School of Environment, Beijing Normal University, State Key Laboratory of Water Environment Simulation, Beijing 100875, China.
Chemosphere. 2013 Feb;90(5):1589-96. doi: 10.1016/j.chemosphere.2012.08.026. Epub 2012 Sep 8.
Perfluoroalkyl acids (PFAs), one kind of emerging contaminants, have attracted great attentions in recent years. However, the study about their bioaccumulation mechanism remains scarce. In this research, the bioaccumulation of six kinds of PFAs in water flea Daphnia magna was studied. The uptake rates of PFAs in D. magna ranged from 178 to 1338 L kg(-1) d(-1), and they increased with increasing perfluoroalkyl chain length; the elimination rates ranged from 0.98 to 2.82 d(-1). The bioaccumulation factors (BAFs) of PFAs ranged from 91 to 380 L kg(-1) in wet weight after 25 d exposure; they increased with increasing perfluoroalkyl chain length and had a significant positive correlation with the n-octanol/water partition coefficients (logK(ow)) of PFAs (p<0.05). This indicated that the hydrophobicity of PFAs plays an important role in their bioaccumulation. The BAFs almost kept constant when the PFA concentrations in aqueous phase increased from 1 to 10 μg L(-1). Scenedesmus subspicatus, as the food of D. magna, did not significantly affect the bioaccumulation of PFAs by D. magna. Furthermore, the body burden of PFAs in the dead D. magna was 1.08-2.52 times higher than that in the living ones, inferring that the body surface sorption is a main uptake route of PFAs in D. magna. This study suggested that the bioaccumulation of PFAs in D. magna is mainly controlled by their partition between organisms and water; further research should be conducted to study the intrinsic mechanisms, especially the roles of protein and lipid in organisms.
全氟烷基酸（PFAs）作为一种新兴的污染物，近年来受到了广泛关注。然而，其生物累积机制的研究仍然较少。本研究考察了六种 PFAs 在水蚤（Daphnia magna）体内的生物累积情况。PFAs 在水蚤体内的吸收速率范围为 178-1338 L kg(-1) d(-1)，随全氟烷基链长的增加而增加；消除速率范围为 0.98-2.82 d(-1)。暴露 25 d 后，PFAs 在水蚤湿重中的生物累积因子（BAFs）范围为 91-380 L kg(-1)；随全氟烷基链长的增加而增加，与 PFAs 的辛醇/水分配系数（logK(ow)）呈显著正相关（p<0.05）。这表明 PFAs 的疏水性在其生物累积中起着重要作用。当水相中 PFA 浓度从 1 增加到 10 μg L(-1)时，BAFs 几乎保持不变。作为水蚤食物的斜生栅藻（Scenedesmus subspicatus）对 PFAs 在水蚤体内的生物累积没有显著影响。此外，死亡水蚤体内 PFAs 的体负载量比活水蚤高 1.08-2.52 倍，这表明水蚤通过体表吸附是 PFAs 的主要吸收途径。本研究表明，PFAs 在水蚤体内的生物累积主要受其在生物和水中分配的控制；应进一步研究内在机制，特别是生物体内蛋白质和脂质的作用。
