Accumulation of Polychlorinated Biphenyls and Polycyclic Aromatic Hydrocarbons in the Snowpack of Minnesota and Lake Superior (original) (raw)
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Snow Scavenging of Polychlorinated Biphenyls and Polycyclic Aromatic Hydrocarbons in Minnesota
Environmental Science & Technology, 1998
Snow and rain events were collected with concurrent air samples during the winter of 1991-1992 at a suburban site in Minnesota to investigate atmospheric scavenging of polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs). Particle scavenging was the dominant contributor to the total concentrations in snow and was less important in rain. Gas scavenging was only important for low molecular weight PCB congeners and PAHs. Enrichment of dissolved-phase concentrations over levels predicted from temperature-corrected Henry's Law constants was observed for low molecular weight compounds in both rain and snow. The particulate fraction (φ) of atmospheric PCBs and PAHs was the best indicator of total scavenging (W T) by snow according to the equations log W T) 0.71 ((0.08) log φ + 5.34 ((0.08) for PCB congeners (r) 0.62) and log W T) 0.89 ((0.12) log φ + 6.07 ((0.13) for PAHs (r) 0.73).
Deposition of atmospherically transported polychlorinated biphenyls in the Canadian arctic
Chemosphere, 1996
Snow collectors were installed in 1990 at two Canadian high arctic weather stations (Mould Bay {MB} and Eureka {EU}) in an effort to estimate annual deposition of PCBs, compare these estimates to annual snowpack measurements and to investigate the timing of the deposition. The collectors operated successfully but tended to over collect when two snow fences were used. The daily flux of ~PCBs in the snowpack for 1990/91 generally compared well to that of the snow collector at MB. The snowpaek sample at EU for the same period was considered to be unrepresentative, due to low snow accumulation on the ground and high winds, with resulting low concentrations and fluxes. The congener makeup of snowpack and snow collector samples was similar for both sites. Mean ~PCB fluxes for the collectors for the winter season were 2.0 and 3.8 ng. m "2. day "t for MB and EU respectively. Due to the tendency of the collectors to overeatch, especially late in the season, the fluxes were corrected relative to the shielded Nipher Gauge used to measure snowfall at the weather stations. The corrected ~PCB fluxes for MB reduced the overall contribution of a high concentration event in the winter, in favour of the fall season, the time of greatest snow accumulation. Initial assessment of the collectors for measuring the timing of and composition of PCB deposition to the arctic is very encouraging. Work is continuing to improve the collectors and to provide a better estimate of deposition of organic contaminants to the arctic environment.
Environmental Science & Technology, 2001
Air samples were collected simultaneously at three sites downwind of Lake Ontario and at a control site near Lake Erie from March to July of 1999. The Lake Erie site (Stockton, NY) had PCB concentrations similar to rural Integrated Atmospheric Deposition Network (IADN) sampling sites across the Great Lakes, exhibited limited seasonal variation, and approximates regional background. Samples taken along Lake Ontario's southeastern shore (Rice Creek and Sterling, NY) had elevated PCB concentrations averaging ∼1 ng/m 3 and were more chlorinated than air collected at IADN sites and at Stockton. Air samples from Potsdam (∼75 km inland) had similar concentrations but were less chlorinated. Clausius-Clapeyron plots revealed a strong correlation between PCB fugacity and temperature near Lake Ontario; however, the extent of chlorination of the air samples rules out volatilization from the lake as a major source. It is hypothesized that volatilization from local surfaces, enriched in higher chlorinated congeners by meteorological or geographic factors, drives both the concentration and composition of airborne PCBs along Lake Ontario's southeastern shore.
Polycyclic aromatic hydrocarbons in air and snow from Fairbanks, Alaska
There has been increasing interest regarding the use of passive air samplers as tools for monitoring organic pollutants in the atmosphere. In this study we report results obtained from passive air samplers that were deployed in both indoor and outdoor environments across the City of Fairbanks, AK, for the polycyclic aromatic hydrocarbons (PAHs) during winter 2009. It is demonstrated that the passive air samplers provide reliable data for the gas-phase PAHs. Results for particulate-phase isomers, however, are more variable and thus likely to be less reliable. For instance, the use of passive air samplers in indoor environments does not appear effective for distinguishing between homes with and without wood stoves, largely due to discrepancies associated with measuring particulatephase PAHs. Consequently, it is suggested that the passive air samplers should not be used for assessing indoor exposures to particulate-bound pollutants. Nevertheless, air concentrations obtained from active air samplers indicate that PAHs in air are dominated by the gas-phase isomers, resulting in good agreement between the active and passive air samplers for outdoor air. The average passive indoor air concentrations for ΣPAH 20 are observed to be slightly higher than passive outdoor air concentrations, at 55 and 26 ng m -3 respectively. Concentrations in outdoor air for the City of Fairbanks are reported to be an order of magnitude lower during 2009 than during the winter of 1976/77, when they were last reported. Snow data for the PAHs are reported as a complement to the air concentration data, showing similar isomer patterns between air and undisturbed snowpack samples. Snow samples collected from snow dump collection sites are reported to be 25 times greater than nearby undisturbed snow, and are dominated by the particulate-phase PAHs. Recommendations for future monitoring of snowmelt from the snow dump collection sites are suggested.
Environmental Science & Technology, 1990
W Concentrations of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) were measured in the atmosphere and surface waters of Lake Superior to estimate the direction and magnitude of their fluxes across the air-water interface. Atmospheric PAH concentrations (C[PAH] = 3.8 f 1.7 mg/m3, 13 PAHs) were typical of levels found in continental background air. Atmospheric PCB concentrations (x = 1.2 ng/m3) have remained relatively constant over the Great Lakes during the past 10 years despite lower PCB loadings. PCB congener fugacity gradients suggest PCB volatilization from Lake Superior's surface waters in August 1986. Mean volatilization fluxes of total PCBs (19 ng/m2.day) are similar to estimates of gross atmospheric deposition to the lake, supporting the hypothesis of nonequilibrium, steady-state PCB exchange across the air-water interface. PAH fluxes could not be calculated due to uncertainties in PAH Henry's law constants.
Environmental Science & Technology, 1998
Dry deposition was collected from November 1993 to October 1995 at multiple sites within the Lake Michigan basin to estimate fluxes of particulate polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) as part of the Lake Michigan Mass Balance Study (LMMBS). Samples were also collected during the Atmospheric Exchange over Lakes and Oceans (AEOLOS) project to estimate fluxes to coastal waters adjacent to the Chicago urban area. Fluxes of particulate PCBs and PAHs were higher in Chicago than <15 km offshore and at rural sites. Geometric mean dry deposition fluxes across the Lake Michigan basin ranged from 3.6 to 65 mg/m 2day for particle mass, 0.06 to 0.21 µg/m 2 -day for Σ-PCBs, and 0.25 to 18 µg/m 2 -day for Σ-PAHs. Similarities in both the distribution pattern of PCB congeners and PAHs and the magnitude of their fluxes between dry deposition and surficial sediment suggest that dry deposition may dominate loadings to the lake. Conservative estimates of loadings to Lake Michigan through particle dry deposition are estimated to be 1100 kg/yr for PCBs and 5000 kg/yr for PAHs. These loadings are more than 3× greater than loadings by wet deposition and, for PCBs, are similar to inputs by air/ water exchange. flux (µg/m 2 -day) ) C a,p (ng/m 3 ) × V d (cm/s) × 0.864
Assessing Annual Water-Air Fluxes of Polychlorinated Biphenyls in Lake Michigan
Environmental Science & Technology, 1995
Air-water exchange of PCBs was determined in Lake Michigan on an event and seasonal basis in 1991 -1993. Instantaneous fluxes of CPCB (sum of 77 congener peaks) based on air-water concentration gradients drawn from air and water samples collected simultaneously aboard ship demonstrated net volatilization in September 1991. Air samples collected on the northeastern shore of Lake Michigan (Sleeping Bear Dunes State Park) between December 1991 and July 1993 showed no seasonal trend in vapor-phase CPCB concentrations and ranged from 30 to 400 pg/m3. These air concentrations were used to calculate seasonal water-air fluxes of CPCB that ranged from -18 ng m-2 day-' (net deposition) to 60 ng m-2 day-' (net volatilization). The seasonal variation of vapor-phase and dissolved-phase PCBs in the impacted southern quarter of the lake are unknown, thereby hindering estimation of fluxes in this region. The estimated annual net CPCB flux is 12.3 p g m-2 yr-', which corresponds to 520 kg for the northern three-quarters of Lake Michigan.
Environmental Science & Technology, 1998
PCB congener concentrations in air, water, fish, and snow were determined in the Lake Tahoe basin and in the water and fish of an adjacent but more remote rural comparison lake, Marlette Lake, to examine whether atmospheric transport and deposition are primary sources of contamination to this alpine region of the Sierra Nevada Mountains. Profiles of 97 congeners analyzed by capillary GC-ECD from surface waters of Lake Tahoe and Marlette Lake were closely matched, with total dissolved PCB (t-PCB) concentrations of 0.37 ng/L in Lake Tahoe and 0.67 ng/L in Marlette Lake. Gas-phase t-PCB concentrations measured in air samples from the Lake Tahoe basin averaged 72 pg/m 3 , and t-PCB (dissolved and particulate) concentrations in snow were 4.8-5.1 ng/L. Rainbow trout from Marlette Lake and lake trout from Lake Tahoe had similar distributions of congeners, with t-PCB tissue levels varying from 3 to 14 ng/g wet weight. The finding of PCBs in all sampled compartments, particularly snow and air, and the similar pattern of congeners in surface waters and in fish from Lake Tahoe and Marlette Lake indicate an atmospheric source of contamination.
Concentrations of Airborne PCBs Over Lake Michigan
Journal of Great Lakes Research, 1981
ABSTSRA CT. Air samples were collected on Lake Michigan and analyzed for polycholorinated biphenyls (PCBs). Concentrations of PCBs in air from two urban areas (Milwaukee and Madison, Wisconsin) were also measured for comparison purposes. Values of PCB concentrations (filterable + nonfilterable) in air over Lake Michigan exhibited both a lower average (l.0 ng/m 3 ) and a narrower range (0.63 -1.46 ng/ m 3 ) than those from the urban areas (-5 ng/ m 3 and 0.8 -8.07 ng/ m 3 , respectively). The average ratio offilterable to nonfilterable airborne PCBs, thought to be a reasonable indication of particulate vapor phase partitioning, was about 1:11 for the three sampling locations. The PCB vapor composition at the three sampling areas was predominantly Aroclor 1242. Particulate PCBs over Lake Michigan were enriched in Aroclor 1242 when compared to those collected in Milwaukee and Madison.