我国海南岛属热带季雨林-砖红壤地带。主要地带性土壤为砖红壤,同时还有赤红壤、燥红壤、滨海盐土和水稻土等。在900公尺以上的山地,尚有山地黄壤的分布。 高温多雨的气候条件和强烈的生物地球化学作用,使该地区的自然地理过程终年进行,而且强度很大,形成深厚的红色风化壳。土壤形成过程也相当强烈。

The Hainan Island is belonged to the tropical seasonal rain forest laterite zone. Thelatosol dominates this zone, but as an exception, there are also lateritic red soil, paddysoil, coastal solonchak and dry red soil. The mountain yellow soil is distributed at 900 mhigh mountainous region. The neutron activation method was used to determine thechemical elements of the soils in Hainan Island. 28 elements and A.B.C. three naturalgenetic horizons were analysed for each type of soil and the result illustrated as follows:1. The abundance of Cu, Zn, Ni, Co, As, Sr in tropical soils are very low whencompared with the soils of Northern China. The abundance of Cu is 14.3, As 7.30, Ni39.2, Co 9.03 ppm respectively. The abundance of Zr, Th and Fe are high than that ofNorthern China, they are 706.9. 40.6, and 4X104 ppm. This is due to the intense wea-thering and leaching of tropical regions.2. The abundance of rare elements and rare earth elements in lateritic red soilderived from granite are higher than the latosol which derived from basalt, for example,the abundance of Zr and La in latosol derived from granite are 1996.7 and 118.1 ppm.The parent material is an important factor.3. The rate of Zr/Hf from dry red soil, yellow soil, lateritic red soil to latosol arerespectively 31.8, 33.8, 42.3, 48.5. This illustrates the relatively light to heavy weatheringof the soil.4. The abundance of rare earth elements in soil are richer than that in chondrite.The abundance of Bu in the yellow soil, podzolic yellow soil and paddy soil and theabundance of Ce in the limestone red soil derived from limestone show a negative ano-maly.5. In eight samples, the total amount of abundance of eight rare earth elementsare 0.021%, in which Ce takes 41.3%.