Insights into national distribution of NH3 concentrations in Republic of Korea: findings from passive sampler observations and implications for sources and management.

Gas-phase NH3 is one of the significant contributors to secondary aerosol formation in the atmosphere, and it is a crucial consideration in any strategy aiming to reduce PM2.5 emissions. This study aimed to investigate the spatial distributions of NH3 in verity source areas in Republic of Korea using passive samplers. NH3 concentrations were observed at 45 locations over a period of approximately 35 weeks, from June 2022 to February 2023. As a result, NH3 concentration was found to be more affected by local sources rather than long-distance influx from outside. The average concentration of NH3 observed in 7 source areas excluding the background area was all less than 20.91 ppb, except for livestock sources. These results suggest that atmospheric NH3 concentrations are significantly influenced from livestock sources. In addition, in major cities, the need for NH3 management was confirmed to be more focused on emissions from automobiles and industrial complexes than emissions from livestock and farmland. Moreover, even for the same source, NH3 concentrations varied depending on the type of livestock species, breeding methods and scale, products produced, crops cultivated, and vehicle traffic volume. These findings indicate the importance of considering factors such as breeding methods and manure treatment practices in emission factors, and it is expected that the results can be used as basic data for NH3 emission estimation and management.

Effects of Tributyltin-Contaminated Aquatic Environments and Remediated Water on Early Development of Sea Urchin (Hemisentrotus pulcherrimus).

In this study, gametotoxicity and embryotoxicity experiments were performed using Hemicentrotus pulcherrimus to investigate the toxic effects of tributyltin (TBT). The effects of TBT on fertilization and embryogenesis were assessed at various concentrations (0, 0.02, 0.05, 0.09, 0.16, 0.43, 0.73, 4.68, and 9.22 ppb). The fertilization rates decreased in a concentration-dependent manner, with significant reduction following treatment with TBT at 0.05 ppb. Embryos exhibited developmental impairment after TBT exposure at each tested concentration. The frequency of developmental inhibition delay that treatment with TBT delayed embryonic development in a dose-dependent manner, with 100% of embryos exhibiting developmental impairment at 4.68 ppb. During developmental recovery tests, embryos cultured in fresh media without TBT showed advanced embryonic development. Although the observed normal development after transferring the developmentally delayed embryos to fresh media without TBT offers prospects for the restoration of contaminated environments, embryonic development remained incomplete. These results suggest that TBT adversely affects the early embryonic development of H. pulcherrimus.