## 1 Introduction  
Biomass burning, such as wildfires, biofuel burning, agricultural waste burning, and open field burning, is known to be among the major sources of atmospheric pollutants, including volatile species and airborne particulate matter (PM) [1, 2, 3, 4, 5, 6]. The spatial distribution and chemical composition of airborne PM have attracted the attention of atmospheric scientists for the last two decades due to their relevance to cloud formation, which directly influences the Earth's radiative forcing, as well as to adverse health effects. It has also been reported that wildfires emit gaseous mercury species [7], which account for 8% of total global mercury emissions into the atmosphere [8]. Thus, studying biomass burning emissions can contribute to evaluating the effectiveness of the Minamata Convention on Mercury, which regulates the use of man-made mercury internationally in order to mitigate global mercury pollution. These subjects are intriguing for geoscientists in terms of material cycles in the biosphere. Despite the intensive studies completed on these issues to date, there are still many open questions remaining, such as the source apportionment and fate of atmospheric gaseous mercury and particulate organic carbon. The major difficulty is that the ambient air contains a complex mixture of those species from a variety of emission sources. Thus, concentration measurements alone are limited in providing convincing scientific evidence for their estimation in source contribution studies. To better trace the materials, isotopic compositions of elements, such as stable mercury isotope ratios (denoted as \(\delta^{\rm{3}}\)Hg hereafter), stable carbon isotope ratio (\(\delta^{\rm{13}}\)C), stable nitrogen isotope ratio (\(\delta^{\rm{15}}\)N),and radiocarbon (\({}^{14}\)C) isotope ratio, denoted as percent modern carbon (pMC) hereafter, have been drawing attention, since measurements of isotopic compositions increase the dimensions of the dataset, which allows us to objectively evaluate the mixing state and extent of processing [9; 10; 11; 12; 13; 14; 15; 16; 17]. To accomplish such a goal, knowledge of the initial isotopic compositions of those species at emission are indispensable [18; 19; 20; 21; 22; 23]. To date, however, the reported initial stable isotopic compositions of emission sources are still limited.  
The purpose of our research is to isotopically characterize total gaseous mercury (TGM), particulate low volatile water-soluble nitrogen (LV-WSN), and organic carbon (LV-WSOC) emitted from open field burning, called noyaki in Japanese. Specifically, the aim was to characterize five \(\delta^{\rm{N}}\)Hg of TGM (\(\delta^{\rm{199}}\)Hg, \(\delta^{\rm{200}}\)Hg, \(\delta^{\rm{201}}\)Hg, \(\delta^{\rm{202}}\)Hg, and \(\delta^{\rm{204}}\)Hg), \(\delta^{\rm{15}}\)N of LV-WSN, and \(\delta^{\rm{13}}\)C and pMC LV-WSOC in PM from noyaki in the Aso region. This is a continuation of studies reporting the measurement of TGM emitted from noyaki in 2019 [24]. With additional results from the same study conducted in 2021, the study of nitrogen and carbon in the water-soluble component extracted from airborne PM emitted from noyaki is newly presented.