title: Determination of nickel species in stack emissions from eight residual oil-fired utility steam-generating units.
abstract: XAFS spectroscopy has been used to determine the Ni species in particulate matter collected on quartz thimble filters in the stacks of eight residual (No. 6 fuel) oil-burning electric utility steam-generating units. Proper speciation of nickel in emitted particulate matter is necessary to correctly anticipate potential health risks. Analysis of the spectroscopic data using least-squares linear combination methods and a newly developed method specific for small quantities of Ni sulfide compounds in such emissions show that potentially carcinogenic Ni sulfide compounds are absent within the detection limits of the method (≤ 3% of the total Ni) in the particulate matter samples investigated. In addition to the major nickel sulfate phase (NiSO(4)·6H(2)O), lesser amounts of (Ni,Mg)O and/or NiFe(2)O(4) were also identified in most emission samples. On the basis of the results from these emission characterization studies, the appropriateness of the U.S. Environmental Protection Agency's assumption that the Ni compound mixture emitted from residual oil-fired power plants is 50% as carcinogenic as nickel subsulfide (Ni(3)S(2)) should be re-evaluated.
authors.affiliation: Department of Chemical and Materials Engineering, University of Kentucky, 103 S. J. Whalen Building, 533 S. Limestone Street, Lexington, Kentucky 40506-0043, USA. Frank.Huggins@uky.edu
authors.forename: Frank E
authors.initials: FE
authors.lastname: Huggins
authors.forename: Kevin C
authors.initials: KC
authors.lastname: Galbreath
authors.forename: Kurt E
authors.initials: KE
authors.lastname: Eylands
authors.forename: Lisa L
authors.initials: LL
authors.lastname: Van Loon
authors.forename: Jeremy A
authors.initials: JA
authors.lastname: Olson
authors.forename: Edward J
authors.initials: EJ
authors.lastname: Zillioux
authors.forename: Stephen G
authors.initials: SG
authors.lastname: Ward
authors.forename: Paul A
authors.initials: PA
authors.lastname: Lynch
authors.forename: Paul
authors.initials: P
authors.lastname: Chu
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D060729:Coal Ash / Q000032:analysis / Q000737:chemistry*; D004784:Environmental Monitoring / Q000706:statistics & numerical data*; D016018:Least-Squares Analysis; D009532:Nickel / Q000032:analysis* / Q000737:chemistry; D011210:Power Plants; D013227:Steam; D056928:X-Ray Absorption Spectroscopy
chemical_list: D000393:Air Pollutants; D060729:Coal Ash; D013227:Steam; D009532:Nickel; C017557:nickel subsulfide