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Total gaseous mercury (TGM) and carbon monoxide (CO) were measured every 5min and hourly, respectively, in Seoul, Korea, from February 2005 through December 2006. The mean concentrations of TGM and CO were 3.44±2.13ngm−3 and 613±323ppbv, respectively. TGM and CO concentrations were highest during the winter and lowest during the summer. In total, 154 high TGM concentration events were identified: 86 were classified as long-range transport events and 68 were classified as local events. The TGM and CO concentrations were well correlated during all long-range transport events and were weakly correlated during local events. Five-day backward trajectory analysis for long-range transport events showed four potential source regions: China (79%), Japan (13%), the Yellow Sea (6%), and Russia (2%). Our results suggest that measured ΔTGM/ΔCO can be used to identify long-range transported mercury and to estimate mercury emissions from long-range transport. [Copyright &y& Elsevier]

The increasing global consumption of seafood has led to increased trade among nations, accompanied by mislabeling and fraudulent practices that have rendered authentication crucial. The multi-isotope ratio analysis is considered as applicable tool for evaluating geographical authentications but requires information and experience to select target elements such as isotopes, through a distinction method based on differences in habitat and physiology due to origin. The present study examined recombination conditions of multi-elements that facilitated geographically distinct classifications of the clams to sort out appropriate elements. Briefly, linear discriminant analysis (LDA) analysis was performed according to several combinations of five stable isotopes (carbon (δ13C), nitrogen (δ15N), oxygen (δ18O), hydrogen (δD), and sulfur (δ34S)) and two radiogenic elements (strontium (87Sr/86Sr) and neodymium (143Nd/144Nd)), and the geographical classification results of the Manila clam Ruditapes philippinarum from Democratic People's Republic of Korea (DPR Korea), Korea and China were compared. In conclusion, linear discriminant analysis (LDA) with at least four elements (C, N, O, and S) including S revealed a remarkable cluster distribution of the clams. These findings expanded the application of systematic multi-elements analyses, including stable and radiogenic isotopes, to trace the origins of R. philippinarum collected from the Korea, China, and DPR Korea. [ABSTRACT FROM AUTHOR]

Quantitative estimation for tracking the transport of various nitrate sources is required to effectively manage nitrate loading in complex river systems. In this study, we validated an integrated framework using field isotopic data (δ 15 N NO3 and δ 18 O NO3 ) of nitrates and hydrological modeling (hydrological simulation program FORTRAN; HSPF) to determine anthropogenic nitrate flux among different land-use types within a watershed. Nitrate isotopic compositions showed different ranges among four land-use types (4.9 to 15.5‰ for δ 15 N NO3 , -4.9 to 12.1‰ for δ 18 O NO3 ), reflecting the different nitrate sources (sewage, synthetic fertilizer, effluent and soil) within watersheds. Based on the integration of HSPF modeling, we also found that total nitrate loads might be partially controlled by hydrological conditions such as water discharge (12,040.3-22,793.2 L/s) from upstream to downstream. Among the nitrate sources, the sewage transport showed unique enhancement near urban boundaries, along with an increase in total nitrate load (>193.5 NO 3 -N g/s km 2 ) in downstream areas. In addition, the isotopic- and model-based nitrate fluxes showed good correlation for urban sources (R 2 =0.73, p < 0.05) but poor correlations for agriculture-dominated land use (R 2 =0.13, p > 0.05), reflecting the potential influence of surface runoff and ground infiltration into the watershed. Consequently, this research provided useful information to establish nitrogen management policy controlling point and non-point nitrate source loads in various land-use types for the restoration of water quality and aquatic ecosystem in the complex river system. Considering the recent increase in human activities near aquatic environments, this framework would be effective for individually estimating the quantitative contributions of anthropogenic nitrate sources transported along river-coastal systems., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier Ltd.)