春季东海海水和大气中挥发性卤代烃的分布特征研究

挥发性卤代烃（VHCs）是大气中一类重要的痕量温室气体和臭氧破坏者。于2017年5月对东海海水及大气中CFC-11（CC1₃F）、CFC-12（CC1₂F₂）、CFC-113（CC1₂FCC1F₂）和CH₃I的浓度进行了同步测定，讨论了4种VHCs浓度水平分布规律及其影响因素，并估算了CFC-11、CFC-12和CH₃I的海-气通量。结果表明，表层海水中CFC-11、CFC-12、CFC-113和CH₃I浓度平均值分别为（8.1±5.1）、（3.9±1.6）、（10.4±2.3）和（6.3±2.7）pmol/L。VHCs浓度高值出现在东海东北部和闽浙沿岸海域，显著受水团、生物活动及人类活动等因素的影响。相关性分析发现海水中CH₃I浓度与Chl a浓度之间存在显著性相关关系（r=0.403，p < 0.01），说明CH₃I浓度分布可能主要受浮游植物生产释放的影响。大气中CFC-11、CFC-12、CFC-113和CH₃I的浓度平均值分别为（9.8±1.0）、（21.1±2.4）、（3.0±0.9）和（0.2±0.2）pmol/L。结合气象参数（风速和风向）和后向轨迹模拟计算分析可得，陆源污染气团的输送、外海气团的扩散和海-气交换是影响大气中VHCs浓度分布的重要因素。海-气通量的估算结果表明春季东海是大气中CFC-11和CFC-12的汇，是CH₃I的源。

Distributions of volatile halocarbons in seawater and atmosphere in the East China Sea during spring

Volatile halocarbons (VHCs) are important greenhouse gases and ozone depleting substances in the atmosphere.The concentrations of CFC-11 (CC1₃F), CFC-12 (CC1₂F₂), CFC-113 (CC1₂FCC1F₂) and CH₃I in the seawater and marine atmosphere of the East China Sea were measured in May 2017.The spatial distribution of the four kinds of VHCs, their influencing factors and sea-to-air flux were investigated.The mean concentrations of CFC-11, CFC-12, CFC-113 and CH₃I were (8.1±5.1), (3.9±1.6), (10.4±2.3) and (6.3±2.7) pmol/L, respectively.The elevated concentrations of VHCs in the surface water were observed in the northeast of East China Sea as well as on the Fujian and Zhejiang coast area.The results indicated that the distributions of the four kinds of VHCs were influenced by the water mass, biological activities as well as human activities.A positive correlation was found between the concentrations of CH₃I and Chl a in seawater (r=0.403, p < 0.01).The result implied the influence of the production by phytoplankton to concentration distributions of CH₃I in the study area.The mean concentrations of CFC-11, CFC-12, CFC-113 and CH₃I in marine atmosphere were (9.8±1.0), (21.1±2.4), (3.0±0.9) and (0.2±0.2) pmol/L, respectively.Combined with meteorological parameters such as wind velocity and wind direction and back trajectory simulations, the transfer of air terrestrial pollutants from China land, the diffusion of offshore air masses and the exchange of VHCs between sea and air were important factors influencing the concentration distribution of VHCs in the atmosphere.The sea-air flux demonstrated that the East China Sea acted as a sink for atmospheric CFC-11 and CFC-12 in the study area, whilst a source for CH₃I in the air during spring.