Effects of Water Soluble Fractions of Crude Oil, Diesel Fuel and Gasoline on Salvinia nymphellula (Desv)

Abstract

The study investigated the effect of water soluble fractions (WSFs) of crude oil, diesel fuel and gasoline on Salvinia nymphellula (Desv).  The parameters measured include number of leaves, biomass production, relative growth rate (RGR) and doubling time (DT). The WSF concentrations used were 25, 50 and 100% for crude oil and diesel fuel, 5, 10 and 20% for gasoline.  The result showed that leaf production, biomass production and relative growth rate (RGR) were significantly reduced (P<0.01) in S. nymphellula when exposed to all concentrations of the WSFs for four weeks.  Doubling time (DT) was also increased.  The effects were concentration and medium dependent.  WSF of gasoline had the most toxic effect.  The macrophyte leaves were chlorotic, withered and disintegrated after four days in concentrations above 25% WSF of gasoline.  There was no significant difference (P<0.05) between the effects of WSF of crude oil and WSF of diesel fuel on leaf production even though WSF of diesel had a more toxic effect on biomass production and relative growth rate in S. nymphellula than WSF of crude oil. These findings suggest that WSFs of petroleum hydrocarbons are toxic to aquatic macrophytes and early response to oil spillages is therefore recommended.

Keywords: Salvinia nymphellula, water soluble fraction, crude oil, diesel, gasoline.