Laboratory and field measurements of dry deposition of sulfur dioxide onto Chinese loess surfaces.

Laboratory and field measurements were conducted to examine dry deposition of SO 2 onto Chinese loess surfaces using native soil sampled in the loess plateau, China. The field tests were employed in Beijing and Lanzhou, China, by directly measuring the dry deposition of SO 2 on soil, which uses soil put on a collector as an SO 2 passive sampling medium. In the laboratory, a high rate of uptake to SO 2 deposition for Chinese soil surfaces due to the highly alkalinity was found. The uptake of SO 2 deposition was dependent on the pH soil and relative humidity. Furthermore, we evaluated some factors that affect the measurement precision: response of SO 2 uptake, repeatability, recovery factor, and variability associated with the weight and the surface coverage on the collectors. As a result, it was shown that the measurement precision was primarily related to the ratio of the SO 2 deposition amount relative to the sulfur content of the original soil. This result was consistent with the field observations. The laboratory and field results indicated an excellent agreement on the SO 2 uptake inherent in the results from the soil surfaces in different regions.