Effects of copper, lead, and cadmium on the sorption of 2,4,6-trichlorophenol onto and desorption from wheat ash and two commercial humic acids.

The effects of copper (Cu2+), lead (Pb2+), and cadmium (Cd2+) on the sorption of 2,4,6-trichlorophenol (TCP) to and desorption from wheat ash and two commercial humic acids were studied. Copper and Pb2+ diminished the sorption of TCP onto all adsorbents, and made desorption of TCP less hysteretic from ash and German humic acids (GeHA), but more hysteretic from Tianjin humic acids (TJHA). Cadmium had little effect on TCP sorption and desorption.

A comparison of the rhizosphere-based method with DTPA, EDTA, CaCl2, and NaNO3 extraction methods for prediction of bioavailability of metals in soil to barley.

A rhizosphere-based method was compared with DTPA, EDTA, CaCl2, and NaNO3 extraction methods for the evaluation of bioavailability of heavy metals in soil to barley. The extractable amounts of Cr, Cu, Zn and Cd analyzed by the rhizosphere-based method correlated significantly with the metal content of barley roots. The extractable metals identified by DTPA, EDTA, CaCl2 and NaNO3 methods exhibited relatively poor or no correlation with the metal content of barley roots.

Comparison of a rhizosphere-based method with other one-step extraction methods for assessing the bioavailability of soil metals to wheat.

There is no method recognized as a universal approach for evaluation of bioavailability of heavy metals in soil. Based on the simulation of the rhizosphere soil conditions and integration of the combined effects of root-soil interactions as a whole, a rhizosphere-based method has been proposed. Wet fresh rhizosphere soil was extracted by low-molecular-weight organic acids (LMWOAs) to fractionate metal fractions of soil pools, which were then correlated with the metal contents of wheat roots and shoots.