中文摘要：

对上海郊区不同地貌单元的12个土壤—沉积物剖面进行铀、钍含量调查的结果显示,各剖面铀、钍的含量均处于中国土壤背景值范围之内,且表土和下部沉积物之间不存在明显差异,反映尚未遭受到人为污染。铀、钍含量的分布与地貌环境（包括物质来源、物质颗粒组成、有机碳含量以及pH值等）密切相关：贝壳砂堤和火成岩残丘附近剖面的铀、钍最为富集,而新形成的潮滩剖面中铀、钍含量最低。在砂质沉积物占主导且pH值较大的河口沙岛和新滨海平原环境中,铀、钍含量随有机碳含量增加而上升,而在泥质沉积物占主导且pH值偏低的淡水湖沼区,铀、钍含量和有机质含量呈相反关系。

英文摘要：

The present paper investigated the uranium（U）and thorium（Th）content in 12 soil-sediment sections from different geomorphologic units of suburbs of Shanghai. The results show that the content of uranium and thorium is within the background value of soil in China. There is no obvious difference between the soil and the underlying sediments, which reflects that no pollution from human activities occurred. The major factors influencing the distribution of U and Th are closely related with geomorphologic environment including the material source, the particle composition, the organic carbon content, and the pH value. The U and Th reach the highest value in sections close to the chenier ridge and igneous rock hill, while it is the lowest in the newly formed tidal flat. The content of U and Th increases with the increase of organic carbon content in the sections of tidal flat where sandy sediment dominates with higher pH values, but decreases in those of lacustrine plain where muddy sediment dominates with lower pH values.