THE EFFECTS OF LONG-TERM AGING ON THE DISTRIBUTION AND BEHAVIOR OF HEAVY METALS IN THE SOIL: SOLUBILITY, MOBILITY, BIOAVAILABILITY, AND TOXICITY
Sewage sludge is frequently applied as an agricultural fertilizer. However, this sludge often contains toxic metals, which contaminate the soil and create a risk for agriculture, as well as for humans, animals and plants in the surrounding environment. This dissertation analyzes the effects of long-term aging on the distribution and behavior of heavy metals (Cd, Cu, Pb, Zn, and Ni) in the soil, including solubility, mobility, bioavailability, and thus, toxicity. In 1978, a heavy application of metal-contaminated sewage sludge occurred at the Cornell Orchards in Ithaca, NY. This study examines the field site 40 years after this single application and compares it to a nearby site where sludge was not applied. The physical-chemical characteristics of the soil are measured by inductively coupled plasma optical emission spectroscopy (ICP-OES), and toxic metal availability is assessed using a sequential extraction procedure. The leaching of metals from the soil is estimated based on an experiment designed to simulate natural rainfall-driven leaching conditions. The bioavailability and plant uptake of the metals are determined by growing soybeans in sludge-contaminated and control soil samples. This dissertation also presents several new analytical methods that were developed in the course of the study, including the measurement of silver concentration using ICP-OES and the sequential extraction of metals from specific phases in the soil. This dissertation adds to our understanding of toxic metal solubility in the soil and proposes management methods to limit deleterious effects on soil productivity and environmental quality.
Chemisry; Soil Chemistry
McBride, Murray Brian
Wayne, Randy O.; Vatamaniuk, Olena K.; Rutzke, Michael A.
Soil and Crop Sciences
Ph. D., Soil and Crop Sciences
Doctor of Philosophy
dissertation or thesis