Nutile Samuel A, Harwood Amanda D, Sinche Federico L, Huff Hartz Kara E, Landrum Peter F, Lydy Michael J
Center for Fisheries, Aquaculture and Aquatic Sciences and Department of Zoology, Southern Illinois University, Carbondale, IL 62901, USA.
Biology and Environmental Studies, Alma College, Alma, MI 48801, USA.
Chemosphere. 2017 Mar;171:308-317. doi: 10.1016/j.chemosphere.2016.12.045. Epub 2016 Dec 13.
Use of Tenax extractable concentrations to estimate biological exposure to hydrophobic organic contaminants is well documented, yet method variation exists between studies, specifically in the ratio of Tenax mass to organic carbon mass in the sediment (Tenax:OC ratio) being extracted. The effects of this variation on exposure estimates are not well understood. As Tenax is theoretically in direct competition with organic carbon for freely dissolved chemical in sediment interstitial water, varying the Tenax:OC ratio could impact single-point Tenax extraction (SPTE) exposure estimates. Therefore, the effects of varying Tenax:OC ratios on SPTE pyrethroid concentrations from field-contaminated and laboratory-spiked sediments were compared to bioaccumulation by Lumbriculus variegatus. The Tenax:OC ratio had minimal effect on SPTE pyrethroid concentrations. The SPTE pyrethroid concentrations obtained using the highest and lowest Tenax:OC ratios ranged from 0.85- to 3.91-fold different, which is unlikely to contribute substantial error to bioaccessibility estimates. Comparisons to Tenax exposure endpoints from previous research reveal the variation in these endpoints is likely due to toxicokinetic and toxicodynamic differences; processes common to exposure estimates provided by any chemical extraction technique. As the pyrethroid concentrations in the experimental sediments caused toxicity to L. variegatus, thus affecting bioaccumulation, the SPTE concentrations overestimated bioaccumulation. However, SPTE concentrations strongly correlated with growth inhibition regardless of the Tenax:OC ratio, providing accurate estimates of the correct exposure endpoint. Tenax masses of 0.500-0.800 g should provide sufficient Tenax to achieve Tenax:OC ratios of at least 5:1, which will provide accurate exposure estimates while retaining the ease of conducting SPTEs.
使用Tenax可提取浓度来估计对疏水性有机污染物的生物暴露已有充分记录，但不同研究之间存在方法差异，特别是在被提取沉积物中Tenax质量与有机碳质量的比例（Tenax:OC比例）方面。这种差异对暴露估计的影响尚未得到充分理解。由于理论上Tenax与有机碳在沉积物间隙水中对自由溶解的化学物质存在直接竞争，改变Tenax:OC比例可能会影响单点Tenax萃取（SPTE）暴露估计。因此，将不同Tenax:OC比例对来自现场污染和实验室加标沉积物的SPTE拟除虫菊酯浓度的影响与颤蚓的生物累积情况进行了比较。Tenax:OC比例对SPTE拟除虫菊酯浓度的影响最小。使用最高和最低Tenax:OC比例获得的SPTE拟除虫菊酯浓度相差0.85至3.91倍，这不太可能对生物可及性估计造成重大误差。与先前研究中的Tenax暴露终点进行比较表明，这些终点的差异可能是由于毒代动力学和毒效动力学差异所致；这些过程是任何化学萃取技术提供的暴露估计所共有的。由于实验沉积物中的拟除虫菊酯浓度对颤蚓产生了毒性，从而影响了生物累积，因此SPTE浓度高估了生物累积。然而，无论Tenax:OC比例如何，SPTE浓度与生长抑制都具有很强的相关性，能够准确估计正确的暴露终点。0.500 - 0.800 g的Tenax质量应能提供足够的Tenax以实现至少5:1的Tenax:OC比例。这将在保持进行SPTE操作简便性的同时提供准确的暴露估计。
