Biological and Agricultural Engineering, North Carolina State University, Raleigh, NC, USA.
Biological and Agricultural Engineering, North Carolina State University, Raleigh, NC, USA; North Carolina Sea Grant, North Carolina State University, Raleigh, NC, USA.
Sci Total Environ. 2023 Jun 20;878:162940. doi: 10.1016/j.scitotenv.2023.162940. Epub 2023 Mar 20.
While microplastics (MP) have been found in aquatic ecosystems around the world, the understanding of drivers and controls of their occurrence and distribution have yet to be determined. In particular, their fate and transport in river catchments and networks are still poorly understood. We identified MP concentrations in water and streambed sediment at fifteen locations across the Neuse River Basin in North Carolina, USA. Water samples were collected with two different mesh sizes, a trawl net (>335 μm) and a 64 μm sieve used to filter bailing water samples. MPs >335 μm were found in all the water samples with concentrations ranging from 0.02 to 221 particles per m (p m) with a median of 0.44 p m. The highest concentrations were observed in urban streams and there was a significant correlation between streamflow and MP concentration in the most urbanized locations. Fourier Transform Infrared (FTIR) analysis indicated that for MPs >335 μm the three most common polymer types were polyethylene, polypropylene, and polystyrene. There were substantially more MP particles observed when samples were analyzed using a smaller mesh size (>64 μm), with concentrations ranging from 20 to 130 p m and the most common polymer type being polyethylene terephthalate as identified by Raman spectroscopy. The ratio of MP concentrations (64 μm to 335 μm) ranged from 35 to 375, indicating the 335 μm mesh substantially underestimates MPs relative to the 64 μm mesh. MPs were detected in 14/15 sediment samples. Sediment and water column concentrations were not correlated. We estimate MP (>64 μm) loading from the Neuse River watershed to be 230 billion particles per year. The findings of this study help to better understand how MPs are spatially distributed and transported through a river basin and how MP concentrations are impacted by land cover, hydrology, and sampling method.
虽然微塑料（MP）已在世界各地的水生生态系统中被发现，但对其发生和分布的驱动因素和控制因素的了解仍有待确定。特别是，它们在河流流域和网络中的命运和迁移仍知之甚少。我们在美国北卡罗来纳州的 Neuse 河流域的 15 个地点确定了水中和河床沉积物中的 MP 浓度。水样使用两种不同的网目尺寸采集，一种是拖网（>335 μm），另一种是用于过滤汲水水样的 64 μm 筛子。所有水样中均发现>335 μm 的 MPs，浓度范围为 0.02 至 221 个颗粒/米（p m），中位数为 0.44 p m。在城市溪流中观察到的浓度最高，并且在最城市化的地点，溪流流量与 MP 浓度之间存在显著相关性。傅里叶变换红外（FTIR）分析表明，对于>335 μm 的 MPs，三种最常见的聚合物类型是聚乙烯、聚丙烯和聚苯乙烯。当使用较小的网目尺寸（>64 μm）分析样品时，观察到的 MP 颗粒数量要多得多，浓度范围为 20 至 130 p m，最常见的聚合物类型是通过拉曼光谱鉴定的聚对苯二甲酸乙二醇酯。MP 浓度（64 μm 至 335 μm）的比值范围为 35 至 375，表明 335 μm 的网目相对于 64 μm 的网目大大低估了 MPs。在 14/15 的沉积物样本中检测到 MPs。沉积物和水柱浓度之间没有相关性。我们估计 Neuse 河流域的 MP（>64 μm）负荷为每年 2300 亿个颗粒。本研究的结果有助于更好地了解 MPs 如何在流域内空间分布和迁移，以及土地覆盖、水文学和采样方法如何影响 MP 浓度。
