This study investigated the effects of inorganic fertilizer (N15P15K15) amendments on crude oil uptake by water hyacinth. Experimental units (water hyacinth grown in fresh water) were spiked with 0, 20, 40 and 60 mg/L crude oil. After 24 h, they were randomly assigned fertilizer (N15P15K15) at three different concentrations; 0, 6 and 10 mg/L. Crude oil degradation and absorption were determined by measuring total petroleum hydrocarbon (TPH) in the water column and water hyacinth, respectively. The measurements were taken monthly for six months (February–August 2010). The results showed that TPH concentration in the water column in the treatment amended at 6 mg/L (0.30 ± 0.01 mg/L) was significantly lower (p < .05) than the treatment amended at 10 mg/L (0.76 ± 0.15 mg/L) but was similar to the control (0.33 ± 0.03 mg/L). The water hyacinth in the control (phytoremediation) absorbed significantly higher (p < .05) TPH than the fertilizer-amended treatments. The first-order kinetic model gave a better description of the degradation of petroleum hydrocarbons. The study showed that phytoremediation of crude oil by water hyacinth and biostimulation with fertilizer (N15P15K15) is possible.
The authors are grateful to Dr Excellence Akeredolu of Department of Zoology, Faculty of Science, University of Lagos, Nigeria, for his useful comments on the manuscript.
No potential conflict of interest was reported by the authors.
This work was funded in part by a grant from Pure Earth, formerly the Blacksmith Institute.