PHYTOREMEDIATION OF HEPTACHLOR AND HEPTACHLOR EPOXIDE IN SOIL BY CUCURBITACEAE

Abstract

Plants in the family of Cucurbitaceae family are known to up take organochlorines. This study was designed to screen seven cultivars of the Lagenaria siceraria species of the Cucurbitaceae family to determine their capacity to remediate heptachlor- and heptachlor epoxide-contaminated soil. The seven Lagenaria cultivars were grown in contaminated and uncontaminated Molokai soil for 13 weeks. The results showed that all the plants tolerated heptachlor and heptachlor epoxide at levels of 0.169 and 0.376 μg/g, respectively, in the soil and were able to bear a limited number of immature fruits during the short study period. All seven Lagenaria cultivars showed some ability to up take heptachlor epoxide into their vines with bioaccumulation factors varying from 1.0 to 5.2. The two contaminants were not detected in the fruits and heptachlor itself was not detected in the vines. The mean concentrations of heptachlor in the soil of all the pots including the no-plant control were not significantly different from that in the initial soil, which might be due to the gradual release of the soil soil-bound heptachlor residues. In the soil, all pots showed a significant decrease for heptachlor epoxide as compared to the initial level, but there was no significant difference between the no-plant control pots and the planted pots of six of the seven cultivars. The local Hyotan cultivar showed the largest decrease, from 0.376 down to 0.050 μg/g dry soil, and was the only cultivar showing a significant difference in the soil heptachlor epoxide concentration with the no-plant control.