Effect of EDTA and citric acid on phytoremediation of Cr- B[a]P-co-contaminated soil

Abstract

Polycyclic aromatic hydrocarbons and heavy metals in the environment are a concern, and their removal to acceptable level is required. Phytoremediation, the use of plants to treat contaminated soils, could be an interesting alternative to conventional remediation processes. This work evaluates the role of single and combined applications of chelates to single or mixed Cr + benzo[a]pyrene (B[a]P)-contaminated soil. Medicago sativa was grown in contaminated soil and was amended with 0.3 g citric acid, 0.146 g ethylenediaminetetraacetic acid (EDTA), or their combination for 60 days. The result shows that in Cr-contaminated soil, the application of EDTA + citric acid significantly (p<0.05) decreased the shoot dry matter of M. sativa by 55 % and, as such, decreased the Cr removal potential from the soil. The soluble Cr concentration in single Cr or Cr + B[a]P-contaminated soil was enhanced with the amendment of all chelates; however, only the application of citric acid in Cr-contaminated soil (44 %) or EDTA and EDTA + citric acid in co-contaminated soil increased the removal of Cr from the soil (34 and 54 %, respectively). The dissipation of B[a]P in single B[a]P-contaminated soil was effective even without planting and amendment with chelates, while in co-contaminated soil, it was related to the application of either EDTA or EDTA + citric acid. This suggests that M. sativa with the help of chelates in single or co-contaminated soil can be effective in phytoextraction of Cr and promoting the biodegradation of B[a]P.

Exogenous application of ethylenediamminetetraacetic acid enhanced phytoremediation of cadmium by Brassica napus L.

“…Similarly, many researchers found beneficial effects of EDTA in many crops such as R. globosa, canola, Indian mustard and maize (Najeeb et al 2009;Zhuang et al 2007). Contrarily, decrease in growth, chlorophylls and SPAD value has been observed in many plants with EDTA application under metal stress (Chigbo and Batty 2013). Figure 2 depicts the fluctuations in gas exchange characteristics of B. napus induced by Cd/EDTA alone or in combination in culture medium.…”

“…Exogenous application of EDTA increased heavy metal availability because of its chelating capacity (Chigbo and Batty 2013). The main reason of greater Cd uptake in existence of chelates is possibly due to the fact that roots of plants are able to liberate trace metals from dissolved organometallic complexes (Meers et al 2005), and these lower stability constants of organometallic complexes agreed with greater metal uptake (Han et al 2005).…”

EDTA enhanced plant growth, antioxidant defense system, and phytoextraction of copper by Brassica napus L.

“…We used 2.5 mM EDTA and 50 and 100 μM Cu in the nutrient solution as these concentrations have already been used in the literature such as Azhar et al (2006) and Zhao et al (2010), respectively. EDTA was applied at juvenile stage as already used previously by Chigbo and Batty (2013). The pH was maintained at 6.0±0.1 throughout the experiment when required with 1 M H 2 SO 4 or NaOH.…”

“…Different chelating agents have been used to enhance metal solubility in the soil. Ethylenediaminetetraacetic acid (EDTA) is one of the most effective chelating agents for artificially increasing solubility, complexation, and uptake of Cu and several other toxic metals (Bareen 2012;Chigbo and Batty 2013;Kambhampati 2013;Mani et al 2014). Thus, the addition of EDTA into the soil induces uptake and translocation of heavy metals from the roots to shoots of plants (Meers et al 2008) and is especially important for increased uptake and translocation of toxic metals.…”

Potential of citric acid to alter pH and metal uptake in reeds in acid mine drainage solutions

“…CA has been found to increase the uptake of Cu, Cd and Pb in several plant species (Qu et al . ; Chigbo & Batty ). According to the results of Najeeb et al .…”