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Particulate matter (PM) emitted from fossil fuel-fired units can be classified as either filterable or condensible PM. Condensible PM typically is not measured because federal and most state regulations do not require sources to do so. To determine the magnitude of condensible PM emissions relative to filterable PM emissions and to better understand condensible PM measurement issues, a review and analysis of actual U.S. Environmental Protection Agency (EPA) Method 202 (for in-stack condensible PM 10 ) and EPA Method 201/201A (for in-stack filterable PM 10 ) results were conducted. Methods 202 and 201/201A results for several coal-burning boilers showed that the condensible PM, on average, comprises approximately three-fourths (76%) of the total PM 10 stack emissions. Methods 202 and 201/201A results for oil-and natural gas-fired boilers showed that the condensible PM, on average, comprises 50% of the total PM 10 stack emissions. Methods 202 and 201/201A results for oil-, natural gas-, and kerosene-fired combustion turbines showed that the condensible PM, on average, comprises 69% of the total PM 10 stack emissions. Based on these limited measurements, condensible PM can make a significant contribution to total PM 10 emissions for fossil fuel-fired units. A IMPLICATIONS This study examines issues associated with the measurement of a form of PM, condensible PM, that is not routinely accounted for in assessing compliance with PM emission limits. The data analyzed in this study show that condensible PM constitutes a significant fraction of total PM 10 emissions for fossil fuel-fired units, although there is some controversy associated with the in-stack measurement methodology, EPA Method 202. The accounting of condensible PM for existing units could prompt permit re-openings and PM 10 emission limit revisions. For some sources, both existing and new, demonstrating compliance with PM air quality standards could be difficult.

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Maryland will impose restrictions on poultry litter application to soils with excessive P by the year 2005. Alternative uses for poultry litter are being considered, including burning as a fuel to generate electricity. The resulting ash contains high levels of total P, but the availability for crop uptake has not been reported. Our objective was to compare the effectiveness of poultry litter ash (PLA) and potassium phosphate (KP) as a P source for wheat (Triticum aestivum L.) in acidic soils, without and with limestone application. Two acidic soils (pH 4.25 and 4.48) were studied, unlimed or limed to pH 6.5 before cropping. The PLA and KP were applied at 0, 39, and 78 kg P ha(-1), after which wheat was grown. Limestone significantly increased wheat yield, but the P sources without limestone did not. The two P sources were not significantly different as P fertilizer. At the 78 kg P ha(-1) rate, wheat shoot-P concentrations were 1.10 and 1.12 g kg(-1) for the PLA treatment compared with 0.90 and 0.89 g kg(-1) for KP in the nonlimed and limed soils, respectively. Trace element concentrations in wheat shoots from the PLA treatment were less than or equal to KP and the control. The low levels of water-soluble P and metals in the soils and the low metal concentrations in wheat suggest that PLA is an effective P fertilizer. Further studies are needed to determine the optimum application rate of PLA as a P fertilizer.

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