University of Victoria, Victoria, British Columbia, V8P 5C2, Canada,.
University of Victoria, Victoria, British Columbia, V8P 5C2, Canada,; Fisheries and Oceans Canada, Pacific Biological Station, Nanaimo, British Columbia V9T 6N7, Canada.
Sci Total Environ. 2019 Jun 1;667:124-132. doi: 10.1016/j.scitotenv.2019.02.346. Epub 2019 Feb 24.
Microplastic particles (MPs) are widely distributed in seawater. Fibrous MPs (microfibres) are often reported as the most commonly encountered shape of particle. To estimate MP concentrations in seawater, samples are often collected using towed nets (generally 300-350-μm mesh) and may underestimate the amount of microfibres present, which may pass through the mesh due to their narrow width. We compared the potential microplastic particle (PMP) concentration estimates provided by two different seawater sampling methods conducted at three commercial shellfish farms and three unfarmed sites in Baynes Sound, British Columbia, Canada. The methods were: 10-L bucket samples sieved through 63-μm mesh in situ and subsequently filtered through an 8-μm polycarbonate membrane; and 1-L bulk samples collected in jars and subsequently filtered to 8 μm. The jar samples yielded PMP concentrations averaging approximately 8.5 times higher than the bucket samples per L of water (at the site level), largely driven by differences in the number of microfibres. There was no significant difference in PNP concentration between shellfish farms and unfarmed sites. An analysis of MP concentrations and mesh sizes reported in the literature suggests that using a 300-350-μm mesh may underestimate total MP concentrations by one to four orders of magnitude compared with samples that are filtered through much smaller mesh sizes (e.g. <100 μm), despite the effect of sample volume. Particles <300 μm in diameter make up a large component of MPs commonly found in fish and invertebrates. As such, common sampling practices fail to adequately measure a biologically relevant class of MPs, thereby undermining the ability to quantify ecological risk. We suggest that seawater sampling methods be designed to filter to <10 μm (the approximate width of many microfibres), either using pressurized pumps for large-volume samples, or by using sufficient replication of small-volume discrete samples.
微塑料颗粒（MPs）广泛分布于海水中。纤维状 MPs（微纤维）通常被报道为最常见的颗粒形状。为了估算海水中的 MPs 浓度，通常使用拖网采集水样（通常网眼尺寸为 300-350-μm），这可能会低估微纤维的数量，因为微纤维的宽度较窄，可能会穿过网眼。我们比较了在加拿大不列颠哥伦比亚省贝奈斯湾的三个商业贝类养殖场和三个未养殖点使用两种不同的海水采样方法估算的潜在微塑料颗粒（PMP）浓度。这两种方法分别为：10-L 桶原位采集水样，用 63-μm 网筛过滤，然后用 8-μm 聚碳酸酯膜过滤；1-L 大体积水样用广口瓶采集，然后用 8-μm 滤膜过滤。每升水样中，广口瓶采集的水样的 PMP 浓度平均约为桶采集水样的 8.5 倍（在采样点水平上），主要是因为微纤维数量的差异。贝类养殖场和未养殖点的 PNP 浓度没有显著差异。对文献中报道的 MPs 浓度和网眼尺寸的分析表明，与使用更小网眼尺寸（如 <100 μm）过滤的水样相比，使用 300-350-μm 网眼采集的水样可能会将总 MPs 浓度低估一到四个数量级，尽管采样体积有影响。直径小于 300 μm 的颗粒构成了鱼类和无脊椎动物中常见 MPs 的主要成分。因此，常见的采样方法无法充分测量具有生物学相关性的一类 MPs，从而削弱了量化生态风险的能力。我们建议设计海水采样方法，使用加压泵采集大体积水样，或使用足够的小体积离散水样重复采集，将水样过滤至 <10 μm（许多微纤维的近似宽度）。
