Using chemical fractionation to evaluate the phytoextraction of cadmium by switchgrass from Cd-contaminated soils

Abstract

The purpose of this study is to evaluate the phytoextraction of cadmium (Cd) from contaminated soils by switchgrass (Panicum virgatum L.), which is a promising energy crop with high biomass. Two ecotypes of switchgrass cultivars, Alamo and Blackwell, were investigated in a pot experiment. Dry weight and plant Cd concentration of the switchgrass plants growing on Cd-spiked soils (0, 20, and 60 mg Cd kg(-1) soil) with chelating agent amendments (1 g kg(-1) citric acid [CA] and 0.1 g kg(-1) ethylene diaminetetraacetic acid [EDTA]) were measured to examine the phytotoxicity and accumulation of Cd in the switchgrass. Fractions of Cd (F1, exchangeable; F2, carbonate; F3, Fe-Mn oxide; F4, organic matter; F5, residual) for the soils sampled at the time of harvesting were also determined using chemically sequential extractions. In the results, the dry weight of the switchgrass decreased with increasing Cd, with a significant dry weight reduction when Cd exceeded 20 mg kg(-1). However, the high Cd spike of 60 mg kg(-1) was not lethal to Alamo and Blackwell, which suggests that switchgrass plants can tolerate Cd and grow in contaminated soils. Compared with the control, the CA and EDTA amendments had no adverse effect on the growth of switchgrass plants. With regard to Cd accumulation, higher plant Cd concentrations were frequently found after CA amendment in Alamo; however, the Cd concentrations of Blackwell plants may increase when amended with EDTA. On the basis of the fractionation of soil Cd, dry weight and plant Cd concentration could be expressed as a function of Cd fractionation to predict the phytoextraction of Cd. Thus, the fractionation of Cd is a useful approach for evaluating the phytoextraction of Cd by switchgrass in contaminated soils. According to the comparison of phytoextractions of Cd between Alamo and Blackwell, Alamo plants removed substantially more Cd from Cd-spiked soils than Blackwell. Therefore, Alamo is better suited for the phytoextraction of Cd from contaminated soils.

Extraction of Heavy Metals from Contaminated Soil by Two Amaranthus spp.

“…And there were no visible symptoms of chlorosis and necrosis. The result is similar with Chen et al [29].…”

Roles of rhizosphere and root-derived organic acids in Cd accumulation by two hot pepper cultivars

“…It was worth noting that the proportions of exchangeable Cd obviously increased in the T2 and T3 treatments compared with those in the T1 treatment (Table 3), possibly due to the low soil pH and the addition of cadmium nitrate. Similarly, Chen et al (2011) also reported that the exchangeable Cd fraction greatly increased with increasing Cd supply in the acid Pinchen soil. As for the difference of other Cd fractions such as Fe/Mn oxide and organic matter forms between YCT and JFZ, a possible explanation could be given by considering the difference of root exudates between them.…”

Morph‐physiological responses of two switchgrass (Panicum virgatum L.) cultivars to cadmium stress

“…For example, Entry and Watrud (1998) found that 'Alamo' can accumulate 137 Cs and 90 Sr from a contaminated growth medium. In addition, two switchgrass cultivars ('Alamo' and 'Blackwell') were used to evaluate the phytoextraction of Cd by switchgrass from Cd-contaminated soils by Chen et al (2011). Reed et al (1999Reed et al ( , 2002 reported that switchgrass could accumulate Cd under low pH conditions.…”

“…and sunflower (Helianthus annuus L.) (Shahandeh and Hossner 2000). In addition, two switchgrass cultivars ('Alamo' and 'Blackwell') were used to evaluate the phytoextraction of Cd by switchgrass from Cd-contaminated soils by Chen et al (2011). The results showed that 'Alamo' is better suited for the phytoextraction of Cd from contaminated soils.…”