scholarly journals Direct Measurement of Mercury Deposition at Rural and Suburban Sites in Washington State, USA

Atmosphere ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 35
Author(s):  
Marc W. Beutel ◽  
Lanka DeSilva ◽  
Louis Amegbletor
Keyword(s):  
Direct Measurement ◽  
Dry Deposition ◽  
Low Cost ◽  
Deposition Velocity ◽  
Washington State ◽  
Rural Site ◽  
Storm Events ◽  
Mercury Deposition ◽  
Spatial And Temporal Patterns ◽  
Atmospheric Concentration

Because of mercury’s (Hg) capacity for long-range transport in the atmosphere, and its tendency to bioaccumulate in aquatic biota, there is a critical need to measure spatial and temporal patterns of Hg atmospheric deposition. Dry deposition of Hg is commonly calculated as the product of a measured atmospheric concentration and an assumed deposition velocity. An alternative is to directly assess Hg deposition via accumulation on surrogate surfaces. Using a direct measurement approach, this study quantified Hg deposition at a rural site (Pullman) and suburban site (Puyallup) in Washington State using simple, low-cost equipment. Dry deposition was measured using an aerodynamic “wet sampler” consisting of a Teflon plate, 35 cm in diameter, holding a thin layer (2.5 mm) of recirculating acidic aqueous receiving solution. In addition, wet Hg deposition was measured using a borosilicate glass funnel with a 20-cm-diameter opening and a 1 L Teflon sampling bottle. Hg deposition was estimated based on changes in total Hg in the aqueous phase of the samplers. Dry Hg deposition was 2.4 ± 1.4 ng/m2·h (average plus/minus standard deviation; n = 4) in Pullman and 1.3 ± 0.3 ng/m2·h (n = 6) in Puyallup. Wet Hg deposition was 7.0 ± 4.8 ng/m2·h (n = 4) in Pullman and 1.1 ± 0.2 ng/m2·h (n = 3) in Puyallup. Relatively high rates of Hg deposition in Pullman were attributed to regional agricultural activities that enhance mercury re-emission and deposition including agricultural harvesting and field burning. Hg concentration in precipitation negatively correlated with precipitation depth, indicating that Hg was scavenged from the atmosphere during the beginning of storm events. Because of their relative simplicity and robustness, direct measurement approaches such as those described in this study are useful in assessing Hg deposition, and for comparing results to less direct estimates and model estimates of Hg deposition.

scholarly journals Nitric Acid–Sea Salt Reactions: Implications for Nitrogen Deposition to Water Surfaces

2000 ◽  
Vol 39 (5) ◽  
pp. 725-731 ◽  
Author(s):  
S. C. Pryor ◽  
L. L. Sørensen
Keyword(s):  
Nitric Acid ◽  
Dry Deposition ◽  
Deposition Velocity ◽  
Sea Salt ◽  
Neutral Stability ◽  
Particle Phase ◽  
Spatial And Temporal Patterns ◽  
Wind Speeds ◽  
Horizontal Transport ◽  
Marine Surface Layer

Abstract Many previous studies have indicated the importance of nitric acid (HNO3) reactions on sea salt particles for flux divergence of HNO3 in the marine surface layer. The potential importance of this reaction in determining the spatial and temporal patterns of nitrogen dry deposition to marine ecosystems is investigated using models of sea spray generation and particle- and gas-phase dry deposition. Under horizontally homogeneous conditions with near-neutral stability and for wind speeds between 3.5 and 10 m s−1, transfer of HNO3 to the particle phase to form sodium nitrate may decrease the deposition velocity of nitrogen by over 50%, leading to greater horizontal transport prior to deposition to the sea surface. Conversely, for wind speeds above 10 m s−1, transfer of nitrogen to the particle phase would increase the deposition rate and hence decrease horizontal transport prior to surface removal.

scholarly journals Mercury deposition in Southern New Hampshire, 2006–2009

2011 ◽  
Vol 11 (15) ◽  
pp. 7657-7668 ◽  
Author(s):  
M. A. S. Lombard ◽  
J. G. Bryce ◽  
H. Mao ◽  
R. Talbot
Keyword(s):  
New Hampshire ◽  
Dry Deposition ◽  
Wet Deposition ◽  
Winter Precipitation ◽  
Rural Site ◽  
Mercury Deposition ◽  
Mixing Ratios ◽  
Order Of Magnitude ◽  
Aqueous Mercury ◽  
Event Based

Abstract. The atmospheric deposition of mercury (Hg) occurs via several mechanisms including wet, dry, and occult processes. In an effort to understand the atmospheric cycling and seasonal depositional characteristics of Hg, event-based wet deposition samples and reactive gaseous Hg (RGM) measurements were collected for approximately 3 years at Thompson Farm (TF), a near-coastal rural site in Durham, NH, part of the University of New Hampshire AIRMAP Observing Network. Total aqueous mercury exhibited seasonal patterns in Hg wet deposition at TF. The lowest Hg wet deposition was measured in the winter with an average total seasonal deposition of 1.56 μg m−2 compared to the summer average of 4.71 μg m−2. Inter-annual differences in total wet deposition are generally linked with precipitation volume, with the greatest deposition occurring in the wettest year. Relationships between surface level RGM and Hg wet deposition were also investigated based on continuous RGM measurements at TF from November 2006 to September 2009. No correlations were observed between RGM mixing ratios and Hg wet deposition, however the ineffective scavenging of RGM during winter precipitation events was evidenced by the less frequent depletion of RGM below the detection level. Seasonal dry deposition of reactive gaseous Hg (RGM) was estimated using an order-of-magnitude approach. RGM mixing ratios and dry deposition estimates were greatest during the winter and spring. The seasonal ratios of Hg wet deposition to RGM dry deposition vary by up to a factor of 80.

scholarly journals Mercury deposition in southern New Hampshire, 2006–2009

2011 ◽  
Vol 11 (2) ◽  
pp. 4569-4598
Author(s):  
M. A. S. Lombard ◽  
J. G. Bryce ◽  
H. Mao ◽  
R. Talbot
Keyword(s):  
New Hampshire ◽  
Dry Deposition ◽  
Wet Deposition ◽  
Meteorological Data ◽  
Primary Source ◽  
Rural Site ◽  
Mercury Deposition ◽  
Mixing Ratios ◽  
Order Of Magnitude ◽  
Aqueous Mercury

Abstract. Mercury (Hg) is a global contaminant due to its toxicity and ubiquitous presence in the atmosphere. The primary source of Hg to terrestrial and aquatic ecosystems is atmospheric deposition. In an effort to understand the atmospheric cycling and depositional characteristics of Hg, event-based wet deposition samples were collected from July 2006 to September 2009 at Thompson Farm (TF), a near-coastal rural site in Durham, NH, part of the University of New Hampshire AIRMAP Observing Network. Total aqueous mercury exhibited seasonal trends in Hg wet deposition at TF. The lowest Hg wet deposition occurred in the winter with an average total seasonal deposition of 1.56 μg m−2 compared to the summer average of 4.71 μg m−2. Inter-annual differences are generally linked with precipitation volume, with the greatest deposition occurring in the wettest year. Comparisons of Hg wet deposition trends with meteorological data and ambient gas phase mixing ratios revealed weak correlations. The strongest correlation was observed between maximum hourly precipitation rate and Hg wet deposition, and the relationship was strongly driven by extreme events. Dry deposition of reactive gaseous Hg (RGM) was estimated based on continuous RGM measurements at TF from October 2006 to September 2009 using an order-of-magnitude approach. Comparisons between Hg wet deposition and RGM dry deposition suggest that the seasonal ratios of Hg wet deposition to RGM dry deposition vary by up to a factor of 80. Additional studies of seasonal differences in Hg deposition mechanisms (wet vs. dry) may provide a better understanding of the biogeochemical cycling of Hg.

scholarly journals Evaluating Simple Methodology for Piezoelectric Level Sensors Protection

Proceedings ◽  
2019 ◽  
Vol 48 (1) ◽  
pp. 30
Author(s):  
Luis Hamilton Pospissil Garbossa ◽  
Argeu Vanz ◽  
Matias Guilherme Boll ◽  
Hamilton Justino Vieira
Keyword(s):  
Water Level ◽  
Flood Control ◽  
Low Cost ◽  
Solid Particles ◽  
Storm Events ◽  
Sewer Systems ◽  
Continuous Monitor ◽  
Level Monitoring ◽  
Water Level Monitoring

The increasing frequency of extreme storm events has implications for the operation of sewer systems, storm water, flood control monitoring and tide level variations. Accurate and continuous monitor water level monitoring is demanded in different environments. Piezoelectric sensors are widely used for water level monitoring and work submerged in waters subject to the presence of solid particles, biological fouling and saltwater oxidation. This work aimed to develop a simple, low-cost methodology to protect sensors over long-term deployment. The results show that simple actions, costing less than 2 EUR, can protect and extend the lifecycle of equipment worth over 2000 EUR, ensuring continuous monitoring and maintaining quality measurements.

Linear regression analyses with censored data: estimation of PAH washout ratios and dry deposition velocities to a snow surface

1995 ◽  
Vol 22 (4) ◽  
pp. 819-833 ◽  
Author(s):  
Mukesh Sharma ◽  
Neil R. Thomson ◽  
Edward A. McBean
Keyword(s):  
Least Squares ◽  
Censored Data ◽  
Dry Deposition ◽  
Least Squares Method ◽  
Deposition Velocity ◽  
Snow Surface ◽  
Regression Analyses ◽  
Doubly Censored Data ◽  
Doubly Censored ◽  
Censored Observations

Detection limits of analyzing instruments are the main reason for censored observations of pollutant concentrations. An iterative least squares method for regression analyses is developed to suit the doubly censored data commonly observed in environmental engineering. The modified iterative least squares method utilizes the expected values of censored observations estimated from the probability density function of doubly censored data in a regression process. The modified method is examined for bias in the estimation of the parameters of a linear model, and in the estimation of the standard deviation of the regression. A mechanistic model for atmospheric transport and deposition of polycyclic aromatic hydrocarbons (PAHs) to a snow surface is formulated by utilizing the long-term PAH retention property of deep snowpacks. The modified iterative least squares method is applied to estimate the deposition parameters (dry deposition velocity and washout ratio) for various PAH species, since some of the PAH deposition levels were below the minimum detection limit of the analyzing instrument. The estimated parameters are examined statistically, and compare favourably with previously reported estimates of these parameters. Key words: censored data, regression, iterative least squares, PAHs, dry deposition velocity, washout ratio.

scholarly journals Triple oxygen isotopes indicate urbanization affects sources of nitrate in wet and dry atmospheric deposition

2018 ◽  
Author(s):  
David M. Nelson ◽  
Urumu Tsunogai ◽  
Ding Dong ◽  
Takuya Ohyama ◽  
Daisuke D. Komatsu ◽  
...  
Keyword(s):  
Dry Deposition ◽  
Wet Deposition ◽  
Urban Environments ◽  
Rural Site ◽  
Urban Site ◽  
Peroxy Radicals ◽  
Long Distance ◽  
Wet And Dry Deposition ◽  
Atmospheric Nitrate ◽  
Nitrate Deposition

Abstract. Atmospheric nitrate deposition resulting from anthropogenic activities negatively affects human and environmental health. Identifying deposited nitrate that is produced locally vs. that originating from long-distance transport would help inform efforts to mitigate such impacts. However, distinguishing the relative transport distances of atmospheric nitrate in urban areas remains a major challenge since it may be produced locally and/or come from upwind regions. To address this uncertainty we assessed spatiotemporal variation in monthly weighted-average Δ17O and δ15N values of wet and dry nitrate deposition during one year at urban and rural sites along the western coast of the northern Japanese island of Hokkaido, downwind of the East Asian continent. Δ17O values of nitrate in wet deposition at the urban site mirrored those of wet and dry deposition at the rural site, ranging between ~ +22 and +30 ‰ with higher values during winter and lower values in summer, which suggests greater relative importance of oxidation of NO2 by O3 during winter and OH during summer. In contrast, Δ17O values of nitrate in dry deposition at the urban site were lower (+19–+25 ‰) and displayed less distinct seasonal variation. Furthermore, the difference between δ15N values of nitrate in wet and dry nitrate deposition was, on average, 3 ‰ greater at the urban than rural site, and Δ17O and δ15N values were correlated for both forms of deposition at both sites with the exception of dry deposition at the urban site. These results suggest that, relative to nitrate in wet deposition in urban environments and wet and dry deposition in rural environments, nitrate in dry deposition in urban environments forms from relatively greater oxidation of NO by peroxy radicals and/or oxidation of NO2 by OH. Given greater concentrations of peroxy radicals and OH in cities, these results imply that dry nitrate deposition results from local NOx emissions more so than wet deposition, which is transported longer distances. These results illustrate the value of stable isotope data for distinguishing the transport distances and reaction pathways of atmospheric nitrate pollution.

scholarly journals Revising global ozone dry deposition estimates based on a new mechanistic parameterisation for air-sea exchange and the multi-year MACC composition reanalysis

2017 ◽  
Author(s):  
Ashok K. Luhar ◽  
Matthew T. Woodhouse ◽  
Ian E. Galbally
Keyword(s):  
Chemical Reaction ◽  
Dry Deposition ◽  
Tropospheric Ozone ◽  
Surface Resistance ◽  
Chemical Reactivity ◽  
Deposition Velocity ◽  
Water Layer ◽  
Turbulent Transfer ◽  
Dominant Term ◽  
Deposition Velocities

Abstract. Dry deposition at the Earth’s surface is an important sink of atmospheric ozone. Currently, dry deposition of ozone to the ocean surface in atmospheric chemistry models has the largest uncertainty compared to deposition to other surface types, with implications for global tropospheric ozone budget and associated radiative forcing. Most models assume that the dominant term of surface resistance in the parameterisation of ozone dry deposition velocity at the oceanic surface is constant. We present a consistent, process-based parameterisation scheme for air-sea exchange in which the surface resistance accounts for the simultaneous waterside processes of ozone solubility, molecular diffusion, turbulent transfer, and a first-order chemical reaction of ozone with dissolved iodide. The new scheme makes the following realistic assumptions: (a) the thickness of the top water layer is of the order of a reaction-diffusion length scale (a few micrometres) within which ozone loss is dominated by chemical reaction and the influence of waterside turbulent transfer is negligible; (b) in the water layer below, both chemical reaction and waterside turbulent transfer act together and are accounted for; and (c) iodide (hence chemical reactivity) is present through the depth of the oceanic mixing layer. The asymptotic behaviour of the new scheme is consistent with the known limits when either chemical reaction or turbulent transfer dominates. It has been incorporated into the ACCESS-UKCA global chemistry-climate model and the results are evaluated against dry deposition velocities from currently best available open-ocean measurements. In order to better quantify the global dry deposition loss and its interannual variability, the modelled 3-h ozone deposition velocities are combined with the 3-h MACC (Monitoring Atmospheric Composition and Climate) reanalysis ozone for the years 2003–2012. The resulting ozone dry deposition is found to be 98.4 ± 4.5 Tg O3 yr−1 for the ocean and 722.8 ± 20.9 O3 yr−1 globally. The new estimate of the ocean component is approximately a third of the current model estimates. This reduction corresponds to an approximately 20 % decrease in the total global ozone dry deposition, which is equivalent to an increase of approximately 5 % in the modelled tropospheric ozone burden and a similar increase in tropospheric ozone lifetime.

scholarly journals Characteristics of atmospheric mercury deposition and size-fractionated particulate mercury in urban Nanjing, China

2014 ◽  
Vol 14 (5) ◽  
pp. 2233-2244 ◽  
Author(s):  
J. Zhu ◽  
T. Wang ◽  
R. Talbot ◽  
H. Mao ◽  
X. Yang ◽  
...  
Keyword(s):  
Dry Deposition ◽  
Wet Deposition ◽  
Fine Particles ◽  
Unit Area ◽  
Atmospheric Mercury ◽  
Anthropogenic Sources ◽  
Deposition Flux ◽  
Coarse Particles ◽  
Mercury Deposition ◽  
Particulate Mercury

Abstract. A comprehensive measurement study of mercury wet deposition and size-fractionated particulate mercury (HgP) concurrent with meteorological variables was conducted from June 2011 to February 2012 to evaluate the characteristics of mercury deposition and particulate mercury in urban Nanjing, China. The volume-weighted mean (VWM) concentration of mercury in rainwater was 52.9 ng L−1 with a range of 46.3–63.6 ng L−1. The wet deposition per unit area was averaged 56.5 μg m−2 over 9 months, which was lower than that in most Chinese cities, but much higher than annual deposition in urban North America and Japan. The wet deposition flux exhibited obvious seasonal variation strongly linked with the amount of precipitation. Wet deposition in summer contributed more than 80% to the total amount. A part of contribution to wet deposition of mercury from anthropogenic sources was evidenced by the association between wet deposition and sulfates, as well as nitrates in rainwater. The ions correlated most significantly with mercury were formate, calcium, and potassium, which suggested that natural sources including vegetation and resuspended soil should be considered as an important factor to affect the wet deposition of mercury in Nanjing. The average HgP concentration was 1.10 ± 0.57 ng m−3. A distinct seasonal distribution of HgP concentrations was found to be higher in winter as a result of an increase in the PM10 concentration. Overall, more than half of the HgP existed in the particle size range less than 2.1 μm. The highest concentration of HgP in coarse particles was observed in summer, while HgP in fine particles dominated in fall and winter. The size distribution of averaged mercury content in particulates was bimodal, with two peaks in the bins of < 0.7 μm and 4.7–5.8 μm. Dry deposition per unit area of HgP was estimated to be 47.2 μg m−2 using meteorological conditions and a size-resolved particle dry deposition model. This was 16.5% less than mercury wet deposition. Compared to HgP in fine particles, HgP in coarse particles contributed more to the total dry deposition due to higher deposition velocities. Negative correlation between precipitation and the HgP concentration reflected the effect of scavenging of HgP by precipitation.

scholarly journals Preliminary estimation of black carbon deposition from Nepal Climate Observatory-Pyramid data and its possible impact on snow albedo changes over Himalayan glaciers during the pre-monsoon season

2010 ◽  
Vol 10 (4) ◽  
pp. 9291-9328 ◽  
Author(s):  
T. J. Yasunari ◽  
P. Bonasoni ◽  
P. Laj ◽  
K. Fujita ◽  
E. Vuillermoz ◽  
...  
Keyword(s):  
Lower Bound ◽  
Size Distribution ◽  
Black Carbon ◽  
Dry Deposition ◽  
Monsoon Season ◽  
Deposition Velocity ◽  
Himalayan Region ◽  
Snow Surface ◽  
Concentration Data ◽  
Snow Albedo

Abstract. The possible minimal range of reduction in snow surface albedo due to dry deposition of black carbon (BC) in the pre-monsoon period (March–May) was estimated as a lower bound together with the estimation of its accuracy, based on atmospheric observations at the Nepal Climate Observatory-Pyramid (NCO-P) sited at 5079 m a.s.l. in the Himalayan region. We estimated a total BC deposition rate of 2.89 μg m−2 day−1 providing a total deposition of 266 μg m−2 for March–May at the site, based on a calculation with a minimal deposition velocity of 1.0×10−4 m s−1 with atmospheric data of equivalent BC concentration. Main BC size at NCO-P site was determined as 103.1–669.8 nm by correlation analysis between equivalent BC concentration and particulate size distribution in the atmosphere. We also estimated BC deposition from the size distribution data and found that 8.7% of the estimated dry deposition corresponds to the estimated BC deposition from equivalent BC concentration data. If all the BC is deposited uniformly on the top 2-cm pure snow, the corresponding BC concentration is 26.0–68.2 μg kg−1 assuming snow density variations of 195–512 kg m−3 of Yala Glacier close to NCO-P site. Such a concentration of BC in snow could result in 2.0–5.2% albedo reductions. From a simple numerical calculations and if assuming these albedo reductions continue throughout the year, this would lead to a runoff increases of 70–204 mm of water drainage equivalent of 11.6–33.9% of the annual discharge of a typical Tibetan glacier. Our estimates of BC concentration in snow surface for pre-monsoon season can be considered comparable to those at similar altitude in the Himalayan region, where glaciers and perpetual snow region starts in the vicinity of NCO-P. Our estimates from only BC are likely to represent a lower bound for snow albedo reductions, since a fixed slower deposition velocity was used and atmospheric wind and turbulence effects, snow aging, dust deposition, and snow albedo feedbacks were not considered. This study represents the first investigation about BC deposition on snow from atmospheric aerosol data in Himalayas and related albedo effect is especially the first track at the southern slope of Himalayas.

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