Enhancing the Phytoremediation of Hydrocarbon-Contaminated Soils in the Sudd Wetlands, South Sudan, Using Organic Manure

Abstract

Phytoremediation of hydrocarbon-contaminated soils is a challenging process. In an effort to enhance phytoremediation, soil was artificially contaminated with known concentration of light crude oil containing Total petroleum hydrocarbon (TPH) at a concentration of 75 gkg −1 soil. The contaminated soil was subjected to phytoremediation trial using four plant species ( Oryza longistaminata, Sorghum arundinaceum, Tithonia diversifolia , and Hyparrhenia rufa ) plus no plant used as control for natural attenuation. These phytoremediators were amended with concentrations (0, 5 and 10 gkg −1 soil) of organic manure (cow dung). Results at 120 days after planting, showed that application of manure at concentrations of 5 and 10 gkg −1 soil combined with an efficient phytoremediator can significantly enhance reduction of TPH compared to natural attenuation or use of either manure or a phytoremediator alone (<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M1"><mml:mrow><mml:mi>p</mml:mi><mml:mo>&lt;</mml:mo><mml:mn>0.05</mml:mn></mml:mrow></mml:math>). The study also showed that a treatment combination of manure 5 gkg −1 soil, with a phytoremediator gives a similar mean percentage reduction of TPH as manure 10 gkg −1 soil (<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M2"><mml:mrow><mml:mi>p</mml:mi><mml:mo>&gt;</mml:mo><mml:mn>0.05</mml:mn></mml:mrow></mml:math>). Therefore, the study concludes that use of phytoremediators and manure 5 gkg −1 soil could promote the restoration of TPH contaminated-soils in the Sudd region of South Sudan.