Abstract: Biodegradability of di-n-butyl phthalate (DBP), butylbenzyl
phthalate (BBP), di-ethylhexyl phthalate (DEHP), and di-isononyl phthalate
(DINP) under an anaerobic condition was evaluated using three natural sediment
microcosms obtained from ponds in Osaka, which had not been significantly
polluted by the chemicals. The degradabilities of the four phthalic acid
esters(PAEs)were analyzed by a first-order kinetic model with a lag phase and
ranked as DBP>BBP>>DEHP>DINP. The PAEs with shorter alkyl-chains,
DBP and BBP, were degraded with quite short lag phases near to zero and short
half-lives of a few days. The PAEs with longer alkyl-chains, DEHP and DINP,
were degraded with lag phases of 5–30 d and the quite long half-lives of
a couple of hundred days. Although no data was available on the anaerobic
biodegradability of DINP before this study, it was clarified that DINP can be
degraded with slow degradation rates. The fact that all the three intact
sediments were capable of biodegradation of the PAEs suggests that potential of
anaerobic biodegradation of PAEs is widespread in the aquatic environment.
