Astudy on the establishment of environmental standard of photochemical oxidants for protecting plants

本文研究了光化学氧化剂中的主要成分臭氧对日本郊区农作物生长和产量的影响，并对保护植物的环境标准进行了评估。日本关东地区郊区种植的作物对臭氧的生长敏感性和产量敏感性有很大差异。根据O_3对作物产量影响的试验研究结果，认为评价O_3对作物产量影响的最适宜的O_3参数为AOT30(超过30 ppb的累积剂量)。我们建议用1.5ppm/h的AOT30(9：00-16：00)作为保护日本郊区农作物产量的臭氧临界水平。在东京都和崎玉县的大部分地区，7-9月臭氧的AOT30都在1.5ppm/h以上。通过7~9月对小松、青更菜、大头菜、花环菊、大葱等5种作物的臭氧减产效果进行了评价，结果表明，在臭氧浓度和剂量较高的东京都西部和崎玉县北部，5种作物的臭氧减产幅度估计为11-35%。因此，应尽快制定保护植物的光化学氧化剂环境标准。

In the present study, we investigated the effects of ozone (O3), a major component of photochemical oxidants, on growth and yield of crops cultivating in the suburban areas of Japan and evaluated environmental standard for protecting plants. There was great difference in the sensitivity of growth and yield in O_3 among the crops cultivating in the suburban areas of Kanto-district of Japan. Based on the results of experimental study on the effects of O_3 on yield of crops, the most suitable O_3 parameter for evaluating the effects of O_3 on the yield of crops was considered to be AOT30 (accumulated dose over a threshold of 30 ppb of O_3). We propose 1.5 ppm h of AOT30 (9:00-16:00) as critical level of O_3 for protecting the yield of crops cultivating in the suburban areas of Japan. In most areas of Tokyo Metropolis and Saitama Prefecture, AOT30 of O_3 is above 1.5 ppm h from July to September. We evaluated O_3-induced yield reduction of 5 crops (komatsuna, quing-geng-cai, turnip, garland chrysanthemum and welsh onion) from July to September As a result, the O_3-induced reduction rate of the 5 crops was estimated to be 11-35% in the western part of Tokyo Metropolis and northern part of Saitama Prefecture where the concentration and dose of O_3 are relatively high. Therefore, we should establish environmental standard of photochemical oxidants for protecting plants as soon as possible.