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MFO induction in fish by spent cooking liquors from kraft pulp mills
Author(s) -
Hodson Peter V.,
Maj M. K.,
Efler S.,
Burnison B. K.,
van Heiningen A. R. P.,
Girard R.,
Carey J. H.
Publication year - 1997
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 - 10.1002/etc.5620160510
Subject(s) - softwood , black liquor , kraft process , pulp and paper industry , kraft paper , chemistry , hardwood , pulp (tooth) , black spruce , lignin , effluent , waste management , botany , organic chemistry , biology , medicine , ecology , pathology , taiga , engineering
Within bleached kraft mills, the main sources of compounds inducing the mixed function oxygenase (MFO) activities of fish are waste cooking liquor, black liquor, and effluents from the first stages of the bleaching process. We measured the potency for MFO induction in rainbow trout ( Oncorhynchus mykiss ) of black liquors from pulp mills using kraft pulping and either softwood or hardwood furnish. Concentrations causing induction ranged from 0.0032 to 0.2%(v/v), and below critical thresholds, concentration‐response relationships were linear. Above threshold concentrations, activity declined, and lethality occurred at concentrations greater than 0.1% (v/v) black liquor during 4‐d exposures. Hardwood pulping generated black liquor that was less potent than that from softwood, but much of the difference was due to a higher water content; hardwood black liquor was more dilute as indicated by normalizing results to dissolved organic carbon. Compounds inducing MFO activity may be natural wood extractives associated with wood resins, or compounds created by the digestion of lignin. A high potency of black liquor from alcohol pulping supports the hypothesis of a natural compound because alcohol extraction does not chemically alter lignin to the same extent as kraft pulping; inducing compounds can also be extracted from wood chips with dichloromethane. The high potency of black liquor compared to bleaching or extraction‐stage effluents suggests that control of black liquor losses may be very important in limiting exposure of fish to inducing compounds.