Moses Sonya R, Löder Martin G J, Herrmann Frank, Laforsch Christian
Department of Animal Ecology I and BayCEER, University of Bayreuth, Universitätsstr. 30, 95440 Bayreuth, Germany.
Institute of Bio- and Geosciences (IBG), Institute 3: Agrosphere, Forschungszentrum Jülich GmbH (FZJ), 52425 Jülich, Germany.
Sci Total Environ. 2023 Dec 1;902:166463. doi: 10.1016/j.scitotenv.2023.166463. Epub 2023 Aug 21.
Rivers play a major role in the distribution of microplastics (MPs) in the environment, however, research on temporal variations in these highly dynamic systems is still in its infancy. To date, most studies dealing with the seasonality of MP contamination in rivers focus on bi-yearly analysis, while temporal fluctuations over the course of the year are rarely studied. To shed more light on seasonal variability of MP abundance and potential driving factors, we have thus sampled the water surface of one location in the Weser River in Germany monthly over one entire year. In our study, we targeted MP in the size range 10-5000 μm, using two different state-of-the-art sampling methods (manta net for large MP (l-MP; 500-5000 μm) and a filtration system for small MP (s-MP; 10-500 μm)) and analysis techniques (ATR-FTIR and FPA-μFTIR) for chemical identification. Our findings show a strong size-dependent positive correlation of the MP concentration with discharge rates (specifically direct runoff) and suspended particulate matter (SPM) for s-MPs, specifically in the size range 10-149 μm. L-MPs, however, show a different environmental behaviour and do not follow these patterns. With our study, we were able to deliver a much higher temporal resolution, covering a broader size range of MPs compared to most studies. Our findings point towards an interplay of two possible mechanisms: a) the riverbeds play an important role in large-scale MP and SPM release via resuspension during high discharge events, and b) precipitation-driven soil erosion and runoff from urban surfaces (e.g. rain sewers) introduce MP and SPM. Hence, our study serves as a basis for more detailed investigations of MP transport in and between ecosystems.
河流在微塑料（MPs）于环境中的分布方面起着主要作用，然而，对这些高度动态系统中的时间变化的研究仍处于起步阶段。迄今为止，大多数关于河流中MP污染季节性的研究都集中在两年一次的分析上，而一年中各时段的时间波动则很少被研究。为了更深入了解MP丰度的季节变化及其潜在驱动因素，我们在一整年的时间里每月对德国威悉河一个地点的水面进行采样。在我们的研究中，我们针对尺寸范围为10 - 5000微米的MP，使用了两种不同的先进采样方法（用于大尺寸MP（l - MP；500 - 5000微米）的蝠鲼网和用于小尺寸MP（s - MP；10 - 500微米）的过滤系统）以及用于化学鉴定的分析技术（衰减全反射傅里叶变换红外光谱法（ATR - FTIR）和焦平面阵列显微傅里叶变换红外光谱法（FPA - μFTIR））。我们的研究结果表明，对于s - MPs，尤其是尺寸范围在10 - 149微米的MP，其浓度与排放率（特别是直接径流）和悬浮颗粒物（SPM）之间存在强烈的尺寸依赖性正相关。然而，l - MPs表现出不同的环境行为，并不遵循这些模式。通过我们的研究，与大多数研究相比，我们能够提供更高的时间分辨率，涵盖更广泛的MP尺寸范围。我们的研究结果指向两种可能机制的相互作用：a）河床在高流量事件期间通过再悬浮在大规模MP和SPM释放中起重要作用，b）降水驱动的土壤侵蚀和城市地表（如下水道）的径流引入了MP和SPM。因此，我们的研究为更详细地研究MP在生态系统内部和之间的传输提供了基础。
