EVALUATION OF WATER SAMPLING TECHNIQUES USED FOR DETERMINATION OF MICROPLASTIC ABUNDANCE

Microplastic particles (≤ 5mm in size) are an environmental and public health concern. Water testing is necessary to monitor the quantity and movement of MPs through natural systems. Although there are commonly used water sampling techniques and microplastic separation techniques, there are no standard methods for collecting and quantifying microplastics in streams. The work presented here investigates techniques used to collect water samples for the quantification of microplastics. Samples for this study were collected from first- to fourth-order streams in the Nickajack Reservoir watershed, southeastern Tennessee and northwestern Georgia using two common water sampling techniques. One surface-water sample was collected using a grab sample from the thalweg of the stream from 19 streams. The second sample collection method involved collecting a grab sample from the surface of the stream and just above the sediment layer along the left bank of the stream and in the center of the stream. This created a partial cross-section of the stream and provided 4 grab samples for 6 of the 19 streams. Using best-practice techniques determined by a previous study (White et al., 2024), microplastics were separated from the collected water samples and quantified. The concentrations of microplastics from the single grab samples of surface water will be compared to those in the grab samples collected along a partial cross-section of the streams to identify the variation in microplastic quantities observed between the two sampling methods. The results will provide insight into where, and how many, samples should be taken in a stream to ensure a representative value for quantifying microplastic particles in streams.