Effect of climatic variables on chromated copper arsenate (CCA) leaching during above-ground exposure

Until recently, most research on the leaching of preservatives from treated wood was conducted in the laboratory. Although these studies have contributed to the understanding of leaching, the data generated under controlled conditions often do not apply to leaching during natural exposure and weathering. In addition, little is known about the effects of climatic variables and long-term emission rates. This paper examines leaching of chromated copper arsenate (CCA) from lumber exposed above ground to 685 mm of precipitation during 351 days of natural weathering. Stepwise multiple regression analysis revealed relationships between leaching and a number of treatment and climatic variables, including: species of wood, initial preservative loading, amount of precipitation, average air temperature, average light intensity, pH and duration of rain event. Regression models explained approximately 30% of the variation in chromium and arsenic leaching and 44% of the variation in copper leaching.