0 one of several types of simple chemical substance that are necessary for healthy growth and development, and exist in animals and plants in very small amounts -- 微量元素
The changes in major and trace element composition of the samples are very complex and seem not to change systematically.
Representative basalt samples were selected for major and trace element analysis, excluding those with obvious alteration.
We therefore suggest that the analysed part of the gabbroic pegmatite represents a 'cumulate' from which an incompatible trace element-enriched melt has escaped.
It exhibits a wide trace element compositional range.
Appendices provide clearly tabulated data on major and trace element analyses for all the samples discussed in these chapters.
Identification of petrogenetic processes using covariance plots of trace element data.
Copper is an essential trace element but most diets contain a little more copper than is needed.
The trace element variation within groups is very small.
