FLUORENE

At concentrations of 5 and 10 mg/L, biodegradation yields at the end of 4 wk of incubation were 77 and 45%, respectively (Tabak et al., 1981). Grifoll et al. (1995) investigated the degradation of fluorene by Pseudomonas cepacia F297 strain. Fluorene degraded via reductive dioxygenation at C-3 and C-4 and a hydratase-aldolase reaction yielding the 3,4-dihydroxyfluorene and 2-formyl-1-indanone, respectively. The latter compound degraded forming 1-indanone. Fluorene was oxidized by salicylate-induced cells of Pseudomonas sp. strain 9816/11 and isopropyl-β-D-thiogalactopyranoside-induced cells of Escherichia coli JM109(DE3) (pDTG141) to (+)-(3S,4R)-cis-3,4-dihydroxy-3,4-dihydrofluorene (80 to 90% yield) and 9-fluorenol (10% yield) (Resnick and Gibson, 1996). Products identified for the metabolism of fluorine by Arthrobacter sp. strain F101 were 9fluorenone, 5-hydroxy-9-fluorenone, 3-hydroxy-1-indanone, 1-indanone, 2-indanone, 3-(2hydroxyphenyl) propionate and a compound tentatively identified as a formyl indanone (Casellas et al., 1997). Photolytic. Fluorene reacts with photochemically produced OH radicals in the atmosphere. The atmospheric half-life was estimated to range from 6.81 to 68.1 h (Atkinson, 1987). Behymer and Hites (1985) determined the effect of different substrates on the rate of photooxidation of fluorene (25 µg/g substrate) using a rotary photoreactor. The photolytic half-lives of fluorene using silica gel, alumina, and fly ash were 110, 62, and 37 h, respectively. Gas-phase reaction rate constants for OH radicals, NO3 radicals, and ozone at 24 °C were 1.6 x 10-11, 3.5 x 10-15, and <2 x 10-19 in cm3/molecule⋅sec, respectively (Kwok et al., 1997). Chemical/Physical. Oxidation by ozone to fluorenone has been reported (Nikolaou, 1984). Chlorination of fluorene in polluted humus poor lake water gave a chlorinated derivative tentatively identified as 2-chlorofluorene (Johnsen et al., 1989). This compound was also identified as a chlorination product of fluorene at low pH (<4) (Oyler et al., 1983). It was suggested that the chlorination of fluorene in tap water accounted for the presence of chlorofluorene (Shiraishi et al., 1985). At influent concentrations of 1.0, 0.1, 0.01, and 0.001 mg/L, the GAC adsorption capacities were 330, 170, 89, and 46 mg/g, respectively (Dobbs and Cohen, 1980). Exposure limits: Potential occupational carcinogen. No individual standards have been set; however, as a constituent in coal tar pitch volatiles and asphalt products, the following exposure limits have been established (mg/m3): NIOSH REL: TWA 0.1 (cyclohexane-extractable fraction), IDLH 80; OSHA PEL: TWA 0.2 (benzene-soluble fraction); ACGIH TLV: TWA 0.2 (benzene solubles). Toxicity: EC10 (21-d) for Folsomia fimetaria 7.7 mg/kg (Sverdrup et al., 2002). EC50 (21-d) for Folsomia fimetaria 14 mg/kg (Sverdrup et al., 2002). LC50 (21-d) for Folsomia fimetaria 39 mg/kg (Sverdrup et al., 2002). EC50 (48-h) for Daphnia magna 430 µg/L, Chironomus plumosus 2.35 mg/L (Mayer and Ellersieck, 1986), Daphnia pulex 212 µg/L (Smith et al., 1988). IC50 (48-h) for Daphnia magna 430 µg/L (Finger et al., 1985). LC50 (contact) for earthworm (Eisenia fetida) 171 µg/cm2 (Neuhauser et al., 1985). LC50 (96-h) for juvenile rainbow trout 820 µg/L (Finger et al., 1985). Drinking water standard: No MCLGs or MCLs have been proposed, however, a DWEL of 1 mg/L was recommended (U.S. EPA, 2000). Source: Fluorene was detected in groundwater beneath a former coal gasification plant in Seattle, WA at a concentration of 140 µg/L (ASTR, 1995). Present in diesel fuel and corresponding

respectively (Lee et al., 1992). Schauer et al. (1999) reported fluorene in diesel fuel at a concentration of 52 g/g and in a diesel-powered medium-duty truck exhaust at an emission rate of 34.6 g/km. Diesel fuel obtained from a service station in Schlieren, Switzerland contained fluorene at an estimated concentration of 170 mg/L (Schluep et al., 2001). Based on laboratory analysis of 7 coal tar samples, fluorene concentrations ranged from 1,100 to 12,000 ppm (EPRI, 1990). Lao et al. (1975) reported a fluorene concentration of 27.39 g/kg in a coal tar sample. Detected in 1-yr aged coal tar film and bulk coal tar at an identical concentration of 4,400 mg/kg (Nelson et al., 1996). A high-temperature coal tar contained fluorene at an average concentration of 0.64 wt % (McNeil, 1983). Identified in high-temperature coal tar pitches at concentrations ranging from 800 to 4,000 mg/kg (Arrendale and Rogers, 1981). Lee et al. (1992a) equilibrated 8 coal tars with distilled water at 25 °C. The maximum concentration of fluorene observed in the aqueous phase was 0.3 mg/L. Fluorene was detected in asphalt fumes at an average concentration of 34.95 ng/m3 (Wang et al., 2001). Nine commercially available creosote samples contained fluorene at concentrations ranging from 19,000 to 73,000 mg/kg (Kohler et al., 2000). Thomas and Delfino (1991) equilibrated contaminant-free groundwater collected from Gainesville, FL with individual fractions of three individual petroleum products at 24-25 °C for 24 h. The aqueous phase was analyzed for organic compounds via U.S. EPA approved test method 625. Average fluorene concentrations reported in water-soluble fractions of unleaded gasoline, kerosene, and diesel fuel were 1, 3, and 10 µg/L, respectively. Fluorene was detected in soot generated from underventilated combustion of natural gas doped with toluene (3 mole %) (Tolocka and Miller, 1995). Schauer et al. (2001) measured organic compound emission rates for volatile organic compounds, gas-phase semi-volatile organic compounds, and particle-phase organic compounds from the residential (fireplace) combustion of pine, oak, and eucalyptus. The gas-phase emission rates of fluorene were 4.44 mg/kg of pine burned, 3.83 mg/kg of oak burned, and 2.613 mg/kg of eucalyptus burned. California Phase II reformulated gasoline contained fluorene at a concentration of 4.35 mg/kg. Gas-phase tailpipe emission rates from gasoline-powered automobiles with and without catalytic converters were 9.72 and 358 µg/km, respectively (Schauer et al., 2002). Under atmospheric conditions, a low rank coal (0.5-1 mm particle size) from Spain was burned in a fluidized bed reactor at seven different temperatures (50 °C increments), beginning at 650 °C. The combustion experiment was also conducted at different amounts of excess oxygen (5 to 40%) and different flow rates (700 to 1,100 L/h). At 20% excess oxygen and a flow rate of 860 L/h, the amount of fluorine emitted ranged from 850.7 ng/kg at 950 °C to 3,632.8 ng/kg at 750 °C. The greatest amount of PAHs emitted were observed at 750 °C (Mastral et al., 1999). In one study, fluorene comprised about 7.6% of polyaromatic hydrocarbons in creosote (Grifoll et al., 1995). Identified as an impurity in commcerially available acenaphthene (Marciniak, 2002). Typical concentration of fluorene in a heavy pyrolysis oil is 1.6 wt % (Chevron Phillips, May 2003). Uses: Chemical intermediate in numerous applications and in the formation of polyradicals for resins; insecticides and dyestuffs. Derived from industrial and experimental coal gasification operations where the maximum concentrations detected in gas, liquid, and coal tar streams were 9.1, 0.057, and 8.0 mg/m3, respectively (Cleland, 1981).