Survivorship of Pinus Taeda Exposed to Benzene-Based Compounds: Preliminary Study to Support Phytoremediation Greenhouse Experiment.

The soil and groundwater of a former pesticide plant, located above the floodplain in southern Brazil, has been contaminated by benzene-based compounds. The current groundwater concentrations (CC) of the three main compounds at the site are: 100 mg L^-1 of Chlorobenzene (CB), 50 mg L^-1 of Benzene (BZ), and 0.3 mg L^-1 of 1.2-Dichlorobenzene (DB). Given the solubility of these compounds at 20^oC in water: 500 mg L^-1 for CB, 1,800 mg L^-1 for BZ, and 8,700 mg L^-1 for DB. Thus, for that CC the 3 compounds are below the solubility. We are evaluating the potential of Eucalyptus urugrandis and Pinus taeda to facilitate degradation of these compounds (phytoremediation) and reduce the flow of groundwater to a nearby river (phytopumping). To verify if the plants could survive exposure to these contaminants, we exposed seedlings of Pinus taeda potted in small cones of PVC (20 cm high by 4.5 cm of dia.) containing an unfertilized commercial soil mix (Fafard 3M) and irrigated them daily to field capacity using 5 contaminant treatments (n=4): 0 (control), 0.1xCC, 1xCC, 10xCC, and 50xCC. After 25 days, no plant mortality was observed, even in the highest concentration treatment (50xCC), in which both Chlorobenzene and Benzene exceeded their aqueous solubility. In fact, plant growth was observed in all treatments (no significant difference between the treatments; p=0.92) at rate of 2.0 ± 0.8 cm per month. With these results we are proceeding to evaluate compound degradation (phytoremediation) during a six-month exposure of Eucalyptus urugrandis and Pinus taeda to the contaminants, and the results will be also be presented.