Fang Guor-Cheng, Wu Yuh-Shen, Chang Shih-Yu, Lin Jum-Bo, Lin Jhih-Guang
Air Toxic and Environmental Analysis Laboratory, Hungkuang University, Sha-Lu, Taichung 433, Taiwan.
Chemosphere. 2007 Mar;67(5):966-74. doi: 10.1016/j.chemosphere.2006.10.068. Epub 2006 Dec 12.
For reasonable and convenient assessments of the characteristics of the dry deposition velocities between Taichung harbor site and Wuchi town site in central Taiwan, the overall dry deposition velocities of several metallic elements were calculated as the particulate diameter (D(p)) distributions of large particles (D(p) > 10 microm), coarse particles (10 microm < D(p) < 2.5 microm), and fine particles (D(p) < 2.5 microm) based on the ambient measurements during March-December of 2004. In this work, the dry deposition fluxes showed the higher correlation with coarse particle concentrations than large particle concentrations; however, the least well correlation was observed between the dry deposition fluxes and the fine particle concentrations. The calculated best-fit overall dry deposition velocities obtained using coarse particle concentrations varied from approximately 0.2 cm s(-1) for Cr to 1.5 cm s(-1) for Pb and 0.2 cm s(-1) for Fe to 2.6 cm s(-1) for Pb at Taichung harbor and Wuchi town site, respectively. In general, the crustal elements had higher deposition velocities than anthropogenic elements. In addition, overall dry deposition velocities for crustal elements were higher in Wuchi town site than in Taichung harbor site. The results identified the dry deposition flux was mainly contributed from large and coarse particles due to their high deposition velocities. The results also indicated that the best approach to estimate overall dry deposition was by depending on the characteristics of particles with diameters larger than 2.5 microm.
为合理便捷地评估台湾中部台中港站点与梧栖镇站点之间干沉降速度的特征，基于2004年3月至12月的环境测量数据，计算了几种金属元素的总干沉降速度，该速度按照大颗粒（粒径>10微米）、粗颗粒（10微米>粒径>2.5微米）和细颗粒（粒径<2.5微米）的粒径（D(p)）分布进行计算。在这项研究中，干沉降通量与粗颗粒浓度的相关性高于与大颗粒浓度的相关性；然而，干沉降通量与细颗粒浓度之间的相关性最差。利用粗颗粒浓度计算得到的最佳拟合总干沉降速度，在台中港站点和梧栖镇站点分别从铬的约0.2厘米/秒到铅的1.5厘米/秒，以及从铁的0.2厘米/秒到铅的2.6厘米/秒不等。总体而言，地壳元素的沉降速度高于人为源元素。此外，梧栖镇站点地壳元素的总干沉降速度高于台中港站点。结果表明，干沉降通量主要来自大颗粒和粗颗粒，因为它们的沉降速度较高。结果还表明，估算总干沉降的最佳方法是依据粒径大于2.5微米颗粒的特征。
