Metals complexation with humic acids in surface water of different natural–climatic zones

M I Dinu

doi:10.1051/e3sconf/20130132011

Abstract

Humic acids extracted from different soils. The stability constants of metal humates and acid dissociation constant humic acids were calculated. Forms of metals in natural waters was determined with use account their chemical composition and content and properties of organic matter. We assessed metals speciation in water objects with account for competitive reactions resulting in formation of hydroxide, hydrocarbonate, sulfate, and chloride metal complexes and obtained a competitive series of metal activity in natural waters of the zones considered.

Highlights

Ions of metals (IM) in aquatic systems are involved in existing migration cycles
Chrome, and manganese are formed in a 1:1 ratio with humic acids (HA) of all selected natural zones and with low stability constants of complexes, which is related to the physicochemical properties of metal ions
The stability constants of complexes are different for most metal ions with humic matter (HM) of natural zones (Table 1), which indicates the specificity of the complexing processes

Summary

Introduction

Ions of metals (IM) in aquatic systems are involved in existing migration cycles They migrate, were accumulating in all components of the aquatic environment: in the water itself, suspended matter, bottom sediments (BS), and living organisms [2,3,4,5, 23–27]. The natural–climatic zones feature various ratios of fulvic (FA) and humic acids. The concentrations of these acids in surface waters attain 1–100 mg/l [2, 3]. An important specific feature of metals as contamination elements is the fact that when they occur in the environment, their potential toxicity and bioavailability depend significantly on their speciation. The most important organic ligands are humic matter (HM) washed out from soils; inorganic complexes formed include hydroxide groups, hydrocarbonates, sulfates, and chlorides. Our current task is to develop methods that would make it possible to forecast element speciation predefining toxic properties of water by the chemical composition of the water

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Conclusion