Research student profile: Nabeel Niazi

Project title

Arsenic contamination in soils of NSW, Australia: speciation, bioavailability and remediation.

Project overview

My research interests are to determine (1) the phytoremediation capacity of Chinese brake fern (Pteris vittata L.) and gold dust fern (Pityrogramma calomelanos var. austroamericana) for the remediation of an arsenic contaminated site; (2) the speciation and bioavailability of arsenic in historically contaminated soils using a sequential extraction procedure and synchrotron based X-ray absorption near edge structure (XANES) spectroscopy. In addition to that, I am also interested to develop a soil sampling scheme using geostatistical methods to evaluate the spatial variability pattern of As in soil surrounding the cattle dip sites in northern NSW, Australia.

The restoration of As contaminated sites is imperative due to the highly toxic and carcinogenic nature of the contaminant. Phytoremediation of As contaminated soil using As hyperaccumulating ferns has emerged as a cost effective and environmentally friendly remediation technology. Recently, gold dust fern was identified as an As hyperaccumulator in Australia, and this species has shown a consistent As hyperaccumulation pattern in the glasshouse studies. Therefore, it was vital to determine the potential of gold dust fern against the well-established Chinese brake fern under the field conditions.
Similarly, it is also very important to evaluate the bioavailability of As in the contaminated soils. X-ray absorption fine structure (XAFS) spectroscopy has been used to determine the solid-phase speciation of the mining contaminated sites, and sequential extraction procedures have been employed to evaluate bioavailability of As in the contaminated soils. To our knowledge, no research has been performed where both these techniques have been used together to determine the speciation and bioavailability of As in soils collected from pesticides and herbicides impacted sites. In this study we will try to figure out the limitation and advantages of both the methods to assess the bioavailability of As, and this information will be helpful for the site specific risk assessment and for the development of suitable management and remediation strategies.

Ferns have been grown from spores in the glass house for a period of 6-8 months and then shifted in the field for phytoremediation experiment. The As in soils and plant samples was analysed using ICP-AES.
I have used Brassica juncea (Indian Mustard) as a test plant for my glass house bioavailability trial. The X-ray absorption near edge structure (XANES) spectroscopy work for As speciation was done at Photon Factory, Tsukuba, Japan.

The results indicated that gold dust fern performed much better than the Chinese brake fern in the field and extracted more than twice As from soil as compared to Chinese brake fern. These results are contrary to our earlier glasshouse studies and suggest that field conditions are imperative to assess the phytoremediation capability of the As hyperaccumulating ferns.
The results from speciation and bioavailability experiment revealed that sequential extraction procedure was better as compared to XANES spectroscopy to determine the bioavailability of As for the highly mobile portions. XANES overlooked these As fractions and underestimated the bioavailability of As, especially where As was mostly bound in the mobile fractions. However, XANES spectroscopy was better to determine the association of As with various chemical species (e.g., Fe oxides) and the mineral forms of As (e.g. orpiment, scorodite); this technique is better to provide the fingerprint information. Combining both the techniques give us a protocol to evaluate the site specific speciation of As and this information can be efficiently used for the assessment of As bioavailability and the development of suitable management strategies.

Background

I am an international student from Pakistan. I completed my B.Sc (Hons) Agri in 2004 (Soil Science) at University of Agriculture, Faisalabad, and then did my M.Sc (Hons) Agri in 2006, selecting Soil Science as major, from Institute of Soil and Environmental Sciences, University of Agriculture, Faisalabad. I have submitted a thesis for my Master's degree and my work was on studying the “Growth Response of Rice to Cu and Zn Application in Saline-sodic Soil Conditions”. I started my PhD at the University of Sydney, in March 2008.

I have been granted a scholarship by Higher Education Commission of Pakistan.

I have won 3rd best prize for presenting my paper at the International Conference on Phytotechnologies, Parma, Italy, 26–29 September, 2010 (see the reference number 7 below).

Publications

  • Niazi NK, Singh B, Zwieten LV and Kachenko, AG (2010) Arsenic hyperaccumulation by ferns: a field study in northern NSW. Published paper in the Proceedings of the 19th World Congress of Soil Science on Soil Solutions for the Changing World. Brisbane, Australia, 1–6 August 2010.
  • Niazi NK, Singh B, Zwieten LV and Kachenko, AG (2010) Field evaluation of hyperaccumulating ferns to remediate an arsenic contaminated soil. Nursery & Garden Industry National Conference. Darwin, Australia, 19–22 April 2010. (Poster presentation).
  • Niazi NK, Singh B, Shah, P (2010) Speciation and bioavailability of arsenic in contaminated soils using X-ray absorption near edge structure spectroscopy and a sequential extraction procedure. Proceedings of the ConSoil International Conference on the Management of Groundwater, Soil & Sediments. Salzburg, Austria, 21–24 September, 2010. (Oral presentation).
  • Niazi NK, Bishop T, Singh B, (2010) Comparative study for the arsenic hyperaccumulation by ferns: a model-based geostatistical approach. Proceedings of the ConSoil International Conference on the Management of Groundwater, Soil & Sediments. Salzburg, Austria, 21–24 September, 2010. (Poster presentation).
  • Niazi NK, Singh B, Bishop T, Zwieten LV and Kachenko, AG (2010) Environmentally friendly approach to clean-up arsenic contaminated soils. The ‘Centenary Research Symposium’ of The Faculty of Agriculture, Food and Natural Resources, The University of Sydney on Friday 4 June 2010. (Poster presentation).
  • Niazi NK, Singh B, Zwieten LV and Kachenko, AG (2010) A comparative study to evaluate the phytoremediation potential of two fern species for the remediation of an arsenic contaminated site under field conditions. The International Conference on Phytotechnologies. Parma, Italy, 26–29 September, 2010. (Oral presentation).
  • Niazi NK, Singh B, Bishop, T (2010) A geostatistical model based approach to evaluate spatial variability of arsenic in soil and to compare arsenic-hyperaccumulation efficiency of two fern species. The International Conference on Phytotechnologies. Parma, Italy, 26–29 September, 2010. (Poster presentation: Won 3rd prize).
  • Niazi NK, Singh B, Zwieten LV and Kachenko, AG (2010) Phytoremediation potential of Pityrogramma calomelanos var. austroamericana and Pterris vittata L. grown at a highly variable arsenic contaminated site. (Submitted to International Journal of Phytoremediation)

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