Assessment of Heavy Metal Bioavailability in Contaminated Soils from a Former Mining Area (La Union, Spain) Using a Rhizospheric Test

Abstract

A rhizospheric biotest, consisting of a thin layer of substratum in close contact with roots of Lolium multiflorum, was used on two contrasting contaminated soils (Cabezo and Brunita) issued from a former mining area in La Union (Spain). On top of this biotest, soil characterisation, including CaCl 2 selective extractions, was performed. Total heavy metal concentrations were the highest in the soil from Cabezo, but CaCl 2 extractions indicated higher heavy metal mobilities in Brunita soil. On the base of heavy metal concentrations and biomass production in L. multiflorum seedlings, availability assessed by the rhizospheric biotest was higher than the values obtained from CaCl 2 extraction, except for Mn and Pb. Rhizospheric biotest also revealed higher heavy metal bioavailability for Cabezo. The low pH of Brunita (3.47) could explain the high CaCl 2 -extractable heavy metal concentrations as well as the high transfer factor found for Cu, Mn and Zn in this substrate. Cu, Mn and Zn toxicities were also detected for shoot tissues. Transpiration rates were clearly lower for seedlings exposed to Brunita than for those exposed to Cabezo, while water use efficiency was higher for the former (4.8 mgDWml −1 ) than for the latter (3.8 mgDWml −1 ). Iron nutrition was found to interfere with heavy metal root absorption, mainly through negative interactions during root absorption. It is concluded that rhizospheric test offers the advantage to consider the root-soil interactions in a dynamic perspective and constitutes a useful tool for the assessment of heavy metal availability on contaminated soils. Heavy metal bioavailability assessment should not be based on only one measure alone, but on different and complementary approaches.

Ecological restoration of an acidic Cd contaminated soil using bamboo biochar application

“…Both CaCl 2 and DTPA extractions can be used as indicators for Cd solubility, bioavailability and mobility in soils (Kalis et al, 2007;Cui et al, 2011;Lambrechts et al, 2011;Bian et al, 2014). Amounts of Cd in DTPA extraction were higher than those in CaCl 2 extraction in all biochar and Cd treatments.…”

Transpiration flow controls Zn transport in Brassica napus and Lolium multiflorum under toxic levels as evidenced from isotopic fractionation

“…For the culture experiment, two plant species were chosen on the basis of their high and fast biomass productivity, their suitability to the experiment conditions (previously tested by Chaignon and Hinsinger, 2003;Lambrechts et al, 2011), and their distinct physiological mechanisms: Brassica napus L. cv Adelie (rape) and Lolium multiflorum L. cv Meribel (ryegrass). L. multiflorum is a metal-tolerant monocotyledonous plant species, while B. napus belongs to the dicotyledonous species and is well known to be tolerant for some abiotic stresses, like high metal contents in soils (Houben et al, 2013;Marchiol et al, 2004).…”

Arsenic and Heavy Metal Uptake and Accumulation in Native Plant Species from Soils Polluted by Mining Activities

“…Weak neutral salt solutions have been reported to be useful to evaluate the impact of trace elements on plants and soil biological activity (Kabata-Pendias 2004), and CaCl 2 and phosphate buffer has been successfully used for this purpose (Antosiewicz et al 2008;Lambrechts et al 2011;Houba et al 2000;Pueyo et al 2005).…”