Abstract:Uptake of aged and current residual p,p'-DDT and its metabo lites DDD,DDE,DDMU and DDMS (DDX for short) in soil by paddy rice (Oryza sativa) was researched with pot expermients in greenhouse.The total growth period of rice was 126 days.Resu lts reveal that recently applied DDT degraded much faster than aged DDT residues in paddy soil and its dominating metabolite formed was DDD.Subordinate metabolites DDMS and DDMU were identified by GC/MS.Paddyrice could absorb both forms,the aged and current DDX residues from soil,and tran sport them to aerial compartments; so that the bioavailability of lower leveled aged DDX shouldnt be underestimate.Despite a high concentration of DDD (900 ng g-1) absorbed by paddy roots in soil treated with DDT recently,the tran smission of DDX from root to edible part of the plant was limited.Concentration of DDX in roots is not a good indicator of the status of DDX in brown rice.It was worthy noting that the root concentration factors (RCFs) for DDMS or DDMU were about 3 times as high as for DDD or DDE.The data illuminated more prominent bioava ilability of DDMS and DDMU than their maternal compounds.Regardless of the contents and forms of DDX residues in soil,similar contents of DDX were observed in brown rice from different treatments.Distribution of DDX changed obviously with DDX transporting to edible part from root.The reasons are: first,motilities of DDT and its metab olites from root to aerial are different,and second,farther degradation of DDX would occur in rice plant.