The use of differential pulse anodic stripping voltammetry and diffusive gradient in thin films for heavy metals speciation in soil solution

摘要

In the soil solutions obtained in situ with suction cups from soils (Cambisol and Fluvisol) of pot experiment with Salix smithiana Smith, Lolium perenne L. and Thlaspi caerulescens J. & C. Presl heavy metals species (Cd, Pb and Cu) were assayed by differential pulse anodic stripping voltammetry and diffusive gradient in thin films. Prediction of accumulation performed best at free metal ion concentrations in unchanged pH (in 10-3 mol L~(-1) NaClO4 base electrolyte). The speciation provided by differential pulse anodic stripping voltammetry according to pH can provide a detailed description of the soil solution matrix. The concentration of free metals in unchanged pH represents a small part of the total content and varied from 0.04 to 0.75% with two exceptions found for accumulating plants (the content of Cd2+ in the soil solution from T. caerulescens was about 6% and the content of Cu2+ in the soil solution from S. smithiana was about 30%). The available concentration as determined by diffusive gradient in thin films was not in correlation with the heavy metals concentration in plant biomass.