为探究颗粒态汞的光还原及可能的二次释放结果,以细颗粒物(PM2.5)为载体,采用Bloom法和冷原子荧光法,在不同光照时长下,收集、测定细颗粒物中汞(PBM2.5)质量和形态分布。结果表明:模拟太阳光照射下PBM2.5发生的化学反应以光还原反应为主,产生的气态汞中90%以上为Hg0,少量为Hg2+;光照促进PBM2.5向Hg0转化;光照时间增加,F5/PBM2.5增加(F5为硫化物态汞),其余形态汞质量主要以指数形式降低;光照促进大气PBM2.5以更稳定的形态存在,正向影响汞沉降。

In order to reflect the photo-reduction and possible secondary release of particle-bound mercury,the distribution variations of PM2.5-bound mercury(PBM2.5)under simulated sunlight were analyzed by using PM2.5 as the carrier,which provided a reference for the study of PBM2.5 speciation transformation and re‐gional mercury pollution assessment. Mercury speciation in PM2.5 was extracted and determined by Bloom and CVAFS respectively.The gaseous mercury produced by PBM2.5 under different light duration was also collected and determined simultaneously.The results showed that under simulated sunlight,photo-reduction was the mainly chemical reaction of PBM2.5.More than 90% of the produced gaseous mercury was Hg0,and a small amount was Hg2+.The transformation of PBM2.5 to Hg0 was mainly affected by illumination,which pro‐moted the transformation.With the increase of illumination time,the volume concentrations of each mercury speciation in PM2.5 decreased exponentially. F5/PBM2.5 increased with the progress of illumination,while other mercury speciation showed the opposite trend,indicating that illumination could promote the existence of particle-bound mercury in a more stable geochemical form and positively affect the deposition of mercury.