Microplastics (MPs) are one of the major ecological concerns of the last years and despite the increasing interest and the rise of many studies regarding freshwater habitats, many aspects about distribution patterns, transport pathways and impacts of MPs in those systems need to be investigated. The present study characterizes the temporal trends of MP concentrations in waters of a riverine stretch of the northeastern Italy, subject to flow rate variations and investigates the MP accumulations patterns in the leaf litter, simulated in situ via leaf bag technique. MP concentrations in the water were significantly and negatively correlated to the flow rate regimes, with higher concentrations observed during low discharge periods. MPs accumulation in leaf bags agreed with trends observed in the water and the presence of wastewater discharge points positively affects the levels of MP contaminations within the leaf bags. These findings seem to suggest that the maintenance of a hydrological regime at relatively high levels in the investigated system could allow to maintain the self-purifying riverine processes and the disposal of microplastics like any other polluting substance. The use of leaf bag technique for the purpose to investigate MP accumulation trends on field provided useful information, is easy to modulate in terms of time periods and allow to record the evolution of the MP patterns also in relation to high flow rate episodes. Our results suggest that the method can be employed in new a perspective, to improve the knowledge about one of the major threats of the Anthropocene.

微塑料 (MP) 是近年来主要的生态问题之一，尽管人们对淡水栖息地的兴趣日益浓厚，许多研究也在兴起，但有关微塑料在这些系统中的分布模式、运输途径和影响的许多方面仍需要进行调查。本研究描述了意大利东北部河段水域中 MP 浓度随流速变化的时间趋势，并通过叶袋技术现场模拟，研究了落叶层中 MP 的积累模式。水中的 MP 浓度与流量状态呈显着负相关，在低流量期间观察到较高的浓度。叶袋中 MP 的积累与水中观察到的趋势一致，废水排放点的存在对叶袋内 MP 污染水平产生积极影响。这些发现似乎表明，在所研究的系统中将水文状况维持在相对较高的水平，可以维持河流的自净化过程，并像任何其他污染物质一样处理微塑料。使用叶袋技术来调查现场 MP 积累趋势提供了有用的信息，易于在时间段上进行调节，并且允许记录与高流速事件相关的 MP 模式的演变。我们的结果表明，可以从新的角度采用该方法，以提高对人类世主要威胁之一的认识。