Environmental Dispersion and Distribution of Dioxins and DL-PCBs from Agricultural Fields

多氯二苯并对二恶英和二苯并呋喃(PCDD/DFS)和类二恶英的多氯联苯(DL-PCbs)在环境中普遍存在并持续存在，并通过食物链在生物体中放大。这些化合物最终会在人体内积累。众所周知，其中一些化合物对生物体具有极强的毒性。在日本，被八氯二苯并对二恶英(OCDD)污染的五氯苯酚和2，4，6-三氯苯基-4-硝基苯醚(CNP)和1，3，6，8-和1，3，7，9-四氯二苯并-对二恶英(TCDDS)分别作为除草剂应用于农业领域。因此，有必要评估它们在农田中的分散情况以及它们在环境基质中的存在情况。农田土壤中的PCDD/DFS是通过稻作径流进入河流的。据估计，二恶英/二恶英主要存在于直径小于5μm的土壤颗粒中。然后是吸附在…上的二恶英/二恶英更多的土壤颗粒沉积到河流和海岸的底层沉积物中。为了评价蔬菜中的二恶英污染状况，对3种蔬菜(43个个体)进行了PCDD/DFS和DL-PCbs的同源分析。样品中二恶英的总浓度为0.19pg/g湿重至16pg/g湿重，毒性当量为0.002~0.071 pgTEQ/g湿重。1，3，6，8-和1，3，7，9-二恶英是蔬菜样品中二恶英总浓度的主要贡献者。这意味着蔬菜在生长过程中一定会受到农田中这些化合物的污染。在黄瓜样品中发现了较高浓度的二恶英。淡水和沿海鱼类中PCDD/DFS和DL-PCbs的分析结果表明，在所调查的所有样品中都检测到了这些化合物。作为稻田除草剂的CNP和PCP中的杂质被认为是鱼类样品的PCDD/DFS来源。而日本鱼样品中的1，3，6，8-和1，3，7，9-TCDDS和OCDD含量没有日本鱼样品高。对从日本采集的10种野生鸟类中的二恶英和二氯联苯进行了分析。结果表明，它们的浓度和同系物/异构体分布具有物种特异性，具有独特的生境和摄食习性。似乎1，3，6，8-和1，3，7，9-TCDDS等农药的杂质在鸟类体内可以被降解，尽管它们是通过鱼类等食物摄入的。对从不同年龄的人身上采集的日本人血液样本进行了多氯二苯并二恶英/二苯并呋喃和二氯二苯并二恶英的分析。以脂肪重量计算，PCDDs、PCDFs和DL-PCbs的浓度范围分别为58-930、7.4-37和3,100-23,000pg/g。在脂类重量的基础上，TEQ水平计算为7.0-46pg/g。人血中1，3，6，8-和1，3，7，9-TCDDS含量均低于检出限。统计分析表明，总TEQ水平的增加与年龄的增加之间存在相关性。60岁的人的TEQ水平大约是20岁的人的两倍。通过这些结果，能够解释二恶英的可分布性质，这些二恶英曾作为除草剂的杂质应用于农业领域。较少

Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/DFs) and dioxin-like polychlorinated biphenyls (DL-PCBs) are ubiquitous and persistent in the environment and magnify in organisms through the food web. These compounds finally accumulate in humans. It is well known that some of these compounds are extremely toxic to organisms. In Japan, specific congeners and isomers were applied to agricultural fields as herbicides, i.e. pentachlorophenol and 2,4,6-trichiorophenyl 4-nitrophenylether (CNP), contaminated with octachlorinated dibenzo-p-dioxin(OCDD), and 1,3,6,8- and 1,3,7,9-tetrachlorinated dibenzo-p-dioxins(TCDDs), respectively. Consequently, it is necessarily to evaluate their dispersion from agricultural fields and their presence in environmental matrices. PCDD/DFs in soils of agricultural fields were entered into river through run off caused by rice farming. It is estimated that PCDD/DFs mainly presented in soil particles less than 5μm diameter. Then PCDD/DFs that adsorbed on … More the soil particles deposited to river and coastal bottom sediments. To evaluate dioxin contamination in vegetable, congener analyses of PCDD/DFs and DL-PCBs were performed on three kinds of vegetables (43 individuals). The total dioxin concentrations and toxic equivalent quantity (TEQ) levels in samples ranged from 0.19 to 16 pg/g wet weight and 0.002 to 0.071 pg TEQ/g wet weight, respectively. 1,3,6,8- and 1,3,7,9-TCDDs were main contributors of total dioxin concentrations detected in the vegetable samples. It imply that vegetables must be contaminated by these compounds in agricultural fields during growing. A relatively high concentration of dioxins was found in cucumber samples. The analytical results of PCDD/DFs and DL-PCBs in freshwater and coastal fishes show that these compounds detected in all samples investigated. Impurities of CNP and PCP as herbicides for paddy field were thought as PCDD/DFs sources of fish samples. Whereas Japanese fish samples, 1,3,6,8- and 1,3,7,9-TCDDs and OCDD levels in Chinese fish samples were not so high as the Japanese samples. Dioxins and DL-PCBs in ten species of wild birds collected from Japan were analyzed. The results revealed that the concentrations and homologue / isomer profiles were species-specific, featuring with their unique habitats and feeding habits. It seems to be that the impurities of pesticides such as 1,3,6,8- and 1,3,7,9-TCDDs could be degraded in the birds although intake through their foods such as fish. Japanese human blood samples collected from differently-aged individuals have been analyzed for PCDD/DFs and DL-PCBs. The concentration ranges of PCDDs, PCDFs and DL-PCBs were 58-930, 7.4-37 and 3,100-23,000pg/g, respectively, on a lipid weight basis. TEQ levels were calculated to be 7.0-46pg/g on a lipid weight basis. The levels of 1,3,6,8- and 1,3,7,9-TCDDs in human blood samples were less than detection limit. Statistical analysis indicated a correlation between an increased total TEQ level and increased age. TEQ level of a person aged 60 years is about twice times higher than a person aged 20 years. By these results it is able to make sense out of what had appeared the distributable properties of dioxins which were ever applied as impurities of herbicides to agricultural fields. Less