Annual variations of pesticide concentrations in Great Lakes precipitation

Twenty pesticides and related analytes were measured in 28-day integrated precipitation samples from five U.S. sites in the Integrated Atmospheric Deposition Network (IADN) between 1997 and 2002. Consistent, significant decreases in concentration as a function of time were observed only for p,p'-DDE and p,p'-DDD, while increases in beta-HCH were observed at all sites. Significant annual variations were observed for most analytes at each site with higher concentrations in the summer for current-use pesticides (endosulfan and gamma-HCH) and peaks in the winter for most others. The increased concentrations in the winter are likely the result of the increased scavenging efficiency of snow compared to rain and, for some analytes, higher concentrations in the particulate phase during winter. These seasonal differences appear to account for a large portion of the observed variability in pesticide concentrations in precipitation samples.     

Dechlorane plus in the atmosphere and precipitation near the Great Lakes

Air (vapor and particle) and precipitation samples were collected at five sites (two urban, one rural, and two remote) on the shores of the Great Lakes from January 1, 2005 to December 31, 2009 as a part of the Integrated Atmospheric Deposition Network (IADN). The concentrations of the syn and anti isomers of Dechlorane Plus (DP), a highly chlorinated flame retardant, were measured in these samples. The highest concentrations of these compounds were generally observed at the rural site at Sturgeon Point, New York, which is located near DP's manufacturing facility in Niagara Falls, New York, and at the urban site at Cleveland, Ohio. A multiple linear regression model was applied to the concentrations of these compounds in the vapor phase, particle phase, precipitation, and for the three phases combined. This regression resulted in an overall (three phases combined) doubling time for the anti-DP isomer of 9.5 ± 3.6 years, but for the syn- and total DP (syn + anti) concentrations, the overall regression was not statistically significant. These results suggest that there has been no significant change in the atmospheric concentrations of these compounds over the 2005-2009 time period. The effect of distance from the source in Niagara Falls was highly significant; for example, doubling the distance from Niagara Falls decreased the DP concentrations by about 30%. The effect of the number of people living and working within a 25-km radius of the sampling site (population density) was also highly significant but small; for example if this population doubled or halved, then the atmospheric DP concentrations would increase or decrease by only a few percent.     

Trends in polycyclic aromatic hydrocarbon concentrations in the great lakes atmosphere

Atmospheric polycyclic aromatic hydrocarbon (PAHs) concentrations were measured in both the vapor and particle phases at seven sites near the Great Lakes as a part of the Integrated Atmospheric Deposition Network. Lower molecular weight PAHs, including fluorene, phenanthrene, fluoranthrene, and pyrene, were dominant in the vapor phase, and higher molecular weight PAHs, including chrysene, benzo[a]pyrene, and coronene, were dominant in the particle phase. The highest PAH concentrations in both the vapor and particle phases were observed in Chicago followed by the semiurban site at Sturgeon Point, NY. The spatial difference of PAH concentrations can be explained by the local population density. Long-term decreasing trends of most PAH concentrations were observed in both the vapor and particle phases at Chicago, with half-lives ranging from 3-10 years in the vapor phase and 5-15 years in the particle phase. At Eagle Harbor, Sleeping Bear Dunes, and Sturgeon Point, total PAH concentrations in the vapor phase showed significant, but slow, long-term decreasing trends. At the Sturgeon Point site, which was impacted by a nearby city, particle-phase PAH concentrations also declined. However, most particle-phase PAH concentrations did not show significant long-term decreasing trends at the remote sites. Seasonal trends were also observed for particle-phase PAH concentrations, which were higher in the winter and lower in the summer.     

Influence of local human population on atmospheric polycyclic aromatic hydrocarbon concentrations

Literature values of atmospheric polycyclic aromatic hydrocarbon (PAH) concentrations from sampling sites around the world were found, and using a high-resolution human population grid, the population within a 25-km radius of each sampling site was calculated. A regression of concentration vs population revealed much about PAH concentration differences among regions as well as site locations within a continent. The best fit for the regression was for sampling locations in North America. A small amount of scatter was present for the regression of all developed countries indicating slight differences in emission regulations or energy usage. The regression from this plot was used as a benchmark for the expected relationship between PAHs and human population. Sites located within 25 km of a coasttended to have concentrations lower than expected, due to dilution with clean ocean air, while sites near industrial outputs or other point sources had higher than expected concentrations. Sites from developing countries typically had PAH concentrations that were far higher than those of the rest of the world.     

Causes of variability in pesticide and PCB concentrations in air near the Great Lakes

Data through 2001 from the Integrated Atmospheric Deposition Network (IADN) were used to investigate the causes of variability in gas-phase polychlorinated biphenyl (PCB) and pesticide concentrations measured near Lakes Michigan, Erie, and Superior. A multiple linear regression model that incorporates temperature and time was used explain the variability in the concentrations. Our approach used autocorrelation analyses of the residuals to help us determine the effectiveness of the regression. Autocorrelation plots forthe in-use pesticide lindane indicated that an agricultural application cycle was also present in the regression residual data at all sites. The addition of parameters for this effect to the regression equation accounted for, on average, 16% more of the variability in the data. Similar analyses forthe in-use pesticide endosulfan did not show an agricultural application effect. The banned compounds DDT and chlordane showed that temperature and time correctly accounted for the variability in the atmospheric concentrations of these compounds at all sites. In contrast to the other compounds, PCBs and hexachlorobenzene showed strong residual autocorrelation patterns near Lake Michigan of an unknown origin.     

Temporal and spatial trends of atmospheric polychlorinated biphenyl concentrations near the Great Lakes

Polychlorinated biphenyl (PCB) concentrations were measured in the atmosphere at six regionally representative sites near the five Great Lakes from 1990 to 2003 as part of the Integrated Atmospheric Deposition Network (IADN). Concentration data for several individual PCB congeners and for total PCBs were analyzed for temporal and spatial trends after correcting for the temperature dependency of the partial pressures. Atmospheric PCB concentrations are decreasing relatively slowly for tetra- and pentachlorinated congeners, an observation that is in agreement with primary emissions modeling. Relatively rapid decreases in PCB concentrations at the sites near Lakes Michigan and Ontario may reflect successful reduction efforts in Chicago and Toronto, respectively. Atmospheric PCB concentrations near Lakes Superior and Huron are now so low that the air and water concentrations may be close to equilibrium. Atmospheric PCB concentrations at sites near Lakes Michigan, Erie, and Ontario are relatively higher than those measured at sites near Lakes Superior and Huron. The highest PCB level was observed at the site near Lake Erie, most likely due to nearby urban activity. However, this relatively higher concentration is still 6-10 times lower than that previously reported at the Chicago site. A correlation between average gas-phase PCB concentration with local population indicates a strong urban source of PCBs. The temperature dependence of gas-phase PCB concentrations is similar at most sites except at Burnt Island on Lake Huron, where very low concentrations, approaching virtual elimination, prevent reliable temperature correlation calculations.     

Atmospheric organochlorine pesticide concentrations near the Great Lakes: temporal and spatial trends

As a part of the Integrated Atmospheric Deposition Network, atmospheric organochlorine pesticide concentrations were measured in both the gas and particle phases at seven sites near the Great Lakes. Much higher organochlorine pesticide concentrations were found in the gas phase compared to that in the particle phase. Long-term decreasing trends were observed for most pesticides in both phases. Two different seasonal trends were observed in the particle phase: (a) in-use pesticides, such as endosulfan, showed higher concentrations in the summer, a time corresponding to their agriculture use, and (b) restricted organochlorine pesticides, such as lindane, showed higher particle-phase concentrations in the winter, presumably due to their enhanced partitioning from the gas phase to particles. Generally, Chicago had the highest concentrations of chlordanes, dieldrin, and sigmaDDT, suggesting that urban areas could be sources of these compounds to atmosphere. Point Petre had the highest concentrations of endosulfan, likely due to its agricultural application in Southern Ontario.     

Gas-phase polychlorinated biphenyl and hexachlorocyclohexane concentrations near the Great Lakes: a historical perspective

The Integrated Atmospheric Deposition Network (IADN) has been measuring gas-phase, polychlorinated biphenyl (PCB) concentrations at sites near Lakes Michigan and Superior for over a decade. Data through 2000 were used in this study to investigate PCB temporal trends in the Great Lakes atmosphere. Decreasing trends were found at both sites, and half-lives of approximately 20 yr were calculated using IADN data. However, when these data were supplemented by historical data for Lakes Michigan and Superior dating back to 1977, half-lives dropped to 10 and 6 yr, respectively. These latter half-lives agreed well with half-lives in other environmental compartments. Exponential curves fitted to the historical and IADN data indicated little decline in PCB concentrations in the basin since the mid-1990s. A similar historical analysis of alpha-and gamma-hexachlorocyclohexane (HCH) data indicated that IADN data were the best predictor of trends, resulting in half-lives of around 4 yr for both compounds. Gamma-HCH concentrations, however, have shown little decline in recent years, most likely because of its continuing use. PCB and alpha-HCH temporal trends indicated that bans on these substances have helped to remove them from the atmosphere. This work also showed that decades of data may be necessary to properly interpret long-term temporal trends in gas-phase organochlorine concentrations.     

Flame retardants in the atmosphere near the Great Lakes

As part of the Integrated Atmospheric Deposition Network (IADN), air samples were collected at five sites around the Great Lakes (two urban, two rural, and one remote) every 12 days during 2005-2006, and the concentrations of polybrominated diphenylethers (PBDEs), 1,2-bis(2,4,6-tribromophenoxy)-ethane (TBE), Dechlorane Plus (DP), and decabromodiphenyl ethane (DBD PE) were measured. The highest mean concentrations of total PBDEs were found at the urban sites in Chicago and Cleveland (65 +/- 4 and 87 +/- 8 pg/m3, respectively), and the lowest at the remote site in Eagle Harbor (5.8 +/- 0.4 pg/m3). With the exception of Chicago, the atmospheric concentrations of BDE-47 and 99 (summed over the gas and particle phases) are decreasing rapidly with half-lives of approximately 2 years, but the concentrations of BDE-209 are not decreasing at any of the five sites. The atmospheric partial pressures of BDE-47 and 99 showed a strong Clausius-Clapeyron relationship with reciprocal atmospheric temperature. TBE, DBDPE and DP were detected at all sites, but with the exception of Chicago, there were insufficient data to determine temporal trends for these compounds. The influence of human population density and synoptic atmospheric transport patterns was explored to explain the relatively high concentrations of BDE-209 in Cleveland.     

Preparation and stability of ampouled polycyclic aromatic hydrocarbon solutions

Summary A 1-year stability study of ampouled polycyclic aromatic hydrocarbon (PAH) solutions was carried out. Two solutions of seven pure PAHs were prepared, one in acetonitrile and one in toluene, and ampouled. Solutions were tested for mass concentration and impurities before and after ampouling. No differences were found. After 0, 3, 6, 9 and 12 months, three ampoules were selected for analysis from the acetonitrile and the toluene lots stored at +20° and at –20 °C. The acetonitrile solution was analysed by high performance liquid chromatography and the toluene solution by glass capillary gas chromatography. The results demonstrate that both solutions were stable and no contamination. occurred during storage.

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Herstellung und Stabilität von polycyclischen aromatischen Kohlenwasserstofflösungen in Ampullen

Zusammenfassung Für eine einjährige Studie über die Stabilität von PAK-Lösungen in Ampullen wurde je eine Lösung von sieben reinen polycyclischen aromatischen Kohlenwasserstoffen in Acetonitril und in Toluol hergestellt und in Ampullen eingeschlossen. Die Lösungen wurden vor und nach dem Einschluß in Ampullen auf ihren Gehalt und ihre Zusammensetzung untersucht, wobei keine Abweichungen festgestellt wurden. Nach 0, 3, 6, 9 und 12 Monaten wurden jeweils drei Ampullen der bei –20 °C and +20 °C gelagerten Lösungen untersucht, und zwar die Acetonitrillösung mit Hochdruckflüssigchromatographie und die Toluollösung mit Capillar-Gaschromatographie. Die Ergebnisse zeigen, daß beide Lösungen während der ganzen Lagerungszeit stabil und kontaminationsfrei waren.

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This study has been carried out on behalf of the Community Bureau of Reference (BCR) Brussels/Belgium — Commission of the European Communities Contract BCR 2093/1/5/204/85/2-BCR-NL(10) of April 12th. 1985     

Preparation and stability of ampouled polycyclic aromatic hydrocarbon solutions

A 1-year stability study of ampouled polycyclic aromatic hydrocarbon (PAH) solutions was carried out. Two solutions of seven pure PAHs were prepared, one in acetonitrile and one in toluene, and ampouled. Solutions were tested for mass concentration and impurities before and after ampouling. No differences were found. After 0, 3, 6, 9 and 12 months, three ampoules were selected for analysis from the acetonitrile and the toluene lots stored at +20 degrees and at -20 degrees C. The acetonitrile solution was analysed by high performance liquid chromatography and the toluene solution by glass capillary gas chromatography. The results demonstrate that both solutions were stable and no contamination occurred during storage.     

Effects of wind and air trajectory directions on atmospheric concentrations of persistent organic pollutants near the Great Lakes

Three different regression models involving air temperature, time, and either wind direction or parametric or nonparametric air trajectory direction were used with concentrations of four representative persistent organic pollutants to quantitate the atmospheric transport of these compounds to the Great Lakes. The local wind and parametric trajectory models predicted an optimal source direction for each compound, whereas the nonparametric trajectory model was based on a hypothesized source region. All three regressions were used to calculate the factor by which the partial pressures of each compound measured at five sampling sites increased when the air came from a particular source direction. Dieldrin, chlordane, polychlorinated biphenyl, and polycyclic aromatic hydrocarbon partial pressures were used with each of these regressions, and the correlation coefficients (r2) were evaluated for each model, for each compound, and for each regression term. In general, with the exception of polycyclic aromatic hydrocarbons at some sites, the explanatory powers of the regressions were not improved by the inclusion of any of these directional terms.     

Remediation of polycyclic aromatic hydrocarbon compounds in groundwater using poplar trees

A seven-year study was conducted to assess the effectiveness of hybrid poplar trees to remediate polycyclic aromatic hydrocarbon (PAH) compounds in soil and groundwater at a creosote-contaminated site. A reduction in the areal extent of the PAH plume was observed in the upper half of the 2-m-thick saturated zone, and PAH concentration levels in the groundwater declined throughout the plume. PAH concentrations began to decline during the period between the third and fourth growing seasons, which coincided with the propagation of the tree roots to the water table region. Remediation was limited to naphthalene and several three-ring PAHs (acenaphthylene and acenaphthene). PAH concentrations in soil and aquifer sediment samples also declined over time; however, levels of four-ring PAHs persisted at the lower depths during the study period. The naphthalene to total PAH concentration ratio in the most contaminated groundwater decreased from >0.90 at the beginning of the second growing season to approximately 0.70 at the end the study. Remediation in the lower region of the saturated zone was limited bythe presence of a 0.3-m-thick layer of creosote present as a dense nonaqueous phase liquid (DNAPL). The nearly steady-state condition of the PAH concentrations observed during the last three years of the study suggests that the effectiveness of the phytoremediation system is limited by the rate of PAH dissolution from the DNAPL source.     

Temporal and spatial trends of organochlorine pesticides in Great Lakes precipitation

Organochlorine pesticide concentrations in precipitation samples collected from 1997 to 2003 at seven Integrated Atmospheric Deposition Network sites around the Great Lakes are reported. The 28-day volume weighted mean concentrations of several pesticides, including gamma-hexachlorocyclohexane (HCH), endosulfan, hexachlorobenzene, chlordane, and DDE, showed significant seasonal trends. For current-use pesticides (endosulfan and gamma-HCH), their concentrations peaked in late spring to summer just after their agricultural application. For the banned pesticides, higher concentrations were observed in the winter due to their enhanced partitioning to particles and scavenging by snow. Long-term decreasing trends were observed for several pesticides such as gamma-HCH and DDE. On the other hand, beta-HCH showed significant increasing concentrations as a function of time at Brule River, Eagle Harbor, and Sleeping Bear Dunes. Generally, Chicago had the highest concentration of chlordanes, dieldrin, and DDT, indicating that urban areas could be a source for these compounds to precipitation. For gamma-HCH and endosulfans, Point Petre had the highest concentrations due to the application of these pesticides in the surrounding areas.     

Evaluation of methods for predicting the toxicity of polycyclic aromatic hydrocarbon mixtures

Risk assessments of polycyclic aromatic hydrocarbon mixtures are hindered by a lack of reliable information on the potency of both mixtures and their individual components. This paper examines methods for approximating the toxicity of polycyclic aromatic hydrocarbon (PAH) mixtures. PAHs were isolated from a coal tar and then separated by ring number using HPLC. Five fractions (A-E) were generated, each possessing a unique composition and expected potency. The toxicity of each fraction was measured in the Salmonella/mutagenicity assay and the Chick Embryo Screening Test (CHEST). Their abilities to induce ethoxyresorufin-O-deethylase and to inhibit gap junction intercellular communication in rat liver Clone 9 cells were also measured. In the Salmonella/mutagenicity assay, fractions were predicted to have potencies in the order C > D > E > B > A. Toxic equivalency factors (TEFs) for fractions A-E were in the order E > or = D > C > B > A. TEF values were 20,652, 20,929, 441, 306, and 74.1 micrograms of BaP equiv/g, respectively. A lack of agreement between assay-predicted potencies and chemical analysis-predicted potencies was observed with other assays and other methods of calculation. The results demonstrate the limitations of using a single method to predict the toxicity of a complex PAH mixture.     

Evolution of the concentrations of polycyclic aromatic hydrocarbons in burnt woodland soils

Little is known of the fate of polycyclic aromatic hydrocarbons (PAHs) in soils under burnt woodland. It is not clear what the behavior of the overlying wood ash layer will be along months. In this study, the levels of eight representative PAHs in the 1-5 cm layer of a periurban woodland soil that had undergone wildfire were compared with those measured in nearby and distant unburnt periurban woodland soils and in a distant unburnt rural woodland soil, and the levels at the burnt site were monitored during some 10 months. The analytical method optimized for the purpose afforded recoveries of 74-111% (depending on PAH) and repeatabilities (RSDs) better than 9%, with limits of detection ranging from 1 to 7 microg/kg. PAH levels in the 1-5 cm layer of the burnt periurban soil were very similar to those of distant unburnt periurban soil (188 vs 173 microg/kg), about seven times the 26 microg/kg measured in unburnt rural soil, which furthermore contained no detectable quantities of the highest molecular weight PAHs typical of traffic and other urban sources, as the periurban soils did. At the burnt site, PAH levels fell along the months (the total PAH level from 188 to 119 microg/kg), apparently as the result of rainfall and the prevention of further input from the atmosphere by the overlying layer of wood ash, which had a very high PAH adsorption capacity (1169 microg/kg) and did not itself appear to act as a source of PAHs. PAH transport may have been assisted by increased mobilization of PAHs associated with dissolvable organic matter due to an increase in soil pH due to alkaline ash components.     

焙炒条件对芝麻油中多环芳烃含量的影响

对芝麻进行不同条件焙炒实验,榨取芝麻油,之后对不同焙炒条件下芝麻油中多环芳烃含量进行检测分析。结果表明:随着焙炒时间的延长、焙炒温度的升高,芝麻油中B[a]P、PAH4、PAH16的含量都呈现明显上升趋势;对照国标GB 2716—2005及欧盟No835/2011号法规关于B[a]P和PAH4的限量,芝麻籽的合理焙炒时间不宜超过30 min,焙炒温度不宜超过200℃;焙炒时间为30 min的条件下,焙炒温度在200~240℃之间时,有利于3环物的积累,而焙炒温度达到260℃时,则有利于4环物及重质多环芳烃的积累。     

Assessment of the dietary habits and polycyclic aromatic hydrocarbon exposure in primary school children

Thirty Italian children, 7–9 year aged, living in Naples were investigated on their dietary habits and on polycyclic aromatic hydrocarbon (PAH) exposure by a food diary-questionnaire and one week duplicate diet sample analyses. Daily total food consumption mean value was 632 ± 215 g day^?1, median value 613 g day^?1. The daily energy intake and the diet composition meanly agreed with the official guidelines for the Italian children. Sixteen PAHs were simultaneously detected and, according to the European Food Safety Authority (EFSA) approach, benzo[a]pyrene; benzo[a]pyrene + chrysene (PAH2); PAH2 + benz[a]anthracene + benzo[b]fluoranthene (PAH4); PAH4 + benzo[k]fluoranthene + benzo[ghi]perylene + dibenz[a, h]anthracene + indeno[1,2,3-cd]pyrene (PAH8) were considered in evaluating the children's dietary exposure to PAHs. The benzo[a]pyrene (BaP) median concentrations in foods varied from 0.06 to 0.33 µg kg^?1. Only three samples of cooked foods (one fish and two meat samples) exceeded legal limits fixed by the European Union for BaP. Daily median intakes of benzo[a]pyrene, PAH2, PAH4, and PAH8 were 153; 318; 990; 1776 ng day^?1; their median exposure values were 5; 10; 28; 54 ng kg^?1 bw day^?1. The Margins of Exposure (MOEs) in median consumers agreed with the EFSA safety values except for PAH8.