Long-term trends from FY1998 to FY2012 were analyzed using the component concentrations of gas–aerosols in Fukuoka Prefecture. These data were then compared to those of wet depositions. The average concentrations of nss-SO₄^2-, T-NO₃ (=NO₃^-₊HNO₃), NH₄⁺, and nss-Ca²⁺in the gas–aerosols were 64.2 nmol/m³, 74.7 nmol/m³, 108 nmol/m³, and 15.6 nmol/m³, respectively, and showed high concentrations in spring, as well as the photochemical oxidants (Ox). Comparing the annual variation (three-year moving average) of the component concentrations in the gas–aerosols with those of the wet depositions, both nss-SO₄^2- and T-NO₃ showed upward trends after FY2000, then began those of the wet depositions to decrease after a peak in approximately FY2007. The T-NO₃/nss-SO₄^2- equivalent ratio in the gas–aerosols gradually decreased after FY2000 but switched to an upward trend after approximately FY2008. Conversely, the NO₃^-/nss-SO₄^2- equivalent ratio in the wet depositions showed a tendency to increase year by year. The NH₄⁺concentration in the gas–aerosols and wet depositions showed the same trend as nss-SO₄^2-. The nss-Ca²⁺reflected the influence of yellow sand, particularly in the wet depositions.

It is considered that the effect of the transport of pollutants from East Asia to northern Kyushu is decreasing because nss-SO₄^2-, T-NO₃ (NO₃^-) and nss-Ca²⁺in both the gas–aerosols and wet depositions have exhibited a slightly downward trend since approximately FY2008.

The inorganic element composition of 25 filter products for PM_2.5 sampling was determined by acid digestion and ICP-MS. The Filter materials were PTFE, quartz fiber, cellulose, and polycarbonate. Each filter’s method blank (MBlk) and method quantify limit (MQL) were calculated and compared with the target quantify limit (TQL) for the PM_2.5 inorganic element analysis by the Ministry of the Environment, Japan. Depending on the products, the PTFE filters showed a higher MBlk than TQL for Ca, Ti, Fe, Sb, and Ta. The higher MBlk than TQL involved 15 elements for the quartz fiber filters, Ca for the cellulose filters, and Cr for the polycarbonate filters. Additional elements with a higher MBlk than TQL depending on products were 6 for the quartz fiber filters, 8 for the cellulose filters, and 1 for the polycarbonate filters. Information in this report would be valuable for an operator’s choice of the PM_2.5 sampling filters. It would also lead to quality improvement of the PM_2.5 inorganic element analysis.

Ground level ozone is a major threat to both agricultural crops and forest trees on a global scale. Ozone is absorbed by a plant through the stomata in the leaves, dissolves in the cell wall liquid, and reaches the cell membrane and cytosol, where it oxidizes various cellular components, thus exhibiting a toxicity to plant tissues. The cell wall (or apoplastic) liquid contains ascorbic acid (an aggregate of both neutral ascorbic acid without an electric charge and ionic ascorbate), which, as an antioxidant, serves as the first barrier against the oxidative ozone attack. Plöchl et al. (Planta, 210, 454–467 (2000)) proposed a mathematical model of the ozone detoxification by ascorbate (ASC^-) located in the cell wall. Their model describes (1) diffusive transfer of ozone from the free air to cytosol and concomitant reactions in the apoplast; (2) regeneration of ASC^- from dehydroascorbic acid (a product of ascorbic acid reacted with ozone) in the cytosol and replenishment to the apoplast; and (3) pH-dependent distribution of ASC^- in sub-cellular components. We reviewed the mathematical formula proposed by Plöchl et al. (2000) and corrected some errors in the original paper.

Following the description in the preceding paper of the mathematical model to calculate the detoxification of ozone by ascorbic acid in the apoplast (cell wall), we describe in this paper our implementation of the model using Microsoft Excel. While we collected various parameters of the model from the literature, little information was available about the resistance (ρ₃) to inword ozone transport at plasmalemma (cell membrane). Therefore, we assumed two cases; i.e., “ρ₃=0” and “ρ₃ ≠ 0” in the calculation of the ozone detoxification. The ozone concentration ([O₃]) at the plasmalemma has often been assumed to be zero, which is equivalent to the assumption, “ρ₃=0”. In this case, ascorbate (ASC^-) in the apoplast can detoxify ozone by 35.2%, whereas the remaining 64.8% of the ozone reaches the cytoplasmic membrane and cytosol to react with biological molecules causing subsequent damage. By comparison, the assumption, “ρ₃≠0”, leads to a higher detoxification rate, e.g., 64.5% in the case of ρ₃=80.18 s m^-1 and ambient [O₃] of 100 ppb. The detoxification rate increases as the ambient [O₃] declines, which is consistent with the common notion of a threshold concentration in the ozone damages to plant tissues.