Long-Term Biomonitoring of Soil Contamination Using Poplar Trees: Accumulation of Trace Elements in Leaves and Fruits

Abstract

Phytostabilization aims to immobilize soil contaminants using higher plants. The accumulation of trace elements in Populus alba leaves was monitored for 12 years after a mine spill. Concentrations of As and Pb significantly decreased, while concentrations of Cd and Zn did not significantly over time. Soil concentrations extracted by CaCl₂ were measured by ICP-OES and results of As and Pb were below the detection limit. Long-term biomonitoring of soil contamination using poplar leaves was proven to be better suited for the study of trace elements. Plants suitable for phytostabilization must also be able to survive and reproduce in contaminated soils. Concentrations of trace elements were also measured in P. alba fruiting catkins to determine the effect on its reproduction potential. Cadmium and Zn were found to accumulate in fruiting catkins, with the transfer coefficient for Cd significantly greater than Zn. It is possible for trace elements to translocate to seed, which presents a concern for seed germination, establishment and colonization. We conclude that white poplar is a suitable tree for long-term monitoring of soil contaminated with Cd and Zn, and for phytostabilization in riparian habitats, although some caution should be taken with the possible effects on the food web.

Supplemental materials are available for this article. Go to the publisher's online edition of International Journal of Phytoremediation to view the supplemental file.

KEY WORDS:

• Salicaceae
• trace elements
• bioindicators
• Populus alba
• Guadiamar
• phytostabilization

ACKNOWLEDGMENTS

This study was supported by AGL2008-00985, CGL2008-04503-C03-01 and CGL2011-30285-C02 projects, funded by the CICYT of the Spanish Ministerio de Ciencia e Innovación, and European FEDER funds. We thank two anonymous reviewers for their comments on an early version of the manuscript.