Table 1.
Altitudes of study sites, collection dates of snow samples, filtered volumes of melted snow samples, the numbers of particles (> 30 µm) on filters, and abundances of MPs (> 30 µm).
| Sample code | Altitude (m a.s.l.) | Collection date | Filtered vol (mL) | Number of particles (particles/filter) | Microplastic abundance (particles/L) |
|---|---|---|---|---|---|
| Bihoro Pass | 505 | 20 Mar. 2021 | 139.4 | 1.6 × 103 | 2.0 × 103 |
| Asahidake [1] | 1674 | 23 Mar. 2022 | 147.9 | 3.8 × 102 | 1.7 × 102 |
| Asahidake [2] | 171.5 | 4.3 × 102 | 1.5 × 102 | ||
| Shiretoko-Goko Lakes | 216 | 13 Jan. 2023 | 200.3 | 4.4 × 102 | 1.9 × 102 |
| Kushiro Shitsugen | 5 | 17 Jan. 2023 | 173.4 | 7.2 × 102 | 5.0 × 102 |
| Lake Onneto | 640 | 22 Jan. 2023 | 208.6 | 1.2 × 103 | 7.4 × 102 |
| Lake Tofutsu | 1 | 04 Feb. 2023 | 177.8 | 6.4 × 102 | 3.1 × 102 |
| Mikuni Pass [1] | 1143 | 05 Feb. 2023 | 159.8 | 8.3 × 102 | 9.6 × 102 |
| Mikuni Pass [2] | 153.6 | 8.0 × 102 | 8.2 × 102 | ||
| Kitami_KIT | 93 | 09 Jan. 2021 | 182.0 | 1.3 × 103 | 1.4 × 103 |
| Kitami_RB [1] | 57 | 19 Jan. 2023 | 233.1 | 4.3 × 103 | 4.0 × 103 |
| Kitami_RB [2] | 218.4 | 4.5 × 103 | 4.2 × 103 |
Numbers in square brackets signify replicates.