Bioaccumulation of organochlorine compounds in earthworms

Abstract

Bioaccumulation of chlorophenolic wood preservatives 2,3,4,6-tetrachlorophenol (2346-TeCP) and pentachlorophenol (PeCP) and their metabolites in earthworms were studied in the laboratory, and by taking worm samples from the contaminated soil of a sawmill which was abandoned 28 yr ago. In two laboratory experiments 2346-TeCP (containing PeCP as impurity) was added into the soil, and samples were taken at certain intervals both from the soil and the earthworms ( Lumbricus rubellus in experiment 1 and Aporrectodea caliginosa tuberculata in experiment 2). Considerable amounts of chlorophenols were found in field samples. Soil concentrations ranged from 157 to 338 μg 2346-TeCP g −1 dry soil and from 103 to 140μg PeCP g −1 dry soil. Earthworm concentrations ranged from 270 to 2000 μg 2346-TeCP g −1 fat and from 130 to 1500μg PeCP g −1 fat, respectively. Earthworms also contained chlorinated anisoles (1–20 μg g −1 fat). On the other hand, chlorinated dihydroxybenzenes were not detected in earthworms, while these substances were present in the soil. Concentrations of chlorophenols were higher in A. caliginosa than in Lumbricus spp. In the pot experiments concentrations of chlorophenols in earthworms increased sharply during the experiments, and concentrations as high as 1800 μg g −1 fat were detected after some weeks incubation (in experiment 1, 61 μg chlorophenols g −1 dry soil, and in experiment 2, 154μg chlorophenols g −1 dry soil, was added). The earthworms had no influence on the concentrations of chlorophenols in the soil.