National Observation and Research Station of Coastal Ecological Environments in Macao, Macao Environmental Research Institute, Macau University of Science and Technology, Macao SAR, China; State Key Laboratory of Marine Pollution and Department of Chemistry, City University of Hong Kong, Hong Kong SAR, China; Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai, China; Center for Ocean Research in Hong Kong and Macau (CORE), The Hong Kong University of Science and Technology, Hong Kong SAR, China.
State Key Laboratory of Marine Pollution and Department of Chemistry, City University of Hong Kong, Hong Kong SAR, China.
Water Res. 2022 Sep 1;223:118992. doi: 10.1016/j.watres.2022.118992. Epub 2022 Aug 17.
The release of microplastics from sewage treatment works (STWs) into the oceans around coastal cities is well documented. However, there are fewer studies on the microplastic abundance in stormwater drains and their emissions into the coastal marine environment via sewage and stormwater drainage networks. Here, we comprehensively investigated microplastic abundance in 66 sewage and 18 sludge samples collected from different process stages at three typical STWs and 36 water samples taken from six major stormwater drains during the dry and wet seasons in Hong Kong, which is a metropolitan city in south China. The results showed that microplastics were detected in all the sewage and stormwater samples, with the abundance ranging from 0.07 to 91.9 and from 0.4 to 36.48 particles/L, respectively, and in all the sludge samples with the abundance ranging from 167 to 936 particles/g (d. w.). There were no significant seasonal variations in the microplastic abundance across all samples of sewage, sludge, and stormwater. For both waterborne sample types, a smaller size (0.02-0.3 mm) and fiber shape were the dominant characteristics of the microplastics. Polyethylene terephthalate (PET) and polypropylene (PP) were the most abundant polymer types in the sewage samples, while polyethylene (PE), PET, PP, and PE-PP copolymer were the most abundant polymer types in the stormwater samples. The estimated range of total daily microplastic loads in the effluent from STWs in Hong Kong is estimated to be 4.48 × 10 - 2.68 × 10 particles/day, demonstrating that STWs are major pathways of microplastics in coastal environments despite the high removal percentage of microplastics in sewage treatment processes examined. This is the first comprehensive study on microplastics in the urban waters of a coastal metropolis. However, further studies on other coastal cities will enable an accurate estimation of the microplastic contribution of stormwater drains to the world's oceans.
污水处理厂（STWs）将微塑料释放到沿海城市周围的海洋中已经有充分的记录。然而，关于暴雨排水道中微塑料的丰度及其通过污水和雨水排水网络排放到沿海海洋环境中的研究较少。在这里，我们全面调查了来自中国南部大都市香港的三个典型 STW 的不同处理阶段的 66 个污水和 18 个污泥样本以及 6 个主要雨水排水道的 36 个水样中的微塑料丰度，这些样本是在旱季和雨季采集的。结果表明，所有污水和雨水样本中都检测到了微塑料，丰度范围分别为 0.07 至 91.9 和 0.4 至 36.48 个/升，所有污泥样本中丰度范围为 167 至 936 个/克（干重）。所有污水、污泥和雨水样本的微塑料丰度均无明显季节性变化。对于这两种水样类型，较小的尺寸（0.02-0.3 毫米）和纤维形状是微塑料的主要特征。聚对苯二甲酸乙二醇酯（PET）和聚丙烯（PP）是污水样本中最丰富的聚合物类型，而聚乙烯（PE）、PET、PP 和 PE-PP 共聚物是雨水样本中最丰富的聚合物类型。香港 STW 出水中总日微塑料负荷的估计范围估计为 4.48×10 - 2.68×10 个/天，这表明尽管污水处理过程中微塑料的去除率很高，但 STW 仍然是沿海环境中微塑料的主要途径。这是对沿海大都市城市水域中微塑料的首次全面研究。然而，对其他沿海城市的进一步研究将能够准确估计雨水排水道对世界海洋中微塑料的贡献。
