Micronutrients and toxic trace metals in the bulk and rhizospheric soil of the spontaneous vegetation at an abandoned copper mine in Galicia (NW Spain)

Distance-dependent varieties of microbial community structure and metabolic functions in the rhizosphere of Sedum alfredii Hance during phytoextraction of a cadmium-contaminated soil

“…For instance, Kwonrae et al (2010) reported an increased pH in the rhizosphere of Indian mustard in the phytoremediation process. Labile organic C produced by degradation of roots or exudation of organic compounds may influence the solubility of metals due to formation of metal-C complexes (Otero et al 2012). Similar to our study, the increasing of labile C in the rhizosphere of hyperaccumulators was reported by previous studies (Kim et al 2010;Wei and Twardowska 2013).…”

Copper accumulation and changes in soil physical–chemical properties promoted by native plants in ​​an abandoned mine site in northeastern Brazil: Implications for restoration of mine sites

“…The pseudototal concentration, which is extracted by strong acids, may comprise forms of metals that are scarcely accessible to plants, such as crystalline forms of primary minerals or very stable organometallic complexes (Fernandez-Calvino et al, 2009). The Mehlich3 extractant is widely used to extract the potentially bioavailable metal, as it extracts the readily bioavailable fraction plus the fractions that may be rendered readily available by small changes in soil conditions, such as those provided by the plant rhizosphere (Mehlich, 1984;Monterroso et al, 1999;Otero et al, 2012). The metal extracted by a salt solution such as MgCl 2 represents the fraction that is weakly adsorbed on soil surfaces and is therefore readily available to plants (Filgueiras et al, 2002).…”

Soil processes and nutrient bioavailability in the rhizosphere of Bolax gummifera in a subantarctic environment (Martial Mountains, Ushuaia—Argentina)

“…Previous research has shown that the microbial population in the RS differs either quantitatively or qualitatively from bulk soil and may vary with plant species, root zone and soil type (Rengel and Macchner, 2005;Marschner et al, 2001). The pH of the RS is also lower (Marschner and Römheld, 1996;Nye, 1986;Otero et al, 2012), whereas the cation exchange capacity (CEC) and metal availability are higher in RS than in bulk soil (Jong-Bae Chung and Zasoski, 1994;Sarkar and Wynjones, 1982). Our results also provide clear evidence that the rhizosphere of B. gummifera is a very different microenvironment from the bulk soils, despite the study area being in a cold climate zone where pedological processes are still incipient.…”

“…1), which provides most plant cover in the area and has important ecological implications (Cavieres and Arroyo, 2002), and three bulk soil samples (0-5 cm with no plant cover) were collected. The RS has been considered as the soil fraction that remains attached to the roots after slight shaking (Corti et al, 2005;Otero et al, 2012). Two types of RS samples were collected: samples comprising the upper 5 cm (Rh5) of soil, where the roots are densest, and samples from between the upper 5 cm and the bedrock, usually between 5 and 15 cm (Rh15).…”

“…Soil organic matter (SOM) participates in many pedogenetic processes such as the formation of soil structure (aggregation), metal complexation, water retention, nutrient supply and acidification. The negative and highly significant correlation between TOC and pH (pH H2O : r s = − 0.939, p b 0.001; pH KCl : r s = − 0.782, n = 10, p = 0.008, n = 11) can be considered as a direct effect exerted by roots on the soil (Marschner and Römheld, 1996;Nye, 1986;Otero et al, 2012). Acidification of the rhizosphere occurs as a consequence of several factors such as respiration of microorganisms and roots, release of organic acids (e.g.…”