Long-term Atmospheric Mercury Wet Deposition at Underhill, Vermont

Keeler, Gerald J.; Gratz, Lynne E.; Al-Wali, Khalid I.

doi:10.1007/s10646-004-6260-3

Cited by 81 publications

(50 citation statements)

References 29 publications

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“…Compared to other seasons, the combination of higher relative concentrations and more precipitation in summer enhanced the overall flux. Similar seasonal patterns were observed in both deposition flux and concentration in remote areas of China (Fu et al, 2010a, b) and North America (Choi et al, 2008;Mason et al, 2000;Keeler et al, 2005;Sanei et al, 2010;Lombard et al, 2011), with the annual maximum in summer. It was suggested by Keeler et al (2005) and Mason et al (2000) that this annual maximum was mainly due to more effective scavenging by rain in summer than by snow in the cold season.…”

Section: Concentration Of Mercury In Precipitation and Wet Depositionsupporting

confidence: 73%

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

et al. 2014

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Abstract.A comprehensive measurement study of mercury wet deposition and size-fractionated particulate mercury (Hg P ) 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 Hg P concentration was 1.10 ± 0.57 ng m −3 . A distinct seasonal distribution of Hg P concentrations was found to be higher in winter as a result of an increase in the PM 10 concentration. Overall, more than half of the Hg P existed in the particle size range less than 2.1 µm. The highest concentration of Hg P in coarse particles was observed in summer, while Hg P 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 Hg P 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 Hg P in fine particles, Hg P in coarse particles contributed more to the total dry deposition due to higher deposition velocities. Negative correlation between precipitation and the Hg P concentration reflected the effect of scavenging of Hg P by precipitation.

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Section: Concentration Of Mercury In Precipitation and Wet Depositionsupporting

confidence: 73%

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

et al. 2014

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“…2b, single precipitation events with elevated Hg deposition levels can account for a substantial portion of the total deposition. Similarly, Keeler et al (2005) also report a single event contributing approximately 17 % to the annual Hg wet deposition load from event-based sampling in Underhill, VT. During the 37-month sampling period at TF, the cumulative Hg wet deposition was 30.78 µg m −2 and the total precipitation depth was 4.28 m. The seasonal and annual variations in Hg concentration and wet deposition are summarized in Table 1. In this study, seasons are delineated according to the calendar definition.…”

Section: Hg Wet Deposition Seasonal Patterns and Inter-annual Variabimentioning

confidence: 85%

“…In North America seasonal patterns in wet deposition are observed in both depositional flux and concentration with the highest values in the summer and lowest values in the winter (Sorensen et al, 1994;Mason et al, 2000;Guentzel et al, 2001;Keeler et al, 2005;VanArsdale et al, 2005;Choi et al, 2008;Prestbo and Gay, 2009). Explanations for this observation include more effective Hg scavenging by rain compared to snow (Sorensen et al, 1994;Mason et al, 2000;Keeler et al, 2005;Selin and Jacob, 2008), a greater availability of soluble Hg due to convective transport in summer events (Guentzel et al, 2001;Keeler et al, 2005), and a summer increase in Hg-containing soil derived particles in the atmosphere (Sorensen et al, 1994).…”

Section: Introductionmentioning

confidence: 99%

Mercury deposition in Southern New Hampshire, 2006–2009

et al. 2011

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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.

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“…GEM is the predominant form (> 95 %) in atmosphere; it is very stable and well mixed hemispherically with a long lifetime of 0.5-2 years (Selin et al, 2007). In contrast, GOM and PBM will deposit more rapidly downwind of their emission sources via wet or dry deposition since GOM and PBM have significantly higher reactivity, deposition velocities, and water solubility (Lin and Pehkonen, 1999;Lindberg et al, 2002;Keeler et al, 2005). Accordingly, mercury is a multi-scale pollutant able to be transported at local-, regional-and larger-scale distances from its sources, and mercury emission speciation has a great impact on the processes and spatial distribution of mercury in the atmosphere (Bieser et al, 2014;Quan et al, 2009;Pai et al, 1999).…”

Section: J Zhu Et Al: Source Attribution and Process Analysis For Amentioning

confidence: 99%

Source attribution and process analysis for atmospheric mercury in eastern China simulated by CMAQ-Hg

et al. 2015

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Abstract.The contribution from different emission sources and atmospheric processes to gaseous elemental mercury (GEM), gaseous oxidized mercury (GOM), particulate bound mercury (PBM) and mercury deposition in eastern China were quantified using the Community Multi-scale Air Quality (CMAQ-Hg) modeling system run with a nested domain. Natural sources (NAT) and six categories of anthropogenic mercury sources (ANTH) including cement production (CEM), domestic life (DOM), industrial boilers (IND), metal production (MET), coal-fired power plants (PP) and traffic (TRA) were considered for source apportionment. NAT were responsible for 36.6 % of annual averaged GEM concentration, which was regarded as the most important source for GEM in spite of obvious seasonal variation. Among ANTH, the influence of MET and PP on GEM were most evident especially in winter. ANTH dominated the variations of GOM and PBM concentrations with contributions of 86.7 and 79.1 %, respectively. Among ANTH, IND were the largest contributor for GOM (57.5 %) and PBM (34.4 %) so that most mercury deposition came from IND. The effect of mercury emitted from out of China was indicated by a > 30 % contribution to GEM concentration and wet deposition. The contributions from nine processes -consisting of emissions (EMIS), gas-phase chemical production/loss (CHEM), horizontal advection (HADV), vertical advection (ZADV), horizontal advection (HDIF), vertical diffusion (VDIF), dry deposition (DDEP), cloud processes (CLDS) and aerosol processes (AERO) -were calculated for process analysis with their comparison in urban and non-urban regions of the Yangtze River delta (YRD). EMIS and VDIF affected surface GEM and PBM concentrations most and tended to compensate each other all the time in both urban and non-urban areas. However, DDEP was the most important removal process for GOM with 7.3 and 2.9 ng m −3 reduced in the surface of urban and non-urban areas, respectively, in 1 day. The diurnal profile variation of processes revealed the transportation of GOM from urban area to non-urban areas and the importance of CHEM/AERO in higher altitudes which partly caused diffusion of GOM downwards to non-urban areas. Most of the anthropogenic mercury was transported and diffused away from urban areas by HADV and VDIF and increased mercury concentrations in non-urban areas by HADV. Natural emissions only influenced CHEM and AERO more significantly than anthropogenic. Local emissions in the YRD contributed 8.5 % more to GEM and ∼ 30 % more to GOM and PBM in urban areas compared to non-urban areas.

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Long-term Atmospheric Mercury Wet Deposition at Underhill, Vermont

Cited by 81 publications

References 29 publications

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

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

Mercury deposition in Southern New Hampshire, 2006–2009

Source attribution and process analysis for atmospheric mercury in eastern China simulated by CMAQ-Hg

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