important (greater than 30 %) further downwind. We find that the seasonality of nitrogen deposition to the northwestern Pacific is determined by variations in meteorology largely controlled by the East Asian monsoon and in nitrogen emissions. The model adjoint further estimates that nitrogen deposition to the Yellow Sea originates from sources over China (92 % contribution) and the Korean peninsula (7 %), and by sectors from fertilizer use (24 %), power plants (22 %), and transportation (18

  3. The effect of atmospheric nitrogen deposition on marine nitrogen cycling throughout the global ocean

    NASA Astrophysics Data System (ADS)

    Somes, Christopher; Oschlies, Andreas

    2014-05-01

    The rapidly increasing rate of anthropogenic nitrogen deposition has the potential to perturb marine ecosystems and biogeochemical cycles because nitrogen is one of the major limiting nutrients in the ocean. We use an Earth System Climate Model that includes ocean biogeochemistry to assess the impact of atmospheric nitrogen deposition. Experiments are conducted where we artificially add nitrogen to nearly all locations individually throughout the global surface ocean using a nitrogen deposition rate of 700 mg N m-2 yr-1, which is consistent with modern estimates near industrial areas. We identify oceanic "biomes" that respond differently to atmospheric nitrogen deposition. (1) When nitrogen is deposited near oxygen minimum zones where water column denitrification occurs, locally increased primary production stimulates additional denitrification. Since water column denitrification removes 7 mol N for every mol N of newly formed organic matter respired, the global oceanic nitrogen inventory declines in response to nitrogen deposition in these areas. This slow, but steady decline persists for at least 1,000 years. (2) When nitrogen is deposited above shallow continental shelves where benthic denitrification occurs, our benthic denitrification model predicts an increase that is nearly equal to the nitrogen deposited and thus no net change in the global nitrogen inventory. (3) When nitrogen is deposited into the high latitude open ocean far removed from nitrogen fixation and denitrification, all of this deposited nitrogen initially accumulates in the ocean. This nitrogen eventually circulates into the tropical oxygen minimum zones where it fuels additional primary production and denitrification, which removes nitrogen at a rate equal to the deposition after 1,000 years and leads to a stable, but increased nitrogen inventory in our model. (4) When nitrogen is deposited into the open ocean where nitrogen fixation occurs, nitrogen fixation decreases due to less nitrogen

  4. Atmospheric dry deposition of sulfur and nitrogen in the Athabasca Oil Sands Region, Alberta, Canada.

    PubMed

    Hsu, Yu-Mei; Bytnerowicz, Andrzej; Fenn, Mark E; Percy, Kevin E

    2016-10-15

    Due to the potential ecological effects on terrestrial and aquatic ecosystems from atmospheric deposition in the Athabasca Oil Sands Region (AOSR), Alberta, Canada, this study was implemented to estimate atmospheric nitrogen (N) and sulfur (S) inputs. Passive samplers were used to measure ambient concentrations of ammonia (NH3), nitrogen dioxide (NO2), nitric acid/nitrous acid (HNO3/HONO), and sulfur dioxide (SO2) in the AOSR. Concentrations of NO2 and SO2 in winter were higher than those in summer, while seasonal differences of NH3 and HNO3/HONO showed an opposite trend, with higher values in summer. Concentrations of NH3, NO2 and SO2 were high close to the emission sources (oil sands operations and urban areas). NH3 concentrations were also elevated in the southern portion of the domain indicating possible agricultural and urban emission sources to the southwest. HNO3, an oxidation endpoint, showed wider ranges of concentrations and a larger spatial extent. Concentrations of NH3, NO2, HNO3/HONO and SO2 from passive measurements and their monthly deposition velocities calculated by a multi-layer inference model (MLM) were used to calculate dry deposition of N and S. NH3 contributed the largest fraction of deposited N across the network, ranging between 0.70-1.25kgNha(-1)yr(-1), HNO3/HONO deposition ranged between 0.30-0.90kgNha(-1)yr(-1), and NO2 deposition between 0.03-0.70kgNha(-1)yr(-1). During the modeled period, average dry deposition of the inorganic gaseous N species ranged between 1.03 and 2.85kgNha(-1)yr(-1) and SO4-S deposition ranged between 0.26 and 2.04kgha(-1)yr(-1). Comparisons with co-measured ion exchange resin throughfall data (8.51kgSha(-1)yr(-1)) indicate that modeled dry deposition combined with measured wet deposition (1.37kgSha(-1)yr(-1)) underestimated S deposition. Gas phase NH3 (71%) and HNO3 plus NO2 (79%) dry deposition fluxes dominated the total deposition of NH4-N and NO3-N, respectively. PMID:27295600

  5. Atmospheric deposition of nutrients, pesticides, and mercury in Rocky Mountain National Park, Colorado, 2002

    USGS Publications Warehouse

    Mast, M. Alisa; Campbell, Donald H.; Ingersoll, George P.; Foreman, William T.; Krabbenhoft, David P.

    2003-01-01

    Nutrients, current-use pesticides, and mercury were measured in atmospheric deposition during summer in Rocky Mountain National Park in Colorado to improve understanding of the type and magnitude of atmospheric contaminants being deposited in the park. Two deposition sites were established on the east side of the park: one at an elevation of 2,902 meters near Bear Lake for nutrients and pesticides, and one at an elevation of 3,159 meters in the Loch Vale watershed for mercury. Concentrations of nutrients in summer precipitation at Bear Lake ranged from less than 0.007 to 1.29 mg N/L (milligrams of nitrogen per liter) for ammonium and 0.17 to 4.59 mg N/L for nitrate and were similar to those measured at the Loch Vale National Atmospheric Deposition Network station, where nitrogen concentrations in precipitation are among the highest in the Rocky Mountains. Atrazine, dacthal, and carbaryl were the most frequently detected pesticides at Bear Lake, with carbaryl present at the highest concentrations (0.0079 to 0.0952 ?g/L (micrograms per liter), followed by atrazine (less than 0.0070 to 0.0604 ?g/L), and dacthal (0.0030 to 0.0093 ?g/L). Mercury was detected in weekly bulk deposition samples from Loch Vale in concentrations ranging from 2.6 to 36.2 ng/L (nanograms per liter). Concentrations in summer precipitation were combined with snowpack data from a separate study to estimate annual deposition rates of these contaminants in 2002. Annual bulk nitrogen deposition in 2002 was 2.28 kg N/ha (kilograms of nitrogen per hectare) at Bear Lake and 3.35 kg N/ha at Loch Vale. Comparison of wet and bulk deposition indicated that dry deposition may account for as much as 28 percent of annual nitrogen deposition, most of which was deposited during the summer months. Annual deposition rates for three pesticides were estimated as 45.8 mg/ha (milligrams per hectare) of atrazine, 14.2 mg/ha of dacthal, and 54.8 mg/ha of carbaryl. Because of much higher pesticide concentrations in

  6. Atmospheric nitrogen deposition: revisiting the question of the importance of the organic component.

    PubMed

    Cornell, Sarah E

    2011-10-01

    The organic component of atmospheric reactive nitrogen plays a role in biogeochemical cycles, climate and ecosystems. Although its deposition has long been known to be quantitatively significant, it is not routinely assessed in deposition studies and monitoring programmes. Excluding this fraction, typically 25-35%, introduces significant uncertainty in the determination of nitrogen deposition, with implications for the critical loads approach. The last decade of rainwater studies substantially expands the worldwide dataset, giving enough global coverage for specific hypotheses to be considered about the distribution, composition, sources and effects of organic-nitrogen deposition. This data collation and meta-analysis highlights knowledge gaps, suggesting where data-gathering efforts and process studies should be focused. New analytical techniques allow long-standing conjectures about the nature and sources of organic N to be investigated, with tantalising indications of the interplay between natural and anthropogenic sources, and between the nitrogen and carbon cycles. PMID:21131113

  7. Enhanced acid rain and atmospheric deposition of nitrogen, sulfur and heavy metals in Northern China

    NASA Astrophysics Data System (ADS)

    Pan, Y.; Wang, Y.

    2013-12-01

    Atmospheric deposition is known to be important mechanism reducing air pollution. In response to the growing concern on the potential effects of the deposited material entering terrestrial and aquatic environments as well as their subsequent health effects, since 2007 we have established a 10-site monitoring network in Northern China, where particularly susceptible to severe air pollution. Wet and dry deposition was collected using an automatic wet-dry sampler. The presentation will focus on the new results of atmospheric deposition flux for a number of chemical species, such as nutrients (e.g. nitrogen and phosphorus), acidic matters (e.g. sulfur and proton), heavy metals and Polycyclic Aromatic Hydrocarbons, etc. This is to our knowledge the first detailed element budget study in the atmosphere across Northern China. We find that: (1) Over the 3 year period, 26% of precipitation events in the target area were more acid than pH 5.60 and these acidic events occurred in summer and autumn. The annual volume-weighted mean (VWM) pH value of precipitation was lower than 5.60 at most sites, which indicated the acidification of precipitation was not optimistic. The primary ions in precipitation were NH4+, Ca2+, SO42- and NO3-, with 10-sites-average concentrations of 221, 216, 216 and 80 μeq L-1, respectively. The ratio of SO42- to NO3- was 2.7; suggesting SO42- was the dominant acid component. (2) The deposited particles were neutral in general and the pH value increased from rural area to industrial and coastal sites. It is not surprising to note that the annual VWM pH value of precipitation was higher than 5.60 at three urban sites (Beijing and Tianjin mega cities) and one coastal site near the Bohai Bay, considering the fact that high buffer capacity of alkaline component, gas NH3 and mineral aerosols, at these sites compared to other places. (3) The 10-sites annual total deposition amounts for sulfur and nitrogen compounds were 60 and 65 kg N/S ha-1 yr-1

  8. Laboratory exposure systems to simulate atmospheric degradation of building stone under dry and wet deposition conditions

    NASA Astrophysics Data System (ADS)

    Johnson, J. B.; Haneef, S. J.; Hepburn, B. J.; Hutchinson, A. J.; Thompson, G. E.; Wood, G. C.

    The design philosophy, construction and use of two exposure test systems are described, in which the objective is to simulate the degradation of stone samples under, respectively, the 'dry' and 'wet' deposition of atmospheric pollutants. Some element of realistic acceleration is possible in certain experiments. Particular emphasis is placed upon using known presentation rates of the pollutants, both in respect of typical depositions of pollutants and their oxidation products appropriate for an industrial atmosphere. In the dry deposition rig, SO 2, NO 2, NO, HCl and the oxidant O 3 are presented individually or together at realistic deposition rates. In the wet deposition apparatus, SO 2-4, NO -3 and Cl - at a pH of 3.5, simulating 'acid rain' but in a more concentrated form, are deposited. The dry deposition chamber can be operated at constant relative humidity (typically 84%) with pre-dried or precisely wetted stones to simulate episodic rain wetting, or using other methods of wet/dry cycling, which are also a feature of the wet deposition chamber. Heating and cooling of the samples is also possible, as is the use of shaped or coupled stones of different kinds such as are found in a building facade. The results are illustrated in terms of data on the weight change, the anion content of stone and run-off, the pH change of run-off and the total calcium reacted, using Portland stone, as a prelude to later papers in which behaviour of a whole matrix of stone types and environments is presented and discussed. Such an approach permits the eventual production of 'pollutant-material response' relationships and damage functions for comparison with and prediction of external exposure results.

  9. Reconciling modeled and observed atmospheric deposition of soluble organic nitrogen at coastal locations

    NASA Astrophysics Data System (ADS)

    Ito, Akinori; Lin, Guangxing; Penner, Joyce E.

    2014-06-01

    Atmospheric deposition of reactive nitrogen (N) species from air pollutants is a significant source of exogenous nitrogen in marine ecosystems. Here we use an atmospheric chemical transport model to investigate the supply of soluble organic nitrogen (ON) from anthropogenic sources to the ocean. Comparisons of modeled deposition with observations at coastal and marine locations show good overall agreement for inorganic nitrogen and total soluble nitrogen. However, previous modeling approaches result in significant underestimates of the soluble ON deposition if the model only includes the primary soluble ON and the secondary oxidized ON in gases and aerosols. Our model results suggest that including the secondary reduced ON in aerosols as a source of soluble ON contributes to an improved prediction of the deposition rates (g N m-2 yr-1). The model results show a clear distinction in the vertical distribution of soluble ON in aerosols between different processes from the primary sources and the secondary formation. The model results (excluding the biomass burning and natural emission changes) suggest an increase in soluble ON outflow from atmospheric pollution, in particular from East Asia, to the oceans in the twentieth century. These results highlight the necessity of improving the process-based quantitative understanding of the chemical reactions of inorganic nitrogen species with organics in aerosol and cloud water.

  10. The impact of atmospheric deposition of cadmium on dominant algal species in the East China Sea

    NASA Astrophysics Data System (ADS)

    Quan, Qiwei; Chen, Ying; Ma, Qingwei; Wang, Fujiang; Meng, Xi; Wang, Bo

    2016-04-01

    Cadmium (Cd) mainly derived from anthropogenic emissions can be transported through atmospheric pathway to marine ecosystem, affecting the phytoplankton community and primary productivity. In this study, we identified the toxicity threshold of Cd for phytoplankton under seawater conditions of the coastal East China Sea (ECS) through both laboratory and in situ mesocosm incubation experiments. The mesocosm experiment showed that Cd in low concentration (0.003 μg per μg chl a) was conducive to the growth of natural community and increased chl a productivity. In high concentration (0.03 μg per μg chl a) Cd acted as an inhibiting factor which decreased the total chl a productivity. The diatom community was found to be more sensitive to Cd toxicity than dinoflagellate, as the low concentration Cd showed toxicity to diatom but enhanced dinoflagellate growth. We noticed that the soluble Cd estimated from atmosphere deposition to the coastal ECS was below the toxicity threshold and the Cd deposition might promote phytoplankton growth in this region. In our laboratory experiments, adding Cd, similar to aerosol deposition, stimulated the growth of both dominant algal species Prorocentrum donghaiense Lu (dinoflagellate) and Skeletonema costatum (diatom). Adding Cd on a higher level inhibited the growth of both the species, but Skeletonema costatum seemed obviously more sensitive to toxicity. This indicates the potential impact of atmospheric deposition Cd on phytoplankton community succession in the ECS.

  11. Decreased atmospheric sulfur deposition across the Southeastern U.S.: when will watersheds release stored sulfate?

    PubMed

    Rice, Karen C; Scanlon, Todd M; Lynch, Jason A; Cosby, Bernard J

    2014-09-01

    Emissions of sulfur dioxide (SO2) to the atmosphere lead to atmospheric deposition of sulfate (SO4(2-)), which is the dominant strong acid anion causing acidification of surface waters and soils in the eastern United States. Since passage of the Clean Air Act and its Amendments, atmospheric deposition of SO2 in this region has declined by over 80%, but few corresponding decreases in streamwater SO4(2-) concentrations have been observed in unglaciated watersheds. We calculated SO4(2-) mass balances for 27 forested, unglaciated watersheds from Pennsylvania to Georgia, by using total atmospheric deposition (wet plus dry) as input. Many of these watersheds still retain SO4(2-), unlike their counterparts in the northeastern U.S. and southern Canada. Our analysis showed that many of these watersheds should convert from retaining to releasing SO4(2-) over the next two decades. The specific years when the watersheds crossover from retaining to releasing SO4(2-) correspond to a general geographical pattern of later net watershed release from north to south. The single most important variable that explained the crossover year was the runoff ratio, defined as the ratio of annual mean stream discharge to precipitation. Percent clay content and mean soil depth were secondary factors in predicting crossover year. The conversion of watersheds from net SO4(2-) retention to release anticipates more widespread reductions in streamwater SO4(2-) concentrations in this region. PMID:25046800

  12. Particle size distribution of halogenated flame retardants and implications for atmospheric deposition and transport.

    PubMed

    Okonski, Krzysztof; Degrendele, Céline; Melymuk, Lisa; Landlová, Linda; Kukučka, Petr; Vojta, Šimon; Kohoutek, Jiří; Čupr, Pavel; Klánová, Jana

    2014-12-16

    This study investigates the distribution of polybrominated diphenyl ethers (PBDEs), hexabromocyclododecane (HBCD) and a group of novel flame retardants (NFRs) on atmospheric aerosols. Two high volume cascade impactors were used to collect particulate fractions of ambient air over a one year period at urban and rural sites. The majority of FRs were found on the finest aerosols (<0.95 μm). Concentrations of HBCD were higher than those of ΣPBDEs. Moreover, we noted seasonality and spatial differences in particle size distributions, yet a large portion of the observed differences were due to differences in particulate matter (PM) itself. When normalized by PM, the size distributions of the FRs exhibited much greater heterogeneity. Differences existed between the FR distributions by molecular weight, with the higher molecular weight FRs (e.g., BDE-209, Dechlorane Plus) distributed more uniformly across all particulate size fractions. The seasonal, spatial, and compound-specific differences are of crucial importance when estimating dry and wet deposition of FRs as smaller aerosols have longer atmospheric residence times. Estimated wet and dry deposition of four representative FRs (BDE-47, BDE-209, HBCD, and Dechlorane Plus) using size-segregated aerosol data resulted in lower deposition estimates than when bulk aerosol data were used. This has implications for estimates of long-range atmospheric transport and atmospheric residence times, as it suggests that without size-specific distributions, these parameters could be underestimated for FRs. PMID:25380095

  13. Decreased atmospheric sulfur deposition across the southeastern U.S.: when will watersheds release stored sulfate?

    USGS Publications Warehouse

    Rice, Karen C.; Scanlon, Todd S.; Lynch, Jason A.; Cosby, Bernard J.

    2014-01-01

    Emissions of sulfur dioxide (SO2) to the atmosphere lead to atmospheric deposition of sulfate (SO42-), which is the dominant strong acid anion causing acidification of surface waters and soils in the eastern United States (U.S.). Since passage of the Clean Air Act and its Amendments, atmospheric deposition of SO2 in this region has declined by over 80%, but few corresponding decreases in stream-water SO42- concentrations have been observed in unglaciated watersheds. We calculated SO42- mass balances for 27 forested, unglaciated watersheds from Pennsylvania to Georgia, by using total atmospheric deposition (wet plus dry) as input. Many of these watersheds still retain SO42-, unlike their counterparts in the northeastern U.S. and southern Canada. Our analysis showed that many of these watersheds should convert from retaining to releasing SO42- over the next two decades. The specific years when the watersheds crossover from retaining to releasing SO42- correspond to a general geographical pattern of later net watershed release from north to south. The single most important variable that explained the crossover year was the runoff ratio, defined as the ratio of annual mean stream discharge to precipitation. Percent clay content and mean soil depth were secondary factors in predicting crossover year. The conversion of watersheds from net SO42- retention to release anticipates more widespread reductions in stream-water SO42- concentrations in this region.

  14. Characterization of atmospheric deposition and runoff water in a small suburban catchment.

    PubMed

    Lamprea, Katerine; Ruban, Véronique

    2011-07-01

    A study has been carried out as part of the mission assigned to IRSTV (Research Institute of Urban Sciences and Techniques), a federative research network supported by the Loire Valley Region, with the objective of characterizing atmospheric deposition, roof runoff and street runoff in a small (31 ha) suburban catchment in Nantes equipped with a separate sewer system. Trace metals, polycyclic aromatic hydrocarbons (PAHs) and pesticides were investigated. The characterization of atmospheric deposition reveals a high variability of trace metal concentrations, which could not be explained by rainfall characteristics. The relative abundance order of the metals was as follows: Zn > Cu > Cr approximately Ni > Cd. Organic pollutants, i.e., PAHs and pesticides, were only rarely detected in the atmospheric deposition. Zn and Pb appear to be the major contaminants in runoff water, whereas the concentrations of Ni, Cu, Cr, Cd, PAHs and pesticides tend to remain low. On the whole, concentrations were similar to the lowest range reported in the literature. According to statutory thresholds, runoff water quality is poor because of the high Pb and Zn concentrations. Based on scanning electron microscopy observations, atmospheric particles do not apparently differ from runoff particles, with a predominance of pollen, bacteria and particles resulting from soil erosion. Spherical organic particles produced during fuel combustion have also been observed. PMID:21882566

  15. Decreased Atmospheric Sulfur Deposition Across the Southeastern U.S.: When Will Watersheds Release Stored Sulfate?

    NASA Astrophysics Data System (ADS)

    Rice, K. C.; Scanlon, T. M.; Lynch, J. A.; Cosby, B. J., Jr.

    2014-12-01

    Emissions of sulfur dioxide (SO2) to the atmosphere lead to atmospheric deposition of sulfate (SO42-), which is the dominant strong acid anion causing acidification of surface waters and soils in the eastern United States (U.S.). Since passage of the Clean Air Act and its Amendments, atmospheric deposition of SO2 in this region has declined by over 80%, but few corresponding decreases in stream-water SO42- concentrations have been observed in unglaciated watersheds. We calculated SO42- mass balances for 27 forested, unglaciated watersheds from Pennsylvania to Georgia, by using total atmospheric deposition (wet plus dry) as input. Many of these watersheds still retain SO42-, unlike their counterparts in the northeastern U.S. and southern Canada. Our analysis showed that many of these watersheds should convert from retaining to releasing SO42- over the next two decades. The specific years when the watersheds crossover from retaining to releasing SO42- correspond to a general geographical pattern of later net watershed release from north to south. The single most important variable that explained the crossover year was the runoff ratio, defined as the ratio of annual mean stream discharge to precipitation. Percent clay content and mean soil depth were secondary factors in predicting crossover year. The conversion of watersheds from net SO42- retention to release anticipates more widespread reductions in stream-water SO42- concentrations in this region.

  16. Evidence for Open-Ocean Atmospheric Deposition of Lignin as a Significant Source of Chromophoric Dissolved Organic Matter in the North Atlantic Subtropical Gyre

    NASA Astrophysics Data System (ADS)

    Bocarsly, J. D.; McDonald, N.; Peters, A.; Nelson, N. B.

    2012-12-01

    Chromophoric dissolved organic matter (CDOM) has been studied extensively for its role in shaping the oceanic underwater light field. While much is understood about the chemical composition and properties of coastal CDOM, its source, composition, fate and transport in the open ocean remain relatively unknown. Notably, data from the last decade suggest that water mass movement and resuspension and horizontal transport of sediments alone are not enough to account for the presence of terrestrial-source CDOM in the open ocean. In this study, we investigated atmospheric deposition as a potential source of terrestrial CDOM in the open ocean. Lignin, a polymer found only in vascular plants, served as a tracer for terrestrially derived CDOM. Selected individual lignin phenols were quantified in aerosol and seawater samples using GC-MS analysis. In addition to quantitative data, ratios of the concentrations of these methoxy phenols give qualitative information about the source and degree of photodegradation of the source lignin. A high volume air sampler (2.88m3/min) was used to sample aerosol particles <10 μm in diameter at the Bermuda Atlantic Time Series site (31 40.00 N, 64 10.00 W), in the Sargasso Sea. Concurrently, water samples were collected from the ocean surface, local bacterial maximum, and deep chlorophyll maximum. In addition, samples of Sargassum macroalgae as well as particulate organic matter were collected to study potential additional sources of open ocean surface CDOM. Consistently, lignin phenols were present in the aerosol samples and their relative concentrations resembled those of the lignin phenols detected in surface water. The aerosol lignin phenol composition did not, on the other hand, resemble that found in deeper ocean water. Low levels of sodium ion quantified via ion chromatography in the aerosol samples demonstrate that seawater from sea spray is not a significant source of the sampled aerosol. These results suggest that atmospheric

  17. [Pollution evaluation and health risk assessment of heavy metals from atmospheric deposition in Lanzhou].

    PubMed

    Li, Ping; Xue, Su-Yin; Wang, Sheng-Li; Nan, Zhong-Ren

    2014-03-01

    In order to evaluate the contamination and health risk of heavy metals from atmospheric deposition in Lanzhou, samples of atmospheric deposition were collected from 11 sampling sites respectively and their concentrations of heavy metals were determined. The results showed that the average contents of Cu, Pb, Cd, Cr, Ni, Zn and Mn were 82.22, 130.31, 4.34, 88.73, 40.64, 369.23 and 501.49 mg x kg(-1), respectively. There was great difference among different functional areas for all elements except Mn. According to the results, the enrichment factor score of Mn was close to 1, while the enrichment of Zn, Ni, Cu and Cr was more serious, and Pb and Cd were extremely enriched. The assessment results of geoaccumulation index of potential ecological risk indicated that the pollution of Cd in the atmospheric deposition of Lanzhou should be classified as extreme degree, and that of Cu, Ni, Zn, Pb as between slight and extreme degrees, and Cr as practically uncontaminated. Contaminations of atmospheric dust by heavy metals in October to the next March were more serious than those from April to August. Health risk assessment indicated that the heavy metals in atmospheric deposition were mainly ingested by human bodies through hand-mouth ingestion. The non-cancer risk was higher for children than for adults. The order of non-cancer hazard indexes of heavy metals was Pb > Cr > Cd > Cu > Ni > Zn. The non-cancer hazard indexes and carcinogen risks of heavy metals were both lower than their threshold values, suggesting that they will not harm the health. PMID:24881392

  18. Atmospheric deposition and watershed nitrogen export along an elevational gradient in the Catskill Mountains, New York

    USGS Publications Warehouse

    Lawrence, G.B.; Lovett, Gary M.; Baevsky, Y.H.

    2000-01-01

    Cumulative effects of atmospheric N deposition may increase N export from watersheds and contribute to the acidification of surface waters, but natural factors (such as forest productivity and soil drainage) that affect forest N cycling can also control watershed N export. To identify factors that are related to stream-water export of N, elevational gradients in atmospheric deposition and natural processes were evaluated in a steep, first-order watershed in the Catskill Mountains of New York, from 1991 to 1994. Atmospheric deposition of SO4/2-, and probably N, increased with increasing elevation within this watershed. Stream-water concentrations of SO4/2- increased with increasing elevation throughout the year, whereas stream-water concentrations of NO3/- decreased with increasing elevation during the winter and spring snowmelt period, and showed no relation with elevation during the growing season or the fall. Annual export of N in stream water for the overall watershed equaled 12% to 17% of the total atmospheric input on the basis of two methods of estimation. This percentage decreased with increasing elevation, from about 25% in the lowest subwatershed to 7% in the highest subwatershed; a probable result of an upslope increase in the thickness of the surface organic horizon, attributable to an elevational gradient in temperature that slows decomposition rates at upper elevations. Balsam fir stands, more prevalent at upper elevations than lower elevations, may also affect the gradient of subwatershed N export by altering nitrification rates in the soil. Variations in climate and vegetation must be considered to determine how future trends in atmospheric deposition will effect watershed export of nitrogen.

  19. Atmospheric nitrogen deposition to the northwestern Pacific: seasonal variation and source attribution

    NASA Astrophysics Data System (ADS)

    Zhao, Yuanhong; Zhang, Lin; Pan, Yuepeng; Wang, Yuesi; Paulot, Fabien; Henze, Daven

    2016-04-01

    Rapid Asian industrialization has lead to increased atmospheric nitrogen deposition downwind threatening the marine environment. We present an analysis of the sources and processes controlling atmospheric nitrogen deposition to the northwestern Pacific, using the GEOS-Chem global chemistry model and its adjoint model at 1/2°× 2/3° horizontal resolution over the East Asia and its adjacent oceans. We focus our analyses on the marginal seas: the Yellow Sea and the South China Sea. Asian nitrogen emissions in the model are 28.6 Tg N a-1 as NH3 and 15.7 Tg N a-1 as NOx. China has the largest sources with 12.8 Tg N a-1 as NH3 and 7.9 Tg N a-1 as NOx; the much higher NH3 emissions reflect its intensive agricultural activities. We improve the seasonality of Asian NH3 emissions; emissions are a factor of 3 higher in summer than winter. The model simulation for 2008-2010 is evaluated with NH3 and NO2 column observations from satellite instruments, and wet deposition flux measurements from surface monitoring sites. Simulated atmospheric nitrogen deposition to the northwestern Pacific ranges 0.8-20 kg N ha-1 a-1, decreasing rapidly downwind the Asian continent. Deposition fluxes average 11.9 kg N ha-1 a-1 (5.0 as reduced nitrogen NHx and 6.9 as oxidized nitrogen NOy) to the Yellow Sea, and 5.6 kg N ha-1 a-1 (2.5 as NHx and 3.1 as NOy) to the South China Sea. Nitrogen sources over the ocean (ship NOx and oceanic NH3) have little contribution to deposition over the Yellow Sea, about 7% over the South China Sea, and become important (greater than 30%) further downwind. We find that the seasonality of nitrogen deposition to the northwestern Pacific is determined by variations in meteorology largely controlled by the East Asian Monsoon and in nitrogen emissions. The model adjoint further points out that nitrogen deposition to the Yellow Sea originates from sources over China (92% contribution) and the Korean peninsula (7%), and by sectors from fertilizer use (24%), power plants

  20. Status and trends in atmospheric deposition and emissions near Atlanta, Georgia, 1986-99

    USGS Publications Warehouse

    Peters, N.E.; Meyers, T.P.; Aulenbach, Brent T.

    2002-01-01

    Wet and dry atmospheric deposition were investigated from weekly data, 1986-99 (1986-97 for dry deposition) at the Panola Mountain Research Watershed (PMRW), a forested research site 25 km, southeast of Atlanta, Georgia. Furthermore, the wet deposition was compared to that at three adjacent National Atmospheric Deposition Program's National Trends Network (NTN) sites (GA41, 50 km south of PMRW; AL99, 175 km northwest; NC25, 175 km north-northeast) and dry deposition was compared to that at adjacent Clean Air Status and Trends Network (CASTNET) sites, co-located at the NTN sites. The pH of precipitation is acidic and the dominant acid anion is SO4; the pH (derived from the volume-weighted mean H concentration) averages 4.44 for 1986-99, and varies seasonally with average lowest values in summer (4.19) and highest in winter (4.63). From 1986-99, the annual wet deposition of sulfur (S) and nitrogen (N) averaged 400 and 300 eq ha-1 (6.4 and 4.2 kg ha-1), respectively. Inferential model estimates of annual dry S and N deposition from 1986-97 averaged 130 and 150 eq ha-1 (2.1 and 2.1 kg ha-1), respectively. From 1993-99, net S deposition (dry deposition plus canopy interactions) for coniferous and deciduous throughfall (throughfall minus wet-only deposition) averaged 400 and 150 eq ha-1 (6.4 and 2.1 kg ha-1), respectively. The annual wet deposition of S and N species at PMRW was comparable to that at NTN sites, with the exception of higher N species deposition at AL99 and relatively lower H, SO4 and NO3 deposition at GA41. Dry S deposition at PMRW differed markedly from the CASTNET sites despite similarity in S concentrations for all but NC25; the differences are attributed to differences in model parameters associated with the landscape and vegetation characteristics at the sites. At PMRW, atmospheric deposition trends were not detected for the entire sampling period, but were detected for shorter periods (4-5yr). Annual S and N deposition increased from 1986 to 1991

  1. Atmospheric occurrence, transport and deposition of polychlorinated biphenyls and hexachlorobenzene in the Mediterranean and Black Seas

    NASA Astrophysics Data System (ADS)

    Berrojalbiz, N.; Castro-Jiménez, J.; Mariani, G.; Wollgast, J.; Hanke, G.; Dachs, J.

    2014-04-01

    The Mediterranean and Black Seas are unique marine environments subject to important anthropogenic pressures due to direct and indirect loads of atmospheric inputs of organochlorine compounds (OCl) from primary and secondary sources. Here we report the results obtained during two east-west sampling cruises in June 2006 and May 2007 from Barcelona to Istanbul and Alexandria, respectively, where gas phase and aerosol samples were collected. Both matrices were analyzed for 41 polychlorinated biphenyls (PCBs), including dioxin-like congeners, and hexachlorobencene (HCB). The values reported in this study for gas phase HCB and ∑41PCB (LOD to 418.3 pg m-3 and from 81.99 to 931.6 pg m-3 respectively) are in the same range of those reported in former studies, possibly suggesting a limited decline in their atmospheric concentrations during the last decade for the Mediterranean region due to land base OCl sources. There is a clear influence of the direction of the air-mass on the atmospheric concentrations of PCBs, with higher concentrations when the air mass was from southern Europe, and the lowest concentrations for air masses coming from the SW Mediterranean and Atlantic Ocean. PCBs and HCB are close to air-water equilibrium for most sampling periods, thus resulting in low atmospheric deposition fluxes at open sea. This is consistent with the oligotrophic character of the Mediterranean Sea with a small influence of the biological pump capturing atmospheric PCBs. Therefore, degradation of gas-phase PCBs by OH radicals is estimated to be the main loss process of atmospheric PCBs during their transport over the Mediterranean Sea. Conversely, atmospheric residence times of HCB are predicted to be very long due to a lack of atmospheric degradation and low depositional fluxes due to concentrations at air-water equilibrium.

  2. Atmospheric occurrence, transport and deposition of polychlorinated biphenyls and hexachlorobenzene in the Mediterranean and Black seas

    NASA Astrophysics Data System (ADS)

    Berrojalbiz, N.; Castro-Jiménez, J.; Mariani, G.; Wollgast, J.; Hanke, G.; Dachs, J.

    2014-09-01

    The Mediterranean and Black seas are unique marine environments subject to important anthropogenic pressures due to direct and indirect loads of atmospheric inputs of organochlorine compounds (OCls) from primary and secondary sources. Here we report the results obtained during two east-west sampling cruises in June 2006 and May 2007 from Barcelona to Istanbul and Alexandria, respectively, where gas-phase and aerosol-phase samples were collected. Both matrices were analyzed for 41 polychlorinated biphenyls (PCBs), including dioxin-like congeners, and hexachlorobenzene (HCB). The values reported in this study for gas-phase HCB and ∑41PCB limit of detection (LOD) to 418.3 pg m-3 and from 81.99 to 931.6 pg m-3 respectively) are in the same range of those reported in former studies, possibly suggesting a limited decline in their atmospheric concentrations during the last decade for the Mediterranean region due to land-based OCl sources. There is a clear influence of the direction of the air mass on the atmospheric concentrations of PCBs, with higher concentrations when the air mass was from southern Europe, and the lowest concentrations for air masses coming from the SW Mediterranean and Atlantic Ocean. PCBs and HCB are close to air-water equilibrium for most sampling periods, thus resulting in low atmospheric deposition fluxes at open sea. This is consistent with the oligotrophic character of the Mediterranean Sea with a small influence of the biological pump capturing atmospheric PCBs. Therefore, degradation of gas-phase PCBs by OH radicals is estimated to be the main loss process of atmospheric PCBs during their transport over the Mediterranean Sea. Conversely, atmospheric residence times of HCB are predicted to be very long due to a lack of atmospheric degradation and low depositional fluxes due to concentrations at air-water equilibrium.

  3. Evaluation of atmospheric deposition of nitrogen to the Feitsui reservoir in Taipei.

    PubMed

    Lo, S L; Chu, H A

    2006-01-01

    This research studied how the air pollutants of urban areas affect a neighboring reservoir and its water quality. Through the atmospheric dispersion process, air pollutants move from the Taipei metropolitan to the Feitsui reservoir and enter the water body through dry and wet depositions. ISCST3 (Industrial Source Complex Short Term Model), an air quality model, was used to simulate dispersion, dry deposition and wet deposition of the air pollutants. Then the nitrogen loadings to the Feitsui Reservoir were evaluated. The results indicate that wet deposition places a greater burden than dry deposition does on the water body. Wet and dry deposition of NH4+ together make up a rather large proportion of the total pollution. The ranged from 21.9 to 25.2%. Those of nitrate make up a smaller proportion, ranged from 2.0 to 2.3%. If we take indirect deposition into account and calculate the NO3- and NH4+ together, the proportion is 15.9-17.6%. PMID:16594353

  4. Anthropogenic 129I in the atmosphere: overview over major sources, transport processes and deposition pattern.

    PubMed

    Reithmeier, H; Lazarev, V; Rühm, W; Nolte, E

    2010-10-01

    Wet and, to a lesser extent, dry deposition of atmospheric (129)I are known to represent the dominating processes responsible for (129)I in continental environmental samples that are remote from (129)I sources and not directly influenced by any liquid (129)I release of nuclear installations. Up to now, however, little is known about the major emitters and the related global deposition pattern of (129)I. In this work an overview over major sources of (129)I is given, and hitherto unknown time-dependent releases from these were estimated. Total gaseous (129)I releases from the US and former Soviet reprocessing facilities Hanford, Savannah River, Mayak, Seversk and Zheleznogorsk were found to have been 0.53, 0.27, 1.05, 0.23 and 0.14TBq, respectively. These facilities were thus identified as major airborne (129)I emitters. The global deposition pattern due to the (129)I released, depending on geographic latitude and longitude, and on time was studied using a box model describing the global atmospheric transport and deposition of (129)I. The model predictions are compared to (129)I concentrations measured by means of Accelerator Mass Spectrometry (AMS) in water samples that were collected from various lakes in Asia, Africa, America and New Zealand, and to published values. As a result, both pattern and temporal evolution of (129)I deposition values measured in and calculated for different types of environmental samples are, in general, in good agreement. This supports our estimate on atmospheric (129)I releases and the considered substantial transport and deposition mechanisms in our model calculations. PMID:20692686

  5. Polybrominated diphenyl ethers at a solid waste incineration plant II: atmospheric deposition

    NASA Astrophysics Data System (ADS)

    ter Schure, Arnout F. H.; Agrell, Cecilia; Bokenstrand, Alma; Sveder, Jeanette; Larsson, Per; Zegers, Bart N.

    2004-09-01

    In the second of two papers, the atmospheric polybrominated diphenyl ethers (PBDE) deposition (wet and dry) at a municipal solid waste incineration (MSW) plant with electronics recycling is compared with that at an industrial urban reference site (URS) producing asphalt and concrete. Results of BDE209 and ΣPBDE excluding BDE209 as representatives of "new" vs. "old" PBDEs are presented. Volume weighted mean ΣPBDE and BDE209 concentrations at the MSW were 6.2 and 14.4 ng l-1, and at the URS were 2.5 and 14.1 ng l-1. Median ΣPBDE and BDE209 deposition fluxes were 21.3, 63.8 and 7.0, 14.7 ng m-2 day-1 at the MSW and URS, respectively. The concentrations in precipitation and the deposition fluxes were significantly higher at the MSW compared to the URS. Measured total washout- ratios (WT) were dependent on particle scavenging and the median WT for all congeners was 5.4×105. Median dry particle deposition velocities ranged from 0.4 to 49 cm s-1, depending on congener, showing that PBDEs are effectively removed from the atmosphere by particle deposition. PBDE fluxes increased at the reference site when winds were blowing from west-south-west, i.e. from the direction of the MSW. PBDE deposition and washout ratios were not influenced by temperature or rain volume, suggesting a constant emission from the MSW regardless of weather conditions. Together with the results of paper I (Agrell et al., 2004, Atmospheric Environment, this issue) we therefore suggest that treatment of waste, e.g. electronics recycling, is more a source of "old" PBDEs to the environment, whereas the rather similar BDE209 concentrations at the two urban sites are more a result of proximity to potential diffuse sources.

  6. Analysis of Atmospheric Nitrate Deposition in Lake Tahoe Using Multiple Oxygen Isotopes

    NASA Astrophysics Data System (ADS)

    McCabe, J. R.; Michalski, G. M.; Hernandez, L. P.; Thiemens, M. H.; Taylor, K.; Kendall, C.; Wankel, S. D.

    2002-12-01

    Lake Tahoe in the Sierra Nevada Mountain Range is world renown for its depth and water clarity bringing 2.2 million visitors per year resulting in annual revenue of \\1.6 billion from tourism. In past decades the lake has suffered from decreased water clarity (from 32 m plate depth to less than 20), which is believed to be largely the result of algae growth initiated by increased nutrient loading. Lake nutrients have also seen a shift from a nitrogen limited to a phosphorous limited system indicating a large increase in the flux of fixed nitrogen. Several sources of fixed nitrogen of have been suggested including surface runoff, septic tank seepage from ground water and deposition from the atmosphere. Bio-available nitrogen in the form of nitrate (NO_{3}$-) is a main component of this system. Recent studies have estimated that approximately 50% of the nitrogen input into the lake is of atmospheric origin (Allison et al. 2000). However, the impact and magnitude of atmospheric deposition is still one of the least understood aspects of the relationship between air and water quality in the Basin (TRPA Threshold Assessment 2002). The utility of stable isotopes as tracers of nitrate reservoirs has been shown in several studies (Bohlke et al. 1997, Kendall and McDonnell 1998, Durka et al. 1994). Stable nitrogen (δ15N) and oxygen (δ18O) isotopes have been implemented in a dual isotope approach to characterize the various nitrate sources to an ecosystem. While δ18O distinguishes between atmospheric and soil sources of nitrate, processes such as denitrification can enrich the residual nitrate in δ18O leaving a misleading atmospheric signature. The benefit of δ15N as a tracer for NO3- sources is the ability to differentiate natural soil, fertilizer, and animal or septic waste, which contain equivalent δ18O values. The recent implementation of multiple oxygen isotopes to measure Δ17O in nitrate has proven to be a more sensitive tracer of atmospheric deposition. The

  7. Atmospheric Deposition And MediterraneAN sea water productiviTy (Thales - ADAMANT) An overview

    NASA Astrophysics Data System (ADS)

    Christodoulaki, Sylvia; Petihakis, George; Triantafyllou, George; Pitta, Paraskevi; Papadimitriou, Vassileios; Tsiaras, Konstantinos; Mihalopoulos, Nikolaos; Kanakidou, Maria

    2015-04-01

    In the marine environment the salinity and biological pumps sequester atmospheric carbon dioxide. The biological pump is directly related to marine primary production which is controlled by nutrient availability mainly of iron, nitrogen and phosphorus. The Mediterranean Sea, especially the eastern basin is one of the most oligotrophic seas. The nitrogen (N) to phosphorus (P) ratio is unusually high, especially in the eastern basin (28:1) and primary production is limited by phosphorus availability. ADAMANT project contributes to new knowledge into how nutrients enter the marine environment through atmospheric deposition, how they are assimilated by organisms and how this influences carbon and nutrient fluxes. Experimental work has been combined with atmospheric and marine models. Important knowledge is obtained on nutrients deposition through mesocosm experiments on their uptake by the marine systems and their effects on the marine carbon cycle and food chain. Kinetic parameters of adsorption of acidic and organic volatile compounds in atmospheric samples of dust and marine salts are estimated in conjunction with solubility of N and P in mixtures contained in dust. Atmospheric and oceanographic models are coupled to create a system that is able to holistically simulate the effects of atmospheric deposition on the marine environment over time, beginning from the pre-industrial era until the future years (hind cast, present and forecast simulations). This research has been co-financed by the European Union (European Social Fund) and Greek national funds through the Operational Program "Education and Lifelong Learning" of the National Strategic Reference Framework - Research Funding Program: THALES, Investing in knowledge society through European Social Fund.

  8. Photocatalytic anatase titanium dioxide thin films deposition by an atmospheric pressure blown arc discharge

    NASA Astrophysics Data System (ADS)

    Boscher, Nicolas D.; Olivier, Sébastien; Maurau, Rémy; Bulou, Simon; Sindzingre, Thierry; Belmonte, Thierry; Choquet, Patrick

    2014-08-01

    TiO2 thin films are deposited by means of an atmospheric pressure blown arc discharge fed with nitrogen and titanium bis(acetylacetonate) diisopropoxide (TIPO) as precursor. Different power densities and distances between the plasma nozzle, the precursor injector and the substrate are investigated and different morphologies, compositions and crystallinities of the coatings are generated. The photocatalytic properties of the coatings, determined from the degradation of stearic acid shined by a 254 nm UV light, are shown to be strongly related to the film characteristic and therefore to the deposition parameters.

  9. Predicting wetland contamination from atmospheric deposition measurements of pesticides in the Canadian Prairie Pothole region

    NASA Astrophysics Data System (ADS)

    Messing, Paul G.; Farenhorst, Annemieke; Waite, Don T.; McQueen, D. A. Ross; Sproull, James F.; Humphries, David A.; Thompson, Laura L.

    2011-12-01

    Although it has been suggested that atmospheric deposition alone can result in detectable levels of pesticides in wetlands of the Pairie Pothole Region of Canada, this is the first field study to compare the masses of pesticides entering wetlands by atmospheric deposition with those concentrations of pesticides detected in the water-column of prairie wetlands. Weekly air and bulk deposition samples were collected from May 26th to Sept. 15th, 2008 at the Manitoba Zero Tillage Research Association (MZTRA) Farm, Brandon, Manitoba, with four on-site wetlands (approximate sizes 0.15-0.45 ha) monitored every second week. Twelve pesticides were detected in the air, with MCPA (one of the three pesticides applied on the farm in 2008 in addition to clopyralid and glyphosate), triallate, and γ-HCH being detected every week. Calculations were performed to predict wetland pesticide concentrations based on bulk deposits alone for those pesticides that had detectable concentrations in the bulk deposition samples (in order of the highest total seasonal deposition mass to the lowest): MCPA, glyphosate, 2,4-D, clopyralid, bromoxynil, atrazine, dicamba, metolachlor, and mecoprop. The estimated concentrations were closest to actual concentrations for MCPA (Pearson correlation coefficient's = 0.91 to 0.98; p-values < 0.001) and predictions were also reasonable for a range of other herbicides, but a source other than atmospheric deposition was clearly relevant to detections of clopyralid in the wetland water-column. Although the types and levels of pesticides detected in the wetlands of the current study suggest that regional pesticide applications can contribute to pesticide surface water contamination following atmospheric transport and deposition, the greater frequency and concentrations of clopyralid, MCPA, and glyphosate detections in wetlands confirm that on-farm pesticide applications have a greater impact on on-site water quality. Beneficial management practices that reduce

  10. Long-term atmospheric deposition of nitrogen, phosphorus and sulfate in a large oligotrophic lake

    PubMed Central

    Craft, James A.; Stanford, Jack A.

    2015-01-01

    We documented significantly increasing trends in atmospheric loading of ammonium (NH4) and nitrate/nitrite (NO2/3) and decreasing trends in total phosphorus (P) and sulfate (SO4) to Flathead Lake, Montana, from 1985 to 2004. Atmospheric loading of NO2/3 and NH4 increased by 48 and 198% and total P and SO4 decreased by 135 and 39%. The molar ratio of TN:TP also increased significantly. Severe air inversions occurred periodically year-round and increased the potential for substantial nutrient loading from even small local sources. Correlations between our loading data and various measures of air quality in the basin (e.g., particulate matter <10 µm in size, aerosol fine soil mass, aerosol nutrient species, aerosol index, hectares burned) suggest that dust and smoke are important sources. Ammonium was the primary form of N in atmospheric deposition, whereas NO3 was the primary N form in tributary inputs. Atmospheric loading of NH4 to Flathead Lake averaged 44% of the total load and on some years exceeded tributary loading. Primary productivity in the lake is colimited by both N and P most of the year; and in years of high atmospheric loading of inorganic N, deposition may account for up to 6.9% of carbon converted to biomass. PMID:25802810

  11. Long-term atmospheric deposition of nitrogen, phosphorus and sulfate in a large oligotrophic lake.

    PubMed

    Ellis, Bonnie K; Craft, James A; Stanford, Jack A

    2015-01-01

    We documented significantly increasing trends in atmospheric loading of ammonium (NH4) and nitrate/nitrite (NO2/3) and decreasing trends in total phosphorus (P) and sulfate (SO4) to Flathead Lake, Montana, from 1985 to 2004. Atmospheric loading of NO2/3 and NH4 increased by 48 and 198% and total P and SO4 decreased by 135 and 39%. The molar ratio of TN:TP also increased significantly. Severe air inversions occurred periodically year-round and increased the potential for substantial nutrient loading from even small local sources. Correlations between our loading data and various measures of air quality in the basin (e.g., particulate matter <10 µm in size, aerosol fine soil mass, aerosol nutrient species, aerosol index, hectares burned) suggest that dust and smoke are important sources. Ammonium was the primary form of N in atmospheric deposition, whereas NO3 was the primary N form in tributary inputs. Atmospheric loading of NH4 to Flathead Lake averaged 44% of the total load and on some years exceeded tributary loading. Primary productivity in the lake is colimited by both N and P most of the year; and in years of high atmospheric loading of inorganic N, deposition may account for up to 6.9% of carbon converted to biomass. PMID:25802810

  12. Characteristics Of Atmospheric Dry Deposition Of Metals To The Region Of Lake Asan And Sapgyo, Korea

    NASA Astrophysics Data System (ADS)

    Han, J.; Shin, H.; Lee, M.; Lim, Y.; Seo, M.; Jung, I.

    2008-12-01

    Environment includes a multi-media such as air, surface water, soil, underground water and ecosystem. Some pollutants transfer among a multi-media, posing serious threat to humans, animals and plants. Pollutants released into the environment remain for long times and transport long distances while going through physical and chemical interactions such as transports between multi-media ; air, water and soil, deposition, and absorption and release from organisms. This study assessed the amount of heavy metals transferred from air to water and soil using dry deposition plate and water surface sampler during spring (June 13 ~ 21, 2007) and winter (October 23 ~ 30 in 2007) at 9 locations including Dangjin, Pyeongtaek and Asan. Micro-Orifice Uniform Deposit Impactor, MOUDI was used to confirm the size distribution. The measured heavy metal deposition flux was compared with the expectation obtained with deposition model. In addition, amount of heavy metal deposition at Asan and Sapgyo lakes were evaluated to verify the water pollution state driven by atmospheric deposition. Atmospheric dry deposition flux of metals are 133.92 microgram m-2 day-1, 44.01 microgram m-2 day-1, 0.915 microgram m-2 day-1, and 0.175 microgram m-2 day-1 during spring, and 72.86 microgram m-2 day- 1, 88.14 microgram m-2 day-1, 0.991 microgram m-2 day-1, and 0.189 microgram m-2 day-1 during fall, for lead, nickel, arsenic, and cadmium, respectively. It is required to re- calculation the dry deposition flux by land use type due to possibility of underestimating the flux in case of using grease surrogate surface having low surface roughness. The cadmium, lead, and arsenic size distribution was mono-modal with the peaks in the 0.65 ~ 1.1 micrometer size range in the fine mode showing sharp peak in the condensation submode especially for cadmium and lead because of effect of primary emission. The nickel size distribution was bimodal, a typical size distribution for an urban atmosphere, showing sharp

  13. Nitrogen Accumulation and Partitioning in High Arctic Tundra from Extreme Atmospheric N Deposition Events

    NASA Astrophysics Data System (ADS)

    Phoenix, G. K.; Osborn, A.; Blaud, A.; Press, M. C.; Choudhary, S.

    2013-12-01

    Arctic ecosystems are threatened by pollution from extreme atmospheric nitrogen (N) deposition events. These events occur from the long-range transport of reactive N from pollution sources at lower latitudes and can deposit up to 80% of the annual N deposition in just a few days. To date, the fate and impacts of these extreme pollutant events has remained unknown. Using a field simulation study, we undertook the first assessment of the fate of acutely deposited N on arctic tundra. Extreme N deposition events were simulated on field plots at Ny-Ålesund, Svalbard (79oN) at rates of 0, 0.04, 0.4 and 1.2 g N m-2 yr-1 applied as NH4NO3 solution over 4 days, with 15N tracers used in the second year to quantify the fate of the deposited N in the plant, soil, microbial and leachate pools. Separate applications of 15NO3- and 15NH4+ were also made to determine the importance of N form in the fate of N. Recovery of the 15N tracer at the end of the first growing season approached 100% of the 15N applied irrespective of treatment level, demonstrating the considerable capacity of High Arctic tundra to capture pollutant N from extreme deposition events. Most incorporation of the 15N was found in bryophytes, followed by the dominant vascular plant (Salix polaris) and the microbial biomass of the soil organic layer. Total recovery remained high in the second growing season (average of 90%), indicating highly conservative N retention. Between the two N forms, recovery of 15NO3- and 15NH4+ were equal in the non-vascular plants, whereas in the vascular plants (particularly Salix polaris) recovery of 15NO3- was four times higher than of 15NH4+. Overall, these findings show that High Arctic tundra has considerable capacity to capture and retain the pollutant N deposited in acute extreme deposition events. Given they can represent much of the annual N deposition, extreme deposition events may be more important than increased chronic N deposition as a pollution source. Furthermore

  14. Pacific Northwest Laboratory annual report for 1984 to the DOE Office of Energy Research. Part 3. Atmospheric sciences

    SciTech Connect

    Elderkin, C.E.

    1985-02-01

    The goals of atmospheric research at Pacific Northwest Laboratory (PNL) are to assess, describe, and predict the nature and fate of atmospheric contaminants and to study the impacts of contaminants on local, regional, and global climates. The contaminants being investigated are those resulting from the development and use of conventional resources (coal, gas, oil, and nuclear power) as well as alternative energy sources. The description of the research is organized into 3 sections: (1) Atmospheric Studies in Complex Terrain (ASCOT); (2) Boundary Layer Meteorology; and (3) Dispersion, Deposition, and Resuspension of Atmospheric Contaminants. Separate analytics have been done for each of the sections and are indexed and contained in the EDB. (MDF)

  15. Atmospheric dry deposition of persistent organic pollutants to the Atlantic and inferences for the global oceans.

    PubMed

    Jurado, Elena; Jaward, Foday M; Lohmann, Rainer; Jones, Kevin C; Simó, Rafel; Dachs, Jordi

    2004-11-01

    Atmospheric deposition to the oceans is a key process affecting the global dynamics and sinks of persistent organic pollutants (POPs). A new methodology that combines aerosol remote sensing measurements with measured POP aerosol-phase concentrations is presented to derive dry particulate depositional fluxes of POPs to the oceans. These fluxes are compared with those due to diffusive air-water exchange. For all polychlorinated biphenyl (PCB) congeners and lower chlorinated dibenzo-p-dioxins and furans (PCDD/Fs), air-water exchange dominates the dry deposition mechanism. However, this tendency reverses in some areas, such as in marine aerosol influenced areas and dust outflow regions, consistent with the important variability encountered for the depositional fluxes. Seasonal variability is mainly found in mid-high latitudes, due to the important influence of wind speed enhancing dry deposition fluxes and temperature as a driver of the gas-particle partitioning of POPs. The average dry aerosol deposition flux of sigmaPCBs and sigmaPCDD/Fs to the Atlantic Ocean is calculated to be in the order of 66 ng m(-2) yr(-1) and 9 ng m(-2)yr(-1) respectively. The total dry aerosol deposition of sigmaPCBs and sigmaPCDD/Fs to the Atlantic Ocean is estimated to be 2200 kg yr(-1) and 500 kg yr(-1), respectively, while the net air-water exchange is higher, 22000 kg sigmaPCBs yr(-1) for PCBs and 1300 kg sigmaPCDD/Fs yr(-1). Furthermore, it is suggested that marine aerosol plays an important role in scavenging atmospheric contaminants. PMID:15575265

  16. Estimating contribution of precipitation scavenging of atmospheric particulate mercury to mercury wet deposition in Japan

    NASA Astrophysics Data System (ADS)

    Sakata, Masahiro; Asakura, Kazuo

    Mercury wet deposition is dependent on both the scavenging of divalent reactive gaseous mercury (RGM) and atmospheric particulate mercury (Hg(p)) by precipitation. Estimating the contribution of precipitation scavenging of RGM and Hg(p) is important for better understanding the causes of the regional and seasonal variations in mercury wet deposition. In this study, the contribution of Hg(p) scavenging was estimated on the basis of the scavenging ratios of other trace elements (i.e., Cd, Cu, Mn, Ni, Pb and V) existing entirely in particulate form. Their wet deposition fluxes and concentrations in air, which were measured concurrently from April 2004 to March 2005 at 10 sites in Japan, were used in this estimation. The monthly wet deposition flux of mercury at each site correlated with the amount of monthly precipitation, whereas the Hg(p) concentrations in air tended to decrease during summer. There was a significant correlation ( P<0.001) among the calculated monthly average scavenging ratios of trace elements, and the values in each month at each site were similar. Therefore, it is assumed the monthly scavenging ratio of Hg(p) is equivalent to the mean value of other trace elements. Using this scavenging ratio ( W), the wet deposition flux ( F) due to Hg(p) scavenging in each month was calculated by F= WKP, where K and P are the Hg(p) concentration and amount of precipitation, respectively. Relatively large fluxes due to Hg(p) scavenging were observed at a highly industrial site and at sites on the Japan Sea coast, which are strongly affected by the local sources and the long-range transport from the Asian continent, respectively. However, on average, at the 10 sites, the contribution of Hg(p) scavenging to the annual mercury deposition flux was 26%, suggesting that mercury wet deposition in Japan is dominated by RGM scavenging. This RGM should originate mainly from the in situ oxidation of Hg 0 in the atmosphere.

  17. Atmospheric N Deposition Increases Bacterial Laccase-Like Multicopper Oxidases: Implications for Organic Matter Decay

    PubMed Central

    Zak, Donald R.

    2014-01-01

    Anthropogenic release of biologically available nitrogen (N) has increased dramatically over the last 150 years, which can alter the processes controlling carbon (C) storage in terrestrial ecosystems. In a northern hardwood forest ecosystem located in Michigan in the United States, nearly 20 years of experimentally increased atmospheric N deposition has reduced forest floor decay and increased soil C storage. This change occurred concomitantly with compositional changes in Basidiomycete fungi and in Actinobacteria, as well as the downregulation of fungal lignocelluloytic genes. Recently, laccase-like multicopper oxidases (LMCOs) have been discovered among bacteria which can oxidize β-O-4 linkages in phenolic compounds (e.g., lignin and humic compounds), resulting in the production of dissolved organic carbon (DOC). Here, we examined how nearly 2 decades of experimental N deposition has affected the abundance and composition of saprotrophic bacteria possessing LMCO genes. In our experiment, LMCO genes were more abundant in the forest floor under experimental N deposition whereas the abundances of bacteria and fungi were unchanged. Experimental N deposition also led to less-diverse, significantly altered bacterial and LMCO gene assemblages, with taxa implicated in organic matter decay (i.e., Actinobacteria, Proteobacteria) accounting for the majority of compositional changes. These results suggest that experimental N deposition favors bacteria in the forest floor that harbor the LMCO gene and represents a plausible mechanism by which anthropogenic N deposition has reduced decomposition, increased soil C storage, and accelerated phenolic DOC production in our field experiment. Our observations suggest that future rates of atmospheric N deposition could fundamentally alter the physiological potential of soil microbial communities. PMID:24837374

  18. Subalpine grassland carbon balance during 7 years of increased atmospheric N deposition

    NASA Astrophysics Data System (ADS)

    Volk, Matthias; Enderle, Jan; Bassin, Seraina

    2016-07-01

    Air pollution agents interact when affecting biological sinks for atmospheric CO2, e.g., the soil organic carbon (SOC) content of grassland ecosystems. Factors favoring plant productivity, like atmospheric N deposition, are usually considered to favor SOC storage. In a 7-year experiment in subalpine grassland under N- and O3-deposition treatment, we examined C fluxes and pools. Total N deposition was 4, 9, 14, 29 and 54 kg N ha-1 yr-1 (N4, N9, etc.); annual mean phytotoxic O3 dose was 49, 65 and 89 mmol m-2 projected leaf area. We hypothesized that between years SOC of this mature ecosystem would not change in control treatments and that effects of air pollutants are similar for plant yield, net ecosystem productivity (NEP) and SOC content, leading to SOC content increasing with N deposition. Cumulative plant yield showed a significant N and N × N effect (+38 % in N54) but no O3 effect. In the control treatment SOC increased significantly by 9 % in 7 years. Cumulative NEP did show a strong, hump-shaped response pattern to N deposition with a +62 % increase in N14 and only +39 % increase in N54 (N effect statistically not significant, N × N interaction not testable). SOC had a similar but not significant response to N, with highest C gains at intermediate N deposition rates, suggesting a unimodal response with a marginal (P = 0.09) N × N interaction. We assume the strong, pollutant-independent soil C sink developed as a consequence of the management change from grazing to cutting. The non-parallel response of SOC and NEP compared to plant yield under N deposition is likely the result of increased respiratory SOC losses, following mitigated microbial N-limitation or priming effects, and a shift in plant C allocation leading to smaller C input from roots.

  19. Resuspension studies in the Marshall Islands

    SciTech Connect

    Shinn, J.H.; Homan, D.N.; Robison, W.L.

    1997-07-01

    The contribution of inhalation exposure to the total dose for residents of the Marshall Islands was monitored at occasions of opportunity on several islands in the Bikini and Enewetak Atolls. To determine the long-term potential for inhalation exposure, and to understand the mechanisms of redistribution and personal exposure, additional investigations were undertaken on Bikini Island under modified and controlled conditions. Experiments were conducted to provide key parameters for the assessment of inhalation exposure from plutonium-contaminated dust aerosols: characterization of the contribution of plutonium in soil-borne aerosols as compared to sea spray and organic aerosols, determination of plutonium resuspension rates as measured by the meteorological flux-gradient method during extreme conditions of a bare-soil vs. a stabilized surface, determination of the approximate individual exposures to resuspended plutonium by traffic, and studies of exposures to individuals in different occupational environments simulated by personal air sampling of workers assigned to a variety of tasks. Enhancement factors (defined as ratios of the plutonium-activity), of suspended aerosols relative to the plutonium-activity of the soil were determined to be less than 1 (typically 0.4 to 0.7) in the undisturbed, vegetated areas, but greater than 1 (as high as 3) for the case studies of disturbed bare soil, roadside travel, and for occupational duties in fields and in and around houses. 12 refs., 5 figs., 8 tabs.

  20. Nitrogen accumulation and partitioning in a High Arctic tundra ecosystem from extreme atmospheric N deposition events.

    PubMed

    Choudhary, Sonal; Blaud, Aimeric; Osborn, A Mark; Press, Malcolm C; Phoenix, Gareth K

    2016-06-01

    Arctic ecosystems are threatened by pollution from recently detected extreme atmospheric nitrogen (N) deposition events in which up to 90% of the annual N deposition can occur in just a few days. We undertook the first assessment of the fate of N from extreme deposition in High Arctic tundra and are presenting the results from the whole ecosystem (15)N labelling experiment. In 2010, we simulated N depositions at rates of 0, 0.04, 0.4 and 1.2 g Nm(-2)yr(-1), applied as (15)NH4(15)NO3 in Svalbard (79(°)N), during the summer. Separate applications of (15)NO3(-) and (15)NH4(+) were also made to determine the importance of N form in their retention. More than 95% of the total (15)N applied was recovered after one growing season (~90% after two), demonstrating a considerable capacity of Arctic tundra to retain N from these deposition events. Important sinks for the deposited N, regardless of its application rate or form, were non-vascular plants>vascular plants>organic soil>litter>mineral soil, suggesting that non-vascular plants could be the primary component of this ecosystem to undergo measurable changes due to N enrichment from extreme deposition events. Substantial retention of N by soil microbial biomass (70% and 39% of (15)N in organic and mineral horizon, respectively) during the initial partitioning demonstrated their capacity to act as effective buffers for N leaching. Between the two N forms, vascular plants (Salix polaris) in particular showed difference in their N recovery, incorporating four times greater (15)NO3(-) than (15)NH4(+), suggesting deposition rich in nitrate will impact them more. Overall, these findings show that despite the deposition rates being extreme in statistical terms, biologically they do not exceed the capacity of tundra to sequester pollutant N during the growing season. Therefore, current and future extreme events may represent a major source of eutrophication. PMID:26956177

  1. Flow separation and resuspension beneath shoaling nonlinear internal waves

    NASA Astrophysics Data System (ADS)

    Boegman, Leon; Ivey, Gregory N.

    2009-02-01

    Laboratory observations are presented showing the structure and dynamics of the turbulent bottom boundary layer beneath nonlinear internal waves (NLIWs) of depression shoaling upon sloping topography. The adverse pressure gradient beneath the shoaling waves causes the rear face to steepen, flow separation to occur, and wave-induced near-bottom vortices to suspend bed material. The resuspension is directly attributed to the near-bed viscous stress and to near-bed patches of elevated positive Reynolds stress generated by the vortical structures. These results are consistent with published field observations of resuspension events beneath shoaling NLIWs. Elevated near-bed viscous stresses are found throughout the domain at locations that are not correlated to the resuspension events. Near-bed viscous stress is thus required for incipient sediment motion but is not necessarily a precursor for resuspension. Resuspension is dependent on the vertical velocity field associated with positive Reynolds stress and is also found to occur where the mean (wave-averaged) vertical velocity is directed away from the bed. The results are interpreted by analogy to the eddy-stress and turbulent bursting resuspension models developed for turbulent channel flows.

  2. Variation in mineral content of red maple sap across an atmospheric deposition gradient

    SciTech Connect

    McCormick, L.H.

    1997-11-01

    Xylem sap was collected from red maple (Acer rubrum L.) trees during the spring of 1988 and 1989 at seven forest sites along an atmospheric deposition gradient in north central Pennsylvania and analyzed for pH and twelve mineral constituents. The objectives of the study were to examine the sources and patterns of variation in red maple sap chemistry across an atmospheric deposition gradient and to assess the feasibility of using sap analysis as an indicator of nutrient bioavailability. For most sap constituents, there was considerable spatial and temporal variation in concentration. Sources of variation included within and between site variation, date, and year of collection. The nature and extent of variation varied for different constituents. Site differences were similar in 1988 and 1989 for most sap constituents and for some constituents corresponded with differences in soil levels.

  3. Lead isotopes tracing weathering and atmospheric deposition in a small volcanic catchment

    NASA Astrophysics Data System (ADS)

    Négrel, Philippe; Petelet-Giraud, Emmanuelle; Guerrot, Catherine; Millot, Romain

    2015-09-01

    Lead isotopes were studied in soil and sediments of the small volcanic catchment in the Massif Central (France), a large area of Tertiary to Recent continental alkaline volcanism. The comparison of Pb and K (normalized to Zr) shows a linear evolution of weathering processes, whereby lead enrichment from atmospheric deposition is a major contributor explaining the deviation of several points from this line. A box model simulates the lead evolution in sediments from soil production on the hillslopes due to bedrock weathering and from anthropogenic input through atmospheric deposition and constrains the dynamics of sediment transfer. Lead isotope ratios decrease from bedrock to sediment and soil without any clear relationship when compared to lead contents. Pb isotopic compositions showed that most of the lead budget in sediment and soil results from bedrock weathering with influence of gasoline-additive-lead and past mining activities derived inputs, but no lead input from agricultural activity.

  4. Sintering of Glass in Hydrous Atmospheres and its Implications for Welding of Volcanic Deposits

    NASA Astrophysics Data System (ADS)

    von Aulock, F. W.; Wadsworth, F. B.; Lavallée, Y.; Vasseur, J.

    2014-12-01

    Volcanic ash sintering can occur during hot deposition or upon reheating, and recently published models have improved our understanding of viscous sintering timescales at magmatic temperatures. However, in most volcanic environments, water is present either from meteoric or magmatic sources. Water significantly lowers the viscosity of liquids and therefore should alter the onset temperature and timescales of sintering. The diffusion of water in melts and glasses at low (sub-liquidus) temperatures and pressures, and the partitioning between water vapor and dissolved water species are poorly understood. We investigate the impact of a water rich Ar -atmosphere on viscous sintering at temperatures close to the glass transition. Synthetic near-spherical soda-lime silica glass beads with a well-constrained size of about 10-350μm (produced by Spheriglass) were heated in simultaneous thermal analyses of both differential scanning calorimetry and thermogravimetry. Glass transition temperature onset and mass stayed consistent under argon atmosphere during successive heating cycles at a rate of 10 °C.min-1. Contrastingly, preliminary results show that, when heated, closely packed in a water-argon atmosphere (1) there is a measurable water uptake during timescales as short as 2 hours, and (2) sintering is more efficient and densification takes place at lower temperatures and/or within shorter timescales. Sintering of volcanic materials reduces both porosity and permeability of volcanic products. The process of sintering is, however, limited by quenching of the material shortly after eruption. External water present during deposition could allow welding of pyroclastic deposits at conditions and timescales otherwise not achievable from the deposited pyroclasts alone.. Viscous sintering in a water-rich atmosphere may enhance resorption and encourage the formation of vesicle-free obsidian.

  5. Recent atmospheric dust deposition in an ombrotrophic peat bog in Great Hinggan Mountain, Northeast China.

    PubMed

    Bao, Kunshan; Xing, Wei; Yu, Xiaofei; Zhao, Hongmei; McLaughlin, Neil; Lu, Xianguo; Wang, Guoping

    2012-08-01

    Recent deposition of atmospheric soil dust (ASD) was studied using (210)Pb-dated Sphagnum-derived peat sequences from Great Hinggan Mountain in northeast China. Physicochemical indices of peat including dry bulk density, water content, ash content, total organic carbon and mass magnetic susceptibility were measured. Acid-insoluble concentration of lithogenic metals (Al, Ca, Fe, Mn, V and Ti) were measured using ICP-AES. The basic physicochemical properties were used to assess the peat trophic status and indicated that the sections above 45-60 cm are rain-fed peat. A continuous record of ASD fluxes over the past 150 years was reconstructed based on the geochemical data obtained from the ombrotrophic zone, and the average input rate of ASD is 13.4-68.1 g m(-2) year(-1). The source of soil dust deposited in peat was dominated by the long-range transport of mineral aerosol from the drylands in north China and Mongolia. The temporal variation of ASD fluxes in the last 60 years coincides well with the meteorological records of dust storm frequency during 1954-2002 in north China. This suggests that the reconstructed sequence of atmospheric dust deposition is reliable and we can look back in time at the dust evolution before 1949. Dust storm events were observed occasionally in the late Qing dynasty, and their frequency and intensity were smaller than dust weather occurring in recent times. Four peaks of ASD fluxes were distinguished and correlated with the historical events at that time. This study presents the first atmospheric soil dust data in peat records in northeast China, and complements a global database of peat bog archives of atmospheric deposition. The results reflect the patterns of local environmental change over the past century in north China and will be helpful in formulating policies to achieve sustainable and healthy development. PMID:22664536

  6. The anthropogenic atmospheric elements fraction: A new interpretation of elemental deposits on tree barks

    NASA Astrophysics Data System (ADS)

    Catinon, Mickaël; Ayrault, Sophie; Clocchiatti, Roberto; Boudouma, Omar; Asta, Juliette; Tissut, Michel; Ravanel, Patrick

    The superficial deposit on the bark surface of several trees (mainly Fraxinus excelsior L.) was sampled in the experimental station of the university campus in Grenoble (France). Its composition was studied by scanning electron microscopy-energy dispersive X-ray emission (SEM-EDX) and, after digestion, by inductively coupled plasma-mass spectrometry (ICP-MS). The deposit was composed of 81.3% ± 7.4 organic matter, 9.4% ± 4.9 of geogenic minerals issued from the atmosphere (atmospheric geogenic fraction: AGF) and 9.3% ± 2.7 of a mixture of elements which was called anthropogenic atmospheric elements fraction (AAEF). The SEM-EDX analysis showed the presence of particles of geogenic compounds such as different types of silicates, phosphates, carbonates, sulphates, oxides and also particles of metals such as iron or of alloys of Fe-Zn, Fe-Ni, Ni-Cr and Ca sulphates or phosphates. Typical spheres of "fly ashes" composed of pure iron or Al-silicates were detected. Using the SEM-EDX analysis of the deposit and the average local soil composition, an empiric formula for the AGF (without polluting elements) was chosen, which presented a clear analogy with the global formula of the upper continental crust. In the same way, a formula for the pure organic matter fraction was chosen. Withdrawing the elements corresponding to these two fractions allows a tentative estimation of the content of the AAEF which was supposed to better represent the elemental anthropogenic contamination issued from the atmosphere. In the station, most of Sb, Cd, Sn, Pb, Cu, V and Zn were found in the AAEF. This AAEF composition was compared to that of the deposit in a highway tunnel where Pb and Cu were at a very high level. The meaning and the limits of the AAEF concept were critically discussed.

  7. Detection of Atmospheric Water Deposits in Porous Media Using the TDR Technique

    PubMed Central

    Nakonieczna, Anna; Kafarski, Marcin; Wilczek, Andrzej; Szypłowska, Agnieszka; Janik, Grzegorz; Albert, Małgorzata; Skierucha, Wojciech

    2015-01-01

    Investigating the intensity of atmospheric water deposition and its diurnal distribution is essential from the ecological perspective, especially regarding dry geographic regions. It is also important in the context of monitoring the amount of moisture present within building materials in order to protect them from excessive humidity. The objective of this study was to test a constructed sensor and determine whether it could detect and track changes in the intensity of atmospheric water deposition. An operating principle of the device is based on the time-domain reflectometry technique. Two sensors of different plate volumes were manufactured. They were calibrated at several temperatures and tested during field measurements. The calibration turned out to be temperature independent. The outdoor measurements indicated that the upper limits of the measurement ranges of the sensors depended on the volumes of the plates and were equal to 1.2 and 2.8 mm H2O. The respective sensitivities were equal to 3.2 × 10−3 and 7.5 × 10−3 g·ps−1. The conducted experiments showed that the construction of the designed device and the time-domain reflectometry technique were appropriate for detecting and tracing the dynamics of atmospheric water deposition. The obtained outcomes were also collated with the readings taken in an actual soil sample. For this purpose, an open container sensor, which allows investigating atmospheric water deposition in soil, was manufactured. It turned out that the readings taken by the porous ceramic plate sensor reflected the outcomes of the measurements performed in a soil sample. PMID:25871717

  8. Characterisation of atmospheric deposited particles during a dust storm in urban areas of Eastern Australia.

    PubMed

    Gunawardena, Janaka; Ziyath, Abdul M; Bostrom, Thor E; Bekessy, Lambert K; Ayoko, Godwin A; Egodawatta, Prasanna; Goonetilleke, Ashantha

    2013-09-01

    The characteristics of dust particles deposited during the 2009 dust storm in the Gold Coast and Brisbane regions of Australia are discussed in this paper. The study outcomes provide important knowledge in relation to the potential impacts of dust storm related pollution on ecosystem health in the context that the frequency of dust storms is predicted to increase due to anthropogenic desert surface modifications and climate change impacts. The investigated dust storm contributed a large fraction of fine particles to the environment with an increased amount of total suspended solids, compared to dry deposition under ambient conditions. Although the dust storm passed over forested areas, the organic carbon content in the dust was relatively low. The primary metals present in the dust storm deposition were aluminium, iron and manganese, which are common soil minerals in Australia. The dust storm deposition did not contain significant loads of nickel, cadmium, copper and lead, which are commonly present in the urban environment. Furthermore, the comparison between the ambient and dust storm chromium and zinc loads suggested that these metals were contributed to the dust storm by local anthropogenic sources. The potential ecosystem health impacts of the 2009 dust storm include, increased fine solids deposition on ground surfaces resulting in an enhanced capacity to adsorb toxic pollutants as well as increased aluminium, iron and manganese loads. In contrast, the ecosystem health impacts related to organic carbon and other metals from dust storm atmospheric deposition are not considered to be significant. PMID:23712117

  9. Impact of atmospheric deposition on algal growth in Lake Tahoe, CA

    NASA Astrophysics Data System (ADS)

    Paytan, A.; Mackey, K. R.; Jiang, Y.; Liston, A.; Allen, B.; Schladow, S. G.

    2010-12-01

    Lake Tahoe’s clarity has been declining over the past decades and it is important to understand the causes and consequences of this decline. Lake Tahoe’s clarity is determined by fine sediment particles and by nutrients. Nutrients affect lake clarity by promoting algae growth. Indeed primary productivity, the rate at which algae produce biomass through photosynthesis, has been increasing since 1959. Offshore, algae make the water greenish and less clear. The two nutrients that most affect algal growth in this system are nitrogen and phosphorus. Atmospheric deposition is an important source of nutrients to the lake contributing 55% of the nitrogen load and 15% of the phosphate load (State of the Lake Report - http://terc.ucdavis.edu/stateofthelake/StateOfTheLake2009.pdf). To evaluate if and how atmospheric deposition impacts phytoplankton growth and abundance we have preformed bioassay experiments with inorganic nutrient and aerosol additions during the summer of 2010. Our results indicate that, as expected for this season, nitrogen or combined nitrogen and phosphate induce growth. Our aerosol additions also induced growth and suggest that nutrients originating from aerosols are bio-available and can stimulate phytoplankton production. Atmospheric deposition can therefore affect lake clarity and should be monitored to ensure that the state of the lake does not deteriorate further.

  10. Impact of atmospheric wet deposition on phytoplankton community structure in the South China Sea

    NASA Astrophysics Data System (ADS)

    Cui, Dong-Yang; Wang, Jiang-Tao; Tan, Li-Ju; Dong, Ze-Yi

    2016-05-01

    The South China Sea (SCS), which is the largest marginal sea in East Asia, plays a significant role in regional climate change. However, research on the phytoplankton community structure (PCS) response to atmospheric wet deposition remains inadequate. In this study, field incubation experiments were performed to survey the impact of atmospheric wet deposition on the PCS in the SCS in December 2013. Results indicate that the mean dissolved inorganic nitrogen/dissolved inorganic phosphorous (DIN/DIP) ratio in rainwater was 136, which was higher than that in seawater. Under low initial nutrient concentrations, rainwater inputs not only significantly increased total chlorophyll a (Chl a) concentrations but also potentially altered the PCS. The total Chl a concentration increased 1.7-, 1.9-, and 1.6-fold; microphytoplankton increased 2.6-, 3.2-, and 1.7-fold with respect to their initial values in the 5%, 10% addition, and 10% addition (filtered) treatment samples, respectively. Finally, microphytoplankton contributed 61% to the total Chl a concentration in 10% addition treatment samples. Differences in the nutrients induced by atmospheric wet deposition resulted in a shift in the advantage from picophytoplankton to microphytoplankton. Diatoms became the predominant species, accounting for 55% of the total abundance after rainwater addition.

  11. CAN Canopy Addition of Nitrogen Better Illustrate the Effect of Atmospheric Nitrogen Deposition on Forest Ecosystem?

    NASA Astrophysics Data System (ADS)

    Zhang, Wei; Shen, Weijun; Zhu, Shidan; Wan, Shiqiang; Luo, Yiqi; Yan, Junhua; Wang, Keya; Liu, Lei; Dai, Huitang; Li, Peixue; Dai, Keyuan; Zhang, Weixin; Liu, Zhanfeng; Wang, Faming; Kuang, Yuanwen; Li, Zhian; Lin, Yongbiao; Rao, Xingquan; Li, Jiong; Zou, Bi; Cai, Xian; Mo, Jiangming; Zhao, Ping; Ye, Qing; Huang, Jianguo; Fu, Shenglei

    2015-06-01

    Increasing atmospheric nitrogen (N) deposition could profoundly impact community structure and ecosystem functions in forests. However, conventional experiments with understory addition of N (UAN) largely neglect canopy-associated biota and processes and therefore may not realistically simulate atmospheric N deposition to generate reliable impacts on forest ecosystems. Here we, for the first time, designed a novel experiment with canopy addition of N (CAN) vs. UAN and reviewed the merits and pitfalls of the two approaches. The following hypotheses will be tested: i) UAN overestimates the N addition effects on understory and soil processes but underestimates those on canopy-associated biota and processes, ii) with low-level N addition, CAN favors canopy tree species and canopy-dwelling biota and promotes the detritus food web, and iii) with high-level N addition, CAN suppresses canopy tree species and other biota and favors rhizosphere food web. As a long-term comprehensive program, this experiment will provide opportunities for multidisciplinary collaborations, including biogeochemistry, microbiology, zoology, and plant science to examine forest ecosystem responses to atmospheric N deposition.

  12. CAN Canopy Addition of Nitrogen Better Illustrate the Effect of Atmospheric Nitrogen Deposition on Forest Ecosystem?

    PubMed Central

    Zhang, Wei; Shen, Weijun; Zhu, Shidan; Wan, Shiqiang; Luo, Yiqi; Yan, Junhua; Wang, Keya; Liu, Lei; Dai, Huitang; Li, Peixue; Dai, Keyuan; Zhang, Weixin; Liu, Zhanfeng; Wang, Faming; Kuang, Yuanwen; Li, Zhian; Lin, Yongbiao; Rao, Xingquan; Li, Jiong; Zou, Bi; Cai, Xian; Mo, Jiangming; Zhao, Ping; Ye, Qing; Huang, Jianguo; Fu, Shenglei

    2015-01-01

    Increasing atmospheric nitrogen (N) deposition could profoundly impact community structure and ecosystem functions in forests. However, conventional experiments with understory addition of N (UAN) largely neglect canopy-associated biota and processes and therefore may not realistically simulate atmospheric N deposition to generate reliable impacts on forest ecosystems. Here we, for the first time, designed a novel experiment with canopy addition of N (CAN) vs. UAN and reviewed the merits and pitfalls of the two approaches. The following hypotheses will be tested: i) UAN overestimates the N addition effects on understory and soil processes but underestimates those on canopy-associated biota and processes, ii) with low-level N addition, CAN favors canopy tree species and canopy-dwelling biota and promotes the detritus food web, and iii) with high-level N addition, CAN suppresses canopy tree species and other biota and favors rhizosphere food web. As a long-term comprehensive program, this experiment will provide opportunities for multidisciplinary collaborations, including biogeochemistry, microbiology, zoology, and plant science to examine forest ecosystem responses to atmospheric N deposition. PMID:26059183

  13. Atmospheric Nitrogen Deposition to the Oceans: Observation- and Model-Based Estimates

    NASA Astrophysics Data System (ADS)

    Baker, Alex

    2016-04-01

    The reactive nitrogen (Nr) burden of the atmosphere has been increased by a factor of 3-4 by anthropogenic activity since the Industrial Revolution. This has led to large increases in the deposition of nitrate and ammonium to the surface waters of the open ocean, particularly downwind of major human population centres, such as those in North America, Europe and Southeast Asia. In oligotrophic waters, this deposition has the potential to significantly impact marine productivity and the global carbon cycle. Global-scale understanding of N deposition to the oceans is reliant on our ability to produce effective models of reactive nitrogen emission, atmospheric chemistry, transport and deposition (including deposition to the land surface). Over land, N deposition models can be assessed using comparisons to regional monitoring networks of precipitation chemistry (notably those located in North America, Europe and Southeast Asia). No similar datasets exist which would allow observation - model comparisons of wet deposition for the open oceans, because long-term wet deposition records are available for only a handful of remote island sites and rain collection over the open ocean itself is logistically very difficult. In this work we attempt instead to use ~2800 observations of aerosol nitrate and ammonium concentrations, acquired from sampling aboard ships in the period 1995 - 2012, to assess the performance of modelled N deposition fields over the remote ocean. This database is non-uniformly distributed in time and space. We selected three ocean regions (the eastern tropical North Atlantic, the northern Indian Ocean and northwest Pacific) where we considered the density and distribution of observational data is sufficient to provide effective comparison to the model ensemble. Our presentation will focus on the eastern tropical North Atlantic region, which has the best data coverage of the three. We will compare dry deposition fluxes calculated from the observed nitrate

  14. Complex topography influences atmospheric nitrate deposition in a neotropical mountain rainforest

    NASA Astrophysics Data System (ADS)

    Makowski Giannoni, Sandro; Rollenbeck, Rütger; Fabian, Peter; Bendix, Jörg

    2013-11-01

    Future increase of atmospheric nitrogen deposition in tropical regions is expected to have negative impacts on forests ecosystems and related biogeochemical processes. In tropical mountain forests topography causes complex streamflow and rainfall patterns, governing the atmospheric transport of pollutants and the intensity and spatial variability of deposition. The main goal of the current study is to link spatio-temporal patterns of upwind nitrogen emissions and nitrate deposition in the San Francisco Valley (eastern Andes of southern Ecuador) at different altitudinal levels. The work is based on Scanning Imaging Absorption SpectroMeter for Atmospheric CHartographY (SCIAMACHY) retrieved-NO2 concentrations, NOx biomass burning emissions from the Global Fire Emissions Database (GFEDv3), and regional vehicle emissions inventory (SA-INV) for urban emissions in South America. The emission data is used as input for lagrangian atmospheric backward trajectory modeling (FLEXTRA) to model the transport to the study area. The results show that NO concentrations in occult precipitation samples are significantly correlated to long-range atmospheric secondary nitrogen transport at the highest meteorological stations (MSs) only, whereas for NO concentrations in rain samples this correlation is more pronounced at the lower MSs. We conclude that ion concentrations in occult precipitation at the uppermost MSs are mainly linked to distant emission sources via the synoptic circulation impinging the more exposed higher sites. Lower correlations close to the valley bottom are due to a lower occult precipitation frequency and point to a contamination of the samples by local pollution sources not captured by the used emission data sources.

  15. External quality assurance project report for the National Atmospheric Deposition Program’s National Trends Network and Mercury Deposition Network, 2013–14

    USGS Publications Warehouse

    Wetherbee, Gregory A.; Martin, RoseAnn

    2016-01-01

    The Mercury Deposition Network programs include the system blank program and an interlaboratory comparison program. System blank results indicated that maximum total mercury contamination concentrations in samples were less than the third percentile of all Mercury Deposition Network sample concentrations. The Mercury Analytical Laboratory produced chemical concentration results with low bias and variability compared with other domestic and international laboratories that support atmospheric-deposition monitoring.

  16. Diamond synthesis at atmospheric pressure by microwave capillary plasma chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Hemawan, Kadek W.; Gou, Huiyang; Hemley, Russell J.

    2015-11-01

    Polycrystalline diamond has been synthesized on silicon substrates at atmospheric pressure, using a microwave capillary plasma chemical vapor deposition technique. The CH4/Ar plasma was generated inside of quartz capillary tubes using 2.45 GHz microwave excitation without adding H2 into the deposition gas chemistry. Electronically excited species of CN, C2, Ar, N2, CH, Hβ, and Hα were observed in the emission spectra. Raman measurements of deposited material indicate the formation of well-crystallized diamond, as evidenced by the sharp T2g phonon at 1333 cm-1 peak relative to the Raman features of graphitic carbon. Field emission scanning electron microscopy images reveal that, depending on the growth conditions, the carbon microstructures of grown films exhibit "coral" and "cauliflower-like" morphologies or well-facetted diamond crystals with grain sizes ranging from 100 nm to 10 μm.

  17. Deposition velocity of gaseous organic iodine from the atmosphere to rice plants

    SciTech Connect

    Muramatsu, Yasuyuki; Shigeo-Uchida; Sumiya, Misako; Ohmomo, Yoichiro

    1996-11-01

    To obtain parameter values for the assessment of {sup 129}I transfer from the atmosphere to rice, deposition of CH{sub 3}I to rice plants has been studied. The mass normalized deposition velocity (V{sub D}) of CH{sub 3}I for rough (unhulled) rice was 0.00048 cm{sup 3} g{sup {minus}1} s{sup {minus}1}, which is about 1/300 of that of I{sub 2}. Translocation of iodine, deposited as CH{sub 3}I on leaves and stems, to rice grain was negligibly small. Distribution of iodine between hull and inner part of the grain was found to depend also on the chemical forms of atmospheric iodine to be deposited. The ratio of the iodine distribution in a grain exposed to CH{sub 3}I was as follows: rough rice: brown rice (hulled rice):polished rice = 1.0:0.49:0.38. The distribution ratio in polished grains for CH{sub 3}I exposed rice was about 20 times higher than that for I{sub 2}. 22 refs., 1 fig., 6 tabs.

  18. 20th century atmospheric deposition and acidification trends in lakes of the Sierra Nevada, California, USA.

    PubMed

    Heard, Andrea M; Sickman, James O; Rose, Neil L; Bennett, Danuta M; Lucero, Delores M; Melack, John M; Curtis, Jason H

    2014-09-01

    We investigated multiple lines of evidence to determine if observed and paleo-reconstructed changes in acid neutralizing capacity (ANC) in Sierra Nevada lakes were the result of changes in 20th century atmospheric deposition. Spheroidal carbonaceous particles (SCPs) (indicator of anthropogenic atmospheric deposition) and biogenic silica and δ(13)C (productivity proxies) in lake sediments, nitrogen and sulfur emission inventories, climate variables, and long-term hydrochemistry records were compared to reconstructed ANC trends in Moat Lake. The initial decline in ANC at Moat Lake occurred between 1920 and 1930, when hydrogen ion deposition was approximately 74 eq ha(-1) yr(-1), and ANC recovered between 1970 and 2005. Reconstructed ANC in Moat Lake was negatively correlated with SCPs and sulfur dioxide emissions (p = 0.031 and p = 0.009). Reconstructed ANC patterns were not correlated with climate, productivity, or nitrogen oxide emissions. Late 20th century recovery of ANC at Moat Lake is supported by increasing ANC and decreasing sulfate in Emerald Lake between 1983 and 2011 (p < 0.0001). We conclude that ANC depletion at Moat and Emerald lakes was principally caused by acid deposition, and recovery in ANC after 1970 can be attributed to the United States Clean Air Act. PMID:25078969

  19. Atmospheric dry deposition flux of metallic species to the North Sea

    NASA Astrophysics Data System (ADS)

    Ottley, C. J.; Harrison, Roy M.

    Air sampling on a series of 10 research cruises on the North Sea (south of 56°N) has yielded detailed spatial distributions of atmospheric metal concentrations, Al, Ca, Cd, Cu, Fe, Mg, Na, Pb and Zn which closely parallel the results of earlier published models. Air mass back trajectory analysis demonstrates the strong influence which source region may have upon the elemental composition of the North Sea atmosphere. A cascade impactor designed to collect efficiently large as well as small aerosol has produced detailed size distributions from which mass weighted deposition velocity estimates have been produced (Al, 0.33; Cd, 0.24; Cu, 0.44; Fe, 0.30; Pb, 0.13; Zn, 0.30 cm s -1) enabling estimates for the dry deposition flux to the study area to be made. Extrapolation of these data to the whole of the North Sea yields dry deposition flux estimates (Cd, 33; Cu, 350; Pb, 370; Zn, 2640 tonnes yr -1) which are in some instances substantially lower than those previously reported, but nevertheless represent a significant pathway for metallic species to enter this marine environment. The size distributions show the clear dominance that large aerosol has upon the overall dry deposition flux. Flux estimates are thus highly sensitive to the sampling of this large aerosol component, and to assumptions made regarding the sea surface as a source of giant trace metal-enriched particles which act only as a means of recycling marine metals.

  20. A new dust transport approach to quantify anthropogenic sources of atmospheric PM10 deposition on lakes

    NASA Astrophysics Data System (ADS)

    Weiss, Lee; Thé, Jesse; Gharabaghi, Bahram; Stainsby, Eleanor A.; Winter, Jennifer G.

    2014-10-01

    Windblown dust simulations are one of the most uncertain types of atmospheric transport models. This study presents an integrated PM10 emission, transport and deposition model which has been validated using monitored data. This model characterizes the atmospheric phosphorus load focusing on the major local sources within the Lake Simcoe airshed including paved and unpaved roads, agricultural sources, construction sites and aggregate mining sources. This new approach substantially reduces uncertainty by providing improved estimates of the friction velocities than those developed previously. Modeling improvements were also made by generating and validating an hourly windfield using detailed meteorology, topography and land use data for the study area. The model was used to estimate dust emissions generated in the airshed and to simulate the long-range transport and deposition of PM10 to Lake Simcoe. The deposition results from the model were verified against observed bulk collector phosphorus concentration data for both wet and dry deposition. Bulk collector data from stations situated outside the airshed in a remote, undeveloped area were also compared to determine the background contribution from distant sources.

  1. Enhanced solubility and ecological impact of atmospheric phosphorus deposition upon extended seawater exposure.

    PubMed

    Mackey, Katherine R M; Roberts, Kathryn; Lomas, Michael W; Saito, Mak A; Post, Anton F; Paytan, Adina

    2012-10-01

    Atmospheric P solubility affects the amount of P available for phytoplankton in the surface ocean, yet our understanding of the timing and extent of atmospheric P solubility is based on short-term leaching experiments where conditions may differ substantially from the surface ocean. We conducted longer- term dissolution experiments of atmospheric aerosols in filtered seawater, and found up to 9-fold greater dissolution of P after 72 h compared to instantaneous leaching. Samples rich in anthropogenic materials released dissolved inorganic P (DIP) faster than mineral dust. To gauge the effect of biota on the fate of atmospheric P, we conducted field incubations with aerosol samples collected in the Sargasso Sea and Red Sea. In the Sargasso Sea phytoplankton were not P limited, and biological activity enhanced DIP release from aerosols, and aerosols induced biological mineralization of dissolved organic P in seawater, leading to DIP accumulation. However, in the Red Sea where phytoplankton were colimited by P and N, soluble P was rapidly consumed by phytoplankton following aerosol enrichment. Our results suggest that atmospheric P dissolution could continue over multiple days once reaching the surface ocean, and that previous estimates of atmospheric P deposition may underestimate the contribution from this source. PMID:22574853

  2. Limited impact of atmospheric nitrogen deposition on marine productivity due to biogeochemical feedbacks in a global ocean model

    NASA Astrophysics Data System (ADS)

    Somes, Christopher J.; Landolfi, Angela; Koeve, Wolfgang; Oschlies, Andreas

    2016-05-01

    The impact of increasing anthropogenic atmospheric nitrogen deposition on marine biogeochemistry is uncertain. We performed simulations to quantify its effect on nitrogen cycling and marine productivity in a global 3-D ocean biogeochemistry model. Nitrogen fixation provides an efficient feedback by decreasing immediately to deposition, whereas water column denitrification increases more gradually in the slowly expanding oxygen deficient zones. Counterintuitively, nitrogen deposition near oxygen deficient zones causes a net loss of marine nitrogen due to the stoichiometry of denitrification. In our idealized atmospheric deposition simulations that only account for nitrogen cycle perturbations, these combined stabilizing feedbacks largely compensate deposition and suppress the increase in global marine productivity to <2%, in contrast to a simulation that neglects nitrogen cycle feedbacks that predicts an increase of >15%. Our study emphasizes including the dynamic response of nitrogen fixation and denitrification to atmospheric nitrogen deposition to predict future changes of the marine nitrogen cycle and productivity.

  3. An evaluation of atmospheric Nr pollution and deposition in North China after the Beijing Olympics

    NASA Astrophysics Data System (ADS)

    Luo, X. S.; Liu, P.; Tang, A. H.; Liu, J. Y.; Zong, X. Y.; Zhang, Q.; Kou, C. L.; Zhang, L. J.; Fowler, D.; Fangmeier, A.; Christie, P.; Zhang, F. S.; Liu, X. J.

    2013-08-01

    North China is known for its large population densities and rapid development of industry and agriculture. Air quality around Beijing improved substantially during the 2008 Summer Olympics. We measured atmospheric concentrations of various Nr compounds at three urban sites and three rural sites in North China from 2010 to 2012 and estimated N dry and wet deposition by inferential models and the rain gauge method to determine current air conditions with respect to reactive nitrogen (Nr) compounds and nitrogen (N) deposition in Beijing and the surrounding area. NH3, NO2, and HNO3 and particulate NH4+ and NO3-, and NH4+-N and NO3--N in precipitation averaged 8.2, 11.5, 1.6, 8.2 and 4.6 μg N m-3, and 2.9 and 1.9 mg N L-1, respectively, with large seasonal and spatial variability. Atmospheric Nr (especially oxidized N) concentrations were highest at urban sites. Dry deposition of Nr ranged from 35.2 to 60.0 kg N ha-1 yr-1, with wet deposition of Nr of 16.3 to 43.2 kg N ha-1 yr-1 and total deposition of 54.4-103.2 kg N ha-1 yr-1. The rates of Nr dry and wet deposition were 36.4 and 33.2% higher, respectively, at the urban sites than at the rural sites. These high levels reflect the occurrence of a wide range of Nr pollution in North China and suggest that further strict air pollution control measures are required.

  4. ATMOSPHERIC DRY PARTICLE DEPOSITION OF POPS AND TRACE METALS IN AN URBAN- AND INDUSTRIALLY-IMPACTED MID-ATLANTIC ESTUARY (AEOLOS B MID-ATLANTIC)

    EPA Science Inventory

    Emissions of hazardous air pollutants into the coastal urban-industrial atmosphere increase atmospheric depositional fluxes to proximate water bodies. Dry deposition of large particles containing persistent organic pollutants (POPs) and trace metals were a major contribu...

  5. Sediment resuspension by coastal waters: a potential mechanism for nutrient re-cycling on the ocean's margins

    NASA Astrophysics Data System (ADS)

    Fanning, Kent A.; Carder, Kendall L.; Betzer, Peter R.

    1982-08-01

    Nutrient profiles from the continental shelf of the northeastern Gulf of Mexico indicated considerable near-bottom enrichment in silica and nitrate above coarse sediments east of the Mississippi delta. In contrast, near-bottom water of the carbonate-rich West Florida Shelf showed no such enrichmmets. Storm-related suspension apparently produced the enrichments because, in near-bottom waters south of Mobile Bay, silica, nitrate plus nitrite, and suspended load increased subbtantially as a winter storm front passed. Also, laboratory simulation of resuspension by stirring the supernatant seawater over a clay-rich core produced similar increase in silica and nitrate plus nitrite, with ammonia being the apparent precursor to the nitrate and nitrite. Most of the nutrient increase appeared to come from previously deposited sediments in the early stages of resuspension. Using the ratios of nutrients released to sediments resuspended, calculations indicate that resuspension of as little as 1 mm of shelf sediment could intermittenly augment overlying productivity by as much as 100 to 200%. Thus, resuspension may accelerate nutrient recycling on continental margins.

  6. Atmospheric mercury deposition and its contribution of the regional atmospheric transport to mercury pollution at a national forest nature reserve, southwest China.

    PubMed

    Ma, Ming; Wang, Dingyong; Du, Hongxia; Sun, Tao; Zhao, Zheng; Wei, Shiqing

    2015-12-01

    Atmospheric mercury deposition by wet and dry processes contributes to the transformation of mercury from atmosphere to terrestrial and aquatic systems. Factors influencing the amount of mercury deposited to subtropical forests were identified in this study. Throughfall and open field precipitation samples were collected in 2012 and 2013 using precipitation collectors from forest sites located across Mt. Jinyun in southwest China. Samples were collected approximately every 2 weeks and analyzed for total (THg) and methyl mercury (MeHg). Forest canopy was the primary factor on THg and MeHg deposition. Simultaneously, continuous measurements of atmospheric gaseous elemental mercury (GEM) were carried out from March 2012 to February 2013 at the summit of Mt. Jinyun. Atmospheric GEM concentrations averaged 3.8 ± 1.5 ng m(-3), which was elevated compared with global background values. Sources identification indicated that both regional industrial emissions and long-range transport of Hg from central, northeast, and southwest China were corresponded to the elevated GEM levels. Precipitation deposition fluxes of THg and MeHg in Mt. Jinyun were slightly higher than those reported in Europe and North America, whereas total fluxes of MeHg and THg under forest canopy on Mt. Jiuyun were 3 and 2.9 times of the fluxes of THg in wet deposition in the open. Highly elevated litterfall deposition fluxes suggest that even in remote forest areas of China, deposition of atmospheric Hg(0) via uptake by vegetation leaf may be a major pathway for the deposition of atmospheric Hg. The result illustrates that areas with greater atmospheric pollution can be expected to have greater fluxes of Hg to soils via throughfall and litterfall. PMID:26298336

  7. Atmospheric volcanic loading derived from bipolar ice cores: Accounting for the spatial distribution of volcanic deposition

    NASA Astrophysics Data System (ADS)

    Gao, Chaochao; Oman, Luke; Robock, Alan; Stenchikov, Georgiy L.

    2007-05-01

    Previous studies have used small numbers of ice core records of past volcanism to represent hemispheric or global radiative forcing from volcanic stratospheric aerosols. With the largest-ever assembly of volcanic ice core records and state-of-the-art climate model simulations of volcanic deposition, we now have a unique opportunity to investigate the effects of spatial variations on sulfate deposition and on estimates of atmospheric loading. We have combined 44 ice core records, 25 from the Arctic and 19 from Antarctica, and Goddard Institute for Space Studies ModelE simulations to study the spatial distribution of volcanic sulfate aerosols in the polar ice sheets. We extracted volcanic deposition signals by applying a high-pass loess filter to the time series and examining peaks that exceed twice the 31-year running median absolute deviation. Our results suggest that the distribution of volcanic sulfate aerosol follows the general precipitation pattern in both regions, indicating the important role precipitation has played in affecting the deposition pattern of volcanic aerosols. We found a similar distribution pattern for sulfate aerosols from the 1783-1784 Laki and 1815 Tambora eruptions, as well as for the total β activity after the 1952-1954 low-latitude Northern Hemisphere and 1961-1962 high-latitude Northern Hemisphere atmospheric nuclear weapon tests. This confirms the previous assumption that the transport and deposition of nuclear bomb test debris resemble those of volcanic aerosols. We compare three techniques for estimating stratospheric aerosol loading from ice core data: radioactive deposition from nuclear bomb tests, Pinatubo sulfate deposition in eight Antarctic ice cores, and climate model simulations of volcanic sulfate transport and deposition following the 1783 Laki, 1815 Tambora, 1912 Katmai, and 1991 Pinatubo eruptions. By applying the above calibration factors to the 44 ice core records, we have estimated the stratospheric sulfate aerosol

  8. Residual β activity of particulate (234)Th as a novel proxy for tracking sediment resuspension in the ocean.

    PubMed

    Lin, Wuhui; Chen, Liqi; Zeng, Shi; Li, Tao; Wang, Yinghui; Yu, Kefu

    2016-01-01

    Sediment resuspension occurs in the global ocean, which greatly affects material exchange between the sediment and the overlying seawater. The behaviours of carbon, nutrients, heavy metals, and other pollutants at the sediment-seawater boundary will further link to climate change, eutrophication, and marine pollution. Residual β activity of particulate (234)Th (RAP234) is used as a novel proxy to track sediment resuspension in different marine environments, including the western Arctic Ocean, the South China Sea, and the Southern Ocean. Sediment resuspension identified by high activity of RAP234 is supported by different lines of evidence including seawater turbidity, residence time of total (234)Th, Goldschmidt's classification, and ratio of RAP234 to particulate organic carbon. A conceptual model is proposed to elucidate the mechanism for RAP234 with dominant contributions from (234)Th-(238)U and (212)Bi-(228)Th. The 'slope assumption' for RAP234 indicated increasing intensity of sediment resuspension from spring to autumn under the influence of the East Asian monsoon system. RAP234 can shed new light on (234)Th-based particle dynamics and should benefit the interpretation of historical (234)Th-(238)U database. RAP234 resembles lithophile elements and has broad implications for investigating particle dynamics in the estuary-shelf-slope-ocean continuum and linkage of the atmosphere-ocean-sediment system. PMID:27252085

  9. Residual β activity of particulate 234Th as a novel proxy for tracking sediment resuspension in the ocean

    PubMed Central

    Lin, Wuhui; Chen, Liqi; Zeng, Shi; Li, Tao; Wang, Yinghui; Yu, Kefu

    2016-01-01

    Sediment resuspension occurs in the global ocean, which greatly affects material exchange between the sediment and the overlying seawater. The behaviours of carbon, nutrients, heavy metals, and other pollutants at the sediment-seawater boundary will further link to climate change, eutrophication, and marine pollution. Residual β activity of particulate 234Th (RAP234) is used as a novel proxy to track sediment resuspension in different marine environments, including the western Arctic Ocean, the South China Sea, and the Southern Ocean. Sediment resuspension identified by high activity of RAP234 is supported by different lines of evidence including seawater turbidity, residence time of total 234Th, Goldschmidt’s classification, and ratio of RAP234 to particulate organic carbon. A conceptual model is proposed to elucidate the mechanism for RAP234 with dominant contributions from 234Th-238U and 212Bi-228Th. The ‘slope assumption’ for RAP234 indicated increasing intensity of sediment resuspension from spring to autumn under the influence of the East Asian monsoon system. RAP234 can shed new light on 234Th-based particle dynamics and should benefit the interpretation of historical 234Th-238U database. RAP234 resembles lithophile elements and has broad implications for investigating particle dynamics in the estuary-shelf-slope-ocean continuum and linkage of the atmosphere-ocean-sediment system. PMID:27252085

  10. Residual β activity of particulate 234Th as a novel proxy for tracking sediment resuspension in the ocean

    NASA Astrophysics Data System (ADS)

    Lin, Wuhui; Chen, Liqi; Zeng, Shi; Li, Tao; Wang, Yinghui; Yu, Kefu

    2016-06-01

    Sediment resuspension occurs in the global ocean, which greatly affects material exchange between the sediment and the overlying seawater. The behaviours of carbon, nutrients, heavy metals, and other pollutants at the sediment-seawater boundary will further link to climate change, eutrophication, and marine pollution. Residual β activity of particulate 234Th (RAP234) is used as a novel proxy to track sediment resuspension in different marine environments, including the western Arctic Ocean, the South China Sea, and the Southern Ocean. Sediment resuspension identified by high activity of RAP234 is supported by different lines of evidence including seawater turbidity, residence time of total 234Th, Goldschmidt’s classification, and ratio of RAP234 to particulate organic carbon. A conceptual model is proposed to elucidate the mechanism for RAP234 with dominant contributions from 234Th-238U and 212Bi-228Th. The ‘slope assumption’ for RAP234 indicated increasing intensity of sediment resuspension from spring to autumn under the influence of the East Asian monsoon system. RAP234 can shed new light on 234Th-based particle dynamics and should benefit the interpretation of historical 234Th-238U database. RAP234 resembles lithophile elements and has broad implications for investigating particle dynamics in the estuary-shelf-slope-ocean continuum and linkage of the atmosphere-ocean-sediment system.

  11. Mobile load simulators - A tool to distinguish between the emissions due to abrasion and resuspension of PM10 from road surfaces

    NASA Astrophysics Data System (ADS)

    Gehrig, R.; Zeyer, K.; Bukowiecki, N.; Lienemann, P.; Poulikakos, L. D.; Furger, M.; Buchmann, B.

    2010-12-01

    Mechanically produced abrasion particles and resuspension processes are responsible for a significant part of the PM10 emissions of road traffic. However, specific differentiation between PM10 emissions due to abrasion and resuspension from road pavement is very difficult due to their similar elemental composition and highly correlated variation in time. In this work Mobile Load Simulators were used to estimate PM10 emission factors for pavement abrasion and resuspension on different pavement types for light and heavy duty vehicles. From the experiments it was derived that particle emissions due to abrasion from pavements in good condition are quite low in the range of only a few mg·km -1 per vehicle if quantifiable at all. Considerable abrasion emissions, however, can occur from damaged pavements. Resuspension of deposited dust can cause high and extremely variable particle emissions depending strongly on the dirt load of the road surface. Porous pavements seem to retain deposited dust better than dense pavements, thus leading to lower emissions due to resuspension compared to pavements with a dense structure (e.g. asphalt concrete). Tyre wear seemed not to be a quantitatively significant source of PM10 emissions from road traffic.

  12. Engineering of pulsed laser deposited calcium phosphate biomaterials in controlled atmospheres

    NASA Astrophysics Data System (ADS)

    Drukteinis, Saulius E.

    Synthetic calcium phosphates (CAP) such as hydroxyapatite (HA) have been used as regenerative bone graft materials and also as thin films to improve the integration of biomedical implant devices within skeletal tissue. Pulsed laser deposition (PLD) can deposit crystalline HA with significant adhesion on titanium biomaterials. However, there are PLD processing constraints due to the complex physical and chemical interactions occurring simultaneously during PLD, which influence ablation plume formation and development. In this investigation PLD CAP films were engineered with a focus on novel decoupling of partial pressure of H2O (g) ( PH2O ) from total background pressure, in combination with substrate heat treatment and laser energy density control. Characterization of these films was performed with X-ray Diffraction, Scanning Electron Microscopy, Energy Dispersive X-ray Spectroscopy, Fourier Transform Infrared Spectroscopy, and Optical Profilometry. In vitro cellular adhesion testing was also performed using osteoblast (MC3T3) cell lines to evaluate adhesion of bone-forming cells on processed PLD CAP samples. Preferred a-axis orientation films were deposited in H2O (g) saturated atmospheres with reduced laser fluence (< 4 J/cm2). Crystalline HA/tetracalcium phosphate (TTCP) films were deposited in H2O ( g)-deficient atmospheres with higher laser fluence (> 3 J/cm 2). Varied PH2O resulted in control of biphasic HA/TTCP composition with increasing TTCP at lower PH2O . These were dense continuous films composed of micron-scale particles. Cellular adhesion assays did not demonstrate a significant difference between osteoblast adhesion density on HA films compared with biphasic HA/TTCP films. Room temperature PLD at varied PH2O combined with furnace heat treatment resulted in controlled variation in surface amplitude parameters including surface roughness (S a), root mean square (Sq), peak to valley height (St), and ten-point height ( Sz). These discontinuous films were

  13. 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. PMID:25525712

  14. National Atmospheric Deposition Program (NADP) Networks: Data on the chemistry of precipitation

    DOE Data Explorer

    The National Atmospheric Deposition Program/National Trends Network (NADP/NTN) is a nationwide network of sites collecting data on the chemistry of precipitation for monitoring of geographical and temporal long-term trends. The precipitation at each station is collected weekly according to strict clean-handling procedures. It is then sent to the Central Analytical Laboratory where it is analyzed for hydrogen (acidity as pH), sulfate, nitrate, ammonium, chloride, and base cations (such as calcium, magnesium, potassium and sodium). The network is a cooperative effort between many different groups, including the State Agricultural Experiment Stations, U.S. Geological Survey, U.S. Department of Agriculture, and numerous other governmental and private entities. DOE is one of these cooperating agencies, though it plays a smaller funding role than some of the other federal sources. Since 1978, the NADP/NTN has grown from 22 stations to over 250 sites spanning the continental United States, Alaska, and Puerto Rico, and the Virgin Islands. The National Atmospheric Deposition Program has also expanded its sampling to two additional networks: 1) the Mercury Deposition Network (MDN), currently with over 90 sites, was formed in 1995 to collect weekly samples of precipitation which are analyzed by Frontier Geosciences for total mercury, and 2) the Atmospheric Integrated Research Monitoring Network (AIRMoN), formed for the purpose of studying precipitation chemistry trends with greater temporal resolution than the NTN. [taken from the NADP History and Overview page at http://nadp.sws.uiuc.edu/nadpoverview.asp] Data from these networks are freely available in via customized search interfaces linked to interactive maps of the stations in the three networks. Animated Isopleth maps in Flash and PowerPoint are also available to display concentrations and depositions various substances such as sulfate, nitrate, etc. (Specialized Interface)

  15. 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.

  16. The impact of canopy exchange on differences observed between atmospheric deposition and throughfall fluxes

    NASA Astrophysics Data System (ADS)

    Draaijers, G. P. J.; Erisman, J. W.; Leeuwen, N. F. M. Van; Römer, F. G.; Winkel, B. H. Te; Veltkamp, A. C.; Vermeulen, A. T.; Wyers, G. P.

    To study the impact of canopy exchange on differences observed between atmospheric deposition and throughfall fluxes, several field experiments were performed at the Speulder forest in The Netherlands. Relevant information was obtained by (i) measuring open-field precipitation and throughfall fluxes with different time resolutions, using two canopy exchange models, (ii) by comparing results from surface wash experiments using real and artificial twigs, respectively, and (iii) by comparing throughfall flux estimates with atmospheric deposition estimates from micrometeorological measurements and inferential modelling. Canopy uptake of gases through stomata was estimated using measured air concentrations and a stomatal conductance model. Specific information on canopy leaching of soil-derived sulphate was provided by a 35S tracer experiment. Sulphur was found to behave conservatively within the canopy, with SO 2 uptake more or less balancing leaching of soil-derived SO 2-4. Significant stomatal uptake of NO 2, HNO 2 and NH 3 was calculated as well as uptake of H + and NH 4+ from water layers covering the tree surface. Experiments did not indicate significant uptake of N0 3- in solution. Canopy uptake of H + and NH4+ was countered by leaching of K +, Ca 2+ and Mg 2+. Part of the leaching of K +, Ca 2+ and Mg 2+ (15%) took place along with weak organic acids. No significant canopy exchange was found for Na + and Cl -. Differences observed between atmospheric deposition and throughfall fluxes could almost completely be explained by canopy exchange, the difference between NO y deposition and N0 3 throughfall flux being the only exception.

  17. Critical loads of nitrogen deposition and critical levels of atmospheric ammonia for mediterranean evergreen woodlands

    NASA Astrophysics Data System (ADS)

    Pinho, P.; Theobald, M. R.; Dias, T.; Tang, Y. S.; Cruz, C.; Martins-Loução, M. A.; Máguas, C.; Sutton, M.; Branquinho, C.

    2011-11-01

    Nitrogen (N) has emerged in recent years as a key factor associated with global changes, with impacts on biodiversity, ecosystems functioning and human health. In order to ameliorate the effects of excessive N, safety thresholds have been established, such as critical loads (deposition fluxes) and levels (concentrations). For Mediterranean ecosystems, few studies have been carried out to assess these parameters. Our objective was therefore to determine the critical loads of N deposition and long-term critical levels of atmospheric ammonia for Mediterranean evergreen woodlands. For that we have considered changes in epiphytic lichen communities, which have been shown to be one of the most sensitive to excessive N. Based on a classification of lichen species according to their tolerance to N we grouped species into response functional groups, which we used as a tool to determine the critical loads and levels. This was done under Mediterranean climate, in evergreen cork-oak woodlands, by sampling lichen functional diversity and annual atmospheric ammonia concentrations and modelling N deposition downwind from a reduced N source (a cattle barn). By modelling the highly significant relationship between lichen functional groups and N deposition, the critical load was estimated to be below 26 kg (N) ha-1 yr-1, which is within the upper range established for other semi-natural ecosystems. By modelling the highly significant relationship of lichen functional groups with annual atmospheric ammonia concentration, the critical level was estimated to be below 1.9 μg m-3, in agreement with recent studies for other ecosystems. Taking into account the high sensitivity of lichen communities to excessive N, these values should be taken into account in policies that aim at protecting Mediterranean woodlands from the initial effects of excessive N.

  18. Influence of variable rates of neritic carbonate deposition on atmospheric carbon dioxide and pelagic sediments

    NASA Technical Reports Server (NTRS)

    Walker, J. C.; Opdyke, B. C.

    1995-01-01

    Short-term imbalances in the global cycle of shallow water calcium carbonate deposition and dissolution may be responsible for much of the observed Pleistocene change in atmospheric carbon dioxide content. However, any proposed changes in the alkalinity balance of the ocean must be reconciled with the sedimentary record of deep-sea carbonates. The possible magnitude of the effect of shallow water carbonate deposition on the dissolution of pelagic carbonate can be tested using numerical simulations of the global carbon cycle. Boundary conditions can be defined by using extant shallow water carbonate accumulation data and pelagic carbonate deposition/dissolution data. On timescales of thousands of years carbonate deposition versus dissolution is rarely out of equilibrium by more than 1.5 x 10(13) mole yr-1. Results indicate that the carbonate chemistry of the ocean is rarely at equilibrium on timescales less than 10 ka. This disequilibrium is probably due to sea level-induced changes in shallow water calcium carbonate deposition/dissolution, an interpretation that does not conflict with pelagic sedimentary data from the central Pacific.

  19. Influence of variable rates of neritic carbonate deposition on atmospheric carbon dioxide and pelagic sediments.

    PubMed

    Walker, J C; Opdyke, B C

    1995-06-01

    Short-term imbalances in the global cycle of shallow water calcium carbonate deposition and dissolution may be responsible for much of the observed Pleistocene change in atmospheric carbon dioxide content. However, any proposed changes in the alkalinity balance of the ocean must be reconciled with the sedimentary record of deep-sea carbonates. The possible magnitude of the effect of shallow water carbonate deposition on the dissolution of pelagic carbonate can be tested using numerical simulations of the global carbon cycle. Boundary conditions can be defined by using extant shallow water carbonate accumulation data and pelagic carbonate deposition/dissolution data. On timescales of thousands of years carbonate deposition versus dissolution is rarely out of equilibrium by more than 1.5 x 10(13) mole yr-1. Results indicate that the carbonate chemistry of the ocean is rarely at equilibrium on timescales less than 10 ka. This disequilibrium is probably due to sea level-induced changes in shallow water calcium carbonate deposition/dissolution, an interpretation that does not conflict with pelagic sedimentary data from the central Pacific. PMID:11540240

  20. Chain Assemblies from Nanoparticles Synthesized by Atmospheric Pressure Plasma Enhanced Chemical Vapor Deposition: The Computational View.

    PubMed

    Mishin, Maxim V; Zamotin, Kirill Y; Protopopova, Vera S; Alexandrov, Sergey E

    2015-12-01

    This article refers to the computational study of nanoparticle self-organization on the solid-state substrate surface with consideration of the experimental results, when nanoparticles were synthesised during atmospheric pressure plasma enhanced chemical vapor deposition (AP-PECVD). The experimental study of silicon dioxide nanoparticle synthesis by AP-PECVD demonstrated that all deposit volume consists of tangled chains of nanoparticles. In certain cases, micron-sized fractals are formed from tangled chains due to deposit rearrangement. This work is focused on the study of tangled chain formation only. In order to reveal their formation mechanism, a physico-mathematical model was developed. The suggested model was based on the motion equation solution for charged and neutral nanoparticles in the potential fields with the use of the empirical interaction potentials. In addition, the computational simulation was carried out based on the suggested model. As a result, the influence of such experimental parameters as deposition duration, particle charge, gas flow velocity, and angle of gas flow was found. It was demonstrated that electrical charges carried by nanoparticles from the discharge area are not responsible for the formation of tangled chains from nanoparticles, whereas nanoparticle kinetic energy plays a crucial role in deposit morphology and density. The computational results were consistent with experimental results. PMID:26682441

  1. Surface reactions as carbon removal mechanism in deposition of silicon dioxide films at atmospheric pressure

    SciTech Connect

    Reuter, R.; Ellerweg, D.; Keudell, A. von; Benedikt, J.

    2011-03-14

    The deposition of thin SiO{sub x}C{sub y}H{sub z} or SiO{sub x}H{sub y} films by means of an atmospheric pressure microplasma jet with helium/hexamethyldisiloxane (HMDSO)/O{sub 2} mixtures and the surface reactions involving oxygen have been studied. It is shown, that the carbon content in the film can be controlled by choosing the right O{sub 2}/HMDSO ratio in the gas mixture. The microplasma jet geometry and localization of the deposition at a spot of few square millimeters allows studying the role of oxygen in the deposition process. This is done by alternating application of He/HMDSO plasma and He/O{sub 2} plasma to the same deposition area, here achieved by a treatment of a rotating substrate by two jets with above mentioned gas mixtures. It is shown that carbon-free SiO{sub x}H{sub y} film can be deposited in this way and that surface reaction with oxygen is the main loss mechanism of carbon from the film.

  2. Increased atmospheric deposition of mercury in reference lakes near major urban areas

    USGS Publications Warehouse

    Van Metre, P.C.

    2012-01-01

    Atmospheric deposition of Hg is the predominant pathway for Hg to reach sensitive ecosystems, but the importance of emissions on near-field deposition remains unclear. To better understand spatial variability in Hg deposition, mercury concentrations were analyzed in sediment cores from 12 lakes with undeveloped watersheds near to (<50 km) and remote from (>150 km) several major urban areas in the United States. Background and focusing corrected Hg fluxes and flux ratios (modern to background) in the near-urban lakes (68 ?? 6.9 ??g m -2 yr -1 and 9.8 ?? 4.8, respectively) greatly exceed those in the remote lakes (14 ?? 9.3 ??g m -2 yr -1 and 3.5 ?? 1.0) and the fluxes are strongly related to distance from the nearest major urban area (r 2 = 0.87) and to population and Hg emissions within 50-100 km of the lakes. Comparison to monitored wet deposition suggests that dry deposition is a major contributor of Hg to lakes near major urban areas. ?? 2011 Elsevier Ltd. All rights reserved.

  3. Four studies on effects of environmental factors on the quality of National Atmospheric Deposition Program measurements

    USGS Publications Warehouse

    Wetherbee, Gregory A.; Latysh, Natalie E.; Lehmann, Christopher M.B.; Rhodes, Mark F.

    2011-01-01

    Selected aspects of National Atmospheric Deposition Program / National Trends Network (NADP/NTN) protocols are evaluated in four studies. Meteorological conditions have minor impacts on the error in NADP/NTN sampling. Efficiency of frozen precipitation sample collection is lower than for liquid precipitation samples. Variability of NTN measurements is higher for relatively low-intensity deposition of frozen precipitation than for higher-intensity deposition of liquid precipitation. Urbanization of the landscape surrounding NADP/NTN sites is not affecting trends in wet-deposition chemistry data to a measureable degree. Five NADP siting criteria intended to preserve wet-deposition sample integrity have varying degrees of effectiveness. NADP siting criteria for objects within the 90 degrees cones and trees within the 120 degrees cones projected from the collector bucket to sky are important for protecting sample integrity. Tall vegetation, fences, and other objects located within 5 meters of the collectors are related to the frequency of visible sample contamination, indicating the importance of these factors in NADP siting criteria.

  4. Assessing the atmospheric deposition of mercury to Lake Michigan: The importance of the Chicago/Gary urban area on wet and dry deposition

    NASA Astrophysics Data System (ADS)

    Landis, Matthew Scott

    1998-12-01

    Mercury is a toxic bioaccumulative substance found in aquatic ecosystems. The results of the first study of atmospheric mercury deposition into Lake Michigan and the relative importance of the Chicago/Gary urban area were investigated as part of the Lake Michigan Mass Balance Study (LMMBS) and the Atmospheric Exchange Over Lakes and Oceans Study (AEOLOS). Event wet-only precipitation, total aerosol, and vapor phase samples were collected for mercury and trace element determinations from five sites around Lake Michigan from July 1994 through October 1995 as part of the LMMBS. In addition, intensive over-water measurements were conducted aboard the EPA research vessel Lake Guardian during the summer of 1994 and the winter of 1995 as part of the AEOLOS. Atmospheric mercury concentrations were from two to ten times higher in the Chicago/Gary urban area. Wet and dry Hg deposition (including reactive gaseous Hg) were calculated to Lake Michigan using a hybrid receptor modeling framework. The model utilized mercury monitoring data collected during the LMMBS and AEOLOS together with high resolution over-water meteorological data provided by the National Oceanic and Atmospheric Administration. Atmospheric deposition was found to be the primary pathway for mercury input to Lake Michigan, contributing approximately 84% of the estimated 1419 Kg annual flux. Wet deposition (10.6 μg m-2) and dry deposition (10.0 μg m-2) contributed almost equally to the annual atmospheric Hg deposition of 20.6 μg m-2 (1189 Kg). A strong urban influence was observed in the over-water mercury deposition estimates in the southern portion of the lake. An independent meteorological transport analysis determined that local sources in the Chicago/Gary urban area significantly impacted the LMMBS sites around Lake Michigan. The Chicago/Gary urban area was found to contribute about 20% (127 Kg) of the annual atmospheric mercury deposition to Lake Michigan. Multivariate statistical analysis of

  5. The effects of atmospheric nitrogen deposition in the Rocky Mountains of Colorado and southern Wyoming, USA-a critical review.

    PubMed

    Burns, Douglas A

    2004-01-01

    The Rocky Mountains of Colorado and southern Wyoming receive atmospheric nitrogen (N) deposition that ranges from 2 to 7 kg ha(-1) yr(-1), and some previous research indicates pronounced ecosystem effects at the highest rates of deposition. This paper provides a critical review of previously published studies on the effects of atmospheric N deposition in the region. Plant community changes have been demonstrated through N fertilization studies, however, N limitation is still widely reported in alpine tundra and subalpine forests of the Front Range, and sensitivity to changes in snow cover alone indicate the importance of climate sensitivity in these ecosystems. Retention of N in atmospheric wet deposition is <50% in some watersheds east of the Continental Divide, which reflects low biomass and a short growing season relative to the timing and N load in deposition. Regional upward temporal trends in surface water NO(3)(-) concentrations have not been demonstrated, and future trend analyses must consider the role of climate as well as N deposition. Relatively high rates of atmospheric N deposition east of the Divide may have altered nutrient limitation of phytoplankton, species composition of diatoms, and amphibian populations, but most of these effects have been inconclusive to date, and additional studies are needed to confirm hypothesized cause and effect relations. Projected future population growth and energy use in Colorado and the west increase the likelihood that the subtle effects of atmospheric N deposition now evident in the Front Range will become more pronounced and widespread in the future. PMID:14568725

  6. Chemical cycling and deposition of atmospheric mercury: Global constraints from observations

    NASA Astrophysics Data System (ADS)

    Selin, Noelle E.; Jacob, Daniel J.; Park, Rokjin J.; Yantosca, Robert M.; Strode, Sarah; Jaeglé, Lyatt; Jaffe, Daniel

    2007-01-01

    We use a global 3-D model of atmospheric mercury (GEOS-Chem) to interpret worldwide observations of total gaseous mercury (TGM) and reactive gaseous mercury (RGM) in terms of the constraints they provide on the chemical cycling and deposition of mercury. Our simulation including a global mercury source of 7000 Mg yr-1 and a TGM lifetime of 0.8 years reproduces the magnitude and large-scale variability of TGM observations at land sites. However, it cannot capture observations of high TGM from ship cruises, implying a problem either in the measurements or in our fundamental understanding of mercury sources. Observed TGM seasonal variation at northern midlatitudes is consistent with a photochemical oxidation for Hg(0) partly balanced by photochemical reduction of Hg(II). Observations of increasing RGM with altitude imply a long lifetime of Hg(II) in the free troposphere. We find in the model that Hg(II) dominates over Hg(0) in the upper troposphere and stratosphere and that subsidence is the principal source of Hg(II) at remote surface sites. RGM observations at Okinawa Island (Japan) show large diurnal variability implying fast deposition, which we propose is due to RGM uptake by sea-salt aerosols. Observed mercury wet deposition fluxes in the United States show a maximum in the southeast, which we attribute to photochemical oxidation of the global Hg(0) pool. They also show a secondary maximum in the industrial Midwest due to regional emissions that is underestimated in the model, possibly because of excessive dry deposition relative to wet (dry deposition accounts for 68% of total mercury deposition in the United States in the model, but this is sensitive to the assumed phase of Hg(II)). We estimate that North American anthropogenic emissions contribute on average 20% to U.S. mercury deposition.

  7. Do N-isotopes in atmospheric nitrate deposition reflect air pollution levels?

    NASA Astrophysics Data System (ADS)

    Beyn, Fabian; Matthias, Volker; Aulinger, Armin; Dähnke, Kirstin

    2015-04-01

    Dry and wet deposition of atmospheric reactive nitrogen compounds mostly originate from anthropogenic NH3 and NOX sources. Regarding land-borne pollutants, coastal environments usually have a lower pollution level than terrestrial/urban areas, which have a greater anthropogenic imprint. To investigate this spatial characteristic, we measured NO3- and NH4+ deposition and N isotopes of NO3-(δ15N-NO3-) in 94 and 88 wet and dry deposition samples, respectively, at a coastal (List on Sylt) and a terrestrial/urban site (Geesthacht) in Germany from May 2012 to May 2013. A higher total N deposition rate was observed in Geesthacht (10.4 vs. 8.9 kg N ha-1 yr-1) due to higher NH4+ deposition, which can be explained by more agricultural influence. Surprisingly, overall NO3- fluxes were higher at the coastal site than at the terrestrial/urban site. We assume that sea-salt aerosols and the increased influence of NOX emissions from ships in most recent times compensate the higher terrestrial/urban pollution level and thus lead to higher NO3- fluxes in dry and comparable fluxes in wet deposition at the coastal site, despite a much lower impact of land-based sources. In line with this, overall mean N isotopes values of NO3- show higher values in List than in Geesthacht in dry (+3.1 vs. +1.9‰) as well as in wet deposition (-0.1 vs. -1.0‰). This surprising result can mainly be attributed to an emerging source of NOX, ship emissions, which have a distinctly higher impact at the coastal site. The usage of heavy oil and possibly new technologies in marine engines, which emit more enriched 15N in comparison to older engines, caused the spatial isotopic differences.

  8. Pitfalls and new mechanisms in moss isotope biomonitoring of atmospheric nitrogen deposition.

    PubMed

    Liu, Xue-Yan; Koba, Keisuke; Liu, Cong-Qiang; Li, Xiao-Dong; Yoh, Muneoki

    2012-11-20

    Moss N isotope (δ(15)N(bulk)) has been used to monitor N deposition, but it remains questionable whether inhibition of nitrate reductase activity (NRA) by reduced dissolved N (RDN) engenders overestimation of RDN in deposition when using moss δ(15)N(bulk). We tested this question by investigation of δ(15)N(bulk) and δ(15)NO(3)(-) in mosses under the dominance of RDN in N depositions of Guiyang, SW China. The δ(15)N(bulk) of mosses on bare rock (-7.9‰) was unable to integrate total dissolved N (TDN) (δ(15)N = -6.3‰), but it reflected δ(15)N-RDN (-7.5‰) exactly. Moreover, δ(15)N-NO(3)(-) in mosses (-1.7‰) resembled that of wet deposition (-1.9‰). These isotopic approximations, together with low isotopic enrichment with moss [NO(3)(-)] variations, suggest the inhibition of moss NRA by RDN. Moreover, isotopic mixing modeling indicated a negligible contribution from NO(3)(-) to moss δ(15)N(bulk) when the RDN/NO(3)(-) reaches 3.8, at which maximum overestimation (21%) of RDN in N deposition can be generated using moss δ(15)N(bulk) as δ(15)N-TDN. Moss δ(15)N-NO(3)(-) can indicate atmospheric NO(3)(-) under distinctly high RDN/NO(3)(-) in deposition, although moss δ(15)N(bulk) can reflect only the RDN therein. These results reveal pitfalls and new mechanisms associated with moss isotope monitoring of N deposition and underscore the importance of biotic N dynamics in biomonitoring studies. PMID:23050838

  9. Atmospheric Nitrogen Deposition Threatens Biodiversity: Development of Novel Mitigation Policies in California

    NASA Astrophysics Data System (ADS)

    Weiss, S. B.

    2011-12-01

    Atmospheric nitrogen deposition threatens biodiversity in many parts of the world. In California, 20% of the land surface receives > 5 kg-N ha-1 year-1, with hotspots receiving > 50 kg-N ha-1 year-1. Documented impacts of N-deposition include increased growth of annual grass and other invasives in coastal sage scrub, serpentine grasslands, vernal pools, and deserts, altered nutrient cycling and fuel accumulation of montane forests, enhanced fire cycles, nitrate leaching into surface and groundwater, and eutrophication of montane lakes such as Lake Tahoe. 40% of listed threatened and endangered plants are exposed to > 5 kg-N ha-1 year-1, and N-deposition is arguably a greater immediate threat to biodiversity than is climate change. Appropriate policy responses are lagging, because the magnitude of N-deposition impacts on biodiversity is poorly known in the broader conservation/regulatory community and the general public. Policies to decrease emissions and deposition are clearly the ultimate solution on a decadal time scale. In the interim, habitat management is critical to preventing extinction of many species. This presentation reviews recent policies and regulatory actions in California that address N-deposition impacts on biodiversity. The immediate and long-term needs for invasive weed management are overwhelming and require long-term endowment funding. Mitigation requirements under the US Endangered Species Act have been used to secure land and management resources. The on-going story of the threatened Bay checkerspot butterfly, from the first precedent setting mitigation in 2001 through a regional Habitat Conservation Plan (HCP), illustrates the development of these novel policies based on science, regulatory authority, grassroots activism, public education, habitat restoration, and legal actions. The 50-year HCP will ultimately result in a network of conserved lands with management endowments. Eventually N-deposition may be reduced below critical loads

  10. Low temperature atmospheric pressure chemical vapor deposition of group 14 oxide films

    SciTech Connect

    Hoffman, D.M.; Atagi, L.M. |; Chu, Wei-Kan; Liu, Jia-Rui; Zheng, Zongshuang; Rubiano, R.R.; Springer, R.W.; Smith, D.C.

    1994-06-01

    Depositions of high quality SiO{sub 2} and SnO{sub 2} films from the reaction of homoleptic amido precursors M(NMe{sub 2})4 (M = Si,Sn) and oxygen were carried out in an atmospheric pressure chemical vapor deposition r. The films were deposited on silicon, glass and quartz substrates at temperatures of 250 to 450C. The silicon dioxide films are stoichiometric (O/Si = 2.0) with less than 0.2 atom % C and 0.3 atom % N and have hydrogen contents of 9 {plus_minus} 5 atom %. They are deposited with growth rates from 380 to 900 {angstrom}/min. The refractive indexes of the SiO{sub 2} films are 1.46, and infrared spectra show a possible Si-OH peak at 950 cm{sup {minus}1}. X-Ray diffraction studies reveal that the SiO{sub 2} film deposited at 350C is amorphous. The tin oxide films are stoichiometric (O/Sn = 2.0) and contain less than 0.8 atom % carbon, and 0.3 atom % N. No hydrogen was detected by elastic recoil spectroscopy. The band gap for the SnO{sub 2} films, as estimated from transmission spectra, is 3.9 eV. The resistivities of the tin oxide films are in the range 10{sup {minus}2} to 10{sup {minus}3} {Omega}cm and do not vary significantly with deposition temperature. The tin oxide film deposited at 350C is cassitterite with some (101) orientation.

  11. Atmospheric deposition of pesticides to an agricultural watershed of the Chesapeake Bay.

    PubMed

    Kuang, Zhihua; McConnell, Laura L; Torrents, Alba; Meritt, Donald; Tobash, Stephanie

    2003-01-01

    The Choptank River watershed, located on the Delmarva Peninsula of the Chesapeake Bay, is dominated by agricultural land use, which makes it vulnerable to runoff and atmospheric deposition of pesticides. Agricultural and wildlife areas are in close proximity and off-site losses of pesticides may contribute to toxic effects on sensitive species of plants and animals. High-volume air samples (n = 31) and event-based rain samples (n = 71) were collected from a single location in the watershed representing regional background conditions. Surface water samples were collected from eight stations in the tidal portion of the river on five occasions during 2000. Chlorothalonil, metolachlor, atrazine, simazine, endosulfan, and chlorpyrifos were frequently detected in the air and rain, with maximal concentrations during the period when local or regional crops were planted. The wet deposition load to the watershed was estimated at 150 +/- 16, 61 +/- 7, and 51 +/- 6 kg yr(-1) for chlorothalonil, metolachlor, and atrazine, respectively. The high wet deposition load compared with the estimated annual usage for chlorothalonil (13%) and endosulfan (14-90%) suggests an atmospheric source from outside the watershed. Net air-water gas exchange fluxes for metolachlor varied from -44 +/- 19 to 9.3 +/- 4.1 ng m(-2) d(-1) with negative values indicating net deposition. Wet deposition accounted for 3 to 20% of the total metolachlor mass in the Choptank River and was a more important source to the river than gas exchange. Estimates of herbicide flux presented here are probably a low estimate and actual rates may be significantly higher in areas closer to pesticide application. PMID:14535301

  12. Atmospheric dispersion and deposition of iodine-131 released from the Hanford Site

    SciTech Connect

    Ramsdell, J.V.; Simonen, C.A.; Burk, K.W.; Stage, S.A.

    1994-06-01

    Approximately 2.6x10{sup 4} TBq (700,000 curies) of iodine-131 were released to the air from reactor fuel processing plants on the Hanford Site in southcentral Washington State from December 1944 through December 1949. The Hanford Environmental Dose Reconstruction (HEDR) Project developed a suite of codes to estimate the doses that might have resulted from these releases. The Regional Atmospheric Transport Code for Hanford Emission Tracking (RATCHET) computer code is part of this suite. The RATCHET code implements a Lagrangian-trajectory, Gaussian-puff dispersion model that uses hourly meteorological and release rate data to estimate daily time-integrated air concentrations and surface contamination for use in dose estimates. In this model, iodine is treated as a mixture of three species (nominally, inorganic gases, organic gases, and particles). Model deposition parameters are functions of the mixture and meteorological conditions. A resistance model is used to calculate dry deposition velocities. Equilibrium between concentrations in the precipitation and the air near the ground is assumed in calculating wet deposition of gases, and irreversible washout of the particles is assumed. RATCHET explicitly treats the uncertainties in model parameters and meteorological conditions. Uncertainties in iodine-131 release rates and partitioning among the nominal species are treated by varying model input. The results of 100 model runs for December 1944 through December 1949 indicate that monthly average air concentrations and deposition have uncertainties ranging from a factor of two near the center of the time-integrated plume to more than an order of magnitude near the edge. These results indicate that -10% of the iodine-131 released to the atmosphere decayed during transit in the study area, -56% was deposited within the study area, and the remaining 34% was transported out of the study area while still in the air.

  13. Dry atmospheric deposition rates of metals along a coastal transect in southern California

    NASA Astrophysics Data System (ADS)

    Sabin, Lisa D.; Schiff, Kenneth C.

    While recent studies indicate atmospheric deposition is a significant source of metals to the Santa Monica Bay and coastal river systems of the Los Angeles area, the spatial extent of the atmospheric source along the entire southern California coast has not been measured in 30 years. This study provides measurements of dry atmospheric deposition of chromium, copper, lead, nickel and zinc at eight sites located along the coast between Santa Barbara and San Diego, and compares these data to historic measurements from the 1970s. Median dry deposition fluxes across sites ranged between 0.23 and 3.6 (chromium), 0.21 and 5.4 (nickel), 0.52 and 14 (lead), 0.89 and 29 (copper), and 4.8 and 160 (zinc) μg m -2 day -1. Differences in metal dry deposition rates observed between sites were dominated by proximity to urban areas and/or other nearby sources, with the highest metal fluxes observed near the Los Angeles Harbor (LAH) and San Diego Bay (SDB) sites. Compared with data from the 1970s, lead fluxes were typically one to two orders of magnitude lower in the present study (2006), indicating atmospheric sources of this metal have decreased over the past three decades in southern California. Chromium fluxes were also lower in 2006 compared with the 1970s, although to a lesser extent than for lead. In contrast, copper and zinc fluxes were typically within the same order of magnitude between the two time periods, with some higher measurements observed in 2006 compared with the 1970s at the LAH and SDB sites. This result indicates atmospheric sources of copper and zinc have not decreased over the past three decades in southern California, and have increased near our harbor/urban sites. Differences in sampling conditions (e.g., Santa Ana winds) and measurement techniques may also explain, in part, the differences observed in metal flux rates for these time periods. However, these limitations were most important for those metals with the smallest difference in flux rates measured

  14. Atmospheric Deposition of Trace Elements in Ombrotrophic Peat as a Result of Anthropic Activities

    NASA Astrophysics Data System (ADS)

    Fabio Lourençato, Lucio; Cabral Teixeira, Daniel; Vieira Silva-Filho, Emmanoel

    2014-05-01

    Ombrotrophic peat can be defined as a soil rich in organic matter, formed from the partial decomposition of vegetable organic material in a humid and anoxic environment, where the accumulation of material is necessarily faster than the decomposition. From the physical-chemical point of view, it is a porous and highly polar material with high adsorption capacity and cation exchange. The high ability of trace elements to undergo complexation by humic substances happens due to the presence of large amounts of oxygenated functional groups in these substances. Since the beginning of industrialization human activities have scattered a large amount of trace elements in the environment. Soil contamination by atmospheric deposition can be expressed as a sum of site contamination by past/present human activities and atmospheric long-range transport of trace elements. Ombrotrophic peat records can provide valuable information about the entries of trace metals into the atmosphere and that are subsequently deposited on the soil. These trace elements are toxic, non-biodegradable and accumulate in the food chain, even in relatively low quantities. Thus studies on the increase of trace elements in the environment due to human activities are necessary, particularly in the southern hemisphere, where these data are scarce. The aims of this study is to evaluate the concentrations of mercury in ombrotrophic peat altomontanas coming from atmospheric deposition. The study is conducted in the Itatiaia National Park, Brazilian conservation unit, situated between the southeastern state of Rio de Janeiro, São Paulo and Minas Gerais. An ombrotrophic peat core is being sampled in altitude (1980m), to measure the trace elements concentrations of this material. As it is conservation area, the trace elements found in the samples is mainly from atmospheric deposition, since in Brazil don't exist significant lithology of trace elements. The samples are characterized by organic matter content which

  15. Atmospheric and Microbial Nitrate Contributions to Streams across a Regional Nitrogen Deposition Gradient

    NASA Astrophysics Data System (ADS)

    Rose, L.; Elliott, E. M.

    2014-12-01

    Chronically elevated atmospheric nitrate deposition has increased nitrate export from forests worldwide. This problem is particularly evident in the eastern U.S., where elevated stream nitrate concentrations and export from forested watersheds has led to the suggestion that some forests may be at or nearing a state of nitrogen saturation. To investigate the utility of nitrate stable isotopes in assessing the nitrogen saturation status of forests, we measured monthly δ15N, δ18O, Δ17O, and concentrations of nitrate in precipitation and stream water from reference watersheds at Coweeta (North Carolina), Fernow (West Virginia), and Hubbard Brook (New Hampshire) Experimental Forests from August 2012 to July 2013. Long-term mean nitrate deposition ranges from 11 kg ha-1 yr-1 to 17 kg ha-1 yr-1 and is significantly different (p<0.05) among the sites. Nitrate concentrations and isotopic compositions of precipitation did not differ significantly among the sites during the study. Seasonal trends in δ18O and Δ17O of nitrate values were also similar among sites, and were indicative of seasonal variation in dominant NOx oxidation pathway. The study sites differed significantly with respect to stream nitrate concentration (p<0.05) and isotopic composition (p<0.05). The high deposition site (Fernow) had the highest mean stream water nitrate concentration during the study period but the lowest percentages of atmospheric nitrate in monthly samples and on an annual average basis. In contrast, the low deposition site (Coweeta) had the lowest mean stream nitrate concentrations during the study and the highest mean percentage of atmospheric nitrate in the stream. Unprocessed atmospheric nitrate was also present in Coweeta stream samples during every month that isotope analyses were conducted for this site. Among these watersheds, stream nitrate concentration was negatively related to the proportion of unprocessed atmospheric nitrate in streams (R2=0.23; p<0.05). We will explore

  16. Monitoring Atmospheric Deposition of Nitrogen in Alpine Environments in Rocky Mountain and Yosemite National Parks, USA

    NASA Astrophysics Data System (ADS)

    Roop, H. A.; Clow, D. W.; Mills, J.; Fenn, M. E.

    2011-12-01

    Recent increases in atmospheric deposition of nitrogen (N) in the western U.S. have adversely impacted surface water quality and changed the composition of aquatic biota in high-elevation lakes. Existing N deposition data are generally not spatially diverse; representation of remote wilderness areas and high-elevation watersheds is often lacking, making it difficult to assess the importance of variations in N deposition on water quality impacts. This study aims to better understand N deposition in remote environments, particularly in alpine environments, where both the quantity and environmental impact of atmospheric N deposition are poorly understood. Understanding the impacts of N deposition on these environments is important for National Park resource and water-quality managers. Using ion-exchange resin (IER) collectors, seasonal through-fall of nitrogen was measured at 29 sites in the Rocky Mountains and 21 sites in the Sierra Nevada from 2006-2011. The IER collectors, deployed in pairs, represent geographically diverse transects aimed to quantify the spatial distribution of nitrogen deposition. Placed on talus slopes or in areas of exposed bedrock, the IER collectors were installed immediately following snowmelt (June/July) and replaced with new collectors prior to the first snowfall (September). Following spring melt, the collectors deployed over the winter were exchanged with new collectors. These seasonal swaps capture winter/spring and summer/fall deposition. A majority of the sites were paired with seasonal surface-water quality samples, allowing for comparison with nitrate levels in surface waters. In the lab, N compounds are eluted from the resins, then diluted and analyzed on an ion- chromatograph. Preliminary data from 2006, representing 16 sites with uncontaminated samples in Rocky Mountain National Park, suggest higher nitrogen deposition on the east side of the park. Average summer N deposition for an 85-day exposure period at the eastern slope

  17. ACIDIC DEPOSITION AND THE CORROSION AND DETERIORATION OF MATERIALS IN THE ATMOSPHERE: A BIBLIOGRAPHY, 1880-1982

    EPA Science Inventory

    The bibliography contains more than 1300 article citations and abstracts on the effects of acidic deposition, air pollutants, and biological and meteorological factors on the corrosion and deterioration of materials in the atmosphere. The listing includes citations for the years ...

  18. Temporal and Spatial Variation of Atmospherically Deposited Organic Contaminants at High Elevation in Yosemite National Park, California, USA

    EPA Science Inventory

    Atmospherically deposited organic contaminants in the Sierra Nevada mountains of California, USA, have exceeded some thresholds of concern, but the spatial and temporal distributions of contaminants in the mountains are not well known. The present study evaluated (1) whether the...

  19. Spatial Patterns of Atmospherically Deposited Organic Contaminants at High Elevation in the Southern Sierra Nevada Mountains, California

    EPA Science Inventory

    Atmospherically deposited contaminants in the Sierra Nevada mountains of California have been implicated as a factor adversely affecting biological resources such as amphibians and fish, yet the distributions of contaminants within the mountains are poorly known, particularly at...

  20. Spatial Patterns of Atmospherically Deposited Organic Contaminants at High Elevation in the Southern Sierra Nevada Mountains, California

    EPA Science Inventory

    Atmospherically deposited contaminants in the Sierra Nevada mountains of California have been implicated as adversely affecting amphibians and fish, yet the distributions of contaminants within the mountains are poorly known, particularly at high elevation. We tested the hypothe...

  1. Application of Ecosystem-Scale Fate and Bioaccumulation Models to Predict Fish Mercury Response Times to Changes in Atmospheric Deposition

    EPA Science Inventory

    Management strategies for controlling anthropogenic mercury emissions require understanding how ecosystems will respond to changes in atmospheric mercury deposition. Process-based mathematical models are valuable tools for informing such decisions, because measurement data often ...

  2. Empirical critical loads of atmospheric nitrogen deposition for nutrient enrichment and acidification of sensitive US lakes

    USGS Publications Warehouse

    Baron, J.S.; Driscoll, C.T.; Stoddard, J.L.; Richer, E.E.

    2011-01-01

    The ecological effects of elevated atmospheric nitrogen (N) deposition on high-elevation lakes of the western and northeastern United States include nutrient enrichment and acidification. The nutrient enrichment critical load for western lakes ranged from 1.0 to 3.0 kilograms (kg) of N per hectare (ha) per year, reflecting the nearly nonexistent watershed vegetation in complex, snowmelt-dominated terrain. The nutrient enrichment critical load for northeastern lakes ranged from 3.5 to 6.0 kg N per ha per year. The N acidification critical loads associated with episodic N pulses in waters with low values of acid neutralizing capacity were 4.0 kg N per ha per year (western) and 8.0 kg N per ha per year (northeastern). The empirical critical loads for N-caused acidification were difficult to determine because of a lack of observations in the West, and high sulfur deposition in the East. For both nutrient enrichment and acidification, the N critical load was a function of how atmospheric N deposition was determined. ?? 2011 by American Institute of Biological Sciences. All rights reserved.

  3. First national survey of atmospheric heavy metal deposition in Hungary by the analysis of mosses.

    PubMed

    Otvös, E; Pázmándi, T; Tuba, Z

    2003-06-20

    The atmospheric deposition of Cd, Cr, Cu, Fe, Ni, Pb, V and Zn in Hungary was investigated by using moss species as bioindicators. Our research was part of an international mapping project (Atmospheric Heavy Metal Deposition in Europe) [NORD 21 (1987) 1-44; NORD 9 (1994)] carried out in the most European countries in the 1990s to determine and to compare atmospheric heavy metal background pollution by standardized methods. Sampling was performed at 116 sites distributed over Hungary in the autumn of 1997. Moss species of Hypnum cupressiforme (72.4%) were preferred. But where it could not be collected, other species were taken. Unwashed, dried samples were digested with H(2)O(2)/HNO(3), and the concentrations of heavy metals were determined by ICP-AES. The results reflect local emission points. Background mean levels of Cd, Fe and Ni were mildly elevated in comparison to European means [NORD 9 (1994)]. Probably, that was due not only to pollution, but to the use of Hypnum cupressiforme, which can accumulate higher concentrations of heavy metals compared to other species. The results are presented on colored contour maps obtained with the SURFER program (Golden Software Inc. Co). PMID:12798100

  4. Nitrogen Isotopes in Tree Rings: A Record of Atmospheric Deposition or Tree Physiology?

    NASA Astrophysics Data System (ADS)

    Showers, W. J.; Genna, B.; Coon, M.

    2008-12-01

    Dendroisotopic analysis of nitrogen in tree rings has suggested that changes in nitrogen availability can be determined over time. These records match lake sediment and stream N flux measurements. Other studies suggest that tree ring nitrogen isotope data match foliar samples and not soil isotope data. In this study we compare the nitrogen isotope record from loblolly pine and American beech tree rings to a 10 year rainfall record and groundwater samples taken in isolated forested areas, next to a roadway and adjacent to agricultural fields. The influence of atmospheric nitrogen was determined by O17 analysis on groundwater nitrate. In areas where nutrient availability was low and O17 in groundwater nitrate was high, the tree ring nitrogen isotope record was similar to the nitrate nitrogen isotope trend. In areas where there was increased amounts of nitrate in groundwater due to local land use and O17 in groundwater nitrate was low, the nitrogen isotopic record in tree rings did not correlate to the atmospheric deposition record and probably represent internal recycling of nitrogen in the tree. These results suggest that nitrogen isotopes in tree rings can be used to monitor long term trends of atmospheric deposition of nitrogen in areas of low nutrient availability.

  5. Atmospheric Deposition of Organic Carbon in Pennsylvania as Affected by Climatic Factors

    NASA Astrophysics Data System (ADS)

    Iavorivska, L.; Boyer, E. W.; Grimm, J.; Fuentes, J. D.

    2014-12-01

    Organic matter which is usually expressed through measurements of dissolved organic carbon (DOC) is ubiquitous in atmospheric water. It plays an important role in cloud formation processes, and contributes to organic acidity of precipitation. Rain and snow deposited to the landscape is a source of nutrient enrichment to ecosystems and water bodies, and is especially important as an input of carbon in coastal regions. Since DOC is highly chemically reactive and bioavailable it influences rates of primary and secondary productivity in aquatic ecosystems. Despite the significance of DOC to many ecosystem processes, knowledge about its contributions to landscapes in precipitation remains limited. Here, we quantified the removal of DOC from the atmosphere via precipitation over space and time in order to assess the magnitude of wet deposition as a link between terrestrial and aquatic components of the carbon cycle. Further, we consider the predictability of organic matter in precipitation as a function of hydro-chemical and climatic variables. We measured DOC concentration and composition in storm events both sequentially (hourly during events) and seasonally (weekly over the year). Data on the chemical composition of precipitation, along with meteorological back-trajectory analyses help clarify how an interplay between emission sources, atmospheric transport and climatic conditions determine the abundance of rainwater DOC across Pennsylvania.

  6. Contribution of atmospheric deposition to tissue concentrations of mercury in aquatic bryophytes.

    PubMed

    Villares, Rubén; Díaz, Santiago; López, Jesús; Vázquez, Maria Dolores; Carballeira, Alejo

    2016-09-15

    In this biomonitoring study, we measured the temporal variations in concentrations of mercury in samples of aquatic bryophytes from rivers in a region that received large inputs of the metal via atmospheric deposition. In the first year of sampling, the presence of an important source of atmospheric deposition of Hg (a lignite-fired power plant) led, during the rainy season, to elevated concentrations of the metal in catchments situated downwind of the prevailing winds. High concentrations of the metal were even detected in samples from apparently clean rivers in isolated mountain sites within the downwind catchments. Substitution of the type of fuel (high quality imported carbon instead of brown coal) used in the power plant greatly reduced Hg emissions in subsequent years. Application of spatial interpolation techniques to dense monitoring networks with aquatic bryophytes, without taking into consideration the catchment borders, appears suitable for studying extensive atmospheric pollution derived from a large scale source of contamination. This study also demonstrates the importance of environmental specimen banks in retrospective studies of contamination, as they enable posterior analysis of contaminants that for various reasons cannot be analyzed at the time of sampling. PMID:27177131

  7. Atmospheric Mg2+ wet deposition within the continental United States and implications for soil inorganic carbon sequestration

    NASA Astrophysics Data System (ADS)

    Goddard, Megan A.; Mikhailova, Elena A.; Post, Christopher J.; Schlautman, Mark A.

    2007-02-01

    Little is known about atmospheric magnesium ion (Mg2+) wet deposition in relation to soil inorganic carbon sequestration. Understanding the conversion of carbon dioxide (CO2) or organic carbon to a form having a long residence time within the soil (e.g., dolomite, magnesian calcite) will greatly benefit agriculture, industry, and society on a global scale. This preliminary study was conducted to analyze atmospheric Mg2+ wet deposition within the continental United States (U.S.) and to rank the twelve major soil orders in terms of average annual atmospheric Mg2+ wet deposition. The total average annual Mg2+ wet deposition for each soil order was estimated with geographic information systems (GIS) using the following data layers: (1) atmospheric Mg2+ wet deposition data layers covering the continental U.S. for a 10-yr period (1994-2003) and (2) a soil order data layer derived from a national soils database. A map of average annual Mg2+ wet deposition for 1994-2003 reveals that the highest deposition (0.75-1.41 kg ha-1) occurred in Oregon, Washington, parts of California, and the coastal areas of East Coast states due to magnesium enrichment of atmospheric deposition from sea salt. The Midwestern region of the U.S. received about 0.25-0.75 kg ha-1 Mg2+ wet deposition annually, which was associated with loess derived soils, occurrence of dust storms and possibly fertilization. The soil orders receiving the highest average annual atmospheric Mg2+ wet deposition from 1994 to 2003 were: (1) Mollisols (3.7 × 107 kg), (2) Alfisols (3.6 × 107 kg) and (3) Ultisols (2.8 × 107 kg). In terms of potential soil carbon sequestration, the average annual atmospheric Mg2+ wet deposition was equivalent to formation of the following theoretical amounts of dolomite: (1) Mollisols (2.8 × 108 kg of CaMg(CO3)2), (2) Alfisols (2.7 × 108 kg of CaMg(CO3)2) and (3) Ultisols (2.1 × 108 kg of CaMg(CO3)2). The soil orders receiving the lowest average annual atmospheric Mg2+ wet deposition

  8. Mosses as an integrating tool for monitoring PAH atmospheric deposition: comparison with total deposition and evaluation of bioconcentration factors. A year-long case-study.

    PubMed

    Foan, Louise; Domercq, Maria; Bermejo, Raúl; Santamaría, Jesús Miguel; Simon, Valérie

    2015-01-01

    Polycyclic aromatic hydrocarbon (PAH) atmospheric deposition was evaluated at a remote site in Northern Spain using moss biomonitoring with Hylocomium splendens (Hedw.) Schimp., and by measuring the total deposition fluxes of PAHs. The year-long study allowed seasonal variations of PAH content in mosses to be observed, and these followed a similar trend to those of PAH fluxes in total deposition. Generally, atmospheric deposition of PAHs is greater in winter than in summer, due to more PAH emissions from domestic heating, less photoreactivity of the compounds, and intense leaching of the atmosphere by wet deposition. However, fractionation of these molecules between the environmental compartments occurs: PAH fluxes in total deposition and PAH concentrations in mosses are correlated with their solubility (r=0.852, p<0.01) and lipophilic properties (KOW, r=0.768, p<0.01), respectively. This annual study therefore showed that atmospheric PAH fluxes can be estimated with moss biomonitoring data if the bioconcentration or 'enriching' factors are known. PMID:25084064

  9. Atmospheric deposition of nitrogen, sulfur and base cations in jack pine stands in the Athabasca Oil Sands Region, Alberta, Canada.

    PubMed

    Fenn, M E; Bytnerowicz, A; Schilling, S L; Ross, C S

    2015-01-01

    Atmospheric deposition in the Athabasca Oil Sands Region decreased exponentially with distance from the industrial center. Throughfall deposition (kg ha(-1) yr(-1)) of NH(4)-N (.8-14.7) was double that of NO(3)-N (.3-6.7), while SO(4)-S ranged from 2.5 to 23.7. Gaseous pollutants (NO(2), HNO(3), NH(3), SO(2)) are important drivers of atmospheric deposition but weak correlations between gaseous pollutants and deposition suggest that particulate deposition is also important. The deposition (eq ha(-1)) of base cations (Ca + Mg + Na) across the sampling network was highly similar to N + S deposition, suggesting that acidic deposition is neutralized by base cation deposition and that eutrophication impacts from excess N may be of greater concern than acidification. Emissions from a large forest fire in summer 2011 were most prominently reflected in increased concentrations of HNO(3) and throughfall deposition of SO4-S at some sites. Deposition of NO(3)-N also increased as did NH(4)-N deposition to a lesser degree. PMID:25236261

  10. Characterisation of atmospheric deposition as a source of contaminants in urban rainwater tanks.

    PubMed

    Huston, R; Chan, Y C; Gardner, T; Shaw, G; Chapman, H

    2009-04-01

    To characterise atmospheric input of chemical contaminants to urban rainwater tanks, bulk deposition (wet+dry deposition) was collected at sixteen sites in Brisbane, Queensland, Australia on a monthly basis during April 2007-March 2008 (N=175). Water from rainwater tanks (22 sites, 26 tanks) was also sampled concurrently. The deposition/tank water was analysed for metals, soluble anions and selected samples were additionally analysed for PAHs, pesticides, phenols, organic & inorganic carbon. Flux (mg/m(2)/d) of total solids mass was found to correlate with average daily rainfall (R(2)=0.49) indicating the dominance of the wet deposition contribution to total solids mass. On average 97% of the total mass of analysed components was accounted for by Cl(-) (25.0%), Na (22.6%), organic carbon (20.5%), NO(3)(-) (10.5%), SO(4)(2-) (9.8%), inorganic carbon (5.7%), PO(4)(3-) (1.6%) and NO(2)(-) (1.5%). For other minor elements the average flux from highest to lowest was in the order of Fe>Al>Zn>Mn>Sr>Pb>Ba>Cu>Se. There was a significant effect of location on flux of K, Sb, Sn, Li, Mn, Fe, Cu, Zn, Ba, Pb and SO(4)(2-) but not other metals or anions. Overall the water quality resulting from the deposition (wet+dry) was good but 10.3%, 1.7% and 17.7% of samples had concentrations of Pb, Cd and Fe respectively greater than the Australian Drinking Water Guidelines (ADWG). This generally occurred in the drier months. In comparison 14.2% and 6.1% of tank samples had total Pb and Zn concentrations exceeding the guidelines. The cumulative mean concentration of lead in deposition was on average only 1/4 of that in tank water over the year at a site with high concentrations of Pb in tank water. This is an indication that deposition from the atmosphere is not the major contributor to high lead concentrations in urban rainwater tanks in a city with reasonable air quality, though it is still a significant portion. PMID:19171360

  11. The importance of source configuration in quantifying footprints of regional atmospheric sulphur deposition.

    PubMed

    Vieno, M; Dore, A J; Bealey, W J; Stevenson, D S; Sutton, M A

    2010-01-15

    An atmospheric transport-chemistry model is applied to investigate the effects of source configuration in simulating regional sulphur deposition footprints from elevated point sources. Dry and wet depositions of sulphur are calculated for each of the 69 largest point sources in the UK. Deposition contributions for each point source are calculated for 2003, as well as for a 2010 emissions scenario. The 2010 emissions scenario has been chosen to simulate the Gothenburg protocol emission scenario. Point source location is found to be a major driver of the dry/wet deposition ratio for each deposition footprint, with increased precipitation scavenging of SO(x) in hill areas resulting in a larger fraction of the emitted sulphur being deposited within the UK for sources located near these areas. This reduces exported transboundary pollution, but, associated with the occurrence of sensitive soils in hill areas, increases the domestic threat of soil acidification. The simulation of plume rise using individual stack parameters for each point source demonstrates a high sensitivity of SO(2) surface concentration to effective source height. This emphasises the importance of using site-specific information for each major stack, which is rarely included in regional atmospheric pollution models, due to the difficulty in obtaining the required input data. The simulations quantify how the fraction of emitted SO(x) exported from the UK increases with source magnitude, effective source height and easterly location. The modelled reduction in SO(x) emissions, between 2003 and 2010 resulted in a smaller fraction being exported, with the result that the reductions in SO(x) deposition to the UK are less than proportionate to the emission reduction. This non-linearity is associated with a relatively larger fraction of the SO(2) being converted to sulphate aerosol for the 2010 scenario, in the presence of ammonia. The effect results in less-than-proportional UK benefits of reducing in SO(2

  12. Atmospheric deposition of mercury in central Poland: Sources and seasonal trends

    NASA Astrophysics Data System (ADS)

    Siudek, Patrycja; Kurzyca, Iwona; Siepak, Jerzy

    2016-03-01

    Atmospheric deposition of total mercury was studied at two sites in central Poland, between April 2013 and October 2014. Hg in rainwater (bulk deposition) was analyzed in relation to meteorological parameters and major ions (H+, NO3-, Cl-, SO42 -) in order to investigate seasonal variation, identify sources and determine factors affecting atmospheric Hg chemistry and deposition. Total mercury concentrations varied between 1.24 and 22.1 ng L- 1 at the urban sampling site (Poznań) and between 0.57 and 18.3 ng L- 1 in the woodland protected area (Jeziory), with quite similar mean values of 6.96 and 6.37 ng L- 1, respectively. Mercury in precipitation exhibited lower spatial variability within the study domain (urban/forest transect) than the concentrations determined during other similar observations, reflecting the predominant influence of the same local sources. In our study, a significant seasonal pattern of Hg deposition was observed at both sampling sites, with higher and more variable concentrations of Hg reported for the urban area. In particular, deposition values of Hg were higher in the samples attributed to relatively large precipitation amounts in the summer and in those collected during the winter season (the result of higher contributions from combustion sources, i.e. intensive combustion of fossil fuels in residential and commercial boilers, individual power/heat-generating plants). In addition, a significant relationship between Hg concentration and precipitation amount was found while considering different types of wintertime samples (i.e. rain, snow and mixed precipitation). The analysis of backward trajectories showed that air masses arriving from polluted regions of western Europe and southern Poland largely affected the amount of Hg in rainwater. A seasonal variation in Hg deposition fluxes was also observed, with the maximum value of Hg in spring and minimum in winter. Our results indicated that rainwater Hg and, consequently, the wet deposition

  13. Trace-element evidence for the origin of desert varnish by direct aqueous atmospheric deposition

    NASA Astrophysics Data System (ADS)

    Thiagarajan, Nivedita; Aeolus Lee, Cin-Ty

    2004-07-01

    Smooth rock surfaces in arid environments are often covered with a thin coating of Fe-Mn oxyhydroxides known as desert varnish. It is debated whether such varnish is formed (a) by slow diagenesis of dust particles deposited on rock surfaces, (b) by leaching from the underlying rock substrate, or (c) by direct deposition of dissolved constituents in the atmosphere. Varnishes collected from smooth rock surfaces in the Mojave Desert and Death Valley, California are shown here to have highly enriched and fractionated trace-element abundances relative to upper continental crust (UCC). They are highly enriched in Co, Ni, Pb and the rare-earth elements (REEs). In particular, they have anomalously high Ce/La and low Y/Ho ratios. These features can only be explained by preferential scavenging of Co, Ni, Pb and the REEs by Fe-Mn oxyhydroxides in an aqueous environment. High field strength elements (HFSEs: Zr, Hf, Ta, Nb, Th), however, show only small enrichments despite the fact that these elements should also be strongly scavenged by Fe-Mn oxyhydroxides. This suggests that their lack of enrichment is a feature inherited from a solution initially poor in HFSEs. The first two scenarios for varnish formation can be ruled out as follows. The high enrichment factors of Fe, Mn and many trace elements cannot be generated by mass loss associated with post-depositional diagenesis of dust particles because such a process predicts only a small increase in concentration. In addition, the highly fractionated abundance patterns of particle reactive element pairs (e.g., Ce/La and Y/Ho) rules out leaching of the rock substrate. This is because if leaching were to occur, varnishes would grow from the inside to the outside, and thus any particle-reactive trace element leached from the substrate would be quantitatively sequestered in the Fe-Mn oxyhydroxide layers, prohibiting any significant elemental fractionations. One remaining possibility is that the Fe, Mn and trace metals in varnish are

  14. Modeling the Response of Terrestrial and Aquatic Ecosystems in the Northeastern U.S. to Changes in Atmospheric Deposition

    NASA Astrophysics Data System (ADS)

    Chen, L.; Driscoll, C. T.

    2003-12-01

    As a result of the Clean Air Act, atmospheric deposition of SO42- has declined significantly across the northeastern U.S. The acid-base status of many surface waters across the northeastern U.S. has significantly improved in response to these decreases. The response of soil and surface waters to changes in atmospheric deposition also varies among different subregions due to the different atmospheric deposition rates, soils, land use and other characteristics. In this study, an integrated biogeochemical model (PnET-BGC) was applied to 145 DDRP (Direct/Delayed Response Program) watersheds across the northeastern U.S. to simulate the changes in soil and surface waters in response to changes in atmospheric deposition at the regional scale. Sites of this study span across the Adirondacks, northern Pennsylvania/Catskills, northern New England, southern New England and Maine. The model simulated surface water chemistry was validated against synoptic surveys in 1984 and 2001. Preliminary modeling results indicated that besides the spatial gradients in S deposition, other factors such as wetland retention, seasalt impaction, land use, surficial and bedrock geology affect spatial variability in lake SO42- concentrations. In response to changes in atmospheric deposition, changes in lake SO42- concentrations were affected by amount of changes in S deposition and the ability of watersheds to retain SO42-. For sites in the Adirondacks and southern New England region, model predictions of changes in acid neutralizing capacity were consistent with measured changes.

  15. Comparison of atmospheric mercury speciation and deposition at nine sites across central and eastern North America

    NASA Astrophysics Data System (ADS)

    Engle, Mark A.; Tate, Michael T.; Krabbenhoft, David P.; Schauer, James J.; Kolker, Allan; Shanley, James B.; Bothner, Michael H.

    2010-09-01

    This study presents >5 cumulative years of tropospheric mercury (Hg) speciation measurements, over the period of 2003-2009, for eight sites in the central and eastern United States and one site in coastal Puerto Rico. The purpose of this research was to identify local and regional processes that impact Hg speciation and deposition (wet + dry) across a large swath of North America. Sites sampled were selected to represent both a wide range of mercury exposure and environmental conditions. Seasonal mean concentrations of elemental Hg (1.27 ± 0.31 to 2.94 ± 1.57 ng m-3; ? ± σ), reactive gaseous mercury (RGM; 1.5 ± 1.6 to 63.3 ± 529 pg m-3), and fine particulate Hg (1.2 ± 1.4 to 37.9 ± 492 pg m-3) were greatest at sites impacted by Hg point sources. Diel bin plots of Hgo and RGM suggest control by a variety of local/regional processes including impacts from Hg point sources and boundary layer/free tropospheric interactions as well as from larger-scale processes affecting Hg speciation (i.e., input of the global Hg pool, RGM formed from oxidation of Hgo by photochemical compounds at coastal sites, and elemental Hg depletion during periods of dew formation). Comparison of wet Hg deposition (measured), RGM and fine particulate Hg dry deposition (calculated using a multiple resistance model), and anthropogenic point source emissions varied significantly between sites. Significant correlation between emission sources and dry deposition was observed but was highly dependant upon inclusion of data from two sites with exceptionally high deposition. Findings from this study highlight the importance of environmental setting on atmospheric Hg cycling and deposition rates.

  16. External quality-assurance results for the National Atmospheric Deposition Program / National Trends Network and Mercury Deposition Network, 2004

    USGS Publications Warehouse

    Wetherbee, Gregory A.; Latysh, Natalie E.; Greene, Shannon M.

    2006-01-01

    The U.S. Geological Survey (USGS) used five programs to provide external quality-assurance monitoring for the National Atmospheric Deposition Program/National Trends Network (NADP/NTN) and two programs to provide external quality-assurance monitoring for the NADP/Mercury Deposition Network (NADP/MDN) during 2004. An intersite-comparison program was used to estimate accuracy and precision of field-measured pH and specific-conductance. The variability and bias of NADP/NTN data attributed to field exposure, sample handling and shipping, and laboratory chemical analysis were estimated using the sample-handling evaluation (SHE), field-audit, and interlaboratory-comparison programs. Overall variability of NADP/NTN data was estimated using a collocated-sampler program. Variability and bias of NADP/MDN data attributed to field exposure, sample handling and shipping, and laboratory chemical analysis were estimated using a system-blank program and an interlaboratory-comparison program. In two intersite-comparison studies, approximately 89 percent of NADP/NTN site operators met the pH measurement accuracy goals, and 94.7 to 97.1 percent of NADP/NTN site operators met the accuracy goals for specific conductance. Field chemistry measurements were discontinued by NADP at the end of 2004. As a result, the USGS intersite-comparison program also was discontinued at the end of 2004. Variability and bias in NADP/NTN data due to sample handling and shipping were estimated from paired-sample concentration differences and specific conductance differences obtained for the SHE program. Median absolute errors (MAEs) equal to less than 3 percent were indicated for all measured analytes except potassium and hydrogen ion. Positive bias was indicated for most of the measured analytes except for calcium, hydrogen ion and specific conductance. Negative bias for hydrogen ion and specific conductance indicated loss of hydrogen ion and decreased specific conductance from contact of the sample with

  17. Atmospheric phosphorus deposition at a montane site: Size distribution, effects of wildfire, and ecological implications

    NASA Astrophysics Data System (ADS)

    Vicars, William C.; Sickman, James O.; Ziemann, Paul J.

    2010-08-01

    The dry deposition of atmospheric particulate matter can be a significant source of phosphorus (P) to oligotrophic aquatic ecosystems, including high-elevation lakes. In this study, measurements of the mass concentration and size distribution of aerosol particles and associated particulate P are reported for the southern Sierra Nevada, California, for the period July-October, 2008. Coarse and fine particle samples were collected with Stacked Filter Units and analyzed for Total P (TP) and inorganic P (IP) using a digestion-extraction procedure, with organic P (OP) calculated by difference. Particle size-resolved mass and TP distributions were determined concurrently using a MOUDI cascade impactor. Aerosol mass concentrations were significantly elevated at the study site, primarily due to transport from offsite and emissions from local and regional wildfires. Atmospheric TP concentrations ranged from 11 to 75 ng m -3 (mean = 37 ± 16 ng m -3), and were typically dominated by IP. Phosphorus was concentrated in the coarse (>1 μm diameter) particle fraction and was particularly enriched in the 1.0-3.2 μm size range, which accounted for 30-60% of the atmospheric TP load. Wildfire emissions varied widely in P content, and may be related to fire intensity. The estimated dry depositional flux of TP for each daily sampling period ranged between 7 and 118 μg m -2 d -1, with a mean value of 40 ± 27 μg m -2 d -1. Relative rates of dry deposition of N and P in the Sierra Nevada are consistent with increasing incidence of N limitation of phytoplankton growth and previously observed long-term eutrophication of lakes.

  18. Cometary Delivery of Lunar Water: Transient Atmosphere Dynamics and Deposition Patterns

    NASA Astrophysics Data System (ADS)

    Prem, Parvathy; Artemieva, N. A.; Pierazzo, E.; Stewart, B. D.; Goldstein, D. B.; Varghese, P. L.; Trafton, L. M.

    2012-10-01

    Several missions have yielded observations that could indicate the presence of water ice in lunar polar regions. Our work aims to investigate cometary impacts as a mechanism for the delivery of water to permanently shadowed craters (‘cold traps’) at the lunar poles. Of particular interest is the influence of parameters such as impact angle, velocity and location on the long-term retention of cometary water. Our 3D, unsteady simulations use the SOVA hydrocode to model the impact and vaporization of a cometary nucleus composed of pure water ice, 2km in diameter, impacting at 30 km/s. Subsequently, a Direct Simulation Monte Carlo code, designed to handle rarefied planetary flows, is used to simulate the transient water vapor atmosphere that develops. Molecules in this atmosphere collide and migrate across the lunar surface, driven by diurnal variations in surface temperature, and may land in permanently shadowed craters, cold enough to trap water over geological time scales. Here, we discuss the dynamic development of the transient atmosphere and compare initial deposition patterns as gravitationally bound water vapor begins to fall back to the lunar surface, for two different impact angles: 45° and 60° from the horizontal. A greater fraction of water remains gravitationally bound to the Moon in the 60° case, and a less pronounced downrange focusing of the vapor results in a more symmetric initial deposition pattern. On the cold night-side of the Moon, water simply sticks to the surface. However, on the warm day-side, where residence times are much shorter, we observe the development of a relatively dense, low-speed, surface-hugging flow. A particularly interesting depositional feature is the concentration of mass at a point almost antipodal to the point of impact, where a convergence of streamlines results in a shock that channels water to the surface.

  19. Natural and anthropogenic variations in atmospheric mercury deposition during the Holocene near Quelccaya Ice Cap, Peru

    NASA Astrophysics Data System (ADS)

    Beal, Samuel A.; Kelly, Meredith A.; Stroup, Justin S.; Jackson, Brian P.; Lowell, Thomas V.; Tapia, Pedro M.

    2014-04-01

    Mercury (Hg) is a toxic metal that is transported globally through the atmosphere. Emissions of Hg from mineral reservoirs and recycling between soil/biomass, oceans, and the atmosphere are fundamental to the global Hg cycle, yet past emissions from anthropogenic and natural sources are not fully constrained. We use a sediment core from Yanacocha, a headwater lake in southeastern Peru, to study the anthropogenic and natural controls on atmospheric Hg deposition during the Holocene. From 12.3 to 3.5 ka, Hg fluxes in the record are relatively constant (mean ± 1σ: 1.4 ± 0.6 µg m-2 a-1). Past Hg deposition does not correlate with changes in regional temperature and precipitation or with most large volcanic events that occurred regionally (~300-400 km from Yanacocha) and globally. In 1450 B.C. (3.4 ka), Hg fluxes abruptly increased and reached the Holocene-maximum flux (6.7 µg m-2 a-1) in 1200 B.C., concurrent with a ~100 year peak in Fe and chalcophile metals (As, Ag, Tl) and the presence of framboidal pyrite. Continuously elevated Hg fluxes from 1200 to 500 B.C. suggest a protracted mining-dust source near Yanacocha that is identical in timing to documented pre-Incan cinnabar mining in central Peru. During Incan and Colonial time (A.D. 1450-1650), Hg deposition remains elevated relative to background levels but lower relative to other Hg records from sediment cores in central Peru, indicating a limited spatial extent of preindustrial Hg emissions. Hg fluxes from A.D. 1980 to 2011 (4.0 ± 1.0 µg m-2 a-1) are 3.0 ± 1.5 times greater than preanthropogenic fluxes.

  20. Levels of lead in atmospheric deposition in a large urban agglomeration in Poland.

    PubMed

    Polkowska, Z; Grynkiewicz, M; Górecki, T; Namieśnik, J

    2001-02-01

    Lead levels in wet and dry deposition were determined within this project. A network of 10 sampling stations was established. The stations were located in areas characterized by heavy traffic volumes, but away from industrial and/or municipal pollution sources. It was assumed, therefore, that lead in the samples collected was coming primarily from automobile emissions. Measurements were carried out over a period of one year. Both rain and snow samples were collected. Lead concentrations in the samples ranged from 0.6 to 141 microg dm(-3). They depended on street topography, traffic volume, average speed of the vehicles, frequency of traffic congestion and atmospheric conditions. The highest lead levels in deposition were observed during the cold season. PMID:11253008

  1. The effects of chronic nitrogen deposition on atmospheric biomass burning emissions

    NASA Astrophysics Data System (ADS)

    Asa-Awuku, A. A.; Giordano, M.; Weise, D.; Chang, J.

    2015-12-01

    This study examines how biomass burning emissions can be effected by regional air quality. An environmental chamber at the UC-Riverside Center for Environmental Research and Technology (CE-CERT) Atmospheric Processes Lab measured the properties of aerosols emitted from the burning of coniferous forest litter. Forest litter was collected from two sites of the San Bernardino Mountains Gradient Study in southern California: one site with high chronic nitrogen deposition rate and a site with low nitrogen deposition rate. The chemical and physical properties of the gas and aerosol-phase emissions were measured as a function of photochemical aging. Results indicate that there is a discernable compositional difference in the emissions from forest litter from an unpolluted (low NOx) environment as compared to a polluted (high NOx) environment. Fuel elemental analysis, NOx emission rates, aerosol volatility, and aerosol particle number distributions all differed significantly between the two sites.

  2. A model of the atmospheric metal deposition by cosmic dust particles

    NASA Astrophysics Data System (ADS)

    McNeil, W. J.

    1993-11-01

    We have developed a model of the deposition of meteoric metals in Earth's atmosphere. The model takes as input the total mass influx of material to the Earth and calculates the deposition rate at all altitudes through solution of the drag and subliminal equations in a Monte Carlo-type computation. The diffusion equation is then solved to give steady state concentration of complexes of specific metal species and kinetics are added to calculate the concentration of individual complexes. Concentrating on sodium, we calculate the Na(D) nightglow predicted by the model, and by introduction of seasonal variations in lower tropospheric ozone based on experimental results, we are able to duplicate the seasonal variation of mid-latitude nightglow data.

  3. Time Invariant Surface Roughness Evolution during Atmospheric Pressure Thin Film Depositions.

    PubMed

    Merkh, Thomas; Spivey, Robert; Lu, Toh Ming

    2016-01-01

    The evolution of thin film morphology during atmospheric pressure deposition has been studied utilizing Monte Carlo methods. Time invariant root-mean-squared roughness and local roughness morphology were both observed when employing a novel simulation parameter, modeling the effect of the experimental high pressure condition. This growth regime, where the surface roughness remains invariant after reaching a critical value, has not been classified by any existing universality class. An anti-shadowing growth mechanism responsible for this regime occurs when particles undergo binary collisions beneath the surface apexes. Hence, this mechanism is applicable when the mean free path of the depositing species is comparable to the amplitude of the surface features. Computationally this has been modeled by allowing particles to change direction at a specified height above the local film surface. This modification of the incoming flux trajectory consequently has a dramatic smoothening effect, and the resulting surfaces appear in agreement with recent experimental observations. PMID:26814165

  4. Atmospheric vapor phase deposition of nanometer-thick anti-stiction fluoropolymer coatings for silicon surfaces

    NASA Astrophysics Data System (ADS)

    Itoh, Shintaro; Takahashi, Kazuhiro; Morita, Hiroyuki; Fukuzawa, Kenji; Zhang, Hedong

    2016-06-01

    Anti-stiction coatings for silicon surfaces are a key technology to prevent the failure of nanoelectromechanical systems (NEMS) during operation and improve the forming accuracy in nanoimprint technology. In this study, we propose an atmospheric vapor phase deposition method to coat a silicon surface with fluoropolymers such as the perfluoropolyethers Fomblin Zdol 2000 and Zdol 4000. Thickness distributions, surface energies, coverages, and stiction forces for the deposited films were evaluated experimentally. The proposed method resulted in over 90% coverage with a film thickness of about 1 nm. The film thickness uniformity was around 0.1 nm over an area of 5 × 5 mm2. This coating effectively reduced the stiction forces by half compared with a bare silicon surface.

  5. Time Invariant Surface Roughness Evolution during Atmospheric Pressure Thin Film Depositions

    PubMed Central

    Merkh, Thomas; Spivey, Robert; Lu, Toh Ming

    2016-01-01

    The evolution of thin film morphology during atmospheric pressure deposition has been studied utilizing Monte Carlo methods. Time invariant root-mean-squared roughness and local roughness morphology were both observed when employing a novel simulation parameter, modeling the effect of the experimental high pressure condition. This growth regime, where the surface roughness remains invariant after reaching a critical value, has not been classified by any existing universality class. An anti-shadowing growth mechanism responsible for this regime occurs when particles undergo binary collisions beneath the surface apexes. Hence, this mechanism is applicable when the mean free path of the depositing species is comparable to the amplitude of the surface features. Computationally this has been modeled by allowing particles to change direction at a specified height above the local film surface. This modification of the incoming flux trajectory consequently has a dramatic smoothening effect, and the resulting surfaces appear in agreement with recent experimental observations. PMID:26814165

  6. Atmospheric mercury deposition recorded in an ombrotrophic peat core from Xiaoxing'an Mountain, Northeast China

    SciTech Connect

    Tang, Shunlin; Huang, Zhongwei; Liu, Jun; Yang, Zaichan; Lin, Qinhua

    2012-10-15

    The historical mercury accumulation rates (Hg AR) resulting from atmospheric deposition to Xiaoxing'an Mountain were determined via analysis of {sup 210}Pb- and {sup 14}C-dated cores up to 5000 years old. Natural Hg AR background, pre-industrial Hg AR and maximum industrial Hg AR in Northeast China were 2.2 {+-}1.0 {mu}g/m{sup 2}/yr for 5100-4500 BP, 5.7 {mu}g/m{sup 2}/yr and 112.4 {mu}g/m{sup 2}/yr, respectively. We assumed that the increase in Hg deposition in the Xiaoxing'an mountain area during industrial time was mainly attributed to local anthropogenic emissions around this peat bog.

  7. Atmospheric pressure spatial atomic layer deposition web coating with in situ monitoring of film thickness

    SciTech Connect

    Yersak, Alexander S.; Lee, Yung C.; Spencer, Joseph A.; Groner, Markus D.

    2014-01-15

    Spectral reflectometry was implemented as a method for in situ thickness monitoring in a spatial atomic layer deposition (ALD) system. Al{sub 2}O{sub 3} films were grown on a moving polymer web substrate at 100 °C using an atmospheric pressure ALD web coating system, with film growth of 0.11–0.13 nm/cycle. The modular coating head design and the in situ monitoring allowed for the characterization and optimization of the trimethylaluminum and water precursor exposures, purge flows, and web speed. A thickness uniformity of ±2% was achieved across the web. ALD cycle times as low as 76 ms were demonstrated with a web speed of 1 m/s and a vertical gap height of 0.5 mm. This atmospheric pressure ALD system with in situ process control demonstrates the feasibility of low-cost, high throughput roll-to-roll ALD.

  8. Aquatic Ecosystem Exposure Associated with Atmospheric Mercury Deposition: Importance of Watershed and Water Body Hot Spots and Hot Moments

    EPA Science Inventory

    Atmospheric deposition of divalent mercury (Hg(II)) is often the primary driving force for mercury contamination in fish tissue, resulting in mercury exposure to wildlife and humans. Transport and transformation of the deposited mercury into the environmentally relevant form, met...

  9. Seasonality of atmospheric nitrogen deposition at a semi-natural peatland site

    NASA Astrophysics Data System (ADS)

    Hurkuck, M.; Brümmer, C.; Kutsch, W. L.

    2012-04-01

    Large areas of natural peat bogs in Northwestern Germany have been converted to arable land and are characterised by decades of draining and peat cutting. Our study site - a semi-natural raised bog - is one of only very few remaining protected peatland areas. However, it is surrounded by highly fertilized agricultural land and poultry farms. In this study, we use a combined approach of independent methods to quantify seasonal variations of atmospheric nitrogen deposition most likely originated from agricultural practices. Concentrations and fluxes of ammonia and its atmospheric reactants are measured by a KAPS-denuder system integrated over one-week periods. Additionally, total nitrogen input from the atmosphere into a soil-plant model ecosystem is investigated by a 15N dilution method called 'Integrated Total Nitrogen Input' (ITNI). With this approach, we aim to allocate atmospheric nitrogen after its uptake by the ecosystem in aboveground biomass, roots and soil. First results from April to November 2011 show average ammonia concentrations ranging from 0.9 to 13.0 μg m-3. A first maximum of 8.8 μg m-3 could be observed in spring followed by relatively stable concentrations (mean: 3.7 μg m-3) in summer. Autumn ammonia concentrations reached a second peak of 13.0 μg m-3. By now, winter concentrations tend to be lower than those during the rest of the measuring period. Using the KAPS-denuder system within a gradient setup, deposition of ammonia was found to be between 0.08 to 0.25 kg NH3-N ha-1 week-1. The proportion of concentrations and fluxes of other N compounds such as HNO3, aerosol NH4 and NO3 was usually around 20 % of total measured nitrogen. During the first months of investigation, we found a total dry N deposition of about 5.4 kg ha-1. Extrapolation of data to one year amounts approximately to 9 kg ha-1 yr1. Our results suggest that the intensive agricultural land management of surrounding areas most likely leads to increasing N input into the

  10. Fabrication of transparent antifouling thin films with fractal structure by atmospheric pressure cold plasma deposition.

    PubMed

    Miyagawa, Hayato; Yamauchi, Koji; Kim, Yoon-Kee; Ogawa, Kazufumi; Yamaguchi, Kenzo; Suzaki, Yoshifumi

    2012-12-21

    Antifouling surface with both superhydrophobicity and oil-repellency has been fabricated on glass substrate by forming fractal microstructure(s). The fractal microstructure was constituted by transparent silica particles of 100 nm diameter and transparent zinc-oxide columns grown on silica particles by atmospheric pressure cold plasma deposition. The sample surface was coated with a chemically adsorbed monomolecular layer. We found that one sample has the superhydrophobic ability with a water droplet contact angle of more than 150°, while another sample has a high transmittance of more than 85% in a wavelength range from 400 to 800 nm. PMID:23186100

  11. Atmospheric pressure chemical vapor deposition of CdTe—reactor design considerations

    NASA Astrophysics Data System (ADS)

    Meyers, Peter V.; Kee, Robert J.; Raja, Laxminarayan; Wolden, Colin A.; Aire, Michael

    1999-03-01

    Atmospheric Pressure Chemical Vapor Deposition (APCVD) of polycrystalline thin-film CdTe appears to offer several practical advantages over state-of-the-art manufacturing techniques. APCVD employs the same reaction chemistry utilized to produce 16% efficient CdTe cells (i.e., same reaction chemistry as Close Spaced Sublimation), avoids use of vacuum equipment, allows for physical separation of the source and substrate, and employs forced convection to ensure uniform delivery of source material over large-area substrates. Reactor design considerations and preliminary numerical simulations of mass transport are presented.

  12. Assessment of nitrogen and phosphorus loading by atmospheric dry deposition to the Lagos Lagoon, Nigeria.

    PubMed

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

    2016-07-01

    Surface water pollution has been found to be considerably driven by the contributions of airborne particles, open-air waste burning and fossil fuel combustion, ammonia volatilization from excreta, fertilizer and derivatives from explosive factories. Atmospheric deposition into the Lagos Lagoon is suspected to be a major contributor to the nutrient levels of the lagoon. Atmospheric dry nutrient deposition was monitored at six stations around the Lagos Lagoon from January to June 2012 in order to estimate the contribution of atmospheric deposits into the lagoon's nutrient cycles. Species of phosphorus (P) and nitrogen (N) in the lagoon water were analyzed by colorimetric methods. Mean [NO(-) 3 + NO(-) 2]-N was 3.08 ± 2.10 mg m(-2) day(-1) (0.55-8.73 mg m(-2) day(-1)). The (NO(-) 3 + NO(-) 2)-N was only about 2 % of total N but [NH(+) 4 + organic]-N was approximately 38 % of total N. Particulate N was about 60 % of total N. Average total N was 144 ± 94.9 mg m(-2) day(-1) (48.0-285 mg m(-2) day(-1)). Average soluble reactive P was significantly lower than [NO(-) 3 + NO(-) 2]-N averaging about 0.12 ± 0.12 mg m(-2) day(-1). Soluble reactive P (SRP) was less than 2 % of total P but soluble organic P was about 86 % of total P. Particulate P accounted for about 12 % of total P. Average total P was 4.56 ± 10.1 mg m(-2) day(-1) (0.48-31.6 mg m(-2) day(-1)). This study shows that atmospheric deposition of nutrients into the Lagos Lagoon is taking place and this may represent a considerable proportion of the total nutrient loading of the lagoon. PMID:27325250

  13. Characteristics of modern atmospheric dust deposition in snow in the Mt. Yulong region, southeastern Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Niu, Hewen; He, Yuanqing; Lu, Xixi; Dong, Zhiwen; Zhao, Guoyong; Zhang, Tao; Du, Jiankuo

    2014-11-01

    We evaluated the concentration, size and distribution, and temporal variation of insoluble dust micro-particles in the snow, rainfall and water taken from the areas surrounding the Mt. Yulong to define the characteristics of modern atmospheric dust deposition and the contributions of different dust sources. The mean mass concentration (4511 μg kg-1) of micro-particles with 0.57 < d < 26 μm, and the diameter (11.5 μm) of dust contained in the water bodies of the Mt. Yulong are roughly similar to those observed in other sites, implying that dust is primarily supplied through short-range transport from proximal source regions (several or hundreds of km distances). The mean mass concentrations of micro-particles with 0.57 < d < 26 μm is lower in the rainfall than in the snow and the river water, suggesting the rain water is an ideal source/carrier for detecting the characteristics of modern atmospheric micro-particles. Volume size distributions of micro-particles in the snow and water showed single modal structures having volume median diameters from 3 to 26 μm. Number concentrations of micro-particles in the snow were higher than that in the rainfall, the river water contains the least amount of micro-particles. Vertical profiles of the snowpits show that there is a strong lateral correlation among the dust peaks, indicating a regional uniformity of dust deposition and suitability of snow analysis for dust deposition. In addition, the bare rock of snow-free terrain in the Mt. Yulong region and the mineral particles from local rock weathering are also important sources for the dust deposition.

  14. Background atmospheric sulfate deposition at a remote alpine site in the Southern Canadian Rocky Mountains

    NASA Astrophysics Data System (ADS)

    Wasiuta, Vivian; Norman, Ann-Lise; Lafrenière, Melissa J.; Hastings, Meredith G.

    2015-11-01

    We report observations of stable isotope ratios and ion concentrations from seasonal snowpack and summer bulk precipitation from remote alpine sites in the Southern Canadian Rocky Mountains. Spatial deposition patterns for sulfur (S) and δ34S-SO42- values indicate dominantly distant sources with little impact from local to regional pollution. Comparable S loads and total snowpack δ34S-SO42- values for glacier snowpack indicates S emissions were well mixed prior to dry deposition or incorporation into snowfall. A uniform S load and similar δ34S-SO42- values in a detailed study of summer bulk precipitation implies well-mixed distant emissions. We interpret the deposited 0.9 kg S ha-1yr-1 as atmospheric background deposition in midlatitude Western Canada. This study will improve calculations for sites impacted by point source emissions and provide a baseline for attributing changes associated with climate change, industrialization, and urban growth. Field evidence from this study supports theoretical and laboratory research on the relative importance of oxidation pathways on atmospheric δ34S-SO42- values for long-range transported sulfate. δ34S-SO42- of the dominant S source in summer bulk precipitation (~ +2‰) versus snowpack (≥ +9‰) cannot be explained by seasonal emission sources, temperature effects on fractionation, or Rayleigh distillation. The study supports a seasonal difference in the relative importance of the different SO2 to SO42- oxidation pathways with homogeneous oxidation by OH and heterogeneous oxidation by H2O2 most important in summer, and O2 catalyzed by transition metal ions in a radical chain reaction pathway more significant in winter.

  15. Effects of atmospheric deposition of energy-related pollutants on water quality: a review and assessment

    SciTech Connect

    Davis, M.J.

    1981-05-01

    The effects on surface-water quality of atmospheric pollutants that are generated during energy production are reviewed and evaluated. Atmospheric inputs from such sources to the aquatic environment may include trace elements, organic compounds, radionuclides, and acids. Combustion is the largest energy-related source of trace-element emissions to the atmosphere. This report reviews the nature of these emissions from coal-fired power plants and discusses their terrestrial and aquatic effects following deposition. Several simple models for lakes and streams are developed and are applied to assess the potential for adverse effects on surface-water quality of trace-element emissions from coal combustion. The probability of acute impacts on the aquatic environment appears to be low; however, more subtle, chronic effects are possible. The character of acid precipitation is reviewed, with emphasis on aquatic effects, and the nature of existing or potential effects on water quality, aquatic biota, and water supply is considered. The response of the aquatic environment to acid precipitation depends on the type of soils and bedrock in a watershed and the chemical characteristics of the water bodies in question. Methods for identifying regions sensitive to acid inputs are reviewed. The observed impact of acid precipitation ranges from no effects to elimination of fish populations. Coal-fired power plants and various stages of the nuclear fuel cycle release radionuclides to the atmosphere. Radioactive releases to the atmosphere from these sources and the possible aquatic effects of such releases are examined. For the nuclear fuel cycle, the major releases are from reactors and reprocessing. Although aquatic effects of atmospheric releases have not been fully quantified, there seems little reason for concern for man or aquatic biota.

  16. Comparative pick-up ion distributions at Mars and Venus: Consequences for atmospheric deposition and escape

    NASA Astrophysics Data System (ADS)

    Curry, Shannon M.; Luhmann, Janet; Ma, Yingjuan; Liemohn, Michael; Dong, Chuanfei; Hara, Takuya

    2015-09-01

    Without the shielding of a substantial intrinsic dipole magnetic field, the atmospheres of Mars and Venus are particularly susceptible to similar atmospheric ion energization and scavenging processes. However, each planet has different attributes and external conditions controlling its high altitude planetary ion spatial and energy distributions. This paper describes analogous test particle simulations in background MHD fields that allow us to compare the properties and fates, precipitation or escape, of the mainly O+ atmospheric pick-up ions at Mars and Venus. The goal is to illustrate how atmospheric and planetary scales affect the upper atmospheres and space environments of our terrestrial planet neighbors. The results show the expected convection electric field-related hemispheric asymmetries in both precipitation and escape, where the degree of asymmetry at each planet is determined by the planetary scale and local interplanetary field strength. At Venus, the kinetic treatment of O+ reveals a strong nightside source of precipitation while Mars' crustal fields complicate the simple asymmetry in ion precipitation and drive a dayside source of precipitation. The pickup O+ escape pattern at both Venus and Mars exhibits low energy tailward escape, but Mars exhibits a prominent, high energy 'polar plume' feature in the hemisphere of the upward convection electric field while the Venus ion wake shows only a modest poleward concentration. The overall escape is larger at Venus than Mars (2.1 ×1025 and 4.3 ×1024 at solar maximum, respectively), but the efficiency (likelihood) of O+ escaping is 2-3 times higher at Mars. The consequences of these comparisons for pickup ion related atmospheric energy deposition, loss rates, and detection on spacecraft including PVO, VEX, MEX and MAVEN are considered. In particular, both O+ precipitation and escape show electric field controlled asymmetries that grow with energy, while the O+ fluxes and energy spectra at selected spatial

  17. Atmospheric pressure glow discharge deposition of thermo-sensitive poly (N-isopropylacrylamide)

    NASA Astrophysics Data System (ADS)

    Shao, M.; Tang, X. L.; Wen, D.; Chen, Y.; Qiu, G.

    2013-12-01

    In this paper, a self-made atmospheric pressure dielectric barrier discharge reactor on intermediate frequency is brought forward and developed, which is equipped with power supply of 1-20 KHz, and the working gas is argon. The experimental results show that is a very stable and uniform atmospheric pressure glow discharge (APGD). Through a series of experiments, the waveforms of single pulse and multi-pulse glow discharge were both obtained. The voltage amplitude, discharge gap and dielectric material are studied, and the conditions of multi-pulse glow discharge are discussed as well. The novel methods of depositing poly (N-isopropylacrylamide) (PNIPAAm) coatings on the surface of glass slides and PS petri dish are provided by atmospheric pressure plasma polymerization. PNIPAAm can be obtained by plasma polymerization of N-isopropylacrylamide using the self-made equipment of atmospheric pressure plasma vapor treatment. The samples were characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and water contact angle. SEM analysis has revealed that the PNIPAAm coatings were formed on the surface of the smooth glass slides. Further evaluation by using XPS, it has shown the presence of PNIPAAm. The wettability can be significantly modified by changing of the temperatures at above and below of the lower critical solution temperature (LCST) from the data of the contact angle test. These results have advantage for further application on the thermo-sensitive textile materials.

  18. Impact of anthropogenic atmospheric nitrogen and sulfur deposition on ocean acidification and the inorganic carbon system.

    PubMed

    Doney, Scott C; Mahowald, Natalie; Lima, Ivan; Feely, Richard A; Mackenzie, Fred T; Lamarque, Jean-Francois; Rasch, Phil J

    2007-09-11

    Fossil fuel combustion and agriculture result in atmospheric deposition of 0.8 Tmol/yr reactive sulfur and 2.7 Tmol/yr nitrogen to the coastal and open ocean near major source regions in North America, Europe, and South and East Asia. Atmospheric inputs of dissociation products of strong acids (HNO(3) and H2SO(4)) and bases (NH(3)) alter surface seawater alkalinity, pH, and inorganic carbon storage. We quantify the biogeochemical impacts by using atmosphere and ocean models. The direct acid/base flux to the ocean is predominately acidic (reducing total alkalinity) in the temperate Northern Hemisphere and alkaline in the tropics because of ammonia inputs. However, because most of the excess ammonia is nitrified to nitrate (NO(3)(-)) in the upper ocean, the effective net atmospheric input is acidic almost everywhere. The decrease in surface alkalinity drives a net air-sea efflux of CO(2), reducing surface dissolved inorganic carbon (DIC); the alkalinity and DIC changes mostly offset each other, and the decline in surface pH is small. Additional impacts arise from nitrogen fertilization, leading to elevated primary production and biological DIC drawdown that reverses in some places the sign of the surface pH and air-sea CO(2) flux perturbations. On a global scale, the alterations in surface water chemistry from anthropogenic nitrogen and sulfur deposition are a few percent of the acidification and DIC increases due to the oceanic uptake of anthropogenic CO(2). However, the impacts are more substantial in coastal waters, where the ecosystem responses to ocean acidification could have the most severe implications for mankind. PMID:17804807

  19. Interactions between atmospheric circulation, nutrient deposition, and tropical forest primary production (Invited)

    NASA Astrophysics Data System (ADS)

    Randerson, J. T.; Chen, Y.; Rogers, B. M.; Morton, D. C.; van der Werf, G.; Mahowald, N. M.

    2010-12-01

    Tropical forests influence regional and global climate by means of several pathways, including by modifying surface energy exchange and by forming clouds. High levels of precipitation, leaching, and soil weathering limit nutrient availability in these ecosystems. Phosphorus (P) is a key element limiting net primary production, and in some areas, including forests recovering from prior disturbance, nitrogen (N) also may limit some components of production. Here we quantified atmospheric P and N inputs to these forests from fires using satellite-derived estimates of emissions and atmospheric models. In Africa and South America, cross-biome transport of fire-emitted aerosols and reactive N gases from savannas and areas near the deforestation frontier increased deposition of P and N in interior forests. Equatorward atmospheric transport during the dry (fire) season in one hemisphere was linked with surface winds moving toward the inter-tropical convergence zone (ITCZ) in the other hemisphere. Deposition levels were higher in tropical forests in Africa than in South America because of large savanna areas with high levels of fire emissions in both southern and northern Africa. We conclude by describing a potential feedback loop by which equatorward transport of fire emissions, dust, and spores sustains the productivity of tropical forests. We specifically assessed evidence that savanna-to-forest atmospheric transport of nutrients increases forest productivity, height, and rates of evapotranspiration (ET). In parallel, we examined the degree to which increases in ET and surface roughness in tropical forests have the potential to strengthen several components of the Hadley circulation, including deep convection, equatorward return flow (near the surface), and the intensity of seasonal drought in the subtropics (thereby increasing fires). These interactions are important for understanding biogeochemical - climate interactions on millennial timescales and for quantifying how

  20. Observations of Atmospheric Nitrogen and Phosphorus Deposition During the Period of Algal Bloom Formation in Northern Lake Taihu, China

    NASA Astrophysics Data System (ADS)

    Zhai, Shuijing; Yang, Longyuan; Hu, Weiping

    2009-09-01

    Cyanobacterial blooms in Lake Taihu occurred at the end of April 2007 and had crucial impacts on the livelihood of millions of people living there. Excessive nutrients may promote bloom formation. Atmospheric nitrogen (N) and phosphorus (P) deposition appears to play an important role in algal bloom formation. Bulk deposition and rain water samples were collected respectively from May 1 to November 30, 2007, the period of optimal algal growth, to measure the bulk atmospheric deposition rate, wet deposition rate, and dry deposition rate for total nitrogen (TN; i.e., all species of nitrogen), and total phosphorus (TP; i.e., all species of phosphorus), in northern Lake Taihu, China. The trends of the bulk atmospheric deposition rate for TN and the wet deposition rate for TN showed double peaks during the observation period and distinct influence with plum rains and typhoons. Meanwhile, monthly bulk atmospheric deposition rates for TP showed little influence of annual precipitation. However, excessive rain may lead to high atmospheric N and P deposition rates. In bulk deposition samples, the average percentage of total dissolved nitrogen accounting for TN was 91.2% and changed little with time. However, the average percentage of total dissolved phosphorus accounting for TP was 65.6% and changed substantially with time. Annual bulk atmospheric deposition rates of TN and TP during 2007 in Lake Taihu were estimated to be 2,976 and 84 kg km-2 a-1, respectively. The results showed decreases of 34.4% and 78.7%, respectively, compared to 2002-2003. Annual bulk deposition load of TN for Lake Taihu was estimated at 6,958 t a-1 in 2007 including 4,642 t a-1 of wet deposition, lower than the values obtained in 2002-2003. This may be due to measures taken to save energy and emission control regulations in the Yangtze River Delta. Nevertheless, high atmospheric N and P deposition loads helped support cyanobacterial blooms in northern Lake Taihu during summer and autumn, the period

  1. Atmospheric Transport and Deposition of Nitrogen Compounds From the Asian Continent Over the East China Sea

    NASA Astrophysics Data System (ADS)

    Uematsu, M.; Nakamura, T.; Endo, M.; Narita, Y.

    2004-12-01

    The growth of economy and population is rapid among in the east Asian countries. Within two decades, emission from east Asia could roughly account for half of the nitrogen released to the atmosphere from all anthropogenic sources worldwide. The Asia/western Pacific region has a unique mixture of aerosols and trace gases because of these distinctive patterns of emissions in combination with the local meteorological conditions affecting the region. Continental outflows can alter bilogical and chemical processes along the coastal Asia and, therefore, modify biogeochemical fluxes and feedbacks that may have serious implications to human health and climate implications. We made atmospheric measurements on board R/V Hakuho Maru over the western North Pacific and the East China Sea from 26 September to 9 October 2002 (the KH02-3 Cruise) in the autumn and from 4 to 20 March 2004 (the KH04-1 Cruise) in the spring. The atmospheric deposition fluxes of nitrogen compounds (ammonium, nitrate, and organic N) to the marine environment were investigated as a part of the IGBP/SOLAS project. Size segregated ambient aerosols (d<2.5μ m and d>2.5μ m) were collected at every 4-12 hours intervals on a PTFE fiber filter by using a high-volume dichotomous virtual impactor air sampler. Atmospheric average total ammonium concentration over the East China Sea was 2.3 μ g N m-3, and that of nitrate was 0.48 μ g N m-3. However, >90 percent of paticulate ammonium occurred in the fine fraction whereas >80 percent of particulate nitrate was in the coarse fraction. By using empirical dry deposition velocities for two size categories, we estimated the ammonium and nitrate dry deposition fluxes over the East China Sea to be 160 Gg N yr-1 and 270 Gg N yr-1, respectively. Our results clearly show that particle size is critical for different components and flux estimation. The atmospheric inputs of the nitrogen compounds to the East China Sea are found to be comparable to their fluxes of 190 Gg N yr

  2. Oxygen in the Martian atmosphere: Regulation of PO2 by the deposition of iron formations on Mars

    NASA Technical Reports Server (NTRS)

    Burns, Roger G.

    1992-01-01

    During Earth's early history, and prior to the evolution of its present day oxygenated atmosphere, extensive iron rich siliceous sedimentary rocks were deposited, consisting of alternating layers of silica (chert) and iron oxide minerals (hematite and magnetite). The banding in iron formations recorded changes of atmosphere-hydrosphere interactions near sea level in the ancient ocean, which induced the oxidation of dissolved ferrous iron, precipitation of insoluble ferric oxides and silica, and regulation of oxygen in Earth's early atmosphere. Similarities between the Archean Earth and the composition of the present day atmosphere on Mars, together with the pervasive presence of ferric oxides in the Martian regolith suggest that iron formation might also have been deposited on Mars and influenced the oxygen content of the Martian atmosphere. Such a possibility is discussed here with a view to assessing whether the oxygen content of the Martian atmosphere has been regulated by the chemical precipitation of iron formations on Mars.

  3. Deposition of atmospheric ions to pine branches and surrogate surfaces in the vicinity of emerald lake watershed, Sequoia National Park

    NASA Astrophysics Data System (ADS)

    Bytnerowicz, A.; Dawson, P. J.; Morrison, C. L.; Poe, M. P.

    Atmospheric dry deposition of ions to branches of native Pinus contorta and Pinus monticola (natural surfaces), and nylon filters and Whatman paper filters (surrogate surfaces) were measured in the summer of 1987 in the vicinity of Emerald Lake Watershed (ELW) of the Sequoia National Park located on the western slope of the Sierra Nevada in California. Deposition fluxes of airborne NO -3, NH +4 and SO 2-4 to native pines at the ELW were much higher than in the eastern Sierra Nevada, but several times lower than deposition fluxes to natural and surrogate surfaces at the highly polluted site in the San Gabriel Mountains of southern California. Deposition fluxes of NO 3- and NH 4+ to the natural and surrogate surfaces at the ELW were much higher than deposition of SO 42-, providing the importance of N compounds in atmospheric dry deposition in this part of the western U.S. A deficit of inorganic anions in materials deposited to various surfaces indicated a possibility of substantial participation of organic acids in atmospheric dry deposition processes. Nylon and paper filters proved to be poor surrogate surfaces for the estimation of ionic dry deposition to conifer branches.

  4. Deposition and Effects of Atmospheric Nitrogen and Ozone in Holm Oak Forests in Spain

    NASA Astrophysics Data System (ADS)

    González Fernández, I.; García Gómez, H.; Calvete Sogo, H.; Bermejo, V.; Valiño, F.; Elvira, S.; Rábago, I.; Sanz, J.; Alonso, R.

    2013-12-01

    Atmospheric nitrogen (N) emissions in Spain, in the western Mediterranean basin, have followed an increasing trend since 1990 and have only started to decline recently. These trends have resulted in growing N depositions in some areas and in N enrichment of ecosystems, as described in previous studies by increasing records of nitrophilous species in herbaria and raising N content both in bryophytes and in leaves of forest trees. Tropospheric ozone (O3) background concentrations, formed as a result of photochemical reactions of N compounds in the atmosphere, have also increased during the last decades. Despite these evidences, limited information is available on N and O3 deposition and effects in Holm oak forests, important ecosystems in Spain. New studies are being developed to address this lack of data. First results on N deposition in a Holm oak forest in central Spain stress the importance of seasonal variations of N inputs in Mediterranean environments. Spring and autumn rainfall events added up to 80% of total annual bulk deposition and losses of NO3- in the soil water were detected when throughfall N pulses occurred during periods of low plant physiological activity. N uptake in the tree canopy was also observed. High O3 concentrations were also measured in this study. The exposure to both N and O3 is a common situation in Holm oak forests. The combined effect of N and O3 deposition on the annual pasture of the Holm oak forest understory has been studied in an open-top chamber study using a simplified community of six species. Results show that O3 can potentially reduce pasture growth, decrease its nutritive value for herbivores and cause shifts in species abundance. N deposition can partially counterbalance O3-induced effects on the pasture biomass, thus both O3 and N need to be considered together when studying air pollution impacts in these ecosystems. The studies presented here are intended for developing N and O3 critical loads and levels for the

  5. Total Suspended Matter (TSM) and Maximum Signal Depth (Z90_max) for Monitoring the Evolution of Sediment Resuspension Process in Shallow Coastal Environments

    NASA Astrophysics Data System (ADS)

    Filipponi, Federico; Zucca, Francesco; Taramelli, Andrea; Valentini, Emiliana

    2015-12-01

    Monitoring sediment fluxes patterns in coastal area, like dispersion, sedimentation and resuspension processes, is a relevant topic for scientists, decision makers and natural resources management. Time series analysis of Earth Observation (EO) data may contribute to the understanding and the monitoring of processes in sedimentary depositional marine environment, especially for shallow coastal areas. This research study show the ability of optical medium resolution imagery to interpret the evolution of sediment resuspension from seafloor in coastal areas during intense wind forcings. Intense bora wind events in northern Adriatic Sea basin during winter season provoke considerable wave-generated resuspension of sediments, which cause variation in water column turbidity. Total Suspended Matter (TSM) product has been selected as proxy for qualitative and quantitative analysis of resuspended sediments. In addition, maximum signal depth (Z90_max), has been used to evaluate the evolution of sediment concentration in the water column.

  6. Photocatalytic Functional Coating of TiO2 Thin Film Deposited by Cyclic Plasma Chemical Vapor Deposition at Atmospheric Pressure

    NASA Astrophysics Data System (ADS)

    Kwon, Jung-Dae; Rha, Jong-Joo; Nam, Kee-Seok; Park, Jin-Seong

    2011-08-01

    Photocatalytic TiO2 thin films were prepared with titanium tetraisopropoxide (TTIP) using cyclic plasma chemical vapor deposition (CPCVD) at atmospheric pressure. The CPCVD TiO2 films contain carbon-free impurities up to 100 °C and polycrystalline anatase phases up to 200 °C, due to the radicals and ion-bombardments. The CPCVD TiO2 films have high transparency in the visible wavelength region and absorb wavelengths below 400 nm (>3.2 eV). The photocatalytic effects of the CPCVD TiO2 and commercial sprayed TiO2 films were measured by decomposing methylene blue (MB) solution under UV irradiation. The smooth CPCVD TiO2 films showed a relatively lower photocatalytic efficiency, but superior catalyst-recycling efficiency, due to their high adhesion strength on the substrates. This CPCVD technique may provide the means to produce photocatalytic thin films with low cost and high efficiency, which would be a reasonable candidate for practical photocatalytic applications, because of the reliability and stability of their photocatalytic efficiency in a practical environment.

  7. Atmospheric Pressure Spray Chemical Vapor Deposited CuInS2 Thin Films for Photovoltaic Applications

    NASA Technical Reports Server (NTRS)

    Harris, J. D.; Raffaelle, R. P.; Banger, K. K.; Smith, M. A.; Scheiman, D. A.; Hepp, A. F.

    2002-01-01

    Solar cells have been prepared using atmospheric pressure spray chemical vapor deposited CuInS2 absorbers. The CuInS2 films were deposited at 390 C using the single source precursor (PPh3)2CuIn(SEt)4 in an argon atmosphere. The absorber ranges in thickness from 0.75 - 1.0 micrometers, and exhibits a crystallographic gradient, with the leading edge having a (220) preferred orientation and the trailing edge having a (112) orientation. Schottky diodes prepared by thermal evaporation of aluminum contacts on to the CuInS2 yielded diodes for films that were annealed at 600 C. Solar cells were prepared using annealed films and had the (top down) composition of Al/ZnO/CdS/CuInS2/Mo/Glass. The Jsc, Voc, FF and (eta) were 6.46 mA per square centimeter, 307 mV, 24% and 0.35%, respectively for the best small area cells under simulated AM0 illumination.

  8. [Pollution Evaluation and Risk Assessment of Heavy Metals from Atmospheric Deposition in the Parks of Nanjing].

    PubMed

    Wang, Cheng; Qian, Xin; Li, Hui-ming; Sun, Yi-xuan; Wang, Jin-hua

    2016-05-15

    Contents of heavy metals involving As, Cd, Cr, Cu, Ni, Pb and Zn from atmospheric deposition in 10 parks of Nanjing were analyzed. The pollution level, ecological risk and health risk were evaluated using Geoaccumulation Index, Potential Ecological Risk Index and the US EPA Health Risk Assessment Model, respectively. The results showed that the pollution levels of heavy metals in Swallow Rock Park, Swallow Rock Park and Mochou Lake Park were higher than the others. Compared to other cities such as Changchun, Wuhan and Beijing, the contents of heavy metals in atmospheric deposition of parks in Nanjing were higher. The evaluation results of Geoaccumulation Index showed that Pb was at moderate pollution level, Zn and Cu were between moderate and serious levels, while Cd was between serious and extreme levels. The ecological risk level of Cd was high. The assessment results of Health Risk Assessment Model indicated that there was no non-carcinogenic risk for all the seven heavy metals. For carcinogenic risk, the risks of Cd, Cr and Ni were all negligible (Risk < 1 x 10⁻⁶), whereas As had carcinogenic risk possibility but was considered to be acceptable (10⁻⁶ < Risk < 10⁻⁴). PMID:27506017

  9. Atmospheric transport and deposition, an additional input pathway for triazine herbicides to surface waters

    SciTech Connect

    Muir, D.C.G.; Rawn, D.F.

    1996-10-01

    Although surface runoff from treated fields is regarded as the major route of entry of triazine herbicides to surface waters, other pathways such as deposition via precipitation, gas absorption and dryfall may also be important. Triazine herbicides have been detected in precipitation but there has been only a very limited amount of work on gas phase and aerosols. To examine the importance of atmospheric inputs concentrations of atrazine, cyanazine and terbuthylazine in gas phase/aerosols, precipitation, and surface waters were determined (along with other herbicides) using selected ion GC-MS. Atrazine was detected at low ng/L concentrations in surface waters (<0.04-5.3 ng/L) and precipitation (0.1-53 ng/L), and at 0.02-0.1 ng/m{sup 3} in air. Cyanazine and terbuthylazine were detected in air and infrequently in water. Highest atrazine concentrations in air were found during June each year on both gas phase and particles. Concentrations of atrazine in surface waters at both locations increased during June, even in the absence of precipitation or overland flow, presumably due to inputs from dryfall and to gas areas and boreal forest lakes due to transport and deposition. Ecological risk assessment of triazines, especially for pristine aquatic environments should include consideration of this atmospheric pathway.

  10. Atmospheric deposition of trace elements in Santiago de Querétaro city

    NASA Astrophysics Data System (ADS)

    Camacho Díaz, J. G.; González Sosa, E.; García Martínez, R.; Mondragón Olguín, V.; Miranda Castañeda, G.

    2013-05-01

    Atmospheric pollution and environment are one of the main problems around the planet. That's the reason which is important to understand the way pollution interact with weather. This work researches the contamination process from biological organisms or bio-indicators to identify and quantify those elements which are dangerous for humans. On one hand, because bio-indicators reduce cost for in situ monitoring systems and sample methods, and by the other hand because they can combine with isotopic analysis. Tilandsia Recurvata Liquens (Bromeliaceae) were collected in urban zone from Santiago de Querétaro, establishing 2 sample periods, which are April - June 2011 and March - April 2012. Total number of samples was 190 from 14 sites, 100 corresponding for first period and 90 for the second. Also, reference samples were collected from a place located at 30 km from metropolitan area. Element concentrations were determined through isotopy for 13C y 15N and metal elements by using and ICP-MS. Maps were drawn to explain distribution and deposition in the city to distinguish natural contribution and anthropogenic deposition. 13C y 15N results showed that distribution of carbon and nitrogen compound is conditioned due vehicular traffic activity, wind frequency and rain patterns. Key Words: Bio-monitoring, bio-indicator, liquen, atmospheric pollution, isotopy, ICP-MS Analysis.

  11. Dietary intake of pollutant aerosols via vegetables influenced by atmospheric deposition and wastewater irrigation.

    PubMed

    Pandey, Richa; Shubhashish, Kumar; Pandey, Jitendra

    2012-02-01

    Pot culture experiments were conducted to study dietary intake of heavy metals via vegetables, spinach (Spinacia oleracea L.), radish (Raphanus sativus L.) and tomato (Lycopersicon esculentum Mill) grown under the influence of atmospheric deposition and wastewater irrigation. The results indicated substantial accumulation of heavy metals in vegetables, which contribute significantly to dietary intake of total heavy metals ranging from 1.34 to 110.40 μg g⁻¹ through leaves (spinach), 1.04 to 105.86 μg g⁻¹ through root (radish) and 0.608 to 82.19 μg g⁻¹ through fruits (tomato). Concentration of Cd, Ni and Pb in vegetables exceeded the safe limits of Prevention of Food Adulteration Act 1954. Health risk index for Cd and Pb exceeded the safe limits set by the United States Environmental Protection Agency. The study indicated that the atmospheric depositions as well as wastewater irrigation have significantly elevated the levels of heavy metals in dietary vegetables presenting a significant threat for the health of users. PMID:22019253

  12. Cadmium contamination in Tianjin agricultural soils and sediments: relative importance of atmospheric deposition from coal combustion.

    PubMed

    Wu, Guanghong; Yang, Cancan; Guo, Lan; Wang, Zhongliang

    2013-06-01

    Cadmium (Cd) in coal, fly ash, slag, atmospheric deposition, soils and sediments collected from Tianjin, northern China, were measured to provide baseline information and determine possible Cd sources and potential risk. The concentrations of Cd in coal, fly ash and atmospheric deposition were much higher than the soil background values. Fallout from coal-fired thermal power plants, heating boilers and industrial furnaces has increased the Cd concentration in soils and sediments in Tianjin. The concentrations of Cd in soils of suburban areas were significantly higher than in rural areas, suggesting that coal burning in Tianjin may have an important impact on the local physical environment. Cd from coal combustion is readily mobilized in soils. It is soluble and can form aqueous complexes and permeate river sediments. The high proportion of mobile Cd affects the migration of Cd in soils and sediments, which may pose an environmental threat in Tianjin due to the exposure to Cd and Cd compounds via the food chain. This study may provide a window for understanding and tracing sources of Cd in the local environment and the risk associated with Cd bioaccessibility. PMID:23212535

  13. Future monitoring of charged particle energy deposition into the upper atmosphere and comments on possible relationships between atmospheric phenomena and solar and/or geomagnetic activity

    NASA Technical Reports Server (NTRS)

    Williams, D. J.; Grubb, R. N.; Evans, D. S.; Sauer, H. H.

    1974-01-01

    The charged particle observations proposed for the new low altitude weather satellites, TIROS-N, are described that will provide the capability of routine monitoring of the instantaneous total energy deposition into the upper atmosphere by the precipitation of charged particles from higher altitudes. Estimates are given to assess the potential importance of this type of energy deposition. Discussion and examples are presented illustrating the importance in distinguishing between solar and geomagnetic activity as possible causative sources.

  14. [The deposition of tritium in form of HTO from atmosphere moisture to Hypogymnia physodes lichens during chamber experiments].

    PubMed

    Golubeva, V N; Golubev, A V; Kosheleva, T A; Kuznetsova, V F; Mavrin, S V

    2008-01-01

    The results of the deposition of tritium oxide (HTO) from atmosphere to Hypogymnia physodes lichens during chamber experiments are presented. For lichens the content of tissue water tritium (TWT) and organically bound tritium (OBT) were measuremed. Were shown that lichens mainly absorb HTO from atmosphere during first 24 hours. The ratio TWT/HTO of chamber and the velocity of TWT to OBT conversion in lichens were determined. Was noted that the TWT to OBT conversion velocity for lichens is ten times greater than that for deposition of HTO by vascular plant leafs. There was supposed that TWT to OCT conversion in lichens is occurred through alga as well as fungus component of lichens. The intensive deposition HTO from chamber atmosphere by lichens and high velocity of HTO to OBT conversion show the availability to use lichens for determination of atmosphere pollution by HTO. PMID:19004335

  15. Nitrogen Transport from Atmospheric Deposition and Contaminated Groundwater to Surface Waters on a Watershed Scale.

    NASA Astrophysics Data System (ADS)

    Showers, W. J.; Demaster, D.

    2005-12-01

    Increasing nitrate contamination of surface water and groundwater is a problem in regions of intensive agriculture and near urban wastewater treatment facilities that land-apply biosolids. The 15N composition of groundwater nitrate has been used to assess potential sources of nitrogen contamination. But because of transformations of nitrogen within the hydrological system, contaminant source tracing with nitrogen isotopes has been complicated. We have used multiple isotope tracers of nitrate (15N, 17O, 18O) to distinguish between different N contamination sources, areas of extensive denitrification, and areas of atmospheric N deposition on the NC coastal plain and piedmont. Areas of extensive denitrification are often associated with hydric soils. The distribution of hydric soils on field and watershed scales correlates with surface and ground water quality degradation. The distribution of hydric soils may thus be an important element in prediction of environmental impacts of agriculture. Transport of atmospheric nitrogen into surface waters as indicated by the 17O of nitrate is event driven. Most surface waters in our study area have low concentrations of nitrate 17O, indicating that the importance of atmospheric N has been overestimated in riverine N flux from watersheds. However, when the atmospheric N flux is integrated over a discharge event, atmospheric N can approach 25 % of the total N riverine flux in urban areas. More work needs to be completed with multiple isotopic tracers and GIS analysis on watershed scales. Using a GIS / isotope approach, areas where the isotopic signature has been affected by denitrification can be predicted, and remediation efforts can be focused on potential areas of N contamination where extensive denitrification is unlikely to occur.

  16. Atmospheric occurrence and deposition of hexachlorobenzene and hexachlorocyclohexanes in the Southern Ocean and Antarctic Peninsula

    NASA Astrophysics Data System (ADS)

    Galbán-Malagón, Cristóbal; Cabrerizo, Ana; Caballero, Gemma; Dachs, Jordi

    2013-12-01

    Despite the distance of Antarctica and the Southern Ocean to primary source regions of organochlorine pesticides, such as hexachlorobenzene (HCB) and hexachlorocyclohexanes (HCHs), these organic pollutants are found in this remote region due to long range atmospheric transport and deposition. This study reports the gas- and aerosol-phase concentrations of α-HCH, γ-HCH, and HCB in the atmosphere from the Weddell, South Scotia and Bellingshausen Seas. The atmospheric samples were obtained in two sampling cruises in 2008 and 2009, and in a third sampling campaign at Livingston Island (2009) in order to quantify the potential secondary sources of HCHs and HCB due to volatilization from Antarctic soils and snow. The gas phase concentrations of HCHs and HCB are low, and in the order of very few pg m-3 α-HCH and γ-HCH concentrations were higher when the air mass back trajectory was coming from the Antarctic continent, consistent with net volatilization fluxes of γ-HCH measured at Livingston Island being a significant secondary source to the regional atmosphere. In addition, the Southern ocean is an important net sink of HCHs, and to minor extent of HCB, due to high diffusive air-to-water fluxes. These net absorption fluxes for HCHs are presumably due to the role of bacterial degradation, depleting the water column concentrations of HCHs in surface waters and driving an air-water disequilibrium. This is the first field study that has investigated the coupling between the atmospheric occurrence of HCHs and HCB, the simultaneous air-water exchange, soil/snow-air exchange, and long range transport of organic pollutants in Antarctica and the Southern Ocean.

  17. Atmospheric deposition and solute export in giant sequoia: mixed conifer watersheds in the Sierra Nevada, California

    USGS Publications Warehouse

    Stohlgren, Thomas J.; Melack, John M.; Esperanza, Anne M.; Parsons, David J.

    1991-01-01

    Atmospheric depostion and stream discharge and solutes were measured for three years (September 1984 - August 1987) in two mixed conifer watersheds in Sequoia National Park, in the southern Sierra Nevada of California. The Log Creek watershed (50 ha, 2067-2397 m elev.) is drained by a perennial stream, while Tharp's Creek watershed (13 ha, 2067-2255 m elev.) contains an intermittent stream. Dominant trees in the area include Abies concolor (white fir), Sequoiadendron giganteum (giant sequoia), A. magnifica (red fir), and Pinus lambertiana (sugar pine). Bedrock is predominantly granite and granodiorite, and the soils are mostly Pachic Xerumbrepts. Over the three year period, sulfate (SO42-), nitrate (NO3-), and chloride (Cl-) were the major anions in bulk precipitation with volume-weighted average concentrations of 12.6, 12.3 and 10.0 μeq/1, respectively. Annual inputs of NO3-N, NH4-N and SO4-S from wet deposition were about 60 to 75% of those reported from bulk deposition collectors. Discharge from the two watersheds occurs primarily during spring snowmelt. Solute exports from Log and Tharp's Creeks were dominated by HCO3-, Ca2+ and Na+, while H+, NO3-, NH4+ and PO43- outputs were relatively small. Solute concentrations were weakly correlated with instantaneous stream flow for all solutes (r2 3- (Log Cr. r2=0.72; Tharp's Cr. r2=0.38), Na+ (Log Cr. r2=0.56; Tharp's Cr. r2=0.47), and silicate (Log Cr. r2=0.71; Tharp's Cr. r2=0.49). Mean annual atmospheric contributions of NO3-N (1.6 kg ha-1), NH4-N (1.7 kg ha-1), and SO4-S (1.8 kg ha-1), which are associated with acidic deposition, greatly exceed hydrologic losses. Annual watershed yields (expressed as eq ha-1) of HCO3- exceeded by factors of 2.5 to 37 the annual atmospheric deposition of H+.

  18. Historical deposition of persistent organic pollutants in Lake Victoria and two alpine equatorial lakes from East Africa: Insights into atmospheric deposition from sedimentation profiles.

    PubMed

    Arinaitwe, Kenneth; Rose, Neil L; Muir, Derek C G; Kiremire, Bernard T; Balirwa, John S; Teixeira, Camilla

    2016-02-01

    Information on historical deposition of persistent organic pollutants (POPs) for African lakes is very limited. We investigated historical deposition trends and sources of POPs in sediment cores from Lakes Victoria (SC1), Bujuku (Buju2) and Mahoma (Maho2). The latter two lakes are situated in the Rwenzori mountain range in western Uganda. SC1 was taken from a central depositional area within the Ugandan part of the lake. Profiles in Buju2 and Maho2 were used as a reference for historical atmospheric deposition. For the post-1940 sediment deposits in SC1, average focusing factor-adjusted fluxes (FFFs) of ΣDDTs, polychlorinated biphenyls (ΣPCBs), hexachlorocyclohexanes (ΣHCHs) and chlordanes (ΣCHLs) were 390, 230, 210 and 120 ng m(-2) yr(-1). Higher fluxes of ΣDDTs, ΣPCBs, and ΣCHLs were observed in Buju2 and Maho2. The average FFF of HCB in Buju2 was the highest while the values for Maho2 and SC1 were similar. The endosulfan FFFs in SC1 were lower than in the alpine lake cores. Generally, Buju2 was a better reference for historical atmospheric deposition of POPs than Maho2 probably due to distortion of the latter's profile by Lake Mahoma's forested catchment. Profiles of p,p'-DDE, ΣCHLs and HCB in SC1 were consistent with atmospheric deposition while profiles of PCBs and HCHs were indicative of particle-bound loadings from additional sources. Profiles of endosulfans, DDTs, and chlordanes were consistent with influence of other factors such as anoxia, and dilution. Further studies of spatial resolution of historical deposition, especially in near-shore deposition areas of the lake are recommended. PMID:26539705

  19. An Evaluation of Atmospheric-pressure Plasma for the Cost-Effective Deposition of Antireflection Coatings

    SciTech Connect

    Rob Sailer; Guruvenket Srinivasan; Kyle W. Johnson; Douglas L. Schulz

    2010-04-01

    Atmospheric-pressure plasma deposition (APPD) has previously been used to deposit various functional materials including polymeric surface modification layers, transparent conducting oxides, and photo catalytic materials. For many plasma polymerized coatings, reaction occurs via free radical mechanism where the high energy electrons from the plasma activate the olefinic carbon-carbon double bonds - a typical functional group in such precursors. The precursors for such systems are typically inexpensive and readily available and have been used in vacuum PECVD previously. The objectives are to investigate: (1) the effect of plasma power, gas composition and substrate temperature on the Si-based film properties using triethylsilane(TES) as the precursor; and (2) the chemical, mechanical, and optical properties of several experimental matrices based on Design of Experiment (DOE) principals. A simple APPD route has been utilized to deposit Si based films from an inexpensive precursor - Triethylsilane (TES). Preliminary results indicates formation of Si-C & Si-O and Si-O, Si-C & Si-N bonds with oxygen and nitrogen plasmas respectively. N{sub 2}-O{sub 2} plasma showed mixed trend; however oxygen remains a significant portion of all films, despite attempts to minimize exposure to atmosphere. SiN, SiC, and SiO ratios can be modified by the reaction conditions resulting in differing film properties. SE studies revealed that films with SiN bond possess refractive index higher than coatings with Si-O/Si-C bonds. Variable angle reflectance studies showed that SiOCN coatings offer AR properties; however thickness and refractive index optimization of these coatings remains necessary for application as potential AR coatings.

  20. Atmospheric deposition and storm induced runoff of heavy metals from different impermeable urban surfaces.

    PubMed

    Wicke, Daniel; Cochrane, Thomas A; O'Sullivan, Aisling D

    2012-01-01

    Contaminants deposited on impermeable surfaces migrate to stormwater following rainfall events, but accurately quantifying their spatial and temporal yields useful for mitigation purposes is challenging. To overcome limitations in current sampling methods, a system was developed for rapid quantification of contaminant build-up and wash-off dynamics from different impervious surfaces. Thin boards constructed of concrete and two types of asphalt were deployed at different locations of a large carpark to capture spatially distributed contaminants from dry atmospheric deposition over specified periods of time. Following experimental exposure time, the boards were then placed under a rainfall simulator in the laboratory to generate contaminant runoff under controlled conditions. Single parameter effects including surface roughness and material composition, number of antecedent dry days, rain intensity, and water quality on contaminant build-up and wash-off yields could be investigated. The method was applied to quantify spatial differences in deposition rates of contaminants (TSS, zinc, copper and lead) at two locations varying in their distance to vehicle traffic. Results showed that boards exposed at an unused part of the carpark >50 m from vehicular traffic captured similar amounts of contaminants compared with boards that were exposed directly adjacent to the access route, indicating substantial atmospheric contaminant transport. Furthermore, differences in contaminant accumulation as a function of surface composition were observed. Runoff from asphalt boards yielded higher zinc loads compared with concrete surfaces, whereas runoff from concrete surfaces resulted in higher TSS concentrations attributed to its smoother surfaces. The application of this method enables relationships between individual contaminant behaviour and specific catchment characteristics to be investigated and provides a technique to derive site-specific build-up and wash-off functions required

  1. Changes in atmospheric nitrate deposition in Germany--an isotopic perspective.

    PubMed

    Beyn, Fabian; Matthias, Volker; Dähnke, Kirstin

    2014-11-01

    We investigated the isotopic composition of atmospheric NO3(-) deposition at a moderately polluted site in Western Europe over an annual cycle from December 2011 to November 2012. On average, we measured load-weighted δ(15)N values of +0.1 and +3.0‰ in wet and dry deposition, respectively. A comparison to source-specific N emission trends and to isotope data from the 1980s reveals distinct changes in δ(15)N-NO3(-) values: In contrast to the increasing relative importance of isotopically depleted natural NOx sources, we find an increase of isotope values in comparison to historical data. We explore the role of land-based N sources, because backward trajectories reveal a correlation of higher δ(15)N to air mass origin from industrialized areas. Nowadays isotopically enriched NOx of coal-fired power plants using selective catalytic converters and land-based vehicle emissions, which use same technology, are apparently the main driver of rising δ(15)N values in nitrate deposition. PMID:25078659

  2. Characterisation of nano-crystalline titanium dioxide films grown by atmospheric pressure plasma electrolytic deposition

    NASA Astrophysics Data System (ADS)

    Paulmier, Thierry; Bell, John M.; Fredericks, Peter M.

    2006-01-01

    A new atmospheric pressure plasma electrolytic process has been developed for the deposition of TiO II crystalline thin films on metal substrate. Contrary to the other deposition techniques, the process occurs in a liquid precursor, composed of titanium tetraisopropoxide and absolute ethanol. A plasma discharge is created and confined around the cathode in a superheated vapour sheath surrounded by the liquid phase, inducing the production of a thin TiO II coating at the surface of the cathode. Because of the flexibility of the operating parameters, this technology allows the rapid deposition of thin films with a wide range of structural and physical properties. This process enables therefore the production of nanocrystalline titania films with adjustable morphology and structure (anatase, rutile) by adjusting the operating voltage, current intensity, the treatment time and calcination temperature. The analysis of the structure and composition of these TiO II coatings have been carried out by Scanning Electron Microscopy, Transmission Electron Microscopy, Raman spectroscopy, X-ray Photoelectron Spectroscopy and X-Ray Diffraction. A thorough study has been performed to understand the influence of the operating parameters on the properties and structure of the coatings.

  3. Diamond synthesis at atmospheric pressure by microwave capillary plasma chemical vapor deposition

    SciTech Connect

    Hemawan, Kadek W.; Gou, Huiyang; Hemley, Russell J.

    2015-11-02

    Polycrystalline diamond has been synthesized on silicon substrates at atmospheric pressure, using a microwave capillary plasma chemical vapor deposition technique. The CH{sub 4}/Ar plasma was generated inside of quartz capillary tubes using 2.45 GHz microwave excitation without adding H{sub 2} into the deposition gas chemistry. Electronically excited species of CN, C{sub 2}, Ar, N{sub 2}, CH, H{sub β}, and H{sub α} were observed in the emission spectra. Raman measurements of deposited material indicate the formation of well-crystallized diamond, as evidenced by the sharp T{sub 2g} phonon at 1333 cm{sup −1} peak relative to the Raman features of graphitic carbon. Field emission scanning electron microscopy images reveal that, depending on the growth conditions, the carbon microstructures of grown films exhibit “coral” and “cauliflower-like” morphologies or well-facetted diamond crystals with grain sizes ranging from 100 nm to 10 μm.

  4. Modeling chemical vapor deposition of silicon dioxide in microreactors at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Konakov, S. A.; Krzhizhanovskaya, V. V.

    2015-01-01

    We developed a multiphysics mathematical model for simulation of silicon dioxide Chemical Vapor Deposition (CVD) from tetraethyl orthosilicate (TEOS) and oxygen mixture in a microreactor at atmospheric pressure. Microfluidics is a promising technology with numerous applications in chemical synthesis due to its high heat and mass transfer efficiency and well-controlled flow parameters. Experimental studies of CVD microreactor technology are slow and expensive. Analytical solution of the governing equations is impossible due to the complexity of intertwined non-linear physical and chemical processes. Computer simulation is the most effective tool for design and optimization of microreactors. Our computational fluid dynamics model employs mass, momentum and energy balance equations for a laminar transient flow of a chemically reacting gas mixture at low Reynolds number. Simulation results show the influence of microreactor configuration and process parameters on SiO2 deposition rate and uniformity. We simulated three microreactors with the central channel diameter of 5, 10, 20 micrometers, varying gas flow rate in the range of 5-100 microliters per hour and temperature in the range of 300-800 °C. For each microchannel diameter we found an optimal set of process parameters providing the best quality of deposited material. The model will be used for optimization of the microreactor configuration and technological parameters to facilitate the experimental stage of this research.

  5. Sensitivity of continental United States atmospheric budgets of oxidized and reduced nitrogen to dry deposition parametrizations

    PubMed Central

    Dennis, Robin L.; Schwede, Donna B.; Bash, Jesse O.; Pleim, Jon E.; Walker, John T.; Foley, Kristen M.

    2013-01-01

    Reactive nitrogen (Nr) is removed by surface fluxes (air–surface exchange) and wet deposition. The chemistry and physics of the atmosphere result in a complicated system in which competing chemical sources and sinks exist and impact that removal. Therefore, uncertainties are best examined with complete regional chemical transport models that simulate these feedbacks. We analysed several uncertainties in regional air quality model resistance analogue representations of air–surface exchange for unidirectional and bi-directional fluxes and their effect on the continental Nr budget. Model sensitivity tests of key parameters in dry deposition formulations showed that uncertainty estimates of continental total nitrogen deposition are surprisingly small, 5 per cent or less, owing to feedbacks in the chemistry and rebalancing among removal pathways. The largest uncertainties (5%) occur with the change from a unidirectional to a bi-directional NH3 formulation followed by uncertainties in bi-directional compensation points (1–4%) and unidirectional aerodynamic resistance (2%). Uncertainties have a greater effect at the local scale. Between unidirectional and bi-directional formulations, single grid cell changes can be up to 50 per cent, whereas 84 per cent of the cells have changes less than 30 per cent. For uncertainties within either formulation, single grid cell change can be up to 20 per cent, but for 90 per cent of the cells changes are less than 10 per cent. PMID:23713122

  6. Climate, not atmospheric deposition, drives the biogeochemical mass-balance of a mountain watershed

    USGS Publications Warehouse

    Baron, Jill S.; Heath, Jared

    2014-01-01

    Watershed mass-balance methods are valuable tools for demonstrating impacts to water quality from atmospheric deposition and chemical weathering. Owen Bricker, a pioneer of the mass-balance method, began applying mass-balance modeling to small watersheds in the late 1960s and dedicated his career to expanding the literature and knowledge of complex watershed processes. We evaluated long-term trends in surface-water chemistry in the Loch Vale watershed, a 660-ha. alpine/subalpine catchment located in Rocky Mountain National Park, CO, USA. Many changes in surface-water chemistry correlated with multiple drivers, including summer or monthly temperature, snow water equivalent, and the runoff-to-precipitation ratio. Atmospheric deposition was not a significant causal agent for surface-water chemistry trends. We observed statistically significant increases in both concentrations and fluxes of weathering products including cations, SiO2, SO4 2−, and ANC, and in inorganic N, with inorganic N being primarily of atmospheric origin. These changes are evident in the individual months June, July, and August, and also in the combined June, July, and August summer season. Increasingly warm summer temperatures are melting what was once permanent ice and this may release elements entrained in the ice, stimulate chemical weathering with enhanced moisture availability, and stimulate microbial nitrification. Weathering rates may also be enhanced by sustained water availability in high snowpack years. Rapid change in the flux of weathering products and inorganic N is the direct and indirect result of a changing climate from warming temperatures and thawing cryosphere.

  7. Chemical vapour deposition enhanced by atmospheric microwave plasmas: a large-scale industrial process or the next nanomanufacturing tool?

    NASA Astrophysics Data System (ADS)

    Belmonte, T.; Gries, T.; Cardoso, R. P.; Arnoult, G.; Kosior, F.; Henrion, G.

    2011-04-01

    This paper describes several specific aspects of atmospheric plasma deposition carried out with a microwave resonant cavity. Deposition over a wide substrate is first studied. We show that high deposition rates (several hundreds of μm h-1) are due to localization of fluxes on the substrate by convection when slightly turbulent flows are used. Next, we describe possible routes to localize deposition over a nanometre-sized area. Scaling down atmospheric plasma deposition is possible and two strategies to reach nanometre scales are described. Finally, we study self-organization of SiO2 nanodots deposited by chemical vapour deposition at atmospheric pressure enhanced by an Ar-O2 micro-afterglow operating at high temperature (>1200 K). When the film being deposited is thin enough (~500 nm) nanodots are obtained and they can be assembled into threads to create patterned surfaces. When the coating becomes thicker (~1 µm), and for relatively high content in HMDSO, SiO2 walls forming hexagonal cells are obtained.

  8. Sulfur isotope dynamics in two central european watersheds affected by high atmospheric deposition of SO x

    NASA Astrophysics Data System (ADS)

    Novák, Martin; Kirchner, James W.; Groscheová, Hana; Havel, Miroslav; Černý, Jiří; Krejčí, Radovan; Buzek, František

    2000-02-01

    Sulfur fluxes and δ34S values were determined in two acidified small watersheds located near the Czech-German border, Central Europe. Sulfur of sulfate aerosol in the broader region (mean δ 34S of 7.5‰ CDT) was isotopically heavier than sulfur of airborne SO 2 (mean δ 34S of 4.7‰). The annual atmospheric S deposition to the Jezeřı´ watershed decreased markedly in 1993, 1994, and 1995 (40, 33, and 29 kg/ ha · yr), reflecting reductions in industrial S emissions. Sulfur export from Jezeří via surface discharge was twice atmospheric inputs, and increased from 52 to 58 to 85 kg/ha · yr over the same three-year period. The δ 34S value of Jezeřı´ streamflow was 4.5 ± 0.3‰, intermediate between the average atmospheric deposition (5.4 ± 0.2‰) and soil S (4.0 ± 0.5‰), suggesting that the excess sulfate in runoff comes from release of S from the soil. Bedrock is not a plausible source of the excess S, because its S concentration is very low (<0.003 wt.%) and because its δ 34S value is too high (5.8‰) to be consistent with the δ 34S of runoff. A sulfur isotope mixing model indicated that release of soil S accounted for 64 ± 33% of sulfate S in Jezeřı´ discharge. Approximately 30% of total sulfate S in the discharge were organically cycled. At Načetı´n, the same sequence of δ34S IN > δ34S OUT > δ34S SOIL was observed. The seasonality found in atmospheric input (higher δ 34S in summer, lower δ 34S in winter) was preserved in shallow (<10 cm) soil water, but not in deeper soil water. δ 34S values of deeper (>10 cm) soil water (4.8 ± 0.2‰) were intermediate between those of atmospheric input (5.9 ± 0.3‰) and Nac̆etín soils (2.4 ± 0.1‰), again suggesting that remobilization of soil S accounts for a significant fraction (roughly 40 ± 10%) of the S in soil water at Načetı´n. The inventories of soil S at both of these sites are legacies of more intense atmospheric pollution during previous decades, and are large enough (740

  9. Dissemination, resuspension, and filtration of carbon fibers. [aircraft fires

    NASA Technical Reports Server (NTRS)

    Elber, W.

    1980-01-01

    Carbon fiber transport was studied using mathematical models established for other pollution problems. It was demonstrated that resuspension is not a major factor contributing to the risk. Filtration and fragmentation tests revealed that fiber fragmentation shifts the fiber spectrum to shorter mean lengths in high velocity air handling systems.

  10. Sediment resuspension, redeposition, and focusing in a small dimictic reservoir

    USGS Publications Warehouse

    James, W.F.; Barko, J.W.

    1993-01-01

    Rates of seston (dry mass) sedimentation, estimated from sediment traps (ST rates) and sediment cores (SC rates), were determined at four water depths to examine seasonal and annual sedimentation patterns in Eau Galle Reservoir, Wisconsin (USA). Annual ST rates overestimated annual SC rates at water depths less-than-or-equal-to 4 m, suggesting that sediment resuspension and redeposition in relatively shallow regions of the reservoir caused the overestimate. In contrast, annual ST and SC rates were similar at depths >4 m, suggesting minimal sediment resuspension and redeposition in deeper regions of the reservoir. Using variations in daily ST rates estimated during the autumn overturn of 1987, we developed a conceptual framework for estimating sediment resuspension, redeposition, and focusing. Resuspension of shallow sediments during this particular period accounted for over 50% of the annual ST rate at depths less-than-or-equal-to 4 m. At the same time, focusing of resuspended shallow sediments to deeper regions accounted for about 20% of the annual ST rate at depths >4 m. Our results indicate that during autumn overturn in this reservoir, peaks in sedimentation in the deep, profundal region, estimated from sediment traps, may reflect sediment focused from shallow regions rather than sediment resuspended from the profundal region.

  11. SEDIMENT SUSPENSION AND RESUSPENSION FROM SMALL-CRAFT INDUCED TURBULENCE

    EPA Science Inventory

    The objective of this study was to determine if small vessels, operating in shallow waters, have any measurable effects in producing increased turbidities by the resuspension of fine sediments which may affect submerged aquatic vegetation (SAV). A two-phase approach was used, con...

  12. A sediment resuspension and water quality model of Lake Okeechobee

    USGS Publications Warehouse

    James, R.T.; Martin, J.; Wool, T.; Wang, P.-F.

    1997-01-01

    The influence of sediment resuspension on the water quality of shallow lakes is well documented. However, a search of the literature reveals no deterministic mass-balance eutrophication models that explicitly include resuspension. We modified the Lake Okeeehobee water quality model - which uses the Water Analysis Simulation Package (WASP) to simulate algal dynamics and phosphorus, nitrogen, and oxygen cycles - to include inorganic suspended solids and algorithms that: (1) define changes in depth with changes in volume; (2) compute sediment resuspension based on bottom shear stress; (3) compute partition coefficients for ammonia and ortho-phosphorus to solids; and (4) relate light attenuation to solids concentrations. The model calibration and validation were successful with the exception of dissolved inorganic nitrogen species which did not correspond well to observed data in the validation phase. This could be attributed to an inaccurate formulation of algal nitrogen preference and/or the absence of nitrogen fixation in the model. The model correctly predicted that the lake is lightlimited from resuspended solids, and algae are primarily nitrogen limited. The model simulation suggested that biological fluxes greatly exceed external loads of dissolved nutrients; and sedimentwater interactions of organic nitrogen and phosphorus far exceed external loads. A sensitivity analysis demonstrated that parameters affecting resuspension, settling, sediment nutrient and solids concentrations, mineralization, algal productivity, and algal stoichiometry are factors requiring further study to improve our understanding of the Lake Okeechobee ecosystem.

  13. Comparison of mercury mass loading in streams to atmospheric deposition in watersheds of Western North America: Evidence for non-atmospheric mercury sources.

    PubMed

    Domagalski, Joseph; Majewski, Michael S; Alpers, Charles N; Eckley, Chris S; Eagles-Smith, Collin A; Schenk, Liam; Wherry, Susan

    2016-10-15

    Annual stream loads of mercury (Hg) and inputs of wet and dry atmospheric Hg deposition to the landscape were investigated in watersheds of the Western United States and the Canadian-Alaskan Arctic. Mercury concentration and discharge data from flow gauging stations were used to compute annual mass loads with regression models. Measured wet and modeled dry deposition were compared to annual stream loads to compute ratios of Hg stream load to total Hg atmospheric deposition. Watershed land uses or cover included mining, undeveloped, urbanized, and mixed. Of 27 watersheds that were investigated, 15 had some degree of mining, either of Hg or precious metals (gold or silver), where Hg was used in the amalgamation process. Stream loads in excess of annual Hg atmospheric deposition (ratio>1) were observed in watersheds containing Hg mines and in relatively small and medium-sized watersheds with gold or silver mines, however, larger watersheds containing gold or silver mines, some of which also contain large dams that trap sediment, were sometimes associated with lower load ratios (<0.2). In the non-Arctic regions, watersheds with natural vegetation tended to have low ratios of stream load to Hg deposition (<0.1), whereas urbanized areas had higher ratios (0.34-1.0) because of impervious surfaces. This indicated that, in ecosystems with natural vegetation, Hg is retained in the soil and may be transported subsequently to streams as a result of erosion or in association with dissolved organic carbon. Arctic watersheds (Mackenzie and Yukon Rivers) had a relatively elevated ratio of stream load to atmospheric deposition (0.27 and 0.74), possibly because of melting glaciers or permafrost releasing previously stored Hg to the streams. Overall, our research highlights the important role of watershed characteristics in determining whether a landscape is a net source of Hg or a net sink of atmospheric Hg. PMID:27015962

  14. Using In-Situ Deposition of Metallic Thin Films on Mars to Monitor Atmospheric H20

    NASA Technical Reports Server (NTRS)

    Zent, A. P.; Quinn, R. C.; Grunthaner, F. G.; Towner M.; Zanecki, J.; Ringrose, T.

    2005-01-01

    We describe the use of a novel sensor, designed to characterize the reactive nature of the Martian atmosphere, to also characterize the instantaneous abundance of atmospheric H,O. The sensor deposits, in situ, a thin silver film onto a sapphire substrate and monitors oxidation by measuring resistance of the Ag film during both deposition and subsequent oxidation [1,2]. . The evaporation source is placed in the center of a hollow, open-ended tube. On flash heating the source, evaporated metallic silver rapidly reacts with oxidizing gases in the tube, depositing on the tube walls as a resisitive Ag oxide film. Unoxidized silver deposits over the Ag oxides, once the oxidizing gases in the vicinity of the source have been consumed. Since the ends of the tube are open, atmospheric gases in the tube cause a time delay as the evaporated silver initially reacts with the available O2, and H2O; once oxidizing gases in the tube are significantly depleted, a silver film closes the chemiresistor circuit. In principle this operation mode provides a repeatable measure of the variable H2O abundance, since O2, levels are constant in the atmosphere. To explore the utility of the instrument as an H2O sensor, predict its behavior, and identify possible failure modes, we developed a numerical model of the instrument, and exercised it for Mars conditions. The model predicts the behavior of the electrical circuit, the temperature dependence of resistivity for each component, and the resultant Joule heating. The model balances Joule heating against radiation, sensible heat loss to ambient CO2, and, latent heat loss from sublimating Ag. The flux of Ag atoms from the source is tracked continuously. In the gas phase, the number density of Ag, O2, and H2O is calculated, along with their reaction rates on collision. The model suggests that Ag substantially depletes H2O only near the center of the tube. The model supports the hypothesis that the onset of high conductivity between the A u

  15. Riverine Response of Sulfate to Declining Atmospheric Sulfur Deposition in Agricultural Watersheds.

    PubMed

    David, Mark B; Gentry, Lowell E; Mitchell, Corey A

    2016-07-01

    Sulfur received extensive study as an input to terrestrial ecosystems from acidic deposition during the 1980s. With declining S deposition inputs across the eastern United States, there have been many studies evaluating ecosystem response, with the exception of agricultural watersheds. We used long-term (22 and 18 yr) sulfate concentration data from two rivers and recent (6 yr) data from a third river to better understand cycling and transport of S in agricultural, tile-drained watersheds. Sulfate concentrations and yields steadily declined in the Embarras (from ∼10 to 6 mg S L) and Kaskaskia rivers (from 7 to 3.5 mg S L) during the sampling period, with an overall -23.1 and -12.8 kg S ha yr balance for the two watersheds. There was evidence of deep groundwater inputs of sulfate in the Salt Fork watershed, with a much smaller input to the Embarras and none to the Kaskaskia. Tiles in the watersheds had low sulfate concentrations (<10 mg S L), similar to the Kaskaskia River, unless the field had received some form of S fertilizer. A multiple regression model of runoff (cm) and S deposition explained much of the variation in Embarras River sulfate ( = 0.86 and 0.80 for concentrations and yields; = 46). Although atmospheric deposition was much less than outputs (grain harvest + stream export of sulfate), riverine transport of sulfate reflected the decline in inputs. Watershed S balances suggest a small annual depletion of soil organic S pools, and S fertilization will likely be needed at some future date to maintain crop yields. PMID:27380080

  16. Atmospheric Nitrogen Deposition and its Potential Effects on the Mullica River-Great Bay Ecosystem in Southern New Jersey

    NASA Astrophysics Data System (ADS)

    Haag, J. E.; Gao, Y.

    2005-05-01

    To characterize atmospheric inorganic nitrogen deposition to the Mullica River-Great Bay Estuary and to examine its impact on the coastal ecosystem, atmospheric sampling has been conducted at Tuckerton in southern New Jersey since March 2004. A total of 43 precipitation samples have been collected on an event basis using a wet-only automatic precipitation sampler. A total of 23 aerosol samples were also taken during this period of time with a high-volume aerosol sampler. Chemical analysis was performed using a Dionex Ion Chromatograph to determine the concentrations of nitrate and ammonium in precipitation and associated with aerosols. Atmospheric deposition of nitrate and ammonium were calculated using simple wet and dry atmospheric deposition models. The results show that nitrate and ammonium concentrations vary strongly with season, and the highest concentrations were observed during the spring. The average concentrations in precipitation for nitrate and ammonium in the samples collected to date are 2.41 mg l-1 and 0.56 mg l-1, respectively. The average aerosol concentrations are 3.7 μg m-3 for nitrate and 1.5 μg m-3 for ammonium. The results also indicate that wet deposition is the main contributor to the atmospheric nitrogen entering the Mullica River-Great Bay Estuary. High wet deposition rates of nitrogen were seen in the spring and summer with total average values of 429.08 mg m-2 month-1 for the spring and 229.28 mg m-2 month-1 for the summer. These results will be combined with satellite ocean color to investigate the effect of atmospheric nitrogen deposition on coastal primary productivity in this ecosystem. The atmospheric nitrogen data can also be combined with water column nutrient data that is being collected at the Jacques Cousteau National Estuarine Research Reserve, to assist in generating a nutrient budget to better manage the coastal resources of the Mullica River-Great Bay Estuary.

  17. Atmospheric deposition of mercury in Atlantic Forest and ecological risk to soil fauna

    NASA Astrophysics Data System (ADS)

    Cristhy Buch, Andressa; Cabral Teixeira, Daniel; Fernandes Correia, Maria Elizabeth; Vieira Silva-Filho, Emmanoel

    2014-05-01

    The increasing levels of mercury (Hg) found in the atmosphere nowadays has a great contribution from anthropogenic sources and has been a great concern in the past two decades in industrialized countries. Brazil is the seventh country with the highest rate of mercury in the atmosphere. Certainly, the petroleum refineries have significant contribution, seen that 100 million m3 of crude oil are annually processed. These refineries contribute with low generation of solid waste; however, a large fraction of Hg can be emitted to the atmosphere. There are sixteen refineries in Brazil, three of them located in the state of Rio de Janeiro. The Hg is a toxic and hazardous trace element, naturally found in the earth crust. The major input of Hg to ecosystems is through atmospheric deposition (wet and dry), being transported in the atmosphere over large distances. The forest biomes are of great importance in the atmosphere/soil cycling of elemental Hg through foliar uptake and subsequent transfer to the soil through litterfall, which play an important role as Hg sink. The Atlantic Forest of Brazil is the greater contributor of fauna and flora biodiversity in the world and, according to recent studies, this biome has the highest concentrations of mercury in litter in the world, as well as in China, at Subtropical Forest. Ecotoxicological assessments can predict the potential ecological risk of Hg toxicity in the soil can lead to impact the soil fauna and indirectly other trophic levels of the food chain within one or more ecosystems. This study aims to determine mercury levels that represent risks to diversity and functioning of soil fauna in tropical forest soils. The study is conducted in two forest areas inserted into conservation units of Rio de Janeiro state. One area is located next to an important petroleum refinery in activity since fifty-two years ago, whereas the other one is located next to other refinery under construction (beginning activities in 2015), which will

  18. Relevance of canopy drip for the accumulation of nitrogen in moss used as biomonitors for atmospheric nitrogen deposition in Europe.

    PubMed

    Meyer, Michaela; Schröder, Winfried; Nickel, Stefan; Leblond, Sébastien; Lindroos, Antti-Jussi; Mohr, Karsten; Poikolainen, Jarmo; Santamaria, Jesus Miguel; Skudnik, Mitja; Thöni, Lotti; Beudert, Burkhard; Dieffenbach-Fries, Helga; Schulte-Bisping, Hubert; Zechmeister, Harald G

    2015-12-15

    High atmospheric deposition of nitrogen (N) impacts functions and structures of N limited ecosystems. Due to filtering and related canopy drip effects forests are particularly exposed to N deposition. Up to now, this was proved by many studies using technical deposition samplers but there are only some few studies analysing the canopy drip effect on the accumulation of N in moss and related small scale atmospheric deposition patterns. Therefore, we investigated N deposition and related accumulation of N in forests and in (neighbouring) open fields by use of moss sampled across seven European countries. Sampling and chemical analyses were conducted according to the experimental protocol of the European Moss Survey. The ratios between the measured N content in moss sampled inside and outside of forests were computed and used to calculate estimates for non-sampled sites. Potentially influencing environmental factors were integrated in order to detect their relationships to the N content in moss. The overall average N content measured in moss was 20.0mgg(-1) inside and 11.9mgg(-1) outside of forests with highest N values in Germany inside of forests. Explaining more than 70% of the variance, the multivariate analyses confirme