Liu Fan, Lorenz Claudia, Zhao Guohan
Department of the Built Environment, Aalborg University, Thomas Manns Vej 23, 9200, Aalborg, Denmark.
Department of the Built Environment, Aalborg University, Thomas Manns Vej 23, 9200, Aalborg, Denmark; Department of Science and Environment, Roskilde University, Roskilde, 4000, Denmark.
Environ Res. 2025 Oct 15;283:122132. doi: 10.1016/j.envres.2025.122132. Epub 2025 Jun 10.
Land-based sources are the predominant contributors to marine microplastic pollution; however, identifying specific inland origins and their correspondence transport paths remain challenging at large-scale. In Denmark, terrestrial-marine connectivity is largely mediated by a complex network of streams, that further complicates hydrological connections between diverse inland discharges and the final coastal receptor. This study presents a GIS-based hydrological source tracking approach to identify the relevant inland discharges and further delineating their transportation paths for microplastics (≥10 μm) sampled from coastal sediments. After analyzed with Focal Plane Array-based Fourier Transform Infrared (FPA-μFTIR) imaging, samples from 13 Danish coastal monitoring stations were tested for souce tracking operations. The tracking tool first screened the stream network across Denmark to identify both point and non-point inland sources-stormwater runoff, wastewater effluent, and combined sewer overflow (CSO)-contributing microplastics to the selected coastal zones. Microplastics were detected at all stations, with variations in abundance, polymer composition, particle shape, and size. Significant positive correlations (p < 0.05) were observed between discharge volume and the composition of certain microplastics: wastewater effluent positively correlates with fiber and polyvinylchloride (PVC), while stormwater-associated discharges (including CSOs) correlated with polypropylene (PP). However, total microplastic concentration was not significantly linked to the discharges. Nevertheless, the GIS-based hydrological tool demonstrated an early-screening tool to identify inland source of marine microplastics. The results underscored the significant role of inland discharges in transporting distinct microplastics to coastal environment, offering valuable insights for authorities to further implement more targeted hydrodynamic modelling, source-specific mitigation strategies, as well as optimised station deployment strategies in future.
陆源是海洋微塑料污染的主要来源；然而，在大规模范围内确定具体的内陆源头及其相应的传输路径仍然具有挑战性。在丹麦，陆地与海洋的连通性很大程度上由复杂的溪流网络介导，这进一步使不同内陆排放与最终海岸受体之间的水文联系变得复杂。本研究提出了一种基于地理信息系统（GIS）的水文溯源方法，以识别相关的内陆排放，并进一步描绘从沿海沉积物中采集的微塑料（≥10微米）的运输路径。在用基于焦平面阵列的傅里叶变换红外（FPA-μFTIR）成像进行分析后，对来自丹麦13个沿海监测站的样本进行了溯源操作测试。该溯源工具首先筛选了丹麦的溪流网络，以识别向选定沿海区域输送微塑料的点源和非点源内陆源头——雨水径流、废水排放和合流污水溢流（CSO）。在所有站点都检测到了微塑料，其在丰度、聚合物组成、颗粒形状和大小方面存在差异。在排放量与某些微塑料的组成之间观察到显著的正相关（p<0.05）：废水排放与纤维和聚氯乙烯（PVC）呈正相关，而与雨水相关的排放（包括合流污水溢流）与聚丙烯（PP）相关。然而，微塑料的总浓度与排放量没有显著关联。尽管如此，基于GIS的水文工具证明是一种识别海洋微塑料内陆源头的早期筛选工具。结果强调了内陆排放在将不同微塑料输送到沿海环境中的重要作用，为当局未来进一步实施更有针对性的水动力模型、特定源头的缓解策略以及优化站点部署策略提供了有价值的见解。
