Determination of Total Petroleum Hydrocarbon (TPH) and some Cations (Na+, Ca+ and Mg2+) in a Crude Oil Polluted Soil and possible Phytoremediation by Cynodon dactylon L (Bermuda grass)

Abstract

Determination of total petroleum hydrocarbon (TPH) and some cations (Na⁺, Ca²⁺ and Mg²⁺) in a crude oil polluted soil and possible phytoremediation by Cynodon dactylon L. (Bermuda grass) was studied. The soil samples (A, B, C and D), each weighing 5kg were collected. Samples B, C and D were polluted with crude oil at different concentration (B: 30ml/kg, C: 50ml/kg and D: 100ml/kg). Sample A was unpolluted. Total petroleum hydrocarbon and some cations were determined after seven days of pollution and after two months of phytoremediation by Cynodon dactylon L. and the results were compared. The result showed that mean TPH concentration decreased after remediation. Mean TPH concentration in the soil samples before remediation were (477.0mg/kg, 887.4mg/kg, 1156.17mg/kg and 2105.0mg/kg), while values after remediation were (67.7mg/kg, 383.6mg/kg, 357.6mg/kg and 291.0mg/kg)  with  percentage decrease of 85.8, 56.7, 66.8 and 86.2 in A,B,C and D respectively. The result showed that cynodon dactylon L. has the ability to clean-up crude oil polluted soil. Analysis of the plant stems for TPH concentration between the unpolluted sample A. and the most polluted sample D., showed that sample D. has mean TPH concentration of 785.19mg/kg and A. 82.58mg/kg, with percentage increase of 89.4. This significant increase (p>0.05) in TPH concentration after remediation in sample D. than A., clearly indicates that cynodon dactylon L. is responsible for the decrease in TPH concentration after remediation. The result of cation analysis after pollution showed that Mg²⁺ and Ca²⁺ had no significant difference in the soil samples irrespective of the level of pollution (p<0.05). Na⁺ concentration increases with increase in the level of pollution.

Key words: Total petroleum hydrocarbon, Phytoremediation