Use of phytoremediation techniques for elimination of lead from polluted soils

The effect of chelating agent – EDTA (ethylene-diamine-tetra-acetic acid) was used for induced phytoextraction to increase intensity of lead transfer from roots to aboveground parts of garden pea. Pot experiments with contaminated soil substrata (50 mg Pb.kg-1 and 100 mg Pb.kg-1) were established for experimental purposes in growth chamber. The results showed that application of 5 and 10 mmol EDTA.kg-1 to experimental variants with 100 mg Pb.kg-1 doubled the increase of lead uptake by pea roots in comparison with variants without EDTA addition, which was statistically confirmed. Intensive lead transfer was observed from roots to aboveground parts of pea after application of 5 and 10 mmol EDTA.kg-1 in variant with 50 mg Pb.kg-1 (40-fold increase), as well as in variant with 100 mg Pb.kg-1 (17-fold increase). The results showed that induced phytoextraction can improve the mobility of lead from soil to plant roots. Application of 5 mmol EDTA.kg-1 resulted to 40-fold increase of lead transfer to green plant parts, despite the fact, that garden pea does not belong to conventional metal hyperaccumulating plant species. Following the results, pea could be used for decontamination of arable soil. The optimal EDTA concentration seems to be 5 mmol.kg-1. Therefore, application of 10 mmol EDTA.kg-1 decreased root mass about 55%, which resulted to decrease the intensity of lead uptake.

Determination of Sulfites in Fruit Juices and Meals for Infants and Toddlers

Plants possess various intrinsic mechanisms necessary to accumulate and either sequester or detoxify soil contaminants, including radionuclides. The aim of this study was to determine the bioconcentration factor of two fast growing plants Salvia offlicinalis L. (sage) and Ocimum basillicum L. (basil) that were cultivated in pH neutral soils artificially contaminated with three different concentrations of uranium (211, 352 and 470 mg/kg). The efficiency of citric acid was evaluated with respect to the enhancement of the phytoextraction process. The results showed that the bioconcentration factor did not differ significantly between the selected species (0.01 - 0.03). Citric acid was added in doses (50 mL, 30 mM) until the first effects of uranium phytotoxicity appeared. After four doses of citric acid, the bioconcentration factor reached 0.05 for both plants. The increase of uranium content taken up by the respective plants was more pronounced. Thus, the uranium content of sage grown in contaminated soil (470 mg/kg) increased from 6.03 to 21.28 mg/kg in citric acid-treated soil. The data obtained confirmed the efficiency of citric acid in enhancing phytoextraction of uranium and further suggest that even plants of a rather small biomass can be useful in phytoremediation given the appropriate treatment through induced phytoextraction with appropriate chemical agents.

Study of uranium bioaccumulation capacity of Salvia officinalis L. and Ocimum basilicum L. enhanced by citric acid

Plants possess various intrinsic mechanisms necessary to accumulate and either sequester or detoxify soil contaminants, including radionuclides. The aim of this study was to determine the bioconcentration factor of two fast growing plants Salvia offlicinalis L. (sage) and Ocimum basillicum L. (basil) that were cultivated in pH neutral soils artificially contaminated with three different concentrations of uranium (211, 352 and 470 mg/kg). The efficiency of citric acid was evaluated with respect to the enhancement of the phytoextraction process. The results showed that the bioconcentration factor did not differ significantly between the selected species (0.01 - 0.03). Citric acid was added in doses (50 mL, 30 mM) until the first effects of uranium phytotoxicity appeared. After four doses of citric acid, the bioconcentration factor reached 0.05 for both plants. The increase of uranium content taken up by the respective plants was more pronounced. Thus, the uranium content of sage grown in contaminated soil (470 mg/kg) increased from 6.03 to 21.28 mg/kg in citric acid-treated soil. The data obtained confirmed the efficiency of citric acid in enhancing phytoextraction of uranium and further suggest that even plants of a rather small biomass can be useful in phytoremediation given the appropriate treatment through induced phytoextraction with appropriate chemical agents.

Effect of biodegradable chelators on induced phytoextraction of uranium- and cadmium- contaminated soil by Zebrina pendula Schnizl

This study investigated the effect of ethylenediamine-N,N′-disuccinic acid (EDDS), oxalic acid (OA), and citric acid (CA) on phytoextraction of U- and Cd-contaminated soil by Z. pendula. In this study, the biomass of tested plant inhibited significantly following treatment with the high concentration (7.5 mmol·kg−1) EDDS treatment. Maximum U and Cd concentration in the single plant was observed with the 5 mmol·kg−1 CA and 7.5 mmol·kg−1 EDDS treatment, respectively, whereas OA treatments had the lowest U and Cd uptake. The translocation factors of U and Cd reached the maximum in the 5 mmol·kg−1 EDDS. The maximum bioaccumulation of U and Cd in the single plants was 1032.14 µg and 816.87 µg following treatment with 5 mmol·kg−1 CA treatment, which was 6.60- and 1.72-fold of the control groups, respectively. Furthermore, the resultant rank order for available U and Cd content in the soil was CA > EDDS > OA (U) and EDDS > CA > OA (Cd). These results suggested that CA could greater improve the capacity of phytoextraction using Z. pendula in U- and Cd- contaminated soils.

Insights into Heavy Metals Leakage in Chelator-Induced Phytoextraction of Pb- and Tl-Contaminated Soil

Chelators including DTPA (diethylene triamine pentaacetic acid) and oxalic acid were selected for inducing phytoextraction of heavy metals (HMs) from Pb-, Tl-, and Pb-Tl- contaminated soil, in which heavy metals leakage was highly remarkable. Results showed that compared with the control group without chelating agent under planting conditions, the extraction efficiency (i.e., uptake coefficient) of Pb, Tl increased by 86%, 43% from Pb-Tl- contaminated soil in the presence of oxalic acid, and there was no significant change in heavy metal leakage under rainfall conditions. It was the best phytoremediation scheme in this work. Under rainfall conditions, the HMs concentration in the leachate showed a linear decreasing trend. Acid rain promoted the leakage of heavy metals, and the average leached amount of Tl increased by 1.47 times under acid rain conditions. However, for Pb, DTPA was the main influencing factor, followed by acid rain.