2024 Volume 47 Issue 4 Pages 105-112
Toward conducting ecological risk assessments (particularly exposure assessments) that consider the unique characteristics of microplastic particles (MPs) , there are methods for estimating the concentration of MPs, including the unmeasured size range, as well as concentration conversion methods. We aimed to apply these methods to the data measured at the Tokyo Bay area. First, we described the rescaling method for estimating the size distribution of MPs, including the unmeasured size range, by fitting the measured data of MPs collected from the surface water of the Tsurumi River estuary in Tokyo Bay to a continuous power law distribution. Then, we applied the rescaling method to the data measured at Tokyo Bay and estimated the number concentrations of MPs, incorporating the unmeasured size range. In addition, on the basis of the data measured at the Tsurumi River estuary, we showed the conversion of number concentrations to weight, volume, and surface area concentrations, which are often used in hazard assessments, suggesting that the order of concentration levels between sites may change depending on the concentration unit used. On the basis of these results, we discussed the issues on these rescaling and unit conversion methods.
