Assessment on the effects on ecosystems and the environment

Title of Research:
19_R05-01
Establishment of medaka kinetic model for aged microplastic and adsorbed chemical

Principal Investigator:
Yuji Oshima (Kyushu University, Faculty of Agriculture, Laboratory of Marine
Environmental Science Professor)
744 Motooka, Nishi-ku, Fukuoka 8020345, Japan(tel&fax)+81-092-802-4607

Collaborators:
Yohei Shimasaki (Faculty of Agriculture, Kyushu University, Associated Professor)
Kang Ik Joon (School of Interdisciplinary Science and Innovation, Kyushu University,Associated Professor)

Summary of Research:
Plastic has extensive use in our daily life due to its low cost, lightweight, and hard todecompose. Due to their high production and slow degradation, plastic pollution has
expanded worldwide in aquatic environments. Pollution of plastic from large items to small
particles (microscopic plastic MP, < 5mm) emerged. The effect of MP and its vector effectwith pollutants are of concerns. Many researchers have studied these topics. However,most of study were used pristine MPs. Thus, the study on effect of aging on vector effect ofMP is required.
First, commercially available polyethylene pellets were used to produce grind
polyethylene microplastics (ｃgPE-MP, 200 µm), and then this MP was aged by exposure toUV irradiation equivalent to 5 years in a real environment (aｃgPE-MP).
Next, effect of aging on anthracene (ANT) uptake on medaka fish was examined using thecgPE-MP and acgPE-MP. No apparent difference was observed in ANT concentrations offish between cgPE-MP and acgPE-MP co-exposure treatments. This result might be
attributed to decrease of ANT concentration in water phase caused by absorption of ANTto cgPE.
The results of a follow-up test using sphere PE-MP (sPE-MP) and cgPE-MP showedthat the concentration of ANT in the water was reduced to 87% and 73%, respectively.
Simulation results showed a vector effect of sPE-MP and cgPE-MP co-exposure group.
3-year studies have confirmed the vector effect on ANT for PE and PS-MP(approximately 200 µm, 40 mg/L). There seemed to be no significant difference in vector
effect due to shape (sphere or grind) or aging. The cPE-MP also showed that it could
strongly bind to ANT in water and reduce ANT concentration in the fish.
Furthermore, a PE-MP-ANT dual one-compartment model was constructed to predict
vector effect in real environment, and it was estimated that the vector effect would beapparent at high MP concentrations (40 mg/L), but that the vector effect on ANT would be
weak at low MP concentrations (0.1 mg/L, similar to the real environment). In the future
work, it is necessary to construct vector effect prediction model that considers MP quality,

Assessment on the effects on ecosystems and the environment
particle size, vector chemicals.

Timeline:
March 1, 2019 - Feb 1, 2022

Topics:Publications:
1) Qiu, X., Saovany, S., Takai, Y., Akasaka, A., Inoue, Y., Yakata, N., Liu, Y., Waseda,
M., Shimasaki, Y., Oshima, Y., 2020. Quantifying the vector effects of polyethylene
microplastics on the accumulation of anthracene to Japanese medaka (Oryzias
latipes). Aquatic Toxicology 228, 105643.
2) Assas, M., Qiu, X., Chen, K., Ogawa, H., Xu, H., Shimasaki, Y., Oshima, Y., 2020.
Bioaccumulation and reproductive effects of fluorescent microplastics in medaka
fish. Mar. Pollut. Bull. 158, 111446.
3) Liu, Y., Qiu, X., Xu, X., Takai, Y., Ogawa, H., Shimasaki, Y., Oshima, Y., 2021.
Uptake and depuration kinetics of microplastics with different polymer types andparticle sizes in Japanese medaka (Oryzias latipes). Ecotoxicol. Environ. Saf. 212,112007.