Vincent A. Dutkiewicz

A long-term (1975-1988) study of atmospheric SO42-: regional contributions and concentration trends.

Abstract A long-term study of aerosol SO42− concentrations ([SO42−]) has been conducted at Mayville in the western and Whiteface Mountain in the northeastern New York State. From 1975 to 1988, 2382 daily aerosol samples were collected at Whiteface Mountain using high-volume samplers. Similarly, 1863 samples were collected at Mayville for the 1981–1988 period. Both sites are downwind of large SO2 sources in the Midwest. Whiteface Mountain is located approximately 600 km to the northeast of Mayville. The [SO42−] at Mayville were approximately twice that of Whiteface Mountain. The highest concentrations at both locations were observed in summer and the lowest during winter. Photochemical reactions appear to be the primary reason for this behavior. Air trajectories (Hefter model) were used to relate the observed [SO42−] with the upwind SO2 source regions. In addition, a method based on V/Se ratios was used to resolve SO42− contributions between Midwestern sources and those in the East Coast. Approximately, two-thirds or more of the total SO42− at the two sites was derived from the Midwestern emissions. At Whiteface Mountain the [SO42−] for summer months from 1975 to 1988 suggest a decrease of approximately 3% per year between 1978 and 1988. A similar decrease was also observed in SO2 emissions.

An evaluation of regional elemental signatures relevant to the Northeastern United States

Abstract Concentrations of sulfate and trace elements measured in high-volume air samples collected at sites in New York State during the summers of 1981, 1982 and 1983 are reported. The sites include Mayville in the westernmost corner of the state, West Haverstraw just north of the metropolitan New York area, and Whiteface Mountain in the Adirondacks. The elemental compositions of the aerosols at these sites are compared. The composition of regional aerosols is investigated using backward-in-time air trajectories to classify samples from Mayville and West Haverstraw into six regions: I, southern Ontario; II, Great Lakes; III, Ohio River Valley; IV, central Pennsylvania; V, western New York; and VI, East Coast urban. Region VI was characterized by high concentrations of V and Sb and relatively low concentrations of the other elements and sulfate. Region III had the highest concentrations of sulfate (28 μg m −3 ) and Se (5 ng m −3 ); both were around 7.5 times higher than for region VI. Crustal elements and bromine were comparable for all regions varying by a factor of two or less. Elemental ratios were explored as tracers for the various regions and the data are also used to test some of the basic assumptions in a proposed multi-element tracer system.

Mn/V ratio as a tracer of aerosol sulfate transport

Abstract Concentrations of SO 4 2− , Al, V and Mn were determined in airborne particles during July-August 1981 at five sites in New York State: for 6-h intervals at Mayville, Brewerton and Whiteface Mountain and for 24-h intervals at Oneonta and West Haverstraw. Episodic high [SO 4 2− ] were observed during 18–21 and 24–26 July and 1–4 August. Air trajectories showed that during the 18–21 July and 1–4 August episodes peak [SO 4 2− ] coincided with slow-moving air masses which had spent 1 or more days in the midwestern states of Indiana, Michigan, Ohio or Pennsylvania prior to entering New York. During the episodes [SO 4 2− ] decreased from west to east. No significant local sources of SO 4 2− exist at the 6-h sites. All these lines of evidence together show that during these episodes SO 4 2− were transported from the industrial Midwest. During the 24–26 July episode, peak [SO 4 2− ] at Mayville coincided with air masses entering the state from Ohio, but at Brewerton and Whiteface Mountain the highest [SO 4 2− ] occurred when air masses came from metropolitan New York City and the mid-Atlantic states. The average [SO 4 2− ] at Mayville were 2-fold higher than at Brewerton and Whiteface Mountain. The average manganese/vanadium ratio (Mn/V) in aerosols from the Midwest (1–10) has been suggested to be ~ 10 times that in the Northeast ( 4 2− ] were due to transport from the Midwest. On 25–26 July the average Mn/V was high at Mayville (2.8) but low at Brewerton (0.29) and Whiteface Mountain (

The relationship between regional SO2 emissions and downwind aerosol sulfate concentrations in the northeastern US.

Our research group has been continuously measuring aerosol sulfate at Whiteface Mountain, New York, since 1979 and at Mayville, New York, since 1984. Monthly aerosol SO2−4 concentrations for these sites are reported here through 1997. Seasonal and long-term profiles of SO2−4 are presented along with SO2 concentrations. As these sites are directly downwind of the high SO2 emission region in the Midwestern United States and the same sampling and analytical protocol has been maintained, they are ideally suited to evaluate long-term trends. The recent reductions in SO2 emissions in response to provisions of the 1990 Clean Air Act provide an excellent opportunity to evaluate the sulfur source–receptor relationship. A linear relationship is demonstrated between aerosol SO2−4 and total sulfur (ST, sum of S present as SO4 and SO2) concentrations at these sites and SO2 emissions upwind in the Midwest. This is the most direct evidence to date that deposition of sulfur in the Northeast is linearly related to upwind SO2 emissions. The results support the possibility of using the ratio of SO2−4/SO2 emissions to develop an empirical source–receptor relationship for the region.

Evidence for decrease in atmospheric sulfur burden in the Eastern United States caused by reduction in SO2 emissions

We report aerosol SO42− measurements from 1979 to 1996 at Whiteface Mountain located in the Adirondack Mountains and from 1983 at Mayville, in western New York State. From 1981 to 1991 SO42− decreased, ∼3% per year. Reductions of nearly 47% in SO42− and total sulfur concentrations at Whiteface Mountain, and about 30% at Mayville, were observed during 1995 to 96 compared with the mean levels during 1981–91, while the upwind SO2 emissions in the Midwestern United States decreased by 36%. Linear relationships between SO42− and total sulfur concentrations and the SO2 emissions were observed for the entire period. The mean ratio of SO42− concentrations to SO2 emissions for the eighteen year period at Whiteface Mountain is 0.11 ± 0.014 and for thirteen years at Mayville is 0.23± 0.014 µg SO42−/m³ per 10³ metric tons SO2 emitted per day. The data suggest that the observed relationship could be used to predict decreases in atmospheric SO42− levels based on SO2 emissions several years hence. Furthermore, it appears feasible to develop an empirical source-receptor relationship if similar data were acquired from a network of strategically located sampling sites.

Semicontinuous PM2.5 sulfate and nitrate measurements at an urban and a rural location in New York: PMTACS-NY summer 2001 and 2002 campaigns.

Abstract Several collocated semicontinuous instruments measuring particulate matter with particle sizes ≤2.5 μm (PM2.5) sulfate (SO4 22−) and nitrate (NO3 −) were intercompared during two intensive field campaigns as part of the PM2.5 Technology Assessment and Characterization Study. The summer 2001 urban campaign in Queens, NY, and the summer 2002 rural campaign in upstate New York (Whiteface Mountain) hosted an operation of an Aerosol Mass Spectrometer, Ambient Particulate Sulfate and Nitrate Monitors, a Continuous Ambient Sulfate Monitor, and a Particle-Into-Liquid Sampler with Ion Chromato-graphs (PILS-IC). These instruments provided near realtime particulate SO4 2− and NO3 − mass concentration data, allowing the study of particulate SO4 2−/NO3 − diurnal patterns and detection of short-term events. Typical particulate SO4 2− concentrations were comparable at both sites (ranging from 0 to 20 μg/m3), while ambient urban particulate NO3 − concentrations ranged from 0 to 11 μg/m3 and rural NO3 − concentration was typically less than 1 μg/m3. Results of the intercomparisons of the semicontinu-ous measurements are presented, as are results of the comparisons between the semicontinuous and time-integrated filter-based measurements. The comparisons at both sites, in most cases, indicated similar performance characteristics. In addition, charge balance calculations, based on major soluble ionic components of atmospheric aerosol from the PILS-IC and the filter measurements, indicated slightly acidic aerosol at both locations.

Regional sources of particulate sulfate, SO2, PM2.5, HCl, and HNO3, in New York, NY

Abstract Simultaneous measurements of gaseous HONO, HNO3, HCl, SO2, and NH3 from July 1999 to June 2000 and fine-fraction particulate (

Availability of H2O2 for oxidation of SO2 in clouds in the Northeastern United States

Abstract A technique using inert tracers was used to determine SO4 formed from in situ oxidation of SO2 by H2O2 in 20 summer clouds at Whiteface Mountain, New York. The amount of in situ SO4 formed, along with H2O2 present in cloud water, was used to determine the total available H2O2. In 11 of the clouds, for which SO2 concentration was

Composition of aerosols and cloud water at a remote mountain site (2.8 kms) in Pakistan

Major ion and trace metal concentrations were determined in aerosols and cloud water at a site in the Himalayan Mountains of Northern Pakistan. In spite of the fact that the site is well removed from significant urban/industrial pollution sources the SO2−4 concentrations in some of the samples were as high as those observed in North America. Concentrations of Se, Tl, Pb, Cl, Cd, Sb, Zn, and As in aerosols were highly enriched relative to average crustal abundances indicating significant anthropogenic contributions. Cloud water concentrations of major ions and trace elements are reported for 18 samples from six different clouds. The pH varied between 5.3 and 6.8 in spite of the fact that the SO2−4 concentration approached 300 μmol in some samples, values often observed in the northeastern US. Selenium was used as a tracer to determine in-cloud production of SO2−4 in these clouds and in three of the six clouds 40–60% of the observed SO2−4 came from in-cloud production.

Case studies of the SO2 + H2O2 reaction in clouds

The in-cloud reaction between SO2 and H2O2has been investigated using data from field campaigns of July 1995 and July–August 1997 at Whiteface Mountain, New York. Cloud water samples were collected at the mountains summit (1.5 km, above mean sea level (amsl)), and aerosols in clear air at a site (Lodge) located at 0.6 km amsl and in cloud interstitial air at the summit. Cloud water and aerosol samples were analyzed for SO42− and selected trace elements. Gaseous SO2 and H2O2 were measured at both sampling sites. Criteria based on total sulfur and O3 concentrations were developed to decide when the two sites were coupled (i.e., air masses at the two sites had the same composition for the chemical species studied). Four case studies are presented that exhibit varying concentration levels and different meteorological conditions. In two cases the sites were coupled, and in two others they were decoupled. The clouds showed high pollutant concentrations with a mean pH of 3.5. A tracer technique was used to quantitatively determine the SO42− produced from in situ SO2 oxidation. In general, good agreement between the SO2 consumed and SO42− produced was observed. Similarly, H2O2 concentrations in precloud air showed stoichiometric mass balance with the sum of H2O2 observed in cloud interstitial air, in cloud water, and equimolar amounts needed to produce SO4in2− as determined by the tracer technique. Data from all 24 clouds showed that (1) ∼28% of the cloud water SO42− was due to in situ oxidation; (2) ∼75% of the SO2 in the precloud air was oxidized in situ at Whiteface Mountain; (3) the mean SO2 concentration in air masses associated with cloudy periods is approximately 1.4 ppb, significantly higher than the summer average of 0.5 ppb; (4) the mean H2O2 concentration in cloud-free periods during summer is 1.1 ppb sufficient to oxidize SO2 present; (5) the frequent presence of H2O2 in cloud water indicated that the reaction had not often reached completion.