School of Environment, Beijing Normal University, State Key Laboratory of Water Environment Simulation , Beijing 100875, China.
Environ Sci Technol. 2018 Jan 16;52(2):644-653. doi: 10.1021/acs.est.7b05520. Epub 2017 Dec 29.
Dissolved organic matter (DOM) is a key environmental factor for the bioavailability of hydrophobic organic compounds (HOCs) in natural waters. However, the bioavailability of DOM-associated HOCs is not clear. In this research, pyrene was selected as a model HOC, and its freely dissolved concentration (C) was maintained by passive dosing systems. The immobilization and pyrene content in the tissues excluding gut of Daphnia magna were examined to quantify the bioavailability of DOM-associated pyrene. The results indicated that DOM promoted the bioavailability of pyrene when the C of pyrene was kept constant, and the bioavailability of pyrene associated with DOM of various molecular weights was ordered as middle molecular weight (5 000-10 000 Da) DOM > lower molecular weight (<1 000, 1 000-3 000, and 3 000-5 000 Da) DOM > higher molecular weight (>10 000 Da) DOM. The influencing mechanisms of DOM molecular weight were related with the partition of pyrene between DOM and water, the uptake routes of DOM by D. magna, and the desorption or release of pyrene from DOM in the gut of D. magna. The findings obtained in this research suggest that the bioavailability of DOM-associated HOCs should be taken into account for the eco-environmental risk assessment of HOCs in water systems.
溶解有机质（DOM）是天然水中疏水性有机化合物（HOCs）生物可利用性的关键环境因素。然而，DOM 结合的 HOCs 的生物可利用性尚不清楚。在这项研究中，选择芘作为模型 HOC，并通过被动给药系统维持其自由溶解浓度（C）。测定了大型溞组织中除肠道外的芘的固定化和含量，以量化与 DOM 结合的芘的生物可利用性。结果表明，当芘的 C 保持恒定时，DOM 会促进芘的生物可利用性，并且与各种分子量的 DOM 结合的芘的生物可利用性顺序为中等分子量（5000-10000 Da）DOM > 低分子量（<1000、1000-3000 和 3000-5000 Da）DOM > 高分子量（>10000 Da）DOM。DOM 分子量的影响机制与芘在 DOM 和水中的分配、大型溞对 DOM 的摄取途径以及在大型溞肠道中从 DOM 中解吸或释放芘有关。本研究的结果表明，在水生系统中对 HOCs 进行生态环境风险评估时，应考虑 DOM 结合的 HOCs 的生物可利用性。
