Center for Environmental Science in Saitama, 914 Kamitanadare, Kazo, Saitama 347-0115, Japan.
Center for Environmental Science in Saitama, 914 Kamitanadare, Kazo, Saitama 347-0115, Japan.
Sci Total Environ. 2022 Sep 10;838(Pt 2):155956. doi: 10.1016/j.scitotenv.2022.155956. Epub 2022 May 14.
We investigated the spatial distribution, mass profiles, and benthic risk assessment of a wide range of methylsiloxanes (MSs), including 7 cyclic MSs (CMSs; D3-D9; the number refers to the number of SiO bonds), 13 linear MSs (LMSs; L3-L15), and 15 modified and other MSs (MMSs) in sediments from the Tokyo Bay catchment basin, Japan. We observed widespread distribution of MSs (ΣCMS, ΣLMS, and ΣMMS) in the sediment samples, with concentrations of 1.0-6180 ng/g dry weight (dw), 1.8-10,100 ng/g dw, and < 0.31-210 ng/g dw, respectively. Our study is the first to measure various MMSs modified with hydrogen, vinyl, or phenyl groups; however, only methyltris(trimethylsiloxy)silane and phenyltris(trimethylsiloxy)silane were detected with high occurrence frequency. Notably, no elevated concentrations of MSs were observed downstream of silicone manufacturers, whereas the sediment was characterized by a specific D4/D5 ratio. With the Si-based mass profiles in extractable organosilicon (EOSi), the measured CMSs, LMSs, and MMSs accounted for 5.4%, 7.8%, and 0.2%, respectively. Unidentified EOSi (unknown fraction) constituted a major proportion of the EOSi in the sediment, with a mean of 87%, suggesting that the organosilicon environmental emissions were more than the measured MSs. In risk assessment of the adverse effects of D4, D5, and D6 in sediment on benthic organisms, the respective distributions indicated no overlap between the 95th percentile field sediment concentration and the 5th percentile chronic sediment no-effect concentration in organic carbon-normalized concentration. Although the hazard quotient compared with the predicted no-effect concentration for D5 and D6 exceeded the threshold level (hazard quotient ≥1), the results of probabilistic risk assessment for the three CMSs were not high enough to indicate a threat to benthic organisms in the study area.
我们调查了日本东京湾流域沉积物中广泛存在的甲基硅氧烷（MSs）的空间分布、质量分布特征和底栖风险评估，包括 7 种环状 MSs（CMSs；D3-D9；数字表示 SiO 键的数量）、13 种线性 MSs（LMSs；L3-L15）和 15 种改性和其他 MSs（MMSs）。我们在沉积物样本中观察到 MSs（ΣCMS、ΣLMS 和 ΣMMS）的广泛分布，浓度分别为 1.0-6180ng/g 干重（dw）、1.8-10100ng/g dw 和 <0.31-210ng/g dw。我们的研究首次测量了各种用氢、乙烯基或苯基改性的 MMSs；然而，只有甲基三（三甲氧基硅基）硅烷和苯基三（三甲氧基硅基）硅烷被检测到具有高出现频率。值得注意的是，在有机硅制造商的下游没有观察到 MSs 的浓度升高，而沉积物的特征是特定的 D4/D5 比值。根据可提取有机硅（EOSi）中的 Si 质量分布，所测量的 CMSs、LMSs 和 MMSs 分别占 5.4%、7.8%和 0.2%。未识别的 EOSi（未知部分）构成了沉积物中 EOSi 的主要部分，平均占 87%，这表明有机硅环境排放物超过了所测量的 MSs。在评估 D4、D5 和 D6 在沉积物中对底栖生物的不利影响的风险时，各自的分布表明，95%分位数的现场沉积物浓度与有机碳归一化浓度的 5%慢性沉积物无效应浓度之间没有重叠。虽然 D5 和 D6 的危害商与预测无效应浓度相比超过了阈值水平（危害商≥1），但对这三种 CMSs 的概率风险评估结果还不足以表明研究区域底栖生物受到威胁。
