Plant responses to toxic elements and salt stress of contamination from the petroleum industry

  • Phatchani Srikhumsuk

Student thesis: Doctoral Thesis


Background & Aims: Several studies have sought to explore the toxicity of heavy metals and high salinity from wastewaters, especially produced water (PW) from the petroleum industry, both in laboratory and field trials; however, there is little information available regarding F. rubra, C. longus, P. australis, and T. pratense species. This thesis investigated these plant species' ability to be used as an alternative method of removing trace elements and salt ions from contaminated soil and water emanating from produced water.;Methodology: Several methods were used to investigate trace elements, in particular, strontium and salt ions. Analysis included the physicochemical characteristics of both soil and water samples. Soil analyses focused on sequential extraction and batch adsorption methods while water samples were used to analyze the value of trace elements and nutrient concentrations. In addition, biomass harvesting and plant material digestion were used to evaluate the phytoremediation technique, which played an essential role in this thesis to explain exposure-response with metal toxicity and high salinity. This work performed investigations mainly using Inductively Coupled Plasma- Optical Emission Spectrometry (ICP-OES) to determine the types and amounts of trace elements.;Results: Freundlich and Langmuir models describe strontium sorption in South Lanarkshire farm in Glasgow, UK, soils. Apparent equilibrium was reached within 24 hours. The interesting thing about the efficiency of F. rubra and T. pratense is their ability to grow and respond quickly. It seems possible that these plants will accumulate strontium composition in their tissues. On the other hand, stressful environments with high salinity of contaminated produced water and similar salinity solutions generated the most concentrated element. However, the results of this study suggested that C. longus and P. australis can absorb and eliminate excess salt ions from their leaves both in produced water and solutions of similar salinity.;Conclusions: The main focus was two-fold: soil and water contamination. Soil was identified as acidic, sodic, slightly silty to coarse sand with low organic matter content. In sorption, Sr ions prefer to associate within residual and carbonate fractions, rather than other fractions in this soil. The best efficiency of retention time for adsorption was more than 24h, which was employed to fit both of the Langmuir and Freundlich equilibria models. Germination tests showed that F. rubra emerged quickly at low concentrations of both calcium and strontium ions; T. pratense responded similarly. The upper parts of T. pratense showed a greater translocation factor of Sr ions than F. rubra. However, in F. rubra, made chlorophyll content adjustments in response to elevated concentrations of strontium in the soils. Therefore, both plants can be considered as accumulator species. On the other hand, species-specific responses to different levels of salinity concentrations were also identified. T. pratense was a more sensitive species than F. rubra in high salinity. In contrast, both C. longus and P. australis were suitable to grow in the high salinity of produced water effluents, illustrating their potential to remove salts in produced waters via salt exclusion.;The results of this study show responses to salt stress and changes in productivity (including death). These findings enhance our understanding of F. rubra, C. longus, P. australis, and T. pratense and their potential uses in mitigation to high salt ions from produced water. Future studies of other potentially useful plant species in this field may also identify important technical difficulties at the genetic or molecular level in salt tolerance of halophyte species.
Date of Award4 Nov 2020
Original languageEnglish
Awarding Institution
  • University Of Strathclyde
SupervisorCharles Knapp (Supervisor) & Joanna Renshaw (Supervisor)

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