长三角地区春季臭氧污染特征及其对冬小麦产量的影响

春季是长三角地区对流层O₃污染的高峰期之一，高浓度的O₃暴露会影响冬小麦生长导致减产.利用长三角地区各城市2014年春季逐时ρ（O₃）观测数据，研究了长三角地区春季O₃污染特征，并结合O₃暴露指数（M7指数和AOT40指数）和剂量-响应关系模型，详细评估了长三角地区O₃污染对冬小麦产量的影响.结果表明:长三角地区春季ρ（O₃）空间上总体呈南低北高的分布，长三角地区北部江苏和上海的ρ（O₃）明显高于南部的浙江地区，在浙江北部、江苏和上海等地区，整个春季日最大8 h ρ（O₃）平均值超过107 μg/m3，最高值出现在5月，超过128 μg/m3；一半以上的城市ρ（O₃）超标[超过GB 3095-2012《环境空气质量标准》中8 h滑动平均ρ（O₃）的二级标准限值（160 μg/m3）]日数在10 d以上，其中南京和扬州超标日数最多，分别为27和20 d；相应地，O₃暴露指数也呈南低北高的分布，其中苏北地区O₃暴露指数最高，导致长三角地区平均冬小麦相对损失达5.7%（M7）~25.5%（AOT40），造成的产量损失为7.85×105 t（M7）~4.49×106 t（AOT40），其中，苏北地区为5.8%（M7）~25.9%（AOT40），造成的产量损失为6.77×105 t（M7）~3.86×106 t（AOT40），占长三角地区冬小麦产量损失的86%以上.研究显示，当前长三角地区O₃污染及其对冬小麦产量的影响已相当严重，特别是对苏北地区，而苏北地区是我国重要的冬小麦产地之一，因此，应当科学有效地治理O₃污染以缓解粮食安全问题. 

Characteristics of Ozone Pollution and Its Impact on Winter Wheat Yield in the Yangtze River Delta in Spring

Spring is one of the peak periods for surface ozone (O₃) pollution in the Yangtze River Delta (YRD). High O₃ exposure could bring great harm to winter wheat growth so as to reduce its yield. Based on hourly O₃ measurements in each city over the YRD and O₃ exposure indexes (M7 and AOT40) as well as a dose-response model, we studied the characteristics of ozone pollution and evaluated the O₃ impact on the yield of winter wheat in the spring of 2014. There was a decreasing trend from the north to the south for the spatial distributions of O₃ concentrations in the YRD, i.e., the O₃ concentrations over the north YRD including Jiangsu Province and Shanghai were significantly higher than those over Zhejiang Province. In Jiangsu Province, Shanghai and northern Zhejiang Province, the highest seasonal mean daily maximum 8-hour O₃ concentrations exceeded 107 μg/m3. There were highest concentrations in May, with mean value exceeding 128 μg/m3. In half of the YRD cites, there were more than 10 days with the O₃ concentrations exceeding the China national standard (160 μg/m3), in which Nanjing and Yangzhou cities had the maximum number of days exceeding the standard, with values of 27 and 20 days, respectively. Accordingly, the O₃ exposure indexes in the northern YRD were also higher than those in the southern area. The highest indexes were located in northern Jiangsu Province. The O₃ exposure caused an average relative yield loss of winter wheat of about 5.7% (based on M7) to 25.5% (based on AOT40), and a mean yield loss of 7.85×105 t (M7) to 4.49×106 t (AOT40) in the YRD region. In particular, in northern Jiangsu Province, the mean relative yield loss rate reached 5.8% (M7) to 25.9% (AOT40), and the corresponding yield loss was 6.77×105 t to 3.86×106 t, which accounted for more than 86% of the whole yield loss in the YRD. This indicated that the current O₃ pollution and its impacts on winter wheat in the YRD region was quite serious, especially in northern Jiangsu Province-one of the most important winter wheat producing area in China. Therefore, it is time to control the O₃ pollution to alleviate the pressure on food security.