水稻对土壤中DDT及其系列降解物的吸收  

UPTAKE OF AGED RESIDUAL AND CURRENT-APPLIED DDT AND ITS METABOLITES,DDD,DDMS AND DDMU BY PADDY RICE(ORYZA SATIVA)

作　　者：安琼[1] 董元华[1] 王辉[1] 魏峰[1] 

机构地区：[1]中国科学院南京土壤研究所,南京210008

出　　处：《土壤学报》2008年第4期686-692,共7页Acta Pedologica Sinica

基　　金：国家重点基础研究发展规划项目(2002CB410805)资助

摘　　要：在温室条件下,盆栽种植水稻(Oryza sativa,淹水土壤),设老化态DDT残留和新施入DDT两种处理,生长期126 d。研究结果显示:老化残留DDT在土壤中降解十分缓慢,而新施入DDT在土壤中降解相当迅速,GC/MS鉴定结果表明,降解物除DDD外,还有DDMS和DDMU。尽管土壤中老化残留的降解受到明显抑制,但水稻根系仍可吸收利用并向地上组织传输,因此不可低估老化残留的生物有效性。在新施入DDT的处理中,水稻根系对DDD的吸收量高达900 ng g-1,不过,根系向地上部组织传输DDX的能力极为有限。值得注意的是:水稻根系对土壤中DDMS和DDMU吸收的生物富集因子为DDD或DDE的3倍,表明DDMU和DDMS具有较母体化合物更为突出的作物可吸收利用性。DDX各组分从水稻根系向地上组织传输时,其分布状况发生了明显的变化,引起这种变化的主要原因是作物在吸收和传输DDX时具有一定的选择性,或者DDX在这种吸收和传输过程中发生了进一步的降解。Uptake of aged and current residual p,p′-DDT and its metabolites DDD, DDE, DDMU and DDMS （DDX for short） in soil by paddy rice （Oryza sativa） was researched with pot experiments in greenhouse. The total growth period of rice was 126 days. Results 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. Paddy rice could absorb both forms, the aged and current DDX residues from soil, and transport them to aerial compartments ; so that the bio-availability of lower-leveled aged DDX shouldn＇ t be underestimate. Despite a high concentration of DDD （900 ng g^-1） absorbed by paddy roots in soil treated with DDT recently, the transmission 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 bio-availability 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 metabolites from root to aerial are different, and second, farther degradation of DDX would occur in rice plant.

关 键 词：DDT及其降解物(DDX) 老化残留 新施用残留物 水稻 作物吸收 

分 类 号：X53[环境科学与工程—环境工程]