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Mercury (Hg) emissions from domestic biomass combustion for space heating

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... Recently, the Aethalometer model, which utilizes the light-absorbing signals of aerosol at multi-wavelength, has been developed for source apportionment studies, especially for BB identification (Civerolo et al., 2014;Huang et al., 2011;Martinsson et al., 2017;Sandradewi et al., Peer review under responsibility of Turkish National Committee for Air Pollution Research and Control. 2008;Wang et al., 2010Wang et al., , 2011. ...
... Studies suggested that Delta-C, the difference between ultraviolet black carbon (UVBC, 370 nm) and black carbon at 880 nm (BC), can be used as an indicator of BB (Allen et al., 2004;Wang et al., 2010Wang et al., , 2011. It was further found that the concentrations of and correlations between PBM and Delta-C were enhanced during the BB episodes at three sampling sites in northern New York and during winter wood combustion episodes in Huntington forest and Rochester (Huang et al., 2011;Wang et al., 2010). These results indicated that PBM and UV-sensitive carbonaceous aerosols could be emitted from biomass burning simultaneously. ...
... These results indicated that PBM and UV-sensitive carbonaceous aerosols could be emitted from biomass burning simultaneously. These studies were all conducted at low-elevation sites close to the burning sources (Huang et al., 2011;Wang et al., 2010). However, a recent study by Guo et al. (2021) has also observed good correlations between PBM and carbonaceous species (i.e. ...
Article
Southeast Asia is a major biomass burning (BB) source area and BB has been identified as an important source of mercury (Hg) and aerosols to the atmosphere. Previous studies found correlations between atmospheric Hg and Delta-C (BC370–BC880) during the BB episodes in low-elevation BB source areas; however, whether this relationship persists during long-range transport remains unknown. Lulin Atmospheric Background Station (LABS), a high mountain background site in central Taiwan, has monitored the impact of BB long-range transports from Southeast Asia on atmospheric Hg and aerosols in downwind areas since 2006 and 2008, respectively. As such, these data provide an opportunity to investigate the relationship between atmospheric Hg (PBM and GOM) and aerosol optical properties, such as Delta-C and absorption Ångström exponent (AAE370-880). In this study, three long-range transport BB events were observed at LABS in the springtime during 2014–2016. Significant positive correlations with PBM/GOM were observed for Delta-C and (R2 = 0.34–0.51) and AAE370-880 (R2 = 0.41–0.54) during the BB events, while poor correlations were shown under non-BB episodes. Additionally, the positive correlation between PBM and AAE370-880 suggests that the Hg(II) may be preferably absorbed onto organic aerosols or originated from the same emission sources. This study demonstrated that AAE370-880 can be used to identify the source of Hg(II) from BB long-range transport. In addition, our results also indicated the influences of aerosol chemical compositions on the partitioning of Hg(II), which is important to further the understanding of atmospheric Hg cycling.
... The atmospheric chemistry and sources of mercury vary with location (industrial, urban, rural, inland, marine, and Arctic) . Recent studies have suggested that biomass burning might be an important source of atmospheric mercury; in the winter from anthropogenic wood combustion, especially in the northeastern United States (Choi et al., 2008a(Choi et al., , 2008bHuang et al., 2011;Zhou et al., 2016) and in the summer from wildfires (Wang et al., 2010;Webster et al., 2016). Urban areas are often affected by emissions from local sources (Landis et al., 2004;Seo et al., 2016) such as reemission of legacy Hg (Gratz, 2015) and municipal solid waste landfill emissions (Tao et al., 2017). ...
... The GEM detection limit was 0.1 ng/m 3 as reported by the instrument manufacturer (Tekran, 2011). The detection limits for GOM and PBM were 0.46 and 1.10 pg/m 3 , respectively, calculated as 3 times the standard deviation of the system blank values (Huang et al., 2011). The uncertainty of GOM has been reported by several researchers (Lyman et al., 2010;Jaffe et al., 2014;Gustin et al., 2013) since its concentration can be influenced by the ambient ozone concentration and water vapor (Jaffe et al., 2014). ...
... The average PBM concentration was highest in winter (December, January, February) 2013 (ANOVA on ranks, p b 0.01). Higher GOM and PBM concentrations in spring/summer (June, July, August) and winter, respectively, resulted from faster mercury oxidization processes in summer (Choi et al., 2013) and increased emissions from wood combustion (Huang et al., 2011;Huang et al., 2017), poorer atmospheric dispersion conditions, and increased sorption of semi-volatile compounds including GOM at lower temperatures in winter (ANOVA on ranks, p b 0.01) (Lynam and Keeler, 2005;Zhang et al., 2016). Concentrations of CO (199 ± 85 ppb), SO 2 (1.10 ± 1.72 ppb), NO 2 (7.13 ± 4.95 ppb), NO (3.27 ± 6.64 ppb), O 3 (30.6 ± 13.6 ppb) and PM 2.5 (7.08 ± 4.98 μg/m 3 ) were measured concurrently with Hg. ...
Article
Gaseous elemental mercury (GEM), gaseous oxidized mercury (GOM), and particle-bound mercury (PBM) were measured continuously in Rochester, NY (NY43) from January 2012 to December 2014. Continuous measurements of ozone (O3), sulfur dioxide (SO2), carbon monoxide (CO), nitrogen oxide (NO), nitrogen dioxide (NO2), particulate matter (PM2.5), and meteorological data were also made at this site. A principal component analysis (PCA) of the resulting 15 variables showed that the ambient mercury in Rochester was primarily produced by non-local sources in contrast to earlier studies that showed that local sources were present. Positive matrix factorization (PMF) analysis of the atmospheric mercury and other pollutant species concentrations showed that transport and atmospheric processes have become the major source of mercury in Rochester. Conditional bivariate probability function (CBPF) and potential source contribution function (PSCF) were used to identify local and distant mercury sources. The results in this study showed that the closure of a coal-fired power plant and promulgation of several fuel quality policies reduced local mercury emissions making long-distance transport the major source of mercury in Rochester.
... Potential indoor Hg sources include wood combustion and releases from Hg-containing thermostats, building materials, and consumer products [4,34]. Huang et al. [35] reported that domestic wood combustion may be an important source of oxidized mercury (mostly in the particulate phase) in northern climates in winter. Their measurements determined that Hg is emitted from domestic biomass combustion as gaseous elemental Hg, gaseous oxidized Hg, and fine particle-bound Hg, in proportions that vary depending on combustion conditions, including the type of fuel (e.g., pellets or wood) and combustion temperature [35]. ...
... Huang et al. [35] reported that domestic wood combustion may be an important source of oxidized mercury (mostly in the particulate phase) in northern climates in winter. Their measurements determined that Hg is emitted from domestic biomass combustion as gaseous elemental Hg, gaseous oxidized Hg, and fine particle-bound Hg, in proportions that vary depending on combustion conditions, including the type of fuel (e.g., pellets or wood) and combustion temperature [35]. Of the 1025 participating homes in the present study, 308 (30%) used wood fuel for space heating. ...
... In southern Ontario, for example, the average soil organic carbon content is 2.34% [44], and TC concentrations vary between 1.82 and 3.39% in typical agricultural soil [45]. The sources of organic carbon in house dust are varied and include human and pet hair, skin flakes, fibers, synthetic compounds (e.g., musks, phthalates, flame retardants) and products of combustion, including cooking activities and wood fuel [12,35,46]. Soil is also a source of organic carbon in indoor dust, as soil particles tracked indoors may contribute organic carbon to house dust, particularly when outdoor footwear is not removed [46,47]. ...
Article
Full-text available
Mercury (Hg) is one of the top ten chemicals of concern for public health, according to the World Health Organization. This study investigates Hg concentrations in house dust collected from urban single family homes, to better understand typical indoor residential exposures. Using direct solid sample analysis, total Hg and carbon (TC) were determined in the <80 µm fraction of settled dust samples collected under the Canadian House Dust Study. Hg concentrations displayed a log-normal distribution with median/geomean of 0.68/0.70 mg/kg (n = 995). A small subset (<1%) of homes exhibited anomalously high dust Hg concentrations (>9.0 mg/kg). A comparison of Hg concentrations in fresh dust and household vacuum dust collected from the same homes indicated no significant difference in the two sampling methods. Total carbon concentrations displayed a median/geomean of 29.3/28.5% (n = 1011). A significant correlation between total Hg and TC in house dust (p < 0.00001) reflects the association between Hg and organic carbon previously observed in soil and sediments. The results of this study indicate a 10-fold enrichment in house dust compared with the average background concentrations reported for soil and sediments (0.07 mg/kg). The observed enrichment is attributable to Hg emissions from indoor sources and/or Hg carried home from occupational sources.
... Levoglucosan and potassium have been widely used as the tracer of BB in source apportionment studies (Jordan et al., 2006;Genberg et al., 2011;Huang et al., 2011). Besides, the ratio of organic carbon (OC) to elemental carbon (EC) was also used to distinguish BB to other emission sources, such as coal combustion and traffic (Chow et al., 2004;Lee et al., 2011Lee et al., , 2016Chuang et al., 2014). ...
... Various studies suggested that the Delta-C, the difference between ultraviolet black carbon (UVBC, 370 nm) and black carbon at 880 nm (BC), can be considered as an indicator of BB (Allen et al., 2004;Huang et al., 2011;Wang et al., 2010Wang et al., , 2011. It was further found that the concentrations and correlations between PBM and Delta-C were enhanced during the BB episode at three sampling sites in Northern New York, and during winter wood combustion episode in Huntington forest and Rochester, suggesting PBM and Delta-C could simultaneously be emitted from BB Wang et al., 2010). ...
... Recently, the Aethalometer model which utilizes the light-absorbing signals of aerosol at multi-wavelength has been developed for source apportionment studies, especially for BB identification (Civerolo et al., 2014;Huang et al., 2011;Martinsson et al., 2017;Sandradewi et al., 2008;Wang et al., 2010Wang et al., , 2011. Studies suggested that the Delta-C, the difference between ultraviolet black carbon (UVBC, 370 nm) and black carbon at 880 nm (BC), can be considered as an indicator of BB (Allen et al., 2004;Wang et al., 2010Wang et al., , 2011. ...
Thesis
Global anthropogenic emission inventories indicated that Asia is the region with the greatest proportion of anthropogenic mercury (Hg) emissions to the atmosphere, particularly in East and Southeast Asia. In addition, recent observation and modeling studies suggested that tropical forest areas may be hotspots of atmospheric Hg depositions. However, long-term studies on atmospheric Hg concentration and deposition in these regions are still quite limited. This work, for the first time, presents and analyzes the long-term observation of speciated atmospheric Hg, wet and dry deposition of atmospheric Hg at Lulin Atmospheric Background Station (LABS), a high mountain tropical forest site downwind of the East Asian continent. Nighttime (0–8 am) data of gaseous elemental Hg (GEM), which is more representative of regional influence, between April 2006 and December 2016 were used for trend analysis. Significant decreasing trends in GEM concentrations at LABS were observed, in agreement with the reductions in atmospheric Hg export from the East Asia continent that has been suggested by recent studies. Changes in the frequency distribution of air mass origins and transport paths may also contribute to the changes in GEM concentrations at LABS. Besides, the decreasing trends observed with air from the ocean indicated declining background GEM concentrations in Northern Hemisphere. Multi-year of dry and wet Hg depositions at LABS were studied. The dry/wet deposition ratio of 2.8 was observed, indicating that Hg deposition to forest landscape was governed by dry rather than a wet deposition. Both dry and wet Hg depositions at LABS were higher than those reported from the temperate region, suggesting that tropical forest mountains in East and Southeast Asia could be hot spots of atmospheric Hg deposition. Rainfall amount and rainfall types were the important factors in determining the seasonal distribution of wet Hg deposition. On the other hand, the seasonal distribution of dry Hg deposition was controlled by atmospheric Hg concentrations, temperature, and wind speed. GEM was the major dry deposition contributor at LABS, suggesting the important role of vegetation activity in forest ecosystems due to the uptake of Hg(0) by foliage. One-year observation data of total gaseous mercury (TGM) isotopic compositions were used to investigate the drivers responsible for the variation of TGM isotopic compositions at LABS. The results indicated that the variability of δ202HgTGM was attributed to vegetation activity, whereas the seasonal variation of ∆199HgTGM was likely driven by the seasonal changes in air mass origins and transport paths. This study, therefore, provides observational evidence for the role of vegetation activity at LABS.
... Summer 2006 was the warmest season during the entire study with an av-erage temperature of 19 • C (p < 0.001), and also similar to spring 2006, one of the lowest relative humidity levels (67 %, p < 0.02). The higher PHg concentrations in the winter at the ELA site were consistent with other remote and rural studies, which suggested that this observation was related to increased emissions from coal and wood combustion in winter, condensation of gases on atmospheric particles at lower temperatures, and re-suspension of particles during windy conditions (Choi et al., 2008;Huang et al., 2010Huang et al., , 2011. In urban settings, the summer maximum in PHg has been attributed to higher PM 2.5 concentrations in the summer, which provides more surface area for Hg absorption (Huang et al., 2010). ...
... The pollutants with the most influence on this factor represent transport of industrial emissions or regional background pollution, as observed previously using correlation analyses. The presence of K + in PCA-1 indicates wood combustion and biomass burning (e.g., wildfires) are potential sources, but this needs to be confirmed with other pollutant markers, such as carbon measurements (Choi et al., 2008;Huang et al., 2010Huang et al., , 2011 or levoglucosan (Watson et al., 2008). ...
... The transport of industrial emissions as previously described was also apparent in KCA-3, which had high mean values for GEM, HNO 3 , K + , NH + 4 , NO − 3 , and SO 2− 4 . The elevated K + and GEM concentrations may be attributed to wildfires and wood combustion (Watson et al., 2008;Huang et al., 2011). KCA-4 had elevated mean cluster centres for PHg, SO 2 , HNO 3 , Ca 2+ , Mg 2+ , K + , NH + 4 , NO − 3 , and SO 2− 4 , which is similar to some of elevated components in KCA-2. ...
... A significant negative trend was found for the VT99 site, and a marginally significant increasing trend was found for the NY20 site (p = 0.051) from 2005 to 2014 (Table 1). Higher monthly PBM concentrations were found in winter at both sites ( Figure S2), suggesting local/regional wood burning was a significant source of PBM 24 and reflecting increased condensation of gas phase mercury onto particles during colder seasons. 25 Particle mass concentration trends from 2005 to 2014 were found to be −1.75 and −1.77%/year for VT99 and NY20, respectively. ...
... The positive trends at the two sites may be related to increases in local wood burning emissions over time because local wood burning in winter is a source of PBM. 24 35 The change is also consistent with Figures S8 and S9 that show that mercury emissions generally declined over the period of 2005−2014 in regions west of the sites but stayed relatively high north of the sites (e.g., in the Montreal region). Forest fires have also been shown to be a source of PBM in this region, although those are mostly associated with late spring and summer months. ...
... A significant negative trend was found for the VT99 site, and a marginally significant increasing trend was found for the NY20 site (p = 0.051) from 2005 to 2014 (Table 1). Higher monthly PBM concentrations were found in winter at both sites ( Figure S2), suggesting local/regional wood burning was a significant source of PBM 24 and reflecting increased condensation of gas phase mercury onto particles during colder seasons. 25 Particle mass concentration trends from 2005 to 2014 were found to be −1.75 and −1.77%/year for VT99 and NY20, respectively. ...
... The positive trends at the two sites may be related to increases in local wood burning emissions over time because local wood burning in winter is a source of PBM. 24 PBM concentration trends were positive during all seasons at NY20 35 The change is also consistent with Figures S8 and S9 that show that mercury emissions generally declined over the period of 2005−2014 in regions west of the sites but stayed relatively high north of the sites (e.g., in the Montreal region). Forest fires have also been shown to be a source of PBM in this region, although those are mostly associated with late spring and summer months. ...
Article
Long-term atmospheric mercury measurements at Underhill, VT (VT99) and Huntington Forest, NY (NY20) from 1992 to 2014 and 2005 to 2014, respectively, were used to determine concentration trends using the Mann-Kendall’s tau test with Sen’s slope estimator. These data, measured generally downwind of large Hg sources in the Midwestern U.S., are the longest record of ambient Hg concentrations available in the U.S. At VT99 concentrations of gaseous element mercury (GEM), gaseous oxidized mercury (GOM) and particle bound mercury (PBM) declined with rates of -1.8%, -3.2% and -6.7% per year, respectively. At NY20 GEM and GOM concentrations declined at -1.6% and -7.8% per year, however, PBM concentrations increased at 2.0% per year likely related to winter wood burning. A trajectory ensemble analysis using potential source contribution function indicates the source locations associated with high mercury concentration changed from Toronto-Buffalo and Pennsylvania areas to east-coast urban centers. The declining GEM concentrations in the Northeastern United States are positively correlated with decreasing SO2 emissions in the upwind area. Overall, the results indicate that decreased mercury concentrations measured during the past decade are consistent with decreased Hg emissions from regional point sources and that increasing global emissions have not overwhelmed those decreases.
... Biomass burning and industrial emissions appear to exhibit individual ranges of ΔTGM/ΔCO slopes. The slopes for biomass burning plumes by ground or aircraft measurements are in the range of 0.9-3.1 × 10 À7 [Brunke et al., 2001;Ebinghaus et al., 2007;Friedli et al., 2003aFriedli et al., , 2003bHuang et al., 2011;Sigler et al., 2003;Weiss-Penzias et al., 2007]. Friedli et al. [2004] reported an ΔTGM/ΔCO slope of 6.4 × 10 À6 in the industrial plume from Shanghai. ...
... Comparison of ΔTGM/ΔCO slopes from biomass burning obtained from laboratory boiler experiments[Huang et al., 2011], intensive airborne campaigns using a small aircraft (a is from Friedli et al.[2003b]; b is from Friedli et al. [2003a]), onboard passenger aircraft (c is from Ebinghaus et al. [2007]; d is from Slemr et al. [2014]), and ground sites (e is from Brunke et al. [2001]; f is from Sigler et al. [2003]; g is from Weiss-Penzias et al. [2007] and this study). Backward trajectories of air masses associated with (a) ΔTHg/ΔCO ≥ 3.2 × 10 À6 (Events A and E), (b) 1.0 × 10 À6 ≤ ΔTHg/ΔCO ≤ 2.0 × 10 À6 (Events B, F, G, M, N, and O), (c) 5.1 × 10 À7 ≤ ΔTHg/ΔCO ≤ 9.0 × 10 À7 (Events C, D, and L), and (d) 2.0 × 10 À7 ≤ ΔTHg/ΔCO ≤ 6.0 × 10 À7 (Events H, I, J, K, P, Q, and R). ...
Article
Biomass burning from the Indo-China Peninsula region is an important source of atmospheric mercury (Hg). We isolated eighteen unique transport events over 2 years using observations of Hg and CO at a high-altitude background site in southwestern China (Mt. Ailao Observatory Station) to assess the transport and impact of Hg emissions from biomass burning. The quantity of Hg emission and the source regions were determined using ΔTGM/ΔCO slopes coupled with backward trajectory analysis and CO emission inventories. The slopes of ΔTGM/ΔCO appeared to be a useful chemical indicator for source identification. Industrial emission sources exhibited slopes in the range of 5.1-61.0 × 10−7 (pptv/pptv), in contrast to a slope of 2.0-6.0 × 10−7 for typical biomass burning. Transboundary transport of Hg from biomass burning led to episodically elevated atmospheric Hg concentrations during springtime. Hg emissions from biomass burning in the Indo-China Peninsula region from 2001 to 2008 were estimated to be 11.4 ± 2.1Mg yr−1, equivalent to 40% of annual anthropogenic emissions in the region. In addition, Hg emissions from biomass burning contained a substantial fraction of PBM. Assuming that PBM readily deposits locally (within 50 km), the local Hg deposition caused by the PBM was estimated to be 2.2 ± 0.4 Mg yr−1, up to 1 order of magnitude higher than the PBM deposition caused by anthropogenic emissions during springtime in the region. The strong springtime emissions potentially pose a threat to the ecosystems of the Indo-China Peninsula and southwest China.
... The mercury is a highly toxic substance to humans, ecosystems and wildlife; high doses can be fatal, but even relatively low doses can damage the nervous system [87]. It is being reported that three mercury (Hg) type contaminations [87] can occur in combustion of biomass (i) gaseous elemental mercury (GEM), (ii) gaseous oxidised mercury (GOM), and (iii) fine particulatebound mercury (PBM 2.5 ). ...
... The mercury is a highly toxic substance to humans, ecosystems and wildlife; high doses can be fatal, but even relatively low doses can damage the nervous system [87]. It is being reported that three mercury (Hg) type contaminations [87] can occur in combustion of biomass (i) gaseous elemental mercury (GEM), (ii) gaseous oxidised mercury (GOM), and (iii) fine particulatebound mercury (PBM 2.5 ). A peculiar characteristic of mercury is that, it exists in the environment in a number of different chemical and physical forms, each with different behaviour in terms of transport and environmental effects [88]. ...
Article
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Application of renewable energy technology is essential for achieving zero carbon buildings within the timescale envisaged by the UK government and the EU because the carbon intensity of the grid will still be high (well above 70% of current level) by 2016 and 2019. The biomass is a key renewable energy source, but its use in buildings is often affected by the emission of particulates and other pollutants in the waste gas, resulting in significant resistant to the technology by building users. The proposed research investigated various ways of removing pollutants, from the exhaust gas of biomass boilers. The review of literature shows that low cost and low maintenance technologies e.g. cyclones are preferred choices however they come with some limitation in removal of particulates. Recent advances in flue gas cleaning came with novel hybrid solutions to overcome traditionally used technologies for flue gas cleaning. Use of electrostatic preceptors with combination of other technologies is one example. The study found that it is difficult to obtain high removal efficiency for smaller particle range and require combination of technologies and improved hybrid solutions.
... This result may be due to Rochester's proximity to coal-fired power plants in Dunkirk and Tonawanda, NY and the upwind Midwestern coal-fired power plants. In addition, increasing residential woodburning during winter has been shown to increase the PBM concentrations (Choi et al., 2013;Huang et al., 2011). ...
... These patterns are likely related to seasonal patterns in emissions (more wood combustion associated with space heating around the Rochester and Potsdam in winter), shallower mixed layer heights during the colder months, and surface uptake primarily by leaves during the growing season (Choi et al., 2013;Xue Yu et al., 2013). Enhanced photochemical oxidation of GEM during the warmer months is also likely related to lower GEM concentrations in summer consistent with higher ozone concentrations in spring and summer (Huang et al., 2011). Additionally, GEM emissions from melting snow also contributed to higher GEM concentrations in winter and spring (Huang et al., 2010). ...
Article
Measurements of ambient speciated mercury (Hg) concentrations and Hg wet deposition were made at two urban sites (Bronx, NY and Rochester, NY) and one rural site (Potsdam, NY) in New York State in 2013 and 2014 to: 1) determine the factors influencing Hg wet deposition concentrations, 2) identify the contribution of gaseous oxidized Hg (GOM) and particulate bound Hg (PBM) scavenging to Hg wet deposition concentrations, and 3) identify potential source areas associated with high concentration events. The Bronx had the highest mean gaseous elemental Hg (GEM) and GOM concentrations, Rochester had the highest mean PBM and the lowest GOM concentrations, and Potsdam had the lowest mean GEM and PBM concentrations. The annual volume weighted mean (VWM) Hg concentrations and Hg wet deposition fluxes in the Bronx, Rochester, and Potsdam were significantly different with mean values of 10.3 ± 8.16, 10.2 ± 9.06, and 5.07 ± 1.79 ngL-1 and 8.45 ± 0.64, 6.65 ± 0.21, and 5.25 ± 0.49 μg/m2 year-1, respectively. Hg wet deposition flux and precipitation depth were positively correlated at all three sites as were Hg concentration in precipitation and weekly GOM concentrations at the Bronx and Potsdam sites. Scavenging coefficients (SC) of 680, 630, 850 for GOM and 410, 320, and 410 for PBM at Bronx, Rochester, and Potsdam, respectively, suggest GOM is responsible for most of the scavenged Hg. Measured GOM and PBM concentrations were relatively constant before precipitation events and Hg concentrations in precipitation did not vary significantly during precipitation events implying the scavenging process mainly occurred in clouds. VWM Hg concentrations, monthly accumulated Hg flux, and SCs for GOM and PBM were higher at the urban sites and significantly different for non-snow and snow events. Local sources appeared more important at the rural site while regional sources affected high urban concentrations.
... Concentrations of PBM are generally higher during the colder seasons, attributable to emissions related to space heating, a tendency for reactive Hg to partition from the gas-phase to particle phase at lower temperatures (Rutter and Schauer, 2007), and more shallow PBL depths. Wood smoke is a potential source of PBM in this region of the US (e.g., Choi et al., 2008;Huang et al., 2011), and this will be discussed in a later section. On the highest PBM days in March 2013, 48-hour back trajectories (not shown here) tended to originate from northern Canada, but we are not aware of any large forest fires that were occurring in this region. ...
... As noted earlier, smoke from residential wood combustion can impact the Rochester site during the colder months when wind speeds are low. A previous laboratory combustion chamber and field study found that combustion of wood or wood pellets can be an important source of GEM and PBM in northern climates in the winter (Huang et al., 2011). The panels in Fig. 10 show (a) PBM and GEM, (b) wind speed and direction, and (c) temperature from the Rochester site during a six-day period in November 2010. ...
Article
Full-text available
Since 2008, ambient speciated mercury (Hg) concentrations and weekly Hg wet deposition have been measured at two urban locations in New York – Rochester and New York City (borough of Bronx). These measurements were initiated to establish ambient Hg baselines ahead of anticipated emissions reductions, as well as characterize air concentrations and deposition at two different urban settings. In this paper seasonal and regional patterns in Hg wet deposition are presented, as well as seasonal, day of week and diurnal patterns in ambient Hg species at these two sites. The mean (and median) Hg concentration in precipitation was 9.56 ng/L (8.37 ng/L) at the Bronx site, and 9.95 ng/L (8.30 ng/L) at Rochester. Mean ambient air concentrations of gaseous elemental Hg (GEM), reactive gaseous Hg (RGM), and particle-bound Hg (PBM) at the Bronx and Rochester sites were 1.52 and 1.40 ng/m3, 6.26 and 8.24 pg/m3, and 7.96 and 13.48 pg/m3, respectively. Conditional probability function analysis was used to examine potential source regions impacting these two sites. Using these data we were able to examine monthly and diurnal patterns in speciated ambient Hg; however, more research is needed to more fully characterize potential emission sources that impact these sites.
... The seasonally averaged PBM concentrations ranged from 3.8 to 28.2 pg m À3 with the highest in winter and lowest in summer (June–August). Greater PBM concentrations in winter compared to other seasons may have resulted from increased emissions from fuel combustion, particularly wood for space heating (Friedli et al., 2003; Huang et al., 2011 ), poorer atmospheric mixing conditions, and increased sorption of semivolatile compounds including GOM at lower temperatures (Matsunaga et al., 2003; Rutter and Schauer, 2007a). This seasonal variation is consistent with previous studies (Liu et al., 2007Liu et al., , 2010 Engle et al., 2010; Huang et al., 2012)Table 1. ...
... A substantial number input of 10–100 nm particles was found in the nucleation factor. Delta-C and PBM are two indicators for wood combustion (Huang et al., 2011; Wang et al., 2011d), and factor 4 contributed 98% and 48%, respectively, of these species. Thus, this factor is classified as wood combustion, which was dominant in the winter and least important in the summer. ...
... PBM concentrations were in the order of NY43 > VT99 > MD08 > NY20 with the same seasonal pattern (winter > spring > summer $ fall) which is probably due to wood combustion for space heating in winter. 40,41,43,56 Seasonal and spatial pattern of Hg wet deposition ...
Article
Full-text available
Wet deposition is an important atmospheric mercury (Hg) pathway between air and terrestrial ecosystems. It is measured at numerous locations in the United States (U. S.) as part of the Mercury Deposition Network (MDN). The annual Hg wet deposition flux in 2009 at four locations in the northeastern U. S. (MDN sites MD08, VT99, NY20, and NY43) ranged from 6.4 to 13.4 μg per m(2) year which is higher than modeled reactive Hg (RM) dry deposition for this region. The highest ambient RM concentrations were seen at MD08, which is closest to significant anthropogenic sources; however, the volume-weighted mean Hg concentrations in precipitation were similar at these four sites. Mass based scavenging ratios (SC) of RM ranged from 1700 to 4500. Differences in SCs were likely a result of differences in meteorological conditions, the forms of RM in the atmosphere, vertical concentration variations, and measurement uncertainties, including precipitation depth and RM concentrations. RM SCs were higher than those reported for other soluble species. Multiple linear regression suggests that gaseous oxidized Hg is responsible for the majority of the scavenged RM.
... One reason for the higher %CPBM and %FPBM at rural-remote locations is the higher air concentrations of FPBM and CPBM, which may be attributed to nonpoint sources such as wood burning and forest fires [Y. Huang et al., 2011]. ...
Article
Relative contributions to mercury wet deposition by gaseous oxidized mercury (%GOM) and fine and coarse particle-bound mercury (%FPBM and %CPBM) were estimated making use of monitored FPBM air concentration and mercury wet deposition at nine North American locations. Scavenging ratios of particulate inorganic ions (K+ and Ca2+, Mg2+ and Na+) were used as a surrogate for those of FPBM and CPBM, respectively. FPBM and CPBM were estimated to contribute 8–36% and 5–27%, respectively, depending on the location, to total wet deposition. The rest of the 39–87% was attributed to the contribution of GOM. The average %GOM, %FPBM and %CPBM among all locations were 65%, 17%, and 18%, respectively. The relative distributions of %GOM, %FPBM, and %CPBM were influenced by Hg(II) gas-particle partitioning, urban site characteristics, and precipitation type. At the regional scale, %GOM dominated over %FPBM and %CPBM. However, the sum of FPBM and CPBM contributed to nearly half of the total Hg wet deposition in urban areas, which was greater than other site categories and is attributed to higher FPBM air concentrations. At four locations, %FPBM exceeded %GOM during winter in contrast to summer, suggesting the efficient snow scavenging of aerosols. The results from this study are useful in improving mercury transport models since most of these models do not estimate CPBM, but frequently use monitored mercury wet deposition data for model evaluation.
... There are no widely accepted measurement techniques for Hg dry deposition even though progress has been made using surrogate surfaces (Lyman et al., 2007;Marsik et al., 2007;Lai et al., 2011;Huang et al., 2011) and micrometeorological methods (Lindberg et al., 2002;Poissant et al., 2004). Dry deposition measurements of Hg often have large uncertainties due to the very low air concentration of Hg II and PHg, the uncertainties associated with the use of surrogate surfaces, the small vertical gradients in its concentration, and the effects of fast chemical reactions and advection from local sources . ...
Article
In this study, the size distributions of atmospheric particulate mercury (PHg) were measured in both urban and rural areas during the summer, fall, and winter. Both PHg concentrations and the contribution of PHg to total PM aerosol were higher at the urban (PHg = 6.8 ± 6.5 pg m−3, PHg/total PM = 0.18 pg μg−1) than at the rural site (PHg = 4.6 ± 2.7 pg m−3, PHg/total PM = 0.06 pg μg−1). Based on size-distribution measurements, the fine mode was the dominant size at both sites in winter while the coarse mode became more important during summer. In winter PHg concentrations in the fine mode increased because of the effective adsorption of gaseous Hg onto the fine particles at the low temperature and increased Hg oxidation reactions in the presence of high particles concentrations. During winter elevated concentrations of total PHg were measured when the prevailing winds were northwesterly originating in China.
... Ambient concentrations of speciated mercury showed distinct annual cycles with maximum values in spring and winter for GEM (1.47 ng m À3 ), in spring for GOM (3 pg m À3 ), and in winter for PBM (9 pg m À3 ) and with minimums in summer for GEM (1.1 ng m À3 ) and GOM (0.3 pg m À3 ) and in fall for PBM (2 pg m À3 ) ( Fig. 9). For the same monitoring site, similar patterns of temporal variations in GEM, GOM, and PBM were shown in Choi et al. (2008), Huang et al. (2011, and Choi et al. (2013), and higher concentrations of GEM in winter were attributed to lower PBL height, melting snow, and wood combustion for space heating. No trend was evident in GEM and a decreasing trend in GOM was found at a rate of À0.14 pg m À3 yr À1. ...
Article
Measurements of atmospheric particulate mercury (PHg) were conducted at a suburban site in Jinan, China from June 2014 to December 2015. The average PHg concentration was 508.5±402.7pgm(-3), and the average Hg content in PM2.5 (particles with a diameter of 2.5μm or less) was 6.60±5.82μgg(-1). Both PHg and Hg content in PM2.5 aerosols were comparable to levels in some cities in China and were much higher than in cities in North America and Europe. Weak correlations were found between PHg and meteorological parameters. The correlations between PHg and other pollutants in ambient air, including SO2, CO and NOχ, together with their wind dependence were used for source analysis, which suggested coal-fired industries, cement plants and traffic emissions as potential local sources for the site. Cluster analysis of 36-h backward trajectories suggested that the regional transport from southwestern Shandong Province also contributed to PHg in Jinan.
... Usually, there is no APCD for biomass burning. Huang et al. (2011) tested four different types of wood fuels and found the Hg 0 proportion to be 95-99 % and the rest is basically Hg 2+ . found that Hg 0 in flue gas from biomass burning is 70-90 % of total mercury while that of Hg 2+ ranges from 5 to 9 %. ...
Article
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Mercury transformation mechanisms and speciation profiles are reviewed for mercury formed in and released from flue gases of coal-fired boilers, non-ferrous metal smelters, cement plants, iron and steel plants, waste incinerators, biomass burning and so on. Mercury in coal, ores, and other raw materials is released to flue gases in the form of Hg0 during combustion or smelting in boilers, kilns or furnaces. Decreasing temperature from over 800 °C to below 300 °C in flue gases leaving boilers, kilns or furnaces promotes homogeneous and heterogeneous oxidation of Hg0 to gaseous divalent mercury (Hg2+), with a portion of Hg2+ adsorbed onto fly ash to form particulate-bound mercury (Hgp). Halogen is the primary oxidizer for Hg0 in flue gases, and active components (e.g., TiO2, Fe2O3, etc.) on fly ash promote heterogeneous oxidation and adsorption processes. In addition to mercury removal, mercury transformation also occurs when passing through air pollution control devices (APCDs), affecting the mercury speciation in flue gases. In coal-fired power plants, selective catalytic reduction (SCR) system promotes mercury oxidation by 34–85 %, electrostatic precipitator (ESP) and fabric filter (FF) remove over 99 % of Hgp, and wet flue gas desulfurization system (WFGD) captures 60–95 % of Hg2+. In non-ferrous metal smelters, most Hg0 is converted to Hg2+ and removed in acid plants (APs). For cement clinker production, mercury cycling and operational conditions promote heterogeneous mercury oxidation and adsorption. The mercury speciation profiles in flue gases emitted to the atmosphere are determined by transformation mechanisms and mercury removal efficiencies by various APCDs. For all the sectors reviewed in this study, Hgp accounts for less than 5 % in flue gases. In China, mercury emission has a higher Hg0 fraction (66–82 % of total mercury) in flue gases from coal combustion, in contrast to a greater Hg2+ fraction (29–90 %) from non-ferrous metal smelting, cement and iron and/or steel production. The higher Hg2+ fractions shown here than previous estimates may imply stronger local environmental impacts than previously thought, caused by mercury emissions in East Asia. Future research should focus on determining mercury speciation in flue gases from iron and steel plants, waste incineration and biomass burning, and on elucidating the mechanisms of mercury oxidation and adsorption in flue gases.
... From late fall to early spring, wood fired stoves are frequently used in Reno, NV, and an inversion layer often occurs due to topography. Huang et al. 49 reported, when using a Tekran system, that PBM was the dominant form of RM measured and suggested that wood combustion for space heating in winter was important. Since PBM is thought to be decomposed at higher temperatures than GOM, 13 and little residual GOM (digested membranes after desorption 0.26 ± 0.13, n = 9; blanks 0.29 ± 0.23 ng, n = 7; total 4 sets of data, 2 for HI and 2 for the MBL site) was measured on the membranes, this suggests that a different form of GOM than permeated in the laboratory was present in the air. ...
Article
The chemical compounds that make up gaseous oxidized mercury (GOM) in the atmosphere, and the reactions responsible for their formation, are not well understood. The limitations and uncertainties associated with the current method applied to measure these compounds, the KCl-coated denuder, are not known due to lack of calibration and testing. This study systematically compared the uptake of specific GOM compounds by KCl-coated denuders with that collected using nylon and cation exchange membranes in the laboratory and field. In addition, a new method for identifying different GOM compounds using thermal desorption is presented. Different GOM compounds (HgCl2, HgBr2, and HgO) were found to have different affinities for the denuder surface and the denuder underestimated each of these compounds. Membranes measured 1.3 to 3.7 times higher GOM than denuders in laboratory and field experiments. Cation exchange membranes had the highest collection efficiency. Thermodesorption profiles for the release of GOM compounds from the nylon membrane were different for HgO versus HgBr2 and HgCl2. Application of the new field method for collection and identification of GOM compounds demonstrated these vary as a function of location and time of year. Understanding the chemistry of GOM across space and time has important implications for those developing policy regarding this environmental contaminant.
... Ambient concentrations of speciated mercury showed distinct annual cycles with maximum values in spring and winter for GEM (1.47 ng m À3 ), in spring for GOM (3 pg m À3 ), and in winter for PBM (9 pg m À3 ) and with minimums in summer for GEM (1.1 ng m À3 ) and GOM (0.3 pg m À3 ) and in fall for PBM (2 pg m À3 ) ( Fig. 9). For the same monitoring site, similar patterns of temporal variations in GEM, GOM, and PBM were shown in Choi et al. (2008), Huang et al. (2011, and Choi et al. (2013), and higher concentrations of GEM in winter were attributed to lower PBL height, melting snow, and wood combustion for space heating. No trend was evident in GEM and a decreasing trend in GOM was found at a rate of À0.14 pg m À3 yr À1. ...
Article
An analysis of weekly measurement data of mercury (Hg) wet deposition was conducted for Huntington Wildlife Forest (HWF), a forest ecosystem in Upstate New York and a biological Hg hotspot, during 2000–2015. Annual accumulated Hg wet deposition flux was found to decrease at a rate of −0.13 μg m⁻² yr⁻¹ (2% yr⁻¹) (p = 0.09), and volume weighted mean (VWM) Hg precipitation concentrations at −0.14 ng L⁻¹ yr⁻¹ (2.5% yr⁻¹) (p = 0.00). In examining data by season, no trends were identified for the two variables. It was found that the North Atlantic Oscillation (NAO) affected Hg wet deposition predominantly in spring, as did the position of the U.S. East Coast trough in summer, which suggests different dominant mechanisms driving Hg wet deposition in different seasons. The impacts of such large scale circulation processes were facilitated via variations in precipitation amounts. This was manifested in spring 2011 with the strongest positive phase of NAO, resulting in the wettest spring with the largest Hg wet deposition flux, and in summer 2007 with the U.S. East Coast trough positioned the farthest out over the Atlantic Ocean, causing the driest summer with the lowest Hg wet deposition flux of the study period. Extreme precipitation amounts in spring could singularly drive the overall long-term trend in Hg wet deposition whereas in summer other factors could just be as important. Similar mechanisms were thought to control the long term variations of Hg wet deposition and precipitation concentrations in all seasons but summer as indicated in their significant correlation in all but summer. Atmospheric concentrations of gaseous oxidized mercury (GOM) and particulate borne mercury (PBM) at HWF over 2009–2015 hardly exhibited correlations with Hg wet deposition or precipitation concentrations. Chemical transport model simulations strongly supported efficient scavenging of oxidized Hg by precipitation resulting in the lowest concentration of GOM in the warm season despite the supposedly largest GOM production. Our findings suggest that over the long run climate change could play an important role in atmospheric deposition of Hg into ecosystems facilitated by precipitation amounts, which is closely linked to variations in large scale circulation.
... Median Hg concentrations in house dust from homes using only one fuel type showed the following trend: wood > oil > electricity > natural gas (Figure 1), suggesting that wood combustion exerts the greatest influence. This interpretation is consistent with experimental research showing that wood combustion is a source of oxidized mercury (mostly in the particulate phase) in northern climates in winter [102]. The median Hg concentration for the entire dataset (690 ng/g; n = 995; [55]) is exceeded by the medians for homes heated solely by wood (860 ng/g; n = 27), heating oil (720 ng/g; n = 32) or electricity (710 ng/g; n = 72). ...
Article
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This study investigates associations between house characteristics and chemical contaminants in house dust, collected under the nationally representative Canadian House Dust Study (2007–2010). Vacuum samples (<80 µm fraction) were analysed for over 200 synthetic organic compounds and metal(loid)s. Spearman rank correlations between contaminant concentrations in dust and presence of children and pets, types of flooring, heating styles and other characteristics suggested a number of indoor sources, pointing to future research directions. Numerous synthetic organics were significantly associated with reported use of room deodorizers and with the presence of cats in the home. Hardwood flooring, which is a manufactured wood product, emerged as a source of metal(loid)s, phthalates, organophosphate flame retardants/plasticizers, and obsolete organochlorine pesticides such as ∑DDT (but not halogenated flame retardants). Many metal(loid)s were significantly correlated with flame-retardant compounds used in building materials and heating systems. Components of heating appliances and heat distribution systems appeared to contribute heat-resistant chemicals and alloys to settled dust. Carpets displayed a dual role as both a source and repository of dust-borne contaminants. Contaminant loadings (<80 µm fraction) were significantly elevated in heavily carpeted homes, particularly those located near industry. Depending on the chemical (and its source), the results show that increased dust mass loading may enrich or dilute chemical concentrations in dust. Research is needed to improve the characterisation of hidden indoor sources such as flame retardants used in building materials and heating systems, or undisclosed ingredients used in common household products, such as air fresheners and products used for companion animals.
... A schematic of the sampling system is shown in Fig. 2. This sampling method has been used by other researchers (Cernuschi et al., 2012;Huang et al., 2011;Horak et al., 2017). ...
Article
A significant increase in the use of wood pellets for residential space heating has occurred over the past decade. The performance of two modern residential wood pellet boilers (designated PB and WPB) were evaluated including boiler thermal efficiency, thermal energy storage (TES) tank discharge efficiency, and system efficiency. A correlation applicable to both systems between the boiler thermal efficiency (ηth, in %) and the boiler output load (χ, in %) was found in the form of ηth = 52.69 ln χ – 137.7 with R2 = 0.79 (for 25 < χ < 75). This equation provides an easy, accurate estimation of the boiler thermal efficiency in field operations. The boiler thermal efficiency decreased with time and this decline was determined using a Mann-Kendall trend analysis with Sen’s slope. This decrease was primarily the result of fouling in the heat exchanger and thus, this analysis identifies the need for manual cleaning of the heat exchanger tubes to restore maximal system performance. The evaluation of the TES tank performance found that the TES tank discharge efficiency was correlated with a dimensionless function of tank inlet Reynolds number (Red) and temperature differences in the tank and inlet and outlet pipes. Overall system efficiency showed a seasonal average of 62.8%, 62.0%, and 75.8% for three heating seasons of the PB system. These results provide a comprehensive performance evaluation of these wood pellet boiler heating systems in the field over an extended period of operation.
... A schematic of the sampling system is shown in Fig. 2. This sampling method has been used by other researchers (Cernuschi et al., 2012;Huang et al., 2011;Horak et al., 2017). ...
Article
Effective biomass energy utilization for residential space heating relies on having combustion systems with both high efficiency and low emissions. European technology in wood pellet boilers was introduced into the United States over the past decade. However, these systems need to be designed and operated to minimize the emissions of air pollutants, particularly airborne particulate matter. One approach to minimize emissions is to improve system efficiency and limit the number of boiler cycles that include start-up and shut down periods where emission rates are higher by utilizing thermal storage as part of the boiler system. In this study, emissions from two 25 kW European-designed, but U.S. manufactured wood pellet boilers (PB and WPB) with thermal energy storage (TES) were measured in actual home operation using the EPA CTM-039 stack sampling method. These measurements allowed the estimation of the emissions reductions due to the presence of TES. PB had much higher emissions than WPB because PB had frequent local oxygen deficit-induced non-uniform combustion, which highlights the significance of periodic onsite oxygen tuning after the boiler installation. Particulate emissions were dominated by PM 2.5 and the particles mainly consisted of low melting point, alkali compounds such as K 2 SO 4 , KCl, Na 2 SO 4 , CaCl 2 , etc. Both PM 2.5 and polycyclic aromatic hydrocarbons (PAHs) emissions increased linearly with CO because they are products of incomplete combustion. Optimum boiler operating conditions were found with 12% flue gas oxygen content for both systems to achieve minimum CO emissions, which is 2% higher than the manufacturer's set-point of 10%. The potential emissions reductions by using a system with TES instead of a non-TES system were estimated under three scenarios. The results showed both significant gaseous and particulate matter emissions reductions that demonstrate that modern, high-efficiency wood pellet boilers with TES systems can produce heat with lower total emissions compared to non-TES systems.
... These two metals probably have a more remarkable environmental persistence, and more time could be needed for their decrease to appreciate the effects in the long term (T2 and T3) (Fig. 4). In addition, despite the reduction of industrial activities and urban traffic, the increase of atmospheric Hg emissions, as a consequence of intensive use of household appliances (e.g., boilers and heaters) throughout the lockdown, likely led to a different trend in the environmental occurrence of this metal (Huang et al., 2011;Cui et al., 2019 (see Fig. 5). ...
Article
The Covid-19 outbreak had a critical impact on a massive amount of human activities as well as the global health system. On the other hand, the lockdown and related suspension of working activities reduced pollution emissions. The use of biomonitoring is an efficient and quite recent tool to assess environmental pollution through the analysis of a proper bioindicator, such as bees. This study set out to ascertain the impact of the Covid-19 pandemic lockdown on the environmental occurrence of eleven heavy metals in the Campania region (Italy) by analyzing bees and bee products. A further aim of this study was the assessment of the Honeybee Contamination Index (HCI) in three different areas of the Campania region and its comparison with other Italian areas to depict the current environmental pollutants levels of heavy metals are concerned. The results showed that the levels of heavy metals bioaccumulated by bees during the pandemic lockdown (T1) were statistically lower than the sampling times after Covid-19 restrictions and the resumption of some or all activities (T2 and T3). A comparable trend was observed in wax and pollen. However, bee, pollen, and wax showed higher levels of Cd and Hg in T1 than T2 and T3. The analysis of the HCI showed a low contamination level of the sampling sites for Cd and Pb, and an intermediate-high level as regards Ni and Cr. The biomonitoring study highlighted a decrease of heavy metals in the environmental compartments due to the intense pandemic restrictions. Therefore, Apis mellifera and other bee products remain a reliable and alternative tool for environmental pollution assessment.
... 36 Mercury emissions in Basel, Zurich, or Toronto mainly originated from both diffuse and point sources. 9,36 Ambient GEM concentrations in cities are likely more variable, at least over short periods of time compared to background sites due to re-emission from buildings 19 and other artificial surfaces, 15 exhaust from heating, 38 and sinks (e.g., vegetation cover 39 ). The complex vertical and horizontal transport mechanism caused by urban structures like surface type or building height and micrometeorological conditions further contribute to the variability of GEM concentrations in urban environments. ...
Article
Full-text available
Indoor air pollution can be a major health risk because urban populations spend up to 90% of their time in closed rooms. Gaseous elemental mercury (GEM) has not been measured as routinely as other indoor air pollutants due to high costs and limited mobility of active Hg analyzers. However, household GEM concentrations may exceed Hg air quality guidelines as a result of potential indoor GEM sources like broken Hg thermometers. Here we deploy novel low-cost mercury passive air samplers (MerPAS) in 27 households (7 days) and at 14 outdoor locations (29–31 days) in Basel, Switzerland. Average Hg concentrations ranged from 2.0 to 10.8 ng m-3 indoors and from 1.8 to 2.5 ng m-3 outdoors. These results reveal that households are a net source of Hg to the urban atmosphere and exceed outdoor Hg levels by a factor of two in average. We estimated an average weekly intake rate of 0.01 µg Hg per kg of body weight for adult residents in Basel which is usually smaller than Hg exposure of people with dental amalgam fillings. Our campaign demonstrates that air monitoring programs can easily be complemented by straightforward Hg measurements using MerPAS.
... About 31% of the mercury in the air comes from biomass combustion. There are three types of mercury (Hg) pollution: gaseous elemental mercury (GEM), gaseous oxide mercuric (GOM), and fine particulate bound mercury (PBM 2.5 ) (Huang et al., 2011). Activated carbon adsorption has been demonstrated to be an effective method to remove Hg from flue gas, but this method is costly due to the need for expensive activated carbon materials. ...
Chapter
Extensive efforts have been made in the conversion of biomass into renewable energy using thermochemical and biochemical approaches. During biomass thermochemical conversion, nitrogen oxides (NOx), particulate matter (PM), and tar are the major environmental emissions generated. NOx and PM generated in thermochemical conversion processes can be effectively removed by existing technologies, and tar can be reduced through end treatment and in situ process control. In bioconversion of biomass, the major environmental emissions are volatile organic compounds (VOCs), sulfur-containing gases (e.g., H2S), wastewater, and biogas slurry. Biogas slurry can be utilized as a value-added resource, and wastewater and VOCs can be treated via physical-chemical or biological methods. From a green engineering perspective, the most effective approach is the source reduction of pollution, which can be achieved through process improvement/control or the development of new conversion processes. Employing emission treatment and source-reduction approaches, bioenergy-related environmental issues can be minimized. Developing new industrial technologies or processes that use biomass as a source of energy or chemicals is the future direction of clean production.
... The biocomposites seemed to be more thermal stable, because they had lower degradation rate than the poplar at a high temperature (600 • C). The mass loss of biocomposites prepared with 40-60 mesh wood powder was the lowest in the biocomposites prepared by wood powder with different particle sizes (Samaras et al., 2001;Huang et al., 2011). The DTG curve showed that the maximum degradation rate of the biocomposite was lower than the poplar. ...
Article
Green composite processing technology of wood fibers is an inevitable choice for global sustainable development. In this research, waste poplar powder with different particle sizes was used to prepare glue-free biocomposites with good mechanical and waterproof properties by hot-molding. The biocomposites made of larger size wood powder had better tensile strength (40.3 MPa) and the biocomposites made of smaller size wood powder had the greater bending strength (50.5 MPa). The thickness swelling rate of the biocomposites was only 4.26% after soaking in water for 24 h. The cross-section morphology of the biocomposites showed that the cell wall collapses enhanced the interfacial bonding. Chemical analysis showed that lignin repolymerized with cellulose and hemicellulose for the vitrification transition. In addition, the biocomposites with excellent mechanical properties had no formaldehyde release, which can replace the traditional density boards made of adhesives and applied as furniture materials and in line with the concept of cleaner production.
... Konsentrasi logam berat yang terlalu tinggi pada lingkungan perairan dapat menyebabkan dampak toksik bagi biota perairan. Merkuri (Hg) merupakan salah satu logam berat yang umumnya terdapat dalam limbah, misalnya dari hasil pembakaran (Huang et al., 2011), kegiatan industri batubara, pertambangan, limbah organik, dan berbagai kegiatan antropogenik lainnya (Fang & Chen, 2010;Liu et al., 2011). Merkuri (Hg) yang berasal dari limbah masuk ke perairan dalam bentuk anorganik dan dapat berubah secara alami dalam air dan sedimen menjadi senyawa toksik organik yaitu methylmercury (MeHg) yang dapat masuk ke organisme perairan (Mason et al., 2006;Voegborlo et al., 2011). ...
Article
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strong>Bioaccumulation of Mercury (Hg) in Seagrass Enhalus acoroides and Mangrove Rhizophora apiculata in Pari Island, Seribu Islands. Heavy metal pollution, especially Hg metal in Jakarta Bay, is feared to have a negative impact on the quality of the waters around the Jakarta Bay waters, one of which is Pari Island in the Thousand Islands. Seagrass and mangroves plants distributed surrounding Pari Island can be used as indicators of heavy metal pollution. The value of bioaccumulation and translocation of Hg metal factors will provide an overview of the ability of plants to accumulate heavy metals in their surroundings. This study aims to determine the bioaccumulation and translocation of the heavy metal Hg factor in Enhalus acoroides seagrass and Rhizophora apiculata mangroves on Pari Island, Seribu Islands. Seagrass and mangrove samples were taken at five sampling points through purposive sampling. The bioaccumulation value was calculated using the ratio of the metal concentrations in each part of the plant body and sediment. Meanwhile, the translocation factor value was calculated by the ratio of Hg concentration in each part of the plant body (roots/rhizomes, stems, and leaves). The results of this study indicate that the bioaccumulation value in seagrass is infinite (bioaccumulation factor, BAF=∞) and in mangroves is 1.57 (BAF>1). The highest translocation factor value in seagrass leaves is 3.86 (translocation factor, TF) >1) and in mangrove leaves is 2.84 (TF>1). This study shows that seagrass and mangrove plants are classified as good bio accumulator and hyperaccumulator plants and accumulate heavy metals, especially Hg in the upper part of their bodies, namely leaves
Article
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Source-receptor relationships for speciated atmospheric mercury measured at the Experimental Lakes Area (ELA), northwestern Ontario, Canada were investigated using various receptor-based approaches. The data used in this study include gaseous elemental mercury (GEM), mercury bound to fine airborne particles (<2.5 μm) (PHg), reactive gaseous mercury (RGM), major inorganic ions, sulphur dioxide, nitric acid gas, ozone, and meteorological variables, all of which were measured between May 2005 and December 2006. The source origins identified were related to transport of industrial and combustion emissions (associated with elevated GEM), photochemical production of RGM (associated with elevated RGM), road-salt particles with absorption of gaseous Hg (associated with elevated PHg and RGM), crustal/soil emissions, and background pollution. Back trajectory modelling illustrated that a remote site, like ELA, is affected by distant Hg point sources in Canada and the United States. The sources identified from correlation analysis, principal components analysis and K-means cluster analysis were generally consistent. The discrepancies between the K-means and Hierarchical cluster analysis were the clusters related to transport of industrial/combustion emissions, photochemical production of RGM, and crustal/soil emissions. Although it was possible to assign the clusters to these source origins, the trajectory plots for the Hierarchical clusters were similar to some of the trajectories belonging to several K-means clusters. This likely occurred because the variables indicative of transport of industrial/combustion emissions were elevated in at least two or more of the clusters, which means this Hg source was well-represented in the data.
Article
Tekran® Hg speciation systems were used at a rural site (Huntington Forest, NY; HF) and a suburban site (Rochester, NY; ROC) to measure gaseous elemental mercury (GEM), gaseous oxidized mercury (GOM), and fine particulate-bound mercury (PBM(2.5)) concentrations for two years (December 2007 to November 2009). Ancillary data were also available from the New York State Department of Environmental Conservation and the United States Environmental Protection Agency Clean Air Status and Trends Network. Seasonal GEM concentrations were similar at both sites and influenced by factors such as the planet boundary layer (PBL) height and mercury emissions from snow, soil, and point sources. In some seasons, O(3) was negatively correlated with GEM at ROC and positively correlated with GEM at HF. At HF, O(3) was correlated with GOM and was typically higher in the afternoon. The cause of this pattern may be photochemical reactions during the day, and the GOM diel pattern may also be due to deposition which is enhanced by dew formation during the night and early morning. PBM(2.5) concentrations were higher in winter at both sites. This is indicative of local wood combustion for space heating in winter, increased sorption to particles at lower temperatures, and lower PBL in the winter. At the suburban site, 2 of 12 events with enhanced GEM/CO ratios were poorly correlated with SO(2)/GOM, implying that these two events were due either to long range transport or regional metallurgical industries in Canada.
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The chemical composition of 23 wood chip samples and 132 wood pellet samples manufactured in the United States and Canada were analyzed for their energy and chemical properties and compared to German standards for pellet quality. The pellet samples obtained from various locations across northern New York and New England included 100 different manufacturers and duplicate samples of some brands. The calorific value, moisture content, and ash content of the samples were determined according to the American Society for Testing and Materials (ASTM) methods. Sulfate and chloride samples were prepared using ASTM methods and analyzed by ion chromatography (IC). The elemental compositions of the ashed wood samples were determined using inductively coupled plasma mass spectrometry (ICP-MS). Mercury was measured by direct analysis of wood samples. The distributions of the sample characteristics, such as heating value, ash content, moisture content, ions, and heavy elements, are presented. Major ash-forming elements were Ca, K, Al, Mg, and Fe. Although heavy elements are found naturally in wood and bark, some pellet samples had unusually high concentrations of heavy elements. This contamination was likely because of inclusion of extraneous materials, such as scrap or painted wood, bark or leaves, and other possible contaminants, during pellet manufacturing processes. Most of the commercially available wood pellets of this study would meet German and European industrial standards. However, standards for elemental compositions of commercial wood pellets and chips need to be established in the United States to exclude extraneous materials. The promulgation of such standards would reduce environmental problems related to air emissions and ash used as fertilizers for agriculture soils, where there are limits on the allowable concentrations for many elements.
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Two modified passive samplers were evaluated at multiple field locations. The sampling rate (SR) of the modified polyurethane foam (PUF)-disk passive sampler for total gaseous mercury (TGM) using gold-coated quartz fiber filters (GcQFF) and gaseous oxidized mercury (GOM) using ion-exchange membranes (IEM) were 6.4 AE 1.4 and 15.3 AE 0.3 m 3 day À1 , respectively. The relative percent difference between TGM and GOM concentrations measured by a Tekran system and the passive samplers averaged 19 AE 14 and 13 AE 12% and ranged between 4–44 and 1.5–41%, respectively. The GcQFF and IEM substrates were also evaluated as collection media for surrogate surface dry deposition measurements. Mercury (Hg) concentration and dry deposition gradients were observed using these samplers at an urban/industrial site and compared to a rural/remote site. The Hg dry deposition rates measured by the surrogate surfaces were always higher than those calculated by a widely used inferential modeling method (1.3–50 fold). The Hg dry deposition measured at urban and suburban sites were comparable to those calculated from model. However, they were very different at a rural site, probably due to the low concentrations. Both methods are relatively low cost and will aid in understanding spatial distributions of Hg ambient air concentrations and dry deposition.
Technical Report
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Pollution from domestic sources has become the focus of increasing research and regulatory attention in recent years. This is mainly because major efforts towards the reduction of certain emissions to air in the industrial sector have been successful , . Emissions of Persistent Organic Pollutants (‘POPs’) - most notably polychlorinated dibenzo-p-dioxins/polychlorinated dibenzofurans (“PCDD/PCDF” or, more commonly simply “dioxins”) and Polycyclic Aromatic Hydrocarbons (PAH’s) have been particularly important because of the serious health and environmental impacts. Overall emissions of dioxins to air have decreased considerably and the European inventory, for example, estimates that emissions of dioxin to air from legally operating waste incinerators fell from 4,000 grammes/year in 1985 to between 178 and 232 grammes/year in 2005 . The consequence is that domestic emissions to air now form a much higher proportion of the total emissions than was previously the case. As a result of this reduction of industrial emissions it is now commonly claimed that domestic burning of waste has far higher emission factors than waste incineration. The European Commission, for example, say that “One kg of waste openly burned may cause the same amount of dioxin emissions as 10 tonnes of waste burned in a modern incineration plant” . Reports from the Czech Republic claim that the emissions of dioxin from domestic combustion in a single village are similar to those from large incinerators . These claims are rather misleading as the emission factors relate only to air emissions and far more dioxins in modern incinerators partition to the ash residues than are emitted to air. These residues are commonly landfilled in sites which are not protective of the environment . In some countries, such as the Czech Republic, it is common practice to use residues from incineration in construction projects. The Stockholm Convention applies to emissions of POPs to all media and it is important that this is applied in practice when discussing different technologies and abatement techniques. It became clear at an early stage in this review that in comparison to emissions of POPs from municipal waste combustion, literature reports on emissions from small-scale biofuel and other domestic heating sources are scarce . The review by BiPRO for the European Commission reported 90 studies relating to the (then) current state of knowledge on dioxin releases from domestic sources. Only a small number of these were relevant to the specific concerns relating to the co-combustion of plastics or waste in domestic situations. This represents an important gap in the scientific literature given the apparent significance of domestic sources in the dioxin inventories relied upon by the European Commission and other policy makers. Ironically their consultants, BiPro, comment that “Dioxin emissions are currently not a driving force for environmental policy in the domestic sector".
Preprint
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Evidence of air pollution exposure, namely, ambient particulate matter (PM), during pregnancy and an increased risk of autism spectrum disorders (ASD) in children is growing. Which PM sources contribute to this association is currently unknown, however. The aim of the present study was to investigate local source-specific ambient PM exposure and its association with ASD. A cohort of 48,571 singleton births from 1999 to 2009 in Scania, Sweden, was combined with data on locally emitted PM with an aerodynamic diameter <2.5 µm (PM 2.5 ). A flat, two-dimensional dispersion model was used to model PM 2.5 exposure (all-source PM 2.5 , tailpipe exhaust, vehicle wear-and-tear, and small-scale residential heating- mainly wood burning) at the residential address. Associations were analyzed using binary logistic regression in partially and fully adjusted models. Clear associations were observed between PM 2.5 and ASD, with statistical significance for all investigated sources in the partially adjusted model. In the fully adjusted model, only all-source PM 2.5 was statistically significant. The results add to existing evidence that exposure to air pollution during pregnancy may be associated with an increased risk for ASD among children. Further, these findings suggest that locally emitted tailpipe exhaust, vehicle wear-and-tear, and small-scale residential heating all contribute to this association.
Article
Comparisons of mercury sources and atmospheric mercury processes were conducted between a coastal and inland site in northeastern North America. Identifying sources of atmospheric Hg is essential for understanding what is potentially contributing to Hg bioaccumulation at these two sites. A data set consisting of gaseous elemental mercury (GEM), gaseous oxidized mercury (GOM), particle-bound mercury, ozone, trace gases, particulate ions, and meteorological data were analyzed using principal components analysis (PCA), absolute principal component scores (APCS), and back trajectories. The PCA factors representing gaseous Hg condensation on particles during winter and combustion and industrial sources were found at both sites. However, the PCA factor for combustion/industrial sources was not found in 2010 at either site, likely because of SO2 emissions reductions from coal utilities from 2008 to 2010. Using APCS and back trajectories, the combustion/industrial factor at the coastal site was narrowed down to shipping ports along the Atlantic coast. Hg sources affecting coastal sites are different from those affecting inland sites because of the influence of marine airflows. GEM evasion from the ocean was evident from a PCA factor containing GEM, relative humidity, wind speed, and precipitation along with significantly higher contributions of this source (APCS) from oceanic trajectories compared to land/coastal trajectories. Analysis of the effects of ozone and water vapor mixing ratio on %GOM/total gaseous mercury suggest that Hg-Br photochemistry occurred at lower ozone concentrations (<40 ppb) at the coastal site and the absence of free troposphere transport of GOM.
Article
Among various sources, mercury emissions from biomass fuel combustion have received growing attention. Mercury emission from biomass fuels can be estimated on the basis of the combustion amount and the emission factors (EFs). Although mercury emissions from biomass fuel combustion occur mostly in developing countries, most EFs have been measured in developed countries, leading to bias in mercury emission inventories. In this study, mercury EFs for 25 species of fuelwood, eight species of crop residues, and two types of biomass pellets were determined according to the real-life practice of residential burning. Results showed that the EFs ranges were 0.65–28.44 ng g–1 for fuelwood, 3.02–12.05 ng g–1 for crop residues, and 5.22–8.10 ng g–1 for biomass pellets. Hg0 is the dominant form of mercury emitted from biomass fuel combustion. The proportion of Hg0, Hg2+, and Hgp was 76 ± 17, 6 ± 5, and 18 ± 14% for fuelwood; 73 ± 11, 4 ± 5, and 23 ± 13% for crop residues; and 97 ± 1, 1 ± 0.2, and 2 ± 0.7% for biomass pellets, respectively. Biomass pellets can reduce mercury emissions compared with the uncompressed raw materials. On the basis of the measured EFs, inventories of mercury emission from biomass fuel combustion in rural China from 2000–2007 were estimated. The annual mercury emission ranged from 1.94 to 5.07 Mg, of which crop residues and fuelwood accounted for 62 and 38%, respectively.
Article
We present the first real attempt to directly and continuously measure GEM through a Lumex RA-915 M, designed for real-time detection of mercury vapor, mounted on an UAV (Unmanned Aerial Vehicle, namely a heavy-lift octocopter), inside and outside the former Hg-mining area of Abbadia San Salvatore (Mt. Amiata, Italy), known as a GEM source. We tested the effectiveness of the UAV-Lumex combination at different heights in selected sites pertaining to both mining facilities and surrounding urban zones, shedding light on the GEM spatial distribution and concentration variability. The Lumex great sensitivity and the octocopter optimal versatility and maneuverability, both horizontally and vertically, allowed to depict the GEM distribution in the atmosphere up to 60 m above the ground. The acquisition system was further optimized by: i) synchronizing Lumex and UAV GPS data by means of a stand-alone GPS that was previously synchronized with Lumex; ii) using a vertical sampling tube (1.20 m high) connected to the Lumex inlet to overcome the rotors strong airflows and turbulence that would have affected GEM measurements; iii) supplying the octocopter with batteries for power supply to avoid the release of exhaust gases; iv) taking the advantage of the UAV ability to land in small spaces and stop at selected altitudes. The resulting dot-map graphical representations, providing a realistic 3D picture of GEM vertical profiling during the flights in near real-time, were useful to verify whether the guideline concentrations indicated by competent authorities were exceeded. The results showed that the GEM concentrations in the urban area, located a few hundred meters from the mining structures, and close to already reclaimed areas remained at relatively low values. Contrarily, GEM contents showed significant variations and the highest concentrations above the facilities containing the old furnaces, where increasing GEM concentrations were recorded at decreasing heights or downwind.
Article
In this investigation, the concentrations of gaseous elemental mercury (GEM), reactive gaseous mercury (RGM) and particulate bound mercury (PBM) in ambient air were measured at the Hung Kuang (traffic) sampling site during September 27 to October 6, 2014. An ambient air mercury collection system (AAMCS) was utilized to measure simultaneously PBM, GEM, and RGM concentrations in ambient air. The results thus obtained demonstrate that the mean concentrations of PBM, GEM, and RGM were 38.57 ± 11.4 (pg/m3), 17.67 ± 5.56 (ng/m3) and 10.78 ± 2.8 (pg/m3), respectively, at this traffic-sampling site. The mean GEM/PBM and GEM/RGM concentration ratios were 458 and 1639, respectively. The results obtained herein demonstrate that AAMCS can be utilized to collect three phases of mercury simultaneously. The mean PBM, GEM, and RGM concentrations herein were compared with others found in Asia, America, Europe and Antarctica. The mean PBM, GEM, and RGM concentrations were found to be lowest in Asia and Antarctica. The mean PBM concentration in Europe was approximately eight times that in this investigation. The mean GEM and RGM concentrations in this study were 1.21 and 170 times those found in the United States.
Article
Three coals were blended with soybean rod at 95:5, 90:10 and 85:15 mass ratios. The combustion experiments were conducted at 1250°C in a high temperature electrical reactor. The fly ashes were collected and the Hg contents were measured. The Hg contents and Hg emissions of unit calorific value (named calculated Hg content and calculated Hg emission) of the blended fuels were calculated. The results indicated that the ratio of Cl to Hg of the fuel increases with the increase of the soybean rod ratio while the ratio of Hg to ash doesn't change significantly. The increasing of the soybean rod ratio leads to an increase in both Hg content in ash and Hgp ratio for coal 1 while coal 2 and coal 3 are different. The Increase of the soybean rod ratio makes the calculated Hg content decrease but the calculated gaseous Hg emission is not definite.
Article
Rural lower Yakima Valley, Washington is home to the reservation of the Confederated Tribes and Bands of the Yakama Nation, and is a major agricultural region. Episodic poor air quality impacts this area, reflecting sources of particulate matter with a diameter of less than 2.5 μm (PM2.5) that include residential wood smoke, agricultural biomass burning and other emissions, truck traffic, backyard burning, and wildfire smoke. University of Washington partnered with the Yakama Nation Environmental Management Program to investigate characteristics of PM2.5 using 9 months of data from a combination of low-cost optical particle counters and a 5-wavelength aethalometer (MA200 Aethlabs) over 4 seasons and an episode of summer wildfire smoke. The greatest percentage of hours sampled with PM2.5 >12 μg/m³ occurred during the wildfire smoke episode (59%), followed by fall (23%) and then winter (21%). Mean (SD) values of Delta-C (μg/m³), which has been posited as an indicator of wood smoke, and determined as the mass absorbance difference at 375–880 nm, were: summer – wildfire smoke 0.34 (0.52), winter 0.27 (0.32), fall 0.10 (0.22), spring 0.05 (0.11), and summer – no wildfire smoke 0.04 (0.14). Mean (95% confidence interval) values of the absorption Ångström exponent, an indicator of the wavelength dependence of the aerosol, were: winter 1.5 (1.2–1.8), summer – wildfire smoke 1.4 (1.0–1.8), fall 1.3 (1.1–1.4), spring 1.2 (1.1–1.4), and summer – no wildfire smoke 1.2 (1.0–1.3). The trends in Delta-C and absorption Ångström exponents are consistent with expectations that a higher value reflects more biomass burning. These results suggest that biomass burning is an important contributor to PM2.5 in the wintertime, and emissions associated with diesel and soot are important contributors in the fall; however, the variety of emissions sources and combustion conditions present in this region may limit the utility of traditional interpretations of aethalometer data. Further research on the interpretation of aethalometer data in regions with complex emissions would contribute to much-needed understanding in communities impacted by air pollution from agricultural as well as residential sources of combustion.
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Mercury is a global neurotoxic pollutant, which can be globally transported and bioaccumulated in the food chain. Iron–steel production is one of the most significant sources of anthropogenic atmospheric mercury emission, while information on this source is scarce. Hourly gaseous elemental mercury (GEM) and particle bound mercury (PBM) were studied inside (IP) and at the boundary (BP) of a typical iron–steel plant in the Yangtze River Delta (YRD), China from September 2016 to August 2017. The GEM concentrations were 0.97–503.1 and 0.05–112.6 ng/m3 at the IP and BP sites, respectively, while PBM concentrations were one to four orders of magnitude higher than urban and suburban ambient levels. Several lines of evidences indicated that PBM was mainly originated from the iron–steel manufacturing process, especially from sintering and coke-making processes in this iron–steel plant. However, a combined emission effect contributed to GEM variation. The receptor model of positive matrix factorization (PMF) showed that local direct emissions (coal combustion, industrial activity, vehicle exhaust, and secondary evaporation from polluted soil) contributed 51.3% of the total GEM concentration variation. Potential source contribution function (PSCF) and concentration weighted trajectory (CWT) models clearly showed that air masses moving from areas surrounding YRD had the highest concentrations of atmospheric mercury. These results provided evidence that iron–steel manufacturing emissions have a considerable effect on regional atmospheric mercury concentrations, especially PBM.
Article
In this study, Hg isotopes, backward trajectory, and emission inventory were utilized to explore the effects of possible emission sources and photochemical pathways on fine-particle bound mercury during two single haze events in February 2017 and January 2018 at Gucheng (38.31°N, 115.25°E). Results showed that (a) the large variations of odd-mass mass-independent fractionation values in fine-particle bound mercury showed the joint contributions of different source regions during haze evolution; (b) biomass burning significantly contributed to fine-particle bound mercury during winter haze in northern China; (c) fine-particle bound mercury during haze evolution at Gucheng (an inland site in China) was impacted by marine aerosols; (d) photoreduction had a significant impact on fine-particle bound mercury during haze evolution and a relatively more intense solar radiation may be conducive to photoreduction during haze. These findings provide a theoretical basis for developing methods and strategies to control fine-particle bound mercury pollution.
Article
Total gaseous mercury (Hg) (TGM), gaseous oxidized Hg (GOM), and particulate-bound Hg (PBM) concentrations and dry depositions were measured at an urban site in central Taiwan. The concentrations were 6.14±3.91 ng m(-3), 332±153, and 71.1±46.1 pg m(-3), respectively. These results demonstrate high Hg pollution at the ground level in Taiwan. A back trajectory plot shows the sources of the high TGM concentration were in the low atmosphere (<500 m) and approximately 50% of the air masses coming from upper troposphere (>500 m) were associated with low TGM concentrations. This finding implies that Hg is trapped in the low atmosphere and comes from local Hg emission sources. The conditional probability function (CPF) reveals that the plumes of high TGM concentrations come from the south and northwest of the site. The plume from the south comes from two municipal solid waste incinerators (MSWIs). However, no significant Hg point source is located to the northwest of the site; therefore, the plumes from the northwest are hypothesized to be related to the combustion of agricultural waste. Dry deposition fluxes of Hg measured at this site considerably exceeded those measured in North America. Overall, this area is regarded as a highly Hg contaminated area because of local Hg emission sources.
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Wood smoke from forest fires or anthropogenic activities can be a significant contributor to regional haze and PM2.5, but routine methods to quantify the extent of this source's contribution to visibility impairment and ambient levels of PM2.5 have not been developed and evaluated. This paper evaluates an approach to semi-quantitatively measure the fraction of PM that is from wood smoke (WS PM) in real-time. A two-wavelength Aethalometer™ (Magee Scientific model AE42) was used to measure the optical absorption of PM-1 ambient aerosol at 880 nm (BC) and 370 nm (UV-C). Certain organic aerosol components of wood smoke PM have enhanced optical absorption at 370 relative to 880 nm ("Delta-C"). This enhanced absorption is shown to be a specific "indicator" of WS PM, but alone is not a quantitative mass measurement. Improved quantification of WS PM can be obtained when the two-channel Aethalometer is collocated with continuous PM2.5 and other measurements. A pilot study was performed to evaluate the potential for this approach in Rutland, VT between February and July, 2004. Aethalometer measurements were made at an existing VT-DEC monitoring site, collocated with continuous PM2.5, SO2, CO, and NOx measurements. Rutland is a valley city surrounded by elevated terrain and subject to strong winter morning inversions, and winter PM2.5 sample filters from this site often exhibit a distinct "wood smoke odor". Local mobile sources also contribute to the observed PM and BC concentrations (but not Delta-C) at this site, primarily during weekday morning rush hour periods. Monitoring was performed during seasons with and without wood smoke to allow assessment of mobile source signatures without heating sources, since both have large BC components. The UNMIX model was used to apportion measured PM2.5 into several source categories; NOx and SO2 are used to distinguish PM contributions from WS, oil burning (primarily space heating), and mobile sources. WS PM was associated only with the Aethalometer Delta-C measurement even in the presence of substantial local mobile source and oil-burning aerosols.
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Total airborne mercury (TAM) and carbon monoxide (CO) were measured in 22 pollution transport “events” at Mt. Bachelor Observatory (MBO), USA (2.8 km asl) between March 2004 and September 2005. Submicron particulate scattering (σsp), ozone (O3), and nitrogen oxides (NOy) were also measured and enhancement ratios for each chemical and aerosol species with CO were calculated. Events were categorized based on their source regions, which were determined by a combination of back trajectories, satellite fire detections, chemical and aerosol enhancement ratios, and meteorology. The mean ΔTAM/ΔCO values for each source region are: East Asian industrial (, n=10 events, 236 h), Pacific Northwest U.S. (PNW) biomass burning (, n=7 events, 173 h), and Alaska biomass burning (, n=3 events, 96 h). The ΔTAM/ΔCO means from Asian long-range transport (ALRT) and biomass burning events are combined with previous estimates of CO emissions from Chinese anthropogenic, global biomass burning, and global boreal biomass sources in order to estimate the emissions of gaseous elemental mercury (GEM) from these sources. The GEM emissions that we calculate here are: Chinese anthropogenic (), global biomass burning , and global boreal biomass burning , with errors estimated from propagating the uncertainty in the mean enhancement ratios and CO emissions. A comparison of our results with published mercury (Hg) emissions inventories reveals that the Chinese GEM emissions from this study are higher by about a factor of two, while our estimate for global biomass burning is consistent with previous studies.
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A source apportionment study was performed for particulate matter in the small village of Roveredo, Switzerland, where more than 70% of the households use wood burning for heating purposes. A two-lane trans-Alpine highway passes through the village and contributes to the total aerosol burden in the area. The village is located in a steep Alpine valley characterized by strong and persistent temperature inversions during winter, especially from December to February. During two winter and one early spring campaigns, a seven-wavelength aethalometer, high volume (HIVOL) samplers, an Aerodyne quadrupole aerosol mass spectrometer (AMS), an optical particle counter (OPC), and a Sunset Laboratory OCEC analyzer were deployed to study the contribution of wood burning and traffic aerosols to particulate matter. A linear regression model of the carbonaceous particulate mass in the submicrometer size range CM(PM1) as a function of aerosol light absorption properties measured by the aethalometer is introduced to estimate the particulate mass from wood burning and traffic (PM(wb), PM(traffic)). This model was calibrated with analyses from the 14C method using HIVOL filter measurements. These results indicate that light absorption exponents of 1.1 for traffic and 1.8-1.9 for wood burning calculated from the light absorption at 470 and 950 nanometers should be used to obtain agreement of the two methods regarding the relative wood burning and traffic emission contributions to CM(PM1) and also to black carbon. The resulting PM(wb) and PM(traffic) values explain 86% of the variance of the CM(PM1) and contribute, on average, 88 and 12% to CM(PM1), respectively. The black carbon is estimated to be 51% due to wood burning and 49% due to traffic emissions. The average organic carbon/total carbon (OC/TC) values were estimated to be 0.52 for traffic and 0.88 for wood burning particulate emissions.
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Previously it has been suggested that certain organic aerosol components of wood smoke have enhanced ultraviolet absorption at 370 nm relative to 880 nm in two-wavelength aethalometer measurements. This enhanced absorption could serve as an indicator of wood burning particles. Two-wavelength (370 nm and 880 nm) aethalometer measurements were made at urban sites in Rochester, New York and Laredo, Texas from August 1 to December 31, 2009 and from December 23, 2007 to January 2, 2008, respectively. In Rochester, Delta-C (UVBC(370 nm)- BC(880 nm)) values were higher by a factor of 3 during the night than during the day in November and December when residential wood burning was common. In Laredo, particularly high Delta-C values were observed on Christmas Eve and New Year's Eve and were attributed to biomass burning and firework emissions. Exponential decay was found to be a good estimator for predicting BC concentrations at different wind speeds regardless of wind directions.
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KCl-coated denuders have become a standard method for measurement of gaseous oxidized mercury, but their performance has not been exhaustively evaluated, especially in field conditions. In this study, KCl-coated and uncoated quartz denuders loaded with HgCl2 and HgBr2 lost 29–55% of these compounds, apparently as elemental mercury, when exposed to ozone (range of 6–100 ppb tested). This effect was also observed for denuders loaded with gaseous oxidized mercury at a field site in Nevada (3–37% of oxidized mercury lost). In addition, collection efficiency decreased by 12–30% for denuders exposed to 50 ppb ozone during collection of HgCl2. While data presented were obtained from laboratory tests and as such do not exactly simulate field sampling conditions, these results indicate that the KCl denuder GOM collection method may not be as robust as previously thought. This work highlights needs for further testing of this method, clear identification of gaseous oxidized mercury compounds in the atmosphere, and development of field calibration methods for these compounds.
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Accurate and reliable sampling and analysis of mercury forms is an overriding aim of any atmospheric monitoring effort which seeks to understand the fate and transport of the metal in the environment. Although a fraction of the total mercury forms found in the atmosphere, particulate phase mercury, Hg p , is believed to play a prominent role in both wet and dry deposition to the terrestrial and aquatic environments. Currently, microwave acid extraction and thermoreductive methodologies for analysis of Hg p samples are widely used. We report on the potential for the use of a thermoreductive method for Hg p analysis to evaluate and optimize it for use in routine monitoring networks. Pre-baked quartz filters can be placed in particulate samplers with well-characterized size cuts, such as dichotomous samplers and microoriface impactors. The thermoreductive methodology facilitates rapid analysis after sample collection. It requires no chemical extraction thereby eliminating the potential for contamination and generation of hazardous waste. Our results indicate that, on average, the thermoreductive method yields 30% lower values for fine fraction Hg p when compared with microwave acid digestion. This may be due to matrix interferents that reduce the collection efficiency of mercury onto gold preconcentration traps. Results for total particulate mercury samples indicate that on average the thermoreductive method yields 56% lower values for the coarse fraction when compared with microwave acid digestion.
Article
Continuous and semi-continuous measurements of organic carbon (OC), elemental carbon (EC) and PM 2:5 were performed during the summer of 2002 in Rochester, NY and Philadelphia, PA. During the study period in Philadelphia, high concentrations of wood smoke from a Canadian forest fire were transported to the monitoring site. Two-hour integrated thermal EC (EC)/optical EC ðBC S Þ using a Sunset Lab OC/EC analyzer and continuous Aethalometer optical EC ðBC A Þ using a two-wavelength Aethalometer were compared in various environments. The weekdays diurnal average for EC peaked during the morning rush-hour and was much higher than the value during weekends, whereas the OC results showed no diurnal variation of OC during either weekdays or weekends at both sites. The diurnal variations of BC A were also strongly correlated with the rush-hour traffic. The correlation coefficient between EC and BC A in Rochester ðr 2 ¼ 0:84Þ was higher than in Philadelphia ðr 2 ¼ 0:60Þ while the BC A /EC slopes were 3.3 and 2.7 in Rochester and Philadelphia, respectively. The difference in the slopes indicates that the specific attenuation cross-section used for the optical carbon analysis depends on the physical and chemical characteristics of elemental carbon. During the Canadian forest fire, the BC A /EC slope dramatically dropped to 0.4 with a correlation coefficient of 0.60. The decrease of the proportionality between EC and BC A demonstrates the variability of the absorption coefficient. The level of UV absorbing organic compounds significantly increased during the fire aerosol episode suggesting the presence of abundant organic compounds in the forest fire smoke particles.
Article
Field observations made at Harvard Forest [Petersham, MA, U.S.A. (42 degrees 54' N, 72 degrees 18' W)] during early July 2002 show clear evidence of long-range transport of gaseous mercury (Hg) in a smoke plume from a series of boreal forest fires in northern Quebec. These measurements indicated significant and highly correlated increases in Hg and CO during the plume event. The Hg:CO emissions ratio determined from the data (8.61 x 10(-8) mol mol(-1)) was combined with previously published information on CO emissions and biomass burned to determine a mean area-based Hg emission flux density for boreal forest fires (1.5 g Hg ha(-1)), annual Hg emissions from Canadian forest fires (3.5 tonnes), and annual global Hg emissions from boreal forest fires (22.5 tonnes). Annual Hg emissions from boreal fires in Canada may equal 30% of annual Canadian anthropogenic emissions in an average fire year and could be as high as 100% during years of intense burning. The Hg:CO emissions ratio of this study was much lower than those reported for a temperate forest in Ontario and a pine/shrub vegetation in South Africa, suggesting that fire emission is dependent on biome/species and that any extrapolation from a single fire event to determine the global fire emission is speculative.
Article
Atmospheric Hg is present in different physical and chemical forms, which determine its atmospheric transformation and transport capacities. The chemistry of Hg in flue gases is thus of importance for the deposition pattern around point source emissions. In order to apply Hg cleaning methods in flue gases its speciation is also of importance. To investigate this under realistic conditions, a 17 kW propane fired flue gas generator was used, while the kinetics of specific Hg reactions were investigated in a continuous flow reactor. Elemental Hg is readily oxidized by Cl2 and HCl both at room and at elevated temperatures (up to 900 °C) but not by NH3, N2O, SO2 or H2S. It reacts with O2 if a catalyst, such as activated carbon, is present. A slow reaction between Hg and NO2 has also been noted.
Article
An estimate of the global emission of mercury from anthropogenicsources in 1995 has been prepared. Major emphasis is placed onemissions from stationary combustion sources, non-ferrous metalproduction, pig iron and steel production, cement production andwaste disposal. About three quarters of the total emission,estimated to be about 1900 tonnes, was from combustion of fuels, particularly coal combustion in China, India, and South and NorthKorea. In general, the Asian countries contribute about 56% to the global emissions of mercury to the atmosphere. Europe and North America seem to contribute less than 25%. The major chemical form of mercury emitted to the atmosphere is gaseouselemental mercury, contributing with about 53% to the totalemissions, followed by gaseous bivalent mercury with 37%. The Hg emissions on particles contribute only about 10% to the total emissions. Again, Asia contributes about 50% to the totalemissions of all individual chemical forms of mercury.
Article
Detailed gaseous and particle emissions along with thermal efficiency measurements were made on three mid-sized high-efficiency wood boilers with thermal output capacities of 150 kW(514 000 Btu h�1) (n = 2) and 500 kW(1.7mmBtu h�1) (n=1). Wood chips and commercial wood pellets were used as fuel. Continuous emissions of CO,NOx, SO2, fine particle mass (PM2.5), and ultrafine particle number distributions were determined using a dilution tunnel sampling system. PM2.5 and semivolatile organic compound characterization was performed. Low concentrations of CO, organic carbon (OC), and elemental carbon (EC) during steady-state boiler operation indicated good combustion conditions. Fine particle mass from wood pellets was predominantly K+ and SO4 2-�, with <8% OC and <2% EC. Inorganic emissions (PM2.5, NOx, and SO2) were found to depend upon fuel quality, which indicates the need for wood pellet fuel standards in the U.S. Cd, Pb, Ti, Rb, and Zn were found to be enriched in PM2.5, which is of concern for human health. Levoglucosan was a predominant organic compound found for all fuels, ranging from 38 to 82 ìg/MJ. Total particle and semivolatile polycyclic aromatic hydrocarbon (PAH) emissions were relatively low (19.4�92.8 ìg/MJ). The thermal efficiencies of the wood pellet boilers determined using the provisional American Society of Heating, Refrigeration and Air Conditioning Engineers (ASHRAE) standard 155p ranged between 70 and 86% for the 150 kW boiler tested and between 75 and 91% for the 500 kW boiler. The use of ASHRAE 155p allowed for the determination of the linear relationship between the energy input and the energy output over the range of energy outputs rather than only determining the efficiency at minimum and full load as is the current standard practice. Boiler capacity had no significant effect on efficiency; however, the operating conditions, such as fuel feed rate, outlet water temperature, and building demand, did affect the results.
Article
Mercury emissions from forest fires in Europe and in North African countries bordering the Mediterranean Sea were estimated on the basis of ground-based forest fires data, forests phytomass and measured emission factors. Satellite observations were used to assess mercury emissions in Russian Federation through the assessment of spatial and temporal distributions of forest phytomass content and forest burnt areas. Annual mercury emissions in Europe were in the range of 0.9–3.6 Mg yr−1, Italy and Portugal have the highest emissions with an average of 821 and 459 kg yr−1 respectively, followed by Spain (394 kg yr−1), France (247 kg yr−1) and Poland (191 kg yr−1). On regional scale, Hg emissions from this particular source in the Mediterranean region is 2.3 Mg yr−1 (in the range 0.4–4.0 Mg yr−1) on average, while emissions from African and Middle East countries bordering the Mediterranean Sea are not significant. Mercury emissions in the Russian Federation are in the range of 3.4–24.8 Mg yr−1 (16 Mg yr−1 on average).
Article
The emission of mercury from biomass burning was investigated in laboratory experiments and the results confirmed in airborne measurements on a wildfire near Hearst, Ont. Mercury contained in vegetation (live, dead, coniferous, deciduous) was essentially completely released in laboratory burns in the form of gaseous elemental mercury and mercury contained in particles. Replicate burns of dry Ponderosa needles indicated a linear relationship between emitted mercury and fuel mass loss. Regionally collected fuels showed the same behavior as the replicate burns, i.e. essentially total removal of mercury. Mercury released from fuel could be accounted for as gaseous and particulate mercury in the smoke. The mercury content of regionally collected fuels varied between 14 and 70 ng/g on a dry mass (dm) basis.The smoke plume from a small wildfire was investigated with a research aircraft yielding a mean output of of elemental mercury for each ppm of CO2 emitted. The particulate mercury determined by sampling at specific points in the plume was compared to elemental mercury of 0.56 ng/m3 for the same air, supporting the conclusion that most of the mercury was emitted in the gaseous elemental form.Emission factors for the high/low mercury content samples of the laboratory burns were 14–71×10−6 and 112×10−6 g Hg/kg (dm) fuel for the wildfire. The difference is believed to be the contribution of mercury released from fire-heated soil. Mercury budgets extrapolated from this single wildfire gave upper emission limits of 66 t/yr for temperate/boreal forests. This large source estimate must be refined and included in future regional and global models. Forests are sinks for mercury already in the atmosphere, thus the wildfire “source” is part of the overall cycling of mercury originating from other sources.
Article
This paper presents a broad overview and synthesis of current knowledge and understanding pertaining to all major aspects of mercury in the atmosphere. The significant physical, chemical, and toxicological properties of this element and its environmentally relebant species encountered in the atmosphere are examined. Atmospheric pathways and processes considered herein include anthropogenic as well as natural sources of Hg emissions to the atmosphere, aerial transport and dispersion (including spatial and temporal variability), atmospheric transformations (both physical and chemical types), wet and dry removal/deposition processes to Earth's surface. In addition, inter-compartmental (air-water/soil/vegetation) transfer and biogeochemical cycling of mercury are considered and discussed. The section on numerical modelling deals with atmospheric transport models as well as process-oriented models. Important gaps in our current knowledge of mercury in the atmospheric environment are identified, and suggestions for future areas of research are offered.
Article
Semi-continuous measurements of ambient mercury (Hg) species were performed in Detroit, MI, USA for the calendar year 2003. The mean (±standard deviation) concentrations for gaseous elemental mercury (GEM), particulate mercury (HgP), and reactive gaseous mercury (RGM) were 2.2±1.3 ng m−3, 20.8±30.0, and 17.7±28.9 pg m−3, respectively. A clear seasonality in Hg speciation was observed with GEM and RGM concentrations significantly (p<0.001) greater in warm seasons, while HgP concentrations were greater in cold seasons. The three measured Hg species also exhibited clear diurnal trends which were particularly evident during the summer months. Higher RGM concentrations were observed during the day than at night. Hourly HgP and GEM concentrations exhibited a similar diurnal pattern with both being inversely correlated with RGM. Multivariate analysis coupled with conditional probability function analysis revealed the conditions associated with high Hg concentration episodes, and identified the inter-correlations between speciated Hg concentrations, three common urban air pollutants (sulfur dioxide, ozone, and nitric oxides), and meteorological parameters. This analysis suggests that both local and regional sources were major factors contributing to the observed temporal variations in Hg speciation. Boundary layer dynamics and the seasonal meteorological conditions, including temperature and moisture content, were also important factors affecting Hg variability.
Article
Eight types of agricultural and forest fuels including 4 cereal crop residues and 4 wood fuels were burned in a combustion wind tunnel to simulate the open burning of biomass. Concentrations for 19 PAH species in particulate matter were found to range between 120 and 4000 mg kg−1, representing between 1 and 70% of total PAH emission. Weakly flaming spreading fires in the cereals were observed to produce higher levels of heavier PAH than more robust fires, with greater partitioning of PAH to the particle phase. Individual species concentrations appeared well correlated within groups based primarily on molecular weight, but no single species was observed to correlate with all others to serve as an indicator of PAH emission strength. Equilibrium gas-particle partitioning did not appear to be achieved within the 3–5 s residence time prior to sampling for sampling temperatures between 32 and 87°C, and in particular for the heavier species emitted from wood fuel pile fires with higher stack gas temperatures and shorter residence times. Total PAH emission, particle-phase concentrations, and fraction of PAH on particles were more strongly influenced by burning conditions than by fuel type.
Article
In the United States, residential wood combustion (RWC) is responsible for 7.0% of the national primary PM(2.5) emissions. Exposure to RWC smoke represents a potential human health hazard. Organic components of wood smoke particles absorb light at 370 nm more effectively than 880 nm in two-wavelength aethalometer measurements. This enhanced absorption (Delta-C = BC(370 nm) - BC(880 nm)) can serve as an indicator of RWC particles. In this study, aethalometer Delta-C data along with measurements of molecular markers and potassium in PM(2.5) were used to identify the presence of airborne RWC particles in Rochester, NY. The aethalometer data were corrected for the loading effect. Delta-C was found to strongly correlate with wood smoke markers (levoglucosan and potassium) during the heating season. No statistically significant correlation was found between Delta-C and vehicle exhaust markers. The Delta-C values were substantially higher during winter compared to summer. The winter diurnal pattern showed an evening peak around 21:00 that was particularly enhanced on weekends. A relationship between Delta-C and PM(2.5) was found that permits the estimation of the contribution of RWC particles to the PM mass. RWC contributed 17.3% to the PM(2.5) concentration during the winter. Exponential decay was a good estimator for predicting Delta-C concentrations at different winter precipitation rates and different wind speeds. Delta-C was also sensitive to remote forest fire smoke.
Article
The impact of Canadian forest fires in Quebec on May 31, 2010 on PM(2.5), carbonaceous species, and atmospheric mercury species was observed at three rural sites in northern New York. The results were compared with previous studies during a 2002 Quebec forest fire episode. MODIS satellite images showed transport of forest fire smoke from southern Quebec, Canada to northern New York on May 31, 2010. Back-trajectories were consistent with this regional transport. During the forest fire event, as much as an 18-fold increase in PM(2.5) concentration was observed. The concentrations of episode-related OC, EC, BC, UVBC, and their difference (Delta-C), reactive gaseous mercury (RGM), and particle-bound mercury (PBM) were also significantly higher than those under normal conditions, suggesting a high impact of Canadian forest fire emissions on air quality in northern New York. PBM, RGM, and Delta-C are all emitted from forest fires. The correlation coefficient between Delta-C and other carbonaceous species may serve as an indicator of forest fire smoke. Given the marked changes in PBM, it may serve as a more useful tracer of forest fires over distances of several hundred kilometers relative to GEM. However, the Delta-C concentration changes are more readily measured.
Article
Continuous atmospheric measurements of speciated mercury (Hg) (elemental mercury (Hg⁰), reactive gaseous mercury (RGM), and particulate mercury (Hgp)) were made in Rochester, NY from Dec 2007 to May 2009. Continuous measurements of ozone (O₃), sulfur dioxide (SO₂), carbonmonoxide (CO), particulate matter (PM₂.₅), and meteorological data were also available. A principle components analysis (PCA) of 3886 observations of 13 variables for the period identified six major factors. Melting snow was observed to be a source of Hg⁰in winters. Positive correlations between RGM and O₃ in the spring and summer may be indicative of Hg⁰ oxidation. RGM concentrations increased simultaneously with SO₂ suggesting the influence of coal fired power plants (CFPP). The fifth factor (F5) containing O₃ (high negative loading), CO (positive loading), Hg⁰ and Hg(p) (positive), and/or RGM (negative) was identified as a mobile source which was usually observed during morning rush hours (6:00-9:00 a.m.). The concentrations of the three mercury species from the direction of the CFPP were significantly reduced following the shutdown of this source.
Article
The average global annual mercury emission estimate from biomass burning (BMB) for 1997-2006 is 675 +/- 240 Mg/year. This is equivalentto 8% of all currently known anthropogenic and natural mercury emissions. By season, the largest global emissions occur in August and September, the lowest during northern winters. The interannual variability is large and region-specific, and responds to drought conditions. During this particular time period, the largest mercury emissions are from tropical and boreal Asia, followed by Africa and South America. They do not coincide with the largest carbon biomass burning emissions, which originate from Africa. Frequently burning grasslands in Africa and Australia, and agricultural waste burning globally, contribute relatively little to the mercury budget The released mercury from BMB is eventually deposited locally and globally and contributes to the formation of toxic bioaccumulating methyl mercury. Furthermore, increasing temperature in boreal regions, where the largest soil mercury pools reside, is expected to exacerbate mercury emission because of more frequent larger, and more intense fires.
Article
Global Hg emissions are presented for the year 2050 under a variety of assumptions about socioeconomic and technology development. We find it likely that Hg emissions will increase in the future. The range of 2050 global Hg emissions is projected to be 2390-4860 Mg, compared to 2006 levels of 2480 Mg, reflecting a change of -4% to +96%. The main driving force for increased emissions is the expansion of coal-fired electricity generation in the developing world, particularly Asia. Our ability to arrest the growth in Hg emissions is limited by the relatively low Hg removal efficiency of the current generation of emission control technologies for coal-fired power plants (flue-gas desulfurization). Large-scale deployment of advanced Hg sorbent technologies, such as Activated Carbon Injection, offers the promise of lowering the 2050 emissions range to 1670-3480 Mg, but these technologies are not yet in commercial use. The share of elemental Hg in total emissions will decline from today's levels of approximately 65% to approximately 50-55% by 2050, while the share of divalent Hg will increase. This signals a shift from long-range transport of elemental Hg to local deposition of Hg compounds-though emissions of both species could increase under the worst case.
Article
First-stage mercury oxidation reactions typical of coal combustion flue gases were investigated. The present study is a determination of the kinetic and thermodynamic parameters of the bimolecular reactions, Hg + Cl(2) <--> HgCl + Cl, Hg + HCl <--> HgCl + H, and Hg + HOCl <--> HgCl + OH, at the B3LYP/RCEP60 VDZ level of theory over a temperature range of 298.15 to 2000 K at atmospheric pressure. Conventional transition state theory was used to predict the forward and reverse rate constants for each reaction and ab initio based equilibrium constant expressions were calculated as a function of temperature. Reasonable agreement was achieved between the calculated equilibrium constants and the available experimental values.
Article
Hourly averaged gaseous elemental Hg (GEM) concentrations and hourly integrated reactive gaseous Hg (RGM), and particulate Hg (Hg(p)) concentrations in the ambient air were measured at Huntington Forest in the Adirondacks, New York from June 2006 to May 2007. The average concentrations of GEM, RGM, and Hg(p) were 1.4 +/- 0.4 ng m(-3), 1.8 +/- 2.2 pg m(-3), and 3.2 +/- 3.7 pg m(-3), respectively. RGM represents < 3.5% of total atmospheric Hg or total gaseous Hg (TGM: GEM + RGM) and Hg(p) represents < 3.0% of the total atmospheric Hg. The highest mean concentrations of GEM, RGM, and Hg(p) were measured during winter and summer whereas the lowest mean concentrations were measured during spring and fall. Significant diurnal patterns were apparent in warm seasons for all species whereas diurnal patterns were weak in cold seasons. RGM was better correlated with ozone concentration and temperature in both warm (rho (RGM - ozone) = 0.57, p < 0.001; rho (RGM - temperature) = 0.62, p < 0.001) and cold seasons (rho (RGM - ozone) = 0.48, p = 0.002; rho (RGM - temperature) = 0.54, p = 0.011) than the other species. Potential source contribution function (PSCF) analysis was applied to identify possible Hg sources. This method identified areas in Pennsylvania, West Virginia, Ohio, Kentucky, Texas, Indiana, and Missouri, which coincided well with sources reported in a 2002 U.S. mercury emissions inventory.
Article
Atmospheric mercury is predominantly present in the gaseous elemental form (Hg0). However, anthropogenic emissions (e.g., incineration, fossil fuel combustion) emit and natural processes create particulate-phase mercury(Hg(p)) and divalent reactive gas-phase mercury (RGM). RGM species (e.g., HgCl2, HgBr2) are water-soluble and have much shorter residence times in the atmosphere than Hg0 due to their higher removal rates through wet and dry deposition mechanisms. Manual and automated annular denuder methodologies, to provide high-resolution (1-2 h) ambient RGM measurements, were developed and evaluated. Following collection of RGM onto KCl-coated quartz annular denuders, RGM was thermally decomposed and quantified as Hg0. Laboratory and field evaluations of the denuders found the RGM collection efficiency to be >94% and mean collocated precision to be <15%. Method detection limits for sampling durations ranging from 1 to 12 h were 6.2-0.5 pg m(-3), respectively. As part of this research, the authors observed that methods to measure Hg(p) had a significant positive artifact when RGM coexists with Hg(p). This artifact was eliminated if a KCl-coated annular denuder preceded the filter. This new atmospheric mercury speciation methodology has dramatically enhanced our ability to investigate the mechanisms of transformation and deposition of mercury in the atmosphere.
Article
Mercury (Hg) concentration, reservoir mass, and Hg reservoir size were determined for vegetation components, litter, and mineral soil for two Sierran forest sites and one desert sagebrush steppe site. Mercury was found to be held primarily in the mineral soil (maximum depth of 60 to 100 cm), which contained more than 90% of the total ecosystem reservoir. However, Hg in foliage, bark, and litter plays a more dominant role in Hg cycling than the mineral soil. Mercury partitioning into ecosystem components at the Sierran forest sites was similar to that observed for other US forest sites. Vegetation and litter Hg reservoirs were significantly smaller in the sagebrush steppe system because of lower biomass. Data collected from these ecosystems after wildfire and prescribed burns showed a significant decrease in the Hg pool from certain reservoirs. No loss from mineral soil was observed for the study areas but data from fire severity points suggested that Hg in the upper few millimeters of surface soil may be volatilized due to exposure to elevated temperatures. Comparison of data from burned and unburned plots suggested that the only significant source of atmospheric Hg from the prescribed burn was combustion of litter. Differences in unburned versus burned Hg reservoirs at the forest wildfire site demonstrated that drastic reduction in the litter and above ground live biomass Hg reservoirs after burning had occurred. Sagebrush and litter were absent in the burned plots after a wildfire suggesting that both reservoirs were released during the fire. Mercury emissions due to fire from the forest prescribed burn, forest wildfire, and sagebrush steppe wildfire sites were roughly estimated at 2.0 to 5.1, 2.2 to 4.9, and 0.36+/-0.13 g ha(-1), respectively, with litter and vegetation being the most important sources.
Article
Recent studies have shown that emissions of mercury (Hg), a hazardous air pollutant, from fires can be significant. However, to date, these emissions have not been well-quantified for the entire United States. Daily emissions of Hg from fires in the lower 48 states of the United States (LOWER48) and in Alaska were estimated for 2002-2006 using a simple fire emissions model. Emission factors of Hg from fires in different ecosystems were compiled from published plume studies and from soil-based assessments. Annual averaged emissions of Hg from fires in the LOWER48 and Alaska were 44 (20-65) metric tons yr(-1), equivalent to approximately 30% of the U.S. EPA 2002 National Emissions Inventory for Hg. Alaska had the highest averaged monthly emissions of all states; however, the emissions have a high temporal variability. Emissions from forests dominate the inventory, suggesting that Hg emissions from agricultural fires are not significant on an annual basis. The uncertainty in the Hg emission factors due to limited data leads to an uncertainty in the emission estimates on the order of +/-50%. Research is still needed to better constrain Hg emission factors from fires, particularly in the eastern U.S. and for ecosystems other than forests.
Evaluation of a New Approach for Real Time Assessment of Wood Smoke PM Visibility Specialty Conference on Regional and Global Perspectives on Haze: Causes, Consequences and Controversies Atmospheric mercury (Hg) in the Adirondacks: concentrations and Sources
  • G Allen
  • P Babich
  • R Poirot
  • H.-D Choi
  • T M Holsen
  • P K Hopke
Allen, G., Babich, P., Poirot, R., 2004. Evaluation of a New Approach for Real Time Assessment of Wood Smoke PM. J. AIR WASTE MANAGE, Visibility Specialty Conference on Regional and Global Perspectives on Haze: Causes, Consequences and Controversies, Asheville, NC. Choi, H.-D., Holsen, T.M., Hopke, P.K., 2008. Atmospheric mercury (Hg) in the Adirondacks: concentrations and Sources. Environ. Sci. Technol. 42, 5644–5653.
Mercury Study Report to Congress
USEPA, 1997. Mercury Study Report to Congress, Office of Air Quality Planning and Standards and Office of Research and Development.