Microplastics in a Stormwater Pond

Large amounts of microplastics (MPs) enter our environment through runoff from urban areas. This study presents results for MPs in stormwater from a wet retention pond in terms of its water, sediments, and vertebrate fauna. The analysis was done for the size range 10–500 μm, applying a focal-plane array-based µFourier transform infrared (FPA-µFTIR) imaging technique with automated data analysis. Sample preparation protocols were optimized towards this analytical method. The study revealed 270 item L−1 in the pond water, corresponding to 4.2 µg L−1. The MPs in the pond were highly concentrated in its sediments, reaching 0.4 g kg−1, corresponding to nearly 106 item kg−1. MPs also accumulated in vertebrates from the pond—three-spined sticklebacks and young newts. In terms of particle numbers, this accumulation reached levels nearly as high as in the sediments. The size of the MPs in the pond water and its fauna was quite similar and significantly smaller than the MPs in the sediments. A rough estimate on MPs retention in the pond indicated that MPs were retained at efficiencies similar to that of other particulate materials occurring in the stormwater runoff.