Microplastic Occurrence and Polymer Confirmation in Five Houston Urban Waterways

Polymer-confirmed freshwater microplastic data remain limited for Houston urban waterways. We screened five waterways during one winter baseflow period using inverted microscopy with Raman and ATR-FTIR confirmation of particles from 75 μm to 2 mm. Visually identified suspected plastic particles were observed in samples from all five waterways, with concentrations ranging from 8.7 to 9.2 particles L⁻¹. Fragments dominated most samples, while Buffalo Bayou and Vince Bayou showed higher fiber contributions. Spectroscopic analysis screened for a broad range of synthetic polymers and confirmed the occurrence of polyethylene terephthalate (PET), polyethylene (PE), and polypropylene (PP) among the analyzed particles. Because each waterway was represented by one composite sample and limited blank controls, the results should be interpreted as an initial descriptive screening dataset rather than as statistically generalizable site comparisons or quantitative polymer-abundance measurements.