香港土壤研究Ⅴ.稀土元素的地球化学特征

香港地区缺乏对土壤中稀土元素地球化学的系统研究.本研究采集了该地区46个代表性土壤剖面样品,利用电感耦合等离子体原子发射光谱（ICP-AES）分析了15种稀土元素的总量,并根据土壤剖面的发育情况分层表述.研究结果表明：香港土壤的稀土元素的总量低于全国的平均含量,在剖面分布上由表层往底层逐渐增加.地球化学特征方面,土壤中轻重稀土分馏明显,具有明显的轻稀土相对富集现象.Ce的富集现象在火成岩母质发育的土壤中较为突出,而Eu的亏缺现象在花岗岩母质发育的土壤中尤为显著.成土母岩、土壤矿质元素和基本性质以及地形和植被等都会显著影响香港土壤稀土元素的含量和地球化学特征.

HONG KONG SOIL RESEARCHES Ⅴ. GEOCHEMISTRICAL CHARACTERISTICS OF REAR EARTH ELEMENTS

Geochemical characteristics of rare earth elements(REE) in the soils were deemed to relate to the endemics of a region.In order to determine soil geochemical characteristics of the REE in Hong Kong,46 soil samples typical in Hong Kong were collected and analyzed for contents of rare earth elements with an Inductively Coupled Plasma(ICP) and an Atomic Emission Spectrometer(AES).The results indicate that the average content of REE in Hong Kong soils is relatively lower than in the soils of the Mainland and increases gradually with the depth in soil profile due to downward leaching of the elements.The fractionation between LREE and HREE is apparent in the whole soil profile.The positive anomaly of cerium in the soils developed from pyrogenetic rocks and negative anomaly of europium in the soil from granite are quite distinct.Parent material,major mineral elements in the soils,soil basic characteristics,topography and vegetation are all supposed to make important contribution to the enrichment and fractionation of soil REE.