Copper solubility and speciation of in situ contaminated soils: Effects of copper level, pH and organic matter

This study attempts to identify the soil properties controlling the fractionation of copper into various soil pools and determine the influence of pH and metal loading on soil-solution free copper activity (pCu(2+)). The pCu(2+) was determined in 0.01 M CaCl2 soil extracts using a copper ion selective electrode. We analyzed a wide variety of soils: urban, agricultural and forest soils from the Province of Quebec, New York State and Denmark. The pCu(2+) ranged from 12.21 to 6.18. The relationships among pCu(2+), total soil copper, total dissolved copper and soil pH are studied for their variability within and between sites as well as for the whole data set. Regression equations are presented for predicting soluble copper as a function of total soil copper and also for predicting pCu(2+) as a function of total soil copper and soil pH.