Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: June 1, 2001
Publication Date: July 27, 2001
Remediation of large areas of metal contaminated land requires a simple and inexpensive technology. Making soils calcareous remediates Ni phytotoxicity because it reduces the solubility of soil Ni. This experiment tested the effectiveness of liming in ameliorating Ni phytotoxicity to various agricultural crops differing in Ni-tolerance, and also the effect on phytoextraction of Ni by Ni-hyperaccumulator Alyssum species which allow recovery and recycling of soil Ni. Testing the effect of soil pH on Ni accumulation by Alyssum species was needed to determine whether rasing soil pH for in situ amelioration of Ni phytotoxicity would interfere with Ni phytoextraction. Greenhouse pot studies were conducted with Ni-contaminated soils from Port Colborne, Ontario, adjusted to varied pH levels from acidic (pH 5.2) to alkaline (pH 7.8). After pH adjustment and fertilization, plants were grown for up to 60 days. Three crop plants, oat, wheat and redbeet were killed at low pH, but had greatly reduced Ni concentration (below phytotoxic thresholds), and no apparent phytotoxicity when the soil was made calcareous. Wheat was much less sensitive to Ni than oat or redbeet. The phytotoxicity and solubility of soil Ni were similarly reduced by raising pH. However, the Alyssum species had increased shoot Ni concentration as pH increased. The remarkable increased uptake while soluble Ni was decreased with increasing pH will be very important in commercialization of Ni phytoextraction, and allows liming to both correct potential toxicity to crop and wild plants and improve the effectiveness of phytoextraction by hyperaccumulators.