Stabilization of metals in acidic mine spoil with amendments and red fescue (Festuca rubra L.) growth

Abstract

Stabilization of metals with amendments and red fescue (Festuca rubra, cv. Keszthelyi 2) growth was studied on an acidic and phytotoxic mine spoil (pH(KCl) 3.20-3.26; Cd 7.1 mg kg(-1), Cu 120 mg kg(-1), Pb 2154 mg kg(-1) and Zn 605 mg kg(-1)) from Gyöngyösoroszi, Hungary in a pot experiment. Raising the pH above 5.0 by lime (CaCO(3)), and supplementing with 40 mg kg(-1)nitrogen (NH(4)NO(3)) made this material suitable for plant growth. All cultures were limed with 0.5% (m/m) CaCO(3) (treatment 1), which was combined with 5% (m/m) municipal sewage sludge compost (treatment 2), 5% (m/m) peat (treatment 3), 7.5% (m/m) natural zeolite (clinoptilolite) (treatment 4), and 0.5 (m/m) KH(2)PO(4) (treatment 5). Treatments 1-5 were combined with each other (treatment 6). After 60 days of red fescue growth, pH of the limed mine spoil decreased in all cultures units. Application of peat caused the highest pH decrease (1.15), while decrease of pH was less than 0.23 in treatments 2, 5 or 6. Application of lime significantly reduced concentrations of metals in the 'plant available' fraction of mine spoil compared to non-limed mine spoil. Amendments added to limed mine spoil changed variously the ratio of Cd, Cu, Pb and Zn in exchangeable or 'plant available' fractions, differently influencing the phytoavailability of these metals. Most of the metals were captured in the roots of test plants. Treatment 2 caused the appearance of less Cd in shoots (<0.1 microg g(-1)) or roots (3.11 microg g(-1)), while treatment 5 resulted in the highest Cd concentration (2.13 microg g(-1)) in shoots. Treatments did not influence significantly the Cu accumulation in shoots. The Pb accumulation of roots (44.7 microg g(-1)) was most effectively inhibited by combined treatment, while the highest value (136 microg g(-1)) was found in the culture treated with potassium phosphate. Pb concentration in shoots was below the detection limit, except for treatments 5 and 6. Peat application resulted in higher Zn concentration (448 microg g(-1)) in shoots than other amendments, where these values were around 100 microg g(-1). All amendments influenced positively the dry matter yield of red fescue grown in limed mine spoil, however the application of 0.5 phosphate was less favourable. Liming, application of amendments and growth of red fescue can stabilize metals in acidic and phytotoxic mine spoil, and by phytostabilization they can reduce the risk of metal contamination of the food chain.

Stabilisation of metals in mine spoil with amendments and growth of red fescue in symbiosis with mycorrhizal fungi

“…Mine spoil sampling, mixing, drying, screening, elemental analysis, determination of pH and liming were detailed in our former publication (Simon 2005). Addition of 1.0% (m/m) CaCO 3 (puriss., Reanal Ltd., Hungary) to this acidic mine spoil raised the pH above 6.5, which is suitable for plant growth.…”

“…Addition of 1.0% (m/m) CaCO 3 (puriss., Reanal Ltd., Hungary) to this acidic mine spoil raised the pH above 6.5, which is suitable for plant growth. Municipal sewage sludge compost and natural zeolite origin and their mixing to mine spoil were described in Simon (2005). Pellets with spores of Zn-tolerant arbuscular mycorrhizal fungi (Glomus intraradices BrI isolate, Glomeromycota, Glomerales; Inox GmbH, Germany) were used as mycorrhizal inoculants (Hildebrandt et al 1999).…”

“…Limed mine spoil was thereafter incubated for 9 weeks in room temperature receiving distilled water weekly to reach a constant weight (1250 grams). pH in mine spoil was determined before seeding and at the end of the pot experiment (Simon 2005).…”

“…Keszthelyi 2) in a growth chamber of the College of Nyíregyháza, Hungary. Light, temperature, humidity, water and nitrogen supply were controlled (Simon 2005). In every pot 0.6 g red fescue seeds were planted.…”

“…Nitric acid extractions of this mine spoil revealed that the highest concentrations of Cd, Cu, Pb and Zn are 55, 9000, 16 500 and 42 000 mg/kg (Kovács and Tamás 2002). During our previous pot experiment with red fescue we found that raising the pH of this strongly acidic mine spoil with lime (CaCO 3 ) and application of ammonium nitrate made this phytotoxic material suitable for plant growth (Simon 2005). Among tested amendments lime, municipal sewage sludge compost and natural zeolite had the best metal stabilisation effects in mine spoil, and reduced best the phytoavailability of metals (Simon 2005).…”