Aqueous extracts from the selected hyperaccumulators used as soil additives significantly improve accumulation capacity of Solanum nigrum L. for Cd and Pb.

The effects of soil treatment with aqueous extracts from three hyperaccumulators on Cd and Pb accumulation by Solanum nigrum L. were determined. The stem (S-RG) and leaf extracts (L-RG) of Rorippaglobosa (Turcz.) Thell., and stem extract (S-BP) of Bidens pilosa L. significantly enhanced Cd and Pb total accumulation capacity of S. nigrum compared to control (by 44 %, 47 %, and 29 % for Cd and by 28 %, 28 % and 21 % for Pb, respectively), while EDTA caused its 9 % and 15 % decrease due to the plant biomass reduction (by 33 %). The leaching experiments reflected affinity of additives to metal mobilization in soils. The concentrations of total organic acid in S-RG, L-RG and S-BP were the highest among studied extracts, which besides the beneficial effect on the soil environment (microbe number and enzyme activities), may be partial reasons of strong promotion of S. nigrum accumulation capacity for Cd and Pb. It was shown that hyperaccumulation properties of a plant are not a prerequisite of enhancing effect of the plant-based soil additive on the metal accumulation capacity of the target living hyperaccumultor. The plant-based chelators were found to be promising candidates for EDTA and other chemicals replacement in promoting efficient and environmentally safe phytoremediation.

Effect of different nitrogenous nutrients on the cadmium hyperaccumulation efficiency of Rorippa globosa (Turcz.) Thell.

This experiment was used to explore whether the 11 nitrogenous nutrients affect the hyperaccumulation of Rorippa globosa (Turcz.) Thell. to Cd. Pot culture experiments using soil spiked with Cd as CdCl2·2.5H2O and 11 nitrogen-containing chemicals were conducted to determine the efficiency of the accumulation of Cd by R. globosa. Application of all 11 nitrogenous nutrients significantly (p < 0.05) enhanced Cd accumulation by R. globosa (Turcz.) Thell. Two major modes of Cd accumulation were observed: (i) through increase of biomass yield without reduction of Cd uptake and (ii) through increase of Cd uptake efficiency in parallel with increase of biomass yield. Bicarbonate > phosphate > chloride compounds of NH4 enhanced the biomass yield to the greatest extent, while oxalate > nitrate > chloride > and bicarbonate caused a significant increase of Cd uptake by R. globosa. Competition between N and Cd translocation caused either significant reduction of Cd translocation factor or decrease of biomass yield. Of studied nutrients, ammonium bicarbonate NH4HCO3 and ammonium chloride NH4Cl exerted the best joint effect of these two processes on the efficiency of R. globosa as a Cd hyperaccumulator. Application of these chemicals caused increase of Cd concentrations in roots of R. globosa by 35.1 and 41.1 %, and in shoots by 13.9 and 56.4 %, while biomasses of roots increased by 5.8- and 3.8-fold and in shoots by 7.4-fold, and 6.4-fold, respectively, compared to the control. As a result, accumulated load (µg pot(-1)) of Cd in roots increased by 8.2- and 5.8-fold and in shoots by 8.6- and 10.6-fold in both pots. Consequently, chemicals (NH4HCO3 and NH4Cl) that enhanced both Cd enrichment and biomass yield had the greatest effect on the bioaccumulation capacity of R. globosa.

Profiling of glucosinolates and flavonoids in Rorippa indica (Linn.) Hiern. (Cruciferae) by UHPLC-PDA-ESI/HRMS(n).

An UHPLC-PDA-ESI/HRMS(n) profiling method was used to identify the glucosinolates and flavonoids of Rorippa indica (Cruciferae), a wild vegetable and Chinese herb used to treat cough, diarrhea, and rheumatoid arthritis. Thirty-three glucosinolates, more than 40 flavonol glycosides, and 18 other phenolic and common organic compounds were identified. The glucosinolates and polyphenols were separated by UHPLC. High-resolution deprotonated molecules provided high accuracy mass values that were used to determine formulas and provide putative identification of the glucosinolates and flavonoids. The fragments from multistage mass spectrometry were used to elucidate the structures. The concentrations of the main components were based on UV peak areas and molar relative response factors with a single calibration standard. This study found this plant to be a rich source for glucosinolates, containing 24 new glucosinolates, including 14 glucosylated glucosinolates that were previously unidentified.