Phloem from the tree at the eruption site had 9.5 micrograms of the metal per kilogram.
位于喷发点的树上的韧皮部中每千克含有9.5毫克汞。
The two more distant trees had 2.9 and 2.0 respectively.
另外两棵较远的树的韧皮部每千克汞含量分别为2.9及2.0。
The explanation for the discrepancy lay in the trees bark.
产生这种差异的原因就藏在树皮之中。
This had similar mercury levels to the phloem.
树皮的汞含量与韧皮部相近。
What Dr Rodriguez Martin reckons is going on is that trees are using their bark, which theyshed continually, as a waste-disposal system.
罗德里格斯马丁博士认为是这么回事:树木将其不断脱落树皮当做一种废物处理系统。
Mercury is carried there by the phloem and selectively deposited in it, rather than in theplants more permanent parts.
汞通过韧皮部被转运到树皮中,有选择性地在其中沉积,而非在自己不易更新的部位沉积。
The metal is then got rid of when the bark is sloughed off.
然后当树皮脱落时,其中的汞也随之被除去。
That makes it invisible to researchers who come along later. What happens to mercury,moreover, might well happen to other toxic materials.
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