Remediating abilities of different plant species grown in diesel-fuel-contaminated leached chernozem

The phytotoxicity and the possibility of phytoremediation of leached chernozem polluted with diesel fuel (1%) were studied by using eight plant species belonging to the Poaceae and Fabaceae genera. The diesel-fuel concentration in planted unfertilized and ammonium nitrate-supplemented soil was reduced 32-55% and 75-94%, respectively. The effect of phytoremediation was more distinct in unfertilized than in fertilized soil. Using correlation matrix analysis of the relationships between plant resistances to diesel fuel contamination, the number of soil microorganisms (including pollutant degraders) in planted soil, soil enzymatic and respiration activities, and pollutant removal, we found common regularities of phytoremediation of diesel fuel-contaminated leached chernozem for the tested plant species. In unfertilized soil, accumulation of plant biomass was a key point of pollutant removal. This occurred because plants were able to maintain the needed number and activity of hydrocarbon degraders in their root zones. In fertilized soil, the plant-pollutant-microbial interactions tended to intensify the metabolic activity of the soil biota, leading to a dramatic reduction in the hydrocarbon concentration in leached chernozem. At the same time, the relationships between plants and hydrocarbon-degrading microorganisms were not weakened by fertilization. Maize (Zea mays L), sorghum (Sorghum bicolor L Moench), and rye (Secale cereale L) are recommended for use in the phytoremediation of diesel-fuel-contaminated leached chernozem. (C) 2012 Elsevier B.V. All rights reserved.