Center for Global Health, School of Public Health, Nanjing Medical University, Nanjing 211166, China; State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 10012, China.
College of Life Science, Yantai University, Yantai 264005, China.
Sci Total Environ. 2020 Aug 10;729:139025. doi: 10.1016/j.scitotenv.2020.139025. Epub 2020 Apr 27.
Microplastics are an emerging pollutant of international concern due to its wide distribution through various pathways. Estuary is an important pathway for land microplastics to enter into the oceans by rivers. In this study, we hypothesized that microplastics would sink into estuary sediment during diffusion and transmission from river before entering into the sea, which results in higher accumulation of microplastics in proximity to river-estuary than in the oceans. In order to demonstrate this hypothesis, sediment samples were collected from an estuary and its two main inputting rivers and the microplastics in these samples were analyzed. In the collected sediment samples, 19 types of polymers, including the three most common polymers (polyethylene, polyethylene terephthalate, and poly(propylene:ethylene)), were identified and confirmed by FT-IR. Eight types of polymers were consistently detected in all samples, while 11 types of polymers were occasionally found in some samples. These microplastics exhibited four shapes and their percentages followed the high-to-low order of film, fragment, fiber and pellet. A relatively lower abundance of microplastics was found in river sediments from Shuangtaizi River with an average of 170 ± 96 particles/kg d.w., compared to that from Daliao River with an average of 237 ± 129 particles/kg d.w., but it was higher than that from Liaohe Estuary with an average of 120 ± 46 particles/kg d.w. Furthermore, the highest concentration of microplastics was found at the mouth of rivers, showing high accumulation where the freshwater and saltwater meet. Results from this study, including the abundance, characteristics and spatial distribution of microplastic pollution in sediments from an interconnected river-estuary system, revealed the fate and distribution of microplastics in the river and estuary environment.
微塑料是一种新兴的污染物，由于其通过各种途径广泛分布，引起了国际关注。河口是陆地微塑料通过河流进入海洋的重要途径。在本研究中，我们假设在微塑料从河流扩散和传输到海洋之前，微塑料会在河口沉积物中下沉，从而导致靠近河流-河口的微塑料积累高于海洋。为了验证这一假设，我们从一个河口及其两个主要输入河流采集了沉积物样本，并对这些样本中的微塑料进行了分析。在采集的沉积物样本中，共鉴定并通过傅里叶变换红外光谱（FT-IR）确认了 19 种聚合物，包括三种最常见的聚合物（聚乙烯、聚对苯二甲酸乙二醇酯和聚（丙烯：乙烯））。所有样本中均一致检测到 8 种聚合物，而 11 种聚合物则偶尔出现在某些样本中。这些微塑料呈现出四种形状，其百分比依次为薄膜、碎片、纤维和颗粒。双台子河沉积物中的微塑料丰度相对较低，平均为 170±96 个/千克干重，而大辽河沉积物中的微塑料丰度平均为 237±129 个/千克干重，但高于辽河河口沉积物中的微塑料丰度，平均为 120±46 个/千克干重。此外，微塑料浓度最高的地方在河流入海口，在淡水和盐水相遇的地方有很高的积累。本研究结果包括连通的河流-河口系统沉积物中微塑料污染的丰度、特征和空间分布，揭示了微塑料在河流和河口环境中的命运和分布。
