World Aquaculture September 2018

WWW.WA S.ORG • WORLD AQUACULTURE • SEP TEMBER 2018 55 FIGURE 3. Arsenic concentration in aquaponics system water over time. FIGURE 4. Mercury concentration in aquaponics system water over time. FIGURE 5. Change in arsenic concentration in fish and plant tissue between the beginning and the end of the study. FIGURE 6. Change in cadmium concentration in fish and plant tissue between the beginning and the end of the study. FIGURE 7. Change in mercury concentration in fish and plant tissue between the beginning and the end of the study. FIGURE 8. Change in lead concentration in fish and plant tissue between the beginning and the end of the study. Concentrations of As were greater than those of other metals (Cd, Hg and Pb) due to high background levels and increased with time. Mercury levels decreased over time in both the treated and the control systems. Cadmium did not accumulate in fish tissues in treated or control systems but accumulated in lettuce in both control and treatment systems.