Bigot, M, Guterres, J, Rossato, L, Pudmenzky, A, Doley, D, Whittaker, M, Pillai-McGarry, U & Schmidt, S 2012, 'Novel metal-binding hydrogel particles alleviate soil toxicity and facilitate healthy plant establishment of the native metallophyte grass Astrebla lappacea in mine waste rock and tailings', in AB Fourie & M Tibbett (eds), Proceedings of the Seventh International Conference on Mine Closure
, Australian Centre for Geomechanics, Perth, pp. 533-549.
Soil contaminants are potentially a major threat to human and ecosystem health and sustainable production of food and energy where mineral processing wastes are discharged into the environment. It is rarely possible to totally stabilise, render harmless or remove toxic metals from these wastes. Metallophytes (metal-tolerant plants) have evolved mechanisms to survive on many natural metal-rich soils and mining wastes. However, in extreme conditions, metal concentrations in soils/wastes often exceed even the metal-tolerance thresholds of metallophytes and the sites remain barren with high risks of contaminant leaching and dispersion into the environment via erosion. A novel soil amendment based on micron-size thiol functional cross-linked acrylamide polymer hydrogel particles (X3) binds toxic soluble metals irreversibly and significantly reduces their concentrations in the soil solution to below the phytotoxicity thresholds. X3 thoroughly mixed with the surface soil layer (top 50 mm) of toxic mine waste materials in pots in glasshouse conditions successfully reduced total soluble concentrations of major contaminants in waste rock (aluminium (Al), copper (Cu), zinc (Zn), cobalt (Co) and manganese (Mn)) and tailings (sodium (Na), sulphur (S), Zn, Mn, Co and cadmium (Cd)) by 90.3 to 98.7% in waste rock, and 88.6 to 96.4% in tailings immediately after application. Soil solution pH was significantly increased from 2.5–3.8 and from 7.1–7.7 in X3-amended waste rock and tailings, respectively. Salinity of the soil solutions (assessed via electrical conductivity (EC) measurements) decreased significantly from 12.4–3.5 and from 81–14 mS.cm-1 in X3-amended waste rock and tailings, respectively. After 61 days, the quality of the unamended bottom layer of the X3-treated pots was also improved and showed significant increase in pH and reduction of metal concentrations by 91.6 to 95.6% in waste rock and 64.9 to 84.1% in tailings, as well as reductions of EC in both mine substrates and reduction of saline element concentrations (Na and S) by 69 to 74% in the tailings particularly. Furthermore, the combination of X3 and metallophytes was more efficient at improving soil solution quality than X3 alone. The addition of X3 to the substrates increased substrate water retention and water availability to plants by up to 108% and 98% for waste rock and tailings respectively via a substantial reduction in salinity, while it significantly decreased substrate penetration resistance allowing easier root penetration in surface soil. Soil quality improvement by X3 allowed successful early establishment of the native metallophyte grass, Astrebla lappacea, on both waste rock and tailings where plants failed to establish otherwise. In X3-amended waste rock, plant establishment percentage (45%) was not significantly different from the amended sand control (41%). Although X3-amended tailings had lower establishment percentages (35%) than the amended sand control (61%), plants had established at a satisfactory percentage when compared to unamended tailings treatments (0%). No toxicity or deficiency symptoms were observed on leaves throughout the experiment. The X3 remediation technique promises to be very robust and applicable to a wide range of situations where decades of attempted plant establishment had previously been unsuccessful.
ASEC (2001) Australian State of the Environment Committee, Australia State of the Environment 2001, Collingwood, Victoria, p. 71.
Baker, A.J.M. (1981) Accumulators and excluders – strategies in the response of plants to heavy metals, Journal of Plant Nutrition, Vol. 3, pp. 643–654.
Baker, A.J.M. (1987) Metal tolerance, New Phytologist, Vol. 106 (Suppl.), pp. 93–111.
Bohn, H.L. (1971) Redox potentials, Soil Science, Vol. 112, pp. 39–45.
Brady, N.C. and Weil, R.R. (2004) Elements of the nature and properties of soils, Pearson Education.
Campbell, M.H. and Swain, F.G. (1973) Effect of strength, tilth and heterogeneity of the soil surface on radicle-entry of surface-sown seeds, Grass and Forage Science, Vol. 28, pp. 41–50.
CSIRO (2004) CSIRO Sustainability Network, Network Letter 46E, Australia, 24 p., viewed 7 March 2011,
Cunningham, S. and Berti, W. (1993) Remediation of contaminated soils with green plants: an overview, In Vitro Cellular & Developmental Biology – Plant, Vol. 29, pp. 207–212.
de Varennes, A., Cunha-Queda, C. and Ramos, A.R. (2009) Polyacrylate polymers as immobilizing agents to aid phytostabilization of two mine soils, Soil Use and Management, Vol. 25, pp. 133–140.
de Varennes, A., Goss, M.J. and Mourato, M. (2006) Remediation of a sandy soil contaminated with cadmium, nickel, and zinc using an insoluble polyacrylate polymer, Communications in Soil Science and Plant Analysis, Vol. 37, pp. 1,639–1,649.
de Varennes, A. and Torres, M.O. (1999) Remediation of a long-term copper-contaminated soil using a polyacrylate polymer, Soil Use and Management, Vol. 15, pp. 230–232.
Delaune, R.D., Pezeshki, S.R. and Pardue, J.H. (1990) An oxidation-reduction buffer for evaluating the physiological response of plants to root oxygen stress, Environmental and Experimental Botany, Vol. 30, pp. 243–247.
Dorraji, S.S., Golchin, A. and Ahmadi, S. (2010) The Effects of hydrophilic polymer and soil salinity on corn growth in sandy and loamy soils, CLEAN – Soil, Air, Water, Vol. 38, pp. 584–591.
Garau, G., Castaldi, P., Santona, L., Deiana, P. and Melis, P. (2007) Influence of red mud, zeolite and lime on heavy metal immobilization, culturable heterotrophic microbial populations and enzyme activities in a contaminated soil, Geoderma, Vol. 142, pp. 47–57.
Guiwei, Q., De Varennes, A. and Cunha-Queda, C. (2008) Remediation of a mine soil with insoluble polyacrylate polymers enhances soil quality and plant growth, Soil Use and Management, Vol. 24, pp. 350–356.
Guterres, J., Rossato, L., Pudmenzky, A., Doley, D., Whittaker, M. and Schmidt, S. (2012) Micron-size metal-binding hydrogel particles improve germination and radicle elongation of Australian metallophyte grasses in mine waste rock and tailings, (2012) in Proceedings Seventh International Conference on Mine Closure (Mine Closure 2012), A.B. Fourie and M. Tibbett (eds), 25‒27 September 2012, Brisbane, Australia, Australian Centre for Geomechanics, Perth, pp. 517–532.
Haling, R.E., Simpson, R.J., Culvenor, R.A., Lambers, H. and Richardson, A.E. (2011) Effect of soil acidity, soil strength and macropores on root growth and morphology of perennial grass species differing in acid-soil resistance, Plant Cell and Environment, Vol. 34, pp. 444–456.
Hüttermann, A., Orikiriza, L.J.B. and Agaba, H. (2009) Application of superabsorbent polymers for improving the ecological chemistry of degraded or polluted lands. CLEAN – Soil, Air, Water, Vol. 37, pp. 517–526.
Johnson, M.S. (1984) Effect of soluble salts on water absorption by gel-forming soil conditioners. Journal of the Science of Food and Agriculture, Vol. 35, pp. 1,063–1,066.
Khan, M.J. and Jones, D.L. (2009) Effect of composts, lime and diammonium phosphate on the phytoavailability of heavy metals in a copper mine tailing soil, Pedosphere, Vol. 19, pp. 631–641.
Klute, A. (1986) Water retention: laboratory methods, Methods of soils analysis, Part 1, 2nd edition, A. Klute, Agronomy monographs, Vol. 9, ASA and SSSA Madison, Wisconsin, pp. 597–618.
Kramer, P.J. and Boyer, J.S. (1995) Water relations of plants and soils, Academic Press, San Diego/Sydney.
Lasat, M.M. (2000) Phytoextraction of metals from contaminated soil: a review of plant/soil/metal interaction and assessment of pertinent agronomic issues, Journal of Hazardous Substance Research, Vol. 2, pp. 1–25.
Letey, J., Clark, P. and Amrhein, C. (1992) A greenhouse experiment finds water-sorbing polymers do not conserve water, California Agriculture, Vol. 46, pp. 9–10.
Levy, G.J., Ben-Hur, M. and Agassi, M. (1991) The effect of polyacrylamide on runoff, erosion, and cotton yield from fields irrigated with moving sprinkler systems, Irrigation Science, Vol. 12, pp. 55–60.
Loring, D.H. and Rantala, R.T.T. (1992) Manual for the geochemical analyses of marine sediments and suspended particulate matter, Earth-Science Reviews, Vol. 32, pp. 235–283.
Lottermoser, B.G. (2010) Introduction to mine wastes, Mine wastes, Springer Berlin Heidelberg, pp. 1–41.
LPSDP (2006) Mine rehabilitation: Leading Practice Sustainable Development Program for the Mining Industry, Department of Industry, Tourism and Resources, Canberra, ACT, Australia.
Mendez, M.O. and Maier, R.M. (2008a) Phytostabilization of mine tailings in arid and semiarid environments – an emerging remediation technology, Environmental Health Perspectives, Vol. 116, pp. 278–283.
Mendez, M.O. and Maier, R.M. (2008b) Phytoremediation of mine tailings in temperate and arid environments, Reviews in Environmental Science and Biotechnology, Vol. 7, pp. 47–59.
Menzies, N.W., Donn, M.J. and Kopittke, P.M. (2007) Evaluation of extractants for estimation of the phytoavailable trace metals in soils, Environmental Pollution, Vol. 145, pp. 121–130.
Mulligan, C.N., Yong, R.N. and Gibbs, B.F. (2001) Remediation technologies for metal-contaminated soils and groundwater: an evaluation, Engineering Geology, Vol. 60, pp. 193–207.
Mulvey, P.J. and Elliott, G.L. (2000) Toxicities in soils, Soils: their properties and management, 2nd Edition, P.E.V. Charman and B.W. Murphy (eds), Oxford University Press, South Melbourne, Australia.
Mushtaq, Y.K. (2011) Effect of nanoscale Fe3O4, TiO2 and carbon particles on cucumber seed germination, Journal of Environmental Science and Health, Part A, Vol. 46, pp. 1,732–1,735.
Orts, W.J., Sojka, R.E., Glenn, G.M. and Gross, R.A. (1999) Preventing soil erosion with polymer additives. Polymer News, 24, pp. 406-413.
Pimentel, D. (2006) Soil erosion: a food and environmental threat, Environment, Development and Sustainability, Vol. 8, pp. 119–137.
Pudmenzky, A., Rossato, L., Doley, D., Ramirez, C. and Baker, A.J.M. (2009) Development of a metallophyte spatial database covering Australia, Mine Closure 2009: Fourth International Seminar on Mine Closure, A. Fourie and M. Tibbett (eds), Australian Centre for Geomechanics, Perth, WA, Australia.
Rayment, G.E. and Higginson, F.R. (1992) Australian laboratory handbook of soil and water chemical methods, Inkata Press, Melbourne/Sydney.
Rensing, C. and Maier, R.M. (2003) Issues underlying use of biosensors to measure metal bioavailability, Ecotoxicology and Environmental Safety, Vol. 56, pp. 140–147.
Rossato, L., MacFarlane, J., Whittaker, M., Pudmenzky, A., Doley, D., Schmidt, S. and Monteiro, M.J. (2011) Metal-binding particles alleviate lead and zinc toxicity during seed germination of metallophyte grass Astrebla lappacea, Journal of Hazardous Materials, Vol. 190, pp. 772–779.
Salt, D.E., Blaylock, M., Kumar, N.P.B.A., Dushenkov, V., Ensley, B.D., Chet, I. and Raskin, I. (1995) Phytoremediation: a novel strategy for the removal of toxic metals from the environment using plants, Biotechnology, Vol. 13, pp. 468–474.
Sauvé, S., Hendershot, W. and Allen, H.E. (2000) Solid-solution partitioning of metals in contaminated soils: Dependence on pH, total metal burden, and organic matter, Environmental Science & Technology, Vol. 34, pp. 1,125–1,131.
Sayed, H.E., Kirkwood, R.C. and Graham, N.B. (1991) The effects of a hydrogel polymer on the growth of certain horticultural crops under saline conditions, Journal of Experimental Botany, Vol. 42, pp. 891–899.
Shi, Y., Li, J., Shao, J., Deng, S.R., Wang, R.G., Li, N.Y., Sun, J., Zhang, H., Zhu, H.J., Zhang, Y.X., Zheng, X.J., Zhou, D.Z., Huttermann, A. and Chen, S.L. (2010) Effects of Stockosorb and Luquasorb polymers on salt and drought tolerance of Populus popularis, Scientia Horticulturae, Vol. 124, pp. 268–273.
Sinha, R., Herat, S. and Tandon, P.K. (2007) Phytoremediation: role of plants in contaminated site management, Environmental Bioremediation Technologies, S. Singh and R. Tripathi (eds), Springer Berlin Heidelberg, pp. 315–330.
Sojka, R.E., Bjorneberg, D.L., Entry, J.A., Lentz, R.D. and Orts, W.J. (2007) Polyacrylamide in agriculture and environmental land management, Advances in Agronomy, L.S. Donald (ed), Academic Press, pp. 75–162.
Suttar, S. (1990) Ribbons of blue handbook, Scitech, Victoria, Australia.
Taylor, H.M. and Brar, G.S. (1991) Effect of soil compaction on root development, Soil and Tillage Research, Vol. 19, pp. 111–119.
The State of Queensland (2011) Salinity management handbook, second edition, Department of Environment and Resource Management, Brisbane, Australia.
Whiting, S.N., Reeves, R.D., Richards, D., Johnson, M.S., Cooke, J.A., Malaisse, F., Paton, A., Smith, J.A.C., Angle, J.S., Chaney, R.L., Ginocchio, R., Jaffre, T., Johns, R., McIntyre, T., Purvis, O.W., Salt, D.E., Schat, H., Zhao, F.J. and Baker, A.J.M. (2004) Research priorities for conservation of metallophyte biodiversity and their potential for restoration and site remediation, Restoration Ecology, Vol. 12, pp. 106–116.
Wong, M.H. (2003) Ecological restoration of mine degraded soils, with emphasis on metal contaminated soils, Chemosphere, Vol. 50, pp. 775–780.
Woodhouse, J.M. and Johnson, M.S. (1991) The effect of gel-forming polymers on seed germination and establishment, Journal of Arid environments, Vol. 20, pp. 375–380.