Evrona nature reserve is located in the Arava valley, at the southernmost part of Israel. Very low precipitation and high summer temperatures characterize this hyper-arid region. Local water regime depends solely on annual floods, which flow from surrounding mountains and accumulate within desert salt flats edged by Vachellia groves (Vachellia tortilis and V.raddiana).
On December 2014, five million liters of crude oil erupted from the Trans Israel pipeline. The oil flowed via the dry waterway into the braided river within Evrona nature reserve. The foremost impact was germination inhibition for Vachellia trees. Researchers found that without mitigation this would remain permanent. As Vachellia are keystone species in the hyper-arid ecosystem, damaging their recruitment will cause the degradation of the entire ecosystem.
Israeli Nature and Parks Authority decided to initiate in situ soil remediation towards reducing oil concentrations, to facilitate Vachellia recruitment. Bioremediation in a hyper-arid environment represent a challenge, as most methods require high soil moister. The selected method aimed to optimize bioremediation success while minimizing disturbance. Initial pilot results showed 77.6% reduction in oil concentration. Unfortunately, the full-scale treatment reduced oil concentration by only 46.4%, which is not sufficient to support Vachellia germination.
The failure of the bioremediation treatment demands additional actions in order to restore germination, which is crucial for retaining ecosystem integrity. As Evrona is the only known incident of crude oil pollution in a hyper-arid nature reserve, finding a successful restoration procedure is crucial for current and future incidences.
