Dry Deposition Samples Research Articles

Wet and dry deposition fluxes of mercury in Japan

Wet and dry deposition fluxes of mercury were measured concurrently from December 2002 to November 2003 at 10 sites in Japan (nine sites for dry deposition measurements). Precipitation and dry deposition (gases and particles) were collected every half-month using an automatic wet and dry deposition sampler. This sampler is composed of a precipitation sampler and a water surface sampler for dry deposition. The results showed that wet deposition fluxes of mercury increase generally during summer when the precipitation amount increases. In contrast, the seasonal variations of the dry deposition fluxes were very small compared to those of the wet deposition fluxes. It was found that wet deposition plays a dominant role in mercury deposition in Japan, contributing fluxes ranging from 0.99 to 2.2 times (1.6 times on average at nine sites) those of the dry deposition fluxes. There was a high correlation between the annual wet deposition flux of mercury and annual precipitation amount (r2=0.73, P<0.01). Thus, about 70% of the variance of mercury wet deposition in Japan is explained by precipitation amount. This is probably because mercury wet deposition is dominated by the scavenging of reactive gaseous mercury (RGM) by precipitation via oxidation of gaseous elemental mercury (Hg0) in the gas and aqueous phases. In addition, a similar relationship between the annual wet deposition flux and precipitation amount (r2=0.55, P<0.001) was observed at the Mercury Deposition Network (MDN) sites in North America, suggesting that about 55% of the variance of mercury wet deposition is due to precipitation amount.

Atmospheric Dry Deposition to Marble and Red Stone

This paper presents dry deposition flux and deposition velocity of atmospheric particles on white marble and red stone at Dayalbagh, a suburban site of semi arid region, which is 10 km away from the industrial sector of the Agra city where due to agricultural practices vegetation predominates. The wind speed at Agra is mostly in the range of 1–2 m s−1. The atmospheric calm conditions at Agra in summer, monsoon, and winter seasons are 47%, 35%, and 76%, respectively. Industrial areas of the city are away from Dayalbagh and are located in the NE, E, SE, and SW sectors. The main industrial activities, which are in operation in Agra city and its outskirts, are foundry and forging industry. The other industrial activities in Agra are rubber processing, lime oxidation and pulverization, chemicals, engineering and brick refractory kilns. Dry deposition samples were collected on dry days on white marble and red stone (0.224 m × 0.224 m × 0.02 m) using surface washing method. Both slabs were fixed to an iron stand (1.5 m height) at an angle of about 80∘ from the horizontal and exposed for 24 h on the roof of the faculty building. The order of deposition flux on white marble is NH4+ > Mg2+ > Ca2+ > Na+ > Cl− > K+ > NO3− > SO42− > F− and that on red stone is NH4+ > Mg2+ > Ca2+ > SO42− > Na+ > NO3− > K+ > F− > Cl−. Average dry deposition flux of major ions varies from 3.4 to 128.5 μM m−2 d−1. The sum of major cations on white marble and red stone are 516.4 and 450.4 μ eq m−2 d−1, respectively while sum of major anions are 425.3 and 400.4 μ eq m−2 d−1 on white marble and red stone, respectively. Higher deposition of all ions was observed when wind blows from NE as most of the Agra Iron foundries and Ferozabad glass industries lie in this direction. The mean values of dry deposition velocity of ions vary between 0.22 cm s−1 to 1.49 cm s−1. Deposition velocity for all ions is higher on white marble than red stone inspite of rougher surface of red stone as compared to white marble. This could be due to the chemical nature of white marble, which is made of dolomite and hence adds significant amount of ions by dissolution during washing. Seasonally the deposition velocity was highest in winter.

An Adsorption-Separation Process for Collecting and Analyzing Atmospheric Mercury Deposits—Development of a Chelex 100 Resin Column System

Many previous studies for detecting the atmospheric mercury from wet deposition have been reported. In comparison, little effort has been made in studying mercury from dry deposition. There is currently no sampler that collects atmospheric mercury dry deposits. A new mercury dry deposition sampler has been designed conceptually. It employs a moving sheet of water to passively collect dry deposits of mercury. The water will be drained into a reservoir and recirculated through a resin column that is capable of retaining the mercury deposits. In this article, an adsorption-separation process is proposed for collecting and analyzing dry atmospheric mercury deposits through development of a Chelex 100 resin column system. When the water flows continually through the resin column, the mercury deposits will be adsorbed by the resin. After the sampling process, the mercury can then be separated from the resin through application of an acidic solution. The extracted solution that contains the separated mercury is then analyzed through a cold-vapor mercury analyzer. In this study, hydrochloric acid, nitric acid and sulfuric acid were tested. Chelex 100 resin (Sigma Chemical Co., St. Louis) selected for this study was tested under laboratory conditions using solutions of known mercury concentration in order to determine its efficiency in adsorption and separation. The results indicate that Chelex 100 resin could adsorb more than 95% of the mercury in the test solutions with a pH range from 1.65 to 11.45. Sulfuric acid was found to have better overall performance than hydrochloric acid and nitric acid in extracting (desorbing) the mercury from the resin column. The highest desorption rate (95.2%) was achieved with 4 N H2SO4 for a mercury solution of pH 5.90. Development of the adsorption-separation process and identification of the optimal system conditions provides scientific bases for designing the sampler. The experimental results are also useful for other mercury-related studies.

The impact of volcanic gases from Miyake island on the chemical constituents in precipitation in the Tokyo metropolitan area

The volcano on Miyake Island first erupted in July 2000 and continuous emission of volcanic gas from the collapsed caldera has been observed from the middle of August 2000. The large volcanic emission of SO 2 had a strong influence on Tokyo metropolitan area, which is located approximately 150 km north of Miyake Island. We measured major ions in precipitation and dry deposition samples which had been collected at five sampling sites (Yokohama, Kashiwa, Fujisawa, Yokosuka, and Hachioji) in the Tokyo metropolitan area for 12 years since 1990. We have evaluated quantitatively the impact of the volcanic SO 2 gas emitted from Miyake Island on the Tokyo metropolitan area by comparing depositional ionic constituents in the volcanic degassing period (from September 2000 to August 2001) with those in the normal period of the past 10 years (September 1990 to August 2000). nss-SO 4 2− concentrations in precipitation at the sampling sites in the Tokyo metropolitan area were 59.5–77.0 μeq/L during the degassing period, and 33.3–44.1 μeq/L during the normal period, respectively. The difference of nss-SO 4 2− concentrations between the two periods was statistically significant. In contrast, no significant differences were observed in the concentrations of the other major ions (NH 4 +, nss-Ca 2+, Cl −, and NO 3 −) between the two periods. The impact of volcanic degassing from Miyake Island on the ionic concentrations in the precipitation of the Tokyo metropolitan area was seen only in the H + and nss-SO 4 2− concentrations. The annual wet deposition amount of volcanic nss-SO 4 2− into the Tokyo metropolitan area has been quantitatively estimated. The annual wet deposition amounts were calculated as 701±277 Meq/year (22.4±8.9 kt SO 2/year) on the total area of the Tokyo metropolitan area (14,000 km 2). The wet deposition amount of nss-SO 4 2− corresponds to only 0.15% of the total annual amount of volcanic SO 2 (15 Mt/year) emitted from Miyake Island from September 2000 to August 2001. This estimation is consistent with a previous study which reported that 0.3% of the atmospheric discharge of SO 2 from the volcano in Mt. Etna in Sicily was deposited by precipitation to the surrounding area (1200 km 2). The annual wet deposition amount of volcanic SO 2 to the Tokyo metropolitan area was at the same order of the magnitude (37±15%) as the annual anthropogenic SO 2 amount (60 kt/year) emitted from the Tokyo metropolitan area.

Wet and dry deposition patterns of plutonium in Daejeon, Korea

Plutonium in wet and dry deposition samples collected monthly at the Korea Institute of Nuclear Safety (KINS), Daejeon, Korea was determined during the period from January 2000 to August 2000. Monthly 239,240Pu deposition in Korea showed a maximum in the spring season (March to May), which was several times greater than that in Japan and corresponds to a seasonal cycle of soil dust fallout originating from the East Asian arid areas. The trajectory analysis of dust storms suggests that 239,240Pu deposition in Korea in spring is originating from plutonium-bearing surface soil particles from the East Asian arid areas. A significant part of the 239,240Pu deposition in spring in Korea is attributable to dry deposition.

Quantifying the dry deposition of ammonia in ammonia-rich and ammonia-poor environments using a surrogate surface approach

In this study, dry deposition samples were collected with both an aerodynamically smooth water surface (WSS) and a knife-edge surrogate surface (KSS) in Potsdam, NY, Solomons, MD, and at a farm in upstate NY intermittently between March 2000 and August 2001. The WSS and the citric acid-coated paper filter on the KSS were used to measure total ammonium deposition (NH 3 and p-NH 4 + ), while a greased Mylar disk on the KSS was used to measure particulate NH 4 + (p-NH 4 + ) deposition. An annular denuder system (ADS) was used to measure NH 3 gas phase and particulate NH 4 + concentrations. In side-by-side experiments with two WSSs, no statistical difference was found between simultaneously measured total ammonium deposition at any of the sites. Average total NH 3 fluxes measured with the WSS in Potsdam, Solomons, and at the farm were 3.1, 2.1, and 310 mg NH 4 + m −2 day −1 , respectively. Similarly gaseous NH 3 fluxes measured with the citric acid-coated paper on the KSS were 3.6, 2.1, and 500 mg NH 4 + m −2 day −1 , respectively. The p-NH 4 + fluxes to the KSS-greased strip were negligible at all three locations. Fluxes measured by the citric acid paper filters were slightly greater than those measured with the WSS suggesting that the acidic dry surfaces had a higher affinity for ammonia than the water in the WSS. The average gas-phase ammonia concentrations in Potsdam, Solomons, MD and at the farm were 0.60×10 −3 , 2.1×10 −3 , and 0.25 mg NH 4 + m −3 , respectively. The average ammonium concentrations were 0.50×10 −3 , 1.2×10 −3 , and 14×10 −3 mg NH 4 + m −3 , respectively.

Assessment of the potential for soil acidification in North India using the critical load approach and locally derived data for acidic and basic inputs

Major ions (Cl −, NO 3 −, SO 4 2−, Ca 2+, Mg 2+, Na +, K + and NH 4 +) were analysed in wet and dry deposition samples collected for 2 years using a polyethylene bottle and funnel collector at Agra in India. The deposition of ionic components (Ca 2+ and Mg 2+) derived from natural sources i.e. soil were higher than those of anthropogenic origin. In rainwater samples, non-sea-salt fraction was found to be 60–90%. In both wet and dry deposition Ca 2+ was found to be the dominant ion which may be due to its large particle diameter. Results suggest that most of the acidity, which occurs due to NO 3 −, SO 4 2− and Cl − is neutralized by alkaline constituents, which originate from airborne local soil and dust transported from the Thar desert. Acid neutralizing capacity of soil has also been quantified and found to be 33 × 10 3 neq g −1. Using deposition data, the critical load for acidity of soil with respect to Ashoka and Eucalyptus was evaluated. The present level of deposition of S and N was found to be much lower than critical loads calculated for S and N. Critical load of exceedance in terms of deposition acidity was also calculated and found to be negative. This indicates that with respect to these species, the ecosystem is protected at the current level of deposition.

Analysis of the Saharan dust regional transport

The Balkan Peninsula is situated in the impact zone of Saharan dust storms. The case of Saharan dust transport to Belgrade in the period of 14–17 April 1994 is analyzed using the Eta model for synoptic and meso scale processes. Air back trajectories are calculated at six model levels from 434 up to 5129 m with horizontal grid resolutions of 1°×1° and 10′×10′. Following cyclonic circulation the dust was picked up from North Africa, and transported over Mediterranean. Simultaneously, according to the analysis of the three lowest trajectories, transport of trace metals from Macedonia and southern Serbia by the Koshava wind might be dominant in the observed episode. Turbulent flow enhanced the coagulation process of initially clean dust particles with particles containing Pb and Cd. The coagulation and scavenging processes below and in clouds increased deposition rates of Pb and Cd in Belgrade in the course of wet removal, and consequently trough resuspension processes. Dry deposition samples contained characteristic particles up to 30 µm in diameter with Fe content of 11 to 15 atomic% and significant ratio Si/Fe of 3 to 5, determined for selected single particles by the SEM/EDX method. Following dry and wet deposition of Cd and Pb, a residual effect of dustfall is noticed throughout the vegetational period.

Occurence and Distribution of Polycyclic Aromatic Hydrocarbons in Ankara Precipitation

Urban atmospheric environment contains many trace organic pollutants that are related to the incomplete fuel combustion in domestic heating, industrial plants and automobile traffic. Removal of these pollutants from the atmosphere takes place through wet and dry deposition as well as chemical transformations. In this study, concentrations of polycyclic aromatic hydrocarbons (PAHs) in wet deposition samples were determined at an urban site of Turkey. Wet and dry deposition samples were collected using Andersen Rain Sampler. The sampler was modified accordingly for the collection of organic pollutants. Collected samples were preconcentrated by using solid phase extraction (SPE) disks and consecutively analyzed by Gas Chromatography-Mass Spectrometry (GC-MS). Among the 13 compounds quantified in this study, anthracene, fluoranthene, and pyrene were found more frequently and at elevated concentrations (202, 271 and 260 ng L-1 mean concentrations, respectively).Concentrations of PAHs were found to be high in winter period.

Precision of atmospheric dry deposition data from the Clean Air Status and Trends Network

A collocated, dry deposition sampling program was begun in January 1987 by the US Environmental Protection Agency to provide ongoing estimates of the overall precision of dry deposition and supporting data entering the Clean Air Status and Trends Network (CASTNet) archive. Duplicate sets of dry deposition sampling instruments were installed adjacent to existing instruments and have been operated for various periods at 11 collocated field sites. All sampling and operations were performed using standard CASTNet procedures. The current study documents the bias-corrected precision of CASTNet data based on collocated measurements made at paired sampling sites representative of sites across the network. These precision estimates include the variability for all operations from sampling to data storage in the archive. Precision estimates are provided for hourly, instrumental ozone (O 3) concentration and meteorological measurements, hourly model estimates of deposition velocity ( V d) from collocated measurements of model inputs, hourly O 3 deposition estimates, weekly filter pack determinations of selected atmospheric chemical species, and weekly estimates of V d and deposition for each monitored filter pack chemical species and O 3. Estimates of variability of weekly pollutant concentrations, expressed as coefficients of variation, depend on chemical species: NO 3 −∼8.1%; HNO 3∼6.4%; SO 2∼4.3%; NH 4 +∼3.7%; SO 4 2−∼2.3%; and O 3∼1.3%. Precision of estimates of weekly V d from collocated measurements of model inputs also depends on the chemical species: aerosols ∼2.8%; HNO 3∼2.6%; SO 2∼3.0%; and O 3∼2.0%. Corresponding precision of weekly deposition estimates are: NO 3 −∼8.6%; HNO 3 −∼5.2%; SO 2∼5.6%; NH 4 +∼3.9%; SO 4 2−∼3.5%; and O 3∼3.3%. Precision of weekly concentration, V d estimates, and deposition estimates are comparable in magnitude and slightly smaller than the corresponding hourly values. Annual precision estimates, although uncertain due to their small sample size in the current study, are consistent with the corresponding weekly values.

Atmospheric deposition of major ions and trace metals near an industrial area, Jordan.

Al, Cd, Cr, Cu, Fe, Mn, Pb, Zn, NH4+, Mg2+, Ca2+, Na+, K+, Cl-, NO3- and SO4(2-), along with pH were determined in wet and dry deposition samples collected at Al-Hashimya, Jordan. Mean trace metal concentrations were similar or less than those reported for other urban regions worldwide, while concentrations of Ca2+ and SO4(2-) were the highest. The high Ca2+ concentrations were attributed to the calcareous nature of the local soil and to the influence of the Saharan dust, while the high concentrations of SO4(2-) were attributed to the influence of anthropogenic sources and Saharan dust soil. Except for SO4(2-), NO3-, and Ca2+, dry deposition fluxes of measured metals and ions were higher than their corresponding wet deposition fluxes. The high annual average pH values recorded for wet and dry deposition samples were attributed to the neutralization of acidity by alkaline species. Cd, Cr, Cu, Pb, Zn, NO3- and SO4(2-) were enriched in wet and dry deposition samples relative to crustal material, and a significant anthropogenic contribution to these elements and ions is tentatively suggested. Finally, the possible sources and the main factors affecting the concentrations of the measured species are discussed.

Ambient concentrations and dry deposition fluxes of trace elements in Izmir, Turkey

Dry deposition samples were collected using a smooth surrogate surface at the Kaynaklar Campus of the Dokuz Eylul University in Izmir, Turkey. Concurrently ambient aerosol samples were collected. All samples were analyzed for anthropogenic and crustal trace elements. The average trace element concentrations and fluxes measured in this study were generally higher than those reported previously for urban and rural areas. The contribution of local terrestrial and anthropogenic sources were also investigated using enrichment factors (EFs) calculated relative to the local soil. Relatively lower EFs for ambient samples and high ambient concentrations indicated that the local soil was polluted and contributed significantly to ambient trace element concentrations. Deposition samples had higher EFs than the air samples. The EF sequences of trace elements were also different for deposition and ambient samples, probably due to the fact they have different mass median diameters and deposition velocities. The overall dry deposition velocities for trace elements calculated by dividing the particulate fluxes measured with the surrogate surfaces by ambient concentrations ranged from 0.6 (Al) to 6.2 cm s −1 (Fe). The agreement between the experimental dry deposition velocities determined in this study and the previously reported ones using similar techniques for trace elements was good.

Characterisation of particulate matter in the Royal Museum of Fine Arts, Antwerp, Belgium

Aerosol samples were collected during two campaigns in February and July 1999 both inside and outside the Koninklijk Museum voor Schone Kunsten (KMSK, Royal Museum of Fine Arts) in Antwerp. Bulk aerosol concentrations, as well as the composition of the individual particles, were determined. The influence of the outdoor aerosol was clearly visible. In winter, restoration and construction works constituted an additional indoor source of Ca-rich and Ca–Si particles. Along with sea salt, these were the main particle types identified in this season. In summer, S-rich particles were most frequent. The summer abundances of Ca-rich particles remained low, even though the museum is situated in a limestone building. Moreover, dry deposition samples were collected in order to determine what amount of particles could actually be deposited onto the works of art.

Measurements of major ion concentration in settled coarse particles and aerosols at a semiarid rural site in India

Deposition rates and deposition velocities of water-soluble ions (F, Cl, NO 3, SO 4, NH 4, Ca, Mg, Na and K) were measured at a rural site (Gopalpura, Agra). Dry deposition samples were collected throughout the year from December 1995 to August 1997, while the aerosol samples were collected only during the winter season of 1996. Surrogate technique was used to collect the dry deposition samples, while aerosol samples were collected on PTFE membrane filter. Deposition velocities ( V d) of SO 4 and NO 3 are ≤0.01 m s −1, while Ca, Mg, Na, K, NH 4, F and Cl exhibit greater than 0.01 m s −1. Equivalent concentration ratios of K/Na, Ca/Na and Mg/Na conform with the corresponding ratios of local soil, indicating the dominant contribution of local sources. Deposition rates are maximum in winter, followed by summer and monsoon. No significant differences are found in dry deposition rates of all ions or in atmospheric concentrations of soil-derived elements with respect to wind direction. However, in aerosols, concentrations of F, Cl, NO 3 and SO 4 are higher with winds from southwesterly and westerly directions corresponding to pollution sources located in these directions. Deposition data have been used to calculate the critical load of S and N for soil with respect to Triticum vulgaris. The critical load of actual acidity was found to be 622.4 eq ha −1 year −1 within the range of 500–1000 eq ha −1 year −1 as assessed by the RAINS-Asia model for this region. The present load of S and N (77.4 and 86.4 eq ha −1 year −1) was much lower than the critical load of S and N (622.4 and 2000 eq ha −1 year −1), indicating that at present there is no harmful effect on ecosystem structure and function.

Solid Phase Extraction for Determination of Polycyclic Aromatic Hydrocarbons from Atmospheric Wet and Dry Deposition Samples

Solid phase extraction with C-18 sorbent tubes was employed for extraction and preconcentration of trace level (ng/l) of polycyclic aromatic hydrocarbons (PAHs) from water samples obtained by collecting wet and dry atmospheric deposition. Recoveries of spiked PAHs from 0.2 to 10.0 l water samples ranged from 60% to 90%. Five deuterated PAHs (naphthalene- d 8 , acenaphthene- d 10 , anthracene- d 10 , chrysene- d 12 , and perylene- d 12 ) were added to the samples as surrogates. The recoveries of surrogates were in the same range as the spiked PAHs. The recoveries of surrogates were used to estimate the recoveries of ambient PAHs with a similar ring structure. Factors that contributed to the relatively low recoveries include breakthrough of the sorbates, adsorption on the container surface, and degradation in water during storage.

Atmospheric movements of lindane (gamma-hexachlorocyclohexane) from canola fields planted with treated seed.

Lindane (gamma-hexachlorocyclohexane [gamma-HCH]) is used as an insecticide in many countries. Concentrations of gamma-HCH have been found in air, water, soil, snow, and tissue samples throughout the world and concerns have been raised for its potential effects on human and ecosystem health. In Canada, gamma-HCH is primarily used as a treatment on canola (Brassica napus L) seed with an estimated 455.3 Mg applied in 1997 and 510.4 Mg in 1998. The purpose of this study was to measure gamma-HCH volatilization from fields planted with treated canola seed. Atmospheric dry and wet deposition and soil samples were collected for two growing seasons (1997 and 1998) from a canola field planted with treated seed. Atmospheric concentrations as high as 16.1 and 7.4 ng m(-3) were measured at 1 m above the canola field compared with maximum concentrations of 2.9 and 2.7 ng m(-3) measured above a grass field located 2 km away (1997 and 1998, respectively). On the basis of measurements made in this study it was estimated that between 12 and 30% of the gamma-HCH applied as canola seed treatment may volatilize and be released to the atmosphere. This would create an atmospheric loading of 66.4 to 188.8 Mg for the 6-wk period following planting, estimated from the quantity of seed sown on the Canadian prairies in 1998. Dry deposition rates and rain concentrations as high as 2,203 ng m(-2) d(-1) and 170 ng L(-1) were measured adjacent to the canola field.

Long Term Trend of Chemical Constituents in Tokyo Metropolitan Area in Japan

In recent years, acid rain has been a social problem all over the world. In Japan, it is also a big problem especially in the metropolitan area. Then, we have measured major ions such as H+, Na+, K+, Mg2+, Ca2+, Cl-, and in precipitation and dry deposition samples which had been collected at 9 sampling sites at Hiyoshi, Mita, Kashiwa, Shiki, Fujisawa, Yokosuka, Mitaka, Hachiouji, and Ashikaga in Tokyo Metropolitan area for 10 years since 1990. The average pH of precipitation in their sites was 4.56 (n=1906). As the results of multiple regression analysis showed that pH of precipitation was determined by 5 ions such as, nssCa2+(non sea salt calcium), nssCl(non sea salt chloride), (non sea salt sulfate) in the most of the sampling sites. Therefore, it is very important to investigate the behavior of these ions to understand the acidification of rain in Tokyo Metropolitan area. In this study, a long term trend of each ion concentration in precipitation and wet deposition was also investigated the base on the data we had observed at 7 sites for 10 years by the statistical method.

Overall elemental dry deposition velocities measured around Lake Michigan

Overall dry deposition velocities of several elements were determined by dividing measured fluxes by measured airborne concentrations in different particle size ranges. The dry deposition measurements were made with a smooth surrogate surface on an automated dry deposition sampler (Eagle II) and the ambient particle concentrations were measured with a dichotomous sampler. These long-term measurements were made in Chicago, IL, South Haven, MI, and Sleeping Bear Dunes, MI, from December 1993 through October 1995 as part of the Lake Michigan Mass Balance Study. In general, the dry deposition fluxes of elements were highly correlated with coarse particle concentrations, slightly less well correlated with total particle concentrations, and least well correlated with fine particle concentrations. The calculated overall dry deposition velocities obtained using coarse particle concentrations varied from approximately 12 cm s −1 for Mg in Chicago to 0.2 cm s −1 for some primarily anthropogenic metals at the more remote sites. The velocities calculated using total particle concentrations were slightly lower. The crustal elements (Mg, Al, and Mn) had higher deposition velocities than anthropogenic elements (V, Cr, Cu, Zn, Mo, Ba and Pb). For crustal elements, overall dry deposition velocities were higher in Chicago than at the other sites.

Long-Term Elemental Dry Deposition Fluxes Measured around Lake Michigan with an Automated Dry Deposition Sampler

Long-term measurements of mass and elemental dry deposition (Mg, Al, V, Cr, Mn, Ni, Co, Cu, Zn, As, Sr, Mo, Cd, Sb, Ba, and Pb) were made with an automated dry deposition sampler (Eagle II) containing knife-edge surrogate surfaces during the Lake Michigan Mass Balance/Mass Budget Study. Measurements were made over a roughly 700-day period in Chicago, IL; in South Haven and Sleeping Bear Dunes, MI; and over Lake Michigan on the 68th Street drinking water intake cribs from December 1993 to October 1995. Average mass fluxes in Chicago, South Haven, Sleeping Bear Dunes, and the 68th Street crib were 65, 10, 3.6, and 12 mg m-2 day-1, respectively. Primarily crustal elemental fluxes were significantly smaller than the mass fluxes but higher than primarily anthropogenic elemental fluxes. For example, the average elemental flux of Al in Chicago, South Haven, Sleeping Bear Dunes, and the 68th Street crib were 1.0, 0.34, 0.074, and 0.34 mg m-2 day-1, respectively. The average Pb fluxes in Chicago, South Haven, Slee...

Duplicate sampling reproducibility of atmospheric residues of herbicides for paired pan and high-volume air samplers

The reproducibility of collection of atmospheric residues of the herbicides 2,4-D and triallate as bulk (wet plus dry) deposition samples by paired pan samplers and as particulate (filter) and vapour (PUF/XAD-2 resin cartridge) samples by paired high-volume air samplers was determined. Variability of herbicide concentrations in paired bulk deposition samples was within 25% for 65 and 80% of the samples for 2,4-D and triallate, respectively, with approximately 90% of the paired samples being within a factor of 2 for both herbicides. The vapour samples of 2,4-D and triallate showed similar reproducibilities. The highest reproducibility was observed for the filter samples with 92% of the paired data sets for 2,4-D being within 25% variability. No triallate was detected in the filter samples.