Revista internacional de contaminación ambiental
versão impressa ISSN 0188-4999
VAZQUEZ-LUNA, Dinora et al. Crotalaria incana L. and Leucaena leucocephala Lam. (Leguminosae) as indicators of toxicity by petroleum hydrocarbons in soil. Rev. Int. Contam. Ambient [online]. 2010, vol.26, n.3, pp. 183-191. ISSN 0188-4999.
This study assesses the toxic effects produced by a Gleysol molic soil contaminated with crude oil on seedlings of two species of legumes. A phytotoxic impact index (IIF) was generated, which includes five parameters measured by relative rates of impact (IRIF(x)) for variables; emergency, height, root length, aboveground biomass and root biomass. Bioassays were conducted under a completely randomized design with three replications under semi-controlled conditions, to assess the sensitivity of Leucaena leucocephala and Crotalaria incana at different concentrations of HTP (total petroleum hydrocarbons). Effects were highly significant (P ≤ 0.01) with increasing concentrations of HTP in substrate. The emergence of L. leucocephala was 29 % lower with 80 000 mgkg-1 HTP, while C. incana decreased 30 % with 32 000 mgkg-1 HTP respect to control. Both species showed a five-day delay in the emergence of seedlings when exposed to high levels of HTP. A significant decrease in the accumulation of dry matter (DM) at concentrations above 20 000 mgkg-1 HTP was observed in both species. The respective IIF declined of 50 % with 80 000 and 25 000 mgkg-1 TPH, but L. leucocephala had no significant effect with 10 000 mgkg-1 TPH. Finally, the EC50 in L. leucocephala, is presented with 80 000 mgkg-1 TPH whereas in C. incana this parameter is noted from 25 000 mgkg-1 TPH.
Palavras-chave : EC50; crude oil; phytotoxicity index; soil pollution; total petroleum hydrocarbons.