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Geochemical Environments
Published in Arthur W. Hounslow, Water Quality Data, 2018
In a study of heavy metal relationships beneath a municipal landfill in central Pennsylvania, Suarez and Langmuir (1976) found that the major source of heavy metals in these soils was hydrous manganese oxide. The manganese oxide exceeded iron oxide adsorption by at least a factor of 10 for some heavy metals, possibly because of the greater crystallinity of the iron oxides as well as the lower pH. They also noted that the metal oxides and trace metals existed predominantly in coatings on quartz grains and were not significantly concentrated in the < 15-μm fraction. These conclusions differ little from well-established geochemical data such as reported by Rankama and Sahama (1950), namely, that oxidate sediments rich in Mn commonly contain notable amounts of Li, K, Ca, Ba, B, Ti, Co, Ni, Cu, Zn, Tl, Pb, and W.
Study on the migration and transformation of arsenic and antimony in the rhizosphere of plants grown in zinc smelting slag
Published in Chemistry and Ecology, 2021
Hang Sun, Xinlong Li, Yonggui Wu
Iron and aluminum oxides in soil are formed by the complete weathering of silicate minerals under specific hydrothermal conditions on the surface and have a significant impact on the physical and chemical properties of the soil [36]. Arsenic and antimony usually exist in soil in the form of neutral molecules or oxygen-containing anions [3]. The point of zero charge (PZC) of iron and aluminum oxides are at about 7 and are often positively charged on the surface of environmental media [37,38]. Therefore, the surface adsorption of iron and aluminum oxides is an important mechanism for the fixation of arsenic and antimony in slags. The PZC of iron oxide is approximately 7; when the pH of the adsorption system is close to or more than the iron oxide PZC, the negative surface charge of iron oxide will increase; the same charges of arsenic, antimony, and oxygen anion are mutually exclusive, leading to a decrease in the adsorption [39]. As a result, a lower pH of slag will increase the iron oxide adsorption of arsenic and antimony. The PZC of most aluminium oxides are approximately pH=6, and present a net negative charge in neutral and alkaline environments; therefore, the adsorption capacity of aluminum oxides for arsenic and antimony in slags is weak [40]. The PCA analysis also showed that free iron and aluminum oxide were positively correlated with arsenic and antimony.