Effects of fluoranthene on the growth, bioavailability and anti-oxidant system of Eisenia fetida during the ageing process

Studies were conducted to assess the effects of certain concentrations of fluoranthene on the growth, bioavailability, and anti-oxidant system of Eisenia fetida during the ageing process. The concentration of fluoranthene in the soil decreased rapidly during the first: 25 days (27.0% decrease) followed by a slower decrease in the next 90 days (11.2% decrease). The increase in the weight ratio (WR) was initially rapid and then slowed with ageing in a manner consistent with the rate of decrease in fluoranthene concentration. The bioconcentration factor (BCF) and the concentration of fluoranthene in the earthworms' epidermis and intestines increased prior to 25 days but decreased thereafter. This result confirmed that the bioavailability of fluoranthene decreases as time increases, except when increased toxicity caused the earthworms to die at the beginning of the experiment. The fluoranthene concentration and the BCF in earthworms' intestines were higher than those in the epidermis throughout the whole experiment, which suggested that earthworms accumulate fluoranthene mainly by ingesting it with soil particles rather than by penetrating it through their epidermis. The effects of fluoranthene on anti-oxidative enzyme activity (superoxide dismutase, SOD; catalase, CAT; guaiacol peroxidase. POD and polyphenol oxidase. PPO) and malondialdehyde (MDA) content in earthworms were also investigated. The activities of SOD, POD, and PPO and the content of MDA decreased gradually, but the activity of CAT decreased initially and then increased thereafter. The WR, POD, and PPO sensitivities of the earthworms were closely related to the decrease in fluoranthene concentration, while the sensitivity to SOD lagged behind. (C) 2011 Elsevier Masson SAS. All rights reserved.