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Kubota, Tomohiro; Kuroda, Hisao*; Watanabe, Mirai*; Takahashi, Akiko*; Nakazato, Ryoji*; Tarui, Mika*; Matsumoto, Shunichi*; Nakagawa, Keita*; Numata, Yasuko*; Ouchi, Takao*; et al.
Atmospheric Environment, 243, p.117856_1 - 117856_9, 2020/12
Times Cited Count：3 Percentile：15.1(Environmental Sciences)The dry and wet depositions of atmospheric ammonia (NH
) is one of the important pathways of nitrogen loads to aquatic ecosystems. Crop and livestock agriculture, one of the largest emitters of NH in Asian countries, are known to cause high spatial and seasonal variation of NH and influence the surrounding lake basin areas via its dry and wet deposition. However, the spatial characteristics of the NH concentration in basin scale are not completely understood for regulation in NH emission. Here we aim to clarify dominant factors of spatial and seasonal variations of the NH concentration in a eutrophic lake basin surrounded by agricultural areas in Japan. Passive sampling over various land use categories in the basin was conducted at 36 sites in total from October 2018 to January 2020. Interestingly, the observed NH concentration near the livestock houses were higher in winter than summer, which was inconsistent with knowledge of seasonal changes of current NH emission inventory based on temperature-driven volatilization process. Comparing monthly NH concentrations with various meteorological factors, we suggested the importance of seasonal advection of NH from high emission sources to which has been rarely paid attention by the previous past studies. As for this, should be considered for lake ecosystem management since deposition of NH is known to be closely related to the ecological processes such as phytoplankton blooming.
Nakayama, Hiromasa; Katata, Genki
no journal, ,
Dry deposition is the process by which gaseous materials and aerosol particles deposit on the ground surface by turbulence or gravity settling. In Japan, many forest areas are located over hilly complex surface geometries. It is difficult to accurately estimate dry deposition amounts for such areas. To deal with the problems, we have developed a local-scale high-resolution atmospheric dispersion model using Large-Eddy Simulation at a grid scale less than 10m which can consider the turbulent effects of local terrain, buildings, and trees. In this study, we apply this model to the study forest site in the suburbs of Tokyo and investigate the relationship between the structure of the forest canopy and dry deposition amounts, considering the dry deposition process of PM2.5.
Nakayama, Hiromasa; Katata, Genki*
no journal, ,
Dry deposition is important process of chemical material input of gaseous and particulate forms from the atmosphere into the terrestrial ecosystem near the ground surface in the planetary boundary layer. It is difficult to accurately estimate dry deposition amounts for such areas. First, we incorporate our particle dry deposition scheme into the loca-scale high-resolution atmospheric dispersion model and perform test simulations in comparison to indoor experiments. Next, we apply to the hilly-terrain forest in a field-site to analyze the impact of topography and forest structure to dry deposition. It is found that the model successfully simulated the maximum values at the edge of the forest and exponential decrease with a downwind distance from the edge as well as the experiments. Furthermore, for the field-site, the distribution of dry deposition shows a peak at the forest edge, rapidly decreases with a downwind distance from the edge. Although the local decrease is observed at the forest gap, that shows nearly constant within the canopy.
Katata, Genki*; Kubota, Tomohiro; Kuroda, Hisao*; Watanabe, Mirai*; Takahashi, Akiko*; Nakazato, Ryoji*; Tarui, Mika*; Matsumoto, Shunichi*; Nakagawa, Keita*; Numata, Yasuko*; et al.
no journal, ,
no abstracts in English
