Document Type
Dissertation
Date of Award
5-31-2024
Degree Name
Doctor of Philosophy in Environmental Engineering - (Ph.D.)
Department
Civil and Environmental Engineering
First Advisor
Michel Boufadel
Second Advisor
Ashish D. Borgaonkar
Third Advisor
Taha F. Marhaba
Fourth Advisor
Matthew J. Bandelt
Fifth Advisor
William Pennock
Sixth Advisor
Dibyendu Sarkar
Abstract
Microplastics (MPs) are increasingly recognized as a pervasive environmental contaminant, conveying other contaminants, accumulating in aquatic organisms, and posing ecological risks. The existing research has primarily focused on MPs in wastewater treatment plant effluents in surface waters. However, the role of stormwater systems in MP transport has been less explored. Given the rise in MPs from urban sources, stormwater runoff from urban areas may serve as a critical conduit for transporting land-based MPs into aquatic environments. Green infrastructures (GIs) have been recognized for mitigating flooding and improving water quality from minor storms by trapping stormwater pollutants. Yet, the capability of these systems to retain MPs from stormwater, especially in size <μm, remains inadequately understood. This study quantified and characterized MPs in urban runoff and GIs located in Newark, NJ. The spatial and temporal variation of MPs in GIs were also quantified. MP measurements were conducted using Fourier transform infrared spectrometer, Raman microscope, and Nile red staining techniques to quantify a wide range of MP sizes (1 μm 5 mm).
The MP concentrations in stormwater runoff varied with the land uses, with the highest concentration of 168.7± 37.1 pL-1 (particle) in highway, followed by 67.7± 11.3 pL-1 in commercial, and 23 ± 10.3 pL-1 in residential areas. The study identified specific polymers prevalent in different settings, notably polymethylmethacrylate and ethylene - vinyl acetate on highways and various other polymers like cellophane and polystyrene in commercial areas. MPs smaller than 125 μm constituted 49% of the total numbers.
In GIs, the overall mean concentration varied between sampling sites from 470 pkg-1 to 1000 pkg-1, with polypropylene as the dominant polymer, followed by nylon and polyethylene. With the GIs, larger MPs (250 μm-5 mm) were effectively retained within the top 5 cm. Small-sized MPs (1-250 μm) were prevalent at deeper depths (10 cm), and no MPs were found below 15 cm, suggesting a limited risk of groundwater pollution. In the horizontal direction of MP distribution, the highest MP concentration was observed near the stormwater inlet. During the three sampling periods, an increase in concentration was observed at all sites, indicating that MP accumulation in rain gardens is increasing over time.
The research has an engineering education component that accelerates the transfer of knowledge of MP research into the classroom and community. The study integrated the MP research into traditional engineering courses through enhancements to the syllabi with the aid of three case studies and community outreach. Virtual Reality (VR) was used to develop training videos for students and communities.
Overall, the study found a high concentration of MPs in urban systems and provided a framework for quantifying them, which will help communities to pursue informed interventions to reduce MPs in water bodies. The study provided guidelines for monitoring and maintaining GIs and promoting sustainable and resilient urban environments. Finally, the study demonstrated viable strategies to bridge the gap between cutting-edge research and students and the community at large.
Recommended Citation
Parameswarappa Jayalakshmamma, Meghana, "Microplastic abundance and removal in stormwater using green infrastructure" (2024). Dissertations. 1822.
https://digitalcommons.njit.edu/dissertations/1822
