DO WIND AND RAINFALL AFFECT
SURFACE MICROPLASTIC CONCENTRATIONS IN TAMPA BAY?
Rose Queally1, Adam Wiatrowski1, John Hilliard1, Abigail Hunt1,
Shannon Gowans1,2, Amy NS Siuda1
Eckerd College, St. Petersburg, FL
1Marine Science Discipline, 2Biology Discipline
Conclusions and Future Directions
- Microplastics (<5mm) negatively affect the ecosystem and the environment
- Tampa Bay is an estuarine environment that holds habitats and nurseries for several species
- As an urban watershed, Tampa Bay exhibits higher levels of runoff
- Microplastics can enter Tampa Bay through rivers, storm drains, runoff and directly through littering
- This study monitors microplastic concentrations in Tampa Bay surface waters and investigates correlations with rainfall and wind speed
Funding from EC Natural Sciences Summer Research Program, Hillsborough EPC and Tampa Bay Environmental Restoration Fund.
- Surface water samples were collected from 7 stations throughout Tampa Bay in 20L buckets (saltwater flow marked in blue, rivers in green, and major runoff sources in red)
- Plastics collected through sequential 20 and 212µm stainless steel sieves
- Stained with Nile Red and filtered onto 5µm black filters
- Plastics photographed via fluorescence microscopy under cyan light
- Particles quantified with ImageJ
- Wind speed and rainfall data obtained from the Tampa Bay Water Atlas
- Rainfall analysis excluded days lacking previous day rainfall
- Weak negative correlation (R= 0.25) between microplastic concentration and prior-day rainfall
- Correlation influenced by the small number of samples collected after heavy rains
- Weak positive correlation (R= 0.04) between microplastic concentration and same-day winds
- Field logistics prevented sampling in high winds, so a limited range of wind speeds were sampled
- No clear spatial distribution
- While large macroplastics require relatively heavy rainfall to be washed into Tampa Bay, microplastics can be carried by light rainfall
- Statistically insignificant correlations found between both rainfall levels and wind speed
- Limited sampling at high rainfall obfuscated trends, suggesting low rainfall is more effective at transporting microplastics. Additional sampling across a wider range of rainfall levels will elucidate potential correlations
- Other studies show positive correlations between wind speeds and microplastic concentrations (Bullard 2021, Rezaei 2019). Sampling was unable to be conducted above wind speeds of 15 knots. Further research could focus on sampling during higher wind speeds to research possible correlations
- Further research is needed to draw conclusions about the specific impacts of individual wind and rainfall events
Bullard JE, Ockelford A, O'Brien P, McKenna Neuman C. 2021. Preferential transport of microplastics by wind. Atmos Environ. 245:118038.
Rezaei M, Riksen MJPM, Sirjani E, Sameni A, Geissen V. 2019. Wind erosion as a driver for transport of light density microplastics. Sci Total Environ. 669:273-281.