The Effect of Oilfield Brine on Soil Properties and Plant Growth
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Date
2021-05-19
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Abstract
Uganda is an emerging petroleum-producing country, and protecting vulnerable ecosystems in the impacted areas is paramount. In this study, simulated Ugandan petroleum brine was applied to soils to duplicate the conditions of brine spills. The brine to be used in Ugandan oil fields will be dominated by Na+, K+, Clˉ, and HCO3ˉ with lower concentrations of potentially toxic metals including Sr and Ba. When brine was applied to the soil at rates high enough to reach electrolytic conductivities of EC 3 and EC 9 dS m-1, respectively, soil properties and plant growth were heavily impacted. Redistribution of exchangeable cations and soil dispersion were observed for both rates of brine application. SAR was elevated to 12 and 18, and ESR was increased to 0.22 and 0.46 for EC3 and for EC9 treatments, respectively. The impacts on plant biomass were dependent upon the target species: cowpea (Vigna unguiculata L.) biomass decreased significantly, Bermudagrass (Cynodon dactylon) was slightly impacted, and sorghum sudangrass (Sorghum × drummondii hybrid) increased in biomass with increasing brine additions. Brine enhanced Ca2+ and Mg2+ content in root but not in shoot, while K+ and Na+ increased in shoot and root for all the species. Ba and Sr application did not have significant impact on soil properties or plant growth. From this study, we concluded that a single spill of brine solutions can result in significant damage to soils and vulnerable plants. Careful management will be required to avoid environmental problems associated with petroleum exploration and extraction, but brine spills can be addressed with proper soil and plant management.
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Oilfield brines, Soil properties, Plant growth