Assessment of the sources and inflow processes of microplastics in the river environments of Japan

Kataoka, Tomoya; Nihei, Yasuo; Kudou, Kouki; Hinata, Hirofumi

doi:10.1016/j.envpol.2018.10.111

Cited by 397 publications

(160 citation statements)

References 43 publications

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“…Similar trends have been confirmed by other studies [32,33]. In a previous study [40], we found a significant correlation between the MicP contamination in rivers and basin characteristics (here, the population density and the urban area ratio, i.e., the ratio of urbanized to all areas), based on survey results from 29 rivers and 35 locations in Japan. A significant correlation between the MicP contamination in rivers and water quality (biochemical oxygen demand, BOD) was also indicated.…”

Section: Introductionsupporting

confidence: 91%

“…Here, we describe the observational and analytical methods used to measure MicP concentrations in rivers in order to derive correlations with land area data (Step 1). Our methods related to determining MicP concentrations were essentially the same as those of Kataoka et al [40]. As shown in Figure 2, the observation sites included 70 rivers and 90 sites across Japan.…”

Section: Field Sitesmentioning

confidence: 99%

“…When this was converted into an area, 5-10% of the opening area was above the surface. Therefore, the amount of water filtered was underestimated [40]. Since it was not easy to completely control the installation height from the bridge, these errors were ignored in our calculations.…”

Section: Measuring Micp In Riversmentioning

confidence: 99%

“…Since it was not easy to completely control the installation height from the bridge, these errors were ignored in our calculations. Further details of the other observational methods are provided in Kataoka et al [40].…”

Section: Measuring Micp In Riversmentioning

confidence: 99%

“…Since plastic pollution has become a problem in the oceans, many surveys of marine MicP have been conducted [24][25][26][27][28][29]. Following the studies on MicP in the oceans, the number of studies on MicP in rivers and lakes has also increased [30][31][32][33][34][35][36][37][38][39][40]. For example, Yonkos et al [34] measured the MicP concentrations in four rivers that flow into the Chesapeake Bay in Virginia, USA, and showed that MicP contamination in rivers was related to population density and urbanization.…”

Section: Introductionmentioning

confidence: 99%

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High-Resolution Mapping of Japanese Microplastic and Macroplastic Emissions from the Land into the Sea

Nihei

Yoshida²,

Kataoka

et al. 2020

Water

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Plastic debris presents a serious hazard to marine ecosystems worldwide. In this study, we developed a method to evaluate high-resolution maps of plastic emissions from the land into the sea offshore of Japan without using mismanaged plastic waste. Plastics were divided into microplastics (MicPs) and macroplastics (MacPs), and correlations between the observed MicP concentrations in rivers and basin characteristics, such as the urban area ratio and population density, were used to evaluate nationwide MicP concentration maps. A simple water balance analysis was used to calculate the annual outflow for each 1 km mesh to obtain the final MicP emissions, and the MacP input was evaluated based on the MicP emissions and the ratio of MacP/MicP obtained according to previous studies. Concentration data revealed that the MicP concentrations and basin characteristics were significantly and positively correlated. Water balance analyses demonstrated that our methods performed well for evaluating the annual flow rate, while reducing the computational load. The total plastic input (MicP + MacP) was widely distributed from 210–4776 t/yr and a map showed that plastic emissions were high for densely populated and highly urbanized areas in the Tokyo metropolitan area, as well as other large urban areas, especially Nagoya and Osaka. These results provide important insights that may be used to develop countermeasures against plastic pollution and the methods employed herein can also be used to evaluate plastic emissions in other regions.

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Section: Introductionsupporting

confidence: 91%

Section: Field Sitesmentioning

confidence: 99%

Section: Measuring Micp In Riversmentioning

confidence: 99%

Section: Measuring Micp In Riversmentioning

confidence: 99%