Hou Xingwang, Zhang Haiyan, Li Yanlin, Yu Miao, Liu Jiyan, Jiang Guibin
State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, P.O. Box 2871, Beijing 100085, China.
Environ Sci Process Impacts. 2017 Oct 18;19(10):1327-1335. doi: 10.1039/c7em00304h.
Hexachlorobutadiene (HCBD) has been listed as a persistent organic pollutant (POP) in the Stockholm Convention, and is now drawing more and more research interest. However, the understanding of its bioaccumulation, especially in plants, is still very limited. In this work, the behavior of HCBD in aqueous solution and pumpkin seedlings was studied through in-lab hydroponic exposure experiments. It was found that 69% of HCBD volatilized from water to the atmosphere after one day of exposure, and only 1% remained in the solution after four days. This high volatility might be the main cause of the low HCBD levels in aqueous environments. Although a great amount of HCBD volatilized into the atmosphere, only a small proportion of airborne HCBD was captured by the leaves and stems of the blank pumpkin seedling controls. The translocation of HCBD from the leaves to the bottom roots, as well as its release from the roots into the water, was detected. For the exposure groups, the pumpkin seedlings absorbed HCBD from both the hydroponic solution and the air via the roots and leaves, respectively. The concentration of HCBD in the exposed pumpkin roots linearly increased with the continuous addition of HCBD into the exposure system. Upward translocation from the roots to the leaves and downward translocation from the leaves to the roots existed simultaneously in the exposed pumpkin seedlings. However, the concentrations of HCBD in the leaves, stems and roots in the exposure group were much higher than those of the blank plant controls, suggesting little contribution from the airborne HCBD in the hydroponically exposed pumpkin seedlings. The lipid content did not show obvious effects on the bioaccumulation and biodistribution of HCBD in the pumpkin seedlings, indicating that the translocation of HCBD within the pumpkin seedlings might be an active process. This study provided new findings on the environmental behavior of HCBD, which will be helpful for understanding the exposure risks.
六氯丁二烯（HCBD）已被列入《斯德哥尔摩公约》中的持久性有机污染物（POP）名单，目前正吸引着越来越多的研究关注。然而，人们对其生物累积情况，尤其是在植物中的生物累积情况的了解仍然非常有限。在这项研究中，通过室内水培暴露实验研究了六氯丁二烯在水溶液和南瓜幼苗中的行为。研究发现，暴露一天后，69%的六氯丁二烯从水中挥发到大气中，四天后溶液中仅残留1%。这种高挥发性可能是水环境中六氯丁二烯含量低的主要原因。尽管大量的六氯丁二烯挥发到大气中，但空白南瓜幼苗对照组的叶片和茎干仅捕获了一小部分空气中的六氯丁二烯。检测到六氯丁二烯从叶片向底部根系的转运，以及从根系向水中的释放。对于暴露组，南瓜幼苗分别通过根系和叶片从水培溶液和空气中吸收六氯丁二烯。随着向暴露系统中持续添加六氯丁二烯，暴露的南瓜根系中六氯丁二烯的浓度呈线性增加。在暴露的南瓜幼苗中，六氯丁二烯从根系向上转运到叶片和从叶片向下转运到根系的情况同时存在。然而，暴露组叶片、茎干和根系中的六氯丁二烯浓度远高于空白植物对照组，这表明水培暴露的南瓜幼苗中，空气中的六氯丁二烯对其生物累积的贡献很小。脂质含量对六氯丁二烯在南瓜幼苗中的生物累积和生物分布没有明显影响，这表明六氯丁二烯在南瓜幼苗内的转运可能是一个主动过程。本研究为六氯丁二烯的环境行为提供了新的发现，这将有助于了解其暴露风险。
