State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Xianlin Avenue 163, 210023 Nanjing, China.
Institute for Ecopreneurship, School of Life Sciences, University of Applied Sciences and Arts Northwestern Switzerland, Gründenstrasse 40, 4132 Muttenz, Switzerland.
Sci Total Environ. 2017 Dec 1;599-600:332-339. doi: 10.1016/j.scitotenv.2017.04.243. Epub 2017 May 4.
The nature and stability of bound residues (BRs) derived from the widely used brominated flame retardant tetrabromobisphenol A (TBBPA) in fine-textured soil is unknown. We incubated C-labeled TBBPA in silty clay rice paddy soil for 93days under oxic conditions. TBBPA dissipated with a first-order kinetic constant k of 0.0474±0.0017day (t 14.6±0.3days) and mineralized with a k of 0.0011±0.00002day. At the end of the incubation, four metabolites, including two methylation products (TBBPA monomethyl and dimethyl ether), accounted for 7.9±0.1% of the initial TBBPA. The BRs continuously increased in amount to a maximum of 80.1±3.6%. About 86.3±0.9% of the BRs localized in the humin fraction and 55.9±1.5% was hydrolyzable with strong alkali (SAH-BRs), which represents reversible BRs. Together with results previously reported for coarse-textured soil, these results indicate that the absolute amounts of both BRs and SAH-BRs of TBBPA as well as the relative contribution of SAH-BRs to total BRs in fine-textured soil are markedly higher than in coarse-textured soil. When BRs-containing soil was incubated with fresh soil for 231days, 9.2±0.3% was mineralized (k 0.00047±0.00002day) and SAH-BRs decreased to 34.1±1.1%, accompanied by transformation into other BR forms. These indicate that BRs are bioavailable in the soil. Amendment with rice root exudates did not effectively affect the mineralization, release, and distribution of BRs, suggesting that bioavailability of BRs but not microbial activity limits the degradation of BRs in the silty clay soil. This study provides first insights into the nature and stability of TBBPA-derived BRs in fine-textured soil under oxic conditions and indicates the significant role of reversible BRs in the environmental risk of TBBPA.
bound residues (BRs) 衍生自广泛使用的溴化阻燃剂四溴双酚 A（TBBPA），但其在细质地土壤中的性质和稳定性尚不清楚。我们在有氧条件下，将 C 标记的 TBBPA 孵育在粉质粘壤土稻田土壤中 93 天。TBBPA 以 0.0474±0.0017 天的一级动力学常数 k 消散（t 14.6±0.3 天），并以 0.0011±0.00002 天的 k 矿化。在孵育结束时，四种代谢物，包括两种甲基化产物（TBBPA 单甲基和二甲基醚），占初始 TBBPA 的 7.9±0.1%。BRs 的数量不断增加，最高达到 80.1±3.6%。约 86.3±0.9%的 BRs 定位于腐殖质部分，55.9±1.5%可被强碱（SAH-BRs）水解，这代表了可逆 BRs。结合先前报道的粗质地土壤的结果，这些结果表明，TBBPA 的 BRs 和 SAH-BRs 的绝对数量以及 SAH-BRs 占总 BRs 的相对比例在细质地土壤中明显高于粗质地土壤。当含 BRs 的土壤与新鲜土壤一起孵育 231 天时，9.2±0.3%被矿化（k 0.00047±0.00002 天），SAH-BRs 减少到 34.1±1.1%，同时转化为其他 BR 形式。这表明 BRs 在土壤中是生物可利用的。用水稻根分泌物进行改良并没有有效地影响 BRs 的矿化、释放和分布，这表明 BRs 的生物利用度而不是微生物活性限制了 BRs 在粉质粘壤土中的降解。本研究首次深入了解了有氧条件下细质地土壤中 TBBPA 衍生的 BRs 的性质和稳定性，并表明了可逆 BRs 在 TBBPA 环境风险中的重要作用。
