39    HEAVY METAL UPTAKE DURING THE GROWTH
OF DURUM WHEAT FROM APPLICATION OF SEWAGE
SLUDGE AND COMMERCIAL FERTILIZER
Heather L. Frost, Graduate Research Assistant
Lloyd H. Ketchum, Jr., Associate Professor
Jinesh C. Jain, Assistant Professional Specialist
Clive R. Neal, Associate Professor
Department of Civil Engineering and Geological Sciences
University of Notre Dame, Notre Dame, Indiana 46556
ABSTRACT
Repetitive application of commercial fertilizer continually introduces toxic heavy metals to the
soil. Such metallic toxins are subsequently taken up by food crops. Sewage sludge, usually disposed of in landfills, contains high nutrient and organic contents and is now being recycled and
applied to agricultural land worldwide in increasing amounts. Metals in sewage sludge are generally organically bound and generally less available for plant uptake than the more mobile metal
salt impurities found in commercial fertilizers. However, it is predicted that a slow mineralization of organic matter in sludge releases metals into more soluble forms over time.1 This research
is a preliminary project which gives indication as to metal accumulation in durum wheat roots
and the difference between metal salt accumulation and the risk of a 20-year-old sludge with organically bound metals. Future studies will determine metal accumulation in different regions of
the durum wheat plant. This information is especially important to phytoremediation issues, giving an indication as to which part of the wheat plant provides maximum uptake of a specific
metal and as such, could be used to remove metal from the soils.
Initially, this project focused on screening of U.S. durum wheat lines, common commercial
fertilizers, and sludge for 15 potentially threatening elements using inductively coupled plasma
mass spectrometry (ICP-MS). Metal uptake studies in a high Cd durum wheat were carried out in
greenhouse grown plants using applications of a 20-year-old sewage sludge from the Goshen, Indiana Waste Water Treatment Plant and a commonly used 13-13-13 commercial phosphate fertilizer. Results of this first-phase of research include: (1) an assessment of the effect of sludge application on Cd uptake in durum wheat roots; (2) a comparison of accumulation of Cd uptake in
durum wheat using commercial fertilizers; (3) an evaluation of differing metal uptake following
use of single or multiple application strategy; and (4) an identification of the metals in addition
to Cd that may serve as a threat to the export of U.S. durum wheat.
INTRODUCTION
Sewage sludge is the solid portion which remains after wastewater treatment and which is frequently disposed of in landfills. Because of its high content of nutrients and organic matter,
sludge has been applied worldwide in increasing amounts to agricultural lands for the past several decades. The total cost of land applying sludge is estimated to be 25% of the cost of alternative disposal methods such as elutriation, filtration, or incineration.2 Effective industrial pretreatment and monitoring by wastewater treatment facilities can ensure the sludge produced is low in
toxic contaminants, both organic and inorganic, and high in nutrients and humus, thus rendering
sewage sludge as an effective and cheap alternative to commercial fertilizers. However, the numerous heavy metal contaminants in sewage sludge and phosphate fertilizers are either useless in
52nd Purdue Industrial Waste Conference Proceedings. 1997, Ann Arbor Press, Chelsea, Michigan 48118. Printed in
U.S.A.
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