Cadmium Distribution in a Timberline Forest in the Hengduan Mountains in the Eastern Tibetan Plateau

Abstract

In order to study the regional distribution, characterization, and possible source of Cadmium in the eastern Tibetan Plateau, samples of leaves, xylem, twigs, bark, and roots of timberline forest trees (fir or spruce) and soils at depths from 0 to 40 cm were collected in eight sites in Hengduan Mountains. According to Cd contents, organs and tissues were divided into three groups: the highest-level organ (roots: 0.237 mg · kg⁻¹), the high-level organ/tissue (bark: 0.183 mg · kg⁻¹ and twigs: 0.159 mg · kg⁻¹), and the low-level organ/tissue (xylem: 0.054 mg · kg⁻¹and leaves: 0.048 mg · kg⁻¹). Cd contents in Transect A were a little higher than Transect B. Sites near pollutant sources and high-levels are more sensitive to Cd pollution and accumulated more Cd, while Cd contents in sites far away from pollutant sources and low-level organ/tissue were relatively low. It is suggested that the eastern Tibetan Plateau has already been polluted by the influence of general circulation to some extent. Nevertheless, low Cd contents in some sites prove that high mountains may barricade Cd pollutants from monsoon.

Keywords:

• Cadmium
• Eastern tibetan plateau
• Hengduan mountains
• Timberline

Acknowledgments

The present work received financial support from the Knowledge Innovation Project of the Chinese Academy of Science (grants KZCX2-YW-BR-21 and KZCX2-EW-309) and the National Natural Science Foundation of China (grant 40871042).