Characterizing phytoremediation of carcinogenic polycyclic aromatic hydrocarbon naphthalene by Eichhornia crassipes (Mart.) Solms aquatic plant

Abstract

The smallest polycyclic aromatic hydrocarbon, naphthalene can be found in many crude oil-contaminated water bodies. Naphthalene is persistent and considered as very toxic to aquatic life. It is also a cancer-causing agent. Phytoremediation is a cost effective and environment friendly process of removing pollutants from soil or water by living plants. Surfactants can enhance plant uptake of some pollutants. E. crassipes is a free-floating aquatic plant commonly found in fresh water bodies in Sri Lanka. We hypothesized that E. crassipes has the ability to absorb naphthalene from water and surfactant Triton X-100 can enhance naphthalene absorption. Two sets of E. crassipes plants were grown in naphthalene-spiked crude oil-containing water. One set was treated with Triton X-100. Plants grown in fresh water and crude oil-containing water in the presence or absence of Triton X-100 were used as controls. Plant roots were separated, cleaned and freeze dried. Naphthalene was extracted by sonication using 1:1 dichloromethane: acetone mixture and further purified by a silica column. Naphthalene identification and quantification was done using high performance liquid chromatography (HPLC) with a C18 column. According to the results, E. crassipes plant was capable of absorbing naphthalene with an average concentration of 1.14 ± 0.07 mg kg-1. However, surfactant Triton X-100 treatment did not significantly enhance naphthalene absorption. We conclude that E. crassipes plant can be used for phytoremediation of naphthalene. However, surfactant-enhanced phytoremediation was not evident.