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Epifluorescence microscopy and image analysis of high‐level polycyclic aromatic hydrocarbon contamination in soils
Author(s) -
Roper J. Chadwick,
Brown Denise M.,
Sullivan Michelle A.,
Schoonhoven Robert,
Swenberg James A.,
Pfaender Frederic K.
Publication year - 2006
Publication title -
environmental toxicology and chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.1
H-Index - 171
eISSN - 1552-8618
pISSN - 0730-7268
DOI - 10.1897/06-147r.1
Subject(s) - fluoranthene , pyrene , environmental chemistry , anthracene , chemistry , contamination , perylene , phenanthrene , polycyclic aromatic hydrocarbon , soil water , chrysene , environmental science , soil science , photochemistry , organic chemistry , ecology , molecule , biology
Interactions between polycyclic aromatic hydrocarbons (PAHs) and soil are an important determinant of their chemical availability and transport. Laboratory examination of microscale PAH–soil interaction is limited by the availability of methods for particle‐scale observation. Inverted epifluorescence microscopy, combined with digital photography and computer image analysis, was evaluated for specificity and linearity using dissolved PAHs. A pyrene filter (excitation wavelength, 360–400 nm; emission wavelength, 450–520 nm) gave nonspecific PAH fluorescence, and bias for fluoranthene, benzo[ b ]fluoranthene, benzo[ g, h, i ]perylene, and benz[ a ]anthracene was quantified in comparison to that for pyrene. Concentrations ranging from 1 to 10 mM for anthracene, fluoranthene, and pyrene and from 1 to 50 mM for naphthalene produced a linear response with low interpixel variability. Liquid‐phase analyses validated use of the technique for the descriptive analysis of PAH distribution in solid samples, but liquid‐phase calibration was not quantitative for spiked or field‐contaminated soils. The mean luminance for three field soils was proportional to the values predicted from their chemically measured concentrations and to values from spiked, aged, uncontaminated materials. Image analysis of laboratory‐ and field‐contaminated samples determined the area distribution of fluorescent intensity and the size of fluorescent areas exceeding a threshold luminance. These qualitative descriptions of the microscale spatial distribution of PAH contamination are presented as potential endpoints for future research on biogeochemical interactions in heavily contaminated solids.