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Fig. 4. Concentration and time effects on "bioavailable" copper concentration ([Cu]bio) in water extracts from soil systems. (A) [Cu]bio measured with the Cu-reporter strain DF57-Cu15 in water extracts from Cu-amended soils 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. The data presented are from duplicate soil systems and each point represents a single soil system. (B) [Cu]bio in water extracts in percentage of added Cu, as 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. (C) [Cu]bio as fraction of total copper concentration ([Cu]tot) in water extracts and a dose of 100 (squares), 200 (crosses), 400 (triangles), and 800 (diamonds) µmol Cu kg–1 soil, as function of the incubation time.
