南海诸岛土壤的地球化学特征及其生物有效性

南海诸岛主要由三类土壤组成，即富磷岩性均腐土，盐成土和新成土。这些土壤均发育于具有强石灰性的生物碎屑沉积物之上。富磷岩性均腐土的元素含量与母质相比，Ｐ、Ｚｎ、Ｃｕ、Ｂａ、Ｃｄ等元素含量较高，且随成土时间的增加，其含量有增加的趋势，而Ｍｇ、Ｃａ、Ｓｒ、Ｂ、Ｖ、Ｐｂ、Ｍｏ等元素含量较低，随成土时间的增加逐渐降低。新成土和盐成土除Ｐ和Ｎａ元素含量较高外，其余元素均接近母质。南海诸岛独特的生物气候、母质等

PEDOGEOCHEMISTRAND BIOAVAILABILITY OF SOILS IN SOUTH CHINA SEA ISLANDS

There are three soil types in South China Sea Islands, namely, Phosphic Lithomorphic Isohumisols, Holisols and Entisols, which are derived from bio-clastic and strongly calcareous sediments.In comparison with their parent materials, the Phosphic Lithomorphic Isohumisols have higher contents of P, Zn, Cu, Ba, and Cd, which tend to increase gradually with time, and lower contents of Mg, Ca, Sr, B, V, Pb, and Mo, which tend to decrease gradually with time. The above-mentioned constituents in Entisols and Holisols are similar to those in their parent materials except for P and Na, whose contents are higher than those in parent materials. The factors affecting element distribution are mainly special bioclimate and parent materials, which also result in the remarkable influence of soil-forming time on element distribution. Element availabilities of Phosphic Lithmorphic Isohumisols are characterized by enrichment in P, Zn, and Cu, and those of Holisols by enrichment in B. The factors affecting element bioavailabilities in soils are soil acidity, soil organic matter, cation exchange capacity and total element content, among which total element content has the strongest effect on P, Zn, and B availabilities, resulting that distribution of their element availabilites are similar to that of their total element contents.