Forms of Gold and Arsenic in Surface Sediments at the Novye Peski Gold Deposit and Their Sorption by Humic Acid

Abstract

Forms of gold and arsenic, as one of the main pathfinders, were researched in the podzolic, illuvial, and parent material horizons of podzol soil at the Novye Peski gold deposit. Forms of gold and arsenic were studied with the sequential extraction method. The results of this study showed that the main forms of gold are water-soluble, bound to organic matter, and “insoluble”; for arsenic: bound to Fe and Mn-(oxy)hydroxides and bound to organic matter. The form bound to organic matter was considered in detail and gold and arsenic were analyzed in humic and fulvic acids solutions extracted from podzol soil. It was determined that gold is mainly bound to humic acid (HA), and arsenic to fulvic acid. Due to the prevalence of the form of gold bound to humic acid, the modelling process of different gold and arsenic (III) contents sorption on solid humic acid were observed and data on quantity of adsorbed ions per unit mass of HA and recovery ratio were obtained. More than 90% gold recovery rate was observed for concentrations less than 10 µg/cm3 and for arsenic it was in a range of 8–15%.