Plant Pb contents in elevation zones of the Changbai Mountain National Nature Reserve, China

Typical plants and soils of four elevation zones, mountain tundra (Zone A), Betula ermanii forest (Zone B), mountain dark coniferous forest (Zone C), and mountain coniferous and broad-leaf forest (Zone D), along the vertical gradient of the northern mountain slope of the Changbai Mountain National Nature Reserve, Jilin Province, China, were sampled to study the relationship between plant and soil Pb, and to compare the Pb levels in typical plant types within the same elevation zone. The Pb contents in the soil and plant samples were measured by using a flame atomic absorption spectrophotometer. The results showed that the average plant Pb contents of the four plant elevation zones were lower than the average worldwide level, except for Zone B. Compared with the average level in China or the average worldwide level, the soil Pb levels of the four plant zones were higher, with Zones D and B having the lowest and highest averages, respectively. Plant Pb levels fluctuated from the upper to the lower zones, in a pattern of low-high-low-high, which was the same as that of the soils in the four zones. Furthermore, plant Pb was closely related to soil Pb. Depending on the plant species and plant parts, large differences were found in the Pb levels of typical plants within each zone. In Zone A, Vaccinium uliginosum and Rhododendron redowskianum had higher Pb levels than the other plants. In Zone C, the Pb levels in the branches of both plant species were higher than those in the leaves, which was contrary to Zone D. In Zone B, the Pb levels in the plant parts varied greatly with plant species.