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To clarify the combined effects of O3 and soil salinity on net photosynthetic rate, stomatal conductance, and radical scavenging system of Bangladeshi spring wheat cv. BAW1059, plants were grown in two soil salinity levels (irrigated with 0 and 150 mM NaCl solutions) and exposed to three O3 concentrations [charcoal-filtered air (CF), 1.0-fold the ambient O3 concentration (1.0×O3), and 1.5-fold the ambient O3 concentration (1.5×O3)]. The soil salinity mitigated adverse effects of O3 on net photosynthesis in the 7th and flag leaves. The soil salinity did not induce stomatal closure, indicating no limitation of stomatal O3 uptake. The activities of ascorbate peroxidase and catalase were stimulated by the soil salinity in the 7th and flag leaves, especially under 1.5×O3 concentration. In the flag leaf, the soil salinity induced a significant increase in dehydroascorbate reductase activity and ascorbate concentration. These results suggest that the soil salinity activated detoxification capacity related to mitigation of O3 damage on net photosynthesis in both 7th and flag leaves, while the activated enzymes and antioxidants were different between the leaves. [ABSTRACT FROM AUTHOR]

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Since 1983, the Ministry of the Environment of Japan has conducted nation-wide acid deposition surveys. To investigate the effects of acid deposition on surface water, we used the nonparametric Mann–Kendall test to find temporal trends in pH, alkalinity, and electrical conductivity (EC) in more than 10 years of data collected from five lakes and their catchments (Lake Kuttara: northernmost; Lake Kamakita: near Tokyo; Lake Ijira: central; Lake Banryu: western; and Lake Unagiike: southernmost). The pH of Lake Ijira water has declined slightly since the mid-1990s, corresponding with the downward trends seen in the pH and alkalinity of the river water flowing into the lake. There were significant upward trends in the EC of both the lake and stream water; the same trends were also found for $$ {\text{NO}}^{ - }_{3} $$ concentrations. These trends show evidence of acidification due to atmospheric deposition, and this is the first such finding in Japan based on significant long-term trends. Lake Ijira is located about 40 km north of the Chukyo industrial area near Nagoya. The annual depositions of H+, nss- $$ {\text{SO}}^{{2 - }}_{4} $$ , and $$ {\text{NO}}^{ - }_{3} $$ in Lake Ijira were among the highest of all deposition monitoring sites, suggesting that this is the main cause of the significant acidification observed in Lake Ijira. No significant trends suggesting acidification were observed in any of the other lake catchments in spite of the significant upward trends in EC. Upward trends in pH and alkalinity at Lake Banryu and upward trends in alkalinity at Lake Kamakita were detected, but no change in pH or alkalinity at Lake Kuttara and Lake Unagiike was observed. [ABSTRACT FROM AUTHOR]

The predicted increases in emissions of primary pollutants in many rapidly industrializing countries may have severe consequences for the health and productivity of forest trees and agricultural crops. This paper presents a review of air pollution impacts on vegetation in developing countries by summarising information describing the direct impacts to vegetation caused by a number of air pollutants (sulphur dioxide (SO2), nitrogen oxides (NOx), ozone (O3) and Suspended Particulate Matter (SPM)). This information has been collected by experts from a number of rapidly industrializing countries in Asia, Latin America and Africa and includes observations of visible injury in the field and the use of transect studies and controlled experimental investigations to ascribe damage to different pollutant concentrations. The ability to synthesise this information to define exposure-response relationships and subsequent air quality guidelines similar to those established in North America and Europe is assessed. In addition, the use of regional and global models describing pollution concentrations is discussed with reference to assessing the extent of adverse impacts and identifying regions likely to be most at risk from air pollution, both for the present day and in the future. The evidence summarised in the paper clearly shows that current pollutant concentrations experienced in many developing countries, particularly Asia, can result in severe damage to vegetation and that without appropriate control measures such damage is likely to worsen in the future as pollutant emissions increase. [ABSTRACT FROM AUTHOR]