全氟辛烷磺酰胺在小麦和蚯蚓中的富集与转化

研究了不同培养介质和培养方式下全氟辛烷磺酰胺（PFOSA）在小麦、蚯蚓体内的生物富集和转化.结果表明：小麦根系可以从培养介质中吸收PFOSA并向上转运至茎叶.土壤中PFOSA生物有效性受总有机碳（TOC）的影响显著，高TOC含量土壤中PFOSA的生物有效性降低，导致其在小麦和蚯蚓中的生物富集因子分别由（61.24±8.42）和（21347.91±208.86）降至（5.61±0.23）和（1404.92±108.21）.PFOSA在小麦的根和茎叶以及蚯蚓中都可以转化为PFOS，但在蚯蚓中的转化率（（3.87±1.71）%）显著低于小麦（（26.39±3.02）%）.小麦根中PFOS的支链异构体（br-PFOS）比例在低、高TOC含量时分别为（14.8±2.0）%、（66.1±26.2）%，低于茎叶（分别为（63.0±21.3）%、（85.2±2.4）%）），可能是由于根部转化生成的br-PFOS更容易向茎叶转运.小麦特别是小麦茎叶中的br-PFOS比例（（85.2±2.4）%）显著高于蚯蚓（（16.5±4.0）%）.小麦的存在可以提高土壤中PFOSA的生物有效性，从而促进蚯蚓对PFOSA的富集，但对其转化影响不大.本文为小麦和蚯蚓中PFOSA的富集和转化提供了证据，有助于探索环境中PFOS的间接来源.

Bioaccumulation and biotransformation of perfluorooctane sulfonamide in wheat and earthworms

The bioaccumulation and biotransformation of perfluorooctane sulfonamide (PFOSA) in wheat and earthworms was investigated in different culture media by different culture methods. The results indicated that PFOSA was effectively absorbed by wheat roots from the culture media and translocated from roots to shoots. The bioavailability of PFOSA in soil was significantly affected by the soil total organic carbon (TOC) content. The bioavailability of PFOSA in the soil with higher TOC content was reduced, resulting in the bioaccumulation factors in wheat and earthworms decreased from (61.24±8.42) and (21347.91±208.86) to (5.61±0.23) and (1404.92±108.21), respectively. PFOSA could be transformed into PFOS in the earthworms as well as in the roots and shoots of wheat, but the transformation rate of PFOSA in the earthworms ((3.87±1.71)%) was significantly lower than that in the wheat ((26.39±3.02)%). The ratio of branched PFOS isomers (br-PFOS) in the wheat roots was (14.8±2.0)% and (66.1±26.2)% at low and high TOC content, respectively, lower than those in the shoots ((63.0±21.3)% and (85.2±2.4)%), respectively), which might be because it was easier to translocate br-PFOS formed in roots to shoots. The ratio of br-PFOS in wheat, especially in wheat shoots ((85.2±2.4)%), was significantly higher than that in earthworms ((16.5±4.0)%). The presence of wheat enhanced the bioavailability of PFOSA in the soil, thereby promoted the accumulation of PFOSA in earthworms, but had little effect on the transformation of PFOSA. The results provided evidence for the bioaccumulation and biotransformation of PFOSA in wheat and earthworms, and were helpful to explore the indirect sources of PFOS in the environment.