College of Environment and Ecology, Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, Chongqing 400045, China.
College of Environment and Ecology, Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, Chongqing 400045, China.
J Hazard Mater. 2022 Jun 5;431:128522. doi: 10.1016/j.jhazmat.2022.128522. Epub 2022 Feb 21.
Riparian zone is a hub for microplastics (MPs), and MPs accumulation also changes the function of the riparian zone (e.g., carbon pool) to pose a great threat to river ecosystems. Although it is known that MPs can be aged for changing their characteristic after accumulating in riparian sediment, the effect of MP aging behavior on sediment dissolved organic matter (DOM) bioavailability and carbon emission has not been elucidated. In this study, effects of pristine and aged MPs on the DOM characteristics and components were investigated in sediment. The results showed that pristine MPs increased DOM humification and promoted the formation of larger molecular weight components, thereby reducing DOM bioavailability by approximately 1623% and inducing negative priming effect. However, inhibition of MPs on DOM bioavailability and the priming effect decreased with aging behavior. Mathematical models revealed that the fulvic acid-like substance of sediment DOM was the driven factor in the influence of sediment carbon stability. Further microbial analysis found that higher carbohydrate metabolism promoted DOM humification, thereby reducing CO emissions approximately by 1926% after MPs accumulation. Thus, this study provided an integrated picture to understand the risk of MPs accumulation in sediment for a long term on terrestrial and aquatic ecosystems.
河岸带是微塑料（MPs）的聚集地，MPs 的积累也改变了河岸带的功能（例如，碳库），对河流生态系统构成了巨大威胁。尽管已知 MPs 在河岸带沉积物中积累后会因老化而改变其特性，但 MPs 老化行为对沉积物溶解有机 matter（DOM）生物可利用性和碳排放的影响尚未阐明。在这项研究中，研究了原状 MPs 和老化 MPs 对沉积物中 DOM 特征和成分的影响。结果表明，原状 MPs 增加了 DOM 的腐殖化程度，并促进了更大分子量成分的形成，从而降低了 DOM 的生物可利用性约 16%23%，并诱导了负激发效应。然而，随着老化行为的发生， MPs 对 DOM 生物可利用性和激发效应的抑制作用降低。数学模型表明，沉积物 DOM 中的富里酸类物质是影响沉积物碳稳定性的驱动因素。进一步的微生物分析发现，较高的碳水化合物代谢促进了 DOM 的腐殖化，从而使 MPs 积累后 CO 排放减少约 19%26%。因此，本研究为理解 MPs 在陆地和水生生态系统中长期积累对沉积物的风险提供了一个综合的认识。
