Goldilocks and the three surface water sampling methods

, Markley Laura, Driscoll Charles, Costello Staniec Andria, Huth Ellenora.

While one method's sampling volume is too low, others present challenges with contamination and sample processing. Which is just right? Sampling microplastics in fresh surface waters can be difficult given the variable accessibility and quality of bodies of water. Choosing the right sampling method is integral to collecting accurate data, while also keeping costs and potential challenges to a minimum. We employed three distinct surface water sampling methods on freshwater lakes and streams in central New York: trawling with a 300 micron microplastic sampling net, bulk sampling with 1L mason jars, and bucket-to-bucket sampling through variable sieve sizes. This study reflects on the applicability of these three sampling methods and potential variations between them based on our ongoing work and those reported by other studies. While bulk sampling was the easiest method, it also obtained the least quantifiable microplastics using visual ID. By contrast, trawling was more time-intensive, contamination prone, and presented the most challenges for organics processing because of the high inputs of leafy debris. However, trawling sampled the highest volume and had the most visually identifiable microplastics. Depending on sample location, bucket-to-bucket sampling had characteristics of both bulk and trawl sampling but was the most flexible as far as cost and accessibility. This work further reflects on the context in which each method is useful and how processing and counting methodology could impact sampling method decision making.

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