摘要

根据现场调查和模拟估算，河流被认为是微塑料到达海洋的重要途径。然而，只有少数研究直接评估了河流中微塑料的发生和归宿。在这项研究中，我们调查了长江中下游微塑性碎片的发生和命运，据估计，这是迄今为止最大的河流塑料碎片河源。长江中下游15个地点的微塑料丰度为1.95×105~9.00×105items / km2，平均为4.92×105items / km2。微塑料的丰度与中孔塑料的丰度正相关。大城市，大型河岸湖泊和海水侵蚀似乎是影响长江中微塑料分布的主要因素，而底栖和河岸沉积物的沉积可能导致部分河段的微塑料减少。这项研究的结果表明，在大型河流集水区产生的大量微塑料不会被运输到海洋，过去的微塑料通量模型估计可能包含偏差。到达海洋的微塑料流量应根据河流潮汐极限的长期监测来计算。更重要的是，保留在河流系统中的微塑料的命运和影响应该得到更多的关注。

Based on field investigations and modeling estimates, rivers are considered an important route taken by microplastics to reach the sea. However, only a few studies have directly assessed occurrence and fate of microplastics in rivers. In this study, we surveyed the occurrence and fate of microplastic debris in the middle and lower reaches of the Yangtze River, which was estimated to be the largest riverine source of plastic debris to the sea. The abundance of microplastics at 15 sites along the middle and lower reaches of the Yangtze River ranged from 1.95 × 105 to 9.00 × 105 items/km2 with an average of 4.92 × 105 items/km2. The abundance of microplastics was positively correlated with the abundance of mesoplastics. Megacities, large riparian lakes, and seawater encroachment appeared to be main factors affecting the distribution of microplastics in the Yangtze River, while the deposition to benthic and riparian sediments likely led to observed decreases in microplastics in some sections of the river. The results of this study indicate that a considerable amount of microplastics generated in large river catchments are not transported to the sea and past modeling estimates of microplastic flux may contain biases. The flux of microplastics reaching the sea should be calculated based on long-term monitoring at the tidal limit of rivers. More importantly, the fate and effects of microplastics retained in the river system should receive more attention.

https://www.ncbi.nlm.nih.gov/pubmed/30597469