Kinetics of stereoselective enrichment of Dechlorane Plus in Ulva Pertusa.

Dechlorane Plus (DP) has been detected extensively in both biotic and abiotic matrices, and stereoselective enrichment of Dechlorane Plus isomers has also been observed in organisms. In this laboratory study, Ulva pertusa were firstly exposed to known Dechlorane Plus concentrations for 21d (uptake period), and then transferred to clean seawater for 14d (depuration period) to investigate the kinetics of Dechlorane Plus isomers in U. pertusa. Dechlorane Plus isomers reached steady-state after 21d of exposure. The mean fractional abundance of syn-DP (fsyn) exceeded than that of 0d (0.23±0.02) during uptake, but decreased during depuration. This study is the first to define the kinetics of stereoselective enrichment of Dechlorane Plus isomers in U. pertusa using two-box kinetic model. The uptake rate constants of the syn- and anti-DP were 0.164±0.056d(-1) and 0.083±0.071d(-1), respectively. The depuration rate constants were 0.337±0.057d(-1) (syn-DP) and 0.236±0.095d(-1) (anti-DP), suggesting that syn-DP is eliminated quicker than anti-DP by U. pertusa. These results are consistent with observation of fsyn and stereoselective enrichment of Dechlorane Plus isomers in U. pertusa.