Indukált fitoextrakció alkalmazása extrémen szennyezett földszeru anyagon

Translated title of the contribution: Application of phytoremediation on extremely contaminated soils

Andrea Farsang, Viktória Cser, Károly Barta, Gábor Mezosi, László Erdei, Bernadett Bartha, István Fekete, Edina Pozsonyi

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4 Citations (Scopus)

Abstract

Phytoremediation is a promising new method for decreasing water and soil pollution. It involves various technologies capable of decreasing the concentration of pollutants in the soil or stabilizing their transport at an acceptable risk level with help of special plants and associated microbes. The aim was to model the possibility of applying phytoremediation in the case of extreme soil contamination. Work was continued in various directions: various techniques were used to determine the heavy metal content of a contaminated soil in Almásfüzito (NW Hungary), while a special sequential technique was used to separate element fractions with different mobility rates. In the course of a pot experiment the toxic substances in contaminated peat mixed with various ratios of lake mud (1:1, 1:2, 2:1, 3:1) were reduced by phytoremediation using a suitable chelating agent. The following conclusions were drawn from the results: - The temperature conditions recording on the experimental plots and the soil parameters important for the soil-water-plant association were indicative of an extreme habitat and soil conditions: high pH, and extreme water and heat regimes. - The "total" heavy metal content of the experimental soils (soluble in nitrohydrochloric acid) greatly exceeded the Hungarian limit values for all seven metals investigated. The high heavy metal content inhibited plant development. To eliminate this problem various dilutions were used in the pot experiment, by mixing the contaminated soil with lake mud free of heavy metals. - In order to separate element fractions with different mobility rates and to determine the quantity of chelating agents required for phytoremediation, sequential analysis was performed. In the course of the extraction process five metals were analysed: Cd, Ni, Zn, Cu and Pb. Based on the availability of the metal content, the least mobile element in the samples was Pb (0-5%), followed by Cu (10-20%), Ni (20-30%) and Zn and Cd (40-60%). - In response to treatment with chelating agents the quantity of heavy metal extracted by the plants rose in half the samples. This increase was generally 8-30%, but all expectations were exceeded by tall fescue, which extracted 174% Cu and 146% Zn in the 2:1 dilution. For both sunflower and tall fescue the 1:1, 2:1 and 1:2 mixtures of contaminated soil:lake mud proved the most effective, but as the analyses involved only four independent parallel samples for the mixing ratios and two for the plant species, the results can only be interpreted as a trend. - When monitoring changes in the soil, the element content of the topsoil (the part influenced by the phytoremediation process) was compared with that of the soil in the bottom third of the pots. The greatest reduction in concentration in the topsoil was observed when the mixing ratio was 2:1, i.e. when two parts of contaminated soil were mixed with one part of lake mud. In this case the very high element content provided a satisfactory basis for plant microelement uptake, but the addition of lake mud caused a great improvement in the soil parameters and available nutrient content of the "soil". Table 1. Treatments in the pot experiment set up using contaminated soil from Almásfüzito and lake mud. (1) Sample No. (2) Mixing ratio. (3) Plant. a) Tall fescue (Festuca arundinacea); b) Sunflower (Helianthus annuus). Note: szt: Contaminated "soil"; ti: Lake mud; Italics: treated with chelating agents. Table 2. Main soil and hydrological characteristics of the plots. (1) Characteristic. a) Upper limit of plasticity according to Arany; b) soil texture; c) Organic matter content; d) Carbonate content; e) Maximum water capacity; f) Field capacity; g) Bulk density; h) Soil density. (2) Plot No. Note: HV: sandy loam. Table 3. Heavy metal content in the soil-like material in Almásfüzito. (1) Element. (2) Measured concentration. (3) Environmental limit value "B", based on extraction with aqua regia, mg/kg. Table 4. Heavy metal ratios of the sample plots in Almásfü zito after sequential analysis, based on the data of 12 homogenized mean samples. (1) Metal. (2) Statistical parameter. a) Mean; b) Standard deviation. (3) Mobile. (4) Bound to Fe-Mn-oxide. (5) Bound to organic matter. (6) Heavy metal fraction soluble in concentrated acid, mg/kg. Note: *Not evaluable statistically as the metal contents were below the detection limit. Table 5. Zn, Cu and Cd content (?g/g) of mean samples from the pot experiment after extraction according to the Lakanen-Erviö method (LE) and with aqua regia (KV). (1) Mixing ratio. a) Polluted soil (szt); b) Lake mud (ti); c) Mean; d) Standard deviation. Note: Based on 2 independent replications for szt and ti samples and 4 independent replications for the mixing ratios. Table 6. Mean values of the dry biomass in the pots (2 parallel samples for each plant). (1) Pot No., mixing ratio (contaminated soil:lake mud), plant. a) Tall fescue; b) sunflower. (2) Mean dry matter content, g. Table 7. Cu and Zn content of the soil sampled at two depths of the pot (0-5 cm and 15-20 cm) after treatment (3 parallel measurements per sample). (1) Pot No. (2) Plant. (3) Mean. (4) Standard deviation. Fig. 1. Preparation of the study plots. Fig. 2. Percentage distribution of the heavy metal contents obtained by sequential extraction for the contaminated soil-like material of the study plots (based on the data of 12 homogenized mean samples). a) Mobile; b) Bound to Fe-Mn-oxide; c) Bound to organic matter; d) soluble in concentrated acid. Fig. 3. Cu content in Helianthus annuus and Festuca arundinacea before (a) and after (b) treatment with chelating agents (mean of 3 parallel measurements per sample). Values of standard deviation are between 0.01 and 0.05. Fig. 4. Zn content of the soil sampled at two depths of the pot (0-5 cm and 15-20 cm) (mean of 3 parallel measurements per sample).

Original languageHungarian
Pages (from-to)317-332
Number of pages16
JournalAgrokemia es Talajtan
Volume56
Issue number2
DOIs
Publication statusPublished - Dec 1 2007

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ASJC Scopus subject areas

  • Agronomy and Crop Science
  • Soil Science

Cite this

Farsang, A., Cser, V., Barta, K., Mezosi, G., Erdei, L., Bartha, B., Fekete, I., & Pozsonyi, E. (2007). Indukált fitoextrakció alkalmazása extrémen szennyezett földszeru anyagon. Agrokemia es Talajtan, 56(2), 317-332. https://doi.org/10.1556/Agrokem.56.2007.2.9