Fig. 3. Concentration and time effects on total copper concentration ([Cu]_tot) in water extracts from soil systems. (A) [Cu]_tot of soil systems spiked with different levels of Cu after incubation for 1 h (circles), 19 h (squares), 8 d (triangles), 32 d (crosses), and 220 d (diamonds). Fitted linear regression lines for each incubation period are shown. (B) Recovery of amended Cu in water extracts as a function of the incubation time and dose of 100 (squares), 200 (crosses), 400 (triangles), and 800 (diamonds) µmol Cu kg^–1 soil. Fitted logarithmic regression lines for each Cu amendment are shown. The data presented are from duplicate soil systems and each point represents a single soil system. One data point (200 µmol Cu kg^–1 soil, 8 d) and two data points (800 µmol kg^–1 soil, 220 d) are missing due to loss of samples.