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Abstract:

The capacity of organo-zeolitic material was evaluated as an amendment for the treatment of soils polluted with heavy metals. Three soil experimental variants were used: experimental variant (sample I), untreated, polluted soil with Pb (4330ppm), Zn (377ppm), Cd (27.29ppm) and Cu (50.2ppm), experimental variant (sample II), polluted soil treated with organo-zeolitic material and experimental soil control variant (sample III). Sinapis alba L. was used as the test plant. The application of the organo-zeolitic material increased significant the production of biomass (795g) compared to the control soil (108.63g) and untreated soil (27g). Growth of plants on the untreated polluted soil was strongly inhibited by high metal content, low pH, lack of nutrients. The best evolution happened for the plants of the experimental variant (II sample). The accumulation of heavy metals is significant in all vegetative organs of the plant from experimental variant II. However, the plants did not show toxic effects of aerial vegetative organs. In the root of plants from experimental variant II, a very high content of Pb (1.107.1 mg/kg) and Zn (505.3 mg/kg) followed by Cu (49.7) mg/kg and Cd (9.33mg/kg) was observed. In the shoot (25.7mg/kg) and in the leaves (17.8mg/kg) the content of Pb decreases below the toxicity limit. The Zn concentration in the shoot and leaves is high (95.2 and 116.1mg/kg). The content of Cd in the shoots and leaves of plants grown on polluted soil treated with organo-zeolite exceeds the maximum permissible content of 1mg/kg and falls within the range specific to the toxicity range. Applying organo-zeolite treatment to heavy metal polluted soil has favored the accumulation of high amounts of metals in the roots but a poor translocation in shoots and leaves. Zn and Cu were accumulated the most and Pb the least. The value of the transfer factor in mustard leaves was higher in plants from the control soil than in mustard plants from the experimental variant treated with organo-zeolitic material. Spectrophotometric analysis of the mustard leaves extract indicated a significantly higher content of photosynthetic pigment (chlorophyll a, b and carotenoids) for the plants grown on the soil treated with organo- zeolite compared to the plants grown on the control soil.