We can't find the internet
Attempting to reconnect
Something went wrong!
Hang in there while we get back on track
Microplastics in urban wastewater and estuarine water: Importance of street runoff
Summary
Microplastics ranging from 10 micrometers to 5 mm were measured in untreated sewage, treated sewage, highway runoff, and estuarine water in Tokyo during dry and wet weather. Particles smaller than 200 micrometers made up more than 60% of total microplastic counts across all sample types, with highway runoff identified as a significant contributor.
We measured microplastics [(MPs): 10 μm–5 mm] in untreated and secondary-treated sewage, highway runoff, and estuarine water in Tokyo, Japan, during both dry and wet weather. MPs smaller than 200 μm were predominant, making up>60% of the total number, in all our water samples. The abundance of the MPs was 420 pieces/L in the influent and 8.7 pieces/L in the secondary effluent, indicating a removal efficiency of 98% during primary+secondary treatment. Of the measured polymers—polyethylene (PE), polypropylene, polystyrene, polyethyleneterephthalate (PET), polyethylene polypropylene copolymer, polyethylene polypropylene diene (PEPD), polyethylene vinyl acetate, and acrylonitrile styrene, PET was predominant in the sewage influent (88%) and effluent (49%) and its form was mostly fibrous, indicating contribution from laundry effluents. Highway runoff water samples contained high concentrations of MP (81–292 pieces/L). The highway runoff contained more PE (25%–49%) and PEPD (13%–30%) than PET (3%–12%) indicating contribution from debris from automobile tire wear and plastics weathered on the ground. MP concentrations in estuarine water samples were lower (1.4–2.3 pieces/L in dry weather), and PET was predominant, at 52%–77%, indicating a dominant contribution from sewage effluent. Following rainfall, MP concentrations in the estuarine water increased to 1.8–4.3 pieces/L, and PEPD, in particular, increased significantly, with a proportion of 43%–52%, indicating the contribution of MPs derived from street runoff. Although analyses of molecular markers of sewage, i.e., linear alkylbenzenes and coprostanol, confirmed the input of combined sewer overflow (CSO) to the estuarine water, we did not observe any significant increase in PET fiber MPs, indicating that there was no significant increase in the contribution of MPs from sewage including CSO to the estuarine waters after a rain event. This study highlights the importance of street runoff as a source of MPs in urban aquatic environments. Further investigation should be performed to quantitatively access the individual sources and processes.
Sign in to start a discussion.
More Papers Like This
Quantifying annual microplastic emissions of an urban catchment: Surface runoff vs wastewater sources
Researchers measured the total annual microplastic emissions from an urban river catchment in Japan and compared contributions from wastewater treatment plants versus surface runoff. They found that the catchment released about 269 tons of microplastics per year, with wastewater being the dominant source for smaller particles and surface runoff contributing more larger particles. The study provides one of the first comprehensive annual budgets of urban microplastic emissions, highlighting the scale of the problem.
Comprehensive Understanding of Microplastics Inflow Off the Coast of Funabashi
Researchers conducted continuous monitoring of microplastic (MP) contamination in rivers, sewage, and coastal waters around Funabashi in Tokyo Bay, finding that MP number densities showed high temporal variability and a gradual decreasing trend, with upstream river sources driving contamination that diminished toward the sea as particles settled into bottom sediments, while sewage was also implicated as a contributor to marine MP pollution.
Occurrence, distribution, and possible sources of microplastics in the surface river water in the Arakawa River watershed
Researchers investigated the occurrence, distribution, and potential sources of microplastics in surface river water along the Arakawa River watershed running through the Tokyo Metropolitan area, contributing to data on microplastic contamination in populated urban freshwater systems.
Urban Stormwater Runoff: A Major Pathway for Anthropogenic Particles, Black Rubbery Fragments, and Other Types of Microplastics to Urban Receiving Waters
Researchers quantified microplastics in urban stormwater runoff from 12 watersheds surrounding San Francisco Bay and found concentrations ranging from 1.1 to 24.6 particles per liter, much higher than typical wastewater treatment plant effluent. The study suggests that stormwater runoff is a major and underappreciated pathway for microplastics and other anthropogenic particles to enter urban waterways.
Characterization and comparison of microplastic occurrence in point and non-point pollution sources
Wastewater, stormwater runoff, and surface water samples from multiple catchment types were compared for microplastic content, with PET dominating in urban and non-point sources while rubber from tire wear dominated highway runoff, and particles smaller than 0.5 mm passing through both wastewater and stormwater treatment systems.