2005-2015年中国及境内典型城市群甲醛柱浓度时空变化及影响因子分析

Spatial-temporal variations and affecting factors of formaldehyde column density over China and typical city groups during the period of 2005—2015

基于2005-2015年OMI反演的甲醛柱浓度月均数据,对中国及境内典型城市群甲醛柱浓度时空变化及影响因子进行了分析.结果发现,甲醛柱浓度高值区集中在京津冀中南部、山东西部、河南北部、江浙沪、珠三角、湖北东部、湖南东部、广西、四川与重庆交界.2005-2015年中国甲醛柱浓度总体呈上升趋势,其中,京津冀地区增长趋势最明显,江浙沪地区呈略微下降趋势.中国、京津冀及江浙沪地区夏季甲醛柱浓度明显高于其余3个季节,呈明显的周期性变化;2005-2015年中国4个季节甲醛柱浓度均呈增加趋势,京津冀地区除夏季外其余3个季节也呈增加趋势,江浙沪和珠三角地区各季节甲醛柱浓度变化趋势不一致.近11年,中国、京津冀和江浙沪地区7月甲醛柱浓度最高,珠三角地区9月甲醛柱浓度最高.京津冀和江浙沪地区甲醛柱浓度月最高值和月最低值之间的差异大于珠三角地区.中国、京津冀、江浙沪和珠三角地区近11年秸秆焚烧与相应甲醛柱浓度呈明显正相关,相关系数为0.84~1.00,表明秸秆焚烧是影响近11年甲醛柱浓度变化的重要因子.尽管有些区域季节温度与相应甲醛柱浓度呈负相关,但温度总体也是影响中国及这3个典型城市群甲醛柱浓度变化的另一个重要因子,京津冀地区尤其明显.月平均温度与相应甲醛柱浓度的相关系数为0.52~0.85.人口、民用汽车保有量和国内生产总值与中国、京津冀、江浙沪和珠三角地区相应甲醛柱浓度相关系数均低于0.60.影响因子分析结果暗示控制秸秆焚烧和减少温室效应是降低我国甲醛柱浓度的重要途径.

We analyzed spatial-temporal variations and affecting factors of formaldehyde column density over China and typical city groups during the period of 2005—2015. The data is from monthly products retrieved by OMI instrument onboard the Aura satellite. The results were listed as follows: The high formaldehyde column density concentrated in the south of Beijing-Tianjin-Hebei(BTH), the west of Shandong, the north of Henan, the Jiangsu-Zhejiang-Shanghai(JZS), the Pearl River Delta(PRD), the east of Hubei, the east of Hunan, Guangxi, and the border between Sichuan and Chongqing. An increasing trend of formaldehyde column density across China, over BTH and PRD and a slight downward trend over JZS from 2005 to 2015 were shown. The increasing trend in BTH was the most distinct. The formaldehyde columns in summer over China, BTH and JZS were significantly higher than those in other three seasons. An increasing trend of formaldehyde column density in 4 seasons in China during the period of 2005—2015 were found. Besides summer, formaldehyde column density in the other 3 seasons over BTH also increased. However, the trends of formaldehyde columns over JZS and PRD were inconsistent among the 4 seasons. The highest monthly formaldehyde column density was seen in July in China, BTH and JZS, and in September in PRD. The difference between the highest and lowest monthly formaldehyde column density over BTH and JZS was greater than that over PRD. During the period 2005—2015, the formaldehyde column density in China and 3 typical city groups was positively correlated with the crop straw burning,with correlation coefficient ranges from 0.84 to 1.00. The high correlation coefficient indicted that the crop straw burning played a crucial role in determining the trend of formaldehyde column density from 2005 to 2015. The mean temperature was also another important factor influencing the variation of formaldehyde column density in China and 3 typical city groups, especially for BTH, although it negatively correlated with the corresponding formaldehyde column density in some regions. The correlation coefficients of the population, civil automobile holding quantity, gross domestic product with the formaldehyde column density in China, BTH, JZS and PRD were all lower than 0.60. The analysis of influencing factors suggested that control crop straw burning and reduce greenhouse effect are important ways to reduce the formaldehyde column density in China.