Comparing the growth of fescue and clover plants in petroleum industrial effluents and solutions of similar salinity

Effluents (produced and flow-back waters) from the petroleum industry have been investigated for their potential toxicity to the environment, particularly in regards to chemical composition and salinity. The purpose of this study was to investigate whether their toxicity is any greater than exposure to solutions of similar salinity. The tolerance of Festuca rubra L. (fescue) and Trifolium pratense L. (clover) were investigated for 8 weeks under hydroponic conditions to compare their growth in brine effluents from tertiary recovery operations. Experiments further compared serially-diluted effluents and synthetic solutions (e.g., NaCl/CaCl2) of similar salinities. There were different growth responses to the wastewater and saline solution among both plant species. F. rubra was exhibited a significant higher survival percentage than T. pratense. After four weeks of exposure, T. pratense exhibited greater sensitivity and lethality. Interestingly, biomasses of both plants were greater from industrial wastewater than the comparable brine solution. Although salinity limited plant growth, the tertiary wastewaters contained abundant inorganic and organic substances that may have triggered plant survival and salt-tolerance. F. rubra grew under salts stress, and presented a mechanism to crystalize salt on their leaves. Hence, plant uptake, under certain conditions, may be promoted as an alternative treatment for high salt concentrations.