苏州市大气CO_(2)和CH_(4)的浓度变化特征及影响因素分析

Analysis of the variation characteristics and influencing factors of atmospheric CO_(2) and CH_(4) concentrations in Suzhou,China

利用2022年苏州市姑苏站大气CO_(2)和CH_(4)浓度及气象观测数据,研究了长三角典型城市苏州市大气CO_(2)和CH_(4)的浓度变化特征以及气象因素和气团输送对CO_(2)和CH_(4)时空变化的影响.结果表明:2022年苏州大气CO_(2)和CH_(4)年平均摩尔分数分别为(449.8±15.2)×10^(-6)和(2108.5±82)×10^(-9),显著高于全球平均浓度和中国本底观测站监测浓度;CO_(2)和CH_(4)浓度日变化均呈双峰特征,除了在早上8:00—9:00左右达到峰值,同时分别在晚间18:00和20:00出现了小高峰,体现了城市人为活动的影响;气象要素中风速与大气CO_(2)和CH_(4)的相关性最大,表现为随着风速增大,扩散增强,CO_(2)和CH_(4)浓度减小;大气CO_(2)和CH_(4)浓度在不同季节都具有明显的相关性,尤其是春季和冬季,说明二者在苏州的排放源或吸收过程可能存在共同的影响因素或机制;在秋季和冬季WNW-SSW扇区大气CO_(2)和CH_(4)浓度较高与该方向居民楼燃料排放和天然气泄漏有关,同时秋冬季节太湖和农田会释放较高浓度的CH_(4).结合后向轨迹和潜在源解析,浙江省宁波市、福建省三明市对苏州市CO_(2)和CH_(4)的贡献率较高,黄海区域分布有较大面积的潜在源区,该海域航海船舶排放会带来高浓度的CO_(2)和CH_(4),且黄海作为天然湿地对CH_(4)浓度具有较大贡献.

This study examined the spatiotemporal variations of atmospheric CO_(2) and CH_(4) concentrations in Suzhou,a typical city in the Yangtze River Delta of China,and explored the impacts of meteorological factors and air mass regional transport on these variations.The observation data of atmospheric CO_(2) and CH_(4) as well as meteorological data collected from Gusu Station of Suzhou during 2022 were utilized.The results revealed that the annual average molar fractions of atmospheric CO_(2) and CH_(4) at Gusu station in 2022 were(449.8±15.2)×10^(-6) and(2108.5±82)×10^(-9),respectively,which were significantly higher than the global average concentrations and those observed at background observation stations in China.The diurnal variations of CO_(2) and CH_(4) displayed bimodal patterns,with peaks occurring in the morning around 8:00—9:00 and smaller peaks appearing in the evening around 18:00 and 20:00,indicating the obvious influence of urban anthropogenic activities.Among various meteorological factors,wind speed exhibited the strongest correlation with atmospheric CO_(2) and CH_(4),with concentrations decreasing as wind speed increased due to enhanced diffusion.In addition,distinct correlations were observed between CO_(2) and CH_(4) concentrations in different seasons,especially in spring and winter,suggesting the potential presence of common influencing factors or mechanisms for emission sources or absorption processes in Suzhou.In autumn and winter,high CO_(2) and CH_(4) concentrations in the WNW-SSW sector were associated with fuel emissions and natural gas leakage from residential buildings.Furthermore,high CH_(4) in the atmosphere was also found to be released from Taihu Lake and farmland.Backward trajectory and potential source analysis showed that the cities of Ningbo in Zhejiang Province and Sanming in Fujian Province contributed significantly to CO_(2) and CH_(4) emissions in Suzhou.The Yellow Sea region featured a substantial area with the potential for emissions,where maritime vessels were identified as significant contributors to elevated concentrations of CO_(2) and CH_(4).Additionally,the Yellow Sea,serving as a natural wetland,played a significant role in the concentration of CH_(4).