A statewide investigation of insecticide presence and sediment toxicity was conducted in Illinois, USA, from June to August 2008. Twenty sediment samples were collected from urban areas throughout Illinois, and 49 sediment samples were collected from 14 agriculture-dominated counties in central and southern Illinois. Ten-day sediment toxicity tests were conducted using the amphipod Hyalella azteca, and 59% of the urban sites and 2% of the agricultural locations sampled caused significant mortality in the amphipods. The field sediments were analyzed for 29 pesticides, including 19 organochlorines, one organophosphate, and nine pyrethroids. The detection frequencies of organochlorines, chlorpyrifos, and pyrethroids were 95, 65, and 95%, respectively, for urban sites, and 45, 6.1, and 47%, respectively, for agricultural sites. Based on toxic unit analysis, bifenthrin was the main contributor to the detected mortality in urban sediments. The present study provides the first broad assessment of pesticide prevalence in both urban and agriculture areas in Illinois.
Fine particulate mass will frequently be signi cantly underestimated in urban environments using current EPA federal reference method (FRM) single lter samplers because of loss of semivolatile organic material and nitrate from the particles during sampling. Previously described diffusion denuder samplers, such as the Brigham Young University organic sampling system (BOSS) and BIG BOSS, eliminate both positive and negative sampling artifacts by removing the gas-phase material before ne particulate mass is collected on a quartz lter and a sequential sorbent lter or bed. However, these samplers are not amenable to routine eld use because they require multiple systems to accurately account for the ef ciency of the denuder for each sample. The denuder ef ciency is substantially improved by combining a conventional 2.5 ¹m cutpoint inlet and a low cutpoint virtual impactor particle concentrator to provide concentrated ne particles (0.1-2.5 ¹m) to a BOSS diffusion denuder sampling system (PC-BOSS). The performance of both the particle concentrator and the diffusion denuder in the PC-BOSS has been evaluated. Under optimized conditions, the minor to total ow ratio for the concentrator is 25% and the concentrator ef ciency is 70-90% for sulfate and 60-85% for soot, depending on the particle size distribution of these species. The particle loss in the concentrator is about 6%. The particle loss in the denuder system is negligible. At the recommended optimum minor ow (concentrated particles, 25% of the total ow), most of the gas-phase material is discarded by the particle concentrator before the concentrated ne particles enter the diffusion denuder. At an optimized inlet ow of 150 L/min with a ow through the denuder of 38 L/min, the overall ef ciency of the PC-BOSS for the removal of gas-phase organic material, SO 2 , and HNO 3 is over 99%.
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