SREL Reprint #2761

Plant Soil Metal Relationships from Micro to Macro Scale

K. Bujtas1, A. S. Knox2, I. Kadar1, and D. C. Adriano3

1Research Institute for Soil Science and Agricultural Chemistry of the Hungarian Academy of Sciences,
H-1022 Budapest, Herman Otto ut 15, Hungary
2Westinghouse Savannah River Company, Building 773-63A, Room 6, Aiken, SC 29808, USA
3University of Georgia, Savannah River Ecology Laboratory, Aiken, SC 29802, USA

Introduction: Experimental data on fate, bioavailability, and effects of metals in the soil plant system are often derived from various culture techniques:
• pot experiments (microcosm),
• larger soil columns or lysimeters (mesocosm),
• or field experiments (macrocosm).
In some studies, solution culture is used instead of soil medium. As the different experimental techniques have various advantages and may yield information on several aspects of the same issue, selection of the most suitable experimental technique is important. However, there are inherent difficulties in interpreting data on plant growth, on bioaccumulation, and phytotoxicity of metals established using different
techniques.
Problems associated with assessment of metal phytoavailability (defined as metals taken up by plant via root uptake) and long-term risks associated with accumulation of high levels of these elements in the soils may be better interpreted if the limitations of the various experimental techniques are known.
This chapter summarizes laboratory and field investigations aimed at studying the advantages and disadvantages of various culture techniques and their applicability as a measure of metal bioavailability (see Chapter 3 for other techniques of bioavailability assessments) and as a tool in the risk assessment of heavily contaminated soils. The experimental studies include
1) greenhouse pot experiments in which various forms of metals originating from flue dust applications to the soil were measured using the sequential extraction technique and the effects of metals on the growth and their uptake into experimental plants were assessed, both in the presence and absence of ameliorants;
2) use of large soil columns, either under field conditions as lysimeters, to assess movement of the metals in the soil profile or in the laboratory for studying plant availability of the metals after addition of metal-enriched sewage sludge to cropped, large, undisturbed soil monoliths; and
3) long-term small-plot field experiments aimed to study the effects of 13 potentially toxic elements on various crops and their potential harm in further steps of the food chain.
All these experiments involve application of several metals, separately or in combination with the growth medium. This chapter will focus on forms, phytoavailability, movement, and plant uptake of zinc (Zn) and chromium (Cr) as examples of an essential, relatively mobile, and a nonessential, more tightly bound element, respectively.

SREL Reprint #2761

Bujtas, K., A. S. Knox, I. Kadar, and D. Adriano. 2003. Plant soil metal relationships from micro to macro scale. p. 175-204 In: R. Naidu, V. Gupta, S. Rogers, R. Kookana, N. Bolan, and D. Adriano (Eds.). Bioavailability, Toxicity and Risk Relationships in Ecosystems. Science Publishers, Inc.

This information was provided by the University of Georgia's Savannah River Ecology Laboratory (srel.uga.edu).