Abstract
Differential pulse polarography (DPP) was used to assess the interaction of Pb2+ with various humic acid analogs and several humic acids. DPP analysis demonstrated that the reduction peak maximum (Ep) for Pb2+ shifted to more negative values in the presence of humic acids and humic acid analogs. The observed Ep for Pb2+ in the presence of humic acids and humic acid analogs is influenced by ligand concentration, solution pH and Pb2+ concentration. Shifts in the Ep for Pb2+ are related to the reduction potential and can be rationalized using the Lingane equation.
Highlights
When metal cations interact with natural organic matter, metal ligand complexes of various strengths can form
In a previous publication, using anodic stripping voltammetry (ASV), we demonstrated that copper is strongly bound by water-extractable soil organic matter and by humic acids [13]
Our observations indicated that the presence of various ligating small molecules (3,4-dihyroxybenzoic acid and salicylic acid) and humic acids results in a shift in the Ep for Pb2+ to a more negative voltage
Summary
When metal cations interact with natural organic matter, metal ligand complexes of various strengths can form. Natural organic matter in soil and water can have a significant influence on chemical speciation of various metals in the environment. Grosell et al [1]. Demonstrated that humic acid can reduce the toxicity of lead for fathead minnows during laboratory tank exposure. García-Mina et al [2] reviewed the role that metal-humic complexes can play in plant micronutrient uptake. Senesi and Loffredo [3] reviewed the role of humic substances on the speciation of metals in soils. Senesi and Lofferedo [4] reviewed the various spectroscopic methods utilized for studying the influence of humic acid metal complexes on metal speciation in soil
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