Effect of hydrocarbons on the germination of Larrea divaricata and Pappostipa speciosa in the Monte Desert of Argentina

Abstract

In Monte Desert, one of the most arid regions in Argentina, there is an important hydrocarbon basin and the main shale oil reservoir in South America. An intense oil activity takes place there through rock fractures, where failures and spills can occur. Loss of hydrocarbons due to high pressure conditions, produce emissions into the air in the form of sprays that can be deposited in large areas on the ground (blow outs). In samples of uncontaminated soil and soils affected by a blow out event we evaluated seed germination under laboratory conditions of keystone species: Larrea divaricata Cav. and Pappostipa speciosa (Trin. & Rupr.) Romasch. In uncontaminated controls, germination probabilities varied between 0.55 and 0.66 for L. divaricata and between 0.76 and 0.86 for P. speciosa. In contrast, in contaminated soils, germination probability was significantly lower for both species: 0.01–0.02 for L. divaricata and 0.2–0.25 for P. speciosa. We conclude that the presence of hydrocarbons significantly decreases germination of the studied species. Therefore, natural regeneration in arid regions can be seriously affected by hydrocarbon spills.