作者：Zheng, J., Chen, K., Wu, J. & Wu, J.

Microplastics (MPs) are emerging subsurface contaminants, yet their occurrence and transport potential in nearshore aquifers connected to large freshwater lakes remain poorly understood. This study characterized MPs in nearshore aquifers surrounding Taihu Lake using laser direct infrared (LDIR) spectroscopy and quantified their potential fluxes to the lake via lacustrine groundwater discharge (LGD) with a Rn-222-based model. MPs were detected in all ten shallow groundwater samples, with abundances ranging from 176 to 1526 particles/L (mean +/- SD: 576.9 +/- 404.6 particles/L). A total of 22 polymer types were identified, dominated by silicone, fluororubber, and chlorinated polyethylene, suggesting mixed domestic, industrial, and tourism-related sources. MPs were predominantly fine (< 50 mu m) fragments, a size-shape combination favoring transport through porous media. Under three size-dependent transport scenarios, first-order, dry-season baseline LGD-derived MP loads were estimated to range from 1339 +/- 966 to 3560 +/- 2738 trillion particles/yr by number and from 6.1 +/- 6.9 to 57.0 +/- 49.8 tons/yr by mass. For the 20-50 mu m fraction, the LGD-derived loads were of the same order of magnitude as the estimated annual riverine input. Although these estimates are subject to substantial uncertainty, these findings highlight the widespread presence of MPs in lakeshore shallow groundwater across a humid floodplain basin, and suggest that LGD could represent a previously underrecognized pathway for the transport of fine MPs to shallow lakes. This underscores the need to incorporate groundwater-surface water connectivity into future plastic pollution assessments.

微塑料（MPs）是一类新兴的地下污染物，然而其在与大型淡水湖泊相连的滨岸含水层中的赋存与迁移潜势仍知之甚少。研究利用激光直接红外光谱（LDIR）表征了太湖滨岸含水层中的微塑料，并基于镭-222（Rn-222）质量平衡模型，定量评估了其经湖泊地下水排泄（LGD）输入湖泊的潜在通量。10个浅层地下水样品中均检出微塑料，丰度介于176—1526粒/升之间（均值 ± 标准差：576.9 ± 404.6 粒/升）。共鉴定出22种聚合物类型，以有机硅、氟橡胶与氯化聚乙烯为主，提示存在生活、工业与旅游等混合来源。微塑料以细颗粒（< 50 μm）碎片为主，这一“粒径—形状”组合有利于其在多孔介质中的迁移。在三种基于粒径的迁移情景下，估算枯水期基流的LGD来源微塑料负荷（一阶估算）为：数量口径1339 ± 966 至 3560 ± 2738 万亿粒/年，质量口径6.1 ± 6.9 至 57.0 ± 49.8 吨/年。对于20—50 μm粒径组分，LGD来源负荷与估算的河流年入湖负荷处于同一数量级。尽管这些估算存在较大不确定性，本研究结果仍凸显了湿润洪泛平原流域湖滨浅层地下水中微塑料的普遍存在，并表明LGD可能是细粒径微塑料向浅水湖泊输运的一个此前未被充分认识的途径。这凸显了在未来塑料污染评估中纳入地下水—地表水连通性的必要性。

（来源：Water Research 2026  DOI: 10.1016/j.watres.2026.125821）