海南岛西南干旱区土壤中稀土元素含量及其空间分布特征

Spatial distribution of REE elements contents in arid area of southwest Hainan Island

对海南岛西南干旱区发育典型的5个土壤剖面的稀土元素组成特征及其垂向变化规律进行研究,结果表明:成土母质决定着土壤中稀土元素的最初含量,同一土壤剖面上下层之间的稀土元素具有一定的继承性。由花岗岩风化而成的土壤的稀土元素含量大于砂页岩风化而成的土壤,土壤表层强烈的淋溶作用又导致由土壤剖面深部至浅部∑REE逐步减少。成土母质决定了土壤中呈现的轻稀土富集的特点。区内特殊的自然地理条件、Eu自身的地球化学特性及成土母质决定了Eu亏损的特点。土壤剖面表层氧化和水解作用导致Ce在土壤表层中的富集,并导致由剖面深部至浅部,Ce呈现出由负异常向正异常演化的趋势。

Various soil samples were collected from five soil profiles in the southwest Hainan Island, and the REE composition features of these samples and their spatial changes in these soil profiles were analyzed. The an- alytical results show that the total REE contents in soils are correlative with bothmaterial horizon. Moreover, the total REE contents of soil which were developed from granite are higher than those developed from sand - shale rocks, and the total REE contents decreased from horizon A to horizon C in each soil profile. With the intensive development of soil, LREE gains and HREE lose. The results also indicate that the negative Eu anomaly of soil is due to both the special geographical conditions and geochemical characteristics and bothmaterial horizon, but the tendency of negative Ce anomaly turns out to be positive Ce anomaly from horizon C to horizon A of soil profiles is resulted from the migrat ion of REE due to oxidation and hydrolysis at the top of the soil profiles.