海南省若干树木中的微量元素

Trace Elements in Some Trees of Hainan Province

海南地处热带地区，土壤富铝化作用强烈，元素生物小循环迅速，但树木中Ｃｄ，Ｎｉ，Ｃｕ，Ｚｎ，Ｐｂ，Ｈｇ的质量分数在正常范围值，其ｗＢ因树木种类不同而有明显差异，荔枝的ｗＢ一般较高，Ｃｄ，Ｎｉ，Ｐｂ居各树木之首；而南亚松ｗＢ通常较低，Ｃｄ，Ｎｉ，Ｃｕ，Ｚｎ，Ｐｂ为各树木最低．树木对必需元素Ｚｎ，Ｃｕ的吸收量明显高于非必需元素Ｐｂ，Ｃｄ，Ｎｉ，Ｈｇ，大多数树木的化学组成（ｗＢ）是：Ｚｎ＞Ｃｕ＞Ｐｂ＞Ｃｄ＞Ｎｉ＞Ｈｇ．Ｈｇ，Ｃｄ，Ｎｉ的质量分数大多叶高于枝，而ｗ（Ｃｕ）大多数是枝高于叶．

The rate of biological cycles of trace elements in the trees of HaiNan Province are analyzed. The average mass fractions of the trace elements in the trees are as follows: Cu 6 87×10 -6 , Zn 21 61×10 -6 ,Ni 0 68×10 -6 , Cd 0 93 ×10 -6 ,Pb 1 83 ×10 -6 , Hg 0 050×10 -6 . Each of them is at normal level. The mass fractions of essential trace elements such as Zn and Cu are higher than those of Pb, Cd, Ni and Hg.The order of the mass fractions in most of the trees is Zn>Cu>Pb>Cd>Ni>Hg.The values of Hg, Cd and Ni in leaves are higher than those in branches, while the value of Cu is usually reverse.The mass fractions of trace elements in trees vary with species of trees and ecological environment.