UMR 5623 IMRCP (Laboratoire des Interactions Moléculaires et Réactivité Chimique et Photochimique), CNRS, Université Toulouse III Paul Sabatier, 118 route de Narbonne, 31062 Toulouse, France; UMR 5174 EDB (Laboratoire Évolution and Diversité Biologique), CNRS, Université Toulouse III Paul Sabatier, 118 route de Narbonne, 31062 Toulouse, France.
UMR 5623 IMRCP (Laboratoire des Interactions Moléculaires et Réactivité Chimique et Photochimique), CNRS, Université Toulouse III Paul Sabatier, 118 route de Narbonne, 31062 Toulouse, France; UMR 5174 EDB (Laboratoire Évolution and Diversité Biologique), CNRS, Université Toulouse III Paul Sabatier, 118 route de Narbonne, 31062 Toulouse, France.
Sci Total Environ. 2021 May 15;769:144479. doi: 10.1016/j.scitotenv.2020.144479. Epub 2021 Jan 4.
Microplastic (MP) pollution represents a novel environmental pressure acting on freshwater ecosystems. Improving our understanding of the dynamics of MP pollution in freshwater ecosystems is therefore a prerequisite for managing and limiting this pollution. In this study, we quantified the spatial and temporal variability of MP (size range 700 μm - 5 mm) pollution in surface water in 14 sites located across the Garonne river catchment (Southwestern France, 6 in the main river and 8 tributaries). MP concentration averaged 0.15 particles.m (± 0.46 SD) and strongly varied both in space and in time. We found that the spatial variation in MP concentration was driven by urbanization and that the temporal variation in MP concentration and MP size was driven by hydrological conditions, with higher concentrations and smaller particles sizes in warm seasons with low discharge. Polyethylene (44.5%), polystyrene (30.1%) and polypropylene (18.2%) were the main polymers and their proportion did not vary significantly across sampled sites. Particle color was associated with polymer type, with a high proportion of white particles in polystyrene. We also found a significant and negative relationship between MP size and the distance to the source in sites located in the main stream. MP pollution across watershed, from headwater tributaries to lowland rivers, is dynamic, and further studies are needed to improve the resolution of our knowledge of spatial and temporal patterns of MP pollution in freshwater ecosystems.
微塑料（MP）污染是作用于淡水生态系统的一种新型环境压力。因此，了解淡水生态系统中 MP 污染的动态变化是管理和限制这种污染的前提。在这项研究中，我们量化了法国西南部加龙河流域 14 个地点地表水（大小范围为 700 μm-5 mm）中 MP 污染的时空变化。MP 浓度平均为 0.15 个颗粒/米（±0.46 标准差），在空间和时间上均有强烈变化。我们发现，MP 浓度的空间变化受城市化驱动，而 MP 浓度和粒径的时间变化受水文条件驱动，在低流量的温暖季节，浓度较高，粒径较小。聚乙烯（44.5%）、聚苯乙烯（30.1%）和聚丙烯（18.2%）是主要的聚合物，其比例在采样点之间没有显著差异。颗粒颜色与聚合物类型有关，聚苯乙烯中白色颗粒的比例较高。我们还发现，位于干流的地点中，MP 粒径与距源的距离之间存在显著的负相关关系。从上游支流到低地河流，整个流域的 MP 污染是动态的，需要进一步研究来提高我们对淡水生态系统中 MP 污染时空模式的认识。
