Vertical gradient of needle ozone uptake within the canopy of Cryptomeria japonica.

Leaf ozone uptake through the stomata is an important index for the ozone risk assessments on trees. Stomatal conductance (g) and ozone concentration ([O]), determinants of the leaf ozone uptake, are known to show vertical gradients within a tree canopy. However, less is known about the within-canopy vertical gradient of leaf ozone uptake.

Stomatal ozone uptake of a Quercus serrata stand based on sap flow measurements with calibrated thermal dissipation sensors.

The amount of ozone absorbed by the tree leaves is a critical factor determining the ozone effects on forest trees. Stomatal ozone uptake of a forest canopy can be estimated from the ozone concentration and canopy conductance (g) determined by the sap-flow-based method. This method measures sap flow as a metric of crown transpiration and then derives g.

Disentangling the contribution of the transboundary out-flow from the Asian continent to Tokyo, Japan.

We assessed the contribution of transboundary air pollutants (TAPs) transported from China to Tokyo using the Pb/Cu index. We conducted intensive observations over four seasons during 2014-2015 and analyzed ionic components and thirteen elements in size-segregated aerosols collected at the top of a 30-m-high tower in a hilly forested area of the Field Museum Tamakyuryo (FM Tama), in a western suburb of Tokyo. In order to evaluate if the Pb/Cu ratio can be applied in Tokyo as the megacity, the annual average concentration of Pb at Cape Hedo, Kumamoto city, on the west side of Japan, was higher than that of Pb at Tokyo, on the east side; this result indicates that TAPs affect western Japan more than eastern Japan.

Trends of sulfur and nitrogen deposition from 2003 to 2017 in Japanese remote areas.

Emissions of sulfur (S) and nitrogen (N) compounds in East Asia has drastically changed over the last two decades. To assess the influence of the drastic changes in air pollution on ecosystems in Japan, we investigated the trends of S and N deposition during 2003-2017 at remote sites of Acid Deposition Monitoring Network in East Asia (EANET). We measured wet deposition and inferentially estimated dry deposition of S and N using monitoring data from 2003 to 2017 at eight sites.

Nitrogen burden from atmospheric deposition in East Asian oceans in 2010 based on high-resolution regional numerical modeling.

East Asian oceans are possibly affected by a high nitrogen (N) burden because of the intense anthropogenic emissions in this region. Based on high-resolution regional chemical transport modeling with horizontal grid scales of 36 and 12 km, we investigated the N burden into East Asian oceans via atmospheric deposition in 2010. We found a high N burden of 2-9 kg N ha yr over the Yellow Sea, East China Sea (ECS), and Sea of Japan.

Aerosol Liquid Water Promotes the Formation of Water-Soluble Organic Nitrogen in Submicrometer Aerosols in a Suburban Forest.

Water-soluble organic nitrogen (WSON) affects the formation, chemical transformations, hygroscopicity, and acidity of organic aerosols as well as biogeochemical cycles of nitrogen. However, large uncertainties exist in the origins and formation processes of WSON. Submicrometer aerosol particles were collected at a suburban forest site in Tokyo in summer 2015 to investigate the relative impacts of anthropogenic and biogenic sources on WSON formations and their linkages with aerosol liquid water (ALW).

[Investigation of a CT value electron density conversion method in radiotherapy planning CT].

To obtain heterogeneous corrections, it is necessary to convert computed tomography (CT) values into electron density. However, differences in the current conversion tables of the method of acquisition for each institution are not clear. Therefore, we sent a questionnaire survey to 200 radiotherapy institutions in the Kanto area regarding heterogeneous correction data acquisition.