Leaching of copper, chromium and arsenic from utility poles treated with chromated copper arsenate (CCA) in Newfoundland and Labrador

• Main Author: Arisi, Joseph Abraham
• Format: Thesis
• Language: English
• Published: Memorial University of Newfoundland 2006
• Subjects: Newfoundland; Canada
• Online Access: https://research.library.mun.ca/10096/; https://research.library.mun.ca/10096/1/Arisi_JosephAbraham.pdf

Chromated Copper Arsenate (CCA) is a timber preservative used to treat utility poles in Canada. The aim of this study was to determine (i) the amount of leaching of Cu, Cr and As from utility poles and diffusion of Cu, Cr and As into soil under natural conditions (ii) the variation in concentration of leaching of Cu, Cr and As with pole age, (iii) the temperature effects on leaching of Cu, Cr and As (iv) the effect of amount of rainfall on the rate of leaching of Cu, Cr and As (v) the other climatic effects on leaching of Cu, Cr and As and (v) soil properties like cation exchange capacity (CEC), pH and total organic carbon (TOC) of the contaminated soil samples. A total of 114 surface soil samples were collected around 28 Douglas fir utility poles at distances of 0, 0.30, and 0.60 m and three background samples were collected at a distance of 7.0 m from the poles. Also a freshly treated, 1.50 m long wooden log section was suspended outside in a large cylinder to collect runoff. The Cu:As:Cr (molar) ratios of the average metal contents in the soil samples collected at a distance of 0 m, and in the runoff from the pole segment, were 100:46:56 and 100:44:57, respectively. At 0.60 m distance the metal concentration had reached background levels. The results suggested that As was more mobile than the Cr and that the Cu, Cr and As were being continuously leached from the poles over time. 13-yr poles leached the highest amount of concentration of Cu, Cr and As followed by 1-yr old poles and then 2-yr old poles. 1-yr old poles leached more As than Cr. 13-yr-old poles leached the highest amount of Cr. North or South directions from the poles generally had the highest amount of leaching. The leaching was more dependent on amount of rainfall than temperature. A correlation between the soil CEC and TOC was observed.