## 2 Method and Materials
### Sampling  
Samples collected in the series of noyaki studies were summarized in Supplementary Table S1. Noyaki sampling was carried out at two locations, Daikanpou and Namino, in spring 2019, as well as in three locations, Komezuka, Ubuyama, and Kitayama, in spring 2021 (Figure 1c). TGM and PM emitted from noyaki were sampled from the car window (Figure 3). The car was moved and stopped repeatedly in the downstream of the noyaki plume so that the emissions could be directly captured while a safe distance from the fire could be maintained. The sampling device consisted of an open-face filter holder (Innovation nilu AS, Kjeller, Norway) with a 47 mm o.d. polytetrafluoroethylene (PTFE) coated glass filter (Pallflex, Emfab, Pall Corp., Port Washington, NY, USA), 1/2 inch o.d. \(\times\) ~60 cm long perfluorosiloxy alkane (PFA) tubing (Tombo 9003-PFA, Nichias Corp., Tokyo, Japan), a newly developed big gold mercury trap (BAuT) ([PERSON] et al., 2020), a float flow meter (RK230, KOFLOC, Kyoto, Japan), and a sampling diaphragm pump (N860 FTE, KNF, Freiburg, Germany). PTFE connectors for the BAuT were specially manufactured (COSMOS VID, Fukuoka, Japan), and other standard size connectors used were either PFA (Swagelok, Solon, OH, USA) or PTFE (Flowell 30 series, Flowell Corp., Yokohama, Japan) connectors. An uninterrupted power supply (SURTA1500 XLJ, American Power Conservation, West Kingston, RI, USA) was used as the power source for the diaphragm pump. TGM samples collected using the BAuT setup were summarized in Supplementary Table S2.  
For the noyaki sampling conducted at Ubuyama, Kitayama in 2021, as well as all background air sampling conducted in 2021, double BAuT sampling (TGM sampling using two BAuTs connected in series; the setup is shown in Figure 3) was conducted to monitor breakthrough TGM from the front BAuT. TGM in the air was also sampled using commercially available gold-coated sand traps (4 mm \(\times\) 160 mm; Nippon Instruments Corp., Osaka, Japan) with a mini pump (MP-W5P, SIBATA, Scientific Technology Ltd., Souka, Japan) to compare BAuT and regular TGM sampling. It should be noted that this comparison was made only for the study completed in 2021, due to the sampling and measurement failure of samples collected in 2019. It should also be noted that the PTFE filter was replaced at a certain point during the BAuT sampling, as it was heavily loaded with PM. In addition, stand-alone filter sampling was occasionally conducted separately from the BAuT sampling in order to collect more filter samples.  
Figure 1: Map of (**a**) Japan, (**b**) Kyusyu, and (**c**) Aso region with sampling locations (yellow circles). Courtesy of Geospatial Information Authority of Japan, which permitted the use of GSI maps.  
Noyaki sampling was successfully carried out twice in spring 2019 and three times in 2021. Overall, 2 BAuT samples for TGM and 10 filter samples for water-soluble particulate species were collected during 2019, and 3 BAuT samples and 5 filter samples were collected during 2021 (Supplementary Tables S2 and S3). In addition to the noyaki samples, background air sampling was performed to see the impact from noyaki. Two BAuT background air samples and two background filter samples were collected in 2019, and two BAuT samples and five filter samples were collected in 2021. In addition, _Miscanthus sinensis_ and _Pleiblastus chino_ var. _viridis_ samples were collected from the waste of mown grass in 2021 for \(\delta^{13}\)C analysis.