Evaluation of lipid peroxidation as a toxicity bioassay for plants exposedto copper

Agricultural soils may contain toxic levels of copper (Cu) due to sewage sl udge spreading or industrial pollution but chemical analyses may not be rep resentative of Cu bioavailability, defined as the soil Cu fraction that pla nts can actually absorb (i.e. Cu fraction which is not strongly adsorbed to soil components). Lipid peroxidation caused by Cu in plants was investigat ed as a relevant bioassay of toxicity. Seven-day-old rapeseed plantlets wer e grown on Cu-supplemented medium in controlled conditions. Lipid-peroxidat ion was assessed by measuring: (1) the 2-thiobarbituric acid (TBA)-reactive substances; (2) the hydroperoxy acids by HPLC analysis; and (3) the alkane outputs by gas chromatography. We first verified the correlation between t he results obtained by each method and then discussed their advantages and disadvantages within the context of a bioassay, showing that the volatile a lkane output measurement is the most precise and easy to perform method for this purpose. (C) 2000 Elsevier Science Ltd. All rights reserved.