Behavior of mercury in a soil–plant system as affected by inoculation with the arbuscular mycorrhizal fungus Glomus mosseae

Abstract

Effects of inoculation with the arbuscular mycorrhizal (AM) fungus Glomus mosseae on the behavior of Hg in soil-plant system were investigated using an artificially contaminated soil at the concentrations of 0, 1.0, 2.0, and 4.0 mg Hg kg −1 . Mercury accumulation was lower in mycorrhizal roots than in nonmycorrhizal roots when Hg was added at the rates of 2.0 and 4.0 mg kg −1 , while no obvious difference in shoot Hg concentration was found between mycorrhizal and nonmycorrhizal treatments. Mycorrhizal inoculation significantly decreased the total and extractable Hg concentrations in soil as well as the ratio of extractable to total Hg in soil. Equilibration sorption of Hg by soil was investigated, and the results indicated that mycorrhizal treatment enhanced Hg sorption on soil. The uptake of Hg was lower by mycorrhizal roots than by nonmycorrhizal roots. These experiments provide further evidence for the role of mycorrhizal inoculation in increasing immobilization of Hg in soil and reducing the uptake of Hg by roots. Calculation on mass balance of Hg in soil suggests the presence of Hg loss from soil presumably through evaporation, and AM inoculation enhanced Hg evaporation. This was evidenced by a chamber study to detect the Hg evaporated from soil.

The Role of Arbuscular Mycorrhizal Fungus (Gigaspora margarita) on Mercury and Nutrients Accumulation by Enterolobium cyclocarpum Seedlings

“…We predicted that decreasing Hg content in roots is one of Hg tolerance mechanisms in mycorrhizal symbiosis. This result was in line with Yu et al (2010), AMF Glomus mosseae decreased significantly Hg concentration in maize roots when Hg -1 was applied at the rates of 2.0 dan 4.0 mg kg . All interactions of Hg with soil/growth media, roots, and AMF influence its uptake by plants, but this presume need to be investigated in further research.…”

“…This finding is in line with Rabie (2005) who reported that sensitivity of AM symbionts to heavy metal polluted soil expressed as a reduction in root colonization. In contrast, addition of Hg in soil did not significantly influence maize root colonization rate (Yu et al 2010). Another interesting result showed at Table 7, the presence of AMF could increase the metal tolerance index of E. cyclocarpum seedlings compared with nonmycorrhizal seedlings when they treated with 750 µM Hg.…”

“…Therefore, the potential of AMF has not yet been fully explored with respect to its Hg phytoremediation. The first report about the effects of AM inoculation on Hg behavior in soil-plant system is done by Yu et al (2010) and it has been shown that Hg uptake was lower by mycorrhizal roots of maize than by non-mycorrhizal roots. Hg accumulation in several plants has been studied, such as white clover (Greger et al 2005), alfalfa (Ortega-Villasante et al 2005), lentil, chickpea (Rodríguez et al 2007) and common vetch (Sierra et al 2008).…”

Effect of arbuscular mycorrhizal fungi on the potential of three wild plant species for phytoextraction of mercury from small-scale gold mine tailings

“…Results of statistical analysis, however, showed that AM fungi inoculation did not significantly affect the accumulation of mercury. This might indicate a loss of Hg which can be attributed to Hg volatilization as a result of AM fungi influence (Yu et al, 2010). All treatments posed TF values of more than 1, i.e.…”

“…It is thought that the bioavailability of mercury in the rooting zones of the three plant species declined into a form that was less soluble as absorbed by organic compounds released by plant roots, or absorb the metal into the root surface, and then accumulated the metal in the plant tissues (Berti and Cunningham, 2000;Wong, 2003). Outside the roots, the hyphae and root surface can absorb Hg so that Hg translocation into roots can be inhibited, and inside the roots, it changes cell wall components of plant, hence possibly enhancing the sequestration of Hg (Yu et al, 2010).…”