[en] Organochlorinated pesticide such as Lindane is very persistent in the marine environment. The distribution of sup 14 C-lindane in a simulative mudflat micro-ecosystem; in sea water, sediment and cockle (Anadara granosa) compartments was studied for a period of 10 weeks under aeration. Cockle bioconcentrated 2808.4 Bq/g tissue one day after exposure, which was gradually reduced to 1754.5 Bq/g tissue six days later. Lindane was probably slowly depurated by cockle following its migration to deeper-sediment layer within one week of exposure. Sediment absorption of sup 14 C-lindane was observed in the first and second weeks, reaching 595.4 Bq/g sediment at 15 days after exposure. A steady decline of its concentration was shown between 2-10 weeks of exposure to 216.7 Bq/g sediment possibly due to sediment desorption. The sup 14 C-lindane level in sea water was shown to steeply drop from 53.3 Bq/ml to 24.8 Bq/ml within 2 weeks exposure, followed by a steady decline to 0.47 Bq/ml between 2-10 weeks of exposure. The unaccounted radioactivity could have been lost in the form of volatilized lindane